[linux-2.6-block.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/file.h>
#include <linux/fdtable.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;
	if (PAGE_SIZE != N_TTY_BUF_SIZE)
		buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
	else
		buf->data = (unsigned char *)__get_free_page(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);
	if (PAGE_SIZE != N_TTY_BUF_SIZE)
		kfree(buf->data);
	else
		free_page((unsigned long)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);
	sig->tty_audit_buf = NULL;
}

/**
 *	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
 */
void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
{
	struct tty_audit_buf *buf;

	spin_lock_irq(&tsk->sighand->siglock);
	buf = tsk->signal->tty_audit_buf;
	if (buf)
		atomic_inc(&buf->count);
	spin_unlock_irq(&tsk->sighand->siglock);
	if (!buf)
		return;

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

	tty_audit_buf_put(buf);
}

/**
 *	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>
	13	#include <linux/file.h>
9f3acc31	14	#include <linux/fdtable.h>
522ed776 MT	15	#include <linux/tty.h>
	16
	17	struct tty_audit_buf {
	18	atomic_t count;
	19	struct mutex mutex; /* Protects all data below */
	20	int major, minor; /* The TTY which the data is from */
	21	unsigned icanon:1;
	22	size_t valid;
	23	unsigned char data; / Allocated size N_TTY_BUF_SIZE */
	24	};
	25
	26	static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
	27	int icanon)
	28	{
	29	struct tty_audit_buf *buf;
	30
66c6ceae	31	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
522ed776 MT	32	if (!buf)
	33	goto err;
	34	if (PAGE_SIZE != N_TTY_BUF_SIZE)
	35	buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
	36	else
	37	buf->data = (unsigned char *)__get_free_page(GFP_KERNEL);
	38	if (!buf->data)
	39	goto err_buf;
	40	atomic_set(&buf->count, 1);
	41	mutex_init(&buf->mutex);
	42	buf->major = major;
	43	buf->minor = minor;
	44	buf->icanon = icanon;
	45	buf->valid = 0;
	46	return buf;
	47
	48	err_buf:
	49	kfree(buf);
	50	err:
	51	return NULL;
	52	}
	53
	54	static void tty_audit_buf_free(struct tty_audit_buf *buf)
	55	{
	56	WARN_ON(buf->valid != 0);
	57	if (PAGE_SIZE != N_TTY_BUF_SIZE)
	58	kfree(buf->data);
	59	else
	60	free_page((unsigned long)buf->data);
	61	kfree(buf);
	62	}
	63
	64	static void tty_audit_buf_put(struct tty_audit_buf *buf)
	65	{
	66	if (atomic_dec_and_test(&buf->count))
	67	tty_audit_buf_free(buf);
	68	}
	69
1e641743 AV	70	static void tty_audit_log(const char description, struct task_struct tsk,
	71	uid_t loginuid, unsigned sessionid, int major,
	72	int minor, unsigned char *data, size_t size)
522ed776 MT	73	{
	74	struct audit_buffer *ab;
	75
522ed776 MT	76	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
	77	if (ab) {
	78	char name[sizeof(tsk->comm)];
66303bce	79	uid_t uid = task_uid(tsk);
522ed776	80
1e641743 AV	81	audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
1e641743 AV	82	"major=%d minor=%d comm=", description,
66303bce	83	tsk->pid, uid, loginuid, sessionid,
1e641743	84	major, minor);
522ed776 MT	85	get_task_comm(name, tsk);
	86	audit_log_untrustedstring(ab, name);
	87	audit_log_format(ab, " data=");
1e641743	88	audit_log_n_hex(ab, data, size);
522ed776 MT	89	audit_log_end(ab);
522ed776 MT	90	}
1e641743 AV	91	}
	92
	93	/**
	94	* tty_audit_buf_push - Push buffered data out
	95	*
	96	* Generate an audit message from the contents of @buf, which is owned by
	97	* @tsk with @loginuid. @buf->mutex must be locked.
	98	*/
	99	static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
	100	unsigned int sessionid,
	101	struct tty_audit_buf *buf)
	102	{
	103	if (buf->valid == 0)
	104	return;
	105	if (audit_enabled == 0)
	106	return;
	107	tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
	108	buf->data, buf->valid);
522ed776 MT	109	buf->valid = 0;
	110	}
	111
	112	/**
	113	* tty_audit_buf_push_current - Push buffered data out
	114	*
	115	* Generate an audit message from the contents of @buf, which is owned by
	116	* the current task. @buf->mutex must be locked.
	117	*/
	118	static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
	119	{
4746ec5b EP	120	uid_t auid = audit_get_loginuid(current);
	121	unsigned int sessionid = audit_get_sessionid(current);
	122	tty_audit_buf_push(current, auid, sessionid, buf);
522ed776 MT	123	}
	124
	125	/**
	126	* tty_audit_exit - Handle a task exit
	127	*
	128	* Make sure all buffered data is written out and deallocate the buffer.
	129	* Only needs to be called if current->signal->tty_audit_buf != %NULL.
	130	*/
	131	void tty_audit_exit(void)
	132	{
	133	struct tty_audit_buf *buf;
	134
	135	spin_lock_irq(&current->sighand->siglock);
	136	buf = current->signal->tty_audit_buf;
	137	current->signal->tty_audit_buf = NULL;
	138	spin_unlock_irq(&current->sighand->siglock);
	139	if (!buf)
	140	return;
	141
	142	mutex_lock(&buf->mutex);
	143	tty_audit_buf_push_current(buf);
	144	mutex_unlock(&buf->mutex);
	145
	146	tty_audit_buf_put(buf);
	147	}
	148
	149	/**
	150	* tty_audit_fork - Copy TTY audit state for a new task
	151	*
	152	* Set up TTY audit state in @sig from current. @sig needs no locking.
	153	*/
	154	void tty_audit_fork(struct signal_struct *sig)
	155	{
	156	spin_lock_irq(&current->sighand->siglock);
	157	sig->audit_tty = current->signal->audit_tty;
	158	spin_unlock_irq(&current->sighand->siglock);
	159	sig->tty_audit_buf = NULL;
	160	}
	161
1e641743 AV	162	/**
	163	* tty_audit_tiocsti - Log TIOCSTI
	164	*/
	165	void tty_audit_tiocsti(struct tty_struct *tty, char ch)
	166	{
	167	struct tty_audit_buf *buf;
	168	int major, minor, should_audit;
	169
	170	spin_lock_irq(&current->sighand->siglock);
	171	should_audit = current->signal->audit_tty;
	172	buf = current->signal->tty_audit_buf;
	173	if (buf)
	174	atomic_inc(&buf->count);
	175	spin_unlock_irq(&current->sighand->siglock);
	176
	177	major = tty->driver->major;
	178	minor = tty->driver->minor_start + tty->index;
	179	if (buf) {
	180	mutex_lock(&buf->mutex);
	181	if (buf->major == major && buf->minor == minor)
	182	tty_audit_buf_push_current(buf);
	183	mutex_unlock(&buf->mutex);
	184	tty_audit_buf_put(buf);
	185	}
	186
	187	if (should_audit && audit_enabled) {
	188	uid_t auid;
	189	unsigned int sessionid;
	190
	191	auid = audit_get_loginuid(current);
	192	sessionid = audit_get_sessionid(current);
	193	tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
	194	minor, &ch, 1);
	195	}
	196	}
	197
522ed776 MT	198	/**
	199	* tty_audit_push_task - Flush task's pending audit data
	200	*/
2532386f	201	void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
522ed776 MT	202	{
	203	struct tty_audit_buf *buf;
	204
	205	spin_lock_irq(&tsk->sighand->siglock);
	206	buf = tsk->signal->tty_audit_buf;
	207	if (buf)
	208	atomic_inc(&buf->count);
	209	spin_unlock_irq(&tsk->sighand->siglock);
	210	if (!buf)
	211	return;
	212
	213	mutex_lock(&buf->mutex);
4746ec5b	214	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
522ed776 MT	215	mutex_unlock(&buf->mutex);
	216
	217	tty_audit_buf_put(buf);
	218	}
	219
	220	/**
	221	* tty_audit_buf_get - Get an audit buffer.
	222	*
	223	* Get an audit buffer for @tty, allocate it if necessary. Return %NULL
	224	* if TTY auditing is disabled or out of memory. Otherwise, return a new
	225	* reference to the buffer.
	226	*/
	227	static struct tty_audit_buf tty_audit_buf_get(struct tty_struct tty)
	228	{
	229	struct tty_audit_buf buf, buf2;
	230
	231	buf = NULL;
	232	buf2 = NULL;
	233	spin_lock_irq(&current->sighand->siglock);
	234	if (likely(!current->signal->audit_tty))
	235	goto out;
	236	buf = current->signal->tty_audit_buf;
	237	if (buf) {
	238	atomic_inc(&buf->count);
	239	goto out;
	240	}
	241	spin_unlock_irq(&current->sighand->siglock);
	242
	243	buf2 = tty_audit_buf_alloc(tty->driver->major,
	244	tty->driver->minor_start + tty->index,
	245	tty->icanon);
	246	if (buf2 == NULL) {
	247	audit_log_lost("out of memory in TTY auditing");
	248	return NULL;
	249	}
	250
	251	spin_lock_irq(&current->sighand->siglock);
	252	if (!current->signal->audit_tty)
	253	goto out;
	254	buf = current->signal->tty_audit_buf;
	255	if (!buf) {
	256	current->signal->tty_audit_buf = buf2;
	257	buf = buf2;
	258	buf2 = NULL;
	259	}
	260	atomic_inc(&buf->count);
	261	/* Fall through */
	262	out:
	263	spin_unlock_irq(&current->sighand->siglock);
	264	if (buf2)
	265	tty_audit_buf_free(buf2);
	266	return buf;
	267	}
	268
	269	/**
	270	* tty_audit_add_data - Add data for TTY auditing.
	271	*
	272	* Audit @data of @size from @tty, if necessary.
	273	*/
	274	void tty_audit_add_data(struct tty_struct tty, unsigned char data,
	275	size_t size)
	276	{
	277	struct tty_audit_buf *buf;
	278	int major, minor;
279
280	if (unlikely(size == 0))
281	return;
282
41126226 MT	283	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	284	&& tty->driver->subtype == PTY_TYPE_MASTER)
	285	return;
	286
522ed776 MT	287	buf = tty_audit_buf_get(tty);
	288	if (!buf)
	289	return;
	290
	291	mutex_lock(&buf->mutex);
	292	major = tty->driver->major;
	293	minor = tty->driver->minor_start + tty->index;
	294	if (buf->major != major \|\| buf->minor != minor
	295	\|\| buf->icanon != tty->icanon) {
	296	tty_audit_buf_push_current(buf);
	297	buf->major = major;
	298	buf->minor = minor;
	299	buf->icanon = tty->icanon;
	300	}
	301	do {
	302	size_t run;
	303
	304	run = N_TTY_BUF_SIZE - buf->valid;
	305	if (run > size)
	306	run = size;
	307	memcpy(buf->data + buf->valid, data, run);
	308	buf->valid += run;
	309	data += run;
	310	size -= run;
	311	if (buf->valid == N_TTY_BUF_SIZE)
	312	tty_audit_buf_push_current(buf);
	313	} while (size != 0);
	314	mutex_unlock(&buf->mutex);
	315	tty_audit_buf_put(buf);
	316	}
	317
	318	/**
	319	* tty_audit_push - Push buffered data out
	320	*
	321	* Make sure no audit data is pending for @tty on the current process.
	322	*/
	323	void tty_audit_push(struct tty_struct *tty)
	324	{
	325	struct tty_audit_buf *buf;
	326
	327	spin_lock_irq(&current->sighand->siglock);
	328	if (likely(!current->signal->audit_tty)) {
	329	spin_unlock_irq(&current->sighand->siglock);
	330	return;
	331	}
	332	buf = current->signal->tty_audit_buf;
	333	if (buf)
	334	atomic_inc(&buf->count);
	335	spin_unlock_irq(&current->sighand->siglock);
	336
	337	if (buf) {
	338	int major, minor;
	339
	340	major = tty->driver->major;
	341	minor = tty->driver->minor_start + tty->index;
	342	mutex_lock(&buf->mutex);
	343	if (buf->major == major && buf->minor == minor)
	344	tty_audit_buf_push_current(buf);
	345	mutex_unlock(&buf->mutex);
	346	tty_audit_buf_put(buf);
	347	}
	348	}