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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  * Audit userspace, documentation, tests, and bug/issue trackers:
 42  *      https://github.com/linux-audit
 43  */
 44 
 45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 46 
 47 #include <linux/file.h>
 48 #include <linux/init.h>
 49 #include <linux/types.h>
 50 #include <linux/atomic.h>
 51 #include <linux/mm.h>
 52 #include <linux/export.h>
 53 #include <linux/slab.h>
 54 #include <linux/err.h>
 55 #include <linux/kthread.h>
 56 #include <linux/kernel.h>
 57 #include <linux/syscalls.h>
 58 #include <linux/spinlock.h>
 59 #include <linux/rcupdate.h>
 60 #include <linux/mutex.h>
 61 #include <linux/gfp.h>
 62 #include <linux/pid.h>
 63 
 64 #include <linux/audit.h>
 65 
 66 #include <net/sock.h>
 67 #include <net/netlink.h>
 68 #include <linux/skbuff.h>
 69 #ifdef CONFIG_SECURITY
 70 #include <linux/security.h>
 71 #endif
 72 #include <linux/freezer.h>
 73 #include <linux/pid_namespace.h>
 74 #include <net/netns/generic.h>
 75 
 76 #include "audit.h"
 77 
 78 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
 79  * (Initialization happens after skb_init is called.) */
 80 #define AUDIT_DISABLED          -1
 81 #define AUDIT_UNINITIALIZED     0
 82 #define AUDIT_INITIALIZED       1
 83 static int      audit_initialized;
 84 
 85 u32             audit_enabled = AUDIT_OFF;
 86 bool            audit_ever_enabled = !!AUDIT_OFF;
 87 
 88 EXPORT_SYMBOL_GPL(audit_enabled);
 89 
 90 /* Default state when kernel boots without any parameters. */
 91 static u32      audit_default = AUDIT_OFF;
 92 
 93 /* If auditing cannot proceed, audit_failure selects what happens. */
 94 static u32      audit_failure = AUDIT_FAIL_PRINTK;
 95 
 96 /* private audit network namespace index */
 97 static unsigned int audit_net_id;
 98 
 99 /**
100  * struct audit_net - audit private network namespace data
101  * @sk: communication socket
102  */
103 struct audit_net {
104         struct sock *sk;
105 };
106 
107 /**
108  * struct auditd_connection - kernel/auditd connection state
109  * @pid: auditd PID
110  * @portid: netlink portid
111  * @net: the associated network namespace
112  * @rcu: RCU head
113  *
114  * Description:
115  * This struct is RCU protected; you must either hold the RCU lock for reading
116  * or the associated spinlock for writing.
117  */
118 static struct auditd_connection {
119         struct pid *pid;
120         u32 portid;
121         struct net *net;
122         struct rcu_head rcu;
123 } *auditd_conn = NULL;
124 static DEFINE_SPINLOCK(auditd_conn_lock);
125 
126 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
127  * to that number per second.  This prevents DoS attacks, but results in
128  * audit records being dropped. */
129 static u32      audit_rate_limit;
130 
131 /* Number of outstanding audit_buffers allowed.
132  * When set to zero, this means unlimited. */
133 static u32      audit_backlog_limit = 64;
134 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
135 static u32      audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
136 
137 /* The identity of the user shutting down the audit system. */
138 kuid_t          audit_sig_uid = INVALID_UID;
139 pid_t           audit_sig_pid = -1;
140 u32             audit_sig_sid = 0;
141 
142 /* Records can be lost in several ways:
143    0) [suppressed in audit_alloc]
144    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
145    2) out of memory in audit_log_move [alloc_skb]
146    3) suppressed due to audit_rate_limit
147    4) suppressed due to audit_backlog_limit
148 */
149 static atomic_t audit_lost = ATOMIC_INIT(0);
150 
151 /* Hash for inode-based rules */
152 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
153 
154 static struct kmem_cache *audit_buffer_cache;
155 
156 /* queue msgs to send via kauditd_task */
157 static struct sk_buff_head audit_queue;
158 /* queue msgs due to temporary unicast send problems */
159 static struct sk_buff_head audit_retry_queue;
160 /* queue msgs waiting for new auditd connection */
161 static struct sk_buff_head audit_hold_queue;
162 
163 /* queue servicing thread */
164 static struct task_struct *kauditd_task;
165 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
166 
167 /* waitqueue for callers who are blocked on the audit backlog */
168 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
169 
170 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
171                                    .mask = -1,
172                                    .features = 0,
173                                    .lock = 0,};
174 
175 static char *audit_feature_names[2] = {
176         "only_unset_loginuid",
177         "loginuid_immutable",
178 };
179 
180 /**
181  * struct audit_ctl_mutex - serialize requests from userspace
182  * @lock: the mutex used for locking
183  * @owner: the task which owns the lock
184  *
185  * Description:
186  * This is the lock struct used to ensure we only process userspace requests
187  * in an orderly fashion.  We can't simply use a mutex/lock here because we
188  * need to track lock ownership so we don't end up blocking the lock owner in
189  * audit_log_start() or similar.
190  */
191 static struct audit_ctl_mutex {
192         struct mutex lock;
193         void *owner;
194 } audit_cmd_mutex;
195 
196 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
197  * audit records.  Since printk uses a 1024 byte buffer, this buffer
198  * should be at least that large. */
199 #define AUDIT_BUFSIZ 1024
200 
201 /* The audit_buffer is used when formatting an audit record.  The caller
202  * locks briefly to get the record off the freelist or to allocate the
203  * buffer, and locks briefly to send the buffer to the netlink layer or
204  * to place it on a transmit queue.  Multiple audit_buffers can be in
205  * use simultaneously. */
206 struct audit_buffer {
207         struct sk_buff       *skb;      /* formatted skb ready to send */
208         struct audit_context *ctx;      /* NULL or associated context */
209         gfp_t                gfp_mask;
210 };
211 
212 struct audit_reply {
213         __u32 portid;
214         struct net *net;
215         struct sk_buff *skb;
216 };
217 
218 /**
219  * auditd_test_task - Check to see if a given task is an audit daemon
220  * @task: the task to check
221  *
222  * Description:
223  * Return 1 if the task is a registered audit daemon, 0 otherwise.
224  */
225 int auditd_test_task(struct task_struct *task)
226 {
227         int rc;
228         struct auditd_connection *ac;
229 
230         rcu_read_lock();
231         ac = rcu_dereference(auditd_conn);
232         rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
233         rcu_read_unlock();
234 
235         return rc;
236 }
237 
238 /**
239  * audit_ctl_lock - Take the audit control lock
240  */
241 void audit_ctl_lock(void)
242 {
243         mutex_lock(&audit_cmd_mutex.lock);
244         audit_cmd_mutex.owner = current;
245 }
246 
247 /**
248  * audit_ctl_unlock - Drop the audit control lock
249  */
250 void audit_ctl_unlock(void)
251 {
252         audit_cmd_mutex.owner = NULL;
253         mutex_unlock(&audit_cmd_mutex.lock);
254 }
255 
256 /**
257  * audit_ctl_owner_current - Test to see if the current task owns the lock
258  *
259  * Description:
260  * Return true if the current task owns the audit control lock, false if it
261  * doesn't own the lock.
262  */
263 static bool audit_ctl_owner_current(void)
264 {
265         return (current == audit_cmd_mutex.owner);
266 }
267 
268 /**
269  * auditd_pid_vnr - Return the auditd PID relative to the namespace
270  *
271  * Description:
272  * Returns the PID in relation to the namespace, 0 on failure.
273  */
274 static pid_t auditd_pid_vnr(void)
275 {
276         pid_t pid;
277         const struct auditd_connection *ac;
278 
279         rcu_read_lock();
280         ac = rcu_dereference(auditd_conn);
281         if (!ac || !ac->pid)
282                 pid = 0;
283         else
284                 pid = pid_vnr(ac->pid);
285         rcu_read_unlock();
286 
287         return pid;
288 }
289 
290 /**
291  * audit_get_sk - Return the audit socket for the given network namespace
292  * @net: the destination network namespace
293  *
294  * Description:
295  * Returns the sock pointer if valid, NULL otherwise.  The caller must ensure
296  * that a reference is held for the network namespace while the sock is in use.
297  */
298 static struct sock *audit_get_sk(const struct net *net)
299 {
300         struct audit_net *aunet;
301 
302         if (!net)
303                 return NULL;
304 
305         aunet = net_generic(net, audit_net_id);
306         return aunet->sk;
307 }
308 
309 void audit_panic(const char *message)
310 {
311         switch (audit_failure) {
312         case AUDIT_FAIL_SILENT:
313                 break;
314         case AUDIT_FAIL_PRINTK:
315                 if (printk_ratelimit())
316                         pr_err("%s\n", message);
317                 break;
318         case AUDIT_FAIL_PANIC:
319                 panic("audit: %s\n", message);
320                 break;
321         }
322 }
323 
324 static inline int audit_rate_check(void)
325 {
326         static unsigned long    last_check = 0;
327         static int              messages   = 0;
328         static DEFINE_SPINLOCK(lock);
329         unsigned long           flags;
330         unsigned long           now;
331         unsigned long           elapsed;
332         int                     retval     = 0;
333 
334         if (!audit_rate_limit) return 1;
335 
336         spin_lock_irqsave(&lock, flags);
337         if (++messages < audit_rate_limit) {
338                 retval = 1;
339         } else {
340                 now     = jiffies;
341                 elapsed = now - last_check;
342                 if (elapsed > HZ) {
343                         last_check = now;
344                         messages   = 0;
345                         retval     = 1;
346                 }
347         }
348         spin_unlock_irqrestore(&lock, flags);
349 
350         return retval;
351 }
352 
353 /**
354  * audit_log_lost - conditionally log lost audit message event
355  * @message: the message stating reason for lost audit message
356  *
357  * Emit at least 1 message per second, even if audit_rate_check is
358  * throttling.
359  * Always increment the lost messages counter.
360 */
361 void audit_log_lost(const char *message)
362 {
363         static unsigned long    last_msg = 0;
364         static DEFINE_SPINLOCK(lock);
365         unsigned long           flags;
366         unsigned long           now;
367         int                     print;
368 
369         atomic_inc(&audit_lost);
370 
371         print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
372 
373         if (!print) {
374                 spin_lock_irqsave(&lock, flags);
375                 now = jiffies;
376                 if (now - last_msg > HZ) {
377                         print = 1;
378                         last_msg = now;
379                 }
380                 spin_unlock_irqrestore(&lock, flags);
381         }
382 
383         if (print) {
384                 if (printk_ratelimit())
385                         pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
386                                 atomic_read(&audit_lost),
387                                 audit_rate_limit,
388                                 audit_backlog_limit);
389                 audit_panic(message);
390         }
391 }
392 
393 static int audit_log_config_change(char *function_name, u32 new, u32 old,
394                                    int allow_changes)
395 {
396         struct audit_buffer *ab;
397         int rc = 0;
398 
399         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
400         if (unlikely(!ab))
401                 return rc;
402         audit_log_format(ab, "%s=%u old=%u ", function_name, new, old);
403         audit_log_session_info(ab);
404         rc = audit_log_task_context(ab);
405         if (rc)
406                 allow_changes = 0; /* Something weird, deny request */
407         audit_log_format(ab, " res=%d", allow_changes);
408         audit_log_end(ab);
409         return rc;
410 }
411 
412 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
413 {
414         int allow_changes, rc = 0;
415         u32 old = *to_change;
416 
417         /* check if we are locked */
418         if (audit_enabled == AUDIT_LOCKED)
419                 allow_changes = 0;
420         else
421                 allow_changes = 1;
422 
423         if (audit_enabled != AUDIT_OFF) {
424                 rc = audit_log_config_change(function_name, new, old, allow_changes);
425                 if (rc)
426                         allow_changes = 0;
427         }
428 
429         /* If we are allowed, make the change */
430         if (allow_changes == 1)
431                 *to_change = new;
432         /* Not allowed, update reason */
433         else if (rc == 0)
434                 rc = -EPERM;
435         return rc;
436 }
437 
438 static int audit_set_rate_limit(u32 limit)
439 {
440         return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
441 }
442 
443 static int audit_set_backlog_limit(u32 limit)
444 {
445         return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
446 }
447 
448 static int audit_set_backlog_wait_time(u32 timeout)
449 {
450         return audit_do_config_change("audit_backlog_wait_time",
451                                       &audit_backlog_wait_time, timeout);
452 }
453 
454 static int audit_set_enabled(u32 state)
455 {
456         int rc;
457         if (state > AUDIT_LOCKED)
458                 return -EINVAL;
459 
460         rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
461         if (!rc)
462                 audit_ever_enabled |= !!state;
463 
464         return rc;
465 }
466 
467 static int audit_set_failure(u32 state)
468 {
469         if (state != AUDIT_FAIL_SILENT
470             && state != AUDIT_FAIL_PRINTK
471             && state != AUDIT_FAIL_PANIC)
472                 return -EINVAL;
473 
474         return audit_do_config_change("audit_failure", &audit_failure, state);
475 }
476 
477 /**
478  * auditd_conn_free - RCU helper to release an auditd connection struct
479  * @rcu: RCU head
480  *
481  * Description:
482  * Drop any references inside the auditd connection tracking struct and free
483  * the memory.
484  */
485 static void auditd_conn_free(struct rcu_head *rcu)
486 {
487         struct auditd_connection *ac;
488 
489         ac = container_of(rcu, struct auditd_connection, rcu);
490         put_pid(ac->pid);
491         put_net(ac->net);
492         kfree(ac);
493 }
494 
495 /**
496  * auditd_set - Set/Reset the auditd connection state
497  * @pid: auditd PID
498  * @portid: auditd netlink portid
499  * @net: auditd network namespace pointer
500  *
501  * Description:
502  * This function will obtain and drop network namespace references as
503  * necessary.  Returns zero on success, negative values on failure.
504  */
505 static int auditd_set(struct pid *pid, u32 portid, struct net *net)
506 {
507         unsigned long flags;
508         struct auditd_connection *ac_old, *ac_new;
509 
510         if (!pid || !net)
511                 return -EINVAL;
512 
513         ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
514         if (!ac_new)
515                 return -ENOMEM;
516         ac_new->pid = get_pid(pid);
517         ac_new->portid = portid;
518         ac_new->net = get_net(net);
519 
520         spin_lock_irqsave(&auditd_conn_lock, flags);
521         ac_old = rcu_dereference_protected(auditd_conn,
522                                            lockdep_is_held(&auditd_conn_lock));
523         rcu_assign_pointer(auditd_conn, ac_new);
524         spin_unlock_irqrestore(&auditd_conn_lock, flags);
525 
526         if (ac_old)
527                 call_rcu(&ac_old->rcu, auditd_conn_free);
528 
529         return 0;
530 }
531 
532 /**
533  * kauditd_print_skb - Print the audit record to the ring buffer
534  * @skb: audit record
535  *
536  * Whatever the reason, this packet may not make it to the auditd connection
537  * so write it via printk so the information isn't completely lost.
538  */
539 static void kauditd_printk_skb(struct sk_buff *skb)
540 {
541         struct nlmsghdr *nlh = nlmsg_hdr(skb);
542         char *data = nlmsg_data(nlh);
543 
544         if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
545                 pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
546 }
547 
548 /**
549  * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
550  * @skb: audit record
551  *
552  * Description:
553  * This should only be used by the kauditd_thread when it fails to flush the
554  * hold queue.
555  */
556 static void kauditd_rehold_skb(struct sk_buff *skb)
557 {
558         /* put the record back in the queue at the same place */
559         skb_queue_head(&audit_hold_queue, skb);
560 }
561 
562 /**
563  * kauditd_hold_skb - Queue an audit record, waiting for auditd
564  * @skb: audit record
565  *
566  * Description:
567  * Queue the audit record, waiting for an instance of auditd.  When this
568  * function is called we haven't given up yet on sending the record, but things
569  * are not looking good.  The first thing we want to do is try to write the
570  * record via printk and then see if we want to try and hold on to the record
571  * and queue it, if we have room.  If we want to hold on to the record, but we
572  * don't have room, record a record lost message.
573  */
574 static void kauditd_hold_skb(struct sk_buff *skb)
575 {
576         /* at this point it is uncertain if we will ever send this to auditd so
577          * try to send the message via printk before we go any further */
578         kauditd_printk_skb(skb);
579 
580         /* can we just silently drop the message? */
581         if (!audit_default) {
582                 kfree_skb(skb);
583                 return;
584         }
585 
586         /* if we have room, queue the message */
587         if (!audit_backlog_limit ||
588             skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
589                 skb_queue_tail(&audit_hold_queue, skb);
590                 return;
591         }
592 
593         /* we have no other options - drop the message */
594         audit_log_lost("kauditd hold queue overflow");
595         kfree_skb(skb);
596 }
597 
598 /**
599  * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
600  * @skb: audit record
601  *
602  * Description:
603  * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
604  * but for some reason we are having problems sending it audit records so
605  * queue the given record and attempt to resend.
606  */
607 static void kauditd_retry_skb(struct sk_buff *skb)
608 {
609         /* NOTE: because records should only live in the retry queue for a
610          * short period of time, before either being sent or moved to the hold
611          * queue, we don't currently enforce a limit on this queue */
612         skb_queue_tail(&audit_retry_queue, skb);
613 }
614 
615 /**
616  * auditd_reset - Disconnect the auditd connection
617  * @ac: auditd connection state
618  *
619  * Description:
620  * Break the auditd/kauditd connection and move all the queued records into the
621  * hold queue in case auditd reconnects.  It is important to note that the @ac
622  * pointer should never be dereferenced inside this function as it may be NULL
623  * or invalid, you can only compare the memory address!  If @ac is NULL then
624  * the connection will always be reset.
625  */
626 static void auditd_reset(const struct auditd_connection *ac)
627 {
628         unsigned long flags;
629         struct sk_buff *skb;
630         struct auditd_connection *ac_old;
631 
632         /* if it isn't already broken, break the connection */
633         spin_lock_irqsave(&auditd_conn_lock, flags);
634         ac_old = rcu_dereference_protected(auditd_conn,
635                                            lockdep_is_held(&auditd_conn_lock));
636         if (ac && ac != ac_old) {
637                 /* someone already registered a new auditd connection */
638                 spin_unlock_irqrestore(&auditd_conn_lock, flags);
639                 return;
640         }
641         rcu_assign_pointer(auditd_conn, NULL);
642         spin_unlock_irqrestore(&auditd_conn_lock, flags);
643 
644         if (ac_old)
645                 call_rcu(&ac_old->rcu, auditd_conn_free);
646 
647         /* flush the retry queue to the hold queue, but don't touch the main
648          * queue since we need to process that normally for multicast */
649         while ((skb = skb_dequeue(&audit_retry_queue)))
650                 kauditd_hold_skb(skb);
651 }
652 
653 /**
654  * auditd_send_unicast_skb - Send a record via unicast to auditd
655  * @skb: audit record
656  *
657  * Description:
658  * Send a skb to the audit daemon, returns positive/zero values on success and
659  * negative values on failure; in all cases the skb will be consumed by this
660  * function.  If the send results in -ECONNREFUSED the connection with auditd
661  * will be reset.  This function may sleep so callers should not hold any locks
662  * where this would cause a problem.
663  */
664 static int auditd_send_unicast_skb(struct sk_buff *skb)
665 {
666         int rc;
667         u32 portid;
668         struct net *net;
669         struct sock *sk;
670         struct auditd_connection *ac;
671 
672         /* NOTE: we can't call netlink_unicast while in the RCU section so
673          *       take a reference to the network namespace and grab local
674          *       copies of the namespace, the sock, and the portid; the
675          *       namespace and sock aren't going to go away while we hold a
676          *       reference and if the portid does become invalid after the RCU
677          *       section netlink_unicast() should safely return an error */
678 
679         rcu_read_lock();
680         ac = rcu_dereference(auditd_conn);
681         if (!ac) {
682                 rcu_read_unlock();
683                 kfree_skb(skb);
684                 rc = -ECONNREFUSED;
685                 goto err;
686         }
687         net = get_net(ac->net);
688         sk = audit_get_sk(net);
689         portid = ac->portid;
690         rcu_read_unlock();
691 
692         rc = netlink_unicast(sk, skb, portid, 0);
693         put_net(net);
694         if (rc < 0)
695                 goto err;
696 
697         return rc;
698 
699 err:
700         if (ac && rc == -ECONNREFUSED)
701                 auditd_reset(ac);
702         return rc;
703 }
704 
705 /**
706  * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
707  * @sk: the sending sock
708  * @portid: the netlink destination
709  * @queue: the skb queue to process
710  * @retry_limit: limit on number of netlink unicast failures
711  * @skb_hook: per-skb hook for additional processing
712  * @err_hook: hook called if the skb fails the netlink unicast send
713  *
714  * Description:
715  * Run through the given queue and attempt to send the audit records to auditd,
716  * returns zero on success, negative values on failure.  It is up to the caller
717  * to ensure that the @sk is valid for the duration of this function.
718  *
719  */
720 static int kauditd_send_queue(struct sock *sk, u32 portid,
721                               struct sk_buff_head *queue,
722                               unsigned int retry_limit,
723                               void (*skb_hook)(struct sk_buff *skb),
724                               void (*err_hook)(struct sk_buff *skb))
725 {
726         int rc = 0;
727         struct sk_buff *skb;
728         static unsigned int failed = 0;
729 
730         /* NOTE: kauditd_thread takes care of all our locking, we just use
731          *       the netlink info passed to us (e.g. sk and portid) */
732 
733         while ((skb = skb_dequeue(queue))) {
734                 /* call the skb_hook for each skb we touch */
735                 if (skb_hook)
736                         (*skb_hook)(skb);
737 
738                 /* can we send to anyone via unicast? */
739                 if (!sk) {
740                         if (err_hook)
741                                 (*err_hook)(skb);
742                         continue;
743                 }
744 
745                 /* grab an extra skb reference in case of error */
746                 skb_get(skb);
747                 rc = netlink_unicast(sk, skb, portid, 0);
748                 if (rc < 0) {
749                         /* fatal failure for our queue flush attempt? */
750                         if (++failed >= retry_limit ||
751                             rc == -ECONNREFUSED || rc == -EPERM) {
752                                 /* yes - error processing for the queue */
753                                 sk = NULL;
754                                 if (err_hook)
755                                         (*err_hook)(skb);
756                                 if (!skb_hook)
757                                         goto out;
758                                 /* keep processing with the skb_hook */
759                                 continue;
760                         } else
761                                 /* no - requeue to preserve ordering */
762                                 skb_queue_head(queue, skb);
763                 } else {
764                         /* it worked - drop the extra reference and continue */
765                         consume_skb(skb);
766                         failed = 0;
767                 }
768         }
769 
770 out:
771         return (rc >= 0 ? 0 : rc);
772 }
773 
774 /*
775  * kauditd_send_multicast_skb - Send a record to any multicast listeners
776  * @skb: audit record
777  *
778  * Description:
779  * Write a multicast message to anyone listening in the initial network
780  * namespace.  This function doesn't consume an skb as might be expected since
781  * it has to copy it anyways.
782  */
783 static void kauditd_send_multicast_skb(struct sk_buff *skb)
784 {
785         struct sk_buff *copy;
786         struct sock *sock = audit_get_sk(&init_net);
787         struct nlmsghdr *nlh;
788 
789         /* NOTE: we are not taking an additional reference for init_net since
790          *       we don't have to worry about it going away */
791 
792         if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
793                 return;
794 
795         /*
796          * The seemingly wasteful skb_copy() rather than bumping the refcount
797          * using skb_get() is necessary because non-standard mods are made to
798          * the skb by the original kaudit unicast socket send routine.  The
799          * existing auditd daemon assumes this breakage.  Fixing this would
800          * require co-ordinating a change in the established protocol between
801          * the kaudit kernel subsystem and the auditd userspace code.  There is
802          * no reason for new multicast clients to continue with this
803          * non-compliance.
804          */
805         copy = skb_copy(skb, GFP_KERNEL);
806         if (!copy)
807                 return;
808         nlh = nlmsg_hdr(copy);
809         nlh->nlmsg_len = skb->len;
810 
811         nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
812 }
813 
814 /**
815  * kauditd_thread - Worker thread to send audit records to userspace
816  * @dummy: unused
817  */
818 static int kauditd_thread(void *dummy)
819 {
820         int rc;
821         u32 portid = 0;
822         struct net *net = NULL;
823         struct sock *sk = NULL;
824         struct auditd_connection *ac;
825 
826 #define UNICAST_RETRIES 5
827 
828         set_freezable();
829         while (!kthread_should_stop()) {
830                 /* NOTE: see the lock comments in auditd_send_unicast_skb() */
831                 rcu_read_lock();
832                 ac = rcu_dereference(auditd_conn);
833                 if (!ac) {
834                         rcu_read_unlock();
835                         goto main_queue;
836                 }
837                 net = get_net(ac->net);
838                 sk = audit_get_sk(net);
839                 portid = ac->portid;
840                 rcu_read_unlock();
841 
842                 /* attempt to flush the hold queue */
843                 rc = kauditd_send_queue(sk, portid,
844                                         &audit_hold_queue, UNICAST_RETRIES,
845                                         NULL, kauditd_rehold_skb);
846                 if (ac && rc < 0) {
847                         sk = NULL;
848                         auditd_reset(ac);
849                         goto main_queue;
850                 }
851 
852                 /* attempt to flush the retry queue */
853                 rc = kauditd_send_queue(sk, portid,
854                                         &audit_retry_queue, UNICAST_RETRIES,
855                                         NULL, kauditd_hold_skb);
856                 if (ac && rc < 0) {
857                         sk = NULL;
858                         auditd_reset(ac);
859                         goto main_queue;
860                 }
861 
862 main_queue:
863                 /* process the main queue - do the multicast send and attempt
864                  * unicast, dump failed record sends to the retry queue; if
865                  * sk == NULL due to previous failures we will just do the
866                  * multicast send and move the record to the hold queue */
867                 rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
868                                         kauditd_send_multicast_skb,
869                                         (sk ?
870                                          kauditd_retry_skb : kauditd_hold_skb));
871                 if (ac && rc < 0)
872                         auditd_reset(ac);
873                 sk = NULL;
874 
875                 /* drop our netns reference, no auditd sends past this line */
876                 if (net) {
877                         put_net(net);
878                         net = NULL;
879                 }
880 
881                 /* we have processed all the queues so wake everyone */
882                 wake_up(&audit_backlog_wait);
883 
884                 /* NOTE: we want to wake up if there is anything on the queue,
885                  *       regardless of if an auditd is connected, as we need to
886                  *       do the multicast send and rotate records from the
887                  *       main queue to the retry/hold queues */
888                 wait_event_freezable(kauditd_wait,
889                                      (skb_queue_len(&audit_queue) ? 1 : 0));
890         }
891 
892         return 0;
893 }
894 
895 int audit_send_list(void *_dest)
896 {
897         struct audit_netlink_list *dest = _dest;
898         struct sk_buff *skb;
899         struct sock *sk = audit_get_sk(dest->net);
900 
901         /* wait for parent to finish and send an ACK */
902         audit_ctl_lock();
903         audit_ctl_unlock();
904 
905         while ((skb = __skb_dequeue(&dest->q)) != NULL)
906                 netlink_unicast(sk, skb, dest->portid, 0);
907 
908         put_net(dest->net);
909         kfree(dest);
910 
911         return 0;
912 }
913 
914 struct sk_buff *audit_make_reply(int seq, int type, int done,
915                                  int multi, const void *payload, int size)
916 {
917         struct sk_buff  *skb;
918         struct nlmsghdr *nlh;
919         void            *data;
920         int             flags = multi ? NLM_F_MULTI : 0;
921         int             t     = done  ? NLMSG_DONE  : type;
922 
923         skb = nlmsg_new(size, GFP_KERNEL);
924         if (!skb)
925                 return NULL;
926 
927         nlh     = nlmsg_put(skb, 0, seq, t, size, flags);
928         if (!nlh)
929                 goto out_kfree_skb;
930         data = nlmsg_data(nlh);
931         memcpy(data, payload, size);
932         return skb;
933 
934 out_kfree_skb:
935         kfree_skb(skb);
936         return NULL;
937 }
938 
939 static int audit_send_reply_thread(void *arg)
940 {
941         struct audit_reply *reply = (struct audit_reply *)arg;
942         struct sock *sk = audit_get_sk(reply->net);
943 
944         audit_ctl_lock();
945         audit_ctl_unlock();
946 
947         /* Ignore failure. It'll only happen if the sender goes away,
948            because our timeout is set to infinite. */
949         netlink_unicast(sk, reply->skb, reply->portid, 0);
950         put_net(reply->net);
951         kfree(reply);
952         return 0;
953 }
954 
955 /**
956  * audit_send_reply - send an audit reply message via netlink
957  * @request_skb: skb of request we are replying to (used to target the reply)
958  * @seq: sequence number
959  * @type: audit message type
960  * @done: done (last) flag
961  * @multi: multi-part message flag
962  * @payload: payload data
963  * @size: payload size
964  *
965  * Allocates an skb, builds the netlink message, and sends it to the port id.
966  * No failure notifications.
967  */
968 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
969                              int multi, const void *payload, int size)
970 {
971         struct net *net = sock_net(NETLINK_CB(request_skb).sk);
972         struct sk_buff *skb;
973         struct task_struct *tsk;
974         struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
975                                             GFP_KERNEL);
976 
977         if (!reply)
978                 return;
979 
980         skb = audit_make_reply(seq, type, done, multi, payload, size);
981         if (!skb)
982                 goto out;
983 
984         reply->net = get_net(net);
985         reply->portid = NETLINK_CB(request_skb).portid;
986         reply->skb = skb;
987 
988         tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
989         if (!IS_ERR(tsk))
990                 return;
991         kfree_skb(skb);
992 out:
993         kfree(reply);
994 }
995 
996 /*
997  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
998  * control messages.
999  */
1000 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1001 {
1002         int err = 0;
1003 
1004         /* Only support initial user namespace for now. */
1005         /*
1006          * We return ECONNREFUSED because it tricks userspace into thinking
1007          * that audit was not configured into the kernel.  Lots of users
1008          * configure their PAM stack (because that's what the distro does)
1009          * to reject login if unable to send messages to audit.  If we return
1010          * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1011          * configured in and will let login proceed.  If we return EPERM
1012          * userspace will reject all logins.  This should be removed when we
1013          * support non init namespaces!!
1014          */
1015         if (current_user_ns() != &init_user_ns)
1016                 return -ECONNREFUSED;
1017 
1018         switch (msg_type) {
1019         case AUDIT_LIST:
1020         case AUDIT_ADD:
1021         case AUDIT_DEL:
1022                 return -EOPNOTSUPP;
1023         case AUDIT_GET:
1024         case AUDIT_SET:
1025         case AUDIT_GET_FEATURE:
1026         case AUDIT_SET_FEATURE:
1027         case AUDIT_LIST_RULES:
1028         case AUDIT_ADD_RULE:
1029         case AUDIT_DEL_RULE:
1030         case AUDIT_SIGNAL_INFO:
1031         case AUDIT_TTY_GET:
1032         case AUDIT_TTY_SET:
1033         case AUDIT_TRIM:
1034         case AUDIT_MAKE_EQUIV:
1035                 /* Only support auditd and auditctl in initial pid namespace
1036                  * for now. */
1037                 if (task_active_pid_ns(current) != &init_pid_ns)
1038                         return -EPERM;
1039 
1040                 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1041                         err = -EPERM;
1042                 break;
1043         case AUDIT_USER:
1044         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1045         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1046                 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1047                         err = -EPERM;
1048                 break;
1049         default:  /* bad msg */
1050                 err = -EINVAL;
1051         }
1052 
1053         return err;
1054 }
1055 
1056 static void audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
1057 {
1058         uid_t uid = from_kuid(&init_user_ns, current_uid());
1059         pid_t pid = task_tgid_nr(current);
1060 
1061         if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1062                 *ab = NULL;
1063                 return;
1064         }
1065 
1066         *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
1067         if (unlikely(!*ab))
1068                 return;
1069         audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1070         audit_log_session_info(*ab);
1071         audit_log_task_context(*ab);
1072 }
1073 
1074 int is_audit_feature_set(int i)
1075 {
1076         return af.features & AUDIT_FEATURE_TO_MASK(i);
1077 }
1078 
1079 
1080 static int audit_get_feature(struct sk_buff *skb)
1081 {
1082         u32 seq;
1083 
1084         seq = nlmsg_hdr(skb)->nlmsg_seq;
1085 
1086         audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1087 
1088         return 0;
1089 }
1090 
1091 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1092                                      u32 old_lock, u32 new_lock, int res)
1093 {
1094         struct audit_buffer *ab;
1095 
1096         if (audit_enabled == AUDIT_OFF)
1097                 return;
1098 
1099         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1100         if (!ab)
1101                 return;
1102         audit_log_task_info(ab);
1103         audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1104                          audit_feature_names[which], !!old_feature, !!new_feature,
1105                          !!old_lock, !!new_lock, res);
1106         audit_log_end(ab);
1107 }
1108 
1109 static int audit_set_feature(struct sk_buff *skb)
1110 {
1111         struct audit_features *uaf;
1112         int i;
1113 
1114         BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1115         uaf = nlmsg_data(nlmsg_hdr(skb));
1116 
1117         /* if there is ever a version 2 we should handle that here */
1118 
1119         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1120                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1121                 u32 old_feature, new_feature, old_lock, new_lock;
1122 
1123                 /* if we are not changing this feature, move along */
1124                 if (!(feature & uaf->mask))
1125                         continue;
1126 
1127                 old_feature = af.features & feature;
1128                 new_feature = uaf->features & feature;
1129                 new_lock = (uaf->lock | af.lock) & feature;
1130                 old_lock = af.lock & feature;
1131 
1132                 /* are we changing a locked feature? */
1133                 if (old_lock && (new_feature != old_feature)) {
1134                         audit_log_feature_change(i, old_feature, new_feature,
1135                                                  old_lock, new_lock, 0);
1136                         return -EPERM;
1137                 }
1138         }
1139         /* nothing invalid, do the changes */
1140         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1141                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1142                 u32 old_feature, new_feature, old_lock, new_lock;
1143 
1144                 /* if we are not changing this feature, move along */
1145                 if (!(feature & uaf->mask))
1146                         continue;
1147 
1148                 old_feature = af.features & feature;
1149                 new_feature = uaf->features & feature;
1150                 old_lock = af.lock & feature;
1151                 new_lock = (uaf->lock | af.lock) & feature;
1152 
1153                 if (new_feature != old_feature)
1154                         audit_log_feature_change(i, old_feature, new_feature,
1155                                                  old_lock, new_lock, 1);
1156 
1157                 if (new_feature)
1158                         af.features |= feature;
1159                 else
1160                         af.features &= ~feature;
1161                 af.lock |= new_lock;
1162         }
1163 
1164         return 0;
1165 }
1166 
1167 static int audit_replace(struct pid *pid)
1168 {
1169         pid_t pvnr;
1170         struct sk_buff *skb;
1171 
1172         pvnr = pid_vnr(pid);
1173         skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1174         if (!skb)
1175                 return -ENOMEM;
1176         return auditd_send_unicast_skb(skb);
1177 }
1178 
1179 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
1180 {
1181         u32                     seq;
1182         void                    *data;
1183         int                     err;
1184         struct audit_buffer     *ab;
1185         u16                     msg_type = nlh->nlmsg_type;
1186         struct audit_sig_info   *sig_data;
1187         char                    *ctx = NULL;
1188         u32                     len;
1189 
1190         err = audit_netlink_ok(skb, msg_type);
1191         if (err)
1192                 return err;
1193 
1194         seq  = nlh->nlmsg_seq;
1195         data = nlmsg_data(nlh);
1196 
1197         switch (msg_type) {
1198         case AUDIT_GET: {
1199                 struct audit_status     s;
1200                 memset(&s, 0, sizeof(s));
1201                 s.enabled               = audit_enabled;
1202                 s.failure               = audit_failure;
1203                 /* NOTE: use pid_vnr() so the PID is relative to the current
1204                  *       namespace */
1205                 s.pid                   = auditd_pid_vnr();
1206                 s.rate_limit            = audit_rate_limit;
1207                 s.backlog_limit         = audit_backlog_limit;
1208                 s.lost                  = atomic_read(&audit_lost);
1209                 s.backlog               = skb_queue_len(&audit_queue);
1210                 s.feature_bitmap        = AUDIT_FEATURE_BITMAP_ALL;
1211                 s.backlog_wait_time     = audit_backlog_wait_time;
1212                 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1213                 break;
1214         }
1215         case AUDIT_SET: {
1216                 struct audit_status     s;
1217                 memset(&s, 0, sizeof(s));
1218                 /* guard against past and future API changes */
1219                 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1220                 if (s.mask & AUDIT_STATUS_ENABLED) {
1221                         err = audit_set_enabled(s.enabled);
1222                         if (err < 0)
1223                                 return err;
1224                 }
1225                 if (s.mask & AUDIT_STATUS_FAILURE) {
1226                         err = audit_set_failure(s.failure);
1227                         if (err < 0)
1228                                 return err;
1229                 }
1230                 if (s.mask & AUDIT_STATUS_PID) {
1231                         /* NOTE: we are using the vnr PID functions below
1232                          *       because the s.pid value is relative to the
1233                          *       namespace of the caller; at present this
1234                          *       doesn't matter much since you can really only
1235                          *       run auditd from the initial pid namespace, but
1236                          *       something to keep in mind if this changes */
1237                         pid_t new_pid = s.pid;
1238                         pid_t auditd_pid;
1239                         struct pid *req_pid = task_tgid(current);
1240 
1241                         /* Sanity check - PID values must match. Setting
1242                          * pid to 0 is how auditd ends auditing. */
1243                         if (new_pid && (new_pid != pid_vnr(req_pid)))
1244                                 return -EINVAL;
1245 
1246                         /* test the auditd connection */
1247                         audit_replace(req_pid);
1248 
1249                         auditd_pid = auditd_pid_vnr();
1250                         if (auditd_pid) {
1251                                 /* replacing a healthy auditd is not allowed */
1252                                 if (new_pid) {
1253                                         audit_log_config_change("audit_pid",
1254                                                         new_pid, auditd_pid, 0);
1255                                         return -EEXIST;
1256                                 }
1257                                 /* only current auditd can unregister itself */
1258                                 if (pid_vnr(req_pid) != auditd_pid) {
1259                                         audit_log_config_change("audit_pid",
1260                                                         new_pid, auditd_pid, 0);
1261                                         return -EACCES;
1262                                 }
1263                         }
1264 
1265                         if (new_pid) {
1266                                 /* register a new auditd connection */
1267                                 err = auditd_set(req_pid,
1268                                                  NETLINK_CB(skb).portid,
1269                                                  sock_net(NETLINK_CB(skb).sk));
1270                                 if (audit_enabled != AUDIT_OFF)
1271                                         audit_log_config_change("audit_pid",
1272                                                                 new_pid,
1273                                                                 auditd_pid,
1274                                                                 err ? 0 : 1);
1275                                 if (err)
1276                                         return err;
1277 
1278                                 /* try to process any backlog */
1279                                 wake_up_interruptible(&kauditd_wait);
1280                         } else {
1281                                 if (audit_enabled != AUDIT_OFF)
1282                                         audit_log_config_change("audit_pid",
1283                                                                 new_pid,
1284                                                                 auditd_pid, 1);
1285 
1286                                 /* unregister the auditd connection */
1287                                 auditd_reset(NULL);
1288                         }
1289                 }
1290                 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1291                         err = audit_set_rate_limit(s.rate_limit);
1292                         if (err < 0)
1293                                 return err;
1294                 }
1295                 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1296                         err = audit_set_backlog_limit(s.backlog_limit);
1297                         if (err < 0)
1298                                 return err;
1299                 }
1300                 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1301                         if (sizeof(s) > (size_t)nlh->nlmsg_len)
1302                                 return -EINVAL;
1303                         if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1304                                 return -EINVAL;
1305                         err = audit_set_backlog_wait_time(s.backlog_wait_time);
1306                         if (err < 0)
1307                                 return err;
1308                 }
1309                 if (s.mask == AUDIT_STATUS_LOST) {
1310                         u32 lost = atomic_xchg(&audit_lost, 0);
1311 
1312                         audit_log_config_change("lost", 0, lost, 1);
1313                         return lost;
1314                 }
1315                 break;
1316         }
1317         case AUDIT_GET_FEATURE:
1318                 err = audit_get_feature(skb);
1319                 if (err)
1320                         return err;
1321                 break;
1322         case AUDIT_SET_FEATURE:
1323                 err = audit_set_feature(skb);
1324                 if (err)
1325                         return err;
1326                 break;
1327         case AUDIT_USER:
1328         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1329         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1330                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1331                         return 0;
1332 
1333                 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1334                 if (err == 1) { /* match or error */
1335                         err = 0;
1336                         if (msg_type == AUDIT_USER_TTY) {
1337                                 err = tty_audit_push();
1338                                 if (err)
1339                                         break;
1340                         }
1341                         audit_log_common_recv_msg(&ab, msg_type);
1342                         if (msg_type != AUDIT_USER_TTY)
1343                                 audit_log_format(ab, " msg='%.*s'",
1344                                                  AUDIT_MESSAGE_TEXT_MAX,
1345                                                  (char *)data);
1346                         else {
1347                                 int size;
1348 
1349                                 audit_log_format(ab, " data=");
1350                                 size = nlmsg_len(nlh);
1351                                 if (size > 0 &&
1352                                     ((unsigned char *)data)[size - 1] == '\0')
1353                                         size--;
1354                                 audit_log_n_untrustedstring(ab, data, size);
1355                         }
1356                         audit_log_end(ab);
1357                 }
1358                 break;
1359         case AUDIT_ADD_RULE:
1360         case AUDIT_DEL_RULE:
1361                 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
1362                         return -EINVAL;
1363                 if (audit_enabled == AUDIT_LOCKED) {
1364                         audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1365                         audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
1366                         audit_log_end(ab);
1367                         return -EPERM;
1368                 }
1369                 err = audit_rule_change(msg_type, seq, data, nlmsg_len(nlh));
1370                 break;
1371         case AUDIT_LIST_RULES:
1372                 err = audit_list_rules_send(skb, seq);
1373                 break;
1374         case AUDIT_TRIM:
1375                 audit_trim_trees();
1376                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1377                 audit_log_format(ab, " op=trim res=1");
1378                 audit_log_end(ab);
1379                 break;
1380         case AUDIT_MAKE_EQUIV: {
1381                 void *bufp = data;
1382                 u32 sizes[2];
1383                 size_t msglen = nlmsg_len(nlh);
1384                 char *old, *new;
1385 
1386                 err = -EINVAL;
1387                 if (msglen < 2 * sizeof(u32))
1388                         break;
1389                 memcpy(sizes, bufp, 2 * sizeof(u32));
1390                 bufp += 2 * sizeof(u32);
1391                 msglen -= 2 * sizeof(u32);
1392                 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1393                 if (IS_ERR(old)) {
1394                         err = PTR_ERR(old);
1395                         break;
1396                 }
1397                 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1398                 if (IS_ERR(new)) {
1399                         err = PTR_ERR(new);
1400                         kfree(old);
1401                         break;
1402                 }
1403                 /* OK, here comes... */
1404                 err = audit_tag_tree(old, new);
1405 
1406                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1407 
1408                 audit_log_format(ab, " op=make_equiv old=");
1409                 audit_log_untrustedstring(ab, old);
1410                 audit_log_format(ab, " new=");
1411                 audit_log_untrustedstring(ab, new);
1412                 audit_log_format(ab, " res=%d", !err);
1413                 audit_log_end(ab);
1414                 kfree(old);
1415                 kfree(new);
1416                 break;
1417         }
1418         case AUDIT_SIGNAL_INFO:
1419                 len = 0;
1420                 if (audit_sig_sid) {
1421                         err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1422                         if (err)
1423                                 return err;
1424                 }
1425                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1426                 if (!sig_data) {
1427                         if (audit_sig_sid)
1428                                 security_release_secctx(ctx, len);
1429                         return -ENOMEM;
1430                 }
1431                 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1432                 sig_data->pid = audit_sig_pid;
1433                 if (audit_sig_sid) {
1434                         memcpy(sig_data->ctx, ctx, len);
1435                         security_release_secctx(ctx, len);
1436                 }
1437                 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1438                                  sig_data, sizeof(*sig_data) + len);
1439                 kfree(sig_data);
1440                 break;
1441         case AUDIT_TTY_GET: {
1442                 struct audit_tty_status s;
1443                 unsigned int t;
1444 
1445                 t = READ_ONCE(current->signal->audit_tty);
1446                 s.enabled = t & AUDIT_TTY_ENABLE;
1447                 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1448 
1449                 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1450                 break;
1451         }
1452         case AUDIT_TTY_SET: {
1453                 struct audit_tty_status s, old;
1454                 struct audit_buffer     *ab;
1455                 unsigned int t;
1456 
1457                 memset(&s, 0, sizeof(s));
1458                 /* guard against past and future API changes */
1459                 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1460                 /* check if new data is valid */
1461                 if ((s.enabled != 0 && s.enabled != 1) ||
1462                     (s.log_passwd != 0 && s.log_passwd != 1))
1463                         err = -EINVAL;
1464 
1465                 if (err)
1466                         t = READ_ONCE(current->signal->audit_tty);
1467                 else {
1468                         t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1469                         t = xchg(&current->signal->audit_tty, t);
1470                 }
1471                 old.enabled = t & AUDIT_TTY_ENABLE;
1472                 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1473 
1474                 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1475                 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1476                                  " old-log_passwd=%d new-log_passwd=%d res=%d",
1477                                  old.enabled, s.enabled, old.log_passwd,
1478                                  s.log_passwd, !err);
1479                 audit_log_end(ab);
1480                 break;
1481         }
1482         default:
1483                 err = -EINVAL;
1484                 break;
1485         }
1486 
1487         return err < 0 ? err : 0;
1488 }
1489 
1490 /**
1491  * audit_receive - receive messages from a netlink control socket
1492  * @skb: the message buffer
1493  *
1494  * Parse the provided skb and deal with any messages that may be present,
1495  * malformed skbs are discarded.
1496  */
1497 static void audit_receive(struct sk_buff  *skb)
1498 {
1499         struct nlmsghdr *nlh;
1500         /*
1501          * len MUST be signed for nlmsg_next to be able to dec it below 0
1502          * if the nlmsg_len was not aligned
1503          */
1504         int len;
1505         int err;
1506 
1507         nlh = nlmsg_hdr(skb);
1508         len = skb->len;
1509 
1510         audit_ctl_lock();
1511         while (nlmsg_ok(nlh, len)) {
1512                 err = audit_receive_msg(skb, nlh);
1513                 /* if err or if this message says it wants a response */
1514                 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1515                         netlink_ack(skb, nlh, err, NULL);
1516 
1517                 nlh = nlmsg_next(nlh, &len);
1518         }
1519         audit_ctl_unlock();
1520 }
1521 
1522 /* Run custom bind function on netlink socket group connect or bind requests. */
1523 static int audit_bind(struct net *net, int group)
1524 {
1525         if (!capable(CAP_AUDIT_READ))
1526                 return -EPERM;
1527 
1528         return 0;
1529 }
1530 
1531 static int __net_init audit_net_init(struct net *net)
1532 {
1533         struct netlink_kernel_cfg cfg = {
1534                 .input  = audit_receive,
1535                 .bind   = audit_bind,
1536                 .flags  = NL_CFG_F_NONROOT_RECV,
1537                 .groups = AUDIT_NLGRP_MAX,
1538         };
1539 
1540         struct audit_net *aunet = net_generic(net, audit_net_id);
1541 
1542         aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1543         if (aunet->sk == NULL) {
1544                 audit_panic("cannot initialize netlink socket in namespace");
1545                 return -ENOMEM;
1546         }
1547         aunet->sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1548 
1549         return 0;
1550 }
1551 
1552 static void __net_exit audit_net_exit(struct net *net)
1553 {
1554         struct audit_net *aunet = net_generic(net, audit_net_id);
1555 
1556         /* NOTE: you would think that we would want to check the auditd
1557          * connection and potentially reset it here if it lives in this
1558          * namespace, but since the auditd connection tracking struct holds a
1559          * reference to this namespace (see auditd_set()) we are only ever
1560          * going to get here after that connection has been released */
1561 
1562         netlink_kernel_release(aunet->sk);
1563 }
1564 
1565 static struct pernet_operations audit_net_ops __net_initdata = {
1566         .init = audit_net_init,
1567         .exit = audit_net_exit,
1568         .id = &audit_net_id,
1569         .size = sizeof(struct audit_net),
1570 };
1571 
1572 /* Initialize audit support at boot time. */
1573 static int __init audit_init(void)
1574 {
1575         int i;
1576 
1577         if (audit_initialized == AUDIT_DISABLED)
1578                 return 0;
1579 
1580         audit_buffer_cache = kmem_cache_create("audit_buffer",
1581                                                sizeof(struct audit_buffer),
1582                                                0, SLAB_PANIC, NULL);
1583 
1584         skb_queue_head_init(&audit_queue);
1585         skb_queue_head_init(&audit_retry_queue);
1586         skb_queue_head_init(&audit_hold_queue);
1587 
1588         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1589                 INIT_LIST_HEAD(&audit_inode_hash[i]);
1590 
1591         mutex_init(&audit_cmd_mutex.lock);
1592         audit_cmd_mutex.owner = NULL;
1593 
1594         pr_info("initializing netlink subsys (%s)\n",
1595                 audit_default ? "enabled" : "disabled");
1596         register_pernet_subsys(&audit_net_ops);
1597 
1598         audit_initialized = AUDIT_INITIALIZED;
1599 
1600         kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1601         if (IS_ERR(kauditd_task)) {
1602                 int err = PTR_ERR(kauditd_task);
1603                 panic("audit: failed to start the kauditd thread (%d)\n", err);
1604         }
1605 
1606         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1607                 "state=initialized audit_enabled=%u res=1",
1608                  audit_enabled);
1609 
1610         return 0;
1611 }
1612 postcore_initcall(audit_init);
1613 
1614 /*
1615  * Process kernel command-line parameter at boot time.
1616  * audit={0|off} or audit={1|on}.
1617  */
1618 static int __init audit_enable(char *str)
1619 {
1620         if (!strcasecmp(str, "off") || !strcmp(str, ""))
1621                 audit_default = AUDIT_OFF;
1622         else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1623                 audit_default = AUDIT_ON;
1624         else {
1625                 pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1626                 audit_default = AUDIT_ON;
1627         }
1628 
1629         if (audit_default == AUDIT_OFF)
1630                 audit_initialized = AUDIT_DISABLED;
1631         if (audit_set_enabled(audit_default))
1632                 pr_err("audit: error setting audit state (%d)\n",
1633                        audit_default);
1634 
1635         pr_info("%s\n", audit_default ?
1636                 "enabled (after initialization)" : "disabled (until reboot)");
1637 
1638         return 1;
1639 }
1640 __setup("audit=", audit_enable);
1641 
1642 /* Process kernel command-line parameter at boot time.
1643  * audit_backlog_limit=<n> */
1644 static int __init audit_backlog_limit_set(char *str)
1645 {
1646         u32 audit_backlog_limit_arg;
1647 
1648         pr_info("audit_backlog_limit: ");
1649         if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1650                 pr_cont("using default of %u, unable to parse %s\n",
1651                         audit_backlog_limit, str);
1652                 return 1;
1653         }
1654 
1655         audit_backlog_limit = audit_backlog_limit_arg;
1656         pr_cont("%d\n", audit_backlog_limit);
1657 
1658         return 1;
1659 }
1660 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1661 
1662 static void audit_buffer_free(struct audit_buffer *ab)
1663 {
1664         if (!ab)
1665                 return;
1666 
1667         kfree_skb(ab->skb);
1668         kmem_cache_free(audit_buffer_cache, ab);
1669 }
1670 
1671 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1672                                                gfp_t gfp_mask, int type)
1673 {
1674         struct audit_buffer *ab;
1675 
1676         ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1677         if (!ab)
1678                 return NULL;
1679 
1680         ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1681         if (!ab->skb)
1682                 goto err;
1683         if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1684                 goto err;
1685 
1686         ab->ctx = ctx;
1687         ab->gfp_mask = gfp_mask;
1688 
1689         return ab;
1690 
1691 err:
1692         audit_buffer_free(ab);
1693         return NULL;
1694 }
1695 
1696 /**
1697  * audit_serial - compute a serial number for the audit record
1698  *
1699  * Compute a serial number for the audit record.  Audit records are
1700  * written to user-space as soon as they are generated, so a complete
1701  * audit record may be written in several pieces.  The timestamp of the
1702  * record and this serial number are used by the user-space tools to
1703  * determine which pieces belong to the same audit record.  The
1704  * (timestamp,serial) tuple is unique for each syscall and is live from
1705  * syscall entry to syscall exit.
1706  *
1707  * NOTE: Another possibility is to store the formatted records off the
1708  * audit context (for those records that have a context), and emit them
1709  * all at syscall exit.  However, this could delay the reporting of
1710  * significant errors until syscall exit (or never, if the system
1711  * halts).
1712  */
1713 unsigned int audit_serial(void)
1714 {
1715         static atomic_t serial = ATOMIC_INIT(0);
1716 
1717         return atomic_add_return(1, &serial);
1718 }
1719 
1720 static inline void audit_get_stamp(struct audit_context *ctx,
1721                                    struct timespec64 *t, unsigned int *serial)
1722 {
1723         if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1724                 ktime_get_coarse_real_ts64(t);
1725                 *serial = audit_serial();
1726         }
1727 }
1728 
1729 /**
1730  * audit_log_start - obtain an audit buffer
1731  * @ctx: audit_context (may be NULL)
1732  * @gfp_mask: type of allocation
1733  * @type: audit message type
1734  *
1735  * Returns audit_buffer pointer on success or NULL on error.
1736  *
1737  * Obtain an audit buffer.  This routine does locking to obtain the
1738  * audit buffer, but then no locking is required for calls to
1739  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1740  * syscall, then the syscall is marked as auditable and an audit record
1741  * will be written at syscall exit.  If there is no associated task, then
1742  * task context (ctx) should be NULL.
1743  */
1744 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1745                                      int type)
1746 {
1747         struct audit_buffer *ab;
1748         struct timespec64 t;
1749         unsigned int uninitialized_var(serial);
1750 
1751         if (audit_initialized != AUDIT_INITIALIZED)
1752                 return NULL;
1753 
1754         if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1755                 return NULL;
1756 
1757         /* NOTE: don't ever fail/sleep on these two conditions:
1758          * 1. auditd generated record - since we need auditd to drain the
1759          *    queue; also, when we are checking for auditd, compare PIDs using
1760          *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1761          *    using a PID anchored in the caller's namespace
1762          * 2. generator holding the audit_cmd_mutex - we don't want to block
1763          *    while holding the mutex */
1764         if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1765                 long stime = audit_backlog_wait_time;
1766 
1767                 while (audit_backlog_limit &&
1768                        (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1769                         /* wake kauditd to try and flush the queue */
1770                         wake_up_interruptible(&kauditd_wait);
1771 
1772                         /* sleep if we are allowed and we haven't exhausted our
1773                          * backlog wait limit */
1774                         if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1775                                 DECLARE_WAITQUEUE(wait, current);
1776 
1777                                 add_wait_queue_exclusive(&audit_backlog_wait,
1778                                                          &wait);
1779                                 set_current_state(TASK_UNINTERRUPTIBLE);
1780                                 stime = schedule_timeout(stime);
1781                                 remove_wait_queue(&audit_backlog_wait, &wait);
1782                         } else {
1783                                 if (audit_rate_check() && printk_ratelimit())
1784                                         pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1785                                                 skb_queue_len(&audit_queue),
1786                                                 audit_backlog_limit);
1787                                 audit_log_lost("backlog limit exceeded");
1788                                 return NULL;
1789                         }
1790                 }
1791         }
1792 
1793         ab = audit_buffer_alloc(ctx, gfp_mask, type);
1794         if (!ab) {
1795                 audit_log_lost("out of memory in audit_log_start");
1796                 return NULL;
1797         }
1798 
1799         audit_get_stamp(ab->ctx, &t, &serial);
1800         audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1801                          (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1802 
1803         return ab;
1804 }
1805 
1806 /**
1807  * audit_expand - expand skb in the audit buffer
1808  * @ab: audit_buffer
1809  * @extra: space to add at tail of the skb
1810  *
1811  * Returns 0 (no space) on failed expansion, or available space if
1812  * successful.
1813  */
1814 static inline int audit_expand(struct audit_buffer *ab, int extra)
1815 {
1816         struct sk_buff *skb = ab->skb;
1817         int oldtail = skb_tailroom(skb);
1818         int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1819         int newtail = skb_tailroom(skb);
1820 
1821         if (ret < 0) {
1822                 audit_log_lost("out of memory in audit_expand");
1823                 return 0;
1824         }
1825 
1826         skb->truesize += newtail - oldtail;
1827         return newtail;
1828 }
1829 
1830 /*
1831  * Format an audit message into the audit buffer.  If there isn't enough
1832  * room in the audit buffer, more room will be allocated and vsnprint
1833  * will be called a second time.  Currently, we assume that a printk
1834  * can't format message larger than 1024 bytes, so we don't either.
1835  */
1836 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1837                               va_list args)
1838 {
1839         int len, avail;
1840         struct sk_buff *skb;
1841         va_list args2;
1842 
1843         if (!ab)
1844                 return;
1845 
1846         BUG_ON(!ab->skb);
1847         skb = ab->skb;
1848         avail = skb_tailroom(skb);
1849         if (avail == 0) {
1850                 avail = audit_expand(ab, AUDIT_BUFSIZ);
1851                 if (!avail)
1852                         goto out;
1853         }
1854         va_copy(args2, args);
1855         len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1856         if (len >= avail) {
1857                 /* The printk buffer is 1024 bytes long, so if we get
1858                  * here and AUDIT_BUFSIZ is at least 1024, then we can
1859                  * log everything that printk could have logged. */
1860                 avail = audit_expand(ab,
1861                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1862                 if (!avail)
1863                         goto out_va_end;
1864                 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1865         }
1866         if (len > 0)
1867                 skb_put(skb, len);
1868 out_va_end:
1869         va_end(args2);
1870 out:
1871         return;
1872 }
1873 
1874 /**
1875  * audit_log_format - format a message into the audit buffer.
1876  * @ab: audit_buffer
1877  * @fmt: format string
1878  * @...: optional parameters matching @fmt string
1879  *
1880  * All the work is done in audit_log_vformat.
1881  */
1882 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1883 {
1884         va_list args;
1885 
1886         if (!ab)
1887                 return;
1888         va_start(args, fmt);
1889         audit_log_vformat(ab, fmt, args);
1890         va_end(args);
1891 }
1892 
1893 /**
1894  * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
1895  * @ab: the audit_buffer
1896  * @buf: buffer to convert to hex
1897  * @len: length of @buf to be converted
1898  *
1899  * No return value; failure to expand is silently ignored.
1900  *
1901  * This function will take the passed buf and convert it into a string of
1902  * ascii hex digits. The new string is placed onto the skb.
1903  */
1904 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1905                 size_t len)
1906 {
1907         int i, avail, new_len;
1908         unsigned char *ptr;
1909         struct sk_buff *skb;
1910 
1911         if (!ab)
1912                 return;
1913 
1914         BUG_ON(!ab->skb);
1915         skb = ab->skb;
1916         avail = skb_tailroom(skb);
1917         new_len = len<<1;
1918         if (new_len >= avail) {
1919                 /* Round the buffer request up to the next multiple */
1920                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1921                 avail = audit_expand(ab, new_len);
1922                 if (!avail)
1923                         return;
1924         }
1925 
1926         ptr = skb_tail_pointer(skb);
1927         for (i = 0; i < len; i++)
1928                 ptr = hex_byte_pack_upper(ptr, buf[i]);
1929         *ptr = 0;
1930         skb_put(skb, len << 1); /* new string is twice the old string */
1931 }
1932 
1933 /*
1934  * Format a string of no more than slen characters into the audit buffer,
1935  * enclosed in quote marks.
1936  */
1937 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1938                         size_t slen)
1939 {
1940         int avail, new_len;
1941         unsigned char *ptr;
1942         struct sk_buff *skb;
1943 
1944         if (!ab)
1945                 return;
1946 
1947         BUG_ON(!ab->skb);
1948         skb = ab->skb;
1949         avail = skb_tailroom(skb);
1950         new_len = slen + 3;     /* enclosing quotes + null terminator */
1951         if (new_len > avail) {
1952                 avail = audit_expand(ab, new_len);
1953                 if (!avail)
1954                         return;
1955         }
1956         ptr = skb_tail_pointer(skb);
1957         *ptr++ = '"';
1958         memcpy(ptr, string, slen);
1959         ptr += slen;
1960         *ptr++ = '"';
1961         *ptr = 0;
1962         skb_put(skb, slen + 2); /* don't include null terminator */
1963 }
1964 
1965 /**
1966  * audit_string_contains_control - does a string need to be logged in hex
1967  * @string: string to be checked
1968  * @len: max length of the string to check
1969  */
1970 bool audit_string_contains_control(const char *string, size_t len)
1971 {
1972         const unsigned char *p;
1973         for (p = string; p < (const unsigned char *)string + len; p++) {
1974                 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1975                         return true;
1976         }
1977         return false;
1978 }
1979 
1980 /**
1981  * audit_log_n_untrustedstring - log a string that may contain random characters
1982  * @ab: audit_buffer
1983  * @len: length of string (not including trailing null)
1984  * @string: string to be logged
1985  *
1986  * This code will escape a string that is passed to it if the string
1987  * contains a control character, unprintable character, double quote mark,
1988  * or a space. Unescaped strings will start and end with a double quote mark.
1989  * Strings that are escaped are printed in hex (2 digits per char).
1990  *
1991  * The caller specifies the number of characters in the string to log, which may
1992  * or may not be the entire string.
1993  */
1994 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1995                                  size_t len)
1996 {
1997         if (audit_string_contains_control(string, len))
1998                 audit_log_n_hex(ab, string, len);
1999         else
2000                 audit_log_n_string(ab, string, len);
2001 }
2002 
2003 /**
2004  * audit_log_untrustedstring - log a string that may contain random characters
2005  * @ab: audit_buffer
2006  * @string: string to be logged
2007  *
2008  * Same as audit_log_n_untrustedstring(), except that strlen is used to
2009  * determine string length.
2010  */
2011 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2012 {
2013         audit_log_n_untrustedstring(ab, string, strlen(string));
2014 }
2015 
2016 /* This is a helper-function to print the escaped d_path */
2017 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2018                       const struct path *path)
2019 {
2020         char *p, *pathname;
2021 
2022         if (prefix)
2023                 audit_log_format(ab, "%s", prefix);
2024 
2025         /* We will allow 11 spaces for ' (deleted)' to be appended */
2026         pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2027         if (!pathname) {
2028                 audit_log_string(ab, "<no_memory>");
2029                 return;
2030         }
2031         p = d_path(path, pathname, PATH_MAX+11);
2032         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2033                 /* FIXME: can we save some information here? */
2034                 audit_log_string(ab, "<too_long>");
2035         } else
2036                 audit_log_untrustedstring(ab, p);
2037         kfree(pathname);
2038 }
2039 
2040 void audit_log_session_info(struct audit_buffer *ab)
2041 {
2042         unsigned int sessionid = audit_get_sessionid(current);
2043         uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2044 
2045         audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2046 }
2047 
2048 void audit_log_key(struct audit_buffer *ab, char *key)
2049 {
2050         audit_log_format(ab, " key=");
2051         if (key)
2052                 audit_log_untrustedstring(ab, key);
2053         else
2054                 audit_log_format(ab, "(null)");
2055 }
2056 
2057 void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
2058 {
2059         int i;
2060 
2061         if (cap_isclear(*cap)) {
2062                 audit_log_format(ab, " %s=0", prefix);
2063                 return;
2064         }
2065         audit_log_format(ab, " %s=", prefix);
2066         CAP_FOR_EACH_U32(i)
2067                 audit_log_format(ab, "%08x", cap->cap[CAP_LAST_U32 - i]);
2068 }
2069 
2070 static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
2071 {
2072         audit_log_cap(ab, "cap_fp", &name->fcap.permitted);
2073         audit_log_cap(ab, "cap_fi", &name->fcap.inheritable);
2074         audit_log_format(ab, " cap_fe=%d cap_fver=%x",
2075                          name->fcap.fE, name->fcap_ver);
2076 }
2077 
2078 static inline int audit_copy_fcaps(struct audit_names *name,
2079                                    const struct dentry *dentry)
2080 {
2081         struct cpu_vfs_cap_data caps;
2082         int rc;
2083 
2084         if (!dentry)
2085                 return 0;
2086 
2087         rc = get_vfs_caps_from_disk(dentry, &caps);
2088         if (rc)
2089                 return rc;
2090 
2091         name->fcap.permitted = caps.permitted;
2092         name->fcap.inheritable = caps.inheritable;
2093         name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
2094         name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
2095                                 VFS_CAP_REVISION_SHIFT;
2096 
2097         return 0;
2098 }
2099 
2100 /* Copy inode data into an audit_names. */
2101 void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
2102                       struct inode *inode)
2103 {
2104         name->ino   = inode->i_ino;
2105         name->dev   = inode->i_sb->s_dev;
2106         name->mode  = inode->i_mode;
2107         name->uid   = inode->i_uid;
2108         name->gid   = inode->i_gid;
2109         name->rdev  = inode->i_rdev;
2110         security_inode_getsecid(inode, &name->osid);
2111         audit_copy_fcaps(name, dentry);
2112 }
2113 
2114 /**
2115  * audit_log_name - produce AUDIT_PATH record from struct audit_names
2116  * @context: audit_context for the task
2117  * @n: audit_names structure with reportable details
2118  * @path: optional path to report instead of audit_names->name
2119  * @record_num: record number to report when handling a list of names
2120  * @call_panic: optional pointer to int that will be updated if secid fails
2121  */
2122 void audit_log_name(struct audit_context *context, struct audit_names *n,
2123                     const struct path *path, int record_num, int *call_panic)
2124 {
2125         struct audit_buffer *ab;
2126         ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
2127         if (!ab)
2128                 return;
2129 
2130         audit_log_format(ab, "item=%d", record_num);
2131 
2132         if (path)
2133                 audit_log_d_path(ab, " name=", path);
2134         else if (n->name) {
2135                 switch (n->name_len) {
2136                 case AUDIT_NAME_FULL:
2137                         /* log the full path */
2138                         audit_log_format(ab, " name=");
2139                         audit_log_untrustedstring(ab, n->name->name);
2140                         break;
2141                 case 0:
2142                         /* name was specified as a relative path and the
2143                          * directory component is the cwd */
2144                         audit_log_d_path(ab, " name=", &context->pwd);
2145                         break;
2146                 default:
2147                         /* log the name's directory component */
2148                         audit_log_format(ab, " name=");
2149                         audit_log_n_untrustedstring(ab, n->name->name,
2150                                                     n->name_len);
2151                 }
2152         } else
2153                 audit_log_format(ab, " name=(null)");
2154 
2155         if (n->ino != AUDIT_INO_UNSET)
2156                 audit_log_format(ab, " inode=%lu"
2157                                  " dev=%02x:%02x mode=%#ho"
2158                                  " ouid=%u ogid=%u rdev=%02x:%02x",
2159                                  n->ino,
2160                                  MAJOR(n->dev),
2161                                  MINOR(n->dev),
2162                                  n->mode,
2163                                  from_kuid(&init_user_ns, n->uid),
2164                                  from_kgid(&init_user_ns, n->gid),
2165                                  MAJOR(n->rdev),
2166                                  MINOR(n->rdev));
2167         if (n->osid != 0) {
2168                 char *ctx = NULL;
2169                 u32 len;
2170                 if (security_secid_to_secctx(
2171                         n->osid, &ctx, &len)) {
2172                         audit_log_format(ab, " osid=%u", n->osid);
2173                         if (call_panic)
2174                                 *call_panic = 2;
2175                 } else {
2176                         audit_log_format(ab, " obj=%s", ctx);
2177                         security_release_secctx(ctx, len);
2178                 }
2179         }
2180 
2181         /* log the audit_names record type */
2182         switch(n->type) {
2183         case AUDIT_TYPE_NORMAL:
2184                 audit_log_format(ab, " nametype=NORMAL");
2185                 break;
2186         case AUDIT_TYPE_PARENT:
2187                 audit_log_format(ab, " nametype=PARENT");
2188                 break;
2189         case AUDIT_TYPE_CHILD_DELETE:
2190                 audit_log_format(ab, " nametype=DELETE");
2191                 break;
2192         case AUDIT_TYPE_CHILD_CREATE:
2193                 audit_log_format(ab, " nametype=CREATE");
2194                 break;
2195         default:
2196                 audit_log_format(ab, " nametype=UNKNOWN");
2197                 break;
2198         }
2199 
2200         audit_log_fcaps(ab, n);
2201         audit_log_end(ab);
2202 }
2203 
2204 int audit_log_task_context(struct audit_buffer *ab)
2205 {
2206         char *ctx = NULL;
2207         unsigned len;
2208         int error;
2209         u32 sid;
2210 
2211         security_task_getsecid(current, &sid);
2212         if (!sid)
2213                 return 0;
2214 
2215         error = security_secid_to_secctx(sid, &ctx, &len);
2216         if (error) {
2217                 if (error != -EINVAL)
2218                         goto error_path;
2219                 return 0;
2220         }
2221 
2222         audit_log_format(ab, " subj=%s", ctx);
2223         security_release_secctx(ctx, len);
2224         return 0;
2225 
2226 error_path:
2227         audit_panic("error in audit_log_task_context");
2228         return error;
2229 }
2230 EXPORT_SYMBOL(audit_log_task_context);
2231 
2232 void audit_log_d_path_exe(struct audit_buffer *ab,
2233                           struct mm_struct *mm)
2234 {
2235         struct file *exe_file;
2236 
2237         if (!mm)
2238                 goto out_null;
2239 
2240         exe_file = get_mm_exe_file(mm);
2241         if (!exe_file)
2242                 goto out_null;
2243 
2244         audit_log_d_path(ab, " exe=", &exe_file->f_path);
2245         fput(exe_file);
2246         return;
2247 out_null:
2248         audit_log_format(ab, " exe=(null)");
2249 }
2250 
2251 struct tty_struct *audit_get_tty(void)
2252 {
2253         struct tty_struct *tty = NULL;
2254         unsigned long flags;
2255 
2256         spin_lock_irqsave(&current->sighand->siglock, flags);
2257         if (current->signal)
2258                 tty = tty_kref_get(current->signal->tty);
2259         spin_unlock_irqrestore(&current->sighand->siglock, flags);
2260         return tty;
2261 }
2262 
2263 void audit_put_tty(struct tty_struct *tty)
2264 {
2265         tty_kref_put(tty);
2266 }
2267 
2268 void audit_log_task_info(struct audit_buffer *ab)
2269 {
2270         const struct cred *cred;
2271         char comm[sizeof(current->comm)];
2272         struct tty_struct *tty;
2273 
2274         if (!ab)
2275                 return;
2276 
2277         cred = current_cred();
2278         tty = audit_get_tty();
2279         audit_log_format(ab,
2280                          " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2281                          " euid=%u suid=%u fsuid=%u"
2282                          " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2283                          task_ppid_nr(current),
2284                          task_tgid_nr(current),
2285                          from_kuid(&init_user_ns, audit_get_loginuid(current)),
2286                          from_kuid(&init_user_ns, cred->uid),
2287                          from_kgid(&init_user_ns, cred->gid),
2288                          from_kuid(&init_user_ns, cred->euid),
2289                          from_kuid(&init_user_ns, cred->suid),
2290                          from_kuid(&init_user_ns, cred->fsuid),
2291                          from_kgid(&init_user_ns, cred->egid),
2292                          from_kgid(&init_user_ns, cred->sgid),
2293                          from_kgid(&init_user_ns, cred->fsgid),
2294                          tty ? tty_name(tty) : "(none)",
2295                          audit_get_sessionid(current));
2296         audit_put_tty(tty);
2297         audit_log_format(ab, " comm=");
2298         audit_log_untrustedstring(ab, get_task_comm(comm, current));
2299         audit_log_d_path_exe(ab, current->mm);
2300         audit_log_task_context(ab);
2301 }
2302 EXPORT_SYMBOL(audit_log_task_info);
2303 
2304 /**
2305  * audit_log_link_denied - report a link restriction denial
2306  * @operation: specific link operation
2307  */
2308 void audit_log_link_denied(const char *operation)
2309 {
2310         struct audit_buffer *ab;
2311 
2312         if (!audit_enabled || audit_dummy_context())
2313                 return;
2314 
2315         /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
2316         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_ANOM_LINK);
2317         if (!ab)
2318                 return;
2319         audit_log_format(ab, "op=%s", operation);
2320         audit_log_task_info(ab);
2321         audit_log_format(ab, " res=0");
2322         audit_log_end(ab);
2323 }
2324 
2325 /**
2326  * audit_log_end - end one audit record
2327  * @ab: the audit_buffer
2328  *
2329  * We can not do a netlink send inside an irq context because it blocks (last
2330  * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2331  * queue and a tasklet is scheduled to remove them from the queue outside the
2332  * irq context.  May be called in any context.
2333  */
2334 void audit_log_end(struct audit_buffer *ab)
2335 {
2336         struct sk_buff *skb;
2337         struct nlmsghdr *nlh;
2338 
2339         if (!ab)
2340                 return;
2341 
2342         if (audit_rate_check()) {
2343                 skb = ab->skb;
2344                 ab->skb = NULL;
2345 
2346                 /* setup the netlink header, see the comments in
2347                  * kauditd_send_multicast_skb() for length quirks */
2348                 nlh = nlmsg_hdr(skb);
2349                 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2350 
2351                 /* queue the netlink packet and poke the kauditd thread */
2352                 skb_queue_tail(&audit_queue, skb);
2353                 wake_up_interruptible(&kauditd_wait);
2354         } else
2355                 audit_log_lost("rate limit exceeded");
2356 
2357         audit_buffer_free(ab);
2358 }
2359 
2360 /**
2361  * audit_log - Log an audit record
2362  * @ctx: audit context
2363  * @gfp_mask: type of allocation
2364  * @type: audit message type
2365  * @fmt: format string to use
2366  * @...: variable parameters matching the format string
2367  *
2368  * This is a convenience function that calls audit_log_start,
2369  * audit_log_vformat, and audit_log_end.  It may be called
2370  * in any context.
2371  */
2372 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2373                const char *fmt, ...)
2374 {
2375         struct audit_buffer *ab;
2376         va_list args;
2377 
2378         ab = audit_log_start(ctx, gfp_mask, type);
2379         if (ab) {
2380                 va_start(args, fmt);
2381                 audit_log_vformat(ab, fmt, args);
2382                 va_end(args);
2383                 audit_log_end(ab);
2384         }
2385 }
2386 
2387 EXPORT_SYMBOL(audit_log_start);
2388 EXPORT_SYMBOL(audit_log_end);
2389 EXPORT_SYMBOL(audit_log_format);
2390 EXPORT_SYMBOL(audit_log);
2391 

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