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#include <linux/pid_namespace.h>
  65
  66#include "audit.h"
  67
  68/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
  69 * (Initialization happens after skb_init is called.) */
  70#define AUDIT_DISABLED          -1
  71#define AUDIT_UNINITIALIZED     0
  72#define AUDIT_INITIALIZED       1
  73static int      audit_initialized;
  74
  75#define AUDIT_OFF       0
  76#define AUDIT_ON        1
  77#define AUDIT_LOCKED    2
  78int             audit_enabled;
  79int             audit_ever_enabled;
  80
  81EXPORT_SYMBOL_GPL(audit_enabled);
  82
  83/* Default state when kernel boots without any parameters. */
  84static int      audit_default;
  85
  86/* If auditing cannot proceed, audit_failure selects what happens. */
  87static int      audit_failure = AUDIT_FAIL_PRINTK;
  88
  89/*
  90 * If audit records are to be written to the netlink socket, audit_pid
  91 * contains the pid of the auditd process and audit_nlk_portid contains
  92 * the portid to use to send netlink messages to that process.
  93 */
  94int             audit_pid;
  95static int      audit_nlk_portid;
  96
  97/* If audit_rate_limit is non-zero, limit the rate of sending audit records
  98 * to that number per second.  This prevents DoS attacks, but results in
  99 * audit records being dropped. */
 100static int      audit_rate_limit;
 101
 102/* Number of outstanding audit_buffers allowed. */
 103static int      audit_backlog_limit = 64;
 104static int      audit_backlog_wait_time = 60 * HZ;
 105static int      audit_backlog_wait_overflow = 0;
 106
 107/* The identity of the user shutting down the audit system. */
 108kuid_t          audit_sig_uid = INVALID_UID;
 109pid_t           audit_sig_pid = -1;
 110u32             audit_sig_sid = 0;
 111
 112/* Records can be lost in several ways:
 113   0) [suppressed in audit_alloc]
 114   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
 115   2) out of memory in audit_log_move [alloc_skb]
 116   3) suppressed due to audit_rate_limit
 117   4) suppressed due to audit_backlog_limit
 118*/
 119static atomic_t    audit_lost = ATOMIC_INIT(0);
 120
 121/* The netlink socket. */
 122static struct sock *audit_sock;
 123
 124/* Hash for inode-based rules */
 125struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 126
 127/* The audit_freelist is a list of pre-allocated audit buffers (if more
 128 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
 129 * being placed on the freelist). */
 130static DEFINE_SPINLOCK(audit_freelist_lock);
 131static int         audit_freelist_count;
 132static LIST_HEAD(audit_freelist);
 133
 134static struct sk_buff_head audit_skb_queue;
 135/* queue of skbs to send to auditd when/if it comes back */
 136static struct sk_buff_head audit_skb_hold_queue;
 137static struct task_struct *kauditd_task;
 138static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 139static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 140
 141/* Serialize requests from userspace. */
 142DEFINE_MUTEX(audit_cmd_mutex);
 143
 144/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 145 * audit records.  Since printk uses a 1024 byte buffer, this buffer
 146 * should be at least that large. */
 147#define AUDIT_BUFSIZ 1024
 148
 149/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
 150 * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
 151#define AUDIT_MAXFREE  (2*NR_CPUS)
 152
 153/* The audit_buffer is used when formatting an audit record.  The caller
 154 * locks briefly to get the record off the freelist or to allocate the
 155 * buffer, and locks briefly to send the buffer to the netlink layer or
 156 * to place it on a transmit queue.  Multiple audit_buffers can be in
 157 * use simultaneously. */
 158struct audit_buffer {
 159        struct list_head     list;
 160        struct sk_buff       *skb;      /* formatted skb ready to send */
 161        struct audit_context *ctx;      /* NULL or associated context */
 162        gfp_t                gfp_mask;
 163};
 164
 165struct audit_reply {
 166        int pid;
 167        struct sk_buff *skb;
 168};
 169
 170static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
 171{
 172        if (ab) {
 173                struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
 174                nlh->nlmsg_pid = pid;
 175        }
 176}
 177
 178void audit_panic(const char *message)
 179{
 180        switch (audit_failure)
 181        {
 182        case AUDIT_FAIL_SILENT:
 183                break;
 184        case AUDIT_FAIL_PRINTK:
 185                if (printk_ratelimit())
 186                        printk(KERN_ERR "audit: %s\n", message);
 187                break;
 188        case AUDIT_FAIL_PANIC:
 189                /* test audit_pid since printk is always losey, why bother? */
 190                if (audit_pid)
 191                        panic("audit: %s\n", message);
 192                break;
 193        }
 194}
 195
 196static inline int audit_rate_check(void)
 197{
 198        static unsigned long    last_check = 0;
 199        static int              messages   = 0;
 200        static DEFINE_SPINLOCK(lock);
 201        unsigned long           flags;
 202        unsigned long           now;
 203        unsigned long           elapsed;
 204        int                     retval     = 0;
 205
 206        if (!audit_rate_limit) return 1;
 207
 208        spin_lock_irqsave(&lock, flags);
 209        if (++messages < audit_rate_limit) {
 210                retval = 1;
 211        } else {
 212                now     = jiffies;
 213                elapsed = now - last_check;
 214                if (elapsed > HZ) {
 215                        last_check = now;
 216                        messages   = 0;
 217                        retval     = 1;
 218                }
 219        }
 220        spin_unlock_irqrestore(&lock, flags);
 221
 222        return retval;
 223}
 224
 225/**
 226 * audit_log_lost - conditionally log lost audit message event
 227 * @message: the message stating reason for lost audit message
 228 *
 229 * Emit at least 1 message per second, even if audit_rate_check is
 230 * throttling.
 231 * Always increment the lost messages counter.
 232*/
 233void audit_log_lost(const char *message)
 234{
 235        static unsigned long    last_msg = 0;
 236        static DEFINE_SPINLOCK(lock);
 237        unsigned long           flags;
 238        unsigned long           now;
 239        int                     print;
 240
 241        atomic_inc(&audit_lost);
 242
 243        print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 244
 245        if (!print) {
 246                spin_lock_irqsave(&lock, flags);
 247                now = jiffies;
 248                if (now - last_msg > HZ) {
 249                        print = 1;
 250                        last_msg = now;
 251                }
 252                spin_unlock_irqrestore(&lock, flags);
 253        }
 254
 255        if (print) {
 256                if (printk_ratelimit())
 257                        printk(KERN_WARNING
 258                                "audit: audit_lost=%d audit_rate_limit=%d "
 259                                "audit_backlog_limit=%d\n",
 260                                atomic_read(&audit_lost),
 261                                audit_rate_limit,
 262                                audit_backlog_limit);
 263                audit_panic(message);
 264        }
 265}
 266
 267static int audit_log_config_change(char *function_name, int new, int old,
 268                                   kuid_t loginuid, u32 sessionid, u32 sid,
 269                                   int allow_changes)
 270{
 271        struct audit_buffer *ab;
 272        int rc = 0;
 273
 274        ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 275        if (unlikely(!ab))
 276                return rc;
 277        audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
 278                         old, from_kuid(&init_user_ns, loginuid), sessionid);
 279        if (sid) {
 280                char *ctx = NULL;
 281                u32 len;
 282
 283                rc = security_secid_to_secctx(sid, &ctx, &len);
 284                if (rc) {
 285                        audit_log_format(ab, " sid=%u", sid);
 286                        allow_changes = 0; /* Something weird, deny request */
 287                } else {
 288                        audit_log_format(ab, " subj=%s", ctx);
 289                        security_release_secctx(ctx, len);
 290                }
 291        }
 292        audit_log_format(ab, " res=%d", allow_changes);
 293        audit_log_end(ab);
 294        return rc;
 295}
 296
 297static int audit_do_config_change(char *function_name, int *to_change,
 298                                  int new, kuid_t loginuid, u32 sessionid,
 299                                  u32 sid)
 300{
 301        int allow_changes, rc = 0, old = *to_change;
 302
 303        /* check if we are locked */
 304        if (audit_enabled == AUDIT_LOCKED)
 305                allow_changes = 0;
 306        else
 307                allow_changes = 1;
 308
 309        if (audit_enabled != AUDIT_OFF) {
 310                rc = audit_log_config_change(function_name, new, old, loginuid,
 311                                             sessionid, sid, allow_changes);
 312                if (rc)
 313                        allow_changes = 0;
 314        }
 315
 316        /* If we are allowed, make the change */
 317        if (allow_changes == 1)
 318                *to_change = new;
 319        /* Not allowed, update reason */
 320        else if (rc == 0)
 321                rc = -EPERM;
 322        return rc;
 323}
 324
 325static int audit_set_rate_limit(int limit, kuid_t loginuid, u32 sessionid,
 326                                u32 sid)
 327{
 328        return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
 329                                      limit, loginuid, sessionid, sid);
 330}
 331
 332static int audit_set_backlog_limit(int limit, kuid_t loginuid, u32 sessionid,
 333                                   u32 sid)
 334{
 335        return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
 336                                      limit, loginuid, sessionid, sid);
 337}
 338
 339static int audit_set_enabled(int state, kuid_t loginuid, u32 sessionid, u32 sid)
 340{
 341        int rc;
 342        if (state < AUDIT_OFF || state > AUDIT_LOCKED)
 343                return -EINVAL;
 344
 345        rc =  audit_do_config_change("audit_enabled", &audit_enabled, state,
 346                                     loginuid, sessionid, sid);
 347
 348        if (!rc)
 349                audit_ever_enabled |= !!state;
 350
 351        return rc;
 352}
 353
 354static int audit_set_failure(int state, kuid_t loginuid, u32 sessionid, u32 sid)
 355{
 356        if (state != AUDIT_FAIL_SILENT
 357            && state != AUDIT_FAIL_PRINTK
 358            && state != AUDIT_FAIL_PANIC)
 359                return -EINVAL;
 360
 361        return audit_do_config_change("audit_failure", &audit_failure, state,
 362                                      loginuid, sessionid, sid);
 363}
 364
 365/*
 366 * Queue skbs to be sent to auditd when/if it comes back.  These skbs should
 367 * already have been sent via prink/syslog and so if these messages are dropped
 368 * it is not a huge concern since we already passed the audit_log_lost()
 369 * notification and stuff.  This is just nice to get audit messages during
 370 * boot before auditd is running or messages generated while auditd is stopped.
 371 * This only holds messages is audit_default is set, aka booting with audit=1
 372 * or building your kernel that way.
 373 */
 374static void audit_hold_skb(struct sk_buff *skb)
 375{
 376        if (audit_default &&
 377            skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
 378                skb_queue_tail(&audit_skb_hold_queue, skb);
 379        else
 380                kfree_skb(skb);
 381}
 382
 383/*
 384 * For one reason or another this nlh isn't getting delivered to the userspace
 385 * audit daemon, just send it to printk.
 386 */
 387static void audit_printk_skb(struct sk_buff *skb)
 388{
 389        struct nlmsghdr *nlh = nlmsg_hdr(skb);
 390        char *data = nlmsg_data(nlh);
 391
 392        if (nlh->nlmsg_type != AUDIT_EOE) {
 393                if (printk_ratelimit())
 394                        printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
 395                else
 396                        audit_log_lost("printk limit exceeded\n");
 397        }
 398
 399        audit_hold_skb(skb);
 400}
 401
 402static void kauditd_send_skb(struct sk_buff *skb)
 403{
 404        int err;
 405        /* take a reference in case we can't send it and we want to hold it */
 406        skb_get(skb);
 407        err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
 408        if (err < 0) {
 409                BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
 410                printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
 411                audit_log_lost("auditd disappeared\n");
 412                audit_pid = 0;
 413                /* we might get lucky and get this in the next auditd */
 414                audit_hold_skb(skb);
 415        } else
 416                /* drop the extra reference if sent ok */
 417                consume_skb(skb);
 418}
 419
 420static int kauditd_thread(void *dummy)
 421{
 422        struct sk_buff *skb;
 423
 424        set_freezable();
 425        while (!kthread_should_stop()) {
 426                /*
 427                 * if auditd just started drain the queue of messages already
 428                 * sent to syslog/printk.  remember loss here is ok.  we already
 429                 * called audit_log_lost() if it didn't go out normally.  so the
 430                 * race between the skb_dequeue and the next check for audit_pid
 431                 * doesn't matter.
 432                 *
 433                 * if you ever find kauditd to be too slow we can get a perf win
 434                 * by doing our own locking and keeping better track if there
 435                 * are messages in this queue.  I don't see the need now, but
 436                 * in 5 years when I want to play with this again I'll see this
 437                 * note and still have no friggin idea what i'm thinking today.
 438                 */
 439                if (audit_default && audit_pid) {
 440                        skb = skb_dequeue(&audit_skb_hold_queue);
 441                        if (unlikely(skb)) {
 442                                while (skb && audit_pid) {
 443                                        kauditd_send_skb(skb);
 444                                        skb = skb_dequeue(&audit_skb_hold_queue);
 445                                }
 446                        }
 447                }
 448
 449                skb = skb_dequeue(&audit_skb_queue);
 450                wake_up(&audit_backlog_wait);
 451                if (skb) {
 452                        if (audit_pid)
 453                                kauditd_send_skb(skb);
 454                        else
 455                                audit_printk_skb(skb);
 456                } else {
 457                        DECLARE_WAITQUEUE(wait, current);
 458                        set_current_state(TASK_INTERRUPTIBLE);
 459                        add_wait_queue(&kauditd_wait, &wait);
 460
 461                        if (!skb_queue_len(&audit_skb_queue)) {
 462                                try_to_freeze();
 463                                schedule();
 464                        }
 465
 466                        __set_current_state(TASK_RUNNING);
 467                        remove_wait_queue(&kauditd_wait, &wait);
 468                }
 469        }
 470        return 0;
 471}
 472
 473int audit_send_list(void *_dest)
 474{
 475        struct audit_netlink_list *dest = _dest;
 476        int pid = dest->pid;
 477        struct sk_buff *skb;
 478
 479        /* wait for parent to finish and send an ACK */
 480        mutex_lock(&audit_cmd_mutex);
 481        mutex_unlock(&audit_cmd_mutex);
 482
 483        while ((skb = __skb_dequeue(&dest->q)) != NULL)
 484                netlink_unicast(audit_sock, skb, pid, 0);
 485
 486        kfree(dest);
 487
 488        return 0;
 489}
 490
 491struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
 492                                 int multi, const void *payload, int size)
 493{
 494        struct sk_buff  *skb;
 495        struct nlmsghdr *nlh;
 496        void            *data;
 497        int             flags = multi ? NLM_F_MULTI : 0;
 498        int             t     = done  ? NLMSG_DONE  : type;
 499
 500        skb = nlmsg_new(size, GFP_KERNEL);
 501        if (!skb)
 502                return NULL;
 503
 504        nlh     = nlmsg_put(skb, pid, seq, t, size, flags);
 505        if (!nlh)
 506                goto out_kfree_skb;
 507        data = nlmsg_data(nlh);
 508        memcpy(data, payload, size);
 509        return skb;
 510
 511out_kfree_skb:
 512        kfree_skb(skb);
 513        return NULL;
 514}
 515
 516static int audit_send_reply_thread(void *arg)
 517{
 518        struct audit_reply *reply = (struct audit_reply *)arg;
 519
 520        mutex_lock(&audit_cmd_mutex);
 521        mutex_unlock(&audit_cmd_mutex);
 522
 523        /* Ignore failure. It'll only happen if the sender goes away,
 524           because our timeout is set to infinite. */
 525        netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
 526        kfree(reply);
 527        return 0;
 528}
 529/**
 530 * audit_send_reply - send an audit reply message via netlink
 531 * @pid: process id to send reply to
 532 * @seq: sequence number
 533 * @type: audit message type
 534 * @done: done (last) flag
 535 * @multi: multi-part message flag
 536 * @payload: payload data
 537 * @size: payload size
 538 *
 539 * Allocates an skb, builds the netlink message, and sends it to the pid.
 540 * No failure notifications.
 541 */
 542static void audit_send_reply(int pid, int seq, int type, int done, int multi,
 543                             const void *payload, int size)
 544{
 545        struct sk_buff *skb;
 546        struct task_struct *tsk;
 547        struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
 548                                            GFP_KERNEL);
 549
 550        if (!reply)
 551                return;
 552
 553        skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
 554        if (!skb)
 555                goto out;
 556
 557        reply->pid = pid;
 558        reply->skb = skb;
 559
 560        tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
 561        if (!IS_ERR(tsk))
 562                return;
 563        kfree_skb(skb);
 564out:
 565        kfree(reply);
 566}
 567
 568/*
 569 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 570 * control messages.
 571 */
 572static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 573{
 574        int err = 0;
 575
 576        /* Only support the initial namespaces for now. */
 577        if ((current_user_ns() != &init_user_ns) ||
 578            (task_active_pid_ns(current) != &init_pid_ns))
 579                return -EPERM;
 580
 581        switch (msg_type) {
 582        case AUDIT_GET:
 583        case AUDIT_LIST:
 584        case AUDIT_LIST_RULES:
 585        case AUDIT_SET:
 586        case AUDIT_ADD:
 587        case AUDIT_ADD_RULE:
 588        case AUDIT_DEL:
 589        case AUDIT_DEL_RULE:
 590        case AUDIT_SIGNAL_INFO:
 591        case AUDIT_TTY_GET:
 592        case AUDIT_TTY_SET:
 593        case AUDIT_TRIM:
 594        case AUDIT_MAKE_EQUIV:
 595                if (!capable(CAP_AUDIT_CONTROL))
 596                        err = -EPERM;
 597                break;
 598        case AUDIT_USER:
 599        case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 600        case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 601                if (!capable(CAP_AUDIT_WRITE))
 602                        err = -EPERM;
 603                break;
 604        default:  /* bad msg */
 605                err = -EINVAL;
 606        }
 607
 608        return err;
 609}
 610
 611static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
 612                                     kuid_t auid, u32 ses, u32 sid)
 613{
 614        int rc = 0;
 615        char *ctx = NULL;
 616        u32 len;
 617
 618        if (!audit_enabled) {
 619                *ab = NULL;
 620                return rc;
 621        }
 622
 623        *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 624        if (unlikely(!*ab))
 625                return rc;
 626        audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
 627                         task_tgid_vnr(current),
 628                         from_kuid(&init_user_ns, current_uid()),
 629                         from_kuid(&init_user_ns, auid), ses);
 630        if (sid) {
 631                rc = security_secid_to_secctx(sid, &ctx, &len);
 632                if (rc)
 633                        audit_log_format(*ab, " ssid=%u", sid);
 634                else {
 635                        audit_log_format(*ab, " subj=%s", ctx);
 636                        security_release_secctx(ctx, len);
 637                }
 638        }
 639
 640        return rc;
 641}
 642
 643static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 644{
 645        u32                     seq, sid;
 646        void                    *data;
 647        struct audit_status     *status_get, status_set;
 648        int                     err;
 649        struct audit_buffer     *ab;
 650        u16                     msg_type = nlh->nlmsg_type;
 651        kuid_t                  loginuid; /* loginuid of sender */
 652        u32                     sessionid;
 653        struct audit_sig_info   *sig_data;
 654        char                    *ctx = NULL;
 655        u32                     len;
 656
 657        err = audit_netlink_ok(skb, msg_type);
 658        if (err)
 659                return err;
 660
 661        /* As soon as there's any sign of userspace auditd,
 662         * start kauditd to talk to it */
 663        if (!kauditd_task)
 664                kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 665        if (IS_ERR(kauditd_task)) {
 666                err = PTR_ERR(kauditd_task);
 667                kauditd_task = NULL;
 668                return err;
 669        }
 670
 671        loginuid = audit_get_loginuid(current);
 672        sessionid = audit_get_sessionid(current);
 673        security_task_getsecid(current, &sid);
 674        seq  = nlh->nlmsg_seq;
 675        data = nlmsg_data(nlh);
 676
 677        switch (msg_type) {
 678        case AUDIT_GET:
 679                status_set.enabled       = audit_enabled;
 680                status_set.failure       = audit_failure;
 681                status_set.pid           = audit_pid;
 682                status_set.rate_limit    = audit_rate_limit;
 683                status_set.backlog_limit = audit_backlog_limit;
 684                status_set.lost          = atomic_read(&audit_lost);
 685                status_set.backlog       = skb_queue_len(&audit_skb_queue);
 686                audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
 687                                 &status_set, sizeof(status_set));
 688                break;
 689        case AUDIT_SET:
 690                if (nlh->nlmsg_len < sizeof(struct audit_status))
 691                        return -EINVAL;
 692                status_get   = (struct audit_status *)data;
 693                if (status_get->mask & AUDIT_STATUS_ENABLED) {
 694                        err = audit_set_enabled(status_get->enabled,
 695                                                loginuid, sessionid, sid);
 696                        if (err < 0)
 697                                return err;
 698                }
 699                if (status_get->mask & AUDIT_STATUS_FAILURE) {
 700                        err = audit_set_failure(status_get->failure,
 701                                                loginuid, sessionid, sid);
 702                        if (err < 0)
 703                                return err;
 704                }
 705                if (status_get->mask & AUDIT_STATUS_PID) {
 706                        int new_pid = status_get->pid;
 707
 708                        if (audit_enabled != AUDIT_OFF)
 709                                audit_log_config_change("audit_pid", new_pid,
 710                                                        audit_pid, loginuid,
 711                                                        sessionid, sid, 1);
 712
 713                        audit_pid = new_pid;
 714                        audit_nlk_portid = NETLINK_CB(skb).portid;
 715                }
 716                if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
 717                        err = audit_set_rate_limit(status_get->rate_limit,
 718                                                   loginuid, sessionid, sid);
 719                        if (err < 0)
 720                                return err;
 721                }
 722                if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
 723                        err = audit_set_backlog_limit(status_get->backlog_limit,
 724                                                      loginuid, sessionid, sid);
 725                break;
 726        case AUDIT_USER:
 727        case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
 728        case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
 729                if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 730                        return 0;
 731
 732                err = audit_filter_user();
 733                if (err == 1) {
 734                        err = 0;
 735                        if (msg_type == AUDIT_USER_TTY) {
 736                                err = tty_audit_push_task(current, loginuid,
 737                                                             sessionid);
 738                                if (err)
 739                                        break;
 740                        }
 741                        audit_log_common_recv_msg(&ab, msg_type,
 742                                                  loginuid, sessionid, sid);
 743
 744                        if (msg_type != AUDIT_USER_TTY)
 745                                audit_log_format(ab, " msg='%.1024s'",
 746                                                 (char *)data);
 747                        else {
 748                                int size;
 749
 750                                audit_log_format(ab, " msg=");
 751                                size = nlmsg_len(nlh);
 752                                if (size > 0 &&
 753                                    ((unsigned char *)data)[size - 1] == '\0')
 754                                        size--;
 755                                audit_log_n_untrustedstring(ab, data, size);
 756                        }
 757                        audit_set_pid(ab, NETLINK_CB(skb).portid);
 758                        audit_log_end(ab);
 759                }
 760                break;
 761        case AUDIT_ADD:
 762        case AUDIT_DEL:
 763                if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 764                        return -EINVAL;
 765                if (audit_enabled == AUDIT_LOCKED) {
 766                        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
 767                                                  loginuid, sessionid, sid);
 768
 769                        audit_log_format(ab, " audit_enabled=%d res=0",
 770                                         audit_enabled);
 771                        audit_log_end(ab);
 772                        return -EPERM;
 773                }
 774                /* fallthrough */
 775        case AUDIT_LIST:
 776                err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
 777                                           seq, data, nlmsg_len(nlh),
 778                                           loginuid, sessionid, sid);
 779                break;
 780        case AUDIT_ADD_RULE:
 781        case AUDIT_DEL_RULE:
 782                if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 783                        return -EINVAL;
 784                if (audit_enabled == AUDIT_LOCKED) {
 785                        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
 786                                                  loginuid, sessionid, sid);
 787
 788                        audit_log_format(ab, " audit_enabled=%d res=0",
 789                                         audit_enabled);
 790                        audit_log_end(ab);
 791                        return -EPERM;
 792                }
 793                /* fallthrough */
 794        case AUDIT_LIST_RULES:
 795                err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
 796                                           seq, data, nlmsg_len(nlh),
 797                                           loginuid, sessionid, sid);
 798                break;
 799        case AUDIT_TRIM:
 800                audit_trim_trees();
 801
 802                audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
 803                                          loginuid, sessionid, sid);
 804
 805                audit_log_format(ab, " op=trim res=1");
 806                audit_log_end(ab);
 807                break;
 808        case AUDIT_MAKE_EQUIV: {
 809                void *bufp = data;
 810                u32 sizes[2];
 811                size_t msglen = nlmsg_len(nlh);
 812                char *old, *new;
 813
 814                err = -EINVAL;
 815                if (msglen < 2 * sizeof(u32))
 816                        break;
 817                memcpy(sizes, bufp, 2 * sizeof(u32));
 818                bufp += 2 * sizeof(u32);
 819                msglen -= 2 * sizeof(u32);
 820                old = audit_unpack_string(&bufp, &msglen, sizes[0]);
 821                if (IS_ERR(old)) {
 822                        err = PTR_ERR(old);
 823                        break;
 824                }
 825                new = audit_unpack_string(&bufp, &msglen, sizes[1]);
 826                if (IS_ERR(new)) {
 827                        err = PTR_ERR(new);
 828                        kfree(old);
 829                        break;
 830                }
 831                /* OK, here comes... */
 832                err = audit_tag_tree(old, new);
 833
 834                audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE,
 835                                          loginuid, sessionid, sid);
 836
 837                audit_log_format(ab, " op=make_equiv old=");
 838                audit_log_untrustedstring(ab, old);
 839                audit_log_format(ab, " new=");
 840                audit_log_untrustedstring(ab, new);
 841                audit_log_format(ab, " res=%d", !err);
 842                audit_log_end(ab);
 843                kfree(old);
 844                kfree(new);
 845                break;
 846        }
 847        case AUDIT_SIGNAL_INFO:
 848                len = 0;
 849                if (audit_sig_sid) {
 850                        err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
 851                        if (err)
 852                                return err;
 853                }
 854                sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 855                if (!sig_data) {
 856                        if (audit_sig_sid)
 857                                security_release_secctx(ctx, len);
 858                        return -ENOMEM;
 859                }
 860                sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
 861                sig_data->pid = audit_sig_pid;
 862                if (audit_sig_sid) {
 863                        memcpy(sig_data->ctx, ctx, len);
 864                        security_release_secctx(ctx, len);
 865                }
 866                audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO,
 867                                0, 0, sig_data, sizeof(*sig_data) + len);
 868                kfree(sig_data);
 869                break;
 870        case AUDIT_TTY_GET: {
 871                struct audit_tty_status s;
 872                struct task_struct *tsk = current;
 873
 874                spin_lock_irq(&tsk->sighand->siglock);
 875                s.enabled = tsk->signal->audit_tty != 0;
 876                spin_unlock_irq(&tsk->sighand->siglock);
 877
 878                audit_send_reply(NETLINK_CB(skb).portid, seq,
 879                                 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
 880                break;
 881        }
 882        case AUDIT_TTY_SET: {
 883                struct audit_tty_status *s;
 884                struct task_struct *tsk = current;
 885
 886                if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
 887                        return -EINVAL;
 888                s = data;
 889                if (s->enabled != 0 && s->enabled != 1)
 890                        return -EINVAL;
 891
 892                spin_lock_irq(&tsk->sighand->siglock);
 893                tsk->signal->audit_tty = s->enabled != 0;
 894                spin_unlock_irq(&tsk->sighand->siglock);
 895                break;
 896        }
 897        default:
 898                err = -EINVAL;
 899                break;
 900        }
 901
 902        return err < 0 ? err : 0;
 903}
 904
 905/*
 906 * Get message from skb.  Each message is processed by audit_receive_msg.
 907 * Malformed skbs with wrong length are discarded silently.
 908 */
 909static void audit_receive_skb(struct sk_buff *skb)
 910{
 911        struct nlmsghdr *nlh;
 912        /*
 913         * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
 914         * if the nlmsg_len was not aligned
 915         */
 916        int len;
 917        int err;
 918
 919        nlh = nlmsg_hdr(skb);
 920        len = skb->len;
 921
 922        while (NLMSG_OK(nlh, len)) {
 923                err = audit_receive_msg(skb, nlh);
 924                /* if err or if this message says it wants a response */
 925                if (err || (nlh->nlmsg_flags & NLM_F_ACK))
 926                        netlink_ack(skb, nlh, err);
 927
 928                nlh = NLMSG_NEXT(nlh, len);
 929        }
 930}
 931
 932/* Receive messages from netlink socket. */
 933static void audit_receive(struct sk_buff  *skb)
 934{
 935        mutex_lock(&audit_cmd_mutex);
 936        audit_receive_skb(skb);
 937        mutex_unlock(&audit_cmd_mutex);
 938}
 939
 940/* Initialize audit support at boot time. */
 941static int __init audit_init(void)
 942{
 943        int i;
 944        struct netlink_kernel_cfg cfg = {
 945                .input  = audit_receive,
 946        };
 947
 948        if (audit_initialized == AUDIT_DISABLED)
 949                return 0;
 950
 951        printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
 952               audit_default ? "enabled" : "disabled");
 953        audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
 954        if (!audit_sock)
 955                audit_panic("cannot initialize netlink socket");
 956        else
 957                audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
 958
 959        skb_queue_head_init(&audit_skb_queue);
 960        skb_queue_head_init(&audit_skb_hold_queue);
 961        audit_initialized = AUDIT_INITIALIZED;
 962        audit_enabled = audit_default;
 963        audit_ever_enabled |= !!audit_default;
 964
 965        audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
 966
 967        for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
 968                INIT_LIST_HEAD(&audit_inode_hash[i]);
 969
 970        return 0;
 971}
 972__initcall(audit_init);
 973
 974/* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
 975static int __init audit_enable(char *str)
 976{
 977        audit_default = !!simple_strtol(str, NULL, 0);
 978        if (!audit_default)
 979                audit_initialized = AUDIT_DISABLED;
 980
 981        printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
 982
 983        if (audit_initialized == AUDIT_INITIALIZED) {
 984                audit_enabled = audit_default;
 985                audit_ever_enabled |= !!audit_default;
 986        } else if (audit_initialized == AUDIT_UNINITIALIZED) {
 987                printk(" (after initialization)");
 988        } else {
 989                printk(" (until reboot)");
 990        }
 991        printk("\n");
 992
 993        return 1;
 994}
 995
 996__setup("audit=", audit_enable);
 997
 998static void audit_buffer_free(struct audit_buffer *ab)
 999{
1000        unsigned long flags;
1001
1002        if (!ab)
1003                return;
1004
1005        if (ab->skb)
1006                kfree_skb(ab->skb);
1007
1008        spin_lock_irqsave(&audit_freelist_lock, flags);
1009        if (audit_freelist_count > AUDIT_MAXFREE)
1010                kfree(ab);
1011        else {
1012                audit_freelist_count++;
1013                list_add(&ab->list, &audit_freelist);
1014        }
1015        spin_unlock_irqrestore(&audit_freelist_lock, flags);
1016}
1017
1018static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1019                                                gfp_t gfp_mask, int type)
1020{
1021        unsigned long flags;
1022        struct audit_buffer *ab = NULL;
1023        struct nlmsghdr *nlh;
1024
1025        spin_lock_irqsave(&audit_freelist_lock, flags);
1026        if (!list_empty(&audit_freelist)) {
1027                ab = list_entry(audit_freelist.next,
1028                                struct audit_buffer, list);
1029                list_del(&ab->list);
1030                --audit_freelist_count;
1031        }
1032        spin_unlock_irqrestore(&audit_freelist_lock, flags);
1033
1034        if (!ab) {
1035                ab = kmalloc(sizeof(*ab), gfp_mask);
1036                if (!ab)
1037                        goto err;
1038        }
1039
1040        ab->ctx = ctx;
1041        ab->gfp_mask = gfp_mask;
1042
1043        ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1044        if (!ab->skb)
1045                goto err;
1046
1047        nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1048        if (!nlh)
1049                goto out_kfree_skb;
1050
1051        return ab;
1052
1053out_kfree_skb:
1054        kfree_skb(ab->skb);
1055        ab->skb = NULL;
1056err:
1057        audit_buffer_free(ab);
1058        return NULL;
1059}
1060
1061/**
1062 * audit_serial - compute a serial number for the audit record
1063 *
1064 * Compute a serial number for the audit record.  Audit records are
1065 * written to user-space as soon as they are generated, so a complete
1066 * audit record may be written in several pieces.  The timestamp of the
1067 * record and this serial number are used by the user-space tools to
1068 * determine which pieces belong to the same audit record.  The
1069 * (timestamp,serial) tuple is unique for each syscall and is live from
1070 * syscall entry to syscall exit.
1071 *
1072 * NOTE: Another possibility is to store the formatted records off the
1073 * audit context (for those records that have a context), and emit them
1074 * all at syscall exit.  However, this could delay the reporting of
1075 * significant errors until syscall exit (or never, if the system
1076 * halts).
1077 */
1078unsigned int audit_serial(void)
1079{
1080        static DEFINE_SPINLOCK(serial_lock);
1081        static unsigned int serial = 0;
1082
1083        unsigned long flags;
1084        unsigned int ret;
1085
1086        spin_lock_irqsave(&serial_lock, flags);
1087        do {
1088                ret = ++serial;
1089        } while (unlikely(!ret));
1090        spin_unlock_irqrestore(&serial_lock, flags);
1091
1092        return ret;
1093}
1094
1095static inline void audit_get_stamp(struct audit_context *ctx,
1096                                   struct timespec *t, unsigned int *serial)
1097{
1098        if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1099                *t = CURRENT_TIME;
1100                *serial = audit_serial();
1101        }
1102}
1103
1104/*
1105 * Wait for auditd to drain the queue a little
1106 */
1107static void wait_for_auditd(unsigned long sleep_time)
1108{
1109        DECLARE_WAITQUEUE(wait, current);
1110        set_current_state(TASK_INTERRUPTIBLE);
1111        add_wait_queue(&audit_backlog_wait, &wait);
1112
1113        if (audit_backlog_limit &&
1114            skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1115                schedule_timeout(sleep_time);
1116
1117        __set_current_state(TASK_RUNNING);
1118        remove_wait_queue(&audit_backlog_wait, &wait);
1119}
1120
1121/* Obtain an audit buffer.  This routine does locking to obtain the
1122 * audit buffer, but then no locking is required for calls to
1123 * audit_log_*format.  If the tsk is a task that is currently in a
1124 * syscall, then the syscall is marked as auditable and an audit record
1125 * will be written at syscall exit.  If there is no associated task, tsk
1126 * should be NULL. */
1127
1128/**
1129 * audit_log_start - obtain an audit buffer
1130 * @ctx: audit_context (may be NULL)
1131 * @gfp_mask: type of allocation
1132 * @type: audit message type
1133 *
1134 * Returns audit_buffer pointer on success or NULL on error.
1135 *
1136 * Obtain an audit buffer.  This routine does locking to obtain the
1137 * audit buffer, but then no locking is required for calls to
1138 * audit_log_*format.  If the task (ctx) is a task that is currently in a
1139 * syscall, then the syscall is marked as auditable and an audit record
1140 * will be written at syscall exit.  If there is no associated task, then
1141 * task context (ctx) should be NULL.
1142 */
1143struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1144                                     int type)
1145{
1146        struct audit_buffer     *ab     = NULL;
1147        struct timespec         t;
1148        unsigned int            uninitialized_var(serial);
1149        int reserve;
1150        unsigned long timeout_start = jiffies;
1151
1152        if (audit_initialized != AUDIT_INITIALIZED)
1153                return NULL;
1154
1155        if (unlikely(audit_filter_type(type)))
1156                return NULL;
1157
1158        if (gfp_mask & __GFP_WAIT)
1159                reserve = 0;
1160        else
1161                reserve = 5; /* Allow atomic callers to go up to five
1162                                entries over the normal backlog limit */
1163
1164        while (audit_backlog_limit
1165               && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1166                if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
1167                        unsigned long sleep_time;
1168
1169                        sleep_time = timeout_start + audit_backlog_wait_time -
1170                                        jiffies;
1171                        if ((long)sleep_time > 0)
1172                                wait_for_auditd(sleep_time);
1173                        continue;
1174                }
1175                if (audit_rate_check() && printk_ratelimit())
1176                        printk(KERN_WARNING
1177                               "audit: audit_backlog=%d > "
1178                               "audit_backlog_limit=%d\n",
1179                               skb_queue_len(&audit_skb_queue),
1180                               audit_backlog_limit);
1181                audit_log_lost("backlog limit exceeded");
1182                audit_backlog_wait_time = audit_backlog_wait_overflow;
1183                wake_up(&audit_backlog_wait);
1184                return NULL;
1185        }
1186
1187        ab = audit_buffer_alloc(ctx, gfp_mask, type);
1188        if (!ab) {
1189                audit_log_lost("out of memory in audit_log_start");
1190                return NULL;
1191        }
1192
1193        audit_get_stamp(ab->ctx, &t, &serial);
1194
1195        audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1196                         t.tv_sec, t.tv_nsec/1000000, serial);
1197        return ab;
1198}
1199
1200/**
1201 * audit_expand - expand skb in the audit buffer
1202 * @ab: audit_buffer
1203 * @extra: space to add at tail of the skb
1204 *
1205 * Returns 0 (no space) on failed expansion, or available space if
1206 * successful.
1207 */
1208static inline int audit_expand(struct audit_buffer *ab, int extra)
1209{
1210        struct sk_buff *skb = ab->skb;
1211        int oldtail = skb_tailroom(skb);
1212        int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1213        int newtail = skb_tailroom(skb);
1214
1215        if (ret < 0) {
1216                audit_log_lost("out of memory in audit_expand");
1217                return 0;
1218        }
1219
1220        skb->truesize += newtail - oldtail;
1221        return newtail;
1222}
1223
1224/*
1225 * Format an audit message into the audit buffer.  If there isn't enough
1226 * room in the audit buffer, more room will be allocated and vsnprint
1227 * will be called a second time.  Currently, we assume that a printk
1228 * can't format message larger than 1024 bytes, so we don't either.
1229 */
1230static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1231                              va_list args)
1232{
1233        int len, avail;
1234        struct sk_buff *skb;
1235        va_list args2;
1236
1237        if (!ab)
1238                return;
1239
1240        BUG_ON(!ab->skb);
1241        skb = ab->skb;
1242        avail = skb_tailroom(skb);
1243        if (avail == 0) {
1244                avail = audit_expand(ab, AUDIT_BUFSIZ);
1245                if (!avail)
1246                        goto out;
1247        }
1248        va_copy(args2, args);
1249        len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1250        if (len >= avail) {
1251                /* The printk buffer is 1024 bytes long, so if we get
1252                 * here and AUDIT_BUFSIZ is at least 1024, then we can
1253                 * log everything that printk could have logged. */
1254                avail = audit_expand(ab,
1255                        max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1256                if (!avail)
1257                        goto out_va_end;
1258                len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1259        }
1260        if (len > 0)
1261                skb_put(skb, len);
1262out_va_end:
1263        va_end(args2);
1264out:
1265        return;
1266}
1267
1268/**
1269 * audit_log_format - format a message into the audit buffer.
1270 * @ab: audit_buffer
1271 * @fmt: format string
1272 * @...: optional parameters matching @fmt string
1273 *
1274 * All the work is done in audit_log_vformat.
1275 */
1276void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1277{
1278        va_list args;
1279
1280        if (!ab)
1281                return;
1282        va_start(args, fmt);
1283        audit_log_vformat(ab, fmt, args);
1284        va_end(args);
1285}
1286
1287/**
1288 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1289 * @ab: the audit_buffer
1290 * @buf: buffer to convert to hex
1291 * @len: length of @buf to be converted
1292 *
1293 * No return value; failure to expand is silently ignored.
1294 *
1295 * This function will take the passed buf and convert it into a string of
1296 * ascii hex digits. The new string is placed onto the skb.
1297 */
1298void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1299                size_t len)
1300{
1301        int i, avail, new_len;
1302        unsigned char *ptr;
1303        struct sk_buff *skb;
1304        static const unsigned char *hex = "0123456789ABCDEF";
1305
1306        if (!ab)
1307                return;
1308
1309        BUG_ON(!ab->skb);
1310        skb = ab->skb;
1311        avail = skb_tailroom(skb);
1312        new_len = len<<1;
1313        if (new_len >= avail) {
1314                /* Round the buffer request up to the next multiple */
1315                new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1316                avail = audit_expand(ab, new_len);
1317                if (!avail)
1318                        return;
1319        }
1320
1321        ptr = skb_tail_pointer(skb);
1322        for (i=0; i<len; i++) {
1323                *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1324                *ptr++ = hex[buf[i] & 0x0F];      /* Lower nibble */
1325        }
1326        *ptr = 0;
1327        skb_put(skb, len << 1); /* new string is twice the old string */
1328}
1329
1330/*
1331 * Format a string of no more than slen characters into the audit buffer,
1332 * enclosed in quote marks.
1333 */
1334void audit_log_n_string(struct audit_buffer *ab, const char *string,
1335                        size_t slen)
1336{
1337        int avail, new_len;
1338        unsigned char *ptr;
1339        struct sk_buff *skb;
1340
1341        if (!ab)
1342                return;
1343
1344        BUG_ON(!ab->skb);
1345        skb = ab->skb;
1346        avail = skb_tailroom(skb);
1347        new_len = slen + 3;     /* enclosing quotes + null terminator */
1348        if (new_len > avail) {
1349                avail = audit_expand(ab, new_len);
1350                if (!avail)
1351                        return;
1352        }
1353        ptr = skb_tail_pointer(skb);
1354        *ptr++ = '"';
1355        memcpy(ptr, string, slen);
1356        ptr += slen;
1357        *ptr++ = '"';
1358        *ptr = 0;
1359        skb_put(skb, slen + 2); /* don't include null terminator */
1360}
1361
1362/**
1363 * audit_string_contains_control - does a string need to be logged in hex
1364 * @string: string to be checked
1365 * @len: max length of the string to check
1366 */
1367int audit_string_contains_control(const char *string, size_t len)
1368{
1369        const unsigned char *p;
1370        for (p = string; p < (const unsigned char *)string + len; p++) {
1371                if (*p == '"' || *p < 0x21 || *p > 0x7e)
1372                        return 1;
1373        }
1374        return 0;
1375}
1376
1377/**
1378 * audit_log_n_untrustedstring - log a string that may contain random characters
1379 * @ab: audit_buffer
1380 * @len: length of string (not including trailing null)
1381 * @string: string to be logged
1382 *
1383 * This code will escape a string that is passed to it if the string
1384 * contains a control character, unprintable character, double quote mark,
1385 * or a space. Unescaped strings will start and end with a double quote mark.
1386 * Strings that are escaped are printed in hex (2 digits per char).
1387 *
1388 * The caller specifies the number of characters in the string to log, which may
1389 * or may not be the entire string.
1390 */
1391void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1392                                 size_t len)
1393{
1394        if (audit_string_contains_control(string, len))
1395                audit_log_n_hex(ab, string, len);
1396        else
1397                audit_log_n_string(ab, string, len);
1398}
1399
1400/**
1401 * audit_log_untrustedstring - log a string that may contain random characters
1402 * @ab: audit_buffer
1403 * @string: string to be logged
1404 *
1405 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1406 * determine string length.
1407 */
1408void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1409{
1410        audit_log_n_untrustedstring(ab, string, strlen(string));
1411}
1412
1413/* This is a helper-function to print the escaped d_path */
1414void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1415                      const struct path *path)
1416{
1417        char *p, *pathname;
1418
1419        if (prefix)
1420                audit_log_format(ab, "%s", prefix);
1421
1422        /* We will allow 11 spaces for ' (deleted)' to be appended */
1423        pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1424        if (!pathname) {
1425                audit_log_string(ab, "<no_memory>");
1426                return;
1427        }
1428        p = d_path(path, pathname, PATH_MAX+11);
1429        if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1430                /* FIXME: can we save some information here? */
1431                audit_log_string(ab, "<too_long>");
1432        } else
1433                audit_log_untrustedstring(ab, p);
1434        kfree(pathname);
1435}
1436
1437void audit_log_key(struct audit_buffer *ab, char *key)
1438{
1439        audit_log_format(ab, " key=");
1440        if (key)
1441                audit_log_untrustedstring(ab, key);
1442        else
1443                audit_log_format(ab, "(null)");
1444}
1445
1446/**
1447 * audit_log_link_denied - report a link restriction denial
1448 * @operation: specific link opreation
1449 * @link: the path that triggered the restriction
1450 */
1451void audit_log_link_denied(const char *operation, struct path *link)
1452{
1453        struct audit_buffer *ab;
1454
1455        ab = audit_log_start(current->audit_context, GFP_KERNEL,
1456                             AUDIT_ANOM_LINK);
1457        if (!ab)
1458                return;
1459        audit_log_format(ab, "op=%s action=denied", operation);
1460        audit_log_format(ab, " pid=%d comm=", current->pid);
1461        audit_log_untrustedstring(ab, current->comm);
1462        audit_log_d_path(ab, " path=", link);
1463        audit_log_format(ab, " dev=");
1464        audit_log_untrustedstring(ab, link->dentry->d_inode->i_sb->s_id);
1465        audit_log_format(ab, " ino=%lu", link->dentry->d_inode->i_ino);
1466        audit_log_end(ab);
1467}
1468
1469/**
1470 * audit_log_end - end one audit record
1471 * @ab: the audit_buffer
1472 *
1473 * The netlink_* functions cannot be called inside an irq context, so
1474 * the audit buffer is placed on a queue and a tasklet is scheduled to
1475 * remove them from the queue outside the irq context.  May be called in
1476 * any context.
1477 */
1478void audit_log_end(struct audit_buffer *ab)
1479{
1480        if (!ab)
1481                return;
1482        if (!audit_rate_check()) {
1483                audit_log_lost("rate limit exceeded");
1484        } else {
1485                struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1486                nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1487
1488                if (audit_pid) {
1489                        skb_queue_tail(&audit_skb_queue, ab->skb);
1490                        wake_up_interruptible(&kauditd_wait);
1491                } else {
1492                        audit_printk_skb(ab->skb);
1493                }
1494                ab->skb = NULL;
1495        }
1496        audit_buffer_free(ab);
1497}
1498
1499/**
1500 * audit_log - Log an audit record
1501 * @ctx: audit context
1502 * @gfp_mask: type of allocation
1503 * @type: audit message type
1504 * @fmt: format string to use
1505 * @...: variable parameters matching the format string
1506 *
1507 * This is a convenience function that calls audit_log_start,
1508 * audit_log_vformat, and audit_log_end.  It may be called
1509 * in any context.
1510 */
1511void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1512               const char *fmt, ...)
1513{
1514        struct audit_buffer *ab;
1515        va_list args;
1516
1517        ab = audit_log_start(ctx, gfp_mask, type);
1518        if (ab) {
1519                va_start(args, fmt);
1520                audit_log_vformat(ab, fmt, args);
1521                va_end(args);
1522                audit_log_end(ab);
1523        }
1524}
1525
1526#ifdef CONFIG_SECURITY
1527/**
1528 * audit_log_secctx - Converts and logs SELinux context
1529 * @ab: audit_buffer
1530 * @secid: security number
1531 *
1532 * This is a helper function that calls security_secid_to_secctx to convert
1533 * secid to secctx and then adds the (converted) SELinux context to the audit
1534 * log by calling audit_log_format, thus also preventing leak of internal secid
1535 * to userspace. If secid cannot be converted audit_panic is called.
1536 */
1537void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1538{
1539        u32 len;
1540        char *secctx;
1541
1542        if (security_secid_to_secctx(secid, &secctx, &len)) {
1543                audit_panic("Cannot convert secid to context");
1544        } else {
1545                audit_log_format(ab, " obj=%s", secctx);
1546                security_release_secctx(secctx, len);
1547        }
1548}
1549EXPORT_SYMBOL(audit_log_secctx);
1550#endif
1551
1552EXPORT_SYMBOL(audit_log_start);
1553EXPORT_SYMBOL(audit_log_end);
1554EXPORT_SYMBOL(audit_log_format);
1555EXPORT_SYMBOL(audit_log);
1556
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