envoyproxy/envoy

Crypto-grade hashing for resource sharing

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#11,967 opened on Jul 8, 2020

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area/securityarea/xdsbughelp wanted

Description

Currently, we use MesasgeUtil::hash in various places, e.g. SDS, to hash a config source (https://github.com/envoyproxy/envoy/blob/master/source/common/secret/secret_manager_impl.h#L82).

Since our threat model has the control plane as trusted, this isn't a huge issue. But if we make the control plane untrusted in the future, this can be somewhat scary. As an example, imagine an Envoy that has delegated listener config (with SDS) to TrustedControlPlane and another listener config (with SDS) to SuperScaryControlPlane. It's plausible that SuperScaryControlPlane is able to engineer a collision and steal secrets via the dynamic prover's dedupe algorithm, since we're only using the weak xxhash.

This is something we probably should fix before considering Envoy robust to untrusted control plane or ready for arbitrary federation.

CC @antoniovicente @kyessenov

Contributor guide

Tech stack
cpp
Domain
security
Issue type
security
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++Cryptographic hash functionsEnvoy internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Research the current usage of MessageUtil::hash in SDS and other places. Evaluate cryptographic hash functions such as SHA 256 or BLAKE2. Modify the hash function in source/common/secret/secret manager impl.h and other relevant files. Ensure no performance regression. Discuss with maintainers for preferred hash algorithm.