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>
52 #include <linux/kernel.h>
53 #include <linux/syscalls.h>
55 #include <linux/audit.h>
58 #include <net/netlink.h>
59 #include <linux/skbuff.h>
60 #ifdef CONFIG_SECURITY
61 #include <linux/security.h>
63 #include <net/netlink.h>
64 #include <linux/freezer.h>
65 #include <linux/tty.h>
66 #include <linux/pid_namespace.h>
70 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
71 * (Initialization happens after skb_init is called.) */
72 #define AUDIT_DISABLED -1
73 #define AUDIT_UNINITIALIZED 0
74 #define AUDIT_INITIALIZED 1
75 static int audit_initialized;
79 #define AUDIT_LOCKED 2
81 int audit_ever_enabled;
83 EXPORT_SYMBOL_GPL(audit_enabled);
85 /* Default state when kernel boots without any parameters. */
86 static int audit_default;
88 /* If auditing cannot proceed, audit_failure selects what happens. */
89 static int audit_failure = AUDIT_FAIL_PRINTK;
92 * If audit records are to be written to the netlink socket, audit_pid
93 * contains the pid of the auditd process and audit_nlk_portid contains
94 * the portid to use to send netlink messages to that process.
97 static int audit_nlk_portid;
99 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
100 * to that number per second. This prevents DoS attacks, but results in
101 * audit records being dropped. */
102 static int audit_rate_limit;
104 /* Number of outstanding audit_buffers allowed. */
105 static int audit_backlog_limit = 64;
106 static int audit_backlog_wait_time = 60 * HZ;
107 static int audit_backlog_wait_overflow = 0;
109 /* The identity of the user shutting down the audit system. */
110 kuid_t audit_sig_uid = INVALID_UID;
111 pid_t audit_sig_pid = -1;
112 u32 audit_sig_sid = 0;
114 /* Records can be lost in several ways:
115 0) [suppressed in audit_alloc]
116 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
117 2) out of memory in audit_log_move [alloc_skb]
118 3) suppressed due to audit_rate_limit
119 4) suppressed due to audit_backlog_limit
121 static atomic_t audit_lost = ATOMIC_INIT(0);
123 /* The netlink socket. */
124 static struct sock *audit_sock;
126 /* Hash for inode-based rules */
127 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
129 /* The audit_freelist is a list of pre-allocated audit buffers (if more
130 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
131 * being placed on the freelist). */
132 static DEFINE_SPINLOCK(audit_freelist_lock);
133 static int audit_freelist_count;
134 static LIST_HEAD(audit_freelist);
136 static struct sk_buff_head audit_skb_queue;
137 /* queue of skbs to send to auditd when/if it comes back */
138 static struct sk_buff_head audit_skb_hold_queue;
139 static struct task_struct *kauditd_task;
140 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
141 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
143 /* Serialize requests from userspace. */
144 DEFINE_MUTEX(audit_cmd_mutex);
146 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
147 * audit records. Since printk uses a 1024 byte buffer, this buffer
148 * should be at least that large. */
149 #define AUDIT_BUFSIZ 1024
151 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
152 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
153 #define AUDIT_MAXFREE (2*NR_CPUS)
155 /* The audit_buffer is used when formatting an audit record. The caller
156 * locks briefly to get the record off the freelist or to allocate the
157 * buffer, and locks briefly to send the buffer to the netlink layer or
158 * to place it on a transmit queue. Multiple audit_buffers can be in
159 * use simultaneously. */
160 struct audit_buffer {
161 struct list_head list;
162 struct sk_buff *skb; /* formatted skb ready to send */
163 struct audit_context *ctx; /* NULL or associated context */
172 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
175 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
176 nlh->nlmsg_pid = pid;
180 void audit_panic(const char *message)
182 switch (audit_failure)
184 case AUDIT_FAIL_SILENT:
186 case AUDIT_FAIL_PRINTK:
187 if (printk_ratelimit())
188 printk(KERN_ERR "audit: %s\n", message);
190 case AUDIT_FAIL_PANIC:
191 /* test audit_pid since printk is always losey, why bother? */
193 panic("audit: %s\n", message);
198 static inline int audit_rate_check(void)
200 static unsigned long last_check = 0;
201 static int messages = 0;
202 static DEFINE_SPINLOCK(lock);
205 unsigned long elapsed;
208 if (!audit_rate_limit) return 1;
210 spin_lock_irqsave(&lock, flags);
211 if (++messages < audit_rate_limit) {
215 elapsed = now - last_check;
222 spin_unlock_irqrestore(&lock, flags);
228 * audit_log_lost - conditionally log lost audit message event
229 * @message: the message stating reason for lost audit message
231 * Emit at least 1 message per second, even if audit_rate_check is
233 * Always increment the lost messages counter.
235 void audit_log_lost(const char *message)
237 static unsigned long last_msg = 0;
238 static DEFINE_SPINLOCK(lock);
243 atomic_inc(&audit_lost);
245 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
248 spin_lock_irqsave(&lock, flags);
250 if (now - last_msg > HZ) {
254 spin_unlock_irqrestore(&lock, flags);
258 if (printk_ratelimit())
260 "audit: audit_lost=%d audit_rate_limit=%d "
261 "audit_backlog_limit=%d\n",
262 atomic_read(&audit_lost),
264 audit_backlog_limit);
265 audit_panic(message);
269 static int audit_log_config_change(char *function_name, int new, int old,
272 struct audit_buffer *ab;
275 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
278 audit_log_format(ab, "%s=%d old=%d", function_name, new, old);
279 audit_log_session_info(ab);
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 uid_t uid = from_kuid(&init_user_ns, current_uid());
616 if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
621 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
624 audit_log_format(*ab, "pid=%d uid=%u", task_tgid_vnr(current), uid);
625 audit_log_session_info(*ab);
626 audit_log_task_context(*ab);
631 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
635 struct audit_status *status_get, status_set;
637 struct audit_buffer *ab;
638 u16 msg_type = nlh->nlmsg_type;
639 struct audit_sig_info *sig_data;
643 err = audit_netlink_ok(skb, msg_type);
647 /* As soon as there's any sign of userspace auditd,
648 * start kauditd to talk to it */
650 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
651 if (IS_ERR(kauditd_task)) {
652 err = PTR_ERR(kauditd_task);
657 seq = nlh->nlmsg_seq;
658 data = nlmsg_data(nlh);
663 status_set.enabled = audit_enabled;
664 status_set.failure = audit_failure;
665 status_set.pid = audit_pid;
666 status_set.rate_limit = audit_rate_limit;
667 status_set.backlog_limit = audit_backlog_limit;
668 status_set.lost = atomic_read(&audit_lost);
669 status_set.backlog = skb_queue_len(&audit_skb_queue);
670 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
671 &status_set, sizeof(status_set));
674 if (nlmsg_len(nlh) < sizeof(struct audit_status))
676 status_get = (struct audit_status *)data;
677 if (status_get->mask & AUDIT_STATUS_ENABLED) {
678 err = audit_set_enabled(status_get->enabled);
682 if (status_get->mask & AUDIT_STATUS_FAILURE) {
683 err = audit_set_failure(status_get->failure);
687 if (status_get->mask & AUDIT_STATUS_PID) {
688 int new_pid = status_get->pid;
690 if (audit_enabled != AUDIT_OFF)
691 audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
693 audit_nlk_portid = NETLINK_CB(skb).portid;
695 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
696 err = audit_set_rate_limit(status_get->rate_limit);
700 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
701 err = audit_set_backlog_limit(status_get->backlog_limit);
704 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
705 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
706 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
709 err = audit_filter_user(msg_type);
712 if (msg_type == AUDIT_USER_TTY) {
713 err = tty_audit_push_current();
717 audit_log_common_recv_msg(&ab, msg_type);
718 if (msg_type != AUDIT_USER_TTY)
719 audit_log_format(ab, " msg='%.1024s'",
724 audit_log_format(ab, " data=");
725 size = nlmsg_len(nlh);
727 ((unsigned char *)data)[size - 1] == '\0')
729 audit_log_n_untrustedstring(ab, data, size);
731 audit_set_pid(ab, NETLINK_CB(skb).portid);
737 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
739 if (audit_enabled == AUDIT_LOCKED) {
740 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
741 audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
746 case AUDIT_LIST_RULES:
747 err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
748 seq, data, nlmsg_len(nlh));
752 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
753 audit_log_format(ab, " op=trim res=1");
756 case AUDIT_MAKE_EQUIV: {
759 size_t msglen = nlmsg_len(nlh);
763 if (msglen < 2 * sizeof(u32))
765 memcpy(sizes, bufp, 2 * sizeof(u32));
766 bufp += 2 * sizeof(u32);
767 msglen -= 2 * sizeof(u32);
768 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
773 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
779 /* OK, here comes... */
780 err = audit_tag_tree(old, new);
782 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
784 audit_log_format(ab, " op=make_equiv old=");
785 audit_log_untrustedstring(ab, old);
786 audit_log_format(ab, " new=");
787 audit_log_untrustedstring(ab, new);
788 audit_log_format(ab, " res=%d", !err);
794 case AUDIT_SIGNAL_INFO:
797 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
801 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
804 security_release_secctx(ctx, len);
807 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
808 sig_data->pid = audit_sig_pid;
810 memcpy(sig_data->ctx, ctx, len);
811 security_release_secctx(ctx, len);
813 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO,
814 0, 0, sig_data, sizeof(*sig_data) + len);
817 case AUDIT_TTY_GET: {
818 struct audit_tty_status s;
819 struct task_struct *tsk = current;
821 spin_lock(&tsk->sighand->siglock);
822 s.enabled = tsk->signal->audit_tty != 0;
823 s.log_passwd = tsk->signal->audit_tty_log_passwd;
824 spin_unlock(&tsk->sighand->siglock);
826 audit_send_reply(NETLINK_CB(skb).portid, seq,
827 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
830 case AUDIT_TTY_SET: {
831 struct audit_tty_status s;
832 struct task_struct *tsk = current;
834 memset(&s, 0, sizeof(s));
835 /* guard against past and future API changes */
836 memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
837 if ((s.enabled != 0 && s.enabled != 1) ||
838 (s.log_passwd != 0 && s.log_passwd != 1))
841 spin_lock(&tsk->sighand->siglock);
842 tsk->signal->audit_tty = s.enabled;
843 tsk->signal->audit_tty_log_passwd = s.log_passwd;
844 spin_unlock(&tsk->sighand->siglock);
852 return err < 0 ? err : 0;
856 * Get message from skb. Each message is processed by audit_receive_msg.
857 * Malformed skbs with wrong length are discarded silently.
859 static void audit_receive_skb(struct sk_buff *skb)
861 struct nlmsghdr *nlh;
863 * len MUST be signed for nlmsg_next to be able to dec it below 0
864 * if the nlmsg_len was not aligned
869 nlh = nlmsg_hdr(skb);
872 while (nlmsg_ok(nlh, len)) {
873 err = audit_receive_msg(skb, nlh);
874 /* if err or if this message says it wants a response */
875 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
876 netlink_ack(skb, nlh, err);
878 nlh = nlmsg_next(nlh, &len);
882 /* Receive messages from netlink socket. */
883 static void audit_receive(struct sk_buff *skb)
885 mutex_lock(&audit_cmd_mutex);
886 audit_receive_skb(skb);
887 mutex_unlock(&audit_cmd_mutex);
890 /* Initialize audit support at boot time. */
891 static int __init audit_init(void)
894 struct netlink_kernel_cfg cfg = {
895 .input = audit_receive,
898 if (audit_initialized == AUDIT_DISABLED)
901 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
902 audit_default ? "enabled" : "disabled");
903 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
905 audit_panic("cannot initialize netlink socket");
907 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
909 skb_queue_head_init(&audit_skb_queue);
910 skb_queue_head_init(&audit_skb_hold_queue);
911 audit_initialized = AUDIT_INITIALIZED;
912 audit_enabled = audit_default;
913 audit_ever_enabled |= !!audit_default;
915 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
917 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
918 INIT_LIST_HEAD(&audit_inode_hash[i]);
922 __initcall(audit_init);
924 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
925 static int __init audit_enable(char *str)
927 audit_default = !!simple_strtol(str, NULL, 0);
929 audit_initialized = AUDIT_DISABLED;
931 printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
933 if (audit_initialized == AUDIT_INITIALIZED) {
934 audit_enabled = audit_default;
935 audit_ever_enabled |= !!audit_default;
936 } else if (audit_initialized == AUDIT_UNINITIALIZED) {
937 printk(" (after initialization)");
939 printk(" (until reboot)");
946 __setup("audit=", audit_enable);
948 static void audit_buffer_free(struct audit_buffer *ab)
958 spin_lock_irqsave(&audit_freelist_lock, flags);
959 if (audit_freelist_count > AUDIT_MAXFREE)
962 audit_freelist_count++;
963 list_add(&ab->list, &audit_freelist);
965 spin_unlock_irqrestore(&audit_freelist_lock, flags);
968 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
969 gfp_t gfp_mask, int type)
972 struct audit_buffer *ab = NULL;
973 struct nlmsghdr *nlh;
975 spin_lock_irqsave(&audit_freelist_lock, flags);
976 if (!list_empty(&audit_freelist)) {
977 ab = list_entry(audit_freelist.next,
978 struct audit_buffer, list);
980 --audit_freelist_count;
982 spin_unlock_irqrestore(&audit_freelist_lock, flags);
985 ab = kmalloc(sizeof(*ab), gfp_mask);
991 ab->gfp_mask = gfp_mask;
993 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
997 nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1007 audit_buffer_free(ab);
1012 * audit_serial - compute a serial number for the audit record
1014 * Compute a serial number for the audit record. Audit records are
1015 * written to user-space as soon as they are generated, so a complete
1016 * audit record may be written in several pieces. The timestamp of the
1017 * record and this serial number are used by the user-space tools to
1018 * determine which pieces belong to the same audit record. The
1019 * (timestamp,serial) tuple is unique for each syscall and is live from
1020 * syscall entry to syscall exit.
1022 * NOTE: Another possibility is to store the formatted records off the
1023 * audit context (for those records that have a context), and emit them
1024 * all at syscall exit. However, this could delay the reporting of
1025 * significant errors until syscall exit (or never, if the system
1028 unsigned int audit_serial(void)
1030 static DEFINE_SPINLOCK(serial_lock);
1031 static unsigned int serial = 0;
1033 unsigned long flags;
1036 spin_lock_irqsave(&serial_lock, flags);
1039 } while (unlikely(!ret));
1040 spin_unlock_irqrestore(&serial_lock, flags);
1045 static inline void audit_get_stamp(struct audit_context *ctx,
1046 struct timespec *t, unsigned int *serial)
1048 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1050 *serial = audit_serial();
1055 * Wait for auditd to drain the queue a little
1057 static void wait_for_auditd(unsigned long sleep_time)
1059 DECLARE_WAITQUEUE(wait, current);
1060 set_current_state(TASK_UNINTERRUPTIBLE);
1061 add_wait_queue(&audit_backlog_wait, &wait);
1063 if (audit_backlog_limit &&
1064 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1065 schedule_timeout(sleep_time);
1067 __set_current_state(TASK_RUNNING);
1068 remove_wait_queue(&audit_backlog_wait, &wait);
1071 /* Obtain an audit buffer. This routine does locking to obtain the
1072 * audit buffer, but then no locking is required for calls to
1073 * audit_log_*format. If the tsk is a task that is currently in a
1074 * syscall, then the syscall is marked as auditable and an audit record
1075 * will be written at syscall exit. If there is no associated task, tsk
1076 * should be NULL. */
1079 * audit_log_start - obtain an audit buffer
1080 * @ctx: audit_context (may be NULL)
1081 * @gfp_mask: type of allocation
1082 * @type: audit message type
1084 * Returns audit_buffer pointer on success or NULL on error.
1086 * Obtain an audit buffer. This routine does locking to obtain the
1087 * audit buffer, but then no locking is required for calls to
1088 * audit_log_*format. If the task (ctx) is a task that is currently in a
1089 * syscall, then the syscall is marked as auditable and an audit record
1090 * will be written at syscall exit. If there is no associated task, then
1091 * task context (ctx) should be NULL.
1093 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1096 struct audit_buffer *ab = NULL;
1098 unsigned int uninitialized_var(serial);
1100 unsigned long timeout_start = jiffies;
1102 if (audit_initialized != AUDIT_INITIALIZED)
1105 if (unlikely(audit_filter_type(type)))
1108 if (gfp_mask & __GFP_WAIT)
1111 reserve = 5; /* Allow atomic callers to go up to five
1112 entries over the normal backlog limit */
1114 while (audit_backlog_limit
1115 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1116 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
1117 unsigned long sleep_time;
1119 sleep_time = timeout_start + audit_backlog_wait_time -
1121 if ((long)sleep_time > 0) {
1122 wait_for_auditd(sleep_time);
1126 if (audit_rate_check() && printk_ratelimit())
1128 "audit: audit_backlog=%d > "
1129 "audit_backlog_limit=%d\n",
1130 skb_queue_len(&audit_skb_queue),
1131 audit_backlog_limit);
1132 audit_log_lost("backlog limit exceeded");
1133 audit_backlog_wait_time = audit_backlog_wait_overflow;
1134 wake_up(&audit_backlog_wait);
1138 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1140 audit_log_lost("out of memory in audit_log_start");
1144 audit_get_stamp(ab->ctx, &t, &serial);
1146 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1147 t.tv_sec, t.tv_nsec/1000000, serial);
1152 * audit_expand - expand skb in the audit buffer
1154 * @extra: space to add at tail of the skb
1156 * Returns 0 (no space) on failed expansion, or available space if
1159 static inline int audit_expand(struct audit_buffer *ab, int extra)
1161 struct sk_buff *skb = ab->skb;
1162 int oldtail = skb_tailroom(skb);
1163 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1164 int newtail = skb_tailroom(skb);
1167 audit_log_lost("out of memory in audit_expand");
1171 skb->truesize += newtail - oldtail;
1176 * Format an audit message into the audit buffer. If there isn't enough
1177 * room in the audit buffer, more room will be allocated and vsnprint
1178 * will be called a second time. Currently, we assume that a printk
1179 * can't format message larger than 1024 bytes, so we don't either.
1181 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1185 struct sk_buff *skb;
1193 avail = skb_tailroom(skb);
1195 avail = audit_expand(ab, AUDIT_BUFSIZ);
1199 va_copy(args2, args);
1200 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1202 /* The printk buffer is 1024 bytes long, so if we get
1203 * here and AUDIT_BUFSIZ is at least 1024, then we can
1204 * log everything that printk could have logged. */
1205 avail = audit_expand(ab,
1206 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1209 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1220 * audit_log_format - format a message into the audit buffer.
1222 * @fmt: format string
1223 * @...: optional parameters matching @fmt string
1225 * All the work is done in audit_log_vformat.
1227 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1233 va_start(args, fmt);
1234 audit_log_vformat(ab, fmt, args);
1239 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1240 * @ab: the audit_buffer
1241 * @buf: buffer to convert to hex
1242 * @len: length of @buf to be converted
1244 * No return value; failure to expand is silently ignored.
1246 * This function will take the passed buf and convert it into a string of
1247 * ascii hex digits. The new string is placed onto the skb.
1249 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1252 int i, avail, new_len;
1254 struct sk_buff *skb;
1255 static const unsigned char *hex = "0123456789ABCDEF";
1262 avail = skb_tailroom(skb);
1264 if (new_len >= avail) {
1265 /* Round the buffer request up to the next multiple */
1266 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1267 avail = audit_expand(ab, new_len);
1272 ptr = skb_tail_pointer(skb);
1273 for (i=0; i<len; i++) {
1274 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1275 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1278 skb_put(skb, len << 1); /* new string is twice the old string */
1282 * Format a string of no more than slen characters into the audit buffer,
1283 * enclosed in quote marks.
1285 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1290 struct sk_buff *skb;
1297 avail = skb_tailroom(skb);
1298 new_len = slen + 3; /* enclosing quotes + null terminator */
1299 if (new_len > avail) {
1300 avail = audit_expand(ab, new_len);
1304 ptr = skb_tail_pointer(skb);
1306 memcpy(ptr, string, slen);
1310 skb_put(skb, slen + 2); /* don't include null terminator */
1314 * audit_string_contains_control - does a string need to be logged in hex
1315 * @string: string to be checked
1316 * @len: max length of the string to check
1318 int audit_string_contains_control(const char *string, size_t len)
1320 const unsigned char *p;
1321 for (p = string; p < (const unsigned char *)string + len; p++) {
1322 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1329 * audit_log_n_untrustedstring - log a string that may contain random characters
1331 * @len: length of string (not including trailing null)
1332 * @string: string to be logged
1334 * This code will escape a string that is passed to it if the string
1335 * contains a control character, unprintable character, double quote mark,
1336 * or a space. Unescaped strings will start and end with a double quote mark.
1337 * Strings that are escaped are printed in hex (2 digits per char).
1339 * The caller specifies the number of characters in the string to log, which may
1340 * or may not be the entire string.
1342 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1345 if (audit_string_contains_control(string, len))
1346 audit_log_n_hex(ab, string, len);
1348 audit_log_n_string(ab, string, len);
1352 * audit_log_untrustedstring - log a string that may contain random characters
1354 * @string: string to be logged
1356 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1357 * determine string length.
1359 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1361 audit_log_n_untrustedstring(ab, string, strlen(string));
1364 /* This is a helper-function to print the escaped d_path */
1365 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1366 const struct path *path)
1371 audit_log_format(ab, "%s", prefix);
1373 /* We will allow 11 spaces for ' (deleted)' to be appended */
1374 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1376 audit_log_string(ab, "<no_memory>");
1379 p = d_path(path, pathname, PATH_MAX+11);
1380 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1381 /* FIXME: can we save some information here? */
1382 audit_log_string(ab, "<too_long>");
1384 audit_log_untrustedstring(ab, p);
1388 void audit_log_session_info(struct audit_buffer *ab)
1390 u32 sessionid = audit_get_sessionid(current);
1391 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1393 audit_log_format(ab, " auid=%u ses=%u\n", auid, sessionid);
1396 void audit_log_key(struct audit_buffer *ab, char *key)
1398 audit_log_format(ab, " key=");
1400 audit_log_untrustedstring(ab, key);
1402 audit_log_format(ab, "(null)");
1405 void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1409 audit_log_format(ab, " %s=", prefix);
1410 CAP_FOR_EACH_U32(i) {
1411 audit_log_format(ab, "%08x",
1412 cap->cap[(_KERNEL_CAPABILITY_U32S-1) - i]);
1416 void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1418 kernel_cap_t *perm = &name->fcap.permitted;
1419 kernel_cap_t *inh = &name->fcap.inheritable;
1422 if (!cap_isclear(*perm)) {
1423 audit_log_cap(ab, "cap_fp", perm);
1426 if (!cap_isclear(*inh)) {
1427 audit_log_cap(ab, "cap_fi", inh);
1432 audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1433 name->fcap.fE, name->fcap_ver);
1436 static inline int audit_copy_fcaps(struct audit_names *name,
1437 const struct dentry *dentry)
1439 struct cpu_vfs_cap_data caps;
1445 rc = get_vfs_caps_from_disk(dentry, &caps);
1449 name->fcap.permitted = caps.permitted;
1450 name->fcap.inheritable = caps.inheritable;
1451 name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1452 name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1453 VFS_CAP_REVISION_SHIFT;
1458 /* Copy inode data into an audit_names. */
1459 void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1460 const struct inode *inode)
1462 name->ino = inode->i_ino;
1463 name->dev = inode->i_sb->s_dev;
1464 name->mode = inode->i_mode;
1465 name->uid = inode->i_uid;
1466 name->gid = inode->i_gid;
1467 name->rdev = inode->i_rdev;
1468 security_inode_getsecid(inode, &name->osid);
1469 audit_copy_fcaps(name, dentry);
1473 * audit_log_name - produce AUDIT_PATH record from struct audit_names
1474 * @context: audit_context for the task
1475 * @n: audit_names structure with reportable details
1476 * @path: optional path to report instead of audit_names->name
1477 * @record_num: record number to report when handling a list of names
1478 * @call_panic: optional pointer to int that will be updated if secid fails
1480 void audit_log_name(struct audit_context *context, struct audit_names *n,
1481 struct path *path, int record_num, int *call_panic)
1483 struct audit_buffer *ab;
1484 ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1488 audit_log_format(ab, "item=%d", record_num);
1491 audit_log_d_path(ab, " name=", path);
1493 switch (n->name_len) {
1494 case AUDIT_NAME_FULL:
1495 /* log the full path */
1496 audit_log_format(ab, " name=");
1497 audit_log_untrustedstring(ab, n->name->name);
1500 /* name was specified as a relative path and the
1501 * directory component is the cwd */
1502 audit_log_d_path(ab, " name=", &context->pwd);
1505 /* log the name's directory component */
1506 audit_log_format(ab, " name=");
1507 audit_log_n_untrustedstring(ab, n->name->name,
1511 audit_log_format(ab, " name=(null)");
1513 if (n->ino != (unsigned long)-1) {
1514 audit_log_format(ab, " inode=%lu"
1515 " dev=%02x:%02x mode=%#ho"
1516 " ouid=%u ogid=%u rdev=%02x:%02x",
1521 from_kuid(&init_user_ns, n->uid),
1522 from_kgid(&init_user_ns, n->gid),
1529 if (security_secid_to_secctx(
1530 n->osid, &ctx, &len)) {
1531 audit_log_format(ab, " osid=%u", n->osid);
1535 audit_log_format(ab, " obj=%s", ctx);
1536 security_release_secctx(ctx, len);
1540 /* log the audit_names record type */
1541 audit_log_format(ab, " nametype=");
1543 case AUDIT_TYPE_NORMAL:
1544 audit_log_format(ab, "NORMAL");
1546 case AUDIT_TYPE_PARENT:
1547 audit_log_format(ab, "PARENT");
1549 case AUDIT_TYPE_CHILD_DELETE:
1550 audit_log_format(ab, "DELETE");
1552 case AUDIT_TYPE_CHILD_CREATE:
1553 audit_log_format(ab, "CREATE");
1556 audit_log_format(ab, "UNKNOWN");
1560 audit_log_fcaps(ab, n);
1564 int audit_log_task_context(struct audit_buffer *ab)
1571 security_task_getsecid(current, &sid);
1575 error = security_secid_to_secctx(sid, &ctx, &len);
1577 if (error != -EINVAL)
1582 audit_log_format(ab, " subj=%s", ctx);
1583 security_release_secctx(ctx, len);
1587 audit_panic("error in audit_log_task_context");
1590 EXPORT_SYMBOL(audit_log_task_context);
1592 void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
1594 const struct cred *cred;
1595 char name[sizeof(tsk->comm)];
1596 struct mm_struct *mm = tsk->mm;
1602 /* tsk == current */
1603 cred = current_cred();
1605 spin_lock_irq(&tsk->sighand->siglock);
1606 if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
1607 tty = tsk->signal->tty->name;
1610 spin_unlock_irq(&tsk->sighand->siglock);
1612 audit_log_format(ab,
1613 " ppid=%ld pid=%d auid=%u uid=%u gid=%u"
1614 " euid=%u suid=%u fsuid=%u"
1615 " egid=%u sgid=%u fsgid=%u ses=%u tty=%s",
1618 from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
1619 from_kuid(&init_user_ns, cred->uid),
1620 from_kgid(&init_user_ns, cred->gid),
1621 from_kuid(&init_user_ns, cred->euid),
1622 from_kuid(&init_user_ns, cred->suid),
1623 from_kuid(&init_user_ns, cred->fsuid),
1624 from_kgid(&init_user_ns, cred->egid),
1625 from_kgid(&init_user_ns, cred->sgid),
1626 from_kgid(&init_user_ns, cred->fsgid),
1627 audit_get_sessionid(tsk), tty);
1629 get_task_comm(name, tsk);
1630 audit_log_format(ab, " comm=");
1631 audit_log_untrustedstring(ab, name);
1634 down_read(&mm->mmap_sem);
1636 audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
1637 up_read(&mm->mmap_sem);
1639 audit_log_task_context(ab);
1641 EXPORT_SYMBOL(audit_log_task_info);
1644 * audit_log_link_denied - report a link restriction denial
1645 * @operation: specific link opreation
1646 * @link: the path that triggered the restriction
1648 void audit_log_link_denied(const char *operation, struct path *link)
1650 struct audit_buffer *ab;
1651 struct audit_names *name;
1653 name = kzalloc(sizeof(*name), GFP_NOFS);
1657 /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
1658 ab = audit_log_start(current->audit_context, GFP_KERNEL,
1662 audit_log_format(ab, "op=%s", operation);
1663 audit_log_task_info(ab, current);
1664 audit_log_format(ab, " res=0");
1667 /* Generate AUDIT_PATH record with object. */
1668 name->type = AUDIT_TYPE_NORMAL;
1669 audit_copy_inode(name, link->dentry, link->dentry->d_inode);
1670 audit_log_name(current->audit_context, name, link, 0, NULL);
1676 * audit_log_end - end one audit record
1677 * @ab: the audit_buffer
1679 * The netlink_* functions cannot be called inside an irq context, so
1680 * the audit buffer is placed on a queue and a tasklet is scheduled to
1681 * remove them from the queue outside the irq context. May be called in
1684 void audit_log_end(struct audit_buffer *ab)
1688 if (!audit_rate_check()) {
1689 audit_log_lost("rate limit exceeded");
1691 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1692 nlh->nlmsg_len = ab->skb->len - NLMSG_HDRLEN;
1695 skb_queue_tail(&audit_skb_queue, ab->skb);
1696 wake_up_interruptible(&kauditd_wait);
1698 audit_printk_skb(ab->skb);
1702 audit_buffer_free(ab);
1706 * audit_log - Log an audit record
1707 * @ctx: audit context
1708 * @gfp_mask: type of allocation
1709 * @type: audit message type
1710 * @fmt: format string to use
1711 * @...: variable parameters matching the format string
1713 * This is a convenience function that calls audit_log_start,
1714 * audit_log_vformat, and audit_log_end. It may be called
1717 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1718 const char *fmt, ...)
1720 struct audit_buffer *ab;
1723 ab = audit_log_start(ctx, gfp_mask, type);
1725 va_start(args, fmt);
1726 audit_log_vformat(ab, fmt, args);
1732 #ifdef CONFIG_SECURITY
1734 * audit_log_secctx - Converts and logs SELinux context
1736 * @secid: security number
1738 * This is a helper function that calls security_secid_to_secctx to convert
1739 * secid to secctx and then adds the (converted) SELinux context to the audit
1740 * log by calling audit_log_format, thus also preventing leak of internal secid
1741 * to userspace. If secid cannot be converted audit_panic is called.
1743 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1748 if (security_secid_to_secctx(secid, &secctx, &len)) {
1749 audit_panic("Cannot convert secid to context");
1751 audit_log_format(ab, " obj=%s", secctx);
1752 security_release_secctx(secctx, len);
1755 EXPORT_SYMBOL(audit_log_secctx);
1758 EXPORT_SYMBOL(audit_log_start);
1759 EXPORT_SYMBOL(audit_log_end);
1760 EXPORT_SYMBOL(audit_log_format);
1761 EXPORT_SYMBOL(audit_log);