RE: [PATCH 0/11] crypto: CFI fixes

Elliott, Robert (Servers)
2022-11-18T15:44:36Z

> -----Original Message-----
> From: Eric Biggers <ebiggers@kernel.org>
> Sent: Friday, November 18, 2022 3:02 AM
> To: linux-crypto@vger.kernel.org
> Cc: x86@kernel.org; linux-arm-kernel@lists.infradead.org; Sami Tolvanen
> <samitolvanen@google.com>
> Subject: [PATCH 0/11] crypto: CFI fixes
>
> This series fixes some crashes when CONFIG_CFI_CLANG (Control Flow
> Integrity) is enabled, with the new CFI implementation that was merged
> in 6.1 and is supported on x86. Some of them were unconditional
> crashes, while others depended on whether the compiler optimized out the
> indirect calls or not. This series also simplifies some code that was
> intended to work around limitations of the old CFI implementation and is
> unnecessary for the new CFI implementation.

Some of the x86 modules EXPORT their asm functions. Does that leave them
at risk of being called indirectly?

arch/x86/crypto/camellia-aesni-avx-asm_64.S:SYM_FUNC_START(camellia_ecb_dec_16way)
arch/x86/crypto/camellia-aesni-avx-asm_64.S:SYM_FUNC_START(camellia_ecb_enc_16way)
arch/x86/crypto/camellia-aesni-avx-asm_64.S:SYM_FUNC_START(camellia_cbc_dec_16way)
arch/x86/crypto/camellia_aesni_avx_glue.c:asmlinkage void camellia_ecb_enc_16way(const void *ctx, u8 *dst, const u8 *src);
arch/x86/crypto/camellia_aesni_avx_glue.c:EXPORT_SYMBOL_GPL(camellia_ecb_enc_16way);
arch/x86/crypto/camellia_aesni_avx_glue.c:asmlinkage void camellia_ecb_dec_16way(const void *ctx, u8 *dst, const u8 *src);
arch/x86/crypto/camellia_aesni_avx_glue.c:EXPORT_SYMBOL_GPL(camellia_ecb_dec_16way);
arch/x86/crypto/camellia_aesni_avx_glue.c:asmlinkage void camellia_cbc_dec_16way(const void *ctx, u8 *dst, const u8 *src);
arch/x86/crypto/camellia_aesni_avx_glue.c:EXPORT_SYMBOL_GPL(camellia_cbc_dec_16way);

arch/x86/crypto/twofish-x86_64-asm_64-3way.S:SYM_FUNC_START(__twofish_enc_blk_3way)
arch/x86/crypto/twofish.h:asmlinkage void __twofish_enc_blk_3way(const void *ctx, u8 *dst, const u8 *src,
arch/x86/crypto/twofish_glue_3way.c:EXPORT_SYMBOL_GPL(__twofish_enc_blk_3way);

A few of the x86 asm functions used by C code are not referenced with
asmlinkage like all the others. They're not EXPORTed, though, so whether
they're indirectly used can be determined.

u32 crc32_pclmul_le_16(unsigned char const *buffer, size_t len, u32 crc32);

void clmul_ghash_mul(char *dst, const u128 *shash);

void clmul_ghash_update(char *dst, const char *src, unsigned int srclen,
const u128 *shash);