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 2003-2004 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 SELinux.
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 <asm/atomic.h>
48 #include <linux/module.h>
49 #include <linux/err.h>
50 #include <linux/kthread.h>
52 #include <linux/audit.h>
55 #include <net/netlink.h>
56 #include <linux/skbuff.h>
57 #include <linux/netlink.h>
58 #include <linux/selinux.h>
62 /* No auditing will take place until audit_initialized != 0.
63 * (Initialization happens after skb_init is called.) */
64 static int audit_initialized
;
66 /* No syscall auditing will take place unless audit_enabled != 0. */
69 /* Default state when kernel boots without any parameters. */
70 static int audit_default
;
72 /* If auditing cannot proceed, audit_failure selects what happens. */
73 static int audit_failure
= AUDIT_FAIL_PRINTK
;
75 /* If audit records are to be written to the netlink socket, audit_pid
76 * contains the (non-zero) pid. */
79 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
80 * to that number per second. This prevents DoS attacks, but results in
81 * audit records being dropped. */
82 static int audit_rate_limit
;
84 /* Number of outstanding audit_buffers allowed. */
85 static int audit_backlog_limit
= 64;
86 static int audit_backlog_wait_time
= 60 * HZ
;
87 static int audit_backlog_wait_overflow
= 0;
89 /* The identity of the user shutting down the audit system. */
90 uid_t audit_sig_uid
= -1;
91 pid_t audit_sig_pid
= -1;
93 /* Records can be lost in several ways:
94 0) [suppressed in audit_alloc]
95 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
96 2) out of memory in audit_log_move [alloc_skb]
97 3) suppressed due to audit_rate_limit
98 4) suppressed due to audit_backlog_limit
100 static atomic_t audit_lost
= ATOMIC_INIT(0);
102 /* The netlink socket. */
103 static struct sock
*audit_sock
;
105 /* The audit_freelist is a list of pre-allocated audit buffers (if more
106 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
107 * being placed on the freelist). */
108 static DEFINE_SPINLOCK(audit_freelist_lock
);
109 static int audit_freelist_count
;
110 static LIST_HEAD(audit_freelist
);
112 static struct sk_buff_head audit_skb_queue
;
113 static struct task_struct
*kauditd_task
;
114 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait
);
115 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait
);
117 /* The netlink socket is only to be read by 1 CPU, which lets us assume
118 * that list additions and deletions never happen simultaneously in
120 DEFINE_MUTEX(audit_netlink_mutex
);
122 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
123 * audit records. Since printk uses a 1024 byte buffer, this buffer
124 * should be at least that large. */
125 #define AUDIT_BUFSIZ 1024
127 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
128 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
129 #define AUDIT_MAXFREE (2*NR_CPUS)
131 /* The audit_buffer is used when formatting an audit record. The caller
132 * locks briefly to get the record off the freelist or to allocate the
133 * buffer, and locks briefly to send the buffer to the netlink layer or
134 * to place it on a transmit queue. Multiple audit_buffers can be in
135 * use simultaneously. */
136 struct audit_buffer
{
137 struct list_head list
;
138 struct sk_buff
*skb
; /* formatted skb ready to send */
139 struct audit_context
*ctx
; /* NULL or associated context */
143 static void audit_set_pid(struct audit_buffer
*ab
, pid_t pid
)
145 struct nlmsghdr
*nlh
= (struct nlmsghdr
*)ab
->skb
->data
;
146 nlh
->nlmsg_pid
= pid
;
149 void audit_panic(const char *message
)
151 switch (audit_failure
)
153 case AUDIT_FAIL_SILENT
:
155 case AUDIT_FAIL_PRINTK
:
156 printk(KERN_ERR
"audit: %s\n", message
);
158 case AUDIT_FAIL_PANIC
:
159 panic("audit: %s\n", message
);
164 static inline int audit_rate_check(void)
166 static unsigned long last_check
= 0;
167 static int messages
= 0;
168 static DEFINE_SPINLOCK(lock
);
171 unsigned long elapsed
;
174 if (!audit_rate_limit
) return 1;
176 spin_lock_irqsave(&lock
, flags
);
177 if (++messages
< audit_rate_limit
) {
181 elapsed
= now
- last_check
;
188 spin_unlock_irqrestore(&lock
, flags
);
194 * audit_log_lost - conditionally log lost audit message event
195 * @message: the message stating reason for lost audit message
197 * Emit at least 1 message per second, even if audit_rate_check is
199 * Always increment the lost messages counter.
201 void audit_log_lost(const char *message
)
203 static unsigned long last_msg
= 0;
204 static DEFINE_SPINLOCK(lock
);
209 atomic_inc(&audit_lost
);
211 print
= (audit_failure
== AUDIT_FAIL_PANIC
|| !audit_rate_limit
);
214 spin_lock_irqsave(&lock
, flags
);
216 if (now
- last_msg
> HZ
) {
220 spin_unlock_irqrestore(&lock
, flags
);
225 "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n",
226 atomic_read(&audit_lost
),
228 audit_backlog_limit
);
229 audit_panic(message
);
233 static int audit_set_rate_limit(int limit
, uid_t loginuid
)
235 int old
= audit_rate_limit
;
236 audit_rate_limit
= limit
;
237 audit_log(NULL
, GFP_KERNEL
, AUDIT_CONFIG_CHANGE
,
238 "audit_rate_limit=%d old=%d by auid=%u",
239 audit_rate_limit
, old
, loginuid
);
243 static int audit_set_backlog_limit(int limit
, uid_t loginuid
)
245 int old
= audit_backlog_limit
;
246 audit_backlog_limit
= limit
;
247 audit_log(NULL
, GFP_KERNEL
, AUDIT_CONFIG_CHANGE
,
248 "audit_backlog_limit=%d old=%d by auid=%u",
249 audit_backlog_limit
, old
, loginuid
);
253 static int audit_set_enabled(int state
, uid_t loginuid
)
255 int old
= audit_enabled
;
256 if (state
!= 0 && state
!= 1)
258 audit_enabled
= state
;
259 audit_log(NULL
, GFP_KERNEL
, AUDIT_CONFIG_CHANGE
,
260 "audit_enabled=%d old=%d by auid=%u",
261 audit_enabled
, old
, loginuid
);
265 static int audit_set_failure(int state
, uid_t loginuid
)
267 int old
= audit_failure
;
268 if (state
!= AUDIT_FAIL_SILENT
269 && state
!= AUDIT_FAIL_PRINTK
270 && state
!= AUDIT_FAIL_PANIC
)
272 audit_failure
= state
;
273 audit_log(NULL
, GFP_KERNEL
, AUDIT_CONFIG_CHANGE
,
274 "audit_failure=%d old=%d by auid=%u",
275 audit_failure
, old
, loginuid
);
279 static int kauditd_thread(void *dummy
)
284 skb
= skb_dequeue(&audit_skb_queue
);
285 wake_up(&audit_backlog_wait
);
288 int err
= netlink_unicast(audit_sock
, skb
, audit_pid
, 0);
290 BUG_ON(err
!= -ECONNREFUSED
); /* Shoudn't happen */
291 printk(KERN_ERR
"audit: *NO* daemon at audit_pid=%d\n", audit_pid
);
295 printk(KERN_NOTICE
"%s\n", skb
->data
+ NLMSG_SPACE(0));
299 DECLARE_WAITQUEUE(wait
, current
);
300 set_current_state(TASK_INTERRUPTIBLE
);
301 add_wait_queue(&kauditd_wait
, &wait
);
303 if (!skb_queue_len(&audit_skb_queue
)) {
308 __set_current_state(TASK_RUNNING
);
309 remove_wait_queue(&kauditd_wait
, &wait
);
316 * audit_send_reply - send an audit reply message via netlink
317 * @pid: process id to send reply to
318 * @seq: sequence number
319 * @type: audit message type
320 * @done: done (last) flag
321 * @multi: multi-part message flag
322 * @payload: payload data
323 * @size: payload size
325 * Allocates an skb, builds the netlink message, and sends it to the pid.
326 * No failure notifications.
328 void audit_send_reply(int pid
, int seq
, int type
, int done
, int multi
,
329 void *payload
, int size
)
332 struct nlmsghdr
*nlh
;
333 int len
= NLMSG_SPACE(size
);
335 int flags
= multi
? NLM_F_MULTI
: 0;
336 int t
= done
? NLMSG_DONE
: type
;
338 skb
= alloc_skb(len
, GFP_KERNEL
);
342 nlh
= NLMSG_PUT(skb
, pid
, seq
, t
, size
);
343 nlh
->nlmsg_flags
= flags
;
344 data
= NLMSG_DATA(nlh
);
345 memcpy(data
, payload
, size
);
347 /* Ignore failure. It'll only happen if the sender goes away,
348 because our timeout is set to infinite. */
349 netlink_unicast(audit_sock
, skb
, pid
, 0);
352 nlmsg_failure
: /* Used by NLMSG_PUT */
358 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
361 static int audit_netlink_ok(kernel_cap_t eff_cap
, u16 msg_type
)
368 case AUDIT_LIST_RULES
:
374 case AUDIT_SIGNAL_INFO
:
375 if (!cap_raised(eff_cap
, CAP_AUDIT_CONTROL
))
379 case AUDIT_FIRST_USER_MSG
...AUDIT_LAST_USER_MSG
:
380 case AUDIT_FIRST_USER_MSG2
...AUDIT_LAST_USER_MSG2
:
381 if (!cap_raised(eff_cap
, CAP_AUDIT_WRITE
))
384 default: /* bad msg */
391 static int audit_receive_msg(struct sk_buff
*skb
, struct nlmsghdr
*nlh
)
393 u32 uid
, pid
, seq
, sid
;
395 struct audit_status
*status_get
, status_set
;
397 struct audit_buffer
*ab
;
398 u16 msg_type
= nlh
->nlmsg_type
;
399 uid_t loginuid
; /* loginuid of sender */
400 struct audit_sig_info sig_data
;
402 err
= audit_netlink_ok(NETLINK_CB(skb
).eff_cap
, msg_type
);
406 /* As soon as there's any sign of userspace auditd,
407 * start kauditd to talk to it */
409 kauditd_task
= kthread_run(kauditd_thread
, NULL
, "kauditd");
410 if (IS_ERR(kauditd_task
)) {
411 err
= PTR_ERR(kauditd_task
);
416 pid
= NETLINK_CREDS(skb
)->pid
;
417 uid
= NETLINK_CREDS(skb
)->uid
;
418 loginuid
= NETLINK_CB(skb
).loginuid
;
419 sid
= NETLINK_CB(skb
).sid
;
420 seq
= nlh
->nlmsg_seq
;
421 data
= NLMSG_DATA(nlh
);
425 status_set
.enabled
= audit_enabled
;
426 status_set
.failure
= audit_failure
;
427 status_set
.pid
= audit_pid
;
428 status_set
.rate_limit
= audit_rate_limit
;
429 status_set
.backlog_limit
= audit_backlog_limit
;
430 status_set
.lost
= atomic_read(&audit_lost
);
431 status_set
.backlog
= skb_queue_len(&audit_skb_queue
);
432 audit_send_reply(NETLINK_CB(skb
).pid
, seq
, AUDIT_GET
, 0, 0,
433 &status_set
, sizeof(status_set
));
436 if (nlh
->nlmsg_len
< sizeof(struct audit_status
))
438 status_get
= (struct audit_status
*)data
;
439 if (status_get
->mask
& AUDIT_STATUS_ENABLED
) {
440 err
= audit_set_enabled(status_get
->enabled
, loginuid
);
441 if (err
< 0) return err
;
443 if (status_get
->mask
& AUDIT_STATUS_FAILURE
) {
444 err
= audit_set_failure(status_get
->failure
, loginuid
);
445 if (err
< 0) return err
;
447 if (status_get
->mask
& AUDIT_STATUS_PID
) {
449 audit_pid
= status_get
->pid
;
450 audit_log(NULL
, GFP_KERNEL
, AUDIT_CONFIG_CHANGE
,
451 "audit_pid=%d old=%d by auid=%u",
452 audit_pid
, old
, loginuid
);
454 if (status_get
->mask
& AUDIT_STATUS_RATE_LIMIT
)
455 audit_set_rate_limit(status_get
->rate_limit
, loginuid
);
456 if (status_get
->mask
& AUDIT_STATUS_BACKLOG_LIMIT
)
457 audit_set_backlog_limit(status_get
->backlog_limit
,
461 case AUDIT_FIRST_USER_MSG
...AUDIT_LAST_USER_MSG
:
462 case AUDIT_FIRST_USER_MSG2
...AUDIT_LAST_USER_MSG2
:
463 if (!audit_enabled
&& msg_type
!= AUDIT_USER_AVC
)
466 err
= audit_filter_user(&NETLINK_CB(skb
), msg_type
);
469 ab
= audit_log_start(NULL
, GFP_KERNEL
, msg_type
);
472 "user pid=%d uid=%u auid=%u",
477 if (selinux_ctxid_to_string(
481 /* Maybe call audit_panic? */
487 audit_log_format(ab
, " msg='%.1024s'",
489 audit_set_pid(ab
, pid
);
496 if (nlmsg_len(nlh
) < sizeof(struct audit_rule
))
500 err
= audit_receive_filter(nlh
->nlmsg_type
, NETLINK_CB(skb
).pid
,
501 uid
, seq
, data
, nlmsg_len(nlh
),
506 if (nlmsg_len(nlh
) < sizeof(struct audit_rule_data
))
509 case AUDIT_LIST_RULES
:
510 err
= audit_receive_filter(nlh
->nlmsg_type
, NETLINK_CB(skb
).pid
,
511 uid
, seq
, data
, nlmsg_len(nlh
),
514 case AUDIT_SIGNAL_INFO
:
515 sig_data
.uid
= audit_sig_uid
;
516 sig_data
.pid
= audit_sig_pid
;
517 audit_send_reply(NETLINK_CB(skb
).pid
, seq
, AUDIT_SIGNAL_INFO
,
518 0, 0, &sig_data
, sizeof(sig_data
));
525 return err
< 0 ? err
: 0;
529 * Get message from skb (based on rtnetlink_rcv_skb). Each message is
530 * processed by audit_receive_msg. Malformed skbs with wrong length are
531 * discarded silently.
533 static void audit_receive_skb(struct sk_buff
*skb
)
536 struct nlmsghdr
*nlh
;
539 while (skb
->len
>= NLMSG_SPACE(0)) {
540 nlh
= (struct nlmsghdr
*)skb
->data
;
541 if (nlh
->nlmsg_len
< sizeof(*nlh
) || skb
->len
< nlh
->nlmsg_len
)
543 rlen
= NLMSG_ALIGN(nlh
->nlmsg_len
);
546 if ((err
= audit_receive_msg(skb
, nlh
))) {
547 netlink_ack(skb
, nlh
, err
);
548 } else if (nlh
->nlmsg_flags
& NLM_F_ACK
)
549 netlink_ack(skb
, nlh
, 0);
554 /* Receive messages from netlink socket. */
555 static void audit_receive(struct sock
*sk
, int length
)
560 mutex_lock(&audit_netlink_mutex
);
562 for (qlen
= skb_queue_len(&sk
->sk_receive_queue
); qlen
; qlen
--) {
563 skb
= skb_dequeue(&sk
->sk_receive_queue
);
564 audit_receive_skb(skb
);
567 mutex_unlock(&audit_netlink_mutex
);
571 /* Initialize audit support at boot time. */
572 static int __init
audit_init(void)
574 printk(KERN_INFO
"audit: initializing netlink socket (%s)\n",
575 audit_default
? "enabled" : "disabled");
576 audit_sock
= netlink_kernel_create(NETLINK_AUDIT
, 0, audit_receive
,
579 audit_panic("cannot initialize netlink socket");
581 audit_sock
->sk_sndtimeo
= MAX_SCHEDULE_TIMEOUT
;
583 skb_queue_head_init(&audit_skb_queue
);
584 audit_initialized
= 1;
585 audit_enabled
= audit_default
;
587 /* Register the callback with selinux. This callback will be invoked
588 * when a new policy is loaded. */
589 selinux_audit_set_callback(&selinux_audit_rule_update
);
591 audit_log(NULL
, GFP_KERNEL
, AUDIT_KERNEL
, "initialized");
594 __initcall(audit_init
);
596 /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
597 static int __init
audit_enable(char *str
)
599 audit_default
= !!simple_strtol(str
, NULL
, 0);
600 printk(KERN_INFO
"audit: %s%s\n",
601 audit_default
? "enabled" : "disabled",
602 audit_initialized
? "" : " (after initialization)");
603 if (audit_initialized
)
604 audit_enabled
= audit_default
;
608 __setup("audit=", audit_enable
);
610 static void audit_buffer_free(struct audit_buffer
*ab
)
620 spin_lock_irqsave(&audit_freelist_lock
, flags
);
621 if (++audit_freelist_count
> AUDIT_MAXFREE
)
624 list_add(&ab
->list
, &audit_freelist
);
625 spin_unlock_irqrestore(&audit_freelist_lock
, flags
);
628 static struct audit_buffer
* audit_buffer_alloc(struct audit_context
*ctx
,
629 gfp_t gfp_mask
, int type
)
632 struct audit_buffer
*ab
= NULL
;
633 struct nlmsghdr
*nlh
;
635 spin_lock_irqsave(&audit_freelist_lock
, flags
);
636 if (!list_empty(&audit_freelist
)) {
637 ab
= list_entry(audit_freelist
.next
,
638 struct audit_buffer
, list
);
640 --audit_freelist_count
;
642 spin_unlock_irqrestore(&audit_freelist_lock
, flags
);
645 ab
= kmalloc(sizeof(*ab
), gfp_mask
);
650 ab
->skb
= alloc_skb(AUDIT_BUFSIZ
, gfp_mask
);
655 ab
->gfp_mask
= gfp_mask
;
656 nlh
= (struct nlmsghdr
*)skb_put(ab
->skb
, NLMSG_SPACE(0));
657 nlh
->nlmsg_type
= type
;
658 nlh
->nlmsg_flags
= 0;
663 audit_buffer_free(ab
);
668 * audit_serial - compute a serial number for the audit record
670 * Compute a serial number for the audit record. Audit records are
671 * written to user-space as soon as they are generated, so a complete
672 * audit record may be written in several pieces. The timestamp of the
673 * record and this serial number are used by the user-space tools to
674 * determine which pieces belong to the same audit record. The
675 * (timestamp,serial) tuple is unique for each syscall and is live from
676 * syscall entry to syscall exit.
678 * NOTE: Another possibility is to store the formatted records off the
679 * audit context (for those records that have a context), and emit them
680 * all at syscall exit. However, this could delay the reporting of
681 * significant errors until syscall exit (or never, if the system
684 unsigned int audit_serial(void)
686 static spinlock_t serial_lock
= SPIN_LOCK_UNLOCKED
;
687 static unsigned int serial
= 0;
692 spin_lock_irqsave(&serial_lock
, flags
);
695 } while (unlikely(!ret
));
696 spin_unlock_irqrestore(&serial_lock
, flags
);
701 static inline void audit_get_stamp(struct audit_context
*ctx
,
702 struct timespec
*t
, unsigned int *serial
)
705 auditsc_get_stamp(ctx
, t
, serial
);
708 *serial
= audit_serial();
712 /* Obtain an audit buffer. This routine does locking to obtain the
713 * audit buffer, but then no locking is required for calls to
714 * audit_log_*format. If the tsk is a task that is currently in a
715 * syscall, then the syscall is marked as auditable and an audit record
716 * will be written at syscall exit. If there is no associated task, tsk
720 * audit_log_start - obtain an audit buffer
721 * @ctx: audit_context (may be NULL)
722 * @gfp_mask: type of allocation
723 * @type: audit message type
725 * Returns audit_buffer pointer on success or NULL on error.
727 * Obtain an audit buffer. This routine does locking to obtain the
728 * audit buffer, but then no locking is required for calls to
729 * audit_log_*format. If the task (ctx) is a task that is currently in a
730 * syscall, then the syscall is marked as auditable and an audit record
731 * will be written at syscall exit. If there is no associated task, then
732 * task context (ctx) should be NULL.
734 struct audit_buffer
*audit_log_start(struct audit_context
*ctx
, gfp_t gfp_mask
,
737 struct audit_buffer
*ab
= NULL
;
741 unsigned long timeout_start
= jiffies
;
743 if (!audit_initialized
)
746 if (unlikely(audit_filter_type(type
)))
749 if (gfp_mask
& __GFP_WAIT
)
752 reserve
= 5; /* Allow atomic callers to go up to five
753 entries over the normal backlog limit */
755 while (audit_backlog_limit
756 && skb_queue_len(&audit_skb_queue
) > audit_backlog_limit
+ reserve
) {
757 if (gfp_mask
& __GFP_WAIT
&& audit_backlog_wait_time
758 && time_before(jiffies
, timeout_start
+ audit_backlog_wait_time
)) {
760 /* Wait for auditd to drain the queue a little */
761 DECLARE_WAITQUEUE(wait
, current
);
762 set_current_state(TASK_INTERRUPTIBLE
);
763 add_wait_queue(&audit_backlog_wait
, &wait
);
765 if (audit_backlog_limit
&&
766 skb_queue_len(&audit_skb_queue
) > audit_backlog_limit
)
767 schedule_timeout(timeout_start
+ audit_backlog_wait_time
- jiffies
);
769 __set_current_state(TASK_RUNNING
);
770 remove_wait_queue(&audit_backlog_wait
, &wait
);
773 if (audit_rate_check())
775 "audit: audit_backlog=%d > "
776 "audit_backlog_limit=%d\n",
777 skb_queue_len(&audit_skb_queue
),
778 audit_backlog_limit
);
779 audit_log_lost("backlog limit exceeded");
780 audit_backlog_wait_time
= audit_backlog_wait_overflow
;
781 wake_up(&audit_backlog_wait
);
785 ab
= audit_buffer_alloc(ctx
, gfp_mask
, type
);
787 audit_log_lost("out of memory in audit_log_start");
791 audit_get_stamp(ab
->ctx
, &t
, &serial
);
793 audit_log_format(ab
, "audit(%lu.%03lu:%u): ",
794 t
.tv_sec
, t
.tv_nsec
/1000000, serial
);
799 * audit_expand - expand skb in the audit buffer
801 * @extra: space to add at tail of the skb
803 * Returns 0 (no space) on failed expansion, or available space if
806 static inline int audit_expand(struct audit_buffer
*ab
, int extra
)
808 struct sk_buff
*skb
= ab
->skb
;
809 int ret
= pskb_expand_head(skb
, skb_headroom(skb
), extra
,
812 audit_log_lost("out of memory in audit_expand");
815 return skb_tailroom(skb
);
819 * Format an audit message into the audit buffer. If there isn't enough
820 * room in the audit buffer, more room will be allocated and vsnprint
821 * will be called a second time. Currently, we assume that a printk
822 * can't format message larger than 1024 bytes, so we don't either.
824 static void audit_log_vformat(struct audit_buffer
*ab
, const char *fmt
,
836 avail
= skb_tailroom(skb
);
838 avail
= audit_expand(ab
, AUDIT_BUFSIZ
);
842 va_copy(args2
, args
);
843 len
= vsnprintf(skb
->tail
, avail
, fmt
, args
);
845 /* The printk buffer is 1024 bytes long, so if we get
846 * here and AUDIT_BUFSIZ is at least 1024, then we can
847 * log everything that printk could have logged. */
848 avail
= audit_expand(ab
,
849 max_t(unsigned, AUDIT_BUFSIZ
, 1+len
-avail
));
852 len
= vsnprintf(skb
->tail
, avail
, fmt
, args2
);
861 * audit_log_format - format a message into the audit buffer.
863 * @fmt: format string
864 * @...: optional parameters matching @fmt string
866 * All the work is done in audit_log_vformat.
868 void audit_log_format(struct audit_buffer
*ab
, const char *fmt
, ...)
875 audit_log_vformat(ab
, fmt
, args
);
880 * audit_log_hex - convert a buffer to hex and append it to the audit skb
881 * @ab: the audit_buffer
882 * @buf: buffer to convert to hex
883 * @len: length of @buf to be converted
885 * No return value; failure to expand is silently ignored.
887 * This function will take the passed buf and convert it into a string of
888 * ascii hex digits. The new string is placed onto the skb.
890 void audit_log_hex(struct audit_buffer
*ab
, const unsigned char *buf
,
893 int i
, avail
, new_len
;
896 static const unsigned char *hex
= "0123456789ABCDEF";
900 avail
= skb_tailroom(skb
);
902 if (new_len
>= avail
) {
903 /* Round the buffer request up to the next multiple */
904 new_len
= AUDIT_BUFSIZ
*(((new_len
-avail
)/AUDIT_BUFSIZ
) + 1);
905 avail
= audit_expand(ab
, new_len
);
911 for (i
=0; i
<len
; i
++) {
912 *ptr
++ = hex
[(buf
[i
] & 0xF0)>>4]; /* Upper nibble */
913 *ptr
++ = hex
[buf
[i
] & 0x0F]; /* Lower nibble */
916 skb_put(skb
, len
<< 1); /* new string is twice the old string */
920 * audit_log_unstrustedstring - log a string that may contain random characters
922 * @string: string to be logged
924 * This code will escape a string that is passed to it if the string
925 * contains a control character, unprintable character, double quote mark,
926 * or a space. Unescaped strings will start and end with a double quote mark.
927 * Strings that are escaped are printed in hex (2 digits per char).
929 void audit_log_untrustedstring(struct audit_buffer
*ab
, const char *string
)
931 const unsigned char *p
= string
;
934 if (*p
== '"' || *p
< 0x21 || *p
> 0x7f) {
935 audit_log_hex(ab
, string
, strlen(string
));
940 audit_log_format(ab
, "\"%s\"", string
);
943 /* This is a helper-function to print the escaped d_path */
944 void audit_log_d_path(struct audit_buffer
*ab
, const char *prefix
,
945 struct dentry
*dentry
, struct vfsmount
*vfsmnt
)
950 audit_log_format(ab
, " %s", prefix
);
952 /* We will allow 11 spaces for ' (deleted)' to be appended */
953 path
= kmalloc(PATH_MAX
+11, ab
->gfp_mask
);
955 audit_log_format(ab
, "<no memory>");
958 p
= d_path(dentry
, vfsmnt
, path
, PATH_MAX
+11);
959 if (IS_ERR(p
)) { /* Should never happen since we send PATH_MAX */
960 /* FIXME: can we save some information here? */
961 audit_log_format(ab
, "<too long>");
963 audit_log_untrustedstring(ab
, p
);
968 * audit_log_end - end one audit record
969 * @ab: the audit_buffer
971 * The netlink_* functions cannot be called inside an irq context, so
972 * the audit buffer is placed on a queue and a tasklet is scheduled to
973 * remove them from the queue outside the irq context. May be called in
976 void audit_log_end(struct audit_buffer
*ab
)
980 if (!audit_rate_check()) {
981 audit_log_lost("rate limit exceeded");
984 struct nlmsghdr
*nlh
= (struct nlmsghdr
*)ab
->skb
->data
;
985 nlh
->nlmsg_len
= ab
->skb
->len
- NLMSG_SPACE(0);
986 skb_queue_tail(&audit_skb_queue
, ab
->skb
);
988 wake_up_interruptible(&kauditd_wait
);
990 printk(KERN_NOTICE
"%s\n", ab
->skb
->data
+ NLMSG_SPACE(0));
993 audit_buffer_free(ab
);
997 * audit_log - Log an audit record
998 * @ctx: audit context
999 * @gfp_mask: type of allocation
1000 * @type: audit message type
1001 * @fmt: format string to use
1002 * @...: variable parameters matching the format string
1004 * This is a convenience function that calls audit_log_start,
1005 * audit_log_vformat, and audit_log_end. It may be called
1008 void audit_log(struct audit_context
*ctx
, gfp_t gfp_mask
, int type
,
1009 const char *fmt
, ...)
1011 struct audit_buffer
*ab
;
1014 ab
= audit_log_start(ctx
, gfp_mask
, type
);
1016 va_start(args
, fmt
);
1017 audit_log_vformat(ab
, fmt
, args
);
1023 EXPORT_SYMBOL(audit_log_start
);
1024 EXPORT_SYMBOL(audit_log_end
);
1025 EXPORT_SYMBOL(audit_log_format
);
1026 EXPORT_SYMBOL(audit_log
);