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From: Samuel Thibault <samuel.thibault@ens-lyon.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Simon Brand <simon.brand@postadigitale.de>,
	Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org, Dave@mielke.cc
Subject: [PATCH] TIOCSTI: always enable for CAP_SYS_ADMIN
Date: Mon, 10 Jul 2023 02:26:45 +0200	[thread overview]
Message-ID: <20230710002645.v565c7xq5iddruse@begin> (raw)

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

Index: linux-6.4/drivers/tty/tty_io.c
===================================================================
--- linux-6.4.orig/drivers/tty/tty_io.c
+++ linux-6.4/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))

             reply	other threads:[~2023-07-10  0:26 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-10  0:26 Samuel Thibault [this message]
2023-07-13  6:01 ` [PATCH] TIOCSTI: always enable for CAP_SYS_ADMIN Jiri Slaby
  -- strict thread matches above, loose matches on Subject: below --
2023-07-01 23:59 Samuel Thibault
2023-07-02  0:01 ` kernel test robot
2023-07-03 19:43 ` Kees Cook

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