lib/crypto: sha2: Add hmac_sha*_init_usingrawkey()

While the HMAC library functions support both incremental and one-shot
computation and both prepared and raw keys, the combination of raw key
+ incremental was missing.  It turns out that several potential users of
the HMAC library functions (tpm2-sessions.c, smb2transport.c,
trusted_tpm1.c) want exactly that.

Therefore, add the missing functions hmac_sha*_init_usingrawkey().

Implement them in an optimized way that directly initializes the HMAC
context without a separate key preparation step.

Reimplement the one-shot raw key functions hmac_sha*_usingrawkey() on
top of the new functions, which makes them a bit more efficient.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250711215844.41715-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/include/crypto/sha2.h b/include/crypto/sha2.h
index e0a08f6addd0..15e461e568cc 100644
--- a/include/crypto/sha2.h
+++ b/include/crypto/sha2.h
@@ -248,6 +248,21 @@ static inline void hmac_sha224_init(struct hmac_sha224_ctx *ctx,
 }
 
 /**
+ * hmac_sha224_init_usingrawkey() - Initialize an HMAC-SHA224 context for a new
+ *				    message, using a raw key
+ * @ctx: (output) the HMAC context to initialize
+ * @raw_key: the raw HMAC-SHA224 key
+ * @raw_key_len: the key length in bytes.  All key lengths are supported.
+ *
+ * If you don't need incremental computation, consider hmac_sha224_usingrawkey()
+ * instead.
+ *
+ * Context: Any context.
+ */
+void hmac_sha224_init_usingrawkey(struct hmac_sha224_ctx *ctx,
+				  const u8 *raw_key, size_t raw_key_len);
+
+/**
  * hmac_sha224_update() - Update an HMAC-SHA224 context with message data
  * @ctx: the HMAC context to update; must have been initialized
  * @data: the message data
@@ -406,6 +421,21 @@ static inline void hmac_sha256_init(struct hmac_sha256_ctx *ctx,
 }
 
 /**
+ * hmac_sha256_init_usingrawkey() - Initialize an HMAC-SHA256 context for a new
+ *				    message, using a raw key
+ * @ctx: (output) the HMAC context to initialize
+ * @raw_key: the raw HMAC-SHA256 key
+ * @raw_key_len: the key length in bytes.  All key lengths are supported.
+ *
+ * If you don't need incremental computation, consider hmac_sha256_usingrawkey()
+ * instead.
+ *
+ * Context: Any context.
+ */
+void hmac_sha256_init_usingrawkey(struct hmac_sha256_ctx *ctx,
+				  const u8 *raw_key, size_t raw_key_len);
+
+/**
  * hmac_sha256_update() - Update an HMAC-SHA256 context with message data
  * @ctx: the HMAC context to update; must have been initialized
  * @data: the message data
@@ -598,6 +628,21 @@ static inline void hmac_sha384_init(struct hmac_sha384_ctx *ctx,
 }
 
 /**
+ * hmac_sha384_init_usingrawkey() - Initialize an HMAC-SHA384 context for a new
+ *				    message, using a raw key
+ * @ctx: (output) the HMAC context to initialize
+ * @raw_key: the raw HMAC-SHA384 key
+ * @raw_key_len: the key length in bytes.  All key lengths are supported.
+ *
+ * If you don't need incremental computation, consider hmac_sha384_usingrawkey()
+ * instead.
+ *
+ * Context: Any context.
+ */
+void hmac_sha384_init_usingrawkey(struct hmac_sha384_ctx *ctx,
+				  const u8 *raw_key, size_t raw_key_len);
+
+/**
  * hmac_sha384_update() - Update an HMAC-SHA384 context with message data
  * @ctx: the HMAC context to update; must have been initialized
  * @data: the message data
@@ -756,6 +801,21 @@ static inline void hmac_sha512_init(struct hmac_sha512_ctx *ctx,
 }
 
 /**
+ * hmac_sha512_init_usingrawkey() - Initialize an HMAC-SHA512 context for a new
+ *				    message, using a raw key
+ * @ctx: (output) the HMAC context to initialize
+ * @raw_key: the raw HMAC-SHA512 key
+ * @raw_key_len: the key length in bytes.  All key lengths are supported.
+ *
+ * If you don't need incremental computation, consider hmac_sha512_usingrawkey()
+ * instead.
+ *
+ * Context: Any context.
+ */
+void hmac_sha512_init_usingrawkey(struct hmac_sha512_ctx *ctx,
+				  const u8 *raw_key, size_t raw_key_len);
+
+/**
  * hmac_sha512_update() - Update an HMAC-SHA512 context with message data
  * @ctx: the HMAC context to update; must have been initialized
  * @data: the message data