]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/kern/kern_credential.c
xnu-1228.5.18.tar.gz
[apple/xnu.git] / bsd / kern / kern_credential.c
index 59c1a24eefba6228d7b51b0134ce43c3663d5944..89d2e8dbf2ddfc777cd164b00cf685d5e6ed61bf 100644 (file)
@@ -1,27 +1,40 @@
 /*
- * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2004-2007 Apple Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
- * The contents of this file constitute Original Code as defined in and
- * are subject to the Apple Public Source License Version 1.1 (the
- * "License").  You may not use this file except in compliance with the
- * License.  Please obtain a copy of the License at
- * http://www.apple.com/publicsource and read it before using this file.
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
  * 
- * This Original Code and all software distributed under the License are
- * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
- * License for the specific language governing rights and limitations
- * under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
  * 
- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ */
+/*
+ * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
+ * support for mandatory and extensible security protections.  This notice
+ * is included in support of clause 2.2 (b) of the Apple Public License,
+ * Version 2.0.
  */
 
 /*
- * Kernel Authorization framework: Management of process/thread credentials and identity information.
+ * Kernel Authorization framework: Management of process/thread credentials
+ * and identity information.
  */
 
 
 #define MACH_ASSERT 1  /* XXX so bogus */
 #include <kern/assert.h>
 
-#define CRED_DIAGNOSTIC 1
+#if CONFIG_MACF
+#include <security/mac.h>
+#include <security/mac_framework.h>
+#endif
+
+#define CRED_DIAGNOSTIC 0
+
+# define NULLCRED_CHECK(_c)    do {if (!IS_VALID_CRED(_c)) panic("%s: bad credential %p", __FUNCTION__,_c);} while(0)
+
+/*
+ * Credential debugging; we can track entry into a function that might
+ * change a credential, and we can track actual credential changes that
+ * result.
+ *
+ * Note:       Does *NOT* currently include per-thread credential changes
+ */
+
+#if DEBUG_CRED
+#define        DEBUG_CRED_ENTER                printf
+#define        DEBUG_CRED_CHANGE               printf
+extern void kauth_cred_print(kauth_cred_t cred);
+
+#include <libkern/OSDebug.h>   /* needed for get_backtrace( ) */
+
+int is_target_cred( kauth_cred_t the_cred );
+void get_backtrace( void );
+
+static int sysctl_dump_creds( __unused struct sysctl_oid *oidp, __unused void *arg1, 
+                                                         __unused int arg2, struct sysctl_req *req );
+static int
+sysctl_dump_cred_backtraces( __unused struct sysctl_oid *oidp, __unused void *arg1, 
+                                                        __unused int arg2, struct sysctl_req *req );
+
+#define MAX_STACK_DEPTH 8
+struct cred_backtrace {
+       int                             depth;
+       void *                  stack[ MAX_STACK_DEPTH ];
+};
+typedef struct cred_backtrace cred_backtrace;
+
+#define MAX_CRED_BUFFER_SLOTS 200
+struct cred_debug_buffer {
+       int                             next_slot;
+       cred_backtrace  stack_buffer[ MAX_CRED_BUFFER_SLOTS ];  
+};
+typedef struct cred_debug_buffer cred_debug_buffer;
+cred_debug_buffer * cred_debug_buf_p = NULL;
+
+#else  /* !DEBUG_CRED */
 
-# define NULLCRED_CHECK(_c)    do {if (!IS_VALID_CRED(_c)) panic("bad credential %p", _c);} while(0)
+#define        DEBUG_CRED_ENTER(fmt, ...)      do {} while (0)
+#define        DEBUG_CRED_CHANGE(fmt, ...)     do {} while (0)
+
+#endif /* !DEBUG_CRED */
 
 /*
  * Interface to external identity resolver.
  *
- * The architecture of the interface is simple; the external resolver calls in to
- * get work, then calls back with completed work.  It also calls us to let us know
- * that it's (re)started, so that we can resubmit work if it times out.
+ * The architecture of the interface is simple; the external resolver calls
+ * in to get work, then calls back with completed work.  It also calls us
+ * to let us know that it's (re)started, so that we can resubmit work if it
+ * times out.
  */
 
 static lck_mtx_t *kauth_resolver_mtx;
@@ -93,9 +158,9 @@ TAILQ_HEAD(kauth_resolver_done_head, kauth_resolver_work)    kauth_resolver_done;
 static int     kauth_resolver_submit(struct kauth_identity_extlookup *lkp);
 static int     kauth_resolver_complete(user_addr_t message);
 static int     kauth_resolver_getwork(user_addr_t message);
+static int     kauth_resolver_getwork2(user_addr_t message);
 
-#define KAUTH_CRED_PRIMES_COUNT 7
-static const int kauth_cred_primes[KAUTH_CRED_PRIMES_COUNT] = {97, 241, 397, 743, 1499, 3989, 7499};
+static const int kauth_cred_primes[KAUTH_CRED_PRIMES_COUNT] = KAUTH_CRED_PRIMES;
 static int     kauth_cred_primes_index = 0;
 static int     kauth_cred_table_size = 0;
 
@@ -117,6 +182,34 @@ static void kauth_cred_hash_print(void);
 static void kauth_cred_print(kauth_cred_t cred);
 #endif
 
+
+/*
+ * kauth_resolver_init
+ *
+ * Description:        Initialize the daemon side of the credential identity resolver
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (void)
+ *
+ * Notes:      Intialize the credential identity resolver for use; the
+ *             credential identity resolver is the KPI used by the user
+ *             space credential identity resolver daemon to communicate
+ *             with the kernel via the identitysvc() system call..
+ *
+ *             This is how membership in more than 16 groups (1 effective
+ *             and 15 supplementary) is supported, and also how UID's,
+ *             UUID's, and so on, are translated to/from POSIX credential
+ *             values.
+ *
+ *             The credential identity resolver operates by attempting to
+ *             determine identity first from the credential, then from
+ *             the kernel credential identity cache, and finally by
+ *             enqueueing a request to a user space daemon.
+ *
+ *             This function is called from kauth_init() in the file
+ *             kern_authorization.c.
+ */
 void
 kauth_resolver_init(void)
 {
@@ -127,10 +220,27 @@ kauth_resolver_init(void)
        kauth_resolver_mtx = lck_mtx_alloc_init(kauth_lck_grp, 0/*LCK_ATTR_NULL*/);
 }
 
+
 /*
- * Allocate a work queue entry, submit the work and wait for completion.
+ * kauth_resolver_submit
  *
- * XXX do we want an 'interruptible' flag vs. always being interruptible?
+ * Description:        Submit an external credential identity resolution request to
+ *             the user space daemon.
+ *
+ * Parameters: lkp                             A pointer to an external
+ *                                             lookup request
+ *
+ * Returns:    0                               Success
+ *             EWOULDBLOCK                     No resolver registered
+ *             EINTR                           Operation interrupted (e.g. by
+ *                                             a signal)
+ *             ENOMEM                          Could not allocate work item
+ *             ???                             An error from the user space
+ *                                             daemon
+ *
+ * Notes:      Allocate a work queue entry, submit the work and wait for
+ *             the operation to either complete or time out.  Outstanding
+ *             operations may also be cancelled.
  */
 static int
 kauth_resolver_submit(struct kauth_identity_extlookup *lkp)
@@ -169,14 +279,17 @@ kauth_resolver_submit(struct kauth_identity_extlookup *lkp)
        workp->kr_result = 0;
 
        /*
-        * We insert the request onto the unsubmitted queue, the call in from the
-        * resolver will it to the submitted thread when appropriate.
+        * We insert the request onto the unsubmitted queue, the call in from
+        * the resolver will it to the submitted thread when appropriate.
         */
        KAUTH_RESOLVER_LOCK();
        workp->kr_seqno = workp->kr_work.el_seqno = kauth_resolver_sequence++;
        workp->kr_work.el_result = KAUTH_EXTLOOKUP_INPROG;
 
-       /* XXX as an optimisation, we could check the queue for identical items and coalesce */
+       /*
+        * XXX As an optimisation, we could check the queue for identical
+        * XXX items and coalesce them
+        */
        TAILQ_INSERT_TAIL(&kauth_resolver_unsubmitted, workp, kr_link);
 
        wakeup_one((caddr_t)&kauth_resolver_unsubmitted);
@@ -202,9 +315,10 @@ kauth_resolver_submit(struct kauth_identity_extlookup *lkp)
                *lkp = workp->kr_work;
        
        /*
-        * If the request timed out and was never collected, the resolver is dead and
-        * probably not coming back anytime soon.  In this case we revert to no-resolver
-        * behaviour, and punt all the other sleeping requests to clear the backlog.
+        * If the request timed out and was never collected, the resolver
+        * is dead and probably not coming back anytime soon.  In this
+        * case we revert to no-resolver behaviour, and punt all the other
+        * sleeping requests to clear the backlog.
         */
        if ((error == EWOULDBLOCK) && (workp->kr_flags & KAUTH_REQUEST_UNSUBMITTED)) {
                KAUTH_DEBUG("RESOLVER - request timed out without being collected for processing, resolver dead");
@@ -216,7 +330,10 @@ kauth_resolver_submit(struct kauth_identity_extlookup *lkp)
                    wakeup(killp);
        }
        
-       /* drop our reference on the work item, and note whether we should free it or not */
+       /*
+        * drop our reference on the work item, and note whether we should
+        * free it or not
+        */
        if (--workp->kr_refs <= 0) {
                /* work out which list we have to remove it from */
                if (workp->kr_flags & KAUTH_REQUEST_DONE) {
@@ -247,8 +364,29 @@ kauth_resolver_submit(struct kauth_identity_extlookup *lkp)
        return(error);
 }
 
+
 /*
- * System call interface for the external identity resolver.
+ * identitysvc
+ *
+ * Description:        System call interface for the external identity resolver.
+ *
+ * Parameters: uap->message                    Message from daemon to kernel
+ *
+ * Returns:    0                               Successfully became resolver
+ *             EPERM                           Not the resolver process
+ *     kauth_authorize_generic:EPERM           Not root user
+ *     kauth_resolver_complete:EIO
+ *     kauth_resolver_complete:EFAULT
+ *     kauth_resolver_getwork:EINTR
+ *     kauth_resolver_getwork:EFAULT
+ *
+ * Notes:      This system call blocks until there is work enqueued, at
+ *             which time the kernel wakes it up, and a message from the
+ *             kernel is copied out to the identity resolution daemon, which
+ *             proceed to attempt to resolve it.  When the resolution has
+ *             completed (successfully or not), the daemon called back into
+ *             this system call to give the result to the kernel, and wait
+ *             for the next request.
  */
 int
 identitysvc(__unused struct proc *p, struct identitysvc_args *uap, __unused register_t *retval)
@@ -315,40 +453,152 @@ identitysvc(__unused struct proc *p, struct identitysvc_args *uap, __unused regi
        return(0);
 }
 
+
 /*
- * Get work for a caller.
+ * kauth_resolver_getwork_continue
+ *             
+ * Description:        Continuation for kauth_resolver_getwork
+ *
+ * Parameters: result                          Error code or 0 for the sleep
+ *                                             that got us to this function
+ *
+ * Returns:    0                               Success
+ *             EINTR                           Interrupted (e.g. by signal)
+ *     kauth_resolver_getwork2:EFAULT
+ *
+ * Notes:      See kauth_resolver_getwork(0 and kauth_resolver_getwork2() for
+ *             more information.
  */
 static int
-kauth_resolver_getwork(user_addr_t message)
+kauth_resolver_getwork_continue(int result)
+{
+       thread_t thread;
+       struct uthread *ut;
+       user_addr_t message;
+
+       if (result) {
+               KAUTH_RESOLVER_UNLOCK();
+               return(result);
+       }
+
+       /*
+        * If we lost a race with another thread/memberd restarting, then we
+        * need to go back to sleep to look for more work.  If it was memberd
+        * restarting, then the msleep0() will error out here, as our thread
+        * will already be "dead".
+        */
+       if (TAILQ_FIRST(&kauth_resolver_unsubmitted) == NULL) {
+               int error;
+
+               error = msleep0(&kauth_resolver_unsubmitted, kauth_resolver_mtx, PCATCH, "GRGetWork", 0, kauth_resolver_getwork_continue);
+               KAUTH_RESOLVER_UNLOCK();
+               return(error);
+       }
+
+       thread = current_thread();
+       ut = get_bsdthread_info(thread);
+       message = ut->uu_kauth.message;
+       return(kauth_resolver_getwork2(message));
+}
+
+
+/*
+ * kauth_resolver_getwork2
+ *
+ * Decription: Common utility function to copy out a identity resolver work
+ *             item from the kernel to user space as part of the user space
+ *             identity resolver requesting work.
+ *
+ * Parameters: message                         message to user space
+ *
+ * Returns:    0                               Success
+ *             EFAULT                          Bad user space message address
+ *
+ * Notes:      This common function exists to permit the use of continuations
+ *             in the identity resoultion process.  This frees up the stack
+ *             while we are waiting for the user space resolver to complete
+ *             a request.  This is specifically used so that our per thread
+ *             cost can be small, and we will therefore be willing to run a
+ *             larger number of threads in the user space identity resolver.
+ */
+static int
+kauth_resolver_getwork2(user_addr_t message)
 {
        struct kauth_resolver_work *workp;
        int             error;
 
-       KAUTH_RESOLVER_LOCK();
-       error = 0;
-       while ((workp = TAILQ_FIRST(&kauth_resolver_unsubmitted)) == NULL) {
-               error = msleep(&kauth_resolver_unsubmitted, kauth_resolver_mtx, PCATCH, "GRGetWork", 0);
-               if (error != 0)
-                       break;
-       }
-       if (workp != NULL) {
-               if ((error = copyout(&workp->kr_work, message, sizeof(workp->kr_work))) != 0) {
-                       KAUTH_DEBUG("RESOLVER - error submitting work to resolve");
-                       goto out;
-               }
-               TAILQ_REMOVE(&kauth_resolver_unsubmitted, workp, kr_link);
-               workp->kr_flags &= ~KAUTH_REQUEST_UNSUBMITTED;
-               workp->kr_flags |= KAUTH_REQUEST_SUBMITTED;
-               TAILQ_INSERT_TAIL(&kauth_resolver_submitted, workp, kr_link);
+       /*
+        * Note: We depend on the caller protecting us from a NULL work item
+        * queue, since we must have the kauth resolver lock on entry to this
+        * function.
+        */
+       workp = TAILQ_FIRST(&kauth_resolver_unsubmitted);
+
+       if ((error = copyout(&workp->kr_work, message, sizeof(workp->kr_work))) != 0) {
+               KAUTH_DEBUG("RESOLVER - error submitting work to resolve");
+               goto out;
        }
+       TAILQ_REMOVE(&kauth_resolver_unsubmitted, workp, kr_link);
+       workp->kr_flags &= ~KAUTH_REQUEST_UNSUBMITTED;
+       workp->kr_flags |= KAUTH_REQUEST_SUBMITTED;
+       TAILQ_INSERT_TAIL(&kauth_resolver_submitted, workp, kr_link);
 
 out:
        KAUTH_RESOLVER_UNLOCK();
        return(error);
 }
 
+
+/*
+ * kauth_resolver_getwork
+ *
+ * Description:        Get a work item from the enqueued requests from the kernel and
+ *             give it to the user space daemon.
+ *
+ * Parameters: message                         message to user space
+ *
+ * Returns:    0                               Success
+ *             EINTR                           Interrupted (e.g. by signal)
+ *     kauth_resolver_getwork2:EFAULT
+ *
+ * Notes:      This function blocks in a continuation if there are no work
+ *             items available for processing at the time the user space
+ *             identity resolution daemon makes a request for work.  This
+ *             permits a large number of threads to be used by the daemon,
+ *             without using a lot of wired kernel memory when there are no
+ *             acctual request outstanding.
+ */
+static int
+kauth_resolver_getwork(user_addr_t message)
+{
+       struct kauth_resolver_work *workp;
+       int             error;
+
+       KAUTH_RESOLVER_LOCK();
+       error = 0;
+       while ((workp = TAILQ_FIRST(&kauth_resolver_unsubmitted)) == NULL) {
+               thread_t thread = current_thread();
+               struct uthread *ut = get_bsdthread_info(thread);
+
+               ut->uu_kauth.message = message;
+               error = msleep0(&kauth_resolver_unsubmitted, kauth_resolver_mtx, PCATCH, "GRGetWork", 0, kauth_resolver_getwork_continue);
+               KAUTH_RESOLVER_UNLOCK();
+               return(error);
+       }
+       return kauth_resolver_getwork2(message);
+}
+
+
 /*
- * Return a result from userspace.
+ * kauth_resolver_complete
+ *
+ * Description:        Return a result from userspace.
+ *
+ * Parameters: message                         message from user space
+ *
+ * Returns:    0                               Success
+ *             EIO                             The resolver is dead
+ *     copyin:EFAULT                           Bad message from user space
  */
 static int
 kauth_resolver_complete(user_addr_t message)
@@ -471,7 +721,7 @@ static lck_mtx_t *kauth_identity_mtx;
 
 static struct kauth_identity *kauth_identity_alloc(uid_t uid, gid_t gid, guid_t *guidp, time_t guid_expiry,
     ntsid_t *ntsidp, time_t ntsid_expiry);
-static void    kauth_identity_register(struct kauth_identity *kip);
+static void    kauth_identity_register_and_free(struct kauth_identity *kip);
 static void    kauth_identity_updatecache(struct kauth_identity_extlookup *elp, struct kauth_identity *kip);
 static void    kauth_identity_lru(struct kauth_identity *kip);
 static int     kauth_identity_guid_expired(struct kauth_identity *kip);
@@ -481,6 +731,23 @@ static int kauth_identity_find_gid(gid_t gid, struct kauth_identity *kir);
 static int     kauth_identity_find_guid(guid_t *guidp, struct kauth_identity *kir);
 static int     kauth_identity_find_ntsid(ntsid_t *ntsid, struct kauth_identity *kir);
 
+
+/*
+ * kauth_identity_init
+ *
+ * Description:        Initialize the kernel side of the credential identity resolver
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (void)
+ *
+ * Notes:      Intialize the credential identity resolver for use; the
+ *             credential identity resolver is the KPI used to communicate
+ *             with a user space credential identity resolver daemon.
+ *
+ *             This function is called from kauth_init() in the file
+ *             kern_authorization.c.
+ */
 void
 kauth_identity_init(void)
 {
@@ -488,12 +755,24 @@ kauth_identity_init(void)
        kauth_identity_mtx = lck_mtx_alloc_init(kauth_lck_grp, 0/*LCK_ATTR_NULL*/);
 }
 
-static int
-kauth_identity_resolve(__unused struct kauth_identity_extlookup *el)
-{
-       return(kauth_resolver_submit(el));
-}
 
+/*
+ * kauth_identity_alloc
+ *
+ * Description:        Allocate and fill out a kauth_identity structure for
+ *             translation between {UID|GID}/GUID/NTSID
+ *
+ * Parameters: uid
+ *
+ * Returns:    NULL                            Insufficient memory to satisfy
+ *                                             the request
+ *             !NULL                           A pointer to the applocated
+ *                                             structure, filled in
+ *
+ * Notes:      It is illegal to translate between UID and GID; any given UUID
+ *             or NTSID can oly refer to an NTSIDE or UUID (respectively),
+ *             and *either* a UID *or* a GID, but not both.
+ */
 static struct kauth_identity *
 kauth_identity_alloc(uid_t uid, gid_t gid, guid_t *guidp, time_t guid_expiry, ntsid_t *ntsidp, time_t ntsid_expiry)
 {
@@ -526,17 +805,29 @@ kauth_identity_alloc(uid_t uid, gid_t gid, guid_t *guidp, time_t guid_expiry, nt
        return(kip);
 }
 
+
 /*
- * Register an association between identity tokens.
+ * kauth_identity_register_and_free
+ *
+ * Description:        Register an association between identity tokens.  The passed
+ *             'kip' is freed by this function.
+ *
+ * Parameters: kip                             Pointer to kauth_identity
+ *                                             structure to register
+ *
+ * Returns:    (void)
+ *
+ * Notes:      The memory pointer to by 'kip' is assumed to have been
+ *             previously allocated via kauth_identity_alloc().
  */
 static void
-kauth_identity_register(struct kauth_identity *kip)
+kauth_identity_register_and_free(struct kauth_identity *kip)
 {
        struct kauth_identity *ip;
 
        /*
-        * We search the cache for the UID listed in the incoming association.  If we
-        * already have an entry, the new information is merged.
+        * We search the cache for the UID listed in the incoming association.
+        * If we already have an entry, the new information is merged.
         */
        ip = NULL;
        KAUTH_IDENTITY_LOCK();
@@ -584,9 +875,22 @@ kauth_identity_register(struct kauth_identity *kip)
                FREE(ip, M_KAUTH);
 }
 
+
 /*
- * Given a lookup result, add any associations that we don't
- * currently have.
+ * kauth_identity_updatecache
+ *
+ * Description:        Given a lookup result, add any associations that we don't
+ *             currently have.
+ *
+ * Parameters: elp                             External lookup result from
+ *                                             user space daemon to kernel
+ *             rkip                            pointer to returned kauth
+ *                                             identity, or NULL
+ *
+ * Returns:    (void)
+ *
+ * Implicit returns:
+ *             *rkip                           Modified (if non-NULL)
  */
 static void
 kauth_identity_updatecache(struct kauth_identity_extlookup *elp, struct kauth_identity *rkip)
@@ -631,7 +935,7 @@ kauth_identity_updatecache(struct kauth_identity_extlookup *elp, struct kauth_id
                                if (rkip != NULL)
                                        *rkip = *kip;
                                KAUTH_DEBUG("CACHE - learned %d is " K_UUID_FMT, kip->ki_uid, K_UUID_ARG(kip->ki_guid));
-                               kauth_identity_register(kip);
+                               kauth_identity_register_and_free(kip);
                        }
                }
        }
@@ -671,20 +975,30 @@ kauth_identity_updatecache(struct kauth_identity_extlookup *elp, struct kauth_id
                                if (rkip != NULL)
                                        *rkip = *kip;
                                KAUTH_DEBUG("CACHE - learned %d is " K_UUID_FMT, kip->ki_uid, K_UUID_ARG(kip->ki_guid));
-                               kauth_identity_register(kip);
+                               kauth_identity_register_and_free(kip);
                        }
                }
        }
 
 }
 
+
 /*
- * Promote the entry to the head of the LRU, assumes the cache is locked.
+ * kauth_identity_lru
+ *
+ * Description:        Promote the entry to the head of the LRU, assumes the cache
+ *             is locked.
  *
- * This is called even if the entry has expired; typically an expired entry
- * that's been looked up is about to be revalidated, and having it closer to
- * the head of the LRU means finding it quickly again when the revalidation
- * comes through.
+ * Parameters: kip                             kauth identity to move to the
+ *                                             head of the LRU list, if it's
+ *                                             not already there
+ *
+ * Returns:    (void)
+ *
+ * Notes:      This is called even if the entry has expired; typically an
+ *             expired entry that's been looked up is about to be revalidated,
+ *             and having it closer to the head of the LRU means finding it
+ *             quickly again when the revalidation comes through.
  */
 static void
 kauth_identity_lru(struct kauth_identity *kip)
@@ -695,8 +1009,17 @@ kauth_identity_lru(struct kauth_identity *kip)
        }
 }
 
+
 /*
- * Handly lazy expiration of translations.
+ * kauth_identity_guid_expired
+ *
+ * Description:        Handle lazy expiration of GUID translations.
+ *
+ * Parameters: kip                             kauth identity to check for
+ *                                             GUID expiration
+ *
+ * Returns:    1                               Expired
+ *             0                               Not expired
  */
 static int
 kauth_identity_guid_expired(struct kauth_identity *kip)
@@ -708,6 +1031,18 @@ kauth_identity_guid_expired(struct kauth_identity *kip)
        return((kip->ki_guid_expiry <= tv.tv_sec) ? 1 : 0);
 }
 
+
+/*
+ * kauth_identity_ntsid_expired
+ *
+ * Description:        Handle lazy expiration of NTSID translations.
+ *
+ * Parameters: kip                             kauth identity to check for
+ *                                             NTSID expiration
+ *
+ * Returns:    1                               Expired
+ *             0                               Not expired
+ */
 static int
 kauth_identity_ntsid_expired(struct kauth_identity *kip)
 {
@@ -718,9 +1053,20 @@ kauth_identity_ntsid_expired(struct kauth_identity *kip)
        return((kip->ki_ntsid_expiry <= tv.tv_sec) ? 1 : 0);
 }
 
+
 /*
- * Search for an entry by UID.  Returns a copy of the entry, ENOENT if no valid
- * association exists for the UID.
+ * kauth_identity_find_uid
+ *
+ * Description: Search for an entry by UID
+ *
+ * Parameters: uid                             UID to find
+ *             kir                             Pointer to return area
+ *
+ * Returns:    0                               Found
+ *             ENOENT                          Not found
+ *
+ * Implicit returns:
+ *             *klr                            Modified, if found
  */
 static int
 kauth_identity_find_uid(uid_t uid, struct kauth_identity *kir)
@@ -731,6 +1077,7 @@ kauth_identity_find_uid(uid_t uid, struct kauth_identity *kir)
        TAILQ_FOREACH(kip, &kauth_identities, ki_link) {
                if ((kip->ki_valid & KI_VALID_UID) && (uid == kip->ki_uid)) {
                        kauth_identity_lru(kip);
+                       /* Copy via structure assignment */
                        *kir = *kip;
                        break;
                }
@@ -741,8 +1088,18 @@ kauth_identity_find_uid(uid_t uid, struct kauth_identity *kir)
 
 
 /*
- * Search for an entry by GID. Returns a copy of the entry, ENOENT if no valid
- * association exists for the GID.
+ * kauth_identity_find_uid
+ *
+ * Description: Search for an entry by GID
+ *
+ * Parameters: gid                             GID to find
+ *             kir                             Pointer to return area
+ *
+ * Returns:    0                               Found
+ *             ENOENT                          Not found
+ *
+ * Implicit returns:
+ *             *klr                            Modified, if found
  */
 static int
 kauth_identity_find_gid(uid_t gid, struct kauth_identity *kir)
@@ -753,6 +1110,7 @@ kauth_identity_find_gid(uid_t gid, struct kauth_identity *kir)
        TAILQ_FOREACH(kip, &kauth_identities, ki_link) {
                if ((kip->ki_valid & KI_VALID_GID) && (gid == kip->ki_gid)) {
                        kauth_identity_lru(kip);
+                       /* Copy via structure assignment */
                        *kir = *kip;
                        break;
                }
@@ -763,9 +1121,21 @@ kauth_identity_find_gid(uid_t gid, struct kauth_identity *kir)
 
 
 /*
- * Search for an entry by GUID. Returns a copy of the entry, ENOENT if no valid
- * association exists for the GUID.  Note that the association may be expired,
- * in which case the caller may elect to call out to userland to revalidate.
+ * kauth_identity_find_guid
+ *
+ * Description: Search for an entry by GUID
+ *
+ * Parameters: guidp                           Pointer to GUID to find
+ *             kir                             Pointer to return area
+ *
+ * Returns:    0                               Found
+ *             ENOENT                          Not found
+ *
+ * Implicit returns:
+ *             *klr                            Modified, if found
+ *
+ * Note:       The association may be expired, in which case the caller
+ *             may elect to call out to userland to revalidate.
  */
 static int
 kauth_identity_find_guid(guid_t *guidp, struct kauth_identity *kir)
@@ -776,6 +1146,7 @@ kauth_identity_find_guid(guid_t *guidp, struct kauth_identity *kir)
        TAILQ_FOREACH(kip, &kauth_identities, ki_link) {
                if ((kip->ki_valid & KI_VALID_GUID) && (kauth_guid_equal(guidp, &kip->ki_guid))) {
                        kauth_identity_lru(kip);
+                       /* Copy via structure assignment */
                        *kir = *kip;
                        break;
                }
@@ -784,10 +1155,23 @@ kauth_identity_find_guid(guid_t *guidp, struct kauth_identity *kir)
        return((kip == NULL) ? ENOENT : 0);
 }
 
+
 /*
- * Search for an entry by NT Security ID. Returns a copy of the entry, ENOENT if no valid
- * association exists for the SID.  Note that the association may be expired,
- * in which case the caller may elect to call out to userland to revalidate.
+ * kauth_identity_find_ntsid
+ *
+ * Description: Search for an entry by NTSID
+ *
+ * Parameters: ntsid                           Pointer to NTSID to find
+ *             kir                             Pointer to return area
+ *
+ * Returns:    0                               Found
+ *             ENOENT                          Not found
+ *
+ * Implicit returns:
+ *             *klr                            Modified, if found
+ *
+ * Note:       The association may be expired, in which case the caller
+ *             may elect to call out to userland to revalidate.
  */
 static int
 kauth_identity_find_ntsid(ntsid_t *ntsid, struct kauth_identity *kir)
@@ -798,6 +1182,7 @@ kauth_identity_find_ntsid(ntsid_t *ntsid, struct kauth_identity *kir)
        TAILQ_FOREACH(kip, &kauth_identities, ki_link) {
                if ((kip->ki_valid & KI_VALID_NTSID) && (kauth_ntsid_equal(ntsid, &kip->ki_ntsid))) {
                        kauth_identity_lru(kip);
+                       /* Copy via structure assignment */
                        *kir = *kip;
                        break;
                }
@@ -806,19 +1191,43 @@ kauth_identity_find_ntsid(ntsid_t *ntsid, struct kauth_identity *kir)
        return((kip == NULL) ? ENOENT : 0);
 }
 
+
 /*
  * GUID handling.
  */
 guid_t kauth_null_guid;
 
+
+/*
+ * kauth_guid_equal
+ *
+ * Description:        Determine the equality of two GUIDs
+ *
+ * Parameters: guid1                           Pointer to first GUID
+ *             guid2                           Pointer to second GUID
+ *
+ * Returns:    0                               If GUIDs are inequal
+ *             !0                              If GUIDs are equal
+ */
 int
 kauth_guid_equal(guid_t *guid1, guid_t *guid2)
 {
-       return(!bcmp(guid1, guid2, sizeof(*guid1)));
+       return(bcmp(guid1, guid2, sizeof(*guid1)) == 0);
 }
 
+
 /*
- * Look for well-known GUIDs.
+ * kauth_wellknown_guid
+ *
+ * Description:        Determine if a GUID is a well-known GUID
+ *
+ * Parameters: guid                            Pointer to GUID to check
+ *
+ * Returns:    KAUTH_WKG_NOT                   Not a wel known GUID
+ *             KAUTH_WKG_EVERYBODY             "Everybody"
+ *             KAUTH_WKG_NOBODY                "Nobody"
+ *             KAUTH_WKG_OWNER                 "Other"
+ *             KAUTH_WKG_GROUP                 "Group"
  */
 int
 kauth_wellknown_guid(guid_t *guid)
@@ -828,11 +1237,11 @@ kauth_wellknown_guid(guid_t *guid)
        /*
         * All WKGs begin with the same 12 bytes.
         */
-       if (!bcmp((void *)guid, fingerprint, 12)) {
+       if (bcmp((void *)guid, fingerprint, 12) == 0) {
                /*
-                * The final 4 bytes are our code.
+                * The final 4 bytes are our code (in network byte order).
                 */
-               code = *(u_int32_t *)&guid->g_guid[12];
+               code = OSSwapHostToBigInt32(*(u_int32_t *)&guid->g_guid[12]);
                switch(code) {
                case 0x0000000c:
                        return(KAUTH_WKG_EVERYBODY);
@@ -849,7 +1258,15 @@ kauth_wellknown_guid(guid_t *guid)
 
 
 /*
- * NT Security Identifier handling.
+ * kauth_ntsid_equal
+ *
+ * Description:        Determine the equality of two NTSIDs (NT Security Identifiers) 
+ *
+ * Paramters:  sid1                            Pointer to first NTSID
+ *             sid2                            Pointer to second NTSID
+ *
+ * Returns:    0                               If GUIDs are inequal
+ *             !0                              If GUIDs are equal
  */
 int
 kauth_ntsid_equal(ntsid_t *sid1, ntsid_t *sid2)
@@ -857,11 +1274,12 @@ kauth_ntsid_equal(ntsid_t *sid1, ntsid_t *sid2)
        /* check sizes for equality, also sanity-check size while we're at it */
        if ((KAUTH_NTSID_SIZE(sid1) == KAUTH_NTSID_SIZE(sid2)) &&
            (KAUTH_NTSID_SIZE(sid1) <= sizeof(*sid1)) &&
-           !bcmp(sid1, sid2, KAUTH_NTSID_SIZE(sid1)))
+           bcmp(sid1, sid2, KAUTH_NTSID_SIZE(sid1)) == 0)
                return(1);
        return(0);
 }
 
+
 /*
  * Identity KPI
  *
@@ -877,8 +1295,96 @@ kauth_ntsid_equal(ntsid_t *sid1, ntsid_t *sid2)
 
 static int     kauth_cred_cache_lookup(int from, int to, void *src, void *dst);
 
+
+/*
+ * kauth_cred_change_egid
+ *
+ * Description:        Set EGID by changing the first element of cr_groups for the
+ *             passed credential; if the new EGID exists in the list of
+ *             groups already, then rotate the old EGID into its position,
+ *             otherwise replace it
+ *
+ * Parameters: cred                    Pointer to the credential to modify
+ *             new_egid                The new EGID to set
+ *
+ * Returns:    0                       The egid did not displace a member of
+ *                                     the supplementary group list
+ *             1                       The egid being set displaced a member
+ *                                     of the supplementary groups list
+ *
+ * Note:       Utility function; internal use only because of locking.
+ *
+ *             This function operates on the credential passed; the caller
+ *             must operate either on a newly allocated credential (one for
+ *             which there is no hash cache reference and no externally
+ *             visible pointer reference), or a template credential.
+ */
+static int
+kauth_cred_change_egid(kauth_cred_t cred, gid_t new_egid)
+{
+       int     i;
+       int     displaced = 1;
+#if radar_4600026
+       int     is_member;
+#endif /* radar_4600026 */
+       gid_t   old_egid = cred->cr_groups[0];
+
+       /* Ignoring the first entry, scan for a match for the new egid */
+       for (i = 1; i < cred->cr_ngroups; i++) {
+               /*
+                * If we find a match, swap them so we don't lose overall
+                * group information
+                */
+               if (cred->cr_groups[i] == new_egid) {
+                       cred->cr_groups[i] = old_egid;
+                       DEBUG_CRED_CHANGE("kauth_cred_change_egid: unset displaced\n");
+                       displaced = 0;
+                       break;
+               }
+       }
+
+#if radar_4600026
+#error Fix radar 4600026 first!!!
+
+/*
+This is correct for memberd behaviour, but incorrect for POSIX; to address
+this, we would need to automatically opt-out any SUID/SGID binary, and force
+it to use initgroups to opt back in.  We take the approach of considering it
+opt'ed out in any group of 16 displacement instead, since it's a much more
+conservative approach (i.e. less likely to cause things to break).
+*/
+
+       /*
+        * If we displaced a member of the supplementary groups list of the
+        * credential, and we have not opted out of memberd, then if memberd
+        * says that the credential is a member of the group, then it has not
+        * actually been displaced.
+        *
+        * NB:  This is typically a cold code path.
+        */
+       if (displaced && !(cred->cr_flags & CRF_NOMEMBERD) &&
+           kauth_cred_ismember_gid(cred, new_egid, &is_member) == 0 &&
+           is_member) {
+               displaced = 0;
+               DEBUG_CRED_CHANGE("kauth_cred_change_egid: reset displaced\n");
+       }
+#endif /* radar_4600026 */
+
+       /* set the new EGID into the old spot */
+       cred->cr_groups[0] = new_egid;
+
+       return (displaced);
+}
+
+
 /*
- * Fetch UID from credential.
+ * kauth_cred_getuid
+ *
+ * Description:        Fetch UID from credential
+ *
+ * Parameters: cred                            Credential to examine
+ *
+ * Returns:    (uid_t)                         UID associated with credential
  */
 uid_t
 kauth_cred_getuid(kauth_cred_t cred)
@@ -887,8 +1393,15 @@ kauth_cred_getuid(kauth_cred_t cred)
        return(cred->cr_uid);
 }
 
+
 /*
- * Fetch GID from credential.
+ * kauth_cred_getgid
+ *
+ * Description:        Fetch GID from credential
+ *
+ * Parameters: cred                            Credential to examine
+ *
+ * Returns:    (gid_t)                         GID associated with credential
  */
 uid_t
 kauth_cred_getgid(kauth_cred_t cred)
@@ -897,8 +1410,20 @@ kauth_cred_getgid(kauth_cred_t cred)
        return(cred->cr_gid);
 }
 
+
 /*
- * Fetch UID from GUID.
+ * kauth_cred_guid2uid
+ *
+ * Description:        Fetch UID from GUID
+ *
+ * Parameters: guidp                           Pointer to GUID to examine
+ *             uidp                            Pointer to buffer for UID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *uidp                           Modified, if successful
  */
 int
 kauth_cred_guid2uid(guid_t *guidp, uid_t *uidp)
@@ -906,8 +1431,20 @@ kauth_cred_guid2uid(guid_t *guidp, uid_t *uidp)
        return(kauth_cred_cache_lookup(KI_VALID_GUID, KI_VALID_UID, guidp, uidp));
 }
 
+
 /*
- * Fetch GID from GUID.
+ * kauth_cred_guid2gid
+ *
+ * Description:        Fetch GID from GUID
+ *
+ * Parameters: guidp                           Pointer to GUID to examine
+ *             gidp                            Pointer to buffer for GID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *gidp                           Modified, if successful
  */
 int
 kauth_cred_guid2gid(guid_t *guidp, gid_t *gidp)
@@ -915,8 +1452,20 @@ kauth_cred_guid2gid(guid_t *guidp, gid_t *gidp)
        return(kauth_cred_cache_lookup(KI_VALID_GUID, KI_VALID_GID, guidp, gidp));
 }
 
+
 /*
- * Fetch UID from NT SID.
+ * kauth_cred_ntsid2uid
+ *
+ * Description:        Fetch UID from NTSID
+ *
+ * Parameters: sidp                            Pointer to NTSID to examine
+ *             uidp                            Pointer to buffer for UID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *uidp                           Modified, if successful
  */
 int
 kauth_cred_ntsid2uid(ntsid_t *sidp, uid_t *uidp)
@@ -924,8 +1473,20 @@ kauth_cred_ntsid2uid(ntsid_t *sidp, uid_t *uidp)
        return(kauth_cred_cache_lookup(KI_VALID_NTSID, KI_VALID_UID, sidp, uidp));
 }
 
+
 /*
- * Fetch GID from NT SID.
+ * kauth_cred_ntsid2gid
+ *
+ * Description:        Fetch GID from NTSID
+ *
+ * Parameters: sidp                            Pointer to NTSID to examine
+ *             gidp                            Pointer to buffer for GID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *gidp                           Modified, if successful
  */
 int
 kauth_cred_ntsid2gid(ntsid_t *sidp, gid_t *gidp)
@@ -933,8 +1494,20 @@ kauth_cred_ntsid2gid(ntsid_t *sidp, gid_t *gidp)
        return(kauth_cred_cache_lookup(KI_VALID_NTSID, KI_VALID_GID, sidp, gidp));
 }
 
+
 /*
- * Fetch GUID from NT SID.
+ * kauth_cred_ntsid2guid
+ *
+ * Description:        Fetch GUID from NTSID
+ *
+ * Parameters: sidp                            Pointer to NTSID to examine
+ *             guidp                           Pointer to buffer for GUID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *guidp                          Modified, if successful
  */
 int
 kauth_cred_ntsid2guid(ntsid_t *sidp, guid_t *guidp)
@@ -942,8 +1515,20 @@ kauth_cred_ntsid2guid(ntsid_t *sidp, guid_t *guidp)
        return(kauth_cred_cache_lookup(KI_VALID_NTSID, KI_VALID_GUID, sidp, guidp));
 }
 
+
 /*
- * Fetch GUID from UID.
+ * kauth_cred_uid2guid
+ *
+ * Description:        Fetch GUID from UID
+ *
+ * Parameters: uid                             UID to examine
+ *             guidp                           Pointer to buffer for GUID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *guidp                          Modified, if successful
  */
 int
 kauth_cred_uid2guid(uid_t uid, guid_t *guidp)
@@ -951,8 +1536,20 @@ kauth_cred_uid2guid(uid_t uid, guid_t *guidp)
        return(kauth_cred_cache_lookup(KI_VALID_UID, KI_VALID_GUID, &uid, guidp));
 }
 
+
 /*
- * Fetch user GUID from credential.
+ * kauth_cred_getguid
+ *
+ * Description:        Fetch GUID from credential
+ *
+ * Parameters: cred                            Credential to examine
+ *             guidp                           Pointer to buffer for GUID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *guidp                          Modified, if successful
  */
 int
 kauth_cred_getguid(kauth_cred_t cred, guid_t *guidp)
@@ -961,17 +1558,41 @@ kauth_cred_getguid(kauth_cred_t cred, guid_t *guidp)
        return(kauth_cred_uid2guid(kauth_cred_getuid(cred), guidp));
 }
 
+
 /*
- * Fetch GUID from GID.
- */
-int
+ * kauth_cred_getguid
+ *
+ * Description:        Fetch GUID from GID
+ *
+ * Parameters: gid                             GID to examine
+ *             guidp                           Pointer to buffer for GUID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *guidp                          Modified, if successful
+ */
+int
 kauth_cred_gid2guid(gid_t gid, guid_t *guidp)
 {
        return(kauth_cred_cache_lookup(KI_VALID_GID, KI_VALID_GUID, &gid, guidp));
 }
 
+
 /*
- * Fetch NT SID from UID.
+ * kauth_cred_uid2ntsid
+ *
+ * Description:        Fetch NTSID from UID
+ *
+ * Parameters: uid                             UID to examine
+ *             sidp                            Pointer to buffer for NTSID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *sidp                           Modified, if successful
  */
 int
 kauth_cred_uid2ntsid(uid_t uid, ntsid_t *sidp)
@@ -979,8 +1600,20 @@ kauth_cred_uid2ntsid(uid_t uid, ntsid_t *sidp)
        return(kauth_cred_cache_lookup(KI_VALID_UID, KI_VALID_NTSID, &uid, sidp));
 }
 
+
 /*
- * Fetch NT SID from credential.
+ * kauth_cred_getntsid
+ *
+ * Description:        Fetch NTSID from credential
+ *
+ * Parameters: cred                            Credential to examine
+ *             sidp                            Pointer to buffer for NTSID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *sidp                           Modified, if successful
  */
 int
 kauth_cred_getntsid(kauth_cred_t cred, ntsid_t *sidp)
@@ -989,8 +1622,20 @@ kauth_cred_getntsid(kauth_cred_t cred, ntsid_t *sidp)
        return(kauth_cred_uid2ntsid(kauth_cred_getuid(cred), sidp));
 }
 
+
 /*
- * Fetch NT SID from GID.
+ * kauth_cred_gid2ntsid
+ *
+ * Description:        Fetch NTSID from GID
+ *
+ * Parameters: gid                             GID to examine
+ *             sidp                            Pointer to buffer for NTSID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *sidp                           Modified, if successful
  */
 int
 kauth_cred_gid2ntsid(gid_t gid, ntsid_t *sidp)
@@ -998,8 +1643,20 @@ kauth_cred_gid2ntsid(gid_t gid, ntsid_t *sidp)
        return(kauth_cred_cache_lookup(KI_VALID_GID, KI_VALID_NTSID, &gid, sidp));
 }
 
+
 /*
- * Fetch NT SID from GUID.
+ * kauth_cred_guid2ntsid
+ *
+ * Description:        Fetch NTSID from GUID
+ *
+ * Parameters: guidp                           Pointer to GUID to examine
+ *             sidp                            Pointer to buffer for NTSID
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_cache_lookup:EINVAL
+ *
+ * Implicit returns:
+ *             *sidp                           Modified, if successful
  */
 int
 kauth_cred_guid2ntsid(guid_t *guidp, ntsid_t *sidp)
@@ -1008,9 +1665,22 @@ kauth_cred_guid2ntsid(guid_t *guidp, ntsid_t *sidp)
 }
 
 
-
 /*
- * Lookup a translation in the cache.
+ * kauth_cred_cache_lookup
+ *
+ * Description:        Lookup a translation in the cache; if one is not found, and
+ *             the attempt was not fatal, submit the request to the resolver
+ *             instead, and wait for it to complete or be aborted.
+ *
+ * Parameters: from                            Identity information we have
+ *             to                              Identity information we want
+ *             src                             Pointer to buffer containing
+ *                                             the source identity
+ *             dst                             Pointer to buffer to receive
+ *                                             the target identity
+ *
+ * Returns:    0                               Success
+ *             EINVAL                          Unknown source identity type
  */
 static int
 kauth_cred_cache_lookup(int from, int to, void *src, void *dst)
@@ -1047,6 +1717,7 @@ kauth_cred_cache_lookup(int from, int to, void *src, void *dst)
        if (error != 0) {
                /* any other error is fatal */
                if (error != ENOENT) {
+                       /* XXX bogus check - this is not possible */
                        KAUTH_DEBUG("CACHE - cache search error %d", error);
                        return(error);
                }
@@ -1087,16 +1758,19 @@ kauth_cred_cache_lookup(int from, int to, void *src, void *dst)
                                goto found;
                        }
                        /*
-                        * We leave ki_valid set here; it contains a translation but the TTL has
-                        * expired.  If we can't get a result from the resolver, we will
-                        * use it as a better-than nothing alternative.
+                        * We leave ki_valid set here; it contains a
+                        * translation but the TTL has expired.  If we can't
+                        * get a result from the resolver, we will use it as
+                        * a better-than nothing alternative.
                         */
                        KAUTH_DEBUG("CACHE - expired entry found");
                }
        }
 
        /*
-        * Call the resolver.  We ask for as much data as we can get.
+        * We failed to find a cache entry; call the resolver.
+        *
+        * Note:        We ask for as much data as we can get.
         */
        switch(from) {
        case KI_VALID_UID:
@@ -1133,13 +1807,13 @@ kauth_cred_cache_lookup(int from, int to, void *src, void *dst)
            KAUTH_EXTLOOKUP_WANT_UGUID | KAUTH_EXTLOOKUP_WANT_GGUID |
            KAUTH_EXTLOOKUP_WANT_USID | KAUTH_EXTLOOKUP_WANT_GSID;
        KAUTH_DEBUG("CACHE - calling resolver for %x", el.el_flags);
-       error = kauth_identity_resolve(&el);
+       error = kauth_resolver_submit(&el);
        KAUTH_DEBUG("CACHE - resolver returned %d", error);
        /* was the lookup successful? */
        if (error == 0) {
                /*
-                * Save the results from the lookup - may have other information even if we didn't
-                * get a guid.
+                * Save the results from the lookup - may have other
+                * information even if we didn't get a guid.
                 */
                kauth_identity_updatecache(&el, &ki);
        }
@@ -1199,6 +1873,22 @@ static int       kauth_groups_expired(struct kauth_group_membership *gm);
 static void    kauth_groups_lru(struct kauth_group_membership *gm);
 static void    kauth_groups_updatecache(struct kauth_identity_extlookup *el);
 
+
+/*
+ * kauth_groups_init
+ *
+ * Description:        Initialize the groups cache
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (void)
+ *
+ * Notes:      Intialize the groups cache for use; the group cache is used
+ *             to avoid unnecessary calls out to user space.
+ *
+ *             This function is called from kauth_init() in the file
+ *             kern_authorization.c.
+ */
 void
 kauth_groups_init(void)
 {
@@ -1206,6 +1896,18 @@ kauth_groups_init(void)
        kauth_groups_mtx = lck_mtx_alloc_init(kauth_lck_grp, 0/*LCK_ATTR_NULL*/);
 }
 
+
+/*
+ * kauth_groups_expired
+ *
+ * Description:        Handle lazy expiration of group membership cache entries
+ *
+ * Parameters: gm                              group membership entry to
+ *                                             check for expiration
+ *
+ * Returns:    1                               Expired
+ *             0                               Not expired
+ */
 static int
 kauth_groups_expired(struct kauth_group_membership *gm)
 {
@@ -1215,6 +1917,24 @@ kauth_groups_expired(struct kauth_group_membership *gm)
        return((gm->gm_expiry <= tv.tv_sec) ? 1 : 0);
 }
 
+
+/*
+ * kauth_groups_lru
+ *
+ * Description:        Promote the entry to the head of the LRU, assumes the cache
+ *             is locked.
+ *
+ * Parameters: kip                             group membership entry to move
+ *                                             to the head of the LRU list,
+ *                                             if it's not already there
+ *
+ * Returns:    (void)
+ *
+ * Notes:      This is called even if the entry has expired; typically an
+ *             expired entry that's been looked up is about to be revalidated,
+ *             and having it closer to the head of the LRU means finding it
+ *             quickly again when the revalidation comes through.
+ */
 static void
 kauth_groups_lru(struct kauth_group_membership *gm)
 {
@@ -1224,6 +1944,20 @@ kauth_groups_lru(struct kauth_group_membership *gm)
        }
 }
 
+
+/*
+ * kauth_groups_updatecache
+ *
+ * Description:        Given a lookup result, add any group cache associations that
+ *             we don't currently have.
+ *
+ * Parameters: elp                             External lookup result from
+ *                                             user space daemon to kernel
+ *             rkip                            pointer to returned kauth
+ *                                             identity, or NULL
+ *
+ * Returns:    (void)
+ */
 static void
 kauth_groups_updatecache(struct kauth_identity_extlookup *el)
 {
@@ -1238,7 +1972,10 @@ kauth_groups_updatecache(struct kauth_identity_extlookup *el)
 
        microuptime(&tv);
 
-       /* search for an existing record for this association before inserting */
+       /*
+        * Search for an existing record for this association before inserting
+        * a new one; if we find one, update it instead of creating a new one
+        */
        KAUTH_GROUPS_LOCK();
        TAILQ_FOREACH(gm, &kauth_groups, gm_link) {
                if ((el->el_uid == gm->gm_uid) &&
@@ -1273,10 +2010,10 @@ kauth_groups_updatecache(struct kauth_identity_extlookup *el)
        }               
 
        /*
-        * Insert the new entry.  Note that it's possible to race ourselves here
-        * and end up with duplicate entries in the list.  Wasteful, but harmless
-        * since the first into the list will never be looked up, and thus will
-        * eventually just fall off the end.
+        * Insert the new entry.  Note that it's possible to race ourselves
+        * here and end up with duplicate entries in the list.  Wasteful, but
+        * harmless since the first into the list will never be looked up,
+        * and thus will eventually just fall off the end.
         */
        KAUTH_GROUPS_LOCK();
        TAILQ_INSERT_HEAD(&kauth_groups, gm, gm_link);
@@ -1294,11 +2031,39 @@ kauth_groups_updatecache(struct kauth_identity_extlookup *el)
                FREE(gm, M_KAUTH);
 }
 
+
 /*
  * Group membership KPI
  */
+
 /*
- * This function guarantees not to modify resultp when returning an error.
+ * kauth_cred_ismember_gid
+ *
+ * Description:        Given a credential and a GID, determine if the GID is a member
+ *             of one of the supplementary groups associated with the given
+ *             credential
+ *
+ * Parameters: cred                            Credential to check in
+ *             gid                             GID to check for membership
+ *             resultp                         Pointer to int to contain the
+ *                                             result of the call
+ *
+ * Returns:    0                               Success
+ *             ENOENT                          Could not proform lookup
+ *     kauth_resolver_submit:EWOULDBLOCK
+ *     kauth_resolver_submit:EINTR
+ *     kauth_resolver_submit:ENOMEM
+ *     kauth_resolver_submit:???               Unlikely error from user space
+ *
+ * Implicit returns:
+ *             *resultp (modified)     1       Is member
+ *                                     0       Is not member
+ *
+ * Notes:      This function guarantees not to modify resultp when returning
+ *             an error.
+ *
+ *             This function effectively checkes the EGID as well, since the
+ *             EGID is cr_groups[0] as an implementation detail.
  */
 int
 kauth_cred_ismember_gid(kauth_cred_t cred, gid_t gid, int *resultp)
@@ -1331,8 +2096,8 @@ kauth_cred_ismember_gid(kauth_cred_t cred, gid_t gid, int *resultp)
                
        
        /*
-        * If the resolver hasn't checked in yet, we are early in the boot phase and
-        * the local group list is complete and authoritative.
+        * If the resolver hasn't checked in yet, we are early in the boot
+        * phase and the local group list is complete and authoritative.
         */
        if (!kauth_resolver_registered) {
                *resultp = 0;
@@ -1368,7 +2133,8 @@ kauth_cred_ismember_gid(kauth_cred_t cred, gid_t gid, int *resultp)
        el.el_flags = KAUTH_EXTLOOKUP_VALID_UID | KAUTH_EXTLOOKUP_VALID_GID | KAUTH_EXTLOOKUP_WANT_MEMBERSHIP;
        el.el_uid = cred->cr_gmuid;
        el.el_gid = gid;
-       error = kauth_identity_resolve(&el);
+       el.el_member_valid = 0;         /* XXX set by resolver? */
+       error = kauth_resolver_submit(&el);
        if (error != 0)
                return(error);
        /* save the results from the lookup */
@@ -1383,9 +2149,30 @@ kauth_cred_ismember_gid(kauth_cred_t cred, gid_t gid, int *resultp)
        return(ENOENT);
 }
 
+
 /*
- * Determine whether the supplied credential is a member of the
- * group nominated by GUID.
+ * kauth_cred_ismember_guid
+ *
+ * Description:        Determine whether the supplied credential is a member of the
+ *             group nominated by GUID.
+ *
+ * Parameters: cred                            Credential to check in
+ *             guidp                           Pointer to GUID whose group
+ *                                             we are testing for membership
+ *             resultp                         Pointer to int to contain the
+ *                                             result of the call
+ *
+ * Returns:    0                               Success
+ *     kauth_cred_guid2gid:EINVAL
+ *     kauth_cred_ismember_gid:ENOENT
+ *     kauth_cred_ismember_gid:EWOULDBLOCK
+ *     kauth_cred_ismember_gid:EINTR
+ *     kauth_cred_ismember_gid:ENOMEM
+ *     kauth_cred_ismember_gid:???             Unlikely error from user space
+ *
+ * Implicit returns:
+ *             *resultp (modified)     1       Is member
+ *                                     0       Is not member
  */
 int
 kauth_cred_ismember_guid(kauth_cred_t cred, guid_t *guidp, int *resultp)
@@ -1421,7 +2208,86 @@ kauth_cred_ismember_guid(kauth_cred_t cred, guid_t *guidp, int *resultp)
 }
 
 /*
- * Fast replacement for issuser()
+ * kauth_cred_gid_subset
+ *
+ * Description:        Given two credentials, determine if all GIDs associated with 
+ *             the first are also associated with the second
+ *
+ * Parameters: cred1                           Credential to check for
+ *             cred2                           Credential to check in
+ *             resultp                         Pointer to int to contain the
+ *                                             result of the call
+ *
+ * Returns:    0                               Success
+ *             non-zero                        See kauth_cred_ismember_gid for
+ *                                             error codes
+ *
+ * Implicit returns:
+ *             *resultp (modified)     1       Is subset
+ *                                     0       Is not subset
+ *
+ * Notes:      This function guarantees not to modify resultp when returning
+ *             an error.
+ */
+int    
+kauth_cred_gid_subset(kauth_cred_t cred1, kauth_cred_t cred2, int *resultp)
+{
+       int i, err, res = 1;
+       gid_t gid;
+
+       /* First, check the local list of groups */
+       for (i = 0; i < cred1->cr_ngroups; i++) {
+               gid = cred1->cr_groups[i];
+               if ((err = kauth_cred_ismember_gid(cred2, gid, &res)) != 0) {
+                       return err;
+               }
+
+               if (!res && gid != cred2->cr_rgid && gid != cred2->cr_svgid) {
+                       *resultp = 0;
+                       return 0;
+               }
+       }
+
+       /* Check real gid */
+       if ((err = kauth_cred_ismember_gid(cred2, cred1->cr_rgid, &res)) != 0) {
+               return err;
+       }
+
+       if (!res && cred1->cr_rgid != cred2->cr_rgid &&
+                       cred1->cr_rgid != cred2->cr_svgid) {
+               *resultp = 0;
+               return 0;
+       }
+
+       /* Finally, check saved gid */
+       if ((err = kauth_cred_ismember_gid(cred2, cred1->cr_svgid, &res)) != 0){
+               return err;
+       }
+
+       if (!res && cred1->cr_svgid != cred2->cr_rgid &&
+                       cred1->cr_svgid != cred2->cr_svgid) {
+               *resultp = 0;
+               return 0;
+       }
+
+       *resultp = 1;
+       return 0;
+}
+
+
+/*
+ * kauth_cred_issuser
+ *
+ * Description:        Fast replacement for issuser()
+ *
+ * Parameters: cred                            Credential to check for super
+ *                                             user privileges
+ *
+ * Returns:    0                               Not super user
+ *             !0                              Is super user
+ *
+ * Notes:      This function uses a magic number which is not a manifest
+ *             constant; this is bad practice.
  */
 int
 kauth_cred_issuser(kauth_cred_t cred)
@@ -1429,6 +2295,7 @@ kauth_cred_issuser(kauth_cred_t cred)
        return(cred->cr_uid == 0);
 }
 
+
 /*
  * Credential KPI
  */
@@ -1443,6 +2310,38 @@ static lck_mtx_t *kauth_cred_hash_mtx;
 #define KAUTH_CRED_HASH_LOCK_ASSERT()
 #endif /* !KAUTH_CRED_HASH_DEBUG */
 
+
+/*
+ * kauth_cred_init
+ *
+ * Description:        Initialize the credential hash cache
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (void)
+ *
+ * Notes:      Intialize the credential hash cache for use; the credential
+ *             hash cache is used convert duplicate credentials into a
+ *             single reference counted credential in order to save wired
+ *             kernel memory.  In practice, this generally means a desktop
+ *             system runs with a few tens of credentials, instead of one
+ *             per process, one per thread, one per vnode cache entry, and
+ *             so on.  This generally results in savings of 200K or more
+ *             (potentially much more on server systems).
+ *
+ *             The hash cache internally has a reference on the credential
+ *             for itself as a means of avoiding a reclaim race for a
+ *             credential in the process of having it's last non-hash
+ *             reference released.  This would otherwise result in the
+ *             possibility of a freed credential that was still in uses due
+ *             a race.  This use is protected by the KAUTH_CRED_HASH_LOCK.
+ *
+ *             On final release, the hash reference is droped, and the
+ *             credential is freed back to the system.
+ *
+ *             This function is called from kauth_init() in the file
+ *             kern_authorization.c.
+ */
 void
 kauth_cred_init(void)
 {
@@ -1455,13 +2354,23 @@ kauth_cred_init(void)
        MALLOC(kauth_cred_table_anchor, struct kauth_cred_entry_head *, 
                        (sizeof(struct kauth_cred_entry_head) * kauth_cred_table_size), 
                        M_KAUTH, M_WAITOK | M_ZERO);
+       if (kauth_cred_table_anchor == NULL)
+               panic("startup: kauth_cred_init");
        for (i = 0; i < kauth_cred_table_size; i++) {
                TAILQ_INIT(&kauth_cred_table_anchor[i]);
        }
 }
 
+
 /*
- * Return the current thread's effective UID.
+ * kauth_getuid
+ *
+ * Description:        Get the current thread's effective UID.
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (uid_t)                         The effective UID of the
+ *                                             current thread
  */
 uid_t
 kauth_getuid(void)
@@ -1469,8 +2378,16 @@ kauth_getuid(void)
        return(kauth_cred_get()->cr_uid);
 }
 
+
 /*
- * Return the current thread's real UID.
+ * kauth_getruid
+ *
+ * Description:        Get the current thread's real UID.
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (uid_t)                         The real UID of the current
+ *                                             thread
  */
 uid_t
 kauth_getruid(void)
@@ -1478,8 +2395,16 @@ kauth_getruid(void)
        return(kauth_cred_get()->cr_ruid);
 }
 
+
 /*
- * Return the current thread's effective GID.
+ * kauth_getgid
+ *
+ * Description:        Get the current thread's effective GID.
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (gid_t)                         The effective GID of the
+ *                                             current thread
  */
 gid_t
 kauth_getgid(void)
@@ -1487,8 +2412,16 @@ kauth_getgid(void)
        return(kauth_cred_get()->cr_groups[0]);
 }
 
+
 /*
- * Return the current thread's real GID.
+ * kauth_getgid
+ *
+ * Description:        Get the current thread's real GID.
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (gid_t)                         The real GID of the current
+ *                                             thread
  */
 gid_t
 kauth_getrgid(void)
@@ -1496,10 +2429,28 @@ kauth_getrgid(void)
        return(kauth_cred_get()->cr_rgid);
 }
 
+
 /*
- * Returns a pointer to the current thread's credential, does not take a
- * reference (so the caller must not do anything that would let the thread's
- * credential change while using the returned value).
+ * kauth_cred_get
+ *
+ * Description:        Returns a pointer to the current thread's credential
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (kauth_cred_t)                  Pointer to the current thread's
+ *                                             credential
+ *
+ * Notes:      This function does not take a reference; because of this, the
+ *             caller MUST NOT do anything that would let the thread's
+ *             credential change while using the returned value, without
+ *             first explicitly taking their own reference.
+ *
+ *             If a caller intends to take a reference on the resulting
+ *             credential pointer from calling this function, it is strongly
+ *             recommended that the caller use kauth_cred_get_with_ref()
+ *             instead, to protect against any future changes to the cred
+ *             locking protocols; such changes could otherwise potentially
+ *             introduce race windows in the callers code.
  */
 kauth_cred_t
 kauth_cred_get(void)
@@ -1512,9 +2463,11 @@ kauth_cred_get(void)
        if (uthread == NULL)
                panic("thread wants credential but has no BSD thread info");
        /*
-        * We can lazy-bind credentials to threads, as long as their processes have them.
-        * If we later inline this function, the code in this block should probably be
-        * called out in a function.
+        * We can lazy-bind credentials to threads, as long as their processes
+        * have them.
+        *
+        * XXX If we later inline this function, the code in this block
+        * XXX should probably be called out in a function.
         */
        if (uthread->uu_ucred == NOCRED) {
                if ((p = (proc_t) get_bsdtask_info(get_threadtask(current_thread()))) == NULL)
@@ -1524,8 +2477,60 @@ kauth_cred_get(void)
        return(uthread->uu_ucred);
 }
 
+
+/*
+ * kauth_cred_uthread_update
+ *
+ * Description:        Given a uthread, a proc, and whether or not the proc is locked,
+ *             late-bind the uthread cred to the proc cred.
+ *
+ * Parameters: uthread_t                       The uthread to update
+ *             proc_t                          The process to update to
+ *
+ * Returns:    (void)
+ *
+ * Notes:      This code is common code called from system call or trap entry
+ *             in the case that the process thread may have been changed
+ *             since the last time the thread entered the kernel.  It is
+ *             generally only called with the current uthread and process as
+ *             parameters.
+ */
+void
+kauth_cred_uthread_update(uthread_t uthread, proc_t proc)
+{
+       if (uthread->uu_ucred != proc->p_ucred &&
+           (uthread->uu_flag & UT_SETUID) == 0) {
+               kauth_cred_t old = uthread->uu_ucred;
+               uthread->uu_ucred = kauth_cred_proc_ref(proc);
+               if (IS_VALID_CRED(old))
+                       kauth_cred_unref(&old);
+       }
+}
+
+
 /*
- * Returns a pointer to the current thread's credential, takes a reference.
+ * kauth_cred_get_with_ref
+ *
+ * Description:        Takes a reference on the current thread's credential, and then
+ *             returns a pointer to it to the caller.
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (kauth_cred_t)                  Pointer to the current thread's
+ *                                             newly referenced credential
+ *
+ * Notes:      This function takes a reference on the credential before
+ *             returning it to the caller.
+ *
+ *             It is the responsibility of the calling code to release this
+ *             reference when the credential is no longer in use.
+ *
+ *             Since the returned reference may be a persistent reference
+ *             (e.g. one cached in another data structure with a lifetime
+ *             longer than the calling function), this release may be delayed
+ *             until such time as the persistent reference is to be destroyed.
+ *             An example of this would be the per vnode credential cache used
+ *             to accelerate lookup operations.
  */
 kauth_cred_t
 kauth_cred_get_with_ref(void)
@@ -1541,9 +2546,11 @@ kauth_cred_get_with_ref(void)
                panic("%s - thread wants credential but has no BSD process", __FUNCTION__);
 
        /*
-        * We can lazy-bind credentials to threads, as long as their processes have them.
-        * If we later inline this function, the code in this block should probably be
-        * called out in a function.
+        * We can lazy-bind credentials to threads, as long as their processes
+        * have them.
+        *
+        * XXX If we later inline this function, the code in this block
+        * XXX should probably be called out in a function.
         */
        if (uthread->uu_ucred == NOCRED) {
                /* take reference for new cred in thread */
@@ -1554,8 +2561,35 @@ kauth_cred_get_with_ref(void)
        return(uthread->uu_ucred);
 }
 
+
 /*
- * Returns a pointer to the given process's credential, takes a reference.
+ * kauth_cred_proc_ref
+ *
+ * Description:        Takes a reference on the current process's credential, and
+ *             then returns a pointer to it to the caller.
+ *
+ * Parameters: procp                           Process whose credential we
+ *                                             intend to take a reference on
+ *
+ * Returns:    (kauth_cred_t)                  Pointer to the process's
+ *                                             newly referenced credential
+ *
+ * Locks:      PROC_LOCK is held before taking the reference and released
+ *             after the refeence is taken to protect the p_ucred field of
+ *             the process referred to by procp.
+ *
+ * Notes:      This function takes a reference on the credential before
+ *             returning it to the caller.
+ *
+ *             It is the responsibility of the calling code to release this
+ *             reference when the credential is no longer in use.
+ *
+ *             Since the returned reference may be a persistent reference
+ *             (e.g. one cached in another data structure with a lifetime
+ *             longer than the calling function), this release may be delayed
+ *             until such time as the persistent reference is to be destroyed.
+ *             An example of this would be the per vnode credential cache used
+ *             to accelerate lookup operations.
  */
 kauth_cred_t
 kauth_cred_proc_ref(proc_t procp)
@@ -1569,16 +2603,55 @@ kauth_cred_proc_ref(proc_t procp)
        return(cred);
 }
 
+
 /*
- * Allocates a new credential.
+ * kauth_cred_alloc
+ *
+ * Description:        Allocate a new credential
+ *
+ * Parameters: (void)
+ *
+ * Returns:    !NULL                           Newly allocated credential
+ *             NULL                            Insufficient memory
+ *
+ * Notes:      The newly allocated credential is zero'ed as part of the
+ *             allocation process, with the exception of the reference
+ *             count, which is set to 1 to indicate a single reference
+ *             held by the caller.
+ *
+ *             Since newly allocated credentials have no external pointers
+ *             referencing them, prior to making them visible in an externally
+ *             visible pointer (e.g. by adding them to the credential hash
+ *             cache) is the only legal time in which an existing credential
+ *             can be safely iinitialized or modified directly.
+ *
+ *             After initialization, the caller is expected to call the
+ *             function kauth_cred_add() to add the credential to the hash
+ *             cache, after which time it's frozen and becomes publically
+ *             visible.
+ *
+ *             The release protocol depends on kauth_hash_add() being called
+ *             before kauth_cred_rele() (there is a diagnostic panic which
+ *             will trigger if this protocol is not observed).
+ *
+ * XXX:                This function really ought to be static, rather than being
+ *             exported as KPI, since a failure of kauth_cred_add() can only
+ *             be handled by an explicit free of the credential; such frees
+ *             depend on knowlegdge of the allocation method used, which is
+ *             permitted to change between kernel revisions.
+ *
+ * XXX:                In the insufficient resource case, this code panic's rather
+ *             than returning a NULL pointer; the code that calls this
+ *             function needs to be audited before this can be changed.
  */
 kauth_cred_t
 kauth_cred_alloc(void)
 {
        kauth_cred_t newcred;
        
-       MALLOC(newcred, kauth_cred_t, sizeof(*newcred), M_CRED, M_WAITOK | M_ZERO);
+       MALLOC_ZONE(newcred, kauth_cred_t, sizeof(*newcred), M_CRED, M_WAITOK);
        if (newcred != 0) {
+               bzero(newcred, sizeof(*newcred));
                newcred->cr_ref = 1;
                /* must do this, or cred has same group membership as uid 0 */
                newcred->cr_gmuid = KAUTH_UID_NONE;
@@ -1592,37 +2665,74 @@ kauth_cred_alloc(void)
        kauth_cred_count++;
 #endif
 
+#if CONFIG_MACF
+       mac_cred_label_init(newcred);
+#endif
+
        return(newcred);
 }
 
+
 /*
- * Looks to see if we already have a known credential and if found bumps the
- *     reference count and returns it.  If there are no credentials that match 
- *     the given credential then we allocate a new credential.
+ * kauth_cred_create
+ *
+ * Description:        Look to see if we already have a known credential in the hash
+ *             cache; if one is found, bump the reference count and return
+ *             it.  If there are no credentials that match the given
+ *             credential, then allocate a new credential.
+ *
+ * Parameters: cred                            Template for credential to
+ *                                             be created
+ *
+ * Returns:    (kauth_cred_t)                  The credential that was found
+ *                                             in the hash or created
+ *             NULL                            kauth_cred_add() failed, or
+ *                                             there was not an egid specified
+ *
+ * Notes:      The gmuid is hard-defaulted to the UID specified.  Since we
+ *             maintain this field, we can't expect callers to know how it
+ *             needs to be set.  Callers should be prepared for this field
+ *             to be overwritten.
  *
- * Note that the gmuid is hard-defaulted to the UID specified.  Since we maintain
- * this field, we can't expect callers to know how it needs to be set.  Callers
- * should be prepared for this field to be overwritten.
+ * XXX:                This code will tight-loop if memory for a new credential is
+ *             persistently unavailable; this is perhaps not the wisest way
+ *             to handle this condition, but current callers do not expect
+ *             a failure.
  */
 kauth_cred_t
 kauth_cred_create(kauth_cred_t cred)
 {
        kauth_cred_t    found_cred, new_cred = NULL;
 
-       cred->cr_gmuid = cred->cr_uid;
+       KAUTH_CRED_HASH_LOCK_ASSERT();
+
+       if (cred->cr_flags & CRF_NOMEMBERD)
+               cred->cr_gmuid = KAUTH_UID_NONE;
+       else
+               cred->cr_gmuid = cred->cr_uid;
+
+       /* Caller *must* specify at least the egid in cr_groups[0] */
+       if (cred->cr_ngroups < 1)
+               return(NULL);
        
        for (;;) {
                KAUTH_CRED_HASH_LOCK();
                found_cred = kauth_cred_find(cred);
                if (found_cred != NULL) {
-                       /* found an existing credential so we'll bump reference count and return */
+                       /*
+                        * Found an existing credential so we'll bump
+                        * reference count and return
+                        */
                        kauth_cred_ref(found_cred);
                        KAUTH_CRED_HASH_UNLOCK();
                        return(found_cred);
                }
                KAUTH_CRED_HASH_UNLOCK();
        
-               /* no existing credential found.  create one and add it to our hash table */
+               /*
+                * No existing credential found.  Create one and add it to
+                * our hash table.
+                */
                new_cred = kauth_cred_alloc();
                if (new_cred != NULL) {
                        int             err;
@@ -1634,14 +2744,19 @@ kauth_cred_create(kauth_cred_t cred)
                        new_cred->cr_gmuid = cred->cr_gmuid;
                        new_cred->cr_ngroups = cred->cr_ngroups;        
                        bcopy(&cred->cr_groups[0], &new_cred->cr_groups[0], sizeof(new_cred->cr_groups));
+                       new_cred->cr_flags = cred->cr_flags;
+                       
                        KAUTH_CRED_HASH_LOCK();
                        err = kauth_cred_add(new_cred);
                        KAUTH_CRED_HASH_UNLOCK();
                        
-                       /* retry if kauth_cred_add returns non zero value */
+                       /* Retry if kauth_cred_add returns non zero value */
                        if (err == 0)
                                break;
-                       FREE(new_cred, M_CRED);
+#if CONFIG_MACF
+                       mac_cred_label_destroy(new_cred);
+#endif
+                       FREE_ZONE(new_cred, sizeof(*new_cred), M_CRED);
                        new_cred = NULL;
                }
        }
@@ -1649,146 +2764,217 @@ kauth_cred_create(kauth_cred_t cred)
        return(new_cred);
 }
 
+
 /*
- * Update the given credential using the uid argument.  The given uid is used
- *     set the effective user ID, real user ID, and saved user ID.  We only 
- *     allocate a new credential when the given uid actually results in changes to
- *     the existing credential.
+ * kauth_cred_setresuid
+ *
+ * Description:        Update the given credential using the UID arguments.  The given
+ *             UIDs are used to set the effective UID, real UID, saved UID,
+ *             and GMUID (used for group membership checking).
+ *
+ * Parameters: cred                            The original credential
+ *             ruid                            The new real UID
+ *             euid                            The new effective UID
+ *             svuid                           The new saved UID
+ *             gmuid                           KAUTH_UID_NONE -or- the new
+ *                                             group membership UID
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * Note:       gmuid is different in that a KAUTH_UID_NONE is a valid
+ *             setting, so if you don't want it to change, pass it the
+ *             previous value, explicitly.
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
  */
 kauth_cred_t
-kauth_cred_setuid(kauth_cred_t cred, uid_t uid)
+kauth_cred_setresuid(kauth_cred_t cred, uid_t ruid, uid_t euid, uid_t svuid, uid_t gmuid)
 {
        struct ucred temp_cred;
 
        NULLCRED_CHECK(cred);
 
-       /* don't need to do anything if the effective, real and saved user IDs are
-        * already the same as the user ID passed in
+       /*
+        * We don't need to do anything if the UIDs we are changing are
+        * already the same as the UIDs passed in
         */
-       if (cred->cr_uid == uid && cred->cr_ruid == uid && cred->cr_svuid == uid) {
+       if ((euid == KAUTH_UID_NONE || cred->cr_uid == euid) &&
+           (ruid == KAUTH_UID_NONE || cred->cr_ruid == ruid) &&
+           (svuid == KAUTH_UID_NONE || cred->cr_svuid == svuid) &&
+           (cred->cr_gmuid == gmuid)) {
                /* no change needed */
                return(cred);
        }
 
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
+       /*
+        * Look up in cred hash table to see if we have a matching credential
+        * with the new values; this is done by calling kauth_cred_update().
         */
        bcopy(cred, &temp_cred, sizeof(temp_cred));
-       temp_cred.cr_uid = uid;
-       temp_cred.cr_ruid = uid;
-       temp_cred.cr_svuid = uid;
-       temp_cred.cr_gmuid = uid;
+       if (euid != KAUTH_UID_NONE) {
+               temp_cred.cr_uid = euid;
+       }
+       if (ruid != KAUTH_UID_NONE) {
+               temp_cred.cr_ruid = ruid;
+       }
+       if (svuid != KAUTH_UID_NONE) {
+               temp_cred.cr_svuid = svuid;
+       }
+
+       /*
+        * If we are setting the gmuid to KAUTH_UID_NONE, then we want to
+        * opt out of participation in external group resolution, unless we
+        * unless we explicitly opt back in later.
+        */
+       if ((temp_cred.cr_gmuid = gmuid) == KAUTH_UID_NONE) {
+               temp_cred.cr_flags |= CRF_NOMEMBERD;
+       }
 
        return(kauth_cred_update(cred, &temp_cred, TRUE));
 }
 
+
 /*
- * Update the given credential using the euid argument.  The given uid is used
- *     set the effective user ID.  We only allocate a new credential when the given 
- *     uid actually results in changes to the existing credential.
+ * kauth_cred_setresgid
+ *
+ * Description:        Update the given credential using the GID arguments.  The given
+ *             GIDs are used to set the effective GID, real GID, and saved
+ *             GID.
+ *
+ * Parameters: cred                            The original credential
+ *             rgid                            The new real GID
+ *             egid                            The new effective GID
+ *             svgid                           The new saved GID
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
  */
 kauth_cred_t
-kauth_cred_seteuid(kauth_cred_t cred, uid_t euid)
+kauth_cred_setresgid(kauth_cred_t cred, gid_t rgid, gid_t egid, gid_t svgid)
 {
-       struct ucred temp_cred;
+       struct ucred    temp_cred;
 
        NULLCRED_CHECK(cred);
+       DEBUG_CRED_ENTER("kauth_cred_setresgid %p %d %d %d\n", cred, rgid, egid, svgid);
 
-       /* don't need to do anything if the given effective user ID is already the 
-        *      same as the effective user ID in the credential.
+       /*
+        * We don't need to do anything if the given GID are already the 
+        * same as the GIDs in the credential.
         */
-       if (cred->cr_uid == euid) {
+       if (cred->cr_groups[0] == egid &&
+           cred->cr_rgid == rgid &&
+           cred->cr_svgid == svgid) {
                /* no change needed */
                return(cred);
        }
 
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
+       /*
+        * Look up in cred hash table to see if we have a matching credential
+        * with the new values; this is done by calling kauth_cred_update().
         */
        bcopy(cred, &temp_cred, sizeof(temp_cred));
-       temp_cred.cr_uid = euid;
+       if (egid != KAUTH_GID_NONE) {
+               /* displacing a supplementary group opts us out of memberd */
+               if (kauth_cred_change_egid(&temp_cred, egid)) {
+                       DEBUG_CRED_CHANGE("displaced!\n");
+                       temp_cred.cr_flags |= CRF_NOMEMBERD;
+                       temp_cred.cr_gmuid = KAUTH_UID_NONE;
+               } else {
+                       DEBUG_CRED_CHANGE("not displaced\n");
+               }
+       }
+       if (rgid != KAUTH_GID_NONE) {
+               temp_cred.cr_rgid = rgid;
+       }
+       if (svgid != KAUTH_GID_NONE) {
+               temp_cred.cr_svgid = svgid;
+       }
 
        return(kauth_cred_update(cred, &temp_cred, TRUE));
 }
 
+
 /*
- * Update the given credential using the gid argument.  The given gid is used
- *     set the effective group ID, real group ID, and saved group ID.  We only 
- *     allocate a new credential when the given gid actually results in changes to
- *     the existing credential.
+ * Update the given credential with the given groups.  We only allocate a new 
+ *     credential when the given gid actually results in changes to the existing 
+ *     credential.
+ *     The gmuid argument supplies a new uid (or KAUTH_UID_NONE to opt out)
+ *     which will be used for group membership checking.
+ */
+/*
+ * kauth_cred_setgroups
+ *
+ * Description:        Update the given credential using the provide supplementary
+ *             group list and group membership UID
+ *
+ * Parameters: cred                            The original credential
+ *             groups                          Pointer to gid_t array which
+ *                                             contains the new group list
+ *             groupcount                      The cound of valid groups which
+ *                                             are contained in 'groups'
+ *             gmuid                           KAUTH_UID_NONE -or- the new
+ *                                             group membership UID
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * Note:       gmuid is different in that a KAUTH_UID_NONE is a valid
+ *             setting, so if you don't want it to change, pass it the
+ *             previous value, explicitly.
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
+ *
+ * XXX:                Changes are determined in ordinal order - if the caller pasess
+ *             in the same groups list that is already present in the
+ *             credential, but the members are in a different order, even if
+ *             the EGID is not modified (i.e. cr_groups[0] is the same), it
+ *             is considered a modification to the credential, and a new
+ *             credential is created.
+ *
+ *             This should perhaps be better optimized, but it is considered
+ *             to be the caller's problem.
  */
 kauth_cred_t
-kauth_cred_setgid(kauth_cred_t cred, gid_t gid)
+kauth_cred_setgroups(kauth_cred_t cred, gid_t *groups, int groupcount, uid_t gmuid)
 {
-       struct ucred    temp_cred;
+       int             i;
+       struct ucred temp_cred;
 
        NULLCRED_CHECK(cred);
 
-       /* don't need to do anything if the given group ID is already the 
-        *      same as the group ID in the credential.
-        */
-       if (cred->cr_groups[0] == gid && cred->cr_rgid == gid && cred->cr_svgid == gid) {
-               /* no change needed */
-               return(cred);
-       }
-
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
-        */
-       bcopy(cred, &temp_cred, sizeof(temp_cred));
-       temp_cred.cr_groups[0] = gid;
-       temp_cred.cr_rgid = gid;
-       temp_cred.cr_svgid = gid;
-
-       return(kauth_cred_update(cred, &temp_cred, TRUE));
-}
-
-
-/*
- * Update the given credential using the egid argument.  The given gid is used
- *     set the effective user ID.  We only allocate a new credential when the given 
- *     gid actually results in changes to the existing credential.
- */
-kauth_cred_t
-kauth_cred_setegid(kauth_cred_t cred, gid_t egid)
-{
-       struct ucred temp_cred;
-
-       NULLCRED_CHECK(cred);
-
-       /* don't need to do anything if the given group ID is already the 
-        *      same as the group Id in the credential.
-        */
-       if (cred->cr_groups[0] == egid) {
-               /* no change needed */
-               return(cred);
-       }
-
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
-        */
-       bcopy(cred, &temp_cred, sizeof(temp_cred));
-       temp_cred.cr_groups[0] = egid;
-
-       return(kauth_cred_update(cred, &temp_cred, TRUE));
-}
-
-/*
- * Update the given credential with the given groups.  We only allocate a new 
- *     credential when the given gid actually results in changes to the existing 
- *     credential.
- *     The gmuid argument supplies a new uid (or KAUTH_UID_NONE to opt out)
- *     which will be used for group membership checking.
- */
-kauth_cred_t
-kauth_cred_setgroups(kauth_cred_t cred, gid_t *groups, int groupcount, uid_t gmuid)
-{
-       int             i;
-       struct ucred temp_cred;
-
-       NULLCRED_CHECK(cred);
-
-       /* don't need to do anything if the given list of groups does not change.
+       /*
+        * We don't need to do anything if the given list of groups does not
+        * change.
         */
        if ((cred->cr_gmuid == gmuid) && (cred->cr_ngroups == groupcount)) {
                for (i = 0; i < groupcount; i++) {
@@ -1801,24 +2987,60 @@ kauth_cred_setgroups(kauth_cred_t cred, gid_t *groups, int groupcount, uid_t gmu
                }
        }
 
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
+       /*
+        * Look up in cred hash table to see if we have a matching credential
+        * with new values.  If we are setting or clearing the gmuid, then
+        * update the cr_flags, since clearing it is sticky.  This permits an
+        * opt-out of memberd processing using setgroups(), and an opt-in
+        * using initgroups().  This is required for POSIX conformance.
         */
        bcopy(cred, &temp_cred, sizeof(temp_cred));
        temp_cred.cr_ngroups = groupcount;
        bcopy(groups, temp_cred.cr_groups, sizeof(temp_cred.cr_groups));
        temp_cred.cr_gmuid = gmuid;
+       if (gmuid == KAUTH_UID_NONE)
+               temp_cred.cr_flags |= CRF_NOMEMBERD;
+       else
+               temp_cred.cr_flags &= ~CRF_NOMEMBERD;
 
        return(kauth_cred_update(cred, &temp_cred, TRUE));
 }
 
+
 /*
- * Update the given credential using the uid and gid arguments.  The given uid 
- *     is used set the effective user ID, real user ID, and saved user ID.  
- *     The given gid is used set the effective group ID, real group ID, and saved 
- *     group ID.
- *     We only allocate a new credential when the given uid and gid actually results 
- *     in changes to the existing credential.
+ * kauth_cred_setuidgid
+ *
+ * Description:        Update the given credential using the UID and GID arguments.
+ *             The given UID is used to set the effective UID, real UID, and
+ *             saved UID.  The given GID is used to set the effective GID,
+ *             real GID, and saved GID.
+ *
+ * Parameters: cred                            The original credential
+ *             uid                             The new UID to use
+ *             gid                             The new GID to use
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * Notes:      We set the gmuid to uid if the credential we are inheriting
+ *             from has not opted out of memberd participation; otherwise
+ *             we set it to KAUTH_UID_NONE
+ *
+ *             This code is only ever called from the per-thread credential
+ *             code path in the "set per thread credential" case; and in
+ *             posix_spawn() in the case that the POSIX_SPAWN_RESETIDS
+ *             flag is set.
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
  */
 kauth_cred_t
 kauth_cred_setuidgid(kauth_cred_t cred, uid_t uid, gid_t gid)
@@ -1827,8 +3049,9 @@ kauth_cred_setuidgid(kauth_cred_t cred, uid_t uid, gid_t gid)
 
        NULLCRED_CHECK(cred);
 
-       /* don't need to do anything if the effective, real and saved user IDs are
-        * already the same as the user ID passed in
+       /*
+        * We don't need to do anything if the effective, real and saved
+        * user IDs are already the same as the user ID passed into us.
         */
        if (cred->cr_uid == uid && cred->cr_ruid == uid && cred->cr_svuid == uid &&
                cred->cr_groups[0] == gid && cred->cr_rgid == gid && cred->cr_svgid == gid) {
@@ -1836,28 +3059,61 @@ kauth_cred_setuidgid(kauth_cred_t cred, uid_t uid, gid_t gid)
                return(cred);
        }
 
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
+       /*
+        * Look up in cred hash table to see if we have a matching credential
+        * with the new values.
         */
        bzero(&temp_cred, sizeof(temp_cred));
        temp_cred.cr_uid = uid;
        temp_cred.cr_ruid = uid;
        temp_cred.cr_svuid = uid;
-       temp_cred.cr_gmuid = uid;
+       /* inherit the opt-out of memberd */
+       if (cred->cr_flags & CRF_NOMEMBERD) {
+               temp_cred.cr_gmuid = KAUTH_UID_NONE;
+               temp_cred.cr_flags |= CRF_NOMEMBERD;
+       } else {
+               temp_cred.cr_gmuid = uid;
+               temp_cred.cr_flags &= ~CRF_NOMEMBERD;
+       }
        temp_cred.cr_ngroups = 1;
-       temp_cred.cr_groups[0] = gid;
+       /* displacing a supplementary group opts us out of memberd */
+       if (kauth_cred_change_egid(&temp_cred, gid)) {
+               temp_cred.cr_gmuid = KAUTH_UID_NONE;
+               temp_cred.cr_flags |= CRF_NOMEMBERD;
+       }
        temp_cred.cr_rgid = gid;
        temp_cred.cr_svgid = gid;
+#if CONFIG_MACF
+       temp_cred.cr_label = cred->cr_label;
+#endif
 
        return(kauth_cred_update(cred, &temp_cred, TRUE));
 }
 
+
 /*
- * Update the given credential using the uid and gid arguments.  The given uid 
- *     is used to set the saved user ID.  The given gid is used to set the 
- *     saved group ID.
- *     We only allocate a new credential when the given uid and gid actually results 
- *     in changes to the existing credential.
+ * kauth_cred_setsvuidgid
+ *
+ * Description:        Function used by execve to set the saved uid and gid values
+ *             for suid/sgid programs
+ *
+ * Parameters: cred                            The credential to update
+ *             uid                             The saved uid to set
+ *             gid                             The saved gid to set
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
  */
 kauth_cred_t
 kauth_cred_setsvuidgid(kauth_cred_t cred, uid_t uid, gid_t gid)
@@ -1865,14 +3121,18 @@ kauth_cred_setsvuidgid(kauth_cred_t cred, uid_t uid, gid_t gid)
        struct ucred temp_cred;
 
        NULLCRED_CHECK(cred);
+       DEBUG_CRED_ENTER("kauth_cred_setsvuidgid: %p u%d->%d g%d->%d\n", cred, cred->cr_svuid, uid, cred->cr_svgid, gid);
 
-       /* don't need to do anything if the effective, real and saved user IDs are
-        * already the same as the user ID passed in
+       /*
+        * We don't need to do anything if the effective, real and saved
+        * uids are already the same as the uid provided.  This check is
+        * likely insufficient.
         */
        if (cred->cr_svuid == uid && cred->cr_svgid == gid) {
                /* no change needed */
                return(cred);
        }
+       DEBUG_CRED_CHANGE("kauth_cred_setsvuidgid: cred change\n");
 
        /* look up in cred hash table to see if we have a matching credential
         * with new values.
@@ -1884,10 +3144,28 @@ kauth_cred_setsvuidgid(kauth_cred_t cred, uid_t uid, gid_t gid)
        return(kauth_cred_update(cred, &temp_cred, TRUE));
 }
 
+
 /*
- * Update the given credential using the given auditinfo_t.
- *     We only allocate a new credential when the given auditinfo_t actually results 
- *     in changes to the existing credential.
+ * kauth_cred_setauditinfo
+ * 
+ * Description:        Update the given credential using the given auditinfo_t.
+ *
+ * Parameters: cred                            The original credential
+ *             auditinfo_p                     Pointer to ne audit information
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
  */
 kauth_cred_t
 kauth_cred_setauditinfo(kauth_cred_t cred, auditinfo_t *auditinfo_p)
@@ -1896,25 +3174,314 @@ kauth_cred_setauditinfo(kauth_cred_t cred, auditinfo_t *auditinfo_p)
 
        NULLCRED_CHECK(cred);
 
-       /* don't need to do anything if the audit info is already the same as the 
-        * audit info in the credential passed in
+       /*
+        * We don't need to do anything if the audit info is already the
+        * same as the audit info in the credential provided.
         */
        if (bcmp(&cred->cr_au, auditinfo_p, sizeof(cred->cr_au)) == 0) {
                /* no change needed */
                return(cred);
        }
 
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
-        */
        bcopy(cred, &temp_cred, sizeof(temp_cred));
        bcopy(auditinfo_p, &temp_cred.cr_au, sizeof(temp_cred.cr_au));
 
        return(kauth_cred_update(cred, &temp_cred, FALSE));
 }
 
+#if CONFIG_MACF
 /*
- * Add a reference to the passed credential.
+ * kauth_cred_label_update
+ * 
+ * Description:        Update the MAC label associated with a credential
+ *
+ * Parameters: cred                            The original credential
+ *             label                           The MAC label to set
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
+ */
+kauth_cred_t
+kauth_cred_label_update(kauth_cred_t cred, struct label *label)
+{
+       kauth_cred_t newcred;
+       struct ucred temp_cred;
+
+       bcopy(cred, &temp_cred, sizeof(temp_cred));
+
+       mac_cred_label_init(&temp_cred);
+       mac_cred_label_associate(cred, &temp_cred);
+       mac_cred_label_update(&temp_cred, label);
+
+       newcred = kauth_cred_update(cred, &temp_cred, TRUE);
+       mac_cred_label_destroy(&temp_cred);
+       return (newcred);
+}
+
+/*
+ * kauth_cred_label_update_execve
+ * 
+ * Description:        Update the MAC label associated with a credential as
+ *             part of exec
+ *
+ * Parameters: cred                            The original credential
+ *             vp                              The exec vnode
+ *             scriptl                         The script MAC label
+ *             execl                           The executable MAC label
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * IMPORTANT:  This function is implemented via kauth_cred_update(), which,
+ *             if it returns a credential other than the one it is passed,
+ *             will have dropped the reference on the passed credential.  All
+ *             callers should be aware of this, and treat this function as an
+ *             unref + ref, potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
+ */
+static
+kauth_cred_t
+kauth_cred_label_update_execve(kauth_cred_t cred, vfs_context_t ctx,
+       struct vnode *vp, struct label *scriptl, struct label *execl)
+{
+       kauth_cred_t newcred;
+       struct ucred temp_cred;
+
+       bcopy(cred, &temp_cred, sizeof(temp_cred));
+
+       mac_cred_label_init(&temp_cred);
+       mac_cred_label_associate(cred, &temp_cred);
+       mac_cred_label_update_execve(ctx, &temp_cred, 
+                                    vp, scriptl, execl);
+
+       newcred = kauth_cred_update(cred, &temp_cred, TRUE);
+       mac_cred_label_destroy(&temp_cred);
+       return (newcred);
+}
+
+/*
+ *  kauth_proc_label_update
+ *
+ * Description:  Update the label inside the credential associated with the process.
+ *
+ * Parameters: p                       The process to modify
+ *                             label           The label to place in the process credential
+ *
+ * Notes:              The credential associated with the process may change as a result
+ *                             of this call.  The caller should not assume the process reference to
+ *                             the old credential still exists.
+ */
+int kauth_proc_label_update(struct proc *p, struct label *label)
+{
+       kauth_cred_t my_cred, my_new_cred;
+
+       my_cred = kauth_cred_proc_ref(p);
+
+       DEBUG_CRED_ENTER("kauth_proc_label_update: %p\n", my_cred);
+
+       /* get current credential and take a reference while we muck with it */
+       for (;;) {
+
+               /* 
+                * Set the credential with new info.  If there is no change,
+                * we get back the same credential we passed in; if there is
+                * a change, we drop the reference on the credential we
+                * passed in.  The subsequent compare is safe, because it is
+                * a pointer compare rather than a contents compare.
+                */
+               my_new_cred = kauth_cred_label_update(my_cred, label);
+               if (my_cred != my_new_cred) {
+
+                       DEBUG_CRED_CHANGE("kauth_proc_setlabel_unlocked CH(%d): %p/0x%08x -> %p/0x%08x\n", p->p_pid, my_cred, my_cred->cr_flags, my_new_cred, my_new_cred->cr_flags);
+
+                       proc_lock(p);
+                       /*
+                        * We need to protect for a race where another thread
+                        * also changed the credential after we took our
+                        * reference.  If p_ucred has changed then we should
+                        * restart this again with the new cred.
+                        */
+                       if (p->p_ucred != my_cred) {
+                               proc_unlock(p);
+                               kauth_cred_unref(&my_new_cred);
+                               my_cred = kauth_cred_proc_ref(p);
+                               /* try again */
+                               continue;
+                       }
+                       p->p_ucred = my_new_cred;
+                       mac_proc_set_enforce(p, MAC_ALL_ENFORCE);
+                       proc_unlock(p);
+               }
+               break;
+       }
+       /* Drop old proc reference or our extra reference */
+       kauth_cred_unref(&my_cred);
+       
+       return (0);
+}
+
+/*
+ *  kauth_proc_label_update_execve
+ *
+ * Description: Update the label inside the credential associated with the
+ *             process as part of a transitioning execve.  The label will
+ *             be updated by the policies as part of this processing, not
+ *             provided up front.
+ *
+ * Parameters: p                       The process to modify
+ *             ctx                     The context of the exec
+ *             vp                      The vnode being exec'ed
+ *             scriptl                 The script MAC label
+ *             execl                   The executable MAC label
+ *
+ * Notes:      The credential associated with the process WILL change as a
+ *             result of this call.  The caller should not assume the process
+ *             reference to the old credential still exists.
+ */
+int kauth_proc_label_update_execve(struct proc *p, vfs_context_t ctx,
+       struct vnode *vp, struct label *scriptl, struct label *execl)
+{
+       kauth_cred_t my_cred, my_new_cred;
+
+       my_cred = kauth_cred_proc_ref(p);
+
+       DEBUG_CRED_ENTER("kauth_proc_label_update_execve: %p\n", my_cred);
+
+       /* get current credential and take a reference while we muck with it */
+       for (;;) {
+
+               /* 
+                * Set the credential with new info.  If there is no change,
+                * we get back the same credential we passed in; if there is
+                * a change, we drop the reference on the credential we
+                * passed in.  The subsequent compare is safe, because it is
+                * a pointer compare rather than a contents compare.
+                */
+               my_new_cred = kauth_cred_label_update_execve(my_cred, ctx, vp, scriptl, execl);
+               if (my_cred != my_new_cred) {
+
+                       DEBUG_CRED_CHANGE("kauth_proc_label_update_execve_unlocked CH(%d): %p/0x%08x -> %p/0x%08x\n", p->p_pid, my_cred, my_cred->cr_flags, my_new_cred, my_new_cred->cr_flags);
+
+                       proc_lock(p);
+                       /*
+                        * We need to protect for a race where another thread
+                        * also changed the credential after we took our
+                        * reference.  If p_ucred has changed then we should
+                        * restart this again with the new cred.
+                        */
+                       if (p->p_ucred != my_cred) {
+                               proc_unlock(p);
+                               kauth_cred_unref(&my_new_cred);
+                               my_cred = kauth_cred_proc_ref(p);
+                               /* try again */
+                               continue;
+                       }
+                       p->p_ucred = my_new_cred;
+                       mac_proc_set_enforce(p, MAC_ALL_ENFORCE);
+                       proc_unlock(p);
+               }
+               break;
+       }
+       /* Drop old proc reference or our extra reference */
+       kauth_cred_unref(&my_cred);
+       
+       return (0);
+}
+
+#if 1
+/*
+ * for temporary binary compatibility
+ */
+kauth_cred_t   kauth_cred_setlabel(kauth_cred_t cred, struct label *label);
+kauth_cred_t
+kauth_cred_setlabel(kauth_cred_t cred, struct label *label)
+{
+       return kauth_cred_label_update(cred, label);
+}
+
+int kauth_proc_setlabel(struct proc *p, struct label *label);
+int
+kauth_proc_setlabel(struct proc *p, struct label *label)
+{
+       return kauth_proc_label_update(p, label);
+}
+#endif
+
+#else
+
+/* this is a temp hack to cover us when MACF is not built in a kernel configuration. 
+ * Since we cannot build our export lists based on the kernel configuration we need
+ * to define a stub. 
+ */
+kauth_cred_t
+kauth_cred_label_update(__unused kauth_cred_t cred, __unused void *label)
+{
+       return(NULL);
+}
+
+int
+kauth_proc_label_update(__unused struct proc *p, __unused void *label)
+{
+       return (0);
+}
+
+#if 1
+/*
+ * for temporary binary compatibility
+ */
+kauth_cred_t   kauth_cred_setlabel(kauth_cred_t cred, void *label);
+kauth_cred_t
+kauth_cred_setlabel(__unused kauth_cred_t cred, __unused void *label)
+{
+       return NULL;
+}
+
+int kauth_proc_setlabel(struct proc *p, void *label);
+int
+kauth_proc_setlabel(__unused struct proc *p, __unused void *label)
+{
+       return (0);
+}
+#endif
+#endif
+
+/*
+ * kauth_cred_ref
+ *
+ * Description:        Add a reference to the passed credential
+ *
+ * Parameters: cred                            The credential to reference
+ *
+ * Returns:    (void)
+ *
+ * Notes:      This function adds a reference to the provided credential;
+ *             the existing reference on the credential is assumed to be
+ *             held stable over this operation by taking the appropriate
+ *             lock to protect the pointer from which it is being referenced,
+ *             if necessary (e.g. the proc lock is held over the call if the
+ *             credential being referenced is from p_ucred, the vnode lock
+ *             if from the per vnode name cache cred cache, and so on).
+ *
+ *             This is safe from the kauth_cred_unref() path, since an atomic
+ *             add is used, and the unref path specifically checks to see that
+ *             the value has not been changed to add a reference between the
+ *             time the credential is unreferenced by another pointer and the
+ *             time it is unreferenced from the cred hash cache.
  */
 void
 kauth_cred_ref(kauth_cred_t cred)
@@ -1923,31 +3490,49 @@ kauth_cred_ref(kauth_cred_t cred)
        
        NULLCRED_CHECK(cred);
 
-       old_value = OSAddAtomic(1, &cred->cr_ref);
+       // XXX SInt32 not safe for an LP64 kernel
+       old_value = OSAddAtomic(1, (SInt32 *)&cred->cr_ref);
 
        if (old_value < 1)
                panic("kauth_cred_ref: trying to take a reference on a cred with no references");
+
+#if 0 // use this to watch a specific credential
+       if ( is_target_cred( cred ) != 0 ) {
+               get_backtrace( );
+       }
+#endif
                
        return;
 }
 
-/*
- * Drop a reference from the passed credential, potentially destroying it.
- *
- * Note:       Assumes credential hash is NOT locked
- */
-void
-kauth_cred_unref(kauth_cred_t *credp)
-{
-       KAUTH_CRED_HASH_LOCK();
-       kauth_cred_unref_hashlocked(credp);
-       KAUTH_CRED_HASH_UNLOCK();
-}
 
 /*
- * Drop a reference from the passed credential, potentially destroying it.
+ * kauth_cred_unref_hashlocked
+ *
+ * Description:        release a credential reference; when the last reference is
+ *             released, the credential will be freed.
+ *
+ * Parameters: credp                           Pointer to address containing
+ *                                             credential to be freed
+ *
+ * Returns:    (void)
  *
- * Note:       Assumes credential hash IS locked
+ * Implicit returns:
+ *             *credp                          Set to NOCRED
+ *
+ * Notes:      This function assumes the credential hash lock is held.
+ *
+ *             This function is internal use only, since the hash lock is
+ *             scoped to this compilation unit.
+ *
+ *             This function destroys the contents of the pointer passed by
+ *             the caller to prevent the caller accidently attempting to
+ *             release a given reference twice in error.
+ *
+ *             The last reference is considered to be released when a release
+ *             of a credential of a reference count of 2 occurs; this is an
+ *             intended effect, to take into accout the reference held by
+ *             the credential hash, which is released at the same time.
  */
 static void
 kauth_cred_unref_hashlocked(kauth_cred_t *credp)
@@ -1956,36 +3541,130 @@ kauth_cred_unref_hashlocked(kauth_cred_t *credp)
 
        KAUTH_CRED_HASH_LOCK_ASSERT();
        NULLCRED_CHECK(*credp);
-       old_value = OSAddAtomic(-1, &(*credp)->cr_ref);
+
+       // XXX SInt32 not safe for an LP64 kernel
+       old_value = OSAddAtomic(-1, (SInt32 *)&(*credp)->cr_ref);
 
 #if DIAGNOSTIC
        if (old_value == 0)
-               panic("%s:0x%08x kauth_cred_rele: dropping a reference on a cred with no references", current_proc()->p_comm, *credp);
+               panic("%s:0x%08x kauth_cred_unref_hashlocked: dropping a reference on a cred with no references", current_proc()->p_comm, *credp);
        if (old_value == 1)
-               panic("%s:0x%08x kauth_cred_rele: dropping a reference on a cred with no hash entry", current_proc()->p_comm, *credp);
+               panic("%s:0x%08x kauth_cred_unref_hashlocked: dropping a reference on a cred with no hash entry", current_proc()->p_comm, *credp);
+#endif
+
+#if 0 // use this to watch a specific credential
+       if ( is_target_cred( *credp ) != 0 ) {
+               get_backtrace( );
+       }
 #endif
 
+       /*
+        * If the old_value is 2, then we have just released the last external
+        * reference to this credential
+        */
        if (old_value < 3) {
-               /* the last reference is our credential hash table */
+               /* The last absolute reference is our credential hash table */
                kauth_cred_remove(*credp);
        }
        *credp = NOCRED;
 }
 
+
+/*
+ * kauth_cred_unref
+ *
+ * Description:        Release a credential reference while holding the credential
+ *             hash lock; when the last reference is released, the credential
+ *             will be freed.
+ *
+ * Parameters: credp                           Pointer to address containing
+ *                                             credential to be freed
+ *
+ * Returns:    (void)
+ *
+ * Implicit returns:
+ *             *credp                          Set to NOCRED
+ *
+ * Notes:      See kauth_cred_unref_hashlocked() for more information.
+ *
+ */
+void
+kauth_cred_unref(kauth_cred_t *credp)
+{
+       KAUTH_CRED_HASH_LOCK();
+       kauth_cred_unref_hashlocked(credp);
+       KAUTH_CRED_HASH_UNLOCK();
+}
+
+
+/*
+ * kauth_cred_rele
+ *
+ * Description:        release a credential reference; when the last reference is
+ *             released, the credential will be freed
+ *
+ * Parameters: cred                            Credential to release
+ *
+ * Returns:    (void)
+ *
+ * DEPRECATED: This interface is obsolete due to a failure to clear out the
+ *             clear the pointer in the caller to avoid multiple releases of
+ *             the same credential.  The currently recommended interface is
+ *             kauth_cred_unref().
+ */
 void
 kauth_cred_rele(kauth_cred_t cred)
 {
        kauth_cred_unref(&cred);
 }
 
+
 /*
- * Duplicate a credential.
- *     NOTE - caller should call kauth_cred_add after any credential changes are made.
+ * kauth_cred_dup
+ *
+ * Description:        Duplicate a credential via alloc and copy; the new credential
+ *             has only it's own
+ *
+ * Parameters: cred                            The credential to duplicate
+ *
+ * Returns:    (kauth_cred_t)                  The duplicate credential
+ *
+ * Notes:      The typical value to calling this routine is if you are going
+ *             to modify an existing credential, and expect to need a new one
+ *             from the hash cache.
+ *
+ *             This should probably not be used in the majority of cases;
+ *             if you are using it instead of kauth_cred_create(), you are
+ *             likely making a mistake.
+ *
+ *             The newly allocated credential is copied as part of the
+ *             allocation process, with the exception of the reference
+ *             count, which is set to 1 to indicate a single reference
+ *             held by the caller.
+ *
+ *             Since newly allocated credentials have no external pointers
+ *             referencing them, prior to making them visible in an externally
+ *             visible pointer (e.g. by adding them to the credential hash
+ *             cache) is the only legal time in which an existing credential
+ *             can be safely iinitialized or modified directly.
+ *
+ *             After initialization, the caller is expected to call the
+ *             function kauth_cred_add() to add the credential to the hash
+ *             cache, after which time it's frozen and becomes publically
+ *             visible.
+ *
+ *             The release protocol depends on kauth_hash_add() being called
+ *             before kauth_cred_rele() (there is a diagnostic panic which
+ *             will trigger if this protocol is not observed).
+ *
  */
 kauth_cred_t
 kauth_cred_dup(kauth_cred_t cred)
 {
        kauth_cred_t newcred;
+#if CONFIG_MACF
+       struct label *temp_label;
+#endif
        
 #if CRED_DIAGNOSTIC
        if (cred == NOCRED || cred == FSCRED)
@@ -1993,16 +3672,35 @@ kauth_cred_dup(kauth_cred_t cred)
 #endif
        newcred = kauth_cred_alloc();
        if (newcred != NULL) {
+#if CONFIG_MACF
+               temp_label = newcred->cr_label;
+#endif
                bcopy(cred, newcred, sizeof(*newcred));
+#if CONFIG_MACF
+               newcred->cr_label = temp_label;
+               mac_cred_label_associate(cred, newcred);
+#endif
                newcred->cr_ref = 1;
        }
        return(newcred);
 }
 
 /*
- * Returns a credential based on the passed credential but which
- * reflects the real rather than effective UID and GID.
- * NOTE - we do NOT decrement cred reference count on passed in credential
+ * kauth_cred_copy_real
+ *
+ * Description:        Returns a credential based on the passed credential but which
+ *             reflects the real rather than effective UID and GID.
+ *
+ * Parameters: cred                            The credential from which to
+ *                                             derive the new credential
+ *
+ * Returns:    (kauth_cred_t)                  The copied credential
+ *
+ * IMPORTANT:  This function DOES NOT utilize kauth_cred_update(); as a
+ *             result, the caller is responsible for dropping BOTH the
+ *             additional reference on the passed cred (if any), and the
+ *             credential returned by this function.  The drop should be
+ *             via the satnadr kauth_cred_unref() KPI.
  */
 kauth_cred_t
 kauth_cred_copy_real(kauth_cred_t cred)
@@ -2017,14 +3715,19 @@ kauth_cred_copy_real(kauth_cred_t cred)
                return(cred);
        }
 
-       /* look up in cred hash table to see if we have a matching credential
-        * with new values.
+       /*
+        * Look up in cred hash table to see if we have a matching credential
+        * with the new values.
         */
        bcopy(cred, &temp_cred, sizeof(temp_cred));
        temp_cred.cr_uid = cred->cr_ruid;
-       temp_cred.cr_groups[0] = cred->cr_rgid;
+       /* displacing a supplementary group opts us out of memberd */
+       if (kauth_cred_change_egid(&temp_cred, cred->cr_rgid)) {
+               temp_cred.cr_flags |= CRF_NOMEMBERD;
+               temp_cred.cr_gmuid = KAUTH_UID_NONE;
+       }
        /*
-        * if the cred is not opted out, make sure we are using the r/euid
+        * If the cred is not opted out, make sure we are using the r/euid
         * for group checks
         */
        if (temp_cred.cr_gmuid != KAUTH_UID_NONE)
@@ -2042,47 +3745,74 @@ kauth_cred_copy_real(kauth_cred_t cred)
                }
                if (found_cred != NULL) {
                        /*
-                        * found a match so we bump reference count on new one.
-                        * we leave the old one alone.
+                        * Found a match so we bump reference count on new
+                        * one.  We leave the old one alone.
                         */
                        kauth_cred_ref(found_cred);
                        KAUTH_CRED_HASH_UNLOCK();
                        return(found_cred);
                }
        
-               /* must allocate a new credential, copy in old credential data and update
-                * with real user and group IDs.
+               /*
+                * Must allocate a new credential, copy in old credential
+                * data and update the real user and group IDs.
                 */
                newcred = kauth_cred_dup(&temp_cred);
                err = kauth_cred_add(newcred);
                KAUTH_CRED_HASH_UNLOCK();
 
-               /* retry if kauth_cred_add returns non zero value */
+               /* Retry if kauth_cred_add() fails */
                if (err == 0)
                        break;
-               FREE(newcred, M_CRED);
+#if CONFIG_MACF
+               mac_cred_label_destroy(newcred);
+#endif
+               FREE_ZONE(newcred, sizeof(*newcred), M_CRED);
                newcred = NULL;
        }
        
        return(newcred);
 }
-       
+
+
 /*
- * Common code to update a credential.  model_cred is a temporary, non
- * reference counted credential used only for comparison and modeling
- * purposes.  old_cred is a live reference counted credential that we
- * intend to update using model_cred as our model.
+ * kauth_cred_update
  *
- * IMPORTANT:  If the old_cred ends up updated by this process, we will, as
- *             a side effect, drop the reference we held on it going in.
+ * Description:        Common code to update a credential
+ *
+ * Parameters: old_cred                        Reference counted credential
+ *                                             to update
+ *             model_cred                      Non-reference counted model
+ *                                             credential to apply to the
+ *                                             credential to be updated
+ *             retain_auditinfo                Flag as to whether or not the
+ *                                             audit information should be
+ *                                             copied from the old_cred into
+ *                                             the model_cred
+ *
+ * Returns:    (kauth_cred_t)                  The updated credential
+ *
+ * IMPORTANT:  This function will potentially return a credential other than
+ *             the one it is passed, and if so, it will have dropped the
+ *             reference on the passed credential.  All callers should be
+ *             aware of this, and treat this function as an unref + ref,
+ *             potentially on different credentials.
+ *
+ *             Because of this, the caller is expected to take its own
+ *             reference on the credential passed as the first parameter,
+ *             and be prepared to release the reference on the credential
+ *             that is returned to them, if it is not intended to be a
+ *             persistent reference.
  */
 static kauth_cred_t
-kauth_cred_update(kauth_cred_t old_cred, kauth_cred_t model_cred, boolean_t retain_auditinfo)
+kauth_cred_update(kauth_cred_t old_cred, kauth_cred_t model_cred,
+       boolean_t retain_auditinfo)
 {      
        kauth_cred_t found_cred, new_cred = NULL;
        
-       /* make sure we carry the auditinfo forward to the new credential unless
-        * we are actually updating the auditinfo.
+       /*
+        * Make sure we carry the auditinfo forward to the new credential
+        * unless we are actually updating the auditinfo.
         */
        if (retain_auditinfo)
                bcopy(&old_cred->cr_au, &model_cred->cr_au, sizeof(model_cred->cr_au));
@@ -2098,8 +3828,9 @@ kauth_cred_update(kauth_cred_t old_cred, kauth_cred_t model_cred, boolean_t reta
                        return(old_cred); 
                }
                if (found_cred != NULL) {
+                       DEBUG_CRED_CHANGE("kauth_cred_update(cache hit): %p -> %p\n", old_cred, found_cred);
                        /*
-                        * found a match so we bump reference count on new
+                        * Found a match so we bump reference count on new
                         * one and decrement reference count on the old one.
                         */
                        kauth_cred_ref(found_cred);
@@ -2108,7 +3839,8 @@ kauth_cred_update(kauth_cred_t old_cred, kauth_cred_t model_cred, boolean_t reta
                        return(found_cred);
                }
        
-               /* must allocate a new credential using the model.  also
+               /*
+                * Must allocate a new credential using the model.  also
                 * adds the new credential to the credential hash table.
                 */
                new_cred = kauth_cred_dup(model_cred);
@@ -2118,18 +3850,36 @@ kauth_cred_update(kauth_cred_t old_cred, kauth_cred_t model_cred, boolean_t reta
                /* retry if kauth_cred_add returns non zero value */
                if (err == 0)
                        break;
-               FREE(new_cred, M_CRED);
+#if CONFIG_MACF
+               mac_cred_label_destroy(new_cred);
+#endif
+               FREE_ZONE(new_cred, sizeof(*new_cred), M_CRED);
                new_cred = NULL;
        }
 
+       DEBUG_CRED_CHANGE("kauth_cred_update(cache miss): %p -> %p\n", old_cred, new_cred);
        kauth_cred_unref(&old_cred);
        return(new_cred);
 }
 
-/* 
- *     Add the given credential to our credential hash table and take an additional
- *     reference to account for our use of the credential in the hash table.
- *     NOTE - expects caller to hold KAUTH_CRED_HASH_LOCK!
+
+/*
+ * kauth_cred_add
+ *
+ * Description:        Add the given credential to our credential hash table and
+ *             take an additional reference to account for our use of the
+ *             credential in the hash table
+ *
+ * Parameters: new_cred                        Credential to insert into cred
+ *                                             hash cache
+ *
+ * Returns:    0                               Success
+ *             -1                              Hash insertion failed: caller
+ *                                             should retry
+ *
+ * Locks:      Caller is expected to hold KAUTH_CRED_HASH_LOCK
+ *
+ * Notes:      The 'new_cred' MUST NOT already be in the cred hash cache
  */
 static int
 kauth_cred_add(kauth_cred_t new_cred)
@@ -2161,8 +3911,21 @@ kauth_cred_add(kauth_cred_t new_cred)
 
 
 /* 
- *     Remove the given credential from our credential hash table.
- *     NOTE - expects caller to hold KAUTH_CRED_HASH_LOCK!
+ * kauth_cred_remove
+ *
+ * Description:        Remove the given credential from our credential hash table
+ *
+ * Parameters: cred                            Credential to remove from cred
+ *                                             hash cache
+ *
+ * Returns:    (void)
+ *
+ * Locks:      Caller is expected to hold KAUTH_CRED_HASH_LOCK
+ *
+ * Notes:      The check for the reference increment after entry is generally
+ *             agree to be safe, since we use atomic operations, and the
+ *             following code occurs with the hash lock held; in theory, this
+ *             protects us from the 2->1 reference that gets us here.
  */
 static void
 kauth_cred_remove(kauth_cred_t cred)
@@ -2170,24 +3933,25 @@ kauth_cred_remove(kauth_cred_t cred)
        u_long                  hash_key;
        kauth_cred_t    found_cred;
 
-       KAUTH_CRED_HASH_LOCK_ASSERT();
-
        hash_key = kauth_cred_get_hashkey(cred);
        hash_key %= kauth_cred_table_size;
 
-       /* avoid race */
+       /* Avoid race */
        if (cred->cr_ref < 1)
                panic("cred reference underflow");
-       if (cred->cr_ref > 1) {
+       if (cred->cr_ref > 1)
                return;         /* someone else got a ref */
-       }
-
-       /* find cred in the credential hash table */
+               
+       /* Find cred in the credential hash table */
        TAILQ_FOREACH(found_cred, &kauth_cred_table_anchor[hash_key], cr_link) {
                if (found_cred == cred) {
                        /* found a match, remove it from the hash table */
                        TAILQ_REMOVE(&kauth_cred_table_anchor[hash_key], found_cred, cr_link);
-                       FREE(cred, M_CRED);
+#if CONFIG_MACF
+                       mac_cred_label_destroy(cred);
+#endif
+                       cred->cr_ref = 0;
+                       FREE_ZONE(cred, sizeof(*cred), M_CRED);
 #if KAUTH_CRED_HASH_DEBUG
                        kauth_cred_count--;
 #endif
@@ -2195,22 +3959,33 @@ kauth_cred_remove(kauth_cred_t cred)
                }
        }
 
-       /* did not find a match.  this should not happen! */
-       printf("%s:%s - %d - %s - did not find a match for 0x%08x\n", __FILE__, __LINE__, __FUNCTION__, current_proc()->p_comm, cred);
+       /* Did not find a match... this should not happen! XXX Make panic? */
+       printf("%s:%d - %s - %s - did not find a match for %p\n", __FILE__, __LINE__, __FUNCTION__, current_proc()->p_comm, cred);
        return;
 }
 
+
 /* 
- *     Using the given credential data, look for a match in our credential hash
- *     table.
- *     NOTE - expects caller to hold KAUTH_CRED_HASH_LOCK!
+ * kauth_cred_find
+ *
+ * Description:        Using the given credential data, look for a match in our
+ *             credential hash table
+ *
+ * Parameters: cred                            Credential to lookup in cred
+ *                                             hash cache
+ *
+ * Returns:    NULL                            Not found
+ *             !NULL                           Matching cedential already in
+ *                                             cred hash cache
+ *
+ * Locks:      Caller is expected to hold KAUTH_CRED_HASH_LOCK
  */
 kauth_cred_t
 kauth_cred_find(kauth_cred_t cred)
 {
        u_long                  hash_key;
        kauth_cred_t    found_cred;
-       
+
        KAUTH_CRED_HASH_LOCK_ASSERT();
 
 #if KAUTH_CRED_HASH_DEBUG
@@ -2225,35 +4000,52 @@ kauth_cred_find(kauth_cred_t cred)
        hash_key = kauth_cred_get_hashkey(cred);
        hash_key %= kauth_cred_table_size;
 
-       /* find cred in the credential hash table */
+       /* Find cred in the credential hash table */
        TAILQ_FOREACH(found_cred, &kauth_cred_table_anchor[hash_key], cr_link) {
-               if (bcmp(&found_cred->cr_uid, &cred->cr_uid, (sizeof(struct ucred) - offsetof(struct ucred, cr_uid))) == 0) {
+               boolean_t match;
+
+               /*
+                * don't worry about the label unless the flags in
+                * either credential tell us to.
+                */
+               if ((found_cred->cr_flags & CRF_MAC_ENFORCE) != 0 ||
+                   (cred->cr_flags & CRF_MAC_ENFORCE) != 0) {
+                       /* include the label pointer in the compare */
+                       match = (bcmp(&found_cred->cr_uid, &cred->cr_uid,
+                                (sizeof(struct ucred) -
+                                 offsetof(struct ucred, cr_uid))) == 0);
+               } else {
+                       /* flags have to match, but skip the label in bcmp */
+                       match = (found_cred->cr_flags == cred->cr_flags &&
+                                bcmp(&found_cred->cr_uid, &cred->cr_uid,
+                                     (offsetof(struct ucred, cr_label) -
+                                      offsetof(struct ucred, cr_uid))) == 0);
+               }
+               if (match) {
                        /* found a match */
                        return(found_cred);
                }
        }
-       /* no match found */
+       /* No match found */
+
        return(NULL);
 }
 
-/*
- * Generates a hash key using data that makes up a credential.  Based on ElfHash.
- */
-static u_long
-kauth_cred_get_hashkey(kauth_cred_t cred)
-{
-       u_long  hash_key = 0;
-       
-       hash_key = kauth_cred_hash((uint8_t *)&cred->cr_uid, 
-                                  (sizeof(struct ucred) - offsetof(struct ucred, cr_uid)), 
-                                                          hash_key);
-       return(hash_key);
-}
 
 /*
- * Generates a hash key using data that makes up a credential.  Based on ElfHash.
+ * kauth_cred_hash
+ *
+ * Description:        Generates a hash key using data that makes up a credential;
+ *             based on ElfHash
+ *
+ * Parameters: datap                           Pointer to data to hash
+ *             data_len                        Count of bytes to hash
+ *             start_key                       Start key value
+ *
+ * Returns:    (u_long)                        Returned hash key
  */
-static inline u_long kauth_cred_hash(const uint8_t *datap, int data_len, u_long start_key)
+static inline u_long
+kauth_cred_hash(const uint8_t *datap, int data_len, u_long start_key)
 {
        u_long  hash_key = start_key;
        u_long  temp;
@@ -2270,8 +4062,52 @@ static inline u_long kauth_cred_hash(const uint8_t *datap, int data_len, u_long
        return(hash_key);
 }
 
+
+/*
+ * kauth_cred_get_hashkey
+ *
+ * Description:        Generate a hash key using data that makes up a credential;
+ *             based on ElfHash.  We hash on the entire credential data,
+ *             not including the ref count or the TAILQ, which are mutable;
+ *             everything else isn't.
+ *
+ *             We also avoid the label (if the flag is not set saying the
+ *             label is actually enforced).
+ *
+ * Parameters: cred                            Credential for which hash is
+ *                                             desired
+ *
+ * Returns:    (u_long)                        Returned hash key
+ */
+static u_long
+kauth_cred_get_hashkey(kauth_cred_t cred)
+{
+       u_long  hash_key = 0;
+       
+       hash_key = kauth_cred_hash((uint8_t *)&cred->cr_uid, 
+                       ((cred->cr_flags & CRF_MAC_ENFORCE) ? 
+                           sizeof(struct ucred) : offsetof(struct ucred, cr_label)) -
+                           offsetof(struct ucred, cr_uid),
+                       hash_key);
+       return(hash_key);
+}
+
+
 #if KAUTH_CRED_HASH_DEBUG
-static void kauth_cred_hash_print(void) 
+/*
+ * kauth_cred_hash_print
+ *
+ * Description:        Print out cred hash cache table information for debugging
+ *             purposes, including the credential contents
+ *
+ * Parameters: (void)
+ *
+ * Returns:    (void)
+ *
+ * Implicit returns:   Results in console output
+ */
+static void
+kauth_cred_hash_print(void) 
 {
        int                     i, j;
        kauth_cred_t    found_cred;
@@ -2294,21 +4130,289 @@ static void kauth_cred_hash_print(void)
                }
        }
 }
+#endif /* KAUTH_CRED_HASH_DEBUG */
 
 
-static void kauth_cred_print(kauth_cred_t cred) 
+#if (defined(KAUTH_CRED_HASH_DEBUG) && (KAUTH_CRED_HASH_DEBUG != 0)) || defined(DEBUG_CRED)
+/*
+ * kauth_cred_print
+ *
+ * Description:        Print out an individual credential's contents for debugging
+ *             purposes
+ *
+ * Parameters: cred                            The credential to print out
+ *
+ * Returns:    (void)
+ *
+ * Implicit returns:   Results in console output
+ */
+void
+kauth_cred_print(kauth_cred_t cred) 
 {
        int     i;
-       
-       printf("0x%02X - refs %d uids %d %d %d ", cred, cred->cr_ref, cred->cr_uid, cred->cr_ruid, cred->cr_svuid);
+
+       printf("%p - refs %lu flags 0x%08x uids e%d r%d sv%d gm%d ", cred, cred->cr_ref, cred->cr_flags, cred->cr_uid, cred->cr_ruid, cred->cr_svuid, cred->cr_gmuid);
        printf("group count %d gids ", cred->cr_ngroups);
        for (i = 0; i < NGROUPS; i++) {
+               if (i == 0)
+                       printf("e");
                printf("%d ", cred->cr_groups[i]);
        }
-       printf("%d %d %d ", cred->cr_rgid, cred->cr_svgid, cred->cr_gmuid);
-       printf("auditinfo %d %d %d %d %d %d ", 
+       printf("r%d sv%d ", cred->cr_rgid, cred->cr_svgid);
+       printf("auditinfo %d %d %d %d %d %d\n", 
                cred->cr_au.ai_auid, cred->cr_au.ai_mask.am_success, cred->cr_au.ai_mask.am_failure, 
                cred->cr_au.ai_termid.port, cred->cr_au.ai_termid.machine, cred->cr_au.ai_asid);
+}
+
+int is_target_cred( kauth_cred_t the_cred )
+{
+       if ( the_cred->cr_uid != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_ruid != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_svuid != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_ngroups != 11 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[0] != 11 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[1] != 81 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[2] != 63947 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[3] != 80288 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[4] != 89006 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[5] != 52173 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[6] != 84524 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[7] != 79 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[8] != 80292 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[9] != 80 ) 
+               return( 0 );
+       if ( the_cred->cr_groups[10] != 90824 ) 
+               return( 0 );
+       if ( the_cred->cr_rgid != 11 ) 
+               return( 0 );
+       if ( the_cred->cr_svgid != 11 ) 
+               return( 0 );
+       if ( the_cred->cr_gmuid != 3475 ) 
+               return( 0 );
+       if ( the_cred->cr_au.ai_auid != 3475 ) 
+               return( 0 );
+/*
+       if ( the_cred->cr_au.ai_mask.am_success != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_au.ai_mask.am_failure != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_au.ai_termid.port != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_au.ai_termid.machine != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_au.ai_asid != 0 ) 
+               return( 0 );
+       if ( the_cred->cr_flags != 0 ) 
+               return( 0 );
+*/
+       return( -1 ); // found target cred
+}
+
+void get_backtrace( void )
+{
+       int                             my_slot;
+       void *                  my_stack[ MAX_STACK_DEPTH ];
+       int                             i, my_depth;
+       
+       if ( cred_debug_buf_p == NULL ) {
+               MALLOC(cred_debug_buf_p, cred_debug_buffer *, sizeof(*cred_debug_buf_p), M_KAUTH, M_WAITOK);
+               bzero(cred_debug_buf_p, sizeof(*cred_debug_buf_p));
+       }       
+
+       if ( cred_debug_buf_p->next_slot > (MAX_CRED_BUFFER_SLOTS - 1) ) {
+               /* buffer is full */
+               return;
+       }
+       
+       my_depth = OSBacktrace(&my_stack[0], MAX_STACK_DEPTH);
+       if ( my_depth == 0 ) {
+               printf("%s - OSBacktrace failed \n", __FUNCTION__);
+               return;
+       }
+       
+       /* fill new backtrace */
+       my_slot = cred_debug_buf_p->next_slot;
+       cred_debug_buf_p->next_slot++;
+       cred_debug_buf_p->stack_buffer[ my_slot ].depth = my_depth;
+       for ( i = 0; i < my_depth; i++ ) {
+               cred_debug_buf_p->stack_buffer[ my_slot ].stack[ i ] = my_stack[ i ];
+       }
+
+       return;
+}
+
+
+/* subset of struct ucred for use in sysctl_dump_creds */
+struct debug_ucred {
+       void    *credp;
+       u_long  cr_ref;                         /* reference count */
+       uid_t   cr_uid;                         /* effective user id */
+       uid_t   cr_ruid;                        /* real user id */
+       uid_t   cr_svuid;                       /* saved user id */
+       short   cr_ngroups;                     /* number of groups in advisory list */
+       gid_t   cr_groups[NGROUPS];     /* advisory group list */
+       gid_t   cr_rgid;                        /* real group id */
+       gid_t   cr_svgid;                       /* saved group id */
+       uid_t   cr_gmuid;                       /* UID for group membership purposes */
+       struct auditinfo cr_au;         /* user auditing data */
+       void    *cr_label;                      /* MACF label */
+       int             cr_flags;                       /* flags on credential */
+};
+typedef struct debug_ucred debug_ucred;
+
+SYSCTL_PROC(_kern, OID_AUTO, dump_creds, CTLFLAG_RD,
+    NULL, 0, sysctl_dump_creds, "S,debug_ucred", "List of credentials in the cred hash");
+
+/*     accessed by:      
+ *     err = sysctlbyname( "kern.dump_creds", bufp, &len, NULL, 0 );
+ */
+
+static int
+sysctl_dump_creds( __unused struct sysctl_oid *oidp, __unused void *arg1, __unused int arg2, struct sysctl_req *req )
+{
+       int                     i, j, counter = 0;
+       int                             error;
+       size_t                  space;
+       kauth_cred_t    found_cred;
+       debug_ucred *   cred_listp;
+       debug_ucred *   nextp;
+
+       /* This is a readonly node. */
+       if (req->newptr != USER_ADDR_NULL)
+               return (EPERM);
+
+       /* calculate space needed */
+       for (i = 0; i < kauth_cred_table_size; i++) {
+               TAILQ_FOREACH(found_cred, &kauth_cred_table_anchor[i], cr_link) {
+                       counter++;
+               }
+       }
+
+       /* they are querying us so just return the space required. */
+       if (req->oldptr == USER_ADDR_NULL) {
+               counter += 10; // add in some padding;
+               req->oldidx = counter * sizeof(debug_ucred);
+               return 0;
+       }
+
+       MALLOC( cred_listp, debug_ucred *, req->oldlen, M_TEMP, M_WAITOK );
+       if ( cred_listp == NULL ) {
+               return (ENOMEM);
+       }
+       
+       /* fill in creds to send back */
+       nextp = cred_listp;
+       space = 0;
+       for (i = 0; i < kauth_cred_table_size; i++) {
+               TAILQ_FOREACH(found_cred, &kauth_cred_table_anchor[i], cr_link) {
+                       nextp->credp = found_cred;
+                       nextp->cr_ref = found_cred->cr_ref;
+                       nextp->cr_uid = found_cred->cr_uid;
+                       nextp->cr_ruid = found_cred->cr_ruid;
+                       nextp->cr_svuid = found_cred->cr_svuid;
+                       nextp->cr_ngroups = found_cred->cr_ngroups;
+                       for ( j = 0; j < nextp->cr_ngroups; j++ ) {
+                               nextp->cr_groups[ j ] = found_cred->cr_groups[ j ];
+                       }
+                       nextp->cr_rgid = found_cred->cr_rgid;
+                       nextp->cr_svgid = found_cred->cr_svgid;
+                       nextp->cr_gmuid = found_cred->cr_gmuid;
+                       nextp->cr_au.ai_auid = found_cred->cr_au.ai_auid;
+                       nextp->cr_au.ai_mask.am_success = found_cred->cr_au.ai_mask.am_success;
+                       nextp->cr_au.ai_mask.am_failure = found_cred->cr_au.ai_mask.am_failure;
+                       nextp->cr_au.ai_termid.port = found_cred->cr_au.ai_termid.port;
+                       nextp->cr_au.ai_termid.machine = found_cred->cr_au.ai_termid.machine;
+                       nextp->cr_au.ai_asid = found_cred->cr_au.ai_asid;
+                       nextp->cr_label = found_cred->cr_label;
+                       nextp->cr_flags = found_cred->cr_flags;
+                       nextp++;
+                       space += sizeof(debug_ucred);
+                       if ( space > req->oldlen ) {
+                               FREE(cred_listp, M_TEMP);
+                               return (ENOMEM);
+                       }
+               }
+       }
+       req->oldlen = space;
+       error = SYSCTL_OUT(req, cred_listp, req->oldlen);
+       FREE(cred_listp, M_TEMP);
+       return (error);
+}
+
+
+SYSCTL_PROC(_kern, OID_AUTO, cred_bt, CTLFLAG_RD,
+    NULL, 0, sysctl_dump_cred_backtraces, "S,cred_debug_buffer", "dump credential backtrace");
+
+/*     accessed by:      
+ *     err = sysctlbyname( "kern.cred_bt", bufp, &len, NULL, 0 );
+ */
+
+static int
+sysctl_dump_cred_backtraces( __unused struct sysctl_oid *oidp, __unused void *arg1, __unused int arg2, struct sysctl_req *req )
+{
+       int                     i, j;
+       int                             error;
+       size_t                  space;
+       cred_debug_buffer *     bt_bufp;
+       cred_backtrace *        nextp;
+
+       /* This is a readonly node. */
+       if (req->newptr != USER_ADDR_NULL)
+               return (EPERM);
+
+       if ( cred_debug_buf_p == NULL ) {
+               return (EAGAIN);
+       }
+
+       /* calculate space needed */
+       space = sizeof( cred_debug_buf_p->next_slot );
+       space += (sizeof( cred_backtrace ) * cred_debug_buf_p->next_slot);
+
+       /* they are querying us so just return the space required. */
+       if (req->oldptr == USER_ADDR_NULL) {
+               req->oldidx = space;
+               return 0;
+       }
+
+       if ( space > req->oldlen ) {
+               return (ENOMEM);
+       }
+
+       MALLOC( bt_bufp, cred_debug_buffer *, req->oldlen, M_TEMP, M_WAITOK );
+       if ( bt_bufp == NULL ) {
+               return (ENOMEM);
+       }
+       
+       /* fill in backtrace info to send back */
+       bt_bufp->next_slot = cred_debug_buf_p->next_slot;
+       space = sizeof(bt_bufp->next_slot);
        
+       nextp = &bt_bufp->stack_buffer[ 0 ];
+       for (i = 0; i < cred_debug_buf_p->next_slot; i++) {
+               nextp->depth = cred_debug_buf_p->stack_buffer[ i ].depth;
+               for ( j = 0; j < nextp->depth; j++ ) {
+                       nextp->stack[ j ] = cred_debug_buf_p->stack_buffer[ i ].stack[ j ];
+               }
+               space += sizeof(*nextp);
+               nextp++;
+       }
+       req->oldlen = space;
+       error = SYSCTL_OUT(req, bt_bufp, req->oldlen);
+       FREE(bt_bufp, M_TEMP);
+       return (error);
 }
-#endif
+
+#endif /* KAUTH_CRED_HASH_DEBUG || DEBUG_CRED */