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 static struct task_struct *kauditd_task;
130 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
131 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
133 /* Serialize requests from userspace. */
134 static DEFINE_MUTEX(audit_cmd_mutex);
136 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
137 * audit records. Since printk uses a 1024 byte buffer, this buffer
138 * should be at least that large. */
139 #define AUDIT_BUFSIZ 1024
141 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
142 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
143 #define AUDIT_MAXFREE (2*NR_CPUS)
145 /* The audit_buffer is used when formatting an audit record. The caller
146 * locks briefly to get the record off the freelist or to allocate the
147 * buffer, and locks briefly to send the buffer to the netlink layer or
148 * to place it on a transmit queue. Multiple audit_buffers can be in
149 * use simultaneously. */
150 struct audit_buffer {
151 struct list_head list;
152 struct sk_buff *skb; /* formatted skb ready to send */
153 struct audit_context *ctx; /* NULL or associated context */
157 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
160 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
161 nlh->nlmsg_pid = pid;
165 void audit_panic(const char *message)
167 switch (audit_failure)
169 case AUDIT_FAIL_SILENT:
171 case AUDIT_FAIL_PRINTK:
172 if (printk_ratelimit())
173 printk(KERN_ERR "audit: %s\n", message);
175 case AUDIT_FAIL_PANIC:
176 /* test audit_pid since printk is always losey, why bother? */
178 panic("audit: %s\n", message);
183 static inline int audit_rate_check(void)
185 static unsigned long last_check = 0;
186 static int messages = 0;
187 static DEFINE_SPINLOCK(lock);
190 unsigned long elapsed;
193 if (!audit_rate_limit) return 1;
195 spin_lock_irqsave(&lock, flags);
196 if (++messages < audit_rate_limit) {
200 elapsed = now - last_check;
207 spin_unlock_irqrestore(&lock, flags);
213 * audit_log_lost - conditionally log lost audit message event
214 * @message: the message stating reason for lost audit message
216 * Emit at least 1 message per second, even if audit_rate_check is
218 * Always increment the lost messages counter.
220 void audit_log_lost(const char *message)
222 static unsigned long last_msg = 0;
223 static DEFINE_SPINLOCK(lock);
228 atomic_inc(&audit_lost);
230 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
233 spin_lock_irqsave(&lock, flags);
235 if (now - last_msg > HZ) {
239 spin_unlock_irqrestore(&lock, flags);
243 if (printk_ratelimit())
245 "audit: audit_lost=%d audit_rate_limit=%d "
246 "audit_backlog_limit=%d\n",
247 atomic_read(&audit_lost),
249 audit_backlog_limit);
250 audit_panic(message);
254 static int audit_log_config_change(char *function_name, int new, int old,
255 uid_t loginuid, u32 sessionid, u32 sid,
258 struct audit_buffer *ab;
261 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
262 audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
263 old, loginuid, sessionid);
268 rc = security_secid_to_secctx(sid, &ctx, &len);
270 audit_log_format(ab, " sid=%u", sid);
271 allow_changes = 0; /* Something weird, deny request */
273 audit_log_format(ab, " subj=%s", ctx);
274 security_release_secctx(ctx, len);
277 audit_log_format(ab, " res=%d", allow_changes);
282 static int audit_do_config_change(char *function_name, int *to_change,
283 int new, uid_t loginuid, u32 sessionid,
286 int allow_changes, rc = 0, old = *to_change;
288 /* check if we are locked */
289 if (audit_enabled == AUDIT_LOCKED)
294 if (audit_enabled != AUDIT_OFF) {
295 rc = audit_log_config_change(function_name, new, old, loginuid,
296 sessionid, sid, allow_changes);
301 /* If we are allowed, make the change */
302 if (allow_changes == 1)
304 /* Not allowed, update reason */
310 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
313 return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
314 limit, loginuid, sessionid, sid);
317 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
320 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
321 limit, loginuid, sessionid, sid);
324 static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
327 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
330 rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
331 loginuid, sessionid, sid);
334 audit_ever_enabled |= !!state;
339 static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
341 if (state != AUDIT_FAIL_SILENT
342 && state != AUDIT_FAIL_PRINTK
343 && state != AUDIT_FAIL_PANIC)
346 return audit_do_config_change("audit_failure", &audit_failure, state,
347 loginuid, sessionid, sid);
350 static int kauditd_thread(void *dummy)
355 while (!kthread_should_stop()) {
356 skb = skb_dequeue(&audit_skb_queue);
357 wake_up(&audit_backlog_wait);
360 int err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
362 BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
363 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
364 audit_log_lost("auditd dissapeared\n");
368 if (printk_ratelimit())
369 printk(KERN_NOTICE "%s\n", skb->data +
372 audit_log_lost("printk limit exceeded\n");
376 DECLARE_WAITQUEUE(wait, current);
377 set_current_state(TASK_INTERRUPTIBLE);
378 add_wait_queue(&kauditd_wait, &wait);
380 if (!skb_queue_len(&audit_skb_queue)) {
385 __set_current_state(TASK_RUNNING);
386 remove_wait_queue(&kauditd_wait, &wait);
392 static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
394 struct task_struct *tsk;
397 read_lock(&tasklist_lock);
398 tsk = find_task_by_pid(pid);
404 spin_lock_irq(&tsk->sighand->siglock);
405 if (!tsk->signal->audit_tty)
407 spin_unlock_irq(&tsk->sighand->siglock);
411 tty_audit_push_task(tsk, loginuid, sessionid);
413 read_unlock(&tasklist_lock);
417 int audit_send_list(void *_dest)
419 struct audit_netlink_list *dest = _dest;
423 /* wait for parent to finish and send an ACK */
424 mutex_lock(&audit_cmd_mutex);
425 mutex_unlock(&audit_cmd_mutex);
427 while ((skb = __skb_dequeue(&dest->q)) != NULL)
428 netlink_unicast(audit_sock, skb, pid, 0);
435 #ifdef CONFIG_AUDIT_TREE
436 static int prune_tree_thread(void *unused)
438 mutex_lock(&audit_cmd_mutex);
440 mutex_unlock(&audit_cmd_mutex);
444 void audit_schedule_prune(void)
446 kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
450 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
451 int multi, void *payload, int size)
454 struct nlmsghdr *nlh;
455 int len = NLMSG_SPACE(size);
457 int flags = multi ? NLM_F_MULTI : 0;
458 int t = done ? NLMSG_DONE : type;
460 skb = alloc_skb(len, GFP_KERNEL);
464 nlh = NLMSG_PUT(skb, pid, seq, t, size);
465 nlh->nlmsg_flags = flags;
466 data = NLMSG_DATA(nlh);
467 memcpy(data, payload, size);
470 nlmsg_failure: /* Used by NLMSG_PUT */
477 * audit_send_reply - send an audit reply message via netlink
478 * @pid: process id to send reply to
479 * @seq: sequence number
480 * @type: audit message type
481 * @done: done (last) flag
482 * @multi: multi-part message flag
483 * @payload: payload data
484 * @size: payload size
486 * Allocates an skb, builds the netlink message, and sends it to the pid.
487 * No failure notifications.
489 void audit_send_reply(int pid, int seq, int type, int done, int multi,
490 void *payload, int size)
493 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
496 /* Ignore failure. It'll only happen if the sender goes away,
497 because our timeout is set to infinite. */
498 netlink_unicast(audit_sock, skb, pid, 0);
503 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
506 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
513 case AUDIT_LIST_RULES:
519 case AUDIT_SIGNAL_INFO:
523 case AUDIT_MAKE_EQUIV:
524 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
528 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
529 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
530 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
533 default: /* bad msg */
540 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
541 u32 pid, u32 uid, uid_t auid, u32 ses,
548 if (!audit_enabled) {
553 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
554 audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u",
555 pid, uid, auid, ses);
557 rc = security_secid_to_secctx(sid, &ctx, &len);
559 audit_log_format(*ab, " ssid=%u", sid);
561 audit_log_format(*ab, " subj=%s", ctx);
562 security_release_secctx(ctx, len);
569 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
571 u32 uid, pid, seq, sid;
573 struct audit_status *status_get, status_set;
575 struct audit_buffer *ab;
576 u16 msg_type = nlh->nlmsg_type;
577 uid_t loginuid; /* loginuid of sender */
579 struct audit_sig_info *sig_data;
583 err = audit_netlink_ok(skb, msg_type);
587 /* As soon as there's any sign of userspace auditd,
588 * start kauditd to talk to it */
590 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
591 if (IS_ERR(kauditd_task)) {
592 err = PTR_ERR(kauditd_task);
597 pid = NETLINK_CREDS(skb)->pid;
598 uid = NETLINK_CREDS(skb)->uid;
599 loginuid = NETLINK_CB(skb).loginuid;
600 sessionid = NETLINK_CB(skb).sessionid;
601 sid = NETLINK_CB(skb).sid;
602 seq = nlh->nlmsg_seq;
603 data = NLMSG_DATA(nlh);
607 status_set.enabled = audit_enabled;
608 status_set.failure = audit_failure;
609 status_set.pid = audit_pid;
610 status_set.rate_limit = audit_rate_limit;
611 status_set.backlog_limit = audit_backlog_limit;
612 status_set.lost = atomic_read(&audit_lost);
613 status_set.backlog = skb_queue_len(&audit_skb_queue);
614 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
615 &status_set, sizeof(status_set));
618 if (nlh->nlmsg_len < sizeof(struct audit_status))
620 status_get = (struct audit_status *)data;
621 if (status_get->mask & AUDIT_STATUS_ENABLED) {
622 err = audit_set_enabled(status_get->enabled,
623 loginuid, sessionid, sid);
624 if (err < 0) return err;
626 if (status_get->mask & AUDIT_STATUS_FAILURE) {
627 err = audit_set_failure(status_get->failure,
628 loginuid, sessionid, sid);
629 if (err < 0) return err;
631 if (status_get->mask & AUDIT_STATUS_PID) {
632 int new_pid = status_get->pid;
634 if (audit_enabled != AUDIT_OFF)
635 audit_log_config_change("audit_pid", new_pid,
640 audit_nlk_pid = NETLINK_CB(skb).pid;
642 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
643 err = audit_set_rate_limit(status_get->rate_limit,
644 loginuid, sessionid, sid);
645 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
646 err = audit_set_backlog_limit(status_get->backlog_limit,
647 loginuid, sessionid, sid);
650 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
651 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
652 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
655 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
658 if (msg_type == AUDIT_USER_TTY) {
659 err = audit_prepare_user_tty(pid, loginuid,
664 audit_log_common_recv_msg(&ab, msg_type, pid, uid,
665 loginuid, sessionid, sid);
667 if (msg_type != AUDIT_USER_TTY)
668 audit_log_format(ab, " msg='%.1024s'",
673 audit_log_format(ab, " msg=");
674 size = nlmsg_len(nlh);
675 audit_log_n_untrustedstring(ab, size,
678 audit_set_pid(ab, pid);
684 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
686 if (audit_enabled == AUDIT_LOCKED) {
687 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
688 uid, loginuid, sessionid, sid);
690 audit_log_format(ab, " audit_enabled=%d res=0",
697 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
698 uid, seq, data, nlmsg_len(nlh),
699 loginuid, sessionid, sid);
703 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
705 if (audit_enabled == AUDIT_LOCKED) {
706 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
707 uid, loginuid, sessionid, sid);
709 audit_log_format(ab, " audit_enabled=%d res=0",
715 case AUDIT_LIST_RULES:
716 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
717 uid, seq, data, nlmsg_len(nlh),
718 loginuid, sessionid, sid);
723 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
724 uid, loginuid, sessionid, sid);
726 audit_log_format(ab, " op=trim res=1");
729 case AUDIT_MAKE_EQUIV: {
732 size_t len = nlmsg_len(nlh);
736 if (len < 2 * sizeof(u32))
738 memcpy(sizes, bufp, 2 * sizeof(u32));
739 bufp += 2 * sizeof(u32);
740 len -= 2 * sizeof(u32);
741 old = audit_unpack_string(&bufp, &len, sizes[0]);
746 new = audit_unpack_string(&bufp, &len, sizes[1]);
752 /* OK, here comes... */
753 err = audit_tag_tree(old, new);
755 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
756 uid, loginuid, sessionid, sid);
758 audit_log_format(ab, " op=make_equiv old=");
759 audit_log_untrustedstring(ab, old);
760 audit_log_format(ab, " new=");
761 audit_log_untrustedstring(ab, new);
762 audit_log_format(ab, " res=%d", !err);
768 case AUDIT_SIGNAL_INFO:
769 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
772 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
774 security_release_secctx(ctx, len);
777 sig_data->uid = audit_sig_uid;
778 sig_data->pid = audit_sig_pid;
779 memcpy(sig_data->ctx, ctx, len);
780 security_release_secctx(ctx, len);
781 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
782 0, 0, sig_data, sizeof(*sig_data) + len);
785 case AUDIT_TTY_GET: {
786 struct audit_tty_status s;
787 struct task_struct *tsk;
789 read_lock(&tasklist_lock);
790 tsk = find_task_by_pid(pid);
794 spin_lock_irq(&tsk->sighand->siglock);
795 s.enabled = tsk->signal->audit_tty != 0;
796 spin_unlock_irq(&tsk->sighand->siglock);
798 read_unlock(&tasklist_lock);
799 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0,
803 case AUDIT_TTY_SET: {
804 struct audit_tty_status *s;
805 struct task_struct *tsk;
807 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
810 if (s->enabled != 0 && s->enabled != 1)
812 read_lock(&tasklist_lock);
813 tsk = find_task_by_pid(pid);
817 spin_lock_irq(&tsk->sighand->siglock);
818 tsk->signal->audit_tty = s->enabled != 0;
819 spin_unlock_irq(&tsk->sighand->siglock);
821 read_unlock(&tasklist_lock);
829 return err < 0 ? err : 0;
833 * Get message from skb (based on rtnetlink_rcv_skb). Each message is
834 * processed by audit_receive_msg. Malformed skbs with wrong length are
835 * discarded silently.
837 static void audit_receive_skb(struct sk_buff *skb)
840 struct nlmsghdr *nlh;
843 while (skb->len >= NLMSG_SPACE(0)) {
844 nlh = nlmsg_hdr(skb);
845 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
847 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
850 if ((err = audit_receive_msg(skb, nlh))) {
851 netlink_ack(skb, nlh, err);
852 } else if (nlh->nlmsg_flags & NLM_F_ACK)
853 netlink_ack(skb, nlh, 0);
858 /* Receive messages from netlink socket. */
859 static void audit_receive(struct sk_buff *skb)
861 mutex_lock(&audit_cmd_mutex);
862 audit_receive_skb(skb);
863 mutex_unlock(&audit_cmd_mutex);
866 #ifdef CONFIG_AUDITSYSCALL
867 static const struct inotify_operations audit_inotify_ops = {
868 .handle_event = audit_handle_ievent,
869 .destroy_watch = audit_free_parent,
873 /* Initialize audit support at boot time. */
874 static int __init audit_init(void)
878 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
879 audit_default ? "enabled" : "disabled");
880 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
881 audit_receive, NULL, THIS_MODULE);
883 audit_panic("cannot initialize netlink socket");
885 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
887 skb_queue_head_init(&audit_skb_queue);
888 audit_initialized = 1;
889 audit_enabled = audit_default;
890 audit_ever_enabled |= !!audit_default;
892 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
894 #ifdef CONFIG_AUDITSYSCALL
895 audit_ih = inotify_init(&audit_inotify_ops);
896 if (IS_ERR(audit_ih))
897 audit_panic("cannot initialize inotify handle");
900 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
901 INIT_LIST_HEAD(&audit_inode_hash[i]);
905 __initcall(audit_init);
907 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
908 static int __init audit_enable(char *str)
910 audit_default = !!simple_strtol(str, NULL, 0);
911 printk(KERN_INFO "audit: %s%s\n",
912 audit_default ? "enabled" : "disabled",
913 audit_initialized ? "" : " (after initialization)");
914 if (audit_initialized) {
915 audit_enabled = audit_default;
916 audit_ever_enabled |= !!audit_default;
921 __setup("audit=", audit_enable);
923 static void audit_buffer_free(struct audit_buffer *ab)
933 spin_lock_irqsave(&audit_freelist_lock, flags);
934 if (audit_freelist_count > AUDIT_MAXFREE)
937 audit_freelist_count++;
938 list_add(&ab->list, &audit_freelist);
940 spin_unlock_irqrestore(&audit_freelist_lock, flags);
943 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
944 gfp_t gfp_mask, int type)
947 struct audit_buffer *ab = NULL;
948 struct nlmsghdr *nlh;
950 spin_lock_irqsave(&audit_freelist_lock, flags);
951 if (!list_empty(&audit_freelist)) {
952 ab = list_entry(audit_freelist.next,
953 struct audit_buffer, list);
955 --audit_freelist_count;
957 spin_unlock_irqrestore(&audit_freelist_lock, flags);
960 ab = kmalloc(sizeof(*ab), gfp_mask);
965 ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
970 ab->gfp_mask = gfp_mask;
971 nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
972 nlh->nlmsg_type = type;
973 nlh->nlmsg_flags = 0;
978 audit_buffer_free(ab);
983 * audit_serial - compute a serial number for the audit record
985 * Compute a serial number for the audit record. Audit records are
986 * written to user-space as soon as they are generated, so a complete
987 * audit record may be written in several pieces. The timestamp of the
988 * record and this serial number are used by the user-space tools to
989 * determine which pieces belong to the same audit record. The
990 * (timestamp,serial) tuple is unique for each syscall and is live from
991 * syscall entry to syscall exit.
993 * NOTE: Another possibility is to store the formatted records off the
994 * audit context (for those records that have a context), and emit them
995 * all at syscall exit. However, this could delay the reporting of
996 * significant errors until syscall exit (or never, if the system
999 unsigned int audit_serial(void)
1001 static DEFINE_SPINLOCK(serial_lock);
1002 static unsigned int serial = 0;
1004 unsigned long flags;
1007 spin_lock_irqsave(&serial_lock, flags);
1010 } while (unlikely(!ret));
1011 spin_unlock_irqrestore(&serial_lock, flags);
1016 static inline void audit_get_stamp(struct audit_context *ctx,
1017 struct timespec *t, unsigned int *serial)
1020 auditsc_get_stamp(ctx, t, serial);
1023 *serial = audit_serial();
1027 /* Obtain an audit buffer. This routine does locking to obtain the
1028 * audit buffer, but then no locking is required for calls to
1029 * audit_log_*format. If the tsk is a task that is currently in a
1030 * syscall, then the syscall is marked as auditable and an audit record
1031 * will be written at syscall exit. If there is no associated task, tsk
1032 * should be NULL. */
1035 * audit_log_start - obtain an audit buffer
1036 * @ctx: audit_context (may be NULL)
1037 * @gfp_mask: type of allocation
1038 * @type: audit message type
1040 * Returns audit_buffer pointer on success or NULL on error.
1042 * Obtain an audit buffer. This routine does locking to obtain the
1043 * audit buffer, but then no locking is required for calls to
1044 * audit_log_*format. If the task (ctx) is a task that is currently in a
1045 * syscall, then the syscall is marked as auditable and an audit record
1046 * will be written at syscall exit. If there is no associated task, then
1047 * task context (ctx) should be NULL.
1049 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1052 struct audit_buffer *ab = NULL;
1054 unsigned int uninitialized_var(serial);
1056 unsigned long timeout_start = jiffies;
1058 if (!audit_initialized)
1061 if (unlikely(audit_filter_type(type)))
1064 if (gfp_mask & __GFP_WAIT)
1067 reserve = 5; /* Allow atomic callers to go up to five
1068 entries over the normal backlog limit */
1070 while (audit_backlog_limit
1071 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1072 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1073 && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1075 /* Wait for auditd to drain the queue a little */
1076 DECLARE_WAITQUEUE(wait, current);
1077 set_current_state(TASK_INTERRUPTIBLE);
1078 add_wait_queue(&audit_backlog_wait, &wait);
1080 if (audit_backlog_limit &&
1081 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1082 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1084 __set_current_state(TASK_RUNNING);
1085 remove_wait_queue(&audit_backlog_wait, &wait);
1088 if (audit_rate_check() && printk_ratelimit())
1090 "audit: audit_backlog=%d > "
1091 "audit_backlog_limit=%d\n",
1092 skb_queue_len(&audit_skb_queue),
1093 audit_backlog_limit);
1094 audit_log_lost("backlog limit exceeded");
1095 audit_backlog_wait_time = audit_backlog_wait_overflow;
1096 wake_up(&audit_backlog_wait);
1100 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1102 audit_log_lost("out of memory in audit_log_start");
1106 audit_get_stamp(ab->ctx, &t, &serial);
1108 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1109 t.tv_sec, t.tv_nsec/1000000, serial);
1114 * audit_expand - expand skb in the audit buffer
1116 * @extra: space to add at tail of the skb
1118 * Returns 0 (no space) on failed expansion, or available space if
1121 static inline int audit_expand(struct audit_buffer *ab, int extra)
1123 struct sk_buff *skb = ab->skb;
1124 int oldtail = skb_tailroom(skb);
1125 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1126 int newtail = skb_tailroom(skb);
1129 audit_log_lost("out of memory in audit_expand");
1133 skb->truesize += newtail - oldtail;
1138 * Format an audit message into the audit buffer. If there isn't enough
1139 * room in the audit buffer, more room will be allocated and vsnprint
1140 * will be called a second time. Currently, we assume that a printk
1141 * can't format message larger than 1024 bytes, so we don't either.
1143 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1147 struct sk_buff *skb;
1155 avail = skb_tailroom(skb);
1157 avail = audit_expand(ab, AUDIT_BUFSIZ);
1161 va_copy(args2, args);
1162 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1164 /* The printk buffer is 1024 bytes long, so if we get
1165 * here and AUDIT_BUFSIZ is at least 1024, then we can
1166 * log everything that printk could have logged. */
1167 avail = audit_expand(ab,
1168 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1171 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1181 * audit_log_format - format a message into the audit buffer.
1183 * @fmt: format string
1184 * @...: optional parameters matching @fmt string
1186 * All the work is done in audit_log_vformat.
1188 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1194 va_start(args, fmt);
1195 audit_log_vformat(ab, fmt, args);
1200 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1201 * @ab: the audit_buffer
1202 * @buf: buffer to convert to hex
1203 * @len: length of @buf to be converted
1205 * No return value; failure to expand is silently ignored.
1207 * This function will take the passed buf and convert it into a string of
1208 * ascii hex digits. The new string is placed onto the skb.
1210 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1213 int i, avail, new_len;
1215 struct sk_buff *skb;
1216 static const unsigned char *hex = "0123456789ABCDEF";
1223 avail = skb_tailroom(skb);
1225 if (new_len >= avail) {
1226 /* Round the buffer request up to the next multiple */
1227 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1228 avail = audit_expand(ab, new_len);
1233 ptr = skb_tail_pointer(skb);
1234 for (i=0; i<len; i++) {
1235 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1236 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1239 skb_put(skb, len << 1); /* new string is twice the old string */
1243 * Format a string of no more than slen characters into the audit buffer,
1244 * enclosed in quote marks.
1246 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1251 struct sk_buff *skb;
1258 avail = skb_tailroom(skb);
1259 new_len = slen + 3; /* enclosing quotes + null terminator */
1260 if (new_len > avail) {
1261 avail = audit_expand(ab, new_len);
1265 ptr = skb_tail_pointer(skb);
1267 memcpy(ptr, string, slen);
1271 skb_put(skb, slen + 2); /* don't include null terminator */
1275 * audit_string_contains_control - does a string need to be logged in hex
1276 * @string: string to be checked
1277 * @len: max length of the string to check
1279 int audit_string_contains_control(const char *string, size_t len)
1281 const unsigned char *p;
1282 for (p = string; p < (const unsigned char *)string + len && *p; p++) {
1283 if (*p == '"' || *p < 0x21 || *p > 0x7f)
1290 * audit_log_n_untrustedstring - log a string that may contain random characters
1292 * @len: length of string (not including trailing null)
1293 * @string: string to be logged
1295 * This code will escape a string that is passed to it if the string
1296 * contains a control character, unprintable character, double quote mark,
1297 * or a space. Unescaped strings will start and end with a double quote mark.
1298 * Strings that are escaped are printed in hex (2 digits per char).
1300 * The caller specifies the number of characters in the string to log, which may
1301 * or may not be the entire string.
1303 void audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1306 if (audit_string_contains_control(string, len))
1307 audit_log_hex(ab, string, len);
1309 audit_log_n_string(ab, len, string);
1313 * audit_log_untrustedstring - log a string that may contain random characters
1315 * @string: string to be logged
1317 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1318 * determine string length.
1320 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1322 audit_log_n_untrustedstring(ab, strlen(string), string);
1325 /* This is a helper-function to print the escaped d_path */
1326 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1332 audit_log_format(ab, " %s", prefix);
1334 /* We will allow 11 spaces for ' (deleted)' to be appended */
1335 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1337 audit_log_format(ab, "<no memory>");
1340 p = d_path(path, pathname, PATH_MAX+11);
1341 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1342 /* FIXME: can we save some information here? */
1343 audit_log_format(ab, "<too long>");
1345 audit_log_untrustedstring(ab, p);
1350 * audit_log_end - end one audit record
1351 * @ab: the audit_buffer
1353 * The netlink_* functions cannot be called inside an irq context, so
1354 * the audit buffer is placed on a queue and a tasklet is scheduled to
1355 * remove them from the queue outside the irq context. May be called in
1358 void audit_log_end(struct audit_buffer *ab)
1362 if (!audit_rate_check()) {
1363 audit_log_lost("rate limit exceeded");
1365 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1367 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1368 skb_queue_tail(&audit_skb_queue, ab->skb);
1370 wake_up_interruptible(&kauditd_wait);
1371 } else if (nlh->nlmsg_type != AUDIT_EOE) {
1372 if (printk_ratelimit()) {
1373 printk(KERN_NOTICE "type=%d %s\n",
1375 ab->skb->data + NLMSG_SPACE(0));
1377 audit_log_lost("printk limit exceeded\n");
1380 audit_buffer_free(ab);
1384 * audit_log - Log an audit record
1385 * @ctx: audit context
1386 * @gfp_mask: type of allocation
1387 * @type: audit message type
1388 * @fmt: format string to use
1389 * @...: variable parameters matching the format string
1391 * This is a convenience function that calls audit_log_start,
1392 * audit_log_vformat, and audit_log_end. It may be called
1395 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1396 const char *fmt, ...)
1398 struct audit_buffer *ab;
1401 ab = audit_log_start(ctx, gfp_mask, type);
1403 va_start(args, fmt);
1404 audit_log_vformat(ab, fmt, args);
1410 EXPORT_SYMBOL(audit_log_start);
1411 EXPORT_SYMBOL(audit_log_end);
1412 EXPORT_SYMBOL(audit_log_format);
1413 EXPORT_SYMBOL(audit_log);