[mirror_ubuntu-bionic-kernel.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, int major, int minor,
			  unsigned char *data, size_t size)
{
	struct audit_buffer *ab;
	struct task_struct *tsk = current;
	uid_t uid = from_kuid(&init_user_ns, task_uid(tsk));
	uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk));
	u32 sessionid = audit_get_sessionid(tsk);

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

		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
 *	the current task.  @buf->mutex must be locked.
 */
static void tty_audit_buf_push(struct tty_audit_buf *buf)
{
	if (buf->valid == 0)
		return;
	if (audit_enabled == 0) {
		buf->valid = 0;
		return;
	}
	tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid);
	buf->valid = 0;
}

/**
 *	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;
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	buf = current->signal->tty_audit_buf;
	current->signal->tty_audit_buf = NULL;
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
	if (!buf)
		return;

	mutex_lock(&buf->mutex);
	tty_audit_buf_push(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)
{
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	sig->audit_tty = current->signal->audit_tty;
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

/**
 *	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;
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	should_audit = current->signal->audit_tty;
	buf = current->signal->tty_audit_buf;
	if (buf)
		atomic_inc(&buf->count);
	spin_unlock_irqrestore(&current->sighand->siglock, flags);

	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(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", major, minor, &ch, 1);
	}
}

/**
 * tty_audit_push_current -	Flush current's pending audit data
 *
 * 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_current(void)
{
	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
	struct task_struct *tsk = current;
	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(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;
	unsigned long flags;

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

	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_irqsave(&current->sighand->siglock, flags);
	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_irqrestore(&current->sighand->siglock, flags);
	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(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(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;
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	if (likely(!current->signal->audit_tty)) {
		spin_unlock_irqrestore(&current->sighand->siglock, flags);
		return;
	}
	buf = current->signal->tty_audit_buf;
	if (buf)
		atomic_inc(&buf->count);
	spin_unlock_irqrestore(&current->sighand->siglock, flags);

	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(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
152f497b EP	63	static void tty_audit_log(const char *description, int major, int minor,
152f497b EP	64	unsigned char *data, size_t size)
522ed776 MT	65	{
522ed776 MT	66	struct audit_buffer *ab;
152f497b EP	67	struct task_struct *tsk = current;
	68	uid_t uid = from_kuid(&init_user_ns, task_uid(tsk));
	69	uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk));
	70	u32 sessionid = audit_get_sessionid(tsk);
522ed776	71
522ed776 MT	72	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
	73	if (ab) {
	74	char name[sizeof(tsk->comm)];
152f497b EP	75
	76	audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
	77	" minor=%d comm=", description, tsk->pid, uid,
	78	loginuid, sessionid, major, minor);
522ed776 MT	79	get_task_comm(name, tsk);
	80	audit_log_untrustedstring(ab, name);
	81	audit_log_format(ab, " data=");
1e641743	82	audit_log_n_hex(ab, data, size);
522ed776 MT	83	audit_log_end(ab);
522ed776 MT	84	}
1e641743 AV	85	}
	86
	87	/**
	88	* tty_audit_buf_push - Push buffered data out
	89	*
	90	* Generate an audit message from the contents of @buf, which is owned by
152f497b	91	* the current task. @buf->mutex must be locked.
1e641743	92	*/
152f497b	93	static void tty_audit_buf_push(struct tty_audit_buf *buf)
1e641743 AV	94	{
	95	if (buf->valid == 0)
	96	return;
00bff392 XF	97	if (audit_enabled == 0) {
00bff392 XF	98	buf->valid = 0;
1e641743	99	return;
00bff392	100	}
152f497b	101	tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid);
522ed776 MT	102	buf->valid = 0;
	103	}
	104
522ed776 MT	105	/**
	106	* tty_audit_exit - Handle a task exit
	107	*
	108	* Make sure all buffered data is written out and deallocate the buffer.
	109	* Only needs to be called if current->signal->tty_audit_buf != %NULL.
	110	*/
	111	void tty_audit_exit(void)
	112	{
	113	struct tty_audit_buf *buf;
bde02ca8	114	unsigned long flags;
522ed776	115
bde02ca8	116	spin_lock_irqsave(&current->sighand->siglock, flags);
522ed776 MT	117	buf = current->signal->tty_audit_buf;
522ed776 MT	118	current->signal->tty_audit_buf = NULL;
bde02ca8	119	spin_unlock_irqrestore(&current->sighand->siglock, flags);
522ed776 MT	120	if (!buf)
	121	return;
	122
	123	mutex_lock(&buf->mutex);
152f497b	124	tty_audit_buf_push(buf);
522ed776 MT	125	mutex_unlock(&buf->mutex);
	126
	127	tty_audit_buf_put(buf);
	128	}
	129
	130	/**
	131	* tty_audit_fork - Copy TTY audit state for a new task
	132	*
	133	* Set up TTY audit state in @sig from current. @sig needs no locking.
	134	*/
	135	void tty_audit_fork(struct signal_struct *sig)
	136	{
bde02ca8 EP	137	unsigned long flags;
	138
	139	spin_lock_irqsave(&current->sighand->siglock, flags);
522ed776	140	sig->audit_tty = current->signal->audit_tty;
bde02ca8	141	spin_unlock_irqrestore(&current->sighand->siglock, flags);
522ed776 MT	142	}
522ed776 MT	143
1e641743 AV	144	/**
	145	* tty_audit_tiocsti - Log TIOCSTI
	146	*/
	147	void tty_audit_tiocsti(struct tty_struct *tty, char ch)
	148	{
	149	struct tty_audit_buf *buf;
	150	int major, minor, should_audit;
bde02ca8	151	unsigned long flags;
1e641743	152
bde02ca8	153	spin_lock_irqsave(&current->sighand->siglock, flags);
1e641743 AV	154	should_audit = current->signal->audit_tty;
	155	buf = current->signal->tty_audit_buf;
	156	if (buf)
	157	atomic_inc(&buf->count);
bde02ca8	158	spin_unlock_irqrestore(&current->sighand->siglock, flags);
1e641743 AV	159
	160	major = tty->driver->major;
	161	minor = tty->driver->minor_start + tty->index;
	162	if (buf) {
	163	mutex_lock(&buf->mutex);
	164	if (buf->major == major && buf->minor == minor)
152f497b	165	tty_audit_buf_push(buf);
1e641743 AV	166	mutex_unlock(&buf->mutex);
	167	tty_audit_buf_put(buf);
	168	}
	169
	170	if (should_audit && audit_enabled) {
e1760bd5	171	kuid_t auid;
1e641743 AV	172	unsigned int sessionid;
	173
	174	auid = audit_get_loginuid(current);
	175	sessionid = audit_get_sessionid(current);
152f497b	176	tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1);
1e641743 AV	177	}
	178	}
	179
522ed776	180	/**
152f497b	181	* tty_audit_push_current - Flush current's pending audit data
3c80fe4a	182	*
152f497b	183	* Try to lock sighand and get a reference to the tty audit buffer if available.
3c80fe4a	184	* Flush the buffer or return an appropriate error code.
522ed776	185	*/
152f497b	186	int tty_audit_push_current(void)
522ed776	187	{
3c80fe4a	188	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
152f497b	189	struct task_struct *tsk = current;
3c80fe4a	190	unsigned long flags;
522ed776	191
3c80fe4a TG	192	if (!lock_task_sighand(tsk, &flags))
	193	return -ESRCH;
	194
	195	if (tsk->signal->audit_tty) {
	196	buf = tsk->signal->tty_audit_buf;
	197	if (buf)
	198	atomic_inc(&buf->count);
	199	}
	200	unlock_task_sighand(tsk, &flags);
	201
	202	/*
	203	* Return 0 when signal->audit_tty set
	204	* but tsk->signal->tty_audit_buf == NULL.
	205	*/
	206	if (!buf \|\| IS_ERR(buf))
	207	return PTR_ERR(buf);
522ed776 MT	208
522ed776 MT	209	mutex_lock(&buf->mutex);
152f497b	210	tty_audit_buf_push(buf);
522ed776 MT	211	mutex_unlock(&buf->mutex);
	212
	213	tty_audit_buf_put(buf);
3c80fe4a	214	return 0;
522ed776 MT	215	}
	216
	217	/**
	218	* tty_audit_buf_get - Get an audit buffer.
	219	*
	220	* Get an audit buffer for @tty, allocate it if necessary. Return %NULL
	221	* if TTY auditing is disabled or out of memory. Otherwise, return a new
	222	* reference to the buffer.
	223	*/
6c633f27 JS	224	static struct tty_audit_buf tty_audit_buf_get(struct tty_struct tty,
6c633f27 JS	225	unsigned icanon)
522ed776 MT	226	{
522ed776 MT	227	struct tty_audit_buf buf, buf2;
bde02ca8	228	unsigned long flags;
522ed776 MT	229
	230	buf = NULL;
	231	buf2 = NULL;
bde02ca8	232	spin_lock_irqsave(&current->sighand->siglock, flags);
522ed776 MT	233	if (likely(!current->signal->audit_tty))
	234	goto out;
	235	buf = current->signal->tty_audit_buf;
	236	if (buf) {
	237	atomic_inc(&buf->count);
	238	goto out;
	239	}
bde02ca8	240	spin_unlock_irqrestore(&current->sighand->siglock, flags);
522ed776 MT	241
	242	buf2 = tty_audit_buf_alloc(tty->driver->major,
	243	tty->driver->minor_start + tty->index,
6c633f27	244	icanon);
522ed776 MT	245	if (buf2 == NULL) {
	246	audit_log_lost("out of memory in TTY auditing");
	247	return NULL;
	248	}
	249
bde02ca8	250	spin_lock_irqsave(&current->sighand->siglock, flags);
522ed776 MT	251	if (!current->signal->audit_tty)
	252	goto out;
	253	buf = current->signal->tty_audit_buf;
	254	if (!buf) {
	255	current->signal->tty_audit_buf = buf2;
	256	buf = buf2;
	257	buf2 = NULL;
	258	}
	259	atomic_inc(&buf->count);
	260	/* Fall through */
	261	out:
bde02ca8	262	spin_unlock_irqrestore(&current->sighand->siglock, flags);
522ed776 MT	263	if (buf2)
	264	tty_audit_buf_free(buf2);
	265	return buf;
	266	}
	267
	268	/**
	269	* tty_audit_add_data - Add data for TTY auditing.
	270	*
	271	* Audit @data of @size from @tty, if necessary.
	272	*/
	273	void tty_audit_add_data(struct tty_struct tty, unsigned char data,
6c633f27	274	size_t size, unsigned icanon)
522ed776 MT	275	{
	276	struct tty_audit_buf *buf;
	277	int major, minor;
	278
	279	if (unlikely(size == 0))
	280	return;
	281
41126226 MT	282	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	283	&& tty->driver->subtype == PTY_TYPE_MASTER)
	284	return;
	285
6c633f27	286	buf = tty_audit_buf_get(tty, icanon);
522ed776 MT	287	if (!buf)
	288	return;
	289
	290	mutex_lock(&buf->mutex);
	291	major = tty->driver->major;
	292	minor = tty->driver->minor_start + tty->index;
	293	if (buf->major != major \|\| buf->minor != minor
6c633f27	294	\|\| buf->icanon != icanon) {
152f497b	295	tty_audit_buf_push(buf);
522ed776 MT	296	buf->major = major;
522ed776 MT	297	buf->minor = minor;
6c633f27	298	buf->icanon = icanon;
522ed776 MT	299	}
	300	do {
	301	size_t run;
	302
	303	run = N_TTY_BUF_SIZE - buf->valid;
	304	if (run > size)
	305	run = size;
	306	memcpy(buf->data + buf->valid, data, run);
	307	buf->valid += run;
	308	data += run;
	309	size -= run;
	310	if (buf->valid == N_TTY_BUF_SIZE)
152f497b	311	tty_audit_buf_push(buf);
522ed776 MT	312	} while (size != 0);
	313	mutex_unlock(&buf->mutex);
	314	tty_audit_buf_put(buf);
	315	}
	316
	317	/**
	318	* tty_audit_push - Push buffered data out
	319	*
	320	* Make sure no audit data is pending for @tty on the current process.
	321	*/
	322	void tty_audit_push(struct tty_struct *tty)
	323	{
	324	struct tty_audit_buf *buf;
bde02ca8	325	unsigned long flags;
522ed776	326
bde02ca8	327	spin_lock_irqsave(&current->sighand->siglock, flags);
522ed776	328	if (likely(!current->signal->audit_tty)) {
bde02ca8	329	spin_unlock_irqrestore(&current->sighand->siglock, flags);
522ed776 MT	330	return;
	331	}
	332	buf = current->signal->tty_audit_buf;
	333	if (buf)
	334	atomic_inc(&buf->count);
bde02ca8	335	spin_unlock_irqrestore(&current->sighand->siglock, flags);
522ed776 MT	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)
152f497b	344	tty_audit_buf_push(buf);
522ed776 MT	345	mutex_unlock(&buf->mutex);
	346	tty_audit_buf_put(buf);
	347	}
	348	}