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audit.c
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/* audit.c -- Auditing support
* Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
* System-call specific features have moved to auditsc.c
*
* Copyright 2003-2007 Red Hat Inc., Durham, North Carolina.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Written by Rickard E. (Rik) Faith <faith@redhat.com>
*
* Goals: 1) Integrate fully with Security Modules.
* 2) Minimal run-time overhead:
* a) Minimal when syscall auditing is disabled (audit_enable=0).
* b) Small when syscall auditing is enabled and no audit record
* is generated (defer as much work as possible to record
* generation time):
* i) context is allocated,
* ii) names from getname are stored without a copy, and
* iii) inode information stored from path_lookup.
* 3) Ability to disable syscall auditing at boot time (audit=0).
* 4) Usable by other parts of the kernel (if audit_log* is called,
* then a syscall record will be generated automatically for the
* current syscall).
* 5) Netlink interface to user-space.
* 6) Support low-overhead kernel-based filtering to minimize the
* information that must be passed to user-space.
*
* Example user-space utilities: http://people.redhat.com/sgrubb/audit/
*/
#include <linux/init.h>
#include <asm/types.h>
#include <linux/atomic.h>
#include <linux/mm.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/kthread.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <linux/skbuff.h>
#ifdef CONFIG_SECURITY
#include <linux/security.h>
#endif
#include <net/netlink.h>
#include <linux/freezer.h>
#include <linux/tty.h>
#include <linux/pid_namespace.h>
#include "audit.h"
/* No auditing will take place until audit_initialized == AUDIT_INITIALIZED.
* (Initialization happens after skb_init is called.) */
#define AUDIT_DISABLED -1
#define AUDIT_UNINITIALIZED 0
#define AUDIT_INITIALIZED 1
static int audit_initialized;
#define AUDIT_OFF 0
#define AUDIT_ON 1
#define AUDIT_LOCKED 2
int audit_enabled;
int audit_ever_enabled;
EXPORT_SYMBOL_GPL(audit_enabled);
/* Default state when kernel boots without any parameters. */
static int audit_default;
/* If auditing cannot proceed, audit_failure selects what happens. */
static int audit_failure = AUDIT_FAIL_PRINTK;
/*
* If audit records are to be written to the netlink socket, audit_pid
* contains the pid of the auditd process and audit_nlk_portid contains
* the portid to use to send netlink messages to that process.
*/
int audit_pid;
static int audit_nlk_portid;
/* If audit_rate_limit is non-zero, limit the rate of sending audit records
* to that number per second. This prevents DoS attacks, but results in
* audit records being dropped. */
static int audit_rate_limit;
/* Number of outstanding audit_buffers allowed. */
static int audit_backlog_limit = 64;
#define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
static int audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
static int audit_backlog_wait_overflow = 0;
/* The identity of the user shutting down the audit system. */
kuid_t audit_sig_uid = INVALID_UID;
pid_t audit_sig_pid = -1;
u32 audit_sig_sid = 0;
/* Records can be lost in several ways:
0) [suppressed in audit_alloc]
1) out of memory in audit_log_start [kmalloc of struct audit_buffer]
2) out of memory in audit_log_move [alloc_skb]
3) suppressed due to audit_rate_limit
4) suppressed due to audit_backlog_limit
*/
static atomic_t audit_lost = ATOMIC_INIT(0);
/* The netlink socket. */
static struct sock *audit_sock;
/* Hash for inode-based rules */
struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
/* The audit_freelist is a list of pre-allocated audit buffers (if more
* than AUDIT_MAXFREE are in use, the audit buffer is freed instead of
* being placed on the freelist). */
static DEFINE_SPINLOCK(audit_freelist_lock);
static int audit_freelist_count;
static LIST_HEAD(audit_freelist);
static struct sk_buff_head audit_skb_queue;
/* queue of skbs to send to auditd when/if it comes back */
static struct sk_buff_head audit_skb_hold_queue;
static struct task_struct *kauditd_task;
static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait);
/* Serialize requests from userspace. */
DEFINE_MUTEX(audit_cmd_mutex);
/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
* audit records. Since printk uses a 1024 byte buffer, this buffer
* should be at least that large. */
#define AUDIT_BUFSIZ 1024
/* AUDIT_MAXFREE is the number of empty audit_buffers we keep on the
* audit_freelist. Doing so eliminates many kmalloc/kfree calls. */
#define AUDIT_MAXFREE (2*NR_CPUS)
/* The audit_buffer is used when formatting an audit record. The caller
* locks briefly to get the record off the freelist or to allocate the
* buffer, and locks briefly to send the buffer to the netlink layer or
* to place it on a transmit queue. Multiple audit_buffers can be in
* use simultaneously. */
struct audit_buffer {
struct list_head list;
struct sk_buff *skb; /* formatted skb ready to send */
struct audit_context *ctx; /* NULL or associated context */
gfp_t gfp_mask;
};
struct audit_reply {
int pid;
struct sk_buff *skb;
};
static void audit_set_pid(struct audit_buffer *ab, pid_t pid)
{
if (ab) {
struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
nlh->nlmsg_pid = pid;
}
}
void audit_panic(const char *message)
{
switch (audit_failure)
{
case AUDIT_FAIL_SILENT:
break;
case AUDIT_FAIL_PRINTK:
if (printk_ratelimit())
printk(KERN_ERR "audit: %s\n", message);
break;
case AUDIT_FAIL_PANIC:
/* test audit_pid since printk is always losey, why bother? */
if (audit_pid)
panic("audit: %s\n", message);
break;
}
}
static inline int audit_rate_check(void)
{
static unsigned long last_check = 0;
static int messages = 0;
static DEFINE_SPINLOCK(lock);
unsigned long flags;
unsigned long now;
unsigned long elapsed;
int retval = 0;
if (!audit_rate_limit) return 1;
spin_lock_irqsave(&lock, flags);
if (++messages < audit_rate_limit) {
retval = 1;
} else {
now = jiffies;
elapsed = now - last_check;
if (elapsed > HZ) {
last_check = now;
messages = 0;
retval = 1;
}
}
spin_unlock_irqrestore(&lock, flags);
return retval;
}
/**
* audit_log_lost - conditionally log lost audit message event
* @message: the message stating reason for lost audit message
*
* Emit at least 1 message per second, even if audit_rate_check is
* throttling.
* Always increment the lost messages counter.
*/
void audit_log_lost(const char *message)
{
static unsigned long last_msg = 0;
static DEFINE_SPINLOCK(lock);
unsigned long flags;
unsigned long now;
int print;
atomic_inc(&audit_lost);
print = (audit_failure == AUDIT_FAIL_PANIC || !audit_rate_limit);
if (!print) {
spin_lock_irqsave(&lock, flags);
now = jiffies;
if (now - last_msg > HZ) {
print = 1;
last_msg = now;
}
spin_unlock_irqrestore(&lock, flags);
}
if (print) {
if (printk_ratelimit())
printk(KERN_WARNING
"audit: audit_lost=%d audit_rate_limit=%d "
"audit_backlog_limit=%d\n",
atomic_read(&audit_lost),
audit_rate_limit,
audit_backlog_limit);
audit_panic(message);
}
}
static int audit_log_config_change(char *function_name, int new, int old,
int allow_changes)
{
struct audit_buffer *ab;
int rc = 0;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
if (unlikely(!ab))
return rc;
audit_log_format(ab, "%s=%d old=%d", function_name, new, old);
audit_log_session_info(ab);
rc = audit_log_task_context(ab);
if (rc)
allow_changes = 0; /* Something weird, deny request */
audit_log_format(ab, " res=%d", allow_changes);
audit_log_end(ab);
return rc;
}
static int audit_do_config_change(char *function_name, int *to_change, int new)
{
int allow_changes, rc = 0, old = *to_change;
/* check if we are locked */
if (audit_enabled == AUDIT_LOCKED)
allow_changes = 0;
else
allow_changes = 1;
if (audit_enabled != AUDIT_OFF) {
rc = audit_log_config_change(function_name, new, old, allow_changes);
if (rc)
allow_changes = 0;
}
/* If we are allowed, make the change */
if (allow_changes == 1)
*to_change = new;
/* Not allowed, update reason */
else if (rc == 0)
rc = -EPERM;
return rc;
}
static int audit_set_rate_limit(int limit)
{
return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
}
static int audit_set_backlog_limit(int limit)
{
return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
}
static int audit_set_enabled(int state)
{
int rc;
if (state < AUDIT_OFF || state > AUDIT_LOCKED)
return -EINVAL;
rc = audit_do_config_change("audit_enabled", &audit_enabled, state);
if (!rc)
audit_ever_enabled |= !!state;
return rc;
}
static int audit_set_failure(int state)
{
if (state != AUDIT_FAIL_SILENT
&& state != AUDIT_FAIL_PRINTK
&& state != AUDIT_FAIL_PANIC)
return -EINVAL;
return audit_do_config_change("audit_failure", &audit_failure, state);
}
/*
* Queue skbs to be sent to auditd when/if it comes back. These skbs should
* already have been sent via prink/syslog and so if these messages are dropped
* it is not a huge concern since we already passed the audit_log_lost()
* notification and stuff. This is just nice to get audit messages during
* boot before auditd is running or messages generated while auditd is stopped.
* This only holds messages is audit_default is set, aka booting with audit=1
* or building your kernel that way.
*/
static void audit_hold_skb(struct sk_buff *skb)
{
if (audit_default &&
skb_queue_len(&audit_skb_hold_queue) < audit_backlog_limit)
skb_queue_tail(&audit_skb_hold_queue, skb);
else
kfree_skb(skb);
}
/*
* For one reason or another this nlh isn't getting delivered to the userspace
* audit daemon, just send it to printk.
*/
static void audit_printk_skb(struct sk_buff *skb)
{
struct nlmsghdr *nlh = nlmsg_hdr(skb);
char *data = nlmsg_data(nlh);
if (nlh->nlmsg_type != AUDIT_EOE) {
if (printk_ratelimit())
printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, data);
else
audit_log_lost("printk limit exceeded\n");
}
audit_hold_skb(skb);
}
static void kauditd_send_skb(struct sk_buff *skb)
{
int err;
/* take a reference in case we can't send it and we want to hold it */
skb_get(skb);
err = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
if (err < 0) {
BUG_ON(err != -ECONNREFUSED); /* Shouldn't happen */
printk(KERN_ERR "audit: *NO* daemon at audit_pid=%d\n", audit_pid);
audit_log_lost("auditd disappeared\n");
audit_pid = 0;
/* we might get lucky and get this in the next auditd */
audit_hold_skb(skb);
} else
/* drop the extra reference if sent ok */
consume_skb(skb);
}
/*
* flush_hold_queue - empty the hold queue if auditd appears
*
* If auditd just started, drain the queue of messages already
* sent to syslog/printk. Remember loss here is ok. We already
* called audit_log_lost() if it didn't go out normally. so the
* race between the skb_dequeue and the next check for audit_pid
* doesn't matter.
*
* If you ever find kauditd to be too slow we can get a perf win
* by doing our own locking and keeping better track if there
* are messages in this queue. I don't see the need now, but
* in 5 years when I want to play with this again I'll see this
* note and still have no friggin idea what i'm thinking today.
*/
static void flush_hold_queue(void)
{
struct sk_buff *skb;
if (!audit_default || !audit_pid)
return;
skb = skb_dequeue(&audit_skb_hold_queue);
if (likely(!skb))
return;
while (skb && audit_pid) {
kauditd_send_skb(skb);
skb = skb_dequeue(&audit_skb_hold_queue);
}
/*
* if auditd just disappeared but we
* dequeued an skb we need to drop ref
*/
if (skb)
consume_skb(skb);
}
static int kauditd_thread(void *dummy)
{
set_freezable();
while (!kthread_should_stop()) {
struct sk_buff *skb;
DECLARE_WAITQUEUE(wait, current);
flush_hold_queue();
skb = skb_dequeue(&audit_skb_queue);
wake_up(&audit_backlog_wait);
if (skb) {
if (audit_pid)
kauditd_send_skb(skb);
else
audit_printk_skb(skb);
continue;
}
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&kauditd_wait, &wait);
if (!skb_queue_len(&audit_skb_queue)) {
try_to_freeze();
schedule();
}
__set_current_state(TASK_RUNNING);
remove_wait_queue(&kauditd_wait, &wait);
}
return 0;
}
int audit_send_list(void *_dest)
{
struct audit_netlink_list *dest = _dest;
int pid = dest->pid;
struct sk_buff *skb;
/* wait for parent to finish and send an ACK */
mutex_lock(&audit_cmd_mutex);
mutex_unlock(&audit_cmd_mutex);
while ((skb = __skb_dequeue(&dest->q)) != NULL)
netlink_unicast(audit_sock, skb, pid, 0);
kfree(dest);
return 0;
}
struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
int multi, const void *payload, int size)
{
struct sk_buff *skb;
struct nlmsghdr *nlh;
void *data;
int flags = multi ? NLM_F_MULTI : 0;
int t = done ? NLMSG_DONE : type;
skb = nlmsg_new(size, GFP_KERNEL);
if (!skb)
return NULL;
nlh = nlmsg_put(skb, pid, seq, t, size, flags);
if (!nlh)
goto out_kfree_skb;
data = nlmsg_data(nlh);
memcpy(data, payload, size);
return skb;
out_kfree_skb:
kfree_skb(skb);
return NULL;
}
static int audit_send_reply_thread(void *arg)
{
struct audit_reply *reply = (struct audit_reply *)arg;
mutex_lock(&audit_cmd_mutex);
mutex_unlock(&audit_cmd_mutex);
/* Ignore failure. It'll only happen if the sender goes away,
because our timeout is set to infinite. */
netlink_unicast(audit_sock, reply->skb, reply->pid, 0);
kfree(reply);
return 0;
}
/**
* audit_send_reply - send an audit reply message via netlink
* @pid: process id to send reply to
* @seq: sequence number
* @type: audit message type
* @done: done (last) flag
* @multi: multi-part message flag
* @payload: payload data
* @size: payload size
*
* Allocates an skb, builds the netlink message, and sends it to the pid.
* No failure notifications.
*/
static void audit_send_reply(int pid, int seq, int type, int done, int multi,
const void *payload, int size)
{
struct sk_buff *skb;
struct task_struct *tsk;
struct audit_reply *reply = kmalloc(sizeof(struct audit_reply),
GFP_KERNEL);
if (!reply)
return;
skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
if (!skb)
goto out;
reply->pid = pid;
reply->skb = skb;
tsk = kthread_run(audit_send_reply_thread, reply, "audit_send_reply");
if (!IS_ERR(tsk))
return;
kfree_skb(skb);
out:
kfree(reply);
}
/*
* Check for appropriate CAP_AUDIT_ capabilities on incoming audit
* control messages.
*/
static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
{
int err = 0;
/* Only support the initial namespaces for now. */
if ((current_user_ns() != &init_user_ns) ||
(task_active_pid_ns(current) != &init_pid_ns))
return -EPERM;
switch (msg_type) {
case AUDIT_LIST:
case AUDIT_ADD:
case AUDIT_DEL:
return -EOPNOTSUPP;
case AUDIT_GET:
case AUDIT_SET:
case AUDIT_LIST_RULES:
case AUDIT_ADD_RULE:
case AUDIT_DEL_RULE:
case AUDIT_SIGNAL_INFO:
case AUDIT_TTY_GET:
case AUDIT_TTY_SET:
case AUDIT_TRIM:
case AUDIT_MAKE_EQUIV:
if (!netlink_capable(skb, CAP_AUDIT_CONTROL))
err = -EPERM;
break;
case AUDIT_USER:
case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
if (!netlink_capable(skb, CAP_AUDIT_WRITE))
err = -EPERM;
break;
default: /* bad msg */
err = -EINVAL;
}
return err;
}
static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type)
{
int rc = 0;
uid_t uid = from_kuid(&init_user_ns, current_uid());
if (!audit_enabled && msg_type != AUDIT_USER_AVC) {
*ab = NULL;
return rc;
}
*ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
if (unlikely(!*ab))
return rc;
audit_log_format(*ab, "pid=%d uid=%u", task_tgid_vnr(current), uid);
audit_log_session_info(*ab);
audit_log_task_context(*ab);
return rc;
}
static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
u32 seq;
void *data;
struct audit_status *status_get, status_set;
int err;
struct audit_buffer *ab;
u16 msg_type = nlh->nlmsg_type;
struct audit_sig_info *sig_data;
char *ctx = NULL;
u32 len;
err = audit_netlink_ok(skb, msg_type);
if (err)
return err;
/* As soon as there's any sign of userspace auditd,
* start kauditd to talk to it */
if (!kauditd_task) {
kauditd_task = kthread_run(kauditd_thread, NULL, "kauditd");
if (IS_ERR(kauditd_task)) {
err = PTR_ERR(kauditd_task);
kauditd_task = NULL;
return err;
}
}
seq = nlh->nlmsg_seq;
data = nlmsg_data(nlh);
switch (msg_type) {
case AUDIT_GET:
status_set.mask = 0;
status_set.enabled = audit_enabled;
status_set.failure = audit_failure;
status_set.pid = audit_pid;
status_set.rate_limit = audit_rate_limit;
status_set.backlog_limit = audit_backlog_limit;
status_set.lost = atomic_read(&audit_lost);
status_set.backlog = skb_queue_len(&audit_skb_queue);
audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
&status_set, sizeof(status_set));
break;
case AUDIT_SET:
if (nlmsg_len(nlh) < sizeof(struct audit_status))
return -EINVAL;
status_get = (struct audit_status *)data;
if (status_get->mask & AUDIT_STATUS_ENABLED) {
err = audit_set_enabled(status_get->enabled);
if (err < 0)
return err;
}
if (status_get->mask & AUDIT_STATUS_FAILURE) {
err = audit_set_failure(status_get->failure);
if (err < 0)
return err;
}
if (status_get->mask & AUDIT_STATUS_PID) {
/* NOTE: we are using task_tgid_vnr() below because
* the s.pid value is relative to the namespace
* of the caller; at present this doesn't matter
* much since you can really only run auditd
* from the initial pid namespace, but something
* to keep in mind if this changes */
int new_pid = status_get->pid;
if (audit_enabled != AUDIT_OFF)
audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
audit_pid = new_pid;
audit_nlk_portid = NETLINK_CB(skb).portid;
}
if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
err = audit_set_rate_limit(status_get->rate_limit);
if (err < 0)
return err;
}
if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
err = audit_set_backlog_limit(status_get->backlog_limit);
break;
case AUDIT_USER:
case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG:
case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2:
if (!audit_enabled && msg_type != AUDIT_USER_AVC)
return 0;
err = audit_filter_user(msg_type);
if (err == 1) {
err = 0;
if (msg_type == AUDIT_USER_TTY) {
err = tty_audit_push_current();
if (err)
break;
}
audit_log_common_recv_msg(&ab, msg_type);
if (msg_type != AUDIT_USER_TTY)
audit_log_format(ab, " msg='%.1024s'",
(char *)data);
else {
int size;
audit_log_format(ab, " data=");
size = nlmsg_len(nlh);
if (size > 0 &&
((unsigned char *)data)[size - 1] == '\0')
size--;
audit_log_n_untrustedstring(ab, data, size);
}
audit_set_pid(ab, NETLINK_CB(skb).portid);
audit_log_end(ab);
}
break;
case AUDIT_ADD_RULE:
case AUDIT_DEL_RULE:
if (nlmsg_len(nlh) < sizeof(struct audit_rule_data))
return -EINVAL;
if (audit_enabled == AUDIT_LOCKED) {
audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
audit_log_end(ab);
return -EPERM;
}
/* fallthrough */
case AUDIT_LIST_RULES:
err = audit_receive_filter(msg_type, NETLINK_CB(skb).portid,
seq, data, nlmsg_len(nlh));
break;
case AUDIT_TRIM:
audit_trim_trees();
audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
audit_log_format(ab, " op=trim res=1");
audit_log_end(ab);
break;
case AUDIT_MAKE_EQUIV: {
void *bufp = data;
u32 sizes[2];
size_t msglen = nlmsg_len(nlh);
char *old, *new;
err = -EINVAL;
if (msglen < 2 * sizeof(u32))
break;
memcpy(sizes, bufp, 2 * sizeof(u32));
bufp += 2 * sizeof(u32);
msglen -= 2 * sizeof(u32);
old = audit_unpack_string(&bufp, &msglen, sizes[0]);
if (IS_ERR(old)) {
err = PTR_ERR(old);
break;
}
new = audit_unpack_string(&bufp, &msglen, sizes[1]);
if (IS_ERR(new)) {
err = PTR_ERR(new);
kfree(old);
break;
}
/* OK, here comes... */
err = audit_tag_tree(old, new);
audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
audit_log_format(ab, " op=make_equiv old=");
audit_log_untrustedstring(ab, old);
audit_log_format(ab, " new=");
audit_log_untrustedstring(ab, new);
audit_log_format(ab, " res=%d", !err);
audit_log_end(ab);
kfree(old);
kfree(new);
break;
}
case AUDIT_SIGNAL_INFO:
len = 0;
if (audit_sig_sid) {
err = security_secid_to_secctx(audit_sig_sid, &ctx, &len);
if (err)
return err;
}
sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
if (!sig_data) {
if (audit_sig_sid)
security_release_secctx(ctx, len);
return -ENOMEM;
}
sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
sig_data->pid = audit_sig_pid;
if (audit_sig_sid) {
memcpy(sig_data->ctx, ctx, len);
security_release_secctx(ctx, len);
}
audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_SIGNAL_INFO,
0, 0, sig_data, sizeof(*sig_data) + len);
kfree(sig_data);
break;
case AUDIT_TTY_GET: {
struct audit_tty_status s;
struct task_struct *tsk = current;
spin_lock(&tsk->sighand->siglock);
s.enabled = tsk->signal->audit_tty != 0;
s.log_passwd = tsk->signal->audit_tty_log_passwd;
spin_unlock(&tsk->sighand->siglock);
audit_send_reply(NETLINK_CB(skb).portid, seq,
AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
break;
}
case AUDIT_TTY_SET: {
struct audit_tty_status s;
struct task_struct *tsk = current;
memset(&s, 0, sizeof(s));
/* guard against past and future API changes */
memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
if ((s.enabled != 0 && s.enabled != 1) ||
(s.log_passwd != 0 && s.log_passwd != 1))
return -EINVAL;
spin_lock(&tsk->sighand->siglock);
tsk->signal->audit_tty = s.enabled;
tsk->signal->audit_tty_log_passwd = s.log_passwd;
spin_unlock(&tsk->sighand->siglock);
break;
}
default:
err = -EINVAL;
break;
}
return err < 0 ? err : 0;
}
/*
* Get message from skb. Each message is processed by audit_receive_msg.
* Malformed skbs with wrong length are discarded silently.
*/
static void audit_receive_skb(struct sk_buff *skb)
{
struct nlmsghdr *nlh;
/*
* len MUST be signed for nlmsg_next to be able to dec it below 0
* if the nlmsg_len was not aligned
*/
int len;
int err;
nlh = nlmsg_hdr(skb);
len = skb->len;
while (nlmsg_ok(nlh, len)) {
err = audit_receive_msg(skb, nlh);
/* if err or if this message says it wants a response */
if (err || (nlh->nlmsg_flags & NLM_F_ACK))
netlink_ack(skb, nlh, err);
nlh = nlmsg_next(nlh, &len);
}
}
/* Receive messages from netlink socket. */
static void audit_receive(struct sk_buff *skb)
{
mutex_lock(&audit_cmd_mutex);
audit_receive_skb(skb);
mutex_unlock(&audit_cmd_mutex);
}
/* Initialize audit support at boot time. */
static int __init audit_init(void)
{
int i;
struct netlink_kernel_cfg cfg = {
.input = audit_receive,
};
if (audit_initialized == AUDIT_DISABLED)
return 0;
printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
audit_default ? "enabled" : "disabled");
audit_sock = netlink_kernel_create(&init_net, NETLINK_AUDIT, &cfg);
if (!audit_sock)
audit_panic("cannot initialize netlink socket");
else
audit_sock->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
skb_queue_head_init(&audit_skb_queue);
skb_queue_head_init(&audit_skb_hold_queue);
audit_initialized = AUDIT_INITIALIZED;
audit_enabled = audit_default;
audit_ever_enabled |= !!audit_default;
audit_log(NULL, GFP_KERNEL, AUDIT_KERNEL, "initialized");
for (i = 0; i < AUDIT_INODE_BUCKETS; i++)
INIT_LIST_HEAD(&audit_inode_hash[i]);
return 0;
}
__initcall(audit_init);
/* Process kernel command-line parameter at boot time. audit=0 or audit=1. */
static int __init audit_enable(char *str)
{
audit_default = !!simple_strtol(str, NULL, 0);
if (!audit_default)
audit_initialized = AUDIT_DISABLED;
printk(KERN_INFO "audit: %s", audit_default ? "enabled" : "disabled");
if (audit_initialized == AUDIT_INITIALIZED) {
audit_enabled = audit_default;
audit_ever_enabled |= !!audit_default;
} else if (audit_initialized == AUDIT_UNINITIALIZED) {
printk(" (after initialization)");
} else {
printk(" (until reboot)");
}
printk("\n");
return 1;
}
__setup("audit=", audit_enable);
static void audit_buffer_free(struct audit_buffer *ab)
{
unsigned long flags;
if (!ab)
return;
if (ab->skb)
kfree_skb(ab->skb);
spin_lock_irqsave(&audit_freelist_lock, flags);
if (audit_freelist_count > AUDIT_MAXFREE)
kfree(ab);
else {
audit_freelist_count++;
list_add(&ab->list, &audit_freelist);
}
spin_unlock_irqrestore(&audit_freelist_lock, flags);
}
static struct audit_buffer * audit_buffer_alloc(struct audit_context *ctx,
gfp_t gfp_mask, int type)
{
unsigned long flags;
struct audit_buffer *ab = NULL;
struct nlmsghdr *nlh;
spin_lock_irqsave(&audit_freelist_lock, flags);
if (!list_empty(&audit_freelist)) {
ab = list_entry(audit_freelist.next,
struct audit_buffer, list);
list_del(&ab->list);
--audit_freelist_count;
}
spin_unlock_irqrestore(&audit_freelist_lock, flags);
if (!ab) {
ab = kmalloc(sizeof(*ab), gfp_mask);
if (!ab)
goto err;
}
ab->ctx = ctx;
ab->gfp_mask = gfp_mask;
ab->skb = nlmsg_new(AUDIT_BUFSIZ, gfp_mask);