linux-kernel - Re: [PATCH v2 1/2] seccomp: notify user trap about unused filter

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Message-ID: <202005290058.926E6B5421@keescook>
Date:   Fri, 29 May 2020 01:02:17 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Tycho Andersen <tycho@...ho.ws>,
        Matt Denton <mpdenton@...gle.com>,
        Sargun Dhillon <sargun@...gun.me>,
        Jann Horn <jannh@...gle.com>, Chris Palmer <palmer@...gle.com>,
        Aleksa Sarai <cyphar@...har.com>,
        Robert Sesek <rsesek@...gle.com>,
        Jeffrey Vander Stoep <jeffv@...gle.com>,
        Linux Containers <containers@...ts.linux-foundation.org>
Subject: Re: [PATCH v2 1/2] seccomp: notify user trap about unused filter

On Fri, May 29, 2020 at 09:47:44AM +0200, Christian Brauner wrote:
> Well the correct way would probably be:
> "usage" -> "refs"
> "live"  -> "users"

Yeah, I like it! :)

> So we'd need a first patch to convert "usage" to "refs" and then
> introduce "users".

Yup, sounds right.

> > signal_struct has "sigcnt" and "live". I find "sigcnt" to be an
> > unhelpful name too. (And why isn't it refcount_t?)
> 
> I think I once looked that up and there was some sort of "not needed, no
> gain" style rationale.

hrm. it uses _inc and _dec_and_test... imo, that should make it be a
refcount_t. Even if we're not protecting some clear UAF issue, it's
still good to notification of potential bugs.

-- 
Kees Cook