[PATCH bpf-next v5 0/7] Add cryptographic hash and signature verification kfuncs to BPF

[PATCH bpf-next v5 0/7] Add cryptographic hash and signature verification kfuncs to BPF

[Daniel Hodges]

This patch series enhances BPF's cryptographic functionality by introducing
kernel functions for SHA hashing and ECDSA signature verification. The changes
enable BPF programs to verify data integrity and authenticity across
networking, security, and observability use cases.

The series addresses two gaps in BPF's cryptographic toolkit:

1. Cryptographic hashing - supports content verification and message digest
   preparation
2. Asymmetric signature verification - allows validation of signed data
   without requiring private keys in the datapath

Use cases include:
- Verifying signed network packets or application data in XDP/TC programs
- Integrity checks within tracing and security monitoring
- Zero-trust security models with BPF-based credential verification
- Content-addressed storage in BPF-based filesystems

The implementation leverages existing BPF patterns: it uses bpf_dynptr for
memory safety, reuses kernel crypto libraries (lib/crypto/sha256.c and
crypto/ecdsa.c) rather than reimplementing algorithms, and provides
context-based APIs supporting multiple program types.

v1: https://lore.kernel.org/bpf/20251117211413.1394-1-git@danielhodges.dev/

v2: https://lore.kernel.org/bpf/20251205173923.31740-1-git@danielhodges.dev/
- Fixed redundant __bpf_dynptr_is_rdonly() checks (Vadim)
- Added BPF hash algorithm type registration module in crypto/ subsystem
- Added CONFIG_CRYPTO_HASH2 guards around bpf_crypto_hash() kfunc and its
  BTF registration, matching the pattern used for CONFIG_CRYPTO_ECDSA
- Added mandatory digestsize validation for hash operations

v3: https://lore.kernel.org/bpf/20251208030117.18892-1-git@danielhodges.dev/
- Fixed patch ordering - header changes now in separate first commit before
  crypto module to ensure bisectability (bot+bpf-ci)
- Fixed type mismatch - changed u32 to u64 for dynptr sizes in
  bpf_crypto_hash() to match __bpf_dynptr_size() return type (Mykyta)
- Added CONFIG_CRYPTO_ECDSA to selftest config (Song)
- Refactored test code duplication with setup_skel() helper (Song)
- Added copyright notices to all new files

v4: https://lore.kernel.org/bpf/20260105173755.22515-1-git@danielhodges.dev/
- Reused common bpf_crypto_ctx structure for hash and signature operations
  instead of separate context types (Song)
- Fixed integer truncation in bpf_crypto_hash when data_len > UINT_MAX
- Corrected KF_RCU flags for ECDSA kfuncs (only bpf_ecdsa_verify needs KF_RCU)
- Updated MAINTAINERS file in test patches
- Refactored selftests to use crypto_common.h for kfunc declarations

v5:
- Fixed bisectability: moved bpf_crypto_type_id enum and type_id field
  introduction to the hash module commit, before it's used by hash kfunc
- Renamed kfuncs from bpf_ecdsa_* to bpf_sig_* since signature verification
  is not ECDSA-specific (Vadim)
- Added NULL checks in bpf_crypto_sig wrapper functions for optional
  digest_size and max_size callbacks to prevent NULL pointer dereference
- Added extra validation in bpf_sig_digestsize/bpf_sig_maxsize kfuncs to
  return -EOPNOTSUPP when underlying algorithm returns 0
- Renamed test files from ecdsa_verify to sig_verify for consistency

Daniel Hodges (7):
  bpf: Extend bpf_crypto_type with hash operations
  crypto: Add BPF hash algorithm type registration module
  crypto: Add BPF signature algorithm type registration module
  bpf: Add hash kfunc for cryptographic hashing
  selftests/bpf: Add tests for bpf_crypto_hash kfunc
  bpf: Add signature verification kfuncs
  selftests/bpf: Add tests for signature verification kfuncs

 MAINTAINERS                                   |   6 +
 crypto/Makefile                               |   6 +
 crypto/bpf_crypto_shash.c                     |  96 ++++++
 crypto/bpf_crypto_sig.c                       |  89 ++++++
 crypto/bpf_crypto_skcipher.c                  |   1 +
 include/linux/bpf_crypto.h                    |  13 +
 kernel/bpf/crypto.c                           | 204 ++++++++++++-
 tools/testing/selftests/bpf/config            |   2 +
 .../selftests/bpf/prog_tests/crypto_hash.c    | 210 +++++++++++++
 .../selftests/bpf/prog_tests/sig_verify.c     | 163 ++++++++++
 .../selftests/bpf/progs/crypto_common.h       |   8 +
 .../testing/selftests/bpf/progs/crypto_hash.c | 235 ++++++++++++++
 .../testing/selftests/bpf/progs/sig_verify.c  | 286 ++++++++++++++++++
 13 files changed, 1310 insertions(+), 9 deletions(-)
 create mode 100644 crypto/bpf_crypto_shash.c
 create mode 100644 crypto/bpf_crypto_sig.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/crypto_hash.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/sig_verify.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_hash.c
 create mode 100644 tools/testing/selftests/bpf/progs/sig_verify.c

-- 
2.52.0

[PATCH bpf-next v5 1/7] bpf: Extend bpf_crypto_type with hash operations

[Daniel Hodges]

Add hash operation callbacks to bpf_crypto_type structure:
 - hash(): Performs hashing operation on input data
 - digestsize(): Returns the output size for the hash algorithm

These additions enable BPF programs to use cryptographic hash functions
through the unified bpf_crypto_type interface, supporting use cases such
as content verification, integrity checking, and data authentication.

Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 include/linux/bpf_crypto.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/bpf_crypto.h b/include/linux/bpf_crypto.h
index a41e71d4e2d9..c84371cc4e47 100644
--- a/include/linux/bpf_crypto.h
+++ b/include/linux/bpf_crypto.h
@@ -11,8 +11,10 @@ struct bpf_crypto_type {
 	int (*setauthsize)(void *tfm, unsigned int authsize);
 	int (*encrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
 	int (*decrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
+	int (*hash)(void *tfm, const u8 *data, u8 *out, unsigned int len);
 	unsigned int (*ivsize)(void *tfm);
 	unsigned int (*statesize)(void *tfm);
+	unsigned int (*digestsize)(void *tfm);
 	u32 (*get_flags)(void *tfm);
 	struct module *owner;
 	char name[14];
-- 
2.52.0

[PATCH bpf-next v5 2/7] crypto: Add BPF hash algorithm type registration module

[Daniel Hodges]

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  | 96 ++++++++++++++++++++++++++++++++++++++
 include/linux/bpf_crypto.h |  7 +++
 4 files changed, 107 insertions(+)
 create mode 100644 crypto/bpf_crypto_shash.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 491d567f7dc8..4e9b369acd1c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4713,6 +4713,7 @@ 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..6e9b0d757ec9
--- /dev/null
+++ b/crypto/bpf_crypto_shash.c
@@ -0,0 +1,96 @@
+// 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,
+	.type_id	= BPF_CRYPTO_TYPE_HASH,
+	.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");
diff --git a/include/linux/bpf_crypto.h b/include/linux/bpf_crypto.h
index c84371cc4e47..cf2c66f9782b 100644
--- a/include/linux/bpf_crypto.h
+++ b/include/linux/bpf_crypto.h
@@ -3,6 +3,12 @@
 #ifndef _BPF_CRYPTO_H
 #define _BPF_CRYPTO_H
 
+enum bpf_crypto_type_id {
+	BPF_CRYPTO_TYPE_SKCIPHER = 1,
+	BPF_CRYPTO_TYPE_HASH,
+	BPF_CRYPTO_TYPE_SIG,
+};
+
 struct bpf_crypto_type {
 	void *(*alloc_tfm)(const char *algo);
 	void (*free_tfm)(void *tfm);
@@ -17,6 +23,7 @@ struct bpf_crypto_type {
 	unsigned int (*digestsize)(void *tfm);
 	u32 (*get_flags)(void *tfm);
 	struct module *owner;
+	enum bpf_crypto_type_id type_id;
 	char name[14];
 };
 
-- 
2.52.0

[PATCH bpf-next v5 3/7] crypto: Add BPF signature algorithm type registration module

[Daniel Hodges]

Add a new bpf_crypto_sig module that registers signature verification
algorithms with the BPF crypto type system. This enables signature
operations (like ECDSA) to use the unified bpf_crypto_ctx structure
instead of requiring separate context types.

Changes:
- Add verify() callback to bpf_crypto_type for signature verification
- Add bpf_crypto_sig module with:
  - alloc_tfm/free_tfm for crypto_sig transform lifecycle
  - has_algo to check algorithm availability
  - setkey for public key configuration
  - verify for signature verification
  - get_flags for crypto API flags

This allows ECDSA and other signature verification operations to
integrate with the existing BPF crypto infrastructure.

Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 MAINTAINERS                |  1 +
 crypto/Makefile            |  3 ++
 crypto/bpf_crypto_sig.c    | 67 ++++++++++++++++++++++++++++++++++++++
 include/linux/bpf_crypto.h |  2 ++
 4 files changed, 73 insertions(+)
 create mode 100644 crypto/bpf_crypto_sig.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4e9b369acd1c..62d712a1f730 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4714,6 +4714,7 @@ M:	Vadim Fedorenko <vadim.fedorenko@linux.dev>
 L:	bpf@vger.kernel.org
 S:	Maintained
 F:	crypto/bpf_crypto_shash.c
+F:	crypto/bpf_crypto_sig.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 853dff375906..c9ab98b57bc0 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -36,6 +36,9 @@ endif
 
 obj-$(CONFIG_CRYPTO_AKCIPHER2) += akcipher.o
 obj-$(CONFIG_CRYPTO_SIG2) += sig.o
+ifeq ($(CONFIG_BPF_SYSCALL),y)
+obj-$(CONFIG_CRYPTO_SIG2) += bpf_crypto_sig.o
+endif
 obj-$(CONFIG_CRYPTO_KPP2) += kpp.o
 obj-$(CONFIG_CRYPTO_HKDF) += hkdf.o
 
diff --git a/crypto/bpf_crypto_sig.c b/crypto/bpf_crypto_sig.c
new file mode 100644
index 000000000000..1d6521a066be
--- /dev/null
+++ b/crypto/bpf_crypto_sig.c
@@ -0,0 +1,67 @@
+// 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 <linux/crypto.h>
+#include <crypto/sig.h>
+
+static void *bpf_crypto_sig_alloc_tfm(const char *algo)
+{
+	return crypto_alloc_sig(algo, 0, 0);
+}
+
+static void bpf_crypto_sig_free_tfm(void *tfm)
+{
+	crypto_free_sig(tfm);
+}
+
+static int bpf_crypto_sig_has_algo(const char *algo)
+{
+	return crypto_has_alg(algo, CRYPTO_ALG_TYPE_SIG, CRYPTO_ALG_TYPE_MASK);
+}
+
+static u32 bpf_crypto_sig_get_flags(void *tfm)
+{
+	return crypto_tfm_get_flags(crypto_sig_tfm(tfm));
+}
+
+static int bpf_crypto_sig_setkey(void *tfm, const u8 *key, unsigned int keylen)
+{
+	return crypto_sig_set_pubkey(tfm, key, keylen);
+}
+
+static int bpf_crypto_sig_verify(void *tfm, const u8 *sig, unsigned int sig_len,
+				 const u8 *msg, unsigned int msg_len)
+{
+	return crypto_sig_verify(tfm, sig, sig_len, msg, msg_len);
+}
+
+static const struct bpf_crypto_type bpf_crypto_sig_type = {
+	.alloc_tfm	= bpf_crypto_sig_alloc_tfm,
+	.free_tfm	= bpf_crypto_sig_free_tfm,
+	.has_algo	= bpf_crypto_sig_has_algo,
+	.get_flags	= bpf_crypto_sig_get_flags,
+	.setkey		= bpf_crypto_sig_setkey,
+	.verify		= bpf_crypto_sig_verify,
+	.owner		= THIS_MODULE,
+	.type_id	= BPF_CRYPTO_TYPE_SIG,
+	.name		= "sig",
+};
+
+static int __init bpf_crypto_sig_init(void)
+{
+	return bpf_crypto_register_type(&bpf_crypto_sig_type);
+}
+
+static void __exit bpf_crypto_sig_exit(void)
+{
+	int err = bpf_crypto_unregister_type(&bpf_crypto_sig_type);
+
+	WARN_ON_ONCE(err);
+}
+
+module_init(bpf_crypto_sig_init);
+module_exit(bpf_crypto_sig_exit);
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Signature algorithm support for BPF");
diff --git a/include/linux/bpf_crypto.h b/include/linux/bpf_crypto.h
index cf2c66f9782b..363ed72561f4 100644
--- a/include/linux/bpf_crypto.h
+++ b/include/linux/bpf_crypto.h
@@ -18,6 +18,8 @@ struct bpf_crypto_type {
 	int (*encrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
 	int (*decrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
 	int (*hash)(void *tfm, const u8 *data, u8 *out, unsigned int len);
+	int (*verify)(void *tfm, const u8 *sig, unsigned int sig_len,
+		      const u8 *msg, unsigned int msg_len);
 	unsigned int (*ivsize)(void *tfm);
 	unsigned int (*statesize)(void *tfm);
 	unsigned int (*digestsize)(void *tfm);
-- 
2.52.0

[PATCH bpf-next v5 4/7] bpf: Add hash kfunc for cryptographic hashing

[Daniel Hodges]

Extend bpf_crypto_type structure with hash operations:
 - hash(): Performs hashing operation
 - digestsize(): Returns hash output size

Update bpf_crypto_ctx_create() to support keyless operations:
 - Hash algorithms don't require keys, unlike ciphers
 - Only validates key presence if type->setkey is defined
 - Conditionally sets IV/state length for cipher operations only

Add bpf_crypto_hash() kfunc that works with any hash algorithm
registered in the kernel's crypto API through the BPF crypto type
system. This enables BPF programs to compute cryptographic hashes for
use cases such as content verification, integrity checking, and data
authentication.

Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 kernel/bpf/crypto.c | 87 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 78 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 7e75a1936256..c8f354b1a2cb 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -139,7 +139,7 @@ __bpf_kfunc_start_defs();
  * It may return NULL if no memory is available.
  * @params:	pointer to struct bpf_crypto_params which contains all the
  *		details needed to initialise crypto context.
- * @params__sz:	size of steuct bpf_crypto_params usef by bpf program
+ * @params__sz:	size of struct bpf_crypto_params used by bpf program
  * @err:	integer to store error code when NULL is returned.
  */
 __bpf_kfunc struct bpf_crypto_ctx *
@@ -171,7 +171,12 @@ bpf_crypto_ctx_create(const struct bpf_crypto_params *params, u32 params__sz,
 		goto err_module_put;
 	}
 
-	if (!params->key_len || params->key_len > sizeof(params->key)) {
+	/* Hash operations don't require a key, but cipher operations do */
+	if (params->key_len > sizeof(params->key)) {
+		*err = -EINVAL;
+		goto err_module_put;
+	}
+	if (!params->key_len && type->setkey) {
 		*err = -EINVAL;
 		goto err_module_put;
 	}
@@ -195,16 +200,23 @@ bpf_crypto_ctx_create(const struct bpf_crypto_params *params, u32 params__sz,
 			goto err_free_tfm;
 	}
 
-	*err = type->setkey(ctx->tfm, params->key, params->key_len);
-	if (*err)
-		goto err_free_tfm;
+	if (params->key_len) {
+		if (!type->setkey) {
+			*err = -EINVAL;
+			goto err_free_tfm;
+		}
+		*err = type->setkey(ctx->tfm, params->key, params->key_len);
+		if (*err)
+			goto err_free_tfm;
 
-	if (type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY) {
-		*err = -EINVAL;
-		goto err_free_tfm;
+		if (type->get_flags(ctx->tfm) & CRYPTO_TFM_NEED_KEY) {
+			*err = -EINVAL;
+			goto err_free_tfm;
+		}
 	}
 
-	ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);
+	if (type->ivsize && type->statesize)
+		ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);
 
 	refcount_set(&ctx->usage, 1);
 
@@ -349,6 +361,58 @@ __bpf_kfunc int bpf_crypto_encrypt(struct bpf_crypto_ctx *ctx,
 	return bpf_crypto_crypt(ctx, src_kern, dst_kern, siv_kern, false);
 }
 
+#if IS_ENABLED(CONFIG_CRYPTO_HASH2)
+/**
+ * bpf_crypto_hash() - Compute hash using configured context
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ * @data:	bpf_dynptr to the input data to hash. Must be a trusted pointer.
+ * @out:	bpf_dynptr to the output buffer. Must be a trusted pointer.
+ *
+ * Computes hash of the input data using the crypto context. The output buffer
+ * must be at least as large as the digest size of the hash algorithm.
+ */
+__bpf_kfunc int bpf_crypto_hash(struct bpf_crypto_ctx *ctx,
+				const struct bpf_dynptr *data,
+				const struct bpf_dynptr *out)
+{
+	const struct bpf_dynptr_kern *data_kern = (struct bpf_dynptr_kern *)data;
+	const struct bpf_dynptr_kern *out_kern = (struct bpf_dynptr_kern *)out;
+	unsigned int digestsize;
+	u64 data_len, out_len;
+	const u8 *data_ptr;
+	u8 *out_ptr;
+
+	if (ctx->type->type_id != BPF_CRYPTO_TYPE_HASH)
+		return -EINVAL;
+
+	if (!ctx->type->hash)
+		return -EOPNOTSUPP;
+
+	data_len = __bpf_dynptr_size(data_kern);
+	out_len = __bpf_dynptr_size(out_kern);
+
+	if (data_len == 0 || data_len > UINT_MAX)
+		return -EINVAL;
+
+	if (!ctx->type->digestsize)
+		return -EOPNOTSUPP;
+
+	digestsize = ctx->type->digestsize(ctx->tfm);
+	if (out_len < digestsize)
+		return -EINVAL;
+
+	data_ptr = __bpf_dynptr_data(data_kern, data_len);
+	if (!data_ptr)
+		return -EINVAL;
+
+	out_ptr = __bpf_dynptr_data_rw(out_kern, out_len);
+	if (!out_ptr)
+		return -EINVAL;
+
+	return ctx->type->hash(ctx->tfm, data_ptr, out_ptr, data_len);
+}
+#endif /* CONFIG_CRYPTO_HASH2 */
+
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(crypt_init_kfunc_btf_ids)
@@ -365,6 +429,9 @@ static const struct btf_kfunc_id_set crypt_init_kfunc_set = {
 BTF_KFUNCS_START(crypt_kfunc_btf_ids)
 BTF_ID_FLAGS(func, bpf_crypto_decrypt, KF_RCU)
 BTF_ID_FLAGS(func, bpf_crypto_encrypt, KF_RCU)
+#if IS_ENABLED(CONFIG_CRYPTO_HASH2)
+BTF_ID_FLAGS(func, bpf_crypto_hash, KF_RCU)
+#endif
 BTF_KFUNCS_END(crypt_kfunc_btf_ids)
 
 static const struct btf_kfunc_id_set crypt_kfunc_set = {
@@ -389,6 +456,8 @@ static int __init crypto_kfunc_init(void)
 	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &crypt_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_ACT, &crypt_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &crypt_kfunc_set);
+	/* Register for SYSCALL programs to enable testing and debugging */
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &crypt_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL,
 					       &crypt_init_kfunc_set);
 	return  ret ?: register_btf_id_dtor_kfuncs(bpf_crypto_dtors,
-- 
2.52.0

[PATCH bpf-next v5 5/7] selftests/bpf: Add tests for bpf_crypto_hash kfunc

[Daniel Hodges]

Add selftests to validate the bpf_crypto_hash works properly. The tests
verify both correct functionality and proper error handling.

Test Data:
All tests use the well-known NIST test vector input "abc" and validate
against the standardized expected outputs for each algorithm. This ensures
the BPF kfunc wrappers correctly delegate to the kernel crypto library.

Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 MAINTAINERS                                   |   2 +
 tools/testing/selftests/bpf/config            |   2 +
 .../selftests/bpf/prog_tests/crypto_hash.c    | 210 ++++++++++++++++
 .../selftests/bpf/progs/crypto_common.h       |   2 +
 .../testing/selftests/bpf/progs/crypto_hash.c | 235 ++++++++++++++++++
 5 files changed, 451 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/crypto_hash.c
 create mode 100644 tools/testing/selftests/bpf/progs/crypto_hash.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 62d712a1f730..d23ea38b606f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4718,6 +4718,8 @@ F:	crypto/bpf_crypto_sig.c
 F:	crypto/bpf_crypto_skcipher.c
 F:	include/linux/bpf_crypto.h
 F:	kernel/bpf/crypto.c
+F:	tools/testing/selftests/bpf/prog_tests/crypto_hash.c
+F:	tools/testing/selftests/bpf/progs/crypto_hash.c
 
 BPF [DOCUMENTATION] (Related to Standardization)
 R:	David Vernet <void@manifault.com>
diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
index 558839e3c185..814804f71780 100644
--- a/tools/testing/selftests/bpf/config
+++ b/tools/testing/selftests/bpf/config
@@ -13,6 +13,8 @@ CONFIG_BPF_SYSCALL=y
 CONFIG_CGROUP_BPF=y
 CONFIG_CRYPTO_HMAC=y
 CONFIG_CRYPTO_SHA256=y
+CONFIG_CRYPTO_SHA512=y
+CONFIG_CRYPTO_HASH2=y
 CONFIG_CRYPTO_USER_API=y
 CONFIG_CRYPTO_USER_API_HASH=y
 CONFIG_CRYPTO_USER_API_SKCIPHER=y
diff --git a/tools/testing/selftests/bpf/prog_tests/crypto_hash.c b/tools/testing/selftests/bpf/prog_tests/crypto_hash.c
new file mode 100644
index 000000000000..0c78b5f46c9c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/crypto_hash.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include <test_progs.h>
+#include <errno.h>
+#include "crypto_hash.skel.h"
+
+/* NIST test vectors for SHA-256("abc") */
+static const unsigned char expected_sha256[32] = {
+	0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
+	0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
+	0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
+	0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad
+};
+
+/* NIST test vectors for SHA-384("abc") */
+static const unsigned char expected_sha384[48] = {
+	0xcb, 0x00, 0x75, 0x3f, 0x45, 0xa3, 0x5e, 0x8b,
+	0xb5, 0xa0, 0x3d, 0x69, 0x9a, 0xc6, 0x50, 0x07,
+	0x27, 0x2c, 0x32, 0xab, 0x0e, 0xde, 0xd1, 0x63,
+	0x1a, 0x8b, 0x60, 0x5a, 0x43, 0xff, 0x5b, 0xed,
+	0x80, 0x86, 0x07, 0x2b, 0xa1, 0xe7, 0xcc, 0x23,
+	0x58, 0xba, 0xec, 0xa1, 0x34, 0xc8, 0x25, 0xa7
+};
+
+/* NIST test vectors for SHA-512("abc") */
+static const unsigned char expected_sha512[64] = {
+	0xdd, 0xaf, 0x35, 0xa1, 0x93, 0x61, 0x7a, 0xba,
+	0xcc, 0x41, 0x73, 0x49, 0xae, 0x20, 0x41, 0x31,
+	0x12, 0xe6, 0xfa, 0x4e, 0x89, 0xa9, 0x7e, 0xa2,
+	0x0a, 0x9e, 0xee, 0xe6, 0x4b, 0x55, 0xd3, 0x9a,
+	0x21, 0x92, 0x99, 0x2a, 0x27, 0x4f, 0xc1, 0xa8,
+	0x36, 0xba, 0x3c, 0x23, 0xa3, 0xfe, 0xeb, 0xbd,
+	0x45, 0x4d, 0x44, 0x23, 0x64, 0x3c, 0xe8, 0x0e,
+	0x2a, 0x9a, 0xc9, 0x4f, 0xa5, 0x4c, 0xa4, 0x9f
+};
+
+static struct crypto_hash *setup_skel(void)
+{
+	struct crypto_hash *skel;
+
+	skel = crypto_hash__open_and_load();
+	if (!skel) {
+		/* Skip if kfuncs not available (CONFIG_CRYPTO_HASH2 not set) */
+		if (errno == ENOENT || errno == EINVAL) {
+			test__skip();
+			return NULL;
+		}
+		ASSERT_OK_PTR(skel, "crypto_hash__open_and_load");
+		return NULL;
+	}
+
+	return skel;
+}
+
+static void test_sha256_basic(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_sha256);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_sha256");
+	ASSERT_EQ(skel->data->sha256_status, 0, "sha256_status");
+	ASSERT_EQ(memcmp(skel->bss->sha256_output, expected_sha256, 32), 0,
+		  "sha256_output_match");
+
+	crypto_hash__destroy(skel);
+}
+
+static void test_sha384_basic(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+	prog_fd = bpf_program__fd(skel->progs.test_sha384);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_sha384");
+	ASSERT_EQ(skel->data->sha384_status, 0, "sha384_status");
+	ASSERT_EQ(memcmp(skel->bss->sha384_output, expected_sha384, 48), 0,
+		  "sha384_output_match");
+
+	crypto_hash__destroy(skel);
+}
+
+static void test_sha512_basic(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_sha512);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_sha512");
+	ASSERT_EQ(skel->data->sha512_status, 0, "sha512_status");
+	ASSERT_EQ(memcmp(skel->bss->sha512_output, expected_sha512, 64), 0,
+		  "sha512_output_match");
+
+	crypto_hash__destroy(skel);
+}
+
+static void test_sha256_invalid_params(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_sha256_zero_len);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_zero_len");
+	ASSERT_EQ(skel->data->sha256_status, 0, "zero_len_rejected");
+
+	crypto_hash__destroy(skel);
+}
+
+static void test_hash_with_key_rejected(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_hash_with_key_rejected);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_hash_with_key_rejected");
+	ASSERT_EQ(skel->data->hash_with_key_status, 0, "hash_with_key_rejected");
+
+	crypto_hash__destroy(skel);
+}
+
+static void test_hash_output_too_small(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_hash_output_too_small);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_hash_output_too_small");
+	ASSERT_EQ(skel->data->hash_output_too_small_status, 0, "hash_output_too_small");
+
+	crypto_hash__destroy(skel);
+}
+
+static void test_hash_on_skcipher_ctx(void)
+{
+	struct crypto_hash *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = setup_skel();
+	if (!skel)
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_hash_on_skcipher_ctx);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_hash_on_skcipher_ctx");
+	ASSERT_EQ(skel->data->hash_on_skcipher_status, 0, "hash_on_skcipher_rejected");
+
+	crypto_hash__destroy(skel);
+}
+
+void test_crypto_hash(void)
+{
+	if (test__start_subtest("sha256_basic"))
+		test_sha256_basic();
+	if (test__start_subtest("sha384_basic"))
+		test_sha384_basic();
+	if (test__start_subtest("sha512_basic"))
+		test_sha512_basic();
+	if (test__start_subtest("sha256_invalid_params"))
+		test_sha256_invalid_params();
+	if (test__start_subtest("hash_with_key_rejected"))
+		test_hash_with_key_rejected();
+	if (test__start_subtest("hash_output_too_small"))
+		test_hash_output_too_small();
+	if (test__start_subtest("hash_on_skcipher_ctx"))
+		test_hash_on_skcipher_ctx();
+}
diff --git a/tools/testing/selftests/bpf/progs/crypto_common.h b/tools/testing/selftests/bpf/progs/crypto_common.h
index 57dd7a68a8c3..2f04f08f890b 100644
--- a/tools/testing/selftests/bpf/progs/crypto_common.h
+++ b/tools/testing/selftests/bpf/progs/crypto_common.h
@@ -15,6 +15,8 @@ int bpf_crypto_encrypt(struct bpf_crypto_ctx *ctx, const struct bpf_dynptr *src,
 		       const struct bpf_dynptr *dst, const struct bpf_dynptr *iv) __ksym;
 int bpf_crypto_decrypt(struct bpf_crypto_ctx *ctx, const struct bpf_dynptr *src,
 		       const struct bpf_dynptr *dst, const struct bpf_dynptr *iv) __ksym;
+int bpf_crypto_hash(struct bpf_crypto_ctx *ctx, const struct bpf_dynptr *data,
+		    const struct bpf_dynptr *out) __ksym;
 
 struct __crypto_ctx_value {
 	struct bpf_crypto_ctx __kptr * ctx;
diff --git a/tools/testing/selftests/bpf/progs/crypto_hash.c b/tools/testing/selftests/bpf/progs/crypto_hash.c
new file mode 100644
index 000000000000..e6eacbc40607
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/crypto_hash.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_kfuncs.h"
+#include "crypto_common.h"
+
+unsigned char test_input[3] = "abc";
+
+/* Expected SHA-256 hash of "abc" */
+/* ba7816bf 8f01cfea 414140de 5dae2223 b00361a3 96177a9c b410ff61 f20015ad */
+unsigned char expected_sha256[32] = {
+	0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
+	0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
+	0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
+	0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad
+};
+
+/* Output buffers for test results */
+unsigned char sha256_output[32] = {};
+unsigned char sha384_output[48] = {};
+unsigned char sha512_output[64] = {};
+unsigned char small_output[16] = {}; /* Intentionally small for output_too_small test */
+
+int sha256_status = -1;
+int sha384_status = -1;
+int sha512_status = -1;
+int hash_with_key_status = -1;
+int hash_output_too_small_status = -1;
+int hash_on_skcipher_status = -1;
+
+SEC("syscall")
+int test_sha256(void *ctx)
+{
+	struct bpf_dynptr input_ptr, output_ptr;
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha256",
+		.key_len = 0,
+	};
+	int err = 0;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		sha256_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(test_input, sizeof(test_input), 0, &input_ptr);
+	bpf_dynptr_from_mem(sha256_output, sizeof(sha256_output), 0, &output_ptr);
+
+	sha256_status = bpf_crypto_hash(hash_ctx, &input_ptr, &output_ptr);
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+SEC("syscall")
+int test_sha384(void *ctx)
+{
+	struct bpf_dynptr input_ptr, output_ptr;
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha384",
+		.key_len = 0,
+	};
+	int err = 0;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		sha384_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(test_input, sizeof(test_input), 0, &input_ptr);
+	bpf_dynptr_from_mem(sha384_output, sizeof(sha384_output), 0, &output_ptr);
+
+	sha384_status = bpf_crypto_hash(hash_ctx, &input_ptr, &output_ptr);
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+SEC("syscall")
+int test_sha512(void *ctx)
+{
+	struct bpf_dynptr input_ptr, output_ptr;
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha512",
+		.key_len = 0,
+	};
+	int err = 0;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		sha512_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(test_input, sizeof(test_input), 0, &input_ptr);
+	bpf_dynptr_from_mem(sha512_output, sizeof(sha512_output), 0, &output_ptr);
+
+	sha512_status = bpf_crypto_hash(hash_ctx, &input_ptr, &output_ptr);
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+SEC("syscall")
+int test_sha256_zero_len(void *ctx)
+{
+	struct bpf_dynptr input_ptr, output_ptr;
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha256",
+		.key_len = 0,
+	};
+	int err = 0;
+	int ret;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		sha256_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(test_input, 0, 0, &input_ptr);
+	bpf_dynptr_from_mem(sha256_output, sizeof(sha256_output), 0, &output_ptr);
+
+	ret = bpf_crypto_hash(hash_ctx, &input_ptr, &output_ptr);
+	sha256_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+/* Test that hash context creation with a key is rejected */
+SEC("syscall")
+int test_hash_with_key_rejected(void *ctx)
+{
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha256",
+		.key_len = 16, /* Hash algorithms don't support keys */
+	};
+	int err = 0;
+
+	/* Set some dummy key data */
+	params.key[0] = 0x01;
+	params.key[1] = 0x02;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		/* Expected: should fail with -EINVAL (-22) */
+		hash_with_key_status = (err == -22) ? 0 : err;
+		return 0;
+	}
+
+	/* Should not reach here - context creation should have failed */
+	hash_with_key_status = -1;
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+/* Test that hash with output buffer too small is rejected */
+SEC("syscall")
+int test_hash_output_too_small(void *ctx)
+{
+	struct bpf_dynptr input_ptr, output_ptr;
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha256",
+		.key_len = 0,
+	};
+	int err = 0;
+	int ret;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		hash_output_too_small_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(test_input, sizeof(test_input), 0, &input_ptr);
+	bpf_dynptr_from_mem(small_output, sizeof(small_output), 0, &output_ptr);
+
+	ret = bpf_crypto_hash(hash_ctx, &input_ptr, &output_ptr);
+	/* Expected: should fail with -EINVAL (-22) */
+	hash_output_too_small_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+/* Test that calling bpf_crypto_hash on skcipher context fails */
+SEC("syscall")
+int test_hash_on_skcipher_ctx(void *ctx)
+{
+	struct bpf_dynptr input_ptr, output_ptr;
+	struct bpf_crypto_ctx *cipher_ctx;
+	struct bpf_crypto_params params = {
+		.type = "skcipher",
+		.algo = "ecb(aes)",
+		.key_len = 16,
+	};
+	int err = 0;
+	int ret;
+
+	/* Set a valid AES-128 key */
+	params.key[0] = 0x00; params.key[1] = 0x01; params.key[2] = 0x02; params.key[3] = 0x03;
+	params.key[4] = 0x04; params.key[5] = 0x05; params.key[6] = 0x06; params.key[7] = 0x07;
+	params.key[8] = 0x08; params.key[9] = 0x09; params.key[10] = 0x0a; params.key[11] = 0x0b;
+	params.key[12] = 0x0c; params.key[13] = 0x0d; params.key[14] = 0x0e; params.key[15] = 0x0f;
+
+	cipher_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!cipher_ctx) {
+		hash_on_skcipher_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(test_input, sizeof(test_input), 0, &input_ptr);
+	bpf_dynptr_from_mem(sha256_output, sizeof(sha256_output), 0, &output_ptr);
+
+	ret = bpf_crypto_hash(cipher_ctx, &input_ptr, &output_ptr);
+	/* Expected: should fail with -EINVAL (-22) due to type_id mismatch */
+	hash_on_skcipher_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(cipher_ctx);
+	return 0;
+}
+
+char __license[] SEC("license") = "GPL";
-- 
2.52.0

[PATCH bpf-next v5 6/7] bpf: Add signature verification kfuncs

[Daniel Hodges]

Introduce bpf_sig_verify, bpf_sig_keysize, bpf_sig_digestsize,
and bpf_sig_maxsize kfuncs enabling BPF programs to verify digital
signatures using the kernel's crypto infrastructure.

This adds enum bpf_crypto_type_id for runtime type checking to ensure
operations are performed on the correct crypto context type. The enum
values are assigned to all crypto type modules (skcipher, hash, sig).

The verify kfunc takes a crypto context (initialized with the "sig"
type and appropriate algorithm like "ecdsa-nist-p256"), a message
digest, and a signature. It uses dynptr for memory access.

These kfuncs support any signature algorithm registered with the
crypto subsystem (e.g., ECDSA, RSA).

Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 crypto/bpf_crypto_sig.c      |  22 +++++++
 crypto/bpf_crypto_skcipher.c |   1 +
 include/linux/bpf_crypto.h   |   2 +
 kernel/bpf/crypto.c          | 117 +++++++++++++++++++++++++++++++++++
 4 files changed, 142 insertions(+)

diff --git a/crypto/bpf_crypto_sig.c b/crypto/bpf_crypto_sig.c
index 1d6521a066be..2dc82c5f9abb 100644
--- a/crypto/bpf_crypto_sig.c
+++ b/crypto/bpf_crypto_sig.c
@@ -37,6 +37,25 @@ static int bpf_crypto_sig_verify(void *tfm, const u8 *sig, unsigned int sig_len,
 	return crypto_sig_verify(tfm, sig, sig_len, msg, msg_len);
 }
 
+static unsigned int bpf_crypto_sig_keysize(void *tfm)
+{
+	return crypto_sig_keysize(tfm);
+}
+
+static unsigned int bpf_crypto_sig_digestsize(void *tfm)
+{
+	struct sig_alg *alg = crypto_sig_alg(tfm);
+
+	return alg->digest_size ? alg->digest_size(tfm) : 0;
+}
+
+static unsigned int bpf_crypto_sig_maxsize(void *tfm)
+{
+	struct sig_alg *alg = crypto_sig_alg(tfm);
+
+	return alg->max_size ? alg->max_size(tfm) : 0;
+}
+
 static const struct bpf_crypto_type bpf_crypto_sig_type = {
 	.alloc_tfm	= bpf_crypto_sig_alloc_tfm,
 	.free_tfm	= bpf_crypto_sig_free_tfm,
@@ -44,6 +63,9 @@ static const struct bpf_crypto_type bpf_crypto_sig_type = {
 	.get_flags	= bpf_crypto_sig_get_flags,
 	.setkey		= bpf_crypto_sig_setkey,
 	.verify		= bpf_crypto_sig_verify,
+	.keysize	= bpf_crypto_sig_keysize,
+	.digestsize	= bpf_crypto_sig_digestsize,
+	.maxsize	= bpf_crypto_sig_maxsize,
 	.owner		= THIS_MODULE,
 	.type_id	= BPF_CRYPTO_TYPE_SIG,
 	.name		= "sig",
diff --git a/crypto/bpf_crypto_skcipher.c b/crypto/bpf_crypto_skcipher.c
index a88798d3e8c8..79d310fbcc48 100644
--- a/crypto/bpf_crypto_skcipher.c
+++ b/crypto/bpf_crypto_skcipher.c
@@ -63,6 +63,7 @@ static const struct bpf_crypto_type bpf_crypto_lskcipher_type = {
 	.statesize	= bpf_crypto_lskcipher_statesize,
 	.get_flags	= bpf_crypto_lskcipher_get_flags,
 	.owner		= THIS_MODULE,
+	.type_id	= BPF_CRYPTO_TYPE_SKCIPHER,
 	.name		= "skcipher",
 };
 
diff --git a/include/linux/bpf_crypto.h b/include/linux/bpf_crypto.h
index 363ed72561f4..e0f946926f69 100644
--- a/include/linux/bpf_crypto.h
+++ b/include/linux/bpf_crypto.h
@@ -23,6 +23,8 @@ struct bpf_crypto_type {
 	unsigned int (*ivsize)(void *tfm);
 	unsigned int (*statesize)(void *tfm);
 	unsigned int (*digestsize)(void *tfm);
+	unsigned int (*keysize)(void *tfm);
+	unsigned int (*maxsize)(void *tfm);
 	u32 (*get_flags)(void *tfm);
 	struct module *owner;
 	enum bpf_crypto_type_id type_id;
diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index c8f354b1a2cb..6bc534cd4076 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -413,6 +413,117 @@ __bpf_kfunc int bpf_crypto_hash(struct bpf_crypto_ctx *ctx,
 }
 #endif /* CONFIG_CRYPTO_HASH2 */
 
+#if IS_ENABLED(CONFIG_CRYPTO_SIG2)
+/**
+ * bpf_sig_verify() - Verify digital signature using configured context
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ * @message:	bpf_dynptr to the message hash to verify. Must be a trusted pointer.
+ * @signature:	bpf_dynptr to the signature. Must be a trusted pointer.
+ *
+ * Verifies a digital signature over a message hash using the public key
+ * configured in the crypto context. Supports any signature algorithm
+ * registered with the crypto subsystem (e.g., ECDSA, RSA).
+ *
+ * Return: 0 on success (valid signature), negative error code on failure.
+ */
+__bpf_kfunc int bpf_sig_verify(struct bpf_crypto_ctx *ctx,
+				 const struct bpf_dynptr *message,
+				 const struct bpf_dynptr *signature)
+{
+	const struct bpf_dynptr_kern *msg_kern = (struct bpf_dynptr_kern *)message;
+	const struct bpf_dynptr_kern *sig_kern = (struct bpf_dynptr_kern *)signature;
+	u64 msg_len, sig_len;
+	const u8 *msg_ptr, *sig_ptr;
+
+	if (ctx->type->type_id != BPF_CRYPTO_TYPE_SIG)
+		return -EINVAL;
+
+	if (!ctx->type->verify)
+		return -EOPNOTSUPP;
+
+	msg_len = __bpf_dynptr_size(msg_kern);
+	sig_len = __bpf_dynptr_size(sig_kern);
+
+	if (msg_len == 0 || msg_len > UINT_MAX)
+		return -EINVAL;
+	if (sig_len == 0 || sig_len > UINT_MAX)
+		return -EINVAL;
+
+	msg_ptr = __bpf_dynptr_data(msg_kern, msg_len);
+	if (!msg_ptr)
+		return -EINVAL;
+
+	sig_ptr = __bpf_dynptr_data(sig_kern, sig_len);
+	if (!sig_ptr)
+		return -EINVAL;
+
+	return ctx->type->verify(ctx->tfm, sig_ptr, sig_len, msg_ptr, msg_len);
+}
+
+/**
+ * bpf_sig_keysize() - Get the key size for signature context
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ *
+ * Return: The key size in bytes, or negative error code on failure.
+ */
+__bpf_kfunc int bpf_sig_keysize(struct bpf_crypto_ctx *ctx)
+{
+	if (ctx->type->type_id != BPF_CRYPTO_TYPE_SIG)
+		return -EINVAL;
+
+	if (!ctx->type->keysize)
+		return -EOPNOTSUPP;
+
+	return ctx->type->keysize(ctx->tfm);
+}
+
+/**
+ * bpf_sig_digestsize() - Get the digest size for signature context
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ *
+ * Return: The digest size in bytes, or negative error code on failure.
+ */
+__bpf_kfunc int bpf_sig_digestsize(struct bpf_crypto_ctx *ctx)
+{
+	unsigned int size;
+
+	if (ctx->type->type_id != BPF_CRYPTO_TYPE_SIG)
+		return -EINVAL;
+
+	if (!ctx->type->digestsize)
+		return -EOPNOTSUPP;
+
+	size = ctx->type->digestsize(ctx->tfm);
+	if (!size)
+		return -EOPNOTSUPP;
+
+	return size;
+}
+
+/**
+ * bpf_sig_maxsize() - Get the maximum signature size for signature context
+ * @ctx:	The crypto context being used. The ctx must be a trusted pointer.
+ *
+ * Return: The maximum signature size in bytes, or negative error code on failure.
+ */
+__bpf_kfunc int bpf_sig_maxsize(struct bpf_crypto_ctx *ctx)
+{
+	unsigned int size;
+
+	if (ctx->type->type_id != BPF_CRYPTO_TYPE_SIG)
+		return -EINVAL;
+
+	if (!ctx->type->maxsize)
+		return -EOPNOTSUPP;
+
+	size = ctx->type->maxsize(ctx->tfm);
+	if (!size)
+		return -EOPNOTSUPP;
+
+	return size;
+}
+#endif /* CONFIG_CRYPTO_SIG2 */
+
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(crypt_init_kfunc_btf_ids)
@@ -432,6 +543,12 @@ BTF_ID_FLAGS(func, bpf_crypto_encrypt, KF_RCU)
 #if IS_ENABLED(CONFIG_CRYPTO_HASH2)
 BTF_ID_FLAGS(func, bpf_crypto_hash, KF_RCU)
 #endif
+#if IS_ENABLED(CONFIG_CRYPTO_SIG2)
+BTF_ID_FLAGS(func, bpf_sig_verify, KF_RCU)
+BTF_ID_FLAGS(func, bpf_sig_keysize)
+BTF_ID_FLAGS(func, bpf_sig_digestsize)
+BTF_ID_FLAGS(func, bpf_sig_maxsize)
+#endif
 BTF_KFUNCS_END(crypt_kfunc_btf_ids)
 
 static const struct btf_kfunc_id_set crypt_kfunc_set = {
-- 
2.52.0

[PATCH bpf-next v5 7/7] selftests/bpf: Add tests for signature verification kfuncs

[Daniel Hodges]

Add tests for the signature verification kfuncs:

1. test_ecdsa_verify_valid_signature: Verifies that a valid ECDSA
   signature over a known message hash is correctly verified using
   the P-256 curve with a test vector.

2. test_ecdsa_verify_invalid_signature: Verifies that an invalid
   signature (with modified r component) is correctly rejected.

3. test_ecdsa_size_queries: Tests the bpf_sig_keysize(),
   bpf_sig_digestsize(), and bpf_sig_maxsize() kfuncs to ensure
   they return valid positive values for a P-256 ECDSA context.

4. test_ecdsa_on_hash_ctx: Tests that calling bpf_sig_verify on
   a hash context fails with -EINVAL due to type mismatch.

5. test_ecdsa_keysize_on_hash_ctx: Tests that calling bpf_sig_keysize
   on a hash context fails with -EINVAL due to type mismatch.

6. test_ecdsa_zero_len_msg: Tests that zero-length message is rejected.

7. test_ecdsa_zero_len_sig: Tests that zero-length signature is rejected.

The test uses the p1363(ecdsa-nist-p256) algorithm with a known
NIST P-256 test vector for reliable and reproducible testing.

Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 MAINTAINERS                                   |   2 +
 .../selftests/bpf/prog_tests/sig_verify.c     | 163 ++++++++++
 .../selftests/bpf/progs/crypto_common.h       |   6 +
 .../testing/selftests/bpf/progs/sig_verify.c  | 286 ++++++++++++++++++
 4 files changed, 457 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/sig_verify.c
 create mode 100644 tools/testing/selftests/bpf/progs/sig_verify.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d23ea38b606f..e297cc18c5f6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4719,7 +4719,9 @@ F:	crypto/bpf_crypto_skcipher.c
 F:	include/linux/bpf_crypto.h
 F:	kernel/bpf/crypto.c
 F:	tools/testing/selftests/bpf/prog_tests/crypto_hash.c
+F:	tools/testing/selftests/bpf/prog_tests/sig_verify.c
 F:	tools/testing/selftests/bpf/progs/crypto_hash.c
+F:	tools/testing/selftests/bpf/progs/sig_verify.c
 
 BPF [DOCUMENTATION] (Related to Standardization)
 R:	David Vernet <void@manifault.com>
diff --git a/tools/testing/selftests/bpf/prog_tests/sig_verify.c b/tools/testing/selftests/bpf/prog_tests/sig_verify.c
new file mode 100644
index 000000000000..f682fc3c8595
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/sig_verify.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include <test_progs.h>
+#include "sig_verify.skel.h"
+
+static void test_ecdsa_verify_valid_signature(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_verify_valid);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_verify_valid");
+	ASSERT_EQ(skel->data->ctx_create_status, 0, "ctx_create_status");
+	ASSERT_EQ(skel->data->verify_result, 0, "verify_valid_signature");
+
+	sig_verify__destroy(skel);
+}
+
+static void test_ecdsa_verify_invalid_signature(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_verify_invalid);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_verify_invalid");
+	ASSERT_NEQ(skel->data->verify_invalid_result, 0, "verify_invalid_signature_rejected");
+
+	sig_verify__destroy(skel);
+}
+
+static void test_ecdsa_size_queries(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_size_queries);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_size_queries");
+	ASSERT_EQ(skel->data->ctx_create_status, 0, "ctx_create_status");
+	/* P-256 key size is 256 bits = 32 bytes */
+	ASSERT_GT(skel->data->keysize_result, 0, "keysize_positive");
+	/* P-256 digest size is 32 bytes (SHA-256) */
+	ASSERT_GT(skel->data->digestsize_result, 0, "digestsize_positive");
+	/* P-256 max signature size is 64 bytes (r||s format) */
+	ASSERT_GT(skel->data->maxsize_result, 0, "maxsize_positive");
+
+	sig_verify__destroy(skel);
+}
+
+static void test_ecdsa_on_hash_ctx(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_on_hash_ctx);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_on_hash_ctx");
+	ASSERT_EQ(skel->data->ecdsa_on_hash_ctx_status, 0, "ecdsa_on_hash_ctx_rejected");
+
+	sig_verify__destroy(skel);
+}
+
+static void test_ecdsa_keysize_on_hash_ctx(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_keysize_on_hash_ctx);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_keysize_on_hash_ctx");
+	ASSERT_EQ(skel->data->ecdsa_keysize_on_hash_status, 0, "ecdsa_keysize_on_hash_rejected");
+
+	sig_verify__destroy(skel);
+}
+
+static void test_ecdsa_zero_len_msg(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_zero_len_msg);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_zero_len_msg");
+	ASSERT_EQ(skel->data->ecdsa_zero_msg_status, 0, "zero_len_msg_rejected");
+
+	sig_verify__destroy(skel);
+}
+
+static void test_ecdsa_zero_len_sig(void)
+{
+	struct sig_verify *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = sig_verify__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "sig_verify__open_and_load"))
+		return;
+
+	prog_fd = bpf_program__fd(skel->progs.test_ecdsa_zero_len_sig);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_ecdsa_zero_len_sig");
+	ASSERT_EQ(skel->data->ecdsa_zero_sig_status, 0, "zero_len_sig_rejected");
+
+	sig_verify__destroy(skel);
+}
+
+void test_sig_verify(void)
+{
+	if (test__start_subtest("verify_valid_signature"))
+		test_ecdsa_verify_valid_signature();
+	if (test__start_subtest("verify_invalid_signature"))
+		test_ecdsa_verify_invalid_signature();
+	if (test__start_subtest("size_queries"))
+		test_ecdsa_size_queries();
+	if (test__start_subtest("ecdsa_on_hash_ctx"))
+		test_ecdsa_on_hash_ctx();
+	if (test__start_subtest("ecdsa_keysize_on_hash_ctx"))
+		test_ecdsa_keysize_on_hash_ctx();
+	if (test__start_subtest("zero_len_msg"))
+		test_ecdsa_zero_len_msg();
+	if (test__start_subtest("zero_len_sig"))
+		test_ecdsa_zero_len_sig();
+}
diff --git a/tools/testing/selftests/bpf/progs/crypto_common.h b/tools/testing/selftests/bpf/progs/crypto_common.h
index 2f04f08f890b..3849083f2d23 100644
--- a/tools/testing/selftests/bpf/progs/crypto_common.h
+++ b/tools/testing/selftests/bpf/progs/crypto_common.h
@@ -17,6 +17,12 @@ int bpf_crypto_decrypt(struct bpf_crypto_ctx *ctx, const struct bpf_dynptr *src,
 		       const struct bpf_dynptr *dst, const struct bpf_dynptr *iv) __ksym;
 int bpf_crypto_hash(struct bpf_crypto_ctx *ctx, const struct bpf_dynptr *data,
 		    const struct bpf_dynptr *out) __ksym;
+int bpf_sig_verify(struct bpf_crypto_ctx *ctx,
+		     const struct bpf_dynptr *message,
+		     const struct bpf_dynptr *signature) __ksym;
+int bpf_sig_keysize(struct bpf_crypto_ctx *ctx) __ksym;
+int bpf_sig_digestsize(struct bpf_crypto_ctx *ctx) __ksym;
+int bpf_sig_maxsize(struct bpf_crypto_ctx *ctx) __ksym;
 
 struct __crypto_ctx_value {
 	struct bpf_crypto_ctx __kptr * ctx;
diff --git a/tools/testing/selftests/bpf/progs/sig_verify.c b/tools/testing/selftests/bpf/progs/sig_verify.c
new file mode 100644
index 000000000000..27488404444d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sig_verify.c
@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "crypto_common.h"
+
+/* NIST P-256 test vector
+ * This is a known valid ECDSA signature for testing purposes
+ */
+
+/* Public key in uncompressed format: 0x04 || x || y (65 bytes) */
+unsigned char pubkey_p256[65] = {
+	0x04, /* Uncompressed point indicator */
+	/* X coordinate (32 bytes) */
+	0x60, 0xfe, 0xd4, 0xba, 0x25, 0x5a, 0x9d, 0x31,
+	0xc9, 0x61, 0xeb, 0x74, 0xc6, 0x35, 0x6d, 0x68,
+	0xc0, 0x49, 0xb8, 0x92, 0x3b, 0x61, 0xfa, 0x6c,
+	0xe6, 0x69, 0x62, 0x2e, 0x60, 0xf2, 0x9f, 0xb6,
+	/* Y coordinate (32 bytes) */
+	0x79, 0x03, 0xfe, 0x10, 0x08, 0xb8, 0xbc, 0x99,
+	0xa4, 0x1a, 0xe9, 0xe9, 0x56, 0x28, 0xbc, 0x64,
+	0xf2, 0xf1, 0xb2, 0x0c, 0x2d, 0x7e, 0x9f, 0x51,
+	0x77, 0xa3, 0xc2, 0x94, 0xd4, 0x46, 0x22, 0x99
+};
+
+/* Message hash (32 bytes) - SHA-256 of "sample" */
+unsigned char message_hash[32] = {
+	0xaf, 0x2b, 0xdb, 0xe1, 0xaa, 0x9b, 0x6e, 0xc1,
+	0xe2, 0xad, 0xe1, 0xd6, 0x94, 0xf4, 0x1f, 0xc7,
+	0x1a, 0x83, 0x1d, 0x02, 0x68, 0xe9, 0x89, 0x15,
+	0x62, 0x11, 0x3d, 0x8a, 0x62, 0xad, 0xd1, 0xbf
+};
+
+/* Valid signature r || s (64 bytes) */
+unsigned char valid_signature[64] = {
+	/* r component (32 bytes) */
+	0xef, 0xd4, 0x8b, 0x2a, 0xac, 0xb6, 0xa8, 0xfd,
+	0x11, 0x40, 0xdd, 0x9c, 0xd4, 0x5e, 0x81, 0xd6,
+	0x9d, 0x2c, 0x87, 0x7b, 0x56, 0xaa, 0xf9, 0x91,
+	0xc3, 0x4d, 0x0e, 0xa8, 0x4e, 0xaf, 0x37, 0x16,
+	/* s component (32 bytes) */
+	0xf7, 0xcb, 0x1c, 0x94, 0x2d, 0x65, 0x7c, 0x41,
+	0xd4, 0x36, 0xc7, 0xa1, 0xb6, 0xe2, 0x9f, 0x65,
+	0xf3, 0xe9, 0x00, 0xdb, 0xb9, 0xaf, 0xf4, 0x06,
+	0x4d, 0xc4, 0xab, 0x2f, 0x84, 0x3a, 0xcd, 0xa8
+};
+
+/* Invalid signature (modified r component) for negative test */
+unsigned char invalid_signature[64] = {
+	/* r component (32 bytes) - first byte modified */
+	0xff, 0xd4, 0x8b, 0x2a, 0xac, 0xb6, 0xa8, 0xfd,
+	0x11, 0x40, 0xdd, 0x9c, 0xd4, 0x5e, 0x81, 0xd6,
+	0x9d, 0x2c, 0x87, 0x7b, 0x56, 0xaa, 0xf9, 0x91,
+	0xc3, 0x4d, 0x0e, 0xa8, 0x4e, 0xaf, 0x37, 0x16,
+	/* s component (32 bytes) */
+	0xf7, 0xcb, 0x1c, 0x94, 0x2d, 0x65, 0x7c, 0x41,
+	0xd4, 0x36, 0xc7, 0xa1, 0xb6, 0xe2, 0x9f, 0x65,
+	0xf3, 0xe9, 0x00, 0xdb, 0xb9, 0xaf, 0xf4, 0x06,
+	0x4d, 0xc4, 0xab, 0x2f, 0x84, 0x3a, 0xcd, 0xa8
+};
+
+/* Test results */
+int verify_result = -1;
+int verify_invalid_result = -1;
+int ctx_create_status = -1;
+int keysize_result = -1;
+int digestsize_result = -1;
+int maxsize_result = -1;
+int ecdsa_on_hash_ctx_status = -1;
+int ecdsa_keysize_on_hash_status = -1;
+int ecdsa_zero_msg_status = -1;
+int ecdsa_zero_sig_status = -1;
+
+SEC("syscall")
+int test_ecdsa_verify_valid(void *ctx)
+{
+	struct bpf_crypto_ctx *ecdsa_ctx;
+	struct bpf_crypto_params params = {
+		.type = "sig",
+		.algo = "p1363(ecdsa-nist-p256)",
+		.key_len = sizeof(pubkey_p256),
+	};
+	struct bpf_dynptr msg_ptr, sig_ptr;
+	int err = 0;
+
+	__builtin_memcpy(params.key, pubkey_p256, sizeof(pubkey_p256));
+
+	ecdsa_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!ecdsa_ctx) {
+		ctx_create_status = err;
+		return 0;
+	}
+	ctx_create_status = 0;
+
+	bpf_dynptr_from_mem(message_hash, sizeof(message_hash), 0, &msg_ptr);
+	bpf_dynptr_from_mem(valid_signature, sizeof(valid_signature), 0, &sig_ptr);
+
+	verify_result = bpf_sig_verify(ecdsa_ctx, &msg_ptr, &sig_ptr);
+
+	bpf_crypto_ctx_release(ecdsa_ctx);
+
+	return 0;
+}
+
+SEC("syscall")
+int test_ecdsa_verify_invalid(void *ctx)
+{
+	struct bpf_crypto_ctx *ecdsa_ctx;
+	struct bpf_crypto_params params = {
+		.type = "sig",
+		.algo = "p1363(ecdsa-nist-p256)",
+		.key_len = sizeof(pubkey_p256),
+	};
+	struct bpf_dynptr msg_ptr, sig_ptr;
+	int err = 0;
+
+	__builtin_memcpy(params.key, pubkey_p256, sizeof(pubkey_p256));
+
+	ecdsa_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!ecdsa_ctx)
+		return 0;
+
+	bpf_dynptr_from_mem(message_hash, sizeof(message_hash), 0, &msg_ptr);
+	bpf_dynptr_from_mem(invalid_signature, sizeof(invalid_signature), 0, &sig_ptr);
+
+	verify_invalid_result = bpf_sig_verify(ecdsa_ctx, &msg_ptr, &sig_ptr);
+
+	bpf_crypto_ctx_release(ecdsa_ctx);
+
+	return 0;
+}
+
+SEC("syscall")
+int test_ecdsa_size_queries(void *ctx)
+{
+	struct bpf_crypto_ctx *ecdsa_ctx;
+	struct bpf_crypto_params params = {
+		.type = "sig",
+		.algo = "p1363(ecdsa-nist-p256)",
+		.key_len = sizeof(pubkey_p256),
+	};
+	int err = 0;
+
+	__builtin_memcpy(params.key, pubkey_p256, sizeof(pubkey_p256));
+
+	ecdsa_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!ecdsa_ctx) {
+		ctx_create_status = err;
+		return 0;
+	}
+	ctx_create_status = 0;
+
+	keysize_result = bpf_sig_keysize(ecdsa_ctx);
+	digestsize_result = bpf_sig_digestsize(ecdsa_ctx);
+	maxsize_result = bpf_sig_maxsize(ecdsa_ctx);
+
+	bpf_crypto_ctx_release(ecdsa_ctx);
+
+	return 0;
+}
+
+/* Test that calling bpf_sig_verify on hash context fails with type mismatch */
+SEC("syscall")
+int test_ecdsa_on_hash_ctx(void *ctx)
+{
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha256",
+		.key_len = 0,
+	};
+	struct bpf_dynptr msg_ptr, sig_ptr;
+	int err = 0;
+	int ret;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		ecdsa_on_hash_ctx_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(message_hash, sizeof(message_hash), 0, &msg_ptr);
+	bpf_dynptr_from_mem(valid_signature, sizeof(valid_signature), 0, &sig_ptr);
+
+	ret = bpf_sig_verify(hash_ctx, &msg_ptr, &sig_ptr);
+	/* Expected: should fail with -EINVAL (-22) due to type_id mismatch */
+	ecdsa_on_hash_ctx_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+/* Test that calling bpf_sig_keysize on hash context fails with type mismatch */
+SEC("syscall")
+int test_ecdsa_keysize_on_hash_ctx(void *ctx)
+{
+	struct bpf_crypto_ctx *hash_ctx;
+	struct bpf_crypto_params params = {
+		.type = "hash",
+		.algo = "sha256",
+		.key_len = 0,
+	};
+	int err = 0;
+	int ret;
+
+	hash_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!hash_ctx) {
+		ecdsa_keysize_on_hash_status = err;
+		return 0;
+	}
+
+	ret = bpf_sig_keysize(hash_ctx);
+	/* Expected: should fail with -EINVAL (-22) due to type_id mismatch */
+	ecdsa_keysize_on_hash_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(hash_ctx);
+	return 0;
+}
+
+/* Test that bpf_sig_verify with zero-length message fails */
+SEC("syscall")
+int test_ecdsa_zero_len_msg(void *ctx)
+{
+	struct bpf_crypto_ctx *ecdsa_ctx;
+	struct bpf_crypto_params params = {
+		.type = "sig",
+		.algo = "p1363(ecdsa-nist-p256)",
+		.key_len = sizeof(pubkey_p256),
+	};
+	struct bpf_dynptr msg_ptr, sig_ptr;
+	int err = 0;
+	int ret;
+
+	__builtin_memcpy(params.key, pubkey_p256, sizeof(pubkey_p256));
+
+	ecdsa_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!ecdsa_ctx) {
+		ecdsa_zero_msg_status = err;
+		return 0;
+	}
+
+	/* Zero-length message */
+	bpf_dynptr_from_mem(message_hash, 0, 0, &msg_ptr);
+	bpf_dynptr_from_mem(valid_signature, sizeof(valid_signature), 0, &sig_ptr);
+
+	ret = bpf_sig_verify(ecdsa_ctx, &msg_ptr, &sig_ptr);
+	/* Expected: should fail with -EINVAL (-22) */
+	ecdsa_zero_msg_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(ecdsa_ctx);
+	return 0;
+}
+
+/* Test that bpf_sig_verify with zero-length signature fails */
+SEC("syscall")
+int test_ecdsa_zero_len_sig(void *ctx)
+{
+	struct bpf_crypto_ctx *ecdsa_ctx;
+	struct bpf_crypto_params params = {
+		.type = "sig",
+		.algo = "p1363(ecdsa-nist-p256)",
+		.key_len = sizeof(pubkey_p256),
+	};
+	struct bpf_dynptr msg_ptr, sig_ptr;
+	int err = 0;
+	int ret;
+
+	__builtin_memcpy(params.key, pubkey_p256, sizeof(pubkey_p256));
+
+	ecdsa_ctx = bpf_crypto_ctx_create(&params, sizeof(params), &err);
+	if (!ecdsa_ctx) {
+		ecdsa_zero_sig_status = err;
+		return 0;
+	}
+
+	bpf_dynptr_from_mem(message_hash, sizeof(message_hash), 0, &msg_ptr);
+	/* Zero-length signature */
+	bpf_dynptr_from_mem(valid_signature, 0, 0, &sig_ptr);
+
+	ret = bpf_sig_verify(ecdsa_ctx, &msg_ptr, &sig_ptr);
+	/* Expected: should fail with -EINVAL (-22) */
+	ecdsa_zero_sig_status = (ret == -22) ? 0 : ret;
+	bpf_crypto_ctx_release(ecdsa_ctx);
+	return 0;
+}
+
+char __license[] SEC("license") = "GPL";
-- 
2.52.0

Re: [PATCH bpf-next v5 2/7] crypto: Add BPF hash algorithm type registration module

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 1799 bytes --]

> diff --git a/crypto/bpf_crypto_shash.c b/crypto/bpf_crypto_shash.c
> new file mode 100644
> index 000000000000..6e9b0d757ec9
> --- /dev/null
> +++ b/crypto/bpf_crypto_shash.c

[ ... ]

> +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,
> +	.type_id	= BPF_CRYPTO_TYPE_HASH,
> +	.name		= "hash",
> +};

Can this cause a NULL pointer dereference when a BPF program calls
bpf_crypto_ctx_create() with type="hash"?

The bpf_crypto_ctx_create() function in kernel/bpf/crypto.c unconditionally
calls type->setkey(), type->ivsize(), and type->statesize():

    *err = type->setkey(ctx->tfm, params->key, params->key_len);
    ...
    ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);

But bpf_crypto_shash_type does not implement these callbacks, leaving them
as NULL.

Note: This appears to be fixed later in the series by commit 76d771a64b50
("bpf: Add hash kfunc for cryptographic hashing") which adds NULL checks
before calling these function pointers. Should this commit be squashed
with 76d771a64b50 to ensure each patch in the series is bisectable without
introducing crashes?

> +module_init(bpf_crypto_shash_init);
> +module_exit(bpf_crypto_shash_exit);
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Hash algorithm support for BPF");


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21183820118

Re: [PATCH bpf-next v5 3/7] crypto: Add BPF signature algorithm type registration module

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 1513 bytes --]

> diff --git a/crypto/bpf_crypto_sig.c b/crypto/bpf_crypto_sig.c
> new file mode 100644
> index 000000000000..1d6521a066be
> --- /dev/null
> +++ b/crypto/bpf_crypto_sig.c

[ ... ]

> +static const struct bpf_crypto_type bpf_crypto_sig_type = {
> +	.alloc_tfm	= bpf_crypto_sig_alloc_tfm,
> +	.free_tfm	= bpf_crypto_sig_free_tfm,
> +	.has_algo	= bpf_crypto_sig_has_algo,
> +	.get_flags	= bpf_crypto_sig_get_flags,
> +	.setkey		= bpf_crypto_sig_setkey,
> +	.verify		= bpf_crypto_sig_verify,
> +	.owner		= THIS_MODULE,
> +	.type_id	= BPF_CRYPTO_TYPE_SIG,
> +	.name		= "sig",
> +};

The bpf_crypto_sig_type struct does not set .ivsize or .statesize callbacks.
In bpf_crypto_ctx_create() in kernel/bpf/crypto.c, there is an unconditional
call:

    ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);

If a BPF program creates a crypto context with type="sig", this will call
NULL function pointers and crash the kernel.

I see this is fixed later in the series by commit 76d771a64b50 ("bpf: Add
hash kfunc for cryptographic hashing") which adds NULL checks:

    if (type->ivsize && type->statesize)
        ctx->siv_len = type->ivsize(ctx->tfm) + type->statesize(ctx->tfm);

Should this fix be folded into this commit to avoid the intermediate crash?

[ ... ]


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21183820118