Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/kernel/audit.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 23723 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* audit.c -- Auditing support |
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/sgrubb/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 | }; |
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 | |
241 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
242 | { |
243 | int old = audit_rate_limit; |
244 | audit_rate_limit = limit; |
245 | audit_log(NULL, "audit_rate_limit=%d old=%d by auid %u", |
246 | audit_rate_limit, old, loginuid); |
247 | return old; |
248 | } |
249 | |
250 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
251 | { |
252 | int old = audit_backlog_limit; |
253 | audit_backlog_limit = limit; |
254 | audit_log(NULL, "audit_backlog_limit=%d old=%d by auid %u", |
255 | audit_backlog_limit, old, loginuid); |
256 | return old; |
257 | } |
258 | |
259 | static int audit_set_enabled(int state, uid_t loginuid) |
260 | { |
261 | int old = audit_enabled; |
262 | if (state != 0 && state != 1) |
263 | return -EINVAL; |
264 | audit_enabled = state; |
265 | audit_log(NULL, "audit_enabled=%d old=%d by auid %u", |
266 | audit_enabled, old, loginuid); |
267 | return old; |
268 | } |
269 | |
270 | static int audit_set_failure(int state, uid_t loginuid) |
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; |
278 | audit_log(NULL, "audit_failure=%d old=%d by auid %u", |
279 | audit_failure, old, loginuid); |
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; |
346 | uid_t loginuid; /* loginuid of sender */ |
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 | loginuid = NETLINK_CB(skb).loginuid; |
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) { |
375 | err = audit_set_enabled(status_get->enabled, loginuid); |
376 | if (err < 0) return err; |
377 | } |
378 | if (status_get->mask & AUDIT_STATUS_FAILURE) { |
379 | err = audit_set_failure(status_get->failure, loginuid); |
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; |
385 | audit_log(NULL, "audit_pid=%d old=%d by auid %u", |
386 | audit_pid, old, loginuid); |
387 | } |
388 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) |
389 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
390 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
391 | audit_set_backlog_limit(status_get->backlog_limit, |
392 | loginuid); |
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, |
399 | "user pid=%d uid=%d length=%d loginuid=%u" |
400 | " msg='%.1024s'", |
401 | pid, uid, |
402 | (int)(nlh->nlmsg_len |
403 | - ((char *)data - (char *)nlh)), |
404 | loginuid, (char *)data); |
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, |
417 | uid, seq, data, loginuid); |
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. */ |
433 | static void audit_receive_skb(struct sk_buff *skb) |
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) |
442 | return; |
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 | } |
452 | } |
453 | |
454 | /* Receive messages from netlink socket. */ |
455 | static void audit_receive(struct sock *sk, int length) |
456 | { |
457 | struct sk_buff *skb; |
458 | unsigned int qlen; |
459 | |
460 | down(&audit_netlink_sem); |
461 | |
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); |
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 | |
486 | skb = skb_peek_tail(&ab->sklist); |
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 | } |
525 | if (retval == -EAGAIN && |
526 | (atomic_read(&audit_backlog)) < audit_backlog_limit) { |
527 | skb_queue_head(&ab->sklist, skb); |
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; |
543 | skb->data[offset + len] = '\0'; |
544 | printk(KERN_ERR "%s\n", skb->data + offset); |
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; |
623 | unsigned int serial; |
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; |
665 | |
666 | #ifdef CONFIG_AUDITSYSCALL |
667 | if (ab->ctx) |
668 | audit_get_stamp(ab->ctx, &t, &serial); |
669 | else |
670 | #endif |
671 | { |
672 | t = CURRENT_TIME; |
673 | serial = 0; |
674 | } |
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 | |
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 | { |
734 | const unsigned char *p = string; |
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 | |
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 | } |