[deliverable/linux.git] / drivers / tty / tty_audit.c

/*
 * Creating audit events from TTY input.
 *
 * Copyright (C) 2007 Red Hat, Inc.  All rights reserved.  This copyrighted
 * material is made available to anyone wishing to use, modify, copy, or
 * redistribute it subject to the terms and conditions of the GNU General
 * Public License v.2.
 *
 * Authors: Miloslav Trmac <mitr@redhat.com>
 */

#include <linux/audit.h>
#include <linux/slab.h>
#include <linux/tty.h>

struct tty_audit_buf {
	atomic_t count;
	struct mutex mutex;	/* Protects all data below */
	int major, minor;	/* The TTY which the data is from */
	unsigned icanon:1;
	size_t valid;
	unsigned char *data;	/* Allocated size N_TTY_BUF_SIZE */
};

static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
						 unsigned icanon)
{
	struct tty_audit_buf *buf;

	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
	if (!buf)
		goto err;
	buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
	if (!buf->data)
		goto err_buf;
	atomic_set(&buf->count, 1);
	mutex_init(&buf->mutex);
	buf->major = major;
	buf->minor = minor;
	buf->icanon = icanon;
	buf->valid = 0;
	return buf;

err_buf:
	kfree(buf);
err:
	return NULL;
}

static void tty_audit_buf_free(struct tty_audit_buf *buf)
{
	WARN_ON(buf->valid != 0);
	kfree(buf->data);
	kfree(buf);
}

static void tty_audit_buf_put(struct tty_audit_buf *buf)
{
	if (atomic_dec_and_test(&buf->count))
		tty_audit_buf_free(buf);
}

static void tty_audit_log(const char *description, struct task_struct *tsk,
			  kuid_t loginuid, unsigned sessionid, int major,
			  int minor, unsigned char *data, size_t size)
{
	struct audit_buffer *ab;

	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
	if (ab) {
		char name[sizeof(tsk->comm)];
		kuid_t uid = task_uid(tsk);

		audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
				 "major=%d minor=%d comm=", description,
				 tsk->pid,
				 from_kuid(&init_user_ns, uid),
				 from_kuid(&init_user_ns, loginuid),
				 sessionid,
				 major, minor);
		get_task_comm(name, tsk);
		audit_log_untrustedstring(ab, name);
		audit_log_format(ab, " data=");
		audit_log_n_hex(ab, data, size);
		audit_log_end(ab);
	}
}

/**
 *	tty_audit_buf_push	-	Push buffered data out
 *
 *	Generate an audit message from the contents of @buf, which is owned by
 *	@tsk with @loginuid.  @buf->mutex must be locked.
 */
static void tty_audit_buf_push(struct task_struct *tsk, kuid_t loginuid,
			       unsigned int sessionid,
			       struct tty_audit_buf *buf)
{
	if (buf->valid == 0)
		return;
	if (audit_enabled == 0) {
		buf->valid = 0;
		return;
	}
	tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
		      buf->data, buf->valid);
	buf->valid = 0;
}

/**
 *	tty_audit_buf_push_current	-	Push buffered data out
 *
 *	Generate an audit message from the contents of @buf, which is owned by
 *	the current task.  @buf->mutex must be locked.
 */
static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
{
	kuid_t auid = audit_get_loginuid(current);
	unsigned int sessionid = audit_get_sessionid(current);
	tty_audit_buf_push(current, auid, sessionid, buf);
}

/**
 *	tty_audit_exit	-	Handle a task exit
 *
 *	Make sure all buffered data is written out and deallocate the buffer.
 *	Only needs to be called if current->signal->tty_audit_buf != %NULL.
 */
void tty_audit_exit(void)
{
	struct tty_audit_buf *buf;

	spin_lock_irq(&current->sighand->siglock);
	buf = current->signal->tty_audit_buf;
	current->signal->tty_audit_buf = NULL;
	spin_unlock_irq(&current->sighand->siglock);
	if (!buf)
		return;

	mutex_lock(&buf->mutex);
	tty_audit_buf_push_current(buf);
	mutex_unlock(&buf->mutex);

	tty_audit_buf_put(buf);
}

/**
 *	tty_audit_fork	-	Copy TTY audit state for a new task
 *
 *	Set up TTY audit state in @sig from current.  @sig needs no locking.
 */
void tty_audit_fork(struct signal_struct *sig)
{
	spin_lock_irq(&current->sighand->siglock);
	sig->audit_tty = current->signal->audit_tty;
	spin_unlock_irq(&current->sighand->siglock);
}

/**
 *	tty_audit_tiocsti	-	Log TIOCSTI
 */
void tty_audit_tiocsti(struct tty_struct *tty, char ch)
{
	struct tty_audit_buf *buf;
	int major, minor, should_audit;

	spin_lock_irq(&current->sighand->siglock);
	should_audit = current->signal->audit_tty;
	buf = current->signal->tty_audit_buf;
	if (buf)
		atomic_inc(&buf->count);
	spin_unlock_irq(&current->sighand->siglock);

	major = tty->driver->major;
	minor = tty->driver->minor_start + tty->index;
	if (buf) {
		mutex_lock(&buf->mutex);
		if (buf->major == major && buf->minor == minor)
			tty_audit_buf_push_current(buf);
		mutex_unlock(&buf->mutex);
		tty_audit_buf_put(buf);
	}

	if (should_audit && audit_enabled) {
		kuid_t auid;
		unsigned int sessionid;

		auid = audit_get_loginuid(current);
		sessionid = audit_get_sessionid(current);
		tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
			      minor, &ch, 1);
	}
}

/**
 * tty_audit_push_task	-	Flush task's pending audit data
 * @tsk:		task pointer
 * @loginuid:		sender login uid
 * @sessionid:		sender session id
 *
 * Called with a ref on @tsk held. Try to lock sighand and get a
 * reference to the tty audit buffer if available.
 * Flush the buffer or return an appropriate error code.
 */
int tty_audit_push_task(struct task_struct *tsk, kuid_t loginuid, u32 sessionid)
{
	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
	unsigned long flags;

	if (!lock_task_sighand(tsk, &flags))
		return -ESRCH;

	if (tsk->signal->audit_tty) {
		buf = tsk->signal->tty_audit_buf;
		if (buf)
			atomic_inc(&buf->count);
	}
	unlock_task_sighand(tsk, &flags);

	/*
	 * Return 0 when signal->audit_tty set
	 * but tsk->signal->tty_audit_buf == NULL.
	 */
	if (!buf || IS_ERR(buf))
		return PTR_ERR(buf);

	mutex_lock(&buf->mutex);
	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
	mutex_unlock(&buf->mutex);

	tty_audit_buf_put(buf);
	return 0;
}

/**
 *	tty_audit_buf_get	-	Get an audit buffer.
 *
 *	Get an audit buffer for @tty, allocate it if necessary.  Return %NULL
 *	if TTY auditing is disabled or out of memory.  Otherwise, return a new
 *	reference to the buffer.
 */
static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty,
		unsigned icanon)
{
	struct tty_audit_buf *buf, *buf2;

	buf = NULL;
	buf2 = NULL;
	spin_lock_irq(&current->sighand->siglock);
	if (likely(!current->signal->audit_tty))
		goto out;
	buf = current->signal->tty_audit_buf;
	if (buf) {
		atomic_inc(&buf->count);
		goto out;
	}
	spin_unlock_irq(&current->sighand->siglock);

	buf2 = tty_audit_buf_alloc(tty->driver->major,
				   tty->driver->minor_start + tty->index,
				   icanon);
	if (buf2 == NULL) {
		audit_log_lost("out of memory in TTY auditing");
		return NULL;
	}

	spin_lock_irq(&current->sighand->siglock);
	if (!current->signal->audit_tty)
		goto out;
	buf = current->signal->tty_audit_buf;
	if (!buf) {
		current->signal->tty_audit_buf = buf2;
		buf = buf2;
		buf2 = NULL;
	}
	atomic_inc(&buf->count);
	/* Fall through */
 out:
	spin_unlock_irq(&current->sighand->siglock);
	if (buf2)
		tty_audit_buf_free(buf2);
	return buf;
}

/**
 *	tty_audit_add_data	-	Add data for TTY auditing.
 *
 *	Audit @data of @size from @tty, if necessary.
 */
void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
			size_t size, unsigned icanon)
{
	struct tty_audit_buf *buf;
	int major, minor;

	if (unlikely(size == 0))
		return;

	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	    && tty->driver->subtype == PTY_TYPE_MASTER)
		return;

	buf = tty_audit_buf_get(tty, icanon);
	if (!buf)
		return;

	mutex_lock(&buf->mutex);
	major = tty->driver->major;
	minor = tty->driver->minor_start + tty->index;
	if (buf->major != major || buf->minor != minor
	    || buf->icanon != icanon) {
		tty_audit_buf_push_current(buf);
		buf->major = major;
		buf->minor = minor;
		buf->icanon = icanon;
	}
	do {
		size_t run;

		run = N_TTY_BUF_SIZE - buf->valid;
		if (run > size)
			run = size;
		memcpy(buf->data + buf->valid, data, run);
		buf->valid += run;
		data += run;
		size -= run;
		if (buf->valid == N_TTY_BUF_SIZE)
			tty_audit_buf_push_current(buf);
	} while (size != 0);
	mutex_unlock(&buf->mutex);
	tty_audit_buf_put(buf);
}

/**
 *	tty_audit_push	-	Push buffered data out
 *
 *	Make sure no audit data is pending for @tty on the current process.
 */
void tty_audit_push(struct tty_struct *tty)
{
	struct tty_audit_buf *buf;

	spin_lock_irq(&current->sighand->siglock);
	if (likely(!current->signal->audit_tty)) {
		spin_unlock_irq(&current->sighand->siglock);
		return;
	}
	buf = current->signal->tty_audit_buf;
	if (buf)
		atomic_inc(&buf->count);
	spin_unlock_irq(&current->sighand->siglock);

	if (buf) {
		int major, minor;

		major = tty->driver->major;
		minor = tty->driver->minor_start + tty->index;
		mutex_lock(&buf->mutex);
		if (buf->major == major && buf->minor == minor)
			tty_audit_buf_push_current(buf);
		mutex_unlock(&buf->mutex);
		tty_audit_buf_put(buf);
	}
}
Commit	Line	Data
522ed776 MT	1	/*
	2	* Creating audit events from TTY input.
	3	*
	4	* Copyright (C) 2007 Red Hat, Inc. All rights reserved. This copyrighted
	5	* material is made available to anyone wishing to use, modify, copy, or
	6	* redistribute it subject to the terms and conditions of the GNU General
	7	* Public License v.2.
	8	*
	9	* Authors: Miloslav Trmac <mitr@redhat.com>
	10	*/
	11
	12	#include <linux/audit.h>
5a0e3ad6	13	#include <linux/slab.h>
522ed776 MT	14	#include <linux/tty.h>
	15
	16	struct tty_audit_buf {
	17	atomic_t count;
	18	struct mutex mutex; /* Protects all data below */
	19	int major, minor; /* The TTY which the data is from */
	20	unsigned icanon:1;
	21	size_t valid;
	22	unsigned char data; / Allocated size N_TTY_BUF_SIZE */
	23	};
	24
	25	static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
6c633f27	26	unsigned icanon)
522ed776 MT	27	{
	28	struct tty_audit_buf *buf;
	29
66c6ceae	30	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
522ed776 MT	31	if (!buf)
522ed776 MT	32	goto err;
c481c707	33	buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
522ed776 MT	34	if (!buf->data)
	35	goto err_buf;
	36	atomic_set(&buf->count, 1);
	37	mutex_init(&buf->mutex);
	38	buf->major = major;
	39	buf->minor = minor;
	40	buf->icanon = icanon;
	41	buf->valid = 0;
	42	return buf;
	43
	44	err_buf:
	45	kfree(buf);
	46	err:
	47	return NULL;
	48	}
	49
	50	static void tty_audit_buf_free(struct tty_audit_buf *buf)
	51	{
	52	WARN_ON(buf->valid != 0);
c481c707	53	kfree(buf->data);
522ed776 MT	54	kfree(buf);
	55	}
	56
	57	static void tty_audit_buf_put(struct tty_audit_buf *buf)
	58	{
	59	if (atomic_dec_and_test(&buf->count))
	60	tty_audit_buf_free(buf);
	61	}
	62
1e641743	63	static void tty_audit_log(const char description, struct task_struct tsk,
e1760bd5	64	kuid_t loginuid, unsigned sessionid, int major,
1e641743	65	int minor, unsigned char *data, size_t size)
522ed776 MT	66	{
	67	struct audit_buffer *ab;
	68
522ed776 MT	69	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
	70	if (ab) {
	71	char name[sizeof(tsk->comm)];
cca080d9	72	kuid_t uid = task_uid(tsk);
522ed776	73
1e641743 AV	74	audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
1e641743 AV	75	"major=%d minor=%d comm=", description,
cca080d9 EB	76	tsk->pid,
cca080d9 EB	77	from_kuid(&init_user_ns, uid),
e1760bd5 EB	78	from_kuid(&init_user_ns, loginuid),
e1760bd5 EB	79	sessionid,
1e641743	80	major, minor);
522ed776 MT	81	get_task_comm(name, tsk);
	82	audit_log_untrustedstring(ab, name);
	83	audit_log_format(ab, " data=");
1e641743	84	audit_log_n_hex(ab, data, size);
522ed776 MT	85	audit_log_end(ab);
522ed776 MT	86	}
1e641743 AV	87	}
	88
	89	/**
	90	* tty_audit_buf_push - Push buffered data out
	91	*
	92	* Generate an audit message from the contents of @buf, which is owned by
	93	* @tsk with @loginuid. @buf->mutex must be locked.
	94	*/
e1760bd5	95	static void tty_audit_buf_push(struct task_struct *tsk, kuid_t loginuid,
1e641743 AV	96	unsigned int sessionid,
	97	struct tty_audit_buf *buf)
	98	{
	99	if (buf->valid == 0)
	100	return;
00bff392 XF	101	if (audit_enabled == 0) {
00bff392 XF	102	buf->valid = 0;
1e641743	103	return;
00bff392	104	}
1e641743 AV	105	tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
1e641743 AV	106	buf->data, buf->valid);
522ed776 MT	107	buf->valid = 0;
	108	}
	109
	110	/**
	111	* tty_audit_buf_push_current - Push buffered data out
	112	*
	113	* Generate an audit message from the contents of @buf, which is owned by
	114	* the current task. @buf->mutex must be locked.
	115	*/
	116	static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
	117	{
e1760bd5	118	kuid_t auid = audit_get_loginuid(current);
4746ec5b EP	119	unsigned int sessionid = audit_get_sessionid(current);
4746ec5b EP	120	tty_audit_buf_push(current, auid, sessionid, buf);
522ed776 MT	121	}
	122
	123	/**
	124	* tty_audit_exit - Handle a task exit
	125	*
	126	* Make sure all buffered data is written out and deallocate the buffer.
	127	* Only needs to be called if current->signal->tty_audit_buf != %NULL.
	128	*/
	129	void tty_audit_exit(void)
	130	{
	131	struct tty_audit_buf *buf;
	132
	133	spin_lock_irq(&current->sighand->siglock);
	134	buf = current->signal->tty_audit_buf;
	135	current->signal->tty_audit_buf = NULL;
	136	spin_unlock_irq(&current->sighand->siglock);
	137	if (!buf)
	138	return;
	139
	140	mutex_lock(&buf->mutex);
	141	tty_audit_buf_push_current(buf);
	142	mutex_unlock(&buf->mutex);
	143
	144	tty_audit_buf_put(buf);
	145	}
	146
	147	/**
	148	* tty_audit_fork - Copy TTY audit state for a new task
	149	*
	150	* Set up TTY audit state in @sig from current. @sig needs no locking.
	151	*/
	152	void tty_audit_fork(struct signal_struct *sig)
	153	{
	154	spin_lock_irq(&current->sighand->siglock);
	155	sig->audit_tty = current->signal->audit_tty;
	156	spin_unlock_irq(&current->sighand->siglock);
522ed776 MT	157	}
522ed776 MT	158
1e641743 AV	159	/**
	160	* tty_audit_tiocsti - Log TIOCSTI
	161	*/
	162	void tty_audit_tiocsti(struct tty_struct *tty, char ch)
	163	{
	164	struct tty_audit_buf *buf;
	165	int major, minor, should_audit;
	166
	167	spin_lock_irq(&current->sighand->siglock);
	168	should_audit = current->signal->audit_tty;
	169	buf = current->signal->tty_audit_buf;
	170	if (buf)
	171	atomic_inc(&buf->count);
	172	spin_unlock_irq(&current->sighand->siglock);
	173
	174	major = tty->driver->major;
	175	minor = tty->driver->minor_start + tty->index;
	176	if (buf) {
	177	mutex_lock(&buf->mutex);
	178	if (buf->major == major && buf->minor == minor)
	179	tty_audit_buf_push_current(buf);
	180	mutex_unlock(&buf->mutex);
	181	tty_audit_buf_put(buf);
	182	}
	183
	184	if (should_audit && audit_enabled) {
e1760bd5	185	kuid_t auid;
1e641743 AV	186	unsigned int sessionid;
	187
	188	auid = audit_get_loginuid(current);
	189	sessionid = audit_get_sessionid(current);
	190	tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
	191	minor, &ch, 1);
	192	}
	193	}
	194
522ed776	195	/**
3c80fe4a TG	196	* tty_audit_push_task - Flush task's pending audit data
	197	* @tsk: task pointer
	198	* @loginuid: sender login uid
	199	* @sessionid: sender session id
	200	*
	201	* Called with a ref on @tsk held. Try to lock sighand and get a
	202	* reference to the tty audit buffer if available.
	203	* Flush the buffer or return an appropriate error code.
522ed776	204	*/
e1760bd5	205	int tty_audit_push_task(struct task_struct *tsk, kuid_t loginuid, u32 sessionid)
522ed776	206	{
3c80fe4a TG	207	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
3c80fe4a TG	208	unsigned long flags;
522ed776	209
3c80fe4a TG	210	if (!lock_task_sighand(tsk, &flags))
	211	return -ESRCH;
	212
	213	if (tsk->signal->audit_tty) {
	214	buf = tsk->signal->tty_audit_buf;
	215	if (buf)
	216	atomic_inc(&buf->count);
	217	}
	218	unlock_task_sighand(tsk, &flags);
	219
	220	/*
	221	* Return 0 when signal->audit_tty set
	222	* but tsk->signal->tty_audit_buf == NULL.
	223	*/
	224	if (!buf \|\| IS_ERR(buf))
	225	return PTR_ERR(buf);
522ed776 MT	226
522ed776 MT	227	mutex_lock(&buf->mutex);
4746ec5b	228	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
522ed776 MT	229	mutex_unlock(&buf->mutex);
	230
	231	tty_audit_buf_put(buf);
3c80fe4a	232	return 0;
522ed776 MT	233	}
	234
	235	/**
	236	* tty_audit_buf_get - Get an audit buffer.
	237	*
	238	* Get an audit buffer for @tty, allocate it if necessary. Return %NULL
	239	* if TTY auditing is disabled or out of memory. Otherwise, return a new
	240	* reference to the buffer.
	241	*/
6c633f27 JS	242	static struct tty_audit_buf tty_audit_buf_get(struct tty_struct tty,
6c633f27 JS	243	unsigned icanon)
522ed776 MT	244	{
	245	struct tty_audit_buf buf, buf2;
	246
	247	buf = NULL;
	248	buf2 = NULL;
	249	spin_lock_irq(&current->sighand->siglock);
	250	if (likely(!current->signal->audit_tty))
	251	goto out;
	252	buf = current->signal->tty_audit_buf;
	253	if (buf) {
	254	atomic_inc(&buf->count);
	255	goto out;
	256	}
	257	spin_unlock_irq(&current->sighand->siglock);
	258
	259	buf2 = tty_audit_buf_alloc(tty->driver->major,
	260	tty->driver->minor_start + tty->index,
6c633f27	261	icanon);
522ed776 MT	262	if (buf2 == NULL) {
	263	audit_log_lost("out of memory in TTY auditing");
	264	return NULL;
	265	}
	266
	267	spin_lock_irq(&current->sighand->siglock);
	268	if (!current->signal->audit_tty)
	269	goto out;
	270	buf = current->signal->tty_audit_buf;
	271	if (!buf) {
	272	current->signal->tty_audit_buf = buf2;
	273	buf = buf2;
	274	buf2 = NULL;
	275	}
	276	atomic_inc(&buf->count);
	277	/* Fall through */
	278	out:
	279	spin_unlock_irq(&current->sighand->siglock);
	280	if (buf2)
	281	tty_audit_buf_free(buf2);
	282	return buf;
	283	}
	284
	285	/**
	286	* tty_audit_add_data - Add data for TTY auditing.
	287	*
	288	* Audit @data of @size from @tty, if necessary.
	289	*/
	290	void tty_audit_add_data(struct tty_struct tty, unsigned char data,
6c633f27	291	size_t size, unsigned icanon)
522ed776 MT	292	{
	293	struct tty_audit_buf *buf;
	294	int major, minor;
	295
	296	if (unlikely(size == 0))
	297	return;
	298
41126226 MT	299	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	300	&& tty->driver->subtype == PTY_TYPE_MASTER)
	301	return;
	302
6c633f27	303	buf = tty_audit_buf_get(tty, icanon);
522ed776 MT	304	if (!buf)
	305	return;
	306
	307	mutex_lock(&buf->mutex);
	308	major = tty->driver->major;
	309	minor = tty->driver->minor_start + tty->index;
	310	if (buf->major != major \|\| buf->minor != minor
6c633f27	311	\|\| buf->icanon != icanon) {
522ed776 MT	312	tty_audit_buf_push_current(buf);
	313	buf->major = major;
	314	buf->minor = minor;
6c633f27	315	buf->icanon = icanon;
522ed776 MT	316	}
	317	do {
	318	size_t run;
	319
	320	run = N_TTY_BUF_SIZE - buf->valid;
	321	if (run > size)
	322	run = size;
	323	memcpy(buf->data + buf->valid, data, run);
	324	buf->valid += run;
	325	data += run;
	326	size -= run;
	327	if (buf->valid == N_TTY_BUF_SIZE)
	328	tty_audit_buf_push_current(buf);
	329	} while (size != 0);
	330	mutex_unlock(&buf->mutex);
	331	tty_audit_buf_put(buf);
	332	}
	333
	334	/**
	335	* tty_audit_push - Push buffered data out
	336	*
	337	* Make sure no audit data is pending for @tty on the current process.
	338	*/
	339	void tty_audit_push(struct tty_struct *tty)
	340	{
	341	struct tty_audit_buf *buf;
	342
	343	spin_lock_irq(&current->sighand->siglock);
	344	if (likely(!current->signal->audit_tty)) {
	345	spin_unlock_irq(&current->sighand->siglock);
	346	return;
	347	}
	348	buf = current->signal->tty_audit_buf;
	349	if (buf)
	350	atomic_inc(&buf->count);
	351	spin_unlock_irq(&current->sighand->siglock);
	352
	353	if (buf) {
	354	int major, minor;
	355
	356	major = tty->driver->major;
	357	minor = tty->driver->minor_start + tty->index;
	358	mutex_lock(&buf->mutex);
	359	if (buf->major == major && buf->minor == minor)
	360	tty_audit_buf_push_current(buf);
	361	mutex_unlock(&buf->mutex);
	362	tty_audit_buf_put(buf);
	363	}
	364	}