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Message-Id: <20170417060706.28674-4-matt@nmatt.com>
Date: Mon, 17 Apr 2017 02:07:05 -0400
From: Matt Brown <matt@...tt.com>
To: jmorris@...ei.org,
gregkh@...uxfoundation.org,
akpm@...ux-foundation.org
Cc: linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Matt Brown <matt@...tt.com>
Subject: [PATCH 3/4] restrict unprivileged TIOCSTI tty ioctl
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@...tt.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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