linux-kernel - Re: [REVIEW][PATCH 2/3] ptrace: Don't allow accessing an undumpable mm

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Message-ID: <CAGXu5jKq9yKL16U2v8uzZt=kCa2U9JF8y4yUEpc5VgWXQghyWA@mail.gmail.com>
Date:   Thu, 17 Nov 2016 15:17:27 -0800
From:   Kees Cook <keescook@...omium.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Willy Tarreau <w@....eu>,
        Linux Containers <containers@...ts.linux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Michal Hocko <mhocko@...nel.org>, Jann Horn <jann@...jh.net>,
        Andy Lutomirski <luto@...capital.net>
Subject: Re: [REVIEW][PATCH 2/3] ptrace: Don't allow accessing an undumpable mm

On Thu, Nov 17, 2016 at 2:50 PM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
>
> It is the reasonable expectation that if an executable file is not
> readable there will be no way for a user without special privileges to
> read the file.  This is enforced in ptrace_attach but if ptrace
> is already attached before exec there is no enforcement for read-only
> executables.

Given the corner cases being fixed here, it might make sense to add
some simple tests to tools/testing/sefltests/ptrace/ to validate these
changes and avoid future regressions.

Regardless, it'll be nice to have this fixed. :)

-Kees

-- 
Kees Cook
Nexus Security