memcached socket not released upon lbaas API request

Hi,

Thanks for reporting this bug. I was just checking Neutron code and I'm a bit confused as we are not using memcached in Neutron code anywhere.
Is this memcahed used by keystonemiddleware? And if it is, isn't that keystonemiddleware bug instead of neutron?

Hello,
I guess you are right. The memcached configuration is related to the authentication and thus to Keystone.
I didn't know that the socket management was handled by the keystone middleware. Maybe this interaction with the middleware can explain somehow the fact that the socket is somehow left open.

I do not how I should proceed. Should I copy the content of this ticket and create a new one on the keystone component, or there is a way to move it ?

Thanks a lot for your quick feedback
Sergio

Thanks for the clarification, I'll reset the affected project to keystonemiddleware now.

Since this report concerns a possible security risk, an incomplete
security advisory task has been added while the core security
reviewers for the affected project or projects confirm the bug and
discuss the scope of any vulnerability along with potential
solutions.

Just so I understand, a user can call the /v2.0/lbaas/loadbalancers method repeatedly and each invocation creates a new socket which does not terminate, allowing them to (quickly?) exhaust system resources when the process reaches the system file descriptor limit or no ephemeral ports are available to source new connections to memcached. Is this an accurate summary?

Neutron has caching from a quick look:

https://github.com/openstack/neutron/blob/master/neutron/common/cache_utils.py

I am confused on why this is keystonemiddleware, afaik the only thing ksm caches is the token, and we would be seeing this issue everywhere if it was leaving sockets open.

Hello,
I will try to clarify as much as possible this issue. To answer Jeremy's question in #5, the summary is right but I need to add that this feature (lbaas) is not enabled in the cluster. That's why there is a 404 message.

I answer to Gage comment in #6, we are also confused. Our team has check quite a while on internet because we were pretty sure the issue, if not related to an exotic setup, should be known by now. The complementary information I can provide is :
* We have two clusters running train version and the issue is present in both of them
* We have several clusters in Ocata version with the same monitoring setup and we haven't experienced the issue so far.

I don't know how much the keystone setup itself may impact this behavior, and I would like to avoid messing up things. However I will point out that we have added in Train deployment an identity federation setup in keystone with OIDC and Keycloak as authentication backend for cluster users. From my point of view this shouldn't impact Neutron's authentication, but this is the only tunning we made with respect to default authentication setup and is the main change with regard to the Ocata's deployment which use LDAP as authentication backend for cluster users.

Please, let me know if we can provide you any traces or cluster configuration information that could help understand what is going on.

Best regards
Sergio

Could this be a duplicate of (or at least related to) bug 1883659 do you think?

They do seem very similar, and there is a bit more discussion and work being done on the public one as well.

Has there been any observation here with the other neutron APIs not releasing memcache sockets, or has it been confined to only lbaas API requests in this case?

This does closely resemble bug 1883659 from the descriptions.

Hello,
I pretty much agree with you. The behavior described in bug 1883659 is quite similar to what we observe on our clusters. It would be interesting to check if they have also requests that hits unused parts of the neutron-server API frequently.

I've subscribed the oslo-coresec reviewers and added a new bugtask for oslo.cache, hopefully we can get some additional clarity that way. Ultimately, I'm not convinced keeping this bug private is helping anyone, and strongly suggest we switch it to Public Security so we can at least add the potential vulnerability concerns to the increasing amount of community discussion around bug 1883659.

This may be a duplicate to https://bugs.launchpad.net/keystonemiddleware/+bug/1883659

I second that.

We were working on a possible fix for this in this patch[1], but there are still some missing changes to be made.

And Sergio, you have a cleartext memcache_secret_key in your Neutron config file.

[1] https://review.opendev.org/#/c/742193/

It looks to me like change https://review.opendev.org/742193 and subsequent review discussion spells out the security risks fairly clearly, so this is basically a publicly known issue at this point. Since I have seen no objections to my proposal in comment #12 two weeks ago, I'm switching this report to Public Security so that it can weigh more clearly in any discussion of proposed fixes or mitigations.

I fully agree with the analysis. The patch seems address the issue we faced.

We will check whether the patch is back ported to Train release. In that case we will test it.

Thanks a lot to all of you to help out figure out the root cause.

PS: Regarding comment on #14, I couldn't manage to update the paste-bin contents but It is not big deal.

It looks like this may be the same as bug 1883659 and bug 1888394.

At this point there's no clear exploit scenario and the description of this and the other two presumed related reports seems to be of a normal (albeit potentially crippling) bug. As such, the vulnerability management team is going to treat this as a class D report per our taxonomy and not issue an advisory once it's fixed, but if anyone disagrees we can reconsider the position: https://security.openstack.org/vmt-process.html#incident-report-taxonomy

The linked patch has merged, so I'm going to mark this as fixed. Feel free to reopen if the problem doesn't go away with the new oslo.cache release.

This issue was fixed in the openstack/keystonemiddleware 9.3.0 release.

Fix proposed to branch: stable/wallaby
Review: https://review.opendev.org/c/openstack/keystonemiddleware/+/793917