fix(server): real signature verification in pre-receive hook (audit S1)
verify_commit previously loaded devices.json/revoked.json and threw both away, accepting any commit whose stderr contained "GOODSIG" or "Good signature". This left device registration and revocation as no-ops: unregistered keys could push, revoked keys kept working. The fix: - Build a temp gpg.ssh.allowedSignersFile from devices.json at the commit, passed via GIT_CONFIG_COUNT/KEY/VALUE env (no global git config mutation). - Run git verify-commit --raw and parse SHA256 fingerprint from stderr regardless of exit code (SSH git outputs the "Good" line even for keys not in allowed-signers, with "No principal matched" + exit 1). - Check revoked.json FIRST: reject if committer_ts >= revoked_at; accept historical commits (committer_ts < revoked_at). - Reject if fingerprint is not in active devices.json. - Bootstrap: accept only when BOTH devices.json AND revoked.json are empty/absent (not just devices.json alone). Acceptance: 4 integration tests covering the matrix. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
adlee-was-taken
@@ -9,6 +9,8 @@ anyhow = "1"
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clap = { version = "4", features = ["derive"] }
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serde = { version = "1", features = ["derive"] }
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serde_json = "1"
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tempfile = "3"
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regex = "1"
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[dev-dependencies]
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assert_cmd = "2"
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@@ -1,5 +1,6 @@
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//! relicario-server -- pre-receive hook for signature verification.
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use std::fs;
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use std::process::Command;
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use anyhow::{Context, Result};
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@@ -34,49 +35,120 @@ fn main() -> Result<()> {
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}
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fn verify_commit(commit: &str) -> Result<()> {
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// Get devices.json at this commit
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let devices_json = match git_show(commit, ".relicario/devices.json") {
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Ok(json) => json,
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Err(_) => {
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// No devices.json yet -- bootstrap mode, allow unsigned
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eprintln!("OK: commit {} (bootstrap - no devices.json)", commit);
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eprintln!("OK: commit {commit} (bootstrap - no devices.json)");
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return Ok(());
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}
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};
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let devices: Vec<DeviceEntry> = serde_json::from_str(&devices_json)
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.context("parse devices.json")?;
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// Bootstrap: if devices.json is empty, allow unsigned
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if devices.is_empty() {
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eprintln!("OK: commit {} (bootstrap - empty devices.json)", commit);
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return Ok(());
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}
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// Get revoked.json (may not exist)
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let revoked: Vec<RevokedEntry> = git_show(commit, ".relicario/revoked.json")
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.ok()
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.and_then(|s| serde_json::from_str(&s).ok())
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.unwrap_or_default();
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// Get commit signature
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// True bootstrap: no devices ever registered and none revoked.
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if devices.is_empty() && revoked.is_empty() {
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eprintln!("OK: commit {commit} (bootstrap - no devices registered)");
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return Ok(());
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}
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// Build temp allowed-signers file from registered devices.
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let tmp = tempfile::tempdir().context("create tempdir")?;
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let allowed_path = tmp.path().join("allowed_signers");
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let mut allowed_body = String::new();
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for d in &devices {
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allowed_body.push_str("relicario ");
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allowed_body.push_str(d.public_key.trim());
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allowed_body.push('\n');
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}
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fs::write(&allowed_path, &allowed_body).context("write allowed_signers")?;
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// Run git verify-commit --raw. Capture both exit code and stderr.
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// NOTE: we do NOT short-circuit on non-zero exit here because even for
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// unregistered keys git still outputs "Good ... key SHA256:..." on stderr.
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let output = Command::new("git")
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.args(["verify-commit", "--raw", commit])
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.env("GIT_CONFIG_COUNT", "1")
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.env("GIT_CONFIG_KEY_0", "gpg.ssh.allowedSignersFile")
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.env("GIT_CONFIG_VALUE_0", allowed_path.as_os_str())
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.output()
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.context("git verify-commit")?;
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// Check if signed
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let stderr = String::from_utf8_lossy(&output.stderr);
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if !stderr.contains("GOODSIG") && !stderr.contains("Good signature") {
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eprintln!("REJECT: commit {} is not signed by a registered device", commit);
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// Parse the SHA-256 fingerprint from stderr.
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// SSH signature output: "Good "git" signature ... with ED25519 key SHA256:<base64>"
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let re = regex::Regex::new(r"key (SHA256:[A-Za-z0-9+/]+)").expect("static regex");
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let signing_fp = match re.captures(&stderr).and_then(|c| c.get(1)) {
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Some(m) => m.as_str().to_string(),
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None => {
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// No fingerprint in stderr = unsigned or completely malformed signature.
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eprintln!(
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"REJECT: commit {commit} — no valid signature found (stderr: {})",
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stderr.trim()
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);
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std::process::exit(1);
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}
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};
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// Build fingerprint → entry maps.
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let mut device_by_fp: std::collections::HashMap<String, &DeviceEntry> =
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std::collections::HashMap::new();
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for d in &devices {
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if let Ok(fp) = relicario_core::device::fingerprint(&d.public_key) {
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device_by_fp.insert(fp, d);
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}
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}
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let mut revoked_by_fp: std::collections::HashMap<String, &RevokedEntry> =
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std::collections::HashMap::new();
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for r in &revoked {
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if let Ok(fp) = relicario_core::device::fingerprint(&r.public_key) {
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revoked_by_fp.insert(fp, r);
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}
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}
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// Get committer date (NOT author date).
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let ct_out = Command::new("git")
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.args(["show", "-s", "--format=%ct", commit])
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.output()
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.context("git show committer date")?;
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let committer_ts: i64 = String::from_utf8_lossy(&ct_out.stdout)
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.trim()
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.parse()
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.context("parse committer timestamp")?;
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// Check revocation FIRST (revoked entries may not be in devices anymore).
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if let Some(r) = revoked_by_fp.get(&signing_fp) {
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if committer_ts >= r.revoked_at {
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eprintln!(
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"REJECT: commit {commit} — signed by revoked device '{}' \
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(committer ts {committer_ts} >= revoked_at {})",
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r.name, r.revoked_at
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);
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std::process::exit(1);
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}
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// Historical commit: committer_ts < revoked_at → was valid when signed.
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eprintln!(
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"OK: commit {commit} — historical commit signed by '{}' before revocation",
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r.name
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);
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return Ok(());
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}
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// Not revoked — must be in active devices.
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if !device_by_fp.contains_key(&signing_fp) {
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eprintln!(
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"REJECT: commit {commit} — signed by unregistered device (fingerprint {signing_fp})"
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);
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std::process::exit(1);
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}
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// Ensure the signing key is not revoked.
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// The allowed-signers file approach means git verify-commit already checks
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// against the list; we additionally guard against revoked.json entries.
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let _ = &revoked; // revoked list is loaded; enforcement via git allowed-signers
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eprintln!("OK: commit {} verified", commit);
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eprintln!("OK: commit {commit} verified (signed by '{}')", device_by_fp[&signing_fp].name);
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Ok(())
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}
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230
crates/relicario-server/tests/verify_commit.rs
Normal file
230
crates/relicario-server/tests/verify_commit.rs
Normal file
@@ -0,0 +1,230 @@
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//! Acceptance tests for `relicario-server verify-commit`.
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//!
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//! Four scenarios from audit S1:
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//! 1. Registered non-revoked key → exit 0
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//! 2. Unregistered key → exit 1 (stderr contains "unregistered")
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//! 3. Revoked key, commit AFTER revoked_at → exit 1 (stderr contains "revoked")
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//! 4. Revoked key, commit BEFORE revoked_at (historical) → exit 0
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use std::fs;
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use std::path::{Path, PathBuf};
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use std::process::Command;
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use assert_cmd::Command as AssertCommand;
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use predicates::prelude::*;
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use relicario_core::device::{generate_keypair, DeviceEntry, RevokedEntry};
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use tempfile::TempDir;
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fn write_keypair(dir: &Path, name: &str) -> (PathBuf, PathBuf, String) {
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let (priv_pem, pub_line) = generate_keypair().expect("generate keypair");
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let priv_path = dir.join(format!("{name}.key"));
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let pub_path = dir.join(format!("{name}.pub"));
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fs::write(&priv_path, priv_pem.as_str()).unwrap();
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fs::write(&pub_path, &pub_line).unwrap();
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#[cfg(unix)]
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{
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use std::os::unix::fs::PermissionsExt;
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fs::set_permissions(&priv_path, fs::Permissions::from_mode(0o600)).unwrap();
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}
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(priv_path, pub_path, pub_line)
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}
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fn git(repo: &Path, args: &[&str], extra_env: &[(&str, &str)]) {
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let mut cmd = Command::new("git");
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cmd.current_dir(repo).args(args);
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for (k, v) in extra_env {
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cmd.env(k, v);
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}
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let status = cmd.status().expect("spawn git");
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assert!(status.success(), "git {args:?} failed");
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}
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fn init_repo(repo: &Path) {
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git(repo, &["init", "-q", "-b", "main"], &[]);
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git(repo, &["config", "user.email", "test@test"], &[]);
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git(repo, &["config", "user.name", "test"], &[]);
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git(repo, &["commit", "--allow-empty", "-q", "-m", "init"], &[]);
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}
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fn sign_commit(
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repo: &Path,
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signing_key: &Path,
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allowed_signers: &Path,
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committer_unix: i64,
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msg: &str,
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file_path: &str,
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file_content: &str,
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) -> String {
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fs::write(repo.join(file_path), file_content).unwrap();
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git(repo, &["add", file_path], &[]);
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let date = format!("@{committer_unix} +0000");
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git(
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repo,
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&[
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"-c", "gpg.format=ssh",
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"-c", &format!("user.signingkey={}", signing_key.display()),
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"-c", &format!("gpg.ssh.allowedSignersFile={}", allowed_signers.display()),
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"commit", "-S", "-q", "-m", msg,
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],
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&[
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("GIT_AUTHOR_DATE", &date),
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("GIT_COMMITTER_DATE", &date),
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],
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);
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let out = Command::new("git")
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.current_dir(repo)
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.args(["rev-parse", "HEAD"])
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.output()
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.unwrap();
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String::from_utf8(out.stdout).unwrap().trim().to_string()
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}
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fn write_device_files(repo: &Path, devices: &[DeviceEntry], revoked: &[RevokedEntry]) {
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let dir = repo.join(".relicario");
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fs::create_dir_all(&dir).unwrap();
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fs::write(dir.join("devices.json"), serde_json::to_string_pretty(devices).unwrap()).unwrap();
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fs::write(dir.join("revoked.json"), serde_json::to_string_pretty(revoked).unwrap()).unwrap();
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git(repo, &["add", ".relicario"], &[]);
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git(repo, &["commit", "-q", "-m", "device files"], &[]);
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}
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#[test]
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fn registered_non_revoked_key_accepted() {
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let tmp = TempDir::new().unwrap();
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let repo = tmp.path();
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init_repo(repo);
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let (priv_a, _, pub_a) = write_keypair(repo, "alice");
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write_device_files(
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repo,
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&[DeviceEntry {
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name: "alice".into(),
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public_key: pub_a.clone(),
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added_at: 1_700_000_000,
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added_by: "bootstrap".into(),
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}],
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&[],
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);
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let allowed = repo.join("test_allowed_signers");
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fs::write(&allowed, format!("relicario {}\n", pub_a.trim())).unwrap();
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let sha = sign_commit(repo, &priv_a, &allowed, 1_710_000_000, "x", "a.txt", "hi");
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AssertCommand::cargo_bin("relicario-server")
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.unwrap()
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.current_dir(repo)
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.args(["verify-commit", &sha])
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.assert()
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.success();
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}
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#[test]
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fn unregistered_key_rejected() {
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let tmp = TempDir::new().unwrap();
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let repo = tmp.path();
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init_repo(repo);
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let (_, _, pub_a) = write_keypair(repo, "alice");
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let (priv_evil, _, pub_evil) = write_keypair(repo, "evil");
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// Only Alice is registered.
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write_device_files(
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repo,
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&[DeviceEntry {
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name: "alice".into(),
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public_key: pub_a.clone(),
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added_at: 1_700_000_000,
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added_by: "bootstrap".into(),
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}],
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&[],
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);
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// Evil signs against a file containing both keys so git commit signing works,
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// but the binary's allowed-signers (from devices.json) only has Alice.
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let allowed = repo.join("test_allowed_signers");
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fs::write(
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&allowed,
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format!("relicario {}\nrelicario {}\n", pub_a.trim(), pub_evil.trim()),
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)
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.unwrap();
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let sha = sign_commit(repo, &priv_evil, &allowed, 1_710_000_000, "evil", "a.txt", "hi");
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AssertCommand::cargo_bin("relicario-server")
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.unwrap()
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.current_dir(repo)
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.args(["verify-commit", &sha])
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.assert()
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.failure()
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.stderr(predicate::str::contains("unregistered"));
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}
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#[test]
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fn revoked_key_after_revoked_at_rejected() {
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let tmp = TempDir::new().unwrap();
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let repo = tmp.path();
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init_repo(repo);
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let (priv_a, _, pub_a) = write_keypair(repo, "alice");
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// Alice's entry is only in revoked.json (was removed from devices.json after revocation).
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write_device_files(
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repo,
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&[],
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&[RevokedEntry {
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name: "alice".into(),
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public_key: pub_a.clone(),
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revoked_at: 1_705_000_000,
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revoked_by: "admin".into(),
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}],
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);
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let allowed = repo.join("test_allowed_signers");
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fs::write(&allowed, format!("relicario {}\n", pub_a.trim())).unwrap();
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// Commit dated AFTER revocation.
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let sha = sign_commit(repo, &priv_a, &allowed, 1_710_000_000, "post", "a.txt", "hi");
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AssertCommand::cargo_bin("relicario-server")
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.unwrap()
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.current_dir(repo)
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.args(["verify-commit", &sha])
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.assert()
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.failure()
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.stderr(predicate::str::contains("revoked"));
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}
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#[test]
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fn revoked_key_before_revoked_at_accepted_historical() {
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let tmp = TempDir::new().unwrap();
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let repo = tmp.path();
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init_repo(repo);
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let (priv_a, _, pub_a) = write_keypair(repo, "alice");
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// Same as above: Alice only in revoked.json.
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write_device_files(
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repo,
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&[],
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&[RevokedEntry {
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name: "alice".into(),
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public_key: pub_a.clone(),
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revoked_at: 1_705_000_000,
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revoked_by: "admin".into(),
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}],
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);
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let allowed = repo.join("test_allowed_signers");
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fs::write(&allowed, format!("relicario {}\n", pub_a.trim())).unwrap();
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// Commit dated BEFORE revocation -- historical case must pass.
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let sha = sign_commit(repo, &priv_a, &allowed, 1_700_000_000, "historical", "a.txt", "hi");
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AssertCommand::cargo_bin("relicario-server")
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.unwrap()
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.current_dir(repo)
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.args(["verify-commit", &sha])
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.assert()
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.success();
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}
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Reference in New Issue
Block a user