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audit.c 40.16 KiB
/* 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/audit.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <linux/skbuff.h>
#ifdef CONFIG_SECURITY
#include <linux/security.h>
#endif
#include <linux/netlink.h>
#include <linux/freezer.h>
#include <linux/tty.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_pid contains
* the pid to use to send netlink messages to that process.
*/
int audit_pid;
static int audit_nlk_pid;
/* 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;
static int audit_backlog_wait_time = 60 * HZ;
static int audit_backlog_wait_overflow = 0;
/* The identity of the user shutting down the audit system. */
uid_t audit_sig_uid = -1;
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,
uid_t loginuid, u32 sessionid, u32 sid,
int allow_changes)
{
struct audit_buffer *ab;
int rc = 0;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
audit_log_format(ab, "%s=%d old=%d auid=%u ses=%u", function_name, new,
old, loginuid, sessionid);
if (sid) {
char *ctx = NULL;
u32 len;
rc = security_secid_to_secctx(sid, &ctx, &len); if (rc) {
audit_log_format(ab, " sid=%u", sid);
allow_changes = 0; /* Something weird, deny request */
} else {
audit_log_format(ab, " subj=%s", ctx);
security_release_secctx(ctx, len);
}
}
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, uid_t loginuid, u32 sessionid,
u32 sid)
{
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, loginuid,
sessionid, sid, 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, uid_t loginuid, u32 sessionid,
u32 sid)
{
return audit_do_config_change("audit_rate_limit", &audit_rate_limit,
limit, loginuid, sessionid, sid);
}
static int audit_set_backlog_limit(int limit, uid_t loginuid, u32 sessionid,
u32 sid)
{
return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit,
limit, loginuid, sessionid, sid);
}
static int audit_set_enabled(int state, uid_t loginuid, u32 sessionid, u32 sid)
{
int rc;
if (state < AUDIT_OFF || state > AUDIT_LOCKED)
return -EINVAL;
rc = audit_do_config_change("audit_enabled", &audit_enabled, state,
loginuid, sessionid, sid);
if (!rc)
audit_ever_enabled |= !!state;
return rc;
}
static int audit_set_failure(int state, uid_t loginuid, u32 sessionid, u32 sid)
{
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,
loginuid, sessionid, sid);
}
/*
* 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_pid, 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);
}
static int kauditd_thread(void *dummy)
{
struct sk_buff *skb;
set_freezable();
while (!kthread_should_stop()) {
/*
* 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.
*/
if (audit_default && audit_pid) {
skb = skb_dequeue(&audit_skb_hold_queue);
if (unlikely(skb)) {
while (skb && audit_pid) {
kauditd_send_skb(skb);
skb = skb_dequeue(&audit_skb_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);
} else {
DECLARE_WAITQUEUE(wait, current);
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;
}
static int audit_prepare_user_tty(pid_t pid, uid_t loginuid, u32 sessionid)
{
struct task_struct *tsk;
int err;
rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (!tsk) {
rcu_read_unlock();
return -ESRCH;
}
get_task_struct(tsk);
rcu_read_unlock();
err = tty_audit_push_task(tsk, loginuid, sessionid);
put_task_struct(tsk);
return err;
}
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_NEW(skb, pid, seq, t, size, flags);
data = NLMSG_DATA(nlh);
memcpy(data, payload, size);
return skb;
nlmsg_failure: /* Used by NLMSG_NEW */
if (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;
switch (msg_type) {
case AUDIT_GET:
case AUDIT_LIST:
case AUDIT_LIST_RULES:
case AUDIT_SET:
case AUDIT_ADD:
case AUDIT_ADD_RULE:
case AUDIT_DEL:
case AUDIT_DEL_RULE:
case AUDIT_SIGNAL_INFO:
case AUDIT_TTY_GET:
case AUDIT_TTY_SET:
case AUDIT_TRIM:
case AUDIT_MAKE_EQUIV:
if (!capable(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 (!capable(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,
u32 pid, u32 uid, uid_t auid, u32 ses,
u32 sid)
{
int rc = 0;
char *ctx = NULL;
u32 len;
if (!audit_enabled) {
*ab = NULL;
return rc; }
*ab = audit_log_start(NULL, GFP_KERNEL, msg_type);
audit_log_format(*ab, "pid=%d uid=%u auid=%u ses=%u",
pid, uid, auid, ses);
if (sid) {
rc = security_secid_to_secctx(sid, &ctx, &len);
if (rc)
audit_log_format(*ab, " ssid=%u", sid);
else {
audit_log_format(*ab, " subj=%s", ctx);
security_release_secctx(ctx, len);
}
}
return rc;
}
static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
u32 uid, pid, seq, sid;
void *data;
struct audit_status *status_get, status_set;
int err;
struct audit_buffer *ab;
u16 msg_type = nlh->nlmsg_type;
uid_t loginuid; /* loginuid of sender */
u32 sessionid;
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;
}
pid = NETLINK_CREDS(skb)->pid;
uid = NETLINK_CREDS(skb)->uid;
loginuid = audit_get_loginuid(current);
sessionid = audit_get_sessionid(current);
security_task_getsecid(current, &sid);
seq = nlh->nlmsg_seq;
data = NLMSG_DATA(nlh);
switch (msg_type) {
case AUDIT_GET:
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).pid, seq, AUDIT_GET, 0, 0,
&status_set, sizeof(status_set));
break;
case AUDIT_SET:
if (nlh->nlmsg_len < 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,
loginuid, sessionid, sid);
if (err < 0)
return err;
}
if (status_get->mask & AUDIT_STATUS_FAILURE) {
err = audit_set_failure(status_get->failure,
loginuid, sessionid, sid);
if (err < 0)
return err;
}
if (status_get->mask & AUDIT_STATUS_PID) {
int new_pid = status_get->pid;
if (audit_enabled != AUDIT_OFF)
audit_log_config_change("audit_pid", new_pid,
audit_pid, loginuid,
sessionid, sid, 1);
audit_pid = new_pid;
audit_nlk_pid = NETLINK_CB(skb).pid;
}
if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
err = audit_set_rate_limit(status_get->rate_limit,
loginuid, sessionid, sid);
if (err < 0)
return err;
}
if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
err = audit_set_backlog_limit(status_get->backlog_limit,
loginuid, sessionid, sid);
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(&NETLINK_CB(skb));
if (err == 1) {
err = 0;
if (msg_type == AUDIT_USER_TTY) {
err = audit_prepare_user_tty(pid, loginuid,
sessionid);
if (err)
break;
}
audit_log_common_recv_msg(&ab, msg_type, pid, uid,
loginuid, sessionid, sid);
if (msg_type != AUDIT_USER_TTY)
audit_log_format(ab, " msg='%.1024s'",
(char *)data);
else {
int size;
audit_log_format(ab, " msg=");
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, pid);
audit_log_end(ab);
}
break;
case AUDIT_ADD:
case AUDIT_DEL: if (nlmsg_len(nlh) < sizeof(struct audit_rule))
return -EINVAL;
if (audit_enabled == AUDIT_LOCKED) {
audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
uid, loginuid, sessionid, sid);
audit_log_format(ab, " audit_enabled=%d res=0",
audit_enabled);
audit_log_end(ab);
return -EPERM;
}
/* fallthrough */
case AUDIT_LIST:
err = audit_receive_filter(msg_type, NETLINK_CB(skb).pid,
uid, seq, data, nlmsg_len(nlh),
loginuid, sessionid, sid);
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, pid,
uid, loginuid, sessionid, sid);
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).pid,
uid, seq, data, nlmsg_len(nlh),
loginuid, sessionid, sid);
break;
case AUDIT_TRIM:
audit_trim_trees();
audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE, pid,
uid, loginuid, sessionid, sid);
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, pid,
uid, loginuid, sessionid, sid);
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 = 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).pid, 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;
unsigned long flags;
rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (tsk && lock_task_sighand(tsk, &flags)) {
s.enabled = tsk->signal->audit_tty != 0;
unlock_task_sighand(tsk, &flags);
} else
err = -ESRCH;
rcu_read_unlock();
if (!err)
audit_send_reply(NETLINK_CB(skb).pid, seq,
AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
break;
}
case AUDIT_TTY_SET: {
struct audit_tty_status *s;
struct task_struct *tsk;
unsigned long flags;
if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
return -EINVAL;
s = data;
if (s->enabled != 0 && s->enabled != 1)
return -EINVAL;
rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (tsk && lock_task_sighand(tsk, &flags)) {
tsk->signal->audit_tty = s->enabled != 0; unlock_task_sighand(tsk, &flags);
} else
err = -ESRCH;
rcu_read_unlock();
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;
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, 0,
audit_receive, NULL, THIS_MODULE);
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);
if (!ab->skb)
goto nlmsg_failure;
nlh = NLMSG_NEW(ab->skb, 0, 0, type, 0, 0);
return ab;
nlmsg_failure: /* Used by NLMSG_NEW */
kfree_skb(ab->skb);
ab->skb = NULL;
err:
audit_buffer_free(ab);
return NULL;
}
/**
* audit_serial - compute a serial number for the audit record
*
* Compute a serial number for the audit record. Audit records are
* written to user-space as soon as they are generated, so a complete
* audit record may be written in several pieces. The timestamp of the
* record and this serial number are used by the user-space tools to
* determine which pieces belong to the same audit record. The
* (timestamp,serial) tuple is unique for each syscall and is live from
* syscall entry to syscall exit.
*
* NOTE: Another possibility is to store the formatted records off the
* audit context (for those records that have a context), and emit them
* all at syscall exit. However, this could delay the reporting of
* significant errors until syscall exit (or never, if the system
* halts).
*/
unsigned int audit_serial(void)
{
static DEFINE_SPINLOCK(serial_lock);
static unsigned int serial = 0;
unsigned long flags;
unsigned int ret;
spin_lock_irqsave(&serial_lock, flags);
do {
ret = ++serial;
} while (unlikely(!ret));
spin_unlock_irqrestore(&serial_lock, flags);
return ret;
}
static inline void audit_get_stamp(struct audit_context *ctx,
struct timespec *t, unsigned int *serial)
{
if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
*t = CURRENT_TIME;
*serial = audit_serial();
}
}
/* Obtain an audit buffer. This routine does locking to obtain the * audit buffer, but then no locking is required for calls to
* audit_log_*format. If the tsk is a task that is currently in a
* syscall, then the syscall is marked as auditable and an audit record
* will be written at syscall exit. If there is no associated task, tsk
* should be NULL. */
/**
* audit_log_start - obtain an audit buffer
* @ctx: audit_context (may be NULL)
* @gfp_mask: type of allocation
* @type: audit message type
*
* Returns audit_buffer pointer on success or NULL on error.
*
* Obtain an audit buffer. This routine does locking to obtain the
* audit buffer, but then no locking is required for calls to
* audit_log_*format. If the task (ctx) is a task that is currently in a
* syscall, then the syscall is marked as auditable and an audit record
* will be written at syscall exit. If there is no associated task, then
* task context (ctx) should be NULL.
*/
struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
int type)
{
struct audit_buffer *ab = NULL;
struct timespec t;
unsigned int uninitialized_var(serial);
int reserve;
unsigned long timeout_start = jiffies;
if (audit_initialized != AUDIT_INITIALIZED)
return NULL;
if (unlikely(audit_filter_type(type)))
return NULL;
if (gfp_mask & __GFP_WAIT)
reserve = 0;
else
reserve = 5; /* Allow atomic callers to go up to five
entries over the normal backlog limit */
while (audit_backlog_limit
&& skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time
&& time_before(jiffies, timeout_start + audit_backlog_wait_time)) {
/* Wait for auditd to drain the queue a little */
DECLARE_WAITQUEUE(wait, current);
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&audit_backlog_wait, &wait);
if (audit_backlog_limit &&
skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
schedule_timeout(timeout_start + audit_backlog_wait_time - jiffies);
__set_current_state(TASK_RUNNING);
remove_wait_queue(&audit_backlog_wait, &wait);
continue;
}
if (audit_rate_check() && printk_ratelimit())
printk(KERN_WARNING
"audit: audit_backlog=%d > "
"audit_backlog_limit=%d\n",
skb_queue_len(&audit_skb_queue),
audit_backlog_limit);
audit_log_lost("backlog limit exceeded");
audit_backlog_wait_time = audit_backlog_wait_overflow;
wake_up(&audit_backlog_wait);
return NULL; }
ab = audit_buffer_alloc(ctx, gfp_mask, type);
if (!ab) {
audit_log_lost("out of memory in audit_log_start");
return NULL;
}
audit_get_stamp(ab->ctx, &t, &serial);
audit_log_format(ab, "audit(%lu.%03lu:%u): ",
t.tv_sec, t.tv_nsec/1000000, serial);
return ab;
}
/**
* audit_expand - expand skb in the audit buffer
* @ab: audit_buffer
* @extra: space to add at tail of the skb
*
* Returns 0 (no space) on failed expansion, or available space if
* successful.
*/
static inline int audit_expand(struct audit_buffer *ab, int extra)
{
struct sk_buff *skb = ab->skb;
int oldtail = skb_tailroom(skb);
int ret = pskb_expand_head(skb, 0, extra, ab->gfp_mask);
int newtail = skb_tailroom(skb);
if (ret < 0) {
audit_log_lost("out of memory in audit_expand");
return 0;
}
skb->truesize += newtail - oldtail;
return newtail;
}
/*
* Format an audit message into the audit buffer. If there isn't enough
* room in the audit buffer, more room will be allocated and vsnprint
* will be called a second time. Currently, we assume that a printk
* can't format message larger than 1024 bytes, so we don't either.
*/
static void audit_log_vformat(struct audit_buffer *ab, const char *fmt,
va_list args)
{
int len, avail;
struct sk_buff *skb;
va_list args2;
if (!ab)
return;
BUG_ON(!ab->skb);
skb = ab->skb;
avail = skb_tailroom(skb);
if (avail == 0) {
avail = audit_expand(ab, AUDIT_BUFSIZ);
if (!avail)
goto out;
}
va_copy(args2, args);
len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args);
if (len >= avail) {
/* The printk buffer is 1024 bytes long, so if we get
* here and AUDIT_BUFSIZ is at least 1024, then we can
* log everything that printk could have logged. */
avail = audit_expand(ab, max_t(unsigned, AUDIT_BUFSIZ, 1+len-avail));
if (!avail)
goto out_va_end;
len = vsnprintf(skb_tail_pointer(skb), avail, fmt, args2);
}
if (len > 0)
skb_put(skb, len);
out_va_end:
va_end(args2);
out:
return;
}
/**
* audit_log_format - format a message into the audit buffer.
* @ab: audit_buffer
* @fmt: format string
* @...: optional parameters matching @fmt string
*
* All the work is done in audit_log_vformat.
*/
void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
{
va_list args;
if (!ab)
return;
va_start(args, fmt);
audit_log_vformat(ab, fmt, args);
va_end(args);
}
/**
* audit_log_hex - convert a buffer to hex and append it to the audit skb
* @ab: the audit_buffer
* @buf: buffer to convert to hex
* @len: length of @buf to be converted
*
* No return value; failure to expand is silently ignored.
*
* This function will take the passed buf and convert it into a string of
* ascii hex digits. The new string is placed onto the skb.
*/
void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf,
size_t len)
{
int i, avail, new_len;
unsigned char *ptr;
struct sk_buff *skb;
static const unsigned char *hex = "0123456789ABCDEF";
if (!ab)
return;
BUG_ON(!ab->skb);
skb = ab->skb;
avail = skb_tailroom(skb);
new_len = len<<1;
if (new_len >= avail) {
/* Round the buffer request up to the next multiple */
new_len = AUDIT_BUFSIZ*(((new_len-avail)/AUDIT_BUFSIZ) + 1);
avail = audit_expand(ab, new_len);
if (!avail)
return;
}
ptr = skb_tail_pointer(skb);
for (i=0; i<len; i++) {
*ptr++ = hex[(buf[i] & 0xF0)>>4]; /* Upper nibble */
*ptr++ = hex[buf[i] & 0x0F]; /* Lower nibble */ }
*ptr = 0;
skb_put(skb, len << 1); /* new string is twice the old string */
}
/*
* Format a string of no more than slen characters into the audit buffer,
* enclosed in quote marks.
*/
void audit_log_n_string(struct audit_buffer *ab, const char *string,
size_t slen)
{
int avail, new_len;
unsigned char *ptr;
struct sk_buff *skb;
if (!ab)
return;
BUG_ON(!ab->skb);
skb = ab->skb;
avail = skb_tailroom(skb);
new_len = slen + 3; /* enclosing quotes + null terminator */
if (new_len > avail) {
avail = audit_expand(ab, new_len);
if (!avail)
return;
}
ptr = skb_tail_pointer(skb);
*ptr++ = '"';
memcpy(ptr, string, slen);
ptr += slen;
*ptr++ = '"';
*ptr = 0;
skb_put(skb, slen + 2); /* don't include null terminator */
}
/**
* audit_string_contains_control - does a string need to be logged in hex
* @string: string to be checked
* @len: max length of the string to check
*/
int audit_string_contains_control(const char *string, size_t len)
{
const unsigned char *p;
for (p = string; p < (const unsigned char *)string + len; p++) {
if (*p == '"' || *p < 0x21 || *p > 0x7e)
return 1;
}
return 0;
}
/**
* audit_log_n_untrustedstring - log a string that may contain random characters
* @ab: audit_buffer
* @len: length of string (not including trailing null)
* @string: string to be logged
*
* This code will escape a string that is passed to it if the string
* contains a control character, unprintable character, double quote mark,
* or a space. Unescaped strings will start and end with a double quote mark.
* Strings that are escaped are printed in hex (2 digits per char).
*
* The caller specifies the number of characters in the string to log, which may
* or may not be the entire string.
*/
void audit_log_n_untrustedstring(struct audit_buffer *ab, const char *string,
size_t len)
{
if (audit_string_contains_control(string, len)) audit_log_n_hex(ab, string, len);
else
audit_log_n_string(ab, string, len);
}
/**
* audit_log_untrustedstring - log a string that may contain random characters
* @ab: audit_buffer
* @string: string to be logged
*
* Same as audit_log_n_untrustedstring(), except that strlen is used to
* determine string length.
*/
void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
{
audit_log_n_untrustedstring(ab, string, strlen(string));
}
/* This is a helper-function to print the escaped d_path */
void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
const struct path *path)
{
char *p, *pathname;
if (prefix)
audit_log_format(ab, "%s", prefix);
/* We will allow 11 spaces for ' (deleted)' to be appended */
pathname = kmalloc(PATH_MAX+11, ab->gfp_mask);
if (!pathname) {
audit_log_string(ab, "<no_memory>");
return;
}
p = d_path(path, pathname, PATH_MAX+11);
if (IS_ERR(p)) { /* Should never happen since we send PATH_MAX */
/* FIXME: can we save some information here? */
audit_log_string(ab, "<too_long>");
} else
audit_log_untrustedstring(ab, p);
kfree(pathname);
}
void audit_log_key(struct audit_buffer *ab, char *key)
{
audit_log_format(ab, " key=");
if (key)
audit_log_untrustedstring(ab, key);
else
audit_log_format(ab, "(null)");
}
/**
* audit_log_end - end one audit record
* @ab: the audit_buffer
*
* The netlink_* functions cannot be called inside an irq context, so
* the audit buffer is placed on a queue and a tasklet is scheduled to
* remove them from the queue outside the irq context. May be called in
* any context.
*/
void audit_log_end(struct audit_buffer *ab)
{
if (!ab)
return;
if (!audit_rate_check()) {
audit_log_lost("rate limit exceeded");
} else {
struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
nlh->nlmsg_len = ab->skb->len - NLMSG_SPACE(0);
if (audit_pid) {
skb_queue_tail(&audit_skb_queue, ab->skb);
wake_up_interruptible(&kauditd_wait);
} else {
audit_printk_skb(ab->skb);
}
ab->skb = NULL;
}
audit_buffer_free(ab);
}
/**
* audit_log - Log an audit record
* @ctx: audit context
* @gfp_mask: type of allocation
* @type: audit message type
* @fmt: format string to use
* @...: variable parameters matching the format string
*
* This is a convenience function that calls audit_log_start,
* audit_log_vformat, and audit_log_end. It may be called
* in any context.
*/
void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
const char *fmt, ...)
{
struct audit_buffer *ab;
va_list args;
ab = audit_log_start(ctx, gfp_mask, type);
if (ab) {
va_start(args, fmt);
audit_log_vformat(ab, fmt, args);
va_end(args);
audit_log_end(ab);
}
}
#ifdef CONFIG_SECURITY
/**
* audit_log_secctx - Converts and logs SELinux context
* @ab: audit_buffer
* @secid: security number
*
* This is a helper function that calls security_secid_to_secctx to convert
* secid to secctx and then adds the (converted) SELinux context to the audit
* log by calling audit_log_format, thus also preventing leak of internal secid
* to userspace. If secid cannot be converted audit_panic is called.
*/
void audit_log_secctx(struct audit_buffer *ab, u32 secid)
{
u32 len;
char *secctx;
if (security_secid_to_secctx(secid, &secctx, &len)) {
audit_panic("Cannot convert secid to context");
} else {
audit_log_format(ab, " obj=%s", secctx);
security_release_secctx(secctx, len);
}
}
EXPORT_SYMBOL(audit_log_secctx);
#endif
EXPORT_SYMBOL(audit_log_start);
EXPORT_SYMBOL(audit_log_end);
EXPORT_SYMBOL(audit_log_format);
EXPORT_SYMBOL(audit_log);