Add a flag for disabling fallback in ecp.c

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
diff --git a/library/ecp.c b/library/ecp.c
index 05a0b01..044712f 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -1302,8 +1302,10 @@
  */
 static int ecp_normalize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *pt )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_mpi Zi, ZZi;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT) */
 
     if( mbedtls_mpi_cmp_int( &pt->Z, 0 ) == 0 )
         return( 0 );
@@ -1312,7 +1314,7 @@
     if( mbedtls_internal_ecp_grp_capable( grp ) )
         return( mbedtls_internal_ecp_normalize_jac( grp, pt ) );
 #endif /* MBEDTLS_ECP_NORMALIZE_JAC_ALT */
-
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT)
     mbedtls_mpi_init( &Zi ); mbedtls_mpi_init( &ZZi );
 
     /*
@@ -1338,6 +1340,9 @@
     mbedtls_mpi_free( &Zi ); mbedtls_mpi_free( &ZZi );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT) */
 }
 
 /*
@@ -1354,9 +1359,11 @@
 static int ecp_normalize_jac_many( const mbedtls_ecp_group *grp,
                                    mbedtls_ecp_point *T[], size_t T_size )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t i;
     mbedtls_mpi *c, u, Zi, ZZi;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT) */
 
     if( T_size < 2 )
         return( ecp_normalize_jac( grp, *T ) );
@@ -1366,6 +1373,7 @@
         return( mbedtls_internal_ecp_normalize_jac_many( grp, T, T_size ) );
 #endif
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT)
     if( ( c = mbedtls_calloc( T_size, sizeof( mbedtls_mpi ) ) ) == NULL )
         return( MBEDTLS_ERR_ECP_ALLOC_FAILED );
 
@@ -1433,6 +1441,9 @@
     mbedtls_free( c );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT) */
 }
 
 /*
@@ -1477,8 +1488,10 @@
 static int ecp_double_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
                            const mbedtls_ecp_point *P )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_JAC_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_mpi M, S, T, U;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_JAC_ALT) */
 
 #if defined(MBEDTLS_SELF_TEST)
     dbl_count++;
@@ -1489,6 +1502,7 @@
         return( mbedtls_internal_ecp_double_jac( grp, R, P ) );
 #endif /* MBEDTLS_ECP_DOUBLE_JAC_ALT */
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_JAC_ALT)
     mbedtls_mpi_init( &M ); mbedtls_mpi_init( &S ); mbedtls_mpi_init( &T ); mbedtls_mpi_init( &U );
 
     /* Special case for A = -3 */
@@ -1550,6 +1564,9 @@
     mbedtls_mpi_free( &M ); mbedtls_mpi_free( &S ); mbedtls_mpi_free( &T ); mbedtls_mpi_free( &U );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_JAC_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_DOUBLE_JAC_ALT) */
 }
 
 /*
@@ -1573,8 +1590,10 @@
 static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
                           const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_mpi T1, T2, T3, T4, X, Y, Z;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT) */
 
 #if defined(MBEDTLS_SELF_TEST)
     add_count++;
@@ -1585,6 +1604,7 @@
         return( mbedtls_internal_ecp_add_mixed( grp, R, P, Q ) );
 #endif /* MBEDTLS_ECP_ADD_MIXED_ALT */
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT)
     /*
      * Trivial cases: P == 0 or Q == 0 (case 1)
      */
@@ -1649,6 +1669,9 @@
     mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_ADD_MIXED_ALT) */
 }
 
 /*
@@ -1661,16 +1684,19 @@
 static int ecp_randomize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *pt,
                 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_mpi l, ll;
     size_t p_size;
     int count = 0;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) */
 
 #if defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT)
     if( mbedtls_internal_ecp_grp_capable( grp ) )
         return( mbedtls_internal_ecp_randomize_jac( grp, pt, f_rng, p_rng ) );
 #endif /* MBEDTLS_ECP_RANDOMIZE_JAC_ALT */
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT)
     p_size = ( grp->pbits + 7 ) / 8;
     mbedtls_mpi_init( &l ); mbedtls_mpi_init( &ll );
 
@@ -1705,6 +1731,9 @@
     mbedtls_mpi_free( &l ); mbedtls_mpi_free( &ll );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) */
 }
 
 /*
@@ -2413,19 +2442,25 @@
  */
 static int ecp_normalize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT) */
 
 #if defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT)
     if( mbedtls_internal_ecp_grp_capable( grp ) )
         return( mbedtls_internal_ecp_normalize_mxz( grp, P ) );
 #endif /* MBEDTLS_ECP_NORMALIZE_MXZ_ALT */
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT)
     MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &P->Z, &P->Z, &grp->P ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &P->X, &P->X, &P->Z ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &P->Z, 1 ) );
 
 cleanup:
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT) */
 }
 
 /*
@@ -2439,16 +2474,19 @@
 static int ecp_randomize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P,
                 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_mpi l;
     size_t p_size;
     int count = 0;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT) */
 
 #if defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
     if( mbedtls_internal_ecp_grp_capable( grp ) )
         return( mbedtls_internal_ecp_randomize_mxz( grp, P, f_rng, p_rng );
 #endif /* MBEDTLS_ECP_RANDOMIZE_MXZ_ALT */
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
     p_size = ( grp->pbits + 7 ) / 8;
     mbedtls_mpi_init( &l );
 
@@ -2475,6 +2513,9 @@
     mbedtls_mpi_free( &l );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT) */
 }
 
 /*
@@ -2497,14 +2538,17 @@
                                const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q,
                                const mbedtls_mpi *d )
 {
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT)
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     mbedtls_mpi A, AA, B, BB, E, C, D, DA, CB;
+#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT) */
 
 #if defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT)
     if( mbedtls_internal_ecp_grp_capable( grp ) )
         return( mbedtls_internal_ecp_double_add_mxz( grp, R, S, P, Q, d ) );
 #endif /* MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT */
 
+#if !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT)
     mbedtls_mpi_init( &A ); mbedtls_mpi_init( &AA ); mbedtls_mpi_init( &B );
     mbedtls_mpi_init( &BB ); mbedtls_mpi_init( &E ); mbedtls_mpi_init( &C );
     mbedtls_mpi_init( &D ); mbedtls_mpi_init( &DA ); mbedtls_mpi_init( &CB );
@@ -2534,6 +2578,9 @@
     mbedtls_mpi_free( &D ); mbedtls_mpi_free( &DA ); mbedtls_mpi_free( &CB );
 
     return( ret );
+#else /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT) */
+    return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
+#endif /* defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_DOUBLE_ADD_MXZ_ALT) */
 }
 
 /*
diff --git a/library/version_features.c b/library/version_features.c
index 80f121a..c6f46d9 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -225,6 +225,9 @@
 #if defined(MBEDTLS_ECP_INTERNAL_ALT)
     "MBEDTLS_ECP_INTERNAL_ALT",
 #endif /* MBEDTLS_ECP_INTERNAL_ALT */
+#if defined(MBEDTLS_ECP_NO_FALLBACK)
+    "MBEDTLS_ECP_NO_FALLBACK",
+#endif /* MBEDTLS_ECP_NO_FALLBACK */
 #if defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT)
     "MBEDTLS_ECP_RANDOMIZE_JAC_ALT",
 #endif /* MBEDTLS_ECP_RANDOMIZE_JAC_ALT */