[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 <[email protected]>
 */

#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) {
		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)
{
	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 <[email protected]>
	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;
00bff392 XF	98	if (audit_enabled == 0) {
00bff392 XF	99	buf->valid = 0;
1e641743	100	return;
00bff392	101	}
1e641743 AV	102	tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
1e641743 AV	103	buf->data, buf->valid);
522ed776 MT	104	buf->valid = 0;
	105	}
	106
	107	/**
	108	* tty_audit_buf_push_current - Push buffered data out
	109	*
	110	* Generate an audit message from the contents of @buf, which is owned by
	111	* the current task. @buf->mutex must be locked.
	112	*/
	113	static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
	114	{
4746ec5b EP	115	uid_t auid = audit_get_loginuid(current);
	116	unsigned int sessionid = audit_get_sessionid(current);
	117	tty_audit_buf_push(current, auid, sessionid, buf);
522ed776 MT	118	}
	119
	120	/**
	121	* tty_audit_exit - Handle a task exit
	122	*
	123	* Make sure all buffered data is written out and deallocate the buffer.
	124	* Only needs to be called if current->signal->tty_audit_buf != %NULL.
	125	*/
	126	void tty_audit_exit(void)
	127	{
	128	struct tty_audit_buf *buf;
	129
	130	spin_lock_irq(&current->sighand->siglock);
	131	buf = current->signal->tty_audit_buf;
	132	current->signal->tty_audit_buf = NULL;
	133	spin_unlock_irq(&current->sighand->siglock);
	134	if (!buf)
	135	return;
	136
	137	mutex_lock(&buf->mutex);
	138	tty_audit_buf_push_current(buf);
	139	mutex_unlock(&buf->mutex);
	140
	141	tty_audit_buf_put(buf);
	142	}
	143
	144	/**
	145	* tty_audit_fork - Copy TTY audit state for a new task
	146	*
	147	* Set up TTY audit state in @sig from current. @sig needs no locking.
	148	*/
	149	void tty_audit_fork(struct signal_struct *sig)
	150	{
	151	spin_lock_irq(&current->sighand->siglock);
	152	sig->audit_tty = current->signal->audit_tty;
	153	spin_unlock_irq(&current->sighand->siglock);
522ed776 MT	154	}
522ed776 MT	155
1e641743 AV	156	/**
	157	* tty_audit_tiocsti - Log TIOCSTI
	158	*/
	159	void tty_audit_tiocsti(struct tty_struct *tty, char ch)
	160	{
	161	struct tty_audit_buf *buf;
	162	int major, minor, should_audit;
	163
	164	spin_lock_irq(&current->sighand->siglock);
	165	should_audit = current->signal->audit_tty;
	166	buf = current->signal->tty_audit_buf;
	167	if (buf)
	168	atomic_inc(&buf->count);
	169	spin_unlock_irq(&current->sighand->siglock);
	170
	171	major = tty->driver->major;
	172	minor = tty->driver->minor_start + tty->index;
	173	if (buf) {
	174	mutex_lock(&buf->mutex);
	175	if (buf->major == major && buf->minor == minor)
	176	tty_audit_buf_push_current(buf);
	177	mutex_unlock(&buf->mutex);
	178	tty_audit_buf_put(buf);
	179	}
	180
	181	if (should_audit && audit_enabled) {
	182	uid_t auid;
	183	unsigned int sessionid;
	184
	185	auid = audit_get_loginuid(current);
	186	sessionid = audit_get_sessionid(current);
	187	tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
	188	minor, &ch, 1);
	189	}
	190	}
	191
522ed776	192	/**
3c80fe4a TG	193	* tty_audit_push_task - Flush task's pending audit data
	194	* @tsk: task pointer
	195	* @loginuid: sender login uid
	196	* @sessionid: sender session id
	197	*
	198	* Called with a ref on @tsk held. Try to lock sighand and get a
	199	* reference to the tty audit buffer if available.
	200	* Flush the buffer or return an appropriate error code.
522ed776	201	*/
3c80fe4a	202	int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
522ed776	203	{
3c80fe4a TG	204	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
3c80fe4a TG	205	unsigned long flags;
522ed776	206
3c80fe4a TG	207	if (!lock_task_sighand(tsk, &flags))
	208	return -ESRCH;
	209
	210	if (tsk->signal->audit_tty) {
	211	buf = tsk->signal->tty_audit_buf;
	212	if (buf)
	213	atomic_inc(&buf->count);
	214	}
	215	unlock_task_sighand(tsk, &flags);
	216
	217	/*
	218	* Return 0 when signal->audit_tty set
	219	* but tsk->signal->tty_audit_buf == NULL.
	220	*/
	221	if (!buf \|\| IS_ERR(buf))
	222	return PTR_ERR(buf);
522ed776 MT	223
522ed776 MT	224	mutex_lock(&buf->mutex);
4746ec5b	225	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
522ed776 MT	226	mutex_unlock(&buf->mutex);
	227
	228	tty_audit_buf_put(buf);
3c80fe4a	229	return 0;
522ed776 MT	230	}
	231
	232	/**
	233	* tty_audit_buf_get - Get an audit buffer.
	234	*
	235	* Get an audit buffer for @tty, allocate it if necessary. Return %NULL
	236	* if TTY auditing is disabled or out of memory. Otherwise, return a new
	237	* reference to the buffer.
	238	*/
	239	static struct tty_audit_buf tty_audit_buf_get(struct tty_struct tty)
	240	{
	241	struct tty_audit_buf buf, buf2;
	242
	243	buf = NULL;
	244	buf2 = NULL;
	245	spin_lock_irq(&current->sighand->siglock);
	246	if (likely(!current->signal->audit_tty))
	247	goto out;
	248	buf = current->signal->tty_audit_buf;
	249	if (buf) {
	250	atomic_inc(&buf->count);
	251	goto out;
	252	}
	253	spin_unlock_irq(&current->sighand->siglock);
	254
	255	buf2 = tty_audit_buf_alloc(tty->driver->major,
	256	tty->driver->minor_start + tty->index,
	257	tty->icanon);
	258	if (buf2 == NULL) {
	259	audit_log_lost("out of memory in TTY auditing");
	260	return NULL;
	261	}
	262
	263	spin_lock_irq(&current->sighand->siglock);
	264	if (!current->signal->audit_tty)
	265	goto out;
	266	buf = current->signal->tty_audit_buf;
	267	if (!buf) {
	268	current->signal->tty_audit_buf = buf2;
	269	buf = buf2;
	270	buf2 = NULL;
	271	}
	272	atomic_inc(&buf->count);
	273	/* Fall through */
	274	out:
	275	spin_unlock_irq(&current->sighand->siglock);
	276	if (buf2)
	277	tty_audit_buf_free(buf2);
	278	return buf;
	279	}
	280
	281	/**
	282	* tty_audit_add_data - Add data for TTY auditing.
	283	*
	284	* Audit @data of @size from @tty, if necessary.
	285	*/
	286	void tty_audit_add_data(struct tty_struct tty, unsigned char data,
	287	size_t size)
	288	{
	289	struct tty_audit_buf *buf;
	290	int major, minor;
	291
	292	if (unlikely(size == 0))
	293	return;
294
41126226 MT	295	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	296	&& tty->driver->subtype == PTY_TYPE_MASTER)
	297	return;
	298
522ed776 MT	299	buf = tty_audit_buf_get(tty);
	300	if (!buf)
	301	return;
	302
	303	mutex_lock(&buf->mutex);
	304	major = tty->driver->major;
	305	minor = tty->driver->minor_start + tty->index;
	306	if (buf->major != major \|\| buf->minor != minor
	307	\|\| buf->icanon != tty->icanon) {
	308	tty_audit_buf_push_current(buf);
	309	buf->major = major;
	310	buf->minor = minor;
	311	buf->icanon = tty->icanon;
	312	}
	313	do {
	314	size_t run;
	315
	316	run = N_TTY_BUF_SIZE - buf->valid;
	317	if (run > size)
	318	run = size;
	319	memcpy(buf->data + buf->valid, data, run);
	320	buf->valid += run;
	321	data += run;
	322	size -= run;
	323	if (buf->valid == N_TTY_BUF_SIZE)
	324	tty_audit_buf_push_current(buf);
	325	} while (size != 0);
	326	mutex_unlock(&buf->mutex);
	327	tty_audit_buf_put(buf);
	328	}
	329
	330	/**
	331	* tty_audit_push - Push buffered data out
	332	*
	333	* Make sure no audit data is pending for @tty on the current process.
	334	*/
	335	void tty_audit_push(struct tty_struct *tty)
	336	{
	337	struct tty_audit_buf *buf;
	338
	339	spin_lock_irq(&current->sighand->siglock);
	340	if (likely(!current->signal->audit_tty)) {
	341	spin_unlock_irq(&current->sighand->siglock);
	342	return;
	343	}
	344	buf = current->signal->tty_audit_buf;
	345	if (buf)
	346	atomic_inc(&buf->count);
	347	spin_unlock_irq(&current->sighand->siglock);
	348
	349	if (buf) {
	350	int major, minor;
	351
	352	major = tty->driver->major;
	353	minor = tty->driver->minor_start + tty->index;
	354	mutex_lock(&buf->mutex);
	355	if (buf->major == major && buf->minor == minor)
	356	tty_audit_buf_push_current(buf);
	357	mutex_unlock(&buf->mutex);
	358	tty_audit_buf_put(buf);
	359	}
	360	}