From ffbfdb53681207b23bcf67dd76368ad6185ade24 Mon Sep 17 00:00:00 2001

From: Lumir Balhar <lbalhar@redhat.com>

Date: Thu, 16 Jan 2020 07:06:09 +0100

Subject: [PATCH] Fix for CVE-2018-18074

This patch contains the fix for CVE-2018-18074 and

a subsequent regression fix combined in one.

---

 sessions.py | 36 +++++++++++++++++++++++++++++-------

 utils.py    |  1 +

 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/sessions.py b/sessions.py

index 6570e73..4038047 100644

--- a/sessions.py

+++ b/sessions.py

@@ -29,7 +29,7 @@ from .adapters import HTTPAdapter

 from .utils import (

     requote_uri, get_environ_proxies, get_netrc_auth, should_bypass_proxies,

-    get_auth_from_url, rewind_body

+    get_auth_from_url, rewind_body, DEFAULT_PORTS

 )

 from .status_codes import codes

@@ -116,6 +116,32 @@ class SessionRedirectMixin(object):

             return to_native_string(location, 'utf8')

         return None

+

+    def should_strip_auth(self, old_url, new_url):

+        """Decide whether Authorization header should be removed when redirecting"""

+        old_parsed = urlparse(old_url)

+        new_parsed = urlparse(new_url)

+        if old_parsed.hostname != new_parsed.hostname:

+            return True

+        # Special case: allow http -> https redirect when using the standard

+        # ports. This isn't specified by RFC 7235, but is kept to avoid

+        # breaking backwards compatibility with older versions of requests

+        # that allowed any redirects on the same host.

+        if (old_parsed.scheme == 'http' and old_parsed.port in (80, None)

+                and new_parsed.scheme == 'https' and new_parsed.port in (443, None)):

+            return False

+

+        # Handle default port usage corresponding to scheme.

+        changed_port = old_parsed.port != new_parsed.port

+        changed_scheme = old_parsed.scheme != new_parsed.scheme

+        default_port = (DEFAULT_PORTS.get(old_parsed.scheme, None), None)

+        if (not changed_scheme and old_parsed.port in default_port

+                and new_parsed.port in default_port):

+            return False

+

+        # Standard case: root URI must match

+        return changed_port or changed_scheme

+

     def resolve_redirects(self, resp, req, stream=False, timeout=None,

                           verify=True, cert=None, proxies=None, yield_requests=False, **adapter_kwargs):

         """Receives a Response. Returns a generator of Responses or Requests."""

@@ -232,14 +258,10 @@ class SessionRedirectMixin(object):

         headers = prepared_request.headers

         url = prepared_request.url

-        if 'Authorization' in headers:

+        if 'Authorization' in headers and self.should_strip_auth(response.request.url, url):

             # If we get redirected to a new host, we should strip out any

             # authentication headers.

-            original_parsed = urlparse(response.request.url)

-            redirect_parsed = urlparse(url)

-

-            if (original_parsed.hostname != redirect_parsed.hostname):

-                del headers['Authorization']

+            del headers['Authorization']

         # .netrc might have more auth for us on our new host.

         new_auth = get_netrc_auth(url) if self.trust_env else None

diff --git a/utils.py b/utils.py

index 5c47de9..5695ab0 100644

--- a/utils.py

+++ b/utils.py

@@ -38,6 +38,7 @@ NETRC_FILES = ('.netrc', '_netrc')

 DEFAULT_CA_BUNDLE_PATH = certs.where()

+DEFAULT_PORTS = {'http': 80, 'https': 443}

 if platform.system() == 'Windows':

     # provide a proxy_bypass version on Windows without DNS lookups

-- 

2.24.1