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openssl/SOURCES/0102-CVE-2022-4304-RSA-time...

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From 8e257b86e5812c6e1cfa9e8e5f5660ac7bed899d Mon Sep 17 00:00:00 2001
From: Dmitry Belyavskiy <beldmit@gmail.com>
Date: Fri, 20 Jan 2023 15:03:40 +0000
Subject: [PATCH 03/18] Fix Timing Oracle in RSA decryption
A timing based side channel exists in the OpenSSL RSA Decryption
implementation which could be sufficient to recover a plaintext across
a network in a Bleichenbacher style attack. To achieve a successful
decryption an attacker would have to be able to send a very large number
of trial messages for decryption. The vulnerability affects all RSA
padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE.
Patch written by Dmitry Belyavsky and Hubert Kario
CVE-2022-4304
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
---
crypto/bn/bn_blind.c | 14 -
crypto/bn/bn_local.h | 14 +
crypto/bn/build.info | 2 +-
crypto/bn/rsa_sup_mul.c | 604 ++++++++++++++++++++++++++++++++++++++++
crypto/rsa/rsa_ossl.c | 19 +-
include/crypto/bn.h | 6 +
6 files changed, 638 insertions(+), 21 deletions(-)
create mode 100644 crypto/bn/rsa_sup_mul.c
diff --git a/crypto/bn/bn_blind.c b/crypto/bn/bn_blind.c
index 72457b34cf..6061ebb4c0 100644
--- a/crypto/bn/bn_blind.c
+++ b/crypto/bn/bn_blind.c
@@ -13,20 +13,6 @@
#define BN_BLINDING_COUNTER 32
-struct bn_blinding_st {
- BIGNUM *A;
- BIGNUM *Ai;
- BIGNUM *e;
- BIGNUM *mod; /* just a reference */
- CRYPTO_THREAD_ID tid;
- int counter;
- unsigned long flags;
- BN_MONT_CTX *m_ctx;
- int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
- const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
- CRYPTO_RWLOCK *lock;
-};
-
BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
{
BN_BLINDING *ret = NULL;
diff --git a/crypto/bn/bn_local.h b/crypto/bn/bn_local.h
index c9a7ecf298..8c428f919d 100644
--- a/crypto/bn/bn_local.h
+++ b/crypto/bn/bn_local.h
@@ -290,6 +290,20 @@ struct bn_gencb_st {
} cb;
};
+struct bn_blinding_st {
+ BIGNUM *A;
+ BIGNUM *Ai;
+ BIGNUM *e;
+ BIGNUM *mod; /* just a reference */
+ CRYPTO_THREAD_ID tid;
+ int counter;
+ unsigned long flags;
+ BN_MONT_CTX *m_ctx;
+ int (*bn_mod_exp) (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
+ const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
+ CRYPTO_RWLOCK *lock;
+};
+
/*-
* BN_window_bits_for_exponent_size -- macro for sliding window mod_exp functions
*
diff --git a/crypto/bn/build.info b/crypto/bn/build.info
index c4ba51b265..f4ff619239 100644
--- a/crypto/bn/build.info
+++ b/crypto/bn/build.info
@@ -105,7 +105,7 @@ $COMMON=bn_add.c bn_div.c bn_exp.c bn_lib.c bn_ctx.c bn_mul.c \
bn_mod.c bn_conv.c bn_rand.c bn_shift.c bn_word.c bn_blind.c \
bn_kron.c bn_sqrt.c bn_gcd.c bn_prime.c bn_sqr.c \
bn_recp.c bn_mont.c bn_mpi.c bn_exp2.c bn_gf2m.c bn_nist.c \
- bn_intern.c bn_dh.c bn_rsa_fips186_4.c bn_const.c
+ bn_intern.c bn_dh.c bn_rsa_fips186_4.c bn_const.c rsa_sup_mul.c
SOURCE[../../libcrypto]=$COMMON $BNASM bn_print.c bn_err.c bn_srp.c
DEFINE[../../libcrypto]=$BNDEF
IF[{- !$disabled{'deprecated-0.9.8'} -}]
diff --git a/crypto/bn/rsa_sup_mul.c b/crypto/bn/rsa_sup_mul.c
new file mode 100644
index 0000000000..0e0d02e194
--- /dev/null
+++ b/crypto/bn/rsa_sup_mul.c
@@ -0,0 +1,604 @@
+#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)
+/* https://learn.microsoft.com/en-us/cpp/intrinsics/umul128?view=msvc-170 */
+#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);
+}
+#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;
+}
diff --git a/crypto/rsa/rsa_ossl.c b/crypto/rsa/rsa_ossl.c
index 381c659352..7e8b791fba 100644
--- a/crypto/rsa/rsa_ossl.c
+++ b/crypto/rsa/rsa_ossl.c
@@ -469,13 +469,20 @@ static int rsa_ossl_private_decrypt(int flen, const unsigned char *from,
BN_free(d);
}
- if (blinding)
- if (!rsa_blinding_invert(blinding, ret, unblind, ctx))
+ if (blinding) {
+ /*
+ * ossl_bn_rsa_do_unblind() combines blinding inversion and
+ * 0-padded BN BE serialization
+ */
+ j = ossl_bn_rsa_do_unblind(ret, blinding, unblind, rsa->n, ctx,
+ buf, num);
+ if (j == 0)
goto err;
-
- j = BN_bn2binpad(ret, buf, num);
- if (j < 0)
- goto err;
+ } else {
+ j = BN_bn2binpad(ret, buf, num);
+ if (j < 0)
+ goto err;
+ }
switch (padding) {
case RSA_PKCS1_PADDING:
diff --git a/include/crypto/bn.h b/include/crypto/bn.h
index cf69bea848..cd45654210 100644
--- a/include/crypto/bn.h
+++ b/include/crypto/bn.h
@@ -114,4 +114,10 @@ OSSL_LIB_CTX *ossl_bn_get_libctx(BN_CTX *ctx);
extern const BIGNUM ossl_bn_inv_sqrt_2;
+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);
+
#endif
--
2.39.1
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