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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 <linux/atomic.h> |
47 | #include <linux/mm.h> |
48 | #include <linux/export.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 | #ifdef CONFIG_SECURITY |
59 | #include <linux/security.h> |
60 | #endif |
61 | #include <linux/netlink.h> |
62 | #include <linux/freezer.h> |
63 | #include <linux/tty.h> |
64 | #include <linux/pid_namespace.h> |
65 | |
66 | #include "audit.h" |
67 | |
68 | /* No auditing will take place until audit_initialized == AUDIT_INITIALIZED. |
69 | * (Initialization happens after skb_init is called.) */ |
70 | #define AUDIT_DISABLED -1 |
71 | #define AUDIT_UNINITIALIZED 0 |
72 | #define AUDIT_INITIALIZED 1 |
73 | static int audit_initialized; |
74 | |
75 | #define AUDIT_OFF 0 |
76 | #define AUDIT_ON 1 |
77 | #define AUDIT_LOCKED 2 |
78 | int audit_enabled; |
79 | int audit_ever_enabled; |
80 | |
81 | EXPORT_SYMBOL_GPL(audit_enabled); |
82 | |
83 | /* Default state when kernel boots without any parameters. */ |
84 | static int audit_default; |
85 | |
86 | /* If auditing cannot proceed, audit_failure selects what happens. */ |
87 | static int audit_failure = AUDIT_FAIL_PRINTK; |
88 | |
89 | /* |
90 | * If audit records are to be written to the netlink socket, audit_pid |
91 | * contains the pid of the auditd process and audit_nlk_portid contains |
92 | * the portid to use to send netlink messages to that process. |
93 | */ |
94 | int audit_pid; |
95 | static int audit_nlk_portid; |
96 | |
97 | /* If audit_rate_limit is non-zero, limit the rate of sending audit records |
98 | * to that number per second. This prevents DoS attacks, but results in |
99 | * audit records being dropped. */ |
100 | static int audit_rate_limit; |
101 | |
102 | /* Number of outstanding audit_buffers allowed. */ |
103 | static int audit_backlog_limit = 64; |
104 | static int audit_backlog_wait_time = 60 * HZ; |
105 | static int audit_backlog_wait_overflow = 0; |
106 | |
107 | /* The identity of the user shutting down the audit system. */ |
108 | kuid_t audit_sig_uid = INVALID_UID; |
109 | pid_t audit_sig_pid = -1; |
110 | u32 audit_sig_sid = 0; |
111 | |
112 | /* Records can be lost in several ways: |
113 | 0) [suppressed in audit_alloc] |
114 | 1) out of memory in audit_log_start [kmalloc of struct audit_buffer] |
115 | 2) out of memory in audit_log_move [alloc_skb] |
116 | 3) suppressed due to audit_rate_limit |
117 | 4) suppressed due to audit_backlog_limit |
118 | */ |
119 | static atomic_t audit_lost = ATOMIC_INIT(0); |
120 | |
121 | /* The netlink socket. */ |
122 | static struct sock *audit_sock; |
123 | |
124 | /* Hash for inode-based rules */ |
125 | struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS]; |
126 | |
127 | /* The audit_freelist is a list of pre-allocated audit buffers (if more |
128 | * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of |
129 | * being placed on the freelist). */ |
130 | static DEFINE_SPINLOCK(audit_freelist_lock); |
131 | static int audit_freelist_count; |
132 | static LIST_HEAD(audit_freelist); |
133 | |
134 | static struct sk_buff_head audit_skb_queue; |
135 | /* queue of skbs to send to auditd when/if it comes back */ |
136 | static struct sk_buff_head audit_skb_hold_queue; |
137 | static struct task_struct *kauditd_task; |
138 | static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); |
139 | static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); |
140 | |
141 | /* Serialize requests from userspace. */ |
142 | DEFINE_MUTEX(audit_cmd_mutex); |
143 | |
144 | /* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting |
145 | * audit records. Since printk uses a 1024 byte buffer, this buffer |
146 | * should be at least that large. */ |
147 | #define AUDIT_BUFSIZ 1024 |
148 | |
149 | /* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the |
150 | * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */ |
151 | #define AUDIT_MAXFREE (2*NR_CPUS) |
152 | |
153 | /* The audit_buffer is used when formatting an audit record. The caller |
154 | * locks briefly to get the record off the freelist or to allocate the |
155 | * buffer, and locks briefly to send the buffer to the netlink layer or |
156 | * to place it on a transmit queue. Multiple audit_buffers can be in |
157 | * use simultaneously. */ |
158 | struct audit_buffer { |
159 | struct list_head list; |
160 | struct sk_buff *skb; /* formatted skb ready to send */ |
161 | struct audit_context *ctx; /* NULL or associated context */ |
162 | gfp_t gfp_mask; |
163 | }; |
164 | |
165 | struct audit_reply { |
166 | int pid; |
167 | struct sk_buff *skb; |
168 | }; |
169 | |
170 | static void audit_set_pid(struct audit_buffer *ab, pid_t pid) |
171 | { |
172 | if (ab) { |
173 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); |
174 | nlh->nlmsg_pid = pid; |
175 | } |
176 | } |
177 | |
178 | void audit_panic(const char *message) |
179 | { |
180 | switch (audit_failure) |
181 | { |
182 | case AUDIT_FAIL_SILENT: |
183 | break; |
184 | case AUDIT_FAIL_PRINTK: |
185 | if (printk_ratelimit()) |
186 | printk(KERN_ERR "audit: %s\n", message); |
187 | break; |
188 | case AUDIT_FAIL_PANIC: |
189 | /* test audit_pid since printk is always losey, why bother? */ |
190 | if (audit_pid) |
191 | panic("audit: %s\n", message); |
192 | break; |
193 | } |
194 | } |
195 | |
196 | static inline int audit_rate_check(void) |
197 | { |
198 | static unsigned long last_check = 0; |
199 | static int messages = 0; |
200 | static DEFINE_SPINLOCK(lock); |
201 | unsigned long flags; |
202 | unsigned long now; |
203 | unsigned long elapsed; |
204 | int retval = 0; |
205 | |
206 | if (!audit_rate_limit) return 1; |
207 | |
208 | spin_lock_irqsave(&lock, flags); |
209 | if (++messages < audit_rate_limit) { |
210 | retval = 1; |
211 | } else { |
212 | now = jiffies; |
213 | elapsed = now - last_check; |
214 | if (elapsed > HZ) { |
215 | last_check = now; |
216 | messages = 0; |
217 | retval = 1; |
218 | } |
219 | } |
220 | spin_unlock_irqrestore(&lock, flags); |
221 | |
222 | return retval; |
223 | } |
224 | |
225 | /** |
226 | * audit_log_lost - conditionally log lost audit message event |
227 | * @message: the message stating reason for lost audit message |
228 | * |
229 | * Emit at least 1 message per second, even if audit_rate_check is |
230 | * throttling. |
231 | * Always increment the lost messages counter. |
232 | */ |
233 | void audit_log_lost(const char *message) |
234 | { |
235 | static unsigned long last_msg = 0; |
236 | static DEFINE_SPINLOCK(lock); |
237 | unsigned long flags; |
238 | unsigned long now; |
239 | int print; |
240 | |
241 | atomic_inc(&audit_lost); |
242 | |
243 | print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit); |
244 | |
245 | if (!print) { |
246 | spin_lock_irqsave(&lock, flags); |
247 | now = jiffies; |
248 | if (now - last_msg > HZ) { |
249 | print = 1; |
250 | last_msg = now; |
251 | } |
252 | spin_unlock_irqrestore(&lock, flags); |
253 | } |
254 | |
255 | if (print) { |
256 | if (printk_ratelimit()) |
257 | printk(KERN_WARNING |
258 | "audit: audit_lost=%d audit_rate_limit=%d " |
259 | "audit_backlog_limit=%d\n", |
260 | atomic_read(&audit_lost), |
261 | audit_rate_limit, |
262 | audit_backlog_limit); |
263 | audit_panic(message); |
264 | } |
265 | } |
266 | |
267 | static int audit_log_config_change(char *function_name, int new, int old, |
268 | kuid_t loginuid, u32 sessionid, u32 sid, |
269 | int allow_changes) |
270 | { |
271 | struct audit_buffer *ab; |
272 | int rc = 0; |
273 | |
274 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); |
275 | if (unlikely(!ab)) |
276 | return rc; |
277 | audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new, |
278 | old, from_kuid(&init_user_ns, loginuid), sessionid); |
279 | if (sid) { |
280 | char *ctx = NULL; |
281 | u32 len; |
282 | |
283 | rc = security_secid_to_secctx(sid, &ctx, &len); |
284 | if (rc) { |
285 | audit_log_format(ab, " sid=%u", sid); |
286 | allow_changes = 0; /* Something weird, deny request */ |
287 | } else { |
288 | audit_log_format(ab, " subj=%s", ctx); |
289 | security_release_secctx(ctx, len); |
290 | } |
291 | } |
292 | audit_log_format(ab, " res=%d", allow_changes); |
293 | audit_log_end(ab); |
294 | return rc; |
295 | } |
296 | |
297 | static int audit_do_config_change(char *function_name, int *to_change, |
298 | int new, kuid_t loginuid, u32 sessionid, |
299 | u32 sid) |
300 | { |
301 | int allow_changes, rc = 0, old = *to_change; |
302 | |
303 | /* check if we are locked */ |
304 | if (audit_enabled == AUDIT_LOCKED) |
305 | allow_changes = 0; |
306 | else |
307 | allow_changes = 1; |
308 | |
309 | if (audit_enabled != AUDIT_OFF) { |
310 | rc = audit_log_config_change(function_name, new, old, loginuid, |
311 | sessionid, sid, allow_changes); |
312 | if (rc) |
313 | allow_changes = 0; |
314 | } |
315 | |
316 | /* If we are allowed, make the change */ |
317 | if (allow_changes == 1) |
318 | *to_change = new; |
319 | /* Not allowed, update reason */ |
320 | else if (rc == 0) |
321 | rc = -EPERM; |
322 | return rc; |
323 | } |
324 | |
325 | static int audit_set_rate_limit(int limit, kuid_t loginuid, u32 sessionid, |
326 | u32 sid) |
327 | { |
328 | return audit_do_config_change("audit_rate_limit", &audit_rate_limit, |
329 | limit, loginuid, sessionid, sid); |
330 | } |
331 | |
332 | static int audit_set_backlog_limit(int limit, kuid_t loginuid, u32 sessionid, |
333 | u32 sid) |
334 | { |
335 | return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, |
336 | limit, loginuid, sessionid, sid); |
337 | } |
338 | |
339 | static int audit_set_enabled(int state, kuid_t loginuid, u32 sessionid, u32 sid) |
340 | { |
341 | int rc; |
342 | if (state < AUDIT_OFF || state > AUDIT_LOCKED) |
343 | return -EINVAL; |
344 | |
345 | rc = audit_do_config_change("audit_enabled", &audit_enabled, state, |
346 | loginuid, sessionid, sid); |
347 | |
348 | if (!rc) |
349 | audit_ever_enabled |= !!state; |
350 | |
351 | return rc; |
352 | } |
353 | |
354 | static int audit_set_failure(int state, kuid_t loginuid, u32 sessionid, u32 sid) |
355 | { |
356 | if (state != AUDIT_FAIL_SILENT |
357 | && state != AUDIT_FAIL_PRINTK |
358 | && state != AUDIT_FAIL_PANIC) |
359 | return -EINVAL; |
360 | |
361 | return audit_do_config_change("audit_failure", &audit_failure, state, |
362 | loginuid, sessionid, sid); |
363 | } |
364 | |
365 | /* |
366 | * Queue skbs to be sent to auditd when/if it comes back. These skbs should |
367 | * already have been sent via prink/syslog and so if these messages are dropped |
368 | * it is not a huge concern since we already passed the audit_log_lost() |
369 | * notification and stuff. This is just nice to get audit messages during |
370 | * boot before auditd is running or messages generated while auditd is stopped. |
371 | * This only holds messages is audit_default is set, aka booting with audit=1 |
372 | * or building your kernel that way. |
373 | */ |
374 | static void audit_hold_skb(struct sk_buff *skb) |
375 | { |
376 | if (audit_default && |
377 | skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit) |
378 | skb_queue_tail(&audit_skb_hold_queue, skb); |
379 | else |
380 | kfree_skb(skb); |
381 | } |
382 | |
383 | /* |
384 | * For one reason or another this nlh isn't getting delivered to the userspace |
385 | * audit daemon, just send it to printk. |
386 | */ |
387 | static void audit_printk_skb(struct sk_buff *skb) |
388 | { |
389 | struct nlmsghdr *nlh = nlmsg_hdr(skb); |
390 | char *data = nlmsg_data(nlh); |
391 | |
392 | if (nlh->nlmsg_type != AUDIT_EOE) { |
393 | if (printk_ratelimit()) |
394 | printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data); |
395 | else |
396 | audit_log_lost("printk limit exceeded\n"); |
397 | } |
398 | |
399 | audit_hold_skb(skb); |
400 | } |
401 | |
402 | static void kauditd_send_skb(struct sk_buff *skb) |
403 | { |
404 | int err; |
405 | /* take a reference in case we can't send it and we want to hold it */ |
406 | skb_get(skb); |
407 | err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0); |
408 | if (err < 0) { |
409 | BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */ |
410 | printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid); |
411 | audit_log_lost("auditd disappeared\n"); |
412 | audit_pid = 0; |
413 | /* we might get lucky and get this in the next auditd */ |
414 | audit_hold_skb(skb); |
415 | } else |
416 | /* drop the extra reference if sent ok */ |
417 | consume_skb(skb); |
418 | } |
419 | |
420 | static int kauditd_thread(void *dummy) |
421 | { |
422 | struct sk_buff *skb; |
423 | |
424 | set_freezable(); |
425 | while (!kthread_should_stop()) { |
426 | /* |
427 | * if auditd just started drain the queue of messages already |
428 | * sent to syslog/printk. remember loss here is ok. we already |
429 | * called audit_log_lost() if it didn't go out normally. so the |
430 | * race between the skb_dequeue and the next check for audit_pid |
431 | * doesn't matter. |
432 | * |
433 | * if you ever find kauditd to be too slow we can get a perf win |
434 | * by doing our own locking and keeping better track if there |
435 | * are messages in this queue. I don't see the need now, but |
436 | * in 5 years when I want to play with this again I'll see this |
437 | * note and still have no friggin idea what i'm thinking today. |
438 | */ |
439 | if (audit_default && audit_pid) { |
440 | skb = skb_dequeue(&audit_skb_hold_queue); |
441 | if (unlikely(skb)) { |
442 | while (skb && audit_pid) { |
443 | kauditd_send_skb(skb); |
444 | skb = skb_dequeue(&audit_skb_hold_queue); |
445 | } |
446 | } |
447 | } |
448 | |
449 | skb = skb_dequeue(&audit_skb_queue); |
450 | wake_up(&audit_backlog_wait); |
451 | if (skb) { |
452 | if (audit_pid) |
453 | kauditd_send_skb(skb); |
454 | else |
455 | audit_printk_skb(skb); |
456 | } else { |
457 | DECLARE_WAITQUEUE(wait, current); |
458 | set_current_state(TASK_INTERRUPTIBLE); |
459 | add_wait_queue(&kauditd_wait, &wait); |
460 | |
461 | if (!skb_queue_len(&audit_skb_queue)) { |
462 | try_to_freeze(); |
463 | schedule(); |
464 | } |
465 | |
466 | __set_current_state(TASK_RUNNING); |
467 | remove_wait_queue(&kauditd_wait, &wait); |
468 | } |
469 | } |
470 | return 0; |
471 | } |
472 | |
473 | int audit_send_list(void *_dest) |
474 | { |
475 | struct audit_netlink_list *dest = _dest; |
476 | int pid = dest->pid; |
477 | struct sk_buff *skb; |
478 | |
479 | /* wait for parent to finish and send an ACK */ |
480 | mutex_lock(&audit_cmd_mutex); |
481 | mutex_unlock(&audit_cmd_mutex); |
482 | |
483 | while ((skb = __skb_dequeue(&dest->q)) != NULL) |
484 | netlink_unicast(audit_sock, skb, pid, 0); |
485 | |
486 | kfree(dest); |
487 | |
488 | return 0; |
489 | } |
490 | |
491 | struct sk_buff *audit_make_reply(int pid, int seq, int type, int done, |
492 | int multi, const void *payload, int size) |
493 | { |
494 | struct sk_buff *skb; |
495 | struct nlmsghdr *nlh; |
496 | void *data; |
497 | int flags = multi ? NLM_F_MULTI : 0; |
498 | int t = done ? NLMSG_DONE : type; |
499 | |
500 | skb = nlmsg_new(size, GFP_KERNEL); |
501 | if (!skb) |
502 | return NULL; |
503 | |
504 | nlh = nlmsg_put(skb, pid, seq, t, size, flags); |
505 | if (!nlh) |
506 | goto out_kfree_skb; |
507 | data = nlmsg_data(nlh); |
508 | memcpy(data, payload, size); |
509 | return skb; |
510 | |
511 | out_kfree_skb: |
512 | kfree_skb(skb); |
513 | return NULL; |
514 | } |
515 | |
516 | static int audit_send_reply_thread(void *arg) |
517 | { |
518 | struct audit_reply *reply = (struct audit_reply *)arg; |
519 | |
520 | mutex_lock(&audit_cmd_mutex); |
521 | mutex_unlock(&audit_cmd_mutex); |
522 | |
523 | /* Ignore failure. It'll only happen if the sender goes away, |
524 | because our timeout is set to infinite. */ |
525 | netlink_unicast(audit_sock, reply->skb, reply->pid, 0); |
526 | kfree(reply); |
527 | return 0; |
528 | } |
529 | /** |
530 | * audit_send_reply - send an audit reply message via netlink |
531 | * @pid: process id to send reply to |
532 | * @seq: sequence number |
533 | * @type: audit message type |
534 | * @done: done (last) flag |
535 | * @multi: multi-part message flag |
536 | * @payload: payload data |
537 | * @size: payload size |
538 | * |
539 | * Allocates an skb, builds the netlink message, and sends it to the pid. |
540 | * No failure notifications. |
541 | */ |
542 | static void audit_send_reply(int pid, int seq, int type, int done, int multi, |
543 | const void *payload, int size) |
544 | { |
545 | struct sk_buff *skb; |
546 | struct task_struct *tsk; |
547 | struct audit_reply *reply = kmalloc(sizeof(struct audit_reply), |
548 | GFP_KERNEL); |
549 | |
550 | if (!reply) |
551 | return; |
552 | |
553 | skb = audit_make_reply(pid, seq, type, done, multi, payload, size); |
554 | if (!skb) |
555 | goto out; |
556 | |
557 | reply->pid = pid; |
558 | reply->skb = skb; |
559 | |
560 | tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply"); |
561 | if (!IS_ERR(tsk)) |
562 | return; |
563 | kfree_skb(skb); |
564 | out: |
565 | kfree(reply); |
566 | } |
567 | |
568 | /* |
569 | * Check for appropriate CAP_AUDIT_ capabilities on incoming audit |
570 | * control messages. |
571 | */ |
572 | static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) |
573 | { |
574 | int err = 0; |
575 | |
576 | /* Only support the initial namespaces for now. */ |
577 | if ((current_user_ns() != &init_user_ns) || |
578 | (task_active_pid_ns(current) != &init_pid_ns)) |
579 | return -EPERM; |
580 | |
581 | switch (msg_type) { |
582 | case AUDIT_GET: |
583 | case AUDIT_LIST: |
584 | case AUDIT_LIST_RULES: |
585 | case AUDIT_SET: |
586 | case AUDIT_ADD: |
587 | case AUDIT_ADD_RULE: |
588 | case AUDIT_DEL: |
589 | case AUDIT_DEL_RULE: |
590 | case AUDIT_SIGNAL_INFO: |
591 | case AUDIT_TTY_GET: |
592 | case AUDIT_TTY_SET: |
593 | case AUDIT_TRIM: |
594 | case AUDIT_MAKE_EQUIV: |
595 | if (!capable(CAP_AUDIT_CONTROL)) |
596 | err = -EPERM; |
597 | break; |
598 | case AUDIT_USER: |
599 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: |
600 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: |
601 | if (!capable(CAP_AUDIT_WRITE)) |
602 | err = -EPERM; |
603 | break; |
604 | default: /* bad msg */ |
605 | err = -EINVAL; |
606 | } |
607 | |
608 | return err; |
609 | } |
610 | |
611 | static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type, |
612 | kuid_t auid, u32 ses, u32 sid) |
613 | { |
614 | int rc = 0; |
615 | char *ctx = NULL; |
616 | u32 len; |
617 | |
618 | if (!audit_enabled) { |
619 | *ab = NULL; |
620 | return rc; |
621 | } |
622 | |
623 | *ab = audit_log_start(NULL, GFP_KERNEL, msg_type); |
624 | if (unlikely(!*ab)) |
625 | return rc; |
626 | audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u", |
627 | task_tgid_vnr(current), |
628 | from_kuid(&init_user_ns, current_uid()), |
629 | from_kuid(&init_user_ns, auid), ses); |
630 | if (sid) { |
631 | rc = security_secid_to_secctx(sid, &ctx, &len); |
632 | if (rc) |
633 | audit_log_format(*ab, " ssid=%u", sid); |
634 | else { |
635 | audit_log_format(*ab, " subj=%s", ctx); |
636 | security_release_secctx(ctx, len); |
637 | } |
638 | } |
639 | |
640 | return rc; |
641 | } |
642 | |
643 | static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) |
644 | { |
645 | u32 seq, sid; |
646 | void *data; |
647 | struct audit_status *status_get, status_set; |
648 | int err; |
649 | struct audit_buffer *ab; |
650 | u16 msg_type = nlh->nlmsg_type; |
651 | kuid_t loginuid; /* loginuid of sender */ |
652 | u32 sessionid; |
653 | struct audit_sig_info *sig_data; |
654 | char *ctx = NULL; |
655 | u32 len; |
656 | |
657 | err = audit_netlink_ok(skb, msg_type); |
658 | if (err) |
659 | return err; |
660 | |
661 | /* As soon as there's any sign of userspace auditd, |
662 | * start kauditd to talk to it */ |
663 | if (!kauditd_task) |
664 | kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd"); |
665 | if (IS_ERR(kauditd_task)) { |
666 | err = PTR_ERR(kauditd_task); |
667 | kauditd_task = NULL; |
668 | return err; |
669 | } |
670 | |
671 | loginuid = audit_get_loginuid(current); |
672 | sessionid = audit_get_sessionid(current); |
673 | security_task_getsecid(current, &sid); |
674 | seq = nlh->nlmsg_seq; |
675 | data = nlmsg_data(nlh); |
676 | |
677 | switch (msg_type) { |
678 | case AUDIT_GET: |
679 | status_set.enabled = audit_enabled; |
680 | status_set.failure = audit_failure; |
681 | status_set.pid = audit_pid; |
682 | status_set.rate_limit = audit_rate_limit; |
683 | status_set.backlog_limit = audit_backlog_limit; |
684 | status_set.lost = atomic_read(&audit_lost); |
685 | status_set.backlog = skb_queue_len(&audit_skb_queue); |
686 | audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0, |
687 | &status_set, sizeof(status_set)); |
688 | break; |
689 | case AUDIT_SET: |
690 | if (nlh->nlmsg_len < sizeof(struct audit_status)) |
691 | return -EINVAL; |
692 | status_get = (struct audit_status *)data; |
693 | if (status_get->mask & AUDIT_STATUS_ENABLED) { |
694 | err = audit_set_enabled(status_get->enabled, |
695 | loginuid, sessionid, sid); |
696 | if (err < 0) |
697 | return err; |
698 | } |
699 | if (status_get->mask & AUDIT_STATUS_FAILURE) { |
700 | err = audit_set_failure(status_get->failure, |
701 | loginuid, sessionid, sid); |
702 | if (err < 0) |
703 | return err; |
704 | } |
705 | if (status_get->mask & AUDIT_STATUS_PID) { |
706 | int new_pid = status_get->pid; |
707 | |
708 | if (audit_enabled != AUDIT_OFF) |
709 | audit_log_config_change("audit_pid", new_pid, |
710 | audit_pid, loginuid, |
711 | sessionid, sid, 1); |
712 | |
713 | audit_pid = new_pid; |
714 | audit_nlk_portid = NETLINK_CB(skb).portid; |
715 | } |
716 | if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) { |
717 | err = audit_set_rate_limit(status_get->rate_limit, |
718 | loginuid, sessionid, sid); |
719 | if (err < 0) |
720 | return err; |
721 | } |
722 | if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) |
723 | err = audit_set_backlog_limit(status_get->backlog_limit, |
724 | loginuid, sessionid, sid); |
725 | break; |
726 | case AUDIT_USER: |
727 | case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: |
728 | case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: |
729 | if (!audit_enabled && msg_type != AUDIT_USER_AVC) |
730 | return 0; |
731 | |
732 | err = audit_filter_user(); |
733 | if (err == 1) { |
734 | err = 0; |
735 | if (msg_type == AUDIT_USER_TTY) { |
736 | err = tty_audit_push_task(current, loginuid, |
737 | sessionid); |
738 | if (err) |
739 | break; |
740 | } |
741 | audit_log_common_recv_msg(&ab, msg_type, |
742 | loginuid, sessionid, sid); |
743 | |
744 | if (msg_type != AUDIT_USER_TTY) |
745 | audit_log_format(ab, " msg='%.1024s'", |
746 | (char *)data); |
747 | else { |
748 | int size; |
749 | |
750 | audit_log_format(ab, " msg="); |
751 | size = nlmsg_len(nlh); |
752 | if (size > 0 && |
753 | ((unsigned char *)data)[size - 1] == '\0') |
754 | size--; |
755 | audit_log_n_untrustedstring(ab, data, size); |
756 | } |
757 | audit_set_pid(ab, NETLINK_CB(skb).portid); |
758 | audit_log_end(ab); |
759 | } |
760 | break; |
761 | case AUDIT_ADD: |
762 | case AUDIT_DEL: |
763 | if (nlmsg_len(nlh) < sizeof(struct audit_rule)) |
764 | return -EINVAL; |
765 | if (audit_enabled == AUDIT_LOCKED) { |
766 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, |
767 | loginuid, sessionid, sid); |
768 | |
769 | audit_log_format(ab, " audit_enabled=%d res=0", |
770 | audit_enabled); |
771 | audit_log_end(ab); |
772 | return -EPERM; |
773 | } |
774 | /* fallthrough */ |
775 | case AUDIT_LIST: |
776 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid, |
777 | seq, data, nlmsg_len(nlh), |
778 | loginuid, sessionid, sid); |
779 | break; |
780 | case AUDIT_ADD_RULE: |
781 | case AUDIT_DEL_RULE: |
782 | if (nlmsg_len(nlh) < sizeof(struct audit_rule_data)) |
783 | return -EINVAL; |
784 | if (audit_enabled == AUDIT_LOCKED) { |
785 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, |
786 | loginuid, sessionid, sid); |
787 | |
788 | audit_log_format(ab, " audit_enabled=%d res=0", |
789 | audit_enabled); |
790 | audit_log_end(ab); |
791 | return -EPERM; |
792 | } |
793 | /* fallthrough */ |
794 | case AUDIT_LIST_RULES: |
795 | err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid, |
796 | seq, data, nlmsg_len(nlh), |
797 | loginuid, sessionid, sid); |
798 | break; |
799 | case AUDIT_TRIM: |
800 | audit_trim_trees(); |
801 | |
802 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, |
803 | loginuid, sessionid, sid); |
804 | |
805 | audit_log_format(ab, " op=trim res=1"); |
806 | audit_log_end(ab); |
807 | break; |
808 | case AUDIT_MAKE_EQUIV: { |
809 | void *bufp = data; |
810 | u32 sizes[2]; |
811 | size_t msglen = nlmsg_len(nlh); |
812 | char *old, *new; |
813 | |
814 | err = -EINVAL; |
815 | if (msglen < 2 * sizeof(u32)) |
816 | break; |
817 | memcpy(sizes, bufp, 2 * sizeof(u32)); |
818 | bufp += 2 * sizeof(u32); |
819 | msglen -= 2 * sizeof(u32); |
820 | old = audit_unpack_string(&bufp, &msglen, sizes[0]); |
821 | if (IS_ERR(old)) { |
822 | err = PTR_ERR(old); |
823 | break; |
824 | } |
825 | new = audit_unpack_string(&bufp, &msglen, sizes[1]); |
826 | if (IS_ERR(new)) { |
827 | err = PTR_ERR(new); |
828 | kfree(old); |
829 | break; |
830 | } |
831 | /* OK, here comes... */ |
832 | err = audit_tag_tree(old, new); |
833 | |
834 | audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, |
835 | loginuid, sessionid, sid); |
836 | |
837 | audit_log_format(ab, " op=make_equiv old="); |
838 | audit_log_untrustedstring(ab, old); |
839 | audit_log_format(ab, " new="); |
840 | audit_log_untrustedstring(ab, new); |
841 | audit_log_format(ab, " res=%d", !err); |
842 | audit_log_end(ab); |
843 | kfree(old); |
844 | kfree(new); |
845 | break; |
846 | } |
847 | case AUDIT_SIGNAL_INFO: |
848 | len = 0; |
849 | if (audit_sig_sid) { |
850 | err = security_secid_to_secctx(audit_sig_sid, &ctx, &len); |
851 | if (err) |
852 | return err; |
853 | } |
854 | sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL); |
855 | if (!sig_data) { |
856 | if (audit_sig_sid) |
857 | security_release_secctx(ctx, len); |
858 | return -ENOMEM; |
859 | } |
860 | sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid); |
861 | sig_data->pid = audit_sig_pid; |
862 | if (audit_sig_sid) { |
863 | memcpy(sig_data->ctx, ctx, len); |
864 | security_release_secctx(ctx, len); |
865 | } |
866 | audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO, |
867 | 0, 0, sig_data, sizeof(*sig_data) + len); |
868 | kfree(sig_data); |
869 | break; |
870 | case AUDIT_TTY_GET: { |
871 | struct audit_tty_status s; |
872 | struct task_struct *tsk = current; |
873 | |
874 | spin_lock_irq(&tsk->sighand->siglock); |
875 | s.enabled = tsk->signal->audit_tty != 0; |
876 | spin_unlock_irq(&tsk->sighand->siglock); |
877 | |
878 | audit_send_reply(NETLINK_CB(skb).portid, seq, |
879 | AUDIT_TTY_GET, 0, 0, &s, sizeof(s)); |
880 | break; |
881 | } |
882 | case AUDIT_TTY_SET: { |
883 | struct audit_tty_status *s; |
884 | struct task_struct *tsk = current; |
885 | |
886 | if (nlh->nlmsg_len < sizeof(struct audit_tty_status)) |
887 | return -EINVAL; |
888 | s = data; |
889 | if (s->enabled != 0 && s->enabled != 1) |
890 | return -EINVAL; |
891 | |
892 | spin_lock_irq(&tsk->sighand->siglock); |
893 | tsk->signal->audit_tty = s->enabled != 0; |
894 | spin_unlock_irq(&tsk->sighand->siglock); |
895 | break; |
896 | } |
897 | default: |
898 | err = -EINVAL; |
899 | break; |
900 | } |
901 | |
902 | return err < 0 ? err : 0; |
903 | } |
904 | |
905 | /* |
906 | * Get message from skb. Each message is processed by audit_receive_msg. |
907 | * Malformed skbs with wrong length are discarded silently. |
908 | */ |
909 | static void audit_receive_skb(struct sk_buff *skb) |
910 | { |
911 | struct nlmsghdr *nlh; |
912 | /* |
913 | * len MUST be signed for NLMSG_NEXT to be able to dec it below 0 |
914 | * if the nlmsg_len was not aligned |
915 | */ |
916 | int len; |
917 | int err; |
918 | |
919 | nlh = nlmsg_hdr(skb); |
920 | len = skb->len; |
921 | |
922 | while (NLMSG_OK(nlh, len)) { |
923 | err = audit_receive_msg(skb, nlh); |
924 | /* if err or if this message says it wants a response */ |
925 | if (err || (nlh->nlmsg_flags & NLM_F_ACK)) |
926 | netlink_ack(skb, nlh, err); |
927 | |
928 | nlh = NLMSG_NEXT(nlh, len); |
929 | } |
930 | } |
931 | |
932 | /* Receive messages from netlink socket. */ |
933 | static void audit_receive(struct sk_buff *skb) |
934 | { |
935 | mutex_lock(&audit_cmd_mutex); |
936 | audit_receive_skb(skb); |
937 | mutex_unlock(&audit_cmd_mutex); |
938 | } |
939 | |
940 | /* Initialize audit support at boot time. */ |
941 | static int __init audit_init(void) |
942 | { |
943 | int i; |
944 | struct netlink_kernel_cfg cfg = { |
945 | .input = audit_receive, |
946 | }; |
947 | |
948 | if (audit_initialized == AUDIT_DISABLED) |
949 | return 0; |
950 | |
951 | printk(KERN_INFO "audit: initializing netlink socket (%s)\n", |
952 | audit_default ? "enabled" : "disabled"); |
953 | audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg); |
954 | if (!audit_sock) |
955 | audit_panic("cannot initialize netlink socket"); |
956 | else |
957 | audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; |
958 | |
959 | skb_queue_head_init(&audit_skb_queue); |
960 | skb_queue_head_init(&audit_skb_hold_queue); |
961 | audit_initialized = AUDIT_INITIALIZED; |
962 | audit_enabled = audit_default; |
963 | audit_ever_enabled |= !!audit_default; |
964 | |
965 | audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized"); |
966 | |
967 | for (i = 0; i < AUDIT_INODE_BUCKETS; i++) |
968 | INIT_LIST_HEAD(&audit_inode_hash[i]); |
969 | |
970 | return 0; |
971 | } |
972 | __initcall(audit_init); |
973 | |
974 | /* Process kernel command-line parameter at boot time. audit=0 or audit=1. */ |
975 | static int __init audit_enable(char *str) |
976 | { |
977 | audit_default = !!simple_strtol(str, NULL, 0); |
978 | if (!audit_default) |
979 | audit_initialized = AUDIT_DISABLED; |
980 | |
981 | printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled"); |
982 | |
983 | if (audit_initialized == AUDIT_INITIALIZED) { |
984 | audit_enabled = audit_default; |
985 | audit_ever_enabled |= !!audit_default; |
986 | } else if (audit_initialized == AUDIT_UNINITIALIZED) { |
987 | printk(" (after initialization)"); |
988 | } else { |
989 | printk(" (until reboot)"); |
990 | } |
991 | printk("\n"); |
992 | |
993 | return 1; |
994 | } |
995 | |
996 | __setup("audit=", audit_enable); |
997 | |
998 | static void audit_buffer_free(struct audit_buffer *ab) |
999 | { |
1000 | unsigned long flags; |
1001 | |
1002 | if (!ab) |
1003 | return; |
1004 | |
1005 | if (ab->skb) |
1006 | kfree_skb(ab->skb); |
1007 | |
1008 | spin_lock_irqsave(&audit_freelist_lock, flags); |
1009 | if (audit_freelist_count > AUDIT_MAXFREE) |
1010 | kfree(ab); |
1011 | else { |
1012 | audit_freelist_count++; |
1013 | list_add(&ab->list, &audit_freelist); |
1014 | } |
1015 | spin_unlock_irqrestore(&audit_freelist_lock, flags); |
1016 | } |
1017 | |
1018 | static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx, |
1019 | gfp_t gfp_mask, int type) |
1020 | { |
1021 | unsigned long flags; |
1022 | struct audit_buffer *ab = NULL; |
1023 | struct nlmsghdr *nlh; |
1024 | |
1025 | spin_lock_irqsave(&audit_freelist_lock, flags); |
1026 | if (!list_empty(&audit_freelist)) { |
1027 | ab = list_entry(audit_freelist.next, |
1028 | struct audit_buffer, list); |
1029 | list_del(&ab->list); |
1030 | --audit_freelist_count; |
1031 | } |
1032 | spin_unlock_irqrestore(&audit_freelist_lock, flags); |
1033 | |
1034 | if (!ab) { |
1035 | ab = kmalloc(sizeof(*ab), gfp_mask); |
1036 | if (!ab) |
1037 | goto err; |
1038 | } |
1039 | |
1040 | ab->ctx = ctx; |
1041 | ab->gfp_mask = gfp_mask; |
1042 | |
1043 | ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask); |
1044 | if (!ab->skb) |
1045 | goto err; |
1046 | |
1047 | nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0); |
1048 | if (!nlh) |
1049 | goto out_kfree_skb; |
1050 | |
1051 | return ab; |
1052 | |
1053 | out_kfree_skb: |
1054 | kfree_skb(ab->skb); |
1055 | ab->skb = NULL; |
1056 | err: |
1057 | audit_buffer_free(ab); |
1058 | return NULL; |
1059 | } |
1060 | |
1061 | /** |
1062 | * audit_serial - compute a serial number for the audit record |
1063 | * |
1064 | * Compute a serial number for the audit record. Audit records are |
1065 | * written to user-space as soon as they are generated, so a complete |
1066 | * audit record may be written in several pieces. The timestamp of the |
1067 | * record and this serial number are used by the user-space tools to |
1068 | * determine which pieces belong to the same audit record. The |
1069 | * (timestamp,serial) tuple is unique for each syscall and is live from |
1070 | * syscall entry to syscall exit. |
1071 | * |
1072 | * NOTE: Another possibility is to store the formatted records off the |
1073 | * audit context (for those records that have a context), and emit them |
1074 | * all at syscall exit. However, this could delay the reporting of |
1075 | * significant errors until syscall exit (or never, if the system |
1076 | * halts). |
1077 | */ |
1078 | unsigned int audit_serial(void) |
1079 | { |
1080 | static DEFINE_SPINLOCK(serial_lock); |
1081 | static unsigned int serial = 0; |
1082 | |
1083 | unsigned long flags; |
1084 | unsigned int ret; |
1085 | |
1086 | spin_lock_irqsave(&serial_lock, flags); |
1087 | do { |
1088 | ret = ++serial; |
1089 | } while (unlikely(!ret)); |
1090 | spin_unlock_irqrestore(&serial_lock, flags); |
1091 | |
1092 | return ret; |
1093 | } |
1094 | |
1095 | static inline void audit_get_stamp(struct audit_context *ctx, |
1096 | struct timespec *t, unsigned int *serial) |
1097 | { |
1098 | if (!ctx || !auditsc_get_stamp(ctx, t, serial)) { |
1099 | *t = CURRENT_TIME; |
1100 | *serial = audit_serial(); |
1101 | } |
1102 | } |
1103 | |
1104 | /* |
1105 | * Wait for auditd to drain the queue a little |
1106 | */ |
1107 | static void wait_for_auditd(unsigned long sleep_time) |
1108 | { |
1109 | DECLARE_WAITQUEUE(wait, current); |
1110 | set_current_state(TASK_INTERRUPTIBLE); |
1111 | add_wait_queue(&audit_backlog_wait, &wait); |
1112 | |
1113 | if (audit_backlog_limit && |
1114 | skb_queue_len(&audit_skb_queue) > audit_backlog_limit) |
1115 | schedule_timeout(sleep_time); |
1116 | |
1117 | __set_current_state(TASK_RUNNING); |
1118 | remove_wait_queue(&audit_backlog_wait, &wait); |
1119 | } |
1120 | |
1121 | /* Obtain an audit buffer. This routine does locking to obtain the |
1122 | * audit buffer, but then no locking is required for calls to |
1123 | * audit_log_*format. If the tsk is a task that is currently in a |
1124 | * syscall, then the syscall is marked as auditable and an audit record |
1125 | * will be written at syscall exit. If there is no associated task, tsk |
1126 | * should be NULL. */ |
1127 | |
1128 | /** |
1129 | * audit_log_start - obtain an audit buffer |
1130 | * @ctx: audit_context (may be NULL) |
1131 | * @gfp_mask: type of allocation |
1132 | * @type: audit message type |
1133 | * |
1134 | * Returns audit_buffer pointer on success or NULL on error. |
1135 | * |
1136 | * Obtain an audit buffer. This routine does locking to obtain the |
1137 | * audit buffer, but then no locking is required for calls to |
1138 | * audit_log_*format. If the task (ctx) is a task that is currently in a |
1139 | * syscall, then the syscall is marked as auditable and an audit record |
1140 | * will be written at syscall exit. If there is no associated task, then |
1141 | * task context (ctx) should be NULL. |
1142 | */ |
1143 | struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, |
1144 | int type) |
1145 | { |
1146 | struct audit_buffer *ab = NULL; |
1147 | struct timespec t; |
1148 | unsigned int uninitialized_var(serial); |
1149 | int reserve; |
1150 | unsigned long timeout_start = jiffies; |
1151 | |
1152 | if (audit_initialized != AUDIT_INITIALIZED) |
1153 | return NULL; |
1154 | |
1155 | if (unlikely(audit_filter_type(type))) |
1156 | return NULL; |
1157 | |
1158 | if (gfp_mask & __GFP_WAIT) |
1159 | reserve = 0; |
1160 | else |
1161 | reserve = 5; /* Allow atomic callers to go up to five |
1162 | entries over the normal backlog limit */ |
1163 | |
1164 | while (audit_backlog_limit |
1165 | && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) { |
1166 | if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) { |
1167 | unsigned long sleep_time; |
1168 | |
1169 | sleep_time = timeout_start + audit_backlog_wait_time - |
1170 | jiffies; |
1171 | if ((long)sleep_time > 0) |
1172 | wait_for_auditd(sleep_time); |
1173 | continue; |
1174 | } |
1175 | if (audit_rate_check() && printk_ratelimit()) |
1176 | printk(KERN_WARNING |
1177 | "audit: audit_backlog=%d > " |
1178 | "audit_backlog_limit=%d\n", |
1179 | skb_queue_len(&audit_skb_queue), |
1180 | audit_backlog_limit); |
1181 | audit_log_lost("backlog limit exceeded"); |
1182 | audit_backlog_wait_time = audit_backlog_wait_overflow; |
1183 | wake_up(&audit_backlog_wait); |
1184 | return NULL; |
1185 | } |
1186 | |
1187 | ab = audit_buffer_alloc(ctx, gfp_mask, type); |
1188 | if (!ab) { |
1189 | audit_log_lost("out of memory in audit_log_start"); |
1190 | return NULL; |
1191 | } |
1192 | |
1193 | audit_get_stamp(ab->ctx, &t, &serial); |
1194 | |
1195 | audit_log_format(ab, "audit(%lu.%03lu:%u): ", |
1196 | t.tv_sec, t.tv_nsec/1000000, serial); |
1197 | return ab; |
1198 | } |
1199 | |
1200 | /** |
1201 | * audit_expand - expand skb in the audit buffer |
1202 | * @ab: audit_buffer |
1203 | * @extra: space to add at tail of the skb |
1204 | * |
1205 | * Returns 0 (no space) on failed expansion, or available space if |
1206 | * successful. |
1207 | */ |
1208 | static inline int audit_expand(struct audit_buffer *ab, int extra) |
1209 | { |
1210 | struct sk_buff *skb = ab->skb; |
1211 | int oldtail = skb_tailroom(skb); |
1212 | int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask); |
1213 | int newtail = skb_tailroom(skb); |
1214 | |
1215 | if (ret < 0) { |
1216 | audit_log_lost("out of memory in audit_expand"); |
1217 | return 0; |
1218 | } |
1219 | |
1220 | skb->truesize += newtail - oldtail; |
1221 | return newtail; |
1222 | } |
1223 | |
1224 | /* |
1225 | * Format an audit message into the audit buffer. If there isn't enough |
1226 | * room in the audit buffer, more room will be allocated and vsnprint |
1227 | * will be called a second time. Currently, we assume that a printk |
1228 | * can't format message larger than 1024 bytes, so we don't either. |
1229 | */ |
1230 | static void audit_log_vformat(struct audit_buffer *ab, const char *fmt, |
1231 | va_list args) |
1232 | { |
1233 | int len, avail; |
1234 | struct sk_buff *skb; |
1235 | va_list args2; |
1236 | |
1237 | if (!ab) |
1238 | return; |
1239 | |
1240 | BUG_ON(!ab->skb); |
1241 | skb = ab->skb; |
1242 | avail = skb_tailroom(skb); |
1243 | if (avail == 0) { |
1244 | avail = audit_expand(ab, AUDIT_BUFSIZ); |
1245 | if (!avail) |
1246 | goto out; |
1247 | } |
1248 | va_copy(args2, args); |
1249 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args); |
1250 | if (len >= avail) { |
1251 | /* The printk buffer is 1024 bytes long, so if we get |
1252 | * here and AUDIT_BUFSIZ is at least 1024, then we can |
1253 | * log everything that printk could have logged. */ |
1254 | avail = audit_expand(ab, |
1255 | max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail)); |
1256 | if (!avail) |
1257 | goto out_va_end; |
1258 | len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2); |
1259 | } |
1260 | if (len > 0) |
1261 | skb_put(skb, len); |
1262 | out_va_end: |
1263 | va_end(args2); |
1264 | out: |
1265 | return; |
1266 | } |
1267 | |
1268 | /** |
1269 | * audit_log_format - format a message into the audit buffer. |
1270 | * @ab: audit_buffer |
1271 | * @fmt: format string |
1272 | * @...: optional parameters matching @fmt string |
1273 | * |
1274 | * All the work is done in audit_log_vformat. |
1275 | */ |
1276 | void audit_log_format(struct audit_buffer *ab, const char *fmt, ...) |
1277 | { |
1278 | va_list args; |
1279 | |
1280 | if (!ab) |
1281 | return; |
1282 | va_start(args, fmt); |
1283 | audit_log_vformat(ab, fmt, args); |
1284 | va_end(args); |
1285 | } |
1286 | |
1287 | /** |
1288 | * audit_log_hex - convert a buffer to hex and append it to the audit skb |
1289 | * @ab: the audit_buffer |
1290 | * @buf: buffer to convert to hex |
1291 | * @len: length of @buf to be converted |
1292 | * |
1293 | * No return value; failure to expand is silently ignored. |
1294 | * |
1295 | * This function will take the passed buf and convert it into a string of |
1296 | * ascii hex digits. The new string is placed onto the skb. |
1297 | */ |
1298 | void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, |
1299 | size_t len) |
1300 | { |
1301 | int i, avail, new_len; |
1302 | unsigned char *ptr; |
1303 | struct sk_buff *skb; |
1304 | static const unsigned char *hex = "0123456789ABCDEF"; |
1305 | |
1306 | if (!ab) |
1307 | return; |
1308 | |
1309 | BUG_ON(!ab->skb); |
1310 | skb = ab->skb; |
1311 | avail = skb_tailroom(skb); |
1312 | new_len = len<<1; |
1313 | if (new_len >= avail) { |
1314 | /* Round the buffer request up to the next multiple */ |
1315 | new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1); |
1316 | avail = audit_expand(ab, new_len); |
1317 | if (!avail) |
1318 | return; |
1319 | } |
1320 | |
1321 | ptr = skb_tail_pointer(skb); |
1322 | for (i=0; i<len; i++) { |
1323 | *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */ |
1324 | *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ |
1325 | } |
1326 | *ptr = 0; |
1327 | skb_put(skb, len << 1); /* new string is twice the old string */ |
1328 | } |
1329 | |
1330 | /* |
1331 | * Format a string of no more than slen characters into the audit buffer, |
1332 | * enclosed in quote marks. |
1333 | */ |
1334 | void audit_log_n_string(struct audit_buffer *ab, const char *string, |
1335 | size_t slen) |
1336 | { |
1337 | int avail, new_len; |
1338 | unsigned char *ptr; |
1339 | struct sk_buff *skb; |
1340 | |
1341 | if (!ab) |
1342 | return; |
1343 | |
1344 | BUG_ON(!ab->skb); |
1345 | skb = ab->skb; |
1346 | avail = skb_tailroom(skb); |
1347 | new_len = slen + 3; /* enclosing quotes + null terminator */ |
1348 | if (new_len > avail) { |
1349 | avail = audit_expand(ab, new_len); |
1350 | if (!avail) |
1351 | return; |
1352 | } |
1353 | ptr = skb_tail_pointer(skb); |
1354 | *ptr++ = '"'; |
1355 | memcpy(ptr, string, slen); |
1356 | ptr += slen; |
1357 | *ptr++ = '"'; |
1358 | *ptr = 0; |
1359 | skb_put(skb, slen + 2); /* don't include null terminator */ |
1360 | } |
1361 | |
1362 | /** |
1363 | * audit_string_contains_control - does a string need to be logged in hex |
1364 | * @string: string to be checked |
1365 | * @len: max length of the string to check |
1366 | */ |
1367 | int audit_string_contains_control(const char *string, size_t len) |
1368 | { |
1369 | const unsigned char *p; |
1370 | for (p = string; p < (const unsigned char *)string + len; p++) { |
1371 | if (*p == '"' || *p < 0x21 || *p > 0x7e) |
1372 | return 1; |
1373 | } |
1374 | return 0; |
1375 | } |
1376 | |
1377 | /** |
1378 | * audit_log_n_untrustedstring - log a string that may contain random characters |
1379 | * @ab: audit_buffer |
1380 | * @len: length of string (not including trailing null) |
1381 | * @string: string to be logged |
1382 | * |
1383 | * This code will escape a string that is passed to it if the string |
1384 | * contains a control character, unprintable character, double quote mark, |
1385 | * or a space. Unescaped strings will start and end with a double quote mark. |
1386 | * Strings that are escaped are printed in hex (2 digits per char). |
1387 | * |
1388 | * The caller specifies the number of characters in the string to log, which may |
1389 | * or may not be the entire string. |
1390 | */ |
1391 | void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string, |
1392 | size_t len) |
1393 | { |
1394 | if (audit_string_contains_control(string, len)) |
1395 | audit_log_n_hex(ab, string, len); |
1396 | else |
1397 | audit_log_n_string(ab, string, len); |
1398 | } |
1399 | |
1400 | /** |
1401 | * audit_log_untrustedstring - log a string that may contain random characters |
1402 | * @ab: audit_buffer |
1403 | * @string: string to be logged |
1404 | * |
1405 | * Same as audit_log_n_untrustedstring(), except that strlen is used to |
1406 | * determine string length. |
1407 | */ |
1408 | void audit_log_untrustedstring(struct audit_buffer *ab, const char *string) |
1409 | { |
1410 | audit_log_n_untrustedstring(ab, string, strlen(string)); |
1411 | } |
1412 | |
1413 | /* This is a helper-function to print the escaped d_path */ |
1414 | void audit_log_d_path(struct audit_buffer *ab, const char *prefix, |
1415 | const struct path *path) |
1416 | { |
1417 | char *p, *pathname; |
1418 | |
1419 | if (prefix) |
1420 | audit_log_format(ab, "%s", prefix); |
1421 | |
1422 | /* We will allow 11 spaces for ' (deleted)' to be appended */ |
1423 | pathname = kmalloc(PATH_MAX+11, ab->gfp_mask); |
1424 | if (!pathname) { |
1425 | audit_log_string(ab, "<no_memory>"); |
1426 | return; |
1427 | } |
1428 | p = d_path(path, pathname, PATH_MAX+11); |
1429 | if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */ |
1430 | /* FIXME: can we save some information here? */ |
1431 | audit_log_string(ab, "<too_long>"); |
1432 | } else |
1433 | audit_log_untrustedstring(ab, p); |
1434 | kfree(pathname); |
1435 | } |
1436 | |
1437 | void audit_log_key(struct audit_buffer *ab, char *key) |
1438 | { |
1439 | audit_log_format(ab, " key="); |
1440 | if (key) |
1441 | audit_log_untrustedstring(ab, key); |
1442 | else |
1443 | audit_log_format(ab, "(null)"); |
1444 | } |
1445 | |
1446 | /** |
1447 | * audit_log_link_denied - report a link restriction denial |
1448 | * @operation: specific link opreation |
1449 | * @link: the path that triggered the restriction |
1450 | */ |
1451 | void audit_log_link_denied(const char *operation, struct path *link) |
1452 | { |
1453 | struct audit_buffer *ab; |
1454 | |
1455 | ab = audit_log_start(current->audit_context, GFP_KERNEL, |
1456 | AUDIT_ANOM_LINK); |
1457 | if (!ab) |
1458 | return; |
1459 | audit_log_format(ab, "op=%s action=denied", operation); |
1460 | audit_log_format(ab, " pid=%d comm=", current->pid); |
1461 | audit_log_untrustedstring(ab, current->comm); |
1462 | audit_log_d_path(ab, " path=", link); |
1463 | audit_log_format(ab, " dev="); |
1464 | audit_log_untrustedstring(ab, link->dentry->d_inode->i_sb->s_id); |
1465 | audit_log_format(ab, " ino=%lu", link->dentry->d_inode->i_ino); |
1466 | audit_log_end(ab); |
1467 | } |
1468 | |
1469 | /** |
1470 | * audit_log_end - end one audit record |
1471 | * @ab: the audit_buffer |
1472 | * |
1473 | * The netlink_* functions cannot be called inside an irq context, so |
1474 | * the audit buffer is placed on a queue and a tasklet is scheduled to |
1475 | * remove them from the queue outside the irq context. May be called in |
1476 | * any context. |
1477 | */ |
1478 | void audit_log_end(struct audit_buffer *ab) |
1479 | { |
1480 | if (!ab) |
1481 | return; |
1482 | if (!audit_rate_check()) { |
1483 | audit_log_lost("rate limit exceeded"); |
1484 | } else { |
1485 | struct nlmsghdr *nlh = nlmsg_hdr(ab->skb); |
1486 | nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0); |
1487 | |
1488 | if (audit_pid) { |
1489 | skb_queue_tail(&audit_skb_queue, ab->skb); |
1490 | wake_up_interruptible(&kauditd_wait); |
1491 | } else { |
1492 | audit_printk_skb(ab->skb); |
1493 | } |
1494 | ab->skb = NULL; |
1495 | } |
1496 | audit_buffer_free(ab); |
1497 | } |
1498 | |
1499 | /** |
1500 | * audit_log - Log an audit record |
1501 | * @ctx: audit context |
1502 | * @gfp_mask: type of allocation |
1503 | * @type: audit message type |
1504 | * @fmt: format string to use |
1505 | * @...: variable parameters matching the format string |
1506 | * |
1507 | * This is a convenience function that calls audit_log_start, |
1508 | * audit_log_vformat, and audit_log_end. It may be called |
1509 | * in any context. |
1510 | */ |
1511 | void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type, |
1512 | const char *fmt, ...) |
1513 | { |
1514 | struct audit_buffer *ab; |
1515 | va_list args; |
1516 | |
1517 | ab = audit_log_start(ctx, gfp_mask, type); |
1518 | if (ab) { |
1519 | va_start(args, fmt); |
1520 | audit_log_vformat(ab, fmt, args); |
1521 | va_end(args); |
1522 | audit_log_end(ab); |
1523 | } |
1524 | } |
1525 | |
1526 | #ifdef CONFIG_SECURITY |
1527 | /** |
1528 | * audit_log_secctx - Converts and logs SELinux context |
1529 | * @ab: audit_buffer |
1530 | * @secid: security number |
1531 | * |
1532 | * This is a helper function that calls security_secid_to_secctx to convert |
1533 | * secid to secctx and then adds the (converted) SELinux context to the audit |
1534 | * log by calling audit_log_format, thus also preventing leak of internal secid |
1535 | * to userspace. If secid cannot be converted audit_panic is called. |
1536 | */ |
1537 | void audit_log_secctx(struct audit_buffer *ab, u32 secid) |
1538 | { |
1539 | u32 len; |
1540 | char *secctx; |
1541 | |
1542 | if (security_secid_to_secctx(secid, &secctx, &len)) { |
1543 | audit_panic("Cannot convert secid to context"); |
1544 | } else { |
1545 | audit_log_format(ab, " obj=%s", secctx); |
1546 | security_release_secctx(secctx, len); |
1547 | } |
1548 | } |
1549 | EXPORT_SYMBOL(audit_log_secctx); |
1550 | #endif |
1551 | |
1552 | EXPORT_SYMBOL(audit_log_start); |
1553 | EXPORT_SYMBOL(audit_log_end); |
1554 | EXPORT_SYMBOL(audit_log_format); |
1555 | EXPORT_SYMBOL(audit_log); |
1556 |
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