Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 839 insertions, 0 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
new file mode 100644
index 00000000000..0f84dd7af2c
--- /dev/null
+++ b/kernel/audit.c
@@ -0,0 +1,839 @@
+/* audit.c -- Auditing support -*- linux-c -*-
+ * Gateway between the kernel (e.g., selinux) and the user-space audit daemon.
+ * System-call specific features have moved to auditsc.c
+ *
+ * Copyright 2003-2004 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 SELinux.
+ *	  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/faith/audit/
+ */
+
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <asm/types.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include <linux/audit.h>
+
+#include <net/sock.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+
+/* No auditing will take place until audit_initialized != 0.
+ * (Initialization happens after skb_init is called.) */
+static int	audit_initialized;
+
+/* No syscall auditing will take place unless audit_enabled != 0. */
+int		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 (non-zero) pid. */
+static int	audit_pid;
+
+/* If audit_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 atomic_t	audit_backlog	    = ATOMIC_INIT(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;
+
+/* There are two lists of audit buffers.  The txlist contains audit
+ * buffers that cannot be sent immediately to the netlink device because
+ * we are in an irq context (these are sent later in a tasklet).
+ *
+ * The second list 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_txlist_lock);
+static DEFINE_SPINLOCK(audit_freelist_lock);
+static int	   audit_freelist_count = 0;
+static LIST_HEAD(audit_txlist);
+static LIST_HEAD(audit_freelist);
+
+/* There are three lists of rules -- one to search at task creation
+ * time, one to search at syscall entry time, and another to search at
+ * syscall exit time. */
+static LIST_HEAD(audit_tsklist);
+static LIST_HEAD(audit_entlist);
+static LIST_HEAD(audit_extlist);
+
+/* The netlink socket is only to be read by 1 CPU, which lets us assume
+ * that list additions and deletions never happen simultaneiously in
+ * auditsc.c */
+static DECLARE_MUTEX(audit_netlink_sem);
+
+/* 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_head  sklist;	/* formatted skbs ready to send */
+	struct audit_context *ctx;	/* NULL or associated context */
+	int		     len;	/* used area of tmp */
+	char		     tmp[AUDIT_BUFSIZ];
+
+				/* Pointer to header and contents */
+	struct nlmsghdr      *nlh;
+	int		     total;
+	int		     type;
+	int		     pid;
+	int		     count; /* Times requeued */
+};
+
+void audit_set_type(struct audit_buffer *ab, int type)
+{
+	ab->type = type;
+}
+
+struct audit_entry {
+	struct list_head  list;
+	struct audit_rule rule;
+};
+
+static void audit_log_end_irq(struct audit_buffer *ab);
+static void audit_log_end_fast(struct audit_buffer *ab);
+
+static void audit_panic(const char *message)
+{
+	switch (audit_failure)
+	{
+	case AUDIT_FAIL_SILENT:
+		break;
+	case AUDIT_FAIL_PRINTK:
+		printk(KERN_ERR "audit: %s\n", message);
+		break;
+	case AUDIT_FAIL_PANIC:
+		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;
+}
+
+/* Emit at least 1 message per second, even if audit_rate_check is
+ * throttling. */
+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) {
+		printk(KERN_WARNING
+		       "audit: audit_lost=%d audit_backlog=%d"
+		       " audit_rate_limit=%d audit_backlog_limit=%d\n",
+		       atomic_read(&audit_lost),
+		       atomic_read(&audit_backlog),
+		       audit_rate_limit,
+		       audit_backlog_limit);
+		audit_panic(message);
+	}
+
+}
+
+static int audit_set_rate_limit(int limit)
+{
+	int old		 = audit_rate_limit;
+	audit_rate_limit = limit;
+	audit_log(current->audit_context, "audit_rate_limit=%d old=%d",
+		  audit_rate_limit, old);
+	return old;
+}
+
+static int audit_set_backlog_limit(int limit)
+{
+	int old		 = audit_backlog_limit;
+	audit_backlog_limit = limit;
+	audit_log(current->audit_context, "audit_backlog_limit=%d old=%d",
+		  audit_backlog_limit, old);
+	return old;
+}
+
+static int audit_set_enabled(int state)
+{
+	int old		 = audit_enabled;
+	if (state != 0 && state != 1)
+		return -EINVAL;
+	audit_enabled = state;
+	audit_log(current->audit_context, "audit_enabled=%d old=%d",
+		  audit_enabled, old);
+	return old;
+}
+
+static int audit_set_failure(int state)
+{
+	int old		 = audit_failure;
+	if (state != AUDIT_FAIL_SILENT
+	    && state != AUDIT_FAIL_PRINTK
+	    && state != AUDIT_FAIL_PANIC)
+		return -EINVAL;
+	audit_failure = state;
+	audit_log(current->audit_context, "audit_failure=%d old=%d",
+		  audit_failure, old);
+	return old;
+}
+
+#ifdef CONFIG_NET
+void audit_send_reply(int pid, int seq, int type, int done, int multi,
+		      void *payload, int size)
+{
+	struct sk_buff	*skb;
+	struct nlmsghdr	*nlh;
+	int		len = NLMSG_SPACE(size);
+	void		*data;
+	int		flags = multi ? NLM_F_MULTI : 0;
+	int		t     = done  ? NLMSG_DONE  : type;
+
+	skb = alloc_skb(len, GFP_KERNEL);
+	if (!skb)
+		goto nlmsg_failure;
+
+	nlh		 = NLMSG_PUT(skb, pid, seq, t, len - sizeof(*nlh));
+	nlh->nlmsg_flags = flags;
+	data		 = NLMSG_DATA(nlh);
+	memcpy(data, payload, size);
+	netlink_unicast(audit_sock, skb, pid, MSG_DONTWAIT);
+	return;
+
+nlmsg_failure:			/* Used by NLMSG_PUT */
+	if (skb)
+		kfree_skb(skb);
+}
+
+/*
+ * Check for appropriate CAP_AUDIT_ capabilities on incoming audit
+ * control messages.
+ */
+static int audit_netlink_ok(kernel_cap_t eff_cap, u16 msg_type)
+{
+	int err = 0;
+
+	switch (msg_type) {
+	case AUDIT_GET:
+	case AUDIT_LIST:
+	case AUDIT_SET:
+	case AUDIT_ADD:
+	case AUDIT_DEL:
+		if (!cap_raised(eff_cap, CAP_AUDIT_CONTROL))
+			err = -EPERM;
+		break;
+	case AUDIT_USER:
+		if (!cap_raised(eff_cap, CAP_AUDIT_WRITE))
+			err = -EPERM;
+		break;
+	default:  /* bad msg */
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+{
+	u32			uid, pid, seq;
+	void			*data;
+	struct audit_status	*status_get, status_set;
+	int			err;
+	struct audit_buffer	*ab;
+	u16			msg_type = nlh->nlmsg_type;
+
+	err = audit_netlink_ok(NETLINK_CB(skb).eff_cap, msg_type);
+	if (err)
+		return err;
+
+	pid  = NETLINK_CREDS(skb)->pid;
+	uid  = NETLINK_CREDS(skb)->uid;
+	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	 = atomic_read(&audit_backlog);
+		audit_send_reply(NETLINK_CB(skb).pid, seq, AUDIT_GET, 0, 0,
+				 &status_set, sizeof(status_set));
+		break;
+	case AUDIT_SET:
+		if (nlh->nlmsg_len < sizeof(struct audit_status))
+			return -EINVAL;
+		status_get   = (struct audit_status *)data;
+		if (status_get->mask & AUDIT_STATUS_ENABLED) {
+			err = audit_set_enabled(status_get->enabled);
+			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 old   = audit_pid;
+			audit_pid = status_get->pid;
+			audit_log(current->audit_context,
+				  "audit_pid=%d old=%d", audit_pid, old);
+		}
+		if (status_get->mask & AUDIT_STATUS_RATE_LIMIT)
+			audit_set_rate_limit(status_get->rate_limit);
+		if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
+			audit_set_backlog_limit(status_get->backlog_limit);
+		break;
+	case AUDIT_USER:
+		ab = audit_log_start(NULL);
+		if (!ab)
+			break;	/* audit_panic has been called */
+		audit_log_format(ab,
+				 "user pid=%d uid=%d length=%d msg='%.1024s'",
+				 pid, uid,
+				 (int)(nlh->nlmsg_len
+				       - ((char *)data - (char *)nlh)),
+				 (char *)data);
+		ab->type = AUDIT_USER;
+		ab->pid  = pid;
+		audit_log_end(ab);
+		break;
+	case AUDIT_ADD:
+	case AUDIT_DEL:
+		if (nlh->nlmsg_len < sizeof(struct audit_rule))
+			return -EINVAL;
+		/* fallthrough */
+	case AUDIT_LIST:
+#ifdef CONFIG_AUDITSYSCALL
+		err = audit_receive_filter(nlh->nlmsg_type, NETLINK_CB(skb).pid,
+					   uid, seq, data);
+#else
+		err = -EOPNOTSUPP;
+#endif
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	return err < 0 ? err : 0;
+}
+
+/* Get message from skb (based on rtnetlink_rcv_skb).  Each message is
+ * processed by audit_receive_msg.  Malformed skbs with wrong length are
+ * discarded silently.  */
+static int audit_receive_skb(struct sk_buff *skb)
+{
+	int		err;
+	struct nlmsghdr	*nlh;
+	u32		rlen;
+
+	while (skb->len >= NLMSG_SPACE(0)) {
+		nlh = (struct nlmsghdr *)skb->data;
+		if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
+			return 0;
+		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
+		if (rlen > skb->len)
+			rlen = skb->len;
+		if ((err = audit_receive_msg(skb, nlh))) {
+			netlink_ack(skb, nlh, err);
+		} else if (nlh->nlmsg_flags & NLM_F_ACK)
+			netlink_ack(skb, nlh, 0);
+		skb_pull(skb, rlen);
+	}
+	return 0;
+}
+
+/* Receive messages from netlink socket. */
+static void audit_receive(struct sock *sk, int length)
+{
+	struct sk_buff  *skb;
+
+	if (down_trylock(&audit_netlink_sem))
+		return;
+
+				/* FIXME: this must not cause starvation */
+	while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
+		if (audit_receive_skb(skb) && skb->len)
+			skb_queue_head(&sk->sk_receive_queue, skb);
+		else
+			kfree_skb(skb);
+	}
+	up(&audit_netlink_sem);
+}
+
+/* Move data from tmp buffer into an skb.  This is an extra copy, and
+ * that is unfortunate.  However, the copy will only occur when a record
+ * is being written to user space, which is already a high-overhead
+ * operation.  (Elimination of the copy is possible, for example, by
+ * writing directly into a pre-allocated skb, at the cost of wasting
+ * memory. */
+static void audit_log_move(struct audit_buffer *ab)
+{
+	struct sk_buff	*skb;
+	char		*start;
+	int		extra = ab->nlh ? 0 : NLMSG_SPACE(0);
+
+	/* possible resubmission */
+	if (ab->len == 0)
+		return;
+
+	skb = skb_peek(&ab->sklist);
+	if (!skb || skb_tailroom(skb) <= ab->len + extra) {
+		skb = alloc_skb(2 * ab->len + extra, GFP_ATOMIC);
+		if (!skb) {
+			ab->len = 0; /* Lose information in ab->tmp */
+			audit_log_lost("out of memory in audit_log_move");
+			return;
+		}
+		__skb_queue_tail(&ab->sklist, skb);
+		if (!ab->nlh)
+			ab->nlh = (struct nlmsghdr *)skb_put(skb,
+							     NLMSG_SPACE(0));
+	}
+	start = skb_put(skb, ab->len);
+	memcpy(start, ab->tmp, ab->len);
+	ab->len = 0;
+}
+
+/* Iterate over the skbuff in the audit_buffer, sending their contents
+ * to user space. */
+static inline int audit_log_drain(struct audit_buffer *ab)
+{
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&ab->sklist))) {
+		int retval = 0;
+
+		if (audit_pid) {
+			if (ab->nlh) {
+				ab->nlh->nlmsg_len   = ab->total;
+				ab->nlh->nlmsg_type  = ab->type;
+				ab->nlh->nlmsg_flags = 0;
+				ab->nlh->nlmsg_seq   = 0;
+				ab->nlh->nlmsg_pid   = ab->pid;
+			}
+			skb_get(skb); /* because netlink_* frees */
+			retval = netlink_unicast(audit_sock, skb, audit_pid,
+						 MSG_DONTWAIT);
+		}
+		if (retval == -EAGAIN && ab->count < 5) {
+			++ab->count;
+			skb_queue_tail(&ab->sklist, skb);
+			audit_log_end_irq(ab);
+			return 1;
+		}
+		if (retval < 0) {
+			if (retval == -ECONNREFUSED) {
+				printk(KERN_ERR
+				       "audit: *NO* daemon at audit_pid=%d\n",
+				       audit_pid);
+				audit_pid = 0;
+			} else
+				audit_log_lost("netlink socket too busy");
+		}
+		if (!audit_pid) { /* No daemon */
+			int offset = ab->nlh ? NLMSG_SPACE(0) : 0;
+			int len    = skb->len - offset;
+			printk(KERN_ERR "%*.*s\n",
+			       len, len, skb->data + offset);
+		}
+		kfree_skb(skb);
+		ab->nlh = NULL;
+	}
+	return 0;
+}
+
+/* Initialize audit support at boot time. */
+static int __init audit_init(void)
+{
+	printk(KERN_INFO "audit: initializing netlink socket (%s)\n",
+	       audit_default ? "enabled" : "disabled");
+	audit_sock = netlink_kernel_create(NETLINK_AUDIT, audit_receive);
+	if (!audit_sock)
+		audit_panic("cannot initialize netlink socket");
+
+	audit_initialized = 1;
+	audit_enabled = audit_default;
+	audit_log(NULL, "initialized");
+	return 0;
+}
+
+#else
+/* Without CONFIG_NET, we have no skbuffs.  For now, print what we have
+ * in the buffer. */
+static void audit_log_move(struct audit_buffer *ab)
+{
+	printk(KERN_ERR "%*.*s\n", ab->len, ab->len, ab->tmp);
+	ab->len = 0;
+}
+
+static inline int audit_log_drain(struct audit_buffer *ab)
+{
+	return 0;
+}
+
+/* Initialize audit support at boot time. */
+int __init audit_init(void)
+{
+	printk(KERN_INFO "audit: initializing WITHOUT netlink support\n");
+	audit_sock = NULL;
+	audit_pid  = 0;
+
+	audit_initialized = 1;
+	audit_enabled = audit_default;
+	audit_log(NULL, "initialized");
+	return 0;
+}
+#endif
+
+__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);
+	printk(KERN_INFO "audit: %s%s\n",
+	       audit_default ? "enabled" : "disabled",
+	       audit_initialized ? "" : " (after initialization)");
+	if (audit_initialized)
+		audit_enabled = audit_default;
+	return 0;
+}
+
+__setup("audit=", audit_enable);
+
+
+/* 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. */
+struct audit_buffer *audit_log_start(struct audit_context *ctx)
+{
+	struct audit_buffer	*ab	= NULL;
+	unsigned long		flags;
+	struct timespec		t;
+	int			serial	= 0;
+
+	if (!audit_initialized)
+		return NULL;
+
+	if (audit_backlog_limit
+	    && atomic_read(&audit_backlog) > audit_backlog_limit) {
+		if (audit_rate_check())
+			printk(KERN_WARNING
+			       "audit: audit_backlog=%d > "
+			       "audit_backlog_limit=%d\n",
+			       atomic_read(&audit_backlog),
+			       audit_backlog_limit);
+		audit_log_lost("backlog limit exceeded");
+		return NULL;
+	}
+
+	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_ATOMIC);
+	if (!ab) {
+		audit_log_lost("out of memory in audit_log_start");
+		return NULL;
+	}
+
+	atomic_inc(&audit_backlog);
+	skb_queue_head_init(&ab->sklist);
+
+	ab->ctx   = ctx;
+	ab->len   = 0;
+	ab->nlh   = NULL;
+	ab->total = 0;
+	ab->type  = AUDIT_KERNEL;
+	ab->pid   = 0;
+	ab->count = 0;
+
+#ifdef CONFIG_AUDITSYSCALL
+	if (ab->ctx)
+		audit_get_stamp(ab->ctx, &t, &serial);
+	else
+#endif
+		t = CURRENT_TIME;
+
+	audit_log_format(ab, "audit(%lu.%03lu:%u): ",
+			 t.tv_sec, t.tv_nsec/1000000, serial);
+	return ab;
+}
+
+
+/* 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;
+
+	if (!ab)
+		return;
+
+	avail = sizeof(ab->tmp) - ab->len;
+	if (avail <= 0) {
+		audit_log_move(ab);
+		avail = sizeof(ab->tmp) - ab->len;
+	}
+	len   = vsnprintf(ab->tmp + ab->len, 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. */
+		audit_log_move(ab);
+		avail = sizeof(ab->tmp) - ab->len;
+		len   = vsnprintf(ab->tmp + ab->len, avail, fmt, args);
+	}
+	ab->len   += (len < avail) ? len : avail;
+	ab->total += (len < avail) ? len : avail;
+}
+
+/* Format a message into the audit buffer.  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);
+}
+
+/* This is a helper-function to print the d_path without using a static
+ * buffer or allocating another buffer in addition to the one in
+ * audit_buffer. */
+void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
+		      struct dentry *dentry, struct vfsmount *vfsmnt)
+{
+	char *p;
+	int  len, avail;
+
+	if (prefix) audit_log_format(ab, " %s", prefix);
+
+	if (ab->len > 128)
+		audit_log_move(ab);
+	avail = sizeof(ab->tmp) - ab->len;
+	p = d_path(dentry, vfsmnt, ab->tmp + ab->len, avail);
+	if (IS_ERR(p)) {
+		/* FIXME: can we save some information here? */
+		audit_log_format(ab, "<toolong>");
+	} else {
+				/* path isn't at start of buffer */
+		len	   = (ab->tmp + sizeof(ab->tmp) - 1) - p;
+		memmove(ab->tmp + ab->len, p, len);
+		ab->len   += len;
+		ab->total += len;
+	}
+}
+
+/* Remove queued messages from the audit_txlist and send them to userspace. */
+static void audit_tasklet_handler(unsigned long arg)
+{
+	LIST_HEAD(list);
+	struct audit_buffer *ab;
+	unsigned long	    flags;
+
+	spin_lock_irqsave(&audit_txlist_lock, flags);
+	list_splice_init(&audit_txlist, &list);
+	spin_unlock_irqrestore(&audit_txlist_lock, flags);
+
+	while (!list_empty(&list)) {
+		ab = list_entry(list.next, struct audit_buffer, list);
+		list_del(&ab->list);
+		audit_log_end_fast(ab);
+	}
+}
+
+static DECLARE_TASKLET(audit_tasklet, audit_tasklet_handler, 0);
+
+/* The netlink_* functions cannot be called inside an irq context, so
+ * the audit buffer is places on a queue and a tasklet is scheduled to
+ * remove them from the queue outside the irq context.  May be called in
+ * any context. */
+static void audit_log_end_irq(struct audit_buffer *ab)
+{
+	unsigned long flags;
+
+	if (!ab)
+		return;
+	spin_lock_irqsave(&audit_txlist_lock, flags);
+	list_add_tail(&ab->list, &audit_txlist);
+	spin_unlock_irqrestore(&audit_txlist_lock, flags);
+
+	tasklet_schedule(&audit_tasklet);
+}
+
+/* Send the message in the audit buffer directly to user space.  May not
+ * be called in an irq context. */
+static void audit_log_end_fast(struct audit_buffer *ab)
+{
+	unsigned long flags;
+
+	BUG_ON(in_irq());
+	if (!ab)
+		return;
+	if (!audit_rate_check()) {
+		audit_log_lost("rate limit exceeded");
+	} else {
+		audit_log_move(ab);
+		if (audit_log_drain(ab))
+			return;
+	}
+
+	atomic_dec(&audit_backlog);
+	spin_lock_irqsave(&audit_freelist_lock, flags);
+	if (++audit_freelist_count > AUDIT_MAXFREE)
+		kfree(ab);
+	else
+		list_add(&ab->list, &audit_freelist);
+	spin_unlock_irqrestore(&audit_freelist_lock, flags);
+}
+
+/* Send or queue the message in the audit buffer, depending on the
+ * current context.  (A convenience function that may be called in any
+ * context.) */
+void audit_log_end(struct audit_buffer *ab)
+{
+	if (in_irq())
+		audit_log_end_irq(ab);
+	else
+		audit_log_end_fast(ab);
+}
+
+/* Log an audit record.  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, const char *fmt, ...)
+{
+	struct audit_buffer *ab;
+	va_list args;
+
+	ab = audit_log_start(ctx);
+	if (ab) {
+		va_start(args, fmt);
+		audit_log_vformat(ab, fmt, args);
+		va_end(args);
+		audit_log_end(ab);
+	}
+}