linux-kernel - Re: [PATCH] KEYS: prevent creating a different user's keyrings

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Message-ID: <29684.1505837120@warthog.procyon.org.uk>
Date:   Tue, 19 Sep 2017 17:05:20 +0100
From:   David Howells <dhowells@...hat.com>
To:     Eric Biggers <ebiggers3@...il.com>
Cc:     dhowells@...hat.com, keyrings@...r.kernel.org,
        Michael Halcrow <mhalcrow@...gle.com>,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH] KEYS: prevent creating a different user's keyrings

Eric Biggers <ebiggers3@...il.com> wrote:

> Fix it by marking user and user session keyrings with a flag
> KEY_FLAG_UID_KEYRING.  Then, when searching for a user or user session
> keyring by name, skip all keyrings that don't have the flag set.

I wonder if it's better just to reject attempts to manually create/join
keyrings of such names.  PAM uses the implicit creation method of specifying
the 'macro' key IDs for these keyrings.

David