tty: allow TIOCSLCKTRMIOS with CAP_CHECKPOINT_RESTORE

The capability CAP_CHECKPOINT_RESTORE was introduced to allow non-root
users to checkpoint and restore processes as non-root with CRIU.

This ch

tty: allow TIOCSLCKTRMIOS with CAP_CHECKPOINT_RESTORE

The capability CAP_CHECKPOINT_RESTORE was introduced to allow non-root
users to checkpoint and restore processes as non-root with CRIU.

This change extends CAP_CHECKPOINT_RESTORE to enable the CRIU option
'--shell-job' as non-root. CRIU's man-page describes the '--shell-job'
option like this:

Allow one to dump shell jobs. This implies the restored task will
inherit session and process group ID from the criu itself. This option
also allows to migrate a single external tty connection, to migrate
applications like top.

TIOCSLCKTRMIOS can only be done if the process has CAP_SYS_ADMIN and
this change extends it to CAP_SYS_ADMIN or CAP_CHECKPOINT_RESTORE.

With this change it is possible to checkpoint and restore processes
which have a tty connection as non-root if CAP_CHECKPOINT_RESTORE is
set.

Acked-by: Christian Brauner <[email protected]>
Signed-off-by: Adrian Reber <[email protected]>
Acked-by: Andrei Vagin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: convert THROTTLE constants into enum

And make an explicit constant for zero too. This allows for easier type
checking of the parameter.

Note: tty_struct::flow_change is kept as int because inc

tty: convert THROTTLE constants into enum

And make an explicit constant for zero too. This allows for easier type
checking of the parameter.

Note: tty_struct::flow_change is kept as int because include/tty.h
(tty_struct) doesn't see tty/tty.h (this enum).

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: fix up and plug in tty_ioctl kernel-doc

The ioctl helpers are well documented, except they are not plugged in
the Documentation. So fix up the minor issues in the kernel-doc and plug
it in.

Th

tty: fix up and plug in tty_ioctl kernel-doc

The ioctl helpers are well documented, except they are not plugged in
the Documentation. So fix up the minor issues in the kernel-doc and plug
it in.

The minor issues include:
* bad \t on every line (sphinx misinterprets the description otherwise)
* missing colon after Return
* superfluous \n after the comment
* make some struct members and constants a hyperlink
* and so on

Perhaps better to use --word-diff if one wants to see the "real"
changes.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: invert return values of tty_{,un}throttle_safe()

If tty_{,un}throttle_safe() returned true on success (similar to
*_trylock()), it would make the conditions in callers more obvious. So
perform

tty: invert return values of tty_{,un}throttle_safe()

If tty_{,un}throttle_safe() returned true on success (similar to
*_trylock()), it would make the conditions in callers more obvious. So
perform the switch to these inverted values (and fix the callers).

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: switch tty_{,un}throttle_safe() to return a bool

They return 0 or 1 -- a boolean value, so make it clear than noone
should expect negative or other values.

Signed-off-by: "Jiri Slaby (SUSE)" <

tty: switch tty_{,un}throttle_safe() to return a bool

They return 0 or 1 -- a boolean value, so make it clear than noone
should expect negative or other values.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: make tty_change_softcar() more understandable

* rename 'arg' to 'enable' as that is what it means.
* make 'bit' a tcflag_t, not int, as that is what cflags are.

Signed-off-by: "Jiri Slaby (SUS

tty: make tty_change_softcar() more understandable

* rename 'arg' to 'enable' as that is what it means.
* make 'bit' a tcflag_t, not int, as that is what cflags are.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: drop tty_debug_wait_until_sent()

It's a nop for everyone as TTY_DEBUG_WAIT_UNTIL_SENT is never set.
Provided, we have better debugging/printout mechanisms nowadays, remove
this mechanism.

Sign

tty: drop tty_debug_wait_until_sent()

It's a nop for everyone as TTY_DEBUG_WAIT_UNTIL_SENT is never set.
Provided, we have better debugging/printout mechanisms nowadays, remove
this mechanism.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: change tty_write_lock()'s ndelay parameter to bool

It's a yes-no parameter, so convert it to bool to be obvious.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.ke

tty: change tty_write_lock()'s ndelay parameter to bool

It's a yes-no parameter, so convert it to bool to be obvious.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH

If userspace races tcsetattr() with a write, the drained condition
might not be guaranteed by the kernel. There is a race window after
che

tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH

If userspace races tcsetattr() with a write, the drained condition
might not be guaranteed by the kernel. There is a race window after
checking Tx is empty before tty_set_termios() takes termios_rwsem for
write. During that race window, more characters can be queued by a
racing writer.

Any ongoing transmission might produce garbage during HW's
->set_termios() call. The intent of TCSADRAIN/FLUSH seems to be
preventing such a character corruption. If those flags are set, take
tty's write lock to stop any writer before performing the lower layer
Tx empty check and wait for the pending characters to be sent (if any).

The initial wait for all-writers-done must be placed outside of tty's
write lock to avoid deadlock which makes it impossible to use
tty_wait_until_sent(). The write lock is retried if a racing write is
detected.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: [email protected]
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty_ioctl: Use BIT() for internal flags

Convert internal flags to use BIT().

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/20230309082035.14880-3-ilpo

tty_ioctl: Use BIT() for internal flags

Convert internal flags to use BIT().

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Return bool from tty_termios_hw_change()

Change tty_termios_hw_change() to return bool.

Reviewed-by: Jiri Slaby <[email protected]>
Reviewed-by: Johan Hovold <[email protected]>
Signed-off-b

tty: Return bool from tty_termios_hw_change()

Change tty_termios_hw_change() to return bool.

Reviewed-by: Jiri Slaby <[email protected]>
Reviewed-by: Johan Hovold <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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termios: start unifying non-UAPI parts of asm/termios.h

* new header (linut/termios_internal.h), pulled by the users of those
suckers
* defaults for INIT_C_CC and externs for conversion helpers move

termios: start unifying non-UAPI parts of asm/termios.h

* new header (linut/termios_internal.h), pulled by the users of those
suckers
* defaults for INIT_C_CC and externs for conversion helpers moved over
there
* remove termios-base.h (empty now)

Signed-off-by: Al Viro <[email protected]>
Link: https://lore.kernel.org/r/YxDmptU7dNGZ+/Hn@ZenIV
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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termios: uninline conversion helpers

default go into drivers/tty/tty_ioctl.c, unusual - into
arch/*/kernel/termios.c (only alpha and sparc have those).

Signed-off-by: Al Viro <[email protected].

termios: uninline conversion helpers

default go into drivers/tty/tty_ioctl.c, unusual - into
arch/*/kernel/termios.c (only alpha and sparc have those).

Signed-off-by: Al Viro <[email protected]>
Link: https://lore.kernel.org/r/YxDmeUBHo0s/Ew8b@ZenIV
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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serial: Make ->set_termios() old ktermios const

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <[email protected]>
Sig

serial: Make ->set_termios() old ktermios const

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: Make tty_termios_copy_hw() old ktermios const

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <[email protected]>

tty: Make tty_termios_copy_hw() old ktermios const

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

serial: Support for RS-485 multipoint addresses

Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().

ADDRB in termios indicate

serial: Support for RS-485 multipoint addresses

Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().

ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.

Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().

[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: remove BOTHER ifdefs

BOTHER is defined by all architectures since commit d0ffb805b729
("arch/alpha, termios: implement BOTHER, IBSHIFT and termios2").

Reviewed-by: Johan Hovold <[email protected]

tty: remove BOTHER ifdefs

BOTHER is defined by all architectures since commit d0ffb805b729
("arch/alpha, termios: implement BOTHER, IBSHIFT and termios2").

Reviewed-by: Johan Hovold <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: remove file from n_tty_ioctl_helper

After the previous patch, there are no users of 'file' in
n_tty_ioctl_helper. So remove it also from there.

Cc: Marcel Holtmann <[email protected]>
Cc: Jo

tty: remove file from n_tty_ioctl_helper

After the previous patch, there are no users of 'file' in
n_tty_ioctl_helper. So remove it also from there.

Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Acked-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: remove file from tty_mode_ioctl

The only user of 'file' parameter in tty_mode_ioctl is a BUG_ON check.
Provided it never crashed for anyone, it's an overkill to pass the
parameter to tty_mode_i

tty: remove file from tty_mode_ioctl

The only user of 'file' parameter in tty_mode_ioctl is a BUG_ON check.
Provided it never crashed for anyone, it's an overkill to pass the
parameter to tty_mode_ioctl only for this check.

If we wanted to check 'file' there, we should handle it in more graceful
way anyway. Not by a BUG == crash.

Cc: Wolfgang Grandegger <[email protected]>
Cc: Marc Kleine-Budde <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Andreas Koensgen <[email protected]>
Cc: Paul Mackerras <[email protected]>
Acked-by: Marc Kleine-Budde <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: make tty_get_{char,frame}_size available

Many tty drivers contain code to compute bits count depending on termios
cflags. So extract this code from serial core to two separate tty helper
functi

tty: make tty_get_{char,frame}_size available

Many tty drivers contain code to compute bits count depending on termios
cflags. So extract this code from serial core to two separate tty helper
functions:
* tty_get_char_size -- only size of a character, without flags,
* tty_get_frame_size -- complete size of a frame including flags.

In the next patch, calls to these new functions replace many copies of
this code.

Note that we accept only cflag as a parameter. That's because some
callers like pch_uart_startup or sunsab_console_setup don't have at hand
termios which we could pass around.

Cc: Joe Perches <[email protected]>
Cc: Johan Hovold <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: remove unused tty_throttle

The last user was removed in commit e91e52e42814 (n_tty: Fix stuck
throttled driver) in 2013. So remove exported tty_throttle completely.

Signed-off-by: Jiri Slaby <

tty: remove unused tty_throttle

The last user was removed in commit e91e52e42814 (n_tty: Fix stuck
throttled driver) in 2013. So remove exported tty_throttle completely.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: make tty_operations::chars_in_buffer return uint

tty_operations::chars_in_buffer is another hook which is expected to
return values >= 0. So make it explicit by the return type too -- use
unsig

tty: make tty_operations::chars_in_buffer return uint

tty_operations::chars_in_buffer is another hook which is expected to
return values >= 0. So make it explicit by the return type too -- use
unsigned int.

Signed-off-by: Jiri Slaby <[email protected]>
Acked-By: Anton Ivanov <[email protected]>
Acked-by: David Sterba <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Samuel Iglesias Gonsalvez <[email protected]>
Cc: Jens Taprogge <[email protected]>
Cc: Karsten Keil <[email protected]>
Cc: Ulf Hansson <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: David Lin <[email protected]>
Cc: Johan Hovold <[email protected]>
Cc: Alex Elder <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Felipe Balbi <[email protected]>
Cc: Mathias Nyman <[email protected]>
Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: make tty_operations::write_room return uint

Line disciplines expect a positive value or zero returned from
tty->ops->write_room (invoked by tty_write_room). So make this
assumption explicit by

tty: make tty_operations::write_room return uint

Line disciplines expect a positive value or zero returned from
tty->ops->write_room (invoked by tty_write_room). So make this
assumption explicit by using unsigned int as a return value. Both of
tty->ops->write_room and tty_write_room.

Signed-off-by: Jiri Slaby <[email protected]>
Acked-by: Laurentiu Tudor <[email protected]>
Acked-by: Alex Elder <[email protected]>
Acked-by: Max Filippov <[email protected]> # xtensa
Acked-by: David Sterba <[email protected]>
Acked-By: Anton Ivanov <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Chris Zankel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Samuel Iglesias Gonsalvez <[email protected]>
Cc: Jens Taprogge <[email protected]>
Cc: Karsten Keil <[email protected]>
Cc: Scott Branden <[email protected]>
Cc: Ulf Hansson <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: David Lin <[email protected]>
Cc: Johan Hovold <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Felipe Balbi <[email protected]>
Cc: Mathias Nyman <[email protected]>
Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: cumulate and document tty_struct::flow* members

Group the flow flags under a single struct called flow. The new struct
contains 'stopped' and 'tco_stopped' bools which used to be bits in a
bitf

tty: cumulate and document tty_struct::flow* members

Group the flow flags under a single struct called flow. The new struct
contains 'stopped' and 'tco_stopped' bools which used to be bits in a
bitfield. The struct also contains the lock protecting them to
potentially share the same cache line.

Note that commit c545b66c6922b (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::unused) is aligned to a 8B boundary too and occupies some
bytes from the next word.

So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.

This is also the perfect time to start the documentation of tty_struct
where all this lives. So we start by documenting what these bools
actually serve for. And why we do all the alignment dances. Only the few
up-to-date information from the Theodore's comment made it into this new
Kerneldoc comment.

Signed-off-by: Jiri Slaby <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Ulf Hansson <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Sascha Hauer <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: "Maciej W. Rozycki" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: move some tty-only functions to drivers/tty/tty.h

The flow change and restricted_tty_write() logic is internal to the tty
core only, so move it out of the include/linux/tty.h file.

Cc: Jiri Sl

tty: move some tty-only functions to drivers/tty/tty.h

The flow change and restricted_tty_write() logic is internal to the tty
core only, so move it out of the include/linux/tty.h file.

Cc: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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