Commit | Line | Data |
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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. */ | |
c2f0c7c3 | 71 | int audit_pid; |
1da177e4 LT |
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 | ||
c2f0c7c3 SG |
82 | /* The identity of the user shutting down the audit system. */ |
83 | uid_t audit_sig_uid = -1; | |
84 | pid_t audit_sig_pid = -1; | |
85 | ||
1da177e4 LT |
86 | /* Records can be lost in several ways: |
87 | 0) [suppressed in audit_alloc] | |
88 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] | |
89 | 2) out of memory in audit_log_move [alloc_skb] | |
90 | 3) suppressed due to audit_rate_limit | |
91 | 4) suppressed due to audit_backlog_limit | |
92 | */ | |
93 | static atomic_t audit_lost = ATOMIC_INIT(0); | |
94 | ||
95 | /* The netlink socket. */ | |
96 | static struct sock *audit_sock; | |
97 | ||
98 | /* There are two lists of audit buffers. The txlist contains audit | |
99 | * buffers that cannot be sent immediately to the netlink device because | |
100 | * we are in an irq context (these are sent later in a tasklet). | |
101 | * | |
102 | * The second list is a list of pre-allocated audit buffers (if more | |
103 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of | |
104 | * being placed on the freelist). */ | |
105 | static DEFINE_SPINLOCK(audit_txlist_lock); | |
106 | static DEFINE_SPINLOCK(audit_freelist_lock); | |
107 | static int audit_freelist_count = 0; | |
108 | static LIST_HEAD(audit_txlist); | |
109 | static LIST_HEAD(audit_freelist); | |
110 | ||
111 | /* There are three lists of rules -- one to search at task creation | |
112 | * time, one to search at syscall entry time, and another to search at | |
113 | * syscall exit time. */ | |
114 | static LIST_HEAD(audit_tsklist); | |
115 | static LIST_HEAD(audit_entlist); | |
116 | static LIST_HEAD(audit_extlist); | |
117 | ||
118 | /* The netlink socket is only to be read by 1 CPU, which lets us assume | |
119 | * that list additions and deletions never happen simultaneiously in | |
120 | * auditsc.c */ | |
121 | static DECLARE_MUTEX(audit_netlink_sem); | |
122 | ||
123 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
124 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
125 | * should be at least that large. */ | |
126 | #define AUDIT_BUFSIZ 1024 | |
127 | ||
128 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
129 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
130 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
131 | ||
132 | /* The audit_buffer is used when formatting an audit record. The caller | |
133 | * locks briefly to get the record off the freelist or to allocate the | |
134 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
135 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
136 | * use simultaneously. */ | |
137 | struct audit_buffer { | |
138 | struct list_head list; | |
8fc6115c | 139 | struct sk_buff *skb; /* formatted skb ready to send */ |
1da177e4 | 140 | struct audit_context *ctx; /* NULL or associated context */ |
1da177e4 LT |
141 | }; |
142 | ||
143 | void audit_set_type(struct audit_buffer *ab, int type) | |
144 | { | |
5ac52f33 CW |
145 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; |
146 | nlh->nlmsg_type = type; | |
147 | } | |
148 | ||
149 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) | |
150 | { | |
151 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
152 | nlh->nlmsg_pid = pid; | |
1da177e4 LT |
153 | } |
154 | ||
155 | struct audit_entry { | |
156 | struct list_head list; | |
157 | struct audit_rule rule; | |
158 | }; | |
159 | ||
160 | static void audit_log_end_irq(struct audit_buffer *ab); | |
161 | static void audit_log_end_fast(struct audit_buffer *ab); | |
162 | ||
163 | static void audit_panic(const char *message) | |
164 | { | |
165 | switch (audit_failure) | |
166 | { | |
167 | case AUDIT_FAIL_SILENT: | |
168 | break; | |
169 | case AUDIT_FAIL_PRINTK: | |
170 | printk(KERN_ERR "audit: %s\n", message); | |
171 | break; | |
172 | case AUDIT_FAIL_PANIC: | |
173 | panic("audit: %s\n", message); | |
174 | break; | |
175 | } | |
176 | } | |
177 | ||
178 | static inline int audit_rate_check(void) | |
179 | { | |
180 | static unsigned long last_check = 0; | |
181 | static int messages = 0; | |
182 | static DEFINE_SPINLOCK(lock); | |
183 | unsigned long flags; | |
184 | unsigned long now; | |
185 | unsigned long elapsed; | |
186 | int retval = 0; | |
187 | ||
188 | if (!audit_rate_limit) return 1; | |
189 | ||
190 | spin_lock_irqsave(&lock, flags); | |
191 | if (++messages < audit_rate_limit) { | |
192 | retval = 1; | |
193 | } else { | |
194 | now = jiffies; | |
195 | elapsed = now - last_check; | |
196 | if (elapsed > HZ) { | |
197 | last_check = now; | |
198 | messages = 0; | |
199 | retval = 1; | |
200 | } | |
201 | } | |
202 | spin_unlock_irqrestore(&lock, flags); | |
203 | ||
204 | return retval; | |
205 | } | |
206 | ||
207 | /* Emit at least 1 message per second, even if audit_rate_check is | |
208 | * throttling. */ | |
209 | void audit_log_lost(const char *message) | |
210 | { | |
211 | static unsigned long last_msg = 0; | |
212 | static DEFINE_SPINLOCK(lock); | |
213 | unsigned long flags; | |
214 | unsigned long now; | |
215 | int print; | |
216 | ||
217 | atomic_inc(&audit_lost); | |
218 | ||
219 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
220 | ||
221 | if (!print) { | |
222 | spin_lock_irqsave(&lock, flags); | |
223 | now = jiffies; | |
224 | if (now - last_msg > HZ) { | |
225 | print = 1; | |
226 | last_msg = now; | |
227 | } | |
228 | spin_unlock_irqrestore(&lock, flags); | |
229 | } | |
230 | ||
231 | if (print) { | |
232 | printk(KERN_WARNING | |
233 | "audit: audit_lost=%d audit_backlog=%d" | |
234 | " audit_rate_limit=%d audit_backlog_limit=%d\n", | |
235 | atomic_read(&audit_lost), | |
236 | atomic_read(&audit_backlog), | |
237 | audit_rate_limit, | |
238 | audit_backlog_limit); | |
239 | audit_panic(message); | |
240 | } | |
241 | ||
242 | } | |
243 | ||
c94c257c | 244 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
245 | { |
246 | int old = audit_rate_limit; | |
247 | audit_rate_limit = limit; | |
c94c257c SH |
248 | audit_log(NULL, "audit_rate_limit=%d old=%d by auid %u", |
249 | audit_rate_limit, old, loginuid); | |
1da177e4 LT |
250 | return old; |
251 | } | |
252 | ||
c94c257c | 253 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
254 | { |
255 | int old = audit_backlog_limit; | |
256 | audit_backlog_limit = limit; | |
c94c257c SH |
257 | audit_log(NULL, "audit_backlog_limit=%d old=%d by auid %u", |
258 | audit_backlog_limit, old, loginuid); | |
1da177e4 LT |
259 | return old; |
260 | } | |
261 | ||
c94c257c | 262 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
263 | { |
264 | int old = audit_enabled; | |
265 | if (state != 0 && state != 1) | |
266 | return -EINVAL; | |
267 | audit_enabled = state; | |
c94c257c SH |
268 | audit_log(NULL, "audit_enabled=%d old=%d by auid %u", |
269 | audit_enabled, old, loginuid); | |
1da177e4 LT |
270 | return old; |
271 | } | |
272 | ||
c94c257c | 273 | static int audit_set_failure(int state, uid_t loginuid) |
1da177e4 LT |
274 | { |
275 | int old = audit_failure; | |
276 | if (state != AUDIT_FAIL_SILENT | |
277 | && state != AUDIT_FAIL_PRINTK | |
278 | && state != AUDIT_FAIL_PANIC) | |
279 | return -EINVAL; | |
280 | audit_failure = state; | |
c94c257c SH |
281 | audit_log(NULL, "audit_failure=%d old=%d by auid %u", |
282 | audit_failure, old, loginuid); | |
1da177e4 LT |
283 | return old; |
284 | } | |
285 | ||
1da177e4 LT |
286 | void audit_send_reply(int pid, int seq, int type, int done, int multi, |
287 | void *payload, int size) | |
288 | { | |
289 | struct sk_buff *skb; | |
290 | struct nlmsghdr *nlh; | |
291 | int len = NLMSG_SPACE(size); | |
292 | void *data; | |
293 | int flags = multi ? NLM_F_MULTI : 0; | |
294 | int t = done ? NLMSG_DONE : type; | |
295 | ||
296 | skb = alloc_skb(len, GFP_KERNEL); | |
297 | if (!skb) | |
298 | goto nlmsg_failure; | |
299 | ||
300 | nlh = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh)); | |
301 | nlh->nlmsg_flags = flags; | |
302 | data = NLMSG_DATA(nlh); | |
303 | memcpy(data, payload, size); | |
304 | netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT); | |
305 | return; | |
306 | ||
307 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
308 | if (skb) | |
309 | kfree_skb(skb); | |
310 | } | |
311 | ||
312 | /* | |
313 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
314 | * control messages. | |
315 | */ | |
316 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
317 | { | |
318 | int err = 0; | |
319 | ||
320 | switch (msg_type) { | |
321 | case AUDIT_GET: | |
322 | case AUDIT_LIST: | |
323 | case AUDIT_SET: | |
324 | case AUDIT_ADD: | |
325 | case AUDIT_DEL: | |
c2f0c7c3 | 326 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
327 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
328 | err = -EPERM; | |
329 | break; | |
330 | case AUDIT_USER: | |
331 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) | |
332 | err = -EPERM; | |
333 | break; | |
334 | default: /* bad msg */ | |
335 | err = -EINVAL; | |
336 | } | |
337 | ||
338 | return err; | |
339 | } | |
340 | ||
341 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
342 | { | |
343 | u32 uid, pid, seq; | |
344 | void *data; | |
345 | struct audit_status *status_get, status_set; | |
346 | int err; | |
347 | struct audit_buffer *ab; | |
348 | u16 msg_type = nlh->nlmsg_type; | |
c94c257c | 349 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 350 | struct audit_sig_info sig_data; |
1da177e4 LT |
351 | |
352 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
353 | if (err) | |
354 | return err; | |
355 | ||
356 | pid = NETLINK_CREDS(skb)->pid; | |
357 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 358 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
359 | seq = nlh->nlmsg_seq; |
360 | data = NLMSG_DATA(nlh); | |
361 | ||
362 | switch (msg_type) { | |
363 | case AUDIT_GET: | |
364 | status_set.enabled = audit_enabled; | |
365 | status_set.failure = audit_failure; | |
366 | status_set.pid = audit_pid; | |
367 | status_set.rate_limit = audit_rate_limit; | |
368 | status_set.backlog_limit = audit_backlog_limit; | |
369 | status_set.lost = atomic_read(&audit_lost); | |
370 | status_set.backlog = atomic_read(&audit_backlog); | |
371 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
372 | &status_set, sizeof(status_set)); | |
373 | break; | |
374 | case AUDIT_SET: | |
375 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
376 | return -EINVAL; | |
377 | status_get = (struct audit_status *)data; | |
378 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 379 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
380 | if (err < 0) return err; |
381 | } | |
382 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 383 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
384 | if (err < 0) return err; |
385 | } | |
386 | if (status_get->mask & AUDIT_STATUS_PID) { | |
387 | int old = audit_pid; | |
388 | audit_pid = status_get->pid; | |
c94c257c SH |
389 | audit_log(NULL, "audit_pid=%d old=%d by auid %u", |
390 | audit_pid, old, loginuid); | |
1da177e4 LT |
391 | } |
392 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 393 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 394 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
395 | audit_set_backlog_limit(status_get->backlog_limit, |
396 | loginuid); | |
1da177e4 LT |
397 | break; |
398 | case AUDIT_USER: | |
399 | ab = audit_log_start(NULL); | |
400 | if (!ab) | |
401 | break; /* audit_panic has been called */ | |
402 | audit_log_format(ab, | |
c94c257c SH |
403 | "user pid=%d uid=%d length=%d loginuid=%u" |
404 | " msg='%.1024s'", | |
1da177e4 LT |
405 | pid, uid, |
406 | (int)(nlh->nlmsg_len | |
407 | - ((char *)data - (char *)nlh)), | |
c94c257c | 408 | loginuid, (char *)data); |
5ac52f33 CW |
409 | audit_set_type(ab, AUDIT_USER); |
410 | audit_set_pid(ab, pid); | |
1da177e4 LT |
411 | audit_log_end(ab); |
412 | break; | |
413 | case AUDIT_ADD: | |
414 | case AUDIT_DEL: | |
415 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
416 | return -EINVAL; | |
417 | /* fallthrough */ | |
418 | case AUDIT_LIST: | |
419 | #ifdef CONFIG_AUDITSYSCALL | |
420 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, | |
c94c257c | 421 | uid, seq, data, loginuid); |
1da177e4 LT |
422 | #else |
423 | err = -EOPNOTSUPP; | |
424 | #endif | |
425 | break; | |
c2f0c7c3 SG |
426 | case AUDIT_SIGNAL_INFO: |
427 | sig_data.uid = audit_sig_uid; | |
428 | sig_data.pid = audit_sig_pid; | |
429 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
430 | 0, 0, &sig_data, sizeof(sig_data)); | |
431 | break; | |
1da177e4 LT |
432 | default: |
433 | err = -EINVAL; | |
434 | break; | |
435 | } | |
436 | ||
437 | return err < 0 ? err : 0; | |
438 | } | |
439 | ||
440 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
441 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
442 | * discarded silently. */ | |
2a0a6ebe | 443 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
444 | { |
445 | int err; | |
446 | struct nlmsghdr *nlh; | |
447 | u32 rlen; | |
448 | ||
449 | while (skb->len >= NLMSG_SPACE(0)) { | |
450 | nlh = (struct nlmsghdr *)skb->data; | |
451 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 452 | return; |
1da177e4 LT |
453 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
454 | if (rlen > skb->len) | |
455 | rlen = skb->len; | |
456 | if ((err = audit_receive_msg(skb, nlh))) { | |
457 | netlink_ack(skb, nlh, err); | |
458 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
459 | netlink_ack(skb, nlh, 0); | |
460 | skb_pull(skb, rlen); | |
461 | } | |
1da177e4 LT |
462 | } |
463 | ||
464 | /* Receive messages from netlink socket. */ | |
465 | static void audit_receive(struct sock *sk, int length) | |
466 | { | |
467 | struct sk_buff *skb; | |
2a0a6ebe | 468 | unsigned int qlen; |
1da177e4 | 469 | |
2a0a6ebe | 470 | down(&audit_netlink_sem); |
1da177e4 | 471 | |
2a0a6ebe HX |
472 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
473 | skb = skb_dequeue(&sk->sk_receive_queue); | |
474 | audit_receive_skb(skb); | |
475 | kfree_skb(skb); | |
1da177e4 LT |
476 | } |
477 | up(&audit_netlink_sem); | |
478 | } | |
479 | ||
5ac52f33 | 480 | /* Grab skbuff from the audit_buffer and send to user space. */ |
1da177e4 LT |
481 | static inline int audit_log_drain(struct audit_buffer *ab) |
482 | { | |
8fc6115c | 483 | struct sk_buff *skb = ab->skb; |
1da177e4 | 484 | |
8fc6115c | 485 | if (skb) { |
1da177e4 LT |
486 | int retval = 0; |
487 | ||
488 | if (audit_pid) { | |
5ac52f33 | 489 | struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data; |
5a241d77 | 490 | nlh->nlmsg_len = skb->len - NLMSG_SPACE(0); |
1da177e4 LT |
491 | skb_get(skb); /* because netlink_* frees */ |
492 | retval = netlink_unicast(audit_sock, skb, audit_pid, | |
493 | MSG_DONTWAIT); | |
494 | } | |
37509e74 CW |
495 | if (retval == -EAGAIN && |
496 | (atomic_read(&audit_backlog)) < audit_backlog_limit) { | |
1da177e4 LT |
497 | audit_log_end_irq(ab); |
498 | return 1; | |
499 | } | |
500 | if (retval < 0) { | |
501 | if (retval == -ECONNREFUSED) { | |
502 | printk(KERN_ERR | |
503 | "audit: *NO* daemon at audit_pid=%d\n", | |
504 | audit_pid); | |
505 | audit_pid = 0; | |
506 | } else | |
507 | audit_log_lost("netlink socket too busy"); | |
508 | } | |
509 | if (!audit_pid) { /* No daemon */ | |
8fc6115c | 510 | int offset = NLMSG_SPACE(0); |
1da177e4 | 511 | int len = skb->len - offset; |
c7fcb0ee PM |
512 | skb->data[offset + len] = '\0'; |
513 | printk(KERN_ERR "%s\n", skb->data + offset); | |
1da177e4 | 514 | } |
1da177e4 LT |
515 | } |
516 | return 0; | |
517 | } | |
518 | ||
519 | /* Initialize audit support at boot time. */ | |
520 | static int __init audit_init(void) | |
521 | { | |
522 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
523 | audit_default ? "enabled" : "disabled"); | |
524 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
525 | if (!audit_sock) | |
526 | audit_panic("cannot initialize netlink socket"); | |
527 | ||
528 | audit_initialized = 1; | |
529 | audit_enabled = audit_default; | |
530 | audit_log(NULL, "initialized"); | |
531 | return 0; | |
532 | } | |
1da177e4 LT |
533 | __initcall(audit_init); |
534 | ||
535 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
536 | static int __init audit_enable(char *str) | |
537 | { | |
538 | audit_default = !!simple_strtol(str, NULL, 0); | |
539 | printk(KERN_INFO "audit: %s%s\n", | |
540 | audit_default ? "enabled" : "disabled", | |
541 | audit_initialized ? "" : " (after initialization)"); | |
542 | if (audit_initialized) | |
543 | audit_enabled = audit_default; | |
544 | return 0; | |
545 | } | |
546 | ||
547 | __setup("audit=", audit_enable); | |
548 | ||
16e1904e CW |
549 | static void audit_buffer_free(struct audit_buffer *ab) |
550 | { | |
551 | unsigned long flags; | |
552 | ||
8fc6115c CW |
553 | if (!ab) |
554 | return; | |
555 | ||
5ac52f33 CW |
556 | if (ab->skb) |
557 | kfree_skb(ab->skb); | |
16e1904e CW |
558 | atomic_dec(&audit_backlog); |
559 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
560 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
561 | kfree(ab); | |
562 | else | |
563 | list_add(&ab->list, &audit_freelist); | |
564 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
565 | } | |
566 | ||
8fc6115c CW |
567 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
568 | int gfp_mask) | |
16e1904e CW |
569 | { |
570 | unsigned long flags; | |
571 | struct audit_buffer *ab = NULL; | |
5ac52f33 | 572 | struct nlmsghdr *nlh; |
16e1904e CW |
573 | |
574 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
575 | if (!list_empty(&audit_freelist)) { | |
576 | ab = list_entry(audit_freelist.next, | |
577 | struct audit_buffer, list); | |
578 | list_del(&ab->list); | |
579 | --audit_freelist_count; | |
580 | } | |
581 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
582 | ||
583 | if (!ab) { | |
4332bdd3 | 584 | ab = kmalloc(sizeof(*ab), gfp_mask); |
16e1904e | 585 | if (!ab) |
8fc6115c | 586 | goto err; |
16e1904e CW |
587 | } |
588 | atomic_inc(&audit_backlog); | |
8fc6115c | 589 | |
4332bdd3 | 590 | ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); |
5ac52f33 | 591 | if (!ab->skb) |
8fc6115c CW |
592 | goto err; |
593 | ||
8fc6115c | 594 | ab->ctx = ctx; |
5ac52f33 CW |
595 | nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); |
596 | nlh->nlmsg_type = AUDIT_KERNEL; | |
597 | nlh->nlmsg_flags = 0; | |
598 | nlh->nlmsg_pid = 0; | |
599 | nlh->nlmsg_seq = 0; | |
16e1904e | 600 | return ab; |
8fc6115c CW |
601 | err: |
602 | audit_buffer_free(ab); | |
603 | return NULL; | |
16e1904e | 604 | } |
1da177e4 LT |
605 | |
606 | /* Obtain an audit buffer. This routine does locking to obtain the | |
607 | * audit buffer, but then no locking is required for calls to | |
608 | * audit_log_*format. If the tsk is a task that is currently in a | |
609 | * syscall, then the syscall is marked as auditable and an audit record | |
610 | * will be written at syscall exit. If there is no associated task, tsk | |
611 | * should be NULL. */ | |
612 | struct audit_buffer *audit_log_start(struct audit_context *ctx) | |
613 | { | |
614 | struct audit_buffer *ab = NULL; | |
1da177e4 | 615 | struct timespec t; |
d812ddbb | 616 | unsigned int serial; |
1da177e4 LT |
617 | |
618 | if (!audit_initialized) | |
619 | return NULL; | |
620 | ||
621 | if (audit_backlog_limit | |
622 | && atomic_read(&audit_backlog) > audit_backlog_limit) { | |
623 | if (audit_rate_check()) | |
624 | printk(KERN_WARNING | |
625 | "audit: audit_backlog=%d > " | |
626 | "audit_backlog_limit=%d\n", | |
627 | atomic_read(&audit_backlog), | |
628 | audit_backlog_limit); | |
629 | audit_log_lost("backlog limit exceeded"); | |
630 | return NULL; | |
631 | } | |
632 | ||
8fc6115c | 633 | ab = audit_buffer_alloc(ctx, GFP_ATOMIC); |
1da177e4 LT |
634 | if (!ab) { |
635 | audit_log_lost("out of memory in audit_log_start"); | |
636 | return NULL; | |
637 | } | |
638 | ||
1da177e4 LT |
639 | #ifdef CONFIG_AUDITSYSCALL |
640 | if (ab->ctx) | |
641 | audit_get_stamp(ab->ctx, &t, &serial); | |
642 | else | |
643 | #endif | |
d812ddbb | 644 | { |
1da177e4 | 645 | t = CURRENT_TIME; |
d812ddbb SG |
646 | serial = 0; |
647 | } | |
1da177e4 LT |
648 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
649 | t.tv_sec, t.tv_nsec/1000000, serial); | |
650 | return ab; | |
651 | } | |
652 | ||
8fc6115c | 653 | /** |
5ac52f33 | 654 | * audit_expand - expand skb in the audit buffer |
8fc6115c CW |
655 | * @ab: audit_buffer |
656 | * | |
657 | * Returns 0 (no space) on failed expansion, or available space if | |
658 | * successful. | |
659 | */ | |
e3b926b4 | 660 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
8fc6115c | 661 | { |
5ac52f33 | 662 | struct sk_buff *skb = ab->skb; |
e3b926b4 | 663 | int ret = pskb_expand_head(skb, skb_headroom(skb), extra, |
5ac52f33 CW |
664 | GFP_ATOMIC); |
665 | if (ret < 0) { | |
666 | audit_log_lost("out of memory in audit_expand"); | |
8fc6115c | 667 | return 0; |
5ac52f33 CW |
668 | } |
669 | return skb_tailroom(skb); | |
8fc6115c | 670 | } |
1da177e4 LT |
671 | |
672 | /* Format an audit message into the audit buffer. If there isn't enough | |
673 | * room in the audit buffer, more room will be allocated and vsnprint | |
674 | * will be called a second time. Currently, we assume that a printk | |
675 | * can't format message larger than 1024 bytes, so we don't either. */ | |
676 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
677 | va_list args) | |
678 | { | |
679 | int len, avail; | |
5ac52f33 | 680 | struct sk_buff *skb; |
eecb0a73 | 681 | va_list args2; |
1da177e4 LT |
682 | |
683 | if (!ab) | |
684 | return; | |
685 | ||
5ac52f33 CW |
686 | BUG_ON(!ab->skb); |
687 | skb = ab->skb; | |
688 | avail = skb_tailroom(skb); | |
689 | if (avail == 0) { | |
e3b926b4 | 690 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
8fc6115c CW |
691 | if (!avail) |
692 | goto out; | |
1da177e4 | 693 | } |
eecb0a73 | 694 | va_copy(args2, args); |
5ac52f33 | 695 | len = vsnprintf(skb->tail, avail, fmt, args); |
1da177e4 LT |
696 | if (len >= avail) { |
697 | /* The printk buffer is 1024 bytes long, so if we get | |
698 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
699 | * log everything that printk could have logged. */ | |
e3b926b4 | 700 | avail = audit_expand(ab, 1+len-avail); |
8fc6115c CW |
701 | if (!avail) |
702 | goto out; | |
eecb0a73 | 703 | len = vsnprintf(skb->tail, avail, fmt, args2); |
1da177e4 | 704 | } |
5ac52f33 | 705 | skb_put(skb, (len < avail) ? len : avail); |
8fc6115c CW |
706 | out: |
707 | return; | |
1da177e4 LT |
708 | } |
709 | ||
710 | /* Format a message into the audit buffer. All the work is done in | |
711 | * audit_log_vformat. */ | |
712 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
713 | { | |
714 | va_list args; | |
715 | ||
716 | if (!ab) | |
717 | return; | |
718 | va_start(args, fmt); | |
719 | audit_log_vformat(ab, fmt, args); | |
720 | va_end(args); | |
721 | } | |
722 | ||
83c7d091 | 723 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len) |
724 | { | |
725 | int i; | |
726 | ||
727 | for (i=0; i<len; i++) | |
728 | audit_log_format(ab, "%02x", buf[i]); | |
729 | } | |
730 | ||
731 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) | |
732 | { | |
81b7854d | 733 | const unsigned char *p = string; |
83c7d091 | 734 | |
735 | while (*p) { | |
736 | if (*p == '"' || *p == ' ' || *p < 0x20 || *p > 0x7f) { | |
737 | audit_log_hex(ab, string, strlen(string)); | |
738 | return; | |
739 | } | |
740 | p++; | |
741 | } | |
742 | audit_log_format(ab, "\"%s\"", string); | |
743 | } | |
744 | ||
745 | ||
1da177e4 LT |
746 | /* This is a helper-function to print the d_path without using a static |
747 | * buffer or allocating another buffer in addition to the one in | |
748 | * audit_buffer. */ | |
749 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
750 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
751 | { | |
752 | char *p; | |
5ac52f33 | 753 | struct sk_buff *skb = ab->skb; |
1da177e4 LT |
754 | int len, avail; |
755 | ||
8fc6115c CW |
756 | if (prefix) |
757 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 758 | |
5ac52f33 CW |
759 | avail = skb_tailroom(skb); |
760 | p = d_path(dentry, vfsmnt, skb->tail, avail); | |
1da177e4 LT |
761 | if (IS_ERR(p)) { |
762 | /* FIXME: can we save some information here? */ | |
763 | audit_log_format(ab, "<toolong>"); | |
764 | } else { | |
5ac52f33 CW |
765 | /* path isn't at start of buffer */ |
766 | len = ((char *)skb->tail + avail - 1) - p; | |
767 | memmove(skb->tail, p, len); | |
768 | skb_put(skb, len); | |
1da177e4 LT |
769 | } |
770 | } | |
771 | ||
772 | /* Remove queued messages from the audit_txlist and send them to userspace. */ | |
773 | static void audit_tasklet_handler(unsigned long arg) | |
774 | { | |
775 | LIST_HEAD(list); | |
776 | struct audit_buffer *ab; | |
777 | unsigned long flags; | |
778 | ||
779 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
780 | list_splice_init(&audit_txlist, &list); | |
781 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
782 | ||
783 | while (!list_empty(&list)) { | |
784 | ab = list_entry(list.next, struct audit_buffer, list); | |
785 | list_del(&ab->list); | |
786 | audit_log_end_fast(ab); | |
787 | } | |
788 | } | |
789 | ||
790 | static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0); | |
791 | ||
792 | /* The netlink_* functions cannot be called inside an irq context, so | |
793 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
794 | * remove them from the queue outside the irq context. May be called in | |
795 | * any context. */ | |
796 | static void audit_log_end_irq(struct audit_buffer *ab) | |
797 | { | |
798 | unsigned long flags; | |
799 | ||
800 | if (!ab) | |
801 | return; | |
802 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
803 | list_add_tail(&ab->list, &audit_txlist); | |
804 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
805 | ||
806 | tasklet_schedule(&audit_tasklet); | |
807 | } | |
808 | ||
809 | /* Send the message in the audit buffer directly to user space. May not | |
810 | * be called in an irq context. */ | |
811 | static void audit_log_end_fast(struct audit_buffer *ab) | |
812 | { | |
1da177e4 LT |
813 | BUG_ON(in_irq()); |
814 | if (!ab) | |
815 | return; | |
816 | if (!audit_rate_check()) { | |
817 | audit_log_lost("rate limit exceeded"); | |
818 | } else { | |
1da177e4 LT |
819 | if (audit_log_drain(ab)) |
820 | return; | |
821 | } | |
16e1904e | 822 | audit_buffer_free(ab); |
1da177e4 LT |
823 | } |
824 | ||
825 | /* Send or queue the message in the audit buffer, depending on the | |
826 | * current context. (A convenience function that may be called in any | |
827 | * context.) */ | |
828 | void audit_log_end(struct audit_buffer *ab) | |
829 | { | |
830 | if (in_irq()) | |
831 | audit_log_end_irq(ab); | |
832 | else | |
833 | audit_log_end_fast(ab); | |
834 | } | |
835 | ||
836 | /* Log an audit record. This is a convenience function that calls | |
837 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
838 | * called in any context. */ | |
839 | void audit_log(struct audit_context *ctx, const char *fmt, ...) | |
840 | { | |
841 | struct audit_buffer *ab; | |
842 | va_list args; | |
843 | ||
844 | ab = audit_log_start(ctx); | |
845 | if (ab) { | |
846 | va_start(args, fmt); | |
847 | audit_log_vformat(ab, fmt, args); | |
848 | va_end(args); | |
849 | audit_log_end(ab); | |
850 | } | |
851 | } |