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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> | |
1da177e4 | 45 | #include <asm/types.h> |
715b49ef | 46 | #include <asm/atomic.h> |
1da177e4 LT |
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 | 74 | |
b0dd25a8 | 75 | /* If audit_rate_limit is non-zero, limit the rate of sending audit records |
1da177e4 LT |
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; | |
ac4cec44 DW |
82 | static int audit_backlog_wait_time = 60 * HZ; |
83 | static int audit_backlog_wait_overflow = 0; | |
1da177e4 | 84 | |
c2f0c7c3 SG |
85 | /* The identity of the user shutting down the audit system. */ |
86 | uid_t audit_sig_uid = -1; | |
87 | pid_t audit_sig_pid = -1; | |
88 | ||
1da177e4 LT |
89 | /* Records can be lost in several ways: |
90 | 0) [suppressed in audit_alloc] | |
91 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] | |
92 | 2) out of memory in audit_log_move [alloc_skb] | |
93 | 3) suppressed due to audit_rate_limit | |
94 | 4) suppressed due to audit_backlog_limit | |
95 | */ | |
96 | static atomic_t audit_lost = ATOMIC_INIT(0); | |
97 | ||
98 | /* The netlink socket. */ | |
99 | static struct sock *audit_sock; | |
100 | ||
b7d11258 | 101 | /* The audit_freelist is a list of pre-allocated audit buffers (if more |
1da177e4 LT |
102 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of |
103 | * being placed on the freelist). */ | |
1da177e4 | 104 | static DEFINE_SPINLOCK(audit_freelist_lock); |
b0dd25a8 | 105 | static int audit_freelist_count; |
1da177e4 LT |
106 | static LIST_HEAD(audit_freelist); |
107 | ||
b7d11258 DW |
108 | static struct sk_buff_head audit_skb_queue; |
109 | static struct task_struct *kauditd_task; | |
110 | static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); | |
9ad9ad38 | 111 | static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); |
1da177e4 LT |
112 | |
113 | /* The netlink socket is only to be read by 1 CPU, which lets us assume | |
23f32d18 | 114 | * that list additions and deletions never happen simultaneously in |
1da177e4 | 115 | * auditsc.c */ |
f6a789d1 | 116 | DECLARE_MUTEX(audit_netlink_sem); |
1da177e4 LT |
117 | |
118 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting | |
119 | * audit records. Since printk uses a 1024 byte buffer, this buffer | |
120 | * should be at least that large. */ | |
121 | #define AUDIT_BUFSIZ 1024 | |
122 | ||
123 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the | |
124 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ | |
125 | #define AUDIT_MAXFREE (2*NR_CPUS) | |
126 | ||
127 | /* The audit_buffer is used when formatting an audit record. The caller | |
128 | * locks briefly to get the record off the freelist or to allocate the | |
129 | * buffer, and locks briefly to send the buffer to the netlink layer or | |
130 | * to place it on a transmit queue. Multiple audit_buffers can be in | |
131 | * use simultaneously. */ | |
132 | struct audit_buffer { | |
133 | struct list_head list; | |
8fc6115c | 134 | struct sk_buff *skb; /* formatted skb ready to send */ |
1da177e4 | 135 | struct audit_context *ctx; /* NULL or associated context */ |
9796fdd8 | 136 | gfp_t gfp_mask; |
1da177e4 LT |
137 | }; |
138 | ||
c0404993 SG |
139 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
140 | { | |
141 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
142 | nlh->nlmsg_pid = pid; | |
143 | } | |
144 | ||
8c8570fb | 145 | void audit_panic(const char *message) |
1da177e4 LT |
146 | { |
147 | switch (audit_failure) | |
148 | { | |
149 | case AUDIT_FAIL_SILENT: | |
150 | break; | |
151 | case AUDIT_FAIL_PRINTK: | |
152 | printk(KERN_ERR "audit: %s\n", message); | |
153 | break; | |
154 | case AUDIT_FAIL_PANIC: | |
155 | panic("audit: %s\n", message); | |
156 | break; | |
157 | } | |
158 | } | |
159 | ||
160 | static inline int audit_rate_check(void) | |
161 | { | |
162 | static unsigned long last_check = 0; | |
163 | static int messages = 0; | |
164 | static DEFINE_SPINLOCK(lock); | |
165 | unsigned long flags; | |
166 | unsigned long now; | |
167 | unsigned long elapsed; | |
168 | int retval = 0; | |
169 | ||
170 | if (!audit_rate_limit) return 1; | |
171 | ||
172 | spin_lock_irqsave(&lock, flags); | |
173 | if (++messages < audit_rate_limit) { | |
174 | retval = 1; | |
175 | } else { | |
176 | now = jiffies; | |
177 | elapsed = now - last_check; | |
178 | if (elapsed > HZ) { | |
179 | last_check = now; | |
180 | messages = 0; | |
181 | retval = 1; | |
182 | } | |
183 | } | |
184 | spin_unlock_irqrestore(&lock, flags); | |
185 | ||
186 | return retval; | |
187 | } | |
188 | ||
b0dd25a8 RD |
189 | /** |
190 | * audit_log_lost - conditionally log lost audit message event | |
191 | * @message: the message stating reason for lost audit message | |
192 | * | |
193 | * Emit at least 1 message per second, even if audit_rate_check is | |
194 | * throttling. | |
195 | * Always increment the lost messages counter. | |
196 | */ | |
1da177e4 LT |
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 | |
b7d11258 | 221 | "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n", |
1da177e4 | 222 | atomic_read(&audit_lost), |
1da177e4 LT |
223 | audit_rate_limit, |
224 | audit_backlog_limit); | |
225 | audit_panic(message); | |
226 | } | |
1da177e4 LT |
227 | } |
228 | ||
c94c257c | 229 | static int audit_set_rate_limit(int limit, uid_t loginuid) |
1da177e4 LT |
230 | { |
231 | int old = audit_rate_limit; | |
232 | audit_rate_limit = limit; | |
9ad9ad38 | 233 | audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 234 | "audit_rate_limit=%d old=%d by auid=%u", |
c94c257c | 235 | audit_rate_limit, old, loginuid); |
1da177e4 LT |
236 | return old; |
237 | } | |
238 | ||
c94c257c | 239 | static int audit_set_backlog_limit(int limit, uid_t loginuid) |
1da177e4 LT |
240 | { |
241 | int old = audit_backlog_limit; | |
242 | audit_backlog_limit = limit; | |
9ad9ad38 | 243 | audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 244 | "audit_backlog_limit=%d old=%d by auid=%u", |
c94c257c | 245 | audit_backlog_limit, old, loginuid); |
1da177e4 LT |
246 | return old; |
247 | } | |
248 | ||
c94c257c | 249 | static int audit_set_enabled(int state, uid_t loginuid) |
1da177e4 LT |
250 | { |
251 | int old = audit_enabled; | |
252 | if (state != 0 && state != 1) | |
253 | return -EINVAL; | |
254 | audit_enabled = state; | |
9ad9ad38 | 255 | audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 256 | "audit_enabled=%d old=%d by auid=%u", |
c0404993 | 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; | |
9ad9ad38 | 269 | audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 270 | "audit_failure=%d old=%d by auid=%u", |
c0404993 | 271 | audit_failure, old, loginuid); |
1da177e4 LT |
272 | return old; |
273 | } | |
274 | ||
97a41e26 | 275 | static int kauditd_thread(void *dummy) |
b7d11258 DW |
276 | { |
277 | struct sk_buff *skb; | |
278 | ||
279 | while (1) { | |
280 | skb = skb_dequeue(&audit_skb_queue); | |
9ad9ad38 | 281 | wake_up(&audit_backlog_wait); |
b7d11258 DW |
282 | if (skb) { |
283 | if (audit_pid) { | |
284 | int err = netlink_unicast(audit_sock, skb, audit_pid, 0); | |
285 | if (err < 0) { | |
286 | BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */ | |
287 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); | |
288 | audit_pid = 0; | |
289 | } | |
290 | } else { | |
e1b09eba | 291 | printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0)); |
b7d11258 DW |
292 | kfree_skb(skb); |
293 | } | |
294 | } else { | |
295 | DECLARE_WAITQUEUE(wait, current); | |
296 | set_current_state(TASK_INTERRUPTIBLE); | |
297 | add_wait_queue(&kauditd_wait, &wait); | |
298 | ||
7a4ae749 PO |
299 | if (!skb_queue_len(&audit_skb_queue)) { |
300 | try_to_freeze(); | |
b7d11258 | 301 | schedule(); |
7a4ae749 | 302 | } |
b7d11258 DW |
303 | |
304 | __set_current_state(TASK_RUNNING); | |
305 | remove_wait_queue(&kauditd_wait, &wait); | |
306 | } | |
307 | } | |
fe7752ba | 308 | return 0; |
b7d11258 DW |
309 | } |
310 | ||
b0dd25a8 RD |
311 | /** |
312 | * audit_send_reply - send an audit reply message via netlink | |
313 | * @pid: process id to send reply to | |
314 | * @seq: sequence number | |
315 | * @type: audit message type | |
316 | * @done: done (last) flag | |
317 | * @multi: multi-part message flag | |
318 | * @payload: payload data | |
319 | * @size: payload size | |
320 | * | |
321 | * Allocates an skb, builds the netlink message, and sends it to the pid. | |
322 | * No failure notifications. | |
323 | */ | |
1da177e4 LT |
324 | void audit_send_reply(int pid, int seq, int type, int done, int multi, |
325 | void *payload, int size) | |
326 | { | |
327 | struct sk_buff *skb; | |
328 | struct nlmsghdr *nlh; | |
329 | int len = NLMSG_SPACE(size); | |
330 | void *data; | |
331 | int flags = multi ? NLM_F_MULTI : 0; | |
332 | int t = done ? NLMSG_DONE : type; | |
333 | ||
334 | skb = alloc_skb(len, GFP_KERNEL); | |
335 | if (!skb) | |
b7d11258 | 336 | return; |
1da177e4 | 337 | |
b7d11258 | 338 | nlh = NLMSG_PUT(skb, pid, seq, t, size); |
1da177e4 LT |
339 | nlh->nlmsg_flags = flags; |
340 | data = NLMSG_DATA(nlh); | |
341 | memcpy(data, payload, size); | |
b7d11258 DW |
342 | |
343 | /* Ignore failure. It'll only happen if the sender goes away, | |
344 | because our timeout is set to infinite. */ | |
345 | netlink_unicast(audit_sock, skb, pid, 0); | |
1da177e4 LT |
346 | return; |
347 | ||
348 | nlmsg_failure: /* Used by NLMSG_PUT */ | |
349 | if (skb) | |
350 | kfree_skb(skb); | |
351 | } | |
352 | ||
353 | /* | |
354 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit | |
355 | * control messages. | |
356 | */ | |
357 | static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type) | |
358 | { | |
359 | int err = 0; | |
360 | ||
361 | switch (msg_type) { | |
362 | case AUDIT_GET: | |
363 | case AUDIT_LIST: | |
364 | case AUDIT_SET: | |
365 | case AUDIT_ADD: | |
366 | case AUDIT_DEL: | |
c2f0c7c3 | 367 | case AUDIT_SIGNAL_INFO: |
1da177e4 LT |
368 | if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL)) |
369 | err = -EPERM; | |
370 | break; | |
05474106 | 371 | case AUDIT_USER: |
209aba03 | 372 | case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG: |
90d526c0 | 373 | case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2: |
1da177e4 LT |
374 | if (!cap_raised(eff_cap, CAP_AUDIT_WRITE)) |
375 | err = -EPERM; | |
376 | break; | |
377 | default: /* bad msg */ | |
378 | err = -EINVAL; | |
379 | } | |
380 | ||
381 | return err; | |
382 | } | |
383 | ||
384 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) | |
385 | { | |
386 | u32 uid, pid, seq; | |
387 | void *data; | |
388 | struct audit_status *status_get, status_set; | |
389 | int err; | |
c0404993 | 390 | struct audit_buffer *ab; |
1da177e4 | 391 | u16 msg_type = nlh->nlmsg_type; |
c94c257c | 392 | uid_t loginuid; /* loginuid of sender */ |
c2f0c7c3 | 393 | struct audit_sig_info sig_data; |
1da177e4 LT |
394 | |
395 | err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type); | |
396 | if (err) | |
397 | return err; | |
398 | ||
b0dd25a8 RD |
399 | /* As soon as there's any sign of userspace auditd, |
400 | * start kauditd to talk to it */ | |
b7d11258 DW |
401 | if (!kauditd_task) |
402 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); | |
403 | if (IS_ERR(kauditd_task)) { | |
404 | err = PTR_ERR(kauditd_task); | |
405 | kauditd_task = NULL; | |
406 | return err; | |
407 | } | |
408 | ||
1da177e4 LT |
409 | pid = NETLINK_CREDS(skb)->pid; |
410 | uid = NETLINK_CREDS(skb)->uid; | |
c94c257c | 411 | loginuid = NETLINK_CB(skb).loginuid; |
1da177e4 LT |
412 | seq = nlh->nlmsg_seq; |
413 | data = NLMSG_DATA(nlh); | |
414 | ||
415 | switch (msg_type) { | |
416 | case AUDIT_GET: | |
417 | status_set.enabled = audit_enabled; | |
418 | status_set.failure = audit_failure; | |
419 | status_set.pid = audit_pid; | |
420 | status_set.rate_limit = audit_rate_limit; | |
421 | status_set.backlog_limit = audit_backlog_limit; | |
422 | status_set.lost = atomic_read(&audit_lost); | |
b7d11258 | 423 | status_set.backlog = skb_queue_len(&audit_skb_queue); |
1da177e4 LT |
424 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, |
425 | &status_set, sizeof(status_set)); | |
426 | break; | |
427 | case AUDIT_SET: | |
428 | if (nlh->nlmsg_len < sizeof(struct audit_status)) | |
429 | return -EINVAL; | |
430 | status_get = (struct audit_status *)data; | |
431 | if (status_get->mask & AUDIT_STATUS_ENABLED) { | |
c94c257c | 432 | err = audit_set_enabled(status_get->enabled, loginuid); |
1da177e4 LT |
433 | if (err < 0) return err; |
434 | } | |
435 | if (status_get->mask & AUDIT_STATUS_FAILURE) { | |
c94c257c | 436 | err = audit_set_failure(status_get->failure, loginuid); |
1da177e4 LT |
437 | if (err < 0) return err; |
438 | } | |
439 | if (status_get->mask & AUDIT_STATUS_PID) { | |
440 | int old = audit_pid; | |
441 | audit_pid = status_get->pid; | |
9ad9ad38 | 442 | audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, |
bccf6ae0 | 443 | "audit_pid=%d old=%d by auid=%u", |
c94c257c | 444 | audit_pid, old, loginuid); |
1da177e4 LT |
445 | } |
446 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) | |
c94c257c | 447 | audit_set_rate_limit(status_get->rate_limit, loginuid); |
1da177e4 | 448 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
c94c257c SH |
449 | audit_set_backlog_limit(status_get->backlog_limit, |
450 | loginuid); | |
1da177e4 | 451 | break; |
05474106 | 452 | case AUDIT_USER: |
209aba03 | 453 | case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG: |
90d526c0 | 454 | case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2: |
4a4cd633 DW |
455 | if (!audit_enabled && msg_type != AUDIT_USER_AVC) |
456 | return 0; | |
457 | ||
5bb289b5 | 458 | err = audit_filter_user(&NETLINK_CB(skb), msg_type); |
4a4cd633 DW |
459 | if (err == 1) { |
460 | err = 0; | |
9ad9ad38 | 461 | ab = audit_log_start(NULL, GFP_KERNEL, msg_type); |
4a4cd633 DW |
462 | if (ab) { |
463 | audit_log_format(ab, | |
464 | "user pid=%d uid=%u auid=%u msg='%.1024s'", | |
465 | pid, uid, loginuid, (char *)data); | |
466 | audit_set_pid(ab, pid); | |
467 | audit_log_end(ab); | |
468 | } | |
0f45aa18 | 469 | } |
1da177e4 LT |
470 | break; |
471 | case AUDIT_ADD: | |
472 | case AUDIT_DEL: | |
473 | if (nlh->nlmsg_len < sizeof(struct audit_rule)) | |
474 | return -EINVAL; | |
475 | /* fallthrough */ | |
476 | case AUDIT_LIST: | |
1da177e4 | 477 | err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid, |
c94c257c | 478 | uid, seq, data, loginuid); |
1da177e4 | 479 | break; |
c2f0c7c3 SG |
480 | case AUDIT_SIGNAL_INFO: |
481 | sig_data.uid = audit_sig_uid; | |
482 | sig_data.pid = audit_sig_pid; | |
483 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, | |
484 | 0, 0, &sig_data, sizeof(sig_data)); | |
485 | break; | |
1da177e4 LT |
486 | default: |
487 | err = -EINVAL; | |
488 | break; | |
489 | } | |
490 | ||
491 | return err < 0 ? err : 0; | |
492 | } | |
493 | ||
b0dd25a8 RD |
494 | /* |
495 | * Get message from skb (based on rtnetlink_rcv_skb). Each message is | |
1da177e4 | 496 | * processed by audit_receive_msg. Malformed skbs with wrong length are |
b0dd25a8 RD |
497 | * discarded silently. |
498 | */ | |
2a0a6ebe | 499 | static void audit_receive_skb(struct sk_buff *skb) |
1da177e4 LT |
500 | { |
501 | int err; | |
502 | struct nlmsghdr *nlh; | |
503 | u32 rlen; | |
504 | ||
505 | while (skb->len >= NLMSG_SPACE(0)) { | |
506 | nlh = (struct nlmsghdr *)skb->data; | |
507 | if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len) | |
2a0a6ebe | 508 | return; |
1da177e4 LT |
509 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
510 | if (rlen > skb->len) | |
511 | rlen = skb->len; | |
512 | if ((err = audit_receive_msg(skb, nlh))) { | |
513 | netlink_ack(skb, nlh, err); | |
514 | } else if (nlh->nlmsg_flags & NLM_F_ACK) | |
515 | netlink_ack(skb, nlh, 0); | |
516 | skb_pull(skb, rlen); | |
517 | } | |
1da177e4 LT |
518 | } |
519 | ||
520 | /* Receive messages from netlink socket. */ | |
521 | static void audit_receive(struct sock *sk, int length) | |
522 | { | |
523 | struct sk_buff *skb; | |
2a0a6ebe | 524 | unsigned int qlen; |
1da177e4 | 525 | |
2a0a6ebe | 526 | down(&audit_netlink_sem); |
1da177e4 | 527 | |
2a0a6ebe HX |
528 | for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) { |
529 | skb = skb_dequeue(&sk->sk_receive_queue); | |
530 | audit_receive_skb(skb); | |
531 | kfree_skb(skb); | |
1da177e4 LT |
532 | } |
533 | up(&audit_netlink_sem); | |
534 | } | |
535 | ||
1da177e4 LT |
536 | |
537 | /* Initialize audit support at boot time. */ | |
538 | static int __init audit_init(void) | |
539 | { | |
540 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", | |
541 | audit_default ? "enabled" : "disabled"); | |
06628607 | 542 | audit_sock = netlink_kernel_create(NETLINK_AUDIT, 0, audit_receive, |
4fdb3bb7 | 543 | THIS_MODULE); |
1da177e4 LT |
544 | if (!audit_sock) |
545 | audit_panic("cannot initialize netlink socket"); | |
546 | ||
b7d11258 DW |
547 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; |
548 | skb_queue_head_init(&audit_skb_queue); | |
1da177e4 LT |
549 | audit_initialized = 1; |
550 | audit_enabled = audit_default; | |
9ad9ad38 | 551 | audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized"); |
1da177e4 LT |
552 | return 0; |
553 | } | |
1da177e4 LT |
554 | __initcall(audit_init); |
555 | ||
556 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ | |
557 | static int __init audit_enable(char *str) | |
558 | { | |
559 | audit_default = !!simple_strtol(str, NULL, 0); | |
560 | printk(KERN_INFO "audit: %s%s\n", | |
561 | audit_default ? "enabled" : "disabled", | |
562 | audit_initialized ? "" : " (after initialization)"); | |
563 | if (audit_initialized) | |
564 | audit_enabled = audit_default; | |
565 | return 0; | |
566 | } | |
567 | ||
568 | __setup("audit=", audit_enable); | |
569 | ||
16e1904e CW |
570 | static void audit_buffer_free(struct audit_buffer *ab) |
571 | { | |
572 | unsigned long flags; | |
573 | ||
8fc6115c CW |
574 | if (!ab) |
575 | return; | |
576 | ||
5ac52f33 CW |
577 | if (ab->skb) |
578 | kfree_skb(ab->skb); | |
b7d11258 | 579 | |
16e1904e CW |
580 | spin_lock_irqsave(&audit_freelist_lock, flags); |
581 | if (++audit_freelist_count > AUDIT_MAXFREE) | |
582 | kfree(ab); | |
583 | else | |
584 | list_add(&ab->list, &audit_freelist); | |
585 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
586 | } | |
587 | ||
c0404993 | 588 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
dd0fc66f | 589 | gfp_t gfp_mask, int type) |
16e1904e CW |
590 | { |
591 | unsigned long flags; | |
592 | struct audit_buffer *ab = NULL; | |
c0404993 | 593 | struct nlmsghdr *nlh; |
16e1904e CW |
594 | |
595 | spin_lock_irqsave(&audit_freelist_lock, flags); | |
596 | if (!list_empty(&audit_freelist)) { | |
597 | ab = list_entry(audit_freelist.next, | |
598 | struct audit_buffer, list); | |
599 | list_del(&ab->list); | |
600 | --audit_freelist_count; | |
601 | } | |
602 | spin_unlock_irqrestore(&audit_freelist_lock, flags); | |
603 | ||
604 | if (!ab) { | |
4332bdd3 | 605 | ab = kmalloc(sizeof(*ab), gfp_mask); |
16e1904e | 606 | if (!ab) |
8fc6115c | 607 | goto err; |
16e1904e | 608 | } |
8fc6115c | 609 | |
4332bdd3 | 610 | ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask); |
5ac52f33 | 611 | if (!ab->skb) |
8fc6115c CW |
612 | goto err; |
613 | ||
b7d11258 | 614 | ab->ctx = ctx; |
9ad9ad38 | 615 | ab->gfp_mask = gfp_mask; |
c0404993 SG |
616 | nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0)); |
617 | nlh->nlmsg_type = type; | |
618 | nlh->nlmsg_flags = 0; | |
619 | nlh->nlmsg_pid = 0; | |
620 | nlh->nlmsg_seq = 0; | |
16e1904e | 621 | return ab; |
8fc6115c CW |
622 | err: |
623 | audit_buffer_free(ab); | |
624 | return NULL; | |
16e1904e | 625 | } |
1da177e4 | 626 | |
b0dd25a8 RD |
627 | /** |
628 | * audit_serial - compute a serial number for the audit record | |
629 | * | |
630 | * Compute a serial number for the audit record. Audit records are | |
bfb4496e DW |
631 | * written to user-space as soon as they are generated, so a complete |
632 | * audit record may be written in several pieces. The timestamp of the | |
633 | * record and this serial number are used by the user-space tools to | |
634 | * determine which pieces belong to the same audit record. The | |
635 | * (timestamp,serial) tuple is unique for each syscall and is live from | |
636 | * syscall entry to syscall exit. | |
637 | * | |
bfb4496e DW |
638 | * NOTE: Another possibility is to store the formatted records off the |
639 | * audit context (for those records that have a context), and emit them | |
640 | * all at syscall exit. However, this could delay the reporting of | |
641 | * significant errors until syscall exit (or never, if the system | |
b0dd25a8 RD |
642 | * halts). |
643 | */ | |
bfb4496e DW |
644 | unsigned int audit_serial(void) |
645 | { | |
d5b454f2 DW |
646 | static spinlock_t serial_lock = SPIN_LOCK_UNLOCKED; |
647 | static unsigned int serial = 0; | |
648 | ||
649 | unsigned long flags; | |
650 | unsigned int ret; | |
bfb4496e | 651 | |
d5b454f2 | 652 | spin_lock_irqsave(&serial_lock, flags); |
bfb4496e | 653 | do { |
ce625a80 DW |
654 | ret = ++serial; |
655 | } while (unlikely(!ret)); | |
d5b454f2 | 656 | spin_unlock_irqrestore(&serial_lock, flags); |
bfb4496e | 657 | |
d5b454f2 | 658 | return ret; |
bfb4496e DW |
659 | } |
660 | ||
661 | static inline void audit_get_stamp(struct audit_context *ctx, | |
662 | struct timespec *t, unsigned int *serial) | |
663 | { | |
664 | if (ctx) | |
665 | auditsc_get_stamp(ctx, t, serial); | |
666 | else { | |
667 | *t = CURRENT_TIME; | |
668 | *serial = audit_serial(); | |
669 | } | |
670 | } | |
671 | ||
1da177e4 LT |
672 | /* Obtain an audit buffer. This routine does locking to obtain the |
673 | * audit buffer, but then no locking is required for calls to | |
674 | * audit_log_*format. If the tsk is a task that is currently in a | |
675 | * syscall, then the syscall is marked as auditable and an audit record | |
676 | * will be written at syscall exit. If there is no associated task, tsk | |
677 | * should be NULL. */ | |
9ad9ad38 | 678 | |
b0dd25a8 RD |
679 | /** |
680 | * audit_log_start - obtain an audit buffer | |
681 | * @ctx: audit_context (may be NULL) | |
682 | * @gfp_mask: type of allocation | |
683 | * @type: audit message type | |
684 | * | |
685 | * Returns audit_buffer pointer on success or NULL on error. | |
686 | * | |
687 | * Obtain an audit buffer. This routine does locking to obtain the | |
688 | * audit buffer, but then no locking is required for calls to | |
689 | * audit_log_*format. If the task (ctx) is a task that is currently in a | |
690 | * syscall, then the syscall is marked as auditable and an audit record | |
691 | * will be written at syscall exit. If there is no associated task, then | |
692 | * task context (ctx) should be NULL. | |
693 | */ | |
9796fdd8 | 694 | struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, |
9ad9ad38 | 695 | int type) |
1da177e4 LT |
696 | { |
697 | struct audit_buffer *ab = NULL; | |
1da177e4 | 698 | struct timespec t; |
d812ddbb | 699 | unsigned int serial; |
9ad9ad38 | 700 | int reserve; |
ac4cec44 | 701 | unsigned long timeout_start = jiffies; |
1da177e4 LT |
702 | |
703 | if (!audit_initialized) | |
704 | return NULL; | |
705 | ||
c8edc80c DK |
706 | if (unlikely(audit_filter_type(type))) |
707 | return NULL; | |
708 | ||
9ad9ad38 DW |
709 | if (gfp_mask & __GFP_WAIT) |
710 | reserve = 0; | |
711 | else | |
712 | reserve = 5; /* Allow atomic callers to go up to five | |
713 | entries over the normal backlog limit */ | |
714 | ||
715 | while (audit_backlog_limit | |
716 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { | |
ac4cec44 DW |
717 | if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time |
718 | && time_before(jiffies, timeout_start + audit_backlog_wait_time)) { | |
719 | ||
9ad9ad38 DW |
720 | /* Wait for auditd to drain the queue a little */ |
721 | DECLARE_WAITQUEUE(wait, current); | |
722 | set_current_state(TASK_INTERRUPTIBLE); | |
723 | add_wait_queue(&audit_backlog_wait, &wait); | |
724 | ||
725 | if (audit_backlog_limit && | |
726 | skb_queue_len(&audit_skb_queue) > audit_backlog_limit) | |
ac4cec44 | 727 | schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies); |
9ad9ad38 DW |
728 | |
729 | __set_current_state(TASK_RUNNING); | |
730 | remove_wait_queue(&audit_backlog_wait, &wait); | |
ac4cec44 | 731 | continue; |
9ad9ad38 | 732 | } |
fb19b4c6 DW |
733 | if (audit_rate_check()) |
734 | printk(KERN_WARNING | |
735 | "audit: audit_backlog=%d > " | |
736 | "audit_backlog_limit=%d\n", | |
737 | skb_queue_len(&audit_skb_queue), | |
738 | audit_backlog_limit); | |
739 | audit_log_lost("backlog limit exceeded"); | |
ac4cec44 DW |
740 | audit_backlog_wait_time = audit_backlog_wait_overflow; |
741 | wake_up(&audit_backlog_wait); | |
fb19b4c6 DW |
742 | return NULL; |
743 | } | |
744 | ||
9ad9ad38 | 745 | ab = audit_buffer_alloc(ctx, gfp_mask, type); |
1da177e4 LT |
746 | if (!ab) { |
747 | audit_log_lost("out of memory in audit_log_start"); | |
748 | return NULL; | |
749 | } | |
750 | ||
bfb4496e | 751 | audit_get_stamp(ab->ctx, &t, &serial); |
197c69c6 | 752 | |
1da177e4 LT |
753 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
754 | t.tv_sec, t.tv_nsec/1000000, serial); | |
755 | return ab; | |
756 | } | |
757 | ||
8fc6115c | 758 | /** |
5ac52f33 | 759 | * audit_expand - expand skb in the audit buffer |
8fc6115c | 760 | * @ab: audit_buffer |
b0dd25a8 | 761 | * @extra: space to add at tail of the skb |
8fc6115c CW |
762 | * |
763 | * Returns 0 (no space) on failed expansion, or available space if | |
764 | * successful. | |
765 | */ | |
e3b926b4 | 766 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
8fc6115c | 767 | { |
5ac52f33 | 768 | struct sk_buff *skb = ab->skb; |
e3b926b4 | 769 | int ret = pskb_expand_head(skb, skb_headroom(skb), extra, |
9ad9ad38 | 770 | ab->gfp_mask); |
5ac52f33 CW |
771 | if (ret < 0) { |
772 | audit_log_lost("out of memory in audit_expand"); | |
8fc6115c | 773 | return 0; |
5ac52f33 CW |
774 | } |
775 | return skb_tailroom(skb); | |
8fc6115c | 776 | } |
1da177e4 | 777 | |
b0dd25a8 RD |
778 | /* |
779 | * Format an audit message into the audit buffer. If there isn't enough | |
1da177e4 LT |
780 | * room in the audit buffer, more room will be allocated and vsnprint |
781 | * will be called a second time. Currently, we assume that a printk | |
b0dd25a8 RD |
782 | * can't format message larger than 1024 bytes, so we don't either. |
783 | */ | |
1da177e4 LT |
784 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, |
785 | va_list args) | |
786 | { | |
787 | int len, avail; | |
5ac52f33 | 788 | struct sk_buff *skb; |
eecb0a73 | 789 | va_list args2; |
1da177e4 LT |
790 | |
791 | if (!ab) | |
792 | return; | |
793 | ||
5ac52f33 CW |
794 | BUG_ON(!ab->skb); |
795 | skb = ab->skb; | |
796 | avail = skb_tailroom(skb); | |
797 | if (avail == 0) { | |
e3b926b4 | 798 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
8fc6115c CW |
799 | if (!avail) |
800 | goto out; | |
1da177e4 | 801 | } |
eecb0a73 | 802 | va_copy(args2, args); |
5ac52f33 | 803 | len = vsnprintf(skb->tail, avail, fmt, args); |
1da177e4 LT |
804 | if (len >= avail) { |
805 | /* The printk buffer is 1024 bytes long, so if we get | |
806 | * here and AUDIT_BUFSIZ is at least 1024, then we can | |
807 | * log everything that printk could have logged. */ | |
b0dd25a8 RD |
808 | avail = audit_expand(ab, |
809 | max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); | |
8fc6115c CW |
810 | if (!avail) |
811 | goto out; | |
eecb0a73 | 812 | len = vsnprintf(skb->tail, avail, fmt, args2); |
1da177e4 | 813 | } |
168b7173 SG |
814 | if (len > 0) |
815 | skb_put(skb, len); | |
8fc6115c CW |
816 | out: |
817 | return; | |
1da177e4 LT |
818 | } |
819 | ||
b0dd25a8 RD |
820 | /** |
821 | * audit_log_format - format a message into the audit buffer. | |
822 | * @ab: audit_buffer | |
823 | * @fmt: format string | |
824 | * @...: optional parameters matching @fmt string | |
825 | * | |
826 | * All the work is done in audit_log_vformat. | |
827 | */ | |
1da177e4 LT |
828 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) |
829 | { | |
830 | va_list args; | |
831 | ||
832 | if (!ab) | |
833 | return; | |
834 | va_start(args, fmt); | |
835 | audit_log_vformat(ab, fmt, args); | |
836 | va_end(args); | |
837 | } | |
838 | ||
b0dd25a8 RD |
839 | /** |
840 | * audit_log_hex - convert a buffer to hex and append it to the audit skb | |
841 | * @ab: the audit_buffer | |
842 | * @buf: buffer to convert to hex | |
843 | * @len: length of @buf to be converted | |
844 | * | |
845 | * No return value; failure to expand is silently ignored. | |
846 | * | |
847 | * This function will take the passed buf and convert it into a string of | |
848 | * ascii hex digits. The new string is placed onto the skb. | |
849 | */ | |
850 | void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, | |
168b7173 | 851 | size_t len) |
83c7d091 | 852 | { |
168b7173 SG |
853 | int i, avail, new_len; |
854 | unsigned char *ptr; | |
855 | struct sk_buff *skb; | |
856 | static const unsigned char *hex = "0123456789ABCDEF"; | |
857 | ||
858 | BUG_ON(!ab->skb); | |
859 | skb = ab->skb; | |
860 | avail = skb_tailroom(skb); | |
861 | new_len = len<<1; | |
862 | if (new_len >= avail) { | |
863 | /* Round the buffer request up to the next multiple */ | |
864 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); | |
865 | avail = audit_expand(ab, new_len); | |
866 | if (!avail) | |
867 | return; | |
868 | } | |
83c7d091 | 869 | |
168b7173 SG |
870 | ptr = skb->tail; |
871 | for (i=0; i<len; i++) { | |
872 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ | |
873 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ | |
874 | } | |
875 | *ptr = 0; | |
876 | skb_put(skb, len << 1); /* new string is twice the old string */ | |
83c7d091 DW |
877 | } |
878 | ||
b0dd25a8 RD |
879 | /** |
880 | * audit_log_unstrustedstring - log a string that may contain random characters | |
881 | * @ab: audit_buffer | |
882 | * @string: string to be logged | |
883 | * | |
884 | * This code will escape a string that is passed to it if the string | |
885 | * contains a control character, unprintable character, double quote mark, | |
168b7173 | 886 | * or a space. Unescaped strings will start and end with a double quote mark. |
b0dd25a8 RD |
887 | * Strings that are escaped are printed in hex (2 digits per char). |
888 | */ | |
83c7d091 DW |
889 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) |
890 | { | |
81b7854d | 891 | const unsigned char *p = string; |
83c7d091 DW |
892 | |
893 | while (*p) { | |
168b7173 | 894 | if (*p == '"' || *p < 0x21 || *p > 0x7f) { |
83c7d091 DW |
895 | audit_log_hex(ab, string, strlen(string)); |
896 | return; | |
897 | } | |
898 | p++; | |
899 | } | |
900 | audit_log_format(ab, "\"%s\"", string); | |
901 | } | |
902 | ||
168b7173 | 903 | /* This is a helper-function to print the escaped d_path */ |
1da177e4 LT |
904 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, |
905 | struct dentry *dentry, struct vfsmount *vfsmnt) | |
906 | { | |
168b7173 | 907 | char *p, *path; |
1da177e4 | 908 | |
8fc6115c CW |
909 | if (prefix) |
910 | audit_log_format(ab, " %s", prefix); | |
1da177e4 | 911 | |
168b7173 | 912 | /* We will allow 11 spaces for ' (deleted)' to be appended */ |
9ad9ad38 | 913 | path = kmalloc(PATH_MAX+11, ab->gfp_mask); |
168b7173 SG |
914 | if (!path) { |
915 | audit_log_format(ab, "<no memory>"); | |
916 | return; | |
1da177e4 | 917 | } |
168b7173 SG |
918 | p = d_path(dentry, vfsmnt, path, PATH_MAX+11); |
919 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ | |
920 | /* FIXME: can we save some information here? */ | |
921 | audit_log_format(ab, "<too long>"); | |
922 | } else | |
923 | audit_log_untrustedstring(ab, p); | |
924 | kfree(path); | |
1da177e4 LT |
925 | } |
926 | ||
b0dd25a8 RD |
927 | /** |
928 | * audit_log_end - end one audit record | |
929 | * @ab: the audit_buffer | |
930 | * | |
931 | * The netlink_* functions cannot be called inside an irq context, so | |
932 | * the audit buffer is placed on a queue and a tasklet is scheduled to | |
1da177e4 | 933 | * remove them from the queue outside the irq context. May be called in |
b0dd25a8 RD |
934 | * any context. |
935 | */ | |
b7d11258 | 936 | void audit_log_end(struct audit_buffer *ab) |
1da177e4 | 937 | { |
1da177e4 LT |
938 | if (!ab) |
939 | return; | |
940 | if (!audit_rate_check()) { | |
941 | audit_log_lost("rate limit exceeded"); | |
942 | } else { | |
b7d11258 DW |
943 | if (audit_pid) { |
944 | struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data; | |
945 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); | |
946 | skb_queue_tail(&audit_skb_queue, ab->skb); | |
947 | ab->skb = NULL; | |
948 | wake_up_interruptible(&kauditd_wait); | |
949 | } else { | |
e1b09eba | 950 | printk(KERN_NOTICE "%s\n", ab->skb->data + NLMSG_SPACE(0)); |
b7d11258 | 951 | } |
1da177e4 | 952 | } |
16e1904e | 953 | audit_buffer_free(ab); |
1da177e4 LT |
954 | } |
955 | ||
b0dd25a8 RD |
956 | /** |
957 | * audit_log - Log an audit record | |
958 | * @ctx: audit context | |
959 | * @gfp_mask: type of allocation | |
960 | * @type: audit message type | |
961 | * @fmt: format string to use | |
962 | * @...: variable parameters matching the format string | |
963 | * | |
964 | * This is a convenience function that calls audit_log_start, | |
965 | * audit_log_vformat, and audit_log_end. It may be called | |
966 | * in any context. | |
967 | */ | |
9796fdd8 | 968 | void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, |
9ad9ad38 | 969 | const char *fmt, ...) |
1da177e4 LT |
970 | { |
971 | struct audit_buffer *ab; | |
972 | va_list args; | |
973 | ||
9ad9ad38 | 974 | ab = audit_log_start(ctx, gfp_mask, type); |
1da177e4 LT |
975 | if (ab) { |
976 | va_start(args, fmt); | |
977 | audit_log_vformat(ab, fmt, args); | |
978 | va_end(args); | |
979 | audit_log_end(ab); | |
980 | } | |
981 | } |