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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
45
46#include <linux/init.h>
47#include <asm/types.h>
48#include <linux/atomic.h>
49#include <linux/mm.h>
50#include <linux/export.h>
51#include <linux/slab.h>
52#include <linux/err.h>
53#include <linux/kthread.h>
54#include <linux/kernel.h>
55#include <linux/syscalls.h>
56
57#include <linux/audit.h>
58
59#include <net/sock.h>
60#include <net/netlink.h>
61#include <linux/skbuff.h>
62#ifdef CONFIG_SECURITY
63#include <linux/security.h>
64#endif
65#include <linux/freezer.h>
66#include <linux/tty.h>
67#include <linux/pid_namespace.h>
68#include <net/netns/generic.h>
69
70#include "audit.h"
71
72/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
73 * (Initialization happens after skb_init is called.) */
74#define AUDIT_DISABLED -1
75#define AUDIT_UNINITIALIZED 0
76#define AUDIT_INITIALIZED 1
77static int audit_initialized;
78
79#define AUDIT_OFF 0
80#define AUDIT_ON 1
81#define AUDIT_LOCKED 2
82u32 audit_enabled;
83u32 audit_ever_enabled;
84
85EXPORT_SYMBOL_GPL(audit_enabled);
86
87/* Default state when kernel boots without any parameters. */
88static u32 audit_default;
89
90/* If auditing cannot proceed, audit_failure selects what happens. */
91static u32 audit_failure = AUDIT_FAIL_PRINTK;
92
93/*
94 * If audit records are to be written to the netlink socket, audit_pid
95 * contains the pid of the auditd process and audit_nlk_portid contains
96 * the portid to use to send netlink messages to that process.
97 */
98int audit_pid;
99static __u32 audit_nlk_portid;
100
101/* If audit_rate_limit is non-zero, limit the rate of sending audit records
102 * to that number per second. This prevents DoS attacks, but results in
103 * audit records being dropped. */
104static u32 audit_rate_limit;
105
106/* Number of outstanding audit_buffers allowed.
107 * When set to zero, this means unlimited. */
108static u32 audit_backlog_limit = 64;
109#define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
110static u32 audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
111static u32 audit_backlog_wait_overflow = 0;
112
113/* The identity of the user shutting down the audit system. */
114kuid_t audit_sig_uid = INVALID_UID;
115pid_t audit_sig_pid = -1;
116u32 audit_sig_sid = 0;
117
118/* Records can be lost in several ways:
119   0) [suppressed in audit_alloc]
120   1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
121   2) out of memory in audit_log_move [alloc_skb]
122   3) suppressed due to audit_rate_limit
123   4) suppressed due to audit_backlog_limit
124*/
125static atomic_t audit_lost = ATOMIC_INIT(0);
126
127/* The netlink socket. */
128static struct sock *audit_sock;
129int audit_net_id;
130
131/* Hash for inode-based rules */
132struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
133
134/* The audit_freelist is a list of pre-allocated audit buffers (if more
135 * than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
136 * being placed on the freelist). */
137static DEFINE_SPINLOCK(audit_freelist_lock);
138static int audit_freelist_count;
139static LIST_HEAD(audit_freelist);
140
141static struct sk_buff_head audit_skb_queue;
142/* queue of skbs to send to auditd when/if it comes back */
143static struct sk_buff_head audit_skb_hold_queue;
144static struct task_struct *kauditd_task;
145static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
146static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
147
148static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
149                   .mask = -1,
150                   .features = 0,
151                   .lock = 0,};
152
153static char *audit_feature_names[2] = {
154    "only_unset_loginuid",
155    "loginuid_immutable",
156};
157
158
159/* Serialize requests from userspace. */
160DEFINE_MUTEX(audit_cmd_mutex);
161
162/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
163 * audit records. Since printk uses a 1024 byte buffer, this buffer
164 * should be at least that large. */
165#define AUDIT_BUFSIZ 1024
166
167/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
168 * audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
169#define AUDIT_MAXFREE (2*NR_CPUS)
170
171/* The audit_buffer is used when formatting an audit record. The caller
172 * locks briefly to get the record off the freelist or to allocate the
173 * buffer, and locks briefly to send the buffer to the netlink layer or
174 * to place it on a transmit queue. Multiple audit_buffers can be in
175 * use simultaneously. */
176struct audit_buffer {
177    struct list_head list;
178    struct sk_buff *skb; /* formatted skb ready to send */
179    struct audit_context *ctx; /* NULL or associated context */
180    gfp_t gfp_mask;
181};
182
183struct audit_reply {
184    __u32 portid;
185    struct net *net;
186    struct sk_buff *skb;
187};
188
189static void audit_set_portid(struct audit_buffer *ab, __u32 portid)
190{
191    if (ab) {
192        struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
193        nlh->nlmsg_pid = portid;
194    }
195}
196
197void audit_panic(const char *message)
198{
199    switch (audit_failure) {
200    case AUDIT_FAIL_SILENT:
201        break;
202    case AUDIT_FAIL_PRINTK:
203        if (printk_ratelimit())
204            pr_err("%s\n", message);
205        break;
206    case AUDIT_FAIL_PANIC:
207        /* test audit_pid since printk is always losey, why bother? */
208        if (audit_pid)
209            panic("audit: %s\n", message);
210        break;
211    }
212}
213
214static inline int audit_rate_check(void)
215{
216    static unsigned long last_check = 0;
217    static int messages = 0;
218    static DEFINE_SPINLOCK(lock);
219    unsigned long flags;
220    unsigned long now;
221    unsigned long elapsed;
222    int retval = 0;
223
224    if (!audit_rate_limit) return 1;
225
226    spin_lock_irqsave(&lock, flags);
227    if (++messages < audit_rate_limit) {
228        retval = 1;
229    } else {
230        now = jiffies;
231        elapsed = now - last_check;
232        if (elapsed > HZ) {
233            last_check = now;
234            messages = 0;
235            retval = 1;
236        }
237    }
238    spin_unlock_irqrestore(&lock, flags);
239
240    return retval;
241}
242
243/**
244 * audit_log_lost - conditionally log lost audit message event
245 * @message: the message stating reason for lost audit message
246 *
247 * Emit at least 1 message per second, even if audit_rate_check is
248 * throttling.
249 * Always increment the lost messages counter.
250*/
251void audit_log_lost(const char *message)
252{
253    static unsigned long last_msg = 0;
254    static DEFINE_SPINLOCK(lock);
255    unsigned long flags;
256    unsigned long now;
257    int print;
258
259    atomic_inc(&audit_lost);
260
261    print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
262
263    if (!print) {
264        spin_lock_irqsave(&lock, flags);
265        now = jiffies;
266        if (now - last_msg > HZ) {
267            print = 1;
268            last_msg = now;
269        }
270        spin_unlock_irqrestore(&lock, flags);
271    }
272
273    if (print) {
274        if (printk_ratelimit())
275            pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
276                atomic_read(&audit_lost),
277                audit_rate_limit,
278                audit_backlog_limit);
279        audit_panic(message);
280    }
281}
282
283static int audit_log_config_change(char *function_name, u32 new, u32 old,
284                   int allow_changes)
285{
286    struct audit_buffer *ab;
287    int rc = 0;
288
289    ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
290    if (unlikely(!ab))
291        return rc;
292    audit_log_format(ab, "%s=%u old=%u", function_name, new, old);
293    audit_log_session_info(ab);
294    rc = audit_log_task_context(ab);
295    if (rc)
296        allow_changes = 0; /* Something weird, deny request */
297    audit_log_format(ab, " res=%d", allow_changes);
298    audit_log_end(ab);
299    return rc;
300}
301
302static int audit_do_config_change(char *function_name, u32 *to_change, u32 new)
303{
304    int allow_changes, rc = 0;
305    u32 old = *to_change;
306
307    /* check if we are locked */
308    if (audit_enabled == AUDIT_LOCKED)
309        allow_changes = 0;
310    else
311        allow_changes = 1;
312
313    if (audit_enabled != AUDIT_OFF) {
314        rc = audit_log_config_change(function_name, new, old, allow_changes);
315        if (rc)
316            allow_changes = 0;
317    }
318
319    /* If we are allowed, make the change */
320    if (allow_changes == 1)
321        *to_change = new;
322    /* Not allowed, update reason */
323    else if (rc == 0)
324        rc = -EPERM;
325    return rc;
326}
327
328static int audit_set_rate_limit(u32 limit)
329{
330    return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
331}
332
333static int audit_set_backlog_limit(u32 limit)
334{
335    return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
336}
337
338static int audit_set_backlog_wait_time(u32 timeout)
339{
340    return audit_do_config_change("audit_backlog_wait_time",
341                      &audit_backlog_wait_time, timeout);
342}
343
344static int audit_set_enabled(u32 state)
345{
346    int rc;
347    if (state < AUDIT_OFF || state > AUDIT_LOCKED)
348        return -EINVAL;
349
350    rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
351    if (!rc)
352        audit_ever_enabled |= !!state;
353
354    return rc;
355}
356
357static int audit_set_failure(u32 state)
358{
359    if (state != AUDIT_FAIL_SILENT
360        && state != AUDIT_FAIL_PRINTK
361        && state != AUDIT_FAIL_PANIC)
362        return -EINVAL;
363
364    return audit_do_config_change("audit_failure", &audit_failure, state);
365}
366
367/*
368 * Queue skbs to be sent to auditd when/if it comes back. These skbs should
369 * already have been sent via prink/syslog and so if these messages are dropped
370 * it is not a huge concern since we already passed the audit_log_lost()
371 * notification and stuff. This is just nice to get audit messages during
372 * boot before auditd is running or messages generated while auditd is stopped.
373 * This only holds messages is audit_default is set, aka booting with audit=1
374 * or building your kernel that way.
375 */
376static void audit_hold_skb(struct sk_buff *skb)
377{
378    if (audit_default &&
379        (!audit_backlog_limit ||
380         skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit))
381        skb_queue_tail(&audit_skb_hold_queue, skb);
382    else
383        kfree_skb(skb);
384}
385
386/*
387 * For one reason or another this nlh isn't getting delivered to the userspace
388 * audit daemon, just send it to printk.
389 */
390static void audit_printk_skb(struct sk_buff *skb)
391{
392    struct nlmsghdr *nlh = nlmsg_hdr(skb);
393    char *data = nlmsg_data(nlh);
394
395    if (nlh->nlmsg_type != AUDIT_EOE) {
396        if (printk_ratelimit())
397            pr_notice("type=%d %s\n", nlh->nlmsg_type, data);
398        else
399            audit_log_lost("printk limit exceeded");
400    }
401
402    audit_hold_skb(skb);
403}
404
405static void kauditd_send_skb(struct sk_buff *skb)
406{
407    int err;
408    /* take a reference in case we can't send it and we want to hold it */
409    skb_get(skb);
410    err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
411    if (err < 0) {
412        BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
413        if (audit_pid) {
414            pr_err("*NO* daemon at audit_pid=%d\n", audit_pid);
415            audit_log_lost("auditd disappeared");
416            audit_pid = 0;
417            audit_sock = NULL;
418        }
419        /* we might get lucky and get this in the next auditd */
420        audit_hold_skb(skb);
421    } else
422        /* drop the extra reference if sent ok */
423        consume_skb(skb);
424}
425
426/*
427 * flush_hold_queue - empty the hold queue if auditd appears
428 *
429 * If auditd just started, drain the queue of messages already
430 * sent to syslog/printk. Remember loss here is ok. We already
431 * called audit_log_lost() if it didn't go out normally. so the
432 * race between the skb_dequeue and the next check for audit_pid
433 * doesn't matter.
434 *
435 * If you ever find kauditd to be too slow we can get a perf win
436 * by doing our own locking and keeping better track if there
437 * are messages in this queue. I don't see the need now, but
438 * in 5 years when I want to play with this again I'll see this
439 * note and still have no friggin idea what i'm thinking today.
440 */
441static void flush_hold_queue(void)
442{
443    struct sk_buff *skb;
444
445    if (!audit_default || !audit_pid)
446        return;
447
448    skb = skb_dequeue(&audit_skb_hold_queue);
449    if (likely(!skb))
450        return;
451
452    while (skb && audit_pid) {
453        kauditd_send_skb(skb);
454        skb = skb_dequeue(&audit_skb_hold_queue);
455    }
456
457    /*
458     * if auditd just disappeared but we
459     * dequeued an skb we need to drop ref
460     */
461    if (skb)
462        consume_skb(skb);
463}
464
465static int kauditd_thread(void *dummy)
466{
467    set_freezable();
468    while (!kthread_should_stop()) {
469        struct sk_buff *skb;
470        DECLARE_WAITQUEUE(wait, current);
471
472        flush_hold_queue();
473
474        skb = skb_dequeue(&audit_skb_queue);
475
476        if (skb) {
477            if (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit)
478                wake_up(&audit_backlog_wait);
479            if (audit_pid)
480                kauditd_send_skb(skb);
481            else
482                audit_printk_skb(skb);
483            continue;
484        }
485        set_current_state(TASK_INTERRUPTIBLE);
486        add_wait_queue(&kauditd_wait, &wait);
487
488        if (!skb_queue_len(&audit_skb_queue)) {
489            try_to_freeze();
490            schedule();
491        }
492
493        __set_current_state(TASK_RUNNING);
494        remove_wait_queue(&kauditd_wait, &wait);
495    }
496    return 0;
497}
498
499int audit_send_list(void *_dest)
500{
501    struct audit_netlink_list *dest = _dest;
502    struct sk_buff *skb;
503    struct net *net = dest->net;
504    struct audit_net *aunet = net_generic(net, audit_net_id);
505
506    /* wait for parent to finish and send an ACK */
507    mutex_lock(&audit_cmd_mutex);
508    mutex_unlock(&audit_cmd_mutex);
509
510    while ((skb = __skb_dequeue(&dest->q)) != NULL)
511        netlink_unicast(aunet->nlsk, skb, dest->portid, 0);
512
513    put_net(net);
514    kfree(dest);
515
516    return 0;
517}
518
519struct sk_buff *audit_make_reply(__u32 portid, int seq, int type, int done,
520                 int multi, const void *payload, int size)
521{
522    struct sk_buff *skb;
523    struct nlmsghdr *nlh;
524    void *data;
525    int flags = multi ? NLM_F_MULTI : 0;
526    int t = done ? NLMSG_DONE : type;
527
528    skb = nlmsg_new(size, GFP_KERNEL);
529    if (!skb)
530        return NULL;
531
532    nlh = nlmsg_put(skb, portid, seq, t, size, flags);
533    if (!nlh)
534        goto out_kfree_skb;
535    data = nlmsg_data(nlh);
536    memcpy(data, payload, size);
537    return skb;
538
539out_kfree_skb:
540    kfree_skb(skb);
541    return NULL;
542}
543
544static int audit_send_reply_thread(void *arg)
545{
546    struct audit_reply *reply = (struct audit_reply *)arg;
547    struct net *net = reply->net;
548    struct audit_net *aunet = net_generic(net, audit_net_id);
549
550    mutex_lock(&audit_cmd_mutex);
551    mutex_unlock(&audit_cmd_mutex);
552
553    /* Ignore failure. It'll only happen if the sender goes away,
554       because our timeout is set to infinite. */
555    netlink_unicast(aunet->nlsk , reply->skb, reply->portid, 0);
556    put_net(net);
557    kfree(reply);
558    return 0;
559}
560/**
561 * audit_send_reply - send an audit reply message via netlink
562 * @request_skb: skb of request we are replying to (used to target the reply)
563 * @seq: sequence number
564 * @type: audit message type
565 * @done: done (last) flag
566 * @multi: multi-part message flag
567 * @payload: payload data
568 * @size: payload size
569 *
570 * Allocates an skb, builds the netlink message, and sends it to the port id.
571 * No failure notifications.
572 */
573static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
574                 int multi, const void *payload, int size)
575{
576    u32 portid = NETLINK_CB(request_skb).portid;
577    struct net *net = sock_net(NETLINK_CB(request_skb).sk);
578    struct sk_buff *skb;
579    struct task_struct *tsk;
580    struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
581                        GFP_KERNEL);
582
583    if (!reply)
584        return;
585
586    skb = audit_make_reply(portid, seq, type, done, multi, payload, size);
587    if (!skb)
588        goto out;
589
590    reply->net = get_net(net);
591    reply->portid = portid;
592    reply->skb = skb;
593
594    tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
595    if (!IS_ERR(tsk))
596        return;
597    kfree_skb(skb);
598out:
599    kfree(reply);
600}
601
602/*
603 * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
604 * control messages.
605 */
606static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
607{
608    int err = 0;
609
610    /* Only support initial user namespace for now. */
611    /*
612     * We return ECONNREFUSED because it tricks userspace into thinking
613     * that audit was not configured into the kernel. Lots of users
614     * configure their PAM stack (because that's what the distro does)
615     * to reject login if unable to send messages to audit. If we return
616     * ECONNREFUSED the PAM stack thinks the kernel does not have audit
617     * configured in and will let login proceed. If we return EPERM
618     * userspace will reject all logins. This should be removed when we
619     * support non init namespaces!!
620     */
621    if (current_user_ns() != &init_user_ns)
622        return -ECONNREFUSED;
623
624    switch (msg_type) {
625    case AUDIT_LIST:
626    case AUDIT_ADD:
627    case AUDIT_DEL:
628        return -EOPNOTSUPP;
629    case AUDIT_GET:
630    case AUDIT_SET:
631    case AUDIT_GET_FEATURE:
632    case AUDIT_SET_FEATURE:
633    case AUDIT_LIST_RULES:
634    case AUDIT_ADD_RULE:
635    case AUDIT_DEL_RULE:
636    case AUDIT_SIGNAL_INFO:
637    case AUDIT_TTY_GET:
638    case AUDIT_TTY_SET:
639    case AUDIT_TRIM:
640    case AUDIT_MAKE_EQUIV:
641        /* Only support auditd and auditctl in initial pid namespace
642         * for now. */
643        if ((task_active_pid_ns(current) != &init_pid_ns))
644            return -EPERM;
645
646        if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
647            err = -EPERM;
648        break;
649    case AUDIT_USER:
650    case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
651    case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
652        if (!netlink_capable(skb, CAP_AUDIT_WRITE))
653            err = -EPERM;
654        break;
655    default: /* bad msg */
656        err = -EINVAL;
657    }
658
659    return err;
660}
661
662static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
663{
664    int rc = 0;
665    uid_t uid = from_kuid(&init_user_ns, current_uid());
666    pid_t pid = task_tgid_nr(current);
667
668    if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
669        *ab = NULL;
670        return rc;
671    }
672
673    *ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
674    if (unlikely(!*ab))
675        return rc;
676    audit_log_format(*ab, "pid=%d uid=%u", pid, uid);
677    audit_log_session_info(*ab);
678    audit_log_task_context(*ab);
679
680    return rc;
681}
682
683int is_audit_feature_set(int i)
684{
685    return af.features & AUDIT_FEATURE_TO_MASK(i);
686}
687
688
689static int audit_get_feature(struct sk_buff *skb)
690{
691    u32 seq;
692
693    seq = nlmsg_hdr(skb)->nlmsg_seq;
694
695    audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &af, sizeof(af));
696
697    return 0;
698}
699
700static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
701                     u32 old_lock, u32 new_lock, int res)
702{
703    struct audit_buffer *ab;
704
705    if (audit_enabled == AUDIT_OFF)
706        return;
707
708    ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
709    audit_log_task_info(ab, current);
710    audit_log_format(ab, "feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
711             audit_feature_names[which], !!old_feature, !!new_feature,
712             !!old_lock, !!new_lock, res);
713    audit_log_end(ab);
714}
715
716static int audit_set_feature(struct sk_buff *skb)
717{
718    struct audit_features *uaf;
719    int i;
720
721    BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > sizeof(audit_feature_names)/sizeof(audit_feature_names[0]));
722    uaf = nlmsg_data(nlmsg_hdr(skb));
723
724    /* if there is ever a version 2 we should handle that here */
725
726    for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
727        u32 feature = AUDIT_FEATURE_TO_MASK(i);
728        u32 old_feature, new_feature, old_lock, new_lock;
729
730        /* if we are not changing this feature, move along */
731        if (!(feature & uaf->mask))
732            continue;
733
734        old_feature = af.features & feature;
735        new_feature = uaf->features & feature;
736        new_lock = (uaf->lock | af.lock) & feature;
737        old_lock = af.lock & feature;
738
739        /* are we changing a locked feature? */
740        if (old_lock && (new_feature != old_feature)) {
741            audit_log_feature_change(i, old_feature, new_feature,
742                         old_lock, new_lock, 0);
743            return -EPERM;
744        }
745    }
746    /* nothing invalid, do the changes */
747    for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
748        u32 feature = AUDIT_FEATURE_TO_MASK(i);
749        u32 old_feature, new_feature, old_lock, new_lock;
750
751        /* if we are not changing this feature, move along */
752        if (!(feature & uaf->mask))
753            continue;
754
755        old_feature = af.features & feature;
756        new_feature = uaf->features & feature;
757        old_lock = af.lock & feature;
758        new_lock = (uaf->lock | af.lock) & feature;
759
760        if (new_feature != old_feature)
761            audit_log_feature_change(i, old_feature, new_feature,
762                         old_lock, new_lock, 1);
763
764        if (new_feature)
765            af.features |= feature;
766        else
767            af.features &= ~feature;
768        af.lock |= new_lock;
769    }
770
771    return 0;
772}
773
774static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
775{
776    u32 seq;
777    void *data;
778    int err;
779    struct audit_buffer *ab;
780    u16 msg_type = nlh->nlmsg_type;
781    struct audit_sig_info *sig_data;
782    char *ctx = NULL;
783    u32 len;
784
785    err = audit_netlink_ok(skb, msg_type);
786    if (err)
787        return err;
788
789    /* As soon as there's any sign of userspace auditd,
790     * start kauditd to talk to it */
791    if (!kauditd_task) {
792        kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
793        if (IS_ERR(kauditd_task)) {
794            err = PTR_ERR(kauditd_task);
795            kauditd_task = NULL;
796            return err;
797        }
798    }
799    seq = nlh->nlmsg_seq;
800    data = nlmsg_data(nlh);
801
802    switch (msg_type) {
803    case AUDIT_GET: {
804        struct audit_status s;
805        memset(&s, 0, sizeof(s));
806        s.enabled = audit_enabled;
807        s.failure = audit_failure;
808        s.pid = audit_pid;
809        s.rate_limit = audit_rate_limit;
810        s.backlog_limit = audit_backlog_limit;
811        s.lost = atomic_read(&audit_lost);
812        s.backlog = skb_queue_len(&audit_skb_queue);
813        s.version = AUDIT_VERSION_LATEST;
814        s.backlog_wait_time = audit_backlog_wait_time;
815        audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
816        break;
817    }
818    case AUDIT_SET: {
819        struct audit_status s;
820        memset(&s, 0, sizeof(s));
821        /* guard against past and future API changes */
822        memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
823        if (s.mask & AUDIT_STATUS_ENABLED) {
824            err = audit_set_enabled(s.enabled);
825            if (err < 0)
826                return err;
827        }
828        if (s.mask & AUDIT_STATUS_FAILURE) {
829            err = audit_set_failure(s.failure);
830            if (err < 0)
831                return err;
832        }
833        if (s.mask & AUDIT_STATUS_PID) {
834            int new_pid = s.pid;
835
836            if ((!new_pid) && (task_tgid_vnr(current) != audit_pid))
837                return -EACCES;
838            if (audit_enabled != AUDIT_OFF)
839                audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
840            audit_pid = new_pid;
841            audit_nlk_portid = NETLINK_CB(skb).portid;
842            audit_sock = skb->sk;
843        }
844        if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
845            err = audit_set_rate_limit(s.rate_limit);
846            if (err < 0)
847                return err;
848        }
849        if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
850            err = audit_set_backlog_limit(s.backlog_limit);
851            if (err < 0)
852                return err;
853        }
854        if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
855            if (sizeof(s) > (size_t)nlh->nlmsg_len)
856                return -EINVAL;
857            if (s.backlog_wait_time < 0 ||
858                s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
859                return -EINVAL;
860            err = audit_set_backlog_wait_time(s.backlog_wait_time);
861            if (err < 0)
862                return err;
863        }
864        break;
865    }
866    case AUDIT_GET_FEATURE:
867        err = audit_get_feature(skb);
868        if (err)
869            return err;
870        break;
871    case AUDIT_SET_FEATURE:
872        err = audit_set_feature(skb);
873        if (err)
874            return err;
875        break;
876    case AUDIT_USER:
877    case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
878    case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
879        if (!audit_enabled && msg_type != AUDIT_USER_AVC)
880            return 0;
881
882        err = audit_filter_user(msg_type);
883        if (err == 1) { /* match or error */
884            err = 0;
885            if (msg_type == AUDIT_USER_TTY) {
886                err = tty_audit_push_current();
887                if (err)
888                    break;
889            }
890            mutex_unlock(&audit_cmd_mutex);
891            audit_log_common_recv_msg(&ab, msg_type);
892            if (msg_type != AUDIT_USER_TTY)
893                audit_log_format(ab, " msg='%.*s'",
894                         AUDIT_MESSAGE_TEXT_MAX,
895                         (char *)data);
896            else {
897                int size;
898
899                audit_log_format(ab, " data=");
900                size = nlmsg_len(nlh);
901                if (size > 0 &&
902                    ((unsigned char *)data)[size - 1] == '\0')
903                    size--;
904                audit_log_n_untrustedstring(ab, data, size);
905            }
906            audit_set_portid(ab, NETLINK_CB(skb).portid);
907            audit_log_end(ab);
908            mutex_lock(&audit_cmd_mutex);
909        }
910        break;
911    case AUDIT_ADD_RULE:
912    case AUDIT_DEL_RULE:
913        if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
914            return -EINVAL;
915        if (audit_enabled == AUDIT_LOCKED) {
916            audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
917            audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
918            audit_log_end(ab);
919            return -EPERM;
920        }
921        err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
922                       seq, data, nlmsg_len(nlh));
923        break;
924    case AUDIT_LIST_RULES:
925        err = audit_list_rules_send(skb, seq);
926        break;
927    case AUDIT_TRIM:
928        audit_trim_trees();
929        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
930        audit_log_format(ab, " op=trim res=1");
931        audit_log_end(ab);
932        break;
933    case AUDIT_MAKE_EQUIV: {
934        void *bufp = data;
935        u32 sizes[2];
936        size_t msglen = nlmsg_len(nlh);
937        char *old, *new;
938
939        err = -EINVAL;
940        if (msglen < 2 * sizeof(u32))
941            break;
942        memcpy(sizes, bufp, 2 * sizeof(u32));
943        bufp += 2 * sizeof(u32);
944        msglen -= 2 * sizeof(u32);
945        old = audit_unpack_string(&bufp, &msglen, sizes[0]);
946        if (IS_ERR(old)) {
947            err = PTR_ERR(old);
948            break;
949        }
950        new = audit_unpack_string(&bufp, &msglen, sizes[1]);
951        if (IS_ERR(new)) {
952            err = PTR_ERR(new);
953            kfree(old);
954            break;
955        }
956        /* OK, here comes... */
957        err = audit_tag_tree(old, new);
958
959        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
960
961        audit_log_format(ab, " op=make_equiv old=");
962        audit_log_untrustedstring(ab, old);
963        audit_log_format(ab, " new=");
964        audit_log_untrustedstring(ab, new);
965        audit_log_format(ab, " res=%d", !err);
966        audit_log_end(ab);
967        kfree(old);
968        kfree(new);
969        break;
970    }
971    case AUDIT_SIGNAL_INFO:
972        len = 0;
973        if (audit_sig_sid) {
974            err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
975            if (err)
976                return err;
977        }
978        sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
979        if (!sig_data) {
980            if (audit_sig_sid)
981                security_release_secctx(ctx, len);
982            return -ENOMEM;
983        }
984        sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
985        sig_data->pid = audit_sig_pid;
986        if (audit_sig_sid) {
987            memcpy(sig_data->ctx, ctx, len);
988            security_release_secctx(ctx, len);
989        }
990        audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
991                 sig_data, sizeof(*sig_data) + len);
992        kfree(sig_data);
993        break;
994    case AUDIT_TTY_GET: {
995        struct audit_tty_status s;
996        struct task_struct *tsk = current;
997
998        spin_lock(&tsk->sighand->siglock);
999        s.enabled = tsk->signal->audit_tty;
1000        s.log_passwd = tsk->signal->audit_tty_log_passwd;
1001        spin_unlock(&tsk->sighand->siglock);
1002
1003        audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
1004        break;
1005    }
1006    case AUDIT_TTY_SET: {
1007        struct audit_tty_status s, old;
1008        struct task_struct *tsk = current;
1009        struct audit_buffer *ab;
1010
1011        memset(&s, 0, sizeof(s));
1012        /* guard against past and future API changes */
1013        memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
1014        /* check if new data is valid */
1015        if ((s.enabled != 0 && s.enabled != 1) ||
1016            (s.log_passwd != 0 && s.log_passwd != 1))
1017            err = -EINVAL;
1018
1019        spin_lock(&tsk->sighand->siglock);
1020        old.enabled = tsk->signal->audit_tty;
1021        old.log_passwd = tsk->signal->audit_tty_log_passwd;
1022        if (!err) {
1023            tsk->signal->audit_tty = s.enabled;
1024            tsk->signal->audit_tty_log_passwd = s.log_passwd;
1025        }
1026        spin_unlock(&tsk->sighand->siglock);
1027
1028        audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
1029        audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
1030                 " old-log_passwd=%d new-log_passwd=%d res=%d",
1031                 old.enabled, s.enabled, old.log_passwd,
1032                 s.log_passwd, !err);
1033        audit_log_end(ab);
1034        break;
1035    }
1036    default:
1037        err = -EINVAL;
1038        break;
1039    }
1040
1041    return err < 0 ? err : 0;
1042}
1043
1044/*
1045 * Get message from skb. Each message is processed by audit_receive_msg.
1046 * Malformed skbs with wrong length are discarded silently.
1047 */
1048static void audit_receive_skb(struct sk_buff *skb)
1049{
1050    struct nlmsghdr *nlh;
1051    /*
1052     * len MUST be signed for nlmsg_next to be able to dec it below 0
1053     * if the nlmsg_len was not aligned
1054     */
1055    int len;
1056    int err;
1057
1058    nlh = nlmsg_hdr(skb);
1059    len = skb->len;
1060
1061    while (nlmsg_ok(nlh, len)) {
1062        err = audit_receive_msg(skb, nlh);
1063        /* if err or if this message says it wants a response */
1064        if (err || (nlh->nlmsg_flags & NLM_F_ACK))
1065            netlink_ack(skb, nlh, err);
1066
1067        nlh = nlmsg_next(nlh, &len);
1068    }
1069}
1070
1071/* Receive messages from netlink socket. */
1072static void audit_receive(struct sk_buff *skb)
1073{
1074    mutex_lock(&audit_cmd_mutex);
1075    audit_receive_skb(skb);
1076    mutex_unlock(&audit_cmd_mutex);
1077}
1078
1079static int __net_init audit_net_init(struct net *net)
1080{
1081    struct netlink_kernel_cfg cfg = {
1082        .input = audit_receive,
1083    };
1084
1085    struct audit_net *aunet = net_generic(net, audit_net_id);
1086
1087    aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
1088    if (aunet->nlsk == NULL) {
1089        audit_panic("cannot initialize netlink socket in namespace");
1090        return -ENOMEM;
1091    }
1092    aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
1093    return 0;
1094}
1095
1096static void __net_exit audit_net_exit(struct net *net)
1097{
1098    struct audit_net *aunet = net_generic(net, audit_net_id);
1099    struct sock *sock = aunet->nlsk;
1100    if (sock == audit_sock) {
1101        audit_pid = 0;
1102        audit_sock = NULL;
1103    }
1104
1105    RCU_INIT_POINTER(aunet->nlsk, NULL);
1106    synchronize_net();
1107    netlink_kernel_release(sock);
1108}
1109
1110static struct pernet_operations audit_net_ops __net_initdata = {
1111    .init = audit_net_init,
1112    .exit = audit_net_exit,
1113    .id = &audit_net_id,
1114    .size = sizeof(struct audit_net),
1115};
1116
1117/* Initialize audit support at boot time. */
1118static int __init audit_init(void)
1119{
1120    int i;
1121
1122    if (audit_initialized == AUDIT_DISABLED)
1123        return 0;
1124
1125    pr_info("initializing netlink subsys (%s)\n",
1126        audit_default ? "enabled" : "disabled");
1127    register_pernet_subsys(&audit_net_ops);
1128
1129    skb_queue_head_init(&audit_skb_queue);
1130    skb_queue_head_init(&audit_skb_hold_queue);
1131    audit_initialized = AUDIT_INITIALIZED;
1132    audit_enabled = audit_default;
1133    audit_ever_enabled |= !!audit_default;
1134
1135    audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
1136
1137    for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
1138        INIT_LIST_HEAD(&audit_inode_hash[i]);
1139
1140    return 0;
1141}
1142__initcall(audit_init);
1143
1144/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
1145static int __init audit_enable(char *str)
1146{
1147    audit_default = !!simple_strtol(str, NULL, 0);
1148    if (!audit_default)
1149        audit_initialized = AUDIT_DISABLED;
1150
1151    pr_info("%s\n", audit_default ?
1152        "enabled (after initialization)" : "disabled (until reboot)");
1153
1154    return 1;
1155}
1156__setup("audit=", audit_enable);
1157
1158/* Process kernel command-line parameter at boot time.
1159 * audit_backlog_limit=<n> */
1160static int __init audit_backlog_limit_set(char *str)
1161{
1162    u32 audit_backlog_limit_arg;
1163
1164    pr_info("audit_backlog_limit: ");
1165    if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
1166        pr_cont("using default of %u, unable to parse %s\n",
1167            audit_backlog_limit, str);
1168        return 1;
1169    }
1170
1171    audit_backlog_limit = audit_backlog_limit_arg;
1172    pr_cont("%d\n", audit_backlog_limit);
1173
1174    return 1;
1175}
1176__setup("audit_backlog_limit=", audit_backlog_limit_set);
1177
1178static void audit_buffer_free(struct audit_buffer *ab)
1179{
1180    unsigned long flags;
1181
1182    if (!ab)
1183        return;
1184
1185    if (ab->skb)
1186        kfree_skb(ab->skb);
1187
1188    spin_lock_irqsave(&audit_freelist_lock, flags);
1189    if (audit_freelist_count > AUDIT_MAXFREE)
1190        kfree(ab);
1191    else {
1192        audit_freelist_count++;
1193        list_add(&ab->list, &audit_freelist);
1194    }
1195    spin_unlock_irqrestore(&audit_freelist_lock, flags);
1196}
1197
1198static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
1199                        gfp_t gfp_mask, int type)
1200{
1201    unsigned long flags;
1202    struct audit_buffer *ab = NULL;
1203    struct nlmsghdr *nlh;
1204
1205    spin_lock_irqsave(&audit_freelist_lock, flags);
1206    if (!list_empty(&audit_freelist)) {
1207        ab = list_entry(audit_freelist.next,
1208                struct audit_buffer, list);
1209        list_del(&ab->list);
1210        --audit_freelist_count;
1211    }
1212    spin_unlock_irqrestore(&audit_freelist_lock, flags);
1213
1214    if (!ab) {
1215        ab = kmalloc(sizeof(*ab), gfp_mask);
1216        if (!ab)
1217            goto err;
1218    }
1219
1220    ab->ctx = ctx;
1221    ab->gfp_mask = gfp_mask;
1222
1223    ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);
1224    if (!ab->skb)
1225        goto err;
1226
1227    nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
1228    if (!nlh)
1229        goto out_kfree_skb;
1230
1231    return ab;
1232
1233out_kfree_skb:
1234    kfree_skb(ab->skb);
1235    ab->skb = NULL;
1236err:
1237    audit_buffer_free(ab);
1238    return NULL;
1239}
1240
1241/**
1242 * audit_serial - compute a serial number for the audit record
1243 *
1244 * Compute a serial number for the audit record. Audit records are
1245 * written to user-space as soon as they are generated, so a complete
1246 * audit record may be written in several pieces. The timestamp of the
1247 * record and this serial number are used by the user-space tools to
1248 * determine which pieces belong to the same audit record. The
1249 * (timestamp,serial) tuple is unique for each syscall and is live from
1250 * syscall entry to syscall exit.
1251 *
1252 * NOTE: Another possibility is to store the formatted records off the
1253 * audit context (for those records that have a context), and emit them
1254 * all at syscall exit. However, this could delay the reporting of
1255 * significant errors until syscall exit (or never, if the system
1256 * halts).
1257 */
1258unsigned int audit_serial(void)
1259{
1260    static DEFINE_SPINLOCK(serial_lock);
1261    static unsigned int serial = 0;
1262
1263    unsigned long flags;
1264    unsigned int ret;
1265
1266    spin_lock_irqsave(&serial_lock, flags);
1267    do {
1268        ret = ++serial;
1269    } while (unlikely(!ret));
1270    spin_unlock_irqrestore(&serial_lock, flags);
1271
1272    return ret;
1273}
1274
1275static inline void audit_get_stamp(struct audit_context *ctx,
1276                   struct timespec *t, unsigned int *serial)
1277{
1278    if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
1279        *t = CURRENT_TIME;
1280        *serial = audit_serial();
1281    }
1282}
1283
1284/*
1285 * Wait for auditd to drain the queue a little
1286 */
1287static long wait_for_auditd(long sleep_time)
1288{
1289    DECLARE_WAITQUEUE(wait, current);
1290    set_current_state(TASK_UNINTERRUPTIBLE);
1291    add_wait_queue_exclusive(&audit_backlog_wait, &wait);
1292
1293    if (audit_backlog_limit &&
1294        skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
1295        sleep_time = schedule_timeout(sleep_time);
1296
1297    __set_current_state(TASK_RUNNING);
1298    remove_wait_queue(&audit_backlog_wait, &wait);
1299
1300    return sleep_time;
1301}
1302
1303/**
1304 * audit_log_start - obtain an audit buffer
1305 * @ctx: audit_context (may be NULL)
1306 * @gfp_mask: type of allocation
1307 * @type: audit message type
1308 *
1309 * Returns audit_buffer pointer on success or NULL on error.
1310 *
1311 * Obtain an audit buffer. This routine does locking to obtain the
1312 * audit buffer, but then no locking is required for calls to
1313 * audit_log_*format. If the task (ctx) is a task that is currently in a
1314 * syscall, then the syscall is marked as auditable and an audit record
1315 * will be written at syscall exit. If there is no associated task, then
1316 * task context (ctx) should be NULL.
1317 */
1318struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
1319                     int type)
1320{
1321    struct audit_buffer *ab = NULL;
1322    struct timespec t;
1323    unsigned int uninitialized_var(serial);
1324    int reserve = 5; /* Allow atomic callers to go up to five
1325                entries over the normal backlog limit */
1326    unsigned long timeout_start = jiffies;
1327
1328    if (audit_initialized != AUDIT_INITIALIZED)
1329        return NULL;
1330
1331    if (unlikely(audit_filter_type(type)))
1332        return NULL;
1333
1334    if (gfp_mask & __GFP_WAIT) {
1335        if (audit_pid && audit_pid == current->pid)
1336            gfp_mask &= ~__GFP_WAIT;
1337        else
1338            reserve = 0;
1339    }
1340
1341    while (audit_backlog_limit
1342           && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
1343        if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
1344            long sleep_time;
1345
1346            sleep_time = timeout_start + audit_backlog_wait_time - jiffies;
1347            if (sleep_time > 0) {
1348                sleep_time = wait_for_auditd(sleep_time);
1349                if (sleep_time > 0)
1350                    continue;
1351            }
1352        }
1353        if (audit_rate_check() && printk_ratelimit())
1354            pr_warn("audit_backlog=%d > audit_backlog_limit=%d\n",
1355                skb_queue_len(&audit_skb_queue),
1356                audit_backlog_limit);
1357        audit_log_lost("backlog limit exceeded");
1358        audit_backlog_wait_time = audit_backlog_wait_overflow;
1359        wake_up(&audit_backlog_wait);
1360        return NULL;
1361    }
1362
1363    audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
1364
1365    ab = audit_buffer_alloc(ctx, gfp_mask, type);
1366    if (!ab) {
1367        audit_log_lost("out of memory in audit_log_start");
1368        return NULL;
1369    }
1370
1371    audit_get_stamp(ab->ctx, &t, &serial);
1372
1373    audit_log_format(ab, "audit(%lu.%03lu:%u): ",
1374             t.tv_sec, t.tv_nsec/1000000, serial);
1375    return ab;
1376}
1377
1378/**
1379 * audit_expand - expand skb in the audit buffer
1380 * @ab: audit_buffer
1381 * @extra: space to add at tail of the skb
1382 *
1383 * Returns 0 (no space) on failed expansion, or available space if
1384 * successful.
1385 */
1386static inline int audit_expand(struct audit_buffer *ab, int extra)
1387{
1388    struct sk_buff *skb = ab->skb;
1389    int oldtail = skb_tailroom(skb);
1390    int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
1391    int newtail = skb_tailroom(skb);
1392
1393    if (ret < 0) {
1394        audit_log_lost("out of memory in audit_expand");
1395        return 0;
1396    }
1397
1398    skb->truesize += newtail - oldtail;
1399    return newtail;
1400}
1401
1402/*
1403 * Format an audit message into the audit buffer. If there isn't enough
1404 * room in the audit buffer, more room will be allocated and vsnprint
1405 * will be called a second time. Currently, we assume that a printk
1406 * can't format message larger than 1024 bytes, so we don't either.
1407 */
1408static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
1409                  va_list args)
1410{
1411    int len, avail;
1412    struct sk_buff *skb;
1413    va_list args2;
1414
1415    if (!ab)
1416        return;
1417
1418    BUG_ON(!ab->skb);
1419    skb = ab->skb;
1420    avail = skb_tailroom(skb);
1421    if (avail == 0) {
1422        avail = audit_expand(ab, AUDIT_BUFSIZ);
1423        if (!avail)
1424            goto out;
1425    }
1426    va_copy(args2, args);
1427    len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
1428    if (len >= avail) {
1429        /* The printk buffer is 1024 bytes long, so if we get
1430         * here and AUDIT_BUFSIZ is at least 1024, then we can
1431         * log everything that printk could have logged. */
1432        avail = audit_expand(ab,
1433            max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
1434        if (!avail)
1435            goto out_va_end;
1436        len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
1437    }
1438    if (len > 0)
1439        skb_put(skb, len);
1440out_va_end:
1441    va_end(args2);
1442out:
1443    return;
1444}
1445
1446/**
1447 * audit_log_format - format a message into the audit buffer.
1448 * @ab: audit_buffer
1449 * @fmt: format string
1450 * @...: optional parameters matching @fmt string
1451 *
1452 * All the work is done in audit_log_vformat.
1453 */
1454void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
1455{
1456    va_list args;
1457
1458    if (!ab)
1459        return;
1460    va_start(args, fmt);
1461    audit_log_vformat(ab, fmt, args);
1462    va_end(args);
1463}
1464
1465/**
1466 * audit_log_hex - convert a buffer to hex and append it to the audit skb
1467 * @ab: the audit_buffer
1468 * @buf: buffer to convert to hex
1469 * @len: length of @buf to be converted
1470 *
1471 * No return value; failure to expand is silently ignored.
1472 *
1473 * This function will take the passed buf and convert it into a string of
1474 * ascii hex digits. The new string is placed onto the skb.
1475 */
1476void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
1477        size_t len)
1478{
1479    int i, avail, new_len;
1480    unsigned char *ptr;
1481    struct sk_buff *skb;
1482
1483    if (!ab)
1484        return;
1485
1486    BUG_ON(!ab->skb);
1487    skb = ab->skb;
1488    avail = skb_tailroom(skb);
1489    new_len = len<<1;
1490    if (new_len >= avail) {
1491        /* Round the buffer request up to the next multiple */
1492        new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
1493        avail = audit_expand(ab, new_len);
1494        if (!avail)
1495            return;
1496    }
1497
1498    ptr = skb_tail_pointer(skb);
1499    for (i = 0; i < len; i++)
1500        ptr = hex_byte_pack_upper(ptr, buf[i]);
1501    *ptr = 0;
1502    skb_put(skb, len << 1); /* new string is twice the old string */
1503}
1504
1505/*
1506 * Format a string of no more than slen characters into the audit buffer,
1507 * enclosed in quote marks.
1508 */
1509void audit_log_n_string(struct audit_buffer *ab, const char *string,
1510            size_t slen)
1511{
1512    int avail, new_len;
1513    unsigned char *ptr;
1514    struct sk_buff *skb;
1515
1516    if (!ab)
1517        return;
1518
1519    BUG_ON(!ab->skb);
1520    skb = ab->skb;
1521    avail = skb_tailroom(skb);
1522    new_len = slen + 3; /* enclosing quotes + null terminator */
1523    if (new_len > avail) {
1524        avail = audit_expand(ab, new_len);
1525        if (!avail)
1526            return;
1527    }
1528    ptr = skb_tail_pointer(skb);
1529    *ptr++ = '"';
1530    memcpy(ptr, string, slen);
1531    ptr += slen;
1532    *ptr++ = '"';
1533    *ptr = 0;
1534    skb_put(skb, slen + 2); /* don't include null terminator */
1535}
1536
1537/**
1538 * audit_string_contains_control - does a string need to be logged in hex
1539 * @string: string to be checked
1540 * @len: max length of the string to check
1541 */
1542int audit_string_contains_control(const char *string, size_t len)
1543{
1544    const unsigned char *p;
1545    for (p = string; p < (const unsigned char *)string + len; p++) {
1546        if (*p == '"' || *p < 0x21 || *p > 0x7e)
1547            return 1;
1548    }
1549    return 0;
1550}
1551
1552/**
1553 * audit_log_n_untrustedstring - log a string that may contain random characters
1554 * @ab: audit_buffer
1555 * @len: length of string (not including trailing null)
1556 * @string: string to be logged
1557 *
1558 * This code will escape a string that is passed to it if the string
1559 * contains a control character, unprintable character, double quote mark,
1560 * or a space. Unescaped strings will start and end with a double quote mark.
1561 * Strings that are escaped are printed in hex (2 digits per char).
1562 *
1563 * The caller specifies the number of characters in the string to log, which may
1564 * or may not be the entire string.
1565 */
1566void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
1567                 size_t len)
1568{
1569    if (audit_string_contains_control(string, len))
1570        audit_log_n_hex(ab, string, len);
1571    else
1572        audit_log_n_string(ab, string, len);
1573}
1574
1575/**
1576 * audit_log_untrustedstring - log a string that may contain random characters
1577 * @ab: audit_buffer
1578 * @string: string to be logged
1579 *
1580 * Same as audit_log_n_untrustedstring(), except that strlen is used to
1581 * determine string length.
1582 */
1583void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
1584{
1585    audit_log_n_untrustedstring(ab, string, strlen(string));
1586}
1587
1588/* This is a helper-function to print the escaped d_path */
1589void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
1590              const struct path *path)
1591{
1592    char *p, *pathname;
1593
1594    if (prefix)
1595        audit_log_format(ab, "%s", prefix);
1596
1597    /* We will allow 11 spaces for ' (deleted)' to be appended */
1598    pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
1599    if (!pathname) {
1600        audit_log_string(ab, "<no_memory>");
1601        return;
1602    }
1603    p = d_path(path, pathname, PATH_MAX+11);
1604    if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
1605        /* FIXME: can we save some information here? */
1606        audit_log_string(ab, "<too_long>");
1607    } else
1608        audit_log_untrustedstring(ab, p);
1609    kfree(pathname);
1610}
1611
1612void audit_log_session_info(struct audit_buffer *ab)
1613{
1614    unsigned int sessionid = audit_get_sessionid(current);
1615    uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1616
1617    audit_log_format(ab, " auid=%u ses=%u", auid, sessionid);
1618}
1619
1620void audit_log_key(struct audit_buffer *ab, char *key)
1621{
1622    audit_log_format(ab, " key=");
1623    if (key)
1624        audit_log_untrustedstring(ab, key);
1625    else
1626        audit_log_format(ab, "(null)");
1627}
1628
1629void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
1630{
1631    int i;
1632
1633    audit_log_format(ab, " %s=", prefix);
1634    CAP_FOR_EACH_U32(i) {
1635        audit_log_format(ab, "%08x",
1636                 cap->cap[(_KERNEL_CAPABILITY_U32S-1) - i]);
1637    }
1638}
1639
1640void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
1641{
1642    kernel_cap_t *perm = &name->fcap.permitted;
1643    kernel_cap_t *inh = &name->fcap.inheritable;
1644    int log = 0;
1645
1646    if (!cap_isclear(*perm)) {
1647        audit_log_cap(ab, "cap_fp", perm);
1648        log = 1;
1649    }
1650    if (!cap_isclear(*inh)) {
1651        audit_log_cap(ab, "cap_fi", inh);
1652        log = 1;
1653    }
1654
1655    if (log)
1656        audit_log_format(ab, " cap_fe=%d cap_fver=%x",
1657                 name->fcap.fE, name->fcap_ver);
1658}
1659
1660static inline int audit_copy_fcaps(struct audit_names *name,
1661                   const struct dentry *dentry)
1662{
1663    struct cpu_vfs_cap_data caps;
1664    int rc;
1665
1666    if (!dentry)
1667        return 0;
1668
1669    rc = get_vfs_caps_from_disk(dentry, &caps);
1670    if (rc)
1671        return rc;
1672
1673    name->fcap.permitted = caps.permitted;
1674    name->fcap.inheritable = caps.inheritable;
1675    name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
1676    name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
1677                VFS_CAP_REVISION_SHIFT;
1678
1679    return 0;
1680}
1681
1682/* Copy inode data into an audit_names. */
1683void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
1684              const struct inode *inode)
1685{
1686    name->ino = inode->i_ino;
1687    name->dev = inode->i_sb->s_dev;
1688    name->mode = inode->i_mode;
1689    name->uid = inode->i_uid;
1690    name->gid = inode->i_gid;
1691    name->rdev = inode->i_rdev;
1692    security_inode_getsecid(inode, &name->osid);
1693    audit_copy_fcaps(name, dentry);
1694}
1695
1696/**
1697 * audit_log_name - produce AUDIT_PATH record from struct audit_names
1698 * @context: audit_context for the task
1699 * @n: audit_names structure with reportable details
1700 * @path: optional path to report instead of audit_names->name
1701 * @record_num: record number to report when handling a list of names
1702 * @call_panic: optional pointer to int that will be updated if secid fails
1703 */
1704void audit_log_name(struct audit_context *context, struct audit_names *n,
1705            struct path *path, int record_num, int *call_panic)
1706{
1707    struct audit_buffer *ab;
1708    ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
1709    if (!ab)
1710        return;
1711
1712    audit_log_format(ab, "item=%d", record_num);
1713
1714    if (path)
1715        audit_log_d_path(ab, " name=", path);
1716    else if (n->name) {
1717        switch (n->name_len) {
1718        case AUDIT_NAME_FULL:
1719            /* log the full path */
1720            audit_log_format(ab, " name=");
1721            audit_log_untrustedstring(ab, n->name->name);
1722            break;
1723        case 0:
1724            /* name was specified as a relative path and the
1725             * directory component is the cwd */
1726            audit_log_d_path(ab, " name=", &context->pwd);
1727            break;
1728        default:
1729            /* log the name's directory component */
1730            audit_log_format(ab, " name=");
1731            audit_log_n_untrustedstring(ab, n->name->name,
1732                            n->name_len);
1733        }
1734    } else
1735        audit_log_format(ab, " name=(null)");
1736
1737    if (n->ino != (unsigned long)-1) {
1738        audit_log_format(ab, " inode=%lu"
1739                 " dev=%02x:%02x mode=%#ho"
1740                 " ouid=%u ogid=%u rdev=%02x:%02x",
1741                 n->ino,
1742                 MAJOR(n->dev),
1743                 MINOR(n->dev),
1744                 n->mode,
1745                 from_kuid(&init_user_ns, n->uid),
1746                 from_kgid(&init_user_ns, n->gid),
1747                 MAJOR(n->rdev),
1748                 MINOR(n->rdev));
1749    }
1750    if (n->osid != 0) {
1751        char *ctx = NULL;
1752        u32 len;
1753        if (security_secid_to_secctx(
1754            n->osid, &ctx, &len)) {
1755            audit_log_format(ab, " osid=%u", n->osid);
1756            if (call_panic)
1757                *call_panic = 2;
1758        } else {
1759            audit_log_format(ab, " obj=%s", ctx);
1760            security_release_secctx(ctx, len);
1761        }
1762    }
1763
1764    /* log the audit_names record type */
1765    audit_log_format(ab, " nametype=");
1766    switch(n->type) {
1767    case AUDIT_TYPE_NORMAL:
1768        audit_log_format(ab, "NORMAL");
1769        break;
1770    case AUDIT_TYPE_PARENT:
1771        audit_log_format(ab, "PARENT");
1772        break;
1773    case AUDIT_TYPE_CHILD_DELETE:
1774        audit_log_format(ab, "DELETE");
1775        break;
1776    case AUDIT_TYPE_CHILD_CREATE:
1777        audit_log_format(ab, "CREATE");
1778        break;
1779    default:
1780        audit_log_format(ab, "UNKNOWN");
1781        break;
1782    }
1783
1784    audit_log_fcaps(ab, n);
1785    audit_log_end(ab);
1786}
1787
1788int audit_log_task_context(struct audit_buffer *ab)
1789{
1790    char *ctx = NULL;
1791    unsigned len;
1792    int error;
1793    u32 sid;
1794
1795    security_task_getsecid(current, &sid);
1796    if (!sid)
1797        return 0;
1798
1799    error = security_secid_to_secctx(sid, &ctx, &len);
1800    if (error) {
1801        if (error != -EINVAL)
1802            goto error_path;
1803        return 0;
1804    }
1805
1806    audit_log_format(ab, " subj=%s", ctx);
1807    security_release_secctx(ctx, len);
1808    return 0;
1809
1810error_path:
1811    audit_panic("error in audit_log_task_context");
1812    return error;
1813}
1814EXPORT_SYMBOL(audit_log_task_context);
1815
1816void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
1817{
1818    const struct cred *cred;
1819    char name[sizeof(tsk->comm)];
1820    struct mm_struct *mm = tsk->mm;
1821    char *tty;
1822
1823    if (!ab)
1824        return;
1825
1826    /* tsk == current */
1827    cred = current_cred();
1828
1829    spin_lock_irq(&tsk->sighand->siglock);
1830    if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
1831        tty = tsk->signal->tty->name;
1832    else
1833        tty = "(none)";
1834    spin_unlock_irq(&tsk->sighand->siglock);
1835
1836    audit_log_format(ab,
1837             " ppid=%d pid=%d auid=%u uid=%u gid=%u"
1838             " euid=%u suid=%u fsuid=%u"
1839             " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
1840             task_ppid_nr(tsk),
1841             task_pid_nr(tsk),
1842             from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
1843             from_kuid(&init_user_ns, cred->uid),
1844             from_kgid(&init_user_ns, cred->gid),
1845             from_kuid(&init_user_ns, cred->euid),
1846             from_kuid(&init_user_ns, cred->suid),
1847             from_kuid(&init_user_ns, cred->fsuid),
1848             from_kgid(&init_user_ns, cred->egid),
1849             from_kgid(&init_user_ns, cred->sgid),
1850             from_kgid(&init_user_ns, cred->fsgid),
1851             tty, audit_get_sessionid(tsk));
1852
1853    get_task_comm(name, tsk);
1854    audit_log_format(ab, " comm=");
1855    audit_log_untrustedstring(ab, name);
1856
1857    if (mm) {
1858        down_read(&mm->mmap_sem);
1859        if (mm->exe_file)
1860            audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
1861        up_read(&mm->mmap_sem);
1862    } else
1863        audit_log_format(ab, " exe=(null)");
1864    audit_log_task_context(ab);
1865}
1866EXPORT_SYMBOL(audit_log_task_info);
1867
1868/**
1869 * audit_log_link_denied - report a link restriction denial
1870 * @operation: specific link opreation
1871 * @link: the path that triggered the restriction
1872 */
1873void audit_log_link_denied(const char *operation, struct path *link)
1874{
1875    struct audit_buffer *ab;
1876    struct audit_names *name;
1877
1878    name = kzalloc(sizeof(*name), GFP_NOFS);
1879    if (!name)
1880        return;
1881
1882    /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */
1883    ab = audit_log_start(current->audit_context, GFP_KERNEL,
1884                 AUDIT_ANOM_LINK);
1885    if (!ab)
1886        goto out;
1887    audit_log_format(ab, "op=%s", operation);
1888    audit_log_task_info(ab, current);
1889    audit_log_format(ab, " res=0");
1890    audit_log_end(ab);
1891
1892    /* Generate AUDIT_PATH record with object. */
1893    name->type = AUDIT_TYPE_NORMAL;
1894    audit_copy_inode(name, link->dentry, link->dentry->d_inode);
1895    audit_log_name(current->audit_context, name, link, 0, NULL);
1896out:
1897    kfree(name);
1898}
1899
1900/**
1901 * audit_log_end - end one audit record
1902 * @ab: the audit_buffer
1903 *
1904 * The netlink_* functions cannot be called inside an irq context, so
1905 * the audit buffer is placed on a queue and a tasklet is scheduled to
1906 * remove them from the queue outside the irq context. May be called in
1907 * any context.
1908 */
1909void audit_log_end(struct audit_buffer *ab)
1910{
1911    if (!ab)
1912        return;
1913    if (!audit_rate_check()) {
1914        audit_log_lost("rate limit exceeded");
1915    } else {
1916        struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
1917        nlh->nlmsg_len = ab->skb->len - NLMSG_HDRLEN;
1918
1919        if (audit_pid) {
1920            skb_queue_tail(&audit_skb_queue, ab->skb);
1921            wake_up_interruptible(&kauditd_wait);
1922        } else {
1923            audit_printk_skb(ab->skb);
1924        }
1925        ab->skb = NULL;
1926    }
1927    audit_buffer_free(ab);
1928}
1929
1930/**
1931 * audit_log - Log an audit record
1932 * @ctx: audit context
1933 * @gfp_mask: type of allocation
1934 * @type: audit message type
1935 * @fmt: format string to use
1936 * @...: variable parameters matching the format string
1937 *
1938 * This is a convenience function that calls audit_log_start,
1939 * audit_log_vformat, and audit_log_end. It may be called
1940 * in any context.
1941 */
1942void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
1943           const char *fmt, ...)
1944{
1945    struct audit_buffer *ab;
1946    va_list args;
1947
1948    ab = audit_log_start(ctx, gfp_mask, type);
1949    if (ab) {
1950        va_start(args, fmt);
1951        audit_log_vformat(ab, fmt, args);
1952        va_end(args);
1953        audit_log_end(ab);
1954    }
1955}
1956
1957#ifdef CONFIG_SECURITY
1958/**
1959 * audit_log_secctx - Converts and logs SELinux context
1960 * @ab: audit_buffer
1961 * @secid: security number
1962 *
1963 * This is a helper function that calls security_secid_to_secctx to convert
1964 * secid to secctx and then adds the (converted) SELinux context to the audit
1965 * log by calling audit_log_format, thus also preventing leak of internal secid
1966 * to userspace. If secid cannot be converted audit_panic is called.
1967 */
1968void audit_log_secctx(struct audit_buffer *ab, u32 secid)
1969{
1970    u32 len;
1971    char *secctx;
1972
1973    if (security_secid_to_secctx(secid, &secctx, &len)) {
1974        audit_panic("Cannot convert secid to context");
1975    } else {
1976        audit_log_format(ab, " obj=%s", secctx);
1977        security_release_secctx(secctx, len);
1978    }
1979}
1980EXPORT_SYMBOL(audit_log_secctx);
1981#endif
1982
1983EXPORT_SYMBOL(audit_log_start);
1984EXPORT_SYMBOL(audit_log_end);
1985EXPORT_SYMBOL(audit_log_format);
1986EXPORT_SYMBOL(audit_log);
1987

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