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 #include <linux/security.h> 57 #include <linux/freezer.h> 58 #include <linux/pid_namespace.h> 59 #include <net/netns/generic.h> 60 61 #include "audit.h" 62 63 /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED. 64 * (Initialization happens after skb_init is called.) */ 65 #define AUDIT_DISABLED -1 66 #define AUDIT_UNINITIALIZED 0 67 #define AUDIT_INITIALIZED 1 68 static int audit_initialized = AUDIT_UNINITIALIZED; 69 70 u32 audit_enabled = AUDIT_OFF; 71 bool audit_ever_enabled = !!AUDIT_OFF; 72 73 EXPORT_SYMBOL_GPL(audit_enabled); 74 75 /* Default state when kernel boots without any parameters. */ 76 static u32 audit_default = AUDIT_OFF; 77 78 /* If auditing cannot proceed, audit_failure selects what happens. */ 79 static u32 audit_failure = AUDIT_FAIL_PRINTK; 80 81 /* private audit network namespace index */ 82 static unsigned int audit_net_id; 83 84 /** 85 * struct audit_net - audit private network namespace data 86 * @sk: communication socket 87 */ 88 struct audit_net { 89 struct sock *sk; 90 }; 91 92 /** 93 * struct auditd_connection - kernel/auditd connection state 94 * @pid: auditd PID 95 * @portid: netlink portid 96 * @net: the associated network namespace 97 * @rcu: RCU head 98 * 99 * Description: 100 * This struct is RCU protected; you must either hold the RCU lock for reading 101 * or the associated spinlock for writing. 102 */ 103 struct auditd_connection { 104 struct pid *pid; 105 u32 portid; 106 struct net *net; 107 struct rcu_head rcu; 108 }; 109 static struct auditd_connection __rcu *auditd_conn; 110 static DEFINE_SPINLOCK(auditd_conn_lock); 111 112 /* If audit_rate_limit is non-zero, limit the rate of sending audit records 113 * to that number per second. This prevents DoS attacks, but results in 114 * audit records being dropped. */ 115 static u32 audit_rate_limit; 116 117 /* Number of outstanding audit_buffers allowed. 118 * When set to zero, this means unlimited. */ 119 static u32 audit_backlog_limit = 64; 120 #define AUDIT_BACKLOG_WAIT_TIME (60 * HZ) 121 static u32 audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME; 122 123 /* The identity of the user shutting down the audit system. */ 124 static kuid_t audit_sig_uid = INVALID_UID; 125 static pid_t audit_sig_pid = -1; 126 static struct lsm_prop audit_sig_lsm; 127 128 /* Records can be lost in several ways: 129 0) [suppressed in audit_alloc] 130 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] 131 2) out of memory in audit_log_move [alloc_skb] 132 3) suppressed due to audit_rate_limit 133 4) suppressed due to audit_backlog_limit 134 */ 135 static atomic_t audit_lost = ATOMIC_INIT(0); 136 137 /* Monotonically increasing sum of time the kernel has spent 138 * waiting while the backlog limit is exceeded. 139 */ 140 static atomic_t audit_backlog_wait_time_actual = ATOMIC_INIT(0); 141 142 /* Hash for inode-based rules */ 143 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; 144 145 static struct kmem_cache *audit_buffer_cache; 146 147 /* queue msgs to send via kauditd_task */ 148 static struct sk_buff_head audit_queue; 149 /* queue msgs due to temporary unicast send problems */ 150 static struct sk_buff_head audit_retry_queue; 151 /* queue msgs waiting for new auditd connection */ 152 static struct sk_buff_head audit_hold_queue; 153 154 /* queue servicing thread */ 155 static struct task_struct *kauditd_task; 156 static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); 157 158 /* waitqueue for callers who are blocked on the audit backlog */ 159 static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); 160 161 static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION, 162 .mask = -1, 163 .features = 0, 164 .lock = 0,}; 165 166 static char *audit_feature_names[2] = { 167 "only_unset_loginuid", 168 "loginuid_immutable", 169 }; 170 171 /** 172 * struct audit_ctl_mutex - serialize requests from userspace 173 * @lock: the mutex used for locking 174 * @owner: the task which owns the lock 175 * 176 * Description: 177 * This is the lock struct used to ensure we only process userspace requests 178 * in an orderly fashion. We can't simply use a mutex/lock here because we 179 * need to track lock ownership so we don't end up blocking the lock owner in 180 * audit_log_start() or similar. 181 */ 182 static struct audit_ctl_mutex { 183 struct mutex lock; 184 void *owner; 185 } audit_cmd_mutex; 186 187 /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting 188 * audit records. Since printk uses a 1024 byte buffer, this buffer 189 * should be at least that large. */ 190 #define AUDIT_BUFSIZ 1024 191 192 /* The audit_buffer is used when formatting an audit record. The caller 193 * locks briefly to get the record off the freelist or to allocate the 194 * buffer, and locks briefly to send the buffer to the netlink layer or 195 * to place it on a transmit queue. Multiple audit_buffers can be in 196 * use simultaneously. */ 197 struct audit_buffer { 198 struct sk_buff *skb; /* formatted skb ready to send */ 199 struct audit_context *ctx; /* NULL or associated context */ 200 gfp_t gfp_mask; 201 }; 202 203 struct audit_reply { 204 __u32 portid; 205 struct net *net; 206 struct sk_buff *skb; 207 }; 208 209 /** 210 * auditd_test_task - Check to see if a given task is an audit daemon 211 * @task: the task to check 212 * 213 * Description: 214 * Return 1 if the task is a registered audit daemon, 0 otherwise. 215 */ 216 int auditd_test_task(struct task_struct *task) 217 { 218 int rc; 219 struct auditd_connection *ac; 220 221 rcu_read_lock(); 222 ac = rcu_dereference(auditd_conn); 223 rc = (ac && ac->pid == task_tgid(task) ? 1 : 0); 224 rcu_read_unlock(); 225 226 return rc; 227 } 228 229 /** 230 * audit_ctl_lock - Take the audit control lock 231 */ 232 void audit_ctl_lock(void) 233 { 234 mutex_lock(&audit_cmd_mutex.lock); 235 audit_cmd_mutex.owner = current; 236 } 237 238 /** 239 * audit_ctl_unlock - Drop the audit control lock 240 */ 241 void audit_ctl_unlock(void) 242 { 243 audit_cmd_mutex.owner = NULL; 244 mutex_unlock(&audit_cmd_mutex.lock); 245 } 246 247 /** 248 * audit_ctl_owner_current - Test to see if the current task owns the lock 249 * 250 * Description: 251 * Return true if the current task owns the audit control lock, false if it 252 * doesn't own the lock. 253 */ 254 static bool audit_ctl_owner_current(void) 255 { 256 return (current == audit_cmd_mutex.owner); 257 } 258 259 /** 260 * auditd_pid_vnr - Return the auditd PID relative to the namespace 261 * 262 * Description: 263 * Returns the PID in relation to the namespace, 0 on failure. 264 */ 265 static pid_t auditd_pid_vnr(void) 266 { 267 pid_t pid; 268 const struct auditd_connection *ac; 269 270 rcu_read_lock(); 271 ac = rcu_dereference(auditd_conn); 272 if (!ac || !ac->pid) 273 pid = 0; 274 else 275 pid = pid_vnr(ac->pid); 276 rcu_read_unlock(); 277 278 return pid; 279 } 280 281 /** 282 * audit_get_sk - Return the audit socket for the given network namespace 283 * @net: the destination network namespace 284 * 285 * Description: 286 * Returns the sock pointer if valid, NULL otherwise. The caller must ensure 287 * that a reference is held for the network namespace while the sock is in use. 288 */ 289 static struct sock *audit_get_sk(const struct net *net) 290 { 291 struct audit_net *aunet; 292 293 if (!net) 294 return NULL; 295 296 aunet = net_generic(net, audit_net_id); 297 return aunet->sk; 298 } 299 300 void audit_panic(const char *message) 301 { 302 switch (audit_failure) { 303 case AUDIT_FAIL_SILENT: 304 break; 305 case AUDIT_FAIL_PRINTK: 306 if (printk_ratelimit()) 307 pr_err("%s\n", message); 308 break; 309 case AUDIT_FAIL_PANIC: 310 panic("audit: %s\n", message); 311 break; 312 } 313 } 314 315 static inline int audit_rate_check(void) 316 { 317 static unsigned long last_check = 0; 318 static int messages = 0; 319 static DEFINE_SPINLOCK(lock); 320 unsigned long flags; 321 unsigned long now; 322 int retval = 0; 323 324 if (!audit_rate_limit) 325 return 1; 326 327 spin_lock_irqsave(&lock, flags); 328 if (++messages < audit_rate_limit) { 329 retval = 1; 330 } else { 331 now = jiffies; 332 if (time_after(now, last_check + HZ)) { 333 last_check = now; 334 messages = 0; 335 retval = 1; 336 } 337 } 338 spin_unlock_irqrestore(&lock, flags); 339 340 return retval; 341 } 342 343 /** 344 * audit_log_lost - conditionally log lost audit message event 345 * @message: the message stating reason for lost audit message 346 * 347 * Emit at least 1 message per second, even if audit_rate_check is 348 * throttling. 349 * Always increment the lost messages counter. 350 */ 351 void audit_log_lost(const char *message) 352 { 353 static unsigned long last_msg = 0; 354 static DEFINE_SPINLOCK(lock); 355 unsigned long flags; 356 unsigned long now; 357 int print; 358 359 atomic_inc(&audit_lost); 360 361 print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); 362 363 if (!print) { 364 spin_lock_irqsave(&lock, flags); 365 now = jiffies; 366 if (time_after(now, last_msg + HZ)) { 367 print = 1; 368 last_msg = now; 369 } 370 spin_unlock_irqrestore(&lock, flags); 371 } 372 373 if (print) { 374 if (printk_ratelimit()) 375 pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n", 376 atomic_read(&audit_lost), 377 audit_rate_limit, 378 audit_backlog_limit); 379 audit_panic(message); 380 } 381 } 382 383 static int audit_log_config_change(char *function_name, u32 new, u32 old, 384 int allow_changes) 385 { 386 struct audit_buffer *ab; 387 int rc = 0; 388 389 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE); 390 if (unlikely(!ab)) 391 return rc; 392 audit_log_format(ab, "op=set %s=%u old=%u ", function_name, new, old); 393 audit_log_session_info(ab); 394 rc = audit_log_task_context(ab); 395 if (rc) 396 allow_changes = 0; /* Something weird, deny request */ 397 audit_log_format(ab, " res=%d", allow_changes); 398 audit_log_end(ab); 399 return rc; 400 } 401 402 static int audit_do_config_change(char *function_name, u32 *to_change, u32 new) 403 { 404 int allow_changes, rc = 0; 405 u32 old = *to_change; 406 407 /* check if we are locked */ 408 if (audit_enabled == AUDIT_LOCKED) 409 allow_changes = 0; 410 else 411 allow_changes = 1; 412 413 if (audit_enabled != AUDIT_OFF) { 414 rc = audit_log_config_change(function_name, new, old, allow_changes); 415 if (rc) 416 allow_changes = 0; 417 } 418 419 /* If we are allowed, make the change */ 420 if (allow_changes == 1) 421 *to_change = new; 422 /* Not allowed, update reason */ 423 else if (rc == 0) 424 rc = -EPERM; 425 return rc; 426 } 427 428 static int audit_set_rate_limit(u32 limit) 429 { 430 return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit); 431 } 432 433 static int audit_set_backlog_limit(u32 limit) 434 { 435 return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit); 436 } 437 438 static int audit_set_backlog_wait_time(u32 timeout) 439 { 440 return audit_do_config_change("audit_backlog_wait_time", 441 &audit_backlog_wait_time, timeout); 442 } 443 444 static int audit_set_enabled(u32 state) 445 { 446 int rc; 447 if (state > AUDIT_LOCKED) 448 return -EINVAL; 449 450 rc = audit_do_config_change("audit_enabled", &audit_enabled, state); 451 if (!rc) 452 audit_ever_enabled |= !!state; 453 454 return rc; 455 } 456 457 static int audit_set_failure(u32 state) 458 { 459 if (state != AUDIT_FAIL_SILENT 460 && state != AUDIT_FAIL_PRINTK 461 && state != AUDIT_FAIL_PANIC) 462 return -EINVAL; 463 464 return audit_do_config_change("audit_failure", &audit_failure, state); 465 } 466 467 /** 468 * auditd_conn_free - RCU helper to release an auditd connection struct 469 * @rcu: RCU head 470 * 471 * Description: 472 * Drop any references inside the auditd connection tracking struct and free 473 * the memory. 474 */ 475 static void auditd_conn_free(struct rcu_head *rcu) 476 { 477 struct auditd_connection *ac; 478 479 ac = container_of(rcu, struct auditd_connection, rcu); 480 put_pid(ac->pid); 481 put_net(ac->net); 482 kfree(ac); 483 } 484 485 /** 486 * auditd_set - Set/Reset the auditd connection state 487 * @pid: auditd PID 488 * @portid: auditd netlink portid 489 * @net: auditd network namespace pointer 490 * @skb: the netlink command from the audit daemon 491 * @ack: netlink ack flag, cleared if ack'd here 492 * 493 * Description: 494 * This function will obtain and drop network namespace references as 495 * necessary. Returns zero on success, negative values on failure. 496 */ 497 static int auditd_set(struct pid *pid, u32 portid, struct net *net, 498 struct sk_buff *skb, bool *ack) 499 { 500 unsigned long flags; 501 struct auditd_connection *ac_old, *ac_new; 502 struct nlmsghdr *nlh; 503 504 if (!pid || !net) 505 return -EINVAL; 506 507 ac_new = kzalloc(sizeof(*ac_new), GFP_KERNEL); 508 if (!ac_new) 509 return -ENOMEM; 510 ac_new->pid = get_pid(pid); 511 ac_new->portid = portid; 512 ac_new->net = get_net(net); 513 514 /* send the ack now to avoid a race with the queue backlog */ 515 if (*ack) { 516 nlh = nlmsg_hdr(skb); 517 netlink_ack(skb, nlh, 0, NULL); 518 *ack = false; 519 } 520 521 spin_lock_irqsave(&auditd_conn_lock, flags); 522 ac_old = rcu_dereference_protected(auditd_conn, 523 lockdep_is_held(&auditd_conn_lock)); 524 rcu_assign_pointer(auditd_conn, ac_new); 525 spin_unlock_irqrestore(&auditd_conn_lock, flags); 526 527 if (ac_old) 528 call_rcu(&ac_old->rcu, auditd_conn_free); 529 530 return 0; 531 } 532 533 /** 534 * kauditd_printk_skb - Print the audit record to the ring buffer 535 * @skb: audit record 536 * 537 * Whatever the reason, this packet may not make it to the auditd connection 538 * so write it via printk so the information isn't completely lost. 539 */ 540 static void kauditd_printk_skb(struct sk_buff *skb) 541 { 542 struct nlmsghdr *nlh = nlmsg_hdr(skb); 543 char *data = nlmsg_data(nlh); 544 545 if (nlh->nlmsg_type != AUDIT_EOE && printk_ratelimit()) 546 pr_notice("type=%d %s\n", nlh->nlmsg_type, data); 547 } 548 549 /** 550 * kauditd_rehold_skb - Handle a audit record send failure in the hold queue 551 * @skb: audit record 552 * @error: error code (unused) 553 * 554 * Description: 555 * This should only be used by the kauditd_thread when it fails to flush the 556 * hold queue. 557 */ 558 static void kauditd_rehold_skb(struct sk_buff *skb, __always_unused int error) 559 { 560 /* put the record back in the queue */ 561 skb_queue_tail(&audit_hold_queue, skb); 562 } 563 564 /** 565 * kauditd_hold_skb - Queue an audit record, waiting for auditd 566 * @skb: audit record 567 * @error: error code 568 * 569 * Description: 570 * Queue the audit record, waiting for an instance of auditd. When this 571 * function is called we haven't given up yet on sending the record, but things 572 * are not looking good. The first thing we want to do is try to write the 573 * record via printk and then see if we want to try and hold on to the record 574 * and queue it, if we have room. If we want to hold on to the record, but we 575 * don't have room, record a record lost message. 576 */ 577 static void kauditd_hold_skb(struct sk_buff *skb, int error) 578 { 579 /* at this point it is uncertain if we will ever send this to auditd so 580 * try to send the message via printk before we go any further */ 581 kauditd_printk_skb(skb); 582 583 /* can we just silently drop the message? */ 584 if (!audit_default) 585 goto drop; 586 587 /* the hold queue is only for when the daemon goes away completely, 588 * not -EAGAIN failures; if we are in a -EAGAIN state requeue the 589 * record on the retry queue unless it's full, in which case drop it 590 */ 591 if (error == -EAGAIN) { 592 if (!audit_backlog_limit || 593 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) { 594 skb_queue_tail(&audit_retry_queue, skb); 595 return; 596 } 597 audit_log_lost("kauditd retry queue overflow"); 598 goto drop; 599 } 600 601 /* if we have room in the hold queue, queue the message */ 602 if (!audit_backlog_limit || 603 skb_queue_len(&audit_hold_queue) < audit_backlog_limit) { 604 skb_queue_tail(&audit_hold_queue, skb); 605 return; 606 } 607 608 /* we have no other options - drop the message */ 609 audit_log_lost("kauditd hold queue overflow"); 610 drop: 611 kfree_skb(skb); 612 } 613 614 /** 615 * kauditd_retry_skb - Queue an audit record, attempt to send again to auditd 616 * @skb: audit record 617 * @error: error code (unused) 618 * 619 * Description: 620 * Not as serious as kauditd_hold_skb() as we still have a connected auditd, 621 * but for some reason we are having problems sending it audit records so 622 * queue the given record and attempt to resend. 623 */ 624 static void kauditd_retry_skb(struct sk_buff *skb, __always_unused int error) 625 { 626 if (!audit_backlog_limit || 627 skb_queue_len(&audit_retry_queue) < audit_backlog_limit) { 628 skb_queue_tail(&audit_retry_queue, skb); 629 return; 630 } 631 632 /* we have to drop the record, send it via printk as a last effort */ 633 kauditd_printk_skb(skb); 634 audit_log_lost("kauditd retry queue overflow"); 635 kfree_skb(skb); 636 } 637 638 /** 639 * auditd_reset - Disconnect the auditd connection 640 * @ac: auditd connection state 641 * 642 * Description: 643 * Break the auditd/kauditd connection and move all the queued records into the 644 * hold queue in case auditd reconnects. It is important to note that the @ac 645 * pointer should never be dereferenced inside this function as it may be NULL 646 * or invalid, you can only compare the memory address! If @ac is NULL then 647 * the connection will always be reset. 648 */ 649 static void auditd_reset(const struct auditd_connection *ac) 650 { 651 unsigned long flags; 652 struct sk_buff *skb; 653 struct auditd_connection *ac_old; 654 655 /* if it isn't already broken, break the connection */ 656 spin_lock_irqsave(&auditd_conn_lock, flags); 657 ac_old = rcu_dereference_protected(auditd_conn, 658 lockdep_is_held(&auditd_conn_lock)); 659 if (ac && ac != ac_old) { 660 /* someone already registered a new auditd connection */ 661 spin_unlock_irqrestore(&auditd_conn_lock, flags); 662 return; 663 } 664 rcu_assign_pointer(auditd_conn, NULL); 665 spin_unlock_irqrestore(&auditd_conn_lock, flags); 666 667 if (ac_old) 668 call_rcu(&ac_old->rcu, auditd_conn_free); 669 670 /* flush the retry queue to the hold queue, but don't touch the main 671 * queue since we need to process that normally for multicast */ 672 while ((skb = skb_dequeue(&audit_retry_queue))) 673 kauditd_hold_skb(skb, -ECONNREFUSED); 674 } 675 676 /** 677 * auditd_send_unicast_skb - Send a record via unicast to auditd 678 * @skb: audit record 679 * 680 * Description: 681 * Send a skb to the audit daemon, returns positive/zero values on success and 682 * negative values on failure; in all cases the skb will be consumed by this 683 * function. If the send results in -ECONNREFUSED the connection with auditd 684 * will be reset. This function may sleep so callers should not hold any locks 685 * where this would cause a problem. 686 */ 687 static int auditd_send_unicast_skb(struct sk_buff *skb) 688 { 689 int rc; 690 u32 portid; 691 struct net *net; 692 struct sock *sk; 693 struct auditd_connection *ac; 694 695 /* NOTE: we can't call netlink_unicast while in the RCU section so 696 * take a reference to the network namespace and grab local 697 * copies of the namespace, the sock, and the portid; the 698 * namespace and sock aren't going to go away while we hold a 699 * reference and if the portid does become invalid after the RCU 700 * section netlink_unicast() should safely return an error */ 701 702 rcu_read_lock(); 703 ac = rcu_dereference(auditd_conn); 704 if (!ac) { 705 rcu_read_unlock(); 706 kfree_skb(skb); 707 rc = -ECONNREFUSED; 708 goto err; 709 } 710 net = get_net(ac->net); 711 sk = audit_get_sk(net); 712 portid = ac->portid; 713 rcu_read_unlock(); 714 715 rc = netlink_unicast(sk, skb, portid, 0); 716 put_net(net); 717 if (rc < 0) 718 goto err; 719 720 return rc; 721 722 err: 723 if (ac && rc == -ECONNREFUSED) 724 auditd_reset(ac); 725 return rc; 726 } 727 728 /** 729 * kauditd_send_queue - Helper for kauditd_thread to flush skb queues 730 * @sk: the sending sock 731 * @portid: the netlink destination 732 * @queue: the skb queue to process 733 * @retry_limit: limit on number of netlink unicast failures 734 * @skb_hook: per-skb hook for additional processing 735 * @err_hook: hook called if the skb fails the netlink unicast send 736 * 737 * Description: 738 * Run through the given queue and attempt to send the audit records to auditd, 739 * returns zero on success, negative values on failure. It is up to the caller 740 * to ensure that the @sk is valid for the duration of this function. 741 * 742 */ 743 static int kauditd_send_queue(struct sock *sk, u32 portid, 744 struct sk_buff_head *queue, 745 unsigned int retry_limit, 746 void (*skb_hook)(struct sk_buff *skb), 747 void (*err_hook)(struct sk_buff *skb, int error)) 748 { 749 int rc = 0; 750 struct sk_buff *skb = NULL; 751 struct sk_buff *skb_tail; 752 unsigned int failed = 0; 753 754 /* NOTE: kauditd_thread takes care of all our locking, we just use 755 * the netlink info passed to us (e.g. sk and portid) */ 756 757 skb_tail = skb_peek_tail(queue); 758 while ((skb != skb_tail) && (skb = skb_dequeue(queue))) { 759 /* call the skb_hook for each skb we touch */ 760 if (skb_hook) 761 (*skb_hook)(skb); 762 763 /* can we send to anyone via unicast? */ 764 if (!sk) { 765 if (err_hook) 766 (*err_hook)(skb, -ECONNREFUSED); 767 continue; 768 } 769 770 retry: 771 /* grab an extra skb reference in case of error */ 772 skb_get(skb); 773 rc = netlink_unicast(sk, skb, portid, 0); 774 if (rc < 0) { 775 /* send failed - try a few times unless fatal error */ 776 if (++failed >= retry_limit || 777 rc == -ECONNREFUSED || rc == -EPERM) { 778 sk = NULL; 779 if (err_hook) 780 (*err_hook)(skb, rc); 781 if (rc == -EAGAIN) 782 rc = 0; 783 /* continue to drain the queue */ 784 continue; 785 } else 786 goto retry; 787 } else { 788 /* skb sent - drop the extra reference and continue */ 789 consume_skb(skb); 790 failed = 0; 791 } 792 } 793 794 return (rc >= 0 ? 0 : rc); 795 } 796 797 /* 798 * kauditd_send_multicast_skb - Send a record to any multicast listeners 799 * @skb: audit record 800 * 801 * Description: 802 * Write a multicast message to anyone listening in the initial network 803 * namespace. This function doesn't consume an skb as might be expected since 804 * it has to copy it anyways. 805 */ 806 static void kauditd_send_multicast_skb(struct sk_buff *skb) 807 { 808 struct sk_buff *copy; 809 struct sock *sock = audit_get_sk(&init_net); 810 struct nlmsghdr *nlh; 811 812 /* NOTE: we are not taking an additional reference for init_net since 813 * we don't have to worry about it going away */ 814 815 if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG)) 816 return; 817 818 /* 819 * The seemingly wasteful skb_copy() rather than bumping the refcount 820 * using skb_get() is necessary because non-standard mods are made to 821 * the skb by the original kaudit unicast socket send routine. The 822 * existing auditd daemon assumes this breakage. Fixing this would 823 * require co-ordinating a change in the established protocol between 824 * the kaudit kernel subsystem and the auditd userspace code. There is 825 * no reason for new multicast clients to continue with this 826 * non-compliance. 827 */ 828 copy = skb_copy(skb, GFP_KERNEL); 829 if (!copy) 830 return; 831 nlh = nlmsg_hdr(copy); 832 nlh->nlmsg_len = skb->len; 833 834 nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL); 835 } 836 837 /** 838 * kauditd_thread - Worker thread to send audit records to userspace 839 * @dummy: unused 840 */ 841 static int kauditd_thread(void *dummy) 842 { 843 int rc; 844 u32 portid = 0; 845 struct net *net = NULL; 846 struct sock *sk = NULL; 847 struct auditd_connection *ac; 848 849 #define UNICAST_RETRIES 5 850 851 set_freezable(); 852 while (!kthread_should_stop()) { 853 /* NOTE: see the lock comments in auditd_send_unicast_skb() */ 854 rcu_read_lock(); 855 ac = rcu_dereference(auditd_conn); 856 if (!ac) { 857 rcu_read_unlock(); 858 goto main_queue; 859 } 860 net = get_net(ac->net); 861 sk = audit_get_sk(net); 862 portid = ac->portid; 863 rcu_read_unlock(); 864 865 /* attempt to flush the hold queue */ 866 rc = kauditd_send_queue(sk, portid, 867 &audit_hold_queue, UNICAST_RETRIES, 868 NULL, kauditd_rehold_skb); 869 if (rc < 0) { 870 sk = NULL; 871 auditd_reset(ac); 872 goto main_queue; 873 } 874 875 /* attempt to flush the retry queue */ 876 rc = kauditd_send_queue(sk, portid, 877 &audit_retry_queue, UNICAST_RETRIES, 878 NULL, kauditd_hold_skb); 879 if (rc < 0) { 880 sk = NULL; 881 auditd_reset(ac); 882 goto main_queue; 883 } 884 885 main_queue: 886 /* process the main queue - do the multicast send and attempt 887 * unicast, dump failed record sends to the retry queue; if 888 * sk == NULL due to previous failures we will just do the 889 * multicast send and move the record to the hold queue */ 890 rc = kauditd_send_queue(sk, portid, &audit_queue, 1, 891 kauditd_send_multicast_skb, 892 (sk ? 893 kauditd_retry_skb : kauditd_hold_skb)); 894 if (ac && rc < 0) 895 auditd_reset(ac); 896 sk = NULL; 897 898 /* drop our netns reference, no auditd sends past this line */ 899 if (net) { 900 put_net(net); 901 net = NULL; 902 } 903 904 /* we have processed all the queues so wake everyone */ 905 wake_up(&audit_backlog_wait); 906 907 /* NOTE: we want to wake up if there is anything on the queue, 908 * regardless of if an auditd is connected, as we need to 909 * do the multicast send and rotate records from the 910 * main queue to the retry/hold queues */ 911 wait_event_freezable(kauditd_wait, 912 (skb_queue_len(&audit_queue) ? 1 : 0)); 913 } 914 915 return 0; 916 } 917 918 int audit_send_list_thread(void *_dest) 919 { 920 struct audit_netlink_list *dest = _dest; 921 struct sk_buff *skb; 922 struct sock *sk = audit_get_sk(dest->net); 923 924 /* wait for parent to finish and send an ACK */ 925 audit_ctl_lock(); 926 audit_ctl_unlock(); 927 928 while ((skb = __skb_dequeue(&dest->q)) != NULL) 929 netlink_unicast(sk, skb, dest->portid, 0); 930 931 put_net(dest->net); 932 kfree(dest); 933 934 return 0; 935 } 936 937 struct sk_buff *audit_make_reply(int seq, int type, int done, 938 int multi, const void *payload, int size) 939 { 940 struct sk_buff *skb; 941 struct nlmsghdr *nlh; 942 void *data; 943 int flags = multi ? NLM_F_MULTI : 0; 944 int t = done ? NLMSG_DONE : type; 945 946 skb = nlmsg_new(size, GFP_KERNEL); 947 if (!skb) 948 return NULL; 949 950 nlh = nlmsg_put(skb, 0, seq, t, size, flags); 951 if (!nlh) 952 goto out_kfree_skb; 953 data = nlmsg_data(nlh); 954 memcpy(data, payload, size); 955 return skb; 956 957 out_kfree_skb: 958 kfree_skb(skb); 959 return NULL; 960 } 961 962 static void audit_free_reply(struct audit_reply *reply) 963 { 964 if (!reply) 965 return; 966 967 kfree_skb(reply->skb); 968 if (reply->net) 969 put_net(reply->net); 970 kfree(reply); 971 } 972 973 static int audit_send_reply_thread(void *arg) 974 { 975 struct audit_reply *reply = (struct audit_reply *)arg; 976 977 audit_ctl_lock(); 978 audit_ctl_unlock(); 979 980 /* Ignore failure. It'll only happen if the sender goes away, 981 because our timeout is set to infinite. */ 982 netlink_unicast(audit_get_sk(reply->net), reply->skb, reply->portid, 0); 983 reply->skb = NULL; 984 audit_free_reply(reply); 985 return 0; 986 } 987 988 /** 989 * audit_send_reply - send an audit reply message via netlink 990 * @request_skb: skb of request we are replying to (used to target the reply) 991 * @seq: sequence number 992 * @type: audit message type 993 * @done: done (last) flag 994 * @multi: multi-part message flag 995 * @payload: payload data 996 * @size: payload size 997 * 998 * Allocates a skb, builds the netlink message, and sends it to the port id. 999 */ 1000 static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done, 1001 int multi, const void *payload, int size) 1002 { 1003 struct task_struct *tsk; 1004 struct audit_reply *reply; 1005 1006 reply = kzalloc(sizeof(*reply), GFP_KERNEL); 1007 if (!reply) 1008 return; 1009 1010 reply->skb = audit_make_reply(seq, type, done, multi, payload, size); 1011 if (!reply->skb) 1012 goto err; 1013 reply->net = get_net(sock_net(NETLINK_CB(request_skb).sk)); 1014 reply->portid = NETLINK_CB(request_skb).portid; 1015 1016 tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); 1017 if (IS_ERR(tsk)) 1018 goto err; 1019 1020 return; 1021 1022 err: 1023 audit_free_reply(reply); 1024 } 1025 1026 /* 1027 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit 1028 * control messages. 1029 */ 1030 static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) 1031 { 1032 int err = 0; 1033 1034 /* Only support initial user namespace for now. */ 1035 /* 1036 * We return ECONNREFUSED because it tricks userspace into thinking 1037 * that audit was not configured into the kernel. Lots of users 1038 * configure their PAM stack (because that's what the distro does) 1039 * to reject login if unable to send messages to audit. If we return 1040 * ECONNREFUSED the PAM stack thinks the kernel does not have audit 1041 * configured in and will let login proceed. If we return EPERM 1042 * userspace will reject all logins. This should be removed when we 1043 * support non init namespaces!! 1044 */ 1045 if (current_user_ns() != &init_user_ns) 1046 return -ECONNREFUSED; 1047 1048 switch (msg_type) { 1049 case AUDIT_LIST: 1050 case AUDIT_ADD: 1051 case AUDIT_DEL: 1052 return -EOPNOTSUPP; 1053 case AUDIT_GET: 1054 case AUDIT_SET: 1055 case AUDIT_GET_FEATURE: 1056 case AUDIT_SET_FEATURE: 1057 case AUDIT_LIST_RULES: 1058 case AUDIT_ADD_RULE: 1059 case AUDIT_DEL_RULE: 1060 case AUDIT_SIGNAL_INFO: 1061 case AUDIT_TTY_GET: 1062 case AUDIT_TTY_SET: 1063 case AUDIT_TRIM: 1064 case AUDIT_MAKE_EQUIV: 1065 /* Only support auditd and auditctl in initial pid namespace 1066 * for now. */ 1067 if (task_active_pid_ns(current) != &init_pid_ns) 1068 return -EPERM; 1069 1070 if (!netlink_capable(skb, CAP_AUDIT_CONTROL)) 1071 err = -EPERM; 1072 break; 1073 case AUDIT_USER: 1074 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: 1075 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: 1076 if (!netlink_capable(skb, CAP_AUDIT_WRITE)) 1077 err = -EPERM; 1078 break; 1079 default: /* bad msg */ 1080 err = -EINVAL; 1081 } 1082 1083 return err; 1084 } 1085 1086 static void audit_log_common_recv_msg(struct audit_context *context, 1087 struct audit_buffer **ab, u16 msg_type) 1088 { 1089 uid_t uid = from_kuid(&init_user_ns, current_uid()); 1090 pid_t pid = task_tgid_nr(current); 1091 1092 if (!audit_enabled && msg_type != AUDIT_USER_AVC) { 1093 *ab = NULL; 1094 return; 1095 } 1096 1097 *ab = audit_log_start(context, GFP_KERNEL, msg_type); 1098 if (unlikely(!*ab)) 1099 return; 1100 audit_log_format(*ab, "pid=%d uid=%u ", pid, uid); 1101 audit_log_session_info(*ab); 1102 audit_log_task_context(*ab); 1103 } 1104 1105 static inline void audit_log_user_recv_msg(struct audit_buffer **ab, 1106 u16 msg_type) 1107 { 1108 audit_log_common_recv_msg(NULL, ab, msg_type); 1109 } 1110 1111 static int is_audit_feature_set(int i) 1112 { 1113 return af.features & AUDIT_FEATURE_TO_MASK(i); 1114 } 1115 1116 1117 static int audit_get_feature(struct sk_buff *skb) 1118 { 1119 u32 seq; 1120 1121 seq = nlmsg_hdr(skb)->nlmsg_seq; 1122 1123 audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af)); 1124 1125 return 0; 1126 } 1127 1128 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature, 1129 u32 old_lock, u32 new_lock, int res) 1130 { 1131 struct audit_buffer *ab; 1132 1133 if (audit_enabled == AUDIT_OFF) 1134 return; 1135 1136 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE); 1137 if (!ab) 1138 return; 1139 audit_log_task_info(ab); 1140 audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d", 1141 audit_feature_names[which], !!old_feature, !!new_feature, 1142 !!old_lock, !!new_lock, res); 1143 audit_log_end(ab); 1144 } 1145 1146 static int audit_set_feature(struct audit_features *uaf) 1147 { 1148 int i; 1149 1150 BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names)); 1151 1152 /* if there is ever a version 2 we should handle that here */ 1153 1154 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) { 1155 u32 feature = AUDIT_FEATURE_TO_MASK(i); 1156 u32 old_feature, new_feature, old_lock, new_lock; 1157 1158 /* if we are not changing this feature, move along */ 1159 if (!(feature & uaf->mask)) 1160 continue; 1161 1162 old_feature = af.features & feature; 1163 new_feature = uaf->features & feature; 1164 new_lock = (uaf->lock | af.lock) & feature; 1165 old_lock = af.lock & feature; 1166 1167 /* are we changing a locked feature? */ 1168 if (old_lock && (new_feature != old_feature)) { 1169 audit_log_feature_change(i, old_feature, new_feature, 1170 old_lock, new_lock, 0); 1171 return -EPERM; 1172 } 1173 } 1174 /* nothing invalid, do the changes */ 1175 for (i = 0; i <= AUDIT_LAST_FEATURE; i++) { 1176 u32 feature = AUDIT_FEATURE_TO_MASK(i); 1177 u32 old_feature, new_feature, old_lock, new_lock; 1178 1179 /* if we are not changing this feature, move along */ 1180 if (!(feature & uaf->mask)) 1181 continue; 1182 1183 old_feature = af.features & feature; 1184 new_feature = uaf->features & feature; 1185 old_lock = af.lock & feature; 1186 new_lock = (uaf->lock | af.lock) & feature; 1187 1188 if (new_feature != old_feature) 1189 audit_log_feature_change(i, old_feature, new_feature, 1190 old_lock, new_lock, 1); 1191 1192 if (new_feature) 1193 af.features |= feature; 1194 else 1195 af.features &= ~feature; 1196 af.lock |= new_lock; 1197 } 1198 1199 return 0; 1200 } 1201 1202 static int audit_replace(struct pid *pid) 1203 { 1204 pid_t pvnr; 1205 struct sk_buff *skb; 1206 1207 pvnr = pid_vnr(pid); 1208 skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr)); 1209 if (!skb) 1210 return -ENOMEM; 1211 return auditd_send_unicast_skb(skb); 1212 } 1213 1214 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh, 1215 bool *ack) 1216 { 1217 u32 seq; 1218 void *data; 1219 int data_len; 1220 int err; 1221 struct audit_buffer *ab; 1222 u16 msg_type = nlh->nlmsg_type; 1223 struct audit_sig_info *sig_data; 1224 char *ctx = NULL; 1225 u32 len; 1226 1227 err = audit_netlink_ok(skb, msg_type); 1228 if (err) 1229 return err; 1230 1231 seq = nlh->nlmsg_seq; 1232 data = nlmsg_data(nlh); 1233 data_len = nlmsg_len(nlh); 1234 1235 switch (msg_type) { 1236 case AUDIT_GET: { 1237 struct audit_status s; 1238 memset(&s, 0, sizeof(s)); 1239 s.enabled = audit_enabled; 1240 s.failure = audit_failure; 1241 /* NOTE: use pid_vnr() so the PID is relative to the current 1242 * namespace */ 1243 s.pid = auditd_pid_vnr(); 1244 s.rate_limit = audit_rate_limit; 1245 s.backlog_limit = audit_backlog_limit; 1246 s.lost = atomic_read(&audit_lost); 1247 s.backlog = skb_queue_len(&audit_queue); 1248 s.feature_bitmap = AUDIT_FEATURE_BITMAP_ALL; 1249 s.backlog_wait_time = audit_backlog_wait_time; 1250 s.backlog_wait_time_actual = atomic_read(&audit_backlog_wait_time_actual); 1251 audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s)); 1252 break; 1253 } 1254 case AUDIT_SET: { 1255 struct audit_status s; 1256 memset(&s, 0, sizeof(s)); 1257 /* guard against past and future API changes */ 1258 memcpy(&s, data, min_t(size_t, sizeof(s), data_len)); 1259 if (s.mask & AUDIT_STATUS_ENABLED) { 1260 err = audit_set_enabled(s.enabled); 1261 if (err < 0) 1262 return err; 1263 } 1264 if (s.mask & AUDIT_STATUS_FAILURE) { 1265 err = audit_set_failure(s.failure); 1266 if (err < 0) 1267 return err; 1268 } 1269 if (s.mask & AUDIT_STATUS_PID) { 1270 /* NOTE: we are using the vnr PID functions below 1271 * because the s.pid value is relative to the 1272 * namespace of the caller; at present this 1273 * doesn't matter much since you can really only 1274 * run auditd from the initial pid namespace, but 1275 * something to keep in mind if this changes */ 1276 pid_t new_pid = s.pid; 1277 pid_t auditd_pid; 1278 struct pid *req_pid = task_tgid(current); 1279 1280 /* Sanity check - PID values must match. Setting 1281 * pid to 0 is how auditd ends auditing. */ 1282 if (new_pid && (new_pid != pid_vnr(req_pid))) 1283 return -EINVAL; 1284 1285 /* test the auditd connection */ 1286 audit_replace(req_pid); 1287 1288 auditd_pid = auditd_pid_vnr(); 1289 if (auditd_pid) { 1290 /* replacing a healthy auditd is not allowed */ 1291 if (new_pid) { 1292 audit_log_config_change("audit_pid", 1293 new_pid, auditd_pid, 0); 1294 return -EEXIST; 1295 } 1296 /* only current auditd can unregister itself */ 1297 if (pid_vnr(req_pid) != auditd_pid) { 1298 audit_log_config_change("audit_pid", 1299 new_pid, auditd_pid, 0); 1300 return -EACCES; 1301 } 1302 } 1303 1304 if (new_pid) { 1305 /* register a new auditd connection */ 1306 err = auditd_set(req_pid, 1307 NETLINK_CB(skb).portid, 1308 sock_net(NETLINK_CB(skb).sk), 1309 skb, ack); 1310 if (audit_enabled != AUDIT_OFF) 1311 audit_log_config_change("audit_pid", 1312 new_pid, 1313 auditd_pid, 1314 err ? 0 : 1); 1315 if (err) 1316 return err; 1317 1318 /* try to process any backlog */ 1319 wake_up_interruptible(&kauditd_wait); 1320 } else { 1321 if (audit_enabled != AUDIT_OFF) 1322 audit_log_config_change("audit_pid", 1323 new_pid, 1324 auditd_pid, 1); 1325 1326 /* unregister the auditd connection */ 1327 auditd_reset(NULL); 1328 } 1329 } 1330 if (s.mask & AUDIT_STATUS_RATE_LIMIT) { 1331 err = audit_set_rate_limit(s.rate_limit); 1332 if (err < 0) 1333 return err; 1334 } 1335 if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) { 1336 err = audit_set_backlog_limit(s.backlog_limit); 1337 if (err < 0) 1338 return err; 1339 } 1340 if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) { 1341 if (sizeof(s) > (size_t)nlh->nlmsg_len) 1342 return -EINVAL; 1343 if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME) 1344 return -EINVAL; 1345 err = audit_set_backlog_wait_time(s.backlog_wait_time); 1346 if (err < 0) 1347 return err; 1348 } 1349 if (s.mask == AUDIT_STATUS_LOST) { 1350 u32 lost = atomic_xchg(&audit_lost, 0); 1351 1352 audit_log_config_change("lost", 0, lost, 1); 1353 return lost; 1354 } 1355 if (s.mask == AUDIT_STATUS_BACKLOG_WAIT_TIME_ACTUAL) { 1356 u32 actual = atomic_xchg(&audit_backlog_wait_time_actual, 0); 1357 1358 audit_log_config_change("backlog_wait_time_actual", 0, actual, 1); 1359 return actual; 1360 } 1361 break; 1362 } 1363 case AUDIT_GET_FEATURE: 1364 err = audit_get_feature(skb); 1365 if (err) 1366 return err; 1367 break; 1368 case AUDIT_SET_FEATURE: 1369 if (data_len < sizeof(struct audit_features)) 1370 return -EINVAL; 1371 err = audit_set_feature(data); 1372 if (err) 1373 return err; 1374 break; 1375 case AUDIT_USER: 1376 case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: 1377 case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: 1378 if (!audit_enabled && msg_type != AUDIT_USER_AVC) 1379 return 0; 1380 /* exit early if there isn't at least one character to print */ 1381 if (data_len < 2) 1382 return -EINVAL; 1383 1384 err = audit_filter(msg_type, AUDIT_FILTER_USER); 1385 if (err == 1) { /* match or error */ 1386 char *str = data; 1387 1388 err = 0; 1389 if (msg_type == AUDIT_USER_TTY) { 1390 err = tty_audit_push(); 1391 if (err) 1392 break; 1393 } 1394 audit_log_user_recv_msg(&ab, msg_type); 1395 if (msg_type != AUDIT_USER_TTY) { 1396 /* ensure NULL termination */ 1397 str[data_len - 1] = '\0'; 1398 audit_log_format(ab, " msg='%.*s'", 1399 AUDIT_MESSAGE_TEXT_MAX, 1400 str); 1401 } else { 1402 audit_log_format(ab, " data="); 1403 if (str[data_len - 1] == '\0') 1404 data_len--; 1405 audit_log_n_untrustedstring(ab, str, data_len); 1406 } 1407 audit_log_end(ab); 1408 } 1409 break; 1410 case AUDIT_ADD_RULE: 1411 case AUDIT_DEL_RULE: 1412 if (data_len < sizeof(struct audit_rule_data)) 1413 return -EINVAL; 1414 if (audit_enabled == AUDIT_LOCKED) { 1415 audit_log_common_recv_msg(audit_context(), &ab, 1416 AUDIT_CONFIG_CHANGE); 1417 audit_log_format(ab, " op=%s audit_enabled=%d res=0", 1418 msg_type == AUDIT_ADD_RULE ? 1419 "add_rule" : "remove_rule", 1420 audit_enabled); 1421 audit_log_end(ab); 1422 return -EPERM; 1423 } 1424 err = audit_rule_change(msg_type, seq, data, data_len); 1425 break; 1426 case AUDIT_LIST_RULES: 1427 err = audit_list_rules_send(skb, seq); 1428 break; 1429 case AUDIT_TRIM: 1430 audit_trim_trees(); 1431 audit_log_common_recv_msg(audit_context(), &ab, 1432 AUDIT_CONFIG_CHANGE); 1433 audit_log_format(ab, " op=trim res=1"); 1434 audit_log_end(ab); 1435 break; 1436 case AUDIT_MAKE_EQUIV: { 1437 void *bufp = data; 1438 u32 sizes[2]; 1439 size_t msglen = data_len; 1440 char *old, *new; 1441 1442 err = -EINVAL; 1443 if (msglen < 2 * sizeof(u32)) 1444 break; 1445 memcpy(sizes, bufp, 2 * sizeof(u32)); 1446 bufp += 2 * sizeof(u32); 1447 msglen -= 2 * sizeof(u32); 1448 old = audit_unpack_string(&bufp, &msglen, sizes[0]); 1449 if (IS_ERR(old)) { 1450 err = PTR_ERR(old); 1451 break; 1452 } 1453 new = audit_unpack_string(&bufp, &msglen, sizes[1]); 1454 if (IS_ERR(new)) { 1455 err = PTR_ERR(new); 1456 kfree(old); 1457 break; 1458 } 1459 /* OK, here comes... */ 1460 err = audit_tag_tree(old, new); 1461 1462 audit_log_common_recv_msg(audit_context(), &ab, 1463 AUDIT_CONFIG_CHANGE); 1464 audit_log_format(ab, " op=make_equiv old="); 1465 audit_log_untrustedstring(ab, old); 1466 audit_log_format(ab, " new="); 1467 audit_log_untrustedstring(ab, new); 1468 audit_log_format(ab, " res=%d", !err); 1469 audit_log_end(ab); 1470 kfree(old); 1471 kfree(new); 1472 break; 1473 } 1474 case AUDIT_SIGNAL_INFO: 1475 len = 0; 1476 if (lsmprop_is_set(&audit_sig_lsm)) { 1477 err = security_lsmprop_to_secctx(&audit_sig_lsm, &ctx, 1478 &len); 1479 if (err) 1480 return err; 1481 } 1482 sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL); 1483 if (!sig_data) { 1484 if (lsmprop_is_set(&audit_sig_lsm)) 1485 security_release_secctx(ctx, len); 1486 return -ENOMEM; 1487 } 1488 sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid); 1489 sig_data->pid = audit_sig_pid; 1490 if (lsmprop_is_set(&audit_sig_lsm)) { 1491 memcpy(sig_data->ctx, ctx, len); 1492 security_release_secctx(ctx, len); 1493 } 1494 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0, 1495 sig_data, struct_size(sig_data, ctx, len)); 1496 kfree(sig_data); 1497 break; 1498 case AUDIT_TTY_GET: { 1499 struct audit_tty_status s; 1500 unsigned int t; 1501 1502 t = READ_ONCE(current->signal->audit_tty); 1503 s.enabled = t & AUDIT_TTY_ENABLE; 1504 s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD); 1505 1506 audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); 1507 break; 1508 } 1509 case AUDIT_TTY_SET: { 1510 struct audit_tty_status s, old; 1511 struct audit_buffer *ab; 1512 unsigned int t; 1513 1514 memset(&s, 0, sizeof(s)); 1515 /* guard against past and future API changes */ 1516 memcpy(&s, data, min_t(size_t, sizeof(s), data_len)); 1517 /* check if new data is valid */ 1518 if ((s.enabled != 0 && s.enabled != 1) || 1519 (s.log_passwd != 0 && s.log_passwd != 1)) 1520 err = -EINVAL; 1521 1522 if (err) 1523 t = READ_ONCE(current->signal->audit_tty); 1524 else { 1525 t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD); 1526 t = xchg(¤t->signal->audit_tty, t); 1527 } 1528 old.enabled = t & AUDIT_TTY_ENABLE; 1529 old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD); 1530 1531 audit_log_common_recv_msg(audit_context(), &ab, 1532 AUDIT_CONFIG_CHANGE); 1533 audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d" 1534 " old-log_passwd=%d new-log_passwd=%d res=%d", 1535 old.enabled, s.enabled, old.log_passwd, 1536 s.log_passwd, !err); 1537 audit_log_end(ab); 1538 break; 1539 } 1540 default: 1541 err = -EINVAL; 1542 break; 1543 } 1544 1545 return err < 0 ? err : 0; 1546 } 1547 1548 /** 1549 * audit_receive - receive messages from a netlink control socket 1550 * @skb: the message buffer 1551 * 1552 * Parse the provided skb and deal with any messages that may be present, 1553 * malformed skbs are discarded. 1554 */ 1555 static void audit_receive(struct sk_buff *skb) 1556 { 1557 struct nlmsghdr *nlh; 1558 bool ack; 1559 /* 1560 * len MUST be signed for nlmsg_next to be able to dec it below 0 1561 * if the nlmsg_len was not aligned 1562 */ 1563 int len; 1564 int err; 1565 1566 nlh = nlmsg_hdr(skb); 1567 len = skb->len; 1568 1569 audit_ctl_lock(); 1570 while (nlmsg_ok(nlh, len)) { 1571 ack = nlh->nlmsg_flags & NLM_F_ACK; 1572 err = audit_receive_msg(skb, nlh, &ack); 1573 1574 /* send an ack if the user asked for one and audit_receive_msg 1575 * didn't already do it, or if there was an error. */ 1576 if (ack || err) 1577 netlink_ack(skb, nlh, err, NULL); 1578 1579 nlh = nlmsg_next(nlh, &len); 1580 } 1581 audit_ctl_unlock(); 1582 1583 /* can't block with the ctrl lock, so penalize the sender now */ 1584 if (audit_backlog_limit && 1585 (skb_queue_len(&audit_queue) > audit_backlog_limit)) { 1586 DECLARE_WAITQUEUE(wait, current); 1587 1588 /* wake kauditd to try and flush the queue */ 1589 wake_up_interruptible(&kauditd_wait); 1590 1591 add_wait_queue_exclusive(&audit_backlog_wait, &wait); 1592 set_current_state(TASK_UNINTERRUPTIBLE); 1593 schedule_timeout(audit_backlog_wait_time); 1594 remove_wait_queue(&audit_backlog_wait, &wait); 1595 } 1596 } 1597 1598 /* Log information about who is connecting to the audit multicast socket */ 1599 static void audit_log_multicast(int group, const char *op, int err) 1600 { 1601 const struct cred *cred; 1602 struct tty_struct *tty; 1603 char comm[sizeof(current->comm)]; 1604 struct audit_buffer *ab; 1605 1606 if (!audit_enabled) 1607 return; 1608 1609 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_EVENT_LISTENER); 1610 if (!ab) 1611 return; 1612 1613 cred = current_cred(); 1614 tty = audit_get_tty(); 1615 audit_log_format(ab, "pid=%u uid=%u auid=%u tty=%s ses=%u", 1616 task_tgid_nr(current), 1617 from_kuid(&init_user_ns, cred->uid), 1618 from_kuid(&init_user_ns, audit_get_loginuid(current)), 1619 tty ? tty_name(tty) : "(none)", 1620 audit_get_sessionid(current)); 1621 audit_put_tty(tty); 1622 audit_log_task_context(ab); /* subj= */ 1623 audit_log_format(ab, " comm="); 1624 audit_log_untrustedstring(ab, get_task_comm(comm, current)); 1625 audit_log_d_path_exe(ab, current->mm); /* exe= */ 1626 audit_log_format(ab, " nl-mcgrp=%d op=%s res=%d", group, op, !err); 1627 audit_log_end(ab); 1628 } 1629 1630 /* Run custom bind function on netlink socket group connect or bind requests. */ 1631 static int audit_multicast_bind(struct net *net, int group) 1632 { 1633 int err = 0; 1634 1635 if (!capable(CAP_AUDIT_READ)) 1636 err = -EPERM; 1637 audit_log_multicast(group, "connect", err); 1638 return err; 1639 } 1640 1641 static void audit_multicast_unbind(struct net *net, int group) 1642 { 1643 audit_log_multicast(group, "disconnect", 0); 1644 } 1645 1646 static int __net_init audit_net_init(struct net *net) 1647 { 1648 struct netlink_kernel_cfg cfg = { 1649 .input = audit_receive, 1650 .bind = audit_multicast_bind, 1651 .unbind = audit_multicast_unbind, 1652 .flags = NL_CFG_F_NONROOT_RECV, 1653 .groups = AUDIT_NLGRP_MAX, 1654 }; 1655 1656 struct audit_net *aunet = net_generic(net, audit_net_id); 1657 1658 aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg); 1659 if (aunet->sk == NULL) { 1660 audit_panic("cannot initialize netlink socket in namespace"); 1661 return -ENOMEM; 1662 } 1663 /* limit the timeout in case auditd is blocked/stopped */ 1664 aunet->sk->sk_sndtimeo = HZ / 10; 1665 1666 return 0; 1667 } 1668 1669 static void __net_exit audit_net_exit(struct net *net) 1670 { 1671 struct audit_net *aunet = net_generic(net, audit_net_id); 1672 1673 /* NOTE: you would think that we would want to check the auditd 1674 * connection and potentially reset it here if it lives in this 1675 * namespace, but since the auditd connection tracking struct holds a 1676 * reference to this namespace (see auditd_set()) we are only ever 1677 * going to get here after that connection has been released */ 1678 1679 netlink_kernel_release(aunet->sk); 1680 } 1681 1682 static struct pernet_operations audit_net_ops __net_initdata = { 1683 .init = audit_net_init, 1684 .exit = audit_net_exit, 1685 .id = &audit_net_id, 1686 .size = sizeof(struct audit_net), 1687 }; 1688 1689 /* Initialize audit support at boot time. */ 1690 static int __init audit_init(void) 1691 { 1692 int i; 1693 1694 if (audit_initialized == AUDIT_DISABLED) 1695 return 0; 1696 1697 audit_buffer_cache = KMEM_CACHE(audit_buffer, SLAB_PANIC); 1698 1699 skb_queue_head_init(&audit_queue); 1700 skb_queue_head_init(&audit_retry_queue); 1701 skb_queue_head_init(&audit_hold_queue); 1702 1703 for (i = 0; i < AUDIT_INODE_BUCKETS; i++) 1704 INIT_LIST_HEAD(&audit_inode_hash[i]); 1705 1706 mutex_init(&audit_cmd_mutex.lock); 1707 audit_cmd_mutex.owner = NULL; 1708 1709 pr_info("initializing netlink subsys (%s)\n", 1710 str_enabled_disabled(audit_default)); 1711 register_pernet_subsys(&audit_net_ops); 1712 1713 audit_initialized = AUDIT_INITIALIZED; 1714 1715 kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); 1716 if (IS_ERR(kauditd_task)) { 1717 int err = PTR_ERR(kauditd_task); 1718 panic("audit: failed to start the kauditd thread (%d)\n", err); 1719 } 1720 1721 audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, 1722 "state=initialized audit_enabled=%u res=1", 1723 audit_enabled); 1724 1725 return 0; 1726 } 1727 postcore_initcall(audit_init); 1728 1729 /* 1730 * Process kernel command-line parameter at boot time. 1731 * audit={0|off} or audit={1|on}. 1732 */ 1733 static int __init audit_enable(char *str) 1734 { 1735 if (!strcasecmp(str, "off") || !strcmp(str, "0")) 1736 audit_default = AUDIT_OFF; 1737 else if (!strcasecmp(str, "on") || !strcmp(str, "1")) 1738 audit_default = AUDIT_ON; 1739 else { 1740 pr_err("audit: invalid 'audit' parameter value (%s)\n", str); 1741 audit_default = AUDIT_ON; 1742 } 1743 1744 if (audit_default == AUDIT_OFF) 1745 audit_initialized = AUDIT_DISABLED; 1746 if (audit_set_enabled(audit_default)) 1747 pr_err("audit: error setting audit state (%d)\n", 1748 audit_default); 1749 1750 pr_info("%s\n", audit_default ? 1751 "enabled (after initialization)" : "disabled (until reboot)"); 1752 1753 return 1; 1754 } 1755 __setup("audit=", audit_enable); 1756 1757 /* Process kernel command-line parameter at boot time. 1758 * audit_backlog_limit=<n> */ 1759 static int __init audit_backlog_limit_set(char *str) 1760 { 1761 u32 audit_backlog_limit_arg; 1762 1763 pr_info("audit_backlog_limit: "); 1764 if (kstrtouint(str, 0, &audit_backlog_limit_arg)) { 1765 pr_cont("using default of %u, unable to parse %s\n", 1766 audit_backlog_limit, str); 1767 return 1; 1768 } 1769 1770 audit_backlog_limit = audit_backlog_limit_arg; 1771 pr_cont("%d\n", audit_backlog_limit); 1772 1773 return 1; 1774 } 1775 __setup("audit_backlog_limit=", audit_backlog_limit_set); 1776 1777 static void audit_buffer_free(struct audit_buffer *ab) 1778 { 1779 if (!ab) 1780 return; 1781 1782 kfree_skb(ab->skb); 1783 kmem_cache_free(audit_buffer_cache, ab); 1784 } 1785 1786 static struct audit_buffer *audit_buffer_alloc(struct audit_context *ctx, 1787 gfp_t gfp_mask, int type) 1788 { 1789 struct audit_buffer *ab; 1790 1791 ab = kmem_cache_alloc(audit_buffer_cache, gfp_mask); 1792 if (!ab) 1793 return NULL; 1794 1795 ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); 1796 if (!ab->skb) 1797 goto err; 1798 if (!nlmsg_put(ab->skb, 0, 0, type, 0, 0)) 1799 goto err; 1800 1801 ab->ctx = ctx; 1802 ab->gfp_mask = gfp_mask; 1803 1804 return ab; 1805 1806 err: 1807 audit_buffer_free(ab); 1808 return NULL; 1809 } 1810 1811 /** 1812 * audit_serial - compute a serial number for the audit record 1813 * 1814 * Compute a serial number for the audit record. Audit records are 1815 * written to user-space as soon as they are generated, so a complete 1816 * audit record may be written in several pieces. The timestamp of the 1817 * record and this serial number are used by the user-space tools to 1818 * determine which pieces belong to the same audit record. The 1819 * (timestamp,serial) tuple is unique for each syscall and is live from 1820 * syscall entry to syscall exit. 1821 * 1822 * NOTE: Another possibility is to store the formatted records off the 1823 * audit context (for those records that have a context), and emit them 1824 * all at syscall exit. However, this could delay the reporting of 1825 * significant errors until syscall exit (or never, if the system 1826 * halts). 1827 */ 1828 unsigned int audit_serial(void) 1829 { 1830 static atomic_t serial = ATOMIC_INIT(0); 1831 1832 return atomic_inc_return(&serial); 1833 } 1834 1835 static inline void audit_get_stamp(struct audit_context *ctx, 1836 struct timespec64 *t, unsigned int *serial) 1837 { 1838 if (!ctx || !auditsc_get_stamp(ctx, t, serial)) { 1839 ktime_get_coarse_real_ts64(t); 1840 *serial = audit_serial(); 1841 } 1842 } 1843 1844 /** 1845 * audit_log_start - obtain an audit buffer 1846 * @ctx: audit_context (may be NULL) 1847 * @gfp_mask: type of allocation 1848 * @type: audit message type 1849 * 1850 * Returns audit_buffer pointer on success or NULL on error. 1851 * 1852 * Obtain an audit buffer. This routine does locking to obtain the 1853 * audit buffer, but then no locking is required for calls to 1854 * audit_log_*format. If the task (ctx) is a task that is currently in a 1855 * syscall, then the syscall is marked as auditable and an audit record 1856 * will be written at syscall exit. If there is no associated task, then 1857 * task context (ctx) should be NULL. 1858 */ 1859 struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, 1860 int type) 1861 { 1862 struct audit_buffer *ab; 1863 struct timespec64 t; 1864 unsigned int serial; 1865 1866 if (audit_initialized != AUDIT_INITIALIZED) 1867 return NULL; 1868 1869 if (unlikely(!audit_filter(type, AUDIT_FILTER_EXCLUDE))) 1870 return NULL; 1871 1872 /* NOTE: don't ever fail/sleep on these two conditions: 1873 * 1. auditd generated record - since we need auditd to drain the 1874 * queue; also, when we are checking for auditd, compare PIDs using 1875 * task_tgid_vnr() since auditd_pid is set in audit_receive_msg() 1876 * using a PID anchored in the caller's namespace 1877 * 2. generator holding the audit_cmd_mutex - we don't want to block 1878 * while holding the mutex, although we do penalize the sender 1879 * later in audit_receive() when it is safe to block 1880 */ 1881 if (!(auditd_test_task(current) || audit_ctl_owner_current())) { 1882 long stime = audit_backlog_wait_time; 1883 1884 while (audit_backlog_limit && 1885 (skb_queue_len(&audit_queue) > audit_backlog_limit)) { 1886 /* wake kauditd to try and flush the queue */ 1887 wake_up_interruptible(&kauditd_wait); 1888 1889 /* sleep if we are allowed and we haven't exhausted our 1890 * backlog wait limit */ 1891 if (gfpflags_allow_blocking(gfp_mask) && (stime > 0)) { 1892 long rtime = stime; 1893 1894 DECLARE_WAITQUEUE(wait, current); 1895 1896 add_wait_queue_exclusive(&audit_backlog_wait, 1897 &wait); 1898 set_current_state(TASK_UNINTERRUPTIBLE); 1899 stime = schedule_timeout(rtime); 1900 atomic_add(rtime - stime, &audit_backlog_wait_time_actual); 1901 remove_wait_queue(&audit_backlog_wait, &wait); 1902 } else { 1903 if (audit_rate_check() && printk_ratelimit()) 1904 pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n", 1905 skb_queue_len(&audit_queue), 1906 audit_backlog_limit); 1907 audit_log_lost("backlog limit exceeded"); 1908 return NULL; 1909 } 1910 } 1911 } 1912 1913 ab = audit_buffer_alloc(ctx, gfp_mask, type); 1914 if (!ab) { 1915 audit_log_lost("out of memory in audit_log_start"); 1916 return NULL; 1917 } 1918 1919 audit_get_stamp(ab->ctx, &t, &serial); 1920 /* cancel dummy context to enable supporting records */ 1921 if (ctx) 1922 ctx->dummy = 0; 1923 audit_log_format(ab, "audit(%llu.%03lu:%u): ", 1924 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial); 1925 1926 return ab; 1927 } 1928 1929 /** 1930 * audit_expand - expand skb in the audit buffer 1931 * @ab: audit_buffer 1932 * @extra: space to add at tail of the skb 1933 * 1934 * Returns 0 (no space) on failed expansion, or available space if 1935 * successful. 1936 */ 1937 static inline int audit_expand(struct audit_buffer *ab, int extra) 1938 { 1939 struct sk_buff *skb = ab->skb; 1940 int oldtail = skb_tailroom(skb); 1941 int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask); 1942 int newtail = skb_tailroom(skb); 1943 1944 if (ret < 0) { 1945 audit_log_lost("out of memory in audit_expand"); 1946 return 0; 1947 } 1948 1949 skb->truesize += newtail - oldtail; 1950 return newtail; 1951 } 1952 1953 /* 1954 * Format an audit message into the audit buffer. If there isn't enough 1955 * room in the audit buffer, more room will be allocated and vsnprint 1956 * will be called a second time. Currently, we assume that a printk 1957 * can't format message larger than 1024 bytes, so we don't either. 1958 */ 1959 static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, 1960 va_list args) 1961 { 1962 int len, avail; 1963 struct sk_buff *skb; 1964 va_list args2; 1965 1966 if (!ab) 1967 return; 1968 1969 BUG_ON(!ab->skb); 1970 skb = ab->skb; 1971 avail = skb_tailroom(skb); 1972 if (avail == 0) { 1973 avail = audit_expand(ab, AUDIT_BUFSIZ); 1974 if (!avail) 1975 goto out; 1976 } 1977 va_copy(args2, args); 1978 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args); 1979 if (len >= avail) { 1980 /* The printk buffer is 1024 bytes long, so if we get 1981 * here and AUDIT_BUFSIZ is at least 1024, then we can 1982 * log everything that printk could have logged. */ 1983 avail = audit_expand(ab, 1984 max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); 1985 if (!avail) 1986 goto out_va_end; 1987 len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); 1988 } 1989 if (len > 0) 1990 skb_put(skb, len); 1991 out_va_end: 1992 va_end(args2); 1993 out: 1994 return; 1995 } 1996 1997 /** 1998 * audit_log_format - format a message into the audit buffer. 1999 * @ab: audit_buffer 2000 * @fmt: format string 2001 * @...: optional parameters matching @fmt string 2002 * 2003 * All the work is done in audit_log_vformat. 2004 */ 2005 void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) 2006 { 2007 va_list args; 2008 2009 if (!ab) 2010 return; 2011 va_start(args, fmt); 2012 audit_log_vformat(ab, fmt, args); 2013 va_end(args); 2014 } 2015 2016 /** 2017 * audit_log_n_hex - convert a buffer to hex and append it to the audit skb 2018 * @ab: the audit_buffer 2019 * @buf: buffer to convert to hex 2020 * @len: length of @buf to be converted 2021 * 2022 * No return value; failure to expand is silently ignored. 2023 * 2024 * This function will take the passed buf and convert it into a string of 2025 * ascii hex digits. The new string is placed onto the skb. 2026 */ 2027 void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, 2028 size_t len) 2029 { 2030 int i, avail, new_len; 2031 unsigned char *ptr; 2032 struct sk_buff *skb; 2033 2034 if (!ab) 2035 return; 2036 2037 BUG_ON(!ab->skb); 2038 skb = ab->skb; 2039 avail = skb_tailroom(skb); 2040 new_len = len<<1; 2041 if (new_len >= avail) { 2042 /* Round the buffer request up to the next multiple */ 2043 new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); 2044 avail = audit_expand(ab, new_len); 2045 if (!avail) 2046 return; 2047 } 2048 2049 ptr = skb_tail_pointer(skb); 2050 for (i = 0; i < len; i++) 2051 ptr = hex_byte_pack_upper(ptr, buf[i]); 2052 *ptr = 0; 2053 skb_put(skb, len << 1); /* new string is twice the old string */ 2054 } 2055 2056 /* 2057 * Format a string of no more than slen characters into the audit buffer, 2058 * enclosed in quote marks. 2059 */ 2060 void audit_log_n_string(struct audit_buffer *ab, const char *string, 2061 size_t slen) 2062 { 2063 int avail, new_len; 2064 unsigned char *ptr; 2065 struct sk_buff *skb; 2066 2067 if (!ab) 2068 return; 2069 2070 BUG_ON(!ab->skb); 2071 skb = ab->skb; 2072 avail = skb_tailroom(skb); 2073 new_len = slen + 3; /* enclosing quotes + null terminator */ 2074 if (new_len > avail) { 2075 avail = audit_expand(ab, new_len); 2076 if (!avail) 2077 return; 2078 } 2079 ptr = skb_tail_pointer(skb); 2080 *ptr++ = '"'; 2081 memcpy(ptr, string, slen); 2082 ptr += slen; 2083 *ptr++ = '"'; 2084 *ptr = 0; 2085 skb_put(skb, slen + 2); /* don't include null terminator */ 2086 } 2087 2088 /** 2089 * audit_string_contains_control - does a string need to be logged in hex 2090 * @string: string to be checked 2091 * @len: max length of the string to check 2092 */ 2093 bool audit_string_contains_control(const char *string, size_t len) 2094 { 2095 const unsigned char *p; 2096 for (p = string; p < (const unsigned char *)string + len; p++) { 2097 if (*p == '"' || *p < 0x21 || *p > 0x7e) 2098 return true; 2099 } 2100 return false; 2101 } 2102 2103 /** 2104 * audit_log_n_untrustedstring - log a string that may contain random characters 2105 * @ab: audit_buffer 2106 * @string: string to be logged 2107 * @len: length of string (not including trailing null) 2108 * 2109 * This code will escape a string that is passed to it if the string 2110 * contains a control character, unprintable character, double quote mark, 2111 * or a space. Unescaped strings will start and end with a double quote mark. 2112 * Strings that are escaped are printed in hex (2 digits per char). 2113 * 2114 * The caller specifies the number of characters in the string to log, which may 2115 * or may not be the entire string. 2116 */ 2117 void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string, 2118 size_t len) 2119 { 2120 if (audit_string_contains_control(string, len)) 2121 audit_log_n_hex(ab, string, len); 2122 else 2123 audit_log_n_string(ab, string, len); 2124 } 2125 2126 /** 2127 * audit_log_untrustedstring - log a string that may contain random characters 2128 * @ab: audit_buffer 2129 * @string: string to be logged 2130 * 2131 * Same as audit_log_n_untrustedstring(), except that strlen is used to 2132 * determine string length. 2133 */ 2134 void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) 2135 { 2136 audit_log_n_untrustedstring(ab, string, strlen(string)); 2137 } 2138 2139 /* This is a helper-function to print the escaped d_path */ 2140 void audit_log_d_path(struct audit_buffer *ab, const char *prefix, 2141 const struct path *path) 2142 { 2143 char *p, *pathname; 2144 2145 if (prefix) 2146 audit_log_format(ab, "%s", prefix); 2147 2148 /* We will allow 11 spaces for ' (deleted)' to be appended */ 2149 pathname = kmalloc(PATH_MAX+11, ab->gfp_mask); 2150 if (!pathname) { 2151 audit_log_format(ab, "\"<no_memory>\""); 2152 return; 2153 } 2154 p = d_path(path, pathname, PATH_MAX+11); 2155 if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ 2156 /* FIXME: can we save some information here? */ 2157 audit_log_format(ab, "\"<too_long>\""); 2158 } else 2159 audit_log_untrustedstring(ab, p); 2160 kfree(pathname); 2161 } 2162 2163 void audit_log_session_info(struct audit_buffer *ab) 2164 { 2165 unsigned int sessionid = audit_get_sessionid(current); 2166 uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current)); 2167 2168 audit_log_format(ab, "auid=%u ses=%u", auid, sessionid); 2169 } 2170 2171 void audit_log_key(struct audit_buffer *ab, char *key) 2172 { 2173 audit_log_format(ab, " key="); 2174 if (key) 2175 audit_log_untrustedstring(ab, key); 2176 else 2177 audit_log_format(ab, "(null)"); 2178 } 2179 2180 int audit_log_task_context(struct audit_buffer *ab) 2181 { 2182 struct lsm_prop prop; 2183 char *ctx = NULL; 2184 unsigned len; 2185 int error; 2186 2187 security_current_getlsmprop_subj(&prop); 2188 if (!lsmprop_is_set(&prop)) 2189 return 0; 2190 2191 error = security_lsmprop_to_secctx(&prop, &ctx, &len); 2192 if (error) { 2193 if (error != -EINVAL) 2194 goto error_path; 2195 return 0; 2196 } 2197 2198 audit_log_format(ab, " subj=%s", ctx); 2199 security_release_secctx(ctx, len); 2200 return 0; 2201 2202 error_path: 2203 audit_panic("error in audit_log_task_context"); 2204 return error; 2205 } 2206 EXPORT_SYMBOL(audit_log_task_context); 2207 2208 void audit_log_d_path_exe(struct audit_buffer *ab, 2209 struct mm_struct *mm) 2210 { 2211 struct file *exe_file; 2212 2213 if (!mm) 2214 goto out_null; 2215 2216 exe_file = get_mm_exe_file(mm); 2217 if (!exe_file) 2218 goto out_null; 2219 2220 audit_log_d_path(ab, " exe=", &exe_file->f_path); 2221 fput(exe_file); 2222 return; 2223 out_null: 2224 audit_log_format(ab, " exe=(null)"); 2225 } 2226 2227 struct tty_struct *audit_get_tty(void) 2228 { 2229 struct tty_struct *tty = NULL; 2230 unsigned long flags; 2231 2232 spin_lock_irqsave(¤t->sighand->siglock, flags); 2233 if (current->signal) 2234 tty = tty_kref_get(current->signal->tty); 2235 spin_unlock_irqrestore(¤t->sighand->siglock, flags); 2236 return tty; 2237 } 2238 2239 void audit_put_tty(struct tty_struct *tty) 2240 { 2241 tty_kref_put(tty); 2242 } 2243 2244 void audit_log_task_info(struct audit_buffer *ab) 2245 { 2246 const struct cred *cred; 2247 char comm[sizeof(current->comm)]; 2248 struct tty_struct *tty; 2249 2250 if (!ab) 2251 return; 2252 2253 cred = current_cred(); 2254 tty = audit_get_tty(); 2255 audit_log_format(ab, 2256 " ppid=%d pid=%d auid=%u uid=%u gid=%u" 2257 " euid=%u suid=%u fsuid=%u" 2258 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u", 2259 task_ppid_nr(current), 2260 task_tgid_nr(current), 2261 from_kuid(&init_user_ns, audit_get_loginuid(current)), 2262 from_kuid(&init_user_ns, cred->uid), 2263 from_kgid(&init_user_ns, cred->gid), 2264 from_kuid(&init_user_ns, cred->euid), 2265 from_kuid(&init_user_ns, cred->suid), 2266 from_kuid(&init_user_ns, cred->fsuid), 2267 from_kgid(&init_user_ns, cred->egid), 2268 from_kgid(&init_user_ns, cred->sgid), 2269 from_kgid(&init_user_ns, cred->fsgid), 2270 tty ? tty_name(tty) : "(none)", 2271 audit_get_sessionid(current)); 2272 audit_put_tty(tty); 2273 audit_log_format(ab, " comm="); 2274 audit_log_untrustedstring(ab, get_task_comm(comm, current)); 2275 audit_log_d_path_exe(ab, current->mm); 2276 audit_log_task_context(ab); 2277 } 2278 EXPORT_SYMBOL(audit_log_task_info); 2279 2280 /** 2281 * audit_log_path_denied - report a path restriction denial 2282 * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc) 2283 * @operation: specific operation name 2284 */ 2285 void audit_log_path_denied(int type, const char *operation) 2286 { 2287 struct audit_buffer *ab; 2288 2289 if (!audit_enabled || audit_dummy_context()) 2290 return; 2291 2292 /* Generate log with subject, operation, outcome. */ 2293 ab = audit_log_start(audit_context(), GFP_KERNEL, type); 2294 if (!ab) 2295 return; 2296 audit_log_format(ab, "op=%s", operation); 2297 audit_log_task_info(ab); 2298 audit_log_format(ab, " res=0"); 2299 audit_log_end(ab); 2300 } 2301 2302 /* global counter which is incremented every time something logs in */ 2303 static atomic_t session_id = ATOMIC_INIT(0); 2304 2305 static int audit_set_loginuid_perm(kuid_t loginuid) 2306 { 2307 /* if we are unset, we don't need privs */ 2308 if (!audit_loginuid_set(current)) 2309 return 0; 2310 /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/ 2311 if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE)) 2312 return -EPERM; 2313 /* it is set, you need permission */ 2314 if (!capable(CAP_AUDIT_CONTROL)) 2315 return -EPERM; 2316 /* reject if this is not an unset and we don't allow that */ 2317 if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID) 2318 && uid_valid(loginuid)) 2319 return -EPERM; 2320 return 0; 2321 } 2322 2323 static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid, 2324 unsigned int oldsessionid, 2325 unsigned int sessionid, int rc) 2326 { 2327 struct audit_buffer *ab; 2328 uid_t uid, oldloginuid, loginuid; 2329 struct tty_struct *tty; 2330 2331 if (!audit_enabled) 2332 return; 2333 2334 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_LOGIN); 2335 if (!ab) 2336 return; 2337 2338 uid = from_kuid(&init_user_ns, task_uid(current)); 2339 oldloginuid = from_kuid(&init_user_ns, koldloginuid); 2340 loginuid = from_kuid(&init_user_ns, kloginuid); 2341 tty = audit_get_tty(); 2342 2343 audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid); 2344 audit_log_task_context(ab); 2345 audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d", 2346 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)", 2347 oldsessionid, sessionid, !rc); 2348 audit_put_tty(tty); 2349 audit_log_end(ab); 2350 } 2351 2352 /** 2353 * audit_set_loginuid - set current task's loginuid 2354 * @loginuid: loginuid value 2355 * 2356 * Returns 0. 2357 * 2358 * Called (set) from fs/proc/base.c::proc_loginuid_write(). 2359 */ 2360 int audit_set_loginuid(kuid_t loginuid) 2361 { 2362 unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET; 2363 kuid_t oldloginuid; 2364 int rc; 2365 2366 oldloginuid = audit_get_loginuid(current); 2367 oldsessionid = audit_get_sessionid(current); 2368 2369 rc = audit_set_loginuid_perm(loginuid); 2370 if (rc) 2371 goto out; 2372 2373 /* are we setting or clearing? */ 2374 if (uid_valid(loginuid)) { 2375 sessionid = (unsigned int)atomic_inc_return(&session_id); 2376 if (unlikely(sessionid == AUDIT_SID_UNSET)) 2377 sessionid = (unsigned int)atomic_inc_return(&session_id); 2378 } 2379 2380 current->sessionid = sessionid; 2381 current->loginuid = loginuid; 2382 out: 2383 audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc); 2384 return rc; 2385 } 2386 2387 /** 2388 * audit_signal_info - record signal info for shutting down audit subsystem 2389 * @sig: signal value 2390 * @t: task being signaled 2391 * 2392 * If the audit subsystem is being terminated, record the task (pid) 2393 * and uid that is doing that. 2394 */ 2395 int audit_signal_info(int sig, struct task_struct *t) 2396 { 2397 kuid_t uid = current_uid(), auid; 2398 2399 if (auditd_test_task(t) && 2400 (sig == SIGTERM || sig == SIGHUP || 2401 sig == SIGUSR1 || sig == SIGUSR2)) { 2402 audit_sig_pid = task_tgid_nr(current); 2403 auid = audit_get_loginuid(current); 2404 if (uid_valid(auid)) 2405 audit_sig_uid = auid; 2406 else 2407 audit_sig_uid = uid; 2408 security_current_getlsmprop_subj(&audit_sig_lsm); 2409 } 2410 2411 return audit_signal_info_syscall(t); 2412 } 2413 2414 /** 2415 * audit_log_end - end one audit record 2416 * @ab: the audit_buffer 2417 * 2418 * We can not do a netlink send inside an irq context because it blocks (last 2419 * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a 2420 * queue and a kthread is scheduled to remove them from the queue outside the 2421 * irq context. May be called in any context. 2422 */ 2423 void audit_log_end(struct audit_buffer *ab) 2424 { 2425 struct sk_buff *skb; 2426 struct nlmsghdr *nlh; 2427 2428 if (!ab) 2429 return; 2430 2431 if (audit_rate_check()) { 2432 skb = ab->skb; 2433 ab->skb = NULL; 2434 2435 /* setup the netlink header, see the comments in 2436 * kauditd_send_multicast_skb() for length quirks */ 2437 nlh = nlmsg_hdr(skb); 2438 nlh->nlmsg_len = skb->len - NLMSG_HDRLEN; 2439 2440 /* queue the netlink packet and poke the kauditd thread */ 2441 skb_queue_tail(&audit_queue, skb); 2442 wake_up_interruptible(&kauditd_wait); 2443 } else 2444 audit_log_lost("rate limit exceeded"); 2445 2446 audit_buffer_free(ab); 2447 } 2448 2449 /** 2450 * audit_log - Log an audit record 2451 * @ctx: audit context 2452 * @gfp_mask: type of allocation 2453 * @type: audit message type 2454 * @fmt: format string to use 2455 * @...: variable parameters matching the format string 2456 * 2457 * This is a convenience function that calls audit_log_start, 2458 * audit_log_vformat, and audit_log_end. It may be called 2459 * in any context. 2460 */ 2461 void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, 2462 const char *fmt, ...) 2463 { 2464 struct audit_buffer *ab; 2465 va_list args; 2466 2467 ab = audit_log_start(ctx, gfp_mask, type); 2468 if (ab) { 2469 va_start(args, fmt); 2470 audit_log_vformat(ab, fmt, args); 2471 va_end(args); 2472 audit_log_end(ab); 2473 } 2474 } 2475 2476 EXPORT_SYMBOL(audit_log_start); 2477 EXPORT_SYMBOL(audit_log_end); 2478 EXPORT_SYMBOL(audit_log_format); 2479 EXPORT_SYMBOL(audit_log); 2480