kernel/audit.c

   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 2003-2004 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 SELinux.
  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 <asm/atomic.h>
  47 #include <linux/mm.h>
  48 #include <linux/module.h>
  49 #include <linux/err.h>
  50 #include <linux/kthread.h>
  51
  52 #include <linux/audit.h>
  53
  54 #include <net/sock.h>
  55 #include <net/netlink.h>
  56 #include <linux/skbuff.h>
  57 #include <linux/netlink.h>
  58 #include <linux/selinux.h>
  59 #include <linux/inotify.h>
  60
  61 #include "audit.h"
  62
  63 /* No auditing will take place until audit_initialized != 0.
  64  * (Initialization happens after skb_init is called.) */
  65 static int      audit_initialized;
  66
  67 /* No syscall auditing will take place unless audit_enabled != 0. */
  68 int             audit_enabled;
  69
  70 /* Default state when kernel boots without any parameters. */
  71 static int      audit_default;
  72
  73 /* If auditing cannot proceed, audit_failure selects what happens. */
  74 static int      audit_failure = AUDIT_FAIL_PRINTK;
  75
  76 /* If audit records are to be written to the netlink socket, audit_pid
  77  * contains the (non-zero) pid. */
  78 int             audit_pid;
  79
  80 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
  81  * to that number per second.  This prevents DoS attacks, but results in
  82  * audit records being dropped. */
  83 static int      audit_rate_limit;
  84
  85 /* Number of outstanding audit_buffers allowed. */
  86 static int      audit_backlog_limit = 64;
  87 static int      audit_backlog_wait_time = 60 * HZ;
  88 static int      audit_backlog_wait_overflow = 0;
  89
  90 /* The identity of the user shutting down the audit system. */
  91 uid_t           audit_sig_uid = -1;
  92 pid_t           audit_sig_pid = -1;
  93 u32             audit_sig_sid = 0;
  94
  95 /* Records can be lost in several ways:
  96    0) [suppressed in audit_alloc]
  97    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
  98    2) out of memory in audit_log_move [alloc_skb]
  99    3) suppressed due to audit_rate_limit
 100    4) suppressed due to audit_backlog_limit
 101 */
 102 static atomic_t    audit_lost = ATOMIC_INIT(0);
 103
 104 /* The netlink socket. */
 105 static struct sock *audit_sock;
 106
 107 /* Inotify handle. */
 108 struct inotify_handle *audit_ih;
 109
 110 /* Hash for inode-based rules */
 111 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 112
 113 /* The audit_freelist is a list of pre-allocated audit buffers (if more
 114  * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
 115  * being placed on the freelist). */
 116 static DEFINE_SPINLOCK(audit_freelist_lock);
 117 static int         audit_freelist_count;
 118 static LIST_HEAD(audit_freelist);
 119
 120 static struct sk_buff_head audit_skb_queue;
 121 static struct task_struct *kauditd_task;
 122 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 123 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 124
 125 /* Serialize requests from userspace. */
 126 static DEFINE_MUTEX(audit_cmd_mutex);
 127
 128 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 129  * audit records.  Since printk uses a 1024 byte buffer, this buffer
 130  * should be at least that large. */
 131 #define AUDIT_BUFSIZ 1024
 132
 133 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
 134  * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
 135 #define AUDIT_MAXFREE  (2*NR_CPUS)
 136
 137 /* The audit_buffer is used when formatting an audit record.  The caller
 138  * locks briefly to get the record off the freelist or to allocate the
 139  * buffer, and locks briefly to send the buffer to the netlink layer or
 140  * to place it on a transmit queue.  Multiple audit_buffers can be in
 141  * use simultaneously. */
 142 struct audit_buffer {
 143         struct list_head     list;
 144         struct sk_buff       *skb;      /* formatted skb ready to send */
 145         struct audit_context *ctx;      /* NULL or associated context */
 146         gfp_t                gfp_mask;
 147 };
 148
 149 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
 150 {
 151         struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
 152         nlh->nlmsg_pid = pid;
 153 }
 154
 155 void audit_panic(const char *message)
 156 {
 157         switch (audit_failure)
 158         {
 159         case AUDIT_FAIL_SILENT:
 160                 break;
 161         case AUDIT_FAIL_PRINTK:
 162                 printk(KERN_ERR "audit: %s\n", message);
 163                 break;
 164         case AUDIT_FAIL_PANIC:
 165                 panic("audit: %s\n", message);
 166                 break;
 167         }
 168 }
 169
 170 static inline int audit_rate_check(void)
 171 {
 172         static unsigned long    last_check = 0;
 173         static int              messages   = 0;
 174         static DEFINE_SPINLOCK(lock);
 175         unsigned long           flags;
 176         unsigned long           now;
 177         unsigned long           elapsed;
 178         int                     retval     = 0;
 179
 180         if (!audit_rate_limit) return 1;
 181
 182         spin_lock_irqsave(&lock, flags);
 183         if (++messages < audit_rate_limit) {
 184                 retval = 1;
 185         } else {
 186                 now     = jiffies;
 187                 elapsed = now - last_check;
 188                 if (elapsed > HZ) {
 189                         last_check = now;
 190                         messages   = 0;
 191                         retval     = 1;
 192                 }
 193         }
 194         spin_unlock_irqrestore(&lock, flags);
 195
 196         return retval;
 197 }
 198
 199 /**
 200  * audit_log_lost - conditionally log lost audit message event
 201  * @message: the message stating reason for lost audit message
 202  *
 203  * Emit at least 1 message per second, even if audit_rate_check is
 204  * throttling.
 205  * Always increment the lost messages counter.
 206 */
 207 void audit_log_lost(const char *message)
 208 {
 209         static unsigned long    last_msg = 0;
 210         static DEFINE_SPINLOCK(lock);
 211         unsigned long           flags;
 212         unsigned long           now;
 213         int                     print;
 214
 215         atomic_inc(&audit_lost);
 216
 217         print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 218
 219         if (!print) {
 220                 spin_lock_irqsave(&lock, flags);
 221                 now = jiffies;
 222                 if (now - last_msg > HZ) {
 223                         print = 1;
 224                         last_msg = now;
 225                 }
 226                 spin_unlock_irqrestore(&lock, flags);
 227         }
 228
 229         if (print) {
 230                 printk(KERN_WARNING
 231                        "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n",
 232                        atomic_read(&audit_lost),
 233                        audit_rate_limit,
 234                        audit_backlog_limit);
 235                 audit_panic(message);
 236         }
 237 }
 238
 239 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
 240 {
 241         int old = audit_rate_limit;
 242
 243         if (sid) {
 244                 char *ctx = NULL;
 245                 u32 len;
 246                 int rc;
 247                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 248                         return rc;
 249                 else
 250                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 251                                 "audit_rate_limit=%d old=%d by auid=%u subj=%s",
 252                                 limit, old, loginuid, ctx);
 253                 kfree(ctx);
 254         } else
 255                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 256                         "audit_rate_limit=%d old=%d by auid=%u",
 257                         limit, old, loginuid);
 258         audit_rate_limit = limit;
 259         return 0;
 260 }
 261
 262 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
 263 {
 264         int old = audit_backlog_limit;
 265
 266         if (sid) {
 267                 char *ctx = NULL;
 268                 u32 len;
 269                 int rc;
 270                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 271                         return rc;
 272                 else
 273                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 274                             "audit_backlog_limit=%d old=%d by auid=%u subj=%s",
 275                                 limit, old, loginuid, ctx);
 276                 kfree(ctx);
 277         } else
 278                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 279                         "audit_backlog_limit=%d old=%d by auid=%u",
 280                         limit, old, loginuid);
 281         audit_backlog_limit = limit;
 282         return 0;
 283 }
 284
 285 static int audit_set_enabled(int state, uid_t loginuid, u32 sid)
 286 {
 287         int old = audit_enabled;
 288
 289         if (state != 0 && state != 1)
 290                 return -EINVAL;
 291
 292         if (sid) {
 293                 char *ctx = NULL;
 294                 u32 len;
 295                 int rc;
 296                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 297                         return rc;
 298                 else
 299                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 300                                 "audit_enabled=%d old=%d by auid=%u subj=%s",
 301                                 state, old, loginuid, ctx);
 302                 kfree(ctx);
 303         } else
 304                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 305                         "audit_enabled=%d old=%d by auid=%u",
 306                         state, old, loginuid);
 307         audit_enabled = state;
 308         return 0;
 309 }
 310
 311 static int audit_set_failure(int state, uid_t loginuid, u32 sid)
 312 {
 313         int old = audit_failure;
 314
 315         if (state != AUDIT_FAIL_SILENT
 316             && state != AUDIT_FAIL_PRINTK
 317             && state != AUDIT_FAIL_PANIC)
 318                 return -EINVAL;
 319
 320         if (sid) {
 321                 char *ctx = NULL;
 322                 u32 len;
 323                 int rc;
 324                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 325                         return rc;
 326                 else
 327                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 328                                 "audit_failure=%d old=%d by auid=%u subj=%s",
 329                                 state, old, loginuid, ctx);
 330                 kfree(ctx);
 331         } else
 332                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 333                         "audit_failure=%d old=%d by auid=%u",
 334                         state, old, loginuid);
 335         audit_failure = state;
 336         return 0;
 337 }
 338
 339 static int kauditd_thread(void *dummy)
 340 {
 341         struct sk_buff *skb;
 342
 343         while (!kthread_should_stop()) {
 344                 skb = skb_dequeue(&audit_skb_queue);
 345                 wake_up(&audit_backlog_wait);
 346                 if (skb) {
 347                         if (audit_pid) {
 348                                 int err = netlink_unicast(audit_sock, skb, audit_pid, 0);
 349                                 if (err < 0) {
 350                                         BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
 351                                         printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
 352                                         audit_pid = 0;
 353                                 }
 354                         } else {
 355                                 printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0));
 356                                 kfree_skb(skb);
 357                         }
 358                 } else {
 359                         DECLARE_WAITQUEUE(wait, current);
 360                         set_current_state(TASK_INTERRUPTIBLE);
 361                         add_wait_queue(&kauditd_wait, &wait);
 362
 363                         if (!skb_queue_len(&audit_skb_queue)) {
 364                                 try_to_freeze();
 365                                 schedule();
 366                         }
 367
 368                         __set_current_state(TASK_RUNNING);
 369                         remove_wait_queue(&kauditd_wait, &wait);
 370                 }
 371         }
 372         return 0;
 373 }
 374
 375 int audit_send_list(void *_dest)
 376 {
 377         struct audit_netlink_list *dest = _dest;
 378         int pid = dest->pid;
 379         struct sk_buff *skb;
 380
 381         /* wait for parent to finish and send an ACK */
 382         mutex_lock(&audit_cmd_mutex);
 383         mutex_unlock(&audit_cmd_mutex);
 384
 385         while ((skb = __skb_dequeue(&dest->q)) != NULL)
 386                 netlink_unicast(audit_sock, skb, pid, 0);
 387
 388         kfree(dest);
 389
 390         return 0;
 391 }
 392
 393 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
 394                                  int multi, void *payload, int size)
 395 {
 396         struct sk_buff  *skb;
 397         struct nlmsghdr *nlh;
 398         int             len = NLMSG_SPACE(size);
 399         void            *data;
 400         int             flags = multi ? NLM_F_MULTI : 0;
 401         int             t     = done  ? NLMSG_DONE  : type;
 402
 403         skb = alloc_skb(len, GFP_KERNEL);
 404         if (!skb)
 405                 return NULL;
 406
 407         nlh              = NLMSG_PUT(skb, pid, seq, t, size);
 408         nlh->nlmsg_flags = flags;
 409         data             = NLMSG_DATA(nlh);
 410         memcpy(data, payload, size);
 411         return skb;
 412
 413 nlmsg_failure:                  /* Used by NLMSG_PUT */
 414         if (skb)
 415                 kfree_skb(skb);
 416         return NULL;
 417 }
 418
 419 /**
 420  * audit_send_reply - send an audit reply message via netlink
 421  * @pid: process id to send reply to
 422  * @seq: sequence number
 423  * @type: audit message type
 424  * @done: done (last) flag
 425  * @multi: multi-part message flag
 426  * @payload: payload data
 427  * @size: payload size
 428  *
 429  * Allocates an skb, builds the netlink message, and sends it to the pid.
 430  * No failure notifications.
 431  */
 432 void audit_send_reply(int pid, int seq, int type, int done, int multi,
 433                       void *payload, int size)
 434 {
 435         struct sk_buff  *skb;
 436         skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
 437         if (!skb)
 438                 return;
 439         /* Ignore failure. It'll only happen if the sender goes away,
 440            because our timeout is set to infinite. */
 441         netlink_unicast(audit_sock, skb, pid, 0);
 442         return;
 443 }
 444
 445 /*
 446  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 447  * control messages.
 448  */
 449 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 450 {
 451         int err = 0;
 452
 453         switch (msg_type) {
 454         case AUDIT_GET:
 455         case AUDIT_LIST:
 456         case AUDIT_LIST_RULES:
 457         case AUDIT_SET:
 458         case AUDIT_ADD:
 459         case AUDIT_ADD_RULE:
 460         case AUDIT_DEL:
 461         case AUDIT_DEL_RULE:
 462         case AUDIT_SIGNAL_INFO:
 463                 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
 464                         err = -EPERM;
 465                 break;
 466         case AUDIT_USER:
 467         case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
 468         case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2:
 469                 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
 470                         err = -EPERM;
 471                 break;
 472         default:  /* bad msg */
 473                 err = -EINVAL;
 474         }
 475
 476         return err;
 477 }
 478
 479 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 480 {
 481         u32                     uid, pid, seq, sid;
 482         void                    *data;
 483         struct audit_status     *status_get, status_set;
 484         int                     err;
 485         struct audit_buffer     *ab;
 486         u16                     msg_type = nlh->nlmsg_type;
 487         uid_t                   loginuid; /* loginuid of sender */
 488         struct audit_sig_info   *sig_data;
 489         char                    *ctx;
 490         u32                     len;
 491
 492         err = audit_netlink_ok(skb, msg_type);
 493         if (err)
 494                 return err;
 495
 496         /* As soon as there's any sign of userspace auditd,
 497          * start kauditd to talk to it */
 498         if (!kauditd_task)
 499                 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 500         if (IS_ERR(kauditd_task)) {
 501                 err = PTR_ERR(kauditd_task);
 502                 kauditd_task = NULL;
 503                 return err;
 504         }
 505
 506         pid  = NETLINK_CREDS(skb)->pid;
 507         uid  = NETLINK_CREDS(skb)->uid;
 508         loginuid = NETLINK_CB(skb).loginuid;
 509         sid  = NETLINK_CB(skb).sid;
 510         seq  = nlh->nlmsg_seq;
 511         data = NLMSG_DATA(nlh);
 512
 513         switch (msg_type) {
 514         case AUDIT_GET:
 515                 status_set.enabled       = audit_enabled;
 516                 status_set.failure       = audit_failure;
 517                 status_set.pid           = audit_pid;
 518                 status_set.rate_limit    = audit_rate_limit;
 519                 status_set.backlog_limit = audit_backlog_limit;
 520                 status_set.lost          = atomic_read(&audit_lost);
 521                 status_set.backlog       = skb_queue_len(&audit_skb_queue);
 522                 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
 523                                  &status_set, sizeof(status_set));
 524                 break;
 525         case AUDIT_SET:
 526                 if (nlh->nlmsg_len < sizeof(struct audit_status))
 527                         return -EINVAL;
 528                 status_get   = (struct audit_status *)data;
 529                 if (status_get->mask & AUDIT_STATUS_ENABLED) {
 530                         err = audit_set_enabled(status_get->enabled,
 531                                                         loginuid, sid);
 532                         if (err < 0) return err;
 533                 }
 534                 if (status_get->mask & AUDIT_STATUS_FAILURE) {
 535                         err = audit_set_failure(status_get->failure,
 536                                                          loginuid, sid);
 537                         if (err < 0) return err;
 538                 }
 539                 if (status_get->mask & AUDIT_STATUS_PID) {
 540                         int old   = audit_pid;
 541                         if (sid) {
 542                                 if ((err = selinux_sid_to_string(
 543                                                 sid, &ctx, &len)))
 544                                         return err;
 545                                 else
 546                                         audit_log(NULL, GFP_KERNEL,
 547                                                 AUDIT_CONFIG_CHANGE,
 548                                                 "audit_pid=%d old=%d by auid=%u subj=%s",
 549                                                 status_get->pid, old,
 550                                                 loginuid, ctx);
 551                                 kfree(ctx);
 552                         } else
 553                                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 554                                         "audit_pid=%d old=%d by auid=%u",
 555                                           status_get->pid, old, loginuid);
 556                         audit_pid = status_get->pid;
 557                 }
 558                 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
 559                         err = audit_set_rate_limit(status_get->rate_limit,
 560                                                          loginuid, sid);
 561                 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
 562                         err = audit_set_backlog_limit(status_get->backlog_limit,
 563                                                         loginuid, sid);
 564                 break;
 565         case AUDIT_USER:
 566         case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
 567         case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2:
 568                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 569                         return 0;
 570
 571                 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
 572                 if (err == 1) {
 573                         err = 0;
 574                         ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 575                         if (ab) {
 576                                 audit_log_format(ab,
 577                                                  "user pid=%d uid=%u auid=%u",
 578                                                  pid, uid, loginuid);
 579                                 if (sid) {
 580                                         if (selinux_sid_to_string(
 581                                                         sid, &ctx, &len)) {
 582                                                 audit_log_format(ab,
 583                                                         " ssid=%u", sid);
 584                                                 /* Maybe call audit_panic? */
 585                                         } else
 586                                                 audit_log_format(ab,
 587                                                         " subj=%s", ctx);
 588                                         kfree(ctx);
 589                                 }
 590                                 audit_log_format(ab, " msg='%.1024s'",
 591                                          (char *)data);
 592                                 audit_set_pid(ab, pid);
 593                                 audit_log_end(ab);
 594                         }
 595                 }
 596                 break;
 597         case AUDIT_ADD:
 598         case AUDIT_DEL:
 599                 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 600                         return -EINVAL;
 601                 /* fallthrough */
 602         case AUDIT_LIST:
 603                 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
 604                                            uid, seq, data, nlmsg_len(nlh),
 605                                            loginuid, sid);
 606                 break;
 607         case AUDIT_ADD_RULE:
 608         case AUDIT_DEL_RULE:
 609                 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 610                         return -EINVAL;
 611                 /* fallthrough */
 612         case AUDIT_LIST_RULES:
 613                 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
 614                                            uid, seq, data, nlmsg_len(nlh),
 615                                            loginuid, sid);
 616                 break;
 617         case AUDIT_SIGNAL_INFO:
 618                 err = selinux_sid_to_string(audit_sig_sid, &ctx, &len);
 619                 if (err)
 620                         return err;
 621                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 622                 if (!sig_data) {
 623                         kfree(ctx);
 624                         return -ENOMEM;
 625                 }
 626                 sig_data->uid = audit_sig_uid;
 627                 sig_data->pid = audit_sig_pid;
 628                 memcpy(sig_data->ctx, ctx, len);
 629                 kfree(ctx);
 630                 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
 631                                 0, 0, sig_data, sizeof(*sig_data) + len);
 632                 kfree(sig_data);
 633                 break;
 634         default:
 635                 err = -EINVAL;
 636                 break;
 637         }
 638
 639         return err < 0 ? err : 0;
 640 }
 641
 642 /*
 643  * Get message from skb (based on rtnetlink_rcv_skb).  Each message is
 644  * processed by audit_receive_msg.  Malformed skbs with wrong length are
 645  * discarded silently.
 646  */
 647 static void audit_receive_skb(struct sk_buff *skb)
 648 {
 649         int             err;
 650         struct nlmsghdr *nlh;
 651         u32             rlen;
 652
 653         while (skb->len >= NLMSG_SPACE(0)) {
 654                 nlh = (struct nlmsghdr *)skb->data;
 655                 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 656                         return;
 657                 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
 658                 if (rlen > skb->len)
 659                         rlen = skb->len;
 660                 if ((err = audit_receive_msg(skb, nlh))) {
 661                         netlink_ack(skb, nlh, err);
 662                 } else if (nlh->nlmsg_flags & NLM_F_ACK)
 663                         netlink_ack(skb, nlh, 0);
 664                 skb_pull(skb, rlen);
 665         }
 666 }
 667
 668 /* Receive messages from netlink socket. */
 669 static void audit_receive(struct sock *sk, int length)
 670 {
 671         struct sk_buff  *skb;
 672         unsigned int qlen;
 673
 674         mutex_lock(&audit_cmd_mutex);
 675
 676         for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) {
 677                 skb = skb_dequeue(&sk->sk_receive_queue);
 678                 audit_receive_skb(skb);
 679                 kfree_skb(skb);
 680         }
 681         mutex_unlock(&audit_cmd_mutex);
 682 }
 683
 684 #ifdef CONFIG_AUDITSYSCALL
 685 static const struct inotify_operations audit_inotify_ops = {
 686         .handle_event   = audit_handle_ievent,
 687         .destroy_watch  = audit_free_parent,
 688 };
 689 #endif
 690
 691 /* Initialize audit support at boot time. */
 692 static int __init audit_init(void)
 693 {
 694         int i;
 695
 696         printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
 697                audit_default ? "enabled" : "disabled");
 698         audit_sock = netlink_kernel_create(NETLINK_AUDIT, 0, audit_receive,
 699                                            THIS_MODULE);
 700         if (!audit_sock)
 701                 audit_panic("cannot initialize netlink socket");
 702         else
 703                 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
 704
 705         skb_queue_head_init(&audit_skb_queue);
 706         audit_initialized = 1;
 707         audit_enabled = audit_default;
 708
 709         /* Register the callback with selinux.  This callback will be invoked
 710          * when a new policy is loaded. */
 711         selinux_audit_set_callback(&selinux_audit_rule_update);
 712
 713         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
 714
 715 #ifdef CONFIG_AUDITSYSCALL
 716         audit_ih = inotify_init(&audit_inotify_ops);
 717         if (IS_ERR(audit_ih))
 718                 audit_panic("cannot initialize inotify handle");
 719 #endif
 720
 721         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
 722                 INIT_LIST_HEAD(&audit_inode_hash[i]);
 723
 724         return 0;
 725 }
 726 __initcall(audit_init);
 727
 728 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
 729 static int __init audit_enable(char *str)
 730 {
 731         audit_default = !!simple_strtol(str, NULL, 0);
 732         printk(KERN_INFO "audit: %s%s\n",
 733                audit_default ? "enabled" : "disabled",
 734                audit_initialized ? "" : " (after initialization)");
 735         if (audit_initialized)
 736                 audit_enabled = audit_default;
 737         return 1;
 738 }
 739
 740 __setup("audit=", audit_enable);
 741
 742 static void audit_buffer_free(struct audit_buffer *ab)
 743 {
 744         unsigned long flags;
 745
 746         if (!ab)
 747                 return;
 748
 749         if (ab->skb)
 750                 kfree_skb(ab->skb);
 751
 752         spin_lock_irqsave(&audit_freelist_lock, flags);
 753         if (audit_freelist_count > AUDIT_MAXFREE)
 754                 kfree(ab);
 755         else {
 756                 audit_freelist_count++;
 757                 list_add(&ab->list, &audit_freelist);
 758         }
 759         spin_unlock_irqrestore(&audit_freelist_lock, flags);
 760 }
 761
 762 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
 763                                                 gfp_t gfp_mask, int type)
 764 {
 765         unsigned long flags;
 766         struct audit_buffer *ab = NULL;
 767         struct nlmsghdr *nlh;
 768
 769         spin_lock_irqsave(&audit_freelist_lock, flags);
 770         if (!list_empty(&audit_freelist)) {
 771                 ab = list_entry(audit_freelist.next,
 772                                 struct audit_buffer, list);
 773                 list_del(&ab->list);
 774                 --audit_freelist_count;
 775         }
 776         spin_unlock_irqrestore(&audit_freelist_lock, flags);
 777
 778         if (!ab) {
 779                 ab = kmalloc(sizeof(*ab), gfp_mask);
 780                 if (!ab)
 781                         goto err;
 782         }
 783
 784         ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
 785         if (!ab->skb)
 786                 goto err;
 787
 788         ab->ctx = ctx;
 789         ab->gfp_mask = gfp_mask;
 790         nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
 791         nlh->nlmsg_type = type;
 792         nlh->nlmsg_flags = 0;
 793         nlh->nlmsg_pid = 0;
 794         nlh->nlmsg_seq = 0;
 795         return ab;
 796 err:
 797         audit_buffer_free(ab);
 798         return NULL;
 799 }
 800
 801 /**
 802  * audit_serial - compute a serial number for the audit record
 803  *
 804  * Compute a serial number for the audit record.  Audit records are
 805  * written to user-space as soon as they are generated, so a complete
 806  * audit record may be written in several pieces.  The timestamp of the
 807  * record and this serial number are used by the user-space tools to
 808  * determine which pieces belong to the same audit record.  The
 809  * (timestamp,serial) tuple is unique for each syscall and is live from
 810  * syscall entry to syscall exit.
 811  *
 812  * NOTE: Another possibility is to store the formatted records off the
 813  * audit context (for those records that have a context), and emit them
 814  * all at syscall exit.  However, this could delay the reporting of
 815  * significant errors until syscall exit (or never, if the system
 816  * halts).
 817  */
 818 unsigned int audit_serial(void)
 819 {
 820         static DEFINE_SPINLOCK(serial_lock);
 821         static unsigned int serial = 0;
 822
 823         unsigned long flags;
 824         unsigned int ret;
 825
 826         spin_lock_irqsave(&serial_lock, flags);
 827         do {
 828                 ret = ++serial;
 829         } while (unlikely(!ret));
 830         spin_unlock_irqrestore(&serial_lock, flags);
 831
 832         return ret;
 833 }
 834
 835 static inline void audit_get_stamp(struct audit_context *ctx,
 836                                    struct timespec *t, unsigned int *serial)
 837 {
 838         if (ctx)
 839                 auditsc_get_stamp(ctx, t, serial);
 840         else {
 841                 *t = CURRENT_TIME;
 842                 *serial = audit_serial();
 843         }
 844 }
 845
 846 /* Obtain an audit buffer.  This routine does locking to obtain the
 847  * audit buffer, but then no locking is required for calls to
 848  * audit_log_*format.  If the tsk is a task that is currently in a
 849  * syscall, then the syscall is marked as auditable and an audit record
 850  * will be written at syscall exit.  If there is no associated task, tsk
 851  * should be NULL. */
 852
 853 /**
 854  * audit_log_start - obtain an audit buffer
 855  * @ctx: audit_context (may be NULL)
 856  * @gfp_mask: type of allocation
 857  * @type: audit message type
 858  *
 859  * Returns audit_buffer pointer on success or NULL on error.
 860  *
 861  * Obtain an audit buffer.  This routine does locking to obtain the
 862  * audit buffer, but then no locking is required for calls to
 863  * audit_log_*format.  If the task (ctx) is a task that is currently in a
 864  * syscall, then the syscall is marked as auditable and an audit record
 865  * will be written at syscall exit.  If there is no associated task, then
 866  * task context (ctx) should be NULL.
 867  */
 868 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 869                                      int type)
 870 {
 871         struct audit_buffer     *ab     = NULL;
 872         struct timespec         t;
 873         unsigned int            serial;
 874         int reserve;
 875         unsigned long timeout_start = jiffies;
 876
 877         if (!audit_initialized)
 878                 return NULL;
 879
 880         if (unlikely(audit_filter_type(type)))
 881                 return NULL;
 882
 883         if (gfp_mask & __GFP_WAIT)
 884                 reserve = 0;
 885         else
 886                 reserve = 5; /* Allow atomic callers to go up to five
 887                                 entries over the normal backlog limit */
 888
 889         while (audit_backlog_limit
 890                && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
 891                 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
 892                     && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
 893
 894                         /* Wait for auditd to drain the queue a little */
 895                         DECLARE_WAITQUEUE(wait, current);
 896                         set_current_state(TASK_INTERRUPTIBLE);
 897                         add_wait_queue(&audit_backlog_wait, &wait);
 898
 899                         if (audit_backlog_limit &&
 900                             skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
 901                                 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
 902
 903                         __set_current_state(TASK_RUNNING);
 904                         remove_wait_queue(&audit_backlog_wait, &wait);
 905                         continue;
 906                 }
 907                 if (audit_rate_check())
 908                         printk(KERN_WARNING
 909                                "audit: audit_backlog=%d > "
 910                                "audit_backlog_limit=%d\n",
 911                                skb_queue_len(&audit_skb_queue),
 912                                audit_backlog_limit);
 913                 audit_log_lost("backlog limit exceeded");
 914                 audit_backlog_wait_time = audit_backlog_wait_overflow;
 915                 wake_up(&audit_backlog_wait);
 916                 return NULL;
 917         }
 918
 919         ab = audit_buffer_alloc(ctx, gfp_mask, type);
 920         if (!ab) {
 921                 audit_log_lost("out of memory in audit_log_start");
 922                 return NULL;
 923         }
 924
 925         audit_get_stamp(ab->ctx, &t, &serial);
 926
 927         audit_log_format(ab, "audit(%lu.%03lu:%u): ",
 928                          t.tv_sec, t.tv_nsec/1000000, serial);
 929         return ab;
 930 }
 931
 932 /**
 933  * audit_expand - expand skb in the audit buffer
 934  * @ab: audit_buffer
 935  * @extra: space to add at tail of the skb
 936  *
 937  * Returns 0 (no space) on failed expansion, or available space if
 938  * successful.
 939  */
 940 static inline int audit_expand(struct audit_buffer *ab, int extra)
 941 {
 942         struct sk_buff *skb = ab->skb;
 943         int ret = pskb_expand_head(skb, skb_headroom(skb), extra,
 944                                    ab->gfp_mask);
 945         if (ret < 0) {
 946                 audit_log_lost("out of memory in audit_expand");
 947                 return 0;
 948         }
 949         return skb_tailroom(skb);
 950 }
 951
 952 /*
 953  * Format an audit message into the audit buffer.  If there isn't enough
 954  * room in the audit buffer, more room will be allocated and vsnprint
 955  * will be called a second time.  Currently, we assume that a printk
 956  * can't format message larger than 1024 bytes, so we don't either.
 957  */
 958 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
 959                               va_list args)
 960 {
 961         int len, avail;
 962         struct sk_buff *skb;
 963         va_list args2;
 964
 965         if (!ab)
 966                 return;
 967
 968         BUG_ON(!ab->skb);
 969         skb = ab->skb;
 970         avail = skb_tailroom(skb);
 971         if (avail == 0) {
 972                 avail = audit_expand(ab, AUDIT_BUFSIZ);
 973                 if (!avail)
 974                         goto out;
 975         }
 976         va_copy(args2, args);
 977         len = vsnprintf(skb->tail, avail, fmt, args);
 978         if (len >= avail) {
 979                 /* The printk buffer is 1024 bytes long, so if we get
 980                  * here and AUDIT_BUFSIZ is at least 1024, then we can
 981                  * log everything that printk could have logged. */
 982                 avail = audit_expand(ab,
 983                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
 984                 if (!avail)
 985                         goto out;
 986                 len = vsnprintf(skb->tail, avail, fmt, args2);
 987         }
 988         if (len > 0)
 989                 skb_put(skb, len);
 990 out:
 991         return;
 992 }
 993
 994 /**
 995  * audit_log_format - format a message into the audit buffer.
 996  * @ab: audit_buffer
 997  * @fmt: format string
 998  * @...: optional parameters matching @fmt string
 999  *
1000  * All the work is done in audit_log_vformat.
1001  */
1002 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1003 {
1004         va_list args;
1005
1006         if (!ab)
1007                 return;
1008         va_start(args, fmt);
1009         audit_log_vformat(ab, fmt, args);
1010         va_end(args);
1011 }
1012
1013 /**
1014  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1015  * @ab: the audit_buffer
1016  * @buf: buffer to convert to hex
1017  * @len: length of @buf to be converted
1018  *
1019  * No return value; failure to expand is silently ignored.
1020  *
1021  * This function will take the passed buf and convert it into a string of
1022  * ascii hex digits. The new string is placed onto the skb.
1023  */
1024 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1025                 size_t len)
1026 {
1027         int i, avail, new_len;
1028         unsigned char *ptr;
1029         struct sk_buff *skb;
1030         static const unsigned char *hex = "0123456789ABCDEF";
1031
1032         if (!ab)
1033                 return;
1034
1035         BUG_ON(!ab->skb);
1036         skb = ab->skb;
1037         avail = skb_tailroom(skb);
1038         new_len = len<<1;
1039         if (new_len >= avail) {
1040                 /* Round the buffer request up to the next multiple */
1041                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1042                 avail = audit_expand(ab, new_len);
1043                 if (!avail)
1044                         return;
1045         }
1046
1047         ptr = skb->tail;
1048         for (i=0; i<len; i++) {
1049                 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1050                 *ptr++ = hex[buf[i] & 0x0F];      /* Lower nibble */
1051         }
1052         *ptr = 0;
1053         skb_put(skb, len << 1); /* new string is twice the old string */
1054 }
1055
1056 /*
1057  * Format a string of no more than slen characters into the audit buffer,
1058  * enclosed in quote marks.
1059  */
1060 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1061                                const char *string)
1062 {
1063         int avail, new_len;
1064         unsigned char *ptr;
1065         struct sk_buff *skb;
1066
1067         if (!ab)
1068                 return;
1069
1070         BUG_ON(!ab->skb);
1071         skb = ab->skb;
1072         avail = skb_tailroom(skb);
1073         new_len = slen + 3;     /* enclosing quotes + null terminator */
1074         if (new_len > avail) {
1075                 avail = audit_expand(ab, new_len);
1076                 if (!avail)
1077                         return;
1078         }
1079         ptr = skb->tail;
1080         *ptr++ = '"';
1081         memcpy(ptr, string, slen);
1082         ptr += slen;
1083         *ptr++ = '"';
1084         *ptr = 0;
1085         skb_put(skb, slen + 2); /* don't include null terminator */
1086 }
1087
1088 /**
1089  * audit_log_n_unstrustedstring - log a string that may contain random characters
1090  * @ab: audit_buffer
1091  * @len: lenth of string (not including trailing null)
1092  * @string: string to be logged
1093  *
1094  * This code will escape a string that is passed to it if the string
1095  * contains a control character, unprintable character, double quote mark,
1096  * or a space. Unescaped strings will start and end with a double quote mark.
1097  * Strings that are escaped are printed in hex (2 digits per char).
1098  *
1099  * The caller specifies the number of characters in the string to log, which may
1100  * or may not be the entire string.
1101  */
1102 const char *audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1103                                         const char *string)
1104 {
1105         const unsigned char *p = string;
1106
1107         while (*p) {
1108                 if (*p == '"' || *p < 0x21 || *p > 0x7f) {
1109                         audit_log_hex(ab, string, len);
1110                         return string + len + 1;
1111                 }
1112                 p++;
1113         }
1114         audit_log_n_string(ab, len, string);
1115         return p + 1;
1116 }
1117
1118 /**
1119  * audit_log_unstrustedstring - log a string that may contain random characters
1120  * @ab: audit_buffer
1121  * @string: string to be logged
1122  *
1123  * Same as audit_log_n_unstrustedstring(), except that strlen is used to
1124  * determine string length.
1125  */
1126 const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1127 {
1128         return audit_log_n_untrustedstring(ab, strlen(string), string);
1129 }
1130
1131 /* This is a helper-function to print the escaped d_path */
1132 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1133                       struct dentry *dentry, struct vfsmount *vfsmnt)
1134 {
1135         char *p, *path;
1136
1137         if (prefix)
1138                 audit_log_format(ab, " %s", prefix);
1139
1140         /* We will allow 11 spaces for ' (deleted)' to be appended */
1141         path = kmalloc(PATH_MAX+11, ab->gfp_mask);
1142         if (!path) {
1143                 audit_log_format(ab, "<no memory>");
1144                 return;
1145         }
1146         p = d_path(dentry, vfsmnt, path, PATH_MAX+11);
1147         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1148                 /* FIXME: can we save some information here? */
1149                 audit_log_format(ab, "<too long>");
1150         } else
1151                 audit_log_untrustedstring(ab, p);
1152         kfree(path);
1153 }
1154
1155 /**
1156  * audit_log_end - end one audit record
1157  * @ab: the audit_buffer
1158  *
1159  * The netlink_* functions cannot be called inside an irq context, so
1160  * the audit buffer is placed on a queue and a tasklet is scheduled to
1161  * remove them from the queue outside the irq context.  May be called in
1162  * any context.
1163  */
1164 void audit_log_end(struct audit_buffer *ab)
1165 {
1166         if (!ab)
1167                 return;
1168         if (!audit_rate_check()) {
1169                 audit_log_lost("rate limit exceeded");
1170         } else {
1171                 if (audit_pid) {
1172                         struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
1173                         nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1174                         skb_queue_tail(&audit_skb_queue, ab->skb);
1175                         ab->skb = NULL;
1176                         wake_up_interruptible(&kauditd_wait);
1177                 } else {
1178                         printk(KERN_NOTICE "%s\n", ab->skb->data + NLMSG_SPACE(0));
1179                 }
1180         }
1181         audit_buffer_free(ab);
1182 }
1183
1184 /**
1185  * audit_log - Log an audit record
1186  * @ctx: audit context
1187  * @gfp_mask: type of allocation
1188  * @type: audit message type
1189  * @fmt: format string to use
1190  * @...: variable parameters matching the format string
1191  *
1192  * This is a convenience function that calls audit_log_start,
1193  * audit_log_vformat, and audit_log_end.  It may be called
1194  * in any context.
1195  */
1196 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1197                const char *fmt, ...)
1198 {
1199         struct audit_buffer *ab;
1200         va_list args;
1201
1202         ab = audit_log_start(ctx, gfp_mask, type);
1203         if (ab) {
1204                 va_start(args, fmt);
1205                 audit_log_vformat(ab, fmt, args);
1206                 va_end(args);
1207                 audit_log_end(ab);
1208         }
1209 }
1210
1211 EXPORT_SYMBOL(audit_log_start);
1212 EXPORT_SYMBOL(audit_log_end);
1213 EXPORT_SYMBOL(audit_log_format);
1214 EXPORT_SYMBOL(audit_log);