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Clarify relationship btw MeshNetworks and ENABLE_HCM_INTERNAL_NET #3433

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Merged
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Feb 19, 2025
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Clarify relationship btw MeshNetworks and ENABLE_HCM_INTERNAL_NET #3433

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b05ce61
Clarify relationship btw MeshNetworks and ENABLE_HCM_INTERNAL_NET
jaellio Feb 6, 2025
40efdd8
Add release note
jaellio Feb 6, 2025
bf31f58
Clarify security implications of enabling HCM internal networks
jaellio Feb 6, 2025
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14 changes: 14 additions & 0 deletions mesh/v1alpha1/istio.mesh.v1alpha1.pb.html
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15 changes: 15 additions & 0 deletions mesh/v1alpha1/network.pb.go
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15 changes: 15 additions & 0 deletions mesh/v1alpha1/network.proto
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Expand Up @@ -114,6 +114,21 @@ message Network {
// locality: us-east-1a
// ```
//
// If `ENABLE_HCM_INTERNAL_NETWORKS` is set to true, MeshNetworks can be used to
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Do you think we need an example of how to do this?

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If Networks defaults to all mesh IPs then maybe not, but I need to clarify the default value of Networks

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From my quick investigation, I don't think there is a default Network configured. I had previously thought it defaulted to all mesh IPs. @ramaraochavali Since you are more familiar with this configuration could confirm this and review an additional example?

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I the documentation is correct. But I would hesitate to add the temporary feature flag reference here.

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Can we update this documentation when the feature flag is removed?

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But nothing is changed in network API. So not sure why we have to update here. Why is n't the main istio release notes not sufficient?

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@jaellio jaellio Feb 13, 2025 •
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I liked having the information here so it would be clearly displayed in our api docs on istio.io. Otherwise, the only documentation on how to utilize MeshNetworks to preserve envoy internal headers. I could modify/simplify the description and link to the upgrade note?

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I think specifying MeshNetworks can also be used to define "internal" addresses of mesh and provide an example is fine.

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I agree with @jaellio that the feature flag + example is useful//necessary here. Users who run into the Envoy behavior change are going to come to Istio documentation to tell them what to do. We should have a clear answer for them

// to explicitly define the networks in Envoy's internal address configuration.
// Envoy uses the IPs in the `internalAddressConfig` to decide whether or not to sanitize
// Envoy headers. If the IP address is listed an internal, the Envoy headers are not
// sanitized. As of Envoy 1.33, the default value for `internalAddressConfig` is set to
// an empty set. Previously, the default value was the set of all private IPs. Setting
// the `internalAddressConfig` to all private IPs (via Envoy's previous default behavior
// or via the MeshNetworks) will leave users with an Istio Ingress Gateway potentially
// vulnerable to `x-envoy` header manipulation by external sources. More information about
// this vulnerability can be found here:
// https://github.com/envoyproxy/envoy/security/advisories/GHSA-ffhv-fvxq-r6mf
// To preserve headers, you must explicitly configure MeshNetworks and set
// `ENABLE_HCM_INTERNAL_NETWORKS` to true. Envoy's `internalAddressConfig` will be set to
// the endpointed specified by `fromCidr`.
//
message MeshNetworks {
// The set of networks inside this mesh. Each network should
// have a unique name and information about how to infer the endpoints in
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16 changes: 16 additions & 0 deletions releasenotes/notes/mesh-network-internal-addr-config.yaml
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@@ -0,0 +1,16 @@
apiVersion: release-notes/v2
kind: bug-fix
area: documentation
issue:
- https://github.com/istio/istio/issues/53402

releaseNotes:
- |
**Fixed** documentation for using MeshNetworks to configure envoy internal address configuration
when ENABLE_HCM_INTERNAL_NETWORKS is set to true. As of Envoy 1.33, the default value for
internalAddressConfig is set to an empty set. Previously, the default value was the set of all
private IPs. To preserve Envoy headers, you must explicitly configure MeshNetworks
or revert to Envoy's prior behavior by setting envoy.reloadable_features.explicit_internal_address_config
to false. Setting MeshNetworks to all private IPs or reverting to Envoy's previous behavior will leave
users with an Istio Ingress Gateway potentially vulnerable to x-envoy header manipulation by external
sources. More information about this vulnerability can be found here: https://github.com/envoyproxy/envoy/security/advisories/GHSA-ffhv-fvxq-r6mf