From c7381b01287240abe942a081729203e26782d981 Mon Sep 17 00:00:00 2001 From: Vitaly Chikunov Date: Thu, 11 Apr 2019 18:51:15 +0300 Subject: crypto: akcipher - new verify API for public key algorithms Previous akcipher .verify() just `decrypts' (using RSA encrypt which is using public key) signature to uncover message hash, which was then compared in upper level public_key_verify_signature() with the expected hash value, which itself was never passed into verify(). This approach was incompatible with EC-DSA family of algorithms, because, to verify a signature EC-DSA algorithm also needs a hash value as input; then it's used (together with a signature divided into halves `r||s') to produce a witness value, which is then compared with `r' to determine if the signature is correct. Thus, for EC-DSA, nor requirements of .verify() itself, nor its output expectations in public_key_verify_signature() wasn't sufficient. Make improved .verify() call which gets hash value as input and produce complete signature check without any output besides status. Now for the top level verification only crypto_akcipher_verify() needs to be called and its return value inspected. Make sure that `digest' is in kmalloc'd memory (in place of `output`) in {public,tpm}_key_verify_signature() as insisted by Herbert Xu, and will be changed in the following commit. Cc: David Howells Cc: keyrings@vger.kernel.org Signed-off-by: Vitaly Chikunov Reviewed-by: Denis Kenzior Signed-off-by: Herbert Xu --- include/crypto/akcipher.h | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-) (limited to 'include/crypto') diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h index 2d690494568c..2d26939fff51 100644 --- a/include/crypto/akcipher.h +++ b/include/crypto/akcipher.h @@ -19,14 +19,20 @@ * * @base: Common attributes for async crypto requests * @src: Source data - * @dst: Destination data + * For verify op this is signature + digest, in that case + * total size of @src is @src_len + @dst_len. + * @dst: Destination data (Should be NULL for verify op) * @src_len: Size of the input buffer - * @dst_len: Size of the output buffer. It needs to be at least - * as big as the expected result depending on the operation + * For verify op it's size of signature part of @src, this part + * is supposed to be operated by cipher. + * @dst_len: Size of @dst buffer (for all ops except verify). + * It needs to be at least as big as the expected result + * depending on the operation. * After operation it will be updated with the actual size of the * result. * In case of error where the dst sgl size was insufficient, * it will be updated to the size required for the operation. + * For verify op this is size of digest part in @src. * @__ctx: Start of private context data */ struct akcipher_request { @@ -55,10 +61,9 @@ struct crypto_akcipher { * algorithm. In case of error, where the dst_len was insufficient, * the req->dst_len will be updated to the size required for the * operation - * @verify: Function performs a sign operation as defined by public key - * algorithm. In case of error, where the dst_len was insufficient, - * the req->dst_len will be updated to the size required for the - * operation + * @verify: Function performs a complete verify operation as defined by + * public key algorithm, returning verification status. Requires + * digest value as input parameter. * @encrypt: Function performs an encrypt operation as defined by public key * algorithm. In case of error, where the dst_len was insufficient, * the req->dst_len will be updated to the size required for the @@ -238,9 +243,10 @@ static inline void akcipher_request_set_callback(struct akcipher_request *req, * * @req: public key request * @src: ptr to input scatter list - * @dst: ptr to output scatter list + * @dst: ptr to output scatter list or NULL for verify op * @src_len: size of the src input scatter list to be processed - * @dst_len: size of the dst output scatter list + * @dst_len: size of the dst output scatter list or size of signature + * portion in @src for verify op */ static inline void akcipher_request_set_crypt(struct akcipher_request *req, struct scatterlist *src, @@ -343,14 +349,18 @@ static inline int crypto_akcipher_sign(struct akcipher_request *req) } /** - * crypto_akcipher_verify() - Invoke public key verify operation + * crypto_akcipher_verify() - Invoke public key signature verification * - * Function invokes the specific public key verify operation for a given - * public key algorithm + * Function invokes the specific public key signature verification operation + * for a given public key algorithm. * * @req: asymmetric key request * - * Return: zero on success; error code in case of error + * Note: req->dst should be NULL, req->src should point to SG of size + * (req->src_size + req->dst_size), containing signature (of req->src_size + * length) with appended digest (of req->dst_size length). + * + * Return: zero on verification success; error code in case of error. */ static inline int crypto_akcipher_verify(struct akcipher_request *req) { -- cgit