Introduce mbedtls_pk_restart_ctx and use it

The fact that you needed to pass a pointer to mbedtls_ecdsa_restart_ctx (or
that you needed to know the key type of the PK context) was a breach of
abstraction.

Change the API (and callers) now, and the implementation will be changed in
the next commit.

include/mbedtls/pk.h

@@ -129,6 +129,19 @@ typedef struct
     void *                      pk_ctx;  /**< Underlying public key context  */
 } mbedtls_pk_context;
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+/**
+ * \brief           Context for resuming operations
+ */
+typedef struct
+{
+    mbedtls_ecdsa_restart_ctx ecdsa;    /* temporary */
+} mbedtls_pk_restart_ctx;
+#else
+/* Now we can declare functions that take a pointer to that */
+typedef void mbedtls_pk_restart_ctx;
+#endif
+
 #if defined(MBEDTLS_RSA_C)
 /**
  * Quick access to an RSA context inside a PK context.
@@ -188,6 +201,18 @@ void mbedtls_pk_init( mbedtls_pk_context *ctx );
  */
 void mbedtls_pk_free( mbedtls_pk_context *ctx );
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+/**
+ * \brief           Initialize a restart context
+ */
+void mbedtls_pk_restart_init( mbedtls_pk_restart_ctx *ctx );
+
+/**
+ * \brief           Free the components of a restart context
+ */
+void mbedtls_pk_restart_free( mbedtls_pk_restart_ctx *ctx );
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
 /**
  * \brief           Initialize a PK context with the information given
  *                  and allocates the type-specific PK subcontext.
@@ -298,8 +323,7 @@ int mbedtls_pk_verify( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
  * \param hash_len  Hash length or 0 (see notes)
  * \param sig       Signature to verify
  * \param sig_len   Signature length
- * \param rs_ctx    Restart context: for ECC, must be NULL (no restart) or a
+ * \param rs_ctx    Restart context (NULL to disable restart)
- *                  pointer to a \c mbedtls_ecdsa_restart_ctx. Ignored for RSA.
  *
  * \return          See \c mbedtls_pk_verify(), or
  *                  MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
@@ -309,7 +333,7 @@ int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
                mbedtls_md_type_t md_alg,
                const unsigned char *hash, size_t hash_len,
                const unsigned char *sig, size_t sig_len,
-               void *rs_ctx );
+               mbedtls_pk_restart_ctx *rs_ctx );
 
 /**
  * \brief           Verify signature, with options.
@@ -390,8 +414,7 @@ int mbedtls_pk_sign( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
  * \param sig_len   Number of bytes written
  * \param f_rng     RNG function
  * \param p_rng     RNG parameter
- * \param rs_ctx    Restart context: for ECC, must be NULL (no restart) or a
+ * \param rs_ctx    Restart context (NULL to disable restart)
- *                  pointer to a \c mbedtls_ecdsa_restart_ctx. Ignored for RSA.
  *
  * \return          See \c mbedtls_pk_sign(), or
  *                  MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
@@ -402,7 +425,7 @@ int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
              const unsigned char *hash, size_t hash_len,
              unsigned char *sig, size_t *sig_len,
              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
-             void *rs_ctx );
+             mbedtls_pk_restart_ctx *rs_ctx );
 
 /**
  * \brief           Decrypt message (including padding if relevant).

include/mbedtls/x509_crt.h

@@ -172,7 +172,7 @@ typedef struct
 typedef struct
 {
     /* for check_signature() */
-    mbedtls_ecdsa_restart_ctx   ecdsa;
+    mbedtls_pk_restart_ctx pk;
 
     /* for find_parent_in() */
     mbedtls_x509_crt *parent; /* non-null iff parent_in in progress */

library/pk.c

@@ -73,6 +73,27 @@ void mbedtls_pk_free( mbedtls_pk_context *ctx )
     mbedtls_zeroize( ctx, sizeof( mbedtls_pk_context ) );
 }
 
+#if defined(MBEDTLS_ECP_RESTARTABLE)
+/*
+ * Initialize a restart context
+ */
+void mbedtls_pk_restart_init( mbedtls_pk_restart_ctx *ctx )
+{
+    mbedtls_ecdsa_restart_init( &ctx->ecdsa );
+}
+
+/*
+ * Free the components of a restart context
+ */
+void mbedtls_pk_restart_free( mbedtls_pk_restart_ctx *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    mbedtls_ecdsa_restart_free( &ctx->ecdsa );
+}
+#endif /* MBEDTLS_ECP_RESTARTABLE */
+
 /*
  * Get pk_info structure from type
  */
@@ -182,7 +203,7 @@ int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
                mbedtls_md_type_t md_alg,
                const unsigned char *hash, size_t hash_len,
                const unsigned char *sig, size_t sig_len,
-               void *rs_ctx )
+               mbedtls_pk_restart_ctx *rs_ctx )
 {
     if( ctx == NULL || ctx->pk_info == NULL ||
         pk_hashlen_helper( md_alg, &hash_len ) != 0 )
@@ -282,7 +303,7 @@ int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
              const unsigned char *hash, size_t hash_len,
              unsigned char *sig, size_t *sig_len,
              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
-             void *rs_ctx )
+             mbedtls_pk_restart_ctx *rs_ctx )
 {
     if( ctx == NULL || ctx->pk_info == NULL ||
         pk_hashlen_helper( md_alg, &hash_len ) != 0 )

library/ssl_cli.c

@@ -2615,7 +2615,7 @@ ske_process:
 
 #if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
         if( ssl->handshake->ecrs_enabled )
-            rs_ctx = &ssl->handshake->ecrs_ctx.ecdsa;
+            rs_ctx = &ssl->handshake->ecrs_ctx.pk;
 #endif
 
         if( ( ret = mbedtls_pk_verify_restartable(
@@ -3290,7 +3290,7 @@ keys_derived:
 
 #if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
     if( ssl->handshake->ecrs_enabled )
-        rs_ctx = &ssl->handshake->ecrs_ctx.ecdsa;
+        rs_ctx = &ssl->handshake->ecrs_ctx.pk;
 #endif
 
     if( ( ret = mbedtls_pk_sign_restartable( mbedtls_ssl_own_key( ssl ),

library/x509_crt.c

@@ -1875,7 +1875,7 @@ static int x509_crt_check_signature( const mbedtls_x509_crt *child,
     {
         return( mbedtls_pk_verify_restartable( &parent->pk,
                     child->sig_md, hash, mbedtls_md_get_size( md_info ),
-                    child->sig.p, child->sig.len, &rs_ctx->ecdsa ) );
+                    child->sig.p, child->sig.len, &rs_ctx->pk ) );
     }
 #else
     (void) rs_ctx;
@@ -2653,7 +2653,7 @@ void mbedtls_x509_crt_free( mbedtls_x509_crt *crt )
  */
 void mbedtls_x509_crt_restart_init( mbedtls_x509_crt_restart_ctx *ctx )
 {
-    mbedtls_ecdsa_restart_init( &ctx->ecdsa );
+    mbedtls_pk_restart_init( &ctx->pk );
 
     ctx->parent = NULL;
     ctx->fallback_parent = NULL;
@@ -2675,7 +2675,7 @@ void mbedtls_x509_crt_restart_free( mbedtls_x509_crt_restart_ctx *ctx )
     if( ctx == NULL )
         return;
 
-    mbedtls_ecdsa_restart_free( &ctx->ecdsa );
+    mbedtls_pk_restart_free( &ctx->pk );
 
     mbedtls_x509_crt_restart_init( ctx );
 }

tests/suites/test_suite_pk.function

@@ -127,12 +127,12 @@ void pk_rsa_verify_test_vec( char *message_hex_string, int digest,
     mbedtls_rsa_context *rsa;
     mbedtls_pk_context pk;
     int msg_len;
-    void *rs_ctx = NULL;
+    mbedtls_pk_restart_ctx *rs_ctx = NULL;
 #if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
-    mbedtls_ecdsa_restart_ctx ctx;
+    mbedtls_pk_restart_ctx ctx;
 
     rs_ctx = &ctx;
-    mbedtls_ecdsa_restart_init( rs_ctx );
+    mbedtls_pk_restart_init( rs_ctx );
     mbedtls_ecp_set_max_ops( 42 );
 #endif
 
@@ -163,7 +163,7 @@ void pk_rsa_verify_test_vec( char *message_hex_string, int digest,
 
 exit:
 #if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
-    mbedtls_ecdsa_restart_free( rs_ctx );
+    mbedtls_pk_restart_free( rs_ctx );
 #endif
     mbedtls_pk_free( &pk );
 }
@@ -274,7 +274,7 @@ void pk_sign_verify_restart( int pk_type, int grp_id, char *d_str,
                               int max_ops, int min_restart, int max_restart )
 {
     int ret, cnt_restart;
-    mbedtls_ecdsa_restart_ctx rs_ctx;
+    mbedtls_pk_restart_ctx rs_ctx;
     mbedtls_pk_context prv, pub;
     unsigned char hash[MBEDTLS_MD_MAX_SIZE];
     unsigned char sig[MBEDTLS_ECDSA_MAX_LEN];
@@ -282,7 +282,7 @@ void pk_sign_verify_restart( int pk_type, int grp_id, char *d_str,
     size_t hlen, slen, slen_check;
     const mbedtls_md_info_t *md_info;
 
-    mbedtls_ecdsa_restart_init( &rs_ctx );
+    mbedtls_pk_restart_init( &rs_ctx );
     mbedtls_pk_init( &prv );
     mbedtls_pk_init( &pub );
     memset( hash, 0, sizeof( hash ) );
@@ -351,7 +351,7 @@ void pk_sign_verify_restart( int pk_type, int grp_id, char *d_str,
     ret = mbedtls_pk_verify_restartable( &pub, md_alg,
                              hash, hlen, sig, slen, &rs_ctx );
     TEST_ASSERT( ret == 0 || ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
-    mbedtls_ecdsa_restart_free( &rs_ctx );
+    mbedtls_pk_restart_free( &rs_ctx );
 
     slen = sizeof( sig );
     ret = mbedtls_pk_sign_restartable( &prv, md_alg, hash, hlen,
@@ -359,7 +359,7 @@ void pk_sign_verify_restart( int pk_type, int grp_id, char *d_str,
     TEST_ASSERT( ret == 0 || ret == MBEDTLS_ERR_ECP_IN_PROGRESS );
 
 exit:
-    mbedtls_ecdsa_restart_free( &rs_ctx );
+    mbedtls_pk_restart_free( &rs_ctx );
     mbedtls_pk_free( &prv );
     mbedtls_pk_free( &pub );
 }
@@ -373,10 +373,10 @@ void pk_sign_verify( int type, int sign_ret, int verify_ret )
     size_t sig_len;
     void *rs_ctx = NULL;
 #if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
-    mbedtls_ecdsa_restart_ctx ctx;
+    mbedtls_pk_restart_ctx ctx;
 
     rs_ctx = &ctx;
-    mbedtls_ecdsa_restart_init( rs_ctx );
+    mbedtls_pk_restart_init( rs_ctx );
     mbedtls_ecp_set_max_ops( 42000 );
 #endif
 
@@ -429,7 +429,7 @@ void pk_sign_verify( int type, int sign_ret, int verify_ret )
 
 exit:
 #if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
-    mbedtls_ecdsa_restart_free( rs_ctx );
+    mbedtls_pk_restart_free( rs_ctx );
 #endif
     mbedtls_pk_free( &pk );
 }