linux-kernel - Re: [PATCH] keys: Allow disabling read permissions for key possessor

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Message-ID: <YFlMJ12+3/MpYixW@kernel.org>
Date:   Tue, 23 Mar 2021 04:02:15 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Andrey Ryabinin <arbn@...dex-team.ru>,
        David Howells <dhowells@...hat.com>
Cc:     James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] keys: Allow disabling read permissions for key possessor

On Mon, Mar 22, 2021 at 12:57:26PM +0300, Andrey Ryabinin wrote:
> keyctl_read_key() has a strange code which allows possessor to read
> key's payload regardless of READ permission status:
> 
> $ keyctl add user test test @u
> 196773443
> $ keyctl print 196773443
> test
> $ keyctl describe 196773443
> 196773443: alswrv-----v------------  1000  1000 user: test
> $ keyctl rdescribe 196773443
> user;1000;1000;3f010000;test
> $ keyctl setperm 196773443 0x3d010000
> $ keyctl describe 196773443
> 196773443: alsw-v-----v------------  1000  1000 user: test
> $ keyctl  print 196773443
> test
> 
> The last keyctl print should fail with -EACCESS instead of success.
> Fix this by removing weird possessor checks.
> 
> Signed-off-by: Andrey Ryabinin <arbn@...dex-team.ru>

I wrote a new test. If you include a test into a commit please
describe it so that it can be easily executed. Otherwise, it is
somewhat useless.

Anyway,

https://gist.github.com/jarkk0sakkinen/7b417be20cb52ed971a90561192f0883

David, why all of these end up allowing to still print the payload?

/Jarkko