From: jsing Date: Thu, 2 Feb 2023 18:39:26 +0000 (+0000) Subject: Refactor BN_uadd() and BN_usub(). X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=37c495458b48d3b5213976a88978cadadf00bcd7;p=openbsd Refactor BN_uadd() and BN_usub(). Unlike bn_add_words()/bn_sub_words(), the s2n-bignum bignum_add() and bignum_sub() functions correctly handle inputs with differing word lengths. This means that they can be called directly, without needing to fix up any remaining words manually. Split BN_uadd() in two - the default bn_add() implementation calls bn_add_words(), before handling the carry for any remaining words. Likewise split BN_usub() in two - the default bn_sub() implementation calls bn_sub_words(), before handling the borrow for any remaining words. On amd64, provide an implementation of bn_add() that calls s2n-bignum's bignum_add() directly, similarly with an implementation of bn_sub() that calls s2n-bignum's bignum_sub() directly. ok tb@ --- diff --git a/lib/libcrypto/bn/arch/amd64/bn_arch.c b/lib/libcrypto/bn/arch/amd64/bn_arch.c index aedefc76e22..dc3000fe8bd 100644 --- a/lib/libcrypto/bn/arch/amd64/bn_arch.c +++ b/lib/libcrypto/bn/arch/amd64/bn_arch.c @@ -1,4 +1,4 @@ -/* $OpenBSD: bn_arch.c,v 1.2 2023/01/29 14:00:41 jsing Exp $ */ +/* $OpenBSD: bn_arch.c,v 1.3 2023/02/02 18:39:26 jsing Exp $ */ /* * Copyright (c) 2023 Joel Sing * @@ -21,6 +21,15 @@ #include "bn_local.h" #include "s2n_bignum.h" +#ifdef HAVE_BN_ADD +BN_ULONG +bn_add(BIGNUM *r, int rn, const BIGNUM *a, const BIGNUM *b) +{ + return bignum_add(rn, (uint64_t *)r->d, a->top, (uint64_t *)a->d, + b->top, (uint64_t *)b->d); +} +#endif + #ifdef HAVE_BN_ADD_WORDS BN_ULONG bn_add_words(BN_ULONG *rd, const BN_ULONG *ad, const BN_ULONG *bd, int n) @@ -30,6 +39,15 @@ bn_add_words(BN_ULONG *rd, const BN_ULONG *ad, const BN_ULONG *bd, int n) } #endif +#ifdef HAVE_BN_SUB +BN_ULONG +bn_sub(BIGNUM *r, int rn, const BIGNUM *a, const BIGNUM *b) +{ + return bignum_sub(rn, (uint64_t *)r->d, a->top, (uint64_t *)a->d, + b->top, (uint64_t *)b->d); +} +#endif + #ifdef HAVE_BN_SUB_WORDS BN_ULONG bn_sub_words(BN_ULONG *rd, const BN_ULONG *ad, const BN_ULONG *bd, int n) diff --git a/lib/libcrypto/bn/arch/amd64/bn_arch.h b/lib/libcrypto/bn/arch/amd64/bn_arch.h index 9e4b6b94426..c41a84409b6 100644 --- a/lib/libcrypto/bn/arch/amd64/bn_arch.h +++ b/lib/libcrypto/bn/arch/amd64/bn_arch.h @@ -1,4 +1,4 @@ -/* $OpenBSD: bn_arch.h,v 1.9 2023/01/31 05:53:49 jsing Exp $ */ +/* $OpenBSD: bn_arch.h,v 1.10 2023/02/02 18:39:26 jsing Exp $ */ /* * Copyright (c) 2023 Joel Sing * @@ -22,6 +22,7 @@ #ifndef OPENSSL_NO_ASM +#define HAVE_BN_ADD #define HAVE_BN_ADD_WORDS #define HAVE_BN_DIV_WORDS @@ -36,6 +37,7 @@ #define HAVE_BN_SQR_COMBA8 #define HAVE_BN_SQR_WORDS +#define HAVE_BN_SUB #define HAVE_BN_SUB_WORDS #if defined(__GNUC__) diff --git a/lib/libcrypto/bn/bn_add.c b/lib/libcrypto/bn/bn_add.c index cfc04fd0323..dc525db0840 100644 --- a/lib/libcrypto/bn/bn_add.c +++ b/lib/libcrypto/bn/bn_add.c @@ -1,4 +1,4 @@ -/* $OpenBSD: bn_add.c,v 1.20 2023/01/31 05:16:52 jsing Exp $ */ +/* $OpenBSD: bn_add.c,v 1.21 2023/02/02 18:39:26 jsing Exp $ */ /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * @@ -57,6 +57,7 @@ */ #include +#include #include #include @@ -64,6 +65,9 @@ #include "bn_arch.h" #include "bn_local.h" +BN_ULONG bn_add(BIGNUM *r, int rn, const BIGNUM *a, const BIGNUM *b); +BN_ULONG bn_sub(BIGNUM *r, int rn, const BIGNUM *a, const BIGNUM *b); + #ifndef HAVE_BN_ADD_WORDS #ifdef BN_LLONG BN_ULONG @@ -220,13 +224,18 @@ bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, int n) } #endif -int -BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) +#ifndef HAVE_BN_ADD +/* + * bn_add() computes a + b, storing the result in r (which may be the same as a + * or b). The caller must ensure that r has been expanded to max(a->top, b->top) + * words. Any carry resulting from the addition is returned. + */ +BN_ULONG +bn_add(BIGNUM *r, int rn, const BIGNUM *a, const BIGNUM *b) { - int max, min, dif; - const BN_ULONG *ap, *bp; BN_ULONG *rp, carry, t1, t2; - + const BN_ULONG *ap, *bp; + int max, min, dif; if (a->top < b->top) { const BIGNUM *tmp; @@ -239,11 +248,6 @@ BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) min = b->top; dif = max - min; - if (!bn_wexpand(r, max + 1)) - return 0; - - r->top = max; - ap = a->d; bp = b->d; rp = r->d; @@ -259,42 +263,34 @@ BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) *(rp++) = t2; carry &= (t2 == 0); } - *rp = carry; - r->top += carry; - r->neg = 0; - return 1; + return carry; } +#endif -int -BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) +#ifndef HAVE_BN_SUB +/* + * bn_sub() computes a - b, storing the result in r (which may be the same as a + * or b). The caller must ensure that the number of words in a is greater than + * or equal to the number of words in b and that r has been expanded to + * a->top words. Any borrow resulting from the subtraction is returned. + */ +BN_ULONG +bn_sub(BIGNUM *r, int rn, const BIGNUM *a, const BIGNUM *b) { - int max, min, dif; - const BN_ULONG *ap, *bp; BN_ULONG t1, t2, borrow, *rp; - + const BN_ULONG *ap, *bp; + int max, min, dif; max = a->top; min = b->top; dif = max - min; - if (dif < 0) { - BNerror(BN_R_ARG2_LT_ARG3); - return 0; - } - - if (!bn_wexpand(r, max)) - return 0; - ap = a->d; bp = b->d; rp = r->d; borrow = bn_sub_words(rp, ap, bp, min); - if (dif == 0 && borrow > 0) { - BNerror(BN_R_ARG2_LT_ARG3); - return 0; - } ap += min; rp += min; @@ -306,12 +302,58 @@ BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) borrow &= (t1 == 0); } - while (max > 0 && *--rp == 0) - max--; + return borrow; +} +#endif + +int +BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) +{ + BN_ULONG carry; + int rn; + + if ((rn = a->top) < b->top) + rn = b->top; + if (rn == INT_MAX) + return 0; + if (!bn_wexpand(r, rn + 1)) + return 0; + + carry = bn_add(r, rn, a, b); + r->d[rn] = carry; + + r->top = rn + (carry & 1); + r->neg = 0; + + return 1; +} + +int +BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) +{ + BN_ULONG borrow; + int rn; + + if (a->top < b->top) { + BNerror(BN_R_ARG2_LT_ARG3); + return 0; + } + rn = a->top; + + if (!bn_wexpand(r, rn)) + return 0; - r->top = max; + borrow = bn_sub(r, rn, a, b); + if (borrow > 0) { + BNerror(BN_R_ARG2_LT_ARG3); + return 0; + } + + r->top = rn; r->neg = 0; + bn_correct_top(r); + return 1; } @@ -320,7 +362,6 @@ BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { int ret, r_neg; - if (a->neg == b->neg) { r_neg = a->neg; ret = BN_uadd(r, a, b); @@ -349,7 +390,6 @@ BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { int ret, r_neg; - if (a->neg != b->neg) { r_neg = a->neg; ret = BN_uadd(r, a, b);