| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 070/183] tty: Prevent untrappable signals from malicious program | Date | Fri, 6 Mar 2015 09:56:01 +0000 |
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3.16.7-ckt8 -stable review patch. If anyone has any objections, please let me know.
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From: Peter Hurley <peter@hurleysoftware.com>
commit 37480a05685ed5b8e1b9bf5e5c53b5810258b149 upstream.
Commit 26df6d13406d1a5 ("tty: Add EXTPROC support for LINEMODE") allows a process which has opened a pty master to send _any_ signal to the process group of the pty slave. Although potentially exploitable by a malicious program running a setuid program on a pty slave, it's unknown if this exploit currently exists.
Limit to signals actually used.
Cc: Theodore Ts'o <tytso@mit.edu> Cc: Howard Chu <hyc@symas.com> Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/tty/pty.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 25c9bc783722..e49616eeb1cc 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -209,6 +209,9 @@ static int pty_signal(struct tty_struct *tty, int sig) unsigned long flags; struct pid *pgrp; + if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP) + return -EINVAL; + if (tty->link) { spin_lock_irqsave(&tty->link->ctrl_lock, flags); pgrp = get_pid(tty->link->pgrp);
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