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Garry TanandClaude Fable 5
455c805125
Freeze boundary hook had four verified bugs: the grep-first JSON extractor truncated at escaped quotes and failed OPEN on unparseable payloads; the deny JSON was printf-interpolated so a quote- or newline-bearing path silently no-oped the block; the freeze path read stripped INTERNAL spaces (a boundary like ~/My Project could never match); and the path resolver skipped the final component, letting an in-boundary symlink write through to an out-of-boundary target. Fixes, structurally: one shared sourced helper (careful/bin/hook-extract.sh) now owns JSON extraction and JSON-encoded decision envelopes for BOTH hooks -- the two-copy drift is how freeze kept a broken extractor after careful's was fixed. Freeze is now deny-tier fail-closed (unparseable payload denies, parsed-but-no-file_path still allows), trims only leading/trailing whitespace, and resolves symlinks through the final path component. Careful gains a HIGH tier (hard deny, simple commands only): recursive delete of /, ~, or $HOME, and force-push to the repo's default branch. Compound commands always fall through to the MEDIUM ask; --force-with-lease is never HIGH. Documented as a best-effort advisory hard-stop, not a policy boundary. Plus additive-only project patterns (~/.gstack/careful-patterns.txt + per-project file): config can only ADD warn rules, never suppress a baseline family. test/hook-scripts.test.ts: 89 tests incl. malformed-payload deny, parseable deny JSON for hostile paths, space-bearing boundaries, symlink escape, HIGH tier splits, additive invariant, invalid-regex resilience. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
121 lines
4.7 KiB
Bash
Executable File
121 lines
4.7 KiB
Bash
Executable File
#!/usr/bin/env bash
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# check-freeze.sh — PreToolUse hook for /freeze skill
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# Reads JSON from stdin, checks if file_path is within the freeze boundary.
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# Returns a PreToolUse hookSpecificOutput with permissionDecision "deny" to block,
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# or {} to allow. The decision MUST be nested under hookSpecificOutput — Claude
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# Code ignores a top-level permissionDecision, which silently no-ops the block.
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#
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# Polarity: freeze is a DENY-tier hook, so an unreadable payload DENIES
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# (fail closed). A payload that parses but has no file_path is a non-file
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# tool — allow. This is the opposite edge-handling from careful's ask-tier
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# and intentionally so: /guard runs both, and a boundary that fails open is
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# not a boundary.
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set -euo pipefail
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# Read stdin
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INPUT=$(cat)
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# Shared JSON helpers (extractor + encoder) — one copy for careful AND freeze.
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# freeze previously carried its own grep-first extractor which truncated at
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# escaped quotes and failed OPEN; the shared file kills that drift class.
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_HOOK_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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# shellcheck source=careful/bin/hook-extract.sh
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. "$_HOOK_DIR/../../careful/bin/hook-extract.sh"
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# Locate the freeze directory state file
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STATE_DIR="${CLAUDE_PLUGIN_DATA:-$HOME/.gstack}"
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FREEZE_FILE="$STATE_DIR/freeze-dir.txt"
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# If no freeze file exists, allow everything (not yet configured)
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if [ ! -f "$FREEZE_FILE" ]; then
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echo '{}'
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exit 0
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fi
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# First line, trimmed of LEADING/TRAILING whitespace only. The previous
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# `tr -d '[:space:]'` deleted INTERNAL spaces too, so a boundary like
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# "~/My Project/src" could never match anything — every edit denied (or the
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# mangled path accidentally allowed the wrong tree).
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FREEZE_DIR=$(head -n 1 "$FREEZE_FILE" 2>/dev/null | sed 's/^[[:space:]]*//;s/[[:space:]]*$//')
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# If freeze dir is empty, allow
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if [ -z "$FREEZE_DIR" ]; then
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echo '{}'
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exit 0
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fi
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# Extract file_path from tool_input with the shared real-JSON parser.
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set +e
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FILE_PATH=$(gstack_hook_extract_field "$INPUT" file_path)
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EXTRACT_RC=$?
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set -e
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# Unparseable payload (or no parser available): DENY. A boundary hook that
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# allows what it cannot read is not a boundary.
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if [ "$EXTRACT_RC" -ne 0 ] && [ -n "$INPUT" ]; then
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gstack_hook_decision deny "[freeze] Could not parse the tool payload to check the freeze boundary. Blocked (fail closed). Freeze boundary: $FREEZE_DIR"
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exit 0
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fi
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# Parsed fine but no file_path field: a non-file tool payload — allow.
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if [ -z "$FILE_PATH" ]; then
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echo '{}'
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exit 0
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fi
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# Resolve file_path to absolute if it isn't already
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case "$FILE_PATH" in
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/*) ;; # already absolute
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*)
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FILE_PATH="$(pwd)/$FILE_PATH"
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;;
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esac
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# Normalize: remove double slashes and trailing slash
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FILE_PATH=$(printf '%s' "$FILE_PATH" | sed 's|/\+|/|g;s|/$||')
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# Resolve symlinks and .. sequences (POSIX-portable, works on macOS).
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# The FULL path is resolved, including the FINAL component: the previous
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# version resolved only the parent directory, so an in-boundary symlink
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# pointing at an out-of-boundary target sailed through the check while the
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# actual write landed outside the boundary. A final component that is a
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# symlink is followed (bounded, cycle-safe) so the TARGET gets checked; a
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# final component that does not exist yet (new file) has nothing to follow
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# and parent resolution is the correct behavior.
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_resolve_path() {
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local _p="$1" _dir _base _tgt _i=0
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while [ -L "$_p" ] && [ "$_i" -lt 40 ]; do
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_tgt=$(readlink "$_p" 2>/dev/null) || break
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case "$_tgt" in
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/*) _p="$_tgt" ;;
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*) _p="$(dirname "$_p")/$_tgt" ;;
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esac
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_i=$((_i + 1))
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done
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_dir="$(dirname "$_p")"
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_base="$(basename "$_p")"
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_dir="$(cd "$_dir" 2>/dev/null && pwd -P || printf '%s' "$_dir")"
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printf '%s/%s' "$_dir" "$_base"
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}
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FILE_PATH=$(_resolve_path "$FILE_PATH")
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FREEZE_DIR=$(_resolve_path "$FREEZE_DIR")
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# Check: does the file path start with the freeze directory?
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case "$FILE_PATH" in
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"${FREEZE_DIR}/"*|"${FREEZE_DIR}")
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# Inside freeze boundary — allow
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echo '{}'
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;;
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*)
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# Outside freeze boundary — deny
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# Log hook fire event
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mkdir -p ~/.gstack/analytics 2>/dev/null || true
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echo '{"event":"hook_fire","skill":"freeze","pattern":"boundary_deny","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}' >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true
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# The reason is JSON-encoded by the shared helper. Never interpolate paths
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# into hand-built JSON: a path containing a quote or newline produced
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# malformed JSON here, and the deny silently no-oped.
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gstack_hook_decision deny "[freeze] Blocked: $FILE_PATH is outside the freeze boundary ($FREEZE_DIR). Only edits within the frozen directory are allowed."
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;;
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esac
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