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From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>,
	akpm@linux-foundation.org, jannh@google.com,
	keescook@chromium.org, jeffv@google.com, minchan@kernel.org,
	shakeelb@google.com, rientjes@google.com,
	edgararriaga@google.com, timmurray@google.com,
	linux-mm@kvack.org, selinux@vger.kernel.org,
	linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@android.com
Subject: Re: [PATCH v2 1/1] mm/madvise: replace ptrace attach requirement for process_madvise
Date: Tue, 12 Jan 2021 18:45:08 +0100	[thread overview]
Message-ID: <20210112174507.GA23780@redhat.com> (raw)
In-Reply-To: <20210112074629.GG22493@dhcp22.suse.cz>

On 01/12, Michal Hocko wrote:
>
> On Mon 11-01-21 09:06:22, Suren Baghdasaryan wrote:
>
> > What we want is the ability for one process to influence another process
> > in order to optimize performance across the entire system while leaving
> > the security boundary intact.
> > Replace PTRACE_MODE_ATTACH with a combination of PTRACE_MODE_READ
> > and CAP_SYS_NICE. PTRACE_MODE_READ to prevent leaking ASLR metadata
> > and CAP_SYS_NICE for influencing process performance.
>
> I have to say that ptrace modes are rather obscure to me. So I cannot
> really judge whether MODE_READ is sufficient. My understanding has
> always been that this is requred to RO access to the address space. But
> this operation clearly has a visible side effect. Do we have any actual
> documentation for the existing modes?
>
> I would be really curious to hear from Jann and Oleg (now Cced).

Can't comment, sorry. I never understood these security checks and never tried.
IIUC only selinux/etc can treat ATTACH/READ differently and I have no idea what
is the difference.

Oleg.



  reply	other threads:[~2021-01-12 17:45 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 17:06 [PATCH v2 1/1] mm/madvise: replace ptrace attach requirement for process_madvise Suren Baghdasaryan
2021-01-11 18:33 ` Kees Cook
2021-01-12  1:22 ` Andrew Morton
2021-01-12 17:36   ` Suren Baghdasaryan
2021-01-12  7:46 ` Michal Hocko
2021-01-12 17:45   ` Oleg Nesterov [this message]
2021-01-12 17:51     ` Suren Baghdasaryan
2021-01-13 14:22       ` Michal Hocko
2021-01-13 18:08         ` Suren Baghdasaryan
2021-01-20 13:17         ` Jann Horn
2021-01-20 16:57           ` Suren Baghdasaryan
2021-01-20 20:46             ` Suren Baghdasaryan
2021-01-26 13:52           ` Michal Hocko
2021-01-28 19:51             ` Suren Baghdasaryan
2021-01-29  7:08               ` Suren Baghdasaryan
2021-02-02  5:34                 ` Suren Baghdasaryan
     [not found]                   ` <CAJuCfpEOE8=L1fT4FSauy65cS82M_kW3EzTgH89ewE9HudL=VA@mail.gmail.com>
2021-03-03  0:17                     ` Andrew Morton
2021-03-03  0:19                       ` Suren Baghdasaryan
2021-03-03 19:00                         ` Suren Baghdasaryan
2021-01-12 18:12   ` Suren Baghdasaryan
2021-01-13 14:19     ` Michal Hocko
2021-01-20  5:01 ` James Morris
2021-01-20 16:49   ` Suren Baghdasaryan

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