linux-kernel - Re: [PATCH v3 1/2] capability: add cap

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Message-ID: <CAGudoHH-u3KkwSsrSQPGKmhL9uke4HEL8U1Z+aU9etk9-PmdQQ@mail.gmail.com>
Date:   Tue, 28 Feb 2023 22:21:22 +0100
From:   Mateusz Guzik <mjguzik@...il.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Casey Schaufler <casey@...aufler-ca.com>,
        Serge Hallyn <serge@...lyn.com>, viro@...iv.linux.org.uk,
        paul@...l-moore.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [PATCH v3 1/2] capability: add cap_isidentical

On 2/28/23, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> On Tue, Feb 28, 2023 at 11:39 AM Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
>>
>> Call me crazy.
>

Hello crazy,

> I had to go through the patch with a find comb, because everything
> worked except for some reason network name resolution failed:
> systemd-resolved got a permission error on
>
>     Failed to listen on UDP socket 127.0.0.53:53: Permission denied
>
> Spot the insufficient fixup in my cut-and-paste capget() patch:
>
>   kdata[0].effective   = pE.val;
>         kdata[1].effective   = pE.val >> 32;
>   kdata[0].permitted   = pP.val;
>         kdata[1].permitted   = pP.val >> 32;
>   kdata[0].inheritable = pI.val;
>         kdata[0].inheritable = pI.val >> 32;
>
> Oops.
>
> But with that fixed, that patch actually does seem to work.
>

This is part of the crap which made me unwilling to do the clean up.

Unless there is a test suite (which I'm guessing there is not), I
think this warrants a prog which iterates over all methods with a
bunch of randomly generated capsets (+ maybe handpicked corner cases?)
and compares results new vs old. Otherwise I would feel very uneasy
signing off on the patch.

That said, nice cleanup if it works out :)

-- 
Mateusz Guzik <mjguzik gmail.com>