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 #include <linux/security.h>
57 #include <linux/freezer.h>
58 #include <linux/pid_namespace.h>
59 #include <net/netns/generic.h>
63 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
64 * (Initialization happens after skb_init is called.) */
65 #define AUDIT_DISABLED -1
66 #define AUDIT_UNINITIALIZED 0
67 #define AUDIT_INITIALIZED 1
68 static int audit_initialized = AUDIT_UNINITIALIZED;
70 u32 audit_enabled = AUDIT_OFF;
71 bool audit_ever_enabled = !!AUDIT_OFF;
73 EXPORT_SYMBOL_GPL(audit_enabled);
75 /* Default state when kernel boots without any parameters. */
76 static u32 audit_default = AUDIT_OFF;
78 /* If auditing cannot proceed, audit_failure selects what happens. */
79 static u32 audit_failure = AUDIT_FAIL_PRINTK;
81 /* private audit network namespace index */
82 static unsigned int audit_net_id;
85 * struct audit_net - audit private network namespace data
86 * @sk: communication socket
93 * struct auditd_connection - kernel/auditd connection state
95 * @portid: netlink portid
96 * @net: the associated network namespace
100 * This struct is RCU protected; you must either hold the RCU lock for reading
101 * or the associated spinlock for writing.
103 struct auditd_connection {
109 static struct auditd_connection __rcu *auditd_conn;
110 static DEFINE_SPINLOCK(auditd_conn_lock);
112 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
113 * to that number per second. This prevents DoS attacks, but results in
114 * audit records being dropped. */
115 static u32 audit_rate_limit;
117 /* Number of outstanding audit_buffers allowed.
118 * When set to zero, this means unlimited. */
119 static u32 audit_backlog_limit = 64;
120 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
121 static u32 audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
123 /* The identity of the user shutting down the audit system. */
124 static kuid_t audit_sig_uid = INVALID_UID;
125 static pid_t audit_sig_pid = -1;
126 static u32 audit_sig_sid;
128 /* Records can be lost in several ways:
129 0) [suppressed in audit_alloc]
130 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
131 2) out of memory in audit_log_move [alloc_skb]
132 3) suppressed due to audit_rate_limit
133 4) suppressed due to audit_backlog_limit
135 static atomic_t audit_lost = ATOMIC_INIT(0);
137 /* Monotonically increasing sum of time the kernel has spent
138 * waiting while the backlog limit is exceeded.
140 static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
142 /* Hash for inode-based rules */
143 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
145 static struct kmem_cache *audit_buffer_cache;
147 /* queue msgs to send via kauditd_task */
148 static struct sk_buff_head audit_queue;
149 /* queue msgs due to temporary unicast send problems */
150 static struct sk_buff_head audit_retry_queue;
151 /* queue msgs waiting for new auditd connection */
152 static struct sk_buff_head audit_hold_queue;
154 /* queue servicing thread */
155 static struct task_struct *kauditd_task;
156 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
158 /* waitqueue for callers who are blocked on the audit backlog */
159 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
161 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
166 static char *audit_feature_names[2] = {
167 "only_unset_loginuid",
168 "loginuid_immutable",
172 * struct audit_ctl_mutex - serialize requests from userspace
173 * @lock: the mutex used for locking
174 * @owner: the task which owns the lock
177 * This is the lock struct used to ensure we only process userspace requests
178 * in an orderly fashion. We can't simply use a mutex/lock here because we
179 * need to track lock ownership so we don't end up blocking the lock owner in
180 * audit_log_start() or similar.
182 static struct audit_ctl_mutex {
187 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
188 * audit records. Since printk uses a 1024 byte buffer, this buffer
189 * should be at least that large. */
190 #define AUDIT_BUFSIZ 1024
192 /* The audit_buffer is used when formatting an audit record. The caller
193 * locks briefly to get the record off the freelist or to allocate the
194 * buffer, and locks briefly to send the buffer to the netlink layer or
195 * to place it on a transmit queue. Multiple audit_buffers can be in
196 * use simultaneously. */
197 struct audit_buffer {
198 struct sk_buff *skb; /* formatted skb ready to send */
199 struct audit_context *ctx; /* NULL or associated context */
210 * auditd_test_task - Check to see if a given task is an audit daemon
211 * @task: the task to check
214 * Return 1 if the task is a registered audit daemon, 0 otherwise.
216 int auditd_test_task(struct task_struct *task)
219 struct auditd_connection *ac;
222 ac = rcu_dereference(auditd_conn);
223 rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
230 * audit_ctl_lock - Take the audit control lock
232 void audit_ctl_lock(void)
234 mutex_lock(&audit_cmd_mutex.lock);
235 audit_cmd_mutex.owner = current;
239 * audit_ctl_unlock - Drop the audit control lock
241 void audit_ctl_unlock(void)
243 audit_cmd_mutex.owner = NULL;
244 mutex_unlock(&audit_cmd_mutex.lock);
248 * audit_ctl_owner_current - Test to see if the current task owns the lock
251 * Return true if the current task owns the audit control lock, false if it
252 * doesn't own the lock.
254 static bool audit_ctl_owner_current(void)
256 return (current == audit_cmd_mutex.owner);
260 * auditd_pid_vnr - Return the auditd PID relative to the namespace
263 * Returns the PID in relation to the namespace, 0 on failure.
265 static pid_t auditd_pid_vnr(void)
268 const struct auditd_connection *ac;
271 ac = rcu_dereference(auditd_conn);
275 pid = pid_vnr(ac->pid);
282 * audit_get_sk - Return the audit socket for the given network namespace
283 * @net: the destination network namespace
286 * Returns the sock pointer if valid, NULL otherwise. The caller must ensure
287 * that a reference is held for the network namespace while the sock is in use.
289 static struct sock *audit_get_sk(const struct net *net)
291 struct audit_net *aunet;
296 aunet = net_generic(net, audit_net_id);
300 void audit_panic(const char *message)
302 switch (audit_failure) {
303 case AUDIT_FAIL_SILENT:
305 case AUDIT_FAIL_PRINTK:
306 if (printk_ratelimit())
307 pr_err("%s\n", message);
309 case AUDIT_FAIL_PANIC:
310 panic("audit: %s\n", message);
315 static inline int audit_rate_check(void)
317 static unsigned long last_check = 0;
318 static int messages = 0;
319 static DEFINE_SPINLOCK(lock);
324 if (!audit_rate_limit) return 1;
326 spin_lock_irqsave(&lock, flags);
327 if (++messages < audit_rate_limit) {
331 if (time_after(now, last_check + HZ)) {
337 spin_unlock_irqrestore(&lock, flags);
343 * audit_log_lost - conditionally log lost audit message event
344 * @message: the message stating reason for lost audit message
346 * Emit at least 1 message per second, even if audit_rate_check is
348 * Always increment the lost messages counter.
350 void audit_log_lost(const char *message)
352 static unsigned long last_msg = 0;
353 static DEFINE_SPINLOCK(lock);
358 atomic_inc(&audit_lost);
360 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
363 spin_lock_irqsave(&lock, flags);
365 if (time_after(now, last_msg + HZ)) {
369 spin_unlock_irqrestore(&lock, flags);
373 if (printk_ratelimit())
374 pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
375 atomic_read(&audit_lost),
377 audit_backlog_limit);
378 audit_panic(message);
382 static int audit_log_config_change(char *function_name, u32 new, u32 old,
385 struct audit_buffer *ab;
388 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
391 audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
392 audit_log_session_info(ab);
393 rc = audit_log_task_context(ab);
395 allow_changes = 0; /* Something weird, deny request */
396 audit_log_format(ab, " res=%d", allow_changes);
401 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
403 int allow_changes, rc = 0;
404 u32 old = *to_change;
406 /* check if we are locked */
407 if (audit_enabled == AUDIT_LOCKED)
412 if (audit_enabled != AUDIT_OFF) {
413 rc = audit_log_config_change(function_name, new, old, allow_changes);
418 /* If we are allowed, make the change */
419 if (allow_changes == 1)
421 /* Not allowed, update reason */
427 static int audit_set_rate_limit(u32 limit)
429 return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
432 static int audit_set_backlog_limit(u32 limit)
434 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
437 static int audit_set_backlog_wait_time(u32 timeout)
439 return audit_do_config_change("audit_backlog_wait_time",
440 &audit_backlog_wait_time, timeout);
443 static int audit_set_enabled(u32 state)
446 if (state > AUDIT_LOCKED)
449 rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
451 audit_ever_enabled |= !!state;
456 static int audit_set_failure(u32 state)
458 if (state != AUDIT_FAIL_SILENT
459 && state != AUDIT_FAIL_PRINTK
460 && state != AUDIT_FAIL_PANIC)
463 return audit_do_config_change("audit_failure", &audit_failure, state);
467 * auditd_conn_free - RCU helper to release an auditd connection struct
471 * Drop any references inside the auditd connection tracking struct and free
474 static void auditd_conn_free(struct rcu_head *rcu)
476 struct auditd_connection *ac;
478 ac = container_of(rcu, struct auditd_connection, rcu);
485 * auditd_set - Set/Reset the auditd connection state
487 * @portid: auditd netlink portid
488 * @net: auditd network namespace pointer
491 * This function will obtain and drop network namespace references as
492 * necessary. Returns zero on success, negative values on failure.
494 static int auditd_set(struct pid *pid, u32 portid, struct net *net)
497 struct auditd_connection *ac_old, *ac_new;
502 ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
505 ac_new->pid = get_pid(pid);
506 ac_new->portid = portid;
507 ac_new->net = get_net(net);
509 spin_lock_irqsave(&auditd_conn_lock, flags);
510 ac_old = rcu_dereference_protected(auditd_conn,
511 lockdep_is_held(&auditd_conn_lock));
512 rcu_assign_pointer(auditd_conn, ac_new);
513 spin_unlock_irqrestore(&auditd_conn_lock, flags);
516 call_rcu(&ac_old->rcu, auditd_conn_free);
522 * kauditd_printk_skb - Print the audit record to the ring buffer
525 * Whatever the reason, this packet may not make it to the auditd connection
526 * so write it via printk so the information isn't completely lost.
528 static void kauditd_printk_skb(struct sk_buff *skb)
530 struct nlmsghdr *nlh = nlmsg_hdr(skb);
531 char *data = nlmsg_data(nlh);
533 if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
534 pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
538 * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
540 * @error: error code (unused)
543 * This should only be used by the kauditd_thread when it fails to flush the
546 static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error)
548 /* put the record back in the queue */
549 skb_queue_tail(&audit_hold_queue, skb);
553 * kauditd_hold_skb - Queue an audit record, waiting for auditd
558 * Queue the audit record, waiting for an instance of auditd. When this
559 * function is called we haven't given up yet on sending the record, but things
560 * are not looking good. The first thing we want to do is try to write the
561 * record via printk and then see if we want to try and hold on to the record
562 * and queue it, if we have room. If we want to hold on to the record, but we
563 * don't have room, record a record lost message.
565 static void kauditd_hold_skb(struct sk_buff *skb, int error)
567 /* at this point it is uncertain if we will ever send this to auditd so
568 * try to send the message via printk before we go any further */
569 kauditd_printk_skb(skb);
571 /* can we just silently drop the message? */
575 /* the hold queue is only for when the daemon goes away completely,
576 * not -EAGAIN failures; if we are in a -EAGAIN state requeue the
577 * record on the retry queue unless it's full, in which case drop it
579 if (error == -EAGAIN) {
580 if (!audit_backlog_limit ||
581 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
582 skb_queue_tail(&audit_retry_queue, skb);
585 audit_log_lost("kauditd retry queue overflow");
589 /* if we have room in the hold queue, queue the message */
590 if (!audit_backlog_limit ||
591 skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
592 skb_queue_tail(&audit_hold_queue, skb);
596 /* we have no other options - drop the message */
597 audit_log_lost("kauditd hold queue overflow");
603 * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
605 * @error: error code (unused)
608 * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
609 * but for some reason we are having problems sending it audit records so
610 * queue the given record and attempt to resend.
612 static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
614 if (!audit_backlog_limit ||
615 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
616 skb_queue_tail(&audit_retry_queue, skb);
620 /* we have to drop the record, send it via printk as a last effort */
621 kauditd_printk_skb(skb);
622 audit_log_lost("kauditd retry queue overflow");
627 * auditd_reset - Disconnect the auditd connection
628 * @ac: auditd connection state
631 * Break the auditd/kauditd connection and move all the queued records into the
632 * hold queue in case auditd reconnects. It is important to note that the @ac
633 * pointer should never be dereferenced inside this function as it may be NULL
634 * or invalid, you can only compare the memory address! If @ac is NULL then
635 * the connection will always be reset.
637 static void auditd_reset(const struct auditd_connection *ac)
641 struct auditd_connection *ac_old;
643 /* if it isn't already broken, break the connection */
644 spin_lock_irqsave(&auditd_conn_lock, flags);
645 ac_old = rcu_dereference_protected(auditd_conn,
646 lockdep_is_held(&auditd_conn_lock));
647 if (ac && ac != ac_old) {
648 /* someone already registered a new auditd connection */
649 spin_unlock_irqrestore(&auditd_conn_lock, flags);
652 rcu_assign_pointer(auditd_conn, NULL);
653 spin_unlock_irqrestore(&auditd_conn_lock, flags);
656 call_rcu(&ac_old->rcu, auditd_conn_free);
658 /* flush the retry queue to the hold queue, but don't touch the main
659 * queue since we need to process that normally for multicast */
660 while ((skb = skb_dequeue(&audit_retry_queue)))
661 kauditd_hold_skb(skb, -ECONNREFUSED);
665 * auditd_send_unicast_skb - Send a record via unicast to auditd
669 * Send a skb to the audit daemon, returns positive/zero values on success and
670 * negative values on failure; in all cases the skb will be consumed by this
671 * function. If the send results in -ECONNREFUSED the connection with auditd
672 * will be reset. This function may sleep so callers should not hold any locks
673 * where this would cause a problem.
675 static int auditd_send_unicast_skb(struct sk_buff *skb)
681 struct auditd_connection *ac;
683 /* NOTE: we can't call netlink_unicast while in the RCU section so
684 * take a reference to the network namespace and grab local
685 * copies of the namespace, the sock, and the portid; the
686 * namespace and sock aren't going to go away while we hold a
687 * reference and if the portid does become invalid after the RCU
688 * section netlink_unicast() should safely return an error */
691 ac = rcu_dereference(auditd_conn);
698 net = get_net(ac->net);
699 sk = audit_get_sk(net);
703 rc = netlink_unicast(sk, skb, portid, 0);
711 if (ac && rc == -ECONNREFUSED)
717 * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
718 * @sk: the sending sock
719 * @portid: the netlink destination
720 * @queue: the skb queue to process
721 * @retry_limit: limit on number of netlink unicast failures
722 * @skb_hook: per-skb hook for additional processing
723 * @err_hook: hook called if the skb fails the netlink unicast send
726 * Run through the given queue and attempt to send the audit records to auditd,
727 * returns zero on success, negative values on failure. It is up to the caller
728 * to ensure that the @sk is valid for the duration of this function.
731 static int kauditd_send_queue(struct sock *sk, u32 portid,
732 struct sk_buff_head *queue,
733 unsigned int retry_limit,
734 void (*skb_hook)(struct sk_buff *skb),
735 void (*err_hook)(struct sk_buff *skb, int error))
738 struct sk_buff *skb = NULL;
739 struct sk_buff *skb_tail;
740 unsigned int failed = 0;
742 /* NOTE: kauditd_thread takes care of all our locking, we just use
743 * the netlink info passed to us (e.g. sk and portid) */
745 skb_tail = skb_peek_tail(queue);
746 while ((skb != skb_tail) && (skb = skb_dequeue(queue))) {
747 /* call the skb_hook for each skb we touch */
751 /* can we send to anyone via unicast? */
754 (*err_hook)(skb, -ECONNREFUSED);
759 /* grab an extra skb reference in case of error */
761 rc = netlink_unicast(sk, skb, portid, 0);
763 /* send failed - try a few times unless fatal error */
764 if (++failed >= retry_limit ||
765 rc == -ECONNREFUSED || rc == -EPERM) {
768 (*err_hook)(skb, rc);
771 /* continue to drain the queue */
776 /* skb sent - drop the extra reference and continue */
782 return (rc >= 0 ? 0 : rc);
786 * kauditd_send_multicast_skb - Send a record to any multicast listeners
790 * Write a multicast message to anyone listening in the initial network
791 * namespace. This function doesn't consume an skb as might be expected since
792 * it has to copy it anyways.
794 static void kauditd_send_multicast_skb(struct sk_buff *skb)
796 struct sk_buff *copy;
797 struct sock *sock = audit_get_sk(&init_net);
798 struct nlmsghdr *nlh;
800 /* NOTE: we are not taking an additional reference for init_net since
801 * we don't have to worry about it going away */
803 if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
807 * The seemingly wasteful skb_copy() rather than bumping the refcount
808 * using skb_get() is necessary because non-standard mods are made to
809 * the skb by the original kaudit unicast socket send routine. The
810 * existing auditd daemon assumes this breakage. Fixing this would
811 * require co-ordinating a change in the established protocol between
812 * the kaudit kernel subsystem and the auditd userspace code. There is
813 * no reason for new multicast clients to continue with this
816 copy = skb_copy(skb, GFP_KERNEL);
819 nlh = nlmsg_hdr(copy);
820 nlh->nlmsg_len = skb->len;
822 nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
826 * kauditd_thread - Worker thread to send audit records to userspace
829 static int kauditd_thread(void *dummy)
833 struct net *net = NULL;
834 struct sock *sk = NULL;
835 struct auditd_connection *ac;
837 #define UNICAST_RETRIES 5
840 while (!kthread_should_stop()) {
841 /* NOTE: see the lock comments in auditd_send_unicast_skb() */
843 ac = rcu_dereference(auditd_conn);
848 net = get_net(ac->net);
849 sk = audit_get_sk(net);
853 /* attempt to flush the hold queue */
854 rc = kauditd_send_queue(sk, portid,
855 &audit_hold_queue, UNICAST_RETRIES,
856 NULL, kauditd_rehold_skb);
863 /* attempt to flush the retry queue */
864 rc = kauditd_send_queue(sk, portid,
865 &audit_retry_queue, UNICAST_RETRIES,
866 NULL, kauditd_hold_skb);
874 /* process the main queue - do the multicast send and attempt
875 * unicast, dump failed record sends to the retry queue; if
876 * sk == NULL due to previous failures we will just do the
877 * multicast send and move the record to the hold queue */
878 rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
879 kauditd_send_multicast_skb,
881 kauditd_retry_skb : kauditd_hold_skb));
886 /* drop our netns reference, no auditd sends past this line */
892 /* we have processed all the queues so wake everyone */
893 wake_up(&audit_backlog_wait);
895 /* NOTE: we want to wake up if there is anything on the queue,
896 * regardless of if an auditd is connected, as we need to
897 * do the multicast send and rotate records from the
898 * main queue to the retry/hold queues */
899 wait_event_freezable(kauditd_wait,
900 (skb_queue_len(&audit_queue) ? 1 : 0));
906 int audit_send_list_thread(void *_dest)
908 struct audit_netlink_list *dest = _dest;
910 struct sock *sk = audit_get_sk(dest->net);
912 /* wait for parent to finish and send an ACK */
916 while ((skb = __skb_dequeue(&dest->q)) != NULL)
917 netlink_unicast(sk, skb, dest->portid, 0);
925 struct sk_buff *audit_make_reply(int seq, int type, int done,
926 int multi, const void *payload, int size)
929 struct nlmsghdr *nlh;
931 int flags = multi ? NLM_F_MULTI : 0;
932 int t = done ? NLMSG_DONE : type;
934 skb = nlmsg_new(size, GFP_KERNEL);
938 nlh = nlmsg_put(skb, 0, seq, t, size, flags);
941 data = nlmsg_data(nlh);
942 memcpy(data, payload, size);
950 static void audit_free_reply(struct audit_reply *reply)
955 kfree_skb(reply->skb);
961 static int audit_send_reply_thread(void *arg)
963 struct audit_reply *reply = (struct audit_reply *)arg;
968 /* Ignore failure. It'll only happen if the sender goes away,
969 because our timeout is set to infinite. */
970 netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
972 audit_free_reply(reply);
977 * audit_send_reply - send an audit reply message via netlink
978 * @request_skb: skb of request we are replying to (used to target the reply)
979 * @seq: sequence number
980 * @type: audit message type
981 * @done: done (last) flag
982 * @multi: multi-part message flag
983 * @payload: payload data
984 * @size: payload size
986 * Allocates a skb, builds the netlink message, and sends it to the port id.
988 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
989 int multi, const void *payload, int size)
991 struct task_struct *tsk;
992 struct audit_reply *reply;
994 reply = kzalloc(sizeof(*reply), GFP_KERNEL);
998 reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
1001 reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
1002 reply->portid = NETLINK_CB(request_skb).portid;
1004 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
1011 audit_free_reply(reply);
1015 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
1018 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1022 /* Only support initial user namespace for now. */
1024 * We return ECONNREFUSED because it tricks userspace into thinking
1025 * that audit was not configured into the kernel. Lots of users
1026 * configure their PAM stack (because that's what the distro does)
1027 * to reject login if unable to send messages to audit. If we return
1028 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1029 * configured in and will let login proceed. If we return EPERM
1030 * userspace will reject all logins. This should be removed when we
1031 * support non init namespaces!!
1033 if (current_user_ns() != &init_user_ns)
1034 return -ECONNREFUSED;
1043 case AUDIT_GET_FEATURE:
1044 case AUDIT_SET_FEATURE:
1045 case AUDIT_LIST_RULES:
1046 case AUDIT_ADD_RULE:
1047 case AUDIT_DEL_RULE:
1048 case AUDIT_SIGNAL_INFO:
1052 case AUDIT_MAKE_EQUIV:
1053 /* Only support auditd and auditctl in initial pid namespace
1055 if (task_active_pid_ns(current) != &init_pid_ns)
1058 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1062 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1063 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1064 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1067 default: /* bad msg */
1074 static void audit_log_common_recv_msg(struct audit_context *context,
1075 struct audit_buffer **ab, u16 msg_type)
1077 uid_t uid = from_kuid(&init_user_ns, current_uid());
1078 pid_t pid = task_tgid_nr(current);
1080 if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1085 *ab = audit_log_start(context, GFP_KERNEL, msg_type);
1088 audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1089 audit_log_session_info(*ab);
1090 audit_log_task_context(*ab);
1093 static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1096 audit_log_common_recv_msg(NULL, ab, msg_type);
1099 static int is_audit_feature_set(int i)
1101 return af.features & AUDIT_FEATURE_TO_MASK(i);
1105 static int audit_get_feature(struct sk_buff *skb)
1109 seq = nlmsg_hdr(skb)->nlmsg_seq;
1111 audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1116 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1117 u32 old_lock, u32 new_lock, int res)
1119 struct audit_buffer *ab;
1121 if (audit_enabled == AUDIT_OFF)
1124 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1127 audit_log_task_info(ab);
1128 audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1129 audit_feature_names[which], !!old_feature, !!new_feature,
1130 !!old_lock, !!new_lock, res);
1134 static int audit_set_feature(struct audit_features *uaf)
1138 BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1140 /* if there is ever a version 2 we should handle that here */
1142 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1143 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1144 u32 old_feature, new_feature, old_lock, new_lock;
1146 /* if we are not changing this feature, move along */
1147 if (!(feature & uaf->mask))
1150 old_feature = af.features & feature;
1151 new_feature = uaf->features & feature;
1152 new_lock = (uaf->lock | af.lock) & feature;
1153 old_lock = af.lock & feature;
1155 /* are we changing a locked feature? */
1156 if (old_lock && (new_feature != old_feature)) {
1157 audit_log_feature_change(i, old_feature, new_feature,
1158 old_lock, new_lock, 0);
1162 /* nothing invalid, do the changes */
1163 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1164 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1165 u32 old_feature, new_feature, old_lock, new_lock;
1167 /* if we are not changing this feature, move along */
1168 if (!(feature & uaf->mask))
1171 old_feature = af.features & feature;
1172 new_feature = uaf->features & feature;
1173 old_lock = af.lock & feature;
1174 new_lock = (uaf->lock | af.lock) & feature;
1176 if (new_feature != old_feature)
1177 audit_log_feature_change(i, old_feature, new_feature,
1178 old_lock, new_lock, 1);
1181 af.features |= feature;
1183 af.features &= ~feature;
1184 af.lock |= new_lock;
1190 static int audit_replace(struct pid *pid)
1193 struct sk_buff *skb;
1195 pvnr = pid_vnr(pid);
1196 skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1199 return auditd_send_unicast_skb(skb);
1202 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
1208 struct audit_buffer *ab;
1209 u16 msg_type = nlh->nlmsg_type;
1210 struct audit_sig_info *sig_data;
1214 err = audit_netlink_ok(skb, msg_type);
1218 seq = nlh->nlmsg_seq;
1219 data = nlmsg_data(nlh);
1220 data_len = nlmsg_len(nlh);
1224 struct audit_status s;
1225 memset(&s, 0, sizeof(s));
1226 s.enabled = audit_enabled;
1227 s.failure = audit_failure;
1228 /* NOTE: use pid_vnr() so the PID is relative to the current
1230 s.pid = auditd_pid_vnr();
1231 s.rate_limit = audit_rate_limit;
1232 s.backlog_limit = audit_backlog_limit;
1233 s.lost = atomic_read(&audit_lost);
1234 s.backlog = skb_queue_len(&audit_queue);
1235 s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL;
1236 s.backlog_wait_time = audit_backlog_wait_time;
1237 s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1238 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1242 struct audit_status s;
1243 memset(&s, 0, sizeof(s));
1244 /* guard against past and future API changes */
1245 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1246 if (s.mask & AUDIT_STATUS_ENABLED) {
1247 err = audit_set_enabled(s.enabled);
1251 if (s.mask & AUDIT_STATUS_FAILURE) {
1252 err = audit_set_failure(s.failure);
1256 if (s.mask & AUDIT_STATUS_PID) {
1257 /* NOTE: we are using the vnr PID functions below
1258 * because the s.pid value is relative to the
1259 * namespace of the caller; at present this
1260 * doesn't matter much since you can really only
1261 * run auditd from the initial pid namespace, but
1262 * something to keep in mind if this changes */
1263 pid_t new_pid = s.pid;
1265 struct pid *req_pid = task_tgid(current);
1267 /* Sanity check - PID values must match. Setting
1268 * pid to 0 is how auditd ends auditing. */
1269 if (new_pid && (new_pid != pid_vnr(req_pid)))
1272 /* test the auditd connection */
1273 audit_replace(req_pid);
1275 auditd_pid = auditd_pid_vnr();
1277 /* replacing a healthy auditd is not allowed */
1279 audit_log_config_change("audit_pid",
1280 new_pid, auditd_pid, 0);
1283 /* only current auditd can unregister itself */
1284 if (pid_vnr(req_pid) != auditd_pid) {
1285 audit_log_config_change("audit_pid",
1286 new_pid, auditd_pid, 0);
1292 /* register a new auditd connection */
1293 err = auditd_set(req_pid,
1294 NETLINK_CB(skb).portid,
1295 sock_net(NETLINK_CB(skb).sk));
1296 if (audit_enabled != AUDIT_OFF)
1297 audit_log_config_change("audit_pid",
1304 /* try to process any backlog */
1305 wake_up_interruptible(&kauditd_wait);
1307 if (audit_enabled != AUDIT_OFF)
1308 audit_log_config_change("audit_pid",
1312 /* unregister the auditd connection */
1316 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1317 err = audit_set_rate_limit(s.rate_limit);
1321 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1322 err = audit_set_backlog_limit(s.backlog_limit);
1326 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1327 if (sizeof(s) > (size_t)nlh->nlmsg_len)
1329 if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1331 err = audit_set_backlog_wait_time(s.backlog_wait_time);
1335 if (s.mask == AUDIT_STATUS_LOST) {
1336 u32 lost = atomic_xchg(&audit_lost, 0);
1338 audit_log_config_change("lost", 0, lost, 1);
1341 if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1342 u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1344 audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1349 case AUDIT_GET_FEATURE:
1350 err = audit_get_feature(skb);
1354 case AUDIT_SET_FEATURE:
1355 if (data_len < sizeof(struct audit_features))
1357 err = audit_set_feature(data);
1362 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1363 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1364 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1366 /* exit early if there isn't at least one character to print */
1370 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1371 if (err == 1) { /* match or error */
1375 if (msg_type == AUDIT_USER_TTY) {
1376 err = tty_audit_push();
1380 audit_log_user_recv_msg(&ab, msg_type);
1381 if (msg_type != AUDIT_USER_TTY) {
1382 /* ensure NULL termination */
1383 str[data_len - 1] = '\0';
1384 audit_log_format(ab, " msg='%.*s'",
1385 AUDIT_MESSAGE_TEXT_MAX,
1388 audit_log_format(ab, " data=");
1389 if (str[data_len - 1] == '\0')
1391 audit_log_n_untrustedstring(ab, str, data_len);
1396 case AUDIT_ADD_RULE:
1397 case AUDIT_DEL_RULE:
1398 if (data_len < sizeof(struct audit_rule_data))
1400 if (audit_enabled == AUDIT_LOCKED) {
1401 audit_log_common_recv_msg(audit_context(), &ab,
1402 AUDIT_CONFIG_CHANGE);
1403 audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1404 msg_type == AUDIT_ADD_RULE ?
1405 "add_rule" : "remove_rule",
1410 err = audit_rule_change(msg_type, seq, data, data_len);
1412 case AUDIT_LIST_RULES:
1413 err = audit_list_rules_send(skb, seq);
1417 audit_log_common_recv_msg(audit_context(), &ab,
1418 AUDIT_CONFIG_CHANGE);
1419 audit_log_format(ab, " op=trim res=1");
1422 case AUDIT_MAKE_EQUIV: {
1425 size_t msglen = data_len;
1429 if (msglen < 2 * sizeof(u32))
1431 memcpy(sizes, bufp, 2 * sizeof(u32));
1432 bufp += 2 * sizeof(u32);
1433 msglen -= 2 * sizeof(u32);
1434 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1439 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1445 /* OK, here comes... */
1446 err = audit_tag_tree(old, new);
1448 audit_log_common_recv_msg(audit_context(), &ab,
1449 AUDIT_CONFIG_CHANGE);
1450 audit_log_format(ab, " op=make_equiv old=");
1451 audit_log_untrustedstring(ab, old);
1452 audit_log_format(ab, " new=");
1453 audit_log_untrustedstring(ab, new);
1454 audit_log_format(ab, " res=%d", !err);
1460 case AUDIT_SIGNAL_INFO:
1462 if (audit_sig_sid) {
1463 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1467 sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL);
1470 security_release_secctx(ctx, len);
1473 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1474 sig_data->pid = audit_sig_pid;
1475 if (audit_sig_sid) {
1476 memcpy(sig_data->ctx, ctx, len);
1477 security_release_secctx(ctx, len);
1479 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1480 sig_data, struct_size(sig_data, ctx, len));
1483 case AUDIT_TTY_GET: {
1484 struct audit_tty_status s;
1487 t = READ_ONCE(current->signal->audit_tty);
1488 s.enabled = t & AUDIT_TTY_ENABLE;
1489 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1491 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1494 case AUDIT_TTY_SET: {
1495 struct audit_tty_status s, old;
1496 struct audit_buffer *ab;
1499 memset(&s, 0, sizeof(s));
1500 /* guard against past and future API changes */
1501 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1502 /* check if new data is valid */
1503 if ((s.enabled != 0 && s.enabled != 1) ||
1504 (s.log_passwd != 0 && s.log_passwd != 1))
1508 t = READ_ONCE(current->signal->audit_tty);
1510 t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1511 t = xchg(¤t->signal->audit_tty, t);
1513 old.enabled = t & AUDIT_TTY_ENABLE;
1514 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1516 audit_log_common_recv_msg(audit_context(), &ab,
1517 AUDIT_CONFIG_CHANGE);
1518 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1519 " old-log_passwd=%d new-log_passwd=%d res=%d",
1520 old.enabled, s.enabled, old.log_passwd,
1521 s.log_passwd, !err);
1530 return err < 0 ? err : 0;
1534 * audit_receive - receive messages from a netlink control socket
1535 * @skb: the message buffer
1537 * Parse the provided skb and deal with any messages that may be present,
1538 * malformed skbs are discarded.
1540 static void audit_receive(struct sk_buff *skb)
1542 struct nlmsghdr *nlh;
1544 * len MUST be signed for nlmsg_next to be able to dec it below 0
1545 * if the nlmsg_len was not aligned
1550 nlh = nlmsg_hdr(skb);
1554 while (nlmsg_ok(nlh, len)) {
1555 err = audit_receive_msg(skb, nlh);
1556 /* if err or if this message says it wants a response */
1557 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1558 netlink_ack(skb, nlh, err, NULL);
1560 nlh = nlmsg_next(nlh, &len);
1564 /* can't block with the ctrl lock, so penalize the sender now */
1565 if (audit_backlog_limit &&
1566 (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1567 DECLARE_WAITQUEUE(wait, current);
1569 /* wake kauditd to try and flush the queue */
1570 wake_up_interruptible(&kauditd_wait);
1572 add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1573 set_current_state(TASK_UNINTERRUPTIBLE);
1574 schedule_timeout(audit_backlog_wait_time);
1575 remove_wait_queue(&audit_backlog_wait, &wait);
1579 /* Log information about who is connecting to the audit multicast socket */
1580 static void audit_log_multicast(int group, const char *op, int err)
1582 const struct cred *cred;
1583 struct tty_struct *tty;
1584 char comm[sizeof(current->comm)];
1585 struct audit_buffer *ab;
1590 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1594 cred = current_cred();
1595 tty = audit_get_tty();
1596 audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1597 task_pid_nr(current),
1598 from_kuid(&init_user_ns, cred->uid),
1599 from_kuid(&init_user_ns, audit_get_loginuid(current)),
1600 tty ? tty_name(tty) : "(none)",
1601 audit_get_sessionid(current));
1603 audit_log_task_context(ab); /* subj= */
1604 audit_log_format(ab, " comm=");
1605 audit_log_untrustedstring(ab, get_task_comm(comm, current));
1606 audit_log_d_path_exe(ab, current->mm); /* exe= */
1607 audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1611 /* Run custom bind function on netlink socket group connect or bind requests. */
1612 static int audit_multicast_bind(struct net *net, int group)
1616 if (!capable(CAP_AUDIT_READ))
1618 audit_log_multicast(group, "connect", err);
1622 static void audit_multicast_unbind(struct net *net, int group)
1624 audit_log_multicast(group, "disconnect", 0);
1627 static int __net_init audit_net_init(struct net *net)
1629 struct netlink_kernel_cfg cfg = {
1630 .input = audit_receive,
1631 .bind = audit_multicast_bind,
1632 .unbind = audit_multicast_unbind,
1633 .flags = NL_CFG_F_NONROOT_RECV,
1634 .groups = AUDIT_NLGRP_MAX,
1637 struct audit_net *aunet = net_generic(net, audit_net_id);
1639 aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1640 if (aunet->sk == NULL) {
1641 audit_panic("cannot initialize netlink socket in namespace");
1644 /* limit the timeout in case auditd is blocked/stopped */
1645 aunet->sk->sk_sndtimeo = HZ / 10;
1650 static void __net_exit audit_net_exit(struct net *net)
1652 struct audit_net *aunet = net_generic(net, audit_net_id);
1654 /* NOTE: you would think that we would want to check the auditd
1655 * connection and potentially reset it here if it lives in this
1656 * namespace, but since the auditd connection tracking struct holds a
1657 * reference to this namespace (see auditd_set()) we are only ever
1658 * going to get here after that connection has been released */
1660 netlink_kernel_release(aunet->sk);
1663 static struct pernet_operations audit_net_ops __net_initdata = {
1664 .init = audit_net_init,
1665 .exit = audit_net_exit,
1666 .id = &audit_net_id,
1667 .size = sizeof(struct audit_net),
1670 /* Initialize audit support at boot time. */
1671 static int __init audit_init(void)
1675 if (audit_initialized == AUDIT_DISABLED)
1678 audit_buffer_cache = kmem_cache_create("audit_buffer",
1679 sizeof(struct audit_buffer),
1680 0, SLAB_PANIC, NULL);
1682 skb_queue_head_init(&audit_queue);
1683 skb_queue_head_init(&audit_retry_queue);
1684 skb_queue_head_init(&audit_hold_queue);
1686 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1687 INIT_LIST_HEAD(&audit_inode_hash[i]);
1689 mutex_init(&audit_cmd_mutex.lock);
1690 audit_cmd_mutex.owner = NULL;
1692 pr_info("initializing netlink subsys (%s)\n",
1693 audit_default ? "enabled" : "disabled");
1694 register_pernet_subsys(&audit_net_ops);
1696 audit_initialized = AUDIT_INITIALIZED;
1698 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1699 if (IS_ERR(kauditd_task)) {
1700 int err = PTR_ERR(kauditd_task);
1701 panic("audit: failed to start the kauditd thread (%d)\n", err);
1704 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1705 "state=initialized audit_enabled=%u res=1",
1710 postcore_initcall(audit_init);
1713 * Process kernel command-line parameter at boot time.
1714 * audit={0|off} or audit={1|on}.
1716 static int __init audit_enable(char *str)
1718 if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1719 audit_default = AUDIT_OFF;
1720 else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1721 audit_default = AUDIT_ON;
1723 pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1724 audit_default = AUDIT_ON;
1727 if (audit_default == AUDIT_OFF)
1728 audit_initialized = AUDIT_DISABLED;
1729 if (audit_set_enabled(audit_default))
1730 pr_err("audit: error setting audit state (%d)\n",
1733 pr_info("%s\n", audit_default ?
1734 "enabled (after initialization)" : "disabled (until reboot)");
1738 __setup("audit=", audit_enable);
1740 /* Process kernel command-line parameter at boot time.
1741 * audit_backlog_limit=<n> */
1742 static int __init audit_backlog_limit_set(char *str)
1744 u32 audit_backlog_limit_arg;
1746 pr_info("audit_backlog_limit: ");
1747 if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1748 pr_cont("using default of %u, unable to parse %s\n",
1749 audit_backlog_limit, str);
1753 audit_backlog_limit = audit_backlog_limit_arg;
1754 pr_cont("%d\n", audit_backlog_limit);
1758 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1760 static void audit_buffer_free(struct audit_buffer *ab)
1766 kmem_cache_free(audit_buffer_cache, ab);
1769 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1770 gfp_t gfp_mask, int type)
1772 struct audit_buffer *ab;
1774 ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1778 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1781 if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1785 ab->gfp_mask = gfp_mask;
1790 audit_buffer_free(ab);
1795 * audit_serial - compute a serial number for the audit record
1797 * Compute a serial number for the audit record. Audit records are
1798 * written to user-space as soon as they are generated, so a complete
1799 * audit record may be written in several pieces. The timestamp of the
1800 * record and this serial number are used by the user-space tools to
1801 * determine which pieces belong to the same audit record. The
1802 * (timestamp,serial) tuple is unique for each syscall and is live from
1803 * syscall entry to syscall exit.
1805 * NOTE: Another possibility is to store the formatted records off the
1806 * audit context (for those records that have a context), and emit them
1807 * all at syscall exit. However, this could delay the reporting of
1808 * significant errors until syscall exit (or never, if the system
1811 unsigned int audit_serial(void)
1813 static atomic_t serial = ATOMIC_INIT(0);
1815 return atomic_inc_return(&serial);
1818 static inline void audit_get_stamp(struct audit_context *ctx,
1819 struct timespec64 *t, unsigned int *serial)
1821 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1822 ktime_get_coarse_real_ts64(t);
1823 *serial = audit_serial();
1828 * audit_log_start - obtain an audit buffer
1829 * @ctx: audit_context (may be NULL)
1830 * @gfp_mask: type of allocation
1831 * @type: audit message type
1833 * Returns audit_buffer pointer on success or NULL on error.
1835 * Obtain an audit buffer. This routine does locking to obtain the
1836 * audit buffer, but then no locking is required for calls to
1837 * audit_log_*format. If the task (ctx) is a task that is currently in a
1838 * syscall, then the syscall is marked as auditable and an audit record
1839 * will be written at syscall exit. If there is no associated task, then
1840 * task context (ctx) should be NULL.
1842 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1845 struct audit_buffer *ab;
1846 struct timespec64 t;
1847 unsigned int serial;
1849 if (audit_initialized != AUDIT_INITIALIZED)
1852 if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1855 /* NOTE: don't ever fail/sleep on these two conditions:
1856 * 1. auditd generated record - since we need auditd to drain the
1857 * queue; also, when we are checking for auditd, compare PIDs using
1858 * task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1859 * using a PID anchored in the caller's namespace
1860 * 2. generator holding the audit_cmd_mutex - we don't want to block
1861 * while holding the mutex, although we do penalize the sender
1862 * later in audit_receive() when it is safe to block
1864 if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1865 long stime = audit_backlog_wait_time;
1867 while (audit_backlog_limit &&
1868 (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1869 /* wake kauditd to try and flush the queue */
1870 wake_up_interruptible(&kauditd_wait);
1872 /* sleep if we are allowed and we haven't exhausted our
1873 * backlog wait limit */
1874 if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1877 DECLARE_WAITQUEUE(wait, current);
1879 add_wait_queue_exclusive(&audit_backlog_wait,
1881 set_current_state(TASK_UNINTERRUPTIBLE);
1882 stime = schedule_timeout(rtime);
1883 atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1884 remove_wait_queue(&audit_backlog_wait, &wait);
1886 if (audit_rate_check() && printk_ratelimit())
1887 pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1888 skb_queue_len(&audit_queue),
1889 audit_backlog_limit);
1890 audit_log_lost("backlog limit exceeded");
1896 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1898 audit_log_lost("out of memory in audit_log_start");
1902 audit_get_stamp(ab->ctx, &t, &serial);
1903 /* cancel dummy context to enable supporting records */
1906 audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1907 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1913 * audit_expand - expand skb in the audit buffer
1915 * @extra: space to add at tail of the skb
1917 * Returns 0 (no space) on failed expansion, or available space if
1920 static inline int audit_expand(struct audit_buffer *ab, int extra)
1922 struct sk_buff *skb = ab->skb;
1923 int oldtail = skb_tailroom(skb);
1924 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1925 int newtail = skb_tailroom(skb);
1928 audit_log_lost("out of memory in audit_expand");
1932 skb->truesize += newtail - oldtail;
1937 * Format an audit message into the audit buffer. If there isn't enough
1938 * room in the audit buffer, more room will be allocated and vsnprint
1939 * will be called a second time. Currently, we assume that a printk
1940 * can't format message larger than 1024 bytes, so we don't either.
1942 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1946 struct sk_buff *skb;
1954 avail = skb_tailroom(skb);
1956 avail = audit_expand(ab, AUDIT_BUFSIZ);
1960 va_copy(args2, args);
1961 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1963 /* The printk buffer is 1024 bytes long, so if we get
1964 * here and AUDIT_BUFSIZ is at least 1024, then we can
1965 * log everything that printk could have logged. */
1966 avail = audit_expand(ab,
1967 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1970 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1981 * audit_log_format - format a message into the audit buffer.
1983 * @fmt: format string
1984 * @...: optional parameters matching @fmt string
1986 * All the work is done in audit_log_vformat.
1988 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1994 va_start(args, fmt);
1995 audit_log_vformat(ab, fmt, args);
2000 * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
2001 * @ab: the audit_buffer
2002 * @buf: buffer to convert to hex
2003 * @len: length of @buf to be converted
2005 * No return value; failure to expand is silently ignored.
2007 * This function will take the passed buf and convert it into a string of
2008 * ascii hex digits. The new string is placed onto the skb.
2010 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
2013 int i, avail, new_len;
2015 struct sk_buff *skb;
2022 avail = skb_tailroom(skb);
2024 if (new_len >= avail) {
2025 /* Round the buffer request up to the next multiple */
2026 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2027 avail = audit_expand(ab, new_len);
2032 ptr = skb_tail_pointer(skb);
2033 for (i = 0; i < len; i++)
2034 ptr = hex_byte_pack_upper(ptr, buf[i]);
2036 skb_put(skb, len << 1); /* new string is twice the old string */
2040 * Format a string of no more than slen characters into the audit buffer,
2041 * enclosed in quote marks.
2043 void audit_log_n_string(struct audit_buffer *ab, const char *string,
2048 struct sk_buff *skb;
2055 avail = skb_tailroom(skb);
2056 new_len = slen + 3; /* enclosing quotes + null terminator */
2057 if (new_len > avail) {
2058 avail = audit_expand(ab, new_len);
2062 ptr = skb_tail_pointer(skb);
2064 memcpy(ptr, string, slen);
2068 skb_put(skb, slen + 2); /* don't include null terminator */
2072 * audit_string_contains_control - does a string need to be logged in hex
2073 * @string: string to be checked
2074 * @len: max length of the string to check
2076 bool audit_string_contains_control(const char *string, size_t len)
2078 const unsigned char *p;
2079 for (p = string; p < (const unsigned char *)string + len; p++) {
2080 if (*p == '"' || *p < 0x21 || *p > 0x7e)
2087 * audit_log_n_untrustedstring - log a string that may contain random characters
2089 * @len: length of string (not including trailing null)
2090 * @string: string to be logged
2092 * This code will escape a string that is passed to it if the string
2093 * contains a control character, unprintable character, double quote mark,
2094 * or a space. Unescaped strings will start and end with a double quote mark.
2095 * Strings that are escaped are printed in hex (2 digits per char).
2097 * The caller specifies the number of characters in the string to log, which may
2098 * or may not be the entire string.
2100 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2103 if (audit_string_contains_control(string, len))
2104 audit_log_n_hex(ab, string, len);
2106 audit_log_n_string(ab, string, len);
2110 * audit_log_untrustedstring - log a string that may contain random characters
2112 * @string: string to be logged
2114 * Same as audit_log_n_untrustedstring(), except that strlen is used to
2115 * determine string length.
2117 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2119 audit_log_n_untrustedstring(ab, string, strlen(string));
2122 /* This is a helper-function to print the escaped d_path */
2123 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2124 const struct path *path)
2129 audit_log_format(ab, "%s", prefix);
2131 /* We will allow 11 spaces for ' (deleted)' to be appended */
2132 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2134 audit_log_format(ab, "\"<no_memory>\"");
2137 p = d_path(path, pathname, PATH_MAX+11);
2138 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2139 /* FIXME: can we save some information here? */
2140 audit_log_format(ab, "\"<too_long>\"");
2142 audit_log_untrustedstring(ab, p);
2146 void audit_log_session_info(struct audit_buffer *ab)
2148 unsigned int sessionid = audit_get_sessionid(current);
2149 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2151 audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2154 void audit_log_key(struct audit_buffer *ab, char *key)
2156 audit_log_format(ab, " key=");
2158 audit_log_untrustedstring(ab, key);
2160 audit_log_format(ab, "(null)");
2163 int audit_log_task_context(struct audit_buffer *ab)
2170 security_current_getsecid_subj(&sid);
2174 error = security_secid_to_secctx(sid, &ctx, &len);
2176 if (error != -EINVAL)
2181 audit_log_format(ab, " subj=%s", ctx);
2182 security_release_secctx(ctx, len);
2186 audit_panic("error in audit_log_task_context");
2189 EXPORT_SYMBOL(audit_log_task_context);
2191 void audit_log_d_path_exe(struct audit_buffer *ab,
2192 struct mm_struct *mm)
2194 struct file *exe_file;
2199 exe_file = get_mm_exe_file(mm);
2203 audit_log_d_path(ab, " exe=", &exe_file->f_path);
2207 audit_log_format(ab, " exe=(null)");
2210 struct tty_struct *audit_get_tty(void)
2212 struct tty_struct *tty = NULL;
2213 unsigned long flags;
2215 spin_lock_irqsave(¤t->sighand->siglock, flags);
2216 if (current->signal)
2217 tty = tty_kref_get(current->signal->tty);
2218 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
2222 void audit_put_tty(struct tty_struct *tty)
2227 void audit_log_task_info(struct audit_buffer *ab)
2229 const struct cred *cred;
2230 char comm[sizeof(current->comm)];
2231 struct tty_struct *tty;
2236 cred = current_cred();
2237 tty = audit_get_tty();
2238 audit_log_format(ab,
2239 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2240 " euid=%u suid=%u fsuid=%u"
2241 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2242 task_ppid_nr(current),
2243 task_tgid_nr(current),
2244 from_kuid(&init_user_ns, audit_get_loginuid(current)),
2245 from_kuid(&init_user_ns, cred->uid),
2246 from_kgid(&init_user_ns, cred->gid),
2247 from_kuid(&init_user_ns, cred->euid),
2248 from_kuid(&init_user_ns, cred->suid),
2249 from_kuid(&init_user_ns, cred->fsuid),
2250 from_kgid(&init_user_ns, cred->egid),
2251 from_kgid(&init_user_ns, cred->sgid),
2252 from_kgid(&init_user_ns, cred->fsgid),
2253 tty ? tty_name(tty) : "(none)",
2254 audit_get_sessionid(current));
2256 audit_log_format(ab, " comm=");
2257 audit_log_untrustedstring(ab, get_task_comm(comm, current));
2258 audit_log_d_path_exe(ab, current->mm);
2259 audit_log_task_context(ab);
2261 EXPORT_SYMBOL(audit_log_task_info);
2264 * audit_log_path_denied - report a path restriction denial
2265 * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2266 * @operation: specific operation name
2268 void audit_log_path_denied(int type, const char *operation)
2270 struct audit_buffer *ab;
2272 if (!audit_enabled || audit_dummy_context())
2275 /* Generate log with subject, operation, outcome. */
2276 ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2279 audit_log_format(ab, "op=%s", operation);
2280 audit_log_task_info(ab);
2281 audit_log_format(ab, " res=0");
2285 /* global counter which is incremented every time something logs in */
2286 static atomic_t session_id = ATOMIC_INIT(0);
2288 static int audit_set_loginuid_perm(kuid_t loginuid)
2290 /* if we are unset, we don't need privs */
2291 if (!audit_loginuid_set(current))
2293 /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2294 if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2296 /* it is set, you need permission */
2297 if (!capable(CAP_AUDIT_CONTROL))
2299 /* reject if this is not an unset and we don't allow that */
2300 if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2301 && uid_valid(loginuid))
2306 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2307 unsigned int oldsessionid,
2308 unsigned int sessionid, int rc)
2310 struct audit_buffer *ab;
2311 uid_t uid, oldloginuid, loginuid;
2312 struct tty_struct *tty;
2317 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2321 uid = from_kuid(&init_user_ns, task_uid(current));
2322 oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2323 loginuid = from_kuid(&init_user_ns, kloginuid);
2324 tty = audit_get_tty();
2326 audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2327 audit_log_task_context(ab);
2328 audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2329 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2330 oldsessionid, sessionid, !rc);
2336 * audit_set_loginuid - set current task's loginuid
2337 * @loginuid: loginuid value
2341 * Called (set) from fs/proc/base.c::proc_loginuid_write().
2343 int audit_set_loginuid(kuid_t loginuid)
2345 unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2349 oldloginuid = audit_get_loginuid(current);
2350 oldsessionid = audit_get_sessionid(current);
2352 rc = audit_set_loginuid_perm(loginuid);
2356 /* are we setting or clearing? */
2357 if (uid_valid(loginuid)) {
2358 sessionid = (unsigned int)atomic_inc_return(&session_id);
2359 if (unlikely(sessionid == AUDIT_SID_UNSET))
2360 sessionid = (unsigned int)atomic_inc_return(&session_id);
2363 current->sessionid = sessionid;
2364 current->loginuid = loginuid;
2366 audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2371 * audit_signal_info - record signal info for shutting down audit subsystem
2372 * @sig: signal value
2373 * @t: task being signaled
2375 * If the audit subsystem is being terminated, record the task (pid)
2376 * and uid that is doing that.
2378 int audit_signal_info(int sig, struct task_struct *t)
2380 kuid_t uid = current_uid(), auid;
2382 if (auditd_test_task(t) &&
2383 (sig == SIGTERM || sig == SIGHUP ||
2384 sig == SIGUSR1 || sig == SIGUSR2)) {
2385 audit_sig_pid = task_tgid_nr(current);
2386 auid = audit_get_loginuid(current);
2387 if (uid_valid(auid))
2388 audit_sig_uid = auid;
2390 audit_sig_uid = uid;
2391 security_current_getsecid_subj(&audit_sig_sid);
2394 return audit_signal_info_syscall(t);
2398 * audit_log_end - end one audit record
2399 * @ab: the audit_buffer
2401 * We can not do a netlink send inside an irq context because it blocks (last
2402 * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2403 * queue and a kthread is scheduled to remove them from the queue outside the
2404 * irq context. May be called in any context.
2406 void audit_log_end(struct audit_buffer *ab)
2408 struct sk_buff *skb;
2409 struct nlmsghdr *nlh;
2414 if (audit_rate_check()) {
2418 /* setup the netlink header, see the comments in
2419 * kauditd_send_multicast_skb() for length quirks */
2420 nlh = nlmsg_hdr(skb);
2421 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2423 /* queue the netlink packet and poke the kauditd thread */
2424 skb_queue_tail(&audit_queue, skb);
2425 wake_up_interruptible(&kauditd_wait);
2427 audit_log_lost("rate limit exceeded");
2429 audit_buffer_free(ab);
2433 * audit_log - Log an audit record
2434 * @ctx: audit context
2435 * @gfp_mask: type of allocation
2436 * @type: audit message type
2437 * @fmt: format string to use
2438 * @...: variable parameters matching the format string
2440 * This is a convenience function that calls audit_log_start,
2441 * audit_log_vformat, and audit_log_end. It may be called
2444 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2445 const char *fmt, ...)
2447 struct audit_buffer *ab;
2450 ab = audit_log_start(ctx, gfp_mask, type);
2452 va_start(args, fmt);
2453 audit_log_vformat(ab, fmt, args);
2459 EXPORT_SYMBOL(audit_log_start);
2460 EXPORT_SYMBOL(audit_log_end);
2461 EXPORT_SYMBOL(audit_log_format);
2462 EXPORT_SYMBOL(audit_log);