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lib/crypto: mips: Disable Octeon SHA code on little-endian kernels

PATCH Applied Eric Biggers 2 participants 3 messages Oct 22 – Oct 24

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Eric Biggers

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#0 lore raw

PATCH 1/1 lib/crypto: mips: Disable Octeon SHA code on little-endian kernels

Kernels built for the MIPS64-based Cavium Octeon SoCs are normally big-endian, but little-endian builds are also supported. Currently, the SHA-1, SHA-256, and SHA-512 code using the Octeon crypto co-processor is enabled in both builds.

This code is untestable without the hardware. However, based on the code itself, it is implausible that it computes hash values correctly in little-endian builds. Such builds write many incorrect values to COP2:

- SHA-1 and SHA-256: The 64-bit integer that contains the last two 32-bit message words of each block is written to COP2 entirely byte-reflected, due to missing endianness conversion in octeon_sha1_start() and octeon_sha256_start() to compensate for using native 64-bit loads from the message bytes. This differs from all the earlier message words which are written correctly.

Furthermore, the state is written to COP2 with each 32-bit word byte-reflected within each 64-bit integer, due to incorrect use of 64-bit endianness conversion in write_octeon_64bit_hash_dword() when the state is kept in memory in native-endian 32-bit words.

- SHA-512: All the 64-bit message words are written to COP2 byte-reflected, due to missing endianness conversion in write_octeon_64bit_block_sha512() and octeon_sha512_start(). The SHA-512 state words seem to be written correctly.

Big-endian kernels aren't affected by these bugs. These bugs also aren't new; this code has been broken on little-endian ever since it and Octeon little-endian support were first added in v4.1.

Commit d2a948d2db68 ("MIPS: Octeon: Make octeon-md5 driver endian-agnostic") made the MD5 code work on little-endian kernels by adding 64-bit endianness conversions to the COP2 macros used by MD5 (some of which are shared by SHA-1 and SHA-256, despite those algorithms keeping the state words in native-endian instead of MD5's little-endian, causing some of the strange behavior described above). However, SHA-1, SHA-256, and SHA-512 were never fixed to work on little-endian kernels.

Therefore, disable the Octeon SHA-1, SHA-256, and SHA-512 code in little-endian kernels. This causes the generic code that actually computes hash values correctly to be used instead.

Fixes 82be2dcfa6a1 ("crypto: octeon - add SHA1 module")
Fixes c3d0def62001 ("crypto: octeon - add SHA256 module")
Fixes fbaa4dfd51a0 ("crypto: octeon - add SHA512 module")
Cc [email protected]
Signed-off-by Eric Biggers <[email protected]>

---

This patch is intended to be taken through libcrypto-fixes.

 lib/crypto/Kconfig | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
lib/crypto/Kconfig +3 -3
index 56f308dd02731..83b4a211c15d6 100644
@@ -237,7 +237,7 @@ config CRYPTO_LIB_SHA1_ARCH
 	depends on CRYPTO_LIB_SHA1 && !UML
 	default y if ARM
 	default y if ARM64
-	default y if MIPS && CPU_CAVIUM_OCTEON
+	default y if MIPS && CPU_CAVIUM_OCTEON && CPU_BIG_ENDIAN
 	default y if PPC
 	default y if S390
 	default y if SPARC64

@@ -255,7 +255,7 @@ config CRYPTO_LIB_SHA256_ARCH
 	depends on CRYPTO_LIB_SHA256 && !UML
 	default y if ARM && !CPU_V7M
 	default y if ARM64
-	default y if MIPS && CPU_CAVIUM_OCTEON
+	default y if MIPS && CPU_CAVIUM_OCTEON && CPU_BIG_ENDIAN
 	default y if PPC && SPE
 	default y if RISCV && 64BIT && TOOLCHAIN_HAS_VECTOR_CRYPTO && \
 		     RISCV_EFFICIENT_VECTOR_UNALIGNED_ACCESS

@@ -275,7 +275,7 @@ config CRYPTO_LIB_SHA512_ARCH
 	depends on CRYPTO_LIB_SHA512 && !UML
 	default y if ARM && !CPU_V7M
 	default y if ARM64
-	default y if MIPS && CPU_CAVIUM_OCTEON
+	default y if MIPS && CPU_CAVIUM_OCTEON && CPU_BIG_ENDIAN
 	default y if RISCV && 64BIT && TOOLCHAIN_HAS_VECTOR_CRYPTO && \
 		     RISCV_EFFICIENT_VECTOR_UNALIGNED_ACCESS
 	default y if S390

base-commit: 4403278e4ea2f654f8130a5c03eb8b4516a0f201

Signature · 1 line
2.56.0
maintainer Acked-by on v1 1/1
#1 lore raw
Quoted 42 lines · Eric Biggers

Kernels built for the MIPS64-based Cavium Octeon SoCs are normally big-endian, but little-endian builds are also supported. Currently, the SHA-1, SHA-256, and SHA-512 code using the Octeon crypto co-processor is enabled in both builds.

This code is untestable without the hardware. However, based on the code itself, it is implausible that it computes hash values correctly in little-endian builds. Such builds write many incorrect values to COP2:

- SHA-1 and SHA-256: The 64-bit integer that contains the last two 32-bit message words of each block is written to COP2 entirely byte-reflected, due to missing endianness conversion in octeon_sha1_start() and octeon_sha256_start() to compensate for using native 64-bit loads from the message bytes. This differs from all the earlier message words which are written correctly.

Furthermore, the state is written to COP2 with each 32-bit word byte-reflected within each 64-bit integer, due to incorrect use of 64-bit endianness conversion in write_octeon_64bit_hash_dword() when the state is kept in memory in native-endian 32-bit words.

- SHA-512: All the 64-bit message words are written to COP2 byte-reflected, due to missing endianness conversion in write_octeon_64bit_block_sha512() and octeon_sha512_start(). The SHA-512 state words seem to be written correctly.

Big-endian kernels aren't affected by these bugs. These bugs also aren't new; this code has been broken on little-endian ever since it and Octeon little-endian support were first added in v4.1.

Commit d2a948d2db68 ("MIPS: Octeon: Make octeon-md5 driver endian-agnostic") made the MD5 code work on little-endian kernels by adding 64-bit endianness conversions to the COP2 macros used by MD5 (some of which are shared by SHA-1 and SHA-256, despite those algorithms keeping the state words in native-endian instead of MD5's little-endian, causing some of the strange behavior described above). However, SHA-1, SHA-256, and SHA-512 were never fixed to work on little-endian kernels.

Therefore, disable the Octeon SHA-1, SHA-256, and SHA-512 code in little-endian kernels. This causes the generic code that actually computes hash values correctly to be used instead.

Quoted 6 lines
Fixes 82be2dcfa6a1 ("crypto: octeon - add SHA1 module")
Fixes c3d0def62001 ("crypto: octeon - add SHA256 module")
Fixes fbaa4dfd51a0 ("crypto: octeon - add SHA512 module")
Cc [email protected]
Signed-off-by Eric Biggers <[email protected]>

---

Acked-by Ard Biesheuvel <[email protected]>
author maintainer Applied
#2 lore raw
In reply to Eric Biggers
Quoted 4 lines · Eric Biggers

Therefore, disable the Octeon SHA-1, SHA-256, and SHA-512 code in little-endian kernels. This causes the generic code that actually computes hash values correctly to be used instead.

Quoted 8 lines
Fixes 82be2dcfa6a1 ("crypto: octeon - add SHA1 module")
Fixes c3d0def62001 ("crypto: octeon - add SHA256 module")
Fixes fbaa4dfd51a0 ("crypto: octeon - add SHA512 module")
Cc [email protected]
Signed-off-by Eric Biggers <[email protected]>

---

This patch is intended to be taken through libcrypto-fixes.

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=libcrypto-fixes

- Eric