xref: /freebsd/sys/security/audit/audit.c (revision da5432eda807c4b7232d030d5157d5b417ea4f52)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1999-2005 Apple Inc.
5  * Copyright (c) 2006-2007, 2016-2018 Robert N. M. Watson
6  * All rights reserved.
7  *
8  * Portions of this software were developed by BAE Systems, the University of
9  * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
10  * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
11  * Computing (TC) research program.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1.  Redistributions of source code must retain the above copyright
17  *     notice, this list of conditions and the following disclaimer.
18  * 2.  Redistributions in binary form must reproduce the above copyright
19  *     notice, this list of conditions and the following disclaimer in the
20  *     documentation and/or other materials provided with the distribution.
21  * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
22  *     its contributors may be used to endorse or promote products derived
23  *     from this software without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR
29  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
33  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
34  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35  * POSSIBILITY OF SUCH DAMAGE.
36  */
37 
38 #include <sys/cdefs.h>
39 #include <sys/param.h>
40 #include <sys/condvar.h>
41 #include <sys/conf.h>
42 #include <sys/eventhandler.h>
43 #include <sys/file.h>
44 #include <sys/filedesc.h>
45 #include <sys/fcntl.h>
46 #include <sys/ipc.h>
47 #include <sys/jail.h>
48 #include <sys/kernel.h>
49 #include <sys/kthread.h>
50 #include <sys/malloc.h>
51 #include <sys/mount.h>
52 #include <sys/namei.h>
53 #include <sys/priv.h>
54 #include <sys/proc.h>
55 #include <sys/queue.h>
56 #include <sys/socket.h>
57 #include <sys/socketvar.h>
58 #include <sys/protosw.h>
59 #include <sys/domain.h>
60 #include <sys/sysctl.h>
61 #include <sys/sysproto.h>
62 #include <sys/sysent.h>
63 #include <sys/systm.h>
64 #include <sys/ucred.h>
65 #include <sys/uio.h>
66 #include <sys/un.h>
67 #include <sys/unistd.h>
68 #include <sys/vnode.h>
69 
70 #include <bsm/audit.h>
71 #include <bsm/audit_internal.h>
72 #include <bsm/audit_kevents.h>
73 
74 #include <netinet/in.h>
75 #include <netinet/in_pcb.h>
76 
77 #include <security/audit/audit.h>
78 #include <security/audit/audit_private.h>
79 
80 #include <vm/uma.h>
81 
82 FEATURE(audit, "BSM audit support");
83 
84 static uma_zone_t	audit_record_zone;
85 static MALLOC_DEFINE(M_AUDITCRED, "audit_cred", "Audit cred storage");
86 MALLOC_DEFINE(M_AUDITDATA, "audit_data", "Audit data storage");
87 MALLOC_DEFINE(M_AUDITPATH, "audit_path", "Audit path storage");
88 MALLOC_DEFINE(M_AUDITTEXT, "audit_text", "Audit text storage");
89 MALLOC_DEFINE(M_AUDITGIDSET, "audit_gidset", "Audit GID set storage");
90 
91 static SYSCTL_NODE(_security, OID_AUTO, audit, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
92     "TrustedBSD audit controls");
93 
94 /*
95  * Audit control settings that are set/read by system calls and are hence
96  * non-static.
97  *
98  * Define the audit control flags.
99  */
100 int			audit_trail_enabled;
101 int			audit_trail_suspended;
102 #ifdef KDTRACE_HOOKS
103 u_int			audit_dtrace_enabled;
104 #endif
105 bool __read_frequently	audit_syscalls_enabled;
106 
107 /*
108  * Flags controlling behavior in low storage situations.  Should we panic if
109  * a write fails?  Should we fail stop if we're out of disk space?
110  */
111 int			audit_panic_on_write_fail;
112 int			audit_fail_stop;
113 int			audit_argv;
114 int			audit_arge;
115 
116 /*
117  * Are we currently "failing stop" due to out of disk space?
118  */
119 int			audit_in_failure;
120 
121 /*
122  * Global audit statistics.
123  */
124 struct audit_fstat	audit_fstat;
125 
126 /*
127  * Preselection mask for non-attributable events.
128  */
129 struct au_mask		audit_nae_mask;
130 
131 /*
132  * Mutex to protect global variables shared between various threads and
133  * processes.
134  */
135 struct mtx		audit_mtx;
136 
137 /*
138  * Queue of audit records ready for delivery to disk.  We insert new records
139  * at the tail, and remove records from the head.  Also, a count of the
140  * number of records used for checking queue depth.  In addition, a counter
141  * of records that we have allocated but are not yet in the queue, which is
142  * needed to estimate the total size of the combined set of records
143  * outstanding in the system.
144  */
145 struct kaudit_queue	audit_q;
146 int			audit_q_len;
147 int			audit_pre_q_len;
148 
149 /*
150  * Audit queue control settings (minimum free, low/high water marks, etc.)
151  */
152 struct au_qctrl		audit_qctrl;
153 
154 /*
155  * Condition variable to signal to the worker that it has work to do: either
156  * new records are in the queue, or a log replacement is taking place.
157  */
158 struct cv		audit_worker_cv;
159 
160 /*
161  * Condition variable to flag when crossing the low watermark, meaning that
162  * threads blocked due to hitting the high watermark can wake up and continue
163  * to commit records.
164  */
165 struct cv		audit_watermark_cv;
166 
167 /*
168  * Condition variable for  auditing threads wait on when in fail-stop mode.
169  * Threads wait on this CV forever (and ever), never seeing the light of day
170  * again.
171  */
172 static struct cv	audit_fail_cv;
173 
174 /*
175  * Optional DTrace audit provider support: function pointers for preselection
176  * and commit events.
177  */
178 #ifdef KDTRACE_HOOKS
179 void	*(*dtaudit_hook_preselect)(au_id_t auid, au_event_t event,
180 	    au_class_t class);
181 int	(*dtaudit_hook_commit)(struct kaudit_record *kar, au_id_t auid,
182 	    au_event_t event, au_class_t class, int sorf);
183 void	(*dtaudit_hook_bsm)(struct kaudit_record *kar, au_id_t auid,
184 	    au_event_t event, au_class_t class, int sorf,
185 	    void *bsm_data, size_t bsm_lenlen);
186 #endif
187 
188 /*
189  * Kernel audit information.  This will store the current audit address
190  * or host information that the kernel will use when it's generating
191  * audit records.  This data is modified by the A_GET{SET}KAUDIT auditon(2)
192  * command.
193  */
194 static struct auditinfo_addr	audit_kinfo;
195 static struct rwlock		audit_kinfo_lock;
196 
197 #define	KINFO_LOCK_INIT()	rw_init(&audit_kinfo_lock, \
198 				    "audit_kinfo_lock")
199 #define	KINFO_RLOCK()		rw_rlock(&audit_kinfo_lock)
200 #define	KINFO_WLOCK()		rw_wlock(&audit_kinfo_lock)
201 #define	KINFO_RUNLOCK()		rw_runlock(&audit_kinfo_lock)
202 #define	KINFO_WUNLOCK()		rw_wunlock(&audit_kinfo_lock)
203 
204 /*
205  * Check various policies to see if we should enable system-call audit hooks.
206  * Note that despite the mutex being held, we want to assign a value exactly
207  * once, as checks of the flag are performed lock-free for performance
208  * reasons.  The mutex is used to get a consistent snapshot of policy state --
209  * e.g., safely accessing the two audit_trail flags.
210  */
211 void
212 audit_syscalls_enabled_update(void)
213 {
214 
215 	mtx_lock(&audit_mtx);
216 #ifdef KDTRACE_HOOKS
217 	if (audit_dtrace_enabled)
218 		audit_syscalls_enabled = true;
219 	else {
220 #endif
221 		if (audit_trail_enabled && !audit_trail_suspended)
222 			audit_syscalls_enabled = true;
223 		else
224 			audit_syscalls_enabled = false;
225 #ifdef KDTRACE_HOOKS
226 	}
227 #endif
228 	mtx_unlock(&audit_mtx);
229 }
230 
231 void
232 audit_set_kinfo(struct auditinfo_addr *ak)
233 {
234 
235 	KASSERT(ak->ai_termid.at_type == AU_IPv4 ||
236 	    ak->ai_termid.at_type == AU_IPv6,
237 	    ("audit_set_kinfo: invalid address type"));
238 
239 	KINFO_WLOCK();
240 	audit_kinfo = *ak;
241 	KINFO_WUNLOCK();
242 }
243 
244 void
245 audit_get_kinfo(struct auditinfo_addr *ak)
246 {
247 
248 	KASSERT(audit_kinfo.ai_termid.at_type == AU_IPv4 ||
249 	    audit_kinfo.ai_termid.at_type == AU_IPv6,
250 	    ("audit_set_kinfo: invalid address type"));
251 
252 	KINFO_RLOCK();
253 	*ak = audit_kinfo;
254 	KINFO_RUNLOCK();
255 }
256 
257 /*
258  * Construct an audit record for the passed thread.
259  */
260 static int
261 audit_record_ctor(void *mem, int size, void *arg, int flags)
262 {
263 	struct kaudit_record *ar;
264 	struct thread *td;
265 	struct ucred *cred;
266 	struct prison *pr;
267 
268 	KASSERT(sizeof(*ar) == size, ("audit_record_ctor: wrong size"));
269 
270 	td = arg;
271 	ar = mem;
272 	bzero(ar, sizeof(*ar));
273 	ar->k_ar.ar_magic = AUDIT_RECORD_MAGIC;
274 	nanotime(&ar->k_ar.ar_starttime);
275 
276 	/*
277 	 * Export the subject credential.
278 	 */
279 	cred = td->td_ucred;
280 	cru2x(cred, &ar->k_ar.ar_subj_cred);
281 	ar->k_ar.ar_subj_ruid = cred->cr_ruid;
282 	ar->k_ar.ar_subj_rgid = cred->cr_rgid;
283 	ar->k_ar.ar_subj_egid = cred->cr_groups[0];
284 	ar->k_ar.ar_subj_auid = cred->cr_audit.ai_auid;
285 	ar->k_ar.ar_subj_asid = cred->cr_audit.ai_asid;
286 	ar->k_ar.ar_subj_pid = td->td_proc->p_pid;
287 	ar->k_ar.ar_subj_amask = cred->cr_audit.ai_mask;
288 	ar->k_ar.ar_subj_term_addr = cred->cr_audit.ai_termid;
289 	/*
290 	 * If this process is jailed, make sure we capture the name of the
291 	 * jail so we can use it to generate a zonename token when we covert
292 	 * this record to BSM.
293 	 */
294 	if (jailed(cred)) {
295 		pr = cred->cr_prison;
296 		(void) strlcpy(ar->k_ar.ar_jailname, pr->pr_name,
297 		    sizeof(ar->k_ar.ar_jailname));
298 	} else
299 		ar->k_ar.ar_jailname[0] = '\0';
300 	return (0);
301 }
302 
303 static void
304 audit_record_dtor(void *mem, int size, void *arg)
305 {
306 	struct kaudit_record *ar;
307 
308 	KASSERT(sizeof(*ar) == size, ("audit_record_dtor: wrong size"));
309 
310 	ar = mem;
311 	if (ar->k_ar.ar_arg_upath1 != NULL)
312 		free(ar->k_ar.ar_arg_upath1, M_AUDITPATH);
313 	if (ar->k_ar.ar_arg_upath2 != NULL)
314 		free(ar->k_ar.ar_arg_upath2, M_AUDITPATH);
315 	if (ar->k_ar.ar_arg_text != NULL)
316 		free(ar->k_ar.ar_arg_text, M_AUDITTEXT);
317 	if (ar->k_udata != NULL)
318 		free(ar->k_udata, M_AUDITDATA);
319 	if (ar->k_ar.ar_arg_argv != NULL)
320 		free(ar->k_ar.ar_arg_argv, M_AUDITTEXT);
321 	if (ar->k_ar.ar_arg_envv != NULL)
322 		free(ar->k_ar.ar_arg_envv, M_AUDITTEXT);
323 	if (ar->k_ar.ar_arg_groups.gidset != NULL)
324 		free(ar->k_ar.ar_arg_groups.gidset, M_AUDITGIDSET);
325 }
326 
327 /*
328  * Initialize the Audit subsystem: configuration state, work queue,
329  * synchronization primitives, worker thread, and trigger device node.  Also
330  * call into the BSM assembly code to initialize it.
331  */
332 static void
333 audit_init(void)
334 {
335 
336 	audit_trail_enabled = 0;
337 	audit_trail_suspended = 0;
338 	audit_syscalls_enabled = false;
339 	audit_panic_on_write_fail = 0;
340 	audit_fail_stop = 0;
341 	audit_in_failure = 0;
342 	audit_argv = 0;
343 	audit_arge = 0;
344 
345 	audit_fstat.af_filesz = 0;	/* '0' means unset, unbounded. */
346 	audit_fstat.af_currsz = 0;
347 	audit_nae_mask.am_success = 0;
348 	audit_nae_mask.am_failure = 0;
349 
350 	TAILQ_INIT(&audit_q);
351 	audit_q_len = 0;
352 	audit_pre_q_len = 0;
353 	audit_qctrl.aq_hiwater = AQ_HIWATER;
354 	audit_qctrl.aq_lowater = AQ_LOWATER;
355 	audit_qctrl.aq_bufsz = AQ_BUFSZ;
356 	audit_qctrl.aq_minfree = AU_FS_MINFREE;
357 
358 	audit_kinfo.ai_termid.at_type = AU_IPv4;
359 	audit_kinfo.ai_termid.at_addr[0] = INADDR_ANY;
360 
361 	mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF);
362 	KINFO_LOCK_INIT();
363 	cv_init(&audit_worker_cv, "audit_worker_cv");
364 	cv_init(&audit_watermark_cv, "audit_watermark_cv");
365 	cv_init(&audit_fail_cv, "audit_fail_cv");
366 
367 	audit_record_zone = uma_zcreate("audit_record",
368 	    sizeof(struct kaudit_record), audit_record_ctor,
369 	    audit_record_dtor, NULL, NULL, UMA_ALIGN_PTR, 0);
370 
371 	/* First initialisation of audit_syscalls_enabled. */
372 	audit_syscalls_enabled_update();
373 
374 	/* Initialize the BSM audit subsystem. */
375 	kau_init();
376 
377 	audit_trigger_init();
378 
379 	/* Register shutdown handler. */
380 	EVENTHANDLER_REGISTER(shutdown_pre_sync, audit_shutdown, NULL,
381 	    SHUTDOWN_PRI_FIRST);
382 
383 	/* Start audit worker thread. */
384 	audit_worker_init();
385 }
386 
387 SYSINIT(audit_init, SI_SUB_AUDIT, SI_ORDER_FIRST, audit_init, NULL);
388 
389 /*
390  * Drain the audit queue and close the log at shutdown.  Note that this can
391  * be called both from the system shutdown path and also from audit
392  * configuration syscalls, so 'arg' and 'howto' are ignored.
393  *
394  * XXXRW: In FreeBSD 7.x and 8.x, this fails to wait for the record queue to
395  * drain before returning, which could lead to lost records on shutdown.
396  */
397 void
398 audit_shutdown(void *arg, int howto)
399 {
400 
401 	audit_rotate_vnode(NULL, NULL);
402 }
403 
404 /*
405  * Return the current thread's audit record, if any.
406  */
407 struct kaudit_record *
408 currecord(void)
409 {
410 
411 	return (curthread->td_ar);
412 }
413 
414 /*
415  * XXXAUDIT: Shouldn't there be logic here to sleep waiting on available
416  * pre_q space, suspending the system call until there is room?
417  */
418 struct kaudit_record *
419 audit_new(int event, struct thread *td)
420 {
421 	struct kaudit_record *ar;
422 
423 	/*
424 	 * Note: the number of outstanding uncommitted audit records is
425 	 * limited to the number of concurrent threads servicing system calls
426 	 * in the kernel.
427 	 */
428 	ar = uma_zalloc_arg(audit_record_zone, td, M_WAITOK);
429 	ar->k_ar.ar_event = event;
430 
431 	mtx_lock(&audit_mtx);
432 	audit_pre_q_len++;
433 	mtx_unlock(&audit_mtx);
434 
435 	return (ar);
436 }
437 
438 void
439 audit_free(struct kaudit_record *ar)
440 {
441 
442 	uma_zfree(audit_record_zone, ar);
443 }
444 
445 void
446 audit_commit(struct kaudit_record *ar, int error, int retval)
447 {
448 	au_event_t event;
449 	au_class_t class;
450 	au_id_t auid;
451 	int sorf;
452 	struct au_mask *aumask;
453 
454 	if (ar == NULL)
455 		return;
456 
457 	ar->k_ar.ar_errno = error;
458 	ar->k_ar.ar_retval = retval;
459 	nanotime(&ar->k_ar.ar_endtime);
460 
461 	/*
462 	 * Decide whether to commit the audit record by checking the error
463 	 * value from the system call and using the appropriate audit mask.
464 	 */
465 	if (ar->k_ar.ar_subj_auid == AU_DEFAUDITID)
466 		aumask = &audit_nae_mask;
467 	else
468 		aumask = &ar->k_ar.ar_subj_amask;
469 
470 	if (error)
471 		sorf = AU_PRS_FAILURE;
472 	else
473 		sorf = AU_PRS_SUCCESS;
474 
475 	/*
476 	 * syscalls.master sometimes contains a prototype event number, which
477 	 * we will transform into a more specific event number now that we
478 	 * have more complete information gathered during the system call.
479 	 */
480 	switch(ar->k_ar.ar_event) {
481 	case AUE_OPEN_RWTC:
482 		ar->k_ar.ar_event = audit_flags_and_error_to_openevent(
483 		    ar->k_ar.ar_arg_fflags, error);
484 		break;
485 
486 	case AUE_OPENAT_RWTC:
487 		ar->k_ar.ar_event = audit_flags_and_error_to_openatevent(
488 		    ar->k_ar.ar_arg_fflags, error);
489 		break;
490 
491 	case AUE_SYSCTL:
492 		ar->k_ar.ar_event = audit_ctlname_to_sysctlevent(
493 		    ar->k_ar.ar_arg_ctlname, ar->k_ar.ar_valid_arg);
494 		break;
495 
496 	case AUE_AUDITON:
497 		/* Convert the auditon() command to an event. */
498 		ar->k_ar.ar_event = auditon_command_event(ar->k_ar.ar_arg_cmd);
499 		break;
500 
501 	case AUE_MSGSYS:
502 		if (ARG_IS_VALID(ar, ARG_SVIPC_WHICH))
503 			ar->k_ar.ar_event =
504 			    audit_msgsys_to_event(ar->k_ar.ar_arg_svipc_which);
505 		break;
506 
507 	case AUE_SEMSYS:
508 		if (ARG_IS_VALID(ar, ARG_SVIPC_WHICH))
509 			ar->k_ar.ar_event =
510 			    audit_semsys_to_event(ar->k_ar.ar_arg_svipc_which);
511 		break;
512 
513 	case AUE_SHMSYS:
514 		if (ARG_IS_VALID(ar, ARG_SVIPC_WHICH))
515 			ar->k_ar.ar_event =
516 			    audit_shmsys_to_event(ar->k_ar.ar_arg_svipc_which);
517 		break;
518 	}
519 
520 	auid = ar->k_ar.ar_subj_auid;
521 	event = ar->k_ar.ar_event;
522 	class = au_event_class(event);
523 
524 	ar->k_ar_commit |= AR_COMMIT_KERNEL;
525 	if (au_preselect(event, class, aumask, sorf) != 0)
526 		ar->k_ar_commit |= AR_PRESELECT_TRAIL;
527 	if (audit_pipe_preselect(auid, event, class, sorf,
528 	    ar->k_ar_commit & AR_PRESELECT_TRAIL) != 0)
529 		ar->k_ar_commit |= AR_PRESELECT_PIPE;
530 #ifdef KDTRACE_HOOKS
531 	/*
532 	 * Expose the audit record to DTrace, both to allow the "commit" probe
533 	 * to fire if it's desirable, and also to allow a decision to be made
534 	 * about later firing with BSM in the audit worker.
535 	 */
536 	if (dtaudit_hook_commit != NULL) {
537 		if (dtaudit_hook_commit(ar, auid, event, class, sorf) != 0)
538 			ar->k_ar_commit |= AR_PRESELECT_DTRACE;
539 	}
540 #endif
541 
542 	if ((ar->k_ar_commit & (AR_PRESELECT_TRAIL | AR_PRESELECT_PIPE |
543 	    AR_PRESELECT_USER_TRAIL | AR_PRESELECT_USER_PIPE |
544 	    AR_PRESELECT_DTRACE)) == 0) {
545 		mtx_lock(&audit_mtx);
546 		audit_pre_q_len--;
547 		mtx_unlock(&audit_mtx);
548 		audit_free(ar);
549 		return;
550 	}
551 
552 	/*
553 	 * Note: it could be that some records initiated while audit was
554 	 * enabled should still be committed?
555 	 *
556 	 * NB: The check here is not for audit_syscalls because any
557 	 * DTrace-related obligations have been fulfilled above -- we're just
558 	 * down to the trail and pipes now.
559 	 */
560 	mtx_lock(&audit_mtx);
561 	if (audit_trail_suspended || !audit_trail_enabled) {
562 		audit_pre_q_len--;
563 		mtx_unlock(&audit_mtx);
564 		audit_free(ar);
565 		return;
566 	}
567 
568 	/*
569 	 * Constrain the number of committed audit records based on the
570 	 * configurable parameter.
571 	 */
572 	while (audit_q_len >= audit_qctrl.aq_hiwater)
573 		cv_wait(&audit_watermark_cv, &audit_mtx);
574 
575 	TAILQ_INSERT_TAIL(&audit_q, ar, k_q);
576 	audit_q_len++;
577 	audit_pre_q_len--;
578 	cv_signal(&audit_worker_cv);
579 	mtx_unlock(&audit_mtx);
580 }
581 
582 /*
583  * audit_syscall_enter() is called on entry to each system call.  It is
584  * responsible for deciding whether or not to audit the call (preselection),
585  * and if so, allocating a per-thread audit record.  audit_new() will fill in
586  * basic thread/credential properties.
587  *
588  * This function will be entered only if audit_syscalls_enabled was set in the
589  * macro wrapper for this function.  It could be cleared by the time this
590  * function runs, but that is an acceptable race.
591  */
592 void
593 audit_syscall_enter(unsigned short code, struct thread *td)
594 {
595 	struct au_mask *aumask;
596 #ifdef KDTRACE_HOOKS
597 	void *dtaudit_state;
598 #endif
599 	au_class_t class;
600 	au_event_t event;
601 	au_id_t auid;
602 	int record_needed;
603 
604 	KASSERT(td->td_ar == NULL, ("audit_syscall_enter: td->td_ar != NULL"));
605 	KASSERT((td->td_pflags & TDP_AUDITREC) == 0,
606 	    ("audit_syscall_enter: TDP_AUDITREC set"));
607 
608 	/*
609 	 * In FreeBSD, each ABI has its own system call table, and hence
610 	 * mapping of system call codes to audit events.  Convert the code to
611 	 * an audit event identifier using the process system call table
612 	 * reference.  In Darwin, there's only one, so we use the global
613 	 * symbol for the system call table.  No audit record is generated
614 	 * for bad system calls, as no operation has been performed.
615 	 */
616 	if (code >= td->td_proc->p_sysent->sv_size)
617 		return;
618 
619 	event = td->td_proc->p_sysent->sv_table[code].sy_auevent;
620 	if (event == AUE_NULL)
621 		return;
622 
623 	/*
624 	 * Check which audit mask to use; either the kernel non-attributable
625 	 * event mask or the process audit mask.
626 	 */
627 	auid = td->td_ucred->cr_audit.ai_auid;
628 	if (auid == AU_DEFAUDITID)
629 		aumask = &audit_nae_mask;
630 	else
631 		aumask = &td->td_ucred->cr_audit.ai_mask;
632 
633 	/*
634 	 * Determine whether trail or pipe preselection would like an audit
635 	 * record allocated for this system call.
636 	 */
637 	class = au_event_class(event);
638 	if (au_preselect(event, class, aumask, AU_PRS_BOTH)) {
639 		/*
640 		 * If we're out of space and need to suspend unprivileged
641 		 * processes, do that here rather than trying to allocate
642 		 * another audit record.
643 		 *
644 		 * Note: we might wish to be able to continue here in the
645 		 * future, if the system recovers.  That should be possible
646 		 * by means of checking the condition in a loop around
647 		 * cv_wait().  It might be desirable to reevaluate whether an
648 		 * audit record is still required for this event by
649 		 * re-calling au_preselect().
650 		 */
651 		if (audit_in_failure &&
652 		    priv_check(td, PRIV_AUDIT_FAILSTOP) != 0) {
653 			cv_wait(&audit_fail_cv, &audit_mtx);
654 			panic("audit_failing_stop: thread continued");
655 		}
656 		record_needed = 1;
657 	} else if (audit_pipe_preselect(auid, event, class, AU_PRS_BOTH, 0)) {
658 		record_needed = 1;
659 	} else {
660 		record_needed = 0;
661 	}
662 
663 	/*
664 	 * After audit trails and pipes have made their policy choices, DTrace
665 	 * may request that records be generated as well.  This is a slightly
666 	 * complex affair, as the DTrace audit provider needs the audit
667 	 * framework to maintain some state on the audit record, which has not
668 	 * been allocated at the point where the decision has to be made.
669 	 * This hook must run even if we are not changing the decision, as
670 	 * DTrace may want to stick event state onto a record we were going to
671 	 * produce due to the trail or pipes.  The event state returned by the
672 	 * DTrace provider must be safe without locks held between here and
673 	 * below -- i.e., dtaudit_state must must refer to stable memory.
674 	 */
675 #ifdef KDTRACE_HOOKS
676 	dtaudit_state = NULL;
677         if (dtaudit_hook_preselect != NULL) {
678 		dtaudit_state = dtaudit_hook_preselect(auid, event, class);
679 		if (dtaudit_state != NULL)
680 			record_needed = 1;
681 	}
682 #endif
683 
684 	/*
685 	 * If a record is required, allocate it and attach it to the thread
686 	 * for use throughout the system call.  Also attach DTrace state if
687 	 * required.
688 	 *
689 	 * XXXRW: If we decide to reference count the evname_elem underlying
690 	 * dtaudit_state, we will need to free here if no record is allocated
691 	 * or allocatable.
692 	 */
693 	if (record_needed) {
694 		td->td_ar = audit_new(event, td);
695 		if (td->td_ar != NULL) {
696 			td->td_pflags |= TDP_AUDITREC;
697 #ifdef KDTRACE_HOOKS
698 			td->td_ar->k_dtaudit_state = dtaudit_state;
699 #endif
700 		}
701 	} else
702 		td->td_ar = NULL;
703 }
704 
705 /*
706  * audit_syscall_exit() is called from the return of every system call, or in
707  * the event of exit1(), during the execution of exit1().  It is responsible
708  * for committing the audit record, if any, along with return condition.
709  */
710 void
711 audit_syscall_exit(int error, struct thread *td)
712 {
713 	int retval;
714 
715 	/*
716 	 * Commit the audit record as desired; once we pass the record into
717 	 * audit_commit(), the memory is owned by the audit subsystem.  The
718 	 * return value from the system call is stored on the user thread.
719 	 * If there was an error, the return value is set to -1, imitating
720 	 * the behavior of the cerror routine.
721 	 */
722 	if (error)
723 		retval = -1;
724 	else
725 		retval = td->td_retval[0];
726 
727 	audit_commit(td->td_ar, error, retval);
728 	td->td_ar = NULL;
729 	td->td_pflags &= ~TDP_AUDITREC;
730 }
731 
732 void
733 audit_cred_copy(struct ucred *src, struct ucred *dest)
734 {
735 
736 	bcopy(&src->cr_audit, &dest->cr_audit, sizeof(dest->cr_audit));
737 }
738 
739 void
740 audit_cred_destroy(struct ucred *cred)
741 {
742 
743 }
744 
745 void
746 audit_cred_init(struct ucred *cred)
747 {
748 
749 	bzero(&cred->cr_audit, sizeof(cred->cr_audit));
750 }
751 
752 /*
753  * Initialize audit information for the first kernel process (proc 0) and for
754  * the first user process (init).
755  */
756 void
757 audit_cred_kproc0(struct ucred *cred)
758 {
759 
760 	cred->cr_audit.ai_auid = AU_DEFAUDITID;
761 	cred->cr_audit.ai_termid.at_type = AU_IPv4;
762 }
763 
764 void
765 audit_cred_proc1(struct ucred *cred)
766 {
767 
768 	cred->cr_audit.ai_auid = AU_DEFAUDITID;
769 	cred->cr_audit.ai_termid.at_type = AU_IPv4;
770 }
771 
772 void
773 audit_thread_alloc(struct thread *td)
774 {
775 
776 	td->td_ar = NULL;
777 }
778 
779 void
780 audit_thread_free(struct thread *td)
781 {
782 
783 	KASSERT(td->td_ar == NULL, ("audit_thread_free: td_ar != NULL"));
784 	KASSERT((td->td_pflags & TDP_AUDITREC) == 0,
785 	    ("audit_thread_free: TDP_AUDITREC set"));
786 }
787 
788 void
789 audit_proc_coredump(struct thread *td, char *path, int errcode)
790 {
791 	struct kaudit_record *ar;
792 	struct au_mask *aumask;
793 	struct ucred *cred;
794 	au_class_t class;
795 	int ret, sorf;
796 	char **pathp;
797 	au_id_t auid;
798 
799 	ret = 0;
800 
801 	/*
802 	 * Make sure we are using the correct preselection mask.
803 	 */
804 	cred = td->td_ucred;
805 	auid = cred->cr_audit.ai_auid;
806 	if (auid == AU_DEFAUDITID)
807 		aumask = &audit_nae_mask;
808 	else
809 		aumask = &cred->cr_audit.ai_mask;
810 	/*
811 	 * It's possible for coredump(9) generation to fail.  Make sure that
812 	 * we handle this case correctly for preselection.
813 	 */
814 	if (errcode != 0)
815 		sorf = AU_PRS_FAILURE;
816 	else
817 		sorf = AU_PRS_SUCCESS;
818 	class = au_event_class(AUE_CORE);
819 	if (au_preselect(AUE_CORE, class, aumask, sorf) == 0 &&
820 	    audit_pipe_preselect(auid, AUE_CORE, class, sorf, 0) == 0)
821 		return;
822 
823 	/*
824 	 * If we are interested in seeing this audit record, allocate it.
825 	 * Where possible coredump records should contain a pathname and arg32
826 	 * (signal) tokens.
827 	 */
828 	ar = audit_new(AUE_CORE, td);
829 	if (ar == NULL)
830 		return;
831 	if (path != NULL) {
832 		pathp = &ar->k_ar.ar_arg_upath1;
833 		*pathp = malloc(MAXPATHLEN, M_AUDITPATH, M_WAITOK);
834 		audit_canon_path(td, AT_FDCWD, path, *pathp);
835 		ARG_SET_VALID(ar, ARG_UPATH1);
836 	}
837 	ar->k_ar.ar_arg_signum = td->td_proc->p_sig;
838 	ARG_SET_VALID(ar, ARG_SIGNUM);
839 	if (errcode != 0)
840 		ret = 1;
841 	audit_commit(ar, errcode, ret);
842 }
843