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Optionally use OpenSSL or LibreSSL instead of bundled crypto-algorithms

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crypto-algorithms "have no resistence to side-channel attacks and should not
be used in contexts that need cryptographically secure implementations" (see
lib/crypto-algorithms/README.md), so using OpenSSL or LibreSSL is preferable.

This does solve https://github.com/matrix-org/olm/issues/3 for some platforms,
without breaking other platforms without these libraries (like web).

Signed-off-by: Lukas Lihotzki <lukas@lihotzki.de>
This commit is contained in:
Lukas Lihotzki 2021-04-26 12:23:08 +02:00 committed by Hubert Chathi
parent 18ad6cb067
commit 386431d831
3 changed files with 328 additions and 2 deletions
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18
CMakeLists.txt
View file

@ -4,6 +4,8 @@ project(olm VERSION 3.2.2 LANGUAGES CXX C)
option(OLM_TESTS "Build tests" ON)
option(BUILD_SHARED_LIBS "Build as a shared library" ON)
option(OLM_USE_OPENSSL "Use OpenSSL instead of bundled crypto-algorithms" OFF)
option(OLM_USE_LIBRESSL "Use LibreSSL instead of bundled crypto-algorithms" OFF)
add_definitions(-DOLMLIB_VERSION_MAJOR=${PROJECT_VERSION_MAJOR})
add_definitions(-DOLMLIB_VERSION_MINOR=${PROJECT_VERSION_MINOR})
@ -43,11 +45,23 @@ add_library(olm
src/outbound_group_session.c
src/pickle_encoding.c
lib/crypto-algorithms/aes.c
lib/crypto-algorithms/sha256.c
lib/curve25519-donna/curve25519-donna.c)
add_library(Olm::Olm ALIAS olm)
if(OLM_USE_OPENSSL)
find_package(OpenSSL REQUIRED)
target_link_libraries(olm OpenSSL::Crypto)
target_compile_definitions(olm PRIVATE OLM_USE_OPENSSL)
elseif(OLM_USE_LIBRESSL)
find_package(LibreSSL REQUIRED)
target_link_libraries(olm LibreSSL::Crypto)
target_compile_definitions(olm PRIVATE OLM_USE_LIBRESSL)
else()
target_sources(olm PRIVATE
lib/crypto-algorithms/aes.c
lib/crypto-algorithms/sha256.c)
endif()
target_include_directories(olm
PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>

227
cmake/FindLibreSSL.cmake Normal file
View file

@ -0,0 +1,227 @@
#[=======================================================================[
Copyright (c) 2019 John Norrbin <jlnorrbin@johnex.se>
Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
FindLibreSSL
------------
Find the LibreSSL encryption library.
Optional Components
^^^^^^^^^^^^^^^^^^^
This module supports two optional components: SSL and TLS. Both
components have associated imported targets, as described below.
Imported Targets
^^^^^^^^^^^^^^^^
This module defines the following imported targets:
LibreSSL::Crypto
The LibreSSL crypto library, if found.
LibreSSL::SSL
The LibreSSL ssl library, if found. Requires and includes LibreSSL::Crypto automatically.
LibreSSL::TLS
The LibreSSL tls library, if found. Requires and includes LibreSSL::SSL and LibreSSL::Crypto automatically.
Result Variables
^^^^^^^^^^^^^^^^
This module will set the following variables in your project:
LIBRESSL_FOUND
System has the LibreSSL library. If no components are requested it only requires the crypto library.
LIBRESSL_INCLUDE_DIR
The LibreSSL include directory.
LIBRESSL_CRYPTO_LIBRARY
The LibreSSL crypto library.
LIBRESSL_SSL_LIBRARY
The LibreSSL SSL library.
LIBRESSL_TLS_LIBRARY
The LibreSSL TLS library.
LIBRESSL_LIBRARIES
All LibreSSL libraries.
LIBRESSL_VERSION
This is set to $major.$minor.$revision (e.g. 2.6.8).
Hints
^^^^^
Set LIBRESSL_ROOT_DIR to the root directory of an LibreSSL installation.
]=======================================================================]
INCLUDE(FindPackageHandleStandardArgs)
# Set Hints
set(_LIBRESSL_ROOT_HINTS
${LIBRESSL_ROOT_DIR}
ENV LIBRESSL_ROOT_DIR
)
# Set Paths
if (WIN32)
file(TO_CMAKE_PATH "$ENV{PROGRAMFILES}" _programfiles)
set(_LIBRESSL_ROOT_PATHS
"${_programfiles}/LibreSSL"
)
unset(_programfiles)
else()
set(_LIBRESSL_ROOT_PATHS
"/usr/local/"
)
endif()
# Combine
set(_LIBRESSL_ROOT_HINTS_AND_PATHS
HINTS ${_LIBRESSL_ROOT_HINTS}
PATHS ${_LIBRESSL_ROOT_PATHS}
)
# Find Include Path
find_path(LIBRESSL_INCLUDE_DIR
NAMES
tls.h
${_LIBRESSL_ROOT_HINTS_AND_PATHS}
PATH_SUFFIXES
include
)
# Find Crypto Library
find_library(LIBRESSL_CRYPTO_LIBRARY
NAMES
libcrypto
crypto
NAMES_PER_DIR
${_LIBRESSL_ROOT_HINTS_AND_PATHS}
PATH_SUFFIXES
lib
)
# Find SSL Library
find_library(LIBRESSL_SSL_LIBRARY
NAMES
libssl
ssl
NAMES_PER_DIR
${_LIBRESSL_ROOT_HINTS_AND_PATHS}
PATH_SUFFIXES
lib
)
# Find TLS Library
find_library(LIBRESSL_TLS_LIBRARY
NAMES
libtls
tls
NAMES_PER_DIR
${_LIBRESSL_ROOT_HINTS_AND_PATHS}
PATH_SUFFIXES
lib
)
# Set Libraries
set(LIBRESSL_LIBRARIES ${LIBRESSL_CRYPTO_LIBRARY} ${LIBRESSL_SSL_LIBRARY} ${LIBRESSL_TLS_LIBRARY})
# Mark Variables As Advanced
mark_as_advanced(LIBRESSL_INCLUDE_DIR LIBRESSL_LIBRARIES LIBRESSL_CRYPTO_LIBRARY LIBRESSL_SSL_LIBRARY LIBRESSL_TLS_LIBRARY)
# Find Version File
if(LIBRESSL_INCLUDE_DIR AND EXISTS "${LIBRESSL_INCLUDE_DIR}/openssl/opensslv.h")
# Get Version From File
file(STRINGS "${LIBRESSL_INCLUDE_DIR}/openssl/opensslv.h" OPENSSLV.H REGEX "#define LIBRESSL_VERSION_TEXT[ ]+\".*\"")
# Match Version String
string(REGEX REPLACE ".*\".*([0-9]+)\\.([0-9]+)\\.([0-9]+)\"" "\\1;\\2;\\3" LIBRESSL_VERSION_LIST "${OPENSSLV.H}")
# Split Parts
list(GET LIBRESSL_VERSION_LIST 0 LIBRESSL_VERSION_MAJOR)
list(GET LIBRESSL_VERSION_LIST 1 LIBRESSL_VERSION_MINOR)
list(GET LIBRESSL_VERSION_LIST 2 LIBRESSL_VERSION_REVISION)
# Set Version String
set(LIBRESSL_VERSION "${LIBRESSL_VERSION_MAJOR}.${LIBRESSL_VERSION_MINOR}.${LIBRESSL_VERSION_REVISION}")
endif()
# Set Find Package Arguments
find_package_handle_standard_args(LibreSSL
REQUIRED_VARS
LIBRESSL_CRYPTO_LIBRARY
LIBRESSL_INCLUDE_DIR
VERSION_VAR
LIBRESSL_VERSION
HANDLE_COMPONENTS
FAIL_MESSAGE
"Could NOT find LibreSSL, try setting the path to LibreSSL using the LIBRESSL_ROOT_DIR environment variable"
)
# LibreSSL Found
if(LIBRESSL_FOUND)
# Set LibreSSL::Crypto
if(NOT TARGET LibreSSL::Crypto AND EXISTS "${LIBRESSL_CRYPTO_LIBRARY}")
# Add Library
add_library(LibreSSL::Crypto UNKNOWN IMPORTED)
# Set Properties
set_target_properties(
LibreSSL::Crypto
PROPERTIES
INTERFACE_INCLUDE_DIRECTORIES "${LIBRESSL_INCLUDE_DIR}"
IMPORTED_LINK_INTERFACE_LANGUAGES "C"
IMPORTED_LOCATION "${LIBRESSL_CRYPTO_LIBRARY}"
)
endif() # LibreSSL::Crypto
# Set LibreSSL::SSL
if(NOT TARGET LibreSSL::SSL AND EXISTS "${LIBRESSL_SSL_LIBRARY}")
# Add Library
add_library(LibreSSL::SSL UNKNOWN IMPORTED)
# Set Properties
set_target_properties(
LibreSSL::SSL
PROPERTIES
INTERFACE_INCLUDE_DIRECTORIES "${LIBRESSL_INCLUDE_DIR}"
IMPORTED_LINK_INTERFACE_LANGUAGES "C"
IMPORTED_LOCATION "${LIBRESSL_SSL_LIBRARY}"
INTERFACE_LINK_LIBRARIES LibreSSL::Crypto
)
endif() # LibreSSL::SSL
# Set LibreSSL::TLS
if(NOT TARGET LibreSSL::TLS AND EXISTS "${LIBRESSL_TLS_LIBRARY}")
add_library(LibreSSL::TLS UNKNOWN IMPORTED)
set_target_properties(
LibreSSL::TLS
PROPERTIES
INTERFACE_INCLUDE_DIRECTORIES "${LIBRESSL_INCLUDE_DIR}"
IMPORTED_LINK_INTERFACE_LANGUAGES "C"
IMPORTED_LOCATION "${LIBRESSL_TLS_LIBRARY}"
INTERFACE_LINK_LIBRARIES LibreSSL::SSL
)
endif() # LibreSSL::TLS
endif(LIBRESSL_FOUND)

85
src/crypto.cpp
View file

@ -17,12 +17,23 @@
#include <cstring>
#if defined(OLM_USE_OPENSSL) || defined(OLM_USE_LIBRESSL)
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#ifdef OLM_USE_OPENSSL
#include <openssl/kdf.h>
#else
#include <openssl/hkdf.h>
#endif
#else
extern "C" {
#include "crypto-algorithms/aes.h"
#include "crypto-algorithms/sha256.h"
}
#endif
#include "ed25519/src/ed25519.h"
#include "curve25519-donna.h"
@ -37,6 +48,8 @@ static const std::size_t SHA256_BLOCK_LENGTH = 64;
static const std::uint8_t HKDF_DEFAULT_SALT[32] = {};
#if !defined(OLM_USE_OPENSSL) && !defined(OLM_USE_LIBRESSL)
template<std::size_t block_size>
inline static void xor_block(
std::uint8_t * block,
@ -98,6 +111,20 @@ inline static void hmac_sha256_final(
olm::unset(o_pad);
}
#else
template <typename T>
static T checked(T val) {
if (!val) {
abort();
}
return val;
}
#endif
} // namespace
void _olm_crypto_curve25519_generate_key(
@ -176,6 +203,14 @@ void _olm_crypto_aes_encrypt_cbc(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
#if defined(OLM_USE_OPENSSL) || defined(OLM_USE_LIBRESSL)
EVP_CIPHER_CTX* ctx = checked(EVP_CIPHER_CTX_new());
checked(EVP_EncryptInit_ex(ctx, EVP_aes_256_cbc(), nullptr, key->key, iv->iv));
int output_length[2];
checked(EVP_EncryptUpdate(ctx, output, &output_length[0], input, input_length));
checked(EVP_EncryptFinal_ex(ctx, output + output_length[0], &output_length[1]));
EVP_CIPHER_CTX_free(ctx);
#else
std::uint32_t key_schedule[AES_KEY_SCHEDULE_LENGTH];
::aes_key_setup(key->key, key_schedule, AES_KEY_BITS);
std::uint8_t input_block[AES_BLOCK_LENGTH];
@ -198,6 +233,7 @@ void _olm_crypto_aes_encrypt_cbc(
::aes_encrypt(input_block, output, key_schedule, AES_KEY_BITS);
olm::unset(key_schedule);
olm::unset(input_block);
#endif
}
@ -207,6 +243,15 @@ std::size_t _olm_crypto_aes_decrypt_cbc(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
#if defined(OLM_USE_OPENSSL) || defined(OLM_USE_LIBRESSL)
EVP_CIPHER_CTX* ctx = checked(EVP_CIPHER_CTX_new());
checked(EVP_DecryptInit_ex(ctx, EVP_aes_256_cbc(), nullptr, key->key, iv->iv));
int output_length[2];
checked(EVP_DecryptUpdate(ctx, output, &output_length[0], input, input_length));
checked(EVP_DecryptFinal_ex(ctx, output + output_length[0], &output_length[1]));
EVP_CIPHER_CTX_free(ctx);
return output_length[0] + output_length[1];
#else
std::uint32_t key_schedule[AES_KEY_SCHEDULE_LENGTH];
::aes_key_setup(key->key, key_schedule, AES_KEY_BITS);
std::uint8_t block1[AES_BLOCK_LENGTH];
@ -223,6 +268,7 @@ std::size_t _olm_crypto_aes_decrypt_cbc(
olm::unset(block2);
std::size_t padding = output[input_length - 1];
return (padding > input_length) ? std::size_t(-1) : (input_length - padding);
#endif
}
@ -230,11 +276,15 @@ void _olm_crypto_sha256(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
#if defined(OLM_USE_OPENSSL) || defined(OLM_USE_LIBRESSL)
checked(EVP_Digest(input, input_length, output, nullptr, EVP_sha256(), nullptr));
#else
::SHA256_CTX context;
::sha256_init(&context);
::sha256_update(&context, input, input_length);
::sha256_final(&context, output);
olm::unset(context);
#endif
}
@ -243,6 +293,9 @@ void _olm_crypto_hmac_sha256(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
) {
#if defined(OLM_USE_OPENSSL) || defined(OLM_USE_LIBRESSL)
checked(HMAC(EVP_sha256(), key, key_length, input, input_length, output, nullptr));
#else
std::uint8_t hmac_key[SHA256_BLOCK_LENGTH];
::SHA256_CTX context;
hmac_sha256_key(key, key_length, hmac_key);
@ -251,6 +304,7 @@ void _olm_crypto_hmac_sha256(
hmac_sha256_final(&context, hmac_key, output);
olm::unset(hmac_key);
olm::unset(context);
#endif
}
@ -260,6 +314,36 @@ void _olm_crypto_hkdf_sha256(
std::uint8_t const * info, std::size_t info_length,
std::uint8_t * output, std::size_t output_length
) {
#ifdef OLM_USE_OPENSSL
EVP_PKEY_CTX *pctx = checked(EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL));
checked(EVP_PKEY_derive_init(pctx));
checked(EVP_PKEY_CTX_set_hkdf_md(pctx, EVP_sha256()));
if (input_length) {
checked(EVP_PKEY_CTX_set1_hkdf_key(pctx, input, input_length));
} else {
/* OpenSSL HKDF doesn't directly support zero-length keys:
* https://github.com/openssl/openssl/issues/8531
* Do the extract step manually with HMAC and use HKDF only for expand */
uint8_t intermediate[SHA256_OUTPUT_LENGTH];
checked(HMAC(EVP_sha256(), nullptr, 0, salt, salt_length, intermediate, nullptr));
checked(EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY));
checked(EVP_PKEY_CTX_set1_hkdf_key(pctx, intermediate, sizeof(intermediate)));
}
checked(EVP_PKEY_CTX_set1_hkdf_salt(pctx, salt, salt_length));
checked(EVP_PKEY_CTX_add1_hkdf_info(pctx, info, info_length));
checked(EVP_PKEY_derive(pctx, output, &output_length));
EVP_PKEY_CTX_free(pctx);
#elif defined(OLM_USE_LIBRESSL)
if (salt_length == 0) {
/* LibreSSL HKDF rejects nullptr salt, even if salt_length is 0.
* salt needs to be set to something else. */
salt = (const uint8_t*)"";
}
checked(HKDF(output, output_length, EVP_sha256(), input, input_length,
salt, salt_length, info, info_length));
#else
::SHA256_CTX context;
std::uint8_t hmac_key[SHA256_BLOCK_LENGTH];
std::uint8_t step_result[SHA256_OUTPUT_LENGTH];
@ -296,4 +380,5 @@ void _olm_crypto_hkdf_sha256(
olm::unset(context);
olm::unset(hmac_key);
olm::unset(step_result);
#endif
}