From: Michal Hocko <mhocko@suse.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Jann Horn" <jannh@google.com>,
"Kees Cook" <keescook@chromium.org>,
"Jeffrey Vander Stoep" <jeffv@google.com>,
"Minchan Kim" <minchan@kernel.org>,
"Shakeel Butt" <shakeelb@google.com>,
"David Rientjes" <rientjes@google.com>,
"Edgar Arriaga García" <edgararriaga@google.com>,
"Tim Murray" <timmurray@google.com>,
linux-mm <linux-mm@kvack.org>,
selinux@vger.kernel.org, "Linux API" <linux-api@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-team <kernel-team@android.com>,
"Oleg Nesterov" <oleg@redhat.com>
Subject: Re: [PATCH v2 1/1] mm/madvise: replace ptrace attach requirement for process_madvise
Date: Wed, 13 Jan 2021 15:19:32 +0100 [thread overview]
Message-ID: <20210113141932.GB22493@dhcp22.suse.cz> (raw)
In-Reply-To: <CAJuCfpHazLXJ1rpJQ+w9=8-O==rzz3yEVuVtSn-sYMS+a3FoXQ@mail.gmail.com>
On Tue 12-01-21 10:12:03, Suren Baghdasaryan wrote:
> On Mon, Jan 11, 2021 at 11:46 PM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Mon 11-01-21 09:06:22, Suren Baghdasaryan wrote:
> > > process_madvise currently requires ptrace attach capability.
> > > PTRACE_MODE_ATTACH gives one process complete control over another
> > > process. It effectively removes the security boundary between the
> > > two processes (in one direction). Granting ptrace attach capability
> > > even to a system process is considered dangerous since it creates an
> > > attack surface. This severely limits the usage of this API.
> > > The operations process_madvise can perform do not affect the correctness
> > > of the operation of the target process; they only affect where the data
> > > is physically located (and therefore, how fast it can be accessed).
> >
> > Yes it doesn't influence the correctness but it is still a very
> > sensitive operation because it can allow a targeted side channel timing
> > attacks so we should be really careful.
>
> Sorry, I missed this comment in my answer. Possibility of affecting
> the target's performance including side channel attack is why we
> require CAP_SYS_NICE.
OK. It would be really good to document that in the man page. From the
current wording it seems we already rely on this cap for migration on a
remote process which is not the same thing but it roughly falls into the
similar category.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-01-13 14:20 UTC|newest]
Thread overview: 24+ 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
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
2021-03-02 23:53 ` Suren Baghdasaryan
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 [this message]
2021-01-20 5:01 ` James Morris
2021-01-20 16:49 ` Suren Baghdasaryan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210113141932.GB22493@dhcp22.suse.cz \
--to=mhocko@suse.com \
--cc=akpm@linux-foundation.org \
--cc=edgararriaga@google.com \
--cc=jannh@google.com \
--cc=jeffv@google.com \
--cc=keescook@chromium.org \
--cc=kernel-team@android.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=minchan@kernel.org \
--cc=oleg@redhat.com \
--cc=rientjes@google.com \
--cc=selinux@vger.kernel.org \
--cc=shakeelb@google.com \
--cc=surenb@google.com \
--cc=timmurray@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).