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 <linux/atomic.h>
48 #include <linux/export.h>
49 #include <linux/slab.h>
50 #include <linux/err.h>
51 #include <linux/kthread.h>
53 #include <linux/audit.h>
56 #include <net/netlink.h>
57 #include <linux/skbuff.h>
58 #ifdef CONFIG_SECURITY
59 #include <linux/security.h>
61 #include <linux/netlink.h>
62 #include <linux/freezer.h>
63 #include <linux/tty.h>
64 #include <linux/pid_namespace.h>
68 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
69 * (Initialization happens after skb_init is called.) */
70 #define AUDIT_DISABLED -1
71 #define AUDIT_UNINITIALIZED 0
72 #define AUDIT_INITIALIZED 1
73 static int audit_initialized;
77 #define AUDIT_LOCKED 2
79 int audit_ever_enabled;
81 EXPORT_SYMBOL_GPL(audit_enabled);
83 /* Default state when kernel boots without any parameters. */
84 static int audit_default;
86 /* If auditing cannot proceed, audit_failure selects what happens. */
87 static int audit_failure = AUDIT_FAIL_PRINTK;
90 * If audit records are to be written to the netlink socket, audit_pid
91 * contains the pid of the auditd process and audit_nlk_pid contains
92 * the pid to use to send netlink messages to that process.
95 static int audit_nlk_pid;
97 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
98 * to that number per second. This prevents DoS attacks, but results in
99 * audit records being dropped. */
100 static int audit_rate_limit;
102 /* Number of outstanding audit_buffers allowed. */
103 static int audit_backlog_limit = 64;
104 static int audit_backlog_wait_time = 60 * HZ;
105 static int audit_backlog_wait_overflow = 0;
107 /* The identity of the user shutting down the audit system. */
108 uid_t audit_sig_uid = -1;
109 pid_t audit_sig_pid = -1;
110 u32 audit_sig_sid = 0;
112 /* Records can be lost in several ways:
113 0) [suppressed in audit_alloc]
114 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
115 2) out of memory in audit_log_move [alloc_skb]
116 3) suppressed due to audit_rate_limit
117 4) suppressed due to audit_backlog_limit
119 static atomic_t audit_lost = ATOMIC_INIT(0);
121 /* The netlink socket. */
122 static struct sock *audit_sock;
124 /* Hash for inode-based rules */
125 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
127 /* The audit_freelist is a list of pre-allocated audit buffers (if more
128 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
129 * being placed on the freelist). */
130 static DEFINE_SPINLOCK(audit_freelist_lock);
131 static int audit_freelist_count;
132 static LIST_HEAD(audit_freelist);
134 static struct sk_buff_head audit_skb_queue;
135 /* queue of skbs to send to auditd when/if it comes back */
136 static struct sk_buff_head audit_skb_hold_queue;
137 static struct task_struct *kauditd_task;
138 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
139 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
141 /* Serialize requests from userspace. */
142 DEFINE_MUTEX(audit_cmd_mutex);
144 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
145 * audit records. Since printk uses a 1024 byte buffer, this buffer
146 * should be at least that large. */
147 #define AUDIT_BUFSIZ 1024
149 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
150 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
151 #define AUDIT_MAXFREE (2*NR_CPUS)
153 /* The audit_buffer is used when formatting an audit record. The caller
154 * locks briefly to get the record off the freelist or to allocate the
155 * buffer, and locks briefly to send the buffer to the netlink layer or
156 * to place it on a transmit queue. Multiple audit_buffers can be in
157 * use simultaneously. */
158 struct audit_buffer {
159 struct list_head list;
160 struct sk_buff *skb; /* formatted skb ready to send */
161 struct audit_context *ctx; /* NULL or associated context */
170 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
173 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
174 nlh->nlmsg_pid = pid;
178 void audit_panic(const char *message)
180 switch (audit_failure)
182 case AUDIT_FAIL_SILENT:
184 case AUDIT_FAIL_PRINTK:
185 if (printk_ratelimit())
186 printk(KERN_ERR "audit: %s\n", message);
188 case AUDIT_FAIL_PANIC:
189 /* test audit_pid since printk is always losey, why bother? */
191 panic("audit: %s\n", message);
196 static inline int audit_rate_check(void)
198 static unsigned long last_check = 0;
199 static int messages = 0;
200 static DEFINE_SPINLOCK(lock);
203 unsigned long elapsed;
206 if (!audit_rate_limit) return 1;
208 spin_lock_irqsave(&lock, flags);
209 if (++messages < audit_rate_limit) {
213 elapsed = now - last_check;
220 spin_unlock_irqrestore(&lock, flags);
226 * audit_log_lost - conditionally log lost audit message event
227 * @message: the message stating reason for lost audit message
229 * Emit at least 1 message per second, even if audit_rate_check is
231 * Always increment the lost messages counter.
233 void audit_log_lost(const char *message)
235 static unsigned long last_msg = 0;
236 static DEFINE_SPINLOCK(lock);
241 atomic_inc(&audit_lost);
243 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
246 spin_lock_irqsave(&lock, flags);
248 if (now - last_msg > HZ) {
252 spin_unlock_irqrestore(&lock, flags);
256 if (printk_ratelimit())
258 "audit: audit_lost=%d audit_rate_limit=%d "
259 "audit_backlog_limit=%d\n",
260 atomic_read(&audit_lost),
262 audit_backlog_limit);
263 audit_panic(message);
267 static int audit_log_config_change(char *function_name, int new, int old,
268 uid_t loginuid, u32 sessionid, u32 sid,
271 struct audit_buffer *ab;
274 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
275 audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
276 old, loginuid, sessionid);
281 rc = security_secid_to_secctx(sid, &ctx, &len);
283 audit_log_format(ab, " sid=%u", sid);
284 allow_changes = 0; /* Something weird, deny request */
286 audit_log_format(ab, " subj=%s", ctx);
287 security_release_secctx(ctx, len);
290 audit_log_format(ab, " res=%d", allow_changes);
295 static int audit_do_config_change(char *function_name, int *to_change,
296 int new, uid_t loginuid, u32 sessionid,
299 int allow_changes, rc = 0, old = *to_change;
301 /* check if we are locked */
302 if (audit_enabled == AUDIT_LOCKED)
307 if (audit_enabled != AUDIT_OFF) {
308 rc = audit_log_config_change(function_name, new, old, loginuid,
309 sessionid, sid, allow_changes);
314 /* If we are allowed, make the change */
315 if (allow_changes == 1)
317 /* Not allowed, update reason */
323 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
326 return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
327 limit, loginuid, sessionid, sid);
330 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
333 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
334 limit, loginuid, sessionid, sid);
337 static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
340 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
343 rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
344 loginuid, sessionid, sid);
347 audit_ever_enabled |= !!state;
352 static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
354 if (state != AUDIT_FAIL_SILENT
355 && state != AUDIT_FAIL_PRINTK
356 && state != AUDIT_FAIL_PANIC)
359 return audit_do_config_change("audit_failure", &audit_failure, state,
360 loginuid, sessionid, sid);
364 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
365 * already have been sent via prink/syslog and so if these messages are dropped
366 * it is not a huge concern since we already passed the audit_log_lost()
367 * notification and stuff. This is just nice to get audit messages during
368 * boot before auditd is running or messages generated while auditd is stopped.
369 * This only holds messages is audit_default is set, aka booting with audit=1
370 * or building your kernel that way.
372 static void audit_hold_skb(struct sk_buff *skb)
375 skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
376 skb_queue_tail(&audit_skb_hold_queue, skb);
382 * For one reason or another this nlh isn't getting delivered to the userspace
383 * audit daemon, just send it to printk.
385 static void audit_printk_skb(struct sk_buff *skb)
387 struct nlmsghdr *nlh = nlmsg_hdr(skb);
388 char *data = nlmsg_data(nlh);
390 if (nlh->nlmsg_type != AUDIT_EOE) {
391 if (printk_ratelimit())
392 printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
394 audit_log_lost("printk limit exceeded\n");
400 static void kauditd_send_skb(struct sk_buff *skb)
403 /* take a reference in case we can't send it and we want to hold it */
405 err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
407 BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
408 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
409 audit_log_lost("auditd disappeared\n");
411 /* we might get lucky and get this in the next auditd */
414 /* drop the extra reference if sent ok */
418 static int kauditd_thread(void *dummy)
423 while (!kthread_should_stop()) {
425 * if auditd just started drain the queue of messages already
426 * sent to syslog/printk. remember loss here is ok. we already
427 * called audit_log_lost() if it didn't go out normally. so the
428 * race between the skb_dequeue and the next check for audit_pid
431 * if you ever find kauditd to be too slow we can get a perf win
432 * by doing our own locking and keeping better track if there
433 * are messages in this queue. I don't see the need now, but
434 * in 5 years when I want to play with this again I'll see this
435 * note and still have no friggin idea what i'm thinking today.
437 if (audit_default && audit_pid) {
438 skb = skb_dequeue(&audit_skb_hold_queue);
440 while (skb && audit_pid) {
441 kauditd_send_skb(skb);
442 skb = skb_dequeue(&audit_skb_hold_queue);
447 skb = skb_dequeue(&audit_skb_queue);
448 wake_up(&audit_backlog_wait);
451 kauditd_send_skb(skb);
453 audit_printk_skb(skb);
455 DECLARE_WAITQUEUE(wait, current);
456 set_current_state(TASK_INTERRUPTIBLE);
457 add_wait_queue(&kauditd_wait, &wait);
459 if (!skb_queue_len(&audit_skb_queue)) {
464 __set_current_state(TASK_RUNNING);
465 remove_wait_queue(&kauditd_wait, &wait);
471 int audit_send_list(void *_dest)
473 struct audit_netlink_list *dest = _dest;
477 /* wait for parent to finish and send an ACK */
478 mutex_lock(&audit_cmd_mutex);
479 mutex_unlock(&audit_cmd_mutex);
481 while ((skb = __skb_dequeue(&dest->q)) != NULL)
482 netlink_unicast(audit_sock, skb, pid, 0);
489 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
490 int multi, const void *payload, int size)
493 struct nlmsghdr *nlh;
495 int flags = multi ? NLM_F_MULTI : 0;
496 int t = done ? NLMSG_DONE : type;
498 skb = nlmsg_new(size, GFP_KERNEL);
502 nlh = nlmsg_put(skb, pid, seq, t, size, flags);
505 data = nlmsg_data(nlh);
506 memcpy(data, payload, size);
514 static int audit_send_reply_thread(void *arg)
516 struct audit_reply *reply = (struct audit_reply *)arg;
518 mutex_lock(&audit_cmd_mutex);
519 mutex_unlock(&audit_cmd_mutex);
521 /* Ignore failure. It'll only happen if the sender goes away,
522 because our timeout is set to infinite. */
523 netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
528 * audit_send_reply - send an audit reply message via netlink
529 * @pid: process id to send reply to
530 * @seq: sequence number
531 * @type: audit message type
532 * @done: done (last) flag
533 * @multi: multi-part message flag
534 * @payload: payload data
535 * @size: payload size
537 * Allocates an skb, builds the netlink message, and sends it to the pid.
538 * No failure notifications.
540 static void audit_send_reply(int pid, int seq, int type, int done, int multi,
541 const void *payload, int size)
544 struct task_struct *tsk;
545 struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
551 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
558 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
567 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
570 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
574 /* Only support the initial namespaces for now. */
575 if ((current_user_ns() != &init_user_ns) ||
576 (task_active_pid_ns(current) != &init_pid_ns))
582 case AUDIT_LIST_RULES:
588 case AUDIT_SIGNAL_INFO:
592 case AUDIT_MAKE_EQUIV:
593 if (!capable(CAP_AUDIT_CONTROL))
597 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
598 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
599 if (!capable(CAP_AUDIT_WRITE))
602 default: /* bad msg */
609 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
610 u32 pid, u32 uid, uid_t auid, u32 ses,
617 if (!audit_enabled) {
622 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
623 audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
624 pid, uid, auid, ses);
626 rc = security_secid_to_secctx(sid, &ctx, &len);
628 audit_log_format(*ab, " ssid=%u", sid);
630 audit_log_format(*ab, " subj=%s", ctx);
631 security_release_secctx(ctx, len);
638 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
640 u32 uid, pid, seq, sid;
642 struct audit_status *status_get, status_set;
644 struct audit_buffer *ab;
645 u16 msg_type = nlh->nlmsg_type;
646 uid_t loginuid; /* loginuid of sender */
648 struct audit_sig_info *sig_data;
652 err = audit_netlink_ok(skb, msg_type);
656 /* As soon as there's any sign of userspace auditd,
657 * start kauditd to talk to it */
659 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
660 if (IS_ERR(kauditd_task)) {
661 err = PTR_ERR(kauditd_task);
666 pid = NETLINK_CREDS(skb)->pid;
667 uid = NETLINK_CREDS(skb)->uid;
668 loginuid = audit_get_loginuid(current);
669 sessionid = audit_get_sessionid(current);
670 security_task_getsecid(current, &sid);
671 seq = nlh->nlmsg_seq;
672 data = nlmsg_data(nlh);
676 status_set.enabled = audit_enabled;
677 status_set.failure = audit_failure;
678 status_set.pid = audit_pid;
679 status_set.rate_limit = audit_rate_limit;
680 status_set.backlog_limit = audit_backlog_limit;
681 status_set.lost = atomic_read(&audit_lost);
682 status_set.backlog = skb_queue_len(&audit_skb_queue);
683 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
684 &status_set, sizeof(status_set));
687 if (nlh->nlmsg_len < sizeof(struct audit_status))
689 status_get = (struct audit_status *)data;
690 if (status_get->mask & AUDIT_STATUS_ENABLED) {
691 err = audit_set_enabled(status_get->enabled,
692 loginuid, sessionid, sid);
696 if (status_get->mask & AUDIT_STATUS_FAILURE) {
697 err = audit_set_failure(status_get->failure,
698 loginuid, sessionid, sid);
702 if (status_get->mask & AUDIT_STATUS_PID) {
703 int new_pid = status_get->pid;
705 if (audit_enabled != AUDIT_OFF)
706 audit_log_config_change("audit_pid", new_pid,
711 audit_nlk_pid = NETLINK_CB(skb).pid;
713 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
714 err = audit_set_rate_limit(status_get->rate_limit,
715 loginuid, sessionid, sid);
719 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
720 err = audit_set_backlog_limit(status_get->backlog_limit,
721 loginuid, sessionid, sid);
724 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
725 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
726 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
729 err = audit_filter_user();
732 if (msg_type == AUDIT_USER_TTY) {
733 err = tty_audit_push_task(current, loginuid,
738 audit_log_common_recv_msg(&ab, msg_type, pid, uid,
739 loginuid, sessionid, sid);
741 if (msg_type != AUDIT_USER_TTY)
742 audit_log_format(ab, " msg='%.1024s'",
747 audit_log_format(ab, " msg=");
748 size = nlmsg_len(nlh);
750 ((unsigned char *)data)[size - 1] == '\0')
752 audit_log_n_untrustedstring(ab, data, size);
754 audit_set_pid(ab, pid);
760 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
762 if (audit_enabled == AUDIT_LOCKED) {
763 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
764 uid, loginuid, sessionid, sid);
766 audit_log_format(ab, " audit_enabled=%d res=0",
773 err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
774 uid, seq, data, nlmsg_len(nlh),
775 loginuid, sessionid, sid);
779 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
781 if (audit_enabled == AUDIT_LOCKED) {
782 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
783 uid, loginuid, sessionid, sid);
785 audit_log_format(ab, " audit_enabled=%d res=0",
791 case AUDIT_LIST_RULES:
792 err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
793 uid, seq, data, nlmsg_len(nlh),
794 loginuid, sessionid, sid);
799 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
800 uid, loginuid, sessionid, sid);
802 audit_log_format(ab, " op=trim res=1");
805 case AUDIT_MAKE_EQUIV: {
808 size_t msglen = nlmsg_len(nlh);
812 if (msglen < 2 * sizeof(u32))
814 memcpy(sizes, bufp, 2 * sizeof(u32));
815 bufp += 2 * sizeof(u32);
816 msglen -= 2 * sizeof(u32);
817 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
822 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
828 /* OK, here comes... */
829 err = audit_tag_tree(old, new);
831 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
832 uid, loginuid, sessionid, sid);
834 audit_log_format(ab, " op=make_equiv old=");
835 audit_log_untrustedstring(ab, old);
836 audit_log_format(ab, " new=");
837 audit_log_untrustedstring(ab, new);
838 audit_log_format(ab, " res=%d", !err);
844 case AUDIT_SIGNAL_INFO:
847 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
851 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
854 security_release_secctx(ctx, len);
857 sig_data->uid = audit_sig_uid;
858 sig_data->pid = audit_sig_pid;
860 memcpy(sig_data->ctx, ctx, len);
861 security_release_secctx(ctx, len);
863 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
864 0, 0, sig_data, sizeof(*sig_data) + len);
867 case AUDIT_TTY_GET: {
868 struct audit_tty_status s;
869 struct task_struct *tsk;
873 tsk = find_task_by_vpid(pid);
874 if (tsk && lock_task_sighand(tsk, &flags)) {
875 s.enabled = tsk->signal->audit_tty != 0;
876 unlock_task_sighand(tsk, &flags);
882 audit_send_reply(NETLINK_CB(skb).pid, seq,
883 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
886 case AUDIT_TTY_SET: {
887 struct audit_tty_status *s;
888 struct task_struct *tsk;
891 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
894 if (s->enabled != 0 && s->enabled != 1)
897 tsk = find_task_by_vpid(pid);
898 if (tsk && lock_task_sighand(tsk, &flags)) {
899 tsk->signal->audit_tty = s->enabled != 0;
900 unlock_task_sighand(tsk, &flags);
911 return err < 0 ? err : 0;
915 * Get message from skb. Each message is processed by audit_receive_msg.
916 * Malformed skbs with wrong length are discarded silently.
918 static void audit_receive_skb(struct sk_buff *skb)
920 struct nlmsghdr *nlh;
922 * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
923 * if the nlmsg_len was not aligned
928 nlh = nlmsg_hdr(skb);
931 while (NLMSG_OK(nlh, len)) {
932 err = audit_receive_msg(skb, nlh);
933 /* if err or if this message says it wants a response */
934 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
935 netlink_ack(skb, nlh, err);
937 nlh = NLMSG_NEXT(nlh, len);
941 /* Receive messages from netlink socket. */
942 static void audit_receive(struct sk_buff *skb)
944 mutex_lock(&audit_cmd_mutex);
945 audit_receive_skb(skb);
946 mutex_unlock(&audit_cmd_mutex);
949 /* Initialize audit support at boot time. */
950 static int __init audit_init(void)
953 struct netlink_kernel_cfg cfg = {
954 .input = audit_receive,
957 if (audit_initialized == AUDIT_DISABLED)
960 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
961 audit_default ? "enabled" : "disabled");
962 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT,
965 audit_panic("cannot initialize netlink socket");
967 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
969 skb_queue_head_init(&audit_skb_queue);
970 skb_queue_head_init(&audit_skb_hold_queue);
971 audit_initialized = AUDIT_INITIALIZED;
972 audit_enabled = audit_default;
973 audit_ever_enabled |= !!audit_default;
975 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
977 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
978 INIT_LIST_HEAD(&audit_inode_hash[i]);
982 __initcall(audit_init);
984 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
985 static int __init audit_enable(char *str)
987 audit_default = !!simple_strtol(str, NULL, 0);
989 audit_initialized = AUDIT_DISABLED;
991 printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
993 if (audit_initialized == AUDIT_INITIALIZED) {
994 audit_enabled = audit_default;
995 audit_ever_enabled |= !!audit_default;
996 } else if (audit_initialized == AUDIT_UNINITIALIZED) {
997 printk(" (after initialization)");
999 printk(" (until reboot)");
1006 __setup("audit=", audit_enable);
1008 static void audit_buffer_free(struct audit_buffer *ab)
1010 unsigned long flags;
1018 spin_lock_irqsave(&audit_freelist_lock, flags);
1019 if (audit_freelist_count > AUDIT_MAXFREE)
1022 audit_freelist_count++;
1023 list_add(&ab->list, &audit_freelist);
1025 spin_unlock_irqrestore(&audit_freelist_lock, flags);
1028 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1029 gfp_t gfp_mask, int type)
1031 unsigned long flags;
1032 struct audit_buffer *ab = NULL;
1033 struct nlmsghdr *nlh;
1035 spin_lock_irqsave(&audit_freelist_lock, flags);
1036 if (!list_empty(&audit_freelist)) {
1037 ab = list_entry(audit_freelist.next,
1038 struct audit_buffer, list);
1039 list_del(&ab->list);
1040 --audit_freelist_count;
1042 spin_unlock_irqrestore(&audit_freelist_lock, flags);
1045 ab = kmalloc(sizeof(*ab), gfp_mask);
1051 ab->gfp_mask = gfp_mask;
1053 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1057 nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1067 audit_buffer_free(ab);
1072 * audit_serial - compute a serial number for the audit record
1074 * Compute a serial number for the audit record. Audit records are
1075 * written to user-space as soon as they are generated, so a complete
1076 * audit record may be written in several pieces. The timestamp of the
1077 * record and this serial number are used by the user-space tools to
1078 * determine which pieces belong to the same audit record. The
1079 * (timestamp,serial) tuple is unique for each syscall and is live from
1080 * syscall entry to syscall exit.
1082 * NOTE: Another possibility is to store the formatted records off the
1083 * audit context (for those records that have a context), and emit them
1084 * all at syscall exit. However, this could delay the reporting of
1085 * significant errors until syscall exit (or never, if the system
1088 unsigned int audit_serial(void)
1090 static DEFINE_SPINLOCK(serial_lock);
1091 static unsigned int serial = 0;
1093 unsigned long flags;
1096 spin_lock_irqsave(&serial_lock, flags);
1099 } while (unlikely(!ret));
1100 spin_unlock_irqrestore(&serial_lock, flags);
1105 static inline void audit_get_stamp(struct audit_context *ctx,
1106 struct timespec *t, unsigned int *serial)
1108 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1110 *serial = audit_serial();
1114 /* Obtain an audit buffer. This routine does locking to obtain the
1115 * audit buffer, but then no locking is required for calls to
1116 * audit_log_*format. If the tsk is a task that is currently in a
1117 * syscall, then the syscall is marked as auditable and an audit record
1118 * will be written at syscall exit. If there is no associated task, tsk
1119 * should be NULL. */
1122 * audit_log_start - obtain an audit buffer
1123 * @ctx: audit_context (may be NULL)
1124 * @gfp_mask: type of allocation
1125 * @type: audit message type
1127 * Returns audit_buffer pointer on success or NULL on error.
1129 * Obtain an audit buffer. This routine does locking to obtain the
1130 * audit buffer, but then no locking is required for calls to
1131 * audit_log_*format. If the task (ctx) is a task that is currently in a
1132 * syscall, then the syscall is marked as auditable and an audit record
1133 * will be written at syscall exit. If there is no associated task, then
1134 * task context (ctx) should be NULL.
1136 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1139 struct audit_buffer *ab = NULL;
1141 unsigned int uninitialized_var(serial);
1143 unsigned long timeout_start = jiffies;
1145 if (audit_initialized != AUDIT_INITIALIZED)
1148 if (unlikely(audit_filter_type(type)))
1151 if (gfp_mask & __GFP_WAIT)
1154 reserve = 5; /* Allow atomic callers to go up to five
1155 entries over the normal backlog limit */
1157 while (audit_backlog_limit
1158 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1159 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1160 && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1162 /* Wait for auditd to drain the queue a little */
1163 DECLARE_WAITQUEUE(wait, current);
1164 set_current_state(TASK_INTERRUPTIBLE);
1165 add_wait_queue(&audit_backlog_wait, &wait);
1167 if (audit_backlog_limit &&
1168 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1169 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1171 __set_current_state(TASK_RUNNING);
1172 remove_wait_queue(&audit_backlog_wait, &wait);
1175 if (audit_rate_check() && printk_ratelimit())
1177 "audit: audit_backlog=%d > "
1178 "audit_backlog_limit=%d\n",
1179 skb_queue_len(&audit_skb_queue),
1180 audit_backlog_limit);
1181 audit_log_lost("backlog limit exceeded");
1182 audit_backlog_wait_time = audit_backlog_wait_overflow;
1183 wake_up(&audit_backlog_wait);
1187 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1189 audit_log_lost("out of memory in audit_log_start");
1193 audit_get_stamp(ab->ctx, &t, &serial);
1195 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1196 t.tv_sec, t.tv_nsec/1000000, serial);
1201 * audit_expand - expand skb in the audit buffer
1203 * @extra: space to add at tail of the skb
1205 * Returns 0 (no space) on failed expansion, or available space if
1208 static inline int audit_expand(struct audit_buffer *ab, int extra)
1210 struct sk_buff *skb = ab->skb;
1211 int oldtail = skb_tailroom(skb);
1212 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1213 int newtail = skb_tailroom(skb);
1216 audit_log_lost("out of memory in audit_expand");
1220 skb->truesize += newtail - oldtail;
1225 * Format an audit message into the audit buffer. If there isn't enough
1226 * room in the audit buffer, more room will be allocated and vsnprint
1227 * will be called a second time. Currently, we assume that a printk
1228 * can't format message larger than 1024 bytes, so we don't either.
1230 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1234 struct sk_buff *skb;
1242 avail = skb_tailroom(skb);
1244 avail = audit_expand(ab, AUDIT_BUFSIZ);
1248 va_copy(args2, args);
1249 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1251 /* The printk buffer is 1024 bytes long, so if we get
1252 * here and AUDIT_BUFSIZ is at least 1024, then we can
1253 * log everything that printk could have logged. */
1254 avail = audit_expand(ab,
1255 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1258 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1269 * audit_log_format - format a message into the audit buffer.
1271 * @fmt: format string
1272 * @...: optional parameters matching @fmt string
1274 * All the work is done in audit_log_vformat.
1276 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1282 va_start(args, fmt);
1283 audit_log_vformat(ab, fmt, args);
1288 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1289 * @ab: the audit_buffer
1290 * @buf: buffer to convert to hex
1291 * @len: length of @buf to be converted
1293 * No return value; failure to expand is silently ignored.
1295 * This function will take the passed buf and convert it into a string of
1296 * ascii hex digits. The new string is placed onto the skb.
1298 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1301 int i, avail, new_len;
1303 struct sk_buff *skb;
1304 static const unsigned char *hex = "0123456789ABCDEF";
1311 avail = skb_tailroom(skb);
1313 if (new_len >= avail) {
1314 /* Round the buffer request up to the next multiple */
1315 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1316 avail = audit_expand(ab, new_len);
1321 ptr = skb_tail_pointer(skb);
1322 for (i=0; i<len; i++) {
1323 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1324 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1327 skb_put(skb, len << 1); /* new string is twice the old string */
1331 * Format a string of no more than slen characters into the audit buffer,
1332 * enclosed in quote marks.
1334 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1339 struct sk_buff *skb;
1346 avail = skb_tailroom(skb);
1347 new_len = slen + 3; /* enclosing quotes + null terminator */
1348 if (new_len > avail) {
1349 avail = audit_expand(ab, new_len);
1353 ptr = skb_tail_pointer(skb);
1355 memcpy(ptr, string, slen);
1359 skb_put(skb, slen + 2); /* don't include null terminator */
1363 * audit_string_contains_control - does a string need to be logged in hex
1364 * @string: string to be checked
1365 * @len: max length of the string to check
1367 int audit_string_contains_control(const char *string, size_t len)
1369 const unsigned char *p;
1370 for (p = string; p < (const unsigned char *)string + len; p++) {
1371 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1378 * audit_log_n_untrustedstring - log a string that may contain random characters
1380 * @len: length of string (not including trailing null)
1381 * @string: string to be logged
1383 * This code will escape a string that is passed to it if the string
1384 * contains a control character, unprintable character, double quote mark,
1385 * or a space. Unescaped strings will start and end with a double quote mark.
1386 * Strings that are escaped are printed in hex (2 digits per char).
1388 * The caller specifies the number of characters in the string to log, which may
1389 * or may not be the entire string.
1391 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1394 if (audit_string_contains_control(string, len))
1395 audit_log_n_hex(ab, string, len);
1397 audit_log_n_string(ab, string, len);
1401 * audit_log_untrustedstring - log a string that may contain random characters
1403 * @string: string to be logged
1405 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1406 * determine string length.
1408 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1410 audit_log_n_untrustedstring(ab, string, strlen(string));
1413 /* This is a helper-function to print the escaped d_path */
1414 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1415 const struct path *path)
1420 audit_log_format(ab, "%s", prefix);
1422 /* We will allow 11 spaces for ' (deleted)' to be appended */
1423 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1425 audit_log_string(ab, "<no_memory>");
1428 p = d_path(path, pathname, PATH_MAX+11);
1429 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1430 /* FIXME: can we save some information here? */
1431 audit_log_string(ab, "<too_long>");
1433 audit_log_untrustedstring(ab, p);
1437 void audit_log_key(struct audit_buffer *ab, char *key)
1439 audit_log_format(ab, " key=");
1441 audit_log_untrustedstring(ab, key);
1443 audit_log_format(ab, "(null)");
1447 * audit_log_link_denied - report a link restriction denial
1448 * @operation: specific link opreation
1449 * @link: the path that triggered the restriction
1451 void audit_log_link_denied(const char *operation, struct path *link)
1453 struct audit_buffer *ab;
1455 ab = audit_log_start(current->audit_context, GFP_KERNEL,
1457 audit_log_format(ab, "op=%s action=denied", operation);
1458 audit_log_format(ab, " pid=%d comm=", current->pid);
1459 audit_log_untrustedstring(ab, current->comm);
1460 audit_log_d_path(ab, " path=", link);
1461 audit_log_format(ab, " dev=");
1462 audit_log_untrustedstring(ab, link->dentry->d_inode->i_sb->s_id);
1463 audit_log_format(ab, " ino=%lu", link->dentry->d_inode->i_ino);
1468 * audit_log_end - end one audit record
1469 * @ab: the audit_buffer
1471 * The netlink_* functions cannot be called inside an irq context, so
1472 * the audit buffer is placed on a queue and a tasklet is scheduled to
1473 * remove them from the queue outside the irq context. May be called in
1476 void audit_log_end(struct audit_buffer *ab)
1480 if (!audit_rate_check()) {
1481 audit_log_lost("rate limit exceeded");
1483 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1484 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1487 skb_queue_tail(&audit_skb_queue, ab->skb);
1488 wake_up_interruptible(&kauditd_wait);
1490 audit_printk_skb(ab->skb);
1494 audit_buffer_free(ab);
1498 * audit_log - Log an audit record
1499 * @ctx: audit context
1500 * @gfp_mask: type of allocation
1501 * @type: audit message type
1502 * @fmt: format string to use
1503 * @...: variable parameters matching the format string
1505 * This is a convenience function that calls audit_log_start,
1506 * audit_log_vformat, and audit_log_end. It may be called
1509 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1510 const char *fmt, ...)
1512 struct audit_buffer *ab;
1515 ab = audit_log_start(ctx, gfp_mask, type);
1517 va_start(args, fmt);
1518 audit_log_vformat(ab, fmt, args);
1524 #ifdef CONFIG_SECURITY
1526 * audit_log_secctx - Converts and logs SELinux context
1528 * @secid: security number
1530 * This is a helper function that calls security_secid_to_secctx to convert
1531 * secid to secctx and then adds the (converted) SELinux context to the audit
1532 * log by calling audit_log_format, thus also preventing leak of internal secid
1533 * to userspace. If secid cannot be converted audit_panic is called.
1535 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1540 if (security_secid_to_secctx(secid, &secctx, &len)) {
1541 audit_panic("Cannot convert secid to context");
1543 audit_log_format(ab, " obj=%s", secctx);
1544 security_release_secctx(secctx, len);
1547 EXPORT_SYMBOL(audit_log_secctx);
1550 EXPORT_SYMBOL(audit_log_start);
1551 EXPORT_SYMBOL(audit_log_end);
1552 EXPORT_SYMBOL(audit_log_format);
1553 EXPORT_SYMBOL(audit_log);