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113 lines
4.6 KiB
113 lines
4.6 KiB
From 4f0c74f6aab47c599d33d36cd783b5fa330384d9 Mon Sep 17 00:00:00 2001
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From: Bert JW Regeer <bertjw@regeer.org>
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Date: Sat, 12 Mar 2022 18:48:26 -0700
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Subject: [PATCH 5/8] Validate chunk size in Chunked Encoding are HEXDIG
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RFC7230 states that a chunk-size should be 1*HEXDIG, this is now
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validated before passing the resulting string to int() which would also
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parse other formats for hex, such as: `0x01` as `1` and `+0x01` as `1`.
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This would lead to a potential for a frontend proxy server and waitress
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to disagree on where a chunk started and ended, thereby potentially
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leading to request smuggling.
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With the increased validation if the size is not just hex digits,
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Waitress now returns a Bad Request and stops processing the request.
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(cherry picked from commit d9bdfa0cf210f6daf017d7c5a3cc149bdec8a9a7)
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---
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waitress/receiver.py | 19 ++++++++++++++-----
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waitress/tests/test_functional.py | 22 ++++++++++++++++++++++
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waitress/tests/test_receiver.py | 12 ++++++++++++
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3 files changed, 48 insertions(+), 5 deletions(-)
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diff --git a/waitress/receiver.py b/waitress/receiver.py
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index 106dbc7..9e4bffe 100644
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--- a/waitress/receiver.py
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+++ b/waitress/receiver.py
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@@ -150,12 +150,21 @@ class ChunkedReceiver(object):
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self.all_chunks_received = True
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break
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+
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line = line[:semi]
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- try:
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- sz = int(line.strip(), 16) # hexadecimal
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- except ValueError: # garbage in input
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- self.error = BadRequest("garbage in chunked encoding input")
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- sz = 0
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+
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+ # Remove any whitespace
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+ line = line.strip()
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+
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+ if not ONLY_HEXDIG_RE.match(line):
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+ self.error = BadRequest("Invalid chunk size")
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+ self.all_chunks_received = True
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+
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+ break
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+
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+ # Can not fail due to matching against the regular
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+ # expression above
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+ sz = int(line.strip(), 16) # hexadecimal
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if sz > 0:
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# Start a new chunk.
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diff --git a/waitress/tests/test_functional.py b/waitress/tests/test_functional.py
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index b1aac96..a7421c6 100644
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--- a/waitress/tests/test_functional.py
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+++ b/waitress/tests/test_functional.py
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@@ -343,6 +343,28 @@ class EchoTests(object):
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self.send_check_error(to_send)
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self.assertRaises(ConnectionClosed, read_http, fp)
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+ def test_broken_chunked_encoding_invalid_hex(self):
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+ control_line = b"0x20\r\n" # 20 hex = 32 dec
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+ s = b"This string has 32 characters.\r\n"
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+ to_send = b"GET / HTTP/1.1\r\nTransfer-Encoding: chunked\r\n\r\n"
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+ to_send += control_line + s + b"\r\n"
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+ self.connect()
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+ self.sock.send(to_send)
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+ fp = self.sock.makefile("rb", 0)
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+ line, headers, response_body = read_http(fp)
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+ self.assertline(line, "400", "Bad Request", "HTTP/1.1")
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+ cl = int(headers["content-length"])
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+ self.assertEqual(cl, len(response_body))
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+ self.assertIn(b"Invalid chunk size", response_body)
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+ self.assertEqual(
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+ sorted(headers.keys()),
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+ ["connection", "content-length", "content-type", "date", "server"],
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+ )
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+ self.assertEqual(headers["content-type"], "text/plain")
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+ # connection has been closed
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+ self.send_check_error(to_send)
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+ self.assertRaises(ConnectionClosed, read_http, fp)
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+
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def test_broken_chunked_encoding_invalid_extension(self):
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control_line = b"20;invalid=\r\n" # 20 hex = 32 dec
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s = b"This string has 32 characters.\r\n"
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diff --git a/waitress/tests/test_receiver.py b/waitress/tests/test_receiver.py
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index e5d31a3..b539264 100644
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--- a/waitress/tests/test_receiver.py
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+++ b/waitress/tests/test_receiver.py
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@@ -256,6 +256,18 @@ class TestChunkedReceiverParametrized:
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assert result == len(data)
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assert inst.error == None
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+ def test_received_invalid_size(self, invalid_size):
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+ from waitress.utilities import BadRequest
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+
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+ for invalid_size in [b"0x04", b"+0x04", b"x04", b"+04"]:
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+ buf = DummyBuffer()
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+ inst = self._makeOne(buf)
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+ data = invalid_size + b"\r\ntest\r\n"
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+ result = inst.received(data)
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+ assert result == len(data)
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+ assert inst.error.__class__ == BadRequest
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+ assert inst.error.body == "Invalid chunk size"
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+
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class DummyBuffer(object):
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def __init__(self, data=None):
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--
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2.45.2
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