xref: /linux/kernel/audit.c (revision 56a0810d8ca406648fe01ec996ade1d61bf8ec8d)
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/lsm_hooks.h>
58 #include <linux/freezer.h>
59 #include <linux/pid_namespace.h>
60 #include <net/netns/generic.h>
61 
62 #include "audit.h"
63 
64 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
65  * (Initialization happens after skb_init is called.) */
66 #define AUDIT_DISABLED		-1
67 #define AUDIT_UNINITIALIZED	0
68 #define AUDIT_INITIALIZED	1
69 static int	audit_initialized = AUDIT_UNINITIALIZED;
70 
71 u32		audit_enabled = AUDIT_OFF;
72 bool		audit_ever_enabled = !!AUDIT_OFF;
73 
74 EXPORT_SYMBOL_GPL(audit_enabled);
75 
76 /* Default state when kernel boots without any parameters. */
77 static u32	audit_default = AUDIT_OFF;
78 
79 /* If auditing cannot proceed, audit_failure selects what happens. */
80 static u32	audit_failure = AUDIT_FAIL_PRINTK;
81 
82 /* private audit network namespace index */
83 static unsigned int audit_net_id;
84 
85 /* Number of modules that provide a security context.
86    List of lsms that provide a security context */
87 static u32 audit_subj_secctx_cnt;
88 static u32 audit_obj_secctx_cnt;
89 static const struct lsm_id *audit_subj_lsms[MAX_LSM_COUNT];
90 static const struct lsm_id *audit_obj_lsms[MAX_LSM_COUNT];
91 
92 /**
93  * struct audit_net - audit private network namespace data
94  * @sk: communication socket
95  */
96 struct audit_net {
97 	struct sock *sk;
98 };
99 
100 /**
101  * struct auditd_connection - kernel/auditd connection state
102  * @pid: auditd PID
103  * @portid: netlink portid
104  * @net: the associated network namespace
105  * @rcu: RCU head
106  *
107  * Description:
108  * This struct is RCU protected; you must either hold the RCU lock for reading
109  * or the associated spinlock for writing.
110  */
111 struct auditd_connection {
112 	struct pid *pid;
113 	u32 portid;
114 	struct net *net;
115 	struct rcu_head rcu;
116 };
117 static struct auditd_connection __rcu *auditd_conn;
118 static DEFINE_SPINLOCK(auditd_conn_lock);
119 
120 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
121  * to that number per second.  This prevents DoS attacks, but results in
122  * audit records being dropped. */
123 static u32	audit_rate_limit;
124 
125 /* Number of outstanding audit_buffers allowed.
126  * When set to zero, this means unlimited. */
127 static u32	audit_backlog_limit = 64;
128 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
129 static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
130 
131 /* The identity of the user shutting down the audit system. */
132 static kuid_t		audit_sig_uid = INVALID_UID;
133 static pid_t		audit_sig_pid = -1;
134 static struct lsm_prop	audit_sig_lsm;
135 
136 /* Records can be lost in several ways:
137    0) [suppressed in audit_alloc]
138    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
139    2) out of memory in audit_log_move [alloc_skb]
140    3) suppressed due to audit_rate_limit
141    4) suppressed due to audit_backlog_limit
142 */
143 static atomic_t	audit_lost = ATOMIC_INIT(0);
144 
145 /* Monotonically increasing sum of time the kernel has spent
146  * waiting while the backlog limit is exceeded.
147  */
148 static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
149 
150 /* Hash for inode-based rules */
151 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
152 
153 static struct kmem_cache *audit_buffer_cache;
154 
155 /* queue msgs to send via kauditd_task */
156 static struct sk_buff_head audit_queue;
157 /* queue msgs due to temporary unicast send problems */
158 static struct sk_buff_head audit_retry_queue;
159 /* queue msgs waiting for new auditd connection */
160 static struct sk_buff_head audit_hold_queue;
161 
162 /* queue servicing thread */
163 static struct task_struct *kauditd_task;
164 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
165 
166 /* waitqueue for callers who are blocked on the audit backlog */
167 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
168 
169 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
170 				   .mask = -1,
171 				   .features = 0,
172 				   .lock = 0,};
173 
174 static char *audit_feature_names[2] = {
175 	"only_unset_loginuid",
176 	"loginuid_immutable",
177 };
178 
179 /**
180  * struct audit_ctl_mutex - serialize requests from userspace
181  * @lock: the mutex used for locking
182  * @owner: the task which owns the lock
183  *
184  * Description:
185  * This is the lock struct used to ensure we only process userspace requests
186  * in an orderly fashion.  We can't simply use a mutex/lock here because we
187  * need to track lock ownership so we don't end up blocking the lock owner in
188  * audit_log_start() or similar.
189  */
190 static struct audit_ctl_mutex {
191 	struct mutex lock;
192 	void *owner;
193 } audit_cmd_mutex;
194 
195 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
196  * audit records.  Since printk uses a 1024 byte buffer, this buffer
197  * should be at least that large. */
198 #define AUDIT_BUFSIZ 1024
199 
200 /* The audit_buffer is used when formatting an audit record.  The caller
201  * locks briefly to get the record off the freelist or to allocate the
202  * buffer, and locks briefly to send the buffer to the netlink layer or
203  * to place it on a transmit queue.  Multiple audit_buffers can be in
204  * use simultaneously. */
205 struct audit_buffer {
206 	struct sk_buff       *skb;	/* the skb for audit_log functions */
207 	struct sk_buff_head  skb_list;	/* formatted skbs, ready to send */
208 	struct audit_context *ctx;	/* NULL or associated context */
209 	struct audit_stamp   stamp;	/* audit stamp for these records */
210 	gfp_t		     gfp_mask;
211 };
212 
213 struct audit_reply {
214 	__u32 portid;
215 	struct net *net;
216 	struct sk_buff *skb;
217 };
218 
219 /**
220  * auditd_test_task - Check to see if a given task is an audit daemon
221  * @task: the task to check
222  *
223  * Description:
224  * Return 1 if the task is a registered audit daemon, 0 otherwise.
225  */
auditd_test_task(struct task_struct * task)226 int auditd_test_task(struct task_struct *task)
227 {
228 	int rc;
229 	struct auditd_connection *ac;
230 
231 	rcu_read_lock();
232 	ac = rcu_dereference(auditd_conn);
233 	rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
234 	rcu_read_unlock();
235 
236 	return rc;
237 }
238 
239 /**
240  * audit_ctl_lock - Take the audit control lock
241  */
audit_ctl_lock(void)242 void audit_ctl_lock(void)
243 {
244 	mutex_lock(&audit_cmd_mutex.lock);
245 	audit_cmd_mutex.owner = current;
246 }
247 
248 /**
249  * audit_ctl_unlock - Drop the audit control lock
250  */
audit_ctl_unlock(void)251 void audit_ctl_unlock(void)
252 {
253 	audit_cmd_mutex.owner = NULL;
254 	mutex_unlock(&audit_cmd_mutex.lock);
255 }
256 
257 /**
258  * audit_ctl_owner_current - Test to see if the current task owns the lock
259  *
260  * Description:
261  * Return true if the current task owns the audit control lock, false if it
262  * doesn't own the lock.
263  */
audit_ctl_owner_current(void)264 static bool audit_ctl_owner_current(void)
265 {
266 	return (current == audit_cmd_mutex.owner);
267 }
268 
269 /**
270  * auditd_pid_vnr - Return the auditd PID relative to the namespace
271  *
272  * Description:
273  * Returns the PID in relation to the namespace, 0 on failure.
274  */
auditd_pid_vnr(void)275 static pid_t auditd_pid_vnr(void)
276 {
277 	pid_t pid;
278 	const struct auditd_connection *ac;
279 
280 	rcu_read_lock();
281 	ac = rcu_dereference(auditd_conn);
282 	if (!ac || !ac->pid)
283 		pid = 0;
284 	else
285 		pid = pid_vnr(ac->pid);
286 	rcu_read_unlock();
287 
288 	return pid;
289 }
290 
291 /**
292  * audit_cfg_lsm - Identify a security module as providing a secctx.
293  * @lsmid: LSM identity
294  * @flags: which contexts are provided
295  *
296  * Description:
297  * Increments the count of the security modules providing a secctx.
298  * If the LSM id is already in the list leave it alone.
299  */
audit_cfg_lsm(const struct lsm_id * lsmid,int flags)300 void audit_cfg_lsm(const struct lsm_id *lsmid, int flags)
301 {
302 	int i;
303 
304 	if (flags & AUDIT_CFG_LSM_SECCTX_SUBJECT) {
305 		for (i = 0 ; i < audit_subj_secctx_cnt; i++)
306 			if (audit_subj_lsms[i] == lsmid)
307 				return;
308 		audit_subj_lsms[audit_subj_secctx_cnt++] = lsmid;
309 	}
310 	if (flags & AUDIT_CFG_LSM_SECCTX_OBJECT) {
311 		for (i = 0 ; i < audit_obj_secctx_cnt; i++)
312 			if (audit_obj_lsms[i] == lsmid)
313 				return;
314 		audit_obj_lsms[audit_obj_secctx_cnt++] = lsmid;
315 	}
316 }
317 
318 /**
319  * audit_get_sk - Return the audit socket for the given network namespace
320  * @net: the destination network namespace
321  *
322  * Description:
323  * Returns the sock pointer if valid, NULL otherwise.  The caller must ensure
324  * that a reference is held for the network namespace while the sock is in use.
325  */
audit_get_sk(const struct net * net)326 static struct sock *audit_get_sk(const struct net *net)
327 {
328 	struct audit_net *aunet;
329 
330 	if (!net)
331 		return NULL;
332 
333 	aunet = net_generic(net, audit_net_id);
334 	return aunet->sk;
335 }
336 
audit_panic(const char * message)337 void audit_panic(const char *message)
338 {
339 	switch (audit_failure) {
340 	case AUDIT_FAIL_SILENT:
341 		break;
342 	case AUDIT_FAIL_PRINTK:
343 		if (printk_ratelimit())
344 			pr_err("%s\n", message);
345 		break;
346 	case AUDIT_FAIL_PANIC:
347 		panic("audit: %s\n", message);
348 		break;
349 	}
350 }
351 
audit_rate_check(void)352 static inline int audit_rate_check(void)
353 {
354 	static unsigned long	last_check = 0;
355 	static int		messages   = 0;
356 	static DEFINE_SPINLOCK(lock);
357 	unsigned long		flags;
358 	unsigned long		now;
359 	int			retval	   = 0;
360 
361 	if (!audit_rate_limit)
362 		return 1;
363 
364 	spin_lock_irqsave(&lock, flags);
365 	if (++messages < audit_rate_limit) {
366 		retval = 1;
367 	} else {
368 		now = jiffies;
369 		if (time_after(now, last_check + HZ)) {
370 			last_check = now;
371 			messages   = 0;
372 			retval     = 1;
373 		}
374 	}
375 	spin_unlock_irqrestore(&lock, flags);
376 
377 	return retval;
378 }
379 
380 /**
381  * audit_log_lost - conditionally log lost audit message event
382  * @message: the message stating reason for lost audit message
383  *
384  * Emit at least 1 message per second, even if audit_rate_check is
385  * throttling.
386  * Always increment the lost messages counter.
387 */
audit_log_lost(const char * message)388 void audit_log_lost(const char *message)
389 {
390 	static unsigned long	last_msg = 0;
391 	static DEFINE_SPINLOCK(lock);
392 	unsigned long		flags;
393 	unsigned long		now;
394 	int			print;
395 
396 	atomic_inc(&audit_lost);
397 
398 	print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
399 
400 	if (!print) {
401 		spin_lock_irqsave(&lock, flags);
402 		now = jiffies;
403 		if (time_after(now, last_msg + HZ)) {
404 			print = 1;
405 			last_msg = now;
406 		}
407 		spin_unlock_irqrestore(&lock, flags);
408 	}
409 
410 	if (print) {
411 		if (printk_ratelimit())
412 			pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
413 				atomic_read(&audit_lost),
414 				audit_rate_limit,
415 				audit_backlog_limit);
416 		audit_panic(message);
417 	}
418 }
419 
audit_log_config_change(char * function_name,u32 new,u32 old,int allow_changes)420 static int audit_log_config_change(char *function_name, u32 new, u32 old,
421 				   int allow_changes)
422 {
423 	struct audit_buffer *ab;
424 	int rc = 0;
425 
426 	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
427 	if (unlikely(!ab))
428 		return rc;
429 	audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
430 	audit_log_session_info(ab);
431 	rc = audit_log_task_context(ab);
432 	if (rc)
433 		allow_changes = 0; /* Something weird, deny request */
434 	audit_log_format(ab, " res=%d", allow_changes);
435 	audit_log_end(ab);
436 	return rc;
437 }
438 
audit_do_config_change(char * function_name,u32 * to_change,u32 new)439 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
440 {
441 	int allow_changes, rc = 0;
442 	u32 old = *to_change;
443 
444 	/* check if we are locked */
445 	if (audit_enabled == AUDIT_LOCKED)
446 		allow_changes = 0;
447 	else
448 		allow_changes = 1;
449 
450 	if (audit_enabled != AUDIT_OFF) {
451 		rc = audit_log_config_change(function_name, new, old, allow_changes);
452 		if (rc)
453 			allow_changes = 0;
454 	}
455 
456 	/* If we are allowed, make the change */
457 	if (allow_changes == 1)
458 		*to_change = new;
459 	/* Not allowed, update reason */
460 	else if (rc == 0)
461 		rc = -EPERM;
462 	return rc;
463 }
464 
audit_set_rate_limit(u32 limit)465 static int audit_set_rate_limit(u32 limit)
466 {
467 	return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
468 }
469 
audit_set_backlog_limit(u32 limit)470 static int audit_set_backlog_limit(u32 limit)
471 {
472 	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
473 }
474 
audit_set_backlog_wait_time(u32 timeout)475 static int audit_set_backlog_wait_time(u32 timeout)
476 {
477 	return audit_do_config_change("audit_backlog_wait_time",
478 				      &audit_backlog_wait_time, timeout);
479 }
480 
audit_set_enabled(u32 state)481 static int audit_set_enabled(u32 state)
482 {
483 	int rc;
484 	if (state > AUDIT_LOCKED)
485 		return -EINVAL;
486 
487 	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
488 	if (!rc)
489 		audit_ever_enabled |= !!state;
490 
491 	return rc;
492 }
493 
audit_set_failure(u32 state)494 static int audit_set_failure(u32 state)
495 {
496 	if (state != AUDIT_FAIL_SILENT
497 	    && state != AUDIT_FAIL_PRINTK
498 	    && state != AUDIT_FAIL_PANIC)
499 		return -EINVAL;
500 
501 	return audit_do_config_change("audit_failure", &audit_failure, state);
502 }
503 
504 /**
505  * auditd_conn_free - RCU helper to release an auditd connection struct
506  * @rcu: RCU head
507  *
508  * Description:
509  * Drop any references inside the auditd connection tracking struct and free
510  * the memory.
511  */
auditd_conn_free(struct rcu_head * rcu)512 static void auditd_conn_free(struct rcu_head *rcu)
513 {
514 	struct auditd_connection *ac;
515 
516 	ac = container_of(rcu, struct auditd_connection, rcu);
517 	put_pid(ac->pid);
518 	put_net(ac->net);
519 	kfree(ac);
520 }
521 
522 /**
523  * auditd_set - Set/Reset the auditd connection state
524  * @pid: auditd PID
525  * @portid: auditd netlink portid
526  * @net: auditd network namespace pointer
527  * @skb: the netlink command from the audit daemon
528  * @ack: netlink ack flag, cleared if ack'd here
529  *
530  * Description:
531  * This function will obtain and drop network namespace references as
532  * necessary.  Returns zero on success, negative values on failure.
533  */
auditd_set(struct pid * pid,u32 portid,struct net * net,struct sk_buff * skb,bool * ack)534 static int auditd_set(struct pid *pid, u32 portid, struct net *net,
535 		      struct sk_buff *skb, bool *ack)
536 {
537 	unsigned long flags;
538 	struct auditd_connection *ac_old, *ac_new;
539 	struct nlmsghdr *nlh;
540 
541 	if (!pid || !net)
542 		return -EINVAL;
543 
544 	ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
545 	if (!ac_new)
546 		return -ENOMEM;
547 	ac_new->pid = get_pid(pid);
548 	ac_new->portid = portid;
549 	ac_new->net = get_net(net);
550 
551 	/* send the ack now to avoid a race with the queue backlog */
552 	if (*ack) {
553 		nlh = nlmsg_hdr(skb);
554 		netlink_ack(skb, nlh, 0, NULL);
555 		*ack = false;
556 	}
557 
558 	spin_lock_irqsave(&auditd_conn_lock, flags);
559 	ac_old = rcu_dereference_protected(auditd_conn,
560 					   lockdep_is_held(&auditd_conn_lock));
561 	rcu_assign_pointer(auditd_conn, ac_new);
562 	spin_unlock_irqrestore(&auditd_conn_lock, flags);
563 
564 	if (ac_old)
565 		call_rcu(&ac_old->rcu, auditd_conn_free);
566 
567 	return 0;
568 }
569 
570 /**
571  * kauditd_printk_skb - Print the audit record to the ring buffer
572  * @skb: audit record
573  *
574  * Whatever the reason, this packet may not make it to the auditd connection
575  * so write it via printk so the information isn't completely lost.
576  */
kauditd_printk_skb(struct sk_buff * skb)577 static void kauditd_printk_skb(struct sk_buff *skb)
578 {
579 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
580 	char *data = nlmsg_data(nlh);
581 
582 	if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
583 		pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
584 }
585 
586 /**
587  * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
588  * @skb: audit record
589  * @error: error code (unused)
590  *
591  * Description:
592  * This should only be used by the kauditd_thread when it fails to flush the
593  * hold queue.
594  */
kauditd_rehold_skb(struct sk_buff * skb,__always_unused int error)595 static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error)
596 {
597 	/* put the record back in the queue */
598 	skb_queue_tail(&audit_hold_queue, skb);
599 }
600 
601 /**
602  * kauditd_hold_skb - Queue an audit record, waiting for auditd
603  * @skb: audit record
604  * @error: error code
605  *
606  * Description:
607  * Queue the audit record, waiting for an instance of auditd.  When this
608  * function is called we haven't given up yet on sending the record, but things
609  * are not looking good.  The first thing we want to do is try to write the
610  * record via printk and then see if we want to try and hold on to the record
611  * and queue it, if we have room.  If we want to hold on to the record, but we
612  * don't have room, record a record lost message.
613  */
kauditd_hold_skb(struct sk_buff * skb,int error)614 static void kauditd_hold_skb(struct sk_buff *skb, int error)
615 {
616 	/* at this point it is uncertain if we will ever send this to auditd so
617 	 * try to send the message via printk before we go any further */
618 	kauditd_printk_skb(skb);
619 
620 	/* can we just silently drop the message? */
621 	if (!audit_default)
622 		goto drop;
623 
624 	/* the hold queue is only for when the daemon goes away completely,
625 	 * not -EAGAIN failures; if we are in a -EAGAIN state requeue the
626 	 * record on the retry queue unless it's full, in which case drop it
627 	 */
628 	if (error == -EAGAIN) {
629 		if (!audit_backlog_limit ||
630 		    skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
631 			skb_queue_tail(&audit_retry_queue, skb);
632 			return;
633 		}
634 		audit_log_lost("kauditd retry queue overflow");
635 		goto drop;
636 	}
637 
638 	/* if we have room in the hold queue, queue the message */
639 	if (!audit_backlog_limit ||
640 	    skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
641 		skb_queue_tail(&audit_hold_queue, skb);
642 		return;
643 	}
644 
645 	/* we have no other options - drop the message */
646 	audit_log_lost("kauditd hold queue overflow");
647 drop:
648 	kfree_skb(skb);
649 }
650 
651 /**
652  * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
653  * @skb: audit record
654  * @error: error code (unused)
655  *
656  * Description:
657  * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
658  * but for some reason we are having problems sending it audit records so
659  * queue the given record and attempt to resend.
660  */
kauditd_retry_skb(struct sk_buff * skb,__always_unused int error)661 static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
662 {
663 	if (!audit_backlog_limit ||
664 	    skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
665 		skb_queue_tail(&audit_retry_queue, skb);
666 		return;
667 	}
668 
669 	/* we have to drop the record, send it via printk as a last effort */
670 	kauditd_printk_skb(skb);
671 	audit_log_lost("kauditd retry queue overflow");
672 	kfree_skb(skb);
673 }
674 
675 /**
676  * auditd_reset - Disconnect the auditd connection
677  * @ac: auditd connection state
678  *
679  * Description:
680  * Break the auditd/kauditd connection and move all the queued records into the
681  * hold queue in case auditd reconnects.  It is important to note that the @ac
682  * pointer should never be dereferenced inside this function as it may be NULL
683  * or invalid, you can only compare the memory address!  If @ac is NULL then
684  * the connection will always be reset.
685  */
auditd_reset(const struct auditd_connection * ac)686 static void auditd_reset(const struct auditd_connection *ac)
687 {
688 	unsigned long flags;
689 	struct sk_buff *skb;
690 	struct auditd_connection *ac_old;
691 
692 	/* if it isn't already broken, break the connection */
693 	spin_lock_irqsave(&auditd_conn_lock, flags);
694 	ac_old = rcu_dereference_protected(auditd_conn,
695 					   lockdep_is_held(&auditd_conn_lock));
696 	if (ac && ac != ac_old) {
697 		/* someone already registered a new auditd connection */
698 		spin_unlock_irqrestore(&auditd_conn_lock, flags);
699 		return;
700 	}
701 	rcu_assign_pointer(auditd_conn, NULL);
702 	spin_unlock_irqrestore(&auditd_conn_lock, flags);
703 
704 	if (ac_old)
705 		call_rcu(&ac_old->rcu, auditd_conn_free);
706 
707 	/* flush the retry queue to the hold queue, but don't touch the main
708 	 * queue since we need to process that normally for multicast */
709 	while ((skb = skb_dequeue(&audit_retry_queue)))
710 		kauditd_hold_skb(skb, -ECONNREFUSED);
711 }
712 
713 /**
714  * auditd_send_unicast_skb - Send a record via unicast to auditd
715  * @skb: audit record
716  *
717  * Description:
718  * Send a skb to the audit daemon, returns positive/zero values on success and
719  * negative values on failure; in all cases the skb will be consumed by this
720  * function.  If the send results in -ECONNREFUSED the connection with auditd
721  * will be reset.  This function may sleep so callers should not hold any locks
722  * where this would cause a problem.
723  */
auditd_send_unicast_skb(struct sk_buff * skb)724 static int auditd_send_unicast_skb(struct sk_buff *skb)
725 {
726 	int rc;
727 	u32 portid;
728 	struct net *net;
729 	struct sock *sk;
730 	struct auditd_connection *ac;
731 
732 	/* NOTE: we can't call netlink_unicast while in the RCU section so
733 	 *       take a reference to the network namespace and grab local
734 	 *       copies of the namespace, the sock, and the portid; the
735 	 *       namespace and sock aren't going to go away while we hold a
736 	 *       reference and if the portid does become invalid after the RCU
737 	 *       section netlink_unicast() should safely return an error */
738 
739 	rcu_read_lock();
740 	ac = rcu_dereference(auditd_conn);
741 	if (!ac) {
742 		rcu_read_unlock();
743 		kfree_skb(skb);
744 		rc = -ECONNREFUSED;
745 		goto err;
746 	}
747 	net = get_net(ac->net);
748 	sk = audit_get_sk(net);
749 	portid = ac->portid;
750 	rcu_read_unlock();
751 
752 	rc = netlink_unicast(sk, skb, portid, 0);
753 	put_net(net);
754 	if (rc < 0)
755 		goto err;
756 
757 	return rc;
758 
759 err:
760 	if (ac && rc == -ECONNREFUSED)
761 		auditd_reset(ac);
762 	return rc;
763 }
764 
765 /**
766  * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
767  * @sk: the sending sock
768  * @portid: the netlink destination
769  * @queue: the skb queue to process
770  * @retry_limit: limit on number of netlink unicast failures
771  * @skb_hook: per-skb hook for additional processing
772  * @err_hook: hook called if the skb fails the netlink unicast send
773  *
774  * Description:
775  * Run through the given queue and attempt to send the audit records to auditd,
776  * returns zero on success, negative values on failure.  It is up to the caller
777  * to ensure that the @sk is valid for the duration of this function.
778  *
779  */
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))780 static int kauditd_send_queue(struct sock *sk, u32 portid,
781 			      struct sk_buff_head *queue,
782 			      unsigned int retry_limit,
783 			      void (*skb_hook)(struct sk_buff *skb),
784 			      void (*err_hook)(struct sk_buff *skb, int error))
785 {
786 	int rc = 0;
787 	struct sk_buff *skb = NULL;
788 	struct sk_buff *skb_tail;
789 	unsigned int failed = 0;
790 
791 	/* NOTE: kauditd_thread takes care of all our locking, we just use
792 	 *       the netlink info passed to us (e.g. sk and portid) */
793 
794 	skb_tail = skb_peek_tail(queue);
795 	while ((skb != skb_tail) && (skb = skb_dequeue(queue))) {
796 		/* call the skb_hook for each skb we touch */
797 		if (skb_hook)
798 			(*skb_hook)(skb);
799 
800 		/* can we send to anyone via unicast? */
801 		if (!sk) {
802 			if (err_hook)
803 				(*err_hook)(skb, -ECONNREFUSED);
804 			continue;
805 		}
806 
807 retry:
808 		/* grab an extra skb reference in case of error */
809 		skb_get(skb);
810 		rc = netlink_unicast(sk, skb, portid, 0);
811 		if (rc < 0) {
812 			/* send failed - try a few times unless fatal error */
813 			if (++failed >= retry_limit ||
814 			    rc == -ECONNREFUSED || rc == -EPERM) {
815 				sk = NULL;
816 				if (err_hook)
817 					(*err_hook)(skb, rc);
818 				if (rc == -EAGAIN)
819 					rc = 0;
820 				/* continue to drain the queue */
821 				continue;
822 			} else
823 				goto retry;
824 		} else {
825 			/* skb sent - drop the extra reference and continue */
826 			consume_skb(skb);
827 			failed = 0;
828 		}
829 	}
830 
831 	return (rc >= 0 ? 0 : rc);
832 }
833 
834 /*
835  * kauditd_send_multicast_skb - Send a record to any multicast listeners
836  * @skb: audit record
837  *
838  * Description:
839  * Write a multicast message to anyone listening in the initial network
840  * namespace.  This function doesn't consume an skb as might be expected since
841  * it has to copy it anyways.
842  */
kauditd_send_multicast_skb(struct sk_buff * skb)843 static void kauditd_send_multicast_skb(struct sk_buff *skb)
844 {
845 	struct sk_buff *copy;
846 	struct sock *sock = audit_get_sk(&init_net);
847 	struct nlmsghdr *nlh;
848 
849 	/* NOTE: we are not taking an additional reference for init_net since
850 	 *       we don't have to worry about it going away */
851 
852 	if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
853 		return;
854 
855 	/*
856 	 * The seemingly wasteful skb_copy() rather than bumping the refcount
857 	 * using skb_get() is necessary because non-standard mods are made to
858 	 * the skb by the original kaudit unicast socket send routine.  The
859 	 * existing auditd daemon assumes this breakage.  Fixing this would
860 	 * require co-ordinating a change in the established protocol between
861 	 * the kaudit kernel subsystem and the auditd userspace code.  There is
862 	 * no reason for new multicast clients to continue with this
863 	 * non-compliance.
864 	 */
865 	copy = skb_copy(skb, GFP_KERNEL);
866 	if (!copy)
867 		return;
868 	nlh = nlmsg_hdr(copy);
869 	nlh->nlmsg_len = skb->len;
870 
871 	nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
872 }
873 
874 /**
875  * kauditd_thread - Worker thread to send audit records to userspace
876  * @dummy: unused
877  */
kauditd_thread(void * dummy)878 static int kauditd_thread(void *dummy)
879 {
880 	int rc;
881 	u32 portid = 0;
882 	struct net *net = NULL;
883 	struct sock *sk = NULL;
884 	struct auditd_connection *ac;
885 
886 #define UNICAST_RETRIES 5
887 
888 	set_freezable();
889 	while (!kthread_should_stop()) {
890 		/* NOTE: see the lock comments in auditd_send_unicast_skb() */
891 		rcu_read_lock();
892 		ac = rcu_dereference(auditd_conn);
893 		if (!ac) {
894 			rcu_read_unlock();
895 			goto main_queue;
896 		}
897 		net = get_net(ac->net);
898 		sk = audit_get_sk(net);
899 		portid = ac->portid;
900 		rcu_read_unlock();
901 
902 		/* attempt to flush the hold queue */
903 		rc = kauditd_send_queue(sk, portid,
904 					&audit_hold_queue, UNICAST_RETRIES,
905 					NULL, kauditd_rehold_skb);
906 		if (rc < 0) {
907 			sk = NULL;
908 			auditd_reset(ac);
909 			goto main_queue;
910 		}
911 
912 		/* attempt to flush the retry queue */
913 		rc = kauditd_send_queue(sk, portid,
914 					&audit_retry_queue, UNICAST_RETRIES,
915 					NULL, kauditd_hold_skb);
916 		if (rc < 0) {
917 			sk = NULL;
918 			auditd_reset(ac);
919 			goto main_queue;
920 		}
921 
922 main_queue:
923 		/* process the main queue - do the multicast send and attempt
924 		 * unicast, dump failed record sends to the retry queue; if
925 		 * sk == NULL due to previous failures we will just do the
926 		 * multicast send and move the record to the hold queue */
927 		rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
928 					kauditd_send_multicast_skb,
929 					(sk ?
930 					 kauditd_retry_skb : kauditd_hold_skb));
931 		if (ac && rc < 0)
932 			auditd_reset(ac);
933 		sk = NULL;
934 
935 		/* drop our netns reference, no auditd sends past this line */
936 		if (net) {
937 			put_net(net);
938 			net = NULL;
939 		}
940 
941 		/* we have processed all the queues so wake everyone */
942 		wake_up(&audit_backlog_wait);
943 
944 		/* NOTE: we want to wake up if there is anything on the queue,
945 		 *       regardless of if an auditd is connected, as we need to
946 		 *       do the multicast send and rotate records from the
947 		 *       main queue to the retry/hold queues */
948 		wait_event_freezable(kauditd_wait,
949 				     (skb_queue_len(&audit_queue) ? 1 : 0));
950 	}
951 
952 	return 0;
953 }
954 
audit_send_list_thread(void * _dest)955 int audit_send_list_thread(void *_dest)
956 {
957 	struct audit_netlink_list *dest = _dest;
958 	struct sk_buff *skb;
959 	struct sock *sk = audit_get_sk(dest->net);
960 
961 	/* wait for parent to finish and send an ACK */
962 	audit_ctl_lock();
963 	audit_ctl_unlock();
964 
965 	while ((skb = __skb_dequeue(&dest->q)) != NULL)
966 		netlink_unicast(sk, skb, dest->portid, 0);
967 
968 	put_net(dest->net);
969 	kfree(dest);
970 
971 	return 0;
972 }
973 
audit_make_reply(int seq,int type,int done,int multi,const void * payload,int size)974 struct sk_buff *audit_make_reply(int seq, int type, int done,
975 				 int multi, const void *payload, int size)
976 {
977 	struct sk_buff	*skb;
978 	struct nlmsghdr	*nlh;
979 	void		*data;
980 	int		flags = multi ? NLM_F_MULTI : 0;
981 	int		t     = done  ? NLMSG_DONE  : type;
982 
983 	skb = nlmsg_new(size, GFP_KERNEL);
984 	if (!skb)
985 		return NULL;
986 
987 	nlh	= nlmsg_put(skb, 0, seq, t, size, flags);
988 	if (!nlh)
989 		goto out_kfree_skb;
990 	data = nlmsg_data(nlh);
991 	memcpy(data, payload, size);
992 	return skb;
993 
994 out_kfree_skb:
995 	kfree_skb(skb);
996 	return NULL;
997 }
998 
audit_free_reply(struct audit_reply * reply)999 static void audit_free_reply(struct audit_reply *reply)
1000 {
1001 	if (!reply)
1002 		return;
1003 
1004 	kfree_skb(reply->skb);
1005 	if (reply->net)
1006 		put_net(reply->net);
1007 	kfree(reply);
1008 }
1009 
audit_send_reply_thread(void * arg)1010 static int audit_send_reply_thread(void *arg)
1011 {
1012 	struct audit_reply *reply = (struct audit_reply *)arg;
1013 
1014 	audit_ctl_lock();
1015 	audit_ctl_unlock();
1016 
1017 	/* Ignore failure. It'll only happen if the sender goes away,
1018 	   because our timeout is set to infinite. */
1019 	netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
1020 	reply->skb = NULL;
1021 	audit_free_reply(reply);
1022 	return 0;
1023 }
1024 
1025 /**
1026  * audit_send_reply - send an audit reply message via netlink
1027  * @request_skb: skb of request we are replying to (used to target the reply)
1028  * @seq: sequence number
1029  * @type: audit message type
1030  * @done: done (last) flag
1031  * @multi: multi-part message flag
1032  * @payload: payload data
1033  * @size: payload size
1034  *
1035  * Allocates a skb, builds the netlink message, and sends it to the port id.
1036  */
audit_send_reply(struct sk_buff * request_skb,int seq,int type,int done,int multi,const void * payload,int size)1037 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
1038 			     int multi, const void *payload, int size)
1039 {
1040 	struct task_struct *tsk;
1041 	struct audit_reply *reply;
1042 
1043 	reply = kzalloc(sizeof(*reply), GFP_KERNEL);
1044 	if (!reply)
1045 		return;
1046 
1047 	reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
1048 	if (!reply->skb)
1049 		goto err;
1050 	reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
1051 	reply->portid = NETLINK_CB(request_skb).portid;
1052 
1053 	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
1054 	if (IS_ERR(tsk))
1055 		goto err;
1056 
1057 	return;
1058 
1059 err:
1060 	audit_free_reply(reply);
1061 }
1062 
1063 /*
1064  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
1065  * control messages.
1066  */
audit_netlink_ok(struct sk_buff * skb,u16 msg_type)1067 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1068 {
1069 	int err = 0;
1070 
1071 	/* Only support initial user namespace for now. */
1072 	/*
1073 	 * We return ECONNREFUSED because it tricks userspace into thinking
1074 	 * that audit was not configured into the kernel.  Lots of users
1075 	 * configure their PAM stack (because that's what the distro does)
1076 	 * to reject login if unable to send messages to audit.  If we return
1077 	 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1078 	 * configured in and will let login proceed.  If we return EPERM
1079 	 * userspace will reject all logins.  This should be removed when we
1080 	 * support non init namespaces!!
1081 	 */
1082 	if (current_user_ns() != &init_user_ns)
1083 		return -ECONNREFUSED;
1084 
1085 	switch (msg_type) {
1086 	case AUDIT_LIST:
1087 	case AUDIT_ADD:
1088 	case AUDIT_DEL:
1089 		return -EOPNOTSUPP;
1090 	case AUDIT_GET:
1091 	case AUDIT_SET:
1092 	case AUDIT_GET_FEATURE:
1093 	case AUDIT_SET_FEATURE:
1094 	case AUDIT_LIST_RULES:
1095 	case AUDIT_ADD_RULE:
1096 	case AUDIT_DEL_RULE:
1097 	case AUDIT_SIGNAL_INFO:
1098 	case AUDIT_TTY_GET:
1099 	case AUDIT_TTY_SET:
1100 	case AUDIT_TRIM:
1101 	case AUDIT_MAKE_EQUIV:
1102 		/* Only support auditd and auditctl in initial pid namespace
1103 		 * for now. */
1104 		if (task_active_pid_ns(current) != &init_pid_ns)
1105 			return -EPERM;
1106 
1107 		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1108 			err = -EPERM;
1109 		break;
1110 	case AUDIT_USER:
1111 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1112 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1113 		if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1114 			err = -EPERM;
1115 		break;
1116 	default:  /* bad msg */
1117 		err = -EINVAL;
1118 	}
1119 
1120 	return err;
1121 }
1122 
audit_log_common_recv_msg(struct audit_context * context,struct audit_buffer ** ab,u16 msg_type)1123 static void audit_log_common_recv_msg(struct audit_context *context,
1124 					struct audit_buffer **ab, u16 msg_type)
1125 {
1126 	uid_t uid = from_kuid(&init_user_ns, current_uid());
1127 	pid_t pid = task_tgid_nr(current);
1128 
1129 	if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1130 		*ab = NULL;
1131 		return;
1132 	}
1133 
1134 	*ab = audit_log_start(context, GFP_KERNEL, msg_type);
1135 	if (unlikely(!*ab))
1136 		return;
1137 	audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1138 	audit_log_session_info(*ab);
1139 	audit_log_task_context(*ab);
1140 }
1141 
audit_log_user_recv_msg(struct audit_buffer ** ab,u16 msg_type)1142 static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1143 					   u16 msg_type)
1144 {
1145 	audit_log_common_recv_msg(NULL, ab, msg_type);
1146 }
1147 
is_audit_feature_set(int i)1148 static int is_audit_feature_set(int i)
1149 {
1150 	return af.features & AUDIT_FEATURE_TO_MASK(i);
1151 }
1152 
audit_get_feature(struct sk_buff * skb)1153 static int audit_get_feature(struct sk_buff *skb)
1154 {
1155 	u32 seq;
1156 
1157 	seq = nlmsg_hdr(skb)->nlmsg_seq;
1158 
1159 	audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1160 
1161 	return 0;
1162 }
1163 
audit_log_feature_change(int which,u32 old_feature,u32 new_feature,u32 old_lock,u32 new_lock,int res)1164 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1165 				     u32 old_lock, u32 new_lock, int res)
1166 {
1167 	struct audit_buffer *ab;
1168 
1169 	if (audit_enabled == AUDIT_OFF)
1170 		return;
1171 
1172 	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1173 	if (!ab)
1174 		return;
1175 	audit_log_task_info(ab);
1176 	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1177 			 audit_feature_names[which], !!old_feature, !!new_feature,
1178 			 !!old_lock, !!new_lock, res);
1179 	audit_log_end(ab);
1180 }
1181 
audit_set_feature(struct audit_features * uaf)1182 static int audit_set_feature(struct audit_features *uaf)
1183 {
1184 	int i;
1185 
1186 	BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1187 
1188 	/* if there is ever a version 2 we should handle that here */
1189 
1190 	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1191 		u32 feature = AUDIT_FEATURE_TO_MASK(i);
1192 		u32 old_feature, new_feature, old_lock, new_lock;
1193 
1194 		/* if we are not changing this feature, move along */
1195 		if (!(feature & uaf->mask))
1196 			continue;
1197 
1198 		old_feature = af.features & feature;
1199 		new_feature = uaf->features & feature;
1200 		new_lock = (uaf->lock | af.lock) & feature;
1201 		old_lock = af.lock & feature;
1202 
1203 		/* are we changing a locked feature? */
1204 		if (old_lock && (new_feature != old_feature)) {
1205 			audit_log_feature_change(i, old_feature, new_feature,
1206 						 old_lock, new_lock, 0);
1207 			return -EPERM;
1208 		}
1209 	}
1210 	/* nothing invalid, do the changes */
1211 	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1212 		u32 feature = AUDIT_FEATURE_TO_MASK(i);
1213 		u32 old_feature, new_feature, old_lock, new_lock;
1214 
1215 		/* if we are not changing this feature, move along */
1216 		if (!(feature & uaf->mask))
1217 			continue;
1218 
1219 		old_feature = af.features & feature;
1220 		new_feature = uaf->features & feature;
1221 		old_lock = af.lock & feature;
1222 		new_lock = (uaf->lock | af.lock) & feature;
1223 
1224 		if (new_feature != old_feature)
1225 			audit_log_feature_change(i, old_feature, new_feature,
1226 						 old_lock, new_lock, 1);
1227 
1228 		if (new_feature)
1229 			af.features |= feature;
1230 		else
1231 			af.features &= ~feature;
1232 		af.lock |= new_lock;
1233 	}
1234 
1235 	return 0;
1236 }
1237 
audit_replace(struct pid * pid)1238 static int audit_replace(struct pid *pid)
1239 {
1240 	pid_t pvnr;
1241 	struct sk_buff *skb;
1242 
1243 	pvnr = pid_vnr(pid);
1244 	skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1245 	if (!skb)
1246 		return -ENOMEM;
1247 	return auditd_send_unicast_skb(skb);
1248 }
1249 
audit_receive_msg(struct sk_buff * skb,struct nlmsghdr * nlh,bool * ack)1250 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
1251 			     bool *ack)
1252 {
1253 	u32			seq;
1254 	void			*data;
1255 	int			data_len;
1256 	int			err;
1257 	struct audit_buffer	*ab;
1258 	u16			msg_type = nlh->nlmsg_type;
1259 	struct audit_sig_info   *sig_data;
1260 	struct lsm_context	lsmctx = { NULL, 0, 0 };
1261 
1262 	err = audit_netlink_ok(skb, msg_type);
1263 	if (err)
1264 		return err;
1265 
1266 	seq  = nlh->nlmsg_seq;
1267 	data = nlmsg_data(nlh);
1268 	data_len = nlmsg_len(nlh);
1269 
1270 	switch (msg_type) {
1271 	case AUDIT_GET: {
1272 		struct audit_status	s;
1273 		memset(&s, 0, sizeof(s));
1274 		s.enabled		   = audit_enabled;
1275 		s.failure		   = audit_failure;
1276 		/* NOTE: use pid_vnr() so the PID is relative to the current
1277 		 *       namespace */
1278 		s.pid			   = auditd_pid_vnr();
1279 		s.rate_limit		   = audit_rate_limit;
1280 		s.backlog_limit		   = audit_backlog_limit;
1281 		s.lost			   = atomic_read(&audit_lost);
1282 		s.backlog		   = skb_queue_len(&audit_queue);
1283 		s.feature_bitmap	   = AUDIT_FEATURE_BITMAP_ALL;
1284 		s.backlog_wait_time	   = audit_backlog_wait_time;
1285 		s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1286 		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1287 		break;
1288 	}
1289 	case AUDIT_SET: {
1290 		struct audit_status	s;
1291 		memset(&s, 0, sizeof(s));
1292 		/* guard against past and future API changes */
1293 		memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1294 		if (s.mask & AUDIT_STATUS_ENABLED) {
1295 			err = audit_set_enabled(s.enabled);
1296 			if (err < 0)
1297 				return err;
1298 		}
1299 		if (s.mask & AUDIT_STATUS_FAILURE) {
1300 			err = audit_set_failure(s.failure);
1301 			if (err < 0)
1302 				return err;
1303 		}
1304 		if (s.mask & AUDIT_STATUS_PID) {
1305 			/* NOTE: we are using the vnr PID functions below
1306 			 *       because the s.pid value is relative to the
1307 			 *       namespace of the caller; at present this
1308 			 *       doesn't matter much since you can really only
1309 			 *       run auditd from the initial pid namespace, but
1310 			 *       something to keep in mind if this changes */
1311 			pid_t new_pid = s.pid;
1312 			pid_t auditd_pid;
1313 			struct pid *req_pid = task_tgid(current);
1314 
1315 			/* Sanity check - PID values must match. Setting
1316 			 * pid to 0 is how auditd ends auditing. */
1317 			if (new_pid && (new_pid != pid_vnr(req_pid)))
1318 				return -EINVAL;
1319 
1320 			/* test the auditd connection */
1321 			audit_replace(req_pid);
1322 
1323 			auditd_pid = auditd_pid_vnr();
1324 			if (auditd_pid) {
1325 				/* replacing a healthy auditd is not allowed */
1326 				if (new_pid) {
1327 					audit_log_config_change("audit_pid",
1328 							new_pid, auditd_pid, 0);
1329 					return -EEXIST;
1330 				}
1331 				/* only current auditd can unregister itself */
1332 				if (pid_vnr(req_pid) != auditd_pid) {
1333 					audit_log_config_change("audit_pid",
1334 							new_pid, auditd_pid, 0);
1335 					return -EACCES;
1336 				}
1337 			}
1338 
1339 			if (new_pid) {
1340 				/* register a new auditd connection */
1341 				err = auditd_set(req_pid,
1342 						 NETLINK_CB(skb).portid,
1343 						 sock_net(NETLINK_CB(skb).sk),
1344 						 skb, ack);
1345 				if (audit_enabled != AUDIT_OFF)
1346 					audit_log_config_change("audit_pid",
1347 								new_pid,
1348 								auditd_pid,
1349 								err ? 0 : 1);
1350 				if (err)
1351 					return err;
1352 
1353 				/* try to process any backlog */
1354 				wake_up_interruptible(&kauditd_wait);
1355 			} else {
1356 				if (audit_enabled != AUDIT_OFF)
1357 					audit_log_config_change("audit_pid",
1358 								new_pid,
1359 								auditd_pid, 1);
1360 
1361 				/* unregister the auditd connection */
1362 				auditd_reset(NULL);
1363 			}
1364 		}
1365 		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1366 			err = audit_set_rate_limit(s.rate_limit);
1367 			if (err < 0)
1368 				return err;
1369 		}
1370 		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1371 			err = audit_set_backlog_limit(s.backlog_limit);
1372 			if (err < 0)
1373 				return err;
1374 		}
1375 		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1376 			if (sizeof(s) > (size_t)nlh->nlmsg_len)
1377 				return -EINVAL;
1378 			if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1379 				return -EINVAL;
1380 			err = audit_set_backlog_wait_time(s.backlog_wait_time);
1381 			if (err < 0)
1382 				return err;
1383 		}
1384 		if (s.mask == AUDIT_STATUS_LOST) {
1385 			u32 lost = atomic_xchg(&audit_lost, 0);
1386 
1387 			audit_log_config_change("lost", 0, lost, 1);
1388 			return lost;
1389 		}
1390 		if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1391 			u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1392 
1393 			audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1394 			return actual;
1395 		}
1396 		break;
1397 	}
1398 	case AUDIT_GET_FEATURE:
1399 		err = audit_get_feature(skb);
1400 		if (err)
1401 			return err;
1402 		break;
1403 	case AUDIT_SET_FEATURE:
1404 		if (data_len < sizeof(struct audit_features))
1405 			return -EINVAL;
1406 		err = audit_set_feature(data);
1407 		if (err)
1408 			return err;
1409 		break;
1410 	case AUDIT_USER:
1411 	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1412 	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1413 		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1414 			return 0;
1415 		/* exit early if there isn't at least one character to print */
1416 		if (data_len < 2)
1417 			return -EINVAL;
1418 
1419 		err = audit_filter(msg_type, AUDIT_FILTER_USER);
1420 		if (err == 1) { /* match or error */
1421 			char *str = data;
1422 
1423 			err = 0;
1424 			if (msg_type == AUDIT_USER_TTY) {
1425 				err = tty_audit_push();
1426 				if (err)
1427 					break;
1428 			}
1429 			audit_log_user_recv_msg(&ab, msg_type);
1430 			if (msg_type != AUDIT_USER_TTY) {
1431 				/* ensure NULL termination */
1432 				str[data_len - 1] = '\0';
1433 				audit_log_format(ab, " msg='%.*s'",
1434 						 AUDIT_MESSAGE_TEXT_MAX,
1435 						 str);
1436 			} else {
1437 				audit_log_format(ab, " data=");
1438 				if (str[data_len - 1] == '\0')
1439 					data_len--;
1440 				audit_log_n_untrustedstring(ab, str, data_len);
1441 			}
1442 			audit_log_end(ab);
1443 		}
1444 		break;
1445 	case AUDIT_ADD_RULE:
1446 	case AUDIT_DEL_RULE:
1447 		if (data_len < sizeof(struct audit_rule_data))
1448 			return -EINVAL;
1449 		if (audit_enabled == AUDIT_LOCKED) {
1450 			audit_log_common_recv_msg(audit_context(), &ab,
1451 						  AUDIT_CONFIG_CHANGE);
1452 			audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1453 					 msg_type == AUDIT_ADD_RULE ?
1454 						"add_rule" : "remove_rule",
1455 					 audit_enabled);
1456 			audit_log_end(ab);
1457 			return -EPERM;
1458 		}
1459 		err = audit_rule_change(msg_type, seq, data, data_len);
1460 		break;
1461 	case AUDIT_LIST_RULES:
1462 		err = audit_list_rules_send(skb, seq);
1463 		break;
1464 	case AUDIT_TRIM:
1465 		audit_trim_trees();
1466 		audit_log_common_recv_msg(audit_context(), &ab,
1467 					  AUDIT_CONFIG_CHANGE);
1468 		audit_log_format(ab, " op=trim res=1");
1469 		audit_log_end(ab);
1470 		break;
1471 	case AUDIT_MAKE_EQUIV: {
1472 		void *bufp = data;
1473 		u32 sizes[2];
1474 		size_t msglen = data_len;
1475 		char *old, *new;
1476 
1477 		err = -EINVAL;
1478 		if (msglen < 2 * sizeof(u32))
1479 			break;
1480 		memcpy(sizes, bufp, 2 * sizeof(u32));
1481 		bufp += 2 * sizeof(u32);
1482 		msglen -= 2 * sizeof(u32);
1483 		old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1484 		if (IS_ERR(old)) {
1485 			err = PTR_ERR(old);
1486 			break;
1487 		}
1488 		new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1489 		if (IS_ERR(new)) {
1490 			err = PTR_ERR(new);
1491 			kfree(old);
1492 			break;
1493 		}
1494 		/* OK, here comes... */
1495 		err = audit_tag_tree(old, new);
1496 
1497 		audit_log_common_recv_msg(audit_context(), &ab,
1498 					  AUDIT_CONFIG_CHANGE);
1499 		audit_log_format(ab, " op=make_equiv old=");
1500 		audit_log_untrustedstring(ab, old);
1501 		audit_log_format(ab, " new=");
1502 		audit_log_untrustedstring(ab, new);
1503 		audit_log_format(ab, " res=%d", !err);
1504 		audit_log_end(ab);
1505 		kfree(old);
1506 		kfree(new);
1507 		break;
1508 	}
1509 	case AUDIT_SIGNAL_INFO:
1510 		if (lsmprop_is_set(&audit_sig_lsm)) {
1511 			err = security_lsmprop_to_secctx(&audit_sig_lsm,
1512 							 &lsmctx, LSM_ID_UNDEF);
1513 			if (err < 0)
1514 				return err;
1515 		}
1516 		sig_data = kmalloc(struct_size(sig_data, ctx, lsmctx.len),
1517 				   GFP_KERNEL);
1518 		if (!sig_data) {
1519 			if (lsmprop_is_set(&audit_sig_lsm))
1520 				security_release_secctx(&lsmctx);
1521 			return -ENOMEM;
1522 		}
1523 		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1524 		sig_data->pid = audit_sig_pid;
1525 		if (lsmprop_is_set(&audit_sig_lsm)) {
1526 			memcpy(sig_data->ctx, lsmctx.context, lsmctx.len);
1527 			security_release_secctx(&lsmctx);
1528 		}
1529 		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1530 				 sig_data, struct_size(sig_data, ctx,
1531 						       lsmctx.len));
1532 		kfree(sig_data);
1533 		break;
1534 	case AUDIT_TTY_GET: {
1535 		struct audit_tty_status s;
1536 		unsigned int t;
1537 
1538 		t = READ_ONCE(current->signal->audit_tty);
1539 		s.enabled = t & AUDIT_TTY_ENABLE;
1540 		s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1541 
1542 		audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1543 		break;
1544 	}
1545 	case AUDIT_TTY_SET: {
1546 		struct audit_tty_status s, old;
1547 		struct audit_buffer	*ab;
1548 		unsigned int t;
1549 
1550 		memset(&s, 0, sizeof(s));
1551 		/* guard against past and future API changes */
1552 		memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1553 		/* check if new data is valid */
1554 		if ((s.enabled != 0 && s.enabled != 1) ||
1555 		    (s.log_passwd != 0 && s.log_passwd != 1))
1556 			err = -EINVAL;
1557 
1558 		if (err)
1559 			t = READ_ONCE(current->signal->audit_tty);
1560 		else {
1561 			t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1562 			t = xchg(&current->signal->audit_tty, t);
1563 		}
1564 		old.enabled = t & AUDIT_TTY_ENABLE;
1565 		old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1566 
1567 		audit_log_common_recv_msg(audit_context(), &ab,
1568 					  AUDIT_CONFIG_CHANGE);
1569 		audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1570 				 " old-log_passwd=%d new-log_passwd=%d res=%d",
1571 				 old.enabled, s.enabled, old.log_passwd,
1572 				 s.log_passwd, !err);
1573 		audit_log_end(ab);
1574 		break;
1575 	}
1576 	default:
1577 		err = -EINVAL;
1578 		break;
1579 	}
1580 
1581 	return err < 0 ? err : 0;
1582 }
1583 
1584 /**
1585  * audit_receive - receive messages from a netlink control socket
1586  * @skb: the message buffer
1587  *
1588  * Parse the provided skb and deal with any messages that may be present,
1589  * malformed skbs are discarded.
1590  */
audit_receive(struct sk_buff * skb)1591 static void audit_receive(struct sk_buff *skb)
1592 {
1593 	struct nlmsghdr *nlh;
1594 	bool ack;
1595 	/*
1596 	 * len MUST be signed for nlmsg_next to be able to dec it below 0
1597 	 * if the nlmsg_len was not aligned
1598 	 */
1599 	int len;
1600 	int err;
1601 
1602 	nlh = nlmsg_hdr(skb);
1603 	len = skb->len;
1604 
1605 	audit_ctl_lock();
1606 	while (nlmsg_ok(nlh, len)) {
1607 		ack = nlh->nlmsg_flags & NLM_F_ACK;
1608 		err = audit_receive_msg(skb, nlh, &ack);
1609 
1610 		/* send an ack if the user asked for one and audit_receive_msg
1611 		 * didn't already do it, or if there was an error. */
1612 		if (ack || err)
1613 			netlink_ack(skb, nlh, err, NULL);
1614 
1615 		nlh = nlmsg_next(nlh, &len);
1616 	}
1617 	audit_ctl_unlock();
1618 
1619 	/* can't block with the ctrl lock, so penalize the sender now */
1620 	if (audit_backlog_limit &&
1621 	    (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1622 		DECLARE_WAITQUEUE(wait, current);
1623 
1624 		/* wake kauditd to try and flush the queue */
1625 		wake_up_interruptible(&kauditd_wait);
1626 
1627 		add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1628 		set_current_state(TASK_UNINTERRUPTIBLE);
1629 		schedule_timeout(audit_backlog_wait_time);
1630 		remove_wait_queue(&audit_backlog_wait, &wait);
1631 	}
1632 }
1633 
1634 /* Log information about who is connecting to the audit multicast socket */
audit_log_multicast(int group,const char * op,int err)1635 static void audit_log_multicast(int group, const char *op, int err)
1636 {
1637 	const struct cred *cred;
1638 	struct tty_struct *tty;
1639 	char comm[sizeof(current->comm)];
1640 	struct audit_buffer *ab;
1641 
1642 	if (!audit_enabled)
1643 		return;
1644 
1645 	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1646 	if (!ab)
1647 		return;
1648 
1649 	cred = current_cred();
1650 	tty = audit_get_tty();
1651 	audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1652 			 task_tgid_nr(current),
1653 			 from_kuid(&init_user_ns, cred->uid),
1654 			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
1655 			 tty ? tty_name(tty) : "(none)",
1656 			 audit_get_sessionid(current));
1657 	audit_put_tty(tty);
1658 	audit_log_task_context(ab); /* subj= */
1659 	audit_log_format(ab, " comm=");
1660 	audit_log_untrustedstring(ab, get_task_comm(comm, current));
1661 	audit_log_d_path_exe(ab, current->mm); /* exe= */
1662 	audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1663 	audit_log_end(ab);
1664 }
1665 
1666 /* Run custom bind function on netlink socket group connect or bind requests. */
audit_multicast_bind(struct net * net,int group)1667 static int audit_multicast_bind(struct net *net, int group)
1668 {
1669 	int err = 0;
1670 
1671 	if (!capable(CAP_AUDIT_READ))
1672 		err = -EPERM;
1673 	audit_log_multicast(group, "connect", err);
1674 	return err;
1675 }
1676 
audit_multicast_unbind(struct net * net,int group)1677 static void audit_multicast_unbind(struct net *net, int group)
1678 {
1679 	audit_log_multicast(group, "disconnect", 0);
1680 }
1681 
audit_net_init(struct net * net)1682 static int __net_init audit_net_init(struct net *net)
1683 {
1684 	struct netlink_kernel_cfg cfg = {
1685 		.input	= audit_receive,
1686 		.bind	= audit_multicast_bind,
1687 		.unbind	= audit_multicast_unbind,
1688 		.flags	= NL_CFG_F_NONROOT_RECV,
1689 		.groups	= AUDIT_NLGRP_MAX,
1690 	};
1691 
1692 	struct audit_net *aunet = net_generic(net, audit_net_id);
1693 
1694 	aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1695 	if (aunet->sk == NULL) {
1696 		audit_panic("cannot initialize netlink socket in namespace");
1697 		return -ENOMEM;
1698 	}
1699 	/* limit the timeout in case auditd is blocked/stopped */
1700 	aunet->sk->sk_sndtimeo = HZ / 10;
1701 
1702 	return 0;
1703 }
1704 
audit_net_exit(struct net * net)1705 static void __net_exit audit_net_exit(struct net *net)
1706 {
1707 	struct audit_net *aunet = net_generic(net, audit_net_id);
1708 
1709 	/* NOTE: you would think that we would want to check the auditd
1710 	 * connection and potentially reset it here if it lives in this
1711 	 * namespace, but since the auditd connection tracking struct holds a
1712 	 * reference to this namespace (see auditd_set()) we are only ever
1713 	 * going to get here after that connection has been released */
1714 
1715 	netlink_kernel_release(aunet->sk);
1716 }
1717 
1718 static struct pernet_operations audit_net_ops __net_initdata = {
1719 	.init = audit_net_init,
1720 	.exit = audit_net_exit,
1721 	.id = &audit_net_id,
1722 	.size = sizeof(struct audit_net),
1723 };
1724 
1725 /* Initialize audit support at boot time. */
audit_init(void)1726 static int __init audit_init(void)
1727 {
1728 	int i;
1729 
1730 	if (audit_initialized == AUDIT_DISABLED)
1731 		return 0;
1732 
1733 	audit_buffer_cache = KMEM_CACHE(audit_buffer, SLAB_PANIC);
1734 
1735 	skb_queue_head_init(&audit_queue);
1736 	skb_queue_head_init(&audit_retry_queue);
1737 	skb_queue_head_init(&audit_hold_queue);
1738 
1739 	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1740 		INIT_LIST_HEAD(&audit_inode_hash[i]);
1741 
1742 	mutex_init(&audit_cmd_mutex.lock);
1743 	audit_cmd_mutex.owner = NULL;
1744 
1745 	pr_info("initializing netlink subsys (%s)\n",
1746 		str_enabled_disabled(audit_default));
1747 	register_pernet_subsys(&audit_net_ops);
1748 
1749 	audit_initialized = AUDIT_INITIALIZED;
1750 
1751 	kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1752 	if (IS_ERR(kauditd_task)) {
1753 		int err = PTR_ERR(kauditd_task);
1754 		panic("audit: failed to start the kauditd thread (%d)\n", err);
1755 	}
1756 
1757 	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1758 		"state=initialized audit_enabled=%u res=1",
1759 		 audit_enabled);
1760 
1761 	return 0;
1762 }
1763 postcore_initcall(audit_init);
1764 
1765 /*
1766  * Process kernel command-line parameter at boot time.
1767  * audit={0|off} or audit={1|on}.
1768  */
audit_enable(char * str)1769 static int __init audit_enable(char *str)
1770 {
1771 	if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1772 		audit_default = AUDIT_OFF;
1773 	else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1774 		audit_default = AUDIT_ON;
1775 	else {
1776 		pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1777 		audit_default = AUDIT_ON;
1778 	}
1779 
1780 	if (audit_default == AUDIT_OFF)
1781 		audit_initialized = AUDIT_DISABLED;
1782 	if (audit_set_enabled(audit_default))
1783 		pr_err("audit: error setting audit state (%d)\n",
1784 		       audit_default);
1785 
1786 	pr_info("%s\n", audit_default ?
1787 		"enabled (after initialization)" : "disabled (until reboot)");
1788 
1789 	return 1;
1790 }
1791 __setup("audit=", audit_enable);
1792 
1793 /* Process kernel command-line parameter at boot time.
1794  * audit_backlog_limit=<n> */
audit_backlog_limit_set(char * str)1795 static int __init audit_backlog_limit_set(char *str)
1796 {
1797 	u32 audit_backlog_limit_arg;
1798 
1799 	pr_info("audit_backlog_limit: ");
1800 	if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1801 		pr_cont("using default of %u, unable to parse %s\n",
1802 			audit_backlog_limit, str);
1803 		return 1;
1804 	}
1805 
1806 	audit_backlog_limit = audit_backlog_limit_arg;
1807 	pr_cont("%d\n", audit_backlog_limit);
1808 
1809 	return 1;
1810 }
1811 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1812 
audit_buffer_free(struct audit_buffer * ab)1813 static void audit_buffer_free(struct audit_buffer *ab)
1814 {
1815 	struct sk_buff *skb;
1816 
1817 	if (!ab)
1818 		return;
1819 
1820 	while ((skb = skb_dequeue(&ab->skb_list)))
1821 		kfree_skb(skb);
1822 	kmem_cache_free(audit_buffer_cache, ab);
1823 }
1824 
audit_buffer_alloc(struct audit_context * ctx,gfp_t gfp_mask,int type)1825 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1826 					       gfp_t gfp_mask, int type)
1827 {
1828 	struct audit_buffer *ab;
1829 
1830 	ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1831 	if (!ab)
1832 		return NULL;
1833 
1834 	skb_queue_head_init(&ab->skb_list);
1835 
1836 	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1837 	if (!ab->skb)
1838 		goto err;
1839 
1840 	skb_queue_tail(&ab->skb_list, ab->skb);
1841 
1842 	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1843 		goto err;
1844 
1845 	ab->ctx = ctx;
1846 	ab->gfp_mask = gfp_mask;
1847 
1848 	return ab;
1849 
1850 err:
1851 	audit_buffer_free(ab);
1852 	return NULL;
1853 }
1854 
1855 /**
1856  * audit_serial - compute a serial number for the audit record
1857  *
1858  * Compute a serial number for the audit record.  Audit records are
1859  * written to user-space as soon as they are generated, so a complete
1860  * audit record may be written in several pieces.  The timestamp of the
1861  * record and this serial number are used by the user-space tools to
1862  * determine which pieces belong to the same audit record.  The
1863  * (timestamp,serial) tuple is unique for each syscall and is live from
1864  * syscall entry to syscall exit.
1865  *
1866  * NOTE: Another possibility is to store the formatted records off the
1867  * audit context (for those records that have a context), and emit them
1868  * all at syscall exit.  However, this could delay the reporting of
1869  * significant errors until syscall exit (or never, if the system
1870  * halts).
1871  */
audit_serial(void)1872 unsigned int audit_serial(void)
1873 {
1874 	static atomic_t serial = ATOMIC_INIT(0);
1875 
1876 	return atomic_inc_return(&serial);
1877 }
1878 
audit_get_stamp(struct audit_context * ctx,struct audit_stamp * stamp)1879 static inline void audit_get_stamp(struct audit_context *ctx,
1880 				   struct audit_stamp *stamp)
1881 {
1882 	if (!ctx || !auditsc_get_stamp(ctx, stamp)) {
1883 		ktime_get_coarse_real_ts64(&stamp->ctime);
1884 		stamp->serial = audit_serial();
1885 	}
1886 }
1887 
1888 /**
1889  * audit_log_start - obtain an audit buffer
1890  * @ctx: audit_context (may be NULL)
1891  * @gfp_mask: type of allocation
1892  * @type: audit message type
1893  *
1894  * Returns audit_buffer pointer on success or NULL on error.
1895  *
1896  * Obtain an audit buffer.  This routine does locking to obtain the
1897  * audit buffer, but then no locking is required for calls to
1898  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1899  * syscall, then the syscall is marked as auditable and an audit record
1900  * will be written at syscall exit.  If there is no associated task, then
1901  * task context (ctx) should be NULL.
1902  */
audit_log_start(struct audit_context * ctx,gfp_t gfp_mask,int type)1903 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1904 				     int type)
1905 {
1906 	struct audit_buffer *ab;
1907 
1908 	if (audit_initialized != AUDIT_INITIALIZED)
1909 		return NULL;
1910 
1911 	if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1912 		return NULL;
1913 
1914 	/* NOTE: don't ever fail/sleep on these two conditions:
1915 	 * 1. auditd generated record - since we need auditd to drain the
1916 	 *    queue; also, when we are checking for auditd, compare PIDs using
1917 	 *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1918 	 *    using a PID anchored in the caller's namespace
1919 	 * 2. generator holding the audit_cmd_mutex - we don't want to block
1920 	 *    while holding the mutex, although we do penalize the sender
1921 	 *    later in audit_receive() when it is safe to block
1922 	 */
1923 	if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1924 		long stime = audit_backlog_wait_time;
1925 
1926 		while (audit_backlog_limit &&
1927 		       (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1928 			/* wake kauditd to try and flush the queue */
1929 			wake_up_interruptible(&kauditd_wait);
1930 
1931 			/* sleep if we are allowed and we haven't exhausted our
1932 			 * backlog wait limit */
1933 			if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1934 				long rtime = stime;
1935 
1936 				DECLARE_WAITQUEUE(wait, current);
1937 
1938 				add_wait_queue_exclusive(&audit_backlog_wait,
1939 							 &wait);
1940 				set_current_state(TASK_UNINTERRUPTIBLE);
1941 				stime = schedule_timeout(rtime);
1942 				atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1943 				remove_wait_queue(&audit_backlog_wait, &wait);
1944 			} else {
1945 				if (audit_rate_check() && printk_ratelimit())
1946 					pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1947 						skb_queue_len(&audit_queue),
1948 						audit_backlog_limit);
1949 				audit_log_lost("backlog limit exceeded");
1950 				return NULL;
1951 			}
1952 		}
1953 	}
1954 
1955 	ab = audit_buffer_alloc(ctx, gfp_mask, type);
1956 	if (!ab) {
1957 		audit_log_lost("out of memory in audit_log_start");
1958 		return NULL;
1959 	}
1960 
1961 	audit_get_stamp(ab->ctx, &ab->stamp);
1962 	/* cancel dummy context to enable supporting records */
1963 	if (ctx)
1964 		ctx->dummy = 0;
1965 	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1966 			 (unsigned long long)ab->stamp.ctime.tv_sec,
1967 			 ab->stamp.ctime.tv_nsec/1000000,
1968 			 ab->stamp.serial);
1969 
1970 	return ab;
1971 }
1972 
1973 /**
1974  * audit_expand - expand skb in the audit buffer
1975  * @ab: audit_buffer
1976  * @extra: space to add at tail of the skb
1977  *
1978  * Returns 0 (no space) on failed expansion, or available space if
1979  * successful.
1980  */
audit_expand(struct audit_buffer * ab,int extra)1981 static inline int audit_expand(struct audit_buffer *ab, int extra)
1982 {
1983 	struct sk_buff *skb = ab->skb;
1984 	int oldtail = skb_tailroom(skb);
1985 	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1986 	int newtail = skb_tailroom(skb);
1987 
1988 	if (ret < 0) {
1989 		audit_log_lost("out of memory in audit_expand");
1990 		return 0;
1991 	}
1992 
1993 	skb->truesize += newtail - oldtail;
1994 	return newtail;
1995 }
1996 
1997 /*
1998  * Format an audit message into the audit buffer.  If there isn't enough
1999  * room in the audit buffer, more room will be allocated and vsnprint
2000  * will be called a second time.  Currently, we assume that a printk
2001  * can't format message larger than 1024 bytes, so we don't either.
2002  */
2003 static __printf(2, 0)
audit_log_vformat(struct audit_buffer * ab,const char * fmt,va_list args)2004 void audit_log_vformat(struct audit_buffer *ab, const char *fmt, va_list args)
2005 {
2006 	int len, avail;
2007 	struct sk_buff *skb;
2008 	va_list args2;
2009 
2010 	if (!ab)
2011 		return;
2012 
2013 	BUG_ON(!ab->skb);
2014 	skb = ab->skb;
2015 	avail = skb_tailroom(skb);
2016 	if (avail == 0) {
2017 		avail = audit_expand(ab, AUDIT_BUFSIZ);
2018 		if (!avail)
2019 			goto out;
2020 	}
2021 	va_copy(args2, args);
2022 	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
2023 	if (len >= avail) {
2024 		/* The printk buffer is 1024 bytes long, so if we get
2025 		 * here and AUDIT_BUFSIZ is at least 1024, then we can
2026 		 * log everything that printk could have logged. */
2027 		avail = audit_expand(ab,
2028 			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
2029 		if (!avail)
2030 			goto out_va_end;
2031 		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
2032 	}
2033 	if (len > 0)
2034 		skb_put(skb, len);
2035 out_va_end:
2036 	va_end(args2);
2037 out:
2038 	return;
2039 }
2040 
2041 /**
2042  * audit_log_format - format a message into the audit buffer.
2043  * @ab: audit_buffer
2044  * @fmt: format string
2045  * @...: optional parameters matching @fmt string
2046  *
2047  * All the work is done in audit_log_vformat.
2048  */
audit_log_format(struct audit_buffer * ab,const char * fmt,...)2049 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
2050 {
2051 	va_list args;
2052 
2053 	if (!ab)
2054 		return;
2055 	va_start(args, fmt);
2056 	audit_log_vformat(ab, fmt, args);
2057 	va_end(args);
2058 }
2059 
2060 /**
2061  * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
2062  * @ab: the audit_buffer
2063  * @buf: buffer to convert to hex
2064  * @len: length of @buf to be converted
2065  *
2066  * No return value; failure to expand is silently ignored.
2067  *
2068  * This function will take the passed buf and convert it into a string of
2069  * ascii hex digits. The new string is placed onto the skb.
2070  */
audit_log_n_hex(struct audit_buffer * ab,const unsigned char * buf,size_t len)2071 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
2072 		size_t len)
2073 {
2074 	int i, avail, new_len;
2075 	unsigned char *ptr;
2076 	struct sk_buff *skb;
2077 
2078 	if (!ab)
2079 		return;
2080 
2081 	BUG_ON(!ab->skb);
2082 	skb = ab->skb;
2083 	avail = skb_tailroom(skb);
2084 	new_len = len<<1;
2085 	if (new_len >= avail) {
2086 		/* Round the buffer request up to the next multiple */
2087 		new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2088 		avail = audit_expand(ab, new_len);
2089 		if (!avail)
2090 			return;
2091 	}
2092 
2093 	ptr = skb_tail_pointer(skb);
2094 	for (i = 0; i < len; i++)
2095 		ptr = hex_byte_pack_upper(ptr, buf[i]);
2096 	*ptr = 0;
2097 	skb_put(skb, len << 1); /* new string is twice the old string */
2098 }
2099 
2100 /*
2101  * Format a string of no more than slen characters into the audit buffer,
2102  * enclosed in quote marks.
2103  */
audit_log_n_string(struct audit_buffer * ab,const char * string,size_t slen)2104 void audit_log_n_string(struct audit_buffer *ab, const char *string,
2105 			size_t slen)
2106 {
2107 	int avail, new_len;
2108 	unsigned char *ptr;
2109 	struct sk_buff *skb;
2110 
2111 	if (!ab)
2112 		return;
2113 
2114 	BUG_ON(!ab->skb);
2115 	skb = ab->skb;
2116 	avail = skb_tailroom(skb);
2117 	new_len = slen + 3;	/* enclosing quotes + null terminator */
2118 	if (new_len > avail) {
2119 		avail = audit_expand(ab, new_len);
2120 		if (!avail)
2121 			return;
2122 	}
2123 	ptr = skb_tail_pointer(skb);
2124 	*ptr++ = '"';
2125 	memcpy(ptr, string, slen);
2126 	ptr += slen;
2127 	*ptr++ = '"';
2128 	*ptr = 0;
2129 	skb_put(skb, slen + 2);	/* don't include null terminator */
2130 }
2131 
2132 /**
2133  * audit_string_contains_control - does a string need to be logged in hex
2134  * @string: string to be checked
2135  * @len: max length of the string to check
2136  */
audit_string_contains_control(const char * string,size_t len)2137 bool audit_string_contains_control(const char *string, size_t len)
2138 {
2139 	const unsigned char *p;
2140 	for (p = string; p < (const unsigned char *)string + len; p++) {
2141 		if (*p == '"' || *p < 0x21 || *p > 0x7e)
2142 			return true;
2143 	}
2144 	return false;
2145 }
2146 
2147 /**
2148  * audit_log_n_untrustedstring - log a string that may contain random characters
2149  * @ab: audit_buffer
2150  * @string: string to be logged
2151  * @len: length of string (not including trailing null)
2152  *
2153  * This code will escape a string that is passed to it if the string
2154  * contains a control character, unprintable character, double quote mark,
2155  * or a space. Unescaped strings will start and end with a double quote mark.
2156  * Strings that are escaped are printed in hex (2 digits per char).
2157  *
2158  * The caller specifies the number of characters in the string to log, which may
2159  * or may not be the entire string.
2160  */
audit_log_n_untrustedstring(struct audit_buffer * ab,const char * string,size_t len)2161 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2162 				 size_t len)
2163 {
2164 	if (audit_string_contains_control(string, len))
2165 		audit_log_n_hex(ab, string, len);
2166 	else
2167 		audit_log_n_string(ab, string, len);
2168 }
2169 
2170 /**
2171  * audit_log_untrustedstring - log a string that may contain random characters
2172  * @ab: audit_buffer
2173  * @string: string to be logged
2174  *
2175  * Same as audit_log_n_untrustedstring(), except that strlen is used to
2176  * determine string length.
2177  */
audit_log_untrustedstring(struct audit_buffer * ab,const char * string)2178 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2179 {
2180 	audit_log_n_untrustedstring(ab, string, strlen(string));
2181 }
2182 
2183 /* 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)2184 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2185 		      const struct path *path)
2186 {
2187 	char *p, *pathname;
2188 
2189 	if (prefix)
2190 		audit_log_format(ab, "%s", prefix);
2191 
2192 	/* We will allow 11 spaces for ' (deleted)' to be appended */
2193 	pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2194 	if (!pathname) {
2195 		audit_log_format(ab, "\"<no_memory>\"");
2196 		return;
2197 	}
2198 	p = d_path(path, pathname, PATH_MAX+11);
2199 	if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2200 		/* FIXME: can we save some information here? */
2201 		audit_log_format(ab, "\"<too_long>\"");
2202 	} else
2203 		audit_log_untrustedstring(ab, p);
2204 	kfree(pathname);
2205 }
2206 
audit_log_session_info(struct audit_buffer * ab)2207 void audit_log_session_info(struct audit_buffer *ab)
2208 {
2209 	unsigned int sessionid = audit_get_sessionid(current);
2210 	uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2211 
2212 	audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2213 }
2214 
audit_log_key(struct audit_buffer * ab,char * key)2215 void audit_log_key(struct audit_buffer *ab, char *key)
2216 {
2217 	audit_log_format(ab, " key=");
2218 	if (key)
2219 		audit_log_untrustedstring(ab, key);
2220 	else
2221 		audit_log_format(ab, "(null)");
2222 }
2223 
2224 /**
2225  * audit_buffer_aux_new - Add an aux record buffer to the skb list
2226  * @ab: audit_buffer
2227  * @type: message type
2228  *
2229  * Aux records are allocated and added to the skb list of
2230  * the "main" record. The ab->skb is reset to point to the
2231  * aux record on its creation. When the aux record in complete
2232  * ab->skb has to be reset to point to the "main" record.
2233  * This allows the audit_log_ functions to be ignorant of
2234  * which kind of record it is logging to. It also avoids adding
2235  * special data for aux records.
2236  *
2237  * On success ab->skb will point to the new aux record.
2238  * Returns 0 on success, -ENOMEM should allocation fail.
2239  */
audit_buffer_aux_new(struct audit_buffer * ab,int type)2240 static int audit_buffer_aux_new(struct audit_buffer *ab, int type)
2241 {
2242 	WARN_ON(ab->skb != skb_peek(&ab->skb_list));
2243 
2244 	ab->skb = nlmsg_new(AUDIT_BUFSIZ, ab->gfp_mask);
2245 	if (!ab->skb)
2246 		goto err;
2247 	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
2248 		goto err;
2249 	skb_queue_tail(&ab->skb_list, ab->skb);
2250 
2251 	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
2252 			 (unsigned long long)ab->stamp.ctime.tv_sec,
2253 			 ab->stamp.ctime.tv_nsec/1000000,
2254 			 ab->stamp.serial);
2255 
2256 	return 0;
2257 
2258 err:
2259 	kfree_skb(ab->skb);
2260 	ab->skb = skb_peek(&ab->skb_list);
2261 	return -ENOMEM;
2262 }
2263 
2264 /**
2265  * audit_buffer_aux_end - Switch back to the "main" record from an aux record
2266  * @ab: audit_buffer
2267  *
2268  * Restores the "main" audit record to ab->skb.
2269  */
audit_buffer_aux_end(struct audit_buffer * ab)2270 static void audit_buffer_aux_end(struct audit_buffer *ab)
2271 {
2272 	ab->skb = skb_peek(&ab->skb_list);
2273 }
2274 
2275 /**
2276  * audit_log_subj_ctx - Add LSM subject information
2277  * @ab: audit_buffer
2278  * @prop: LSM subject properties.
2279  *
2280  * Add a subj= field and, if necessary, a AUDIT_MAC_TASK_CONTEXTS record.
2281  */
audit_log_subj_ctx(struct audit_buffer * ab,struct lsm_prop * prop)2282 int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
2283 {
2284 	struct lsm_context ctx;
2285 	char *space = "";
2286 	int error;
2287 	int i;
2288 
2289 	security_current_getlsmprop_subj(prop);
2290 	if (!lsmprop_is_set(prop))
2291 		return 0;
2292 
2293 	if (audit_subj_secctx_cnt < 2) {
2294 		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
2295 		if (error < 0) {
2296 			if (error != -EINVAL)
2297 				goto error_path;
2298 			return 0;
2299 		}
2300 		audit_log_format(ab, " subj=%s", ctx.context);
2301 		security_release_secctx(&ctx);
2302 		return 0;
2303 	}
2304 	/* Multiple LSMs provide contexts. Include an aux record. */
2305 	audit_log_format(ab, " subj=?");
2306 	error = audit_buffer_aux_new(ab, AUDIT_MAC_TASK_CONTEXTS);
2307 	if (error)
2308 		goto error_path;
2309 
2310 	for (i = 0; i < audit_subj_secctx_cnt; i++) {
2311 		error = security_lsmprop_to_secctx(prop, &ctx,
2312 						   audit_subj_lsms[i]->id);
2313 		if (error < 0) {
2314 			/*
2315 			 * Don't print anything. An LSM like BPF could
2316 			 * claim to support contexts, but only do so under
2317 			 * certain conditions.
2318 			 */
2319 			if (error == -EOPNOTSUPP)
2320 				continue;
2321 			if (error != -EINVAL)
2322 				audit_panic("error in audit_log_subj_ctx");
2323 		} else {
2324 			audit_log_format(ab, "%ssubj_%s=%s", space,
2325 					 audit_subj_lsms[i]->name, ctx.context);
2326 			space = " ";
2327 			security_release_secctx(&ctx);
2328 		}
2329 	}
2330 	audit_buffer_aux_end(ab);
2331 	return 0;
2332 
2333 error_path:
2334 	audit_panic("error in audit_log_subj_ctx");
2335 	return error;
2336 }
2337 EXPORT_SYMBOL(audit_log_subj_ctx);
2338 
audit_log_task_context(struct audit_buffer * ab)2339 int audit_log_task_context(struct audit_buffer *ab)
2340 {
2341 	struct lsm_prop prop;
2342 
2343 	security_current_getlsmprop_subj(&prop);
2344 	return audit_log_subj_ctx(ab, &prop);
2345 }
2346 EXPORT_SYMBOL(audit_log_task_context);
2347 
audit_log_obj_ctx(struct audit_buffer * ab,struct lsm_prop * prop)2348 int audit_log_obj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
2349 {
2350 	int i;
2351 	int rc;
2352 	int error = 0;
2353 	char *space = "";
2354 	struct lsm_context ctx;
2355 
2356 	if (audit_obj_secctx_cnt < 2) {
2357 		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
2358 		if (error < 0) {
2359 			if (error != -EINVAL)
2360 				goto error_path;
2361 			return error;
2362 		}
2363 		audit_log_format(ab, " obj=%s", ctx.context);
2364 		security_release_secctx(&ctx);
2365 		return 0;
2366 	}
2367 	audit_log_format(ab, " obj=?");
2368 	error = audit_buffer_aux_new(ab, AUDIT_MAC_OBJ_CONTEXTS);
2369 	if (error)
2370 		goto error_path;
2371 
2372 	for (i = 0; i < audit_obj_secctx_cnt; i++) {
2373 		rc = security_lsmprop_to_secctx(prop, &ctx,
2374 						audit_obj_lsms[i]->id);
2375 		if (rc < 0) {
2376 			audit_log_format(ab, "%sobj_%s=?", space,
2377 					 audit_obj_lsms[i]->name);
2378 			if (rc != -EINVAL)
2379 				audit_panic("error in audit_log_obj_ctx");
2380 			error = rc;
2381 		} else {
2382 			audit_log_format(ab, "%sobj_%s=%s", space,
2383 					 audit_obj_lsms[i]->name, ctx.context);
2384 			security_release_secctx(&ctx);
2385 		}
2386 		space = " ";
2387 	}
2388 
2389 	audit_buffer_aux_end(ab);
2390 	return error;
2391 
2392 error_path:
2393 	audit_panic("error in audit_log_obj_ctx");
2394 	return error;
2395 }
2396 
audit_log_d_path_exe(struct audit_buffer * ab,struct mm_struct * mm)2397 void audit_log_d_path_exe(struct audit_buffer *ab,
2398 			  struct mm_struct *mm)
2399 {
2400 	struct file *exe_file;
2401 
2402 	if (!mm)
2403 		goto out_null;
2404 
2405 	exe_file = get_mm_exe_file(mm);
2406 	if (!exe_file)
2407 		goto out_null;
2408 
2409 	audit_log_d_path(ab, " exe=", &exe_file->f_path);
2410 	fput(exe_file);
2411 	return;
2412 out_null:
2413 	audit_log_format(ab, " exe=(null)");
2414 }
2415 
audit_get_tty(void)2416 struct tty_struct *audit_get_tty(void)
2417 {
2418 	struct tty_struct *tty = NULL;
2419 	unsigned long flags;
2420 
2421 	spin_lock_irqsave(&current->sighand->siglock, flags);
2422 	if (current->signal)
2423 		tty = tty_kref_get(current->signal->tty);
2424 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
2425 	return tty;
2426 }
2427 
audit_put_tty(struct tty_struct * tty)2428 void audit_put_tty(struct tty_struct *tty)
2429 {
2430 	tty_kref_put(tty);
2431 }
2432 
audit_log_task_info(struct audit_buffer * ab)2433 void audit_log_task_info(struct audit_buffer *ab)
2434 {
2435 	const struct cred *cred;
2436 	char comm[sizeof(current->comm)];
2437 	struct tty_struct *tty;
2438 
2439 	if (!ab)
2440 		return;
2441 
2442 	cred = current_cred();
2443 	tty = audit_get_tty();
2444 	audit_log_format(ab,
2445 			 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2446 			 " euid=%u suid=%u fsuid=%u"
2447 			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2448 			 task_ppid_nr(current),
2449 			 task_tgid_nr(current),
2450 			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
2451 			 from_kuid(&init_user_ns, cred->uid),
2452 			 from_kgid(&init_user_ns, cred->gid),
2453 			 from_kuid(&init_user_ns, cred->euid),
2454 			 from_kuid(&init_user_ns, cred->suid),
2455 			 from_kuid(&init_user_ns, cred->fsuid),
2456 			 from_kgid(&init_user_ns, cred->egid),
2457 			 from_kgid(&init_user_ns, cred->sgid),
2458 			 from_kgid(&init_user_ns, cred->fsgid),
2459 			 tty ? tty_name(tty) : "(none)",
2460 			 audit_get_sessionid(current));
2461 	audit_put_tty(tty);
2462 	audit_log_format(ab, " comm=");
2463 	audit_log_untrustedstring(ab, get_task_comm(comm, current));
2464 	audit_log_d_path_exe(ab, current->mm);
2465 	audit_log_task_context(ab);
2466 }
2467 EXPORT_SYMBOL(audit_log_task_info);
2468 
2469 /**
2470  * audit_log_path_denied - report a path restriction denial
2471  * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2472  * @operation: specific operation name
2473  */
audit_log_path_denied(int type,const char * operation)2474 void audit_log_path_denied(int type, const char *operation)
2475 {
2476 	struct audit_buffer *ab;
2477 
2478 	if (!audit_enabled)
2479 		return;
2480 
2481 	/* Generate log with subject, operation, outcome. */
2482 	ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2483 	if (!ab)
2484 		return;
2485 	audit_log_format(ab, "op=%s", operation);
2486 	audit_log_task_info(ab);
2487 	audit_log_format(ab, " res=0");
2488 	audit_log_end(ab);
2489 }
2490 
2491 /* global counter which is incremented every time something logs in */
2492 static atomic_t session_id = ATOMIC_INIT(0);
2493 
audit_set_loginuid_perm(kuid_t loginuid)2494 static int audit_set_loginuid_perm(kuid_t loginuid)
2495 {
2496 	/* if we are unset, we don't need privs */
2497 	if (!audit_loginuid_set(current))
2498 		return 0;
2499 	/* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2500 	if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2501 		return -EPERM;
2502 	/* it is set, you need permission */
2503 	if (!capable(CAP_AUDIT_CONTROL))
2504 		return -EPERM;
2505 	/* reject if this is not an unset and we don't allow that */
2506 	if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2507 				 && uid_valid(loginuid))
2508 		return -EPERM;
2509 	return 0;
2510 }
2511 
audit_log_set_loginuid(kuid_t koldloginuid,kuid_t kloginuid,unsigned int oldsessionid,unsigned int sessionid,int rc)2512 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2513 				   unsigned int oldsessionid,
2514 				   unsigned int sessionid, int rc)
2515 {
2516 	struct audit_buffer *ab;
2517 	uid_t uid, oldloginuid, loginuid;
2518 	struct tty_struct *tty;
2519 
2520 	if (!audit_enabled)
2521 		return;
2522 
2523 	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2524 	if (!ab)
2525 		return;
2526 
2527 	uid = from_kuid(&init_user_ns, task_uid(current));
2528 	oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2529 	loginuid = from_kuid(&init_user_ns, kloginuid);
2530 	tty = audit_get_tty();
2531 
2532 	audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2533 	audit_log_task_context(ab);
2534 	audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2535 			 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2536 			 oldsessionid, sessionid, !rc);
2537 	audit_put_tty(tty);
2538 	audit_log_end(ab);
2539 }
2540 
2541 /**
2542  * audit_set_loginuid - set current task's loginuid
2543  * @loginuid: loginuid value
2544  *
2545  * Returns 0.
2546  *
2547  * Called (set) from fs/proc/base.c::proc_loginuid_write().
2548  */
audit_set_loginuid(kuid_t loginuid)2549 int audit_set_loginuid(kuid_t loginuid)
2550 {
2551 	unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2552 	kuid_t oldloginuid;
2553 	int rc;
2554 
2555 	oldloginuid = audit_get_loginuid(current);
2556 	oldsessionid = audit_get_sessionid(current);
2557 
2558 	rc = audit_set_loginuid_perm(loginuid);
2559 	if (rc)
2560 		goto out;
2561 
2562 	/* are we setting or clearing? */
2563 	if (uid_valid(loginuid)) {
2564 		sessionid = (unsigned int)atomic_inc_return(&session_id);
2565 		if (unlikely(sessionid == AUDIT_SID_UNSET))
2566 			sessionid = (unsigned int)atomic_inc_return(&session_id);
2567 	}
2568 
2569 	current->sessionid = sessionid;
2570 	current->loginuid = loginuid;
2571 out:
2572 	audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2573 	return rc;
2574 }
2575 
2576 /**
2577  * audit_signal_info - record signal info for shutting down audit subsystem
2578  * @sig: signal value
2579  * @t: task being signaled
2580  *
2581  * If the audit subsystem is being terminated, record the task (pid)
2582  * and uid that is doing that.
2583  */
audit_signal_info(int sig,struct task_struct * t)2584 int audit_signal_info(int sig, struct task_struct *t)
2585 {
2586 	kuid_t uid = current_uid(), auid;
2587 
2588 	if (auditd_test_task(t) &&
2589 	    (sig == SIGTERM || sig == SIGHUP ||
2590 	     sig == SIGUSR1 || sig == SIGUSR2)) {
2591 		audit_sig_pid = task_tgid_nr(current);
2592 		auid = audit_get_loginuid(current);
2593 		if (uid_valid(auid))
2594 			audit_sig_uid = auid;
2595 		else
2596 			audit_sig_uid = uid;
2597 		security_current_getlsmprop_subj(&audit_sig_lsm);
2598 	}
2599 
2600 	return audit_signal_info_syscall(t);
2601 }
2602 
2603 /**
2604  * __audit_log_end - enqueue one audit record
2605  * @skb: the buffer to send
2606  */
__audit_log_end(struct sk_buff * skb)2607 static void __audit_log_end(struct sk_buff *skb)
2608 {
2609 	struct nlmsghdr *nlh;
2610 
2611 	if (audit_rate_check()) {
2612 		/* setup the netlink header, see the comments in
2613 		 * kauditd_send_multicast_skb() for length quirks */
2614 		nlh = nlmsg_hdr(skb);
2615 		nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2616 
2617 		/* queue the netlink packet */
2618 		skb_queue_tail(&audit_queue, skb);
2619 	} else {
2620 		audit_log_lost("rate limit exceeded");
2621 		kfree_skb(skb);
2622 	}
2623 }
2624 
2625 /**
2626  * audit_log_end - end one audit record
2627  * @ab: the audit_buffer
2628  *
2629  * We can not do a netlink send inside an irq context because it blocks (last
2630  * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2631  * queue and a kthread is scheduled to remove them from the queue outside the
2632  * irq context.  May be called in any context.
2633  */
audit_log_end(struct audit_buffer * ab)2634 void audit_log_end(struct audit_buffer *ab)
2635 {
2636 	struct sk_buff *skb;
2637 
2638 	if (!ab)
2639 		return;
2640 
2641 	while ((skb = skb_dequeue(&ab->skb_list)))
2642 		__audit_log_end(skb);
2643 
2644 	/* poke the kauditd thread */
2645 	wake_up_interruptible(&kauditd_wait);
2646 
2647 	audit_buffer_free(ab);
2648 }
2649 
2650 /**
2651  * audit_log - Log an audit record
2652  * @ctx: audit context
2653  * @gfp_mask: type of allocation
2654  * @type: audit message type
2655  * @fmt: format string to use
2656  * @...: variable parameters matching the format string
2657  *
2658  * This is a convenience function that calls audit_log_start,
2659  * audit_log_vformat, and audit_log_end.  It may be called
2660  * in any context.
2661  */
audit_log(struct audit_context * ctx,gfp_t gfp_mask,int type,const char * fmt,...)2662 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2663 	       const char *fmt, ...)
2664 {
2665 	struct audit_buffer *ab;
2666 	va_list args;
2667 
2668 	ab = audit_log_start(ctx, gfp_mask, type);
2669 	if (ab) {
2670 		va_start(args, fmt);
2671 		audit_log_vformat(ab, fmt, args);
2672 		va_end(args);
2673 		audit_log_end(ab);
2674 	}
2675 }
2676 
2677 EXPORT_SYMBOL(audit_log_start);
2678 EXPORT_SYMBOL(audit_log_end);
2679 EXPORT_SYMBOL(audit_log_format);
2680 EXPORT_SYMBOL(audit_log);
2681