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punktfunk/.cargo/audit.toml
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enricobuehler 60de506f66 fix(host/gamestream): correct the rsa-Marvin (S7) rationale + cap pairing signatures
Red-team found the .cargo/audit.toml justification for RUSTSEC-2023-0071 was
materially wrong: it claimed "Marvin targets decryption, so the vulnerable path
isn't exercised" — but the advisory is a variable-time modexp of the secret
exponent, which RSA *signing* (signing_key.sign) also runs. The accept is still
correct, for the RIGHT reasons (no decryption/padding oracle; the signed
serversecret is host-random not attacker-chosen; signing is operator-PIN-gated;
GameStream is off by default and the native QUIC plane uses rustls, not rsa;
Moonlight mandates RSA-2048 so the GameStream key can't move off it). Rewrite
the rationale accordingly.

Also shut the timing-sample amplifier the review surfaced: the pairing session
was never marked after phase 3, so a peer past phase 1 could loop phase2/phase3
to harvest many RSA signing-time samples. Sign exactly once per ceremony
(reject a repeated serverchallengeresp).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-29 19:17:37 +00:00

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2.9 KiB
TOML

# cargo-audit configuration — consumed by `.gitea/workflows/audit.yml` (`cargo audit`).
#
# Silence only advisories that are KNOWN-UNFIXABLE and either not applicable to how we use the crate
# or an accepted, documented risk. Keep this list TIGHT and justify every entry — an ignore here
# means the audit job stops flagging it, so the reasoning must hold up.
#
# NOTE: `cargo audit` (no `--deny warnings`) fails only on *vulnerabilities*, not on the
# `unmaintained` warnings (audiopus_sys via opus, paste via utoipa-axum). Both are transitive, at
# their latest published version with no successor, so there's nothing to bump — left visible on
# purpose so we keep getting the maintenance signal; they do not fail CI. (rustls-pemfile was dropped
# 2026-06-29 by removing axum-server's unused tls-rustls feature + moving our own PEM parsing to
# rustls-pki-types; memmap2's unsoundness was fixed by the 0.9.11 bump.)
[advisories]
ignore = [
# rsa "Marvin Attack" (RUSTSEC-2023-0071): a timing side-channel in the rsa crate's variable-time
# modular exponentiation of the SECRET exponent. IMPORTANT — this affects the RSA private-key op in
# general, INCLUDING signing (m^d mod n), which the host DOES perform (gamestream/pairing.rs
# `signing_key.sign(&serversecret)`). It is NOT, as an earlier version of this note wrongly claimed,
# limited to decryption — so "the vulnerable path isn't exercised" is false; signing exercises it.
# We accept it because the attack is not practically reachable here, NOT because the path is unused:
# * No RSA decryption / PKCS#1v1.5 padding oracle exists anywhere (every `decrypt` in the tree is
# AES/AES-GCM), so the classic Bleichenbacher/Marvin chosen-ciphertext oracle is absent.
# * The only signed message (`serversecret`) is HOST-generated random, never attacker-chosen — so
# there's no adaptive chosen-input probing (the lever remote RSA-timing key recovery needs); and
# signing is gated behind the operator-entered pairing PIN, ONE signature per ceremony (a
# repeated phase-3 is rejected — gamestream/pairing.rs — to deny a passive timing-sample harvester).
# * GameStream is OFF by default (bare `serve` is native-only); the secure native QUIC plane uses
# rustls' constant-time backend, NOT the rsa crate. RSA is touched only on the opt-in,
# trusted-LAN GameStream/Moonlight pairing handshake. Moonlight mandates RSA-2048, so the
# GameStream identity cannot move to Ed25519/ECDSA (only the native identity could, and it
# already avoids the rsa crate).
# There is NO fixed rsa release (the constant-time rewrite is still unreleased upstream). Revisit if:
# a constant-time rsa ships (then drop this), the host ever signs an attacker-chosen message with
# this key, or any RSA decryption / key-transport using the private key is added.
"RUSTSEC-2023-0071",
]