Merge branch 'security-enable-image-proxy' into 'master'

Use image proxy to mitigate stealing ip addresses

Closes #2812

See merge request gitlab/gitlabhq!2926

3 files changed, 39 insertions, 0 deletions

diff --git a/doc/api/settings.md b/doc/api/settings.md
index 710b63c9a2f..e3d8fe68e08 100644
--- a/doc/api/settings.md
+++ b/doc/api/settings.md
@@ -68,6 +68,9 @@ Example response:
    "allow_local_requests_from_hooks_and_services": true,
    "allow_local_requests_from_web_hooks_and_services": true,
    "allow_local_requests_from_system_hooks": false
+   "asset_proxy_enabled": true,
+   "asset_proxy_url": "https://assets.example.com",
+   "asset_proxy_whitelist": ["example.com", "*.example.com", "your-instance.com"]
 }
 ```
 
@@ -141,6 +144,9 @@ Example response:
   "user_show_add_ssh_key_message": true,
   "file_template_project_id": 1,
   "local_markdown_version": 0,
+  "asset_proxy_enabled": true,
+  "asset_proxy_url": "https://assets.example.com",
+  "asset_proxy_whitelist": ["example.com", "*.example.com", "your-instance.com"],
   "geo_node_allowed_ips": "0.0.0.0/0, ::/0",
   "allow_local_requests_from_hooks_and_services": true,
   "allow_local_requests_from_web_hooks_and_services": true,
@@ -186,6 +192,10 @@ are listed in the descriptions of the relevant settings.
 | `allow_local_requests_from_hooks_and_services` | boolean    | no                                   | (Deprecated: Use `allow_local_requests_from_web_hooks_and_services` instead) Allow requests to the local network from hooks and services. |
 | `allow_local_requests_from_web_hooks_and_services` | boolean    | no                                   | Allow requests to the local network from web hooks and services. |
 | `allow_local_requests_from_system_hooks` | boolean    | no                                   | Allow requests to the local network from system hooks. |
+| `asset_proxy_enabled`                    | boolean          | no                                   | (**If enabled, requires:** `asset_proxy_url`) Enable proxying of assets. GitLab restart is required to apply changes. |
+| `asset_proxy_secret_key`                 | string           | no                                   | Shared secret with the asset proxy server. GitLab restart is required to apply changes. |
+| `asset_proxy_url`                        | string           | no                                   | URL of the asset proxy server. GitLab restart is required to apply changes. |
+| `asset_proxy_whitelist`                  | string or array of strings | no                         | Assets that match these domain(s) will NOT be proxied. Wildcards allowed. Your GitLab installation URL is automatically whitelisted. GitLab restart is required to apply changes. |
 | `authorized_keys_enabled`                | boolean          | no                                   | By default, we write to the `authorized_keys` file to support Git over SSH without additional configuration. GitLab can be optimized to authenticate SSH keys via the database file. Only disable this if you have configured your OpenSSH server to use the AuthorizedKeysCommand. |
 | `auto_devops_domain`                     | string           | no                                   | Specify a domain to use by default for every project's Auto Review Apps and Auto Deploy stages. |
 | `auto_devops_enabled`                    | boolean          | no                                   | Enable Auto DevOps for projects by default. It will automatically build, test, and deploy applications based on a predefined CI/CD configuration. |
diff --git a/doc/security/README.md b/doc/security/README.md
index 5d498ac7602..fa34f07060e 100644
--- a/doc/security/README.md
+++ b/doc/security/README.md
@@ -17,3 +17,4 @@ type: index
 - [Enforce Two-factor authentication](two_factor_authentication.md)
 - [Send email confirmation on sign-up](user_email_confirmation.md)
 - [Security of running jobs](https://docs.gitlab.com/runner/security/)
+- [Proxying images](asset_proxy.md)
diff --git a/doc/security/asset_proxy.md b/doc/security/asset_proxy.md
new file mode 100644
index 00000000000..f25910d3db7
--- /dev/null
+++ b/doc/security/asset_proxy.md
@@ -0,0 +1,28 @@
+A possible security concern when managing a public facing GitLab instance is
+the ability to steal a users IP address by referencing images in issues, comments, etc.
+
+For example, adding `![Example image](http://example.com/example.png)` to
+an issue description will cause the image to be loaded from the external
+server in order to be displayed.  However this also allows the external server
+to log the IP address of the user.
+
+One way to mitigate this is by proxying any external images to a server you
+control.  GitLab handles this by allowing you to run the "Camo" server
+[cactus/go-camo](https://github.com/cactus/go-camo#how-it-works).
+The image request is sent to the Camo server, which then makes the request for
+the original image.  This way an attacker only ever seems the IP address
+of your Camo server.
+
+Once you have your Camo server up and running, you can configure GitLab to
+proxy image requests to it.  The following settings are supported:
+
+| Attribute                | Description |
+| ------------------------ | ----------- |
+| `asset_proxy_enabled`    | (**If enabled, requires:** `asset_proxy_url`) Enable proxying of assets. |
+| `asset_proxy_secret_key` | Shared secret with the asset proxy server. |
+| `asset_proxy_url`        | URL of the asset proxy server. |
+| `asset_proxy_whitelist`  | Assets that match these domain(s) will NOT be proxied. Wildcards allowed. Your GitLab installation URL is automatically whitelisted. |
+
+These can be set via the [Application setting API](../api/settings.md)
+
+Note that a GitLab restart is required to apply any changes.