]>
Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* audit.c -- Auditing support -*- linux-c -*- |
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 | * | |
41 | * Example user-space utilities: http://people.redhat.com/faith/audit/ | |
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; | |
145 | int count; /* Times requeued */ | |
146 | }; | |
147 | ||
148 | void audit_set_type(struct audit_buffer *ab, int type) | |
149 | { | |
150 | ab->type = type; | |
151 | } | |
152 | ||
153 | struct audit_entry { | |
154 | struct list_head list; | |
155 | struct audit_rule rule; | |
156 | }; | |
157 | ||
158 | static void audit_log_end_irq(struct audit_buffer *ab); | |
159 | static void audit_log_end_fast(struct audit_buffer *ab); | |
160 | ||
161 | static void audit_panic(const char *message) | |
162 | { | |
163 | switch (audit_failure) | |
164 | { | |
165 | case AUDIT_FAIL_SILENT: | |
166 | break; | |
167 | case AUDIT_FAIL_PRINTK: | |
168 | printk(KERN_ERR "audit: %s\n", message); | |
169 | break; | |
170 | case AUDIT_FAIL_PANIC: | |
171 | panic("audit: %s\n", message); | |
172 | break; | |
173 | } | |
174 | } | |
175 | ||
176 | static inline int audit_rate_check(void) | |
177 | { | |
178 | static unsigned long last_check = 0; | |
179 | static int messages = 0; | |
180 | static DEFINE_SPINLOCK(lock); | |
181 | unsigned long flags; | |
182 | unsigned long now; | |
183 | unsigned long elapsed; | |
184 | int retval = 0; | |
185 | ||
186 | if (!audit_rate_limit) return 1; | |
187 | ||
188 | spin_lock_irqsave(&lock, flags); | |
189 | if (++messages < audit_rate_limit) { | |
190 | retval = 1; | |
191 | } else { | |
192 | now = jiffies; | |
193 | elapsed = now - last_check; | |
194 | if (elapsed > HZ) { | |
195 | last_check = now; | |
196 | messages = 0; | |
197 | retval = 1; | |
198 | } | |
199 | } | |
200 | spin_unlock_irqrestore(&lock, flags); | |
201 | ||
202 | return retval; | |
203 | } | |
204 | ||
205 | /* Emit at least 1 message per second, even if audit_rate_check is | |
206 | * throttling. */ | |
207 | void audit_log_lost(const char *message) | |
208 | { | |
209 | static unsigned long last_msg = 0; | |
210 | static DEFINE_SPINLOCK(lock); | |
211 | unsigned long flags; | |
212 | unsigned long now; | |
213 | int print; | |
214 | ||
215 | atomic_inc(&audit_lost); | |
216 | ||
217 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
218 | ||
219 | if (!print) { | |
220 | spin_lock_irqsave(&lock, flags); | |
221 | now = jiffies; | |
222 | if (now - last_msg > HZ) { | |
223 | print = 1; | |
224 | last_msg = now; | |
225 | } | |
226 | spin_unlock_irqrestore(&lock, flags); | |
227 | } | |
228 | ||
229 | if (print) { | |
230 | printk(KERN_WARNING | |
231 | "audit: audit_lost=%d audit_backlog=%d" | |
232 | " audit_rate_limit=%d audit_backlog_limit=%d\n", | |
233 | atomic_read(&audit_lost), | |
234 | atomic_read(&audit_backlog), | |
235 | audit_rate_limit, | |
236 | audit_backlog_limit); | |
237 | audit_panic(message); | |
238 | } | |
239 | ||
240 | } | |
241 | ||
242 | static int audit_set_rate_limit(int limit) | |
243 | { | |
244 | int old = audit_rate_limit; | |
245 | audit_rate_limit = limit; | |
246 | audit_log(current->audit_context, "audit_rate_limit=%d old=%d", | |
247 | audit_rate_limit, old); | |
248 | return old; | |
249 | } | |
250 | ||
251 | static int audit_set_backlog_limit(int limit) | |
252 | { | |
253 | int old = audit_backlog_limit; | |
254 | audit_backlog_limit = limit; | |
255 | audit_log(current->audit_context, "audit_backlog_limit=%d old=%d", | |
256 | audit_backlog_limit, old); | |
257 | return old; | |
258 | } | |
259 | ||
260 | static int audit_set_enabled(int state) | |
261 | { | |
262 | int old = audit_enabled; | |
263 | if (state != 0 && state != 1) | |
264 | return -EINVAL; | |
265 | audit_enabled = state; | |
266 | audit_log(current->audit_context, "audit_enabled=%d old=%d", | |
267 | audit_enabled, old); | |
268 | return old; | |
269 | } | |
270 | ||
271 | static int audit_set_failure(int state) | |
272 | { | |
273 | int old = audit_failure; | |
274 | if (state != AUDIT_FAIL_SILENT | |
275 | && state != AUDIT_FAIL_PRINTK | |
276 | && state != AUDIT_FAIL_PANIC) | |
277 | return -EINVAL; | |
278 | audit_failure = state; | |
279 | audit_log(current->audit_context, "audit_failure=%d old=%d", | |
280 | audit_failure, old); | |
281 | return old; | |
282 | } | |
283 | ||
284 | #ifdef CONFIG_NET | |
285 | void audit_send_reply(int pid, int seq, int type, int done, int multi, | |
286 | void *payload, int size) | |
287 | { | |
288 | struct sk_buff *skb; | |
289 | struct nlmsghdr *nlh; | |
290 | int len = NLMSG_SPACE(size); | |
291 | void *data; | |
292 | int flags = multi ? NLM_F_MULTI : 0; | |
293 | int t = done ? NLMSG_DONE : type; | |
294 | ||
295 | skb = alloc_skb(len, GFP_KERNEL); | |
296 | if (!skb) | |
297 | goto nlmsg_failure; | |
298 | ||
299 | nlh = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh)); | |
300 | nlh->nlmsg_flags = flags; | |
301 | data = NLMSG_DATA(nlh); | |
302 | memcpy(data, payload, size); | |
303 | netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT); | |
304 | return; | |
305 | ||
306 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
307 | if (skb) | |
308 | kfree_skb(skb); | |
309 | } | |
310 | ||
311 | /* | |
312 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
313 | * control messages. | |
314 | */ | |
315 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
316 | { | |
317 | int err = 0; | |
318 | ||
319 | switch (msg_type) { | |
320 | case AUDIT_GET: | |
321 | case AUDIT_LIST: | |
322 | case AUDIT_SET: | |
323 | case AUDIT_ADD: | |
324 | case AUDIT_DEL: | |
325 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) | |
326 | err = -EPERM; | |
327 | break; | |
328 | case AUDIT_USER: | |
329 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) | |
330 | err = -EPERM; | |
331 | break; | |
332 | default: /* bad msg */ | |
333 | err = -EINVAL; | |
334 | } | |
335 | ||
336 | return err; | |
337 | } | |
338 | ||
339 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
340 | { | |
341 | u32 uid, pid, seq; | |
342 | void *data; | |
343 | struct audit_status *status_get, status_set; | |
344 | int err; | |
345 | struct audit_buffer *ab; | |
346 | u16 msg_type = nlh->nlmsg_type; | |
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; | |
354 | seq = nlh->nlmsg_seq; | |
355 | data = NLMSG_DATA(nlh); | |
356 | ||
357 | switch (msg_type) { | |
358 | case AUDIT_GET: | |
359 | status_set.enabled = audit_enabled; | |
360 | status_set.failure = audit_failure; | |
361 | status_set.pid = audit_pid; | |
362 | status_set.rate_limit = audit_rate_limit; | |
363 | status_set.backlog_limit = audit_backlog_limit; | |
364 | status_set.lost = atomic_read(&audit_lost); | |
365 | status_set.backlog = atomic_read(&audit_backlog); | |
366 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
367 | &status_set, sizeof(status_set)); | |
368 | break; | |
369 | case AUDIT_SET: | |
370 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
371 | return -EINVAL; | |
372 | status_get = (struct audit_status *)data; | |
373 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
374 | err = audit_set_enabled(status_get->enabled); | |
375 | if (err < 0) return err; | |
376 | } | |
377 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
378 | err = audit_set_failure(status_get->failure); | |
379 | if (err < 0) return err; | |
380 | } | |
381 | if (status_get->mask & AUDIT_STATUS_PID) { | |
382 | int old = audit_pid; | |
383 | audit_pid = status_get->pid; | |
384 | audit_log(current->audit_context, | |
385 | "audit_pid=%d old=%d", audit_pid, old); | |
386 | } | |
387 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
388 | audit_set_rate_limit(status_get->rate_limit); | |
389 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) | |
390 | audit_set_backlog_limit(status_get->backlog_limit); | |
391 | break; | |
392 | case AUDIT_USER: | |
393 | ab = audit_log_start(NULL); | |
394 | if (!ab) | |
395 | break; /* audit_panic has been called */ | |
396 | audit_log_format(ab, | |
397 | "user pid=%d uid=%d length=%d msg='%.1024s'", | |
398 | pid, uid, | |
399 | (int)(nlh->nlmsg_len | |
400 | - ((char *)data - (char *)nlh)), | |
401 | (char *)data); | |
402 | ab->type = AUDIT_USER; | |
403 | ab->pid = pid; | |
404 | audit_log_end(ab); | |
405 | break; | |
406 | case AUDIT_ADD: | |
407 | case AUDIT_DEL: | |
408 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
409 | return -EINVAL; | |
410 | /* fallthrough */ | |
411 | case AUDIT_LIST: | |
412 | #ifdef CONFIG_AUDITSYSCALL | |
413 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, | |
414 | uid, seq, data); | |
415 | #else | |
416 | err = -EOPNOTSUPP; | |
417 | #endif | |
418 | break; | |
419 | default: | |
420 | err = -EINVAL; | |
421 | break; | |
422 | } | |
423 | ||
424 | return err < 0 ? err : 0; | |
425 | } | |
426 | ||
427 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
428 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
429 | * discarded silently. */ | |
2a0a6ebe | 430 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
431 | { |
432 | int err; | |
433 | struct nlmsghdr *nlh; | |
434 | u32 rlen; | |
435 | ||
436 | while (skb->len >= NLMSG_SPACE(0)) { | |
437 | nlh = (struct nlmsghdr *)skb->data; | |
438 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 439 | return; |
1da177e4 LT |
440 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
441 | if (rlen > skb->len) | |
442 | rlen = skb->len; | |
443 | if ((err = audit_receive_msg(skb, nlh))) { | |
444 | netlink_ack(skb, nlh, err); | |
445 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
446 | netlink_ack(skb, nlh, 0); | |
447 | skb_pull(skb, rlen); | |
448 | } | |
1da177e4 LT |
449 | } |
450 | ||
451 | /* Receive messages from netlink socket. */ | |
452 | static void audit_receive(struct sock *sk, int length) | |
453 | { | |
454 | struct sk_buff *skb; | |
2a0a6ebe | 455 | unsigned int qlen; |
1da177e4 | 456 | |
2a0a6ebe | 457 | down(&audit_netlink_sem); |
1da177e4 | 458 | |
2a0a6ebe HX |
459 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
460 | skb = skb_dequeue(&sk->sk_receive_queue); | |
461 | audit_receive_skb(skb); | |
462 | kfree_skb(skb); | |
1da177e4 LT |
463 | } |
464 | up(&audit_netlink_sem); | |
465 | } | |
466 | ||
467 | /* Move data from tmp buffer into an skb. This is an extra copy, and | |
468 | * that is unfortunate. However, the copy will only occur when a record | |
469 | * is being written to user space, which is already a high-overhead | |
470 | * operation. (Elimination of the copy is possible, for example, by | |
471 | * writing directly into a pre-allocated skb, at the cost of wasting | |
472 | * memory. */ | |
473 | static void audit_log_move(struct audit_buffer *ab) | |
474 | { | |
475 | struct sk_buff *skb; | |
476 | char *start; | |
477 | int extra = ab->nlh ? 0 : NLMSG_SPACE(0); | |
478 | ||
479 | /* possible resubmission */ | |
480 | if (ab->len == 0) | |
481 | return; | |
482 | ||
483 | skb = skb_peek(&ab->sklist); | |
484 | if (!skb || skb_tailroom(skb) <= ab->len + extra) { | |
485 | skb = alloc_skb(2 * ab->len + extra, GFP_ATOMIC); | |
486 | if (!skb) { | |
487 | ab->len = 0; /* Lose information in ab->tmp */ | |
488 | audit_log_lost("out of memory in audit_log_move"); | |
489 | return; | |
490 | } | |
491 | __skb_queue_tail(&ab->sklist, skb); | |
492 | if (!ab->nlh) | |
493 | ab->nlh = (struct nlmsghdr *)skb_put(skb, | |
494 | NLMSG_SPACE(0)); | |
495 | } | |
496 | start = skb_put(skb, ab->len); | |
497 | memcpy(start, ab->tmp, ab->len); | |
498 | ab->len = 0; | |
499 | } | |
500 | ||
501 | /* Iterate over the skbuff in the audit_buffer, sending their contents | |
502 | * to user space. */ | |
503 | static inline int audit_log_drain(struct audit_buffer *ab) | |
504 | { | |
505 | struct sk_buff *skb; | |
506 | ||
507 | while ((skb = skb_dequeue(&ab->sklist))) { | |
508 | int retval = 0; | |
509 | ||
510 | if (audit_pid) { | |
511 | if (ab->nlh) { | |
512 | ab->nlh->nlmsg_len = ab->total; | |
513 | ab->nlh->nlmsg_type = ab->type; | |
514 | ab->nlh->nlmsg_flags = 0; | |
515 | ab->nlh->nlmsg_seq = 0; | |
516 | ab->nlh->nlmsg_pid = ab->pid; | |
517 | } | |
518 | skb_get(skb); /* because netlink_* frees */ | |
519 | retval = netlink_unicast(audit_sock, skb, audit_pid, | |
520 | MSG_DONTWAIT); | |
521 | } | |
522 | if (retval == -EAGAIN && ab->count < 5) { | |
523 | ++ab->count; | |
524 | skb_queue_tail(&ab->sklist, skb); | |
525 | audit_log_end_irq(ab); | |
526 | return 1; | |
527 | } | |
528 | if (retval < 0) { | |
529 | if (retval == -ECONNREFUSED) { | |
530 | printk(KERN_ERR | |
531 | "audit: *NO* daemon at audit_pid=%d\n", | |
532 | audit_pid); | |
533 | audit_pid = 0; | |
534 | } else | |
535 | audit_log_lost("netlink socket too busy"); | |
536 | } | |
537 | if (!audit_pid) { /* No daemon */ | |
538 | int offset = ab->nlh ? NLMSG_SPACE(0) : 0; | |
539 | int len = skb->len - offset; | |
540 | printk(KERN_ERR "%*.*s\n", | |
541 | len, len, skb->data + offset); | |
542 | } | |
543 | kfree_skb(skb); | |
544 | ab->nlh = NULL; | |
545 | } | |
546 | return 0; | |
547 | } | |
548 | ||
549 | /* Initialize audit support at boot time. */ | |
550 | static int __init audit_init(void) | |
551 | { | |
552 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
553 | audit_default ? "enabled" : "disabled"); | |
554 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
555 | if (!audit_sock) | |
556 | audit_panic("cannot initialize netlink socket"); | |
557 | ||
558 | audit_initialized = 1; | |
559 | audit_enabled = audit_default; | |
560 | audit_log(NULL, "initialized"); | |
561 | return 0; | |
562 | } | |
563 | ||
564 | #else | |
565 | /* Without CONFIG_NET, we have no skbuffs. For now, print what we have | |
566 | * in the buffer. */ | |
567 | static void audit_log_move(struct audit_buffer *ab) | |
568 | { | |
569 | printk(KERN_ERR "%*.*s\n", ab->len, ab->len, ab->tmp); | |
570 | ab->len = 0; | |
571 | } | |
572 | ||
573 | static inline int audit_log_drain(struct audit_buffer *ab) | |
574 | { | |
575 | return 0; | |
576 | } | |
577 | ||
578 | /* Initialize audit support at boot time. */ | |
579 | int __init audit_init(void) | |
580 | { | |
581 | printk(KERN_INFO "audit: initializing WITHOUT netlink support\n"); | |
582 | audit_sock = NULL; | |
583 | audit_pid = 0; | |
584 | ||
585 | audit_initialized = 1; | |
586 | audit_enabled = audit_default; | |
587 | audit_log(NULL, "initialized"); | |
588 | return 0; | |
589 | } | |
590 | #endif | |
591 | ||
592 | __initcall(audit_init); | |
593 | ||
594 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
595 | static int __init audit_enable(char *str) | |
596 | { | |
597 | audit_default = !!simple_strtol(str, NULL, 0); | |
598 | printk(KERN_INFO "audit: %s%s\n", | |
599 | audit_default ? "enabled" : "disabled", | |
600 | audit_initialized ? "" : " (after initialization)"); | |
601 | if (audit_initialized) | |
602 | audit_enabled = audit_default; | |
603 | return 0; | |
604 | } | |
605 | ||
606 | __setup("audit=", audit_enable); | |
607 | ||
608 | ||
609 | /* Obtain an audit buffer. This routine does locking to obtain the | |
610 | * audit buffer, but then no locking is required for calls to | |
611 | * audit_log_*format. If the tsk is a task that is currently in a | |
612 | * syscall, then the syscall is marked as auditable and an audit record | |
613 | * will be written at syscall exit. If there is no associated task, tsk | |
614 | * should be NULL. */ | |
615 | struct audit_buffer *audit_log_start(struct audit_context *ctx) | |
616 | { | |
617 | struct audit_buffer *ab = NULL; | |
618 | unsigned long flags; | |
619 | struct timespec t; | |
620 | int serial = 0; | |
621 | ||
622 | if (!audit_initialized) | |
623 | return NULL; | |
624 | ||
625 | if (audit_backlog_limit | |
626 | && atomic_read(&audit_backlog) > audit_backlog_limit) { | |
627 | if (audit_rate_check()) | |
628 | printk(KERN_WARNING | |
629 | "audit: audit_backlog=%d > " | |
630 | "audit_backlog_limit=%d\n", | |
631 | atomic_read(&audit_backlog), | |
632 | audit_backlog_limit); | |
633 | audit_log_lost("backlog limit exceeded"); | |
634 | return NULL; | |
635 | } | |
636 | ||
637 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
638 | if (!list_empty(&audit_freelist)) { | |
639 | ab = list_entry(audit_freelist.next, | |
640 | struct audit_buffer, list); | |
641 | list_del(&ab->list); | |
642 | --audit_freelist_count; | |
643 | } | |
644 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
645 | ||
646 | if (!ab) | |
647 | ab = kmalloc(sizeof(*ab), GFP_ATOMIC); | |
648 | if (!ab) { | |
649 | audit_log_lost("out of memory in audit_log_start"); | |
650 | return NULL; | |
651 | } | |
652 | ||
653 | atomic_inc(&audit_backlog); | |
654 | skb_queue_head_init(&ab->sklist); | |
655 | ||
656 | ab->ctx = ctx; | |
657 | ab->len = 0; | |
658 | ab->nlh = NULL; | |
659 | ab->total = 0; | |
660 | ab->type = AUDIT_KERNEL; | |
661 | ab->pid = 0; | |
662 | ab->count = 0; | |
663 | ||
664 | #ifdef CONFIG_AUDITSYSCALL | |
665 | if (ab->ctx) | |
666 | audit_get_stamp(ab->ctx, &t, &serial); | |
667 | else | |
668 | #endif | |
669 | t = CURRENT_TIME; | |
670 | ||
671 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", | |
672 | t.tv_sec, t.tv_nsec/1000000, serial); | |
673 | return ab; | |
674 | } | |
675 | ||
676 | ||
677 | /* Format an audit message into the audit buffer. If there isn't enough | |
678 | * room in the audit buffer, more room will be allocated and vsnprint | |
679 | * will be called a second time. Currently, we assume that a printk | |
680 | * can't format message larger than 1024 bytes, so we don't either. */ | |
681 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
682 | va_list args) | |
683 | { | |
684 | int len, avail; | |
685 | ||
686 | if (!ab) | |
687 | return; | |
688 | ||
689 | avail = sizeof(ab->tmp) - ab->len; | |
690 | if (avail <= 0) { | |
691 | audit_log_move(ab); | |
692 | avail = sizeof(ab->tmp) - ab->len; | |
693 | } | |
694 | len = vsnprintf(ab->tmp + ab->len, avail, fmt, args); | |
695 | if (len >= avail) { | |
696 | /* The printk buffer is 1024 bytes long, so if we get | |
697 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
698 | * log everything that printk could have logged. */ | |
699 | audit_log_move(ab); | |
700 | avail = sizeof(ab->tmp) - ab->len; | |
701 | len = vsnprintf(ab->tmp + ab->len, avail, fmt, args); | |
702 | } | |
703 | ab->len += (len < avail) ? len : avail; | |
704 | ab->total += (len < avail) ? len : avail; | |
705 | } | |
706 | ||
707 | /* Format a message into the audit buffer. All the work is done in | |
708 | * audit_log_vformat. */ | |
709 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
710 | { | |
711 | va_list args; | |
712 | ||
713 | if (!ab) | |
714 | return; | |
715 | va_start(args, fmt); | |
716 | audit_log_vformat(ab, fmt, args); | |
717 | va_end(args); | |
718 | } | |
719 | ||
720 | /* This is a helper-function to print the d_path without using a static | |
721 | * buffer or allocating another buffer in addition to the one in | |
722 | * audit_buffer. */ | |
723 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
724 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
725 | { | |
726 | char *p; | |
727 | int len, avail; | |
728 | ||
729 | if (prefix) audit_log_format(ab, " %s", prefix); | |
730 | ||
731 | if (ab->len > 128) | |
732 | audit_log_move(ab); | |
733 | avail = sizeof(ab->tmp) - ab->len; | |
734 | p = d_path(dentry, vfsmnt, ab->tmp + ab->len, avail); | |
735 | if (IS_ERR(p)) { | |
736 | /* FIXME: can we save some information here? */ | |
737 | audit_log_format(ab, "<toolong>"); | |
738 | } else { | |
739 | /* path isn't at start of buffer */ | |
740 | len = (ab->tmp + sizeof(ab->tmp) - 1) - p; | |
741 | memmove(ab->tmp + ab->len, p, len); | |
742 | ab->len += len; | |
743 | ab->total += len; | |
744 | } | |
745 | } | |
746 | ||
747 | /* Remove queued messages from the audit_txlist and send them to userspace. */ | |
748 | static void audit_tasklet_handler(unsigned long arg) | |
749 | { | |
750 | LIST_HEAD(list); | |
751 | struct audit_buffer *ab; | |
752 | unsigned long flags; | |
753 | ||
754 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
755 | list_splice_init(&audit_txlist, &list); | |
756 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
757 | ||
758 | while (!list_empty(&list)) { | |
759 | ab = list_entry(list.next, struct audit_buffer, list); | |
760 | list_del(&ab->list); | |
761 | audit_log_end_fast(ab); | |
762 | } | |
763 | } | |
764 | ||
765 | static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0); | |
766 | ||
767 | /* The netlink_* functions cannot be called inside an irq context, so | |
768 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
769 | * remove them from the queue outside the irq context. May be called in | |
770 | * any context. */ | |
771 | static void audit_log_end_irq(struct audit_buffer *ab) | |
772 | { | |
773 | unsigned long flags; | |
774 | ||
775 | if (!ab) | |
776 | return; | |
777 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
778 | list_add_tail(&ab->list, &audit_txlist); | |
779 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
780 | ||
781 | tasklet_schedule(&audit_tasklet); | |
782 | } | |
783 | ||
784 | /* Send the message in the audit buffer directly to user space. May not | |
785 | * be called in an irq context. */ | |
786 | static void audit_log_end_fast(struct audit_buffer *ab) | |
787 | { | |
788 | unsigned long flags; | |
789 | ||
790 | BUG_ON(in_irq()); | |
791 | if (!ab) | |
792 | return; | |
793 | if (!audit_rate_check()) { | |
794 | audit_log_lost("rate limit exceeded"); | |
795 | } else { | |
796 | audit_log_move(ab); | |
797 | if (audit_log_drain(ab)) | |
798 | return; | |
799 | } | |
800 | ||
801 | atomic_dec(&audit_backlog); | |
802 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
803 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
804 | kfree(ab); | |
805 | else | |
806 | list_add(&ab->list, &audit_freelist); | |
807 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
808 | } | |
809 | ||
810 | /* Send or queue the message in the audit buffer, depending on the | |
811 | * current context. (A convenience function that may be called in any | |
812 | * context.) */ | |
813 | void audit_log_end(struct audit_buffer *ab) | |
814 | { | |
815 | if (in_irq()) | |
816 | audit_log_end_irq(ab); | |
817 | else | |
818 | audit_log_end_fast(ab); | |
819 | } | |
820 | ||
821 | /* Log an audit record. This is a convenience function that calls | |
822 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
823 | * called in any context. */ | |
824 | void audit_log(struct audit_context *ctx, const char *fmt, ...) | |
825 | { | |
826 | struct audit_buffer *ab; | |
827 | va_list args; | |
828 | ||
829 | ab = audit_log_start(ctx); | |
830 | if (ab) { | |
831 | va_start(args, fmt); | |
832 | audit_log_vformat(ab, fmt, args); | |
833 | va_end(args); | |
834 | audit_log_end(ab); | |
835 | } | |
836 | } |