projects/linux·blob v2.6.16 · refs

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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 2003-2004 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 <[email protected]>
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 *
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/err.h>
50#include <linux/kthread.h>
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.) */
60static int audit_initialized;
61
62/* No syscall auditing will take place unless audit_enabled != 0. */
63int audit_enabled;
64
65/* Default state when kernel boots without any parameters. */
66static int audit_default;
67
68/* If auditing cannot proceed, audit_failure selects what happens. */
69static 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. */
73int audit_pid;
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. */
78static int audit_rate_limit;
79
80/* Number of outstanding audit_buffers allowed. */
81static int audit_backlog_limit = 64;
82static int audit_backlog_wait_time = 60 * HZ;
83static int audit_backlog_wait_overflow = 0;
84
85/* The identity of the user shutting down the audit system. */
86uid_t audit_sig_uid = -1;
87pid_t audit_sig_pid = -1;
88
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*/
96static atomic_t audit_lost = ATOMIC_INIT(0);
97
98/* The netlink socket. */
99static struct sock *audit_sock;
100
101/* The audit_freelist is a list of pre-allocated audit buffers (if more
102 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
103 * being placed on the freelist). */
104static DEFINE_SPINLOCK(audit_freelist_lock);
105static int audit_freelist_count = 0;
106static LIST_HEAD(audit_freelist);
107
108static struct sk_buff_head audit_skb_queue;
109static struct task_struct *kauditd_task;
110static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
111static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
112
113/* The netlink socket is only to be read by 1 CPU, which lets us assume
114 * that list additions and deletions never happen simultaneously in
115 * auditsc.c */
116DECLARE_MUTEX(audit_netlink_sem);
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. */
132struct audit_buffer {
133 struct list_head list;
134 struct sk_buff *skb; /* formatted skb ready to send */
135 struct audit_context *ctx; /* NULL or associated context */
136 gfp_t gfp_mask;
137};
138
139static 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
145static void audit_panic(const char *message)
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
160static 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
189/* Emit at least 1 message per second, even if audit_rate_check is
190 * throttling. */
191void audit_log_lost(const char *message)
192{
193 static unsigned long last_msg = 0;
194 static DEFINE_SPINLOCK(lock);
195 unsigned long flags;
196 unsigned long now;
197 int print;
198
199 atomic_inc(&audit_lost);
200
201 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
202
203 if (!print) {
204 spin_lock_irqsave(&lock, flags);
205 now = jiffies;
206 if (now - last_msg > HZ) {
207 print = 1;
208 last_msg = now;
209 }
210 spin_unlock_irqrestore(&lock, flags);
211 }
212
213 if (print) {
214 printk(KERN_WARNING
215 "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n",
216 atomic_read(&audit_lost),
217 audit_rate_limit,
218 audit_backlog_limit);
219 audit_panic(message);
220 }
221
222}
223
224static int audit_set_rate_limit(int limit, uid_t loginuid)
225{
226 int old = audit_rate_limit;
227 audit_rate_limit = limit;
228 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
229 "audit_rate_limit=%d old=%d by auid=%u",
230 audit_rate_limit, old, loginuid);
231 return old;
232}
233
234static int audit_set_backlog_limit(int limit, uid_t loginuid)
235{
236 int old = audit_backlog_limit;
237 audit_backlog_limit = limit;
238 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
239 "audit_backlog_limit=%d old=%d by auid=%u",
240 audit_backlog_limit, old, loginuid);
241 return old;
242}
243
244static int audit_set_enabled(int state, uid_t loginuid)
245{
246 int old = audit_enabled;
247 if (state != 0 && state != 1)
248 return -EINVAL;
249 audit_enabled = state;
250 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
251 "audit_enabled=%d old=%d by auid=%u",
252 audit_enabled, old, loginuid);
253 return old;
254}
255
256static int audit_set_failure(int state, uid_t loginuid)
257{
258 int old = audit_failure;
259 if (state != AUDIT_FAIL_SILENT
260 && state != AUDIT_FAIL_PRINTK
261 && state != AUDIT_FAIL_PANIC)
262 return -EINVAL;
263 audit_failure = state;
264 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
265 "audit_failure=%d old=%d by auid=%u",
266 audit_failure, old, loginuid);
267 return old;
268}
269
270static int kauditd_thread(void *dummy)
271{
272 struct sk_buff *skb;
273
274 while (1) {
275 skb = skb_dequeue(&audit_skb_queue);
276 wake_up(&audit_backlog_wait);
277 if (skb) {
278 if (audit_pid) {
279 int err = netlink_unicast(audit_sock, skb, audit_pid, 0);
280 if (err < 0) {
281 BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
282 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
283 audit_pid = 0;
284 }
285 } else {
286 printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0));
287 kfree_skb(skb);
288 }
289 } else {
290 DECLARE_WAITQUEUE(wait, current);
291 set_current_state(TASK_INTERRUPTIBLE);
292 add_wait_queue(&kauditd_wait, &wait);
293
294 if (!skb_queue_len(&audit_skb_queue)) {
295 try_to_freeze();
296 schedule();
297 }
298
299 __set_current_state(TASK_RUNNING);
300 remove_wait_queue(&kauditd_wait, &wait);
301 }
302 }
303}
304
305void audit_send_reply(int pid, int seq, int type, int done, int multi,
306 void *payload, int size)
307{
308 struct sk_buff *skb;
309 struct nlmsghdr *nlh;
310 int len = NLMSG_SPACE(size);
311 void *data;
312 int flags = multi ? NLM_F_MULTI : 0;
313 int t = done ? NLMSG_DONE : type;
314
315 skb = alloc_skb(len, GFP_KERNEL);
316 if (!skb)
317 return;
318
319 nlh = NLMSG_PUT(skb, pid, seq, t, size);
320 nlh->nlmsg_flags = flags;
321 data = NLMSG_DATA(nlh);
322 memcpy(data, payload, size);
323
324 /* Ignore failure. It'll only happen if the sender goes away,
325 because our timeout is set to infinite. */
326 netlink_unicast(audit_sock, skb, pid, 0);
327 return;
328
329nlmsg_failure: /* Used by NLMSG_PUT */
330 if (skb)
331 kfree_skb(skb);
332}
333
334/*
335 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
336 * control messages.
337 */
338static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type)
339{
340 int err = 0;
341
342 switch (msg_type) {
343 case AUDIT_GET:
344 case AUDIT_LIST:
345 case AUDIT_SET:
346 case AUDIT_ADD:
347 case AUDIT_DEL:
348 case AUDIT_SIGNAL_INFO:
349 if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL))
350 err = -EPERM;
351 break;
352 case AUDIT_USER:
353 case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
354 if (!cap_raised(eff_cap, CAP_AUDIT_WRITE))
355 err = -EPERM;
356 break;
357 default: /* bad msg */
358 err = -EINVAL;
359 }
360
361 return err;
362}
363
364static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
365{
366 u32 uid, pid, seq;
367 void *data;
368 struct audit_status *status_get, status_set;
369 int err;
370 struct audit_buffer *ab;
371 u16 msg_type = nlh->nlmsg_type;
372 uid_t loginuid; /* loginuid of sender */
373 struct audit_sig_info sig_data;
374
375 err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type);
376 if (err)
377 return err;
378
379 /* As soon as there's any sign of userspace auditd, start kauditd to talk to it */
380 if (!kauditd_task)
381 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
382 if (IS_ERR(kauditd_task)) {
383 err = PTR_ERR(kauditd_task);
384 kauditd_task = NULL;
385 return err;
386 }
387
388 pid = NETLINK_CREDS(skb)->pid;
389 uid = NETLINK_CREDS(skb)->uid;
390 loginuid = NETLINK_CB(skb).loginuid;
391 seq = nlh->nlmsg_seq;
392 data = NLMSG_DATA(nlh);
393
394 switch (msg_type) {
395 case AUDIT_GET:
396 status_set.enabled = audit_enabled;
397 status_set.failure = audit_failure;
398 status_set.pid = audit_pid;
399 status_set.rate_limit = audit_rate_limit;
400 status_set.backlog_limit = audit_backlog_limit;
401 status_set.lost = atomic_read(&audit_lost);
402 status_set.backlog = skb_queue_len(&audit_skb_queue);
403 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
404 &status_set, sizeof(status_set));
405 break;
406 case AUDIT_SET:
407 if (nlh->nlmsg_len < sizeof(struct audit_status))
408 return -EINVAL;
409 status_get = (struct audit_status *)data;
410 if (status_get->mask & AUDIT_STATUS_ENABLED) {
411 err = audit_set_enabled(status_get->enabled, loginuid);
412 if (err < 0) return err;
413 }
414 if (status_get->mask & AUDIT_STATUS_FAILURE) {
415 err = audit_set_failure(status_get->failure, loginuid);
416 if (err < 0) return err;
417 }
418 if (status_get->mask & AUDIT_STATUS_PID) {
419 int old = audit_pid;
420 audit_pid = status_get->pid;
421 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
422 "audit_pid=%d old=%d by auid=%u",
423 audit_pid, old, loginuid);
424 }
425 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
426 audit_set_rate_limit(status_get->rate_limit, loginuid);
427 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
428 audit_set_backlog_limit(status_get->backlog_limit,
429 loginuid);
430 break;
431 case AUDIT_USER:
432 case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
433 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
434 return 0;
435
436 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
437 if (err == 1) {
438 err = 0;
439 ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
440 if (ab) {
441 audit_log_format(ab,
442 "user pid=%d uid=%u auid=%u msg='%.1024s'",
443 pid, uid, loginuid, (char *)data);
444 audit_set_pid(ab, pid);
445 audit_log_end(ab);
446 }
447 }
448 break;
449 case AUDIT_ADD:
450 case AUDIT_DEL:
451 if (nlh->nlmsg_len < sizeof(struct audit_rule))
452 return -EINVAL;
453 /* fallthrough */
454 case AUDIT_LIST:
455 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
456 uid, seq, data, loginuid);
457 break;
458 case AUDIT_SIGNAL_INFO:
459 sig_data.uid = audit_sig_uid;
460 sig_data.pid = audit_sig_pid;
461 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
462 0, 0, &sig_data, sizeof(sig_data));
463 break;
464 default:
465 err = -EINVAL;
466 break;
467 }
468
469 return err < 0 ? err : 0;
470}
471
472/* Get message from skb (based on rtnetlink_rcv_skb). Each message is
473 * processed by audit_receive_msg. Malformed skbs with wrong length are
474 * discarded silently. */
475static void audit_receive_skb(struct sk_buff *skb)
476{
477 int err;
478 struct nlmsghdr *nlh;
479 u32 rlen;
480
481 while (skb->len >= NLMSG_SPACE(0)) {
482 nlh = (struct nlmsghdr *)skb->data;
483 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
484 return;
485 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
486 if (rlen > skb->len)
487 rlen = skb->len;
488 if ((err = audit_receive_msg(skb, nlh))) {
489 netlink_ack(skb, nlh, err);
490 } else if (nlh->nlmsg_flags & NLM_F_ACK)
491 netlink_ack(skb, nlh, 0);
492 skb_pull(skb, rlen);
493 }
494}
495
496/* Receive messages from netlink socket. */
497static void audit_receive(struct sock *sk, int length)
498{
499 struct sk_buff *skb;
500 unsigned int qlen;
501
502 down(&audit_netlink_sem);
503
504 for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) {
505 skb = skb_dequeue(&sk->sk_receive_queue);
506 audit_receive_skb(skb);
507 kfree_skb(skb);
508 }
509 up(&audit_netlink_sem);
510}
511
512
513/* Initialize audit support at boot time. */
514static int __init audit_init(void)
515{
516 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
517 audit_default ? "enabled" : "disabled");
518 audit_sock = netlink_kernel_create(NETLINK_AUDIT, 0, audit_receive,
519 THIS_MODULE);
520 if (!audit_sock)
521 audit_panic("cannot initialize netlink socket");
522
523 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
524 skb_queue_head_init(&audit_skb_queue);
525 audit_initialized = 1;
526 audit_enabled = audit_default;
527 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
528 return 0;
529}
530__initcall(audit_init);
531
532/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
533static int __init audit_enable(char *str)
534{
535 audit_default = !!simple_strtol(str, NULL, 0);
536 printk(KERN_INFO "audit: %s%s\n",
537 audit_default ? "enabled" : "disabled",
538 audit_initialized ? "" : " (after initialization)");
539 if (audit_initialized)
540 audit_enabled = audit_default;
541 return 0;
542}
543
544__setup("audit=", audit_enable);
545
546static void audit_buffer_free(struct audit_buffer *ab)
547{
548 unsigned long flags;
549
550 if (!ab)
551 return;
552
553 if (ab->skb)
554 kfree_skb(ab->skb);
555
556 spin_lock_irqsave(&audit_freelist_lock, flags);
557 if (++audit_freelist_count > AUDIT_MAXFREE)
558 kfree(ab);
559 else
560 list_add(&ab->list, &audit_freelist);
561 spin_unlock_irqrestore(&audit_freelist_lock, flags);
562}
563
564static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
565 gfp_t gfp_mask, int type)
566{
567 unsigned long flags;
568 struct audit_buffer *ab = NULL;
569 struct nlmsghdr *nlh;
570
571 spin_lock_irqsave(&audit_freelist_lock, flags);
572 if (!list_empty(&audit_freelist)) {
573 ab = list_entry(audit_freelist.next,
574 struct audit_buffer, list);
575 list_del(&ab->list);
576 --audit_freelist_count;
577 }
578 spin_unlock_irqrestore(&audit_freelist_lock, flags);
579
580 if (!ab) {
581 ab = kmalloc(sizeof(*ab), gfp_mask);
582 if (!ab)
583 goto err;
584 }
585
586 ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
587 if (!ab->skb)
588 goto err;
589
590 ab->ctx = ctx;
591 ab->gfp_mask = gfp_mask;
592 nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
593 nlh->nlmsg_type = type;
594 nlh->nlmsg_flags = 0;
595 nlh->nlmsg_pid = 0;
596 nlh->nlmsg_seq = 0;
597 return ab;
598err:
599 audit_buffer_free(ab);
600 return NULL;
601}
602
603/* Compute a serial number for the audit record. Audit records are
604 * written to user-space as soon as they are generated, so a complete
605 * audit record may be written in several pieces. The timestamp of the
606 * record and this serial number are used by the user-space tools to
607 * determine which pieces belong to the same audit record. The
608 * (timestamp,serial) tuple is unique for each syscall and is live from
609 * syscall entry to syscall exit.
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
617unsigned int audit_serial(void)
618{
619 static spinlock_t serial_lock = SPIN_LOCK_UNLOCKED;
620 static unsigned int serial = 0;
621
622 unsigned long flags;
623 unsigned int ret;
624
625 spin_lock_irqsave(&serial_lock, flags);
626 do {
627 ret = ++serial;
628 } while (unlikely(!ret));
629 spin_unlock_irqrestore(&serial_lock, flags);
630
631 return ret;
632}
633
634static inline void audit_get_stamp(struct audit_context *ctx,
635 struct timespec *t, unsigned int *serial)
636{
637 if (ctx)
638 auditsc_get_stamp(ctx, t, serial);
639 else {
640 *t = CURRENT_TIME;
641 *serial = audit_serial();
642 }
643}
644
645/* Obtain an audit buffer. This routine does locking to obtain the
646 * audit buffer, but then no locking is required for calls to
647 * audit_log_*format. If the tsk is a task that is currently in a
648 * syscall, then the syscall is marked as auditable and an audit record
649 * will be written at syscall exit. If there is no associated task, tsk
650 * should be NULL. */
651
652struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
653 int type)
654{
655 struct audit_buffer *ab = NULL;
656 struct timespec t;
657 unsigned int serial;
658 int reserve;
659 unsigned long timeout_start = jiffies;
660
661 if (!audit_initialized)
662 return NULL;
663
664 if (gfp_mask & __GFP_WAIT)
665 reserve = 0;
666 else
667 reserve = 5; /* Allow atomic callers to go up to five
668 entries over the normal backlog limit */
669
670 while (audit_backlog_limit
671 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
672 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
673 && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
674
675 /* Wait for auditd to drain the queue a little */
676 DECLARE_WAITQUEUE(wait, current);
677 set_current_state(TASK_INTERRUPTIBLE);
678 add_wait_queue(&audit_backlog_wait, &wait);
679
680 if (audit_backlog_limit &&
681 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
682 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
683
684 __set_current_state(TASK_RUNNING);
685 remove_wait_queue(&audit_backlog_wait, &wait);
686 continue;
687 }
688 if (audit_rate_check())
689 printk(KERN_WARNING
690 "audit: audit_backlog=%d > "
691 "audit_backlog_limit=%d\n",
692 skb_queue_len(&audit_skb_queue),
693 audit_backlog_limit);
694 audit_log_lost("backlog limit exceeded");
695 audit_backlog_wait_time = audit_backlog_wait_overflow;
696 wake_up(&audit_backlog_wait);
697 return NULL;
698 }
699
700 ab = audit_buffer_alloc(ctx, gfp_mask, type);
701 if (!ab) {
702 audit_log_lost("out of memory in audit_log_start");
703 return NULL;
704 }
705
706 audit_get_stamp(ab->ctx, &t, &serial);
707
708 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
709 t.tv_sec, t.tv_nsec/1000000, serial);
710 return ab;
711}
712
713/**
714 * audit_expand - expand skb in the audit buffer
715 * @ab: audit_buffer
716 *
717 * Returns 0 (no space) on failed expansion, or available space if
718 * successful.
719 */
720static inline int audit_expand(struct audit_buffer *ab, int extra)
721{
722 struct sk_buff *skb = ab->skb;
723 int ret = pskb_expand_head(skb, skb_headroom(skb), extra,
724 ab->gfp_mask);
725 if (ret < 0) {
726 audit_log_lost("out of memory in audit_expand");
727 return 0;
728 }
729 return skb_tailroom(skb);
730}
731
732/* Format an audit message into the audit buffer. If there isn't enough
733 * room in the audit buffer, more room will be allocated and vsnprint
734 * will be called a second time. Currently, we assume that a printk
735 * can't format message larger than 1024 bytes, so we don't either. */
736static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
737 va_list args)
738{
739 int len, avail;
740 struct sk_buff *skb;
741 va_list args2;
742
743 if (!ab)
744 return;
745
746 BUG_ON(!ab->skb);
747 skb = ab->skb;
748 avail = skb_tailroom(skb);
749 if (avail == 0) {
750 avail = audit_expand(ab, AUDIT_BUFSIZ);
751 if (!avail)
752 goto out;
753 }
754 va_copy(args2, args);
755 len = vsnprintf(skb->tail, avail, fmt, args);
756 if (len >= avail) {
757 /* The printk buffer is 1024 bytes long, so if we get
758 * here and AUDIT_BUFSIZ is at least 1024, then we can
759 * log everything that printk could have logged. */
760 avail = audit_expand(ab, max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
761 if (!avail)
762 goto out;
763 len = vsnprintf(skb->tail, avail, fmt, args2);
764 }
765 if (len > 0)
766 skb_put(skb, len);
767out:
768 return;
769}
770
771/* Format a message into the audit buffer. All the work is done in
772 * audit_log_vformat. */
773void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
774{
775 va_list args;
776
777 if (!ab)
778 return;
779 va_start(args, fmt);
780 audit_log_vformat(ab, fmt, args);
781 va_end(args);
782}
783
784/* This function will take the passed buf and convert it into a string of
785 * ascii hex digits. The new string is placed onto the skb. */
786void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
787 size_t len)
788{
789 int i, avail, new_len;
790 unsigned char *ptr;
791 struct sk_buff *skb;
792 static const unsigned char *hex = "0123456789ABCDEF";
793
794 BUG_ON(!ab->skb);
795 skb = ab->skb;
796 avail = skb_tailroom(skb);
797 new_len = len<<1;
798 if (new_len >= avail) {
799 /* Round the buffer request up to the next multiple */
800 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
801 avail = audit_expand(ab, new_len);
802 if (!avail)
803 return;
804 }
805
806 ptr = skb->tail;
807 for (i=0; i<len; i++) {
808 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
809 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
810 }
811 *ptr = 0;
812 skb_put(skb, len << 1); /* new string is twice the old string */
813}
814
815/* This code will escape a string that is passed to it if the string
816 * contains a control character, unprintable character, double quote mark,
817 * or a space. Unescaped strings will start and end with a double quote mark.
818 * Strings that are escaped are printed in hex (2 digits per char). */
819void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
820{
821 const unsigned char *p = string;
822
823 while (*p) {
824 if (*p == '"' || *p < 0x21 || *p > 0x7f) {
825 audit_log_hex(ab, string, strlen(string));
826 return;
827 }
828 p++;
829 }
830 audit_log_format(ab, "\"%s\"", string);
831}
832
833/* This is a helper-function to print the escaped d_path */
834void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
835 struct dentry *dentry, struct vfsmount *vfsmnt)
836{
837 char *p, *path;
838
839 if (prefix)
840 audit_log_format(ab, " %s", prefix);
841
842 /* We will allow 11 spaces for ' (deleted)' to be appended */
843 path = kmalloc(PATH_MAX+11, ab->gfp_mask);
844 if (!path) {
845 audit_log_format(ab, "<no memory>");
846 return;
847 }
848 p = d_path(dentry, vfsmnt, path, PATH_MAX+11);
849 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
850 /* FIXME: can we save some information here? */
851 audit_log_format(ab, "<too long>");
852 } else
853 audit_log_untrustedstring(ab, p);
854 kfree(path);
855}
856
857/* The netlink_* functions cannot be called inside an irq context, so
858 * the audit buffer is places on a queue and a tasklet is scheduled to
859 * remove them from the queue outside the irq context. May be called in
860 * any context. */
861void audit_log_end(struct audit_buffer *ab)
862{
863 if (!ab)
864 return;
865 if (!audit_rate_check()) {
866 audit_log_lost("rate limit exceeded");
867 } else {
868 if (audit_pid) {
869 struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
870 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
871 skb_queue_tail(&audit_skb_queue, ab->skb);
872 ab->skb = NULL;
873 wake_up_interruptible(&kauditd_wait);
874 } else {
875 printk(KERN_NOTICE "%s\n", ab->skb->data + NLMSG_SPACE(0));
876 }
877 }
878 audit_buffer_free(ab);
879}
880
881/* Log an audit record. This is a convenience function that calls
882 * audit_log_start, audit_log_vformat, and audit_log_end. It may be
883 * called in any context. */
884void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
885 const char *fmt, ...)
886{
887 struct audit_buffer *ab;
888 va_list args;
889
890 ab = audit_log_start(ctx, gfp_mask, type);
891 if (ab) {
892 va_start(args, fmt);
893 audit_log_vformat(ab, fmt, args);
894 va_end(args);
895 audit_log_end(ab);
896 }
897}