Patchwork [4,of,9,V3] sslutil: add devel.disableloaddefaultcerts to disable CA loading

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Submitter Gregory Szorc
Date June 2, 2016, 3:16 a.m.
Message ID <a2878fbb2db7d6bc2737.1464837378@ubuntu-vm-main>
Download mbox | patch
Permalink /patch/15330/
State Superseded
Delegated to: Yuya Nishihara
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Gregory Szorc - June 2, 2016, 3:16 a.m.
# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 1464836240 25200
#      Wed Jun 01 19:57:20 2016 -0700
# Node ID a2878fbb2db7d6bc273721dba95cf8a2ac159e3e
# Parent  65dda98b19d7c20dbd25086e05b4a535e2099f86
sslutil: add devel.disableloaddefaultcerts to disable CA loading

There are various tests for behavior when CA certs aren't loaded.
Previously, we would pass --insecure to disable loading of CA
certs. This has worked up to this point because the error message
for --insecure and no CAs loaded is the same. Upcoming commits will
change the error message for --insecure and will change behavior
when CAs aren't loaded.

This commit introduces the ability to disable loading of CA certs
by setting devel.disableloaddefaultcerts. This allows a testing
backdoor to disable loading of CA certs even if system/default
CA certs are available. The flag is purposefully not exposed to
end-users because there should not be a need for this in the wild:
certificate pinning and --insecure provide workarounds to disable
cert loading/validation.

Tests have been updated to use the new method. The variable used
to disable CA certs has been renamed because the method is not
OS X specific.

Patch

diff --git a/mercurial/sslutil.py b/mercurial/sslutil.py
--- a/mercurial/sslutil.py
+++ b/mercurial/sslutil.py
@@ -107,16 +107,19 @@  except AttributeError:
             return ssl.wrap_socket(socket, **args)
 
 def _hostsettings(ui, hostname):
     """Obtain security settings for a hostname.
 
     Returns a dict of settings relevant to that hostname.
     """
     s = {
+        # Whether we should attempt to load default/available CA certs
+        # if an explicit ``cafile`` is not defined.
+        'allowloaddefaultcerts': True,
         # List of 2-tuple of (hash algorithm, hash).
         'certfingerprints': [],
         # Path to file containing concatenated CA certs. Used by
         # SSLContext.load_verify_locations().
         'cafile': None,
         # Whether certificate verification should be disabled.
         'disablecertverification': False,
         # Whether the legacy [hostfingerprints] section has data for this host.
@@ -151,16 +154,19 @@  def _hostsettings(ui, hostname):
     if s['certfingerprints']:
         s['verifymode'] = ssl.CERT_NONE
 
     # If --insecure is used, don't take CAs into consideration.
     elif ui.insecureconnections:
         s['disablecertverification'] = True
         s['verifymode'] = ssl.CERT_NONE
 
+    if ui.configbool('devel', 'disableloaddefaultcerts'):
+        s['allowloaddefaultcerts'] = False
+
     # Try to hook up CA certificate validation unless something above
     # makes it not necessary.
     if s['verifymode'] is None:
         # Find global certificates file in config.
         cafile = ui.config('web', 'cacerts')
 
         if cafile:
             cafile = util.expandpath(cafile)
@@ -171,17 +177,17 @@  def _hostsettings(ui, hostname):
             cafile = _defaultcacerts()
             if cafile:
                 ui.debug('using %s to enable OS X system CA\n' % cafile)
 
         s['cafile'] = cafile
 
         # Require certificate validation if CA certs are being loaded and
         # verification hasn't been disabled above.
-        if cafile or _canloaddefaultcerts:
+        if cafile or (_canloaddefaultcerts and s['allowloaddefaultcerts']):
             s['verifymode'] = ssl.CERT_REQUIRED
         else:
             # At this point we don't have a fingerprint, aren't being
             # explicitly insecure, and can't load CA certs. Connecting
             # at this point is insecure. But we do it for BC reasons.
             # TODO abort here to make secure by default.
             s['verifymode'] = ssl.CERT_NONE
 
@@ -238,20 +244,22 @@  def wrapsocket(sock, keyfile, certfile, 
         def password():
             f = keyfile or certfile
             return ui.getpass(_('passphrase for %s: ') % f, '')
         sslcontext.load_cert_chain(certfile, keyfile, password)
 
     if settings['cafile'] is not None:
         sslcontext.load_verify_locations(cafile=settings['cafile'])
         caloaded = True
-    else:
+    elif settings['allowloaddefaultcerts']:
         # This is a no-op on old Python.
         sslcontext.load_default_certs()
-        caloaded = _canloaddefaultcerts
+        caloaded = True
+    else:
+        caloaded = False
 
     sslsocket = sslcontext.wrap_socket(sock, server_hostname=serverhostname)
     # check if wrap_socket failed silently because socket had been
     # closed
     # - see http://bugs.python.org/issue13721
     if not sslsocket.cipher():
         raise error.Abort(_('ssl connection failed'))
 
diff --git a/tests/test-https.t b/tests/test-https.t
--- a/tests/test-https.t
+++ b/tests/test-https.t
@@ -157,31 +157,30 @@  Test server address cannot be reused
   [255]
 #else
   $ hg serve -p $HGPORT --certificate=$PRIV 2>&1
   abort: cannot start server at ':$HGPORT': Address already in use
   [255]
 #endif
   $ cd ..
 
-OS X has a dummy CA cert that enables use of the system CA store when using
-Apple's OpenSSL. This trick do not work with plain OpenSSL.
+Our test cert is not signed by a trusted CA. It should fail to verify if
+we are able to load CA certs.
 
-  $ DISABLEOSXDUMMYCERT=
 #if defaultcacerts
   $ hg clone https://localhost:$HGPORT/ copy-pull
   abort: error: *certificate verify failed* (glob)
   [255]
+#endif
 
-  $ DISABLEOSXDUMMYCERT="--insecure"
-#endif
+  $ DISABLECACERTS="--config devel.disableloaddefaultcerts=true"
 
 clone via pull
 
-  $ hg clone https://localhost:$HGPORT/ copy-pull $DISABLEOSXDUMMYCERT
+  $ hg clone https://localhost:$HGPORT/ copy-pull $DISABLECACERTS
   warning: localhost certificate with fingerprint 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca not verified (check hostsecurity or web.cacerts config setting)
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 4 changes to 4 files
   updating to branch default
   4 files updated, 0 files merged, 0 files removed, 0 files unresolved
@@ -197,17 +196,17 @@  clone via pull
   adding bar
   $ cd ..
 
 pull without cacert
 
   $ cd copy-pull
   $ echo '[hooks]' >> .hg/hgrc
   $ echo "changegroup = printenv.py changegroup" >> .hg/hgrc
-  $ hg pull $DISABLEOSXDUMMYCERT
+  $ hg pull $DISABLECACERTS
   pulling from https://localhost:$HGPORT/
   warning: localhost certificate with fingerprint 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca not verified (check hostsecurity or web.cacerts config setting)
   searching for changes
   adding changesets
   adding manifests
   adding file changes
   added 1 changesets with 1 changes to 1 files
   changegroup hook: HG_NODE=5fed3813f7f5e1824344fdc9cf8f63bb662c292d HG_NODE_LAST=5fed3813f7f5e1824344fdc9cf8f63bb662c292d HG_SOURCE=pull HG_TXNID=TXN:* HG_URL=https://localhost:$HGPORT/ (glob)