[net-next-2.6.git] / drivers / char / 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,
						 int 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,
			  uid_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)];
		uid_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, uid, 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, uid_t loginuid,
			       unsigned int sessionid,
			       struct tty_audit_buf *buf)
{
	if (buf->valid == 0)
		return;
	if (audit_enabled == 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)
{
	uid_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) {
		uid_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, uid_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)
{
	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,
				   tty->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)
{
	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);
	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 != tty->icanon) {
		tty_audit_buf_push_current(buf);
		buf->major = major;
		buf->minor = minor;
		buf->icanon = tty->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,
	26	int icanon)
	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 AV	63	static void tty_audit_log(const char description, struct task_struct tsk,
	64	uid_t loginuid, unsigned sessionid, int major,
	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)];
66303bce	72	uid_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,
66303bce	76	tsk->pid, uid, loginuid, sessionid,
1e641743	77	major, minor);
522ed776 MT	78	get_task_comm(name, tsk);
	79	audit_log_untrustedstring(ab, name);
	80	audit_log_format(ab, " data=");
1e641743	81	audit_log_n_hex(ab, data, size);
522ed776 MT	82	audit_log_end(ab);
522ed776 MT	83	}
1e641743 AV	84	}
	85
	86	/**
	87	* tty_audit_buf_push - Push buffered data out
	88	*
	89	* Generate an audit message from the contents of @buf, which is owned by
	90	* @tsk with @loginuid. @buf->mutex must be locked.
	91	*/
	92	static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
	93	unsigned int sessionid,
	94	struct tty_audit_buf *buf)
	95	{
	96	if (buf->valid == 0)
	97	return;
	98	if (audit_enabled == 0)
	99	return;
	100	tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
	101	buf->data, buf->valid);
522ed776 MT	102	buf->valid = 0;
	103	}
	104
	105	/**
	106	* tty_audit_buf_push_current - Push buffered data out
	107	*
	108	* Generate an audit message from the contents of @buf, which is owned by
	109	* the current task. @buf->mutex must be locked.
	110	*/
	111	static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
	112	{
4746ec5b EP	113	uid_t auid = audit_get_loginuid(current);
	114	unsigned int sessionid = audit_get_sessionid(current);
	115	tty_audit_buf_push(current, auid, sessionid, buf);
522ed776 MT	116	}
	117
	118	/**
	119	* tty_audit_exit - Handle a task exit
	120	*
	121	* Make sure all buffered data is written out and deallocate the buffer.
	122	* Only needs to be called if current->signal->tty_audit_buf != %NULL.
	123	*/
	124	void tty_audit_exit(void)
	125	{
	126	struct tty_audit_buf *buf;
	127
	128	spin_lock_irq(&current->sighand->siglock);
	129	buf = current->signal->tty_audit_buf;
	130	current->signal->tty_audit_buf = NULL;
	131	spin_unlock_irq(&current->sighand->siglock);
	132	if (!buf)
	133	return;
	134
	135	mutex_lock(&buf->mutex);
	136	tty_audit_buf_push_current(buf);
	137	mutex_unlock(&buf->mutex);
	138
	139	tty_audit_buf_put(buf);
	140	}
	141
	142	/**
	143	* tty_audit_fork - Copy TTY audit state for a new task
	144	*
	145	* Set up TTY audit state in @sig from current. @sig needs no locking.
	146	*/
	147	void tty_audit_fork(struct signal_struct *sig)
	148	{
	149	spin_lock_irq(&current->sighand->siglock);
	150	sig->audit_tty = current->signal->audit_tty;
	151	spin_unlock_irq(&current->sighand->siglock);
522ed776 MT	152	}
522ed776 MT	153
1e641743 AV	154	/**
	155	* tty_audit_tiocsti - Log TIOCSTI
	156	*/
	157	void tty_audit_tiocsti(struct tty_struct *tty, char ch)
	158	{
	159	struct tty_audit_buf *buf;
	160	int major, minor, should_audit;
	161
	162	spin_lock_irq(&current->sighand->siglock);
	163	should_audit = current->signal->audit_tty;
	164	buf = current->signal->tty_audit_buf;
	165	if (buf)
	166	atomic_inc(&buf->count);
	167	spin_unlock_irq(&current->sighand->siglock);
	168
	169	major = tty->driver->major;
	170	minor = tty->driver->minor_start + tty->index;
	171	if (buf) {
	172	mutex_lock(&buf->mutex);
	173	if (buf->major == major && buf->minor == minor)
	174	tty_audit_buf_push_current(buf);
	175	mutex_unlock(&buf->mutex);
	176	tty_audit_buf_put(buf);
	177	}
	178
	179	if (should_audit && audit_enabled) {
	180	uid_t auid;
	181	unsigned int sessionid;
	182
	183	auid = audit_get_loginuid(current);
	184	sessionid = audit_get_sessionid(current);
	185	tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
	186	minor, &ch, 1);
	187	}
	188	}
	189
522ed776	190	/**
3c80fe4a TG	191	* tty_audit_push_task - Flush task's pending audit data
	192	* @tsk: task pointer
	193	* @loginuid: sender login uid
	194	* @sessionid: sender session id
	195	*
	196	* Called with a ref on @tsk held. Try to lock sighand and get a
	197	* reference to the tty audit buffer if available.
	198	* Flush the buffer or return an appropriate error code.
522ed776	199	*/
3c80fe4a	200	int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
522ed776	201	{
3c80fe4a TG	202	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
3c80fe4a TG	203	unsigned long flags;
522ed776	204
3c80fe4a TG	205	if (!lock_task_sighand(tsk, &flags))
	206	return -ESRCH;
	207
	208	if (tsk->signal->audit_tty) {
	209	buf = tsk->signal->tty_audit_buf;
	210	if (buf)
	211	atomic_inc(&buf->count);
	212	}
	213	unlock_task_sighand(tsk, &flags);
	214
	215	/*
	216	* Return 0 when signal->audit_tty set
	217	* but tsk->signal->tty_audit_buf == NULL.
	218	*/
	219	if (!buf \|\| IS_ERR(buf))
	220	return PTR_ERR(buf);
522ed776 MT	221
522ed776 MT	222	mutex_lock(&buf->mutex);
4746ec5b	223	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
522ed776 MT	224	mutex_unlock(&buf->mutex);
	225
	226	tty_audit_buf_put(buf);
3c80fe4a	227	return 0;
522ed776 MT	228	}
	229
	230	/**
	231	* tty_audit_buf_get - Get an audit buffer.
	232	*
	233	* Get an audit buffer for @tty, allocate it if necessary. Return %NULL
	234	* if TTY auditing is disabled or out of memory. Otherwise, return a new
	235	* reference to the buffer.
	236	*/
	237	static struct tty_audit_buf tty_audit_buf_get(struct tty_struct tty)
	238	{
	239	struct tty_audit_buf buf, buf2;
	240
	241	buf = NULL;
	242	buf2 = NULL;
	243	spin_lock_irq(&current->sighand->siglock);
	244	if (likely(!current->signal->audit_tty))
	245	goto out;
	246	buf = current->signal->tty_audit_buf;
	247	if (buf) {
	248	atomic_inc(&buf->count);
	249	goto out;
	250	}
	251	spin_unlock_irq(&current->sighand->siglock);
	252
	253	buf2 = tty_audit_buf_alloc(tty->driver->major,
	254	tty->driver->minor_start + tty->index,
	255	tty->icanon);
	256	if (buf2 == NULL) {
	257	audit_log_lost("out of memory in TTY auditing");
	258	return NULL;
	259	}
	260
	261	spin_lock_irq(&current->sighand->siglock);
	262	if (!current->signal->audit_tty)
	263	goto out;
	264	buf = current->signal->tty_audit_buf;
	265	if (!buf) {
	266	current->signal->tty_audit_buf = buf2;
	267	buf = buf2;
	268	buf2 = NULL;
	269	}
	270	atomic_inc(&buf->count);
	271	/* Fall through */
	272	out:
	273	spin_unlock_irq(&current->sighand->siglock);
	274	if (buf2)
	275	tty_audit_buf_free(buf2);
	276	return buf;
	277	}
	278
	279	/**
	280	* tty_audit_add_data - Add data for TTY auditing.
	281	*
	282	* Audit @data of @size from @tty, if necessary.
	283	*/
	284	void tty_audit_add_data(struct tty_struct tty, unsigned char data,
	285	size_t size)
	286	{
	287	struct tty_audit_buf *buf;
	288	int major, minor;
	289
	290	if (unlikely(size == 0))
	291	return;
292
41126226 MT	293	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	294	&& tty->driver->subtype == PTY_TYPE_MASTER)
	295	return;
	296
522ed776 MT	297	buf = tty_audit_buf_get(tty);
	298	if (!buf)
	299	return;
	300
	301	mutex_lock(&buf->mutex);
	302	major = tty->driver->major;
	303	minor = tty->driver->minor_start + tty->index;
	304	if (buf->major != major \|\| buf->minor != minor
	305	\|\| buf->icanon != tty->icanon) {
	306	tty_audit_buf_push_current(buf);
	307	buf->major = major;
	308	buf->minor = minor;
	309	buf->icanon = tty->icanon;
	310	}
	311	do {
	312	size_t run;
	313
	314	run = N_TTY_BUF_SIZE - buf->valid;
	315	if (run > size)
	316	run = size;
	317	memcpy(buf->data + buf->valid, data, run);
	318	buf->valid += run;
	319	data += run;
	320	size -= run;
	321	if (buf->valid == N_TTY_BUF_SIZE)
	322	tty_audit_buf_push_current(buf);
	323	} while (size != 0);
	324	mutex_unlock(&buf->mutex);
	325	tty_audit_buf_put(buf);
	326	}
	327
	328	/**
	329	* tty_audit_push - Push buffered data out
	330	*
	331	* Make sure no audit data is pending for @tty on the current process.
	332	*/
	333	void tty_audit_push(struct tty_struct *tty)
	334	{
	335	struct tty_audit_buf *buf;
	336
	337	spin_lock_irq(&current->sighand->siglock);
	338	if (likely(!current->signal->audit_tty)) {
	339	spin_unlock_irq(&current->sighand->siglock);
	340	return;
	341	}
	342	buf = current->signal->tty_audit_buf;
	343	if (buf)
	344	atomic_inc(&buf->count);
	345	spin_unlock_irq(&current->sighand->siglock);
	346
	347	if (buf) {
	348	int major, minor;
	349
	350	major = tty->driver->major;
	351	minor = tty->driver->minor_start + tty->index;
	352	mutex_lock(&buf->mutex);
	353	if (buf->major == major && buf->minor == minor)
	354	tty_audit_buf_push_current(buf);
	355	mutex_unlock(&buf->mutex);
	356	tty_audit_buf_put(buf);
	357	}
	358	}