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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 | |
23f32d18 | 119 | * that list additions and deletions never happen simultaneously in |
1da177e4 LT |
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 | ||
c0404993 SG |
143 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
144 | { | |
145 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
146 | nlh->nlmsg_pid = pid; | |
147 | } | |
148 | ||
1da177e4 LT |
149 | struct audit_entry { |
150 | struct list_head list; | |
151 | struct audit_rule rule; | |
152 | }; | |
153 | ||
154 | static void audit_log_end_irq(struct audit_buffer *ab); | |
155 | static void audit_log_end_fast(struct audit_buffer *ab); | |
156 | ||
157 | static void audit_panic(const char *message) | |
158 | { | |
159 | switch (audit_failure) | |
160 | { | |
161 | case AUDIT_FAIL_SILENT: | |
162 | break; | |
163 | case AUDIT_FAIL_PRINTK: | |
164 | printk(KERN_ERR "audit: %s\n", message); | |
165 | break; | |
166 | case AUDIT_FAIL_PANIC: | |
167 | panic("audit: %s\n", message); | |
168 | break; | |
169 | } | |
170 | } | |
171 | ||
172 | static inline int audit_rate_check(void) | |
173 | { | |
174 | static unsigned long last_check = 0; | |
175 | static int messages = 0; | |
176 | static DEFINE_SPINLOCK(lock); | |
177 | unsigned long flags; | |
178 | unsigned long now; | |
179 | unsigned long elapsed; | |
180 | int retval = 0; | |
181 | ||
182 | if (!audit_rate_limit) return 1; | |
183 | ||
184 | spin_lock_irqsave(&lock, flags); | |
185 | if (++messages < audit_rate_limit) { | |
186 | retval = 1; | |
187 | } else { | |
188 | now = jiffies; | |
189 | elapsed = now - last_check; | |
190 | if (elapsed > HZ) { | |
191 | last_check = now; | |
192 | messages = 0; | |
193 | retval = 1; | |
194 | } | |
195 | } | |
196 | spin_unlock_irqrestore(&lock, flags); | |
197 | ||
198 | return retval; | |
199 | } | |
200 | ||
201 | /* Emit at least 1 message per second, even if audit_rate_check is | |
202 | * throttling. */ | |
203 | void audit_log_lost(const char *message) | |
204 | { | |
205 | static unsigned long last_msg = 0; | |
206 | static DEFINE_SPINLOCK(lock); | |
207 | unsigned long flags; | |
208 | unsigned long now; | |
209 | int print; | |
210 | ||
211 | atomic_inc(&audit_lost); | |
212 | ||
213 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
214 | ||
215 | if (!print) { | |
216 | spin_lock_irqsave(&lock, flags); | |
217 | now = jiffies; | |
218 | if (now - last_msg > HZ) { | |
219 | print = 1; | |
220 | last_msg = now; | |
221 | } | |
222 | spin_unlock_irqrestore(&lock, flags); | |
223 | } | |
224 | ||
225 | if (print) { | |
226 | printk(KERN_WARNING | |
227 | "audit: audit_lost=%d audit_backlog=%d" | |
228 | " audit_rate_limit=%d audit_backlog_limit=%d\n", | |
229 | atomic_read(&audit_lost), | |
230 | atomic_read(&audit_backlog), | |
231 | audit_rate_limit, | |
232 | audit_backlog_limit); | |
233 | audit_panic(message); | |
234 | } | |
235 | ||
236 | } | |
237 | ||
c94c257c | 238 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
239 | { |
240 | int old = audit_rate_limit; | |
241 | audit_rate_limit = limit; | |
c0404993 SG |
242 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
243 | "audit_rate_limit=%d old=%d by auid %u", | |
c94c257c | 244 | audit_rate_limit, old, loginuid); |
1da177e4 LT |
245 | return old; |
246 | } | |
247 | ||
c94c257c | 248 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
249 | { |
250 | int old = audit_backlog_limit; | |
251 | audit_backlog_limit = limit; | |
c0404993 SG |
252 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
253 | "audit_backlog_limit=%d old=%d by auid %u", | |
c94c257c | 254 | audit_backlog_limit, old, loginuid); |
1da177e4 LT |
255 | return old; |
256 | } | |
257 | ||
c94c257c | 258 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
259 | { |
260 | int old = audit_enabled; | |
261 | if (state != 0 && state != 1) | |
262 | return -EINVAL; | |
263 | audit_enabled = state; | |
c0404993 SG |
264 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
265 | "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; | |
c0404993 SG |
278 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
279 | "audit_failure=%d old=%d by auid %u", | |
280 | audit_failure, old, loginuid); | |
1da177e4 LT |
281 | return old; |
282 | } | |
283 | ||
1da177e4 LT |
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: | |
c2f0c7c3 | 324 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
325 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
326 | err = -EPERM; | |
327 | break; | |
328 | case AUDIT_USER: | |
c0404993 SG |
329 | case AUDIT_USER_AUTH: |
330 | case AUDIT_USER_ACCT: | |
331 | case AUDIT_USER_MGMT: | |
332 | case AUDIT_CRED_ACQ: | |
333 | case AUDIT_CRED_DISP: | |
334 | case AUDIT_USER_START: | |
335 | case AUDIT_USER_END: | |
336 | case AUDIT_USER_AVC: | |
1da177e4 LT |
337 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) |
338 | err = -EPERM; | |
339 | break; | |
340 | default: /* bad msg */ | |
341 | err = -EINVAL; | |
342 | } | |
343 | ||
344 | return err; | |
345 | } | |
346 | ||
347 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
348 | { | |
349 | u32 uid, pid, seq; | |
350 | void *data; | |
351 | struct audit_status *status_get, status_set; | |
352 | int err; | |
c0404993 | 353 | struct audit_buffer *ab; |
1da177e4 | 354 | u16 msg_type = nlh->nlmsg_type; |
c94c257c | 355 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 356 | struct audit_sig_info sig_data; |
1da177e4 LT |
357 | |
358 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
359 | if (err) | |
360 | return err; | |
361 | ||
362 | pid = NETLINK_CREDS(skb)->pid; | |
363 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 364 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
365 | seq = nlh->nlmsg_seq; |
366 | data = NLMSG_DATA(nlh); | |
367 | ||
368 | switch (msg_type) { | |
369 | case AUDIT_GET: | |
370 | status_set.enabled = audit_enabled; | |
371 | status_set.failure = audit_failure; | |
372 | status_set.pid = audit_pid; | |
373 | status_set.rate_limit = audit_rate_limit; | |
374 | status_set.backlog_limit = audit_backlog_limit; | |
375 | status_set.lost = atomic_read(&audit_lost); | |
376 | status_set.backlog = atomic_read(&audit_backlog); | |
377 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
378 | &status_set, sizeof(status_set)); | |
379 | break; | |
380 | case AUDIT_SET: | |
381 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
382 | return -EINVAL; | |
383 | status_get = (struct audit_status *)data; | |
384 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 385 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
386 | if (err < 0) return err; |
387 | } | |
388 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 389 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
390 | if (err < 0) return err; |
391 | } | |
392 | if (status_get->mask & AUDIT_STATUS_PID) { | |
393 | int old = audit_pid; | |
394 | audit_pid = status_get->pid; | |
c0404993 SG |
395 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
396 | "audit_pid=%d old=%d by auid %u", | |
c94c257c | 397 | audit_pid, old, loginuid); |
1da177e4 LT |
398 | } |
399 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 400 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 401 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
402 | audit_set_backlog_limit(status_get->backlog_limit, |
403 | loginuid); | |
1da177e4 LT |
404 | break; |
405 | case AUDIT_USER: | |
c0404993 SG |
406 | case AUDIT_USER_AUTH: |
407 | case AUDIT_USER_ACCT: | |
408 | case AUDIT_USER_MGMT: | |
409 | case AUDIT_CRED_ACQ: | |
410 | case AUDIT_CRED_DISP: | |
411 | case AUDIT_USER_START: | |
412 | case AUDIT_USER_END: | |
413 | case AUDIT_USER_AVC: | |
414 | ab = audit_log_start(NULL, msg_type); | |
415 | if (!ab) | |
416 | break; /* audit_panic has been called */ | |
417 | audit_log_format(ab, | |
c94c257c SH |
418 | "user pid=%d uid=%d length=%d loginuid=%u" |
419 | " msg='%.1024s'", | |
1da177e4 LT |
420 | pid, uid, |
421 | (int)(nlh->nlmsg_len | |
422 | - ((char *)data - (char *)nlh)), | |
c94c257c | 423 | loginuid, (char *)data); |
c0404993 SG |
424 | audit_set_pid(ab, pid); |
425 | audit_log_end(ab); | |
1da177e4 LT |
426 | break; |
427 | case AUDIT_ADD: | |
428 | case AUDIT_DEL: | |
429 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
430 | return -EINVAL; | |
431 | /* fallthrough */ | |
432 | case AUDIT_LIST: | |
1da177e4 | 433 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, |
c94c257c | 434 | uid, seq, data, loginuid); |
1da177e4 | 435 | break; |
c2f0c7c3 SG |
436 | case AUDIT_SIGNAL_INFO: |
437 | sig_data.uid = audit_sig_uid; | |
438 | sig_data.pid = audit_sig_pid; | |
439 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
440 | 0, 0, &sig_data, sizeof(sig_data)); | |
441 | break; | |
1da177e4 LT |
442 | default: |
443 | err = -EINVAL; | |
444 | break; | |
445 | } | |
446 | ||
447 | return err < 0 ? err : 0; | |
448 | } | |
449 | ||
450 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
451 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
452 | * discarded silently. */ | |
2a0a6ebe | 453 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
454 | { |
455 | int err; | |
456 | struct nlmsghdr *nlh; | |
457 | u32 rlen; | |
458 | ||
459 | while (skb->len >= NLMSG_SPACE(0)) { | |
460 | nlh = (struct nlmsghdr *)skb->data; | |
461 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 462 | return; |
1da177e4 LT |
463 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
464 | if (rlen > skb->len) | |
465 | rlen = skb->len; | |
466 | if ((err = audit_receive_msg(skb, nlh))) { | |
467 | netlink_ack(skb, nlh, err); | |
468 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
469 | netlink_ack(skb, nlh, 0); | |
470 | skb_pull(skb, rlen); | |
471 | } | |
1da177e4 LT |
472 | } |
473 | ||
474 | /* Receive messages from netlink socket. */ | |
475 | static void audit_receive(struct sock *sk, int length) | |
476 | { | |
477 | struct sk_buff *skb; | |
2a0a6ebe | 478 | unsigned int qlen; |
1da177e4 | 479 | |
2a0a6ebe | 480 | down(&audit_netlink_sem); |
1da177e4 | 481 | |
2a0a6ebe HX |
482 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
483 | skb = skb_dequeue(&sk->sk_receive_queue); | |
484 | audit_receive_skb(skb); | |
485 | kfree_skb(skb); | |
1da177e4 LT |
486 | } |
487 | up(&audit_netlink_sem); | |
488 | } | |
489 | ||
5ac52f33 | 490 | /* Grab skbuff from the audit_buffer and send to user space. */ |
1da177e4 LT |
491 | static inline int audit_log_drain(struct audit_buffer *ab) |
492 | { | |
8fc6115c | 493 | struct sk_buff *skb = ab->skb; |
1da177e4 | 494 | |
8fc6115c | 495 | if (skb) { |
1da177e4 LT |
496 | int retval = 0; |
497 | ||
498 | if (audit_pid) { | |
5ac52f33 | 499 | struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data; |
5a241d77 | 500 | nlh->nlmsg_len = skb->len - NLMSG_SPACE(0); |
1da177e4 LT |
501 | skb_get(skb); /* because netlink_* frees */ |
502 | retval = netlink_unicast(audit_sock, skb, audit_pid, | |
503 | MSG_DONTWAIT); | |
504 | } | |
37509e74 CW |
505 | if (retval == -EAGAIN && |
506 | (atomic_read(&audit_backlog)) < audit_backlog_limit) { | |
1da177e4 LT |
507 | audit_log_end_irq(ab); |
508 | return 1; | |
509 | } | |
510 | if (retval < 0) { | |
511 | if (retval == -ECONNREFUSED) { | |
512 | printk(KERN_ERR | |
513 | "audit: *NO* daemon at audit_pid=%d\n", | |
514 | audit_pid); | |
515 | audit_pid = 0; | |
516 | } else | |
517 | audit_log_lost("netlink socket too busy"); | |
518 | } | |
519 | if (!audit_pid) { /* No daemon */ | |
8fc6115c | 520 | int offset = NLMSG_SPACE(0); |
1da177e4 | 521 | int len = skb->len - offset; |
c7fcb0ee PM |
522 | skb->data[offset + len] = '\0'; |
523 | printk(KERN_ERR "%s\n", skb->data + offset); | |
1da177e4 | 524 | } |
1da177e4 LT |
525 | } |
526 | return 0; | |
527 | } | |
528 | ||
529 | /* Initialize audit support at boot time. */ | |
530 | static int __init audit_init(void) | |
531 | { | |
532 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
533 | audit_default ? "enabled" : "disabled"); | |
534 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
535 | if (!audit_sock) | |
536 | audit_panic("cannot initialize netlink socket"); | |
537 | ||
538 | audit_initialized = 1; | |
539 | audit_enabled = audit_default; | |
c0404993 | 540 | audit_log(NULL, AUDIT_KERNEL, "initialized"); |
1da177e4 LT |
541 | return 0; |
542 | } | |
1da177e4 LT |
543 | __initcall(audit_init); |
544 | ||
545 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
546 | static int __init audit_enable(char *str) | |
547 | { | |
548 | audit_default = !!simple_strtol(str, NULL, 0); | |
549 | printk(KERN_INFO "audit: %s%s\n", | |
550 | audit_default ? "enabled" : "disabled", | |
551 | audit_initialized ? "" : " (after initialization)"); | |
552 | if (audit_initialized) | |
553 | audit_enabled = audit_default; | |
554 | return 0; | |
555 | } | |
556 | ||
557 | __setup("audit=", audit_enable); | |
558 | ||
16e1904e CW |
559 | static void audit_buffer_free(struct audit_buffer *ab) |
560 | { | |
561 | unsigned long flags; | |
562 | ||
8fc6115c CW |
563 | if (!ab) |
564 | return; | |
565 | ||
5ac52f33 CW |
566 | if (ab->skb) |
567 | kfree_skb(ab->skb); | |
16e1904e CW |
568 | atomic_dec(&audit_backlog); |
569 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
570 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
571 | kfree(ab); | |
572 | else | |
573 | list_add(&ab->list, &audit_freelist); | |
574 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
575 | } | |
576 | ||
c0404993 SG |
577 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
578 | int gfp_mask, int type) | |
16e1904e CW |
579 | { |
580 | unsigned long flags; | |
581 | struct audit_buffer *ab = NULL; | |
c0404993 | 582 | struct nlmsghdr *nlh; |
16e1904e CW |
583 | |
584 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
585 | if (!list_empty(&audit_freelist)) { | |
586 | ab = list_entry(audit_freelist.next, | |
587 | struct audit_buffer, list); | |
588 | list_del(&ab->list); | |
589 | --audit_freelist_count; | |
590 | } | |
591 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
592 | ||
593 | if (!ab) { | |
4332bdd3 | 594 | ab = kmalloc(sizeof(*ab), gfp_mask); |
16e1904e | 595 | if (!ab) |
8fc6115c | 596 | goto err; |
16e1904e CW |
597 | } |
598 | atomic_inc(&audit_backlog); | |
8fc6115c | 599 | |
4332bdd3 | 600 | ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); |
5ac52f33 | 601 | if (!ab->skb) |
8fc6115c CW |
602 | goto err; |
603 | ||
c0404993 SG |
604 | ab->ctx = ctx; |
605 | nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); | |
606 | nlh->nlmsg_type = type; | |
607 | nlh->nlmsg_flags = 0; | |
608 | nlh->nlmsg_pid = 0; | |
609 | nlh->nlmsg_seq = 0; | |
16e1904e | 610 | return ab; |
8fc6115c CW |
611 | err: |
612 | audit_buffer_free(ab); | |
613 | return NULL; | |
16e1904e | 614 | } |
1da177e4 LT |
615 | |
616 | /* Obtain an audit buffer. This routine does locking to obtain the | |
617 | * audit buffer, but then no locking is required for calls to | |
618 | * audit_log_*format. If the tsk is a task that is currently in a | |
619 | * syscall, then the syscall is marked as auditable and an audit record | |
620 | * will be written at syscall exit. If there is no associated task, tsk | |
621 | * should be NULL. */ | |
c0404993 | 622 | struct audit_buffer *audit_log_start(struct audit_context *ctx, int type) |
1da177e4 LT |
623 | { |
624 | struct audit_buffer *ab = NULL; | |
1da177e4 | 625 | struct timespec t; |
d812ddbb | 626 | unsigned int serial; |
1da177e4 LT |
627 | |
628 | if (!audit_initialized) | |
629 | return NULL; | |
630 | ||
631 | if (audit_backlog_limit | |
632 | && atomic_read(&audit_backlog) > audit_backlog_limit) { | |
633 | if (audit_rate_check()) | |
634 | printk(KERN_WARNING | |
635 | "audit: audit_backlog=%d > " | |
636 | "audit_backlog_limit=%d\n", | |
637 | atomic_read(&audit_backlog), | |
638 | audit_backlog_limit); | |
639 | audit_log_lost("backlog limit exceeded"); | |
640 | return NULL; | |
641 | } | |
642 | ||
c0404993 | 643 | ab = audit_buffer_alloc(ctx, GFP_ATOMIC, type); |
1da177e4 LT |
644 | if (!ab) { |
645 | audit_log_lost("out of memory in audit_log_start"); | |
646 | return NULL; | |
647 | } | |
648 | ||
197c69c6 | 649 | if (!audit_get_stamp(ab->ctx, &t, &serial)) { |
1da177e4 | 650 | t = CURRENT_TIME; |
d812ddbb SG |
651 | serial = 0; |
652 | } | |
197c69c6 | 653 | |
1da177e4 LT |
654 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
655 | t.tv_sec, t.tv_nsec/1000000, serial); | |
656 | return ab; | |
657 | } | |
658 | ||
8fc6115c | 659 | /** |
5ac52f33 | 660 | * audit_expand - expand skb in the audit buffer |
8fc6115c CW |
661 | * @ab: audit_buffer |
662 | * | |
663 | * Returns 0 (no space) on failed expansion, or available space if | |
664 | * successful. | |
665 | */ | |
e3b926b4 | 666 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
8fc6115c | 667 | { |
5ac52f33 | 668 | struct sk_buff *skb = ab->skb; |
e3b926b4 | 669 | int ret = pskb_expand_head(skb, skb_headroom(skb), extra, |
5ac52f33 CW |
670 | GFP_ATOMIC); |
671 | if (ret < 0) { | |
672 | audit_log_lost("out of memory in audit_expand"); | |
8fc6115c | 673 | return 0; |
5ac52f33 CW |
674 | } |
675 | return skb_tailroom(skb); | |
8fc6115c | 676 | } |
1da177e4 LT |
677 | |
678 | /* Format an audit message into the audit buffer. If there isn't enough | |
679 | * room in the audit buffer, more room will be allocated and vsnprint | |
680 | * will be called a second time. Currently, we assume that a printk | |
681 | * can't format message larger than 1024 bytes, so we don't either. */ | |
682 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
683 | va_list args) | |
684 | { | |
685 | int len, avail; | |
5ac52f33 | 686 | struct sk_buff *skb; |
eecb0a73 | 687 | va_list args2; |
1da177e4 LT |
688 | |
689 | if (!ab) | |
690 | return; | |
691 | ||
5ac52f33 CW |
692 | BUG_ON(!ab->skb); |
693 | skb = ab->skb; | |
694 | avail = skb_tailroom(skb); | |
695 | if (avail == 0) { | |
e3b926b4 | 696 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
8fc6115c CW |
697 | if (!avail) |
698 | goto out; | |
1da177e4 | 699 | } |
eecb0a73 | 700 | va_copy(args2, args); |
5ac52f33 | 701 | len = vsnprintf(skb->tail, avail, fmt, args); |
1da177e4 LT |
702 | if (len >= avail) { |
703 | /* The printk buffer is 1024 bytes long, so if we get | |
704 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
705 | * log everything that printk could have logged. */ | |
9ea74f06 | 706 | avail = audit_expand(ab, max_t(AUDIT_BUFSIZ, 1+len-avail)); |
8fc6115c CW |
707 | if (!avail) |
708 | goto out; | |
eecb0a73 | 709 | len = vsnprintf(skb->tail, avail, fmt, args2); |
1da177e4 | 710 | } |
5ac52f33 | 711 | skb_put(skb, (len < avail) ? len : avail); |
8fc6115c CW |
712 | out: |
713 | return; | |
1da177e4 LT |
714 | } |
715 | ||
716 | /* Format a message into the audit buffer. All the work is done in | |
717 | * audit_log_vformat. */ | |
718 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
719 | { | |
720 | va_list args; | |
721 | ||
722 | if (!ab) | |
723 | return; | |
724 | va_start(args, fmt); | |
725 | audit_log_vformat(ab, fmt, args); | |
726 | va_end(args); | |
727 | } | |
728 | ||
83c7d091 DW |
729 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len) |
730 | { | |
731 | int i; | |
732 | ||
733 | for (i=0; i<len; i++) | |
734 | audit_log_format(ab, "%02x", buf[i]); | |
735 | } | |
736 | ||
737 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) | |
738 | { | |
81b7854d | 739 | const unsigned char *p = string; |
83c7d091 DW |
740 | |
741 | while (*p) { | |
742 | if (*p == '"' || *p == ' ' || *p < 0x20 || *p > 0x7f) { | |
743 | audit_log_hex(ab, string, strlen(string)); | |
744 | return; | |
745 | } | |
746 | p++; | |
747 | } | |
748 | audit_log_format(ab, "\"%s\"", string); | |
749 | } | |
750 | ||
751 | ||
1da177e4 LT |
752 | /* This is a helper-function to print the d_path without using a static |
753 | * buffer or allocating another buffer in addition to the one in | |
754 | * audit_buffer. */ | |
755 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
756 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
757 | { | |
758 | char *p; | |
5ac52f33 | 759 | struct sk_buff *skb = ab->skb; |
1da177e4 LT |
760 | int len, avail; |
761 | ||
8fc6115c CW |
762 | if (prefix) |
763 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 764 | |
5ac52f33 CW |
765 | avail = skb_tailroom(skb); |
766 | p = d_path(dentry, vfsmnt, skb->tail, avail); | |
1da177e4 LT |
767 | if (IS_ERR(p)) { |
768 | /* FIXME: can we save some information here? */ | |
769 | audit_log_format(ab, "<toolong>"); | |
770 | } else { | |
5ac52f33 CW |
771 | /* path isn't at start of buffer */ |
772 | len = ((char *)skb->tail + avail - 1) - p; | |
773 | memmove(skb->tail, p, len); | |
774 | skb_put(skb, len); | |
1da177e4 LT |
775 | } |
776 | } | |
777 | ||
23f32d18 | 778 | /* Remove queued messages from the audit_txlist and send them to user space. */ |
1da177e4 LT |
779 | static void audit_tasklet_handler(unsigned long arg) |
780 | { | |
781 | LIST_HEAD(list); | |
782 | struct audit_buffer *ab; | |
783 | unsigned long flags; | |
784 | ||
785 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
786 | list_splice_init(&audit_txlist, &list); | |
787 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
788 | ||
789 | while (!list_empty(&list)) { | |
790 | ab = list_entry(list.next, struct audit_buffer, list); | |
791 | list_del(&ab->list); | |
792 | audit_log_end_fast(ab); | |
793 | } | |
794 | } | |
795 | ||
796 | static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0); | |
797 | ||
798 | /* The netlink_* functions cannot be called inside an irq context, so | |
799 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
800 | * remove them from the queue outside the irq context. May be called in | |
801 | * any context. */ | |
802 | static void audit_log_end_irq(struct audit_buffer *ab) | |
803 | { | |
804 | unsigned long flags; | |
805 | ||
806 | if (!ab) | |
807 | return; | |
808 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
809 | list_add_tail(&ab->list, &audit_txlist); | |
810 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
811 | ||
812 | tasklet_schedule(&audit_tasklet); | |
813 | } | |
814 | ||
815 | /* Send the message in the audit buffer directly to user space. May not | |
816 | * be called in an irq context. */ | |
817 | static void audit_log_end_fast(struct audit_buffer *ab) | |
818 | { | |
1da177e4 LT |
819 | BUG_ON(in_irq()); |
820 | if (!ab) | |
821 | return; | |
822 | if (!audit_rate_check()) { | |
823 | audit_log_lost("rate limit exceeded"); | |
824 | } else { | |
1da177e4 LT |
825 | if (audit_log_drain(ab)) |
826 | return; | |
827 | } | |
16e1904e | 828 | audit_buffer_free(ab); |
1da177e4 LT |
829 | } |
830 | ||
831 | /* Send or queue the message in the audit buffer, depending on the | |
832 | * current context. (A convenience function that may be called in any | |
833 | * context.) */ | |
834 | void audit_log_end(struct audit_buffer *ab) | |
835 | { | |
836 | if (in_irq()) | |
837 | audit_log_end_irq(ab); | |
838 | else | |
839 | audit_log_end_fast(ab); | |
840 | } | |
841 | ||
842 | /* Log an audit record. This is a convenience function that calls | |
843 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
844 | * called in any context. */ | |
c0404993 | 845 | void audit_log(struct audit_context *ctx, int type, const char *fmt, ...) |
1da177e4 LT |
846 | { |
847 | struct audit_buffer *ab; | |
848 | va_list args; | |
849 | ||
c0404993 | 850 | ab = audit_log_start(ctx, type); |
1da177e4 LT |
851 | if (ab) { |
852 | va_start(args, fmt); | |
853 | audit_log_vformat(ab, fmt, args); | |
854 | va_end(args); | |
855 | audit_log_end(ab); | |
856 | } | |
857 | } |