[PATCH 6.1 545/609] vt: add permission check for KDSKBMETA ioctl

Greg Kroah-Hartman <[email protected]>
Newsgroups dev.linux.lists.patches,org.kernel.vger.stable
Message-ID <[email protected]>
6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joshua Rogers <[email protected]>

commit a7ad0034453ba4c353f9b8f810ee2569de33d283 upstream.

KDSKBMETA modifies keyboard meta mode but lacks the !perm check that all
other keyboard setter ioctls in vt_k_ioctl() enforce, allowing a process
to change meta mode on a non-controlling console without authorization.

Assisted-by: AISLE:Snapshot
Cc: stable <[email protected]>
Signed-off-by: Joshua Rogers <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/tty/vt/vt_ioctl.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -408,6 +408,8 @@ static int vt_k_ioctl(struct tty_struct
 	/* this could be folded into KDSKBMODE, but for compatibility
 	   reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
 	case KDSKBMETA:
+		if (!perm)
+			return -EPERM;
 		return vt_do_kdskbmeta(console, arg);
 
 	case KDGKBMETA:
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