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@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-7-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 c1709b8dbb523f0a87302276969cf82e4448cfb9..823df9bb52b1ded7c1a3d458a15e11314f338018 100644 (file)
--- 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);