Commit | Line | Data |
---|---|---|
85c8721f | 1 | /* audit.c -- Auditing support |
1da177e4 LT |
2 | * Gateway between the kernel (e.g., selinux) and the user-space audit daemon. |
3 | * System-call specific features have moved to auditsc.c | |
4 | * | |
5 | * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. | |
6 | * All Rights Reserved. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
21 | * | |
22 | * Written by Rickard E. (Rik) Faith <faith@redhat.com> | |
23 | * | |
24 | * Goals: 1) Integrate fully with SELinux. | |
25 | * 2) Minimal run-time overhead: | |
26 | * a) Minimal when syscall auditing is disabled (audit_enable=0). | |
27 | * b) Small when syscall auditing is enabled and no audit record | |
28 | * is generated (defer as much work as possible to record | |
29 | * generation time): | |
30 | * i) context is allocated, | |
31 | * ii) names from getname are stored without a copy, and | |
32 | * iii) inode information stored from path_lookup. | |
33 | * 3) Ability to disable syscall auditing at boot time (audit=0). | |
34 | * 4) Usable by other parts of the kernel (if audit_log* is called, | |
35 | * then a syscall record will be generated automatically for the | |
36 | * current syscall). | |
37 | * 5) Netlink interface to user-space. | |
38 | * 6) Support low-overhead kernel-based filtering to minimize the | |
39 | * information that must be passed to user-space. | |
40 | * | |
85c8721f | 41 | * Example user-space utilities: http://people.redhat.com/sgrubb/audit/ |
1da177e4 LT |
42 | */ |
43 | ||
44 | #include <linux/init.h> | |
45 | #include <asm/atomic.h> | |
46 | #include <asm/types.h> | |
47 | #include <linux/mm.h> | |
48 | #include <linux/module.h> | |
49 | ||
50 | #include <linux/audit.h> | |
51 | ||
52 | #include <net/sock.h> | |
53 | #include <linux/skbuff.h> | |
54 | #include <linux/netlink.h> | |
55 | ||
56 | /* No auditing will take place until audit_initialized != 0. | |
57 | * (Initialization happens after skb_init is called.) */ | |
58 | static int audit_initialized; | |
59 | ||
60 | /* No syscall auditing will take place unless audit_enabled != 0. */ | |
61 | int audit_enabled; | |
62 | ||
63 | /* Default state when kernel boots without any parameters. */ | |
64 | static int audit_default; | |
65 | ||
66 | /* If auditing cannot proceed, audit_failure selects what happens. */ | |
67 | static int audit_failure = AUDIT_FAIL_PRINTK; | |
68 | ||
69 | /* If audit records are to be written to the netlink socket, audit_pid | |
70 | * contains the (non-zero) pid. */ | |
71 | static int audit_pid; | |
72 | ||
73 | /* If audit_limit is non-zero, limit the rate of sending audit records | |
74 | * to that number per second. This prevents DoS attacks, but results in | |
75 | * audit records being dropped. */ | |
76 | static int audit_rate_limit; | |
77 | ||
78 | /* Number of outstanding audit_buffers allowed. */ | |
79 | static int audit_backlog_limit = 64; | |
80 | static atomic_t audit_backlog = ATOMIC_INIT(0); | |
81 | ||
82 | /* Records can be lost in several ways: | |
83 | 0) [suppressed in audit_alloc] | |
84 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] | |
85 | 2) out of memory in audit_log_move [alloc_skb] | |
86 | 3) suppressed due to audit_rate_limit | |
87 | 4) suppressed due to audit_backlog_limit | |
88 | */ | |
89 | static atomic_t audit_lost = ATOMIC_INIT(0); | |
90 | ||
91 | /* The netlink socket. */ | |
92 | static struct sock *audit_sock; | |
93 | ||
94 | /* There are two lists of audit buffers. The txlist contains audit | |
95 | * buffers that cannot be sent immediately to the netlink device because | |
96 | * we are in an irq context (these are sent later in a tasklet). | |
97 | * | |
98 | * The second list is a list of pre-allocated audit buffers (if more | |
99 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of | |
100 | * being placed on the freelist). */ | |
101 | static DEFINE_SPINLOCK(audit_txlist_lock); | |
102 | static DEFINE_SPINLOCK(audit_freelist_lock); | |
103 | static int audit_freelist_count = 0; | |
104 | static LIST_HEAD(audit_txlist); | |
105 | static LIST_HEAD(audit_freelist); | |
106 | ||
107 | /* There are three lists of rules -- one to search at task creation | |
108 | * time, one to search at syscall entry time, and another to search at | |
109 | * syscall exit time. */ | |
110 | static LIST_HEAD(audit_tsklist); | |
111 | static LIST_HEAD(audit_entlist); | |
112 | static LIST_HEAD(audit_extlist); | |
113 | ||
114 | /* The netlink socket is only to be read by 1 CPU, which lets us assume | |
115 | * that list additions and deletions never happen simultaneiously in | |
116 | * auditsc.c */ | |
117 | static DECLARE_MUTEX(audit_netlink_sem); | |
118 | ||
119 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
120 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
121 | * should be at least that large. */ | |
122 | #define AUDIT_BUFSIZ 1024 | |
123 | ||
124 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
125 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
126 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
127 | ||
128 | /* The audit_buffer is used when formatting an audit record. The caller | |
129 | * locks briefly to get the record off the freelist or to allocate the | |
130 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
131 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
132 | * use simultaneously. */ | |
133 | struct audit_buffer { | |
134 | struct list_head list; | |
135 | struct sk_buff_head sklist; /* formatted skbs ready to send */ | |
136 | struct audit_context *ctx; /* NULL or associated context */ | |
137 | int len; /* used area of tmp */ | |
138 | char tmp[AUDIT_BUFSIZ]; | |
139 | ||
140 | /* Pointer to header and contents */ | |
141 | struct nlmsghdr *nlh; | |
142 | int total; | |
143 | int type; | |
144 | int pid; | |
1da177e4 LT |
145 | }; |
146 | ||
147 | void audit_set_type(struct audit_buffer *ab, int type) | |
148 | { | |
149 | ab->type = type; | |
150 | } | |
151 | ||
152 | struct audit_entry { | |
153 | struct list_head list; | |
154 | struct audit_rule rule; | |
155 | }; | |
156 | ||
157 | static void audit_log_end_irq(struct audit_buffer *ab); | |
158 | static void audit_log_end_fast(struct audit_buffer *ab); | |
159 | ||
160 | static void audit_panic(const char *message) | |
161 | { | |
162 | switch (audit_failure) | |
163 | { | |
164 | case AUDIT_FAIL_SILENT: | |
165 | break; | |
166 | case AUDIT_FAIL_PRINTK: | |
167 | printk(KERN_ERR "audit: %s\n", message); | |
168 | break; | |
169 | case AUDIT_FAIL_PANIC: | |
170 | panic("audit: %s\n", message); | |
171 | break; | |
172 | } | |
173 | } | |
174 | ||
175 | static inline int audit_rate_check(void) | |
176 | { | |
177 | static unsigned long last_check = 0; | |
178 | static int messages = 0; | |
179 | static DEFINE_SPINLOCK(lock); | |
180 | unsigned long flags; | |
181 | unsigned long now; | |
182 | unsigned long elapsed; | |
183 | int retval = 0; | |
184 | ||
185 | if (!audit_rate_limit) return 1; | |
186 | ||
187 | spin_lock_irqsave(&lock, flags); | |
188 | if (++messages < audit_rate_limit) { | |
189 | retval = 1; | |
190 | } else { | |
191 | now = jiffies; | |
192 | elapsed = now - last_check; | |
193 | if (elapsed > HZ) { | |
194 | last_check = now; | |
195 | messages = 0; | |
196 | retval = 1; | |
197 | } | |
198 | } | |
199 | spin_unlock_irqrestore(&lock, flags); | |
200 | ||
201 | return retval; | |
202 | } | |
203 | ||
204 | /* Emit at least 1 message per second, even if audit_rate_check is | |
205 | * throttling. */ | |
206 | void audit_log_lost(const char *message) | |
207 | { | |
208 | static unsigned long last_msg = 0; | |
209 | static DEFINE_SPINLOCK(lock); | |
210 | unsigned long flags; | |
211 | unsigned long now; | |
212 | int print; | |
213 | ||
214 | atomic_inc(&audit_lost); | |
215 | ||
216 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
217 | ||
218 | if (!print) { | |
219 | spin_lock_irqsave(&lock, flags); | |
220 | now = jiffies; | |
221 | if (now - last_msg > HZ) { | |
222 | print = 1; | |
223 | last_msg = now; | |
224 | } | |
225 | spin_unlock_irqrestore(&lock, flags); | |
226 | } | |
227 | ||
228 | if (print) { | |
229 | printk(KERN_WARNING | |
230 | "audit: audit_lost=%d audit_backlog=%d" | |
231 | " audit_rate_limit=%d audit_backlog_limit=%d\n", | |
232 | atomic_read(&audit_lost), | |
233 | atomic_read(&audit_backlog), | |
234 | audit_rate_limit, | |
235 | audit_backlog_limit); | |
236 | audit_panic(message); | |
237 | } | |
238 | ||
239 | } | |
240 | ||
c94c257c | 241 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
242 | { |
243 | int old = audit_rate_limit; | |
244 | audit_rate_limit = limit; | |
c94c257c SH |
245 | audit_log(NULL, "audit_rate_limit=%d old=%d by auid %u", |
246 | audit_rate_limit, old, loginuid); | |
1da177e4 LT |
247 | return old; |
248 | } | |
249 | ||
c94c257c | 250 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
251 | { |
252 | int old = audit_backlog_limit; | |
253 | audit_backlog_limit = limit; | |
c94c257c SH |
254 | audit_log(NULL, "audit_backlog_limit=%d old=%d by auid %u", |
255 | audit_backlog_limit, old, loginuid); | |
1da177e4 LT |
256 | return old; |
257 | } | |
258 | ||
c94c257c | 259 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
260 | { |
261 | int old = audit_enabled; | |
262 | if (state != 0 && state != 1) | |
263 | return -EINVAL; | |
264 | audit_enabled = state; | |
c94c257c SH |
265 | audit_log(NULL, "audit_enabled=%d old=%d by auid %u", |
266 | audit_enabled, old, loginuid); | |
1da177e4 LT |
267 | return old; |
268 | } | |
269 | ||
c94c257c | 270 | static int audit_set_failure(int state, uid_t loginuid) |
1da177e4 LT |
271 | { |
272 | int old = audit_failure; | |
273 | if (state != AUDIT_FAIL_SILENT | |
274 | && state != AUDIT_FAIL_PRINTK | |
275 | && state != AUDIT_FAIL_PANIC) | |
276 | return -EINVAL; | |
277 | audit_failure = state; | |
c94c257c SH |
278 | audit_log(NULL, "audit_failure=%d old=%d by auid %u", |
279 | audit_failure, old, loginuid); | |
1da177e4 LT |
280 | return old; |
281 | } | |
282 | ||
283 | #ifdef CONFIG_NET | |
284 | void audit_send_reply(int pid, int seq, int type, int done, int multi, | |
285 | void *payload, int size) | |
286 | { | |
287 | struct sk_buff *skb; | |
288 | struct nlmsghdr *nlh; | |
289 | int len = NLMSG_SPACE(size); | |
290 | void *data; | |
291 | int flags = multi ? NLM_F_MULTI : 0; | |
292 | int t = done ? NLMSG_DONE : type; | |
293 | ||
294 | skb = alloc_skb(len, GFP_KERNEL); | |
295 | if (!skb) | |
296 | goto nlmsg_failure; | |
297 | ||
298 | nlh = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh)); | |
299 | nlh->nlmsg_flags = flags; | |
300 | data = NLMSG_DATA(nlh); | |
301 | memcpy(data, payload, size); | |
302 | netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT); | |
303 | return; | |
304 | ||
305 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
306 | if (skb) | |
307 | kfree_skb(skb); | |
308 | } | |
309 | ||
310 | /* | |
311 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
312 | * control messages. | |
313 | */ | |
314 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
315 | { | |
316 | int err = 0; | |
317 | ||
318 | switch (msg_type) { | |
319 | case AUDIT_GET: | |
320 | case AUDIT_LIST: | |
321 | case AUDIT_SET: | |
322 | case AUDIT_ADD: | |
323 | case AUDIT_DEL: | |
324 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) | |
325 | err = -EPERM; | |
326 | break; | |
327 | case AUDIT_USER: | |
328 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) | |
329 | err = -EPERM; | |
330 | break; | |
331 | default: /* bad msg */ | |
332 | err = -EINVAL; | |
333 | } | |
334 | ||
335 | return err; | |
336 | } | |
337 | ||
338 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
339 | { | |
340 | u32 uid, pid, seq; | |
341 | void *data; | |
342 | struct audit_status *status_get, status_set; | |
343 | int err; | |
344 | struct audit_buffer *ab; | |
345 | u16 msg_type = nlh->nlmsg_type; | |
c94c257c | 346 | uid_t loginuid; /* loginuid of sender */ |
1da177e4 LT |
347 | |
348 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
349 | if (err) | |
350 | return err; | |
351 | ||
352 | pid = NETLINK_CREDS(skb)->pid; | |
353 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 354 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
355 | seq = nlh->nlmsg_seq; |
356 | data = NLMSG_DATA(nlh); | |
357 | ||
358 | switch (msg_type) { | |
359 | case AUDIT_GET: | |
360 | status_set.enabled = audit_enabled; | |
361 | status_set.failure = audit_failure; | |
362 | status_set.pid = audit_pid; | |
363 | status_set.rate_limit = audit_rate_limit; | |
364 | status_set.backlog_limit = audit_backlog_limit; | |
365 | status_set.lost = atomic_read(&audit_lost); | |
366 | status_set.backlog = atomic_read(&audit_backlog); | |
367 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
368 | &status_set, sizeof(status_set)); | |
369 | break; | |
370 | case AUDIT_SET: | |
371 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
372 | return -EINVAL; | |
373 | status_get = (struct audit_status *)data; | |
374 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 375 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
376 | if (err < 0) return err; |
377 | } | |
378 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 379 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
380 | if (err < 0) return err; |
381 | } | |
382 | if (status_get->mask & AUDIT_STATUS_PID) { | |
383 | int old = audit_pid; | |
384 | audit_pid = status_get->pid; | |
c94c257c SH |
385 | audit_log(NULL, "audit_pid=%d old=%d by auid %u", |
386 | audit_pid, old, loginuid); | |
1da177e4 LT |
387 | } |
388 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 389 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 390 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
391 | audit_set_backlog_limit(status_get->backlog_limit, |
392 | loginuid); | |
1da177e4 LT |
393 | break; |
394 | case AUDIT_USER: | |
395 | ab = audit_log_start(NULL); | |
396 | if (!ab) | |
397 | break; /* audit_panic has been called */ | |
398 | audit_log_format(ab, | |
c94c257c SH |
399 | "user pid=%d uid=%d length=%d loginuid=%u" |
400 | " msg='%.1024s'", | |
1da177e4 LT |
401 | pid, uid, |
402 | (int)(nlh->nlmsg_len | |
403 | - ((char *)data - (char *)nlh)), | |
c94c257c | 404 | loginuid, (char *)data); |
1da177e4 LT |
405 | ab->type = AUDIT_USER; |
406 | ab->pid = pid; | |
407 | audit_log_end(ab); | |
408 | break; | |
409 | case AUDIT_ADD: | |
410 | case AUDIT_DEL: | |
411 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
412 | return -EINVAL; | |
413 | /* fallthrough */ | |
414 | case AUDIT_LIST: | |
415 | #ifdef CONFIG_AUDITSYSCALL | |
416 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, | |
c94c257c | 417 | uid, seq, data, loginuid); |
1da177e4 LT |
418 | #else |
419 | err = -EOPNOTSUPP; | |
420 | #endif | |
421 | break; | |
422 | default: | |
423 | err = -EINVAL; | |
424 | break; | |
425 | } | |
426 | ||
427 | return err < 0 ? err : 0; | |
428 | } | |
429 | ||
430 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
431 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
432 | * discarded silently. */ | |
2a0a6ebe | 433 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
434 | { |
435 | int err; | |
436 | struct nlmsghdr *nlh; | |
437 | u32 rlen; | |
438 | ||
439 | while (skb->len >= NLMSG_SPACE(0)) { | |
440 | nlh = (struct nlmsghdr *)skb->data; | |
441 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 442 | return; |
1da177e4 LT |
443 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
444 | if (rlen > skb->len) | |
445 | rlen = skb->len; | |
446 | if ((err = audit_receive_msg(skb, nlh))) { | |
447 | netlink_ack(skb, nlh, err); | |
448 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
449 | netlink_ack(skb, nlh, 0); | |
450 | skb_pull(skb, rlen); | |
451 | } | |
1da177e4 LT |
452 | } |
453 | ||
454 | /* Receive messages from netlink socket. */ | |
455 | static void audit_receive(struct sock *sk, int length) | |
456 | { | |
457 | struct sk_buff *skb; | |
2a0a6ebe | 458 | unsigned int qlen; |
1da177e4 | 459 | |
2a0a6ebe | 460 | down(&audit_netlink_sem); |
1da177e4 | 461 | |
2a0a6ebe HX |
462 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
463 | skb = skb_dequeue(&sk->sk_receive_queue); | |
464 | audit_receive_skb(skb); | |
465 | kfree_skb(skb); | |
1da177e4 LT |
466 | } |
467 | up(&audit_netlink_sem); | |
468 | } | |
469 | ||
470 | /* Move data from tmp buffer into an skb. This is an extra copy, and | |
471 | * that is unfortunate. However, the copy will only occur when a record | |
472 | * is being written to user space, which is already a high-overhead | |
473 | * operation. (Elimination of the copy is possible, for example, by | |
474 | * writing directly into a pre-allocated skb, at the cost of wasting | |
475 | * memory. */ | |
476 | static void audit_log_move(struct audit_buffer *ab) | |
477 | { | |
478 | struct sk_buff *skb; | |
479 | char *start; | |
480 | int extra = ab->nlh ? 0 : NLMSG_SPACE(0); | |
481 | ||
482 | /* possible resubmission */ | |
483 | if (ab->len == 0) | |
484 | return; | |
485 | ||
0dd8e06b | 486 | skb = skb_peek_tail(&ab->sklist); |
1da177e4 LT |
487 | if (!skb || skb_tailroom(skb) <= ab->len + extra) { |
488 | skb = alloc_skb(2 * ab->len + extra, GFP_ATOMIC); | |
489 | if (!skb) { | |
490 | ab->len = 0; /* Lose information in ab->tmp */ | |
491 | audit_log_lost("out of memory in audit_log_move"); | |
492 | return; | |
493 | } | |
494 | __skb_queue_tail(&ab->sklist, skb); | |
495 | if (!ab->nlh) | |
496 | ab->nlh = (struct nlmsghdr *)skb_put(skb, | |
497 | NLMSG_SPACE(0)); | |
498 | } | |
499 | start = skb_put(skb, ab->len); | |
500 | memcpy(start, ab->tmp, ab->len); | |
501 | ab->len = 0; | |
502 | } | |
503 | ||
504 | /* Iterate over the skbuff in the audit_buffer, sending their contents | |
505 | * to user space. */ | |
506 | static inline int audit_log_drain(struct audit_buffer *ab) | |
507 | { | |
508 | struct sk_buff *skb; | |
509 | ||
510 | while ((skb = skb_dequeue(&ab->sklist))) { | |
511 | int retval = 0; | |
512 | ||
513 | if (audit_pid) { | |
514 | if (ab->nlh) { | |
515 | ab->nlh->nlmsg_len = ab->total; | |
516 | ab->nlh->nlmsg_type = ab->type; | |
517 | ab->nlh->nlmsg_flags = 0; | |
518 | ab->nlh->nlmsg_seq = 0; | |
519 | ab->nlh->nlmsg_pid = ab->pid; | |
520 | } | |
521 | skb_get(skb); /* because netlink_* frees */ | |
522 | retval = netlink_unicast(audit_sock, skb, audit_pid, | |
523 | MSG_DONTWAIT); | |
524 | } | |
37509e74 CW |
525 | if (retval == -EAGAIN && |
526 | (atomic_read(&audit_backlog)) < audit_backlog_limit) { | |
527 | skb_queue_head(&ab->sklist, skb); | |
1da177e4 LT |
528 | audit_log_end_irq(ab); |
529 | return 1; | |
530 | } | |
531 | if (retval < 0) { | |
532 | if (retval == -ECONNREFUSED) { | |
533 | printk(KERN_ERR | |
534 | "audit: *NO* daemon at audit_pid=%d\n", | |
535 | audit_pid); | |
536 | audit_pid = 0; | |
537 | } else | |
538 | audit_log_lost("netlink socket too busy"); | |
539 | } | |
540 | if (!audit_pid) { /* No daemon */ | |
541 | int offset = ab->nlh ? NLMSG_SPACE(0) : 0; | |
542 | int len = skb->len - offset; | |
c7fcb0ee PM |
543 | skb->data[offset + len] = '\0'; |
544 | printk(KERN_ERR "%s\n", skb->data + offset); | |
1da177e4 LT |
545 | } |
546 | kfree_skb(skb); | |
547 | ab->nlh = NULL; | |
548 | } | |
549 | return 0; | |
550 | } | |
551 | ||
552 | /* Initialize audit support at boot time. */ | |
553 | static int __init audit_init(void) | |
554 | { | |
555 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
556 | audit_default ? "enabled" : "disabled"); | |
557 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
558 | if (!audit_sock) | |
559 | audit_panic("cannot initialize netlink socket"); | |
560 | ||
561 | audit_initialized = 1; | |
562 | audit_enabled = audit_default; | |
563 | audit_log(NULL, "initialized"); | |
564 | return 0; | |
565 | } | |
566 | ||
567 | #else | |
568 | /* Without CONFIG_NET, we have no skbuffs. For now, print what we have | |
569 | * in the buffer. */ | |
570 | static void audit_log_move(struct audit_buffer *ab) | |
571 | { | |
572 | printk(KERN_ERR "%*.*s\n", ab->len, ab->len, ab->tmp); | |
573 | ab->len = 0; | |
574 | } | |
575 | ||
576 | static inline int audit_log_drain(struct audit_buffer *ab) | |
577 | { | |
578 | return 0; | |
579 | } | |
580 | ||
581 | /* Initialize audit support at boot time. */ | |
582 | int __init audit_init(void) | |
583 | { | |
584 | printk(KERN_INFO "audit: initializing WITHOUT netlink support\n"); | |
585 | audit_sock = NULL; | |
586 | audit_pid = 0; | |
587 | ||
588 | audit_initialized = 1; | |
589 | audit_enabled = audit_default; | |
590 | audit_log(NULL, "initialized"); | |
591 | return 0; | |
592 | } | |
593 | #endif | |
594 | ||
595 | __initcall(audit_init); | |
596 | ||
597 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
598 | static int __init audit_enable(char *str) | |
599 | { | |
600 | audit_default = !!simple_strtol(str, NULL, 0); | |
601 | printk(KERN_INFO "audit: %s%s\n", | |
602 | audit_default ? "enabled" : "disabled", | |
603 | audit_initialized ? "" : " (after initialization)"); | |
604 | if (audit_initialized) | |
605 | audit_enabled = audit_default; | |
606 | return 0; | |
607 | } | |
608 | ||
609 | __setup("audit=", audit_enable); | |
610 | ||
611 | ||
612 | /* Obtain an audit buffer. This routine does locking to obtain the | |
613 | * audit buffer, but then no locking is required for calls to | |
614 | * audit_log_*format. If the tsk is a task that is currently in a | |
615 | * syscall, then the syscall is marked as auditable and an audit record | |
616 | * will be written at syscall exit. If there is no associated task, tsk | |
617 | * should be NULL. */ | |
618 | struct audit_buffer *audit_log_start(struct audit_context *ctx) | |
619 | { | |
620 | struct audit_buffer *ab = NULL; | |
621 | unsigned long flags; | |
622 | struct timespec t; | |
d812ddbb | 623 | unsigned int serial; |
1da177e4 LT |
624 | |
625 | if (!audit_initialized) | |
626 | return NULL; | |
627 | ||
628 | if (audit_backlog_limit | |
629 | && atomic_read(&audit_backlog) > audit_backlog_limit) { | |
630 | if (audit_rate_check()) | |
631 | printk(KERN_WARNING | |
632 | "audit: audit_backlog=%d > " | |
633 | "audit_backlog_limit=%d\n", | |
634 | atomic_read(&audit_backlog), | |
635 | audit_backlog_limit); | |
636 | audit_log_lost("backlog limit exceeded"); | |
637 | return NULL; | |
638 | } | |
639 | ||
640 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
641 | if (!list_empty(&audit_freelist)) { | |
642 | ab = list_entry(audit_freelist.next, | |
643 | struct audit_buffer, list); | |
644 | list_del(&ab->list); | |
645 | --audit_freelist_count; | |
646 | } | |
647 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
648 | ||
649 | if (!ab) | |
650 | ab = kmalloc(sizeof(*ab), GFP_ATOMIC); | |
651 | if (!ab) { | |
652 | audit_log_lost("out of memory in audit_log_start"); | |
653 | return NULL; | |
654 | } | |
655 | ||
656 | atomic_inc(&audit_backlog); | |
657 | skb_queue_head_init(&ab->sklist); | |
658 | ||
659 | ab->ctx = ctx; | |
660 | ab->len = 0; | |
661 | ab->nlh = NULL; | |
662 | ab->total = 0; | |
663 | ab->type = AUDIT_KERNEL; | |
664 | ab->pid = 0; | |
1da177e4 LT |
665 | |
666 | #ifdef CONFIG_AUDITSYSCALL | |
667 | if (ab->ctx) | |
668 | audit_get_stamp(ab->ctx, &t, &serial); | |
669 | else | |
670 | #endif | |
d812ddbb | 671 | { |
1da177e4 | 672 | t = CURRENT_TIME; |
d812ddbb SG |
673 | serial = 0; |
674 | } | |
1da177e4 LT |
675 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
676 | t.tv_sec, t.tv_nsec/1000000, serial); | |
677 | return ab; | |
678 | } | |
679 | ||
680 | ||
681 | /* Format an audit message into the audit buffer. If there isn't enough | |
682 | * room in the audit buffer, more room will be allocated and vsnprint | |
683 | * will be called a second time. Currently, we assume that a printk | |
684 | * can't format message larger than 1024 bytes, so we don't either. */ | |
685 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
686 | va_list args) | |
687 | { | |
688 | int len, avail; | |
689 | ||
690 | if (!ab) | |
691 | return; | |
692 | ||
693 | avail = sizeof(ab->tmp) - ab->len; | |
694 | if (avail <= 0) { | |
695 | audit_log_move(ab); | |
696 | avail = sizeof(ab->tmp) - ab->len; | |
697 | } | |
698 | len = vsnprintf(ab->tmp + ab->len, avail, fmt, args); | |
699 | if (len >= avail) { | |
700 | /* The printk buffer is 1024 bytes long, so if we get | |
701 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
702 | * log everything that printk could have logged. */ | |
703 | audit_log_move(ab); | |
704 | avail = sizeof(ab->tmp) - ab->len; | |
705 | len = vsnprintf(ab->tmp + ab->len, avail, fmt, args); | |
706 | } | |
707 | ab->len += (len < avail) ? len : avail; | |
708 | ab->total += (len < avail) ? len : avail; | |
709 | } | |
710 | ||
711 | /* Format a message into the audit buffer. All the work is done in | |
712 | * audit_log_vformat. */ | |
713 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
714 | { | |
715 | va_list args; | |
716 | ||
717 | if (!ab) | |
718 | return; | |
719 | va_start(args, fmt); | |
720 | audit_log_vformat(ab, fmt, args); | |
721 | va_end(args); | |
722 | } | |
723 | ||
83c7d091 | 724 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len) |
725 | { | |
726 | int i; | |
727 | ||
728 | for (i=0; i<len; i++) | |
729 | audit_log_format(ab, "%02x", buf[i]); | |
730 | } | |
731 | ||
732 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) | |
733 | { | |
81b7854d | 734 | const unsigned char *p = string; |
83c7d091 | 735 | |
736 | while (*p) { | |
737 | if (*p == '"' || *p == ' ' || *p < 0x20 || *p > 0x7f) { | |
738 | audit_log_hex(ab, string, strlen(string)); | |
739 | return; | |
740 | } | |
741 | p++; | |
742 | } | |
743 | audit_log_format(ab, "\"%s\"", string); | |
744 | } | |
745 | ||
746 | ||
1da177e4 LT |
747 | /* This is a helper-function to print the d_path without using a static |
748 | * buffer or allocating another buffer in addition to the one in | |
749 | * audit_buffer. */ | |
750 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
751 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
752 | { | |
753 | char *p; | |
754 | int len, avail; | |
755 | ||
756 | if (prefix) audit_log_format(ab, " %s", prefix); | |
757 | ||
758 | if (ab->len > 128) | |
759 | audit_log_move(ab); | |
760 | avail = sizeof(ab->tmp) - ab->len; | |
761 | p = d_path(dentry, vfsmnt, ab->tmp + ab->len, avail); | |
762 | if (IS_ERR(p)) { | |
763 | /* FIXME: can we save some information here? */ | |
764 | audit_log_format(ab, "<toolong>"); | |
765 | } else { | |
766 | /* path isn't at start of buffer */ | |
767 | len = (ab->tmp + sizeof(ab->tmp) - 1) - p; | |
768 | memmove(ab->tmp + ab->len, p, len); | |
769 | ab->len += len; | |
770 | ab->total += len; | |
771 | } | |
772 | } | |
773 | ||
774 | /* Remove queued messages from the audit_txlist and send them to userspace. */ | |
775 | static void audit_tasklet_handler(unsigned long arg) | |
776 | { | |
777 | LIST_HEAD(list); | |
778 | struct audit_buffer *ab; | |
779 | unsigned long flags; | |
780 | ||
781 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
782 | list_splice_init(&audit_txlist, &list); | |
783 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
784 | ||
785 | while (!list_empty(&list)) { | |
786 | ab = list_entry(list.next, struct audit_buffer, list); | |
787 | list_del(&ab->list); | |
788 | audit_log_end_fast(ab); | |
789 | } | |
790 | } | |
791 | ||
792 | static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0); | |
793 | ||
794 | /* The netlink_* functions cannot be called inside an irq context, so | |
795 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
796 | * remove them from the queue outside the irq context. May be called in | |
797 | * any context. */ | |
798 | static void audit_log_end_irq(struct audit_buffer *ab) | |
799 | { | |
800 | unsigned long flags; | |
801 | ||
802 | if (!ab) | |
803 | return; | |
804 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
805 | list_add_tail(&ab->list, &audit_txlist); | |
806 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
807 | ||
808 | tasklet_schedule(&audit_tasklet); | |
809 | } | |
810 | ||
811 | /* Send the message in the audit buffer directly to user space. May not | |
812 | * be called in an irq context. */ | |
813 | static void audit_log_end_fast(struct audit_buffer *ab) | |
814 | { | |
815 | unsigned long flags; | |
816 | ||
817 | BUG_ON(in_irq()); | |
818 | if (!ab) | |
819 | return; | |
820 | if (!audit_rate_check()) { | |
821 | audit_log_lost("rate limit exceeded"); | |
822 | } else { | |
823 | audit_log_move(ab); | |
824 | if (audit_log_drain(ab)) | |
825 | return; | |
826 | } | |
827 | ||
828 | atomic_dec(&audit_backlog); | |
829 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
830 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
831 | kfree(ab); | |
832 | else | |
833 | list_add(&ab->list, &audit_freelist); | |
834 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
835 | } | |
836 | ||
837 | /* Send or queue the message in the audit buffer, depending on the | |
838 | * current context. (A convenience function that may be called in any | |
839 | * context.) */ | |
840 | void audit_log_end(struct audit_buffer *ab) | |
841 | { | |
842 | if (in_irq()) | |
843 | audit_log_end_irq(ab); | |
844 | else | |
845 | audit_log_end_fast(ab); | |
846 | } | |
847 | ||
848 | /* Log an audit record. This is a convenience function that calls | |
849 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
850 | * called in any context. */ | |
851 | void audit_log(struct audit_context *ctx, const char *fmt, ...) | |
852 | { | |
853 | struct audit_buffer *ab; | |
854 | va_list args; | |
855 | ||
856 | ab = audit_log_start(ctx); | |
857 | if (ab) { | |
858 | va_start(args, fmt); | |
859 | audit_log_vformat(ab, fmt, args); | |
860 | va_end(args); | |
861 | audit_log_end(ab); | |
862 | } | |
863 | } |