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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 | ||
1da177e4 LT |
143 | struct audit_entry { |
144 | struct list_head list; | |
145 | struct audit_rule rule; | |
146 | }; | |
147 | ||
148 | static void audit_log_end_irq(struct audit_buffer *ab); | |
149 | static void audit_log_end_fast(struct audit_buffer *ab); | |
150 | ||
151 | static void audit_panic(const char *message) | |
152 | { | |
153 | switch (audit_failure) | |
154 | { | |
155 | case AUDIT_FAIL_SILENT: | |
156 | break; | |
157 | case AUDIT_FAIL_PRINTK: | |
158 | printk(KERN_ERR "audit: %s\n", message); | |
159 | break; | |
160 | case AUDIT_FAIL_PANIC: | |
161 | panic("audit: %s\n", message); | |
162 | break; | |
163 | } | |
164 | } | |
165 | ||
166 | static inline int audit_rate_check(void) | |
167 | { | |
168 | static unsigned long last_check = 0; | |
169 | static int messages = 0; | |
170 | static DEFINE_SPINLOCK(lock); | |
171 | unsigned long flags; | |
172 | unsigned long now; | |
173 | unsigned long elapsed; | |
174 | int retval = 0; | |
175 | ||
176 | if (!audit_rate_limit) return 1; | |
177 | ||
178 | spin_lock_irqsave(&lock, flags); | |
179 | if (++messages < audit_rate_limit) { | |
180 | retval = 1; | |
181 | } else { | |
182 | now = jiffies; | |
183 | elapsed = now - last_check; | |
184 | if (elapsed > HZ) { | |
185 | last_check = now; | |
186 | messages = 0; | |
187 | retval = 1; | |
188 | } | |
189 | } | |
190 | spin_unlock_irqrestore(&lock, flags); | |
191 | ||
192 | return retval; | |
193 | } | |
194 | ||
195 | /* Emit at least 1 message per second, even if audit_rate_check is | |
196 | * throttling. */ | |
197 | void audit_log_lost(const char *message) | |
198 | { | |
199 | static unsigned long last_msg = 0; | |
200 | static DEFINE_SPINLOCK(lock); | |
201 | unsigned long flags; | |
202 | unsigned long now; | |
203 | int print; | |
204 | ||
205 | atomic_inc(&audit_lost); | |
206 | ||
207 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
208 | ||
209 | if (!print) { | |
210 | spin_lock_irqsave(&lock, flags); | |
211 | now = jiffies; | |
212 | if (now - last_msg > HZ) { | |
213 | print = 1; | |
214 | last_msg = now; | |
215 | } | |
216 | spin_unlock_irqrestore(&lock, flags); | |
217 | } | |
218 | ||
219 | if (print) { | |
220 | printk(KERN_WARNING | |
221 | "audit: audit_lost=%d audit_backlog=%d" | |
222 | " audit_rate_limit=%d audit_backlog_limit=%d\n", | |
223 | atomic_read(&audit_lost), | |
224 | atomic_read(&audit_backlog), | |
225 | audit_rate_limit, | |
226 | audit_backlog_limit); | |
227 | audit_panic(message); | |
228 | } | |
229 | ||
230 | } | |
231 | ||
c94c257c | 232 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
233 | { |
234 | int old = audit_rate_limit; | |
235 | audit_rate_limit = limit; | |
c94c257c SH |
236 | audit_log(NULL, "audit_rate_limit=%d old=%d by auid %u", |
237 | audit_rate_limit, old, loginuid); | |
1da177e4 LT |
238 | return old; |
239 | } | |
240 | ||
c94c257c | 241 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
242 | { |
243 | int old = audit_backlog_limit; | |
244 | audit_backlog_limit = limit; | |
c94c257c SH |
245 | audit_log(NULL, "audit_backlog_limit=%d old=%d by auid %u", |
246 | audit_backlog_limit, old, loginuid); | |
1da177e4 LT |
247 | return old; |
248 | } | |
249 | ||
c94c257c | 250 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
251 | { |
252 | int old = audit_enabled; | |
253 | if (state != 0 && state != 1) | |
254 | return -EINVAL; | |
255 | audit_enabled = state; | |
c94c257c SH |
256 | audit_log(NULL, "audit_enabled=%d old=%d by auid %u", |
257 | audit_enabled, old, loginuid); | |
1da177e4 LT |
258 | return old; |
259 | } | |
260 | ||
c94c257c | 261 | static int audit_set_failure(int state, uid_t loginuid) |
1da177e4 LT |
262 | { |
263 | int old = audit_failure; | |
264 | if (state != AUDIT_FAIL_SILENT | |
265 | && state != AUDIT_FAIL_PRINTK | |
266 | && state != AUDIT_FAIL_PANIC) | |
267 | return -EINVAL; | |
268 | audit_failure = state; | |
c94c257c SH |
269 | audit_log(NULL, "audit_failure=%d old=%d by auid %u", |
270 | audit_failure, old, loginuid); | |
1da177e4 LT |
271 | return old; |
272 | } | |
273 | ||
1da177e4 LT |
274 | void audit_send_reply(int pid, int seq, int type, int done, int multi, |
275 | void *payload, int size) | |
276 | { | |
277 | struct sk_buff *skb; | |
278 | struct nlmsghdr *nlh; | |
279 | int len = NLMSG_SPACE(size); | |
280 | void *data; | |
281 | int flags = multi ? NLM_F_MULTI : 0; | |
282 | int t = done ? NLMSG_DONE : type; | |
283 | ||
284 | skb = alloc_skb(len, GFP_KERNEL); | |
285 | if (!skb) | |
286 | goto nlmsg_failure; | |
287 | ||
288 | nlh = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh)); | |
289 | nlh->nlmsg_flags = flags; | |
290 | data = NLMSG_DATA(nlh); | |
291 | memcpy(data, payload, size); | |
292 | netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT); | |
293 | return; | |
294 | ||
295 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
296 | if (skb) | |
297 | kfree_skb(skb); | |
298 | } | |
299 | ||
300 | /* | |
301 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
302 | * control messages. | |
303 | */ | |
304 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
305 | { | |
306 | int err = 0; | |
307 | ||
308 | switch (msg_type) { | |
309 | case AUDIT_GET: | |
310 | case AUDIT_LIST: | |
311 | case AUDIT_SET: | |
312 | case AUDIT_ADD: | |
313 | case AUDIT_DEL: | |
c2f0c7c3 | 314 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
315 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
316 | err = -EPERM; | |
317 | break; | |
318 | case AUDIT_USER: | |
319 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) | |
320 | err = -EPERM; | |
321 | break; | |
322 | default: /* bad msg */ | |
323 | err = -EINVAL; | |
324 | } | |
325 | ||
326 | return err; | |
327 | } | |
328 | ||
329 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
330 | { | |
331 | u32 uid, pid, seq; | |
332 | void *data; | |
333 | struct audit_status *status_get, status_set; | |
334 | int err; | |
1da177e4 | 335 | u16 msg_type = nlh->nlmsg_type; |
c94c257c | 336 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 337 | struct audit_sig_info sig_data; |
1da177e4 LT |
338 | |
339 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
340 | if (err) | |
341 | return err; | |
342 | ||
343 | pid = NETLINK_CREDS(skb)->pid; | |
344 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 345 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
346 | seq = nlh->nlmsg_seq; |
347 | data = NLMSG_DATA(nlh); | |
348 | ||
349 | switch (msg_type) { | |
350 | case AUDIT_GET: | |
351 | status_set.enabled = audit_enabled; | |
352 | status_set.failure = audit_failure; | |
353 | status_set.pid = audit_pid; | |
354 | status_set.rate_limit = audit_rate_limit; | |
355 | status_set.backlog_limit = audit_backlog_limit; | |
356 | status_set.lost = atomic_read(&audit_lost); | |
357 | status_set.backlog = atomic_read(&audit_backlog); | |
358 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, | |
359 | &status_set, sizeof(status_set)); | |
360 | break; | |
361 | case AUDIT_SET: | |
362 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
363 | return -EINVAL; | |
364 | status_get = (struct audit_status *)data; | |
365 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 366 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
367 | if (err < 0) return err; |
368 | } | |
369 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 370 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
371 | if (err < 0) return err; |
372 | } | |
373 | if (status_get->mask & AUDIT_STATUS_PID) { | |
374 | int old = audit_pid; | |
375 | audit_pid = status_get->pid; | |
c94c257c SH |
376 | audit_log(NULL, "audit_pid=%d old=%d by auid %u", |
377 | audit_pid, old, loginuid); | |
1da177e4 LT |
378 | } |
379 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 380 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 381 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
382 | audit_set_backlog_limit(status_get->backlog_limit, |
383 | loginuid); | |
1da177e4 LT |
384 | break; |
385 | case AUDIT_USER: | |
c1b773d8 | 386 | audit_log_type(NULL, AUDIT_USER, pid, |
c94c257c SH |
387 | "user pid=%d uid=%d length=%d loginuid=%u" |
388 | " msg='%.1024s'", | |
1da177e4 LT |
389 | pid, uid, |
390 | (int)(nlh->nlmsg_len | |
391 | - ((char *)data - (char *)nlh)), | |
c94c257c | 392 | loginuid, (char *)data); |
1da177e4 LT |
393 | break; |
394 | case AUDIT_ADD: | |
395 | case AUDIT_DEL: | |
396 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
397 | return -EINVAL; | |
398 | /* fallthrough */ | |
399 | case AUDIT_LIST: | |
1da177e4 | 400 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, |
c94c257c | 401 | uid, seq, data, loginuid); |
1da177e4 | 402 | break; |
c2f0c7c3 SG |
403 | case AUDIT_SIGNAL_INFO: |
404 | sig_data.uid = audit_sig_uid; | |
405 | sig_data.pid = audit_sig_pid; | |
406 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
407 | 0, 0, &sig_data, sizeof(sig_data)); | |
408 | break; | |
1da177e4 LT |
409 | default: |
410 | err = -EINVAL; | |
411 | break; | |
412 | } | |
413 | ||
414 | return err < 0 ? err : 0; | |
415 | } | |
416 | ||
417 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
418 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
419 | * discarded silently. */ | |
2a0a6ebe | 420 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
421 | { |
422 | int err; | |
423 | struct nlmsghdr *nlh; | |
424 | u32 rlen; | |
425 | ||
426 | while (skb->len >= NLMSG_SPACE(0)) { | |
427 | nlh = (struct nlmsghdr *)skb->data; | |
428 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 429 | return; |
1da177e4 LT |
430 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
431 | if (rlen > skb->len) | |
432 | rlen = skb->len; | |
433 | if ((err = audit_receive_msg(skb, nlh))) { | |
434 | netlink_ack(skb, nlh, err); | |
435 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
436 | netlink_ack(skb, nlh, 0); | |
437 | skb_pull(skb, rlen); | |
438 | } | |
1da177e4 LT |
439 | } |
440 | ||
441 | /* Receive messages from netlink socket. */ | |
442 | static void audit_receive(struct sock *sk, int length) | |
443 | { | |
444 | struct sk_buff *skb; | |
2a0a6ebe | 445 | unsigned int qlen; |
1da177e4 | 446 | |
2a0a6ebe | 447 | down(&audit_netlink_sem); |
1da177e4 | 448 | |
2a0a6ebe HX |
449 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
450 | skb = skb_dequeue(&sk->sk_receive_queue); | |
451 | audit_receive_skb(skb); | |
452 | kfree_skb(skb); | |
1da177e4 LT |
453 | } |
454 | up(&audit_netlink_sem); | |
455 | } | |
456 | ||
5ac52f33 | 457 | /* Grab skbuff from the audit_buffer and send to user space. */ |
1da177e4 LT |
458 | static inline int audit_log_drain(struct audit_buffer *ab) |
459 | { | |
8fc6115c | 460 | struct sk_buff *skb = ab->skb; |
1da177e4 | 461 | |
8fc6115c | 462 | if (skb) { |
1da177e4 LT |
463 | int retval = 0; |
464 | ||
465 | if (audit_pid) { | |
5ac52f33 | 466 | struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data; |
5a241d77 | 467 | nlh->nlmsg_len = skb->len - NLMSG_SPACE(0); |
1da177e4 LT |
468 | skb_get(skb); /* because netlink_* frees */ |
469 | retval = netlink_unicast(audit_sock, skb, audit_pid, | |
470 | MSG_DONTWAIT); | |
471 | } | |
37509e74 CW |
472 | if (retval == -EAGAIN && |
473 | (atomic_read(&audit_backlog)) < audit_backlog_limit) { | |
1da177e4 LT |
474 | audit_log_end_irq(ab); |
475 | return 1; | |
476 | } | |
477 | if (retval < 0) { | |
478 | if (retval == -ECONNREFUSED) { | |
479 | printk(KERN_ERR | |
480 | "audit: *NO* daemon at audit_pid=%d\n", | |
481 | audit_pid); | |
482 | audit_pid = 0; | |
483 | } else | |
484 | audit_log_lost("netlink socket too busy"); | |
485 | } | |
486 | if (!audit_pid) { /* No daemon */ | |
8fc6115c | 487 | int offset = NLMSG_SPACE(0); |
1da177e4 | 488 | int len = skb->len - offset; |
c7fcb0ee PM |
489 | skb->data[offset + len] = '\0'; |
490 | printk(KERN_ERR "%s\n", skb->data + offset); | |
1da177e4 | 491 | } |
1da177e4 LT |
492 | } |
493 | return 0; | |
494 | } | |
495 | ||
496 | /* Initialize audit support at boot time. */ | |
497 | static int __init audit_init(void) | |
498 | { | |
499 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
500 | audit_default ? "enabled" : "disabled"); | |
501 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
502 | if (!audit_sock) | |
503 | audit_panic("cannot initialize netlink socket"); | |
504 | ||
505 | audit_initialized = 1; | |
506 | audit_enabled = audit_default; | |
507 | audit_log(NULL, "initialized"); | |
508 | return 0; | |
509 | } | |
1da177e4 LT |
510 | __initcall(audit_init); |
511 | ||
512 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
513 | static int __init audit_enable(char *str) | |
514 | { | |
515 | audit_default = !!simple_strtol(str, NULL, 0); | |
516 | printk(KERN_INFO "audit: %s%s\n", | |
517 | audit_default ? "enabled" : "disabled", | |
518 | audit_initialized ? "" : " (after initialization)"); | |
519 | if (audit_initialized) | |
520 | audit_enabled = audit_default; | |
521 | return 0; | |
522 | } | |
523 | ||
524 | __setup("audit=", audit_enable); | |
525 | ||
16e1904e CW |
526 | static void audit_buffer_free(struct audit_buffer *ab) |
527 | { | |
528 | unsigned long flags; | |
529 | ||
8fc6115c CW |
530 | if (!ab) |
531 | return; | |
532 | ||
5ac52f33 CW |
533 | if (ab->skb) |
534 | kfree_skb(ab->skb); | |
16e1904e CW |
535 | atomic_dec(&audit_backlog); |
536 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
537 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
538 | kfree(ab); | |
539 | else | |
540 | list_add(&ab->list, &audit_freelist); | |
541 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
542 | } | |
543 | ||
c1b773d8 | 544 | static struct audit_buffer * audit_buffer_alloc(int gfp_mask) |
16e1904e CW |
545 | { |
546 | unsigned long flags; | |
547 | struct audit_buffer *ab = NULL; | |
548 | ||
549 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
550 | if (!list_empty(&audit_freelist)) { | |
551 | ab = list_entry(audit_freelist.next, | |
552 | struct audit_buffer, list); | |
553 | list_del(&ab->list); | |
554 | --audit_freelist_count; | |
555 | } | |
556 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
557 | ||
558 | if (!ab) { | |
4332bdd3 | 559 | ab = kmalloc(sizeof(*ab), gfp_mask); |
16e1904e | 560 | if (!ab) |
8fc6115c | 561 | goto err; |
16e1904e CW |
562 | } |
563 | atomic_inc(&audit_backlog); | |
8fc6115c | 564 | |
4332bdd3 | 565 | ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); |
5ac52f33 | 566 | if (!ab->skb) |
8fc6115c CW |
567 | goto err; |
568 | ||
16e1904e | 569 | return ab; |
8fc6115c CW |
570 | err: |
571 | audit_buffer_free(ab); | |
572 | return NULL; | |
16e1904e | 573 | } |
1da177e4 LT |
574 | |
575 | /* Obtain an audit buffer. This routine does locking to obtain the | |
576 | * audit buffer, but then no locking is required for calls to | |
577 | * audit_log_*format. If the tsk is a task that is currently in a | |
578 | * syscall, then the syscall is marked as auditable and an audit record | |
579 | * will be written at syscall exit. If there is no associated task, tsk | |
580 | * should be NULL. */ | |
c1b773d8 | 581 | struct audit_buffer *audit_log_start(struct audit_context *ctx, int type, int pid) |
1da177e4 LT |
582 | { |
583 | struct audit_buffer *ab = NULL; | |
1da177e4 | 584 | struct timespec t; |
d812ddbb | 585 | unsigned int serial; |
c1b773d8 | 586 | struct nlmsghdr *nlh; |
1da177e4 LT |
587 | |
588 | if (!audit_initialized) | |
589 | return NULL; | |
590 | ||
591 | if (audit_backlog_limit | |
592 | && atomic_read(&audit_backlog) > audit_backlog_limit) { | |
593 | if (audit_rate_check()) | |
594 | printk(KERN_WARNING | |
595 | "audit: audit_backlog=%d > " | |
596 | "audit_backlog_limit=%d\n", | |
597 | atomic_read(&audit_backlog), | |
598 | audit_backlog_limit); | |
599 | audit_log_lost("backlog limit exceeded"); | |
600 | return NULL; | |
601 | } | |
602 | ||
c1b773d8 | 603 | ab = audit_buffer_alloc(GFP_ATOMIC); |
1da177e4 LT |
604 | if (!ab) { |
605 | audit_log_lost("out of memory in audit_log_start"); | |
606 | return NULL; | |
607 | } | |
608 | ||
c1b773d8 CW |
609 | ab->ctx = ctx; |
610 | nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); | |
611 | nlh->nlmsg_type = type; | |
612 | nlh->nlmsg_flags = 0; | |
613 | nlh->nlmsg_pid = pid; | |
614 | nlh->nlmsg_seq = 0; | |
615 | ||
197c69c6 | 616 | if (!audit_get_stamp(ab->ctx, &t, &serial)) { |
1da177e4 | 617 | t = CURRENT_TIME; |
d812ddbb SG |
618 | serial = 0; |
619 | } | |
197c69c6 | 620 | |
1da177e4 LT |
621 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
622 | t.tv_sec, t.tv_nsec/1000000, serial); | |
623 | return ab; | |
624 | } | |
625 | ||
8fc6115c | 626 | /** |
5ac52f33 | 627 | * audit_expand - expand skb in the audit buffer |
8fc6115c CW |
628 | * @ab: audit_buffer |
629 | * | |
630 | * Returns 0 (no space) on failed expansion, or available space if | |
631 | * successful. | |
632 | */ | |
e3b926b4 | 633 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
8fc6115c | 634 | { |
5ac52f33 | 635 | struct sk_buff *skb = ab->skb; |
e3b926b4 | 636 | int ret = pskb_expand_head(skb, skb_headroom(skb), extra, |
5ac52f33 CW |
637 | GFP_ATOMIC); |
638 | if (ret < 0) { | |
639 | audit_log_lost("out of memory in audit_expand"); | |
8fc6115c | 640 | return 0; |
5ac52f33 CW |
641 | } |
642 | return skb_tailroom(skb); | |
8fc6115c | 643 | } |
1da177e4 LT |
644 | |
645 | /* Format an audit message into the audit buffer. If there isn't enough | |
646 | * room in the audit buffer, more room will be allocated and vsnprint | |
647 | * will be called a second time. Currently, we assume that a printk | |
648 | * can't format message larger than 1024 bytes, so we don't either. */ | |
649 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
650 | va_list args) | |
651 | { | |
652 | int len, avail; | |
5ac52f33 | 653 | struct sk_buff *skb; |
eecb0a73 | 654 | va_list args2; |
1da177e4 LT |
655 | |
656 | if (!ab) | |
657 | return; | |
658 | ||
5ac52f33 CW |
659 | BUG_ON(!ab->skb); |
660 | skb = ab->skb; | |
661 | avail = skb_tailroom(skb); | |
662 | if (avail == 0) { | |
e3b926b4 | 663 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
8fc6115c CW |
664 | if (!avail) |
665 | goto out; | |
1da177e4 | 666 | } |
eecb0a73 | 667 | va_copy(args2, args); |
5ac52f33 | 668 | len = vsnprintf(skb->tail, avail, fmt, args); |
1da177e4 LT |
669 | if (len >= avail) { |
670 | /* The printk buffer is 1024 bytes long, so if we get | |
671 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
672 | * log everything that printk could have logged. */ | |
9ea74f06 | 673 | avail = audit_expand(ab, max_t(AUDIT_BUFSIZ, 1+len-avail)); |
8fc6115c CW |
674 | if (!avail) |
675 | goto out; | |
eecb0a73 | 676 | len = vsnprintf(skb->tail, avail, fmt, args2); |
1da177e4 | 677 | } |
5ac52f33 | 678 | skb_put(skb, (len < avail) ? len : avail); |
8fc6115c CW |
679 | out: |
680 | return; | |
1da177e4 LT |
681 | } |
682 | ||
683 | /* Format a message into the audit buffer. All the work is done in | |
684 | * audit_log_vformat. */ | |
685 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
686 | { | |
687 | va_list args; | |
688 | ||
689 | if (!ab) | |
690 | return; | |
691 | va_start(args, fmt); | |
692 | audit_log_vformat(ab, fmt, args); | |
693 | va_end(args); | |
694 | } | |
695 | ||
83c7d091 DW |
696 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len) |
697 | { | |
698 | int i; | |
699 | ||
700 | for (i=0; i<len; i++) | |
701 | audit_log_format(ab, "%02x", buf[i]); | |
702 | } | |
703 | ||
704 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) | |
705 | { | |
81b7854d | 706 | const unsigned char *p = string; |
83c7d091 DW |
707 | |
708 | while (*p) { | |
709 | if (*p == '"' || *p == ' ' || *p < 0x20 || *p > 0x7f) { | |
710 | audit_log_hex(ab, string, strlen(string)); | |
711 | return; | |
712 | } | |
713 | p++; | |
714 | } | |
715 | audit_log_format(ab, "\"%s\"", string); | |
716 | } | |
717 | ||
718 | ||
1da177e4 LT |
719 | /* This is a helper-function to print the d_path without using a static |
720 | * buffer or allocating another buffer in addition to the one in | |
721 | * audit_buffer. */ | |
722 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, | |
723 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
724 | { | |
725 | char *p; | |
5ac52f33 | 726 | struct sk_buff *skb = ab->skb; |
1da177e4 LT |
727 | int len, avail; |
728 | ||
8fc6115c CW |
729 | if (prefix) |
730 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 731 | |
5ac52f33 CW |
732 | avail = skb_tailroom(skb); |
733 | p = d_path(dentry, vfsmnt, skb->tail, avail); | |
1da177e4 LT |
734 | if (IS_ERR(p)) { |
735 | /* FIXME: can we save some information here? */ | |
736 | audit_log_format(ab, "<toolong>"); | |
737 | } else { | |
5ac52f33 CW |
738 | /* path isn't at start of buffer */ |
739 | len = ((char *)skb->tail + avail - 1) - p; | |
740 | memmove(skb->tail, p, len); | |
741 | skb_put(skb, len); | |
1da177e4 LT |
742 | } |
743 | } | |
744 | ||
745 | /* Remove queued messages from the audit_txlist and send them to userspace. */ | |
746 | static void audit_tasklet_handler(unsigned long arg) | |
747 | { | |
748 | LIST_HEAD(list); | |
749 | struct audit_buffer *ab; | |
750 | unsigned long flags; | |
751 | ||
752 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
753 | list_splice_init(&audit_txlist, &list); | |
754 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
755 | ||
756 | while (!list_empty(&list)) { | |
757 | ab = list_entry(list.next, struct audit_buffer, list); | |
758 | list_del(&ab->list); | |
759 | audit_log_end_fast(ab); | |
760 | } | |
761 | } | |
762 | ||
763 | static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0); | |
764 | ||
765 | /* The netlink_* functions cannot be called inside an irq context, so | |
766 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
767 | * remove them from the queue outside the irq context. May be called in | |
768 | * any context. */ | |
769 | static void audit_log_end_irq(struct audit_buffer *ab) | |
770 | { | |
771 | unsigned long flags; | |
772 | ||
773 | if (!ab) | |
774 | return; | |
775 | spin_lock_irqsave(&audit_txlist_lock, flags); | |
776 | list_add_tail(&ab->list, &audit_txlist); | |
777 | spin_unlock_irqrestore(&audit_txlist_lock, flags); | |
778 | ||
779 | tasklet_schedule(&audit_tasklet); | |
780 | } | |
781 | ||
782 | /* Send the message in the audit buffer directly to user space. May not | |
783 | * be called in an irq context. */ | |
784 | static void audit_log_end_fast(struct audit_buffer *ab) | |
785 | { | |
1da177e4 LT |
786 | BUG_ON(in_irq()); |
787 | if (!ab) | |
788 | return; | |
789 | if (!audit_rate_check()) { | |
790 | audit_log_lost("rate limit exceeded"); | |
791 | } else { | |
1da177e4 LT |
792 | if (audit_log_drain(ab)) |
793 | return; | |
794 | } | |
16e1904e | 795 | audit_buffer_free(ab); |
1da177e4 LT |
796 | } |
797 | ||
798 | /* Send or queue the message in the audit buffer, depending on the | |
799 | * current context. (A convenience function that may be called in any | |
800 | * context.) */ | |
801 | void audit_log_end(struct audit_buffer *ab) | |
802 | { | |
803 | if (in_irq()) | |
804 | audit_log_end_irq(ab); | |
805 | else | |
806 | audit_log_end_fast(ab); | |
807 | } | |
808 | ||
809 | /* Log an audit record. This is a convenience function that calls | |
810 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
811 | * called in any context. */ | |
c1b773d8 CW |
812 | void audit_log_type(struct audit_context *ctx, int type, int pid, |
813 | const char *fmt, ...) | |
1da177e4 LT |
814 | { |
815 | struct audit_buffer *ab; | |
816 | va_list args; | |
817 | ||
c1b773d8 | 818 | ab = audit_log_start(ctx, type, pid); |
1da177e4 LT |
819 | if (ab) { |
820 | va_start(args, fmt); | |
821 | audit_log_vformat(ab, fmt, args); | |
822 | va_end(args); | |
823 | audit_log_end(ab); | |
824 | } | |
825 | } |