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 <asm/atomic.h>
47#include <linux/mm.h>
48#include <linux/module.h>
49#include <linux/slab.h>
50#include <linux/err.h>
51#include <linux/kthread.h>
52
53#include <linux/audit.h>
54
55#include <net/sock.h>
56#include <net/netlink.h>
57#include <linux/skbuff.h>
58#include <linux/netlink.h>
59#include <linux/freezer.h>
60#include <linux/tty.h>
61
62#include "audit.h"
63
64/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
65 * (Initialization happens after skb_init is called.) */
66#define AUDIT_DISABLED -1
67#define AUDIT_UNINITIALIZED 0
68#define AUDIT_INITIALIZED 1
69static int audit_initialized;
70
71#define AUDIT_OFF 0
72#define AUDIT_ON 1
73#define AUDIT_LOCKED 2
74int audit_enabled;
75int audit_ever_enabled;
76
77/* Default state when kernel boots without any parameters. */
78static int audit_default;
79
80/* If auditing cannot proceed, audit_failure selects what happens. */
81static int audit_failure = AUDIT_FAIL_PRINTK;
82
83/*
84 * If audit records are to be written to the netlink socket, audit_pid
85 * contains the pid of the auditd process and audit_nlk_pid contains
86 * the pid to use to send netlink messages to that process.
87 */
88int audit_pid;
89static int audit_nlk_pid;
90
91/* If audit_rate_limit is non-zero, limit the rate of sending audit records
92 * to that number per second. This prevents DoS attacks, but results in
93 * audit records being dropped. */
94static int audit_rate_limit;
95
96/* Number of outstanding audit_buffers allowed. */
97static int audit_backlog_limit = 64;
98static int audit_backlog_wait_time = 60 * HZ;
99static int audit_backlog_wait_overflow = 0;
100
101/* The identity of the user shutting down the audit system. */
102uid_t audit_sig_uid = -1;
103pid_t audit_sig_pid = -1;
104u32 audit_sig_sid = 0;
105
106/* Records can be lost in several ways:
107   0) [suppressed in audit_alloc]
108   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
109   2) out of memory in audit_log_move [alloc_skb]
110   3) suppressed due to audit_rate_limit
111   4) suppressed due to audit_backlog_limit
112*/
113static atomic_t audit_lost = ATOMIC_INIT(0);
114
115/* The netlink socket. */
116static struct sock *audit_sock;
117
118/* Hash for inode-based rules */
119struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
120
121/* The audit_freelist is a list of pre-allocated audit buffers (if more
122 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
123 * being placed on the freelist). */
124static DEFINE_SPINLOCK(audit_freelist_lock);
125static int audit_freelist_count;
126static LIST_HEAD(audit_freelist);
127
128static struct sk_buff_head audit_skb_queue;
129/* queue of skbs to send to auditd when/if it comes back */
130static struct sk_buff_head audit_skb_hold_queue;
131static struct task_struct *kauditd_task;
132static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
133static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
134
135/* Serialize requests from userspace. */
136DEFINE_MUTEX(audit_cmd_mutex);
137
138/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
139 * audit records. Since printk uses a 1024 byte buffer, this buffer
140 * should be at least that large. */
141#define AUDIT_BUFSIZ 1024
142
143/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
144 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
145#define AUDIT_MAXFREE (2*NR_CPUS)
146
147/* The audit_buffer is used when formatting an audit record. The caller
148 * locks briefly to get the record off the freelist or to allocate the
149 * buffer, and locks briefly to send the buffer to the netlink layer or
150 * to place it on a transmit queue. Multiple audit_buffers can be in
151 * use simultaneously. */
152struct audit_buffer {
153    struct list_head list;
154    struct sk_buff *skb; /* formatted skb ready to send */
155    struct audit_context *ctx; /* NULL or associated context */
156    gfp_t gfp_mask;
157};
158
159struct audit_reply {
160    int pid;
161    struct sk_buff *skb;
162};
163
164static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
165{
166    if (ab) {
167        struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
168        nlh->nlmsg_pid = pid;
169    }
170}
171
172void audit_panic(const char *message)
173{
174    switch (audit_failure)
175    {
176    case AUDIT_FAIL_SILENT:
177        break;
178    case AUDIT_FAIL_PRINTK:
179        if (printk_ratelimit())
180            printk(KERN_ERR "audit: %s\n", message);
181        break;
182    case AUDIT_FAIL_PANIC:
183        /* test audit_pid since printk is always losey, why bother? */
184        if (audit_pid)
185            panic("audit: %s\n", message);
186        break;
187    }
188}
189
190static inline int audit_rate_check(void)
191{
192    static unsigned long last_check = 0;
193    static int messages = 0;
194    static DEFINE_SPINLOCK(lock);
195    unsigned long flags;
196    unsigned long now;
197    unsigned long elapsed;
198    int retval = 0;
199
200    if (!audit_rate_limit) return 1;
201
202    spin_lock_irqsave(&lock, flags);
203    if (++messages < audit_rate_limit) {
204        retval = 1;
205    } else {
206        now = jiffies;
207        elapsed = now - last_check;
208        if (elapsed > HZ) {
209            last_check = now;
210            messages = 0;
211            retval = 1;
212        }
213    }
214    spin_unlock_irqrestore(&lock, flags);
215
216    return retval;
217}
218
219/**
220 * audit_log_lost - conditionally log lost audit message event
221 * @message: the message stating reason for lost audit message
222 *
223 * Emit at least 1 message per second, even if audit_rate_check is
224 * throttling.
225 * Always increment the lost messages counter.
226*/
227void audit_log_lost(const char *message)
228{
229    static unsigned long last_msg = 0;
230    static DEFINE_SPINLOCK(lock);
231    unsigned long flags;
232    unsigned long now;
233    int print;
234
235    atomic_inc(&audit_lost);
236
237    print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
238
239    if (!print) {
240        spin_lock_irqsave(&lock, flags);
241        now = jiffies;
242        if (now - last_msg > HZ) {
243            print = 1;
244            last_msg = now;
245        }
246        spin_unlock_irqrestore(&lock, flags);
247    }
248
249    if (print) {
250        if (printk_ratelimit())
251            printk(KERN_WARNING
252                "audit: audit_lost=%d audit_rate_limit=%d "
253                "audit_backlog_limit=%d\n",
254                atomic_read(&audit_lost),
255                audit_rate_limit,
256                audit_backlog_limit);
257        audit_panic(message);
258    }
259}
260
261static int audit_log_config_change(char *function_name, int new, int old,
262                   uid_t loginuid, u32 sessionid, u32 sid,
263                   int allow_changes)
264{
265    struct audit_buffer *ab;
266    int rc = 0;
267
268    ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
269    audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
270             old, loginuid, sessionid);
271    if (sid) {
272        char *ctx = NULL;
273        u32 len;
274
275        rc = security_secid_to_secctx(sid, &ctx, &len);
276        if (rc) {
277            audit_log_format(ab, " sid=%u", sid);
278            allow_changes = 0; /* Something weird, deny request */
279        } else {
280            audit_log_format(ab, " subj=%s", ctx);
281            security_release_secctx(ctx, len);
282        }
283    }
284    audit_log_format(ab, " res=%d", allow_changes);
285    audit_log_end(ab);
286    return rc;
287}
288
289static int audit_do_config_change(char *function_name, int *to_change,
290                  int new, uid_t loginuid, u32 sessionid,
291                  u32 sid)
292{
293    int allow_changes, rc = 0, old = *to_change;
294
295    /* check if we are locked */
296    if (audit_enabled == AUDIT_LOCKED)
297        allow_changes = 0;
298    else
299        allow_changes = 1;
300
301    if (audit_enabled != AUDIT_OFF) {
302        rc = audit_log_config_change(function_name, new, old, loginuid,
303                         sessionid, sid, allow_changes);
304        if (rc)
305            allow_changes = 0;
306    }
307
308    /* If we are allowed, make the change */
309    if (allow_changes == 1)
310        *to_change = new;
311    /* Not allowed, update reason */
312    else if (rc == 0)
313        rc = -EPERM;
314    return rc;
315}
316
317static int audit_set_rate_limit(int limit, uid_t loginuid, u32 sessionid,
318                u32 sid)
319{
320    return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
321                      limit, loginuid, sessionid, sid);
322}
323
324static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
325                   u32 sid)
326{
327    return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
328                      limit, loginuid, sessionid, sid);
329}
330
331static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
332{
333    int rc;
334    if (state < AUDIT_OFF || state > AUDIT_LOCKED)
335        return -EINVAL;
336
337    rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
338                     loginuid, sessionid, sid);
339
340    if (!rc)
341        audit_ever_enabled |= !!state;
342
343    return rc;
344}
345
346static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
347{
348    if (state != AUDIT_FAIL_SILENT
349        && state != AUDIT_FAIL_PRINTK
350        && state != AUDIT_FAIL_PANIC)
351        return -EINVAL;
352
353    return audit_do_config_change("audit_failure", &audit_failure, state,
354                      loginuid, sessionid, sid);
355}
356
357/*
358 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
359 * already have been sent via prink/syslog and so if these messages are dropped
360 * it is not a huge concern since we already passed the audit_log_lost()
361 * notification and stuff. This is just nice to get audit messages during
362 * boot before auditd is running or messages generated while auditd is stopped.
363 * This only holds messages is audit_default is set, aka booting with audit=1
364 * or building your kernel that way.
365 */
366static void audit_hold_skb(struct sk_buff *skb)
367{
368    if (audit_default &&
369        skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
370        skb_queue_tail(&audit_skb_hold_queue, skb);
371    else
372        kfree_skb(skb);
373}
374
375/*
376 * For one reason or another this nlh isn't getting delivered to the userspace
377 * audit daemon, just send it to printk.
378 */
379static void audit_printk_skb(struct sk_buff *skb)
380{
381    struct nlmsghdr *nlh = nlmsg_hdr(skb);
382    char *data = NLMSG_DATA(nlh);
383
384    if (nlh->nlmsg_type != AUDIT_EOE) {
385        if (printk_ratelimit())
386            printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
387        else
388            audit_log_lost("printk limit exceeded\n");
389    }
390
391    audit_hold_skb(skb);
392}
393
394static void kauditd_send_skb(struct sk_buff *skb)
395{
396    int err;
397    /* take a reference in case we can't send it and we want to hold it */
398    skb_get(skb);
399    err = netlink_unicast(audit_sock, skb, audit_nlk_pid, 0);
400    if (err < 0) {
401        BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
402        printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
403        audit_log_lost("auditd dissapeared\n");
404        audit_pid = 0;
405        /* we might get lucky and get this in the next auditd */
406        audit_hold_skb(skb);
407    } else
408        /* drop the extra reference if sent ok */
409        consume_skb(skb);
410}
411
412static int kauditd_thread(void *dummy)
413{
414    struct sk_buff *skb;
415
416    set_freezable();
417    while (!kthread_should_stop()) {
418        /*
419         * if auditd just started drain the queue of messages already
420         * sent to syslog/printk. remember loss here is ok. we already
421         * called audit_log_lost() if it didn't go out normally. so the
422         * race between the skb_dequeue and the next check for audit_pid
423         * doesn't matter.
424         *
425         * if you ever find kauditd to be too slow we can get a perf win
426         * by doing our own locking and keeping better track if there
427         * are messages in this queue. I don't see the need now, but
428         * in 5 years when I want to play with this again I'll see this
429         * note and still have no friggin idea what i'm thinking today.
430         */
431        if (audit_default && audit_pid) {
432            skb = skb_dequeue(&audit_skb_hold_queue);
433            if (unlikely(skb)) {
434                while (skb && audit_pid) {
435                    kauditd_send_skb(skb);
436                    skb = skb_dequeue(&audit_skb_hold_queue);
437                }
438            }
439        }
440
441        skb = skb_dequeue(&audit_skb_queue);
442        wake_up(&audit_backlog_wait);
443        if (skb) {
444            if (audit_pid)
445                kauditd_send_skb(skb);
446            else
447                audit_printk_skb(skb);
448        } else {
449            DECLARE_WAITQUEUE(wait, current);
450            set_current_state(TASK_INTERRUPTIBLE);
451            add_wait_queue(&kauditd_wait, &wait);
452
453            if (!skb_queue_len(&audit_skb_queue)) {
454                try_to_freeze();
455                schedule();
456            }
457
458            __set_current_state(TASK_RUNNING);
459            remove_wait_queue(&kauditd_wait, &wait);
460        }
461    }
462    return 0;
463}
464
465static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
466{
467    struct task_struct *tsk;
468    int err;
469
470    read_lock(&tasklist_lock);
471    tsk = find_task_by_vpid(pid);
472    err = -ESRCH;
473    if (!tsk)
474        goto out;
475    err = 0;
476
477    spin_lock_irq(&tsk->sighand->siglock);
478    if (!tsk->signal->audit_tty)
479        err = -EPERM;
480    spin_unlock_irq(&tsk->sighand->siglock);
481    if (err)
482        goto out;
483
484    tty_audit_push_task(tsk, loginuid, sessionid);
485out:
486    read_unlock(&tasklist_lock);
487    return err;
488}
489
490int audit_send_list(void *_dest)
491{
492    struct audit_netlink_list *dest = _dest;
493    int pid = dest->pid;
494    struct sk_buff *skb;
495
496    /* wait for parent to finish and send an ACK */
497    mutex_lock(&audit_cmd_mutex);
498    mutex_unlock(&audit_cmd_mutex);
499
500    while ((skb = __skb_dequeue(&dest->q)) != NULL)
501        netlink_unicast(audit_sock, skb, pid, 0);
502
503    kfree(dest);
504
505    return 0;
506}
507
508struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
509                 int multi, void *payload, int size)
510{
511    struct sk_buff *skb;
512    struct nlmsghdr *nlh;
513    void *data;
514    int flags = multi ? NLM_F_MULTI : 0;
515    int t = done ? NLMSG_DONE : type;
516
517    skb = nlmsg_new(size, GFP_KERNEL);
518    if (!skb)
519        return NULL;
520
521    nlh = NLMSG_NEW(skb, pid, seq, t, size, flags);
522    data = NLMSG_DATA(nlh);
523    memcpy(data, payload, size);
524    return skb;
525
526nlmsg_failure: /* Used by NLMSG_NEW */
527    if (skb)
528        kfree_skb(skb);
529    return NULL;
530}
531
532static int audit_send_reply_thread(void *arg)
533{
534    struct audit_reply *reply = (struct audit_reply *)arg;
535
536    mutex_lock(&audit_cmd_mutex);
537    mutex_unlock(&audit_cmd_mutex);
538
539    /* Ignore failure. It'll only happen if the sender goes away,
540       because our timeout is set to infinite. */
541    netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
542    kfree(reply);
543    return 0;
544}
545/**
546 * audit_send_reply - send an audit reply message via netlink
547 * @pid: process id to send reply to
548 * @seq: sequence number
549 * @type: audit message type
550 * @done: done (last) flag
551 * @multi: multi-part message flag
552 * @payload: payload data
553 * @size: payload size
554 *
555 * Allocates an skb, builds the netlink message, and sends it to the pid.
556 * No failure notifications.
557 */
558void audit_send_reply(int pid, int seq, int type, int done, int multi,
559              void *payload, int size)
560{
561    struct sk_buff *skb;
562    struct task_struct *tsk;
563    struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
564                        GFP_KERNEL);
565
566    if (!reply)
567        return;
568
569    skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
570    if (!skb)
571        goto out;
572
573    reply->pid = pid;
574    reply->skb = skb;
575
576    tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
577    if (!IS_ERR(tsk))
578        return;
579    kfree_skb(skb);
580out:
581    kfree(reply);
582}
583
584/*
585 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
586 * control messages.
587 */
588static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
589{
590    int err = 0;
591
592    switch (msg_type) {
593    case AUDIT_GET:
594    case AUDIT_LIST:
595    case AUDIT_LIST_RULES:
596    case AUDIT_SET:
597    case AUDIT_ADD:
598    case AUDIT_ADD_RULE:
599    case AUDIT_DEL:
600    case AUDIT_DEL_RULE:
601    case AUDIT_SIGNAL_INFO:
602    case AUDIT_TTY_GET:
603    case AUDIT_TTY_SET:
604    case AUDIT_TRIM:
605    case AUDIT_MAKE_EQUIV:
606        if (security_netlink_recv(skb, CAP_AUDIT_CONTROL))
607            err = -EPERM;
608        break;
609    case AUDIT_USER:
610    case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
611    case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
612        if (security_netlink_recv(skb, CAP_AUDIT_WRITE))
613            err = -EPERM;
614        break;
615    default: /* bad msg */
616        err = -EINVAL;
617    }
618
619    return err;
620}
621
622static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
623                     u32 pid, u32 uid, uid_t auid, u32 ses,
624                     u32 sid)
625{
626    int rc = 0;
627    char *ctx = NULL;
628    u32 len;
629
630    if (!audit_enabled) {
631        *ab = NULL;
632        return rc;
633    }
634
635    *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
636    audit_log_format(*ab, "user pid=%d uid=%u auid=%u ses=%u",
637             pid, uid, auid, ses);
638    if (sid) {
639        rc = security_secid_to_secctx(sid, &ctx, &len);
640        if (rc)
641            audit_log_format(*ab, " ssid=%u", sid);
642        else {
643            audit_log_format(*ab, " subj=%s", ctx);
644            security_release_secctx(ctx, len);
645        }
646    }
647
648    return rc;
649}
650
651static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
652{
653    u32 uid, pid, seq, sid;
654    void *data;
655    struct audit_status *status_get, status_set;
656    int err;
657    struct audit_buffer *ab;
658    u16 msg_type = nlh->nlmsg_type;
659    uid_t loginuid; /* loginuid of sender */
660    u32 sessionid;
661    struct audit_sig_info *sig_data;
662    char *ctx = NULL;
663    u32 len;
664
665    err = audit_netlink_ok(skb, msg_type);
666    if (err)
667        return err;
668
669    /* As soon as there's any sign of userspace auditd,
670     * start kauditd to talk to it */
671    if (!kauditd_task)
672        kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
673    if (IS_ERR(kauditd_task)) {
674        err = PTR_ERR(kauditd_task);
675        kauditd_task = NULL;
676        return err;
677    }
678
679    pid = NETLINK_CREDS(skb)->pid;
680    uid = NETLINK_CREDS(skb)->uid;
681    loginuid = NETLINK_CB(skb).loginuid;
682    sessionid = NETLINK_CB(skb).sessionid;
683    sid = NETLINK_CB(skb).sid;
684    seq = nlh->nlmsg_seq;
685    data = NLMSG_DATA(nlh);
686
687    switch (msg_type) {
688    case AUDIT_GET:
689        status_set.enabled = audit_enabled;
690        status_set.failure = audit_failure;
691        status_set.pid = audit_pid;
692        status_set.rate_limit = audit_rate_limit;
693        status_set.backlog_limit = audit_backlog_limit;
694        status_set.lost = atomic_read(&audit_lost);
695        status_set.backlog = skb_queue_len(&audit_skb_queue);
696        audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
697                 &status_set, sizeof(status_set));
698        break;
699    case AUDIT_SET:
700        if (nlh->nlmsg_len < sizeof(struct audit_status))
701            return -EINVAL;
702        status_get = (struct audit_status *)data;
703        if (status_get->mask & AUDIT_STATUS_ENABLED) {
704            err = audit_set_enabled(status_get->enabled,
705                        loginuid, sessionid, sid);
706            if (err < 0)
707                return err;
708        }
709        if (status_get->mask & AUDIT_STATUS_FAILURE) {
710            err = audit_set_failure(status_get->failure,
711                        loginuid, sessionid, sid);
712            if (err < 0)
713                return err;
714        }
715        if (status_get->mask & AUDIT_STATUS_PID) {
716            int new_pid = status_get->pid;
717
718            if (audit_enabled != AUDIT_OFF)
719                audit_log_config_change("audit_pid", new_pid,
720                            audit_pid, loginuid,
721                            sessionid, sid, 1);
722
723            audit_pid = new_pid;
724            audit_nlk_pid = NETLINK_CB(skb).pid;
725        }
726        if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
727            err = audit_set_rate_limit(status_get->rate_limit,
728                           loginuid, sessionid, sid);
729            if (err < 0)
730                return err;
731        }
732        if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
733            err = audit_set_backlog_limit(status_get->backlog_limit,
734                              loginuid, sessionid, sid);
735        break;
736    case AUDIT_USER:
737    case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
738    case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
739        if (!audit_enabled && msg_type != AUDIT_USER_AVC)
740            return 0;
741
742        err = audit_filter_user(&NETLINK_CB(skb));
743        if (err == 1) {
744            err = 0;
745            if (msg_type == AUDIT_USER_TTY) {
746                err = audit_prepare_user_tty(pid, loginuid,
747                                 sessionid);
748                if (err)
749                    break;
750            }
751            audit_log_common_recv_msg(&ab, msg_type, pid, uid,
752                          loginuid, sessionid, sid);
753
754            if (msg_type != AUDIT_USER_TTY)
755                audit_log_format(ab, " msg='%.1024s'",
756                         (char *)data);
757            else {
758                int size;
759
760                audit_log_format(ab, " msg=");
761                size = nlmsg_len(nlh);
762                if (size > 0 &&
763                    ((unsigned char *)data)[size - 1] == '\0')
764                    size--;
765                audit_log_n_untrustedstring(ab, data, size);
766            }
767            audit_set_pid(ab, pid);
768            audit_log_end(ab);
769        }
770        break;
771    case AUDIT_ADD:
772    case AUDIT_DEL:
773        if (nlmsg_len(nlh) < sizeof(struct audit_rule))
774            return -EINVAL;
775        if (audit_enabled == AUDIT_LOCKED) {
776            audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
777                          uid, loginuid, sessionid, sid);
778
779            audit_log_format(ab, " audit_enabled=%d res=0",
780                     audit_enabled);
781            audit_log_end(ab);
782            return -EPERM;
783        }
784        /* fallthrough */
785    case AUDIT_LIST:
786        err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
787                       uid, seq, data, nlmsg_len(nlh),
788                       loginuid, sessionid, sid);
789        break;
790    case AUDIT_ADD_RULE:
791    case AUDIT_DEL_RULE:
792        if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
793            return -EINVAL;
794        if (audit_enabled == AUDIT_LOCKED) {
795            audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
796                          uid, loginuid, sessionid, sid);
797
798            audit_log_format(ab, " audit_enabled=%d res=0",
799                     audit_enabled);
800            audit_log_end(ab);
801            return -EPERM;
802        }
803        /* fallthrough */
804    case AUDIT_LIST_RULES:
805        err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
806                       uid, seq, data, nlmsg_len(nlh),
807                       loginuid, sessionid, sid);
808        break;
809    case AUDIT_TRIM:
810        audit_trim_trees();
811
812        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
813                      uid, loginuid, sessionid, sid);
814
815        audit_log_format(ab, " op=trim res=1");
816        audit_log_end(ab);
817        break;
818    case AUDIT_MAKE_EQUIV: {
819        void *bufp = data;
820        u32 sizes[2];
821        size_t msglen = nlmsg_len(nlh);
822        char *old, *new;
823
824        err = -EINVAL;
825        if (msglen < 2 * sizeof(u32))
826            break;
827        memcpy(sizes, bufp, 2 * sizeof(u32));
828        bufp += 2 * sizeof(u32);
829        msglen -= 2 * sizeof(u32);
830        old = audit_unpack_string(&bufp, &msglen, sizes[0]);
831        if (IS_ERR(old)) {
832            err = PTR_ERR(old);
833            break;
834        }
835        new = audit_unpack_string(&bufp, &msglen, sizes[1]);
836        if (IS_ERR(new)) {
837            err = PTR_ERR(new);
838            kfree(old);
839            break;
840        }
841        /* OK, here comes... */
842        err = audit_tag_tree(old, new);
843
844        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
845                      uid, loginuid, sessionid, sid);
846
847        audit_log_format(ab, " op=make_equiv old=");
848        audit_log_untrustedstring(ab, old);
849        audit_log_format(ab, " new=");
850        audit_log_untrustedstring(ab, new);
851        audit_log_format(ab, " res=%d", !err);
852        audit_log_end(ab);
853        kfree(old);
854        kfree(new);
855        break;
856    }
857    case AUDIT_SIGNAL_INFO:
858        len = 0;
859        if (audit_sig_sid) {
860            err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
861            if (err)
862                return err;
863        }
864        sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
865        if (!sig_data) {
866            if (audit_sig_sid)
867                security_release_secctx(ctx, len);
868            return -ENOMEM;
869        }
870        sig_data->uid = audit_sig_uid;
871        sig_data->pid = audit_sig_pid;
872        if (audit_sig_sid) {
873            memcpy(sig_data->ctx, ctx, len);
874            security_release_secctx(ctx, len);
875        }
876        audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_SIGNAL_INFO,
877                0, 0, sig_data, sizeof(*sig_data) + len);
878        kfree(sig_data);
879        break;
880    case AUDIT_TTY_GET: {
881        struct audit_tty_status s;
882        struct task_struct *tsk;
883
884        read_lock(&tasklist_lock);
885        tsk = find_task_by_vpid(pid);
886        if (!tsk)
887            err = -ESRCH;
888        else {
889            spin_lock_irq(&tsk->sighand->siglock);
890            s.enabled = tsk->signal->audit_tty != 0;
891            spin_unlock_irq(&tsk->sighand->siglock);
892        }
893        read_unlock(&tasklist_lock);
894        audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_TTY_GET, 0, 0,
895                 &s, sizeof(s));
896        break;
897    }
898    case AUDIT_TTY_SET: {
899        struct audit_tty_status *s;
900        struct task_struct *tsk;
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        read_lock(&tasklist_lock);
908        tsk = find_task_by_vpid(pid);
909        if (!tsk)
910            err = -ESRCH;
911        else {
912            spin_lock_irq(&tsk->sighand->siglock);
913            tsk->signal->audit_tty = s->enabled != 0;
914            spin_unlock_irq(&tsk->sighand->siglock);
915        }
916        read_unlock(&tasklist_lock);
917        break;
918    }
919    default:
920        err = -EINVAL;
921        break;
922    }
923
924    return err < 0 ? err : 0;
925}
926
927/*
928 * Get message from skb. Each message is processed by audit_receive_msg.
929 * Malformed skbs with wrong length are discarded silently.
930 */
931static void audit_receive_skb(struct sk_buff *skb)
932{
933    struct nlmsghdr *nlh;
934    /*
935     * len MUST be signed for NLMSG_NEXT to be able to dec it below 0
936     * if the nlmsg_len was not aligned
937     */
938    int len;
939    int err;
940
941    nlh = nlmsg_hdr(skb);
942    len = skb->len;
943
944    while (NLMSG_OK(nlh, len)) {
945        err = audit_receive_msg(skb, nlh);
946        /* if err or if this message says it wants a response */
947        if (err || (nlh->nlmsg_flags & NLM_F_ACK))
948            netlink_ack(skb, nlh, err);
949
950        nlh = NLMSG_NEXT(nlh, len);
951    }
952}
953
954/* Receive messages from netlink socket. */
955static void audit_receive(struct sk_buff *skb)
956{
957    mutex_lock(&audit_cmd_mutex);
958    audit_receive_skb(skb);
959    mutex_unlock(&audit_cmd_mutex);
960}
961
962/* Initialize audit support at boot time. */
963static int __init audit_init(void)
964{
965    int i;
966
967    if (audit_initialized == AUDIT_DISABLED)
968        return 0;
969
970    printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
971           audit_default ? "enabled" : "disabled");
972    audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, 0,
973                       audit_receive, NULL, THIS_MODULE);
974    if (!audit_sock)
975        audit_panic("cannot initialize netlink socket");
976    else
977        audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
978
979    skb_queue_head_init(&audit_skb_queue);
980    skb_queue_head_init(&audit_skb_hold_queue);
981    audit_initialized = AUDIT_INITIALIZED;
982    audit_enabled = audit_default;
983    audit_ever_enabled |= !!audit_default;
984
985    audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
986
987    for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
988        INIT_LIST_HEAD(&audit_inode_hash[i]);
989
990    return 0;
991}
992__initcall(audit_init);
993
994/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
995static int __init audit_enable(char *str)
996{
997    audit_default = !!simple_strtol(str, NULL, 0);
998    if (!audit_default)
999        audit_initialized = AUDIT_DISABLED;
1000
1001    printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
1002
1003    if (audit_initialized == AUDIT_INITIALIZED) {
1004        audit_enabled = audit_default;
1005        audit_ever_enabled |= !!audit_default;
1006    } else if (audit_initialized == AUDIT_UNINITIALIZED) {
1007        printk(" (after initialization)");
1008    } else {
1009        printk(" (until reboot)");
1010    }
1011    printk("\n");
1012
1013    return 1;
1014}
1015
1016__setup("audit=", audit_enable);
1017
1018static void audit_buffer_free(struct audit_buffer *ab)
1019{
1020    unsigned long flags;
1021
1022    if (!ab)
1023        return;
1024
1025    if (ab->skb)
1026        kfree_skb(ab->skb);
1027
1028    spin_lock_irqsave(&audit_freelist_lock, flags);
1029    if (audit_freelist_count > AUDIT_MAXFREE)
1030        kfree(ab);
1031    else {
1032        audit_freelist_count++;
1033        list_add(&ab->list, &audit_freelist);
1034    }
1035    spin_unlock_irqrestore(&audit_freelist_lock, flags);
1036}
1037
1038static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1039                        gfp_t gfp_mask, int type)
1040{
1041    unsigned long flags;
1042    struct audit_buffer *ab = NULL;
1043    struct nlmsghdr *nlh;
1044
1045    spin_lock_irqsave(&audit_freelist_lock, flags);
1046    if (!list_empty(&audit_freelist)) {
1047        ab = list_entry(audit_freelist.next,
1048                struct audit_buffer, list);
1049        list_del(&ab->list);
1050        --audit_freelist_count;
1051    }
1052    spin_unlock_irqrestore(&audit_freelist_lock, flags);
1053
1054    if (!ab) {
1055        ab = kmalloc(sizeof(*ab), gfp_mask);
1056        if (!ab)
1057            goto err;
1058    }
1059
1060    ab->ctx = ctx;
1061    ab->gfp_mask = gfp_mask;
1062
1063    ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1064    if (!ab->skb)
1065        goto nlmsg_failure;
1066
1067    nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0);
1068
1069    return ab;
1070
1071nlmsg_failure: /* Used by NLMSG_NEW */
1072    kfree_skb(ab->skb);
1073    ab->skb = NULL;
1074err:
1075    audit_buffer_free(ab);
1076    return NULL;
1077}
1078
1079/**
1080 * audit_serial - compute a serial number for the audit record
1081 *
1082 * Compute a serial number for the audit record. Audit records are
1083 * written to user-space as soon as they are generated, so a complete
1084 * audit record may be written in several pieces. The timestamp of the
1085 * record and this serial number are used by the user-space tools to
1086 * determine which pieces belong to the same audit record. The
1087 * (timestamp,serial) tuple is unique for each syscall and is live from
1088 * syscall entry to syscall exit.
1089 *
1090 * NOTE: Another possibility is to store the formatted records off the
1091 * audit context (for those records that have a context), and emit them
1092 * all at syscall exit. However, this could delay the reporting of
1093 * significant errors until syscall exit (or never, if the system
1094 * halts).
1095 */
1096unsigned int audit_serial(void)
1097{
1098    static DEFINE_SPINLOCK(serial_lock);
1099    static unsigned int serial = 0;
1100
1101    unsigned long flags;
1102    unsigned int ret;
1103
1104    spin_lock_irqsave(&serial_lock, flags);
1105    do {
1106        ret = ++serial;
1107    } while (unlikely(!ret));
1108    spin_unlock_irqrestore(&serial_lock, flags);
1109
1110    return ret;
1111}
1112
1113static inline void audit_get_stamp(struct audit_context *ctx,
1114                   struct timespec *t, unsigned int *serial)
1115{
1116    if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1117        *t = CURRENT_TIME;
1118        *serial = audit_serial();
1119    }
1120}
1121
1122/* Obtain an audit buffer. This routine does locking to obtain the
1123 * audit buffer, but then no locking is required for calls to
1124 * audit_log_*format. If the tsk is a task that is currently in a
1125 * syscall, then the syscall is marked as auditable and an audit record
1126 * will be written at syscall exit. If there is no associated task, tsk
1127 * should be NULL. */
1128
1129/**
1130 * audit_log_start - obtain an audit buffer
1131 * @ctx: audit_context (may be NULL)
1132 * @gfp_mask: type of allocation
1133 * @type: audit message type
1134 *
1135 * Returns audit_buffer pointer on success or NULL on error.
1136 *
1137 * Obtain an audit buffer. This routine does locking to obtain the
1138 * audit buffer, but then no locking is required for calls to
1139 * audit_log_*format. If the task (ctx) is a task that is currently in a
1140 * syscall, then the syscall is marked as auditable and an audit record
1141 * will be written at syscall exit. If there is no associated task, then
1142 * task context (ctx) should be NULL.
1143 */
1144struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1145                     int type)
1146{
1147    struct audit_buffer *ab = NULL;
1148    struct timespec t;
1149    unsigned int uninitialized_var(serial);
1150    int reserve;
1151    unsigned long timeout_start = jiffies;
1152
1153    if (audit_initialized != AUDIT_INITIALIZED)
1154        return NULL;
1155
1156    if (unlikely(audit_filter_type(type)))
1157        return NULL;
1158
1159    if (gfp_mask & __GFP_WAIT)
1160        reserve = 0;
1161    else
1162        reserve = 5; /* Allow atomic callers to go up to five
1163                entries over the normal backlog limit */
1164
1165    while (audit_backlog_limit
1166           && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1167        if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
1168            && time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
1169
1170            /* Wait for auditd to drain the queue a little */
1171            DECLARE_WAITQUEUE(wait, current);
1172            set_current_state(TASK_INTERRUPTIBLE);
1173            add_wait_queue(&audit_backlog_wait, &wait);
1174
1175            if (audit_backlog_limit &&
1176                skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1177                schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
1178
1179            __set_current_state(TASK_RUNNING);
1180            remove_wait_queue(&audit_backlog_wait, &wait);
1181            continue;
1182        }
1183        if (audit_rate_check() && printk_ratelimit())
1184            printk(KERN_WARNING
1185                   "audit: audit_backlog=%d > "
1186                   "audit_backlog_limit=%d\n",
1187                   skb_queue_len(&audit_skb_queue),
1188                   audit_backlog_limit);
1189        audit_log_lost("backlog limit exceeded");
1190        audit_backlog_wait_time = audit_backlog_wait_overflow;
1191        wake_up(&audit_backlog_wait);
1192        return NULL;
1193    }
1194
1195    ab = audit_buffer_alloc(ctx, gfp_mask, type);
1196    if (!ab) {
1197        audit_log_lost("out of memory in audit_log_start");
1198        return NULL;
1199    }
1200
1201    audit_get_stamp(ab->ctx, &t, &serial);
1202
1203    audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1204             t.tv_sec, t.tv_nsec/1000000, serial);
1205    return ab;
1206}
1207
1208/**
1209 * audit_expand - expand skb in the audit buffer
1210 * @ab: audit_buffer
1211 * @extra: space to add at tail of the skb
1212 *
1213 * Returns 0 (no space) on failed expansion, or available space if
1214 * successful.
1215 */
1216static inline int audit_expand(struct audit_buffer *ab, int extra)
1217{
1218    struct sk_buff *skb = ab->skb;
1219    int oldtail = skb_tailroom(skb);
1220    int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1221    int newtail = skb_tailroom(skb);
1222
1223    if (ret < 0) {
1224        audit_log_lost("out of memory in audit_expand");
1225        return 0;
1226    }
1227
1228    skb->truesize += newtail - oldtail;
1229    return newtail;
1230}
1231
1232/*
1233 * Format an audit message into the audit buffer. If there isn't enough
1234 * room in the audit buffer, more room will be allocated and vsnprint
1235 * will be called a second time. Currently, we assume that a printk
1236 * can't format message larger than 1024 bytes, so we don't either.
1237 */
1238static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1239                  va_list args)
1240{
1241    int len, avail;
1242    struct sk_buff *skb;
1243    va_list args2;
1244
1245    if (!ab)
1246        return;
1247
1248    BUG_ON(!ab->skb);
1249    skb = ab->skb;
1250    avail = skb_tailroom(skb);
1251    if (avail == 0) {
1252        avail = audit_expand(ab, AUDIT_BUFSIZ);
1253        if (!avail)
1254            goto out;
1255    }
1256    va_copy(args2, args);
1257    len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1258    if (len >= avail) {
1259        /* The printk buffer is 1024 bytes long, so if we get
1260         * here and AUDIT_BUFSIZ is at least 1024, then we can
1261         * log everything that printk could have logged. */
1262        avail = audit_expand(ab,
1263            max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1264        if (!avail)
1265            goto out;
1266        len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1267    }
1268    va_end(args2);
1269    if (len > 0)
1270        skb_put(skb, len);
1271out:
1272    return;
1273}
1274
1275/**
1276 * audit_log_format - format a message into the audit buffer.
1277 * @ab: audit_buffer
1278 * @fmt: format string
1279 * @...: optional parameters matching @fmt string
1280 *
1281 * All the work is done in audit_log_vformat.
1282 */
1283void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1284{
1285    va_list args;
1286
1287    if (!ab)
1288        return;
1289    va_start(args, fmt);
1290    audit_log_vformat(ab, fmt, args);
1291    va_end(args);
1292}
1293
1294/**
1295 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1296 * @ab: the audit_buffer
1297 * @buf: buffer to convert to hex
1298 * @len: length of @buf to be converted
1299 *
1300 * No return value; failure to expand is silently ignored.
1301 *
1302 * This function will take the passed buf and convert it into a string of
1303 * ascii hex digits. The new string is placed onto the skb.
1304 */
1305void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1306        size_t len)
1307{
1308    int i, avail, new_len;
1309    unsigned char *ptr;
1310    struct sk_buff *skb;
1311    static const unsigned char *hex = "0123456789ABCDEF";
1312
1313    if (!ab)
1314        return;
1315
1316    BUG_ON(!ab->skb);
1317    skb = ab->skb;
1318    avail = skb_tailroom(skb);
1319    new_len = len<<1;
1320    if (new_len >= avail) {
1321        /* Round the buffer request up to the next multiple */
1322        new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1323        avail = audit_expand(ab, new_len);
1324        if (!avail)
1325            return;
1326    }
1327
1328    ptr = skb_tail_pointer(skb);
1329    for (i=0; i<len; i++) {
1330        *ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
1331        *ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */
1332    }
1333    *ptr = 0;
1334    skb_put(skb, len << 1); /* new string is twice the old string */
1335}
1336
1337/*
1338 * Format a string of no more than slen characters into the audit buffer,
1339 * enclosed in quote marks.
1340 */
1341void audit_log_n_string(struct audit_buffer *ab, const char *string,
1342            size_t slen)
1343{
1344    int avail, new_len;
1345    unsigned char *ptr;
1346    struct sk_buff *skb;
1347
1348    if (!ab)
1349        return;
1350
1351    BUG_ON(!ab->skb);
1352    skb = ab->skb;
1353    avail = skb_tailroom(skb);
1354    new_len = slen + 3; /* enclosing quotes + null terminator */
1355    if (new_len > avail) {
1356        avail = audit_expand(ab, new_len);
1357        if (!avail)
1358            return;
1359    }
1360    ptr = skb_tail_pointer(skb);
1361    *ptr++ = '"';
1362    memcpy(ptr, string, slen);
1363    ptr += slen;
1364    *ptr++ = '"';
1365    *ptr = 0;
1366    skb_put(skb, slen + 2); /* don't include null terminator */
1367}
1368
1369/**
1370 * audit_string_contains_control - does a string need to be logged in hex
1371 * @string: string to be checked
1372 * @len: max length of the string to check
1373 */
1374int audit_string_contains_control(const char *string, size_t len)
1375{
1376    const unsigned char *p;
1377    for (p = string; p < (const unsigned char *)string + len; p++) {
1378        if (*p == '"' || *p < 0x21 || *p > 0x7e)
1379            return 1;
1380    }
1381    return 0;
1382}
1383
1384/**
1385 * audit_log_n_untrustedstring - log a string that may contain random characters
1386 * @ab: audit_buffer
1387 * @len: length of string (not including trailing null)
1388 * @string: string to be logged
1389 *
1390 * This code will escape a string that is passed to it if the string
1391 * contains a control character, unprintable character, double quote mark,
1392 * or a space. Unescaped strings will start and end with a double quote mark.
1393 * Strings that are escaped are printed in hex (2 digits per char).
1394 *
1395 * The caller specifies the number of characters in the string to log, which may
1396 * or may not be the entire string.
1397 */
1398void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1399                 size_t len)
1400{
1401    if (audit_string_contains_control(string, len))
1402        audit_log_n_hex(ab, string, len);
1403    else
1404        audit_log_n_string(ab, string, len);
1405}
1406
1407/**
1408 * audit_log_untrustedstring - log a string that may contain random characters
1409 * @ab: audit_buffer
1410 * @string: string to be logged
1411 *
1412 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1413 * determine string length.
1414 */
1415void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1416{
1417    audit_log_n_untrustedstring(ab, string, strlen(string));
1418}
1419
1420/* This is a helper-function to print the escaped d_path */
1421void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1422              struct path *path)
1423{
1424    char *p, *pathname;
1425
1426    if (prefix)
1427        audit_log_format(ab, " %s", prefix);
1428
1429    /* We will allow 11 spaces for ' (deleted)' to be appended */
1430    pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1431    if (!pathname) {
1432        audit_log_string(ab, "<no_memory>");
1433        return;
1434    }
1435    p = d_path(path, pathname, PATH_MAX+11);
1436    if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1437        /* FIXME: can we save some information here? */
1438        audit_log_string(ab, "<too_long>");
1439    } else
1440        audit_log_untrustedstring(ab, p);
1441    kfree(pathname);
1442}
1443
1444void audit_log_key(struct audit_buffer *ab, char *key)
1445{
1446    audit_log_format(ab, " key=");
1447    if (key)
1448        audit_log_untrustedstring(ab, key);
1449    else
1450        audit_log_format(ab, "(null)");
1451}
1452
1453/**
1454 * audit_log_end - end one audit record
1455 * @ab: the audit_buffer
1456 *
1457 * The netlink_* functions cannot be called inside an irq context, so
1458 * the audit buffer is placed on a queue and a tasklet is scheduled to
1459 * remove them from the queue outside the irq context. May be called in
1460 * any context.
1461 */
1462void audit_log_end(struct audit_buffer *ab)
1463{
1464    if (!ab)
1465        return;
1466    if (!audit_rate_check()) {
1467        audit_log_lost("rate limit exceeded");
1468    } else {
1469        struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1470        nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
1471
1472        if (audit_pid) {
1473            skb_queue_tail(&audit_skb_queue, ab->skb);
1474            wake_up_interruptible(&kauditd_wait);
1475        } else {
1476            audit_printk_skb(ab->skb);
1477        }
1478        ab->skb = NULL;
1479    }
1480    audit_buffer_free(ab);
1481}
1482
1483/**
1484 * audit_log - Log an audit record
1485 * @ctx: audit context
1486 * @gfp_mask: type of allocation
1487 * @type: audit message type
1488 * @fmt: format string to use
1489 * @...: variable parameters matching the format string
1490 *
1491 * This is a convenience function that calls audit_log_start,
1492 * audit_log_vformat, and audit_log_end. It may be called
1493 * in any context.
1494 */
1495void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1496           const char *fmt, ...)
1497{
1498    struct audit_buffer *ab;
1499    va_list args;
1500
1501    ab = audit_log_start(ctx, gfp_mask, type);
1502    if (ab) {
1503        va_start(args, fmt);
1504        audit_log_vformat(ab, fmt, args);
1505        va_end(args);
1506        audit_log_end(ab);
1507    }
1508}
1509
1510EXPORT_SYMBOL(audit_log_start);
1511EXPORT_SYMBOL(audit_log_end);
1512EXPORT_SYMBOL(audit_log_format);
1513EXPORT_SYMBOL(audit_log);
1514

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