2f18596c32
This commit addresses multiple side-channel vulnerabilities present during RSA key validation. Private key parameters are re-computed using variable-time functions. This issue was discovered and reported by the NISEC group at TAU Finland. Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/9779)
157 lines
4 KiB
C
157 lines
4 KiB
C
/*
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* Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <stdio.h>
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#include "internal/cryptlib.h"
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#include <openssl/asn1t.h>
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#include <openssl/bn.h>
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/*
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* Custom primitive type for BIGNUM handling. This reads in an ASN1_INTEGER
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* as a BIGNUM directly. Currently it ignores the sign which isn't a problem
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* since all BIGNUMs used are non negative and anything that looks negative
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* is normally due to an encoding error.
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*/
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#define BN_SENSITIVE 1
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static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
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static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
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static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it);
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static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
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const ASN1_ITEM *it);
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static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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int utype, char *free_cont, const ASN1_ITEM *it);
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static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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int utype, char *free_cont, const ASN1_ITEM *it);
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static int bn_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
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int indent, const ASN1_PCTX *pctx);
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static ASN1_PRIMITIVE_FUNCS bignum_pf = {
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NULL, 0,
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bn_new,
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bn_free,
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0,
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bn_c2i,
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bn_i2c,
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bn_print
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};
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static ASN1_PRIMITIVE_FUNCS cbignum_pf = {
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NULL, 0,
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bn_secure_new,
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bn_free,
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0,
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bn_secure_c2i,
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bn_i2c,
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bn_print
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};
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ASN1_ITEM_start(BIGNUM)
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ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM"
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ASN1_ITEM_end(BIGNUM)
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ASN1_ITEM_start(CBIGNUM)
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ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &cbignum_pf, BN_SENSITIVE, "CBIGNUM"
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ASN1_ITEM_end(CBIGNUM)
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static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
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{
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*pval = (ASN1_VALUE *)BN_new();
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if (*pval != NULL)
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return 1;
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else
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return 0;
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}
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static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
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{
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*pval = (ASN1_VALUE *)BN_secure_new();
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if (*pval != NULL)
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return 1;
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else
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return 0;
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}
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static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
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{
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if (!*pval)
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return;
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if (it->size & BN_SENSITIVE)
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BN_clear_free((BIGNUM *)*pval);
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else
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BN_free((BIGNUM *)*pval);
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*pval = NULL;
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}
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static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
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const ASN1_ITEM *it)
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{
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BIGNUM *bn;
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int pad;
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if (!*pval)
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return -1;
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bn = (BIGNUM *)*pval;
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/* If MSB set in an octet we need a padding byte */
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if (BN_num_bits(bn) & 0x7)
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pad = 0;
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else
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pad = 1;
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if (cont) {
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if (pad)
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*cont++ = 0;
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BN_bn2bin(bn, cont);
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}
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return pad + BN_num_bytes(bn);
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}
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static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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int utype, char *free_cont, const ASN1_ITEM *it)
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{
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BIGNUM *bn;
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if (*pval == NULL && !bn_new(pval, it))
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return 0;
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bn = (BIGNUM *)*pval;
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if (!BN_bin2bn(cont, len, bn)) {
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bn_free(pval, it);
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return 0;
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}
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return 1;
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}
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static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
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int utype, char *free_cont, const ASN1_ITEM *it)
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{
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int ret;
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BIGNUM *bn;
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if (!*pval && !bn_secure_new(pval, it))
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return 0;
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ret = bn_c2i(pval, cont, len, utype, free_cont, it);
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if (!ret)
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return 0;
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/* Set constant-time flag for all secure BIGNUMS */
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bn = (BIGNUM *)*pval;
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BN_set_flags(bn, BN_FLG_CONSTTIME);
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return ret;
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}
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static int bn_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it,
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int indent, const ASN1_PCTX *pctx)
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{
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if (!BN_print(out, *(BIGNUM **)pval))
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return 0;
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if (BIO_puts(out, "\n") <= 0)
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return 0;
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return 1;
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}
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