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Groups > linux.kernel > #1624558

[PATCH 3/4] restrict unprivileged TIOCSTI tty ioctl

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this patch depends on patch 1 and 2

enforces restrictions on unprivileged users injecting commands
into other processes in the same tty session using the TIOCSTI ioctl

Signed-off-by: Matt Brown <matt@nmatt.com>
---
 drivers/tty/tty_io.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e6d1a65..31894e8 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2296,11 +2296,15 @@ static int tty_fasync(int fd, struct file *filp, int on)
  *	FIXME: may race normal receive processing
  */
 
+int tiocsti_restrict = IS_ENABLED(CONFIG_SECURITY_TIOCSTI_RESTRICT);
+
 static int tiocsti(struct tty_struct *tty, char __user *p)
 {
 	char ch, mbz = 0;
 	struct tty_ldisc *ld;
 
+	if (tiocsti_restrict && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
 	if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
 		return -EPERM;
 	if (get_user(ch, p))
-- 
2.10.2

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Patchset to Restrict Unprivileged TIOCSTI TTY Command Injection Matt Brown <matt@nmatt.com> - 2017-04-17 08:10 +0200
  [PATCH 3/4] restrict unprivileged TIOCSTI tty ioctl Matt Brown <matt@nmatt.com> - 2017-04-17 08:10 +0200
    Re: [PATCH 3/4] restrict unprivileged TIOCSTI tty ioctl Greg KH <gregkh@linuxfoundation.org> - 2017-04-17 09:00 +0200
      Re: [kernel-hardening] Re: [PATCH 3/4] restrict unprivileged TIOCSTI  tty ioctl Jann Horn <jannh@google.com> - 2017-04-17 16:20 +0200
        Re: [kernel-hardening] Re: [PATCH 3/4] restrict unprivileged TIOCSTI  tty ioctl Matt Brown <matt@nmatt.com> - 2017-04-17 18:30 +0200

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