Accepting request 352108 from devel:languages:python
1 OBS-URL: https://build.opensuse.org/request/show/352108 OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/python-rsa?expand=0&rev=12
This commit is contained in:
Dominique Leuenberger
Git OBS Bridge
commit
60e9ccb2a5
103
cve_2016-1494.diff
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103
cve_2016-1494.diff
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@ -0,0 +1,103 @@
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# HG changeset patch
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# User Filippo Valsorda <hi@filippo.io>
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# Date 1450226563 0
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# Node ID 0cbcc529926afd61c6df4f50cfc29971beafd2c2
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# Parent 2baab06c8b867b01ec82b02118d4872a931a0437
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Fix BB'06 attack in verify() by switching from parsing to comparison
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diff --git a/rsa/pkcs1.py b/rsa/pkcs1.py
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--- a/rsa/pkcs1.py
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+++ b/rsa/pkcs1.py
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@@ -22,10 +22,10 @@
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At least 8 bytes of random padding is used when encrypting a message. This makes
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these methods much more secure than the ones in the ``rsa`` module.
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-WARNING: this module leaks information when decryption or verification fails.
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-The exceptions that are raised contain the Python traceback information, which
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-can be used to deduce where in the process the failure occurred. DO NOT PASS
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-SUCH INFORMATION to your users.
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+WARNING: this module leaks information when decryption fails. The exceptions
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+that are raised contain the Python traceback information, which can be used to
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+deduce where in the process the failure occurred. DO NOT PASS SUCH INFORMATION
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+to your users.
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'''
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import hashlib
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@@ -288,37 +288,23 @@
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:param pub_key: the :py:class:`rsa.PublicKey` of the person signing the message.
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:raise VerificationError: when the signature doesn't match the message.
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- .. warning::
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-
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- Never display the stack trace of a
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- :py:class:`rsa.pkcs1.VerificationError` exception. It shows where in
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- the code the exception occurred, and thus leaks information about the
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- key. It's only a tiny bit of information, but every bit makes cracking
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- the keys easier.
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-
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'''
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- blocksize = common.byte_size(pub_key.n)
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+ keylength = common.byte_size(pub_key.n)
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encrypted = transform.bytes2int(signature)
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decrypted = core.decrypt_int(encrypted, pub_key.e, pub_key.n)
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- clearsig = transform.int2bytes(decrypted, blocksize)
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-
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- # If we can't find the signature marker, verification failed.
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- if clearsig[0:2] != b('\x00\x01'):
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- raise VerificationError('Verification failed')
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+ clearsig = transform.int2bytes(decrypted, keylength)
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- # Find the 00 separator between the padding and the payload
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- try:
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- sep_idx = clearsig.index(b('\x00'), 2)
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- except ValueError:
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- raise VerificationError('Verification failed')
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-
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- # Get the hash and the hash method
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- (method_name, signature_hash) = _find_method_hash(clearsig[sep_idx+1:])
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+ # Get the hash method
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+ method_name = _find_method_hash(clearsig)
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message_hash = _hash(message, method_name)
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- # Compare the real hash to the hash in the signature
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- if message_hash != signature_hash:
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+ # Reconstruct the expected padded hash
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+ cleartext = HASH_ASN1[method_name] + message_hash
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+ expected = _pad_for_signing(cleartext, keylength)
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+
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+ # Compare with the signed one
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+ if expected != clearsig:
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raise VerificationError('Verification failed')
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return True
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@@ -351,24 +337,20 @@
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return hasher.digest()
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-def _find_method_hash(method_hash):
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- '''Finds the hash method and the hash itself.
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+def _find_method_hash(clearsig):
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+ '''Finds the hash method.
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- :param method_hash: ASN1 code for the hash method concatenated with the
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- hash itself.
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+ :param clearsig: full padded ASN1 and hash.
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- :return: tuple (method, hash) where ``method`` is the used hash method, and
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- ``hash`` is the hash itself.
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+ :return: the used hash method.
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:raise VerificationFailed: when the hash method cannot be found
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'''
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for (hashname, asn1code) in HASH_ASN1.items():
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- if not method_hash.startswith(asn1code):
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- continue
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-
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- return (hashname, method_hash[len(asn1code):])
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+ if asn1code in clearsig:
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+ return hashname
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raise VerificationError('Verification failed')
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@ -1,3 +1,9 @@
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-------------------------------------------------------------------
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Tue Jan 5 18:39:56 UTC 2016 - rjschwei@suse.com
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- Fix CVE 2016-1494 (bsc#960680)
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- Add patch cve_2016-1494.diff
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-------------------------------------------------------------------
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Tue Dec 1 15:02:09 UTC 2015 - rjschwei@suse.com
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@ -1,7 +1,7 @@
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#
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# spec file for package python-rsa
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#
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# Copyright (c) 2015 SUSE LINUX GmbH, Nuernberg, Germany.
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# Copyright (c) 2016 SUSE LINUX GmbH, Nuernberg, Germany.
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#
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# All modifications and additions to the file contributed by third parties
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# remain the property of their copyright owners, unless otherwise agreed
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@ -24,6 +24,7 @@ Summary: Pure-Python RSA Implementation
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License: Apache-2.0
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Group: Development/Languages/Python
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Source: http://pypi.python.org/packages/source/r/rsa/rsa-%{version}.tar.gz
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Patch0: cve_2016-1494.diff
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BuildRoot: %{_tmppath}/%{name}-%{version}-build
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BuildRequires: python-devel
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BuildRequires: python-pyasn1
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@ -55,6 +56,7 @@ sed -i "s/pyrsa-sign/pyrsa-sign-%{py_ver}/" setup.py
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sed -i "s/pyrsa-verify/pyrsa-verify-%{py_ver}/" setup.py
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sed -i "s/pyrsa-encrypt-bigfile =/pyrsa-encrypt-bigfile-%{py_ver} =/" setup.py
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sed -i "s/pyrsa-decrypt-bigfile =/pyrsa-decrypt-bigfile-%{py_ver} =/" setup.py
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%patch0 -p1
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%build
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python setup.py build
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