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_put(skb, pid, seq, t, size, flags);
 520        if (!nlh)
 521                goto out_kfree_skb;
 522        data = nlmsg_data(nlh);
 523        memcpy(data, payload, size);
 524        return skb;
 525
 526out_kfree_skb:
 527        kfree_skb(skb);
 528        return NULL;
 529}
 530
 531static int audit_send_reply_thread(void *arg)
 532{
 533        struct audit_reply *reply = (struct audit_reply *)arg;
 534
 535        mutex_lock(&audit_cmd_mutex);
 536        mutex_unlock(&audit_cmd_mutex);
 537
 538        /* Ignore failure. It'll only happen if the sender goes away,
 539           because our timeout is set to infinite. */
 540        netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
 541        kfree(reply);
 542        return 0;
 543}
 544/**
 545 * audit_send_reply - send an audit reply message via netlink
 546 * @pid: process id to send reply to
 547 * @seq: sequence number
 548 * @type: audit message type
 549 * @done: done (last) flag
 550 * @multi: multi-part message flag
 551 * @payload: payload data
 552 * @size: payload size
 553 *
 554 * Allocates an skb, builds the netlink message, and sends it to the pid.
 555 * No failure notifications.
 556 */
 557static void audit_send_reply(int pid, int seq, int type, int done, int multi,
 558                             const void *payload, int size)
 559{
 560        struct sk_buff *skb;
 561        struct task_struct *tsk;
 562        struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
 563                                            GFP_KERNEL);
 564
 565        if (!reply)
 566                return;
 567
 568        skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
 569        if (!skb)
 570                goto out;
 571
 572        reply->pid = pid;
 573        reply->skb = skb;
 574
 575        tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
 576        if (!IS_ERR(tsk))
 577                return;
 578        kfree_skb(skb);
 579out:
 580        kfree(reply);
 581}
 582
 583/*
 584 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 585 * control messages.
 586 */
 587static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 588{
 589        int err = 0;
 590
 591        switch (msg_type) {
 592        case AUDIT_GET:
 593        case AUDIT_LIST:
 594        case AUDIT_LIST_RULES:
 595        case AUDIT_SET:
 596        case AUDIT_ADD:
 597        case AUDIT_ADD_RULE:
 598        case AUDIT_DEL:
 599        case AUDIT_DEL_RULE:
 600        case AUDIT_SIGNAL_INFO:
 601        case AUDIT_TTY_GET:
 602        case AUDIT_TTY_SET:
 603        case AUDIT_TRIM:
 604        case AUDIT_MAKE_EQUIV:
 605                if (!capable(CAP_AUDIT_CONTROL))
 606                        err = -EPERM;
 607                break;
 608        case AUDIT_USER:
 609        case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 610        case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 611                if (!capable(CAP_AUDIT_WRITE))
 612                        err = -EPERM;
 613                break;
 614        default:  /* bad msg */
 615                err = -EINVAL;
 616        }
 617
 618        return err;
 619}
 620
 621static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
 622                                     u32 pid, u32 uid, uid_t auid, u32 ses,
 623                                     u32 sid)
 624{
 625        int rc = 0;
 626        char *ctx = NULL;
 627        u32 len;
 628
 629        if (!audit_enabled) {
 630                *ab = NULL;
 631                return rc;
 632        }
 633
 634        *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 635        audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
 636                         pid, uid, auid, ses);
 637        if (sid) {
 638                rc = security_secid_to_secctx(sid, &ctx, &len);
 639                if (rc)
 640                        audit_log_format(*ab, " ssid=%u", sid);
 641                else {
 642                        audit_log_format(*ab, " subj=%s", ctx);
 643                        security_release_secctx(ctx, len);
 644                }
 645        }
 646
 647        return rc;
 648}
 649
 650static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 651{
 652        u32                     uid, pid, seq, sid;
 653        void                    *data;
 654        struct audit_status     *status_get, status_set;
 655        int                     err;
 656        struct audit_buffer     *ab;
 657        u16                     msg_type = nlh->nlmsg_type;
 658        uid_t                   loginuid; /* loginuid of sender */
 659        u32                     sessionid;
 660        struct audit_sig_info   *sig_data;
 661        char                    *ctx = NULL;
 662        u32                     len;
 663
 664        err = audit_netlink_ok(skb, msg_type);
 665        if (err)
 666                return err;
 667
 668        /* As soon as there's any sign of userspace auditd,
 669         * start kauditd to talk to it */
 670        if (!kauditd_task)
 671                kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 672        if (IS_ERR(kauditd_task)) {
 673                err = PTR_ERR(kauditd_task);
 674                kauditd_task = NULL;
 675                return err;
 676        }
 677
 678        pid  = NETLINK_CREDS(skb)->pid;
 679        uid  = NETLINK_CREDS(skb)->uid;
 680        loginuid = audit_get_loginuid(current);
 681        sessionid = audit_get_sessionid(current);
 682        security_task_getsecid(current, &sid);
 683        seq  = nlh->nlmsg_seq;
 684        data = nlmsg_data(nlh);
 685
 686        switch (msg_type) {
 687        case AUDIT_GET:
 688                status_set.enabled       = audit_enabled;
 689                status_set.failure       = audit_failure;
 690                status_set.pid           = audit_pid;
 691                status_set.rate_limit    = audit_rate_limit;
 692                status_set.backlog_limit = audit_backlog_limit;
 693                status_set.lost          = atomic_read(&audit_lost);
 694                status_set.backlog       = skb_queue_len(&audit_skb_queue);
 695                audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
 696                                 &status_set, sizeof(status_set));
 697                break;
 698        case AUDIT_SET:
 699                if (nlh->nlmsg_len < sizeof(struct audit_status))
 700                        return -EINVAL;
 701                status_get   = (struct audit_status *)data;
 702                if (status_get->mask & AUDIT_STATUS_ENABLED) {
 703                        err = audit_set_enabled(status_get->enabled,
 704                                                loginuid, sessionid, sid);
 705                        if (err < 0)
 706                                return err;
 707                }
 708                if (status_get->mask & AUDIT_STATUS_FAILURE) {
 709                        err = audit_set_failure(status_get->failure,
 710                                                loginuid, sessionid, sid);
 711                        if (err < 0)
 712                                return err;
 713                }
 714                if (status_get->mask & AUDIT_STATUS_PID) {
 715                        int new_pid = status_get->pid;
 716
 717                        if (audit_enabled != AUDIT_OFF)
 718                                audit_log_config_change("audit_pid", new_pid,
 719                                                        audit_pid, loginuid,
 720                                                        sessionid, sid, 1);
 721
 722                        audit_pid = new_pid;
 723                        audit_nlk_pid = NETLINK_CB(skb).pid;
 724                }
 725                if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
 726                        err = audit_set_rate_limit(status_get->rate_limit,
 727                                                   loginuid, sessionid, sid);
 728                        if (err < 0)
 729                                return err;
 730                }
 731                if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
 732                        err = audit_set_backlog_limit(status_get->backlog_limit,
 733                                                      loginuid, sessionid, sid);
 734                break;
 735        case AUDIT_USER:
 736        case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 737        case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 738                if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 739                        return 0;
 740
 741                err = audit_filter_user(&NETLINK_CB(skb));
 742                if (err == 1) {
 743                        err = 0;
 744                        if (msg_type == AUDIT_USER_TTY) {
 745                                err = audit_prepare_user_tty(pid, loginuid,
 746                                                             sessionid);
 747                                if (err)
 748                                        break;
 749                        }
 750                        audit_log_common_recv_msg(&ab, msg_type, pid, uid,
 751                                                  loginuid, sessionid, sid);
 752
 753                        if (msg_type != AUDIT_USER_TTY)
 754                                audit_log_format(ab, " msg='%.1024s'",
 755                                                 (char *)data);
 756                        else {
 757                                int size;
 758
 759                                audit_log_format(ab, " msg=");
 760                                size = nlmsg_len(nlh);
 761                                if (size > 0 &&
 762                                    ((unsigned char *)data)[size - 1] == '\0')
 763                                        size--;
 764                                audit_log_n_untrustedstring(ab, data, size);
 765                        }
 766                        audit_set_pid(ab, pid);
 767                        audit_log_end(ab);
 768                }
 769                break;
 770        case AUDIT_ADD:
 771        case AUDIT_DEL:
 772                if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 773                        return -EINVAL;
 774                if (audit_enabled == AUDIT_LOCKED) {
 775                        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 776                                                  uid, loginuid, sessionid, sid);
 777
 778                        audit_log_format(ab, " audit_enabled=%d res=0",
 779                                         audit_enabled);
 780                        audit_log_end(ab);
 781                        return -EPERM;
 782                }
 783                /* fallthrough */
 784        case AUDIT_LIST:
 785                err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
 786                                           uid, seq, data, nlmsg_len(nlh),
 787                                           loginuid, sessionid, sid);
 788                break;
 789        case AUDIT_ADD_RULE:
 790        case AUDIT_DEL_RULE:
 791                if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 792                        return -EINVAL;
 793                if (audit_enabled == AUDIT_LOCKED) {
 794                        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 795                                                  uid, loginuid, sessionid, sid);
 796
 797                        audit_log_format(ab, " audit_enabled=%d res=0",
 798                                         audit_enabled);
 799                        audit_log_end(ab);
 800                        return -EPERM;
 801                }
 802                /* fallthrough */
 803        case AUDIT_LIST_RULES:
 804                err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
 805                                           uid, seq, data, nlmsg_len(nlh),
 806                                           loginuid, sessionid, sid);
 807                break;
 808        case AUDIT_TRIM:
 809                audit_trim_trees();
 810
 811                audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 812                                          uid, loginuid, sessionid, sid);
 813
 814                audit_log_format(ab, " op=trim res=1");
 815                audit_log_end(ab);
 816                break;
 817        case AUDIT_MAKE_EQUIV: {
 818                void *bufp = data;
 819                u32 sizes[2];
 820                size_t msglen = nlmsg_len(nlh);
 821                char *old, *new;
 822
 823                err = -EINVAL;
 824                if (msglen < 2 * sizeof(u32))
 825                        break;
 826                memcpy(sizes, bufp, 2 * sizeof(u32));
 827                bufp += 2 * sizeof(u32);
 828                msglen -= 2 * sizeof(u32);
 829                old = audit_unpack_string(&bufp, &msglen, sizes[0]);
 830                if (IS_ERR(old)) {
 831                        err = PTR_ERR(old);
 832                        break;
 833                }
 834                new = audit_unpack_string(&bufp, &msglen, sizes[1]);
 835                if (IS_ERR(new)) {
 836                        err = PTR_ERR(new);
 837                        kfree(old);
 838                        break;
 839                }
 840                /* OK, here comes... */
 841                err = audit_tag_tree(old, new);
 842
 843                audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
 844                                          uid, loginuid, sessionid, sid);
 845
 846                audit_log_format(ab, " op=make_equiv old=");
 847                audit_log_untrustedstring(ab, old);
 848                audit_log_format(ab, " new=");
 849                audit_log_untrustedstring(ab, new);
 850                audit_log_format(ab, " res=%d", !err);
 851                audit_log_end(ab);
 852                kfree(old);
 853                kfree(new);
 854                break;
 855        }
 856        case AUDIT_SIGNAL_INFO:
 857                len = 0;
 858                if (audit_sig_sid) {
 859                        err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
 860                        if (err)
 861                                return err;
 862                }
 863                sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 864                if (!sig_data) {
 865                        if (audit_sig_sid)
 866                                security_release_secctx(ctx, len);
 867                        return -ENOMEM;
 868                }
 869                sig_data->uid = audit_sig_uid;
 870                sig_data->pid = audit_sig_pid;
 871                if (audit_sig_sid) {
 872                        memcpy(sig_data->ctx, ctx, len);
 873                        security_release_secctx(ctx, len);
 874                }
 875                audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
 876                                0, 0, sig_data, sizeof(*sig_data) + len);
 877                kfree(sig_data);
 878                break;
 879        case AUDIT_TTY_GET: {
 880                struct audit_tty_status s;
 881                struct task_struct *tsk;
 882                unsigned long flags;
 883
 884                rcu_read_lock();
 885                tsk = find_task_by_vpid(pid);
 886                if (tsk && lock_task_sighand(tsk, &flags)) {
 887                        s.enabled = tsk->signal->audit_tty != 0;
 888                        unlock_task_sighand(tsk, &flags);
 889                } else
 890                        err = -ESRCH;
 891                rcu_read_unlock();
 892
 893                if (!err)
 894                        audit_send_reply(NETLINK_CB(skb).pid, seq,
 895                                         AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
 896                break;
 897        }
 898        case AUDIT_TTY_SET: {
 899                struct audit_tty_status *s;
 900                struct task_struct *tsk;
 901                unsigned long flags;
 902
 903                if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
 904                        return -EINVAL;
 905                s = data;
 906                if (s->enabled != 0 && s->enabled != 1)
 907                        return -EINVAL;
 908                rcu_read_lock();
 909                tsk = find_task_by_vpid(pid);
 910                if (tsk && lock_task_sighand(tsk, &flags)) {
 911                        tsk->signal->audit_tty = s->enabled != 0;
 912                        unlock_task_sighand(tsk, &flags);
 913                } else
 914                        err = -ESRCH;
 915                rcu_read_unlock();
 916                break;
 917        }
 918        default:
 919                err = -EINVAL;
 920                break;
 921        }
 922
 923        return err < 0 ? err : 0;
 924}
 925
 926/*
 927 * Get message from skb.  Each message is processed by audit_receive_msg.
 928 * Malformed skbs with wrong length are discarded silently.
 929 */
 930static void audit_receive_skb(struct sk_buff *skb)
 931{
 932        struct nlmsghdr *nlh;
 933        /*
 934         * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
 935         * if the nlmsg_len was not aligned
 936         */
 937        int len;
 938        int err;
 939
 940        nlh = nlmsg_hdr(skb);
 941        len = skb->len;
 942
 943        while (NLMSG_OK(nlh, len)) {
 944                err = audit_receive_msg(skb, nlh);
 945                /* if err or if this message says it wants a response */
 946                if (err || (nlh->nlmsg_flags & NLM_F_ACK))
 947                        netlink_ack(skb, nlh, err);
 948
 949                nlh = NLMSG_NEXT(nlh, len);
 950        }
 951}
 952
 953/* Receive messages from netlink socket. */
 954static void audit_receive(struct sk_buff  *skb)
 955{
 956        mutex_lock(&audit_cmd_mutex);
 957        audit_receive_skb(skb);
 958        mutex_unlock(&audit_cmd_mutex);
 959}
 960
 961/* Initialize audit support at boot time. */
 962static int __init audit_init(void)
 963{
 964        int i;
 965        struct netlink_kernel_cfg cfg = {
 966                .input  = audit_receive,
 967        };
 968
 969        if (audit_initialized == AUDIT_DISABLED)
 970                return 0;
 971
 972        printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
 973               audit_default ? "enabled" : "disabled");
 974        audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT,
 975                                           THIS_MODULE, &cfg);
 976        if (!audit_sock)
 977                audit_panic("cannot initialize netlink socket");
 978        else
 979                audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
 980
 981        skb_queue_head_init(&audit_skb_queue);
 982        skb_queue_head_init(&audit_skb_hold_queue);
 983        audit_initialized = AUDIT_INITIALIZED;
 984        audit_enabled = audit_default;
 985        audit_ever_enabled |= !!audit_default;
 986
 987        audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
 988
 989        for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
 990                INIT_LIST_HEAD(&audit_inode_hash[i]);
 991
 992        return 0;
 993}
 994__initcall(audit_init);
 995
 996/* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
 997static int __init audit_enable(char *str)
 998{
 999        audit_default = !!simple_strtol(str, NULL, 0);
1000        if (!audit_default)
1001                audit_initialized = AUDIT_DISABLED;
1002
1003        printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
1004
1005        if (audit_initialized == AUDIT_INITIALIZED) {
1006                audit_enabled = audit_default;
1007                audit_ever_enabled |= !!audit_default;
1008        } else if (audit_initialized == AUDIT_UNINITIALIZED) {
1009                printk(" (after initialization)");
1010        } else {
1011                printk(" (until reboot)");
1012        }
1013        printk("\n");
1014
1015        return 1;
1016}
1017
1018__setup("audit=", audit_enable);
1019
1020static void audit_buffer_free(struct audit_buffer *ab)
1021{
1022        unsigned long flags;
1023
1024        if (!ab)
1025                return;
1026
1027        if (ab->skb)
1028                kfree_skb(ab->skb);
1029
1030        spin_lock_irqsave(&audit_freelist_lock, flags);
1031        if (audit_freelist_count > AUDIT_MAXFREE)
1032                kfree(ab);
1033        else {
1034                audit_freelist_count++;
1035                list_add(&ab->list, &audit_freelist);
1036        }
1037        spin_unlock_irqrestore(&audit_freelist_lock, flags);
1038}
1039
1040static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1041                                                gfp_t gfp_mask, int type)
1042{
1043        unsigned long flags;
1044        struct audit_buffer *ab = NULL;
1045        struct nlmsghdr *nlh;
1046
1047        spin_lock_irqsave(&audit_freelist_lock, flags);
1048        if (!list_empty(&audit_freelist)) {
1049                ab = list_entry(audit_freelist.next,
1050                                struct audit_buffer, list);
1051                list_del(&ab->list);
1052                --audit_freelist_count;
1053        }
1054        spin_unlock_irqrestore(&audit_freelist_lock, flags);
1055
1056        if (!ab) {
1057                ab = kmalloc(sizeof(*ab), gfp_mask);
1058                if (!ab)
1059                        goto err;
1060        }
1061
1062        ab->ctx = ctx;
1063        ab->gfp_mask = gfp_mask;
1064
1065        ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1066        if (!ab->skb)
1067                goto err;
1068
1069        nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1070        if (!nlh)
1071                goto out_kfree_skb;
1072
1073        return ab;
1074
1075out_kfree_skb:
1076        kfree_skb(ab->skb);
1077        ab->skb = NULL;
1078err:
1079        audit_buffer_free(ab);
1080        return NULL;
1081}
1082
1083/**
1084 * audit_serial - compute a serial number for the audit record
1085 *
1086 * Compute a serial number for the audit record.  Audit records are
1087 * written to user-space as soon as they are generated, so a complete
1088 * audit record may be written in several pieces.  The timestamp of the
1089 * record and this serial number are used by the user-space tools to
1090 * determine which pieces belong to the same audit record.  The
1091 * (timestamp,serial) tuple is unique for each syscall and is live from
1092 * syscall entry to syscall exit.
1093 *
1094 * NOTE: Another possibility is to store the formatted records off the
1095 * audit context (for those records that have a context), and emit them
1096 * all at syscall exit.  However, this could delay the reporting of
1097 * significant errors until syscall exit (or never, if the system
1098 * halts).
1099 */
1100unsigned int audit_serial(void)
1101{
1102        static DEFINE_SPINLOCK(serial_lock);
1103        static unsigned int serial = 0;
1104
1105        unsigned long flags;
1106        unsigned int ret;
1107
1108        spin_lock_irqsave(&serial_lock, flags);
1109        do {
1110                ret = ++serial;
1111        } while (unlikely(!ret));
1112        spin_unlock_irqrestore(&serial_lock, flags);
1113
1114        return ret;
1115}
1116
1117static inline void audit_get_stamp(struct audit_context *ctx,
1118                                   struct timespec *t, unsigned int *serial)
1119{
1120        if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1121                *t = CURRENT_TIME;
1122                *serial = audit_serial();
1123        }
1124}
1125
1126/* Obtain an audit buffer.  This routine does locking to obtain the
1127 * audit buffer, but then no locking is required for calls to
1128 * audit_log_*format.  If the tsk is a task that is currently in a
1129 * syscall, then the syscall is marked as auditable and an audit record
1130 * will be written at syscall exit.  If there is no associated task, tsk
1131 * should be NULL. */
1132
1133/**
1134 * audit_log_start - obtain an audit buffer
1135 * @ctx: audit_context (may be NULL)
1136 * @gfp_mask: type of allocation
1137 * @type: audit message type
1138 *
1139 * Returns audit_buffer pointer on success or NULL on error.
1140 *
1141 * Obtain an audit buffer.  This routine does locking to obtain the
1142 * audit buffer, but then no locking is required for calls to
1143 * audit_log_*format.  If the task (ctx) is a task that is currently in a
1144 * syscall, then the syscall is marked as auditable and an audit record
1145 * will be written at syscall exit.  If there is no associated task, then
1146 * task context (ctx) should be NULL.
1147 */
1148struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1149                                     int type)
1150{
1151        struct audit_buffer     *ab     = NULL;
1152        struct timespec         t;
1153        unsigned int            uninitialized_var(serial);
1154        int reserve;
1155        unsigned long timeout_start = jiffies;
1156
1157        if (audit_initialized != AUDIT_INITIALIZED)
1158                return NULL;
1159
1160        if (unlikely(audit_filter_type(type)))
1161                return NULL;
1162
1163        if (gfp_mask & __GFP_WAIT)
1164                reserve = 0;
1165        else
1166                reserve = 5; /* Allow atomic callers to go up to five
1167                                entries over the normal backlog limit */
1168
1169        while (audit_backlog_limit
1170               && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1171                if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1172                    && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1173
1174                        /* Wait for auditd to drain the queue a little */
1175                        DECLARE_WAITQUEUE(wait, current);
1176                        set_current_state(TASK_INTERRUPTIBLE);
1177                        add_wait_queue(&audit_backlog_wait, &wait);
1178
1179                        if (audit_backlog_limit &&
1180                            skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1181                                schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1182
1183                        __set_current_state(TASK_RUNNING);
1184                        remove_wait_queue(&audit_backlog_wait, &wait);
1185                        continue;
1186                }
1187                if (audit_rate_check() && printk_ratelimit())
1188                        printk(KERN_WARNING
1189                               "audit: audit_backlog=%d > "
1190                               "audit_backlog_limit=%d\n",
1191                               skb_queue_len(&audit_skb_queue),
1192                               audit_backlog_limit);
1193                audit_log_lost("backlog limit exceeded");
1194                audit_backlog_wait_time = audit_backlog_wait_overflow;
1195                wake_up(&audit_backlog_wait);
1196                return NULL;
1197        }
1198
1199        ab = audit_buffer_alloc(ctx, gfp_mask, type);
1200        if (!ab) {
1201                audit_log_lost("out of memory in audit_log_start");
1202                return NULL;
1203        }
1204
1205        audit_get_stamp(ab->ctx, &t, &serial);
1206
1207        audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1208                         t.tv_sec, t.tv_nsec/1000000, serial);
1209        return ab;
1210}
1211
1212/**
1213 * audit_expand - expand skb in the audit buffer
1214 * @ab: audit_buffer
1215 * @extra: space to add at tail of the skb
1216 *
1217 * Returns 0 (no space) on failed expansion, or available space if
1218 * successful.
1219 */
1220static inline int audit_expand(struct audit_buffer *ab, int extra)
1221{
1222        struct sk_buff *skb = ab->skb;
1223        int oldtail = skb_tailroom(skb);
1224        int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1225        int newtail = skb_tailroom(skb);
1226
1227        if (ret < 0) {
1228                audit_log_lost("out of memory in audit_expand");
1229                return 0;
1230        }
1231
1232        skb->truesize += newtail - oldtail;
1233        return newtail;
1234}
1235
1236/*
1237 * Format an audit message into the audit buffer.  If there isn't enough
1238 * room in the audit buffer, more room will be allocated and vsnprint
1239 * will be called a second time.  Currently, we assume that a printk
1240 * can't format message larger than 1024 bytes, so we don't either.
1241 */
1242static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1243                              va_list args)
1244{
1245        int len, avail;
1246        struct sk_buff *skb;
1247        va_list args2;
1248
1249        if (!ab)
1250                return;
1251
1252        BUG_ON(!ab->skb);
1253        skb = ab->skb;
1254        avail = skb_tailroom(skb);
1255        if (avail == 0) {
1256                avail = audit_expand(ab, AUDIT_BUFSIZ);
1257                if (!avail)
1258                        goto out;
1259        }
1260        va_copy(args2, args);
1261        len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1262        if (len >= avail) {
1263                /* The printk buffer is 1024 bytes long, so if we get
1264                 * here and AUDIT_BUFSIZ is at least 1024, then we can
1265                 * log everything that printk could have logged. */
1266                avail = audit_expand(ab,
1267                        max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1268                if (!avail)
1269                        goto out_va_end;
1270                len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1271        }
1272        if (len > 0)
1273                skb_put(skb, len);
1274out_va_end:
1275        va_end(args2);
1276out:
1277        return;
1278}
1279
1280/**
1281 * audit_log_format - format a message into the audit buffer.
1282 * @ab: audit_buffer
1283 * @fmt: format string
1284 * @...: optional parameters matching @fmt string
1285 *
1286 * All the work is done in audit_log_vformat.
1287 */
1288void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1289{
1290        va_list args;
1291
1292        if (!ab)
1293                return;
1294        va_start(args, fmt);
1295        audit_log_vformat(ab, fmt, args);
1296        va_end(args);
1297}
1298
1299/**
1300 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1301 * @ab: the audit_buffer
1302 * @buf: buffer to convert to hex
1303 * @len: length of @buf to be converted
1304 *
1305 * No return value; failure to expand is silently ignored.
1306 *
1307 * This function will take the passed buf and convert it into a string of
1308 * ascii hex digits. The new string is placed onto the skb.
1309 */
1310void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1311                size_t len)
1312{
1313        int i, avail, new_len;
1314        unsigned char *ptr;
1315        struct sk_buff *skb;
1316        static const unsigned char *hex = "0123456789ABCDEF";
1317
1318        if (!ab)
1319                return;
1320
1321        BUG_ON(!ab->skb);
1322        skb = ab->skb;
1323        avail = skb_tailroom(skb);
1324        new_len = len<<1;
1325        if (new_len >= avail) {
1326                /* Round the buffer request up to the next multiple */
1327                new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1328                avail = audit_expand(ab, new_len);
1329                if (!avail)
1330                        return;
1331        }
1332
1333        ptr = skb_tail_pointer(skb);
1334        for (i=0; i<len; i++) {
1335                *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1336                *ptr++ = hex[buf[i] & 0x0F];      /* Lower nibble */
1337        }
1338        *ptr = 0;
1339        skb_put(skb, len << 1); /* new string is twice the old string */
1340}
1341
1342/*
1343 * Format a string of no more than slen characters into the audit buffer,
1344 * enclosed in quote marks.
1345 */
1346void audit_log_n_string(struct audit_buffer *ab, const char *string,
1347                        size_t slen)
1348{
1349        int avail, new_len;
1350        unsigned char *ptr;
1351        struct sk_buff *skb;
1352
1353        if (!ab)
1354                return;
1355
1356        BUG_ON(!ab->skb);
1357        skb = ab->skb;
1358        avail = skb_tailroom(skb);
1359        new_len = slen + 3;     /* enclosing quotes + null terminator */
1360        if (new_len > avail) {
1361                avail = audit_expand(ab, new_len);
1362                if (!avail)
1363                        return;
1364        }
1365        ptr = skb_tail_pointer(skb);
1366        *ptr++ = '"';
1367        memcpy(ptr, string, slen);
1368        ptr += slen;
1369        *ptr++ = '"';
1370        *ptr = 0;
1371        skb_put(skb, slen + 2); /* don't include null terminator */
1372}
1373
1374/**
1375 * audit_string_contains_control - does a string need to be logged in hex
1376 * @string: string to be checked
1377 * @len: max length of the string to check
1378 */
1379int audit_string_contains_control(const char *string, size_t len)
1380{
1381        const unsigned char *p;
1382        for (p = string; p < (const unsigned char *)string + len; p++) {
1383                if (*p == '"' || *p < 0x21 || *p > 0x7e)
1384                        return 1;
1385        }
1386        return 0;
1387}
1388
1389/**
1390 * audit_log_n_untrustedstring - log a string that may contain random characters
1391 * @ab: audit_buffer
1392 * @len: length of string (not including trailing null)
1393 * @string: string to be logged
1394 *
1395 * This code will escape a string that is passed to it if the string
1396 * contains a control character, unprintable character, double quote mark,
1397 * or a space. Unescaped strings will start and end with a double quote mark.
1398 * Strings that are escaped are printed in hex (2 digits per char).
1399 *
1400 * The caller specifies the number of characters in the string to log, which may
1401 * or may not be the entire string.
1402 */
1403void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1404                                 size_t len)
1405{
1406        if (audit_string_contains_control(string, len))
1407                audit_log_n_hex(ab, string, len);
1408        else
1409                audit_log_n_string(ab, string, len);
1410}
1411
1412/**
1413 * audit_log_untrustedstring - log a string that may contain random characters
1414 * @ab: audit_buffer
1415 * @string: string to be logged
1416 *
1417 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1418 * determine string length.
1419 */
1420void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1421{
1422        audit_log_n_untrustedstring(ab, string, strlen(string));
1423}
1424
1425/* This is a helper-function to print the escaped d_path */
1426void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1427                      const struct path *path)
1428{
1429        char *p, *pathname;
1430
1431        if (prefix)
1432                audit_log_format(ab, "%s", prefix);
1433
1434        /* We will allow 11 spaces for ' (deleted)' to be appended */
1435        pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1436        if (!pathname) {
1437                audit_log_string(ab, "<no_memory>");
1438                return;
1439        }
1440        p = d_path(path, pathname, PATH_MAX+11);
1441        if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1442                /* FIXME: can we save some information here? */
1443                audit_log_string(ab, "<too_long>");
1444        } else
1445                audit_log_untrustedstring(ab, p);
1446        kfree(pathname);
1447}
1448
1449void audit_log_key(struct audit_buffer *ab, char *key)
1450{
1451        audit_log_format(ab, " key=");
1452        if (key)
1453                audit_log_untrustedstring(ab, key);
1454        else
1455                audit_log_format(ab, "(null)");
1456}
1457
1458/**
1459 * audit_log_link_denied - report a link restriction denial
1460 * @operation: specific link opreation
1461 * @link: the path that triggered the restriction
1462 */
1463void audit_log_link_denied(const char *operation, struct path *link)
1464{
1465        struct audit_buffer *ab;
1466
1467        ab = audit_log_start(current->audit_context, GFP_KERNEL,
1468                             AUDIT_ANOM_LINK);
1469        if (!ab)
1470                return;
1471        audit_log_format(ab, "op=%s action=denied", operation);
1472        audit_log_format(ab, " pid=%d comm=", current->pid);
1473        audit_log_untrustedstring(ab, current->comm);
1474        audit_log_d_path(ab, " path=", link);
1475        audit_log_format(ab, " dev=");
1476        audit_log_untrustedstring(ab, link->dentry->d_inode->i_sb->s_id);
1477        audit_log_format(ab, " ino=%lu", link->dentry->d_inode->i_ino);
1478        audit_log_end(ab);
1479}
1480
1481/**
1482 * audit_log_end - end one audit record
1483 * @ab: the audit_buffer
1484 *
1485 * The netlink_* functions cannot be called inside an irq context, so
1486 * the audit buffer is placed on a queue and a tasklet is scheduled to
1487 * remove them from the queue outside the irq context.  May be called in
1488 * any context.
1489 */
1490void audit_log_end(struct audit_buffer *ab)
1491{
1492        if (!ab)
1493                return;
1494        if (!audit_rate_check()) {
1495                audit_log_lost("rate limit exceeded");
1496        } else {
1497                struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1498                nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1499
1500                if (audit_pid) {
1501                        skb_queue_tail(&audit_skb_queue, ab->skb);
1502                        wake_up_interruptible(&kauditd_wait);
1503                } else {
1504                        audit_printk_skb(ab->skb);
1505                }
1506                ab->skb = NULL;
1507        }
1508        audit_buffer_free(ab);
1509}
1510
1511/**
1512 * audit_log - Log an audit record
1513 * @ctx: audit context
1514 * @gfp_mask: type of allocation
1515 * @type: audit message type
1516 * @fmt: format string to use
1517 * @...: variable parameters matching the format string
1518 *
1519 * This is a convenience function that calls audit_log_start,
1520 * audit_log_vformat, and audit_log_end.  It may be called
1521 * in any context.
1522 */
1523void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1524               const char *fmt, ...)
1525{
1526        struct audit_buffer *ab;
1527        va_list args;
1528
1529        ab = audit_log_start(ctx, gfp_mask, type);
1530        if (ab) {
1531                va_start(args, fmt);
1532                audit_log_vformat(ab, fmt, args);
1533                va_end(args);
1534                audit_log_end(ab);
1535        }
1536}
1537
1538#ifdef CONFIG_SECURITY
1539/**
1540 * audit_log_secctx - Converts and logs SELinux context
1541 * @ab: audit_buffer
1542 * @secid: security number
1543 *
1544 * This is a helper function that calls security_secid_to_secctx to convert
1545 * secid to secctx and then adds the (converted) SELinux context to the audit
1546 * log by calling audit_log_format, thus also preventing leak of internal secid
1547 * to userspace. If secid cannot be converted audit_panic is called.
1548 */
1549void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1550{
1551        u32 len;
1552        char *secctx;
1553
1554        if (security_secid_to_secctx(secid, &secctx, &len)) {
1555                audit_panic("Cannot convert secid to context");
1556        } else {
1557                audit_log_format(ab, " obj=%s", secctx);
1558                security_release_secctx(secctx, len);
1559        }
1560}
1561EXPORT_SYMBOL(audit_log_secctx);
1562#endif
1563
1564EXPORT_SYMBOL(audit_log_start);
1565EXPORT_SYMBOL(audit_log_end);
1566EXPORT_SYMBOL(audit_log_format);
1567EXPORT_SYMBOL(audit_log);
1568
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