/* 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;

  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. */

  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
  ", message);

  		break;
  	case AUDIT_FAIL_PANIC:

  		/* test audit_pid since printk is always losey, why bother? */
  		if (audit_pid)
  			panic("audit: %s
  ", 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
  ",
  				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
  ", nlh->nlmsg_type, data);
  		else
  			audit_log_lost("printk limit exceeded
  ");
  	}
  
  	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
  ", audit_pid);

  		audit_log_lost("auditd disappeared
  ");

  		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 (!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)

  {
  	int rc = 0;

  	uid_t uid = from_kuid(&init_user_ns, current_uid());

  
  	if (!audit_enabled) {
  		*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.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 (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);

  			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) {

  			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(sizeof(s), (size_t)nlh->nlmsg_len));
  		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)
  ",
  	       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("
  ");

  	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 err;

  	nlh = nlmsg_put(ab->skb, 0, 0, type, 0, 0);
  	if (!nlh)
  		goto out_kfree_skb;

  	return ab;

  out_kfree_skb:

  	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();
  	}
  }

  /*
   * Wait for auditd to drain the queue a little
   */
  static void wait_for_auditd(unsigned long sleep_time)
  {
  	DECLARE_WAITQUEUE(wait, current);

  	set_current_state(TASK_UNINTERRUPTIBLE);

  	add_wait_queue(&audit_backlog_wait, &wait);
  
  	if (audit_backlog_limit &&
  	    skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
  		schedule_timeout(sleep_time);
  
  	__set_current_state(TASK_RUNNING);
  	remove_wait_queue(&audit_backlog_wait, &wait);
  }

  /* 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) {
  			unsigned long sleep_time;

  			sleep_time = timeout_start + audit_backlog_wait_time -
  					jiffies;

  			if ((long)sleep_time > 0) {

  				wait_for_auditd(sleep_time);

  				continue;
  			}

  		}

  		if (audit_rate_check() && printk_ratelimit())

  			printk(KERN_WARNING
  			       "audit: audit_backlog=%d > "
  			       "audit_backlog_limit=%d
  ",
  			       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_session_info(struct audit_buffer *ab)
  {
  	u32 sessionid = audit_get_sessionid(current);
  	uid_t auid = from_kuid(&init_user_ns, audit_get_loginuid(current));

  	audit_log_format(ab, " auid=%u ses=%u
  ", auid, sessionid);

  }

  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)");
  }

  void audit_log_cap(struct audit_buffer *ab, char *prefix, kernel_cap_t *cap)
  {
  	int i;
  
  	audit_log_format(ab, " %s=", prefix);
  	CAP_FOR_EACH_U32(i) {
  		audit_log_format(ab, "%08x",
  				 cap->cap[(_KERNEL_CAPABILITY_U32S-1) - i]);
  	}
  }
  
  void audit_log_fcaps(struct audit_buffer *ab, struct audit_names *name)
  {
  	kernel_cap_t *perm = &name->fcap.permitted;
  	kernel_cap_t *inh = &name->fcap.inheritable;
  	int log = 0;
  
  	if (!cap_isclear(*perm)) {
  		audit_log_cap(ab, "cap_fp", perm);
  		log = 1;
  	}
  	if (!cap_isclear(*inh)) {
  		audit_log_cap(ab, "cap_fi", inh);
  		log = 1;
  	}
  
  	if (log)
  		audit_log_format(ab, " cap_fe=%d cap_fver=%x",
  				 name->fcap.fE, name->fcap_ver);
  }
  
  static inline int audit_copy_fcaps(struct audit_names *name,
  				   const struct dentry *dentry)
  {
  	struct cpu_vfs_cap_data caps;
  	int rc;
  
  	if (!dentry)
  		return 0;
  
  	rc = get_vfs_caps_from_disk(dentry, &caps);
  	if (rc)
  		return rc;
  
  	name->fcap.permitted = caps.permitted;
  	name->fcap.inheritable = caps.inheritable;
  	name->fcap.fE = !!(caps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE);
  	name->fcap_ver = (caps.magic_etc & VFS_CAP_REVISION_MASK) >>
  				VFS_CAP_REVISION_SHIFT;
  
  	return 0;
  }
  
  /* Copy inode data into an audit_names. */
  void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
  		      const struct inode *inode)
  {
  	name->ino   = inode->i_ino;
  	name->dev   = inode->i_sb->s_dev;
  	name->mode  = inode->i_mode;
  	name->uid   = inode->i_uid;
  	name->gid   = inode->i_gid;
  	name->rdev  = inode->i_rdev;
  	security_inode_getsecid(inode, &name->osid);
  	audit_copy_fcaps(name, dentry);
  }
  
  /**
   * audit_log_name - produce AUDIT_PATH record from struct audit_names
   * @context: audit_context for the task
   * @n: audit_names structure with reportable details
   * @path: optional path to report instead of audit_names->name
   * @record_num: record number to report when handling a list of names
   * @call_panic: optional pointer to int that will be updated if secid fails
   */
  void audit_log_name(struct audit_context *context, struct audit_names *n,
  		    struct path *path, int record_num, int *call_panic)
  {
  	struct audit_buffer *ab;
  	ab = audit_log_start(context, GFP_KERNEL, AUDIT_PATH);
  	if (!ab)
  		return;
  
  	audit_log_format(ab, "item=%d", record_num);
  
  	if (path)
  		audit_log_d_path(ab, " name=", path);
  	else if (n->name) {
  		switch (n->name_len) {
  		case AUDIT_NAME_FULL:
  			/* log the full path */
  			audit_log_format(ab, " name=");
  			audit_log_untrustedstring(ab, n->name->name);
  			break;
  		case 0:
  			/* name was specified as a relative path and the
  			 * directory component is the cwd */
  			audit_log_d_path(ab, " name=", &context->pwd);
  			break;
  		default:
  			/* log the name's directory component */
  			audit_log_format(ab, " name=");
  			audit_log_n_untrustedstring(ab, n->name->name,
  						    n->name_len);
  		}
  	} else
  		audit_log_format(ab, " name=(null)");
  
  	if (n->ino != (unsigned long)-1) {
  		audit_log_format(ab, " inode=%lu"
  				 " dev=%02x:%02x mode=%#ho"
  				 " ouid=%u ogid=%u rdev=%02x:%02x",
  				 n->ino,
  				 MAJOR(n->dev),
  				 MINOR(n->dev),
  				 n->mode,
  				 from_kuid(&init_user_ns, n->uid),
  				 from_kgid(&init_user_ns, n->gid),
  				 MAJOR(n->rdev),
  				 MINOR(n->rdev));
  	}
  	if (n->osid != 0) {
  		char *ctx = NULL;
  		u32 len;
  		if (security_secid_to_secctx(
  			n->osid, &ctx, &len)) {
  			audit_log_format(ab, " osid=%u", n->osid);
  			if (call_panic)
  				*call_panic = 2;
  		} else {
  			audit_log_format(ab, " obj=%s", ctx);
  			security_release_secctx(ctx, len);
  		}
  	}
  
  	audit_log_fcaps(ab, n);
  	audit_log_end(ab);
  }
  
  int audit_log_task_context(struct audit_buffer *ab)
  {
  	char *ctx = NULL;
  	unsigned len;
  	int error;
  	u32 sid;
  
  	security_task_getsecid(current, &sid);
  	if (!sid)
  		return 0;
  
  	error = security_secid_to_secctx(sid, &ctx, &len);
  	if (error) {
  		if (error != -EINVAL)
  			goto error_path;
  		return 0;
  	}
  
  	audit_log_format(ab, " subj=%s", ctx);
  	security_release_secctx(ctx, len);
  	return 0;
  
  error_path:
  	audit_panic("error in audit_log_task_context");
  	return error;
  }
  EXPORT_SYMBOL(audit_log_task_context);
  
  void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
  {
  	const struct cred *cred;
  	char name[sizeof(tsk->comm)];
  	struct mm_struct *mm = tsk->mm;
  	char *tty;
  
  	if (!ab)
  		return;
  
  	/* tsk == current */
  	cred = current_cred();
  
  	spin_lock_irq(&tsk->sighand->siglock);
  	if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
  		tty = tsk->signal->tty->name;
  	else
  		tty = "(none)";
  	spin_unlock_irq(&tsk->sighand->siglock);
  
  	audit_log_format(ab,
  			 " ppid=%ld pid=%d auid=%u uid=%u gid=%u"
  			 " euid=%u suid=%u fsuid=%u"
  			 " egid=%u sgid=%u fsgid=%u ses=%u tty=%s",
  			 sys_getppid(),
  			 tsk->pid,
  			 from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
  			 from_kuid(&init_user_ns, cred->uid),
  			 from_kgid(&init_user_ns, cred->gid),
  			 from_kuid(&init_user_ns, cred->euid),
  			 from_kuid(&init_user_ns, cred->suid),
  			 from_kuid(&init_user_ns, cred->fsuid),
  			 from_kgid(&init_user_ns, cred->egid),
  			 from_kgid(&init_user_ns, cred->sgid),
  			 from_kgid(&init_user_ns, cred->fsgid),
  			 audit_get_sessionid(tsk), tty);
  
  	get_task_comm(name, tsk);
  	audit_log_format(ab, " comm=");
  	audit_log_untrustedstring(ab, name);
  
  	if (mm) {
  		down_read(&mm->mmap_sem);
  		if (mm->exe_file)
  			audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
  		up_read(&mm->mmap_sem);
  	}
  	audit_log_task_context(ab);
  }
  EXPORT_SYMBOL(audit_log_task_info);

  /**

   * audit_log_link_denied - report a link restriction denial
   * @operation: specific link opreation
   * @link: the path that triggered the restriction
   */
  void audit_log_link_denied(const char *operation, struct path *link)
  {
  	struct audit_buffer *ab;

  	struct audit_names *name;
  
  	name = kzalloc(sizeof(*name), GFP_NOFS);
  	if (!name)
  		return;

  	/* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */

  	ab = audit_log_start(current->audit_context, GFP_KERNEL,
  			     AUDIT_ANOM_LINK);

  	if (!ab)

  		goto out;
  	audit_log_format(ab, "op=%s", operation);
  	audit_log_task_info(ab, current);
  	audit_log_format(ab, " res=0");

  	audit_log_end(ab);

  
  	/* Generate AUDIT_PATH record with object. */
  	name->type = AUDIT_TYPE_NORMAL;
  	audit_copy_inode(name, link->dentry, link->dentry->d_inode);
  	audit_log_name(current->audit_context, name, link, 0, NULL);
  out:
  	kfree(name);

  }
  
  /**

   * 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_HDRLEN;

  		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);