1 /* audit.c -- Auditing support
2 * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
3 * System-call specific features have moved to auditsc.c
5 * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 * Written by Rickard E. (Rik) Faith <faith@redhat.com>
24 * Goals: 1) Integrate fully with Security Modules.
25 * 2) Minimal run-time overhead:
26 * a) Minimal when syscall auditing is disabled (audit_enable=0).
27 * b) Small when syscall auditing is enabled and no audit record
28 * is generated (defer as much work as possible to record
30 * i) context is allocated,
31 * ii) names from getname are stored without a copy, and
32 * iii) inode information stored from path_lookup.
33 * 3) Ability to disable syscall auditing at boot time (audit=0).
34 * 4) Usable by other parts of the kernel (if audit_log* is called,
35 * then a syscall record will be generated automatically for the
37 * 5) Netlink interface to user-space.
38 * 6) Support low-overhead kernel-based filtering to minimize the
39 * information that must be passed to user-space.
41 * Example user-space utilities: http://people.redhat.com/sgrubb/audit/
44 #include <linux/init.h>
45 #include <asm/types.h>
46 #include <asm/atomic.h>
48 #include <linux/module.h>
49 #include <linux/err.h>
50 #include <linux/kthread.h>
52 #include <linux/audit.h>
55 #include <net/netlink.h>
56 #include <linux/skbuff.h>
57 #include <linux/netlink.h>
58 #include <linux/inotify.h>
59 #include <linux/freezer.h>
60 #include <linux/tty.h>
64 /* No auditing will take place until audit_initialized != 0.
65 * (Initialization happens after skb_init is called.) */
66 static int audit_initialized;
70 #define AUDIT_LOCKED 2
72 int audit_ever_enabled;
74 /* Default state when kernel boots without any parameters. */
75 static int audit_default;
77 /* If auditing cannot proceed, audit_failure selects what happens. */
78 static int audit_failure = AUDIT_FAIL_PRINTK;
81 * If audit records are to be written to the netlink socket, audit_pid
82 * contains the pid of the auditd process and audit_nlk_pid contains
83 * the pid to use to send netlink messages to that process.
86 static int audit_nlk_pid;
88 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
89 * to that number per second. This prevents DoS attacks, but results in
90 * audit records being dropped. */
91 static int audit_rate_limit;
93 /* Number of outstanding audit_buffers allowed. */
94 static int audit_backlog_limit = 64;
95 static int audit_backlog_wait_time = 60 * HZ;
96 static int audit_backlog_wait_overflow = 0;
98 /* The identity of the user shutting down the audit system. */
99 uid_t audit_sig_uid = -1;
100 pid_t audit_sig_pid = -1;
101 u32 audit_sig_sid = 0;
103 /* Records can be lost in several ways:
104 0) [suppressed in audit_alloc]
105 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
106 2) out of memory in audit_log_move [alloc_skb]
107 3) suppressed due to audit_rate_limit
108 4) suppressed due to audit_backlog_limit
110 static atomic_t audit_lost = ATOMIC_INIT(0);
112 /* The netlink socket. */
113 static struct sock *audit_sock;
115 /* Inotify handle. */
116 struct inotify_handle *audit_ih;
118 /* Hash for inode-based rules */
119 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
121 /* The audit_freelist is a list of pre-allocated audit buffers (if more
122 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
123 * being placed on the freelist). */
124 static DEFINE_SPINLOCK(audit_freelist_lock);
125 static int audit_freelist_count;
126 static LIST_HEAD(audit_freelist);
128 static struct sk_buff_head audit_skb_queue;
129 /* queue of skbs to send to auditd when/if it comes back */
130 static struct sk_buff_head audit_skb_hold_queue;
131 static struct task_struct *kauditd_task;
132 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
133 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
135 /* Serialize requests from userspace. */
136 static DEFINE_MUTEX(audit_cmd_mutex);
138 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
139 * audit records. Since printk uses a 1024 byte buffer, this buffer
140 * should be at least that large. */
141 #define AUDIT_BUFSIZ 1024
143 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
144 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
145 #define AUDIT_MAXFREE (2*NR_CPUS)
147 /* The audit_buffer is used when formatting an audit record. The caller
148 * locks briefly to get the record off the freelist or to allocate the
149 * buffer, and locks briefly to send the buffer to the netlink layer or
150 * to place it on a transmit queue. Multiple audit_buffers can be in
151 * use simultaneously. */
152 struct audit_buffer {
153 struct list_head list;
154 struct sk_buff *skb; /* formatted skb ready to send */
155 struct audit_context *ctx; /* NULL or associated context */
159 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
162 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
163 nlh->nlmsg_pid = pid;
167 void audit_panic(const char *message)
169 switch (audit_failure)
171 case AUDIT_FAIL_SILENT:
173 case AUDIT_FAIL_PRINTK:
174 if (printk_ratelimit())
175 printk(KERN_ERR "audit: %s\n", message);
177 case AUDIT_FAIL_PANIC:
178 /* test audit_pid since printk is always losey, why bother? */
180 panic("audit: %s\n", message);
185 static inline int audit_rate_check(void)
187 static unsigned long last_check = 0;
188 static int messages = 0;
189 static DEFINE_SPINLOCK(lock);
192 unsigned long elapsed;
195 if (!audit_rate_limit) return 1;
197 spin_lock_irqsave(&lock, flags);
198 if (++messages < audit_rate_limit) {
202 elapsed = now - last_check;
209 spin_unlock_irqrestore(&lock, flags);
215 * audit_log_lost - conditionally log lost audit message event
216 * @message: the message stating reason for lost audit message
218 * Emit at least 1 message per second, even if audit_rate_check is
220 * Always increment the lost messages counter.
222 void audit_log_lost(const char *message)
224 static unsigned long last_msg = 0;
225 static DEFINE_SPINLOCK(lock);
230 atomic_inc(&audit_lost);
232 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
235 spin_lock_irqsave(&lock, flags);
237 if (now - last_msg > HZ) {
241 spin_unlock_irqrestore(&lock, flags);
245 if (printk_ratelimit())
247 "audit: audit_lost=%d audit_rate_limit=%d "
248 "audit_backlog_limit=%d\n",
249 atomic_read(&audit_lost),
251 audit_backlog_limit);
252 audit_panic(message);
256 static int audit_log_config_change(char *function_name, int new, int old,
257 uid_t loginuid, u32 sessionid, u32 sid,
260 struct audit_buffer *ab;
263 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
264 audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
265 old, loginuid, sessionid);
270 rc = security_secid_to_secctx(sid, &ctx, &len);
272 audit_log_format(ab, " sid=%u", sid);
273 allow_changes = 0; /* Something weird, deny request */
275 audit_log_format(ab, " subj=%s", ctx);
276 security_release_secctx(ctx, len);
279 audit_log_format(ab, " res=%d", allow_changes);
284 static int audit_do_config_change(char *function_name, int *to_change,
285 int new, uid_t loginuid, u32 sessionid,
288 int allow_changes, rc = 0, old = *to_change;
290 /* check if we are locked */
291 if (audit_enabled == AUDIT_LOCKED)
296 if (audit_enabled != AUDIT_OFF) {
297 rc = audit_log_config_change(function_name, new, old, loginuid,
298 sessionid, sid, allow_changes);
303 /* If we are allowed, make the change */
304 if (allow_changes == 1)
306 /* Not allowed, update reason */
312 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
315 return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
316 limit, loginuid, sessionid, sid);
319 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
322 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
323 limit, loginuid, sessionid, sid);
326 static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
329 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
332 rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
333 loginuid, sessionid, sid);
336 audit_ever_enabled |= !!state;
341 static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
343 if (state != AUDIT_FAIL_SILENT
344 && state != AUDIT_FAIL_PRINTK
345 && state != AUDIT_FAIL_PANIC)
348 return audit_do_config_change("audit_failure", &audit_failure, state,
349 loginuid, sessionid, sid);
353 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
354 * already have been sent via prink/syslog and so if these messages are dropped
355 * it is not a huge concern since we already passed the audit_log_lost()
356 * notification and stuff. This is just nice to get audit messages during
357 * boot before auditd is running or messages generated while auditd is stopped.
358 * This only holds messages is audit_default is set, aka booting with audit=1
359 * or building your kernel that way.
361 static void audit_hold_skb(struct sk_buff *skb)
364 skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
365 skb_queue_tail(&audit_skb_hold_queue, skb);
370 static void kauditd_send_skb(struct sk_buff *skb)
373 /* take a reference in case we can't send it and we want to hold it */
375 err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
377 BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
378 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
379 audit_log_lost("auditd dissapeared\n");
381 /* we might get lucky and get this in the next auditd */
384 /* drop the extra reference if sent ok */
388 static int kauditd_thread(void *dummy)
393 while (!kthread_should_stop()) {
395 * if auditd just started drain the queue of messages already
396 * sent to syslog/printk. remember loss here is ok. we already
397 * called audit_log_lost() if it didn't go out normally. so the
398 * race between the skb_dequeue and the next check for audit_pid
401 * if you ever find kauditd to be too slow we can get a perf win
402 * by doing our own locking and keeping better track if there
403 * are messages in this queue. I don't see the need now, but
404 * in 5 years when I want to play with this again I'll see this
405 * note and still have no friggin idea what i'm thinking today.
407 if (audit_default && audit_pid) {
408 skb = skb_dequeue(&audit_skb_hold_queue);
410 while (skb && audit_pid) {
411 kauditd_send_skb(skb);
412 skb = skb_dequeue(&audit_skb_hold_queue);
417 skb = skb_dequeue(&audit_skb_queue);
418 wake_up(&audit_backlog_wait);
421 kauditd_send_skb(skb);
423 if (printk_ratelimit())
424 printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0));
426 audit_log_lost("printk limit exceeded\n");
431 DECLARE_WAITQUEUE(wait, current);
432 set_current_state(TASK_INTERRUPTIBLE);
433 add_wait_queue(&kauditd_wait, &wait);
435 if (!skb_queue_len(&audit_skb_queue)) {
440 __set_current_state(TASK_RUNNING);
441 remove_wait_queue(&kauditd_wait, &wait);
447 static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
449 struct task_struct *tsk;
452 read_lock(&tasklist_lock);
453 tsk = find_task_by_pid(pid);
459 spin_lock_irq(&tsk->sighand->siglock);
460 if (!tsk->signal->audit_tty)
462 spin_unlock_irq(&tsk->sighand->siglock);
466 tty_audit_push_task(tsk, loginuid, sessionid);
468 read_unlock(&tasklist_lock);
472 int audit_send_list(void *_dest)
474 struct audit_netlink_list *dest = _dest;
478 /* wait for parent to finish and send an ACK */
479 mutex_lock(&audit_cmd_mutex);
480 mutex_unlock(&audit_cmd_mutex);
482 while ((skb = __skb_dequeue(&dest->q)) != NULL)
483 netlink_unicast(audit_sock, skb, pid, 0);
490 #ifdef CONFIG_AUDIT_TREE
491 static int prune_tree_thread(void *unused)
493 mutex_lock(&audit_cmd_mutex);
495 mutex_unlock(&audit_cmd_mutex);
499 void audit_schedule_prune(void)
501 kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
505 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
506 int multi, void *payload, int size)
509 struct nlmsghdr *nlh;
510 int len = NLMSG_SPACE(size);
512 int flags = multi ? NLM_F_MULTI : 0;
513 int t = done ? NLMSG_DONE : type;
515 skb = alloc_skb(len, GFP_KERNEL);
519 nlh = NLMSG_PUT(skb, pid, seq, t, size);
520 nlh->nlmsg_flags = flags;
521 data = NLMSG_DATA(nlh);
522 memcpy(data, payload, size);
525 nlmsg_failure: /* Used by NLMSG_PUT */
532 * audit_send_reply - send an audit reply message via netlink
533 * @pid: process id to send reply to
534 * @seq: sequence number
535 * @type: audit message type
536 * @done: done (last) flag
537 * @multi: multi-part message flag
538 * @payload: payload data
539 * @size: payload size
541 * Allocates an skb, builds the netlink message, and sends it to the pid.
542 * No failure notifications.
544 void audit_send_reply(int pid, int seq, int type, int done, int multi,
545 void *payload, int size)
548 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
551 /* Ignore failure. It'll only happen if the sender goes away,
552 because our timeout is set to infinite. */
553 netlink_unicast(audit_sock, skb, pid, 0);
558 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
561 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
568 case AUDIT_LIST_RULES:
574 case AUDIT_SIGNAL_INFO:
578 case AUDIT_MAKE_EQUIV:
579 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
583 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
584 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
585 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
588 default: /* bad msg */
595 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
596 u32 pid, u32 uid, uid_t auid, u32 ses,
603 if (!audit_enabled) {
608 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
609 audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u",
610 pid, uid, auid, ses);
612 rc = security_secid_to_secctx(sid, &ctx, &len);
614 audit_log_format(*ab, " ssid=%u", sid);
616 audit_log_format(*ab, " subj=%s", ctx);
617 security_release_secctx(ctx, len);
624 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
626 u32 uid, pid, seq, sid;
628 struct audit_status *status_get, status_set;
630 struct audit_buffer *ab;
631 u16 msg_type = nlh->nlmsg_type;
632 uid_t loginuid; /* loginuid of sender */
634 struct audit_sig_info *sig_data;
638 err = audit_netlink_ok(skb, msg_type);
642 /* As soon as there's any sign of userspace auditd,
643 * start kauditd to talk to it */
645 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
646 if (IS_ERR(kauditd_task)) {
647 err = PTR_ERR(kauditd_task);
652 pid = NETLINK_CREDS(skb)->pid;
653 uid = NETLINK_CREDS(skb)->uid;
654 loginuid = NETLINK_CB(skb).loginuid;
655 sessionid = NETLINK_CB(skb).sessionid;
656 sid = NETLINK_CB(skb).sid;
657 seq = nlh->nlmsg_seq;
658 data = NLMSG_DATA(nlh);
662 status_set.enabled = audit_enabled;
663 status_set.failure = audit_failure;
664 status_set.pid = audit_pid;
665 status_set.rate_limit = audit_rate_limit;
666 status_set.backlog_limit = audit_backlog_limit;
667 status_set.lost = atomic_read(&audit_lost);
668 status_set.backlog = skb_queue_len(&audit_skb_queue);
669 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
670 &status_set, sizeof(status_set));
673 if (nlh->nlmsg_len < sizeof(struct audit_status))
675 status_get = (struct audit_status *)data;
676 if (status_get->mask & AUDIT_STATUS_ENABLED) {
677 err = audit_set_enabled(status_get->enabled,
678 loginuid, sessionid, sid);
679 if (err < 0) return err;
681 if (status_get->mask & AUDIT_STATUS_FAILURE) {
682 err = audit_set_failure(status_get->failure,
683 loginuid, sessionid, sid);
684 if (err < 0) return err;
686 if (status_get->mask & AUDIT_STATUS_PID) {
687 int new_pid = status_get->pid;
689 if (audit_enabled != AUDIT_OFF)
690 audit_log_config_change("audit_pid", new_pid,
695 audit_nlk_pid = NETLINK_CB(skb).pid;
697 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
698 err = audit_set_rate_limit(status_get->rate_limit,
699 loginuid, sessionid, sid);
700 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
701 err = audit_set_backlog_limit(status_get->backlog_limit,
702 loginuid, sessionid, sid);
705 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
706 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
707 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
710 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
713 if (msg_type == AUDIT_USER_TTY) {
714 err = audit_prepare_user_tty(pid, loginuid,
719 audit_log_common_recv_msg(&ab, msg_type, pid, uid,
720 loginuid, sessionid, sid);
722 if (msg_type != AUDIT_USER_TTY)
723 audit_log_format(ab, " msg='%.1024s'",
728 audit_log_format(ab, " msg=");
729 size = nlmsg_len(nlh);
730 audit_log_n_untrustedstring(ab, size,
733 audit_set_pid(ab, pid);
739 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
741 if (audit_enabled == AUDIT_LOCKED) {
742 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
743 uid, loginuid, sessionid, sid);
745 audit_log_format(ab, " audit_enabled=%d res=0",
752 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
753 uid, seq, data, nlmsg_len(nlh),
754 loginuid, sessionid, sid);
758 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
760 if (audit_enabled == AUDIT_LOCKED) {
761 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
762 uid, loginuid, sessionid, sid);
764 audit_log_format(ab, " audit_enabled=%d res=0",
770 case AUDIT_LIST_RULES:
771 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
772 uid, seq, data, nlmsg_len(nlh),
773 loginuid, sessionid, sid);
778 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
779 uid, loginuid, sessionid, sid);
781 audit_log_format(ab, " op=trim res=1");
784 case AUDIT_MAKE_EQUIV: {
787 size_t len = nlmsg_len(nlh);
791 if (len < 2 * sizeof(u32))
793 memcpy(sizes, bufp, 2 * sizeof(u32));
794 bufp += 2 * sizeof(u32);
795 len -= 2 * sizeof(u32);
796 old = audit_unpack_string(&bufp, &len, sizes[0]);
801 new = audit_unpack_string(&bufp, &len, sizes[1]);
807 /* OK, here comes... */
808 err = audit_tag_tree(old, new);
810 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
811 uid, loginuid, sessionid, sid);
813 audit_log_format(ab, " op=make_equiv old=");
814 audit_log_untrustedstring(ab, old);
815 audit_log_format(ab, " new=");
816 audit_log_untrustedstring(ab, new);
817 audit_log_format(ab, " res=%d", !err);
823 case AUDIT_SIGNAL_INFO:
824 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
827 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
829 security_release_secctx(ctx, len);
832 sig_data->uid = audit_sig_uid;
833 sig_data->pid = audit_sig_pid;
834 memcpy(sig_data->ctx, ctx, len);
835 security_release_secctx(ctx, len);
836 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
837 0, 0, sig_data, sizeof(*sig_data) + len);
840 case AUDIT_TTY_GET: {
841 struct audit_tty_status s;
842 struct task_struct *tsk;
844 read_lock(&tasklist_lock);
845 tsk = find_task_by_pid(pid);
849 spin_lock_irq(&tsk->sighand->siglock);
850 s.enabled = tsk->signal->audit_tty != 0;
851 spin_unlock_irq(&tsk->sighand->siglock);
853 read_unlock(&tasklist_lock);
854 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0,
858 case AUDIT_TTY_SET: {
859 struct audit_tty_status *s;
860 struct task_struct *tsk;
862 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
865 if (s->enabled != 0 && s->enabled != 1)
867 read_lock(&tasklist_lock);
868 tsk = find_task_by_pid(pid);
872 spin_lock_irq(&tsk->sighand->siglock);
873 tsk->signal->audit_tty = s->enabled != 0;
874 spin_unlock_irq(&tsk->sighand->siglock);
876 read_unlock(&tasklist_lock);
884 return err < 0 ? err : 0;
888 * Get message from skb (based on rtnetlink_rcv_skb). Each message is
889 * processed by audit_receive_msg. Malformed skbs with wrong length are
890 * discarded silently.
892 static void audit_receive_skb(struct sk_buff *skb)
895 struct nlmsghdr *nlh;
898 while (skb->len >= NLMSG_SPACE(0)) {
899 nlh = nlmsg_hdr(skb);
900 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
902 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
905 if ((err = audit_receive_msg(skb, nlh))) {
906 netlink_ack(skb, nlh, err);
907 } else if (nlh->nlmsg_flags & NLM_F_ACK)
908 netlink_ack(skb, nlh, 0);
913 /* Receive messages from netlink socket. */
914 static void audit_receive(struct sk_buff *skb)
916 mutex_lock(&audit_cmd_mutex);
917 audit_receive_skb(skb);
918 mutex_unlock(&audit_cmd_mutex);
921 #ifdef CONFIG_AUDITSYSCALL
922 static const struct inotify_operations audit_inotify_ops = {
923 .handle_event = audit_handle_ievent,
924 .destroy_watch = audit_free_parent,
928 /* Initialize audit support at boot time. */
929 static int __init audit_init(void)
933 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
934 audit_default ? "enabled" : "disabled");
935 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
936 audit_receive, NULL, THIS_MODULE);
938 audit_panic("cannot initialize netlink socket");
940 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
942 skb_queue_head_init(&audit_skb_queue);
943 skb_queue_head_init(&audit_skb_hold_queue);
944 audit_initialized = 1;
945 audit_enabled = audit_default;
946 audit_ever_enabled |= !!audit_default;
948 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
950 #ifdef CONFIG_AUDITSYSCALL
951 audit_ih = inotify_init(&audit_inotify_ops);
952 if (IS_ERR(audit_ih))
953 audit_panic("cannot initialize inotify handle");
956 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
957 INIT_LIST_HEAD(&audit_inode_hash[i]);
961 __initcall(audit_init);
963 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
964 static int __init audit_enable(char *str)
966 audit_default = !!simple_strtol(str, NULL, 0);
967 printk(KERN_INFO "audit: %s%s\n",
968 audit_default ? "enabled" : "disabled",
969 audit_initialized ? "" : " (after initialization)");
970 if (audit_initialized) {
971 audit_enabled = audit_default;
972 audit_ever_enabled |= !!audit_default;
977 __setup("audit=", audit_enable);
979 static void audit_buffer_free(struct audit_buffer *ab)
989 spin_lock_irqsave(&audit_freelist_lock, flags);
990 if (audit_freelist_count > AUDIT_MAXFREE)
993 audit_freelist_count++;
994 list_add(&ab->list, &audit_freelist);
996 spin_unlock_irqrestore(&audit_freelist_lock, flags);
999 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1000 gfp_t gfp_mask, int type)
1002 unsigned long flags;
1003 struct audit_buffer *ab = NULL;
1004 struct nlmsghdr *nlh;
1006 spin_lock_irqsave(&audit_freelist_lock, flags);
1007 if (!list_empty(&audit_freelist)) {
1008 ab = list_entry(audit_freelist.next,
1009 struct audit_buffer, list);
1010 list_del(&ab->list);
1011 --audit_freelist_count;
1013 spin_unlock_irqrestore(&audit_freelist_lock, flags);
1016 ab = kmalloc(sizeof(*ab), gfp_mask);
1021 ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
1026 ab->gfp_mask = gfp_mask;
1027 nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
1028 nlh->nlmsg_type = type;
1029 nlh->nlmsg_flags = 0;
1034 audit_buffer_free(ab);
1039 * audit_serial - compute a serial number for the audit record
1041 * Compute a serial number for the audit record. Audit records are
1042 * written to user-space as soon as they are generated, so a complete
1043 * audit record may be written in several pieces. The timestamp of the
1044 * record and this serial number are used by the user-space tools to
1045 * determine which pieces belong to the same audit record. The
1046 * (timestamp,serial) tuple is unique for each syscall and is live from
1047 * syscall entry to syscall exit.
1049 * NOTE: Another possibility is to store the formatted records off the
1050 * audit context (for those records that have a context), and emit them
1051 * all at syscall exit. However, this could delay the reporting of
1052 * significant errors until syscall exit (or never, if the system
1055 unsigned int audit_serial(void)
1057 static DEFINE_SPINLOCK(serial_lock);
1058 static unsigned int serial = 0;
1060 unsigned long flags;
1063 spin_lock_irqsave(&serial_lock, flags);
1066 } while (unlikely(!ret));
1067 spin_unlock_irqrestore(&serial_lock, flags);
1072 static inline void audit_get_stamp(struct audit_context *ctx,
1073 struct timespec *t, unsigned int *serial)
1076 auditsc_get_stamp(ctx, t, serial);
1079 *serial = audit_serial();
1083 /* Obtain an audit buffer. This routine does locking to obtain the
1084 * audit buffer, but then no locking is required for calls to
1085 * audit_log_*format. If the tsk is a task that is currently in a
1086 * syscall, then the syscall is marked as auditable and an audit record
1087 * will be written at syscall exit. If there is no associated task, tsk
1088 * should be NULL. */
1091 * audit_log_start - obtain an audit buffer
1092 * @ctx: audit_context (may be NULL)
1093 * @gfp_mask: type of allocation
1094 * @type: audit message type
1096 * Returns audit_buffer pointer on success or NULL on error.
1098 * Obtain an audit buffer. This routine does locking to obtain the
1099 * audit buffer, but then no locking is required for calls to
1100 * audit_log_*format. If the task (ctx) is a task that is currently in a
1101 * syscall, then the syscall is marked as auditable and an audit record
1102 * will be written at syscall exit. If there is no associated task, then
1103 * task context (ctx) should be NULL.
1105 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1108 struct audit_buffer *ab = NULL;
1110 unsigned int uninitialized_var(serial);
1112 unsigned long timeout_start = jiffies;
1114 if (!audit_initialized)
1117 if (unlikely(audit_filter_type(type)))
1120 if (gfp_mask & __GFP_WAIT)
1123 reserve = 5; /* Allow atomic callers to go up to five
1124 entries over the normal backlog limit */
1126 while (audit_backlog_limit
1127 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1128 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1129 && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1131 /* Wait for auditd to drain the queue a little */
1132 DECLARE_WAITQUEUE(wait, current);
1133 set_current_state(TASK_INTERRUPTIBLE);
1134 add_wait_queue(&audit_backlog_wait, &wait);
1136 if (audit_backlog_limit &&
1137 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1138 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1140 __set_current_state(TASK_RUNNING);
1141 remove_wait_queue(&audit_backlog_wait, &wait);
1144 if (audit_rate_check() && printk_ratelimit())
1146 "audit: audit_backlog=%d > "
1147 "audit_backlog_limit=%d\n",
1148 skb_queue_len(&audit_skb_queue),
1149 audit_backlog_limit);
1150 audit_log_lost("backlog limit exceeded");
1151 audit_backlog_wait_time = audit_backlog_wait_overflow;
1152 wake_up(&audit_backlog_wait);
1156 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1158 audit_log_lost("out of memory in audit_log_start");
1162 audit_get_stamp(ab->ctx, &t, &serial);
1164 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1165 t.tv_sec, t.tv_nsec/1000000, serial);
1170 * audit_expand - expand skb in the audit buffer
1172 * @extra: space to add at tail of the skb
1174 * Returns 0 (no space) on failed expansion, or available space if
1177 static inline int audit_expand(struct audit_buffer *ab, int extra)
1179 struct sk_buff *skb = ab->skb;
1180 int oldtail = skb_tailroom(skb);
1181 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1182 int newtail = skb_tailroom(skb);
1185 audit_log_lost("out of memory in audit_expand");
1189 skb->truesize += newtail - oldtail;
1194 * Format an audit message into the audit buffer. If there isn't enough
1195 * room in the audit buffer, more room will be allocated and vsnprint
1196 * will be called a second time. Currently, we assume that a printk
1197 * can't format message larger than 1024 bytes, so we don't either.
1199 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1203 struct sk_buff *skb;
1211 avail = skb_tailroom(skb);
1213 avail = audit_expand(ab, AUDIT_BUFSIZ);
1217 va_copy(args2, args);
1218 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1220 /* The printk buffer is 1024 bytes long, so if we get
1221 * here and AUDIT_BUFSIZ is at least 1024, then we can
1222 * log everything that printk could have logged. */
1223 avail = audit_expand(ab,
1224 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1227 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1237 * audit_log_format - format a message into the audit buffer.
1239 * @fmt: format string
1240 * @...: optional parameters matching @fmt string
1242 * All the work is done in audit_log_vformat.
1244 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1250 va_start(args, fmt);
1251 audit_log_vformat(ab, fmt, args);
1256 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1257 * @ab: the audit_buffer
1258 * @buf: buffer to convert to hex
1259 * @len: length of @buf to be converted
1261 * No return value; failure to expand is silently ignored.
1263 * This function will take the passed buf and convert it into a string of
1264 * ascii hex digits. The new string is placed onto the skb.
1266 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1269 int i, avail, new_len;
1271 struct sk_buff *skb;
1272 static const unsigned char *hex = "0123456789ABCDEF";
1279 avail = skb_tailroom(skb);
1281 if (new_len >= avail) {
1282 /* Round the buffer request up to the next multiple */
1283 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1284 avail = audit_expand(ab, new_len);
1289 ptr = skb_tail_pointer(skb);
1290 for (i=0; i<len; i++) {
1291 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1292 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1295 skb_put(skb, len << 1); /* new string is twice the old string */
1299 * Format a string of no more than slen characters into the audit buffer,
1300 * enclosed in quote marks.
1302 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1307 struct sk_buff *skb;
1314 avail = skb_tailroom(skb);
1315 new_len = slen + 3; /* enclosing quotes + null terminator */
1316 if (new_len > avail) {
1317 avail = audit_expand(ab, new_len);
1321 ptr = skb_tail_pointer(skb);
1323 memcpy(ptr, string, slen);
1327 skb_put(skb, slen + 2); /* don't include null terminator */
1331 * audit_string_contains_control - does a string need to be logged in hex
1332 * @string: string to be checked
1333 * @len: max length of the string to check
1335 int audit_string_contains_control(const char *string, size_t len)
1337 const unsigned char *p;
1338 for (p = string; p < (const unsigned char *)string + len && *p; p++) {
1339 if (*p == '"' || *p < 0x21 || *p > 0x7f)
1346 * audit_log_n_untrustedstring - log a string that may contain random characters
1348 * @len: length of string (not including trailing null)
1349 * @string: string to be logged
1351 * This code will escape a string that is passed to it if the string
1352 * contains a control character, unprintable character, double quote mark,
1353 * or a space. Unescaped strings will start and end with a double quote mark.
1354 * Strings that are escaped are printed in hex (2 digits per char).
1356 * The caller specifies the number of characters in the string to log, which may
1357 * or may not be the entire string.
1359 void audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1362 if (audit_string_contains_control(string, len))
1363 audit_log_hex(ab, string, len);
1365 audit_log_n_string(ab, len, string);
1369 * audit_log_untrustedstring - log a string that may contain random characters
1371 * @string: string to be logged
1373 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1374 * determine string length.
1376 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1378 audit_log_n_untrustedstring(ab, strlen(string), string);
1381 /* This is a helper-function to print the escaped d_path */
1382 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1388 audit_log_format(ab, " %s", prefix);
1390 /* We will allow 11 spaces for ' (deleted)' to be appended */
1391 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1393 audit_log_format(ab, "<no memory>");
1396 p = d_path(path, pathname, PATH_MAX+11);
1397 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1398 /* FIXME: can we save some information here? */
1399 audit_log_format(ab, "<too long>");
1401 audit_log_untrustedstring(ab, p);
1406 * audit_log_end - end one audit record
1407 * @ab: the audit_buffer
1409 * The netlink_* functions cannot be called inside an irq context, so
1410 * the audit buffer is placed on a queue and a tasklet is scheduled to
1411 * remove them from the queue outside the irq context. May be called in
1414 void audit_log_end(struct audit_buffer *ab)
1418 if (!audit_rate_check()) {
1419 audit_log_lost("rate limit exceeded");
1421 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1422 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1425 skb_queue_tail(&audit_skb_queue, ab->skb);
1426 wake_up_interruptible(&kauditd_wait);
1428 if (nlh->nlmsg_type != AUDIT_EOE) {
1429 if (printk_ratelimit()) {
1430 printk(KERN_NOTICE "type=%d %s\n",
1432 ab->skb->data + NLMSG_SPACE(0));
1434 audit_log_lost("printk limit exceeded\n");
1436 audit_hold_skb(ab->skb);
1440 audit_buffer_free(ab);
1444 * audit_log - Log an audit record
1445 * @ctx: audit context
1446 * @gfp_mask: type of allocation
1447 * @type: audit message type
1448 * @fmt: format string to use
1449 * @...: variable parameters matching the format string
1451 * This is a convenience function that calls audit_log_start,
1452 * audit_log_vformat, and audit_log_end. It may be called
1455 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1456 const char *fmt, ...)
1458 struct audit_buffer *ab;
1461 ab = audit_log_start(ctx, gfp_mask, type);
1463 va_start(args, fmt);
1464 audit_log_vformat(ab, fmt, args);
1470 EXPORT_SYMBOL(audit_log_start);
1471 EXPORT_SYMBOL(audit_log_end);
1472 EXPORT_SYMBOL(audit_log_format);
1473 EXPORT_SYMBOL(audit_log);