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 #include <linux/freezer.h>
  61
  62 #include "audit.h"
  63
  64 /* No auditing will take place until audit_initialized != 0.
  65  * (Initialization happens after skb_init is called.) */
  66 static int      audit_initialized;
  67
  68 /* No syscall auditing will take place unless audit_enabled != 0. */
  69 int             audit_enabled;
  70
  71 /* Default state when kernel boots without any parameters. */
  72 static int      audit_default;
  73
  74 /* If auditing cannot proceed, audit_failure selects what happens. */
  75 static int      audit_failure = AUDIT_FAIL_PRINTK;
  76
  77 /* If audit records are to be written to the netlink socket, audit_pid
  78  * contains the (non-zero) pid. */
  79 int             audit_pid;
  80
  81 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
  82  * to that number per second.  This prevents DoS attacks, but results in
  83  * audit records being dropped. */
  84 static int      audit_rate_limit;
  85
  86 /* Number of outstanding audit_buffers allowed. */
  87 static int      audit_backlog_limit = 64;
  88 static int      audit_backlog_wait_time = 60 * HZ;
  89 static int      audit_backlog_wait_overflow = 0;
  90
  91 /* The identity of the user shutting down the audit system. */
  92 uid_t           audit_sig_uid = -1;
  93 pid_t           audit_sig_pid = -1;
  94 u32             audit_sig_sid = 0;
  95
  96 /* Records can be lost in several ways:
  97    0) [suppressed in audit_alloc]
  98    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
  99    2) out of memory in audit_log_move [alloc_skb]
 100    3) suppressed due to audit_rate_limit
 101    4) suppressed due to audit_backlog_limit
 102 */
 103 static atomic_t    audit_lost = ATOMIC_INIT(0);
 104
 105 /* The netlink socket. */
 106 static struct sock *audit_sock;
 107
 108 /* Inotify handle. */
 109 struct inotify_handle *audit_ih;
 110
 111 /* Hash for inode-based rules */
 112 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 113
 114 /* The audit_freelist is a list of pre-allocated audit buffers (if more
 115  * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
 116  * being placed on the freelist). */
 117 static DEFINE_SPINLOCK(audit_freelist_lock);
 118 static int         audit_freelist_count;
 119 static LIST_HEAD(audit_freelist);
 120
 121 static struct sk_buff_head audit_skb_queue;
 122 static struct task_struct *kauditd_task;
 123 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 124 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 125
 126 /* Serialize requests from userspace. */
 127 static DEFINE_MUTEX(audit_cmd_mutex);
 128
 129 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 130  * audit records.  Since printk uses a 1024 byte buffer, this buffer
 131  * should be at least that large. */
 132 #define AUDIT_BUFSIZ 1024
 133
 134 /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
 135  * audit_freelist.  Doing so eliminates many kmalloc/kfree calls. */
 136 #define AUDIT_MAXFREE  (2*NR_CPUS)
 137
 138 /* The audit_buffer is used when formatting an audit record.  The caller
 139  * locks briefly to get the record off the freelist or to allocate the
 140  * buffer, and locks briefly to send the buffer to the netlink layer or
 141  * to place it on a transmit queue.  Multiple audit_buffers can be in
 142  * use simultaneously. */
 143 struct audit_buffer {
 144         struct list_head     list;
 145         struct sk_buff       *skb;      /* formatted skb ready to send */
 146         struct audit_context *ctx;      /* NULL or associated context */
 147         gfp_t                gfp_mask;
 148 };
 149
 150 static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
 151 {
 152         struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
 153         nlh->nlmsg_pid = pid;
 154 }
 155
 156 void audit_panic(const char *message)
 157 {
 158         switch (audit_failure)
 159         {
 160         case AUDIT_FAIL_SILENT:
 161                 break;
 162         case AUDIT_FAIL_PRINTK:
 163                 printk(KERN_ERR "audit: %s\n", message);
 164                 break;
 165         case AUDIT_FAIL_PANIC:
 166                 panic("audit: %s\n", message);
 167                 break;
 168         }
 169 }
 170
 171 static inline int audit_rate_check(void)
 172 {
 173         static unsigned long    last_check = 0;
 174         static int              messages   = 0;
 175         static DEFINE_SPINLOCK(lock);
 176         unsigned long           flags;
 177         unsigned long           now;
 178         unsigned long           elapsed;
 179         int                     retval     = 0;
 180
 181         if (!audit_rate_limit) return 1;
 182
 183         spin_lock_irqsave(&lock, flags);
 184         if (++messages < audit_rate_limit) {
 185                 retval = 1;
 186         } else {
 187                 now     = jiffies;
 188                 elapsed = now - last_check;
 189                 if (elapsed > HZ) {
 190                         last_check = now;
 191                         messages   = 0;
 192                         retval     = 1;
 193                 }
 194         }
 195         spin_unlock_irqrestore(&lock, flags);
 196
 197         return retval;
 198 }
 199
 200 /**
 201  * audit_log_lost - conditionally log lost audit message event
 202  * @message: the message stating reason for lost audit message
 203  *
 204  * Emit at least 1 message per second, even if audit_rate_check is
 205  * throttling.
 206  * Always increment the lost messages counter.
 207 */
 208 void audit_log_lost(const char *message)
 209 {
 210         static unsigned long    last_msg = 0;
 211         static DEFINE_SPINLOCK(lock);
 212         unsigned long           flags;
 213         unsigned long           now;
 214         int                     print;
 215
 216         atomic_inc(&audit_lost);
 217
 218         print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 219
 220         if (!print) {
 221                 spin_lock_irqsave(&lock, flags);
 222                 now = jiffies;
 223                 if (now - last_msg > HZ) {
 224                         print = 1;
 225                         last_msg = now;
 226                 }
 227                 spin_unlock_irqrestore(&lock, flags);
 228         }
 229
 230         if (print) {
 231                 printk(KERN_WARNING
 232                        "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n",
 233                        atomic_read(&audit_lost),
 234                        audit_rate_limit,
 235                        audit_backlog_limit);
 236                 audit_panic(message);
 237         }
 238 }
 239
 240 static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sid)
 241 {
 242         int old = audit_rate_limit;
 243
 244         if (sid) {
 245                 char *ctx = NULL;
 246                 u32 len;
 247                 int rc;
 248                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 249                         return rc;
 250                 else
 251                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 252                                 "audit_rate_limit=%d old=%d by auid=%u subj=%s",
 253                                 limit, old, loginuid, ctx);
 254                 kfree(ctx);
 255         } else
 256                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 257                         "audit_rate_limit=%d old=%d by auid=%u",
 258                         limit, old, loginuid);
 259         audit_rate_limit = limit;
 260         return 0;
 261 }
 262
 263 static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sid)
 264 {
 265         int old = audit_backlog_limit;
 266
 267         if (sid) {
 268                 char *ctx = NULL;
 269                 u32 len;
 270                 int rc;
 271                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 272                         return rc;
 273                 else
 274                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 275                             "audit_backlog_limit=%d old=%d by auid=%u subj=%s",
 276                                 limit, old, loginuid, ctx);
 277                 kfree(ctx);
 278         } else
 279                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 280                         "audit_backlog_limit=%d old=%d by auid=%u",
 281                         limit, old, loginuid);
 282         audit_backlog_limit = limit;
 283         return 0;
 284 }
 285
 286 static int audit_set_enabled(int state, uid_t loginuid, u32 sid)
 287 {
 288         int old = audit_enabled;
 289
 290         if (state != 0 && state != 1)
 291                 return -EINVAL;
 292
 293         if (sid) {
 294                 char *ctx = NULL;
 295                 u32 len;
 296                 int rc;
 297                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 298                         return rc;
 299                 else
 300                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 301                                 "audit_enabled=%d old=%d by auid=%u subj=%s",
 302                                 state, old, loginuid, ctx);
 303                 kfree(ctx);
 304         } else
 305                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 306                         "audit_enabled=%d old=%d by auid=%u",
 307                         state, old, loginuid);
 308         audit_enabled = state;
 309         return 0;
 310 }
 311
 312 static int audit_set_failure(int state, uid_t loginuid, u32 sid)
 313 {
 314         int old = audit_failure;
 315
 316         if (state != AUDIT_FAIL_SILENT
 317             && state != AUDIT_FAIL_PRINTK
 318             && state != AUDIT_FAIL_PANIC)
 319                 return -EINVAL;
 320
 321         if (sid) {
 322                 char *ctx = NULL;
 323                 u32 len;
 324                 int rc;
 325                 if ((rc = selinux_sid_to_string(sid, &ctx, &len)))
 326                         return rc;
 327                 else
 328                         audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 329                                 "audit_failure=%d old=%d by auid=%u subj=%s",
 330                                 state, old, loginuid, ctx);
 331                 kfree(ctx);
 332         } else
 333                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 334                         "audit_failure=%d old=%d by auid=%u",
 335                         state, old, loginuid);
 336         audit_failure = state;
 337         return 0;
 338 }
 339
 340 static int kauditd_thread(void *dummy)
 341 {
 342         struct sk_buff *skb;
 343
 344         while (!kthread_should_stop()) {
 345                 skb = skb_dequeue(&audit_skb_queue);
 346                 wake_up(&audit_backlog_wait);
 347                 if (skb) {
 348                         if (audit_pid) {
 349                                 int err = netlink_unicast(audit_sock, skb, audit_pid, 0);
 350                                 if (err < 0) {
 351                                         BUG_ON(err != -ECONNREFUSED); /* Shoudn't happen */
 352                                         printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
 353                                         audit_pid = 0;
 354                                 }
 355                         } else {
 356                                 printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0));
 357                                 kfree_skb(skb);
 358                         }
 359                 } else {
 360                         DECLARE_WAITQUEUE(wait, current);
 361                         set_current_state(TASK_INTERRUPTIBLE);
 362                         add_wait_queue(&kauditd_wait, &wait);
 363
 364                         if (!skb_queue_len(&audit_skb_queue)) {
 365                                 try_to_freeze();
 366                                 schedule();
 367                         }
 368
 369                         __set_current_state(TASK_RUNNING);
 370                         remove_wait_queue(&kauditd_wait, &wait);
 371                 }
 372         }
 373         return 0;
 374 }
 375
 376 int audit_send_list(void *_dest)
 377 {
 378         struct audit_netlink_list *dest = _dest;
 379         int pid = dest->pid;
 380         struct sk_buff *skb;
 381
 382         /* wait for parent to finish and send an ACK */
 383         mutex_lock(&audit_cmd_mutex);
 384         mutex_unlock(&audit_cmd_mutex);
 385
 386         while ((skb = __skb_dequeue(&dest->q)) != NULL)
 387                 netlink_unicast(audit_sock, skb, pid, 0);
 388
 389         kfree(dest);
 390
 391         return 0;
 392 }
 393
 394 struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
 395                                  int multi, void *payload, int size)
 396 {
 397         struct sk_buff  *skb;
 398         struct nlmsghdr *nlh;
 399         int             len = NLMSG_SPACE(size);
 400         void            *data;
 401         int             flags = multi ? NLM_F_MULTI : 0;
 402         int             t     = done  ? NLMSG_DONE  : type;
 403
 404         skb = alloc_skb(len, GFP_KERNEL);
 405         if (!skb)
 406                 return NULL;
 407
 408         nlh              = NLMSG_PUT(skb, pid, seq, t, size);
 409         nlh->nlmsg_flags = flags;
 410         data             = NLMSG_DATA(nlh);
 411         memcpy(data, payload, size);
 412         return skb;
 413
 414 nlmsg_failure:                  /* Used by NLMSG_PUT */
 415         if (skb)
 416                 kfree_skb(skb);
 417         return NULL;
 418 }
 419
 420 /**
 421  * audit_send_reply - send an audit reply message via netlink
 422  * @pid: process id to send reply to
 423  * @seq: sequence number
 424  * @type: audit message type
 425  * @done: done (last) flag
 426  * @multi: multi-part message flag
 427  * @payload: payload data
 428  * @size: payload size
 429  *
 430  * Allocates an skb, builds the netlink message, and sends it to the pid.
 431  * No failure notifications.
 432  */
 433 void audit_send_reply(int pid, int seq, int type, int done, int multi,
 434                       void *payload, int size)
 435 {
 436         struct sk_buff  *skb;
 437         skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
 438         if (!skb)
 439                 return;
 440         /* Ignore failure. It'll only happen if the sender goes away,
 441            because our timeout is set to infinite. */
 442         netlink_unicast(audit_sock, skb, pid, 0);
 443         return;
 444 }
 445
 446 /*
 447  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 448  * control messages.
 449  */
 450 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 451 {
 452         int err = 0;
 453
 454         switch (msg_type) {
 455         case AUDIT_GET:
 456         case AUDIT_LIST:
 457         case AUDIT_LIST_RULES:
 458         case AUDIT_SET:
 459         case AUDIT_ADD:
 460         case AUDIT_ADD_RULE:
 461         case AUDIT_DEL:
 462         case AUDIT_DEL_RULE:
 463         case AUDIT_SIGNAL_INFO:
 464                 if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
 465                         err = -EPERM;
 466                 break;
 467         case AUDIT_USER:
 468         case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
 469         case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2:
 470                 if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
 471                         err = -EPERM;
 472                 break;
 473         default:  /* bad msg */
 474                 err = -EINVAL;
 475         }
 476
 477         return err;
 478 }
 479
 480 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 481 {
 482         u32                     uid, pid, seq, sid;
 483         void                    *data;
 484         struct audit_status     *status_get, status_set;
 485         int                     err;
 486         struct audit_buffer     *ab;
 487         u16                     msg_type = nlh->nlmsg_type;
 488         uid_t                   loginuid; /* loginuid of sender */
 489         struct audit_sig_info   *sig_data;
 490         char                    *ctx;
 491         u32                     len;
 492
 493         err = audit_netlink_ok(skb, msg_type);
 494         if (err)
 495                 return err;
 496
 497         /* As soon as there's any sign of userspace auditd,
 498          * start kauditd to talk to it */
 499         if (!kauditd_task)
 500                 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
 501         if (IS_ERR(kauditd_task)) {
 502                 err = PTR_ERR(kauditd_task);
 503                 kauditd_task = NULL;
 504                 return err;
 505         }
 506
 507         pid  = NETLINK_CREDS(skb)->pid;
 508         uid  = NETLINK_CREDS(skb)->uid;
 509         loginuid = NETLINK_CB(skb).loginuid;
 510         sid  = NETLINK_CB(skb).sid;
 511         seq  = nlh->nlmsg_seq;
 512         data = NLMSG_DATA(nlh);
 513
 514         switch (msg_type) {
 515         case AUDIT_GET:
 516                 status_set.enabled       = audit_enabled;
 517                 status_set.failure       = audit_failure;
 518                 status_set.pid           = audit_pid;
 519                 status_set.rate_limit    = audit_rate_limit;
 520                 status_set.backlog_limit = audit_backlog_limit;
 521                 status_set.lost          = atomic_read(&audit_lost);
 522                 status_set.backlog       = skb_queue_len(&audit_skb_queue);
 523                 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
 524                                  &status_set, sizeof(status_set));
 525                 break;
 526         case AUDIT_SET:
 527                 if (nlh->nlmsg_len < sizeof(struct audit_status))
 528                         return -EINVAL;
 529                 status_get   = (struct audit_status *)data;
 530                 if (status_get->mask & AUDIT_STATUS_ENABLED) {
 531                         err = audit_set_enabled(status_get->enabled,
 532                                                         loginuid, sid);
 533                         if (err < 0) return err;
 534                 }
 535                 if (status_get->mask & AUDIT_STATUS_FAILURE) {
 536                         err = audit_set_failure(status_get->failure,
 537                                                          loginuid, sid);
 538                         if (err < 0) return err;
 539                 }
 540                 if (status_get->mask & AUDIT_STATUS_PID) {
 541                         int old   = audit_pid;
 542                         if (sid) {
 543                                 if ((err = selinux_sid_to_string(
 544                                                 sid, &ctx, &len)))
 545                                         return err;
 546                                 else
 547                                         audit_log(NULL, GFP_KERNEL,
 548                                                 AUDIT_CONFIG_CHANGE,
 549                                                 "audit_pid=%d old=%d by auid=%u subj=%s",
 550                                                 status_get->pid, old,
 551                                                 loginuid, ctx);
 552                                 kfree(ctx);
 553                         } else
 554                                 audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
 555                                         "audit_pid=%d old=%d by auid=%u",
 556                                           status_get->pid, old, loginuid);
 557                         audit_pid = status_get->pid;
 558                 }
 559                 if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
 560                         err = audit_set_rate_limit(status_get->rate_limit,
 561                                                          loginuid, sid);
 562                 if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
 563                         err = audit_set_backlog_limit(status_get->backlog_limit,
 564                                                         loginuid, sid);
 565                 break;
 566         case AUDIT_USER:
 567         case AUDIT_FIRST_USER_MSG...AUDIT_LAST_USER_MSG:
 568         case AUDIT_FIRST_USER_MSG2...AUDIT_LAST_USER_MSG2:
 569                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
 570                         return 0;
 571
 572                 err = audit_filter_user(&NETLINK_CB(skb), msg_type);
 573                 if (err == 1) {
 574                         err = 0;
 575                         ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
 576                         if (ab) {
 577                                 audit_log_format(ab,
 578                                                  "user pid=%d uid=%u auid=%u",
 579                                                  pid, uid, loginuid);
 580                                 if (sid) {
 581                                         if (selinux_sid_to_string(
 582                                                         sid, &ctx, &len)) {
 583                                                 audit_log_format(ab,
 584                                                         " ssid=%u", sid);
 585                                                 /* Maybe call audit_panic? */
 586                                         } else
 587                                                 audit_log_format(ab,
 588                                                         " subj=%s", ctx);
 589                                         kfree(ctx);
 590                                 }
 591                                 audit_log_format(ab, " msg='%.1024s'",
 592                                          (char *)data);
 593                                 audit_set_pid(ab, pid);
 594                                 audit_log_end(ab);
 595                         }
 596                 }
 597                 break;
 598         case AUDIT_ADD:
 599         case AUDIT_DEL:
 600                 if (nlmsg_len(nlh) < sizeof(struct audit_rule))
 601                         return -EINVAL;
 602                 /* fallthrough */
 603         case AUDIT_LIST:
 604                 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
 605                                            uid, seq, data, nlmsg_len(nlh),
 606                                            loginuid, sid);
 607                 break;
 608         case AUDIT_ADD_RULE:
 609         case AUDIT_DEL_RULE:
 610                 if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
 611                         return -EINVAL;
 612                 /* fallthrough */
 613         case AUDIT_LIST_RULES:
 614                 err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
 615                                            uid, seq, data, nlmsg_len(nlh),
 616                                            loginuid, sid);
 617                 break;
 618         case AUDIT_SIGNAL_INFO:
 619                 err = selinux_sid_to_string(audit_sig_sid, &ctx, &len);
 620                 if (err)
 621                         return err;
 622                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
 623                 if (!sig_data) {
 624                         kfree(ctx);
 625                         return -ENOMEM;
 626                 }
 627                 sig_data->uid = audit_sig_uid;
 628                 sig_data->pid = audit_sig_pid;
 629                 memcpy(sig_data->ctx, ctx, len);
 630                 kfree(ctx);
 631                 audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
 632                                 0, 0, sig_data, sizeof(*sig_data) + len);
 633                 kfree(sig_data);
 634                 break;
 635         default:
 636                 err = -EINVAL;
 637                 break;
 638         }
 639
 640         return err < 0 ? err : 0;
 641 }
 642
 643 /*
 644  * Get message from skb (based on rtnetlink_rcv_skb).  Each message is
 645  * processed by audit_receive_msg.  Malformed skbs with wrong length are
 646  * discarded silently.
 647  */
 648 static void audit_receive_skb(struct sk_buff *skb)
 649 {
 650         int             err;
 651         struct nlmsghdr *nlh;
 652         u32             rlen;
 653
 654         while (skb->len >= NLMSG_SPACE(0)) {
 655                 nlh = (struct nlmsghdr *)skb->data;
 656                 if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 657                         return;
 658                 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
 659                 if (rlen > skb->len)
 660                         rlen = skb->len;
 661                 if ((err = audit_receive_msg(skb, nlh))) {
 662                         netlink_ack(skb, nlh, err);
 663                 } else if (nlh->nlmsg_flags & NLM_F_ACK)
 664                         netlink_ack(skb, nlh, 0);
 665                 skb_pull(skb, rlen);
 666         }
 667 }
 668
 669 /* Receive messages from netlink socket. */
 670 static void audit_receive(struct sock *sk, int length)
 671 {
 672         struct sk_buff  *skb;
 673         unsigned int qlen;
 674
 675         mutex_lock(&audit_cmd_mutex);
 676
 677         for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) {
 678                 skb = skb_dequeue(&sk->sk_receive_queue);
 679                 audit_receive_skb(skb);
 680                 kfree_skb(skb);
 681         }
 682         mutex_unlock(&audit_cmd_mutex);
 683 }
 684
 685 #ifdef CONFIG_AUDITSYSCALL
 686 static const struct inotify_operations audit_inotify_ops = {
 687         .handle_event   = audit_handle_ievent,
 688         .destroy_watch  = audit_free_parent,
 689 };
 690 #endif
 691
 692 /* Initialize audit support at boot time. */
 693 static int __init audit_init(void)
 694 {
 695         int i;
 696
 697         printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
 698                audit_default ? "enabled" : "disabled");
 699         audit_sock = netlink_kernel_create(NETLINK_AUDIT, 0, audit_receive,
 700                                            THIS_MODULE);
 701         if (!audit_sock)
 702                 audit_panic("cannot initialize netlink socket");
 703         else
 704                 audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
 705
 706         skb_queue_head_init(&audit_skb_queue);
 707         audit_initialized = 1;
 708         audit_enabled = audit_default;
 709
 710         /* Register the callback with selinux.  This callback will be invoked
 711          * when a new policy is loaded. */
 712         selinux_audit_set_callback(&selinux_audit_rule_update);
 713
 714         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
 715
 716 #ifdef CONFIG_AUDITSYSCALL
 717         audit_ih = inotify_init(&audit_inotify_ops);
 718         if (IS_ERR(audit_ih))
 719                 audit_panic("cannot initialize inotify handle");
 720 #endif
 721
 722         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
 723                 INIT_LIST_HEAD(&audit_inode_hash[i]);
 724
 725         return 0;
 726 }
 727 __initcall(audit_init);
 728
 729 /* Process kernel command-line parameter at boot time.  audit=0 or audit=1. */
 730 static int __init audit_enable(char *str)
 731 {
 732         audit_default = !!simple_strtol(str, NULL, 0);
 733         printk(KERN_INFO "audit: %s%s\n",
 734                audit_default ? "enabled" : "disabled",
 735                audit_initialized ? "" : " (after initialization)");
 736         if (audit_initialized)
 737                 audit_enabled = audit_default;
 738         return 1;
 739 }
 740
 741 __setup("audit=", audit_enable);
 742
 743 static void audit_buffer_free(struct audit_buffer *ab)
 744 {
 745         unsigned long flags;
 746
 747         if (!ab)
 748                 return;
 749
 750         if (ab->skb)
 751                 kfree_skb(ab->skb);
 752
 753         spin_lock_irqsave(&audit_freelist_lock, flags);
 754         if (audit_freelist_count > AUDIT_MAXFREE)
 755                 kfree(ab);
 756         else {
 757                 audit_freelist_count++;
 758                 list_add(&ab->list, &audit_freelist);
 759         }
 760         spin_unlock_irqrestore(&audit_freelist_lock, flags);
 761 }
 762
 763 static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
 764                                                 gfp_t gfp_mask, int type)
 765 {
 766         unsigned long flags;
 767         struct audit_buffer *ab = NULL;
 768         struct nlmsghdr *nlh;
 769
 770         spin_lock_irqsave(&audit_freelist_lock, flags);
 771         if (!list_empty(&audit_freelist)) {
 772                 ab = list_entry(audit_freelist.next,
 773                                 struct audit_buffer, list);
 774                 list_del(&ab->list);
 775                 --audit_freelist_count;
 776         }
 777         spin_unlock_irqrestore(&audit_freelist_lock, flags);
 778
 779         if (!ab) {
 780                 ab = kmalloc(sizeof(*ab), gfp_mask);
 781                 if (!ab)
 782                         goto err;
 783         }
 784
 785         ab->skb = alloc_skb(AUDIT_BUFSIZ, gfp_mask);
 786         if (!ab->skb)
 787                 goto err;
 788
 789         ab->ctx = ctx;
 790         ab->gfp_mask = gfp_mask;
 791         nlh = (struct nlmsghdr *)skb_put(ab->skb, NLMSG_SPACE(0));
 792         nlh->nlmsg_type = type;
 793         nlh->nlmsg_flags = 0;
 794         nlh->nlmsg_pid = 0;
 795         nlh->nlmsg_seq = 0;
 796         return ab;
 797 err:
 798         audit_buffer_free(ab);
 799         return NULL;
 800 }
 801
 802 /**
 803  * audit_serial - compute a serial number for the audit record
 804  *
 805  * Compute a serial number for the audit record.  Audit records are
 806  * written to user-space as soon as they are generated, so a complete
 807  * audit record may be written in several pieces.  The timestamp of the
 808  * record and this serial number are used by the user-space tools to
 809  * determine which pieces belong to the same audit record.  The
 810  * (timestamp,serial) tuple is unique for each syscall and is live from
 811  * syscall entry to syscall exit.
 812  *
 813  * NOTE: Another possibility is to store the formatted records off the
 814  * audit context (for those records that have a context), and emit them
 815  * all at syscall exit.  However, this could delay the reporting of
 816  * significant errors until syscall exit (or never, if the system
 817  * halts).
 818  */
 819 unsigned int audit_serial(void)
 820 {
 821         static DEFINE_SPINLOCK(serial_lock);
 822         static unsigned int serial = 0;
 823
 824         unsigned long flags;
 825         unsigned int ret;
 826
 827         spin_lock_irqsave(&serial_lock, flags);
 828         do {
 829                 ret = ++serial;
 830         } while (unlikely(!ret));
 831         spin_unlock_irqrestore(&serial_lock, flags);
 832
 833         return ret;
 834 }
 835
 836 static inline void audit_get_stamp(struct audit_context *ctx,
 837                                    struct timespec *t, unsigned int *serial)
 838 {
 839         if (ctx)
 840                 auditsc_get_stamp(ctx, t, serial);
 841         else {
 842                 *t = CURRENT_TIME;
 843                 *serial = audit_serial();
 844         }
 845 }
 846
 847 /* Obtain an audit buffer.  This routine does locking to obtain the
 848  * audit buffer, but then no locking is required for calls to
 849  * audit_log_*format.  If the tsk is a task that is currently in a
 850  * syscall, then the syscall is marked as auditable and an audit record
 851  * will be written at syscall exit.  If there is no associated task, tsk
 852  * should be NULL. */
 853
 854 /**
 855  * audit_log_start - obtain an audit buffer
 856  * @ctx: audit_context (may be NULL)
 857  * @gfp_mask: type of allocation
 858  * @type: audit message type
 859  *
 860  * Returns audit_buffer pointer on success or NULL on error.
 861  *
 862  * Obtain an audit buffer.  This routine does locking to obtain the
 863  * audit buffer, but then no locking is required for calls to
 864  * audit_log_*format.  If the task (ctx) is a task that is currently in a
 865  * syscall, then the syscall is marked as auditable and an audit record
 866  * will be written at syscall exit.  If there is no associated task, then
 867  * task context (ctx) should be NULL.
 868  */
 869 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 870                                      int type)
 871 {
 872         struct audit_buffer     *ab     = NULL;
 873         struct timespec         t;
 874         unsigned int            serial;
 875         int reserve;
 876         unsigned long timeout_start = jiffies;
 877
 878         if (!audit_initialized)
 879                 return NULL;
 880
 881         if (unlikely(audit_filter_type(type)))
 882                 return NULL;
 883
 884         if (gfp_mask & __GFP_WAIT)
 885                 reserve = 0;
 886         else
 887                 reserve = 5; /* Allow atomic callers to go up to five
 888                                 entries over the normal backlog limit */
 889
 890         while (audit_backlog_limit
 891                && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
 892                 if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
 893                     && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
 894
 895                         /* Wait for auditd to drain the queue a little */
 896                         DECLARE_WAITQUEUE(wait, current);
 897                         set_current_state(TASK_INTERRUPTIBLE);
 898                         add_wait_queue(&audit_backlog_wait, &wait);
 899
 900                         if (audit_backlog_limit &&
 901                             skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
 902                                 schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
 903
 904                         __set_current_state(TASK_RUNNING);
 905                         remove_wait_queue(&audit_backlog_wait, &wait);
 906                         continue;
 907                 }
 908                 if (audit_rate_check())
 909                         printk(KERN_WARNING
 910                                "audit: audit_backlog=%d > "
 911                                "audit_backlog_limit=%d\n",
 912                                skb_queue_len(&audit_skb_queue),
 913                                audit_backlog_limit);
 914                 audit_log_lost("backlog limit exceeded");
 915                 audit_backlog_wait_time = audit_backlog_wait_overflow;
 916                 wake_up(&audit_backlog_wait);
 917                 return NULL;
 918         }
 919
 920         ab = audit_buffer_alloc(ctx, gfp_mask, type);
 921         if (!ab) {
 922                 audit_log_lost("out of memory in audit_log_start");
 923                 return NULL;
 924         }
 925
 926         audit_get_stamp(ab->ctx, &t, &serial);
 927
 928         audit_log_format(ab, "audit(%lu.%03lu:%u): ",
 929                          t.tv_sec, t.tv_nsec/1000000, serial);
 930         return ab;
 931 }
 932
 933 /**
 934  * audit_expand - expand skb in the audit buffer
 935  * @ab: audit_buffer
 936  * @extra: space to add at tail of the skb
 937  *
 938  * Returns 0 (no space) on failed expansion, or available space if
 939  * successful.
 940  */
 941 static inline int audit_expand(struct audit_buffer *ab, int extra)
 942 {
 943         struct sk_buff *skb = ab->skb;
 944         int ret = pskb_expand_head(skb, skb_headroom(skb), extra,
 945                                    ab->gfp_mask);
 946         if (ret < 0) {
 947                 audit_log_lost("out of memory in audit_expand");
 948                 return 0;
 949         }
 950         return skb_tailroom(skb);
 951 }
 952
 953 /*
 954  * Format an audit message into the audit buffer.  If there isn't enough
 955  * room in the audit buffer, more room will be allocated and vsnprint
 956  * will be called a second time.  Currently, we assume that a printk
 957  * can't format message larger than 1024 bytes, so we don't either.
 958  */
 959 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
 960                               va_list args)
 961 {
 962         int len, avail;
 963         struct sk_buff *skb;
 964         va_list args2;
 965
 966         if (!ab)
 967                 return;
 968
 969         BUG_ON(!ab->skb);
 970         skb = ab->skb;
 971         avail = skb_tailroom(skb);
 972         if (avail == 0) {
 973                 avail = audit_expand(ab, AUDIT_BUFSIZ);
 974                 if (!avail)
 975                         goto out;
 976         }
 977         va_copy(args2, args);
 978         len = vsnprintf(skb->tail, avail, fmt, args);
 979         if (len >= avail) {
 980                 /* The printk buffer is 1024 bytes long, so if we get
 981                  * here and AUDIT_BUFSIZ is at least 1024, then we can
 982                  * log everything that printk could have logged. */
 983                 avail = audit_expand(ab,
 984                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
 985                 if (!avail)
 986                         goto out;
 987                 len = vsnprintf(skb->tail, avail, fmt, args2);
 988         }
 989         if (len > 0)
 990                 skb_put(skb, len);
 991 out:
 992         return;
 993 }
 994
 995 /**
 996  * audit_log_format - format a message into the audit buffer.
 997  * @ab: audit_buffer
 998  * @fmt: format string
 999  * @...: optional parameters matching @fmt string
1000  *
1001  * All the work is done in audit_log_vformat.
1002  */
1003 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1004 {
1005         va_list args;
1006
1007         if (!ab)
1008                 return;
1009         va_start(args, fmt);
1010         audit_log_vformat(ab, fmt, args);
1011         va_end(args);
1012 }
1013
1014 /**
1015  * audit_log_hex - convert a buffer to hex and append it to the audit skb
1016  * @ab: the audit_buffer
1017  * @buf: buffer to convert to hex
1018  * @len: length of @buf to be converted
1019  *
1020  * No return value; failure to expand is silently ignored.
1021  *
1022  * This function will take the passed buf and convert it into a string of
1023  * ascii hex digits. The new string is placed onto the skb.
1024  */
1025 void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
1026                 size_t len)
1027 {
1028         int i, avail, new_len;
1029         unsigned char *ptr;
1030         struct sk_buff *skb;
1031         static const unsigned char *hex = "0123456789ABCDEF";
1032
1033         if (!ab)
1034                 return;
1035
1036         BUG_ON(!ab->skb);
1037         skb = ab->skb;
1038         avail = skb_tailroom(skb);
1039         new_len = len<<1;
1040         if (new_len >= avail) {
1041                 /* Round the buffer request up to the next multiple */
1042                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1043                 avail = audit_expand(ab, new_len);
1044                 if (!avail)
1045                         return;
1046         }
1047
1048         ptr = skb->tail;
1049         for (i=0; i<len; i++) {
1050                 *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1051                 *ptr++ = hex[buf[i] & 0x0F];      /* Lower nibble */
1052         }
1053         *ptr = 0;
1054         skb_put(skb, len << 1); /* new string is twice the old string */
1055 }
1056
1057 /*
1058  * Format a string of no more than slen characters into the audit buffer,
1059  * enclosed in quote marks.
1060  */
1061 static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
1062                                const char *string)
1063 {
1064         int avail, new_len;
1065         unsigned char *ptr;
1066         struct sk_buff *skb;
1067
1068         if (!ab)
1069                 return;
1070
1071         BUG_ON(!ab->skb);
1072         skb = ab->skb;
1073         avail = skb_tailroom(skb);
1074         new_len = slen + 3;     /* enclosing quotes + null terminator */
1075         if (new_len > avail) {
1076                 avail = audit_expand(ab, new_len);
1077                 if (!avail)
1078                         return;
1079         }
1080         ptr = skb->tail;
1081         *ptr++ = '"';
1082         memcpy(ptr, string, slen);
1083         ptr += slen;
1084         *ptr++ = '"';
1085         *ptr = 0;
1086         skb_put(skb, slen + 2); /* don't include null terminator */
1087 }
1088
1089 /**
1090  * audit_log_n_unstrustedstring - log a string that may contain random characters
1091  * @ab: audit_buffer
1092  * @len: lenth of string (not including trailing null)
1093  * @string: string to be logged
1094  *
1095  * This code will escape a string that is passed to it if the string
1096  * contains a control character, unprintable character, double quote mark,
1097  * or a space. Unescaped strings will start and end with a double quote mark.
1098  * Strings that are escaped are printed in hex (2 digits per char).
1099  *
1100  * The caller specifies the number of characters in the string to log, which may
1101  * or may not be the entire string.
1102  */
1103 const char *audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
1104                                         const char *string)
1105 {
1106         const unsigned char *p = string;
1107
1108         while (*p) {
1109                 if (*p == '"' || *p < 0x21 || *p > 0x7f) {
1110                         audit_log_hex(ab, string, len);
1111                         return string + len + 1;
1112                 }
1113                 p++;
1114         }
1115         audit_log_n_string(ab, len, string);
1116         return p + 1;
1117 }
1118
1119 /**
1120  * audit_log_unstrustedstring - log a string that may contain random characters
1121  * @ab: audit_buffer
1122  * @string: string to be logged
1123  *
1124  * Same as audit_log_n_unstrustedstring(), except that strlen is used to
1125  * determine string length.
1126  */
1127 const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1128 {
1129         return audit_log_n_untrustedstring(ab, strlen(string), string);
1130 }
1131
1132 /* This is a helper-function to print the escaped d_path */
1133 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1134                       struct dentry *dentry, struct vfsmount *vfsmnt)
1135 {
1136         char *p, *path;
1137
1138         if (prefix)
1139                 audit_log_format(ab, " %s", prefix);
1140
1141         /* We will allow 11 spaces for ' (deleted)' to be appended */
1142         path = kmalloc(PATH_MAX+11, ab->gfp_mask);
1143         if (!path) {
1144                 audit_log_format(ab, "<no memory>");
1145                 return;
1146         }
1147         p = d_path(dentry, vfsmnt, path, PATH_MAX+11);
1148         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1149                 /* FIXME: can we save some information here? */
1150                 audit_log_format(ab, "<too long>");
1151         } else
1152                 audit_log_untrustedstring(ab, p);
1153         kfree(path);
1154 }
1155
1156 /**
1157  * audit_log_end - end one audit record
1158  * @ab: the audit_buffer
1159  *
1160  * The netlink_* functions cannot be called inside an irq context, so
1161  * the audit buffer is placed on a queue and a tasklet is scheduled to
1162  * remove them from the queue outside the irq context.  May be called in
1163  * any context.
1164  */
1165 void audit_log_end(struct audit_buffer *ab)
1166 {
1167         if (!ab)
1168                 return;
1169         if (!audit_rate_check()) {
1170                 audit_log_lost("rate limit exceeded");
1171         } else {
1172                 if (audit_pid) {
1173                         struct nlmsghdr *nlh = (struct nlmsghdr *)ab->skb->data;
1174                         nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1175                         skb_queue_tail(&audit_skb_queue, ab->skb);
1176                         ab->skb = NULL;
1177                         wake_up_interruptible(&kauditd_wait);
1178                 } else {
1179                         printk(KERN_NOTICE "%s\n", ab->skb->data + NLMSG_SPACE(0));
1180                 }
1181         }
1182         audit_buffer_free(ab);
1183 }
1184
1185 /**
1186  * audit_log - Log an audit record
1187  * @ctx: audit context
1188  * @gfp_mask: type of allocation
1189  * @type: audit message type
1190  * @fmt: format string to use
1191  * @...: variable parameters matching the format string
1192  *
1193  * This is a convenience function that calls audit_log_start,
1194  * audit_log_vformat, and audit_log_end.  It may be called
1195  * in any context.
1196  */
1197 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1198                const char *fmt, ...)
1199 {
1200         struct audit_buffer *ab;
1201         va_list args;
1202
1203         ab = audit_log_start(ctx, gfp_mask, type);
1204         if (ab) {
1205                 va_start(args, fmt);
1206                 audit_log_vformat(ab, fmt, args);
1207                 va_end(args);
1208                 audit_log_end(ab);
1209         }
1210 }
1211
1212 EXPORT_SYMBOL(audit_log_start);
1213 EXPORT_SYMBOL(audit_log_end);
1214 EXPORT_SYMBOL(audit_log_format);
1215 EXPORT_SYMBOL(audit_log);