1/*
2 * Copyright (c) 1999-2009 Apple Inc.
3 * Copyright (c) 2005 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 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
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD$");
33
34#include <sys/param.h>
35#include <sys/fcntl.h>
36#include <sys/filedesc.h>
37#include <sys/libkern.h>
38#include <sys/malloc.h>
39#include <sys/mount.h>
40#include <sys/proc.h>
41#include <sys/rwlock.h>
42#include <sys/sem.h>
43#include <sys/sbuf.h>
44#include <sys/syscall.h>
45#include <sys/sysctl.h>
46#include <sys/sysent.h>
47#include <sys/vnode.h>
48
49#include <bsm/audit.h>
50#include <bsm/audit_kevents.h>
51#include <security/audit/audit.h>
52#include <security/audit/audit_private.h>
53
54/*
55 * Hash table functions for the audit event number to event class mask
56 * mapping.
57 */
58#define	EVCLASSMAP_HASH_TABLE_SIZE	251
59struct evclass_elem {
60	au_event_t event;
61	au_class_t class;
62	LIST_ENTRY(evclass_elem) entry;
63};
64struct evclass_list {
65	LIST_HEAD(, evclass_elem) head;
66};
67
68static MALLOC_DEFINE(M_AUDITEVCLASS, "audit_evclass", "Audit event class");
69static struct rwlock		evclass_lock;
70static struct evclass_list	evclass_hash[EVCLASSMAP_HASH_TABLE_SIZE];
71
72#define	EVCLASS_LOCK_INIT()	rw_init(&evclass_lock, "evclass_lock")
73#define	EVCLASS_RLOCK()		rw_rlock(&evclass_lock)
74#define	EVCLASS_RUNLOCK()	rw_runlock(&evclass_lock)
75#define	EVCLASS_WLOCK()		rw_wlock(&evclass_lock)
76#define	EVCLASS_WUNLOCK()	rw_wunlock(&evclass_lock)
77
78struct aue_open_event {
79	int		aoe_flags;
80	au_event_t	aoe_event;
81};
82
83static const struct aue_open_event aue_open[] = {
84	{ O_RDONLY,					AUE_OPEN_R },
85	{ (O_RDONLY | O_CREAT),				AUE_OPEN_RC },
86	{ (O_RDONLY | O_CREAT | O_TRUNC),		AUE_OPEN_RTC },
87	{ (O_RDONLY | O_TRUNC),				AUE_OPEN_RT },
88	{ O_RDWR,					AUE_OPEN_RW },
89	{ (O_RDWR | O_CREAT),				AUE_OPEN_RWC },
90	{ (O_RDWR | O_CREAT | O_TRUNC),			AUE_OPEN_RWTC },
91	{ (O_RDWR | O_TRUNC),				AUE_OPEN_RWT },
92	{ O_WRONLY,					AUE_OPEN_W },
93	{ (O_WRONLY | O_CREAT),				AUE_OPEN_WC },
94	{ (O_WRONLY | O_CREAT | O_TRUNC),		AUE_OPEN_WTC },
95	{ (O_WRONLY | O_TRUNC),				AUE_OPEN_WT },
96};
97static const int aue_open_count = sizeof(aue_open) / sizeof(aue_open[0]);
98
99static const struct aue_open_event aue_openat[] = {
100	{ O_RDONLY,					AUE_OPENAT_R },
101	{ (O_RDONLY | O_CREAT),				AUE_OPENAT_RC },
102	{ (O_RDONLY | O_CREAT | O_TRUNC),		AUE_OPENAT_RTC },
103	{ (O_RDONLY | O_TRUNC),				AUE_OPENAT_RT },
104	{ O_RDWR,					AUE_OPENAT_RW },
105	{ (O_RDWR | O_CREAT),				AUE_OPENAT_RWC },
106	{ (O_RDWR | O_CREAT | O_TRUNC),			AUE_OPENAT_RWTC },
107	{ (O_RDWR | O_TRUNC),				AUE_OPENAT_RWT },
108	{ O_WRONLY,					AUE_OPENAT_W },
109	{ (O_WRONLY | O_CREAT),				AUE_OPENAT_WC },
110	{ (O_WRONLY | O_CREAT | O_TRUNC),		AUE_OPENAT_WTC },
111	{ (O_WRONLY | O_TRUNC),				AUE_OPENAT_WT },
112};
113static const int aue_openat_count = sizeof(aue_openat) / sizeof(aue_openat[0]);
114
115/*
116 * Look up the class for an audit event in the class mapping table.
117 */
118au_class_t
119au_event_class(au_event_t event)
120{
121	struct evclass_list *evcl;
122	struct evclass_elem *evc;
123	au_class_t class;
124
125	EVCLASS_RLOCK();
126	evcl = &evclass_hash[event % EVCLASSMAP_HASH_TABLE_SIZE];
127	class = 0;
128	LIST_FOREACH(evc, &evcl->head, entry) {
129		if (evc->event == event) {
130			class = evc->class;
131			goto out;
132		}
133	}
134out:
135	EVCLASS_RUNLOCK();
136	return (class);
137}
138
139/*
140 * Insert a event to class mapping. If the event already exists in the
141 * mapping, then replace the mapping with the new one.
142 *
143 * XXX There is currently no constraints placed on the number of mappings.
144 * May want to either limit to a number, or in terms of memory usage.
145 */
146void
147au_evclassmap_insert(au_event_t event, au_class_t class)
148{
149	struct evclass_list *evcl;
150	struct evclass_elem *evc, *evc_new;
151
152	/*
153	 * Pessimistically, always allocate storage before acquiring mutex.
154	 * Free if there is already a mapping for this event.
155	 */
156	evc_new = malloc(sizeof(*evc), M_AUDITEVCLASS, M_WAITOK);
157
158	EVCLASS_WLOCK();
159	evcl = &evclass_hash[event % EVCLASSMAP_HASH_TABLE_SIZE];
160	LIST_FOREACH(evc, &evcl->head, entry) {
161		if (evc->event == event) {
162			evc->class = class;
163			EVCLASS_WUNLOCK();
164			free(evc_new, M_AUDITEVCLASS);
165			return;
166		}
167	}
168	evc = evc_new;
169	evc->event = event;
170	evc->class = class;
171	LIST_INSERT_HEAD(&evcl->head, evc, entry);
172	EVCLASS_WUNLOCK();
173}
174
175void
176au_evclassmap_init(void)
177{
178	int i;
179
180	EVCLASS_LOCK_INIT();
181	for (i = 0; i < EVCLASSMAP_HASH_TABLE_SIZE; i++)
182		LIST_INIT(&evclass_hash[i].head);
183
184	/*
185	 * Set up the initial event to class mapping for system calls.
186	 *
187	 * XXXRW: Really, this should walk all possible audit events, not all
188	 * native ABI system calls, as there may be audit events reachable
189	 * only through non-native system calls.  It also seems a shame to
190	 * frob the mutex this early.
191	 */
192	for (i = 0; i < SYS_MAXSYSCALL; i++) {
193		if (sysent[i].sy_auevent != AUE_NULL)
194			au_evclassmap_insert(sysent[i].sy_auevent, 0);
195	}
196}
197
198/*
199 * Check whether an event is aditable by comparing the mask of classes this
200 * event is part of against the given mask.
201 */
202int
203au_preselect(au_event_t event, au_class_t class, au_mask_t *mask_p, int sorf)
204{
205	au_class_t effmask = 0;
206
207	if (mask_p == NULL)
208		return (-1);
209
210	/*
211	 * Perform the actual check of the masks against the event.
212	 */
213	if (sorf & AU_PRS_SUCCESS)
214		effmask |= (mask_p->am_success & class);
215
216	if (sorf & AU_PRS_FAILURE)
217		effmask |= (mask_p->am_failure & class);
218
219	if (effmask)
220		return (1);
221	else
222		return (0);
223}
224
225/*
226 * Convert sysctl names and present arguments to events.
227 */
228au_event_t
229audit_ctlname_to_sysctlevent(int name[], uint64_t valid_arg)
230{
231
232	/* can't parse it - so return the worst case */
233	if ((valid_arg & (ARG_CTLNAME | ARG_LEN)) != (ARG_CTLNAME | ARG_LEN))
234		return (AUE_SYSCTL);
235
236	switch (name[0]) {
237	/* non-admin "lookups" treat them special */
238	case KERN_OSTYPE:
239	case KERN_OSRELEASE:
240	case KERN_OSREV:
241	case KERN_VERSION:
242	case KERN_ARGMAX:
243	case KERN_CLOCKRATE:
244	case KERN_BOOTTIME:
245	case KERN_POSIX1:
246	case KERN_NGROUPS:
247	case KERN_JOB_CONTROL:
248	case KERN_SAVED_IDS:
249	case KERN_OSRELDATE:
250	case KERN_DUMMY:
251		return (AUE_SYSCTL_NONADMIN);
252
253	/* only treat the changeable controls as admin */
254	case KERN_MAXVNODES:
255	case KERN_MAXPROC:
256	case KERN_MAXFILES:
257	case KERN_MAXPROCPERUID:
258	case KERN_MAXFILESPERPROC:
259	case KERN_HOSTID:
260	case KERN_SECURELVL:
261	case KERN_HOSTNAME:
262	case KERN_VNODE:
263	case KERN_PROC:
264	case KERN_FILE:
265	case KERN_PROF:
266	case KERN_NISDOMAINNAME:
267	case KERN_UPDATEINTERVAL:
268	case KERN_NTP_PLL:
269	case KERN_BOOTFILE:
270	case KERN_DUMPDEV:
271	case KERN_IPC:
272	case KERN_PS_STRINGS:
273	case KERN_USRSTACK:
274	case KERN_LOGSIGEXIT:
275	case KERN_IOV_MAX:
276	case KERN_MAXID:
277		return ((valid_arg & ARG_VALUE) ?
278		    AUE_SYSCTL : AUE_SYSCTL_NONADMIN);
279
280	default:
281		return (AUE_SYSCTL);
282	}
283	/* NOTREACHED */
284}
285
286/*
287 * Convert an open flags specifier into a specific type of open event for
288 * auditing purposes.
289 */
290au_event_t
291audit_flags_and_error_to_openevent(int oflags, int error)
292{
293	int i;
294
295	/*
296	 * Need to check only those flags we care about.
297	 */
298	oflags = oflags & (O_RDONLY | O_CREAT | O_TRUNC | O_RDWR | O_WRONLY);
299	for (i = 0; i < aue_open_count; i++) {
300		if (aue_open[i].aoe_flags == oflags)
301			return (aue_open[i].aoe_event);
302	}
303	return (AUE_OPEN);
304}
305
306au_event_t
307audit_flags_and_error_to_openatevent(int oflags, int error)
308{
309	int i;
310
311	/*
312	 * Need to check only those flags we care about.
313	 */
314	oflags = oflags & (O_RDONLY | O_CREAT | O_TRUNC | O_RDWR | O_WRONLY);
315	for (i = 0; i < aue_openat_count; i++) {
316		if (aue_openat[i].aoe_flags == oflags)
317			return (aue_openat[i].aoe_event);
318	}
319	return (AUE_OPENAT);
320}
321
322/*
323 * Convert a MSGCTL command to a specific event.
324 */
325au_event_t
326audit_msgctl_to_event(int cmd)
327{
328
329	switch (cmd) {
330	case IPC_RMID:
331		return (AUE_MSGCTL_RMID);
332
333	case IPC_SET:
334		return (AUE_MSGCTL_SET);
335
336	case IPC_STAT:
337		return (AUE_MSGCTL_STAT);
338
339	default:
340		/* We will audit a bad command. */
341		return (AUE_MSGCTL);
342	}
343}
344
345/*
346 * Convert a SEMCTL command to a specific event.
347 */
348au_event_t
349audit_semctl_to_event(int cmd)
350{
351
352	switch (cmd) {
353	case GETALL:
354		return (AUE_SEMCTL_GETALL);
355
356	case GETNCNT:
357		return (AUE_SEMCTL_GETNCNT);
358
359	case GETPID:
360		return (AUE_SEMCTL_GETPID);
361
362	case GETVAL:
363		return (AUE_SEMCTL_GETVAL);
364
365	case GETZCNT:
366		return (AUE_SEMCTL_GETZCNT);
367
368	case IPC_RMID:
369		return (AUE_SEMCTL_RMID);
370
371	case IPC_SET:
372		return (AUE_SEMCTL_SET);
373
374	case SETALL:
375		return (AUE_SEMCTL_SETALL);
376
377	case SETVAL:
378		return (AUE_SEMCTL_SETVAL);
379
380	case IPC_STAT:
381		return (AUE_SEMCTL_STAT);
382
383	default:
384		/* We will audit a bad command. */
385		return (AUE_SEMCTL);
386	}
387}
388
389/*
390 * Convert a command for the auditon() system call to a audit event.
391 */
392au_event_t
393auditon_command_event(int cmd)
394{
395
396	switch(cmd) {
397	case A_GETPOLICY:
398		return (AUE_AUDITON_GPOLICY);
399
400	case A_SETPOLICY:
401		return (AUE_AUDITON_SPOLICY);
402
403	case A_GETKMASK:
404		return (AUE_AUDITON_GETKMASK);
405
406	case A_SETKMASK:
407		return (AUE_AUDITON_SETKMASK);
408
409	case A_GETQCTRL:
410		return (AUE_AUDITON_GQCTRL);
411
412	case A_SETQCTRL:
413		return (AUE_AUDITON_SQCTRL);
414
415	case A_GETCWD:
416		return (AUE_AUDITON_GETCWD);
417
418	case A_GETCAR:
419		return (AUE_AUDITON_GETCAR);
420
421	case A_GETSTAT:
422		return (AUE_AUDITON_GETSTAT);
423
424	case A_SETSTAT:
425		return (AUE_AUDITON_SETSTAT);
426
427	case A_SETUMASK:
428		return (AUE_AUDITON_SETUMASK);
429
430	case A_SETSMASK:
431		return (AUE_AUDITON_SETSMASK);
432
433	case A_GETCOND:
434		return (AUE_AUDITON_GETCOND);
435
436	case A_SETCOND:
437		return (AUE_AUDITON_SETCOND);
438
439	case A_GETCLASS:
440		return (AUE_AUDITON_GETCLASS);
441
442	case A_SETCLASS:
443		return (AUE_AUDITON_SETCLASS);
444
445	case A_GETPINFO:
446	case A_SETPMASK:
447	case A_SETFSIZE:
448	case A_GETFSIZE:
449	case A_GETPINFO_ADDR:
450	case A_GETKAUDIT:
451	case A_SETKAUDIT:
452	default:
453		return (AUE_AUDITON);	/* No special record */
454	}
455}
456
457/*
458 * Create a canonical path from given path by prefixing either the root
459 * directory, or the current working directory.  If the process working
460 * directory is NULL, we could use 'rootvnode' to obtain the root directory,
461 * but this results in a volfs name written to the audit log. So we will
462 * leave the filename starting with '/' in the audit log in this case.
463 */
464void
465audit_canon_path(struct thread *td, int dirfd, char *path, char *cpath)
466{
467	struct vnode *cvnp, *rvnp;
468	char *rbuf, *fbuf, *copy;
469	struct filedesc *fdp;
470	struct sbuf sbf;
471	int error, needslash;
472
473	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "%s: at %s:%d",
474	    __func__,  __FILE__, __LINE__);
475
476	copy = path;
477	rvnp = cvnp = NULL;
478	fdp = td->td_proc->p_fd;
479	FILEDESC_SLOCK(fdp);
480	/*
481	 * Make sure that we handle the chroot(2) case.  If there is an
482	 * alternate root directory, prepend it to the audited pathname.
483	 */
484	if (fdp->fd_rdir != NULL && fdp->fd_rdir != rootvnode) {
485		rvnp = fdp->fd_rdir;
486		vhold(rvnp);
487	}
488	/*
489	 * If the supplied path is relative, make sure we capture the current
490	 * working directory so we can prepend it to the supplied relative
491	 * path.
492	 */
493	if (*path != '/') {
494		if (dirfd == AT_FDCWD) {
495			cvnp = fdp->fd_cdir;
496			vhold(cvnp);
497		} else {
498			/* XXX: fgetvp() that vhold()s vnode instead of vref()ing it would be better */
499			error = fgetvp(td, dirfd, NULL, &cvnp);
500			if (error) {
501				cpath[0] = '\0';
502				if (rvnp != NULL)
503					vdrop(rvnp);
504				return;
505			}
506			vhold(cvnp);
507			vrele(cvnp);
508		}
509		needslash = (fdp->fd_rdir != cvnp);
510	} else {
511		needslash = 1;
512	}
513	FILEDESC_SUNLOCK(fdp);
514	/*
515	 * NB: We require that the supplied array be at least MAXPATHLEN bytes
516	 * long.  If this is not the case, then we can run into serious trouble.
517	 */
518	(void) sbuf_new(&sbf, cpath, MAXPATHLEN, SBUF_FIXEDLEN);
519	/*
520	 * Strip leading forward slashes.
521	 */
522	while (*copy == '/')
523		copy++;
524	/*
525	 * Make sure we handle chroot(2) and prepend the global path to these
526	 * environments.
527	 *
528	 * NB: vn_fullpath(9) on FreeBSD is less reliable than vn_getpath(9)
529	 * on Darwin.  As a result, this may need some additional attention
530	 * in the future.
531	 */
532	if (rvnp != NULL) {
533		error = vn_fullpath_global(td, rvnp, &rbuf, &fbuf);
534		vdrop(rvnp);
535		if (error) {
536			cpath[0] = '\0';
537			if (cvnp != NULL)
538				vdrop(cvnp);
539			return;
540		}
541		(void) sbuf_cat(&sbf, rbuf);
542		free(fbuf, M_TEMP);
543	}
544	if (cvnp != NULL) {
545		error = vn_fullpath(td, cvnp, &rbuf, &fbuf);
546		vdrop(cvnp);
547		if (error) {
548			cpath[0] = '\0';
549			return;
550		}
551		(void) sbuf_cat(&sbf, rbuf);
552		free(fbuf, M_TEMP);
553	}
554	if (needslash)
555		(void) sbuf_putc(&sbf, '/');
556	/*
557	 * Now that we have processed any alternate root and relative path
558	 * names, add the supplied pathname.
559	 */
560        (void) sbuf_cat(&sbf, copy);
561	/*
562	 * One or more of the previous sbuf operations could have resulted in
563	 * the supplied buffer being overflowed.  Check to see if this is the
564	 * case.
565	 */
566	if (sbuf_error(&sbf) != 0) {
567		cpath[0] = '\0';
568		return;
569	}
570	sbuf_finish(&sbf);
571}
572