1 /*-
2 * Copyright (c) 2006 Robert N. M. Watson
3 * Copyright (c) 2008-2009 Apple, Inc.
4 * All rights reserved.
5 *
6 * This software was developed by Robert Watson for the TrustedBSD Project.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/param.h>
31 #include <sys/condvar.h>
32 #include <sys/conf.h>
33 #include <sys/eventhandler.h>
34 #include <sys/filio.h>
35 #include <sys/kernel.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 #include <sys/poll.h>
40 #include <sys/proc.h>
41 #include <sys/queue.h>
42 #include <sys/rwlock.h>
43 #include <sys/selinfo.h>
44 #include <sys/sigio.h>
45 #include <sys/signal.h>
46 #include <sys/signalvar.h>
47 #include <sys/sx.h>
48 #include <sys/systm.h>
49 #include <sys/uio.h>
50
51 #include <security/audit/audit.h>
52 #include <security/audit/audit_ioctl.h>
53 #include <security/audit/audit_private.h>
54
55 /*
56 * Implementation of a clonable special device providing a live stream of BSM
57 * audit data. Consumers receive a "tee" of the system audit trail by
58 * default, but may also define alternative event selections using ioctls.
59 * This interface provides unreliable but timely access to audit events.
60 * Consumers should be very careful to avoid introducing event cycles.
61 */
62
63 /*
64 * Memory types.
65 */
66 static MALLOC_DEFINE(M_AUDIT_PIPE, "audit_pipe", "Audit pipes");
67 static MALLOC_DEFINE(M_AUDIT_PIPE_ENTRY, "audit_pipeent",
68 "Audit pipe entries and buffers");
69 static MALLOC_DEFINE(M_AUDIT_PIPE_PRESELECT, "audit_pipe_presel",
70 "Audit pipe preselection structure");
71
72 /*
73 * Audit pipe buffer parameters.
74 */
75 #define AUDIT_PIPE_QLIMIT_DEFAULT (128)
76 #define AUDIT_PIPE_QLIMIT_MIN (1)
77 #define AUDIT_PIPE_QLIMIT_MAX (1024)
78
79 /*
80 * Description of an entry in an audit_pipe.
81 */
82 struct audit_pipe_entry {
83 void *ape_record;
84 u_int ape_record_len;
85 TAILQ_ENTRY(audit_pipe_entry) ape_queue;
86 };
87
88 /*
89 * Audit pipes allow processes to express "interest" in the set of records
90 * that are delivered via the pipe. They do this in a similar manner to the
91 * mechanism for audit trail configuration, by expressing two global masks,
92 * and optionally expressing per-auid masks. The following data structure is
93 * the per-auid mask description. The global state is stored in the audit
94 * pipe data structure.
95 *
96 * We may want to consider a more space/time-efficient data structure once
97 * usage patterns for per-auid specifications are clear.
98 */
99 struct audit_pipe_preselect {
100 au_id_t app_auid;
101 au_mask_t app_mask;
102 TAILQ_ENTRY(audit_pipe_preselect) app_list;
103 };
104
105 /*
106 * Description of an individual audit_pipe. Consists largely of a bounded
107 * length queue.
108 */
109 #define AUDIT_PIPE_ASYNC 0x00000001
110 #define AUDIT_PIPE_NBIO 0x00000002
111 struct audit_pipe {
112 u_int ap_flags;
113
114 struct selinfo ap_selinfo;
115 struct sigio *ap_sigio;
116
117 /*
118 * Per-pipe mutex protecting most fields in this data structure.
119 */
120 struct mtx ap_mtx;
121
122 /*
123 * Per-pipe sleep lock serializing user-generated reads and flushes.
124 * uiomove() is called to copy out the current head record's data
125 * while the record remains in the queue, so we prevent other threads
126 * from removing it using this lock.
127 */
128 struct sx ap_sx;
129
130 /*
131 * Condition variable to signal when data has been delivered to a
132 * pipe.
133 */
134 struct cv ap_cv;
135
136 /*
137 * Various queue-reated variables: qlen and qlimit are a count of
138 * records in the queue; qbyteslen is the number of bytes of data
139 * across all records, and qoffset is the amount read so far of the
140 * first record in the queue. The number of bytes available for
141 * reading in the queue is qbyteslen - qoffset.
142 */
143 u_int ap_qlen;
144 u_int ap_qlimit;
145 u_int ap_qbyteslen;
146 u_int ap_qoffset;
147
148 /*
149 * Per-pipe operation statistics.
150 */
151 u_int64_t ap_inserts; /* Records added. */
152 u_int64_t ap_reads; /* Records read. */
153 u_int64_t ap_drops; /* Records dropped. */
154
155 /*
156 * Fields relating to pipe interest: global masks for unmatched
157 * processes (attributable, non-attributable), and a list of specific
158 * interest specifications by auid.
159 */
160 int ap_preselect_mode;
161 au_mask_t ap_preselect_flags;
162 au_mask_t ap_preselect_naflags;
163 TAILQ_HEAD(, audit_pipe_preselect) ap_preselect_list;
164
165 /*
166 * Current pending record list. Protected by a combination of ap_mtx
167 * and ap_sx. Note particularly that *both* locks are required to
168 * remove a record from the head of the queue, as an in-progress read
169 * may sleep while copying and therefore cannot hold ap_mtx.
170 */
171 TAILQ_HEAD(, audit_pipe_entry) ap_queue;
172
173 /*
174 * Global pipe list.
175 */
176 TAILQ_ENTRY(audit_pipe) ap_list;
177 };
178
179 #define AUDIT_PIPE_LOCK(ap) mtx_lock(&(ap)->ap_mtx)
180 #define AUDIT_PIPE_LOCK_ASSERT(ap) mtx_assert(&(ap)->ap_mtx, MA_OWNED)
181 #define AUDIT_PIPE_LOCK_DESTROY(ap) mtx_destroy(&(ap)->ap_mtx)
182 #define AUDIT_PIPE_LOCK_INIT(ap) mtx_init(&(ap)->ap_mtx, \
183 "audit_pipe_mtx", NULL, MTX_DEF)
184 #define AUDIT_PIPE_UNLOCK(ap) mtx_unlock(&(ap)->ap_mtx)
185 #define AUDIT_PIPE_MTX(ap) (&(ap)->ap_mtx)
186
187 #define AUDIT_PIPE_SX_LOCK_DESTROY(ap) sx_destroy(&(ap)->ap_sx)
188 #define AUDIT_PIPE_SX_LOCK_INIT(ap) sx_init(&(ap)->ap_sx, "audit_pipe_sx")
189 #define AUDIT_PIPE_SX_XLOCK_ASSERT(ap) sx_assert(&(ap)->ap_sx, SA_XLOCKED)
190 #define AUDIT_PIPE_SX_XLOCK_SIG(ap) sx_xlock_sig(&(ap)->ap_sx)
191 #define AUDIT_PIPE_SX_XUNLOCK(ap) sx_xunlock(&(ap)->ap_sx)
192
193 /*
194 * Global list of audit pipes, rwlock to protect it. Individual record
195 * queues on pipes are protected by per-pipe locks; these locks synchronize
196 * between threads walking the list to deliver to individual pipes and add/
197 * remove of pipes, and are mostly acquired for read.
198 */
199 static TAILQ_HEAD(, audit_pipe) audit_pipe_list;
200 static struct rwlock audit_pipe_lock;
201
202 #define AUDIT_PIPE_LIST_LOCK_INIT() rw_init(&audit_pipe_lock, \
203 "audit_pipe_list_lock")
204 #define AUDIT_PIPE_LIST_LOCK_DESTROY() rw_destroy(&audit_pipe_lock)
205 #define AUDIT_PIPE_LIST_RLOCK() rw_rlock(&audit_pipe_lock)
206 #define AUDIT_PIPE_LIST_RUNLOCK() rw_runlock(&audit_pipe_lock)
207 #define AUDIT_PIPE_LIST_WLOCK() rw_wlock(&audit_pipe_lock)
208 #define AUDIT_PIPE_LIST_WLOCK_ASSERT() rw_assert(&audit_pipe_lock, \
209 RA_WLOCKED)
210 #define AUDIT_PIPE_LIST_WUNLOCK() rw_wunlock(&audit_pipe_lock)
211
212 /*
213 * Audit pipe device.
214 */
215 static struct cdev *audit_pipe_dev;
216
217 #define AUDIT_PIPE_NAME "auditpipe"
218
219 /*
220 * Special device methods and definition.
221 */
222 static d_open_t audit_pipe_open;
223 static d_read_t audit_pipe_read;
224 static d_ioctl_t audit_pipe_ioctl;
225 static d_poll_t audit_pipe_poll;
226 static d_kqfilter_t audit_pipe_kqfilter;
227
228 static struct cdevsw audit_pipe_cdevsw = {
229 .d_version = D_VERSION,
230 .d_open = audit_pipe_open,
231 .d_read = audit_pipe_read,
232 .d_ioctl = audit_pipe_ioctl,
233 .d_poll = audit_pipe_poll,
234 .d_kqfilter = audit_pipe_kqfilter,
235 .d_name = AUDIT_PIPE_NAME,
236 };
237
238 static int audit_pipe_kqread(struct knote *note, long hint);
239 static void audit_pipe_kqdetach(struct knote *note);
240
241 static struct filterops audit_pipe_read_filterops = {
242 .f_isfd = 1,
243 .f_attach = NULL,
244 .f_detach = audit_pipe_kqdetach,
245 .f_event = audit_pipe_kqread,
246 };
247
248 /*
249 * Some global statistics on audit pipes.
250 */
251 static int audit_pipe_count; /* Current number of pipes. */
252 static u_int64_t audit_pipe_ever; /* Pipes ever allocated. */
253 static u_int64_t audit_pipe_records; /* Records seen. */
254 static u_int64_t audit_pipe_drops; /* Global record drop count. */
255
256 /*
257 * Free an audit pipe entry.
258 */
259 static void
audit_pipe_entry_free(struct audit_pipe_entry * ape)260 audit_pipe_entry_free(struct audit_pipe_entry *ape)
261 {
262
263 free(ape->ape_record, M_AUDIT_PIPE_ENTRY);
264 free(ape, M_AUDIT_PIPE_ENTRY);
265 }
266
267 /*
268 * Find an audit pipe preselection specification for an auid, if any.
269 */
270 static struct audit_pipe_preselect *
audit_pipe_preselect_find(struct audit_pipe * ap,au_id_t auid)271 audit_pipe_preselect_find(struct audit_pipe *ap, au_id_t auid)
272 {
273 struct audit_pipe_preselect *app;
274
275 AUDIT_PIPE_LOCK_ASSERT(ap);
276
277 TAILQ_FOREACH(app, &ap->ap_preselect_list, app_list) {
278 if (app->app_auid == auid)
279 return (app);
280 }
281 return (NULL);
282 }
283
284 /*
285 * Query the per-pipe mask for a specific auid.
286 */
287 static int
audit_pipe_preselect_get(struct audit_pipe * ap,au_id_t auid,au_mask_t * maskp)288 audit_pipe_preselect_get(struct audit_pipe *ap, au_id_t auid,
289 au_mask_t *maskp)
290 {
291 struct audit_pipe_preselect *app;
292 int error;
293
294 AUDIT_PIPE_LOCK(ap);
295 app = audit_pipe_preselect_find(ap, auid);
296 if (app != NULL) {
297 *maskp = app->app_mask;
298 error = 0;
299 } else
300 error = ENOENT;
301 AUDIT_PIPE_UNLOCK(ap);
302 return (error);
303 }
304
305 /*
306 * Set the per-pipe mask for a specific auid. Add a new entry if needed;
307 * otherwise, update the current entry.
308 */
309 static void
audit_pipe_preselect_set(struct audit_pipe * ap,au_id_t auid,au_mask_t mask)310 audit_pipe_preselect_set(struct audit_pipe *ap, au_id_t auid, au_mask_t mask)
311 {
312 struct audit_pipe_preselect *app, *app_new;
313
314 /*
315 * Pessimistically assume that the auid doesn't already have a mask
316 * set, and allocate. We will free it if it is unneeded.
317 */
318 app_new = malloc(sizeof(*app_new), M_AUDIT_PIPE_PRESELECT, M_WAITOK);
319 AUDIT_PIPE_LOCK(ap);
320 app = audit_pipe_preselect_find(ap, auid);
321 if (app == NULL) {
322 app = app_new;
323 app_new = NULL;
324 app->app_auid = auid;
325 TAILQ_INSERT_TAIL(&ap->ap_preselect_list, app, app_list);
326 }
327 app->app_mask = mask;
328 AUDIT_PIPE_UNLOCK(ap);
329 if (app_new != NULL)
330 free(app_new, M_AUDIT_PIPE_PRESELECT);
331 }
332
333 /*
334 * Delete a per-auid mask on an audit pipe.
335 */
336 static int
audit_pipe_preselect_delete(struct audit_pipe * ap,au_id_t auid)337 audit_pipe_preselect_delete(struct audit_pipe *ap, au_id_t auid)
338 {
339 struct audit_pipe_preselect *app;
340 int error;
341
342 AUDIT_PIPE_LOCK(ap);
343 app = audit_pipe_preselect_find(ap, auid);
344 if (app != NULL) {
345 TAILQ_REMOVE(&ap->ap_preselect_list, app, app_list);
346 error = 0;
347 } else
348 error = ENOENT;
349 AUDIT_PIPE_UNLOCK(ap);
350 if (app != NULL)
351 free(app, M_AUDIT_PIPE_PRESELECT);
352 return (error);
353 }
354
355 /*
356 * Delete all per-auid masks on an audit pipe.
357 */
358 static void
audit_pipe_preselect_flush_locked(struct audit_pipe * ap)359 audit_pipe_preselect_flush_locked(struct audit_pipe *ap)
360 {
361 struct audit_pipe_preselect *app;
362
363 AUDIT_PIPE_LOCK_ASSERT(ap);
364
365 while ((app = TAILQ_FIRST(&ap->ap_preselect_list)) != NULL) {
366 TAILQ_REMOVE(&ap->ap_preselect_list, app, app_list);
367 free(app, M_AUDIT_PIPE_PRESELECT);
368 }
369 }
370
371 static void
audit_pipe_preselect_flush(struct audit_pipe * ap)372 audit_pipe_preselect_flush(struct audit_pipe *ap)
373 {
374
375 AUDIT_PIPE_LOCK(ap);
376 audit_pipe_preselect_flush_locked(ap);
377 AUDIT_PIPE_UNLOCK(ap);
378 }
379
380 /*-
381 * Determine whether a specific audit pipe matches a record with these
382 * properties. Algorithm is as follows:
383 *
384 * - If the pipe is configured to track the default trail configuration, then
385 * use the results of global preselection matching.
386 * - If not, search for a specifically configured auid entry matching the
387 * event. If an entry is found, use that.
388 * - Otherwise, use the default flags or naflags configured for the pipe.
389 */
390 static int
audit_pipe_preselect_check(struct audit_pipe * ap,au_id_t auid,au_event_t event,au_class_t class,int sorf,int trail_preselect)391 audit_pipe_preselect_check(struct audit_pipe *ap, au_id_t auid,
392 au_event_t event, au_class_t class, int sorf, int trail_preselect)
393 {
394 struct audit_pipe_preselect *app;
395
396 AUDIT_PIPE_LOCK_ASSERT(ap);
397
398 switch (ap->ap_preselect_mode) {
399 case AUDITPIPE_PRESELECT_MODE_TRAIL:
400 return (trail_preselect);
401
402 case AUDITPIPE_PRESELECT_MODE_LOCAL:
403 app = audit_pipe_preselect_find(ap, auid);
404 if (app == NULL) {
405 if (auid == AU_DEFAUDITID)
406 return (au_preselect(event, class,
407 &ap->ap_preselect_naflags, sorf));
408 else
409 return (au_preselect(event, class,
410 &ap->ap_preselect_flags, sorf));
411 } else
412 return (au_preselect(event, class, &app->app_mask,
413 sorf));
414
415 default:
416 panic("audit_pipe_preselect_check: mode %d",
417 ap->ap_preselect_mode);
418 }
419
420 return (0);
421 }
422
423 /*
424 * Determine whether there exists a pipe interested in a record with specific
425 * properties.
426 */
427 int
audit_pipe_preselect(au_id_t auid,au_event_t event,au_class_t class,int sorf,int trail_preselect)428 audit_pipe_preselect(au_id_t auid, au_event_t event, au_class_t class,
429 int sorf, int trail_preselect)
430 {
431 struct audit_pipe *ap;
432
433 /* Lockless read to avoid acquiring the global lock if not needed. */
434 if (TAILQ_EMPTY(&audit_pipe_list))
435 return (0);
436
437 AUDIT_PIPE_LIST_RLOCK();
438 TAILQ_FOREACH(ap, &audit_pipe_list, ap_list) {
439 AUDIT_PIPE_LOCK(ap);
440 if (audit_pipe_preselect_check(ap, auid, event, class, sorf,
441 trail_preselect)) {
442 AUDIT_PIPE_UNLOCK(ap);
443 AUDIT_PIPE_LIST_RUNLOCK();
444 return (1);
445 }
446 AUDIT_PIPE_UNLOCK(ap);
447 }
448 AUDIT_PIPE_LIST_RUNLOCK();
449 return (0);
450 }
451
452 /*
453 * Append individual record to a queue -- allocate queue-local buffer, and
454 * add to the queue. If the queue is full or we can't allocate memory, drop
455 * the newest record.
456 */
457 static void
audit_pipe_append(struct audit_pipe * ap,void * record,u_int record_len)458 audit_pipe_append(struct audit_pipe *ap, void *record, u_int record_len)
459 {
460 struct audit_pipe_entry *ape;
461
462 AUDIT_PIPE_LOCK_ASSERT(ap);
463
464 if (ap->ap_qlen >= ap->ap_qlimit) {
465 ap->ap_drops++;
466 audit_pipe_drops++;
467 return;
468 }
469
470 ape = malloc(sizeof(*ape), M_AUDIT_PIPE_ENTRY, M_NOWAIT | M_ZERO);
471 if (ape == NULL) {
472 ap->ap_drops++;
473 audit_pipe_drops++;
474 return;
475 }
476
477 ape->ape_record = malloc(record_len, M_AUDIT_PIPE_ENTRY, M_NOWAIT);
478 if (ape->ape_record == NULL) {
479 free(ape, M_AUDIT_PIPE_ENTRY);
480 ap->ap_drops++;
481 audit_pipe_drops++;
482 return;
483 }
484
485 bcopy(record, ape->ape_record, record_len);
486 ape->ape_record_len = record_len;
487
488 TAILQ_INSERT_TAIL(&ap->ap_queue, ape, ape_queue);
489 ap->ap_inserts++;
490 ap->ap_qlen++;
491 ap->ap_qbyteslen += ape->ape_record_len;
492 selwakeuppri(&ap->ap_selinfo, PSOCK);
493 KNOTE_LOCKED(&ap->ap_selinfo.si_note, 0);
494 if (ap->ap_flags & AUDIT_PIPE_ASYNC)
495 pgsigio(&ap->ap_sigio, SIGIO, 0);
496 cv_broadcast(&ap->ap_cv);
497 }
498
499 /*
500 * audit_pipe_submit(): audit_worker submits audit records via this
501 * interface, which arranges for them to be delivered to pipe queues.
502 */
503 void
audit_pipe_submit(au_id_t auid,au_event_t event,au_class_t class,int sorf,int trail_select,void * record,u_int record_len)504 audit_pipe_submit(au_id_t auid, au_event_t event, au_class_t class, int sorf,
505 int trail_select, void *record, u_int record_len)
506 {
507 struct audit_pipe *ap;
508
509 /*
510 * Lockless read to avoid lock overhead if pipes are not in use.
511 */
512 if (TAILQ_FIRST(&audit_pipe_list) == NULL)
513 return;
514
515 AUDIT_PIPE_LIST_RLOCK();
516 TAILQ_FOREACH(ap, &audit_pipe_list, ap_list) {
517 AUDIT_PIPE_LOCK(ap);
518 if (audit_pipe_preselect_check(ap, auid, event, class, sorf,
519 trail_select))
520 audit_pipe_append(ap, record, record_len);
521 AUDIT_PIPE_UNLOCK(ap);
522 }
523 AUDIT_PIPE_LIST_RUNLOCK();
524
525 /* Unlocked increment. */
526 audit_pipe_records++;
527 }
528
529 /*
530 * audit_pipe_submit_user(): the same as audit_pipe_submit(), except that
531 * since we don't currently have selection information available, it is
532 * delivered to the pipe unconditionally.
533 *
534 * XXXRW: This is a bug. The BSM check routine for submitting a user record
535 * should parse that information and return it.
536 */
537 void
audit_pipe_submit_user(void * record,u_int record_len)538 audit_pipe_submit_user(void *record, u_int record_len)
539 {
540 struct audit_pipe *ap;
541
542 /*
543 * Lockless read to avoid lock overhead if pipes are not in use.
544 */
545 if (TAILQ_FIRST(&audit_pipe_list) == NULL)
546 return;
547
548 AUDIT_PIPE_LIST_RLOCK();
549 TAILQ_FOREACH(ap, &audit_pipe_list, ap_list) {
550 AUDIT_PIPE_LOCK(ap);
551 audit_pipe_append(ap, record, record_len);
552 AUDIT_PIPE_UNLOCK(ap);
553 }
554 AUDIT_PIPE_LIST_RUNLOCK();
555
556 /* Unlocked increment. */
557 audit_pipe_records++;
558 }
559
560 /*
561 * Allocate a new audit pipe. Connects the pipe, on success, to the global
562 * list and updates statistics.
563 */
564 static struct audit_pipe *
audit_pipe_alloc(void)565 audit_pipe_alloc(void)
566 {
567 struct audit_pipe *ap;
568
569 ap = malloc(sizeof(*ap), M_AUDIT_PIPE, M_NOWAIT | M_ZERO);
570 if (ap == NULL)
571 return (NULL);
572 ap->ap_qlimit = AUDIT_PIPE_QLIMIT_DEFAULT;
573 TAILQ_INIT(&ap->ap_queue);
574 knlist_init_mtx(&ap->ap_selinfo.si_note, AUDIT_PIPE_MTX(ap));
575 AUDIT_PIPE_LOCK_INIT(ap);
576 AUDIT_PIPE_SX_LOCK_INIT(ap);
577 cv_init(&ap->ap_cv, "audit_pipe");
578
579 /*
580 * Default flags, naflags, and auid-specific preselection settings to
581 * 0. Initialize the mode to the global trail so that if praudit(1)
582 * is run on /dev/auditpipe, it sees events associated with the
583 * default trail. Pipe-aware application can clear the flag, set
584 * custom masks, and flush the pipe as needed.
585 */
586 bzero(&ap->ap_preselect_flags, sizeof(ap->ap_preselect_flags));
587 bzero(&ap->ap_preselect_naflags, sizeof(ap->ap_preselect_naflags));
588 TAILQ_INIT(&ap->ap_preselect_list);
589 ap->ap_preselect_mode = AUDITPIPE_PRESELECT_MODE_TRAIL;
590
591 /*
592 * Add to global list and update global statistics.
593 */
594 AUDIT_PIPE_LIST_WLOCK();
595 TAILQ_INSERT_HEAD(&audit_pipe_list, ap, ap_list);
596 audit_pipe_count++;
597 audit_pipe_ever++;
598 AUDIT_PIPE_LIST_WUNLOCK();
599
600 return (ap);
601 }
602
603 /*
604 * Flush all records currently present in an audit pipe; assume mutex is held.
605 */
606 static void
audit_pipe_flush(struct audit_pipe * ap)607 audit_pipe_flush(struct audit_pipe *ap)
608 {
609 struct audit_pipe_entry *ape;
610
611 AUDIT_PIPE_LOCK_ASSERT(ap);
612
613 while ((ape = TAILQ_FIRST(&ap->ap_queue)) != NULL) {
614 TAILQ_REMOVE(&ap->ap_queue, ape, ape_queue);
615 ap->ap_qbyteslen -= ape->ape_record_len;
616 audit_pipe_entry_free(ape);
617 ap->ap_qlen--;
618 }
619 ap->ap_qoffset = 0;
620
621 KASSERT(ap->ap_qlen == 0, ("audit_pipe_free: ap_qbyteslen"));
622 KASSERT(ap->ap_qbyteslen == 0, ("audit_pipe_flush: ap_qbyteslen"));
623 }
624
625 /*
626 * Free an audit pipe; this means freeing all preselection state and all
627 * records in the pipe. Assumes global write lock and pipe mutex are held to
628 * prevent any new records from being inserted during the free, and that the
629 * audit pipe is still on the global list.
630 */
631 static void
audit_pipe_free(struct audit_pipe * ap)632 audit_pipe_free(struct audit_pipe *ap)
633 {
634
635 AUDIT_PIPE_LIST_WLOCK_ASSERT();
636 AUDIT_PIPE_LOCK_ASSERT(ap);
637
638 audit_pipe_preselect_flush_locked(ap);
639 audit_pipe_flush(ap);
640 cv_destroy(&ap->ap_cv);
641 AUDIT_PIPE_SX_LOCK_DESTROY(ap);
642 AUDIT_PIPE_LOCK_DESTROY(ap);
643 seldrain(&ap->ap_selinfo);
644 knlist_destroy(&ap->ap_selinfo.si_note);
645 TAILQ_REMOVE(&audit_pipe_list, ap, ap_list);
646 free(ap, M_AUDIT_PIPE);
647 audit_pipe_count--;
648 }
649
650 static void
audit_pipe_dtor(void * arg)651 audit_pipe_dtor(void *arg)
652 {
653 struct audit_pipe *ap;
654
655 ap = arg;
656 funsetown(&ap->ap_sigio);
657 AUDIT_PIPE_LIST_WLOCK();
658 AUDIT_PIPE_LOCK(ap);
659 audit_pipe_free(ap);
660 AUDIT_PIPE_LIST_WUNLOCK();
661 }
662
663 /*
664 * Audit pipe open method. Explicit privilege check isn't used as this
665 * allows file permissions on the special device to be used to grant audit
666 * review access. Those file permissions should be managed carefully.
667 */
668 static int
audit_pipe_open(struct cdev * dev,int oflags,int devtype,struct thread * td)669 audit_pipe_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
670 {
671 struct audit_pipe *ap;
672 int error;
673
674 ap = audit_pipe_alloc();
675 if (ap == NULL)
676 return (ENOMEM);
677 fsetown(td->td_proc->p_pid, &ap->ap_sigio);
678 error = devfs_set_cdevpriv(ap, audit_pipe_dtor);
679 if (error != 0)
680 audit_pipe_dtor(ap);
681 return (error);
682 }
683
684 /*
685 * Audit pipe ioctl() routine. Handle file descriptor and audit pipe layer
686 * commands.
687 */
688 static int
audit_pipe_ioctl(struct cdev * dev,u_long cmd,caddr_t data,int flag,struct thread * td)689 audit_pipe_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag,
690 struct thread *td)
691 {
692 struct auditpipe_ioctl_preselect *aip;
693 struct audit_pipe *ap;
694 au_mask_t *maskp;
695 int error, mode;
696 au_id_t auid;
697
698 error = devfs_get_cdevpriv((void **)&ap);
699 if (error != 0)
700 return (error);
701
702 /*
703 * Audit pipe ioctls: first come standard device node ioctls, then
704 * manipulation of pipe settings, and finally, statistics query
705 * ioctls.
706 */
707 switch (cmd) {
708 case FIONBIO:
709 AUDIT_PIPE_LOCK(ap);
710 if (*(int *)data)
711 ap->ap_flags |= AUDIT_PIPE_NBIO;
712 else
713 ap->ap_flags &= ~AUDIT_PIPE_NBIO;
714 AUDIT_PIPE_UNLOCK(ap);
715 error = 0;
716 break;
717
718 case FIONREAD:
719 AUDIT_PIPE_LOCK(ap);
720 *(int *)data = ap->ap_qbyteslen - ap->ap_qoffset;
721 AUDIT_PIPE_UNLOCK(ap);
722 error = 0;
723 break;
724
725 case FIOASYNC:
726 AUDIT_PIPE_LOCK(ap);
727 if (*(int *)data)
728 ap->ap_flags |= AUDIT_PIPE_ASYNC;
729 else
730 ap->ap_flags &= ~AUDIT_PIPE_ASYNC;
731 AUDIT_PIPE_UNLOCK(ap);
732 error = 0;
733 break;
734
735 case FIOSETOWN:
736 error = fsetown(*(int *)data, &ap->ap_sigio);
737 break;
738
739 case FIOGETOWN:
740 *(int *)data = fgetown(&ap->ap_sigio);
741 error = 0;
742 break;
743
744 case AUDITPIPE_GET_QLEN:
745 *(u_int *)data = ap->ap_qlen;
746 error = 0;
747 break;
748
749 case AUDITPIPE_GET_QLIMIT:
750 *(u_int *)data = ap->ap_qlimit;
751 error = 0;
752 break;
753
754 case AUDITPIPE_SET_QLIMIT:
755 /* Lockless integer write. */
756 if (*(u_int *)data >= AUDIT_PIPE_QLIMIT_MIN &&
757 *(u_int *)data <= AUDIT_PIPE_QLIMIT_MAX) {
758 ap->ap_qlimit = *(u_int *)data;
759 error = 0;
760 } else
761 error = EINVAL;
762 break;
763
764 case AUDITPIPE_GET_QLIMIT_MIN:
765 *(u_int *)data = AUDIT_PIPE_QLIMIT_MIN;
766 error = 0;
767 break;
768
769 case AUDITPIPE_GET_QLIMIT_MAX:
770 *(u_int *)data = AUDIT_PIPE_QLIMIT_MAX;
771 error = 0;
772 break;
773
774 case AUDITPIPE_GET_PRESELECT_FLAGS:
775 AUDIT_PIPE_LOCK(ap);
776 maskp = (au_mask_t *)data;
777 *maskp = ap->ap_preselect_flags;
778 AUDIT_PIPE_UNLOCK(ap);
779 error = 0;
780 break;
781
782 case AUDITPIPE_SET_PRESELECT_FLAGS:
783 AUDIT_PIPE_LOCK(ap);
784 maskp = (au_mask_t *)data;
785 ap->ap_preselect_flags = *maskp;
786 AUDIT_PIPE_UNLOCK(ap);
787 error = 0;
788 break;
789
790 case AUDITPIPE_GET_PRESELECT_NAFLAGS:
791 AUDIT_PIPE_LOCK(ap);
792 maskp = (au_mask_t *)data;
793 *maskp = ap->ap_preselect_naflags;
794 AUDIT_PIPE_UNLOCK(ap);
795 error = 0;
796 break;
797
798 case AUDITPIPE_SET_PRESELECT_NAFLAGS:
799 AUDIT_PIPE_LOCK(ap);
800 maskp = (au_mask_t *)data;
801 ap->ap_preselect_naflags = *maskp;
802 AUDIT_PIPE_UNLOCK(ap);
803 error = 0;
804 break;
805
806 case AUDITPIPE_GET_PRESELECT_AUID:
807 aip = (struct auditpipe_ioctl_preselect *)data;
808 error = audit_pipe_preselect_get(ap, aip->aip_auid,
809 &aip->aip_mask);
810 break;
811
812 case AUDITPIPE_SET_PRESELECT_AUID:
813 aip = (struct auditpipe_ioctl_preselect *)data;
814 audit_pipe_preselect_set(ap, aip->aip_auid, aip->aip_mask);
815 error = 0;
816 break;
817
818 case AUDITPIPE_DELETE_PRESELECT_AUID:
819 auid = *(au_id_t *)data;
820 error = audit_pipe_preselect_delete(ap, auid);
821 break;
822
823 case AUDITPIPE_FLUSH_PRESELECT_AUID:
824 audit_pipe_preselect_flush(ap);
825 error = 0;
826 break;
827
828 case AUDITPIPE_GET_PRESELECT_MODE:
829 AUDIT_PIPE_LOCK(ap);
830 *(int *)data = ap->ap_preselect_mode;
831 AUDIT_PIPE_UNLOCK(ap);
832 error = 0;
833 break;
834
835 case AUDITPIPE_SET_PRESELECT_MODE:
836 mode = *(int *)data;
837 switch (mode) {
838 case AUDITPIPE_PRESELECT_MODE_TRAIL:
839 case AUDITPIPE_PRESELECT_MODE_LOCAL:
840 AUDIT_PIPE_LOCK(ap);
841 ap->ap_preselect_mode = mode;
842 AUDIT_PIPE_UNLOCK(ap);
843 error = 0;
844 break;
845
846 default:
847 error = EINVAL;
848 }
849 break;
850
851 case AUDITPIPE_FLUSH:
852 if (AUDIT_PIPE_SX_XLOCK_SIG(ap) != 0)
853 return (EINTR);
854 AUDIT_PIPE_LOCK(ap);
855 audit_pipe_flush(ap);
856 AUDIT_PIPE_UNLOCK(ap);
857 AUDIT_PIPE_SX_XUNLOCK(ap);
858 error = 0;
859 break;
860
861 case AUDITPIPE_GET_MAXAUDITDATA:
862 *(u_int *)data = MAXAUDITDATA;
863 error = 0;
864 break;
865
866 case AUDITPIPE_GET_INSERTS:
867 *(u_int *)data = ap->ap_inserts;
868 error = 0;
869 break;
870
871 case AUDITPIPE_GET_READS:
872 *(u_int *)data = ap->ap_reads;
873 error = 0;
874 break;
875
876 case AUDITPIPE_GET_DROPS:
877 *(u_int *)data = ap->ap_drops;
878 error = 0;
879 break;
880
881 case AUDITPIPE_GET_TRUNCATES:
882 *(u_int *)data = 0;
883 error = 0;
884 break;
885
886 default:
887 error = ENOTTY;
888 }
889 return (error);
890 }
891
892 /*
893 * Audit pipe read. Read one or more partial or complete records to user
894 * memory.
895 */
896 static int
audit_pipe_read(struct cdev * dev,struct uio * uio,int flag)897 audit_pipe_read(struct cdev *dev, struct uio *uio, int flag)
898 {
899 struct audit_pipe_entry *ape;
900 struct audit_pipe *ap;
901 u_int toread;
902 int error;
903
904 error = devfs_get_cdevpriv((void **)&ap);
905 if (error != 0)
906 return (error);
907
908 /*
909 * We hold an sx(9) lock over read and flush because we rely on the
910 * stability of a record in the queue during uiomove(9).
911 */
912 if (AUDIT_PIPE_SX_XLOCK_SIG(ap) != 0)
913 return (EINTR);
914 AUDIT_PIPE_LOCK(ap);
915 while (TAILQ_EMPTY(&ap->ap_queue)) {
916 if (ap->ap_flags & AUDIT_PIPE_NBIO) {
917 AUDIT_PIPE_UNLOCK(ap);
918 AUDIT_PIPE_SX_XUNLOCK(ap);
919 return (EAGAIN);
920 }
921 error = cv_wait_sig(&ap->ap_cv, AUDIT_PIPE_MTX(ap));
922 if (error) {
923 AUDIT_PIPE_UNLOCK(ap);
924 AUDIT_PIPE_SX_XUNLOCK(ap);
925 return (error);
926 }
927 }
928
929 /*
930 * Copy as many remaining bytes from the current record to userspace
931 * as we can. Keep processing records until we run out of records in
932 * the queue, or until the user buffer runs out of space.
933 *
934 * Note: we rely on the SX lock to maintain ape's stability here.
935 */
936 ap->ap_reads++;
937 while ((ape = TAILQ_FIRST(&ap->ap_queue)) != NULL &&
938 uio->uio_resid > 0) {
939 AUDIT_PIPE_LOCK_ASSERT(ap);
940
941 KASSERT(ape->ape_record_len > ap->ap_qoffset,
942 ("audit_pipe_read: record_len > qoffset (1)"));
943 toread = MIN(ape->ape_record_len - ap->ap_qoffset,
944 uio->uio_resid);
945 AUDIT_PIPE_UNLOCK(ap);
946 error = uiomove((char *)ape->ape_record + ap->ap_qoffset,
947 toread, uio);
948 if (error) {
949 AUDIT_PIPE_SX_XUNLOCK(ap);
950 return (error);
951 }
952
953 /*
954 * If the copy succeeded, update book-keeping, and if no
955 * bytes remain in the current record, free it.
956 */
957 AUDIT_PIPE_LOCK(ap);
958 KASSERT(TAILQ_FIRST(&ap->ap_queue) == ape,
959 ("audit_pipe_read: queue out of sync after uiomove"));
960 ap->ap_qoffset += toread;
961 KASSERT(ape->ape_record_len >= ap->ap_qoffset,
962 ("audit_pipe_read: record_len >= qoffset (2)"));
963 if (ap->ap_qoffset == ape->ape_record_len) {
964 TAILQ_REMOVE(&ap->ap_queue, ape, ape_queue);
965 ap->ap_qbyteslen -= ape->ape_record_len;
966 audit_pipe_entry_free(ape);
967 ap->ap_qlen--;
968 ap->ap_qoffset = 0;
969 }
970 }
971 AUDIT_PIPE_UNLOCK(ap);
972 AUDIT_PIPE_SX_XUNLOCK(ap);
973 return (0);
974 }
975
976 /*
977 * Audit pipe poll.
978 */
979 static int
audit_pipe_poll(struct cdev * dev,int events,struct thread * td)980 audit_pipe_poll(struct cdev *dev, int events, struct thread *td)
981 {
982 struct audit_pipe *ap;
983 int error, revents;
984
985 revents = 0;
986 error = devfs_get_cdevpriv((void **)&ap);
987 if (error != 0)
988 return (error);
989 if (events & (POLLIN | POLLRDNORM)) {
990 AUDIT_PIPE_LOCK(ap);
991 if (TAILQ_FIRST(&ap->ap_queue) != NULL)
992 revents |= events & (POLLIN | POLLRDNORM);
993 else
994 selrecord(td, &ap->ap_selinfo);
995 AUDIT_PIPE_UNLOCK(ap);
996 }
997 return (revents);
998 }
999
1000 /*
1001 * Audit pipe kqfilter.
1002 */
1003 static int
audit_pipe_kqfilter(struct cdev * dev,struct knote * kn)1004 audit_pipe_kqfilter(struct cdev *dev, struct knote *kn)
1005 {
1006 struct audit_pipe *ap;
1007 int error;
1008
1009 error = devfs_get_cdevpriv((void **)&ap);
1010 if (error != 0)
1011 return (error);
1012 if (kn->kn_filter != EVFILT_READ)
1013 return (EINVAL);
1014
1015 kn->kn_fop = &audit_pipe_read_filterops;
1016 kn->kn_hook = ap;
1017
1018 AUDIT_PIPE_LOCK(ap);
1019 knlist_add(&ap->ap_selinfo.si_note, kn, 1);
1020 AUDIT_PIPE_UNLOCK(ap);
1021 return (0);
1022 }
1023
1024 /*
1025 * Return true if there are records available for reading on the pipe.
1026 */
1027 static int
audit_pipe_kqread(struct knote * kn,long hint)1028 audit_pipe_kqread(struct knote *kn, long hint)
1029 {
1030 struct audit_pipe *ap;
1031
1032 ap = (struct audit_pipe *)kn->kn_hook;
1033 AUDIT_PIPE_LOCK_ASSERT(ap);
1034
1035 if (ap->ap_qlen != 0) {
1036 kn->kn_data = ap->ap_qbyteslen - ap->ap_qoffset;
1037 return (1);
1038 } else {
1039 kn->kn_data = 0;
1040 return (0);
1041 }
1042 }
1043
1044 /*
1045 * Detach kqueue state from audit pipe.
1046 */
1047 static void
audit_pipe_kqdetach(struct knote * kn)1048 audit_pipe_kqdetach(struct knote *kn)
1049 {
1050 struct audit_pipe *ap;
1051
1052 ap = (struct audit_pipe *)kn->kn_hook;
1053 AUDIT_PIPE_LOCK(ap);
1054 knlist_remove(&ap->ap_selinfo.si_note, kn, 1);
1055 AUDIT_PIPE_UNLOCK(ap);
1056 }
1057
1058 /*
1059 * Initialize the audit pipe system.
1060 */
1061 static void
audit_pipe_init(void * unused)1062 audit_pipe_init(void *unused)
1063 {
1064
1065 TAILQ_INIT(&audit_pipe_list);
1066 AUDIT_PIPE_LIST_LOCK_INIT();
1067 audit_pipe_dev = make_dev(&audit_pipe_cdevsw, 0, UID_ROOT,
1068 GID_WHEEL, 0600, "%s", AUDIT_PIPE_NAME);
1069 if (audit_pipe_dev == NULL) {
1070 AUDIT_PIPE_LIST_LOCK_DESTROY();
1071 panic("Can't initialize audit pipe subsystem");
1072 }
1073 }
1074
1075 SYSINIT(audit_pipe_init, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, audit_pipe_init,
1076 NULL);
1077