key-cape/scripts/factor_recovery.py

"""Bounded provider recovery: preview, stale-state guard, disable, audit and replay."""
import hashlib,json,re

ACTION='keycape.factor.recovery'
class RecoveryError(Exception):pass

def fingerprint(snapshot):
 return hashlib.sha256(json.dumps(snapshot,sort_keys=True,separators=(',',':')).encode()).hexdigest()

def recover(store, request):
 from contextlib import nullcontext
 with store.operation_lock() if hasattr(store,"operation_lock") else nullcontext():
  return _recover(store,request)

def _recover(store, request):
 for key in ('user','serial','realm','actor','reference'):
  value=request.get(key)
  if not isinstance(value,str) or not value or len(value)>200 or not re.fullmatch(r'[A-Za-z0-9_.@:/-]+',value):raise RecoveryError('invalid_request')
 if request['realm']!=store.realm:raise RecoveryError('wrong_realm')
 snapshot=store.snapshot(request['user'],request['serial'])
 if snapshot is None:raise RecoveryError('factor_not_owned_by_target')
 version=fingerprint(snapshot)
 base={k:request[k] for k in ('user','serial','realm','actor','reference')}
 base.update(scope='shared_identity_across_applications',operation='disable_one_factor',version=version)
 if not request.get('apply'):
  return dict(base,status='preview',active=snapshot['active'],changes_applied=False)
 if request.get('identity_verified') is not True:raise RecoveryError('identity_verification_required')
 expected=request.get('expected_version')
 if not isinstance(expected,str) or not re.fullmatch(r'[0-9a-f]{64}',expected):raise RecoveryError('preview_required')
 prior=store.receipt(request['reference'])
 if prior:
  if any(prior.get(k)!=request[k] for k in ('user','serial','realm','actor')) or prior.get('version')!=expected:raise RecoveryError('reference_conflict')
  if not snapshot['active']:
   if fingerprint(dict(snapshot,active=True))!=expected:raise RecoveryError('factor_changed_after_recovery')
   if not prior['complete']:store.record(base,expected,True)
   return dict(base,status='recovered',changes_applied=False,replayed=True)
  if prior['complete']:raise RecoveryError('factor_changed_after_recovery')
 if version!=expected:raise RecoveryError('stale_preview')
 if not snapshot['active']:raise RecoveryError('factor_already_inactive')
 store.record(base,expected,False)  # An audit outage prevents mutation.
 store.disable(request['user'],request['serial'],expected)
 current=store.snapshot(request['user'],request['serial'])
 if current is None or current['active'] or fingerprint(dict(current,active=True))!=expected:raise RecoveryError('readback_failed')
 store.record(base,expected,True)
 return dict(base,status='recovered',changes_applied=True,replayed=False)

class ProviderStore:
 def __init__(self, app, realm='coulomb'):
  self.app=app;self.realm=realm
 def operation_lock(self):
  from contextlib import contextmanager
  @contextmanager
  def locked():
   from privacyidea.models import db
   from sqlalchemy import text
   if db.engine.dialect.name != 'postgresql':
    yield;return
   with db.engine.connect() as connection:
    connection.execute(text('SELECT pg_advisory_lock(4912040036)'))
    try:yield
    finally:connection.execute(text('SELECT pg_advisory_unlock(4912040036)'))
  return locked()
 def serials(self,user):
  from privacyidea.lib.token import get_tokens
  from privacyidea.lib.user import User
  values=get_tokens(user=User(user,self.realm))
  if len(values)>20:raise RecoveryError('too_many_factors')
  return [token.token.serial for token in values]
 def _token(self,user,serial):
  from privacyidea.lib.token import get_tokens
  from privacyidea.lib.user import User
  values=get_tokens(user=User(user,self.realm),serial=serial)
  if len(values)!=1:return None
  return values[0].token
 def snapshot(self,user,serial):
  token=self._token(user,serial)
  if token is None:return None
  data=token.get_vars()
  return {k:data[k] for k in ('id','serial','user_id','resolver','realms','active','rollout_state','tokentype')}
 def disable(self,user,serial,expected):
  from privacyidea.models import db,Token
  token=self._token(user,serial)
  if token is None:raise RecoveryError('factor_not_owned_by_target')
  locked=db.session.query(Token).filter(Token.id==token.id).with_for_update().one()
  db.session.refresh(locked)
  if fingerprint(self.snapshot(user,serial))!=expected:
   db.session.rollback();raise RecoveryError('stale_preview')
  locked.active=False
  db.session.commit()
 def _audit(self):
  from privacyidea.lib.audit import getAudit
  return getAudit(self.app.config)
 def receipt(self,reference):
  page=self._audit().search({'action':ACTION,'action_detail':reference},page_size=1,sortorder='desc')
  if not page.auditdata:return None
  row=page.auditdata[0]
  return {'user':row['user'],'serial':row['serial'],'realm':row['realm'],'actor':row['administrator'],'version':row['info'],'complete':bool(row['success'])}
 def record(self,request,version,complete):
  audit=self._audit()
  audit.log({'action':ACTION,'action_detail':request['reference'],'user':request['user'],'serial':request['serial'],'realm':request['realm'],'administrator':request['actor'],'info':version,'success':bool(complete)})
  audit.finalize_log()
  # Do not treat a silently failed audit append as durable evidence.
  row=self.receipt(request['reference'])
  if row is None or any(row.get(k)!=request[k] for k in ('user','serial','realm','actor')) or row['version']!=version or row['complete']!=bool(complete):raise RecoveryError('audit_unavailable')

def main():
 import contextlib,io,logging,sys
 request=json.load(sys.stdin);result={'success':False}
 with contextlib.redirect_stdout(io.StringIO()),contextlib.redirect_stderr(io.StringIO()):
  try:
   logging.disable(logging.CRITICAL)
   from privacyidea.app import create_app
   app=create_app(config_name='production',silent=True)
   with app.app_context():result=dict(recover(ProviderStore(app),request),success=True)
  except RecoveryError as e:result['failure']=str(e)
  except Exception:result['failure']='provider_operation_unavailable'
 print(json.dumps(result));return 0 if result['success'] else 1
if __name__=='__main__':raise SystemExit(main())