zeroinstall/injector/trust.py

   1 """
   2 Records who we trust to sign feeds.
   3
   4 Trust is divided up into domains, so that it is possible to trust a key
   5 in some cases and not others.
   6
   7 @var trust_db: Singleton trust database instance.
   8 """
   9
  10 # Copyright (C) 2009, Thomas Leonard
  11 # See the README file for details, or visit http://0install.net.
  12
  13 from zeroinstall import _, SafeException
  14 import os
  15 from logging import info
  16
  17 from zeroinstall import support
  18 from zeroinstall.support import basedir, tasks
  19 from .namespaces import config_site, config_prog, XMLNS_TRUST
  20
  21 KEY_INFO_TIMEOUT = 10   # Maximum time to wait for response from key-info-server
  22
  23 class TrustDB(object):
  24         """A database of trusted keys.
  25         @ivar keys: maps trusted key fingerprints to a set of domains for which where it is trusted
  26         @type keys: {str: set(str)}
  27         @ivar watchers: callbacks invoked by L{notify}
  28         @see: L{trust_db} - the singleton instance of this class"""
  29         __slots__ = ['keys', 'watchers']
  30
  31         def __init__(self):
  32                 self.keys = None
  33                 self.watchers = []
  34
  35         def is_trusted(self, fingerprint, domain = None):
  36                 self.ensure_uptodate()
  37
  38                 domains = self.keys.get(fingerprint, None)
  39                 if not domains: return False    # Unknown key
  40
  41                 if domain is None:
  42                         return True             # Deprecated
  43
  44                 return domain in domains or '*' in domains
  45
  46         def get_trust_domains(self, fingerprint):
  47                 """Return the set of domains in which this key is trusted.
  48                 If the list includes '*' then the key is trusted everywhere.
  49                 @since: 0.27
  50                 """
  51                 self.ensure_uptodate()
  52                 return self.keys.get(fingerprint, set())
  53
  54         def get_keys_for_domain(self, domain):
  55                 """Return the set of keys trusted for this domain.
  56                 @since: 0.27"""
  57                 self.ensure_uptodate()
  58                 return set([fp for fp in self.keys
  59                                  if domain in self.keys[fp]])
  60
  61         def trust_key(self, fingerprint, domain = '*'):
  62                 """Add key to the list of trusted fingerprints.
  63                 @param fingerprint: base 16 fingerprint without any spaces
  64                 @type fingerprint: str
  65                 @param domain: domain in which key is to be trusted
  66                 @type domain: str
  67                 @note: call L{notify} after trusting one or more new keys"""
  68                 if self.is_trusted(fingerprint, domain): return
  69
  70                 int(fingerprint, 16)            # Ensure fingerprint is valid
  71
  72                 if fingerprint not in self.keys:
  73                         self.keys[fingerprint] = set()
  74
  75                 #if domain == '*':
  76                 #       warn("Calling trust_key() without a domain is deprecated")
  77
  78                 self.keys[fingerprint].add(domain)
  79                 self.save()
  80
  81         def untrust_key(self, key, domain = '*'):
  82                 self.ensure_uptodate()
  83                 self.keys[key].remove(domain)
  84
  85                 if not self.keys[key]:
  86                         # No more domains for this key
  87                         del self.keys[key]
  88
  89                 self.save()
  90
  91         def save(self):
  92                 from xml.dom import minidom
  93                 import tempfile
  94
  95                 doc = minidom.Document()
  96                 root = doc.createElementNS(XMLNS_TRUST, 'trusted-keys')
  97                 root.setAttribute('xmlns', XMLNS_TRUST)
  98                 doc.appendChild(root)
  99
 100                 for fingerprint in self.keys:
 101                         keyelem = doc.createElementNS(XMLNS_TRUST, 'key')
 102                         root.appendChild(keyelem)
 103                         keyelem.setAttribute('fingerprint', fingerprint)
 104                         for domain in self.keys[fingerprint]:
 105                                 domainelem = doc.createElementNS(XMLNS_TRUST, 'domain')
 106                                 domainelem.setAttribute('value', domain)
 107                                 keyelem.appendChild(domainelem)
 108
 109                 d = basedir.save_config_path(config_site, config_prog)
 110                 fd, tmpname = tempfile.mkstemp(dir = d, prefix = 'trust-')
 111                 tmp = os.fdopen(fd, 'wb')
 112                 doc.writexml(tmp, indent = "", addindent = "  ", newl = "\n")
 113                 tmp.close()
 114
 115                 support.portable_rename(tmpname, os.path.join(d, 'trustdb.xml'))
 116
 117         def notify(self):
 118                 """Call all watcher callbacks.
 119                 This should be called after trusting or untrusting one or more new keys.
 120                 @since: 0.25"""
 121                 for w in self.watchers: w()
 122
 123         def ensure_uptodate(self):
 124                 from xml.dom import minidom
 125
 126                 # This is a bit inefficient... (could cache things)
 127                 self.keys = {}
 128
 129                 trust = basedir.load_first_config(config_site, config_prog, 'trustdb.xml')
 130                 if trust:
 131                         keys = minidom.parse(trust).documentElement
 132                         for key in keys.getElementsByTagNameNS(XMLNS_TRUST, 'key'):
 133                                 domains = set()
 134                                 self.keys[key.getAttribute('fingerprint')] = domains
 135                                 for domain in key.getElementsByTagNameNS(XMLNS_TRUST, 'domain'):
 136                                         domains.add(domain.getAttribute('value'))
 137                 else:
 138                         # Convert old database to XML format
 139                         trust = basedir.load_first_config(config_site, config_prog, 'trust')
 140                         if trust:
 141                                 #print "Loading trust from", trust_db
 142                                 for key in open(trust).read().split('\n'):
 143                                         if key:
 144                                                 self.keys[key] = set(['*'])
 145                         else:
 146                                 # No trust database found.
 147                                 # Trust Thomas Leonard's key for 0install.net by default.
 148                                 # Avoids distracting confirmation box on first run when we check
 149                                 # for updates to the GUI.
 150                                 self.keys['92429807C9853C0744A68B9AAE07828059A53CC1'] = set(['0install.net'])
 151
 152 def domain_from_url(url):
 153         """Extract the trust domain for a URL.
 154         @param url: the feed's URL
 155         @type url: str
 156         @return: the trust domain
 157         @rtype: str
 158         @since: 0.27
 159         @raise SafeException: the URL can't be parsed"""
 160         import urlparse
 161         if os.path.isabs(url):
 162                 raise SafeException(_("Can't get domain from a local path: '%s'") % url)
 163         domain = urlparse.urlparse(url)[1]
 164         if domain and domain != '*':
 165                 return domain
 166         raise SafeException(_("Can't extract domain from URL '%s'") % url)
 167
 168 trust_db = TrustDB()
 169
 170 class TrustMgr(object):
 171         """A TrustMgr handles the process of deciding whether to trust new keys
 172         (contacting the key information server, prompting the user, accepting automatically, etc)
 173         @since: 0.53"""
 174
 175         __slots__ = ['config', '_current_confirm']
 176
 177         def __init__(self, config):
 178                 self.config = config
 179                 self._current_confirm = None    # (a lock to prevent asking the user multiple questions at once)
 180
 181         @tasks.async
 182         def confirm_keys(self, pending):
 183                 """We don't trust any of the signatures yet. Collect information about them and add the keys to the
 184                 trusted list, possibly after confirming with the user (via config.handler).
 185                 Updates the L{trust} database, and then calls L{trust.TrustDB.notify}.
 186                 @since: 0.53
 187                 @arg pending: an object holding details of the updated feed
 188                 @type pending: L{PendingFeed}
 189                 @return: A blocker that triggers when the user has chosen, or None if already done.
 190                 @rtype: None | L{Blocker}"""
 191
 192                 assert pending.sigs
 193
 194                 from zeroinstall.injector import gpg
 195                 valid_sigs = [s for s in pending.sigs if isinstance(s, gpg.ValidSig)]
 196                 if not valid_sigs:
 197                         def format_sig(sig):
 198                                 msg = str(sig)
 199                                 if sig.messages:
 200                                         msg += "\nMessages from GPG:\n" + sig.messages
 201                                 return msg
 202                         raise SafeException(_('No valid signatures found on "%(url)s". Signatures:%(signatures)s') %
 203                                         {'url': pending.url, 'signatures': ''.join(['\n- ' + format_sig(s) for s in pending.sigs])})
 204
 205                 # Start downloading information about the keys...
 206                 fetcher = self.config.fetcher
 207                 kfs = {}
 208                 for sig in valid_sigs:
 209                         kfs[sig] = fetcher.fetch_key_info(sig.fingerprint)
 210
 211                 # Wait up to KEY_INFO_TIMEOUT seconds for key information to arrive. Avoids having the dialog
 212                 # box update while the user is looking at it, and may allow it to be skipped completely in some
 213                 # cases.
 214                 timeout = tasks.TimeoutBlocker(KEY_INFO_TIMEOUT, "key info timeout")
 215                 while True:
 216                         key_info_blockers = [sig_info.blocker for sig_info in kfs.values() if sig_info.blocker is not None]
 217                         if not key_info_blockers:
 218                                 break
 219                         info("Waiting for response from key-info server: %s", key_info_blockers)
 220                         yield [timeout] + key_info_blockers
 221                         if timeout.happened:
 222                                 info("Timeout waiting for key info response")
 223                                 break
 224
 225                 # If we're already confirming something else, wait for that to finish...
 226                 while self._current_confirm is not None:
 227                         info("Waiting for previous key confirmations to finish")
 228                         yield self._current_confirm
 229
 230                 domain = domain_from_url(pending.url)
 231
 232                 if self.config.auto_approve_keys:
 233                         existing_feed = self.config.iface_cache.get_feed(pending.url)
 234                         if not existing_feed:
 235                                 changes = False
 236                                 for sig, kf in kfs.items():
 237                                         for key_info in kf.info:
 238                                                 if key_info.getAttribute("vote") == "good":
 239                                                         info(_("Automatically approving key for new feed %s based on response from key info server"), pending.url)
 240                                                         trust_db.trust_key(sig.fingerprint, domain)
 241                                                         changes = True
 242                                 if changes:
 243                                         trust_db.notify()
 244
 245                 # Check whether we still need to confirm. The user may have
 246                 # already approved one of the keys while dealing with another
 247                 # feed, or we may have just auto-approved it.
 248                 for sig in kfs:
 249                         is_trusted = trust_db.is_trusted(sig.fingerprint, domain)
 250                         if is_trusted:
 251                                 return
 252
 253                 # Take the lock and confirm this feed
 254                 self._current_confirm = lock = tasks.Blocker('confirm key lock')
 255                 try:
 256                         done = self.config.handler.confirm_import_feed(pending, kfs)
 257                         if done is not None:
 258                                 yield done
 259                                 tasks.check(done)
 260                 finally:
 261                         self._current_confirm = None
 262                         lock.trigger()