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