Add bpf_crypto_shash module that registers a hash type with the BPF crypto infrastructure, enabling BPF programs to access kernel hash algorithms through a unified interface.
Update the bpf_crypto_type interface with hash-specific callbacks: - alloc_tfm: Allocates crypto_shash context with proper descriptor size - free_tfm: Releases hash transform and context memory - has_algo: Checks algorithm availability via crypto_has_shash() - hash: Performs single-shot hashing via crypto_shash_digest() - digestsize: Returns the output size for the hash algorithm - get_flags: Exposes transform flags to BPF programs
Update bpf_shash_ctx to contain crypto_shash transform and shash_desc descriptor to accommodate algorithm-specific descriptor requirements.
Signed-off-by: Daniel Hodges git@danielhodges.dev --- MAINTAINERS | 1 + crypto/Makefile | 3 ++ crypto/bpf_crypto_shash.c | 95 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 99 insertions(+) create mode 100644 crypto/bpf_crypto_shash.c
diff --git a/MAINTAINERS b/MAINTAINERS index 70c2b73b3941..05e0aee5693c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4712,6 +4712,7 @@ BPF [CRYPTO] M: Vadim Fedorenko vadim.fedorenko@linux.dev L: bpf@vger.kernel.org S: Maintained +F: crypto/bpf_crypto_shash.c F: crypto/bpf_crypto_skcipher.c F: include/linux/bpf_crypto.h F: kernel/bpf/crypto.c diff --git a/crypto/Makefile b/crypto/Makefile index 16a35649dd91..853dff375906 100644 --- a/crypto/Makefile +++ b/crypto/Makefile @@ -30,6 +30,9 @@ obj-$(CONFIG_CRYPTO_ECHAINIV) += echainiv.o crypto_hash-y += ahash.o crypto_hash-y += shash.o obj-$(CONFIG_CRYPTO_HASH2) += crypto_hash.o +ifeq ($(CONFIG_BPF_SYSCALL),y) +obj-$(CONFIG_CRYPTO_HASH2) += bpf_crypto_shash.o +endif
obj-$(CONFIG_CRYPTO_AKCIPHER2) += akcipher.o obj-$(CONFIG_CRYPTO_SIG2) += sig.o diff --git a/crypto/bpf_crypto_shash.c b/crypto/bpf_crypto_shash.c new file mode 100644 index 000000000000..95c178ec0ce8 --- /dev/null +++ b/crypto/bpf_crypto_shash.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ +#include <linux/types.h> +#include <linux/module.h> +#include <linux/bpf_crypto.h> +#include <crypto/hash.h> + +struct bpf_shash_ctx { + struct crypto_shash *tfm; + struct shash_desc desc; +}; + +static void *bpf_crypto_shash_alloc_tfm(const char *algo) +{ + struct bpf_shash_ctx *ctx; + struct crypto_shash *tfm; + + tfm = crypto_alloc_shash(algo, 0, 0); + if (IS_ERR(tfm)) + return tfm; + + ctx = kzalloc(sizeof(*ctx) + crypto_shash_descsize(tfm), GFP_KERNEL); + if (!ctx) { + crypto_free_shash(tfm); + return ERR_PTR(-ENOMEM); + } + + ctx->tfm = tfm; + ctx->desc.tfm = tfm; + + return ctx; +} + +static void bpf_crypto_shash_free_tfm(void *tfm) +{ + struct bpf_shash_ctx *ctx = tfm; + + crypto_free_shash(ctx->tfm); + kfree(ctx); +} + +static int bpf_crypto_shash_has_algo(const char *algo) +{ + return crypto_has_shash(algo, 0, 0); +} + +static int bpf_crypto_shash_hash(void *tfm, const u8 *data, u8 *out, + unsigned int len) +{ + struct bpf_shash_ctx *ctx = tfm; + + return crypto_shash_digest(&ctx->desc, data, len, out); +} + +static unsigned int bpf_crypto_shash_digestsize(void *tfm) +{ + struct bpf_shash_ctx *ctx = tfm; + + return crypto_shash_digestsize(ctx->tfm); +} + +static u32 bpf_crypto_shash_get_flags(void *tfm) +{ + struct bpf_shash_ctx *ctx = tfm; + + return crypto_shash_get_flags(ctx->tfm); +} + +static const struct bpf_crypto_type bpf_crypto_shash_type = { + .alloc_tfm = bpf_crypto_shash_alloc_tfm, + .free_tfm = bpf_crypto_shash_free_tfm, + .has_algo = bpf_crypto_shash_has_algo, + .hash = bpf_crypto_shash_hash, + .digestsize = bpf_crypto_shash_digestsize, + .get_flags = bpf_crypto_shash_get_flags, + .owner = THIS_MODULE, + .name = "hash", +}; + +static int __init bpf_crypto_shash_init(void) +{ + return bpf_crypto_register_type(&bpf_crypto_shash_type); +} + +static void __exit bpf_crypto_shash_exit(void) +{ + int err = bpf_crypto_unregister_type(&bpf_crypto_shash_type); + + WARN_ON_ONCE(err); +} + +module_init(bpf_crypto_shash_init); +module_exit(bpf_crypto_shash_exit); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Hash algorithm support for BPF");