+++ /dev/null
-/*
- * Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
- *
- * Licensed under the Apache License 2.0 (the "License"). You may not use
- * this file except in compliance with the License. You can obtain a copy
- * in the file LICENSE in the source distribution or at
- * https://www.openssl.org/source/license.html
- */
-
-#include <openssl/e_os2.h>
-#include <stddef.h>
-#include <sys/types.h>
-#include <string.h>
-#include <openssl/bn.h>
-#include <openssl/err.h>
-#include <openssl/rsaerr.h>
-#include "internal/endian.h"
-#include "internal/numbers.h"
-#include "internal/constant_time.h"
-#include "bn_local.h"
-
-# if BN_BYTES == 8
-typedef uint64_t limb_t;
-# if defined(__SIZEOF_INT128__) && __SIZEOF_INT128__ == 16
-typedef uint128_t limb2_t;
-# define HAVE_LIMB2_T
-# endif
-# define LIMB_BIT_SIZE 64
-# define LIMB_BYTE_SIZE 8
-# elif BN_BYTES == 4
-typedef uint32_t limb_t;
-typedef uint64_t limb2_t;
-# define LIMB_BIT_SIZE 32
-# define LIMB_BYTE_SIZE 4
-# define HAVE_LIMB2_T
-# else
-# error "Not supported"
-# endif
-
-/*
- * For multiplication we're using schoolbook multiplication,
- * so if we have two numbers, each with 6 "digits" (words)
- * the multiplication is calculated as follows:
- * A B C D E F
- * x I J K L M N
- * --------------
- * N*F
- * N*E
- * N*D
- * N*C
- * N*B
- * N*A
- * M*F
- * M*E
- * M*D
- * M*C
- * M*B
- * M*A
- * L*F
- * L*E
- * L*D
- * L*C
- * L*B
- * L*A
- * K*F
- * K*E
- * K*D
- * K*C
- * K*B
- * K*A
- * J*F
- * J*E
- * J*D
- * J*C
- * J*B
- * J*A
- * I*F
- * I*E
- * I*D
- * I*C
- * I*B
- * + I*A
- * ==========================
- * N*B N*D N*F
- * + N*A N*C N*E
- * + M*B M*D M*F
- * + M*A M*C M*E
- * + L*B L*D L*F
- * + L*A L*C L*E
- * + K*B K*D K*F
- * + K*A K*C K*E
- * + J*B J*D J*F
- * + J*A J*C J*E
- * + I*B I*D I*F
- * + I*A I*C I*E
- *
- * 1+1 1+3 1+5
- * 1+0 1+2 1+4
- * 0+1 0+3 0+5
- * 0+0 0+2 0+4
- *
- * 0 1 2 3 4 5 6
- * which requires n^2 multiplications and 2n full length additions
- * as we can keep every other result of limb multiplication in two separate
- * limbs
- */
-
-#if defined HAVE_LIMB2_T
-static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b)
-{
- limb2_t t;
- /*
- * this is idiomatic code to tell compiler to use the native mul
- * those three lines will actually compile to single instruction
- */
-
- t = (limb2_t)a * b;
- *hi = t >> LIMB_BIT_SIZE;
- *lo = (limb_t)t;
-}
-#elif (BN_BYTES == 8) && (defined _MSC_VER)
-# if defined(_M_X64)
-/*
- * on x86_64 (x64) we can use the _umul128 intrinsic to get one `mul`
- * instruction to get both high and low 64 bits of the multiplication.
- * https://learn.microsoft.com/en-us/cpp/intrinsics/umul128?view=msvc-140
- */
-#include <intrin.h>
-#pragma intrinsic(_umul128)
-static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b)
-{
- *lo = _umul128(a, b, hi);
-}
-# elif defined(_M_ARM64) || defined (_M_IA64)
-/*
- * We can't use the __umulh() on x86_64 as then msvc generates two `mul`
- * instructions; so use this more portable intrinsic on platforms that
- * don't support _umul128 (like aarch64 (ARM64) or ia64)
- * https://learn.microsoft.com/en-us/cpp/intrinsics/umulh?view=msvc-140
- */
-#include <intrin.h>
-static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b)
-{
- *lo = a * b;
- *hi = __umulh(a, b);
-}
-# else
-# error Only x64, ARM64 and IA64 supported.
-# endif /* defined(_M_X64) */
-#else
-/*
- * if the compiler doesn't have either a 128bit data type nor a "return
- * high 64 bits of multiplication"
- */
-static ossl_inline void _mul_limb(limb_t *hi, limb_t *lo, limb_t a, limb_t b)
-{
- limb_t a_low = (limb_t)(uint32_t)a;
- limb_t a_hi = a >> 32;
- limb_t b_low = (limb_t)(uint32_t)b;
- limb_t b_hi = b >> 32;
-
- limb_t p0 = a_low * b_low;
- limb_t p1 = a_low * b_hi;
- limb_t p2 = a_hi * b_low;
- limb_t p3 = a_hi * b_hi;
-
- uint32_t cy = (uint32_t)(((p0 >> 32) + (uint32_t)p1 + (uint32_t)p2) >> 32);
-
- *lo = p0 + (p1 << 32) + (p2 << 32);
- *hi = p3 + (p1 >> 32) + (p2 >> 32) + cy;
-}
-#endif
-
-/* add two limbs with carry in, return carry out */
-static ossl_inline limb_t _add_limb(limb_t *ret, limb_t a, limb_t b, limb_t carry)
-{
- limb_t carry1, carry2, t;
- /*
- * `c = a + b; if (c < a)` is idiomatic code that makes compilers
- * use add with carry on assembly level
- */
-
- *ret = a + carry;
- if (*ret < a)
- carry1 = 1;
- else
- carry1 = 0;
-
- t = *ret;
- *ret = t + b;
- if (*ret < t)
- carry2 = 1;
- else
- carry2 = 0;
-
- return carry1 + carry2;
-}
-
-/*
- * add two numbers of the same size, return overflow
- *
- * add a to b, place result in ret; all arrays need to be n limbs long
- * return overflow from addition (0 or 1)
- */
-static ossl_inline limb_t add(limb_t *ret, limb_t *a, limb_t *b, size_t n)
-{
- limb_t c = 0;
- ossl_ssize_t i;
-
- for(i = n - 1; i > -1; i--)
- c = _add_limb(&ret[i], a[i], b[i], c);
-
- return c;
-}
-
-/*
- * return number of limbs necessary for temporary values
- * when multiplying numbers n limbs large
- */
-static ossl_inline size_t mul_limb_numb(size_t n)
-{
- return 2 * n * 2;
-}
-
-/*
- * multiply two numbers of the same size
- *
- * multiply a by b, place result in ret; a and b need to be n limbs long
- * ret needs to be 2*n limbs long, tmp needs to be mul_limb_numb(n) limbs
- * long
- */
-static void limb_mul(limb_t *ret, limb_t *a, limb_t *b, size_t n, limb_t *tmp)
-{
- limb_t *r_odd, *r_even;
- size_t i, j, k;
-
- r_odd = tmp;
- r_even = &tmp[2 * n];
-
- memset(ret, 0, 2 * n * sizeof(limb_t));
-
- for (i = 0; i < n; i++) {
- for (k = 0; k < i + n + 1; k++) {
- r_even[k] = 0;
- r_odd[k] = 0;
- }
- for (j = 0; j < n; j++) {
- /*
- * place results from even and odd limbs in separate arrays so that
- * we don't have to calculate overflow every time we get individual
- * limb multiplication result
- */
- if (j % 2 == 0)
- _mul_limb(&r_even[i + j], &r_even[i + j + 1], a[i], b[j]);
- else
- _mul_limb(&r_odd[i + j], &r_odd[i + j + 1], a[i], b[j]);
- }
- /*
- * skip the least significant limbs when adding multiples of
- * more significant limbs (they're zero anyway)
- */
- add(ret, ret, r_even, n + i + 1);
- add(ret, ret, r_odd, n + i + 1);
- }
-}
-
-/* modifies the value in place by performing a right shift by one bit */
-static ossl_inline void rshift1(limb_t *val, size_t n)
-{
- limb_t shift_in = 0, shift_out = 0;
- size_t i;
-
- for (i = 0; i < n; i++) {
- shift_out = val[i] & 1;
- val[i] = shift_in << (LIMB_BIT_SIZE - 1) | (val[i] >> 1);
- shift_in = shift_out;
- }
-}
-
-/* extend the LSB of flag to all bits of limb */
-static ossl_inline limb_t mk_mask(limb_t flag)
-{
- flag |= flag << 1;
- flag |= flag << 2;
- flag |= flag << 4;
- flag |= flag << 8;
- flag |= flag << 16;
-#if (LIMB_BYTE_SIZE == 8)
- flag |= flag << 32;
-#endif
- return flag;
-}
-
-/*
- * copy from either a or b to ret based on flag
- * when flag == 0, then copies from b
- * when flag == 1, then copies from a
- */
-static ossl_inline void cselect(limb_t flag, limb_t *ret, limb_t *a, limb_t *b, size_t n)
-{
- /*
- * would be more efficient with non volatile mask, but then gcc
- * generates code with jumps
- */
- volatile limb_t mask;
- size_t i;
-
- mask = mk_mask(flag);
- for (i = 0; i < n; i++) {
-#if (LIMB_BYTE_SIZE == 8)
- ret[i] = constant_time_select_64(mask, a[i], b[i]);
-#else
- ret[i] = constant_time_select_32(mask, a[i], b[i]);
-#endif
- }
-}
-
-static limb_t _sub_limb(limb_t *ret, limb_t a, limb_t b, limb_t borrow)
-{
- limb_t borrow1, borrow2, t;
- /*
- * while it doesn't look constant-time, this is idiomatic code
- * to tell compilers to use the carry bit from subtraction
- */
-
- *ret = a - borrow;
- if (*ret > a)
- borrow1 = 1;
- else
- borrow1 = 0;
-
- t = *ret;
- *ret = t - b;
- if (*ret > t)
- borrow2 = 1;
- else
- borrow2 = 0;
-
- return borrow1 + borrow2;
-}
-
-/*
- * place the result of a - b into ret, return the borrow bit.
- * All arrays need to be n limbs long
- */
-static limb_t sub(limb_t *ret, limb_t *a, limb_t *b, size_t n)
-{
- limb_t borrow = 0;
- ossl_ssize_t i;
-
- for (i = n - 1; i > -1; i--)
- borrow = _sub_limb(&ret[i], a[i], b[i], borrow);
-
- return borrow;
-}
-
-/* return the number of limbs necessary to allocate for the mod() tmp operand */
-static ossl_inline size_t mod_limb_numb(size_t anum, size_t modnum)
-{
- return (anum + modnum) * 3;
-}
-
-/*
- * calculate a % mod, place the result in ret
- * size of a is defined by anum, size of ret and mod is modnum,
- * size of tmp is returned by mod_limb_numb()
- */
-static void mod(limb_t *ret, limb_t *a, size_t anum, limb_t *mod,
- size_t modnum, limb_t *tmp)
-{
- limb_t *atmp, *modtmp, *rettmp;
- limb_t res;
- size_t i;
-
- memset(tmp, 0, mod_limb_numb(anum, modnum) * LIMB_BYTE_SIZE);
-
- atmp = tmp;
- modtmp = &tmp[anum + modnum];
- rettmp = &tmp[(anum + modnum) * 2];
-
- for (i = modnum; i <modnum + anum; i++)
- atmp[i] = a[i-modnum];
-
- for (i = 0; i < modnum; i++)
- modtmp[i] = mod[i];
-
- for (i = 0; i < anum * LIMB_BIT_SIZE; i++) {
- rshift1(modtmp, anum + modnum);
- res = sub(rettmp, atmp, modtmp, anum+modnum);
- cselect(res, atmp, atmp, rettmp, anum+modnum);
- }
-
- memcpy(ret, &atmp[anum], sizeof(limb_t) * modnum);
-}
-
-/* necessary size of tmp for a _mul_add_limb() call with provided anum */
-static ossl_inline size_t _mul_add_limb_numb(size_t anum)
-{
- return 2 * (anum + 1);
-}
-
-/* multiply a by m, add to ret, return carry */
-static limb_t _mul_add_limb(limb_t *ret, limb_t *a, size_t anum,
- limb_t m, limb_t *tmp)
-{
- limb_t carry = 0;
- limb_t *r_odd, *r_even;
- size_t i;
-
- memset(tmp, 0, sizeof(limb_t) * (anum + 1) * 2);
-
- r_odd = tmp;
- r_even = &tmp[anum + 1];
-
- for (i = 0; i < anum; i++) {
- /*
- * place the results from even and odd limbs in separate arrays
- * so that we have to worry about carry just once
- */
- if (i % 2 == 0)
- _mul_limb(&r_even[i], &r_even[i + 1], a[i], m);
- else
- _mul_limb(&r_odd[i], &r_odd[i + 1], a[i], m);
- }
- /* assert: add() carry here will be equal zero */
- add(r_even, r_even, r_odd, anum + 1);
- /*
- * while here it will not overflow as the max value from multiplication
- * is -2 while max overflow from addition is 1, so the max value of
- * carry is -1 (i.e. max int)
- */
- carry = add(ret, ret, &r_even[1], anum) + r_even[0];
-
- return carry;
-}
-
-static ossl_inline size_t mod_montgomery_limb_numb(size_t modnum)
-{
- return modnum * 2 + _mul_add_limb_numb(modnum);
-}
-
-/*
- * calculate a % mod, place result in ret
- * assumes that a is in Montgomery form with the R (Montgomery modulus) being
- * smallest power of two big enough to fit mod and that's also a power
- * of the count of number of bits in limb_t (B).
- * For calculation, we also need n', such that mod * n' == -1 mod B.
- * anum must be <= 2 * modnum
- * ret needs to be modnum words long
- * tmp needs to be mod_montgomery_limb_numb(modnum) limbs long
- */
-static void mod_montgomery(limb_t *ret, limb_t *a, size_t anum, limb_t *mod,
- size_t modnum, limb_t ni0, limb_t *tmp)
-{
- limb_t carry, v;
- limb_t *res, *rp, *tmp2;
- ossl_ssize_t i;
-
- res = tmp;
- /*
- * for intermediate result we need an integer twice as long as modulus
- * but keep the input in the least significant limbs
- */
- memset(res, 0, sizeof(limb_t) * (modnum * 2));
- memcpy(&res[modnum * 2 - anum], a, sizeof(limb_t) * anum);
- rp = &res[modnum];
- tmp2 = &res[modnum * 2];
-
- carry = 0;
-
- /* add multiples of the modulus to the value until R divides it cleanly */
- for (i = modnum; i > 0; i--, rp--) {
- v = _mul_add_limb(rp, mod, modnum, rp[modnum-1] * ni0, tmp2);
- v = v + carry + rp[-1];
- carry |= (v != rp[-1]);
- carry &= (v <= rp[-1]);
- rp[-1] = v;
- }
-
- /* perform the final reduction by mod... */
- carry -= sub(ret, rp, mod, modnum);
-
- /* ...conditionally */
- cselect(carry, ret, rp, ret, modnum);
-}
-
-/* allocated buffer should be freed afterwards */
-static void BN_to_limb(const BIGNUM *bn, limb_t *buf, size_t limbs)
-{
- int i;
- int real_limbs = (BN_num_bytes(bn) + LIMB_BYTE_SIZE - 1) / LIMB_BYTE_SIZE;
- limb_t *ptr = buf + (limbs - real_limbs);
-
- for (i = 0; i < real_limbs; i++)
- ptr[i] = bn->d[real_limbs - i - 1];
-}
-
-#if LIMB_BYTE_SIZE == 8
-static ossl_inline uint64_t be64(uint64_t host)
-{
- uint64_t big = 0;
- DECLARE_IS_ENDIAN;
-
- if (!IS_LITTLE_ENDIAN)
- return host;
-
- big |= (host & 0xff00000000000000) >> 56;
- big |= (host & 0x00ff000000000000) >> 40;
- big |= (host & 0x0000ff0000000000) >> 24;
- big |= (host & 0x000000ff00000000) >> 8;
- big |= (host & 0x00000000ff000000) << 8;
- big |= (host & 0x0000000000ff0000) << 24;
- big |= (host & 0x000000000000ff00) << 40;
- big |= (host & 0x00000000000000ff) << 56;
- return big;
-}
-
-#else
-/* Not all platforms have htobe32(). */
-static ossl_inline uint32_t be32(uint32_t host)
-{
- uint32_t big = 0;
- DECLARE_IS_ENDIAN;
-
- if (!IS_LITTLE_ENDIAN)
- return host;
-
- big |= (host & 0xff000000) >> 24;
- big |= (host & 0x00ff0000) >> 8;
- big |= (host & 0x0000ff00) << 8;
- big |= (host & 0x000000ff) << 24;
- return big;
-}
-#endif
-
-/*
- * We assume that intermediate, possible_arg2, blinding, and ctx are used
- * similar to BN_BLINDING_invert_ex() arguments.
- * to_mod is RSA modulus.
- * buf and num is the serialization buffer and its length.
- *
- * Here we use classic/Montgomery multiplication and modulo. After the calculation finished
- * we serialize the new structure instead of BIGNUMs taking endianness into account.
- */
-int ossl_bn_rsa_do_unblind(const BIGNUM *intermediate,
- const BN_BLINDING *blinding,
- const BIGNUM *possible_arg2,
- const BIGNUM *to_mod, BN_CTX *ctx,
- unsigned char *buf, int num)
-{
- limb_t *l_im = NULL, *l_mul = NULL, *l_mod = NULL;
- limb_t *l_ret = NULL, *l_tmp = NULL, l_buf;
- size_t l_im_count = 0, l_mul_count = 0, l_size = 0, l_mod_count = 0;
- size_t l_tmp_count = 0;
- int ret = 0;
- size_t i;
- unsigned char *tmp;
- const BIGNUM *arg1 = intermediate;
- const BIGNUM *arg2 = (possible_arg2 == NULL) ? blinding->Ai : possible_arg2;
-
- l_im_count = (BN_num_bytes(arg1) + LIMB_BYTE_SIZE - 1) / LIMB_BYTE_SIZE;
- l_mul_count = (BN_num_bytes(arg2) + LIMB_BYTE_SIZE - 1) / LIMB_BYTE_SIZE;
- l_mod_count = (BN_num_bytes(to_mod) + LIMB_BYTE_SIZE - 1) / LIMB_BYTE_SIZE;
-
- l_size = l_im_count > l_mul_count ? l_im_count : l_mul_count;
- l_im = OPENSSL_zalloc(l_size * LIMB_BYTE_SIZE);
- l_mul = OPENSSL_zalloc(l_size * LIMB_BYTE_SIZE);
- l_mod = OPENSSL_zalloc(l_mod_count * LIMB_BYTE_SIZE);
-
- if ((l_im == NULL) || (l_mul == NULL) || (l_mod == NULL))
- goto err;
-
- BN_to_limb(arg1, l_im, l_size);
- BN_to_limb(arg2, l_mul, l_size);
- BN_to_limb(to_mod, l_mod, l_mod_count);
-
- l_ret = OPENSSL_malloc(2 * l_size * LIMB_BYTE_SIZE);
-
- if (blinding->m_ctx != NULL) {
- l_tmp_count = mul_limb_numb(l_size) > mod_montgomery_limb_numb(l_mod_count) ?
- mul_limb_numb(l_size) : mod_montgomery_limb_numb(l_mod_count);
- l_tmp = OPENSSL_malloc(l_tmp_count * LIMB_BYTE_SIZE);
- } else {
- l_tmp_count = mul_limb_numb(l_size) > mod_limb_numb(2 * l_size, l_mod_count) ?
- mul_limb_numb(l_size) : mod_limb_numb(2 * l_size, l_mod_count);
- l_tmp = OPENSSL_malloc(l_tmp_count * LIMB_BYTE_SIZE);
- }
-
- if ((l_ret == NULL) || (l_tmp == NULL))
- goto err;
-
- if (blinding->m_ctx != NULL) {
- limb_mul(l_ret, l_im, l_mul, l_size, l_tmp);
- mod_montgomery(l_ret, l_ret, 2 * l_size, l_mod, l_mod_count,
- blinding->m_ctx->n0[0], l_tmp);
- } else {
- limb_mul(l_ret, l_im, l_mul, l_size, l_tmp);
- mod(l_ret, l_ret, 2 * l_size, l_mod, l_mod_count, l_tmp);
- }
-
- /* modulus size in bytes can be equal to num but after limbs conversion it becomes bigger */
- if (num < BN_num_bytes(to_mod)) {
- ERR_raise(ERR_LIB_BN, ERR_R_PASSED_INVALID_ARGUMENT);
- goto err;
- }
-
- memset(buf, 0, num);
- tmp = buf + num - BN_num_bytes(to_mod);
- for (i = 0; i < l_mod_count; i++) {
-#if LIMB_BYTE_SIZE == 8
- l_buf = be64(l_ret[i]);
-#else
- l_buf = be32(l_ret[i]);
-#endif
- if (i == 0) {
- int delta = LIMB_BYTE_SIZE - ((l_mod_count * LIMB_BYTE_SIZE) - num);
-
- memcpy(tmp, ((char *)&l_buf) + LIMB_BYTE_SIZE - delta, delta);
- tmp += delta;
- } else {
- memcpy(tmp, &l_buf, LIMB_BYTE_SIZE);
- tmp += LIMB_BYTE_SIZE;
- }
- }
- ret = num;
-
- err:
- OPENSSL_free(l_im);
- OPENSSL_free(l_mul);
- OPENSSL_free(l_mod);
- OPENSSL_free(l_tmp);
- OPENSSL_free(l_ret);
-
- return ret;
-}
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