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