diff --git a/ChangeLog.d/no_ecp_fallback.txt b/ChangeLog.d/no_ecp_fallback.txt new file mode 100644 index 000000000..f61d3117d --- /dev/null +++ b/ChangeLog.d/no_ecp_fallback.txt @@ -0,0 +1,4 @@ +Features + * Automatic fallback to a software implementation of ECP when + MBEDTLS_ECP_xxx_ALT accelerator hooks are in use can now be turned off + through setting the new configuration flag MBEDTLS_ECP_NO_FALLBACK. diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h index 7f403c1e4..a6545ab5b 100644 --- a/include/mbedtls/check_config.h +++ b/include/mbedtls/check_config.h @@ -252,6 +252,10 @@ #error "MBEDTLS_ECP_NORMALIZE_MXZ_ALT defined, but not all prerequisites" #endif +#if defined(MBEDTLS_ECP_NO_FALLBACK) && !defined(MBEDTLS_ECP_INTERNAL_ALT) +#error "MBEDTLS_ECP_NO_FALLBACK defined, but no alternative implementation enabled" +#endif + #if defined(MBEDTLS_HAVEGE_C) && !defined(MBEDTLS_TIMING_C) #error "MBEDTLS_HAVEGE_C defined, but not all prerequisites" #endif diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h index b563a96b7..251d4f057 100644 --- a/include/mbedtls/config.h +++ b/include/mbedtls/config.h @@ -484,6 +484,11 @@ * is still present and it is used for group structures not supported by the * alternative. * + * The original implementation can in addition be removed by setting the + * MBEDTLS_ECP_NO_FALLBACK option, in which case any function for which the + * corresponding MBEDTLS_ECP__FUNCTION_NAME__ALT macro is defined will not be + * able to fallback to curves not supported by the alternative implementation. + * * Any of these options become available by defining MBEDTLS_ECP_INTERNAL_ALT * and implementing the following functions: * unsigned char mbedtls_internal_ecp_grp_capable( @@ -497,21 +502,28 @@ * called before and after each point operation and provide an opportunity to * implement optimized set up and tear down instructions. * - * Example: In case you uncomment MBEDTLS_ECP_INTERNAL_ALT and - * MBEDTLS_ECP_DOUBLE_JAC_ALT, mbed TLS will still provide the ecp_double_jac - * function, but will use your mbedtls_internal_ecp_double_jac if the group is - * supported (your mbedtls_internal_ecp_grp_capable function returns 1 when - * receives it as an argument). If the group is not supported then the original - * implementation is used. The other functions and the definition of - * mbedtls_ecp_group and mbedtls_ecp_point will not change, so your - * implementation of mbedtls_internal_ecp_double_jac and - * mbedtls_internal_ecp_grp_capable must be compatible with this definition. + * Example: In case you set MBEDTLS_ECP_INTERNAL_ALT and + * MBEDTLS_ECP_DOUBLE_JAC_ALT, mbed TLS will still provide the ecp_double_jac() + * function, but will use your mbedtls_internal_ecp_double_jac() if the group + * for the operation is supported by your implementation (i.e. your + * mbedtls_internal_ecp_grp_capable() function returns 1 for this group). If the + * group is not supported by your implementation, then the original mbed TLS + * implementation of ecp_double_jac() is used instead, unless this fallback + * behaviour is disabled by setting MBEDTLS_ECP_NO_FALLBACK (in which case + * ecp_double_jac() will return MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE). + * + * The function prototypes and the definition of mbedtls_ecp_group and + * mbedtls_ecp_point will not change based on MBEDTLS_ECP_INTERNAL_ALT, so your + * implementation of mbedtls_internal_ecp__function_name__ must be compatible + * with their definitions. * * Uncomment a macro to enable alternate implementation of the corresponding * function. */ /* Required for all the functions in this section */ //#define MBEDTLS_ECP_INTERNAL_ALT +/* Turn off software fallback for curves not supported in hardware */ +//#define MBEDTLS_ECP_NO_FALLBACK /* Support for Weierstrass curves with Jacobi representation */ //#define MBEDTLS_ECP_RANDOMIZE_JAC_ALT //#define MBEDTLS_ECP_ADD_MIXED_ALT diff --git a/library/ecp.c b/library/ecp.c index 05a0b0175..3b68e8e2d 100644 --- a/library/ecp.c +++ b/library/ecp.c @@ -1302,9 +1302,6 @@ cleanup: */ static int ecp_normalize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *pt ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi Zi, ZZi; - if( mbedtls_mpi_cmp_int( &pt->Z, 0 ) == 0 ) return( 0 ); @@ -1313,6 +1310,11 @@ static int ecp_normalize_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *p 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) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi Zi, ZZi; mbedtls_mpi_init( &Zi ); mbedtls_mpi_init( &ZZi ); /* @@ -1338,6 +1340,7 @@ cleanup: mbedtls_mpi_free( &Zi ); mbedtls_mpi_free( &ZZi ); return( ret ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_ALT) */ } /* @@ -1354,10 +1357,6 @@ cleanup: static int ecp_normalize_jac_many( const mbedtls_ecp_group *grp, mbedtls_ecp_point *T[], size_t T_size ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - size_t i; - mbedtls_mpi *c, u, Zi, ZZi; - if( T_size < 2 ) return( ecp_normalize_jac( grp, *T ) ); @@ -1366,6 +1365,13 @@ static int ecp_normalize_jac_many( const mbedtls_ecp_group *grp, 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) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + size_t i; + mbedtls_mpi *c, u, Zi, ZZi; + if( ( c = mbedtls_calloc( T_size, sizeof( mbedtls_mpi ) ) ) == NULL ) return( MBEDTLS_ERR_ECP_ALLOC_FAILED ); @@ -1433,6 +1439,7 @@ cleanup: mbedtls_free( c ); return( ret ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_JAC_MANY_ALT) */ } /* @@ -1477,9 +1484,6 @@ cleanup: static int ecp_double_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R, const mbedtls_ecp_point *P ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi M, S, T, U; - #if defined(MBEDTLS_SELF_TEST) dbl_count++; #endif @@ -1489,6 +1493,12 @@ static int ecp_double_jac( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R, 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) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi M, S, T, U; + mbedtls_mpi_init( &M ); mbedtls_mpi_init( &S ); mbedtls_mpi_init( &T ); mbedtls_mpi_init( &U ); /* Special case for A = -3 */ @@ -1550,6 +1560,7 @@ cleanup: mbedtls_mpi_free( &M ); mbedtls_mpi_free( &S ); mbedtls_mpi_free( &T ); mbedtls_mpi_free( &U ); return( ret ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_DOUBLE_JAC_ALT) */ } /* @@ -1573,9 +1584,6 @@ cleanup: static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R, const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi T1, T2, T3, T4, X, Y, Z; - #if defined(MBEDTLS_SELF_TEST) add_count++; #endif @@ -1585,6 +1593,12 @@ static int ecp_add_mixed( const mbedtls_ecp_group *grp, mbedtls_ecp_point *R, 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) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi T1, T2, T3, T4, X, Y, Z; + /* * Trivial cases: P == 0 or Q == 0 (case 1) */ @@ -1649,6 +1663,7 @@ cleanup: mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z ); return( ret ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_ADD_MIXED_ALT) */ } /* @@ -1661,17 +1676,19 @@ cleanup: 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 ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi l, ll; - size_t p_size; - int count = 0; - #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 */ - p_size = ( grp->pbits + 7 ) / 8; +#if defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi l, ll; + int count = 0; + size_t p_size = ( grp->pbits + 7 ) / 8; + mbedtls_mpi_init( &l ); mbedtls_mpi_init( &ll ); /* Generate l such that 1 < l < p */ @@ -1705,6 +1722,7 @@ cleanup: mbedtls_mpi_free( &l ); mbedtls_mpi_free( &ll ); return( ret ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) */ } /* @@ -2413,19 +2431,22 @@ cleanup: */ static int ecp_normalize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - #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) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 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 ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_NORMALIZE_MXZ_ALT) */ } /* @@ -2439,17 +2460,18 @@ cleanup: 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 ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi l; - size_t p_size; - int count = 0; - #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 */ - p_size = ( grp->pbits + 7 ) / 8; +#if defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi l; + int count = 0; + size_t p_size = ( grp->pbits + 7 ) / 8; mbedtls_mpi_init( &l ); /* Generate l such that 1 < l < p */ @@ -2475,6 +2497,7 @@ cleanup: mbedtls_mpi_free( &l ); return( ret ); +#endif /* !defined(MBEDTLS_ECP_NO_FALLBACK) || !defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT) */ } /* @@ -2497,14 +2520,17 @@ static int ecp_double_add_mxz( const mbedtls_ecp_group *grp, const mbedtls_ecp_point *P, const mbedtls_ecp_point *Q, const mbedtls_mpi *d ) { - int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; - mbedtls_mpi A, AA, B, BB, E, C, D, DA, CB; - #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) + return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE ); +#else + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + mbedtls_mpi A, AA, B, BB, E, C, D, DA, CB; + 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 +2560,7 @@ cleanup: mbedtls_mpi_free( &D ); mbedtls_mpi_free( &DA ); mbedtls_mpi_free( &CB ); return( ret ); +#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 80f121a0d..c6f46d9ec 100644 --- a/library/version_features.c +++ b/library/version_features.c @@ -225,6 +225,9 @@ static const char * const features[] = { #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 */ diff --git a/programs/test/query_config.c b/programs/test/query_config.c index aae8e2e12..0dc06c091 100644 --- a/programs/test/query_config.c +++ b/programs/test/query_config.c @@ -658,6 +658,14 @@ int query_config( const char *config ) } #endif /* MBEDTLS_ECP_INTERNAL_ALT */ +#if defined(MBEDTLS_ECP_NO_FALLBACK) + if( strcmp( "MBEDTLS_ECP_NO_FALLBACK", config ) == 0 ) + { + MACRO_EXPANSION_TO_STR( MBEDTLS_ECP_NO_FALLBACK ); + return( 0 ); + } +#endif /* MBEDTLS_ECP_NO_FALLBACK */ + #if defined(MBEDTLS_ECP_RANDOMIZE_JAC_ALT) if( strcmp( "MBEDTLS_ECP_RANDOMIZE_JAC_ALT", config ) == 0 ) { diff --git a/scripts/config.py b/scripts/config.py index b60f93d7d..01f570e17 100755 --- a/scripts/config.py +++ b/scripts/config.py @@ -171,6 +171,7 @@ EXCLUDE_FROM_FULL = frozenset([ 'MBEDTLS_DEPRECATED_REMOVED', # conflicts with deprecated options 'MBEDTLS_DEPRECATED_WARNING', # conflicts with deprecated options 'MBEDTLS_ECDH_VARIANT_EVEREST_ENABLED', # influences the use of ECDH in TLS + 'MBEDTLS_ECP_NO_FALLBACK', # removes internal ECP implementation 'MBEDTLS_ECP_NO_INTERNAL_RNG', # removes a feature 'MBEDTLS_ECP_RESTARTABLE', # incompatible with USE_PSA_CRYPTO 'MBEDTLS_ENTROPY_FORCE_SHA256', # interacts with CTR_DRBG_128_BIT_KEY