Re: [PATCH v2 6/6] KEYS: Verify the key identity in __keyctl_unlink

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, Oct 19, 2026 at 12:35:02PM -0700, Eric Biggers wrote:
> On Mon, Oct 19, 2026 at 09:17:26PM +0300, Jarkko Sakkinen wrote:
> > [PATCH v2 6/6] KEYS: Verify the key identity in __keyctl_unlink
> 
> There is no __keyctl_unlink.  Seems you mean __key_unlink_begin.

This is definitely my typo :-) I was looking at the implementation
in other terminal while writing this and apparently lost focus.

> 
> > Let's define the following preconditions:
> > 
> > - Two keys: A and B.
> > - R is a keyring.
> > - Both have the same type/description/domain.
> > 
> > Then:
> > 
> > 1. KEYCTL_LINK(A, R) => {A}
> > 1. KEYCTL_LINK(B, R) => {B}
> > 2. KEYCTL_UNLINK(A, R) => {}
> 
> Should be 1, 2, and 3?

I tried to describe the scenarion but apparently was not so successful.

I.e. unlinking A removes B given the match in attributes while you would
expect getting -ENOENT and B retained. Or this is the idea.

> 
> > Instead, verify key tidentity before unlinking, and return -ENOENT on
> 
> tidentity => identity
> 
> Also should explicitly say what the bug is.

I tried and failed... But yeah, the bug is illict successful removal
so there is nothing unclear on that side.

Is clearer description enough or should I supplement this keyctl
snippet?

> 
> - Eric

Br, Jarkko