audit.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* audit.c -- Auditing support
   3 * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
   4 * System-call specific features have moved to auditsc.c
   5 *
   6 * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
   7 * All Rights Reserved.
   8 *
   9 * Written by Rickard E. (Rik) Faith <faith@redhat.com>
  10 *
  11 * Goals: 1) Integrate fully with Security Modules.
  12 *	  2) Minimal run-time overhead:
  13 *	     a) Minimal when syscall auditing is disabled (audit_enable=0).
  14 *	     b) Small when syscall auditing is enabled and no audit record
  15 *		is generated (defer as much work as possible to record
  16 *		generation time):
  17 *		i) context is allocated,
  18 *		ii) names from getname are stored without a copy, and
  19 *		iii) inode information stored from path_lookup.
  20 *	  3) Ability to disable syscall auditing at boot time (audit=0).
  21 *	  4) Usable by other parts of the kernel (if audit_log* is called,
  22 *	     then a syscall record will be generated automatically for the
  23 *	     current syscall).
  24 *	  5) Netlink interface to user-space.
  25 *	  6) Support low-overhead kernel-based filtering to minimize the
  26 *	     information that must be passed to user-space.
  27 *
  28 * Audit userspace, documentation, tests, and bug/issue trackers:
  29 * 	https://github.com/linux-audit
  30 */
  31
  32#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  33
  34#include <linux/file.h>
  35#include <linux/init.h>
  36#include <linux/types.h>
  37#include <linux/atomic.h>
  38#include <linux/mm.h>
  39#include <linux/export.h>
  40#include <linux/slab.h>
  41#include <linux/err.h>
  42#include <linux/kthread.h>
  43#include <linux/kernel.h>
  44#include <linux/syscalls.h>
  45#include <linux/spinlock.h>
  46#include <linux/rcupdate.h>
  47#include <linux/mutex.h>
  48#include <linux/gfp.h>
  49#include <linux/pid.h>
  50
  51#include <linux/audit.h>
  52
  53#include <net/sock.h>
  54#include <net/netlink.h>
  55#include <linux/skbuff.h>
  56#include <linux/security.h>
  57#include <linux/lsm_hooks.h>
  58#include <linux/freezer.h>
  59#include <linux/pid_namespace.h>
  60#include <net/netns/generic.h>
  61
  62#include "audit.h"
  63
  64/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
  65 * (Initialization happens after skb_init is called.) */
  66#define AUDIT_DISABLED		-1
  67#define AUDIT_UNINITIALIZED	0
  68#define AUDIT_INITIALIZED	1
  69static int	audit_initialized = AUDIT_UNINITIALIZED;
  70
  71u32		audit_enabled = AUDIT_OFF;
  72bool		audit_ever_enabled = !!AUDIT_OFF;
  73
  74EXPORT_SYMBOL_GPL(audit_enabled);
  75
  76/* Default state when kernel boots without any parameters. */
  77static u32	audit_default = AUDIT_OFF;
  78
  79/* If auditing cannot proceed, audit_failure selects what happens. */
  80static u32	audit_failure = AUDIT_FAIL_PRINTK;
  81
  82/* private audit network namespace index */
  83static unsigned int audit_net_id;
  84
  85/* Number of modules that provide a security context.
  86   List of lsms that provide a security context */
  87static u32 audit_subj_secctx_cnt;
  88static u32 audit_obj_secctx_cnt;
  89static const struct lsm_id *audit_subj_lsms[MAX_LSM_COUNT];
  90static const struct lsm_id *audit_obj_lsms[MAX_LSM_COUNT];
  91
  92/**
  93 * struct audit_net - audit private network namespace data
  94 * @sk: communication socket
  95 */
  96struct audit_net {
  97	struct sock *sk;
  98};
  99
 100/**
 101 * struct auditd_connection - kernel/auditd connection state
 102 * @pid: auditd PID
 103 * @portid: netlink portid
 104 * @net: the associated network namespace
 105 * @rcu: RCU head
 106 *
 107 * Description:
 108 * This struct is RCU protected; you must either hold the RCU lock for reading
 109 * or the associated spinlock for writing.
 110 */
 111struct auditd_connection {
 112	struct pid *pid;
 113	u32 portid;
 114	struct net *net;
 115	struct rcu_head rcu;
 116};
 117static struct auditd_connection __rcu *auditd_conn;
 118static DEFINE_SPINLOCK(auditd_conn_lock);
 119
 120/* If audit_rate_limit is non-zero, limit the rate of sending audit records
 121 * to that number per second.  This prevents DoS attacks, but results in
 122 * audit records being dropped. */
 123static u32	audit_rate_limit;
 124
 125/* Number of outstanding audit_buffers allowed.
 126 * When set to zero, this means unlimited. */
 127static u32	audit_backlog_limit = 64;
 128#define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
 129static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
 130
 131/* The identity of the user shutting down the audit system. */
 132static kuid_t		audit_sig_uid = INVALID_UID;
 133static pid_t		audit_sig_pid = -1;
 134static struct lsm_prop	audit_sig_lsm;
 135
 136/* Records can be lost in several ways:
 137   0) [suppressed in audit_alloc]
 138   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
 139   2) out of memory in audit_log_move [alloc_skb]
 140   3) suppressed due to audit_rate_limit
 141   4) suppressed due to audit_backlog_limit
 142*/
 143static atomic_t	audit_lost = ATOMIC_INIT(0);
 144
 145/* Monotonically increasing sum of time the kernel has spent
 146 * waiting while the backlog limit is exceeded.
 147 */
 148static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0);
 149
 150/* Hash for inode-based rules */
 151struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 152
 153static struct kmem_cache *audit_buffer_cache;
 154
 155/* queue msgs to send via kauditd_task */
 156static struct sk_buff_head audit_queue;
 157/* queue msgs due to temporary unicast send problems */
 158static struct sk_buff_head audit_retry_queue;
 159/* queue msgs waiting for new auditd connection */
 160static struct sk_buff_head audit_hold_queue;
 161
 162/* queue servicing thread */
 163static struct task_struct *kauditd_task;
 164static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 165
 166/* waitqueue for callers who are blocked on the audit backlog */
 167static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 168
 169static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
 170				   .mask = -1,
 171				   .features = 0,
 172				   .lock = 0,};
 173
 174static char *audit_feature_names[2] = {
 175	"only_unset_loginuid",
 176	"loginuid_immutable",
 177};
 178
 179/**
 180 * struct audit_ctl_mutex - serialize requests from userspace
 181 * @lock: the mutex used for locking
 182 * @owner: the task which owns the lock
 183 *
 184 * Description:
 185 * This is the lock struct used to ensure we only process userspace requests
 186 * in an orderly fashion.  We can't simply use a mutex/lock here because we
 187 * need to track lock ownership so we don't end up blocking the lock owner in
 188 * audit_log_start() or similar.
 189 */
 190static struct audit_ctl_mutex {
 191	struct mutex lock;
 192	void *owner;
 193} audit_cmd_mutex;
 194
 195/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 196 * audit records.  Since printk uses a 1024 byte buffer, this buffer
 197 * should be at least that large. */
 198#define AUDIT_BUFSIZ 1024
 199
 200/* The audit_buffer is used when formatting an audit record.  The caller
 201 * locks briefly to get the record off the freelist or to allocate the
 202 * buffer, and locks briefly to send the buffer to the netlink layer or
 203 * to place it on a transmit queue.  Multiple audit_buffers can be in
 204 * use simultaneously. */
 205struct audit_buffer {
 206	struct sk_buff       *skb;	/* the skb for audit_log functions */
 207	struct sk_buff_head  skb_list;	/* formatted skbs, ready to send */
 208	struct audit_context *ctx;	/* NULL or associated context */
 209	struct audit_stamp   stamp;	/* audit stamp for these records */
 210	gfp_t		     gfp_mask;
 211};
 212
 213struct audit_reply {
 214	__u32 portid;
 215	struct net *net;
 216	struct sk_buff *skb;
 217};
 218
 219/**
 220 * auditd_test_task - Check to see if a given task is an audit daemon
 221 * @task: the task to check
 222 *
 223 * Description:
 224 * Return 1 if the task is a registered audit daemon, 0 otherwise.
 225 */
 226int auditd_test_task(struct task_struct *task)
 227{
 228	int rc;
 229	struct auditd_connection *ac;
 230
 231	rcu_read_lock();
 232	ac = rcu_dereference(auditd_conn);
 233	rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
 234	rcu_read_unlock();
 235
 236	return rc;
 237}
 238
 239/**
 240 * audit_ctl_lock - Take the audit control lock
 241 */
 242void audit_ctl_lock(void)
 243{
 244	mutex_lock(&audit_cmd_mutex.lock);
 245	audit_cmd_mutex.owner = current;
 246}
 247
 248/**
 249 * audit_ctl_unlock - Drop the audit control lock
 250 */
 251void audit_ctl_unlock(void)
 252{
 253	audit_cmd_mutex.owner = NULL;
 254	mutex_unlock(&audit_cmd_mutex.lock);
 255}
 256
 257/**
 258 * audit_ctl_owner_current - Test to see if the current task owns the lock
 259 *
 260 * Description:
 261 * Return true if the current task owns the audit control lock, false if it
 262 * doesn't own the lock.
 263 */
 264static bool audit_ctl_owner_current(void)
 265{
 266	return (current == audit_cmd_mutex.owner);
 267}
 268
 269/**
 270 * auditd_pid_vnr - Return the auditd PID relative to the namespace
 271 *
 272 * Description:
 273 * Returns the PID in relation to the namespace, 0 on failure.
 274 */
 275static pid_t auditd_pid_vnr(void)
 276{
 277	pid_t pid;
 278	const struct auditd_connection *ac;
 279
 280	rcu_read_lock();
 281	ac = rcu_dereference(auditd_conn);
 282	if (!ac || !ac->pid)
 283		pid = 0;
 284	else
 285		pid = pid_vnr(ac->pid);
 286	rcu_read_unlock();
 287
 288	return pid;
 289}
 290
 291/**
 292 * audit_cfg_lsm - Identify a security module as providing a secctx.
 293 * @lsmid: LSM identity
 294 * @flags: which contexts are provided
 295 *
 296 * Description:
 297 * Increments the count of the security modules providing a secctx.
 298 * If the LSM id is already in the list leave it alone.
 299 */
 300void audit_cfg_lsm(const struct lsm_id *lsmid, int flags)
 301{
 302	int i;
 303
 304	if (flags & AUDIT_CFG_LSM_SECCTX_SUBJECT) {
 305		for (i = 0 ; i < audit_subj_secctx_cnt; i++)
 306			if (audit_subj_lsms[i] == lsmid)
 307				return;
 308		audit_subj_lsms[audit_subj_secctx_cnt++] = lsmid;
 309	}
 310	if (flags & AUDIT_CFG_LSM_SECCTX_OBJECT) {
 311		for (i = 0 ; i < audit_obj_secctx_cnt; i++)
 312			if (audit_obj_lsms[i] == lsmid)
 313				return;
 314		audit_obj_lsms[audit_obj_secctx_cnt++] = lsmid;
 315	}
 316}
 317
 318/**
 319 * audit_get_sk - Return the audit socket for the given network namespace
 320 * @net: the destination network namespace
 321 *
 322 * Description:
 323 * Returns the sock pointer if valid, NULL otherwise.  The caller must ensure
 324 * that a reference is held for the network namespace while the sock is in use.
 325 */
 326static struct sock *audit_get_sk(const struct net *net)
 327{
 328	struct audit_net *aunet;
 329
 330	if (!net)
 331		return NULL;
 332
 333	aunet = net_generic(net, audit_net_id);
 334	return aunet->sk;
 335}
 336
 337void audit_panic(const char *message)
 338{
 339	switch (audit_failure) {
 340	case AUDIT_FAIL_SILENT:
 341		break;
 342	case AUDIT_FAIL_PRINTK:
 343		if (printk_ratelimit())
 344			pr_err("%s\n", message);
 345		break;
 346	case AUDIT_FAIL_PANIC:
 347		panic("audit: %s\n", message);
 348		break;
 349	}
 350}
 351
 352static inline int audit_rate_check(void)
 353{
 354	static unsigned long	last_check = 0;
 355	static int		messages   = 0;
 356	static DEFINE_SPINLOCK(lock);
 357	unsigned long		flags;
 358	unsigned long		now;
 359	int			retval	   = 0;
 360
 361	if (!audit_rate_limit)
 362		return 1;
 363
 364	spin_lock_irqsave(&lock, flags);
 365	if (++messages < audit_rate_limit) {
 366		retval = 1;
 367	} else {
 368		now = jiffies;
 369		if (time_after(now, last_check + HZ)) {
 370			last_check = now;
 371			messages   = 0;
 372			retval     = 1;
 373		}
 374	}
 375	spin_unlock_irqrestore(&lock, flags);
 376
 377	return retval;
 378}
 379
 380/**
 381 * audit_log_lost - conditionally log lost audit message event
 382 * @message: the message stating reason for lost audit message
 383 *
 384 * Emit at least 1 message per second, even if audit_rate_check is
 385 * throttling.
 386 * Always increment the lost messages counter.
 387*/
 388void audit_log_lost(const char *message)
 389{
 390	static unsigned long	last_msg = 0;
 391	static DEFINE_SPINLOCK(lock);
 392	unsigned long		flags;
 393	unsigned long		now;
 394	int			print;
 395
 396	atomic_inc(&audit_lost);
 397
 398	print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 399
 400	if (!print) {
 401		spin_lock_irqsave(&lock, flags);
 402		now = jiffies;
 403		if (time_after(now, last_msg + HZ)) {
 404			print = 1;
 405			last_msg = now;
 406		}
 407		spin_unlock_irqrestore(&lock, flags);
 408	}
 409
 410	if (print) {
 411		if (printk_ratelimit())
 412			pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
 413				atomic_read(&audit_lost),
 414				audit_rate_limit,
 415				audit_backlog_limit);
 416		audit_panic(message);
 417	}
 418}
 419
 420static int audit_log_config_change(char *function_name, u32 new, u32 old,
 421				   int allow_changes)
 422{
 423	struct audit_buffer *ab;
 424	int rc = 0;
 425
 426	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 427	if (unlikely(!ab))
 428		return rc;
 429	audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
 430	audit_log_session_info(ab);
 431	rc = audit_log_task_context(ab);
 432	if (rc)
 433		allow_changes = 0; /* Something weird, deny request */
 434	audit_log_format(ab, " res=%d", allow_changes);
 435	audit_log_end(ab);
 436	return rc;
 437}
 438
 439static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
 440{
 441	int allow_changes, rc = 0;
 442	u32 old = *to_change;
 443
 444	/* check if we are locked */
 445	if (audit_enabled == AUDIT_LOCKED)
 446		allow_changes = 0;
 447	else
 448		allow_changes = 1;
 449
 450	if (audit_enabled != AUDIT_OFF) {
 451		rc = audit_log_config_change(function_name, new, old, allow_changes);
 452		if (rc)
 453			allow_changes = 0;
 454	}
 455
 456	/* If we are allowed, make the change */
 457	if (allow_changes == 1)
 458		*to_change = new;
 459	/* Not allowed, update reason */
 460	else if (rc == 0)
 461		rc = -EPERM;
 462	return rc;
 463}
 464
 465static int audit_set_rate_limit(u32 limit)
 466{
 467	return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
 468}
 469
 470static int audit_set_backlog_limit(u32 limit)
 471{
 472	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
 473}
 474
 475static int audit_set_backlog_wait_time(u32 timeout)
 476{
 477	return audit_do_config_change("audit_backlog_wait_time",
 478				      &audit_backlog_wait_time, timeout);
 479}
 480
 481static int audit_set_enabled(u32 state)
 482{
 483	int rc;
 484	if (state > AUDIT_LOCKED)
 485		return -EINVAL;
 486
 487	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
 488	if (!rc)
 489		audit_ever_enabled |= !!state;
 490
 491	return rc;
 492}
 493
 494static int audit_set_failure(u32 state)
 495{
 496	if (state != AUDIT_FAIL_SILENT
 497	    && state != AUDIT_FAIL_PRINTK
 498	    && state != AUDIT_FAIL_PANIC)
 499		return -EINVAL;
 500
 501	return audit_do_config_change("audit_failure", &audit_failure, state);
 502}
 503
 504/**
 505 * auditd_conn_free - RCU helper to release an auditd connection struct
 506 * @rcu: RCU head
 507 *
 508 * Description:
 509 * Drop any references inside the auditd connection tracking struct and free
 510 * the memory.
 511 */
 512static void auditd_conn_free(struct rcu_head *rcu)
 513{
 514	struct auditd_connection *ac;
 515
 516	ac = container_of(rcu, struct auditd_connection, rcu);
 517	put_pid(ac->pid);
 518	put_net(ac->net);
 519	kfree(ac);
 520}
 521
 522/**
 523 * auditd_set - Set/Reset the auditd connection state
 524 * @pid: auditd PID
 525 * @portid: auditd netlink portid
 526 * @net: auditd network namespace pointer
 527 * @skb: the netlink command from the audit daemon
 528 * @ack: netlink ack flag, cleared if ack'd here
 529 *
 530 * Description:
 531 * This function will obtain and drop network namespace references as
 532 * necessary.  Returns zero on success, negative values on failure.
 533 */
 534static int auditd_set(struct pid *pid, u32 portid, struct net *net,
 535		      struct sk_buff *skb, bool *ack)
 536{
 537	unsigned long flags;
 538	struct auditd_connection *ac_old, *ac_new;
 539	struct nlmsghdr *nlh;
 540
 541	if (!pid || !net)
 542		return -EINVAL;
 543
 544	ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
 545	if (!ac_new)
 546		return -ENOMEM;
 547	ac_new->pid = get_pid(pid);
 548	ac_new->portid = portid;
 549	ac_new->net = get_net(net);
 550
 551	/* send the ack now to avoid a race with the queue backlog */
 552	if (*ack) {
 553		nlh = nlmsg_hdr(skb);
 554		netlink_ack(skb, nlh, 0, NULL);
 555		*ack = false;
 556	}
 557
 558	spin_lock_irqsave(&auditd_conn_lock, flags);
 559	ac_old = rcu_dereference_protected(auditd_conn,
 560					   lockdep_is_held(&auditd_conn_lock));
 561	rcu_assign_pointer(auditd_conn, ac_new);
 562	spin_unlock_irqrestore(&auditd_conn_lock, flags);
 563
 564	if (ac_old)
 565		call_rcu(&ac_old->rcu, auditd_conn_free);
 566
 567	return 0;
 568}
 569
 570/**
 571 * kauditd_printk_skb - Print the audit record to the ring buffer
 572 * @skb: audit record
 573 *
 574 * Whatever the reason, this packet may not make it to the auditd connection
 575 * so write it via printk so the information isn't completely lost.
 576 */
 577static void kauditd_printk_skb(struct sk_buff *skb)
 578{
 579	struct nlmsghdr *nlh = nlmsg_hdr(skb);
 580	char *data = nlmsg_data(nlh);
 581
 582	if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
 583		pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
 584}
 585
 586/**
 587 * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
 588 * @skb: audit record
 589 * @error: error code (unused)
 590 *
 591 * Description:
 592 * This should only be used by the kauditd_thread when it fails to flush the
 593 * hold queue.
 594 */
 595static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error)
 596{
 597	/* put the record back in the queue */
 598	skb_queue_tail(&audit_hold_queue, skb);
 599}
 600
 601/**
 602 * kauditd_hold_skb - Queue an audit record, waiting for auditd
 603 * @skb: audit record
 604 * @error: error code
 605 *
 606 * Description:
 607 * Queue the audit record, waiting for an instance of auditd.  When this
 608 * function is called we haven't given up yet on sending the record, but things
 609 * are not looking good.  The first thing we want to do is try to write the
 610 * record via printk and then see if we want to try and hold on to the record
 611 * and queue it, if we have room.  If we want to hold on to the record, but we
 612 * don't have room, record a record lost message.
 613 */
 614static void kauditd_hold_skb(struct sk_buff *skb, int error)
 615{
 616	/* at this point it is uncertain if we will ever send this to auditd so
 617	 * try to send the message via printk before we go any further */
 618	kauditd_printk_skb(skb);
 619
 620	/* can we just silently drop the message? */
 621	if (!audit_default)
 622		goto drop;
 623
 624	/* the hold queue is only for when the daemon goes away completely,
 625	 * not -EAGAIN failures; if we are in a -EAGAIN state requeue the
 626	 * record on the retry queue unless it's full, in which case drop it
 627	 */
 628	if (error == -EAGAIN) {
 629		if (!audit_backlog_limit ||
 630		    skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
 631			skb_queue_tail(&audit_retry_queue, skb);
 632			return;
 633		}
 634		audit_log_lost("kauditd retry queue overflow");
 635		goto drop;
 636	}
 637
 638	/* if we have room in the hold queue, queue the message */
 639	if (!audit_backlog_limit ||
 640	    skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
 641		skb_queue_tail(&audit_hold_queue, skb);
 642		return;
 643	}
 644
 645	/* we have no other options - drop the message */
 646	audit_log_lost("kauditd hold queue overflow");
 647drop:
 648	kfree_skb(skb);
 649}
 650
 651/**
 652 * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
 653 * @skb: audit record
 654 * @error: error code (unused)
 655 *
 656 * Description:
 657 * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
 658 * but for some reason we are having problems sending it audit records so
 659 * queue the given record and attempt to resend.
 660 */
 661static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error)
 662{
 663	if (!audit_backlog_limit ||
 664	    skb_queue_len(&audit_retry_queue) < audit_backlog_limit) {
 665		skb_queue_tail(&audit_retry_queue, skb);
 666		return;
 667	}
 668
 669	/* we have to drop the record, send it via printk as a last effort */
 670	kauditd_printk_skb(skb);
 671	audit_log_lost("kauditd retry queue overflow");
 672	kfree_skb(skb);
 673}
 674
 675/**
 676 * auditd_reset - Disconnect the auditd connection
 677 * @ac: auditd connection state
 678 *
 679 * Description:
 680 * Break the auditd/kauditd connection and move all the queued records into the
 681 * hold queue in case auditd reconnects.  It is important to note that the @ac
 682 * pointer should never be dereferenced inside this function as it may be NULL
 683 * or invalid, you can only compare the memory address!  If @ac is NULL then
 684 * the connection will always be reset.
 685 */
 686static void auditd_reset(const struct auditd_connection *ac)
 687{
 688	unsigned long flags;
 689	struct sk_buff *skb;
 690	struct auditd_connection *ac_old;
 691
 692	/* if it isn't already broken, break the connection */
 693	spin_lock_irqsave(&auditd_conn_lock, flags);
 694	ac_old = rcu_dereference_protected(auditd_conn,
 695					   lockdep_is_held(&auditd_conn_lock));
 696	if (ac && ac != ac_old) {
 697		/* someone already registered a new auditd connection */
 698		spin_unlock_irqrestore(&auditd_conn_lock, flags);
 699		return;
 700	}
 701	rcu_assign_pointer(auditd_conn, NULL);
 702	spin_unlock_irqrestore(&auditd_conn_lock, flags);
 703
 704	if (ac_old)
 705		call_rcu(&ac_old->rcu, auditd_conn_free);
 706
 707	/* flush the retry queue to the hold queue, but don't touch the main
 708	 * queue since we need to process that normally for multicast */
 709	while ((skb = skb_dequeue(&audit_retry_queue)))
 710		kauditd_hold_skb(skb, -ECONNREFUSED);
 711}
 712
 713/**
 714 * auditd_send_unicast_skb - Send a record via unicast to auditd
 715 * @skb: audit record
 716 *
 717 * Description:
 718 * Send a skb to the audit daemon, returns positive/zero values on success and
 719 * negative values on failure; in all cases the skb will be consumed by this
 720 * function.  If the send results in -ECONNREFUSED the connection with auditd
 721 * will be reset.  This function may sleep so callers should not hold any locks
 722 * where this would cause a problem.
 723 */
 724static int auditd_send_unicast_skb(struct sk_buff *skb)
 725{
 726	int rc;
 727	u32 portid;
 728	struct net *net;
 729	struct sock *sk;
 730	struct auditd_connection *ac;
 731
 732	/* NOTE: we can't call netlink_unicast while in the RCU section so
 733	 *       take a reference to the network namespace and grab local
 734	 *       copies of the namespace, the sock, and the portid; the
 735	 *       namespace and sock aren't going to go away while we hold a
 736	 *       reference and if the portid does become invalid after the RCU
 737	 *       section netlink_unicast() should safely return an error */
 738
 739	rcu_read_lock();
 740	ac = rcu_dereference(auditd_conn);
 741	if (!ac) {
 742		rcu_read_unlock();
 743		kfree_skb(skb);
 744		rc = -ECONNREFUSED;
 745		goto err;
 746	}
 747	net = get_net(ac->net);
 748	sk = audit_get_sk(net);
 749	portid = ac->portid;
 750	rcu_read_unlock();
 751
 752	rc = netlink_unicast(sk, skb, portid, 0);
 753	put_net(net);
 754	if (rc < 0)
 755		goto err;
 756
 757	return rc;
 758
 759err:
 760	if (ac && rc == -ECONNREFUSED)
 761		auditd_reset(ac);
 762	return rc;
 763}
 764
 765/**
 766 * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
 767 * @sk: the sending sock
 768 * @portid: the netlink destination
 769 * @queue: the skb queue to process
 770 * @retry_limit: limit on number of netlink unicast failures
 771 * @skb_hook: per-skb hook for additional processing
 772 * @err_hook: hook called if the skb fails the netlink unicast send
 773 *
 774 * Description:
 775 * Run through the given queue and attempt to send the audit records to auditd,
 776 * returns zero on success, negative values on failure.  It is up to the caller
 777 * to ensure that the @sk is valid for the duration of this function.
 778 *
 779 */
 780static int kauditd_send_queue(struct sock *sk, u32 portid,
 781			      struct sk_buff_head *queue,
 782			      unsigned int retry_limit,
 783			      void (*skb_hook)(struct sk_buff *skb),
 784			      void (*err_hook)(struct sk_buff *skb, int error))
 785{
 786	int rc = 0;
 787	struct sk_buff *skb = NULL;
 788	struct sk_buff *skb_tail;
 789	unsigned int failed = 0;
 790
 791	/* NOTE: kauditd_thread takes care of all our locking, we just use
 792	 *       the netlink info passed to us (e.g. sk and portid) */
 793
 794	skb_tail = skb_peek_tail(queue);
 795	while ((skb != skb_tail) && (skb = skb_dequeue(queue))) {
 796		/* call the skb_hook for each skb we touch */
 797		if (skb_hook)
 798			(*skb_hook)(skb);
 799
 800		/* can we send to anyone via unicast? */
 801		if (!sk) {
 802			if (err_hook)
 803				(*err_hook)(skb, -ECONNREFUSED);
 804			continue;
 805		}
 806
 807retry:
 808		/* grab an extra skb reference in case of error */
 809		skb_get(skb);
 810		rc = netlink_unicast(sk, skb, portid, 0);
 811		if (rc < 0) {
 812			/* send failed - try a few times unless fatal error */
 813			if (++failed >= retry_limit ||
 814			    rc == -ECONNREFUSED || rc == -EPERM) {
 815				sk = NULL;
 816				if (err_hook)
 817					(*err_hook)(skb, rc);
 818				if (rc == -EAGAIN)
 819					rc = 0;
 820				/* continue to drain the queue */
 821				continue;
 822			} else
 823				goto retry;
 824		} else {
 825			/* skb sent - drop the extra reference and continue */
 826			consume_skb(skb);
 827			failed = 0;
 828		}
 829	}
 830
 831	return (rc >= 0 ? 0 : rc);
 832}
 833
 834/*
 835 * kauditd_send_multicast_skb - Send a record to any multicast listeners
 836 * @skb: audit record
 837 *
 838 * Description:
 839 * Write a multicast message to anyone listening in the initial network
 840 * namespace.  This function doesn't consume an skb as might be expected since
 841 * it has to copy it anyways.
 842 */
 843static void kauditd_send_multicast_skb(struct sk_buff *skb)
 844{
 845	struct sk_buff *copy;
 846	struct sock *sock = audit_get_sk(&init_net);
 847	struct nlmsghdr *nlh;
 848
 849	/* NOTE: we are not taking an additional reference for init_net since
 850	 *       we don't have to worry about it going away */
 851
 852	if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
 853		return;
 854
 855	/*
 856	 * The seemingly wasteful skb_copy() rather than bumping the refcount
 857	 * using skb_get() is necessary because non-standard mods are made to
 858	 * the skb by the original kaudit unicast socket send routine.  The
 859	 * existing auditd daemon assumes this breakage.  Fixing this would
 860	 * require co-ordinating a change in the established protocol between
 861	 * the kaudit kernel subsystem and the auditd userspace code.  There is
 862	 * no reason for new multicast clients to continue with this
 863	 * non-compliance.
 864	 */
 865	copy = skb_copy(skb, GFP_KERNEL);
 866	if (!copy)
 867		return;
 868	nlh = nlmsg_hdr(copy);
 869	nlh->nlmsg_len = skb->len;
 870
 871	nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
 872}
 873
 874/**
 875 * kauditd_thread - Worker thread to send audit records to userspace
 876 * @dummy: unused
 877 */
 878static int kauditd_thread(void *dummy)
 879{
 880	int rc;
 881	u32 portid = 0;
 882	struct net *net = NULL;
 883	struct sock *sk = NULL;
 884	struct auditd_connection *ac;
 885
 886#define UNICAST_RETRIES 5
 887
 888	set_freezable();
 889	while (!kthread_should_stop()) {
 890		/* NOTE: see the lock comments in auditd_send_unicast_skb() */
 891		rcu_read_lock();
 892		ac = rcu_dereference(auditd_conn);
 893		if (!ac) {
 894			rcu_read_unlock();
 895			goto main_queue;
 896		}
 897		net = get_net(ac->net);
 898		sk = audit_get_sk(net);
 899		portid = ac->portid;
 900		rcu_read_unlock();
 901
 902		/* attempt to flush the hold queue */
 903		rc = kauditd_send_queue(sk, portid,
 904					&audit_hold_queue, UNICAST_RETRIES,
 905					NULL, kauditd_rehold_skb);
 906		if (rc < 0) {
 907			sk = NULL;
 908			auditd_reset(ac);
 909			goto main_queue;
 910		}
 911
 912		/* attempt to flush the retry queue */
 913		rc = kauditd_send_queue(sk, portid,
 914					&audit_retry_queue, UNICAST_RETRIES,
 915					NULL, kauditd_hold_skb);
 916		if (rc < 0) {
 917			sk = NULL;
 918			auditd_reset(ac);
 919			goto main_queue;
 920		}
 921
 922main_queue:
 923		/* process the main queue - do the multicast send and attempt
 924		 * unicast, dump failed record sends to the retry queue; if
 925		 * sk == NULL due to previous failures we will just do the
 926		 * multicast send and move the record to the hold queue */
 927		rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
 928					kauditd_send_multicast_skb,
 929					(sk ?
 930					 kauditd_retry_skb : kauditd_hold_skb));
 931		if (ac && rc < 0)
 932			auditd_reset(ac);
 933		sk = NULL;
 934
 935		/* drop our netns reference, no auditd sends past this line */
 936		if (net) {
 937			put_net(net);
 938			net = NULL;
 939		}
 940
 941		/* we have processed all the queues so wake everyone */
 942		wake_up(&audit_backlog_wait);
 943
 944		/* NOTE: we want to wake up if there is anything on the queue,
 945		 *       regardless of if an auditd is connected, as we need to
 946		 *       do the multicast send and rotate records from the
 947		 *       main queue to the retry/hold queues */
 948		wait_event_freezable(kauditd_wait,
 949				     (skb_queue_len(&audit_queue) ? 1 : 0));
 950	}
 951
 952	return 0;
 953}
 954
 955int audit_send_list_thread(void *_dest)
 956{
 957	struct audit_netlink_list *dest = _dest;
 958	struct sk_buff *skb;
 959	struct sock *sk = audit_get_sk(dest->net);
 960
 961	/* wait for parent to finish and send an ACK */
 962	audit_ctl_lock();
 963	audit_ctl_unlock();
 964
 965	while ((skb = __skb_dequeue(&dest->q)) != NULL)
 966		netlink_unicast(sk, skb, dest->portid, 0);
 967
 968	put_net(dest->net);
 969	kfree(dest);
 970
 971	return 0;
 972}
 973
 974struct sk_buff *audit_make_reply(int seq, int type, int done,
 975				 int multi, const void *payload, int size)
 976{
 977	struct sk_buff	*skb;
 978	struct nlmsghdr	*nlh;
 979	void		*data;
 980	int		flags = multi ? NLM_F_MULTI : 0;
 981	int		t     = done  ? NLMSG_DONE  : type;
 982
 983	skb = nlmsg_new(size, GFP_KERNEL);
 984	if (!skb)
 985		return NULL;
 986
 987	nlh	= nlmsg_put(skb, 0, seq, t, size, flags);
 988	if (!nlh)
 989		goto out_kfree_skb;
 990	data = nlmsg_data(nlh);
 991	memcpy(data, payload, size);
 992	return skb;
 993
 994out_kfree_skb:
 995	kfree_skb(skb);
 996	return NULL;
 997}
 998
 999static void audit_free_reply(struct audit_reply *reply)
1000{
1001	if (!reply)
1002		return;
1003
1004	kfree_skb(reply->skb);
1005	if (reply->net)
1006		put_net(reply->net);
1007	kfree(reply);
1008}
1009
1010static int audit_send_reply_thread(void *arg)
1011{
1012	struct audit_reply *reply = (struct audit_reply *)arg;
1013
1014	audit_ctl_lock();
1015	audit_ctl_unlock();
1016
1017	/* Ignore failure. It'll only happen if the sender goes away,
1018	   because our timeout is set to infinite. */
1019	netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0);
1020	reply->skb = NULL;
1021	audit_free_reply(reply);
1022	return 0;
1023}
1024
1025/**
1026 * audit_send_reply - send an audit reply message via netlink
1027 * @request_skb: skb of request we are replying to (used to target the reply)
1028 * @seq: sequence number
1029 * @type: audit message type
1030 * @done: done (last) flag
1031 * @multi: multi-part message flag
1032 * @payload: payload data
1033 * @size: payload size
1034 *
1035 * Allocates a skb, builds the netlink message, and sends it to the port id.
1036 */
1037static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
1038			     int multi, const void *payload, int size)
1039{
1040	struct task_struct *tsk;
1041	struct audit_reply *reply;
1042
1043	reply = kzalloc(sizeof(*reply), GFP_KERNEL);
1044	if (!reply)
1045		return;
1046
1047	reply->skb = audit_make_reply(seq, type, done, multi, payload, size);
1048	if (!reply->skb)
1049		goto err;
1050	reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk));
1051	reply->portid = NETLINK_CB(request_skb).portid;
1052
1053	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
1054	if (IS_ERR(tsk))
1055		goto err;
1056
1057	return;
1058
1059err:
1060	audit_free_reply(reply);
1061}
1062
1063/*
1064 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
1065 * control messages.
1066 */
1067static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
1068{
1069	int err = 0;
1070
1071	/* Only support initial user namespace for now. */
1072	/*
1073	 * We return ECONNREFUSED because it tricks userspace into thinking
1074	 * that audit was not configured into the kernel.  Lots of users
1075	 * configure their PAM stack (because that's what the distro does)
1076	 * to reject login if unable to send messages to audit.  If we return
1077	 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
1078	 * configured in and will let login proceed.  If we return EPERM
1079	 * userspace will reject all logins.  This should be removed when we
1080	 * support non init namespaces!!
1081	 */
1082	if (current_user_ns() != &init_user_ns)
1083		return -ECONNREFUSED;
1084
1085	switch (msg_type) {
1086	case AUDIT_LIST:
1087	case AUDIT_ADD:
1088	case AUDIT_DEL:
1089		return -EOPNOTSUPP;
1090	case AUDIT_GET:
1091	case AUDIT_SET:
1092	case AUDIT_GET_FEATURE:
1093	case AUDIT_SET_FEATURE:
1094	case AUDIT_LIST_RULES:
1095	case AUDIT_ADD_RULE:
1096	case AUDIT_DEL_RULE:
1097	case AUDIT_SIGNAL_INFO:
1098	case AUDIT_TTY_GET:
1099	case AUDIT_TTY_SET:
1100	case AUDIT_TRIM:
1101	case AUDIT_MAKE_EQUIV:
1102		/* Only support auditd and auditctl in initial pid namespace
1103		 * for now. */
1104		if (task_active_pid_ns(current) != &init_pid_ns)
1105			return -EPERM;
1106
1107		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1108			err = -EPERM;
1109		break;
1110	case AUDIT_USER:
1111	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1112	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1113		if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1114			err = -EPERM;
1115		break;
1116	default:  /* bad msg */
1117		err = -EINVAL;
1118	}
1119
1120	return err;
1121}
1122
1123static void audit_log_common_recv_msg(struct audit_context *context,
1124					struct audit_buffer **ab, u16 msg_type)
1125{
1126	uid_t uid = from_kuid(&init_user_ns, current_uid());
1127	pid_t pid = task_tgid_nr(current);
1128
1129	if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1130		*ab = NULL;
1131		return;
1132	}
1133
1134	*ab = audit_log_start(context, GFP_KERNEL, msg_type);
1135	if (unlikely(!*ab))
1136		return;
1137	audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1138	audit_log_session_info(*ab);
1139	audit_log_task_context(*ab);
1140}
1141
1142static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1143					   u16 msg_type)
1144{
1145	audit_log_common_recv_msg(NULL, ab, msg_type);
1146}
1147
1148static int is_audit_feature_set(int i)
1149{
1150	return af.features & AUDIT_FEATURE_TO_MASK(i);
1151}
1152
1153static int audit_get_feature(struct sk_buff *skb)
1154{
1155	u32 seq;
1156
1157	seq = nlmsg_hdr(skb)->nlmsg_seq;
1158
1159	audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1160
1161	return 0;
1162}
1163
1164static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1165				     u32 old_lock, u32 new_lock, int res)
1166{
1167	struct audit_buffer *ab;
1168
1169	if (audit_enabled == AUDIT_OFF)
1170		return;
1171
1172	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1173	if (!ab)
1174		return;
1175	audit_log_task_info(ab);
1176	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1177			 audit_feature_names[which], !!old_feature, !!new_feature,
1178			 !!old_lock, !!new_lock, res);
1179	audit_log_end(ab);
1180}
1181
1182static int audit_set_feature(struct audit_features *uaf)
1183{
1184	int i;
1185
1186	BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1187
1188	/* if there is ever a version 2 we should handle that here */
1189
1190	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1191		u32 feature = AUDIT_FEATURE_TO_MASK(i);
1192		u32 old_feature, new_feature, old_lock, new_lock;
1193
1194		/* if we are not changing this feature, move along */
1195		if (!(feature & uaf->mask))
1196			continue;
1197
1198		old_feature = af.features & feature;
1199		new_feature = uaf->features & feature;
1200		new_lock = (uaf->lock | af.lock) & feature;
1201		old_lock = af.lock & feature;
1202
1203		/* are we changing a locked feature? */
1204		if (old_lock && (new_feature != old_feature)) {
1205			audit_log_feature_change(i, old_feature, new_feature,
1206						 old_lock, new_lock, 0);
1207			return -EPERM;
1208		}
1209	}
1210	/* nothing invalid, do the changes */
1211	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1212		u32 feature = AUDIT_FEATURE_TO_MASK(i);
1213		u32 old_feature, new_feature, old_lock, new_lock;
1214
1215		/* if we are not changing this feature, move along */
1216		if (!(feature & uaf->mask))
1217			continue;
1218
1219		old_feature = af.features & feature;
1220		new_feature = uaf->features & feature;
1221		old_lock = af.lock & feature;
1222		new_lock = (uaf->lock | af.lock) & feature;
1223
1224		if (new_feature != old_feature)
1225			audit_log_feature_change(i, old_feature, new_feature,
1226						 old_lock, new_lock, 1);
1227
1228		if (new_feature)
1229			af.features |= feature;
1230		else
1231			af.features &= ~feature;
1232		af.lock |= new_lock;
1233	}
1234
1235	return 0;
1236}
1237
1238static int audit_replace(struct pid *pid)
1239{
1240	pid_t pvnr;
1241	struct sk_buff *skb;
1242
1243	pvnr = pid_vnr(pid);
1244	skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1245	if (!skb)
1246		return -ENOMEM;
1247	return auditd_send_unicast_skb(skb);
1248}
1249
1250static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
1251			     bool *ack)
1252{
1253	u32			seq;
1254	void			*data;
1255	int			data_len;
1256	int			err;
1257	struct audit_buffer	*ab;
1258	u16			msg_type = nlh->nlmsg_type;
1259	struct audit_sig_info   *sig_data;
1260	struct lsm_context	lsmctx = { NULL, 0, 0 };
1261
1262	err = audit_netlink_ok(skb, msg_type);
1263	if (err)
1264		return err;
1265
1266	seq  = nlh->nlmsg_seq;
1267	data = nlmsg_data(nlh);
1268	data_len = nlmsg_len(nlh);
1269
1270	switch (msg_type) {
1271	case AUDIT_GET: {
1272		struct audit_status	s;
1273		memset(&s, 0, sizeof(s));
1274		s.enabled		   = audit_enabled;
1275		s.failure		   = audit_failure;
1276		/* NOTE: use pid_vnr() so the PID is relative to the current
1277		 *       namespace */
1278		s.pid			   = auditd_pid_vnr();
1279		s.rate_limit		   = audit_rate_limit;
1280		s.backlog_limit		   = audit_backlog_limit;
1281		s.lost			   = atomic_read(&audit_lost);
1282		s.backlog		   = skb_queue_len(&audit_queue);
1283		s.feature_bitmap	   = AUDIT_FEATURE_BITMAP_ALL;
1284		s.backlog_wait_time	   = audit_backlog_wait_time;
1285		s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual);
1286		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1287		break;
1288	}
1289	case AUDIT_SET: {
1290		struct audit_status	s;
1291		memset(&s, 0, sizeof(s));
1292		/* guard against past and future API changes */
1293		memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1294		if (s.mask & AUDIT_STATUS_ENABLED) {
1295			err = audit_set_enabled(s.enabled);
1296			if (err < 0)
1297				return err;
1298		}
1299		if (s.mask & AUDIT_STATUS_FAILURE) {
1300			err = audit_set_failure(s.failure);
1301			if (err < 0)
1302				return err;
1303		}
1304		if (s.mask & AUDIT_STATUS_PID) {
1305			/* NOTE: we are using the vnr PID functions below
1306			 *       because the s.pid value is relative to the
1307			 *       namespace of the caller; at present this
1308			 *       doesn't matter much since you can really only
1309			 *       run auditd from the initial pid namespace, but
1310			 *       something to keep in mind if this changes */
1311			pid_t new_pid = s.pid;
1312			pid_t auditd_pid;
1313			struct pid *req_pid = task_tgid(current);
1314
1315			/* Sanity check - PID values must match. Setting
1316			 * pid to 0 is how auditd ends auditing. */
1317			if (new_pid && (new_pid != pid_vnr(req_pid)))
1318				return -EINVAL;
1319
1320			/* test the auditd connection */
1321			audit_replace(req_pid);
1322
1323			auditd_pid = auditd_pid_vnr();
1324			if (auditd_pid) {
1325				/* replacing a healthy auditd is not allowed */
1326				if (new_pid) {
1327					audit_log_config_change("audit_pid",
1328							new_pid, auditd_pid, 0);
1329					return -EEXIST;
1330				}
1331				/* only current auditd can unregister itself */
1332				if (pid_vnr(req_pid) != auditd_pid) {
1333					audit_log_config_change("audit_pid",
1334							new_pid, auditd_pid, 0);
1335					return -EACCES;
1336				}
1337			}
1338
1339			if (new_pid) {
1340				/* register a new auditd connection */
1341				err = auditd_set(req_pid,
1342						 NETLINK_CB(skb).portid,
1343						 sock_net(NETLINK_CB(skb).sk),
1344						 skb, ack);
1345				if (audit_enabled != AUDIT_OFF)
1346					audit_log_config_change("audit_pid",
1347								new_pid,
1348								auditd_pid,
1349								err ? 0 : 1);
1350				if (err)
1351					return err;
1352
1353				/* try to process any backlog */
1354				wake_up_interruptible(&kauditd_wait);
1355			} else {
1356				if (audit_enabled != AUDIT_OFF)
1357					audit_log_config_change("audit_pid",
1358								new_pid,
1359								auditd_pid, 1);
1360
1361				/* unregister the auditd connection */
1362				auditd_reset(NULL);
1363			}
1364		}
1365		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1366			err = audit_set_rate_limit(s.rate_limit);
1367			if (err < 0)
1368				return err;
1369		}
1370		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1371			err = audit_set_backlog_limit(s.backlog_limit);
1372			if (err < 0)
1373				return err;
1374		}
1375		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1376			if (sizeof(s) > (size_t)nlh->nlmsg_len)
1377				return -EINVAL;
1378			if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1379				return -EINVAL;
1380			err = audit_set_backlog_wait_time(s.backlog_wait_time);
1381			if (err < 0)
1382				return err;
1383		}
1384		if (s.mask == AUDIT_STATUS_LOST) {
1385			u32 lost = atomic_xchg(&audit_lost, 0);
1386
1387			audit_log_config_change("lost", 0, lost, 1);
1388			return lost;
1389		}
1390		if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) {
1391			u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0);
1392
1393			audit_log_config_change("backlog_wait_time_actual", 0, actual, 1);
1394			return actual;
1395		}
1396		break;
1397	}
1398	case AUDIT_GET_FEATURE:
1399		err = audit_get_feature(skb);
1400		if (err)
1401			return err;
1402		break;
1403	case AUDIT_SET_FEATURE:
1404		if (data_len < sizeof(struct audit_features))
1405			return -EINVAL;
1406		err = audit_set_feature(data);
1407		if (err)
1408			return err;
1409		break;
1410	case AUDIT_USER:
1411	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1412	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1413		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1414			return 0;
1415		/* exit early if there isn't at least one character to print */
1416		if (data_len < 2)
1417			return -EINVAL;
1418
1419		err = audit_filter(msg_type, AUDIT_FILTER_USER);
1420		if (err == 1) { /* match or error */
1421			char *str = data;
1422
1423			err = 0;
1424			if (msg_type == AUDIT_USER_TTY) {
1425				err = tty_audit_push();
1426				if (err)
1427					break;
1428			}
1429			audit_log_user_recv_msg(&ab, msg_type);
1430			if (msg_type != AUDIT_USER_TTY) {
1431				/* ensure NULL termination */
1432				str[data_len - 1] = '\0';
1433				audit_log_format(ab, " msg='%.*s'",
1434						 AUDIT_MESSAGE_TEXT_MAX,
1435						 str);
1436			} else {
1437				audit_log_format(ab, " data=");
1438				if (str[data_len - 1] == '\0')
1439					data_len--;
1440				audit_log_n_untrustedstring(ab, str, data_len);
1441			}
1442			audit_log_end(ab);
1443		}
1444		break;
1445	case AUDIT_ADD_RULE:
1446	case AUDIT_DEL_RULE:
1447		if (data_len < sizeof(struct audit_rule_data))
1448			return -EINVAL;
1449		if (audit_enabled == AUDIT_LOCKED) {
1450			audit_log_common_recv_msg(audit_context(), &ab,
1451						  AUDIT_CONFIG_CHANGE);
1452			audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1453					 msg_type == AUDIT_ADD_RULE ?
1454						"add_rule" : "remove_rule",
1455					 audit_enabled);
1456			audit_log_end(ab);
1457			return -EPERM;
1458		}
1459		err = audit_rule_change(msg_type, seq, data, data_len);
1460		break;
1461	case AUDIT_LIST_RULES:
1462		err = audit_list_rules_send(skb, seq);
1463		break;
1464	case AUDIT_TRIM:
1465		audit_trim_trees();
1466		audit_log_common_recv_msg(audit_context(), &ab,
1467					  AUDIT_CONFIG_CHANGE);
1468		audit_log_format(ab, " op=trim res=1");
1469		audit_log_end(ab);
1470		break;
1471	case AUDIT_MAKE_EQUIV: {
1472		void *bufp = data;
1473		u32 sizes[2];
1474		size_t msglen = data_len;
1475		char *old, *new;
1476
1477		err = -EINVAL;
1478		if (msglen < 2 * sizeof(u32))
1479			break;
1480		memcpy(sizes, bufp, 2 * sizeof(u32));
1481		bufp += 2 * sizeof(u32);
1482		msglen -= 2 * sizeof(u32);
1483		old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1484		if (IS_ERR(old)) {
1485			err = PTR_ERR(old);
1486			break;
1487		}
1488		new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1489		if (IS_ERR(new)) {
1490			err = PTR_ERR(new);
1491			kfree(old);
1492			break;
1493		}
1494		/* OK, here comes... */
1495		err = audit_tag_tree(old, new);
1496
1497		audit_log_common_recv_msg(audit_context(), &ab,
1498					  AUDIT_CONFIG_CHANGE);
1499		audit_log_format(ab, " op=make_equiv old=");
1500		audit_log_untrustedstring(ab, old);
1501		audit_log_format(ab, " new=");
1502		audit_log_untrustedstring(ab, new);
1503		audit_log_format(ab, " res=%d", !err);
1504		audit_log_end(ab);
1505		kfree(old);
1506		kfree(new);
1507		break;
1508	}
1509	case AUDIT_SIGNAL_INFO:
1510		if (lsmprop_is_set(&audit_sig_lsm)) {
1511			err = security_lsmprop_to_secctx(&audit_sig_lsm,
1512							 &lsmctx, LSM_ID_UNDEF);
1513			if (err < 0)
1514				return err;
1515		}
1516		sig_data = kmalloc(struct_size(sig_data, ctx, lsmctx.len),
1517				   GFP_KERNEL);
1518		if (!sig_data) {
1519			if (lsmprop_is_set(&audit_sig_lsm))
1520				security_release_secctx(&lsmctx);
1521			return -ENOMEM;
1522		}
1523		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1524		sig_data->pid = audit_sig_pid;
1525		if (lsmprop_is_set(&audit_sig_lsm)) {
1526			memcpy(sig_data->ctx, lsmctx.context, lsmctx.len);
1527			security_release_secctx(&lsmctx);
1528		}
1529		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1530				 sig_data, struct_size(sig_data, ctx,
1531						       lsmctx.len));
1532		kfree(sig_data);
1533		break;
1534	case AUDIT_TTY_GET: {
1535		struct audit_tty_status s;
1536		unsigned int t;
1537
1538		t = READ_ONCE(current->signal->audit_tty);
1539		s.enabled = t & AUDIT_TTY_ENABLE;
1540		s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1541
1542		audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1543		break;
1544	}
1545	case AUDIT_TTY_SET: {
1546		struct audit_tty_status s, old;
1547		struct audit_buffer	*ab;
1548		unsigned int t;
1549
1550		memset(&s, 0, sizeof(s));
1551		/* guard against past and future API changes */
1552		memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1553		/* check if new data is valid */
1554		if ((s.enabled != 0 && s.enabled != 1) ||
1555		    (s.log_passwd != 0 && s.log_passwd != 1))
1556			err = -EINVAL;
1557
1558		if (err)
1559			t = READ_ONCE(current->signal->audit_tty);
1560		else {
1561			t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1562			t = xchg(&current->signal->audit_tty, t);
1563		}
1564		old.enabled = t & AUDIT_TTY_ENABLE;
1565		old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1566
1567		audit_log_common_recv_msg(audit_context(), &ab,
1568					  AUDIT_CONFIG_CHANGE);
1569		audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1570				 " old-log_passwd=%d new-log_passwd=%d res=%d",
1571				 old.enabled, s.enabled, old.log_passwd,
1572				 s.log_passwd, !err);
1573		audit_log_end(ab);
1574		break;
1575	}
1576	default:
1577		err = -EINVAL;
1578		break;
1579	}
1580
1581	return err < 0 ? err : 0;
1582}
1583
1584/**
1585 * audit_receive - receive messages from a netlink control socket
1586 * @skb: the message buffer
1587 *
1588 * Parse the provided skb and deal with any messages that may be present,
1589 * malformed skbs are discarded.
1590 */
1591static void audit_receive(struct sk_buff *skb)
1592{
1593	struct nlmsghdr *nlh;
1594	bool ack;
1595	/*
1596	 * len MUST be signed for nlmsg_next to be able to dec it below 0
1597	 * if the nlmsg_len was not aligned
1598	 */
1599	int len;
1600	int err;
1601
1602	nlh = nlmsg_hdr(skb);
1603	len = skb->len;
1604
1605	audit_ctl_lock();
1606	while (nlmsg_ok(nlh, len)) {
1607		ack = nlh->nlmsg_flags & NLM_F_ACK;
1608		err = audit_receive_msg(skb, nlh, &ack);
1609
1610		/* send an ack if the user asked for one and audit_receive_msg
1611		 * didn't already do it, or if there was an error. */
1612		if (ack || err)
1613			netlink_ack(skb, nlh, err, NULL);
1614
1615		nlh = nlmsg_next(nlh, &len);
1616	}
1617	audit_ctl_unlock();
1618
1619	/* can't block with the ctrl lock, so penalize the sender now */
1620	if (audit_backlog_limit &&
1621	    (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1622		DECLARE_WAITQUEUE(wait, current);
1623
1624		/* wake kauditd to try and flush the queue */
1625		wake_up_interruptible(&kauditd_wait);
1626
1627		add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1628		set_current_state(TASK_UNINTERRUPTIBLE);
1629		schedule_timeout(audit_backlog_wait_time);
1630		remove_wait_queue(&audit_backlog_wait, &wait);
1631	}
1632}
1633
1634/* Log information about who is connecting to the audit multicast socket */
1635static void audit_log_multicast(int group, const char *op, int err)
1636{
1637	const struct cred *cred;
1638	struct tty_struct *tty;
1639	char comm[sizeof(current->comm)];
1640	struct audit_buffer *ab;
1641
1642	if (!audit_enabled)
1643		return;
1644
1645	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER);
1646	if (!ab)
1647		return;
1648
1649	cred = current_cred();
1650	tty = audit_get_tty();
1651	audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u",
1652			 task_tgid_nr(current),
1653			 from_kuid(&init_user_ns, cred->uid),
1654			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
1655			 tty ? tty_name(tty) : "(none)",
1656			 audit_get_sessionid(current));
1657	audit_put_tty(tty);
1658	audit_log_task_context(ab); /* subj= */
1659	audit_log_format(ab, " comm=");
1660	audit_log_untrustedstring(ab, get_task_comm(comm, current));
1661	audit_log_d_path_exe(ab, current->mm); /* exe= */
1662	audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err);
1663	audit_log_end(ab);
1664}
1665
1666/* Run custom bind function on netlink socket group connect or bind requests. */
1667static int audit_multicast_bind(struct net *net, int group)
1668{
1669	int err = 0;
1670
1671	if (!capable(CAP_AUDIT_READ))
1672		err = -EPERM;
1673	audit_log_multicast(group, "connect", err);
1674	return err;
1675}
1676
1677static void audit_multicast_unbind(struct net *net, int group)
1678{
1679	audit_log_multicast(group, "disconnect", 0);
1680}
1681
1682static int __net_init audit_net_init(struct net *net)
1683{
1684	struct netlink_kernel_cfg cfg = {
1685		.input	= audit_receive,
1686		.bind	= audit_multicast_bind,
1687		.unbind	= audit_multicast_unbind,
1688		.flags	= NL_CFG_F_NONROOT_RECV,
1689		.groups	= AUDIT_NLGRP_MAX,
1690	};
1691
1692	struct audit_net *aunet = net_generic(net, audit_net_id);
1693
1694	aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1695	if (aunet->sk == NULL) {
1696		audit_panic("cannot initialize netlink socket in namespace");
1697		return -ENOMEM;
1698	}
1699	/* limit the timeout in case auditd is blocked/stopped */
1700	aunet->sk->sk_sndtimeo = HZ / 10;
1701
1702	return 0;
1703}
1704
1705static void __net_exit audit_net_exit(struct net *net)
1706{
1707	struct audit_net *aunet = net_generic(net, audit_net_id);
1708
1709	/* NOTE: you would think that we would want to check the auditd
1710	 * connection and potentially reset it here if it lives in this
1711	 * namespace, but since the auditd connection tracking struct holds a
1712	 * reference to this namespace (see auditd_set()) we are only ever
1713	 * going to get here after that connection has been released */
1714
1715	netlink_kernel_release(aunet->sk);
1716}
1717
1718static struct pernet_operations audit_net_ops __net_initdata = {
1719	.init = audit_net_init,
1720	.exit = audit_net_exit,
1721	.id = &audit_net_id,
1722	.size = sizeof(struct audit_net),
1723};
1724
1725/* Initialize audit support at boot time. */
1726static int __init audit_init(void)
1727{
1728	int i;
1729
1730	if (audit_initialized == AUDIT_DISABLED)
1731		return 0;
1732
1733	audit_buffer_cache = KMEM_CACHE(audit_buffer, SLAB_PANIC);
1734
1735	skb_queue_head_init(&audit_queue);
1736	skb_queue_head_init(&audit_retry_queue);
1737	skb_queue_head_init(&audit_hold_queue);
1738
1739	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1740		INIT_LIST_HEAD(&audit_inode_hash[i]);
1741
1742	mutex_init(&audit_cmd_mutex.lock);
1743	audit_cmd_mutex.owner = NULL;
1744
1745	pr_info("initializing netlink subsys (%s)\n",
1746		str_enabled_disabled(audit_default));
1747	register_pernet_subsys(&audit_net_ops);
1748
1749	audit_initialized = AUDIT_INITIALIZED;
1750
1751	kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1752	if (IS_ERR(kauditd_task)) {
1753		int err = PTR_ERR(kauditd_task);
1754		panic("audit: failed to start the kauditd thread (%d)\n", err);
1755	}
1756
1757	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1758		"state=initialized audit_enabled=%u res=1",
1759		 audit_enabled);
1760
1761	return 0;
1762}
1763postcore_initcall(audit_init);
1764
1765/*
1766 * Process kernel command-line parameter at boot time.
1767 * audit={0|off} or audit={1|on}.
1768 */
1769static int __init audit_enable(char *str)
1770{
1771	if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1772		audit_default = AUDIT_OFF;
1773	else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1774		audit_default = AUDIT_ON;
1775	else {
1776		pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1777		audit_default = AUDIT_ON;
1778	}
1779
1780	if (audit_default == AUDIT_OFF)
1781		audit_initialized = AUDIT_DISABLED;
1782	if (audit_set_enabled(audit_default))
1783		pr_err("audit: error setting audit state (%d)\n",
1784		       audit_default);
1785
1786	pr_info("%s\n", audit_default ?
1787		"enabled (after initialization)" : "disabled (until reboot)");
1788
1789	return 1;
1790}
1791__setup("audit=", audit_enable);
1792
1793/* Process kernel command-line parameter at boot time.
1794 * audit_backlog_limit=<n> */
1795static int __init audit_backlog_limit_set(char *str)
1796{
1797	u32 audit_backlog_limit_arg;
1798
1799	pr_info("audit_backlog_limit: ");
1800	if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1801		pr_cont("using default of %u, unable to parse %s\n",
1802			audit_backlog_limit, str);
1803		return 1;
1804	}
1805
1806	audit_backlog_limit = audit_backlog_limit_arg;
1807	pr_cont("%d\n", audit_backlog_limit);
1808
1809	return 1;
1810}
1811__setup("audit_backlog_limit=", audit_backlog_limit_set);
1812
1813static void audit_buffer_free(struct audit_buffer *ab)
1814{
1815	struct sk_buff *skb;
1816
1817	if (!ab)
1818		return;
1819
1820	while ((skb = skb_dequeue(&ab->skb_list)))
1821		kfree_skb(skb);
1822	kmem_cache_free(audit_buffer_cache, ab);
1823}
1824
1825static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1826					       gfp_t gfp_mask, int type)
1827{
1828	struct audit_buffer *ab;
1829
1830	ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1831	if (!ab)
1832		return NULL;
1833
1834	skb_queue_head_init(&ab->skb_list);
1835
1836	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1837	if (!ab->skb)
1838		goto err;
1839
1840	skb_queue_tail(&ab->skb_list, ab->skb);
1841
1842	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1843		goto err;
1844
1845	ab->ctx = ctx;
1846	ab->gfp_mask = gfp_mask;
1847
1848	return ab;
1849
1850err:
1851	audit_buffer_free(ab);
1852	return NULL;
1853}
1854
1855/**
1856 * audit_serial - compute a serial number for the audit record
1857 *
1858 * Compute a serial number for the audit record.  Audit records are
1859 * written to user-space as soon as they are generated, so a complete
1860 * audit record may be written in several pieces.  The timestamp of the
1861 * record and this serial number are used by the user-space tools to
1862 * determine which pieces belong to the same audit record.  The
1863 * (timestamp,serial) tuple is unique for each syscall and is live from
1864 * syscall entry to syscall exit.
1865 *
1866 * NOTE: Another possibility is to store the formatted records off the
1867 * audit context (for those records that have a context), and emit them
1868 * all at syscall exit.  However, this could delay the reporting of
1869 * significant errors until syscall exit (or never, if the system
1870 * halts).
1871 */
1872unsigned int audit_serial(void)
1873{
1874	static atomic_t serial = ATOMIC_INIT(0);
1875
1876	return atomic_inc_return(&serial);
1877}
1878
1879static inline void audit_get_stamp(struct audit_context *ctx,
1880				   struct audit_stamp *stamp)
1881{
1882	if (!ctx || !auditsc_get_stamp(ctx, stamp)) {
1883		ktime_get_coarse_real_ts64(&stamp->ctime);
1884		stamp->serial = audit_serial();
1885	}
1886}
1887
1888/**
1889 * audit_log_start - obtain an audit buffer
1890 * @ctx: audit_context (may be NULL)
1891 * @gfp_mask: type of allocation
1892 * @type: audit message type
1893 *
1894 * Returns audit_buffer pointer on success or NULL on error.
1895 *
1896 * Obtain an audit buffer.  This routine does locking to obtain the
1897 * audit buffer, but then no locking is required for calls to
1898 * audit_log_*format.  If the task (ctx) is a task that is currently in a
1899 * syscall, then the syscall is marked as auditable and an audit record
1900 * will be written at syscall exit.  If there is no associated task, then
1901 * task context (ctx) should be NULL.
1902 */
1903struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1904				     int type)
1905{
1906	struct audit_buffer *ab;
1907
1908	if (audit_initialized != AUDIT_INITIALIZED)
1909		return NULL;
1910
1911	if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1912		return NULL;
1913
1914	/* NOTE: don't ever fail/sleep on these two conditions:
1915	 * 1. auditd generated record - since we need auditd to drain the
1916	 *    queue; also, when we are checking for auditd, compare PIDs using
1917	 *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1918	 *    using a PID anchored in the caller's namespace
1919	 * 2. generator holding the audit_cmd_mutex - we don't want to block
1920	 *    while holding the mutex, although we do penalize the sender
1921	 *    later in audit_receive() when it is safe to block
1922	 */
1923	if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1924		long stime = audit_backlog_wait_time;
1925
1926		while (audit_backlog_limit &&
1927		       (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1928			/* wake kauditd to try and flush the queue */
1929			wake_up_interruptible(&kauditd_wait);
1930
1931			/* sleep if we are allowed and we haven't exhausted our
1932			 * backlog wait limit */
1933			if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1934				long rtime = stime;
1935
1936				DECLARE_WAITQUEUE(wait, current);
1937
1938				add_wait_queue_exclusive(&audit_backlog_wait,
1939							 &wait);
1940				set_current_state(TASK_UNINTERRUPTIBLE);
1941				stime = schedule_timeout(rtime);
1942				atomic_add(rtime - stime, &audit_backlog_wait_time_actual);
1943				remove_wait_queue(&audit_backlog_wait, &wait);
1944			} else {
1945				if (audit_rate_check() && printk_ratelimit())
1946					pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1947						skb_queue_len(&audit_queue),
1948						audit_backlog_limit);
1949				audit_log_lost("backlog limit exceeded");
1950				return NULL;
1951			}
1952		}
1953	}
1954
1955	ab = audit_buffer_alloc(ctx, gfp_mask, type);
1956	if (!ab) {
1957		audit_log_lost("out of memory in audit_log_start");
1958		return NULL;
1959	}
1960
1961	audit_get_stamp(ab->ctx, &ab->stamp);
1962	/* cancel dummy context to enable supporting records */
1963	if (ctx)
1964		ctx->dummy = 0;
1965	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1966			 (unsigned long long)ab->stamp.ctime.tv_sec,
1967			 ab->stamp.ctime.tv_nsec/1000000,
1968			 ab->stamp.serial);
1969
1970	return ab;
1971}
1972
1973/**
1974 * audit_expand - expand skb in the audit buffer
1975 * @ab: audit_buffer
1976 * @extra: space to add at tail of the skb
1977 *
1978 * Returns 0 (no space) on failed expansion, or available space if
1979 * successful.
1980 */
1981static inline int audit_expand(struct audit_buffer *ab, int extra)
1982{
1983	struct sk_buff *skb = ab->skb;
1984	int oldtail = skb_tailroom(skb);
1985	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1986	int newtail = skb_tailroom(skb);
1987
1988	if (ret < 0) {
1989		audit_log_lost("out of memory in audit_expand");
1990		return 0;
1991	}
1992
1993	skb->truesize += newtail - oldtail;
1994	return newtail;
1995}
1996
1997/*
1998 * Format an audit message into the audit buffer.  If there isn't enough
1999 * room in the audit buffer, more room will be allocated and vsnprint
2000 * will be called a second time.  Currently, we assume that a printk
2001 * can't format message larger than 1024 bytes, so we don't either.
2002 */
2003static __printf(2, 0)
2004void audit_log_vformat(struct audit_buffer *ab, const char *fmt, va_list args)
2005{
2006	int len, avail;
2007	struct sk_buff *skb;
2008	va_list args2;
2009
2010	if (!ab)
2011		return;
2012
2013	BUG_ON(!ab->skb);
2014	skb = ab->skb;
2015	avail = skb_tailroom(skb);
2016	if (avail == 0) {
2017		avail = audit_expand(ab, AUDIT_BUFSIZ);
2018		if (!avail)
2019			goto out;
2020	}
2021	va_copy(args2, args);
2022	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
2023	if (len >= avail) {
2024		/* The printk buffer is 1024 bytes long, so if we get
2025		 * here and AUDIT_BUFSIZ is at least 1024, then we can
2026		 * log everything that printk could have logged. */
2027		avail = audit_expand(ab,
2028			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
2029		if (!avail)
2030			goto out_va_end;
2031		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
2032	}
2033	if (len > 0)
2034		skb_put(skb, len);
2035out_va_end:
2036	va_end(args2);
2037out:
2038	return;
2039}
2040
2041/**
2042 * audit_log_format - format a message into the audit buffer.
2043 * @ab: audit_buffer
2044 * @fmt: format string
2045 * @...: optional parameters matching @fmt string
2046 *
2047 * All the work is done in audit_log_vformat.
2048 */
2049void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
2050{
2051	va_list args;
2052
2053	if (!ab)
2054		return;
2055	va_start(args, fmt);
2056	audit_log_vformat(ab, fmt, args);
2057	va_end(args);
2058}
2059
2060/**
2061 * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
2062 * @ab: the audit_buffer
2063 * @buf: buffer to convert to hex
2064 * @len: length of @buf to be converted
2065 *
2066 * No return value; failure to expand is silently ignored.
2067 *
2068 * This function will take the passed buf and convert it into a string of
2069 * ascii hex digits. The new string is placed onto the skb.
2070 */
2071void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
2072		size_t len)
2073{
2074	int i, avail, new_len;
2075	unsigned char *ptr;
2076	struct sk_buff *skb;
2077
2078	if (!ab)
2079		return;
2080
2081	BUG_ON(!ab->skb);
2082	skb = ab->skb;
2083	avail = skb_tailroom(skb);
2084	new_len = len<<1;
2085	if (new_len >= avail) {
2086		/* Round the buffer request up to the next multiple */
2087		new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
2088		avail = audit_expand(ab, new_len);
2089		if (!avail)
2090			return;
2091	}
2092
2093	ptr = skb_tail_pointer(skb);
2094	for (i = 0; i < len; i++)
2095		ptr = hex_byte_pack_upper(ptr, buf[i]);
2096	*ptr = 0;
2097	skb_put(skb, len << 1); /* new string is twice the old string */
2098}
2099
2100/*
2101 * Format a string of no more than slen characters into the audit buffer,
2102 * enclosed in quote marks.
2103 */
2104void audit_log_n_string(struct audit_buffer *ab, const char *string,
2105			size_t slen)
2106{
2107	int avail, new_len;
2108	unsigned char *ptr;
2109	struct sk_buff *skb;
2110
2111	if (!ab)
2112		return;
2113
2114	BUG_ON(!ab->skb);
2115	skb = ab->skb;
2116	avail = skb_tailroom(skb);
2117	new_len = slen + 3;	/* enclosing quotes + null terminator */
2118	if (new_len > avail) {
2119		avail = audit_expand(ab, new_len);
2120		if (!avail)
2121			return;
2122	}
2123	ptr = skb_tail_pointer(skb);
2124	*ptr++ = '"';
2125	memcpy(ptr, string, slen);
2126	ptr += slen;
2127	*ptr++ = '"';
2128	*ptr = 0;
2129	skb_put(skb, slen + 2);	/* don't include null terminator */
2130}
2131
2132/**
2133 * audit_string_contains_control - does a string need to be logged in hex
2134 * @string: string to be checked
2135 * @len: max length of the string to check
2136 */
2137bool audit_string_contains_control(const char *string, size_t len)
2138{
2139	const unsigned char *p;
2140	for (p = string; p < (const unsigned char *)string + len; p++) {
2141		if (*p == '"' || *p < 0x21 || *p > 0x7e)
2142			return true;
2143	}
2144	return false;
2145}
2146
2147/**
2148 * audit_log_n_untrustedstring - log a string that may contain random characters
2149 * @ab: audit_buffer
2150 * @string: string to be logged
2151 * @len: length of string (not including trailing null)
2152 *
2153 * This code will escape a string that is passed to it if the string
2154 * contains a control character, unprintable character, double quote mark,
2155 * or a space. Unescaped strings will start and end with a double quote mark.
2156 * Strings that are escaped are printed in hex (2 digits per char).
2157 *
2158 * The caller specifies the number of characters in the string to log, which may
2159 * or may not be the entire string.
2160 */
2161void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2162				 size_t len)
2163{
2164	if (audit_string_contains_control(string, len))
2165		audit_log_n_hex(ab, string, len);
2166	else
2167		audit_log_n_string(ab, string, len);
2168}
2169
2170/**
2171 * audit_log_untrustedstring - log a string that may contain random characters
2172 * @ab: audit_buffer
2173 * @string: string to be logged
2174 *
2175 * Same as audit_log_n_untrustedstring(), except that strlen is used to
2176 * determine string length.
2177 */
2178void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2179{
2180	audit_log_n_untrustedstring(ab, string, strlen(string));
2181}
2182
2183/* This is a helper-function to print the escaped d_path */
2184void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2185		      const struct path *path)
2186{
2187	char *p, *pathname;
2188
2189	if (prefix)
2190		audit_log_format(ab, "%s", prefix);
2191
2192	/* We will allow 11 spaces for ' (deleted)' to be appended */
2193	pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2194	if (!pathname) {
2195		audit_log_format(ab, "\"<no_memory>\"");
2196		return;
2197	}
2198	p = d_path(path, pathname, PATH_MAX+11);
2199	if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2200		/* FIXME: can we save some information here? */
2201		audit_log_format(ab, "\"<too_long>\"");
2202	} else
2203		audit_log_untrustedstring(ab, p);
2204	kfree(pathname);
2205}
2206
2207void audit_log_session_info(struct audit_buffer *ab)
2208{
2209	unsigned int sessionid = audit_get_sessionid(current);
2210	uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2211
2212	audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2213}
2214
2215void audit_log_key(struct audit_buffer *ab, char *key)
2216{
2217	audit_log_format(ab, " key=");
2218	if (key)
2219		audit_log_untrustedstring(ab, key);
2220	else
2221		audit_log_format(ab, "(null)");
2222}
2223
2224/**
2225 * audit_buffer_aux_new - Add an aux record buffer to the skb list
2226 * @ab: audit_buffer
2227 * @type: message type
2228 *
2229 * Aux records are allocated and added to the skb list of
2230 * the "main" record. The ab->skb is reset to point to the
2231 * aux record on its creation. When the aux record in complete
2232 * ab->skb has to be reset to point to the "main" record.
2233 * This allows the audit_log_ functions to be ignorant of
2234 * which kind of record it is logging to. It also avoids adding
2235 * special data for aux records.
2236 *
2237 * On success ab->skb will point to the new aux record.
2238 * Returns 0 on success, -ENOMEM should allocation fail.
2239 */
2240static int audit_buffer_aux_new(struct audit_buffer *ab, int type)
2241{
2242	WARN_ON(ab->skb != skb_peek(&ab->skb_list));
2243
2244	ab->skb = nlmsg_new(AUDIT_BUFSIZ, ab->gfp_mask);
2245	if (!ab->skb)
2246		goto err;
2247	if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
2248		goto err;
2249	skb_queue_tail(&ab->skb_list, ab->skb);
2250
2251	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
2252			 (unsigned long long)ab->stamp.ctime.tv_sec,
2253			 ab->stamp.ctime.tv_nsec/1000000,
2254			 ab->stamp.serial);
2255
2256	return 0;
2257
2258err:
2259	kfree_skb(ab->skb);
2260	ab->skb = skb_peek(&ab->skb_list);
2261	return -ENOMEM;
2262}
2263
2264/**
2265 * audit_buffer_aux_end - Switch back to the "main" record from an aux record
2266 * @ab: audit_buffer
2267 *
2268 * Restores the "main" audit record to ab->skb.
2269 */
2270static void audit_buffer_aux_end(struct audit_buffer *ab)
2271{
2272	ab->skb = skb_peek(&ab->skb_list);
2273}
2274
2275/**
2276 * audit_log_subj_ctx - Add LSM subject information
2277 * @ab: audit_buffer
2278 * @prop: LSM subject properties.
2279 *
2280 * Add a subj= field and, if necessary, a AUDIT_MAC_TASK_CONTEXTS record.
2281 */
2282int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
2283{
2284	struct lsm_context ctx;
2285	char *space = "";
2286	int error;
2287	int i;
2288
2289	security_current_getlsmprop_subj(prop);
2290	if (!lsmprop_is_set(prop))
2291		return 0;
2292
2293	if (audit_subj_secctx_cnt < 2) {
2294		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
2295		if (error < 0) {
2296			if (error != -EINVAL)
2297				goto error_path;
2298			return 0;
2299		}
2300		audit_log_format(ab, " subj=%s", ctx.context);
2301		security_release_secctx(&ctx);
2302		return 0;
2303	}
2304	/* Multiple LSMs provide contexts. Include an aux record. */
2305	audit_log_format(ab, " subj=?");
2306	error = audit_buffer_aux_new(ab, AUDIT_MAC_TASK_CONTEXTS);
2307	if (error)
2308		goto error_path;
2309
2310	for (i = 0; i < audit_subj_secctx_cnt; i++) {
2311		error = security_lsmprop_to_secctx(prop, &ctx,
2312						   audit_subj_lsms[i]->id);
2313		if (error < 0) {
2314			/*
2315			 * Don't print anything. An LSM like BPF could
2316			 * claim to support contexts, but only do so under
2317			 * certain conditions.
2318			 */
2319			if (error == -EOPNOTSUPP)
2320				continue;
2321			if (error != -EINVAL)
2322				audit_panic("error in audit_log_subj_ctx");
2323		} else {
2324			audit_log_format(ab, "%ssubj_%s=%s", space,
2325					 audit_subj_lsms[i]->name, ctx.context);
2326			space = " ";
2327			security_release_secctx(&ctx);
2328		}
2329	}
2330	audit_buffer_aux_end(ab);
2331	return 0;
2332
2333error_path:
2334	audit_panic("error in audit_log_subj_ctx");
2335	return error;
2336}
2337EXPORT_SYMBOL(audit_log_subj_ctx);
2338
2339int audit_log_task_context(struct audit_buffer *ab)
2340{
2341	struct lsm_prop prop;
2342
2343	security_current_getlsmprop_subj(&prop);
2344	return audit_log_subj_ctx(ab, &prop);
2345}
2346EXPORT_SYMBOL(audit_log_task_context);
2347
2348int audit_log_obj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
2349{
2350	int i;
2351	int rc;
2352	int error = 0;
2353	char *space = "";
2354	struct lsm_context ctx;
2355
2356	if (audit_obj_secctx_cnt < 2) {
2357		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
2358		if (error < 0) {
2359			if (error != -EINVAL)
2360				goto error_path;
2361			return error;
2362		}
2363		audit_log_format(ab, " obj=%s", ctx.context);
2364		security_release_secctx(&ctx);
2365		return 0;
2366	}
2367	audit_log_format(ab, " obj=?");
2368	error = audit_buffer_aux_new(ab, AUDIT_MAC_OBJ_CONTEXTS);
2369	if (error)
2370		goto error_path;
2371
2372	for (i = 0; i < audit_obj_secctx_cnt; i++) {
2373		rc = security_lsmprop_to_secctx(prop, &ctx,
2374						audit_obj_lsms[i]->id);
2375		if (rc < 0) {
2376			audit_log_format(ab, "%sobj_%s=?", space,
2377					 audit_obj_lsms[i]->name);
2378			if (rc != -EINVAL)
2379				audit_panic("error in audit_log_obj_ctx");
2380			error = rc;
2381		} else {
2382			audit_log_format(ab, "%sobj_%s=%s", space,
2383					 audit_obj_lsms[i]->name, ctx.context);
2384			security_release_secctx(&ctx);
2385		}
2386		space = " ";
2387	}
2388
2389	audit_buffer_aux_end(ab);
2390	return error;
2391
2392error_path:
2393	audit_panic("error in audit_log_obj_ctx");
2394	return error;
2395}
2396
2397void audit_log_d_path_exe(struct audit_buffer *ab,
2398			  struct mm_struct *mm)
2399{
2400	struct file *exe_file;
2401
2402	if (!mm)
2403		goto out_null;
2404
2405	exe_file = get_mm_exe_file(mm);
2406	if (!exe_file)
2407		goto out_null;
2408
2409	audit_log_d_path(ab, " exe=", &exe_file->f_path);
2410	fput(exe_file);
2411	return;
2412out_null:
2413	audit_log_format(ab, " exe=(null)");
2414}
2415
2416struct tty_struct *audit_get_tty(void)
2417{
2418	struct tty_struct *tty = NULL;
2419	unsigned long flags;
2420
2421	spin_lock_irqsave(&current->sighand->siglock, flags);
2422	if (current->signal)
2423		tty = tty_kref_get(current->signal->tty);
2424	spin_unlock_irqrestore(&current->sighand->siglock, flags);
2425	return tty;
2426}
2427
2428void audit_put_tty(struct tty_struct *tty)
2429{
2430	tty_kref_put(tty);
2431}
2432
2433void audit_log_task_info(struct audit_buffer *ab)
2434{
2435	const struct cred *cred;
2436	char comm[sizeof(current->comm)];
2437	struct tty_struct *tty;
2438
2439	if (!ab)
2440		return;
2441
2442	cred = current_cred();
2443	tty = audit_get_tty();
2444	audit_log_format(ab,
2445			 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2446			 " euid=%u suid=%u fsuid=%u"
2447			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2448			 task_ppid_nr(current),
2449			 task_tgid_nr(current),
2450			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
2451			 from_kuid(&init_user_ns, cred->uid),
2452			 from_kgid(&init_user_ns, cred->gid),
2453			 from_kuid(&init_user_ns, cred->euid),
2454			 from_kuid(&init_user_ns, cred->suid),
2455			 from_kuid(&init_user_ns, cred->fsuid),
2456			 from_kgid(&init_user_ns, cred->egid),
2457			 from_kgid(&init_user_ns, cred->sgid),
2458			 from_kgid(&init_user_ns, cred->fsgid),
2459			 tty ? tty_name(tty) : "(none)",
2460			 audit_get_sessionid(current));
2461	audit_put_tty(tty);
2462	audit_log_format(ab, " comm=");
2463	audit_log_untrustedstring(ab, get_task_comm(comm, current));
2464	audit_log_d_path_exe(ab, current->mm);
2465	audit_log_task_context(ab);
2466}
2467EXPORT_SYMBOL(audit_log_task_info);
2468
2469/**
2470 * audit_log_path_denied - report a path restriction denial
2471 * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc)
2472 * @operation: specific operation name
2473 */
2474void audit_log_path_denied(int type, const char *operation)
2475{
2476	struct audit_buffer *ab;
2477
2478	if (!audit_enabled)
2479		return;
2480
2481	/* Generate log with subject, operation, outcome. */
2482	ab = audit_log_start(audit_context(), GFP_KERNEL, type);
2483	if (!ab)
2484		return;
2485	audit_log_format(ab, "op=%s", operation);
2486	audit_log_task_info(ab);
2487	audit_log_format(ab, " res=0");
2488	audit_log_end(ab);
2489}
2490
2491/* global counter which is incremented every time something logs in */
2492static atomic_t session_id = ATOMIC_INIT(0);
2493
2494static int audit_set_loginuid_perm(kuid_t loginuid)
2495{
2496	/* if we are unset, we don't need privs */
2497	if (!audit_loginuid_set(current))
2498		return 0;
2499	/* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2500	if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2501		return -EPERM;
2502	/* it is set, you need permission */
2503	if (!capable(CAP_AUDIT_CONTROL))
2504		return -EPERM;
2505	/* reject if this is not an unset and we don't allow that */
2506	if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2507				 && uid_valid(loginuid))
2508		return -EPERM;
2509	return 0;
2510}
2511
2512static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2513				   unsigned int oldsessionid,
2514				   unsigned int sessionid, int rc)
2515{
2516	struct audit_buffer *ab;
2517	uid_t uid, oldloginuid, loginuid;
2518	struct tty_struct *tty;
2519
2520	if (!audit_enabled)
2521		return;
2522
2523	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2524	if (!ab)
2525		return;
2526
2527	uid = from_kuid(&init_user_ns, task_uid(current));
2528	oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2529	loginuid = from_kuid(&init_user_ns, kloginuid);
2530	tty = audit_get_tty();
2531
2532	audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2533	audit_log_task_context(ab);
2534	audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2535			 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2536			 oldsessionid, sessionid, !rc);
2537	audit_put_tty(tty);
2538	audit_log_end(ab);
2539}
2540
2541/**
2542 * audit_set_loginuid - set current task's loginuid
2543 * @loginuid: loginuid value
2544 *
2545 * Returns 0.
2546 *
2547 * Called (set) from fs/proc/base.c::proc_loginuid_write().
2548 */
2549int audit_set_loginuid(kuid_t loginuid)
2550{
2551	unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2552	kuid_t oldloginuid;
2553	int rc;
2554
2555	oldloginuid = audit_get_loginuid(current);
2556	oldsessionid = audit_get_sessionid(current);
2557
2558	rc = audit_set_loginuid_perm(loginuid);
2559	if (rc)
2560		goto out;
2561
2562	/* are we setting or clearing? */
2563	if (uid_valid(loginuid)) {
2564		sessionid = (unsigned int)atomic_inc_return(&session_id);
2565		if (unlikely(sessionid == AUDIT_SID_UNSET))
2566			sessionid = (unsigned int)atomic_inc_return(&session_id);
2567	}
2568
2569	current->sessionid = sessionid;
2570	current->loginuid = loginuid;
2571out:
2572	audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2573	return rc;
2574}
2575
2576/**
2577 * audit_signal_info - record signal info for shutting down audit subsystem
2578 * @sig: signal value
2579 * @t: task being signaled
2580 *
2581 * If the audit subsystem is being terminated, record the task (pid)
2582 * and uid that is doing that.
2583 */
2584int audit_signal_info(int sig, struct task_struct *t)
2585{
2586	kuid_t uid = current_uid(), auid;
2587
2588	if (auditd_test_task(t) &&
2589	    (sig == SIGTERM || sig == SIGHUP ||
2590	     sig == SIGUSR1 || sig == SIGUSR2)) {
2591		audit_sig_pid = task_tgid_nr(current);
2592		auid = audit_get_loginuid(current);
2593		if (uid_valid(auid))
2594			audit_sig_uid = auid;
2595		else
2596			audit_sig_uid = uid;
2597		security_current_getlsmprop_subj(&audit_sig_lsm);
2598	}
2599
2600	return audit_signal_info_syscall(t);
2601}
2602
2603/**
2604 * __audit_log_end - enqueue one audit record
2605 * @skb: the buffer to send
2606 */
2607static void __audit_log_end(struct sk_buff *skb)
2608{
2609	struct nlmsghdr *nlh;
2610
2611	if (audit_rate_check()) {
2612		/* setup the netlink header, see the comments in
2613		 * kauditd_send_multicast_skb() for length quirks */
2614		nlh = nlmsg_hdr(skb);
2615		nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2616
2617		/* queue the netlink packet */
2618		skb_queue_tail(&audit_queue, skb);
2619	} else {
2620		audit_log_lost("rate limit exceeded");
2621		kfree_skb(skb);
2622	}
2623}
2624
2625/**
2626 * audit_log_end - end one audit record
2627 * @ab: the audit_buffer
2628 *
2629 * We can not do a netlink send inside an irq context because it blocks (last
2630 * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2631 * queue and a kthread is scheduled to remove them from the queue outside the
2632 * irq context.  May be called in any context.
2633 */
2634void audit_log_end(struct audit_buffer *ab)
2635{
2636	struct sk_buff *skb;
2637
2638	if (!ab)
2639		return;
2640
2641	while ((skb = skb_dequeue(&ab->skb_list)))
2642		__audit_log_end(skb);
2643
2644	/* poke the kauditd thread */
2645	wake_up_interruptible(&kauditd_wait);
2646
2647	audit_buffer_free(ab);
2648}
2649
2650/**
2651 * audit_log - Log an audit record
2652 * @ctx: audit context
2653 * @gfp_mask: type of allocation
2654 * @type: audit message type
2655 * @fmt: format string to use
2656 * @...: variable parameters matching the format string
2657 *
2658 * This is a convenience function that calls audit_log_start,
2659 * audit_log_vformat, and audit_log_end.  It may be called
2660 * in any context.
2661 */
2662void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2663	       const char *fmt, ...)
2664{
2665	struct audit_buffer *ab;
2666	va_list args;
2667
2668	ab = audit_log_start(ctx, gfp_mask, type);
2669	if (ab) {
2670		va_start(args, fmt);
2671		audit_log_vformat(ab, fmt, args);
2672		va_end(args);
2673		audit_log_end(ab);
2674	}
2675}
2676
2677EXPORT_SYMBOL(audit_log_start);
2678EXPORT_SYMBOL(audit_log_end);
2679EXPORT_SYMBOL(audit_log_format);
2680EXPORT_SYMBOL(audit_log);