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