From ea33946e3adef1baa9e5e17c584f7f63ec864f57 Mon Sep 17 00:00:00 2001
From: AMIR <31338382+amiremohamadi@users.noreply.github.com>
Date: Sun, 19 Jul 2020 00:46:10 +0430
Subject: [PATCH] bpo-39603: Prevent header injection in http methods
(GH-18485)
reject control chars in http method in http.client.putrequest to prevent http header injection
(cherry picked from commit 8ca8a2e8fb068863c1138f07e3098478ef8be12e)
Co-authored-by: AMIR <31338382+amiremohamadi@users.noreply.github.com>
---
Lib/http/client.py | 15 +++++++++++++
Lib/test/test_httplib.py | 22 +++++++++++++++++++
.../2020-02-12-14-17-39.bpo-39603.Gt3RSg.rst | 2 ++
3 files changed, 39 insertions(+)
create mode 100644 Misc/NEWS.d/next/Security/2020-02-12-14-17-39.bpo-39603.Gt3RSg.rst
diff --git a/Lib/http/client.py b/Lib/http/client.py
index c0ac7db6f40a08..53581eca20587d 100644
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -151,6 +151,10 @@
# _is_allowed_url_pchars_re = re.compile(r"^[/!$&'()*+,;=:@%a-zA-Z0-9._~-]+$")
# We are more lenient for assumed real world compatibility purposes.
+# These characters are not allowed within HTTP method names
+# to prevent http header injection.
+_contains_disallowed_method_pchar_re = re.compile('[\x00-\x1f]')
+
# We always set the Content-Length header for these methods because some
# servers will otherwise respond with a 411
_METHODS_EXPECTING_BODY = {'PATCH', 'POST', 'PUT'}
@@ -1119,6 +1123,8 @@ def putrequest(self, method, url, skip_host=False,
else:
raise CannotSendRequest(self.__state)
+ self._validate_method(method)
+
# Save the method for use later in the response phase
self._method = method
@@ -1209,6 +1215,15 @@ def _encode_request(self, request):
# ASCII also helps prevent CVE-2019-9740.
return request.encode('ascii')
+ def _validate_method(self, method):
+ """Validate a method name for putrequest."""
+ # prevent http header injection
+ match = _contains_disallowed_method_pchar_re.search(method)
+ if match:
+ raise ValueError(
+ f"method can't contain control characters. {method!r} "
+ f"(found at least {match.group()!r})")
+
def _validate_path(self, url):
"""Validate a url for putrequest."""
# Prevent CVE-2019-9740.
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index fcd9231666edef..03e049b13fd211 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -359,6 +359,28 @@ def test_headers_debuglevel(self):
self.assertEqual(lines[2], "header: Second: val")
+class HttpMethodTests(TestCase):
+ def test_invalid_method_names(self):
+ methods = (
+ 'GET\r',
+ 'POST\n',
+ 'PUT\n\r',
+ 'POST\nValue',
+ 'POST\nHOST:abc',
+ 'GET\nrHost:abc\n',
+ 'POST\rRemainder:\r',
+ 'GET\rHOST:\n',
+ '\nPUT'
+ )
+
+ for method in methods:
+ with self.assertRaisesRegex(
+ ValueError, "method can't contain control characters"):
+ conn = client.HTTPConnection('example.com')
+ conn.sock = FakeSocket(None)
+ conn.request(method=method, url="/")
+
+
class TransferEncodingTest(TestCase):
expected_body = b"It's just a flesh wound"
diff --git a/Misc/NEWS.d/next/Security/2020-02-12-14-17-39.bpo-39603.Gt3RSg.rst b/Misc/NEWS.d/next/Security/2020-02-12-14-17-39.bpo-39603.Gt3RSg.rst
new file mode 100644
index 00000000000000..990affc3edd9d8
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2020-02-12-14-17-39.bpo-39603.Gt3RSg.rst
@@ -0,0 +1,2 @@
+Prevent http header injection by rejecting control characters in
+http.client.putrequest(...).
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