kernel/linux.git/drivers/tty/tty_ioctl.c, branch v6.19.11

tty: simplify throttling using guard()s

2025-04-25T11:46:30+00:00

tty_throttle_safe() and tty_unthrottle_safe can be made less convoluted using guard()s. Switch them. Signed-off-by: Jiri Slaby (SUSE) Link: https://lore.kernel.org/r/20250425111315.1036184-2-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: allow TIOCSLCKTRMIOS with CAP_CHECKPOINT_RESTORE

2023-12-15T13:20:03+00:00

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 Signed-off-by: Adrian Reber Acked-by: Andrei Vagin Link: https://lore.kernel.org/r/20231208143656.1019-1-areber@redhat.com Signed-off-by: Greg Kroah-Hartman

tty: convert THROTTLE constants into enum

2023-10-03T12:31:16+00:00

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)" Link: https://lore.kernel.org/r/20230919085156.1578-13-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: fix up and plug in tty_ioctl kernel-doc

2023-10-03T12:31:15+00:00

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)" Link: https://lore.kernel.org/r/20230919085156.1578-9-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

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

2023-10-03T12:31:15+00:00

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)" Link: https://lore.kernel.org/r/20230919085156.1578-8-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

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

2023-10-03T12:31:15+00:00

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)" Link: https://lore.kernel.org/r/20230919085156.1578-7-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: make tty_change_softcar() more understandable

2023-08-11T19:12:44+00:00

* 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)" Link: https://lore.kernel.org/r/20230810091510.13006-9-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: drop tty_debug_wait_until_sent()

2023-08-11T19:12:44+00:00

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)" Link: https://lore.kernel.org/r/20230810091510.13006-8-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

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

2023-08-11T19:12:44+00:00

It's a yes-no parameter, so convert it to bool to be obvious. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230810091510.13006-6-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH

2023-03-29T08:55:53+00:00

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: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230317113318.31327-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman