commit 477b1b25768945621d466a8b3f0739297a842439
author Christian Heimes <christian@python.org> Tue Jul 02 20:39:42 2019 +0200
committer Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Tue Jul 02 11:39:42 2019 -0700
tree b6e320b2a8bfad573e567855ba107fb172d4627a
parent 7cb9204ee1cf204f6f507d99a60f7c5bb359eebb

bpo-37463: match_hostname requires quad-dotted IPv4 (GH-14499)



ssl.match_hostname() no longer accepts IPv4 addresses with additional text
after the address and only quad-dotted notation without trailing
whitespaces. Some inet_aton() implementations ignore whitespace and all data
after whitespace, e.g. '127.0.0.1 whatever'.

Short notations like '127.1' for '127.0.0.1' were already filtered out.

The bug was initially found by Dominik Czarnota and reported by Paul Kehrer.

Signed-off-by: Christian Heimes <christian@python.org>



https://bugs.python.org/issue37463

Lib/ssl.py

diff --git a/Lib/ssl.py b/Lib/ssl.py
index 61bd775..0726cae 100644
--- a/Lib/ssl.py
+++ b/Lib/ssl.py
@@ -327,12 +327,22 @@
     Supports IPv4 addresses on all platforms and IPv6 on platforms with IPv6
     support.
     """
-    # inet_aton() also accepts strings like '1'
-    if ipname.count('.') == 3:
-        try:
-            return _socket.inet_aton(ipname)
-        except OSError:
-            pass
+    # inet_aton() also accepts strings like '1', '127.1', some also trailing
+    # data like '127.0.0.1 whatever'.
+    try:
+        addr = _socket.inet_aton(ipname)
+    except OSError:
+        # not an IPv4 address
+        pass
+    else:
+        if _socket.inet_ntoa(addr) == ipname:
+            # only accept injective ipnames
+            return addr
+        else:
+            # refuse for short IPv4 notation and additional trailing data
+            raise ValueError(
+                "{!r} is not a quad-dotted IPv4 address.".format(ipname)
+            )
 
     try:
         return _socket.inet_pton(_socket.AF_INET6, ipname)
@@ -346,14 +356,15 @@
     raise ValueError("{!r} is not an IPv4 address.".format(ipname))
 
 
-def _ipaddress_match(ipname, host_ip):
+def _ipaddress_match(cert_ipaddress, host_ip):
     """Exact matching of IP addresses.
 
     RFC 6125 explicitly doesn't define an algorithm for this
     (section 1.7.2 - "Out of Scope").
     """
-    # OpenSSL may add a trailing newline to a subjectAltName's IP address
-    ip = _inet_paton(ipname.rstrip())
+    # OpenSSL may add a trailing newline to a subjectAltName's IP address,
+    # commonly woth IPv6 addresses. Strip off trailing \n.
+    ip = _inet_paton(cert_ipaddress.rstrip())
     return ip == host_ip
 
 

Lib/test/test_ssl.py

diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index ef17239..d2b9e20 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -669,9 +669,14 @@
         cert = {'subject': ((('commonName', 'example.com'),),),
                 'subjectAltName': (('DNS', 'example.com'),
                                    ('IP Address', '10.11.12.13'),
-                                   ('IP Address', '14.15.16.17'))}
+                                   ('IP Address', '14.15.16.17'),
+                                   ('IP Address', '127.0.0.1'))}
         ok(cert, '10.11.12.13')
         ok(cert, '14.15.16.17')
+        # socket.inet_ntoa(socket.inet_aton('127.1')) == '127.0.0.1'
+        fail(cert, '127.1')
+        fail(cert, '14.15.16.17 ')
+        fail(cert, '14.15.16.17 extra data')
         fail(cert, '14.15.16.18')
         fail(cert, 'example.net')
 
@@ -684,6 +689,8 @@
                         ('IP Address', '2003:0:0:0:0:0:0:BABA\n'))}
             ok(cert, '2001::cafe')
             ok(cert, '2003::baba')
+            fail(cert, '2003::baba ')
+            fail(cert, '2003::baba extra data')
             fail(cert, '2003::bebe')
             fail(cert, 'example.net')