[PATCH 5.15,5.10] lib/crypto: mips: Disable Octeon SHA code on little-endian kernels

[PATCH 5.15,5.10] lib/crypto: mips: Disable Octeon SHA code on little-endian kernels

[Eric Biggers]

commit dd2a4edb26e1c78823c50ba10c42f2d3de2e5ec4 upstream.

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: stable@vger.kernel.org
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://patch.msgid.link/20261022054450.20746-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 crypto/Kconfig | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 126d4699f06f7..6cfd33de36c15 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -868,7 +868,7 @@ config CRYPTO_SHA512_SSSE3
 
 config CRYPTO_SHA1_OCTEON
 	tristate "SHA1 digest algorithm (OCTEON)"
-	depends on CPU_CAVIUM_OCTEON
+	depends on CPU_CAVIUM_OCTEON && CPU_BIG_ENDIAN
 	select CRYPTO_SHA1
 	select CRYPTO_HASH
 	help
@@ -922,7 +922,7 @@ config CRYPTO_SHA256_PPC_SPE
 
 config CRYPTO_SHA256_OCTEON
 	tristate "SHA224 and SHA256 digest algorithm (OCTEON)"
-	depends on CPU_CAVIUM_OCTEON
+	depends on CPU_CAVIUM_OCTEON && CPU_BIG_ENDIAN
 	select CRYPTO_SHA256
 	select CRYPTO_HASH
 	help
@@ -952,7 +952,7 @@ config CRYPTO_SHA512
 
 config CRYPTO_SHA512_OCTEON
 	tristate "SHA384 and SHA512 digest algorithms (OCTEON)"
-	depends on CPU_CAVIUM_OCTEON
+	depends on CPU_CAVIUM_OCTEON && CPU_BIG_ENDIAN
 	select CRYPTO_SHA512
 	select CRYPTO_HASH
 	help

base-commit: 29c6cdaac04a6989a7ed4ae4275ce4244e617f58
-- 
2.56.0