linux-kernel - Re: [PATCH RESEND/V2] crypto: Ignore validity dates of X.509 certificates at loading/parsing time

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 06 Jun 2013 13:17:23 +0200
From:	Alexander Holler <holler@...oftware.de>
To:	Alexander Holler <holler@...oftware.de>
CC:	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Rusty Russell <rusty@...tcorp.com.au>,
	David Howells <dhowells@...hat.com>,
	Josh Boyer <jwboyer@...hat.com>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH  RESEND/V2] crypto: Ignore validity dates of X.509 certificates
 at loading/parsing time

Am 02.05.2013 16:09, schrieb Alexander Holler:
> I don't see any real use case where checking the validity dates of X.509
> certificates at parsing time adds any security gain. In contrast, doing so
> makes MODSIGN unusable on systems without a RTC (or systems with a possible
> wrong date in a existing RTC, or systems where the RTC is read after the keys
> got loaded).
> 
> If something really cares about the dates, it should check them at the time
> when the certificates are used, not when they are loaded and parsed.
> 
> So just remove the validity check of the dates in the parser.
> 
> Signed-off-by: Alexander Holler <holler@...oftware.de>
> Cc: stable@...r.kernel.org

As it just happened to me again and I've recently posted some patches
which do make it possible to experience the problem on x86 systems too,
here is a reminder.

To replay the problem (on x86 or any other arch), apply the 3 patches in
this series:

https://lkml.org/lkml/2013/6/5/430

build a kernel with CONFIG_MODULE_SIG_FORCE=y and start that kernel with
hctosys=none as kernel command line parameter.

This will disable the "persistent" clock (and any RTC), thus the kernel
will refuse to load modules because it doesn't has a valid time when
loading the certificate.

Regards,

Alexander Holler
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/