/* * 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; 	buf = current->signal->tty_audit_buf;	current->signal->tty_audit_buf = NULL;	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){	sig->audit_tty = current->signal->audit_tty;	sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd;} /** *	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;	int audit_log_tty_passwd;	unsigned long flags; 	if (unlikely(size == 0))		return; 	spin_lock_irqsave(&current->sighand->siglock, flags);	audit_log_tty_passwd = current->signal->audit_tty_log_passwd;	spin_unlock_irqrestore(&current->sighand->siglock, flags);	if (!audit_log_tty_passwd && icanon && !L_ECHO(tty))		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);	}}