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_ctxid_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_ctxid_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_ctxid_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_ctxid_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 (1) {
 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 }
 373
 374 int audit_send_list(void *_dest)
 375 {
 376         struct audit_netlink_list *dest = _dest;
 377         int pid = dest->pid;
 378         struct sk_buff *skb;
 379
 380         /* wait for parent to finish and send an ACK */
 381         mutex_lock(&audit_cmd_mutex);
 382         mutex_unlock(&audit_cmd_mutex);
 383
 384         while ((skb = __skb_dequeue(&dest->q)) != NULL)
 385                 netlink_unicast(audit_sock, skb, pid, 0);
 386
 387         kfree(dest);
 388
 389         return 0;
 390 }
 391
 392 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
 393                                  int multi, void *payload, int size)
 394 {
 395         struct sk_buff  *skb;
 396         struct nlmsghdr *nlh;
 397         int             len = NLMSG_SPACE(size);
 398         void            *data;
 399         int             flags = multi ? NLM_F_MULTI : 0;
 400         int             t     = done  ? NLMSG_DONE  : type;
 401
 402         skb = alloc_skb(len, GFP_KERNEL);
 403         if (!skb)
 404                 return NULL;
 405
 406         nlh              = NLMSG_PUT(skb, pid, seq, t, size);
 407         nlh->nlmsg_flags = flags;
 408         data             = NLMSG_DATA(nlh);
 409         memcpy(data, payload, size);
 410         return skb;
 411
 412 nlmsg_failure:                  /* Used by NLMSG_PUT */
 413         if (skb)
 414                 kfree_skb(skb);
 415         return NULL;
 416 }
 417
 418 /**
 419  * audit_send_reply - send an audit reply message via netlink
 420  * @pid: process id to send reply to
 421  * @seq: sequence number
 422  * @type: audit message type
 423  * @done: done (last) flag
 424  * @multi: multi-part message flag
 425  * @payload: payload data
 426  * @size: payload size
 427  *
 428  * Allocates an skb, builds the netlink message, and sends it to the pid.
 429  * No failure notifications.
 430  */
 431 void audit_send_reply(int pid, int seq, int type, int done, int multi,
 432                       void *payload, int size)
 433 {
 434         struct sk_buff  *skb;
 435         skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
 436         if (!skb)
 437                 return;
 438         /* Ignore failure. It'll only happen if the sender goes away,
 439            because our timeout is set to infinite. */
 440         netlink_unicast(audit_sock, skb, pid, 0);
 441         return;
 442 }
 443
 444 /*
 445  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 446  * control messages.
 447  */
 448 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 449 {
 450         int err = 0;
 451
 452         switch (msg_type) {
 453         case AUDIT_GET:
 454         case AUDIT_LIST:
 455         case AUDIT_LIST_RULES:
 456         case AUDIT_SET:
 457         case AUDIT_ADD:
 458         case AUDIT_ADD_RULE:
 459         case AUDIT_DEL:
 460         case AUDIT_DEL_RULE:
 461         case AUDIT_SIGNAL_INFO:
 462                 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
 463                         err = -EPERM;
 464                 break;
 465         case AUDIT_USER:
 466         case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
 467         case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2:
 468                 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
 469                         err = -EPERM;
 470                 break;
 471         default:  /* bad msg */
 472                 err = -EINVAL;
 473         }
 474
 475         return err;
 476 }
 477
 478 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 479 {
 480         u32                     uid, pid, seq, sid;
 481         void                    *data;
 482         struct audit_status     *status_get, status_set;
 483         int                     err;
 484         struct audit_buffer     *ab;
 485         u16                     msg_type = nlh->nlmsg_type;
 486         uid_t                   loginuid; /* loginuid of sender */
 487         struct audit_sig_info   *sig_data;
 488         char                    *ctx;
 489         u32                     len;
 490
 491         err = audit_netlink_ok(skb, msg_type);
 492         if (err)
 493                 return err;
 494
 495         /* As soon as there's any sign of userspace auditd,
 496          * start kauditd to talk to it */
 497         if (!kauditd_task)
 498                 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 499         if (IS_ERR(kauditd_task)) {
 500                 err = PTR_ERR(kauditd_task);
 501                 kauditd_task = NULL;
 502                 return err;
 503         }
 504
 505         pid  = NETLINK_CREDS(skb)->pid;
 506         uid  = NETLINK_CREDS(skb)->uid;
 507         loginuid = NETLINK_CB(skb).loginuid;
 508         sid  = NETLINK_CB(skb).sid;
 509         seq  = nlh->nlmsg_seq;
 510         data = NLMSG_DATA(nlh);
 511
 512         switch (msg_type) {
 513         case AUDIT_GET:
 514                 status_set.enabled       = audit_enabled;
 515                 status_set.failure       = audit_failure;
 516                 status_set.pid           = audit_pid;
 517                 status_set.rate_limit    = audit_rate_limit;
 518                 status_set.backlog_limit = audit_backlog_limit;
 519                 status_set.lost          = atomic_read(&audit_lost);
 520                 status_set.backlog       = skb_queue_len(&audit_skb_queue);
 521                 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
 522                                  &status_set, sizeof(status_set));
 523                 break;
 524         case AUDIT_SET:
 525                 if (nlh->nlmsg_len < sizeof(struct audit_status))
 526                         return -EINVAL;
 527                 status_get   = (struct audit_status *)data;
 528                 if (status_get->mask & AUDIT_STATUS_ENABLED) {
 529                         err = audit_set_enabled(status_get->enabled,
 530                                                         loginuid, sid);
 531                         if (err < 0) return err;
 532                 }
 533                 if (status_get->mask & AUDIT_STATUS_FAILURE) {
 534                         err = audit_set_failure(status_get->failure,
 535                                                          loginuid, sid);
 536                         if (err < 0) return err;
 537                 }
 538                 if (status_get->mask & AUDIT_STATUS_PID) {
 539                         int old   = audit_pid;
 540                         if (sid) {
 541                                 if ((err = selinux_ctxid_to_string(
 542                                                 sid, &ctx, &len)))
 543                                         return err;
 544                                 else
 545                                         audit_log(NULL, GFP_KERNEL,
 546                                                 AUDIT_CONFIG_CHANGE,
 547                                                 "audit_pid=%d old=%d by auid=%u subj=%s",
 548                                                 status_get->pid, old,
 549                                                 loginuid, ctx);
 550                                 kfree(ctx);
 551                         } else
 552                                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 553                                         "audit_pid=%d old=%d by auid=%u",
 554                                           status_get->pid, old, loginuid);
 555                         audit_pid = status_get->pid;
 556                 }
 557                 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
 558                         err = audit_set_rate_limit(status_get->rate_limit,
 559                                                          loginuid, sid);
 560                 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
 561                         err = audit_set_backlog_limit(status_get->backlog_limit,
 562                                                         loginuid, sid);
 563                 break;
 564         case AUDIT_USER:
 565         case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
 566         case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2:
 567                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 568                         return 0;
 569
 570                 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
 571                 if (err == 1) {
 572                         err = 0;
 573                         ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 574                         if (ab) {
 575                                 audit_log_format(ab,
 576                                                  "user pid=%d uid=%u auid=%u",
 577                                                  pid, uid, loginuid);
 578                                 if (sid) {
 579                                         if (selinux_ctxid_to_string(
 580                                                         sid, &ctx, &len)) {
 581                                                 audit_log_format(ab,
 582                                                         " ssid=%u", sid);
 583                                                 /* Maybe call audit_panic? */
 584                                         } else
 585                                                 audit_log_format(ab,
 586                                                         " subj=%s", ctx);
 587                                         kfree(ctx);
 588                                 }
 589                                 audit_log_format(ab, " msg='%.1024s'",
 590                                          (char *)data);
 591                                 audit_set_pid(ab, pid);
 592                                 audit_log_end(ab);
 593                         }
 594                 }
 595                 break;
 596         case AUDIT_ADD:
 597         case AUDIT_DEL:
 598                 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 599                         return -EINVAL;
 600                 /* fallthrough */
 601         case AUDIT_LIST:
 602                 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
 603                                            uid, seq, data, nlmsg_len(nlh),
 604                                            loginuid, sid);
 605                 break;
 606         case AUDIT_ADD_RULE:
 607         case AUDIT_DEL_RULE:
 608                 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 609                         return -EINVAL;
 610                 /* fallthrough */
 611         case AUDIT_LIST_RULES:
 612                 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
 613                                            uid, seq, data, nlmsg_len(nlh),
 614                                            loginuid, sid);
 615                 break;
 616         case AUDIT_SIGNAL_INFO:
 617                 err = selinux_ctxid_to_string(audit_sig_sid, &ctx, &len);
 618                 if (err)
 619                         return err;
 620                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 621                 if (!sig_data) {
 622                         kfree(ctx);
 623                         return -ENOMEM;
 624                 }
 625                 sig_data->uid = audit_sig_uid;
 626                 sig_data->pid = audit_sig_pid;
 627                 memcpy(sig_data->ctx, ctx, len);
 628                 kfree(ctx);
 629                 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
 630                                 0, 0, sig_data, sizeof(*sig_data) + len);
 631                 kfree(sig_data);
 632                 break;
 633         default:
 634                 err = -EINVAL;
 635                 break;
 636         }
 637
 638         return err < 0 ? err : 0;
 639 }
 640
 641 /*
 642  * Get message from skb (based on rtnetlink_rcv_skb).  Each message is
 643  * processed by audit_receive_msg.  Malformed skbs with wrong length are
 644  * discarded silently.
 645  */
 646 static void audit_receive_skb(struct sk_buff *skb)
 647 {
 648         int             err;
 649         struct nlmsghdr *nlh;
 650         u32             rlen;
 651
 652         while (skb->len >= NLMSG_SPACE(0)) {
 653                 nlh = (struct nlmsghdr *)skb->data;
 654                 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 655                         return;
 656                 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
 657                 if (rlen > skb->len)
 658                         rlen = skb->len;
 659                 if ((err = audit_receive_msg(skb, nlh))) {
 660                         netlink_ack(skb, nlh, err);
 661                 } else if (nlh->nlmsg_flags & NLM_F_ACK)
 662                         netlink_ack(skb, nlh, 0);
 663                 skb_pull(skb, rlen);
 664         }
 665 }
 666
 667 /* Receive messages from netlink socket. */
 668 static void audit_receive(struct sock *sk, int length)
 669 {
 670         struct sk_buff  *skb;
 671         unsigned int qlen;
 672
 673         mutex_lock(&audit_cmd_mutex);
 674
 675         for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) {
 676                 skb = skb_dequeue(&sk->sk_receive_queue);
 677                 audit_receive_skb(skb);
 678                 kfree_skb(skb);
 679         }
 680         mutex_unlock(&audit_cmd_mutex);
 681 }
 682
 683 #ifdef CONFIG_AUDITSYSCALL
 684 static const struct inotify_operations audit_inotify_ops = {
 685         .handle_event   = audit_handle_ievent,
 686         .destroy_watch  = audit_free_parent,
 687 };
 688 #endif
 689
 690 /* Initialize audit support at boot time. */
 691 static int __init audit_init(void)
 692 {
 693         int i;
 694
 695         printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
 696                audit_default ? "enabled" : "disabled");
 697         audit_sock = netlink_kernel_create(NETLINK_AUDIT, 0, audit_receive,
 698                                            THIS_MODULE);
 699         if (!audit_sock)
 700                 audit_panic("cannot initialize netlink socket");
 701         else
 702                 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
 703
 704         skb_queue_head_init(&audit_skb_queue);
 705         audit_initialized = 1;
 706         audit_enabled = audit_default;
 707
 708         /* Register the callback with selinux.  This callback will be invoked
 709          * when a new policy is loaded. */
 710         selinux_audit_set_callback(&selinux_audit_rule_update);
 711
 712         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
 713
 714 #ifdef CONFIG_AUDITSYSCALL
 715         audit_ih = inotify_init(&audit_inotify_ops);
 716         if (IS_ERR(audit_ih))
 717                 audit_panic("cannot initialize inotify handle");
 718 #endif
 719
 720         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
 721                 INIT_LIST_HEAD(&audit_inode_hash[i]);
 722
 723         return 0;
 724 }
 725 __initcall(audit_init);
 726
 727 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
 728 static int __init audit_enable(char *str)
 729 {
 730         audit_default = !!simple_strtol(str, NULL, 0);
 731         printk(KERN_INFO "audit: %s%s\n",
 732                audit_default ? "enabled" : "disabled",
 733                audit_initialized ? "" : " (after initialization)");
 734         if (audit_initialized)
 735                 audit_enabled = audit_default;
 736         return 1;
 737 }
 738
 739 __setup("audit=", audit_enable);
 740
 741 static void audit_buffer_free(struct audit_buffer *ab)
 742 {
 743         unsigned long flags;
 744
 745         if (!ab)
 746                 return;
 747
 748         if (ab->skb)
 749                 kfree_skb(ab->skb);
 750
 751         spin_lock_irqsave(&audit_freelist_lock, flags);
 752         if (audit_freelist_count > AUDIT_MAXFREE)
 753                 kfree(ab);
 754         else {
 755                 audit_freelist_count++;
 756                 list_add(&ab->list, &audit_freelist);
 757         }
 758         spin_unlock_irqrestore(&audit_freelist_lock, flags);
 759 }
 760
 761 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
 762                                                 gfp_t gfp_mask, int type)
 763 {
 764         unsigned long flags;
 765         struct audit_buffer *ab = NULL;
 766         struct nlmsghdr *nlh;
 767
 768         spin_lock_irqsave(&audit_freelist_lock, flags);
 769         if (!list_empty(&audit_freelist)) {
 770                 ab = list_entry(audit_freelist.next,
 771                                 struct audit_buffer, list);
 772                 list_del(&ab->list);
 773                 --audit_freelist_count;
 774         }
 775         spin_unlock_irqrestore(&audit_freelist_lock, flags);
 776
 777         if (!ab) {
 778                 ab = kmalloc(sizeof(*ab), gfp_mask);
 779                 if (!ab)
 780                         goto err;
 781         }
 782
 783         ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
 784         if (!ab->skb)
 785                 goto err;
 786
 787         ab->ctx = ctx;
 788         ab->gfp_mask = gfp_mask;
 789         nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
 790         nlh->nlmsg_type = type;
 791         nlh->nlmsg_flags = 0;
 792         nlh->nlmsg_pid = 0;
 793         nlh->nlmsg_seq = 0;
 794         return ab;
 795 err:
 796         audit_buffer_free(ab);
 797         return NULL;
 798 }
 799
 800 /**
 801  * audit_serial - compute a serial number for the audit record
 802  *
 803  * Compute a serial number for the audit record.  Audit records are
 804  * written to user-space as soon as they are generated, so a complete
 805  * audit record may be written in several pieces.  The timestamp of the
 806  * record and this serial number are used by the user-space tools to
 807  * determine which pieces belong to the same audit record.  The
 808  * (timestamp,serial) tuple is unique for each syscall and is live from
 809  * syscall entry to syscall exit.
 810  *
 811  * NOTE: Another possibility is to store the formatted records off the
 812  * audit context (for those records that have a context), and emit them
 813  * all at syscall exit.  However, this could delay the reporting of
 814  * significant errors until syscall exit (or never, if the system
 815  * halts).
 816  */
 817 unsigned int audit_serial(void)
 818 {
 819         static DEFINE_SPINLOCK(serial_lock);
 820         static unsigned int serial = 0;
 821
 822         unsigned long flags;
 823         unsigned int ret;
 824
 825         spin_lock_irqsave(&serial_lock, flags);
 826         do {
 827                 ret = ++serial;
 828         } while (unlikely(!ret));
 829         spin_unlock_irqrestore(&serial_lock, flags);
 830
 831         return ret;
 832 }
 833
 834 static inline void audit_get_stamp(struct audit_context *ctx,
 835                                    struct timespec *t, unsigned int *serial)
 836 {
 837         if (ctx)
 838                 auditsc_get_stamp(ctx, t, serial);
 839         else {
 840                 *t = CURRENT_TIME;
 841                 *serial = audit_serial();
 842         }
 843 }
 844
 845 /* Obtain an audit buffer.  This routine does locking to obtain the
 846  * audit buffer, but then no locking is required for calls to
 847  * audit_log_*format.  If the tsk is a task that is currently in a
 848  * syscall, then the syscall is marked as auditable and an audit record
 849  * will be written at syscall exit.  If there is no associated task, tsk
 850  * should be NULL. */
 851
 852 /**
 853  * audit_log_start - obtain an audit buffer
 854  * @ctx: audit_context (may be NULL)
 855  * @gfp_mask: type of allocation
 856  * @type: audit message type
 857  *
 858  * Returns audit_buffer pointer on success or NULL on error.
 859  *
 860  * Obtain an audit buffer.  This routine does locking to obtain the
 861  * audit buffer, but then no locking is required for calls to
 862  * audit_log_*format.  If the task (ctx) is a task that is currently in a
 863  * syscall, then the syscall is marked as auditable and an audit record
 864  * will be written at syscall exit.  If there is no associated task, then
 865  * task context (ctx) should be NULL.
 866  */
 867 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 868                                      int type)
 869 {
 870         struct audit_buffer     *ab     = NULL;
 871         struct timespec         t;
 872         unsigned int            serial;
 873         int reserve;
 874         unsigned long timeout_start = jiffies;
 875
 876         if (!audit_initialized)
 877                 return NULL;
 878
 879         if (unlikely(audit_filter_type(type)))
 880                 return NULL;
 881
 882         if (gfp_mask & __GFP_WAIT)
 883                 reserve = 0;
 884         else
 885                 reserve = 5; /* Allow atomic callers to go up to five
 886                                 entries over the normal backlog limit */
 887
 888         while (audit_backlog_limit
 889                && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
 890                 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
 891                     && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
 892
 893                         /* Wait for auditd to drain the queue a little */
 894                         DECLARE_WAITQUEUE(wait, current);
 895                         set_current_state(TASK_INTERRUPTIBLE);
 896                         add_wait_queue(&audit_backlog_wait, &wait);
 897
 898                         if (audit_backlog_limit &&
 899                             skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
 900                                 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
 901
 902                         __set_current_state(TASK_RUNNING);
 903                         remove_wait_queue(&audit_backlog_wait, &wait);
 904                         continue;
 905                 }
 906                 if (audit_rate_check())
 907                         printk(KERN_WARNING
 908                                "audit: audit_backlog=%d > "
 909                                "audit_backlog_limit=%d\n",
 910                                skb_queue_len(&audit_skb_queue),
 911                                audit_backlog_limit);
 912                 audit_log_lost("backlog limit exceeded");
 913                 audit_backlog_wait_time = audit_backlog_wait_overflow;
 914                 wake_up(&audit_backlog_wait);
 915                 return NULL;
 916         }
 917
 918         ab = audit_buffer_alloc(ctx, gfp_mask, type);
 919         if (!ab) {
 920                 audit_log_lost("out of memory in audit_log_start");
 921                 return NULL;
 922         }
 923
 924         audit_get_stamp(ab->ctx, &t, &serial);
 925
 926         audit_log_format(ab, "audit(%lu.%03lu:%u): ",
 927                          t.tv_sec, t.tv_nsec/1000000, serial);
 928         return ab;
 929 }
 930
 931 /**
 932  * audit_expand - expand skb in the audit buffer
 933  * @ab: audit_buffer
 934  * @extra: space to add at tail of the skb
 935  *
 936  * Returns 0 (no space) on failed expansion, or available space if
 937  * successful.
 938  */
 939 static inline int audit_expand(struct audit_buffer *ab, int extra)
 940 {
 941         struct sk_buff *skb = ab->skb;
 942         int ret = pskb_expand_head(skb, skb_headroom(skb), extra,
 943                                    ab->gfp_mask);
 944         if (ret < 0) {
 945                 audit_log_lost("out of memory in audit_expand");
 946                 return 0;
 947         }
 948         return skb_tailroom(skb);
 949 }
 950
 951 /*
 952  * Format an audit message into the audit buffer.  If there isn't enough
 953  * room in the audit buffer, more room will be allocated and vsnprint
 954  * will be called a second time.  Currently, we assume that a printk
 955  * can't format message larger than 1024 bytes, so we don't either.
 956  */
 957 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
 958                               va_list args)
 959 {
 960         int len, avail;
 961         struct sk_buff *skb;
 962         va_list args2;
 963
 964         if (!ab)
 965                 return;
 966
 967         BUG_ON(!ab->skb);
 968         skb = ab->skb;
 969         avail = skb_tailroom(skb);
 970         if (avail == 0) {
 971                 avail = audit_expand(ab, AUDIT_BUFSIZ);
 972                 if (!avail)
 973                         goto out;
 974         }
 975         va_copy(args2, args);
 976         len = vsnprintf(skb->tail, avail, fmt, args);
 977         if (len >= avail) {
 978                 /* The printk buffer is 1024 bytes long, so if we get
 979                  * here and AUDIT_BUFSIZ is at least 1024, then we can
 980                  * log everything that printk could have logged. */
 981                 avail = audit_expand(ab,
 982                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
 983                 if (!avail)
 984                         goto out;
 985                 len = vsnprintf(skb->tail, avail, fmt, args2);
 986         }
 987         if (len > 0)
 988                 skb_put(skb, len);
 989 out:
 990         return;
 991 }
 992
 993 /**
 994  * audit_log_format - format a message into the audit buffer.
 995  * @ab: audit_buffer
 996  * @fmt: format string
 997  * @...: optional parameters matching @fmt string
 998  *
 999  * All the work is done in audit_log_vformat.
1000  */
1001 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1002 {
1003         va_list args;
1004
1005         if (!ab)
1006                 return;
1007         va_start(args, fmt);
1008         audit_log_vformat(ab, fmt, args);
1009         va_end(args);
1010 }
1011
1012 /**
1013  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1014  * @ab: the audit_buffer
1015  * @buf: buffer to convert to hex
1016  * @len: length of @buf to be converted
1017  *
1018  * No return value; failure to expand is silently ignored.
1019  *
1020  * This function will take the passed buf and convert it into a string of
1021  * ascii hex digits. The new string is placed onto the skb.
1022  */
1023 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1024                 size_t len)
1025 {
1026         int i, avail, new_len;
1027         unsigned char *ptr;
1028         struct sk_buff *skb;
1029         static const unsigned char *hex = "0123456789ABCDEF";
1030
1031         if (!ab)
1032                 return;
1033
1034         BUG_ON(!ab->skb);
1035         skb = ab->skb;
1036         avail = skb_tailroom(skb);
1037         new_len = len<<1;
1038         if (new_len >= avail) {
1039                 /* Round the buffer request up to the next multiple */
1040                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1041                 avail = audit_expand(ab, new_len);
1042                 if (!avail)
1043                         return;
1044         }
1045
1046         ptr = skb->tail;
1047         for (i=0; i<len; i++) {
1048                 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1049                 *ptr++ = hex[buf[i] & 0x0F];      /* Lower nibble */
1050         }
1051         *ptr = 0;
1052         skb_put(skb, len << 1); /* new string is twice the old string */
1053 }
1054
1055 /*
1056  * Format a string of no more than slen characters into the audit buffer,
1057  * enclosed in quote marks.
1058  */
1059 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1060                                const char *string)
1061 {
1062         int avail, new_len;
1063         unsigned char *ptr;
1064         struct sk_buff *skb;
1065
1066         if (!ab)
1067                 return;
1068
1069         BUG_ON(!ab->skb);
1070         skb = ab->skb;
1071         avail = skb_tailroom(skb);
1072         new_len = slen + 3;     /* enclosing quotes + null terminator */
1073         if (new_len > avail) {
1074                 avail = audit_expand(ab, new_len);
1075                 if (!avail)
1076                         return;
1077         }
1078         ptr = skb->tail;
1079         *ptr++ = '"';
1080         memcpy(ptr, string, slen);
1081         ptr += slen;
1082         *ptr++ = '"';
1083         *ptr = 0;
1084         skb_put(skb, slen + 2); /* don't include null terminator */
1085 }
1086
1087 /**
1088  * audit_log_n_unstrustedstring - log a string that may contain random characters
1089  * @ab: audit_buffer
1090  * @len: lenth of string (not including trailing null)
1091  * @string: string to be logged
1092  *
1093  * This code will escape a string that is passed to it if the string
1094  * contains a control character, unprintable character, double quote mark,
1095  * or a space. Unescaped strings will start and end with a double quote mark.
1096  * Strings that are escaped are printed in hex (2 digits per char).
1097  *
1098  * The caller specifies the number of characters in the string to log, which may
1099  * or may not be the entire string.
1100  */
1101 const char *audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1102                                         const char *string)
1103 {
1104         const unsigned char *p = string;
1105
1106         while (*p) {
1107                 if (*p == '"' || *p < 0x21 || *p > 0x7f) {
1108                         audit_log_hex(ab, string, len);
1109                         return string + len + 1;
1110                 }
1111                 p++;
1112         }
1113         audit_log_n_string(ab, len, string);
1114         return p + 1;
1115 }
1116
1117 /**
1118  * audit_log_unstrustedstring - log a string that may contain random characters
1119  * @ab: audit_buffer
1120  * @string: string to be logged
1121  *
1122  * Same as audit_log_n_unstrustedstring(), except that strlen is used to
1123  * determine string length.
1124  */
1125 const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1126 {
1127         return audit_log_n_untrustedstring(ab, strlen(string), string);
1128 }
1129
1130 /* This is a helper-function to print the escaped d_path */
1131 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1132                       struct dentry *dentry, struct vfsmount *vfsmnt)
1133 {
1134         char *p, *path;
1135
1136         if (prefix)
1137                 audit_log_format(ab, " %s", prefix);
1138
1139         /* We will allow 11 spaces for ' (deleted)' to be appended */
1140         path = kmalloc(PATH_MAX+11, ab->gfp_mask);
1141         if (!path) {
1142                 audit_log_format(ab, "<no memory>");
1143                 return;
1144         }
1145         p = d_path(dentry, vfsmnt, path, PATH_MAX+11);
1146         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1147                 /* FIXME: can we save some information here? */
1148                 audit_log_format(ab, "<too long>");
1149         } else
1150                 audit_log_untrustedstring(ab, p);
1151         kfree(path);
1152 }
1153
1154 /**
1155  * audit_log_end - end one audit record
1156  * @ab: the audit_buffer
1157  *
1158  * The netlink_* functions cannot be called inside an irq context, so
1159  * the audit buffer is placed on a queue and a tasklet is scheduled to
1160  * remove them from the queue outside the irq context.  May be called in
1161  * any context.
1162  */
1163 void audit_log_end(struct audit_buffer *ab)
1164 {
1165         if (!ab)
1166                 return;
1167         if (!audit_rate_check()) {
1168                 audit_log_lost("rate limit exceeded");
1169         } else {
1170                 if (audit_pid) {
1171                         struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
1172                         nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1173                         skb_queue_tail(&audit_skb_queue, ab->skb);
1174                         ab->skb = NULL;
1175                         wake_up_interruptible(&kauditd_wait);
1176                 } else {
1177                         printk(KERN_NOTICE "%s\n", ab->skb->data + NLMSG_SPACE(0));
1178                 }
1179         }
1180         audit_buffer_free(ab);
1181 }
1182
1183 /**
1184  * audit_log - Log an audit record
1185  * @ctx: audit context
1186  * @gfp_mask: type of allocation
1187  * @type: audit message type
1188  * @fmt: format string to use
1189  * @...: variable parameters matching the format string
1190  *
1191  * This is a convenience function that calls audit_log_start,
1192  * audit_log_vformat, and audit_log_end.  It may be called
1193  * in any context.
1194  */
1195 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1196                const char *fmt, ...)
1197 {
1198         struct audit_buffer *ab;
1199         va_list args;
1200
1201         ab = audit_log_start(ctx, gfp_mask, type);
1202         if (ab) {
1203                 va_start(args, fmt);
1204                 audit_log_vformat(ab, fmt, args);
1205                 va_end(args);
1206                 audit_log_end(ab);
1207         }
1208 }
1209
1210 EXPORT_SYMBOL(audit_log_start);
1211 EXPORT_SYMBOL(audit_log_end);
1212 EXPORT_SYMBOL(audit_log_format);
1213 EXPORT_SYMBOL(audit_log);