xref: /openbmc/linux/kernel/audit.c (revision b6dcefde)
1 /* audit.c -- Auditing support
2  * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
3  * System-call specific features have moved to auditsc.c
4  *
5  * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
6  * All Rights Reserved.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21  *
22  * Written by Rickard E. (Rik) Faith <faith@redhat.com>
23  *
24  * Goals: 1) Integrate fully with Security Modules.
25  *	  2) Minimal run-time overhead:
26  *	     a) Minimal when syscall auditing is disabled (audit_enable=0).
27  *	     b) Small when syscall auditing is enabled and no audit record
28  *		is generated (defer as much work as possible to record
29  *		generation time):
30  *		i) context is allocated,
31  *		ii) names from getname are stored without a copy, and
32  *		iii) inode information stored from path_lookup.
33  *	  3) Ability to disable syscall auditing at boot time (audit=0).
34  *	  4) Usable by other parts of the kernel (if audit_log* is called,
35  *	     then a syscall record will be generated automatically for the
36  *	     current syscall).
37  *	  5) Netlink interface to user-space.
38  *	  6) Support low-overhead kernel-based filtering to minimize the
39  *	     information that must be passed to user-space.
40  *
41  * Example user-space utilities: http://people.redhat.com/sgrubb/audit/
42  */
43 
44 #include <linux/init.h>
45 #include <asm/types.h>
46 #include <asm/atomic.h>
47 #include <linux/mm.h>
48 #include <linux/module.h>
49 #include <linux/err.h>
50 #include <linux/kthread.h>
51 
52 #include <linux/audit.h>
53 
54 #include <net/sock.h>
55 #include <net/netlink.h>
56 #include <linux/skbuff.h>
57 #include <linux/netlink.h>
58 #include <linux/inotify.h>
59 #include <linux/freezer.h>
60 #include <linux/tty.h>
61 
62 #include "audit.h"
63 
64 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
65  * (Initialization happens after skb_init is called.) */
66 #define AUDIT_DISABLED		-1
67 #define AUDIT_UNINITIALIZED	0
68 #define AUDIT_INITIALIZED	1
69 static int	audit_initialized;
70 
71 #define AUDIT_OFF	0
72 #define AUDIT_ON	1
73 #define AUDIT_LOCKED	2
74 int		audit_enabled;
75 int		audit_ever_enabled;
76 
77 /* Default state when kernel boots without any parameters. */
78 static int	audit_default;
79 
80 /* If auditing cannot proceed, audit_failure selects what happens. */
81 static int	audit_failure = AUDIT_FAIL_PRINTK;
82 
83 /*
84  * If audit records are to be written to the netlink socket, audit_pid
85  * contains the pid of the auditd process and audit_nlk_pid contains
86  * the pid to use to send netlink messages to that process.
87  */
88 int		audit_pid;
89 static int	audit_nlk_pid;
90 
91 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
92  * to that number per second.  This prevents DoS attacks, but results in
93  * audit records being dropped. */
94 static int	audit_rate_limit;
95 
96 /* Number of outstanding audit_buffers allowed. */
97 static int	audit_backlog_limit = 64;
98 static int	audit_backlog_wait_time = 60 * HZ;
99 static int	audit_backlog_wait_overflow = 0;
100 
101 /* The identity of the user shutting down the audit system. */
102 uid_t		audit_sig_uid = -1;
103 pid_t		audit_sig_pid = -1;
104 u32		audit_sig_sid = 0;
105 
106 /* Records can be lost in several ways:
107    0) [suppressed in audit_alloc]
108    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
109    2) out of memory in audit_log_move [alloc_skb]
110    3) suppressed due to audit_rate_limit
111    4) suppressed due to audit_backlog_limit
112 */
113 static atomic_t    audit_lost = ATOMIC_INIT(0);
114 
115 /* The netlink socket. */
116 static struct sock *audit_sock;
117 
118 /* Hash for inode-based rules */
119 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
120 
121 /* The audit_freelist is a list of pre-allocated audit buffers (if more
122  * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
123  * being placed on the freelist). */
124 static DEFINE_SPINLOCK(audit_freelist_lock);
125 static int	   audit_freelist_count;
126 static LIST_HEAD(audit_freelist);
127 
128 static struct sk_buff_head audit_skb_queue;
129 /* queue of skbs to send to auditd when/if it comes back */
130 static struct sk_buff_head audit_skb_hold_queue;
131 static struct task_struct *kauditd_task;
132 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
133 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
134 
135 /* Serialize requests from userspace. */
136 DEFINE_MUTEX(audit_cmd_mutex);
137 
138 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
139  * audit records.  Since printk uses a 1024 byte buffer, this buffer
140  * should be at least that large. */
141 #define AUDIT_BUFSIZ 1024
142 
143 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
144  * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
145 #define AUDIT_MAXFREE  (2*NR_CPUS)
146 
147 /* The audit_buffer is used when formatting an audit record.  The caller
148  * locks briefly to get the record off the freelist or to allocate the
149  * buffer, and locks briefly to send the buffer to the netlink layer or
150  * to place it on a transmit queue.  Multiple audit_buffers can be in
151  * use simultaneously. */
152 struct audit_buffer {
153 	struct list_head     list;
154 	struct sk_buff       *skb;	/* formatted skb ready to send */
155 	struct audit_context *ctx;	/* NULL or associated context */
156 	gfp_t		     gfp_mask;
157 };
158 
159 struct audit_reply {
160 	int pid;
161 	struct sk_buff *skb;
162 };
163 
164 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
165 {
166 	if (ab) {
167 		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
168 		nlh->nlmsg_pid = pid;
169 	}
170 }
171 
172 void audit_panic(const char *message)
173 {
174 	switch (audit_failure)
175 	{
176 	case AUDIT_FAIL_SILENT:
177 		break;
178 	case AUDIT_FAIL_PRINTK:
179 		if (printk_ratelimit())
180 			printk(KERN_ERR "audit: %s\n", message);
181 		break;
182 	case AUDIT_FAIL_PANIC:
183 		/* test audit_pid since printk is always losey, why bother? */
184 		if (audit_pid)
185 			panic("audit: %s\n", message);
186 		break;
187 	}
188 }
189 
190 static inline int audit_rate_check(void)
191 {
192 	static unsigned long	last_check = 0;
193 	static int		messages   = 0;
194 	static DEFINE_SPINLOCK(lock);
195 	unsigned long		flags;
196 	unsigned long		now;
197 	unsigned long		elapsed;
198 	int			retval	   = 0;
199 
200 	if (!audit_rate_limit) return 1;
201 
202 	spin_lock_irqsave(&lock, flags);
203 	if (++messages < audit_rate_limit) {
204 		retval = 1;
205 	} else {
206 		now     = jiffies;
207 		elapsed = now - last_check;
208 		if (elapsed > HZ) {
209 			last_check = now;
210 			messages   = 0;
211 			retval     = 1;
212 		}
213 	}
214 	spin_unlock_irqrestore(&lock, flags);
215 
216 	return retval;
217 }
218 
219 /**
220  * audit_log_lost - conditionally log lost audit message event
221  * @message: the message stating reason for lost audit message
222  *
223  * Emit at least 1 message per second, even if audit_rate_check is
224  * throttling.
225  * Always increment the lost messages counter.
226 */
227 void audit_log_lost(const char *message)
228 {
229 	static unsigned long	last_msg = 0;
230 	static DEFINE_SPINLOCK(lock);
231 	unsigned long		flags;
232 	unsigned long		now;
233 	int			print;
234 
235 	atomic_inc(&audit_lost);
236 
237 	print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
238 
239 	if (!print) {
240 		spin_lock_irqsave(&lock, flags);
241 		now = jiffies;
242 		if (now - last_msg > HZ) {
243 			print = 1;
244 			last_msg = now;
245 		}
246 		spin_unlock_irqrestore(&lock, flags);
247 	}
248 
249 	if (print) {
250 		if (printk_ratelimit())
251 			printk(KERN_WARNING
252 				"audit: audit_lost=%d audit_rate_limit=%d "
253 				"audit_backlog_limit=%d\n",
254 				atomic_read(&audit_lost),
255 				audit_rate_limit,
256 				audit_backlog_limit);
257 		audit_panic(message);
258 	}
259 }
260 
261 static int audit_log_config_change(char *function_name, int new, int old,
262 				   uid_t loginuid, u32 sessionid, u32 sid,
263 				   int allow_changes)
264 {
265 	struct audit_buffer *ab;
266 	int rc = 0;
267 
268 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
269 	audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
270 			 old, loginuid, sessionid);
271 	if (sid) {
272 		char *ctx = NULL;
273 		u32 len;
274 
275 		rc = security_secid_to_secctx(sid, &ctx, &len);
276 		if (rc) {
277 			audit_log_format(ab, " sid=%u", sid);
278 			allow_changes = 0; /* Something weird, deny request */
279 		} else {
280 			audit_log_format(ab, " subj=%s", ctx);
281 			security_release_secctx(ctx, len);
282 		}
283 	}
284 	audit_log_format(ab, " res=%d", allow_changes);
285 	audit_log_end(ab);
286 	return rc;
287 }
288 
289 static int audit_do_config_change(char *function_name, int *to_change,
290 				  int new, uid_t loginuid, u32 sessionid,
291 				  u32 sid)
292 {
293 	int allow_changes, rc = 0, old = *to_change;
294 
295 	/* check if we are locked */
296 	if (audit_enabled == AUDIT_LOCKED)
297 		allow_changes = 0;
298 	else
299 		allow_changes = 1;
300 
301 	if (audit_enabled != AUDIT_OFF) {
302 		rc = audit_log_config_change(function_name, new, old, loginuid,
303 					     sessionid, sid, allow_changes);
304 		if (rc)
305 			allow_changes = 0;
306 	}
307 
308 	/* If we are allowed, make the change */
309 	if (allow_changes == 1)
310 		*to_change = new;
311 	/* Not allowed, update reason */
312 	else if (rc == 0)
313 		rc = -EPERM;
314 	return rc;
315 }
316 
317 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
318 				u32 sid)
319 {
320 	return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
321 				      limit, loginuid, sessionid, sid);
322 }
323 
324 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
325 				   u32 sid)
326 {
327 	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
328 				      limit, loginuid, sessionid, sid);
329 }
330 
331 static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
332 {
333 	int rc;
334 	if (state < AUDIT_OFF || state > AUDIT_LOCKED)
335 		return -EINVAL;
336 
337 	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state,
338 				     loginuid, sessionid, sid);
339 
340 	if (!rc)
341 		audit_ever_enabled |= !!state;
342 
343 	return rc;
344 }
345 
346 static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
347 {
348 	if (state != AUDIT_FAIL_SILENT
349 	    && state != AUDIT_FAIL_PRINTK
350 	    && state != AUDIT_FAIL_PANIC)
351 		return -EINVAL;
352 
353 	return audit_do_config_change("audit_failure", &audit_failure, state,
354 				      loginuid, sessionid, sid);
355 }
356 
357 /*
358  * Queue skbs to be sent to auditd when/if it comes back.  These skbs should
359  * already have been sent via prink/syslog and so if these messages are dropped
360  * it is not a huge concern since we already passed the audit_log_lost()
361  * notification and stuff.  This is just nice to get audit messages during
362  * boot before auditd is running or messages generated while auditd is stopped.
363  * This only holds messages is audit_default is set, aka booting with audit=1
364  * or building your kernel that way.
365  */
366 static void audit_hold_skb(struct sk_buff *skb)
367 {
368 	if (audit_default &&
369 	    skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
370 		skb_queue_tail(&audit_skb_hold_queue, skb);
371 	else
372 		kfree_skb(skb);
373 }
374 
375 /*
376  * For one reason or another this nlh isn't getting delivered to the userspace
377  * audit daemon, just send it to printk.
378  */
379 static void audit_printk_skb(struct sk_buff *skb)
380 {
381 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
382 	char *data = NLMSG_DATA(nlh);
383 
384 	if (nlh->nlmsg_type != AUDIT_EOE) {
385 		if (printk_ratelimit())
386 			printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
387 		else
388 			audit_log_lost("printk limit exceeded\n");
389 	}
390 
391 	audit_hold_skb(skb);
392 }
393 
394 static void kauditd_send_skb(struct sk_buff *skb)
395 {
396 	int err;
397 	/* take a reference in case we can't send it and we want to hold it */
398 	skb_get(skb);
399 	err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
400 	if (err < 0) {
401 		BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
402 		printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
403 		audit_log_lost("auditd dissapeared\n");
404 		audit_pid = 0;
405 		/* we might get lucky and get this in the next auditd */
406 		audit_hold_skb(skb);
407 	} else
408 		/* drop the extra reference if sent ok */
409 		kfree_skb(skb);
410 }
411 
412 static int kauditd_thread(void *dummy)
413 {
414 	struct sk_buff *skb;
415 
416 	set_freezable();
417 	while (!kthread_should_stop()) {
418 		/*
419 		 * if auditd just started drain the queue of messages already
420 		 * sent to syslog/printk.  remember loss here is ok.  we already
421 		 * called audit_log_lost() if it didn't go out normally.  so the
422 		 * race between the skb_dequeue and the next check for audit_pid
423 		 * doesn't matter.
424 		 *
425 		 * if you ever find kauditd to be too slow we can get a perf win
426 		 * by doing our own locking and keeping better track if there
427 		 * are messages in this queue.  I don't see the need now, but
428 		 * in 5 years when I want to play with this again I'll see this
429 		 * note and still have no friggin idea what i'm thinking today.
430 		 */
431 		if (audit_default && audit_pid) {
432 			skb = skb_dequeue(&audit_skb_hold_queue);
433 			if (unlikely(skb)) {
434 				while (skb && audit_pid) {
435 					kauditd_send_skb(skb);
436 					skb = skb_dequeue(&audit_skb_hold_queue);
437 				}
438 			}
439 		}
440 
441 		skb = skb_dequeue(&audit_skb_queue);
442 		wake_up(&audit_backlog_wait);
443 		if (skb) {
444 			if (audit_pid)
445 				kauditd_send_skb(skb);
446 			else
447 				audit_printk_skb(skb);
448 		} else {
449 			DECLARE_WAITQUEUE(wait, current);
450 			set_current_state(TASK_INTERRUPTIBLE);
451 			add_wait_queue(&kauditd_wait, &wait);
452 
453 			if (!skb_queue_len(&audit_skb_queue)) {
454 				try_to_freeze();
455 				schedule();
456 			}
457 
458 			__set_current_state(TASK_RUNNING);
459 			remove_wait_queue(&kauditd_wait, &wait);
460 		}
461 	}
462 	return 0;
463 }
464 
465 static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
466 {
467 	struct task_struct *tsk;
468 	int err;
469 
470 	read_lock(&tasklist_lock);
471 	tsk = find_task_by_vpid(pid);
472 	err = -ESRCH;
473 	if (!tsk)
474 		goto out;
475 	err = 0;
476 
477 	spin_lock_irq(&tsk->sighand->siglock);
478 	if (!tsk->signal->audit_tty)
479 		err = -EPERM;
480 	spin_unlock_irq(&tsk->sighand->siglock);
481 	if (err)
482 		goto out;
483 
484 	tty_audit_push_task(tsk, loginuid, sessionid);
485 out:
486 	read_unlock(&tasklist_lock);
487 	return err;
488 }
489 
490 int audit_send_list(void *_dest)
491 {
492 	struct audit_netlink_list *dest = _dest;
493 	int pid = dest->pid;
494 	struct sk_buff *skb;
495 
496 	/* wait for parent to finish and send an ACK */
497 	mutex_lock(&audit_cmd_mutex);
498 	mutex_unlock(&audit_cmd_mutex);
499 
500 	while ((skb = __skb_dequeue(&dest->q)) != NULL)
501 		netlink_unicast(audit_sock, skb, pid, 0);
502 
503 	kfree(dest);
504 
505 	return 0;
506 }
507 
508 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
509 				 int multi, void *payload, int size)
510 {
511 	struct sk_buff	*skb;
512 	struct nlmsghdr	*nlh;
513 	void		*data;
514 	int		flags = multi ? NLM_F_MULTI : 0;
515 	int		t     = done  ? NLMSG_DONE  : type;
516 
517 	skb = nlmsg_new(size, GFP_KERNEL);
518 	if (!skb)
519 		return NULL;
520 
521 	nlh	= NLMSG_NEW(skb, pid, seq, t, size, flags);
522 	data	= NLMSG_DATA(nlh);
523 	memcpy(data, payload, size);
524 	return skb;
525 
526 nlmsg_failure:			/* Used by NLMSG_NEW */
527 	if (skb)
528 		kfree_skb(skb);
529 	return NULL;
530 }
531 
532 static int audit_send_reply_thread(void *arg)
533 {
534 	struct audit_reply *reply = (struct audit_reply *)arg;
535 
536 	mutex_lock(&audit_cmd_mutex);
537 	mutex_unlock(&audit_cmd_mutex);
538 
539 	/* Ignore failure. It'll only happen if the sender goes away,
540 	   because our timeout is set to infinite. */
541 	netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
542 	kfree(reply);
543 	return 0;
544 }
545 /**
546  * audit_send_reply - send an audit reply message via netlink
547  * @pid: process id to send reply to
548  * @seq: sequence number
549  * @type: audit message type
550  * @done: done (last) flag
551  * @multi: multi-part message flag
552  * @payload: payload data
553  * @size: payload size
554  *
555  * Allocates an skb, builds the netlink message, and sends it to the pid.
556  * No failure notifications.
557  */
558 void audit_send_reply(int pid, int seq, int type, int done, int multi,
559 		      void *payload, int size)
560 {
561 	struct sk_buff *skb;
562 	struct task_struct *tsk;
563 	struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
564 					    GFP_KERNEL);
565 
566 	if (!reply)
567 		return;
568 
569 	skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
570 	if (!skb)
571 		goto out;
572 
573 	reply->pid = pid;
574 	reply->skb = skb;
575 
576 	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
577 	if (!IS_ERR(tsk))
578 		return;
579 	kfree_skb(skb);
580 out:
581 	kfree(reply);
582 }
583 
584 /*
585  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
586  * control messages.
587  */
588 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
589 {
590 	int err = 0;
591 
592 	switch (msg_type) {
593 	case AUDIT_GET:
594 	case AUDIT_LIST:
595 	case AUDIT_LIST_RULES:
596 	case AUDIT_SET:
597 	case AUDIT_ADD:
598 	case AUDIT_ADD_RULE:
599 	case AUDIT_DEL:
600 	case AUDIT_DEL_RULE:
601 	case AUDIT_SIGNAL_INFO:
602 	case AUDIT_TTY_GET:
603 	case AUDIT_TTY_SET:
604 	case AUDIT_TRIM:
605 	case AUDIT_MAKE_EQUIV:
606 		if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
607 			err = -EPERM;
608 		break;
609 	case AUDIT_USER:
610 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
611 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
612 		if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
613 			err = -EPERM;
614 		break;
615 	default:  /* bad msg */
616 		err = -EINVAL;
617 	}
618 
619 	return err;
620 }
621 
622 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
623 				     u32 pid, u32 uid, uid_t auid, u32 ses,
624 				     u32 sid)
625 {
626 	int rc = 0;
627 	char *ctx = NULL;
628 	u32 len;
629 
630 	if (!audit_enabled) {
631 		*ab = NULL;
632 		return rc;
633 	}
634 
635 	*ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
636 	audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u",
637 			 pid, uid, auid, ses);
638 	if (sid) {
639 		rc = security_secid_to_secctx(sid, &ctx, &len);
640 		if (rc)
641 			audit_log_format(*ab, " ssid=%u", sid);
642 		else {
643 			audit_log_format(*ab, " subj=%s", ctx);
644 			security_release_secctx(ctx, len);
645 		}
646 	}
647 
648 	return rc;
649 }
650 
651 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
652 {
653 	u32			uid, pid, seq, sid;
654 	void			*data;
655 	struct audit_status	*status_get, status_set;
656 	int			err;
657 	struct audit_buffer	*ab;
658 	u16			msg_type = nlh->nlmsg_type;
659 	uid_t			loginuid; /* loginuid of sender */
660 	u32			sessionid;
661 	struct audit_sig_info   *sig_data;
662 	char			*ctx = NULL;
663 	u32			len;
664 
665 	err = audit_netlink_ok(skb, msg_type);
666 	if (err)
667 		return err;
668 
669 	/* As soon as there's any sign of userspace auditd,
670 	 * start kauditd to talk to it */
671 	if (!kauditd_task)
672 		kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
673 	if (IS_ERR(kauditd_task)) {
674 		err = PTR_ERR(kauditd_task);
675 		kauditd_task = NULL;
676 		return err;
677 	}
678 
679 	pid  = NETLINK_CREDS(skb)->pid;
680 	uid  = NETLINK_CREDS(skb)->uid;
681 	loginuid = NETLINK_CB(skb).loginuid;
682 	sessionid = NETLINK_CB(skb).sessionid;
683 	sid  = NETLINK_CB(skb).sid;
684 	seq  = nlh->nlmsg_seq;
685 	data = NLMSG_DATA(nlh);
686 
687 	switch (msg_type) {
688 	case AUDIT_GET:
689 		status_set.enabled	 = audit_enabled;
690 		status_set.failure	 = audit_failure;
691 		status_set.pid		 = audit_pid;
692 		status_set.rate_limit	 = audit_rate_limit;
693 		status_set.backlog_limit = audit_backlog_limit;
694 		status_set.lost		 = atomic_read(&audit_lost);
695 		status_set.backlog	 = skb_queue_len(&audit_skb_queue);
696 		audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
697 				 &status_set, sizeof(status_set));
698 		break;
699 	case AUDIT_SET:
700 		if (nlh->nlmsg_len < sizeof(struct audit_status))
701 			return -EINVAL;
702 		status_get   = (struct audit_status *)data;
703 		if (status_get->mask & AUDIT_STATUS_ENABLED) {
704 			err = audit_set_enabled(status_get->enabled,
705 						loginuid, sessionid, sid);
706 			if (err < 0)
707 				return err;
708 		}
709 		if (status_get->mask & AUDIT_STATUS_FAILURE) {
710 			err = audit_set_failure(status_get->failure,
711 						loginuid, sessionid, sid);
712 			if (err < 0)
713 				return err;
714 		}
715 		if (status_get->mask & AUDIT_STATUS_PID) {
716 			int new_pid = status_get->pid;
717 
718 			if (audit_enabled != AUDIT_OFF)
719 				audit_log_config_change("audit_pid", new_pid,
720 							audit_pid, loginuid,
721 							sessionid, sid, 1);
722 
723 			audit_pid = new_pid;
724 			audit_nlk_pid = NETLINK_CB(skb).pid;
725 		}
726 		if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
727 			err = audit_set_rate_limit(status_get->rate_limit,
728 						   loginuid, sessionid, sid);
729 			if (err < 0)
730 				return err;
731 		}
732 		if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
733 			err = audit_set_backlog_limit(status_get->backlog_limit,
734 						      loginuid, sessionid, sid);
735 		break;
736 	case AUDIT_USER:
737 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
738 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
739 		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
740 			return 0;
741 
742 		err = audit_filter_user(&NETLINK_CB(skb));
743 		if (err == 1) {
744 			err = 0;
745 			if (msg_type == AUDIT_USER_TTY) {
746 				err = audit_prepare_user_tty(pid, loginuid,
747 							     sessionid);
748 				if (err)
749 					break;
750 			}
751 			audit_log_common_recv_msg(&ab, msg_type, pid, uid,
752 						  loginuid, sessionid, sid);
753 
754 			if (msg_type != AUDIT_USER_TTY)
755 				audit_log_format(ab, " msg='%.1024s'",
756 						 (char *)data);
757 			else {
758 				int size;
759 
760 				audit_log_format(ab, " msg=");
761 				size = nlmsg_len(nlh);
762 				if (size > 0 &&
763 				    ((unsigned char *)data)[size - 1] == '\0')
764 					size--;
765 				audit_log_n_untrustedstring(ab, data, size);
766 			}
767 			audit_set_pid(ab, pid);
768 			audit_log_end(ab);
769 		}
770 		break;
771 	case AUDIT_ADD:
772 	case AUDIT_DEL:
773 		if (nlmsg_len(nlh) < sizeof(struct audit_rule))
774 			return -EINVAL;
775 		if (audit_enabled == AUDIT_LOCKED) {
776 			audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
777 						  uid, loginuid, sessionid, sid);
778 
779 			audit_log_format(ab, " audit_enabled=%d res=0",
780 					 audit_enabled);
781 			audit_log_end(ab);
782 			return -EPERM;
783 		}
784 		/* fallthrough */
785 	case AUDIT_LIST:
786 		err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
787 					   uid, seq, data, nlmsg_len(nlh),
788 					   loginuid, sessionid, sid);
789 		break;
790 	case AUDIT_ADD_RULE:
791 	case AUDIT_DEL_RULE:
792 		if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
793 			return -EINVAL;
794 		if (audit_enabled == AUDIT_LOCKED) {
795 			audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
796 						  uid, loginuid, sessionid, sid);
797 
798 			audit_log_format(ab, " audit_enabled=%d res=0",
799 					 audit_enabled);
800 			audit_log_end(ab);
801 			return -EPERM;
802 		}
803 		/* fallthrough */
804 	case AUDIT_LIST_RULES:
805 		err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
806 					   uid, seq, data, nlmsg_len(nlh),
807 					   loginuid, sessionid, sid);
808 		break;
809 	case AUDIT_TRIM:
810 		audit_trim_trees();
811 
812 		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
813 					  uid, loginuid, sessionid, sid);
814 
815 		audit_log_format(ab, " op=trim res=1");
816 		audit_log_end(ab);
817 		break;
818 	case AUDIT_MAKE_EQUIV: {
819 		void *bufp = data;
820 		u32 sizes[2];
821 		size_t msglen = nlmsg_len(nlh);
822 		char *old, *new;
823 
824 		err = -EINVAL;
825 		if (msglen < 2 * sizeof(u32))
826 			break;
827 		memcpy(sizes, bufp, 2 * sizeof(u32));
828 		bufp += 2 * sizeof(u32);
829 		msglen -= 2 * sizeof(u32);
830 		old = audit_unpack_string(&bufp, &msglen, sizes[0]);
831 		if (IS_ERR(old)) {
832 			err = PTR_ERR(old);
833 			break;
834 		}
835 		new = audit_unpack_string(&bufp, &msglen, sizes[1]);
836 		if (IS_ERR(new)) {
837 			err = PTR_ERR(new);
838 			kfree(old);
839 			break;
840 		}
841 		/* OK, here comes... */
842 		err = audit_tag_tree(old, new);
843 
844 		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
845 					  uid, loginuid, sessionid, sid);
846 
847 		audit_log_format(ab, " op=make_equiv old=");
848 		audit_log_untrustedstring(ab, old);
849 		audit_log_format(ab, " new=");
850 		audit_log_untrustedstring(ab, new);
851 		audit_log_format(ab, " res=%d", !err);
852 		audit_log_end(ab);
853 		kfree(old);
854 		kfree(new);
855 		break;
856 	}
857 	case AUDIT_SIGNAL_INFO:
858 		len = 0;
859 		if (audit_sig_sid) {
860 			err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
861 			if (err)
862 				return err;
863 		}
864 		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
865 		if (!sig_data) {
866 			if (audit_sig_sid)
867 				security_release_secctx(ctx, len);
868 			return -ENOMEM;
869 		}
870 		sig_data->uid = audit_sig_uid;
871 		sig_data->pid = audit_sig_pid;
872 		if (audit_sig_sid) {
873 			memcpy(sig_data->ctx, ctx, len);
874 			security_release_secctx(ctx, len);
875 		}
876 		audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
877 				0, 0, sig_data, sizeof(*sig_data) + len);
878 		kfree(sig_data);
879 		break;
880 	case AUDIT_TTY_GET: {
881 		struct audit_tty_status s;
882 		struct task_struct *tsk;
883 
884 		read_lock(&tasklist_lock);
885 		tsk = find_task_by_vpid(pid);
886 		if (!tsk)
887 			err = -ESRCH;
888 		else {
889 			spin_lock_irq(&tsk->sighand->siglock);
890 			s.enabled = tsk->signal->audit_tty != 0;
891 			spin_unlock_irq(&tsk->sighand->siglock);
892 		}
893 		read_unlock(&tasklist_lock);
894 		audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0,
895 				 &s, sizeof(s));
896 		break;
897 	}
898 	case AUDIT_TTY_SET: {
899 		struct audit_tty_status *s;
900 		struct task_struct *tsk;
901 
902 		if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
903 			return -EINVAL;
904 		s = data;
905 		if (s->enabled != 0 && s->enabled != 1)
906 			return -EINVAL;
907 		read_lock(&tasklist_lock);
908 		tsk = find_task_by_vpid(pid);
909 		if (!tsk)
910 			err = -ESRCH;
911 		else {
912 			spin_lock_irq(&tsk->sighand->siglock);
913 			tsk->signal->audit_tty = s->enabled != 0;
914 			spin_unlock_irq(&tsk->sighand->siglock);
915 		}
916 		read_unlock(&tasklist_lock);
917 		break;
918 	}
919 	default:
920 		err = -EINVAL;
921 		break;
922 	}
923 
924 	return err < 0 ? err : 0;
925 }
926 
927 /*
928  * Get message from skb.  Each message is processed by audit_receive_msg.
929  * Malformed skbs with wrong length are discarded silently.
930  */
931 static void audit_receive_skb(struct sk_buff *skb)
932 {
933 	struct nlmsghdr *nlh;
934 	/*
935 	 * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
936 	 * if the nlmsg_len was not aligned
937 	 */
938 	int len;
939 	int err;
940 
941 	nlh = nlmsg_hdr(skb);
942 	len = skb->len;
943 
944 	while (NLMSG_OK(nlh, len)) {
945 		err = audit_receive_msg(skb, nlh);
946 		/* if err or if this message says it wants a response */
947 		if (err || (nlh->nlmsg_flags & NLM_F_ACK))
948 			netlink_ack(skb, nlh, err);
949 
950 		nlh = NLMSG_NEXT(nlh, len);
951 	}
952 }
953 
954 /* Receive messages from netlink socket. */
955 static void audit_receive(struct sk_buff  *skb)
956 {
957 	mutex_lock(&audit_cmd_mutex);
958 	audit_receive_skb(skb);
959 	mutex_unlock(&audit_cmd_mutex);
960 }
961 
962 /* Initialize audit support at boot time. */
963 static int __init audit_init(void)
964 {
965 	int i;
966 
967 	if (audit_initialized == AUDIT_DISABLED)
968 		return 0;
969 
970 	printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
971 	       audit_default ? "enabled" : "disabled");
972 	audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
973 					   audit_receive, NULL, THIS_MODULE);
974 	if (!audit_sock)
975 		audit_panic("cannot initialize netlink socket");
976 	else
977 		audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
978 
979 	skb_queue_head_init(&audit_skb_queue);
980 	skb_queue_head_init(&audit_skb_hold_queue);
981 	audit_initialized = AUDIT_INITIALIZED;
982 	audit_enabled = audit_default;
983 	audit_ever_enabled |= !!audit_default;
984 
985 	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
986 
987 	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
988 		INIT_LIST_HEAD(&audit_inode_hash[i]);
989 
990 	return 0;
991 }
992 __initcall(audit_init);
993 
994 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
995 static int __init audit_enable(char *str)
996 {
997 	audit_default = !!simple_strtol(str, NULL, 0);
998 	if (!audit_default)
999 		audit_initialized = AUDIT_DISABLED;
1000 
1001 	printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
1002 
1003 	if (audit_initialized == AUDIT_INITIALIZED) {
1004 		audit_enabled = audit_default;
1005 		audit_ever_enabled |= !!audit_default;
1006 	} else if (audit_initialized == AUDIT_UNINITIALIZED) {
1007 		printk(" (after initialization)");
1008 	} else {
1009 		printk(" (until reboot)");
1010 	}
1011 	printk("\n");
1012 
1013 	return 1;
1014 }
1015 
1016 __setup("audit=", audit_enable);
1017 
1018 static void audit_buffer_free(struct audit_buffer *ab)
1019 {
1020 	unsigned long flags;
1021 
1022 	if (!ab)
1023 		return;
1024 
1025 	if (ab->skb)
1026 		kfree_skb(ab->skb);
1027 
1028 	spin_lock_irqsave(&audit_freelist_lock, flags);
1029 	if (audit_freelist_count > AUDIT_MAXFREE)
1030 		kfree(ab);
1031 	else {
1032 		audit_freelist_count++;
1033 		list_add(&ab->list, &audit_freelist);
1034 	}
1035 	spin_unlock_irqrestore(&audit_freelist_lock, flags);
1036 }
1037 
1038 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1039 						gfp_t gfp_mask, int type)
1040 {
1041 	unsigned long flags;
1042 	struct audit_buffer *ab = NULL;
1043 	struct nlmsghdr *nlh;
1044 
1045 	spin_lock_irqsave(&audit_freelist_lock, flags);
1046 	if (!list_empty(&audit_freelist)) {
1047 		ab = list_entry(audit_freelist.next,
1048 				struct audit_buffer, list);
1049 		list_del(&ab->list);
1050 		--audit_freelist_count;
1051 	}
1052 	spin_unlock_irqrestore(&audit_freelist_lock, flags);
1053 
1054 	if (!ab) {
1055 		ab = kmalloc(sizeof(*ab), gfp_mask);
1056 		if (!ab)
1057 			goto err;
1058 	}
1059 
1060 	ab->ctx = ctx;
1061 	ab->gfp_mask = gfp_mask;
1062 
1063 	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1064 	if (!ab->skb)
1065 		goto nlmsg_failure;
1066 
1067 	nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0);
1068 
1069 	return ab;
1070 
1071 nlmsg_failure:                  /* Used by NLMSG_NEW */
1072 	kfree_skb(ab->skb);
1073 	ab->skb = NULL;
1074 err:
1075 	audit_buffer_free(ab);
1076 	return NULL;
1077 }
1078 
1079 /**
1080  * audit_serial - compute a serial number for the audit record
1081  *
1082  * Compute a serial number for the audit record.  Audit records are
1083  * written to user-space as soon as they are generated, so a complete
1084  * audit record may be written in several pieces.  The timestamp of the
1085  * record and this serial number are used by the user-space tools to
1086  * determine which pieces belong to the same audit record.  The
1087  * (timestamp,serial) tuple is unique for each syscall and is live from
1088  * syscall entry to syscall exit.
1089  *
1090  * NOTE: Another possibility is to store the formatted records off the
1091  * audit context (for those records that have a context), and emit them
1092  * all at syscall exit.  However, this could delay the reporting of
1093  * significant errors until syscall exit (or never, if the system
1094  * halts).
1095  */
1096 unsigned int audit_serial(void)
1097 {
1098 	static DEFINE_SPINLOCK(serial_lock);
1099 	static unsigned int serial = 0;
1100 
1101 	unsigned long flags;
1102 	unsigned int ret;
1103 
1104 	spin_lock_irqsave(&serial_lock, flags);
1105 	do {
1106 		ret = ++serial;
1107 	} while (unlikely(!ret));
1108 	spin_unlock_irqrestore(&serial_lock, flags);
1109 
1110 	return ret;
1111 }
1112 
1113 static inline void audit_get_stamp(struct audit_context *ctx,
1114 				   struct timespec *t, unsigned int *serial)
1115 {
1116 	if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1117 		*t = CURRENT_TIME;
1118 		*serial = audit_serial();
1119 	}
1120 }
1121 
1122 /* Obtain an audit buffer.  This routine does locking to obtain the
1123  * audit buffer, but then no locking is required for calls to
1124  * audit_log_*format.  If the tsk is a task that is currently in a
1125  * syscall, then the syscall is marked as auditable and an audit record
1126  * will be written at syscall exit.  If there is no associated task, tsk
1127  * should be NULL. */
1128 
1129 /**
1130  * audit_log_start - obtain an audit buffer
1131  * @ctx: audit_context (may be NULL)
1132  * @gfp_mask: type of allocation
1133  * @type: audit message type
1134  *
1135  * Returns audit_buffer pointer on success or NULL on error.
1136  *
1137  * Obtain an audit buffer.  This routine does locking to obtain the
1138  * audit buffer, but then no locking is required for calls to
1139  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1140  * syscall, then the syscall is marked as auditable and an audit record
1141  * will be written at syscall exit.  If there is no associated task, then
1142  * task context (ctx) should be NULL.
1143  */
1144 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1145 				     int type)
1146 {
1147 	struct audit_buffer	*ab	= NULL;
1148 	struct timespec		t;
1149 	unsigned int		uninitialized_var(serial);
1150 	int reserve;
1151 	unsigned long timeout_start = jiffies;
1152 
1153 	if (audit_initialized != AUDIT_INITIALIZED)
1154 		return NULL;
1155 
1156 	if (unlikely(audit_filter_type(type)))
1157 		return NULL;
1158 
1159 	if (gfp_mask & __GFP_WAIT)
1160 		reserve = 0;
1161 	else
1162 		reserve = 5; /* Allow atomic callers to go up to five
1163 				entries over the normal backlog limit */
1164 
1165 	while (audit_backlog_limit
1166 	       && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1167 		if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1168 		    && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1169 
1170 			/* Wait for auditd to drain the queue a little */
1171 			DECLARE_WAITQUEUE(wait, current);
1172 			set_current_state(TASK_INTERRUPTIBLE);
1173 			add_wait_queue(&audit_backlog_wait, &wait);
1174 
1175 			if (audit_backlog_limit &&
1176 			    skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1177 				schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1178 
1179 			__set_current_state(TASK_RUNNING);
1180 			remove_wait_queue(&audit_backlog_wait, &wait);
1181 			continue;
1182 		}
1183 		if (audit_rate_check() && printk_ratelimit())
1184 			printk(KERN_WARNING
1185 			       "audit: audit_backlog=%d > "
1186 			       "audit_backlog_limit=%d\n",
1187 			       skb_queue_len(&audit_skb_queue),
1188 			       audit_backlog_limit);
1189 		audit_log_lost("backlog limit exceeded");
1190 		audit_backlog_wait_time = audit_backlog_wait_overflow;
1191 		wake_up(&audit_backlog_wait);
1192 		return NULL;
1193 	}
1194 
1195 	ab = audit_buffer_alloc(ctx, gfp_mask, type);
1196 	if (!ab) {
1197 		audit_log_lost("out of memory in audit_log_start");
1198 		return NULL;
1199 	}
1200 
1201 	audit_get_stamp(ab->ctx, &t, &serial);
1202 
1203 	audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1204 			 t.tv_sec, t.tv_nsec/1000000, serial);
1205 	return ab;
1206 }
1207 
1208 /**
1209  * audit_expand - expand skb in the audit buffer
1210  * @ab: audit_buffer
1211  * @extra: space to add at tail of the skb
1212  *
1213  * Returns 0 (no space) on failed expansion, or available space if
1214  * successful.
1215  */
1216 static inline int audit_expand(struct audit_buffer *ab, int extra)
1217 {
1218 	struct sk_buff *skb = ab->skb;
1219 	int oldtail = skb_tailroom(skb);
1220 	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1221 	int newtail = skb_tailroom(skb);
1222 
1223 	if (ret < 0) {
1224 		audit_log_lost("out of memory in audit_expand");
1225 		return 0;
1226 	}
1227 
1228 	skb->truesize += newtail - oldtail;
1229 	return newtail;
1230 }
1231 
1232 /*
1233  * Format an audit message into the audit buffer.  If there isn't enough
1234  * room in the audit buffer, more room will be allocated and vsnprint
1235  * will be called a second time.  Currently, we assume that a printk
1236  * can't format message larger than 1024 bytes, so we don't either.
1237  */
1238 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1239 			      va_list args)
1240 {
1241 	int len, avail;
1242 	struct sk_buff *skb;
1243 	va_list args2;
1244 
1245 	if (!ab)
1246 		return;
1247 
1248 	BUG_ON(!ab->skb);
1249 	skb = ab->skb;
1250 	avail = skb_tailroom(skb);
1251 	if (avail == 0) {
1252 		avail = audit_expand(ab, AUDIT_BUFSIZ);
1253 		if (!avail)
1254 			goto out;
1255 	}
1256 	va_copy(args2, args);
1257 	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1258 	if (len >= avail) {
1259 		/* The printk buffer is 1024 bytes long, so if we get
1260 		 * here and AUDIT_BUFSIZ is at least 1024, then we can
1261 		 * log everything that printk could have logged. */
1262 		avail = audit_expand(ab,
1263 			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1264 		if (!avail)
1265 			goto out;
1266 		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1267 	}
1268 	va_end(args2);
1269 	if (len > 0)
1270 		skb_put(skb, len);
1271 out:
1272 	return;
1273 }
1274 
1275 /**
1276  * audit_log_format - format a message into the audit buffer.
1277  * @ab: audit_buffer
1278  * @fmt: format string
1279  * @...: optional parameters matching @fmt string
1280  *
1281  * All the work is done in audit_log_vformat.
1282  */
1283 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1284 {
1285 	va_list args;
1286 
1287 	if (!ab)
1288 		return;
1289 	va_start(args, fmt);
1290 	audit_log_vformat(ab, fmt, args);
1291 	va_end(args);
1292 }
1293 
1294 /**
1295  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1296  * @ab: the audit_buffer
1297  * @buf: buffer to convert to hex
1298  * @len: length of @buf to be converted
1299  *
1300  * No return value; failure to expand is silently ignored.
1301  *
1302  * This function will take the passed buf and convert it into a string of
1303  * ascii hex digits. The new string is placed onto the skb.
1304  */
1305 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1306 		size_t len)
1307 {
1308 	int i, avail, new_len;
1309 	unsigned char *ptr;
1310 	struct sk_buff *skb;
1311 	static const unsigned char *hex = "0123456789ABCDEF";
1312 
1313 	if (!ab)
1314 		return;
1315 
1316 	BUG_ON(!ab->skb);
1317 	skb = ab->skb;
1318 	avail = skb_tailroom(skb);
1319 	new_len = len<<1;
1320 	if (new_len >= avail) {
1321 		/* Round the buffer request up to the next multiple */
1322 		new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1323 		avail = audit_expand(ab, new_len);
1324 		if (!avail)
1325 			return;
1326 	}
1327 
1328 	ptr = skb_tail_pointer(skb);
1329 	for (i=0; i<len; i++) {
1330 		*ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1331 		*ptr++ = hex[buf[i] & 0x0F];	  /* Lower nibble */
1332 	}
1333 	*ptr = 0;
1334 	skb_put(skb, len << 1); /* new string is twice the old string */
1335 }
1336 
1337 /*
1338  * Format a string of no more than slen characters into the audit buffer,
1339  * enclosed in quote marks.
1340  */
1341 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1342 			size_t slen)
1343 {
1344 	int avail, new_len;
1345 	unsigned char *ptr;
1346 	struct sk_buff *skb;
1347 
1348 	if (!ab)
1349 		return;
1350 
1351 	BUG_ON(!ab->skb);
1352 	skb = ab->skb;
1353 	avail = skb_tailroom(skb);
1354 	new_len = slen + 3;	/* enclosing quotes + null terminator */
1355 	if (new_len > avail) {
1356 		avail = audit_expand(ab, new_len);
1357 		if (!avail)
1358 			return;
1359 	}
1360 	ptr = skb_tail_pointer(skb);
1361 	*ptr++ = '"';
1362 	memcpy(ptr, string, slen);
1363 	ptr += slen;
1364 	*ptr++ = '"';
1365 	*ptr = 0;
1366 	skb_put(skb, slen + 2);	/* don't include null terminator */
1367 }
1368 
1369 /**
1370  * audit_string_contains_control - does a string need to be logged in hex
1371  * @string: string to be checked
1372  * @len: max length of the string to check
1373  */
1374 int audit_string_contains_control(const char *string, size_t len)
1375 {
1376 	const unsigned char *p;
1377 	for (p = string; p < (const unsigned char *)string + len; p++) {
1378 		if (*p == '"' || *p < 0x21 || *p > 0x7e)
1379 			return 1;
1380 	}
1381 	return 0;
1382 }
1383 
1384 /**
1385  * audit_log_n_untrustedstring - log a string that may contain random characters
1386  * @ab: audit_buffer
1387  * @len: length of string (not including trailing null)
1388  * @string: string to be logged
1389  *
1390  * This code will escape a string that is passed to it if the string
1391  * contains a control character, unprintable character, double quote mark,
1392  * or a space. Unescaped strings will start and end with a double quote mark.
1393  * Strings that are escaped are printed in hex (2 digits per char).
1394  *
1395  * The caller specifies the number of characters in the string to log, which may
1396  * or may not be the entire string.
1397  */
1398 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1399 				 size_t len)
1400 {
1401 	if (audit_string_contains_control(string, len))
1402 		audit_log_n_hex(ab, string, len);
1403 	else
1404 		audit_log_n_string(ab, string, len);
1405 }
1406 
1407 /**
1408  * audit_log_untrustedstring - log a string that may contain random characters
1409  * @ab: audit_buffer
1410  * @string: string to be logged
1411  *
1412  * Same as audit_log_n_untrustedstring(), except that strlen is used to
1413  * determine string length.
1414  */
1415 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1416 {
1417 	audit_log_n_untrustedstring(ab, string, strlen(string));
1418 }
1419 
1420 /* This is a helper-function to print the escaped d_path */
1421 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1422 		      struct path *path)
1423 {
1424 	char *p, *pathname;
1425 
1426 	if (prefix)
1427 		audit_log_format(ab, " %s", prefix);
1428 
1429 	/* We will allow 11 spaces for ' (deleted)' to be appended */
1430 	pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1431 	if (!pathname) {
1432 		audit_log_string(ab, "<no_memory>");
1433 		return;
1434 	}
1435 	p = d_path(path, pathname, PATH_MAX+11);
1436 	if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1437 		/* FIXME: can we save some information here? */
1438 		audit_log_string(ab, "<too_long>");
1439 	} else
1440 		audit_log_untrustedstring(ab, p);
1441 	kfree(pathname);
1442 }
1443 
1444 void audit_log_key(struct audit_buffer *ab, char *key)
1445 {
1446 	audit_log_format(ab, " key=");
1447 	if (key)
1448 		audit_log_untrustedstring(ab, key);
1449 	else
1450 		audit_log_format(ab, "(null)");
1451 }
1452 
1453 /**
1454  * audit_log_end - end one audit record
1455  * @ab: the audit_buffer
1456  *
1457  * The netlink_* functions cannot be called inside an irq context, so
1458  * the audit buffer is placed on a queue and a tasklet is scheduled to
1459  * remove them from the queue outside the irq context.  May be called in
1460  * any context.
1461  */
1462 void audit_log_end(struct audit_buffer *ab)
1463 {
1464 	if (!ab)
1465 		return;
1466 	if (!audit_rate_check()) {
1467 		audit_log_lost("rate limit exceeded");
1468 	} else {
1469 		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1470 		nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1471 
1472 		if (audit_pid) {
1473 			skb_queue_tail(&audit_skb_queue, ab->skb);
1474 			wake_up_interruptible(&kauditd_wait);
1475 		} else {
1476 			audit_printk_skb(ab->skb);
1477 		}
1478 		ab->skb = NULL;
1479 	}
1480 	audit_buffer_free(ab);
1481 }
1482 
1483 /**
1484  * audit_log - Log an audit record
1485  * @ctx: audit context
1486  * @gfp_mask: type of allocation
1487  * @type: audit message type
1488  * @fmt: format string to use
1489  * @...: variable parameters matching the format string
1490  *
1491  * This is a convenience function that calls audit_log_start,
1492  * audit_log_vformat, and audit_log_end.  It may be called
1493  * in any context.
1494  */
1495 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1496 	       const char *fmt, ...)
1497 {
1498 	struct audit_buffer *ab;
1499 	va_list args;
1500 
1501 	ab = audit_log_start(ctx, gfp_mask, type);
1502 	if (ab) {
1503 		va_start(args, fmt);
1504 		audit_log_vformat(ab, fmt, args);
1505 		va_end(args);
1506 		audit_log_end(ab);
1507 	}
1508 }
1509 
1510 EXPORT_SYMBOL(audit_log_start);
1511 EXPORT_SYMBOL(audit_log_end);
1512 EXPORT_SYMBOL(audit_log_format);
1513 EXPORT_SYMBOL(audit_log);
1514