New osrandom_engine in C (#3229)

* New osrandom_engine in C Inspired by Python/random.c and the old implementation. Signed-off-by: Christian Heimes <[email protected]> * osrandom_engine * Fix naming bug caused by search 'n replace mistake * Make it easier to override osrandom auto-detection * Add engine ctrl and backend API to get implementation from ENGINE Signed-off-by: Christian Heimes <[email protected]> * Better test coverage, documentation, LICENSE Signed-off-by: Christian Heimes <[email protected]> * Coverage is hard. Signed-off-by: Christian Heimes <[email protected]> * * enable win32 check * read() returns size_t Signed-off-by: Christian Heimes <[email protected]> * Add macOS to spelling list. Remove dead code from header file. Signed-off-by: Christian Heimes <[email protected]> * remove CCRandomGenerateBytes path and update getentropy to work on macOS This change allows us to test all the engines in our CI: * getentropy (tested by macOS sierra) * getrandom (tested on several linux builders) * /dev/urandom (tested on FreeBSD, OS X 10.11 and below, & older linux) * CryptGenRandom (tested on windows builders) I also fixed bugs preventing compilation in the getentropy code * getentropy() returns int and is restricted to 256 bytes on macOS, too. Signed-off-by: Christian Heimes <[email protected]> * add versionadded * Re-add import of os module * Fixes related to Alex's recent review. Signed-off-by: Christian Heimes <[email protected]> * Add error reporting and fail for EAGAIN Add error reporting strings for various error cases. This gives us much nicer and understandable error messages. SYS_getrandom() EAGAIN is now an error. Cryptography refuses to initialize its osrandom engine when the Kernel's CPRNG hasn't been seeded yet. Signed-off-by: Christian Heimes <[email protected]>
pyca · Dec 9, 2016 · 2e71776 · 2e71776
1 parent 0cf3690
commit 2e71776
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diff --git a/LICENSE b/LICENSE
@@ -2,5 +2,6 @@ This software is made available under the terms of *either* of the licenses
 found in LICENSE.APACHE or LICENSE.BSD. Contributions to cryptography are made
 under the terms of *both* these licenses.
 
-The code used in the OpenSSL locking callback is derived from the same in
-Python itself, and is licensed under the terms of the PSF License Agreement.
+The code used in the OpenSSL locking callback and OS random engine is derived
+from the same in CPython itself, and is licensed under the terms of the PSF
+License Agreement.
diff --git a/docs/hazmat/backends/openssl.rst b/docs/hazmat/backends/openssl.rst
@@ -40,6 +40,12 @@ greater.
         Activates the OS random engine. This will effectively disable OpenSSL's
         default CSPRNG.
 
+    .. method:: osrandom_engine_implementation()
+
+        .. versionadded:: 1.7
+
+        Returns the implementation of OS random engine.
+
     .. method:: activate_builtin_random()
 
         This will activate the default OpenSSL CSPRNG.
@@ -81,6 +87,21 @@ details.
 Linux uses its own PRNG design. ``/dev/urandom`` is a non-blocking source
 seeded from the same pool as ``/dev/random``.
 
++------------------------------------------+------------------------------+
+| Windows                                  | ``CryptGenRandom()``         |
++------------------------------------------+------------------------------+
+| Linux >= 3.4.17 with working             | ``getrandom(GRND_NONBLOCK)`` |
+| ``SYS_getrandom`` syscall                |                              |
++------------------------------------------+------------------------------+
+| OpenBSD >= 5.6                           | ``getentropy()``             |
++------------------------------------------+------------------------------+
+| BSD family (including macOS 10.12+) with | ``getentropy()``             |
+| ``SYS_getentropy`` in ``sys/syscall.h``  |                              |
++------------------------------------------+------------------------------+
+| fallback                                 | ``/dev/urandom`` with        |
+|                                          | cached file descriptor       |
++------------------------------------------+------------------------------+
+
 
 .. _`OpenSSL`: https://www.openssl.org/
 .. _`initializing the RNG`: https://en.wikipedia.org/wiki/OpenSSL#Predictable_private_keys_.28Debian-specific.29

diff --git a/docs/spelling_wordlist.txt b/docs/spelling_wordlist.txt
@@ -33,6 +33,7 @@ Docstrings
 El
 Encodings
 endian
+fallback
 Fernet
 fernet
 FIPS
@@ -53,12 +54,14 @@ Mozilla
 multi
 namespace
 namespaces
+macOS
 naïve
 Nonces
 nonces
 online
 paddings
 Parallelization
+personalization
 pickleable
 plaintext
 pre
@@ -75,6 +78,7 @@ serializer
 Serializers
 SHA
 Solaris
+syscall
 Tanja
 testability
 tunable

diff --git a/src/_cffi_src/build_openssl.py b/src/_cffi_src/build_openssl.py
@@ -68,6 +68,7 @@ def _osx_libraries(build_static):
         "objects",
         "ocsp",
         "opensslv",
+        "osrandom_engine",
         "pem",
         "pkcs12",
         "rand",

diff --git a/src/_cffi_src/openssl/osrandom_engine.py b/src/_cffi_src/openssl/osrandom_engine.py
@@ -0,0 +1,29 @@
+# This file is dual licensed under the terms of the Apache License, Version
+# 2.0, and the BSD License. See the LICENSE file in the root of this repository
+# for complete details.
+
+from __future__ import absolute_import, division, print_function
+
+import os
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+
+with open(os.path.join(HERE, "src/osrandom_engine.h")) as f:
+    INCLUDES = f.read()
+
+TYPES = """
+static const char *const Cryptography_osrandom_engine_name;
+static const char *const Cryptography_osrandom_engine_id;
+"""
+
+FUNCTIONS = """
+int Cryptography_add_osrandom_engine(void);
+"""
+
+MACROS = """
+"""
+
+with open(os.path.join(HERE, "src/osrandom_engine.c")) as f:
+    CUSTOMIZATIONS = f.read()
+
+CONDITIONAL_NAMES = {}