]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/kern/kern_authorization.c
xnu-2422.110.17.tar.gz
[apple/xnu.git] / bsd / kern / kern_authorization.c
index e7410c57b35c097204891b5a47739bad62582f7a..91c2305c8a9274e023d57d1ec35bfe9cb95d0dee 100644 (file)
@@ -1,14 +1,19 @@
 /*
- * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2004-2011 Apple Inc. All rights reserved.
  *
- * @APPLE_LICENSE_HEADER_START@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
  * 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. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
+ * 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.
+ * 
+ * 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
@@ -18,7 +23,7 @@
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * 
- * @APPLE_LICENSE_HEADER_END@
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 
 /*
@@ -38,7 +43,7 @@
 #include <sys/kauth.h>
 #include <sys/stat.h>
 
-#include <bsm/audit_kernel.h>
+#include <security/audit/audit.h>
 
 #include <sys/mount.h>
 #include <sys/sysproto.h>
@@ -127,7 +132,7 @@ static int  kauth_authorize_generic_callback(kauth_cred_t _credential, void *_ida
     uintptr_t arg0, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3);
 kauth_scope_t  kauth_scope_fileop;
 
-extern int             cansignal(struct proc *, kauth_cred_t, struct proc *, int);
+extern int             cansignal(struct proc *, kauth_cred_t, struct proc *, int, int);
 extern char *  get_pathbuff(void);
 extern void            release_pathbuff(char *path);
 
@@ -149,11 +154,14 @@ kauth_init(void)
 
        /* bring up kauth subsystem components */
        kauth_cred_init();
+#if CONFIG_EXT_RESOLVER
        kauth_identity_init();
        kauth_groups_init();
+#endif
        kauth_scope_init();
+#if CONFIG_EXT_RESOLVER
        kauth_resolver_init();
-
+#endif
        /* can't alloc locks after this */
        lck_grp_free(kauth_lck_grp);
        kauth_lck_grp = NULL;
@@ -180,10 +188,9 @@ kauth_alloc_scope(const char *identifier, kauth_scope_callback_t callback, void
        /*
         * Allocate and populate the scope structure.
         */
-       MALLOC(sp, kauth_scope_t, sizeof(*sp), M_KAUTH, M_WAITOK);
+       MALLOC(sp, kauth_scope_t, sizeof(*sp), M_KAUTH, M_WAITOK | M_ZERO);
        if (sp == NULL)
                return(NULL);
-       bzero(&sp->ks_listeners, sizeof(sp->ks_listeners));
        sp->ks_flags = 0;
        sp->ks_identifier = identifier;
        sp->ks_idata = idata;
@@ -223,7 +230,8 @@ kauth_register_scope(const char *identifier, kauth_scope_callback_t callback, vo
        KAUTH_SCOPELOCK();
        TAILQ_FOREACH(tsp, &kauth_scopes, ks_link) {
                /* duplicate! */
-               if (strcmp(tsp->ks_identifier, identifier) == 0) {
+               if (strncmp(tsp->ks_identifier, identifier, 
+                                       strlen(tsp->ks_identifier) + 1) == 0) {
                        KAUTH_SCOPEUNLOCK();
                        FREE(sp, M_KAUTH);
                        return(NULL);
@@ -239,7 +247,8 @@ kauth_register_scope(const char *identifier, kauth_scope_callback_t callback, vo
         */
 restart:
        TAILQ_FOREACH(klp, &kauth_dangling_listeners, kl_link) {
-               if (strcmp(klp->kl_identifier, sp->ks_identifier) == 0) {
+               if (strncmp(klp->kl_identifier, sp->ks_identifier,
+                                       strlen(klp->kl_identifier) + 1) == 0) {
                        /* found a match on the dangling listener list.  add it to the
                         * the active scope.
                         */
@@ -302,7 +311,8 @@ kauth_listen_scope(const char *identifier, kauth_scope_callback_t callback, void
         */
        KAUTH_SCOPELOCK();
        TAILQ_FOREACH(sp, &kauth_scopes, ks_link) {
-               if (strcmp(sp->ks_identifier, identifier) == 0) {
+               if (strncmp(sp->ks_identifier, identifier,
+                                       strlen(sp->ks_identifier) + 1) == 0) {
                        /* scope exists, add it to scope listener table */
                        if (kauth_add_callback_to_scope(sp, klp) == 0) {
                                KAUTH_SCOPEUNLOCK();
@@ -377,6 +387,12 @@ kauth_unlisten_scope(kauth_listener_t listener)
 
 /*
  * Authorization requests.
+ *
+ * Returns:    0                       Success
+ *             EPERM                   Operation not permitted
+ *
+ * Imputed:    *arg3, modified         Callback return - depends on callback
+ *                                     modification of *arg3, if any
  */
 int
 kauth_authorize_action(kauth_scope_t scope, kauth_cred_t credential, kauth_action_t action,
@@ -468,7 +484,7 @@ kauth_authorize_process_callback(kauth_cred_t credential, __unused void *idata,
                /* arg0 - process to signal
                 * arg1 - signal to send the process
                 */
-               if (cansignal(current_proc(), credential, (struct proc *)arg0, (int)arg1))
+               if (cansignal(current_proc(), credential, (struct proc *)arg0, (int)arg1, 0))
                        return(KAUTH_RESULT_ALLOW);
                break;
        case KAUTH_PROCESS_CANTRACE:
@@ -599,7 +615,7 @@ kauth_authorize_generic_callback(kauth_cred_t credential, __unused void *idata,
 int
 kauth_acl_evaluate(kauth_cred_t cred, kauth_acl_eval_t eval)
 {
-       int applies, error, i;
+       int applies, error, i, gotguid;
        kauth_ace_t ace;
        guid_t guid;
        uint32_t rights;
@@ -612,14 +628,17 @@ kauth_acl_evaluate(kauth_cred_t cred, kauth_acl_eval_t eval)
        }
 
        eval->ae_residual = eval->ae_requested;
+       eval->ae_found_deny = FALSE;
 
        /*
         * Get our guid for comparison purposes.
         */
        if ((error = kauth_cred_getguid(cred, &guid)) != 0) {
-               eval->ae_result = KAUTH_RESULT_DENY;
-               KAUTH_DEBUG("    ACL - can't get credential GUID (%d), ACL denied", error);
-               return(error);
+               KAUTH_DEBUG("    ACL - can't get credential GUID (%d)", error);
+               error = 0;
+               gotguid = 0;
+       } else {
+               gotguid = 1;
        }
 
        KAUTH_DEBUG("    ACL - %d entries, initial residual %x", eval->ae_count, eval->ae_residual);
@@ -657,12 +676,13 @@ kauth_acl_evaluate(kauth_cred_t cred, kauth_acl_eval_t eval)
                case KAUTH_ACE_DENY:
                        if (!(eval->ae_requested & rights))
                                continue;
+                       eval->ae_found_deny = TRUE;
                        break;
                default:
                        /* we don't recognise this ACE, skip it */
                        continue;
                }
-               
+       
                /*
                 * Verify whether this entry applies to the credential.
                 */
@@ -672,7 +692,10 @@ kauth_acl_evaluate(kauth_cred_t cred, kauth_acl_eval_t eval)
                        applies = eval->ae_options & KAUTH_AEVAL_IS_OWNER;
                        break;
                case KAUTH_WKG_GROUP:
-                       applies = eval->ae_options & KAUTH_AEVAL_IN_GROUP;
+                       if (!gotguid || (eval->ae_options & KAUTH_AEVAL_IN_GROUP_UNKNOWN))
+                               applies = ((ace->ace_flags & KAUTH_ACE_KINDMASK) == KAUTH_ACE_DENY);
+                       else
+                               applies = eval->ae_options & KAUTH_AEVAL_IN_GROUP;
                        break;
                /* we short-circuit these here rather than wasting time calling the group membership code */
                case KAUTH_WKG_EVERYBODY:
@@ -684,12 +707,12 @@ kauth_acl_evaluate(kauth_cred_t cred, kauth_acl_eval_t eval)
 
                default:
                        /* check to see whether it's exactly us, or a group we are a member of */
-                       applies = kauth_guid_equal(&guid, &ace->ace_applicable);
+                       applies = !gotguid ? 0 : kauth_guid_equal(&guid, &ace->ace_applicable);
                        KAUTH_DEBUG("    ACL - ACE applicable " K_UUID_FMT " caller " K_UUID_FMT " %smatched",
                            K_UUID_ARG(ace->ace_applicable), K_UUID_ARG(guid), applies ? "" : "not ");
                
                        if (!applies) {
-                               error = kauth_cred_ismember_guid(cred, &ace->ace_applicable, &applies);
+                               error = !gotguid ? ENOENT : kauth_cred_ismember_guid(cred, &ace->ace_applicable, &applies);
                                /*
                                 * If we can't resolve group membership, we have to limit misbehaviour.
                                 * If the ACE is an 'allow' ACE, assume the cred is not a member (avoid
@@ -766,24 +789,51 @@ kauth_acl_inherit(vnode_t dvp, kauth_acl_t initial, kauth_acl_t *product, int is
        kauth_acl_t inherit, result;
 
        /*
-        * Fetch the ACL from the directory.  This should never fail.  Note that we don't
-        * manage inheritance when the remote server is doing authorization; we just
-        * want to compose the umask-ACL and any initial ACL.
+        * Fetch the ACL from the directory.  This should never fail.
+        * Note that we don't manage inheritance when the remote server is
+        * doing authorization, since this means server enforcement of
+        * inheritance semantics; we just want to compose the initial
+        * ACL and any inherited ACE entries from the container object.
+        *
+        * XXX TODO: <rdar://3634665> wants a "umask ACL" from the process.
         */
        inherit = NULL;
-       if ((dvp != NULL) && !vfs_authopaque(vnode_mount(dvp))) {
+       /*
+        * If there is no initial ACL, or there is, and the initial ACLs
+        * flags do not request "no inheritance", then we inherit.  This allows
+        * initial object creation via open_extended() and mkdir_extended()
+        * to reject inheritance for themselves and for inferior nodes by
+        * specifying a non-NULL inital ACL which has the KAUTH_ACL_NO_INHERIT
+        * flag set in the flags field.
+        */
+       if ((initial == NULL || !(initial->acl_flags & KAUTH_ACL_NO_INHERIT)) &&
+           (dvp != NULL) && !vfs_authopaque(vnode_mount(dvp))) {
                VATTR_INIT(&dva);
                VATTR_WANTED(&dva, va_acl);
                if ((error = vnode_getattr(dvp, &dva, ctx)) != 0) {
                        KAUTH_DEBUG("    ERROR - could not get parent directory ACL for inheritance");
                        return(error);
                }
-               if (VATTR_IS_SUPPORTED(&dva, va_acl))
+               if (VATTR_IS_SUPPORTED(&dva, va_acl)) {
                        inherit = dva.va_acl;
+                       /*
+                        * If there is an ACL on the parent directory, then
+                        * there are potentially inheritable ACE entries, but
+                        * if the flags on the directory ACL say not to
+                        * inherit, then we don't inherit.  This allows for
+                        * per directory rerooting of the inheritable ACL
+                        * hierarchy.
+                        */
+                       if (inherit != NULL && inherit->acl_flags & KAUTH_ACL_NO_INHERIT) {
+                               kauth_acl_free(inherit);
+                               inherit = NULL;
+                       }
+               }
        }
 
        /*
-        * Compute the number of entries in the result ACL by scanning the input lists.
+        * Compute the number of entries in the result ACL by scanning the
+        * input lists.
         */
        entries = 0;
        if (inherit != NULL) {
@@ -794,16 +844,23 @@ kauth_acl_inherit(vnode_t dvp, kauth_acl_t initial, kauth_acl_t *product, int is
        }
 
        if (initial == NULL) {
-               /* XXX 3634665 TODO: fetch umask ACL from the process, set in initial */
+               /*
+                * XXX 3634665 TODO: if the initial ACL is not specfied by
+                * XXX the caller, fetch the umask ACL from the process,
+                * and use it in place of "initial".
+                */
        }
 
        if (initial != NULL) {
-               entries += initial->acl_entrycount;
+               if (initial->acl_entrycount != KAUTH_FILESEC_NOACL)
+                       entries += initial->acl_entrycount;
+               else
+                       initial = NULL;
        }
 
        /*
         * If there is no initial ACL, and no inheritable entries, the
-        * object should have no ACL at all.
+        * object should be created with no ACL at all.
         * Note that this differs from the case where the initial ACL
         * is empty, in which case the object must also have an empty ACL.
         */
@@ -817,32 +874,49 @@ kauth_acl_inherit(vnode_t dvp, kauth_acl_t initial, kauth_acl_t *product, int is
         * Allocate the result buffer.
         */
        if ((result = kauth_acl_alloc(entries)) == NULL) {
-               KAUTH_DEBUG("    ERROR - could not allocate %d-entry result buffer for inherited ACL");
+               KAUTH_DEBUG("    ERROR - could not allocate %d-entry result buffer for inherited ACL", entries);
                error = ENOMEM;
                goto out;
        }
 
        /*
         * Composition is simply:
-        *  - initial
-        *  - inherited
+        *  - initial direct ACEs
+        *  - inherited ACEs from new parent
         */
        index = 0;
        if (initial != NULL) {
-               for (i = 0; i < initial->acl_entrycount; i++)
-                       result->acl_ace[index++] = initial->acl_ace[i];
-               KAUTH_DEBUG("    INHERIT - applied %d initial entries", index);
+               for (i = 0; i < initial->acl_entrycount; i++) {
+                       if (!(initial->acl_ace[i].ace_flags & KAUTH_ACE_INHERITED)) {
+                               result->acl_ace[index++] = initial->acl_ace[i];
+                       }
+               }
+               KAUTH_DEBUG("    INHERIT - applied %d of %d initial entries", index, initial->acl_entrycount);
        }
        if (inherit != NULL) {
                for (i = 0; i < inherit->acl_entrycount; i++) {
-                       /* inherit onto this object? */
+                       /*
+                        * Inherit onto this object?  We inherit only if
+                        * the target object is a container object and the
+                        * KAUTH_ACE_DIRECTORY_INHERIT bit is set, OR if
+                        * if the target object is not a container, and
+                        * the KAUTH_ACE_FILE_INHERIT bit is set.
+                        */
                        if (inherit->acl_ace[i].ace_flags & (isdir ? KAUTH_ACE_DIRECTORY_INHERIT : KAUTH_ACE_FILE_INHERIT)) {
                                result->acl_ace[index] = inherit->acl_ace[i];
                                result->acl_ace[index].ace_flags |= KAUTH_ACE_INHERITED;
-                               /* don't re-inherit? */
-                               if (result->acl_ace[index].ace_flags & KAUTH_ACE_LIMIT_INHERIT)
+                               result->acl_ace[index].ace_flags &= ~KAUTH_ACE_ONLY_INHERIT;
+                               /*
+                                * We do not re-inherit inheritance flags
+                                * if the ACE from the container has a
+                                * KAUTH_ACE_LIMIT_INHERIT, OR if the new
+                                * object is not itself a container (since
+                                * inheritance is always container-based).
+                                */
+                               if ((result->acl_ace[index].ace_flags & KAUTH_ACE_LIMIT_INHERIT) || !isdir) {
                                        result->acl_ace[index].ace_flags &=
-                                           ~(KAUTH_ACE_DIRECTORY_INHERIT | KAUTH_ACE_FILE_INHERIT | KAUTH_ACE_LIMIT_INHERIT);
+                                           ~(KAUTH_ACE_INHERIT_CONTROL_FLAGS);
+                               }
                                index++;
                        }
                }
@@ -859,14 +933,32 @@ out:
 
 /*
  * Optimistically copy in a kauth_filesec structure
+ *
  * Parameters: xsecurity               user space kauth_filesec_t
- *             xsecdstpp               pointer to kauth_filesec_t
+ *             xsecdstpp               pointer to kauth_filesec_t to be
+ *                                     modified to contain the contain a
+ *                                     pointer to an allocated copy of the
+ *                                     user space argument
+ *
+ * Returns:    0                       Success
+ *             ENOMEM                  Insufficient memory for the copy.
+ *             EINVAL                  The user space data was invalid, or
+ *                                     there were too many ACE entries.
+ *             EFAULT                  The user space address was invalid;
+ *                                     this may mean 'fsec_entrycount' in
+ *                                     the user copy is corrupt/incorrect.
+ *
+ * Implicit returns: xsecdestpp, modified (only if successful!)
+ *
+ * Notes:      The returned kauth_filesec_t is in host byte order
  *
- * Returns: 0 on success, EINVAL or EFAULT depending on failure mode.
- * Modifies: xsecdestpp, which contains a pointer to an allocated
- *          and copied-in kauth_filesec_t
+ *             The caller is responsible for freeing the returned
+ *             kauth_filesec_t in the success case using the function
+ *             kauth_filesec_free()
+ *
+ *             Our largest initial guess is 32; this needs to move to
+ *             a manifest constant in <sys/kauth.h>.
  */
-
 int
 kauth_copyinfilesec(user_addr_t xsecurity, kauth_filesec_t *xsecdestpp)
 {
@@ -888,7 +980,7 @@ kauth_copyinfilesec(user_addr_t xsecurity, kauth_filesec_t *xsecdestpp)
         * The upper bound must be less than KAUTH_ACL_MAX_ENTRIES.  The
         * value here is fairly arbitrary.  It's ok to have a zero count.
         */
-       known_bound = xsecurity + sizeof(struct kauth_filesec);
+       known_bound = xsecurity +  KAUTH_FILESEC_SIZE(0);
        uaddr = mach_vm_round_page(known_bound);
        count = (uaddr - known_bound) / sizeof(struct kauth_ace);
        if (count > 32)
@@ -914,6 +1006,7 @@ restart:
        if ((fsec->fsec_entrycount != KAUTH_FILESEC_NOACL) &&
            (fsec->fsec_entrycount > count)) {
                if (fsec->fsec_entrycount > KAUTH_ACL_MAX_ENTRIES) {
+                       /* XXX This should be E2BIG */
                        error = EINVAL;
                        goto out;
                }
@@ -928,12 +1021,29 @@ out:
                        kauth_filesec_free(fsec);
        } else {
                *xsecdestpp = fsec;
+               AUDIT_ARG(opaque, fsec, copysize);
        }
        return(error);
 }
 
 /*
- * Allocate a filesec structure.
+ * Allocate a block of memory containing a filesec structure, immediately
+ * followed by 'count' kauth_ace structures.
+ *
+ * Parameters: count                   Number of kauth_ace structures needed
+ *
+ * Returns:    !NULL                   A pointer to the allocated block
+ *             NULL                    Invalid 'count' or insufficient memory
+ *
+ * Notes:      Returned memory area assumes that the structures are packed
+ *             densely, so this function may only be used by code that also
+ *             assumes no padding following structures.
+ *
+ *             The returned structure must be freed by the caller using the
+ *             function kauth_filesec_free(), in case we decide to use an
+ *             allocation mechanism that is aware of the object size at some
+ *             point, since the object size is only available by introspecting
+ *             the object itself.
  */
 kauth_filesec_t
 kauth_filesec_alloc(int count)
@@ -955,6 +1065,18 @@ kauth_filesec_alloc(int count)
        return(fsp);
 }      
 
+/*
+ * Free a kauth_filesec_t that was previous allocated, either by a direct
+ * call to kauth_filesec_alloc() or by calling a function that calls it.
+ *
+ * Parameters: fsp                     kauth_filesec_t to free
+ *
+ * Returns:    (void)
+ *
+ * Notes:      The kauth_filesec_t to be freed is assumed to be in host
+ *             byte order so that this function can introspect it in the
+ *             future to determine its size, if necesssary.
+ */
 void
 kauth_filesec_free(kauth_filesec_t fsp)
 {
@@ -967,6 +1089,73 @@ kauth_filesec_free(kauth_filesec_t fsp)
        FREE(fsp, M_KAUTH);
 }
 
+/*
+ * Set the endianness of a filesec and an ACL; if 'acl' is NULL, use the 
+ * ACL interior to 'fsec' instead.  If the endianness doesn't change, then
+ * this function will have no effect.
+ *
+ * Parameters: kendian                 The endianness to set; this is either
+ *                                     KAUTH_ENDIAN_HOST or KAUTH_ENDIAN_DISK.
+ *             fsec                    The filesec to convert.
+ *             acl                     The ACL to convert (optional)
+ *
+ * Returns:    (void)
+ *
+ * Notes:      We use ntohl() because it has a transitive property on Intel
+ *             machines and no effect on PPC mancines.  This guarantees us
+ *             that the swapping only occurs if the endiannes is wrong.
+ */
+void
+kauth_filesec_acl_setendian(int kendian, kauth_filesec_t fsec, kauth_acl_t acl)
+{
+       uint32_t        compare_magic = KAUTH_FILESEC_MAGIC;
+       uint32_t        invert_magic = ntohl(KAUTH_FILESEC_MAGIC);
+       uint32_t        compare_acl_entrycount;
+       uint32_t        i;
+
+       if (compare_magic == invert_magic)
+               return;
+
+       /* If no ACL, use ACL interior to 'fsec' instead */
+       if (acl == NULL)
+               acl = &fsec->fsec_acl;
+
+       compare_acl_entrycount = acl->acl_entrycount;
+
+       /*
+        * Only convert what needs to be converted, and only if the arguments
+        * are valid.  The following switch and tests effectively reject
+        * conversions on invalid magic numbers as a desirable side effect.
+        */
+       switch(kendian) {
+       case KAUTH_ENDIAN_HOST:         /* not in host, convert to host */
+               if (fsec->fsec_magic != invert_magic)
+                       return;
+               /* acl_entrycount is byteswapped */
+               compare_acl_entrycount = ntohl(acl->acl_entrycount);
+               break;
+       case KAUTH_ENDIAN_DISK:         /* not in disk, convert to disk */
+               if (fsec->fsec_magic != compare_magic)
+                       return;
+               break;
+       default:                        /* bad argument */
+               return;
+       }
+       
+       /* We are go for conversion */
+       fsec->fsec_magic = ntohl(fsec->fsec_magic);
+       acl->acl_entrycount = ntohl(acl->acl_entrycount);
+       if (compare_acl_entrycount != KAUTH_FILESEC_NOACL) {
+               acl->acl_flags = ntohl(acl->acl_flags);
+
+               /* swap ACE rights and flags */
+               for (i = 0; i < compare_acl_entrycount; i++) {
+                       acl->acl_ace[i].ace_flags = ntohl(acl->acl_ace[i].ace_flags);
+                       acl->acl_ace[i].ace_rights = ntohl(acl->acl_ace[i].ace_rights);
+               }
+       }
+ }
+
 
 /*
  * Allocate an ACL buffer.