audit_bsd.c   [plain text]

/*-
 * Copyright (c) 2008-2009 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>

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

#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
{
	union {
	    struct mhdr	hdr;
	    char mem[size + sizeof (struct mhdr)];
	} *mem;
	size_t	memsize = sizeof (*mem);

	if (size == 0)
		return (NULL);
	if (flags & M_NOWAIT) {
		mem = (void *)kalloc_noblock(memsize);
	} else {
		mem = (void *)kalloc(memsize);
		if (mem == NULL)
			panic("_audit_malloc: kernel memory exhausted");
	}
	if (mem == NULL)
		return (NULL);
	mem->hdr.mh_size = memsize;
	mem->hdr.mh_type = type;
	mem->hdr.mh_magic = AUDIT_MHMAGIC;
	if (flags & M_ZERO)
		memset(mem->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 (mem->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));
}

/*
 * Simple recursive lock. 
 */
void
_audit_rlck_init(struct rlck *lp, const char *grpname)
{

	lp->rl_grp = lck_grp_alloc_init(grpname, LCK_GRP_ATTR_NULL);
	lp->rl_mtx = lck_mtx_alloc_init(lp->rl_grp, LCK_ATTR_NULL);

	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, lp->rl_grp);
		lp->rl_mtx = 0;
	}
	if (lp->rl_grp) {
		lck_grp_free(lp->rl_grp);
		lp->rl_grp = 0;
	}
}

/*
 * 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
_audit_slck_init(struct slck *lp, const char *grpname)
{

	lp->sl_grp = lck_grp_alloc_init(grpname, LCK_GRP_ATTR_NULL);
	lp->sl_mtx = lck_mtx_alloc_init(lp->sl_grp, LCK_ATTR_NULL);

	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. */
		thread_wakeup_prim((event_t) lp, /*1 thr*/ 0, THREAD_AWAKENED);
	}
	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, lp->sl_grp);
		lp->sl_mtx = 0;
	}
	if (lp->sl_grp) {
		lck_grp_free(lp->sl_grp);
		lp->sl_grp = 0;
	}
}

/*
 * 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);	
}

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) {
		audit_triggers(audit_port, trigger);
		return (0);
	} else {
		printf("Cannot get audit control port\n");
		return (error);
	}
}
#endif /* CONFIG_AUDIT */