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_portid contains
92 * the portid to use to send netlink messages to that process.
95 static int audit_nlk_portid;
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 kuid_t audit_sig_uid = INVALID_UID;
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,
270 struct audit_buffer *ab;
272 u32 sessionid = audit_get_sessionid(current);
273 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
275 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
278 audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
279 old, auid, sessionid);
280 rc = audit_log_task_context(ab);
282 allow_changes = 0; /* Something weird, deny request */
283 audit_log_format(ab, " res=%d", allow_changes);
288 static int audit_do_config_change(char *function_name, int *to_change, int new)
290 int allow_changes, rc = 0, old = *to_change;
292 /* check if we are locked */
293 if (audit_enabled == AUDIT_LOCKED)
298 if (audit_enabled != AUDIT_OFF) {
299 rc = audit_log_config_change(function_name, new, old, allow_changes);
304 /* If we are allowed, make the change */
305 if (allow_changes == 1)
307 /* Not allowed, update reason */
313 static int audit_set_rate_limit(int limit)
315 return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
318 static int audit_set_backlog_limit(int limit)
320 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
323 static int audit_set_enabled(int state)
326 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
329 rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
331 audit_ever_enabled |= !!state;
336 static int audit_set_failure(int state)
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 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
348 * already have been sent via prink/syslog and so if these messages are dropped
349 * it is not a huge concern since we already passed the audit_log_lost()
350 * notification and stuff. This is just nice to get audit messages during
351 * boot before auditd is running or messages generated while auditd is stopped.
352 * This only holds messages is audit_default is set, aka booting with audit=1
353 * or building your kernel that way.
355 static void audit_hold_skb(struct sk_buff *skb)
358 skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
359 skb_queue_tail(&audit_skb_hold_queue, skb);
365 * For one reason or another this nlh isn't getting delivered to the userspace
366 * audit daemon, just send it to printk.
368 static void audit_printk_skb(struct sk_buff *skb)
370 struct nlmsghdr *nlh = nlmsg_hdr(skb);
371 char *data = nlmsg_data(nlh);
373 if (nlh->nlmsg_type != AUDIT_EOE) {
374 if (printk_ratelimit())
375 printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
377 audit_log_lost("printk limit exceeded\n");
383 static void kauditd_send_skb(struct sk_buff *skb)
386 /* take a reference in case we can't send it and we want to hold it */
388 err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
390 BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
391 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
392 audit_log_lost("auditd disappeared\n");
394 /* we might get lucky and get this in the next auditd */
397 /* drop the extra reference if sent ok */
402 * flush_hold_queue - empty the hold queue if auditd appears
404 * If auditd just started, drain the queue of messages already
405 * sent to syslog/printk. Remember loss here is ok. We already
406 * called audit_log_lost() if it didn't go out normally. so the
407 * race between the skb_dequeue and the next check for audit_pid
410 * If you ever find kauditd to be too slow we can get a perf win
411 * by doing our own locking and keeping better track if there
412 * are messages in this queue. I don't see the need now, but
413 * in 5 years when I want to play with this again I'll see this
414 * note and still have no friggin idea what i'm thinking today.
416 static void flush_hold_queue(void)
420 if (!audit_default || !audit_pid)
423 skb = skb_dequeue(&audit_skb_hold_queue);
427 while (skb && audit_pid) {
428 kauditd_send_skb(skb);
429 skb = skb_dequeue(&audit_skb_hold_queue);
433 * if auditd just disappeared but we
434 * dequeued an skb we need to drop ref
440 static int kauditd_thread(void *dummy)
443 while (!kthread_should_stop()) {
445 DECLARE_WAITQUEUE(wait, current);
449 skb = skb_dequeue(&audit_skb_queue);
450 wake_up(&audit_backlog_wait);
453 kauditd_send_skb(skb);
455 audit_printk_skb(skb);
458 set_current_state(TASK_INTERRUPTIBLE);
459 add_wait_queue(&kauditd_wait, &wait);
461 if (!skb_queue_len(&audit_skb_queue)) {
466 __set_current_state(TASK_RUNNING);
467 remove_wait_queue(&kauditd_wait, &wait);
472 int audit_send_list(void *_dest)
474 struct audit_netlink_list *dest = _dest;
478 /* wait for parent to finish and send an ACK */
479 mutex_lock(&audit_cmd_mutex);
480 mutex_unlock(&audit_cmd_mutex);
482 while ((skb = __skb_dequeue(&dest->q)) != NULL)
483 netlink_unicast(audit_sock, skb, pid, 0);
490 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
491 int multi, const void *payload, int size)
494 struct nlmsghdr *nlh;
496 int flags = multi ? NLM_F_MULTI : 0;
497 int t = done ? NLMSG_DONE : type;
499 skb = nlmsg_new(size, GFP_KERNEL);
503 nlh = nlmsg_put(skb, pid, seq, t, size, flags);
506 data = nlmsg_data(nlh);
507 memcpy(data, payload, size);
515 static int audit_send_reply_thread(void *arg)
517 struct audit_reply *reply = (struct audit_reply *)arg;
519 mutex_lock(&audit_cmd_mutex);
520 mutex_unlock(&audit_cmd_mutex);
522 /* Ignore failure. It'll only happen if the sender goes away,
523 because our timeout is set to infinite. */
524 netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
529 * audit_send_reply - send an audit reply message via netlink
530 * @pid: process id to send reply to
531 * @seq: sequence number
532 * @type: audit message type
533 * @done: done (last) flag
534 * @multi: multi-part message flag
535 * @payload: payload data
536 * @size: payload size
538 * Allocates an skb, builds the netlink message, and sends it to the pid.
539 * No failure notifications.
541 static void audit_send_reply(int pid, int seq, int type, int done, int multi,
542 const void *payload, int size)
545 struct task_struct *tsk;
546 struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
552 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
559 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
568 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
571 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
575 /* Only support the initial namespaces for now. */
576 if ((current_user_ns() != &init_user_ns) ||
577 (task_active_pid_ns(current) != &init_pid_ns))
587 case AUDIT_LIST_RULES:
590 case AUDIT_SIGNAL_INFO:
594 case AUDIT_MAKE_EQUIV:
595 if (!capable(CAP_AUDIT_CONTROL))
599 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
600 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
601 if (!capable(CAP_AUDIT_WRITE))
604 default: /* bad msg */
611 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
614 u32 sessionid = audit_get_sessionid(current);
615 uid_t uid = from_kuid(&init_user_ns, current_uid());
616 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
618 if (!audit_enabled) {
623 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
626 audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
627 task_tgid_vnr(current), uid, auid, sessionid);
628 audit_log_task_context(*ab);
633 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
637 struct audit_status *status_get, status_set;
639 struct audit_buffer *ab;
640 u16 msg_type = nlh->nlmsg_type;
641 struct audit_sig_info *sig_data;
645 err = audit_netlink_ok(skb, msg_type);
649 seq = nlh->nlmsg_seq;
650 data = nlmsg_data(nlh);
654 status_set.enabled = audit_enabled;
655 status_set.failure = audit_failure;
656 status_set.pid = audit_pid;
657 status_set.rate_limit = audit_rate_limit;
658 status_set.backlog_limit = audit_backlog_limit;
659 status_set.lost = atomic_read(&audit_lost);
660 status_set.backlog = skb_queue_len(&audit_skb_queue);
661 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
662 &status_set, sizeof(status_set));
665 if (nlh->nlmsg_len < sizeof(struct audit_status))
667 status_get = (struct audit_status *)data;
668 if (status_get->mask & AUDIT_STATUS_ENABLED) {
669 err = audit_set_enabled(status_get->enabled);
673 if (status_get->mask & AUDIT_STATUS_FAILURE) {
674 err = audit_set_failure(status_get->failure);
678 if (status_get->mask & AUDIT_STATUS_PID) {
679 int new_pid = status_get->pid;
681 if (audit_enabled != AUDIT_OFF)
682 audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
684 audit_nlk_portid = NETLINK_CB(skb).portid;
686 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
687 err = audit_set_rate_limit(status_get->rate_limit);
691 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
692 err = audit_set_backlog_limit(status_get->backlog_limit);
695 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
696 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
697 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
700 err = audit_filter_user(msg_type);
703 if (msg_type == AUDIT_USER_TTY) {
704 err = tty_audit_push_current();
708 audit_log_common_recv_msg(&ab, msg_type);
709 if (msg_type != AUDIT_USER_TTY)
710 audit_log_format(ab, " msg='%.1024s'",
715 audit_log_format(ab, " data=");
716 size = nlmsg_len(nlh);
718 ((unsigned char *)data)[size - 1] == '\0')
720 audit_log_n_untrustedstring(ab, data, size);
722 audit_set_pid(ab, NETLINK_CB(skb).portid);
728 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
730 if (audit_enabled == AUDIT_LOCKED) {
731 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
732 audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
737 case AUDIT_LIST_RULES:
738 err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
739 seq, data, nlmsg_len(nlh));
743 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
744 audit_log_format(ab, " op=trim res=1");
747 case AUDIT_MAKE_EQUIV: {
750 size_t msglen = nlmsg_len(nlh);
754 if (msglen < 2 * sizeof(u32))
756 memcpy(sizes, bufp, 2 * sizeof(u32));
757 bufp += 2 * sizeof(u32);
758 msglen -= 2 * sizeof(u32);
759 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
764 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
770 /* OK, here comes... */
771 err = audit_tag_tree(old, new);
773 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
775 audit_log_format(ab, " op=make_equiv old=");
776 audit_log_untrustedstring(ab, old);
777 audit_log_format(ab, " new=");
778 audit_log_untrustedstring(ab, new);
779 audit_log_format(ab, " res=%d", !err);
785 case AUDIT_SIGNAL_INFO:
788 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
792 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
795 security_release_secctx(ctx, len);
798 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
799 sig_data->pid = audit_sig_pid;
801 memcpy(sig_data->ctx, ctx, len);
802 security_release_secctx(ctx, len);
804 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO,
805 0, 0, sig_data, sizeof(*sig_data) + len);
808 case AUDIT_TTY_GET: {
809 struct audit_tty_status s;
810 struct task_struct *tsk = current;
812 spin_lock_irq(&tsk->sighand->siglock);
813 s.enabled = tsk->signal->audit_tty != 0;
814 spin_unlock_irq(&tsk->sighand->siglock);
816 audit_send_reply(NETLINK_CB(skb).portid, seq,
817 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
820 case AUDIT_TTY_SET: {
821 struct audit_tty_status *s;
822 struct task_struct *tsk = current;
824 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
827 if (s->enabled != 0 && s->enabled != 1)
830 spin_lock_irq(&tsk->sighand->siglock);
831 tsk->signal->audit_tty = s->enabled != 0;
832 spin_unlock_irq(&tsk->sighand->siglock);
840 return err < 0 ? err : 0;
844 * Get message from skb. Each message is processed by audit_receive_msg.
845 * Malformed skbs with wrong length are discarded silently.
847 static void audit_receive_skb(struct sk_buff *skb)
849 struct nlmsghdr *nlh;
851 * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
852 * if the nlmsg_len was not aligned
857 nlh = nlmsg_hdr(skb);
860 while (NLMSG_OK(nlh, len)) {
861 err = audit_receive_msg(skb, nlh);
862 /* if err or if this message says it wants a response */
863 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
864 netlink_ack(skb, nlh, err);
866 nlh = NLMSG_NEXT(nlh, len);
870 /* Receive messages from netlink socket. */
871 static void audit_receive(struct sk_buff *skb)
873 mutex_lock(&audit_cmd_mutex);
874 audit_receive_skb(skb);
875 mutex_unlock(&audit_cmd_mutex);
878 /* Initialize audit support at boot time. */
879 static int __init audit_init(void)
882 struct netlink_kernel_cfg cfg = {
883 .input = audit_receive,
886 if (audit_initialized == AUDIT_DISABLED)
889 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
890 audit_default ? "enabled" : "disabled");
891 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
893 audit_panic("cannot initialize netlink socket");
895 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
897 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
898 if (IS_ERR(kauditd_task))
899 return PTR_ERR(kauditd_task);
901 skb_queue_head_init(&audit_skb_queue);
902 skb_queue_head_init(&audit_skb_hold_queue);
903 audit_initialized = AUDIT_INITIALIZED;
904 audit_enabled = audit_default;
905 audit_ever_enabled |= !!audit_default;
907 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
909 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
910 INIT_LIST_HEAD(&audit_inode_hash[i]);
914 __initcall(audit_init);
916 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
917 static int __init audit_enable(char *str)
919 audit_default = !!simple_strtol(str, NULL, 0);
921 audit_initialized = AUDIT_DISABLED;
923 printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
925 if (audit_initialized == AUDIT_INITIALIZED) {
926 audit_enabled = audit_default;
927 audit_ever_enabled |= !!audit_default;
928 } else if (audit_initialized == AUDIT_UNINITIALIZED) {
929 printk(" (after initialization)");
931 printk(" (until reboot)");
938 __setup("audit=", audit_enable);
940 static void audit_buffer_free(struct audit_buffer *ab)
950 spin_lock_irqsave(&audit_freelist_lock, flags);
951 if (audit_freelist_count > AUDIT_MAXFREE)
954 audit_freelist_count++;
955 list_add(&ab->list, &audit_freelist);
957 spin_unlock_irqrestore(&audit_freelist_lock, flags);
960 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
961 gfp_t gfp_mask, int type)
964 struct audit_buffer *ab = NULL;
965 struct nlmsghdr *nlh;
967 spin_lock_irqsave(&audit_freelist_lock, flags);
968 if (!list_empty(&audit_freelist)) {
969 ab = list_entry(audit_freelist.next,
970 struct audit_buffer, list);
972 --audit_freelist_count;
974 spin_unlock_irqrestore(&audit_freelist_lock, flags);
977 ab = kmalloc(sizeof(*ab), gfp_mask);
983 ab->gfp_mask = gfp_mask;
985 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
989 nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
999 audit_buffer_free(ab);
1004 * audit_serial - compute a serial number for the audit record
1006 * Compute a serial number for the audit record. Audit records are
1007 * written to user-space as soon as they are generated, so a complete
1008 * audit record may be written in several pieces. The timestamp of the
1009 * record and this serial number are used by the user-space tools to
1010 * determine which pieces belong to the same audit record. The
1011 * (timestamp,serial) tuple is unique for each syscall and is live from
1012 * syscall entry to syscall exit.
1014 * NOTE: Another possibility is to store the formatted records off the
1015 * audit context (for those records that have a context), and emit them
1016 * all at syscall exit. However, this could delay the reporting of
1017 * significant errors until syscall exit (or never, if the system
1020 unsigned int audit_serial(void)
1022 static DEFINE_SPINLOCK(serial_lock);
1023 static unsigned int serial = 0;
1025 unsigned long flags;
1028 spin_lock_irqsave(&serial_lock, flags);
1031 } while (unlikely(!ret));
1032 spin_unlock_irqrestore(&serial_lock, flags);
1037 static inline void audit_get_stamp(struct audit_context *ctx,
1038 struct timespec *t, unsigned int *serial)
1040 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1042 *serial = audit_serial();
1047 * Wait for auditd to drain the queue a little
1049 static void wait_for_auditd(unsigned long sleep_time)
1051 DECLARE_WAITQUEUE(wait, current);
1052 set_current_state(TASK_INTERRUPTIBLE);
1053 add_wait_queue(&audit_backlog_wait, &wait);
1055 if (audit_backlog_limit &&
1056 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1057 schedule_timeout(sleep_time);
1059 __set_current_state(TASK_RUNNING);
1060 remove_wait_queue(&audit_backlog_wait, &wait);
1063 /* Obtain an audit buffer. This routine does locking to obtain the
1064 * audit buffer, but then no locking is required for calls to
1065 * audit_log_*format. If the tsk is a task that is currently in a
1066 * syscall, then the syscall is marked as auditable and an audit record
1067 * will be written at syscall exit. If there is no associated task, tsk
1068 * should be NULL. */
1071 * audit_log_start - obtain an audit buffer
1072 * @ctx: audit_context (may be NULL)
1073 * @gfp_mask: type of allocation
1074 * @type: audit message type
1076 * Returns audit_buffer pointer on success or NULL on error.
1078 * Obtain an audit buffer. This routine does locking to obtain the
1079 * audit buffer, but then no locking is required for calls to
1080 * audit_log_*format. If the task (ctx) is a task that is currently in a
1081 * syscall, then the syscall is marked as auditable and an audit record
1082 * will be written at syscall exit. If there is no associated task, then
1083 * task context (ctx) should be NULL.
1085 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1088 struct audit_buffer *ab = NULL;
1090 unsigned int uninitialized_var(serial);
1092 unsigned long timeout_start = jiffies;
1094 if (audit_initialized != AUDIT_INITIALIZED)
1097 if (unlikely(audit_filter_type(type)))
1100 if (gfp_mask & __GFP_WAIT)
1103 reserve = 5; /* Allow atomic callers to go up to five
1104 entries over the normal backlog limit */
1106 while (audit_backlog_limit
1107 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1108 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
1109 unsigned long sleep_time;
1111 sleep_time = timeout_start + audit_backlog_wait_time -
1113 if ((long)sleep_time > 0)
1114 wait_for_auditd(sleep_time);
1117 if (audit_rate_check() && printk_ratelimit())
1119 "audit: audit_backlog=%d > "
1120 "audit_backlog_limit=%d\n",
1121 skb_queue_len(&audit_skb_queue),
1122 audit_backlog_limit);
1123 audit_log_lost("backlog limit exceeded");
1124 audit_backlog_wait_time = audit_backlog_wait_overflow;
1125 wake_up(&audit_backlog_wait);
1129 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1131 audit_log_lost("out of memory in audit_log_start");
1135 audit_get_stamp(ab->ctx, &t, &serial);
1137 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1138 t.tv_sec, t.tv_nsec/1000000, serial);
1143 * audit_expand - expand skb in the audit buffer
1145 * @extra: space to add at tail of the skb
1147 * Returns 0 (no space) on failed expansion, or available space if
1150 static inline int audit_expand(struct audit_buffer *ab, int extra)
1152 struct sk_buff *skb = ab->skb;
1153 int oldtail = skb_tailroom(skb);
1154 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1155 int newtail = skb_tailroom(skb);
1158 audit_log_lost("out of memory in audit_expand");
1162 skb->truesize += newtail - oldtail;
1167 * Format an audit message into the audit buffer. If there isn't enough
1168 * room in the audit buffer, more room will be allocated and vsnprint
1169 * will be called a second time. Currently, we assume that a printk
1170 * can't format message larger than 1024 bytes, so we don't either.
1172 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1176 struct sk_buff *skb;
1184 avail = skb_tailroom(skb);
1186 avail = audit_expand(ab, AUDIT_BUFSIZ);
1190 va_copy(args2, args);
1191 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1193 /* The printk buffer is 1024 bytes long, so if we get
1194 * here and AUDIT_BUFSIZ is at least 1024, then we can
1195 * log everything that printk could have logged. */
1196 avail = audit_expand(ab,
1197 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1200 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1211 * audit_log_format - format a message into the audit buffer.
1213 * @fmt: format string
1214 * @...: optional parameters matching @fmt string
1216 * All the work is done in audit_log_vformat.
1218 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1224 va_start(args, fmt);
1225 audit_log_vformat(ab, fmt, args);
1230 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1231 * @ab: the audit_buffer
1232 * @buf: buffer to convert to hex
1233 * @len: length of @buf to be converted
1235 * No return value; failure to expand is silently ignored.
1237 * This function will take the passed buf and convert it into a string of
1238 * ascii hex digits. The new string is placed onto the skb.
1240 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1243 int i, avail, new_len;
1245 struct sk_buff *skb;
1246 static const unsigned char *hex = "0123456789ABCDEF";
1253 avail = skb_tailroom(skb);
1255 if (new_len >= avail) {
1256 /* Round the buffer request up to the next multiple */
1257 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1258 avail = audit_expand(ab, new_len);
1263 ptr = skb_tail_pointer(skb);
1264 for (i=0; i<len; i++) {
1265 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1266 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1269 skb_put(skb, len << 1); /* new string is twice the old string */
1273 * Format a string of no more than slen characters into the audit buffer,
1274 * enclosed in quote marks.
1276 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1281 struct sk_buff *skb;
1288 avail = skb_tailroom(skb);
1289 new_len = slen + 3; /* enclosing quotes + null terminator */
1290 if (new_len > avail) {
1291 avail = audit_expand(ab, new_len);
1295 ptr = skb_tail_pointer(skb);
1297 memcpy(ptr, string, slen);
1301 skb_put(skb, slen + 2); /* don't include null terminator */
1305 * audit_string_contains_control - does a string need to be logged in hex
1306 * @string: string to be checked
1307 * @len: max length of the string to check
1309 int audit_string_contains_control(const char *string, size_t len)
1311 const unsigned char *p;
1312 for (p = string; p < (const unsigned char *)string + len; p++) {
1313 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1320 * audit_log_n_untrustedstring - log a string that may contain random characters
1322 * @len: length of string (not including trailing null)
1323 * @string: string to be logged
1325 * This code will escape a string that is passed to it if the string
1326 * contains a control character, unprintable character, double quote mark,
1327 * or a space. Unescaped strings will start and end with a double quote mark.
1328 * Strings that are escaped are printed in hex (2 digits per char).
1330 * The caller specifies the number of characters in the string to log, which may
1331 * or may not be the entire string.
1333 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1336 if (audit_string_contains_control(string, len))
1337 audit_log_n_hex(ab, string, len);
1339 audit_log_n_string(ab, string, len);
1343 * audit_log_untrustedstring - log a string that may contain random characters
1345 * @string: string to be logged
1347 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1348 * determine string length.
1350 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1352 audit_log_n_untrustedstring(ab, string, strlen(string));
1355 /* This is a helper-function to print the escaped d_path */
1356 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1357 const struct path *path)
1362 audit_log_format(ab, "%s", prefix);
1364 /* We will allow 11 spaces for ' (deleted)' to be appended */
1365 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1367 audit_log_string(ab, "<no_memory>");
1370 p = d_path(path, pathname, PATH_MAX+11);
1371 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1372 /* FIXME: can we save some information here? */
1373 audit_log_string(ab, "<too_long>");
1375 audit_log_untrustedstring(ab, p);
1379 void audit_log_key(struct audit_buffer *ab, char *key)
1381 audit_log_format(ab, " key=");
1383 audit_log_untrustedstring(ab, key);
1385 audit_log_format(ab, "(null)");
1389 * audit_log_link_denied - report a link restriction denial
1390 * @operation: specific link opreation
1391 * @link: the path that triggered the restriction
1393 void audit_log_link_denied(const char *operation, struct path *link)
1395 struct audit_buffer *ab;
1397 ab = audit_log_start(current->audit_context, GFP_KERNEL,
1401 audit_log_format(ab, "op=%s action=denied", operation);
1402 audit_log_format(ab, " pid=%d comm=", current->pid);
1403 audit_log_untrustedstring(ab, current->comm);
1404 audit_log_d_path(ab, " path=", link);
1405 audit_log_format(ab, " dev=");
1406 audit_log_untrustedstring(ab, link->dentry->d_inode->i_sb->s_id);
1407 audit_log_format(ab, " ino=%lu", link->dentry->d_inode->i_ino);
1412 * audit_log_end - end one audit record
1413 * @ab: the audit_buffer
1415 * The netlink_* functions cannot be called inside an irq context, so
1416 * the audit buffer is placed on a queue and a tasklet is scheduled to
1417 * remove them from the queue outside the irq context. May be called in
1420 void audit_log_end(struct audit_buffer *ab)
1424 if (!audit_rate_check()) {
1425 audit_log_lost("rate limit exceeded");
1427 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1428 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1431 skb_queue_tail(&audit_skb_queue, ab->skb);
1432 wake_up_interruptible(&kauditd_wait);
1434 audit_printk_skb(ab->skb);
1438 audit_buffer_free(ab);
1442 * audit_log - Log an audit record
1443 * @ctx: audit context
1444 * @gfp_mask: type of allocation
1445 * @type: audit message type
1446 * @fmt: format string to use
1447 * @...: variable parameters matching the format string
1449 * This is a convenience function that calls audit_log_start,
1450 * audit_log_vformat, and audit_log_end. It may be called
1453 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1454 const char *fmt, ...)
1456 struct audit_buffer *ab;
1459 ab = audit_log_start(ctx, gfp_mask, type);
1461 va_start(args, fmt);
1462 audit_log_vformat(ab, fmt, args);
1468 #ifdef CONFIG_SECURITY
1470 * audit_log_secctx - Converts and logs SELinux context
1472 * @secid: security number
1474 * This is a helper function that calls security_secid_to_secctx to convert
1475 * secid to secctx and then adds the (converted) SELinux context to the audit
1476 * log by calling audit_log_format, thus also preventing leak of internal secid
1477 * to userspace. If secid cannot be converted audit_panic is called.
1479 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1484 if (security_secid_to_secctx(secid, &secctx, &len)) {
1485 audit_panic("Cannot convert secid to context");
1487 audit_log_format(ab, " obj=%s", secctx);
1488 security_release_secctx(secctx, len);
1491 EXPORT_SYMBOL(audit_log_secctx);
1494 EXPORT_SYMBOL(audit_log_start);
1495 EXPORT_SYMBOL(audit_log_end);
1496 EXPORT_SYMBOL(audit_log_format);
1497 EXPORT_SYMBOL(audit_log);