[PATCH v4 7/8] Makefile: allow specifying a SHA-1 for non-cryptographic uses
- From
Taylor Blau <me@ttaylorr.com>
- Date
- Sep 24, 2024, 17:32 UTC
- Message-ID
- <af8fd9aa4ede1fb37d4990dd52c5de0f9b9fa681.1727199118.git.me@ttaylorr.com>
- In-Reply-To
- <cover.1727199118.git.me@ttaylorr.com>
Introduce _UNSAFE variants of the OPENSSL_SHA1, BLK_SHA1, and APPLE_COMMON_CRYPTO_SHA1 compile-time knobs which indicate which SHA-1 implementation is to be used for non-cryptographic uses.
There are a couple of small implementation notes worth mentioning:
- There is no way to select the collision detecting SHA-1 as the
"fast" fallback, since the fast fallback is only for
non-cryptographic uses, and is meant to be faster than our
collision-detecting implementation. - There are no similar knobs for SHA-256, since no collision attacks
are presently known and thus no collision-detecting implementations
actually exist.Signed-off-by: Taylor Blau <me@ttaylorr.com> --- Makefile | 25 +++++++++++++++++++++++++ hash.h | 30 ++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+)
diff --git a/Makefile b/Makefile index 9cf2be070fa..fb84a87592d 100644 --- a/Makefile +++ b/Makefile @@ -521,6 +521,10 @@ include shared.mak # Define APPLE_COMMON_CRYPTO_SHA1 to use Apple's CommonCrypto for # SHA-1. # +# Define the same Makefile knobs as above, but suffixed with _UNSAFE to +# use the corresponding implementations for unsafe SHA-1 hashing for +# non-cryptographic purposes. +# # If don't enable any of the *_SHA1 settings in this section, Git will # default to its built-in sha1collisiondetection library, which is a # collision-detecting sha1 This is slower, but may detect attempted @@ -1996,6 +2000,27 @@ endif endif endif +ifdef OPENSSL_SHA1_UNSAFE +ifndef OPENSSL_SHA1 + EXTLIBS += $(LIB_4_CRYPTO) + BASIC_CFLAGS += -DSHA1_OPENSSL_UNSAFE +endif +else +ifdef BLK_SHA1_UNSAFE +ifndef BLK_SHA1 + LIB_OBJS += block-sha1/sha1.o + BASIC_CFLAGS += -DSHA1_BLK_UNSAFE +endif +else +ifdef APPLE_COMMON_CRYPTO_SHA1_UNSAFE +ifndef APPLE_COMMON_CRYPTO_SHA1 + COMPAT_CFLAGS += -DCOMMON_DIGEST_FOR_OPENSSL + BASIC_CFLAGS += -DSHA1_APPLE_UNSAFE +endif +endif +endif +endif + ifdef OPENSSL_SHA256 EXTLIBS += $(LIB_4_CRYPTO) BASIC_CFLAGS += -DSHA256_OPENSSL diff --git a/hash.h b/hash.h index 96458b129f9..f97f858307b 100644 --- a/hash.h +++ b/hash.h @@ -15,6 +15,36 @@ #include "block-sha1/sha1.h" #endif +#if defined(SHA1_APPLE_UNSAFE) +# include <CommonCrypto/CommonDigest.h> +# define platform_SHA_CTX_unsafe CC_SHA1_CTX +# define platform_SHA1_Init_unsafe CC_SHA1_Init +# define platform_SHA1_Update_unsafe CC_SHA1_Update +# define platform_SHA1_Final_unsafe CC_SHA1_Final +#elif defined(SHA1_OPENSSL_UNSAFE) +# include <openssl/sha.h> +# if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3 +# define SHA1_NEEDS_CLONE_HELPER_UNSAFE +# include "sha1/openssl.h" +# define platform_SHA_CTX_unsafe openssl_SHA1_CTX +# define platform_SHA1_Init_unsafe openssl_SHA1_Init +# define platform_SHA1_Clone_unsafe openssl_SHA1_Clone +# define platform_SHA1_Update_unsafe openssl_SHA1_Update +# define platform_SHA1_Final_unsafe openssl_SHA1_Final +# else +# define platform_SHA_CTX_unsafe SHA_CTX +# define platform_SHA1_Init_unsafe SHA1_Init +# define platform_SHA1_Update_unsafe SHA1_Update +# define platform_SHA1_Final_unsafe SHA1_Final +# endif +#elif defined(SHA1_BLK_UNSAFE) +# include "block-sha1/sha1.h" +# define platform_SHA_CTX_unsafe blk_SHA_CTX +# define platform_SHA1_Init_unsafe blk_SHA1_Init +# define platform_SHA1_Update_unsafe blk_SHA1_Update +# define platform_SHA1_Final_unsafe blk_SHA1_Final +#endif + #if defined(SHA256_NETTLE) #include "sha256/nettle.h" #elif defined(SHA256_GCRYPT)
-- 2.46.2.636.g4b83dd05e9f