Gandalf the Greybeard (PE)
5f3f0ab94d
Contamination class: a stale GH_CONFIG_DIR inherited from a prior session or a different agent's workspace caused generate-token.sh to write .gh-token into a foreign workspace, silently granting that agent's gh config access to the wrong token. Three hardening changes: 1. agent-setup/scripts/setup.sh — before deriving GH_CONFIG_DIR from AGENT_HOME, warn and unset any inherited value that points outside AGENT_HOME. This prevents the contaminated value from leaking into the derived path or the dotfile. 2. agent-setup/SKILL.md — correct the sourcing example from `source ~/.env` to `source "$AGENT_HOME/.env"` so the dotfile is sourced from the documented location (setup.sh writes to $AGENT_HOME/.env, not ~/ which may differ). 3. github-app-token/scripts/generate-token.sh — (a) add a hard die() guard that refuses to write the token when GH_CONFIG_DIR is outside AGENT_HOME; (b) pin GH_CONFIG_DIR="$GH_TOKEN_DIR" on the gh auth login invocation so it cannot fall back to any inherited config dir. Verified: - bash -n passes on both modified scripts - With GH_CONFIG_DIR=/tmp/someone-elses/.github AGENT_HOME=/tmp/me, setup.sh warns + overrides; generate-token.sh dies before writing. - With GH_CONFIG_DIR unset and a valid AGENT_HOME, behaviour is unchanged (token lands in $AGENT_HOME/.github). Co-Authored-By: Paperclip <noreply@paperclip.ing>
79 lines
3.0 KiB
Bash
Executable File
79 lines
3.0 KiB
Bash
Executable File
#!/usr/bin/env bash
|
|
set -euo pipefail
|
|
|
|
die() { echo "ERROR: $*" >&2; exit 1; }
|
|
|
|
# --- Validate required env vars ---
|
|
[[ -z "${GITHUB_APP_ID:-}" ]] && die "GITHUB_APP_ID is not set"
|
|
[[ -z "${GITHUB_APP_INSTALLATION_ID:-}" ]] && die "GITHUB_APP_INSTALLATION_ID is not set"
|
|
|
|
# Resolve PEM key: prefer GITHUB_APP_PEM (inline data), fall back to GITHUB_APP_PEM_FILE
|
|
_CLEANUP_PEM_FILE=""
|
|
if [[ -n "${GITHUB_APP_PEM:-}" ]]; then
|
|
_TMP_PEM=$(mktemp)
|
|
_CLEANUP_PEM_FILE="$_TMP_PEM"
|
|
printf '%s' "$GITHUB_APP_PEM" > "$_TMP_PEM"
|
|
chmod 600 "$_TMP_PEM"
|
|
GITHUB_APP_PEM_FILE="$_TMP_PEM"
|
|
elif [[ -n "${GITHUB_APP_PEM_FILE:-}" ]]; then
|
|
[[ ! -f "$GITHUB_APP_PEM_FILE" ]] && die "PEM file not found: $GITHUB_APP_PEM_FILE"
|
|
else
|
|
die "Either GITHUB_APP_PEM (inline PEM data) or GITHUB_APP_PEM_FILE (path to PEM file) must be set"
|
|
fi
|
|
|
|
cleanup() { [[ -n "$_CLEANUP_PEM_FILE" ]] && rm -f "$_CLEANUP_PEM_FILE"; }
|
|
trap cleanup EXIT
|
|
|
|
for cmd in openssl curl jq gh; do
|
|
command -v "$cmd" >/dev/null 2>&1 || die "Required command not found: $cmd"
|
|
done
|
|
|
|
# --- Build JWT (valid 10 minutes) ---
|
|
b64url() { openssl enc -base64 -A | tr '+/' '-_' | tr -d '='; }
|
|
|
|
NOW=$(date +%s)
|
|
HEADER=$(printf '{"alg":"RS256","typ":"JWT"}' | b64url)
|
|
PAYLOAD=$(printf '{"iat":%s,"exp":%s,"iss":"%s"}' "$NOW" "$((NOW + 600))" "$GITHUB_APP_ID" | b64url)
|
|
SIGNED="${HEADER}.${PAYLOAD}"
|
|
SIG=$(printf '%s' "$SIGNED" | openssl dgst -binary -sha256 -sign "$GITHUB_APP_PEM_FILE" | b64url)
|
|
JWT="${SIGNED}.${SIG}"
|
|
|
|
# --- Exchange JWT for installation access token ---
|
|
RESPONSE=$(curl -sf -X POST \
|
|
-H "Authorization: Bearer ${JWT}" \
|
|
-H "Accept: application/vnd.github+json" \
|
|
-H "X-GitHub-Api-Version: 2022-11-28" \
|
|
"https://api.github.com/app/installations/${GITHUB_APP_INSTALLATION_ID}/access_tokens") \
|
|
|| die "GitHub API request failed — check App ID, Installation ID, and PEM key"
|
|
|
|
TOKEN=$(echo "$RESPONSE" | jq -r '.token // empty')
|
|
[[ -z "$TOKEN" ]] && die "No token in GitHub response: $RESPONSE"
|
|
|
|
# --- Resolve token file location ---
|
|
# Prefer GH_CONFIG_DIR (so the token lives alongside the per-agent gh config),
|
|
# fall back to AGENT_HOME, fail loudly if neither is set rather than silently
|
|
# writing to /tmp and leaking the token.
|
|
if [[ -n "${GH_CONFIG_DIR:-}" ]]; then
|
|
GH_TOKEN_DIR="$GH_CONFIG_DIR"
|
|
elif [[ -n "${AGENT_HOME:-}" ]]; then
|
|
GH_TOKEN_DIR="$AGENT_HOME"
|
|
else
|
|
die "Neither GH_CONFIG_DIR nor AGENT_HOME is set — refusing to write the token to a default location"
|
|
fi
|
|
|
|
mkdir -p "$GH_TOKEN_DIR"
|
|
GH_TOKEN_FILE="$GH_TOKEN_DIR/.gh-token"
|
|
|
|
# Validate GH_CONFIG_DIR is inside AGENT_HOME (prevents writing the token to a foreign workspace)
|
|
if [[ -n "${GH_CONFIG_DIR:-}" && -n "${AGENT_HOME:-}" && "$GH_CONFIG_DIR" != "$AGENT_HOME"* ]]; then
|
|
die "GH_CONFIG_DIR '$GH_CONFIG_DIR' is outside AGENT_HOME '${AGENT_HOME}'. Refusing to write token to a foreign workspace."
|
|
fi
|
|
|
|
printf '%s' "$TOKEN" > "$GH_TOKEN_FILE"
|
|
chmod 600 "$GH_TOKEN_FILE"
|
|
|
|
# --- Authenticate gh CLI ---
|
|
GH_CONFIG_DIR="$GH_TOKEN_DIR" gh auth login --with-token < "$GH_TOKEN_FILE"
|
|
|
|
echo "Authenticated. Token written to $GH_TOKEN_FILE (expires in 1 hour)."
|