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 <linux/freezer.h>
64 #include <linux/tty.h>
65 #include <linux/pid_namespace.h>
69 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
70 * (Initialization happens after skb_init is called.) */
71 #define AUDIT_DISABLED -1
72 #define AUDIT_UNINITIALIZED 0
73 #define AUDIT_INITIALIZED 1
74 static int audit_initialized;
78 #define AUDIT_LOCKED 2
80 int audit_ever_enabled;
82 EXPORT_SYMBOL_GPL(audit_enabled);
84 /* Default state when kernel boots without any parameters. */
85 static int audit_default;
87 /* If auditing cannot proceed, audit_failure selects what happens. */
88 static int audit_failure = AUDIT_FAIL_PRINTK;
91 * If audit records are to be written to the netlink socket, audit_pid
92 * contains the pid of the auditd process and audit_nlk_portid contains
93 * the portid to use to send netlink messages to that process.
96 static int audit_nlk_portid;
98 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
99 * to that number per second. This prevents DoS attacks, but results in
100 * audit records being dropped. */
101 static int audit_rate_limit;
103 /* Number of outstanding audit_buffers allowed. */
104 static int audit_backlog_limit = 64;
105 static int audit_backlog_wait_time = 60 * HZ;
106 static int audit_backlog_wait_overflow = 0;
108 /* The identity of the user shutting down the audit system. */
109 kuid_t audit_sig_uid = INVALID_UID;
110 pid_t audit_sig_pid = -1;
111 u32 audit_sig_sid = 0;
113 /* Records can be lost in several ways:
114 0) [suppressed in audit_alloc]
115 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
116 2) out of memory in audit_log_move [alloc_skb]
117 3) suppressed due to audit_rate_limit
118 4) suppressed due to audit_backlog_limit
120 static atomic_t audit_lost = ATOMIC_INIT(0);
122 /* The netlink socket. */
123 static struct sock *audit_sock;
125 /* Hash for inode-based rules */
126 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
128 /* The audit_freelist is a list of pre-allocated audit buffers (if more
129 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
130 * being placed on the freelist). */
131 static DEFINE_SPINLOCK(audit_freelist_lock);
132 static int audit_freelist_count;
133 static LIST_HEAD(audit_freelist);
135 static struct sk_buff_head audit_skb_queue;
136 /* queue of skbs to send to auditd when/if it comes back */
137 static struct sk_buff_head audit_skb_hold_queue;
138 static struct task_struct *kauditd_task;
139 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
140 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
142 /* Serialize requests from userspace. */
143 DEFINE_MUTEX(audit_cmd_mutex);
145 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
146 * audit records. Since printk uses a 1024 byte buffer, this buffer
147 * should be at least that large. */
148 #define AUDIT_BUFSIZ 1024
150 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
151 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
152 #define AUDIT_MAXFREE (2*NR_CPUS)
154 /* The audit_buffer is used when formatting an audit record. The caller
155 * locks briefly to get the record off the freelist or to allocate the
156 * buffer, and locks briefly to send the buffer to the netlink layer or
157 * to place it on a transmit queue. Multiple audit_buffers can be in
158 * use simultaneously. */
159 struct audit_buffer {
160 struct list_head list;
161 struct sk_buff *skb; /* formatted skb ready to send */
162 struct audit_context *ctx; /* NULL or associated context */
171 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
174 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
175 nlh->nlmsg_pid = pid;
179 void audit_panic(const char *message)
181 switch (audit_failure)
183 case AUDIT_FAIL_SILENT:
185 case AUDIT_FAIL_PRINTK:
186 if (printk_ratelimit())
187 printk(KERN_ERR "audit: %s\n", message);
189 case AUDIT_FAIL_PANIC:
190 /* test audit_pid since printk is always losey, why bother? */
192 panic("audit: %s\n", message);
197 static inline int audit_rate_check(void)
199 static unsigned long last_check = 0;
200 static int messages = 0;
201 static DEFINE_SPINLOCK(lock);
204 unsigned long elapsed;
207 if (!audit_rate_limit) return 1;
209 spin_lock_irqsave(&lock, flags);
210 if (++messages < audit_rate_limit) {
214 elapsed = now - last_check;
221 spin_unlock_irqrestore(&lock, flags);
227 * audit_log_lost - conditionally log lost audit message event
228 * @message: the message stating reason for lost audit message
230 * Emit at least 1 message per second, even if audit_rate_check is
232 * Always increment the lost messages counter.
234 void audit_log_lost(const char *message)
236 static unsigned long last_msg = 0;
237 static DEFINE_SPINLOCK(lock);
242 atomic_inc(&audit_lost);
244 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
247 spin_lock_irqsave(&lock, flags);
249 if (now - last_msg > HZ) {
253 spin_unlock_irqrestore(&lock, flags);
257 if (printk_ratelimit())
259 "audit: audit_lost=%d audit_rate_limit=%d "
260 "audit_backlog_limit=%d\n",
261 atomic_read(&audit_lost),
263 audit_backlog_limit);
264 audit_panic(message);
268 static int audit_log_config_change(char *function_name, int new, int old,
271 struct audit_buffer *ab;
274 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
277 audit_log_format(ab, "%s=%d old=%d", function_name, new, old);
278 audit_log_session_info(ab);
279 rc = audit_log_task_context(ab);
281 allow_changes = 0; /* Something weird, deny request */
282 audit_log_format(ab, " res=%d", allow_changes);
287 static int audit_do_config_change(char *function_name, int *to_change, int new)
289 int allow_changes, rc = 0, old = *to_change;
291 /* check if we are locked */
292 if (audit_enabled == AUDIT_LOCKED)
297 if (audit_enabled != AUDIT_OFF) {
298 rc = audit_log_config_change(function_name, new, old, allow_changes);
303 /* If we are allowed, make the change */
304 if (allow_changes == 1)
306 /* Not allowed, update reason */
312 static int audit_set_rate_limit(int limit)
314 return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
317 static int audit_set_backlog_limit(int limit)
319 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
322 static int audit_set_enabled(int state)
325 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
328 rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
330 audit_ever_enabled |= !!state;
335 static int audit_set_failure(int state)
337 if (state != AUDIT_FAIL_SILENT
338 && state != AUDIT_FAIL_PRINTK
339 && state != AUDIT_FAIL_PANIC)
342 return audit_do_config_change("audit_failure", &audit_failure, state);
346 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
347 * already have been sent via prink/syslog and so if these messages are dropped
348 * it is not a huge concern since we already passed the audit_log_lost()
349 * notification and stuff. This is just nice to get audit messages during
350 * boot before auditd is running or messages generated while auditd is stopped.
351 * This only holds messages is audit_default is set, aka booting with audit=1
352 * or building your kernel that way.
354 static void audit_hold_skb(struct sk_buff *skb)
357 skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
358 skb_queue_tail(&audit_skb_hold_queue, skb);
364 * For one reason or another this nlh isn't getting delivered to the userspace
365 * audit daemon, just send it to printk.
367 static void audit_printk_skb(struct sk_buff *skb)
369 struct nlmsghdr *nlh = nlmsg_hdr(skb);
370 char *data = nlmsg_data(nlh);
372 if (nlh->nlmsg_type != AUDIT_EOE) {
373 if (printk_ratelimit())
374 printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
376 audit_log_lost("printk limit exceeded\n");
382 static void kauditd_send_skb(struct sk_buff *skb)
385 /* take a reference in case we can't send it and we want to hold it */
387 err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
389 BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
390 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
391 audit_log_lost("auditd disappeared\n");
393 /* we might get lucky and get this in the next auditd */
396 /* drop the extra reference if sent ok */
401 * flush_hold_queue - empty the hold queue if auditd appears
403 * If auditd just started, drain the queue of messages already
404 * sent to syslog/printk. Remember loss here is ok. We already
405 * called audit_log_lost() if it didn't go out normally. so the
406 * race between the skb_dequeue and the next check for audit_pid
409 * If you ever find kauditd to be too slow we can get a perf win
410 * by doing our own locking and keeping better track if there
411 * are messages in this queue. I don't see the need now, but
412 * in 5 years when I want to play with this again I'll see this
413 * note and still have no friggin idea what i'm thinking today.
415 static void flush_hold_queue(void)
419 if (!audit_default || !audit_pid)
422 skb = skb_dequeue(&audit_skb_hold_queue);
426 while (skb && audit_pid) {
427 kauditd_send_skb(skb);
428 skb = skb_dequeue(&audit_skb_hold_queue);
432 * if auditd just disappeared but we
433 * dequeued an skb we need to drop ref
439 static int kauditd_thread(void *dummy)
442 while (!kthread_should_stop()) {
444 DECLARE_WAITQUEUE(wait, current);
448 skb = skb_dequeue(&audit_skb_queue);
449 wake_up(&audit_backlog_wait);
452 kauditd_send_skb(skb);
454 audit_printk_skb(skb);
457 set_current_state(TASK_INTERRUPTIBLE);
458 add_wait_queue(&kauditd_wait, &wait);
460 if (!skb_queue_len(&audit_skb_queue)) {
465 __set_current_state(TASK_RUNNING);
466 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))
586 case AUDIT_LIST_RULES:
589 case AUDIT_SIGNAL_INFO:
593 case AUDIT_MAKE_EQUIV:
594 if (!capable(CAP_AUDIT_CONTROL))
598 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
599 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
600 if (!capable(CAP_AUDIT_WRITE))
603 default: /* bad msg */
610 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
613 uid_t uid = from_kuid(&init_user_ns, current_uid());
615 if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
620 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
623 audit_log_format(*ab, "pid=%d uid=%u", task_tgid_vnr(current), uid);
624 audit_log_session_info(*ab);
625 audit_log_task_context(*ab);
630 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
634 struct audit_status *status_get, status_set;
636 struct audit_buffer *ab;
637 u16 msg_type = nlh->nlmsg_type;
638 struct audit_sig_info *sig_data;
642 err = audit_netlink_ok(skb, msg_type);
646 /* As soon as there's any sign of userspace auditd,
647 * start kauditd to talk to it */
649 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
650 if (IS_ERR(kauditd_task)) {
651 err = PTR_ERR(kauditd_task);
656 seq = nlh->nlmsg_seq;
657 data = nlmsg_data(nlh);
661 status_set.enabled = audit_enabled;
662 status_set.failure = audit_failure;
663 status_set.pid = audit_pid;
664 status_set.rate_limit = audit_rate_limit;
665 status_set.backlog_limit = audit_backlog_limit;
666 status_set.lost = atomic_read(&audit_lost);
667 status_set.backlog = skb_queue_len(&audit_skb_queue);
668 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
669 &status_set, sizeof(status_set));
672 if (nlh->nlmsg_len < sizeof(struct audit_status))
674 status_get = (struct audit_status *)data;
675 if (status_get->mask & AUDIT_STATUS_ENABLED) {
676 err = audit_set_enabled(status_get->enabled);
680 if (status_get->mask & AUDIT_STATUS_FAILURE) {
681 err = audit_set_failure(status_get->failure);
685 if (status_get->mask & AUDIT_STATUS_PID) {
686 int new_pid = status_get->pid;
688 if (audit_enabled != AUDIT_OFF)
689 audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
691 audit_nlk_portid = NETLINK_CB(skb).portid;
693 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
694 err = audit_set_rate_limit(status_get->rate_limit);
698 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
699 err = audit_set_backlog_limit(status_get->backlog_limit);
702 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
703 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
704 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
707 err = audit_filter_user(msg_type);
710 if (msg_type == AUDIT_USER_TTY) {
711 err = tty_audit_push_current();
715 audit_log_common_recv_msg(&ab, msg_type);
716 if (msg_type != AUDIT_USER_TTY)
717 audit_log_format(ab, " msg='%.*s'",
718 AUDIT_MESSAGE_TEXT_MAX,
723 audit_log_format(ab, " data=");
724 size = nlmsg_len(nlh);
726 ((unsigned char *)data)[size - 1] == '\0')
728 audit_log_n_untrustedstring(ab, data, size);
730 audit_set_pid(ab, NETLINK_CB(skb).portid);
736 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
738 if (audit_enabled == AUDIT_LOCKED) {
739 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
740 audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
745 case AUDIT_LIST_RULES:
746 err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
747 seq, data, nlmsg_len(nlh));
751 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
752 audit_log_format(ab, " op=trim res=1");
755 case AUDIT_MAKE_EQUIV: {
758 size_t msglen = nlmsg_len(nlh);
762 if (msglen < 2 * sizeof(u32))
764 memcpy(sizes, bufp, 2 * sizeof(u32));
765 bufp += 2 * sizeof(u32);
766 msglen -= 2 * sizeof(u32);
767 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
772 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
778 /* OK, here comes... */
779 err = audit_tag_tree(old, new);
781 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
783 audit_log_format(ab, " op=make_equiv old=");
784 audit_log_untrustedstring(ab, old);
785 audit_log_format(ab, " new=");
786 audit_log_untrustedstring(ab, new);
787 audit_log_format(ab, " res=%d", !err);
793 case AUDIT_SIGNAL_INFO:
796 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
800 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
803 security_release_secctx(ctx, len);
806 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
807 sig_data->pid = audit_sig_pid;
809 memcpy(sig_data->ctx, ctx, len);
810 security_release_secctx(ctx, len);
812 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO,
813 0, 0, sig_data, sizeof(*sig_data) + len);
816 case AUDIT_TTY_GET: {
817 struct audit_tty_status s;
818 struct task_struct *tsk = current;
820 spin_lock(&tsk->sighand->siglock);
821 s.enabled = tsk->signal->audit_tty != 0;
822 s.log_passwd = tsk->signal->audit_tty_log_passwd;
823 spin_unlock(&tsk->sighand->siglock);
825 audit_send_reply(NETLINK_CB(skb).portid, seq,
826 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
829 case AUDIT_TTY_SET: {
830 struct audit_tty_status s;
831 struct task_struct *tsk = current;
833 memset(&s, 0, sizeof(s));
834 /* guard against past and future API changes */
835 memcpy(&s, data, min(sizeof(s), (size_t)nlh->nlmsg_len));
836 if ((s.enabled != 0 && s.enabled != 1) ||
837 (s.log_passwd != 0 && s.log_passwd != 1))
840 spin_lock(&tsk->sighand->siglock);
841 tsk->signal->audit_tty = s.enabled;
842 tsk->signal->audit_tty_log_passwd = s.log_passwd;
843 spin_unlock(&tsk->sighand->siglock);
851 return err < 0 ? err : 0;
855 * Get message from skb. Each message is processed by audit_receive_msg.
856 * Malformed skbs with wrong length are discarded silently.
858 static void audit_receive_skb(struct sk_buff *skb)
860 struct nlmsghdr *nlh;
862 * len MUST be signed for nlmsg_next to be able to dec it below 0
863 * if the nlmsg_len was not aligned
868 nlh = nlmsg_hdr(skb);
871 while (nlmsg_ok(nlh, len)) {
872 err = audit_receive_msg(skb, nlh);
873 /* if err or if this message says it wants a response */
874 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
875 netlink_ack(skb, nlh, err);
877 nlh = nlmsg_next(nlh, &len);
881 /* Receive messages from netlink socket. */
882 static void audit_receive(struct sk_buff *skb)
884 mutex_lock(&audit_cmd_mutex);
885 audit_receive_skb(skb);
886 mutex_unlock(&audit_cmd_mutex);
889 /* Initialize audit support at boot time. */
890 static int __init audit_init(void)
893 struct netlink_kernel_cfg cfg = {
894 .input = audit_receive,
897 if (audit_initialized == AUDIT_DISABLED)
900 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
901 audit_default ? "enabled" : "disabled");
902 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
904 audit_panic("cannot initialize netlink socket");
906 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
908 skb_queue_head_init(&audit_skb_queue);
909 skb_queue_head_init(&audit_skb_hold_queue);
910 audit_initialized = AUDIT_INITIALIZED;
911 audit_enabled = audit_default;
912 audit_ever_enabled |= !!audit_default;
914 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
916 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
917 INIT_LIST_HEAD(&audit_inode_hash[i]);
921 __initcall(audit_init);
923 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
924 static int __init audit_enable(char *str)
926 audit_default = !!simple_strtol(str, NULL, 0);
928 audit_initialized = AUDIT_DISABLED;
930 printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
932 if (audit_initialized == AUDIT_INITIALIZED) {
933 audit_enabled = audit_default;
934 audit_ever_enabled |= !!audit_default;
935 } else if (audit_initialized == AUDIT_UNINITIALIZED) {
936 printk(" (after initialization)");
938 printk(" (until reboot)");
945 __setup("audit=", audit_enable);
947 static void audit_buffer_free(struct audit_buffer *ab)
957 spin_lock_irqsave(&audit_freelist_lock, flags);
958 if (audit_freelist_count > AUDIT_MAXFREE)
961 audit_freelist_count++;
962 list_add(&ab->list, &audit_freelist);
964 spin_unlock_irqrestore(&audit_freelist_lock, flags);
967 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
968 gfp_t gfp_mask, int type)
971 struct audit_buffer *ab = NULL;
972 struct nlmsghdr *nlh;
974 spin_lock_irqsave(&audit_freelist_lock, flags);
975 if (!list_empty(&audit_freelist)) {
976 ab = list_entry(audit_freelist.next,
977 struct audit_buffer, list);
979 --audit_freelist_count;
981 spin_unlock_irqrestore(&audit_freelist_lock, flags);
984 ab = kmalloc(sizeof(*ab), gfp_mask);
990 ab->gfp_mask = gfp_mask;
992 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
996 nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1006 audit_buffer_free(ab);
1011 * audit_serial - compute a serial number for the audit record
1013 * Compute a serial number for the audit record. Audit records are
1014 * written to user-space as soon as they are generated, so a complete
1015 * audit record may be written in several pieces. The timestamp of the
1016 * record and this serial number are used by the user-space tools to
1017 * determine which pieces belong to the same audit record. The
1018 * (timestamp,serial) tuple is unique for each syscall and is live from
1019 * syscall entry to syscall exit.
1021 * NOTE: Another possibility is to store the formatted records off the
1022 * audit context (for those records that have a context), and emit them
1023 * all at syscall exit. However, this could delay the reporting of
1024 * significant errors until syscall exit (or never, if the system
1027 unsigned int audit_serial(void)
1029 static DEFINE_SPINLOCK(serial_lock);
1030 static unsigned int serial = 0;
1032 unsigned long flags;
1035 spin_lock_irqsave(&serial_lock, flags);
1038 } while (unlikely(!ret));
1039 spin_unlock_irqrestore(&serial_lock, flags);
1044 static inline void audit_get_stamp(struct audit_context *ctx,
1045 struct timespec *t, unsigned int *serial)
1047 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1049 *serial = audit_serial();
1054 * Wait for auditd to drain the queue a little
1056 static void wait_for_auditd(unsigned long sleep_time)
1058 DECLARE_WAITQUEUE(wait, current);
1059 set_current_state(TASK_UNINTERRUPTIBLE);
1060 add_wait_queue(&audit_backlog_wait, &wait);
1062 if (audit_backlog_limit &&
1063 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1064 schedule_timeout(sleep_time);
1066 __set_current_state(TASK_RUNNING);
1067 remove_wait_queue(&audit_backlog_wait, &wait);
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_session_info(struct audit_buffer *ab)
1381 u32 sessionid = audit_get_sessionid(current);
1382 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1384 audit_log_format(ab, " auid=%u ses=%u", auid, sessionid);
1387 void audit_log_key(struct audit_buffer *ab, char *key)
1389 audit_log_format(ab, " key=");
1391 audit_log_untrustedstring(ab, key);
1393 audit_log_format(ab, "(null)");
1396 void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1400 audit_log_format(ab, " %s=", prefix);
1401 CAP_FOR_EACH_U32(i) {
1402 audit_log_format(ab, "%08x",
1403 cap->cap[(_KERNEL_CAPABILITY_U32S-1) - i]);
1407 void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1409 kernel_cap_t *perm = &name->fcap.permitted;
1410 kernel_cap_t *inh = &name->fcap.inheritable;
1413 if (!cap_isclear(*perm)) {
1414 audit_log_cap(ab, "cap_fp", perm);
1417 if (!cap_isclear(*inh)) {
1418 audit_log_cap(ab, "cap_fi", inh);
1423 audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1424 name->fcap.fE, name->fcap_ver);
1427 static inline int audit_copy_fcaps(struct audit_names *name,
1428 const struct dentry *dentry)
1430 struct cpu_vfs_cap_data caps;
1436 rc = get_vfs_caps_from_disk(dentry, &caps);
1440 name->fcap.permitted = caps.permitted;
1441 name->fcap.inheritable = caps.inheritable;
1442 name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1443 name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1444 VFS_CAP_REVISION_SHIFT;
1449 /* Copy inode data into an audit_names. */
1450 void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1451 const struct inode *inode)
1453 name->ino = inode->i_ino;
1454 name->dev = inode->i_sb->s_dev;
1455 name->mode = inode->i_mode;
1456 name->uid = inode->i_uid;
1457 name->gid = inode->i_gid;
1458 name->rdev = inode->i_rdev;
1459 security_inode_getsecid(inode, &name->osid);
1460 audit_copy_fcaps(name, dentry);
1464 * audit_log_name - produce AUDIT_PATH record from struct audit_names
1465 * @context: audit_context for the task
1466 * @n: audit_names structure with reportable details
1467 * @path: optional path to report instead of audit_names->name
1468 * @record_num: record number to report when handling a list of names
1469 * @call_panic: optional pointer to int that will be updated if secid fails
1471 void audit_log_name(struct audit_context *context, struct audit_names *n,
1472 struct path *path, int record_num, int *call_panic)
1474 struct audit_buffer *ab;
1475 ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1479 audit_log_format(ab, "item=%d", record_num);
1482 audit_log_d_path(ab, " name=", path);
1484 switch (n->name_len) {
1485 case AUDIT_NAME_FULL:
1486 /* log the full path */
1487 audit_log_format(ab, " name=");
1488 audit_log_untrustedstring(ab, n->name->name);
1491 /* name was specified as a relative path and the
1492 * directory component is the cwd */
1493 audit_log_d_path(ab, " name=", &context->pwd);
1496 /* log the name's directory component */
1497 audit_log_format(ab, " name=");
1498 audit_log_n_untrustedstring(ab, n->name->name,
1502 audit_log_format(ab, " name=(null)");
1504 if (n->ino != (unsigned long)-1) {
1505 audit_log_format(ab, " inode=%lu"
1506 " dev=%02x:%02x mode=%#ho"
1507 " ouid=%u ogid=%u rdev=%02x:%02x",
1512 from_kuid(&init_user_ns, n->uid),
1513 from_kgid(&init_user_ns, n->gid),
1520 if (security_secid_to_secctx(
1521 n->osid, &ctx, &len)) {
1522 audit_log_format(ab, " osid=%u", n->osid);
1526 audit_log_format(ab, " obj=%s", ctx);
1527 security_release_secctx(ctx, len);
1531 audit_log_fcaps(ab, n);
1535 int audit_log_task_context(struct audit_buffer *ab)
1542 security_task_getsecid(current, &sid);
1546 error = security_secid_to_secctx(sid, &ctx, &len);
1548 if (error != -EINVAL)
1553 audit_log_format(ab, " subj=%s", ctx);
1554 security_release_secctx(ctx, len);
1558 audit_panic("error in audit_log_task_context");
1561 EXPORT_SYMBOL(audit_log_task_context);
1563 void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
1565 const struct cred *cred;
1566 char name[sizeof(tsk->comm)];
1567 struct mm_struct *mm = tsk->mm;
1573 /* tsk == current */
1574 cred = current_cred();
1576 spin_lock_irq(&tsk->sighand->siglock);
1577 if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
1578 tty = tsk->signal->tty->name;
1581 spin_unlock_irq(&tsk->sighand->siglock);
1583 audit_log_format(ab,
1584 " ppid=%ld pid=%d auid=%u uid=%u gid=%u"
1585 " euid=%u suid=%u fsuid=%u"
1586 " egid=%u sgid=%u fsgid=%u ses=%u tty=%s",
1589 from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
1590 from_kuid(&init_user_ns, cred->uid),
1591 from_kgid(&init_user_ns, cred->gid),
1592 from_kuid(&init_user_ns, cred->euid),
1593 from_kuid(&init_user_ns, cred->suid),
1594 from_kuid(&init_user_ns, cred->fsuid),
1595 from_kgid(&init_user_ns, cred->egid),
1596 from_kgid(&init_user_ns, cred->sgid),
1597 from_kgid(&init_user_ns, cred->fsgid),
1598 audit_get_sessionid(tsk), tty);
1600 get_task_comm(name, tsk);
1601 audit_log_format(ab, " comm=");
1602 audit_log_untrustedstring(ab, name);
1605 down_read(&mm->mmap_sem);
1607 audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
1608 up_read(&mm->mmap_sem);
1610 audit_log_task_context(ab);
1612 EXPORT_SYMBOL(audit_log_task_info);
1615 * audit_log_link_denied - report a link restriction denial
1616 * @operation: specific link opreation
1617 * @link: the path that triggered the restriction
1619 void audit_log_link_denied(const char *operation, struct path *link)
1621 struct audit_buffer *ab;
1622 struct audit_names *name;
1624 name = kzalloc(sizeof(*name), GFP_NOFS);
1628 /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
1629 ab = audit_log_start(current->audit_context, GFP_KERNEL,
1633 audit_log_format(ab, "op=%s", operation);
1634 audit_log_task_info(ab, current);
1635 audit_log_format(ab, " res=0");
1638 /* Generate AUDIT_PATH record with object. */
1639 name->type = AUDIT_TYPE_NORMAL;
1640 audit_copy_inode(name, link->dentry, link->dentry->d_inode);
1641 audit_log_name(current->audit_context, name, link, 0, NULL);
1647 * audit_log_end - end one audit record
1648 * @ab: the audit_buffer
1650 * The netlink_* functions cannot be called inside an irq context, so
1651 * the audit buffer is placed on a queue and a tasklet is scheduled to
1652 * remove them from the queue outside the irq context. May be called in
1655 void audit_log_end(struct audit_buffer *ab)
1659 if (!audit_rate_check()) {
1660 audit_log_lost("rate limit exceeded");
1662 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1663 nlh->nlmsg_len = ab->skb->len - NLMSG_HDRLEN;
1666 skb_queue_tail(&audit_skb_queue, ab->skb);
1667 wake_up_interruptible(&kauditd_wait);
1669 audit_printk_skb(ab->skb);
1673 audit_buffer_free(ab);
1677 * audit_log - Log an audit record
1678 * @ctx: audit context
1679 * @gfp_mask: type of allocation
1680 * @type: audit message type
1681 * @fmt: format string to use
1682 * @...: variable parameters matching the format string
1684 * This is a convenience function that calls audit_log_start,
1685 * audit_log_vformat, and audit_log_end. It may be called
1688 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1689 const char *fmt, ...)
1691 struct audit_buffer *ab;
1694 ab = audit_log_start(ctx, gfp_mask, type);
1696 va_start(args, fmt);
1697 audit_log_vformat(ab, fmt, args);
1703 #ifdef CONFIG_SECURITY
1705 * audit_log_secctx - Converts and logs SELinux context
1707 * @secid: security number
1709 * This is a helper function that calls security_secid_to_secctx to convert
1710 * secid to secctx and then adds the (converted) SELinux context to the audit
1711 * log by calling audit_log_format, thus also preventing leak of internal secid
1712 * to userspace. If secid cannot be converted audit_panic is called.
1714 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1719 if (security_secid_to_secctx(secid, &secctx, &len)) {
1720 audit_panic("Cannot convert secid to context");
1722 audit_log_format(ab, " obj=%s", secctx);
1723 security_release_secctx(secctx, len);
1726 EXPORT_SYMBOL(audit_log_secctx);
1729 EXPORT_SYMBOL(audit_log_start);
1730 EXPORT_SYMBOL(audit_log_end);
1731 EXPORT_SYMBOL(audit_log_format);
1732 EXPORT_SYMBOL(audit_log);