xnu-4570.61.1.tar.gz

[apple/xnu.git] / bsd / security / audit / audit_bsd.c

/*-
 * Copyright (c) 2008-2010 Apple Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <string.h>

#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/systm.h>

#include <kern/host.h>
#include <kern/kalloc.h>
#include <kern/locks.h>
#include <kern/sched_prim.h>

#include <libkern/OSAtomic.h>

#include <bsm/audit.h>
#include <bsm/audit_internal.h>

#include <security/audit/audit_bsd.h>
#include <security/audit/audit.h>
#include <security/audit/audit_private.h>

#include <mach/host_priv.h>
#include <mach/host_special_ports.h>
#include <mach/audit_triggers_server.h>

#include <os/overflow.h>

extern void ipc_port_release_send(ipc_port_t port);

#if CONFIG_AUDIT
struct mhdr {
        size_t                   mh_size;
        au_malloc_type_t        *mh_type;
        u_long                   mh_magic;
        char                     mh_data[0];
};

/*
 * The lock group for the audit subsystem. 
 */
static lck_grp_t *audit_lck_grp = NULL;

#define AUDIT_MHMAGIC   0x4D656C53

#if AUDIT_MALLOC_DEBUG
#define AU_MAX_SHORTDESC        20
#define AU_MAX_LASTCALLER       20
struct au_malloc_debug_info {
        SInt64          md_size;
        SInt64          md_maxsize;
        SInt32          md_inuse;
        SInt32          md_maxused;
        unsigned        md_type;
        unsigned        md_magic;
        char            md_shortdesc[AU_MAX_SHORTDESC];
        char            md_lastcaller[AU_MAX_LASTCALLER];
};
typedef struct au_malloc_debug_info   au_malloc_debug_info_t;

au_malloc_type_t        *audit_malloc_types[NUM_MALLOC_TYPES];

static int audit_sysctl_malloc_debug(struct sysctl_oid *oidp, void *arg1,
    int arg2, struct sysctl_req *req);

SYSCTL_PROC(_kern, OID_AUTO, audit_malloc_debug, CTLFLAG_RD, NULL, 0,
    audit_sysctl_malloc_debug, "S,audit_malloc_debug",
    "Current malloc debug info for auditing.");

#define AU_MALLOC_DBINFO_SZ \
    (NUM_MALLOC_TYPES * sizeof(au_malloc_debug_info_t))

/*
 * Copy out the malloc debug info via the sysctl interface.  The userland code 
 * is something like the following:
 *
 *  error = sysctlbyname("kern.audit_malloc_debug", buffer_ptr, &buffer_len,
 *             NULL, 0);
 */
static int
audit_sysctl_malloc_debug(__unused struct sysctl_oid *oidp, __unused void *arg1,
    __unused int arg2, struct sysctl_req *req)
{
        int i;
        size_t sz;
        au_malloc_debug_info_t *amdi_ptr, *nxt_ptr;
        int err;

        /*
         * This provides a read-only node.
         */
        if (req->newptr != USER_ADDR_NULL)
                return (EPERM);

        /*
         * If just querying then return the space required. 
         */
        if (req->oldptr == USER_ADDR_NULL) {
                req->oldidx = AU_MALLOC_DBINFO_SZ; 
                return (0);
        }

        /*
         *  Alloc a temporary buffer.
         */
        if (req->oldlen < AU_MALLOC_DBINFO_SZ)
                return (ENOMEM);
        amdi_ptr = (au_malloc_debug_info_t *)kalloc(AU_MALLOC_DBINFO_SZ);
        if (amdi_ptr == NULL)
                return (ENOMEM);
        bzero(amdi_ptr, AU_MALLOC_DBINFO_SZ);

        /*
         * Build the record array. 
         */
        sz = 0;
        nxt_ptr = amdi_ptr;
        for(i = 0; i < NUM_MALLOC_TYPES; i++) {
                if (audit_malloc_types[i] == NULL)
                        continue;
                if (audit_malloc_types[i]->mt_magic != M_MAGIC) {
                        nxt_ptr->md_magic = audit_malloc_types[i]->mt_magic;
                        continue;
                }
                nxt_ptr->md_magic = audit_malloc_types[i]->mt_magic;
                nxt_ptr->md_size = audit_malloc_types[i]->mt_size;
                nxt_ptr->md_maxsize = audit_malloc_types[i]->mt_maxsize;
                nxt_ptr->md_inuse = (int)audit_malloc_types[i]->mt_inuse;
                nxt_ptr->md_maxused = (int)audit_malloc_types[i]->mt_maxused;
                strlcpy(nxt_ptr->md_shortdesc,
                    audit_malloc_types[i]->mt_shortdesc, AU_MAX_SHORTDESC - 1);
                strlcpy(nxt_ptr->md_lastcaller,
                    audit_malloc_types[i]->mt_lastcaller, AU_MAX_LASTCALLER-1);
                sz += sizeof(au_malloc_debug_info_t);
                nxt_ptr++;
        }

        req->oldlen = sz;
        err = SYSCTL_OUT(req, amdi_ptr, sz);
        kfree(amdi_ptr, AU_MALLOC_DBINFO_SZ);

        return (err);
}
#endif /* AUDIT_MALLOC_DEBUG */
        
/*
 * BSD malloc()
 * 
 * If the M_NOWAIT flag is set then it may not block and return NULL.
 * If the M_ZERO flag is set then zero out the buffer.
 */
void *
#if AUDIT_MALLOC_DEBUG
_audit_malloc(size_t size, au_malloc_type_t *type, int flags, const char *fn)
#else
_audit_malloc(size_t size, au_malloc_type_t *type, int flags)
#endif
{
        struct mhdr     *hdr;
        size_t  memsize;
        if (os_add_overflow(sizeof(*hdr), size, &memsize)) {
                return (NULL);
        }

        if (size == 0)
                return (NULL);
        if (flags & M_NOWAIT) {
                hdr = (void *)kalloc_noblock(memsize);
        } else {
                hdr = (void *)kalloc(memsize);
                if (hdr == NULL)
                        panic("_audit_malloc: kernel memory exhausted");
        }
        if (hdr == NULL)
                return (NULL);
        hdr->mh_size = memsize;
        hdr->mh_type = type;
        hdr->mh_magic = AUDIT_MHMAGIC;
        if (flags & M_ZERO)
                memset(hdr->mh_data, 0, size);
#if AUDIT_MALLOC_DEBUG
        if (type != NULL && type->mt_type < NUM_MALLOC_TYPES) {
                OSAddAtomic64(memsize, &type->mt_size);
                type->mt_maxsize = max(type->mt_size, type->mt_maxsize);
                OSAddAtomic(1, &type->mt_inuse);
                type->mt_maxused = max(type->mt_inuse, type->mt_maxused);
                type->mt_lastcaller = fn;
                audit_malloc_types[type->mt_type] = type;
        }
#endif /* AUDIT_MALLOC_DEBUG */
        return (hdr->mh_data);
}

/*
 * BSD free()
 */
void
#if AUDIT_MALLOC_DEBUG
_audit_free(void *addr, au_malloc_type_t *type)
#else
_audit_free(void *addr, __unused au_malloc_type_t *type)
#endif
{
        struct mhdr *hdr;
        
        if (addr == NULL)
                return;
        hdr = addr; hdr--;

        KASSERT(hdr->mh_magic == AUDIT_MHMAGIC,
            ("_audit_free(): hdr->mh_magic != AUDIT_MHMAGIC"));

#if AUDIT_MALLOC_DEBUG
        if (type != NULL) {
                OSAddAtomic64(-hdr->mh_size, &type->mt_size);
                OSAddAtomic(-1, &type->mt_inuse);
        }
#endif /* AUDIT_MALLOC_DEBUG */
        kfree(hdr, hdr->mh_size);
}

/*
 * Initialize a condition variable.  Must be called before use.
 */
void
_audit_cv_init(struct cv *cvp, const char *desc)
{

        if (desc == NULL)
                cvp->cv_description = "UNKNOWN";
        else
                cvp->cv_description = desc;
        cvp->cv_waiters = 0;
}

/*
 *  Destory a condition variable.
 */
void
_audit_cv_destroy(struct cv *cvp)
{

        cvp->cv_description = NULL;
        cvp->cv_waiters = 0;
}

/*
 * Signal a condition variable, wakes up one waiting thread.
 */
void
_audit_cv_signal(struct cv *cvp)
{

        if (cvp->cv_waiters > 0) {
                wakeup_one((caddr_t)cvp);
                cvp->cv_waiters--;
        }
}

/*
 * Broadcast a signal to a condition variable.
 */
void
_audit_cv_broadcast(struct cv *cvp)
{

        if (cvp->cv_waiters > 0) {
                wakeup((caddr_t)cvp);
                cvp->cv_waiters = 0;
        }
}

/*
 * Wait on a condition variable. A cv_signal or cv_broadcast on the same
 * condition variable will resume the thread. It is recommended that the mutex
 * be held when cv_signal or cv_broadcast are called.
 */
void
_audit_cv_wait(struct cv *cvp, lck_mtx_t *mp, const char *desc)
{

        cvp->cv_waiters++;
        (void) msleep(cvp, mp, PZERO, desc, 0);
}

/*
 * Wait on a condition variable, allowing interruption by signals.  Return 0
 * if the thread was resumed with cv_signal or cv_broadcast, EINTR or
 * ERESTART if a signal was caught.  If ERESTART is returned the system call
 * should be restarted if possible.
 */
int
_audit_cv_wait_sig(struct cv *cvp, lck_mtx_t *mp, const char *desc)
{

        cvp->cv_waiters++;
        return (msleep(cvp, mp, PSOCK | PCATCH, desc, 0));
}

/*
 * BSD Mutexes.
 */
void
#if DIAGNOSTIC
_audit_mtx_init(struct mtx *mp, const char *lckname)
#else
_audit_mtx_init(struct mtx *mp, __unused const char *lckname)
#endif
{
        mp->mtx_lock = lck_mtx_alloc_init(audit_lck_grp, LCK_ATTR_NULL);
        KASSERT(mp->mtx_lock != NULL, 
            ("_audit_mtx_init: Could not allocate a mutex."));
#if DIAGNOSTIC
        strlcpy(mp->mtx_name, lckname, AU_MAX_LCK_NAME);        
#endif
}

void
_audit_mtx_destroy(struct mtx *mp)
{

        if (mp->mtx_lock) {
                lck_mtx_free(mp->mtx_lock, audit_lck_grp);
                mp->mtx_lock = NULL;
        }
}

/*
 * BSD rw locks.
 */
void
#if DIAGNOSTIC
_audit_rw_init(struct rwlock *lp, const char *lckname)
#else
_audit_rw_init(struct rwlock *lp, __unused const char *lckname)
#endif
{
        lp->rw_lock = lck_rw_alloc_init(audit_lck_grp, LCK_ATTR_NULL);
        KASSERT(lp->rw_lock != NULL, 
            ("_audit_rw_init: Could not allocate a rw lock."));
#if DIAGNOSTIC
        strlcpy(lp->rw_name, lckname, AU_MAX_LCK_NAME); 
#endif
}

void
_audit_rw_destroy(struct rwlock *lp)
{

        if (lp->rw_lock) {
                lck_rw_free(lp->rw_lock, audit_lck_grp);
                lp->rw_lock = NULL;
        }
}
/*
 * Wait on a condition variable in a continuation (i.e. yield kernel stack).
 * A cv_signal or cv_broadcast on the same condition variable will cause
 * the thread to be scheduled.
 */
int
_audit_cv_wait_continuation(struct cv *cvp, lck_mtx_t *mp, thread_continue_t function)
{
        int status = KERN_SUCCESS;

        cvp->cv_waiters++;
        assert_wait(cvp, THREAD_UNINT);
        lck_mtx_unlock(mp);

        status = thread_block(function);

        /* should not be reached, but just in case, re-lock */
        lck_mtx_lock(mp);

        return status;
}

/*
 * Simple recursive lock. 
 */
void
#if DIAGNOSTIC
_audit_rlck_init(struct rlck *lp, const char *lckname)
#else
_audit_rlck_init(struct rlck *lp, __unused const char *lckname)
#endif
{

        lp->rl_mtx = lck_mtx_alloc_init(audit_lck_grp, LCK_ATTR_NULL);
        KASSERT(lp->rl_mtx != NULL, 
            ("_audit_rlck_init: Could not allocate a recursive lock."));
#if DIAGNOSTIC
        strlcpy(lp->rl_name, lckname, AU_MAX_LCK_NAME); 
#endif
        lp->rl_thread = 0;
        lp->rl_recurse = 0;
}

/*
 * Recursive lock.  Allow same thread to recursively lock the same lock.
 */ 
void
_audit_rlck_lock(struct rlck *lp)
{

        if (lp->rl_thread == current_thread()) {
                OSAddAtomic(1, &lp->rl_recurse);
                KASSERT(lp->rl_recurse < 10000,
                    ("_audit_rlck_lock: lock nested too deep."));
        } else {
                lck_mtx_lock(lp->rl_mtx);
                lp->rl_thread = current_thread();
                lp->rl_recurse = 1;
        }
}

/*
 * Recursive unlock.  It should be the same thread that does the unlock.
 */
void
_audit_rlck_unlock(struct rlck *lp)
{
        KASSERT(lp->rl_thread == current_thread(), 
            ("_audit_rlck_unlock(): Don't own lock."));

        /* Note: OSAddAtomic returns old value. */
        if (OSAddAtomic(-1, &lp->rl_recurse) == 1) {
                lp->rl_thread = 0;
                lck_mtx_unlock(lp->rl_mtx);
        }
}
                
void
_audit_rlck_destroy(struct rlck *lp)
{

        if (lp->rl_mtx) {
                lck_mtx_free(lp->rl_mtx, audit_lck_grp);
                lp->rl_mtx = NULL;
        }
}

/*
 * Recursive lock assert.
 */
void
_audit_rlck_assert(struct rlck *lp, u_int assert)
{
        thread_t cthd = current_thread();
        
        if (assert == LCK_MTX_ASSERT_OWNED && lp->rl_thread == cthd)
                panic("recursive lock (%p) not held by this thread (%p).",
                    lp, cthd);
        if (assert == LCK_MTX_ASSERT_NOTOWNED && lp->rl_thread != 0)
                panic("recursive lock (%p) held by thread (%p).",
                    lp, cthd);
}

/*
 * Simple sleep lock.
 */
void
#if DIAGNOSTIC
_audit_slck_init(struct slck *lp, const char *lckname)
#else
_audit_slck_init(struct slck *lp, __unused const char *lckname)
#endif
{

        lp->sl_mtx = lck_mtx_alloc_init(audit_lck_grp, LCK_ATTR_NULL);
        KASSERT(lp->sl_mtx != NULL, 
            ("_audit_slck_init: Could not allocate a sleep lock."));
#if DIAGNOSTIC
        strlcpy(lp->sl_name, lckname, AU_MAX_LCK_NAME); 
#endif
        lp->sl_locked = 0;
        lp->sl_waiting = 0;
}

/*
 * Sleep lock lock.  The 'intr' flag determines if the lock is interruptible.
 * If 'intr' is true then signals or other events can interrupt the sleep lock. 
 */
wait_result_t
_audit_slck_lock(struct slck *lp, int intr)
{
        wait_result_t res = THREAD_AWAKENED;

        lck_mtx_lock(lp->sl_mtx);
        while (lp->sl_locked && res == THREAD_AWAKENED) {
                lp->sl_waiting = 1;
                res = lck_mtx_sleep(lp->sl_mtx, LCK_SLEEP_DEFAULT,
                   (event_t) lp, (intr) ? THREAD_INTERRUPTIBLE : THREAD_UNINT);
        }
        if (res == THREAD_AWAKENED)
                lp->sl_locked = 1;
        lck_mtx_unlock(lp->sl_mtx);
        
        return (res);
}

/*
 * Sleep lock unlock.  Wake up all the threads waiting for this lock.
 */
void
_audit_slck_unlock(struct slck *lp)
{
        
        lck_mtx_lock(lp->sl_mtx);
        lp->sl_locked = 0;
        if (lp->sl_waiting) {
                lp->sl_waiting = 0;

                /* Wake up *all* sleeping threads. */
                wakeup((event_t) lp);
        }
        lck_mtx_unlock(lp->sl_mtx);
}

/*
 * Sleep lock try.  Don't sleep if it doesn't get the lock. 
 */
int
_audit_slck_trylock(struct slck *lp)
{
        int result;

        lck_mtx_lock(lp->sl_mtx);
        result = !lp->sl_locked;
        if (result)
                lp->sl_locked = 1;
        lck_mtx_unlock(lp->sl_mtx);

        return (result);
}

/*
 * Sleep lock assert.
 */
void
_audit_slck_assert(struct slck *lp, u_int assert)
{

        if (assert == LCK_MTX_ASSERT_OWNED && lp->sl_locked == 0)
                panic("sleep lock (%p) not held.", lp);
        if (assert == LCK_MTX_ASSERT_NOTOWNED && lp->sl_locked == 1)
                panic("sleep lock (%p) held.", lp);
}

void
_audit_slck_destroy(struct slck *lp)
{

        if (lp->sl_mtx) {
                lck_mtx_free(lp->sl_mtx, audit_lck_grp);
                lp->sl_mtx = NULL;
        }
}

/*
 * XXXss - This code was taken from bsd/netinet6/icmp6.c.  Maybe ppsratecheck()
 * should be made global in icmp6.c.
 */
#ifndef timersub
#define timersub(tvp, uvp, vvp)                                         \
        do {                                                            \
                (vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec;          \
                (vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec;       \
                if ((vvp)->tv_usec < 0) {                               \
                        (vvp)->tv_sec--;                                \
                        (vvp)->tv_usec += 1000000;                      \
                }                                                       \
        } while (0)
#endif

/*
 * Packets (or events) per second limitation.
 */
int
_audit_ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
{
        struct timeval tv, delta;
        int rv;

        microtime(&tv);

        timersub(&tv, lasttime, &delta);

        /*
         * Check for 0,0 so that the message will be seen at least once.
         * If more than one second has passed since the last update of
         * lasttime, reset the counter.
         *
         * we do increment *curpps even in *curpps < maxpps case, as some may
         * try to use *curpps for stat purposes as well.
         */
        if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
            delta.tv_sec >= 1) {
                *lasttime = tv;
                *curpps = 0;
                rv = 1;
        } else if (maxpps < 0)
                rv = 1;
        else if (*curpps < maxpps)
                rv = 1;
        else
                rv = 0;
        if (*curpps + 1 > 0)
                *curpps = *curpps + 1;

        return (rv);    
}

/*
 * Initialize lock group for audit related locks/mutexes.
 */
void
_audit_lck_grp_init(void)
{
        audit_lck_grp = lck_grp_alloc_init("Audit", LCK_GRP_ATTR_NULL);

        KASSERT(audit_lck_grp != NULL,
            ("audit_get_lck_grp: Could not allocate the audit lock group."));
}

int
audit_send_trigger(unsigned int trigger)
{
        mach_port_t audit_port;
        int error;

        error = host_get_audit_control_port(host_priv_self(), &audit_port);
        if (error == KERN_SUCCESS && audit_port != MACH_PORT_NULL) {
                (void)audit_triggers(audit_port, trigger);
                ipc_port_release_send(audit_port);
                return (0);
        } else {
                printf("Cannot get audit control port\n");
                return (error);
        }
}
#endif /* CONFIG_AUDIT */