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,
268 kuid_t loginuid, u32 sessionid, u32 sid,
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 auid=%u ses=%u", function_name, new,
278 old, from_kuid(&init_user_ns, loginuid), sessionid);
283 rc = security_secid_to_secctx(sid, &ctx, &len);
285 audit_log_format(ab, " sid=%u", sid);
286 allow_changes = 0; /* Something weird, deny request */
288 audit_log_format(ab, " subj=%s", ctx);
289 security_release_secctx(ctx, len);
292 audit_log_format(ab, " res=%d", allow_changes);
297 static int audit_do_config_change(char *function_name, int *to_change,
298 int new, kuid_t loginuid, u32 sessionid,
301 int allow_changes, rc = 0, old = *to_change;
303 /* check if we are locked */
304 if (audit_enabled == AUDIT_LOCKED)
309 if (audit_enabled != AUDIT_OFF) {
310 rc = audit_log_config_change(function_name, new, old, loginuid,
311 sessionid, sid, allow_changes);
316 /* If we are allowed, make the change */
317 if (allow_changes == 1)
319 /* Not allowed, update reason */
325 static int audit_set_rate_limit(int limit, kuid_t loginuid, u32 sessionid,
328 return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
329 limit, loginuid, sessionid, sid);
332 static int audit_set_backlog_limit(int limit, kuid_t loginuid, u32 sessionid,
335 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
336 limit, loginuid, sessionid, sid);
339 static int audit_set_enabled(int state, kuid_t loginuid, u32 sessionid, u32 sid)
342 if (state < AUDIT_OFF || state > AUDIT_LOCKED)
345 rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
346 loginuid, sessionid, sid);
349 audit_ever_enabled |= !!state;
354 static int audit_set_failure(int state, kuid_t loginuid, u32 sessionid, u32 sid)
356 if (state != AUDIT_FAIL_SILENT
357 && state != AUDIT_FAIL_PRINTK
358 && state != AUDIT_FAIL_PANIC)
361 return audit_do_config_change("audit_failure", &audit_failure, state,
362 loginuid, sessionid, sid);
366 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
367 * already have been sent via prink/syslog and so if these messages are dropped
368 * it is not a huge concern since we already passed the audit_log_lost()
369 * notification and stuff. This is just nice to get audit messages during
370 * boot before auditd is running or messages generated while auditd is stopped.
371 * This only holds messages is audit_default is set, aka booting with audit=1
372 * or building your kernel that way.
374 static void audit_hold_skb(struct sk_buff *skb)
377 skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
378 skb_queue_tail(&audit_skb_hold_queue, skb);
384 * For one reason or another this nlh isn't getting delivered to the userspace
385 * audit daemon, just send it to printk.
387 static void audit_printk_skb(struct sk_buff *skb)
389 struct nlmsghdr *nlh = nlmsg_hdr(skb);
390 char *data = nlmsg_data(nlh);
392 if (nlh->nlmsg_type != AUDIT_EOE) {
393 if (printk_ratelimit())
394 printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
396 audit_log_lost("printk limit exceeded\n");
402 static void kauditd_send_skb(struct sk_buff *skb)
405 /* take a reference in case we can't send it and we want to hold it */
407 err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
409 BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
410 printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
411 audit_log_lost("auditd disappeared\n");
413 /* we might get lucky and get this in the next auditd */
416 /* drop the extra reference if sent ok */
421 * flush_hold_queue - empty the hold queue if auditd appears
423 * If auditd just started, drain the queue of messages already
424 * sent to syslog/printk. Remember loss here is ok. We already
425 * called audit_log_lost() if it didn't go out normally. so the
426 * race between the skb_dequeue and the next check for audit_pid
429 * If you ever find kauditd to be too slow we can get a perf win
430 * by doing our own locking and keeping better track if there
431 * are messages in this queue. I don't see the need now, but
432 * in 5 years when I want to play with this again I'll see this
433 * note and still have no friggin idea what i'm thinking today.
435 static void flush_hold_queue(void)
439 if (!audit_default || !audit_pid)
442 skb = skb_dequeue(&audit_skb_hold_queue);
446 while (skb && audit_pid) {
447 kauditd_send_skb(skb);
448 skb = skb_dequeue(&audit_skb_hold_queue);
452 * if auditd just disappeared but we
453 * dequeued an skb we need to drop ref
459 static int kauditd_thread(void *dummy)
462 while (!kthread_should_stop()) {
464 DECLARE_WAITQUEUE(wait, current);
468 skb = skb_dequeue(&audit_skb_queue);
469 wake_up(&audit_backlog_wait);
472 kauditd_send_skb(skb);
474 audit_printk_skb(skb);
477 set_current_state(TASK_INTERRUPTIBLE);
478 add_wait_queue(&kauditd_wait, &wait);
480 if (!skb_queue_len(&audit_skb_queue)) {
485 __set_current_state(TASK_RUNNING);
486 remove_wait_queue(&kauditd_wait, &wait);
491 int audit_send_list(void *_dest)
493 struct audit_netlink_list *dest = _dest;
497 /* wait for parent to finish and send an ACK */
498 mutex_lock(&audit_cmd_mutex);
499 mutex_unlock(&audit_cmd_mutex);
501 while ((skb = __skb_dequeue(&dest->q)) != NULL)
502 netlink_unicast(audit_sock, skb, pid, 0);
509 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
510 int multi, const void *payload, int size)
513 struct nlmsghdr *nlh;
515 int flags = multi ? NLM_F_MULTI : 0;
516 int t = done ? NLMSG_DONE : type;
518 skb = nlmsg_new(size, GFP_KERNEL);
522 nlh = nlmsg_put(skb, pid, seq, t, size, flags);
525 data = nlmsg_data(nlh);
526 memcpy(data, payload, size);
534 static int audit_send_reply_thread(void *arg)
536 struct audit_reply *reply = (struct audit_reply *)arg;
538 mutex_lock(&audit_cmd_mutex);
539 mutex_unlock(&audit_cmd_mutex);
541 /* Ignore failure. It'll only happen if the sender goes away,
542 because our timeout is set to infinite. */
543 netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
548 * audit_send_reply - send an audit reply message via netlink
549 * @pid: process id to send reply to
550 * @seq: sequence number
551 * @type: audit message type
552 * @done: done (last) flag
553 * @multi: multi-part message flag
554 * @payload: payload data
555 * @size: payload size
557 * Allocates an skb, builds the netlink message, and sends it to the pid.
558 * No failure notifications.
560 static void audit_send_reply(int pid, int seq, int type, int done, int multi,
561 const void *payload, int size)
564 struct task_struct *tsk;
565 struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
571 skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
578 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
587 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
590 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
594 /* Only support the initial namespaces for now. */
595 if ((current_user_ns() != &init_user_ns) ||
596 (task_active_pid_ns(current) != &init_pid_ns))
602 case AUDIT_LIST_RULES:
608 case AUDIT_SIGNAL_INFO:
612 case AUDIT_MAKE_EQUIV:
613 if (!capable(CAP_AUDIT_CONTROL))
617 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
618 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
619 if (!capable(CAP_AUDIT_WRITE))
622 default: /* bad msg */
629 static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
630 kuid_t auid, u32 ses, u32 sid)
636 if (!audit_enabled) {
641 *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
644 audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
645 task_tgid_vnr(current),
646 from_kuid(&init_user_ns, current_uid()),
647 from_kuid(&init_user_ns, auid), ses);
649 rc = security_secid_to_secctx(sid, &ctx, &len);
651 audit_log_format(*ab, " ssid=%u", sid);
653 audit_log_format(*ab, " subj=%s", ctx);
654 security_release_secctx(ctx, len);
661 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
665 struct audit_status *status_get, status_set;
667 struct audit_buffer *ab;
668 u16 msg_type = nlh->nlmsg_type;
669 kuid_t loginuid; /* loginuid of sender */
671 struct audit_sig_info *sig_data;
675 err = audit_netlink_ok(skb, msg_type);
679 /* As soon as there's any sign of userspace auditd,
680 * start kauditd to talk to it */
682 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
683 if (IS_ERR(kauditd_task)) {
684 err = PTR_ERR(kauditd_task);
689 loginuid = audit_get_loginuid(current);
690 sessionid = audit_get_sessionid(current);
691 security_task_getsecid(current, &sid);
692 seq = nlh->nlmsg_seq;
693 data = nlmsg_data(nlh);
697 status_set.enabled = audit_enabled;
698 status_set.failure = audit_failure;
699 status_set.pid = audit_pid;
700 status_set.rate_limit = audit_rate_limit;
701 status_set.backlog_limit = audit_backlog_limit;
702 status_set.lost = atomic_read(&audit_lost);
703 status_set.backlog = skb_queue_len(&audit_skb_queue);
704 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
705 &status_set, sizeof(status_set));
708 if (nlh->nlmsg_len < sizeof(struct audit_status))
710 status_get = (struct audit_status *)data;
711 if (status_get->mask & AUDIT_STATUS_ENABLED) {
712 err = audit_set_enabled(status_get->enabled,
713 loginuid, sessionid, sid);
717 if (status_get->mask & AUDIT_STATUS_FAILURE) {
718 err = audit_set_failure(status_get->failure,
719 loginuid, sessionid, sid);
723 if (status_get->mask & AUDIT_STATUS_PID) {
724 int new_pid = status_get->pid;
726 if (audit_enabled != AUDIT_OFF)
727 audit_log_config_change("audit_pid", new_pid,
732 audit_nlk_portid = NETLINK_CB(skb).portid;
734 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
735 err = audit_set_rate_limit(status_get->rate_limit,
736 loginuid, sessionid, sid);
740 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
741 err = audit_set_backlog_limit(status_get->backlog_limit,
742 loginuid, sessionid, sid);
745 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
746 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
747 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
750 err = audit_filter_user();
753 if (msg_type == AUDIT_USER_TTY) {
754 err = tty_audit_push_task(current, loginuid,
759 audit_log_common_recv_msg(&ab, msg_type,
760 loginuid, sessionid, sid);
762 if (msg_type != AUDIT_USER_TTY)
763 audit_log_format(ab, " msg='%.1024s'",
768 audit_log_format(ab, " msg=");
769 size = nlmsg_len(nlh);
771 ((unsigned char *)data)[size - 1] == '\0')
773 audit_log_n_untrustedstring(ab, data, size);
775 audit_set_pid(ab, NETLINK_CB(skb).portid);
781 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
783 if (audit_enabled == AUDIT_LOCKED) {
784 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
785 loginuid, sessionid, sid);
787 audit_log_format(ab, " audit_enabled=%d res=0",
794 err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
795 seq, data, nlmsg_len(nlh),
796 loginuid, sessionid, sid);
800 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
802 if (audit_enabled == AUDIT_LOCKED) {
803 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
804 loginuid, sessionid, sid);
806 audit_log_format(ab, " audit_enabled=%d res=0",
812 case AUDIT_LIST_RULES:
813 err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
814 seq, data, nlmsg_len(nlh),
815 loginuid, sessionid, sid);
820 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
821 loginuid, sessionid, sid);
823 audit_log_format(ab, " op=trim res=1");
826 case AUDIT_MAKE_EQUIV: {
829 size_t msglen = nlmsg_len(nlh);
833 if (msglen < 2 * sizeof(u32))
835 memcpy(sizes, bufp, 2 * sizeof(u32));
836 bufp += 2 * sizeof(u32);
837 msglen -= 2 * sizeof(u32);
838 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
843 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
849 /* OK, here comes... */
850 err = audit_tag_tree(old, new);
852 audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
853 loginuid, sessionid, sid);
855 audit_log_format(ab, " op=make_equiv old=");
856 audit_log_untrustedstring(ab, old);
857 audit_log_format(ab, " new=");
858 audit_log_untrustedstring(ab, new);
859 audit_log_format(ab, " res=%d", !err);
865 case AUDIT_SIGNAL_INFO:
868 err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
872 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
875 security_release_secctx(ctx, len);
878 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
879 sig_data->pid = audit_sig_pid;
881 memcpy(sig_data->ctx, ctx, len);
882 security_release_secctx(ctx, len);
884 audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO,
885 0, 0, sig_data, sizeof(*sig_data) + len);
888 case AUDIT_TTY_GET: {
889 struct audit_tty_status s;
890 struct task_struct *tsk = current;
892 spin_lock_irq(&tsk->sighand->siglock);
893 s.enabled = tsk->signal->audit_tty != 0;
894 spin_unlock_irq(&tsk->sighand->siglock);
896 audit_send_reply(NETLINK_CB(skb).portid, seq,
897 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
900 case AUDIT_TTY_SET: {
901 struct audit_tty_status *s;
902 struct task_struct *tsk = current;
904 if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
907 if (s->enabled != 0 && s->enabled != 1)
910 spin_lock_irq(&tsk->sighand->siglock);
911 tsk->signal->audit_tty = s->enabled != 0;
912 spin_unlock_irq(&tsk->sighand->siglock);
920 return err < 0 ? err : 0;
924 * Get message from skb. Each message is processed by audit_receive_msg.
925 * Malformed skbs with wrong length are discarded silently.
927 static void audit_receive_skb(struct sk_buff *skb)
929 struct nlmsghdr *nlh;
931 * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
932 * if the nlmsg_len was not aligned
937 nlh = nlmsg_hdr(skb);
940 while (NLMSG_OK(nlh, len)) {
941 err = audit_receive_msg(skb, nlh);
942 /* if err or if this message says it wants a response */
943 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
944 netlink_ack(skb, nlh, err);
946 nlh = NLMSG_NEXT(nlh, len);
950 /* Receive messages from netlink socket. */
951 static void audit_receive(struct sk_buff *skb)
953 mutex_lock(&audit_cmd_mutex);
954 audit_receive_skb(skb);
955 mutex_unlock(&audit_cmd_mutex);
958 /* Initialize audit support at boot time. */
959 static int __init audit_init(void)
962 struct netlink_kernel_cfg cfg = {
963 .input = audit_receive,
966 if (audit_initialized == AUDIT_DISABLED)
969 printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
970 audit_default ? "enabled" : "disabled");
971 audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
973 audit_panic("cannot initialize netlink socket");
975 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
977 skb_queue_head_init(&audit_skb_queue);
978 skb_queue_head_init(&audit_skb_hold_queue);
979 audit_initialized = AUDIT_INITIALIZED;
980 audit_enabled = audit_default;
981 audit_ever_enabled |= !!audit_default;
983 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
985 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
986 INIT_LIST_HEAD(&audit_inode_hash[i]);
990 __initcall(audit_init);
992 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
993 static int __init audit_enable(char *str)
995 audit_default = !!simple_strtol(str, NULL, 0);
997 audit_initialized = AUDIT_DISABLED;
999 printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
1001 if (audit_initialized == AUDIT_INITIALIZED) {
1002 audit_enabled = audit_default;
1003 audit_ever_enabled |= !!audit_default;
1004 } else if (audit_initialized == AUDIT_UNINITIALIZED) {
1005 printk(" (after initialization)");
1007 printk(" (until reboot)");
1014 __setup("audit=", audit_enable);
1016 static void audit_buffer_free(struct audit_buffer *ab)
1018 unsigned long flags;
1026 spin_lock_irqsave(&audit_freelist_lock, flags);
1027 if (audit_freelist_count > AUDIT_MAXFREE)
1030 audit_freelist_count++;
1031 list_add(&ab->list, &audit_freelist);
1033 spin_unlock_irqrestore(&audit_freelist_lock, flags);
1036 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1037 gfp_t gfp_mask, int type)
1039 unsigned long flags;
1040 struct audit_buffer *ab = NULL;
1041 struct nlmsghdr *nlh;
1043 spin_lock_irqsave(&audit_freelist_lock, flags);
1044 if (!list_empty(&audit_freelist)) {
1045 ab = list_entry(audit_freelist.next,
1046 struct audit_buffer, list);
1047 list_del(&ab->list);
1048 --audit_freelist_count;
1050 spin_unlock_irqrestore(&audit_freelist_lock, flags);
1053 ab = kmalloc(sizeof(*ab), gfp_mask);
1059 ab->gfp_mask = gfp_mask;
1061 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1065 nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1075 audit_buffer_free(ab);
1080 * audit_serial - compute a serial number for the audit record
1082 * Compute a serial number for the audit record. Audit records are
1083 * written to user-space as soon as they are generated, so a complete
1084 * audit record may be written in several pieces. The timestamp of the
1085 * record and this serial number are used by the user-space tools to
1086 * determine which pieces belong to the same audit record. The
1087 * (timestamp,serial) tuple is unique for each syscall and is live from
1088 * syscall entry to syscall exit.
1090 * NOTE: Another possibility is to store the formatted records off the
1091 * audit context (for those records that have a context), and emit them
1092 * all at syscall exit. However, this could delay the reporting of
1093 * significant errors until syscall exit (or never, if the system
1096 unsigned int audit_serial(void)
1098 static DEFINE_SPINLOCK(serial_lock);
1099 static unsigned int serial = 0;
1101 unsigned long flags;
1104 spin_lock_irqsave(&serial_lock, flags);
1107 } while (unlikely(!ret));
1108 spin_unlock_irqrestore(&serial_lock, flags);
1113 static inline void audit_get_stamp(struct audit_context *ctx,
1114 struct timespec *t, unsigned int *serial)
1116 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1118 *serial = audit_serial();
1123 * Wait for auditd to drain the queue a little
1125 static void wait_for_auditd(unsigned long sleep_time)
1127 DECLARE_WAITQUEUE(wait, current);
1128 set_current_state(TASK_INTERRUPTIBLE);
1129 add_wait_queue(&audit_backlog_wait, &wait);
1131 if (audit_backlog_limit &&
1132 skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1133 schedule_timeout(sleep_time);
1135 __set_current_state(TASK_RUNNING);
1136 remove_wait_queue(&audit_backlog_wait, &wait);
1139 /* Obtain an audit buffer. This routine does locking to obtain the
1140 * audit buffer, but then no locking is required for calls to
1141 * audit_log_*format. If the tsk is a task that is currently in a
1142 * syscall, then the syscall is marked as auditable and an audit record
1143 * will be written at syscall exit. If there is no associated task, tsk
1144 * should be NULL. */
1147 * audit_log_start - obtain an audit buffer
1148 * @ctx: audit_context (may be NULL)
1149 * @gfp_mask: type of allocation
1150 * @type: audit message type
1152 * Returns audit_buffer pointer on success or NULL on error.
1154 * Obtain an audit buffer. This routine does locking to obtain the
1155 * audit buffer, but then no locking is required for calls to
1156 * audit_log_*format. If the task (ctx) is a task that is currently in a
1157 * syscall, then the syscall is marked as auditable and an audit record
1158 * will be written at syscall exit. If there is no associated task, then
1159 * task context (ctx) should be NULL.
1161 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1164 struct audit_buffer *ab = NULL;
1166 unsigned int uninitialized_var(serial);
1168 unsigned long timeout_start = jiffies;
1170 if (audit_initialized != AUDIT_INITIALIZED)
1173 if (unlikely(audit_filter_type(type)))
1176 if (gfp_mask & __GFP_WAIT)
1179 reserve = 5; /* Allow atomic callers to go up to five
1180 entries over the normal backlog limit */
1182 while (audit_backlog_limit
1183 && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1184 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
1185 unsigned long sleep_time;
1187 sleep_time = timeout_start + audit_backlog_wait_time -
1189 if ((long)sleep_time > 0)
1190 wait_for_auditd(sleep_time);
1193 if (audit_rate_check() && printk_ratelimit())
1195 "audit: audit_backlog=%d > "
1196 "audit_backlog_limit=%d\n",
1197 skb_queue_len(&audit_skb_queue),
1198 audit_backlog_limit);
1199 audit_log_lost("backlog limit exceeded");
1200 audit_backlog_wait_time = audit_backlog_wait_overflow;
1201 wake_up(&audit_backlog_wait);
1205 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1207 audit_log_lost("out of memory in audit_log_start");
1211 audit_get_stamp(ab->ctx, &t, &serial);
1213 audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1214 t.tv_sec, t.tv_nsec/1000000, serial);
1219 * audit_expand - expand skb in the audit buffer
1221 * @extra: space to add at tail of the skb
1223 * Returns 0 (no space) on failed expansion, or available space if
1226 static inline int audit_expand(struct audit_buffer *ab, int extra)
1228 struct sk_buff *skb = ab->skb;
1229 int oldtail = skb_tailroom(skb);
1230 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1231 int newtail = skb_tailroom(skb);
1234 audit_log_lost("out of memory in audit_expand");
1238 skb->truesize += newtail - oldtail;
1243 * Format an audit message into the audit buffer. If there isn't enough
1244 * room in the audit buffer, more room will be allocated and vsnprint
1245 * will be called a second time. Currently, we assume that a printk
1246 * can't format message larger than 1024 bytes, so we don't either.
1248 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1252 struct sk_buff *skb;
1260 avail = skb_tailroom(skb);
1262 avail = audit_expand(ab, AUDIT_BUFSIZ);
1266 va_copy(args2, args);
1267 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1269 /* The printk buffer is 1024 bytes long, so if we get
1270 * here and AUDIT_BUFSIZ is at least 1024, then we can
1271 * log everything that printk could have logged. */
1272 avail = audit_expand(ab,
1273 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1276 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1287 * audit_log_format - format a message into the audit buffer.
1289 * @fmt: format string
1290 * @...: optional parameters matching @fmt string
1292 * All the work is done in audit_log_vformat.
1294 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1300 va_start(args, fmt);
1301 audit_log_vformat(ab, fmt, args);
1306 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1307 * @ab: the audit_buffer
1308 * @buf: buffer to convert to hex
1309 * @len: length of @buf to be converted
1311 * No return value; failure to expand is silently ignored.
1313 * This function will take the passed buf and convert it into a string of
1314 * ascii hex digits. The new string is placed onto the skb.
1316 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1319 int i, avail, new_len;
1321 struct sk_buff *skb;
1322 static const unsigned char *hex = "0123456789ABCDEF";
1329 avail = skb_tailroom(skb);
1331 if (new_len >= avail) {
1332 /* Round the buffer request up to the next multiple */
1333 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1334 avail = audit_expand(ab, new_len);
1339 ptr = skb_tail_pointer(skb);
1340 for (i=0; i<len; i++) {
1341 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1342 *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1345 skb_put(skb, len << 1); /* new string is twice the old string */
1349 * Format a string of no more than slen characters into the audit buffer,
1350 * enclosed in quote marks.
1352 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1357 struct sk_buff *skb;
1364 avail = skb_tailroom(skb);
1365 new_len = slen + 3; /* enclosing quotes + null terminator */
1366 if (new_len > avail) {
1367 avail = audit_expand(ab, new_len);
1371 ptr = skb_tail_pointer(skb);
1373 memcpy(ptr, string, slen);
1377 skb_put(skb, slen + 2); /* don't include null terminator */
1381 * audit_string_contains_control - does a string need to be logged in hex
1382 * @string: string to be checked
1383 * @len: max length of the string to check
1385 int audit_string_contains_control(const char *string, size_t len)
1387 const unsigned char *p;
1388 for (p = string; p < (const unsigned char *)string + len; p++) {
1389 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1396 * audit_log_n_untrustedstring - log a string that may contain random characters
1398 * @len: length of string (not including trailing null)
1399 * @string: string to be logged
1401 * This code will escape a string that is passed to it if the string
1402 * contains a control character, unprintable character, double quote mark,
1403 * or a space. Unescaped strings will start and end with a double quote mark.
1404 * Strings that are escaped are printed in hex (2 digits per char).
1406 * The caller specifies the number of characters in the string to log, which may
1407 * or may not be the entire string.
1409 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1412 if (audit_string_contains_control(string, len))
1413 audit_log_n_hex(ab, string, len);
1415 audit_log_n_string(ab, string, len);
1419 * audit_log_untrustedstring - log a string that may contain random characters
1421 * @string: string to be logged
1423 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1424 * determine string length.
1426 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1428 audit_log_n_untrustedstring(ab, string, strlen(string));
1431 /* This is a helper-function to print the escaped d_path */
1432 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1433 const struct path *path)
1438 audit_log_format(ab, "%s", prefix);
1440 /* We will allow 11 spaces for ' (deleted)' to be appended */
1441 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1443 audit_log_string(ab, "<no_memory>");
1446 p = d_path(path, pathname, PATH_MAX+11);
1447 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1448 /* FIXME: can we save some information here? */
1449 audit_log_string(ab, "<too_long>");
1451 audit_log_untrustedstring(ab, p);
1455 void audit_log_key(struct audit_buffer *ab, char *key)
1457 audit_log_format(ab, " key=");
1459 audit_log_untrustedstring(ab, key);
1461 audit_log_format(ab, "(null)");
1465 * audit_log_link_denied - report a link restriction denial
1466 * @operation: specific link opreation
1467 * @link: the path that triggered the restriction
1469 void audit_log_link_denied(const char *operation, struct path *link)
1471 struct audit_buffer *ab;
1473 ab = audit_log_start(current->audit_context, GFP_KERNEL,
1477 audit_log_format(ab, "op=%s action=denied", operation);
1478 audit_log_format(ab, " pid=%d comm=", current->pid);
1479 audit_log_untrustedstring(ab, current->comm);
1480 audit_log_d_path(ab, " path=", link);
1481 audit_log_format(ab, " dev=");
1482 audit_log_untrustedstring(ab, link->dentry->d_inode->i_sb->s_id);
1483 audit_log_format(ab, " ino=%lu", link->dentry->d_inode->i_ino);
1488 * audit_log_end - end one audit record
1489 * @ab: the audit_buffer
1491 * The netlink_* functions cannot be called inside an irq context, so
1492 * the audit buffer is placed on a queue and a tasklet is scheduled to
1493 * remove them from the queue outside the irq context. May be called in
1496 void audit_log_end(struct audit_buffer *ab)
1500 if (!audit_rate_check()) {
1501 audit_log_lost("rate limit exceeded");
1503 struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1504 nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1507 skb_queue_tail(&audit_skb_queue, ab->skb);
1508 wake_up_interruptible(&kauditd_wait);
1510 audit_printk_skb(ab->skb);
1514 audit_buffer_free(ab);
1518 * audit_log - Log an audit record
1519 * @ctx: audit context
1520 * @gfp_mask: type of allocation
1521 * @type: audit message type
1522 * @fmt: format string to use
1523 * @...: variable parameters matching the format string
1525 * This is a convenience function that calls audit_log_start,
1526 * audit_log_vformat, and audit_log_end. It may be called
1529 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1530 const char *fmt, ...)
1532 struct audit_buffer *ab;
1535 ab = audit_log_start(ctx, gfp_mask, type);
1537 va_start(args, fmt);
1538 audit_log_vformat(ab, fmt, args);
1544 #ifdef CONFIG_SECURITY
1546 * audit_log_secctx - Converts and logs SELinux context
1548 * @secid: security number
1550 * This is a helper function that calls security_secid_to_secctx to convert
1551 * secid to secctx and then adds the (converted) SELinux context to the audit
1552 * log by calling audit_log_format, thus also preventing leak of internal secid
1553 * to userspace. If secid cannot be converted audit_panic is called.
1555 void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1560 if (security_secid_to_secctx(secid, &secctx, &len)) {
1561 audit_panic("Cannot convert secid to context");
1563 audit_log_format(ab, " obj=%s", secctx);
1564 security_release_secctx(secctx, len);
1567 EXPORT_SYMBOL(audit_log_secctx);
1570 EXPORT_SYMBOL(audit_log_start);
1571 EXPORT_SYMBOL(audit_log_end);
1572 EXPORT_SYMBOL(audit_log_format);
1573 EXPORT_SYMBOL(audit_log);