Comment 38 for bug 1545092

Thanks Brian, let me know if this is ok:

Glance Image service v1 and v2 api image-create vulnerability
---

### Summary ###
No limits are enforced within the Glance image service for both v1 and
v2 `/images` API POST method for authenticated users, resulting in possible
denial of service attacks through database table saturation.

### Affected Services / Software ###
All versions of Glance image service.

### Discussion ###
Within the Glance image service, calls to the POST method within v1 or
v2/images creates an image (record) in `queued` status. There is no limit
enforced within the Glance API on the number of images a single tenant may
create, just on the total amount of storage a single user may consume.

Therefore a user could either maliciously or unintentionally fill multiple
database tables (images, image_properties, image_tags, image_members) with
useless image records, thereby causing a denial of service by lengthening
transaction response times in the Glance database.

### Recommended Actions ###
For all versions of Glance that expose either the v1 and v2/images API,
operators are recommended to deploy external rate-limiting proxies or web
application firewalls, to provide a front layer of protection to glance.

The following solutions may be considered, however it is key that the operator
carefully plans and considers the individual performance needs of users and
services within their OpenStack cloud, when configuring any rate limiting
functionality.

#### Repose ####
Repose provides a rate limiting filter, that can utilise limits by IP,
Role (OpenStack Identity v3 filter) or header.

https://repose.atlassian.net/wiki/display/REPOSE/Rate+Limiting+Filter

#### NGINX ####
NGINX provides the limit_req_module, which can be used to provide a global rate
limit. By means of a `map`, it can be limited to just the POST method.

Further details can be found on the nginx site:
http://nginx.org/en/docs/http/ngx_http_limit_req_module.html

#### HAProxy ####
HAProxy can provide inherent rate-limiting using stick-tables with a General
Purpose Counter (gpc)

Further details can be found on the haproxy website:
http://blog.haproxy.com/2012/02/27/use-a-load-balancer-as-a-first-row-of-defense-against-ddos)

#### Apache ####
A number of solutions can be explored here as follows.

##### mod_ratelimit #####
http://httpd.apache.org/docs/2.4/mod/mod_ratelimit.html

##### mod_qos #####
http://opensource.adnovum.ch/mod_qos/dos.html

##### mod_evasive #####
https://www.digitalocean.com/community/tutorials/how-to-protect-against-dos-and-ddos-with-mod_evasive-for-apache-on-centos-7)

##### mod_security #####
https://www.modsecurity.org/

#### Limit `add_image` to admin role ####

Another possible mitigation is to restrict image creation to the admin role,
however this should only be done for those cases in which there are Glance nodes
dedicated to end-user access only. Restriction to admin only on Glance nodes
that serve OpenStack services will remove the ability to create snapshots from
the Compute API.

To restrict image creation to the role admin only, amend
`/etc/glance/policy.json` accordingly.

    "add_image": "role:admin",

### Contacts / References ###
Author: Luke Hinds, Red Hat
This OSSN : https://wiki.openstack.org/wiki/OSSN/OSSN-0076
Original LaunchPad Bug : https://bugs.launchpad.net/ossn/+bug/1545092
OpenStack Security ML : <email address hidden>
OpenStack Security Group : https://launchpad.net/~openstack-ossg