75 lines
2.5 KiB
Diff
75 lines
2.5 KiB
Diff
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From 90477a3b6e73da69740e00b8161f53fea19b831f Mon Sep 17 00:00:00 2001
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From: Simo Sorce <simo@redhat.com>
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Date: Tue, 5 Mar 2024 16:57:17 -0500
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Subject: [PATCH] Address potential DoS with high compression ratio
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Fixes CVE-2024-28102
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Signed-off-by: Simo Sorce <simo@redhat.com>
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---
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jwcrypto/jwe.py | 7 +++++++
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jwcrypto/tests.py | 26 ++++++++++++++++++++++++++
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2 files changed, 33 insertions(+)
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diff --git a/jwcrypto/jwe.py b/jwcrypto/jwe.py
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index 9412881..5df500b 100644
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--- a/jwcrypto/jwe.py
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+++ b/jwcrypto/jwe.py
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@@ -9,5 +10,8 @@
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from jwcrypto.jwa import JWA
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+# Limit the amount of data we are willing to decompress by default.
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+default_max_compressed_size = 256 * 1024
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+
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# RFC 7516 - 4.1
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# name: (description, supported?)
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@@ -374,6 +374,10 @@ def _decrypt(self, key, ppe):
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compress = jh.get('zip', None)
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if compress == 'DEF':
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+ if len(data) > default_max_compressed_size:
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+ raise InvalidJWEData(
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+ 'Compressed data exceeds maximum allowed'
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+ 'size' + f' ({default_max_compressed_size})')
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self.plaintext = zlib.decompress(data, -zlib.MAX_WBITS)
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elif compress is None:
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self.plaintext = data
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diff --git a/jwcrypto/tests.py b/jwcrypto/tests.py
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index bb2ff10..59049f8 100644
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--- a/jwcrypto/tests.py
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+++ b/jwcrypto/tests.py
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@@ -1196,6 +1196,32 @@ def test_pbes2_hs256_aeskw_custom_params(self):
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check.deserialize(enc, key)
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self.assertEqual(b'plain', check.payload)
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+ def test_jwe_decompression_max(self):
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+ key = jwk.JWK(kty='oct', k=base64url_encode(b'A' * (128 // 8)))
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+ payload = '{"u": "' + "u" * 400000000 + '", "uu":"' \
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+ + "u" * 400000000 + '"}'
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+ protected_header = {
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+ "alg": "A128KW",
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+ "enc": "A128GCM",
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+ "typ": "JWE",
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+ "zip": "DEF",
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+ }
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+ enc = jwe.JWE(payload.encode('utf-8'),
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+ recipient=key,
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+ protected=protected_header).serialize(compact=True)
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+ with self.assertRaises(jwe.InvalidJWEData):
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+ check = jwe.JWE()
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+ check.deserialize(enc)
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+ check.decrypt(key)
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+
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+ defmax = jwe.default_max_compressed_size
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+ jwe.default_max_compressed_size = 1000000000
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+ # ensure we can eraise the limit and decrypt
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+ check = jwe.JWE()
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+ check.deserialize(enc)
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+ check.decrypt(key)
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+ jwe.default_max_compressed_size = defmax
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+
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class JWATests(unittest.TestCase):
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def test_jwa_create(self):
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