linux/kernel/audit.c
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   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#include <linux/init.h>
  45#include <asm/types.h>
  46#include <linux/atomic.h>
  47#include <linux/mm.h>
  48#include <linux/export.h>
  49#include <linux/slab.h>
  50#include <linux/err.h>
  51#include <linux/kthread.h>
  52
  53#include <linux/audit.h>
  54
  55#include <net/sock.h>
  56#include <net/netlink.h>
  57#include <linux/skbuff.h>
  58#ifdef CONFIG_SECURITY
  59#include <linux/security.h>
  60#endif
  61#include <linux/netlink.h>
  62#include <linux/freezer.h>
  63#include <linux/tty.h>
  64
  65#include "audit.h"
  66
  67/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
  68 * (Initialization happens after skb_init is called.) */
  69#define AUDIT_DISABLED          -1
  70#define AUDIT_UNINITIALIZED     0
  71#define AUDIT_INITIALIZED       1
  72static int      audit_initialized;
  73
  74#define AUDIT_OFF       0
  75#define AUDIT_ON        1
  76#define AUDIT_LOCKED    2
  77int             audit_enabled;
  78int             audit_ever_enabled;
  79
  80EXPORT_SYMBOL_GPL(audit_enabled);
  81
  82/* Default state when kernel boots without any parameters. */
  83static int      audit_default;
  84
  85/* If auditing cannot proceed, audit_failure selects what happens. */
  86static int      audit_failure = AUDIT_FAIL_PRINTK;
  87
  88/*
  89 * If audit records are to be written to the netlink socket, audit_pid
  90 * contains the pid of the auditd process and audit_nlk_pid contains
  91 * the pid to use to send netlink messages to that process.
  92 */
  93int             audit_pid;
  94static int      audit_nlk_pid;
  95
  96/* If audit_rate_limit is non-zero, limit the rate of sending audit records
  97 * to that number per second.  This prevents DoS attacks, but results in
  98 * audit records being dropped. */
  99static int      audit_rate_limit;
 100
 101/* Number of outstanding audit_buffers allowed. */
 102static int      audit_backlog_limit = 64;
 103static int      audit_backlog_wait_time = 60 * HZ;
 104static int      audit_backlog_wait_overflow = 0;
 105
 106/* The identity of the user shutting down the audit system. */
 107uid_t           audit_sig_uid = -1;
 108pid_t           audit_sig_pid = -1;
 109u32             audit_sig_sid = 0;
 110
 111/* Records can be lost in several ways:
 112   0) [suppressed in audit_alloc]
 113   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
 114   2) out of memory in audit_log_move [alloc_skb]
 115   3) suppressed due to audit_rate_limit
 116   4) suppressed due to audit_backlog_limit
 117*/
 118static atomic_t    audit_lost = ATOMIC_INIT(0);
 119
 120/* The netlink socket. */
 121static struct sock *audit_sock;
 122
 123/* Hash for inode-based rules */
 124struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 125
 126/* The audit_freelist is a list of pre-allocated audit buffers (if more
 127 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
 128 * being placed on the freelist). */
 129static DEFINE_SPINLOCK(audit_freelist_lock);
 130static int         audit_freelist_count;
 131static LIST_HEAD(audit_freelist);
 132
 133static struct sk_buff_head audit_skb_queue;
 134/* queue of skbs to send to auditd when/if it comes back */
 135static struct sk_buff_head audit_skb_hold_queue;
 136static struct task_struct *kauditd_task;
 137static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 138static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 139
 140/* Serialize requests from userspace. */
 141DEFINE_MUTEX(audit_cmd_mutex);
 142
 143/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 144 * audit records.  Since printk uses a 1024 byte buffer, this buffer
 145 * should be at least that large. */
 146#define AUDIT_BUFSIZ 1024
 147
 148/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
 149 * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
 150#define AUDIT_MAXFREE  (2*NR_CPUS)
 151
 152/* The audit_buffer is used when formatting an audit record.  The caller
 153 * locks briefly to get the record off the freelist or to allocate the
 154 * buffer, and locks briefly to send the buffer to the netlink layer or
 155 * to place it on a transmit queue.  Multiple audit_buffers can be in
 156 * use simultaneously. */
 157struct audit_buffer {
 158        struct list_head     list;
 159        struct sk_buff       *skb;      /* formatted skb ready to send */
 160        struct audit_context *ctx;      /* NULL or associated context */
 161        gfp_t                gfp_mask;
 162};
 163
 164struct audit_reply {
 165        int pid;
 166        struct sk_buff *skb;
 167};
 168
 169static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
 170{
 171        if (ab) {
 172                struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
 173                nlh->nlmsg_pid = pid;
 174        }
 175}
 176
 177void audit_panic(const char *message)
 178{
 179        switch (audit_failure)
 180        {
 181        case AUDIT_FAIL_SILENT:
 182                break;
 183        case AUDIT_FAIL_PRINTK:
 184                if (printk_ratelimit())
 185                        printk(KERN_ERR "audit: %s\n", message);
 186                break;
 187        case AUDIT_FAIL_PANIC:
 188                /* test audit_pid since printk is always losey, why bother? */
 189                if (audit_pid)
 190                        panic("audit: %s\n", message);
 191                break;
 192        }
 193}
 194
 195static inline int audit_rate_check(void)
 196{
 197        static unsigned long    last_check = 0;
 198        static int              messages   = 0;
 199        static DEFINE_SPINLOCK(lock);
 200        unsigned long           flags;
 201        unsigned long           now;
 202        unsigned long           elapsed;
 203        int                     retval     = 0;
 204
 205        if (!audit_rate_limit) return 1;
 206
 207        spin_lock_irqsave(&lock, flags);
 208        if (++messages < audit_rate_limit) {
 209                retval = 1;
 210        } else {
 211                now     = jiffies;
 212                elapsed = now - last_check;
 213                if (elapsed > HZ) {
 214                        last_check = now;
 215                        messages   = 0;
 216                        retval     = 1;
 217                }
 218        }
 219        spin_unlock_irqrestore(&lock, flags);
 220
 221        return retval;
 222}
 223
 224/**
 225 * audit_log_lost - conditionally log lost audit message event
 226 * @message: the message stating reason for lost audit message
 227 *
 228 * Emit at least 1 message per second, even if audit_rate_check is
 229 * throttling.
 230 * Always increment the lost messages counter.
 231*/
 232void audit_log_lost(const char *message)
 233{
 234        static unsigned long    last_msg = 0;
 235        static DEFINE_SPINLOCK(lock);
 236        unsigned long           flags;
 237        unsigned long           now;
 238        int                     print;
 239
 240        atomic_inc(&audit_lost);
 241
 242        print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 243
 244        if (!print) {
 245                spin_lock_irqsave(&lock, flags);
 246                now = jiffies;
 247                if (now - last_msg > HZ) {
 248                        print = 1;
 249                        last_msg = now;
 250                }
 251                spin_unlock_irqrestore(&lock, flags);
 252        }
 253
 254        if (print) {
 255                if (printk_ratelimit())
 256                        printk(KERN_WARNING
 257                                "audit: audit_lost=%d audit_rate_limit=%d "
 258                                "audit_backlog_limit=%d\n",
 259                                atomic_read(&audit_lost),
 260                                audit_rate_limit,
 261                                audit_backlog_limit);
 262                audit_panic(message);
 263        }
 264}
 265
 266static int audit_log_config_change(char *function_name, int new, int old,
 267                                   uid_t loginuid, u32 sessionid, u32 sid,
 268                                   int allow_changes)
 269{
 270        struct audit_buffer *ab;
 271        int rc = 0;
 272
 273        ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 274        audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
 275                         old, loginuid, sessionid);
 276        if (sid) {
 277                char *ctx = NULL;
 278                u32 len;
 279
 280                rc = security_secid_to_secctx(sid, &ctx, &len);
 281                if (rc) {
 282                        audit_log_format(ab, " sid=%u", sid);
 283                        allow_changes = 0; /* Something weird, deny request */
 284                } else {
 285                        audit_log_format(ab, " subj=%s", ctx);
 286                        security_release_secctx(ctx, len);
 287                }
 288        }
 289        audit_log_format(ab, " res=%d", allow_changes);
 290        audit_log_end(ab);
 291        return rc;
 292}
 293
 294static int audit_do_config_change(char *function_name, int *to_change,
 295                                  int new, uid_t loginuid, u32 sessionid,
 296                                  u32 sid)
 297{
 298        int allow_changes, rc = 0, old = *to_change;
 299
 300        /* check if we are locked */
 301        if (audit_enabled == AUDIT_LOCKED)
 302                allow_changes = 0;
 303        else
 304                allow_changes = 1;
 305
 306        if (audit_enabled != AUDIT_OFF) {
 307                rc = audit_log_config_change(function_name, new, old, loginuid,
 308                                             sessionid, sid, allow_changes);
 309                if (rc)
 310                        allow_changes = 0;
 311        }
 312
 313        /* If we are allowed, make the change */
 314        if (allow_changes == 1)
 315                *to_change = new;
 316        /* Not allowed, update reason */
 317        else if (rc == 0)
 318                rc = -EPERM;
 319        return rc;
 320}
 321
 322static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
 323                                u32 sid)
 324{
 325        return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
 326                                      limit, loginuid, sessionid, sid);
 327}
 328
 329static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
 330                                   u32 sid)
 331{
 332        return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
 333                                      limit, loginuid, sessionid, sid);
 334}
 335
 336static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
 337{
 338        int rc;
 339        if (state < AUDIT_OFF || state > AUDIT_LOCKED)
 340                return -EINVAL;
 341
 342        rc =  audit_do_config_change("audit_enabled", &audit_enabled, state,
 343                                     loginuid, sessionid, sid);
 344
 345        if (!rc)
 346                audit_ever_enabled |= !!state;
 347
 348        return rc;
 349}
 350
 351static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
 352{
 353        if (state != AUDIT_FAIL_SILENT
 354            && state != AUDIT_FAIL_PRINTK
 355            && state != AUDIT_FAIL_PANIC)
 356                return -EINVAL;
 357
 358        return audit_do_config_change("audit_failure", &audit_failure, state,
 359                                      loginuid, sessionid, sid);
 360}
 361
 362/*
 363 * Queue skbs to be sent to auditd when/if it comes back.  These skbs should
 364 * already have been sent via prink/syslog and so if these messages are dropped
 365 * it is not a huge concern since we already passed the audit_log_lost()
 366 * notification and stuff.  This is just nice to get audit messages during
 367 * boot before auditd is running or messages generated while auditd is stopped.
 368 * This only holds messages is audit_default is set, aka booting with audit=1
 369 * or building your kernel that way.
 370 */
 371static void audit_hold_skb(struct sk_buff *skb)
 372{
 373        if (audit_default &&
 374            skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
 375                skb_queue_tail(&audit_skb_hold_queue, skb);
 376        else
 377                kfree_skb(skb);
 378}
 379
 380/*
 381 * For one reason or another this nlh isn't getting delivered to the userspace
 382 * audit daemon, just send it to printk.
 383 */
 384static void audit_printk_skb(struct sk_buff *skb)
 385{
 386        struct nlmsghdr *nlh = nlmsg_hdr(skb);
 387        char *data = NLMSG_DATA(nlh);
 388
 389        if (nlh->nlmsg_type != AUDIT_EOE) {
 390                if (printk_ratelimit())
 391                        printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
 392                else
 393                        audit_log_lost("printk limit exceeded\n");
 394        }
 395
 396        audit_hold_skb(skb);
 397}
 398
 399static void kauditd_send_skb(struct sk_buff *skb)
 400{
 401        int err;
 402        /* take a reference in case we can't send it and we want to hold it */
 403        skb_get(skb);
 404        err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
 405        if (err < 0) {
 406                BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
 407                printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
 408                audit_log_lost("auditd disappeared\n");
 409                audit_pid = 0;
 410                /* we might get lucky and get this in the next auditd */
 411                audit_hold_skb(skb);
 412        } else
 413                /* drop the extra reference if sent ok */
 414                consume_skb(skb);
 415}
 416
 417static int kauditd_thread(void *dummy)
 418{
 419        struct sk_buff *skb;
 420
 421        set_freezable();
 422        while (!kthread_should_stop()) {
 423                /*
 424                 * if auditd just started drain the queue of messages already
 425                 * sent to syslog/printk.  remember loss here is ok.  we already
 426                 * called audit_log_lost() if it didn't go out normally.  so the
 427                 * race between the skb_dequeue and the next check for audit_pid
 428                 * doesn't matter.
 429                 *
 430                 * if you ever find kauditd to be too slow we can get a perf win
 431                 * by doing our own locking and keeping better track if there
 432                 * are messages in this queue.  I don't see the need now, but
 433                 * in 5 years when I want to play with this again I'll see this
 434                 * note and still have no friggin idea what i'm thinking today.
 435                 */
 436                if (audit_default && audit_pid) {
 437                        skb = skb_dequeue(&audit_skb_hold_queue);
 438                        if (unlikely(skb)) {
 439                                while (skb && audit_pid) {
 440                                        kauditd_send_skb(skb);
 441                                        skb = skb_dequeue(&audit_skb_hold_queue);
 442                                }
 443                        }
 444                }
 445
 446                skb = skb_dequeue(&audit_skb_queue);
 447                wake_up(&audit_backlog_wait);
 448                if (skb) {
 449                        if (audit_pid)
 450                                kauditd_send_skb(skb);
 451                        else
 452                                audit_printk_skb(skb);
 453                } else {
 454                        DECLARE_WAITQUEUE(wait, current);
 455                        set_current_state(TASK_INTERRUPTIBLE);
 456                        add_wait_queue(&kauditd_wait, &wait);
 457
 458                        if (!skb_queue_len(&audit_skb_queue)) {
 459                                try_to_freeze();
 460                                schedule();
 461                        }
 462
 463                        __set_current_state(TASK_RUNNING);
 464                        remove_wait_queue(&kauditd_wait, &wait);
 465                }
 466        }
 467        return 0;
 468}
 469
 470static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
 471{
 472        struct task_struct *tsk;
 473        int err;
 474
 475        rcu_read_lock();
 476        tsk = find_task_by_vpid(pid);
 477        if (!tsk) {
 478                rcu_read_unlock();
 479                return -ESRCH;
 480        }
 481        get_task_struct(tsk);
 482        rcu_read_unlock();
 483        err = tty_audit_push_task(tsk, loginuid, sessionid);
 484        put_task_struct(tsk);
 485        return err;
 486}
 487
 488int audit_send_list(void *_dest)
 489{
 490        struct audit_netlink_list *dest = _dest;
 491        int pid = dest->pid;
 492        struct sk_buff *skb;
 493
 494        /* wait for parent to finish and send an ACK */
 495        mutex_lock(&audit_cmd_mutex);
 496        mutex_unlock(&audit_cmd_mutex);
 497
 498        while ((skb = __skb_dequeue(&dest->q)) != NULL)
 499                netlink_unicast(audit_sock, skb, pid, 0);
 500
 501        kfree(dest);
 502
 503        return 0;
 504}
 505
 506struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
 507                                 int multi, const void *payload, int size)
 508{
 509        struct sk_buff  *skb;
 510        struct nlmsghdr *nlh;
 511        void            *data;
 512        int             flags = multi ? NLM_F_MULTI : 0;
 513        int             t     = done  ? NLMSG_DONE  : type;
 514
 515        skb = nlmsg_new(size, GFP_KERNEL);
 516        if (!skb)
 517                return NULL;
 518
 519        nlh     = NLMSG_NEW(skb, pid, seq, t, size, flags);
 520        data    = NLMSG_DATA(nlh);
 521        memcpy(data, payload, size);
 522        return skb;
 523
 524nlmsg_failure:                  /* Used by NLMSG_NEW */
 525        if (skb)
 526                kfree_skb(skb);
 527        return NULL;
 528}
 529
 530static int audit_send_reply_thread(void *arg)
 531{
 532        struct audit_reply *reply = (struct audit_reply *)arg;
 533
 534        mutex_lock(&audit_cmd_mutex);
 535        mutex_unlock(&audit_cmd_mutex);
 536
 537        /* Ignore failure. It'll only happen if the sender goes away,
 538           because our timeout is set to infinite. */
 539        netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
 540        kfree(reply);
 541        return 0;
 542}
 543/**
 544 * audit_send_reply - send an audit reply message via netlink
 545 * @pid: process id to send reply to
 546 * @seq: sequence number
 547 * @type: audit message type
 548 * @done: done (last) flag
 549 * @multi: multi-part message flag
 550 * @payload: payload data
 551 * @size: payload size
 552 *
 553 * Allocates an skb, builds the netlink message, and sends it to the pid.
 554 * No failure notifications.
 555 */
 556static void audit_send_reply(int pid, int seq, int type, int done, int multi,
 557                             const void *payload, int size)
 558{
 559        struct sk_buff *skb;
 560        struct task_struct *tsk;
 561        struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
 562                                            GFP_KERNEL);
 563
 564        if (!reply)
 565                return;
 566
 567        skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
 568        if (!skb)
 569                goto out;
 570
 571        reply->pid = pid;
 572        reply->skb = skb;
 573
 574        tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
 575        if (!IS_ERR(tsk))
 576                return;
 577        kfree_skb(skb);
 578out:
 579        kfree(reply);
 580}
 581
 582/*
 583 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 584 * control messages.
 585 */
 586static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 587{
 588        int err = 0;
 589
 590        switch (msg_type) {
 591        case AUDIT_GET:
 592        case AUDIT_LIST:
 593        case AUDIT_LIST_RULES:
 594        case AUDIT_SET:
 595        case AUDIT_ADD:
 596        case AUDIT_ADD_RULE:
 597        case AUDIT_DEL:
 598        case AUDIT_DEL_RULE:
 599        case AUDIT_SIGNAL_INFO:
 600        case AUDIT_TTY_GET:
 601        case AUDIT_TTY_SET:
 602        case AUDIT_TRIM:
 603        case AUDIT_MAKE_EQUIV:
 604                if (!capable(CAP_AUDIT_CONTROL))
 605                        err = -EPERM;
 606                break;
 607        case AUDIT_USER:
 608        case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 609        case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 610                if (!capable(CAP_AUDIT_WRITE))
 611                        err = -EPERM;
 612                break;
 613        default:  /* bad msg */
 614                err = -EINVAL;
 615        }
 616
 617        return err;
 618}
 619
 620static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
 621                                     u32 pid, u32 uid, uid_t auid, u32 ses,
 622                                     u32 sid)
 623{
 624        int rc = 0;
 625        char *ctx = NULL;
 626        u32 len;
 627
 628        if (!audit_enabled) {
 629                *ab = NULL;
 630                return rc;
 631        }
 632
 633        *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 634        audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
 635                         pid, uid, auid, ses);
 636        if (sid) {
 637                rc = security_secid_to_secctx(sid, &ctx, &len);
 638                if (rc)
 639                        audit_log_format(*ab, " ssid=%u", sid);
 640                else {
 641                        audit_log_format(*ab, " subj=%s", ctx);
 642                        security_release_secctx(ctx, len);
 643                }
 644        }
 645
 646        return rc;
 647}
 648
 649static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 650{
 651        u32                     uid, pid, seq, sid;
 652        void                    *data;
 653        struct audit_status     *status_get, status_set;
 654        int                     err;
 655        struct audit_buffer     *ab;
 656        u16                     msg_type = nlh->nlmsg_type;
 657        uid_t                   loginuid; /* loginuid of sender */
 658        u32                     sessionid;
 659        struct audit_sig_info   *sig_data;
 660        char                    *ctx = NULL;
 661        u32                     len;
 662
 663        err = audit_netlink_ok(skb, msg_type);
 664        if (err)
 665                return err;
 666
 667        /* As soon as there's any sign of userspace auditd,
 668         * start kauditd to talk to it */
 669        if (!kauditd_task)
 670                kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 671        if (IS_ERR(kauditd_task)) {
 672                err = PTR_ERR(kauditd_task);
 673                kauditd_task = NULL;
 674                return err;
 675        }
 676
 677        pid  = NETLINK_CREDS(skb)->pid;
 678        uid  = NETLINK_CREDS(skb)->uid;
 679        loginuid = audit_get_loginuid(current);
 680        sessionid = audit_get_sessionid(current);
 681        security_task_getsecid(current, &sid);
 682        seq  = nlh->nlmsg_seq;
 683        data = NLMSG_DATA(nlh);
 684
 685        switch (msg_type) {
 686        case AUDIT_GET:
 687                status_set.enabled       = audit_enabled;
 688                status_set.failure       = audit_failure;
 689                status_set.pid           = audit_pid;
 690                status_set.rate_limit    = audit_rate_limit;
 691                status_set.backlog_limit = audit_backlog_limit;
 692                status_set.lost          = atomic_read(&audit_lost);
 693                status_set.backlog       = skb_queue_len(&audit_skb_queue);
 694                audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
 695                                 &status_set, sizeof(status_set));
 696                break;
 697        case AUDIT_SET:
 698                if (nlh->nlmsg_len < sizeof(struct audit_status))
 699                        return -EINVAL;
 700                status_get   = (struct audit_status *)data;
 701                if (status_get->mask & AUDIT_STATUS_ENABLED) {
 702                        err = audit_set_enabled(status_get->enabled,
 703                                                loginuid, sessionid, sid);
 704                        if (err < 0)
 705                                return err;
 706                }
 707                if (status_get->mask & AUDIT_STATUS_FAILURE) {
 708                        err = audit_set_failure(status_get->failure,
 709                                                loginuid, sessionid, sid);
 710                        if (err < 0)
 711                                return err;
 712                }
 713                if (status_get->mask & AUDIT_STATUS_PID) {
 714                        int new_pid = status_get->pid;
 715
 716                        if (audit_enabled != AUDIT_OFF)
 717                                audit_log_config_change("audit_pid", new_pid,
 718                                                        audit_pid, loginuid,
 719                                                        sessionid, sid, 1);
 720
 721                        audit_pid = new_pid;
 722                        audit_nlk_pid = NETLINK_CB(skb).pid;
 723                }
 724                if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
 725                        err = audit_set_rate_limit(status_get->rate_limit,
 726                                                   loginuid, sessionid, sid);
 727                        if (err < 0)
 728                                return err;
 729                }
 730                if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
 731                        err = audit_set_backlog_limit(status_get->backlog_limit,
 732                                                      loginuid, sessionid, sid);
 733                break;
 734        case AUDIT_USER:
 735        case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 736        case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 737                if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 738                        return 0;
 739
 740                err = audit_filter_user(&NETLINK_CB(skb));
 741                if (err == 1) {
 742                        err = 0;
 743                        if (msg_type == AUDIT_USER_TTY) {
 744                                err = audit_prepare_user_tty(pid, loginuid,
 745                                                             sessionid);
 746                                if (err)
 747                                        break;
 748                        }
 749                        audit_log_common_recv_msg(&ab, msg_type, pid, uid,
 750                                                  loginuid, sessionid, sid);
 751
 752                        if (msg_type != AUDIT_USER_TTY)
 753                                audit_log_format(ab, " msg='%.1024s'",
 754                                                 (char *)data);
 755                        else {
 756                                int size;
 757
 758                                audit_log_format(ab, " msg=");
 759                                size = nlmsg_len(nlh);
 760                                if (size > 0 &&
 761                                    ((unsigned char *)data)[size - 1] == '\0')
 762                                        size--;
 763                                audit_log_n_untrustedstring(ab, data, size);
 764                        }
 765                        audit_set_pid(ab, pid);
 766                        audit_log_end(ab);
 767                }
 768                break;
 769        case AUDIT_ADD:
 770        case AUDIT_DEL:
 771                if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 772                        return -EINVAL;
 773                if (audit_enabled == AUDIT_LOCKED) {
 774                        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 775                                                  uid, loginuid, sessionid, sid);
 776
 777                        audit_log_format(ab, " audit_enabled=%d res=0",
 778                                         audit_enabled);
 779                        audit_log_end(ab);
 780                        return -EPERM;
 781                }
 782                /* fallthrough */
 783        case AUDIT_LIST:
 784                err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
 785                                           uid, seq, data, nlmsg_len(nlh),
 786                                           loginuid, sessionid, sid);
 787                break;
 788        case AUDIT_ADD_RULE:
 789        case AUDIT_DEL_RULE:
 790                if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 791                        return -EINVAL;
 792                if (audit_enabled == AUDIT_LOCKED) {
 793                        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 794                                                  uid, loginuid, sessionid, sid);
 795
 796                        audit_log_format(ab, " audit_enabled=%d res=0",
 797                                         audit_enabled);
 798                        audit_log_end(ab);
 799                        return -EPERM;
 800                }
 801                /* fallthrough */
 802        case AUDIT_LIST_RULES:
 803                err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
 804                                           uid, seq, data, nlmsg_len(nlh),
 805                                           loginuid, sessionid, sid);
 806                break;
 807        case AUDIT_TRIM:
 808                audit_trim_trees();
 809
 810                audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 811                                          uid, loginuid, sessionid, sid);
 812
 813                audit_log_format(ab, " op=trim res=1");
 814                audit_log_end(ab);
 815                break;
 816        case AUDIT_MAKE_EQUIV: {
 817                void *bufp = data;
 818                u32 sizes[2];
 819                size_t msglen = nlmsg_len(nlh);
 820                char *old, *new;
 821
 822                err = -EINVAL;
 823                if (msglen < 2 * sizeof(u32))
 824                        break;
 825                memcpy(sizes, bufp, 2 * sizeof(u32));
 826                bufp += 2 * sizeof(u32);
 827                msglen -= 2 * sizeof(u32);
 828                old = audit_unpack_string(&bufp, &msglen, sizes[0]);
 829                if (IS_ERR(old)) {
 830                        err = PTR_ERR(old);
 831                        break;
 832                }
 833                new = audit_unpack_string(&bufp, &msglen, sizes[1]);
 834                if (IS_ERR(new)) {
 835                        err = PTR_ERR(new);
 836                        kfree(old);
 837                        break;
 838                }
 839                /* OK, here comes... */
 840                err = audit_tag_tree(old, new);
 841
 842                audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 843                                          uid, loginuid, sessionid, sid);
 844
 845                audit_log_format(ab, " op=make_equiv old=");
 846                audit_log_untrustedstring(ab, old);
 847                audit_log_format(ab, " new=");
 848                audit_log_untrustedstring(ab, new);
 849                audit_log_format(ab, " res=%d", !err);
 850                audit_log_end(ab);
 851                kfree(old);
 852                kfree(new);
 853                break;
 854        }
 855        case AUDIT_SIGNAL_INFO:
 856                len = 0;
 857                if (audit_sig_sid) {
 858                        err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
 859                        if (err)
 860                                return err;
 861                }
 862                sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 863                if (!sig_data) {
 864                        if (audit_sig_sid)
 865                                security_release_secctx(ctx, len);
 866                        return -ENOMEM;
 867                }
 868                sig_data->uid = audit_sig_uid;
 869                sig_data->pid = audit_sig_pid;
 870                if (audit_sig_sid) {
 871                        memcpy(sig_data->ctx, ctx, len);
 872                        security_release_secctx(ctx, len);
 873                }
 874                audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
 875                                0, 0, sig_data, sizeof(*sig_data) + len);
 876                kfree(sig_data);
 877                break;
 878        case AUDIT_TTY_GET: {
 879                struct audit_tty_status s;
 880                struct task_struct *tsk;
 881                unsigned long flags;
 882
 883                rcu_read_lock();
 884                tsk = find_task_by_vpid(pid);
 885                if (tsk && lock_task_sighand(tsk, &flags)) {
 886                        s.enabled = tsk->signal->audit_tty != 0;
 887                        unlock_task_sighand(tsk, &flags);
 888                } else
 889                        err = -ESRCH;
 890                rcu_read_unlock();
 891
 892                if (!err)
 893                        audit_send_reply(NETLINK_CB(skb).pid, seq,
 894                                         AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
 895                break;
 896        }
 897        case AUDIT_TTY_SET: {
 898                struct audit_tty_status *s;
 899                struct task_struct *tsk;
 900                unsigned long flags;
 901
 902                if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
 903                        return -EINVAL;
 904                s = data;
 905                if (s->enabled != 0 && s->enabled != 1)
 906                        return -EINVAL;
 907                rcu_read_lock();
 908                tsk = find_task_by_vpid(pid);
 909                if (tsk && lock_task_sighand(tsk, &flags)) {
 910                        tsk->signal->audit_tty = s->enabled != 0;
 911                        unlock_task_sighand(tsk, &flags);
 912                } else
 913                        err = -ESRCH;
 914                rcu_read_unlock();
 915                break;
 916        }
 917        default:
 918                err = -EINVAL;
 919                break;
 920        }
 921
 922        return err < 0 ? err : 0;
 923}
 924
 925/*
 926 * Get message from skb.  Each message is processed by audit_receive_msg.
 927 * Malformed skbs with wrong length are discarded silently.
 928 */
 929static void audit_receive_skb(struct sk_buff *skb)
 930{
 931        struct nlmsghdr *nlh;
 932        /*
 933         * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
 934         * if the nlmsg_len was not aligned
 935         */
 936        int len;
 937        int err;
 938
 939        nlh = nlmsg_hdr(skb);
 940        len = skb->len;
 941
 942        while (NLMSG_OK(nlh, len)) {
 943                err = audit_receive_msg(skb, nlh);
 944                /* if err or if this message says it wants a response */
 945                if (err || (nlh->nlmsg_flags & NLM_F_ACK))
 946                        netlink_ack(skb, nlh, err);
 947
 948                nlh = NLMSG_NEXT(nlh, len);
 949        }
 950}
 951
 952/* Receive messages from netlink socket. */
 953static void audit_receive(struct sk_buff  *skb)
 954{
 955        mutex_lock(&audit_cmd_mutex);
 956        audit_receive_skb(skb);
 957        mutex_unlock(&audit_cmd_mutex);
 958}
 959
 960/* Initialize audit support at boot time. */
 961static int __init audit_init(void)
 962{
 963        int i;
 964
 965        if (audit_initialized == AUDIT_DISABLED)
 966                return 0;
 967
 968        printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
 969               audit_default ? "enabled" : "disabled");
 970        audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
 971                                           audit_receive, NULL, THIS_MODULE);
 972        if (!audit_sock)
 973                audit_panic("cannot initialize netlink socket");
 974        else
 975                audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
 976
 977        skb_queue_head_init(&audit_skb_queue);
 978        skb_queue_head_init(&audit_skb_hold_queue);
 979        audit_initialized = AUDIT_INITIALIZED;
 980        audit_enabled = audit_default;
 981        audit_ever_enabled |= !!audit_default;
 982
 983        audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
 984
 985        for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
 986                INIT_LIST_HEAD(&audit_inode_hash[i]);
 987
 988        return 0;
 989}
 990__initcall(audit_init);
 991
 992/* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
 993static int __init audit_enable(char *str)
 994{
 995        audit_default = !!simple_strtol(str, NULL, 0);
 996        if (!audit_default)
 997                audit_initialized = AUDIT_DISABLED;
 998
 999        printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
1000
1001        if (audit_initialized == AUDIT_INITIALIZED) {
1002                audit_enabled = audit_default;
1003                audit_ever_enabled |= !!audit_default;
1004        } else if (audit_initialized == AUDIT_UNINITIALIZED) {
1005                printk(" (after initialization)");
1006        } else {
1007                printk(" (until reboot)");
1008        }
1009        printk("\n");
1010
1011        return 1;
1012}
1013
1014__setup("audit=", audit_enable);
1015
1016static void audit_buffer_free(struct audit_buffer *ab)
1017{
1018        unsigned long flags;
1019
1020        if (!ab)
1021                return;
1022
1023        if (ab->skb)
1024                kfree_skb(ab->skb);
1025
1026        spin_lock_irqsave(&audit_freelist_lock, flags);
1027        if (audit_freelist_count > AUDIT_MAXFREE)
1028                kfree(ab);
1029        else {
1030                audit_freelist_count++;
1031                list_add(&ab->list, &audit_freelist);
1032        }
1033        spin_unlock_irqrestore(&audit_freelist_lock, flags);
1034}
1035
1036static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1037                                                gfp_t gfp_mask, int type)
1038{
1039        unsigned long flags;
1040        struct audit_buffer *ab = NULL;
1041        struct nlmsghdr *nlh;
1042
1043        spin_lock_irqsave(&audit_freelist_lock, flags);
1044        if (!list_empty(&audit_freelist)) {
1045                ab = list_entry(audit_freelist.next,
1046                                struct audit_buffer, list);
1047                list_del(&ab->list);
1048                --audit_freelist_count;
1049        }
1050        spin_unlock_irqrestore(&audit_freelist_lock, flags);
1051
1052        if (!ab) {
1053                ab = kmalloc(sizeof(*ab), gfp_mask);
1054                if (!ab)
1055                        goto err;
1056        }
1057
1058        ab->ctx = ctx;
1059        ab->gfp_mask = gfp_mask;
1060
1061        ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1062        if (!ab->skb)
1063                goto nlmsg_failure;
1064
1065        nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0);
1066
1067        return ab;
1068
1069nlmsg_failure:                  /* Used by NLMSG_NEW */
1070        kfree_skb(ab->skb);
1071        ab->skb = NULL;
1072err:
1073        audit_buffer_free(ab);
1074        return NULL;
1075}
1076
1077/**
1078 * audit_serial - compute a serial number for the audit record
1079 *
1080 * Compute a serial number for the audit record.  Audit records are
1081 * written to user-space as soon as they are generated, so a complete
1082 * audit record may be written in several pieces.  The timestamp of the
1083 * record and this serial number are used by the user-space tools to
1084 * determine which pieces belong to the same audit record.  The
1085 * (timestamp,serial) tuple is unique for each syscall and is live from
1086 * syscall entry to syscall exit.
1087 *
1088 * NOTE: Another possibility is to store the formatted records off the
1089 * audit context (for those records that have a context), and emit them
1090 * all at syscall exit.  However, this could delay the reporting of
1091 * significant errors until syscall exit (or never, if the system
1092 * halts).
1093 */
1094unsigned int audit_serial(void)
1095{
1096        static DEFINE_SPINLOCK(serial_lock);
1097        static unsigned int serial = 0;
1098
1099        unsigned long flags;
1100        unsigned int ret;
1101
1102        spin_lock_irqsave(&serial_lock, flags);
1103        do {
1104                ret = ++serial;
1105        } while (unlikely(!ret));
1106        spin_unlock_irqrestore(&serial_lock, flags);
1107
1108        return ret;
1109}
1110
1111static inline void audit_get_stamp(struct audit_context *ctx,
1112                                   struct timespec *t, unsigned int *serial)
1113{
1114        if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1115                *t = CURRENT_TIME;
1116                *serial = audit_serial();
1117        }
1118}
1119
1120/* Obtain an audit buffer.  This routine does locking to obtain the
1121 * audit buffer, but then no locking is required for calls to
1122 * audit_log_*format.  If the tsk is a task that is currently in a
1123 * syscall, then the syscall is marked as auditable and an audit record
1124 * will be written at syscall exit.  If there is no associated task, tsk
1125 * should be NULL. */
1126
1127/**
1128 * audit_log_start - obtain an audit buffer
1129 * @ctx: audit_context (may be NULL)
1130 * @gfp_mask: type of allocation
1131 * @type: audit message type
1132 *
1133 * Returns audit_buffer pointer on success or NULL on error.
1134 *
1135 * Obtain an audit buffer.  This routine does locking to obtain the
1136 * audit buffer, but then no locking is required for calls to
1137 * audit_log_*format.  If the task (ctx) is a task that is currently in a
1138 * syscall, then the syscall is marked as auditable and an audit record
1139 * will be written at syscall exit.  If there is no associated task, then
1140 * task context (ctx) should be NULL.
1141 */
1142struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1143                                     int type)
1144{
1145        struct audit_buffer     *ab     = NULL;
1146        struct timespec         t;
1147        unsigned int            uninitialized_var(serial);
1148        int reserve;
1149        unsigned long timeout_start = jiffies;
1150
1151        if (audit_initialized != AUDIT_INITIALIZED)
1152                return NULL;
1153
1154        if (unlikely(audit_filter_type(type)))
1155                return NULL;
1156
1157        if (gfp_mask & __GFP_WAIT)
1158                reserve = 0;
1159        else
1160                reserve = 5; /* Allow atomic callers to go up to five
1161                                entries over the normal backlog limit */
1162
1163        while (audit_backlog_limit
1164               && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1165                if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1166                    && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1167
1168                        /* Wait for auditd to drain the queue a little */
1169                        DECLARE_WAITQUEUE(wait, current);
1170                        set_current_state(TASK_INTERRUPTIBLE);
1171                        add_wait_queue(&audit_backlog_wait, &wait);
1172
1173                        if (audit_backlog_limit &&
1174                            skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1175                                schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1176
1177                        __set_current_state(TASK_RUNNING);
1178                        remove_wait_queue(&audit_backlog_wait, &wait);
1179                        continue;
1180                }
1181                if (audit_rate_check() && printk_ratelimit())
1182                        printk(KERN_WARNING
1183                               "audit: audit_backlog=%d > "
1184                               "audit_backlog_limit=%d\n",
1185                               skb_queue_len(&audit_skb_queue),
1186                               audit_backlog_limit);
1187                audit_log_lost("backlog limit exceeded");
1188                audit_backlog_wait_time = audit_backlog_wait_overflow;
1189                wake_up(&audit_backlog_wait);
1190                return NULL;
1191        }
1192
1193        ab = audit_buffer_alloc(ctx, gfp_mask, type);
1194        if (!ab) {
1195                audit_log_lost("out of memory in audit_log_start");
1196                return NULL;
1197        }
1198
1199        audit_get_stamp(ab->ctx, &t, &serial);
1200
1201        audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1202                         t.tv_sec, t.tv_nsec/1000000, serial);
1203        return ab;
1204}
1205
1206/**
1207 * audit_expand - expand skb in the audit buffer
1208 * @ab: audit_buffer
1209 * @extra: space to add at tail of the skb
1210 *
1211 * Returns 0 (no space) on failed expansion, or available space if
1212 * successful.
1213 */
1214static inline int audit_expand(struct audit_buffer *ab, int extra)
1215{
1216        struct sk_buff *skb = ab->skb;
1217        int oldtail = skb_tailroom(skb);
1218        int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1219        int newtail = skb_tailroom(skb);
1220
1221        if (ret < 0) {
1222                audit_log_lost("out of memory in audit_expand");
1223                return 0;
1224        }
1225
1226        skb->truesize += newtail - oldtail;
1227        return newtail;
1228}
1229
1230/*
1231 * Format an audit message into the audit buffer.  If there isn't enough
1232 * room in the audit buffer, more room will be allocated and vsnprint
1233 * will be called a second time.  Currently, we assume that a printk
1234 * can't format message larger than 1024 bytes, so we don't either.
1235 */
1236static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1237                              va_list args)
1238{
1239        int len, avail;
1240        struct sk_buff *skb;
1241        va_list args2;
1242
1243        if (!ab)
1244                return;
1245
1246        BUG_ON(!ab->skb);
1247        skb = ab->skb;
1248        avail = skb_tailroom(skb);
1249        if (avail == 0) {
1250                avail = audit_expand(ab, AUDIT_BUFSIZ);
1251                if (!avail)
1252                        goto out;
1253        }
1254        va_copy(args2, args);
1255        len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1256        if (len >= avail) {
1257                /* The printk buffer is 1024 bytes long, so if we get
1258                 * here and AUDIT_BUFSIZ is at least 1024, then we can
1259                 * log everything that printk could have logged. */
1260                avail = audit_expand(ab,
1261                        max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1262                if (!avail)
1263                        goto out_va_end;
1264                len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1265        }
1266        if (len > 0)
1267                skb_put(skb, len);
1268out_va_end:
1269        va_end(args2);
1270out:
1271        return;
1272}
1273
1274/**
1275 * audit_log_format - format a message into the audit buffer.
1276 * @ab: audit_buffer
1277 * @fmt: format string
1278 * @...: optional parameters matching @fmt string
1279 *
1280 * All the work is done in audit_log_vformat.
1281 */
1282void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1283{
1284        va_list args;
1285
1286        if (!ab)
1287                return;
1288        va_start(args, fmt);
1289        audit_log_vformat(ab, fmt, args);
1290        va_end(args);
1291}
1292
1293/**
1294 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1295 * @ab: the audit_buffer
1296 * @buf: buffer to convert to hex
1297 * @len: length of @buf to be converted
1298 *
1299 * No return value; failure to expand is silently ignored.
1300 *
1301 * This function will take the passed buf and convert it into a string of
1302 * ascii hex digits. The new string is placed onto the skb.
1303 */
1304void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1305                size_t len)
1306{
1307        int i, avail, new_len;
1308        unsigned char *ptr;
1309        struct sk_buff *skb;
1310        static const unsigned char *hex = "0123456789ABCDEF";
1311
1312        if (!ab)
1313                return;
1314
1315        BUG_ON(!ab->skb);
1316        skb = ab->skb;
1317        avail = skb_tailroom(skb);
1318        new_len = len<<1;
1319        if (new_len >= avail) {
1320                /* Round the buffer request up to the next multiple */
1321                new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1322                avail = audit_expand(ab, new_len);
1323                if (!avail)
1324                        return;
1325        }
1326
1327        ptr = skb_tail_pointer(skb);
1328        for (i=0; i<len; i++) {
1329                *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1330                *ptr++ = hex[buf[i] & 0x0F];      /* Lower nibble */
1331        }
1332        *ptr = 0;
1333        skb_put(skb, len << 1); /* new string is twice the old string */
1334}
1335
1336/*
1337 * Format a string of no more than slen characters into the audit buffer,
1338 * enclosed in quote marks.
1339 */
1340void audit_log_n_string(struct audit_buffer *ab, const char *string,
1341                        size_t slen)
1342{
1343        int avail, new_len;
1344        unsigned char *ptr;
1345        struct sk_buff *skb;
1346
1347        if (!ab)
1348                return;
1349
1350        BUG_ON(!ab->skb);
1351        skb = ab->skb;
1352        avail = skb_tailroom(skb);
1353        new_len = slen + 3;     /* enclosing quotes + null terminator */
1354        if (new_len > avail) {
1355                avail = audit_expand(ab, new_len);
1356                if (!avail)
1357                        return;
1358        }
1359        ptr = skb_tail_pointer(skb);
1360        *ptr++ = '"';
1361        memcpy(ptr, string, slen);
1362        ptr += slen;
1363        *ptr++ = '"';
1364        *ptr = 0;
1365        skb_put(skb, slen + 2); /* don't include null terminator */
1366}
1367
1368/**
1369 * audit_string_contains_control - does a string need to be logged in hex
1370 * @string: string to be checked
1371 * @len: max length of the string to check
1372 */
1373int audit_string_contains_control(const char *string, size_t len)
1374{
1375        const unsigned char *p;
1376        for (p = string; p < (const unsigned char *)string + len; p++) {
1377                if (*p == '"' || *p < 0x21 || *p > 0x7e)
1378                        return 1;
1379        }
1380        return 0;
1381}
1382
1383/**
1384 * audit_log_n_untrustedstring - log a string that may contain random characters
1385 * @ab: audit_buffer
1386 * @len: length of string (not including trailing null)
1387 * @string: string to be logged
1388 *
1389 * This code will escape a string that is passed to it if the string
1390 * contains a control character, unprintable character, double quote mark,
1391 * or a space. Unescaped strings will start and end with a double quote mark.
1392 * Strings that are escaped are printed in hex (2 digits per char).
1393 *
1394 * The caller specifies the number of characters in the string to log, which may
1395 * or may not be the entire string.
1396 */
1397void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1398                                 size_t len)
1399{
1400        if (audit_string_contains_control(string, len))
1401                audit_log_n_hex(ab, string, len);
1402        else
1403                audit_log_n_string(ab, string, len);
1404}
1405
1406/**
1407 * audit_log_untrustedstring - log a string that may contain random characters
1408 * @ab: audit_buffer
1409 * @string: string to be logged
1410 *
1411 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1412 * determine string length.
1413 */
1414void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1415{
1416        audit_log_n_untrustedstring(ab, string, strlen(string));
1417}
1418
1419/* This is a helper-function to print the escaped d_path */
1420void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1421                      const struct path *path)
1422{
1423        char *p, *pathname;
1424
1425        if (prefix)
1426                audit_log_format(ab, "%s", prefix);
1427
1428        /* We will allow 11 spaces for ' (deleted)' to be appended */
1429        pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1430        if (!pathname) {
1431                audit_log_string(ab, "<no_memory>");
1432                return;
1433        }
1434        p = d_path(path, pathname, PATH_MAX+11);
1435        if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1436                /* FIXME: can we save some information here? */
1437                audit_log_string(ab, "<too_long>");
1438        } else
1439                audit_log_untrustedstring(ab, p);
1440        kfree(pathname);
1441}
1442
1443void audit_log_key(struct audit_buffer *ab, char *key)
1444{
1445        audit_log_format(ab, " key=");
1446        if (key)
1447                audit_log_untrustedstring(ab, key);
1448        else
1449                audit_log_format(ab, "(null)");
1450}
1451
1452/**
1453 * audit_log_end - end one audit record
1454 * @ab: the audit_buffer
1455 *
1456 * The netlink_* functions cannot be called inside an irq context, so
1457 * the audit buffer is placed on a queue and a tasklet is scheduled to
1458 * remove them from the queue outside the irq context.  May be called in
1459 * any context.
1460 */
1461void audit_log_end(struct audit_buffer *ab)
1462{
1463        if (!ab)
1464                return;
1465        if (!audit_rate_check()) {
1466                audit_log_lost("rate limit exceeded");
1467        } else {
1468                struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1469                nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1470
1471                if (audit_pid) {
1472                        skb_queue_tail(&audit_skb_queue, ab->skb);
1473                        wake_up_interruptible(&kauditd_wait);
1474                } else {
1475                        audit_printk_skb(ab->skb);
1476                }
1477                ab->skb = NULL;
1478        }
1479        audit_buffer_free(ab);
1480}
1481
1482/**
1483 * audit_log - Log an audit record
1484 * @ctx: audit context
1485 * @gfp_mask: type of allocation
1486 * @type: audit message type
1487 * @fmt: format string to use
1488 * @...: variable parameters matching the format string
1489 *
1490 * This is a convenience function that calls audit_log_start,
1491 * audit_log_vformat, and audit_log_end.  It may be called
1492 * in any context.
1493 */
1494void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1495               const char *fmt, ...)
1496{
1497        struct audit_buffer *ab;
1498        va_list args;
1499
1500        ab = audit_log_start(ctx, gfp_mask, type);
1501        if (ab) {
1502                va_start(args, fmt);
1503                audit_log_vformat(ab, fmt, args);
1504                va_end(args);
1505                audit_log_end(ab);
1506        }
1507}
1508
1509#ifdef CONFIG_SECURITY
1510/**
1511 * audit_log_secctx - Converts and logs SELinux context
1512 * @ab: audit_buffer
1513 * @secid: security number
1514 *
1515 * This is a helper function that calls security_secid_to_secctx to convert
1516 * secid to secctx and then adds the (converted) SELinux context to the audit
1517 * log by calling audit_log_format, thus also preventing leak of internal secid
1518 * to userspace. If secid cannot be converted audit_panic is called.
1519 */
1520void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1521{
1522        u32 len;
1523        char *secctx;
1524
1525        if (security_secid_to_secctx(secid, &secctx, &len)) {
1526                audit_panic("Cannot convert secid to context");
1527        } else {
1528                audit_log_format(ab, " obj=%s", secctx);
1529                security_release_secctx(secctx, len);
1530        }
1531}
1532EXPORT_SYMBOL(audit_log_secctx);
1533#endif
1534
1535EXPORT_SYMBOL(audit_log_start);
1536EXPORT_SYMBOL(audit_log_end);
1537EXPORT_SYMBOL(audit_log_format);
1538EXPORT_SYMBOL(audit_log);
1539
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