linux-kernel - Re: [PATCH 1/3] proc: Stop reporting eip and esp in /proc/PID/stat

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Message-ID: <CALCETrWpB=gKpfZWX3O9FvWxxVtw-GrUvyD=f2wOn0tZVLUpCA@mail.gmail.com>
Date:   Fri, 14 Oct 2016 11:25:58 -0700
From:   Andy Lutomirski <luto@...capital.net>
To:     Jann Horn <jann@...jh.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Brian Gerst <brgerst@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Linux API <linux-api@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Tycho Andersen <tycho.andersen@...onical.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Subject: Re: [PATCH 1/3] proc: Stop reporting eip and esp in /proc/PID/stat

On Sat, Oct 1, 2016 at 3:37 AM, Jann Horn <jann@...jh.net> wrote:
> On Fri, Sep 30, 2016 at 07:01:13PM -0700, Andy Lutomirski wrote:
>> On an unrelated note, can we please lock down all the silly historical
>> *userspace* info leaks in /proc?  Nasty ones include: net, cmdline (at
>> the very least, only argv[0] should be visible if the reader lacks
>> ptrace access).
>>
>> Less nasty ones include: limits, sched, autogroup, comm, wchan,
>> schedstat, cpuset, cgroup, oom_*, sessionid, coredump_filter
>
> If that doesn't break stuff, I'm very much in favor of it.
>
>
>> uid_map, gid_map, etc are just screwed up.  They should be per
>> *namespace* somewhere, and they should require creds on the namespace.
>
> What do you have in mind? Something like
> /proc/namespaces/user:123456/{uid_map,gid_map,setgroups,parent_ns},
> with jumped fake symlinks to the directory and its entries in /proc/$pid/?
>

Something along those lines would be nice.

There's an unfortunate tension between having names for namespaces
(like 123456 in your example) for ease of use and *not* having names
so CRIU can restore them more easily.

>
>> timerslack is totally fscked up -- it allows ugo to write and it
>> checks the wrong creds.  Jann, does your series fix that?
>
> Nope. Never noticed that thing so far, probably because it was only
> added a few months ago. :/ Will add it to my series.



-- 
Andy Lutomirski
AMA Capital Management, LLC