crypto: kpp - constify buffer passed to crypto_kpp_set_secret()

Constify the buffer passed to crypto_kpp_set_secret() and
kpp_alg.set_secret, since it is never modified.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/dh.c

@@ -79,7 +79,8 @@ static int dh_set_params(struct dh_ctx *ctx, struct dh *params)
 	return 0;
 }
 
-static int dh_set_secret(struct crypto_kpp *tfm, void *buf, unsigned int len)
+static int dh_set_secret(struct crypto_kpp *tfm, const void *buf,
+			 unsigned int len)
 {
 	struct dh_ctx *ctx = dh_get_ctx(tfm);
 	struct dh params;

crypto/ecdh.c

@@ -38,7 +38,8 @@ static unsigned int ecdh_supported_curve(unsigned int curve_id)
 	}
 }
 
-static int ecdh_set_secret(struct crypto_kpp *tfm, void *buf, unsigned int len)
+static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
+			   unsigned int len)
 {
 	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
 	struct ecdh params;

drivers/crypto/qat/qat_common/qat_asym_algs.c

@@ -491,7 +491,7 @@ static void qat_dh_clear_ctx(struct device *dev, struct qat_dh_ctx *ctx)
 	ctx->g2 = false;
 }
 
-static int qat_dh_set_secret(struct crypto_kpp *tfm, void *buf,
+static int qat_dh_set_secret(struct crypto_kpp *tfm, const void *buf,
 			     unsigned int len)
 {
 	struct qat_dh_ctx *ctx = kpp_tfm_ctx(tfm);

include/crypto/kpp.h

@@ -74,7 +74,7 @@ struct crypto_kpp {
  * @base:		Common crypto API algorithm data structure
  */
 struct kpp_alg {
-	int (*set_secret)(struct crypto_kpp *tfm, void *buffer,
+	int (*set_secret)(struct crypto_kpp *tfm, const void *buffer,
 			  unsigned int len);
 	int (*generate_public_key)(struct kpp_request *req);
 	int (*compute_shared_secret)(struct kpp_request *req);
@@ -273,8 +273,8 @@ struct kpp_secret {
  *
  * Return: zero on success; error code in case of error
  */
-static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm, void *buffer,
-					unsigned int len)
+static inline int crypto_kpp_set_secret(struct crypto_kpp *tfm,
+					const void *buffer, unsigned int len)
 {
 	struct kpp_alg *alg = crypto_kpp_alg(tfm);