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> | |
b7d11258 DW |
49 | #include <linux/err.h> |
50 | #include <linux/kthread.h> | |
1da177e4 LT |
51 | |
52 | #include <linux/audit.h> | |
53 | ||
54 | #include <net/sock.h> | |
55 | #include <linux/skbuff.h> | |
56 | #include <linux/netlink.h> | |
57 | ||
58 | /* No auditing will take place until audit_initialized != 0. | |
59 | * (Initialization happens after skb_init is called.) */ | |
60 | static int audit_initialized; | |
61 | ||
62 | /* No syscall auditing will take place unless audit_enabled != 0. */ | |
63 | int audit_enabled; | |
64 | ||
65 | /* Default state when kernel boots without any parameters. */ | |
66 | static int audit_default; | |
67 | ||
68 | /* If auditing cannot proceed, audit_failure selects what happens. */ | |
69 | static int audit_failure = AUDIT_FAIL_PRINTK; | |
70 | ||
71 | /* If audit records are to be written to the netlink socket, audit_pid | |
72 | * contains the (non-zero) pid. */ | |
c2f0c7c3 | 73 | int audit_pid; |
1da177e4 LT |
74 | |
75 | /* If audit_limit is non-zero, limit the rate of sending audit records | |
76 | * to that number per second. This prevents DoS attacks, but results in | |
77 | * audit records being dropped. */ | |
78 | static int audit_rate_limit; | |
79 | ||
80 | /* Number of outstanding audit_buffers allowed. */ | |
81 | static int audit_backlog_limit = 64; | |
1da177e4 | 82 | |
c2f0c7c3 SG |
83 | /* The identity of the user shutting down the audit system. */ |
84 | uid_t audit_sig_uid = -1; | |
85 | pid_t audit_sig_pid = -1; | |
86 | ||
1da177e4 LT |
87 | /* Records can be lost in several ways: |
88 | 0) [suppressed in audit_alloc] | |
89 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] | |
90 | 2) out of memory in audit_log_move [alloc_skb] | |
91 | 3) suppressed due to audit_rate_limit | |
92 | 4) suppressed due to audit_backlog_limit | |
93 | */ | |
94 | static atomic_t audit_lost = ATOMIC_INIT(0); | |
95 | ||
96 | /* The netlink socket. */ | |
97 | static struct sock *audit_sock; | |
98 | ||
b7d11258 | 99 | /* The audit_freelist is a list of pre-allocated audit buffers (if more |
1da177e4 LT |
100 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of |
101 | * being placed on the freelist). */ | |
1da177e4 LT |
102 | static DEFINE_SPINLOCK(audit_freelist_lock); |
103 | static int audit_freelist_count = 0; | |
1da177e4 LT |
104 | static LIST_HEAD(audit_freelist); |
105 | ||
b7d11258 DW |
106 | static struct sk_buff_head audit_skb_queue; |
107 | static struct task_struct *kauditd_task; | |
108 | static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); | |
109 | ||
1da177e4 | 110 | /* The netlink socket is only to be read by 1 CPU, which lets us assume |
23f32d18 | 111 | * that list additions and deletions never happen simultaneously in |
1da177e4 LT |
112 | * auditsc.c */ |
113 | static DECLARE_MUTEX(audit_netlink_sem); | |
114 | ||
115 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
116 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
117 | * should be at least that large. */ | |
118 | #define AUDIT_BUFSIZ 1024 | |
119 | ||
120 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
121 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
122 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
123 | ||
124 | /* The audit_buffer is used when formatting an audit record. The caller | |
125 | * locks briefly to get the record off the freelist or to allocate the | |
126 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
127 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
128 | * use simultaneously. */ | |
129 | struct audit_buffer { | |
130 | struct list_head list; | |
8fc6115c | 131 | struct sk_buff *skb; /* formatted skb ready to send */ |
1da177e4 | 132 | struct audit_context *ctx; /* NULL or associated context */ |
1da177e4 LT |
133 | }; |
134 | ||
c0404993 SG |
135 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
136 | { | |
137 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
138 | nlh->nlmsg_pid = pid; | |
139 | } | |
140 | ||
1da177e4 LT |
141 | struct audit_entry { |
142 | struct list_head list; | |
143 | struct audit_rule rule; | |
144 | }; | |
145 | ||
1da177e4 LT |
146 | static void audit_panic(const char *message) |
147 | { | |
148 | switch (audit_failure) | |
149 | { | |
150 | case AUDIT_FAIL_SILENT: | |
151 | break; | |
152 | case AUDIT_FAIL_PRINTK: | |
153 | printk(KERN_ERR "audit: %s\n", message); | |
154 | break; | |
155 | case AUDIT_FAIL_PANIC: | |
156 | panic("audit: %s\n", message); | |
157 | break; | |
158 | } | |
159 | } | |
160 | ||
161 | static inline int audit_rate_check(void) | |
162 | { | |
163 | static unsigned long last_check = 0; | |
164 | static int messages = 0; | |
165 | static DEFINE_SPINLOCK(lock); | |
166 | unsigned long flags; | |
167 | unsigned long now; | |
168 | unsigned long elapsed; | |
169 | int retval = 0; | |
170 | ||
171 | if (!audit_rate_limit) return 1; | |
172 | ||
173 | spin_lock_irqsave(&lock, flags); | |
174 | if (++messages < audit_rate_limit) { | |
175 | retval = 1; | |
176 | } else { | |
177 | now = jiffies; | |
178 | elapsed = now - last_check; | |
179 | if (elapsed > HZ) { | |
180 | last_check = now; | |
181 | messages = 0; | |
182 | retval = 1; | |
183 | } | |
184 | } | |
185 | spin_unlock_irqrestore(&lock, flags); | |
186 | ||
187 | return retval; | |
188 | } | |
189 | ||
190 | /* Emit at least 1 message per second, even if audit_rate_check is | |
191 | * throttling. */ | |
192 | void audit_log_lost(const char *message) | |
193 | { | |
194 | static unsigned long last_msg = 0; | |
195 | static DEFINE_SPINLOCK(lock); | |
196 | unsigned long flags; | |
197 | unsigned long now; | |
198 | int print; | |
199 | ||
200 | atomic_inc(&audit_lost); | |
201 | ||
202 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
203 | ||
204 | if (!print) { | |
205 | spin_lock_irqsave(&lock, flags); | |
206 | now = jiffies; | |
207 | if (now - last_msg > HZ) { | |
208 | print = 1; | |
209 | last_msg = now; | |
210 | } | |
211 | spin_unlock_irqrestore(&lock, flags); | |
212 | } | |
213 | ||
214 | if (print) { | |
215 | printk(KERN_WARNING | |
b7d11258 | 216 | "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n", |
1da177e4 | 217 | atomic_read(&audit_lost), |
1da177e4 LT |
218 | audit_rate_limit, |
219 | audit_backlog_limit); | |
220 | audit_panic(message); | |
221 | } | |
222 | ||
223 | } | |
224 | ||
c94c257c | 225 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
226 | { |
227 | int old = audit_rate_limit; | |
228 | audit_rate_limit = limit; | |
c0404993 | 229 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 230 | "audit_rate_limit=%d old=%d by auid=%u", |
c94c257c | 231 | audit_rate_limit, old, loginuid); |
1da177e4 LT |
232 | return old; |
233 | } | |
234 | ||
c94c257c | 235 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
236 | { |
237 | int old = audit_backlog_limit; | |
238 | audit_backlog_limit = limit; | |
c0404993 | 239 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 240 | "audit_backlog_limit=%d old=%d by auid=%u", |
c94c257c | 241 | audit_backlog_limit, old, loginuid); |
1da177e4 LT |
242 | return old; |
243 | } | |
244 | ||
c94c257c | 245 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
246 | { |
247 | int old = audit_enabled; | |
248 | if (state != 0 && state != 1) | |
249 | return -EINVAL; | |
250 | audit_enabled = state; | |
c0404993 | 251 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 252 | "audit_enabled=%d old=%d by auid=%u", |
c0404993 | 253 | audit_enabled, old, loginuid); |
1da177e4 LT |
254 | return old; |
255 | } | |
256 | ||
c94c257c | 257 | static int audit_set_failure(int state, uid_t loginuid) |
1da177e4 LT |
258 | { |
259 | int old = audit_failure; | |
260 | if (state != AUDIT_FAIL_SILENT | |
261 | && state != AUDIT_FAIL_PRINTK | |
262 | && state != AUDIT_FAIL_PANIC) | |
263 | return -EINVAL; | |
264 | audit_failure = state; | |
c0404993 | 265 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 266 | "audit_failure=%d old=%d by auid=%u", |
c0404993 | 267 | audit_failure, old, loginuid); |
1da177e4 LT |
268 | return old; |
269 | } | |
270 | ||
b7d11258 DW |
271 | int kauditd_thread(void *dummy) |
272 | { | |
273 | struct sk_buff *skb; | |
274 | ||
275 | while (1) { | |
276 | skb = skb_dequeue(&audit_skb_queue); | |
277 | if (skb) { | |
278 | if (audit_pid) { | |
279 | int err = netlink_unicast(audit_sock, skb, audit_pid, 0); | |
280 | if (err < 0) { | |
281 | BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */ | |
282 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); | |
283 | audit_pid = 0; | |
284 | } | |
285 | } else { | |
286 | printk(KERN_ERR "%s\n", skb->data + NLMSG_SPACE(0)); | |
287 | kfree_skb(skb); | |
288 | } | |
289 | } else { | |
290 | DECLARE_WAITQUEUE(wait, current); | |
291 | set_current_state(TASK_INTERRUPTIBLE); | |
292 | add_wait_queue(&kauditd_wait, &wait); | |
293 | ||
294 | if (!skb_queue_len(&audit_skb_queue)) | |
295 | schedule(); | |
296 | ||
297 | __set_current_state(TASK_RUNNING); | |
298 | remove_wait_queue(&kauditd_wait, &wait); | |
299 | } | |
300 | } | |
301 | } | |
302 | ||
1da177e4 LT |
303 | void audit_send_reply(int pid, int seq, int type, int done, int multi, |
304 | void *payload, int size) | |
305 | { | |
306 | struct sk_buff *skb; | |
307 | struct nlmsghdr *nlh; | |
308 | int len = NLMSG_SPACE(size); | |
309 | void *data; | |
310 | int flags = multi ? NLM_F_MULTI : 0; | |
311 | int t = done ? NLMSG_DONE : type; | |
312 | ||
313 | skb = alloc_skb(len, GFP_KERNEL); | |
314 | if (!skb) | |
b7d11258 | 315 | return; |
1da177e4 | 316 | |
b7d11258 | 317 | nlh = NLMSG_PUT(skb, pid, seq, t, size); |
1da177e4 LT |
318 | nlh->nlmsg_flags = flags; |
319 | data = NLMSG_DATA(nlh); | |
320 | memcpy(data, payload, size); | |
b7d11258 DW |
321 | |
322 | /* Ignore failure. It'll only happen if the sender goes away, | |
323 | because our timeout is set to infinite. */ | |
324 | netlink_unicast(audit_sock, skb, pid, 0); | |
1da177e4 LT |
325 | return; |
326 | ||
327 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
328 | if (skb) | |
329 | kfree_skb(skb); | |
330 | } | |
331 | ||
332 | /* | |
333 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
334 | * control messages. | |
335 | */ | |
336 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
337 | { | |
338 | int err = 0; | |
339 | ||
340 | switch (msg_type) { | |
341 | case AUDIT_GET: | |
342 | case AUDIT_LIST: | |
343 | case AUDIT_SET: | |
344 | case AUDIT_ADD: | |
345 | case AUDIT_DEL: | |
c2f0c7c3 | 346 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
347 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
348 | err = -EPERM; | |
349 | break; | |
05474106 | 350 | case AUDIT_USER: |
209aba03 | 351 | case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG: |
1da177e4 LT |
352 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) |
353 | err = -EPERM; | |
354 | break; | |
355 | default: /* bad msg */ | |
356 | err = -EINVAL; | |
357 | } | |
358 | ||
359 | return err; | |
360 | } | |
361 | ||
362 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
363 | { | |
364 | u32 uid, pid, seq; | |
365 | void *data; | |
366 | struct audit_status *status_get, status_set; | |
367 | int err; | |
c0404993 | 368 | struct audit_buffer *ab; |
1da177e4 | 369 | u16 msg_type = nlh->nlmsg_type; |
c94c257c | 370 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 371 | struct audit_sig_info sig_data; |
0f45aa18 | 372 | struct task_struct *tsk; |
1da177e4 LT |
373 | |
374 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
375 | if (err) | |
376 | return err; | |
377 | ||
b7d11258 DW |
378 | /* As soon as there's any sign of userspace auditd, start kauditd to talk to it */ |
379 | if (!kauditd_task) | |
380 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); | |
381 | if (IS_ERR(kauditd_task)) { | |
382 | err = PTR_ERR(kauditd_task); | |
383 | kauditd_task = NULL; | |
384 | return err; | |
385 | } | |
386 | ||
1da177e4 LT |
387 | pid = NETLINK_CREDS(skb)->pid; |
388 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 389 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
390 | seq = nlh->nlmsg_seq; |
391 | data = NLMSG_DATA(nlh); | |
392 | ||
393 | switch (msg_type) { | |
394 | case AUDIT_GET: | |
395 | status_set.enabled = audit_enabled; | |
396 | status_set.failure = audit_failure; | |
397 | status_set.pid = audit_pid; | |
398 | status_set.rate_limit = audit_rate_limit; | |
399 | status_set.backlog_limit = audit_backlog_limit; | |
400 | status_set.lost = atomic_read(&audit_lost); | |
b7d11258 | 401 | status_set.backlog = skb_queue_len(&audit_skb_queue); |
1da177e4 LT |
402 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, |
403 | &status_set, sizeof(status_set)); | |
404 | break; | |
405 | case AUDIT_SET: | |
406 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
407 | return -EINVAL; | |
408 | status_get = (struct audit_status *)data; | |
409 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 410 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
411 | if (err < 0) return err; |
412 | } | |
413 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 414 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
415 | if (err < 0) return err; |
416 | } | |
417 | if (status_get->mask & AUDIT_STATUS_PID) { | |
418 | int old = audit_pid; | |
419 | audit_pid = status_get->pid; | |
c0404993 | 420 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 421 | "audit_pid=%d old=%d by auid=%u", |
c94c257c | 422 | audit_pid, old, loginuid); |
1da177e4 LT |
423 | } |
424 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 425 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 426 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
427 | audit_set_backlog_limit(status_get->backlog_limit, |
428 | loginuid); | |
1da177e4 | 429 | break; |
05474106 | 430 | case AUDIT_USER: |
209aba03 | 431 | case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG: |
0f45aa18 DW |
432 | read_lock(&tasklist_lock); |
433 | tsk = find_task_by_pid(pid); | |
434 | if (tsk) | |
435 | get_task_struct(tsk); | |
436 | read_unlock(&tasklist_lock); | |
437 | if (!tsk) | |
438 | return -ESRCH; | |
439 | ||
d6e0e158 | 440 | if (audit_enabled && audit_filter_user(tsk, msg_type)) { |
0f45aa18 DW |
441 | ab = audit_log_start(NULL, msg_type); |
442 | if (ab) { | |
443 | audit_log_format(ab, | |
444 | "user pid=%d uid=%u auid=%u msg='%.1024s'", | |
445 | pid, uid, loginuid, (char *)data); | |
446 | audit_set_pid(ab, pid); | |
447 | audit_log_end(ab); | |
448 | } | |
449 | } | |
450 | put_task_struct(tsk); | |
1da177e4 LT |
451 | break; |
452 | case AUDIT_ADD: | |
453 | case AUDIT_DEL: | |
454 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
455 | return -EINVAL; | |
456 | /* fallthrough */ | |
457 | case AUDIT_LIST: | |
1da177e4 | 458 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, |
c94c257c | 459 | uid, seq, data, loginuid); |
1da177e4 | 460 | break; |
c2f0c7c3 SG |
461 | case AUDIT_SIGNAL_INFO: |
462 | sig_data.uid = audit_sig_uid; | |
463 | sig_data.pid = audit_sig_pid; | |
464 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
465 | 0, 0, &sig_data, sizeof(sig_data)); | |
466 | break; | |
1da177e4 LT |
467 | default: |
468 | err = -EINVAL; | |
469 | break; | |
470 | } | |
471 | ||
472 | return err < 0 ? err : 0; | |
473 | } | |
474 | ||
475 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
476 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
477 | * discarded silently. */ | |
2a0a6ebe | 478 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
479 | { |
480 | int err; | |
481 | struct nlmsghdr *nlh; | |
482 | u32 rlen; | |
483 | ||
484 | while (skb->len >= NLMSG_SPACE(0)) { | |
485 | nlh = (struct nlmsghdr *)skb->data; | |
486 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 487 | return; |
1da177e4 LT |
488 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
489 | if (rlen > skb->len) | |
490 | rlen = skb->len; | |
491 | if ((err = audit_receive_msg(skb, nlh))) { | |
492 | netlink_ack(skb, nlh, err); | |
493 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
494 | netlink_ack(skb, nlh, 0); | |
495 | skb_pull(skb, rlen); | |
496 | } | |
1da177e4 LT |
497 | } |
498 | ||
499 | /* Receive messages from netlink socket. */ | |
500 | static void audit_receive(struct sock *sk, int length) | |
501 | { | |
502 | struct sk_buff *skb; | |
2a0a6ebe | 503 | unsigned int qlen; |
1da177e4 | 504 | |
2a0a6ebe | 505 | down(&audit_netlink_sem); |
1da177e4 | 506 | |
2a0a6ebe HX |
507 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
508 | skb = skb_dequeue(&sk->sk_receive_queue); | |
509 | audit_receive_skb(skb); | |
510 | kfree_skb(skb); | |
1da177e4 LT |
511 | } |
512 | up(&audit_netlink_sem); | |
513 | } | |
514 | ||
1da177e4 LT |
515 | |
516 | /* Initialize audit support at boot time. */ | |
517 | static int __init audit_init(void) | |
518 | { | |
519 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
520 | audit_default ? "enabled" : "disabled"); | |
521 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive); | |
522 | if (!audit_sock) | |
523 | audit_panic("cannot initialize netlink socket"); | |
524 | ||
b7d11258 DW |
525 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; |
526 | skb_queue_head_init(&audit_skb_queue); | |
1da177e4 LT |
527 | audit_initialized = 1; |
528 | audit_enabled = audit_default; | |
c0404993 | 529 | audit_log(NULL, AUDIT_KERNEL, "initialized"); |
1da177e4 LT |
530 | return 0; |
531 | } | |
1da177e4 LT |
532 | __initcall(audit_init); |
533 | ||
534 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
535 | static int __init audit_enable(char *str) | |
536 | { | |
537 | audit_default = !!simple_strtol(str, NULL, 0); | |
538 | printk(KERN_INFO "audit: %s%s\n", | |
539 | audit_default ? "enabled" : "disabled", | |
540 | audit_initialized ? "" : " (after initialization)"); | |
541 | if (audit_initialized) | |
542 | audit_enabled = audit_default; | |
543 | return 0; | |
544 | } | |
545 | ||
546 | __setup("audit=", audit_enable); | |
547 | ||
16e1904e CW |
548 | static void audit_buffer_free(struct audit_buffer *ab) |
549 | { | |
550 | unsigned long flags; | |
551 | ||
8fc6115c CW |
552 | if (!ab) |
553 | return; | |
554 | ||
5ac52f33 CW |
555 | if (ab->skb) |
556 | kfree_skb(ab->skb); | |
b7d11258 | 557 | |
16e1904e CW |
558 | spin_lock_irqsave(&audit_freelist_lock, flags); |
559 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
560 | kfree(ab); | |
561 | else | |
562 | list_add(&ab->list, &audit_freelist); | |
563 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
564 | } | |
565 | ||
c0404993 SG |
566 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
567 | int gfp_mask, int type) | |
16e1904e CW |
568 | { |
569 | unsigned long flags; | |
570 | struct audit_buffer *ab = NULL; | |
c0404993 | 571 | struct nlmsghdr *nlh; |
16e1904e CW |
572 | |
573 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
574 | if (!list_empty(&audit_freelist)) { | |
575 | ab = list_entry(audit_freelist.next, | |
576 | struct audit_buffer, list); | |
577 | list_del(&ab->list); | |
578 | --audit_freelist_count; | |
579 | } | |
580 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
581 | ||
582 | if (!ab) { | |
4332bdd3 | 583 | ab = kmalloc(sizeof(*ab), gfp_mask); |
16e1904e | 584 | if (!ab) |
8fc6115c | 585 | goto err; |
16e1904e | 586 | } |
8fc6115c | 587 | |
4332bdd3 | 588 | ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); |
5ac52f33 | 589 | if (!ab->skb) |
8fc6115c CW |
590 | goto err; |
591 | ||
b7d11258 | 592 | ab->ctx = ctx; |
c0404993 SG |
593 | nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); |
594 | nlh->nlmsg_type = type; | |
595 | nlh->nlmsg_flags = 0; | |
596 | nlh->nlmsg_pid = 0; | |
597 | nlh->nlmsg_seq = 0; | |
16e1904e | 598 | return ab; |
8fc6115c CW |
599 | err: |
600 | audit_buffer_free(ab); | |
601 | return NULL; | |
16e1904e | 602 | } |
1da177e4 | 603 | |
bfb4496e DW |
604 | /* Compute a serial number for the audit record. Audit records are |
605 | * written to user-space as soon as they are generated, so a complete | |
606 | * audit record may be written in several pieces. The timestamp of the | |
607 | * record and this serial number are used by the user-space tools to | |
608 | * determine which pieces belong to the same audit record. The | |
609 | * (timestamp,serial) tuple is unique for each syscall and is live from | |
610 | * syscall entry to syscall exit. | |
611 | * | |
612 | * Atomic values are only guaranteed to be 24-bit, so we count down. | |
613 | * | |
614 | * NOTE: Another possibility is to store the formatted records off the | |
615 | * audit context (for those records that have a context), and emit them | |
616 | * all at syscall exit. However, this could delay the reporting of | |
617 | * significant errors until syscall exit (or never, if the system | |
618 | * halts). */ | |
619 | unsigned int audit_serial(void) | |
620 | { | |
621 | static atomic_t serial = ATOMIC_INIT(0xffffff); | |
622 | unsigned int a, b; | |
623 | ||
624 | do { | |
625 | a = atomic_read(&serial); | |
626 | if (atomic_dec_and_test(&serial)) | |
627 | atomic_set(&serial, 0xffffff); | |
628 | b = atomic_read(&serial); | |
629 | } while (b != a - 1); | |
630 | ||
631 | return 0xffffff - b; | |
632 | } | |
633 | ||
634 | static inline void audit_get_stamp(struct audit_context *ctx, | |
635 | struct timespec *t, unsigned int *serial) | |
636 | { | |
637 | if (ctx) | |
638 | auditsc_get_stamp(ctx, t, serial); | |
639 | else { | |
640 | *t = CURRENT_TIME; | |
641 | *serial = audit_serial(); | |
642 | } | |
643 | } | |
644 | ||
1da177e4 LT |
645 | /* Obtain an audit buffer. This routine does locking to obtain the |
646 | * audit buffer, but then no locking is required for calls to | |
647 | * audit_log_*format. If the tsk is a task that is currently in a | |
648 | * syscall, then the syscall is marked as auditable and an audit record | |
649 | * will be written at syscall exit. If there is no associated task, tsk | |
650 | * should be NULL. */ | |
c0404993 | 651 | struct audit_buffer *audit_log_start(struct audit_context *ctx, int type) |
1da177e4 LT |
652 | { |
653 | struct audit_buffer *ab = NULL; | |
1da177e4 | 654 | struct timespec t; |
d812ddbb | 655 | unsigned int serial; |
1da177e4 LT |
656 | |
657 | if (!audit_initialized) | |
658 | return NULL; | |
659 | ||
fb19b4c6 DW |
660 | if (audit_backlog_limit |
661 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit) { | |
662 | if (audit_rate_check()) | |
663 | printk(KERN_WARNING | |
664 | "audit: audit_backlog=%d > " | |
665 | "audit_backlog_limit=%d\n", | |
666 | skb_queue_len(&audit_skb_queue), | |
667 | audit_backlog_limit); | |
668 | audit_log_lost("backlog limit exceeded"); | |
669 | return NULL; | |
670 | } | |
671 | ||
c0404993 | 672 | ab = audit_buffer_alloc(ctx, GFP_ATOMIC, type); |
1da177e4 LT |
673 | if (!ab) { |
674 | audit_log_lost("out of memory in audit_log_start"); | |
675 | return NULL; | |
676 | } | |
677 | ||
bfb4496e | 678 | audit_get_stamp(ab->ctx, &t, &serial); |
197c69c6 | 679 | |
1da177e4 LT |
680 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
681 | t.tv_sec, t.tv_nsec/1000000, serial); | |
682 | return ab; | |
683 | } | |
684 | ||
8fc6115c | 685 | /** |
5ac52f33 | 686 | * audit_expand - expand skb in the audit buffer |
8fc6115c CW |
687 | * @ab: audit_buffer |
688 | * | |
689 | * Returns 0 (no space) on failed expansion, or available space if | |
690 | * successful. | |
691 | */ | |
e3b926b4 | 692 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
8fc6115c | 693 | { |
5ac52f33 | 694 | struct sk_buff *skb = ab->skb; |
e3b926b4 | 695 | int ret = pskb_expand_head(skb, skb_headroom(skb), extra, |
5ac52f33 CW |
696 | GFP_ATOMIC); |
697 | if (ret < 0) { | |
698 | audit_log_lost("out of memory in audit_expand"); | |
8fc6115c | 699 | return 0; |
5ac52f33 CW |
700 | } |
701 | return skb_tailroom(skb); | |
8fc6115c | 702 | } |
1da177e4 LT |
703 | |
704 | /* Format an audit message into the audit buffer. If there isn't enough | |
705 | * room in the audit buffer, more room will be allocated and vsnprint | |
706 | * will be called a second time. Currently, we assume that a printk | |
707 | * can't format message larger than 1024 bytes, so we don't either. */ | |
708 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
709 | va_list args) | |
710 | { | |
711 | int len, avail; | |
5ac52f33 | 712 | struct sk_buff *skb; |
eecb0a73 | 713 | va_list args2; |
1da177e4 LT |
714 | |
715 | if (!ab) | |
716 | return; | |
717 | ||
5ac52f33 CW |
718 | BUG_ON(!ab->skb); |
719 | skb = ab->skb; | |
720 | avail = skb_tailroom(skb); | |
721 | if (avail == 0) { | |
e3b926b4 | 722 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
8fc6115c CW |
723 | if (!avail) |
724 | goto out; | |
1da177e4 | 725 | } |
eecb0a73 | 726 | va_copy(args2, args); |
5ac52f33 | 727 | len = vsnprintf(skb->tail, avail, fmt, args); |
1da177e4 LT |
728 | if (len >= avail) { |
729 | /* The printk buffer is 1024 bytes long, so if we get | |
730 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
731 | * log everything that printk could have logged. */ | |
5e014b10 | 732 | avail = audit_expand(ab, max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); |
8fc6115c CW |
733 | if (!avail) |
734 | goto out; | |
eecb0a73 | 735 | len = vsnprintf(skb->tail, avail, fmt, args2); |
1da177e4 | 736 | } |
168b7173 SG |
737 | if (len > 0) |
738 | skb_put(skb, len); | |
8fc6115c CW |
739 | out: |
740 | return; | |
1da177e4 LT |
741 | } |
742 | ||
743 | /* Format a message into the audit buffer. All the work is done in | |
744 | * audit_log_vformat. */ | |
745 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
746 | { | |
747 | va_list args; | |
748 | ||
749 | if (!ab) | |
750 | return; | |
751 | va_start(args, fmt); | |
752 | audit_log_vformat(ab, fmt, args); | |
753 | va_end(args); | |
754 | } | |
755 | ||
168b7173 SG |
756 | /* This function will take the passed buf and convert it into a string of |
757 | * ascii hex digits. The new string is placed onto the skb. */ | |
758 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, | |
759 | size_t len) | |
83c7d091 | 760 | { |
168b7173 SG |
761 | int i, avail, new_len; |
762 | unsigned char *ptr; | |
763 | struct sk_buff *skb; | |
764 | static const unsigned char *hex = "0123456789ABCDEF"; | |
765 | ||
766 | BUG_ON(!ab->skb); | |
767 | skb = ab->skb; | |
768 | avail = skb_tailroom(skb); | |
769 | new_len = len<<1; | |
770 | if (new_len >= avail) { | |
771 | /* Round the buffer request up to the next multiple */ | |
772 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); | |
773 | avail = audit_expand(ab, new_len); | |
774 | if (!avail) | |
775 | return; | |
776 | } | |
83c7d091 | 777 | |
168b7173 SG |
778 | ptr = skb->tail; |
779 | for (i=0; i<len; i++) { | |
780 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ | |
781 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ | |
782 | } | |
783 | *ptr = 0; | |
784 | skb_put(skb, len << 1); /* new string is twice the old string */ | |
83c7d091 DW |
785 | } |
786 | ||
168b7173 SG |
787 | /* This code will escape a string that is passed to it if the string |
788 | * contains a control character, unprintable character, double quote mark, | |
789 | * or a space. Unescaped strings will start and end with a double quote mark. | |
790 | * Strings that are escaped are printed in hex (2 digits per char). */ | |
83c7d091 DW |
791 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) |
792 | { | |
81b7854d | 793 | const unsigned char *p = string; |
83c7d091 DW |
794 | |
795 | while (*p) { | |
168b7173 | 796 | if (*p == '"' || *p < 0x21 || *p > 0x7f) { |
83c7d091 DW |
797 | audit_log_hex(ab, string, strlen(string)); |
798 | return; | |
799 | } | |
800 | p++; | |
801 | } | |
802 | audit_log_format(ab, "\"%s\"", string); | |
803 | } | |
804 | ||
168b7173 | 805 | /* This is a helper-function to print the escaped d_path */ |
1da177e4 LT |
806 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, |
807 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
808 | { | |
168b7173 | 809 | char *p, *path; |
1da177e4 | 810 | |
8fc6115c CW |
811 | if (prefix) |
812 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 813 | |
168b7173 SG |
814 | /* We will allow 11 spaces for ' (deleted)' to be appended */ |
815 | path = kmalloc(PATH_MAX+11, GFP_KERNEL); | |
816 | if (!path) { | |
817 | audit_log_format(ab, "<no memory>"); | |
818 | return; | |
1da177e4 | 819 | } |
168b7173 SG |
820 | p = d_path(dentry, vfsmnt, path, PATH_MAX+11); |
821 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ | |
822 | /* FIXME: can we save some information here? */ | |
823 | audit_log_format(ab, "<too long>"); | |
824 | } else | |
825 | audit_log_untrustedstring(ab, p); | |
826 | kfree(path); | |
1da177e4 LT |
827 | } |
828 | ||
1da177e4 LT |
829 | /* The netlink_* functions cannot be called inside an irq context, so |
830 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
831 | * remove them from the queue outside the irq context. May be called in | |
832 | * any context. */ | |
b7d11258 | 833 | void audit_log_end(struct audit_buffer *ab) |
1da177e4 | 834 | { |
1da177e4 LT |
835 | if (!ab) |
836 | return; | |
837 | if (!audit_rate_check()) { | |
838 | audit_log_lost("rate limit exceeded"); | |
839 | } else { | |
b7d11258 DW |
840 | if (audit_pid) { |
841 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
842 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); | |
843 | skb_queue_tail(&audit_skb_queue, ab->skb); | |
844 | ab->skb = NULL; | |
845 | wake_up_interruptible(&kauditd_wait); | |
846 | } else { | |
847 | printk("%s\n", ab->skb->data + NLMSG_SPACE(0)); | |
848 | } | |
1da177e4 | 849 | } |
16e1904e | 850 | audit_buffer_free(ab); |
1da177e4 LT |
851 | } |
852 | ||
1da177e4 LT |
853 | /* Log an audit record. This is a convenience function that calls |
854 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
855 | * called in any context. */ | |
c0404993 | 856 | void audit_log(struct audit_context *ctx, int type, const char *fmt, ...) |
1da177e4 LT |
857 | { |
858 | struct audit_buffer *ab; | |
859 | va_list args; | |
860 | ||
c0404993 | 861 | ab = audit_log_start(ctx, type); |
1da177e4 LT |
862 | if (ab) { |
863 | va_start(args, fmt); | |
864 | audit_log_vformat(ab, fmt, args); | |
865 | va_end(args); | |
866 | audit_log_end(ab); | |
867 | } | |
868 | } |