| 1 | /* audit.c -- Auditing support |
| 2 | * Gateway between the kernel (e.g., selinux) and the user-space audit daemon. |
| 3 | * System-call specific features have moved to auditsc.c |
| 4 | * |
| 5 | * Copyright 2003-2007 Red Hat Inc., Durham, North Carolina. |
| 6 | * All Rights Reserved. |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License as published by |
| 10 | * the Free Software Foundation; either version 2 of the License, or |
| 11 | * (at your option) any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU General Public License |
| 19 | * along with this program; if not, write to the Free Software |
| 20 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 21 | * |
| 22 | * Written by Rickard E. (Rik) Faith <faith@redhat.com> |
| 23 | * |
| 24 | * Goals: 1) Integrate fully with Security Modules. |
| 25 | * 2) Minimal run-time overhead: |
| 26 | * a) Minimal when syscall auditing is disabled (audit_enable=0). |
| 27 | * b) Small when syscall auditing is enabled and no audit record |
| 28 | * is generated (defer as much work as possible to record |
| 29 | * generation time): |
| 30 | * i) context is allocated, |
| 31 | * ii) names from getname are stored without a copy, and |
| 32 | * iii) inode information stored from path_lookup. |
| 33 | * 3) Ability to disable syscall auditing at boot time (audit=0). |
| 34 | * 4) Usable by other parts of the kernel (if audit_log* is called, |
| 35 | * then a syscall record will be generated automatically for the |
| 36 | * current syscall). |
| 37 | * 5) Netlink interface to user-space. |
| 38 | * 6) Support low-overhead kernel-based filtering to minimize the |
| 39 | * information that must be passed to user-space. |
| 40 | * |
| 41 | * Example user-space utilities: http://people.redhat.com/sgrubb/audit/ |
| 42 | */ |
| 43 | |
| 44 | #include <linux/init.h> |
| 45 | #include <asm/types.h> |
| 46 | #include <asm/atomic.h> |
| 47 | #include <linux/mm.h> |
| 48 | #include <linux/module.h> |
| 49 | #include <linux/slab.h> |
| 50 | #include <linux/err.h> |
| 51 | #include <linux/kthread.h> |
| 52 | |
| 53 | #include <linux/audit.h> |
| 54 | |
| 55 | #include <net/sock.h> |
| 56 | #include <net/netlink.h> |
| 57 | #include <linux/skbuff.h> |
| 58 | #include <linux/netlink.h> |
| 59 | #include <linux/freezer.h> |
| 60 | #include <linux/tty.h> |
| 61 | |
| 62 | #include "audit.h" |
| 63 | |
| 64 | /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED. |
| 65 | * (Initialization happens after skb_init is called.) */ |
| 66 | #define AUDIT_DISABLED -1 |
| 67 | #define AUDIT_UNINITIALIZED 0 |
| 68 | #define AUDIT_INITIALIZED 1 |
| 69 | static int audit_initialized; |
| 70 | |
| 71 | #define AUDIT_OFF 0 |
| 72 | #define AUDIT_ON 1 |
| 73 | #define AUDIT_LOCKED 2 |
| 74 | int audit_enabled; |
| 75 | int audit_ever_enabled; |
| 76 | |
| 77 | EXPORT_SYMBOL_GPL(audit_enabled); |
| 78 | |
| 79 | /* Default state when kernel boots without any parameters. */ |
| 80 | static int audit_default; |
| 81 | |
| 82 | /* If auditing cannot proceed, audit_failure selects what happens. */ |
| 83 | static int audit_failure = AUDIT_FAIL_PRINTK; |
| 84 | |
| 85 | /* |
| 86 | * If audit records are to be written to the netlink socket, audit_pid |
| 87 | * contains the pid of the auditd process and audit_nlk_pid contains |
| 88 | * the pid to use to send netlink messages to that process. |
| 89 | */ |
| 90 | int audit_pid; |
| 91 | static int audit_nlk_pid; |
| 92 | |
| 93 | /* If audit_rate_limit is non-zero, limit the rate of sending audit records |
| 94 | * to that number per second. This prevents DoS attacks, but results in |
| 95 | * audit records being dropped. */ |
| 96 | static int audit_rate_limit; |
| 97 | |
| 98 | /* Number of outstanding audit_buffers allowed. */ |
| 99 | static int audit_backlog_limit = 64; |
| 100 | static int audit_backlog_wait_time = 60 * HZ; |
| 101 | static int audit_backlog_wait_overflow = 0; |
| 102 | |
| 103 | /* The identity of the user shutting down the audit system. */ |
| 104 | uid_t audit_sig_uid = -1; |
| 105 | pid_t audit_sig_pid = -1; |
| 106 | u32 audit_sig_sid = 0; |
| 107 | |
| 108 | /* Records can be lost in several ways: |
| 109 | 0) [suppressed in audit_alloc] |
| 110 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] |
| 111 | 2) out of memory in audit_log_move [alloc_skb] |
| 112 | 3) suppressed due to audit_rate_limit |
| 113 | 4) suppressed due to audit_backlog_limit |
| 114 | */ |
| 115 | static atomic_t audit_lost = ATOMIC_INIT(0); |
| 116 | |
| 117 | /* The netlink socket. */ |
| 118 | static struct sock *audit_sock; |
| 119 | |
| 120 | /* Hash for inode-based rules */ |
| 121 | struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; |
| 122 | |
| 123 | /* The audit_freelist is a list of pre-allocated audit buffers (if more |
| 124 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of |
| 125 | * being placed on the freelist). */ |
| 126 | static DEFINE_SPINLOCK(audit_freelist_lock); |
| 127 | static int audit_freelist_count; |
| 128 | static LIST_HEAD(audit_freelist); |
| 129 | |
| 130 | static struct sk_buff_head audit_skb_queue; |
| 131 | /* queue of skbs to send to auditd when/if it comes back */ |
| 132 | static struct sk_buff_head audit_skb_hold_queue; |
| 133 | static struct task_struct *kauditd_task; |
| 134 | static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); |
| 135 | static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); |
| 136 | |
| 137 | /* Serialize requests from userspace. */ |
| 138 | DEFINE_MUTEX(audit_cmd_mutex); |
| 139 | |
| 140 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting |
| 141 | * audit records. Since printk uses a 1024 byte buffer, this buffer |
| 142 | * should be at least that large. */ |
| 143 | #define AUDIT_BUFSIZ 1024 |
| 144 | |
| 145 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the |
| 146 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ |
| 147 | #define AUDIT_MAXFREE (2*NR_CPUS) |
| 148 | |
| 149 | /* The audit_buffer is used when formatting an audit record. The caller |
| 150 | * locks briefly to get the record off the freelist or to allocate the |
| 151 | * buffer, and locks briefly to send the buffer to the netlink layer or |
| 152 | * to place it on a transmit queue. Multiple audit_buffers can be in |
| 153 | * use simultaneously. */ |
| 154 | struct audit_buffer { |
| 155 | struct list_head list; |
| 156 | struct sk_buff *skb; /* formatted skb ready to send */ |
| 157 | struct audit_context *ctx; /* NULL or associated context */ |
| 158 | gfp_t gfp_mask; |
| 159 | }; |
| 160 | |
| 161 | struct audit_reply { |
| 162 | int pid; |
| 163 | struct sk_buff *skb; |
| 164 | }; |
| 165 | |
| 166 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
| 167 | { |
| 168 | if (ab) { |
| 169 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); |
| 170 | nlh->nlmsg_pid = pid; |
| 171 | } |
| 172 | } |
| 173 | |
| 174 | void audit_panic(const char *message) |
| 175 | { |
| 176 | switch (audit_failure) |
| 177 | { |
| 178 | case AUDIT_FAIL_SILENT: |
| 179 | break; |
| 180 | case AUDIT_FAIL_PRINTK: |
| 181 | if (printk_ratelimit()) |
| 182 | printk(KERN_ERR "audit: %s\n", message); |
| 183 | break; |
| 184 | case AUDIT_FAIL_PANIC: |
| 185 | /* test audit_pid since printk is always losey, why bother? */ |
| 186 | if (audit_pid) |
| 187 | panic("audit: %s\n", message); |
| 188 | break; |
| 189 | } |
| 190 | } |
| 191 | |
| 192 | static inline int audit_rate_check(void) |
| 193 | { |
| 194 | static unsigned long last_check = 0; |
| 195 | static int messages = 0; |
| 196 | static DEFINE_SPINLOCK(lock); |
| 197 | unsigned long flags; |
| 198 | unsigned long now; |
| 199 | unsigned long elapsed; |
| 200 | int retval = 0; |
| 201 | |
| 202 | if (!audit_rate_limit) return 1; |
| 203 | |
| 204 | spin_lock_irqsave(&lock, flags); |
| 205 | if (++messages < audit_rate_limit) { |
| 206 | retval = 1; |
| 207 | } else { |
| 208 | now = jiffies; |
| 209 | elapsed = now - last_check; |
| 210 | if (elapsed > HZ) { |
| 211 | last_check = now; |
| 212 | messages = 0; |
| 213 | retval = 1; |
| 214 | } |
| 215 | } |
| 216 | spin_unlock_irqrestore(&lock, flags); |
| 217 | |
| 218 | return retval; |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * audit_log_lost - conditionally log lost audit message event |
| 223 | * @message: the message stating reason for lost audit message |
| 224 | * |
| 225 | * Emit at least 1 message per second, even if audit_rate_check is |
| 226 | * throttling. |
| 227 | * Always increment the lost messages counter. |
| 228 | */ |
| 229 | void audit_log_lost(const char *message) |
| 230 | { |
| 231 | static unsigned long last_msg = 0; |
| 232 | static DEFINE_SPINLOCK(lock); |
| 233 | unsigned long flags; |
| 234 | unsigned long now; |
| 235 | int print; |
| 236 | |
| 237 | atomic_inc(&audit_lost); |
| 238 | |
| 239 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); |
| 240 | |
| 241 | if (!print) { |
| 242 | spin_lock_irqsave(&lock, flags); |
| 243 | now = jiffies; |
| 244 | if (now - last_msg > HZ) { |
| 245 | print = 1; |
| 246 | last_msg = now; |
| 247 | } |
| 248 | spin_unlock_irqrestore(&lock, flags); |
| 249 | } |
| 250 | |
| 251 | if (print) { |
| 252 | if (printk_ratelimit()) |
| 253 | printk(KERN_WARNING |
| 254 | "audit: audit_lost=%d audit_rate_limit=%d " |
| 255 | "audit_backlog_limit=%d\n", |
| 256 | atomic_read(&audit_lost), |
| 257 | audit_rate_limit, |
| 258 | audit_backlog_limit); |
| 259 | audit_panic(message); |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | static int audit_log_config_change(char *function_name, int new, int old, |
| 264 | uid_t loginuid, u32 sessionid, u32 sid, |
| 265 | int allow_changes) |
| 266 | { |
| 267 | struct audit_buffer *ab; |
| 268 | int rc = 0; |
| 269 | |
| 270 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); |
| 271 | audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new, |
| 272 | old, loginuid, sessionid); |
| 273 | if (sid) { |
| 274 | char *ctx = NULL; |
| 275 | u32 len; |
| 276 | |
| 277 | rc = security_secid_to_secctx(sid, &ctx, &len); |
| 278 | if (rc) { |
| 279 | audit_log_format(ab, " sid=%u", sid); |
| 280 | allow_changes = 0; /* Something weird, deny request */ |
| 281 | } else { |
| 282 | audit_log_format(ab, " subj=%s", ctx); |
| 283 | security_release_secctx(ctx, len); |
| 284 | } |
| 285 | } |
| 286 | audit_log_format(ab, " res=%d", allow_changes); |
| 287 | audit_log_end(ab); |
| 288 | return rc; |
| 289 | } |
| 290 | |
| 291 | static int audit_do_config_change(char *function_name, int *to_change, |
| 292 | int new, uid_t loginuid, u32 sessionid, |
| 293 | u32 sid) |
| 294 | { |
| 295 | int allow_changes, rc = 0, old = *to_change; |
| 296 | |
| 297 | /* check if we are locked */ |
| 298 | if (audit_enabled == AUDIT_LOCKED) |
| 299 | allow_changes = 0; |
| 300 | else |
| 301 | allow_changes = 1; |
| 302 | |
| 303 | if (audit_enabled != AUDIT_OFF) { |
| 304 | rc = audit_log_config_change(function_name, new, old, loginuid, |
| 305 | sessionid, sid, allow_changes); |
| 306 | if (rc) |
| 307 | allow_changes = 0; |
| 308 | } |
| 309 | |
| 310 | /* If we are allowed, make the change */ |
| 311 | if (allow_changes == 1) |
| 312 | *to_change = new; |
| 313 | /* Not allowed, update reason */ |
| 314 | else if (rc == 0) |
| 315 | rc = -EPERM; |
| 316 | return rc; |
| 317 | } |
| 318 | |
| 319 | static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid, |
| 320 | u32 sid) |
| 321 | { |
| 322 | return audit_do_config_change("audit_rate_limit", &audit_rate_limit, |
| 323 | limit, loginuid, sessionid, sid); |
| 324 | } |
| 325 | |
| 326 | static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid, |
| 327 | u32 sid) |
| 328 | { |
| 329 | return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, |
| 330 | limit, loginuid, sessionid, sid); |
| 331 | } |
| 332 | |
| 333 | static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid) |
| 334 | { |
| 335 | int rc; |
| 336 | if (state < AUDIT_OFF || state > AUDIT_LOCKED) |
| 337 | return -EINVAL; |
| 338 | |
| 339 | rc = audit_do_config_change("audit_enabled", &audit_enabled, state, |
| 340 | loginuid, sessionid, sid); |
| 341 | |
| 342 | if (!rc) |
| 343 | audit_ever_enabled |= !!state; |
| 344 | |
| 345 | return rc; |
| 346 | } |
| 347 | |
| 348 | static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid) |
| 349 | { |
| 350 | if (state != AUDIT_FAIL_SILENT |
| 351 | && state != AUDIT_FAIL_PRINTK |
| 352 | && state != AUDIT_FAIL_PANIC) |
| 353 | return -EINVAL; |
| 354 | |
| 355 | return audit_do_config_change("audit_failure", &audit_failure, state, |
| 356 | loginuid, sessionid, sid); |
| 357 | } |
| 358 | |
| 359 | /* |
| 360 | * Queue skbs to be sent to auditd when/if it comes back. These skbs should |
| 361 | * already have been sent via prink/syslog and so if these messages are dropped |
| 362 | * it is not a huge concern since we already passed the audit_log_lost() |
| 363 | * notification and stuff. This is just nice to get audit messages during |
| 364 | * boot before auditd is running or messages generated while auditd is stopped. |
| 365 | * This only holds messages is audit_default is set, aka booting with audit=1 |
| 366 | * or building your kernel that way. |
| 367 | */ |
| 368 | static void audit_hold_skb(struct sk_buff *skb) |
| 369 | { |
| 370 | if (audit_default && |
| 371 | skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit) |
| 372 | skb_queue_tail(&audit_skb_hold_queue, skb); |
| 373 | else |
| 374 | kfree_skb(skb); |
| 375 | } |
| 376 | |
| 377 | /* |
| 378 | * For one reason or another this nlh isn't getting delivered to the userspace |
| 379 | * audit daemon, just send it to printk. |
| 380 | */ |
| 381 | static void audit_printk_skb(struct sk_buff *skb) |
| 382 | { |
| 383 | struct nlmsghdr *nlh = nlmsg_hdr(skb); |
| 384 | char *data = NLMSG_DATA(nlh); |
| 385 | |
| 386 | if (nlh->nlmsg_type != AUDIT_EOE) { |
| 387 | if (printk_ratelimit()) |
| 388 | printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data); |
| 389 | else |
| 390 | audit_log_lost("printk limit exceeded\n"); |
| 391 | } |
| 392 | |
| 393 | audit_hold_skb(skb); |
| 394 | } |
| 395 | |
| 396 | static void kauditd_send_skb(struct sk_buff *skb) |
| 397 | { |
| 398 | int err; |
| 399 | /* take a reference in case we can't send it and we want to hold it */ |
| 400 | skb_get(skb); |
| 401 | err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0); |
| 402 | if (err < 0) { |
| 403 | BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */ |
| 404 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); |
| 405 | audit_log_lost("auditd disappeared\n"); |
| 406 | audit_pid = 0; |
| 407 | /* we might get lucky and get this in the next auditd */ |
| 408 | audit_hold_skb(skb); |
| 409 | } else |
| 410 | /* drop the extra reference if sent ok */ |
| 411 | consume_skb(skb); |
| 412 | } |
| 413 | |
| 414 | static int kauditd_thread(void *dummy) |
| 415 | { |
| 416 | struct sk_buff *skb; |
| 417 | |
| 418 | set_freezable(); |
| 419 | while (!kthread_should_stop()) { |
| 420 | /* |
| 421 | * if auditd just started drain the queue of messages already |
| 422 | * sent to syslog/printk. remember loss here is ok. we already |
| 423 | * called audit_log_lost() if it didn't go out normally. so the |
| 424 | * race between the skb_dequeue and the next check for audit_pid |
| 425 | * doesn't matter. |
| 426 | * |
| 427 | * if you ever find kauditd to be too slow we can get a perf win |
| 428 | * by doing our own locking and keeping better track if there |
| 429 | * are messages in this queue. I don't see the need now, but |
| 430 | * in 5 years when I want to play with this again I'll see this |
| 431 | * note and still have no friggin idea what i'm thinking today. |
| 432 | */ |
| 433 | if (audit_default && audit_pid) { |
| 434 | skb = skb_dequeue(&audit_skb_hold_queue); |
| 435 | if (unlikely(skb)) { |
| 436 | while (skb && audit_pid) { |
| 437 | kauditd_send_skb(skb); |
| 438 | skb = skb_dequeue(&audit_skb_hold_queue); |
| 439 | } |
| 440 | } |
| 441 | } |
| 442 | |
| 443 | skb = skb_dequeue(&audit_skb_queue); |
| 444 | wake_up(&audit_backlog_wait); |
| 445 | if (skb) { |
| 446 | if (audit_pid) |
| 447 | kauditd_send_skb(skb); |
| 448 | else |
| 449 | audit_printk_skb(skb); |
| 450 | } else { |
| 451 | DECLARE_WAITQUEUE(wait, current); |
| 452 | set_current_state(TASK_INTERRUPTIBLE); |
| 453 | add_wait_queue(&kauditd_wait, &wait); |
| 454 | |
| 455 | if (!skb_queue_len(&audit_skb_queue)) { |
| 456 | try_to_freeze(); |
| 457 | schedule(); |
| 458 | } |
| 459 | |
| 460 | __set_current_state(TASK_RUNNING); |
| 461 | remove_wait_queue(&kauditd_wait, &wait); |
| 462 | } |
| 463 | } |
| 464 | return 0; |
| 465 | } |
| 466 | |
| 467 | static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid) |
| 468 | { |
| 469 | struct task_struct *tsk; |
| 470 | int err; |
| 471 | |
| 472 | rcu_read_lock(); |
| 473 | tsk = find_task_by_vpid(pid); |
| 474 | if (!tsk) { |
| 475 | rcu_read_unlock(); |
| 476 | return -ESRCH; |
| 477 | } |
| 478 | get_task_struct(tsk); |
| 479 | rcu_read_unlock(); |
| 480 | err = tty_audit_push_task(tsk, loginuid, sessionid); |
| 481 | put_task_struct(tsk); |
| 482 | return err; |
| 483 | } |
| 484 | |
| 485 | int audit_send_list(void *_dest) |
| 486 | { |
| 487 | struct audit_netlink_list *dest = _dest; |
| 488 | int pid = dest->pid; |
| 489 | struct sk_buff *skb; |
| 490 | |
| 491 | /* wait for parent to finish and send an ACK */ |
| 492 | mutex_lock(&audit_cmd_mutex); |
| 493 | mutex_unlock(&audit_cmd_mutex); |
| 494 | |
| 495 | while ((skb = __skb_dequeue(&dest->q)) != NULL) |
| 496 | netlink_unicast(audit_sock, skb, pid, 0); |
| 497 | |
| 498 | kfree(dest); |
| 499 | |
| 500 | return 0; |
| 501 | } |
| 502 | |
| 503 | struct sk_buff *audit_make_reply(int pid, int seq, int type, int done, |
| 504 | int multi, const void *payload, int size) |
| 505 | { |
| 506 | struct sk_buff *skb; |
| 507 | struct nlmsghdr *nlh; |
| 508 | void *data; |
| 509 | int flags = multi ? NLM_F_MULTI : 0; |
| 510 | int t = done ? NLMSG_DONE : type; |
| 511 | |
| 512 | skb = nlmsg_new(size, GFP_KERNEL); |
| 513 | if (!skb) |
| 514 | return NULL; |
| 515 | |
| 516 | nlh = NLMSG_NEW(skb, pid, seq, t, size, flags); |
| 517 | data = NLMSG_DATA(nlh); |
| 518 | memcpy(data, payload, size); |
| 519 | return skb; |
| 520 | |
| 521 | nlmsg_failure: /* Used by NLMSG_NEW */ |
| 522 | if (skb) |
| 523 | kfree_skb(skb); |
| 524 | return NULL; |
| 525 | } |
| 526 | |
| 527 | static int audit_send_reply_thread(void *arg) |
| 528 | { |
| 529 | struct audit_reply *reply = (struct audit_reply *)arg; |
| 530 | |
| 531 | mutex_lock(&audit_cmd_mutex); |
| 532 | mutex_unlock(&audit_cmd_mutex); |
| 533 | |
| 534 | /* Ignore failure. It'll only happen if the sender goes away, |
| 535 | because our timeout is set to infinite. */ |
| 536 | netlink_unicast(audit_sock, reply->skb, reply->pid, 0); |
| 537 | kfree(reply); |
| 538 | return 0; |
| 539 | } |
| 540 | /** |
| 541 | * audit_send_reply - send an audit reply message via netlink |
| 542 | * @pid: process id to send reply to |
| 543 | * @seq: sequence number |
| 544 | * @type: audit message type |
| 545 | * @done: done (last) flag |
| 546 | * @multi: multi-part message flag |
| 547 | * @payload: payload data |
| 548 | * @size: payload size |
| 549 | * |
| 550 | * Allocates an skb, builds the netlink message, and sends it to the pid. |
| 551 | * No failure notifications. |
| 552 | */ |
| 553 | static void audit_send_reply(int pid, int seq, int type, int done, int multi, |
| 554 | const void *payload, int size) |
| 555 | { |
| 556 | struct sk_buff *skb; |
| 557 | struct task_struct *tsk; |
| 558 | struct audit_reply *reply = kmalloc(sizeof(struct audit_reply), |
| 559 | GFP_KERNEL); |
| 560 | |
| 561 | if (!reply) |
| 562 | return; |
| 563 | |
| 564 | skb = audit_make_reply(pid, seq, type, done, multi, payload, size); |
| 565 | if (!skb) |
| 566 | goto out; |
| 567 | |
| 568 | reply->pid = pid; |
| 569 | reply->skb = skb; |
| 570 | |
| 571 | tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); |
| 572 | if (!IS_ERR(tsk)) |
| 573 | return; |
| 574 | kfree_skb(skb); |
| 575 | out: |
| 576 | kfree(reply); |
| 577 | } |
| 578 | |
| 579 | /* |
| 580 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit |
| 581 | * control messages. |
| 582 | */ |
| 583 | static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) |
| 584 | { |
| 585 | int err = 0; |
| 586 | |
| 587 | switch (msg_type) { |
| 588 | case AUDIT_GET: |
| 589 | case AUDIT_LIST: |
| 590 | case AUDIT_LIST_RULES: |
| 591 | case AUDIT_SET: |
| 592 | case AUDIT_ADD: |
| 593 | case AUDIT_ADD_RULE: |
| 594 | case AUDIT_DEL: |
| 595 | case AUDIT_DEL_RULE: |
| 596 | case AUDIT_SIGNAL_INFO: |
| 597 | case AUDIT_TTY_GET: |
| 598 | case AUDIT_TTY_SET: |
| 599 | case AUDIT_TRIM: |
| 600 | case AUDIT_MAKE_EQUIV: |
| 601 | if (security_netlink_recv(skb, CAP_AUDIT_CONTROL)) |
| 602 | err = -EPERM; |
| 603 | break; |
| 604 | case AUDIT_USER: |
| 605 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: |
| 606 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: |
| 607 | if (security_netlink_recv(skb, CAP_AUDIT_WRITE)) |
| 608 | err = -EPERM; |
| 609 | break; |
| 610 | default: /* bad msg */ |
| 611 | err = -EINVAL; |
| 612 | } |
| 613 | |
| 614 | return err; |
| 615 | } |
| 616 | |
| 617 | static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type, |
| 618 | u32 pid, u32 uid, uid_t auid, u32 ses, |
| 619 | u32 sid) |
| 620 | { |
| 621 | int rc = 0; |
| 622 | char *ctx = NULL; |
| 623 | u32 len; |
| 624 | |
| 625 | if (!audit_enabled) { |
| 626 | *ab = NULL; |
| 627 | return rc; |
| 628 | } |
| 629 | |
| 630 | *ab = audit_log_start(NULL, GFP_KERNEL, msg_type); |
| 631 | audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u", |
| 632 | pid, uid, auid, ses); |
| 633 | if (sid) { |
| 634 | rc = security_secid_to_secctx(sid, &ctx, &len); |
| 635 | if (rc) |
| 636 | audit_log_format(*ab, " ssid=%u", sid); |
| 637 | else { |
| 638 | audit_log_format(*ab, " subj=%s", ctx); |
| 639 | security_release_secctx(ctx, len); |
| 640 | } |
| 641 | } |
| 642 | |
| 643 | return rc; |
| 644 | } |
| 645 | |
| 646 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) |
| 647 | { |
| 648 | u32 uid, pid, seq, sid; |
| 649 | void *data; |
| 650 | struct audit_status *status_get, status_set; |
| 651 | int err; |
| 652 | struct audit_buffer *ab; |
| 653 | u16 msg_type = nlh->nlmsg_type; |
| 654 | uid_t loginuid; /* loginuid of sender */ |
| 655 | u32 sessionid; |
| 656 | struct audit_sig_info *sig_data; |
| 657 | char *ctx = NULL; |
| 658 | u32 len; |
| 659 | |
| 660 | err = audit_netlink_ok(skb, msg_type); |
| 661 | if (err) |
| 662 | return err; |
| 663 | |
| 664 | /* As soon as there's any sign of userspace auditd, |
| 665 | * start kauditd to talk to it */ |
| 666 | if (!kauditd_task) |
| 667 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); |
| 668 | if (IS_ERR(kauditd_task)) { |
| 669 | err = PTR_ERR(kauditd_task); |
| 670 | kauditd_task = NULL; |
| 671 | return err; |
| 672 | } |
| 673 | |
| 674 | pid = NETLINK_CREDS(skb)->pid; |
| 675 | uid = NETLINK_CREDS(skb)->uid; |
| 676 | loginuid = audit_get_loginuid(current); |
| 677 | sessionid = audit_get_sessionid(current); |
| 678 | security_task_getsecid(current, &sid); |
| 679 | seq = nlh->nlmsg_seq; |
| 680 | data = NLMSG_DATA(nlh); |
| 681 | |
| 682 | switch (msg_type) { |
| 683 | case AUDIT_GET: |
| 684 | status_set.enabled = audit_enabled; |
| 685 | status_set.failure = audit_failure; |
| 686 | status_set.pid = audit_pid; |
| 687 | status_set.rate_limit = audit_rate_limit; |
| 688 | status_set.backlog_limit = audit_backlog_limit; |
| 689 | status_set.lost = atomic_read(&audit_lost); |
| 690 | status_set.backlog = skb_queue_len(&audit_skb_queue); |
| 691 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0, |
| 692 | &status_set, sizeof(status_set)); |
| 693 | break; |
| 694 | case AUDIT_SET: |
| 695 | if (nlh->nlmsg_len < sizeof(struct audit_status)) |
| 696 | return -EINVAL; |
| 697 | status_get = (struct audit_status *)data; |
| 698 | if (status_get->mask & AUDIT_STATUS_ENABLED) { |
| 699 | err = audit_set_enabled(status_get->enabled, |
| 700 | loginuid, sessionid, sid); |
| 701 | if (err < 0) |
| 702 | return err; |
| 703 | } |
| 704 | if (status_get->mask & AUDIT_STATUS_FAILURE) { |
| 705 | err = audit_set_failure(status_get->failure, |
| 706 | loginuid, sessionid, sid); |
| 707 | if (err < 0) |
| 708 | return err; |
| 709 | } |
| 710 | if (status_get->mask & AUDIT_STATUS_PID) { |
| 711 | int new_pid = status_get->pid; |
| 712 | |
| 713 | if (audit_enabled != AUDIT_OFF) |
| 714 | audit_log_config_change("audit_pid", new_pid, |
| 715 | audit_pid, loginuid, |
| 716 | sessionid, sid, 1); |
| 717 | |
| 718 | audit_pid = new_pid; |
| 719 | audit_nlk_pid = NETLINK_CB(skb).pid; |
| 720 | } |
| 721 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) { |
| 722 | err = audit_set_rate_limit(status_get->rate_limit, |
| 723 | loginuid, sessionid, sid); |
| 724 | if (err < 0) |
| 725 | return err; |
| 726 | } |
| 727 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
| 728 | err = audit_set_backlog_limit(status_get->backlog_limit, |
| 729 | loginuid, sessionid, sid); |
| 730 | break; |
| 731 | case AUDIT_USER: |
| 732 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: |
| 733 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: |
| 734 | if (!audit_enabled && msg_type != AUDIT_USER_AVC) |
| 735 | return 0; |
| 736 | |
| 737 | err = audit_filter_user(&NETLINK_CB(skb)); |
| 738 | if (err == 1) { |
| 739 | err = 0; |
| 740 | if (msg_type == AUDIT_USER_TTY) { |
| 741 | err = audit_prepare_user_tty(pid, loginuid, |
| 742 | sessionid); |
| 743 | if (err) |
| 744 | break; |
| 745 | } |
| 746 | audit_log_common_recv_msg(&ab, msg_type, pid, uid, |
| 747 | loginuid, sessionid, sid); |
| 748 | |
| 749 | if (msg_type != AUDIT_USER_TTY) |
| 750 | audit_log_format(ab, " msg='%.1024s'", |
| 751 | (char *)data); |
| 752 | else { |
| 753 | int size; |
| 754 | |
| 755 | audit_log_format(ab, " msg="); |
| 756 | size = nlmsg_len(nlh); |
| 757 | if (size > 0 && |
| 758 | ((unsigned char *)data)[size - 1] == '\0') |
| 759 | size--; |
| 760 | audit_log_n_untrustedstring(ab, data, size); |
| 761 | } |
| 762 | audit_set_pid(ab, pid); |
| 763 | audit_log_end(ab); |
| 764 | } |
| 765 | break; |
| 766 | case AUDIT_ADD: |
| 767 | case AUDIT_DEL: |
| 768 | if (nlmsg_len(nlh) < sizeof(struct audit_rule)) |
| 769 | return -EINVAL; |
| 770 | if (audit_enabled == AUDIT_LOCKED) { |
| 771 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
| 772 | uid, loginuid, sessionid, sid); |
| 773 | |
| 774 | audit_log_format(ab, " audit_enabled=%d res=0", |
| 775 | audit_enabled); |
| 776 | audit_log_end(ab); |
| 777 | return -EPERM; |
| 778 | } |
| 779 | /* fallthrough */ |
| 780 | case AUDIT_LIST: |
| 781 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, |
| 782 | uid, seq, data, nlmsg_len(nlh), |
| 783 | loginuid, sessionid, sid); |
| 784 | break; |
| 785 | case AUDIT_ADD_RULE: |
| 786 | case AUDIT_DEL_RULE: |
| 787 | if (nlmsg_len(nlh) < sizeof(struct audit_rule_data)) |
| 788 | return -EINVAL; |
| 789 | if (audit_enabled == AUDIT_LOCKED) { |
| 790 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
| 791 | uid, loginuid, sessionid, sid); |
| 792 | |
| 793 | audit_log_format(ab, " audit_enabled=%d res=0", |
| 794 | audit_enabled); |
| 795 | audit_log_end(ab); |
| 796 | return -EPERM; |
| 797 | } |
| 798 | /* fallthrough */ |
| 799 | case AUDIT_LIST_RULES: |
| 800 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid, |
| 801 | uid, seq, data, nlmsg_len(nlh), |
| 802 | loginuid, sessionid, sid); |
| 803 | break; |
| 804 | case AUDIT_TRIM: |
| 805 | audit_trim_trees(); |
| 806 | |
| 807 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
| 808 | uid, loginuid, sessionid, sid); |
| 809 | |
| 810 | audit_log_format(ab, " op=trim res=1"); |
| 811 | audit_log_end(ab); |
| 812 | break; |
| 813 | case AUDIT_MAKE_EQUIV: { |
| 814 | void *bufp = data; |
| 815 | u32 sizes[2]; |
| 816 | size_t msglen = nlmsg_len(nlh); |
| 817 | char *old, *new; |
| 818 | |
| 819 | err = -EINVAL; |
| 820 | if (msglen < 2 * sizeof(u32)) |
| 821 | break; |
| 822 | memcpy(sizes, bufp, 2 * sizeof(u32)); |
| 823 | bufp += 2 * sizeof(u32); |
| 824 | msglen -= 2 * sizeof(u32); |
| 825 | old = audit_unpack_string(&bufp, &msglen, sizes[0]); |
| 826 | if (IS_ERR(old)) { |
| 827 | err = PTR_ERR(old); |
| 828 | break; |
| 829 | } |
| 830 | new = audit_unpack_string(&bufp, &msglen, sizes[1]); |
| 831 | if (IS_ERR(new)) { |
| 832 | err = PTR_ERR(new); |
| 833 | kfree(old); |
| 834 | break; |
| 835 | } |
| 836 | /* OK, here comes... */ |
| 837 | err = audit_tag_tree(old, new); |
| 838 | |
| 839 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid, |
| 840 | uid, loginuid, sessionid, sid); |
| 841 | |
| 842 | audit_log_format(ab, " op=make_equiv old="); |
| 843 | audit_log_untrustedstring(ab, old); |
| 844 | audit_log_format(ab, " new="); |
| 845 | audit_log_untrustedstring(ab, new); |
| 846 | audit_log_format(ab, " res=%d", !err); |
| 847 | audit_log_end(ab); |
| 848 | kfree(old); |
| 849 | kfree(new); |
| 850 | break; |
| 851 | } |
| 852 | case AUDIT_SIGNAL_INFO: |
| 853 | len = 0; |
| 854 | if (audit_sig_sid) { |
| 855 | err = security_secid_to_secctx(audit_sig_sid, &ctx, &len); |
| 856 | if (err) |
| 857 | return err; |
| 858 | } |
| 859 | sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL); |
| 860 | if (!sig_data) { |
| 861 | if (audit_sig_sid) |
| 862 | security_release_secctx(ctx, len); |
| 863 | return -ENOMEM; |
| 864 | } |
| 865 | sig_data->uid = audit_sig_uid; |
| 866 | sig_data->pid = audit_sig_pid; |
| 867 | if (audit_sig_sid) { |
| 868 | memcpy(sig_data->ctx, ctx, len); |
| 869 | security_release_secctx(ctx, len); |
| 870 | } |
| 871 | audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO, |
| 872 | 0, 0, sig_data, sizeof(*sig_data) + len); |
| 873 | kfree(sig_data); |
| 874 | break; |
| 875 | case AUDIT_TTY_GET: { |
| 876 | struct audit_tty_status s; |
| 877 | struct task_struct *tsk; |
| 878 | unsigned long flags; |
| 879 | |
| 880 | rcu_read_lock(); |
| 881 | tsk = find_task_by_vpid(pid); |
| 882 | if (tsk && lock_task_sighand(tsk, &flags)) { |
| 883 | s.enabled = tsk->signal->audit_tty != 0; |
| 884 | unlock_task_sighand(tsk, &flags); |
| 885 | } else |
| 886 | err = -ESRCH; |
| 887 | rcu_read_unlock(); |
| 888 | |
| 889 | if (!err) |
| 890 | audit_send_reply(NETLINK_CB(skb).pid, seq, |
| 891 | AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); |
| 892 | break; |
| 893 | } |
| 894 | case AUDIT_TTY_SET: { |
| 895 | struct audit_tty_status *s; |
| 896 | struct task_struct *tsk; |
| 897 | unsigned long flags; |
| 898 | |
| 899 | if (nlh->nlmsg_len < sizeof(struct audit_tty_status)) |
| 900 | return -EINVAL; |
| 901 | s = data; |
| 902 | if (s->enabled != 0 && s->enabled != 1) |
| 903 | return -EINVAL; |
| 904 | rcu_read_lock(); |
| 905 | tsk = find_task_by_vpid(pid); |
| 906 | if (tsk && lock_task_sighand(tsk, &flags)) { |
| 907 | tsk->signal->audit_tty = s->enabled != 0; |
| 908 | unlock_task_sighand(tsk, &flags); |
| 909 | } else |
| 910 | err = -ESRCH; |
| 911 | rcu_read_unlock(); |
| 912 | break; |
| 913 | } |
| 914 | default: |
| 915 | err = -EINVAL; |
| 916 | break; |
| 917 | } |
| 918 | |
| 919 | return err < 0 ? err : 0; |
| 920 | } |
| 921 | |
| 922 | /* |
| 923 | * Get message from skb. Each message is processed by audit_receive_msg. |
| 924 | * Malformed skbs with wrong length are discarded silently. |
| 925 | */ |
| 926 | static void audit_receive_skb(struct sk_buff *skb) |
| 927 | { |
| 928 | struct nlmsghdr *nlh; |
| 929 | /* |
| 930 | * len MUST be signed for NLMSG_NEXT to be able to dec it below 0 |
| 931 | * if the nlmsg_len was not aligned |
| 932 | */ |
| 933 | int len; |
| 934 | int err; |
| 935 | |
| 936 | nlh = nlmsg_hdr(skb); |
| 937 | len = skb->len; |
| 938 | |
| 939 | while (NLMSG_OK(nlh, len)) { |
| 940 | err = audit_receive_msg(skb, nlh); |
| 941 | /* if err or if this message says it wants a response */ |
| 942 | if (err || (nlh->nlmsg_flags & NLM_F_ACK)) |
| 943 | netlink_ack(skb, nlh, err); |
| 944 | |
| 945 | nlh = NLMSG_NEXT(nlh, len); |
| 946 | } |
| 947 | } |
| 948 | |
| 949 | /* Receive messages from netlink socket. */ |
| 950 | static void audit_receive(struct sk_buff *skb) |
| 951 | { |
| 952 | mutex_lock(&audit_cmd_mutex); |
| 953 | audit_receive_skb(skb); |
| 954 | mutex_unlock(&audit_cmd_mutex); |
| 955 | } |
| 956 | |
| 957 | /* Initialize audit support at boot time. */ |
| 958 | static int __init audit_init(void) |
| 959 | { |
| 960 | int i; |
| 961 | |
| 962 | if (audit_initialized == AUDIT_DISABLED) |
| 963 | return 0; |
| 964 | |
| 965 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", |
| 966 | audit_default ? "enabled" : "disabled"); |
| 967 | audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0, |
| 968 | audit_receive, NULL, THIS_MODULE); |
| 969 | if (!audit_sock) |
| 970 | audit_panic("cannot initialize netlink socket"); |
| 971 | else |
| 972 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; |
| 973 | |
| 974 | skb_queue_head_init(&audit_skb_queue); |
| 975 | skb_queue_head_init(&audit_skb_hold_queue); |
| 976 | audit_initialized = AUDIT_INITIALIZED; |
| 977 | audit_enabled = audit_default; |
| 978 | audit_ever_enabled |= !!audit_default; |
| 979 | |
| 980 | audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized"); |
| 981 | |
| 982 | for (i = 0; i < AUDIT_INODE_BUCKETS; i++) |
| 983 | INIT_LIST_HEAD(&audit_inode_hash[i]); |
| 984 | |
| 985 | return 0; |
| 986 | } |
| 987 | __initcall(audit_init); |
| 988 | |
| 989 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ |
| 990 | static int __init audit_enable(char *str) |
| 991 | { |
| 992 | audit_default = !!simple_strtol(str, NULL, 0); |
| 993 | if (!audit_default) |
| 994 | audit_initialized = AUDIT_DISABLED; |
| 995 | |
| 996 | printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled"); |
| 997 | |
| 998 | if (audit_initialized == AUDIT_INITIALIZED) { |
| 999 | audit_enabled = audit_default; |
| 1000 | audit_ever_enabled |= !!audit_default; |
| 1001 | } else if (audit_initialized == AUDIT_UNINITIALIZED) { |
| 1002 | printk(" (after initialization)"); |
| 1003 | } else { |
| 1004 | printk(" (until reboot)"); |
| 1005 | } |
| 1006 | printk("\n"); |
| 1007 | |
| 1008 | return 1; |
| 1009 | } |
| 1010 | |
| 1011 | __setup("audit=", audit_enable); |
| 1012 | |
| 1013 | static void audit_buffer_free(struct audit_buffer *ab) |
| 1014 | { |
| 1015 | unsigned long flags; |
| 1016 | |
| 1017 | if (!ab) |
| 1018 | return; |
| 1019 | |
| 1020 | if (ab->skb) |
| 1021 | kfree_skb(ab->skb); |
| 1022 | |
| 1023 | spin_lock_irqsave(&audit_freelist_lock, flags); |
| 1024 | if (audit_freelist_count > AUDIT_MAXFREE) |
| 1025 | kfree(ab); |
| 1026 | else { |
| 1027 | audit_freelist_count++; |
| 1028 | list_add(&ab->list, &audit_freelist); |
| 1029 | } |
| 1030 | spin_unlock_irqrestore(&audit_freelist_lock, flags); |
| 1031 | } |
| 1032 | |
| 1033 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
| 1034 | gfp_t gfp_mask, int type) |
| 1035 | { |
| 1036 | unsigned long flags; |
| 1037 | struct audit_buffer *ab = NULL; |
| 1038 | struct nlmsghdr *nlh; |
| 1039 | |
| 1040 | spin_lock_irqsave(&audit_freelist_lock, flags); |
| 1041 | if (!list_empty(&audit_freelist)) { |
| 1042 | ab = list_entry(audit_freelist.next, |
| 1043 | struct audit_buffer, list); |
| 1044 | list_del(&ab->list); |
| 1045 | --audit_freelist_count; |
| 1046 | } |
| 1047 | spin_unlock_irqrestore(&audit_freelist_lock, flags); |
| 1048 | |
| 1049 | if (!ab) { |
| 1050 | ab = kmalloc(sizeof(*ab), gfp_mask); |
| 1051 | if (!ab) |
| 1052 | goto err; |
| 1053 | } |
| 1054 | |
| 1055 | ab->ctx = ctx; |
| 1056 | ab->gfp_mask = gfp_mask; |
| 1057 | |
| 1058 | ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); |
| 1059 | if (!ab->skb) |
| 1060 | goto nlmsg_failure; |
| 1061 | |
| 1062 | nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0); |
| 1063 | |
| 1064 | return ab; |
| 1065 | |
| 1066 | nlmsg_failure: /* Used by NLMSG_NEW */ |
| 1067 | kfree_skb(ab->skb); |
| 1068 | ab->skb = NULL; |
| 1069 | err: |
| 1070 | audit_buffer_free(ab); |
| 1071 | return NULL; |
| 1072 | } |
| 1073 | |
| 1074 | /** |
| 1075 | * audit_serial - compute a serial number for the audit record |
| 1076 | * |
| 1077 | * Compute a serial number for the audit record. Audit records are |
| 1078 | * written to user-space as soon as they are generated, so a complete |
| 1079 | * audit record may be written in several pieces. The timestamp of the |
| 1080 | * record and this serial number are used by the user-space tools to |
| 1081 | * determine which pieces belong to the same audit record. The |
| 1082 | * (timestamp,serial) tuple is unique for each syscall and is live from |
| 1083 | * syscall entry to syscall exit. |
| 1084 | * |
| 1085 | * NOTE: Another possibility is to store the formatted records off the |
| 1086 | * audit context (for those records that have a context), and emit them |
| 1087 | * all at syscall exit. However, this could delay the reporting of |
| 1088 | * significant errors until syscall exit (or never, if the system |
| 1089 | * halts). |
| 1090 | */ |
| 1091 | unsigned int audit_serial(void) |
| 1092 | { |
| 1093 | static DEFINE_SPINLOCK(serial_lock); |
| 1094 | static unsigned int serial = 0; |
| 1095 | |
| 1096 | unsigned long flags; |
| 1097 | unsigned int ret; |
| 1098 | |
| 1099 | spin_lock_irqsave(&serial_lock, flags); |
| 1100 | do { |
| 1101 | ret = ++serial; |
| 1102 | } while (unlikely(!ret)); |
| 1103 | spin_unlock_irqrestore(&serial_lock, flags); |
| 1104 | |
| 1105 | return ret; |
| 1106 | } |
| 1107 | |
| 1108 | static inline void audit_get_stamp(struct audit_context *ctx, |
| 1109 | struct timespec *t, unsigned int *serial) |
| 1110 | { |
| 1111 | if (!ctx || !auditsc_get_stamp(ctx, t, serial)) { |
| 1112 | *t = CURRENT_TIME; |
| 1113 | *serial = audit_serial(); |
| 1114 | } |
| 1115 | } |
| 1116 | |
| 1117 | /* Obtain an audit buffer. This routine does locking to obtain the |
| 1118 | * audit buffer, but then no locking is required for calls to |
| 1119 | * audit_log_*format. If the tsk is a task that is currently in a |
| 1120 | * syscall, then the syscall is marked as auditable and an audit record |
| 1121 | * will be written at syscall exit. If there is no associated task, tsk |
| 1122 | * should be NULL. */ |
| 1123 | |
| 1124 | /** |
| 1125 | * audit_log_start - obtain an audit buffer |
| 1126 | * @ctx: audit_context (may be NULL) |
| 1127 | * @gfp_mask: type of allocation |
| 1128 | * @type: audit message type |
| 1129 | * |
| 1130 | * Returns audit_buffer pointer on success or NULL on error. |
| 1131 | * |
| 1132 | * Obtain an audit buffer. This routine does locking to obtain the |
| 1133 | * audit buffer, but then no locking is required for calls to |
| 1134 | * audit_log_*format. If the task (ctx) is a task that is currently in a |
| 1135 | * syscall, then the syscall is marked as auditable and an audit record |
| 1136 | * will be written at syscall exit. If there is no associated task, then |
| 1137 | * task context (ctx) should be NULL. |
| 1138 | */ |
| 1139 | struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, |
| 1140 | int type) |
| 1141 | { |
| 1142 | struct audit_buffer *ab = NULL; |
| 1143 | struct timespec t; |
| 1144 | unsigned int uninitialized_var(serial); |
| 1145 | int reserve; |
| 1146 | unsigned long timeout_start = jiffies; |
| 1147 | |
| 1148 | if (audit_initialized != AUDIT_INITIALIZED) |
| 1149 | return NULL; |
| 1150 | |
| 1151 | if (unlikely(audit_filter_type(type))) |
| 1152 | return NULL; |
| 1153 | |
| 1154 | if (gfp_mask & __GFP_WAIT) |
| 1155 | reserve = 0; |
| 1156 | else |
| 1157 | reserve = 5; /* Allow atomic callers to go up to five |
| 1158 | entries over the normal backlog limit */ |
| 1159 | |
| 1160 | while (audit_backlog_limit |
| 1161 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { |
| 1162 | if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time |
| 1163 | && time_before(jiffies, timeout_start + audit_backlog_wait_time)) { |
| 1164 | |
| 1165 | /* Wait for auditd to drain the queue a little */ |
| 1166 | DECLARE_WAITQUEUE(wait, current); |
| 1167 | set_current_state(TASK_INTERRUPTIBLE); |
| 1168 | add_wait_queue(&audit_backlog_wait, &wait); |
| 1169 | |
| 1170 | if (audit_backlog_limit && |
| 1171 | skb_queue_len(&audit_skb_queue) > audit_backlog_limit) |
| 1172 | schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies); |
| 1173 | |
| 1174 | __set_current_state(TASK_RUNNING); |
| 1175 | remove_wait_queue(&audit_backlog_wait, &wait); |
| 1176 | continue; |
| 1177 | } |
| 1178 | if (audit_rate_check() && printk_ratelimit()) |
| 1179 | printk(KERN_WARNING |
| 1180 | "audit: audit_backlog=%d > " |
| 1181 | "audit_backlog_limit=%d\n", |
| 1182 | skb_queue_len(&audit_skb_queue), |
| 1183 | audit_backlog_limit); |
| 1184 | audit_log_lost("backlog limit exceeded"); |
| 1185 | audit_backlog_wait_time = audit_backlog_wait_overflow; |
| 1186 | wake_up(&audit_backlog_wait); |
| 1187 | return NULL; |
| 1188 | } |
| 1189 | |
| 1190 | ab = audit_buffer_alloc(ctx, gfp_mask, type); |
| 1191 | if (!ab) { |
| 1192 | audit_log_lost("out of memory in audit_log_start"); |
| 1193 | return NULL; |
| 1194 | } |
| 1195 | |
| 1196 | audit_get_stamp(ab->ctx, &t, &serial); |
| 1197 | |
| 1198 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
| 1199 | t.tv_sec, t.tv_nsec/1000000, serial); |
| 1200 | return ab; |
| 1201 | } |
| 1202 | |
| 1203 | /** |
| 1204 | * audit_expand - expand skb in the audit buffer |
| 1205 | * @ab: audit_buffer |
| 1206 | * @extra: space to add at tail of the skb |
| 1207 | * |
| 1208 | * Returns 0 (no space) on failed expansion, or available space if |
| 1209 | * successful. |
| 1210 | */ |
| 1211 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
| 1212 | { |
| 1213 | struct sk_buff *skb = ab->skb; |
| 1214 | int oldtail = skb_tailroom(skb); |
| 1215 | int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask); |
| 1216 | int newtail = skb_tailroom(skb); |
| 1217 | |
| 1218 | if (ret < 0) { |
| 1219 | audit_log_lost("out of memory in audit_expand"); |
| 1220 | return 0; |
| 1221 | } |
| 1222 | |
| 1223 | skb->truesize += newtail - oldtail; |
| 1224 | return newtail; |
| 1225 | } |
| 1226 | |
| 1227 | /* |
| 1228 | * Format an audit message into the audit buffer. If there isn't enough |
| 1229 | * room in the audit buffer, more room will be allocated and vsnprint |
| 1230 | * will be called a second time. Currently, we assume that a printk |
| 1231 | * can't format message larger than 1024 bytes, so we don't either. |
| 1232 | */ |
| 1233 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, |
| 1234 | va_list args) |
| 1235 | { |
| 1236 | int len, avail; |
| 1237 | struct sk_buff *skb; |
| 1238 | va_list args2; |
| 1239 | |
| 1240 | if (!ab) |
| 1241 | return; |
| 1242 | |
| 1243 | BUG_ON(!ab->skb); |
| 1244 | skb = ab->skb; |
| 1245 | avail = skb_tailroom(skb); |
| 1246 | if (avail == 0) { |
| 1247 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
| 1248 | if (!avail) |
| 1249 | goto out; |
| 1250 | } |
| 1251 | va_copy(args2, args); |
| 1252 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args); |
| 1253 | if (len >= avail) { |
| 1254 | /* The printk buffer is 1024 bytes long, so if we get |
| 1255 | * here and AUDIT_BUFSIZ is at least 1024, then we can |
| 1256 | * log everything that printk could have logged. */ |
| 1257 | avail = audit_expand(ab, |
| 1258 | max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); |
| 1259 | if (!avail) |
| 1260 | goto out; |
| 1261 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); |
| 1262 | } |
| 1263 | va_end(args2); |
| 1264 | if (len > 0) |
| 1265 | skb_put(skb, len); |
| 1266 | out: |
| 1267 | return; |
| 1268 | } |
| 1269 | |
| 1270 | /** |
| 1271 | * audit_log_format - format a message into the audit buffer. |
| 1272 | * @ab: audit_buffer |
| 1273 | * @fmt: format string |
| 1274 | * @...: optional parameters matching @fmt string |
| 1275 | * |
| 1276 | * All the work is done in audit_log_vformat. |
| 1277 | */ |
| 1278 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) |
| 1279 | { |
| 1280 | va_list args; |
| 1281 | |
| 1282 | if (!ab) |
| 1283 | return; |
| 1284 | va_start(args, fmt); |
| 1285 | audit_log_vformat(ab, fmt, args); |
| 1286 | va_end(args); |
| 1287 | } |
| 1288 | |
| 1289 | /** |
| 1290 | * audit_log_hex - convert a buffer to hex and append it to the audit skb |
| 1291 | * @ab: the audit_buffer |
| 1292 | * @buf: buffer to convert to hex |
| 1293 | * @len: length of @buf to be converted |
| 1294 | * |
| 1295 | * No return value; failure to expand is silently ignored. |
| 1296 | * |
| 1297 | * This function will take the passed buf and convert it into a string of |
| 1298 | * ascii hex digits. The new string is placed onto the skb. |
| 1299 | */ |
| 1300 | void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, |
| 1301 | size_t len) |
| 1302 | { |
| 1303 | int i, avail, new_len; |
| 1304 | unsigned char *ptr; |
| 1305 | struct sk_buff *skb; |
| 1306 | static const unsigned char *hex = "0123456789ABCDEF"; |
| 1307 | |
| 1308 | if (!ab) |
| 1309 | return; |
| 1310 | |
| 1311 | BUG_ON(!ab->skb); |
| 1312 | skb = ab->skb; |
| 1313 | avail = skb_tailroom(skb); |
| 1314 | new_len = len<<1; |
| 1315 | if (new_len >= avail) { |
| 1316 | /* Round the buffer request up to the next multiple */ |
| 1317 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); |
| 1318 | avail = audit_expand(ab, new_len); |
| 1319 | if (!avail) |
| 1320 | return; |
| 1321 | } |
| 1322 | |
| 1323 | ptr = skb_tail_pointer(skb); |
| 1324 | for (i=0; i<len; i++) { |
| 1325 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ |
| 1326 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ |
| 1327 | } |
| 1328 | *ptr = 0; |
| 1329 | skb_put(skb, len << 1); /* new string is twice the old string */ |
| 1330 | } |
| 1331 | |
| 1332 | /* |
| 1333 | * Format a string of no more than slen characters into the audit buffer, |
| 1334 | * enclosed in quote marks. |
| 1335 | */ |
| 1336 | void audit_log_n_string(struct audit_buffer *ab, const char *string, |
| 1337 | size_t slen) |
| 1338 | { |
| 1339 | int avail, new_len; |
| 1340 | unsigned char *ptr; |
| 1341 | struct sk_buff *skb; |
| 1342 | |
| 1343 | if (!ab) |
| 1344 | return; |
| 1345 | |
| 1346 | BUG_ON(!ab->skb); |
| 1347 | skb = ab->skb; |
| 1348 | avail = skb_tailroom(skb); |
| 1349 | new_len = slen + 3; /* enclosing quotes + null terminator */ |
| 1350 | if (new_len > avail) { |
| 1351 | avail = audit_expand(ab, new_len); |
| 1352 | if (!avail) |
| 1353 | return; |
| 1354 | } |
| 1355 | ptr = skb_tail_pointer(skb); |
| 1356 | *ptr++ = '"'; |
| 1357 | memcpy(ptr, string, slen); |
| 1358 | ptr += slen; |
| 1359 | *ptr++ = '"'; |
| 1360 | *ptr = 0; |
| 1361 | skb_put(skb, slen + 2); /* don't include null terminator */ |
| 1362 | } |
| 1363 | |
| 1364 | /** |
| 1365 | * audit_string_contains_control - does a string need to be logged in hex |
| 1366 | * @string: string to be checked |
| 1367 | * @len: max length of the string to check |
| 1368 | */ |
| 1369 | int audit_string_contains_control(const char *string, size_t len) |
| 1370 | { |
| 1371 | const unsigned char *p; |
| 1372 | for (p = string; p < (const unsigned char *)string + len; p++) { |
| 1373 | if (*p == '"' || *p < 0x21 || *p > 0x7e) |
| 1374 | return 1; |
| 1375 | } |
| 1376 | return 0; |
| 1377 | } |
| 1378 | |
| 1379 | /** |
| 1380 | * audit_log_n_untrustedstring - log a string that may contain random characters |
| 1381 | * @ab: audit_buffer |
| 1382 | * @len: length of string (not including trailing null) |
| 1383 | * @string: string to be logged |
| 1384 | * |
| 1385 | * This code will escape a string that is passed to it if the string |
| 1386 | * contains a control character, unprintable character, double quote mark, |
| 1387 | * or a space. Unescaped strings will start and end with a double quote mark. |
| 1388 | * Strings that are escaped are printed in hex (2 digits per char). |
| 1389 | * |
| 1390 | * The caller specifies the number of characters in the string to log, which may |
| 1391 | * or may not be the entire string. |
| 1392 | */ |
| 1393 | void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string, |
| 1394 | size_t len) |
| 1395 | { |
| 1396 | if (audit_string_contains_control(string, len)) |
| 1397 | audit_log_n_hex(ab, string, len); |
| 1398 | else |
| 1399 | audit_log_n_string(ab, string, len); |
| 1400 | } |
| 1401 | |
| 1402 | /** |
| 1403 | * audit_log_untrustedstring - log a string that may contain random characters |
| 1404 | * @ab: audit_buffer |
| 1405 | * @string: string to be logged |
| 1406 | * |
| 1407 | * Same as audit_log_n_untrustedstring(), except that strlen is used to |
| 1408 | * determine string length. |
| 1409 | */ |
| 1410 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) |
| 1411 | { |
| 1412 | audit_log_n_untrustedstring(ab, string, strlen(string)); |
| 1413 | } |
| 1414 | |
| 1415 | /* This is a helper-function to print the escaped d_path */ |
| 1416 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, |
| 1417 | struct path *path) |
| 1418 | { |
| 1419 | char *p, *pathname; |
| 1420 | |
| 1421 | if (prefix) |
| 1422 | audit_log_format(ab, " %s", prefix); |
| 1423 | |
| 1424 | /* We will allow 11 spaces for ' (deleted)' to be appended */ |
| 1425 | pathname = kmalloc(PATH_MAX+11, ab->gfp_mask); |
| 1426 | if (!pathname) { |
| 1427 | audit_log_string(ab, "<no_memory>"); |
| 1428 | return; |
| 1429 | } |
| 1430 | p = d_path(path, pathname, PATH_MAX+11); |
| 1431 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ |
| 1432 | /* FIXME: can we save some information here? */ |
| 1433 | audit_log_string(ab, "<too_long>"); |
| 1434 | } else |
| 1435 | audit_log_untrustedstring(ab, p); |
| 1436 | kfree(pathname); |
| 1437 | } |
| 1438 | |
| 1439 | void audit_log_key(struct audit_buffer *ab, char *key) |
| 1440 | { |
| 1441 | audit_log_format(ab, " key="); |
| 1442 | if (key) |
| 1443 | audit_log_untrustedstring(ab, key); |
| 1444 | else |
| 1445 | audit_log_format(ab, "(null)"); |
| 1446 | } |
| 1447 | |
| 1448 | /** |
| 1449 | * audit_log_end - end one audit record |
| 1450 | * @ab: the audit_buffer |
| 1451 | * |
| 1452 | * The netlink_* functions cannot be called inside an irq context, so |
| 1453 | * the audit buffer is placed on a queue and a tasklet is scheduled to |
| 1454 | * remove them from the queue outside the irq context. May be called in |
| 1455 | * any context. |
| 1456 | */ |
| 1457 | void audit_log_end(struct audit_buffer *ab) |
| 1458 | { |
| 1459 | if (!ab) |
| 1460 | return; |
| 1461 | if (!audit_rate_check()) { |
| 1462 | audit_log_lost("rate limit exceeded"); |
| 1463 | } else { |
| 1464 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); |
| 1465 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); |
| 1466 | |
| 1467 | if (audit_pid) { |
| 1468 | skb_queue_tail(&audit_skb_queue, ab->skb); |
| 1469 | wake_up_interruptible(&kauditd_wait); |
| 1470 | } else { |
| 1471 | audit_printk_skb(ab->skb); |
| 1472 | } |
| 1473 | ab->skb = NULL; |
| 1474 | } |
| 1475 | audit_buffer_free(ab); |
| 1476 | } |
| 1477 | |
| 1478 | /** |
| 1479 | * audit_log - Log an audit record |
| 1480 | * @ctx: audit context |
| 1481 | * @gfp_mask: type of allocation |
| 1482 | * @type: audit message type |
| 1483 | * @fmt: format string to use |
| 1484 | * @...: variable parameters matching the format string |
| 1485 | * |
| 1486 | * This is a convenience function that calls audit_log_start, |
| 1487 | * audit_log_vformat, and audit_log_end. It may be called |
| 1488 | * in any context. |
| 1489 | */ |
| 1490 | void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, |
| 1491 | const char *fmt, ...) |
| 1492 | { |
| 1493 | struct audit_buffer *ab; |
| 1494 | va_list args; |
| 1495 | |
| 1496 | ab = audit_log_start(ctx, gfp_mask, type); |
| 1497 | if (ab) { |
| 1498 | va_start(args, fmt); |
| 1499 | audit_log_vformat(ab, fmt, args); |
| 1500 | va_end(args); |
| 1501 | audit_log_end(ab); |
| 1502 | } |
| 1503 | } |
| 1504 | |
| 1505 | EXPORT_SYMBOL(audit_log_start); |
| 1506 | EXPORT_SYMBOL(audit_log_end); |
| 1507 | EXPORT_SYMBOL(audit_log_format); |
| 1508 | EXPORT_SYMBOL(audit_log); |