1/* audit.c -- Auditing support
   2 * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
   3 * System-call specific features have moved to auditsc.c
   4 *
   5 * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
   6 * All Rights Reserved.
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as published by
  10 * the Free Software Foundation; either version 2 of the License, or
  11 * (at your option) any later version.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 *
  22 * Written by Rickard E. (Rik) Faith <faith@redhat.com>
  23 *
  24 * Goals: 1) Integrate fully with Security Modules.
  25 *	  2) Minimal run-time overhead:
  26 *	     a) Minimal when syscall auditing is disabled (audit_enable=0).
  27 *	     b) Small when syscall auditing is enabled and no audit record
  28 *		is generated (defer as much work as possible to record
  29 *		generation time):
  30 *		i) context is allocated,
  31 *		ii) names from getname are stored without a copy, and
  32 *		iii) inode information stored from path_lookup.
  33 *	  3) Ability to disable syscall auditing at boot time (audit=0).
  34 *	  4) Usable by other parts of the kernel (if audit_log* is called,
  35 *	     then a syscall record will be generated automatically for the
  36 *	     current syscall).
  37 *	  5) Netlink interface to user-space.
  38 *	  6) Support low-overhead kernel-based filtering to minimize the
  39 *	     information that must be passed to user-space.
  40 *
  41 * Example user-space utilities: http://people.redhat.com/sgrubb/audit/
  42 */
  43
  44#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  45
  46#include <linux/file.h>
  47#include <linux/init.h>
  48#include <linux/types.h>
  49#include <linux/atomic.h>
  50#include <linux/mm.h>
  51#include <linux/export.h>
  52#include <linux/slab.h>
  53#include <linux/err.h>
  54#include <linux/kthread.h>
  55#include <linux/kernel.h>
  56#include <linux/syscalls.h>
  57
  58#include <linux/audit.h>
  59
  60#include <net/sock.h>
  61#include <net/netlink.h>
  62#include <linux/skbuff.h>
  63#ifdef CONFIG_SECURITY
  64#include <linux/security.h>
  65#endif
 
  66#include <linux/freezer.h>
  67#include <linux/tty.h>
  68#include <linux/pid_namespace.h>
  69#include <net/netns/generic.h>
  70
  71#include "audit.h"
  72
  73/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
  74 * (Initialization happens after skb_init is called.) */
  75#define AUDIT_DISABLED		-1
  76#define AUDIT_UNINITIALIZED	0
  77#define AUDIT_INITIALIZED	1
  78static int	audit_initialized;
  79
  80#define AUDIT_OFF	0
  81#define AUDIT_ON	1
  82#define AUDIT_LOCKED	2
  83u32		audit_enabled;
  84u32		audit_ever_enabled;
  85
  86EXPORT_SYMBOL_GPL(audit_enabled);
  87
  88/* Default state when kernel boots without any parameters. */
  89static u32	audit_default;
  90
  91/* If auditing cannot proceed, audit_failure selects what happens. */
  92static u32	audit_failure = AUDIT_FAIL_PRINTK;
  93
  94/*
  95 * If audit records are to be written to the netlink socket, audit_pid
  96 * contains the pid of the auditd process and audit_nlk_portid contains
  97 * the portid to use to send netlink messages to that process.
  98 */
  99int		audit_pid;
 100static __u32	audit_nlk_portid;
 101
 102/* If audit_rate_limit is non-zero, limit the rate of sending audit records
 103 * to that number per second.  This prevents DoS attacks, but results in
 104 * audit records being dropped. */
 105static u32	audit_rate_limit;
 106
 107/* Number of outstanding audit_buffers allowed.
 108 * When set to zero, this means unlimited. */
 109static u32	audit_backlog_limit = 64;
 110#define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
 111static u32	audit_backlog_wait_time_master = AUDIT_BACKLOG_WAIT_TIME;
 112static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
 113
 114/* The identity of the user shutting down the audit system. */
 115kuid_t		audit_sig_uid = INVALID_UID;
 116pid_t		audit_sig_pid = -1;
 117u32		audit_sig_sid = 0;
 118
 119/* Records can be lost in several ways:
 120   0) [suppressed in audit_alloc]
 121   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
 122   2) out of memory in audit_log_move [alloc_skb]
 123   3) suppressed due to audit_rate_limit
 124   4) suppressed due to audit_backlog_limit
 125*/
 126static atomic_t    audit_lost = ATOMIC_INIT(0);
 127
 128/* The netlink socket. */
 129static struct sock *audit_sock;
 130static int audit_net_id;
 131
 132/* Hash for inode-based rules */
 133struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 134
 135/* The audit_freelist is a list of pre-allocated audit buffers (if more
 136 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
 137 * being placed on the freelist). */
 138static DEFINE_SPINLOCK(audit_freelist_lock);
 139static int	   audit_freelist_count;
 140static LIST_HEAD(audit_freelist);
 141
 142static struct sk_buff_head audit_skb_queue;
 143/* queue of skbs to send to auditd when/if it comes back */
 144static struct sk_buff_head audit_skb_hold_queue;
 145static struct task_struct *kauditd_task;
 146static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 147static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 148
 149static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
 150				   .mask = -1,
 151				   .features = 0,
 152				   .lock = 0,};
 153
 154static char *audit_feature_names[2] = {
 155	"only_unset_loginuid",
 156	"loginuid_immutable",
 157};
 158
 159
 160/* Serialize requests from userspace. */
 161DEFINE_MUTEX(audit_cmd_mutex);
 162
 163/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 164 * audit records.  Since printk uses a 1024 byte buffer, this buffer
 165 * should be at least that large. */
 166#define AUDIT_BUFSIZ 1024
 167
 168/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
 169 * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
 170#define AUDIT_MAXFREE  (2*NR_CPUS)
 171
 172/* The audit_buffer is used when formatting an audit record.  The caller
 173 * locks briefly to get the record off the freelist or to allocate the
 174 * buffer, and locks briefly to send the buffer to the netlink layer or
 175 * to place it on a transmit queue.  Multiple audit_buffers can be in
 176 * use simultaneously. */
 177struct audit_buffer {
 178	struct list_head     list;
 179	struct sk_buff       *skb;	/* formatted skb ready to send */
 180	struct audit_context *ctx;	/* NULL or associated context */
 181	gfp_t		     gfp_mask;
 182};
 183
 184struct audit_reply {
 185	__u32 portid;
 186	struct net *net;
 187	struct sk_buff *skb;
 188};
 189
 190static void audit_set_portid(struct audit_buffer *ab, __u32 portid)
 191{
 192	if (ab) {
 193		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
 194		nlh->nlmsg_pid = portid;
 195	}
 196}
 197
 198void audit_panic(const char *message)
 199{
 200	switch (audit_failure) {
 
 201	case AUDIT_FAIL_SILENT:
 202		break;
 203	case AUDIT_FAIL_PRINTK:
 204		if (printk_ratelimit())
 205			pr_err("%s\n", message);
 206		break;
 207	case AUDIT_FAIL_PANIC:
 208		/* test audit_pid since printk is always losey, why bother? */
 209		if (audit_pid)
 210			panic("audit: %s\n", message);
 211		break;
 212	}
 213}
 214
 215static inline int audit_rate_check(void)
 216{
 217	static unsigned long	last_check = 0;
 218	static int		messages   = 0;
 219	static DEFINE_SPINLOCK(lock);
 220	unsigned long		flags;
 221	unsigned long		now;
 222	unsigned long		elapsed;
 223	int			retval	   = 0;
 224
 225	if (!audit_rate_limit) return 1;
 226
 227	spin_lock_irqsave(&lock, flags);
 228	if (++messages < audit_rate_limit) {
 229		retval = 1;
 230	} else {
 231		now     = jiffies;
 232		elapsed = now - last_check;
 233		if (elapsed > HZ) {
 234			last_check = now;
 235			messages   = 0;
 236			retval     = 1;
 237		}
 238	}
 239	spin_unlock_irqrestore(&lock, flags);
 240
 241	return retval;
 242}
 243
 244/**
 245 * audit_log_lost - conditionally log lost audit message event
 246 * @message: the message stating reason for lost audit message
 247 *
 248 * Emit at least 1 message per second, even if audit_rate_check is
 249 * throttling.
 250 * Always increment the lost messages counter.
 251*/
 252void audit_log_lost(const char *message)
 253{
 254	static unsigned long	last_msg = 0;
 255	static DEFINE_SPINLOCK(lock);
 256	unsigned long		flags;
 257	unsigned long		now;
 258	int			print;
 259
 260	atomic_inc(&audit_lost);
 261
 262	print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 263
 264	if (!print) {
 265		spin_lock_irqsave(&lock, flags);
 266		now = jiffies;
 267		if (now - last_msg > HZ) {
 268			print = 1;
 269			last_msg = now;
 270		}
 271		spin_unlock_irqrestore(&lock, flags);
 272	}
 273
 274	if (print) {
 275		if (printk_ratelimit())
 276			pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
 
 
 277				atomic_read(&audit_lost),
 278				audit_rate_limit,
 279				audit_backlog_limit);
 280		audit_panic(message);
 281	}
 282}
 283
 284static int audit_log_config_change(char *function_name, u32 new, u32 old,
 
 285				   int allow_changes)
 286{
 287	struct audit_buffer *ab;
 288	int rc = 0;
 289
 290	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 291	if (unlikely(!ab))
 292		return rc;
 293	audit_log_format(ab, "%s=%u old=%u", function_name, new, old);
 294	audit_log_session_info(ab);
 295	rc = audit_log_task_context(ab);
 296	if (rc)
 297		allow_changes = 0; /* Something weird, deny request */
 
 
 
 
 
 
 
 
 298	audit_log_format(ab, " res=%d", allow_changes);
 299	audit_log_end(ab);
 300	return rc;
 301}
 302
 303static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
 
 
 304{
 305	int allow_changes, rc = 0;
 306	u32 old = *to_change;
 307
 308	/* check if we are locked */
 309	if (audit_enabled == AUDIT_LOCKED)
 310		allow_changes = 0;
 311	else
 312		allow_changes = 1;
 313
 314	if (audit_enabled != AUDIT_OFF) {
 315		rc = audit_log_config_change(function_name, new, old, allow_changes);
 
 316		if (rc)
 317			allow_changes = 0;
 318	}
 319
 320	/* If we are allowed, make the change */
 321	if (allow_changes == 1)
 322		*to_change = new;
 323	/* Not allowed, update reason */
 324	else if (rc == 0)
 325		rc = -EPERM;
 326	return rc;
 327}
 328
 329static int audit_set_rate_limit(u32 limit)
 330{
 331	return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
 332}
 333
 334static int audit_set_backlog_limit(u32 limit)
 335{
 336	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
 
 337}
 338
 339static int audit_set_backlog_wait_time(u32 timeout)
 
 340{
 341	return audit_do_config_change("audit_backlog_wait_time",
 342				      &audit_backlog_wait_time_master, timeout);
 343}
 344
 345static int audit_set_enabled(u32 state)
 346{
 347	int rc;
 348	if (state > AUDIT_LOCKED)
 349		return -EINVAL;
 350
 351	rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
 
 
 352	if (!rc)
 353		audit_ever_enabled |= !!state;
 354
 355	return rc;
 356}
 357
 358static int audit_set_failure(u32 state)
 359{
 360	if (state != AUDIT_FAIL_SILENT
 361	    && state != AUDIT_FAIL_PRINTK
 362	    && state != AUDIT_FAIL_PANIC)
 363		return -EINVAL;
 364
 365	return audit_do_config_change("audit_failure", &audit_failure, state);
 
 366}
 367
 368/*
 369 * Queue skbs to be sent to auditd when/if it comes back.  These skbs should
 370 * already have been sent via prink/syslog and so if these messages are dropped
 371 * it is not a huge concern since we already passed the audit_log_lost()
 372 * notification and stuff.  This is just nice to get audit messages during
 373 * boot before auditd is running or messages generated while auditd is stopped.
 374 * This only holds messages is audit_default is set, aka booting with audit=1
 375 * or building your kernel that way.
 376 */
 377static void audit_hold_skb(struct sk_buff *skb)
 378{
 379	if (audit_default &&
 380	    (!audit_backlog_limit ||
 381	     skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit))
 382		skb_queue_tail(&audit_skb_hold_queue, skb);
 383	else
 384		kfree_skb(skb);
 385}
 386
 387/*
 388 * For one reason or another this nlh isn't getting delivered to the userspace
 389 * audit daemon, just send it to printk.
 390 */
 391static void audit_printk_skb(struct sk_buff *skb)
 392{
 393	struct nlmsghdr *nlh = nlmsg_hdr(skb);
 394	char *data = nlmsg_data(nlh);
 395
 396	if (nlh->nlmsg_type != AUDIT_EOE) {
 397		if (printk_ratelimit())
 398			pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
 399		else
 400			audit_log_lost("printk limit exceeded");
 401	}
 402
 403	audit_hold_skb(skb);
 404}
 405
 406static void kauditd_send_skb(struct sk_buff *skb)
 407{
 408	int err;
 409	int attempts = 0;
 410#define AUDITD_RETRIES 5
 411
 412restart:
 413	/* take a reference in case we can't send it and we want to hold it */
 414	skb_get(skb);
 415	err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
 416	if (err < 0) {
 417		pr_err("netlink_unicast sending to audit_pid=%d returned error: %d\n",
 418		       audit_pid, err);
 419		if (audit_pid) {
 420			if (err == -ECONNREFUSED || err == -EPERM
 421			    || ++attempts >= AUDITD_RETRIES) {
 422				char s[32];
 423
 424				snprintf(s, sizeof(s), "audit_pid=%d reset", audit_pid);
 425				audit_log_lost(s);
 426				audit_pid = 0;
 427				audit_sock = NULL;
 428			} else {
 429				pr_warn("re-scheduling(#%d) write to audit_pid=%d\n",
 430					attempts, audit_pid);
 431				set_current_state(TASK_INTERRUPTIBLE);
 432				schedule();
 433				__set_current_state(TASK_RUNNING);
 434				goto restart;
 435			}
 436		}
 437		/* we might get lucky and get this in the next auditd */
 438		audit_hold_skb(skb);
 439	} else
 440		/* drop the extra reference if sent ok */
 441		consume_skb(skb);
 442}
 443
 444/*
 445 * kauditd_send_multicast_skb - send the skb to multicast userspace listeners
 446 *
 447 * This function doesn't consume an skb as might be expected since it has to
 448 * copy it anyways.
 449 */
 450static void kauditd_send_multicast_skb(struct sk_buff *skb, gfp_t gfp_mask)
 451{
 452	struct sk_buff		*copy;
 453	struct audit_net	*aunet = net_generic(&init_net, audit_net_id);
 454	struct sock		*sock = aunet->nlsk;
 455
 456	if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
 457		return;
 458
 459	/*
 460	 * The seemingly wasteful skb_copy() rather than bumping the refcount
 461	 * using skb_get() is necessary because non-standard mods are made to
 462	 * the skb by the original kaudit unicast socket send routine.  The
 463	 * existing auditd daemon assumes this breakage.  Fixing this would
 464	 * require co-ordinating a change in the established protocol between
 465	 * the kaudit kernel subsystem and the auditd userspace code.  There is
 466	 * no reason for new multicast clients to continue with this
 467	 * non-compliance.
 468	 */
 469	copy = skb_copy(skb, gfp_mask);
 470	if (!copy)
 471		return;
 472
 473	nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, gfp_mask);
 474}
 475
 476/*
 477 * flush_hold_queue - empty the hold queue if auditd appears
 478 *
 479 * If auditd just started, drain the queue of messages already
 480 * sent to syslog/printk.  Remember loss here is ok.  We already
 481 * called audit_log_lost() if it didn't go out normally.  so the
 482 * race between the skb_dequeue and the next check for audit_pid
 483 * doesn't matter.
 484 *
 485 * If you ever find kauditd to be too slow we can get a perf win
 486 * by doing our own locking and keeping better track if there
 487 * are messages in this queue.  I don't see the need now, but
 488 * in 5 years when I want to play with this again I'll see this
 489 * note and still have no friggin idea what i'm thinking today.
 490 */
 491static void flush_hold_queue(void)
 492{
 493	struct sk_buff *skb;
 494
 495	if (!audit_default || !audit_pid)
 496		return;
 497
 498	skb = skb_dequeue(&audit_skb_hold_queue);
 499	if (likely(!skb))
 500		return;
 501
 502	while (skb && audit_pid) {
 503		kauditd_send_skb(skb);
 504		skb = skb_dequeue(&audit_skb_hold_queue);
 505	}
 506
 507	/*
 508	 * if auditd just disappeared but we
 509	 * dequeued an skb we need to drop ref
 510	 */
 511	consume_skb(skb);
 512}
 513
 514static int kauditd_thread(void *dummy)
 515{
 516	set_freezable();
 517	while (!kthread_should_stop()) {
 518		struct sk_buff *skb;
 519
 520		flush_hold_queue();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 521
 522		skb = skb_dequeue(&audit_skb_queue);
 523
 524		if (skb) {
 525			if (!audit_backlog_limit ||
 526			    (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit))
 527				wake_up(&audit_backlog_wait);
 528			if (audit_pid)
 529				kauditd_send_skb(skb);
 530			else
 531				audit_printk_skb(skb);
 532			continue;
 533		}
 
 
 534
 535		wait_event_freezable(kauditd_wait, skb_queue_len(&audit_skb_queue));
 
 
 
 
 
 
 
 536	}
 537	return 0;
 538}
 539
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 540int audit_send_list(void *_dest)
 541{
 542	struct audit_netlink_list *dest = _dest;
 
 543	struct sk_buff *skb;
 544	struct net *net = dest->net;
 545	struct audit_net *aunet = net_generic(net, audit_net_id);
 546
 547	/* wait for parent to finish and send an ACK */
 548	mutex_lock(&audit_cmd_mutex);
 549	mutex_unlock(&audit_cmd_mutex);
 550
 551	while ((skb = __skb_dequeue(&dest->q)) != NULL)
 552		netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
 553
 554	put_net(net);
 555	kfree(dest);
 556
 557	return 0;
 558}
 559
 560struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
 561				 int multi, const void *payload, int size)
 562{
 563	struct sk_buff	*skb;
 564	struct nlmsghdr	*nlh;
 565	void		*data;
 566	int		flags = multi ? NLM_F_MULTI : 0;
 567	int		t     = done  ? NLMSG_DONE  : type;
 568
 569	skb = nlmsg_new(size, GFP_KERNEL);
 570	if (!skb)
 571		return NULL;
 572
 573	nlh	= nlmsg_put(skb, portid, seq, t, size, flags);
 574	if (!nlh)
 575		goto out_kfree_skb;
 576	data = nlmsg_data(nlh);
 577	memcpy(data, payload, size);
 578	return skb;
 579
 580out_kfree_skb:
 581	kfree_skb(skb);
 
 582	return NULL;
 583}
 584
 585static int audit_send_reply_thread(void *arg)
 586{
 587	struct audit_reply *reply = (struct audit_reply *)arg;
 588	struct net *net = reply->net;
 589	struct audit_net *aunet = net_generic(net, audit_net_id);
 590
 591	mutex_lock(&audit_cmd_mutex);
 592	mutex_unlock(&audit_cmd_mutex);
 593
 594	/* Ignore failure. It'll only happen if the sender goes away,
 595	   because our timeout is set to infinite. */
 596	netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
 597	put_net(net);
 598	kfree(reply);
 599	return 0;
 600}
 601/**
 602 * audit_send_reply - send an audit reply message via netlink
 603 * @request_skb: skb of request we are replying to (used to target the reply)
 604 * @seq: sequence number
 605 * @type: audit message type
 606 * @done: done (last) flag
 607 * @multi: multi-part message flag
 608 * @payload: payload data
 609 * @size: payload size
 610 *
 611 * Allocates an skb, builds the netlink message, and sends it to the port id.
 612 * No failure notifications.
 613 */
 614static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
 615			     int multi, const void *payload, int size)
 616{
 617	u32 portid = NETLINK_CB(request_skb).portid;
 618	struct net *net = sock_net(NETLINK_CB(request_skb).sk);
 619	struct sk_buff *skb;
 620	struct task_struct *tsk;
 621	struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
 622					    GFP_KERNEL);
 623
 624	if (!reply)
 625		return;
 626
 627	skb = audit_make_reply(portid, seq, type, done, multi, payload, size);
 628	if (!skb)
 629		goto out;
 630
 631	reply->net = get_net(net);
 632	reply->portid = portid;
 633	reply->skb = skb;
 634
 635	tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
 636	if (!IS_ERR(tsk))
 637		return;
 638	kfree_skb(skb);
 639out:
 640	kfree(reply);
 641}
 642
 643/*
 644 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 645 * control messages.
 646 */
 647static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 648{
 649	int err = 0;
 650
 651	/* Only support initial user namespace for now. */
 652	/*
 653	 * We return ECONNREFUSED because it tricks userspace into thinking
 654	 * that audit was not configured into the kernel.  Lots of users
 655	 * configure their PAM stack (because that's what the distro does)
 656	 * to reject login if unable to send messages to audit.  If we return
 657	 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
 658	 * configured in and will let login proceed.  If we return EPERM
 659	 * userspace will reject all logins.  This should be removed when we
 660	 * support non init namespaces!!
 661	 */
 662	if (current_user_ns() != &init_user_ns)
 663		return -ECONNREFUSED;
 664
 665	switch (msg_type) {
 666	case AUDIT_LIST:
 667	case AUDIT_ADD:
 668	case AUDIT_DEL:
 669		return -EOPNOTSUPP;
 670	case AUDIT_GET:
 671	case AUDIT_SET:
 672	case AUDIT_GET_FEATURE:
 673	case AUDIT_SET_FEATURE:
 674	case AUDIT_LIST_RULES:
 
 
 675	case AUDIT_ADD_RULE:
 
 676	case AUDIT_DEL_RULE:
 677	case AUDIT_SIGNAL_INFO:
 678	case AUDIT_TTY_GET:
 679	case AUDIT_TTY_SET:
 680	case AUDIT_TRIM:
 681	case AUDIT_MAKE_EQUIV:
 682		/* Only support auditd and auditctl in initial pid namespace
 683		 * for now. */
 684		if (task_active_pid_ns(current) != &init_pid_ns)
 685			return -EPERM;
 686
 687		if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
 688			err = -EPERM;
 689		break;
 690	case AUDIT_USER:
 691	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 692	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 693		if (!netlink_capable(skb, CAP_AUDIT_WRITE))
 694			err = -EPERM;
 695		break;
 696	default:  /* bad msg */
 697		err = -EINVAL;
 698	}
 699
 700	return err;
 701}
 702
 703static void audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
 
 
 704{
 705	uid_t uid = from_kuid(&init_user_ns, current_uid());
 706	pid_t pid = task_tgid_nr(current);
 
 707
 708	if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
 709		*ab = NULL;
 710		return;
 711	}
 712
 713	*ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 714	if (unlikely(!*ab))
 715		return;
 716	audit_log_format(*ab, "pid=%d uid=%u", pid, uid);
 717	audit_log_session_info(*ab);
 718	audit_log_task_context(*ab);
 719}
 720
 721int is_audit_feature_set(int i)
 722{
 723	return af.features & AUDIT_FEATURE_TO_MASK(i);
 724}
 725
 726
 727static int audit_get_feature(struct sk_buff *skb)
 728{
 729	u32 seq;
 730
 731	seq = nlmsg_hdr(skb)->nlmsg_seq;
 732
 733	audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
 734
 735	return 0;
 736}
 737
 738static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
 739				     u32 old_lock, u32 new_lock, int res)
 740{
 741	struct audit_buffer *ab;
 742
 743	if (audit_enabled == AUDIT_OFF)
 744		return;
 745
 746	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
 747	audit_log_task_info(ab, current);
 748	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
 749			 audit_feature_names[which], !!old_feature, !!new_feature,
 750			 !!old_lock, !!new_lock, res);
 751	audit_log_end(ab);
 752}
 753
 754static int audit_set_feature(struct sk_buff *skb)
 755{
 756	struct audit_features *uaf;
 757	int i;
 758
 759	BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
 760	uaf = nlmsg_data(nlmsg_hdr(skb));
 761
 762	/* if there is ever a version 2 we should handle that here */
 763
 764	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
 765		u32 feature = AUDIT_FEATURE_TO_MASK(i);
 766		u32 old_feature, new_feature, old_lock, new_lock;
 767
 768		/* if we are not changing this feature, move along */
 769		if (!(feature & uaf->mask))
 770			continue;
 771
 772		old_feature = af.features & feature;
 773		new_feature = uaf->features & feature;
 774		new_lock = (uaf->lock | af.lock) & feature;
 775		old_lock = af.lock & feature;
 776
 777		/* are we changing a locked feature? */
 778		if (old_lock && (new_feature != old_feature)) {
 779			audit_log_feature_change(i, old_feature, new_feature,
 780						 old_lock, new_lock, 0);
 781			return -EPERM;
 782		}
 783	}
 784	/* nothing invalid, do the changes */
 785	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
 786		u32 feature = AUDIT_FEATURE_TO_MASK(i);
 787		u32 old_feature, new_feature, old_lock, new_lock;
 788
 789		/* if we are not changing this feature, move along */
 790		if (!(feature & uaf->mask))
 791			continue;
 792
 793		old_feature = af.features & feature;
 794		new_feature = uaf->features & feature;
 795		old_lock = af.lock & feature;
 796		new_lock = (uaf->lock | af.lock) & feature;
 797
 798		if (new_feature != old_feature)
 799			audit_log_feature_change(i, old_feature, new_feature,
 800						 old_lock, new_lock, 1);
 801
 802		if (new_feature)
 803			af.features |= feature;
 804		else
 805			af.features &= ~feature;
 806		af.lock |= new_lock;
 807	}
 808
 809	return 0;
 810}
 811
 812static int audit_replace(pid_t pid)
 813{
 814	struct sk_buff *skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0,
 815					       &pid, sizeof(pid));
 816
 817	if (!skb)
 818		return -ENOMEM;
 819	return netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
 820}
 821
 822static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 823{
 824	u32			seq;
 825	void			*data;
 
 826	int			err;
 827	struct audit_buffer	*ab;
 828	u16			msg_type = nlh->nlmsg_type;
 
 
 829	struct audit_sig_info   *sig_data;
 830	char			*ctx = NULL;
 831	u32			len;
 832
 833	err = audit_netlink_ok(skb, msg_type);
 834	if (err)
 835		return err;
 836
 837	/* As soon as there's any sign of userspace auditd,
 838	 * start kauditd to talk to it */
 839	if (!kauditd_task) {
 840		kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 841		if (IS_ERR(kauditd_task)) {
 842			err = PTR_ERR(kauditd_task);
 843			kauditd_task = NULL;
 844			return err;
 845		}
 846	}
 
 
 
 
 
 
 847	seq  = nlh->nlmsg_seq;
 848	data = nlmsg_data(nlh);
 849
 850	switch (msg_type) {
 851	case AUDIT_GET: {
 852		struct audit_status	s;
 853		memset(&s, 0, sizeof(s));
 854		s.enabled		= audit_enabled;
 855		s.failure		= audit_failure;
 856		s.pid			= audit_pid;
 857		s.rate_limit		= audit_rate_limit;
 858		s.backlog_limit		= audit_backlog_limit;
 859		s.lost			= atomic_read(&audit_lost);
 860		s.backlog		= skb_queue_len(&audit_skb_queue);
 861		s.feature_bitmap	= AUDIT_FEATURE_BITMAP_ALL;
 862		s.backlog_wait_time	= audit_backlog_wait_time_master;
 863		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
 864		break;
 865	}
 866	case AUDIT_SET: {
 867		struct audit_status	s;
 868		memset(&s, 0, sizeof(s));
 869		/* guard against past and future API changes */
 870		memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
 871		if (s.mask & AUDIT_STATUS_ENABLED) {
 872			err = audit_set_enabled(s.enabled);
 873			if (err < 0)
 874				return err;
 875		}
 876		if (s.mask & AUDIT_STATUS_FAILURE) {
 877			err = audit_set_failure(s.failure);
 
 878			if (err < 0)
 879				return err;
 880		}
 881		if (s.mask & AUDIT_STATUS_PID) {
 882			int new_pid = s.pid;
 883			pid_t requesting_pid = task_tgid_vnr(current);
 884
 885			if ((!new_pid) && (requesting_pid != audit_pid)) {
 886				audit_log_config_change("audit_pid", new_pid, audit_pid, 0);
 887				return -EACCES;
 888			}
 889			if (audit_pid && new_pid &&
 890			    audit_replace(requesting_pid) != -ECONNREFUSED) {
 891				audit_log_config_change("audit_pid", new_pid, audit_pid, 0);
 892				return -EEXIST;
 893			}
 894			if (audit_enabled != AUDIT_OFF)
 895				audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
 
 
 
 896			audit_pid = new_pid;
 897			audit_nlk_portid = NETLINK_CB(skb).portid;
 898			audit_sock = skb->sk;
 899		}
 900		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
 901			err = audit_set_rate_limit(s.rate_limit);
 902			if (err < 0)
 903				return err;
 904		}
 905		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
 906			err = audit_set_backlog_limit(s.backlog_limit);
 
 907			if (err < 0)
 908				return err;
 909		}
 910		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
 911			if (sizeof(s) > (size_t)nlh->nlmsg_len)
 912				return -EINVAL;
 913			if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
 914				return -EINVAL;
 915			err = audit_set_backlog_wait_time(s.backlog_wait_time);
 916			if (err < 0)
 917				return err;
 918		}
 919		break;
 920	}
 921	case AUDIT_GET_FEATURE:
 922		err = audit_get_feature(skb);
 923		if (err)
 924			return err;
 925		break;
 926	case AUDIT_SET_FEATURE:
 927		err = audit_set_feature(skb);
 928		if (err)
 929			return err;
 930		break;
 931	case AUDIT_USER:
 932	case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 933	case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 934		if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 935			return 0;
 936
 937		err = audit_filter_user(msg_type);
 938		if (err == 1) { /* match or error */
 939			err = 0;
 940			if (msg_type == AUDIT_USER_TTY) {
 941				err = tty_audit_push();
 
 942				if (err)
 943					break;
 944			}
 945			mutex_unlock(&audit_cmd_mutex);
 946			audit_log_common_recv_msg(&ab, msg_type);
 
 947			if (msg_type != AUDIT_USER_TTY)
 948				audit_log_format(ab, " msg='%.*s'",
 949						 AUDIT_MESSAGE_TEXT_MAX,
 950						 (char *)data);
 951			else {
 952				int size;
 953
 954				audit_log_format(ab, " data=");
 955				size = nlmsg_len(nlh);
 956				if (size > 0 &&
 957				    ((unsigned char *)data)[size - 1] == '\0')
 958					size--;
 959				audit_log_n_untrustedstring(ab, data, size);
 960			}
 961			audit_set_portid(ab, NETLINK_CB(skb).portid);
 962			audit_log_end(ab);
 963			mutex_lock(&audit_cmd_mutex);
 964		}
 965		break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 966	case AUDIT_ADD_RULE:
 967	case AUDIT_DEL_RULE:
 968		if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 969			return -EINVAL;
 970		if (audit_enabled == AUDIT_LOCKED) {
 971			audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
 972			audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
 
 
 
 973			audit_log_end(ab);
 974			return -EPERM;
 975		}
 976		err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
 977					   seq, data, nlmsg_len(nlh));
 978		break;
 979	case AUDIT_LIST_RULES:
 980		err = audit_list_rules_send(skb, seq);
 
 
 981		break;
 982	case AUDIT_TRIM:
 983		audit_trim_trees();
 984		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
 
 
 
 985		audit_log_format(ab, " op=trim res=1");
 986		audit_log_end(ab);
 987		break;
 988	case AUDIT_MAKE_EQUIV: {
 989		void *bufp = data;
 990		u32 sizes[2];
 991		size_t msglen = nlmsg_len(nlh);
 992		char *old, *new;
 993
 994		err = -EINVAL;
 995		if (msglen < 2 * sizeof(u32))
 996			break;
 997		memcpy(sizes, bufp, 2 * sizeof(u32));
 998		bufp += 2 * sizeof(u32);
 999		msglen -= 2 * sizeof(u32);
1000		old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1001		if (IS_ERR(old)) {
1002			err = PTR_ERR(old);
1003			break;
1004		}
1005		new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1006		if (IS_ERR(new)) {
1007			err = PTR_ERR(new);
1008			kfree(old);
1009			break;
1010		}
1011		/* OK, here comes... */
1012		err = audit_tag_tree(old, new);
1013
1014		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
 
1015
1016		audit_log_format(ab, " op=make_equiv old=");
1017		audit_log_untrustedstring(ab, old);
1018		audit_log_format(ab, " new=");
1019		audit_log_untrustedstring(ab, new);
1020		audit_log_format(ab, " res=%d", !err);
1021		audit_log_end(ab);
1022		kfree(old);
1023		kfree(new);
1024		break;
1025	}
1026	case AUDIT_SIGNAL_INFO:
1027		len = 0;
1028		if (audit_sig_sid) {
1029			err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1030			if (err)
1031				return err;
1032		}
1033		sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1034		if (!sig_data) {
1035			if (audit_sig_sid)
1036				security_release_secctx(ctx, len);
1037			return -ENOMEM;
1038		}
1039		sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1040		sig_data->pid = audit_sig_pid;
1041		if (audit_sig_sid) {
1042			memcpy(sig_data->ctx, ctx, len);
1043			security_release_secctx(ctx, len);
1044		}
1045		audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1046				 sig_data, sizeof(*sig_data) + len);
1047		kfree(sig_data);
1048		break;
1049	case AUDIT_TTY_GET: {
1050		struct audit_tty_status s;
1051		unsigned int t;
 
1052
1053		t = READ_ONCE(current->signal->audit_tty);
1054		s.enabled = t & AUDIT_TTY_ENABLE;
1055		s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1056
1057		audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
 
 
 
 
 
 
 
1058		break;
1059	}
1060	case AUDIT_TTY_SET: {
1061		struct audit_tty_status s, old;
1062		struct audit_buffer	*ab;
1063		unsigned int t;
1064
1065		memset(&s, 0, sizeof(s));
1066		/* guard against past and future API changes */
1067		memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1068		/* check if new data is valid */
1069		if ((s.enabled != 0 && s.enabled != 1) ||
1070		    (s.log_passwd != 0 && s.log_passwd != 1))
1071			err = -EINVAL;
1072
1073		if (err)
1074			t = READ_ONCE(current->signal->audit_tty);
1075		else {
1076			t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1077			t = xchg(&current->signal->audit_tty, t);
1078		}
1079		old.enabled = t & AUDIT_TTY_ENABLE;
1080		old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1081
1082		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1083		audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1084				 " old-log_passwd=%d new-log_passwd=%d res=%d",
1085				 old.enabled, s.enabled, old.log_passwd,
1086				 s.log_passwd, !err);
1087		audit_log_end(ab);
 
 
 
 
 
 
 
1088		break;
1089	}
1090	default:
1091		err = -EINVAL;
1092		break;
1093	}
1094
1095	return err < 0 ? err : 0;
1096}
1097
1098/*
1099 * Get message from skb.  Each message is processed by audit_receive_msg.
1100 * Malformed skbs with wrong length are discarded silently.
1101 */
1102static void audit_receive_skb(struct sk_buff *skb)
1103{
1104	struct nlmsghdr *nlh;
1105	/*
1106	 * len MUST be signed for nlmsg_next to be able to dec it below 0
1107	 * if the nlmsg_len was not aligned
1108	 */
1109	int len;
1110	int err;
1111
1112	nlh = nlmsg_hdr(skb);
1113	len = skb->len;
1114
1115	while (nlmsg_ok(nlh, len)) {
1116		err = audit_receive_msg(skb, nlh);
1117		/* if err or if this message says it wants a response */
1118		if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1119			netlink_ack(skb, nlh, err);
1120
1121		nlh = nlmsg_next(nlh, &len);
1122	}
1123}
1124
1125/* Receive messages from netlink socket. */
1126static void audit_receive(struct sk_buff  *skb)
1127{
1128	mutex_lock(&audit_cmd_mutex);
1129	audit_receive_skb(skb);
1130	mutex_unlock(&audit_cmd_mutex);
1131}
1132
1133/* Run custom bind function on netlink socket group connect or bind requests. */
1134static int audit_bind(struct net *net, int group)
1135{
1136	if (!capable(CAP_AUDIT_READ))
1137		return -EPERM;
1138
1139	return 0;
1140}
1141
1142static int __net_init audit_net_init(struct net *net)
1143{
1144	struct netlink_kernel_cfg cfg = {
1145		.input	= audit_receive,
1146		.bind	= audit_bind,
1147		.flags	= NL_CFG_F_NONROOT_RECV,
1148		.groups	= AUDIT_NLGRP_MAX,
1149	};
1150
1151	struct audit_net *aunet = net_generic(net, audit_net_id);
1152
1153	aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1154	if (aunet->nlsk == NULL) {
1155		audit_panic("cannot initialize netlink socket in namespace");
1156		return -ENOMEM;
1157	}
1158	aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1159	return 0;
1160}
1161
1162static void __net_exit audit_net_exit(struct net *net)
1163{
1164	struct audit_net *aunet = net_generic(net, audit_net_id);
1165	struct sock *sock = aunet->nlsk;
1166	if (sock == audit_sock) {
1167		audit_pid = 0;
1168		audit_sock = NULL;
1169	}
1170
1171	RCU_INIT_POINTER(aunet->nlsk, NULL);
1172	synchronize_net();
1173	netlink_kernel_release(sock);
1174}
1175
1176static struct pernet_operations audit_net_ops __net_initdata = {
1177	.init = audit_net_init,
1178	.exit = audit_net_exit,
1179	.id = &audit_net_id,
1180	.size = sizeof(struct audit_net),
1181};
1182
1183/* Initialize audit support at boot time. */
1184static int __init audit_init(void)
1185{
1186	int i;
1187
1188	if (audit_initialized == AUDIT_DISABLED)
1189		return 0;
1190
1191	pr_info("initializing netlink subsys (%s)\n",
1192		audit_default ? "enabled" : "disabled");
1193	register_pernet_subsys(&audit_net_ops);
 
 
 
 
 
1194
1195	skb_queue_head_init(&audit_skb_queue);
1196	skb_queue_head_init(&audit_skb_hold_queue);
1197	audit_initialized = AUDIT_INITIALIZED;
1198	audit_enabled = audit_default;
1199	audit_ever_enabled |= !!audit_default;
1200
1201	audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
1202
1203	for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1204		INIT_LIST_HEAD(&audit_inode_hash[i]);
1205
1206	return 0;
1207}
1208__initcall(audit_init);
1209
1210/* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
1211static int __init audit_enable(char *str)
1212{
1213	audit_default = !!simple_strtol(str, NULL, 0);
1214	if (!audit_default)
1215		audit_initialized = AUDIT_DISABLED;
1216
1217	pr_info("%s\n", audit_default ?
1218		"enabled (after initialization)" : "disabled (until reboot)");
1219
1220	return 1;
1221}
1222__setup("audit=", audit_enable);
1223
1224/* Process kernel command-line parameter at boot time.
1225 * audit_backlog_limit=<n> */
1226static int __init audit_backlog_limit_set(char *str)
1227{
1228	u32 audit_backlog_limit_arg;
1229
1230	pr_info("audit_backlog_limit: ");
1231	if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1232		pr_cont("using default of %u, unable to parse %s\n",
1233			audit_backlog_limit, str);
1234		return 1;
1235	}
1236
1237	audit_backlog_limit = audit_backlog_limit_arg;
1238	pr_cont("%d\n", audit_backlog_limit);
1239
1240	return 1;
1241}
1242__setup("audit_backlog_limit=", audit_backlog_limit_set);
 
1243
1244static void audit_buffer_free(struct audit_buffer *ab)
1245{
1246	unsigned long flags;
1247
1248	if (!ab)
1249		return;
1250
1251	kfree_skb(ab->skb);
 
 
1252	spin_lock_irqsave(&audit_freelist_lock, flags);
1253	if (audit_freelist_count > AUDIT_MAXFREE)
1254		kfree(ab);
1255	else {
1256		audit_freelist_count++;
1257		list_add(&ab->list, &audit_freelist);
1258	}
1259	spin_unlock_irqrestore(&audit_freelist_lock, flags);
1260}
1261
1262static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1263						gfp_t gfp_mask, int type)
1264{
1265	unsigned long flags;
1266	struct audit_buffer *ab = NULL;
1267	struct nlmsghdr *nlh;
1268
1269	spin_lock_irqsave(&audit_freelist_lock, flags);
1270	if (!list_empty(&audit_freelist)) {
1271		ab = list_entry(audit_freelist.next,
1272				struct audit_buffer, list);
1273		list_del(&ab->list);
1274		--audit_freelist_count;
1275	}
1276	spin_unlock_irqrestore(&audit_freelist_lock, flags);
1277
1278	if (!ab) {
1279		ab = kmalloc(sizeof(*ab), gfp_mask);
1280		if (!ab)
1281			goto err;
1282	}
1283
1284	ab->ctx = ctx;
1285	ab->gfp_mask = gfp_mask;
1286
1287	ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1288	if (!ab->skb)
1289		goto err;
1290
1291	nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1292	if (!nlh)
1293		goto out_kfree_skb;
1294
1295	return ab;
1296
1297out_kfree_skb:
1298	kfree_skb(ab->skb);
1299	ab->skb = NULL;
1300err:
1301	audit_buffer_free(ab);
1302	return NULL;
1303}
1304
1305/**
1306 * audit_serial - compute a serial number for the audit record
1307 *
1308 * Compute a serial number for the audit record.  Audit records are
1309 * written to user-space as soon as they are generated, so a complete
1310 * audit record may be written in several pieces.  The timestamp of the
1311 * record and this serial number are used by the user-space tools to
1312 * determine which pieces belong to the same audit record.  The
1313 * (timestamp,serial) tuple is unique for each syscall and is live from
1314 * syscall entry to syscall exit.
1315 *
1316 * NOTE: Another possibility is to store the formatted records off the
1317 * audit context (for those records that have a context), and emit them
1318 * all at syscall exit.  However, this could delay the reporting of
1319 * significant errors until syscall exit (or never, if the system
1320 * halts).
1321 */
1322unsigned int audit_serial(void)
1323{
1324	static atomic_t serial = ATOMIC_INIT(0);
 
1325
1326	return atomic_add_return(1, &serial);
 
 
 
 
 
 
 
 
 
1327}
1328
1329static inline void audit_get_stamp(struct audit_context *ctx,
1330				   struct timespec *t, unsigned int *serial)
1331{
1332	if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1333		*t = CURRENT_TIME;
1334		*serial = audit_serial();
1335	}
1336}
1337
1338/*
1339 * Wait for auditd to drain the queue a little
1340 */
1341static long wait_for_auditd(long sleep_time)
1342{
1343	DECLARE_WAITQUEUE(wait, current);
1344	set_current_state(TASK_UNINTERRUPTIBLE);
1345	add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1346
1347	if (audit_backlog_limit &&
1348	    skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1349		sleep_time = schedule_timeout(sleep_time);
1350
1351	__set_current_state(TASK_RUNNING);
1352	remove_wait_queue(&audit_backlog_wait, &wait);
1353
1354	return sleep_time;
1355}
1356
1357/**
1358 * audit_log_start - obtain an audit buffer
1359 * @ctx: audit_context (may be NULL)
1360 * @gfp_mask: type of allocation
1361 * @type: audit message type
1362 *
1363 * Returns audit_buffer pointer on success or NULL on error.
1364 *
1365 * Obtain an audit buffer.  This routine does locking to obtain the
1366 * audit buffer, but then no locking is required for calls to
1367 * audit_log_*format.  If the task (ctx) is a task that is currently in a
1368 * syscall, then the syscall is marked as auditable and an audit record
1369 * will be written at syscall exit.  If there is no associated task, then
1370 * task context (ctx) should be NULL.
1371 */
1372struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1373				     int type)
1374{
1375	struct audit_buffer	*ab	= NULL;
1376	struct timespec		t;
1377	unsigned int		uninitialized_var(serial);
1378	int reserve = 5; /* Allow atomic callers to go up to five
1379			    entries over the normal backlog limit */
1380	unsigned long timeout_start = jiffies;
1381
1382	if (audit_initialized != AUDIT_INITIALIZED)
1383		return NULL;
1384
1385	if (unlikely(audit_filter_type(type)))
1386		return NULL;
1387
1388	if (gfp_mask & __GFP_DIRECT_RECLAIM) {
1389		if (audit_pid && audit_pid == current->tgid)
1390			gfp_mask &= ~__GFP_DIRECT_RECLAIM;
1391		else
1392			reserve = 0;
1393	}
1394
1395	while (audit_backlog_limit
1396	       && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1397		if (gfp_mask & __GFP_DIRECT_RECLAIM && audit_backlog_wait_time) {
1398			long sleep_time;
1399
1400			sleep_time = timeout_start + audit_backlog_wait_time - jiffies;
1401			if (sleep_time > 0) {
1402				sleep_time = wait_for_auditd(sleep_time);
1403				if (sleep_time > 0)
1404					continue;
1405			}
 
 
 
 
 
 
1406		}
1407		if (audit_rate_check() && printk_ratelimit())
1408			pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1409				skb_queue_len(&audit_skb_queue),
1410				audit_backlog_limit);
 
 
1411		audit_log_lost("backlog limit exceeded");
1412		audit_backlog_wait_time = 0;
1413		wake_up(&audit_backlog_wait);
1414		return NULL;
1415	}
1416
1417	if (!reserve && !audit_backlog_wait_time)
1418		audit_backlog_wait_time = audit_backlog_wait_time_master;
1419
1420	ab = audit_buffer_alloc(ctx, gfp_mask, type);
1421	if (!ab) {
1422		audit_log_lost("out of memory in audit_log_start");
1423		return NULL;
1424	}
1425
1426	audit_get_stamp(ab->ctx, &t, &serial);
1427
1428	audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1429			 t.tv_sec, t.tv_nsec/1000000, serial);
1430	return ab;
1431}
1432
1433/**
1434 * audit_expand - expand skb in the audit buffer
1435 * @ab: audit_buffer
1436 * @extra: space to add at tail of the skb
1437 *
1438 * Returns 0 (no space) on failed expansion, or available space if
1439 * successful.
1440 */
1441static inline int audit_expand(struct audit_buffer *ab, int extra)
1442{
1443	struct sk_buff *skb = ab->skb;
1444	int oldtail = skb_tailroom(skb);
1445	int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1446	int newtail = skb_tailroom(skb);
1447
1448	if (ret < 0) {
1449		audit_log_lost("out of memory in audit_expand");
1450		return 0;
1451	}
1452
1453	skb->truesize += newtail - oldtail;
1454	return newtail;
1455}
1456
1457/*
1458 * Format an audit message into the audit buffer.  If there isn't enough
1459 * room in the audit buffer, more room will be allocated and vsnprint
1460 * will be called a second time.  Currently, we assume that a printk
1461 * can't format message larger than 1024 bytes, so we don't either.
1462 */
1463static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1464			      va_list args)
1465{
1466	int len, avail;
1467	struct sk_buff *skb;
1468	va_list args2;
1469
1470	if (!ab)
1471		return;
1472
1473	BUG_ON(!ab->skb);
1474	skb = ab->skb;
1475	avail = skb_tailroom(skb);
1476	if (avail == 0) {
1477		avail = audit_expand(ab, AUDIT_BUFSIZ);
1478		if (!avail)
1479			goto out;
1480	}
1481	va_copy(args2, args);
1482	len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1483	if (len >= avail) {
1484		/* The printk buffer is 1024 bytes long, so if we get
1485		 * here and AUDIT_BUFSIZ is at least 1024, then we can
1486		 * log everything that printk could have logged. */
1487		avail = audit_expand(ab,
1488			max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1489		if (!avail)
1490			goto out_va_end;
1491		len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1492	}
 
1493	if (len > 0)
1494		skb_put(skb, len);
1495out_va_end:
1496	va_end(args2);
1497out:
1498	return;
1499}
1500
1501/**
1502 * audit_log_format - format a message into the audit buffer.
1503 * @ab: audit_buffer
1504 * @fmt: format string
1505 * @...: optional parameters matching @fmt string
1506 *
1507 * All the work is done in audit_log_vformat.
1508 */
1509void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1510{
1511	va_list args;
1512
1513	if (!ab)
1514		return;
1515	va_start(args, fmt);
1516	audit_log_vformat(ab, fmt, args);
1517	va_end(args);
1518}
1519
1520/**
1521 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1522 * @ab: the audit_buffer
1523 * @buf: buffer to convert to hex
1524 * @len: length of @buf to be converted
1525 *
1526 * No return value; failure to expand is silently ignored.
1527 *
1528 * This function will take the passed buf and convert it into a string of
1529 * ascii hex digits. The new string is placed onto the skb.
1530 */
1531void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1532		size_t len)
1533{
1534	int i, avail, new_len;
1535	unsigned char *ptr;
1536	struct sk_buff *skb;
 
1537
1538	if (!ab)
1539		return;
1540
1541	BUG_ON(!ab->skb);
1542	skb = ab->skb;
1543	avail = skb_tailroom(skb);
1544	new_len = len<<1;
1545	if (new_len >= avail) {
1546		/* Round the buffer request up to the next multiple */
1547		new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1548		avail = audit_expand(ab, new_len);
1549		if (!avail)
1550			return;
1551	}
1552
1553	ptr = skb_tail_pointer(skb);
1554	for (i = 0; i < len; i++)
1555		ptr = hex_byte_pack_upper(ptr, buf[i]);
 
 
1556	*ptr = 0;
1557	skb_put(skb, len << 1); /* new string is twice the old string */
1558}
1559
1560/*
1561 * Format a string of no more than slen characters into the audit buffer,
1562 * enclosed in quote marks.
1563 */
1564void audit_log_n_string(struct audit_buffer *ab, const char *string,
1565			size_t slen)
1566{
1567	int avail, new_len;
1568	unsigned char *ptr;
1569	struct sk_buff *skb;
1570
1571	if (!ab)
1572		return;
1573
1574	BUG_ON(!ab->skb);
1575	skb = ab->skb;
1576	avail = skb_tailroom(skb);
1577	new_len = slen + 3;	/* enclosing quotes + null terminator */
1578	if (new_len > avail) {
1579		avail = audit_expand(ab, new_len);
1580		if (!avail)
1581			return;
1582	}
1583	ptr = skb_tail_pointer(skb);
1584	*ptr++ = '"';
1585	memcpy(ptr, string, slen);
1586	ptr += slen;
1587	*ptr++ = '"';
1588	*ptr = 0;
1589	skb_put(skb, slen + 2);	/* don't include null terminator */
1590}
1591
1592/**
1593 * audit_string_contains_control - does a string need to be logged in hex
1594 * @string: string to be checked
1595 * @len: max length of the string to check
1596 */
1597bool audit_string_contains_control(const char *string, size_t len)
1598{
1599	const unsigned char *p;
1600	for (p = string; p < (const unsigned char *)string + len; p++) {
1601		if (*p == '"' || *p < 0x21 || *p > 0x7e)
1602			return true;
1603	}
1604	return false;
1605}
1606
1607/**
1608 * audit_log_n_untrustedstring - log a string that may contain random characters
1609 * @ab: audit_buffer
1610 * @len: length of string (not including trailing null)
1611 * @string: string to be logged
1612 *
1613 * This code will escape a string that is passed to it if the string
1614 * contains a control character, unprintable character, double quote mark,
1615 * or a space. Unescaped strings will start and end with a double quote mark.
1616 * Strings that are escaped are printed in hex (2 digits per char).
1617 *
1618 * The caller specifies the number of characters in the string to log, which may
1619 * or may not be the entire string.
1620 */
1621void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1622				 size_t len)
1623{
1624	if (audit_string_contains_control(string, len))
1625		audit_log_n_hex(ab, string, len);
1626	else
1627		audit_log_n_string(ab, string, len);
1628}
1629
1630/**
1631 * audit_log_untrustedstring - log a string that may contain random characters
1632 * @ab: audit_buffer
1633 * @string: string to be logged
1634 *
1635 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1636 * determine string length.
1637 */
1638void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1639{
1640	audit_log_n_untrustedstring(ab, string, strlen(string));
1641}
1642
1643/* This is a helper-function to print the escaped d_path */
1644void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1645		      const struct path *path)
1646{
1647	char *p, *pathname;
1648
1649	if (prefix)
1650		audit_log_format(ab, "%s", prefix);
1651
1652	/* We will allow 11 spaces for ' (deleted)' to be appended */
1653	pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1654	if (!pathname) {
1655		audit_log_string(ab, "<no_memory>");
1656		return;
1657	}
1658	p = d_path(path, pathname, PATH_MAX+11);
1659	if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1660		/* FIXME: can we save some information here? */
1661		audit_log_string(ab, "<too_long>");
1662	} else
1663		audit_log_untrustedstring(ab, p);
1664	kfree(pathname);
1665}
1666
1667void audit_log_session_info(struct audit_buffer *ab)
1668{
1669	unsigned int sessionid = audit_get_sessionid(current);
1670	uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1671
1672	audit_log_format(ab, " auid=%u ses=%u", auid, sessionid);
1673}
1674
1675void audit_log_key(struct audit_buffer *ab, char *key)
1676{
1677	audit_log_format(ab, " key=");
1678	if (key)
1679		audit_log_untrustedstring(ab, key);
1680	else
1681		audit_log_format(ab, "(null)");
1682}
1683
1684void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1685{
1686	int i;
1687
1688	audit_log_format(ab, " %s=", prefix);
1689	CAP_FOR_EACH_U32(i) {
1690		audit_log_format(ab, "%08x",
1691				 cap->cap[CAP_LAST_U32 - i]);
1692	}
1693}
1694
1695static void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1696{
1697	kernel_cap_t *perm = &name->fcap.permitted;
1698	kernel_cap_t *inh = &name->fcap.inheritable;
1699	int log = 0;
1700
1701	if (!cap_isclear(*perm)) {
1702		audit_log_cap(ab, "cap_fp", perm);
1703		log = 1;
1704	}
1705	if (!cap_isclear(*inh)) {
1706		audit_log_cap(ab, "cap_fi", inh);
1707		log = 1;
1708	}
1709
1710	if (log)
1711		audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1712				 name->fcap.fE, name->fcap_ver);
1713}
1714
1715static inline int audit_copy_fcaps(struct audit_names *name,
1716				   const struct dentry *dentry)
1717{
1718	struct cpu_vfs_cap_data caps;
1719	int rc;
1720
1721	if (!dentry)
1722		return 0;
1723
1724	rc = get_vfs_caps_from_disk(dentry, &caps);
1725	if (rc)
1726		return rc;
1727
1728	name->fcap.permitted = caps.permitted;
1729	name->fcap.inheritable = caps.inheritable;
1730	name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1731	name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1732				VFS_CAP_REVISION_SHIFT;
1733
1734	return 0;
1735}
1736
1737/* Copy inode data into an audit_names. */
1738void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1739		      struct inode *inode)
1740{
1741	name->ino   = inode->i_ino;
1742	name->dev   = inode->i_sb->s_dev;
1743	name->mode  = inode->i_mode;
1744	name->uid   = inode->i_uid;
1745	name->gid   = inode->i_gid;
1746	name->rdev  = inode->i_rdev;
1747	security_inode_getsecid(inode, &name->osid);
1748	audit_copy_fcaps(name, dentry);
1749}
1750
1751/**
1752 * audit_log_name - produce AUDIT_PATH record from struct audit_names
1753 * @context: audit_context for the task
1754 * @n: audit_names structure with reportable details
1755 * @path: optional path to report instead of audit_names->name
1756 * @record_num: record number to report when handling a list of names
1757 * @call_panic: optional pointer to int that will be updated if secid fails
1758 */
1759void audit_log_name(struct audit_context *context, struct audit_names *n,
1760		    struct path *path, int record_num, int *call_panic)
1761{
1762	struct audit_buffer *ab;
1763	ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1764	if (!ab)
1765		return;
1766
1767	audit_log_format(ab, "item=%d", record_num);
1768
1769	if (path)
1770		audit_log_d_path(ab, " name=", path);
1771	else if (n->name) {
1772		switch (n->name_len) {
1773		case AUDIT_NAME_FULL:
1774			/* log the full path */
1775			audit_log_format(ab, " name=");
1776			audit_log_untrustedstring(ab, n->name->name);
1777			break;
1778		case 0:
1779			/* name was specified as a relative path and the
1780			 * directory component is the cwd */
1781			audit_log_d_path(ab, " name=", &context->pwd);
1782			break;
1783		default:
1784			/* log the name's directory component */
1785			audit_log_format(ab, " name=");
1786			audit_log_n_untrustedstring(ab, n->name->name,
1787						    n->name_len);
1788		}
1789	} else
1790		audit_log_format(ab, " name=(null)");
1791
1792	if (n->ino != AUDIT_INO_UNSET)
1793		audit_log_format(ab, " inode=%lu"
1794				 " dev=%02x:%02x mode=%#ho"
1795				 " ouid=%u ogid=%u rdev=%02x:%02x",
1796				 n->ino,
1797				 MAJOR(n->dev),
1798				 MINOR(n->dev),
1799				 n->mode,
1800				 from_kuid(&init_user_ns, n->uid),
1801				 from_kgid(&init_user_ns, n->gid),
1802				 MAJOR(n->rdev),
1803				 MINOR(n->rdev));
1804	if (n->osid != 0) {
1805		char *ctx = NULL;
1806		u32 len;
1807		if (security_secid_to_secctx(
1808			n->osid, &ctx, &len)) {
1809			audit_log_format(ab, " osid=%u", n->osid);
1810			if (call_panic)
1811				*call_panic = 2;
1812		} else {
1813			audit_log_format(ab, " obj=%s", ctx);
1814			security_release_secctx(ctx, len);
1815		}
1816	}
1817
1818	/* log the audit_names record type */
1819	audit_log_format(ab, " nametype=");
1820	switch(n->type) {
1821	case AUDIT_TYPE_NORMAL:
1822		audit_log_format(ab, "NORMAL");
1823		break;
1824	case AUDIT_TYPE_PARENT:
1825		audit_log_format(ab, "PARENT");
1826		break;
1827	case AUDIT_TYPE_CHILD_DELETE:
1828		audit_log_format(ab, "DELETE");
1829		break;
1830	case AUDIT_TYPE_CHILD_CREATE:
1831		audit_log_format(ab, "CREATE");
1832		break;
1833	default:
1834		audit_log_format(ab, "UNKNOWN");
1835		break;
1836	}
1837
1838	audit_log_fcaps(ab, n);
1839	audit_log_end(ab);
1840}
1841
1842int audit_log_task_context(struct audit_buffer *ab)
1843{
1844	char *ctx = NULL;
1845	unsigned len;
1846	int error;
1847	u32 sid;
1848
1849	security_task_getsecid(current, &sid);
1850	if (!sid)
1851		return 0;
1852
1853	error = security_secid_to_secctx(sid, &ctx, &len);
1854	if (error) {
1855		if (error != -EINVAL)
1856			goto error_path;
1857		return 0;
1858	}
1859
1860	audit_log_format(ab, " subj=%s", ctx);
1861	security_release_secctx(ctx, len);
1862	return 0;
1863
1864error_path:
1865	audit_panic("error in audit_log_task_context");
1866	return error;
1867}
1868EXPORT_SYMBOL(audit_log_task_context);
1869
1870void audit_log_d_path_exe(struct audit_buffer *ab,
1871			  struct mm_struct *mm)
1872{
1873	struct file *exe_file;
1874
1875	if (!mm)
1876		goto out_null;
1877
1878	exe_file = get_mm_exe_file(mm);
1879	if (!exe_file)
1880		goto out_null;
1881
1882	audit_log_d_path(ab, " exe=", &exe_file->f_path);
1883	fput(exe_file);
1884	return;
1885out_null:
1886	audit_log_format(ab, " exe=(null)");
1887}
1888
1889void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
1890{
1891	const struct cred *cred;
1892	char comm[sizeof(tsk->comm)];
1893	char *tty;
1894
1895	if (!ab)
1896		return;
1897
1898	/* tsk == current */
1899	cred = current_cred();
1900
1901	spin_lock_irq(&tsk->sighand->siglock);
1902	if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
1903		tty = tsk->signal->tty->name;
1904	else
1905		tty = "(none)";
1906	spin_unlock_irq(&tsk->sighand->siglock);
1907
1908	audit_log_format(ab,
1909			 " ppid=%d pid=%d auid=%u uid=%u gid=%u"
1910			 " euid=%u suid=%u fsuid=%u"
1911			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
1912			 task_ppid_nr(tsk),
1913			 task_pid_nr(tsk),
1914			 from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
1915			 from_kuid(&init_user_ns, cred->uid),
1916			 from_kgid(&init_user_ns, cred->gid),
1917			 from_kuid(&init_user_ns, cred->euid),
1918			 from_kuid(&init_user_ns, cred->suid),
1919			 from_kuid(&init_user_ns, cred->fsuid),
1920			 from_kgid(&init_user_ns, cred->egid),
1921			 from_kgid(&init_user_ns, cred->sgid),
1922			 from_kgid(&init_user_ns, cred->fsgid),
1923			 tty, audit_get_sessionid(tsk));
1924
1925	audit_log_format(ab, " comm=");
1926	audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
1927
1928	audit_log_d_path_exe(ab, tsk->mm);
1929	audit_log_task_context(ab);
1930}
1931EXPORT_SYMBOL(audit_log_task_info);
1932
1933/**
1934 * audit_log_link_denied - report a link restriction denial
1935 * @operation: specific link operation
1936 * @link: the path that triggered the restriction
1937 */
1938void audit_log_link_denied(const char *operation, struct path *link)
1939{
1940	struct audit_buffer *ab;
1941	struct audit_names *name;
1942
1943	name = kzalloc(sizeof(*name), GFP_NOFS);
1944	if (!name)
1945		return;
1946
1947	/* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
1948	ab = audit_log_start(current->audit_context, GFP_KERNEL,
1949			     AUDIT_ANOM_LINK);
1950	if (!ab)
1951		goto out;
1952	audit_log_format(ab, "op=%s", operation);
1953	audit_log_task_info(ab, current);
1954	audit_log_format(ab, " res=0");
1955	audit_log_end(ab);
1956
1957	/* Generate AUDIT_PATH record with object. */
1958	name->type = AUDIT_TYPE_NORMAL;
1959	audit_copy_inode(name, link->dentry, d_backing_inode(link->dentry));
1960	audit_log_name(current->audit_context, name, link, 0, NULL);
1961out:
1962	kfree(name);
1963}
1964
1965/**
1966 * audit_log_end - end one audit record
1967 * @ab: the audit_buffer
1968 *
1969 * netlink_unicast() cannot be called inside an irq context because it blocks
1970 * (last arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed
1971 * on a queue and a tasklet is scheduled to remove them from the queue outside
1972 * the irq context.  May be called in any context.
1973 */
1974void audit_log_end(struct audit_buffer *ab)
1975{
1976	if (!ab)
1977		return;
1978	if (!audit_rate_check()) {
1979		audit_log_lost("rate limit exceeded");
1980	} else {
1981		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1982
1983		nlh->nlmsg_len = ab->skb->len;
1984		kauditd_send_multicast_skb(ab->skb, ab->gfp_mask);
1985
1986		/*
1987		 * The original kaudit unicast socket sends up messages with
1988		 * nlmsg_len set to the payload length rather than the entire
1989		 * message length.  This breaks the standard set by netlink.
1990		 * The existing auditd daemon assumes this breakage.  Fixing
1991		 * this would require co-ordinating a change in the established
1992		 * protocol between the kaudit kernel subsystem and the auditd
1993		 * userspace code.
1994		 */
1995		nlh->nlmsg_len -= NLMSG_HDRLEN;
1996
1997		if (audit_pid) {
1998			skb_queue_tail(&audit_skb_queue, ab->skb);
1999			wake_up_interruptible(&kauditd_wait);
2000		} else {
2001			audit_printk_skb(ab->skb);
2002		}
2003		ab->skb = NULL;
2004	}
2005	audit_buffer_free(ab);
2006}
2007
2008/**
2009 * audit_log - Log an audit record
2010 * @ctx: audit context
2011 * @gfp_mask: type of allocation
2012 * @type: audit message type
2013 * @fmt: format string to use
2014 * @...: variable parameters matching the format string
2015 *
2016 * This is a convenience function that calls audit_log_start,
2017 * audit_log_vformat, and audit_log_end.  It may be called
2018 * in any context.
2019 */
2020void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2021	       const char *fmt, ...)
2022{
2023	struct audit_buffer *ab;
2024	va_list args;
2025
2026	ab = audit_log_start(ctx, gfp_mask, type);
2027	if (ab) {
2028		va_start(args, fmt);
2029		audit_log_vformat(ab, fmt, args);
2030		va_end(args);
2031		audit_log_end(ab);
2032	}
2033}
2034
2035#ifdef CONFIG_SECURITY
2036/**
2037 * audit_log_secctx - Converts and logs SELinux context
2038 * @ab: audit_buffer
2039 * @secid: security number
2040 *
2041 * This is a helper function that calls security_secid_to_secctx to convert
2042 * secid to secctx and then adds the (converted) SELinux context to the audit
2043 * log by calling audit_log_format, thus also preventing leak of internal secid
2044 * to userspace. If secid cannot be converted audit_panic is called.
2045 */
2046void audit_log_secctx(struct audit_buffer *ab, u32 secid)
2047{
2048	u32 len;
2049	char *secctx;
2050
2051	if (security_secid_to_secctx(secid, &secctx, &len)) {
2052		audit_panic("Cannot convert secid to context");
2053	} else {
2054		audit_log_format(ab, " obj=%s", secctx);
2055		security_release_secctx(secctx, len);
2056	}
2057}
2058EXPORT_SYMBOL(audit_log_secctx);
2059#endif
2060
2061EXPORT_SYMBOL(audit_log_start);
2062EXPORT_SYMBOL(audit_log_end);
2063EXPORT_SYMBOL(audit_log_format);
2064EXPORT_SYMBOL(audit_log);