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
6 * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
9 * Written by Rickard E. (Rik) Faith <faith@redhat.com>
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
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
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.
28 * Audit userspace, documentation, tests, and bug/issue trackers:
29 * https://github.com/linux-audit
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34 #include <linux/file.h>
35 #include <linux/init.h>
36 #include <linux/types.h>
37 #include <linux/atomic.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>
51 #include <linux/audit.h>
54 #include <net/netlink.h>
55 #include <linux/skbuff.h>
56 #ifdef CONFIG_SECURITY
57 #include <linux/security.h>
59 #include <linux/freezer.h>
60 #include <linux/pid_namespace.h>
61 #include <net/netns/generic.h>
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;
72 u32 audit_enabled = AUDIT_OFF;
73 bool audit_ever_enabled = !!AUDIT_OFF;
75 EXPORT_SYMBOL_GPL(audit_enabled);
77 /* Default state when kernel boots without any parameters. */
78 static u32 audit_default = AUDIT_OFF;
80 /* If auditing cannot proceed, audit_failure selects what happens. */
81 static u32 audit_failure = AUDIT_FAIL_PRINTK;
83 /* private audit network namespace index */
84 static unsigned int audit_net_id;
87 * struct audit_net - audit private network namespace data
88 * @sk: communication socket
95 * struct auditd_connection - kernel/auditd connection state
97 * @portid: netlink portid
98 * @net: the associated network namespace
102 * This struct is RCU protected; you must either hold the RCU lock for reading
103 * or the associated spinlock for writing.
105 struct auditd_connection {
111 static struct auditd_connection __rcu *auditd_conn;
112 static DEFINE_SPINLOCK(auditd_conn_lock);
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;
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;
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;
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
137 static atomic_t audit_lost = ATOMIC_INIT(0);
139 /* Monotonically increasing sum of time the kernel has spent
140 * waiting while the backlog limit is exceeded.
142 static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
144 /* Hash for inode-based rules */
145 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
147 static struct kmem_cache *audit_buffer_cache;
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;
156 /* queue servicing thread */
157 static struct task_struct *kauditd_task;
158 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
160 /* waitqueue for callers who are blocked on the audit backlog */
161 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
163 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
168 static char *audit_feature_names[2] = {
169 "only_unset_loginuid",
170 "loginuid_immutable",
174 * struct audit_ctl_mutex - serialize requests from userspace
175 * @lock: the mutex used for locking
176 * @owner: the task which owns the lock
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.
184 static struct audit_ctl_mutex {
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
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 */
212 * auditd_test_task - Check to see if a given task is an audit daemon
213 * @task: the task to check
216 * Return 1 if the task is a registered audit daemon, 0 otherwise.
218 int auditd_test_task(struct task_struct *task)
221 struct auditd_connection *ac;
224 ac = rcu_dereference(auditd_conn);
225 rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
232 * audit_ctl_lock - Take the audit control lock
234 void audit_ctl_lock(void)
236 mutex_lock(&audit_cmd_mutex.lock);
237 audit_cmd_mutex.owner = current;
241 * audit_ctl_unlock - Drop the audit control lock
243 void audit_ctl_unlock(void)
245 audit_cmd_mutex.owner = NULL;
246 mutex_unlock(&audit_cmd_mutex.lock);
250 * audit_ctl_owner_current - Test to see if the current task owns the lock
253 * Return true if the current task owns the audit control lock, false if it
254 * doesn't own the lock.
256 static bool audit_ctl_owner_current(void)
258 return (current == audit_cmd_mutex.owner);
262 * auditd_pid_vnr - Return the auditd PID relative to the namespace
265 * Returns the PID in relation to the namespace, 0 on failure.
267 static pid_t auditd_pid_vnr(void)
270 const struct auditd_connection *ac;
273 ac = rcu_dereference(auditd_conn);
277 pid = pid_vnr(ac->pid);
284 * audit_get_sk - Return the audit socket for the given network namespace
285 * @net: the destination network namespace
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.
291 static struct sock *audit_get_sk(const struct net *net)
293 struct audit_net *aunet;
298 aunet = net_generic(net, audit_net_id);
302 void audit_panic(const char *message)
304 switch (audit_failure) {
305 case AUDIT_FAIL_SILENT:
307 case AUDIT_FAIL_PRINTK:
308 if (printk_ratelimit())
309 pr_err("%s\n", message);
311 case AUDIT_FAIL_PANIC:
312 panic("audit: %s\n", message);
317 static inline int audit_rate_check(void)
319 static unsigned long last_check = 0;
320 static int messages = 0;
321 static DEFINE_SPINLOCK(lock);
324 unsigned long elapsed;
327 if (!audit_rate_limit) return 1;
329 spin_lock_irqsave(&lock, flags);
330 if (++messages < audit_rate_limit) {
334 elapsed = now - last_check;
341 spin_unlock_irqrestore(&lock, flags);
347 * audit_log_lost - conditionally log lost audit message event
348 * @message: the message stating reason for lost audit message
350 * Emit at least 1 message per second, even if audit_rate_check is
352 * Always increment the lost messages counter.
354 void audit_log_lost(const char *message)
356 static unsigned long last_msg = 0;
357 static DEFINE_SPINLOCK(lock);
362 atomic_inc(&audit_lost);
364 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
367 spin_lock_irqsave(&lock, flags);
369 if (now - last_msg > HZ) {
373 spin_unlock_irqrestore(&lock, flags);
377 if (printk_ratelimit())
378 pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
379 atomic_read(&audit_lost),
381 audit_backlog_limit);
382 audit_panic(message);
386 static int audit_log_config_change(char *function_name, u32 new, u32 old,
389 struct audit_buffer *ab;
392 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
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);
399 allow_changes = 0; /* Something weird, deny request */
400 audit_log_format(ab, " res=%d", allow_changes);
405 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
407 int allow_changes, rc = 0;
408 u32 old = *to_change;
410 /* check if we are locked */
411 if (audit_enabled == AUDIT_LOCKED)
416 if (audit_enabled != AUDIT_OFF) {
417 rc = audit_log_config_change(function_name, new, old, allow_changes);
422 /* If we are allowed, make the change */
423 if (allow_changes == 1)
425 /* Not allowed, update reason */
431 static int audit_set_rate_limit(u32 limit)
433 return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
436 static int audit_set_backlog_limit(u32 limit)
438 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
441 static int audit_set_backlog_wait_time(u32 timeout)
443 return audit_do_config_change("audit_backlog_wait_time",
444 &audit_backlog_wait_time, timeout);
447 static int audit_set_enabled(u32 state)
450 if (state > AUDIT_LOCKED)
453 rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
455 audit_ever_enabled |= !!state;
460 static int audit_set_failure(u32 state)
462 if (state != AUDIT_FAIL_SILENT
463 && state != AUDIT_FAIL_PRINTK
464 && state != AUDIT_FAIL_PANIC)
467 return audit_do_config_change("audit_failure", &audit_failure, state);
471 * auditd_conn_free - RCU helper to release an auditd connection struct
475 * Drop any references inside the auditd connection tracking struct and free
478 static void auditd_conn_free(struct rcu_head *rcu)
480 struct auditd_connection *ac;
482 ac = container_of(rcu, struct auditd_connection, rcu);
489 * auditd_set - Set/Reset the auditd connection state
491 * @portid: auditd netlink portid
492 * @net: auditd network namespace pointer
493 * @skb: the netlink command from the audit daemon
494 * @ack: netlink ack flag, cleared if ack'd here
497 * This function will obtain and drop network namespace references as
498 * necessary. Returns zero on success, negative values on failure.
500 static int auditd_set(struct pid *pid, u32 portid, struct net *net,
501 struct sk_buff *skb, bool *ack)
504 struct auditd_connection *ac_old, *ac_new;
505 struct nlmsghdr *nlh;
510 ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
513 ac_new->pid = get_pid(pid);
514 ac_new->portid = portid;
515 ac_new->net = get_net(net);
517 /* send the ack now to avoid a race with the queue backlog */
519 nlh = nlmsg_hdr(skb);
520 netlink_ack(skb, nlh, 0, NULL);
524 spin_lock_irqsave(&auditd_conn_lock, flags);
525 ac_old = rcu_dereference_protected(auditd_conn,
526 lockdep_is_held(&auditd_conn_lock));
527 rcu_assign_pointer(auditd_conn, ac_new);
528 spin_unlock_irqrestore(&auditd_conn_lock, flags);
531 call_rcu(&ac_old->rcu, auditd_conn_free);
537 * kauditd_print_skb - Print the audit record to the ring buffer
540 * Whatever the reason, this packet may not make it to the auditd connection
541 * so write it via printk so the information isn't completely lost.
543 static void kauditd_printk_skb(struct sk_buff *skb)
545 struct nlmsghdr *nlh = nlmsg_hdr(skb);
546 char *data = nlmsg_data(nlh);
548 if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
549 pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
553 * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
555 * @error: error code (unused)
558 * This should only be used by the kauditd_thread when it fails to flush the
561 static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error)
563 /* put the record back in the queue */
564 skb_queue_tail(&audit_hold_queue, skb);
568 * kauditd_hold_skb - Queue an audit record, waiting for auditd
573 * Queue the audit record, waiting for an instance of auditd. When this
574 * function is called we haven't given up yet on sending the record, but things
575 * are not looking good. The first thing we want to do is try to write the
576 * record via printk and then see if we want to try and hold on to the record
577 * and queue it, if we have room. If we want to hold on to the record, but we
578 * don't have room, record a record lost message.
580 static void kauditd_hold_skb(struct sk_buff *skb, int error)
582 /* at this point it is uncertain if we will ever send this to auditd so
583 * try to send the message via printk before we go any further */
584 kauditd_printk_skb(skb);
586 /* can we just silently drop the message? */
590 /* the hold queue is only for when the daemon goes away completely,
591 * not -EAGAIN failures; if we are in a -EAGAIN state requeue the
592 * record on the retry queue unless it's full, in which case drop it
594 if (error == -EAGAIN) {
595 if (!audit_backlog_limit ||
596 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
597 skb_queue_tail(&audit_retry_queue, skb);
600 audit_log_lost("kauditd retry queue overflow");
604 /* if we have room in the hold queue, queue the message */
605 if (!audit_backlog_limit ||
606 skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
607 skb_queue_tail(&audit_hold_queue, skb);
611 /* we have no other options - drop the message */
612 audit_log_lost("kauditd hold queue overflow");
618 * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
620 * @error: error code (unused)
623 * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
624 * but for some reason we are having problems sending it audit records so
625 * queue the given record and attempt to resend.
627 static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
629 if (!audit_backlog_limit ||
630 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
631 skb_queue_tail(&audit_retry_queue, skb);
635 /* we have to drop the record, send it via printk as a last effort */
636 kauditd_printk_skb(skb);
637 audit_log_lost("kauditd retry queue overflow");
642 * auditd_reset - Disconnect the auditd connection
643 * @ac: auditd connection state
646 * Break the auditd/kauditd connection and move all the queued records into the
647 * hold queue in case auditd reconnects. It is important to note that the @ac
648 * pointer should never be dereferenced inside this function as it may be NULL
649 * or invalid, you can only compare the memory address! If @ac is NULL then
650 * the connection will always be reset.
652 static void auditd_reset(const struct auditd_connection *ac)
656 struct auditd_connection *ac_old;
658 /* if it isn't already broken, break the connection */
659 spin_lock_irqsave(&auditd_conn_lock, flags);
660 ac_old = rcu_dereference_protected(auditd_conn,
661 lockdep_is_held(&auditd_conn_lock));
662 if (ac && ac != ac_old) {
663 /* someone already registered a new auditd connection */
664 spin_unlock_irqrestore(&auditd_conn_lock, flags);
667 rcu_assign_pointer(auditd_conn, NULL);
668 spin_unlock_irqrestore(&auditd_conn_lock, flags);
671 call_rcu(&ac_old->rcu, auditd_conn_free);
673 /* flush the retry queue to the hold queue, but don't touch the main
674 * queue since we need to process that normally for multicast */
675 while ((skb = skb_dequeue(&audit_retry_queue)))
676 kauditd_hold_skb(skb, -ECONNREFUSED);
680 * auditd_send_unicast_skb - Send a record via unicast to auditd
684 * Send a skb to the audit daemon, returns positive/zero values on success and
685 * negative values on failure; in all cases the skb will be consumed by this
686 * function. If the send results in -ECONNREFUSED the connection with auditd
687 * will be reset. This function may sleep so callers should not hold any locks
688 * where this would cause a problem.
690 static int auditd_send_unicast_skb(struct sk_buff *skb)
696 struct auditd_connection *ac;
698 /* NOTE: we can't call netlink_unicast while in the RCU section so
699 * take a reference to the network namespace and grab local
700 * copies of the namespace, the sock, and the portid; the
701 * namespace and sock aren't going to go away while we hold a
702 * reference and if the portid does become invalid after the RCU
703 * section netlink_unicast() should safely return an error */
706 ac = rcu_dereference(auditd_conn);
713 net = get_net(ac->net);
714 sk = audit_get_sk(net);
718 rc = netlink_unicast(sk, skb, portid, 0);
726 if (ac && rc == -ECONNREFUSED)
732 * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
733 * @sk: the sending sock
734 * @portid: the netlink destination
735 * @queue: the skb queue to process
736 * @retry_limit: limit on number of netlink unicast failures
737 * @skb_hook: per-skb hook for additional processing
738 * @err_hook: hook called if the skb fails the netlink unicast send
741 * Run through the given queue and attempt to send the audit records to auditd,
742 * returns zero on success, negative values on failure. It is up to the caller
743 * to ensure that the @sk is valid for the duration of this function.
746 static int kauditd_send_queue(struct sock *sk, u32 portid,
747 struct sk_buff_head *queue,
748 unsigned int retry_limit,
749 void (*skb_hook)(struct sk_buff *skb),
750 void (*err_hook)(struct sk_buff *skb, int error))
753 struct sk_buff *skb = NULL;
754 struct sk_buff *skb_tail;
755 unsigned int failed = 0;
757 /* NOTE: kauditd_thread takes care of all our locking, we just use
758 * the netlink info passed to us (e.g. sk and portid) */
760 skb_tail = skb_peek_tail(queue);
761 while ((skb != skb_tail) && (skb = skb_dequeue(queue))) {
762 /* call the skb_hook for each skb we touch */
766 /* can we send to anyone via unicast? */
769 (*err_hook)(skb, -ECONNREFUSED);
774 /* grab an extra skb reference in case of error */
776 rc = netlink_unicast(sk, skb, portid, 0);
778 /* send failed - try a few times unless fatal error */
779 if (++failed >= retry_limit ||
780 rc == -ECONNREFUSED || rc == -EPERM) {
783 (*err_hook)(skb, rc);
786 /* continue to drain the queue */
791 /* skb sent - drop the extra reference and continue */
797 return (rc >= 0 ? 0 : rc);
801 * kauditd_send_multicast_skb - Send a record to any multicast listeners
805 * Write a multicast message to anyone listening in the initial network
806 * namespace. This function doesn't consume an skb as might be expected since
807 * it has to copy it anyways.
809 static void kauditd_send_multicast_skb(struct sk_buff *skb)
811 struct sk_buff *copy;
812 struct sock *sock = audit_get_sk(&init_net);
813 struct nlmsghdr *nlh;
815 /* NOTE: we are not taking an additional reference for init_net since
816 * we don't have to worry about it going away */
818 if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
822 * The seemingly wasteful skb_copy() rather than bumping the refcount
823 * using skb_get() is necessary because non-standard mods are made to
824 * the skb by the original kaudit unicast socket send routine. The
825 * existing auditd daemon assumes this breakage. Fixing this would
826 * require co-ordinating a change in the established protocol between
827 * the kaudit kernel subsystem and the auditd userspace code. There is
828 * no reason for new multicast clients to continue with this
831 copy = skb_copy(skb, GFP_KERNEL);
834 nlh = nlmsg_hdr(copy);
835 nlh->nlmsg_len = skb->len;
837 nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
841 * kauditd_thread - Worker thread to send audit records to userspace
844 static int kauditd_thread(void *dummy)
848 struct net *net = NULL;
849 struct sock *sk = NULL;
850 struct auditd_connection *ac;
852 #define UNICAST_RETRIES 5
855 while (!kthread_should_stop()) {
856 /* NOTE: see the lock comments in auditd_send_unicast_skb() */
858 ac = rcu_dereference(auditd_conn);
863 net = get_net(ac->net);
864 sk = audit_get_sk(net);
868 /* attempt to flush the hold queue */
869 rc = kauditd_send_queue(sk, portid,
870 &audit_hold_queue, UNICAST_RETRIES,
871 NULL, kauditd_rehold_skb);
878 /* attempt to flush the retry queue */
879 rc = kauditd_send_queue(sk, portid,
880 &audit_retry_queue, UNICAST_RETRIES,
881 NULL, kauditd_hold_skb);
889 /* process the main queue - do the multicast send and attempt
890 * unicast, dump failed record sends to the retry queue; if
891 * sk == NULL due to previous failures we will just do the
892 * multicast send and move the record to the hold queue */
893 rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
894 kauditd_send_multicast_skb,
896 kauditd_retry_skb : kauditd_hold_skb));
901 /* drop our netns reference, no auditd sends past this line */
907 /* we have processed all the queues so wake everyone */
908 wake_up(&audit_backlog_wait);
910 /* NOTE: we want to wake up if there is anything on the queue,
911 * regardless of if an auditd is connected, as we need to
912 * do the multicast send and rotate records from the
913 * main queue to the retry/hold queues */
914 wait_event_freezable(kauditd_wait,
915 (skb_queue_len(&audit_queue) ? 1 : 0));
921 int audit_send_list_thread(void *_dest)
923 struct audit_netlink_list *dest = _dest;
925 struct sock *sk = audit_get_sk(dest->net);
927 /* wait for parent to finish and send an ACK */
931 while ((skb = __skb_dequeue(&dest->q)) != NULL)
932 netlink_unicast(sk, skb, dest->portid, 0);
940 struct sk_buff *audit_make_reply(int seq, int type, int done,
941 int multi, const void *payload, int size)
944 struct nlmsghdr *nlh;
946 int flags = multi ? NLM_F_MULTI : 0;
947 int t = done ? NLMSG_DONE : type;
949 skb = nlmsg_new(size, GFP_KERNEL);
953 nlh = nlmsg_put(skb, 0, seq, t, size, flags);
956 data = nlmsg_data(nlh);
957 memcpy(data, payload, size);
965 static void audit_free_reply(struct audit_reply *reply)
970 kfree_skb(reply->skb);
976 static int audit_send_reply_thread(void *arg)
978 struct audit_reply *reply = (struct audit_reply *)arg;
983 /* Ignore failure. It'll only happen if the sender goes away,
984 because our timeout is set to infinite. */
985 netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
987 audit_free_reply(reply);
992 * audit_send_reply - send an audit reply message via netlink
993 * @request_skb: skb of request we are replying to (used to target the reply)
994 * @seq: sequence number
995 * @type: audit message type
996 * @done: done (last) flag
997 * @multi: multi-part message flag
998 * @payload: payload data
999 * @size: payload size
1001 * Allocates a skb, builds the netlink message, and sends it to the port id.
1003 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
1004 int multi, const void *payload, int size)
1006 struct task_struct *tsk;
1007 struct audit_reply *reply;
1009 reply = kzalloc(sizeof(*reply), GFP_KERNEL);
1013 reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
1016 reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
1017 reply->portid = NETLINK_CB(request_skb).portid;
1019 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
1026 audit_free_reply(reply);
1030 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
1033 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1037 /* Only support initial user namespace for now. */
1039 * We return ECONNREFUSED because it tricks userspace into thinking
1040 * that audit was not configured into the kernel. Lots of users
1041 * configure their PAM stack (because that's what the distro does)
1042 * to reject login if unable to send messages to audit. If we return
1043 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1044 * configured in and will let login proceed. If we return EPERM
1045 * userspace will reject all logins. This should be removed when we
1046 * support non init namespaces!!
1048 if (current_user_ns() != &init_user_ns)
1049 return -ECONNREFUSED;
1058 case AUDIT_GET_FEATURE:
1059 case AUDIT_SET_FEATURE:
1060 case AUDIT_LIST_RULES:
1061 case AUDIT_ADD_RULE:
1062 case AUDIT_DEL_RULE:
1063 case AUDIT_SIGNAL_INFO:
1067 case AUDIT_MAKE_EQUIV:
1068 /* Only support auditd and auditctl in initial pid namespace
1070 if (task_active_pid_ns(current) != &init_pid_ns)
1073 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1077 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1078 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1079 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1082 default: /* bad msg */
1089 static void audit_log_common_recv_msg(struct audit_context *context,
1090 struct audit_buffer **ab, u16 msg_type)
1092 uid_t uid = from_kuid(&init_user_ns, current_uid());
1093 pid_t pid = task_tgid_nr(current);
1095 if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1100 *ab = audit_log_start(context, GFP_KERNEL, msg_type);
1103 audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1104 audit_log_session_info(*ab);
1105 audit_log_task_context(*ab);
1108 static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1111 audit_log_common_recv_msg(NULL, ab, msg_type);
1114 int is_audit_feature_set(int i)
1116 return af.features & AUDIT_FEATURE_TO_MASK(i);
1120 static int audit_get_feature(struct sk_buff *skb)
1124 seq = nlmsg_hdr(skb)->nlmsg_seq;
1126 audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1131 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1132 u32 old_lock, u32 new_lock, int res)
1134 struct audit_buffer *ab;
1136 if (audit_enabled == AUDIT_OFF)
1139 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1142 audit_log_task_info(ab);
1143 audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1144 audit_feature_names[which], !!old_feature, !!new_feature,
1145 !!old_lock, !!new_lock, res);
1149 static int audit_set_feature(struct audit_features *uaf)
1153 BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1155 /* if there is ever a version 2 we should handle that here */
1157 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1158 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1159 u32 old_feature, new_feature, old_lock, new_lock;
1161 /* if we are not changing this feature, move along */
1162 if (!(feature & uaf->mask))
1165 old_feature = af.features & feature;
1166 new_feature = uaf->features & feature;
1167 new_lock = (uaf->lock | af.lock) & feature;
1168 old_lock = af.lock & feature;
1170 /* are we changing a locked feature? */
1171 if (old_lock && (new_feature != old_feature)) {
1172 audit_log_feature_change(i, old_feature, new_feature,
1173 old_lock, new_lock, 0);
1177 /* nothing invalid, do the changes */
1178 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1179 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1180 u32 old_feature, new_feature, old_lock, new_lock;
1182 /* if we are not changing this feature, move along */
1183 if (!(feature & uaf->mask))
1186 old_feature = af.features & feature;
1187 new_feature = uaf->features & feature;
1188 old_lock = af.lock & feature;
1189 new_lock = (uaf->lock | af.lock) & feature;
1191 if (new_feature != old_feature)
1192 audit_log_feature_change(i, old_feature, new_feature,
1193 old_lock, new_lock, 1);
1196 af.features |= feature;
1198 af.features &= ~feature;
1199 af.lock |= new_lock;
1205 static int audit_replace(struct pid *pid)
1208 struct sk_buff *skb;
1210 pvnr = pid_vnr(pid);
1211 skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1214 return auditd_send_unicast_skb(skb);
1217 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
1224 struct audit_buffer *ab;
1225 u16 msg_type = nlh->nlmsg_type;
1226 struct audit_sig_info *sig_data;
1230 err = audit_netlink_ok(skb, msg_type);
1234 seq = nlh->nlmsg_seq;
1235 data = nlmsg_data(nlh);
1236 data_len = nlmsg_len(nlh);
1240 struct audit_status s;
1241 memset(&s, 0, sizeof(s));
1242 s.enabled = audit_enabled;
1243 s.failure = audit_failure;
1244 /* NOTE: use pid_vnr() so the PID is relative to the current
1246 s.pid = auditd_pid_vnr();
1247 s.rate_limit = audit_rate_limit;
1248 s.backlog_limit = audit_backlog_limit;
1249 s.lost = atomic_read(&audit_lost);
1250 s.backlog = skb_queue_len(&audit_queue);
1251 s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL;
1252 s.backlog_wait_time = audit_backlog_wait_time;
1253 s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1254 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1258 struct audit_status s;
1259 memset(&s, 0, sizeof(s));
1260 /* guard against past and future API changes */
1261 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1262 if (s.mask & AUDIT_STATUS_ENABLED) {
1263 err = audit_set_enabled(s.enabled);
1267 if (s.mask & AUDIT_STATUS_FAILURE) {
1268 err = audit_set_failure(s.failure);
1272 if (s.mask & AUDIT_STATUS_PID) {
1273 /* NOTE: we are using the vnr PID functions below
1274 * because the s.pid value is relative to the
1275 * namespace of the caller; at present this
1276 * doesn't matter much since you can really only
1277 * run auditd from the initial pid namespace, but
1278 * something to keep in mind if this changes */
1279 pid_t new_pid = s.pid;
1281 struct pid *req_pid = task_tgid(current);
1283 /* Sanity check - PID values must match. Setting
1284 * pid to 0 is how auditd ends auditing. */
1285 if (new_pid && (new_pid != pid_vnr(req_pid)))
1288 /* test the auditd connection */
1289 audit_replace(req_pid);
1291 auditd_pid = auditd_pid_vnr();
1293 /* replacing a healthy auditd is not allowed */
1295 audit_log_config_change("audit_pid",
1296 new_pid, auditd_pid, 0);
1299 /* only current auditd can unregister itself */
1300 if (pid_vnr(req_pid) != auditd_pid) {
1301 audit_log_config_change("audit_pid",
1302 new_pid, auditd_pid, 0);
1308 /* register a new auditd connection */
1309 err = auditd_set(req_pid,
1310 NETLINK_CB(skb).portid,
1311 sock_net(NETLINK_CB(skb).sk),
1313 if (audit_enabled != AUDIT_OFF)
1314 audit_log_config_change("audit_pid",
1321 /* try to process any backlog */
1322 wake_up_interruptible(&kauditd_wait);
1324 if (audit_enabled != AUDIT_OFF)
1325 audit_log_config_change("audit_pid",
1329 /* unregister the auditd connection */
1333 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1334 err = audit_set_rate_limit(s.rate_limit);
1338 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1339 err = audit_set_backlog_limit(s.backlog_limit);
1343 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1344 if (sizeof(s) > (size_t)nlh->nlmsg_len)
1346 if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1348 err = audit_set_backlog_wait_time(s.backlog_wait_time);
1352 if (s.mask == AUDIT_STATUS_LOST) {
1353 u32 lost = atomic_xchg(&audit_lost, 0);
1355 audit_log_config_change("lost", 0, lost, 1);
1358 if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1359 u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1361 audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1366 case AUDIT_GET_FEATURE:
1367 err = audit_get_feature(skb);
1371 case AUDIT_SET_FEATURE:
1372 if (data_len < sizeof(struct audit_features))
1374 err = audit_set_feature(data);
1379 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1380 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1381 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1383 /* exit early if there isn't at least one character to print */
1387 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1388 if (err == 1) { /* match or error */
1392 if (msg_type == AUDIT_USER_TTY) {
1393 err = tty_audit_push();
1397 audit_log_user_recv_msg(&ab, msg_type);
1398 if (msg_type != AUDIT_USER_TTY) {
1399 /* ensure NULL termination */
1400 str[data_len - 1] = '\0';
1401 audit_log_format(ab, " msg='%.*s'",
1402 AUDIT_MESSAGE_TEXT_MAX,
1405 audit_log_format(ab, " data=");
1406 if (data_len > 0 && str[data_len - 1] == '\0')
1408 audit_log_n_untrustedstring(ab, str, data_len);
1413 case AUDIT_ADD_RULE:
1414 case AUDIT_DEL_RULE:
1415 if (data_len < sizeof(struct audit_rule_data))
1417 if (audit_enabled == AUDIT_LOCKED) {
1418 audit_log_common_recv_msg(audit_context(), &ab,
1419 AUDIT_CONFIG_CHANGE);
1420 audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1421 msg_type == AUDIT_ADD_RULE ?
1422 "add_rule" : "remove_rule",
1427 err = audit_rule_change(msg_type, seq, data, data_len);
1429 case AUDIT_LIST_RULES:
1430 err = audit_list_rules_send(skb, seq);
1434 audit_log_common_recv_msg(audit_context(), &ab,
1435 AUDIT_CONFIG_CHANGE);
1436 audit_log_format(ab, " op=trim res=1");
1439 case AUDIT_MAKE_EQUIV: {
1442 size_t msglen = data_len;
1446 if (msglen < 2 * sizeof(u32))
1448 memcpy(sizes, bufp, 2 * sizeof(u32));
1449 bufp += 2 * sizeof(u32);
1450 msglen -= 2 * sizeof(u32);
1451 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1456 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1462 /* OK, here comes... */
1463 err = audit_tag_tree(old, new);
1465 audit_log_common_recv_msg(audit_context(), &ab,
1466 AUDIT_CONFIG_CHANGE);
1467 audit_log_format(ab, " op=make_equiv old=");
1468 audit_log_untrustedstring(ab, old);
1469 audit_log_format(ab, " new=");
1470 audit_log_untrustedstring(ab, new);
1471 audit_log_format(ab, " res=%d", !err);
1477 case AUDIT_SIGNAL_INFO:
1479 if (audit_sig_sid) {
1480 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1484 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1487 security_release_secctx(ctx, len);
1490 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1491 sig_data->pid = audit_sig_pid;
1492 if (audit_sig_sid) {
1493 memcpy(sig_data->ctx, ctx, len);
1494 security_release_secctx(ctx, len);
1496 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1497 sig_data, sizeof(*sig_data) + len);
1500 case AUDIT_TTY_GET: {
1501 struct audit_tty_status s;
1504 t = READ_ONCE(current->signal->audit_tty);
1505 s.enabled = t & AUDIT_TTY_ENABLE;
1506 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1508 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1511 case AUDIT_TTY_SET: {
1512 struct audit_tty_status s, old;
1513 struct audit_buffer *ab;
1516 memset(&s, 0, sizeof(s));
1517 /* guard against past and future API changes */
1518 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1519 /* check if new data is valid */
1520 if ((s.enabled != 0 && s.enabled != 1) ||
1521 (s.log_passwd != 0 && s.log_passwd != 1))
1525 t = READ_ONCE(current->signal->audit_tty);
1527 t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1528 t = xchg(¤t->signal->audit_tty, t);
1530 old.enabled = t & AUDIT_TTY_ENABLE;
1531 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1533 audit_log_common_recv_msg(audit_context(), &ab,
1534 AUDIT_CONFIG_CHANGE);
1535 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1536 " old-log_passwd=%d new-log_passwd=%d res=%d",
1537 old.enabled, s.enabled, old.log_passwd,
1538 s.log_passwd, !err);
1547 return err < 0 ? err : 0;
1551 * audit_receive - receive messages from a netlink control socket
1552 * @skb: the message buffer
1554 * Parse the provided skb and deal with any messages that may be present,
1555 * malformed skbs are discarded.
1557 static void audit_receive(struct sk_buff *skb)
1559 struct nlmsghdr *nlh;
1562 * len MUST be signed for nlmsg_next to be able to dec it below 0
1563 * if the nlmsg_len was not aligned
1568 nlh = nlmsg_hdr(skb);
1572 while (nlmsg_ok(nlh, len)) {
1573 ack = nlh->nlmsg_flags & NLM_F_ACK;
1574 err = audit_receive_msg(skb, nlh, &ack);
1576 /* send an ack if the user asked for one and audit_receive_msg
1577 * didn't already do it, or if there was an error. */
1579 netlink_ack(skb, nlh, err, NULL);
1581 nlh = nlmsg_next(nlh, &len);
1585 /* can't block with the ctrl lock, so penalize the sender now */
1586 if (audit_backlog_limit &&
1587 (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1588 DECLARE_WAITQUEUE(wait, current);
1590 /* wake kauditd to try and flush the queue */
1591 wake_up_interruptible(&kauditd_wait);
1593 add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1594 set_current_state(TASK_UNINTERRUPTIBLE);
1595 schedule_timeout(audit_backlog_wait_time);
1596 remove_wait_queue(&audit_backlog_wait, &wait);
1600 /* Log information about who is connecting to the audit multicast socket */
1601 static void audit_log_multicast(int group, const char *op, int err)
1603 const struct cred *cred;
1604 struct tty_struct *tty;
1605 char comm[sizeof(current->comm)];
1606 struct audit_buffer *ab;
1611 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1615 cred = current_cred();
1616 tty = audit_get_tty();
1617 audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1618 task_pid_nr(current),
1619 from_kuid(&init_user_ns, cred->uid),
1620 from_kuid(&init_user_ns, audit_get_loginuid(current)),
1621 tty ? tty_name(tty) : "(none)",
1622 audit_get_sessionid(current));
1624 audit_log_task_context(ab); /* subj= */
1625 audit_log_format(ab, " comm=");
1626 audit_log_untrustedstring(ab, get_task_comm(comm, current));
1627 audit_log_d_path_exe(ab, current->mm); /* exe= */
1628 audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1632 /* Run custom bind function on netlink socket group connect or bind requests. */
1633 static int audit_multicast_bind(struct net *net, int group)
1637 if (!capable(CAP_AUDIT_READ))
1639 audit_log_multicast(group, "connect", err);
1643 static void audit_multicast_unbind(struct net *net, int group)
1645 audit_log_multicast(group, "disconnect", 0);
1648 static int __net_init audit_net_init(struct net *net)
1650 struct netlink_kernel_cfg cfg = {
1651 .input = audit_receive,
1652 .bind = audit_multicast_bind,
1653 .unbind = audit_multicast_unbind,
1654 .flags = NL_CFG_F_NONROOT_RECV,
1655 .groups = AUDIT_NLGRP_MAX,
1658 struct audit_net *aunet = net_generic(net, audit_net_id);
1660 aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1661 if (aunet->sk == NULL) {
1662 audit_panic("cannot initialize netlink socket in namespace");
1665 /* limit the timeout in case auditd is blocked/stopped */
1666 aunet->sk->sk_sndtimeo = HZ / 10;
1671 static void __net_exit audit_net_exit(struct net *net)
1673 struct audit_net *aunet = net_generic(net, audit_net_id);
1675 /* NOTE: you would think that we would want to check the auditd
1676 * connection and potentially reset it here if it lives in this
1677 * namespace, but since the auditd connection tracking struct holds a
1678 * reference to this namespace (see auditd_set()) we are only ever
1679 * going to get here after that connection has been released */
1681 netlink_kernel_release(aunet->sk);
1684 static struct pernet_operations audit_net_ops __net_initdata = {
1685 .init = audit_net_init,
1686 .exit = audit_net_exit,
1687 .id = &audit_net_id,
1688 .size = sizeof(struct audit_net),
1691 /* Initialize audit support at boot time. */
1692 static int __init audit_init(void)
1696 if (audit_initialized == AUDIT_DISABLED)
1699 audit_buffer_cache = kmem_cache_create("audit_buffer",
1700 sizeof(struct audit_buffer),
1701 0, SLAB_PANIC, NULL);
1703 skb_queue_head_init(&audit_queue);
1704 skb_queue_head_init(&audit_retry_queue);
1705 skb_queue_head_init(&audit_hold_queue);
1707 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1708 INIT_LIST_HEAD(&audit_inode_hash[i]);
1710 mutex_init(&audit_cmd_mutex.lock);
1711 audit_cmd_mutex.owner = NULL;
1713 pr_info("initializing netlink subsys (%s)\n",
1714 audit_default ? "enabled" : "disabled");
1715 register_pernet_subsys(&audit_net_ops);
1717 audit_initialized = AUDIT_INITIALIZED;
1719 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1720 if (IS_ERR(kauditd_task)) {
1721 int err = PTR_ERR(kauditd_task);
1722 panic("audit: failed to start the kauditd thread (%d)\n", err);
1725 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1726 "state=initialized audit_enabled=%u res=1",
1731 postcore_initcall(audit_init);
1734 * Process kernel command-line parameter at boot time.
1735 * audit={0|off} or audit={1|on}.
1737 static int __init audit_enable(char *str)
1739 if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1740 audit_default = AUDIT_OFF;
1741 else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1742 audit_default = AUDIT_ON;
1744 pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1745 audit_default = AUDIT_ON;
1748 if (audit_default == AUDIT_OFF)
1749 audit_initialized = AUDIT_DISABLED;
1750 if (audit_set_enabled(audit_default))
1751 pr_err("audit: error setting audit state (%d)\n",
1754 pr_info("%s\n", audit_default ?
1755 "enabled (after initialization)" : "disabled (until reboot)");
1759 __setup("audit=", audit_enable);
1761 /* Process kernel command-line parameter at boot time.
1762 * audit_backlog_limit=<n> */
1763 static int __init audit_backlog_limit_set(char *str)
1765 u32 audit_backlog_limit_arg;
1767 pr_info("audit_backlog_limit: ");
1768 if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1769 pr_cont("using default of %u, unable to parse %s\n",
1770 audit_backlog_limit, str);
1774 audit_backlog_limit = audit_backlog_limit_arg;
1775 pr_cont("%d\n", audit_backlog_limit);
1779 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1781 static void audit_buffer_free(struct audit_buffer *ab)
1787 kmem_cache_free(audit_buffer_cache, ab);
1790 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1791 gfp_t gfp_mask, int type)
1793 struct audit_buffer *ab;
1795 ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1799 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1802 if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1806 ab->gfp_mask = gfp_mask;
1811 audit_buffer_free(ab);
1816 * audit_serial - compute a serial number for the audit record
1818 * Compute a serial number for the audit record. Audit records are
1819 * written to user-space as soon as they are generated, so a complete
1820 * audit record may be written in several pieces. The timestamp of the
1821 * record and this serial number are used by the user-space tools to
1822 * determine which pieces belong to the same audit record. The
1823 * (timestamp,serial) tuple is unique for each syscall and is live from
1824 * syscall entry to syscall exit.
1826 * NOTE: Another possibility is to store the formatted records off the
1827 * audit context (for those records that have a context), and emit them
1828 * all at syscall exit. However, this could delay the reporting of
1829 * significant errors until syscall exit (or never, if the system
1832 unsigned int audit_serial(void)
1834 static atomic_t serial = ATOMIC_INIT(0);
1836 return atomic_add_return(1, &serial);
1839 static inline void audit_get_stamp(struct audit_context *ctx,
1840 struct timespec64 *t, unsigned int *serial)
1842 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1843 ktime_get_coarse_real_ts64(t);
1844 *serial = audit_serial();
1849 * audit_log_start - obtain an audit buffer
1850 * @ctx: audit_context (may be NULL)
1851 * @gfp_mask: type of allocation
1852 * @type: audit message type
1854 * Returns audit_buffer pointer on success or NULL on error.
1856 * Obtain an audit buffer. This routine does locking to obtain the
1857 * audit buffer, but then no locking is required for calls to
1858 * audit_log_*format. If the task (ctx) is a task that is currently in a
1859 * syscall, then the syscall is marked as auditable and an audit record
1860 * will be written at syscall exit. If there is no associated task, then
1861 * task context (ctx) should be NULL.
1863 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1866 struct audit_buffer *ab;
1867 struct timespec64 t;
1868 unsigned int serial;
1870 if (audit_initialized != AUDIT_INITIALIZED)
1873 if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1876 /* NOTE: don't ever fail/sleep on these two conditions:
1877 * 1. auditd generated record - since we need auditd to drain the
1878 * queue; also, when we are checking for auditd, compare PIDs using
1879 * task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1880 * using a PID anchored in the caller's namespace
1881 * 2. generator holding the audit_cmd_mutex - we don't want to block
1882 * while holding the mutex, although we do penalize the sender
1883 * later in audit_receive() when it is safe to block
1885 if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1886 long stime = audit_backlog_wait_time;
1888 while (audit_backlog_limit &&
1889 (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1890 /* wake kauditd to try and flush the queue */
1891 wake_up_interruptible(&kauditd_wait);
1893 /* sleep if we are allowed and we haven't exhausted our
1894 * backlog wait limit */
1895 if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1898 DECLARE_WAITQUEUE(wait, current);
1900 add_wait_queue_exclusive(&audit_backlog_wait,
1902 set_current_state(TASK_UNINTERRUPTIBLE);
1903 stime = schedule_timeout(rtime);
1904 atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1905 remove_wait_queue(&audit_backlog_wait, &wait);
1907 if (audit_rate_check() && printk_ratelimit())
1908 pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1909 skb_queue_len(&audit_queue),
1910 audit_backlog_limit);
1911 audit_log_lost("backlog limit exceeded");
1917 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1919 audit_log_lost("out of memory in audit_log_start");
1923 audit_get_stamp(ab->ctx, &t, &serial);
1924 audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1925 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1931 * audit_expand - expand skb in the audit buffer
1933 * @extra: space to add at tail of the skb
1935 * Returns 0 (no space) on failed expansion, or available space if
1938 static inline int audit_expand(struct audit_buffer *ab, int extra)
1940 struct sk_buff *skb = ab->skb;
1941 int oldtail = skb_tailroom(skb);
1942 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1943 int newtail = skb_tailroom(skb);
1946 audit_log_lost("out of memory in audit_expand");
1950 skb->truesize += newtail - oldtail;
1955 * Format an audit message into the audit buffer. If there isn't enough
1956 * room in the audit buffer, more room will be allocated and vsnprint
1957 * will be called a second time. Currently, we assume that a printk
1958 * can't format message larger than 1024 bytes, so we don't either.
1960 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1964 struct sk_buff *skb;
1972 avail = skb_tailroom(skb);
1974 avail = audit_expand(ab, AUDIT_BUFSIZ);
1978 va_copy(args2, args);
1979 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1981 /* The printk buffer is 1024 bytes long, so if we get
1982 * here and AUDIT_BUFSIZ is at least 1024, then we can
1983 * log everything that printk could have logged. */
1984 avail = audit_expand(ab,
1985 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1988 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1999 * audit_log_format - format a message into the audit buffer.
2001 * @fmt: format string
2002 * @...: optional parameters matching @fmt string
2004 * All the work is done in audit_log_vformat.
2006 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
2012 va_start(args, fmt);
2013 audit_log_vformat(ab, fmt, args);
2018 * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
2019 * @ab: the audit_buffer
2020 * @buf: buffer to convert to hex
2021 * @len: length of @buf to be converted
2023 * No return value; failure to expand is silently ignored.
2025 * This function will take the passed buf and convert it into a string of
2026 * ascii hex digits. The new string is placed onto the skb.
2028 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
2031 int i, avail, new_len;
2033 struct sk_buff *skb;
2040 avail = skb_tailroom(skb);
2042 if (new_len >= avail) {
2043 /* Round the buffer request up to the next multiple */
2044 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2045 avail = audit_expand(ab, new_len);
2050 ptr = skb_tail_pointer(skb);
2051 for (i = 0; i < len; i++)
2052 ptr = hex_byte_pack_upper(ptr, buf[i]);
2054 skb_put(skb, len << 1); /* new string is twice the old string */
2058 * Format a string of no more than slen characters into the audit buffer,
2059 * enclosed in quote marks.
2061 void audit_log_n_string(struct audit_buffer *ab, const char *string,
2066 struct sk_buff *skb;
2073 avail = skb_tailroom(skb);
2074 new_len = slen + 3; /* enclosing quotes + null terminator */
2075 if (new_len > avail) {
2076 avail = audit_expand(ab, new_len);
2080 ptr = skb_tail_pointer(skb);
2082 memcpy(ptr, string, slen);
2086 skb_put(skb, slen + 2); /* don't include null terminator */
2090 * audit_string_contains_control - does a string need to be logged in hex
2091 * @string: string to be checked
2092 * @len: max length of the string to check
2094 bool audit_string_contains_control(const char *string, size_t len)
2096 const unsigned char *p;
2097 for (p = string; p < (const unsigned char *)string + len; p++) {
2098 if (*p == '"' || *p < 0x21 || *p > 0x7e)
2105 * audit_log_n_untrustedstring - log a string that may contain random characters
2107 * @len: length of string (not including trailing null)
2108 * @string: string to be logged
2110 * This code will escape a string that is passed to it if the string
2111 * contains a control character, unprintable character, double quote mark,
2112 * or a space. Unescaped strings will start and end with a double quote mark.
2113 * Strings that are escaped are printed in hex (2 digits per char).
2115 * The caller specifies the number of characters in the string to log, which may
2116 * or may not be the entire string.
2118 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2121 if (audit_string_contains_control(string, len))
2122 audit_log_n_hex(ab, string, len);
2124 audit_log_n_string(ab, string, len);
2128 * audit_log_untrustedstring - log a string that may contain random characters
2130 * @string: string to be logged
2132 * Same as audit_log_n_untrustedstring(), except that strlen is used to
2133 * determine string length.
2135 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2137 audit_log_n_untrustedstring(ab, string, strlen(string));
2140 /* This is a helper-function to print the escaped d_path */
2141 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2142 const struct path *path)
2147 audit_log_format(ab, "%s", prefix);
2149 /* We will allow 11 spaces for ' (deleted)' to be appended */
2150 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2152 audit_log_format(ab, "\"<no_memory>\"");
2155 p = d_path(path, pathname, PATH_MAX+11);
2156 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2157 /* FIXME: can we save some information here? */
2158 audit_log_format(ab, "\"<too_long>\"");
2160 audit_log_untrustedstring(ab, p);
2164 void audit_log_session_info(struct audit_buffer *ab)
2166 unsigned int sessionid = audit_get_sessionid(current);
2167 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2169 audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2172 void audit_log_key(struct audit_buffer *ab, char *key)
2174 audit_log_format(ab, " key=");
2176 audit_log_untrustedstring(ab, key);
2178 audit_log_format(ab, "(null)");
2181 int audit_log_task_context(struct audit_buffer *ab)
2188 security_task_getsecid(current, &sid);
2192 error = security_secid_to_secctx(sid, &ctx, &len);
2194 if (error != -EINVAL)
2199 audit_log_format(ab, " subj=%s", ctx);
2200 security_release_secctx(ctx, len);
2204 audit_panic("error in audit_log_task_context");
2207 EXPORT_SYMBOL(audit_log_task_context);
2209 void audit_log_d_path_exe(struct audit_buffer *ab,
2210 struct mm_struct *mm)
2212 struct file *exe_file;
2217 exe_file = get_mm_exe_file(mm);
2221 audit_log_d_path(ab, " exe=", &exe_file->f_path);
2225 audit_log_format(ab, " exe=(null)");
2228 struct tty_struct *audit_get_tty(void)
2230 struct tty_struct *tty = NULL;
2231 unsigned long flags;
2233 spin_lock_irqsave(¤t->sighand->siglock, flags);
2234 if (current->signal)
2235 tty = tty_kref_get(current->signal->tty);
2236 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
2240 void audit_put_tty(struct tty_struct *tty)
2245 void audit_log_task_info(struct audit_buffer *ab)
2247 const struct cred *cred;
2248 char comm[sizeof(current->comm)];
2249 struct tty_struct *tty;
2254 cred = current_cred();
2255 tty = audit_get_tty();
2256 audit_log_format(ab,
2257 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2258 " euid=%u suid=%u fsuid=%u"
2259 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2260 task_ppid_nr(current),
2261 task_tgid_nr(current),
2262 from_kuid(&init_user_ns, audit_get_loginuid(current)),
2263 from_kuid(&init_user_ns, cred->uid),
2264 from_kgid(&init_user_ns, cred->gid),
2265 from_kuid(&init_user_ns, cred->euid),
2266 from_kuid(&init_user_ns, cred->suid),
2267 from_kuid(&init_user_ns, cred->fsuid),
2268 from_kgid(&init_user_ns, cred->egid),
2269 from_kgid(&init_user_ns, cred->sgid),
2270 from_kgid(&init_user_ns, cred->fsgid),
2271 tty ? tty_name(tty) : "(none)",
2272 audit_get_sessionid(current));
2274 audit_log_format(ab, " comm=");
2275 audit_log_untrustedstring(ab, get_task_comm(comm, current));
2276 audit_log_d_path_exe(ab, current->mm);
2277 audit_log_task_context(ab);
2279 EXPORT_SYMBOL(audit_log_task_info);
2282 * audit_log_path_denied - report a path restriction denial
2283 * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2284 * @operation: specific operation name
2286 void audit_log_path_denied(int type, const char *operation)
2288 struct audit_buffer *ab;
2290 if (!audit_enabled || audit_dummy_context())
2293 /* Generate log with subject, operation, outcome. */
2294 ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2297 audit_log_format(ab, "op=%s", operation);
2298 audit_log_task_info(ab);
2299 audit_log_format(ab, " res=0");
2303 /* global counter which is incremented every time something logs in */
2304 static atomic_t session_id = ATOMIC_INIT(0);
2306 static int audit_set_loginuid_perm(kuid_t loginuid)
2308 /* if we are unset, we don't need privs */
2309 if (!audit_loginuid_set(current))
2311 /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2312 if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2314 /* it is set, you need permission */
2315 if (!capable(CAP_AUDIT_CONTROL))
2317 /* reject if this is not an unset and we don't allow that */
2318 if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2319 && uid_valid(loginuid))
2324 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2325 unsigned int oldsessionid,
2326 unsigned int sessionid, int rc)
2328 struct audit_buffer *ab;
2329 uid_t uid, oldloginuid, loginuid;
2330 struct tty_struct *tty;
2335 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2339 uid = from_kuid(&init_user_ns, task_uid(current));
2340 oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2341 loginuid = from_kuid(&init_user_ns, kloginuid),
2342 tty = audit_get_tty();
2344 audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2345 audit_log_task_context(ab);
2346 audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2347 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2348 oldsessionid, sessionid, !rc);
2354 * audit_set_loginuid - set current task's loginuid
2355 * @loginuid: loginuid value
2359 * Called (set) from fs/proc/base.c::proc_loginuid_write().
2361 int audit_set_loginuid(kuid_t loginuid)
2363 unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2367 oldloginuid = audit_get_loginuid(current);
2368 oldsessionid = audit_get_sessionid(current);
2370 rc = audit_set_loginuid_perm(loginuid);
2374 /* are we setting or clearing? */
2375 if (uid_valid(loginuid)) {
2376 sessionid = (unsigned int)atomic_inc_return(&session_id);
2377 if (unlikely(sessionid == AUDIT_SID_UNSET))
2378 sessionid = (unsigned int)atomic_inc_return(&session_id);
2381 current->sessionid = sessionid;
2382 current->loginuid = loginuid;
2384 audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2389 * audit_signal_info - record signal info for shutting down audit subsystem
2390 * @sig: signal value
2391 * @t: task being signaled
2393 * If the audit subsystem is being terminated, record the task (pid)
2394 * and uid that is doing that.
2396 int audit_signal_info(int sig, struct task_struct *t)
2398 kuid_t uid = current_uid(), auid;
2400 if (auditd_test_task(t) &&
2401 (sig == SIGTERM || sig == SIGHUP ||
2402 sig == SIGUSR1 || sig == SIGUSR2)) {
2403 audit_sig_pid = task_tgid_nr(current);
2404 auid = audit_get_loginuid(current);
2405 if (uid_valid(auid))
2406 audit_sig_uid = auid;
2408 audit_sig_uid = uid;
2409 security_task_getsecid(current, &audit_sig_sid);
2412 return audit_signal_info_syscall(t);
2416 * audit_log_end - end one audit record
2417 * @ab: the audit_buffer
2419 * We can not do a netlink send inside an irq context because it blocks (last
2420 * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2421 * queue and a tasklet is scheduled to remove them from the queue outside the
2422 * irq context. May be called in any context.
2424 void audit_log_end(struct audit_buffer *ab)
2426 struct sk_buff *skb;
2427 struct nlmsghdr *nlh;
2432 if (audit_rate_check()) {
2436 /* setup the netlink header, see the comments in
2437 * kauditd_send_multicast_skb() for length quirks */
2438 nlh = nlmsg_hdr(skb);
2439 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2441 /* queue the netlink packet and poke the kauditd thread */
2442 skb_queue_tail(&audit_queue, skb);
2443 wake_up_interruptible(&kauditd_wait);
2445 audit_log_lost("rate limit exceeded");
2447 audit_buffer_free(ab);
2451 * audit_log - Log an audit record
2452 * @ctx: audit context
2453 * @gfp_mask: type of allocation
2454 * @type: audit message type
2455 * @fmt: format string to use
2456 * @...: variable parameters matching the format string
2458 * This is a convenience function that calls audit_log_start,
2459 * audit_log_vformat, and audit_log_end. It may be called
2462 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2463 const char *fmt, ...)
2465 struct audit_buffer *ab;
2468 ab = audit_log_start(ctx, gfp_mask, type);
2470 va_start(args, fmt);
2471 audit_log_vformat(ab, fmt, args);
2477 EXPORT_SYMBOL(audit_log_start);
2478 EXPORT_SYMBOL(audit_log_end);
2479 EXPORT_SYMBOL(audit_log_format);
2480 EXPORT_SYMBOL(audit_log);