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From: "Mickaël Salaün" <firstname.lastname@example.org>
To: Pavel Machek <email@example.com>
Cc: "Madhavan T. Venkataraman" <firstname.lastname@example.org>,
email@example.com, firstname.lastname@example.org, David.Laight@ACULAB.COM,
Subject: Re: [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor
Date: Fri, 25 Sep 2020 12:12:01 +0200 [thread overview]
Message-ID: <email@example.com> (raw)
On 25/09/2020 00:05, Pavel Machek wrote:
>>>>> I believe you should simply delete confusing "introduction" and
>>>>> provide details of super-secure system where your patches would be
>>>>> useful, instead.
>>>> This RFC talks about converting dynamic code (which cannot be authenticated)
>>>> to static code that can be authenticated using signature verification. That
>>>> is the scope of this RFC.
>>>> If I have not been clear before, by dynamic code, I mean machine code that is
>>>> dynamic in nature. Scripts are beyond the scope of this RFC.
>>>> Also, malware compiled from sources is not dynamic code. That is orthogonal
>>>> to this RFC. If such malware has a valid signature that the kernel permits its
>>>> execution, we have a systemic problem.
>>>> I am not saying that script authentication or compiled malware are not problems.
>>>> I am just saying that this RFC is not trying to solve all of the security problems.
>>>> It is trying to define one way to convert dynamic code to static code to address
>>>> one class of problems.
>>> Well, you don't have to solve all problems at once.
>>> But solutions have to exist, and AFAIK in this case they don't. You
>>> are armoring doors, but ignoring open windows.
>> FYI, script execution is being addressed (for the kernel part) by this
>> patch series:
>>> Or very probably you are thinking about something different than
>>> normal desktop distros (Debian 10). Because on my systems, I have
>>> python, gdb and gcc...
>> It doesn't make sense for a tailored security system to leave all these
>> tools available to an attacker.
> And it also does not make sense to use "trampoline file descriptor" on
> generic system... while W^X should make sense there.
Well, as said before, (full/original/system-wide) W^X may require
trampfd (as well as other building-blocks).
I guess most Linux deployments are not on "generic systems"
anyway (even if they may be based on generic distros), and W^X
contradicts the fact that users/attackers can do whatever they want on
>>> It would be nice to specify what other pieces need to be present for
>>> this to make sense -- because it makes no sense on Debian 10.
>> Not all kernel features make sense for a generic/undefined usage,
>> especially specific security mechanisms (e.g. SELinux, Smack, Tomoyo,
>> SafeSetID, LoadPin, IMA, IPE, secure/trusted boot, lockdown, etc.), but
>> they can still be definitely useful.
> Yep... so... I'd expect something like... "so you have single-purpose
No one talked about a single-purpose system.
> with all script interpreters removed,
Not necessarily with the patch series I pointed out just before.
> IMA hashing all the files
> to make sure they are not modified, and W^X enabled.
System-wide W^X is not only for memory, and as Madhavan said: "this RFC
pertains to converting dynamic [writable] machine code to static
> Attacker can
> still execute code after buffer overflow by .... and trapoline file
> descriptor addrsses that"... so that people running generic systems
> can stop reading after first sentence.
Are you proposing to add a
"[feature-not-useful-without-a-proper-system-configuration]" tag in
prev parent reply other threads:[~2020-09-25 10:18 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <210d7cd762d5307c2aa1676705b392bd445f1baa>
2020-09-16 15:08 ` madvenka
2020-09-16 15:08 ` [PATCH v2 1/4] [RFC] fs/trampfd: Implement the trampoline file descriptor API madvenka
2020-09-16 15:08 ` [PATCH v2 2/4] [RFC] x86/trampfd: Provide support for the trampoline file descriptor madvenka
2020-09-16 15:08 ` [PATCH v2 3/4] [RFC] arm64/trampfd: " madvenka
2020-09-16 15:08 ` [PATCH v2 4/4] [RFC] arm/trampfd: " madvenka
2020-09-17 1:04 ` [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor Florian Weimer
2020-09-17 15:36 ` Madhavan T. Venkataraman
2020-09-17 15:57 ` Madhavan T. Venkataraman
2020-09-17 16:01 ` Florian Weimer
2020-09-23 1:46 ` Arvind Sankar
2020-09-23 9:11 ` Arvind Sankar
2020-09-23 19:17 ` Madhavan T. Venkataraman
2020-09-23 19:51 ` Arvind Sankar
2020-09-23 23:51 ` Madhavan T. Venkataraman
2020-09-24 20:23 ` Madhavan T. Venkataraman
2020-09-24 20:52 ` Florian Weimer
2020-09-25 22:22 ` Madhavan T. Venkataraman
2020-09-27 18:25 ` Madhavan T. Venkataraman
2020-09-24 22:13 ` Pavel Machek
2020-09-24 23:43 ` Arvind Sankar
2020-09-25 22:44 ` Madhavan T. Venkataraman
2020-09-26 15:55 ` Arvind Sankar
2020-09-27 17:59 ` Madhavan T. Venkataraman
2020-09-22 21:53 ` madvenka
2020-09-22 21:53 ` [PATCH v2 1/4] [RFC] fs/trampfd: Implement the trampoline file descriptor API madvenka
2020-09-22 21:53 ` [PATCH v2 2/4] [RFC] x86/trampfd: Provide support for the trampoline file descriptor madvenka
2020-09-22 21:53 ` [PATCH v2 3/4] [RFC] arm64/trampfd: " madvenka
2020-09-22 21:53 ` [PATCH v2 4/4] [RFC] arm/trampfd: " madvenka
2020-09-22 21:54 ` [PATCH v2 0/4] [RFC] Implement Trampoline File Descriptor Madhavan T. Venkataraman
2020-09-23 8:14 ` Pavel Machek
2020-09-23 9:14 ` Solar Designer
2020-09-23 14:11 ` Solar Designer
2020-09-23 15:18 ` Pavel Machek
2020-09-23 18:00 ` Solar Designer
2020-09-23 18:21 ` Solar Designer
2020-09-23 14:39 ` Florian Weimer
2020-09-23 18:09 ` Andy Lutomirski
2020-09-23 18:11 ` Solar Designer
2020-09-23 18:49 ` Arvind Sankar
2020-09-23 23:53 ` Madhavan T. Venkataraman
2020-09-23 19:41 ` Madhavan T. Venkataraman
2020-09-23 18:10 ` James Morris
2020-09-23 18:32 ` Madhavan T. Venkataraman
2020-09-23 8:42 ` Pavel Machek
2020-09-23 18:56 ` Madhavan T. Venkataraman
2020-09-23 20:51 ` Pavel Machek
2020-09-23 23:04 ` Madhavan T. Venkataraman
2020-09-24 16:44 ` Mickaël Salaün
2020-09-24 22:05 ` Pavel Machek
2020-09-25 10:12 ` Mickaël Salaün [this message]
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