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 LT |
110 | /* There are three lists of rules -- one to search at task creation |
111 | * time, one to search at syscall entry time, and another to search at | |
112 | * syscall exit time. */ | |
113 | static LIST_HEAD(audit_tsklist); | |
114 | static LIST_HEAD(audit_entlist); | |
115 | static LIST_HEAD(audit_extlist); | |
116 | ||
117 | /* The netlink socket is only to be read by 1 CPU, which lets us assume | |
23f32d18 | 118 | * that list additions and deletions never happen simultaneously in |
1da177e4 LT |
119 | * auditsc.c */ |
120 | static DECLARE_MUTEX(audit_netlink_sem); | |
121 | ||
122 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
123 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
124 | * should be at least that large. */ | |
125 | #define AUDIT_BUFSIZ 1024 | |
126 | ||
127 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
128 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
129 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
130 | ||
131 | /* The audit_buffer is used when formatting an audit record. The caller | |
132 | * locks briefly to get the record off the freelist or to allocate the | |
133 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
134 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
135 | * use simultaneously. */ | |
136 | struct audit_buffer { | |
137 | struct list_head list; | |
8fc6115c | 138 | struct sk_buff *skb; /* formatted skb ready to send */ |
1da177e4 | 139 | struct audit_context *ctx; /* NULL or associated context */ |
1da177e4 LT |
140 | }; |
141 | ||
c0404993 SG |
142 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
143 | { | |
144 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
145 | nlh->nlmsg_pid = pid; | |
146 | } | |
147 | ||
1da177e4 LT |
148 | struct audit_entry { |
149 | struct list_head list; | |
150 | struct audit_rule rule; | |
151 | }; | |
152 | ||
1da177e4 LT |
153 | static void audit_panic(const char *message) |
154 | { | |
155 | switch (audit_failure) | |
156 | { | |
157 | case AUDIT_FAIL_SILENT: | |
158 | break; | |
159 | case AUDIT_FAIL_PRINTK: | |
160 | printk(KERN_ERR "audit: %s\n", message); | |
161 | break; | |
162 | case AUDIT_FAIL_PANIC: | |
163 | panic("audit: %s\n", message); | |
164 | break; | |
165 | } | |
166 | } | |
167 | ||
168 | static inline int audit_rate_check(void) | |
169 | { | |
170 | static unsigned long last_check = 0; | |
171 | static int messages = 0; | |
172 | static DEFINE_SPINLOCK(lock); | |
173 | unsigned long flags; | |
174 | unsigned long now; | |
175 | unsigned long elapsed; | |
176 | int retval = 0; | |
177 | ||
178 | if (!audit_rate_limit) return 1; | |
179 | ||
180 | spin_lock_irqsave(&lock, flags); | |
181 | if (++messages < audit_rate_limit) { | |
182 | retval = 1; | |
183 | } else { | |
184 | now = jiffies; | |
185 | elapsed = now - last_check; | |
186 | if (elapsed > HZ) { | |
187 | last_check = now; | |
188 | messages = 0; | |
189 | retval = 1; | |
190 | } | |
191 | } | |
192 | spin_unlock_irqrestore(&lock, flags); | |
193 | ||
194 | return retval; | |
195 | } | |
196 | ||
197 | /* Emit at least 1 message per second, even if audit_rate_check is | |
198 | * throttling. */ | |
199 | void audit_log_lost(const char *message) | |
200 | { | |
201 | static unsigned long last_msg = 0; | |
202 | static DEFINE_SPINLOCK(lock); | |
203 | unsigned long flags; | |
204 | unsigned long now; | |
205 | int print; | |
206 | ||
207 | atomic_inc(&audit_lost); | |
208 | ||
209 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); | |
210 | ||
211 | if (!print) { | |
212 | spin_lock_irqsave(&lock, flags); | |
213 | now = jiffies; | |
214 | if (now - last_msg > HZ) { | |
215 | print = 1; | |
216 | last_msg = now; | |
217 | } | |
218 | spin_unlock_irqrestore(&lock, flags); | |
219 | } | |
220 | ||
221 | if (print) { | |
222 | printk(KERN_WARNING | |
b7d11258 | 223 | "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n", |
1da177e4 | 224 | atomic_read(&audit_lost), |
1da177e4 LT |
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; | |
c0404993 | 236 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 237 | "audit_rate_limit=%d old=%d by auid=%u", |
c94c257c | 238 | audit_rate_limit, old, loginuid); |
1da177e4 LT |
239 | return old; |
240 | } | |
241 | ||
c94c257c | 242 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
243 | { |
244 | int old = audit_backlog_limit; | |
245 | audit_backlog_limit = limit; | |
c0404993 | 246 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 247 | "audit_backlog_limit=%d old=%d by auid=%u", |
c94c257c | 248 | audit_backlog_limit, old, loginuid); |
1da177e4 LT |
249 | return old; |
250 | } | |
251 | ||
c94c257c | 252 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
253 | { |
254 | int old = audit_enabled; | |
255 | if (state != 0 && state != 1) | |
256 | return -EINVAL; | |
257 | audit_enabled = state; | |
c0404993 | 258 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 259 | "audit_enabled=%d old=%d by auid=%u", |
c0404993 | 260 | audit_enabled, old, loginuid); |
1da177e4 LT |
261 | return old; |
262 | } | |
263 | ||
c94c257c | 264 | static int audit_set_failure(int state, uid_t loginuid) |
1da177e4 LT |
265 | { |
266 | int old = audit_failure; | |
267 | if (state != AUDIT_FAIL_SILENT | |
268 | && state != AUDIT_FAIL_PRINTK | |
269 | && state != AUDIT_FAIL_PANIC) | |
270 | return -EINVAL; | |
271 | audit_failure = state; | |
c0404993 | 272 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 273 | "audit_failure=%d old=%d by auid=%u", |
c0404993 | 274 | audit_failure, old, loginuid); |
1da177e4 LT |
275 | return old; |
276 | } | |
277 | ||
b7d11258 DW |
278 | int kauditd_thread(void *dummy) |
279 | { | |
280 | struct sk_buff *skb; | |
281 | ||
282 | while (1) { | |
283 | skb = skb_dequeue(&audit_skb_queue); | |
284 | if (skb) { | |
285 | if (audit_pid) { | |
286 | int err = netlink_unicast(audit_sock, skb, audit_pid, 0); | |
287 | if (err < 0) { | |
288 | BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */ | |
289 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); | |
290 | audit_pid = 0; | |
291 | } | |
292 | } else { | |
293 | printk(KERN_ERR "%s\n", skb->data + NLMSG_SPACE(0)); | |
294 | kfree_skb(skb); | |
295 | } | |
296 | } else { | |
297 | DECLARE_WAITQUEUE(wait, current); | |
298 | set_current_state(TASK_INTERRUPTIBLE); | |
299 | add_wait_queue(&kauditd_wait, &wait); | |
300 | ||
301 | if (!skb_queue_len(&audit_skb_queue)) | |
302 | schedule(); | |
303 | ||
304 | __set_current_state(TASK_RUNNING); | |
305 | remove_wait_queue(&kauditd_wait, &wait); | |
306 | } | |
307 | } | |
308 | } | |
309 | ||
1da177e4 LT |
310 | void audit_send_reply(int pid, int seq, int type, int done, int multi, |
311 | void *payload, int size) | |
312 | { | |
313 | struct sk_buff *skb; | |
314 | struct nlmsghdr *nlh; | |
315 | int len = NLMSG_SPACE(size); | |
316 | void *data; | |
317 | int flags = multi ? NLM_F_MULTI : 0; | |
318 | int t = done ? NLMSG_DONE : type; | |
319 | ||
320 | skb = alloc_skb(len, GFP_KERNEL); | |
321 | if (!skb) | |
b7d11258 | 322 | return; |
1da177e4 | 323 | |
b7d11258 | 324 | nlh = NLMSG_PUT(skb, pid, seq, t, size); |
1da177e4 LT |
325 | nlh->nlmsg_flags = flags; |
326 | data = NLMSG_DATA(nlh); | |
327 | memcpy(data, payload, size); | |
b7d11258 DW |
328 | |
329 | /* Ignore failure. It'll only happen if the sender goes away, | |
330 | because our timeout is set to infinite. */ | |
331 | netlink_unicast(audit_sock, skb, pid, 0); | |
1da177e4 LT |
332 | return; |
333 | ||
334 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
335 | if (skb) | |
336 | kfree_skb(skb); | |
337 | } | |
338 | ||
339 | /* | |
340 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
341 | * control messages. | |
342 | */ | |
343 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
344 | { | |
345 | int err = 0; | |
346 | ||
347 | switch (msg_type) { | |
348 | case AUDIT_GET: | |
349 | case AUDIT_LIST: | |
350 | case AUDIT_SET: | |
351 | case AUDIT_ADD: | |
352 | case AUDIT_DEL: | |
c2f0c7c3 | 353 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
354 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
355 | err = -EPERM; | |
356 | break; | |
05474106 | 357 | case AUDIT_USER: |
209aba03 | 358 | case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG: |
1da177e4 LT |
359 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) |
360 | err = -EPERM; | |
361 | break; | |
362 | default: /* bad msg */ | |
363 | err = -EINVAL; | |
364 | } | |
365 | ||
366 | return err; | |
367 | } | |
368 | ||
369 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
370 | { | |
371 | u32 uid, pid, seq; | |
372 | void *data; | |
373 | struct audit_status *status_get, status_set; | |
374 | int err; | |
c0404993 | 375 | struct audit_buffer *ab; |
1da177e4 | 376 | u16 msg_type = nlh->nlmsg_type; |
c94c257c | 377 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 378 | struct audit_sig_info sig_data; |
1da177e4 LT |
379 | |
380 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
381 | if (err) | |
382 | return err; | |
383 | ||
b7d11258 DW |
384 | /* As soon as there's any sign of userspace auditd, start kauditd to talk to it */ |
385 | if (!kauditd_task) | |
386 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); | |
387 | if (IS_ERR(kauditd_task)) { | |
388 | err = PTR_ERR(kauditd_task); | |
389 | kauditd_task = NULL; | |
390 | return err; | |
391 | } | |
392 | ||
1da177e4 LT |
393 | pid = NETLINK_CREDS(skb)->pid; |
394 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 395 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
396 | seq = nlh->nlmsg_seq; |
397 | data = NLMSG_DATA(nlh); | |
398 | ||
399 | switch (msg_type) { | |
400 | case AUDIT_GET: | |
401 | status_set.enabled = audit_enabled; | |
402 | status_set.failure = audit_failure; | |
403 | status_set.pid = audit_pid; | |
404 | status_set.rate_limit = audit_rate_limit; | |
405 | status_set.backlog_limit = audit_backlog_limit; | |
406 | status_set.lost = atomic_read(&audit_lost); | |
b7d11258 | 407 | status_set.backlog = skb_queue_len(&audit_skb_queue); |
1da177e4 LT |
408 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, |
409 | &status_set, sizeof(status_set)); | |
410 | break; | |
411 | case AUDIT_SET: | |
412 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
413 | return -EINVAL; | |
414 | status_get = (struct audit_status *)data; | |
415 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 416 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
417 | if (err < 0) return err; |
418 | } | |
419 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 420 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
421 | if (err < 0) return err; |
422 | } | |
423 | if (status_get->mask & AUDIT_STATUS_PID) { | |
424 | int old = audit_pid; | |
425 | audit_pid = status_get->pid; | |
c0404993 | 426 | audit_log(NULL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 427 | "audit_pid=%d old=%d by auid=%u", |
c94c257c | 428 | audit_pid, old, loginuid); |
1da177e4 LT |
429 | } |
430 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 431 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 432 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
433 | audit_set_backlog_limit(status_get->backlog_limit, |
434 | loginuid); | |
1da177e4 | 435 | break; |
05474106 | 436 | case AUDIT_USER: |
209aba03 | 437 | case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG: |
c0404993 SG |
438 | ab = audit_log_start(NULL, msg_type); |
439 | if (!ab) | |
440 | break; /* audit_panic has been called */ | |
441 | audit_log_format(ab, | |
326e9c8b | 442 | "user pid=%d uid=%u auid=%u" |
c94c257c | 443 | " msg='%.1024s'", |
326e9c8b | 444 | pid, uid, loginuid, (char *)data); |
c0404993 SG |
445 | audit_set_pid(ab, pid); |
446 | audit_log_end(ab); | |
1da177e4 LT |
447 | break; |
448 | case AUDIT_ADD: | |
449 | case AUDIT_DEL: | |
450 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
451 | return -EINVAL; | |
452 | /* fallthrough */ | |
453 | case AUDIT_LIST: | |
1da177e4 | 454 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, |
c94c257c | 455 | uid, seq, data, loginuid); |
1da177e4 | 456 | break; |
c2f0c7c3 SG |
457 | case AUDIT_SIGNAL_INFO: |
458 | sig_data.uid = audit_sig_uid; | |
459 | sig_data.pid = audit_sig_pid; | |
460 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
461 | 0, 0, &sig_data, sizeof(sig_data)); | |
462 | break; | |
1da177e4 LT |
463 | default: |
464 | err = -EINVAL; | |
465 | break; | |
466 | } | |
467 | ||
468 | return err < 0 ? err : 0; | |
469 | } | |
470 | ||
471 | /* Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
472 | * processed by audit_receive_msg. Malformed skbs with wrong length are | |
473 | * discarded silently. */ | |
2a0a6ebe | 474 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
475 | { |
476 | int err; | |
477 | struct nlmsghdr *nlh; | |
478 | u32 rlen; | |
479 | ||
480 | while (skb->len >= NLMSG_SPACE(0)) { | |
481 | nlh = (struct nlmsghdr *)skb->data; | |
482 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 483 | return; |
1da177e4 LT |
484 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
485 | if (rlen > skb->len) | |
486 | rlen = skb->len; | |
487 | if ((err = audit_receive_msg(skb, nlh))) { | |
488 | netlink_ack(skb, nlh, err); | |
489 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
490 | netlink_ack(skb, nlh, 0); | |
491 | skb_pull(skb, rlen); | |
492 | } | |
1da177e4 LT |
493 | } |
494 | ||
495 | /* Receive messages from netlink socket. */ | |
496 | static void audit_receive(struct sock *sk, int length) | |
497 | { | |
498 | struct sk_buff *skb; | |
2a0a6ebe | 499 | unsigned int qlen; |
1da177e4 | 500 | |
2a0a6ebe | 501 | down(&audit_netlink_sem); |
1da177e4 | 502 | |
2a0a6ebe HX |
503 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
504 | skb = skb_dequeue(&sk->sk_receive_queue); | |
505 | audit_receive_skb(skb); | |
506 | kfree_skb(skb); | |
1da177e4 LT |
507 | } |
508 | up(&audit_netlink_sem); | |
509 | } | |
510 | ||
1da177e4 LT |
511 | |
512 | /* Initialize audit support at boot time. */ | |
513 | static int __init audit_init(void) | |
514 | { | |
515 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
516 | audit_default ? "enabled" : "disabled"); | |
4fdb3bb7 HW |
517 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive, |
518 | THIS_MODULE); | |
1da177e4 LT |
519 | if (!audit_sock) |
520 | audit_panic("cannot initialize netlink socket"); | |
521 | ||
b7d11258 DW |
522 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; |
523 | skb_queue_head_init(&audit_skb_queue); | |
1da177e4 LT |
524 | audit_initialized = 1; |
525 | audit_enabled = audit_default; | |
c0404993 | 526 | audit_log(NULL, AUDIT_KERNEL, "initialized"); |
1da177e4 LT |
527 | return 0; |
528 | } | |
1da177e4 LT |
529 | __initcall(audit_init); |
530 | ||
531 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
532 | static int __init audit_enable(char *str) | |
533 | { | |
534 | audit_default = !!simple_strtol(str, NULL, 0); | |
535 | printk(KERN_INFO "audit: %s%s\n", | |
536 | audit_default ? "enabled" : "disabled", | |
537 | audit_initialized ? "" : " (after initialization)"); | |
538 | if (audit_initialized) | |
539 | audit_enabled = audit_default; | |
540 | return 0; | |
541 | } | |
542 | ||
543 | __setup("audit=", audit_enable); | |
544 | ||
16e1904e CW |
545 | static void audit_buffer_free(struct audit_buffer *ab) |
546 | { | |
547 | unsigned long flags; | |
548 | ||
8fc6115c CW |
549 | if (!ab) |
550 | return; | |
551 | ||
5ac52f33 CW |
552 | if (ab->skb) |
553 | kfree_skb(ab->skb); | |
b7d11258 | 554 | |
16e1904e CW |
555 | spin_lock_irqsave(&audit_freelist_lock, flags); |
556 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
557 | kfree(ab); | |
558 | else | |
559 | list_add(&ab->list, &audit_freelist); | |
560 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
561 | } | |
562 | ||
c0404993 SG |
563 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
564 | int gfp_mask, int type) | |
16e1904e CW |
565 | { |
566 | unsigned long flags; | |
567 | struct audit_buffer *ab = NULL; | |
c0404993 | 568 | struct nlmsghdr *nlh; |
16e1904e CW |
569 | |
570 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
571 | if (!list_empty(&audit_freelist)) { | |
572 | ab = list_entry(audit_freelist.next, | |
573 | struct audit_buffer, list); | |
574 | list_del(&ab->list); | |
575 | --audit_freelist_count; | |
576 | } | |
577 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
578 | ||
579 | if (!ab) { | |
4332bdd3 | 580 | ab = kmalloc(sizeof(*ab), gfp_mask); |
16e1904e | 581 | if (!ab) |
8fc6115c | 582 | goto err; |
16e1904e | 583 | } |
8fc6115c | 584 | |
4332bdd3 | 585 | ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); |
5ac52f33 | 586 | if (!ab->skb) |
8fc6115c CW |
587 | goto err; |
588 | ||
b7d11258 | 589 | ab->ctx = ctx; |
c0404993 SG |
590 | nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); |
591 | nlh->nlmsg_type = type; | |
592 | nlh->nlmsg_flags = 0; | |
593 | nlh->nlmsg_pid = 0; | |
594 | nlh->nlmsg_seq = 0; | |
16e1904e | 595 | return ab; |
8fc6115c CW |
596 | err: |
597 | audit_buffer_free(ab); | |
598 | return NULL; | |
16e1904e | 599 | } |
1da177e4 | 600 | |
bfb4496e DW |
601 | /* Compute a serial number for the audit record. Audit records are |
602 | * written to user-space as soon as they are generated, so a complete | |
603 | * audit record may be written in several pieces. The timestamp of the | |
604 | * record and this serial number are used by the user-space tools to | |
605 | * determine which pieces belong to the same audit record. The | |
606 | * (timestamp,serial) tuple is unique for each syscall and is live from | |
607 | * syscall entry to syscall exit. | |
608 | * | |
609 | * Atomic values are only guaranteed to be 24-bit, so we count down. | |
610 | * | |
611 | * NOTE: Another possibility is to store the formatted records off the | |
612 | * audit context (for those records that have a context), and emit them | |
613 | * all at syscall exit. However, this could delay the reporting of | |
614 | * significant errors until syscall exit (or never, if the system | |
615 | * halts). */ | |
616 | unsigned int audit_serial(void) | |
617 | { | |
618 | static atomic_t serial = ATOMIC_INIT(0xffffff); | |
619 | unsigned int a, b; | |
620 | ||
621 | do { | |
622 | a = atomic_read(&serial); | |
623 | if (atomic_dec_and_test(&serial)) | |
624 | atomic_set(&serial, 0xffffff); | |
625 | b = atomic_read(&serial); | |
626 | } while (b != a - 1); | |
627 | ||
628 | return 0xffffff - b; | |
629 | } | |
630 | ||
631 | static inline void audit_get_stamp(struct audit_context *ctx, | |
632 | struct timespec *t, unsigned int *serial) | |
633 | { | |
634 | if (ctx) | |
635 | auditsc_get_stamp(ctx, t, serial); | |
636 | else { | |
637 | *t = CURRENT_TIME; | |
638 | *serial = audit_serial(); | |
639 | } | |
640 | } | |
641 | ||
1da177e4 LT |
642 | /* Obtain an audit buffer. This routine does locking to obtain the |
643 | * audit buffer, but then no locking is required for calls to | |
644 | * audit_log_*format. If the tsk is a task that is currently in a | |
645 | * syscall, then the syscall is marked as auditable and an audit record | |
646 | * will be written at syscall exit. If there is no associated task, tsk | |
647 | * should be NULL. */ | |
c0404993 | 648 | struct audit_buffer *audit_log_start(struct audit_context *ctx, int type) |
1da177e4 LT |
649 | { |
650 | struct audit_buffer *ab = NULL; | |
1da177e4 | 651 | struct timespec t; |
d812ddbb | 652 | unsigned int serial; |
1da177e4 LT |
653 | |
654 | if (!audit_initialized) | |
655 | return NULL; | |
656 | ||
fb19b4c6 DW |
657 | if (audit_backlog_limit |
658 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit) { | |
659 | if (audit_rate_check()) | |
660 | printk(KERN_WARNING | |
661 | "audit: audit_backlog=%d > " | |
662 | "audit_backlog_limit=%d\n", | |
663 | skb_queue_len(&audit_skb_queue), | |
664 | audit_backlog_limit); | |
665 | audit_log_lost("backlog limit exceeded"); | |
666 | return NULL; | |
667 | } | |
668 | ||
c0404993 | 669 | ab = audit_buffer_alloc(ctx, GFP_ATOMIC, type); |
1da177e4 LT |
670 | if (!ab) { |
671 | audit_log_lost("out of memory in audit_log_start"); | |
672 | return NULL; | |
673 | } | |
674 | ||
bfb4496e | 675 | audit_get_stamp(ab->ctx, &t, &serial); |
197c69c6 | 676 | |
1da177e4 LT |
677 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
678 | t.tv_sec, t.tv_nsec/1000000, serial); | |
679 | return ab; | |
680 | } | |
681 | ||
8fc6115c | 682 | /** |
5ac52f33 | 683 | * audit_expand - expand skb in the audit buffer |
8fc6115c CW |
684 | * @ab: audit_buffer |
685 | * | |
686 | * Returns 0 (no space) on failed expansion, or available space if | |
687 | * successful. | |
688 | */ | |
e3b926b4 | 689 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
8fc6115c | 690 | { |
5ac52f33 | 691 | struct sk_buff *skb = ab->skb; |
e3b926b4 | 692 | int ret = pskb_expand_head(skb, skb_headroom(skb), extra, |
5ac52f33 CW |
693 | GFP_ATOMIC); |
694 | if (ret < 0) { | |
695 | audit_log_lost("out of memory in audit_expand"); | |
8fc6115c | 696 | return 0; |
5ac52f33 CW |
697 | } |
698 | return skb_tailroom(skb); | |
8fc6115c | 699 | } |
1da177e4 LT |
700 | |
701 | /* Format an audit message into the audit buffer. If there isn't enough | |
702 | * room in the audit buffer, more room will be allocated and vsnprint | |
703 | * will be called a second time. Currently, we assume that a printk | |
704 | * can't format message larger than 1024 bytes, so we don't either. */ | |
705 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, | |
706 | va_list args) | |
707 | { | |
708 | int len, avail; | |
5ac52f33 | 709 | struct sk_buff *skb; |
eecb0a73 | 710 | va_list args2; |
1da177e4 LT |
711 | |
712 | if (!ab) | |
713 | return; | |
714 | ||
5ac52f33 CW |
715 | BUG_ON(!ab->skb); |
716 | skb = ab->skb; | |
717 | avail = skb_tailroom(skb); | |
718 | if (avail == 0) { | |
e3b926b4 | 719 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
8fc6115c CW |
720 | if (!avail) |
721 | goto out; | |
1da177e4 | 722 | } |
eecb0a73 | 723 | va_copy(args2, args); |
5ac52f33 | 724 | len = vsnprintf(skb->tail, avail, fmt, args); |
1da177e4 LT |
725 | if (len >= avail) { |
726 | /* The printk buffer is 1024 bytes long, so if we get | |
727 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
728 | * log everything that printk could have logged. */ | |
5e014b10 | 729 | avail = audit_expand(ab, max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); |
8fc6115c CW |
730 | if (!avail) |
731 | goto out; | |
eecb0a73 | 732 | len = vsnprintf(skb->tail, avail, fmt, args2); |
1da177e4 | 733 | } |
168b7173 SG |
734 | if (len > 0) |
735 | skb_put(skb, len); | |
8fc6115c CW |
736 | out: |
737 | return; | |
1da177e4 LT |
738 | } |
739 | ||
740 | /* Format a message into the audit buffer. All the work is done in | |
741 | * audit_log_vformat. */ | |
742 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) | |
743 | { | |
744 | va_list args; | |
745 | ||
746 | if (!ab) | |
747 | return; | |
748 | va_start(args, fmt); | |
749 | audit_log_vformat(ab, fmt, args); | |
750 | va_end(args); | |
751 | } | |
752 | ||
168b7173 SG |
753 | /* This function will take the passed buf and convert it into a string of |
754 | * ascii hex digits. The new string is placed onto the skb. */ | |
755 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, | |
756 | size_t len) | |
83c7d091 | 757 | { |
168b7173 SG |
758 | int i, avail, new_len; |
759 | unsigned char *ptr; | |
760 | struct sk_buff *skb; | |
761 | static const unsigned char *hex = "0123456789ABCDEF"; | |
762 | ||
763 | BUG_ON(!ab->skb); | |
764 | skb = ab->skb; | |
765 | avail = skb_tailroom(skb); | |
766 | new_len = len<<1; | |
767 | if (new_len >= avail) { | |
768 | /* Round the buffer request up to the next multiple */ | |
769 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); | |
770 | avail = audit_expand(ab, new_len); | |
771 | if (!avail) | |
772 | return; | |
773 | } | |
83c7d091 | 774 | |
168b7173 SG |
775 | ptr = skb->tail; |
776 | for (i=0; i<len; i++) { | |
777 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ | |
778 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ | |
779 | } | |
780 | *ptr = 0; | |
781 | skb_put(skb, len << 1); /* new string is twice the old string */ | |
83c7d091 | 782 | } |
783 | ||
168b7173 SG |
784 | /* This code will escape a string that is passed to it if the string |
785 | * contains a control character, unprintable character, double quote mark, | |
786 | * or a space. Unescaped strings will start and end with a double quote mark. | |
787 | * Strings that are escaped are printed in hex (2 digits per char). */ | |
83c7d091 | 788 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) |
789 | { | |
81b7854d | 790 | const unsigned char *p = string; |
83c7d091 | 791 | |
792 | while (*p) { | |
168b7173 | 793 | if (*p == '"' || *p < 0x21 || *p > 0x7f) { |
83c7d091 | 794 | audit_log_hex(ab, string, strlen(string)); |
795 | return; | |
796 | } | |
797 | p++; | |
798 | } | |
799 | audit_log_format(ab, "\"%s\"", string); | |
800 | } | |
801 | ||
168b7173 | 802 | /* This is a helper-function to print the escaped d_path */ |
1da177e4 LT |
803 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, |
804 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
805 | { | |
168b7173 | 806 | char *p, *path; |
1da177e4 | 807 | |
8fc6115c CW |
808 | if (prefix) |
809 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 810 | |
168b7173 SG |
811 | /* We will allow 11 spaces for ' (deleted)' to be appended */ |
812 | path = kmalloc(PATH_MAX+11, GFP_KERNEL); | |
813 | if (!path) { | |
814 | audit_log_format(ab, "<no memory>"); | |
815 | return; | |
1da177e4 | 816 | } |
168b7173 SG |
817 | p = d_path(dentry, vfsmnt, path, PATH_MAX+11); |
818 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ | |
819 | /* FIXME: can we save some information here? */ | |
820 | audit_log_format(ab, "<too long>"); | |
821 | } else | |
822 | audit_log_untrustedstring(ab, p); | |
823 | kfree(path); | |
1da177e4 LT |
824 | } |
825 | ||
1da177e4 LT |
826 | /* The netlink_* functions cannot be called inside an irq context, so |
827 | * the audit buffer is places on a queue and a tasklet is scheduled to | |
828 | * remove them from the queue outside the irq context. May be called in | |
829 | * any context. */ | |
b7d11258 | 830 | void audit_log_end(struct audit_buffer *ab) |
1da177e4 | 831 | { |
1da177e4 LT |
832 | if (!ab) |
833 | return; | |
834 | if (!audit_rate_check()) { | |
835 | audit_log_lost("rate limit exceeded"); | |
836 | } else { | |
b7d11258 DW |
837 | if (audit_pid) { |
838 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
839 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); | |
840 | skb_queue_tail(&audit_skb_queue, ab->skb); | |
841 | ab->skb = NULL; | |
842 | wake_up_interruptible(&kauditd_wait); | |
843 | } else { | |
844 | printk("%s\n", ab->skb->data + NLMSG_SPACE(0)); | |
845 | } | |
1da177e4 | 846 | } |
16e1904e | 847 | audit_buffer_free(ab); |
1da177e4 LT |
848 | } |
849 | ||
1da177e4 LT |
850 | /* Log an audit record. This is a convenience function that calls |
851 | * audit_log_start, audit_log_vformat, and audit_log_end. It may be | |
852 | * called in any context. */ | |
c0404993 | 853 | void audit_log(struct audit_context *ctx, int type, const char *fmt, ...) |
1da177e4 LT |
854 | { |
855 | struct audit_buffer *ab; | |
856 | va_list args; | |
857 | ||
c0404993 | 858 | ab = audit_log_start(ctx, type); |
1da177e4 LT |
859 | if (ab) { |
860 | va_start(args, fmt); | |
861 | audit_log_vformat(ab, fmt, args); | |
862 | va_end(args); | |
863 | audit_log_end(ab); | |
864 | } | |
865 | } |