linux-kernel - [PATCH 07/17] vt: keyboard, union perm checks in vt_do_kdsk

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Message-Id: <20201029113222.32640-7-jslaby@suse.cz>
Date:   Thu, 29 Oct 2020 12:32:12 +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 07/17] vt: keyboard, union perm checks in vt_do_kdsk_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 c1709b8dbb52..823df9bb52b1 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -2004,16 +2004,13 @@ int vt_do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm,
 	if (copy_from_user(&kbe, user_kbe, sizeof(struct kbentry)))
 		return -EFAULT;
 
-	if (!capable(CAP_SYS_TTY_CONFIG))
-		perm = 0;
-
 	switch (cmd) {
 	case KDGKBENT:
 		return put_user(vt_kdgkbent(kb->kbdmode, kbe.kb_index,
 					kbe.kb_table),
 				&user_kbe->kb_value);
 	case KDSKBENT:
-		if (!perm)
+		if (!perm || !capable(CAP_SYS_TTY_CONFIG))
 			return -EPERM;
 		return vt_kdskbent(kb->kbdmode, kbe.kb_index, kbe.kb_table,
 				kbe.kb_value);
-- 
2.29.1