Merge pull request #2019 from gilles-peskine-arm/build_with_only_mont…

…gomery_curves-conditional_mul_add Build with only Montgomery curves (conditional mul_add)
Mbed-TLS · Jul 22, 2020 · ee7e85f · ee7e85f
2 parents 8f4f9a8 + 6d9c8d7
commit ee7e85f
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diff --git a/ChangeLog.d/build_with_only_montgomery_curves.txt b/ChangeLog.d/build_with_only_montgomery_curves.txt
@@ -0,0 +1,6 @@
+Bugfix
+   * Fix build errors when the only enabled elliptic curves are Montgomery
+     curves. Raised by signpainter in #941 and by Taiki-San in #1412. This
+     also fixes missing declarations reported by Steven Cooreman in #1147.
+   * Fix self-test failure when the only enabled short Weierstrass elliptic
+     curve is secp192k1. Fixes #2017.
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
@@ -103,6 +103,17 @@
 
 #if defined(MBEDTLS_ECDSA_C) &&            \
     ( !defined(MBEDTLS_ECP_C) ||           \
+      !( defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP192K1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP224K1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED) || \
+         defined(MBEDTLS_ECP_DP_BP256R1_ENABLED) ||   \
+         defined(MBEDTLS_ECP_DP_BP384R1_ENABLED) ||   \
+         defined(MBEDTLS_ECP_DP_BP512R1_ENABLED) ) || \
       !defined(MBEDTLS_ASN1_PARSE_C) ||    \
       !defined(MBEDTLS_ASN1_WRITE_C) )
 #error "MBEDTLS_ECDSA_C defined, but not all prerequisites"
@@ -246,12 +257,14 @@
 #endif
 
 #if defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED) &&                 \
-    ( !defined(MBEDTLS_ECDH_C) || !defined(MBEDTLS_X509_CRT_PARSE_C) )
+    ( !defined(MBEDTLS_ECDH_C) || !defined(MBEDTLS_ECDSA_C) ||          \
+      !defined(MBEDTLS_X509_CRT_PARSE_C) )
 #error "MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED defined, but not all prerequisites"
 #endif
 
 #if defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED) &&                 \
-    ( !defined(MBEDTLS_ECDH_C) || !defined(MBEDTLS_X509_CRT_PARSE_C) )
+    ( !defined(MBEDTLS_ECDH_C) || !defined(MBEDTLS_RSA_C) ||          \
+      !defined(MBEDTLS_X509_CRT_PARSE_C) )
 #error "MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED defined, but not all prerequisites"
 #endif
 

diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
@@ -756,6 +756,7 @@
  *
  * Comment macros to disable the curve and functions for it
  */
+/* Short Weierstrass curves (supporting ECP, ECDH, ECDSA) */
 #define MBEDTLS_ECP_DP_SECP192R1_ENABLED
 #define MBEDTLS_ECP_DP_SECP224R1_ENABLED
 #define MBEDTLS_ECP_DP_SECP256R1_ENABLED
@@ -767,6 +768,7 @@
 #define MBEDTLS_ECP_DP_BP256R1_ENABLED
 #define MBEDTLS_ECP_DP_BP384R1_ENABLED
 #define MBEDTLS_ECP_DP_BP512R1_ENABLED
+/* Montgomery curves (supporting ECP) */
 #define MBEDTLS_ECP_DP_CURVE25519_ENABLED
 #define MBEDTLS_ECP_DP_CURVE448_ENABLED
 
@@ -1083,7 +1085,7 @@
  *
  * Enable the ECDH-ECDSA based ciphersuite modes in SSL / TLS.
  *
- * Requires: MBEDTLS_ECDH_C, MBEDTLS_X509_CRT_PARSE_C
+ * Requires: MBEDTLS_ECDH_C, MBEDTLS_ECDSA_C, MBEDTLS_X509_CRT_PARSE_C
  *
  * This enables the following ciphersuites (if other requisites are
  * enabled as well):
@@ -1107,7 +1109,7 @@
  *
  * Enable the ECDH-RSA based ciphersuite modes in SSL / TLS.
  *
- * Requires: MBEDTLS_ECDH_C, MBEDTLS_X509_CRT_PARSE_C
+ * Requires: MBEDTLS_ECDH_C, MBEDTLS_RSA_C, MBEDTLS_X509_CRT_PARSE_C
  *
  * This enables the following ciphersuites (if other requisites are
  * enabled as well):
@@ -2571,7 +2573,9 @@
  * This module is used by the following key exchanges:
  *      ECDHE-ECDSA
  *
- * Requires: MBEDTLS_ECP_C, MBEDTLS_ASN1_WRITE_C, MBEDTLS_ASN1_PARSE_C
+ * Requires: MBEDTLS_ECP_C, MBEDTLS_ASN1_WRITE_C, MBEDTLS_ASN1_PARSE_C,
+ *           and at least one MBEDTLS_ECP_DP_XXX_ENABLED for a
+ *           short Weierstrass curve.
  */
 #define MBEDTLS_ECDSA_C
 

diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
@@ -61,6 +61,26 @@
 
 #define MBEDTLS_ERR_ECP_IN_PROGRESS                       -0x4B00  /**< Operation in progress, call again with the same parameters to continue. */
 
+/* Flags indicating whether to include code that is specific to certain
+ * types of curves. These flags are for internal library use only. */
+#if defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_BP256R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_BP384R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_BP512R1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP192K1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP224K1_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_SECP256K1_ENABLED)
+#define MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED
+#endif
+#if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED) || \
+    defined(MBEDTLS_ECP_DP_CURVE448_ENABLED)
+#define MBEDTLS_ECP_MONTGOMERY_ENABLED
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -74,6 +94,20 @@ extern "C" {
  * parameters. Therefore, only standardized domain parameters from trusted
  * sources should be used. See mbedtls_ecp_group_load().
  */
+/* Note: when adding a new curve:
+ * - Add it at the end of this enum, otherwise you'll break the ABI by
+ *   changing the numerical value for existing curves.
+ * - Increment MBEDTLS_ECP_DP_MAX below if needed.
+ * - Add the corresponding MBEDTLS_ECP_DP_xxx_ENABLED macro definition to
+ *   config.h.
+ * - List the curve as a dependency of MBEDTLS_ECP_C and
+ *   MBEDTLS_ECDSA_C if supported in check_config.h.
+ * - Add the curve to the appropriate curve type macro
+ *   MBEDTLS_ECP_yyy_ENABLED above.
+ * - Add the necessary definitions to ecp_curves.c.
+ * - Add the curve to the ecp_supported_curves array in ecp.c.
+ * - Add the curve to applicable profiles in x509_crt.c if applicable.
+ */
 typedef enum
 {
     MBEDTLS_ECP_DP_NONE = 0,       /*!< Curve not defined. */
@@ -906,6 +940,7 @@ int mbedtls_ecp_mul_restartable( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
              mbedtls_ecp_restart_ctx *rs_ctx );
 
+#if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
 /**
  * \brief           This function performs multiplication and addition of two
  *                  points by integers: \p R = \p m * \p P + \p n * \p Q
@@ -915,6 +950,10 @@ int mbedtls_ecp_mul_restartable( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
  * \note            In contrast to mbedtls_ecp_mul(), this function does not
  *                  guarantee a constant execution flow and timing.
  *
+ * \note            This function is only defined for short Weierstrass curves.
+ *                  It may not be included in builds without any short
+ *                  Weierstrass curve.
+ *
  * \param grp       The ECP group to use.
  *                  This must be initialized and have group parameters
  *                  set, for example through mbedtls_ecp_group_load().
@@ -933,6 +972,8 @@ int mbedtls_ecp_mul_restartable( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
  *                  valid private keys, or \p P or \p Q are not valid public
  *                  keys.
  * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
+ * \return          #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if \p grp does not
+ *                  designate a short Weierstrass curve.
  * \return          Another negative error code on other kinds of failure.
  */
 int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
@@ -950,6 +991,10 @@ int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
  *                  but it can return early and restart according to the limit
  *                  set with \c mbedtls_ecp_set_max_ops() to reduce blocking.
  *
+ * \note            This function is only defined for short Weierstrass curves.
+ *                  It may not be included in builds without any short
+ *                  Weierstrass curve.
+ *
  * \param grp       The ECP group to use.
  *                  This must be initialized and have group parameters
  *                  set, for example through mbedtls_ecp_group_load().
@@ -969,6 +1014,8 @@ int mbedtls_ecp_muladd( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
  *                  valid private keys, or \p P or \p Q are not valid public
  *                  keys.
  * \return          #MBEDTLS_ERR_MPI_ALLOC_FAILED on memory-allocation failure.
+ * \return          #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if \p grp does not
+ *                  designate a short Weierstrass curve.
  * \return          #MBEDTLS_ERR_ECP_IN_PROGRESS if maximum number of
  *                  operations was reached: see \c mbedtls_ecp_set_max_ops().
  * \return          Another negative error code on other kinds of failure.
@@ -978,6 +1025,7 @@ int mbedtls_ecp_muladd_restartable(
              const mbedtls_mpi *m, const mbedtls_ecp_point *P,
              const mbedtls_mpi *n, const mbedtls_ecp_point *Q,
              mbedtls_ecp_restart_ctx *rs_ctx );
+#endif /* MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
 
 /**
  * \brief           This function checks that a point is a valid public key

diff --git a/include/mbedtls/ecp_internal.h b/include/mbedtls/ecp_internal.h
@@ -105,7 +105,7 @@ int mbedtls_internal_ecp_init( const mbedtls_ecp_group *grp );
  */
 void mbedtls_internal_ecp_free( const mbedtls_ecp_group *grp );
 
-#if defined(ECP_SHORTWEIERSTRASS)
+#if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
 
 #if defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT)
 /**
@@ -245,9 +245,9 @@ int mbedtls_internal_ecp_normalize_jac( const mbedtls_ecp_group *grp,
         mbedtls_ecp_point *pt );
 #endif
 
-#endif /* ECP_SHORTWEIERSTRASS */
+#endif /* MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
 
-#if defined(ECP_MONTGOMERY)
+#if defined(MBEDTLS_ECP_MONTGOMERY_ENABLED)
 
 #if defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT)
 int mbedtls_internal_ecp_double_add_mxz( const mbedtls_ecp_group *grp,
@@ -291,7 +291,7 @@ int mbedtls_internal_ecp_normalize_mxz( const mbedtls_ecp_group *grp,
         mbedtls_ecp_point *P );
 #endif
 
-#endif /* ECP_MONTGOMERY */
+#endif /* MBEDTLS_ECP_MONTGOMERY_ENABLED */
 
 #endif /* MBEDTLS_ECP_INTERNAL_ALT */