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 SELinux.
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/selinux.h>
59 #include <linux/inotify.h>
60 #include <linux/freezer.h>
61 #include <linux/tty.h>
65 /* No auditing will take place until audit_initialized != 0.
66 * (Initialization happens after skb_init is called.) */
67 static int audit_initialized;
71 #define AUDIT_LOCKED 2
73 int audit_ever_enabled;
75 /* Default state when kernel boots without any parameters. */
76 static int audit_default;
78 /* If auditing cannot proceed, audit_failure selects what happens. */
79 static int audit_failure = AUDIT_FAIL_PRINTK;
82 * If audit records are to be written to the netlink socket, audit_pid
83 * contains the pid of the auditd process and audit_nlk_pid contains
84 * the pid to use to send netlink messages to that process.
87 static int audit_nlk_pid;
89 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
90 * to that number per second. This prevents DoS attacks, but results in
91 * audit records being dropped. */
92 static int audit_rate_limit;
94 /* Number of outstanding audit_buffers allowed. */
95 static int audit_backlog_limit = 64;
96 static int audit_backlog_wait_time = 60 * HZ;
97 static int audit_backlog_wait_overflow = 0;
99 /* The identity of the user shutting down the audit system. */
100 uid_t audit_sig_uid = -1;
101 pid_t audit_sig_pid = -1;
102 u32 audit_sig_sid = 0;
104 /* Records can be lost in several ways:
105 0) [suppressed in audit_alloc]
106 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
107 2) out of memory in audit_log_move [alloc_skb]
108 3) suppressed due to audit_rate_limit
109 4) suppressed due to audit_backlog_limit
111 static atomic_t audit_lost = ATOMIC_INIT(0);
113 /* The netlink socket. */
114 static struct sock *audit_sock;
116 /* Inotify handle. */
117 struct inotify_handle *audit_ih;
119 /* Hash for inode-based rules */
120 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
122 /* The audit_freelist is a list of pre-allocated audit buffers (if more
123 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
124 * being placed on the freelist). */
125 static DEFINE_SPINLOCK(audit_freelist_lock);
126 static int audit_freelist_count;
127 static LIST_HEAD(audit_freelist);
129 static struct sk_buff_head audit_skb_queue;
130 static struct task_struct *kauditd_task;
131 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
132 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
134 /* Serialize requests from userspace. */
135 static DEFINE_MUTEX(audit_cmd_mutex);
137 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
138 * audit records. Since printk uses a 1024 byte buffer, this buffer
139 * should be at least that large. */
140 #define AUDIT_BUFSIZ 1024
142 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
143 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
144 #define AUDIT_MAXFREE (2*NR_CPUS)
146 /* The audit_buffer is used when formatting an audit record. The caller
147 * locks briefly to get the record off the freelist or to allocate the
148 * buffer, and locks briefly to send the buffer to the netlink layer or
149 * to place it on a transmit queue. Multiple audit_buffers can be in
150 * use simultaneously. */
151 struct audit_buffer {
152 struct list_head list;
153 struct sk_buff *skb; /* formatted skb ready to send */
154 struct audit_context *ctx; /* NULL or associated context */
158 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
161 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
162 nlh->nlmsg_pid = pid;
166 void audit_panic(const char *message)
168 switch (audit_failure)
170 case AUDIT_FAIL_SILENT:
172 case AUDIT_FAIL_PRINTK:
173 if (printk_ratelimit())
174 printk(KERN_ERR "audit: %s\n", message);
176 case AUDIT_FAIL_PANIC:
177 /* test audit_pid since printk is always losey, why bother? */
179 panic("audit: %s\n", message);
184 static inline int audit_rate_check(void)
186 static unsigned long last_check = 0;
187 static int messages = 0;
188 static DEFINE_SPINLOCK(lock);
191 unsigned long elapsed;
194 if (!audit_rate_limit) return 1;
196 spin_lock_irqsave(&lock, flags);
197 if (++messages < audit_rate_limit) {
201 elapsed = now - last_check;
208 spin_unlock_irqrestore(&lock, flags);
214 * audit_log_lost - conditionally log lost audit message event
215 * @message: the message stating reason for lost audit message
217 * Emit at least 1 message per second, even if audit_rate_check is
219 * Always increment the lost messages counter.
221 void audit_log_lost(const char *message)
223 static unsigned long last_msg = 0;
224 static DEFINE_SPINLOCK(lock);
229 atomic_inc(&audit_lost);
231 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
234 spin_lock_irqsave(&lock, flags);
236 if (now - last_msg > HZ) {
240 spin_unlock_irqrestore(&lock, flags);
244 if (printk_ratelimit())
246 "audit: audit_lost=%d audit_rate_limit=%d "
247 "audit_backlog_limit=%d\n",
248 atomic_read(&audit_lost),
250 audit_backlog_limit);
251 audit_panic(message);
255 static int audit_log_config_change(char *function_name, int new, int old,
256 uid_t loginuid, u32 sid, int allow_changes)
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 by auid=%u", function_name, new,
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 sid)
285 int allow_changes, rc = 0, old = *to_change;
287 /* check if we are locked */
288 if (audit_enabled == AUDIT_LOCKED)
293 if (audit_enabled != AUDIT_OFF) {
294 rc = audit_log_config_change(function_name, new, old,
295 loginuid, sid, allow_changes);
300 /* If we are allowed, make the change */
301 if (allow_changes == 1)
303 /* Not allowed, update reason */
309 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
311 return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
312 limit, loginuid, sid);
315 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
317 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
318 limit, loginuid, sid);
321 static int audit_set_enabled(int state, uid_t loginuid, u32 sid)
324 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
327 rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
331 audit_ever_enabled |= !!state;
336 static int audit_set_failure(int state, uid_t loginuid, u32 sid)
338 if (state != AUDIT_FAIL_SILENT
339 && state != AUDIT_FAIL_PRINTK
340 && state != AUDIT_FAIL_PANIC)
343 return audit_do_config_change("audit_failure", &audit_failure, state,
347 static int kauditd_thread(void *dummy)
352 while (!kthread_should_stop()) {
353 skb = skb_dequeue(&audit_skb_queue);
354 wake_up(&audit_backlog_wait);
357 int err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
359 BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
360 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
361 audit_log_lost("auditd dissapeared\n");
365 if (printk_ratelimit())
366 printk(KERN_NOTICE "%s\n", skb->data +
369 audit_log_lost("printk limit exceeded\n");
373 DECLARE_WAITQUEUE(wait, current);
374 set_current_state(TASK_INTERRUPTIBLE);
375 add_wait_queue(&kauditd_wait, &wait);
377 if (!skb_queue_len(&audit_skb_queue)) {
382 __set_current_state(TASK_RUNNING);
383 remove_wait_queue(&kauditd_wait, &wait);
389 static int audit_prepare_user_tty(pid_t pid, uid_t loginuid)
391 struct task_struct *tsk;
394 read_lock(&tasklist_lock);
395 tsk = find_task_by_pid(pid);
401 spin_lock_irq(&tsk->sighand->siglock);
402 if (!tsk->signal->audit_tty)
404 spin_unlock_irq(&tsk->sighand->siglock);
408 tty_audit_push_task(tsk, loginuid);
410 read_unlock(&tasklist_lock);
414 int audit_send_list(void *_dest)
416 struct audit_netlink_list *dest = _dest;
420 /* wait for parent to finish and send an ACK */
421 mutex_lock(&audit_cmd_mutex);
422 mutex_unlock(&audit_cmd_mutex);
424 while ((skb = __skb_dequeue(&dest->q)) != NULL)
425 netlink_unicast(audit_sock, skb, pid, 0);
432 #ifdef CONFIG_AUDIT_TREE
433 static int prune_tree_thread(void *unused)
435 mutex_lock(&audit_cmd_mutex);
437 mutex_unlock(&audit_cmd_mutex);
441 void audit_schedule_prune(void)
443 kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
447 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
448 int multi, void *payload, int size)
451 struct nlmsghdr *nlh;
452 int len = NLMSG_SPACE(size);
454 int flags = multi ? NLM_F_MULTI : 0;
455 int t = done ? NLMSG_DONE : type;
457 skb = alloc_skb(len, GFP_KERNEL);
461 nlh = NLMSG_PUT(skb, pid, seq, t, size);
462 nlh->nlmsg_flags = flags;
463 data = NLMSG_DATA(nlh);
464 memcpy(data, payload, size);
467 nlmsg_failure: /* Used by NLMSG_PUT */
474 * audit_send_reply - send an audit reply message via netlink
475 * @pid: process id to send reply to
476 * @seq: sequence number
477 * @type: audit message type
478 * @done: done (last) flag
479 * @multi: multi-part message flag
480 * @payload: payload data
481 * @size: payload size
483 * Allocates an skb, builds the netlink message, and sends it to the pid.
484 * No failure notifications.
486 void audit_send_reply(int pid, int seq, int type, int done, int multi,
487 void *payload, int size)
490 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
493 /* Ignore failure. It'll only happen if the sender goes away,
494 because our timeout is set to infinite. */
495 netlink_unicast(audit_sock, skb, pid, 0);
500 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
503 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
510 case AUDIT_LIST_RULES:
516 case AUDIT_SIGNAL_INFO:
520 case AUDIT_MAKE_EQUIV:
521 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
525 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
526 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
527 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
530 default: /* bad msg */
537 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
538 u32 pid, u32 uid, uid_t auid, u32 sid)
544 if (!audit_enabled) {
549 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
550 audit_log_format(*ab, "user pid=%d uid=%u auid=%u",
553 rc = security_secid_to_secctx(sid, &ctx, &len);
555 audit_log_format(*ab, " ssid=%u", sid);
557 audit_log_format(*ab, " subj=%s", ctx);
558 security_release_secctx(ctx, len);
565 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
567 u32 uid, pid, seq, sid;
569 struct audit_status *status_get, status_set;
571 struct audit_buffer *ab;
572 u16 msg_type = nlh->nlmsg_type;
573 uid_t loginuid; /* loginuid of sender */
574 struct audit_sig_info *sig_data;
578 err = audit_netlink_ok(skb, msg_type);
582 /* As soon as there's any sign of userspace auditd,
583 * start kauditd to talk to it */
585 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
586 if (IS_ERR(kauditd_task)) {
587 err = PTR_ERR(kauditd_task);
592 pid = NETLINK_CREDS(skb)->pid;
593 uid = NETLINK_CREDS(skb)->uid;
594 loginuid = NETLINK_CB(skb).loginuid;
595 sid = NETLINK_CB(skb).sid;
596 seq = nlh->nlmsg_seq;
597 data = NLMSG_DATA(nlh);
601 status_set.enabled = audit_enabled;
602 status_set.failure = audit_failure;
603 status_set.pid = audit_pid;
604 status_set.rate_limit = audit_rate_limit;
605 status_set.backlog_limit = audit_backlog_limit;
606 status_set.lost = atomic_read(&audit_lost);
607 status_set.backlog = skb_queue_len(&audit_skb_queue);
608 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
609 &status_set, sizeof(status_set));
612 if (nlh->nlmsg_len < sizeof(struct audit_status))
614 status_get = (struct audit_status *)data;
615 if (status_get->mask & AUDIT_STATUS_ENABLED) {
616 err = audit_set_enabled(status_get->enabled,
618 if (err < 0) return err;
620 if (status_get->mask & AUDIT_STATUS_FAILURE) {
621 err = audit_set_failure(status_get->failure,
623 if (err < 0) return err;
625 if (status_get->mask & AUDIT_STATUS_PID) {
626 int new_pid = status_get->pid;
628 if (audit_enabled != AUDIT_OFF)
629 audit_log_config_change("audit_pid", new_pid,
634 audit_nlk_pid = NETLINK_CB(skb).pid;
636 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
637 err = audit_set_rate_limit(status_get->rate_limit,
639 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
640 err = audit_set_backlog_limit(status_get->backlog_limit,
644 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
645 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
646 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
649 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
652 if (msg_type == AUDIT_USER_TTY) {
653 err = audit_prepare_user_tty(pid, loginuid);
657 audit_log_common_recv_msg(&ab, msg_type, pid, uid,
660 if (msg_type != AUDIT_USER_TTY)
661 audit_log_format(ab, " msg='%.1024s'",
666 audit_log_format(ab, " msg=");
667 size = nlmsg_len(nlh);
668 audit_log_n_untrustedstring(ab, size,
671 audit_set_pid(ab, pid);
677 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
679 if (audit_enabled == AUDIT_LOCKED) {
680 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
683 audit_log_format(ab, " audit_enabled=%d res=0",
690 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
691 uid, seq, data, nlmsg_len(nlh),
696 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
698 if (audit_enabled == AUDIT_LOCKED) {
699 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
702 audit_log_format(ab, " audit_enabled=%d res=0",
708 case AUDIT_LIST_RULES:
709 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
710 uid, seq, data, nlmsg_len(nlh),
716 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
719 audit_log_format(ab, " op=trim res=1");
722 case AUDIT_MAKE_EQUIV: {
725 size_t len = nlmsg_len(nlh);
729 if (len < 2 * sizeof(u32))
731 memcpy(sizes, bufp, 2 * sizeof(u32));
732 bufp += 2 * sizeof(u32);
733 len -= 2 * sizeof(u32);
734 old = audit_unpack_string(&bufp, &len, sizes[0]);
739 new = audit_unpack_string(&bufp, &len, sizes[1]);
745 /* OK, here comes... */
746 err = audit_tag_tree(old, new);
748 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
751 audit_log_format(ab, " op=make_equiv old=");
752 audit_log_untrustedstring(ab, old);
753 audit_log_format(ab, " new=");
754 audit_log_untrustedstring(ab, new);
755 audit_log_format(ab, " res=%d", !err);
761 case AUDIT_SIGNAL_INFO:
762 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
765 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
767 security_release_secctx(ctx, len);
770 sig_data->uid = audit_sig_uid;
771 sig_data->pid = audit_sig_pid;
772 memcpy(sig_data->ctx, ctx, len);
773 security_release_secctx(ctx, len);
774 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
775 0, 0, sig_data, sizeof(*sig_data) + len);
778 case AUDIT_TTY_GET: {
779 struct audit_tty_status s;
780 struct task_struct *tsk;
782 read_lock(&tasklist_lock);
783 tsk = find_task_by_pid(pid);
787 spin_lock_irq(&tsk->sighand->siglock);
788 s.enabled = tsk->signal->audit_tty != 0;
789 spin_unlock_irq(&tsk->sighand->siglock);
791 read_unlock(&tasklist_lock);
792 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0,
796 case AUDIT_TTY_SET: {
797 struct audit_tty_status *s;
798 struct task_struct *tsk;
800 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
803 if (s->enabled != 0 && s->enabled != 1)
805 read_lock(&tasklist_lock);
806 tsk = find_task_by_pid(pid);
810 spin_lock_irq(&tsk->sighand->siglock);
811 tsk->signal->audit_tty = s->enabled != 0;
812 spin_unlock_irq(&tsk->sighand->siglock);
814 read_unlock(&tasklist_lock);
822 return err < 0 ? err : 0;
826 * Get message from skb (based on rtnetlink_rcv_skb). Each message is
827 * processed by audit_receive_msg. Malformed skbs with wrong length are
828 * discarded silently.
830 static void audit_receive_skb(struct sk_buff *skb)
833 struct nlmsghdr *nlh;
836 while (skb->len >= NLMSG_SPACE(0)) {
837 nlh = nlmsg_hdr(skb);
838 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
840 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
843 if ((err = audit_receive_msg(skb, nlh))) {
844 netlink_ack(skb, nlh, err);
845 } else if (nlh->nlmsg_flags & NLM_F_ACK)
846 netlink_ack(skb, nlh, 0);
851 /* Receive messages from netlink socket. */
852 static void audit_receive(struct sk_buff *skb)
854 mutex_lock(&audit_cmd_mutex);
855 audit_receive_skb(skb);
856 mutex_unlock(&audit_cmd_mutex);
859 #ifdef CONFIG_AUDITSYSCALL
860 static const struct inotify_operations audit_inotify_ops = {
861 .handle_event = audit_handle_ievent,
862 .destroy_watch = audit_free_parent,
866 /* Initialize audit support at boot time. */
867 static int __init audit_init(void)
871 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
872 audit_default ? "enabled" : "disabled");
873 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
874 audit_receive, NULL, THIS_MODULE);
876 audit_panic("cannot initialize netlink socket");
878 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
880 skb_queue_head_init(&audit_skb_queue);
881 audit_initialized = 1;
882 audit_enabled = audit_default;
883 audit_ever_enabled |= !!audit_default;
885 /* Register the callback with selinux. This callback will be invoked
886 * when a new policy is loaded. */
887 selinux_audit_set_callback(&selinux_audit_rule_update);
889 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
891 #ifdef CONFIG_AUDITSYSCALL
892 audit_ih = inotify_init(&audit_inotify_ops);
893 if (IS_ERR(audit_ih))
894 audit_panic("cannot initialize inotify handle");
897 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
898 INIT_LIST_HEAD(&audit_inode_hash[i]);
902 __initcall(audit_init);
904 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
905 static int __init audit_enable(char *str)
907 audit_default = !!simple_strtol(str, NULL, 0);
908 printk(KERN_INFO "audit: %s%s\n",
909 audit_default ? "enabled" : "disabled",
910 audit_initialized ? "" : " (after initialization)");
911 if (audit_initialized) {
912 audit_enabled = audit_default;
913 audit_ever_enabled |= !!audit_default;
918 __setup("audit=", audit_enable);
920 static void audit_buffer_free(struct audit_buffer *ab)
930 spin_lock_irqsave(&audit_freelist_lock, flags);
931 if (audit_freelist_count > AUDIT_MAXFREE)
934 audit_freelist_count++;
935 list_add(&ab->list, &audit_freelist);
937 spin_unlock_irqrestore(&audit_freelist_lock, flags);
940 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
941 gfp_t gfp_mask, int type)
944 struct audit_buffer *ab = NULL;
945 struct nlmsghdr *nlh;
947 spin_lock_irqsave(&audit_freelist_lock, flags);
948 if (!list_empty(&audit_freelist)) {
949 ab = list_entry(audit_freelist.next,
950 struct audit_buffer, list);
952 --audit_freelist_count;
954 spin_unlock_irqrestore(&audit_freelist_lock, flags);
957 ab = kmalloc(sizeof(*ab), gfp_mask);
962 ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
967 ab->gfp_mask = gfp_mask;
968 nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
969 nlh->nlmsg_type = type;
970 nlh->nlmsg_flags = 0;
975 audit_buffer_free(ab);
980 * audit_serial - compute a serial number for the audit record
982 * Compute a serial number for the audit record. Audit records are
983 * written to user-space as soon as they are generated, so a complete
984 * audit record may be written in several pieces. The timestamp of the
985 * record and this serial number are used by the user-space tools to
986 * determine which pieces belong to the same audit record. The
987 * (timestamp,serial) tuple is unique for each syscall and is live from
988 * syscall entry to syscall exit.
990 * NOTE: Another possibility is to store the formatted records off the
991 * audit context (for those records that have a context), and emit them
992 * all at syscall exit. However, this could delay the reporting of
993 * significant errors until syscall exit (or never, if the system
996 unsigned int audit_serial(void)
998 static DEFINE_SPINLOCK(serial_lock);
999 static unsigned int serial = 0;
1001 unsigned long flags;
1004 spin_lock_irqsave(&serial_lock, flags);
1007 } while (unlikely(!ret));
1008 spin_unlock_irqrestore(&serial_lock, flags);
1013 static inline void audit_get_stamp(struct audit_context *ctx,
1014 struct timespec *t, unsigned int *serial)
1017 auditsc_get_stamp(ctx, t, serial);
1020 *serial = audit_serial();
1024 /* Obtain an audit buffer. This routine does locking to obtain the
1025 * audit buffer, but then no locking is required for calls to
1026 * audit_log_*format. If the tsk is a task that is currently in a
1027 * syscall, then the syscall is marked as auditable and an audit record
1028 * will be written at syscall exit. If there is no associated task, tsk
1029 * should be NULL. */
1032 * audit_log_start - obtain an audit buffer
1033 * @ctx: audit_context (may be NULL)
1034 * @gfp_mask: type of allocation
1035 * @type: audit message type
1037 * Returns audit_buffer pointer on success or NULL on error.
1039 * Obtain an audit buffer. This routine does locking to obtain the
1040 * audit buffer, but then no locking is required for calls to
1041 * audit_log_*format. If the task (ctx) is a task that is currently in a
1042 * syscall, then the syscall is marked as auditable and an audit record
1043 * will be written at syscall exit. If there is no associated task, then
1044 * task context (ctx) should be NULL.
1046 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1049 struct audit_buffer *ab = NULL;
1051 unsigned int uninitialized_var(serial);
1053 unsigned long timeout_start = jiffies;
1055 if (!audit_initialized)
1058 if (unlikely(audit_filter_type(type)))
1061 if (gfp_mask & __GFP_WAIT)
1064 reserve = 5; /* Allow atomic callers to go up to five
1065 entries over the normal backlog limit */
1067 while (audit_backlog_limit
1068 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1069 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1070 && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1072 /* Wait for auditd to drain the queue a little */
1073 DECLARE_WAITQUEUE(wait, current);
1074 set_current_state(TASK_INTERRUPTIBLE);
1075 add_wait_queue(&audit_backlog_wait, &wait);
1077 if (audit_backlog_limit &&
1078 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1079 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1081 __set_current_state(TASK_RUNNING);
1082 remove_wait_queue(&audit_backlog_wait, &wait);
1085 if (audit_rate_check() && printk_ratelimit())
1087 "audit: audit_backlog=%d > "
1088 "audit_backlog_limit=%d\n",
1089 skb_queue_len(&audit_skb_queue),
1090 audit_backlog_limit);
1091 audit_log_lost("backlog limit exceeded");
1092 audit_backlog_wait_time = audit_backlog_wait_overflow;
1093 wake_up(&audit_backlog_wait);
1097 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1099 audit_log_lost("out of memory in audit_log_start");
1103 audit_get_stamp(ab->ctx, &t, &serial);
1105 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1106 t.tv_sec, t.tv_nsec/1000000, serial);
1111 * audit_expand - expand skb in the audit buffer
1113 * @extra: space to add at tail of the skb
1115 * Returns 0 (no space) on failed expansion, or available space if
1118 static inline int audit_expand(struct audit_buffer *ab, int extra)
1120 struct sk_buff *skb = ab->skb;
1121 int oldtail = skb_tailroom(skb);
1122 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1123 int newtail = skb_tailroom(skb);
1126 audit_log_lost("out of memory in audit_expand");
1130 skb->truesize += newtail - oldtail;
1135 * Format an audit message into the audit buffer. If there isn't enough
1136 * room in the audit buffer, more room will be allocated and vsnprint
1137 * will be called a second time. Currently, we assume that a printk
1138 * can't format message larger than 1024 bytes, so we don't either.
1140 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1144 struct sk_buff *skb;
1152 avail = skb_tailroom(skb);
1154 avail = audit_expand(ab, AUDIT_BUFSIZ);
1158 va_copy(args2, args);
1159 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1161 /* The printk buffer is 1024 bytes long, so if we get
1162 * here and AUDIT_BUFSIZ is at least 1024, then we can
1163 * log everything that printk could have logged. */
1164 avail = audit_expand(ab,
1165 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1168 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1178 * audit_log_format - format a message into the audit buffer.
1180 * @fmt: format string
1181 * @...: optional parameters matching @fmt string
1183 * All the work is done in audit_log_vformat.
1185 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1191 va_start(args, fmt);
1192 audit_log_vformat(ab, fmt, args);
1197 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1198 * @ab: the audit_buffer
1199 * @buf: buffer to convert to hex
1200 * @len: length of @buf to be converted
1202 * No return value; failure to expand is silently ignored.
1204 * This function will take the passed buf and convert it into a string of
1205 * ascii hex digits. The new string is placed onto the skb.
1207 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1210 int i, avail, new_len;
1212 struct sk_buff *skb;
1213 static const unsigned char *hex = "0123456789ABCDEF";
1220 avail = skb_tailroom(skb);
1222 if (new_len >= avail) {
1223 /* Round the buffer request up to the next multiple */
1224 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1225 avail = audit_expand(ab, new_len);
1230 ptr = skb_tail_pointer(skb);
1231 for (i=0; i<len; i++) {
1232 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1233 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1236 skb_put(skb, len << 1); /* new string is twice the old string */
1240 * Format a string of no more than slen characters into the audit buffer,
1241 * enclosed in quote marks.
1243 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1248 struct sk_buff *skb;
1255 avail = skb_tailroom(skb);
1256 new_len = slen + 3; /* enclosing quotes + null terminator */
1257 if (new_len > avail) {
1258 avail = audit_expand(ab, new_len);
1262 ptr = skb_tail_pointer(skb);
1264 memcpy(ptr, string, slen);
1268 skb_put(skb, slen + 2); /* don't include null terminator */
1272 * audit_string_contains_control - does a string need to be logged in hex
1273 * @string: string to be checked
1274 * @len: max length of the string to check
1276 int audit_string_contains_control(const char *string, size_t len)
1278 const unsigned char *p;
1279 for (p = string; p < (const unsigned char *)string + len && *p; p++) {
1280 if (*p == '"' || *p < 0x21 || *p > 0x7f)
1287 * audit_log_n_untrustedstring - log a string that may contain random characters
1289 * @len: length of string (not including trailing null)
1290 * @string: string to be logged
1292 * This code will escape a string that is passed to it if the string
1293 * contains a control character, unprintable character, double quote mark,
1294 * or a space. Unescaped strings will start and end with a double quote mark.
1295 * Strings that are escaped are printed in hex (2 digits per char).
1297 * The caller specifies the number of characters in the string to log, which may
1298 * or may not be the entire string.
1300 void audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1303 if (audit_string_contains_control(string, len))
1304 audit_log_hex(ab, string, len);
1306 audit_log_n_string(ab, len, string);
1310 * audit_log_untrustedstring - log a string that may contain random characters
1312 * @string: string to be logged
1314 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1315 * determine string length.
1317 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1319 audit_log_n_untrustedstring(ab, strlen(string), string);
1322 /* This is a helper-function to print the escaped d_path */
1323 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1329 audit_log_format(ab, " %s", prefix);
1331 /* We will allow 11 spaces for ' (deleted)' to be appended */
1332 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1334 audit_log_format(ab, "<no memory>");
1337 p = d_path(path, pathname, PATH_MAX+11);
1338 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1339 /* FIXME: can we save some information here? */
1340 audit_log_format(ab, "<too long>");
1342 audit_log_untrustedstring(ab, p);
1347 * audit_log_end - end one audit record
1348 * @ab: the audit_buffer
1350 * The netlink_* functions cannot be called inside an irq context, so
1351 * the audit buffer is placed on a queue and a tasklet is scheduled to
1352 * remove them from the queue outside the irq context. May be called in
1355 void audit_log_end(struct audit_buffer *ab)
1359 if (!audit_rate_check()) {
1360 audit_log_lost("rate limit exceeded");
1362 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1364 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1365 skb_queue_tail(&audit_skb_queue, ab->skb);
1367 wake_up_interruptible(&kauditd_wait);
1368 } else if (nlh->nlmsg_type != AUDIT_EOE) {
1369 if (printk_ratelimit()) {
1370 printk(KERN_NOTICE "type=%d %s\n",
1372 ab->skb->data + NLMSG_SPACE(0));
1374 audit_log_lost("printk limit exceeded\n");
1377 audit_buffer_free(ab);
1381 * audit_log - Log an audit record
1382 * @ctx: audit context
1383 * @gfp_mask: type of allocation
1384 * @type: audit message type
1385 * @fmt: format string to use
1386 * @...: variable parameters matching the format string
1388 * This is a convenience function that calls audit_log_start,
1389 * audit_log_vformat, and audit_log_end. It may be called
1392 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1393 const char *fmt, ...)
1395 struct audit_buffer *ab;
1398 ab = audit_log_start(ctx, gfp_mask, type);
1400 va_start(args, fmt);
1401 audit_log_vformat(ab, fmt, args);
1407 EXPORT_SYMBOL(audit_log_start);
1408 EXPORT_SYMBOL(audit_log_end);
1409 EXPORT_SYMBOL(audit_log_format);
1410 EXPORT_SYMBOL(audit_log);