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SUSE:SLE-12-SP1:GA
compat-openssl098.24732
openssl-CVE-2016-0702.patch
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File openssl-CVE-2016-0702.patch of Package compat-openssl098.24732
From d7a854c055ff22fb7da80c3b0e7cb08d248591d0 Mon Sep 17 00:00:00 2001 From: Andy Polyakov <appro@openssl.org> Date: Tue, 26 Jan 2016 11:34:41 +0100 Subject: [PATCH] bn/bn_exp.c: constant-time MOD_EXP_CTIME_COPY_FROM_PREBUF. Performance penalty varies from platform to platform, and even key length. For rsa2048 sign it was observed to reach almost 10%. CVE-2016-0702 Reviewed-by: Richard Levitte <levitte@openssl.org> --- crypto/bn/bn_exp.c | 75 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 57 insertions(+), 18 deletions(-) Index: openssl-0.9.8j/crypto/bn/bn_exp.c =================================================================== --- openssl-0.9.8j.orig/crypto/bn/bn_exp.c 2016-04-29 14:04:43.807285727 +0200 +++ openssl-0.9.8j/crypto/bn/bn_exp.c 2016-04-29 14:04:47.714344454 +0200 @@ -111,6 +111,7 @@ #include "cryptlib.h" +#include "constant_time_locl.h" #include "bn_lcl.h" /* maximum precomputation table size for *variable* sliding windows */ @@ -521,9 +522,11 @@ err: * as cache lines are concerned. The following functions are used to transfer a BIGNUM * from/to that table. */ -static int MOD_EXP_CTIME_COPY_TO_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int width) +static int MOD_EXP_CTIME_COPY_TO_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int window) { - size_t i, j; + int i, j; + int width = 1 << window; + BN_ULONG *table = (BN_ULONG *)buf; if (bn_wexpand(b, top) == NULL) return 0; @@ -532,26 +535,60 @@ static int MOD_EXP_CTIME_COPY_TO_PREBUF( b->d[b->top++] = 0; } - for (i = 0, j=idx; i < top * sizeof b->d[0]; i++, j+=width) - { - buf[j] = ((unsigned char*)b->d)[i]; + for (i = 0, j = idx; i < top; i++, j += width) { + table[j] = b->d[i]; } bn_correct_top(b); return 1; } -static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int width) +static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, unsigned char *buf, int idx, int window) { - size_t i, j; + int i, j; + int width = 1 << window; + volatile BN_ULONG *table = (volatile BN_ULONG *)buf; if (bn_wexpand(b, top) == NULL) return 0; - for (i=0, j=idx; i < top * sizeof b->d[0]; i++, j+=width) - { - ((unsigned char*)b->d)[i] = buf[j]; - } + if (window <= 3) { + for (i = 0; i < top; i++, table += width) { + BN_ULONG acc = 0; + + for (j = 0; j < width; j++) { + acc |= table[j] & + ((BN_ULONG)0 - (constant_time_eq_int(j,idx)&1)); + } + + b->d[i] = acc; + } + } else { + int xstride = 1 << (window - 2); + BN_ULONG y0, y1, y2, y3; + + i = idx >> (window - 2); /* equivalent of idx / xstride */ + idx &= xstride - 1; /* equivalent of idx % xstride */ + + y0 = (BN_ULONG)0 - (constant_time_eq_int(i,0)&1); + y1 = (BN_ULONG)0 - (constant_time_eq_int(i,1)&1); + y2 = (BN_ULONG)0 - (constant_time_eq_int(i,2)&1); + y3 = (BN_ULONG)0 - (constant_time_eq_int(i,3)&1); + + for (i = 0; i < top; i++, table += width) { + BN_ULONG acc = 0; + + for (j = 0; j < xstride; j++) { + acc |= ( (table[j + 0 * xstride] & y0) | + (table[j + 1 * xstride] & y1) | + (table[j + 2 * xstride] & y2) | + (table[j + 3 * xstride] & y3) ) + & ((BN_ULONG)0 - (constant_time_eq_int(j,idx)&1)); + } + + b->d[i] = acc; + } + } b->top = top; bn_correct_top(b); @@ -635,7 +672,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr * once each for a^0 and intermediate result. */ if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err; - if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, top, powerbuf, 0, numPowers)) goto err; + if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, top, powerbuf, 0, window)) goto err; /* Initialize computeTemp as a^1 with montgomery precalcs */ computeTemp = BN_CTX_get(ctx); @@ -652,7 +689,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr aa=a; if (!BN_to_montgomery(am,aa,mont,ctx)) goto err; if (!BN_copy(computeTemp, am)) goto err; - if (!MOD_EXP_CTIME_COPY_TO_PREBUF(am, top, powerbuf, 1, numPowers)) goto err; + if (!MOD_EXP_CTIME_COPY_TO_PREBUF(am, top, powerbuf, 1, window)) goto err; /* If the window size is greater than 1, then calculate * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1) @@ -666,7 +703,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr /* Calculate a^i = a^(i-1) * a */ if (!BN_mod_mul_montgomery(computeTemp,am,computeTemp,mont,ctx)) goto err; - if (!MOD_EXP_CTIME_COPY_TO_PREBUF(computeTemp, top, powerbuf, i, numPowers)) goto err; + if (!MOD_EXP_CTIME_COPY_TO_PREBUF(computeTemp, top, powerbuf, i, window)) goto err; } } @@ -699,7 +736,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr } /* Fetch the appropriate pre-computed value from the pre-buf */ - if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(computeTemp, top, powerbuf, wvalue, numPowers)) goto err; + if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(computeTemp, top, powerbuf, wvalue, window)) goto err; /* Multiply the result into the intermediate result */ if (!BN_mod_mul_montgomery(r,r,computeTemp,mont,ctx)) goto err; Index: openssl-0.9.8j/crypto/constant_time_locl.h =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ openssl-0.9.8j/crypto/constant_time_locl.h 2016-04-29 14:05:52.974325511 +0200 @@ -0,0 +1,211 @@ +/* crypto/constant_time_locl.h */ +/*- + * Utilities for constant-time cryptography. + * + * Author: Emilia Kasper (emilia@openssl.org) + * Based on previous work by Bodo Moeller, Emilia Kasper, Adam Langley + * (Google). + * ==================================================================== + * Copyright (c) 2014 The OpenSSL Project. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * "This product includes cryptographic software written by + * Eric Young (eay@cryptsoft.com)" + * The word 'cryptographic' can be left out if the rouines from the library + * being used are not cryptographic related :-). + * 4. If you include any Windows specific code (or a derivative thereof) from + * the apps directory (application code) you must include an acknowledgement: + * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" + * + * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * The licence and distribution terms for any publically available version or + * derivative of this code cannot be changed. i.e. this code cannot simply be + * copied and put under another distribution licence + * [including the GNU Public Licence.] + */ + +#ifndef HEADER_CONSTANT_TIME_LOCL_H +# define HEADER_CONSTANT_TIME_LOCL_H + +# include "e_os.h" /* For 'inline' */ + +#ifdef __cplusplus +extern "C" { +#endif + +/*- + * The boolean methods return a bitmask of all ones (0xff...f) for true + * and 0 for false. This is useful for choosing a value based on the result + * of a conditional in constant time. For example, + * + * if (a < b) { + * c = a; + * } else { + * c = b; + * } + * + * can be written as + * + * unsigned int lt = constant_time_lt(a, b); + * c = constant_time_select(lt, a, b); + */ + +/* + * Returns the given value with the MSB copied to all the other + * bits. Uses the fact that arithmetic shift shifts-in the sign bit. + * However, this is not ensured by the C standard so you may need to + * replace this with something else on odd CPUs. + */ +static inline unsigned int constant_time_msb(unsigned int a); + +/* + * Returns 0xff..f if a < b and 0 otherwise. + */ +static inline unsigned int constant_time_lt(unsigned int a, unsigned int b); +/* Convenience method for getting an 8-bit mask. */ +static inline unsigned char constant_time_lt_8(unsigned int a, + unsigned int b); + +/* + * Returns 0xff..f if a >= b and 0 otherwise. + */ +static inline unsigned int constant_time_ge(unsigned int a, unsigned int b); +/* Convenience method for getting an 8-bit mask. */ +static inline unsigned char constant_time_ge_8(unsigned int a, + unsigned int b); + +/* + * Returns 0xff..f if a == 0 and 0 otherwise. + */ +static inline unsigned int constant_time_is_zero(unsigned int a); +/* Convenience method for getting an 8-bit mask. */ +static inline unsigned char constant_time_is_zero_8(unsigned int a); + +/* + * Returns 0xff..f if a == b and 0 otherwise. + */ +static inline unsigned int constant_time_eq(unsigned int a, unsigned int b); +/* Convenience method for getting an 8-bit mask. */ +static inline unsigned char constant_time_eq_8(unsigned int a, + unsigned int b); +/* Signed integers. */ +static inline unsigned int constant_time_eq_int(int a, int b); +/* Convenience method for getting an 8-bit mask. */ +static inline unsigned char constant_time_eq_int_8(int a, int b); + +/*- + * Returns (mask & a) | (~mask & b). + * + * When |mask| is all 1s or all 0s (as returned by the methods above), + * the select methods return either |a| (if |mask| is nonzero) or |b| + * (if |mask| is zero). + */ +static inline unsigned int constant_time_select(unsigned int mask, + unsigned int a, + unsigned int b); +/* Convenience method for unsigned chars. */ +static inline unsigned char constant_time_select_8(unsigned char mask, + unsigned char a, + unsigned char b); +/* Convenience method for signed integers. */ +static inline int constant_time_select_int(unsigned int mask, int a, int b); + +static inline unsigned int constant_time_msb(unsigned int a) +{ + return 0 - (a >> (sizeof(a) * 8 - 1)); +} + +static inline unsigned int constant_time_lt(unsigned int a, unsigned int b) +{ + return constant_time_msb(a ^ ((a ^ b) | ((a - b) ^ b))); +} + +static inline unsigned char constant_time_lt_8(unsigned int a, unsigned int b) +{ + return (unsigned char)(constant_time_lt(a, b)); +} + +static inline unsigned int constant_time_ge(unsigned int a, unsigned int b) +{ + return ~constant_time_lt(a, b); +} + +static inline unsigned char constant_time_ge_8(unsigned int a, unsigned int b) +{ + return (unsigned char)(constant_time_ge(a, b)); +} + +static inline unsigned int constant_time_is_zero(unsigned int a) +{ + return constant_time_msb(~a & (a - 1)); +} + +static inline unsigned char constant_time_is_zero_8(unsigned int a) +{ + return (unsigned char)(constant_time_is_zero(a)); +} + +static inline unsigned int constant_time_eq(unsigned int a, unsigned int b) +{ + return constant_time_is_zero(a ^ b); +} + +static inline unsigned char constant_time_eq_8(unsigned int a, unsigned int b) +{ + return (unsigned char)(constant_time_eq(a, b)); +} + +static inline unsigned int constant_time_eq_int(int a, int b) +{ + return constant_time_eq((unsigned)(a), (unsigned)(b)); +} + +static inline unsigned char constant_time_eq_int_8(int a, int b) +{ + return constant_time_eq_8((unsigned)(a), (unsigned)(b)); +} + +static inline unsigned int constant_time_select(unsigned int mask, + unsigned int a, + unsigned int b) +{ + return (mask & a) | (~mask & b); +} + +static inline unsigned char constant_time_select_8(unsigned char mask, + unsigned char a, + unsigned char b) +{ + return (unsigned char)(constant_time_select(mask, a, b)); +} + +static inline int constant_time_select_int(unsigned int mask, int a, int b) +{ + return (int)(constant_time_select(mask, (unsigned)(a), (unsigned)(b))); +} + +#ifdef __cplusplus +} +#endif + +#endif /* HEADER_CONSTANT_TIME_LOCL_H */
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