1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* audit.c -- Auditing support
3 * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
4 * System-call specific features have moved to auditsc.c
5 *
6 * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
7 * All Rights Reserved.
8 *
9 * Written by Rickard E. (Rik) Faith <faith@redhat.com>
10 *
11 * Goals: 1) Integrate fully with Security Modules.
12 * 2) Minimal run-time overhead:
13 * a) Minimal when syscall auditing is disabled (audit_enable=0).
14 * b) Small when syscall auditing is enabled and no audit record
15 * is generated (defer as much work as possible to record
16 * generation time):
17 * i) context is allocated,
18 * ii) names from getname are stored without a copy, and
19 * iii) inode information stored from path_lookup.
20 * 3) Ability to disable syscall auditing at boot time (audit=0).
21 * 4) Usable by other parts of the kernel (if audit_log* is called,
22 * then a syscall record will be generated automatically for the
23 * current syscall).
24 * 5) Netlink interface to user-space.
25 * 6) Support low-overhead kernel-based filtering to minimize the
26 * information that must be passed to user-space.
27 *
28 * Audit userspace, documentation, tests, and bug/issue trackers:
29 * https://github.com/linux-audit
30 */
31
32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
33
34 #include <linux/file.h>
35 #include <linux/init.h>
36 #include <linux/types.h>
37 #include <linux/atomic.h>
38 #include <linux/mm.h>
39 #include <linux/export.h>
40 #include <linux/slab.h>
41 #include <linux/err.h>
42 #include <linux/kthread.h>
43 #include <linux/kernel.h>
44 #include <linux/syscalls.h>
45 #include <linux/spinlock.h>
46 #include <linux/rcupdate.h>
47 #include <linux/mutex.h>
48 #include <linux/gfp.h>
49 #include <linux/pid.h>
50
51 #include <linux/audit.h>
52
53 #include <net/sock.h>
54 #include <net/netlink.h>
55 #include <linux/skbuff.h>
56 #include <linux/security.h>
57 #include <linux/freezer.h>
58 #include <linux/pid_namespace.h>
59 #include <net/netns/generic.h>
60
61 #include "audit.h"
62
63 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
64 * (Initialization happens after skb_init is called.) */
65 #define AUDIT_DISABLED -1
66 #define AUDIT_UNINITIALIZED 0
67 #define AUDIT_INITIALIZED 1
68 static int audit_initialized = AUDIT_UNINITIALIZED;
69
70 u32 audit_enabled = AUDIT_OFF;
71 bool audit_ever_enabled = !!AUDIT_OFF;
72
73 EXPORT_SYMBOL_GPL(audit_enabled);
74
75 /* Default state when kernel boots without any parameters. */
76 static u32 audit_default = AUDIT_OFF;
77
78 /* If auditing cannot proceed, audit_failure selects what happens. */
79 static u32 audit_failure = AUDIT_FAIL_PRINTK;
80
81 /* private audit network namespace index */
82 static unsigned int audit_net_id;
83
84 /**
85 * struct audit_net - audit private network namespace data
86 * @sk: communication socket
87 */
88 struct audit_net {
89 struct sock *sk;
90 };
91
92 /**
93 * struct auditd_connection - kernel/auditd connection state
94 * @pid: auditd PID
95 * @portid: netlink portid
96 * @net: the associated network namespace
97 * @rcu: RCU head
98 *
99 * Description:
100 * This struct is RCU protected; you must either hold the RCU lock for reading
101 * or the associated spinlock for writing.
102 */
103 struct auditd_connection {
104 struct pid *pid;
105 u32 portid;
106 struct net *net;
107 struct rcu_head rcu;
108 };
109 static struct auditd_connection __rcu *auditd_conn;
110 static DEFINE_SPINLOCK(auditd_conn_lock);
111
112 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
113 * to that number per second. This prevents DoS attacks, but results in
114 * audit records being dropped. */
115 static u32 audit_rate_limit;
116
117 /* Number of outstanding audit_buffers allowed.
118 * When set to zero, this means unlimited. */
119 static u32 audit_backlog_limit = 64;
120 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
121 static u32 audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
122
123 /* The identity of the user shutting down the audit system. */
124 static kuid_t audit_sig_uid = INVALID_UID;
125 static pid_t audit_sig_pid = -1;
126 static struct lsm_prop audit_sig_lsm;
127
128 /* Records can be lost in several ways:
129 0) [suppressed in audit_alloc]
130 1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
131 2) out of memory in audit_log_move [alloc_skb]
132 3) suppressed due to audit_rate_limit
133 4) suppressed due to audit_backlog_limit
134 */
135 static atomic_t audit_lost = ATOMIC_INIT(0);
136
137 /* Monotonically increasing sum of time the kernel has spent
138 * waiting while the backlog limit is exceeded.
139 */
140 static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
141
142 /* Hash for inode-based rules */
143 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
144
145 static struct kmem_cache *audit_buffer_cache;
146
147 /* queue msgs to send via kauditd_task */
148 static struct sk_buff_head audit_queue;
149 /* queue msgs due to temporary unicast send problems */
150 static struct sk_buff_head audit_retry_queue;
151 /* queue msgs waiting for new auditd connection */
152 static struct sk_buff_head audit_hold_queue;
153
154 /* queue servicing thread */
155 static struct task_struct *kauditd_task;
156 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
157
158 /* waitqueue for callers who are blocked on the audit backlog */
159 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
160
161 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
162 .mask = -1,
163 .features = 0,
164 .lock = 0,};
165
166 static char *audit_feature_names[2] = {
167 "only_unset_loginuid",
168 "loginuid_immutable",
169 };
170
171 /**
172 * struct audit_ctl_mutex - serialize requests from userspace
173 * @lock: the mutex used for locking
174 * @owner: the task which owns the lock
175 *
176 * Description:
177 * This is the lock struct used to ensure we only process userspace requests
178 * in an orderly fashion. We can't simply use a mutex/lock here because we
179 * need to track lock ownership so we don't end up blocking the lock owner in
180 * audit_log_start() or similar.
181 */
182 static struct audit_ctl_mutex {
183 struct mutex lock;
184 void *owner;
185 } audit_cmd_mutex;
186
187 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
188 * audit records. Since printk uses a 1024 byte buffer, this buffer
189 * should be at least that large. */
190 #define AUDIT_BUFSIZ 1024
191
192 /* The audit_buffer is used when formatting an audit record. The caller
193 * locks briefly to get the record off the freelist or to allocate the
194 * buffer, and locks briefly to send the buffer to the netlink layer or
195 * to place it on a transmit queue. Multiple audit_buffers can be in
196 * use simultaneously. */
197 struct audit_buffer {
198 struct sk_buff *skb; /* formatted skb ready to send */
199 struct audit_context *ctx; /* NULL or associated context */
200 gfp_t gfp_mask;
201 };
202
203 struct audit_reply {
204 __u32 portid;
205 struct net *net;
206 struct sk_buff *skb;
207 };
208
209 /**
210 * auditd_test_task - Check to see if a given task is an audit daemon
211 * @task: the task to check
212 *
213 * Description:
214 * Return 1 if the task is a registered audit daemon, 0 otherwise.
215 */
auditd_test_task(struct task_struct * task)216 int auditd_test_task(struct task_struct *task)
217 {
218 int rc;
219 struct auditd_connection *ac;
220
221 rcu_read_lock();
222 ac = rcu_dereference(auditd_conn);
223 rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
224 rcu_read_unlock();
225
226 return rc;
227 }
228
229 /**
230 * audit_ctl_lock - Take the audit control lock
231 */
audit_ctl_lock(void)232 void audit_ctl_lock(void)
233 {
234 mutex_lock(&audit_cmd_mutex.lock);
235 audit_cmd_mutex.owner = current;
236 }
237
238 /**
239 * audit_ctl_unlock - Drop the audit control lock
240 */
audit_ctl_unlock(void)241 void audit_ctl_unlock(void)
242 {
243 audit_cmd_mutex.owner = NULL;
244 mutex_unlock(&audit_cmd_mutex.lock);
245 }
246
247 /**
248 * audit_ctl_owner_current - Test to see if the current task owns the lock
249 *
250 * Description:
251 * Return true if the current task owns the audit control lock, false if it
252 * doesn't own the lock.
253 */
audit_ctl_owner_current(void)254 static bool audit_ctl_owner_current(void)
255 {
256 return (current == audit_cmd_mutex.owner);
257 }
258
259 /**
260 * auditd_pid_vnr - Return the auditd PID relative to the namespace
261 *
262 * Description:
263 * Returns the PID in relation to the namespace, 0 on failure.
264 */
auditd_pid_vnr(void)265 static pid_t auditd_pid_vnr(void)
266 {
267 pid_t pid;
268 const struct auditd_connection *ac;
269
270 rcu_read_lock();
271 ac = rcu_dereference(auditd_conn);
272 if (!ac || !ac->pid)
273 pid = 0;
274 else
275 pid = pid_vnr(ac->pid);
276 rcu_read_unlock();
277
278 return pid;
279 }
280
281 /**
282 * audit_get_sk - Return the audit socket for the given network namespace
283 * @net: the destination network namespace
284 *
285 * Description:
286 * Returns the sock pointer if valid, NULL otherwise. The caller must ensure
287 * that a reference is held for the network namespace while the sock is in use.
288 */
audit_get_sk(const struct net * net)289 static struct sock *audit_get_sk(const struct net *net)
290 {
291 struct audit_net *aunet;
292
293 if (!net)
294 return NULL;
295
296 aunet = net_generic(net, audit_net_id);
297 return aunet->sk;
298 }
299
audit_panic(const char * message)300 void audit_panic(const char *message)
301 {
302 switch (audit_failure) {
303 case AUDIT_FAIL_SILENT:
304 break;
305 case AUDIT_FAIL_PRINTK:
306 if (printk_ratelimit())
307 pr_err("%s\n", message);
308 break;
309 case AUDIT_FAIL_PANIC:
310 panic("audit: %s\n", message);
311 break;
312 }
313 }
314
audit_rate_check(void)315 static inline int audit_rate_check(void)
316 {
317 static unsigned long last_check = 0;
318 static int messages = 0;
319 static DEFINE_SPINLOCK(lock);
320 unsigned long flags;
321 unsigned long now;
322 int retval = 0;
323
324 if (!audit_rate_limit)
325 return 1;
326
327 spin_lock_irqsave(&lock, flags);
328 if (++messages < audit_rate_limit) {
329 retval = 1;
330 } else {
331 now = jiffies;
332 if (time_after(now, last_check + HZ)) {
333 last_check = now;
334 messages = 0;
335 retval = 1;
336 }
337 }
338 spin_unlock_irqrestore(&lock, flags);
339
340 return retval;
341 }
342
343 /**
344 * audit_log_lost - conditionally log lost audit message event
345 * @message: the message stating reason for lost audit message
346 *
347 * Emit at least 1 message per second, even if audit_rate_check is
348 * throttling.
349 * Always increment the lost messages counter.
350 */
audit_log_lost(const char * message)351 void audit_log_lost(const char *message)
352 {
353 static unsigned long last_msg = 0;
354 static DEFINE_SPINLOCK(lock);
355 unsigned long flags;
356 unsigned long now;
357 int print;
358
359 atomic_inc(&audit_lost);
360
361 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
362
363 if (!print) {
364 spin_lock_irqsave(&lock, flags);
365 now = jiffies;
366 if (time_after(now, last_msg + HZ)) {
367 print = 1;
368 last_msg = now;
369 }
370 spin_unlock_irqrestore(&lock, flags);
371 }
372
373 if (print) {
374 if (printk_ratelimit())
375 pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
376 atomic_read(&audit_lost),
377 audit_rate_limit,
378 audit_backlog_limit);
379 audit_panic(message);
380 }
381 }
382
audit_log_config_change(char * function_name,u32 new,u32 old,int allow_changes)383 static int audit_log_config_change(char *function_name, u32 new, u32 old,
384 int allow_changes)
385 {
386 struct audit_buffer *ab;
387 int rc = 0;
388
389 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
390 if (unlikely(!ab))
391 return rc;
392 audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
393 audit_log_session_info(ab);
394 rc = audit_log_task_context(ab);
395 if (rc)
396 allow_changes = 0; /* Something weird, deny request */
397 audit_log_format(ab, " res=%d", allow_changes);
398 audit_log_end(ab);
399 return rc;
400 }
401
audit_do_config_change(char * function_name,u32 * to_change,u32 new)402 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
403 {
404 int allow_changes, rc = 0;
405 u32 old = *to_change;
406
407 /* check if we are locked */
408 if (audit_enabled == AUDIT_LOCKED)
409 allow_changes = 0;
410 else
411 allow_changes = 1;
412
413 if (audit_enabled != AUDIT_OFF) {
414 rc = audit_log_config_change(function_name, new, old, allow_changes);
415 if (rc)
416 allow_changes = 0;
417 }
418
419 /* If we are allowed, make the change */
420 if (allow_changes == 1)
421 *to_change = new;
422 /* Not allowed, update reason */
423 else if (rc == 0)
424 rc = -EPERM;
425 return rc;
426 }
427
audit_set_rate_limit(u32 limit)428 static int audit_set_rate_limit(u32 limit)
429 {
430 return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
431 }
432
audit_set_backlog_limit(u32 limit)433 static int audit_set_backlog_limit(u32 limit)
434 {
435 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
436 }
437
audit_set_backlog_wait_time(u32 timeout)438 static int audit_set_backlog_wait_time(u32 timeout)
439 {
440 return audit_do_config_change("audit_backlog_wait_time",
441 &audit_backlog_wait_time, timeout);
442 }
443
audit_set_enabled(u32 state)444 static int audit_set_enabled(u32 state)
445 {
446 int rc;
447 if (state > AUDIT_LOCKED)
448 return -EINVAL;
449
450 rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
451 if (!rc)
452 audit_ever_enabled |= !!state;
453
454 return rc;
455 }
456
audit_set_failure(u32 state)457 static int audit_set_failure(u32 state)
458 {
459 if (state != AUDIT_FAIL_SILENT
460 && state != AUDIT_FAIL_PRINTK
461 && state != AUDIT_FAIL_PANIC)
462 return -EINVAL;
463
464 return audit_do_config_change("audit_failure", &audit_failure, state);
465 }
466
467 /**
468 * auditd_conn_free - RCU helper to release an auditd connection struct
469 * @rcu: RCU head
470 *
471 * Description:
472 * Drop any references inside the auditd connection tracking struct and free
473 * the memory.
474 */
auditd_conn_free(struct rcu_head * rcu)475 static void auditd_conn_free(struct rcu_head *rcu)
476 {
477 struct auditd_connection *ac;
478
479 ac = container_of(rcu, struct auditd_connection, rcu);
480 put_pid(ac->pid);
481 put_net(ac->net);
482 kfree(ac);
483 }
484
485 /**
486 * auditd_set - Set/Reset the auditd connection state
487 * @pid: auditd PID
488 * @portid: auditd netlink portid
489 * @net: auditd network namespace pointer
490 * @skb: the netlink command from the audit daemon
491 * @ack: netlink ack flag, cleared if ack'd here
492 *
493 * Description:
494 * This function will obtain and drop network namespace references as
495 * necessary. Returns zero on success, negative values on failure.
496 */
auditd_set(struct pid * pid,u32 portid,struct net * net,struct sk_buff * skb,bool * ack)497 static int auditd_set(struct pid *pid, u32 portid, struct net *net,
498 struct sk_buff *skb, bool *ack)
499 {
500 unsigned long flags;
501 struct auditd_connection *ac_old, *ac_new;
502 struct nlmsghdr *nlh;
503
504 if (!pid || !net)
505 return -EINVAL;
506
507 ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
508 if (!ac_new)
509 return -ENOMEM;
510 ac_new->pid = get_pid(pid);
511 ac_new->portid = portid;
512 ac_new->net = get_net(net);
513
514 /* send the ack now to avoid a race with the queue backlog */
515 if (*ack) {
516 nlh = nlmsg_hdr(skb);
517 netlink_ack(skb, nlh, 0, NULL);
518 *ack = false;
519 }
520
521 spin_lock_irqsave(&auditd_conn_lock, flags);
522 ac_old = rcu_dereference_protected(auditd_conn,
523 lockdep_is_held(&auditd_conn_lock));
524 rcu_assign_pointer(auditd_conn, ac_new);
525 spin_unlock_irqrestore(&auditd_conn_lock, flags);
526
527 if (ac_old)
528 call_rcu(&ac_old->rcu, auditd_conn_free);
529
530 return 0;
531 }
532
533 /**
534 * kauditd_printk_skb - Print the audit record to the ring buffer
535 * @skb: audit record
536 *
537 * Whatever the reason, this packet may not make it to the auditd connection
538 * so write it via printk so the information isn't completely lost.
539 */
kauditd_printk_skb(struct sk_buff * skb)540 static void kauditd_printk_skb(struct sk_buff *skb)
541 {
542 struct nlmsghdr *nlh = nlmsg_hdr(skb);
543 char *data = nlmsg_data(nlh);
544
545 if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
546 pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
547 }
548
549 /**
550 * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
551 * @skb: audit record
552 * @error: error code (unused)
553 *
554 * Description:
555 * This should only be used by the kauditd_thread when it fails to flush the
556 * hold queue.
557 */
kauditd_rehold_skb(struct sk_buff * skb,__always_unused int error)558 static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error)
559 {
560 /* put the record back in the queue */
561 skb_queue_tail(&audit_hold_queue, skb);
562 }
563
564 /**
565 * kauditd_hold_skb - Queue an audit record, waiting for auditd
566 * @skb: audit record
567 * @error: error code
568 *
569 * Description:
570 * Queue the audit record, waiting for an instance of auditd. When this
571 * function is called we haven't given up yet on sending the record, but things
572 * are not looking good. The first thing we want to do is try to write the
573 * record via printk and then see if we want to try and hold on to the record
574 * and queue it, if we have room. If we want to hold on to the record, but we
575 * don't have room, record a record lost message.
576 */
kauditd_hold_skb(struct sk_buff * skb,int error)577 static void kauditd_hold_skb(struct sk_buff *skb, int error)
578 {
579 /* at this point it is uncertain if we will ever send this to auditd so
580 * try to send the message via printk before we go any further */
581 kauditd_printk_skb(skb);
582
583 /* can we just silently drop the message? */
584 if (!audit_default)
585 goto drop;
586
587 /* the hold queue is only for when the daemon goes away completely,
588 * not -EAGAIN failures; if we are in a -EAGAIN state requeue the
589 * record on the retry queue unless it's full, in which case drop it
590 */
591 if (error == -EAGAIN) {
592 if (!audit_backlog_limit ||
593 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
594 skb_queue_tail(&audit_retry_queue, skb);
595 return;
596 }
597 audit_log_lost("kauditd retry queue overflow");
598 goto drop;
599 }
600
601 /* if we have room in the hold queue, queue the message */
602 if (!audit_backlog_limit ||
603 skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
604 skb_queue_tail(&audit_hold_queue, skb);
605 return;
606 }
607
608 /* we have no other options - drop the message */
609 audit_log_lost("kauditd hold queue overflow");
610 drop:
611 kfree_skb(skb);
612 }
613
614 /**
615 * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
616 * @skb: audit record
617 * @error: error code (unused)
618 *
619 * Description:
620 * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
621 * but for some reason we are having problems sending it audit records so
622 * queue the given record and attempt to resend.
623 */
kauditd_retry_skb(struct sk_buff * skb,__always_unused int error)624 static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
625 {
626 if (!audit_backlog_limit ||
627 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
628 skb_queue_tail(&audit_retry_queue, skb);
629 return;
630 }
631
632 /* we have to drop the record, send it via printk as a last effort */
633 kauditd_printk_skb(skb);
634 audit_log_lost("kauditd retry queue overflow");
635 kfree_skb(skb);
636 }
637
638 /**
639 * auditd_reset - Disconnect the auditd connection
640 * @ac: auditd connection state
641 *
642 * Description:
643 * Break the auditd/kauditd connection and move all the queued records into the
644 * hold queue in case auditd reconnects. It is important to note that the @ac
645 * pointer should never be dereferenced inside this function as it may be NULL
646 * or invalid, you can only compare the memory address! If @ac is NULL then
647 * the connection will always be reset.
648 */
auditd_reset(const struct auditd_connection * ac)649 static void auditd_reset(const struct auditd_connection *ac)
650 {
651 unsigned long flags;
652 struct sk_buff *skb;
653 struct auditd_connection *ac_old;
654
655 /* if it isn't already broken, break the connection */
656 spin_lock_irqsave(&auditd_conn_lock, flags);
657 ac_old = rcu_dereference_protected(auditd_conn,
658 lockdep_is_held(&auditd_conn_lock));
659 if (ac && ac != ac_old) {
660 /* someone already registered a new auditd connection */
661 spin_unlock_irqrestore(&auditd_conn_lock, flags);
662 return;
663 }
664 rcu_assign_pointer(auditd_conn, NULL);
665 spin_unlock_irqrestore(&auditd_conn_lock, flags);
666
667 if (ac_old)
668 call_rcu(&ac_old->rcu, auditd_conn_free);
669
670 /* flush the retry queue to the hold queue, but don't touch the main
671 * queue since we need to process that normally for multicast */
672 while ((skb = skb_dequeue(&audit_retry_queue)))
673 kauditd_hold_skb(skb, -ECONNREFUSED);
674 }
675
676 /**
677 * auditd_send_unicast_skb - Send a record via unicast to auditd
678 * @skb: audit record
679 *
680 * Description:
681 * Send a skb to the audit daemon, returns positive/zero values on success and
682 * negative values on failure; in all cases the skb will be consumed by this
683 * function. If the send results in -ECONNREFUSED the connection with auditd
684 * will be reset. This function may sleep so callers should not hold any locks
685 * where this would cause a problem.
686 */
auditd_send_unicast_skb(struct sk_buff * skb)687 static int auditd_send_unicast_skb(struct sk_buff *skb)
688 {
689 int rc;
690 u32 portid;
691 struct net *net;
692 struct sock *sk;
693 struct auditd_connection *ac;
694
695 /* NOTE: we can't call netlink_unicast while in the RCU section so
696 * take a reference to the network namespace and grab local
697 * copies of the namespace, the sock, and the portid; the
698 * namespace and sock aren't going to go away while we hold a
699 * reference and if the portid does become invalid after the RCU
700 * section netlink_unicast() should safely return an error */
701
702 rcu_read_lock();
703 ac = rcu_dereference(auditd_conn);
704 if (!ac) {
705 rcu_read_unlock();
706 kfree_skb(skb);
707 rc = -ECONNREFUSED;
708 goto err;
709 }
710 net = get_net(ac->net);
711 sk = audit_get_sk(net);
712 portid = ac->portid;
713 rcu_read_unlock();
714
715 rc = netlink_unicast(sk, skb, portid, 0);
716 put_net(net);
717 if (rc < 0)
718 goto err;
719
720 return rc;
721
722 err:
723 if (ac && rc == -ECONNREFUSED)
724 auditd_reset(ac);
725 return rc;
726 }
727
728 /**
729 * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
730 * @sk: the sending sock
731 * @portid: the netlink destination
732 * @queue: the skb queue to process
733 * @retry_limit: limit on number of netlink unicast failures
734 * @skb_hook: per-skb hook for additional processing
735 * @err_hook: hook called if the skb fails the netlink unicast send
736 *
737 * Description:
738 * Run through the given queue and attempt to send the audit records to auditd,
739 * returns zero on success, negative values on failure. It is up to the caller
740 * to ensure that the @sk is valid for the duration of this function.
741 *
742 */
kauditd_send_queue(struct sock * sk,u32 portid,struct sk_buff_head * queue,unsigned int retry_limit,void (* skb_hook)(struct sk_buff * skb),void (* err_hook)(struct sk_buff * skb,int error))743 static int kauditd_send_queue(struct sock *sk, u32 portid,
744 struct sk_buff_head *queue,
745 unsigned int retry_limit,
746 void (*skb_hook)(struct sk_buff *skb),
747 void (*err_hook)(struct sk_buff *skb, int error))
748 {
749 int rc = 0;
750 struct sk_buff *skb = NULL;
751 struct sk_buff *skb_tail;
752 unsigned int failed = 0;
753
754 /* NOTE: kauditd_thread takes care of all our locking, we just use
755 * the netlink info passed to us (e.g. sk and portid) */
756
757 skb_tail = skb_peek_tail(queue);
758 while ((skb != skb_tail) && (skb = skb_dequeue(queue))) {
759 /* call the skb_hook for each skb we touch */
760 if (skb_hook)
761 (*skb_hook)(skb);
762
763 /* can we send to anyone via unicast? */
764 if (!sk) {
765 if (err_hook)
766 (*err_hook)(skb, -ECONNREFUSED);
767 continue;
768 }
769
770 retry:
771 /* grab an extra skb reference in case of error */
772 skb_get(skb);
773 rc = netlink_unicast(sk, skb, portid, 0);
774 if (rc < 0) {
775 /* send failed - try a few times unless fatal error */
776 if (++failed >= retry_limit ||
777 rc == -ECONNREFUSED || rc == -EPERM) {
778 sk = NULL;
779 if (err_hook)
780 (*err_hook)(skb, rc);
781 if (rc == -EAGAIN)
782 rc = 0;
783 /* continue to drain the queue */
784 continue;
785 } else
786 goto retry;
787 } else {
788 /* skb sent - drop the extra reference and continue */
789 consume_skb(skb);
790 failed = 0;
791 }
792 }
793
794 return (rc >= 0 ? 0 : rc);
795 }
796
797 /*
798 * kauditd_send_multicast_skb - Send a record to any multicast listeners
799 * @skb: audit record
800 *
801 * Description:
802 * Write a multicast message to anyone listening in the initial network
803 * namespace. This function doesn't consume an skb as might be expected since
804 * it has to copy it anyways.
805 */
kauditd_send_multicast_skb(struct sk_buff * skb)806 static void kauditd_send_multicast_skb(struct sk_buff *skb)
807 {
808 struct sk_buff *copy;
809 struct sock *sock = audit_get_sk(&init_net);
810 struct nlmsghdr *nlh;
811
812 /* NOTE: we are not taking an additional reference for init_net since
813 * we don't have to worry about it going away */
814
815 if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
816 return;
817
818 /*
819 * The seemingly wasteful skb_copy() rather than bumping the refcount
820 * using skb_get() is necessary because non-standard mods are made to
821 * the skb by the original kaudit unicast socket send routine. The
822 * existing auditd daemon assumes this breakage. Fixing this would
823 * require co-ordinating a change in the established protocol between
824 * the kaudit kernel subsystem and the auditd userspace code. There is
825 * no reason for new multicast clients to continue with this
826 * non-compliance.
827 */
828 copy = skb_copy(skb, GFP_KERNEL);
829 if (!copy)
830 return;
831 nlh = nlmsg_hdr(copy);
832 nlh->nlmsg_len = skb->len;
833
834 nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
835 }
836
837 /**
838 * kauditd_thread - Worker thread to send audit records to userspace
839 * @dummy: unused
840 */
kauditd_thread(void * dummy)841 static int kauditd_thread(void *dummy)
842 {
843 int rc;
844 u32 portid = 0;
845 struct net *net = NULL;
846 struct sock *sk = NULL;
847 struct auditd_connection *ac;
848
849 #define UNICAST_RETRIES 5
850
851 set_freezable();
852 while (!kthread_should_stop()) {
853 /* NOTE: see the lock comments in auditd_send_unicast_skb() */
854 rcu_read_lock();
855 ac = rcu_dereference(auditd_conn);
856 if (!ac) {
857 rcu_read_unlock();
858 goto main_queue;
859 }
860 net = get_net(ac->net);
861 sk = audit_get_sk(net);
862 portid = ac->portid;
863 rcu_read_unlock();
864
865 /* attempt to flush the hold queue */
866 rc = kauditd_send_queue(sk, portid,
867 &audit_hold_queue, UNICAST_RETRIES,
868 NULL, kauditd_rehold_skb);
869 if (rc < 0) {
870 sk = NULL;
871 auditd_reset(ac);
872 goto main_queue;
873 }
874
875 /* attempt to flush the retry queue */
876 rc = kauditd_send_queue(sk, portid,
877 &audit_retry_queue, UNICAST_RETRIES,
878 NULL, kauditd_hold_skb);
879 if (rc < 0) {
880 sk = NULL;
881 auditd_reset(ac);
882 goto main_queue;
883 }
884
885 main_queue:
886 /* process the main queue - do the multicast send and attempt
887 * unicast, dump failed record sends to the retry queue; if
888 * sk == NULL due to previous failures we will just do the
889 * multicast send and move the record to the hold queue */
890 rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
891 kauditd_send_multicast_skb,
892 (sk ?
893 kauditd_retry_skb : kauditd_hold_skb));
894 if (ac && rc < 0)
895 auditd_reset(ac);
896 sk = NULL;
897
898 /* drop our netns reference, no auditd sends past this line */
899 if (net) {
900 put_net(net);
901 net = NULL;
902 }
903
904 /* we have processed all the queues so wake everyone */
905 wake_up(&audit_backlog_wait);
906
907 /* NOTE: we want to wake up if there is anything on the queue,
908 * regardless of if an auditd is connected, as we need to
909 * do the multicast send and rotate records from the
910 * main queue to the retry/hold queues */
911 wait_event_freezable(kauditd_wait,
912 (skb_queue_len(&audit_queue) ? 1 : 0));
913 }
914
915 return 0;
916 }
917
audit_send_list_thread(void * _dest)918 int audit_send_list_thread(void *_dest)
919 {
920 struct audit_netlink_list *dest = _dest;
921 struct sk_buff *skb;
922 struct sock *sk = audit_get_sk(dest->net);
923
924 /* wait for parent to finish and send an ACK */
925 audit_ctl_lock();
926 audit_ctl_unlock();
927
928 while ((skb = __skb_dequeue(&dest->q)) != NULL)
929 netlink_unicast(sk, skb, dest->portid, 0);
930
931 put_net(dest->net);
932 kfree(dest);
933
934 return 0;
935 }
936
audit_make_reply(int seq,int type,int done,int multi,const void * payload,int size)937 struct sk_buff *audit_make_reply(int seq, int type, int done,
938 int multi, const void *payload, int size)
939 {
940 struct sk_buff *skb;
941 struct nlmsghdr *nlh;
942 void *data;
943 int flags = multi ? NLM_F_MULTI : 0;
944 int t = done ? NLMSG_DONE : type;
945
946 skb = nlmsg_new(size, GFP_KERNEL);
947 if (!skb)
948 return NULL;
949
950 nlh = nlmsg_put(skb, 0, seq, t, size, flags);
951 if (!nlh)
952 goto out_kfree_skb;
953 data = nlmsg_data(nlh);
954 memcpy(data, payload, size);
955 return skb;
956
957 out_kfree_skb:
958 kfree_skb(skb);
959 return NULL;
960 }
961
audit_free_reply(struct audit_reply * reply)962 static void audit_free_reply(struct audit_reply *reply)
963 {
964 if (!reply)
965 return;
966
967 kfree_skb(reply->skb);
968 if (reply->net)
969 put_net(reply->net);
970 kfree(reply);
971 }
972
audit_send_reply_thread(void * arg)973 static int audit_send_reply_thread(void *arg)
974 {
975 struct audit_reply *reply = (struct audit_reply *)arg;
976
977 audit_ctl_lock();
978 audit_ctl_unlock();
979
980 /* Ignore failure. It'll only happen if the sender goes away,
981 because our timeout is set to infinite. */
982 netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
983 reply->skb = NULL;
984 audit_free_reply(reply);
985 return 0;
986 }
987
988 /**
989 * audit_send_reply - send an audit reply message via netlink
990 * @request_skb: skb of request we are replying to (used to target the reply)
991 * @seq: sequence number
992 * @type: audit message type
993 * @done: done (last) flag
994 * @multi: multi-part message flag
995 * @payload: payload data
996 * @size: payload size
997 *
998 * Allocates a skb, builds the netlink message, and sends it to the port id.
999 */
audit_send_reply(struct sk_buff * request_skb,int seq,int type,int done,int multi,const void * payload,int size)1000 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
1001 int multi, const void *payload, int size)
1002 {
1003 struct task_struct *tsk;
1004 struct audit_reply *reply;
1005
1006 reply = kzalloc(sizeof(*reply), GFP_KERNEL);
1007 if (!reply)
1008 return;
1009
1010 reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
1011 if (!reply->skb)
1012 goto err;
1013 reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
1014 reply->portid = NETLINK_CB(request_skb).portid;
1015
1016 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
1017 if (IS_ERR(tsk))
1018 goto err;
1019
1020 return;
1021
1022 err:
1023 audit_free_reply(reply);
1024 }
1025
1026 /*
1027 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
1028 * control messages.
1029 */
audit_netlink_ok(struct sk_buff * skb,u16 msg_type)1030 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1031 {
1032 int err = 0;
1033
1034 /* Only support initial user namespace for now. */
1035 /*
1036 * We return ECONNREFUSED because it tricks userspace into thinking
1037 * that audit was not configured into the kernel. Lots of users
1038 * configure their PAM stack (because that's what the distro does)
1039 * to reject login if unable to send messages to audit. If we return
1040 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1041 * configured in and will let login proceed. If we return EPERM
1042 * userspace will reject all logins. This should be removed when we
1043 * support non init namespaces!!
1044 */
1045 if (current_user_ns() != &init_user_ns)
1046 return -ECONNREFUSED;
1047
1048 switch (msg_type) {
1049 case AUDIT_LIST:
1050 case AUDIT_ADD:
1051 case AUDIT_DEL:
1052 return -EOPNOTSUPP;
1053 case AUDIT_GET:
1054 case AUDIT_SET:
1055 case AUDIT_GET_FEATURE:
1056 case AUDIT_SET_FEATURE:
1057 case AUDIT_LIST_RULES:
1058 case AUDIT_ADD_RULE:
1059 case AUDIT_DEL_RULE:
1060 case AUDIT_SIGNAL_INFO:
1061 case AUDIT_TTY_GET:
1062 case AUDIT_TTY_SET:
1063 case AUDIT_TRIM:
1064 case AUDIT_MAKE_EQUIV:
1065 /* Only support auditd and auditctl in initial pid namespace
1066 * for now. */
1067 if (task_active_pid_ns(current) != &init_pid_ns)
1068 return -EPERM;
1069
1070 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1071 err = -EPERM;
1072 break;
1073 case AUDIT_USER:
1074 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1075 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1076 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1077 err = -EPERM;
1078 break;
1079 default: /* bad msg */
1080 err = -EINVAL;
1081 }
1082
1083 return err;
1084 }
1085
audit_log_common_recv_msg(struct audit_context * context,struct audit_buffer ** ab,u16 msg_type)1086 static void audit_log_common_recv_msg(struct audit_context *context,
1087 struct audit_buffer **ab, u16 msg_type)
1088 {
1089 uid_t uid = from_kuid(&init_user_ns, current_uid());
1090 pid_t pid = task_tgid_nr(current);
1091
1092 if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1093 *ab = NULL;
1094 return;
1095 }
1096
1097 *ab = audit_log_start(context, GFP_KERNEL, msg_type);
1098 if (unlikely(!*ab))
1099 return;
1100 audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1101 audit_log_session_info(*ab);
1102 audit_log_task_context(*ab);
1103 }
1104
audit_log_user_recv_msg(struct audit_buffer ** ab,u16 msg_type)1105 static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1106 u16 msg_type)
1107 {
1108 audit_log_common_recv_msg(NULL, ab, msg_type);
1109 }
1110
is_audit_feature_set(int i)1111 static int is_audit_feature_set(int i)
1112 {
1113 return af.features & AUDIT_FEATURE_TO_MASK(i);
1114 }
1115
1116
audit_get_feature(struct sk_buff * skb)1117 static int audit_get_feature(struct sk_buff *skb)
1118 {
1119 u32 seq;
1120
1121 seq = nlmsg_hdr(skb)->nlmsg_seq;
1122
1123 audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1124
1125 return 0;
1126 }
1127
audit_log_feature_change(int which,u32 old_feature,u32 new_feature,u32 old_lock,u32 new_lock,int res)1128 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1129 u32 old_lock, u32 new_lock, int res)
1130 {
1131 struct audit_buffer *ab;
1132
1133 if (audit_enabled == AUDIT_OFF)
1134 return;
1135
1136 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1137 if (!ab)
1138 return;
1139 audit_log_task_info(ab);
1140 audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1141 audit_feature_names[which], !!old_feature, !!new_feature,
1142 !!old_lock, !!new_lock, res);
1143 audit_log_end(ab);
1144 }
1145
audit_set_feature(struct audit_features * uaf)1146 static int audit_set_feature(struct audit_features *uaf)
1147 {
1148 int i;
1149
1150 BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1151
1152 /* if there is ever a version 2 we should handle that here */
1153
1154 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1155 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1156 u32 old_feature, new_feature, old_lock, new_lock;
1157
1158 /* if we are not changing this feature, move along */
1159 if (!(feature & uaf->mask))
1160 continue;
1161
1162 old_feature = af.features & feature;
1163 new_feature = uaf->features & feature;
1164 new_lock = (uaf->lock | af.lock) & feature;
1165 old_lock = af.lock & feature;
1166
1167 /* are we changing a locked feature? */
1168 if (old_lock && (new_feature != old_feature)) {
1169 audit_log_feature_change(i, old_feature, new_feature,
1170 old_lock, new_lock, 0);
1171 return -EPERM;
1172 }
1173 }
1174 /* nothing invalid, do the changes */
1175 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1176 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1177 u32 old_feature, new_feature, old_lock, new_lock;
1178
1179 /* if we are not changing this feature, move along */
1180 if (!(feature & uaf->mask))
1181 continue;
1182
1183 old_feature = af.features & feature;
1184 new_feature = uaf->features & feature;
1185 old_lock = af.lock & feature;
1186 new_lock = (uaf->lock | af.lock) & feature;
1187
1188 if (new_feature != old_feature)
1189 audit_log_feature_change(i, old_feature, new_feature,
1190 old_lock, new_lock, 1);
1191
1192 if (new_feature)
1193 af.features |= feature;
1194 else
1195 af.features &= ~feature;
1196 af.lock |= new_lock;
1197 }
1198
1199 return 0;
1200 }
1201
audit_replace(struct pid * pid)1202 static int audit_replace(struct pid *pid)
1203 {
1204 pid_t pvnr;
1205 struct sk_buff *skb;
1206
1207 pvnr = pid_vnr(pid);
1208 skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1209 if (!skb)
1210 return -ENOMEM;
1211 return auditd_send_unicast_skb(skb);
1212 }
1213
audit_receive_msg(struct sk_buff * skb,struct nlmsghdr * nlh,bool * ack)1214 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
1215 bool *ack)
1216 {
1217 u32 seq;
1218 void *data;
1219 int data_len;
1220 int err;
1221 struct audit_buffer *ab;
1222 u16 msg_type = nlh->nlmsg_type;
1223 struct audit_sig_info *sig_data;
1224 char *ctx = NULL;
1225 u32 len;
1226
1227 err = audit_netlink_ok(skb, msg_type);
1228 if (err)
1229 return err;
1230
1231 seq = nlh->nlmsg_seq;
1232 data = nlmsg_data(nlh);
1233 data_len = nlmsg_len(nlh);
1234
1235 switch (msg_type) {
1236 case AUDIT_GET: {
1237 struct audit_status s;
1238 memset(&s, 0, sizeof(s));
1239 s.enabled = audit_enabled;
1240 s.failure = audit_failure;
1241 /* NOTE: use pid_vnr() so the PID is relative to the current
1242 * namespace */
1243 s.pid = auditd_pid_vnr();
1244 s.rate_limit = audit_rate_limit;
1245 s.backlog_limit = audit_backlog_limit;
1246 s.lost = atomic_read(&audit_lost);
1247 s.backlog = skb_queue_len(&audit_queue);
1248 s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL;
1249 s.backlog_wait_time = audit_backlog_wait_time;
1250 s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1251 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1252 break;
1253 }
1254 case AUDIT_SET: {
1255 struct audit_status s;
1256 memset(&s, 0, sizeof(s));
1257 /* guard against past and future API changes */
1258 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1259 if (s.mask & AUDIT_STATUS_ENABLED) {
1260 err = audit_set_enabled(s.enabled);
1261 if (err < 0)
1262 return err;
1263 }
1264 if (s.mask & AUDIT_STATUS_FAILURE) {
1265 err = audit_set_failure(s.failure);
1266 if (err < 0)
1267 return err;
1268 }
1269 if (s.mask & AUDIT_STATUS_PID) {
1270 /* NOTE: we are using the vnr PID functions below
1271 * because the s.pid value is relative to the
1272 * namespace of the caller; at present this
1273 * doesn't matter much since you can really only
1274 * run auditd from the initial pid namespace, but
1275 * something to keep in mind if this changes */
1276 pid_t new_pid = s.pid;
1277 pid_t auditd_pid;
1278 struct pid *req_pid = task_tgid(current);
1279
1280 /* Sanity check - PID values must match. Setting
1281 * pid to 0 is how auditd ends auditing. */
1282 if (new_pid && (new_pid != pid_vnr(req_pid)))
1283 return -EINVAL;
1284
1285 /* test the auditd connection */
1286 audit_replace(req_pid);
1287
1288 auditd_pid = auditd_pid_vnr();
1289 if (auditd_pid) {
1290 /* replacing a healthy auditd is not allowed */
1291 if (new_pid) {
1292 audit_log_config_change("audit_pid",
1293 new_pid, auditd_pid, 0);
1294 return -EEXIST;
1295 }
1296 /* only current auditd can unregister itself */
1297 if (pid_vnr(req_pid) != auditd_pid) {
1298 audit_log_config_change("audit_pid",
1299 new_pid, auditd_pid, 0);
1300 return -EACCES;
1301 }
1302 }
1303
1304 if (new_pid) {
1305 /* register a new auditd connection */
1306 err = auditd_set(req_pid,
1307 NETLINK_CB(skb).portid,
1308 sock_net(NETLINK_CB(skb).sk),
1309 skb, ack);
1310 if (audit_enabled != AUDIT_OFF)
1311 audit_log_config_change("audit_pid",
1312 new_pid,
1313 auditd_pid,
1314 err ? 0 : 1);
1315 if (err)
1316 return err;
1317
1318 /* try to process any backlog */
1319 wake_up_interruptible(&kauditd_wait);
1320 } else {
1321 if (audit_enabled != AUDIT_OFF)
1322 audit_log_config_change("audit_pid",
1323 new_pid,
1324 auditd_pid, 1);
1325
1326 /* unregister the auditd connection */
1327 auditd_reset(NULL);
1328 }
1329 }
1330 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1331 err = audit_set_rate_limit(s.rate_limit);
1332 if (err < 0)
1333 return err;
1334 }
1335 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1336 err = audit_set_backlog_limit(s.backlog_limit);
1337 if (err < 0)
1338 return err;
1339 }
1340 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1341 if (sizeof(s) > (size_t)nlh->nlmsg_len)
1342 return -EINVAL;
1343 if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1344 return -EINVAL;
1345 err = audit_set_backlog_wait_time(s.backlog_wait_time);
1346 if (err < 0)
1347 return err;
1348 }
1349 if (s.mask == AUDIT_STATUS_LOST) {
1350 u32 lost = atomic_xchg(&audit_lost, 0);
1351
1352 audit_log_config_change("lost", 0, lost, 1);
1353 return lost;
1354 }
1355 if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1356 u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1357
1358 audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1359 return actual;
1360 }
1361 break;
1362 }
1363 case AUDIT_GET_FEATURE:
1364 err = audit_get_feature(skb);
1365 if (err)
1366 return err;
1367 break;
1368 case AUDIT_SET_FEATURE:
1369 if (data_len < sizeof(struct audit_features))
1370 return -EINVAL;
1371 err = audit_set_feature(data);
1372 if (err)
1373 return err;
1374 break;
1375 case AUDIT_USER:
1376 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1377 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1378 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1379 return 0;
1380 /* exit early if there isn't at least one character to print */
1381 if (data_len < 2)
1382 return -EINVAL;
1383
1384 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1385 if (err == 1) { /* match or error */
1386 char *str = data;
1387
1388 err = 0;
1389 if (msg_type == AUDIT_USER_TTY) {
1390 err = tty_audit_push();
1391 if (err)
1392 break;
1393 }
1394 audit_log_user_recv_msg(&ab, msg_type);
1395 if (msg_type != AUDIT_USER_TTY) {
1396 /* ensure NULL termination */
1397 str[data_len - 1] = '\0';
1398 audit_log_format(ab, " msg='%.*s'",
1399 AUDIT_MESSAGE_TEXT_MAX,
1400 str);
1401 } else {
1402 audit_log_format(ab, " data=");
1403 if (str[data_len - 1] == '\0')
1404 data_len--;
1405 audit_log_n_untrustedstring(ab, str, data_len);
1406 }
1407 audit_log_end(ab);
1408 }
1409 break;
1410 case AUDIT_ADD_RULE:
1411 case AUDIT_DEL_RULE:
1412 if (data_len < sizeof(struct audit_rule_data))
1413 return -EINVAL;
1414 if (audit_enabled == AUDIT_LOCKED) {
1415 audit_log_common_recv_msg(audit_context(), &ab,
1416 AUDIT_CONFIG_CHANGE);
1417 audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1418 msg_type == AUDIT_ADD_RULE ?
1419 "add_rule" : "remove_rule",
1420 audit_enabled);
1421 audit_log_end(ab);
1422 return -EPERM;
1423 }
1424 err = audit_rule_change(msg_type, seq, data, data_len);
1425 break;
1426 case AUDIT_LIST_RULES:
1427 err = audit_list_rules_send(skb, seq);
1428 break;
1429 case AUDIT_TRIM:
1430 audit_trim_trees();
1431 audit_log_common_recv_msg(audit_context(), &ab,
1432 AUDIT_CONFIG_CHANGE);
1433 audit_log_format(ab, " op=trim res=1");
1434 audit_log_end(ab);
1435 break;
1436 case AUDIT_MAKE_EQUIV: {
1437 void *bufp = data;
1438 u32 sizes[2];
1439 size_t msglen = data_len;
1440 char *old, *new;
1441
1442 err = -EINVAL;
1443 if (msglen < 2 * sizeof(u32))
1444 break;
1445 memcpy(sizes, bufp, 2 * sizeof(u32));
1446 bufp += 2 * sizeof(u32);
1447 msglen -= 2 * sizeof(u32);
1448 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1449 if (IS_ERR(old)) {
1450 err = PTR_ERR(old);
1451 break;
1452 }
1453 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1454 if (IS_ERR(new)) {
1455 err = PTR_ERR(new);
1456 kfree(old);
1457 break;
1458 }
1459 /* OK, here comes... */
1460 err = audit_tag_tree(old, new);
1461
1462 audit_log_common_recv_msg(audit_context(), &ab,
1463 AUDIT_CONFIG_CHANGE);
1464 audit_log_format(ab, " op=make_equiv old=");
1465 audit_log_untrustedstring(ab, old);
1466 audit_log_format(ab, " new=");
1467 audit_log_untrustedstring(ab, new);
1468 audit_log_format(ab, " res=%d", !err);
1469 audit_log_end(ab);
1470 kfree(old);
1471 kfree(new);
1472 break;
1473 }
1474 case AUDIT_SIGNAL_INFO:
1475 len = 0;
1476 if (lsmprop_is_set(&audit_sig_lsm)) {
1477 err = security_lsmprop_to_secctx(&audit_sig_lsm, &ctx,
1478 &len);
1479 if (err)
1480 return err;
1481 }
1482 sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL);
1483 if (!sig_data) {
1484 if (lsmprop_is_set(&audit_sig_lsm))
1485 security_release_secctx(ctx, len);
1486 return -ENOMEM;
1487 }
1488 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1489 sig_data->pid = audit_sig_pid;
1490 if (lsmprop_is_set(&audit_sig_lsm)) {
1491 memcpy(sig_data->ctx, ctx, len);
1492 security_release_secctx(ctx, len);
1493 }
1494 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1495 sig_data, struct_size(sig_data, ctx, len));
1496 kfree(sig_data);
1497 break;
1498 case AUDIT_TTY_GET: {
1499 struct audit_tty_status s;
1500 unsigned int t;
1501
1502 t = READ_ONCE(current->signal->audit_tty);
1503 s.enabled = t & AUDIT_TTY_ENABLE;
1504 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1505
1506 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1507 break;
1508 }
1509 case AUDIT_TTY_SET: {
1510 struct audit_tty_status s, old;
1511 struct audit_buffer *ab;
1512 unsigned int t;
1513
1514 memset(&s, 0, sizeof(s));
1515 /* guard against past and future API changes */
1516 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1517 /* check if new data is valid */
1518 if ((s.enabled != 0 && s.enabled != 1) ||
1519 (s.log_passwd != 0 && s.log_passwd != 1))
1520 err = -EINVAL;
1521
1522 if (err)
1523 t = READ_ONCE(current->signal->audit_tty);
1524 else {
1525 t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1526 t = xchg(¤t->signal->audit_tty, t);
1527 }
1528 old.enabled = t & AUDIT_TTY_ENABLE;
1529 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1530
1531 audit_log_common_recv_msg(audit_context(), &ab,
1532 AUDIT_CONFIG_CHANGE);
1533 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1534 " old-log_passwd=%d new-log_passwd=%d res=%d",
1535 old.enabled, s.enabled, old.log_passwd,
1536 s.log_passwd, !err);
1537 audit_log_end(ab);
1538 break;
1539 }
1540 default:
1541 err = -EINVAL;
1542 break;
1543 }
1544
1545 return err < 0 ? err : 0;
1546 }
1547
1548 /**
1549 * audit_receive - receive messages from a netlink control socket
1550 * @skb: the message buffer
1551 *
1552 * Parse the provided skb and deal with any messages that may be present,
1553 * malformed skbs are discarded.
1554 */
audit_receive(struct sk_buff * skb)1555 static void audit_receive(struct sk_buff *skb)
1556 {
1557 struct nlmsghdr *nlh;
1558 bool ack;
1559 /*
1560 * len MUST be signed for nlmsg_next to be able to dec it below 0
1561 * if the nlmsg_len was not aligned
1562 */
1563 int len;
1564 int err;
1565
1566 nlh = nlmsg_hdr(skb);
1567 len = skb->len;
1568
1569 audit_ctl_lock();
1570 while (nlmsg_ok(nlh, len)) {
1571 ack = nlh->nlmsg_flags & NLM_F_ACK;
1572 err = audit_receive_msg(skb, nlh, &ack);
1573
1574 /* send an ack if the user asked for one and audit_receive_msg
1575 * didn't already do it, or if there was an error. */
1576 if (ack || err)
1577 netlink_ack(skb, nlh, err, NULL);
1578
1579 nlh = nlmsg_next(nlh, &len);
1580 }
1581 audit_ctl_unlock();
1582
1583 /* can't block with the ctrl lock, so penalize the sender now */
1584 if (audit_backlog_limit &&
1585 (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1586 DECLARE_WAITQUEUE(wait, current);
1587
1588 /* wake kauditd to try and flush the queue */
1589 wake_up_interruptible(&kauditd_wait);
1590
1591 add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1592 set_current_state(TASK_UNINTERRUPTIBLE);
1593 schedule_timeout(audit_backlog_wait_time);
1594 remove_wait_queue(&audit_backlog_wait, &wait);
1595 }
1596 }
1597
1598 /* Log information about who is connecting to the audit multicast socket */
audit_log_multicast(int group,const char * op,int err)1599 static void audit_log_multicast(int group, const char *op, int err)
1600 {
1601 const struct cred *cred;
1602 struct tty_struct *tty;
1603 char comm[sizeof(current->comm)];
1604 struct audit_buffer *ab;
1605
1606 if (!audit_enabled)
1607 return;
1608
1609 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1610 if (!ab)
1611 return;
1612
1613 cred = current_cred();
1614 tty = audit_get_tty();
1615 audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1616 task_tgid_nr(current),
1617 from_kuid(&init_user_ns, cred->uid),
1618 from_kuid(&init_user_ns, audit_get_loginuid(current)),
1619 tty ? tty_name(tty) : "(none)",
1620 audit_get_sessionid(current));
1621 audit_put_tty(tty);
1622 audit_log_task_context(ab); /* subj= */
1623 audit_log_format(ab, " comm=");
1624 audit_log_untrustedstring(ab, get_task_comm(comm, current));
1625 audit_log_d_path_exe(ab, current->mm); /* exe= */
1626 audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1627 audit_log_end(ab);
1628 }
1629
1630 /* Run custom bind function on netlink socket group connect or bind requests. */
audit_multicast_bind(struct net * net,int group)1631 static int audit_multicast_bind(struct net *net, int group)
1632 {
1633 int err = 0;
1634
1635 if (!capable(CAP_AUDIT_READ))
1636 err = -EPERM;
1637 audit_log_multicast(group, "connect", err);
1638 return err;
1639 }
1640
audit_multicast_unbind(struct net * net,int group)1641 static void audit_multicast_unbind(struct net *net, int group)
1642 {
1643 audit_log_multicast(group, "disconnect", 0);
1644 }
1645
audit_net_init(struct net * net)1646 static int __net_init audit_net_init(struct net *net)
1647 {
1648 struct netlink_kernel_cfg cfg = {
1649 .input = audit_receive,
1650 .bind = audit_multicast_bind,
1651 .unbind = audit_multicast_unbind,
1652 .flags = NL_CFG_F_NONROOT_RECV,
1653 .groups = AUDIT_NLGRP_MAX,
1654 };
1655
1656 struct audit_net *aunet = net_generic(net, audit_net_id);
1657
1658 aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1659 if (aunet->sk == NULL) {
1660 audit_panic("cannot initialize netlink socket in namespace");
1661 return -ENOMEM;
1662 }
1663 /* limit the timeout in case auditd is blocked/stopped */
1664 aunet->sk->sk_sndtimeo = HZ / 10;
1665
1666 return 0;
1667 }
1668
audit_net_exit(struct net * net)1669 static void __net_exit audit_net_exit(struct net *net)
1670 {
1671 struct audit_net *aunet = net_generic(net, audit_net_id);
1672
1673 /* NOTE: you would think that we would want to check the auditd
1674 * connection and potentially reset it here if it lives in this
1675 * namespace, but since the auditd connection tracking struct holds a
1676 * reference to this namespace (see auditd_set()) we are only ever
1677 * going to get here after that connection has been released */
1678
1679 netlink_kernel_release(aunet->sk);
1680 }
1681
1682 static struct pernet_operations audit_net_ops __net_initdata = {
1683 .init = audit_net_init,
1684 .exit = audit_net_exit,
1685 .id = &audit_net_id,
1686 .size = sizeof(struct audit_net),
1687 };
1688
1689 /* Initialize audit support at boot time. */
audit_init(void)1690 static int __init audit_init(void)
1691 {
1692 int i;
1693
1694 if (audit_initialized == AUDIT_DISABLED)
1695 return 0;
1696
1697 audit_buffer_cache = KMEM_CACHE(audit_buffer, SLAB_PANIC);
1698
1699 skb_queue_head_init(&audit_queue);
1700 skb_queue_head_init(&audit_retry_queue);
1701 skb_queue_head_init(&audit_hold_queue);
1702
1703 for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1704 INIT_LIST_HEAD(&audit_inode_hash[i]);
1705
1706 mutex_init(&audit_cmd_mutex.lock);
1707 audit_cmd_mutex.owner = NULL;
1708
1709 pr_info("initializing netlink subsys (%s)\n",
1710 str_enabled_disabled(audit_default));
1711 register_pernet_subsys(&audit_net_ops);
1712
1713 audit_initialized = AUDIT_INITIALIZED;
1714
1715 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1716 if (IS_ERR(kauditd_task)) {
1717 int err = PTR_ERR(kauditd_task);
1718 panic("audit: failed to start the kauditd thread (%d)\n", err);
1719 }
1720
1721 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1722 "state=initialized audit_enabled=%u res=1",
1723 audit_enabled);
1724
1725 return 0;
1726 }
1727 postcore_initcall(audit_init);
1728
1729 /*
1730 * Process kernel command-line parameter at boot time.
1731 * audit={0|off} or audit={1|on}.
1732 */
audit_enable(char * str)1733 static int __init audit_enable(char *str)
1734 {
1735 if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1736 audit_default = AUDIT_OFF;
1737 else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1738 audit_default = AUDIT_ON;
1739 else {
1740 pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1741 audit_default = AUDIT_ON;
1742 }
1743
1744 if (audit_default == AUDIT_OFF)
1745 audit_initialized = AUDIT_DISABLED;
1746 if (audit_set_enabled(audit_default))
1747 pr_err("audit: error setting audit state (%d)\n",
1748 audit_default);
1749
1750 pr_info("%s\n", audit_default ?
1751 "enabled (after initialization)" : "disabled (until reboot)");
1752
1753 return 1;
1754 }
1755 __setup("audit=", audit_enable);
1756
1757 /* Process kernel command-line parameter at boot time.
1758 * audit_backlog_limit=<n> */
audit_backlog_limit_set(char * str)1759 static int __init audit_backlog_limit_set(char *str)
1760 {
1761 u32 audit_backlog_limit_arg;
1762
1763 pr_info("audit_backlog_limit: ");
1764 if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1765 pr_cont("using default of %u, unable to parse %s\n",
1766 audit_backlog_limit, str);
1767 return 1;
1768 }
1769
1770 audit_backlog_limit = audit_backlog_limit_arg;
1771 pr_cont("%d\n", audit_backlog_limit);
1772
1773 return 1;
1774 }
1775 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1776
audit_buffer_free(struct audit_buffer * ab)1777 static void audit_buffer_free(struct audit_buffer *ab)
1778 {
1779 if (!ab)
1780 return;
1781
1782 kfree_skb(ab->skb);
1783 kmem_cache_free(audit_buffer_cache, ab);
1784 }
1785
audit_buffer_alloc(struct audit_context * ctx,gfp_t gfp_mask,int type)1786 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1787 gfp_t gfp_mask, int type)
1788 {
1789 struct audit_buffer *ab;
1790
1791 ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1792 if (!ab)
1793 return NULL;
1794
1795 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1796 if (!ab->skb)
1797 goto err;
1798 if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1799 goto err;
1800
1801 ab->ctx = ctx;
1802 ab->gfp_mask = gfp_mask;
1803
1804 return ab;
1805
1806 err:
1807 audit_buffer_free(ab);
1808 return NULL;
1809 }
1810
1811 /**
1812 * audit_serial - compute a serial number for the audit record
1813 *
1814 * Compute a serial number for the audit record. Audit records are
1815 * written to user-space as soon as they are generated, so a complete
1816 * audit record may be written in several pieces. The timestamp of the
1817 * record and this serial number are used by the user-space tools to
1818 * determine which pieces belong to the same audit record. The
1819 * (timestamp,serial) tuple is unique for each syscall and is live from
1820 * syscall entry to syscall exit.
1821 *
1822 * NOTE: Another possibility is to store the formatted records off the
1823 * audit context (for those records that have a context), and emit them
1824 * all at syscall exit. However, this could delay the reporting of
1825 * significant errors until syscall exit (or never, if the system
1826 * halts).
1827 */
audit_serial(void)1828 unsigned int audit_serial(void)
1829 {
1830 static atomic_t serial = ATOMIC_INIT(0);
1831
1832 return atomic_inc_return(&serial);
1833 }
1834
audit_get_stamp(struct audit_context * ctx,struct timespec64 * t,unsigned int * serial)1835 static inline void audit_get_stamp(struct audit_context *ctx,
1836 struct timespec64 *t, unsigned int *serial)
1837 {
1838 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1839 ktime_get_coarse_real_ts64(t);
1840 *serial = audit_serial();
1841 }
1842 }
1843
1844 /**
1845 * audit_log_start - obtain an audit buffer
1846 * @ctx: audit_context (may be NULL)
1847 * @gfp_mask: type of allocation
1848 * @type: audit message type
1849 *
1850 * Returns audit_buffer pointer on success or NULL on error.
1851 *
1852 * Obtain an audit buffer. This routine does locking to obtain the
1853 * audit buffer, but then no locking is required for calls to
1854 * audit_log_*format. If the task (ctx) is a task that is currently in a
1855 * syscall, then the syscall is marked as auditable and an audit record
1856 * will be written at syscall exit. If there is no associated task, then
1857 * task context (ctx) should be NULL.
1858 */
audit_log_start(struct audit_context * ctx,gfp_t gfp_mask,int type)1859 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1860 int type)
1861 {
1862 struct audit_buffer *ab;
1863 struct timespec64 t;
1864 unsigned int serial;
1865
1866 if (audit_initialized != AUDIT_INITIALIZED)
1867 return NULL;
1868
1869 if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1870 return NULL;
1871
1872 /* NOTE: don't ever fail/sleep on these two conditions:
1873 * 1. auditd generated record - since we need auditd to drain the
1874 * queue; also, when we are checking for auditd, compare PIDs using
1875 * task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1876 * using a PID anchored in the caller's namespace
1877 * 2. generator holding the audit_cmd_mutex - we don't want to block
1878 * while holding the mutex, although we do penalize the sender
1879 * later in audit_receive() when it is safe to block
1880 */
1881 if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1882 long stime = audit_backlog_wait_time;
1883
1884 while (audit_backlog_limit &&
1885 (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1886 /* wake kauditd to try and flush the queue */
1887 wake_up_interruptible(&kauditd_wait);
1888
1889 /* sleep if we are allowed and we haven't exhausted our
1890 * backlog wait limit */
1891 if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1892 long rtime = stime;
1893
1894 DECLARE_WAITQUEUE(wait, current);
1895
1896 add_wait_queue_exclusive(&audit_backlog_wait,
1897 &wait);
1898 set_current_state(TASK_UNINTERRUPTIBLE);
1899 stime = schedule_timeout(rtime);
1900 atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1901 remove_wait_queue(&audit_backlog_wait, &wait);
1902 } else {
1903 if (audit_rate_check() && printk_ratelimit())
1904 pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1905 skb_queue_len(&audit_queue),
1906 audit_backlog_limit);
1907 audit_log_lost("backlog limit exceeded");
1908 return NULL;
1909 }
1910 }
1911 }
1912
1913 ab = audit_buffer_alloc(ctx, gfp_mask, type);
1914 if (!ab) {
1915 audit_log_lost("out of memory in audit_log_start");
1916 return NULL;
1917 }
1918
1919 audit_get_stamp(ab->ctx, &t, &serial);
1920 /* cancel dummy context to enable supporting records */
1921 if (ctx)
1922 ctx->dummy = 0;
1923 audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1924 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1925
1926 return ab;
1927 }
1928
1929 /**
1930 * audit_expand - expand skb in the audit buffer
1931 * @ab: audit_buffer
1932 * @extra: space to add at tail of the skb
1933 *
1934 * Returns 0 (no space) on failed expansion, or available space if
1935 * successful.
1936 */
audit_expand(struct audit_buffer * ab,int extra)1937 static inline int audit_expand(struct audit_buffer *ab, int extra)
1938 {
1939 struct sk_buff *skb = ab->skb;
1940 int oldtail = skb_tailroom(skb);
1941 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1942 int newtail = skb_tailroom(skb);
1943
1944 if (ret < 0) {
1945 audit_log_lost("out of memory in audit_expand");
1946 return 0;
1947 }
1948
1949 skb->truesize += newtail - oldtail;
1950 return newtail;
1951 }
1952
1953 /*
1954 * Format an audit message into the audit buffer. If there isn't enough
1955 * room in the audit buffer, more room will be allocated and vsnprint
1956 * will be called a second time. Currently, we assume that a printk
1957 * can't format message larger than 1024 bytes, so we don't either.
1958 */
audit_log_vformat(struct audit_buffer * ab,const char * fmt,va_list args)1959 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1960 va_list args)
1961 {
1962 int len, avail;
1963 struct sk_buff *skb;
1964 va_list args2;
1965
1966 if (!ab)
1967 return;
1968
1969 BUG_ON(!ab->skb);
1970 skb = ab->skb;
1971 avail = skb_tailroom(skb);
1972 if (avail == 0) {
1973 avail = audit_expand(ab, AUDIT_BUFSIZ);
1974 if (!avail)
1975 goto out;
1976 }
1977 va_copy(args2, args);
1978 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1979 if (len >= avail) {
1980 /* The printk buffer is 1024 bytes long, so if we get
1981 * here and AUDIT_BUFSIZ is at least 1024, then we can
1982 * log everything that printk could have logged. */
1983 avail = audit_expand(ab,
1984 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1985 if (!avail)
1986 goto out_va_end;
1987 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1988 }
1989 if (len > 0)
1990 skb_put(skb, len);
1991 out_va_end:
1992 va_end(args2);
1993 out:
1994 return;
1995 }
1996
1997 /**
1998 * audit_log_format - format a message into the audit buffer.
1999 * @ab: audit_buffer
2000 * @fmt: format string
2001 * @...: optional parameters matching @fmt string
2002 *
2003 * All the work is done in audit_log_vformat.
2004 */
audit_log_format(struct audit_buffer * ab,const char * fmt,...)2005 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
2006 {
2007 va_list args;
2008
2009 if (!ab)
2010 return;
2011 va_start(args, fmt);
2012 audit_log_vformat(ab, fmt, args);
2013 va_end(args);
2014 }
2015
2016 /**
2017 * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
2018 * @ab: the audit_buffer
2019 * @buf: buffer to convert to hex
2020 * @len: length of @buf to be converted
2021 *
2022 * No return value; failure to expand is silently ignored.
2023 *
2024 * This function will take the passed buf and convert it into a string of
2025 * ascii hex digits. The new string is placed onto the skb.
2026 */
audit_log_n_hex(struct audit_buffer * ab,const unsigned char * buf,size_t len)2027 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
2028 size_t len)
2029 {
2030 int i, avail, new_len;
2031 unsigned char *ptr;
2032 struct sk_buff *skb;
2033
2034 if (!ab)
2035 return;
2036
2037 BUG_ON(!ab->skb);
2038 skb = ab->skb;
2039 avail = skb_tailroom(skb);
2040 new_len = len<<1;
2041 if (new_len >= avail) {
2042 /* Round the buffer request up to the next multiple */
2043 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2044 avail = audit_expand(ab, new_len);
2045 if (!avail)
2046 return;
2047 }
2048
2049 ptr = skb_tail_pointer(skb);
2050 for (i = 0; i < len; i++)
2051 ptr = hex_byte_pack_upper(ptr, buf[i]);
2052 *ptr = 0;
2053 skb_put(skb, len << 1); /* new string is twice the old string */
2054 }
2055
2056 /*
2057 * Format a string of no more than slen characters into the audit buffer,
2058 * enclosed in quote marks.
2059 */
audit_log_n_string(struct audit_buffer * ab,const char * string,size_t slen)2060 void audit_log_n_string(struct audit_buffer *ab, const char *string,
2061 size_t slen)
2062 {
2063 int avail, new_len;
2064 unsigned char *ptr;
2065 struct sk_buff *skb;
2066
2067 if (!ab)
2068 return;
2069
2070 BUG_ON(!ab->skb);
2071 skb = ab->skb;
2072 avail = skb_tailroom(skb);
2073 new_len = slen + 3; /* enclosing quotes + null terminator */
2074 if (new_len > avail) {
2075 avail = audit_expand(ab, new_len);
2076 if (!avail)
2077 return;
2078 }
2079 ptr = skb_tail_pointer(skb);
2080 *ptr++ = '"';
2081 memcpy(ptr, string, slen);
2082 ptr += slen;
2083 *ptr++ = '"';
2084 *ptr = 0;
2085 skb_put(skb, slen + 2); /* don't include null terminator */
2086 }
2087
2088 /**
2089 * audit_string_contains_control - does a string need to be logged in hex
2090 * @string: string to be checked
2091 * @len: max length of the string to check
2092 */
audit_string_contains_control(const char * string,size_t len)2093 bool audit_string_contains_control(const char *string, size_t len)
2094 {
2095 const unsigned char *p;
2096 for (p = string; p < (const unsigned char *)string + len; p++) {
2097 if (*p == '"' || *p < 0x21 || *p > 0x7e)
2098 return true;
2099 }
2100 return false;
2101 }
2102
2103 /**
2104 * audit_log_n_untrustedstring - log a string that may contain random characters
2105 * @ab: audit_buffer
2106 * @string: string to be logged
2107 * @len: length of string (not including trailing null)
2108 *
2109 * This code will escape a string that is passed to it if the string
2110 * contains a control character, unprintable character, double quote mark,
2111 * or a space. Unescaped strings will start and end with a double quote mark.
2112 * Strings that are escaped are printed in hex (2 digits per char).
2113 *
2114 * The caller specifies the number of characters in the string to log, which may
2115 * or may not be the entire string.
2116 */
audit_log_n_untrustedstring(struct audit_buffer * ab,const char * string,size_t len)2117 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2118 size_t len)
2119 {
2120 if (audit_string_contains_control(string, len))
2121 audit_log_n_hex(ab, string, len);
2122 else
2123 audit_log_n_string(ab, string, len);
2124 }
2125
2126 /**
2127 * audit_log_untrustedstring - log a string that may contain random characters
2128 * @ab: audit_buffer
2129 * @string: string to be logged
2130 *
2131 * Same as audit_log_n_untrustedstring(), except that strlen is used to
2132 * determine string length.
2133 */
audit_log_untrustedstring(struct audit_buffer * ab,const char * string)2134 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2135 {
2136 audit_log_n_untrustedstring(ab, string, strlen(string));
2137 }
2138
2139 /* This is a helper-function to print the escaped d_path */
audit_log_d_path(struct audit_buffer * ab,const char * prefix,const struct path * path)2140 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2141 const struct path *path)
2142 {
2143 char *p, *pathname;
2144
2145 if (prefix)
2146 audit_log_format(ab, "%s", prefix);
2147
2148 /* We will allow 11 spaces for ' (deleted)' to be appended */
2149 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2150 if (!pathname) {
2151 audit_log_format(ab, "\"<no_memory>\"");
2152 return;
2153 }
2154 p = d_path(path, pathname, PATH_MAX+11);
2155 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2156 /* FIXME: can we save some information here? */
2157 audit_log_format(ab, "\"<too_long>\"");
2158 } else
2159 audit_log_untrustedstring(ab, p);
2160 kfree(pathname);
2161 }
2162
audit_log_session_info(struct audit_buffer * ab)2163 void audit_log_session_info(struct audit_buffer *ab)
2164 {
2165 unsigned int sessionid = audit_get_sessionid(current);
2166 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2167
2168 audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2169 }
2170
audit_log_key(struct audit_buffer * ab,char * key)2171 void audit_log_key(struct audit_buffer *ab, char *key)
2172 {
2173 audit_log_format(ab, " key=");
2174 if (key)
2175 audit_log_untrustedstring(ab, key);
2176 else
2177 audit_log_format(ab, "(null)");
2178 }
2179
audit_log_task_context(struct audit_buffer * ab)2180 int audit_log_task_context(struct audit_buffer *ab)
2181 {
2182 struct lsm_prop prop;
2183 char *ctx = NULL;
2184 unsigned len;
2185 int error;
2186
2187 security_current_getlsmprop_subj(&prop);
2188 if (!lsmprop_is_set(&prop))
2189 return 0;
2190
2191 error = security_lsmprop_to_secctx(&prop, &ctx, &len);
2192 if (error) {
2193 if (error != -EINVAL)
2194 goto error_path;
2195 return 0;
2196 }
2197
2198 audit_log_format(ab, " subj=%s", ctx);
2199 security_release_secctx(ctx, len);
2200 return 0;
2201
2202 error_path:
2203 audit_panic("error in audit_log_task_context");
2204 return error;
2205 }
2206 EXPORT_SYMBOL(audit_log_task_context);
2207
audit_log_d_path_exe(struct audit_buffer * ab,struct mm_struct * mm)2208 void audit_log_d_path_exe(struct audit_buffer *ab,
2209 struct mm_struct *mm)
2210 {
2211 struct file *exe_file;
2212
2213 if (!mm)
2214 goto out_null;
2215
2216 exe_file = get_mm_exe_file(mm);
2217 if (!exe_file)
2218 goto out_null;
2219
2220 audit_log_d_path(ab, " exe=", &exe_file->f_path);
2221 fput(exe_file);
2222 return;
2223 out_null:
2224 audit_log_format(ab, " exe=(null)");
2225 }
2226
audit_get_tty(void)2227 struct tty_struct *audit_get_tty(void)
2228 {
2229 struct tty_struct *tty = NULL;
2230 unsigned long flags;
2231
2232 spin_lock_irqsave(¤t->sighand->siglock, flags);
2233 if (current->signal)
2234 tty = tty_kref_get(current->signal->tty);
2235 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
2236 return tty;
2237 }
2238
audit_put_tty(struct tty_struct * tty)2239 void audit_put_tty(struct tty_struct *tty)
2240 {
2241 tty_kref_put(tty);
2242 }
2243
audit_log_task_info(struct audit_buffer * ab)2244 void audit_log_task_info(struct audit_buffer *ab)
2245 {
2246 const struct cred *cred;
2247 char comm[sizeof(current->comm)];
2248 struct tty_struct *tty;
2249
2250 if (!ab)
2251 return;
2252
2253 cred = current_cred();
2254 tty = audit_get_tty();
2255 audit_log_format(ab,
2256 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2257 " euid=%u suid=%u fsuid=%u"
2258 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2259 task_ppid_nr(current),
2260 task_tgid_nr(current),
2261 from_kuid(&init_user_ns, audit_get_loginuid(current)),
2262 from_kuid(&init_user_ns, cred->uid),
2263 from_kgid(&init_user_ns, cred->gid),
2264 from_kuid(&init_user_ns, cred->euid),
2265 from_kuid(&init_user_ns, cred->suid),
2266 from_kuid(&init_user_ns, cred->fsuid),
2267 from_kgid(&init_user_ns, cred->egid),
2268 from_kgid(&init_user_ns, cred->sgid),
2269 from_kgid(&init_user_ns, cred->fsgid),
2270 tty ? tty_name(tty) : "(none)",
2271 audit_get_sessionid(current));
2272 audit_put_tty(tty);
2273 audit_log_format(ab, " comm=");
2274 audit_log_untrustedstring(ab, get_task_comm(comm, current));
2275 audit_log_d_path_exe(ab, current->mm);
2276 audit_log_task_context(ab);
2277 }
2278 EXPORT_SYMBOL(audit_log_task_info);
2279
2280 /**
2281 * audit_log_path_denied - report a path restriction denial
2282 * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2283 * @operation: specific operation name
2284 */
audit_log_path_denied(int type,const char * operation)2285 void audit_log_path_denied(int type, const char *operation)
2286 {
2287 struct audit_buffer *ab;
2288
2289 if (!audit_enabled || audit_dummy_context())
2290 return;
2291
2292 /* Generate log with subject, operation, outcome. */
2293 ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2294 if (!ab)
2295 return;
2296 audit_log_format(ab, "op=%s", operation);
2297 audit_log_task_info(ab);
2298 audit_log_format(ab, " res=0");
2299 audit_log_end(ab);
2300 }
2301
2302 /* global counter which is incremented every time something logs in */
2303 static atomic_t session_id = ATOMIC_INIT(0);
2304
audit_set_loginuid_perm(kuid_t loginuid)2305 static int audit_set_loginuid_perm(kuid_t loginuid)
2306 {
2307 /* if we are unset, we don't need privs */
2308 if (!audit_loginuid_set(current))
2309 return 0;
2310 /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2311 if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2312 return -EPERM;
2313 /* it is set, you need permission */
2314 if (!capable(CAP_AUDIT_CONTROL))
2315 return -EPERM;
2316 /* reject if this is not an unset and we don't allow that */
2317 if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2318 && uid_valid(loginuid))
2319 return -EPERM;
2320 return 0;
2321 }
2322
audit_log_set_loginuid(kuid_t koldloginuid,kuid_t kloginuid,unsigned int oldsessionid,unsigned int sessionid,int rc)2323 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2324 unsigned int oldsessionid,
2325 unsigned int sessionid, int rc)
2326 {
2327 struct audit_buffer *ab;
2328 uid_t uid, oldloginuid, loginuid;
2329 struct tty_struct *tty;
2330
2331 if (!audit_enabled)
2332 return;
2333
2334 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2335 if (!ab)
2336 return;
2337
2338 uid = from_kuid(&init_user_ns, task_uid(current));
2339 oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2340 loginuid = from_kuid(&init_user_ns, kloginuid);
2341 tty = audit_get_tty();
2342
2343 audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2344 audit_log_task_context(ab);
2345 audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2346 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2347 oldsessionid, sessionid, !rc);
2348 audit_put_tty(tty);
2349 audit_log_end(ab);
2350 }
2351
2352 /**
2353 * audit_set_loginuid - set current task's loginuid
2354 * @loginuid: loginuid value
2355 *
2356 * Returns 0.
2357 *
2358 * Called (set) from fs/proc/base.c::proc_loginuid_write().
2359 */
audit_set_loginuid(kuid_t loginuid)2360 int audit_set_loginuid(kuid_t loginuid)
2361 {
2362 unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2363 kuid_t oldloginuid;
2364 int rc;
2365
2366 oldloginuid = audit_get_loginuid(current);
2367 oldsessionid = audit_get_sessionid(current);
2368
2369 rc = audit_set_loginuid_perm(loginuid);
2370 if (rc)
2371 goto out;
2372
2373 /* are we setting or clearing? */
2374 if (uid_valid(loginuid)) {
2375 sessionid = (unsigned int)atomic_inc_return(&session_id);
2376 if (unlikely(sessionid == AUDIT_SID_UNSET))
2377 sessionid = (unsigned int)atomic_inc_return(&session_id);
2378 }
2379
2380 current->sessionid = sessionid;
2381 current->loginuid = loginuid;
2382 out:
2383 audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2384 return rc;
2385 }
2386
2387 /**
2388 * audit_signal_info - record signal info for shutting down audit subsystem
2389 * @sig: signal value
2390 * @t: task being signaled
2391 *
2392 * If the audit subsystem is being terminated, record the task (pid)
2393 * and uid that is doing that.
2394 */
audit_signal_info(int sig,struct task_struct * t)2395 int audit_signal_info(int sig, struct task_struct *t)
2396 {
2397 kuid_t uid = current_uid(), auid;
2398
2399 if (auditd_test_task(t) &&
2400 (sig == SIGTERM || sig == SIGHUP ||
2401 sig == SIGUSR1 || sig == SIGUSR2)) {
2402 audit_sig_pid = task_tgid_nr(current);
2403 auid = audit_get_loginuid(current);
2404 if (uid_valid(auid))
2405 audit_sig_uid = auid;
2406 else
2407 audit_sig_uid = uid;
2408 security_current_getlsmprop_subj(&audit_sig_lsm);
2409 }
2410
2411 return audit_signal_info_syscall(t);
2412 }
2413
2414 /**
2415 * audit_log_end - end one audit record
2416 * @ab: the audit_buffer
2417 *
2418 * We can not do a netlink send inside an irq context because it blocks (last
2419 * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2420 * queue and a kthread is scheduled to remove them from the queue outside the
2421 * irq context. May be called in any context.
2422 */
audit_log_end(struct audit_buffer * ab)2423 void audit_log_end(struct audit_buffer *ab)
2424 {
2425 struct sk_buff *skb;
2426 struct nlmsghdr *nlh;
2427
2428 if (!ab)
2429 return;
2430
2431 if (audit_rate_check()) {
2432 skb = ab->skb;
2433 ab->skb = NULL;
2434
2435 /* setup the netlink header, see the comments in
2436 * kauditd_send_multicast_skb() for length quirks */
2437 nlh = nlmsg_hdr(skb);
2438 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2439
2440 /* queue the netlink packet and poke the kauditd thread */
2441 skb_queue_tail(&audit_queue, skb);
2442 wake_up_interruptible(&kauditd_wait);
2443 } else
2444 audit_log_lost("rate limit exceeded");
2445
2446 audit_buffer_free(ab);
2447 }
2448
2449 /**
2450 * audit_log - Log an audit record
2451 * @ctx: audit context
2452 * @gfp_mask: type of allocation
2453 * @type: audit message type
2454 * @fmt: format string to use
2455 * @...: variable parameters matching the format string
2456 *
2457 * This is a convenience function that calls audit_log_start,
2458 * audit_log_vformat, and audit_log_end. It may be called
2459 * in any context.
2460 */
audit_log(struct audit_context * ctx,gfp_t gfp_mask,int type,const char * fmt,...)2461 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2462 const char *fmt, ...)
2463 {
2464 struct audit_buffer *ab;
2465 va_list args;
2466
2467 ab = audit_log_start(ctx, gfp_mask, type);
2468 if (ab) {
2469 va_start(args, fmt);
2470 audit_log_vformat(ab, fmt, args);
2471 va_end(args);
2472 audit_log_end(ab);
2473 }
2474 }
2475
2476 EXPORT_SYMBOL(audit_log_start);
2477 EXPORT_SYMBOL(audit_log_end);
2478 EXPORT_SYMBOL(audit_log_format);
2479 EXPORT_SYMBOL(audit_log);
2480