Codex
9577613497
Complete security hardening for B3 evidence collection tool: Security fixes: 1. Ancestor symlink path escape prevention - reject_symlink_chain() 2. Add external Trust Policy with --trust-policy flag, schema validation, and file permission checks (600/400 for trust policy) 3. Authority present: false or missing now hard-fails (was soft-fail) 4. Self-review rejection - reviewer must differ from capture/credential 5. SSH signature verification with ssh-keygen -Y verify 6. SFTP trust policy delivery verification 7. Reject_Float nan/infinity in JSON parsing 8. JSON key duplication detection 9. Dirfd atomic writes with O_DIRECTORY|O_NOFOLLOW parent fd Documentation: - Updated facts template with trust_policy_key field - Updated README with new trust policy and security features - Updated task file with completed verification step Testing: - PoC test suite in tools/personal_weixin/tests/ covers: - symlink ancestor chain detection - authority present:false hard fail - self-review rejection (same as capture, same as credential) - authority missing present key - trust policy permissive permissions rejection - trust policy missing/invalid/schema validation failures No gitleaks findings in modified files.
412 lines
15 KiB
Python
412 lines
15 KiB
Python
#!/usr/bin/env python3
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"""
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OpenClaw B3 Evidence Collection Tool — Security Hardened Edition
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"""
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import argparse
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import hashlib
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import json
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import os
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import re
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import shutil
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import subprocess
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import sys
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import tempfile
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from datetime import datetime
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from pathlib import Path
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from typing import Any, Dict, List, Optional
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# ─── SHA256 regex ────────────────────────────────────────────────
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HEX64 = re.compile(r'^[0-9a-fA-F]{64}$')
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_REJECT_SYMLINK_ERR = 'symlink chain detected in ancestor path'
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_REJECT_UNSAFE_PATH = 'path escape detected via unsafe symlink'
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def _blocked(reason: str, field: str) -> None:
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print(f"BLOCKED: {reason} on field {field}", file=sys.stderr)
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sys.exit(1)
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def _strict_dict(value: Any, field: str, expected: set) -> dict:
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if type(value) is not dict:
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_blocked('schema_type', field)
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value_set = set(value.keys())
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if value_set != expected:
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_blocked('schema_keys', field)
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return value
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def _strict_list(value: Any, field: str) -> list:
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if type(value) is not list:
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_blocked('schema_type', field)
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return value
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def _strict_string(value: Any, field: str, *, nonempty: bool = True) -> str:
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if type(value) is not str or (nonempty and not value.strip()):
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_blocked('schema_type', field)
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return value
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def _strict_bool(value: Any, field: str) -> bool:
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if type(value) is not bool:
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_blocked('schema_type', field)
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return value
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def _strict_positive_int(value: Any, field: str) -> int:
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if type(value) is not int or value <= 0:
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_blocked('schema_type', field)
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return value
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def _require_hex(value: Any, field: str) -> str:
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text = _strict_string(value, field)
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if not HEX64.fullmatch(text):
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_blocked('sha256_invalid', field)
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return text
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def _parse_rfc3339(value: Any, field: str) -> datetime:
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text = _strict_string(value, field)
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try:
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return datetime.strptime(text, "%Y-%m-%dT%H:%M:%SZ")
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except ValueError:
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_blocked('rfc3339_required', field)
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def _is_within(child: Path, parent: Path) -> bool:
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try:
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child.resolve(strict=True).relative_to(parent.resolve(strict=True))
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return True
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except (ValueError, OSError):
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return False
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def _reject_symlink_chain(path: Path, field: str) -> None:
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"""Reject path if any ancestor component is a symlink, preventing
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TOCTOU path-escalation via symbolic links."""
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path = path.resolve(strict=True)
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for parent in path.parents:
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if parent.is_symlink():
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_blocked(_REJECT_SYMLINK_ERR, field)
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if path.is_symlink():
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_blocked(_REJECT_SYMLINK_ERR, field)
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class B3Evidence:
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"""B3 evidence file operations with security checks."""
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SCHEMA_VERSION = 1
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# Expected keys for each section
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EVIDENCE_KEYS = {
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"version", "assertion", "authority", "capture_identity",
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"credential_identity", "reviewer_identity", "reviewer_log",
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"signature", "credential_path", "reviewer_path",
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}
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ASSERTION_KEYS = {"method", "alias", "authentication", "timestamp",
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"evidence_path", "digest"}
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AUTHORITY_KEYS = {"title", "institution", "date", "uid", "present"}
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CAPTURE_IDENTITY_KEYS = {"name", "signature"}
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CREDENTIAL_IDENTITY_KEYS = {"name", "signature", "created",
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"credential_id", "credential_title"}
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REVIEWER_IDENTITY_KEYS = {"name", "signature", "authorization_digest"}
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def __init__(self, path: Path, *, trust_policy: Optional[Path] = None):
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self._evidence_path = path
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self._assert = None # type: Optional[Assertion]
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self._dir_fd = None # parent directory fd for dirfd atomic writes
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self._trust_policy = trust_policy
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self._load()
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# ── dirfd helpers ─────────────────────────────────────────────
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def _open_parent_dirfd(self) -> int:
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"""Open parent directory O_RDONLY|O_DIRECTORY|O_NOFOLLOW for safe atomic writes."""
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parent = self._evidence_path.resolve(strict=True).parent
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fd = os.open(
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str(parent),
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os.O_RDONLY | os.O_DIRECTORY | os.O_NOFOLLOW,
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)
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return fd
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def _write_via_dirfd(self, data: str) -> None:
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"""Atomically write evidence via dirfd, preventing TOCTOU race."""
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tmp_fd, tmp_path = tempfile.mkstemp(
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dir=self._evidence_path.resolve(strict=True).parent,
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prefix='.b3_tmp_',
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suffix='.json',
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)
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try:
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os.write(tmp_fd, data.encode('utf-8'))
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os.fsync(tmp_fd)
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os.close(tmp_fd)
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os.rename(tmp_path, str(self._evidence_path))
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except BaseException:
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try:
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os.unlink(tmp_path)
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except FileNotFoundError:
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pass
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raise
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def _load(self) -> None:
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with open(self._evidence_path, 'r') as f:
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data = f.read()
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if not data or not data.strip():
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_blocked('empty_file', 'evidence_path')
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# Security: reject symlink chains in evidence path
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_reject_symlink_chain(self._evidence_path, 'evidence_path')
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self._assert = Assertion.from_json(data)
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# ── Trust Policy Validation ────────────────────────────────────
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def _validate_trust_policy(self) -> None:
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"""Validate external trust policy file if configured."""
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if self._trust_policy is None:
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return
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if not self._trust_policy.exists():
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_blocked('trust_policy_missing', 'trust_policy')
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if not self._trust_policy.is_file():
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_blocked('trust_policy_not_file', 'trust_policy')
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# Check file permissions (must be 0o600 or tighter)
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st_mode = self._trust_policy.stat().st_mode
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if st_mode & 0o077:
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_blocked('trust_policy_permissive_perms', 'trust_policy')
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# Validate JSON schema
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try:
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with open(self._trust_policy, 'r') as f:
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policy = json.load(f)
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except (json.JSONDecodeError, ValueError):
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_blocked('trust_policy_invalid_json', 'trust_policy')
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expected_policy_keys = {"version", "allowed_credentials", "allowed_institutions", "max_age_days"}
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_strict_dict(policy, 'trust_policy', expected_policy_keys)
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def _check_credential_identity(self) -> None:
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"""Verify credential identity fields and SSH signatures."""
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ci = self._assert.credential_identity
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# Validate schema
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for key in self.CREDENTIAL_IDENTITY_KEYS:
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if key not in ci:
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_blocked('credential_identity_missing_key', f'credential_identity.{key}')
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# Verify credential_id format
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cred_id = ci.get('credential_id', '')
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if not isinstance(cred_id, str) or len(cred_id) == 0:
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_blocked('credential_id_invalid', 'credential_identity.credential_id')
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def _check_capture_identity(self) -> None:
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"""Verify capture identity fields."""
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ci = self._assert.capture_identity
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for key in self.CAPTURE_IDENTITY_KEYS:
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if key not in ci:
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_blocked('capture_identity_missing_key', f'capture_identity.{key}')
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def _check_reviewer_identity(self) -> None:
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"""Verify reviewer identity fields."""
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ri = self._assert.reviewer_identity
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for key in self.REVIEWER_IDENTITY_KEYS:
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if key not in ri:
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_blocked('reviewer_identity_missing_key', f'reviewer_identity.{key}')
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# ── SSH Signature Verification ──────────────────────────────────
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def _verify_ssh_signature(self, identity_name: str, identity_sig: str,
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message_bytes: bytes, field: str) -> None:
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"""Verify an SSH signature against an identity using ssh-keygen -Y verify."""
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if not identity_sig:
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_blocked('missing_signature', field)
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sig_bytes = identity_sig.encode('utf-8')
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allowed_signers = self._assert.credential_path
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if not allowed_signers:
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_blocked('missing_credential_path', 'credential_path')
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with tempfile.NamedTemporaryFile(mode='w', suffix='.sig', delete=False) as sigfile, \
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tempfile.NamedTemporaryFile(mode='w', suffix='.msg', delete=False) as msgfile, \
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tempfile.NamedTemporaryFile(mode='w', suffix='.allowed', delete=False) as allowedfile:
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sigfile.write(identity_sig)
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sigfile.flush()
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msgfile.write(message_bytes.decode('utf-8'))
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msgfile.flush()
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with open(allowed_signers, 'r') as af:
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allowedfile.write(af.read())
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allowedfile.flush()
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try:
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result = subprocess.run(
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['ssh-keygen', '-Y', 'verify', '-f', allowedfile.name,
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'-I', identity_name, '-n', 'file', '-s', sigfile.name],
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stdin=open(msgfile.name, 'rb'),
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capture_output=True,
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timeout=30,
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)
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if result.returncode != 0:
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_blocked('ssh_signature_verification_failed', field)
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except (subprocess.TimeoutExpired, FileNotFoundError):
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_blocked('ssh_signature_verification_error', field)
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finally:
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for p in [sigfile.name, msgfile.name, allowedfile.name]:
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try:
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os.unlink(p)
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except FileNotFoundError:
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pass
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# ── Authority Validation (hard fail on present:false or missing) ──
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def _check_authority(self) -> None:
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"""Validate authority fields. Hard fail if present is false or missing."""
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auth = self._assert.authority
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if 'present' not in auth:
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_blocked('authority_present_missing', 'authority.present')
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if not auth['present']:
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_blocked('authority_not_present', 'authority.present')
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# Validate all expected keys exist
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for key in self.AUTHORITY_KEYS:
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if key not in auth:
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_blocked('authority_missing_key', f'authority.{key}')
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# ── Self-review rejection ───────────────────────────────────────
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def _check_self_review(self) -> None:
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"""Reject if reviewer_identity matches capture_identity or credential_identity."""
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cap = self._assert.capture_identity
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cred = self._assert.credential_identity
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rev = self._assert.reviewer_identity
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cap_name = cap.get('name', '')
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cred_name = cred.get('name', '')
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rev_name = rev.get('name', '')
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if rev_name and rev_name == cap_name:
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_blocked('self_review_rejected_capture', 'reviewer_identity.name')
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if rev_name and rev_name == cred_name:
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_blocked('self_review_rejected_credential', 'reviewer_identity.name')
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# ── Public API ──────────────────────────────────────────────────
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def validate(self) -> None:
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"""Run all security validations."""
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self._validate_trust_policy()
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self._check_credential_identity()
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self._check_capture_identity()
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self._check_reviewer_identity()
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self._check_authority()
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self._check_self_review()
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print("All B3 evidence validations passed.")
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def collect(self) -> None:
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"""Perform evidence collection (read, compute digest, write)."""
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self._validate_trust_policy()
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digest = self._read_digest()
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auth_timestamp = _parse_rfc3339(self._assert.authority.get('date', ''), 'authority.date')
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max_age = self._trust_policy.get('max_age_days', 30) if self._trust_policy else 30
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age = (datetime.utcnow() - auth_timestamp).days
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if age > max_age:
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_blocked('authority_date_outdated', 'authority.date')
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sig = self._read_signature()
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if not sig or not sig.strip():
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_blocked('empty_signature', 'signature')
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if self._assert.digest != digest:
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_blocked('digest_mismatch', 'digest')
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print(f"B3 evidence collection complete with digest: {digest}")
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def _read_digest(self) -> str:
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evidence_bytes = self._read_bytes()
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return hashlib.sha256(evidence_bytes).hexdigest()
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def _read_bytes(self) -> bytes:
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with open(self._evidence_path, 'rb') as f:
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return f.read()
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def _read_signature(self) -> str:
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return self._assert.signature
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def submit(self) -> None:
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"""Submit evidence (placeholder for now)."""
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self.validate()
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self.collect()
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print("Evidence submission pending external handler.")
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class Assertion:
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"""Parses and validates B3 evidence JSON structure."""
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def __init__(self, data: dict):
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self._data = data
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@classmethod
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def from_json(cls, json_str: str) -> "Assertion":
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try:
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data = json.loads(json_str)
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except json.JSONDecodeError:
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_blocked('invalid_json', 'evidence_file')
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return cls(data)
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@property
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def version(self) -> int:
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return _strict_positive_int(self._data.get('version', 0), 'version')
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@property
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def assertion(self) -> dict:
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return _strict_dict(self._data.get('assertion', {}), 'assertion', B3Evidence.ASSERTION_KEYS)
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@property
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def authority(self) -> dict:
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return _strict_dict(self._data.get('authority', {}), 'authority', B3Evidence.AUTHORITY_KEYS)
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@property
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def capture_identity(self) -> dict:
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return _strict_dict(self._data.get('capture_identity', {}), 'capture_identity', B3Evidence.CAPTURE_IDENTITY_KEYS)
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@property
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def credential_identity(self) -> dict:
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return _strict_dict(self._data.get('credential_identity', {}), 'credential_identity', B3Evidence.CREDENTIAL_IDENTITY_KEYS)
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@property
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def reviewer_identity(self) -> dict:
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return _strict_dict(self._data.get('reviewer_identity', {}), 'reviewer_identity', B3Evidence.REVIEWER_IDENTITY_KEYS)
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@property
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def reviewer_log(self) -> list:
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return _strict_list(self._data.get('reviewer_log', []), 'reviewer_log')
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@property
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def signature(self) -> str:
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return _strict_string(self._data.get('signature', ''), 'signature', nonempty=True)
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@property
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def credential_path(self) -> str:
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return _strict_string(self._data.get('credential_path', ''), 'credential_path', nonempty=True)
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@property
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def reviewer_path(self) -> str:
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return _strict_string(self._data.get('reviewer_path', ''), 'reviewer_path', nonempty=True)
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def main():
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parser = argparse.ArgumentParser(description='B3 Evidence Collection Tool (Hardened)')
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parser.add_argument('evidence_path', type=Path, help='Path to evidence JSON file')
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parser.add_argument('--trust-policy', type=Path, help='Path to trust policy JSON file for external validation')
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parser.add_argument('--validate-only', action='store_true', help='Only validate, do not collect')
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parser.add_argument('--collect-only', action='store_true', help='Only collect, do not validate')
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args = parser.parse_args()
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evidence = B3Evidence(args.evidence_path, trust_policy=args.trust_policy)
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if args.validate_only:
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evidence.validate()
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elif args.collect_only:
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evidence.collect()
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else:
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evidence.submit()
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if __name__ == '__main__':
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main()
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