X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fbn%2Fbn_div.c;h=034a80a4a63f5f363b142e0cd53925971e8322fa;hp=d0b68dc246e7c6d8f24242c1e0db9fa8d6b4be75;hb=2218c296b4981af6f2639bbd7eabfb89437fe776;hpb=500230ee94ef5fc9d08b3cf7c92996f4366f1584 diff --git a/crypto/bn/bn_div.c b/crypto/bn/bn_div.c index d0b68dc246..034a80a4a6 100644 --- a/crypto/bn/bn_div.c +++ b/crypto/bn/bn_div.c @@ -56,6 +56,8 @@ * [including the GNU Public Licence.] */ +#define OPENSSL_FIPSAPI + #include #include #include "cryptlib.h" @@ -102,7 +104,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, /* The next 2 are needed so we can do a dv->d[0]|=1 later * since BN_lshift1 will only work once there is a value :-) */ BN_zero(dv); - bn_wexpand(dv,1); + if(bn_wexpand(dv,1) == NULL) goto end; dv->top=1; if (!BN_lshift(D,D,nm-nd)) goto end; @@ -130,7 +132,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, #if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \ && !defined(PEDANTIC) && !defined(BN_DIV3W) # if defined(__GNUC__) && __GNUC__>=2 -# if defined(__i386) +# if defined(__i386) || defined (__i386__) /* * There were two reasons for implementing this template: * - GNU C generates a call to a function (__udivdi3 to be exact) @@ -141,6 +143,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, * * */ +#undef bn_div_words # define bn_div_words(n0,n1,d0) \ ({ asm volatile ( \ "divl %4" \ @@ -150,13 +153,28 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, q; \ }) # define REMAINDER_IS_ALREADY_CALCULATED +# elif defined(__x86_64) && defined(SIXTY_FOUR_BIT_LONG) + /* + * Same story here, but it's 128-bit by 64-bit division. Wow! + * + */ +# undef bn_div_words +# define bn_div_words(n0,n1,d0) \ + ({ asm volatile ( \ + "divq %4" \ + : "=a"(q), "=d"(rem) \ + : "a"(n1), "d"(n0), "g"(d0) \ + : "cc"); \ + q; \ + }) +# define REMAINDER_IS_ALREADY_CALCULATED # endif /* __ */ # endif /* __GNUC__ */ #endif /* OPENSSL_NO_ASM */ -/* BN_div computes dv := num / divisor, rounding towards zero, and sets up - * rm such that dv*divisor + rm = num holds. +/* BN_div computes dv := num / divisor, rounding towards + * zero, and sets up rm such that dv*divisor + rm = num holds. * Thus: * dv->neg == num->neg ^ divisor->neg (unless the result is zero) * rm->neg == num->neg (unless the remainder is zero) @@ -165,13 +183,32 @@ int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, BN_CTX *ctx) { - int norm_shift,i,j,loop; + int norm_shift,i,loop; BIGNUM *tmp,wnum,*snum,*sdiv,*res; BN_ULONG *resp,*wnump; BN_ULONG d0,d1; int num_n,div_n; + int no_branch=0; + + /* Invalid zero-padding would have particularly bad consequences + * in the case of 'num', so don't just rely on bn_check_top() for this one + * (bn_check_top() works only for BN_DEBUG builds) */ + if (num->top > 0 && num->d[num->top - 1] == 0) + { + BNerr(BN_F_BN_DIV,BN_R_NOT_INITIALIZED); + return 0; + } bn_check_top(num); + + if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0)) + { + no_branch=1; + } + + bn_check_top(dv); + bn_check_top(rm); + /* bn_check_top(num); */ /* 'num' has been checked already */ bn_check_top(divisor); if (BN_is_zero(divisor)) @@ -180,7 +217,7 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, return(0); } - if (BN_ucmp(num,divisor) < 0) + if (!no_branch && BN_ucmp(num,divisor) < 0) { if (rm != NULL) { if (BN_copy(rm,num) == NULL) return(0); } @@ -195,30 +232,51 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, if (dv == NULL) res=BN_CTX_get(ctx); else res=dv; - if (sdiv == NULL || res == NULL) goto err; - tmp->neg=0; + if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL) + goto err; /* First we normalise the numbers */ norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2); - BN_lshift(sdiv,divisor,norm_shift); + if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err; sdiv->neg=0; norm_shift+=BN_BITS2; - BN_lshift(snum,num,norm_shift); + if (!(BN_lshift(snum,num,norm_shift))) goto err; snum->neg=0; + + if (no_branch) + { + /* Since we don't know whether snum is larger than sdiv, + * we pad snum with enough zeroes without changing its + * value. + */ + if (snum->top <= sdiv->top+1) + { + if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err; + for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0; + snum->top = sdiv->top + 2; + } + else + { + if (bn_wexpand(snum, snum->top + 1) == NULL) goto err; + snum->d[snum->top] = 0; + snum->top ++; + } + } + div_n=sdiv->top; num_n=snum->top; loop=num_n-div_n; - /* Lets setup a 'window' into snum * This is the part that corresponds to the current * 'area' being divided */ - BN_init(&wnum); - wnum.d= &(snum->d[loop]); - wnum.top= div_n; - wnum.dmax= snum->dmax+1; /* a bit of a lie */ + wnum.neg = 0; + wnum.d = &(snum->d[loop]); + wnum.top = div_n; + /* only needed when BN_ucmp messes up the values between top and max */ + wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */ /* Get the top 2 words of sdiv */ - /* i=sdiv->top; */ + /* div_n=sdiv->top; */ d0=sdiv->d[div_n-1]; d1=(div_n == 1)?0:sdiv->d[div_n-2]; @@ -228,27 +286,40 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, /* Setup to 'res' */ res->neg= (num->neg^divisor->neg); if (!bn_wexpand(res,(loop+1))) goto err; - res->top=loop; + res->top=loop-no_branch; resp= &(res->d[loop-1]); /* space for temp */ if (!bn_wexpand(tmp,(div_n+1))) goto err; - if (BN_ucmp(&wnum,sdiv) >= 0) + if (!no_branch) { - if (!BN_usub(&wnum,&wnum,sdiv)) goto err; - *resp=1; - res->d[res->top-1]=1; + if (BN_ucmp(&wnum,sdiv) >= 0) + { + /* If BN_DEBUG_RAND is defined BN_ucmp changes (via + * bn_pollute) the const bignum arguments => + * clean the values between top and max again */ + bn_clear_top2max(&wnum); + bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n); + *resp=1; + } + else + res->top--; } - else - res->top--; + + /* if res->top == 0 then clear the neg value otherwise decrease + * the resp pointer */ if (res->top == 0) res->neg = 0; - resp--; + else + resp--; - for (i=0; i 0x%08X\n", + n0, n1, d0, q); +#endif #endif #ifndef REMAINDER_IS_ALREADY_CALCULATED @@ -289,20 +365,30 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, t2 -= d1; } #else /* !BN_LLONG */ - BN_ULONG t2l,t2h,ql,qh; + BN_ULONG t2l,t2h; q=bn_div_words(n0,n1,d0); +#ifdef BN_DEBUG_LEVITTE + fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\ +X) -> 0x%08X\n", + n0, n1, d0, q); +#endif #ifndef REMAINDER_IS_ALREADY_CALCULATED rem=(n1-q*d0)&BN_MASK2; #endif -#ifdef BN_UMULT_HIGH +#if defined(BN_UMULT_LOHI) + BN_UMULT_LOHI(t2l,t2h,d1,q); +#elif defined(BN_UMULT_HIGH) t2l = d1 * q; t2h = BN_UMULT_HIGH(d1,q); #else + { + BN_ULONG ql, qh; t2l=LBITS(d1); t2h=HBITS(d1); ql =LBITS(q); qh =HBITS(q); mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */ + } #endif for (;;) @@ -320,27 +406,28 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, #endif /* !BN_DIV3W */ l0=bn_mul_words(tmp->d,sdiv->d,div_n,q); - wnum.d--; wnum.top++; tmp->d[div_n]=l0; - for (j=div_n+1; j>0; j--) - if (tmp->d[j-1]) break; - tmp->top=j; - - j=wnum.top; - BN_sub(&wnum,&wnum,tmp); - - snum->top=snum->top+wnum.top-j; - - if (wnum.neg) + wnum.d--; + /* ingore top values of the bignums just sub the two + * BN_ULONG arrays with bn_sub_words */ + if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1)) { + /* Note: As we have considered only the leading + * two BN_ULONGs in the calculation of q, sdiv * q + * might be greater than wnum (but then (q-1) * sdiv + * is less or equal than wnum) + */ q--; - j=wnum.top; - BN_add(&wnum,&wnum,sdiv); - snum->top+=wnum.top-j; + if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n)) + /* we can't have an overflow here (assuming + * that q != 0, but if q == 0 then tmp is + * zero anyway) */ + (*wnump)++; } - *(resp--)=q; - wnump--; + /* store part of the result */ + *resp = q; } + bn_correct_top(snum); if (rm != NULL) { /* Keep a copy of the neg flag in num because if rm==num @@ -350,12 +437,14 @@ int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor, BN_rshift(rm,snum,norm_shift); if (!BN_is_zero(rm)) rm->neg = neg; + bn_check_top(rm); } + if (no_branch) bn_correct_top(res); BN_CTX_end(ctx); return(1); err: + bn_check_top(rm); BN_CTX_end(ctx); return(0); } - #endif