From: Linus Torvalds <torvalds@linux-foundation.org>
To: Djalal Harouni <tixxdz@opendz.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Alexey Dobriyan <adobriyan@gmail.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Vasiliy Kulikov <segoon@openwall.com>,
Kees Cook <keescook@chromium.org>,
Solar Designer <solar@openwall.com>,
WANG Cong <xiyou.wangcong@gmail.com>,
James Morris <james.l.morris@oracle.com>,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Greg KH <gregkh@linuxfoundation.org>, Ingo Molnar <mingo@elte.hu>,
Stephen Wilson <wilsons@start.ca>,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: [PATCH 1/9] exec: add a global execve counter
Date: Sun, 11 Mar 2012 16:42:37 -0700 [thread overview]
Message-ID: <CA+55aFzVZLqnwiXqH4zm6Vn_2QgiRSTDP8uuY3rXyQhobRv63g@mail.gmail.com> (raw)
In-Reply-To: <20120311233233.GC10787@dztty>
On Sun, Mar 11, 2012 at 4:32 PM, Djalal Harouni <tixxdz@opendz.org> wrote:
>>
>> Just increment the mm_count for the thing, and hold a reference to it,
>> and now you're all done.
> Please Linus have you checked the:
> [PATCH 9/9] proc: improve and clean up /proc/<pid>/mem protection
>
> That keeping the mm struct wont work, since it will eat memory and the
> OOM-killer will kill some innocent processes, and the abuse can only be
> catched by the VFS.
That's the point. I made the mistake of using mm_users initially, but
ysing mm_count - which is what I said to use (and what Oleg fixed
things to in commit 6d08f2c71397) should *not* have that problem. It
just keeps the 'struct mm_struct' itself around.
> What's your opinion on it ?
What's the advantage? You replace it with *another* allocation, and a
64-bit thing that is much less useful.
The size of the patch also speaks for itself:
fs/proc/base.c | 99 ++++++++++++++++++++++++++++++++++++++++++++------------
and it's more complex and uses more memory on average (the refcount
thing is *free* for usual cases).
I do agree that it would be nicer if mm_struct was a bit smaller, but
at the same time, I really don't see the advantage of replacing it
with another allocation entirely that makes the code just more
complicated.
Linus
next prev parent reply other threads:[~2012-03-11 23:42 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-10 23:25 [PATCH 0/9] proc: protect /proc/<pid>/* files across execve Djalal Harouni
2012-03-10 23:25 ` [PATCH 1/9] exec: add a global execve counter Djalal Harouni
2012-03-11 0:12 ` Linus Torvalds
2012-03-11 0:36 ` Linus Torvalds
2012-03-11 0:58 ` Linus Torvalds
2012-03-11 8:24 ` Solar Designer
2012-03-11 9:56 ` Ingo Molnar
2012-03-11 14:03 ` Alan Cox
2012-03-11 17:15 ` Djalal Harouni
2012-03-11 8:39 ` Djalal Harouni
2012-03-11 9:40 ` Solar Designer
2012-03-11 17:25 ` Oleg Nesterov
2012-03-11 17:49 ` self_exec_id/parent_exec_id && CLONE_PARENT Oleg Nesterov
2012-03-11 18:02 ` Linus Torvalds
2012-03-11 18:37 ` richard -rw- weinberger
2012-03-11 18:39 ` Oleg Nesterov
2012-03-14 18:55 ` [PATCH 0/1] (Was: self_exec_id/parent_exec_id && CLONE_PARENT) Oleg Nesterov
2012-03-14 18:55 ` [PATCH 1/1] CLONE_PARENT shouldn't allow to set ->exit_signal Oleg Nesterov
2012-03-18 18:25 ` Linus Torvalds
2012-03-18 20:53 ` Oleg Nesterov
2012-03-11 22:48 ` [PATCH 1/9] exec: add a global execve counter Linus Torvalds
2012-03-11 23:32 ` Djalal Harouni
2012-03-11 23:42 ` Linus Torvalds [this message]
2012-03-12 0:25 ` Djalal Harouni
2012-03-12 10:11 ` Linus Torvalds
2012-03-12 14:01 ` Djalal Harouni
2012-03-11 23:36 ` Djalal Harouni
2012-03-12 14:34 ` Oleg Nesterov
2012-03-10 23:25 ` [PATCH 2/9] proc: add proc_file_private struct to store private information Djalal Harouni
2012-03-10 23:25 ` [PATCH 3/9] proc: new proc_exec_id_ok() helper function Djalal Harouni
2012-03-10 23:25 ` [PATCH 4/9] proc: protect /proc/<pid>/* INF files from reader across execve Djalal Harouni
2012-03-10 23:25 ` [PATCH 5/9] proc: add protection support for /proc/<pid>/* ONE files Djalal Harouni
2012-03-10 23:25 ` [PATCH 6/9] proc: protect /proc/<pid>/* ONE files from reader across execve Djalal Harouni
2012-03-10 23:25 ` [PATCH 7/9] proc: protect /proc/<pid>/{maps,smaps,numa_maps} Djalal Harouni
2012-03-10 23:25 ` [PATCH 8/9] proc: protect /proc/<pid>/{environ,pagemap} across execve Djalal Harouni
2012-03-11 8:05 ` Alexey Dobriyan
2012-03-11 17:01 ` Djalal Harouni
2012-03-10 23:25 ` [PATCH 9/9] proc: improve and clean up /proc/<pid>/mem protection Djalal Harouni
2012-03-11 0:01 ` [PATCH 0/9] proc: protect /proc/<pid>/* files across execve Linus Torvalds
2012-03-11 0:27 ` Djalal Harouni
2012-03-11 8:46 ` Djalal Harouni
2012-03-11 10:35 ` exec_id protection from bad child exit signals (was: Re: [PATCH 0/9] proc: protect /proc/<pid>/* files across execve) Solar Designer
2012-03-11 18:20 ` Oleg Nesterov
2012-03-12 19:13 ` [PATCH 0/9] proc: protect /proc/<pid>/* files across execve Eric W. Biederman
2012-03-12 20:44 ` Djalal Harouni
2012-03-12 21:47 ` Eric W. Biederman
2012-03-12 22:41 ` Djalal Harouni
2012-03-12 23:10 ` Eric W. Biederman
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