Add evp_keymgmt_export_to_provider(), for key transfer between providers

This function is used to transport private key materia from whatever
is already attached to the EVP_PKEY to the new provider, using key
data export and import functionality.

If a legacy lower level key has been assigned to the EVP_PKEY, we use
its data to create a provider side key, and thereby have a bridge
between old style public key types and the EVP_PKEY on providers.

If successful, this function returns a reference to the appropriate
provider side data for the key.

This can be used by any operation that wants to use this key.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9312)

2 files changed, 16 insertions, 0 deletions

diff --git a/crypto/include/internal/asn1_int.h b/crypto/include/internal/asn1_int.h
index 1f62063b08..674fa704a1 100644
--- a/crypto/include/internal/asn1_int.h
+++ b/crypto/include/internal/asn1_int.h
@@ -63,6 +63,14 @@ struct evp_pkey_asn1_method_st {
     int (*set_pub_key) (EVP_PKEY *pk, const unsigned char *pub, size_t len);
     int (*get_priv_key) (const EVP_PKEY *pk, unsigned char *priv, size_t *len);
     int (*get_pub_key) (const EVP_PKEY *pk, unsigned char *pub, size_t *len);
+
+    /*
+     * TODO: Make sure these functions are defined for key types that are
+     * implemented in providers.
+     */
+    /* Exports to providers */
+    size_t (*dirty_cnt) (const EVP_PKEY *pk);
+    void *(*export_to) (const EVP_PKEY *pk, EVP_KEYMGMT *keymgmt);
 } /* EVP_PKEY_ASN1_METHOD */ ;
 
 DEFINE_STACK_OF_CONST(EVP_PKEY_ASN1_METHOD)
diff --git a/crypto/include/internal/evp_int.h b/crypto/include/internal/evp_int.h
index 359d561342..ff9b6e545b 100644
--- a/crypto/include/internal/evp_int.h
+++ b/crypto/include/internal/evp_int.h
@@ -545,6 +545,11 @@ struct evp_pkey_st {
         EVP_KEYMGMT *keymgmt;
         void *provkey;
     } pkeys[10];
+    /*
+     * If there is a legacy key assigned to this structure, we keep
+     * a copy of that key's dirty count.
+     */
+    size_t dirty_cnt_copy;
 } /* EVP_PKEY */ ;
 
 
@@ -555,6 +560,9 @@ void openssl_add_all_kdfs_int(void);
 void evp_cleanup_int(void);
 void evp_app_cleanup_int(void);
 
+void *evp_keymgmt_export_to_provider(EVP_PKEY *pk, EVP_KEYMGMT *keymgmt);
+
+
 /* Pulling defines out of C source files */
 
 #define EVP_RC4_KEY_SIZE 16