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1 | /* audit.c -- Auditing support |
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 2003-2007 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 Security Modules. |
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 | * |
41 | * Example user-space utilities: http://people.redhat.com/sgrubb/audit/ |
42 | */ |
43 | |
44 | #include <linux/init.h> |
45 | #include <asm/types.h> |
46 | #include <asm/atomic.h> |
47 | #include <linux/mm.h> |
48 | #include <linux/module.h> |
49 | #include <linux/slab.h> |
50 | #include <linux/err.h> |
51 | #include <linux/kthread.h> |
52 | |
53 | #include <linux/audit.h> |
54 | |
55 | #include <net/sock.h> |
56 | #include <net/netlink.h> |
57 | #include <linux/skbuff.h> |
58 | #include <linux/netlink.h> |
59 | #include <linux/freezer.h> |
60 | #include <linux/tty.h> |
61 | |
62 | #include "audit.h" |
63 | |
64 | /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED. |
65 | * (Initialization happens after skb_init is called.) */ |
66 | #define AUDIT_DISABLED -1 |
67 | #define AUDIT_UNINITIALIZED 0 |
68 | #define AUDIT_INITIALIZED 1 |
69 | static int audit_initialized; |
70 | |
71 | #define AUDIT_OFF 0 |
72 | #define AUDIT_ON 1 |
73 | #define AUDIT_LOCKED 2 |
74 | int audit_enabled; |
75 | int audit_ever_enabled; |
76 | |
77 | EXPORT_SYMBOL_GPL(audit_enabled); |
78 | |
79 | /* Default state when kernel boots without any parameters. */ |
80 | static int audit_default; |
81 | |
82 | /* If auditing cannot proceed, audit_failure selects what happens. */ |
83 | static int audit_failure = AUDIT_FAIL_PRINTK; |
84 | |
85 | /* |
86 | * If audit records are to be written to the netlink socket, audit_pid |
87 | * contains the pid of the auditd process and audit_nlk_pid contains |
88 | * the pid to use to send netlink messages to that process. |
89 | */ |
90 | int audit_pid; |
91 | static int audit_nlk_pid; |
92 | |
93 | /* If audit_rate_limit is non-zero, limit the rate of sending audit records |
94 | * to that number per second. This prevents DoS attacks, but results in |
95 | * audit records being dropped. */ |
96 | static int audit_rate_limit; |
97 | |
98 | /* Number of outstanding audit_buffers allowed. */ |
99 | static int audit_backlog_limit = 64; |
100 | static int audit_backlog_wait_time = 60 * HZ; |
101 | static int audit_backlog_wait_overflow = 0; |
102 | |
103 | /* The identity of the user shutting down the audit system. */ |
104 | uid_t audit_sig_uid = -1; |
105 | pid_t audit_sig_pid = -1; |
106 | u32 audit_sig_sid = 0; |
107 | |
108 | /* Records can be lost in several ways: |
109 | 0) [suppressed in audit_alloc] |
110 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] |
111 | 2) out of memory in audit_log_move [alloc_skb] |
112 | 3) suppressed due to audit_rate_limit |
113 | 4) suppressed due to audit_backlog_limit |
114 | */ |
115 | static atomic_t audit_lost = ATOMIC_INIT(0); |
116 | |
117 | /* The netlink socket. */ |
118 | static struct sock *audit_sock; |
119 | |
120 | /* Hash for inode-based rules */ |
121 | struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; |
122 | |
123 | /* The audit_freelist is a list of pre-allocated audit buffers (if more |
124 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of |
125 | * being placed on the freelist). */ |
126 | static DEFINE_SPINLOCK(audit_freelist_lock); |
127 | static int audit_freelist_count; |
128 | static LIST_HEAD(audit_freelist); |
129 | |
130 | static struct sk_buff_head audit_skb_queue; |
131 | /* queue of skbs to send to auditd when/if it comes back */ |
132 | static struct sk_buff_head audit_skb_hold_queue; |
133 | static struct task_struct *kauditd_task; |
134 | static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); |
135 | static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); |
136 | |
137 | /* Serialize requests from userspace. */ |
138 | DEFINE_MUTEX(audit_cmd_mutex); |
139 | |
140 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting |
141 | * audit records. Since printk uses a 1024 byte buffer, this buffer |
142 | * should be at least that large. */ |
143 | #define AUDIT_BUFSIZ 1024 |
144 | |
145 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the |
146 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ |
147 | #define AUDIT_MAXFREE (2*NR_CPUS) |
148 | |
149 | /* The audit_buffer is used when formatting an audit record. The caller |
150 | * locks briefly to get the record off the freelist or to allocate the |
151 | * buffer, and locks briefly to send the buffer to the netlink layer or |
152 | * to place it on a transmit queue. Multiple audit_buffers can be in |
153 | * use simultaneously. */ |
154 | struct audit_buffer { |
155 | struct list_head list; |
156 | struct sk_buff *skb; /* formatted skb ready to send */ |
157 | struct audit_context *ctx; /* NULL or associated context */ |
158 | gfp_t gfp_mask; |
159 | }; |
160 | |
161 | struct audit_reply { |
162 | int pid; |
163 | struct sk_buff *skb; |
164 | }; |
165 | |
166 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
167 | { |
168 | if (ab) { |
169 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); |
170 | nlh->nlmsg_pid = pid; |
171 | } |
172 | } |
173 | |
174 | void audit_panic(const char *message) |
175 | { |
176 | switch (audit_failure) |
177 | { |
178 | case AUDIT_FAIL_SILENT: |
179 | break; |
180 | case AUDIT_FAIL_PRINTK: |
181 | if (printk_ratelimit()) |
182 | printk(KERN_ERR "audit: %s\n", message); |
183 | break; |
184 | case AUDIT_FAIL_PANIC: |
185 | /* test audit_pid since printk is always losey, why bother? */ |
186 | if (audit_pid) |
187 | panic("audit: %s\n", message); |
188 | break; |
189 | } |
190 | } |
191 | |
192 | static inline int audit_rate_check(void) |
193 | { |
194 | static unsigned long last_check = 0; |
195 | static int messages = 0; |
196 | static DEFINE_SPINLOCK(lock); |
197 | unsigned long flags; |
198 | unsigned long now; |
199 | unsigned long elapsed; |
200 | int retval = 0; |
201 | |
202 | if (!audit_rate_limit) return 1; |
203 | |
204 | spin_lock_irqsave(&lock, flags); |
205 | if (++messages < audit_rate_limit) { |
206 | retval = 1; |
207 | } else { |
208 | now = jiffies; |
209 | elapsed = now - last_check; |
210 | if (elapsed > HZ) { |
211 | last_check = now; |
212 | messages = 0; |
213 | retval = 1; |
214 | } |
215 | } |
216 | spin_unlock_irqrestore(&lock, flags); |
217 | |
218 | return retval; |
219 | } |
220 | |
221 | /** |
222 | * audit_log_lost - conditionally log lost audit message event |
223 | * @message: the message stating reason for lost audit message |
224 | * |
225 | * Emit at least 1 message per second, even if audit_rate_check is |
226 | * throttling. |
227 | * Always increment the lost messages counter. |
228 | */ |
229 | void audit_log_lost(const char *message) |
230 | { |
231 | static unsigned long last_msg = 0; |
232 | static DEFINE_SPINLOCK(lock); |
233 | unsigned long flags; |
234 | unsigned long now; |
235 | int print; |
236 | |
237 | atomic_inc(&audit_lost); |
238 | |
239 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); |
240 | |
241 | if (!print) { |
242 | spin_lock_irqsave(&lock, flags); |
243 | now = jiffies; |
244 | if (now - last_msg > HZ) { |
245 | print = 1; |
246 | last_msg = now; |
247 | } |
248 | spin_unlock_irqrestore(&lock, flags); |
249 | } |
250 | |
251 | if (print) { |
252 | if (printk_ratelimit()) |
253 | printk(KERN_WARNING |
254 | "audit: audit_lost=%d audit_rate_limit=%d " |
255 | "audit_backlog_limit=%d\n", |
256 | atomic_read(&audit_lost), |
257 | audit_rate_limit, |
258 | audit_backlog_limit); |
259 | audit_panic(message); |
260 | } |
261 | } |
262 | |
263 | static int audit_log_config_change(char *function_name, int new, int old, |
264 | uid_t loginuid, u32 sessionid, u32 sid, |
265 | int allow_changes) |
266 | { |
267 | struct audit_buffer *ab; |
268 | int rc = 0; |
269 | |
270 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); |
271 | audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new, |
272 | old, loginuid, sessionid); |
273 | if (sid) { |
274 | char *ctx = NULL; |
275 | u32 len; |
276 | |
277 | rc = security_secid_to_secctx(sid, &ctx, &len); |
278 | if (rc) { |
279 | audit_log_format(ab, " sid=%u", sid); |
280 | allow_changes = 0; /* Something weird, deny request */ |
281 | } else { |
282 | audit_log_format(ab, " subj=%s", ctx); |
283 | security_release_secctx(ctx, len); |
284 | } |
285 | } |
286 | audit_log_format(ab, " res=%d", allow_changes); |
287 | audit_log_end(ab); |
288 | return rc; |
289 | } |
290 | |
291 | static int audit_do_config_change(char *function_name, int *to_change, |
292 | int new, uid_t loginuid, u32 sessionid, |
293 | u32 sid) |
294 | { |
295 | int allow_changes, rc = 0, old = *to_change; |
296 | |
297 | /* check if we are locked */ |
298 | if (audit_enabled == AUDIT_LOCKED) |
299 | allow_changes = 0; |
300 | else |
301 | allow_changes = 1; |
302 | |
303 | if (audit_enabled != AUDIT_OFF) { |
304 | rc = audit_log_config_change(function_name, new, old, loginuid, |
305 | sessionid, sid, allow_changes); |
306 | if (rc) |
307 | allow_changes = 0; |
308 | } |
309 | |
310 | /* If we are allowed, make the change */ |
311 | if (allow_changes == 1) |
312 | *to_change = new; |
313 | /* Not allowed, update reason */ |
314 | else if (rc == 0) |
315 | rc = -EPERM; |
316 | return rc; |
317 | } |
318 | |
319 | static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid, |
320 | u32 sid) |
321 | { |
322 | return audit_do_config_change("audit_rate_limit", &audit_rate_limit, |
323 | limit, loginuid, sessionid, sid); |
324 | } |
325 | |
326 | static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid, |
327 | u32 sid) |
328 | { |
329 | return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, |
330 | limit, loginuid, sessionid, sid); |
331 | } |
332 | |
333 | static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid) |
334 | { |
335 | int rc; |
336 | if (state < AUDIT_OFF || state > AUDIT_LOCKED) |
337 | return -EINVAL; |
338 | |
339 | rc = audit_do_config_change("audit_enabled", &audit_enabled, state, |
340 | loginuid, sessionid, sid); |
341 | |
342 | if (!rc) |
343 | audit_ever_enabled |= !!state; |
344 | |
345 | return rc; |
346 | } |
347 | |
348 | static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid) |
349 | { |
350 | if (state != AUDIT_FAIL_SILENT |
351 | && state != AUDIT_FAIL_PRINTK |
352 | && state != AUDIT_FAIL_PANIC) |
353 | return -EINVAL; |
354 | |
355 | return audit_do_config_change("audit_failure", &audit_failure, state, |
356 | loginuid, sessionid, sid); |
357 | } |
358 | |
359 | /* |
360 | * Queue skbs to be sent to auditd when/if it comes back. These skbs should |
361 | * already have been sent via prink/syslog and so if these messages are dropped |
362 | * it is not a huge concern since we already passed the audit_log_lost() |
363 | * notification and stuff. This is just nice to get audit messages during |
364 | * boot before auditd is running or messages generated while auditd is stopped. |
365 | * This only holds messages is audit_default is set, aka booting with audit=1 |
366 | * or building your kernel that way. |
367 | */ |
368 | static void audit_hold_skb(struct sk_buff *skb) |
369 | { |
370 | if (audit_default && |
371 | skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit) |
372 | skb_queue_tail(&audit_skb_hold_queue, skb); |
373 | else |
374 | kfree_skb(skb); |
375 | } |
376 | |
377 | /* |
378 | * For one reason or another this nlh isn't getting delivered to the userspace |
379 | * audit daemon, just send it to printk. |
380 | */ |
381 | static void audit_printk_skb(struct sk_buff *skb) |
382 | { |
383 | struct nlmsghdr *nlh = nlmsg_hdr(skb); |
384 | char *data = NLMSG_DATA(nlh); |
385 | |
386 | if (nlh->nlmsg_type != AUDIT_EOE) { |
387 | if (printk_ratelimit()) |
388 | printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data); |
389 | else |
390 | audit_log_lost("printk limit exceeded\n"); |
391 | } |
392 | |
393 | audit_hold_skb(skb); |
394 | } |
395 | |
396 | static void kauditd_send_skb(struct sk_buff *skb) |
397 | { |
398 | int err; |
399 | /* take a reference in case we can't send it and we want to hold it */ |
400 | skb_get(skb); |
401 | err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0); |
402 | if (err < 0) { |
403 | BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */ |
404 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); |
405 | audit_log_lost("auditd disappeared\n"); |
406 | audit_pid = 0; |
407 | /* we might get lucky and get this in the next auditd */ |
408 | audit_hold_skb(skb); |
409 | } else |
410 | /* drop the extra reference if sent ok */ |
411 | consume_skb(skb); |
412 | } |
413 | |
414 | static int kauditd_thread(void *dummy) |
415 | { |
416 | struct sk_buff *skb; |
417 | |
418 | set_freezable(); |
419 | while (!kthread_should_stop()) { |
420 | /* |
421 | * if auditd just started drain the queue of messages already |
422 | * sent to syslog/printk. remember loss here is ok. we already |
423 | * called audit_log_lost() if it didn't go out normally. so the |
424 | * race between the skb_dequeue and the next check for audit_pid |
425 | * doesn't matter. |
426 | * |
427 | * if you ever find kauditd to be too slow we can get a perf win |
428 | * by doing our own locking and keeping better track if there |
429 | * are messages in this queue. I don't see the need now, but |
430 | * in 5 years when I want to play with this again I'll see this |
431 | * note and still have no friggin idea what i'm thinking today. |
432 | */ |
433 | if (audit_default && audit_pid) { |
434 | skb = skb_dequeue(&audit_skb_hold_queue); |
435 | if (unlikely(skb)) { |
436 | while (skb && audit_pid) { |
437 | kauditd_send_skb(skb); |
438 | skb = skb_dequeue(&audit_skb_hold_queue); |
439 | } |
440 | } |
441 | } |
442 | |
443 | skb = skb_dequeue(&audit_skb_queue); |
444 | wake_up(&audit_backlog_wait); |
445 | if (skb) { |
446 | if (audit_pid) |
447 | kauditd_send_skb(skb); |
448 | else |
449 | audit_printk_skb(skb); |
450 | } else { |
451 | DECLARE_WAITQUEUE(wait, current); |
452 | set_current_state(TASK_INTERRUPTIBLE); |
453 | add_wait_queue(&kauditd_wait, &wait); |
454 | |
455 | if (!skb_queue_len(&audit_skb_queue)) { |
456 | try_to_freeze(); |
457 | schedule(); |
458 | } |
459 | |
460 | __set_current_state(TASK_RUNNING); |
461 | remove_wait_queue(&kauditd_wait, &wait); |
462 | } |
463 | } |
464 | return 0; |
465 | } |
466 | |
467 | static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid) |
468 | { |
469 | struct task_struct *tsk; |
470 | int err; |
471 | |
472 | rcu_read_lock(); |
473 | tsk = find_task_by_vpid(pid); |
474 | if (!tsk) { |
475 | rcu_read_unlock(); |
476 | return -ESRCH; |
477 | } |
478 | get_task_struct(tsk); |
479 | rcu_read_unlock(); |
480 | err = tty_audit_push_task(tsk, loginuid, sessionid); |
481 | put_task_struct(tsk); |
482 | return err; |
483 | } |
484 | |
485 | int audit_send_list(void *_dest) |
486 | { |
487 | struct audit_netlink_list *dest = _dest; |
488 | int pid = dest->pid; |
489 | struct sk_buff *skb; |
490 | |
491 | /* wait for parent to finish and send an ACK */ |
492 | mutex_lock(&audit_cmd_mutex); |
493 | mutex_unlock(&audit_cmd_mutex); |
494 | |
495 | while ((skb = __skb_dequeue(&dest->q)) != NULL) |
496 | netlink_unicast(audit_sock, skb, pid, 0); |
497 | |
498 | kfree(dest); |
499 | |
500 | return 0; |
501 | } |
502 | |
503 | struct sk_buff *audit_make_reply(int pid, int seq, int type, int done, |
504 | int multi, const void *payload, int size) |
505 | { |
506 | struct sk_buff *skb; |
507 | struct nlmsghdr *nlh; |
508 | void *data; |
509 | int flags = multi ? NLM_F_MULTI : 0; |
510 | int t = done ? NLMSG_DONE : type; |
511 | |
512 | skb = nlmsg_new(size, GFP_KERNEL); |
513 | if (!skb) |
514 | return NULL; |
515 | |
516 | nlh = NLMSG_NEW(skb, pid, seq, t, size, flags); |
517 | data = NLMSG_DATA(nlh); |
518 | memcpy(data, payload, size); |
519 | return skb; |
520 | |
521 | nlmsg_failure: /* Used by NLMSG_NEW */ |
522 | if (skb) |
523 | kfree_skb(skb); |
524 | return NULL; |
525 | } |
526 | |
527 | static int audit_send_reply_thread(void *arg) |
528 | { |
529 | struct audit_reply *reply = (struct audit_reply *)arg; |
530 | |
531 | mutex_lock(&audit_cmd_mutex); |
532 | mutex_unlock(&audit_cmd_mutex); |
533 | |
534 | /* Ignore failure. It'll only happen if the sender goes away, |
535 | because our timeout is set to infinite. */ |
536 | netlink_unicast(audit_sock, reply->skb, reply->pid, 0); |
537 | kfree(reply); |
538 | return 0; |
539 | } |
540 | /** |
541 | * audit_send_reply - send an audit reply message via netlink |
542 | * @pid: process id to send reply to |
543 | * @seq: sequence number |
544 | * @type: audit message type |
545 | * @done: done (last) flag |
546 | * @multi: multi-part message flag |
547 | * @payload: payload data |
548 | * @size: payload size |
549 | * |
550 | * Allocates an skb, builds the netlink message, and sends it to the pid. |
551 | * No failure notifications. |
552 | */ |
553 | static void audit_send_reply(int pid, int seq, int type, int done, int multi, |
554 | const void *payload, int size) |
555 | { |
556 | struct sk_buff *skb; |
557 | struct task_struct *tsk; |
558 | struct audit_reply *reply = kmalloc(sizeof(struct audit_reply), |
559 | GFP_KERNEL); |
560 | |
561 | if (!reply) |
562 | return; |
563 | |
564 | skb = audit_make_reply(pid, seq, type, done, multi, payload, size); |
565 | if (!skb) |
566 | goto out; |
567 | |
568 | reply->pid = pid; |
569 | reply->skb = skb; |
570 | |
571 | tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); |
572 | if (!IS_ERR(tsk)) |
573 | return; |
574 | kfree_skb(skb); |
575 | out: |
576 | kfree(reply); |
577 | } |
578 | |
579 | /* |
580 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit |
581 | * control messages. |
582 | */ |
583 | static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) |
584 | { |
585 | int err = 0; |
586 | |
587 | switch (msg_type) { |
588 | case AUDIT_GET: |
589 | case AUDIT_LIST: |
590 | case AUDIT_LIST_RULES: |
591 | case AUDIT_SET: |
592 | case AUDIT_ADD: |
593 | case AUDIT_ADD_RULE: |
594 | case AUDIT_DEL: |
595 | case AUDIT_DEL_RULE: |
596 | case AUDIT_SIGNAL_INFO: |
597 | case AUDIT_TTY_GET: |
598 | case AUDIT_TTY_SET: |
599 | case AUDIT_TRIM: |
600 | case AUDIT_MAKE_EQUIV: |
601 | if (security_netlink_recv(skb, CAP_AUDIT_CONTROL)) |
602 | err = -EPERM; |
603 | break; |
604 | case AUDIT_USER: |
605 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: |
606 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: |
607 | if (security_netlink_recv(skb, CAP_AUDIT_WRITE)) |
608 | err = -EPERM; |
609 | break; |
610 | default: /* bad msg */ |
611 | err = -EINVAL; |
612 | } |
613 | |
614 | return err; |
615 | } |
616 | |
617 | static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type, |
618 | u32 pid, u32 uid, uid_t auid, u32 ses, |
619 | u32 sid) |
620 | { |
621 | int rc = 0; |
622 | char *ctx = NULL; |
623 | u32 len; |
624 | |
625 | if (!audit_enabled) { |
626 | *ab = NULL; |
627 | return rc; |
628 | } |
629 | |
630 | *ab = audit_log_start(NULL, GFP_KERNEL, msg_type); |
631 | audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u", |
632 | pid, uid, auid, ses); |
633 | if (sid) { |
634 | rc = security_secid_to_secctx(sid, &ctx, &len); |
635 | if (rc) |
636 | audit_log_format(*ab, " ssid=%u", sid); |
637 | else { |
638 | audit_log_format(*ab, " subj=%s", ctx); |
639 | security_release_secctx(ctx, len); |
640 | } |
641 | } |
642 | |
643 | return rc; |
644 | } |
645 | |
646 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) |
647 | { |
648 | u32 uid, pid, seq, sid; |
649 | void *data; |
650 | struct audit_status *status_get, status_set; |
651 | int err; |
652 | struct audit_buffer *ab; |
653 | u16 msg_type = nlh->nlmsg_type; |
654 | uid_t loginuid; /* loginuid of sender */ |
655 | u32 sessionid; |
656 | struct audit_sig_info *sig_data; |
657 | char *ctx = NULL; |
658 | u32 len; |
659 | |
660 | err = audit_netlink_ok(skb, msg_type); |
661 | if (err) |
662 | return err; |
663 | |
664 | /* As soon as there's any sign of userspace auditd, |
665 | * start kauditd to talk to it */ |
666 | if (!kauditd_task) |
667 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); |
668 | if (IS_ERR(kauditd_task)) { |
669 | err = PTR_ERR(kauditd_task); |
670 | kauditd_task = NULL; |
671 | return err; |
672 | } |
673 | |
674 | pid = NETLINK_CREDS(skb)->pid; |
675 | uid = NETLINK_CREDS(skb)->uid; |
676 | loginuid = audit_get_loginuid(current); |
677 | sessionid = audit_get_sessionid(current); |
678 | security_task_getsecid(current, &sid); |
679 | seq = nlh->nlmsg_seq; |
680 | data = NLMSG_DATA(nlh); |
681 | |
682 | switch (msg_type) { |
683 | case AUDIT_GET: |
684 | status_set.enabled = audit_enabled; |
685 | status_set.failure = audit_failure; |
686 | status_set.pid = audit_pid; |
687 | status_set.rate_limit = audit_rate_limit; |
688 | status_set.backlog_limit = audit_backlog_limit; |
689 | status_set.lost = atomic_read(&audit_lost); |
690 | status_set.backlog = skb_queue_len(&audit_skb_queue); |
691 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, |
692 | &status_set, sizeof(status_set)); |
693 | break; |
694 | case AUDIT_SET: |
695 | if (nlh->nlmsg_len < sizeof(struct audit_status)) |
696 | return -EINVAL; |
697 | status_get = (struct audit_status *)data; |
698 | if (status_get->mask & AUDIT_STATUS_ENABLED) { |
699 | err = audit_set_enabled(status_get->enabled, |
700 | loginuid, sessionid, sid); |
701 | if (err < 0) |
702 | return err; |
703 | } |
704 | if (status_get->mask & AUDIT_STATUS_FAILURE) { |
705 | err = audit_set_failure(status_get->failure, |
706 | loginuid, sessionid, sid); |
707 | if (err < 0) |
708 | return err; |
709 | } |
710 | if (status_get->mask & AUDIT_STATUS_PID) { |
711 | int new_pid = status_get->pid; |
712 | |
713 | if (audit_enabled != AUDIT_OFF) |
714 | audit_log_config_change("audit_pid", new_pid, |
715 | audit_pid, loginuid, |
716 | sessionid, sid, 1); |
717 | |
718 | audit_pid = new_pid; |
719 | audit_nlk_pid = NETLINK_CB(skb).pid; |
720 | } |
721 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) { |
722 | err = audit_set_rate_limit(status_get->rate_limit, |
723 | loginuid, sessionid, sid); |
724 | if (err < 0) |
725 | return err; |
726 | } |
727 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
728 | err = audit_set_backlog_limit(status_get->backlog_limit, |
729 | loginuid, sessionid, sid); |
730 | break; |
731 | case AUDIT_USER: |
732 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: |
733 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: |
734 | if (!audit_enabled && msg_type != AUDIT_USER_AVC) |
735 | return 0; |
736 | |
737 | err = audit_filter_user(&NETLINK_CB(skb)); |
738 | if (err == 1) { |
739 | err = 0; |
740 | if (msg_type == AUDIT_USER_TTY) { |
741 | err = audit_prepare_user_tty(pid, loginuid, |
742 | sessionid); |
743 | if (err) |
744 | break; |
745 | } |
746 | audit_log_common_recv_msg(&ab, msg_type, pid, uid, |
747 | loginuid, sessionid, sid); |
748 | |
749 | if (msg_type != AUDIT_USER_TTY) |
750 | audit_log_format(ab, " msg='%.1024s'", |
751 | (char *)data); |
752 | else { |
753 | int size; |
754 | |
755 | audit_log_format(ab, " msg="); |
756 | size = nlmsg_len(nlh); |
757 | if (size > 0 && |
758 | ((unsigned char *)data)[size - 1] == '\0') |
759 | size--; |
760 | audit_log_n_untrustedstring(ab, data, size); |
761 | } |
762 | audit_set_pid(ab, pid); |
763 | audit_log_end(ab); |
764 | } |
765 | break; |
766 | case AUDIT_ADD: |
767 | case AUDIT_DEL: |
768 | if (nlmsg_len(nlh) < sizeof(struct audit_rule)) |
769 | return -EINVAL; |
770 | if (audit_enabled == AUDIT_LOCKED) { |
771 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
772 | uid, loginuid, sessionid, sid); |
773 | |
774 | audit_log_format(ab, " audit_enabled=%d res=0", |
775 | audit_enabled); |
776 | audit_log_end(ab); |
777 | return -EPERM; |
778 | } |
779 | /* fallthrough */ |
780 | case AUDIT_LIST: |
781 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, |
782 | uid, seq, data, nlmsg_len(nlh), |
783 | loginuid, sessionid, sid); |
784 | break; |
785 | case AUDIT_ADD_RULE: |
786 | case AUDIT_DEL_RULE: |
787 | if (nlmsg_len(nlh) < sizeof(struct audit_rule_data)) |
788 | return -EINVAL; |
789 | if (audit_enabled == AUDIT_LOCKED) { |
790 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
791 | uid, loginuid, sessionid, sid); |
792 | |
793 | audit_log_format(ab, " audit_enabled=%d res=0", |
794 | audit_enabled); |
795 | audit_log_end(ab); |
796 | return -EPERM; |
797 | } |
798 | /* fallthrough */ |
799 | case AUDIT_LIST_RULES: |
800 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, |
801 | uid, seq, data, nlmsg_len(nlh), |
802 | loginuid, sessionid, sid); |
803 | break; |
804 | case AUDIT_TRIM: |
805 | audit_trim_trees(); |
806 | |
807 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
808 | uid, loginuid, sessionid, sid); |
809 | |
810 | audit_log_format(ab, " op=trim res=1"); |
811 | audit_log_end(ab); |
812 | break; |
813 | case AUDIT_MAKE_EQUIV: { |
814 | void *bufp = data; |
815 | u32 sizes[2]; |
816 | size_t msglen = nlmsg_len(nlh); |
817 | char *old, *new; |
818 | |
819 | err = -EINVAL; |
820 | if (msglen < 2 * sizeof(u32)) |
821 | break; |
822 | memcpy(sizes, bufp, 2 * sizeof(u32)); |
823 | bufp += 2 * sizeof(u32); |
824 | msglen -= 2 * sizeof(u32); |
825 | old = audit_unpack_string(&bufp, &msglen, sizes[0]); |
826 | if (IS_ERR(old)) { |
827 | err = PTR_ERR(old); |
828 | break; |
829 | } |
830 | new = audit_unpack_string(&bufp, &msglen, sizes[1]); |
831 | if (IS_ERR(new)) { |
832 | err = PTR_ERR(new); |
833 | kfree(old); |
834 | break; |
835 | } |
836 | /* OK, here comes... */ |
837 | err = audit_tag_tree(old, new); |
838 | |
839 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
840 | uid, loginuid, sessionid, sid); |
841 | |
842 | audit_log_format(ab, " op=make_equiv old="); |
843 | audit_log_untrustedstring(ab, old); |
844 | audit_log_format(ab, " new="); |
845 | audit_log_untrustedstring(ab, new); |
846 | audit_log_format(ab, " res=%d", !err); |
847 | audit_log_end(ab); |
848 | kfree(old); |
849 | kfree(new); |
850 | break; |
851 | } |
852 | case AUDIT_SIGNAL_INFO: |
853 | len = 0; |
854 | if (audit_sig_sid) { |
855 | err = security_secid_to_secctx(audit_sig_sid, &ctx, &len); |
856 | if (err) |
857 | return err; |
858 | } |
859 | sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL); |
860 | if (!sig_data) { |
861 | if (audit_sig_sid) |
862 | security_release_secctx(ctx, len); |
863 | return -ENOMEM; |
864 | } |
865 | sig_data->uid = audit_sig_uid; |
866 | sig_data->pid = audit_sig_pid; |
867 | if (audit_sig_sid) { |
868 | memcpy(sig_data->ctx, ctx, len); |
869 | security_release_secctx(ctx, len); |
870 | } |
871 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, |
872 | 0, 0, sig_data, sizeof(*sig_data) + len); |
873 | kfree(sig_data); |
874 | break; |
875 | case AUDIT_TTY_GET: { |
876 | struct audit_tty_status s; |
877 | struct task_struct *tsk; |
878 | unsigned long flags; |
879 | |
880 | rcu_read_lock(); |
881 | tsk = find_task_by_vpid(pid); |
882 | if (tsk && lock_task_sighand(tsk, &flags)) { |
883 | s.enabled = tsk->signal->audit_tty != 0; |
884 | unlock_task_sighand(tsk, &flags); |
885 | } else |
886 | err = -ESRCH; |
887 | rcu_read_unlock(); |
888 | |
889 | if (!err) |
890 | audit_send_reply(NETLINK_CB(skb).pid, seq, |
891 | AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); |
892 | break; |
893 | } |
894 | case AUDIT_TTY_SET: { |
895 | struct audit_tty_status *s; |
896 | struct task_struct *tsk; |
897 | unsigned long flags; |
898 | |
899 | if (nlh->nlmsg_len < sizeof(struct audit_tty_status)) |
900 | return -EINVAL; |
901 | s = data; |
902 | if (s->enabled != 0 && s->enabled != 1) |
903 | return -EINVAL; |
904 | rcu_read_lock(); |
905 | tsk = find_task_by_vpid(pid); |
906 | if (tsk && lock_task_sighand(tsk, &flags)) { |
907 | tsk->signal->audit_tty = s->enabled != 0; |
908 | unlock_task_sighand(tsk, &flags); |
909 | } else |
910 | err = -ESRCH; |
911 | rcu_read_unlock(); |
912 | break; |
913 | } |
914 | default: |
915 | err = -EINVAL; |
916 | break; |
917 | } |
918 | |
919 | return err < 0 ? err : 0; |
920 | } |
921 | |
922 | /* |
923 | * Get message from skb. Each message is processed by audit_receive_msg. |
924 | * Malformed skbs with wrong length are discarded silently. |
925 | */ |
926 | static void audit_receive_skb(struct sk_buff *skb) |
927 | { |
928 | struct nlmsghdr *nlh; |
929 | /* |
930 | * len MUST be signed for NLMSG_NEXT to be able to dec it below 0 |
931 | * if the nlmsg_len was not aligned |
932 | */ |
933 | int len; |
934 | int err; |
935 | |
936 | nlh = nlmsg_hdr(skb); |
937 | len = skb->len; |
938 | |
939 | while (NLMSG_OK(nlh, len)) { |
940 | err = audit_receive_msg(skb, nlh); |
941 | /* if err or if this message says it wants a response */ |
942 | if (err || (nlh->nlmsg_flags & NLM_F_ACK)) |
943 | netlink_ack(skb, nlh, err); |
944 | |
945 | nlh = NLMSG_NEXT(nlh, len); |
946 | } |
947 | } |
948 | |
949 | /* Receive messages from netlink socket. */ |
950 | static void audit_receive(struct sk_buff *skb) |
951 | { |
952 | mutex_lock(&audit_cmd_mutex); |
953 | audit_receive_skb(skb); |
954 | mutex_unlock(&audit_cmd_mutex); |
955 | } |
956 | |
957 | /* Initialize audit support at boot time. */ |
958 | static int __init audit_init(void) |
959 | { |
960 | int i; |
961 | |
962 | if (audit_initialized == AUDIT_DISABLED) |
963 | return 0; |
964 | |
965 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", |
966 | audit_default ? "enabled" : "disabled"); |
967 | audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0, |
968 | audit_receive, NULL, THIS_MODULE); |
969 | if (!audit_sock) |
970 | audit_panic("cannot initialize netlink socket"); |
971 | else |
972 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; |
973 | |
974 | skb_queue_head_init(&audit_skb_queue); |
975 | skb_queue_head_init(&audit_skb_hold_queue); |
976 | audit_initialized = AUDIT_INITIALIZED; |
977 | audit_enabled = audit_default; |
978 | audit_ever_enabled |= !!audit_default; |
979 | |
980 | audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized"); |
981 | |
982 | for (i = 0; i < AUDIT_INODE_BUCKETS; i++) |
983 | INIT_LIST_HEAD(&audit_inode_hash[i]); |
984 | |
985 | return 0; |
986 | } |
987 | __initcall(audit_init); |
988 | |
989 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ |
990 | static int __init audit_enable(char *str) |
991 | { |
992 | audit_default = !!simple_strtol(str, NULL, 0); |
993 | if (!audit_default) |
994 | audit_initialized = AUDIT_DISABLED; |
995 | |
996 | printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled"); |
997 | |
998 | if (audit_initialized == AUDIT_INITIALIZED) { |
999 | audit_enabled = audit_default; |
1000 | audit_ever_enabled |= !!audit_default; |
1001 | } else if (audit_initialized == AUDIT_UNINITIALIZED) { |
1002 | printk(" (after initialization)"); |
1003 | } else { |
1004 | printk(" (until reboot)"); |
1005 | } |
1006 | printk("\n"); |
1007 | |
1008 | return 1; |
1009 | } |
1010 | |
1011 | __setup("audit=", audit_enable); |
1012 | |
1013 | static void audit_buffer_free(struct audit_buffer *ab) |
1014 | { |
1015 | unsigned long flags; |
1016 | |
1017 | if (!ab) |
1018 | return; |
1019 | |
1020 | if (ab->skb) |
1021 | kfree_skb(ab->skb); |
1022 | |
1023 | spin_lock_irqsave(&audit_freelist_lock, flags); |
1024 | if (audit_freelist_count > AUDIT_MAXFREE) |
1025 | kfree(ab); |
1026 | else { |
1027 | audit_freelist_count++; |
1028 | list_add(&ab->list, &audit_freelist); |
1029 | } |
1030 | spin_unlock_irqrestore(&audit_freelist_lock, flags); |
1031 | } |
1032 | |
1033 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
1034 | gfp_t gfp_mask, int type) |
1035 | { |
1036 | unsigned long flags; |
1037 | struct audit_buffer *ab = NULL; |
1038 | struct nlmsghdr *nlh; |
1039 | |
1040 | spin_lock_irqsave(&audit_freelist_lock, flags); |
1041 | if (!list_empty(&audit_freelist)) { |
1042 | ab = list_entry(audit_freelist.next, |
1043 | struct audit_buffer, list); |
1044 | list_del(&ab->list); |
1045 | --audit_freelist_count; |
1046 | } |
1047 | spin_unlock_irqrestore(&audit_freelist_lock, flags); |
1048 | |
1049 | if (!ab) { |
1050 | ab = kmalloc(sizeof(*ab), gfp_mask); |
1051 | if (!ab) |
1052 | goto err; |
1053 | } |
1054 | |
1055 | ab->ctx = ctx; |
1056 | ab->gfp_mask = gfp_mask; |
1057 | |
1058 | ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); |
1059 | if (!ab->skb) |
1060 | goto nlmsg_failure; |
1061 | |
1062 | nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0); |
1063 | |
1064 | return ab; |
1065 | |
1066 | nlmsg_failure: /* Used by NLMSG_NEW */ |
1067 | kfree_skb(ab->skb); |
1068 | ab->skb = NULL; |
1069 | err: |
1070 | audit_buffer_free(ab); |
1071 | return NULL; |
1072 | } |
1073 | |
1074 | /** |
1075 | * audit_serial - compute a serial number for the audit record |
1076 | * |
1077 | * Compute a serial number for the audit record. Audit records are |
1078 | * written to user-space as soon as they are generated, so a complete |
1079 | * audit record may be written in several pieces. The timestamp of the |
1080 | * record and this serial number are used by the user-space tools to |
1081 | * determine which pieces belong to the same audit record. The |
1082 | * (timestamp,serial) tuple is unique for each syscall and is live from |
1083 | * syscall entry to syscall exit. |
1084 | * |
1085 | * NOTE: Another possibility is to store the formatted records off the |
1086 | * audit context (for those records that have a context), and emit them |
1087 | * all at syscall exit. However, this could delay the reporting of |
1088 | * significant errors until syscall exit (or never, if the system |
1089 | * halts). |
1090 | */ |
1091 | unsigned int audit_serial(void) |
1092 | { |
1093 | static DEFINE_SPINLOCK(serial_lock); |
1094 | static unsigned int serial = 0; |
1095 | |
1096 | unsigned long flags; |
1097 | unsigned int ret; |
1098 | |
1099 | spin_lock_irqsave(&serial_lock, flags); |
1100 | do { |
1101 | ret = ++serial; |
1102 | } while (unlikely(!ret)); |
1103 | spin_unlock_irqrestore(&serial_lock, flags); |
1104 | |
1105 | return ret; |
1106 | } |
1107 | |
1108 | static inline void audit_get_stamp(struct audit_context *ctx, |
1109 | struct timespec *t, unsigned int *serial) |
1110 | { |
1111 | if (!ctx || !auditsc_get_stamp(ctx, t, serial)) { |
1112 | *t = CURRENT_TIME; |
1113 | *serial = audit_serial(); |
1114 | } |
1115 | } |
1116 | |
1117 | /* Obtain an audit buffer. This routine does locking to obtain the |
1118 | * audit buffer, but then no locking is required for calls to |
1119 | * audit_log_*format. If the tsk is a task that is currently in a |
1120 | * syscall, then the syscall is marked as auditable and an audit record |
1121 | * will be written at syscall exit. If there is no associated task, tsk |
1122 | * should be NULL. */ |
1123 | |
1124 | /** |
1125 | * audit_log_start - obtain an audit buffer |
1126 | * @ctx: audit_context (may be NULL) |
1127 | * @gfp_mask: type of allocation |
1128 | * @type: audit message type |
1129 | * |
1130 | * Returns audit_buffer pointer on success or NULL on error. |
1131 | * |
1132 | * Obtain an audit buffer. This routine does locking to obtain the |
1133 | * audit buffer, but then no locking is required for calls to |
1134 | * audit_log_*format. If the task (ctx) is a task that is currently in a |
1135 | * syscall, then the syscall is marked as auditable and an audit record |
1136 | * will be written at syscall exit. If there is no associated task, then |
1137 | * task context (ctx) should be NULL. |
1138 | */ |
1139 | struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, |
1140 | int type) |
1141 | { |
1142 | struct audit_buffer *ab = NULL; |
1143 | struct timespec t; |
1144 | unsigned int uninitialized_var(serial); |
1145 | int reserve; |
1146 | unsigned long timeout_start = jiffies; |
1147 | |
1148 | if (audit_initialized != AUDIT_INITIALIZED) |
1149 | return NULL; |
1150 | |
1151 | if (unlikely(audit_filter_type(type))) |
1152 | return NULL; |
1153 | |
1154 | if (gfp_mask & __GFP_WAIT) |
1155 | reserve = 0; |
1156 | else |
1157 | reserve = 5; /* Allow atomic callers to go up to five |
1158 | entries over the normal backlog limit */ |
1159 | |
1160 | while (audit_backlog_limit |
1161 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { |
1162 | if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time |
1163 | && time_before(jiffies, timeout_start + audit_backlog_wait_time)) { |
1164 | |
1165 | /* Wait for auditd to drain the queue a little */ |
1166 | DECLARE_WAITQUEUE(wait, current); |
1167 | set_current_state(TASK_INTERRUPTIBLE); |
1168 | add_wait_queue(&audit_backlog_wait, &wait); |
1169 | |
1170 | if (audit_backlog_limit && |
1171 | skb_queue_len(&audit_skb_queue) > audit_backlog_limit) |
1172 | schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies); |
1173 | |
1174 | __set_current_state(TASK_RUNNING); |
1175 | remove_wait_queue(&audit_backlog_wait, &wait); |
1176 | continue; |
1177 | } |
1178 | if (audit_rate_check() && printk_ratelimit()) |
1179 | printk(KERN_WARNING |
1180 | "audit: audit_backlog=%d > " |
1181 | "audit_backlog_limit=%d\n", |
1182 | skb_queue_len(&audit_skb_queue), |
1183 | audit_backlog_limit); |
1184 | audit_log_lost("backlog limit exceeded"); |
1185 | audit_backlog_wait_time = audit_backlog_wait_overflow; |
1186 | wake_up(&audit_backlog_wait); |
1187 | return NULL; |
1188 | } |
1189 | |
1190 | ab = audit_buffer_alloc(ctx, gfp_mask, type); |
1191 | if (!ab) { |
1192 | audit_log_lost("out of memory in audit_log_start"); |
1193 | return NULL; |
1194 | } |
1195 | |
1196 | audit_get_stamp(ab->ctx, &t, &serial); |
1197 | |
1198 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
1199 | t.tv_sec, t.tv_nsec/1000000, serial); |
1200 | return ab; |
1201 | } |
1202 | |
1203 | /** |
1204 | * audit_expand - expand skb in the audit buffer |
1205 | * @ab: audit_buffer |
1206 | * @extra: space to add at tail of the skb |
1207 | * |
1208 | * Returns 0 (no space) on failed expansion, or available space if |
1209 | * successful. |
1210 | */ |
1211 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
1212 | { |
1213 | struct sk_buff *skb = ab->skb; |
1214 | int oldtail = skb_tailroom(skb); |
1215 | int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask); |
1216 | int newtail = skb_tailroom(skb); |
1217 | |
1218 | if (ret < 0) { |
1219 | audit_log_lost("out of memory in audit_expand"); |
1220 | return 0; |
1221 | } |
1222 | |
1223 | skb->truesize += newtail - oldtail; |
1224 | return newtail; |
1225 | } |
1226 | |
1227 | /* |
1228 | * Format an audit message into the audit buffer. If there isn't enough |
1229 | * room in the audit buffer, more room will be allocated and vsnprint |
1230 | * will be called a second time. Currently, we assume that a printk |
1231 | * can't format message larger than 1024 bytes, so we don't either. |
1232 | */ |
1233 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, |
1234 | va_list args) |
1235 | { |
1236 | int len, avail; |
1237 | struct sk_buff *skb; |
1238 | va_list args2; |
1239 | |
1240 | if (!ab) |
1241 | return; |
1242 | |
1243 | BUG_ON(!ab->skb); |
1244 | skb = ab->skb; |
1245 | avail = skb_tailroom(skb); |
1246 | if (avail == 0) { |
1247 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
1248 | if (!avail) |
1249 | goto out; |
1250 | } |
1251 | va_copy(args2, args); |
1252 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args); |
1253 | if (len >= avail) { |
1254 | /* The printk buffer is 1024 bytes long, so if we get |
1255 | * here and AUDIT_BUFSIZ is at least 1024, then we can |
1256 | * log everything that printk could have logged. */ |
1257 | avail = audit_expand(ab, |
1258 | max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); |
1259 | if (!avail) |
1260 | goto out; |
1261 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); |
1262 | } |
1263 | va_end(args2); |
1264 | if (len > 0) |
1265 | skb_put(skb, len); |
1266 | out: |
1267 | return; |
1268 | } |
1269 | |
1270 | /** |
1271 | * audit_log_format - format a message into the audit buffer. |
1272 | * @ab: audit_buffer |
1273 | * @fmt: format string |
1274 | * @...: optional parameters matching @fmt string |
1275 | * |
1276 | * All the work is done in audit_log_vformat. |
1277 | */ |
1278 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) |
1279 | { |
1280 | va_list args; |
1281 | |
1282 | if (!ab) |
1283 | return; |
1284 | va_start(args, fmt); |
1285 | audit_log_vformat(ab, fmt, args); |
1286 | va_end(args); |
1287 | } |
1288 | |
1289 | /** |
1290 | * audit_log_hex - convert a buffer to hex and append it to the audit skb |
1291 | * @ab: the audit_buffer |
1292 | * @buf: buffer to convert to hex |
1293 | * @len: length of @buf to be converted |
1294 | * |
1295 | * No return value; failure to expand is silently ignored. |
1296 | * |
1297 | * This function will take the passed buf and convert it into a string of |
1298 | * ascii hex digits. The new string is placed onto the skb. |
1299 | */ |
1300 | void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, |
1301 | size_t len) |
1302 | { |
1303 | int i, avail, new_len; |
1304 | unsigned char *ptr; |
1305 | struct sk_buff *skb; |
1306 | static const unsigned char *hex = "0123456789ABCDEF"; |
1307 | |
1308 | if (!ab) |
1309 | return; |
1310 | |
1311 | BUG_ON(!ab->skb); |
1312 | skb = ab->skb; |
1313 | avail = skb_tailroom(skb); |
1314 | new_len = len<<1; |
1315 | if (new_len >= avail) { |
1316 | /* Round the buffer request up to the next multiple */ |
1317 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); |
1318 | avail = audit_expand(ab, new_len); |
1319 | if (!avail) |
1320 | return; |
1321 | } |
1322 | |
1323 | ptr = skb_tail_pointer(skb); |
1324 | for (i=0; i<len; i++) { |
1325 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ |
1326 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ |
1327 | } |
1328 | *ptr = 0; |
1329 | skb_put(skb, len << 1); /* new string is twice the old string */ |
1330 | } |
1331 | |
1332 | /* |
1333 | * Format a string of no more than slen characters into the audit buffer, |
1334 | * enclosed in quote marks. |
1335 | */ |
1336 | void audit_log_n_string(struct audit_buffer *ab, const char *string, |
1337 | size_t slen) |
1338 | { |
1339 | int avail, new_len; |
1340 | unsigned char *ptr; |
1341 | struct sk_buff *skb; |
1342 | |
1343 | if (!ab) |
1344 | return; |
1345 | |
1346 | BUG_ON(!ab->skb); |
1347 | skb = ab->skb; |
1348 | avail = skb_tailroom(skb); |
1349 | new_len = slen + 3; /* enclosing quotes + null terminator */ |
1350 | if (new_len > avail) { |
1351 | avail = audit_expand(ab, new_len); |
1352 | if (!avail) |
1353 | return; |
1354 | } |
1355 | ptr = skb_tail_pointer(skb); |
1356 | *ptr++ = '"'; |
1357 | memcpy(ptr, string, slen); |
1358 | ptr += slen; |
1359 | *ptr++ = '"'; |
1360 | *ptr = 0; |
1361 | skb_put(skb, slen + 2); /* don't include null terminator */ |
1362 | } |
1363 | |
1364 | /** |
1365 | * audit_string_contains_control - does a string need to be logged in hex |
1366 | * @string: string to be checked |
1367 | * @len: max length of the string to check |
1368 | */ |
1369 | int audit_string_contains_control(const char *string, size_t len) |
1370 | { |
1371 | const unsigned char *p; |
1372 | for (p = string; p < (const unsigned char *)string + len; p++) { |
1373 | if (*p == '"' || *p < 0x21 || *p > 0x7e) |
1374 | return 1; |
1375 | } |
1376 | return 0; |
1377 | } |
1378 | |
1379 | /** |
1380 | * audit_log_n_untrustedstring - log a string that may contain random characters |
1381 | * @ab: audit_buffer |
1382 | * @len: length of string (not including trailing null) |
1383 | * @string: string to be logged |
1384 | * |
1385 | * This code will escape a string that is passed to it if the string |
1386 | * contains a control character, unprintable character, double quote mark, |
1387 | * or a space. Unescaped strings will start and end with a double quote mark. |
1388 | * Strings that are escaped are printed in hex (2 digits per char). |
1389 | * |
1390 | * The caller specifies the number of characters in the string to log, which may |
1391 | * or may not be the entire string. |
1392 | */ |
1393 | void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string, |
1394 | size_t len) |
1395 | { |
1396 | if (audit_string_contains_control(string, len)) |
1397 | audit_log_n_hex(ab, string, len); |
1398 | else |
1399 | audit_log_n_string(ab, string, len); |
1400 | } |
1401 | |
1402 | /** |
1403 | * audit_log_untrustedstring - log a string that may contain random characters |
1404 | * @ab: audit_buffer |
1405 | * @string: string to be logged |
1406 | * |
1407 | * Same as audit_log_n_untrustedstring(), except that strlen is used to |
1408 | * determine string length. |
1409 | */ |
1410 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) |
1411 | { |
1412 | audit_log_n_untrustedstring(ab, string, strlen(string)); |
1413 | } |
1414 | |
1415 | /* This is a helper-function to print the escaped d_path */ |
1416 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, |
1417 | struct path *path) |
1418 | { |
1419 | char *p, *pathname; |
1420 | |
1421 | if (prefix) |
1422 | audit_log_format(ab, " %s", prefix); |
1423 | |
1424 | /* We will allow 11 spaces for ' (deleted)' to be appended */ |
1425 | pathname = kmalloc(PATH_MAX+11, ab->gfp_mask); |
1426 | if (!pathname) { |
1427 | audit_log_string(ab, "<no_memory>"); |
1428 | return; |
1429 | } |
1430 | p = d_path(path, pathname, PATH_MAX+11); |
1431 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ |
1432 | /* FIXME: can we save some information here? */ |
1433 | audit_log_string(ab, "<too_long>"); |
1434 | } else |
1435 | audit_log_untrustedstring(ab, p); |
1436 | kfree(pathname); |
1437 | } |
1438 | |
1439 | void audit_log_key(struct audit_buffer *ab, char *key) |
1440 | { |
1441 | audit_log_format(ab, " key="); |
1442 | if (key) |
1443 | audit_log_untrustedstring(ab, key); |
1444 | else |
1445 | audit_log_format(ab, "(null)"); |
1446 | } |
1447 | |
1448 | /** |
1449 | * audit_log_end - end one audit record |
1450 | * @ab: the audit_buffer |
1451 | * |
1452 | * The netlink_* functions cannot be called inside an irq context, so |
1453 | * the audit buffer is placed on a queue and a tasklet is scheduled to |
1454 | * remove them from the queue outside the irq context. May be called in |
1455 | * any context. |
1456 | */ |
1457 | void audit_log_end(struct audit_buffer *ab) |
1458 | { |
1459 | if (!ab) |
1460 | return; |
1461 | if (!audit_rate_check()) { |
1462 | audit_log_lost("rate limit exceeded"); |
1463 | } else { |
1464 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); |
1465 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); |
1466 | |
1467 | if (audit_pid) { |
1468 | skb_queue_tail(&audit_skb_queue, ab->skb); |
1469 | wake_up_interruptible(&kauditd_wait); |
1470 | } else { |
1471 | audit_printk_skb(ab->skb); |
1472 | } |
1473 | ab->skb = NULL; |
1474 | } |
1475 | audit_buffer_free(ab); |
1476 | } |
1477 | |
1478 | /** |
1479 | * audit_log - Log an audit record |
1480 | * @ctx: audit context |
1481 | * @gfp_mask: type of allocation |
1482 | * @type: audit message type |
1483 | * @fmt: format string to use |
1484 | * @...: variable parameters matching the format string |
1485 | * |
1486 | * This is a convenience function that calls audit_log_start, |
1487 | * audit_log_vformat, and audit_log_end. It may be called |
1488 | * in any context. |
1489 | */ |
1490 | void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, |
1491 | const char *fmt, ...) |
1492 | { |
1493 | struct audit_buffer *ab; |
1494 | va_list args; |
1495 | |
1496 | ab = audit_log_start(ctx, gfp_mask, type); |
1497 | if (ab) { |
1498 | va_start(args, fmt); |
1499 | audit_log_vformat(ab, fmt, args); |
1500 | va_end(args); |
1501 | audit_log_end(ab); |
1502 | } |
1503 | } |
1504 | |
1505 | EXPORT_SYMBOL(audit_log_start); |
1506 | EXPORT_SYMBOL(audit_log_end); |
1507 | EXPORT_SYMBOL(audit_log_format); |
1508 | EXPORT_SYMBOL(audit_log); |
1509 |
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