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TOMOYO Linux Cross Reference
Linux/kernel/audit.c

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  1 /* audit.c -- Auditing support
  2  * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
  3  * System-call specific features have moved to auditsc.c
  4  *
  5  * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
  6  * All Rights Reserved.
  7  *
  8  * This program is free software; you can redistribute it and/or modify
  9  * it under the terms of the GNU General Public License as published by
 10  * the Free Software Foundation; either version 2 of the License, or
 11  * (at your option) any later version.
 12  *
 13  * This program is distributed in the hope that it will be useful,
 14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16  * GNU General Public License for more details.
 17  *
 18  * You should have received a copy of the GNU General Public License
 19  * along with this program; if not, write to the Free Software
 20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 21  *
 22  * Written by Rickard E. (Rik) Faith <faith@redhat.com>
 23  *
 24  * Goals: 1) Integrate fully with Security Modules.
 25  *        2) Minimal run-time overhead:
 26  *           a) Minimal when syscall auditing is disabled (audit_enable=0).
 27  *           b) Small when syscall auditing is enabled and no audit record
 28  *              is generated (defer as much work as possible to record
 29  *              generation time):
 30  *              i) context is allocated,
 31  *              ii) names from getname are stored without a copy, and
 32  *              iii) inode information stored from path_lookup.
 33  *        3) Ability to disable syscall auditing at boot time (audit=0).
 34  *        4) Usable by other parts of the kernel (if audit_log* is called,
 35  *           then a syscall record will be generated automatically for the
 36  *           current syscall).
 37  *        5) Netlink interface to user-space.
 38  *        6) Support low-overhead kernel-based filtering to minimize the
 39  *           information that must be passed to user-space.
 40  *
 41  * Example user-space utilities: http://people.redhat.com/sgrubb/audit/
 42  */
 43 
 44 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 45 
 46 #include <linux/file.h>
 47 #include <linux/init.h>
 48 #include <linux/types.h>
 49 #include <linux/atomic.h>
 50 #include <linux/mm.h>
 51 #include <linux/export.h>
 52 #include <linux/slab.h>
 53 #include <linux/err.h>
 54 #include <linux/kthread.h>
 55 #include <linux/kernel.h>
 56 #include <linux/syscalls.h>
 57 
 58 #include <linux/audit.h>
 59 
 60 #include <net/sock.h>
 61 #include <net/netlink.h>
 62 #include <linux/skbuff.h>
 63 #ifdef CONFIG_SECURITY
 64 #include <linux/security.h>
 65 #endif
 66 #include <linux/freezer.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_master = AUDIT_BACKLOG_WAIT_TIME;
111 static u32      audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
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_master, timeout);
342 }
343 
344 static int audit_set_enabled(u32 state)
345 {
346         int rc;
347         if (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         int attempts = 0;
409 #define AUDITD_RETRIES 5
410 
411 restart:
412         /* take a reference in case we can't send it and we want to hold it */
413         skb_get(skb);
414         err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
415         if (err < 0) {
416                 pr_err("netlink_unicast sending to audit_pid=%d returned error: %d\n",
417                        audit_pid, err);
418                 if (audit_pid) {
419                         if (err == -ECONNREFUSED || err == -EPERM
420                             || ++attempts >= AUDITD_RETRIES) {
421                                 char s[32];
422 
423                                 snprintf(s, sizeof(s), "audit_pid=%d reset", audit_pid);
424                                 audit_log_lost(s);
425                                 audit_pid = 0;
426                                 audit_sock = NULL;
427                         } else {
428                                 pr_warn("re-scheduling(#%d) write to audit_pid=%d\n",
429                                         attempts, audit_pid);
430                                 set_current_state(TASK_INTERRUPTIBLE);
431                                 schedule();
432                                 goto restart;
433                         }
434                 }
435                 /* we might get lucky and get this in the next auditd */
436                 audit_hold_skb(skb);
437         } else
438                 /* drop the extra reference if sent ok */
439                 consume_skb(skb);
440 }
441 
442 /*
443  * kauditd_send_multicast_skb - send the skb to multicast userspace listeners
444  *
445  * This function doesn't consume an skb as might be expected since it has to
446  * copy it anyways.
447  */
448 static void kauditd_send_multicast_skb(struct sk_buff *skb, gfp_t gfp_mask)
449 {
450         struct sk_buff          *copy;
451         struct audit_net        *aunet = net_generic(&init_net, audit_net_id);
452         struct sock             *sock = aunet->nlsk;
453 
454         if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
455                 return;
456 
457         /*
458          * The seemingly wasteful skb_copy() rather than bumping the refcount
459          * using skb_get() is necessary because non-standard mods are made to
460          * the skb by the original kaudit unicast socket send routine.  The
461          * existing auditd daemon assumes this breakage.  Fixing this would
462          * require co-ordinating a change in the established protocol between
463          * the kaudit kernel subsystem and the auditd userspace code.  There is
464          * no reason for new multicast clients to continue with this
465          * non-compliance.
466          */
467         copy = skb_copy(skb, gfp_mask);
468         if (!copy)
469                 return;
470 
471         nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, gfp_mask);
472 }
473 
474 /*
475  * flush_hold_queue - empty the hold queue if auditd appears
476  *
477  * If auditd just started, drain the queue of messages already
478  * sent to syslog/printk.  Remember loss here is ok.  We already
479  * called audit_log_lost() if it didn't go out normally.  so the
480  * race between the skb_dequeue and the next check for audit_pid
481  * doesn't matter.
482  *
483  * If you ever find kauditd to be too slow we can get a perf win
484  * by doing our own locking and keeping better track if there
485  * are messages in this queue.  I don't see the need now, but
486  * in 5 years when I want to play with this again I'll see this
487  * note and still have no friggin idea what i'm thinking today.
488  */
489 static void flush_hold_queue(void)
490 {
491         struct sk_buff *skb;
492 
493         if (!audit_default || !audit_pid)
494                 return;
495 
496         skb = skb_dequeue(&audit_skb_hold_queue);
497         if (likely(!skb))
498                 return;
499 
500         while (skb && audit_pid) {
501                 kauditd_send_skb(skb);
502                 skb = skb_dequeue(&audit_skb_hold_queue);
503         }
504 
505         /*
506          * if auditd just disappeared but we
507          * dequeued an skb we need to drop ref
508          */
509         consume_skb(skb);
510 }
511 
512 static int kauditd_thread(void *dummy)
513 {
514         set_freezable();
515         while (!kthread_should_stop()) {
516                 struct sk_buff *skb;
517 
518                 flush_hold_queue();
519 
520                 skb = skb_dequeue(&audit_skb_queue);
521 
522                 if (skb) {
523                         if (!audit_backlog_limit ||
524                             (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit))
525                                 wake_up(&audit_backlog_wait);
526                         if (audit_pid)
527                                 kauditd_send_skb(skb);
528                         else
529                                 audit_printk_skb(skb);
530                         continue;
531                 }
532 
533                 wait_event_freezable(kauditd_wait, skb_queue_len(&audit_skb_queue));
534         }
535         return 0;
536 }
537 
538 int audit_send_list(void *_dest)
539 {
540         struct audit_netlink_list *dest = _dest;
541         struct sk_buff *skb;
542         struct net *net = dest->net;
543         struct audit_net *aunet = net_generic(net, audit_net_id);
544 
545         /* wait for parent to finish and send an ACK */
546         mutex_lock(&audit_cmd_mutex);
547         mutex_unlock(&audit_cmd_mutex);
548 
549         while ((skb = __skb_dequeue(&dest->q)) != NULL)
550                 netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
551 
552         put_net(net);
553         kfree(dest);
554 
555         return 0;
556 }
557 
558 struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
559                                  int multi, const void *payload, int size)
560 {
561         struct sk_buff  *skb;
562         struct nlmsghdr *nlh;
563         void            *data;
564         int             flags = multi ? NLM_F_MULTI : 0;
565         int             t     = done  ? NLMSG_DONE  : type;
566 
567         skb = nlmsg_new(size, GFP_KERNEL);
568         if (!skb)
569                 return NULL;
570 
571         nlh     = nlmsg_put(skb, portid, seq, t, size, flags);
572         if (!nlh)
573                 goto out_kfree_skb;
574         data = nlmsg_data(nlh);
575         memcpy(data, payload, size);
576         return skb;
577 
578 out_kfree_skb:
579         kfree_skb(skb);
580         return NULL;
581 }
582 
583 static int audit_send_reply_thread(void *arg)
584 {
585         struct audit_reply *reply = (struct audit_reply *)arg;
586         struct net *net = reply->net;
587         struct audit_net *aunet = net_generic(net, audit_net_id);
588 
589         mutex_lock(&audit_cmd_mutex);
590         mutex_unlock(&audit_cmd_mutex);
591 
592         /* Ignore failure. It'll only happen if the sender goes away,
593            because our timeout is set to infinite. */
594         netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
595         put_net(net);
596         kfree(reply);
597         return 0;
598 }
599 /**
600  * audit_send_reply - send an audit reply message via netlink
601  * @request_skb: skb of request we are replying to (used to target the reply)
602  * @seq: sequence number
603  * @type: audit message type
604  * @done: done (last) flag
605  * @multi: multi-part message flag
606  * @payload: payload data
607  * @size: payload size
608  *
609  * Allocates an skb, builds the netlink message, and sends it to the port id.
610  * No failure notifications.
611  */
612 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
613                              int multi, const void *payload, int size)
614 {
615         u32 portid = NETLINK_CB(request_skb).portid;
616         struct net *net = sock_net(NETLINK_CB(request_skb).sk);
617         struct sk_buff *skb;
618         struct task_struct *tsk;
619         struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
620                                             GFP_KERNEL);
621 
622         if (!reply)
623                 return;
624 
625         skb = audit_make_reply(portid, seq, type, done, multi, payload, size);
626         if (!skb)
627                 goto out;
628 
629         reply->net = get_net(net);
630         reply->portid = portid;
631         reply->skb = skb;
632 
633         tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
634         if (!IS_ERR(tsk))
635                 return;
636         kfree_skb(skb);
637 out:
638         kfree(reply);
639 }
640 
641 /*
642  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
643  * control messages.
644  */
645 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
646 {
647         int err = 0;
648 
649         /* Only support initial user namespace for now. */
650         /*
651          * We return ECONNREFUSED because it tricks userspace into thinking
652          * that audit was not configured into the kernel.  Lots of users
653          * configure their PAM stack (because that's what the distro does)
654          * to reject login if unable to send messages to audit.  If we return
655          * ECONNREFUSED the PAM stack thinks the kernel does not have audit
656          * configured in and will let login proceed.  If we return EPERM
657          * userspace will reject all logins.  This should be removed when we
658          * support non init namespaces!!
659          */
660         if (current_user_ns() != &init_user_ns)
661                 return -ECONNREFUSED;
662 
663         switch (msg_type) {
664         case AUDIT_LIST:
665         case AUDIT_ADD:
666         case AUDIT_DEL:
667                 return -EOPNOTSUPP;
668         case AUDIT_GET:
669         case AUDIT_SET:
670         case AUDIT_GET_FEATURE:
671         case AUDIT_SET_FEATURE:
672         case AUDIT_LIST_RULES:
673         case AUDIT_ADD_RULE:
674         case AUDIT_DEL_RULE:
675         case AUDIT_SIGNAL_INFO:
676         case AUDIT_TTY_GET:
677         case AUDIT_TTY_SET:
678         case AUDIT_TRIM:
679         case AUDIT_MAKE_EQUIV:
680                 /* Only support auditd and auditctl in initial pid namespace
681                  * for now. */
682                 if (task_active_pid_ns(current) != &init_pid_ns)
683                         return -EPERM;
684 
685                 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
686                         err = -EPERM;
687                 break;
688         case AUDIT_USER:
689         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
690         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
691                 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
692                         err = -EPERM;
693                 break;
694         default:  /* bad msg */
695                 err = -EINVAL;
696         }
697 
698         return err;
699 }
700 
701 static void audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
702 {
703         uid_t uid = from_kuid(&init_user_ns, current_uid());
704         pid_t pid = task_tgid_nr(current);
705 
706         if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
707                 *ab = NULL;
708                 return;
709         }
710 
711         *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
712         if (unlikely(!*ab))
713                 return;
714         audit_log_format(*ab, "pid=%d uid=%u", pid, uid);
715         audit_log_session_info(*ab);
716         audit_log_task_context(*ab);
717 }
718 
719 int is_audit_feature_set(int i)
720 {
721         return af.features & AUDIT_FEATURE_TO_MASK(i);
722 }
723 
724 
725 static int audit_get_feature(struct sk_buff *skb)
726 {
727         u32 seq;
728 
729         seq = nlmsg_hdr(skb)->nlmsg_seq;
730 
731         audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
732 
733         return 0;
734 }
735 
736 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
737                                      u32 old_lock, u32 new_lock, int res)
738 {
739         struct audit_buffer *ab;
740 
741         if (audit_enabled == AUDIT_OFF)
742                 return;
743 
744         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
745         audit_log_task_info(ab, current);
746         audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
747                          audit_feature_names[which], !!old_feature, !!new_feature,
748                          !!old_lock, !!new_lock, res);
749         audit_log_end(ab);
750 }
751 
752 static int audit_set_feature(struct sk_buff *skb)
753 {
754         struct audit_features *uaf;
755         int i;
756 
757         BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
758         uaf = nlmsg_data(nlmsg_hdr(skb));
759 
760         /* if there is ever a version 2 we should handle that here */
761 
762         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
763                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
764                 u32 old_feature, new_feature, old_lock, new_lock;
765 
766                 /* if we are not changing this feature, move along */
767                 if (!(feature & uaf->mask))
768                         continue;
769 
770                 old_feature = af.features & feature;
771                 new_feature = uaf->features & feature;
772                 new_lock = (uaf->lock | af.lock) & feature;
773                 old_lock = af.lock & feature;
774 
775                 /* are we changing a locked feature? */
776                 if (old_lock && (new_feature != old_feature)) {
777                         audit_log_feature_change(i, old_feature, new_feature,
778                                                  old_lock, new_lock, 0);
779                         return -EPERM;
780                 }
781         }
782         /* nothing invalid, do the changes */
783         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
784                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
785                 u32 old_feature, new_feature, old_lock, new_lock;
786 
787                 /* if we are not changing this feature, move along */
788                 if (!(feature & uaf->mask))
789                         continue;
790 
791                 old_feature = af.features & feature;
792                 new_feature = uaf->features & feature;
793                 old_lock = af.lock & feature;
794                 new_lock = (uaf->lock | af.lock) & feature;
795 
796                 if (new_feature != old_feature)
797                         audit_log_feature_change(i, old_feature, new_feature,
798                                                  old_lock, new_lock, 1);
799 
800                 if (new_feature)
801                         af.features |= feature;
802                 else
803                         af.features &= ~feature;
804                 af.lock |= new_lock;
805         }
806 
807         return 0;
808 }
809 
810 static int audit_replace(pid_t pid)
811 {
812         struct sk_buff *skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0,
813                                                &pid, sizeof(pid));
814 
815         if (!skb)
816                 return -ENOMEM;
817         return netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
818 }
819 
820 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
821 {
822         u32                     seq;
823         void                    *data;
824         int                     err;
825         struct audit_buffer     *ab;
826         u16                     msg_type = nlh->nlmsg_type;
827         struct audit_sig_info   *sig_data;
828         char                    *ctx = NULL;
829         u32                     len;
830 
831         err = audit_netlink_ok(skb, msg_type);
832         if (err)
833                 return err;
834 
835         /* As soon as there's any sign of userspace auditd,
836          * start kauditd to talk to it */
837         if (!kauditd_task) {
838                 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
839                 if (IS_ERR(kauditd_task)) {
840                         err = PTR_ERR(kauditd_task);
841                         kauditd_task = NULL;
842                         return err;
843                 }
844         }
845         seq  = nlh->nlmsg_seq;
846         data = nlmsg_data(nlh);
847 
848         switch (msg_type) {
849         case AUDIT_GET: {
850                 struct audit_status     s;
851                 memset(&s, 0, sizeof(s));
852                 s.enabled               = audit_enabled;
853                 s.failure               = audit_failure;
854                 s.pid                   = audit_pid;
855                 s.rate_limit            = audit_rate_limit;
856                 s.backlog_limit         = audit_backlog_limit;
857                 s.lost                  = atomic_read(&audit_lost);
858                 s.backlog               = skb_queue_len(&audit_skb_queue);
859                 s.feature_bitmap        = AUDIT_FEATURE_BITMAP_ALL;
860                 s.backlog_wait_time     = audit_backlog_wait_time_master;
861                 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
862                 break;
863         }
864         case AUDIT_SET: {
865                 struct audit_status     s;
866                 memset(&s, 0, sizeof(s));
867                 /* guard against past and future API changes */
868                 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
869                 if (s.mask & AUDIT_STATUS_ENABLED) {
870                         err = audit_set_enabled(s.enabled);
871                         if (err < 0)
872                                 return err;
873                 }
874                 if (s.mask & AUDIT_STATUS_FAILURE) {
875                         err = audit_set_failure(s.failure);
876                         if (err < 0)
877                                 return err;
878                 }
879                 if (s.mask & AUDIT_STATUS_PID) {
880                         int new_pid = s.pid;
881                         pid_t requesting_pid = task_tgid_vnr(current);
882 
883                         if ((!new_pid) && (requesting_pid != audit_pid)) {
884                                 audit_log_config_change("audit_pid", new_pid, audit_pid, 0);
885                                 return -EACCES;
886                         }
887                         if (audit_pid && new_pid &&
888                             audit_replace(requesting_pid) != -ECONNREFUSED) {
889                                 audit_log_config_change("audit_pid", new_pid, audit_pid, 0);
890                                 return -EEXIST;
891                         }
892                         if (audit_enabled != AUDIT_OFF)
893                                 audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
894                         audit_pid = new_pid;
895                         audit_nlk_portid = NETLINK_CB(skb).portid;
896                         audit_sock = skb->sk;
897                 }
898                 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
899                         err = audit_set_rate_limit(s.rate_limit);
900                         if (err < 0)
901                                 return err;
902                 }
903                 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
904                         err = audit_set_backlog_limit(s.backlog_limit);
905                         if (err < 0)
906                                 return err;
907                 }
908                 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
909                         if (sizeof(s) > (size_t)nlh->nlmsg_len)
910                                 return -EINVAL;
911                         if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
912                                 return -EINVAL;
913                         err = audit_set_backlog_wait_time(s.backlog_wait_time);
914                         if (err < 0)
915                                 return err;
916                 }
917                 break;
918         }
919         case AUDIT_GET_FEATURE:
920                 err = audit_get_feature(skb);
921                 if (err)
922                         return err;
923                 break;
924         case AUDIT_SET_FEATURE:
925                 err = audit_set_feature(skb);
926                 if (err)
927                         return err;
928                 break;
929         case AUDIT_USER:
930         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
931         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
932                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
933                         return 0;
934 
935                 err = audit_filter(msg_type, AUDIT_FILTER_USER);
936                 if (err == 1) { /* match or error */
937                         err = 0;
938                         if (msg_type == AUDIT_USER_TTY) {
939                                 err = tty_audit_push();
940                                 if (err)
941                                         break;
942                         }
943                         mutex_unlock(&audit_cmd_mutex);
944                         audit_log_common_recv_msg(&ab, msg_type);
945                         if (msg_type != AUDIT_USER_TTY)
946                                 audit_log_format(ab, " msg='%.*s'",
947                                                  AUDIT_MESSAGE_TEXT_MAX,
948                                                  (char *)data);
949                         else {
950                                 int size;
951 
952                                 audit_log_format(ab, " data=");
953                                 size = nlmsg_len(nlh);
954                                 if (size > 0 &&
955                                     ((unsigned char *)data)[size - 1] == '\0')
956                                         size--;
957                                 audit_log_n_untrustedstring(ab, data, size);
958                         }
959                         audit_set_portid(ab, NETLINK_CB(skb).portid);
960                         audit_log_end(ab);
961                         mutex_lock(&audit_cmd_mutex);
962                 }
963                 break;
964         case AUDIT_ADD_RULE:
965         case AUDIT_DEL_RULE:
966                 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
967                         return -EINVAL;
968                 if (audit_enabled == AUDIT_LOCKED) {
969                         audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
970                         audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
971                         audit_log_end(ab);
972                         return -EPERM;
973                 }
974                 err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
975                                            seq, data, nlmsg_len(nlh));
976                 break;
977         case AUDIT_LIST_RULES:
978                 err = audit_list_rules_send(skb, seq);
979                 break;
980         case AUDIT_TRIM:
981                 audit_trim_trees();
982                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
983                 audit_log_format(ab, " op=trim res=1");
984                 audit_log_end(ab);
985                 break;
986         case AUDIT_MAKE_EQUIV: {
987                 void *bufp = data;
988                 u32 sizes[2];
989                 size_t msglen = nlmsg_len(nlh);
990                 char *old, *new;
991 
992                 err = -EINVAL;
993                 if (msglen < 2 * sizeof(u32))
994                         break;
995                 memcpy(sizes, bufp, 2 * sizeof(u32));
996                 bufp += 2 * sizeof(u32);
997                 msglen -= 2 * sizeof(u32);
998                 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
999                 if (IS_ERR(old)) {
1000                         err = PTR_ERR(old);
1001                         break;
1002                 }
1003                 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1004                 if (IS_ERR(new)) {
1005                         err = PTR_ERR(new);
1006                         kfree(old);
1007                         break;
1008                 }
1009                 /* OK, here comes... */
1010                 err = audit_tag_tree(old, new);
1011 
1012                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1013 
1014                 audit_log_format(ab, " op=make_equiv old=");
1015                 audit_log_untrustedstring(ab, old);
1016                 audit_log_format(ab, " new=");
1017                 audit_log_untrustedstring(ab, new);
1018                 audit_log_format(ab, " res=%d", !err);
1019                 audit_log_end(ab);
1020                 kfree(old);
1021                 kfree(new);
1022                 break;
1023         }
1024         case AUDIT_SIGNAL_INFO:
1025                 len = 0;
1026                 if (audit_sig_sid) {
1027                         err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1028                         if (err)
1029                                 return err;
1030                 }
1031                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1032                 if (!sig_data) {
1033                         if (audit_sig_sid)
1034                                 security_release_secctx(ctx, len);
1035                         return -ENOMEM;
1036                 }
1037                 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1038                 sig_data->pid = audit_sig_pid;
1039                 if (audit_sig_sid) {
1040                         memcpy(sig_data->ctx, ctx, len);
1041                         security_release_secctx(ctx, len);
1042                 }
1043                 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1044                                  sig_data, sizeof(*sig_data) + len);
1045                 kfree(sig_data);
1046                 break;
1047         case AUDIT_TTY_GET: {
1048                 struct audit_tty_status s;
1049                 unsigned int t;
1050 
1051                 t = READ_ONCE(current->signal->audit_tty);
1052                 s.enabled = t & AUDIT_TTY_ENABLE;
1053                 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1054 
1055                 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1056                 break;
1057         }
1058         case AUDIT_TTY_SET: {
1059                 struct audit_tty_status s, old;
1060                 struct audit_buffer     *ab;
1061                 unsigned int t;
1062 
1063                 memset(&s, 0, sizeof(s));
1064                 /* guard against past and future API changes */
1065                 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1066                 /* check if new data is valid */
1067                 if ((s.enabled != 0 && s.enabled != 1) ||
1068                     (s.log_passwd != 0 && s.log_passwd != 1))
1069                         err = -EINVAL;
1070 
1071                 if (err)
1072                         t = READ_ONCE(current->signal->audit_tty);
1073                 else {
1074                         t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1075                         t = xchg(&current->signal->audit_tty, t);
1076                 }
1077                 old.enabled = t & AUDIT_TTY_ENABLE;
1078                 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1079 
1080                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1081                 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1082                                  " old-log_passwd=%d new-log_passwd=%d res=%d",
1083                                  old.enabled, s.enabled, old.log_passwd,
1084                                  s.log_passwd, !err);
1085                 audit_log_end(ab);
1086                 break;
1087         }
1088         default:
1089                 err = -EINVAL;
1090                 break;
1091         }
1092 
1093         return err < 0 ? err : 0;
1094 }
1095 
1096 /*
1097  * Get message from skb.  Each message is processed by audit_receive_msg.
1098  * Malformed skbs with wrong length are discarded silently.
1099  */
1100 static void audit_receive_skb(struct sk_buff *skb)
1101 {
1102         struct nlmsghdr *nlh;
1103         /*
1104          * len MUST be signed for nlmsg_next to be able to dec it below 0
1105          * if the nlmsg_len was not aligned
1106          */
1107         int len;
1108         int err;
1109 
1110         nlh = nlmsg_hdr(skb);
1111         len = skb->len;
1112 
1113         while (nlmsg_ok(nlh, len)) {
1114                 err = audit_receive_msg(skb, nlh);
1115                 /* if err or if this message says it wants a response */
1116                 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1117                         netlink_ack(skb, nlh, err);
1118 
1119                 nlh = nlmsg_next(nlh, &len);
1120         }
1121 }
1122 
1123 /* Receive messages from netlink socket. */
1124 static void audit_receive(struct sk_buff  *skb)
1125 {
1126         mutex_lock(&audit_cmd_mutex);
1127         audit_receive_skb(skb);
1128         mutex_unlock(&audit_cmd_mutex);
1129 }
1130 
1131 /* Run custom bind function on netlink socket group connect or bind requests. */
1132 static int audit_bind(struct net *net, int group)
1133 {
1134         if (!capable(CAP_AUDIT_READ))
1135                 return -EPERM;
1136 
1137         return 0;
1138 }
1139 
1140 static int __net_init audit_net_init(struct net *net)
1141 {
1142         struct netlink_kernel_cfg cfg = {
1143                 .input  = audit_receive,
1144                 .bind   = audit_bind,
1145                 .flags  = NL_CFG_F_NONROOT_RECV,
1146                 .groups = AUDIT_NLGRP_MAX,
1147         };
1148 
1149         struct audit_net *aunet = net_generic(net, audit_net_id);
1150 
1151         aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1152         if (aunet->nlsk == NULL) {
1153                 audit_panic("cannot initialize netlink socket in namespace");
1154                 return -ENOMEM;
1155         }
1156         aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1157         return 0;
1158 }
1159 
1160 static void __net_exit audit_net_exit(struct net *net)
1161 {
1162         struct audit_net *aunet = net_generic(net, audit_net_id);
1163         struct sock *sock = aunet->nlsk;
1164         if (sock == audit_sock) {
1165                 audit_pid = 0;
1166                 audit_sock = NULL;
1167         }
1168 
1169         RCU_INIT_POINTER(aunet->nlsk, NULL);
1170         synchronize_net();
1171         netlink_kernel_release(sock);
1172 }
1173 
1174 static struct pernet_operations audit_net_ops __net_initdata = {
1175         .init = audit_net_init,
1176         .exit = audit_net_exit,
1177         .id = &audit_net_id,
1178         .size = sizeof(struct audit_net),
1179 };
1180 
1181 /* Initialize audit support at boot time. */
1182 static int __init audit_init(void)
1183 {
1184         int i;
1185 
1186         if (audit_initialized == AUDIT_DISABLED)
1187                 return 0;
1188 
1189         pr_info("initializing netlink subsys (%s)\n",
1190                 audit_default ? "enabled" : "disabled");
1191         register_pernet_subsys(&audit_net_ops);
1192 
1193         skb_queue_head_init(&audit_skb_queue);
1194         skb_queue_head_init(&audit_skb_hold_queue);
1195         audit_initialized = AUDIT_INITIALIZED;
1196         audit_enabled = audit_default;
1197         audit_ever_enabled |= !!audit_default;
1198 
1199         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
1200 
1201         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1202                 INIT_LIST_HEAD(&audit_inode_hash[i]);
1203 
1204         return 0;
1205 }
1206 __initcall(audit_init);
1207 
1208 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
1209 static int __init audit_enable(char *str)
1210 {
1211         audit_default = !!simple_strtol(str, NULL, 0);
1212         if (!audit_default)
1213                 audit_initialized = AUDIT_DISABLED;
1214 
1215         pr_info("%s\n", audit_default ?
1216                 "enabled (after initialization)" : "disabled (until reboot)");
1217 
1218         return 1;
1219 }
1220 __setup("audit=", audit_enable);
1221 
1222 /* Process kernel command-line parameter at boot time.
1223  * audit_backlog_limit=<n> */
1224 static int __init audit_backlog_limit_set(char *str)
1225 {
1226         u32 audit_backlog_limit_arg;
1227 
1228         pr_info("audit_backlog_limit: ");
1229         if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1230                 pr_cont("using default of %u, unable to parse %s\n",
1231                         audit_backlog_limit, str);
1232                 return 1;
1233         }
1234 
1235         audit_backlog_limit = audit_backlog_limit_arg;
1236         pr_cont("%d\n", audit_backlog_limit);
1237 
1238         return 1;
1239 }
1240 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1241 
1242 static void audit_buffer_free(struct audit_buffer *ab)
1243 {
1244         unsigned long flags;
1245 
1246         if (!ab)
1247                 return;
1248 
1249         kfree_skb(ab->skb);
1250         spin_lock_irqsave(&audit_freelist_lock, flags);
1251         if (audit_freelist_count > AUDIT_MAXFREE)
1252                 kfree(ab);
1253         else {
1254                 audit_freelist_count++;
1255                 list_add(&ab->list, &audit_freelist);
1256         }
1257         spin_unlock_irqrestore(&audit_freelist_lock, flags);
1258 }
1259 
1260 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1261                                                 gfp_t gfp_mask, int type)
1262 {
1263         unsigned long flags;
1264         struct audit_buffer *ab = NULL;
1265         struct nlmsghdr *nlh;
1266 
1267         spin_lock_irqsave(&audit_freelist_lock, flags);
1268         if (!list_empty(&audit_freelist)) {
1269                 ab = list_entry(audit_freelist.next,
1270                                 struct audit_buffer, list);
1271                 list_del(&ab->list);
1272                 --audit_freelist_count;
1273         }
1274         spin_unlock_irqrestore(&audit_freelist_lock, flags);
1275 
1276         if (!ab) {
1277                 ab = kmalloc(sizeof(*ab), gfp_mask);
1278                 if (!ab)
1279                         goto err;
1280         }
1281 
1282         ab->ctx = ctx;
1283         ab->gfp_mask = gfp_mask;
1284 
1285         ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1286         if (!ab->skb)
1287                 goto err;
1288 
1289         nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1290         if (!nlh)
1291                 goto out_kfree_skb;
1292 
1293         return ab;
1294 
1295 out_kfree_skb:
1296         kfree_skb(ab->skb);
1297         ab->skb = NULL;
1298 err:
1299         audit_buffer_free(ab);
1300         return NULL;
1301 }
1302 
1303 /**
1304  * audit_serial - compute a serial number for the audit record
1305  *
1306  * Compute a serial number for the audit record.  Audit records are
1307  * written to user-space as soon as they are generated, so a complete
1308  * audit record may be written in several pieces.  The timestamp of the
1309  * record and this serial number are used by the user-space tools to
1310  * determine which pieces belong to the same audit record.  The
1311  * (timestamp,serial) tuple is unique for each syscall and is live from
1312  * syscall entry to syscall exit.
1313  *
1314  * NOTE: Another possibility is to store the formatted records off the
1315  * audit context (for those records that have a context), and emit them
1316  * all at syscall exit.  However, this could delay the reporting of
1317  * significant errors until syscall exit (or never, if the system
1318  * halts).
1319  */
1320 unsigned int audit_serial(void)
1321 {
1322         static atomic_t serial = ATOMIC_INIT(0);
1323 
1324         return atomic_add_return(1, &serial);
1325 }
1326 
1327 static inline void audit_get_stamp(struct audit_context *ctx,
1328                                    struct timespec *t, unsigned int *serial)
1329 {
1330         if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1331                 *t = CURRENT_TIME;
1332                 *serial = audit_serial();
1333         }
1334 }
1335 
1336 /*
1337  * Wait for auditd to drain the queue a little
1338  */
1339 static long wait_for_auditd(long sleep_time)
1340 {
1341         DECLARE_WAITQUEUE(wait, current);
1342 
1343         if (audit_backlog_limit &&
1344             skb_queue_len(&audit_skb_queue) > audit_backlog_limit) {
1345                 add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1346                 set_current_state(TASK_UNINTERRUPTIBLE);
1347                 sleep_time = schedule_timeout(sleep_time);
1348                 remove_wait_queue(&audit_backlog_wait, &wait);
1349         }
1350 
1351         return sleep_time;
1352 }
1353 
1354 /**
1355  * audit_log_start - obtain an audit buffer
1356  * @ctx: audit_context (may be NULL)
1357  * @gfp_mask: type of allocation
1358  * @type: audit message type
1359  *
1360  * Returns audit_buffer pointer on success or NULL on error.
1361  *
1362  * Obtain an audit buffer.  This routine does locking to obtain the
1363  * audit buffer, but then no locking is required for calls to
1364  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1365  * syscall, then the syscall is marked as auditable and an audit record
1366  * will be written at syscall exit.  If there is no associated task, then
1367  * task context (ctx) should be NULL.
1368  */
1369 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1370                                      int type)
1371 {
1372         struct audit_buffer     *ab     = NULL;
1373         struct timespec         t;
1374         unsigned int            uninitialized_var(serial);
1375         int reserve = 5; /* Allow atomic callers to go up to five
1376                             entries over the normal backlog limit */
1377         unsigned long timeout_start = jiffies;
1378 
1379         if (audit_initialized != AUDIT_INITIALIZED)
1380                 return NULL;
1381 
1382         if (unlikely(!audit_filter(type, AUDIT_FILTER_TYPE)))
1383                 return NULL;
1384 
1385         if (gfp_mask & __GFP_DIRECT_RECLAIM) {
1386                 if (audit_pid && audit_pid == current->tgid)
1387                         gfp_mask &= ~__GFP_DIRECT_RECLAIM;
1388                 else
1389                         reserve = 0;
1390         }
1391 
1392         while (audit_backlog_limit
1393                && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1394                 if (gfp_mask & __GFP_DIRECT_RECLAIM && audit_backlog_wait_time) {
1395                         long sleep_time;
1396 
1397                         sleep_time = timeout_start + audit_backlog_wait_time - jiffies;
1398                         if (sleep_time > 0) {
1399                                 sleep_time = wait_for_auditd(sleep_time);
1400                                 if (sleep_time > 0)
1401                                         continue;
1402                         }
1403                 }
1404                 if (audit_rate_check() && printk_ratelimit())
1405                         pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1406                                 skb_queue_len(&audit_skb_queue),
1407                                 audit_backlog_limit);
1408                 audit_log_lost("backlog limit exceeded");
1409                 audit_backlog_wait_time = 0;
1410                 wake_up(&audit_backlog_wait);
1411                 return NULL;
1412         }
1413 
1414         if (!reserve && !audit_backlog_wait_time)
1415                 audit_backlog_wait_time = audit_backlog_wait_time_master;
1416 
1417         ab = audit_buffer_alloc(ctx, gfp_mask, type);
1418         if (!ab) {
1419                 audit_log_lost("out of memory in audit_log_start");
1420                 return NULL;
1421         }
1422 
1423         audit_get_stamp(ab->ctx, &t, &serial);
1424 
1425         audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1426                          t.tv_sec, t.tv_nsec/1000000, serial);
1427         return ab;
1428 }
1429 
1430 /**
1431  * audit_expand - expand skb in the audit buffer
1432  * @ab: audit_buffer
1433  * @extra: space to add at tail of the skb
1434  *
1435  * Returns 0 (no space) on failed expansion, or available space if
1436  * successful.
1437  */
1438 static inline int audit_expand(struct audit_buffer *ab, int extra)
1439 {
1440         struct sk_buff *skb = ab->skb;
1441         int oldtail = skb_tailroom(skb);
1442         int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1443         int newtail = skb_tailroom(skb);
1444 
1445         if (ret < 0) {
1446                 audit_log_lost("out of memory in audit_expand");
1447                 return 0;
1448         }
1449 
1450         skb->truesize += newtail - oldtail;
1451         return newtail;
1452 }
1453 
1454 /*
1455  * Format an audit message into the audit buffer.  If there isn't enough
1456  * room in the audit buffer, more room will be allocated and vsnprint
1457  * will be called a second time.  Currently, we assume that a printk
1458  * can't format message larger than 1024 bytes, so we don't either.
1459  */
1460 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1461                               va_list args)
1462 {
1463         int len, avail;
1464         struct sk_buff *skb;
1465         va_list args2;
1466 
1467         if (!ab)
1468                 return;
1469 
1470         BUG_ON(!ab->skb);
1471         skb = ab->skb;
1472         avail = skb_tailroom(skb);
1473         if (avail == 0) {
1474                 avail = audit_expand(ab, AUDIT_BUFSIZ);
1475                 if (!avail)
1476                         goto out;
1477         }
1478         va_copy(args2, args);
1479         len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1480         if (len >= avail) {
1481                 /* The printk buffer is 1024 bytes long, so if we get
1482                  * here and AUDIT_BUFSIZ is at least 1024, then we can
1483                  * log everything that printk could have logged. */
1484                 avail = audit_expand(ab,
1485                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1486                 if (!avail)
1487                         goto out_va_end;
1488                 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1489         }
1490         if (len > 0)
1491                 skb_put(skb, len);
1492 out_va_end:
1493         va_end(args2);
1494 out:
1495         return;
1496 }
1497 
1498 /**
1499  * audit_log_format - format a message into the audit buffer.
1500  * @ab: audit_buffer
1501  * @fmt: format string
1502  * @...: optional parameters matching @fmt string
1503  *
1504  * All the work is done in audit_log_vformat.
1505  */
1506 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1507 {
1508         va_list args;
1509 
1510         if (!ab)
1511                 return;
1512         va_start(args, fmt);
1513         audit_log_vformat(ab, fmt, args);
1514         va_end(args);
1515 }
1516 
1517 /**
1518  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1519  * @ab: the audit_buffer
1520  * @buf: buffer to convert to hex
1521  * @len: length of @buf to be converted
1522  *
1523  * No return value; failure to expand is silently ignored.
1524  *
1525  * This function will take the passed buf and convert it into a string of
1526  * ascii hex digits. The new string is placed onto the skb.
1527  */
1528 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1529                 size_t len)
1530 {
1531         int i, avail, new_len;
1532         unsigned char *ptr;
1533         struct sk_buff *skb;
1534 
1535         if (!ab)
1536                 return;
1537 
1538         BUG_ON(!ab->skb);
1539         skb = ab->skb;
1540         avail = skb_tailroom(skb);
1541         new_len = len<<1;
1542         if (new_len >= avail) {
1543                 /* Round the buffer request up to the next multiple */
1544                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1545                 avail = audit_expand(ab, new_len);
1546                 if (!avail)
1547                         return;
1548         }
1549 
1550         ptr = skb_tail_pointer(skb);
1551         for (i = 0; i < len; i++)
1552                 ptr = hex_byte_pack_upper(ptr, buf[i]);
1553         *ptr = 0;
1554         skb_put(skb, len << 1); /* new string is twice the old string */
1555 }
1556 
1557 /*
1558  * Format a string of no more than slen characters into the audit buffer,
1559  * enclosed in quote marks.
1560  */
1561 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1562                         size_t slen)
1563 {
1564         int avail, new_len;
1565         unsigned char *ptr;
1566         struct sk_buff *skb;
1567 
1568         if (!ab)
1569                 return;
1570 
1571         BUG_ON(!ab->skb);
1572         skb = ab->skb;
1573         avail = skb_tailroom(skb);
1574         new_len = slen + 3;     /* enclosing quotes + null terminator */
1575         if (new_len > avail) {
1576                 avail = audit_expand(ab, new_len);
1577                 if (!avail)
1578                         return;
1579         }
1580         ptr = skb_tail_pointer(skb);
1581         *ptr++ = '"';
1582         memcpy(ptr, string, slen);
1583         ptr += slen;
1584         *ptr++ = '"';
1585         *ptr = 0;
1586         skb_put(skb, slen + 2); /* don't include null terminator */
1587 }
1588 
1589 /**
1590  * audit_string_contains_control - does a string need to be logged in hex
1591  * @string: string to be checked
1592  * @len: max length of the string to check
1593  */
1594 bool audit_string_contains_control(const char *string, size_t len)
1595 {
1596         const unsigned char *p;
1597         for (p = string; p < (const unsigned char *)string + len; p++) {
1598                 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1599                         return true;
1600         }
1601         return false;
1602 }
1603 
1604 /**
1605  * audit_log_n_untrustedstring - log a string that may contain random characters
1606  * @ab: audit_buffer
1607  * @len: length of string (not including trailing null)
1608  * @string: string to be logged
1609  *
1610  * This code will escape a string that is passed to it if the string
1611  * contains a control character, unprintable character, double quote mark,
1612  * or a space. Unescaped strings will start and end with a double quote mark.
1613  * Strings that are escaped are printed in hex (2 digits per char).
1614  *
1615  * The caller specifies the number of characters in the string to log, which may
1616  * or may not be the entire string.
1617  */
1618 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1619                                  size_t len)
1620 {
1621         if (audit_string_contains_control(string, len))
1622                 audit_log_n_hex(ab, string, len);
1623         else
1624                 audit_log_n_string(ab, string, len);
1625 }
1626 
1627 /**
1628  * audit_log_untrustedstring - log a string that may contain random characters
1629  * @ab: audit_buffer
1630  * @string: string to be logged
1631  *
1632  * Same as audit_log_n_untrustedstring(), except that strlen is used to
1633  * determine string length.
1634  */
1635 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1636 {
1637         audit_log_n_untrustedstring(ab, string, strlen(string));
1638 }
1639 
1640 /* This is a helper-function to print the escaped d_path */
1641 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1642                       const struct path *path)
1643 {
1644         char *p, *pathname;
1645 
1646         if (prefix)
1647                 audit_log_format(ab, "%s", prefix);
1648 
1649         /* We will allow 11 spaces for ' (deleted)' to be appended */
1650         pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1651         if (!pathname) {
1652                 audit_log_string(ab, "<no_memory>");
1653                 return;
1654         }
1655         p = d_path(path, pathname, PATH_MAX+11);
1656         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1657                 /* FIXME: can we save some information here? */
1658                 audit_log_string(ab, "<too_long>");
1659         } else
1660                 audit_log_untrustedstring(ab, p);
1661         kfree(pathname);
1662 }
1663 
1664 void audit_log_session_info(struct audit_buffer *ab)
1665 {
1666         unsigned int sessionid = audit_get_sessionid(current);
1667         uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1668 
1669         audit_log_format(ab, " auid=%u ses=%u", auid, sessionid);
1670 }
1671 
1672 void audit_log_key(struct audit_buffer *ab, char *key)
1673 {
1674         audit_log_format(ab, " key=");
1675         if (key)
1676                 audit_log_untrustedstring(ab, key);
1677         else
1678                 audit_log_format(ab, "(null)");
1679 }
1680 
1681 void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1682 {
1683         int i;
1684 
1685         audit_log_format(ab, " %s=", prefix);
1686         CAP_FOR_EACH_U32(i) {
1687                 audit_log_format(ab, "%08x",
1688                                  cap->cap[CAP_LAST_U32 - i]);
1689         }
1690 }
1691 
1692 static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1693 {
1694         kernel_cap_t *perm = &name->fcap.permitted;
1695         kernel_cap_t *inh = &name->fcap.inheritable;
1696         int log = 0;
1697 
1698         if (!cap_isclear(*perm)) {
1699                 audit_log_cap(ab, "cap_fp", perm);
1700                 log = 1;
1701         }
1702         if (!cap_isclear(*inh)) {
1703                 audit_log_cap(ab, "cap_fi", inh);
1704                 log = 1;
1705         }
1706 
1707         if (log)
1708                 audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1709                                  name->fcap.fE, name->fcap_ver);
1710 }
1711 
1712 static inline int audit_copy_fcaps(struct audit_names *name,
1713                                    const struct dentry *dentry)
1714 {
1715         struct cpu_vfs_cap_data caps;
1716         int rc;
1717 
1718         if (!dentry)
1719                 return 0;
1720 
1721         rc = get_vfs_caps_from_disk(dentry, &caps);
1722         if (rc)
1723                 return rc;
1724 
1725         name->fcap.permitted = caps.permitted;
1726         name->fcap.inheritable = caps.inheritable;
1727         name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1728         name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1729                                 VFS_CAP_REVISION_SHIFT;
1730 
1731         return 0;
1732 }
1733 
1734 /* Copy inode data into an audit_names. */
1735 void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1736                       struct inode *inode)
1737 {
1738         name->ino   = inode->i_ino;
1739         name->dev   = inode->i_sb->s_dev;
1740         name->mode  = inode->i_mode;
1741         name->uid   = inode->i_uid;
1742         name->gid   = inode->i_gid;
1743         name->rdev  = inode->i_rdev;
1744         security_inode_getsecid(inode, &name->osid);
1745         audit_copy_fcaps(name, dentry);
1746 }
1747 
1748 /**
1749  * audit_log_name - produce AUDIT_PATH record from struct audit_names
1750  * @context: audit_context for the task
1751  * @n: audit_names structure with reportable details
1752  * @path: optional path to report instead of audit_names->name
1753  * @record_num: record number to report when handling a list of names
1754  * @call_panic: optional pointer to int that will be updated if secid fails
1755  */
1756 void audit_log_name(struct audit_context *context, struct audit_names *n,
1757                     struct path *path, int record_num, int *call_panic)
1758 {
1759         struct audit_buffer *ab;
1760         ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1761         if (!ab)
1762                 return;
1763 
1764         audit_log_format(ab, "item=%d", record_num);
1765 
1766         if (path)
1767                 audit_log_d_path(ab, " name=", path);
1768         else if (n->name) {
1769                 switch (n->name_len) {
1770                 case AUDIT_NAME_FULL:
1771                         /* log the full path */
1772                         audit_log_format(ab, " name=");
1773                         audit_log_untrustedstring(ab, n->name->name);
1774                         break;
1775                 case 0:
1776                         /* name was specified as a relative path and the
1777                          * directory component is the cwd */
1778                         audit_log_d_path(ab, " name=", &context->pwd);
1779                         break;
1780                 default:
1781                         /* log the name's directory component */
1782                         audit_log_format(ab, " name=");
1783                         audit_log_n_untrustedstring(ab, n->name->name,
1784                                                     n->name_len);
1785                 }
1786         } else
1787                 audit_log_format(ab, " name=(null)");
1788 
1789         if (n->ino != AUDIT_INO_UNSET)
1790                 audit_log_format(ab, " inode=%lu"
1791                                  " dev=%02x:%02x mode=%#ho"
1792                                  " ouid=%u ogid=%u rdev=%02x:%02x",
1793                                  n->ino,
1794                                  MAJOR(n->dev),
1795                                  MINOR(n->dev),
1796                                  n->mode,
1797                                  from_kuid(&init_user_ns, n->uid),
1798                                  from_kgid(&init_user_ns, n->gid),
1799                                  MAJOR(n->rdev),
1800                                  MINOR(n->rdev));
1801         if (n->osid != 0) {
1802                 char *ctx = NULL;
1803                 u32 len;
1804                 if (security_secid_to_secctx(
1805                         n->osid, &ctx, &len)) {
1806                         audit_log_format(ab, " osid=%u", n->osid);
1807                         if (call_panic)
1808                                 *call_panic = 2;
1809                 } else {
1810                         audit_log_format(ab, " obj=%s", ctx);
1811                         security_release_secctx(ctx, len);
1812                 }
1813         }
1814 
1815         /* log the audit_names record type */
1816         audit_log_format(ab, " nametype=");
1817         switch(n->type) {
1818         case AUDIT_TYPE_NORMAL:
1819                 audit_log_format(ab, "NORMAL");
1820                 break;
1821         case AUDIT_TYPE_PARENT:
1822                 audit_log_format(ab, "PARENT");
1823                 break;
1824         case AUDIT_TYPE_CHILD_DELETE:
1825                 audit_log_format(ab, "DELETE");
1826                 break;
1827         case AUDIT_TYPE_CHILD_CREATE:
1828                 audit_log_format(ab, "CREATE");
1829                 break;
1830         default:
1831                 audit_log_format(ab, "UNKNOWN");
1832                 break;
1833         }
1834 
1835         audit_log_fcaps(ab, n);
1836         audit_log_end(ab);
1837 }
1838 
1839 int audit_log_task_context(struct audit_buffer *ab)
1840 {
1841         char *ctx = NULL;
1842         unsigned len;
1843         int error;
1844         u32 sid;
1845 
1846         security_task_getsecid(current, &sid);
1847         if (!sid)
1848                 return 0;
1849 
1850         error = security_secid_to_secctx(sid, &ctx, &len);
1851         if (error) {
1852                 if (error != -EINVAL)
1853                         goto error_path;
1854                 return 0;
1855         }
1856 
1857         audit_log_format(ab, " subj=%s", ctx);
1858         security_release_secctx(ctx, len);
1859         return 0;
1860 
1861 error_path:
1862         audit_panic("error in audit_log_task_context");
1863         return error;
1864 }
1865 EXPORT_SYMBOL(audit_log_task_context);
1866 
1867 void audit_log_d_path_exe(struct audit_buffer *ab,
1868                           struct mm_struct *mm)
1869 {
1870         struct file *exe_file;
1871 
1872         if (!mm)
1873                 goto out_null;
1874 
1875         exe_file = get_mm_exe_file(mm);
1876         if (!exe_file)
1877                 goto out_null;
1878 
1879         audit_log_d_path(ab, " exe=", &exe_file->f_path);
1880         fput(exe_file);
1881         return;
1882 out_null:
1883         audit_log_format(ab, " exe=(null)");
1884 }
1885 
1886 struct tty_struct *audit_get_tty(struct task_struct *tsk)
1887 {
1888         struct tty_struct *tty = NULL;
1889         unsigned long flags;
1890 
1891         spin_lock_irqsave(&tsk->sighand->siglock, flags);
1892         if (tsk->signal)
1893                 tty = tty_kref_get(tsk->signal->tty);
1894         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
1895         return tty;
1896 }
1897 
1898 void audit_put_tty(struct tty_struct *tty)
1899 {
1900         tty_kref_put(tty);
1901 }
1902 
1903 void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
1904 {
1905         const struct cred *cred;
1906         char comm[sizeof(tsk->comm)];
1907         struct tty_struct *tty;
1908 
1909         if (!ab)
1910                 return;
1911 
1912         /* tsk == current */
1913         cred = current_cred();
1914         tty = audit_get_tty(tsk);
1915         audit_log_format(ab,
1916                          " ppid=%d pid=%d auid=%u uid=%u gid=%u"
1917                          " euid=%u suid=%u fsuid=%u"
1918                          " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
1919                          task_ppid_nr(tsk),
1920                          task_pid_nr(tsk),
1921                          from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
1922                          from_kuid(&init_user_ns, cred->uid),
1923                          from_kgid(&init_user_ns, cred->gid),
1924                          from_kuid(&init_user_ns, cred->euid),
1925                          from_kuid(&init_user_ns, cred->suid),
1926                          from_kuid(&init_user_ns, cred->fsuid),
1927                          from_kgid(&init_user_ns, cred->egid),
1928                          from_kgid(&init_user_ns, cred->sgid),
1929                          from_kgid(&init_user_ns, cred->fsgid),
1930                          tty ? tty_name(tty) : "(none)",
1931                          audit_get_sessionid(tsk));
1932         audit_put_tty(tty);
1933         audit_log_format(ab, " comm=");
1934         audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
1935         audit_log_d_path_exe(ab, tsk->mm);
1936         audit_log_task_context(ab);
1937 }
1938 EXPORT_SYMBOL(audit_log_task_info);
1939 
1940 /**
1941  * audit_log_link_denied - report a link restriction denial
1942  * @operation: specific link operation
1943  * @link: the path that triggered the restriction
1944  */
1945 void audit_log_link_denied(const char *operation, struct path *link)
1946 {
1947         struct audit_buffer *ab;
1948         struct audit_names *name;
1949 
1950         name = kzalloc(sizeof(*name), GFP_NOFS);
1951         if (!name)
1952                 return;
1953 
1954         /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
1955         ab = audit_log_start(current->audit_context, GFP_KERNEL,
1956                              AUDIT_ANOM_LINK);
1957         if (!ab)
1958                 goto out;
1959         audit_log_format(ab, "op=%s", operation);
1960         audit_log_task_info(ab, current);
1961         audit_log_format(ab, " res=0");
1962         audit_log_end(ab);
1963 
1964         /* Generate AUDIT_PATH record with object. */
1965         name->type = AUDIT_TYPE_NORMAL;
1966         audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
1967         audit_log_name(current->audit_context, name, link, 0, NULL);
1968 out:
1969         kfree(name);
1970 }
1971 
1972 /**
1973  * audit_log_end - end one audit record
1974  * @ab: the audit_buffer
1975  *
1976  * netlink_unicast() cannot be called inside an irq context because it blocks
1977  * (last arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed
1978  * on a queue and a tasklet is scheduled to remove them from the queue outside
1979  * the irq context.  May be called in any context.
1980  */
1981 void audit_log_end(struct audit_buffer *ab)
1982 {
1983         if (!ab)
1984                 return;
1985         if (!audit_rate_check()) {
1986                 audit_log_lost("rate limit exceeded");
1987         } else {
1988                 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1989 
1990                 nlh->nlmsg_len = ab->skb->len;
1991                 kauditd_send_multicast_skb(ab->skb, ab->gfp_mask);
1992 
1993                 /*
1994                  * The original kaudit unicast socket sends up messages with
1995                  * nlmsg_len set to the payload length rather than the entire
1996                  * message length.  This breaks the standard set by netlink.
1997                  * The existing auditd daemon assumes this breakage.  Fixing
1998                  * this would require co-ordinating a change in the established
1999                  * protocol between the kaudit kernel subsystem and the auditd
2000                  * userspace code.
2001                  */
2002                 nlh->nlmsg_len -= NLMSG_HDRLEN;
2003 
2004                 if (audit_pid) {
2005                         skb_queue_tail(&audit_skb_queue, ab->skb);
2006                         wake_up_interruptible(&kauditd_wait);
2007                 } else {
2008                         audit_printk_skb(ab->skb);
2009                 }
2010                 ab->skb = NULL;
2011         }
2012         audit_buffer_free(ab);
2013 }
2014 
2015 /**
2016  * audit_log - Log an audit record
2017  * @ctx: audit context
2018  * @gfp_mask: type of allocation
2019  * @type: audit message type
2020  * @fmt: format string to use
2021  * @...: variable parameters matching the format string
2022  *
2023  * This is a convenience function that calls audit_log_start,
2024  * audit_log_vformat, and audit_log_end.  It may be called
2025  * in any context.
2026  */
2027 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2028                const char *fmt, ...)
2029 {
2030         struct audit_buffer *ab;
2031         va_list args;
2032 
2033         ab = audit_log_start(ctx, gfp_mask, type);
2034         if (ab) {
2035                 va_start(args, fmt);
2036                 audit_log_vformat(ab, fmt, args);
2037                 va_end(args);
2038                 audit_log_end(ab);
2039         }
2040 }
2041 
2042 #ifdef CONFIG_SECURITY
2043 /**
2044  * audit_log_secctx - Converts and logs SELinux context
2045  * @ab: audit_buffer
2046  * @secid: security number
2047  *
2048  * This is a helper function that calls security_secid_to_secctx to convert
2049  * secid to secctx and then adds the (converted) SELinux context to the audit
2050  * log by calling audit_log_format, thus also preventing leak of internal secid
2051  * to userspace. If secid cannot be converted audit_panic is called.
2052  */
2053 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
2054 {
2055         u32 len;
2056         char *secctx;
2057 
2058         if (security_secid_to_secctx(secid, &secctx, &len)) {
2059                 audit_panic("Cannot convert secid to context");
2060         } else {
2061                 audit_log_format(ab, " obj=%s", secctx);
2062                 security_release_secctx(secctx, len);
2063         }
2064 }
2065 EXPORT_SYMBOL(audit_log_secctx);
2066 #endif
2067 
2068 EXPORT_SYMBOL(audit_log_start);
2069 EXPORT_SYMBOL(audit_log_end);
2070 EXPORT_SYMBOL(audit_log_format);
2071 EXPORT_SYMBOL(audit_log);
2072 

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