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Linux/kernel/audit.c

  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 = AUDIT_BACKLOG_WAIT_TIME;
111 
112 /* The identity of the user shutting down the audit system. */
113 kuid_t          audit_sig_uid = INVALID_UID;
114 pid_t           audit_sig_pid = -1;
115 u32             audit_sig_sid = 0;
116 
117 /* Records can be lost in several ways:
118    0) [suppressed in audit_alloc]
119    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
120    2) out of memory in audit_log_move [alloc_skb]
121    3) suppressed due to audit_rate_limit
122    4) suppressed due to audit_backlog_limit
123 */
124 static atomic_t    audit_lost = ATOMIC_INIT(0);
125 
126 /* The netlink socket. */
127 static struct sock *audit_sock;
128 static unsigned int audit_net_id;
129 
130 /* Hash for inode-based rules */
131 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
132 
133 /* The audit_freelist is a list of pre-allocated audit buffers (if more
134  * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
135  * being placed on the freelist). */
136 static DEFINE_SPINLOCK(audit_freelist_lock);
137 static int         audit_freelist_count;
138 static LIST_HEAD(audit_freelist);
139 
140 /* queue msgs to send via kauditd_task */
141 static struct sk_buff_head audit_queue;
142 /* queue msgs due to temporary unicast send problems */
143 static struct sk_buff_head audit_retry_queue;
144 /* queue msgs waiting for new auditd connection */
145 static struct sk_buff_head audit_hold_queue;
146 
147 /* queue servicing thread */
148 static struct task_struct *kauditd_task;
149 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
150 
151 /* waitqueue for callers who are blocked on the audit backlog */
152 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
153 
154 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
155                                    .mask = -1,
156                                    .features = 0,
157                                    .lock = 0,};
158 
159 static char *audit_feature_names[2] = {
160         "only_unset_loginuid",
161         "loginuid_immutable",
162 };
163 
164 
165 /* Serialize requests from userspace. */
166 DEFINE_MUTEX(audit_cmd_mutex);
167 
168 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
169  * audit records.  Since printk uses a 1024 byte buffer, this buffer
170  * should be at least that large. */
171 #define AUDIT_BUFSIZ 1024
172 
173 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
174  * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
175 #define AUDIT_MAXFREE  (2*NR_CPUS)
176 
177 /* The audit_buffer is used when formatting an audit record.  The caller
178  * locks briefly to get the record off the freelist or to allocate the
179  * buffer, and locks briefly to send the buffer to the netlink layer or
180  * to place it on a transmit queue.  Multiple audit_buffers can be in
181  * use simultaneously. */
182 struct audit_buffer {
183         struct list_head     list;
184         struct sk_buff       *skb;      /* formatted skb ready to send */
185         struct audit_context *ctx;      /* NULL or associated context */
186         gfp_t                gfp_mask;
187 };
188 
189 struct audit_reply {
190         __u32 portid;
191         struct net *net;
192         struct sk_buff *skb;
193 };
194 
195 static void audit_set_portid(struct audit_buffer *ab, __u32 portid)
196 {
197         if (ab) {
198                 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
199                 nlh->nlmsg_pid = portid;
200         }
201 }
202 
203 void audit_panic(const char *message)
204 {
205         switch (audit_failure) {
206         case AUDIT_FAIL_SILENT:
207                 break;
208         case AUDIT_FAIL_PRINTK:
209                 if (printk_ratelimit())
210                         pr_err("%s\n", message);
211                 break;
212         case AUDIT_FAIL_PANIC:
213                 /* test audit_pid since printk is always losey, why bother? */
214                 if (audit_pid)
215                         panic("audit: %s\n", message);
216                 break;
217         }
218 }
219 
220 static inline int audit_rate_check(void)
221 {
222         static unsigned long    last_check = 0;
223         static int              messages   = 0;
224         static DEFINE_SPINLOCK(lock);
225         unsigned long           flags;
226         unsigned long           now;
227         unsigned long           elapsed;
228         int                     retval     = 0;
229 
230         if (!audit_rate_limit) return 1;
231 
232         spin_lock_irqsave(&lock, flags);
233         if (++messages < audit_rate_limit) {
234                 retval = 1;
235         } else {
236                 now     = jiffies;
237                 elapsed = now - last_check;
238                 if (elapsed > HZ) {
239                         last_check = now;
240                         messages   = 0;
241                         retval     = 1;
242                 }
243         }
244         spin_unlock_irqrestore(&lock, flags);
245 
246         return retval;
247 }
248 
249 /**
250  * audit_log_lost - conditionally log lost audit message event
251  * @message: the message stating reason for lost audit message
252  *
253  * Emit at least 1 message per second, even if audit_rate_check is
254  * throttling.
255  * Always increment the lost messages counter.
256 */
257 void audit_log_lost(const char *message)
258 {
259         static unsigned long    last_msg = 0;
260         static DEFINE_SPINLOCK(lock);
261         unsigned long           flags;
262         unsigned long           now;
263         int                     print;
264 
265         atomic_inc(&audit_lost);
266 
267         print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
268 
269         if (!print) {
270                 spin_lock_irqsave(&lock, flags);
271                 now = jiffies;
272                 if (now - last_msg > HZ) {
273                         print = 1;
274                         last_msg = now;
275                 }
276                 spin_unlock_irqrestore(&lock, flags);
277         }
278 
279         if (print) {
280                 if (printk_ratelimit())
281                         pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
282                                 atomic_read(&audit_lost),
283                                 audit_rate_limit,
284                                 audit_backlog_limit);
285                 audit_panic(message);
286         }
287 }
288 
289 static int audit_log_config_change(char *function_name, u32 new, u32 old,
290                                    int allow_changes)
291 {
292         struct audit_buffer *ab;
293         int rc = 0;
294 
295         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
296         if (unlikely(!ab))
297                 return rc;
298         audit_log_format(ab, "%s=%u old=%u", function_name, new, old);
299         audit_log_session_info(ab);
300         rc = audit_log_task_context(ab);
301         if (rc)
302                 allow_changes = 0; /* Something weird, deny request */
303         audit_log_format(ab, " res=%d", allow_changes);
304         audit_log_end(ab);
305         return rc;
306 }
307 
308 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
309 {
310         int allow_changes, rc = 0;
311         u32 old = *to_change;
312 
313         /* check if we are locked */
314         if (audit_enabled == AUDIT_LOCKED)
315                 allow_changes = 0;
316         else
317                 allow_changes = 1;
318 
319         if (audit_enabled != AUDIT_OFF) {
320                 rc = audit_log_config_change(function_name, new, old, allow_changes);
321                 if (rc)
322                         allow_changes = 0;
323         }
324 
325         /* If we are allowed, make the change */
326         if (allow_changes == 1)
327                 *to_change = new;
328         /* Not allowed, update reason */
329         else if (rc == 0)
330                 rc = -EPERM;
331         return rc;
332 }
333 
334 static int audit_set_rate_limit(u32 limit)
335 {
336         return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
337 }
338 
339 static int audit_set_backlog_limit(u32 limit)
340 {
341         return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
342 }
343 
344 static int audit_set_backlog_wait_time(u32 timeout)
345 {
346         return audit_do_config_change("audit_backlog_wait_time",
347                                       &audit_backlog_wait_time, timeout);
348 }
349 
350 static int audit_set_enabled(u32 state)
351 {
352         int rc;
353         if (state > AUDIT_LOCKED)
354                 return -EINVAL;
355 
356         rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
357         if (!rc)
358                 audit_ever_enabled |= !!state;
359 
360         return rc;
361 }
362 
363 static int audit_set_failure(u32 state)
364 {
365         if (state != AUDIT_FAIL_SILENT
366             && state != AUDIT_FAIL_PRINTK
367             && state != AUDIT_FAIL_PANIC)
368                 return -EINVAL;
369 
370         return audit_do_config_change("audit_failure", &audit_failure, state);
371 }
372 
373 /*
374  * For one reason or another this nlh isn't getting delivered to the userspace
375  * audit daemon, just send it to printk.
376  */
377 static void kauditd_printk_skb(struct sk_buff *skb)
378 {
379         struct nlmsghdr *nlh = nlmsg_hdr(skb);
380         char *data = nlmsg_data(nlh);
381 
382         if (nlh->nlmsg_type != AUDIT_EOE) {
383                 if (printk_ratelimit())
384                         pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
385                 else
386                         audit_log_lost("printk limit exceeded");
387         }
388 }
389 
390 /**
391  * kauditd_hold_skb - Queue an audit record, waiting for auditd
392  * @skb: audit record
393  *
394  * Description:
395  * Queue the audit record, waiting for an instance of auditd.  When this
396  * function is called we haven't given up yet on sending the record, but things
397  * are not looking good.  The first thing we want to do is try to write the
398  * record via printk and then see if we want to try and hold on to the record
399  * and queue it, if we have room.  If we want to hold on to the record, but we
400  * don't have room, record a record lost message.
401  */
402 static void kauditd_hold_skb(struct sk_buff *skb)
403 {
404         /* at this point it is uncertain if we will ever send this to auditd so
405          * try to send the message via printk before we go any further */
406         kauditd_printk_skb(skb);
407 
408         /* can we just silently drop the message? */
409         if (!audit_default) {
410                 kfree_skb(skb);
411                 return;
412         }
413 
414         /* if we have room, queue the message */
415         if (!audit_backlog_limit ||
416             skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
417                 skb_queue_tail(&audit_hold_queue, skb);
418                 return;
419         }
420 
421         /* we have no other options - drop the message */
422         audit_log_lost("kauditd hold queue overflow");
423         kfree_skb(skb);
424 }
425 
426 /**
427  * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
428  * @skb: audit record
429  *
430  * Description:
431  * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
432  * but for some reason we are having problems sending it audit records so
433  * queue the given record and attempt to resend.
434  */
435 static void kauditd_retry_skb(struct sk_buff *skb)
436 {
437         /* NOTE: because records should only live in the retry queue for a
438          * short period of time, before either being sent or moved to the hold
439          * queue, we don't currently enforce a limit on this queue */
440         skb_queue_tail(&audit_retry_queue, skb);
441 }
442 
443 /**
444  * auditd_reset - Disconnect the auditd connection
445  *
446  * Description:
447  * Break the auditd/kauditd connection and move all the records in the retry
448  * queue into the hold queue in case auditd reconnects.  The audit_cmd_mutex
449  * must be held when calling this function.
450  */
451 static void auditd_reset(void)
452 {
453         struct sk_buff *skb;
454 
455         /* break the connection */
456         if (audit_sock) {
457                 sock_put(audit_sock);
458                 audit_sock = NULL;
459         }
460         audit_pid = 0;
461         audit_nlk_portid = 0;
462 
463         /* flush all of the retry queue to the hold queue */
464         while ((skb = skb_dequeue(&audit_retry_queue)))
465                 kauditd_hold_skb(skb);
466 }
467 
468 /**
469  * kauditd_send_unicast_skb - Send a record via unicast to auditd
470  * @skb: audit record
471  */
472 static int kauditd_send_unicast_skb(struct sk_buff *skb)
473 {
474         int rc;
475 
476         /* if we know nothing is connected, don't even try the netlink call */
477         if (!audit_pid)
478                 return -ECONNREFUSED;
479 
480         /* get an extra skb reference in case we fail to send */
481         skb_get(skb);
482         rc = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
483         if (rc >= 0) {
484                 consume_skb(skb);
485                 rc = 0;
486         }
487 
488         return rc;
489 }
490 
491 /*
492  * kauditd_send_multicast_skb - Send a record to any multicast listeners
493  * @skb: audit record
494  *
495  * Description:
496  * This function doesn't consume an skb as might be expected since it has to
497  * copy it anyways.
498  */
499 static void kauditd_send_multicast_skb(struct sk_buff *skb)
500 {
501         struct sk_buff *copy;
502         struct audit_net *aunet = net_generic(&init_net, audit_net_id);
503         struct sock *sock = aunet->nlsk;
504         struct nlmsghdr *nlh;
505 
506         if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
507                 return;
508 
509         /*
510          * The seemingly wasteful skb_copy() rather than bumping the refcount
511          * using skb_get() is necessary because non-standard mods are made to
512          * the skb by the original kaudit unicast socket send routine.  The
513          * existing auditd daemon assumes this breakage.  Fixing this would
514          * require co-ordinating a change in the established protocol between
515          * the kaudit kernel subsystem and the auditd userspace code.  There is
516          * no reason for new multicast clients to continue with this
517          * non-compliance.
518          */
519         copy = skb_copy(skb, GFP_KERNEL);
520         if (!copy)
521                 return;
522         nlh = nlmsg_hdr(copy);
523         nlh->nlmsg_len = skb->len;
524 
525         nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
526 }
527 
528 /**
529  * kauditd_wake_condition - Return true when it is time to wake kauditd_thread
530  *
531  * Description:
532  * This function is for use by the wait_event_freezable() call in
533  * kauditd_thread().
534  */
535 static int kauditd_wake_condition(void)
536 {
537         static int pid_last = 0;
538         int rc;
539         int pid = audit_pid;
540 
541         /* wake on new messages or a change in the connected auditd */
542         rc = skb_queue_len(&audit_queue) || (pid && pid != pid_last);
543         if (rc)
544                 pid_last = pid;
545 
546         return rc;
547 }
548 
549 static int kauditd_thread(void *dummy)
550 {
551         int rc;
552         int auditd = 0;
553         int reschedule = 0;
554         struct sk_buff *skb;
555         struct nlmsghdr *nlh;
556 
557 #define UNICAST_RETRIES 5
558 #define AUDITD_BAD(x,y) \
559         ((x) == -ECONNREFUSED || (x) == -EPERM || ++(y) >= UNICAST_RETRIES)
560 
561         /* NOTE: we do invalidate the auditd connection flag on any sending
562          * errors, but we only "restore" the connection flag at specific places
563          * in the loop in order to help ensure proper ordering of audit
564          * records */
565 
566         set_freezable();
567         while (!kthread_should_stop()) {
568                 /* NOTE: possible area for future improvement is to look at
569                  *       the hold and retry queues, since only this thread
570                  *       has access to these queues we might be able to do
571                  *       our own queuing and skip some/all of the locking */
572 
573                 /* NOTE: it might be a fun experiment to split the hold and
574                  *       retry queue handling to another thread, but the
575                  *       synchronization issues and other overhead might kill
576                  *       any performance gains */
577 
578                 /* attempt to flush the hold queue */
579                 while (auditd && (skb = skb_dequeue(&audit_hold_queue))) {
580                         rc = kauditd_send_unicast_skb(skb);
581                         if (rc) {
582                                 /* requeue to the same spot */
583                                 skb_queue_head(&audit_hold_queue, skb);
584 
585                                 auditd = 0;
586                                 if (AUDITD_BAD(rc, reschedule)) {
587                                         mutex_lock(&audit_cmd_mutex);
588                                         auditd_reset();
589                                         mutex_unlock(&audit_cmd_mutex);
590                                         reschedule = 0;
591                                 }
592                         } else
593                                 /* we were able to send successfully */
594                                 reschedule = 0;
595                 }
596 
597                 /* attempt to flush the retry queue */
598                 while (auditd && (skb = skb_dequeue(&audit_retry_queue))) {
599                         rc = kauditd_send_unicast_skb(skb);
600                         if (rc) {
601                                 auditd = 0;
602                                 if (AUDITD_BAD(rc, reschedule)) {
603                                         kauditd_hold_skb(skb);
604                                         mutex_lock(&audit_cmd_mutex);
605                                         auditd_reset();
606                                         mutex_unlock(&audit_cmd_mutex);
607                                         reschedule = 0;
608                                 } else
609                                         /* temporary problem (we hope), queue
610                                          * to the same spot and retry */
611                                         skb_queue_head(&audit_retry_queue, skb);
612                         } else
613                                 /* we were able to send successfully */
614                                 reschedule = 0;
615                 }
616 
617                 /* standard queue processing, try to be as quick as possible */
618 quick_loop:
619                 skb = skb_dequeue(&audit_queue);
620                 if (skb) {
621                         /* setup the netlink header, see the comments in
622                          * kauditd_send_multicast_skb() for length quirks */
623                         nlh = nlmsg_hdr(skb);
624                         nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
625 
626                         /* attempt to send to any multicast listeners */
627                         kauditd_send_multicast_skb(skb);
628 
629                         /* attempt to send to auditd, queue on failure */
630                         if (auditd) {
631                                 rc = kauditd_send_unicast_skb(skb);
632                                 if (rc) {
633                                         auditd = 0;
634                                         if (AUDITD_BAD(rc, reschedule)) {
635                                                 mutex_lock(&audit_cmd_mutex);
636                                                 auditd_reset();
637                                                 mutex_unlock(&audit_cmd_mutex);
638                                                 reschedule = 0;
639                                         }
640 
641                                         /* move to the retry queue */
642                                         kauditd_retry_skb(skb);
643                                 } else
644                                         /* everything is working so go fast! */
645                                         goto quick_loop;
646                         } else if (reschedule)
647                                 /* we are currently having problems, move to
648                                  * the retry queue */
649                                 kauditd_retry_skb(skb);
650                         else
651                                 /* dump the message via printk and hold it */
652                                 kauditd_hold_skb(skb);
653                 } else {
654                         /* we have flushed the backlog so wake everyone */
655                         wake_up(&audit_backlog_wait);
656 
657                         /* if everything is okay with auditd (if present), go
658                          * to sleep until there is something new in the queue
659                          * or we have a change in the connected auditd;
660                          * otherwise simply reschedule to give things a chance
661                          * to recover */
662                         if (reschedule) {
663                                 set_current_state(TASK_INTERRUPTIBLE);
664                                 schedule();
665                         } else
666                                 wait_event_freezable(kauditd_wait,
667                                                      kauditd_wake_condition());
668 
669                         /* update the auditd connection status */
670                         auditd = (audit_pid ? 1 : 0);
671                 }
672         }
673 
674         return 0;
675 }
676 
677 int audit_send_list(void *_dest)
678 {
679         struct audit_netlink_list *dest = _dest;
680         struct sk_buff *skb;
681         struct net *net = dest->net;
682         struct audit_net *aunet = net_generic(net, audit_net_id);
683 
684         /* wait for parent to finish and send an ACK */
685         mutex_lock(&audit_cmd_mutex);
686         mutex_unlock(&audit_cmd_mutex);
687 
688         while ((skb = __skb_dequeue(&dest->q)) != NULL)
689                 netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
690 
691         put_net(net);
692         kfree(dest);
693 
694         return 0;
695 }
696 
697 struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
698                                  int multi, const void *payload, int size)
699 {
700         struct sk_buff  *skb;
701         struct nlmsghdr *nlh;
702         void            *data;
703         int             flags = multi ? NLM_F_MULTI : 0;
704         int             t     = done  ? NLMSG_DONE  : type;
705 
706         skb = nlmsg_new(size, GFP_KERNEL);
707         if (!skb)
708                 return NULL;
709 
710         nlh     = nlmsg_put(skb, portid, seq, t, size, flags);
711         if (!nlh)
712                 goto out_kfree_skb;
713         data = nlmsg_data(nlh);
714         memcpy(data, payload, size);
715         return skb;
716 
717 out_kfree_skb:
718         kfree_skb(skb);
719         return NULL;
720 }
721 
722 static int audit_send_reply_thread(void *arg)
723 {
724         struct audit_reply *reply = (struct audit_reply *)arg;
725         struct net *net = reply->net;
726         struct audit_net *aunet = net_generic(net, audit_net_id);
727 
728         mutex_lock(&audit_cmd_mutex);
729         mutex_unlock(&audit_cmd_mutex);
730 
731         /* Ignore failure. It'll only happen if the sender goes away,
732            because our timeout is set to infinite. */
733         netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
734         put_net(net);
735         kfree(reply);
736         return 0;
737 }
738 
739 /**
740  * audit_send_reply - send an audit reply message via netlink
741  * @request_skb: skb of request we are replying to (used to target the reply)
742  * @seq: sequence number
743  * @type: audit message type
744  * @done: done (last) flag
745  * @multi: multi-part message flag
746  * @payload: payload data
747  * @size: payload size
748  *
749  * Allocates an skb, builds the netlink message, and sends it to the port id.
750  * No failure notifications.
751  */
752 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
753                              int multi, const void *payload, int size)
754 {
755         u32 portid = NETLINK_CB(request_skb).portid;
756         struct net *net = sock_net(NETLINK_CB(request_skb).sk);
757         struct sk_buff *skb;
758         struct task_struct *tsk;
759         struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
760                                             GFP_KERNEL);
761 
762         if (!reply)
763                 return;
764 
765         skb = audit_make_reply(portid, seq, type, done, multi, payload, size);
766         if (!skb)
767                 goto out;
768 
769         reply->net = get_net(net);
770         reply->portid = portid;
771         reply->skb = skb;
772 
773         tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
774         if (!IS_ERR(tsk))
775                 return;
776         kfree_skb(skb);
777 out:
778         kfree(reply);
779 }
780 
781 /*
782  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
783  * control messages.
784  */
785 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
786 {
787         int err = 0;
788 
789         /* Only support initial user namespace for now. */
790         /*
791          * We return ECONNREFUSED because it tricks userspace into thinking
792          * that audit was not configured into the kernel.  Lots of users
793          * configure their PAM stack (because that's what the distro does)
794          * to reject login if unable to send messages to audit.  If we return
795          * ECONNREFUSED the PAM stack thinks the kernel does not have audit
796          * configured in and will let login proceed.  If we return EPERM
797          * userspace will reject all logins.  This should be removed when we
798          * support non init namespaces!!
799          */
800         if (current_user_ns() != &init_user_ns)
801                 return -ECONNREFUSED;
802 
803         switch (msg_type) {
804         case AUDIT_LIST:
805         case AUDIT_ADD:
806         case AUDIT_DEL:
807                 return -EOPNOTSUPP;
808         case AUDIT_GET:
809         case AUDIT_SET:
810         case AUDIT_GET_FEATURE:
811         case AUDIT_SET_FEATURE:
812         case AUDIT_LIST_RULES:
813         case AUDIT_ADD_RULE:
814         case AUDIT_DEL_RULE:
815         case AUDIT_SIGNAL_INFO:
816         case AUDIT_TTY_GET:
817         case AUDIT_TTY_SET:
818         case AUDIT_TRIM:
819         case AUDIT_MAKE_EQUIV:
820                 /* Only support auditd and auditctl in initial pid namespace
821                  * for now. */
822                 if (task_active_pid_ns(current) != &init_pid_ns)
823                         return -EPERM;
824 
825                 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
826                         err = -EPERM;
827                 break;
828         case AUDIT_USER:
829         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
830         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
831                 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
832                         err = -EPERM;
833                 break;
834         default:  /* bad msg */
835                 err = -EINVAL;
836         }
837 
838         return err;
839 }
840 
841 static void audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
842 {
843         uid_t uid = from_kuid(&init_user_ns, current_uid());
844         pid_t pid = task_tgid_nr(current);
845 
846         if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
847                 *ab = NULL;
848                 return;
849         }
850 
851         *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
852         if (unlikely(!*ab))
853                 return;
854         audit_log_format(*ab, "pid=%d uid=%u", pid, uid);
855         audit_log_session_info(*ab);
856         audit_log_task_context(*ab);
857 }
858 
859 int is_audit_feature_set(int i)
860 {
861         return af.features & AUDIT_FEATURE_TO_MASK(i);
862 }
863 
864 
865 static int audit_get_feature(struct sk_buff *skb)
866 {
867         u32 seq;
868 
869         seq = nlmsg_hdr(skb)->nlmsg_seq;
870 
871         audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
872 
873         return 0;
874 }
875 
876 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
877                                      u32 old_lock, u32 new_lock, int res)
878 {
879         struct audit_buffer *ab;
880 
881         if (audit_enabled == AUDIT_OFF)
882                 return;
883 
884         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
885         audit_log_task_info(ab, current);
886         audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
887                          audit_feature_names[which], !!old_feature, !!new_feature,
888                          !!old_lock, !!new_lock, res);
889         audit_log_end(ab);
890 }
891 
892 static int audit_set_feature(struct sk_buff *skb)
893 {
894         struct audit_features *uaf;
895         int i;
896 
897         BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
898         uaf = nlmsg_data(nlmsg_hdr(skb));
899 
900         /* if there is ever a version 2 we should handle that here */
901 
902         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
903                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
904                 u32 old_feature, new_feature, old_lock, new_lock;
905 
906                 /* if we are not changing this feature, move along */
907                 if (!(feature & uaf->mask))
908                         continue;
909 
910                 old_feature = af.features & feature;
911                 new_feature = uaf->features & feature;
912                 new_lock = (uaf->lock | af.lock) & feature;
913                 old_lock = af.lock & feature;
914 
915                 /* are we changing a locked feature? */
916                 if (old_lock && (new_feature != old_feature)) {
917                         audit_log_feature_change(i, old_feature, new_feature,
918                                                  old_lock, new_lock, 0);
919                         return -EPERM;
920                 }
921         }
922         /* nothing invalid, do the changes */
923         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
924                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
925                 u32 old_feature, new_feature, old_lock, new_lock;
926 
927                 /* if we are not changing this feature, move along */
928                 if (!(feature & uaf->mask))
929                         continue;
930 
931                 old_feature = af.features & feature;
932                 new_feature = uaf->features & feature;
933                 old_lock = af.lock & feature;
934                 new_lock = (uaf->lock | af.lock) & feature;
935 
936                 if (new_feature != old_feature)
937                         audit_log_feature_change(i, old_feature, new_feature,
938                                                  old_lock, new_lock, 1);
939 
940                 if (new_feature)
941                         af.features |= feature;
942                 else
943                         af.features &= ~feature;
944                 af.lock |= new_lock;
945         }
946 
947         return 0;
948 }
949 
950 static int audit_replace(pid_t pid)
951 {
952         struct sk_buff *skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0,
953                                                &pid, sizeof(pid));
954 
955         if (!skb)
956                 return -ENOMEM;
957         return netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
958 }
959 
960 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
961 {
962         u32                     seq;
963         void                    *data;
964         int                     err;
965         struct audit_buffer     *ab;
966         u16                     msg_type = nlh->nlmsg_type;
967         struct audit_sig_info   *sig_data;
968         char                    *ctx = NULL;
969         u32                     len;
970 
971         err = audit_netlink_ok(skb, msg_type);
972         if (err)
973                 return err;
974 
975         seq  = nlh->nlmsg_seq;
976         data = nlmsg_data(nlh);
977 
978         switch (msg_type) {
979         case AUDIT_GET: {
980                 struct audit_status     s;
981                 memset(&s, 0, sizeof(s));
982                 s.enabled               = audit_enabled;
983                 s.failure               = audit_failure;
984                 s.pid                   = audit_pid;
985                 s.rate_limit            = audit_rate_limit;
986                 s.backlog_limit         = audit_backlog_limit;
987                 s.lost                  = atomic_read(&audit_lost);
988                 s.backlog               = skb_queue_len(&audit_queue);
989                 s.feature_bitmap        = AUDIT_FEATURE_BITMAP_ALL;
990                 s.backlog_wait_time     = audit_backlog_wait_time;
991                 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
992                 break;
993         }
994         case AUDIT_SET: {
995                 struct audit_status     s;
996                 memset(&s, 0, sizeof(s));
997                 /* guard against past and future API changes */
998                 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
999                 if (s.mask & AUDIT_STATUS_ENABLED) {
1000                         err = audit_set_enabled(s.enabled);
1001                         if (err < 0)
1002                                 return err;
1003                 }
1004                 if (s.mask & AUDIT_STATUS_FAILURE) {
1005                         err = audit_set_failure(s.failure);
1006                         if (err < 0)
1007                                 return err;
1008                 }
1009                 if (s.mask & AUDIT_STATUS_PID) {
1010                         /* NOTE: we are using task_tgid_vnr() below because
1011                          *       the s.pid value is relative to the namespace
1012                          *       of the caller; at present this doesn't matter
1013                          *       much since you can really only run auditd
1014                          *       from the initial pid namespace, but something
1015                          *       to keep in mind if this changes */
1016                         int new_pid = s.pid;
1017                         pid_t requesting_pid = task_tgid_vnr(current);
1018 
1019                         if ((!new_pid) && (requesting_pid != audit_pid)) {
1020                                 audit_log_config_change("audit_pid", new_pid, audit_pid, 0);
1021                                 return -EACCES;
1022                         }
1023                         if (audit_pid && new_pid &&
1024                             audit_replace(requesting_pid) != -ECONNREFUSED) {
1025                                 audit_log_config_change("audit_pid", new_pid, audit_pid, 0);
1026                                 return -EEXIST;
1027                         }
1028                         if (audit_enabled != AUDIT_OFF)
1029                                 audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
1030                         if (new_pid) {
1031                                 if (audit_sock)
1032                                         sock_put(audit_sock);
1033                                 audit_pid = new_pid;
1034                                 audit_nlk_portid = NETLINK_CB(skb).portid;
1035                                 sock_hold(skb->sk);
1036                                 audit_sock = skb->sk;
1037                         } else {
1038                                 auditd_reset();
1039                         }
1040                         wake_up_interruptible(&kauditd_wait);
1041                 }
1042                 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1043                         err = audit_set_rate_limit(s.rate_limit);
1044                         if (err < 0)
1045                                 return err;
1046                 }
1047                 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1048                         err = audit_set_backlog_limit(s.backlog_limit);
1049                         if (err < 0)
1050                                 return err;
1051                 }
1052                 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1053                         if (sizeof(s) > (size_t)nlh->nlmsg_len)
1054                                 return -EINVAL;
1055                         if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1056                                 return -EINVAL;
1057                         err = audit_set_backlog_wait_time(s.backlog_wait_time);
1058                         if (err < 0)
1059                                 return err;
1060                 }
1061                 break;
1062         }
1063         case AUDIT_GET_FEATURE:
1064                 err = audit_get_feature(skb);
1065                 if (err)
1066                         return err;
1067                 break;
1068         case AUDIT_SET_FEATURE:
1069                 err = audit_set_feature(skb);
1070                 if (err)
1071                         return err;
1072                 break;
1073         case AUDIT_USER:
1074         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1075         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1076                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1077                         return 0;
1078 
1079                 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1080                 if (err == 1) { /* match or error */
1081                         err = 0;
1082                         if (msg_type == AUDIT_USER_TTY) {
1083                                 err = tty_audit_push();
1084                                 if (err)
1085                                         break;
1086                         }
1087                         mutex_unlock(&audit_cmd_mutex);
1088                         audit_log_common_recv_msg(&ab, msg_type);
1089                         if (msg_type != AUDIT_USER_TTY)
1090                                 audit_log_format(ab, " msg='%.*s'",
1091                                                  AUDIT_MESSAGE_TEXT_MAX,
1092                                                  (char *)data);
1093                         else {
1094                                 int size;
1095 
1096                                 audit_log_format(ab, " data=");
1097                                 size = nlmsg_len(nlh);
1098                                 if (size > 0 &&
1099                                     ((unsigned char *)data)[size - 1] == '\0')
1100                                         size--;
1101                                 audit_log_n_untrustedstring(ab, data, size);
1102                         }
1103                         audit_set_portid(ab, NETLINK_CB(skb).portid);
1104                         audit_log_end(ab);
1105                         mutex_lock(&audit_cmd_mutex);
1106                 }
1107                 break;
1108         case AUDIT_ADD_RULE:
1109         case AUDIT_DEL_RULE:
1110                 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
1111                         return -EINVAL;
1112                 if (audit_enabled == AUDIT_LOCKED) {
1113                         audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1114                         audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
1115                         audit_log_end(ab);
1116                         return -EPERM;
1117                 }
1118                 err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
1119                                            seq, data, nlmsg_len(nlh));
1120                 break;
1121         case AUDIT_LIST_RULES:
1122                 err = audit_list_rules_send(skb, seq);
1123                 break;
1124         case AUDIT_TRIM:
1125                 audit_trim_trees();
1126                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1127                 audit_log_format(ab, " op=trim res=1");
1128                 audit_log_end(ab);
1129                 break;
1130         case AUDIT_MAKE_EQUIV: {
1131                 void *bufp = data;
1132                 u32 sizes[2];
1133                 size_t msglen = nlmsg_len(nlh);
1134                 char *old, *new;
1135 
1136                 err = -EINVAL;
1137                 if (msglen < 2 * sizeof(u32))
1138                         break;
1139                 memcpy(sizes, bufp, 2 * sizeof(u32));
1140                 bufp += 2 * sizeof(u32);
1141                 msglen -= 2 * sizeof(u32);
1142                 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1143                 if (IS_ERR(old)) {
1144                         err = PTR_ERR(old);
1145                         break;
1146                 }
1147                 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1148                 if (IS_ERR(new)) {
1149                         err = PTR_ERR(new);
1150                         kfree(old);
1151                         break;
1152                 }
1153                 /* OK, here comes... */
1154                 err = audit_tag_tree(old, new);
1155 
1156                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1157 
1158                 audit_log_format(ab, " op=make_equiv old=");
1159                 audit_log_untrustedstring(ab, old);
1160                 audit_log_format(ab, " new=");
1161                 audit_log_untrustedstring(ab, new);
1162                 audit_log_format(ab, " res=%d", !err);
1163                 audit_log_end(ab);
1164                 kfree(old);
1165                 kfree(new);
1166                 break;
1167         }
1168         case AUDIT_SIGNAL_INFO:
1169                 len = 0;
1170                 if (audit_sig_sid) {
1171                         err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1172                         if (err)
1173                                 return err;
1174                 }
1175                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1176                 if (!sig_data) {
1177                         if (audit_sig_sid)
1178                                 security_release_secctx(ctx, len);
1179                         return -ENOMEM;
1180                 }
1181                 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1182                 sig_data->pid = audit_sig_pid;
1183                 if (audit_sig_sid) {
1184                         memcpy(sig_data->ctx, ctx, len);
1185                         security_release_secctx(ctx, len);
1186                 }
1187                 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1188                                  sig_data, sizeof(*sig_data) + len);
1189                 kfree(sig_data);
1190                 break;
1191         case AUDIT_TTY_GET: {
1192                 struct audit_tty_status s;
1193                 unsigned int t;
1194 
1195                 t = READ_ONCE(current->signal->audit_tty);
1196                 s.enabled = t & AUDIT_TTY_ENABLE;
1197                 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1198 
1199                 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1200                 break;
1201         }
1202         case AUDIT_TTY_SET: {
1203                 struct audit_tty_status s, old;
1204                 struct audit_buffer     *ab;
1205                 unsigned int t;
1206 
1207                 memset(&s, 0, sizeof(s));
1208                 /* guard against past and future API changes */
1209                 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1210                 /* check if new data is valid */
1211                 if ((s.enabled != 0 && s.enabled != 1) ||
1212                     (s.log_passwd != 0 && s.log_passwd != 1))
1213                         err = -EINVAL;
1214 
1215                 if (err)
1216                         t = READ_ONCE(current->signal->audit_tty);
1217                 else {
1218                         t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1219                         t = xchg(&current->signal->audit_tty, t);
1220                 }
1221                 old.enabled = t & AUDIT_TTY_ENABLE;
1222                 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1223 
1224                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1225                 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1226                                  " old-log_passwd=%d new-log_passwd=%d res=%d",
1227                                  old.enabled, s.enabled, old.log_passwd,
1228                                  s.log_passwd, !err);
1229                 audit_log_end(ab);
1230                 break;
1231         }
1232         default:
1233                 err = -EINVAL;
1234                 break;
1235         }
1236 
1237         return err < 0 ? err : 0;
1238 }
1239 
1240 /*
1241  * Get message from skb.  Each message is processed by audit_receive_msg.
1242  * Malformed skbs with wrong length are discarded silently.
1243  */
1244 static void audit_receive_skb(struct sk_buff *skb)
1245 {
1246         struct nlmsghdr *nlh;
1247         /*
1248          * len MUST be signed for nlmsg_next to be able to dec it below 0
1249          * if the nlmsg_len was not aligned
1250          */
1251         int len;
1252         int err;
1253 
1254         nlh = nlmsg_hdr(skb);
1255         len = skb->len;
1256 
1257         while (nlmsg_ok(nlh, len)) {
1258                 err = audit_receive_msg(skb, nlh);
1259                 /* if err or if this message says it wants a response */
1260                 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1261                         netlink_ack(skb, nlh, err);
1262 
1263                 nlh = nlmsg_next(nlh, &len);
1264         }
1265 }
1266 
1267 /* Receive messages from netlink socket. */
1268 static void audit_receive(struct sk_buff  *skb)
1269 {
1270         mutex_lock(&audit_cmd_mutex);
1271         audit_receive_skb(skb);
1272         mutex_unlock(&audit_cmd_mutex);
1273 }
1274 
1275 /* Run custom bind function on netlink socket group connect or bind requests. */
1276 static int audit_bind(struct net *net, int group)
1277 {
1278         if (!capable(CAP_AUDIT_READ))
1279                 return -EPERM;
1280 
1281         return 0;
1282 }
1283 
1284 static int __net_init audit_net_init(struct net *net)
1285 {
1286         struct netlink_kernel_cfg cfg = {
1287                 .input  = audit_receive,
1288                 .bind   = audit_bind,
1289                 .flags  = NL_CFG_F_NONROOT_RECV,
1290                 .groups = AUDIT_NLGRP_MAX,
1291         };
1292 
1293         struct audit_net *aunet = net_generic(net, audit_net_id);
1294 
1295         aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1296         if (aunet->nlsk == NULL) {
1297                 audit_panic("cannot initialize netlink socket in namespace");
1298                 return -ENOMEM;
1299         }
1300         aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1301         return 0;
1302 }
1303 
1304 static void __net_exit audit_net_exit(struct net *net)
1305 {
1306         struct audit_net *aunet = net_generic(net, audit_net_id);
1307         struct sock *sock = aunet->nlsk;
1308         mutex_lock(&audit_cmd_mutex);
1309         if (sock == audit_sock)
1310                 auditd_reset();
1311         mutex_unlock(&audit_cmd_mutex);
1312 
1313         netlink_kernel_release(sock);
1314         aunet->nlsk = NULL;
1315 }
1316 
1317 static struct pernet_operations audit_net_ops __net_initdata = {
1318         .init = audit_net_init,
1319         .exit = audit_net_exit,
1320         .id = &audit_net_id,
1321         .size = sizeof(struct audit_net),
1322 };
1323 
1324 /* Initialize audit support at boot time. */
1325 static int __init audit_init(void)
1326 {
1327         int i;
1328 
1329         if (audit_initialized == AUDIT_DISABLED)
1330                 return 0;
1331 
1332         pr_info("initializing netlink subsys (%s)\n",
1333                 audit_default ? "enabled" : "disabled");
1334         register_pernet_subsys(&audit_net_ops);
1335 
1336         skb_queue_head_init(&audit_queue);
1337         skb_queue_head_init(&audit_retry_queue);
1338         skb_queue_head_init(&audit_hold_queue);
1339         audit_initialized = AUDIT_INITIALIZED;
1340         audit_enabled = audit_default;
1341         audit_ever_enabled |= !!audit_default;
1342 
1343         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1344                 INIT_LIST_HEAD(&audit_inode_hash[i]);
1345 
1346         kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1347         if (IS_ERR(kauditd_task)) {
1348                 int err = PTR_ERR(kauditd_task);
1349                 panic("audit: failed to start the kauditd thread (%d)\n", err);
1350         }
1351 
1352         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
1353 
1354         return 0;
1355 }
1356 __initcall(audit_init);
1357 
1358 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
1359 static int __init audit_enable(char *str)
1360 {
1361         audit_default = !!simple_strtol(str, NULL, 0);
1362         if (!audit_default)
1363                 audit_initialized = AUDIT_DISABLED;
1364 
1365         pr_info("%s\n", audit_default ?
1366                 "enabled (after initialization)" : "disabled (until reboot)");
1367 
1368         return 1;
1369 }
1370 __setup("audit=", audit_enable);
1371 
1372 /* Process kernel command-line parameter at boot time.
1373  * audit_backlog_limit=<n> */
1374 static int __init audit_backlog_limit_set(char *str)
1375 {
1376         u32 audit_backlog_limit_arg;
1377 
1378         pr_info("audit_backlog_limit: ");
1379         if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1380                 pr_cont("using default of %u, unable to parse %s\n",
1381                         audit_backlog_limit, str);
1382                 return 1;
1383         }
1384 
1385         audit_backlog_limit = audit_backlog_limit_arg;
1386         pr_cont("%d\n", audit_backlog_limit);
1387 
1388         return 1;
1389 }
1390 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1391 
1392 static void audit_buffer_free(struct audit_buffer *ab)
1393 {
1394         unsigned long flags;
1395 
1396         if (!ab)
1397                 return;
1398 
1399         kfree_skb(ab->skb);
1400         spin_lock_irqsave(&audit_freelist_lock, flags);
1401         if (audit_freelist_count > AUDIT_MAXFREE)
1402                 kfree(ab);
1403         else {
1404                 audit_freelist_count++;
1405                 list_add(&ab->list, &audit_freelist);
1406         }
1407         spin_unlock_irqrestore(&audit_freelist_lock, flags);
1408 }
1409 
1410 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1411                                                 gfp_t gfp_mask, int type)
1412 {
1413         unsigned long flags;
1414         struct audit_buffer *ab = NULL;
1415         struct nlmsghdr *nlh;
1416 
1417         spin_lock_irqsave(&audit_freelist_lock, flags);
1418         if (!list_empty(&audit_freelist)) {
1419                 ab = list_entry(audit_freelist.next,
1420                                 struct audit_buffer, list);
1421                 list_del(&ab->list);
1422                 --audit_freelist_count;
1423         }
1424         spin_unlock_irqrestore(&audit_freelist_lock, flags);
1425 
1426         if (!ab) {
1427                 ab = kmalloc(sizeof(*ab), gfp_mask);
1428                 if (!ab)
1429                         goto err;
1430         }
1431 
1432         ab->ctx = ctx;
1433         ab->gfp_mask = gfp_mask;
1434 
1435         ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1436         if (!ab->skb)
1437                 goto err;
1438 
1439         nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1440         if (!nlh)
1441                 goto out_kfree_skb;
1442 
1443         return ab;
1444 
1445 out_kfree_skb:
1446         kfree_skb(ab->skb);
1447         ab->skb = NULL;
1448 err:
1449         audit_buffer_free(ab);
1450         return NULL;
1451 }
1452 
1453 /**
1454  * audit_serial - compute a serial number for the audit record
1455  *
1456  * Compute a serial number for the audit record.  Audit records are
1457  * written to user-space as soon as they are generated, so a complete
1458  * audit record may be written in several pieces.  The timestamp of the
1459  * record and this serial number are used by the user-space tools to
1460  * determine which pieces belong to the same audit record.  The
1461  * (timestamp,serial) tuple is unique for each syscall and is live from
1462  * syscall entry to syscall exit.
1463  *
1464  * NOTE: Another possibility is to store the formatted records off the
1465  * audit context (for those records that have a context), and emit them
1466  * all at syscall exit.  However, this could delay the reporting of
1467  * significant errors until syscall exit (or never, if the system
1468  * halts).
1469  */
1470 unsigned int audit_serial(void)
1471 {
1472         static atomic_t serial = ATOMIC_INIT(0);
1473 
1474         return atomic_add_return(1, &serial);
1475 }
1476 
1477 static inline void audit_get_stamp(struct audit_context *ctx,
1478                                    struct timespec *t, unsigned int *serial)
1479 {
1480         if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1481                 *t = CURRENT_TIME;
1482                 *serial = audit_serial();
1483         }
1484 }
1485 
1486 /**
1487  * audit_log_start - obtain an audit buffer
1488  * @ctx: audit_context (may be NULL)
1489  * @gfp_mask: type of allocation
1490  * @type: audit message type
1491  *
1492  * Returns audit_buffer pointer on success or NULL on error.
1493  *
1494  * Obtain an audit buffer.  This routine does locking to obtain the
1495  * audit buffer, but then no locking is required for calls to
1496  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1497  * syscall, then the syscall is marked as auditable and an audit record
1498  * will be written at syscall exit.  If there is no associated task, then
1499  * task context (ctx) should be NULL.
1500  */
1501 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1502                                      int type)
1503 {
1504         struct audit_buffer *ab;
1505         struct timespec t;
1506         unsigned int uninitialized_var(serial);
1507 
1508         if (audit_initialized != AUDIT_INITIALIZED)
1509                 return NULL;
1510 
1511         if (unlikely(!audit_filter(type, AUDIT_FILTER_TYPE)))
1512                 return NULL;
1513 
1514         /* don't ever fail/sleep on these two conditions:
1515          * 1. auditd generated record - since we need auditd to drain the
1516          *    queue; also, when we are checking for auditd, compare PIDs using
1517          *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1518          *    using a PID anchored in the caller's namespace
1519          * 2. audit command message - record types 1000 through 1099 inclusive
1520          *    are command messages/records used to manage the kernel subsystem
1521          *    and the audit userspace, blocking on these messages could cause
1522          *    problems under load so don't do it (note: not all of these
1523          *    command types are valid as record types, but it is quicker to
1524          *    just check two ints than a series of ints in a if/switch stmt) */
1525         if (!((audit_pid && audit_pid == task_tgid_vnr(current)) ||
1526               (type >= 1000 && type <= 1099))) {
1527                 long sleep_time = audit_backlog_wait_time;
1528 
1529                 while (audit_backlog_limit &&
1530                        (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1531                         /* wake kauditd to try and flush the queue */
1532                         wake_up_interruptible(&kauditd_wait);
1533 
1534                         /* sleep if we are allowed and we haven't exhausted our
1535                          * backlog wait limit */
1536                         if ((gfp_mask & __GFP_DIRECT_RECLAIM) &&
1537                             (sleep_time > 0)) {
1538                                 DECLARE_WAITQUEUE(wait, current);
1539 
1540                                 add_wait_queue_exclusive(&audit_backlog_wait,
1541                                                          &wait);
1542                                 set_current_state(TASK_UNINTERRUPTIBLE);
1543                                 sleep_time = schedule_timeout(sleep_time);
1544                                 remove_wait_queue(&audit_backlog_wait, &wait);
1545                         } else {
1546                                 if (audit_rate_check() && printk_ratelimit())
1547                                         pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1548                                                 skb_queue_len(&audit_queue),
1549                                                 audit_backlog_limit);
1550                                 audit_log_lost("backlog limit exceeded");
1551                                 return NULL;
1552                         }
1553                 }
1554         }
1555 
1556         ab = audit_buffer_alloc(ctx, gfp_mask, type);
1557         if (!ab) {
1558                 audit_log_lost("out of memory in audit_log_start");
1559                 return NULL;
1560         }
1561 
1562         audit_get_stamp(ab->ctx, &t, &serial);
1563         audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1564                          t.tv_sec, t.tv_nsec/1000000, serial);
1565 
1566         return ab;
1567 }
1568 
1569 /**
1570  * audit_expand - expand skb in the audit buffer
1571  * @ab: audit_buffer
1572  * @extra: space to add at tail of the skb
1573  *
1574  * Returns 0 (no space) on failed expansion, or available space if
1575  * successful.
1576  */
1577 static inline int audit_expand(struct audit_buffer *ab, int extra)
1578 {
1579         struct sk_buff *skb = ab->skb;
1580         int oldtail = skb_tailroom(skb);
1581         int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1582         int newtail = skb_tailroom(skb);
1583 
1584         if (ret < 0) {
1585                 audit_log_lost("out of memory in audit_expand");
1586                 return 0;
1587         }
1588 
1589         skb->truesize += newtail - oldtail;
1590         return newtail;
1591 }
1592 
1593 /*
1594  * Format an audit message into the audit buffer.  If there isn't enough
1595  * room in the audit buffer, more room will be allocated and vsnprint
1596  * will be called a second time.  Currently, we assume that a printk
1597  * can't format message larger than 1024 bytes, so we don't either.
1598  */
1599 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1600                               va_list args)
1601 {
1602         int len, avail;
1603         struct sk_buff *skb;
1604         va_list args2;
1605 
1606         if (!ab)
1607                 return;
1608 
1609         BUG_ON(!ab->skb);
1610         skb = ab->skb;
1611         avail = skb_tailroom(skb);
1612         if (avail == 0) {
1613                 avail = audit_expand(ab, AUDIT_BUFSIZ);
1614                 if (!avail)
1615                         goto out;
1616         }
1617         va_copy(args2, args);
1618         len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1619         if (len >= avail) {
1620                 /* The printk buffer is 1024 bytes long, so if we get
1621                  * here and AUDIT_BUFSIZ is at least 1024, then we can
1622                  * log everything that printk could have logged. */
1623                 avail = audit_expand(ab,
1624                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1625                 if (!avail)
1626                         goto out_va_end;
1627                 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1628         }
1629         if (len > 0)
1630                 skb_put(skb, len);
1631 out_va_end:
1632         va_end(args2);
1633 out:
1634         return;
1635 }
1636 
1637 /**
1638  * audit_log_format - format a message into the audit buffer.
1639  * @ab: audit_buffer
1640  * @fmt: format string
1641  * @...: optional parameters matching @fmt string
1642  *
1643  * All the work is done in audit_log_vformat.
1644  */
1645 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1646 {
1647         va_list args;
1648 
1649         if (!ab)
1650                 return;
1651         va_start(args, fmt);
1652         audit_log_vformat(ab, fmt, args);
1653         va_end(args);
1654 }
1655 
1656 /**
1657  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1658  * @ab: the audit_buffer
1659  * @buf: buffer to convert to hex
1660  * @len: length of @buf to be converted
1661  *
1662  * No return value; failure to expand is silently ignored.
1663  *
1664  * This function will take the passed buf and convert it into a string of
1665  * ascii hex digits. The new string is placed onto the skb.
1666  */
1667 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1668                 size_t len)
1669 {
1670         int i, avail, new_len;
1671         unsigned char *ptr;
1672         struct sk_buff *skb;
1673 
1674         if (!ab)
1675                 return;
1676 
1677         BUG_ON(!ab->skb);
1678         skb = ab->skb;
1679         avail = skb_tailroom(skb);
1680         new_len = len<<1;
1681         if (new_len >= avail) {
1682                 /* Round the buffer request up to the next multiple */
1683                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1684                 avail = audit_expand(ab, new_len);
1685                 if (!avail)
1686                         return;
1687         }
1688 
1689         ptr = skb_tail_pointer(skb);
1690         for (i = 0; i < len; i++)
1691                 ptr = hex_byte_pack_upper(ptr, buf[i]);
1692         *ptr = 0;
1693         skb_put(skb, len << 1); /* new string is twice the old string */
1694 }
1695 
1696 /*
1697  * Format a string of no more than slen characters into the audit buffer,
1698  * enclosed in quote marks.
1699  */
1700 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1701                         size_t slen)
1702 {
1703         int avail, new_len;
1704         unsigned char *ptr;
1705         struct sk_buff *skb;
1706 
1707         if (!ab)
1708                 return;
1709 
1710         BUG_ON(!ab->skb);
1711         skb = ab->skb;
1712         avail = skb_tailroom(skb);
1713         new_len = slen + 3;     /* enclosing quotes + null terminator */
1714         if (new_len > avail) {
1715                 avail = audit_expand(ab, new_len);
1716                 if (!avail)
1717                         return;
1718         }
1719         ptr = skb_tail_pointer(skb);
1720         *ptr++ = '"';
1721         memcpy(ptr, string, slen);
1722         ptr += slen;
1723         *ptr++ = '"';
1724         *ptr = 0;
1725         skb_put(skb, slen + 2); /* don't include null terminator */
1726 }
1727 
1728 /**
1729  * audit_string_contains_control - does a string need to be logged in hex
1730  * @string: string to be checked
1731  * @len: max length of the string to check
1732  */
1733 bool audit_string_contains_control(const char *string, size_t len)
1734 {
1735         const unsigned char *p;
1736         for (p = string; p < (const unsigned char *)string + len; p++) {
1737                 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1738                         return true;
1739         }
1740         return false;
1741 }
1742 
1743 /**
1744  * audit_log_n_untrustedstring - log a string that may contain random characters
1745  * @ab: audit_buffer
1746  * @len: length of string (not including trailing null)
1747  * @string: string to be logged
1748  *
1749  * This code will escape a string that is passed to it if the string
1750  * contains a control character, unprintable character, double quote mark,
1751  * or a space. Unescaped strings will start and end with a double quote mark.
1752  * Strings that are escaped are printed in hex (2 digits per char).
1753  *
1754  * The caller specifies the number of characters in the string to log, which may
1755  * or may not be the entire string.
1756  */
1757 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1758                                  size_t len)
1759 {
1760         if (audit_string_contains_control(string, len))
1761                 audit_log_n_hex(ab, string, len);
1762         else
1763                 audit_log_n_string(ab, string, len);
1764 }
1765 
1766 /**
1767  * audit_log_untrustedstring - log a string that may contain random characters
1768  * @ab: audit_buffer
1769  * @string: string to be logged
1770  *
1771  * Same as audit_log_n_untrustedstring(), except that strlen is used to
1772  * determine string length.
1773  */
1774 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1775 {
1776         audit_log_n_untrustedstring(ab, string, strlen(string));
1777 }
1778 
1779 /* This is a helper-function to print the escaped d_path */
1780 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1781                       const struct path *path)
1782 {
1783         char *p, *pathname;
1784 
1785         if (prefix)
1786                 audit_log_format(ab, "%s", prefix);
1787 
1788         /* We will allow 11 spaces for ' (deleted)' to be appended */
1789         pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1790         if (!pathname) {
1791                 audit_log_string(ab, "<no_memory>");
1792                 return;
1793         }
1794         p = d_path(path, pathname, PATH_MAX+11);
1795         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1796                 /* FIXME: can we save some information here? */
1797                 audit_log_string(ab, "<too_long>");
1798         } else
1799                 audit_log_untrustedstring(ab, p);
1800         kfree(pathname);
1801 }
1802 
1803 void audit_log_session_info(struct audit_buffer *ab)
1804 {
1805         unsigned int sessionid = audit_get_sessionid(current);
1806         uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1807 
1808         audit_log_format(ab, " auid=%u ses=%u", auid, sessionid);
1809 }
1810 
1811 void audit_log_key(struct audit_buffer *ab, char *key)
1812 {
1813         audit_log_format(ab, " key=");
1814         if (key)
1815                 audit_log_untrustedstring(ab, key);
1816         else
1817                 audit_log_format(ab, "(null)");
1818 }
1819 
1820 void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1821 {
1822         int i;
1823 
1824         audit_log_format(ab, " %s=", prefix);
1825         CAP_FOR_EACH_U32(i) {
1826                 audit_log_format(ab, "%08x",
1827                                  cap->cap[CAP_LAST_U32 - i]);
1828         }
1829 }
1830 
1831 static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1832 {
1833         kernel_cap_t *perm = &name->fcap.permitted;
1834         kernel_cap_t *inh = &name->fcap.inheritable;
1835         int log = 0;
1836 
1837         if (!cap_isclear(*perm)) {
1838                 audit_log_cap(ab, "cap_fp", perm);
1839                 log = 1;
1840         }
1841         if (!cap_isclear(*inh)) {
1842                 audit_log_cap(ab, "cap_fi", inh);
1843                 log = 1;
1844         }
1845 
1846         if (log)
1847                 audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1848                                  name->fcap.fE, name->fcap_ver);
1849 }
1850 
1851 static inline int audit_copy_fcaps(struct audit_names *name,
1852                                    const struct dentry *dentry)
1853 {
1854         struct cpu_vfs_cap_data caps;
1855         int rc;
1856 
1857         if (!dentry)
1858                 return 0;
1859 
1860         rc = get_vfs_caps_from_disk(dentry, &caps);
1861         if (rc)
1862                 return rc;
1863 
1864         name->fcap.permitted = caps.permitted;
1865         name->fcap.inheritable = caps.inheritable;
1866         name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1867         name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1868                                 VFS_CAP_REVISION_SHIFT;
1869 
1870         return 0;
1871 }
1872 
1873 /* Copy inode data into an audit_names. */
1874 void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1875                       struct inode *inode)
1876 {
1877         name->ino   = inode->i_ino;
1878         name->dev   = inode->i_sb->s_dev;
1879         name->mode  = inode->i_mode;
1880         name->uid   = inode->i_uid;
1881         name->gid   = inode->i_gid;
1882         name->rdev  = inode->i_rdev;
1883         security_inode_getsecid(inode, &name->osid);
1884         audit_copy_fcaps(name, dentry);
1885 }
1886 
1887 /**
1888  * audit_log_name - produce AUDIT_PATH record from struct audit_names
1889  * @context: audit_context for the task
1890  * @n: audit_names structure with reportable details
1891  * @path: optional path to report instead of audit_names->name
1892  * @record_num: record number to report when handling a list of names
1893  * @call_panic: optional pointer to int that will be updated if secid fails
1894  */
1895 void audit_log_name(struct audit_context *context, struct audit_names *n,
1896                     const struct path *path, int record_num, int *call_panic)
1897 {
1898         struct audit_buffer *ab;
1899         ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1900         if (!ab)
1901                 return;
1902 
1903         audit_log_format(ab, "item=%d", record_num);
1904 
1905         if (path)
1906                 audit_log_d_path(ab, " name=", path);
1907         else if (n->name) {
1908                 switch (n->name_len) {
1909                 case AUDIT_NAME_FULL:
1910                         /* log the full path */
1911                         audit_log_format(ab, " name=");
1912                         audit_log_untrustedstring(ab, n->name->name);
1913                         break;
1914                 case 0:
1915                         /* name was specified as a relative path and the
1916                          * directory component is the cwd */
1917                         audit_log_d_path(ab, " name=", &context->pwd);
1918                         break;
1919                 default:
1920                         /* log the name's directory component */
1921                         audit_log_format(ab, " name=");
1922                         audit_log_n_untrustedstring(ab, n->name->name,
1923                                                     n->name_len);
1924                 }
1925         } else
1926                 audit_log_format(ab, " name=(null)");
1927 
1928         if (n->ino != AUDIT_INO_UNSET)
1929                 audit_log_format(ab, " inode=%lu"
1930                                  " dev=%02x:%02x mode=%#ho"
1931                                  " ouid=%u ogid=%u rdev=%02x:%02x",
1932                                  n->ino,
1933                                  MAJOR(n->dev),
1934                                  MINOR(n->dev),
1935                                  n->mode,
1936                                  from_kuid(&init_user_ns, n->uid),
1937                                  from_kgid(&init_user_ns, n->gid),
1938                                  MAJOR(n->rdev),
1939                                  MINOR(n->rdev));
1940         if (n->osid != 0) {
1941                 char *ctx = NULL;
1942                 u32 len;
1943                 if (security_secid_to_secctx(
1944                         n->osid, &ctx, &len)) {
1945                         audit_log_format(ab, " osid=%u", n->osid);
1946                         if (call_panic)
1947                                 *call_panic = 2;
1948                 } else {
1949                         audit_log_format(ab, " obj=%s", ctx);
1950                         security_release_secctx(ctx, len);
1951                 }
1952         }
1953 
1954         /* log the audit_names record type */
1955         audit_log_format(ab, " nametype=");
1956         switch(n->type) {
1957         case AUDIT_TYPE_NORMAL:
1958                 audit_log_format(ab, "NORMAL");
1959                 break;
1960         case AUDIT_TYPE_PARENT:
1961                 audit_log_format(ab, "PARENT");
1962                 break;
1963         case AUDIT_TYPE_CHILD_DELETE:
1964                 audit_log_format(ab, "DELETE");
1965                 break;
1966         case AUDIT_TYPE_CHILD_CREATE:
1967                 audit_log_format(ab, "CREATE");
1968                 break;
1969         default:
1970                 audit_log_format(ab, "UNKNOWN");
1971                 break;
1972         }
1973 
1974         audit_log_fcaps(ab, n);
1975         audit_log_end(ab);
1976 }
1977 
1978 int audit_log_task_context(struct audit_buffer *ab)
1979 {
1980         char *ctx = NULL;
1981         unsigned len;
1982         int error;
1983         u32 sid;
1984 
1985         security_task_getsecid(current, &sid);
1986         if (!sid)
1987                 return 0;
1988 
1989         error = security_secid_to_secctx(sid, &ctx, &len);
1990         if (error) {
1991                 if (error != -EINVAL)
1992                         goto error_path;
1993                 return 0;
1994         }
1995 
1996         audit_log_format(ab, " subj=%s", ctx);
1997         security_release_secctx(ctx, len);
1998         return 0;
1999 
2000 error_path:
2001         audit_panic("error in audit_log_task_context");
2002         return error;
2003 }
2004 EXPORT_SYMBOL(audit_log_task_context);
2005 
2006 void audit_log_d_path_exe(struct audit_buffer *ab,
2007                           struct mm_struct *mm)
2008 {
2009         struct file *exe_file;
2010 
2011         if (!mm)
2012                 goto out_null;
2013 
2014         exe_file = get_mm_exe_file(mm);
2015         if (!exe_file)
2016                 goto out_null;
2017 
2018         audit_log_d_path(ab, " exe=", &exe_file->f_path);
2019         fput(exe_file);
2020         return;
2021 out_null:
2022         audit_log_format(ab, " exe=(null)");
2023 }
2024 
2025 struct tty_struct *audit_get_tty(struct task_struct *tsk)
2026 {
2027         struct tty_struct *tty = NULL;
2028         unsigned long flags;
2029 
2030         spin_lock_irqsave(&tsk->sighand->siglock, flags);
2031         if (tsk->signal)
2032                 tty = tty_kref_get(tsk->signal->tty);
2033         spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
2034         return tty;
2035 }
2036 
2037 void audit_put_tty(struct tty_struct *tty)
2038 {
2039         tty_kref_put(tty);
2040 }
2041 
2042 void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
2043 {
2044         const struct cred *cred;
2045         char comm[sizeof(tsk->comm)];
2046         struct tty_struct *tty;
2047 
2048         if (!ab)
2049                 return;
2050 
2051         /* tsk == current */
2052         cred = current_cred();
2053         tty = audit_get_tty(tsk);
2054         audit_log_format(ab,
2055                          " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2056                          " euid=%u suid=%u fsuid=%u"
2057                          " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2058                          task_ppid_nr(tsk),
2059                          task_tgid_nr(tsk),
2060                          from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
2061                          from_kuid(&init_user_ns, cred->uid),
2062                          from_kgid(&init_user_ns, cred->gid),
2063                          from_kuid(&init_user_ns, cred->euid),
2064                          from_kuid(&init_user_ns, cred->suid),
2065                          from_kuid(&init_user_ns, cred->fsuid),
2066                          from_kgid(&init_user_ns, cred->egid),
2067                          from_kgid(&init_user_ns, cred->sgid),
2068                          from_kgid(&init_user_ns, cred->fsgid),
2069                          tty ? tty_name(tty) : "(none)",
2070                          audit_get_sessionid(tsk));
2071         audit_put_tty(tty);
2072         audit_log_format(ab, " comm=");
2073         audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
2074         audit_log_d_path_exe(ab, tsk->mm);
2075         audit_log_task_context(ab);
2076 }
2077 EXPORT_SYMBOL(audit_log_task_info);
2078 
2079 /**
2080  * audit_log_link_denied - report a link restriction denial
2081  * @operation: specific link operation
2082  * @link: the path that triggered the restriction
2083  */
2084 void audit_log_link_denied(const char *operation, const struct path *link)
2085 {
2086         struct audit_buffer *ab;
2087         struct audit_names *name;
2088 
2089         name = kzalloc(sizeof(*name), GFP_NOFS);
2090         if (!name)
2091                 return;
2092 
2093         /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
2094         ab = audit_log_start(current->audit_context, GFP_KERNEL,
2095                              AUDIT_ANOM_LINK);
2096         if (!ab)
2097                 goto out;
2098         audit_log_format(ab, "op=%s", operation);
2099         audit_log_task_info(ab, current);
2100         audit_log_format(ab, " res=0");
2101         audit_log_end(ab);
2102 
2103         /* Generate AUDIT_PATH record with object. */
2104         name->type = AUDIT_TYPE_NORMAL;
2105         audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
2106         audit_log_name(current->audit_context, name, link, 0, NULL);
2107 out:
2108         kfree(name);
2109 }
2110 
2111 /**
2112  * audit_log_end - end one audit record
2113  * @ab: the audit_buffer
2114  *
2115  * We can not do a netlink send inside an irq context because it blocks (last
2116  * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2117  * queue and a tasklet is scheduled to remove them from the queue outside the
2118  * irq context.  May be called in any context.
2119  */
2120 void audit_log_end(struct audit_buffer *ab)
2121 {
2122         if (!ab)
2123                 return;
2124         if (!audit_rate_check()) {
2125                 audit_log_lost("rate limit exceeded");
2126         } else {
2127                 skb_queue_tail(&audit_queue, ab->skb);
2128                 wake_up_interruptible(&kauditd_wait);
2129                 ab->skb = NULL;
2130         }
2131         audit_buffer_free(ab);
2132 }
2133 
2134 /**
2135  * audit_log - Log an audit record
2136  * @ctx: audit context
2137  * @gfp_mask: type of allocation
2138  * @type: audit message type
2139  * @fmt: format string to use
2140  * @...: variable parameters matching the format string
2141  *
2142  * This is a convenience function that calls audit_log_start,
2143  * audit_log_vformat, and audit_log_end.  It may be called
2144  * in any context.
2145  */
2146 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2147                const char *fmt, ...)
2148 {
2149         struct audit_buffer *ab;
2150         va_list args;
2151 
2152         ab = audit_log_start(ctx, gfp_mask, type);
2153         if (ab) {
2154                 va_start(args, fmt);
2155                 audit_log_vformat(ab, fmt, args);
2156                 va_end(args);
2157                 audit_log_end(ab);
2158         }
2159 }
2160 
2161 #ifdef CONFIG_SECURITY
2162 /**
2163  * audit_log_secctx - Converts and logs SELinux context
2164  * @ab: audit_buffer
2165  * @secid: security number
2166  *
2167  * This is a helper function that calls security_secid_to_secctx to convert
2168  * secid to secctx and then adds the (converted) SELinux context to the audit
2169  * log by calling audit_log_format, thus also preventing leak of internal secid
2170  * to userspace. If secid cannot be converted audit_panic is called.
2171  */
2172 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
2173 {
2174         u32 len;
2175         char *secctx;
2176 
2177         if (security_secid_to_secctx(secid, &secctx, &len)) {
2178                 audit_panic("Cannot convert secid to context");
2179         } else {
2180                 audit_log_format(ab, " obj=%s", secctx);
2181                 security_release_secctx(secctx, len);
2182         }
2183 }
2184 EXPORT_SYMBOL(audit_log_secctx);
2185 #endif
2186 
2187 EXPORT_SYMBOL(audit_log_start);
2188 EXPORT_SYMBOL(audit_log_end);
2189 EXPORT_SYMBOL(audit_log_format);
2190 EXPORT_SYMBOL(audit_log);
2191 

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