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authorVitaly Chikunov <vt@altlinux.org>2019-04-11 18:51:15 +0300
committerHerbert Xu <herbert@gondor.apana.org.au>2019-04-18 22:15:02 +0800
commitc7381b01287240abe942a081729203e26782d981 (patch)
treef70bd59c5b8b110b9116d1660d5fe03033ed3596 /include/crypto/akcipher.h
parent3ecc97259934489e7e03cbeb1d70f6a23cccb3ae (diff)
downloadlinux-stericsson-c7381b01287240abe942a081729203e26782d981.tar.gz
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 <dhowells@redhat.com> Cc: keyrings@vger.kernel.org Signed-off-by: Vitaly Chikunov <vt@altlinux.org> Reviewed-by: Denis Kenzior <denkenz@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'include/crypto/akcipher.h')
-rw-r--r--include/crypto/akcipher.h36
1 files changed, 23 insertions, 13 deletions
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)
{