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TOMOYO Linux Cross Reference
Linux/kernel/audit.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /* audit.c -- Auditing support
  3  * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
  4  * System-call specific features have moved to auditsc.c
  5  *
  6  * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
  7  * All Rights Reserved.
  8  *
  9  * Written by Rickard E. (Rik) Faith <faith@redhat.com>
 10  *
 11  * Goals: 1) Integrate fully with Security Modules.
 12  *        2) Minimal run-time overhead:
 13  *           a) Minimal when syscall auditing is disabled (audit_enable=0).
 14  *           b) Small when syscall auditing is enabled and no audit record
 15  *              is generated (defer as much work as possible to record
 16  *              generation time):
 17  *              i) context is allocated,
 18  *              ii) names from getname are stored without a copy, and
 19  *              iii) inode information stored from path_lookup.
 20  *        3) Ability to disable syscall auditing at boot time (audit=0).
 21  *        4) Usable by other parts of the kernel (if audit_log* is called,
 22  *           then a syscall record will be generated automatically for the
 23  *           current syscall).
 24  *        5) Netlink interface to user-space.
 25  *        6) Support low-overhead kernel-based filtering to minimize the
 26  *           information that must be passed to user-space.
 27  *
 28  * Audit userspace, documentation, tests, and bug/issue trackers:
 29  *      https://github.com/linux-audit
 30  */
 31 
 32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 33 
 34 #include <linux/file.h>
 35 #include <linux/init.h>
 36 #include <linux/types.h>
 37 #include <linux/atomic.h>
 38 #include <linux/mm.h>
 39 #include <linux/export.h>
 40 #include <linux/slab.h>
 41 #include <linux/err.h>
 42 #include <linux/kthread.h>
 43 #include <linux/kernel.h>
 44 #include <linux/syscalls.h>
 45 #include <linux/spinlock.h>
 46 #include <linux/rcupdate.h>
 47 #include <linux/mutex.h>
 48 #include <linux/gfp.h>
 49 #include <linux/pid.h>
 50 
 51 #include <linux/audit.h>
 52 
 53 #include <net/sock.h>
 54 #include <net/netlink.h>
 55 #include <linux/skbuff.h>
 56 #ifdef CONFIG_SECURITY
 57 #include <linux/security.h>
 58 #endif
 59 #include <linux/freezer.h>
 60 #include <linux/pid_namespace.h>
 61 #include <net/netns/generic.h>
 62 
 63 #include "audit.h"
 64 
 65 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
 66  * (Initialization happens after skb_init is called.) */
 67 #define AUDIT_DISABLED          -1
 68 #define AUDIT_UNINITIALIZED     0
 69 #define AUDIT_INITIALIZED       1
 70 static int      audit_initialized = AUDIT_UNINITIALIZED;
 71 
 72 u32             audit_enabled = AUDIT_OFF;
 73 bool            audit_ever_enabled = !!AUDIT_OFF;
 74 
 75 EXPORT_SYMBOL_GPL(audit_enabled);
 76 
 77 /* Default state when kernel boots without any parameters. */
 78 static u32      audit_default = AUDIT_OFF;
 79 
 80 /* If auditing cannot proceed, audit_failure selects what happens. */
 81 static u32      audit_failure = AUDIT_FAIL_PRINTK;
 82 
 83 /* private audit network namespace index */
 84 static unsigned int audit_net_id;
 85 
 86 /**
 87  * struct audit_net - audit private network namespace data
 88  * @sk: communication socket
 89  */
 90 struct audit_net {
 91         struct sock *sk;
 92 };
 93 
 94 /**
 95  * struct auditd_connection - kernel/auditd connection state
 96  * @pid: auditd PID
 97  * @portid: netlink portid
 98  * @net: the associated network namespace
 99  * @rcu: RCU head
100  *
101  * Description:
102  * This struct is RCU protected; you must either hold the RCU lock for reading
103  * or the associated spinlock for writing.
104  */
105 struct auditd_connection {
106         struct pid *pid;
107         u32 portid;
108         struct net *net;
109         struct rcu_head rcu;
110 };
111 static struct auditd_connection __rcu *auditd_conn;
112 static DEFINE_SPINLOCK(auditd_conn_lock);
113 
114 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
115  * to that number per second.  This prevents DoS attacks, but results in
116  * audit records being dropped. */
117 static u32      audit_rate_limit;
118 
119 /* Number of outstanding audit_buffers allowed.
120  * When set to zero, this means unlimited. */
121 static u32      audit_backlog_limit = 64;
122 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
123 static u32      audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
124 
125 /* The identity of the user shutting down the audit system. */
126 static kuid_t           audit_sig_uid = INVALID_UID;
127 static pid_t            audit_sig_pid = -1;
128 static u32              audit_sig_sid;
129 
130 /* Records can be lost in several ways:
131    0) [suppressed in audit_alloc]
132    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
133    2) out of memory in audit_log_move [alloc_skb]
134    3) suppressed due to audit_rate_limit
135    4) suppressed due to audit_backlog_limit
136 */
137 static atomic_t audit_lost = ATOMIC_INIT(0);
138 
139 /* Monotonically increasing sum of time the kernel has spent
140  * waiting while the backlog limit is exceeded.
141  */
142 static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
143 
144 /* Hash for inode-based rules */
145 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
146 
147 static struct kmem_cache *audit_buffer_cache;
148 
149 /* queue msgs to send via kauditd_task */
150 static struct sk_buff_head audit_queue;
151 /* queue msgs due to temporary unicast send problems */
152 static struct sk_buff_head audit_retry_queue;
153 /* queue msgs waiting for new auditd connection */
154 static struct sk_buff_head audit_hold_queue;
155 
156 /* queue servicing thread */
157 static struct task_struct *kauditd_task;
158 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
159 
160 /* waitqueue for callers who are blocked on the audit backlog */
161 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
162 
163 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
164                                    .mask = -1,
165                                    .features = 0,
166                                    .lock = 0,};
167 
168 static char *audit_feature_names[2] = {
169         "only_unset_loginuid",
170         "loginuid_immutable",
171 };
172 
173 /**
174  * struct audit_ctl_mutex - serialize requests from userspace
175  * @lock: the mutex used for locking
176  * @owner: the task which owns the lock
177  *
178  * Description:
179  * This is the lock struct used to ensure we only process userspace requests
180  * in an orderly fashion.  We can't simply use a mutex/lock here because we
181  * need to track lock ownership so we don't end up blocking the lock owner in
182  * audit_log_start() or similar.
183  */
184 static struct audit_ctl_mutex {
185         struct mutex lock;
186         void *owner;
187 } audit_cmd_mutex;
188 
189 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
190  * audit records.  Since printk uses a 1024 byte buffer, this buffer
191  * should be at least that large. */
192 #define AUDIT_BUFSIZ 1024
193 
194 /* The audit_buffer is used when formatting an audit record.  The caller
195  * locks briefly to get the record off the freelist or to allocate the
196  * buffer, and locks briefly to send the buffer to the netlink layer or
197  * to place it on a transmit queue.  Multiple audit_buffers can be in
198  * use simultaneously. */
199 struct audit_buffer {
200         struct sk_buff       *skb;      /* formatted skb ready to send */
201         struct audit_context *ctx;      /* NULL or associated context */
202         gfp_t                gfp_mask;
203 };
204 
205 struct audit_reply {
206         __u32 portid;
207         struct net *net;
208         struct sk_buff *skb;
209 };
210 
211 /**
212  * auditd_test_task - Check to see if a given task is an audit daemon
213  * @task: the task to check
214  *
215  * Description:
216  * Return 1 if the task is a registered audit daemon, 0 otherwise.
217  */
218 int auditd_test_task(struct task_struct *task)
219 {
220         int rc;
221         struct auditd_connection *ac;
222 
223         rcu_read_lock();
224         ac = rcu_dereference(auditd_conn);
225         rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
226         rcu_read_unlock();
227 
228         return rc;
229 }
230 
231 /**
232  * audit_ctl_lock - Take the audit control lock
233  */
234 void audit_ctl_lock(void)
235 {
236         mutex_lock(&audit_cmd_mutex.lock);
237         audit_cmd_mutex.owner = current;
238 }
239 
240 /**
241  * audit_ctl_unlock - Drop the audit control lock
242  */
243 void audit_ctl_unlock(void)
244 {
245         audit_cmd_mutex.owner = NULL;
246         mutex_unlock(&audit_cmd_mutex.lock);
247 }
248 
249 /**
250  * audit_ctl_owner_current - Test to see if the current task owns the lock
251  *
252  * Description:
253  * Return true if the current task owns the audit control lock, false if it
254  * doesn't own the lock.
255  */
256 static bool audit_ctl_owner_current(void)
257 {
258         return (current == audit_cmd_mutex.owner);
259 }
260 
261 /**
262  * auditd_pid_vnr - Return the auditd PID relative to the namespace
263  *
264  * Description:
265  * Returns the PID in relation to the namespace, 0 on failure.
266  */
267 static pid_t auditd_pid_vnr(void)
268 {
269         pid_t pid;
270         const struct auditd_connection *ac;
271 
272         rcu_read_lock();
273         ac = rcu_dereference(auditd_conn);
274         if (!ac || !ac->pid)
275                 pid = 0;
276         else
277                 pid = pid_vnr(ac->pid);
278         rcu_read_unlock();
279 
280         return pid;
281 }
282 
283 /**
284  * audit_get_sk - Return the audit socket for the given network namespace
285  * @net: the destination network namespace
286  *
287  * Description:
288  * Returns the sock pointer if valid, NULL otherwise.  The caller must ensure
289  * that a reference is held for the network namespace while the sock is in use.
290  */
291 static struct sock *audit_get_sk(const struct net *net)
292 {
293         struct audit_net *aunet;
294 
295         if (!net)
296                 return NULL;
297 
298         aunet = net_generic(net, audit_net_id);
299         return aunet->sk;
300 }
301 
302 void audit_panic(const char *message)
303 {
304         switch (audit_failure) {
305         case AUDIT_FAIL_SILENT:
306                 break;
307         case AUDIT_FAIL_PRINTK:
308                 if (printk_ratelimit())
309                         pr_err("%s\n", message);
310                 break;
311         case AUDIT_FAIL_PANIC:
312                 panic("audit: %s\n", message);
313                 break;
314         }
315 }
316 
317 static inline int audit_rate_check(void)
318 {
319         static unsigned long    last_check = 0;
320         static int              messages   = 0;
321         static DEFINE_SPINLOCK(lock);
322         unsigned long           flags;
323         unsigned long           now;
324         unsigned long           elapsed;
325         int                     retval     = 0;
326 
327         if (!audit_rate_limit) return 1;
328 
329         spin_lock_irqsave(&lock, flags);
330         if (++messages < audit_rate_limit) {
331                 retval = 1;
332         } else {
333                 now     = jiffies;
334                 elapsed = now - last_check;
335                 if (elapsed > HZ) {
336                         last_check = now;
337                         messages   = 0;
338                         retval     = 1;
339                 }
340         }
341         spin_unlock_irqrestore(&lock, flags);
342 
343         return retval;
344 }
345 
346 /**
347  * audit_log_lost - conditionally log lost audit message event
348  * @message: the message stating reason for lost audit message
349  *
350  * Emit at least 1 message per second, even if audit_rate_check is
351  * throttling.
352  * Always increment the lost messages counter.
353 */
354 void audit_log_lost(const char *message)
355 {
356         static unsigned long    last_msg = 0;
357         static DEFINE_SPINLOCK(lock);
358         unsigned long           flags;
359         unsigned long           now;
360         int                     print;
361 
362         atomic_inc(&audit_lost);
363 
364         print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
365 
366         if (!print) {
367                 spin_lock_irqsave(&lock, flags);
368                 now = jiffies;
369                 if (now - last_msg > HZ) {
370                         print = 1;
371                         last_msg = now;
372                 }
373                 spin_unlock_irqrestore(&lock, flags);
374         }
375 
376         if (print) {
377                 if (printk_ratelimit())
378                         pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
379                                 atomic_read(&audit_lost),
380                                 audit_rate_limit,
381                                 audit_backlog_limit);
382                 audit_panic(message);
383         }
384 }
385 
386 static int audit_log_config_change(char *function_name, u32 new, u32 old,
387                                    int allow_changes)
388 {
389         struct audit_buffer *ab;
390         int rc = 0;
391 
392         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
393         if (unlikely(!ab))
394                 return rc;
395         audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
396         audit_log_session_info(ab);
397         rc = audit_log_task_context(ab);
398         if (rc)
399                 allow_changes = 0; /* Something weird, deny request */
400         audit_log_format(ab, " res=%d", allow_changes);
401         audit_log_end(ab);
402         return rc;
403 }
404 
405 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
406 {
407         int allow_changes, rc = 0;
408         u32 old = *to_change;
409 
410         /* check if we are locked */
411         if (audit_enabled == AUDIT_LOCKED)
412                 allow_changes = 0;
413         else
414                 allow_changes = 1;
415 
416         if (audit_enabled != AUDIT_OFF) {
417                 rc = audit_log_config_change(function_name, new, old, allow_changes);
418                 if (rc)
419                         allow_changes = 0;
420         }
421 
422         /* If we are allowed, make the change */
423         if (allow_changes == 1)
424                 *to_change = new;
425         /* Not allowed, update reason */
426         else if (rc == 0)
427                 rc = -EPERM;
428         return rc;
429 }
430 
431 static int audit_set_rate_limit(u32 limit)
432 {
433         return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
434 }
435 
436 static int audit_set_backlog_limit(u32 limit)
437 {
438         return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
439 }
440 
441 static int audit_set_backlog_wait_time(u32 timeout)
442 {
443         return audit_do_config_change("audit_backlog_wait_time",
444                                       &audit_backlog_wait_time, timeout);
445 }
446 
447 static int audit_set_enabled(u32 state)
448 {
449         int rc;
450         if (state > AUDIT_LOCKED)
451                 return -EINVAL;
452 
453         rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
454         if (!rc)
455                 audit_ever_enabled |= !!state;
456 
457         return rc;
458 }
459 
460 static int audit_set_failure(u32 state)
461 {
462         if (state != AUDIT_FAIL_SILENT
463             && state != AUDIT_FAIL_PRINTK
464             && state != AUDIT_FAIL_PANIC)
465                 return -EINVAL;
466 
467         return audit_do_config_change("audit_failure", &audit_failure, state);
468 }
469 
470 /**
471  * auditd_conn_free - RCU helper to release an auditd connection struct
472  * @rcu: RCU head
473  *
474  * Description:
475  * Drop any references inside the auditd connection tracking struct and free
476  * the memory.
477  */
478 static void auditd_conn_free(struct rcu_head *rcu)
479 {
480         struct auditd_connection *ac;
481 
482         ac = container_of(rcu, struct auditd_connection, rcu);
483         put_pid(ac->pid);
484         put_net(ac->net);
485         kfree(ac);
486 }
487 
488 /**
489  * auditd_set - Set/Reset the auditd connection state
490  * @pid: auditd PID
491  * @portid: auditd netlink portid
492  * @net: auditd network namespace pointer
493  *
494  * Description:
495  * This function will obtain and drop network namespace references as
496  * necessary.  Returns zero on success, negative values on failure.
497  */
498 static int auditd_set(struct pid *pid, u32 portid, struct net *net)
499 {
500         unsigned long flags;
501         struct auditd_connection *ac_old, *ac_new;
502 
503         if (!pid || !net)
504                 return -EINVAL;
505 
506         ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
507         if (!ac_new)
508                 return -ENOMEM;
509         ac_new->pid = get_pid(pid);
510         ac_new->portid = portid;
511         ac_new->net = get_net(net);
512 
513         spin_lock_irqsave(&auditd_conn_lock, flags);
514         ac_old = rcu_dereference_protected(auditd_conn,
515                                            lockdep_is_held(&auditd_conn_lock));
516         rcu_assign_pointer(auditd_conn, ac_new);
517         spin_unlock_irqrestore(&auditd_conn_lock, flags);
518 
519         if (ac_old)
520                 call_rcu(&ac_old->rcu, auditd_conn_free);
521 
522         return 0;
523 }
524 
525 /**
526  * kauditd_printk_skb - Print the audit record to the ring buffer
527  * @skb: audit record
528  *
529  * Whatever the reason, this packet may not make it to the auditd connection
530  * so write it via printk so the information isn't completely lost.
531  */
532 static void kauditd_printk_skb(struct sk_buff *skb)
533 {
534         struct nlmsghdr *nlh = nlmsg_hdr(skb);
535         char *data = nlmsg_data(nlh);
536 
537         if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
538                 pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
539 }
540 
541 /**
542  * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
543  * @skb: audit record
544  * @error: error code (unused)
545  *
546  * Description:
547  * This should only be used by the kauditd_thread when it fails to flush the
548  * hold queue.
549  */
550 static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error)
551 {
552         /* put the record back in the queue */
553         skb_queue_tail(&audit_hold_queue, skb);
554 }
555 
556 /**
557  * kauditd_hold_skb - Queue an audit record, waiting for auditd
558  * @skb: audit record
559  * @error: error code
560  *
561  * Description:
562  * Queue the audit record, waiting for an instance of auditd.  When this
563  * function is called we haven't given up yet on sending the record, but things
564  * are not looking good.  The first thing we want to do is try to write the
565  * record via printk and then see if we want to try and hold on to the record
566  * and queue it, if we have room.  If we want to hold on to the record, but we
567  * don't have room, record a record lost message.
568  */
569 static void kauditd_hold_skb(struct sk_buff *skb, int error)
570 {
571         /* at this point it is uncertain if we will ever send this to auditd so
572          * try to send the message via printk before we go any further */
573         kauditd_printk_skb(skb);
574 
575         /* can we just silently drop the message? */
576         if (!audit_default)
577                 goto drop;
578 
579         /* the hold queue is only for when the daemon goes away completely,
580          * not -EAGAIN failures; if we are in a -EAGAIN state requeue the
581          * record on the retry queue unless it's full, in which case drop it
582          */
583         if (error == -EAGAIN) {
584                 if (!audit_backlog_limit ||
585                     skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
586                         skb_queue_tail(&audit_retry_queue, skb);
587                         return;
588                 }
589                 audit_log_lost("kauditd retry queue overflow");
590                 goto drop;
591         }
592 
593         /* if we have room in the hold queue, queue the message */
594         if (!audit_backlog_limit ||
595             skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
596                 skb_queue_tail(&audit_hold_queue, skb);
597                 return;
598         }
599 
600         /* we have no other options - drop the message */
601         audit_log_lost("kauditd hold queue overflow");
602 drop:
603         kfree_skb(skb);
604 }
605 
606 /**
607  * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
608  * @skb: audit record
609  * @error: error code (unused)
610  *
611  * Description:
612  * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
613  * but for some reason we are having problems sending it audit records so
614  * queue the given record and attempt to resend.
615  */
616 static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
617 {
618         if (!audit_backlog_limit ||
619             skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
620                 skb_queue_tail(&audit_retry_queue, skb);
621                 return;
622         }
623 
624         /* we have to drop the record, send it via printk as a last effort */
625         kauditd_printk_skb(skb);
626         audit_log_lost("kauditd retry queue overflow");
627         kfree_skb(skb);
628 }
629 
630 /**
631  * auditd_reset - Disconnect the auditd connection
632  * @ac: auditd connection state
633  *
634  * Description:
635  * Break the auditd/kauditd connection and move all the queued records into the
636  * hold queue in case auditd reconnects.  It is important to note that the @ac
637  * pointer should never be dereferenced inside this function as it may be NULL
638  * or invalid, you can only compare the memory address!  If @ac is NULL then
639  * the connection will always be reset.
640  */
641 static void auditd_reset(const struct auditd_connection *ac)
642 {
643         unsigned long flags;
644         struct sk_buff *skb;
645         struct auditd_connection *ac_old;
646 
647         /* if it isn't already broken, break the connection */
648         spin_lock_irqsave(&auditd_conn_lock, flags);
649         ac_old = rcu_dereference_protected(auditd_conn,
650                                            lockdep_is_held(&auditd_conn_lock));
651         if (ac && ac != ac_old) {
652                 /* someone already registered a new auditd connection */
653                 spin_unlock_irqrestore(&auditd_conn_lock, flags);
654                 return;
655         }
656         rcu_assign_pointer(auditd_conn, NULL);
657         spin_unlock_irqrestore(&auditd_conn_lock, flags);
658 
659         if (ac_old)
660                 call_rcu(&ac_old->rcu, auditd_conn_free);
661 
662         /* flush the retry queue to the hold queue, but don't touch the main
663          * queue since we need to process that normally for multicast */
664         while ((skb = skb_dequeue(&audit_retry_queue)))
665                 kauditd_hold_skb(skb, -ECONNREFUSED);
666 }
667 
668 /**
669  * auditd_send_unicast_skb - Send a record via unicast to auditd
670  * @skb: audit record
671  *
672  * Description:
673  * Send a skb to the audit daemon, returns positive/zero values on success and
674  * negative values on failure; in all cases the skb will be consumed by this
675  * function.  If the send results in -ECONNREFUSED the connection with auditd
676  * will be reset.  This function may sleep so callers should not hold any locks
677  * where this would cause a problem.
678  */
679 static int auditd_send_unicast_skb(struct sk_buff *skb)
680 {
681         int rc;
682         u32 portid;
683         struct net *net;
684         struct sock *sk;
685         struct auditd_connection *ac;
686 
687         /* NOTE: we can't call netlink_unicast while in the RCU section so
688          *       take a reference to the network namespace and grab local
689          *       copies of the namespace, the sock, and the portid; the
690          *       namespace and sock aren't going to go away while we hold a
691          *       reference and if the portid does become invalid after the RCU
692          *       section netlink_unicast() should safely return an error */
693 
694         rcu_read_lock();
695         ac = rcu_dereference(auditd_conn);
696         if (!ac) {
697                 rcu_read_unlock();
698                 kfree_skb(skb);
699                 rc = -ECONNREFUSED;
700                 goto err;
701         }
702         net = get_net(ac->net);
703         sk = audit_get_sk(net);
704         portid = ac->portid;
705         rcu_read_unlock();
706 
707         rc = netlink_unicast(sk, skb, portid, 0);
708         put_net(net);
709         if (rc < 0)
710                 goto err;
711 
712         return rc;
713 
714 err:
715         if (ac && rc == -ECONNREFUSED)
716                 auditd_reset(ac);
717         return rc;
718 }
719 
720 /**
721  * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
722  * @sk: the sending sock
723  * @portid: the netlink destination
724  * @queue: the skb queue to process
725  * @retry_limit: limit on number of netlink unicast failures
726  * @skb_hook: per-skb hook for additional processing
727  * @err_hook: hook called if the skb fails the netlink unicast send
728  *
729  * Description:
730  * Run through the given queue and attempt to send the audit records to auditd,
731  * returns zero on success, negative values on failure.  It is up to the caller
732  * to ensure that the @sk is valid for the duration of this function.
733  *
734  */
735 static int kauditd_send_queue(struct sock *sk, u32 portid,
736                               struct sk_buff_head *queue,
737                               unsigned int retry_limit,
738                               void (*skb_hook)(struct sk_buff *skb),
739                               void (*err_hook)(struct sk_buff *skb, int error))
740 {
741         int rc = 0;
742         struct sk_buff *skb = NULL;
743         struct sk_buff *skb_tail;
744         unsigned int failed = 0;
745 
746         /* NOTE: kauditd_thread takes care of all our locking, we just use
747          *       the netlink info passed to us (e.g. sk and portid) */
748 
749         skb_tail = skb_peek_tail(queue);
750         while ((skb != skb_tail) && (skb = skb_dequeue(queue))) {
751                 /* call the skb_hook for each skb we touch */
752                 if (skb_hook)
753                         (*skb_hook)(skb);
754 
755                 /* can we send to anyone via unicast? */
756                 if (!sk) {
757                         if (err_hook)
758                                 (*err_hook)(skb, -ECONNREFUSED);
759                         continue;
760                 }
761 
762 retry:
763                 /* grab an extra skb reference in case of error */
764                 skb_get(skb);
765                 rc = netlink_unicast(sk, skb, portid, 0);
766                 if (rc < 0) {
767                         /* send failed - try a few times unless fatal error */
768                         if (++failed >= retry_limit ||
769                             rc == -ECONNREFUSED || rc == -EPERM) {
770                                 sk = NULL;
771                                 if (err_hook)
772                                         (*err_hook)(skb, rc);
773                                 if (rc == -EAGAIN)
774                                         rc = 0;
775                                 /* continue to drain the queue */
776                                 continue;
777                         } else
778                                 goto retry;
779                 } else {
780                         /* skb sent - drop the extra reference and continue */
781                         consume_skb(skb);
782                         failed = 0;
783                 }
784         }
785 
786         return (rc >= 0 ? 0 : rc);
787 }
788 
789 /*
790  * kauditd_send_multicast_skb - Send a record to any multicast listeners
791  * @skb: audit record
792  *
793  * Description:
794  * Write a multicast message to anyone listening in the initial network
795  * namespace.  This function doesn't consume an skb as might be expected since
796  * it has to copy it anyways.
797  */
798 static void kauditd_send_multicast_skb(struct sk_buff *skb)
799 {
800         struct sk_buff *copy;
801         struct sock *sock = audit_get_sk(&init_net);
802         struct nlmsghdr *nlh;
803 
804         /* NOTE: we are not taking an additional reference for init_net since
805          *       we don't have to worry about it going away */
806 
807         if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
808                 return;
809 
810         /*
811          * The seemingly wasteful skb_copy() rather than bumping the refcount
812          * using skb_get() is necessary because non-standard mods are made to
813          * the skb by the original kaudit unicast socket send routine.  The
814          * existing auditd daemon assumes this breakage.  Fixing this would
815          * require co-ordinating a change in the established protocol between
816          * the kaudit kernel subsystem and the auditd userspace code.  There is
817          * no reason for new multicast clients to continue with this
818          * non-compliance.
819          */
820         copy = skb_copy(skb, GFP_KERNEL);
821         if (!copy)
822                 return;
823         nlh = nlmsg_hdr(copy);
824         nlh->nlmsg_len = skb->len;
825 
826         nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
827 }
828 
829 /**
830  * kauditd_thread - Worker thread to send audit records to userspace
831  * @dummy: unused
832  */
833 static int kauditd_thread(void *dummy)
834 {
835         int rc;
836         u32 portid = 0;
837         struct net *net = NULL;
838         struct sock *sk = NULL;
839         struct auditd_connection *ac;
840 
841 #define UNICAST_RETRIES 5
842 
843         set_freezable();
844         while (!kthread_should_stop()) {
845                 /* NOTE: see the lock comments in auditd_send_unicast_skb() */
846                 rcu_read_lock();
847                 ac = rcu_dereference(auditd_conn);
848                 if (!ac) {
849                         rcu_read_unlock();
850                         goto main_queue;
851                 }
852                 net = get_net(ac->net);
853                 sk = audit_get_sk(net);
854                 portid = ac->portid;
855                 rcu_read_unlock();
856 
857                 /* attempt to flush the hold queue */
858                 rc = kauditd_send_queue(sk, portid,
859                                         &audit_hold_queue, UNICAST_RETRIES,
860                                         NULL, kauditd_rehold_skb);
861                 if (rc < 0) {
862                         sk = NULL;
863                         auditd_reset(ac);
864                         goto main_queue;
865                 }
866 
867                 /* attempt to flush the retry queue */
868                 rc = kauditd_send_queue(sk, portid,
869                                         &audit_retry_queue, UNICAST_RETRIES,
870                                         NULL, kauditd_hold_skb);
871                 if (rc < 0) {
872                         sk = NULL;
873                         auditd_reset(ac);
874                         goto main_queue;
875                 }
876 
877 main_queue:
878                 /* process the main queue - do the multicast send and attempt
879                  * unicast, dump failed record sends to the retry queue; if
880                  * sk == NULL due to previous failures we will just do the
881                  * multicast send and move the record to the hold queue */
882                 rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
883                                         kauditd_send_multicast_skb,
884                                         (sk ?
885                                          kauditd_retry_skb : kauditd_hold_skb));
886                 if (ac && rc < 0)
887                         auditd_reset(ac);
888                 sk = NULL;
889 
890                 /* drop our netns reference, no auditd sends past this line */
891                 if (net) {
892                         put_net(net);
893                         net = NULL;
894                 }
895 
896                 /* we have processed all the queues so wake everyone */
897                 wake_up(&audit_backlog_wait);
898 
899                 /* NOTE: we want to wake up if there is anything on the queue,
900                  *       regardless of if an auditd is connected, as we need to
901                  *       do the multicast send and rotate records from the
902                  *       main queue to the retry/hold queues */
903                 wait_event_freezable(kauditd_wait,
904                                      (skb_queue_len(&audit_queue) ? 1 : 0));
905         }
906 
907         return 0;
908 }
909 
910 int audit_send_list_thread(void *_dest)
911 {
912         struct audit_netlink_list *dest = _dest;
913         struct sk_buff *skb;
914         struct sock *sk = audit_get_sk(dest->net);
915 
916         /* wait for parent to finish and send an ACK */
917         audit_ctl_lock();
918         audit_ctl_unlock();
919 
920         while ((skb = __skb_dequeue(&dest->q)) != NULL)
921                 netlink_unicast(sk, skb, dest->portid, 0);
922 
923         put_net(dest->net);
924         kfree(dest);
925 
926         return 0;
927 }
928 
929 struct sk_buff *audit_make_reply(int seq, int type, int done,
930                                  int multi, const void *payload, int size)
931 {
932         struct sk_buff  *skb;
933         struct nlmsghdr *nlh;
934         void            *data;
935         int             flags = multi ? NLM_F_MULTI : 0;
936         int             t     = done  ? NLMSG_DONE  : type;
937 
938         skb = nlmsg_new(size, GFP_KERNEL);
939         if (!skb)
940                 return NULL;
941 
942         nlh     = nlmsg_put(skb, 0, seq, t, size, flags);
943         if (!nlh)
944                 goto out_kfree_skb;
945         data = nlmsg_data(nlh);
946         memcpy(data, payload, size);
947         return skb;
948 
949 out_kfree_skb:
950         kfree_skb(skb);
951         return NULL;
952 }
953 
954 static void audit_free_reply(struct audit_reply *reply)
955 {
956         if (!reply)
957                 return;
958 
959         kfree_skb(reply->skb);
960         if (reply->net)
961                 put_net(reply->net);
962         kfree(reply);
963 }
964 
965 static int audit_send_reply_thread(void *arg)
966 {
967         struct audit_reply *reply = (struct audit_reply *)arg;
968 
969         audit_ctl_lock();
970         audit_ctl_unlock();
971 
972         /* Ignore failure. It'll only happen if the sender goes away,
973            because our timeout is set to infinite. */
974         netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
975         reply->skb = NULL;
976         audit_free_reply(reply);
977         return 0;
978 }
979 
980 /**
981  * audit_send_reply - send an audit reply message via netlink
982  * @request_skb: skb of request we are replying to (used to target the reply)
983  * @seq: sequence number
984  * @type: audit message type
985  * @done: done (last) flag
986  * @multi: multi-part message flag
987  * @payload: payload data
988  * @size: payload size
989  *
990  * Allocates a skb, builds the netlink message, and sends it to the port id.
991  */
992 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
993                              int multi, const void *payload, int size)
994 {
995         struct task_struct *tsk;
996         struct audit_reply *reply;
997 
998         reply = kzalloc(sizeof(*reply), GFP_KERNEL);
999         if (!reply)
1000                 return;
1001 
1002         reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
1003         if (!reply->skb)
1004                 goto err;
1005         reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
1006         reply->portid = NETLINK_CB(request_skb).portid;
1007 
1008         tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
1009         if (IS_ERR(tsk))
1010                 goto err;
1011 
1012         return;
1013 
1014 err:
1015         audit_free_reply(reply);
1016 }
1017 
1018 /*
1019  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
1020  * control messages.
1021  */
1022 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1023 {
1024         int err = 0;
1025 
1026         /* Only support initial user namespace for now. */
1027         /*
1028          * We return ECONNREFUSED because it tricks userspace into thinking
1029          * that audit was not configured into the kernel.  Lots of users
1030          * configure their PAM stack (because that's what the distro does)
1031          * to reject login if unable to send messages to audit.  If we return
1032          * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1033          * configured in and will let login proceed.  If we return EPERM
1034          * userspace will reject all logins.  This should be removed when we
1035          * support non init namespaces!!
1036          */
1037         if (current_user_ns() != &init_user_ns)
1038                 return -ECONNREFUSED;
1039 
1040         switch (msg_type) {
1041         case AUDIT_LIST:
1042         case AUDIT_ADD:
1043         case AUDIT_DEL:
1044                 return -EOPNOTSUPP;
1045         case AUDIT_GET:
1046         case AUDIT_SET:
1047         case AUDIT_GET_FEATURE:
1048         case AUDIT_SET_FEATURE:
1049         case AUDIT_LIST_RULES:
1050         case AUDIT_ADD_RULE:
1051         case AUDIT_DEL_RULE:
1052         case AUDIT_SIGNAL_INFO:
1053         case AUDIT_TTY_GET:
1054         case AUDIT_TTY_SET:
1055         case AUDIT_TRIM:
1056         case AUDIT_MAKE_EQUIV:
1057                 /* Only support auditd and auditctl in initial pid namespace
1058                  * for now. */
1059                 if (task_active_pid_ns(current) != &init_pid_ns)
1060                         return -EPERM;
1061 
1062                 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1063                         err = -EPERM;
1064                 break;
1065         case AUDIT_USER:
1066         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1067         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1068                 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1069                         err = -EPERM;
1070                 break;
1071         default:  /* bad msg */
1072                 err = -EINVAL;
1073         }
1074 
1075         return err;
1076 }
1077 
1078 static void audit_log_common_recv_msg(struct audit_context *context,
1079                                         struct audit_buffer **ab, u16 msg_type)
1080 {
1081         uid_t uid = from_kuid(&init_user_ns, current_uid());
1082         pid_t pid = task_tgid_nr(current);
1083 
1084         if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1085                 *ab = NULL;
1086                 return;
1087         }
1088 
1089         *ab = audit_log_start(context, GFP_KERNEL, msg_type);
1090         if (unlikely(!*ab))
1091                 return;
1092         audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1093         audit_log_session_info(*ab);
1094         audit_log_task_context(*ab);
1095 }
1096 
1097 static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1098                                            u16 msg_type)
1099 {
1100         audit_log_common_recv_msg(NULL, ab, msg_type);
1101 }
1102 
1103 int is_audit_feature_set(int i)
1104 {
1105         return af.features & AUDIT_FEATURE_TO_MASK(i);
1106 }
1107 
1108 
1109 static int audit_get_feature(struct sk_buff *skb)
1110 {
1111         u32 seq;
1112 
1113         seq = nlmsg_hdr(skb)->nlmsg_seq;
1114 
1115         audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1116 
1117         return 0;
1118 }
1119 
1120 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1121                                      u32 old_lock, u32 new_lock, int res)
1122 {
1123         struct audit_buffer *ab;
1124 
1125         if (audit_enabled == AUDIT_OFF)
1126                 return;
1127 
1128         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1129         if (!ab)
1130                 return;
1131         audit_log_task_info(ab);
1132         audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1133                          audit_feature_names[which], !!old_feature, !!new_feature,
1134                          !!old_lock, !!new_lock, res);
1135         audit_log_end(ab);
1136 }
1137 
1138 static int audit_set_feature(struct audit_features *uaf)
1139 {
1140         int i;
1141 
1142         BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1143 
1144         /* if there is ever a version 2 we should handle that here */
1145 
1146         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1147                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1148                 u32 old_feature, new_feature, old_lock, new_lock;
1149 
1150                 /* if we are not changing this feature, move along */
1151                 if (!(feature & uaf->mask))
1152                         continue;
1153 
1154                 old_feature = af.features & feature;
1155                 new_feature = uaf->features & feature;
1156                 new_lock = (uaf->lock | af.lock) & feature;
1157                 old_lock = af.lock & feature;
1158 
1159                 /* are we changing a locked feature? */
1160                 if (old_lock && (new_feature != old_feature)) {
1161                         audit_log_feature_change(i, old_feature, new_feature,
1162                                                  old_lock, new_lock, 0);
1163                         return -EPERM;
1164                 }
1165         }
1166         /* nothing invalid, do the changes */
1167         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1168                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1169                 u32 old_feature, new_feature, old_lock, new_lock;
1170 
1171                 /* if we are not changing this feature, move along */
1172                 if (!(feature & uaf->mask))
1173                         continue;
1174 
1175                 old_feature = af.features & feature;
1176                 new_feature = uaf->features & feature;
1177                 old_lock = af.lock & feature;
1178                 new_lock = (uaf->lock | af.lock) & feature;
1179 
1180                 if (new_feature != old_feature)
1181                         audit_log_feature_change(i, old_feature, new_feature,
1182                                                  old_lock, new_lock, 1);
1183 
1184                 if (new_feature)
1185                         af.features |= feature;
1186                 else
1187                         af.features &= ~feature;
1188                 af.lock |= new_lock;
1189         }
1190 
1191         return 0;
1192 }
1193 
1194 static int audit_replace(struct pid *pid)
1195 {
1196         pid_t pvnr;
1197         struct sk_buff *skb;
1198 
1199         pvnr = pid_vnr(pid);
1200         skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1201         if (!skb)
1202                 return -ENOMEM;
1203         return auditd_send_unicast_skb(skb);
1204 }
1205 
1206 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
1207 {
1208         u32                     seq;
1209         void                    *data;
1210         int                     data_len;
1211         int                     err;
1212         struct audit_buffer     *ab;
1213         u16                     msg_type = nlh->nlmsg_type;
1214         struct audit_sig_info   *sig_data;
1215         char                    *ctx = NULL;
1216         u32                     len;
1217 
1218         err = audit_netlink_ok(skb, msg_type);
1219         if (err)
1220                 return err;
1221 
1222         seq  = nlh->nlmsg_seq;
1223         data = nlmsg_data(nlh);
1224         data_len = nlmsg_len(nlh);
1225 
1226         switch (msg_type) {
1227         case AUDIT_GET: {
1228                 struct audit_status     s;
1229                 memset(&s, 0, sizeof(s));
1230                 s.enabled                  = audit_enabled;
1231                 s.failure                  = audit_failure;
1232                 /* NOTE: use pid_vnr() so the PID is relative to the current
1233                  *       namespace */
1234                 s.pid                      = auditd_pid_vnr();
1235                 s.rate_limit               = audit_rate_limit;
1236                 s.backlog_limit            = audit_backlog_limit;
1237                 s.lost                     = atomic_read(&audit_lost);
1238                 s.backlog                  = skb_queue_len(&audit_queue);
1239                 s.feature_bitmap           = AUDIT_FEATURE_BITMAP_ALL;
1240                 s.backlog_wait_time        = audit_backlog_wait_time;
1241                 s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1242                 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1243                 break;
1244         }
1245         case AUDIT_SET: {
1246                 struct audit_status     s;
1247                 memset(&s, 0, sizeof(s));
1248                 /* guard against past and future API changes */
1249                 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1250                 if (s.mask & AUDIT_STATUS_ENABLED) {
1251                         err = audit_set_enabled(s.enabled);
1252                         if (err < 0)
1253                                 return err;
1254                 }
1255                 if (s.mask & AUDIT_STATUS_FAILURE) {
1256                         err = audit_set_failure(s.failure);
1257                         if (err < 0)
1258                                 return err;
1259                 }
1260                 if (s.mask & AUDIT_STATUS_PID) {
1261                         /* NOTE: we are using the vnr PID functions below
1262                          *       because the s.pid value is relative to the
1263                          *       namespace of the caller; at present this
1264                          *       doesn't matter much since you can really only
1265                          *       run auditd from the initial pid namespace, but
1266                          *       something to keep in mind if this changes */
1267                         pid_t new_pid = s.pid;
1268                         pid_t auditd_pid;
1269                         struct pid *req_pid = task_tgid(current);
1270 
1271                         /* Sanity check - PID values must match. Setting
1272                          * pid to 0 is how auditd ends auditing. */
1273                         if (new_pid && (new_pid != pid_vnr(req_pid)))
1274                                 return -EINVAL;
1275 
1276                         /* test the auditd connection */
1277                         audit_replace(req_pid);
1278 
1279                         auditd_pid = auditd_pid_vnr();
1280                         if (auditd_pid) {
1281                                 /* replacing a healthy auditd is not allowed */
1282                                 if (new_pid) {
1283                                         audit_log_config_change("audit_pid",
1284                                                         new_pid, auditd_pid, 0);
1285                                         return -EEXIST;
1286                                 }
1287                                 /* only current auditd can unregister itself */
1288                                 if (pid_vnr(req_pid) != auditd_pid) {
1289                                         audit_log_config_change("audit_pid",
1290                                                         new_pid, auditd_pid, 0);
1291                                         return -EACCES;
1292                                 }
1293                         }
1294 
1295                         if (new_pid) {
1296                                 /* register a new auditd connection */
1297                                 err = auditd_set(req_pid,
1298                                                  NETLINK_CB(skb).portid,
1299                                                  sock_net(NETLINK_CB(skb).sk));
1300                                 if (audit_enabled != AUDIT_OFF)
1301                                         audit_log_config_change("audit_pid",
1302                                                                 new_pid,
1303                                                                 auditd_pid,
1304                                                                 err ? 0 : 1);
1305                                 if (err)
1306                                         return err;
1307 
1308                                 /* try to process any backlog */
1309                                 wake_up_interruptible(&kauditd_wait);
1310                         } else {
1311                                 if (audit_enabled != AUDIT_OFF)
1312                                         audit_log_config_change("audit_pid",
1313                                                                 new_pid,
1314                                                                 auditd_pid, 1);
1315 
1316                                 /* unregister the auditd connection */
1317                                 auditd_reset(NULL);
1318                         }
1319                 }
1320                 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1321                         err = audit_set_rate_limit(s.rate_limit);
1322                         if (err < 0)
1323                                 return err;
1324                 }
1325                 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1326                         err = audit_set_backlog_limit(s.backlog_limit);
1327                         if (err < 0)
1328                                 return err;
1329                 }
1330                 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1331                         if (sizeof(s) > (size_t)nlh->nlmsg_len)
1332                                 return -EINVAL;
1333                         if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1334                                 return -EINVAL;
1335                         err = audit_set_backlog_wait_time(s.backlog_wait_time);
1336                         if (err < 0)
1337                                 return err;
1338                 }
1339                 if (s.mask == AUDIT_STATUS_LOST) {
1340                         u32 lost = atomic_xchg(&audit_lost, 0);
1341 
1342                         audit_log_config_change("lost", 0, lost, 1);
1343                         return lost;
1344                 }
1345                 if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1346                         u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1347 
1348                         audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1349                         return actual;
1350                 }
1351                 break;
1352         }
1353         case AUDIT_GET_FEATURE:
1354                 err = audit_get_feature(skb);
1355                 if (err)
1356                         return err;
1357                 break;
1358         case AUDIT_SET_FEATURE:
1359                 if (data_len < sizeof(struct audit_features))
1360                         return -EINVAL;
1361                 err = audit_set_feature(data);
1362                 if (err)
1363                         return err;
1364                 break;
1365         case AUDIT_USER:
1366         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1367         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1368                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1369                         return 0;
1370                 /* exit early if there isn't at least one character to print */
1371                 if (data_len < 2)
1372                         return -EINVAL;
1373 
1374                 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1375                 if (err == 1) { /* match or error */
1376                         char *str = data;
1377 
1378                         err = 0;
1379                         if (msg_type == AUDIT_USER_TTY) {
1380                                 err = tty_audit_push();
1381                                 if (err)
1382                                         break;
1383                         }
1384                         audit_log_user_recv_msg(&ab, msg_type);
1385                         if (msg_type != AUDIT_USER_TTY) {
1386                                 /* ensure NULL termination */
1387                                 str[data_len - 1] = '\0';
1388                                 audit_log_format(ab, " msg='%.*s'",
1389                                                  AUDIT_MESSAGE_TEXT_MAX,
1390                                                  str);
1391                         } else {
1392                                 audit_log_format(ab, " data=");
1393                                 if (data_len > 0 && str[data_len - 1] == '\0')
1394                                         data_len--;
1395                                 audit_log_n_untrustedstring(ab, str, data_len);
1396                         }
1397                         audit_log_end(ab);
1398                 }
1399                 break;
1400         case AUDIT_ADD_RULE:
1401         case AUDIT_DEL_RULE:
1402                 if (data_len < sizeof(struct audit_rule_data))
1403                         return -EINVAL;
1404                 if (audit_enabled == AUDIT_LOCKED) {
1405                         audit_log_common_recv_msg(audit_context(), &ab,
1406                                                   AUDIT_CONFIG_CHANGE);
1407                         audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1408                                          msg_type == AUDIT_ADD_RULE ?
1409                                                 "add_rule" : "remove_rule",
1410                                          audit_enabled);
1411                         audit_log_end(ab);
1412                         return -EPERM;
1413                 }
1414                 err = audit_rule_change(msg_type, seq, data, data_len);
1415                 break;
1416         case AUDIT_LIST_RULES:
1417                 err = audit_list_rules_send(skb, seq);
1418                 break;
1419         case AUDIT_TRIM:
1420                 audit_trim_trees();
1421                 audit_log_common_recv_msg(audit_context(), &ab,
1422                                           AUDIT_CONFIG_CHANGE);
1423                 audit_log_format(ab, " op=trim res=1");
1424                 audit_log_end(ab);
1425                 break;
1426         case AUDIT_MAKE_EQUIV: {
1427                 void *bufp = data;
1428                 u32 sizes[2];
1429                 size_t msglen = data_len;
1430                 char *old, *new;
1431 
1432                 err = -EINVAL;
1433                 if (msglen < 2 * sizeof(u32))
1434                         break;
1435                 memcpy(sizes, bufp, 2 * sizeof(u32));
1436                 bufp += 2 * sizeof(u32);
1437                 msglen -= 2 * sizeof(u32);
1438                 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1439                 if (IS_ERR(old)) {
1440                         err = PTR_ERR(old);
1441                         break;
1442                 }
1443                 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1444                 if (IS_ERR(new)) {
1445                         err = PTR_ERR(new);
1446                         kfree(old);
1447                         break;
1448                 }
1449                 /* OK, here comes... */
1450                 err = audit_tag_tree(old, new);
1451 
1452                 audit_log_common_recv_msg(audit_context(), &ab,
1453                                           AUDIT_CONFIG_CHANGE);
1454                 audit_log_format(ab, " op=make_equiv old=");
1455                 audit_log_untrustedstring(ab, old);
1456                 audit_log_format(ab, " new=");
1457                 audit_log_untrustedstring(ab, new);
1458                 audit_log_format(ab, " res=%d", !err);
1459                 audit_log_end(ab);
1460                 kfree(old);
1461                 kfree(new);
1462                 break;
1463         }
1464         case AUDIT_SIGNAL_INFO:
1465                 len = 0;
1466                 if (audit_sig_sid) {
1467                         err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1468                         if (err)
1469                                 return err;
1470                 }
1471                 sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL);
1472                 if (!sig_data) {
1473                         if (audit_sig_sid)
1474                                 security_release_secctx(ctx, len);
1475                         return -ENOMEM;
1476                 }
1477                 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1478                 sig_data->pid = audit_sig_pid;
1479                 if (audit_sig_sid) {
1480                         memcpy(sig_data->ctx, ctx, len);
1481                         security_release_secctx(ctx, len);
1482                 }
1483                 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1484                                  sig_data, struct_size(sig_data, ctx, len));
1485                 kfree(sig_data);
1486                 break;
1487         case AUDIT_TTY_GET: {
1488                 struct audit_tty_status s;
1489                 unsigned int t;
1490 
1491                 t = READ_ONCE(current->signal->audit_tty);
1492                 s.enabled = t & AUDIT_TTY_ENABLE;
1493                 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1494 
1495                 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1496                 break;
1497         }
1498         case AUDIT_TTY_SET: {
1499                 struct audit_tty_status s, old;
1500                 struct audit_buffer     *ab;
1501                 unsigned int t;
1502 
1503                 memset(&s, 0, sizeof(s));
1504                 /* guard against past and future API changes */
1505                 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1506                 /* check if new data is valid */
1507                 if ((s.enabled != 0 && s.enabled != 1) ||
1508                     (s.log_passwd != 0 && s.log_passwd != 1))
1509                         err = -EINVAL;
1510 
1511                 if (err)
1512                         t = READ_ONCE(current->signal->audit_tty);
1513                 else {
1514                         t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1515                         t = xchg(&current->signal->audit_tty, t);
1516                 }
1517                 old.enabled = t & AUDIT_TTY_ENABLE;
1518                 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1519 
1520                 audit_log_common_recv_msg(audit_context(), &ab,
1521                                           AUDIT_CONFIG_CHANGE);
1522                 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1523                                  " old-log_passwd=%d new-log_passwd=%d res=%d",
1524                                  old.enabled, s.enabled, old.log_passwd,
1525                                  s.log_passwd, !err);
1526                 audit_log_end(ab);
1527                 break;
1528         }
1529         default:
1530                 err = -EINVAL;
1531                 break;
1532         }
1533 
1534         return err < 0 ? err : 0;
1535 }
1536 
1537 /**
1538  * audit_receive - receive messages from a netlink control socket
1539  * @skb: the message buffer
1540  *
1541  * Parse the provided skb and deal with any messages that may be present,
1542  * malformed skbs are discarded.
1543  */
1544 static void audit_receive(struct sk_buff  *skb)
1545 {
1546         struct nlmsghdr *nlh;
1547         /*
1548          * len MUST be signed for nlmsg_next to be able to dec it below 0
1549          * if the nlmsg_len was not aligned
1550          */
1551         int len;
1552         int err;
1553 
1554         nlh = nlmsg_hdr(skb);
1555         len = skb->len;
1556 
1557         audit_ctl_lock();
1558         while (nlmsg_ok(nlh, len)) {
1559                 err = audit_receive_msg(skb, nlh);
1560                 /* if err or if this message says it wants a response */
1561                 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1562                         netlink_ack(skb, nlh, err, NULL);
1563 
1564                 nlh = nlmsg_next(nlh, &len);
1565         }
1566         audit_ctl_unlock();
1567 
1568         /* can't block with the ctrl lock, so penalize the sender now */
1569         if (audit_backlog_limit &&
1570             (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1571                 DECLARE_WAITQUEUE(wait, current);
1572 
1573                 /* wake kauditd to try and flush the queue */
1574                 wake_up_interruptible(&kauditd_wait);
1575 
1576                 add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1577                 set_current_state(TASK_UNINTERRUPTIBLE);
1578                 schedule_timeout(audit_backlog_wait_time);
1579                 remove_wait_queue(&audit_backlog_wait, &wait);
1580         }
1581 }
1582 
1583 /* Log information about who is connecting to the audit multicast socket */
1584 static void audit_log_multicast(int group, const char *op, int err)
1585 {
1586         const struct cred *cred;
1587         struct tty_struct *tty;
1588         char comm[sizeof(current->comm)];
1589         struct audit_buffer *ab;
1590 
1591         if (!audit_enabled)
1592                 return;
1593 
1594         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1595         if (!ab)
1596                 return;
1597 
1598         cred = current_cred();
1599         tty = audit_get_tty();
1600         audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1601                          task_pid_nr(current),
1602                          from_kuid(&init_user_ns, cred->uid),
1603                          from_kuid(&init_user_ns, audit_get_loginuid(current)),
1604                          tty ? tty_name(tty) : "(none)",
1605                          audit_get_sessionid(current));
1606         audit_put_tty(tty);
1607         audit_log_task_context(ab); /* subj= */
1608         audit_log_format(ab, " comm=");
1609         audit_log_untrustedstring(ab, get_task_comm(comm, current));
1610         audit_log_d_path_exe(ab, current->mm); /* exe= */
1611         audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1612         audit_log_end(ab);
1613 }
1614 
1615 /* Run custom bind function on netlink socket group connect or bind requests. */
1616 static int audit_multicast_bind(struct net *net, int group)
1617 {
1618         int err = 0;
1619 
1620         if (!capable(CAP_AUDIT_READ))
1621                 err = -EPERM;
1622         audit_log_multicast(group, "connect", err);
1623         return err;
1624 }
1625 
1626 static void audit_multicast_unbind(struct net *net, int group)
1627 {
1628         audit_log_multicast(group, "disconnect", 0);
1629 }
1630 
1631 static int __net_init audit_net_init(struct net *net)
1632 {
1633         struct netlink_kernel_cfg cfg = {
1634                 .input  = audit_receive,
1635                 .bind   = audit_multicast_bind,
1636                 .unbind = audit_multicast_unbind,
1637                 .flags  = NL_CFG_F_NONROOT_RECV,
1638                 .groups = AUDIT_NLGRP_MAX,
1639         };
1640 
1641         struct audit_net *aunet = net_generic(net, audit_net_id);
1642 
1643         aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1644         if (aunet->sk == NULL) {
1645                 audit_panic("cannot initialize netlink socket in namespace");
1646                 return -ENOMEM;
1647         }
1648         /* limit the timeout in case auditd is blocked/stopped */
1649         aunet->sk->sk_sndtimeo = HZ / 10;
1650 
1651         return 0;
1652 }
1653 
1654 static void __net_exit audit_net_exit(struct net *net)
1655 {
1656         struct audit_net *aunet = net_generic(net, audit_net_id);
1657 
1658         /* NOTE: you would think that we would want to check the auditd
1659          * connection and potentially reset it here if it lives in this
1660          * namespace, but since the auditd connection tracking struct holds a
1661          * reference to this namespace (see auditd_set()) we are only ever
1662          * going to get here after that connection has been released */
1663 
1664         netlink_kernel_release(aunet->sk);
1665 }
1666 
1667 static struct pernet_operations audit_net_ops __net_initdata = {
1668         .init = audit_net_init,
1669         .exit = audit_net_exit,
1670         .id = &audit_net_id,
1671         .size = sizeof(struct audit_net),
1672 };
1673 
1674 /* Initialize audit support at boot time. */
1675 static int __init audit_init(void)
1676 {
1677         int i;
1678 
1679         if (audit_initialized == AUDIT_DISABLED)
1680                 return 0;
1681 
1682         audit_buffer_cache = kmem_cache_create("audit_buffer",
1683                                                sizeof(struct audit_buffer),
1684                                                0, SLAB_PANIC, NULL);
1685 
1686         skb_queue_head_init(&audit_queue);
1687         skb_queue_head_init(&audit_retry_queue);
1688         skb_queue_head_init(&audit_hold_queue);
1689 
1690         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1691                 INIT_LIST_HEAD(&audit_inode_hash[i]);
1692 
1693         mutex_init(&audit_cmd_mutex.lock);
1694         audit_cmd_mutex.owner = NULL;
1695 
1696         pr_info("initializing netlink subsys (%s)\n",
1697                 audit_default ? "enabled" : "disabled");
1698         register_pernet_subsys(&audit_net_ops);
1699 
1700         audit_initialized = AUDIT_INITIALIZED;
1701 
1702         kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1703         if (IS_ERR(kauditd_task)) {
1704                 int err = PTR_ERR(kauditd_task);
1705                 panic("audit: failed to start the kauditd thread (%d)\n", err);
1706         }
1707 
1708         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1709                 "state=initialized audit_enabled=%u res=1",
1710                  audit_enabled);
1711 
1712         return 0;
1713 }
1714 postcore_initcall(audit_init);
1715 
1716 /*
1717  * Process kernel command-line parameter at boot time.
1718  * audit={0|off} or audit={1|on}.
1719  */
1720 static int __init audit_enable(char *str)
1721 {
1722         if (!strcasecmp(str, "off") || !strcmp(str, ""))
1723                 audit_default = AUDIT_OFF;
1724         else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1725                 audit_default = AUDIT_ON;
1726         else {
1727                 pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1728                 audit_default = AUDIT_ON;
1729         }
1730 
1731         if (audit_default == AUDIT_OFF)
1732                 audit_initialized = AUDIT_DISABLED;
1733         if (audit_set_enabled(audit_default))
1734                 pr_err("audit: error setting audit state (%d)\n",
1735                        audit_default);
1736 
1737         pr_info("%s\n", audit_default ?
1738                 "enabled (after initialization)" : "disabled (until reboot)");
1739 
1740         return 1;
1741 }
1742 __setup("audit=", audit_enable);
1743 
1744 /* Process kernel command-line parameter at boot time.
1745  * audit_backlog_limit=<n> */
1746 static int __init audit_backlog_limit_set(char *str)
1747 {
1748         u32 audit_backlog_limit_arg;
1749 
1750         pr_info("audit_backlog_limit: ");
1751         if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1752                 pr_cont("using default of %u, unable to parse %s\n",
1753                         audit_backlog_limit, str);
1754                 return 1;
1755         }
1756 
1757         audit_backlog_limit = audit_backlog_limit_arg;
1758         pr_cont("%d\n", audit_backlog_limit);
1759 
1760         return 1;
1761 }
1762 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1763 
1764 static void audit_buffer_free(struct audit_buffer *ab)
1765 {
1766         if (!ab)
1767                 return;
1768 
1769         kfree_skb(ab->skb);
1770         kmem_cache_free(audit_buffer_cache, ab);
1771 }
1772 
1773 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1774                                                gfp_t gfp_mask, int type)
1775 {
1776         struct audit_buffer *ab;
1777 
1778         ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1779         if (!ab)
1780                 return NULL;
1781 
1782         ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1783         if (!ab->skb)
1784                 goto err;
1785         if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1786                 goto err;
1787 
1788         ab->ctx = ctx;
1789         ab->gfp_mask = gfp_mask;
1790 
1791         return ab;
1792 
1793 err:
1794         audit_buffer_free(ab);
1795         return NULL;
1796 }
1797 
1798 /**
1799  * audit_serial - compute a serial number for the audit record
1800  *
1801  * Compute a serial number for the audit record.  Audit records are
1802  * written to user-space as soon as they are generated, so a complete
1803  * audit record may be written in several pieces.  The timestamp of the
1804  * record and this serial number are used by the user-space tools to
1805  * determine which pieces belong to the same audit record.  The
1806  * (timestamp,serial) tuple is unique for each syscall and is live from
1807  * syscall entry to syscall exit.
1808  *
1809  * NOTE: Another possibility is to store the formatted records off the
1810  * audit context (for those records that have a context), and emit them
1811  * all at syscall exit.  However, this could delay the reporting of
1812  * significant errors until syscall exit (or never, if the system
1813  * halts).
1814  */
1815 unsigned int audit_serial(void)
1816 {
1817         static atomic_t serial = ATOMIC_INIT(0);
1818 
1819         return atomic_inc_return(&serial);
1820 }
1821 
1822 static inline void audit_get_stamp(struct audit_context *ctx,
1823                                    struct timespec64 *t, unsigned int *serial)
1824 {
1825         if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1826                 ktime_get_coarse_real_ts64(t);
1827                 *serial = audit_serial();
1828         }
1829 }
1830 
1831 /**
1832  * audit_log_start - obtain an audit buffer
1833  * @ctx: audit_context (may be NULL)
1834  * @gfp_mask: type of allocation
1835  * @type: audit message type
1836  *
1837  * Returns audit_buffer pointer on success or NULL on error.
1838  *
1839  * Obtain an audit buffer.  This routine does locking to obtain the
1840  * audit buffer, but then no locking is required for calls to
1841  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1842  * syscall, then the syscall is marked as auditable and an audit record
1843  * will be written at syscall exit.  If there is no associated task, then
1844  * task context (ctx) should be NULL.
1845  */
1846 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1847                                      int type)
1848 {
1849         struct audit_buffer *ab;
1850         struct timespec64 t;
1851         unsigned int serial;
1852 
1853         if (audit_initialized != AUDIT_INITIALIZED)
1854                 return NULL;
1855 
1856         if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1857                 return NULL;
1858 
1859         /* NOTE: don't ever fail/sleep on these two conditions:
1860          * 1. auditd generated record - since we need auditd to drain the
1861          *    queue; also, when we are checking for auditd, compare PIDs using
1862          *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1863          *    using a PID anchored in the caller's namespace
1864          * 2. generator holding the audit_cmd_mutex - we don't want to block
1865          *    while holding the mutex, although we do penalize the sender
1866          *    later in audit_receive() when it is safe to block
1867          */
1868         if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1869                 long stime = audit_backlog_wait_time;
1870 
1871                 while (audit_backlog_limit &&
1872                        (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1873                         /* wake kauditd to try and flush the queue */
1874                         wake_up_interruptible(&kauditd_wait);
1875 
1876                         /* sleep if we are allowed and we haven't exhausted our
1877                          * backlog wait limit */
1878                         if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1879                                 long rtime = stime;
1880 
1881                                 DECLARE_WAITQUEUE(wait, current);
1882 
1883                                 add_wait_queue_exclusive(&audit_backlog_wait,
1884                                                          &wait);
1885                                 set_current_state(TASK_UNINTERRUPTIBLE);
1886                                 stime = schedule_timeout(rtime);
1887                                 atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1888                                 remove_wait_queue(&audit_backlog_wait, &wait);
1889                         } else {
1890                                 if (audit_rate_check() && printk_ratelimit())
1891                                         pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1892                                                 skb_queue_len(&audit_queue),
1893                                                 audit_backlog_limit);
1894                                 audit_log_lost("backlog limit exceeded");
1895                                 return NULL;
1896                         }
1897                 }
1898         }
1899 
1900         ab = audit_buffer_alloc(ctx, gfp_mask, type);
1901         if (!ab) {
1902                 audit_log_lost("out of memory in audit_log_start");
1903                 return NULL;
1904         }
1905 
1906         audit_get_stamp(ab->ctx, &t, &serial);
1907         /* cancel dummy context to enable supporting records */
1908         if (ctx)
1909                 ctx->dummy = 0;
1910         audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1911                          (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1912 
1913         return ab;
1914 }
1915 
1916 /**
1917  * audit_expand - expand skb in the audit buffer
1918  * @ab: audit_buffer
1919  * @extra: space to add at tail of the skb
1920  *
1921  * Returns 0 (no space) on failed expansion, or available space if
1922  * successful.
1923  */
1924 static inline int audit_expand(struct audit_buffer *ab, int extra)
1925 {
1926         struct sk_buff *skb = ab->skb;
1927         int oldtail = skb_tailroom(skb);
1928         int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1929         int newtail = skb_tailroom(skb);
1930 
1931         if (ret < 0) {
1932                 audit_log_lost("out of memory in audit_expand");
1933                 return 0;
1934         }
1935 
1936         skb->truesize += newtail - oldtail;
1937         return newtail;
1938 }
1939 
1940 /*
1941  * Format an audit message into the audit buffer.  If there isn't enough
1942  * room in the audit buffer, more room will be allocated and vsnprint
1943  * will be called a second time.  Currently, we assume that a printk
1944  * can't format message larger than 1024 bytes, so we don't either.
1945  */
1946 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1947                               va_list args)
1948 {
1949         int len, avail;
1950         struct sk_buff *skb;
1951         va_list args2;
1952 
1953         if (!ab)
1954                 return;
1955 
1956         BUG_ON(!ab->skb);
1957         skb = ab->skb;
1958         avail = skb_tailroom(skb);
1959         if (avail == 0) {
1960                 avail = audit_expand(ab, AUDIT_BUFSIZ);
1961                 if (!avail)
1962                         goto out;
1963         }
1964         va_copy(args2, args);
1965         len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1966         if (len >= avail) {
1967                 /* The printk buffer is 1024 bytes long, so if we get
1968                  * here and AUDIT_BUFSIZ is at least 1024, then we can
1969                  * log everything that printk could have logged. */
1970                 avail = audit_expand(ab,
1971                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1972                 if (!avail)
1973                         goto out_va_end;
1974                 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1975         }
1976         if (len > 0)
1977                 skb_put(skb, len);
1978 out_va_end:
1979         va_end(args2);
1980 out:
1981         return;
1982 }
1983 
1984 /**
1985  * audit_log_format - format a message into the audit buffer.
1986  * @ab: audit_buffer
1987  * @fmt: format string
1988  * @...: optional parameters matching @fmt string
1989  *
1990  * All the work is done in audit_log_vformat.
1991  */
1992 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1993 {
1994         va_list args;
1995 
1996         if (!ab)
1997                 return;
1998         va_start(args, fmt);
1999         audit_log_vformat(ab, fmt, args);
2000         va_end(args);
2001 }
2002 
2003 /**
2004  * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
2005  * @ab: the audit_buffer
2006  * @buf: buffer to convert to hex
2007  * @len: length of @buf to be converted
2008  *
2009  * No return value; failure to expand is silently ignored.
2010  *
2011  * This function will take the passed buf and convert it into a string of
2012  * ascii hex digits. The new string is placed onto the skb.
2013  */
2014 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
2015                 size_t len)
2016 {
2017         int i, avail, new_len;
2018         unsigned char *ptr;
2019         struct sk_buff *skb;
2020 
2021         if (!ab)
2022                 return;
2023 
2024         BUG_ON(!ab->skb);
2025         skb = ab->skb;
2026         avail = skb_tailroom(skb);
2027         new_len = len<<1;
2028         if (new_len >= avail) {
2029                 /* Round the buffer request up to the next multiple */
2030                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2031                 avail = audit_expand(ab, new_len);
2032                 if (!avail)
2033                         return;
2034         }
2035 
2036         ptr = skb_tail_pointer(skb);
2037         for (i = 0; i < len; i++)
2038                 ptr = hex_byte_pack_upper(ptr, buf[i]);
2039         *ptr = 0;
2040         skb_put(skb, len << 1); /* new string is twice the old string */
2041 }
2042 
2043 /*
2044  * Format a string of no more than slen characters into the audit buffer,
2045  * enclosed in quote marks.
2046  */
2047 void audit_log_n_string(struct audit_buffer *ab, const char *string,
2048                         size_t slen)
2049 {
2050         int avail, new_len;
2051         unsigned char *ptr;
2052         struct sk_buff *skb;
2053 
2054         if (!ab)
2055                 return;
2056 
2057         BUG_ON(!ab->skb);
2058         skb = ab->skb;
2059         avail = skb_tailroom(skb);
2060         new_len = slen + 3;     /* enclosing quotes + null terminator */
2061         if (new_len > avail) {
2062                 avail = audit_expand(ab, new_len);
2063                 if (!avail)
2064                         return;
2065         }
2066         ptr = skb_tail_pointer(skb);
2067         *ptr++ = '"';
2068         memcpy(ptr, string, slen);
2069         ptr += slen;
2070         *ptr++ = '"';
2071         *ptr = 0;
2072         skb_put(skb, slen + 2); /* don't include null terminator */
2073 }
2074 
2075 /**
2076  * audit_string_contains_control - does a string need to be logged in hex
2077  * @string: string to be checked
2078  * @len: max length of the string to check
2079  */
2080 bool audit_string_contains_control(const char *string, size_t len)
2081 {
2082         const unsigned char *p;
2083         for (p = string; p < (const unsigned char *)string + len; p++) {
2084                 if (*p == '"' || *p < 0x21 || *p > 0x7e)
2085                         return true;
2086         }
2087         return false;
2088 }
2089 
2090 /**
2091  * audit_log_n_untrustedstring - log a string that may contain random characters
2092  * @ab: audit_buffer
2093  * @len: length of string (not including trailing null)
2094  * @string: string to be logged
2095  *
2096  * This code will escape a string that is passed to it if the string
2097  * contains a control character, unprintable character, double quote mark,
2098  * or a space. Unescaped strings will start and end with a double quote mark.
2099  * Strings that are escaped are printed in hex (2 digits per char).
2100  *
2101  * The caller specifies the number of characters in the string to log, which may
2102  * or may not be the entire string.
2103  */
2104 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2105                                  size_t len)
2106 {
2107         if (audit_string_contains_control(string, len))
2108                 audit_log_n_hex(ab, string, len);
2109         else
2110                 audit_log_n_string(ab, string, len);
2111 }
2112 
2113 /**
2114  * audit_log_untrustedstring - log a string that may contain random characters
2115  * @ab: audit_buffer
2116  * @string: string to be logged
2117  *
2118  * Same as audit_log_n_untrustedstring(), except that strlen is used to
2119  * determine string length.
2120  */
2121 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2122 {
2123         audit_log_n_untrustedstring(ab, string, strlen(string));
2124 }
2125 
2126 /* This is a helper-function to print the escaped d_path */
2127 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2128                       const struct path *path)
2129 {
2130         char *p, *pathname;
2131 
2132         if (prefix)
2133                 audit_log_format(ab, "%s", prefix);
2134 
2135         /* We will allow 11 spaces for ' (deleted)' to be appended */
2136         pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2137         if (!pathname) {
2138                 audit_log_format(ab, "\"<no_memory>\"");
2139                 return;
2140         }
2141         p = d_path(path, pathname, PATH_MAX+11);
2142         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2143                 /* FIXME: can we save some information here? */
2144                 audit_log_format(ab, "\"<too_long>\"");
2145         } else
2146                 audit_log_untrustedstring(ab, p);
2147         kfree(pathname);
2148 }
2149 
2150 void audit_log_session_info(struct audit_buffer *ab)
2151 {
2152         unsigned int sessionid = audit_get_sessionid(current);
2153         uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2154 
2155         audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2156 }
2157 
2158 void audit_log_key(struct audit_buffer *ab, char *key)
2159 {
2160         audit_log_format(ab, " key=");
2161         if (key)
2162                 audit_log_untrustedstring(ab, key);
2163         else
2164                 audit_log_format(ab, "(null)");
2165 }
2166 
2167 int audit_log_task_context(struct audit_buffer *ab)
2168 {
2169         char *ctx = NULL;
2170         unsigned len;
2171         int error;
2172         u32 sid;
2173 
2174         security_current_getsecid_subj(&sid);
2175         if (!sid)
2176                 return 0;
2177 
2178         error = security_secid_to_secctx(sid, &ctx, &len);
2179         if (error) {
2180                 if (error != -EINVAL)
2181                         goto error_path;
2182                 return 0;
2183         }
2184 
2185         audit_log_format(ab, " subj=%s", ctx);
2186         security_release_secctx(ctx, len);
2187         return 0;
2188 
2189 error_path:
2190         audit_panic("error in audit_log_task_context");
2191         return error;
2192 }
2193 EXPORT_SYMBOL(audit_log_task_context);
2194 
2195 void audit_log_d_path_exe(struct audit_buffer *ab,
2196                           struct mm_struct *mm)
2197 {
2198         struct file *exe_file;
2199 
2200         if (!mm)
2201                 goto out_null;
2202 
2203         exe_file = get_mm_exe_file(mm);
2204         if (!exe_file)
2205                 goto out_null;
2206 
2207         audit_log_d_path(ab, " exe=", &exe_file->f_path);
2208         fput(exe_file);
2209         return;
2210 out_null:
2211         audit_log_format(ab, " exe=(null)");
2212 }
2213 
2214 struct tty_struct *audit_get_tty(void)
2215 {
2216         struct tty_struct *tty = NULL;
2217         unsigned long flags;
2218 
2219         spin_lock_irqsave(&current->sighand->siglock, flags);
2220         if (current->signal)
2221                 tty = tty_kref_get(current->signal->tty);
2222         spin_unlock_irqrestore(&current->sighand->siglock, flags);
2223         return tty;
2224 }
2225 
2226 void audit_put_tty(struct tty_struct *tty)
2227 {
2228         tty_kref_put(tty);
2229 }
2230 
2231 void audit_log_task_info(struct audit_buffer *ab)
2232 {
2233         const struct cred *cred;
2234         char comm[sizeof(current->comm)];
2235         struct tty_struct *tty;
2236 
2237         if (!ab)
2238                 return;
2239 
2240         cred = current_cred();
2241         tty = audit_get_tty();
2242         audit_log_format(ab,
2243                          " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2244                          " euid=%u suid=%u fsuid=%u"
2245                          " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2246                          task_ppid_nr(current),
2247                          task_tgid_nr(current),
2248                          from_kuid(&init_user_ns, audit_get_loginuid(current)),
2249                          from_kuid(&init_user_ns, cred->uid),
2250                          from_kgid(&init_user_ns, cred->gid),
2251                          from_kuid(&init_user_ns, cred->euid),
2252                          from_kuid(&init_user_ns, cred->suid),
2253                          from_kuid(&init_user_ns, cred->fsuid),
2254                          from_kgid(&init_user_ns, cred->egid),
2255                          from_kgid(&init_user_ns, cred->sgid),
2256                          from_kgid(&init_user_ns, cred->fsgid),
2257                          tty ? tty_name(tty) : "(none)",
2258                          audit_get_sessionid(current));
2259         audit_put_tty(tty);
2260         audit_log_format(ab, " comm=");
2261         audit_log_untrustedstring(ab, get_task_comm(comm, current));
2262         audit_log_d_path_exe(ab, current->mm);
2263         audit_log_task_context(ab);
2264 }
2265 EXPORT_SYMBOL(audit_log_task_info);
2266 
2267 /**
2268  * audit_log_path_denied - report a path restriction denial
2269  * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2270  * @operation: specific operation name
2271  */
2272 void audit_log_path_denied(int type, const char *operation)
2273 {
2274         struct audit_buffer *ab;
2275 
2276         if (!audit_enabled || audit_dummy_context())
2277                 return;
2278 
2279         /* Generate log with subject, operation, outcome. */
2280         ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2281         if (!ab)
2282                 return;
2283         audit_log_format(ab, "op=%s", operation);
2284         audit_log_task_info(ab);
2285         audit_log_format(ab, " res=0");
2286         audit_log_end(ab);
2287 }
2288 
2289 /* global counter which is incremented every time something logs in */
2290 static atomic_t session_id = ATOMIC_INIT(0);
2291 
2292 static int audit_set_loginuid_perm(kuid_t loginuid)
2293 {
2294         /* if we are unset, we don't need privs */
2295         if (!audit_loginuid_set(current))
2296                 return 0;
2297         /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2298         if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2299                 return -EPERM;
2300         /* it is set, you need permission */
2301         if (!capable(CAP_AUDIT_CONTROL))
2302                 return -EPERM;
2303         /* reject if this is not an unset and we don't allow that */
2304         if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2305                                  && uid_valid(loginuid))
2306                 return -EPERM;
2307         return 0;
2308 }
2309 
2310 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2311                                    unsigned int oldsessionid,
2312                                    unsigned int sessionid, int rc)
2313 {
2314         struct audit_buffer *ab;
2315         uid_t uid, oldloginuid, loginuid;
2316         struct tty_struct *tty;
2317 
2318         if (!audit_enabled)
2319                 return;
2320 
2321         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2322         if (!ab)
2323                 return;
2324 
2325         uid = from_kuid(&init_user_ns, task_uid(current));
2326         oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2327         loginuid = from_kuid(&init_user_ns, kloginuid);
2328         tty = audit_get_tty();
2329 
2330         audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2331         audit_log_task_context(ab);
2332         audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2333                          oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2334                          oldsessionid, sessionid, !rc);
2335         audit_put_tty(tty);
2336         audit_log_end(ab);
2337 }
2338 
2339 /**
2340  * audit_set_loginuid - set current task's loginuid
2341  * @loginuid: loginuid value
2342  *
2343  * Returns 0.
2344  *
2345  * Called (set) from fs/proc/base.c::proc_loginuid_write().
2346  */
2347 int audit_set_loginuid(kuid_t loginuid)
2348 {
2349         unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2350         kuid_t oldloginuid;
2351         int rc;
2352 
2353         oldloginuid = audit_get_loginuid(current);
2354         oldsessionid = audit_get_sessionid(current);
2355 
2356         rc = audit_set_loginuid_perm(loginuid);
2357         if (rc)
2358                 goto out;
2359 
2360         /* are we setting or clearing? */
2361         if (uid_valid(loginuid)) {
2362                 sessionid = (unsigned int)atomic_inc_return(&session_id);
2363                 if (unlikely(sessionid == AUDIT_SID_UNSET))
2364                         sessionid = (unsigned int)atomic_inc_return(&session_id);
2365         }
2366 
2367         current->sessionid = sessionid;
2368         current->loginuid = loginuid;
2369 out:
2370         audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2371         return rc;
2372 }
2373 
2374 /**
2375  * audit_signal_info - record signal info for shutting down audit subsystem
2376  * @sig: signal value
2377  * @t: task being signaled
2378  *
2379  * If the audit subsystem is being terminated, record the task (pid)
2380  * and uid that is doing that.
2381  */
2382 int audit_signal_info(int sig, struct task_struct *t)
2383 {
2384         kuid_t uid = current_uid(), auid;
2385 
2386         if (auditd_test_task(t) &&
2387             (sig == SIGTERM || sig == SIGHUP ||
2388              sig == SIGUSR1 || sig == SIGUSR2)) {
2389                 audit_sig_pid = task_tgid_nr(current);
2390                 auid = audit_get_loginuid(current);
2391                 if (uid_valid(auid))
2392                         audit_sig_uid = auid;
2393                 else
2394                         audit_sig_uid = uid;
2395                 security_current_getsecid_subj(&audit_sig_sid);
2396         }
2397 
2398         return audit_signal_info_syscall(t);
2399 }
2400 
2401 /**
2402  * audit_log_end - end one audit record
2403  * @ab: the audit_buffer
2404  *
2405  * We can not do a netlink send inside an irq context because it blocks (last
2406  * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2407  * queue and a kthread is scheduled to remove them from the queue outside the
2408  * irq context.  May be called in any context.
2409  */
2410 void audit_log_end(struct audit_buffer *ab)
2411 {
2412         struct sk_buff *skb;
2413         struct nlmsghdr *nlh;
2414 
2415         if (!ab)
2416                 return;
2417 
2418         if (audit_rate_check()) {
2419                 skb = ab->skb;
2420                 ab->skb = NULL;
2421 
2422                 /* setup the netlink header, see the comments in
2423                  * kauditd_send_multicast_skb() for length quirks */
2424                 nlh = nlmsg_hdr(skb);
2425                 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2426 
2427                 /* queue the netlink packet and poke the kauditd thread */
2428                 skb_queue_tail(&audit_queue, skb);
2429                 wake_up_interruptible(&kauditd_wait);
2430         } else
2431                 audit_log_lost("rate limit exceeded");
2432 
2433         audit_buffer_free(ab);
2434 }
2435 
2436 /**
2437  * audit_log - Log an audit record
2438  * @ctx: audit context
2439  * @gfp_mask: type of allocation
2440  * @type: audit message type
2441  * @fmt: format string to use
2442  * @...: variable parameters matching the format string
2443  *
2444  * This is a convenience function that calls audit_log_start,
2445  * audit_log_vformat, and audit_log_end.  It may be called
2446  * in any context.
2447  */
2448 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2449                const char *fmt, ...)
2450 {
2451         struct audit_buffer *ab;
2452         va_list args;
2453 
2454         ab = audit_log_start(ctx, gfp_mask, type);
2455         if (ab) {
2456                 va_start(args, fmt);
2457                 audit_log_vformat(ab, fmt, args);
2458                 va_end(args);
2459                 audit_log_end(ab);
2460         }
2461 }
2462 
2463 EXPORT_SYMBOL(audit_log_start);
2464 EXPORT_SYMBOL(audit_log_end);
2465 EXPORT_SYMBOL(audit_log_format);
2466 EXPORT_SYMBOL(audit_log);
2467 

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