xref: /openbmc/linux/kernel/audit.c (revision 6774def6)
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
45 
46 #include <linux/init.h>
47 #include <linux/types.h>
48 #include <linux/atomic.h>
49 #include <linux/mm.h>
50 #include <linux/export.h>
51 #include <linux/slab.h>
52 #include <linux/err.h>
53 #include <linux/kthread.h>
54 #include <linux/kernel.h>
55 #include <linux/syscalls.h>
56 
57 #include <linux/audit.h>
58 
59 #include <net/sock.h>
60 #include <net/netlink.h>
61 #include <linux/skbuff.h>
62 #ifdef CONFIG_SECURITY
63 #include <linux/security.h>
64 #endif
65 #include <linux/freezer.h>
66 #include <linux/tty.h>
67 #include <linux/pid_namespace.h>
68 #include <net/netns/generic.h>
69 
70 #include "audit.h"
71 
72 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
73  * (Initialization happens after skb_init is called.) */
74 #define AUDIT_DISABLED		-1
75 #define AUDIT_UNINITIALIZED	0
76 #define AUDIT_INITIALIZED	1
77 static int	audit_initialized;
78 
79 #define AUDIT_OFF	0
80 #define AUDIT_ON	1
81 #define AUDIT_LOCKED	2
82 u32		audit_enabled;
83 u32		audit_ever_enabled;
84 
85 EXPORT_SYMBOL_GPL(audit_enabled);
86 
87 /* Default state when kernel boots without any parameters. */
88 static u32	audit_default;
89 
90 /* If auditing cannot proceed, audit_failure selects what happens. */
91 static u32	audit_failure = AUDIT_FAIL_PRINTK;
92 
93 /*
94  * If audit records are to be written to the netlink socket, audit_pid
95  * contains the pid of the auditd process and audit_nlk_portid contains
96  * the portid to use to send netlink messages to that process.
97  */
98 int		audit_pid;
99 static __u32	audit_nlk_portid;
100 
101 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
102  * to that number per second.  This prevents DoS attacks, but results in
103  * audit records being dropped. */
104 static u32	audit_rate_limit;
105 
106 /* Number of outstanding audit_buffers allowed.
107  * When set to zero, this means unlimited. */
108 static u32	audit_backlog_limit = 64;
109 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
110 static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
111 static u32	audit_backlog_wait_overflow = 0;
112 
113 /* The identity of the user shutting down the audit system. */
114 kuid_t		audit_sig_uid = INVALID_UID;
115 pid_t		audit_sig_pid = -1;
116 u32		audit_sig_sid = 0;
117 
118 /* Records can be lost in several ways:
119    0) [suppressed in audit_alloc]
120    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
121    2) out of memory in audit_log_move [alloc_skb]
122    3) suppressed due to audit_rate_limit
123    4) suppressed due to audit_backlog_limit
124 */
125 static atomic_t    audit_lost = ATOMIC_INIT(0);
126 
127 /* The netlink socket. */
128 static struct sock *audit_sock;
129 static int audit_net_id;
130 
131 /* Hash for inode-based rules */
132 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
133 
134 /* The audit_freelist is a list of pre-allocated audit buffers (if more
135  * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
136  * being placed on the freelist). */
137 static DEFINE_SPINLOCK(audit_freelist_lock);
138 static int	   audit_freelist_count;
139 static LIST_HEAD(audit_freelist);
140 
141 static struct sk_buff_head audit_skb_queue;
142 /* queue of skbs to send to auditd when/if it comes back */
143 static struct sk_buff_head audit_skb_hold_queue;
144 static struct task_struct *kauditd_task;
145 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
146 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
147 
148 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
149 				   .mask = -1,
150 				   .features = 0,
151 				   .lock = 0,};
152 
153 static char *audit_feature_names[2] = {
154 	"only_unset_loginuid",
155 	"loginuid_immutable",
156 };
157 
158 
159 /* Serialize requests from userspace. */
160 DEFINE_MUTEX(audit_cmd_mutex);
161 
162 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
163  * audit records.  Since printk uses a 1024 byte buffer, this buffer
164  * should be at least that large. */
165 #define AUDIT_BUFSIZ 1024
166 
167 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
168  * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
169 #define AUDIT_MAXFREE  (2*NR_CPUS)
170 
171 /* The audit_buffer is used when formatting an audit record.  The caller
172  * locks briefly to get the record off the freelist or to allocate the
173  * buffer, and locks briefly to send the buffer to the netlink layer or
174  * to place it on a transmit queue.  Multiple audit_buffers can be in
175  * use simultaneously. */
176 struct audit_buffer {
177 	struct list_head     list;
178 	struct sk_buff       *skb;	/* formatted skb ready to send */
179 	struct audit_context *ctx;	/* NULL or associated context */
180 	gfp_t		     gfp_mask;
181 };
182 
183 struct audit_reply {
184 	__u32 portid;
185 	struct net *net;
186 	struct sk_buff *skb;
187 };
188 
189 static void audit_set_portid(struct audit_buffer *ab, __u32 portid)
190 {
191 	if (ab) {
192 		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
193 		nlh->nlmsg_pid = portid;
194 	}
195 }
196 
197 void audit_panic(const char *message)
198 {
199 	switch (audit_failure) {
200 	case AUDIT_FAIL_SILENT:
201 		break;
202 	case AUDIT_FAIL_PRINTK:
203 		if (printk_ratelimit())
204 			pr_err("%s\n", message);
205 		break;
206 	case AUDIT_FAIL_PANIC:
207 		/* test audit_pid since printk is always losey, why bother? */
208 		if (audit_pid)
209 			panic("audit: %s\n", message);
210 		break;
211 	}
212 }
213 
214 static inline int audit_rate_check(void)
215 {
216 	static unsigned long	last_check = 0;
217 	static int		messages   = 0;
218 	static DEFINE_SPINLOCK(lock);
219 	unsigned long		flags;
220 	unsigned long		now;
221 	unsigned long		elapsed;
222 	int			retval	   = 0;
223 
224 	if (!audit_rate_limit) return 1;
225 
226 	spin_lock_irqsave(&lock, flags);
227 	if (++messages < audit_rate_limit) {
228 		retval = 1;
229 	} else {
230 		now     = jiffies;
231 		elapsed = now - last_check;
232 		if (elapsed > HZ) {
233 			last_check = now;
234 			messages   = 0;
235 			retval     = 1;
236 		}
237 	}
238 	spin_unlock_irqrestore(&lock, flags);
239 
240 	return retval;
241 }
242 
243 /**
244  * audit_log_lost - conditionally log lost audit message event
245  * @message: the message stating reason for lost audit message
246  *
247  * Emit at least 1 message per second, even if audit_rate_check is
248  * throttling.
249  * Always increment the lost messages counter.
250 */
251 void audit_log_lost(const char *message)
252 {
253 	static unsigned long	last_msg = 0;
254 	static DEFINE_SPINLOCK(lock);
255 	unsigned long		flags;
256 	unsigned long		now;
257 	int			print;
258 
259 	atomic_inc(&audit_lost);
260 
261 	print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
262 
263 	if (!print) {
264 		spin_lock_irqsave(&lock, flags);
265 		now = jiffies;
266 		if (now - last_msg > HZ) {
267 			print = 1;
268 			last_msg = now;
269 		}
270 		spin_unlock_irqrestore(&lock, flags);
271 	}
272 
273 	if (print) {
274 		if (printk_ratelimit())
275 			pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
276 				atomic_read(&audit_lost),
277 				audit_rate_limit,
278 				audit_backlog_limit);
279 		audit_panic(message);
280 	}
281 }
282 
283 static int audit_log_config_change(char *function_name, u32 new, u32 old,
284 				   int allow_changes)
285 {
286 	struct audit_buffer *ab;
287 	int rc = 0;
288 
289 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
290 	if (unlikely(!ab))
291 		return rc;
292 	audit_log_format(ab, "%s=%u old=%u", function_name, new, old);
293 	audit_log_session_info(ab);
294 	rc = audit_log_task_context(ab);
295 	if (rc)
296 		allow_changes = 0; /* Something weird, deny request */
297 	audit_log_format(ab, " res=%d", allow_changes);
298 	audit_log_end(ab);
299 	return rc;
300 }
301 
302 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
303 {
304 	int allow_changes, rc = 0;
305 	u32 old = *to_change;
306 
307 	/* check if we are locked */
308 	if (audit_enabled == AUDIT_LOCKED)
309 		allow_changes = 0;
310 	else
311 		allow_changes = 1;
312 
313 	if (audit_enabled != AUDIT_OFF) {
314 		rc = audit_log_config_change(function_name, new, old, allow_changes);
315 		if (rc)
316 			allow_changes = 0;
317 	}
318 
319 	/* If we are allowed, make the change */
320 	if (allow_changes == 1)
321 		*to_change = new;
322 	/* Not allowed, update reason */
323 	else if (rc == 0)
324 		rc = -EPERM;
325 	return rc;
326 }
327 
328 static int audit_set_rate_limit(u32 limit)
329 {
330 	return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
331 }
332 
333 static int audit_set_backlog_limit(u32 limit)
334 {
335 	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
336 }
337 
338 static int audit_set_backlog_wait_time(u32 timeout)
339 {
340 	return audit_do_config_change("audit_backlog_wait_time",
341 				      &audit_backlog_wait_time, timeout);
342 }
343 
344 static int audit_set_enabled(u32 state)
345 {
346 	int rc;
347 	if (state < AUDIT_OFF || state > AUDIT_LOCKED)
348 		return -EINVAL;
349 
350 	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
351 	if (!rc)
352 		audit_ever_enabled |= !!state;
353 
354 	return rc;
355 }
356 
357 static int audit_set_failure(u32 state)
358 {
359 	if (state != AUDIT_FAIL_SILENT
360 	    && state != AUDIT_FAIL_PRINTK
361 	    && state != AUDIT_FAIL_PANIC)
362 		return -EINVAL;
363 
364 	return audit_do_config_change("audit_failure", &audit_failure, state);
365 }
366 
367 /*
368  * Queue skbs to be sent to auditd when/if it comes back.  These skbs should
369  * already have been sent via prink/syslog and so if these messages are dropped
370  * it is not a huge concern since we already passed the audit_log_lost()
371  * notification and stuff.  This is just nice to get audit messages during
372  * boot before auditd is running or messages generated while auditd is stopped.
373  * This only holds messages is audit_default is set, aka booting with audit=1
374  * or building your kernel that way.
375  */
376 static void audit_hold_skb(struct sk_buff *skb)
377 {
378 	if (audit_default &&
379 	    (!audit_backlog_limit ||
380 	     skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit))
381 		skb_queue_tail(&audit_skb_hold_queue, skb);
382 	else
383 		kfree_skb(skb);
384 }
385 
386 /*
387  * For one reason or another this nlh isn't getting delivered to the userspace
388  * audit daemon, just send it to printk.
389  */
390 static void audit_printk_skb(struct sk_buff *skb)
391 {
392 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
393 	char *data = nlmsg_data(nlh);
394 
395 	if (nlh->nlmsg_type != AUDIT_EOE) {
396 		if (printk_ratelimit())
397 			pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
398 		else
399 			audit_log_lost("printk limit exceeded");
400 	}
401 
402 	audit_hold_skb(skb);
403 }
404 
405 static void kauditd_send_skb(struct sk_buff *skb)
406 {
407 	int err;
408 	/* take a reference in case we can't send it and we want to hold it */
409 	skb_get(skb);
410 	err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
411 	if (err < 0) {
412 		BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
413 		if (audit_pid) {
414 			pr_err("*NO* daemon at audit_pid=%d\n", audit_pid);
415 			audit_log_lost("auditd disappeared");
416 			audit_pid = 0;
417 			audit_sock = NULL;
418 		}
419 		/* we might get lucky and get this in the next auditd */
420 		audit_hold_skb(skb);
421 	} else
422 		/* drop the extra reference if sent ok */
423 		consume_skb(skb);
424 }
425 
426 /*
427  * kauditd_send_multicast_skb - send the skb to multicast userspace listeners
428  *
429  * This function doesn't consume an skb as might be expected since it has to
430  * copy it anyways.
431  */
432 static void kauditd_send_multicast_skb(struct sk_buff *skb)
433 {
434 	struct sk_buff		*copy;
435 	struct audit_net	*aunet = net_generic(&init_net, audit_net_id);
436 	struct sock		*sock = aunet->nlsk;
437 
438 	if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
439 		return;
440 
441 	/*
442 	 * The seemingly wasteful skb_copy() rather than bumping the refcount
443 	 * using skb_get() is necessary because non-standard mods are made to
444 	 * the skb by the original kaudit unicast socket send routine.  The
445 	 * existing auditd daemon assumes this breakage.  Fixing this would
446 	 * require co-ordinating a change in the established protocol between
447 	 * the kaudit kernel subsystem and the auditd userspace code.  There is
448 	 * no reason for new multicast clients to continue with this
449 	 * non-compliance.
450 	 */
451 	copy = skb_copy(skb, GFP_KERNEL);
452 	if (!copy)
453 		return;
454 
455 	nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
456 }
457 
458 /*
459  * flush_hold_queue - empty the hold queue if auditd appears
460  *
461  * If auditd just started, drain the queue of messages already
462  * sent to syslog/printk.  Remember loss here is ok.  We already
463  * called audit_log_lost() if it didn't go out normally.  so the
464  * race between the skb_dequeue and the next check for audit_pid
465  * doesn't matter.
466  *
467  * If you ever find kauditd to be too slow we can get a perf win
468  * by doing our own locking and keeping better track if there
469  * are messages in this queue.  I don't see the need now, but
470  * in 5 years when I want to play with this again I'll see this
471  * note and still have no friggin idea what i'm thinking today.
472  */
473 static void flush_hold_queue(void)
474 {
475 	struct sk_buff *skb;
476 
477 	if (!audit_default || !audit_pid)
478 		return;
479 
480 	skb = skb_dequeue(&audit_skb_hold_queue);
481 	if (likely(!skb))
482 		return;
483 
484 	while (skb && audit_pid) {
485 		kauditd_send_skb(skb);
486 		skb = skb_dequeue(&audit_skb_hold_queue);
487 	}
488 
489 	/*
490 	 * if auditd just disappeared but we
491 	 * dequeued an skb we need to drop ref
492 	 */
493 	if (skb)
494 		consume_skb(skb);
495 }
496 
497 static int kauditd_thread(void *dummy)
498 {
499 	set_freezable();
500 	while (!kthread_should_stop()) {
501 		struct sk_buff *skb;
502 		DECLARE_WAITQUEUE(wait, current);
503 
504 		flush_hold_queue();
505 
506 		skb = skb_dequeue(&audit_skb_queue);
507 
508 		if (skb) {
509 			if (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit)
510 				wake_up(&audit_backlog_wait);
511 			if (audit_pid)
512 				kauditd_send_skb(skb);
513 			else
514 				audit_printk_skb(skb);
515 			continue;
516 		}
517 		set_current_state(TASK_INTERRUPTIBLE);
518 		add_wait_queue(&kauditd_wait, &wait);
519 
520 		if (!skb_queue_len(&audit_skb_queue)) {
521 			try_to_freeze();
522 			schedule();
523 		}
524 
525 		__set_current_state(TASK_RUNNING);
526 		remove_wait_queue(&kauditd_wait, &wait);
527 	}
528 	return 0;
529 }
530 
531 int audit_send_list(void *_dest)
532 {
533 	struct audit_netlink_list *dest = _dest;
534 	struct sk_buff *skb;
535 	struct net *net = dest->net;
536 	struct audit_net *aunet = net_generic(net, audit_net_id);
537 
538 	/* wait for parent to finish and send an ACK */
539 	mutex_lock(&audit_cmd_mutex);
540 	mutex_unlock(&audit_cmd_mutex);
541 
542 	while ((skb = __skb_dequeue(&dest->q)) != NULL)
543 		netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
544 
545 	put_net(net);
546 	kfree(dest);
547 
548 	return 0;
549 }
550 
551 struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
552 				 int multi, const void *payload, int size)
553 {
554 	struct sk_buff	*skb;
555 	struct nlmsghdr	*nlh;
556 	void		*data;
557 	int		flags = multi ? NLM_F_MULTI : 0;
558 	int		t     = done  ? NLMSG_DONE  : type;
559 
560 	skb = nlmsg_new(size, GFP_KERNEL);
561 	if (!skb)
562 		return NULL;
563 
564 	nlh	= nlmsg_put(skb, portid, seq, t, size, flags);
565 	if (!nlh)
566 		goto out_kfree_skb;
567 	data = nlmsg_data(nlh);
568 	memcpy(data, payload, size);
569 	return skb;
570 
571 out_kfree_skb:
572 	kfree_skb(skb);
573 	return NULL;
574 }
575 
576 static int audit_send_reply_thread(void *arg)
577 {
578 	struct audit_reply *reply = (struct audit_reply *)arg;
579 	struct net *net = reply->net;
580 	struct audit_net *aunet = net_generic(net, audit_net_id);
581 
582 	mutex_lock(&audit_cmd_mutex);
583 	mutex_unlock(&audit_cmd_mutex);
584 
585 	/* Ignore failure. It'll only happen if the sender goes away,
586 	   because our timeout is set to infinite. */
587 	netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
588 	put_net(net);
589 	kfree(reply);
590 	return 0;
591 }
592 /**
593  * audit_send_reply - send an audit reply message via netlink
594  * @request_skb: skb of request we are replying to (used to target the reply)
595  * @seq: sequence number
596  * @type: audit message type
597  * @done: done (last) flag
598  * @multi: multi-part message flag
599  * @payload: payload data
600  * @size: payload size
601  *
602  * Allocates an skb, builds the netlink message, and sends it to the port id.
603  * No failure notifications.
604  */
605 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
606 			     int multi, const void *payload, int size)
607 {
608 	u32 portid = NETLINK_CB(request_skb).portid;
609 	struct net *net = sock_net(NETLINK_CB(request_skb).sk);
610 	struct sk_buff *skb;
611 	struct task_struct *tsk;
612 	struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
613 					    GFP_KERNEL);
614 
615 	if (!reply)
616 		return;
617 
618 	skb = audit_make_reply(portid, seq, type, done, multi, payload, size);
619 	if (!skb)
620 		goto out;
621 
622 	reply->net = get_net(net);
623 	reply->portid = portid;
624 	reply->skb = skb;
625 
626 	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
627 	if (!IS_ERR(tsk))
628 		return;
629 	kfree_skb(skb);
630 out:
631 	kfree(reply);
632 }
633 
634 /*
635  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
636  * control messages.
637  */
638 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
639 {
640 	int err = 0;
641 
642 	/* Only support initial user namespace for now. */
643 	/*
644 	 * We return ECONNREFUSED because it tricks userspace into thinking
645 	 * that audit was not configured into the kernel.  Lots of users
646 	 * configure their PAM stack (because that's what the distro does)
647 	 * to reject login if unable to send messages to audit.  If we return
648 	 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
649 	 * configured in and will let login proceed.  If we return EPERM
650 	 * userspace will reject all logins.  This should be removed when we
651 	 * support non init namespaces!!
652 	 */
653 	if (current_user_ns() != &init_user_ns)
654 		return -ECONNREFUSED;
655 
656 	switch (msg_type) {
657 	case AUDIT_LIST:
658 	case AUDIT_ADD:
659 	case AUDIT_DEL:
660 		return -EOPNOTSUPP;
661 	case AUDIT_GET:
662 	case AUDIT_SET:
663 	case AUDIT_GET_FEATURE:
664 	case AUDIT_SET_FEATURE:
665 	case AUDIT_LIST_RULES:
666 	case AUDIT_ADD_RULE:
667 	case AUDIT_DEL_RULE:
668 	case AUDIT_SIGNAL_INFO:
669 	case AUDIT_TTY_GET:
670 	case AUDIT_TTY_SET:
671 	case AUDIT_TRIM:
672 	case AUDIT_MAKE_EQUIV:
673 		/* Only support auditd and auditctl in initial pid namespace
674 		 * for now. */
675 		if ((task_active_pid_ns(current) != &init_pid_ns))
676 			return -EPERM;
677 
678 		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
679 			err = -EPERM;
680 		break;
681 	case AUDIT_USER:
682 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
683 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
684 		if (!netlink_capable(skb, CAP_AUDIT_WRITE))
685 			err = -EPERM;
686 		break;
687 	default:  /* bad msg */
688 		err = -EINVAL;
689 	}
690 
691 	return err;
692 }
693 
694 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
695 {
696 	int rc = 0;
697 	uid_t uid = from_kuid(&init_user_ns, current_uid());
698 	pid_t pid = task_tgid_nr(current);
699 
700 	if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
701 		*ab = NULL;
702 		return rc;
703 	}
704 
705 	*ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
706 	if (unlikely(!*ab))
707 		return rc;
708 	audit_log_format(*ab, "pid=%d uid=%u", pid, uid);
709 	audit_log_session_info(*ab);
710 	audit_log_task_context(*ab);
711 
712 	return rc;
713 }
714 
715 int is_audit_feature_set(int i)
716 {
717 	return af.features & AUDIT_FEATURE_TO_MASK(i);
718 }
719 
720 
721 static int audit_get_feature(struct sk_buff *skb)
722 {
723 	u32 seq;
724 
725 	seq = nlmsg_hdr(skb)->nlmsg_seq;
726 
727 	audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
728 
729 	return 0;
730 }
731 
732 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
733 				     u32 old_lock, u32 new_lock, int res)
734 {
735 	struct audit_buffer *ab;
736 
737 	if (audit_enabled == AUDIT_OFF)
738 		return;
739 
740 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
741 	audit_log_task_info(ab, current);
742 	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
743 			 audit_feature_names[which], !!old_feature, !!new_feature,
744 			 !!old_lock, !!new_lock, res);
745 	audit_log_end(ab);
746 }
747 
748 static int audit_set_feature(struct sk_buff *skb)
749 {
750 	struct audit_features *uaf;
751 	int i;
752 
753 	BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
754 	uaf = nlmsg_data(nlmsg_hdr(skb));
755 
756 	/* if there is ever a version 2 we should handle that here */
757 
758 	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
759 		u32 feature = AUDIT_FEATURE_TO_MASK(i);
760 		u32 old_feature, new_feature, old_lock, new_lock;
761 
762 		/* if we are not changing this feature, move along */
763 		if (!(feature & uaf->mask))
764 			continue;
765 
766 		old_feature = af.features & feature;
767 		new_feature = uaf->features & feature;
768 		new_lock = (uaf->lock | af.lock) & feature;
769 		old_lock = af.lock & feature;
770 
771 		/* are we changing a locked feature? */
772 		if (old_lock && (new_feature != old_feature)) {
773 			audit_log_feature_change(i, old_feature, new_feature,
774 						 old_lock, new_lock, 0);
775 			return -EPERM;
776 		}
777 	}
778 	/* nothing invalid, do the changes */
779 	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
780 		u32 feature = AUDIT_FEATURE_TO_MASK(i);
781 		u32 old_feature, new_feature, old_lock, new_lock;
782 
783 		/* if we are not changing this feature, move along */
784 		if (!(feature & uaf->mask))
785 			continue;
786 
787 		old_feature = af.features & feature;
788 		new_feature = uaf->features & feature;
789 		old_lock = af.lock & feature;
790 		new_lock = (uaf->lock | af.lock) & feature;
791 
792 		if (new_feature != old_feature)
793 			audit_log_feature_change(i, old_feature, new_feature,
794 						 old_lock, new_lock, 1);
795 
796 		if (new_feature)
797 			af.features |= feature;
798 		else
799 			af.features &= ~feature;
800 		af.lock |= new_lock;
801 	}
802 
803 	return 0;
804 }
805 
806 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
807 {
808 	u32			seq;
809 	void			*data;
810 	int			err;
811 	struct audit_buffer	*ab;
812 	u16			msg_type = nlh->nlmsg_type;
813 	struct audit_sig_info   *sig_data;
814 	char			*ctx = NULL;
815 	u32			len;
816 
817 	err = audit_netlink_ok(skb, msg_type);
818 	if (err)
819 		return err;
820 
821 	/* As soon as there's any sign of userspace auditd,
822 	 * start kauditd to talk to it */
823 	if (!kauditd_task) {
824 		kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
825 		if (IS_ERR(kauditd_task)) {
826 			err = PTR_ERR(kauditd_task);
827 			kauditd_task = NULL;
828 			return err;
829 		}
830 	}
831 	seq  = nlh->nlmsg_seq;
832 	data = nlmsg_data(nlh);
833 
834 	switch (msg_type) {
835 	case AUDIT_GET: {
836 		struct audit_status	s;
837 		memset(&s, 0, sizeof(s));
838 		s.enabled		= audit_enabled;
839 		s.failure		= audit_failure;
840 		s.pid			= audit_pid;
841 		s.rate_limit		= audit_rate_limit;
842 		s.backlog_limit		= audit_backlog_limit;
843 		s.lost			= atomic_read(&audit_lost);
844 		s.backlog		= skb_queue_len(&audit_skb_queue);
845 		s.version		= AUDIT_VERSION_LATEST;
846 		s.backlog_wait_time	= audit_backlog_wait_time;
847 		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
848 		break;
849 	}
850 	case AUDIT_SET: {
851 		struct audit_status	s;
852 		memset(&s, 0, sizeof(s));
853 		/* guard against past and future API changes */
854 		memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
855 		if (s.mask & AUDIT_STATUS_ENABLED) {
856 			err = audit_set_enabled(s.enabled);
857 			if (err < 0)
858 				return err;
859 		}
860 		if (s.mask & AUDIT_STATUS_FAILURE) {
861 			err = audit_set_failure(s.failure);
862 			if (err < 0)
863 				return err;
864 		}
865 		if (s.mask & AUDIT_STATUS_PID) {
866 			int new_pid = s.pid;
867 
868 			if ((!new_pid) && (task_tgid_vnr(current) != audit_pid))
869 				return -EACCES;
870 			if (audit_enabled != AUDIT_OFF)
871 				audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
872 			audit_pid = new_pid;
873 			audit_nlk_portid = NETLINK_CB(skb).portid;
874 			audit_sock = skb->sk;
875 		}
876 		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
877 			err = audit_set_rate_limit(s.rate_limit);
878 			if (err < 0)
879 				return err;
880 		}
881 		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
882 			err = audit_set_backlog_limit(s.backlog_limit);
883 			if (err < 0)
884 				return err;
885 		}
886 		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
887 			if (sizeof(s) > (size_t)nlh->nlmsg_len)
888 				return -EINVAL;
889 			if (s.backlog_wait_time < 0 ||
890 			    s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
891 				return -EINVAL;
892 			err = audit_set_backlog_wait_time(s.backlog_wait_time);
893 			if (err < 0)
894 				return err;
895 		}
896 		break;
897 	}
898 	case AUDIT_GET_FEATURE:
899 		err = audit_get_feature(skb);
900 		if (err)
901 			return err;
902 		break;
903 	case AUDIT_SET_FEATURE:
904 		err = audit_set_feature(skb);
905 		if (err)
906 			return err;
907 		break;
908 	case AUDIT_USER:
909 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
910 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
911 		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
912 			return 0;
913 
914 		err = audit_filter_user(msg_type);
915 		if (err == 1) { /* match or error */
916 			err = 0;
917 			if (msg_type == AUDIT_USER_TTY) {
918 				err = tty_audit_push_current();
919 				if (err)
920 					break;
921 			}
922 			mutex_unlock(&audit_cmd_mutex);
923 			audit_log_common_recv_msg(&ab, msg_type);
924 			if (msg_type != AUDIT_USER_TTY)
925 				audit_log_format(ab, " msg='%.*s'",
926 						 AUDIT_MESSAGE_TEXT_MAX,
927 						 (char *)data);
928 			else {
929 				int size;
930 
931 				audit_log_format(ab, " data=");
932 				size = nlmsg_len(nlh);
933 				if (size > 0 &&
934 				    ((unsigned char *)data)[size - 1] == '\0')
935 					size--;
936 				audit_log_n_untrustedstring(ab, data, size);
937 			}
938 			audit_set_portid(ab, NETLINK_CB(skb).portid);
939 			audit_log_end(ab);
940 			mutex_lock(&audit_cmd_mutex);
941 		}
942 		break;
943 	case AUDIT_ADD_RULE:
944 	case AUDIT_DEL_RULE:
945 		if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
946 			return -EINVAL;
947 		if (audit_enabled == AUDIT_LOCKED) {
948 			audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
949 			audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
950 			audit_log_end(ab);
951 			return -EPERM;
952 		}
953 		err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
954 					   seq, data, nlmsg_len(nlh));
955 		break;
956 	case AUDIT_LIST_RULES:
957 		err = audit_list_rules_send(skb, seq);
958 		break;
959 	case AUDIT_TRIM:
960 		audit_trim_trees();
961 		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
962 		audit_log_format(ab, " op=trim res=1");
963 		audit_log_end(ab);
964 		break;
965 	case AUDIT_MAKE_EQUIV: {
966 		void *bufp = data;
967 		u32 sizes[2];
968 		size_t msglen = nlmsg_len(nlh);
969 		char *old, *new;
970 
971 		err = -EINVAL;
972 		if (msglen < 2 * sizeof(u32))
973 			break;
974 		memcpy(sizes, bufp, 2 * sizeof(u32));
975 		bufp += 2 * sizeof(u32);
976 		msglen -= 2 * sizeof(u32);
977 		old = audit_unpack_string(&bufp, &msglen, sizes[0]);
978 		if (IS_ERR(old)) {
979 			err = PTR_ERR(old);
980 			break;
981 		}
982 		new = audit_unpack_string(&bufp, &msglen, sizes[1]);
983 		if (IS_ERR(new)) {
984 			err = PTR_ERR(new);
985 			kfree(old);
986 			break;
987 		}
988 		/* OK, here comes... */
989 		err = audit_tag_tree(old, new);
990 
991 		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
992 
993 		audit_log_format(ab, " op=make_equiv old=");
994 		audit_log_untrustedstring(ab, old);
995 		audit_log_format(ab, " new=");
996 		audit_log_untrustedstring(ab, new);
997 		audit_log_format(ab, " res=%d", !err);
998 		audit_log_end(ab);
999 		kfree(old);
1000 		kfree(new);
1001 		break;
1002 	}
1003 	case AUDIT_SIGNAL_INFO:
1004 		len = 0;
1005 		if (audit_sig_sid) {
1006 			err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1007 			if (err)
1008 				return err;
1009 		}
1010 		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1011 		if (!sig_data) {
1012 			if (audit_sig_sid)
1013 				security_release_secctx(ctx, len);
1014 			return -ENOMEM;
1015 		}
1016 		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1017 		sig_data->pid = audit_sig_pid;
1018 		if (audit_sig_sid) {
1019 			memcpy(sig_data->ctx, ctx, len);
1020 			security_release_secctx(ctx, len);
1021 		}
1022 		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1023 				 sig_data, sizeof(*sig_data) + len);
1024 		kfree(sig_data);
1025 		break;
1026 	case AUDIT_TTY_GET: {
1027 		struct audit_tty_status s;
1028 		struct task_struct *tsk = current;
1029 
1030 		spin_lock(&tsk->sighand->siglock);
1031 		s.enabled = tsk->signal->audit_tty;
1032 		s.log_passwd = tsk->signal->audit_tty_log_passwd;
1033 		spin_unlock(&tsk->sighand->siglock);
1034 
1035 		audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1036 		break;
1037 	}
1038 	case AUDIT_TTY_SET: {
1039 		struct audit_tty_status s, old;
1040 		struct task_struct *tsk = current;
1041 		struct audit_buffer	*ab;
1042 
1043 		memset(&s, 0, sizeof(s));
1044 		/* guard against past and future API changes */
1045 		memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1046 		/* check if new data is valid */
1047 		if ((s.enabled != 0 && s.enabled != 1) ||
1048 		    (s.log_passwd != 0 && s.log_passwd != 1))
1049 			err = -EINVAL;
1050 
1051 		spin_lock(&tsk->sighand->siglock);
1052 		old.enabled = tsk->signal->audit_tty;
1053 		old.log_passwd = tsk->signal->audit_tty_log_passwd;
1054 		if (!err) {
1055 			tsk->signal->audit_tty = s.enabled;
1056 			tsk->signal->audit_tty_log_passwd = s.log_passwd;
1057 		}
1058 		spin_unlock(&tsk->sighand->siglock);
1059 
1060 		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1061 		audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1062 				 " old-log_passwd=%d new-log_passwd=%d res=%d",
1063 				 old.enabled, s.enabled, old.log_passwd,
1064 				 s.log_passwd, !err);
1065 		audit_log_end(ab);
1066 		break;
1067 	}
1068 	default:
1069 		err = -EINVAL;
1070 		break;
1071 	}
1072 
1073 	return err < 0 ? err : 0;
1074 }
1075 
1076 /*
1077  * Get message from skb.  Each message is processed by audit_receive_msg.
1078  * Malformed skbs with wrong length are discarded silently.
1079  */
1080 static void audit_receive_skb(struct sk_buff *skb)
1081 {
1082 	struct nlmsghdr *nlh;
1083 	/*
1084 	 * len MUST be signed for nlmsg_next to be able to dec it below 0
1085 	 * if the nlmsg_len was not aligned
1086 	 */
1087 	int len;
1088 	int err;
1089 
1090 	nlh = nlmsg_hdr(skb);
1091 	len = skb->len;
1092 
1093 	while (nlmsg_ok(nlh, len)) {
1094 		err = audit_receive_msg(skb, nlh);
1095 		/* if err or if this message says it wants a response */
1096 		if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1097 			netlink_ack(skb, nlh, err);
1098 
1099 		nlh = nlmsg_next(nlh, &len);
1100 	}
1101 }
1102 
1103 /* Receive messages from netlink socket. */
1104 static void audit_receive(struct sk_buff  *skb)
1105 {
1106 	mutex_lock(&audit_cmd_mutex);
1107 	audit_receive_skb(skb);
1108 	mutex_unlock(&audit_cmd_mutex);
1109 }
1110 
1111 /* Run custom bind function on netlink socket group connect or bind requests. */
1112 static int audit_bind(int group)
1113 {
1114 	if (!capable(CAP_AUDIT_READ))
1115 		return -EPERM;
1116 
1117 	return 0;
1118 }
1119 
1120 static int __net_init audit_net_init(struct net *net)
1121 {
1122 	struct netlink_kernel_cfg cfg = {
1123 		.input	= audit_receive,
1124 		.bind	= audit_bind,
1125 		.flags	= NL_CFG_F_NONROOT_RECV,
1126 		.groups	= AUDIT_NLGRP_MAX,
1127 	};
1128 
1129 	struct audit_net *aunet = net_generic(net, audit_net_id);
1130 
1131 	aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1132 	if (aunet->nlsk == NULL) {
1133 		audit_panic("cannot initialize netlink socket in namespace");
1134 		return -ENOMEM;
1135 	}
1136 	aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1137 	return 0;
1138 }
1139 
1140 static void __net_exit audit_net_exit(struct net *net)
1141 {
1142 	struct audit_net *aunet = net_generic(net, audit_net_id);
1143 	struct sock *sock = aunet->nlsk;
1144 	if (sock == audit_sock) {
1145 		audit_pid = 0;
1146 		audit_sock = NULL;
1147 	}
1148 
1149 	RCU_INIT_POINTER(aunet->nlsk, NULL);
1150 	synchronize_net();
1151 	netlink_kernel_release(sock);
1152 }
1153 
1154 static struct pernet_operations audit_net_ops __net_initdata = {
1155 	.init = audit_net_init,
1156 	.exit = audit_net_exit,
1157 	.id = &audit_net_id,
1158 	.size = sizeof(struct audit_net),
1159 };
1160 
1161 /* Initialize audit support at boot time. */
1162 static int __init audit_init(void)
1163 {
1164 	int i;
1165 
1166 	if (audit_initialized == AUDIT_DISABLED)
1167 		return 0;
1168 
1169 	pr_info("initializing netlink subsys (%s)\n",
1170 		audit_default ? "enabled" : "disabled");
1171 	register_pernet_subsys(&audit_net_ops);
1172 
1173 	skb_queue_head_init(&audit_skb_queue);
1174 	skb_queue_head_init(&audit_skb_hold_queue);
1175 	audit_initialized = AUDIT_INITIALIZED;
1176 	audit_enabled = audit_default;
1177 	audit_ever_enabled |= !!audit_default;
1178 
1179 	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
1180 
1181 	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1182 		INIT_LIST_HEAD(&audit_inode_hash[i]);
1183 
1184 	return 0;
1185 }
1186 __initcall(audit_init);
1187 
1188 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
1189 static int __init audit_enable(char *str)
1190 {
1191 	audit_default = !!simple_strtol(str, NULL, 0);
1192 	if (!audit_default)
1193 		audit_initialized = AUDIT_DISABLED;
1194 
1195 	pr_info("%s\n", audit_default ?
1196 		"enabled (after initialization)" : "disabled (until reboot)");
1197 
1198 	return 1;
1199 }
1200 __setup("audit=", audit_enable);
1201 
1202 /* Process kernel command-line parameter at boot time.
1203  * audit_backlog_limit=<n> */
1204 static int __init audit_backlog_limit_set(char *str)
1205 {
1206 	u32 audit_backlog_limit_arg;
1207 
1208 	pr_info("audit_backlog_limit: ");
1209 	if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1210 		pr_cont("using default of %u, unable to parse %s\n",
1211 			audit_backlog_limit, str);
1212 		return 1;
1213 	}
1214 
1215 	audit_backlog_limit = audit_backlog_limit_arg;
1216 	pr_cont("%d\n", audit_backlog_limit);
1217 
1218 	return 1;
1219 }
1220 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1221 
1222 static void audit_buffer_free(struct audit_buffer *ab)
1223 {
1224 	unsigned long flags;
1225 
1226 	if (!ab)
1227 		return;
1228 
1229 	if (ab->skb)
1230 		kfree_skb(ab->skb);
1231 
1232 	spin_lock_irqsave(&audit_freelist_lock, flags);
1233 	if (audit_freelist_count > AUDIT_MAXFREE)
1234 		kfree(ab);
1235 	else {
1236 		audit_freelist_count++;
1237 		list_add(&ab->list, &audit_freelist);
1238 	}
1239 	spin_unlock_irqrestore(&audit_freelist_lock, flags);
1240 }
1241 
1242 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1243 						gfp_t gfp_mask, int type)
1244 {
1245 	unsigned long flags;
1246 	struct audit_buffer *ab = NULL;
1247 	struct nlmsghdr *nlh;
1248 
1249 	spin_lock_irqsave(&audit_freelist_lock, flags);
1250 	if (!list_empty(&audit_freelist)) {
1251 		ab = list_entry(audit_freelist.next,
1252 				struct audit_buffer, list);
1253 		list_del(&ab->list);
1254 		--audit_freelist_count;
1255 	}
1256 	spin_unlock_irqrestore(&audit_freelist_lock, flags);
1257 
1258 	if (!ab) {
1259 		ab = kmalloc(sizeof(*ab), gfp_mask);
1260 		if (!ab)
1261 			goto err;
1262 	}
1263 
1264 	ab->ctx = ctx;
1265 	ab->gfp_mask = gfp_mask;
1266 
1267 	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1268 	if (!ab->skb)
1269 		goto err;
1270 
1271 	nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1272 	if (!nlh)
1273 		goto out_kfree_skb;
1274 
1275 	return ab;
1276 
1277 out_kfree_skb:
1278 	kfree_skb(ab->skb);
1279 	ab->skb = NULL;
1280 err:
1281 	audit_buffer_free(ab);
1282 	return NULL;
1283 }
1284 
1285 /**
1286  * audit_serial - compute a serial number for the audit record
1287  *
1288  * Compute a serial number for the audit record.  Audit records are
1289  * written to user-space as soon as they are generated, so a complete
1290  * audit record may be written in several pieces.  The timestamp of the
1291  * record and this serial number are used by the user-space tools to
1292  * determine which pieces belong to the same audit record.  The
1293  * (timestamp,serial) tuple is unique for each syscall and is live from
1294  * syscall entry to syscall exit.
1295  *
1296  * NOTE: Another possibility is to store the formatted records off the
1297  * audit context (for those records that have a context), and emit them
1298  * all at syscall exit.  However, this could delay the reporting of
1299  * significant errors until syscall exit (or never, if the system
1300  * halts).
1301  */
1302 unsigned int audit_serial(void)
1303 {
1304 	static atomic_t serial = ATOMIC_INIT(0);
1305 
1306 	return atomic_add_return(1, &serial);
1307 }
1308 
1309 static inline void audit_get_stamp(struct audit_context *ctx,
1310 				   struct timespec *t, unsigned int *serial)
1311 {
1312 	if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1313 		*t = CURRENT_TIME;
1314 		*serial = audit_serial();
1315 	}
1316 }
1317 
1318 /*
1319  * Wait for auditd to drain the queue a little
1320  */
1321 static long wait_for_auditd(long sleep_time)
1322 {
1323 	DECLARE_WAITQUEUE(wait, current);
1324 	set_current_state(TASK_UNINTERRUPTIBLE);
1325 	add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1326 
1327 	if (audit_backlog_limit &&
1328 	    skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1329 		sleep_time = schedule_timeout(sleep_time);
1330 
1331 	__set_current_state(TASK_RUNNING);
1332 	remove_wait_queue(&audit_backlog_wait, &wait);
1333 
1334 	return sleep_time;
1335 }
1336 
1337 /**
1338  * audit_log_start - obtain an audit buffer
1339  * @ctx: audit_context (may be NULL)
1340  * @gfp_mask: type of allocation
1341  * @type: audit message type
1342  *
1343  * Returns audit_buffer pointer on success or NULL on error.
1344  *
1345  * Obtain an audit buffer.  This routine does locking to obtain the
1346  * audit buffer, but then no locking is required for calls to
1347  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1348  * syscall, then the syscall is marked as auditable and an audit record
1349  * will be written at syscall exit.  If there is no associated task, then
1350  * task context (ctx) should be NULL.
1351  */
1352 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1353 				     int type)
1354 {
1355 	struct audit_buffer	*ab	= NULL;
1356 	struct timespec		t;
1357 	unsigned int		uninitialized_var(serial);
1358 	int reserve = 5; /* Allow atomic callers to go up to five
1359 			    entries over the normal backlog limit */
1360 	unsigned long timeout_start = jiffies;
1361 
1362 	if (audit_initialized != AUDIT_INITIALIZED)
1363 		return NULL;
1364 
1365 	if (unlikely(audit_filter_type(type)))
1366 		return NULL;
1367 
1368 	if (gfp_mask & __GFP_WAIT) {
1369 		if (audit_pid && audit_pid == current->pid)
1370 			gfp_mask &= ~__GFP_WAIT;
1371 		else
1372 			reserve = 0;
1373 	}
1374 
1375 	while (audit_backlog_limit
1376 	       && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1377 		if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
1378 			long sleep_time;
1379 
1380 			sleep_time = timeout_start + audit_backlog_wait_time - jiffies;
1381 			if (sleep_time > 0) {
1382 				sleep_time = wait_for_auditd(sleep_time);
1383 				if (sleep_time > 0)
1384 					continue;
1385 			}
1386 		}
1387 		if (audit_rate_check() && printk_ratelimit())
1388 			pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1389 				skb_queue_len(&audit_skb_queue),
1390 				audit_backlog_limit);
1391 		audit_log_lost("backlog limit exceeded");
1392 		audit_backlog_wait_time = audit_backlog_wait_overflow;
1393 		wake_up(&audit_backlog_wait);
1394 		return NULL;
1395 	}
1396 
1397 	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
1398 
1399 	ab = audit_buffer_alloc(ctx, gfp_mask, type);
1400 	if (!ab) {
1401 		audit_log_lost("out of memory in audit_log_start");
1402 		return NULL;
1403 	}
1404 
1405 	audit_get_stamp(ab->ctx, &t, &serial);
1406 
1407 	audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1408 			 t.tv_sec, t.tv_nsec/1000000, serial);
1409 	return ab;
1410 }
1411 
1412 /**
1413  * audit_expand - expand skb in the audit buffer
1414  * @ab: audit_buffer
1415  * @extra: space to add at tail of the skb
1416  *
1417  * Returns 0 (no space) on failed expansion, or available space if
1418  * successful.
1419  */
1420 static inline int audit_expand(struct audit_buffer *ab, int extra)
1421 {
1422 	struct sk_buff *skb = ab->skb;
1423 	int oldtail = skb_tailroom(skb);
1424 	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1425 	int newtail = skb_tailroom(skb);
1426 
1427 	if (ret < 0) {
1428 		audit_log_lost("out of memory in audit_expand");
1429 		return 0;
1430 	}
1431 
1432 	skb->truesize += newtail - oldtail;
1433 	return newtail;
1434 }
1435 
1436 /*
1437  * Format an audit message into the audit buffer.  If there isn't enough
1438  * room in the audit buffer, more room will be allocated and vsnprint
1439  * will be called a second time.  Currently, we assume that a printk
1440  * can't format message larger than 1024 bytes, so we don't either.
1441  */
1442 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1443 			      va_list args)
1444 {
1445 	int len, avail;
1446 	struct sk_buff *skb;
1447 	va_list args2;
1448 
1449 	if (!ab)
1450 		return;
1451 
1452 	BUG_ON(!ab->skb);
1453 	skb = ab->skb;
1454 	avail = skb_tailroom(skb);
1455 	if (avail == 0) {
1456 		avail = audit_expand(ab, AUDIT_BUFSIZ);
1457 		if (!avail)
1458 			goto out;
1459 	}
1460 	va_copy(args2, args);
1461 	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1462 	if (len >= avail) {
1463 		/* The printk buffer is 1024 bytes long, so if we get
1464 		 * here and AUDIT_BUFSIZ is at least 1024, then we can
1465 		 * log everything that printk could have logged. */
1466 		avail = audit_expand(ab,
1467 			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1468 		if (!avail)
1469 			goto out_va_end;
1470 		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1471 	}
1472 	if (len > 0)
1473 		skb_put(skb, len);
1474 out_va_end:
1475 	va_end(args2);
1476 out:
1477 	return;
1478 }
1479 
1480 /**
1481  * audit_log_format - format a message into the audit buffer.
1482  * @ab: audit_buffer
1483  * @fmt: format string
1484  * @...: optional parameters matching @fmt string
1485  *
1486  * All the work is done in audit_log_vformat.
1487  */
1488 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1489 {
1490 	va_list args;
1491 
1492 	if (!ab)
1493 		return;
1494 	va_start(args, fmt);
1495 	audit_log_vformat(ab, fmt, args);
1496 	va_end(args);
1497 }
1498 
1499 /**
1500  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1501  * @ab: the audit_buffer
1502  * @buf: buffer to convert to hex
1503  * @len: length of @buf to be converted
1504  *
1505  * No return value; failure to expand is silently ignored.
1506  *
1507  * This function will take the passed buf and convert it into a string of
1508  * ascii hex digits. The new string is placed onto the skb.
1509  */
1510 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1511 		size_t len)
1512 {
1513 	int i, avail, new_len;
1514 	unsigned char *ptr;
1515 	struct sk_buff *skb;
1516 
1517 	if (!ab)
1518 		return;
1519 
1520 	BUG_ON(!ab->skb);
1521 	skb = ab->skb;
1522 	avail = skb_tailroom(skb);
1523 	new_len = len<<1;
1524 	if (new_len >= avail) {
1525 		/* Round the buffer request up to the next multiple */
1526 		new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1527 		avail = audit_expand(ab, new_len);
1528 		if (!avail)
1529 			return;
1530 	}
1531 
1532 	ptr = skb_tail_pointer(skb);
1533 	for (i = 0; i < len; i++)
1534 		ptr = hex_byte_pack_upper(ptr, buf[i]);
1535 	*ptr = 0;
1536 	skb_put(skb, len << 1); /* new string is twice the old string */
1537 }
1538 
1539 /*
1540  * Format a string of no more than slen characters into the audit buffer,
1541  * enclosed in quote marks.
1542  */
1543 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1544 			size_t slen)
1545 {
1546 	int avail, new_len;
1547 	unsigned char *ptr;
1548 	struct sk_buff *skb;
1549 
1550 	if (!ab)
1551 		return;
1552 
1553 	BUG_ON(!ab->skb);
1554 	skb = ab->skb;
1555 	avail = skb_tailroom(skb);
1556 	new_len = slen + 3;	/* enclosing quotes + null terminator */
1557 	if (new_len > avail) {
1558 		avail = audit_expand(ab, new_len);
1559 		if (!avail)
1560 			return;
1561 	}
1562 	ptr = skb_tail_pointer(skb);
1563 	*ptr++ = '"';
1564 	memcpy(ptr, string, slen);
1565 	ptr += slen;
1566 	*ptr++ = '"';
1567 	*ptr = 0;
1568 	skb_put(skb, slen + 2);	/* don't include null terminator */
1569 }
1570 
1571 /**
1572  * audit_string_contains_control - does a string need to be logged in hex
1573  * @string: string to be checked
1574  * @len: max length of the string to check
1575  */
1576 int audit_string_contains_control(const char *string, size_t len)
1577 {
1578 	const unsigned char *p;
1579 	for (p = string; p < (const unsigned char *)string + len; p++) {
1580 		if (*p == '"' || *p < 0x21 || *p > 0x7e)
1581 			return 1;
1582 	}
1583 	return 0;
1584 }
1585 
1586 /**
1587  * audit_log_n_untrustedstring - log a string that may contain random characters
1588  * @ab: audit_buffer
1589  * @len: length of string (not including trailing null)
1590  * @string: string to be logged
1591  *
1592  * This code will escape a string that is passed to it if the string
1593  * contains a control character, unprintable character, double quote mark,
1594  * or a space. Unescaped strings will start and end with a double quote mark.
1595  * Strings that are escaped are printed in hex (2 digits per char).
1596  *
1597  * The caller specifies the number of characters in the string to log, which may
1598  * or may not be the entire string.
1599  */
1600 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1601 				 size_t len)
1602 {
1603 	if (audit_string_contains_control(string, len))
1604 		audit_log_n_hex(ab, string, len);
1605 	else
1606 		audit_log_n_string(ab, string, len);
1607 }
1608 
1609 /**
1610  * audit_log_untrustedstring - log a string that may contain random characters
1611  * @ab: audit_buffer
1612  * @string: string to be logged
1613  *
1614  * Same as audit_log_n_untrustedstring(), except that strlen is used to
1615  * determine string length.
1616  */
1617 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1618 {
1619 	audit_log_n_untrustedstring(ab, string, strlen(string));
1620 }
1621 
1622 /* This is a helper-function to print the escaped d_path */
1623 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1624 		      const struct path *path)
1625 {
1626 	char *p, *pathname;
1627 
1628 	if (prefix)
1629 		audit_log_format(ab, "%s", prefix);
1630 
1631 	/* We will allow 11 spaces for ' (deleted)' to be appended */
1632 	pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1633 	if (!pathname) {
1634 		audit_log_string(ab, "<no_memory>");
1635 		return;
1636 	}
1637 	p = d_path(path, pathname, PATH_MAX+11);
1638 	if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1639 		/* FIXME: can we save some information here? */
1640 		audit_log_string(ab, "<too_long>");
1641 	} else
1642 		audit_log_untrustedstring(ab, p);
1643 	kfree(pathname);
1644 }
1645 
1646 void audit_log_session_info(struct audit_buffer *ab)
1647 {
1648 	unsigned int sessionid = audit_get_sessionid(current);
1649 	uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1650 
1651 	audit_log_format(ab, " auid=%u ses=%u", auid, sessionid);
1652 }
1653 
1654 void audit_log_key(struct audit_buffer *ab, char *key)
1655 {
1656 	audit_log_format(ab, " key=");
1657 	if (key)
1658 		audit_log_untrustedstring(ab, key);
1659 	else
1660 		audit_log_format(ab, "(null)");
1661 }
1662 
1663 void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1664 {
1665 	int i;
1666 
1667 	audit_log_format(ab, " %s=", prefix);
1668 	CAP_FOR_EACH_U32(i) {
1669 		audit_log_format(ab, "%08x",
1670 				 cap->cap[CAP_LAST_U32 - i]);
1671 	}
1672 }
1673 
1674 static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1675 {
1676 	kernel_cap_t *perm = &name->fcap.permitted;
1677 	kernel_cap_t *inh = &name->fcap.inheritable;
1678 	int log = 0;
1679 
1680 	if (!cap_isclear(*perm)) {
1681 		audit_log_cap(ab, "cap_fp", perm);
1682 		log = 1;
1683 	}
1684 	if (!cap_isclear(*inh)) {
1685 		audit_log_cap(ab, "cap_fi", inh);
1686 		log = 1;
1687 	}
1688 
1689 	if (log)
1690 		audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1691 				 name->fcap.fE, name->fcap_ver);
1692 }
1693 
1694 static inline int audit_copy_fcaps(struct audit_names *name,
1695 				   const struct dentry *dentry)
1696 {
1697 	struct cpu_vfs_cap_data caps;
1698 	int rc;
1699 
1700 	if (!dentry)
1701 		return 0;
1702 
1703 	rc = get_vfs_caps_from_disk(dentry, &caps);
1704 	if (rc)
1705 		return rc;
1706 
1707 	name->fcap.permitted = caps.permitted;
1708 	name->fcap.inheritable = caps.inheritable;
1709 	name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1710 	name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1711 				VFS_CAP_REVISION_SHIFT;
1712 
1713 	return 0;
1714 }
1715 
1716 /* Copy inode data into an audit_names. */
1717 void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1718 		      const struct inode *inode)
1719 {
1720 	name->ino   = inode->i_ino;
1721 	name->dev   = inode->i_sb->s_dev;
1722 	name->mode  = inode->i_mode;
1723 	name->uid   = inode->i_uid;
1724 	name->gid   = inode->i_gid;
1725 	name->rdev  = inode->i_rdev;
1726 	security_inode_getsecid(inode, &name->osid);
1727 	audit_copy_fcaps(name, dentry);
1728 }
1729 
1730 /**
1731  * audit_log_name - produce AUDIT_PATH record from struct audit_names
1732  * @context: audit_context for the task
1733  * @n: audit_names structure with reportable details
1734  * @path: optional path to report instead of audit_names->name
1735  * @record_num: record number to report when handling a list of names
1736  * @call_panic: optional pointer to int that will be updated if secid fails
1737  */
1738 void audit_log_name(struct audit_context *context, struct audit_names *n,
1739 		    struct path *path, int record_num, int *call_panic)
1740 {
1741 	struct audit_buffer *ab;
1742 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1743 	if (!ab)
1744 		return;
1745 
1746 	audit_log_format(ab, "item=%d", record_num);
1747 
1748 	if (path)
1749 		audit_log_d_path(ab, " name=", path);
1750 	else if (n->name) {
1751 		switch (n->name_len) {
1752 		case AUDIT_NAME_FULL:
1753 			/* log the full path */
1754 			audit_log_format(ab, " name=");
1755 			audit_log_untrustedstring(ab, n->name->name);
1756 			break;
1757 		case 0:
1758 			/* name was specified as a relative path and the
1759 			 * directory component is the cwd */
1760 			audit_log_d_path(ab, " name=", &context->pwd);
1761 			break;
1762 		default:
1763 			/* log the name's directory component */
1764 			audit_log_format(ab, " name=");
1765 			audit_log_n_untrustedstring(ab, n->name->name,
1766 						    n->name_len);
1767 		}
1768 	} else
1769 		audit_log_format(ab, " name=(null)");
1770 
1771 	if (n->ino != (unsigned long)-1) {
1772 		audit_log_format(ab, " inode=%lu"
1773 				 " dev=%02x:%02x mode=%#ho"
1774 				 " ouid=%u ogid=%u rdev=%02x:%02x",
1775 				 n->ino,
1776 				 MAJOR(n->dev),
1777 				 MINOR(n->dev),
1778 				 n->mode,
1779 				 from_kuid(&init_user_ns, n->uid),
1780 				 from_kgid(&init_user_ns, n->gid),
1781 				 MAJOR(n->rdev),
1782 				 MINOR(n->rdev));
1783 	}
1784 	if (n->osid != 0) {
1785 		char *ctx = NULL;
1786 		u32 len;
1787 		if (security_secid_to_secctx(
1788 			n->osid, &ctx, &len)) {
1789 			audit_log_format(ab, " osid=%u", n->osid);
1790 			if (call_panic)
1791 				*call_panic = 2;
1792 		} else {
1793 			audit_log_format(ab, " obj=%s", ctx);
1794 			security_release_secctx(ctx, len);
1795 		}
1796 	}
1797 
1798 	/* log the audit_names record type */
1799 	audit_log_format(ab, " nametype=");
1800 	switch(n->type) {
1801 	case AUDIT_TYPE_NORMAL:
1802 		audit_log_format(ab, "NORMAL");
1803 		break;
1804 	case AUDIT_TYPE_PARENT:
1805 		audit_log_format(ab, "PARENT");
1806 		break;
1807 	case AUDIT_TYPE_CHILD_DELETE:
1808 		audit_log_format(ab, "DELETE");
1809 		break;
1810 	case AUDIT_TYPE_CHILD_CREATE:
1811 		audit_log_format(ab, "CREATE");
1812 		break;
1813 	default:
1814 		audit_log_format(ab, "UNKNOWN");
1815 		break;
1816 	}
1817 
1818 	audit_log_fcaps(ab, n);
1819 	audit_log_end(ab);
1820 }
1821 
1822 int audit_log_task_context(struct audit_buffer *ab)
1823 {
1824 	char *ctx = NULL;
1825 	unsigned len;
1826 	int error;
1827 	u32 sid;
1828 
1829 	security_task_getsecid(current, &sid);
1830 	if (!sid)
1831 		return 0;
1832 
1833 	error = security_secid_to_secctx(sid, &ctx, &len);
1834 	if (error) {
1835 		if (error != -EINVAL)
1836 			goto error_path;
1837 		return 0;
1838 	}
1839 
1840 	audit_log_format(ab, " subj=%s", ctx);
1841 	security_release_secctx(ctx, len);
1842 	return 0;
1843 
1844 error_path:
1845 	audit_panic("error in audit_log_task_context");
1846 	return error;
1847 }
1848 EXPORT_SYMBOL(audit_log_task_context);
1849 
1850 void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
1851 {
1852 	const struct cred *cred;
1853 	char comm[sizeof(tsk->comm)];
1854 	struct mm_struct *mm = tsk->mm;
1855 	char *tty;
1856 
1857 	if (!ab)
1858 		return;
1859 
1860 	/* tsk == current */
1861 	cred = current_cred();
1862 
1863 	spin_lock_irq(&tsk->sighand->siglock);
1864 	if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
1865 		tty = tsk->signal->tty->name;
1866 	else
1867 		tty = "(none)";
1868 	spin_unlock_irq(&tsk->sighand->siglock);
1869 
1870 	audit_log_format(ab,
1871 			 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
1872 			 " euid=%u suid=%u fsuid=%u"
1873 			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
1874 			 task_ppid_nr(tsk),
1875 			 task_pid_nr(tsk),
1876 			 from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
1877 			 from_kuid(&init_user_ns, cred->uid),
1878 			 from_kgid(&init_user_ns, cred->gid),
1879 			 from_kuid(&init_user_ns, cred->euid),
1880 			 from_kuid(&init_user_ns, cred->suid),
1881 			 from_kuid(&init_user_ns, cred->fsuid),
1882 			 from_kgid(&init_user_ns, cred->egid),
1883 			 from_kgid(&init_user_ns, cred->sgid),
1884 			 from_kgid(&init_user_ns, cred->fsgid),
1885 			 tty, audit_get_sessionid(tsk));
1886 
1887 	audit_log_format(ab, " comm=");
1888 	audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
1889 
1890 	if (mm) {
1891 		down_read(&mm->mmap_sem);
1892 		if (mm->exe_file)
1893 			audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
1894 		up_read(&mm->mmap_sem);
1895 	} else
1896 		audit_log_format(ab, " exe=(null)");
1897 	audit_log_task_context(ab);
1898 }
1899 EXPORT_SYMBOL(audit_log_task_info);
1900 
1901 /**
1902  * audit_log_link_denied - report a link restriction denial
1903  * @operation: specific link opreation
1904  * @link: the path that triggered the restriction
1905  */
1906 void audit_log_link_denied(const char *operation, struct path *link)
1907 {
1908 	struct audit_buffer *ab;
1909 	struct audit_names *name;
1910 
1911 	name = kzalloc(sizeof(*name), GFP_NOFS);
1912 	if (!name)
1913 		return;
1914 
1915 	/* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
1916 	ab = audit_log_start(current->audit_context, GFP_KERNEL,
1917 			     AUDIT_ANOM_LINK);
1918 	if (!ab)
1919 		goto out;
1920 	audit_log_format(ab, "op=%s", operation);
1921 	audit_log_task_info(ab, current);
1922 	audit_log_format(ab, " res=0");
1923 	audit_log_end(ab);
1924 
1925 	/* Generate AUDIT_PATH record with object. */
1926 	name->type = AUDIT_TYPE_NORMAL;
1927 	audit_copy_inode(name, link->dentry, link->dentry->d_inode);
1928 	audit_log_name(current->audit_context, name, link, 0, NULL);
1929 out:
1930 	kfree(name);
1931 }
1932 
1933 /**
1934  * audit_log_end - end one audit record
1935  * @ab: the audit_buffer
1936  *
1937  * netlink_unicast() cannot be called inside an irq context because it blocks
1938  * (last arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed
1939  * on a queue and a tasklet is scheduled to remove them from the queue outside
1940  * the irq context.  May be called in any context.
1941  */
1942 void audit_log_end(struct audit_buffer *ab)
1943 {
1944 	if (!ab)
1945 		return;
1946 	if (!audit_rate_check()) {
1947 		audit_log_lost("rate limit exceeded");
1948 	} else {
1949 		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1950 
1951 		nlh->nlmsg_len = ab->skb->len;
1952 		kauditd_send_multicast_skb(ab->skb);
1953 
1954 		/*
1955 		 * The original kaudit unicast socket sends up messages with
1956 		 * nlmsg_len set to the payload length rather than the entire
1957 		 * message length.  This breaks the standard set by netlink.
1958 		 * The existing auditd daemon assumes this breakage.  Fixing
1959 		 * this would require co-ordinating a change in the established
1960 		 * protocol between the kaudit kernel subsystem and the auditd
1961 		 * userspace code.
1962 		 */
1963 		nlh->nlmsg_len -= NLMSG_HDRLEN;
1964 
1965 		if (audit_pid) {
1966 			skb_queue_tail(&audit_skb_queue, ab->skb);
1967 			wake_up_interruptible(&kauditd_wait);
1968 		} else {
1969 			audit_printk_skb(ab->skb);
1970 		}
1971 		ab->skb = NULL;
1972 	}
1973 	audit_buffer_free(ab);
1974 }
1975 
1976 /**
1977  * audit_log - Log an audit record
1978  * @ctx: audit context
1979  * @gfp_mask: type of allocation
1980  * @type: audit message type
1981  * @fmt: format string to use
1982  * @...: variable parameters matching the format string
1983  *
1984  * This is a convenience function that calls audit_log_start,
1985  * audit_log_vformat, and audit_log_end.  It may be called
1986  * in any context.
1987  */
1988 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1989 	       const char *fmt, ...)
1990 {
1991 	struct audit_buffer *ab;
1992 	va_list args;
1993 
1994 	ab = audit_log_start(ctx, gfp_mask, type);
1995 	if (ab) {
1996 		va_start(args, fmt);
1997 		audit_log_vformat(ab, fmt, args);
1998 		va_end(args);
1999 		audit_log_end(ab);
2000 	}
2001 }
2002 
2003 #ifdef CONFIG_SECURITY
2004 /**
2005  * audit_log_secctx - Converts and logs SELinux context
2006  * @ab: audit_buffer
2007  * @secid: security number
2008  *
2009  * This is a helper function that calls security_secid_to_secctx to convert
2010  * secid to secctx and then adds the (converted) SELinux context to the audit
2011  * log by calling audit_log_format, thus also preventing leak of internal secid
2012  * to userspace. If secid cannot be converted audit_panic is called.
2013  */
2014 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
2015 {
2016 	u32 len;
2017 	char *secctx;
2018 
2019 	if (security_secid_to_secctx(secid, &secctx, &len)) {
2020 		audit_panic("Cannot convert secid to context");
2021 	} else {
2022 		audit_log_format(ab, " obj=%s", secctx);
2023 		security_release_secctx(secctx, len);
2024 	}
2025 }
2026 EXPORT_SYMBOL(audit_log_secctx);
2027 #endif
2028 
2029 EXPORT_SYMBOL(audit_log_start);
2030 EXPORT_SYMBOL(audit_log_end);
2031 EXPORT_SYMBOL(audit_log_format);
2032 EXPORT_SYMBOL(audit_log);
2033