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
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;
80 /* If audit records are to be written to the netlink socket, audit_pid
81 * contains the (non-zero) pid. */
84 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
85 * to that number per second. This prevents DoS attacks, but results in
86 * audit records being dropped. */
87 static int audit_rate_limit;
89 /* Number of outstanding audit_buffers allowed. */
90 static int audit_backlog_limit = 64;
91 static int audit_backlog_wait_time = 60 * HZ;
92 static int audit_backlog_wait_overflow = 0;
94 /* The identity of the user shutting down the audit system. */
95 uid_t audit_sig_uid = -1;
96 pid_t audit_sig_pid = -1;
97 u32 audit_sig_sid = 0;
99 /* Records can be lost in several ways:
100 0) [suppressed in audit_alloc]
101 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
102 2) out of memory in audit_log_move [alloc_skb]
103 3) suppressed due to audit_rate_limit
104 4) suppressed due to audit_backlog_limit
106 static atomic_t audit_lost = ATOMIC_INIT(0);
108 /* The netlink socket. */
109 static struct sock *audit_sock;
111 /* Inotify handle. */
112 struct inotify_handle *audit_ih;
114 /* Hash for inode-based rules */
115 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
117 /* The audit_freelist is a list of pre-allocated audit buffers (if more
118 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
119 * being placed on the freelist). */
120 static DEFINE_SPINLOCK(audit_freelist_lock);
121 static int audit_freelist_count;
122 static LIST_HEAD(audit_freelist);
124 static struct sk_buff_head audit_skb_queue;
125 static struct task_struct *kauditd_task;
126 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
127 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
129 /* Serialize requests from userspace. */
130 static DEFINE_MUTEX(audit_cmd_mutex);
132 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
133 * audit records. Since printk uses a 1024 byte buffer, this buffer
134 * should be at least that large. */
135 #define AUDIT_BUFSIZ 1024
137 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
138 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
139 #define AUDIT_MAXFREE (2*NR_CPUS)
141 /* The audit_buffer is used when formatting an audit record. The caller
142 * locks briefly to get the record off the freelist or to allocate the
143 * buffer, and locks briefly to send the buffer to the netlink layer or
144 * to place it on a transmit queue. Multiple audit_buffers can be in
145 * use simultaneously. */
146 struct audit_buffer {
147 struct list_head list;
148 struct sk_buff *skb; /* formatted skb ready to send */
149 struct audit_context *ctx; /* NULL or associated context */
153 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
155 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
156 nlh->nlmsg_pid = pid;
159 void audit_panic(const char *message)
161 switch (audit_failure)
163 case AUDIT_FAIL_SILENT:
165 case AUDIT_FAIL_PRINTK:
166 printk(KERN_ERR "audit: %s\n", message);
168 case AUDIT_FAIL_PANIC:
169 panic("audit: %s\n", message);
174 static inline int audit_rate_check(void)
176 static unsigned long last_check = 0;
177 static int messages = 0;
178 static DEFINE_SPINLOCK(lock);
181 unsigned long elapsed;
184 if (!audit_rate_limit) return 1;
186 spin_lock_irqsave(&lock, flags);
187 if (++messages < audit_rate_limit) {
191 elapsed = now - last_check;
198 spin_unlock_irqrestore(&lock, flags);
204 * audit_log_lost - conditionally log lost audit message event
205 * @message: the message stating reason for lost audit message
207 * Emit at least 1 message per second, even if audit_rate_check is
209 * Always increment the lost messages counter.
211 void audit_log_lost(const char *message)
213 static unsigned long last_msg = 0;
214 static DEFINE_SPINLOCK(lock);
219 atomic_inc(&audit_lost);
221 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
224 spin_lock_irqsave(&lock, flags);
226 if (now - last_msg > HZ) {
230 spin_unlock_irqrestore(&lock, flags);
235 "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n",
236 atomic_read(&audit_lost),
238 audit_backlog_limit);
239 audit_panic(message);
243 static int audit_log_config_change(char *function_name, int new, int old,
244 uid_t loginuid, u32 sid, int allow_changes)
246 struct audit_buffer *ab;
249 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
250 audit_log_format(ab, "%s=%d old=%d by auid=%u", function_name, new,
256 rc = selinux_sid_to_string(sid, &ctx, &len);
258 audit_log_format(ab, " sid=%u", sid);
259 allow_changes = 0; /* Something weird, deny request */
261 audit_log_format(ab, " subj=%s", ctx);
265 audit_log_format(ab, " res=%d", allow_changes);
270 static int audit_do_config_change(char *function_name, int *to_change,
271 int new, uid_t loginuid, u32 sid)
273 int allow_changes, rc = 0, old = *to_change;
275 /* check if we are locked */
276 if (audit_enabled == AUDIT_LOCKED)
281 if (audit_enabled != AUDIT_OFF) {
282 rc = audit_log_config_change(function_name, new, old,
283 loginuid, sid, allow_changes);
288 /* If we are allowed, make the change */
289 if (allow_changes == 1)
291 /* Not allowed, update reason */
297 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
299 return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
300 limit, loginuid, sid);
303 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
305 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
306 limit, loginuid, sid);
309 static int audit_set_enabled(int state, uid_t loginuid, u32 sid)
311 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
314 return audit_do_config_change("audit_enabled", &audit_enabled, state,
318 static int audit_set_failure(int state, uid_t loginuid, u32 sid)
320 if (state != AUDIT_FAIL_SILENT
321 && state != AUDIT_FAIL_PRINTK
322 && state != AUDIT_FAIL_PANIC)
325 return audit_do_config_change("audit_failure", &audit_failure, state,
329 static int kauditd_thread(void *dummy)
334 while (!kthread_should_stop()) {
335 skb = skb_dequeue(&audit_skb_queue);
336 wake_up(&audit_backlog_wait);
339 int err = netlink_unicast(audit_sock, skb, audit_pid, 0);
341 BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
342 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
346 printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0));
350 DECLARE_WAITQUEUE(wait, current);
351 set_current_state(TASK_INTERRUPTIBLE);
352 add_wait_queue(&kauditd_wait, &wait);
354 if (!skb_queue_len(&audit_skb_queue)) {
359 __set_current_state(TASK_RUNNING);
360 remove_wait_queue(&kauditd_wait, &wait);
366 static int audit_prepare_user_tty(pid_t pid, uid_t loginuid)
368 struct task_struct *tsk;
371 read_lock(&tasklist_lock);
372 tsk = find_task_by_pid(pid);
378 spin_lock_irq(&tsk->sighand->siglock);
379 if (!tsk->signal->audit_tty)
381 spin_unlock_irq(&tsk->sighand->siglock);
385 tty_audit_push_task(tsk, loginuid);
387 read_unlock(&tasklist_lock);
391 int audit_send_list(void *_dest)
393 struct audit_netlink_list *dest = _dest;
397 /* wait for parent to finish and send an ACK */
398 mutex_lock(&audit_cmd_mutex);
399 mutex_unlock(&audit_cmd_mutex);
401 while ((skb = __skb_dequeue(&dest->q)) != NULL)
402 netlink_unicast(audit_sock, skb, pid, 0);
409 #ifdef CONFIG_AUDIT_TREE
410 static int prune_tree_thread(void *unused)
412 mutex_lock(&audit_cmd_mutex);
414 mutex_unlock(&audit_cmd_mutex);
418 void audit_schedule_prune(void)
420 kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
424 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
425 int multi, void *payload, int size)
428 struct nlmsghdr *nlh;
429 int len = NLMSG_SPACE(size);
431 int flags = multi ? NLM_F_MULTI : 0;
432 int t = done ? NLMSG_DONE : type;
434 skb = alloc_skb(len, GFP_KERNEL);
438 nlh = NLMSG_PUT(skb, pid, seq, t, size);
439 nlh->nlmsg_flags = flags;
440 data = NLMSG_DATA(nlh);
441 memcpy(data, payload, size);
444 nlmsg_failure: /* Used by NLMSG_PUT */
451 * audit_send_reply - send an audit reply message via netlink
452 * @pid: process id to send reply to
453 * @seq: sequence number
454 * @type: audit message type
455 * @done: done (last) flag
456 * @multi: multi-part message flag
457 * @payload: payload data
458 * @size: payload size
460 * Allocates an skb, builds the netlink message, and sends it to the pid.
461 * No failure notifications.
463 void audit_send_reply(int pid, int seq, int type, int done, int multi,
464 void *payload, int size)
467 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
470 /* Ignore failure. It'll only happen if the sender goes away,
471 because our timeout is set to infinite. */
472 netlink_unicast(audit_sock, skb, pid, 0);
477 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
480 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
487 case AUDIT_LIST_RULES:
493 case AUDIT_SIGNAL_INFO:
497 case AUDIT_MAKE_EQUIV:
498 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
502 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
503 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
504 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
507 default: /* bad msg */
514 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
516 u32 uid, pid, seq, sid;
518 struct audit_status *status_get, status_set;
520 struct audit_buffer *ab;
521 u16 msg_type = nlh->nlmsg_type;
522 uid_t loginuid; /* loginuid of sender */
523 struct audit_sig_info *sig_data;
527 err = audit_netlink_ok(skb, msg_type);
531 /* As soon as there's any sign of userspace auditd,
532 * start kauditd to talk to it */
534 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
535 if (IS_ERR(kauditd_task)) {
536 err = PTR_ERR(kauditd_task);
541 pid = NETLINK_CREDS(skb)->pid;
542 uid = NETLINK_CREDS(skb)->uid;
543 loginuid = NETLINK_CB(skb).loginuid;
544 sid = NETLINK_CB(skb).sid;
545 seq = nlh->nlmsg_seq;
546 data = NLMSG_DATA(nlh);
550 status_set.enabled = audit_enabled;
551 status_set.failure = audit_failure;
552 status_set.pid = audit_pid;
553 status_set.rate_limit = audit_rate_limit;
554 status_set.backlog_limit = audit_backlog_limit;
555 status_set.lost = atomic_read(&audit_lost);
556 status_set.backlog = skb_queue_len(&audit_skb_queue);
557 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
558 &status_set, sizeof(status_set));
561 if (nlh->nlmsg_len < sizeof(struct audit_status))
563 status_get = (struct audit_status *)data;
564 if (status_get->mask & AUDIT_STATUS_ENABLED) {
565 err = audit_set_enabled(status_get->enabled,
567 if (err < 0) return err;
569 if (status_get->mask & AUDIT_STATUS_FAILURE) {
570 err = audit_set_failure(status_get->failure,
572 if (err < 0) return err;
574 if (status_get->mask & AUDIT_STATUS_PID) {
575 int new_pid = status_get->pid;
577 if (audit_enabled != AUDIT_OFF)
578 audit_log_config_change("audit_pid", new_pid,
584 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
585 err = audit_set_rate_limit(status_get->rate_limit,
587 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
588 err = audit_set_backlog_limit(status_get->backlog_limit,
592 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
593 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
594 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
597 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
600 if (msg_type == AUDIT_USER_TTY) {
601 err = audit_prepare_user_tty(pid, loginuid);
605 ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
608 "user pid=%d uid=%u auid=%u",
611 if (selinux_sid_to_string(
615 /* Maybe call audit_panic? */
621 if (msg_type != AUDIT_USER_TTY)
622 audit_log_format(ab, " msg='%.1024s'",
627 audit_log_format(ab, " msg=");
628 size = nlmsg_len(nlh);
629 audit_log_n_untrustedstring(ab, size,
632 audit_set_pid(ab, pid);
639 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
641 if (audit_enabled == AUDIT_LOCKED) {
642 ab = audit_log_start(NULL, GFP_KERNEL,
643 AUDIT_CONFIG_CHANGE);
646 "pid=%d uid=%u auid=%u",
649 if (selinux_sid_to_string(
653 /* Maybe call audit_panic? */
659 audit_log_format(ab, " audit_enabled=%d res=0",
667 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
668 uid, seq, data, nlmsg_len(nlh),
673 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
675 if (audit_enabled == AUDIT_LOCKED) {
676 ab = audit_log_start(NULL, GFP_KERNEL,
677 AUDIT_CONFIG_CHANGE);
680 "pid=%d uid=%u auid=%u",
683 if (selinux_sid_to_string(
687 /* Maybe call audit_panic? */
693 audit_log_format(ab, " audit_enabled=%d res=0",
700 case AUDIT_LIST_RULES:
701 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
702 uid, seq, data, nlmsg_len(nlh),
707 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
710 audit_log_format(ab, "auid=%u", loginuid);
714 if (selinux_sid_to_string(sid, &ctx, &len))
715 audit_log_format(ab, " ssid=%u", sid);
717 audit_log_format(ab, " subj=%s", ctx);
720 audit_log_format(ab, " op=trim res=1");
723 case AUDIT_MAKE_EQUIV: {
726 size_t len = nlmsg_len(nlh);
730 if (len < 2 * sizeof(u32))
732 memcpy(sizes, bufp, 2 * sizeof(u32));
733 bufp += 2 * sizeof(u32);
734 len -= 2 * sizeof(u32);
735 old = audit_unpack_string(&bufp, &len, sizes[0]);
740 new = audit_unpack_string(&bufp, &len, sizes[1]);
746 /* OK, here comes... */
747 err = audit_tag_tree(old, new);
749 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
755 audit_log_format(ab, "auid=%u", loginuid);
759 if (selinux_sid_to_string(sid, &ctx, &len))
760 audit_log_format(ab, " ssid=%u", sid);
762 audit_log_format(ab, " subj=%s", ctx);
765 audit_log_format(ab, " op=make_equiv old=");
766 audit_log_untrustedstring(ab, old);
767 audit_log_format(ab, " new=");
768 audit_log_untrustedstring(ab, new);
769 audit_log_format(ab, " res=%d", !err);
775 case AUDIT_SIGNAL_INFO:
776 err = selinux_sid_to_string(audit_sig_sid, &ctx, &len);
779 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
784 sig_data->uid = audit_sig_uid;
785 sig_data->pid = audit_sig_pid;
786 memcpy(sig_data->ctx, ctx, len);
788 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
789 0, 0, sig_data, sizeof(*sig_data) + len);
792 case AUDIT_TTY_GET: {
793 struct audit_tty_status s;
794 struct task_struct *tsk;
796 read_lock(&tasklist_lock);
797 tsk = find_task_by_pid(pid);
801 spin_lock_irq(&tsk->sighand->siglock);
802 s.enabled = tsk->signal->audit_tty != 0;
803 spin_unlock_irq(&tsk->sighand->siglock);
805 read_unlock(&tasklist_lock);
806 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0,
810 case AUDIT_TTY_SET: {
811 struct audit_tty_status *s;
812 struct task_struct *tsk;
814 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
817 if (s->enabled != 0 && s->enabled != 1)
819 read_lock(&tasklist_lock);
820 tsk = find_task_by_pid(pid);
824 spin_lock_irq(&tsk->sighand->siglock);
825 tsk->signal->audit_tty = s->enabled != 0;
826 spin_unlock_irq(&tsk->sighand->siglock);
828 read_unlock(&tasklist_lock);
836 return err < 0 ? err : 0;
840 * Get message from skb (based on rtnetlink_rcv_skb). Each message is
841 * processed by audit_receive_msg. Malformed skbs with wrong length are
842 * discarded silently.
844 static void audit_receive_skb(struct sk_buff *skb)
847 struct nlmsghdr *nlh;
850 while (skb->len >= NLMSG_SPACE(0)) {
851 nlh = nlmsg_hdr(skb);
852 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
854 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
857 if ((err = audit_receive_msg(skb, nlh))) {
858 netlink_ack(skb, nlh, err);
859 } else if (nlh->nlmsg_flags & NLM_F_ACK)
860 netlink_ack(skb, nlh, 0);
865 /* Receive messages from netlink socket. */
866 static void audit_receive(struct sk_buff *skb)
868 mutex_lock(&audit_cmd_mutex);
869 audit_receive_skb(skb);
870 mutex_unlock(&audit_cmd_mutex);
873 #ifdef CONFIG_AUDITSYSCALL
874 static const struct inotify_operations audit_inotify_ops = {
875 .handle_event = audit_handle_ievent,
876 .destroy_watch = audit_free_parent,
880 /* Initialize audit support at boot time. */
881 static int __init audit_init(void)
885 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
886 audit_default ? "enabled" : "disabled");
887 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
888 audit_receive, NULL, THIS_MODULE);
890 audit_panic("cannot initialize netlink socket");
892 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
894 skb_queue_head_init(&audit_skb_queue);
895 audit_initialized = 1;
896 audit_enabled = audit_default;
898 /* Register the callback with selinux. This callback will be invoked
899 * when a new policy is loaded. */
900 selinux_audit_set_callback(&selinux_audit_rule_update);
902 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
904 #ifdef CONFIG_AUDITSYSCALL
905 audit_ih = inotify_init(&audit_inotify_ops);
906 if (IS_ERR(audit_ih))
907 audit_panic("cannot initialize inotify handle");
910 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
911 INIT_LIST_HEAD(&audit_inode_hash[i]);
915 __initcall(audit_init);
917 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
918 static int __init audit_enable(char *str)
920 audit_default = !!simple_strtol(str, NULL, 0);
921 printk(KERN_INFO "audit: %s%s\n",
922 audit_default ? "enabled" : "disabled",
923 audit_initialized ? "" : " (after initialization)");
924 if (audit_initialized)
925 audit_enabled = audit_default;
929 __setup("audit=", audit_enable);
931 static void audit_buffer_free(struct audit_buffer *ab)
941 spin_lock_irqsave(&audit_freelist_lock, flags);
942 if (audit_freelist_count > AUDIT_MAXFREE)
945 audit_freelist_count++;
946 list_add(&ab->list, &audit_freelist);
948 spin_unlock_irqrestore(&audit_freelist_lock, flags);
951 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
952 gfp_t gfp_mask, int type)
955 struct audit_buffer *ab = NULL;
956 struct nlmsghdr *nlh;
958 spin_lock_irqsave(&audit_freelist_lock, flags);
959 if (!list_empty(&audit_freelist)) {
960 ab = list_entry(audit_freelist.next,
961 struct audit_buffer, list);
963 --audit_freelist_count;
965 spin_unlock_irqrestore(&audit_freelist_lock, flags);
968 ab = kmalloc(sizeof(*ab), gfp_mask);
973 ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
978 ab->gfp_mask = gfp_mask;
979 nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
980 nlh->nlmsg_type = type;
981 nlh->nlmsg_flags = 0;
986 audit_buffer_free(ab);
991 * audit_serial - compute a serial number for the audit record
993 * Compute a serial number for the audit record. Audit records are
994 * written to user-space as soon as they are generated, so a complete
995 * audit record may be written in several pieces. The timestamp of the
996 * record and this serial number are used by the user-space tools to
997 * determine which pieces belong to the same audit record. The
998 * (timestamp,serial) tuple is unique for each syscall and is live from
999 * syscall entry to syscall exit.
1001 * NOTE: Another possibility is to store the formatted records off the
1002 * audit context (for those records that have a context), and emit them
1003 * all at syscall exit. However, this could delay the reporting of
1004 * significant errors until syscall exit (or never, if the system
1007 unsigned int audit_serial(void)
1009 static DEFINE_SPINLOCK(serial_lock);
1010 static unsigned int serial = 0;
1012 unsigned long flags;
1015 spin_lock_irqsave(&serial_lock, flags);
1018 } while (unlikely(!ret));
1019 spin_unlock_irqrestore(&serial_lock, flags);
1024 static inline void audit_get_stamp(struct audit_context *ctx,
1025 struct timespec *t, unsigned int *serial)
1028 auditsc_get_stamp(ctx, t, serial);
1031 *serial = audit_serial();
1035 /* Obtain an audit buffer. This routine does locking to obtain the
1036 * audit buffer, but then no locking is required for calls to
1037 * audit_log_*format. If the tsk is a task that is currently in a
1038 * syscall, then the syscall is marked as auditable and an audit record
1039 * will be written at syscall exit. If there is no associated task, tsk
1040 * should be NULL. */
1043 * audit_log_start - obtain an audit buffer
1044 * @ctx: audit_context (may be NULL)
1045 * @gfp_mask: type of allocation
1046 * @type: audit message type
1048 * Returns audit_buffer pointer on success or NULL on error.
1050 * Obtain an audit buffer. This routine does locking to obtain the
1051 * audit buffer, but then no locking is required for calls to
1052 * audit_log_*format. If the task (ctx) is a task that is currently in a
1053 * syscall, then the syscall is marked as auditable and an audit record
1054 * will be written at syscall exit. If there is no associated task, then
1055 * task context (ctx) should be NULL.
1057 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1060 struct audit_buffer *ab = NULL;
1062 unsigned int serial;
1064 unsigned long timeout_start = jiffies;
1066 if (!audit_initialized)
1069 if (unlikely(audit_filter_type(type)))
1072 if (gfp_mask & __GFP_WAIT)
1075 reserve = 5; /* Allow atomic callers to go up to five
1076 entries over the normal backlog limit */
1078 while (audit_backlog_limit
1079 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1080 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1081 && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1083 /* Wait for auditd to drain the queue a little */
1084 DECLARE_WAITQUEUE(wait, current);
1085 set_current_state(TASK_INTERRUPTIBLE);
1086 add_wait_queue(&audit_backlog_wait, &wait);
1088 if (audit_backlog_limit &&
1089 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1090 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1092 __set_current_state(TASK_RUNNING);
1093 remove_wait_queue(&audit_backlog_wait, &wait);
1096 if (audit_rate_check())
1098 "audit: audit_backlog=%d > "
1099 "audit_backlog_limit=%d\n",
1100 skb_queue_len(&audit_skb_queue),
1101 audit_backlog_limit);
1102 audit_log_lost("backlog limit exceeded");
1103 audit_backlog_wait_time = audit_backlog_wait_overflow;
1104 wake_up(&audit_backlog_wait);
1108 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1110 audit_log_lost("out of memory in audit_log_start");
1114 audit_get_stamp(ab->ctx, &t, &serial);
1116 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1117 t.tv_sec, t.tv_nsec/1000000, serial);
1122 * audit_expand - expand skb in the audit buffer
1124 * @extra: space to add at tail of the skb
1126 * Returns 0 (no space) on failed expansion, or available space if
1129 static inline int audit_expand(struct audit_buffer *ab, int extra)
1131 struct sk_buff *skb = ab->skb;
1132 int oldtail = skb_tailroom(skb);
1133 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1134 int newtail = skb_tailroom(skb);
1137 audit_log_lost("out of memory in audit_expand");
1141 skb->truesize += newtail - oldtail;
1146 * Format an audit message into the audit buffer. If there isn't enough
1147 * room in the audit buffer, more room will be allocated and vsnprint
1148 * will be called a second time. Currently, we assume that a printk
1149 * can't format message larger than 1024 bytes, so we don't either.
1151 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1155 struct sk_buff *skb;
1163 avail = skb_tailroom(skb);
1165 avail = audit_expand(ab, AUDIT_BUFSIZ);
1169 va_copy(args2, args);
1170 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1172 /* The printk buffer is 1024 bytes long, so if we get
1173 * here and AUDIT_BUFSIZ is at least 1024, then we can
1174 * log everything that printk could have logged. */
1175 avail = audit_expand(ab,
1176 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1179 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1188 * audit_log_format - format a message into the audit buffer.
1190 * @fmt: format string
1191 * @...: optional parameters matching @fmt string
1193 * All the work is done in audit_log_vformat.
1195 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1201 va_start(args, fmt);
1202 audit_log_vformat(ab, fmt, args);
1207 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1208 * @ab: the audit_buffer
1209 * @buf: buffer to convert to hex
1210 * @len: length of @buf to be converted
1212 * No return value; failure to expand is silently ignored.
1214 * This function will take the passed buf and convert it into a string of
1215 * ascii hex digits. The new string is placed onto the skb.
1217 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1220 int i, avail, new_len;
1222 struct sk_buff *skb;
1223 static const unsigned char *hex = "0123456789ABCDEF";
1230 avail = skb_tailroom(skb);
1232 if (new_len >= avail) {
1233 /* Round the buffer request up to the next multiple */
1234 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1235 avail = audit_expand(ab, new_len);
1240 ptr = skb_tail_pointer(skb);
1241 for (i=0; i<len; i++) {
1242 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1243 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1246 skb_put(skb, len << 1); /* new string is twice the old string */
1250 * Format a string of no more than slen characters into the audit buffer,
1251 * enclosed in quote marks.
1253 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1258 struct sk_buff *skb;
1265 avail = skb_tailroom(skb);
1266 new_len = slen + 3; /* enclosing quotes + null terminator */
1267 if (new_len > avail) {
1268 avail = audit_expand(ab, new_len);
1272 ptr = skb_tail_pointer(skb);
1274 memcpy(ptr, string, slen);
1278 skb_put(skb, slen + 2); /* don't include null terminator */
1282 * audit_string_contains_control - does a string need to be logged in hex
1283 * @string - string to be checked
1284 * @len - max length of the string to check
1286 int audit_string_contains_control(const char *string, size_t len)
1288 const unsigned char *p;
1289 for (p = string; p < (const unsigned char *)string + len && *p; p++) {
1290 if (*p == '"' || *p < 0x21 || *p > 0x7f)
1297 * audit_log_n_untrustedstring - log a string that may contain random characters
1299 * @len: lenth of string (not including trailing null)
1300 * @string: string to be logged
1302 * This code will escape a string that is passed to it if the string
1303 * contains a control character, unprintable character, double quote mark,
1304 * or a space. Unescaped strings will start and end with a double quote mark.
1305 * Strings that are escaped are printed in hex (2 digits per char).
1307 * The caller specifies the number of characters in the string to log, which may
1308 * or may not be the entire string.
1310 void audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1313 if (audit_string_contains_control(string, len))
1314 audit_log_hex(ab, string, len);
1316 audit_log_n_string(ab, len, string);
1320 * audit_log_untrustedstring - log a string that may contain random characters
1322 * @string: string to be logged
1324 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1325 * determine string length.
1327 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1329 audit_log_n_untrustedstring(ab, strlen(string), string);
1332 /* This is a helper-function to print the escaped d_path */
1333 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1334 struct dentry *dentry, struct vfsmount *vfsmnt)
1339 audit_log_format(ab, " %s", prefix);
1341 /* We will allow 11 spaces for ' (deleted)' to be appended */
1342 path = kmalloc(PATH_MAX+11, ab->gfp_mask);
1344 audit_log_format(ab, "<no memory>");
1347 p = d_path(dentry, vfsmnt, path, PATH_MAX+11);
1348 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1349 /* FIXME: can we save some information here? */
1350 audit_log_format(ab, "<too long>");
1352 audit_log_untrustedstring(ab, p);
1357 * audit_log_end - end one audit record
1358 * @ab: the audit_buffer
1360 * The netlink_* functions cannot be called inside an irq context, so
1361 * the audit buffer is placed on a queue and a tasklet is scheduled to
1362 * remove them from the queue outside the irq context. May be called in
1365 void audit_log_end(struct audit_buffer *ab)
1369 if (!audit_rate_check()) {
1370 audit_log_lost("rate limit exceeded");
1373 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1374 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1375 skb_queue_tail(&audit_skb_queue, ab->skb);
1377 wake_up_interruptible(&kauditd_wait);
1379 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1380 printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, ab->skb->data + NLMSG_SPACE(0));
1383 audit_buffer_free(ab);
1387 * audit_log - Log an audit record
1388 * @ctx: audit context
1389 * @gfp_mask: type of allocation
1390 * @type: audit message type
1391 * @fmt: format string to use
1392 * @...: variable parameters matching the format string
1394 * This is a convenience function that calls audit_log_start,
1395 * audit_log_vformat, and audit_log_end. It may be called
1398 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1399 const char *fmt, ...)
1401 struct audit_buffer *ab;
1404 ab = audit_log_start(ctx, gfp_mask, type);
1406 va_start(args, fmt);
1407 audit_log_vformat(ab, fmt, args);
1413 EXPORT_SYMBOL(audit_log_start);
1414 EXPORT_SYMBOL(audit_log_end);
1415 EXPORT_SYMBOL(audit_log_format);
1416 EXPORT_SYMBOL(audit_log);