root/kernel/audit.c

DEFINITIONS

1. auditd_test_task
2. audit_ctl_lock
3. audit_ctl_unlock
4. audit_ctl_owner_current
5. auditd_pid_vnr
6. audit_get_sk
7. audit_panic
8. audit_rate_check
9. audit_log_lost
10. audit_log_config_change
11. audit_do_config_change
12. audit_set_rate_limit
13. audit_set_backlog_limit
14. audit_set_backlog_wait_time
15. audit_set_enabled
16. audit_set_failure
17. auditd_conn_free
18. auditd_set
19. kauditd_printk_skb
20. kauditd_rehold_skb
21. kauditd_hold_skb
22. kauditd_retry_skb
23. auditd_reset
24. auditd_send_unicast_skb
25. kauditd_send_queue
26. kauditd_send_multicast_skb
27. kauditd_thread
28. audit_send_list
29. audit_make_reply
30. audit_send_reply_thread
31. audit_send_reply
32. audit_netlink_ok
33. audit_log_common_recv_msg
34. audit_log_user_recv_msg
35. is_audit_feature_set
36. audit_get_feature
37. audit_log_feature_change
38. audit_set_feature
39. audit_replace
40. audit_receive_msg
41. audit_receive
42. audit_bind
43. audit_net_init
44. audit_net_exit
45. audit_init
46. audit_enable
47. audit_backlog_limit_set
48. audit_buffer_free
49. audit_buffer_alloc
50. audit_serial
51. audit_get_stamp
52. audit_log_start
53. audit_expand
54. audit_log_vformat
55. audit_log_format
56. audit_log_n_hex
57. audit_log_n_string
58. audit_string_contains_control
59. audit_log_n_untrustedstring
60. audit_log_untrustedstring
61. audit_log_d_path
62. audit_log_session_info
63. audit_log_key
64. audit_log_task_context
65. audit_log_d_path_exe
66. audit_get_tty
67. audit_put_tty
68. audit_log_task_info
69. audit_log_link_denied
70. audit_set_loginuid_perm
71. audit_log_set_loginuid
72. audit_set_loginuid
73. audit_signal_info
74. audit_log_end
75. audit_log

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* audit.c -- Auditing support
   3  * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
   4  * System-call specific features have moved to auditsc.c
   5  *
   6  * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
   7  * All Rights Reserved.
   8  *
   9  * Written by Rickard E. (Rik) Faith <faith@redhat.com>
  10  *
  11  * Goals: 1) Integrate fully with Security Modules.
  12  *        2) Minimal run-time overhead:
  13  *           a) Minimal when syscall auditing is disabled (audit_enable=0).
  14  *           b) Small when syscall auditing is enabled and no audit record
  15  *              is generated (defer as much work as possible to record
  16  *              generation time):
  17  *              i) context is allocated,
  18  *              ii) names from getname are stored without a copy, and
  19  *              iii) inode information stored from path_lookup.
  20  *        3) Ability to disable syscall auditing at boot time (audit=0).
  21  *        4) Usable by other parts of the kernel (if audit_log* is called,
  22  *           then a syscall record will be generated automatically for the
  23  *           current syscall).
  24  *        5) Netlink interface to user-space.
  25  *        6) Support low-overhead kernel-based filtering to minimize the
  26  *           information that must be passed to user-space.
  27  *
  28  * Audit userspace, documentation, tests, and bug/issue trackers:
  29  *      https://github.com/linux-audit
  30  */
  31 
  32 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  33 
  34 #include <linux/file.h>
  35 #include <linux/init.h>
  36 #include <linux/types.h>
  37 #include <linux/atomic.h>
  38 #include <linux/mm.h>
  39 #include <linux/export.h>
  40 #include <linux/slab.h>
  41 #include <linux/err.h>
  42 #include <linux/kthread.h>
  43 #include <linux/kernel.h>
  44 #include <linux/syscalls.h>
  45 #include <linux/spinlock.h>
  46 #include <linux/rcupdate.h>
  47 #include <linux/mutex.h>
  48 #include <linux/gfp.h>
  49 #include <linux/pid.h>
  50 
  51 #include <linux/audit.h>
  52 
  53 #include <net/sock.h>
  54 #include <net/netlink.h>
  55 #include <linux/skbuff.h>
  56 #ifdef CONFIG_SECURITY
  57 #include <linux/security.h>
  58 #endif
  59 #include <linux/freezer.h>
  60 #include <linux/pid_namespace.h>
  61 #include <net/netns/generic.h>
  62 
  63 #include "audit.h"
  64 
  65 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
  66  * (Initialization happens after skb_init is called.) */
  67 #define AUDIT_DISABLED          -1
  68 #define AUDIT_UNINITIALIZED     0
  69 #define AUDIT_INITIALIZED       1
  70 static int      audit_initialized;
  71 
  72 u32             audit_enabled = AUDIT_OFF;
  73 bool            audit_ever_enabled = !!AUDIT_OFF;
  74 
  75 EXPORT_SYMBOL_GPL(audit_enabled);
  76 
  77 /* Default state when kernel boots without any parameters. */
  78 static u32      audit_default = AUDIT_OFF;
  79 
  80 /* If auditing cannot proceed, audit_failure selects what happens. */
  81 static u32      audit_failure = AUDIT_FAIL_PRINTK;
  82 
  83 /* private audit network namespace index */
  84 static unsigned int audit_net_id;
  85 
  86 /**
  87  * struct audit_net - audit private network namespace data
  88  * @sk: communication socket
  89  */
  90 struct audit_net {
  91         struct sock *sk;
  92 };
  93 
  94 /**
  95  * struct auditd_connection - kernel/auditd connection state
  96  * @pid: auditd PID
  97  * @portid: netlink portid
  98  * @net: the associated network namespace
  99  * @rcu: RCU head
 100  *
 101  * Description:
 102  * This struct is RCU protected; you must either hold the RCU lock for reading
 103  * or the associated spinlock for writing.
 104  */
 105 static struct auditd_connection {
 106         struct pid *pid;
 107         u32 portid;
 108         struct net *net;
 109         struct rcu_head rcu;
 110 } *auditd_conn = NULL;
 111 static DEFINE_SPINLOCK(auditd_conn_lock);
 112 
 113 /* If audit_rate_limit is non-zero, limit the rate of sending audit records
 114  * to that number per second.  This prevents DoS attacks, but results in
 115  * audit records being dropped. */
 116 static u32      audit_rate_limit;
 117 
 118 /* Number of outstanding audit_buffers allowed.
 119  * When set to zero, this means unlimited. */
 120 static u32      audit_backlog_limit = 64;
 121 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
 122 static u32      audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
 123 
 124 /* The identity of the user shutting down the audit system. */
 125 kuid_t          audit_sig_uid = INVALID_UID;
 126 pid_t           audit_sig_pid = -1;
 127 u32             audit_sig_sid = 0;
 128 
 129 /* Records can be lost in several ways:
 130    0) [suppressed in audit_alloc]
 131    1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
 132    2) out of memory in audit_log_move [alloc_skb]
 133    3) suppressed due to audit_rate_limit
 134    4) suppressed due to audit_backlog_limit
 135 */
 136 static atomic_t audit_lost = ATOMIC_INIT(0);
 137 
 138 /* Hash for inode-based rules */
 139 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 140 
 141 static struct kmem_cache *audit_buffer_cache;
 142 
 143 /* queue msgs to send via kauditd_task */
 144 static struct sk_buff_head audit_queue;
 145 /* queue msgs due to temporary unicast send problems */
 146 static struct sk_buff_head audit_retry_queue;
 147 /* queue msgs waiting for new auditd connection */
 148 static struct sk_buff_head audit_hold_queue;
 149 
 150 /* queue servicing thread */
 151 static struct task_struct *kauditd_task;
 152 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
 153 
 154 /* waitqueue for callers who are blocked on the audit backlog */
 155 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
 156 
 157 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
 158                                    .mask = -1,
 159                                    .features = 0,
 160                                    .lock = 0,};
 161 
 162 static char *audit_feature_names[2] = {
 163         "only_unset_loginuid",
 164         "loginuid_immutable",
 165 };
 166 
 167 /**
 168  * struct audit_ctl_mutex - serialize requests from userspace
 169  * @lock: the mutex used for locking
 170  * @owner: the task which owns the lock
 171  *
 172  * Description:
 173  * This is the lock struct used to ensure we only process userspace requests
 174  * in an orderly fashion.  We can't simply use a mutex/lock here because we
 175  * need to track lock ownership so we don't end up blocking the lock owner in
 176  * audit_log_start() or similar.
 177  */
 178 static struct audit_ctl_mutex {
 179         struct mutex lock;
 180         void *owner;
 181 } audit_cmd_mutex;
 182 
 183 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
 184  * audit records.  Since printk uses a 1024 byte buffer, this buffer
 185  * should be at least that large. */
 186 #define AUDIT_BUFSIZ 1024
 187 
 188 /* The audit_buffer is used when formatting an audit record.  The caller
 189  * locks briefly to get the record off the freelist or to allocate the
 190  * buffer, and locks briefly to send the buffer to the netlink layer or
 191  * to place it on a transmit queue.  Multiple audit_buffers can be in
 192  * use simultaneously. */
 193 struct audit_buffer {
 194         struct sk_buff       *skb;      /* formatted skb ready to send */
 195         struct audit_context *ctx;      /* NULL or associated context */
 196         gfp_t                gfp_mask;
 197 };
 198 
 199 struct audit_reply {
 200         __u32 portid;
 201         struct net *net;
 202         struct sk_buff *skb;
 203 };
 204 
 205 /**
 206  * auditd_test_task - Check to see if a given task is an audit daemon
 207  * @task: the task to check
 208  *
 209  * Description:
 210  * Return 1 if the task is a registered audit daemon, 0 otherwise.
 211  */
 212 int auditd_test_task(struct task_struct *task)
 213 {
 214         int rc;
 215         struct auditd_connection *ac;
 216 
 217         rcu_read_lock();
 218         ac = rcu_dereference(auditd_conn);
 219         rc = (ac && ac->pid == task_tgid(task) ? 1 : 0);
 220         rcu_read_unlock();
 221 
 222         return rc;
 223 }
 224 
 225 /**
 226  * audit_ctl_lock - Take the audit control lock
 227  */
 228 void audit_ctl_lock(void)
 229 {
 230         mutex_lock(&audit_cmd_mutex.lock);
 231         audit_cmd_mutex.owner = current;
 232 }
 233 
 234 /**
 235  * audit_ctl_unlock - Drop the audit control lock
 236  */
 237 void audit_ctl_unlock(void)
 238 {
 239         audit_cmd_mutex.owner = NULL;
 240         mutex_unlock(&audit_cmd_mutex.lock);
 241 }
 242 
 243 /**
 244  * audit_ctl_owner_current - Test to see if the current task owns the lock
 245  *
 246  * Description:
 247  * Return true if the current task owns the audit control lock, false if it
 248  * doesn't own the lock.
 249  */
 250 static bool audit_ctl_owner_current(void)
 251 {
 252         return (current == audit_cmd_mutex.owner);
 253 }
 254 
 255 /**
 256  * auditd_pid_vnr - Return the auditd PID relative to the namespace
 257  *
 258  * Description:
 259  * Returns the PID in relation to the namespace, 0 on failure.
 260  */
 261 static pid_t auditd_pid_vnr(void)
 262 {
 263         pid_t pid;
 264         const struct auditd_connection *ac;
 265 
 266         rcu_read_lock();
 267         ac = rcu_dereference(auditd_conn);
 268         if (!ac || !ac->pid)
 269                 pid = 0;
 270         else
 271                 pid = pid_vnr(ac->pid);
 272         rcu_read_unlock();
 273 
 274         return pid;
 275 }
 276 
 277 /**
 278  * audit_get_sk - Return the audit socket for the given network namespace
 279  * @net: the destination network namespace
 280  *
 281  * Description:
 282  * Returns the sock pointer if valid, NULL otherwise.  The caller must ensure
 283  * that a reference is held for the network namespace while the sock is in use.
 284  */
 285 static struct sock *audit_get_sk(const struct net *net)
 286 {
 287         struct audit_net *aunet;
 288 
 289         if (!net)
 290                 return NULL;
 291 
 292         aunet = net_generic(net, audit_net_id);
 293         return aunet->sk;
 294 }
 295 
 296 void audit_panic(const char *message)
 297 {
 298         switch (audit_failure) {
 299         case AUDIT_FAIL_SILENT:
 300                 break;
 301         case AUDIT_FAIL_PRINTK:
 302                 if (printk_ratelimit())
 303                         pr_err("%s\n", message);
 304                 break;
 305         case AUDIT_FAIL_PANIC:
 306                 panic("audit: %s\n", message);
 307                 break;
 308         }
 309 }
 310 
 311 static inline int audit_rate_check(void)
 312 {
 313         static unsigned long    last_check = 0;
 314         static int              messages   = 0;
 315         static DEFINE_SPINLOCK(lock);
 316         unsigned long           flags;
 317         unsigned long           now;
 318         unsigned long           elapsed;
 319         int                     retval     = 0;
 320 
 321         if (!audit_rate_limit) return 1;
 322 
 323         spin_lock_irqsave(&lock, flags);
 324         if (++messages < audit_rate_limit) {
 325                 retval = 1;
 326         } else {
 327                 now     = jiffies;
 328                 elapsed = now - last_check;
 329                 if (elapsed > HZ) {
 330                         last_check = now;
 331                         messages   = 0;
 332                         retval     = 1;
 333                 }
 334         }
 335         spin_unlock_irqrestore(&lock, flags);
 336 
 337         return retval;
 338 }
 339 
 340 /**
 341  * audit_log_lost - conditionally log lost audit message event
 342  * @message: the message stating reason for lost audit message
 343  *
 344  * Emit at least 1 message per second, even if audit_rate_check is
 345  * throttling.
 346  * Always increment the lost messages counter.
 347 */
 348 void audit_log_lost(const char *message)
 349 {
 350         static unsigned long    last_msg = 0;
 351         static DEFINE_SPINLOCK(lock);
 352         unsigned long           flags;
 353         unsigned long           now;
 354         int                     print;
 355 
 356         atomic_inc(&audit_lost);
 357 
 358         print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
 359 
 360         if (!print) {
 361                 spin_lock_irqsave(&lock, flags);
 362                 now = jiffies;
 363                 if (now - last_msg > HZ) {
 364                         print = 1;
 365                         last_msg = now;
 366                 }
 367                 spin_unlock_irqrestore(&lock, flags);
 368         }
 369 
 370         if (print) {
 371                 if (printk_ratelimit())
 372                         pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
 373                                 atomic_read(&audit_lost),
 374                                 audit_rate_limit,
 375                                 audit_backlog_limit);
 376                 audit_panic(message);
 377         }
 378 }
 379 
 380 static int audit_log_config_change(char *function_name, u32 new, u32 old,
 381                                    int allow_changes)
 382 {
 383         struct audit_buffer *ab;
 384         int rc = 0;
 385 
 386         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 387         if (unlikely(!ab))
 388                 return rc;
 389         audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old);
 390         audit_log_session_info(ab);
 391         rc = audit_log_task_context(ab);
 392         if (rc)
 393                 allow_changes = 0; /* Something weird, deny request */
 394         audit_log_format(ab, " res=%d", allow_changes);
 395         audit_log_end(ab);
 396         return rc;
 397 }
 398 
 399 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
 400 {
 401         int allow_changes, rc = 0;
 402         u32 old = *to_change;
 403 
 404         /* check if we are locked */
 405         if (audit_enabled == AUDIT_LOCKED)
 406                 allow_changes = 0;
 407         else
 408                 allow_changes = 1;
 409 
 410         if (audit_enabled != AUDIT_OFF) {
 411                 rc = audit_log_config_change(function_name, new, old, allow_changes);
 412                 if (rc)
 413                         allow_changes = 0;
 414         }
 415 
 416         /* If we are allowed, make the change */
 417         if (allow_changes == 1)
 418                 *to_change = new;
 419         /* Not allowed, update reason */
 420         else if (rc == 0)
 421                 rc = -EPERM;
 422         return rc;
 423 }
 424 
 425 static int audit_set_rate_limit(u32 limit)
 426 {
 427         return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
 428 }
 429 
 430 static int audit_set_backlog_limit(u32 limit)
 431 {
 432         return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
 433 }
 434 
 435 static int audit_set_backlog_wait_time(u32 timeout)
 436 {
 437         return audit_do_config_change("audit_backlog_wait_time",
 438                                       &audit_backlog_wait_time, timeout);
 439 }
 440 
 441 static int audit_set_enabled(u32 state)
 442 {
 443         int rc;
 444         if (state > AUDIT_LOCKED)
 445                 return -EINVAL;
 446 
 447         rc =  audit_do_config_change("audit_enabled", &audit_enabled, state);
 448         if (!rc)
 449                 audit_ever_enabled |= !!state;
 450 
 451         return rc;
 452 }
 453 
 454 static int audit_set_failure(u32 state)
 455 {
 456         if (state != AUDIT_FAIL_SILENT
 457             && state != AUDIT_FAIL_PRINTK
 458             && state != AUDIT_FAIL_PANIC)
 459                 return -EINVAL;
 460 
 461         return audit_do_config_change("audit_failure", &audit_failure, state);
 462 }
 463 
 464 /**
 465  * auditd_conn_free - RCU helper to release an auditd connection struct
 466  * @rcu: RCU head
 467  *
 468  * Description:
 469  * Drop any references inside the auditd connection tracking struct and free
 470  * the memory.
 471  */
 472 static void auditd_conn_free(struct rcu_head *rcu)
 473 {
 474         struct auditd_connection *ac;
 475 
 476         ac = container_of(rcu, struct auditd_connection, rcu);
 477         put_pid(ac->pid);
 478         put_net(ac->net);
 479         kfree(ac);
 480 }
 481 
 482 /**
 483  * auditd_set - Set/Reset the auditd connection state
 484  * @pid: auditd PID
 485  * @portid: auditd netlink portid
 486  * @net: auditd network namespace pointer
 487  *
 488  * Description:
 489  * This function will obtain and drop network namespace references as
 490  * necessary.  Returns zero on success, negative values on failure.
 491  */
 492 static int auditd_set(struct pid *pid, u32 portid, struct net *net)
 493 {
 494         unsigned long flags;
 495         struct auditd_connection *ac_old, *ac_new;
 496 
 497         if (!pid || !net)
 498                 return -EINVAL;
 499 
 500         ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL);
 501         if (!ac_new)
 502                 return -ENOMEM;
 503         ac_new->pid = get_pid(pid);
 504         ac_new->portid = portid;
 505         ac_new->net = get_net(net);
 506 
 507         spin_lock_irqsave(&auditd_conn_lock, flags);
 508         ac_old = rcu_dereference_protected(auditd_conn,
 509                                            lockdep_is_held(&auditd_conn_lock));
 510         rcu_assign_pointer(auditd_conn, ac_new);
 511         spin_unlock_irqrestore(&auditd_conn_lock, flags);
 512 
 513         if (ac_old)
 514                 call_rcu(&ac_old->rcu, auditd_conn_free);
 515 
 516         return 0;
 517 }
 518 
 519 /**
 520  * kauditd_print_skb - Print the audit record to the ring buffer
 521  * @skb: audit record
 522  *
 523  * Whatever the reason, this packet may not make it to the auditd connection
 524  * so write it via printk so the information isn't completely lost.
 525  */
 526 static void kauditd_printk_skb(struct sk_buff *skb)
 527 {
 528         struct nlmsghdr *nlh = nlmsg_hdr(skb);
 529         char *data = nlmsg_data(nlh);
 530 
 531         if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit())
 532                 pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
 533 }
 534 
 535 /**
 536  * kauditd_rehold_skb - Handle a audit record send failure in the hold queue
 537  * @skb: audit record
 538  *
 539  * Description:
 540  * This should only be used by the kauditd_thread when it fails to flush the
 541  * hold queue.
 542  */
 543 static void kauditd_rehold_skb(struct sk_buff *skb)
 544 {
 545         /* put the record back in the queue at the same place */
 546         skb_queue_head(&audit_hold_queue, skb);
 547 }
 548 
 549 /**
 550  * kauditd_hold_skb - Queue an audit record, waiting for auditd
 551  * @skb: audit record
 552  *
 553  * Description:
 554  * Queue the audit record, waiting for an instance of auditd.  When this
 555  * function is called we haven't given up yet on sending the record, but things
 556  * are not looking good.  The first thing we want to do is try to write the
 557  * record via printk and then see if we want to try and hold on to the record
 558  * and queue it, if we have room.  If we want to hold on to the record, but we
 559  * don't have room, record a record lost message.
 560  */
 561 static void kauditd_hold_skb(struct sk_buff *skb)
 562 {
 563         /* at this point it is uncertain if we will ever send this to auditd so
 564          * try to send the message via printk before we go any further */
 565         kauditd_printk_skb(skb);
 566 
 567         /* can we just silently drop the message? */
 568         if (!audit_default) {
 569                 kfree_skb(skb);
 570                 return;
 571         }
 572 
 573         /* if we have room, queue the message */
 574         if (!audit_backlog_limit ||
 575             skb_queue_len(&audit_hold_queue) < audit_backlog_limit) {
 576                 skb_queue_tail(&audit_hold_queue, skb);
 577                 return;
 578         }
 579 
 580         /* we have no other options - drop the message */
 581         audit_log_lost("kauditd hold queue overflow");
 582         kfree_skb(skb);
 583 }
 584 
 585 /**
 586  * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd
 587  * @skb: audit record
 588  *
 589  * Description:
 590  * Not as serious as kauditd_hold_skb() as we still have a connected auditd,
 591  * but for some reason we are having problems sending it audit records so
 592  * queue the given record and attempt to resend.
 593  */
 594 static void kauditd_retry_skb(struct sk_buff *skb)
 595 {
 596         /* NOTE: because records should only live in the retry queue for a
 597          * short period of time, before either being sent or moved to the hold
 598          * queue, we don't currently enforce a limit on this queue */
 599         skb_queue_tail(&audit_retry_queue, skb);
 600 }
 601 
 602 /**
 603  * auditd_reset - Disconnect the auditd connection
 604  * @ac: auditd connection state
 605  *
 606  * Description:
 607  * Break the auditd/kauditd connection and move all the queued records into the
 608  * hold queue in case auditd reconnects.  It is important to note that the @ac
 609  * pointer should never be dereferenced inside this function as it may be NULL
 610  * or invalid, you can only compare the memory address!  If @ac is NULL then
 611  * the connection will always be reset.
 612  */
 613 static void auditd_reset(const struct auditd_connection *ac)
 614 {
 615         unsigned long flags;
 616         struct sk_buff *skb;
 617         struct auditd_connection *ac_old;
 618 
 619         /* if it isn't already broken, break the connection */
 620         spin_lock_irqsave(&auditd_conn_lock, flags);
 621         ac_old = rcu_dereference_protected(auditd_conn,
 622                                            lockdep_is_held(&auditd_conn_lock));
 623         if (ac && ac != ac_old) {
 624                 /* someone already registered a new auditd connection */
 625                 spin_unlock_irqrestore(&auditd_conn_lock, flags);
 626                 return;
 627         }
 628         rcu_assign_pointer(auditd_conn, NULL);
 629         spin_unlock_irqrestore(&auditd_conn_lock, flags);
 630 
 631         if (ac_old)
 632                 call_rcu(&ac_old->rcu, auditd_conn_free);
 633 
 634         /* flush the retry queue to the hold queue, but don't touch the main
 635          * queue since we need to process that normally for multicast */
 636         while ((skb = skb_dequeue(&audit_retry_queue)))
 637                 kauditd_hold_skb(skb);
 638 }
 639 
 640 /**
 641  * auditd_send_unicast_skb - Send a record via unicast to auditd
 642  * @skb: audit record
 643  *
 644  * Description:
 645  * Send a skb to the audit daemon, returns positive/zero values on success and
 646  * negative values on failure; in all cases the skb will be consumed by this
 647  * function.  If the send results in -ECONNREFUSED the connection with auditd
 648  * will be reset.  This function may sleep so callers should not hold any locks
 649  * where this would cause a problem.
 650  */
 651 static int auditd_send_unicast_skb(struct sk_buff *skb)
 652 {
 653         int rc;
 654         u32 portid;
 655         struct net *net;
 656         struct sock *sk;
 657         struct auditd_connection *ac;
 658 
 659         /* NOTE: we can't call netlink_unicast while in the RCU section so
 660          *       take a reference to the network namespace and grab local
 661          *       copies of the namespace, the sock, and the portid; the
 662          *       namespace and sock aren't going to go away while we hold a
 663          *       reference and if the portid does become invalid after the RCU
 664          *       section netlink_unicast() should safely return an error */
 665 
 666         rcu_read_lock();
 667         ac = rcu_dereference(auditd_conn);
 668         if (!ac) {
 669                 rcu_read_unlock();
 670                 kfree_skb(skb);
 671                 rc = -ECONNREFUSED;
 672                 goto err;
 673         }
 674         net = get_net(ac->net);
 675         sk = audit_get_sk(net);
 676         portid = ac->portid;
 677         rcu_read_unlock();
 678 
 679         rc = netlink_unicast(sk, skb, portid, 0);
 680         put_net(net);
 681         if (rc < 0)
 682                 goto err;
 683 
 684         return rc;
 685 
 686 err:
 687         if (ac && rc == -ECONNREFUSED)
 688                 auditd_reset(ac);
 689         return rc;
 690 }
 691 
 692 /**
 693  * kauditd_send_queue - Helper for kauditd_thread to flush skb queues
 694  * @sk: the sending sock
 695  * @portid: the netlink destination
 696  * @queue: the skb queue to process
 697  * @retry_limit: limit on number of netlink unicast failures
 698  * @skb_hook: per-skb hook for additional processing
 699  * @err_hook: hook called if the skb fails the netlink unicast send
 700  *
 701  * Description:
 702  * Run through the given queue and attempt to send the audit records to auditd,
 703  * returns zero on success, negative values on failure.  It is up to the caller
 704  * to ensure that the @sk is valid for the duration of this function.
 705  *
 706  */
 707 static int kauditd_send_queue(struct sock *sk, u32 portid,
 708                               struct sk_buff_head *queue,
 709                               unsigned int retry_limit,
 710                               void (*skb_hook)(struct sk_buff *skb),
 711                               void (*err_hook)(struct sk_buff *skb))
 712 {
 713         int rc = 0;
 714         struct sk_buff *skb;
 715         static unsigned int failed = 0;
 716 
 717         /* NOTE: kauditd_thread takes care of all our locking, we just use
 718          *       the netlink info passed to us (e.g. sk and portid) */
 719 
 720         while ((skb = skb_dequeue(queue))) {
 721                 /* call the skb_hook for each skb we touch */
 722                 if (skb_hook)
 723                         (*skb_hook)(skb);
 724 
 725                 /* can we send to anyone via unicast? */
 726                 if (!sk) {
 727                         if (err_hook)
 728                                 (*err_hook)(skb);
 729                         continue;
 730                 }
 731 
 732                 /* grab an extra skb reference in case of error */
 733                 skb_get(skb);
 734                 rc = netlink_unicast(sk, skb, portid, 0);
 735                 if (rc < 0) {
 736                         /* fatal failure for our queue flush attempt? */
 737                         if (++failed >= retry_limit ||
 738                             rc == -ECONNREFUSED || rc == -EPERM) {
 739                                 /* yes - error processing for the queue */
 740                                 sk = NULL;
 741                                 if (err_hook)
 742                                         (*err_hook)(skb);
 743                                 if (!skb_hook)
 744                                         goto out;
 745                                 /* keep processing with the skb_hook */
 746                                 continue;
 747                         } else
 748                                 /* no - requeue to preserve ordering */
 749                                 skb_queue_head(queue, skb);
 750                 } else {
 751                         /* it worked - drop the extra reference and continue */
 752                         consume_skb(skb);
 753                         failed = 0;
 754                 }
 755         }
 756 
 757 out:
 758         return (rc >= 0 ? 0 : rc);
 759 }
 760 
 761 /*
 762  * kauditd_send_multicast_skb - Send a record to any multicast listeners
 763  * @skb: audit record
 764  *
 765  * Description:
 766  * Write a multicast message to anyone listening in the initial network
 767  * namespace.  This function doesn't consume an skb as might be expected since
 768  * it has to copy it anyways.
 769  */
 770 static void kauditd_send_multicast_skb(struct sk_buff *skb)
 771 {
 772         struct sk_buff *copy;
 773         struct sock *sock = audit_get_sk(&init_net);
 774         struct nlmsghdr *nlh;
 775 
 776         /* NOTE: we are not taking an additional reference for init_net since
 777          *       we don't have to worry about it going away */
 778 
 779         if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
 780                 return;
 781 
 782         /*
 783          * The seemingly wasteful skb_copy() rather than bumping the refcount
 784          * using skb_get() is necessary because non-standard mods are made to
 785          * the skb by the original kaudit unicast socket send routine.  The
 786          * existing auditd daemon assumes this breakage.  Fixing this would
 787          * require co-ordinating a change in the established protocol between
 788          * the kaudit kernel subsystem and the auditd userspace code.  There is
 789          * no reason for new multicast clients to continue with this
 790          * non-compliance.
 791          */
 792         copy = skb_copy(skb, GFP_KERNEL);
 793         if (!copy)
 794                 return;
 795         nlh = nlmsg_hdr(copy);
 796         nlh->nlmsg_len = skb->len;
 797 
 798         nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
 799 }
 800 
 801 /**
 802  * kauditd_thread - Worker thread to send audit records to userspace
 803  * @dummy: unused
 804  */
 805 static int kauditd_thread(void *dummy)
 806 {
 807         int rc;
 808         u32 portid = 0;
 809         struct net *net = NULL;
 810         struct sock *sk = NULL;
 811         struct auditd_connection *ac;
 812 
 813 #define UNICAST_RETRIES 5
 814 
 815         set_freezable();
 816         while (!kthread_should_stop()) {
 817                 /* NOTE: see the lock comments in auditd_send_unicast_skb() */
 818                 rcu_read_lock();
 819                 ac = rcu_dereference(auditd_conn);
 820                 if (!ac) {
 821                         rcu_read_unlock();
 822                         goto main_queue;
 823                 }
 824                 net = get_net(ac->net);
 825                 sk = audit_get_sk(net);
 826                 portid = ac->portid;
 827                 rcu_read_unlock();
 828 
 829                 /* attempt to flush the hold queue */
 830                 rc = kauditd_send_queue(sk, portid,
 831                                         &audit_hold_queue, UNICAST_RETRIES,
 832                                         NULL, kauditd_rehold_skb);
 833                 if (ac && rc < 0) {
 834                         sk = NULL;
 835                         auditd_reset(ac);
 836                         goto main_queue;
 837                 }
 838 
 839                 /* attempt to flush the retry queue */
 840                 rc = kauditd_send_queue(sk, portid,
 841                                         &audit_retry_queue, UNICAST_RETRIES,
 842                                         NULL, kauditd_hold_skb);
 843                 if (ac && rc < 0) {
 844                         sk = NULL;
 845                         auditd_reset(ac);
 846                         goto main_queue;
 847                 }
 848 
 849 main_queue:
 850                 /* process the main queue - do the multicast send and attempt
 851                  * unicast, dump failed record sends to the retry queue; if
 852                  * sk == NULL due to previous failures we will just do the
 853                  * multicast send and move the record to the hold queue */
 854                 rc = kauditd_send_queue(sk, portid, &audit_queue, 1,
 855                                         kauditd_send_multicast_skb,
 856                                         (sk ?
 857                                          kauditd_retry_skb : kauditd_hold_skb));
 858                 if (ac && rc < 0)
 859                         auditd_reset(ac);
 860                 sk = NULL;
 861 
 862                 /* drop our netns reference, no auditd sends past this line */
 863                 if (net) {
 864                         put_net(net);
 865                         net = NULL;
 866                 }
 867 
 868                 /* we have processed all the queues so wake everyone */
 869                 wake_up(&audit_backlog_wait);
 870 
 871                 /* NOTE: we want to wake up if there is anything on the queue,
 872                  *       regardless of if an auditd is connected, as we need to
 873                  *       do the multicast send and rotate records from the
 874                  *       main queue to the retry/hold queues */
 875                 wait_event_freezable(kauditd_wait,
 876                                      (skb_queue_len(&audit_queue) ? 1 : 0));
 877         }
 878 
 879         return 0;
 880 }
 881 
 882 int audit_send_list(void *_dest)
 883 {
 884         struct audit_netlink_list *dest = _dest;
 885         struct sk_buff *skb;
 886         struct sock *sk = audit_get_sk(dest->net);
 887 
 888         /* wait for parent to finish and send an ACK */
 889         audit_ctl_lock();
 890         audit_ctl_unlock();
 891 
 892         while ((skb = __skb_dequeue(&dest->q)) != NULL)
 893                 netlink_unicast(sk, skb, dest->portid, 0);
 894 
 895         put_net(dest->net);
 896         kfree(dest);
 897 
 898         return 0;
 899 }
 900 
 901 struct sk_buff *audit_make_reply(int seq, int type, int done,
 902                                  int multi, const void *payload, int size)
 903 {
 904         struct sk_buff  *skb;
 905         struct nlmsghdr *nlh;
 906         void            *data;
 907         int             flags = multi ? NLM_F_MULTI : 0;
 908         int             t     = done  ? NLMSG_DONE  : type;
 909 
 910         skb = nlmsg_new(size, GFP_KERNEL);
 911         if (!skb)
 912                 return NULL;
 913 
 914         nlh     = nlmsg_put(skb, 0, seq, t, size, flags);
 915         if (!nlh)
 916                 goto out_kfree_skb;
 917         data = nlmsg_data(nlh);
 918         memcpy(data, payload, size);
 919         return skb;
 920 
 921 out_kfree_skb:
 922         kfree_skb(skb);
 923         return NULL;
 924 }
 925 
 926 static int audit_send_reply_thread(void *arg)
 927 {
 928         struct audit_reply *reply = (struct audit_reply *)arg;
 929         struct sock *sk = audit_get_sk(reply->net);
 930 
 931         audit_ctl_lock();
 932         audit_ctl_unlock();
 933 
 934         /* Ignore failure. It'll only happen if the sender goes away,
 935            because our timeout is set to infinite. */
 936         netlink_unicast(sk, reply->skb, reply->portid, 0);
 937         put_net(reply->net);
 938         kfree(reply);
 939         return 0;
 940 }
 941 
 942 /**
 943  * audit_send_reply - send an audit reply message via netlink
 944  * @request_skb: skb of request we are replying to (used to target the reply)
 945  * @seq: sequence number
 946  * @type: audit message type
 947  * @done: done (last) flag
 948  * @multi: multi-part message flag
 949  * @payload: payload data
 950  * @size: payload size
 951  *
 952  * Allocates an skb, builds the netlink message, and sends it to the port id.
 953  * No failure notifications.
 954  */
 955 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
 956                              int multi, const void *payload, int size)
 957 {
 958         struct net *net = sock_net(NETLINK_CB(request_skb).sk);
 959         struct sk_buff *skb;
 960         struct task_struct *tsk;
 961         struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
 962                                             GFP_KERNEL);
 963 
 964         if (!reply)
 965                 return;
 966 
 967         skb = audit_make_reply(seq, type, done, multi, payload, size);
 968         if (!skb)
 969                 goto out;
 970 
 971         reply->net = get_net(net);
 972         reply->portid = NETLINK_CB(request_skb).portid;
 973         reply->skb = skb;
 974 
 975         tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
 976         if (!IS_ERR(tsk))
 977                 return;
 978         kfree_skb(skb);
 979 out:
 980         kfree(reply);
 981 }
 982 
 983 /*
 984  * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
 985  * control messages.
 986  */
 987 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 988 {
 989         int err = 0;
 990 
 991         /* Only support initial user namespace for now. */
 992         /*
 993          * We return ECONNREFUSED because it tricks userspace into thinking
 994          * that audit was not configured into the kernel.  Lots of users
 995          * configure their PAM stack (because that's what the distro does)
 996          * to reject login if unable to send messages to audit.  If we return
 997          * ECONNREFUSED the PAM stack thinks the kernel does not have audit
 998          * configured in and will let login proceed.  If we return EPERM
 999          * userspace will reject all logins.  This should be removed when we
1000          * support non init namespaces!!
1001          */
1002         if (current_user_ns() != &init_user_ns)
1003                 return -ECONNREFUSED;
1004 
1005         switch (msg_type) {
1006         case AUDIT_LIST:
1007         case AUDIT_ADD:
1008         case AUDIT_DEL:
1009                 return -EOPNOTSUPP;
1010         case AUDIT_GET:
1011         case AUDIT_SET:
1012         case AUDIT_GET_FEATURE:
1013         case AUDIT_SET_FEATURE:
1014         case AUDIT_LIST_RULES:
1015         case AUDIT_ADD_RULE:
1016         case AUDIT_DEL_RULE:
1017         case AUDIT_SIGNAL_INFO:
1018         case AUDIT_TTY_GET:
1019         case AUDIT_TTY_SET:
1020         case AUDIT_TRIM:
1021         case AUDIT_MAKE_EQUIV:
1022                 /* Only support auditd and auditctl in initial pid namespace
1023                  * for now. */
1024                 if (task_active_pid_ns(current) != &init_pid_ns)
1025                         return -EPERM;
1026 
1027                 if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
1028                         err = -EPERM;
1029                 break;
1030         case AUDIT_USER:
1031         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1032         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1033                 if (!netlink_capable(skb, CAP_AUDIT_WRITE))
1034                         err = -EPERM;
1035                 break;
1036         default:  /* bad msg */
1037                 err = -EINVAL;
1038         }
1039 
1040         return err;
1041 }
1042 
1043 static void audit_log_common_recv_msg(struct audit_context *context,
1044                                         struct audit_buffer **ab, u16 msg_type)
1045 {
1046         uid_t uid = from_kuid(&init_user_ns, current_uid());
1047         pid_t pid = task_tgid_nr(current);
1048 
1049         if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
1050                 *ab = NULL;
1051                 return;
1052         }
1053 
1054         *ab = audit_log_start(context, GFP_KERNEL, msg_type);
1055         if (unlikely(!*ab))
1056                 return;
1057         audit_log_format(*ab, "pid=%d uid=%u ", pid, uid);
1058         audit_log_session_info(*ab);
1059         audit_log_task_context(*ab);
1060 }
1061 
1062 static inline void audit_log_user_recv_msg(struct audit_buffer **ab,
1063                                            u16 msg_type)
1064 {
1065         audit_log_common_recv_msg(NULL, ab, msg_type);
1066 }
1067 
1068 int is_audit_feature_set(int i)
1069 {
1070         return af.features & AUDIT_FEATURE_TO_MASK(i);
1071 }
1072 
1073 
1074 static int audit_get_feature(struct sk_buff *skb)
1075 {
1076         u32 seq;
1077 
1078         seq = nlmsg_hdr(skb)->nlmsg_seq;
1079 
1080         audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
1081 
1082         return 0;
1083 }
1084 
1085 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
1086                                      u32 old_lock, u32 new_lock, int res)
1087 {
1088         struct audit_buffer *ab;
1089 
1090         if (audit_enabled == AUDIT_OFF)
1091                 return;
1092 
1093         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
1094         if (!ab)
1095                 return;
1096         audit_log_task_info(ab);
1097         audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
1098                          audit_feature_names[which], !!old_feature, !!new_feature,
1099                          !!old_lock, !!new_lock, res);
1100         audit_log_end(ab);
1101 }
1102 
1103 static int audit_set_feature(struct audit_features *uaf)
1104 {
1105         int i;
1106 
1107         BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
1108 
1109         /* if there is ever a version 2 we should handle that here */
1110 
1111         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1112                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1113                 u32 old_feature, new_feature, old_lock, new_lock;
1114 
1115                 /* if we are not changing this feature, move along */
1116                 if (!(feature & uaf->mask))
1117                         continue;
1118 
1119                 old_feature = af.features & feature;
1120                 new_feature = uaf->features & feature;
1121                 new_lock = (uaf->lock | af.lock) & feature;
1122                 old_lock = af.lock & feature;
1123 
1124                 /* are we changing a locked feature? */
1125                 if (old_lock && (new_feature != old_feature)) {
1126                         audit_log_feature_change(i, old_feature, new_feature,
1127                                                  old_lock, new_lock, 0);
1128                         return -EPERM;
1129                 }
1130         }
1131         /* nothing invalid, do the changes */
1132         for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
1133                 u32 feature = AUDIT_FEATURE_TO_MASK(i);
1134                 u32 old_feature, new_feature, old_lock, new_lock;
1135 
1136                 /* if we are not changing this feature, move along */
1137                 if (!(feature & uaf->mask))
1138                         continue;
1139 
1140                 old_feature = af.features & feature;
1141                 new_feature = uaf->features & feature;
1142                 old_lock = af.lock & feature;
1143                 new_lock = (uaf->lock | af.lock) & feature;
1144 
1145                 if (new_feature != old_feature)
1146                         audit_log_feature_change(i, old_feature, new_feature,
1147                                                  old_lock, new_lock, 1);
1148 
1149                 if (new_feature)
1150                         af.features |= feature;
1151                 else
1152                         af.features &= ~feature;
1153                 af.lock |= new_lock;
1154         }
1155 
1156         return 0;
1157 }
1158 
1159 static int audit_replace(struct pid *pid)
1160 {
1161         pid_t pvnr;
1162         struct sk_buff *skb;
1163 
1164         pvnr = pid_vnr(pid);
1165         skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
1166         if (!skb)
1167                 return -ENOMEM;
1168         return auditd_send_unicast_skb(skb);
1169 }
1170 
1171 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
1172 {
1173         u32                     seq;
1174         void                    *data;
1175         int                     data_len;
1176         int                     err;
1177         struct audit_buffer     *ab;
1178         u16                     msg_type = nlh->nlmsg_type;
1179         struct audit_sig_info   *sig_data;
1180         char                    *ctx = NULL;
1181         u32                     len;
1182 
1183         err = audit_netlink_ok(skb, msg_type);
1184         if (err)
1185                 return err;
1186 
1187         seq  = nlh->nlmsg_seq;
1188         data = nlmsg_data(nlh);
1189         data_len = nlmsg_len(nlh);
1190 
1191         switch (msg_type) {
1192         case AUDIT_GET: {
1193                 struct audit_status     s;
1194                 memset(&s, 0, sizeof(s));
1195                 s.enabled               = audit_enabled;
1196                 s.failure               = audit_failure;
1197                 /* NOTE: use pid_vnr() so the PID is relative to the current
1198                  *       namespace */
1199                 s.pid                   = auditd_pid_vnr();
1200                 s.rate_limit            = audit_rate_limit;
1201                 s.backlog_limit         = audit_backlog_limit;
1202                 s.lost                  = atomic_read(&audit_lost);
1203                 s.backlog               = skb_queue_len(&audit_queue);
1204                 s.feature_bitmap        = AUDIT_FEATURE_BITMAP_ALL;
1205                 s.backlog_wait_time     = audit_backlog_wait_time;
1206                 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
1207                 break;
1208         }
1209         case AUDIT_SET: {
1210                 struct audit_status     s;
1211                 memset(&s, 0, sizeof(s));
1212                 /* guard against past and future API changes */
1213                 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1214                 if (s.mask & AUDIT_STATUS_ENABLED) {
1215                         err = audit_set_enabled(s.enabled);
1216                         if (err < 0)
1217                                 return err;
1218                 }
1219                 if (s.mask & AUDIT_STATUS_FAILURE) {
1220                         err = audit_set_failure(s.failure);
1221                         if (err < 0)
1222                                 return err;
1223                 }
1224                 if (s.mask & AUDIT_STATUS_PID) {
1225                         /* NOTE: we are using the vnr PID functions below
1226                          *       because the s.pid value is relative to the
1227                          *       namespace of the caller; at present this
1228                          *       doesn't matter much since you can really only
1229                          *       run auditd from the initial pid namespace, but
1230                          *       something to keep in mind if this changes */
1231                         pid_t new_pid = s.pid;
1232                         pid_t auditd_pid;
1233                         struct pid *req_pid = task_tgid(current);
1234 
1235                         /* Sanity check - PID values must match. Setting
1236                          * pid to 0 is how auditd ends auditing. */
1237                         if (new_pid && (new_pid != pid_vnr(req_pid)))
1238                                 return -EINVAL;
1239 
1240                         /* test the auditd connection */
1241                         audit_replace(req_pid);
1242 
1243                         auditd_pid = auditd_pid_vnr();
1244                         if (auditd_pid) {
1245                                 /* replacing a healthy auditd is not allowed */
1246                                 if (new_pid) {
1247                                         audit_log_config_change("audit_pid",
1248                                                         new_pid, auditd_pid, 0);
1249                                         return -EEXIST;
1250                                 }
1251                                 /* only current auditd can unregister itself */
1252                                 if (pid_vnr(req_pid) != auditd_pid) {
1253                                         audit_log_config_change("audit_pid",
1254                                                         new_pid, auditd_pid, 0);
1255                                         return -EACCES;
1256                                 }
1257                         }
1258 
1259                         if (new_pid) {
1260                                 /* register a new auditd connection */
1261                                 err = auditd_set(req_pid,
1262                                                  NETLINK_CB(skb).portid,
1263                                                  sock_net(NETLINK_CB(skb).sk));
1264                                 if (audit_enabled != AUDIT_OFF)
1265                                         audit_log_config_change("audit_pid",
1266                                                                 new_pid,
1267                                                                 auditd_pid,
1268                                                                 err ? 0 : 1);
1269                                 if (err)
1270                                         return err;
1271 
1272                                 /* try to process any backlog */
1273                                 wake_up_interruptible(&kauditd_wait);
1274                         } else {
1275                                 if (audit_enabled != AUDIT_OFF)
1276                                         audit_log_config_change("audit_pid",
1277                                                                 new_pid,
1278                                                                 auditd_pid, 1);
1279 
1280                                 /* unregister the auditd connection */
1281                                 auditd_reset(NULL);
1282                         }
1283                 }
1284                 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
1285                         err = audit_set_rate_limit(s.rate_limit);
1286                         if (err < 0)
1287                                 return err;
1288                 }
1289                 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
1290                         err = audit_set_backlog_limit(s.backlog_limit);
1291                         if (err < 0)
1292                                 return err;
1293                 }
1294                 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
1295                         if (sizeof(s) > (size_t)nlh->nlmsg_len)
1296                                 return -EINVAL;
1297                         if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
1298                                 return -EINVAL;
1299                         err = audit_set_backlog_wait_time(s.backlog_wait_time);
1300                         if (err < 0)
1301                                 return err;
1302                 }
1303                 if (s.mask == AUDIT_STATUS_LOST) {
1304                         u32 lost = atomic_xchg(&audit_lost, 0);
1305 
1306                         audit_log_config_change("lost", 0, lost, 1);
1307                         return lost;
1308                 }
1309                 break;
1310         }
1311         case AUDIT_GET_FEATURE:
1312                 err = audit_get_feature(skb);
1313                 if (err)
1314                         return err;
1315                 break;
1316         case AUDIT_SET_FEATURE:
1317                 if (data_len < sizeof(struct audit_features))
1318                         return -EINVAL;
1319                 err = audit_set_feature(data);
1320                 if (err)
1321                         return err;
1322                 break;
1323         case AUDIT_USER:
1324         case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
1325         case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
1326                 if (!audit_enabled && msg_type != AUDIT_USER_AVC)
1327                         return 0;
1328                 /* exit early if there isn't at least one character to print */
1329                 if (data_len < 2)
1330                         return -EINVAL;
1331 
1332                 err = audit_filter(msg_type, AUDIT_FILTER_USER);
1333                 if (err == 1) { /* match or error */
1334                         char *str = data;
1335 
1336                         err = 0;
1337                         if (msg_type == AUDIT_USER_TTY) {
1338                                 err = tty_audit_push();
1339                                 if (err)
1340                                         break;
1341                         }
1342                         audit_log_user_recv_msg(&ab, msg_type);
1343                         if (msg_type != AUDIT_USER_TTY) {
1344                                 /* ensure NULL termination */
1345                                 str[data_len - 1] = '\0';
1346                                 audit_log_format(ab, " msg='%.*s'",
1347                                                  AUDIT_MESSAGE_TEXT_MAX,
1348                                                  str);
1349                         } else {
1350                                 audit_log_format(ab, " data=");
1351                                 if (data_len > 0 && str[data_len - 1] == '\0')
1352                                         data_len--;
1353                                 audit_log_n_untrustedstring(ab, str, data_len);
1354                         }
1355                         audit_log_end(ab);
1356                 }
1357                 break;
1358         case AUDIT_ADD_RULE:
1359         case AUDIT_DEL_RULE:
1360                 if (data_len < sizeof(struct audit_rule_data))
1361                         return -EINVAL;
1362                 if (audit_enabled == AUDIT_LOCKED) {
1363                         audit_log_common_recv_msg(audit_context(), &ab,
1364                                                   AUDIT_CONFIG_CHANGE);
1365                         audit_log_format(ab, " op=%s audit_enabled=%d res=0",
1366                                          msg_type == AUDIT_ADD_RULE ?
1367                                                 "add_rule" : "remove_rule",
1368                                          audit_enabled);
1369                         audit_log_end(ab);
1370                         return -EPERM;
1371                 }
1372                 err = audit_rule_change(msg_type, seq, data, data_len);
1373                 break;
1374         case AUDIT_LIST_RULES:
1375                 err = audit_list_rules_send(skb, seq);
1376                 break;
1377         case AUDIT_TRIM:
1378                 audit_trim_trees();
1379                 audit_log_common_recv_msg(audit_context(), &ab,
1380                                           AUDIT_CONFIG_CHANGE);
1381                 audit_log_format(ab, " op=trim res=1");
1382                 audit_log_end(ab);
1383                 break;
1384         case AUDIT_MAKE_EQUIV: {
1385                 void *bufp = data;
1386                 u32 sizes[2];
1387                 size_t msglen = data_len;
1388                 char *old, *new;
1389 
1390                 err = -EINVAL;
1391                 if (msglen < 2 * sizeof(u32))
1392                         break;
1393                 memcpy(sizes, bufp, 2 * sizeof(u32));
1394                 bufp += 2 * sizeof(u32);
1395                 msglen -= 2 * sizeof(u32);
1396                 old = audit_unpack_string(&bufp, &msglen, sizes[0]);
1397                 if (IS_ERR(old)) {
1398                         err = PTR_ERR(old);
1399                         break;
1400                 }
1401                 new = audit_unpack_string(&bufp, &msglen, sizes[1]);
1402                 if (IS_ERR(new)) {
1403                         err = PTR_ERR(new);
1404                         kfree(old);
1405                         break;
1406                 }
1407                 /* OK, here comes... */
1408                 err = audit_tag_tree(old, new);
1409 
1410                 audit_log_common_recv_msg(audit_context(), &ab,
1411                                           AUDIT_CONFIG_CHANGE);
1412                 audit_log_format(ab, " op=make_equiv old=");
1413                 audit_log_untrustedstring(ab, old);
1414                 audit_log_format(ab, " new=");
1415                 audit_log_untrustedstring(ab, new);
1416                 audit_log_format(ab, " res=%d", !err);
1417                 audit_log_end(ab);
1418                 kfree(old);
1419                 kfree(new);
1420                 break;
1421         }
1422         case AUDIT_SIGNAL_INFO:
1423                 len = 0;
1424                 if (audit_sig_sid) {
1425                         err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
1426                         if (err)
1427                                 return err;
1428                 }
1429                 sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
1430                 if (!sig_data) {
1431                         if (audit_sig_sid)
1432                                 security_release_secctx(ctx, len);
1433                         return -ENOMEM;
1434                 }
1435                 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
1436                 sig_data->pid = audit_sig_pid;
1437                 if (audit_sig_sid) {
1438                         memcpy(sig_data->ctx, ctx, len);
1439                         security_release_secctx(ctx, len);
1440                 }
1441                 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1442                                  sig_data, sizeof(*sig_data) + len);
1443                 kfree(sig_data);
1444                 break;
1445         case AUDIT_TTY_GET: {
1446                 struct audit_tty_status s;
1447                 unsigned int t;
1448 
1449                 t = READ_ONCE(current->signal->audit_tty);
1450                 s.enabled = t & AUDIT_TTY_ENABLE;
1451                 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1452 
1453                 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1454                 break;
1455         }
1456         case AUDIT_TTY_SET: {
1457                 struct audit_tty_status s, old;
1458                 struct audit_buffer     *ab;
1459                 unsigned int t;
1460 
1461                 memset(&s, 0, sizeof(s));
1462                 /* guard against past and future API changes */
1463                 memcpy(&s, data, min_t(size_t, sizeof(s), data_len));
1464                 /* check if new data is valid */
1465                 if ((s.enabled != 0 && s.enabled != 1) ||
1466                     (s.log_passwd != 0 && s.log_passwd != 1))
1467                         err = -EINVAL;
1468 
1469                 if (err)
1470                         t = READ_ONCE(current->signal->audit_tty);
1471                 else {
1472                         t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
1473                         t = xchg(&current->signal->audit_tty, t);
1474                 }
1475                 old.enabled = t & AUDIT_TTY_ENABLE;
1476                 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
1477 
1478                 audit_log_common_recv_msg(audit_context(), &ab,
1479                                           AUDIT_CONFIG_CHANGE);
1480                 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1481                                  " old-log_passwd=%d new-log_passwd=%d res=%d",
1482                                  old.enabled, s.enabled, old.log_passwd,
1483                                  s.log_passwd, !err);
1484                 audit_log_end(ab);
1485                 break;
1486         }
1487         default:
1488                 err = -EINVAL;
1489                 break;
1490         }
1491 
1492         return err < 0 ? err : 0;
1493 }
1494 
1495 /**
1496  * audit_receive - receive messages from a netlink control socket
1497  * @skb: the message buffer
1498  *
1499  * Parse the provided skb and deal with any messages that may be present,
1500  * malformed skbs are discarded.
1501  */
1502 static void audit_receive(struct sk_buff  *skb)
1503 {
1504         struct nlmsghdr *nlh;
1505         /*
1506          * len MUST be signed for nlmsg_next to be able to dec it below 0
1507          * if the nlmsg_len was not aligned
1508          */
1509         int len;
1510         int err;
1511 
1512         nlh = nlmsg_hdr(skb);
1513         len = skb->len;
1514 
1515         audit_ctl_lock();
1516         while (nlmsg_ok(nlh, len)) {
1517                 err = audit_receive_msg(skb, nlh);
1518                 /* if err or if this message says it wants a response */
1519                 if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1520                         netlink_ack(skb, nlh, err, NULL);
1521 
1522                 nlh = nlmsg_next(nlh, &len);
1523         }
1524         audit_ctl_unlock();
1525 }
1526 
1527 /* Run custom bind function on netlink socket group connect or bind requests. */
1528 static int audit_bind(struct net *net, int group)
1529 {
1530         if (!capable(CAP_AUDIT_READ))
1531                 return -EPERM;
1532 
1533         return 0;
1534 }
1535 
1536 static int __net_init audit_net_init(struct net *net)
1537 {
1538         struct netlink_kernel_cfg cfg = {
1539                 .input  = audit_receive,
1540                 .bind   = audit_bind,
1541                 .flags  = NL_CFG_F_NONROOT_RECV,
1542                 .groups = AUDIT_NLGRP_MAX,
1543         };
1544 
1545         struct audit_net *aunet = net_generic(net, audit_net_id);
1546 
1547         aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1548         if (aunet->sk == NULL) {
1549                 audit_panic("cannot initialize netlink socket in namespace");
1550                 return -ENOMEM;
1551         }
1552         aunet->sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1553 
1554         return 0;
1555 }
1556 
1557 static void __net_exit audit_net_exit(struct net *net)
1558 {
1559         struct audit_net *aunet = net_generic(net, audit_net_id);
1560 
1561         /* NOTE: you would think that we would want to check the auditd
1562          * connection and potentially reset it here if it lives in this
1563          * namespace, but since the auditd connection tracking struct holds a
1564          * reference to this namespace (see auditd_set()) we are only ever
1565          * going to get here after that connection has been released */
1566 
1567         netlink_kernel_release(aunet->sk);
1568 }
1569 
1570 static struct pernet_operations audit_net_ops __net_initdata = {
1571         .init = audit_net_init,
1572         .exit = audit_net_exit,
1573         .id = &audit_net_id,
1574         .size = sizeof(struct audit_net),
1575 };
1576 
1577 /* Initialize audit support at boot time. */
1578 static int __init audit_init(void)
1579 {
1580         int i;
1581 
1582         if (audit_initialized == AUDIT_DISABLED)
1583                 return 0;
1584 
1585         audit_buffer_cache = kmem_cache_create("audit_buffer",
1586                                                sizeof(struct audit_buffer),
1587                                                0, SLAB_PANIC, NULL);
1588 
1589         skb_queue_head_init(&audit_queue);
1590         skb_queue_head_init(&audit_retry_queue);
1591         skb_queue_head_init(&audit_hold_queue);
1592 
1593         for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1594                 INIT_LIST_HEAD(&audit_inode_hash[i]);
1595 
1596         mutex_init(&audit_cmd_mutex.lock);
1597         audit_cmd_mutex.owner = NULL;
1598 
1599         pr_info("initializing netlink subsys (%s)\n",
1600                 audit_default ? "enabled" : "disabled");
1601         register_pernet_subsys(&audit_net_ops);
1602 
1603         audit_initialized = AUDIT_INITIALIZED;
1604 
1605         kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
1606         if (IS_ERR(kauditd_task)) {
1607                 int err = PTR_ERR(kauditd_task);
1608                 panic("audit: failed to start the kauditd thread (%d)\n", err);
1609         }
1610 
1611         audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL,
1612                 "state=initialized audit_enabled=%u res=1",
1613                  audit_enabled);
1614 
1615         return 0;
1616 }
1617 postcore_initcall(audit_init);
1618 
1619 /*
1620  * Process kernel command-line parameter at boot time.
1621  * audit={0|off} or audit={1|on}.
1622  */
1623 static int __init audit_enable(char *str)
1624 {
1625         if (!strcasecmp(str, "off") || !strcmp(str, "0"))
1626                 audit_default = AUDIT_OFF;
1627         else if (!strcasecmp(str, "on") || !strcmp(str, "1"))
1628                 audit_default = AUDIT_ON;
1629         else {
1630                 pr_err("audit: invalid 'audit' parameter value (%s)\n", str);
1631                 audit_default = AUDIT_ON;
1632         }
1633 
1634         if (audit_default == AUDIT_OFF)
1635                 audit_initialized = AUDIT_DISABLED;
1636         if (audit_set_enabled(audit_default))
1637                 pr_err("audit: error setting audit state (%d)\n",
1638                        audit_default);
1639 
1640         pr_info("%s\n", audit_default ?
1641                 "enabled (after initialization)" : "disabled (until reboot)");
1642 
1643         return 1;
1644 }
1645 __setup("audit=", audit_enable);
1646 
1647 /* Process kernel command-line parameter at boot time.
1648  * audit_backlog_limit=<n> */
1649 static int __init audit_backlog_limit_set(char *str)
1650 {
1651         u32 audit_backlog_limit_arg;
1652 
1653         pr_info("audit_backlog_limit: ");
1654         if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1655                 pr_cont("using default of %u, unable to parse %s\n",
1656                         audit_backlog_limit, str);
1657                 return 1;
1658         }
1659 
1660         audit_backlog_limit = audit_backlog_limit_arg;
1661         pr_cont("%d\n", audit_backlog_limit);
1662 
1663         return 1;
1664 }
1665 __setup("audit_backlog_limit=", audit_backlog_limit_set);
1666 
1667 static void audit_buffer_free(struct audit_buffer *ab)
1668 {
1669         if (!ab)
1670                 return;
1671 
1672         kfree_skb(ab->skb);
1673         kmem_cache_free(audit_buffer_cache, ab);
1674 }
1675 
1676 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx,
1677                                                gfp_t gfp_mask, int type)
1678 {
1679         struct audit_buffer *ab;
1680 
1681         ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask);
1682         if (!ab)
1683                 return NULL;
1684 
1685         ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1686         if (!ab->skb)
1687                 goto err;
1688         if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0))
1689                 goto err;
1690 
1691         ab->ctx = ctx;
1692         ab->gfp_mask = gfp_mask;
1693 
1694         return ab;
1695 
1696 err:
1697         audit_buffer_free(ab);
1698         return NULL;
1699 }
1700 
1701 /**
1702  * audit_serial - compute a serial number for the audit record
1703  *
1704  * Compute a serial number for the audit record.  Audit records are
1705  * written to user-space as soon as they are generated, so a complete
1706  * audit record may be written in several pieces.  The timestamp of the
1707  * record and this serial number are used by the user-space tools to
1708  * determine which pieces belong to the same audit record.  The
1709  * (timestamp,serial) tuple is unique for each syscall and is live from
1710  * syscall entry to syscall exit.
1711  *
1712  * NOTE: Another possibility is to store the formatted records off the
1713  * audit context (for those records that have a context), and emit them
1714  * all at syscall exit.  However, this could delay the reporting of
1715  * significant errors until syscall exit (or never, if the system
1716  * halts).
1717  */
1718 unsigned int audit_serial(void)
1719 {
1720         static atomic_t serial = ATOMIC_INIT(0);
1721 
1722         return atomic_add_return(1, &serial);
1723 }
1724 
1725 static inline void audit_get_stamp(struct audit_context *ctx,
1726                                    struct timespec64 *t, unsigned int *serial)
1727 {
1728         if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1729                 ktime_get_coarse_real_ts64(t);
1730                 *serial = audit_serial();
1731         }
1732 }
1733 
1734 /**
1735  * audit_log_start - obtain an audit buffer
1736  * @ctx: audit_context (may be NULL)
1737  * @gfp_mask: type of allocation
1738  * @type: audit message type
1739  *
1740  * Returns audit_buffer pointer on success or NULL on error.
1741  *
1742  * Obtain an audit buffer.  This routine does locking to obtain the
1743  * audit buffer, but then no locking is required for calls to
1744  * audit_log_*format.  If the task (ctx) is a task that is currently in a
1745  * syscall, then the syscall is marked as auditable and an audit record
1746  * will be written at syscall exit.  If there is no associated task, then
1747  * task context (ctx) should be NULL.
1748  */
1749 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1750                                      int type)
1751 {
1752         struct audit_buffer *ab;
1753         struct timespec64 t;
1754         unsigned int uninitialized_var(serial);
1755 
1756         if (audit_initialized != AUDIT_INITIALIZED)
1757                 return NULL;
1758 
1759         if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE)))
1760                 return NULL;
1761 
1762         /* NOTE: don't ever fail/sleep on these two conditions:
1763          * 1. auditd generated record - since we need auditd to drain the
1764          *    queue; also, when we are checking for auditd, compare PIDs using
1765          *    task_tgid_vnr() since auditd_pid is set in audit_receive_msg()
1766          *    using a PID anchored in the caller's namespace
1767          * 2. generator holding the audit_cmd_mutex - we don't want to block
1768          *    while holding the mutex */
1769         if (!(auditd_test_task(current) || audit_ctl_owner_current())) {
1770                 long stime = audit_backlog_wait_time;
1771 
1772                 while (audit_backlog_limit &&
1773                        (skb_queue_len(&audit_queue) > audit_backlog_limit)) {
1774                         /* wake kauditd to try and flush the queue */
1775                         wake_up_interruptible(&kauditd_wait);
1776 
1777                         /* sleep if we are allowed and we haven't exhausted our
1778                          * backlog wait limit */
1779                         if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) {
1780                                 DECLARE_WAITQUEUE(wait, current);
1781 
1782                                 add_wait_queue_exclusive(&audit_backlog_wait,
1783                                                          &wait);
1784                                 set_current_state(TASK_UNINTERRUPTIBLE);
1785                                 stime = schedule_timeout(stime);
1786                                 remove_wait_queue(&audit_backlog_wait, &wait);
1787                         } else {
1788                                 if (audit_rate_check() && printk_ratelimit())
1789                                         pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1790                                                 skb_queue_len(&audit_queue),
1791                                                 audit_backlog_limit);
1792                                 audit_log_lost("backlog limit exceeded");
1793                                 return NULL;
1794                         }
1795                 }
1796         }
1797 
1798         ab = audit_buffer_alloc(ctx, gfp_mask, type);
1799         if (!ab) {
1800                 audit_log_lost("out of memory in audit_log_start");
1801                 return NULL;
1802         }
1803 
1804         audit_get_stamp(ab->ctx, &t, &serial);
1805         audit_log_format(ab, "audit(%llu.%03lu:%u): ",
1806                          (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
1807 
1808         return ab;
1809 }
1810 
1811 /**
1812  * audit_expand - expand skb in the audit buffer
1813  * @ab: audit_buffer
1814  * @extra: space to add at tail of the skb
1815  *
1816  * Returns 0 (no space) on failed expansion, or available space if
1817  * successful.
1818  */
1819 static inline int audit_expand(struct audit_buffer *ab, int extra)
1820 {
1821         struct sk_buff *skb = ab->skb;
1822         int oldtail = skb_tailroom(skb);
1823         int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1824         int newtail = skb_tailroom(skb);
1825 
1826         if (ret < 0) {
1827                 audit_log_lost("out of memory in audit_expand");
1828                 return 0;
1829         }
1830 
1831         skb->truesize += newtail - oldtail;
1832         return newtail;
1833 }
1834 
1835 /*
1836  * Format an audit message into the audit buffer.  If there isn't enough
1837  * room in the audit buffer, more room will be allocated and vsnprint
1838  * will be called a second time.  Currently, we assume that a printk
1839  * can't format message larger than 1024 bytes, so we don't either.
1840  */
1841 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1842                               va_list args)
1843 {
1844         int len, avail;
1845         struct sk_buff *skb;
1846         va_list args2;
1847 
1848         if (!ab)
1849                 return;
1850 
1851         BUG_ON(!ab->skb);
1852         skb = ab->skb;
1853         avail = skb_tailroom(skb);
1854         if (avail == 0) {
1855                 avail = audit_expand(ab, AUDIT_BUFSIZ);
1856                 if (!avail)
1857                         goto out;
1858         }
1859         va_copy(args2, args);
1860         len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1861         if (len >= avail) {
1862                 /* The printk buffer is 1024 bytes long, so if we get
1863                  * here and AUDIT_BUFSIZ is at least 1024, then we can
1864                  * log everything that printk could have logged. */
1865                 avail = audit_expand(ab,
1866                         max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1867                 if (!avail)
1868                         goto out_va_end;
1869                 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1870         }
1871         if (len > 0)
1872                 skb_put(skb, len);
1873 out_va_end:
1874         va_end(args2);
1875 out:
1876         return;
1877 }
1878 
1879 /**
1880  * audit_log_format - format a message into the audit buffer.
1881  * @ab: audit_buffer
1882  * @fmt: format string
1883  * @...: optional parameters matching @fmt string
1884  *
1885  * All the work is done in audit_log_vformat.
1886  */
1887 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1888 {
1889         va_list args;
1890 
1891         if (!ab)
1892                 return;
1893         va_start(args, fmt);
1894         audit_log_vformat(ab, fmt, args);
1895         va_end(args);
1896 }
1897 
1898 /**
1899  * audit_log_n_hex - convert a buffer to hex and append it to the audit skb
1900  * @ab: the audit_buffer
1901  * @buf: buffer to convert to hex
1902  * @len: length of @buf to be converted
1903  *
1904  * No return value; failure to expand is silently ignored.
1905  *
1906  * This function will take the passed buf and convert it into a string of
1907  * ascii hex digits. The new string is placed onto the skb.
1908  */
1909 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1910                 size_t len)
1911 {
1912         int i, avail, new_len;
1913         unsigned char *ptr;
1914         struct sk_buff *skb;
1915 
1916         if (!ab)
1917                 return;
1918 
1919         BUG_ON(!ab->skb);
1920         skb = ab->skb;
1921         avail = skb_tailroom(skb);
1922         new_len = len<<1;
1923         if (new_len >= avail) {
1924                 /* Round the buffer request up to the next multiple */
1925                 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1926                 avail = audit_expand(ab, new_len);
1927                 if (!avail)
1928                         return;
1929         }
1930 
1931         ptr = skb_tail_pointer(skb);
1932         for (i = 0; i < len; i++)
1933                 ptr = hex_byte_pack_upper(ptr, buf[i]);
1934         *ptr = 0;
1935         skb_put(skb, len << 1); /* new string is twice the old string */
1936 }
1937 
1938 /*
1939  * Format a string of no more than slen characters into the audit buffer,
1940  * enclosed in quote marks.
1941  */
1942 void audit_log_n_string(struct audit_buffer *ab, const char *string,
1943                         size_t slen)
1944 {
1945         int avail, new_len;
1946         unsigned char *ptr;
1947         struct sk_buff *skb;
1948 
1949         if (!ab)
1950                 return;
1951 
1952         BUG_ON(!ab->skb);
1953         skb = ab->skb;
1954         avail = skb_tailroom(skb);
1955         new_len = slen + 3;     /* enclosing quotes + null terminator */
1956         if (new_len > avail) {
1957                 avail = audit_expand(ab, new_len);
1958                 if (!avail)
1959                         return;
1960         }
1961         ptr = skb_tail_pointer(skb);
1962         *ptr++ = '"';
1963         memcpy(ptr, string, slen);
1964         ptr += slen;
1965         *ptr++ = '"';
1966         *ptr = 0;
1967         skb_put(skb, slen + 2); /* don't include null terminator */
1968 }
1969 
1970 /**
1971  * audit_string_contains_control - does a string need to be logged in hex
1972  * @string: string to be checked
1973  * @len: max length of the string to check
1974  */
1975 bool audit_string_contains_control(const char *string, size_t len)
1976 {
1977         const unsigned char *p;
1978         for (p = string; p < (const unsigned char *)string + len; p++) {
1979                 if (*p == '"' || *p < 0x21 || *p > 0x7e)
1980                         return true;
1981         }
1982         return false;
1983 }
1984 
1985 /**
1986  * audit_log_n_untrustedstring - log a string that may contain random characters
1987  * @ab: audit_buffer
1988  * @len: length of string (not including trailing null)
1989  * @string: string to be logged
1990  *
1991  * This code will escape a string that is passed to it if the string
1992  * contains a control character, unprintable character, double quote mark,
1993  * or a space. Unescaped strings will start and end with a double quote mark.
1994  * Strings that are escaped are printed in hex (2 digits per char).
1995  *
1996  * The caller specifies the number of characters in the string to log, which may
1997  * or may not be the entire string.
1998  */
1999 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
2000                                  size_t len)
2001 {
2002         if (audit_string_contains_control(string, len))
2003                 audit_log_n_hex(ab, string, len);
2004         else
2005                 audit_log_n_string(ab, string, len);
2006 }
2007 
2008 /**
2009  * audit_log_untrustedstring - log a string that may contain random characters
2010  * @ab: audit_buffer
2011  * @string: string to be logged
2012  *
2013  * Same as audit_log_n_untrustedstring(), except that strlen is used to
2014  * determine string length.
2015  */
2016 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
2017 {
2018         audit_log_n_untrustedstring(ab, string, strlen(string));
2019 }
2020 
2021 /* This is a helper-function to print the escaped d_path */
2022 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
2023                       const struct path *path)
2024 {
2025         char *p, *pathname;
2026 
2027         if (prefix)
2028                 audit_log_format(ab, "%s", prefix);
2029 
2030         /* We will allow 11 spaces for ' (deleted)' to be appended */
2031         pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
2032         if (!pathname) {
2033                 audit_log_string(ab, "<no_memory>");
2034                 return;
2035         }
2036         p = d_path(path, pathname, PATH_MAX+11);
2037         if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
2038                 /* FIXME: can we save some information here? */
2039                 audit_log_string(ab, "<too_long>");
2040         } else
2041                 audit_log_untrustedstring(ab, p);
2042         kfree(pathname);
2043 }
2044 
2045 void audit_log_session_info(struct audit_buffer *ab)
2046 {
2047         unsigned int sessionid = audit_get_sessionid(current);
2048         uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
2049 
2050         audit_log_format(ab, "auid=%u ses=%u", auid, sessionid);
2051 }
2052 
2053 void audit_log_key(struct audit_buffer *ab, char *key)
2054 {
2055         audit_log_format(ab, " key=");
2056         if (key)
2057                 audit_log_untrustedstring(ab, key);
2058         else
2059                 audit_log_format(ab, "(null)");
2060 }
2061 
2062 int audit_log_task_context(struct audit_buffer *ab)
2063 {
2064         char *ctx = NULL;
2065         unsigned len;
2066         int error;
2067         u32 sid;
2068 
2069         security_task_getsecid(current, &sid);
2070         if (!sid)
2071                 return 0;
2072 
2073         error = security_secid_to_secctx(sid, &ctx, &len);
2074         if (error) {
2075                 if (error != -EINVAL)
2076                         goto error_path;
2077                 return 0;
2078         }
2079 
2080         audit_log_format(ab, " subj=%s", ctx);
2081         security_release_secctx(ctx, len);
2082         return 0;
2083 
2084 error_path:
2085         audit_panic("error in audit_log_task_context");
2086         return error;
2087 }
2088 EXPORT_SYMBOL(audit_log_task_context);
2089 
2090 void audit_log_d_path_exe(struct audit_buffer *ab,
2091                           struct mm_struct *mm)
2092 {
2093         struct file *exe_file;
2094 
2095         if (!mm)
2096                 goto out_null;
2097 
2098         exe_file = get_mm_exe_file(mm);
2099         if (!exe_file)
2100                 goto out_null;
2101 
2102         audit_log_d_path(ab, " exe=", &exe_file->f_path);
2103         fput(exe_file);
2104         return;
2105 out_null:
2106         audit_log_format(ab, " exe=(null)");
2107 }
2108 
2109 struct tty_struct *audit_get_tty(void)
2110 {
2111         struct tty_struct *tty = NULL;
2112         unsigned long flags;
2113 
2114         spin_lock_irqsave(&current->sighand->siglock, flags);
2115         if (current->signal)
2116                 tty = tty_kref_get(current->signal->tty);
2117         spin_unlock_irqrestore(&current->sighand->siglock, flags);
2118         return tty;
2119 }
2120 
2121 void audit_put_tty(struct tty_struct *tty)
2122 {
2123         tty_kref_put(tty);
2124 }
2125 
2126 void audit_log_task_info(struct audit_buffer *ab)
2127 {
2128         const struct cred *cred;
2129         char comm[sizeof(current->comm)];
2130         struct tty_struct *tty;
2131 
2132         if (!ab)
2133                 return;
2134 
2135         cred = current_cred();
2136         tty = audit_get_tty();
2137         audit_log_format(ab,
2138                          " ppid=%d pid=%d auid=%u uid=%u gid=%u"
2139                          " euid=%u suid=%u fsuid=%u"
2140                          " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
2141                          task_ppid_nr(current),
2142                          task_tgid_nr(current),
2143                          from_kuid(&init_user_ns, audit_get_loginuid(current)),
2144                          from_kuid(&init_user_ns, cred->uid),
2145                          from_kgid(&init_user_ns, cred->gid),
2146                          from_kuid(&init_user_ns, cred->euid),
2147                          from_kuid(&init_user_ns, cred->suid),
2148                          from_kuid(&init_user_ns, cred->fsuid),
2149                          from_kgid(&init_user_ns, cred->egid),
2150                          from_kgid(&init_user_ns, cred->sgid),
2151                          from_kgid(&init_user_ns, cred->fsgid),
2152                          tty ? tty_name(tty) : "(none)",
2153                          audit_get_sessionid(current));
2154         audit_put_tty(tty);
2155         audit_log_format(ab, " comm=");
2156         audit_log_untrustedstring(ab, get_task_comm(comm, current));
2157         audit_log_d_path_exe(ab, current->mm);
2158         audit_log_task_context(ab);
2159 }
2160 EXPORT_SYMBOL(audit_log_task_info);
2161 
2162 /**
2163  * audit_log_link_denied - report a link restriction denial
2164  * @operation: specific link operation
2165  */
2166 void audit_log_link_denied(const char *operation)
2167 {
2168         struct audit_buffer *ab;
2169 
2170         if (!audit_enabled || audit_dummy_context())
2171                 return;
2172 
2173         /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
2174         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_ANOM_LINK);
2175         if (!ab)
2176                 return;
2177         audit_log_format(ab, "op=%s", operation);
2178         audit_log_task_info(ab);
2179         audit_log_format(ab, " res=0");
2180         audit_log_end(ab);
2181 }
2182 
2183 /* global counter which is incremented every time something logs in */
2184 static atomic_t session_id = ATOMIC_INIT(0);
2185 
2186 static int audit_set_loginuid_perm(kuid_t loginuid)
2187 {
2188         /* if we are unset, we don't need privs */
2189         if (!audit_loginuid_set(current))
2190                 return 0;
2191         /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/
2192         if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE))
2193                 return -EPERM;
2194         /* it is set, you need permission */
2195         if (!capable(CAP_AUDIT_CONTROL))
2196                 return -EPERM;
2197         /* reject if this is not an unset and we don't allow that */
2198         if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID)
2199                                  && uid_valid(loginuid))
2200                 return -EPERM;
2201         return 0;
2202 }
2203 
2204 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
2205                                    unsigned int oldsessionid,
2206                                    unsigned int sessionid, int rc)
2207 {
2208         struct audit_buffer *ab;
2209         uid_t uid, oldloginuid, loginuid;
2210         struct tty_struct *tty;
2211 
2212         if (!audit_enabled)
2213                 return;
2214 
2215         ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN);
2216         if (!ab)
2217                 return;
2218 
2219         uid = from_kuid(&init_user_ns, task_uid(current));
2220         oldloginuid = from_kuid(&init_user_ns, koldloginuid);
2221         loginuid = from_kuid(&init_user_ns, kloginuid),
2222         tty = audit_get_tty();
2223 
2224         audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
2225         audit_log_task_context(ab);
2226         audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
2227                          oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
2228                          oldsessionid, sessionid, !rc);
2229         audit_put_tty(tty);
2230         audit_log_end(ab);
2231 }
2232 
2233 /**
2234  * audit_set_loginuid - set current task's loginuid
2235  * @loginuid: loginuid value
2236  *
2237  * Returns 0.
2238  *
2239  * Called (set) from fs/proc/base.c::proc_loginuid_write().
2240  */
2241 int audit_set_loginuid(kuid_t loginuid)
2242 {
2243         unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
2244         kuid_t oldloginuid;
2245         int rc;
2246 
2247         oldloginuid = audit_get_loginuid(current);
2248         oldsessionid = audit_get_sessionid(current);
2249 
2250         rc = audit_set_loginuid_perm(loginuid);
2251         if (rc)
2252                 goto out;
2253 
2254         /* are we setting or clearing? */
2255         if (uid_valid(loginuid)) {
2256                 sessionid = (unsigned int)atomic_inc_return(&session_id);
2257                 if (unlikely(sessionid == AUDIT_SID_UNSET))
2258                         sessionid = (unsigned int)atomic_inc_return(&session_id);
2259         }
2260 
2261         current->sessionid = sessionid;
2262         current->loginuid = loginuid;
2263 out:
2264         audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
2265         return rc;
2266 }
2267 
2268 /**
2269  * audit_signal_info - record signal info for shutting down audit subsystem
2270  * @sig: signal value
2271  * @t: task being signaled
2272  *
2273  * If the audit subsystem is being terminated, record the task (pid)
2274  * and uid that is doing that.
2275  */
2276 int audit_signal_info(int sig, struct task_struct *t)
2277 {
2278         kuid_t uid = current_uid(), auid;
2279 
2280         if (auditd_test_task(t) &&
2281             (sig == SIGTERM || sig == SIGHUP ||
2282              sig == SIGUSR1 || sig == SIGUSR2)) {
2283                 audit_sig_pid = task_tgid_nr(current);
2284                 auid = audit_get_loginuid(current);
2285                 if (uid_valid(auid))
2286                         audit_sig_uid = auid;
2287                 else
2288                         audit_sig_uid = uid;
2289                 security_task_getsecid(current, &audit_sig_sid);
2290         }
2291 
2292         return audit_signal_info_syscall(t);
2293 }
2294 
2295 /**
2296  * audit_log_end - end one audit record
2297  * @ab: the audit_buffer
2298  *
2299  * We can not do a netlink send inside an irq context because it blocks (last
2300  * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a
2301  * queue and a tasklet is scheduled to remove them from the queue outside the
2302  * irq context.  May be called in any context.
2303  */
2304 void audit_log_end(struct audit_buffer *ab)
2305 {
2306         struct sk_buff *skb;
2307         struct nlmsghdr *nlh;
2308 
2309         if (!ab)
2310                 return;
2311 
2312         if (audit_rate_check()) {
2313                 skb = ab->skb;
2314                 ab->skb = NULL;
2315 
2316                 /* setup the netlink header, see the comments in
2317                  * kauditd_send_multicast_skb() for length quirks */
2318                 nlh = nlmsg_hdr(skb);
2319                 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN;
2320 
2321                 /* queue the netlink packet and poke the kauditd thread */
2322                 skb_queue_tail(&audit_queue, skb);
2323                 wake_up_interruptible(&kauditd_wait);
2324         } else
2325                 audit_log_lost("rate limit exceeded");
2326 
2327         audit_buffer_free(ab);
2328 }
2329 
2330 /**
2331  * audit_log - Log an audit record
2332  * @ctx: audit context
2333  * @gfp_mask: type of allocation
2334  * @type: audit message type
2335  * @fmt: format string to use
2336  * @...: variable parameters matching the format string
2337  *
2338  * This is a convenience function that calls audit_log_start,
2339  * audit_log_vformat, and audit_log_end.  It may be called
2340  * in any context.
2341  */
2342 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
2343                const char *fmt, ...)
2344 {
2345         struct audit_buffer *ab;
2346         va_list args;
2347 
2348         ab = audit_log_start(ctx, gfp_mask, type);
2349         if (ab) {
2350                 va_start(args, fmt);
2351                 audit_log_vformat(ab, fmt, args);
2352                 va_end(args);
2353                 audit_log_end(ab);
2354         }
2355 }
2356 
2357 EXPORT_SYMBOL(audit_log_start);
2358 EXPORT_SYMBOL(audit_log_end);
2359 EXPORT_SYMBOL(audit_log_format);
2360 EXPORT_SYMBOL(audit_log);