1 files changed, 178 insertions, 176 deletions

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index ce511557b98b..90c70d8d14e3 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -7,6 +7,7 @@
  * discipline handling modules (like SLIP).
  */
 
+#include <linux/bits.h>
 #include <linux/types.h>
 #include <linux/termios.h>
 #include <linux/errno.h>
@@ -27,34 +28,23 @@
 #include <asm/io.h>
 #include <linux/uaccess.h>
 
-#undef TTY_DEBUG_WAIT_UNTIL_SENT
-
-#ifdef TTY_DEBUG_WAIT_UNTIL_SENT
-# define tty_debug_wait_until_sent(tty, f, args...)    tty_debug(tty, f, ##args)
-#else
-# define tty_debug_wait_until_sent(tty, f, args...)    do {} while (0)
-#endif
-
 #undef	DEBUG
 
 /*
  * Internal flag options for termios setting behavior
  */
-#define TERMIOS_FLUSH	1
-#define TERMIOS_WAIT	2
-#define TERMIOS_TERMIO	4
-#define TERMIOS_OLD	8
-
+#define TERMIOS_FLUSH	BIT(0)
+#define TERMIOS_WAIT	BIT(1)
+#define TERMIOS_TERMIO	BIT(2)
+#define TERMIOS_OLD	BIT(3)
 
 /**
- *	tty_chars_in_buffer	-	characters pending
- *	@tty: terminal
+ * tty_chars_in_buffer - characters pending
+ * @tty: terminal
  *
- *	Return the number of bytes of data in the device private
- *	output queue. If no private method is supplied there is assumed
- *	to be no queue on the device.
+ * Returns: the number of bytes of data in the device private output queue. If
+ * no private method is supplied there is assumed to be no queue on the device.
  */
-
 unsigned int tty_chars_in_buffer(struct tty_struct *tty)
 {
 	if (tty->ops->chars_in_buffer)
@@ -64,16 +54,15 @@ unsigned int tty_chars_in_buffer(struct tty_struct *tty)
 EXPORT_SYMBOL(tty_chars_in_buffer);
 
 /**
- *	tty_write_room		-	write queue space
- *	@tty: terminal
+ * tty_write_room - write queue space
+ * @tty: terminal
  *
- *	Return the number of bytes that can be queued to this device
- *	at the present time. The result should be treated as a guarantee
- *	and the driver cannot offer a value it later shrinks by more than
- *	the number of bytes written. If no method is provided 2K is always
- *	returned and data may be lost as there will be no flow control.
+ * Returns: the number of bytes that can be queued to this device at the present
+ * time. The result should be treated as a guarantee and the driver cannot
+ * offer a value it later shrinks by more than the number of bytes written. If
+ * no method is provided, 2K is always returned and data may be lost as there
+ * will be no flow control.
  */
- 
 unsigned int tty_write_room(struct tty_struct *tty)
 {
 	if (tty->ops->write_room)
@@ -83,12 +72,12 @@ unsigned int tty_write_room(struct tty_struct *tty)
 EXPORT_SYMBOL(tty_write_room);
 
 /**
- *	tty_driver_flush_buffer	-	discard internal buffer
- *	@tty: terminal
+ * tty_driver_flush_buffer - discard internal buffer
+ * @tty: terminal
  *
- *	Discard the internal output buffer for this device. If no method
- *	is provided then either the buffer cannot be hardware flushed or
- *	there is no buffer driver side.
+ * Discard the internal output buffer for this device. If no method is provided,
+ * then either the buffer cannot be hardware flushed or there is no buffer
+ * driver side.
  */
 void tty_driver_flush_buffer(struct tty_struct *tty)
 {
@@ -98,107 +87,97 @@ void tty_driver_flush_buffer(struct tty_struct *tty)
 EXPORT_SYMBOL(tty_driver_flush_buffer);
 
 /**
- *	tty_unthrottle		-	flow control
- *	@tty: terminal
+ * tty_unthrottle - flow control
+ * @tty: terminal
  *
- *	Indicate that a tty may continue transmitting data down the stack.
- *	Takes the termios rwsem to protect against parallel throttle/unthrottle
- *	and also to ensure the driver can consistently reference its own
- *	termios data at this point when implementing software flow control.
+ * Indicate that a @tty may continue transmitting data down the stack. Takes
+ * the &tty_struct->termios_rwsem to protect against parallel
+ * throttle/unthrottle and also to ensure the driver can consistently reference
+ * its own termios data at this point when implementing software flow control.
  *
- *	Drivers should however remember that the stack can issue a throttle,
- *	then change flow control method, then unthrottle.
+ * Drivers should however remember that the stack can issue a throttle, then
+ * change flow control method, then unthrottle.
  */
-
 void tty_unthrottle(struct tty_struct *tty)
 {
 	down_write(&tty->termios_rwsem);
 	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
 	    tty->ops->unthrottle)
 		tty->ops->unthrottle(tty);
-	tty->flow_change = 0;
+	tty->flow_change = TTY_FLOW_NO_CHANGE;
 	up_write(&tty->termios_rwsem);
 }
 EXPORT_SYMBOL(tty_unthrottle);
 
 /**
- *	tty_throttle_safe	-	flow control
- *	@tty: terminal
+ * tty_throttle_safe - flow control
+ * @tty: terminal
  *
- *	Indicate that a tty should stop transmitting data down the stack.
- *	tty_throttle_safe will only attempt throttle if tty->flow_change is
- *	TTY_THROTTLE_SAFE. Prevents an accidental throttle due to race
- *	conditions when throttling is conditional on factors evaluated prior to
- *	throttling.
+ * Indicate that a @tty should stop transmitting data down the stack.
+ * tty_throttle_safe() will only attempt throttle if @tty->flow_change is
+ * %TTY_THROTTLE_SAFE. Prevents an accidental throttle due to race conditions
+ * when throttling is conditional on factors evaluated prior to throttling.
  *
- *	Returns 0 if tty is throttled (or was already throttled)
+ * Returns: %true if @tty is throttled (or was already throttled)
  */
-
-int tty_throttle_safe(struct tty_struct *tty)
+bool tty_throttle_safe(struct tty_struct *tty)
 {
-	int ret = 0;
+	guard(mutex)(&tty->throttle_mutex);
 
-	mutex_lock(&tty->throttle_mutex);
-	if (!tty_throttled(tty)) {
-		if (tty->flow_change != TTY_THROTTLE_SAFE)
-			ret = 1;
-		else {
-			set_bit(TTY_THROTTLED, &tty->flags);
-			if (tty->ops->throttle)
-				tty->ops->throttle(tty);
-		}
-	}
-	mutex_unlock(&tty->throttle_mutex);
+	if (tty_throttled(tty))
+		return true;
 
-	return ret;
+	if (tty->flow_change != TTY_THROTTLE_SAFE)
+		return false;
+
+	set_bit(TTY_THROTTLED, &tty->flags);
+	if (tty->ops->throttle)
+		tty->ops->throttle(tty);
+
+	return true;
 }
 
 /**
- *	tty_unthrottle_safe	-	flow control
- *	@tty: terminal
+ * tty_unthrottle_safe - flow control
+ * @tty: terminal
  *
- *	Similar to tty_unthrottle() but will only attempt unthrottle
- *	if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
- *	unthrottle due to race conditions when unthrottling is conditional
- *	on factors evaluated prior to unthrottling.
+ * Similar to tty_unthrottle() but will only attempt unthrottle if
+ * @tty->flow_change is %TTY_UNTHROTTLE_SAFE. Prevents an accidental unthrottle
+ * due to race conditions when unthrottling is conditional on factors evaluated
+ * prior to unthrottling.
  *
- *	Returns 0 if tty is unthrottled (or was already unthrottled)
+ * Returns: %true if @tty is unthrottled (or was already unthrottled)
  */
-
-int tty_unthrottle_safe(struct tty_struct *tty)
+bool tty_unthrottle_safe(struct tty_struct *tty)
 {
-	int ret = 0;
+	guard(mutex)(&tty->throttle_mutex);
 
-	mutex_lock(&tty->throttle_mutex);
-	if (tty_throttled(tty)) {
-		if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
-			ret = 1;
-		else {
-			clear_bit(TTY_THROTTLED, &tty->flags);
-			if (tty->ops->unthrottle)
-				tty->ops->unthrottle(tty);
-		}
-	}
-	mutex_unlock(&tty->throttle_mutex);
+	if (!tty_throttled(tty))
+		return true;
 
-	return ret;
+	if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
+		return false;
+
+	clear_bit(TTY_THROTTLED, &tty->flags);
+	if (tty->ops->unthrottle)
+		tty->ops->unthrottle(tty);
+
+	return true;
 }
 
 /**
- *	tty_wait_until_sent	-	wait for I/O to finish
- *	@tty: tty we are waiting for
- *	@timeout: how long we will wait
+ * tty_wait_until_sent - wait for I/O to finish
+ * @tty: tty we are waiting for
+ * @timeout: how long we will wait
  *
- *	Wait for characters pending in a tty driver to hit the wire, or
- *	for a timeout to occur (eg due to flow control)
+ * Wait for characters pending in a tty driver to hit the wire, or for a
+ * timeout to occur (eg due to flow control).
  *
- *	Locking: none
+ * Locking: none
  */
 
 void tty_wait_until_sent(struct tty_struct *tty, long timeout)
 {
-	tty_debug_wait_until_sent(tty, "wait until sent, timeout=%ld\n", timeout);
-
 	if (!timeout)
 		timeout = MAX_SCHEDULE_TIMEOUT;
 
@@ -240,16 +219,15 @@ static void unset_locked_termios(struct tty_struct *tty, const struct ktermios *
 }
 
 /**
- *	tty_termios_copy_hw	-	copy hardware settings
- *	@new: New termios
- *	@old: Old termios
+ * tty_termios_copy_hw - copy hardware settings
+ * @new: new termios
+ * @old: old termios
  *
- *	Propagate the hardware specific terminal setting bits from
- *	the old termios structure to the new one. This is used in cases
- *	where the hardware does not support reconfiguration or as a helper
- *	in some cases where only minimal reconfiguration is supported
+ * Propagate the hardware specific terminal setting bits from the @old termios
+ * structure to the @new one. This is used in cases where the hardware does not
+ * support reconfiguration or as a helper in some cases where only minimal
+ * reconfiguration is supported.
  */
-
 void tty_termios_copy_hw(struct ktermios *new, const struct ktermios *old)
 {
 	/* The bits a dumb device handles in software. Smart devices need
@@ -262,30 +240,30 @@ void tty_termios_copy_hw(struct ktermios *new, const struct ktermios *old)
 EXPORT_SYMBOL(tty_termios_copy_hw);
 
 /**
- *	tty_termios_hw_change	-	check for setting change
- *	@a: termios
- *	@b: termios to compare
+ * tty_termios_hw_change - check for setting change
+ * @a: termios
+ * @b: termios to compare
  *
- *	Check if any of the bits that affect a dumb device have changed
- *	between the two termios structures, or a speed change is needed.
+ * Check if any of the bits that affect a dumb device have changed between the
+ * two termios structures, or a speed change is needed.
+ *
+ * Returns: %true if change is needed
  */
-
-int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
+bool tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
 {
 	if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed)
-		return 1;
+		return true;
 	if ((a->c_cflag ^ b->c_cflag) & ~(HUPCL | CREAD | CLOCAL))
-		return 1;
-	return 0;
+		return true;
+	return false;
 }
 EXPORT_SYMBOL(tty_termios_hw_change);
 
 /**
- *	tty_get_char_size	-	get size of a character
- *	@cflag: termios cflag value
+ * tty_get_char_size - get size of a character
+ * @cflag: termios cflag value
  *
- *	Get the size (in bits) of a character depending on @cflag's %CSIZE
- *	setting.
+ * Returns: size (in bits) of a character depending on @cflag's %CSIZE setting
  */
 unsigned char tty_get_char_size(unsigned int cflag)
 {
@@ -304,13 +282,14 @@ unsigned char tty_get_char_size(unsigned int cflag)
 EXPORT_SYMBOL_GPL(tty_get_char_size);
 
 /**
- *	tty_get_frame_size	-	get size of a frame
- *	@cflag: termios cflag value
+ * tty_get_frame_size - get size of a frame
+ * @cflag: termios cflag value
  *
- *	Get the size (in bits) of a frame depending on @cflag's %CSIZE, %CSTOPB,
- *	and %PARENB setting. The result is a sum of character size, start and
- *	stop bits -- one bit each -- second stop bit (if set), and parity bit
- *	(if set).
+ * Get the size (in bits) of a frame depending on @cflag's %CSIZE, %CSTOPB, and
+ * %PARENB setting. The result is a sum of character size, start and stop bits
+ * -- one bit each -- second stop bit (if set), and parity bit (if set).
+ *
+ * Returns: size (in bits) of a frame depending on @cflag's setting.
  */
 unsigned char tty_get_frame_size(unsigned int cflag)
 {
@@ -328,16 +307,15 @@ unsigned char tty_get_frame_size(unsigned int cflag)
 EXPORT_SYMBOL_GPL(tty_get_frame_size);
 
 /**
- *	tty_set_termios		-	update termios values
- *	@tty: tty to update
- *	@new_termios: desired new value
+ * tty_set_termios - update termios values
+ * @tty: tty to update
+ * @new_termios: desired new value
  *
- *	Perform updates to the termios values set on this terminal.
- *	A master pty's termios should never be set.
+ * Perform updates to the termios values set on this @tty. A master pty's
+ * termios should never be set.
  *
- *	Locking: termios_rwsem
+ * Locking: &tty_struct->termios_rwsem
  */
-
 int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
 {
 	struct ktermios old_termios;
@@ -450,18 +428,19 @@ __weak int kernel_termios_to_user_termios(struct termios __user *u,
 #endif /* TCGETS2 */
 
 /**
- *	set_termios		-	set termios values for a tty
- *	@tty: terminal device
- *	@arg: user data
- *	@opt: option information
+ * set_termios - set termios values for a tty
+ * @tty: terminal device
+ * @arg: user data
+ * @opt: option information
  *
- *	Helper function to prepare termios data and run necessary other
- *	functions before using tty_set_termios to do the actual changes.
+ * Helper function to prepare termios data and run necessary other functions
+ * before using tty_set_termios() to do the actual changes.
  *
- *	Locking:
- *		Called functions take ldisc and termios_rwsem locks
+ * Locking: called functions take &tty_struct->ldisc_sem and
+ * &tty_struct->termios_rwsem locks
+ *
+ * Returns: 0 on success, an error otherwise
  */
-
 static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
 {
 	struct ktermios tmp_termios;
@@ -500,21 +479,42 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
 	tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
 	tmp_termios.c_ospeed = tty_termios_baud_rate(&tmp_termios);
 
-	ld = tty_ldisc_ref(tty);
+	if (opt & (TERMIOS_FLUSH|TERMIOS_WAIT)) {
+retry_write_wait:
+		retval = wait_event_interruptible(tty->write_wait, !tty_chars_in_buffer(tty));
+		if (retval < 0)
+			return retval;
 
-	if (ld != NULL) {
-		if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
-			ld->ops->flush_buffer(tty);
-		tty_ldisc_deref(ld);
-	}
+		if (tty_write_lock(tty, false) < 0)
+			goto retry_write_wait;
 
-	if (opt & TERMIOS_WAIT) {
-		tty_wait_until_sent(tty, 0);
-		if (signal_pending(current))
-			return -ERESTARTSYS;
-	}
+		/* Racing writer? */
+		if (tty_chars_in_buffer(tty)) {
+			tty_write_unlock(tty);
+			goto retry_write_wait;
+		}
+
+		ld = tty_ldisc_ref(tty);
+		if (ld != NULL) {
+			if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
+				ld->ops->flush_buffer(tty);
+			tty_ldisc_deref(ld);
+		}
+
+		if ((opt & TERMIOS_WAIT) && tty->ops->wait_until_sent) {
+			tty->ops->wait_until_sent(tty, 0);
+			if (signal_pending(current)) {
+				tty_write_unlock(tty);
+				return -ERESTARTSYS;
+			}
+		}
 
-	tty_set_termios(tty, &tmp_termios);
+		tty_set_termios(tty, &tmp_termios);
+
+		tty_write_unlock(tty);
+	} else {
+		tty_set_termios(tty, &tmp_termios);
+	}
 
 	/* FIXME: Arguably if tmp_termios == tty->termios AND the
 	   actual requested termios was not tmp_termios then we may
@@ -612,16 +612,16 @@ static void set_sgflags(struct ktermios *termios, int flags)
 }
 
 /**
- *	set_sgttyb		-	set legacy terminal values
- *	@tty: tty structure
- *	@sgttyb: pointer to old style terminal structure
+ * set_sgttyb - set legacy terminal values
+ * @tty: tty structure
+ * @sgttyb: pointer to old style terminal structure
  *
- *	Updates a terminal from the legacy BSD style terminal information
- *	structure.
+ * Updates a terminal from the legacy BSD style terminal information structure.
  *
- *	Locking: termios_rwsem
+ * Locking: &tty_struct->termios_rwsem
+ *
+ * Returns: 0 on success, an error otherwise
  */
-
 static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
 {
 	int retval;
@@ -723,19 +723,22 @@ static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
 #endif
 
 /**
- *	tty_change_softcar	-	carrier change ioctl helper
- *	@tty: tty to update
- *	@arg: enable/disable CLOCAL
+ * tty_change_softcar - carrier change ioctl helper
+ * @tty: tty to update
+ * @enable: enable/disable %CLOCAL
+ *
+ * Perform a change to the %CLOCAL state and call into the driver layer to make
+ * it visible.
  *
- *	Perform a change to the CLOCAL state and call into the driver
- *	layer to make it visible. All done with the termios rwsem
+ * Locking: &tty_struct->termios_rwsem.
+ *
+ * Returns: 0 on success, an error otherwise
  */
-
-static int tty_change_softcar(struct tty_struct *tty, int arg)
+static int tty_change_softcar(struct tty_struct *tty, bool enable)
 {
 	int ret = 0;
-	int bit = arg ? CLOCAL : 0;
 	struct ktermios old;
+	tcflag_t bit = enable ? CLOCAL : 0;
 
 	down_write(&tty->termios_rwsem);
 	old = tty->termios;
@@ -750,16 +753,15 @@ static int tty_change_softcar(struct tty_struct *tty, int arg)
 }
 
 /**
- *	tty_mode_ioctl		-	mode related ioctls
- *	@tty: tty for the ioctl
- *	@cmd: command
- *	@arg: ioctl argument
+ * tty_mode_ioctl - mode related ioctls
+ * @tty: tty for the ioctl
+ * @cmd: command
+ * @arg: ioctl argument
  *
- *	Perform non line discipline specific mode control ioctls. This
- *	is designed to be called by line disciplines to ensure they provide
- *	consistent mode setting.
+ * Perform non-line discipline specific mode control ioctls. This is designed
+ * to be called by line disciplines to ensure they provide consistent mode
+ * setting.
  */
-
 int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 {
 	struct tty_struct *real_tty;
@@ -838,7 +840,7 @@ int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 			ret = -EFAULT;
 		return ret;
 	case TIOCSLCKTRMIOS:
-		if (!capable(CAP_SYS_ADMIN))
+		if (!checkpoint_restore_ns_capable(&init_user_ns))
 			return -EPERM;
 		copy_termios_locked(real_tty, &kterm);
 		if (user_termios_to_kernel_termios(&kterm,
@@ -855,7 +857,7 @@ int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 			ret = -EFAULT;
 		return ret;
 	case TIOCSLCKTRMIOS:
-		if (!capable(CAP_SYS_ADMIN))
+		if (!checkpoint_restore_ns_capable(&init_user_ns))
 			return -EPERM;
 		copy_termios_locked(real_tty, &kterm);
 		if (user_termios_to_kernel_termios_1(&kterm,