From: Samuel Thibault samuel.thibault@ens-lyon.org
commit 690c8b804ad2eafbd35da5d3c95ad325ca7d5061 upstream.
83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") broke BRLTTY's ability to simulate keypresses on the console, thus effectively breaking braille keyboards of blind users.
This restores the TIOCSTI feature for CAP_SYS_ADMIN processes, which BRLTTY is, thus fixing braille keyboards without re-opening the security issue.
Signed-off-by: Samuel Thibault samuel.thibault@ens-lyon.org Acked-by: Kees Cook keescook@chromium.org Fixes: 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") Cc: stable@vger.kernel.org Reported-by: Nicolas Pitre nico@fluxnic.net Link: https://lore.kernel.org/r/20230710002645.v565c7xq5iddruse@begin Acked-by: Jiri Slaby jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/tty_io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -2276,7 +2276,7 @@ static int tiocsti(struct tty_struct *tt char ch, mbz = 0; struct tty_ldisc *ld;
- if (!tty_legacy_tiocsti) + if (!tty_legacy_tiocsti && !capable(CAP_SYS_ADMIN)) return -EIO;
if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))