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Subject: Re: [PATCH bpf-next v10 10/10] landlock: Add user and kernel
 documentation for Landlock
To:     =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= <mickael.salaun@ssi.gouv.fr>,
        =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= <mic@digikod.net>,
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Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Casey Schaufler <casey@schaufler-ca.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        David Drysdale <drysdale@google.com>,
        "David S . Miller" <davem@davemloft.net>,
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        Michael Kerrisk <mtk.manpages@gmail.com>,
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        Sargun Dhillon <sargun@sargun.me>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        Shuah Khan <shuah@kernel.org>,
        Stephen Smalley <sds@tycho.nsa.gov>, Tejun Heo <tj@kernel.org>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
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        linux-fsdevel@vger.kernel.org,
        linux-security-module@vger.kernel.org, netdev@vger.kernel.org
References: <20190721213116.23476-1-mic@digikod.net>
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From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <08c94f99-68e0-4866-3eba-28fa71347fca@infradead.org>
Date:   Thu, 1 Aug 2019 10:49:05 -0700
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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