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SubjectRe: [Security] kernel allows loadkeys to be used by any user, allowing for local root compromise
Horms <horms@verge.net.au> wrote:
>
> drivers/char/vt_ioctl.c: vt_ioctl(): line 377
>
> /*
> * To have permissions to do most of the vt ioctls, we either
> * have
> * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
> */
> perm = 0;
> if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
> perm = 1;
>
>
> A simple fix for this might be just checking for capable(CAP_SYS_TTY_CONFIG)
> in do_kdgkb_ioctl(), which effects KDSKBSENT. This more restrictive
> approach is probably appropriate for many of the other ioctls that set
> VT parameters.

I briefly discussed this with Alan and he agreed that that's a reasonable
approach.

I'll stick the below in -mm, see what breaks.

--- devel/drivers/char/vt_ioctl.c~setkeys-needs-root 2005-10-17 23:50:37.000000000 -0700
+++ devel-akpm/drivers/char/vt_ioctl.c 2005-10-17 23:51:43.000000000 -0700
@@ -192,6 +192,9 @@ do_kdgkb_ioctl(int cmd, struct kbsentry
int i, j, k;
int ret;

+ if (!capable(CAP_SYS_TTY_CONFIG))
+ return -EPERM;
+
kbs = kmalloc(sizeof(*kbs), GFP_KERNEL);
if (!kbs) {
ret = -ENOMEM;
_
-
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