Root/kernel/audit.c

1/* audit.c -- Auditing support
2 * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
3 * System-call specific features have moved to auditsc.c
4 *
5 * Copyright 2003-2007 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
65#include "audit.h"
66
67/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
68 * (Initialization happens after skb_init is called.) */
69#define AUDIT_DISABLED -1
70#define AUDIT_UNINITIALIZED 0
71#define AUDIT_INITIALIZED 1
72static int audit_initialized;
73
74#define AUDIT_OFF 0
75#define AUDIT_ON 1
76#define AUDIT_LOCKED 2
77int audit_enabled;
78int audit_ever_enabled;
79
80EXPORT_SYMBOL_GPL(audit_enabled);
81
82/* Default state when kernel boots without any parameters. */
83static int audit_default;
84
85/* If auditing cannot proceed, audit_failure selects what happens. */
86static int audit_failure = AUDIT_FAIL_PRINTK;
87
88/*
89 * If audit records are to be written to the netlink socket, audit_pid
90 * contains the pid of the auditd process and audit_nlk_pid contains
91 * the pid to use to send netlink messages to that process.
92 */
93int audit_pid;
94static int audit_nlk_pid;
95
96/* If audit_rate_limit is non-zero, limit the rate of sending audit records
97 * to that number per second. This prevents DoS attacks, but results in
98 * audit records being dropped. */
99static int audit_rate_limit;
100
101/* Number of outstanding audit_buffers allowed. */
102static int audit_backlog_limit = 64;
103static int audit_backlog_wait_time = 60 * HZ;
104static int audit_backlog_wait_overflow = 0;
105
106/* The identity of the user shutting down the audit system. */
107uid_t audit_sig_uid = -1;
108pid_t audit_sig_pid = -1;
109u32 audit_sig_sid = 0;
110
111/* Records can be lost in several ways:
112   0) [suppressed in audit_alloc]
113   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
114   2) out of memory in audit_log_move [alloc_skb]
115   3) suppressed due to audit_rate_limit
116   4) suppressed due to audit_backlog_limit
117*/
118static atomic_t audit_lost = ATOMIC_INIT(0);
119
120/* The netlink socket. */
121static struct sock *audit_sock;
122
123/* Hash for inode-based rules */
124struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
125
126/* The audit_freelist is a list of pre-allocated audit buffers (if more
127 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
128 * being placed on the freelist). */
129static DEFINE_SPINLOCK(audit_freelist_lock);
130static int audit_freelist_count;
131static LIST_HEAD(audit_freelist);
132
133static struct sk_buff_head audit_skb_queue;
134/* queue of skbs to send to auditd when/if it comes back */
135static struct sk_buff_head audit_skb_hold_queue;
136static struct task_struct *kauditd_task;
137static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
138static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
139
140/* Serialize requests from userspace. */
141DEFINE_MUTEX(audit_cmd_mutex);
142
143/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
144 * audit records. Since printk uses a 1024 byte buffer, this buffer
145 * should be at least that large. */
146#define AUDIT_BUFSIZ 1024
147
148/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
149 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
150#define AUDIT_MAXFREE (2*NR_CPUS)
151
152/* The audit_buffer is used when formatting an audit record. The caller
153 * locks briefly to get the record off the freelist or to allocate the
154 * buffer, and locks briefly to send the buffer to the netlink layer or
155 * to place it on a transmit queue. Multiple audit_buffers can be in
156 * use simultaneously. */
157struct audit_buffer {
158    struct list_head list;
159    struct sk_buff *skb; /* formatted skb ready to send */
160    struct audit_context *ctx; /* NULL or associated context */
161    gfp_t gfp_mask;
162};
163
164struct audit_reply {
165    int pid;
166    struct sk_buff *skb;
167};
168
169static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
170{
171    if (ab) {
172        struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
173        nlh->nlmsg_pid = pid;
174    }
175}
176
177void audit_panic(const char *message)
178{
179    switch (audit_failure)
180    {
181    case AUDIT_FAIL_SILENT:
182        break;
183    case AUDIT_FAIL_PRINTK:
184        if (printk_ratelimit())
185            printk(KERN_ERR "audit: %s\n", message);
186        break;
187    case AUDIT_FAIL_PANIC:
188        /* test audit_pid since printk is always losey, why bother? */
189        if (audit_pid)
190            panic("audit: %s\n", message);
191        break;
192    }
193}
194
195static inline int audit_rate_check(void)
196{
197    static unsigned long last_check = 0;
198    static int messages = 0;
199    static DEFINE_SPINLOCK(lock);
200    unsigned long flags;
201    unsigned long now;
202    unsigned long elapsed;
203    int retval = 0;
204
205    if (!audit_rate_limit) return 1;
206
207    spin_lock_irqsave(&lock, flags);
208    if (++messages < audit_rate_limit) {
209        retval = 1;
210    } else {
211        now = jiffies;
212        elapsed = now - last_check;
213        if (elapsed > HZ) {
214            last_check = now;
215            messages = 0;
216            retval = 1;
217        }
218    }
219    spin_unlock_irqrestore(&lock, flags);
220
221    return retval;
222}
223
224/**
225 * audit_log_lost - conditionally log lost audit message event
226 * @message: the message stating reason for lost audit message
227 *
228 * Emit at least 1 message per second, even if audit_rate_check is
229 * throttling.
230 * Always increment the lost messages counter.
231*/
232void audit_log_lost(const char *message)
233{
234    static unsigned long last_msg = 0;
235    static DEFINE_SPINLOCK(lock);
236    unsigned long flags;
237    unsigned long now;
238    int print;
239
240    atomic_inc(&audit_lost);
241
242    print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
243
244    if (!print) {
245        spin_lock_irqsave(&lock, flags);
246        now = jiffies;
247        if (now - last_msg > HZ) {
248            print = 1;
249            last_msg = now;
250        }
251        spin_unlock_irqrestore(&lock, flags);
252    }
253
254    if (print) {
255        if (printk_ratelimit())
256            printk(KERN_WARNING
257                "audit: audit_lost=%d audit_rate_limit=%d "
258                "audit_backlog_limit=%d\n",
259                atomic_read(&audit_lost),
260                audit_rate_limit,
261                audit_backlog_limit);
262        audit_panic(message);
263    }
264}
265
266static int audit_log_config_change(char *function_name, int new, int old,
267                   uid_t loginuid, u32 sessionid, u32 sid,
268                   int allow_changes)
269{
270    struct audit_buffer *ab;
271    int rc = 0;
272
273    ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
274    audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
275             old, loginuid, sessionid);
276    if (sid) {
277        char *ctx = NULL;
278        u32 len;
279
280        rc = security_secid_to_secctx(sid, &ctx, &len);
281        if (rc) {
282            audit_log_format(ab, " sid=%u", sid);
283            allow_changes = 0; /* Something weird, deny request */
284        } else {
285            audit_log_format(ab, " subj=%s", ctx);
286            security_release_secctx(ctx, len);
287        }
288    }
289    audit_log_format(ab, " res=%d", allow_changes);
290    audit_log_end(ab);
291    return rc;
292}
293
294static int audit_do_config_change(char *function_name, int *to_change,
295                  int new, uid_t loginuid, u32 sessionid,
296                  u32 sid)
297{
298    int allow_changes, rc = 0, old = *to_change;
299
300    /* check if we are locked */
301    if (audit_enabled == AUDIT_LOCKED)
302        allow_changes = 0;
303    else
304        allow_changes = 1;
305
306    if (audit_enabled != AUDIT_OFF) {
307        rc = audit_log_config_change(function_name, new, old, loginuid,
308                         sessionid, sid, allow_changes);
309        if (rc)
310            allow_changes = 0;
311    }
312
313    /* If we are allowed, make the change */
314    if (allow_changes == 1)
315        *to_change = new;
316    /* Not allowed, update reason */
317    else if (rc == 0)
318        rc = -EPERM;
319    return rc;
320}
321
322static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
323                u32 sid)
324{
325    return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
326                      limit, loginuid, sessionid, sid);
327}
328
329static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
330                   u32 sid)
331{
332    return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
333                      limit, loginuid, sessionid, sid);
334}
335
336static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
337{
338    int rc;
339    if (state < AUDIT_OFF || state > AUDIT_LOCKED)
340        return -EINVAL;
341
342    rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
343                     loginuid, sessionid, sid);
344
345    if (!rc)
346        audit_ever_enabled |= !!state;
347
348    return rc;
349}
350
351static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
352{
353    if (state != AUDIT_FAIL_SILENT
354        && state != AUDIT_FAIL_PRINTK
355        && state != AUDIT_FAIL_PANIC)
356        return -EINVAL;
357
358    return audit_do_config_change("audit_failure", &audit_failure, state,
359                      loginuid, sessionid, sid);
360}
361
362/*
363 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
364 * already have been sent via prink/syslog and so if these messages are dropped
365 * it is not a huge concern since we already passed the audit_log_lost()
366 * notification and stuff. This is just nice to get audit messages during
367 * boot before auditd is running or messages generated while auditd is stopped.
368 * This only holds messages is audit_default is set, aka booting with audit=1
369 * or building your kernel that way.
370 */
371static void audit_hold_skb(struct sk_buff *skb)
372{
373    if (audit_default &&
374        skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
375        skb_queue_tail(&audit_skb_hold_queue, skb);
376    else
377        kfree_skb(skb);
378}
379
380/*
381 * For one reason or another this nlh isn't getting delivered to the userspace
382 * audit daemon, just send it to printk.
383 */
384static void audit_printk_skb(struct sk_buff *skb)
385{
386    struct nlmsghdr *nlh = nlmsg_hdr(skb);
387    char *data = NLMSG_DATA(nlh);
388
389    if (nlh->nlmsg_type != AUDIT_EOE) {
390        if (printk_ratelimit())
391            printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
392        else
393            audit_log_lost("printk limit exceeded\n");
394    }
395
396    audit_hold_skb(skb);
397}
398
399static void kauditd_send_skb(struct sk_buff *skb)
400{
401    int err;
402    /* take a reference in case we can't send it and we want to hold it */
403    skb_get(skb);
404    err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
405    if (err < 0) {
406        BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
407        printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
408        audit_log_lost("auditd disappeared\n");
409        audit_pid = 0;
410        /* we might get lucky and get this in the next auditd */
411        audit_hold_skb(skb);
412    } else
413        /* drop the extra reference if sent ok */
414        consume_skb(skb);
415}
416
417static int kauditd_thread(void *dummy)
418{
419    struct sk_buff *skb;
420
421    set_freezable();
422    while (!kthread_should_stop()) {
423        /*
424         * if auditd just started drain the queue of messages already
425         * sent to syslog/printk. remember loss here is ok. we already
426         * called audit_log_lost() if it didn't go out normally. so the
427         * race between the skb_dequeue and the next check for audit_pid
428         * doesn't matter.
429         *
430         * if you ever find kauditd to be too slow we can get a perf win
431         * by doing our own locking and keeping better track if there
432         * are messages in this queue. I don't see the need now, but
433         * in 5 years when I want to play with this again I'll see this
434         * note and still have no friggin idea what i'm thinking today.
435         */
436        if (audit_default && audit_pid) {
437            skb = skb_dequeue(&audit_skb_hold_queue);
438            if (unlikely(skb)) {
439                while (skb && audit_pid) {
440                    kauditd_send_skb(skb);
441                    skb = skb_dequeue(&audit_skb_hold_queue);
442                }
443            }
444        }
445
446        skb = skb_dequeue(&audit_skb_queue);
447        wake_up(&audit_backlog_wait);
448        if (skb) {
449            if (audit_pid)
450                kauditd_send_skb(skb);
451            else
452                audit_printk_skb(skb);
453        } else {
454            DECLARE_WAITQUEUE(wait, current);
455            set_current_state(TASK_INTERRUPTIBLE);
456            add_wait_queue(&kauditd_wait, &wait);
457
458            if (!skb_queue_len(&audit_skb_queue)) {
459                try_to_freeze();
460                schedule();
461            }
462
463            __set_current_state(TASK_RUNNING);
464            remove_wait_queue(&kauditd_wait, &wait);
465        }
466    }
467    return 0;
468}
469
470static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
471{
472    struct task_struct *tsk;
473    int err;
474
475    rcu_read_lock();
476    tsk = find_task_by_vpid(pid);
477    if (!tsk) {
478        rcu_read_unlock();
479        return -ESRCH;
480    }
481    get_task_struct(tsk);
482    rcu_read_unlock();
483    err = tty_audit_push_task(tsk, loginuid, sessionid);
484    put_task_struct(tsk);
485    return err;
486}
487
488int audit_send_list(void *_dest)
489{
490    struct audit_netlink_list *dest = _dest;
491    int pid = dest->pid;
492    struct sk_buff *skb;
493
494    /* wait for parent to finish and send an ACK */
495    mutex_lock(&audit_cmd_mutex);
496    mutex_unlock(&audit_cmd_mutex);
497
498    while ((skb = __skb_dequeue(&dest->q)) != NULL)
499        netlink_unicast(audit_sock, skb, pid, 0);
500
501    kfree(dest);
502
503    return 0;
504}
505
506struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
507                 int multi, const void *payload, int size)
508{
509    struct sk_buff *skb;
510    struct nlmsghdr *nlh;
511    void *data;
512    int flags = multi ? NLM_F_MULTI : 0;
513    int t = done ? NLMSG_DONE : type;
514
515    skb = nlmsg_new(size, GFP_KERNEL);
516    if (!skb)
517        return NULL;
518
519    nlh = NLMSG_NEW(skb, pid, seq, t, size, flags);
520    data = NLMSG_DATA(nlh);
521    memcpy(data, payload, size);
522    return skb;
523
524nlmsg_failure: /* Used by NLMSG_NEW */
525    if (skb)
526        kfree_skb(skb);
527    return NULL;
528}
529
530static int audit_send_reply_thread(void *arg)
531{
532    struct audit_reply *reply = (struct audit_reply *)arg;
533
534    mutex_lock(&audit_cmd_mutex);
535    mutex_unlock(&audit_cmd_mutex);
536
537    /* Ignore failure. It'll only happen if the sender goes away,
538       because our timeout is set to infinite. */
539    netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
540    kfree(reply);
541    return 0;
542}
543/**
544 * audit_send_reply - send an audit reply message via netlink
545 * @pid: process id to send reply to
546 * @seq: sequence number
547 * @type: audit message type
548 * @done: done (last) flag
549 * @multi: multi-part message flag
550 * @payload: payload data
551 * @size: payload size
552 *
553 * Allocates an skb, builds the netlink message, and sends it to the pid.
554 * No failure notifications.
555 */
556static void audit_send_reply(int pid, int seq, int type, int done, int multi,
557                 const void *payload, int size)
558{
559    struct sk_buff *skb;
560    struct task_struct *tsk;
561    struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
562                        GFP_KERNEL);
563
564    if (!reply)
565        return;
566
567    skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
568    if (!skb)
569        goto out;
570
571    reply->pid = pid;
572    reply->skb = skb;
573
574    tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
575    if (!IS_ERR(tsk))
576        return;
577    kfree_skb(skb);
578out:
579    kfree(reply);
580}
581
582/*
583 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
584 * control messages.
585 */
586static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
587{
588    int err = 0;
589
590    switch (msg_type) {
591    case AUDIT_GET:
592    case AUDIT_LIST:
593    case AUDIT_LIST_RULES:
594    case AUDIT_SET:
595    case AUDIT_ADD:
596    case AUDIT_ADD_RULE:
597    case AUDIT_DEL:
598    case AUDIT_DEL_RULE:
599    case AUDIT_SIGNAL_INFO:
600    case AUDIT_TTY_GET:
601    case AUDIT_TTY_SET:
602    case AUDIT_TRIM:
603    case AUDIT_MAKE_EQUIV:
604        if (!capable(CAP_AUDIT_CONTROL))
605            err = -EPERM;
606        break;
607    case AUDIT_USER:
608    case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
609    case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
610        if (!capable(CAP_AUDIT_WRITE))
611            err = -EPERM;
612        break;
613    default: /* bad msg */
614        err = -EINVAL;
615    }
616
617    return err;
618}
619
620static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
621                     u32 pid, u32 uid, uid_t auid, u32 ses,
622                     u32 sid)
623{
624    int rc = 0;
625    char *ctx = NULL;
626    u32 len;
627
628    if (!audit_enabled) {
629        *ab = NULL;
630        return rc;
631    }
632
633    *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
634    audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
635             pid, uid, auid, ses);
636    if (sid) {
637        rc = security_secid_to_secctx(sid, &ctx, &len);
638        if (rc)
639            audit_log_format(*ab, " ssid=%u", sid);
640        else {
641            audit_log_format(*ab, " subj=%s", ctx);
642            security_release_secctx(ctx, len);
643        }
644    }
645
646    return rc;
647}
648
649static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
650{
651    u32 uid, pid, seq, sid;
652    void *data;
653    struct audit_status *status_get, status_set;
654    int err;
655    struct audit_buffer *ab;
656    u16 msg_type = nlh->nlmsg_type;
657    uid_t loginuid; /* loginuid of sender */
658    u32 sessionid;
659    struct audit_sig_info *sig_data;
660    char *ctx = NULL;
661    u32 len;
662
663    err = audit_netlink_ok(skb, msg_type);
664    if (err)
665        return err;
666
667    /* As soon as there's any sign of userspace auditd,
668     * start kauditd to talk to it */
669    if (!kauditd_task)
670        kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
671    if (IS_ERR(kauditd_task)) {
672        err = PTR_ERR(kauditd_task);
673        kauditd_task = NULL;
674        return err;
675    }
676
677    pid = NETLINK_CREDS(skb)->pid;
678    uid = NETLINK_CREDS(skb)->uid;
679    loginuid = audit_get_loginuid(current);
680    sessionid = audit_get_sessionid(current);
681    security_task_getsecid(current, &sid);
682    seq = nlh->nlmsg_seq;
683    data = NLMSG_DATA(nlh);
684
685    switch (msg_type) {
686    case AUDIT_GET:
687        status_set.enabled = audit_enabled;
688        status_set.failure = audit_failure;
689        status_set.pid = audit_pid;
690        status_set.rate_limit = audit_rate_limit;
691        status_set.backlog_limit = audit_backlog_limit;
692        status_set.lost = atomic_read(&audit_lost);
693        status_set.backlog = skb_queue_len(&audit_skb_queue);
694        audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
695                 &status_set, sizeof(status_set));
696        break;
697    case AUDIT_SET:
698        if (nlh->nlmsg_len < sizeof(struct audit_status))
699            return -EINVAL;
700        status_get = (struct audit_status *)data;
701        if (status_get->mask & AUDIT_STATUS_ENABLED) {
702            err = audit_set_enabled(status_get->enabled,
703                        loginuid, sessionid, sid);
704            if (err < 0)
705                return err;
706        }
707        if (status_get->mask & AUDIT_STATUS_FAILURE) {
708            err = audit_set_failure(status_get->failure,
709                        loginuid, sessionid, sid);
710            if (err < 0)
711                return err;
712        }
713        if (status_get->mask & AUDIT_STATUS_PID) {
714            int new_pid = status_get->pid;
715
716            if (audit_enabled != AUDIT_OFF)
717                audit_log_config_change("audit_pid", new_pid,
718                            audit_pid, loginuid,
719                            sessionid, sid, 1);
720
721            audit_pid = new_pid;
722            audit_nlk_pid = NETLINK_CB(skb).pid;
723        }
724        if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
725            err = audit_set_rate_limit(status_get->rate_limit,
726                           loginuid, sessionid, sid);
727            if (err < 0)
728                return err;
729        }
730        if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
731            err = audit_set_backlog_limit(status_get->backlog_limit,
732                              loginuid, sessionid, sid);
733        break;
734    case AUDIT_USER:
735    case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
736    case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
737        if (!audit_enabled && msg_type != AUDIT_USER_AVC)
738            return 0;
739
740        err = audit_filter_user(&NETLINK_CB(skb));
741        if (err == 1) {
742            err = 0;
743            if (msg_type == AUDIT_USER_TTY) {
744                err = audit_prepare_user_tty(pid, loginuid,
745                                 sessionid);
746                if (err)
747                    break;
748            }
749            audit_log_common_recv_msg(&ab, msg_type, pid, uid,
750                          loginuid, sessionid, sid);
751
752            if (msg_type != AUDIT_USER_TTY)
753                audit_log_format(ab, " msg='%.1024s'",
754                         (char *)data);
755            else {
756                int size;
757
758                audit_log_format(ab, " msg=");
759                size = nlmsg_len(nlh);
760                if (size > 0 &&
761                    ((unsigned char *)data)[size - 1] == '\0')
762                    size--;
763                audit_log_n_untrustedstring(ab, data, size);
764            }
765            audit_set_pid(ab, pid);
766            audit_log_end(ab);
767        }
768        break;
769    case AUDIT_ADD:
770    case AUDIT_DEL:
771        if (nlmsg_len(nlh) < sizeof(struct audit_rule))
772            return -EINVAL;
773        if (audit_enabled == AUDIT_LOCKED) {
774            audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
775                          uid, loginuid, sessionid, sid);
776
777            audit_log_format(ab, " audit_enabled=%d res=0",
778                     audit_enabled);
779            audit_log_end(ab);
780            return -EPERM;
781        }
782        /* fallthrough */
783    case AUDIT_LIST:
784        err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
785                       uid, seq, data, nlmsg_len(nlh),
786                       loginuid, sessionid, sid);
787        break;
788    case AUDIT_ADD_RULE:
789    case AUDIT_DEL_RULE:
790        if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
791            return -EINVAL;
792        if (audit_enabled == AUDIT_LOCKED) {
793            audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
794                          uid, loginuid, sessionid, sid);
795
796            audit_log_format(ab, " audit_enabled=%d res=0",
797                     audit_enabled);
798            audit_log_end(ab);
799            return -EPERM;
800        }
801        /* fallthrough */
802    case AUDIT_LIST_RULES:
803        err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
804                       uid, seq, data, nlmsg_len(nlh),
805                       loginuid, sessionid, sid);
806        break;
807    case AUDIT_TRIM:
808        audit_trim_trees();
809
810        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
811                      uid, loginuid, sessionid, sid);
812
813        audit_log_format(ab, " op=trim res=1");
814        audit_log_end(ab);
815        break;
816    case AUDIT_MAKE_EQUIV: {
817        void *bufp = data;
818        u32 sizes[2];
819        size_t msglen = nlmsg_len(nlh);
820        char *old, *new;
821
822        err = -EINVAL;
823        if (msglen < 2 * sizeof(u32))
824            break;
825        memcpy(sizes, bufp, 2 * sizeof(u32));
826        bufp += 2 * sizeof(u32);
827        msglen -= 2 * sizeof(u32);
828        old = audit_unpack_string(&bufp, &msglen, sizes[0]);
829        if (IS_ERR(old)) {
830            err = PTR_ERR(old);
831            break;
832        }
833        new = audit_unpack_string(&bufp, &msglen, sizes[1]);
834        if (IS_ERR(new)) {
835            err = PTR_ERR(new);
836            kfree(old);
837            break;
838        }
839        /* OK, here comes... */
840        err = audit_tag_tree(old, new);
841
842        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
843                      uid, loginuid, sessionid, sid);
844
845        audit_log_format(ab, " op=make_equiv old=");
846        audit_log_untrustedstring(ab, old);
847        audit_log_format(ab, " new=");
848        audit_log_untrustedstring(ab, new);
849        audit_log_format(ab, " res=%d", !err);
850        audit_log_end(ab);
851        kfree(old);
852        kfree(new);
853        break;
854    }
855    case AUDIT_SIGNAL_INFO:
856        len = 0;
857        if (audit_sig_sid) {
858            err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
859            if (err)
860                return err;
861        }
862        sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
863        if (!sig_data) {
864            if (audit_sig_sid)
865                security_release_secctx(ctx, len);
866            return -ENOMEM;
867        }
868        sig_data->uid = audit_sig_uid;
869        sig_data->pid = audit_sig_pid;
870        if (audit_sig_sid) {
871            memcpy(sig_data->ctx, ctx, len);
872            security_release_secctx(ctx, len);
873        }
874        audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
875                0, 0, sig_data, sizeof(*sig_data) + len);
876        kfree(sig_data);
877        break;
878    case AUDIT_TTY_GET: {
879        struct audit_tty_status s;
880        struct task_struct *tsk;
881        unsigned long flags;
882
883        rcu_read_lock();
884        tsk = find_task_by_vpid(pid);
885        if (tsk && lock_task_sighand(tsk, &flags)) {
886            s.enabled = tsk->signal->audit_tty != 0;
887            unlock_task_sighand(tsk, &flags);
888        } else
889            err = -ESRCH;
890        rcu_read_unlock();
891
892        if (!err)
893            audit_send_reply(NETLINK_CB(skb).pid, seq,
894                     AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
895        break;
896    }
897    case AUDIT_TTY_SET: {
898        struct audit_tty_status *s;
899        struct task_struct *tsk;
900        unsigned long flags;
901
902        if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
903            return -EINVAL;
904        s = data;
905        if (s->enabled != 0 && s->enabled != 1)
906            return -EINVAL;
907        rcu_read_lock();
908        tsk = find_task_by_vpid(pid);
909        if (tsk && lock_task_sighand(tsk, &flags)) {
910            tsk->signal->audit_tty = s->enabled != 0;
911            unlock_task_sighand(tsk, &flags);
912        } else
913            err = -ESRCH;
914        rcu_read_unlock();
915        break;
916    }
917    default:
918        err = -EINVAL;
919        break;
920    }
921
922    return err < 0 ? err : 0;
923}
924
925/*
926 * Get message from skb. Each message is processed by audit_receive_msg.
927 * Malformed skbs with wrong length are discarded silently.
928 */
929static void audit_receive_skb(struct sk_buff *skb)
930{
931    struct nlmsghdr *nlh;
932    /*
933     * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
934     * if the nlmsg_len was not aligned
935     */
936    int len;
937    int err;
938
939    nlh = nlmsg_hdr(skb);
940    len = skb->len;
941
942    while (NLMSG_OK(nlh, len)) {
943        err = audit_receive_msg(skb, nlh);
944        /* if err or if this message says it wants a response */
945        if (err || (nlh->nlmsg_flags & NLM_F_ACK))
946            netlink_ack(skb, nlh, err);
947
948        nlh = NLMSG_NEXT(nlh, len);
949    }
950}
951
952/* Receive messages from netlink socket. */
953static void audit_receive(struct sk_buff *skb)
954{
955    mutex_lock(&audit_cmd_mutex);
956    audit_receive_skb(skb);
957    mutex_unlock(&audit_cmd_mutex);
958}
959
960/* Initialize audit support at boot time. */
961static int __init audit_init(void)
962{
963    int i;
964
965    if (audit_initialized == AUDIT_DISABLED)
966        return 0;
967
968    printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
969           audit_default ? "enabled" : "disabled");
970    audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
971                       audit_receive, NULL, THIS_MODULE);
972    if (!audit_sock)
973        audit_panic("cannot initialize netlink socket");
974    else
975        audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
976
977    skb_queue_head_init(&audit_skb_queue);
978    skb_queue_head_init(&audit_skb_hold_queue);
979    audit_initialized = AUDIT_INITIALIZED;
980    audit_enabled = audit_default;
981    audit_ever_enabled |= !!audit_default;
982
983    audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
984
985    for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
986        INIT_LIST_HEAD(&audit_inode_hash[i]);
987
988    return 0;
989}
990__initcall(audit_init);
991
992/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
993static int __init audit_enable(char *str)
994{
995    audit_default = !!simple_strtol(str, NULL, 0);
996    if (!audit_default)
997        audit_initialized = AUDIT_DISABLED;
998
999    printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
1000
1001    if (audit_initialized == AUDIT_INITIALIZED) {
1002        audit_enabled = audit_default;
1003        audit_ever_enabled |= !!audit_default;
1004    } else if (audit_initialized == AUDIT_UNINITIALIZED) {
1005        printk(" (after initialization)");
1006    } else {
1007        printk(" (until reboot)");
1008    }
1009    printk("\n");
1010
1011    return 1;
1012}
1013
1014__setup("audit=", audit_enable);
1015
1016static void audit_buffer_free(struct audit_buffer *ab)
1017{
1018    unsigned long flags;
1019
1020    if (!ab)
1021        return;
1022
1023    if (ab->skb)
1024        kfree_skb(ab->skb);
1025
1026    spin_lock_irqsave(&audit_freelist_lock, flags);
1027    if (audit_freelist_count > AUDIT_MAXFREE)
1028        kfree(ab);
1029    else {
1030        audit_freelist_count++;
1031        list_add(&ab->list, &audit_freelist);
1032    }
1033    spin_unlock_irqrestore(&audit_freelist_lock, flags);
1034}
1035
1036static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1037                        gfp_t gfp_mask, int type)
1038{
1039    unsigned long flags;
1040    struct audit_buffer *ab = NULL;
1041    struct nlmsghdr *nlh;
1042
1043    spin_lock_irqsave(&audit_freelist_lock, flags);
1044    if (!list_empty(&audit_freelist)) {
1045        ab = list_entry(audit_freelist.next,
1046                struct audit_buffer, list);
1047        list_del(&ab->list);
1048        --audit_freelist_count;
1049    }
1050    spin_unlock_irqrestore(&audit_freelist_lock, flags);
1051
1052    if (!ab) {
1053        ab = kmalloc(sizeof(*ab), gfp_mask);
1054        if (!ab)
1055            goto err;
1056    }
1057
1058    ab->ctx = ctx;
1059    ab->gfp_mask = gfp_mask;
1060
1061    ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1062    if (!ab->skb)
1063        goto nlmsg_failure;
1064
1065    nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0);
1066
1067    return ab;
1068
1069nlmsg_failure: /* Used by NLMSG_NEW */
1070    kfree_skb(ab->skb);
1071    ab->skb = NULL;
1072err:
1073    audit_buffer_free(ab);
1074    return NULL;
1075}
1076
1077/**
1078 * audit_serial - compute a serial number for the audit record
1079 *
1080 * Compute a serial number for the audit record. Audit records are
1081 * written to user-space as soon as they are generated, so a complete
1082 * audit record may be written in several pieces. The timestamp of the
1083 * record and this serial number are used by the user-space tools to
1084 * determine which pieces belong to the same audit record. The
1085 * (timestamp,serial) tuple is unique for each syscall and is live from
1086 * syscall entry to syscall exit.
1087 *
1088 * NOTE: Another possibility is to store the formatted records off the
1089 * audit context (for those records that have a context), and emit them
1090 * all at syscall exit. However, this could delay the reporting of
1091 * significant errors until syscall exit (or never, if the system
1092 * halts).
1093 */
1094unsigned int audit_serial(void)
1095{
1096    static DEFINE_SPINLOCK(serial_lock);
1097    static unsigned int serial = 0;
1098
1099    unsigned long flags;
1100    unsigned int ret;
1101
1102    spin_lock_irqsave(&serial_lock, flags);
1103    do {
1104        ret = ++serial;
1105    } while (unlikely(!ret));
1106    spin_unlock_irqrestore(&serial_lock, flags);
1107
1108    return ret;
1109}
1110
1111static inline void audit_get_stamp(struct audit_context *ctx,
1112                   struct timespec *t, unsigned int *serial)
1113{
1114    if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1115        *t = CURRENT_TIME;
1116        *serial = audit_serial();
1117    }
1118}
1119
1120/* Obtain an audit buffer. This routine does locking to obtain the
1121 * audit buffer, but then no locking is required for calls to
1122 * audit_log_*format. If the tsk is a task that is currently in a
1123 * syscall, then the syscall is marked as auditable and an audit record
1124 * will be written at syscall exit. If there is no associated task, tsk
1125 * should be NULL. */
1126
1127/**
1128 * audit_log_start - obtain an audit buffer
1129 * @ctx: audit_context (may be NULL)
1130 * @gfp_mask: type of allocation
1131 * @type: audit message type
1132 *
1133 * Returns audit_buffer pointer on success or NULL on error.
1134 *
1135 * Obtain an audit buffer. This routine does locking to obtain the
1136 * audit buffer, but then no locking is required for calls to
1137 * audit_log_*format. If the task (ctx) is a task that is currently in a
1138 * syscall, then the syscall is marked as auditable and an audit record
1139 * will be written at syscall exit. If there is no associated task, then
1140 * task context (ctx) should be NULL.
1141 */
1142struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1143                     int type)
1144{
1145    struct audit_buffer *ab = NULL;
1146    struct timespec t;
1147    unsigned int uninitialized_var(serial);
1148    int reserve;
1149    unsigned long timeout_start = jiffies;
1150
1151    if (audit_initialized != AUDIT_INITIALIZED)
1152        return NULL;
1153
1154    if (unlikely(audit_filter_type(type)))
1155        return NULL;
1156
1157    if (gfp_mask & __GFP_WAIT)
1158        reserve = 0;
1159    else
1160        reserve = 5; /* Allow atomic callers to go up to five
1161                entries over the normal backlog limit */
1162
1163    while (audit_backlog_limit
1164           && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1165        if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1166            && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1167
1168            /* Wait for auditd to drain the queue a little */
1169            DECLARE_WAITQUEUE(wait, current);
1170            set_current_state(TASK_INTERRUPTIBLE);
1171            add_wait_queue(&audit_backlog_wait, &wait);
1172
1173            if (audit_backlog_limit &&
1174                skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1175                schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1176
1177            __set_current_state(TASK_RUNNING);
1178            remove_wait_queue(&audit_backlog_wait, &wait);
1179            continue;
1180        }
1181        if (audit_rate_check() && printk_ratelimit())
1182            printk(KERN_WARNING
1183                   "audit: audit_backlog=%d > "
1184                   "audit_backlog_limit=%d\n",
1185                   skb_queue_len(&audit_skb_queue),
1186                   audit_backlog_limit);
1187        audit_log_lost("backlog limit exceeded");
1188        audit_backlog_wait_time = audit_backlog_wait_overflow;
1189        wake_up(&audit_backlog_wait);
1190        return NULL;
1191    }
1192
1193    ab = audit_buffer_alloc(ctx, gfp_mask, type);
1194    if (!ab) {
1195        audit_log_lost("out of memory in audit_log_start");
1196        return NULL;
1197    }
1198
1199    audit_get_stamp(ab->ctx, &t, &serial);
1200
1201    audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1202             t.tv_sec, t.tv_nsec/1000000, serial);
1203    return ab;
1204}
1205
1206/**
1207 * audit_expand - expand skb in the audit buffer
1208 * @ab: audit_buffer
1209 * @extra: space to add at tail of the skb
1210 *
1211 * Returns 0 (no space) on failed expansion, or available space if
1212 * successful.
1213 */
1214static inline int audit_expand(struct audit_buffer *ab, int extra)
1215{
1216    struct sk_buff *skb = ab->skb;
1217    int oldtail = skb_tailroom(skb);
1218    int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1219    int newtail = skb_tailroom(skb);
1220
1221    if (ret < 0) {
1222        audit_log_lost("out of memory in audit_expand");
1223        return 0;
1224    }
1225
1226    skb->truesize += newtail - oldtail;
1227    return newtail;
1228}
1229
1230/*
1231 * Format an audit message into the audit buffer. If there isn't enough
1232 * room in the audit buffer, more room will be allocated and vsnprint
1233 * will be called a second time. Currently, we assume that a printk
1234 * can't format message larger than 1024 bytes, so we don't either.
1235 */
1236static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1237                  va_list args)
1238{
1239    int len, avail;
1240    struct sk_buff *skb;
1241    va_list args2;
1242
1243    if (!ab)
1244        return;
1245
1246    BUG_ON(!ab->skb);
1247    skb = ab->skb;
1248    avail = skb_tailroom(skb);
1249    if (avail == 0) {
1250        avail = audit_expand(ab, AUDIT_BUFSIZ);
1251        if (!avail)
1252            goto out;
1253    }
1254    va_copy(args2, args);
1255    len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1256    if (len >= avail) {
1257        /* The printk buffer is 1024 bytes long, so if we get
1258         * here and AUDIT_BUFSIZ is at least 1024, then we can
1259         * log everything that printk could have logged. */
1260        avail = audit_expand(ab,
1261            max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1262        if (!avail)
1263            goto out_va_end;
1264        len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1265    }
1266    if (len > 0)
1267        skb_put(skb, len);
1268out_va_end:
1269    va_end(args2);
1270out:
1271    return;
1272}
1273
1274/**
1275 * audit_log_format - format a message into the audit buffer.
1276 * @ab: audit_buffer
1277 * @fmt: format string
1278 * @...: optional parameters matching @fmt string
1279 *
1280 * All the work is done in audit_log_vformat.
1281 */
1282void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1283{
1284    va_list args;
1285
1286    if (!ab)
1287        return;
1288    va_start(args, fmt);
1289    audit_log_vformat(ab, fmt, args);
1290    va_end(args);
1291}
1292
1293/**
1294 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1295 * @ab: the audit_buffer
1296 * @buf: buffer to convert to hex
1297 * @len: length of @buf to be converted
1298 *
1299 * No return value; failure to expand is silently ignored.
1300 *
1301 * This function will take the passed buf and convert it into a string of
1302 * ascii hex digits. The new string is placed onto the skb.
1303 */
1304void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1305        size_t len)
1306{
1307    int i, avail, new_len;
1308    unsigned char *ptr;
1309    struct sk_buff *skb;
1310    static const unsigned char *hex = "0123456789ABCDEF";
1311
1312    if (!ab)
1313        return;
1314
1315    BUG_ON(!ab->skb);
1316    skb = ab->skb;
1317    avail = skb_tailroom(skb);
1318    new_len = len<<1;
1319    if (new_len >= avail) {
1320        /* Round the buffer request up to the next multiple */
1321        new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1322        avail = audit_expand(ab, new_len);
1323        if (!avail)
1324            return;
1325    }
1326
1327    ptr = skb_tail_pointer(skb);
1328    for (i=0; i<len; i++) {
1329        *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1330        *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1331    }
1332    *ptr = 0;
1333    skb_put(skb, len << 1); /* new string is twice the old string */
1334}
1335
1336/*
1337 * Format a string of no more than slen characters into the audit buffer,
1338 * enclosed in quote marks.
1339 */
1340void audit_log_n_string(struct audit_buffer *ab, const char *string,
1341            size_t slen)
1342{
1343    int avail, new_len;
1344    unsigned char *ptr;
1345    struct sk_buff *skb;
1346
1347    if (!ab)
1348        return;
1349
1350    BUG_ON(!ab->skb);
1351    skb = ab->skb;
1352    avail = skb_tailroom(skb);
1353    new_len = slen + 3; /* enclosing quotes + null terminator */
1354    if (new_len > avail) {
1355        avail = audit_expand(ab, new_len);
1356        if (!avail)
1357            return;
1358    }
1359    ptr = skb_tail_pointer(skb);
1360    *ptr++ = '"';
1361    memcpy(ptr, string, slen);
1362    ptr += slen;
1363    *ptr++ = '"';
1364    *ptr = 0;
1365    skb_put(skb, slen + 2); /* don't include null terminator */
1366}
1367
1368/**
1369 * audit_string_contains_control - does a string need to be logged in hex
1370 * @string: string to be checked
1371 * @len: max length of the string to check
1372 */
1373int audit_string_contains_control(const char *string, size_t len)
1374{
1375    const unsigned char *p;
1376    for (p = string; p < (const unsigned char *)string + len; p++) {
1377        if (*p == '"' || *p < 0x21 || *p > 0x7e)
1378            return 1;
1379    }
1380    return 0;
1381}
1382
1383/**
1384 * audit_log_n_untrustedstring - log a string that may contain random characters
1385 * @ab: audit_buffer
1386 * @len: length of string (not including trailing null)
1387 * @string: string to be logged
1388 *
1389 * This code will escape a string that is passed to it if the string
1390 * contains a control character, unprintable character, double quote mark,
1391 * or a space. Unescaped strings will start and end with a double quote mark.
1392 * Strings that are escaped are printed in hex (2 digits per char).
1393 *
1394 * The caller specifies the number of characters in the string to log, which may
1395 * or may not be the entire string.
1396 */
1397void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1398                 size_t len)
1399{
1400    if (audit_string_contains_control(string, len))
1401        audit_log_n_hex(ab, string, len);
1402    else
1403        audit_log_n_string(ab, string, len);
1404}
1405
1406/**
1407 * audit_log_untrustedstring - log a string that may contain random characters
1408 * @ab: audit_buffer
1409 * @string: string to be logged
1410 *
1411 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1412 * determine string length.
1413 */
1414void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1415{
1416    audit_log_n_untrustedstring(ab, string, strlen(string));
1417}
1418
1419/* This is a helper-function to print the escaped d_path */
1420void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1421              const struct path *path)
1422{
1423    char *p, *pathname;
1424
1425    if (prefix)
1426        audit_log_format(ab, "%s", prefix);
1427
1428    /* We will allow 11 spaces for ' (deleted)' to be appended */
1429    pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1430    if (!pathname) {
1431        audit_log_string(ab, "<no_memory>");
1432        return;
1433    }
1434    p = d_path(path, pathname, PATH_MAX+11);
1435    if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1436        /* FIXME: can we save some information here? */
1437        audit_log_string(ab, "<too_long>");
1438    } else
1439        audit_log_untrustedstring(ab, p);
1440    kfree(pathname);
1441}
1442
1443void audit_log_key(struct audit_buffer *ab, char *key)
1444{
1445    audit_log_format(ab, " key=");
1446    if (key)
1447        audit_log_untrustedstring(ab, key);
1448    else
1449        audit_log_format(ab, "(null)");
1450}
1451
1452/**
1453 * audit_log_end - end one audit record
1454 * @ab: the audit_buffer
1455 *
1456 * The netlink_* functions cannot be called inside an irq context, so
1457 * the audit buffer is placed on a queue and a tasklet is scheduled to
1458 * remove them from the queue outside the irq context. May be called in
1459 * any context.
1460 */
1461void audit_log_end(struct audit_buffer *ab)
1462{
1463    if (!ab)
1464        return;
1465    if (!audit_rate_check()) {
1466        audit_log_lost("rate limit exceeded");
1467    } else {
1468        struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1469        nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1470
1471        if (audit_pid) {
1472            skb_queue_tail(&audit_skb_queue, ab->skb);
1473            wake_up_interruptible(&kauditd_wait);
1474        } else {
1475            audit_printk_skb(ab->skb);
1476        }
1477        ab->skb = NULL;
1478    }
1479    audit_buffer_free(ab);
1480}
1481
1482/**
1483 * audit_log - Log an audit record
1484 * @ctx: audit context
1485 * @gfp_mask: type of allocation
1486 * @type: audit message type
1487 * @fmt: format string to use
1488 * @...: variable parameters matching the format string
1489 *
1490 * This is a convenience function that calls audit_log_start,
1491 * audit_log_vformat, and audit_log_end. It may be called
1492 * in any context.
1493 */
1494void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1495           const char *fmt, ...)
1496{
1497    struct audit_buffer *ab;
1498    va_list args;
1499
1500    ab = audit_log_start(ctx, gfp_mask, type);
1501    if (ab) {
1502        va_start(args, fmt);
1503        audit_log_vformat(ab, fmt, args);
1504        va_end(args);
1505        audit_log_end(ab);
1506    }
1507}
1508
1509#ifdef CONFIG_SECURITY
1510/**
1511 * audit_log_secctx - Converts and logs SELinux context
1512 * @ab: audit_buffer
1513 * @secid: security number
1514 *
1515 * This is a helper function that calls security_secid_to_secctx to convert
1516 * secid to secctx and then adds the (converted) SELinux context to the audit
1517 * log by calling audit_log_format, thus also preventing leak of internal secid
1518 * to userspace. If secid cannot be converted audit_panic is called.
1519 */
1520void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1521{
1522    u32 len;
1523    char *secctx;
1524
1525    if (security_secid_to_secctx(secid, &secctx, &len)) {
1526        audit_panic("Cannot convert secid to context");
1527    } else {
1528        audit_log_format(ab, " obj=%s", secctx);
1529        security_release_secctx(secctx, len);
1530    }
1531}
1532EXPORT_SYMBOL(audit_log_secctx);
1533#endif
1534
1535EXPORT_SYMBOL(audit_log_start);
1536EXPORT_SYMBOL(audit_log_end);
1537EXPORT_SYMBOL(audit_log_format);
1538EXPORT_SYMBOL(audit_log);
1539

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