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diff --git a/kernel/audit.c b/kernel/audit.c
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1/* audit.c -- Auditing support -*- linux-c -*-
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 *
41 * Example user-space utilities: http://people.redhat.com/faith/audit/
42 */
43
44#include <linux/init.h>
45#include <asm/atomic.h>
46#include <asm/types.h>
47#include <linux/mm.h>
48#include <linux/module.h>
49
50#include <linux/audit.h>
51
52#include <net/sock.h>
53#include <linux/skbuff.h>
54#include <linux/netlink.h>
55
56/* No auditing will take place until audit_initialized != 0.
57 * (Initialization happens after skb_init is called.) */
58static int audit_initialized;
59
60/* No syscall auditing will take place unless audit_enabled != 0. */
61int audit_enabled;
62
63/* Default state when kernel boots without any parameters. */
64static int audit_default;
65
66/* If auditing cannot proceed, audit_failure selects what happens. */
67static int audit_failure = AUDIT_FAIL_PRINTK;
68
69/* If audit records are to be written to the netlink socket, audit_pid
70 * contains the (non-zero) pid. */
71static int audit_pid;
72
73/* If audit_limit is non-zero, limit the rate of sending audit records
74 * to that number per second. This prevents DoS attacks, but results in
75 * audit records being dropped. */
76static int audit_rate_limit;
77
78/* Number of outstanding audit_buffers allowed. */
79static int audit_backlog_limit = 64;
80static atomic_t audit_backlog = ATOMIC_INIT(0);
81
82/* Records can be lost in several ways:
83 0) [suppressed in audit_alloc]
84 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
85 2) out of memory in audit_log_move [alloc_skb]
86 3) suppressed due to audit_rate_limit
87 4) suppressed due to audit_backlog_limit
88*/
89static atomic_t audit_lost = ATOMIC_INIT(0);
90
91/* The netlink socket. */
92static struct sock *audit_sock;
93
94/* There are two lists of audit buffers. The txlist contains audit
95 * buffers that cannot be sent immediately to the netlink device because
96 * we are in an irq context (these are sent later in a tasklet).
97 *
98 * The second list is a list of pre-allocated audit buffers (if more
99 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
100 * being placed on the freelist). */
101static DEFINE_SPINLOCK(audit_txlist_lock);
102static DEFINE_SPINLOCK(audit_freelist_lock);
103static int audit_freelist_count = 0;
104static LIST_HEAD(audit_txlist);
105static LIST_HEAD(audit_freelist);
106
107/* There are three lists of rules -- one to search at task creation
108 * time, one to search at syscall entry time, and another to search at
109 * syscall exit time. */
110static LIST_HEAD(audit_tsklist);
111static LIST_HEAD(audit_entlist);
112static LIST_HEAD(audit_extlist);
113
114/* The netlink socket is only to be read by 1 CPU, which lets us assume
115 * that list additions and deletions never happen simultaneiously in
116 * auditsc.c */
117static DECLARE_MUTEX(audit_netlink_sem);
118
119/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
120 * audit records. Since printk uses a 1024 byte buffer, this buffer
121 * should be at least that large. */
122#define AUDIT_BUFSIZ 1024
123
124/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
125 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
126#define AUDIT_MAXFREE (2*NR_CPUS)
127
128/* The audit_buffer is used when formatting an audit record. The caller
129 * locks briefly to get the record off the freelist or to allocate the
130 * buffer, and locks briefly to send the buffer to the netlink layer or
131 * to place it on a transmit queue. Multiple audit_buffers can be in
132 * use simultaneously. */
133struct audit_buffer {
134 struct list_head list;
135 struct sk_buff_head sklist; /* formatted skbs ready to send */
136 struct audit_context *ctx; /* NULL or associated context */
137 int len; /* used area of tmp */
138 char tmp[AUDIT_BUFSIZ];
139
140 /* Pointer to header and contents */
141 struct nlmsghdr *nlh;
142 int total;
143 int type;
144 int pid;
145 int count; /* Times requeued */
146};
147
148void audit_set_type(struct audit_buffer *ab, int type)
149{
150 ab->type = type;
151}
152
153struct audit_entry {
154 struct list_head list;
155 struct audit_rule rule;
156};
157
158static void audit_log_end_irq(struct audit_buffer *ab);
159static void audit_log_end_fast(struct audit_buffer *ab);
160
161static void audit_panic(const char *message)
162{
163 switch (audit_failure)
164 {
165 case AUDIT_FAIL_SILENT:
166 break;
167 case AUDIT_FAIL_PRINTK:
168 printk(KERN_ERR "audit: %s\n", message);
169 break;
170 case AUDIT_FAIL_PANIC:
171 panic("audit: %s\n", message);
172 break;
173 }
174}
175
176static inline int audit_rate_check(void)
177{
178 static unsigned long last_check = 0;
179 static int messages = 0;
180 static DEFINE_SPINLOCK(lock);
181 unsigned long flags;
182 unsigned long now;
183 unsigned long elapsed;
184 int retval = 0;
185
186 if (!audit_rate_limit) return 1;
187
188 spin_lock_irqsave(&lock, flags);
189 if (++messages < audit_rate_limit) {
190 retval = 1;
191 } else {
192 now = jiffies;
193 elapsed = now - last_check;
194 if (elapsed > HZ) {
195 last_check = now;
196 messages = 0;
197 retval = 1;
198 }
199 }
200 spin_unlock_irqrestore(&lock, flags);
201
202 return retval;
203}
204
205/* Emit at least 1 message per second, even if audit_rate_check is
206 * throttling. */
207void audit_log_lost(const char *message)
208{
209 static unsigned long last_msg = 0;
210 static DEFINE_SPINLOCK(lock);
211 unsigned long flags;
212 unsigned long now;
213 int print;
214
215 atomic_inc(&audit_lost);
216
217 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
218
219 if (!print) {
220 spin_lock_irqsave(&lock, flags);
221 now = jiffies;
222 if (now - last_msg > HZ) {
223 print = 1;
224 last_msg = now;
225 }
226 spin_unlock_irqrestore(&lock, flags);
227 }
228
229 if (print) {
230 printk(KERN_WARNING
231 "audit: audit_lost=%d audit_backlog=%d"
232 " audit_rate_limit=%d audit_backlog_limit=%d\n",
233 atomic_read(&audit_lost),
234 atomic_read(&audit_backlog),
235 audit_rate_limit,
236 audit_backlog_limit);
237 audit_panic(message);
238 }
239
240}
241
242static int audit_set_rate_limit(int limit)
243{
244 int old = audit_rate_limit;
245 audit_rate_limit = limit;
246 audit_log(current->audit_context, "audit_rate_limit=%d old=%d",
247 audit_rate_limit, old);
248 return old;
249}
250
251static int audit_set_backlog_limit(int limit)
252{
253 int old = audit_backlog_limit;
254 audit_backlog_limit = limit;
255 audit_log(current->audit_context, "audit_backlog_limit=%d old=%d",
256 audit_backlog_limit, old);
257 return old;
258}
259
260static int audit_set_enabled(int state)
261{
262 int old = audit_enabled;
263 if (state != 0 && state != 1)
264 return -EINVAL;
265 audit_enabled = state;
266 audit_log(current->audit_context, "audit_enabled=%d old=%d",
267 audit_enabled, old);
268 return old;
269}
270
271static int audit_set_failure(int state)
272{
273 int old = audit_failure;
274 if (state != AUDIT_FAIL_SILENT
275 && state != AUDIT_FAIL_PRINTK
276 && state != AUDIT_FAIL_PANIC)
277 return -EINVAL;
278 audit_failure = state;
279 audit_log(current->audit_context, "audit_failure=%d old=%d",
280 audit_failure, old);
281 return old;
282}
283
284#ifdef CONFIG_NET
285void audit_send_reply(int pid, int seq, int type, int done, int multi,
286 void *payload, int size)
287{
288 struct sk_buff *skb;
289 struct nlmsghdr *nlh;
290 int len = NLMSG_SPACE(size);
291 void *data;
292 int flags = multi ? NLM_F_MULTI : 0;
293 int t = done ? NLMSG_DONE : type;
294
295 skb = alloc_skb(len, GFP_KERNEL);
296 if (!skb)
297 goto nlmsg_failure;
298
299 nlh = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh));
300 nlh->nlmsg_flags = flags;
301 data = NLMSG_DATA(nlh);
302 memcpy(data, payload, size);
303 netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT);
304 return;
305
306nlmsg_failure: /* Used by NLMSG_PUT */
307 if (skb)
308 kfree_skb(skb);
309}
310
311/*
312 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
313 * control messages.
314 */
315static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type)
316{
317 int err = 0;
318
319 switch (msg_type) {
320 case AUDIT_GET:
321 case AUDIT_LIST:
322 case AUDIT_SET:
323 case AUDIT_ADD:
324 case AUDIT_DEL:
325 if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL))
326 err = -EPERM;
327 break;
328 case AUDIT_USER:
329 if (!cap_raised(eff_cap, CAP_AUDIT_WRITE))
330 err = -EPERM;
331 break;
332 default: /* bad msg */
333 err = -EINVAL;
334 }
335
336 return err;
337}
338
339static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
340{
341 u32 uid, pid, seq;
342 void *data;
343 struct audit_status *status_get, status_set;
344 int err;
345 struct audit_buffer *ab;
346 u16 msg_type = nlh->nlmsg_type;
347
348 err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type);
349 if (err)
350 return err;
351
352 pid = NETLINK_CREDS(skb)->pid;
353 uid = NETLINK_CREDS(skb)->uid;
354 seq = nlh->nlmsg_seq;
355 data = NLMSG_DATA(nlh);
356
357 switch (msg_type) {
358 case AUDIT_GET:
359 status_set.enabled = audit_enabled;
360 status_set.failure = audit_failure;
361 status_set.pid = audit_pid;
362 status_set.rate_limit = audit_rate_limit;
363 status_set.backlog_limit = audit_backlog_limit;
364 status_set.lost = atomic_read(&audit_lost);
365 status_set.backlog = atomic_read(&audit_backlog);
366 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
367 &status_set, sizeof(status_set));
368 break;
369 case AUDIT_SET:
370 if (nlh->nlmsg_len < sizeof(struct audit_status))
371 return -EINVAL;
372 status_get = (struct audit_status *)data;
373 if (status_get->mask & AUDIT_STATUS_ENABLED) {
374 err = audit_set_enabled(status_get->enabled);
375 if (err < 0) return err;
376 }
377 if (status_get->mask & AUDIT_STATUS_FAILURE) {
378 err = audit_set_failure(status_get->failure);
379 if (err < 0) return err;
380 }
381 if (status_get->mask & AUDIT_STATUS_PID) {
382 int old = audit_pid;
383 audit_pid = status_get->pid;
384 audit_log(current->audit_context,
385 "audit_pid=%d old=%d", audit_pid, old);
386 }
387 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
388 audit_set_rate_limit(status_get->rate_limit);
389 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
390 audit_set_backlog_limit(status_get->backlog_limit);
391 break;
392 case AUDIT_USER:
393 ab = audit_log_start(NULL);
394 if (!ab)
395 break; /* audit_panic has been called */
396 audit_log_format(ab,
397 "user pid=%d uid=%d length=%d msg='%.1024s'",
398 pid, uid,
399 (int)(nlh->nlmsg_len
400 - ((char *)data - (char *)nlh)),
401 (char *)data);
402 ab->type = AUDIT_USER;
403 ab->pid = pid;
404 audit_log_end(ab);
405 break;
406 case AUDIT_ADD:
407 case AUDIT_DEL:
408 if (nlh->nlmsg_len < sizeof(struct audit_rule))
409 return -EINVAL;
410 /* fallthrough */
411 case AUDIT_LIST:
412#ifdef CONFIG_AUDITSYSCALL
413 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
414 uid, seq, data);
415#else
416 err = -EOPNOTSUPP;
417#endif
418 break;
419 default:
420 err = -EINVAL;
421 break;
422 }
423
424 return err < 0 ? err : 0;
425}
426
427/* Get message from skb (based on rtnetlink_rcv_skb). Each message is
428 * processed by audit_receive_msg. Malformed skbs with wrong length are
429 * discarded silently. */
430static int audit_receive_skb(struct sk_buff *skb)
431{
432 int err;
433 struct nlmsghdr *nlh;
434 u32 rlen;
435
436 while (skb->len >= NLMSG_SPACE(0)) {
437 nlh = (struct nlmsghdr *)skb->data;
438 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
439 return 0;
440 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
441 if (rlen > skb->len)
442 rlen = skb->len;
443 if ((err = audit_receive_msg(skb, nlh))) {
444 netlink_ack(skb, nlh, err);
445 } else if (nlh->nlmsg_flags & NLM_F_ACK)
446 netlink_ack(skb, nlh, 0);
447 skb_pull(skb, rlen);
448 }
449 return 0;
450}
451
452/* Receive messages from netlink socket. */
453static void audit_receive(struct sock *sk, int length)
454{
455 struct sk_buff *skb;
456
457 if (down_trylock(&audit_netlink_sem))
458 return;
459
460 /* FIXME: this must not cause starvation */
461 while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
462 if (audit_receive_skb(skb) && skb->len)
463 skb_queue_head(&sk->sk_receive_queue, skb);
464 else
465 kfree_skb(skb);
466 }
467 up(&audit_netlink_sem);
468}
469
470/* Move data from tmp buffer into an skb. This is an extra copy, and
471 * that is unfortunate. However, the copy will only occur when a record
472 * is being written to user space, which is already a high-overhead
473 * operation. (Elimination of the copy is possible, for example, by
474 * writing directly into a pre-allocated skb, at the cost of wasting
475 * memory. */
476static void audit_log_move(struct audit_buffer *ab)
477{
478 struct sk_buff *skb;
479 char *start;
480 int extra = ab->nlh ? 0 : NLMSG_SPACE(0);
481
482 /* possible resubmission */
483 if (ab->len == 0)
484 return;
485
486 skb = skb_peek(&ab->sklist);
487 if (!skb || skb_tailroom(skb) <= ab->len + extra) {
488 skb = alloc_skb(2 * ab->len + extra, GFP_ATOMIC);
489 if (!skb) {
490 ab->len = 0; /* Lose information in ab->tmp */
491 audit_log_lost("out of memory in audit_log_move");
492 return;
493 }
494 __skb_queue_tail(&ab->sklist, skb);
495 if (!ab->nlh)
496 ab->nlh = (struct nlmsghdr *)skb_put(skb,
497 NLMSG_SPACE(0));
498 }
499 start = skb_put(skb, ab->len);
500 memcpy(start, ab->tmp, ab->len);
501 ab->len = 0;
502}
503
504/* Iterate over the skbuff in the audit_buffer, sending their contents
505 * to user space. */
506static inline int audit_log_drain(struct audit_buffer *ab)
507{
508 struct sk_buff *skb;
509
510 while ((skb = skb_dequeue(&ab->sklist))) {
511 int retval = 0;
512
513 if (audit_pid) {
514 if (ab->nlh) {
515 ab->nlh->nlmsg_len = ab->total;
516 ab->nlh->nlmsg_type = ab->type;
517 ab->nlh->nlmsg_flags = 0;
518 ab->nlh->nlmsg_seq = 0;
519 ab->nlh->nlmsg_pid = ab->pid;
520 }
521 skb_get(skb); /* because netlink_* frees */
522 retval = netlink_unicast(audit_sock, skb, audit_pid,
523 MSG_DONTWAIT);
524 }
525 if (retval == -EAGAIN && ab->count < 5) {
526 ++ab->count;
527 skb_queue_tail(&ab->sklist, skb);
528 audit_log_end_irq(ab);
529 return 1;
530 }
531 if (retval < 0) {
532 if (retval == -ECONNREFUSED) {
533 printk(KERN_ERR
534 "audit: *NO* daemon at audit_pid=%d\n",
535 audit_pid);
536 audit_pid = 0;
537 } else
538 audit_log_lost("netlink socket too busy");
539 }
540 if (!audit_pid) { /* No daemon */
541 int offset = ab->nlh ? NLMSG_SPACE(0) : 0;
542 int len = skb->len - offset;
543 printk(KERN_ERR "%*.*s\n",
544 len, len, skb->data + offset);
545 }
546 kfree_skb(skb);
547 ab->nlh = NULL;
548 }
549 return 0;
550}
551
552/* Initialize audit support at boot time. */
553static int __init audit_init(void)
554{
555 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
556 audit_default ? "enabled" : "disabled");
557 audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive);
558 if (!audit_sock)
559 audit_panic("cannot initialize netlink socket");
560
561 audit_initialized = 1;
562 audit_enabled = audit_default;
563 audit_log(NULL, "initialized");
564 return 0;
565}
566
567#else
568/* Without CONFIG_NET, we have no skbuffs. For now, print what we have
569 * in the buffer. */
570static void audit_log_move(struct audit_buffer *ab)
571{
572 printk(KERN_ERR "%*.*s\n", ab->len, ab->len, ab->tmp);
573 ab->len = 0;
574}
575
576static inline int audit_log_drain(struct audit_buffer *ab)
577{
578 return 0;
579}
580
581/* Initialize audit support at boot time. */
582int __init audit_init(void)
583{
584 printk(KERN_INFO "audit: initializing WITHOUT netlink support\n");
585 audit_sock = NULL;
586 audit_pid = 0;
587
588 audit_initialized = 1;
589 audit_enabled = audit_default;
590 audit_log(NULL, "initialized");
591 return 0;
592}
593#endif
594
595__initcall(audit_init);
596
597/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
598static int __init audit_enable(char *str)
599{
600 audit_default = !!simple_strtol(str, NULL, 0);
601 printk(KERN_INFO "audit: %s%s\n",
602 audit_default ? "enabled" : "disabled",
603 audit_initialized ? "" : " (after initialization)");
604 if (audit_initialized)
605 audit_enabled = audit_default;
606 return 0;
607}
608
609__setup("audit=", audit_enable);
610
611
612/* Obtain an audit buffer. This routine does locking to obtain the
613 * audit buffer, but then no locking is required for calls to
614 * audit_log_*format. If the tsk is a task that is currently in a
615 * syscall, then the syscall is marked as auditable and an audit record
616 * will be written at syscall exit. If there is no associated task, tsk
617 * should be NULL. */
618struct audit_buffer *audit_log_start(struct audit_context *ctx)
619{
620 struct audit_buffer *ab = NULL;
621 unsigned long flags;
622 struct timespec t;
623 int serial = 0;
624
625 if (!audit_initialized)
626 return NULL;
627
628 if (audit_backlog_limit
629 && atomic_read(&audit_backlog) > audit_backlog_limit) {
630 if (audit_rate_check())
631 printk(KERN_WARNING
632 "audit: audit_backlog=%d > "
633 "audit_backlog_limit=%d\n",
634 atomic_read(&audit_backlog),
635 audit_backlog_limit);
636 audit_log_lost("backlog limit exceeded");
637 return NULL;
638 }
639
640 spin_lock_irqsave(&audit_freelist_lock, flags);
641 if (!list_empty(&audit_freelist)) {
642 ab = list_entry(audit_freelist.next,
643 struct audit_buffer, list);
644 list_del(&ab->list);
645 --audit_freelist_count;
646 }
647 spin_unlock_irqrestore(&audit_freelist_lock, flags);
648
649 if (!ab)
650 ab = kmalloc(sizeof(*ab), GFP_ATOMIC);
651 if (!ab) {
652 audit_log_lost("out of memory in audit_log_start");
653 return NULL;
654 }
655
656 atomic_inc(&audit_backlog);
657 skb_queue_head_init(&ab->sklist);
658
659 ab->ctx = ctx;
660 ab->len = 0;
661 ab->nlh = NULL;
662 ab->total = 0;
663 ab->type = AUDIT_KERNEL;
664 ab->pid = 0;
665 ab->count = 0;
666
667#ifdef CONFIG_AUDITSYSCALL
668 if (ab->ctx)
669 audit_get_stamp(ab->ctx, &t, &serial);
670 else
671#endif
672 t = CURRENT_TIME;
673
674 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
675 t.tv_sec, t.tv_nsec/1000000, serial);
676 return ab;
677}
678
679
680/* Format an audit message into the audit buffer. If there isn't enough
681 * room in the audit buffer, more room will be allocated and vsnprint
682 * will be called a second time. Currently, we assume that a printk
683 * can't format message larger than 1024 bytes, so we don't either. */
684static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
685 va_list args)
686{
687 int len, avail;
688
689 if (!ab)
690 return;
691
692 avail = sizeof(ab->tmp) - ab->len;
693 if (avail <= 0) {
694 audit_log_move(ab);
695 avail = sizeof(ab->tmp) - ab->len;
696 }
697 len = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
698 if (len >= avail) {
699 /* The printk buffer is 1024 bytes long, so if we get
700 * here and AUDIT_BUFSIZ is at least 1024, then we can
701 * log everything that printk could have logged. */
702 audit_log_move(ab);
703 avail = sizeof(ab->tmp) - ab->len;
704 len = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
705 }
706 ab->len += (len < avail) ? len : avail;
707 ab->total += (len < avail) ? len : avail;
708}
709
710/* Format a message into the audit buffer. All the work is done in
711 * audit_log_vformat. */
712void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
713{
714 va_list args;
715
716 if (!ab)
717 return;
718 va_start(args, fmt);
719 audit_log_vformat(ab, fmt, args);
720 va_end(args);
721}
722
723/* This is a helper-function to print the d_path without using a static
724 * buffer or allocating another buffer in addition to the one in
725 * audit_buffer. */
726void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
727 struct dentry *dentry, struct vfsmount *vfsmnt)
728{
729 char *p;
730 int len, avail;
731
732 if (prefix) audit_log_format(ab, " %s", prefix);
733
734 if (ab->len > 128)
735 audit_log_move(ab);
736 avail = sizeof(ab->tmp) - ab->len;
737 p = d_path(dentry, vfsmnt, ab->tmp + ab->len, avail);
738 if (IS_ERR(p)) {
739 /* FIXME: can we save some information here? */
740 audit_log_format(ab, "<toolong>");
741 } else {
742 /* path isn't at start of buffer */
743 len = (ab->tmp + sizeof(ab->tmp) - 1) - p;
744 memmove(ab->tmp + ab->len, p, len);
745 ab->len += len;
746 ab->total += len;
747 }
748}
749
750/* Remove queued messages from the audit_txlist and send them to userspace. */
751static void audit_tasklet_handler(unsigned long arg)
752{
753 LIST_HEAD(list);
754 struct audit_buffer *ab;
755 unsigned long flags;
756
757 spin_lock_irqsave(&audit_txlist_lock, flags);
758 list_splice_init(&audit_txlist, &list);
759 spin_unlock_irqrestore(&audit_txlist_lock, flags);
760
761 while (!list_empty(&list)) {
762 ab = list_entry(list.next, struct audit_buffer, list);
763 list_del(&ab->list);
764 audit_log_end_fast(ab);
765 }
766}
767
768static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0);
769
770/* The netlink_* functions cannot be called inside an irq context, so
771 * the audit buffer is places on a queue and a tasklet is scheduled to
772 * remove them from the queue outside the irq context. May be called in
773 * any context. */
774static void audit_log_end_irq(struct audit_buffer *ab)
775{
776 unsigned long flags;
777
778 if (!ab)
779 return;
780 spin_lock_irqsave(&audit_txlist_lock, flags);
781 list_add_tail(&ab->list, &audit_txlist);
782 spin_unlock_irqrestore(&audit_txlist_lock, flags);
783
784 tasklet_schedule(&audit_tasklet);
785}
786
787/* Send the message in the audit buffer directly to user space. May not
788 * be called in an irq context. */
789static void audit_log_end_fast(struct audit_buffer *ab)
790{
791 unsigned long flags;
792
793 BUG_ON(in_irq());
794 if (!ab)
795 return;
796 if (!audit_rate_check()) {
797 audit_log_lost("rate limit exceeded");
798 } else {
799 audit_log_move(ab);
800 if (audit_log_drain(ab))
801 return;
802 }
803
804 atomic_dec(&audit_backlog);
805 spin_lock_irqsave(&audit_freelist_lock, flags);
806 if (++audit_freelist_count > AUDIT_MAXFREE)
807 kfree(ab);
808 else
809 list_add(&ab->list, &audit_freelist);
810 spin_unlock_irqrestore(&audit_freelist_lock, flags);
811}
812
813/* Send or queue the message in the audit buffer, depending on the
814 * current context. (A convenience function that may be called in any
815 * context.) */
816void audit_log_end(struct audit_buffer *ab)
817{
818 if (in_irq())
819 audit_log_end_irq(ab);
820 else
821 audit_log_end_fast(ab);
822}
823
824/* Log an audit record. This is a convenience function that calls
825 * audit_log_start, audit_log_vformat, and audit_log_end. It may be
826 * called in any context. */
827void audit_log(struct audit_context *ctx, const char *fmt, ...)
828{
829 struct audit_buffer *ab;
830 va_list args;
831
832 ab = audit_log_start(ctx);
833 if (ab) {
834 va_start(args, fmt);
835 audit_log_vformat(ab, fmt, args);
836 va_end(args);
837 audit_log_end(ab);
838 }
839}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-22 08:53:24 -0500