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