linux-kernel - Re: [PATCH bpf-next v10 10/10] landlock: Add user and kernel documentation for Landlock

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Message-ID: <08c94f99-68e0-4866-3eba-28fa71347fca@infradead.org>
Date:   Thu, 1 Aug 2019 10:49:05 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Mickaël Salaün <mickael.salaun@....gouv.fr>,
        Mickaël Salaün <mic@...ikod.net>,
        linux-kernel@...r.kernel.org
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Casey Schaufler <casey@...aufler-ca.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        David Drysdale <drysdale@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        James Morris <jmorris@...ei.org>, Jann Horn <jann@...jh.net>,
        John Johansen <john.johansen@...onical.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Paul Moore <paul@...l-moore.com>,
        Sargun Dhillon <sargun@...gun.me>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Shuah Khan <shuah@...nel.org>,
        Stephen Smalley <sds@...ho.nsa.gov>, Tejun Heo <tj@...nel.org>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Thomas Graf <tgraf@...g.ch>, Tycho Andersen <tycho@...ho.ws>,
        Will Drewry <wad@...omium.org>,
        kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        linux-security-module@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v10 10/10] landlock: Add user and kernel
 documentation for Landlock

On 8/1/19 10:03 AM, Mickaël Salaün wrote:
>>> +Ptrace restrictions
>>> +-------------------
>>> +
>>> +A landlocked process has less privileges than a non-landlocked process and must
>>> +then be subject to additional restrictions when manipulating another process.
>>> +To be allowed to use :manpage:`ptrace(2)` and related syscalls on a target
>>> +process, a landlocked process must have a subset of the target process programs.
>>             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> Maybe that last statement is correct, but it seems to me that it is missing something.
> What about this:
> 
> To be allowed to trace a process (using :manpage:`ptrace(2)`), a
> landlocked tracer process must only be constrained by a subset (possibly
> empty) of the Landlock programs which are also applied to the tracee.
> This ensure that the tracer has less or the same constraints than the

       ensures

> tracee, hence protecting against privilege escalation.

Yes, better.  Thanks.


-- 
~Randy