netdev - Re: Network hang after c3f1010b30f7fc611139cfb702a8685741aa6827 with CIPSO & Smack

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Message-ID: <9998a0da-b273-43d4-84ad-a0539e6a69ac@cumulusnetworks.com>
Date:	Wed, 6 Jul 2016 09:28:57 -0700
From:	David Ahern <dsa@...ulusnetworks.com>
To:	Casey Schaufler <casey@...aufler-ca.com>,
	David Miller <davem@...emloft.net>,
	Paul Moore <paul@...l-moore.com>
Cc:	Linux-Netdev <netdev@...r.kernel.org>
Subject: Re: Network hang after c3f1010b30f7fc611139cfb702a8685741aa6827 with
 CIPSO & Smack

On 7/5/16 6:31 PM, Casey Schaufler wrote:
> On 7/5/2016 5:49 PM, David Ahern wrote:
>> On 7/5/16 5:38 PM, Casey Schaufler wrote:
>>> I have encountered a system hang with my Smack
>>> networking tests that bisects to the change below.
>>> I can't say that I have any idea why the change
>>> would impact the Smack processing, but there appears
>>> to be some serious packet processing going on. The
>>> Smack code is using CIPSO on the loopback interface.
>>> The test is supposed to verify that labels can be
>>> set on the packets using CIPSO. Unlabeled packets
>>> do not appear to be impacted. I do not know if SELinux
>>> is affected, and if not, why not. Smack and SELinux
>>> use CIPSO differently.
>>
>> What are the commands to repeat the test?
>>
> There is a tar file attached with the tests.
> Put the etc/smack/user file into /etc/smack/user.
> In the tools-2012 directory run make to build
> the tools. The test in question is called
> testnetworking.sh and needs to be run as root.
> You will need to configure Smack in the kernel,
> of course.
>

I understand Paul's point and glad to see the changes are not causing 
issues with his SELinux testing.

I have tried to reproduce the lockup you are seeing but not successful. 
I am using a jessie based VM with latest net-next kernel.

root@...ny-jessie3:~/smack/tools-2012# zcat /proc/config.gz | grep SMACK
CONFIG_SECURITY_SMACK=y
CONFIG_SECURITY_SMACK_BRINGUP=y
CONFIG_SECURITY_SMACK_NETFILTER=y
# CONFIG_DEFAULT_SECURITY_SMACK is not set

root@...ny-jessie3:~/smack/tools-2012# bash -x ./testnetworking.sh
<no lockup>

Send me your kernel config. Perhaps I do not have some config enabled.