[GitHub/LineageOS/android_kernel_samsung_universal7580.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);
}

/**
 *	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)
{
	struct audit_buffer *ab;

	if (buf->valid == 0)
		return;
	if (audit_enabled == 0)
		return;
	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, "tty pid=%u uid=%u auid=%u ses=%u "
				 "major=%d minor=%d comm=",
				 tsk->pid, uid, loginuid, sessionid,
				 buf->major, buf->minor);
		get_task_comm(name, tsk);
		audit_log_untrustedstring(ab, name);
		audit_log_format(ab, " data=");
		audit_log_n_hex(ab, buf->data, buf->valid);
		audit_log_end(ab);
	}
	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_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
	70	/**
	71	* tty_audit_buf_push - Push buffered data out
	72	*
	73	* Generate an audit message from the contents of @buf, which is owned by
	74	* @tsk with @loginuid. @buf->mutex must be locked.
	75	*/
	76	static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
4746ec5b	77	unsigned int sessionid,
522ed776 MT	78	struct tty_audit_buf *buf)
	79	{
	80	struct audit_buffer *ab;
	81
	82	if (buf->valid == 0)
	83	return;
	84	if (audit_enabled == 0)
	85	return;
	86	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
	87	if (ab) {
	88	char name[sizeof(tsk->comm)];
66303bce	89	uid_t uid = task_uid(tsk);
522ed776	90
4746ec5b	91	audit_log_format(ab, "tty pid=%u uid=%u auid=%u ses=%u "
66303bce DH	92	"major=%d minor=%d comm=",
	93	tsk->pid, uid, loginuid, sessionid,
	94	buf->major, buf->minor);
522ed776 MT	95	get_task_comm(name, tsk);
	96	audit_log_untrustedstring(ab, name);
	97	audit_log_format(ab, " data=");
7459b6ff	98	audit_log_n_hex(ab, buf->data, buf->valid);
522ed776 MT	99	audit_log_end(ab);
	100	}
	101	buf->valid = 0;
	102	}
	103
	104	/**
	105	* tty_audit_buf_push_current - Push buffered data out
	106	*
	107	* Generate an audit message from the contents of @buf, which is owned by
	108	* the current task. @buf->mutex must be locked.
	109	*/
	110	static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
	111	{
4746ec5b EP	112	uid_t auid = audit_get_loginuid(current);
	113	unsigned int sessionid = audit_get_sessionid(current);
	114	tty_audit_buf_push(current, auid, sessionid, buf);
522ed776 MT	115	}
	116
	117	/**
	118	* tty_audit_exit - Handle a task exit
	119	*
	120	* Make sure all buffered data is written out and deallocate the buffer.
	121	* Only needs to be called if current->signal->tty_audit_buf != %NULL.
	122	*/
	123	void tty_audit_exit(void)
	124	{
	125	struct tty_audit_buf *buf;
	126
	127	spin_lock_irq(&current->sighand->siglock);
	128	buf = current->signal->tty_audit_buf;
	129	current->signal->tty_audit_buf = NULL;
	130	spin_unlock_irq(&current->sighand->siglock);
	131	if (!buf)
	132	return;
	133
	134	mutex_lock(&buf->mutex);
	135	tty_audit_buf_push_current(buf);
	136	mutex_unlock(&buf->mutex);
	137
	138	tty_audit_buf_put(buf);
	139	}
	140
	141	/**
	142	* tty_audit_fork - Copy TTY audit state for a new task
	143	*
	144	* Set up TTY audit state in @sig from current. @sig needs no locking.
	145	*/
	146	void tty_audit_fork(struct signal_struct *sig)
	147	{
	148	spin_lock_irq(&current->sighand->siglock);
	149	sig->audit_tty = current->signal->audit_tty;
	150	spin_unlock_irq(&current->sighand->siglock);
	151	sig->tty_audit_buf = NULL;
	152	}
	153
	154	/**
	155	* tty_audit_push_task - Flush task's pending audit data
	156	*/
2532386f	157	void tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
522ed776 MT	158	{
	159	struct tty_audit_buf *buf;
	160
	161	spin_lock_irq(&tsk->sighand->siglock);
	162	buf = tsk->signal->tty_audit_buf;
	163	if (buf)
	164	atomic_inc(&buf->count);
	165	spin_unlock_irq(&tsk->sighand->siglock);
	166	if (!buf)
	167	return;
	168
	169	mutex_lock(&buf->mutex);
4746ec5b	170	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
522ed776 MT	171	mutex_unlock(&buf->mutex);
	172
	173	tty_audit_buf_put(buf);
	174	}
	175
	176	/**
	177	* tty_audit_buf_get - Get an audit buffer.
	178	*
	179	* Get an audit buffer for @tty, allocate it if necessary. Return %NULL
	180	* if TTY auditing is disabled or out of memory. Otherwise, return a new
	181	* reference to the buffer.
	182	*/
	183	static struct tty_audit_buf tty_audit_buf_get(struct tty_struct tty)
	184	{
	185	struct tty_audit_buf buf, buf2;
	186
	187	buf = NULL;
	188	buf2 = NULL;
	189	spin_lock_irq(&current->sighand->siglock);
	190	if (likely(!current->signal->audit_tty))
	191	goto out;
	192	buf = current->signal->tty_audit_buf;
	193	if (buf) {
	194	atomic_inc(&buf->count);
	195	goto out;
	196	}
	197	spin_unlock_irq(&current->sighand->siglock);
	198
	199	buf2 = tty_audit_buf_alloc(tty->driver->major,
	200	tty->driver->minor_start + tty->index,
	201	tty->icanon);
	202	if (buf2 == NULL) {
	203	audit_log_lost("out of memory in TTY auditing");
	204	return NULL;
	205	}
	206
	207	spin_lock_irq(&current->sighand->siglock);
	208	if (!current->signal->audit_tty)
	209	goto out;
	210	buf = current->signal->tty_audit_buf;
	211	if (!buf) {
	212	current->signal->tty_audit_buf = buf2;
	213	buf = buf2;
	214	buf2 = NULL;
	215	}
	216	atomic_inc(&buf->count);
	217	/* Fall through */
	218	out:
	219	spin_unlock_irq(&current->sighand->siglock);
	220	if (buf2)
	221	tty_audit_buf_free(buf2);
	222	return buf;
	223	}
	224
	225	/**
	226	* tty_audit_add_data - Add data for TTY auditing.
	227	*
	228	* Audit @data of @size from @tty, if necessary.
	229	*/
	230	void tty_audit_add_data(struct tty_struct tty, unsigned char data,
	231	size_t size)
	232	{
	233	struct tty_audit_buf *buf;
	234	int major, minor;
235
236	if (unlikely(size == 0))
237	return;
238
41126226 MT	239	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
	240	&& tty->driver->subtype == PTY_TYPE_MASTER)
	241	return;
	242
522ed776 MT	243	buf = tty_audit_buf_get(tty);
	244	if (!buf)
	245	return;
	246
	247	mutex_lock(&buf->mutex);
	248	major = tty->driver->major;
	249	minor = tty->driver->minor_start + tty->index;
	250	if (buf->major != major \|\| buf->minor != minor
	251	\|\| buf->icanon != tty->icanon) {
	252	tty_audit_buf_push_current(buf);
	253	buf->major = major;
	254	buf->minor = minor;
	255	buf->icanon = tty->icanon;
	256	}
	257	do {
	258	size_t run;
	259
	260	run = N_TTY_BUF_SIZE - buf->valid;
	261	if (run > size)
	262	run = size;
	263	memcpy(buf->data + buf->valid, data, run);
	264	buf->valid += run;
	265	data += run;
	266	size -= run;
	267	if (buf->valid == N_TTY_BUF_SIZE)
	268	tty_audit_buf_push_current(buf);
	269	} while (size != 0);
	270	mutex_unlock(&buf->mutex);
	271	tty_audit_buf_put(buf);
	272	}
	273
	274	/**
	275	* tty_audit_push - Push buffered data out
	276	*
	277	* Make sure no audit data is pending for @tty on the current process.
	278	*/
	279	void tty_audit_push(struct tty_struct *tty)
	280	{
	281	struct tty_audit_buf *buf;
	282
	283	spin_lock_irq(&current->sighand->siglock);
	284	if (likely(!current->signal->audit_tty)) {
	285	spin_unlock_irq(&current->sighand->siglock);
	286	return;
	287	}
	288	buf = current->signal->tty_audit_buf;
	289	if (buf)
	290	atomic_inc(&buf->count);
	291	spin_unlock_irq(&current->sighand->siglock);
	292
	293	if (buf) {
	294	int major, minor;
	295
	296	major = tty->driver->major;
	297	minor = tty->driver->minor_start + tty->index;
	298	mutex_lock(&buf->mutex);
	299	if (buf->major == major && buf->minor == minor)
	300	tty_audit_buf_push_current(buf);
	301	mutex_unlock(&buf->mutex);
	302	tty_audit_buf_put(buf);
	303	}
	304	}