1/*
2 * Copyright (c) 1999-2005 Apple Computer, Inc.
3 * Copyright (c) 2006 Robert N. M. Watson
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
15 * its contributors may be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR
22 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
27 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 *
30 * $FreeBSD: head/sys/security/audit/audit.c 159261 2006-06-05 13:43:57Z rwatson $
31 */
32
33#include <sys/param.h>
34#include <sys/condvar.h>
35#include <sys/conf.h>
36#include <sys/file.h>
37#include <sys/filedesc.h>
38#include <sys/fcntl.h>
39#include <sys/ipc.h>
40#include <sys/kernel.h>
41#include <sys/kthread.h>
42#include <sys/malloc.h>
43#include <sys/mount.h>
44#include <sys/namei.h>
45#include <sys/proc.h>
46#include <sys/queue.h>
47#include <sys/socket.h>
48#include <sys/socketvar.h>
49#include <sys/protosw.h>
50#include <sys/domain.h>
51#include <sys/sysproto.h>
52#include <sys/sysent.h>
53#include <sys/systm.h>
54#include <sys/ucred.h>
55#include <sys/uio.h>
56#include <sys/un.h>
57#include <sys/unistd.h>
58#include <sys/vnode.h>
59
60#include <bsm/audit.h>
61#include <bsm/audit_internal.h>
62#include <bsm/audit_kevents.h>
63
64#include <netinet/in.h>
65#include <netinet/in_pcb.h>
66
67#include <security/audit/audit.h>
68#include <security/audit/audit_private.h>
69
70#include <vm/uma.h>
71
72static uma_zone_t audit_record_zone;
73static MALLOC_DEFINE(M_AUDITPROC, "audit_proc", "Audit process storage");
74MALLOC_DEFINE(M_AUDITDATA, "audit_data", "Audit data storage");
75MALLOC_DEFINE(M_AUDITPATH, "audit_path", "Audit path storage");
76MALLOC_DEFINE(M_AUDITTEXT, "audit_text", "Audit text storage");
77
78/*
79 * Audit control settings that are set/read by system calls and are
80 * hence non-static.
81 */
82/*
83 * Define the audit control flags.
84 */
85int audit_enabled;
86int audit_suspended;
87
88/*
89 * Flags controlling behavior in low storage situations.
90 * Should we panic if a write fails? Should we fail stop
91 * if we're out of disk space?
92 */
93int audit_panic_on_write_fail;
94int audit_fail_stop;
95
96/*
97 * Are we currently "failing stop" due to out of disk space?
98 */
99int audit_in_failure;
100
101/*
102 * Global audit statistiscs.
103 */
104struct audit_fstat audit_fstat;
105
106/*
107 * Preselection mask for non-attributable events.
108 */
109struct au_mask audit_nae_mask;
110
111/*
112 * Mutex to protect global variables shared between various threads and
113 * processes.
114 */
115struct mtx audit_mtx;
116
117/*
118 * Queue of audit records ready for delivery to disk. We insert new
119 * records at the tail, and remove records from the head. Also,
120 * a count of the number of records used for checking queue depth.
121 * In addition, a counter of records that we have allocated but are
122 * not yet in the queue, which is needed to estimate the total
123 * size of the combined set of records outstanding in the system.
124 */
125struct kaudit_queue audit_q;
126int audit_q_len;
127int audit_pre_q_len;
128
129/*
130 * Audit queue control settings (minimum free, low/high water marks, etc.)
131 */
132struct au_qctrl audit_qctrl;
133
134/*
135 * Condition variable to signal to the worker that it has work to do:
136 * either new records are in the queue, or a log replacement is taking
137 * place.
138 */
139struct cv audit_worker_cv;
140
141/*
142 * Condition variable to flag when crossing the low watermark, meaning that
143 * threads blocked due to hitting the high watermark can wake up and continue
144 * to commit records.
145 */
146struct cv audit_watermark_cv;
147
148/*
149 * Condition variable for auditing threads wait on when in fail-stop mode.
150 * Threads wait on this CV forever (and ever), never seeing the light of
151 * day again.
152 */
153static struct cv audit_fail_cv;
154
155/*
156 * Construct an audit record for the passed thread.
157 */
158static int
159audit_record_ctor(void *mem, int size, void *arg, int flags)
160{
161 struct kaudit_record *ar;
162 struct thread *td;
163
164 KASSERT(sizeof(*ar) == size, ("audit_record_ctor: wrong size"));
165
166 td = arg;
167 ar = mem;
168 bzero(ar, sizeof(*ar));
169 ar->k_ar.ar_magic = AUDIT_RECORD_MAGIC;
170 nanotime(&ar->k_ar.ar_starttime);
171
172 /*
173 * Export the subject credential.
174 *
175 * XXXAUDIT: td_ucred access is OK without proc lock, but some other
176 * fields here may require the proc lock.
177 */
178 cru2x(td->td_ucred, &ar->k_ar.ar_subj_cred);
179 ar->k_ar.ar_subj_ruid = td->td_ucred->cr_ruid;
180 ar->k_ar.ar_subj_rgid = td->td_ucred->cr_rgid;
181 ar->k_ar.ar_subj_egid = td->td_ucred->cr_groups[0];
182 ar->k_ar.ar_subj_auid = td->td_proc->p_au->ai_auid;
183 ar->k_ar.ar_subj_asid = td->td_proc->p_au->ai_asid;
184 ar->k_ar.ar_subj_pid = td->td_proc->p_pid;
185 ar->k_ar.ar_subj_amask = td->td_proc->p_au->ai_mask;
186 ar->k_ar.ar_subj_term = td->td_proc->p_au->ai_termid;
187 bcopy(td->td_proc->p_comm, ar->k_ar.ar_subj_comm, MAXCOMLEN);
188
189 return (0);
190}
191
192static void
193audit_record_dtor(void *mem, int size, void *arg)
194{
195 struct kaudit_record *ar;
196
197 KASSERT(sizeof(*ar) == size, ("audit_record_dtor: wrong size"));
198
199 ar = mem;
200 if (ar->k_ar.ar_arg_upath1 != NULL)
201 free(ar->k_ar.ar_arg_upath1, M_AUDITPATH);
202 if (ar->k_ar.ar_arg_upath2 != NULL)
203 free(ar->k_ar.ar_arg_upath2, M_AUDITPATH);
204 if (ar->k_ar.ar_arg_text != NULL)
205 free(ar->k_ar.ar_arg_text, M_AUDITTEXT);
206 if (ar->k_udata != NULL)
207 free(ar->k_udata, M_AUDITDATA);
208}
209
210/*
211 * Initialize the Audit subsystem: configuration state, work queue,
212 * synchronization primitives, worker thread, and trigger device node. Also
213 * call into the BSM assembly code to initialize it.
214 */
215static void
216audit_init(void)
217{
218
219 printf("Security auditing service present\n");
220 audit_enabled = 0;
221 audit_suspended = 0;
222 audit_panic_on_write_fail = 0;
223 audit_fail_stop = 0;
224 audit_in_failure = 0;
225
226 audit_fstat.af_filesz = 0; /* '0' means unset, unbounded */
227 audit_fstat.af_currsz = 0;
228 audit_nae_mask.am_success = AU_NULL;
229 audit_nae_mask.am_failure = AU_NULL;
230
231 TAILQ_INIT(&audit_q);
232 audit_q_len = 0;
233 audit_pre_q_len = 0;
234 audit_qctrl.aq_hiwater = AQ_HIWATER;
235 audit_qctrl.aq_lowater = AQ_LOWATER;
236 audit_qctrl.aq_bufsz = AQ_BUFSZ;
237 audit_qctrl.aq_minfree = AU_FS_MINFREE;
238
239 mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF);
240 cv_init(&audit_worker_cv, "audit_worker_cv");
241 cv_init(&audit_watermark_cv, "audit_watermark_cv");
242 cv_init(&audit_fail_cv, "audit_fail_cv");
243
244 audit_record_zone = uma_zcreate("audit_record_zone",
245 sizeof(struct kaudit_record), audit_record_ctor,
246 audit_record_dtor, NULL, NULL, UMA_ALIGN_PTR, 0);
247
248 /* Initialize the BSM audit subsystem. */
249 kau_init();
250
251 audit_trigger_init();
252
253 /* Register shutdown handler. */
254 EVENTHANDLER_REGISTER(shutdown_pre_sync, audit_shutdown, NULL,
255 SHUTDOWN_PRI_FIRST);
256
257 /* Start audit worker thread. */
258 audit_worker_init();
259}
260
261SYSINIT(audit_init, SI_SUB_AUDIT, SI_ORDER_FIRST, audit_init, NULL)
262
263/*
264 * Drain the audit queue and close the log at shutdown. Note that this can
265 * be called both from the system shutdown path and also from audit
266 * configuration syscalls, so 'arg' and 'howto' are ignored.
267 */
268void
269audit_shutdown(void *arg, int howto)
270{
271
272 audit_rotate_vnode(NULL, NULL);
273}
274
275/*
276 * Return the current thread's audit record, if any.
277 */
278__inline__ struct kaudit_record *
279currecord(void)
280{
281
282 return (curthread->td_ar);
283}
284
285/*
286 * MPSAFE
287 *
288 * XXXAUDIT: There are a number of races present in the code below due to
289 * release and re-grab of the mutex. The code should be revised to become
290 * slightly less racy.
291 *
292 * XXXAUDIT: Shouldn't there be logic here to sleep waiting on available
293 * pre_q space, suspending the system call until there is room?
294 */
295struct kaudit_record *
296audit_new(int event, struct thread *td)
297{
298 struct kaudit_record *ar;
299 int no_record;
300
301 mtx_lock(&audit_mtx);
302 no_record = (audit_suspended || !audit_enabled);
303 mtx_unlock(&audit_mtx);
304 if (no_record)
305 return (NULL);
306
307 /*
308 * XXX: The number of outstanding uncommitted audit records is
309 * limited to the number of concurrent threads servicing system
310 * calls in the kernel.
311 */
312 ar = uma_zalloc_arg(audit_record_zone, td, M_WAITOK);
313 ar->k_ar.ar_event = event;
314
315 mtx_lock(&audit_mtx);
316 audit_pre_q_len++;
317 mtx_unlock(&audit_mtx);
318
319 return (ar);
320}
321
322void
323audit_free(struct kaudit_record *ar)
324{
325
326 uma_zfree(audit_record_zone, ar);
327}
328
329/*
330 * MPSAFE
331 */
332void
333audit_commit(struct kaudit_record *ar, int error, int retval)
334{
335 int sorf;
336 struct au_mask *aumask;
337
338 if (ar == NULL)
339 return;
340
341 /*
342 * Decide whether to commit the audit record by checking the
343 * error value from the system call and using the appropriate
344 * audit mask.
345 *
346 * XXXAUDIT: Synchronize access to audit_nae_mask?
347 */
348 if (ar->k_ar.ar_subj_auid == AU_DEFAUDITID)
349 aumask = &audit_nae_mask;
350 else
351 aumask = &ar->k_ar.ar_subj_amask;
352
353 if (error)
354 sorf = AU_PRS_FAILURE;
355 else
356 sorf = AU_PRS_SUCCESS;
357
358 switch(ar->k_ar.ar_event) {
359
360 case AUE_OPEN_RWTC:
361 /* The open syscall always writes a AUE_OPEN_RWTC event; change
362 * it to the proper type of event based on the flags and the
363 * error value.
364 */
365 ar->k_ar.ar_event = flags_and_error_to_openevent(
366 ar->k_ar.ar_arg_fflags, error);
367 break;
368
369 case AUE_SYSCTL:
370 ar->k_ar.ar_event = ctlname_to_sysctlevent(
371 ar->k_ar.ar_arg_ctlname, ar->k_ar.ar_valid_arg);
372 break;
373
374 case AUE_AUDITON:
375 /* Convert the auditon() command to an event */
376 ar->k_ar.ar_event = auditon_command_event(ar->k_ar.ar_arg_cmd);
377 break;
378 }
379
380 if (au_preselect(ar->k_ar.ar_event, aumask, sorf) != 0)
381 ar->k_ar_commit |= AR_COMMIT_KERNEL;
382
383 /*
384 * XXXRW: Why is this necessary? Should we ever accept a record that
385 * we're not willing to commit?
386 */
387 if ((ar->k_ar_commit & (AR_COMMIT_USER | AR_COMMIT_KERNEL)) == 0) {
388 mtx_lock(&audit_mtx);
389 audit_pre_q_len--;
390 mtx_unlock(&audit_mtx);
391 uma_zfree(audit_record_zone, ar);
392 return;
393 }
394
395 ar->k_ar.ar_errno = error;
396 ar->k_ar.ar_retval = retval;
397
398 /*
399 * We might want to do some system-wide post-filtering
400 * here at some point.
401 */
402
403 /*
404 * Timestamp system call end.
405 */
406 nanotime(&ar->k_ar.ar_endtime);
407
408 mtx_lock(&audit_mtx);
409
410 /*
411 * Note: it could be that some records initiated while audit was
412 * enabled should still be committed?
413 */
414 if (audit_suspended || !audit_enabled) {
415 audit_pre_q_len--;
416 mtx_unlock(&audit_mtx);
417 uma_zfree(audit_record_zone, ar);
418 return;
419 }
420
421 /*
422 * Constrain the number of committed audit records based on
423 * the configurable parameter.
424 */
425 while (audit_q_len >= audit_qctrl.aq_hiwater) {
426 AUDIT_PRINTF(("audit_commit: sleeping to wait for "
427 "audit queue to drain below high water mark\n"));
428 cv_wait(&audit_watermark_cv, &audit_mtx);
429 AUDIT_PRINTF(("audit_commit: woke up waiting for "
430 "audit queue draining\n"));
431 }
432
433 TAILQ_INSERT_TAIL(&audit_q, ar, k_q);
434 audit_q_len++;
435 audit_pre_q_len--;
436 cv_signal(&audit_worker_cv);
437 mtx_unlock(&audit_mtx);
438}
439
440/*
441 * audit_syscall_enter() is called on entry to each system call. It is
442 * responsible for deciding whether or not to audit the call (preselection),
443 * and if so, allocating a per-thread audit record. audit_new() will fill in
444 * basic thread/credential properties.
445 */
446void
447audit_syscall_enter(unsigned short code, struct thread *td)
448{
449 int audit_event;
450 struct au_mask *aumask;
451
452 KASSERT(td->td_ar == NULL, ("audit_syscall_enter: td->td_ar != NULL"));
453
454 /*
455 * In FreeBSD, each ABI has its own system call table, and hence
456 * mapping of system call codes to audit events. Convert the code to
457 * an audit event identifier using the process system call table
458 * reference. In Darwin, there's only one, so we use the global
459 * symbol for the system call table.
460 *
461 * XXXAUDIT: Should we audit that a bad system call was made, and if
462 * so, how?
463 */
464 if (code >= td->td_proc->p_sysent->sv_size)
465 return;
466
467 audit_event = td->td_proc->p_sysent->sv_table[code].sy_auevent;
468 if (audit_event == AUE_NULL)
469 return;
470
471 /*
472 * Check which audit mask to use; either the kernel non-attributable
473 * event mask or the process audit mask.
474 */
475 if (td->td_proc->p_au->ai_auid == AU_DEFAUDITID)
476 aumask = &audit_nae_mask;
477 else
478 aumask = &td->td_proc->p_au->ai_mask;
479
480 /*
481 * Allocate an audit record, if preselection allows it, and store
482 * in the thread for later use.
483 */
484 if (au_preselect(audit_event, aumask,
485 AU_PRS_FAILURE | AU_PRS_SUCCESS)) {
486 /*
487 * If we're out of space and need to suspend unprivileged
488 * processes, do that here rather than trying to allocate
489 * another audit record.
490 *
491 * XXXRW: We might wish to be able to continue here in the
492 * future, if the system recovers. That should be possible
493 * by means of checking the condition in a loop around
494 * cv_wait(). It might be desirable to reevaluate whether an
495 * audit record is still required for this event by
496 * re-calling au_preselect().
497 */
498 if (audit_in_failure && suser(td) != 0) {
499 cv_wait(&audit_fail_cv, &audit_mtx);
500 panic("audit_failing_stop: thread continued");
501 }
502 td->td_ar = audit_new(audit_event, td);
503 } else
504 td->td_ar = NULL;
505}
506
507/*
508 * audit_syscall_exit() is called from the return of every system call, or in
509 * the event of exit1(), during the execution of exit1(). It is responsible
510 * for committing the audit record, if any, along with return condition.
511 */
512void
513audit_syscall_exit(int error, struct thread *td)
514{
515 int retval;
516
517 /*
518 * Commit the audit record as desired; once we pass the record
519 * into audit_commit(), the memory is owned by the audit
520 * subsystem.
521 * The return value from the system call is stored on the user
522 * thread. If there was an error, the return value is set to -1,
523 * imitating the behavior of the cerror routine.
524 */
525 if (error)
526 retval = -1;
527 else
528 retval = td->td_retval[0];
529
530 audit_commit(td->td_ar, error, retval);
531 if (td->td_ar != NULL)
532 AUDIT_PRINTF(("audit record committed by pid %d\n",
533 td->td_proc->p_pid));
534 td->td_ar = NULL;
535
536}
537
538/*
539 * Allocate storage for a new process (init, or otherwise).
540 */
541void
542audit_proc_alloc(struct proc *p)
543{
544
545 KASSERT(p->p_au == NULL, ("audit_proc_alloc: p->p_au != NULL (%d)",
546 p->p_pid));
547 p->p_au = malloc(sizeof(*(p->p_au)), M_AUDITPROC, M_WAITOK);
548 /* XXXAUDIT: Zero? Slab allocate? */
549 //printf("audit_proc_alloc: pid %d p_au %p\n", p->p_pid, p->p_au);
550}
551
552/*
553 * Allocate storage for a new thread.
554 */
555void
556audit_thread_alloc(struct thread *td)
557{
558
559 td->td_ar = NULL;
560}
561
562/*
563 * Thread destruction.
564 */
565void
566audit_thread_free(struct thread *td)
567{
568
569 KASSERT(td->td_ar == NULL, ("audit_thread_free: td_ar != NULL"));
570}
571
572/*
573 * Initialize the audit information for the a process, presumably the first
574 * process in the system.
575 * XXX It is not clear what the initial values should be for audit ID,
576 * session ID, etc.
577 */
578void
579audit_proc_kproc0(struct proc *p)
580{
581
582 KASSERT(p->p_au != NULL, ("audit_proc_kproc0: p->p_au == NULL (%d)",
583 p->p_pid));
584 //printf("audit_proc_kproc0: pid %d p_au %p\n", p->p_pid, p->p_au);
585 bzero(p->p_au, sizeof(*(p)->p_au));
586}
587
588void
589audit_proc_init(struct proc *p)
590{
591
592 KASSERT(p->p_au != NULL, ("audit_proc_init: p->p_au == NULL (%d)",
593 p->p_pid));
594 //printf("audit_proc_init: pid %d p_au %p\n", p->p_pid, p->p_au);
595 bzero(p->p_au, sizeof(*(p)->p_au));
596 p->p_au->ai_auid = AU_DEFAUDITID;
597}
598
599/*
600 * Copy the audit info from the parent process to the child process when
601 * a fork takes place.
602 */
603void
604audit_proc_fork(struct proc *parent, struct proc *child)
605{
606
607 PROC_LOCK_ASSERT(parent, MA_OWNED);
608 PROC_LOCK_ASSERT(child, MA_OWNED);
609 KASSERT(parent->p_au != NULL,
610 ("audit_proc_fork: parent->p_au == NULL (%d)", parent->p_pid));
611 KASSERT(child->p_au != NULL,
612 ("audit_proc_fork: child->p_au == NULL (%d)", child->p_pid));
613 //printf("audit_proc_fork: parent pid %d p_au %p\n", parent->p_pid,
614 // parent->p_au);
615 //printf("audit_proc_fork: child pid %d p_au %p\n", child->p_pid,
616 // child->p_au);
617 bcopy(parent->p_au, child->p_au, sizeof(*child->p_au));
618 /*
619 * XXXAUDIT: Zero pointers to external memory, or assert they are
620 * zero?
621 */
622}
623
624/*
625 * Free the auditing structure for the process.
626 */
627void
628audit_proc_free(struct proc *p)
629{
630
631 KASSERT(p->p_au != NULL, ("p->p_au == NULL (%d)", p->p_pid));
632 //printf("audit_proc_free: pid %d p_au %p\n", p->p_pid, p->p_au);
633 /*
634 * XXXAUDIT: Assert that external memory pointers are NULL?
635 */
636 free(p->p_au, M_AUDITPROC);
637 p->p_au = NULL;
638}
2 * Copyright (c) 1999-2005 Apple Computer, Inc.
3 * Copyright (c) 2006 Robert N. M. Watson
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
15 * its contributors may be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR
22 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
27 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 *
30 * $FreeBSD: head/sys/security/audit/audit.c 159261 2006-06-05 13:43:57Z rwatson $
31 */
32
33#include <sys/param.h>
34#include <sys/condvar.h>
35#include <sys/conf.h>
36#include <sys/file.h>
37#include <sys/filedesc.h>
38#include <sys/fcntl.h>
39#include <sys/ipc.h>
40#include <sys/kernel.h>
41#include <sys/kthread.h>
42#include <sys/malloc.h>
43#include <sys/mount.h>
44#include <sys/namei.h>
45#include <sys/proc.h>
46#include <sys/queue.h>
47#include <sys/socket.h>
48#include <sys/socketvar.h>
49#include <sys/protosw.h>
50#include <sys/domain.h>
51#include <sys/sysproto.h>
52#include <sys/sysent.h>
53#include <sys/systm.h>
54#include <sys/ucred.h>
55#include <sys/uio.h>
56#include <sys/un.h>
57#include <sys/unistd.h>
58#include <sys/vnode.h>
59
60#include <bsm/audit.h>
61#include <bsm/audit_internal.h>
62#include <bsm/audit_kevents.h>
63
64#include <netinet/in.h>
65#include <netinet/in_pcb.h>
66
67#include <security/audit/audit.h>
68#include <security/audit/audit_private.h>
69
70#include <vm/uma.h>
71
72static uma_zone_t audit_record_zone;
73static MALLOC_DEFINE(M_AUDITPROC, "audit_proc", "Audit process storage");
74MALLOC_DEFINE(M_AUDITDATA, "audit_data", "Audit data storage");
75MALLOC_DEFINE(M_AUDITPATH, "audit_path", "Audit path storage");
76MALLOC_DEFINE(M_AUDITTEXT, "audit_text", "Audit text storage");
77
78/*
79 * Audit control settings that are set/read by system calls and are
80 * hence non-static.
81 */
82/*
83 * Define the audit control flags.
84 */
85int audit_enabled;
86int audit_suspended;
87
88/*
89 * Flags controlling behavior in low storage situations.
90 * Should we panic if a write fails? Should we fail stop
91 * if we're out of disk space?
92 */
93int audit_panic_on_write_fail;
94int audit_fail_stop;
95
96/*
97 * Are we currently "failing stop" due to out of disk space?
98 */
99int audit_in_failure;
100
101/*
102 * Global audit statistiscs.
103 */
104struct audit_fstat audit_fstat;
105
106/*
107 * Preselection mask for non-attributable events.
108 */
109struct au_mask audit_nae_mask;
110
111/*
112 * Mutex to protect global variables shared between various threads and
113 * processes.
114 */
115struct mtx audit_mtx;
116
117/*
118 * Queue of audit records ready for delivery to disk. We insert new
119 * records at the tail, and remove records from the head. Also,
120 * a count of the number of records used for checking queue depth.
121 * In addition, a counter of records that we have allocated but are
122 * not yet in the queue, which is needed to estimate the total
123 * size of the combined set of records outstanding in the system.
124 */
125struct kaudit_queue audit_q;
126int audit_q_len;
127int audit_pre_q_len;
128
129/*
130 * Audit queue control settings (minimum free, low/high water marks, etc.)
131 */
132struct au_qctrl audit_qctrl;
133
134/*
135 * Condition variable to signal to the worker that it has work to do:
136 * either new records are in the queue, or a log replacement is taking
137 * place.
138 */
139struct cv audit_worker_cv;
140
141/*
142 * Condition variable to flag when crossing the low watermark, meaning that
143 * threads blocked due to hitting the high watermark can wake up and continue
144 * to commit records.
145 */
146struct cv audit_watermark_cv;
147
148/*
149 * Condition variable for auditing threads wait on when in fail-stop mode.
150 * Threads wait on this CV forever (and ever), never seeing the light of
151 * day again.
152 */
153static struct cv audit_fail_cv;
154
155/*
156 * Construct an audit record for the passed thread.
157 */
158static int
159audit_record_ctor(void *mem, int size, void *arg, int flags)
160{
161 struct kaudit_record *ar;
162 struct thread *td;
163
164 KASSERT(sizeof(*ar) == size, ("audit_record_ctor: wrong size"));
165
166 td = arg;
167 ar = mem;
168 bzero(ar, sizeof(*ar));
169 ar->k_ar.ar_magic = AUDIT_RECORD_MAGIC;
170 nanotime(&ar->k_ar.ar_starttime);
171
172 /*
173 * Export the subject credential.
174 *
175 * XXXAUDIT: td_ucred access is OK without proc lock, but some other
176 * fields here may require the proc lock.
177 */
178 cru2x(td->td_ucred, &ar->k_ar.ar_subj_cred);
179 ar->k_ar.ar_subj_ruid = td->td_ucred->cr_ruid;
180 ar->k_ar.ar_subj_rgid = td->td_ucred->cr_rgid;
181 ar->k_ar.ar_subj_egid = td->td_ucred->cr_groups[0];
182 ar->k_ar.ar_subj_auid = td->td_proc->p_au->ai_auid;
183 ar->k_ar.ar_subj_asid = td->td_proc->p_au->ai_asid;
184 ar->k_ar.ar_subj_pid = td->td_proc->p_pid;
185 ar->k_ar.ar_subj_amask = td->td_proc->p_au->ai_mask;
186 ar->k_ar.ar_subj_term = td->td_proc->p_au->ai_termid;
187 bcopy(td->td_proc->p_comm, ar->k_ar.ar_subj_comm, MAXCOMLEN);
188
189 return (0);
190}
191
192static void
193audit_record_dtor(void *mem, int size, void *arg)
194{
195 struct kaudit_record *ar;
196
197 KASSERT(sizeof(*ar) == size, ("audit_record_dtor: wrong size"));
198
199 ar = mem;
200 if (ar->k_ar.ar_arg_upath1 != NULL)
201 free(ar->k_ar.ar_arg_upath1, M_AUDITPATH);
202 if (ar->k_ar.ar_arg_upath2 != NULL)
203 free(ar->k_ar.ar_arg_upath2, M_AUDITPATH);
204 if (ar->k_ar.ar_arg_text != NULL)
205 free(ar->k_ar.ar_arg_text, M_AUDITTEXT);
206 if (ar->k_udata != NULL)
207 free(ar->k_udata, M_AUDITDATA);
208}
209
210/*
211 * Initialize the Audit subsystem: configuration state, work queue,
212 * synchronization primitives, worker thread, and trigger device node. Also
213 * call into the BSM assembly code to initialize it.
214 */
215static void
216audit_init(void)
217{
218
219 printf("Security auditing service present\n");
220 audit_enabled = 0;
221 audit_suspended = 0;
222 audit_panic_on_write_fail = 0;
223 audit_fail_stop = 0;
224 audit_in_failure = 0;
225
226 audit_fstat.af_filesz = 0; /* '0' means unset, unbounded */
227 audit_fstat.af_currsz = 0;
228 audit_nae_mask.am_success = AU_NULL;
229 audit_nae_mask.am_failure = AU_NULL;
230
231 TAILQ_INIT(&audit_q);
232 audit_q_len = 0;
233 audit_pre_q_len = 0;
234 audit_qctrl.aq_hiwater = AQ_HIWATER;
235 audit_qctrl.aq_lowater = AQ_LOWATER;
236 audit_qctrl.aq_bufsz = AQ_BUFSZ;
237 audit_qctrl.aq_minfree = AU_FS_MINFREE;
238
239 mtx_init(&audit_mtx, "audit_mtx", NULL, MTX_DEF);
240 cv_init(&audit_worker_cv, "audit_worker_cv");
241 cv_init(&audit_watermark_cv, "audit_watermark_cv");
242 cv_init(&audit_fail_cv, "audit_fail_cv");
243
244 audit_record_zone = uma_zcreate("audit_record_zone",
245 sizeof(struct kaudit_record), audit_record_ctor,
246 audit_record_dtor, NULL, NULL, UMA_ALIGN_PTR, 0);
247
248 /* Initialize the BSM audit subsystem. */
249 kau_init();
250
251 audit_trigger_init();
252
253 /* Register shutdown handler. */
254 EVENTHANDLER_REGISTER(shutdown_pre_sync, audit_shutdown, NULL,
255 SHUTDOWN_PRI_FIRST);
256
257 /* Start audit worker thread. */
258 audit_worker_init();
259}
260
261SYSINIT(audit_init, SI_SUB_AUDIT, SI_ORDER_FIRST, audit_init, NULL)
262
263/*
264 * Drain the audit queue and close the log at shutdown. Note that this can
265 * be called both from the system shutdown path and also from audit
266 * configuration syscalls, so 'arg' and 'howto' are ignored.
267 */
268void
269audit_shutdown(void *arg, int howto)
270{
271
272 audit_rotate_vnode(NULL, NULL);
273}
274
275/*
276 * Return the current thread's audit record, if any.
277 */
278__inline__ struct kaudit_record *
279currecord(void)
280{
281
282 return (curthread->td_ar);
283}
284
285/*
286 * MPSAFE
287 *
288 * XXXAUDIT: There are a number of races present in the code below due to
289 * release and re-grab of the mutex. The code should be revised to become
290 * slightly less racy.
291 *
292 * XXXAUDIT: Shouldn't there be logic here to sleep waiting on available
293 * pre_q space, suspending the system call until there is room?
294 */
295struct kaudit_record *
296audit_new(int event, struct thread *td)
297{
298 struct kaudit_record *ar;
299 int no_record;
300
301 mtx_lock(&audit_mtx);
302 no_record = (audit_suspended || !audit_enabled);
303 mtx_unlock(&audit_mtx);
304 if (no_record)
305 return (NULL);
306
307 /*
308 * XXX: The number of outstanding uncommitted audit records is
309 * limited to the number of concurrent threads servicing system
310 * calls in the kernel.
311 */
312 ar = uma_zalloc_arg(audit_record_zone, td, M_WAITOK);
313 ar->k_ar.ar_event = event;
314
315 mtx_lock(&audit_mtx);
316 audit_pre_q_len++;
317 mtx_unlock(&audit_mtx);
318
319 return (ar);
320}
321
322void
323audit_free(struct kaudit_record *ar)
324{
325
326 uma_zfree(audit_record_zone, ar);
327}
328
329/*
330 * MPSAFE
331 */
332void
333audit_commit(struct kaudit_record *ar, int error, int retval)
334{
335 int sorf;
336 struct au_mask *aumask;
337
338 if (ar == NULL)
339 return;
340
341 /*
342 * Decide whether to commit the audit record by checking the
343 * error value from the system call and using the appropriate
344 * audit mask.
345 *
346 * XXXAUDIT: Synchronize access to audit_nae_mask?
347 */
348 if (ar->k_ar.ar_subj_auid == AU_DEFAUDITID)
349 aumask = &audit_nae_mask;
350 else
351 aumask = &ar->k_ar.ar_subj_amask;
352
353 if (error)
354 sorf = AU_PRS_FAILURE;
355 else
356 sorf = AU_PRS_SUCCESS;
357
358 switch(ar->k_ar.ar_event) {
359
360 case AUE_OPEN_RWTC:
361 /* The open syscall always writes a AUE_OPEN_RWTC event; change
362 * it to the proper type of event based on the flags and the
363 * error value.
364 */
365 ar->k_ar.ar_event = flags_and_error_to_openevent(
366 ar->k_ar.ar_arg_fflags, error);
367 break;
368
369 case AUE_SYSCTL:
370 ar->k_ar.ar_event = ctlname_to_sysctlevent(
371 ar->k_ar.ar_arg_ctlname, ar->k_ar.ar_valid_arg);
372 break;
373
374 case AUE_AUDITON:
375 /* Convert the auditon() command to an event */
376 ar->k_ar.ar_event = auditon_command_event(ar->k_ar.ar_arg_cmd);
377 break;
378 }
379
380 if (au_preselect(ar->k_ar.ar_event, aumask, sorf) != 0)
381 ar->k_ar_commit |= AR_COMMIT_KERNEL;
382
383 /*
384 * XXXRW: Why is this necessary? Should we ever accept a record that
385 * we're not willing to commit?
386 */
387 if ((ar->k_ar_commit & (AR_COMMIT_USER | AR_COMMIT_KERNEL)) == 0) {
388 mtx_lock(&audit_mtx);
389 audit_pre_q_len--;
390 mtx_unlock(&audit_mtx);
391 uma_zfree(audit_record_zone, ar);
392 return;
393 }
394
395 ar->k_ar.ar_errno = error;
396 ar->k_ar.ar_retval = retval;
397
398 /*
399 * We might want to do some system-wide post-filtering
400 * here at some point.
401 */
402
403 /*
404 * Timestamp system call end.
405 */
406 nanotime(&ar->k_ar.ar_endtime);
407
408 mtx_lock(&audit_mtx);
409
410 /*
411 * Note: it could be that some records initiated while audit was
412 * enabled should still be committed?
413 */
414 if (audit_suspended || !audit_enabled) {
415 audit_pre_q_len--;
416 mtx_unlock(&audit_mtx);
417 uma_zfree(audit_record_zone, ar);
418 return;
419 }
420
421 /*
422 * Constrain the number of committed audit records based on
423 * the configurable parameter.
424 */
425 while (audit_q_len >= audit_qctrl.aq_hiwater) {
426 AUDIT_PRINTF(("audit_commit: sleeping to wait for "
427 "audit queue to drain below high water mark\n"));
428 cv_wait(&audit_watermark_cv, &audit_mtx);
429 AUDIT_PRINTF(("audit_commit: woke up waiting for "
430 "audit queue draining\n"));
431 }
432
433 TAILQ_INSERT_TAIL(&audit_q, ar, k_q);
434 audit_q_len++;
435 audit_pre_q_len--;
436 cv_signal(&audit_worker_cv);
437 mtx_unlock(&audit_mtx);
438}
439
440/*
441 * audit_syscall_enter() is called on entry to each system call. It is
442 * responsible for deciding whether or not to audit the call (preselection),
443 * and if so, allocating a per-thread audit record. audit_new() will fill in
444 * basic thread/credential properties.
445 */
446void
447audit_syscall_enter(unsigned short code, struct thread *td)
448{
449 int audit_event;
450 struct au_mask *aumask;
451
452 KASSERT(td->td_ar == NULL, ("audit_syscall_enter: td->td_ar != NULL"));
453
454 /*
455 * In FreeBSD, each ABI has its own system call table, and hence
456 * mapping of system call codes to audit events. Convert the code to
457 * an audit event identifier using the process system call table
458 * reference. In Darwin, there's only one, so we use the global
459 * symbol for the system call table.
460 *
461 * XXXAUDIT: Should we audit that a bad system call was made, and if
462 * so, how?
463 */
464 if (code >= td->td_proc->p_sysent->sv_size)
465 return;
466
467 audit_event = td->td_proc->p_sysent->sv_table[code].sy_auevent;
468 if (audit_event == AUE_NULL)
469 return;
470
471 /*
472 * Check which audit mask to use; either the kernel non-attributable
473 * event mask or the process audit mask.
474 */
475 if (td->td_proc->p_au->ai_auid == AU_DEFAUDITID)
476 aumask = &audit_nae_mask;
477 else
478 aumask = &td->td_proc->p_au->ai_mask;
479
480 /*
481 * Allocate an audit record, if preselection allows it, and store
482 * in the thread for later use.
483 */
484 if (au_preselect(audit_event, aumask,
485 AU_PRS_FAILURE | AU_PRS_SUCCESS)) {
486 /*
487 * If we're out of space and need to suspend unprivileged
488 * processes, do that here rather than trying to allocate
489 * another audit record.
490 *
491 * XXXRW: We might wish to be able to continue here in the
492 * future, if the system recovers. That should be possible
493 * by means of checking the condition in a loop around
494 * cv_wait(). It might be desirable to reevaluate whether an
495 * audit record is still required for this event by
496 * re-calling au_preselect().
497 */
498 if (audit_in_failure && suser(td) != 0) {
499 cv_wait(&audit_fail_cv, &audit_mtx);
500 panic("audit_failing_stop: thread continued");
501 }
502 td->td_ar = audit_new(audit_event, td);
503 } else
504 td->td_ar = NULL;
505}
506
507/*
508 * audit_syscall_exit() is called from the return of every system call, or in
509 * the event of exit1(), during the execution of exit1(). It is responsible
510 * for committing the audit record, if any, along with return condition.
511 */
512void
513audit_syscall_exit(int error, struct thread *td)
514{
515 int retval;
516
517 /*
518 * Commit the audit record as desired; once we pass the record
519 * into audit_commit(), the memory is owned by the audit
520 * subsystem.
521 * The return value from the system call is stored on the user
522 * thread. If there was an error, the return value is set to -1,
523 * imitating the behavior of the cerror routine.
524 */
525 if (error)
526 retval = -1;
527 else
528 retval = td->td_retval[0];
529
530 audit_commit(td->td_ar, error, retval);
531 if (td->td_ar != NULL)
532 AUDIT_PRINTF(("audit record committed by pid %d\n",
533 td->td_proc->p_pid));
534 td->td_ar = NULL;
535
536}
537
538/*
539 * Allocate storage for a new process (init, or otherwise).
540 */
541void
542audit_proc_alloc(struct proc *p)
543{
544
545 KASSERT(p->p_au == NULL, ("audit_proc_alloc: p->p_au != NULL (%d)",
546 p->p_pid));
547 p->p_au = malloc(sizeof(*(p->p_au)), M_AUDITPROC, M_WAITOK);
548 /* XXXAUDIT: Zero? Slab allocate? */
549 //printf("audit_proc_alloc: pid %d p_au %p\n", p->p_pid, p->p_au);
550}
551
552/*
553 * Allocate storage for a new thread.
554 */
555void
556audit_thread_alloc(struct thread *td)
557{
558
559 td->td_ar = NULL;
560}
561
562/*
563 * Thread destruction.
564 */
565void
566audit_thread_free(struct thread *td)
567{
568
569 KASSERT(td->td_ar == NULL, ("audit_thread_free: td_ar != NULL"));
570}
571
572/*
573 * Initialize the audit information for the a process, presumably the first
574 * process in the system.
575 * XXX It is not clear what the initial values should be for audit ID,
576 * session ID, etc.
577 */
578void
579audit_proc_kproc0(struct proc *p)
580{
581
582 KASSERT(p->p_au != NULL, ("audit_proc_kproc0: p->p_au == NULL (%d)",
583 p->p_pid));
584 //printf("audit_proc_kproc0: pid %d p_au %p\n", p->p_pid, p->p_au);
585 bzero(p->p_au, sizeof(*(p)->p_au));
586}
587
588void
589audit_proc_init(struct proc *p)
590{
591
592 KASSERT(p->p_au != NULL, ("audit_proc_init: p->p_au == NULL (%d)",
593 p->p_pid));
594 //printf("audit_proc_init: pid %d p_au %p\n", p->p_pid, p->p_au);
595 bzero(p->p_au, sizeof(*(p)->p_au));
596 p->p_au->ai_auid = AU_DEFAUDITID;
597}
598
599/*
600 * Copy the audit info from the parent process to the child process when
601 * a fork takes place.
602 */
603void
604audit_proc_fork(struct proc *parent, struct proc *child)
605{
606
607 PROC_LOCK_ASSERT(parent, MA_OWNED);
608 PROC_LOCK_ASSERT(child, MA_OWNED);
609 KASSERT(parent->p_au != NULL,
610 ("audit_proc_fork: parent->p_au == NULL (%d)", parent->p_pid));
611 KASSERT(child->p_au != NULL,
612 ("audit_proc_fork: child->p_au == NULL (%d)", child->p_pid));
613 //printf("audit_proc_fork: parent pid %d p_au %p\n", parent->p_pid,
614 // parent->p_au);
615 //printf("audit_proc_fork: child pid %d p_au %p\n", child->p_pid,
616 // child->p_au);
617 bcopy(parent->p_au, child->p_au, sizeof(*child->p_au));
618 /*
619 * XXXAUDIT: Zero pointers to external memory, or assert they are
620 * zero?
621 */
622}
623
624/*
625 * Free the auditing structure for the process.
626 */
627void
628audit_proc_free(struct proc *p)
629{
630
631 KASSERT(p->p_au != NULL, ("p->p_au == NULL (%d)", p->p_pid));
632 //printf("audit_proc_free: pid %d p_au %p\n", p->p_pid, p->p_au);
633 /*
634 * XXXAUDIT: Assert that external memory pointers are NULL?
635 */
636 free(p->p_au, M_AUDITPROC);
637 p->p_au = NULL;
638}