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	*/
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	*/
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	*/
241	void audit_ctl_unlock(void)
242	{
243	audit_cmd_mutex.owner = NULL;
244	mutex_unlock(lock: &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	*/
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	*/
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(pid: 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	*/
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, id: audit_net_id);
297	return aunet->sk;
298	}
299
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(fmt: "audit: %s\n", message);
311	break;
312	}
313	}
314
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: &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	*/
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(v: &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: &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
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(ctx: audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
390	if (unlikely(!ab))
391	return rc;
392	audit_log_format(ab, fmt: "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, fmt: " res=%d", allow_changes);
398	audit_log_end(ab);
399	return rc;
400	}
401
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
428	static int audit_set_rate_limit(u32 limit)
429	{
430	return audit_do_config_change(function_name: "audit_rate_limit", to_change: &audit_rate_limit, new: limit);
431	}
432
433	static int audit_set_backlog_limit(u32 limit)
434	{
435	return audit_do_config_change(function_name: "audit_backlog_limit", to_change: &audit_backlog_limit, new: limit);
436	}
437
438	static int audit_set_backlog_wait_time(u32 timeout)
439	{
440	return audit_do_config_change(function_name: "audit_backlog_wait_time",
441	to_change: &audit_backlog_wait_time, new: timeout);
442	}
443
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(function_name: "audit_enabled", to_change: &audit_enabled, new: state);
451	if (!rc)
452	audit_ever_enabled |= !!state;
453
454	return rc;
455	}
456
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(function_name: "audit_failure", to_change: &audit_failure, new: 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	*/
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(pid: ac->pid);
481	put_net(net: ac->net);
482	kfree(objp: 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	*/
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(in_skb: skb, nlh, err: 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(lock: &auditd_conn_lock, flags);
526
527	if (ac_old)
528	call_rcu(head: &ac_old->rcu, func: 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	*/
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	*/
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(list: &audit_hold_queue, newsk: 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	*/
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(list_: &audit_retry_queue) < audit_backlog_limit) {
594	skb_queue_tail(list: &audit_retry_queue, newsk: skb);
595	return;
596	}
597	audit_log_lost(message: "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(list_: &audit_hold_queue) < audit_backlog_limit) {
604	skb_queue_tail(list: &audit_hold_queue, newsk: skb);
605	return;
606	}
607
608	/* we have no other options - drop the message */
609	audit_log_lost(message: "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	*/
624	static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
625	{
626	if (!audit_backlog_limit ||
627	skb_queue_len(list_: &audit_retry_queue) < audit_backlog_limit) {
628	skb_queue_tail(list: &audit_retry_queue, newsk: 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(message: "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	*/
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(lock: &auditd_conn_lock, flags);
662	return;
663	}
664	rcu_assign_pointer(auditd_conn, NULL);
665	spin_unlock_irqrestore(lock: &auditd_conn_lock, flags);
666
667	if (ac_old)
668	call_rcu(head: &ac_old->rcu, func: 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(list: &audit_retry_queue)))
673	kauditd_hold_skb(skb, error: -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	*/
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(net: ac->net);
711	sk = audit_get_sk(net);
712	portid = ac->portid;
713	rcu_read_unlock();
714
715	rc = netlink_unicast(ssk: sk, skb, portid, nonblock: 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	*/
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(list_: queue);
758	while ((skb != skb_tail) && (skb = skb_dequeue(list: 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(ssk: sk, skb, portid, nonblock: 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	*/
806	static void kauditd_send_multicast_skb(struct sk_buff *skb)
807	{
808	struct sk_buff *copy;
809	struct sock *sock = audit_get_sk(net: &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(sk: sock, group: 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(skb: copy);
832	nlh->nlmsg_len = skb->len;
833
834	nlmsg_multicast(sk: sock, skb: copy, portid: 0, group: AUDIT_NLGRP_READLOG, GFP_KERNEL);
835	}
836
837	/**
838	* kauditd_thread - Worker thread to send audit records to userspace
839	* @dummy: unused
840	*/
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(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	queue: &audit_hold_queue, UNICAST_RETRIES,
868	NULL, err_hook: 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	queue: &audit_retry_queue, UNICAST_RETRIES,
878	NULL, err_hook: 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, queue: &audit_queue, retry_limit: 1,
891	skb_hook: kauditd_send_multicast_skb,
892	err_hook: (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
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(net: 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(list: &dest->q)) != NULL)
929	netlink_unicast(ssk: sk, skb, portid: dest->portid, nonblock: 0);
930
931	put_net(net: dest->net);
932	kfree(objp: dest);
933
934	return 0;
935	}
936
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(payload: size, GFP_KERNEL);
947	if (!skb)
948	return NULL;
949
950	nlh = nlmsg_put(skb, portid: 0, seq, type: t, payload: 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
962	static void audit_free_reply(struct audit_reply *reply)
963	{
964	if (!reply)
965	return;
966
967	kfree_skb(skb: reply->skb);
968	if (reply->net)
969	put_net(net: reply->net);
970	kfree(objp: reply);
971	}
972
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(ssk: audit_get_sk(net: reply->net), skb: reply->skb, portid: reply->portid, nonblock: 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	*/
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(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(ptr: 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	*/
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
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(to: &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(ctx: context, GFP_KERNEL, type: msg_type);
1098	if (unlikely(!*ab))
1099	return;
1100	audit_log_format(ab: *ab, fmt: "pid=%d uid=%u ", pid, uid);
1101	audit_log_session_info(ab: *ab);
1102	audit_log_task_context(ab: *ab);
1103	}
1104
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
1111	static int is_audit_feature_set(int i)
1112	{
1113	return af.features & AUDIT_FEATURE_TO_MASK(i);
1114	}
1115
1116
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(request_skb: skb, seq, AUDIT_GET_FEATURE, done: 0, multi: 0, payload: &af, size: sizeof(af));
1124
1125	return 0;
1126	}
1127
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(ctx: audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1137	if (!ab)
1138	return;
1139	audit_log_task_info(ab);
1140	audit_log_format(ab, fmt: " 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
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(which: i, old_feature, new_feature,
1170	old_lock, new_lock, res: 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(which: i, old_feature, new_feature,
1190	old_lock, new_lock, res: 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
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(seq: 0, AUDIT_REPLACE, done: 0, multi: 0, payload: &pvnr, size: sizeof(pvnr));
1209	if (!skb)
1210	return -ENOMEM;
1211	return auditd_send_unicast_skb(skb);
1212	}
1213
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	struct lsm_context lsmctx = { NULL, 0, 0 };
1225
1226	err = audit_netlink_ok(skb, msg_type);
1227	if (err)
1228	return err;
1229
1230	seq = nlh->nlmsg_seq;
1231	data = nlmsg_data(nlh);
1232	data_len = nlmsg_len(nlh);
1233
1234	switch (msg_type) {
1235	case AUDIT_GET: {
1236	struct audit_status s;
1237	memset(&s, 0, sizeof(s));
1238	s.enabled = audit_enabled;
1239	s.failure = audit_failure;
1240	/* NOTE: use pid_vnr() so the PID is relative to the current
1241	* namespace */
1242	s.pid = auditd_pid_vnr();
1243	s.rate_limit = audit_rate_limit;
1244	s.backlog_limit = audit_backlog_limit;
1245	s.lost = atomic_read(v: &audit_lost);
1246	s.backlog = skb_queue_len(list_: &audit_queue);
1247	s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL;
1248	s.backlog_wait_time = audit_backlog_wait_time;
1249	s.backlog_wait_time_actual = atomic_read(v: &audit_backlog_wait_time_actual);
1250	audit_send_reply(request_skb: skb, seq, AUDIT_GET, done: 0, multi: 0, payload: &s, size: sizeof(s));
1251	break;
1252	}
1253	case AUDIT_SET: {
1254	struct audit_status s;
1255	memset(&s, 0, sizeof(s));
1256	/* guard against past and future API changes */
1257	memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1258	if (s.mask & AUDIT_STATUS_ENABLED) {
1259	err = audit_set_enabled(state: s.enabled);
1260	if (err < 0)
1261	return err;
1262	}
1263	if (s.mask & AUDIT_STATUS_FAILURE) {
1264	err = audit_set_failure(state: s.failure);
1265	if (err < 0)
1266	return err;
1267	}
1268	if (s.mask & AUDIT_STATUS_PID) {
1269	/* NOTE: we are using the vnr PID functions below
1270	* because the s.pid value is relative to the
1271	* namespace of the caller; at present this
1272	* doesn't matter much since you can really only
1273	* run auditd from the initial pid namespace, but
1274	* something to keep in mind if this changes */
1275	pid_t new_pid = s.pid;
1276	pid_t auditd_pid;
1277	struct pid *req_pid = task_tgid(current);
1278
1279	/* Sanity check - PID values must match. Setting
1280	* pid to 0 is how auditd ends auditing. */
1281	if (new_pid && (new_pid != pid_vnr(pid: req_pid)))
1282	return -EINVAL;
1283
1284	/* test the auditd connection */
1285	audit_replace(pid: req_pid);
1286
1287	auditd_pid = auditd_pid_vnr();
1288	if (auditd_pid) {
1289	/* replacing a healthy auditd is not allowed */
1290	if (new_pid) {
1291	audit_log_config_change(function_name: "audit_pid",
1292	new: new_pid, old: auditd_pid, allow_changes: 0);
1293	return -EEXIST;
1294	}
1295	/* only current auditd can unregister itself */
1296	if (pid_vnr(pid: req_pid) != auditd_pid) {
1297	audit_log_config_change(function_name: "audit_pid",
1298	new: new_pid, old: auditd_pid, allow_changes: 0);
1299	return -EACCES;
1300	}
1301	}
1302
1303	if (new_pid) {
1304	/* register a new auditd connection */
1305	err = auditd_set(pid: req_pid,
1306	NETLINK_CB(skb).portid,
1307	net: sock_net(NETLINK_CB(skb).sk),
1308	skb, ack);
1309	if (audit_enabled != AUDIT_OFF)
1310	audit_log_config_change(function_name: "audit_pid",
1311	new: new_pid,
1312	old: auditd_pid,
1313	allow_changes: err ? 0 : 1);
1314	if (err)
1315	return err;
1316
1317	/* try to process any backlog */
1318	wake_up_interruptible(&kauditd_wait);
1319	} else {
1320	if (audit_enabled != AUDIT_OFF)
1321	audit_log_config_change(function_name: "audit_pid",
1322	new: new_pid,
1323	old: auditd_pid, allow_changes: 1);
1324
1325	/* unregister the auditd connection */
1326	auditd_reset(NULL);
1327	}
1328	}
1329	if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1330	err = audit_set_rate_limit(limit: s.rate_limit);
1331	if (err < 0)
1332	return err;
1333	}
1334	if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1335	err = audit_set_backlog_limit(limit: s.backlog_limit);
1336	if (err < 0)
1337	return err;
1338	}
1339	if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1340	if (sizeof(s) > (size_t)nlh->nlmsg_len)
1341	return -EINVAL;
1342	if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1343	return -EINVAL;
1344	err = audit_set_backlog_wait_time(timeout: s.backlog_wait_time);
1345	if (err < 0)
1346	return err;
1347	}
1348	if (s.mask == AUDIT_STATUS_LOST) {
1349	u32 lost = atomic_xchg(v: &audit_lost, new: 0);
1350
1351	audit_log_config_change(function_name: "lost", new: 0, old: lost, allow_changes: 1);
1352	return lost;
1353	}
1354	if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1355	u32 actual = atomic_xchg(v: &audit_backlog_wait_time_actual, new: 0);
1356
1357	audit_log_config_change(function_name: "backlog_wait_time_actual", new: 0, old: actual, allow_changes: 1);
1358	return actual;
1359	}
1360	break;
1361	}
1362	case AUDIT_GET_FEATURE:
1363	err = audit_get_feature(skb);
1364	if (err)
1365	return err;
1366	break;
1367	case AUDIT_SET_FEATURE:
1368	if (data_len < sizeof(struct audit_features))
1369	return -EINVAL;
1370	err = audit_set_feature(uaf: data);
1371	if (err)
1372	return err;
1373	break;
1374	case AUDIT_USER:
1375	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1376	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1377	if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1378	return 0;
1379	/* exit early if there isn't at least one character to print */
1380	if (data_len < 2)
1381	return -EINVAL;
1382
1383	err = audit_filter(msgtype: msg_type, AUDIT_FILTER_USER);
1384	if (err == 1) { /* match or error */
1385	char *str = data;
1386
1387	err = 0;
1388	if (msg_type == AUDIT_USER_TTY) {
1389	err = tty_audit_push();
1390	if (err)
1391	break;
1392	}
1393	audit_log_user_recv_msg(ab: &ab, msg_type);
1394	if (msg_type != AUDIT_USER_TTY) {
1395	/* ensure NULL termination */
1396	str[data_len - 1] = '\0';
1397	audit_log_format(ab, fmt: " msg='%.*s'",
1398	AUDIT_MESSAGE_TEXT_MAX,
1399	str);
1400	} else {
1401	audit_log_format(ab, fmt: " data=");
1402	if (str[data_len - 1] == '\0')
1403	data_len--;
1404	audit_log_n_untrustedstring(ab, string: str, n: data_len);
1405	}
1406	audit_log_end(ab);
1407	}
1408	break;
1409	case AUDIT_ADD_RULE:
1410	case AUDIT_DEL_RULE:
1411	if (data_len < sizeof(struct audit_rule_data))
1412	return -EINVAL;
1413	if (audit_enabled == AUDIT_LOCKED) {
1414	audit_log_common_recv_msg(context: audit_context(), ab: &ab,
1415	AUDIT_CONFIG_CHANGE);
1416	audit_log_format(ab, fmt: " op=%s audit_enabled=%d res=0",
1417	msg_type == AUDIT_ADD_RULE ?
1418	"add_rule" : "remove_rule",
1419	audit_enabled);
1420	audit_log_end(ab);
1421	return -EPERM;
1422	}
1423	err = audit_rule_change(type: msg_type, seq, data, datasz: data_len);
1424	break;
1425	case AUDIT_LIST_RULES:
1426	err = audit_list_rules_send(request_skb: skb, seq);
1427	break;
1428	case AUDIT_TRIM:
1429	audit_trim_trees();
1430	audit_log_common_recv_msg(context: audit_context(), ab: &ab,
1431	AUDIT_CONFIG_CHANGE);
1432	audit_log_format(ab, fmt: " op=trim res=1");
1433	audit_log_end(ab);
1434	break;
1435	case AUDIT_MAKE_EQUIV: {
1436	void *bufp = data;
1437	u32 sizes[2];
1438	size_t msglen = data_len;
1439	char *old, *new;
1440
1441	err = -EINVAL;
1442	if (msglen < 2 * sizeof(u32))
1443	break;
1444	memcpy(sizes, bufp, 2 * sizeof(u32));
1445	bufp += 2 * sizeof(u32);
1446	msglen -= 2 * sizeof(u32);
1447	old = audit_unpack_string(bufp: &bufp, remain: &msglen, len: sizes[0]);
1448	if (IS_ERR(ptr: old)) {
1449	err = PTR_ERR(ptr: old);
1450	break;
1451	}
1452	new = audit_unpack_string(bufp: &bufp, remain: &msglen, len: sizes[1]);
1453	if (IS_ERR(ptr: new)) {
1454	err = PTR_ERR(ptr: new);
1455	kfree(objp: old);
1456	break;
1457	}
1458	/* OK, here comes... */
1459	err = audit_tag_tree(old, new);
1460
1461	audit_log_common_recv_msg(context: audit_context(), ab: &ab,
1462	AUDIT_CONFIG_CHANGE);
1463	audit_log_format(ab, fmt: " op=make_equiv old=");
1464	audit_log_untrustedstring(ab, string: old);
1465	audit_log_format(ab, fmt: " new=");
1466	audit_log_untrustedstring(ab, string: new);
1467	audit_log_format(ab, fmt: " res=%d", !err);
1468	audit_log_end(ab);
1469	kfree(objp: old);
1470	kfree(objp: new);
1471	break;
1472	}
1473	case AUDIT_SIGNAL_INFO:
1474	if (lsmprop_is_set(prop: &audit_sig_lsm)) {
1475	err = security_lsmprop_to_secctx(prop: &audit_sig_lsm,
1476	cp: &lsmctx);
1477	if (err < 0)
1478	return err;
1479	}
1480	sig_data = kmalloc(struct_size(sig_data, ctx, lsmctx.len),
1481	GFP_KERNEL);
1482	if (!sig_data) {
1483	if (lsmprop_is_set(prop: &audit_sig_lsm))
1484	security_release_secctx(cp: &lsmctx);
1485	return -ENOMEM;
1486	}
1487	sig_data->uid = from_kuid(to: &init_user_ns, uid: audit_sig_uid);
1488	sig_data->pid = audit_sig_pid;
1489	if (lsmprop_is_set(prop: &audit_sig_lsm)) {
1490	memcpy(sig_data->ctx, lsmctx.context, lsmctx.len);
1491	security_release_secctx(cp: &lsmctx);
1492	}
1493	audit_send_reply(request_skb: skb, seq, AUDIT_SIGNAL_INFO, done: 0, multi: 0,
1494	payload: sig_data, struct_size(sig_data, ctx,
1495	lsmctx.len));
1496	kfree(objp: 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(request_skb: skb, seq, AUDIT_TTY_GET, done: 0, multi: 0, payload: &s, size: 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(&current->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(context: audit_context(), ab: &ab,
1532	AUDIT_CONFIG_CHANGE);
1533	audit_log_format(ab, fmt: " 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	*/
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, remaining: len)) {
1571	ack = nlh->nlmsg_flags & NLM_F_ACK;
1572	err = audit_receive_msg(skb, nlh, ack: &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(in_skb: skb, nlh, err, NULL);
1578
1579	nlh = nlmsg_next(nlh, remaining: &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(list_: &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(wq_head: &audit_backlog_wait, wq_entry: &wait);
1592	set_current_state(TASK_UNINTERRUPTIBLE);
1593	schedule_timeout(timeout: audit_backlog_wait_time);
1594	remove_wait_queue(wq_head: &audit_backlog_wait, wq_entry: &wait);
1595	}
1596	}
1597
1598	/* Log information about who is connecting to the audit multicast socket */
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(ctx: 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, fmt: "pid=%u uid=%u auid=%u tty=%s ses=%u",
1616	task_tgid_nr(current),
1617	from_kuid(to: &init_user_ns, uid: cred->uid),
1618	from_kuid(to: &init_user_ns, uid: 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, fmt: " 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, fmt: " 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. */
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, op: "connect", err);
1638	return err;
1639	}
1640
1641	static void audit_multicast_unbind(struct net *net, int group)
1642	{
1643	audit_log_multicast(group, op: "disconnect", err: 0);
1644	}
1645
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, id: audit_net_id);
1657
1658	aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, cfg: &cfg);
1659	if (aunet->sk == NULL) {
1660	audit_panic(message: "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
1669	static void __net_exit audit_net_exit(struct net *net)
1670	{
1671	struct audit_net *aunet = net_generic(net, id: 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(sk: 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. */
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(list: &audit_queue);
1700	skb_queue_head_init(list: &audit_retry_queue);
1701	skb_queue_head_init(list: &audit_hold_queue);
1702
1703	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1704	INIT_LIST_HEAD(list: &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(ptr: kauditd_task)) {
1717	int err = PTR_ERR(ptr: kauditd_task);
1718	panic(fmt: "audit: failed to start the kauditd thread (%d)\n", err);
1719	}
1720
1721	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1722	fmt: "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	*/
1733	static int __init audit_enable(char *str)
1734	{
1735	if (!strcasecmp(s1: str, s2: "off") || !strcmp(str, "0"))
1736	audit_default = AUDIT_OFF;
1737	else if (!strcasecmp(s1: str, s2: "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(state: 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> */
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(s: str, base: 0, res: &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
1777	static void audit_buffer_free(struct audit_buffer *ab)
1778	{
1779	if (!ab)
1780	return;
1781
1782	kfree_skb(skb: ab->skb);
1783	kmem_cache_free(s: audit_buffer_cache, objp: ab);
1784	}
1785
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, flags: gfp_mask);
1796	if (!ab->skb)
1797	goto err;
1798	if (!nlmsg_put(skb: ab->skb, portid: 0, seq: 0, type, payload: 0, flags: 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	*/
1828	unsigned int audit_serial(void)
1829	{
1830	static atomic_t serial = ATOMIC_INIT(0);
1831
1832	return atomic_inc_return(v: &serial);
1833	}
1834
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(ts: 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	*/
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(list_: &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_flags: gfp_mask) && (stime > 0)) {
1892	long rtime = stime;
1893
1894	DECLARE_WAITQUEUE(wait, current);
1895
1896	add_wait_queue_exclusive(wq_head: &audit_backlog_wait,
1897	wq_entry: &wait);
1898	set_current_state(TASK_UNINTERRUPTIBLE);
1899	stime = schedule_timeout(timeout: rtime);
1900	atomic_add(i: rtime - stime, v: &audit_backlog_wait_time_actual);
1901	remove_wait_queue(wq_head: &audit_backlog_wait, wq_entry: &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(message: "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(message: "out of memory in audit_log_start");
1916	return NULL;
1917	}
1918
1919	audit_get_stamp(ctx: ab->ctx, t: &t, serial: &serial);
1920	/* cancel dummy context to enable supporting records */
1921	if (ctx)
1922	ctx->dummy = 0;
1923	audit_log_format(ab, fmt: "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	*/
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, nhead: 0, ntail: extra, gfp_mask: ab->gfp_mask);
1942	int newtail = skb_tailroom(skb);
1943
1944	if (ret < 0) {
1945	audit_log_lost(message: "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	*/
1959	static __printf(2, 0)
1960	void audit_log_vformat(struct audit_buffer *ab, const char *fmt, 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(buf: skb_tail_pointer(skb), size: 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(buf: skb_tail_pointer(skb), size: avail, fmt, args: 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	*/
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	*/
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, extra: 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(buf: ptr, byte: buf[i]);
2052	*ptr = 0;
2053	skb_put(skb, len: 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	*/
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, extra: 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, len: 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	*/
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	*/
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, buf: string, len);
2122	else
2123	audit_log_n_string(ab, string, slen: 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	*/
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 */
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, fmt: "%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, fmt: "\"<no_memory>\"");
2152	return;
2153	}
2154	p = d_path(path, pathname, PATH_MAX+11);
2155	if (IS_ERR(ptr: p)) { /* Should never happen since we send PATH_MAX */
2156	/* FIXME: can we save some information here? */
2157	audit_log_format(ab, fmt: "\"<too_long>\"");
2158	} else
2159	audit_log_untrustedstring(ab, string: p);
2160	kfree(objp: pathname);
2161	}
2162
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(to: &init_user_ns, uid: audit_get_loginuid(current));
2167
2168	audit_log_format(ab, fmt: "auid=%u ses=%u", auid, sessionid);
2169	}
2170
2171	void audit_log_key(struct audit_buffer *ab, char *key)
2172	{
2173	audit_log_format(ab, fmt: " key=");
2174	if (key)
2175	audit_log_untrustedstring(ab, string: key);
2176	else
2177	audit_log_format(ab, fmt: "(null)");
2178	}
2179
2180	int audit_log_task_context(struct audit_buffer *ab)
2181	{
2182	struct lsm_prop prop;
2183	struct lsm_context ctx;
2184	int error;
2185
2186	security_current_getlsmprop_subj(prop: &prop);
2187	if (!lsmprop_is_set(prop: &prop))
2188	return 0;
2189
2190	error = security_lsmprop_to_secctx(prop: &prop, cp: &ctx);
2191	if (error < 0) {
2192	if (error != -EINVAL)
2193	goto error_path;
2194	return 0;
2195	}
2196
2197	audit_log_format(ab, fmt: " subj=%s", ctx.context);
2198	security_release_secctx(cp: &ctx);
2199	return 0;
2200
2201	error_path:
2202	audit_panic(message: "error in audit_log_task_context");
2203	return error;
2204	}
2205	EXPORT_SYMBOL(audit_log_task_context);
2206
2207	void audit_log_d_path_exe(struct audit_buffer *ab,
2208	struct mm_struct *mm)
2209	{
2210	struct file *exe_file;
2211
2212	if (!mm)
2213	goto out_null;
2214
2215	exe_file = get_mm_exe_file(mm);
2216	if (!exe_file)
2217	goto out_null;
2218
2219	audit_log_d_path(ab, prefix: " exe=", path: &exe_file->f_path);
2220	fput(exe_file);
2221	return;
2222	out_null:
2223	audit_log_format(ab, fmt: " exe=(null)");
2224	}
2225
2226	struct tty_struct *audit_get_tty(void)
2227	{
2228	struct tty_struct *tty = NULL;
2229	unsigned long flags;
2230
2231	spin_lock_irqsave(&current->sighand->siglock, flags);
2232	if (current->signal)
2233	tty = tty_kref_get(current->signal->tty);
2234	spin_unlock_irqrestore(lock: &current->sighand->siglock, flags);
2235	return tty;
2236	}
2237
2238	void audit_put_tty(struct tty_struct *tty)
2239	{
2240	tty_kref_put(tty);
2241	}
2242
2243	void audit_log_task_info(struct audit_buffer *ab)
2244	{
2245	const struct cred *cred;
2246	char comm[sizeof(current->comm)];
2247	struct tty_struct *tty;
2248
2249	if (!ab)
2250	return;
2251
2252	cred = current_cred();
2253	tty = audit_get_tty();
2254	audit_log_format(ab,
2255	fmt: " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2256	" euid=%u suid=%u fsuid=%u"
2257	" egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2258	task_ppid_nr(current),
2259	task_tgid_nr(current),
2260	from_kuid(to: &init_user_ns, uid: audit_get_loginuid(current)),
2261	from_kuid(to: &init_user_ns, uid: cred->uid),
2262	from_kgid(to: &init_user_ns, gid: cred->gid),
2263	from_kuid(to: &init_user_ns, uid: cred->euid),
2264	from_kuid(to: &init_user_ns, uid: cred->suid),
2265	from_kuid(to: &init_user_ns, uid: cred->fsuid),
2266	from_kgid(to: &init_user_ns, gid: cred->egid),
2267	from_kgid(to: &init_user_ns, gid: cred->sgid),
2268	from_kgid(to: &init_user_ns, gid: cred->fsgid),
2269	tty ? tty_name(tty) : "(none)",
2270	audit_get_sessionid(current));
2271	audit_put_tty(tty);
2272	audit_log_format(ab, fmt: " comm=");
2273	audit_log_untrustedstring(ab, get_task_comm(comm, current));
2274	audit_log_d_path_exe(ab, current->mm);
2275	audit_log_task_context(ab);
2276	}
2277	EXPORT_SYMBOL(audit_log_task_info);
2278
2279	/**
2280	* audit_log_path_denied - report a path restriction denial
2281	* @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2282	* @operation: specific operation name
2283	*/
2284	void audit_log_path_denied(int type, const char *operation)
2285	{
2286	struct audit_buffer *ab;
2287
2288	if (!audit_enabled)
2289	return;
2290
2291	/* Generate log with subject, operation, outcome. */
2292	ab = audit_log_start(ctx: audit_context(), GFP_KERNEL, type);
2293	if (!ab)
2294	return;
2295	audit_log_format(ab, fmt: "op=%s", operation);
2296	audit_log_task_info(ab);
2297	audit_log_format(ab, fmt: " res=0");
2298	audit_log_end(ab);
2299	}
2300
2301	/* global counter which is incremented every time something logs in */
2302	static atomic_t session_id = ATOMIC_INIT(0);
2303
2304	static int audit_set_loginuid_perm(kuid_t loginuid)
2305	{
2306	/* if we are unset, we don't need privs */
2307	if (!audit_loginuid_set(current))
2308	return 0;
2309	/* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2310	if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2311	return -EPERM;
2312	/* it is set, you need permission */
2313	if (!capable(CAP_AUDIT_CONTROL))
2314	return -EPERM;
2315	/* reject if this is not an unset and we don't allow that */
2316	if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2317	&& uid_valid(uid: loginuid))
2318	return -EPERM;
2319	return 0;
2320	}
2321
2322	static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2323	unsigned int oldsessionid,
2324	unsigned int sessionid, int rc)
2325	{
2326	struct audit_buffer *ab;
2327	uid_t uid, oldloginuid, loginuid;
2328	struct tty_struct *tty;
2329
2330	if (!audit_enabled)
2331	return;
2332
2333	ab = audit_log_start(ctx: audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2334	if (!ab)
2335	return;
2336
2337	uid = from_kuid(to: &init_user_ns, task_uid(current));
2338	oldloginuid = from_kuid(to: &init_user_ns, uid: koldloginuid);
2339	loginuid = from_kuid(to: &init_user_ns, uid: kloginuid);
2340	tty = audit_get_tty();
2341
2342	audit_log_format(ab, fmt: "pid=%d uid=%u", task_tgid_nr(current), uid);
2343	audit_log_task_context(ab);
2344	audit_log_format(ab, fmt: " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2345	oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2346	oldsessionid, sessionid, !rc);
2347	audit_put_tty(tty);
2348	audit_log_end(ab);
2349	}
2350
2351	/**
2352	* audit_set_loginuid - set current task's loginuid
2353	* @loginuid: loginuid value
2354	*
2355	* Returns 0.
2356	*
2357	* Called (set) from fs/proc/base.c::proc_loginuid_write().
2358	*/
2359	int audit_set_loginuid(kuid_t loginuid)
2360	{
2361	unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2362	kuid_t oldloginuid;
2363	int rc;
2364
2365	oldloginuid = audit_get_loginuid(current);
2366	oldsessionid = audit_get_sessionid(current);
2367
2368	rc = audit_set_loginuid_perm(loginuid);
2369	if (rc)
2370	goto out;
2371
2372	/* are we setting or clearing? */
2373	if (uid_valid(uid: loginuid)) {
2374	sessionid = (unsigned int)atomic_inc_return(v: &session_id);
2375	if (unlikely(sessionid == AUDIT_SID_UNSET))
2376	sessionid = (unsigned int)atomic_inc_return(v: &session_id);
2377	}
2378
2379	current->sessionid = sessionid;
2380	current->loginuid = loginuid;
2381	out:
2382	audit_log_set_loginuid(koldloginuid: oldloginuid, kloginuid: loginuid, oldsessionid, sessionid, rc);
2383	return rc;
2384	}
2385
2386	/**
2387	* audit_signal_info - record signal info for shutting down audit subsystem
2388	* @sig: signal value
2389	* @t: task being signaled
2390	*
2391	* If the audit subsystem is being terminated, record the task (pid)
2392	* and uid that is doing that.
2393	*/
2394	int audit_signal_info(int sig, struct task_struct *t)
2395	{
2396	kuid_t uid = current_uid(), auid;
2397
2398	if (auditd_test_task(task: t) &&
2399	(sig == SIGTERM || sig == SIGHUP ||
2400	sig == SIGUSR1 || sig == SIGUSR2)) {
2401	audit_sig_pid = task_tgid_nr(current);
2402	auid = audit_get_loginuid(current);
2403	if (uid_valid(uid: auid))
2404	audit_sig_uid = auid;
2405	else
2406	audit_sig_uid = uid;
2407	security_current_getlsmprop_subj(prop: &audit_sig_lsm);
2408	}
2409
2410	return audit_signal_info_syscall(t);
2411	}
2412
2413	/**
2414	* audit_log_end - end one audit record
2415	* @ab: the audit_buffer
2416	*
2417	* We can not do a netlink send inside an irq context because it blocks (last
2418	* arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2419	* queue and a kthread is scheduled to remove them from the queue outside the
2420	* irq context. May be called in any context.
2421	*/
2422	void audit_log_end(struct audit_buffer *ab)
2423	{
2424	struct sk_buff *skb;
2425	struct nlmsghdr *nlh;
2426
2427	if (!ab)
2428	return;
2429
2430	if (audit_rate_check()) {
2431	skb = ab->skb;
2432	ab->skb = NULL;
2433
2434	/* setup the netlink header, see the comments in
2435	* kauditd_send_multicast_skb() for length quirks */
2436	nlh = nlmsg_hdr(skb);
2437	nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2438
2439	/* queue the netlink packet and poke the kauditd thread */
2440	skb_queue_tail(list: &audit_queue, newsk: skb);
2441	wake_up_interruptible(&kauditd_wait);
2442	} else
2443	audit_log_lost(message: "rate limit exceeded");
2444
2445	audit_buffer_free(ab);
2446	}
2447
2448	/**
2449	* audit_log - Log an audit record
2450	* @ctx: audit context
2451	* @gfp_mask: type of allocation
2452	* @type: audit message type
2453	* @fmt: format string to use
2454	* @...: variable parameters matching the format string
2455	*
2456	* This is a convenience function that calls audit_log_start,
2457	* audit_log_vformat, and audit_log_end. It may be called
2458	* in any context.
2459	*/
2460	void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2461	const char *fmt, ...)
2462	{
2463	struct audit_buffer *ab;
2464	va_list args;
2465
2466	ab = audit_log_start(ctx, gfp_mask, type);
2467	if (ab) {
2468	va_start(args, fmt);
2469	audit_log_vformat(ab, fmt, args);
2470	va_end(args);
2471	audit_log_end(ab);
2472	}
2473	}
2474
2475	EXPORT_SYMBOL(audit_log_start);
2476	EXPORT_SYMBOL(audit_log_end);
2477	EXPORT_SYMBOL(audit_log_format);
2478	EXPORT_SYMBOL(audit_log);
2479