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@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-14-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 648bdfb..1de0d52 100644 (file)
--- 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,