linux-kernel - [PATCH 14/17] vt: keyboard, union perm checks in vt_do_kdgkb

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Message-Id: <20201029113222.32640-14-jslaby@suse.cz>
Date:   Thu, 29 Oct 2020 12:32:19 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     gregkh@...uxfoundation.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 14/17] vt: keyboard, union perm checks in vt_do_kdgkb_ioctl

Do the permission check on a single place. That is where perm is
really checked.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/tty/vt/keyboard.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 648bdfb05e25..1de0d5217aed 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -2040,9 +2040,6 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 	char *kbs;
 	int ret;
 
-	if (!capable(CAP_SYS_TTY_CONFIG))
-		perm = 0;
-
 	if (get_user(kb_func, &user_kdgkb->kb_func))
 		return -EFAULT;
 
@@ -2067,7 +2064,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm)
 		break;
 	}
 	case KDSKBSENT:
-		if (!perm)
+		if (!perm || !capable(CAP_SYS_TTY_CONFIG))
 			return -EPERM;
 
 		kbs = strndup_user(user_kdgkb->kb_string,
-- 
2.29.1