Initial import

1 files changed, 2036 insertions, 0 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
new file mode 100644
index 000000000..1c13e4267
--- /dev/null
+++ b/kernel/audit.c
@@ -0,0 +1,2036 @@
+/* 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/
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/file.h>
+#include <linux/init.h>
+#include <linux/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 <linux/freezer.h>
+#include <linux/tty.h>
+#include <linux/pid_namespace.h>
+#include <net/netns/generic.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
+u32		audit_enabled;
+u32		audit_ever_enabled;
+
+EXPORT_SYMBOL_GPL(audit_enabled);
+
+/* Default state when kernel boots without any parameters. */
+static u32	audit_default;
+
+/* If auditing cannot proceed, audit_failure selects what happens. */
+static u32	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 __u32	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 u32	audit_rate_limit;
+
+/* Number of outstanding audit_buffers allowed.
+ * When set to zero, this means unlimited. */
+static u32	audit_backlog_limit = 64;
+#define AUDIT_BACKLOG_WAIT_TIME (60 * HZ)
+static u32	audit_backlog_wait_time_master = AUDIT_BACKLOG_WAIT_TIME;
+static u32	audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
+static u32	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;
+static int audit_net_id;
+
+/* 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);
+
+static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
+				   .mask = -1,
+				   .features = 0,
+				   .lock = 0,};
+
+static char *audit_feature_names[2] = {
+	"only_unset_loginuid",
+	"loginuid_immutable",
+};
+
+
+/* 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 {
+	__u32 portid;
+	struct net *net;
+	struct sk_buff *skb;
+};
+
+static void audit_set_portid(struct audit_buffer *ab, __u32 portid)
+{
+	if (ab) {
+		struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
+		nlh->nlmsg_pid = portid;
+	}
+}
+
+void audit_panic(const char *message)
+{
+	switch (audit_failure) {
+	case AUDIT_FAIL_SILENT:
+		break;
+	case AUDIT_FAIL_PRINTK:
+		if (printk_ratelimit())
+			pr_err("%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())
+			pr_warn("audit_lost=%u audit_rate_limit=%u audit_backlog_limit=%u\n",
+				atomic_read(&audit_lost),
+				audit_rate_limit,
+				audit_backlog_limit);
+		audit_panic(message);
+	}
+}
+
+static int audit_log_config_change(char *function_name, u32 new, u32 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=%u old=%u", 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, u32 *to_change, u32 new)
+{
+	int allow_changes, rc = 0;
+	u32 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(u32 limit)
+{
+	return audit_do_config_change("audit_rate_limit", &audit_rate_limit, limit);
+}
+
+static int audit_set_backlog_limit(u32 limit)
+{
+	return audit_do_config_change("audit_backlog_limit", &audit_backlog_limit, limit);
+}
+
+static int audit_set_backlog_wait_time(u32 timeout)
+{
+	return audit_do_config_change("audit_backlog_wait_time",
+				      &audit_backlog_wait_time_master, timeout);
+}
+
+static int audit_set_enabled(u32 state)
+{
+	int rc;
+	if (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(u32 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 &&
+	    (!audit_backlog_limit ||
+	     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())
+			pr_notice("type=%d %s\n", 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 */
+		if (audit_pid) {
+			pr_err("*NO* daemon at audit_pid=%d\n", audit_pid);
+			audit_log_lost("auditd disappeared");
+			audit_pid = 0;
+			audit_sock = NULL;
+		}
+		/* 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);
+}
+
+/*
+ * kauditd_send_multicast_skb - send the skb to multicast userspace listeners
+ *
+ * This function doesn't consume an skb as might be expected since it has to
+ * copy it anyways.
+ */
+static void kauditd_send_multicast_skb(struct sk_buff *skb, gfp_t gfp_mask)
+{
+	struct sk_buff		*copy;
+	struct audit_net	*aunet = net_generic(&init_net, audit_net_id);
+	struct sock		*sock = aunet->nlsk;
+
+	if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
+		return;
+
+	/*
+	 * The seemingly wasteful skb_copy() rather than bumping the refcount
+	 * using skb_get() is necessary because non-standard mods are made to
+	 * the skb by the original kaudit unicast socket send routine.  The
+	 * existing auditd daemon assumes this breakage.  Fixing this would
+	 * require co-ordinating a change in the established protocol between
+	 * the kaudit kernel subsystem and the auditd userspace code.  There is
+	 * no reason for new multicast clients to continue with this
+	 * non-compliance.
+	 */
+	copy = skb_copy(skb, gfp_mask);
+	if (!copy)
+		return;
+
+	nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, gfp_mask);
+}
+
+/*
+ * 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;
+
+		flush_hold_queue();
+
+		skb = skb_dequeue(&audit_skb_queue);
+
+		if (skb) {
+			if (skb_queue_len(&audit_skb_queue) <= audit_backlog_limit)
+				wake_up(&audit_backlog_wait);
+			if (audit_pid)
+				kauditd_send_skb(skb);
+			else
+				audit_printk_skb(skb);
+			continue;
+		}
+
+		wait_event_freezable(kauditd_wait, skb_queue_len(&audit_skb_queue));
+	}
+	return 0;
+}
+
+int audit_send_list(void *_dest)
+{
+	struct audit_netlink_list *dest = _dest;
+	struct sk_buff *skb;
+	struct net *net = dest->net;
+	struct audit_net *aunet = net_generic(net, audit_net_id);
+
+	/* 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(aunet->nlsk, skb, dest->portid, 0);
+
+	put_net(net);
+	kfree(dest);
+
+	return 0;
+}
+
+struct sk_buff *audit_make_reply(__u32 portid, 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, portid, 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;
+	struct net *net = reply->net;
+	struct audit_net *aunet = net_generic(net, audit_net_id);
+
+	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(aunet->nlsk , reply->skb, reply->portid, 0);
+	put_net(net);
+	kfree(reply);
+	return 0;
+}
+/**
+ * audit_send_reply - send an audit reply message via netlink
+ * @request_skb: skb of request we are replying to (used to target the reply)
+ * @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 port id.
+ * No failure notifications.
+ */
+static void audit_send_reply(struct sk_buff *request_skb, int seq, int type, int done,
+			     int multi, const void *payload, int size)
+{
+	u32 portid = NETLINK_CB(request_skb).portid;
+	struct net *net = sock_net(NETLINK_CB(request_skb).sk);
+	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(portid, seq, type, done, multi, payload, size);
+	if (!skb)
+		goto out;
+
+	reply->net = get_net(net);
+	reply->portid = portid;
+	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 initial user namespace for now. */
+	/*
+	 * We return ECONNREFUSED because it tricks userspace into thinking
+	 * that audit was not configured into the kernel.  Lots of users
+	 * configure their PAM stack (because that's what the distro does)
+	 * to reject login if unable to send messages to audit.  If we return
+	 * ECONNREFUSED the PAM stack thinks the kernel does not have audit
+	 * configured in and will let login proceed.  If we return EPERM
+	 * userspace will reject all logins.  This should be removed when we
+	 * support non init namespaces!!
+	 */
+	if (current_user_ns() != &init_user_ns)
+		return -ECONNREFUSED;
+
+	switch (msg_type) {
+	case AUDIT_LIST:
+	case AUDIT_ADD:
+	case AUDIT_DEL:
+		return -EOPNOTSUPP;
+	case AUDIT_GET:
+	case AUDIT_SET:
+	case AUDIT_GET_FEATURE:
+	case AUDIT_SET_FEATURE:
+	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:
+		/* Only support auditd and auditctl in initial pid namespace
+		 * for now. */
+		if (task_active_pid_ns(current) != &init_pid_ns)
+			return -EPERM;
+
+		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());
+	pid_t pid = task_tgid_nr(current);
+
+	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", pid, uid);
+	audit_log_session_info(*ab);
+	audit_log_task_context(*ab);
+
+	return rc;
+}
+
+int is_audit_feature_set(int i)
+{
+	return af.features & AUDIT_FEATURE_TO_MASK(i);
+}
+
+
+static int audit_get_feature(struct sk_buff *skb)
+{
+	u32 seq;
+
+	seq = nlmsg_hdr(skb)->nlmsg_seq;
+
+	audit_send_reply(skb, seq, AUDIT_GET_FEATURE, 0, 0, &af, sizeof(af));
+
+	return 0;
+}
+
+static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
+				     u32 old_lock, u32 new_lock, int res)
+{
+	struct audit_buffer *ab;
+
+	if (audit_enabled == AUDIT_OFF)
+		return;
+
+	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
+	audit_log_task_info(ab, current);
+	audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
+			 audit_feature_names[which], !!old_feature, !!new_feature,
+			 !!old_lock, !!new_lock, res);
+	audit_log_end(ab);
+}
+
+static int audit_set_feature(struct sk_buff *skb)
+{
+	struct audit_features *uaf;
+	int i;
+
+	BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > ARRAY_SIZE(audit_feature_names));
+	uaf = nlmsg_data(nlmsg_hdr(skb));
+
+	/* if there is ever a version 2 we should handle that here */
+
+	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
+		u32 feature = AUDIT_FEATURE_TO_MASK(i);
+		u32 old_feature, new_feature, old_lock, new_lock;
+
+		/* if we are not changing this feature, move along */
+		if (!(feature & uaf->mask))
+			continue;
+
+		old_feature = af.features & feature;
+		new_feature = uaf->features & feature;
+		new_lock = (uaf->lock | af.lock) & feature;
+		old_lock = af.lock & feature;
+
+		/* are we changing a locked feature? */
+		if (old_lock && (new_feature != old_feature)) {
+			audit_log_feature_change(i, old_feature, new_feature,
+						 old_lock, new_lock, 0);
+			return -EPERM;
+		}
+	}
+	/* nothing invalid, do the changes */
+	for (i = 0; i <= AUDIT_LAST_FEATURE; i++) {
+		u32 feature = AUDIT_FEATURE_TO_MASK(i);
+		u32 old_feature, new_feature, old_lock, new_lock;
+
+		/* if we are not changing this feature, move along */
+		if (!(feature & uaf->mask))
+			continue;
+
+		old_feature = af.features & feature;
+		new_feature = uaf->features & feature;
+		old_lock = af.lock & feature;
+		new_lock = (uaf->lock | af.lock) & feature;
+
+		if (new_feature != old_feature)
+			audit_log_feature_change(i, old_feature, new_feature,
+						 old_lock, new_lock, 1);
+
+		if (new_feature)
+			af.features |= feature;
+		else
+			af.features &= ~feature;
+		af.lock |= new_lock;
+	}
+
+	return 0;
+}
+
+static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+{
+	u32			seq;
+	void			*data;
+	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: {
+		struct audit_status	s;
+		memset(&s, 0, sizeof(s));
+		s.enabled		= audit_enabled;
+		s.failure		= audit_failure;
+		s.pid			= audit_pid;
+		s.rate_limit		= audit_rate_limit;
+		s.backlog_limit		= audit_backlog_limit;
+		s.lost			= atomic_read(&audit_lost);
+		s.backlog		= skb_queue_len(&audit_skb_queue);
+		s.feature_bitmap	= AUDIT_FEATURE_BITMAP_ALL;
+		s.backlog_wait_time	= audit_backlog_wait_time_master;
+		audit_send_reply(skb, seq, AUDIT_GET, 0, 0, &s, sizeof(s));
+		break;
+	}
+	case AUDIT_SET: {
+		struct audit_status	s;
+		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.mask & AUDIT_STATUS_ENABLED) {
+			err = audit_set_enabled(s.enabled);
+			if (err < 0)
+				return err;
+		}
+		if (s.mask & AUDIT_STATUS_FAILURE) {
+			err = audit_set_failure(s.failure);
+			if (err < 0)
+				return err;
+		}
+		if (s.mask & AUDIT_STATUS_PID) {
+			int new_pid = s.pid;
+
+			if ((!new_pid) && (task_tgid_vnr(current) != audit_pid))
+				return -EACCES;
+			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;
+			audit_sock = skb->sk;
+		}
+		if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
+			err = audit_set_rate_limit(s.rate_limit);
+			if (err < 0)
+				return err;
+		}
+		if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT) {
+			err = audit_set_backlog_limit(s.backlog_limit);
+			if (err < 0)
+				return err;
+		}
+		if (s.mask & AUDIT_STATUS_BACKLOG_WAIT_TIME) {
+			if (sizeof(s) > (size_t)nlh->nlmsg_len)
+				return -EINVAL;
+			if (s.backlog_wait_time > 10*AUDIT_BACKLOG_WAIT_TIME)
+				return -EINVAL;
+			err = audit_set_backlog_wait_time(s.backlog_wait_time);
+			if (err < 0)
+				return err;
+		}
+		break;
+	}
+	case AUDIT_GET_FEATURE:
+		err = audit_get_feature(skb);
+		if (err)
+			return err;
+		break;
+	case AUDIT_SET_FEATURE:
+		err = audit_set_feature(skb);
+		if (err)
+			return err;
+		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) { /* match or error */
+			err = 0;
+			if (msg_type == AUDIT_USER_TTY) {
+				err = tty_audit_push_current();
+				if (err)
+					break;
+			}
+			mutex_unlock(&audit_cmd_mutex);
+			audit_log_common_recv_msg(&ab, msg_type);
+			if (msg_type != AUDIT_USER_TTY)
+				audit_log_format(ab, " msg='%.*s'",
+						 AUDIT_MESSAGE_TEXT_MAX,
+						 (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_portid(ab, NETLINK_CB(skb).portid);
+			audit_log_end(ab);
+			mutex_lock(&audit_cmd_mutex);
+		}
+		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;
+		}
+		err = audit_rule_change(msg_type, NETLINK_CB(skb).portid,
+					   seq, data, nlmsg_len(nlh));
+		break;
+	case AUDIT_LIST_RULES:
+		err = audit_list_rules_send(skb, seq);
+		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(skb, 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;
+		s.log_passwd = tsk->signal->audit_tty_log_passwd;
+		spin_unlock(&tsk->sighand->siglock);
+
+		audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
+		break;
+	}
+	case AUDIT_TTY_SET: {
+		struct audit_tty_status s, old;
+		struct task_struct *tsk = current;
+		struct audit_buffer	*ab;
+
+		memset(&s, 0, sizeof(s));
+		/* guard against past and future API changes */
+		memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
+		/* check if new data is valid */
+		if ((s.enabled != 0 && s.enabled != 1) ||
+		    (s.log_passwd != 0 && s.log_passwd != 1))
+			err = -EINVAL;
+
+		spin_lock(&tsk->sighand->siglock);
+		old.enabled = tsk->signal->audit_tty;
+		old.log_passwd = tsk->signal->audit_tty_log_passwd;
+		if (!err) {
+			tsk->signal->audit_tty = s.enabled;
+			tsk->signal->audit_tty_log_passwd = s.log_passwd;
+		}
+		spin_unlock(&tsk->sighand->siglock);
+
+		audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
+		audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"
+				 " old-log_passwd=%d new-log_passwd=%d res=%d",
+				 old.enabled, s.enabled, old.log_passwd,
+				 s.log_passwd, !err);
+		audit_log_end(ab);
+		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);
+}
+
+/* Run custom bind function on netlink socket group connect or bind requests. */
+static int audit_bind(struct net *net, int group)
+{
+	if (!capable(CAP_AUDIT_READ))
+		return -EPERM;
+
+	return 0;
+}
+
+static int __net_init audit_net_init(struct net *net)
+{
+	struct netlink_kernel_cfg cfg = {
+		.input	= audit_receive,
+		.bind	= audit_bind,
+		.flags	= NL_CFG_F_NONROOT_RECV,
+		.groups	= AUDIT_NLGRP_MAX,
+	};
+
+	struct audit_net *aunet = net_generic(net, audit_net_id);
+
+	aunet->nlsk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg);
+	if (aunet->nlsk == NULL) {
+		audit_panic("cannot initialize netlink socket in namespace");
+		return -ENOMEM;
+	}
+	aunet->nlsk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
+	return 0;
+}
+
+static void __net_exit audit_net_exit(struct net *net)
+{
+	struct audit_net *aunet = net_generic(net, audit_net_id);
+	struct sock *sock = aunet->nlsk;
+	if (sock == audit_sock) {
+		audit_pid = 0;
+		audit_sock = NULL;
+	}
+
+	RCU_INIT_POINTER(aunet->nlsk, NULL);
+	synchronize_net();
+	netlink_kernel_release(sock);
+}
+
+static struct pernet_operations audit_net_ops __net_initdata = {
+	.init = audit_net_init,
+	.exit = audit_net_exit,
+	.id = &audit_net_id,
+	.size = sizeof(struct audit_net),
+};
+
+/* Initialize audit support at boot time. */
+static int __init audit_init(void)
+{
+	int i;
+
+	if (audit_initialized == AUDIT_DISABLED)
+		return 0;
+
+	pr_info("initializing netlink subsys (%s)\n",
+		audit_default ? "enabled" : "disabled");
+	register_pernet_subsys(&audit_net_ops);
+
+	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;
+
+	pr_info("%s\n", audit_default ?
+		"enabled (after initialization)" : "disabled (until reboot)");
+
+	return 1;
+}
+__setup("audit=", audit_enable);
+
+/* Process kernel command-line parameter at boot time.
+ * audit_backlog_limit=<n> */
+static int __init audit_backlog_limit_set(char *str)
+{
+	u32 audit_backlog_limit_arg;
+
+	pr_info("audit_backlog_limit: ");
+	if (kstrtouint(str, 0, &audit_backlog_limit_arg)) {
+		pr_cont("using default of %u, unable to parse %s\n",
+			audit_backlog_limit, str);
+		return 1;
+	}
+
+	audit_backlog_limit = audit_backlog_limit_arg;
+	pr_cont("%d\n", audit_backlog_limit);
+
+	return 1;
+}
+__setup("audit_backlog_limit=", audit_backlog_limit_set);
+
+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 atomic_t serial = ATOMIC_INIT(0);
+
+	return atomic_add_return(1, &serial);
+}
+
+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 long wait_for_auditd(long sleep_time)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	add_wait_queue_exclusive(&audit_backlog_wait, &wait);
+
+	if (audit_backlog_limit &&
+	    skb_queue_len(&audit_skb_queue) > audit_backlog_limit)
+		sleep_time = schedule_timeout(sleep_time);
+
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&audit_backlog_wait, &wait);
+
+	return sleep_time;
+}
+
+/**
+ * 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 = 5; /* Allow atomic callers to go up to five
+			    entries over the normal backlog limit */
+	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) {
+		if (audit_pid && audit_pid == current->pid)
+			gfp_mask &= ~__GFP_WAIT;
+		else
+			reserve = 0;
+	}
+
+	while (audit_backlog_limit
+	       && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
+		if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
+			long sleep_time;
+
+			sleep_time = timeout_start + audit_backlog_wait_time - jiffies;
+			if (sleep_time > 0) {
+				sleep_time = wait_for_auditd(sleep_time);
+				if (sleep_time > 0)
+					continue;
+			}
+		}
+		if (audit_rate_check() && printk_ratelimit())
+			pr_warn("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;
+	}
+
+	if (!reserve)
+		audit_backlog_wait_time = audit_backlog_wait_time_master;
+
+	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;
+
+	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_byte_pack_upper(ptr, buf[i]);
+	*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)
+{
+	unsigned int 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[CAP_LAST_U32 - i]);
+	}
+}
+
+static 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);
+		}
+	}
+
+	/* log the audit_names record type */
+	audit_log_format(ab, " nametype=");
+	switch(n->type) {
+	case AUDIT_TYPE_NORMAL:
+		audit_log_format(ab, "NORMAL");
+		break;
+	case AUDIT_TYPE_PARENT:
+		audit_log_format(ab, "PARENT");
+		break;
+	case AUDIT_TYPE_CHILD_DELETE:
+		audit_log_format(ab, "DELETE");
+		break;
+	case AUDIT_TYPE_CHILD_CREATE:
+		audit_log_format(ab, "CREATE");
+		break;
+	default:
+		audit_log_format(ab, "UNKNOWN");
+		break;
+	}
+
+	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_d_path_exe(struct audit_buffer *ab,
+			  struct mm_struct *mm)
+{
+	struct file *exe_file;
+
+	if (!mm)
+		goto out_null;
+
+	exe_file = get_mm_exe_file(mm);
+	if (!exe_file)
+		goto out_null;
+
+	audit_log_d_path(ab, " exe=", &exe_file->f_path);
+	fput(exe_file);
+	return;
+out_null:
+	audit_log_format(ab, " exe=(null)");
+}
+
+void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
+{
+	const struct cred *cred;
+	char comm[sizeof(tsk->comm)];
+	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=%d pid=%d auid=%u uid=%u gid=%u"
+			 " euid=%u suid=%u fsuid=%u"
+			 " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
+			 task_ppid_nr(tsk),
+			 task_pid_nr(tsk),
+			 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),
+			 tty, audit_get_sessionid(tsk));
+
+	audit_log_format(ab, " comm=");
+	audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
+
+	audit_log_d_path_exe(ab, tsk->mm);
+	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, d_backing_inode(link->dentry));
+	audit_log_name(current->audit_context, name, link, 0, NULL);
+out:
+	kfree(name);
+}
+
+/**
+ * audit_log_end - end one audit record
+ * @ab: the audit_buffer
+ *
+ * netlink_unicast() cannot be called inside an irq context because it blocks
+ * (last arg, flags, is not set to MSG_DONTWAIT), 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;
+		kauditd_send_multicast_skb(ab->skb, ab->gfp_mask);
+
+		/*
+		 * The original kaudit unicast socket sends up messages with
+		 * nlmsg_len set to the payload length rather than the entire
+		 * message length.  This breaks the standard set by netlink.
+		 * The existing auditd daemon assumes this breakage.  Fixing
+		 * this would require co-ordinating a change in the established
+		 * protocol between the kaudit kernel subsystem and the auditd
+		 * userspace code.
+		 */
+		nlh->nlmsg_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);