1 /* 2 * Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include <stdio.h> 11 #include "internal/cryptlib.h" 12 #include <openssl/asn1t.h> 13 #include <openssl/bn.h> 14 15 /* 16 * Custom primitive type for BIGNUM handling. This reads in an ASN1_INTEGER 17 * as a BIGNUM directly. Currently it ignores the sign which isn't a problem 18 * since all BIGNUMs used are non negative and anything that looks negative 19 * is normally due to an encoding error. 20 */ 21 22 #define BN_SENSITIVE 1 23 24 static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it); 25 static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it); 26 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it); 27 28 static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, 29 const ASN1_ITEM *it); 30 static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, 31 int utype, char *free_cont, const ASN1_ITEM *it); 32 static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, 33 int utype, char *free_cont, const ASN1_ITEM *it); 34 static int bn_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it, 35 int indent, const ASN1_PCTX *pctx); 36 37 static ASN1_PRIMITIVE_FUNCS bignum_pf = { 38 NULL, 0, 39 bn_new, 40 bn_free, 41 0, 42 bn_c2i, 43 bn_i2c, 44 bn_print 45 }; 46 47 static ASN1_PRIMITIVE_FUNCS cbignum_pf = { 48 NULL, 0, 49 bn_secure_new, 50 bn_free, 51 0, 52 bn_secure_c2i, 53 bn_i2c, 54 bn_print 55 }; 56 57 ASN1_ITEM_start(BIGNUM) 58 ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM" 59 ASN1_ITEM_end(BIGNUM) 60 61 ASN1_ITEM_start(CBIGNUM) 62 ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &cbignum_pf, BN_SENSITIVE, "CBIGNUM" 63 ASN1_ITEM_end(CBIGNUM) 64 65 static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it) 66 { 67 *pval = (ASN1_VALUE *)BN_new(); 68 if (*pval != NULL) 69 return 1; 70 else 71 return 0; 72 } 73 74 static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it) 75 { 76 *pval = (ASN1_VALUE *)BN_secure_new(); 77 if (*pval != NULL) 78 return 1; 79 else 80 return 0; 81 } 82 83 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it) 84 { 85 if (*pval == NULL) 86 return; 87 if (it->size & BN_SENSITIVE) 88 BN_clear_free((BIGNUM *)*pval); 89 else 90 BN_free((BIGNUM *)*pval); 91 *pval = NULL; 92 } 93 94 static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, 95 const ASN1_ITEM *it) 96 { 97 BIGNUM *bn; 98 int pad; 99 if (*pval == NULL) 100 return -1; 101 bn = (BIGNUM *)*pval; 102 /* If MSB set in an octet we need a padding byte */ 103 if (BN_num_bits(bn) & 0x7) 104 pad = 0; 105 else 106 pad = 1; 107 if (cont) { 108 if (pad) 109 *cont++ = 0; 110 BN_bn2bin(bn, cont); 111 } 112 return pad + BN_num_bytes(bn); 113 } 114 115 static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, 116 int utype, char *free_cont, const ASN1_ITEM *it) 117 { 118 BIGNUM *bn; 119 120 if (*pval == NULL && !bn_new(pval, it)) 121 return 0; 122 bn = (BIGNUM *)*pval; 123 if (!BN_bin2bn(cont, len, bn)) { 124 bn_free(pval, it); 125 return 0; 126 } 127 return 1; 128 } 129 130 static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, 131 int utype, char *free_cont, const ASN1_ITEM *it) 132 { 133 int ret; 134 BIGNUM *bn; 135 136 if (*pval == NULL && !bn_secure_new(pval, it)) 137 return 0; 138 139 ret = bn_c2i(pval, cont, len, utype, free_cont, it); 140 if (!ret) 141 return 0; 142 143 /* Set constant-time flag for all secure BIGNUMS */ 144 bn = (BIGNUM *)*pval; 145 BN_set_flags(bn, BN_FLG_CONSTTIME); 146 return ret; 147 } 148 149 static int bn_print(BIO *out, ASN1_VALUE **pval, const ASN1_ITEM *it, 150 int indent, const ASN1_PCTX *pctx) 151 { 152 if (!BN_print(out, *(BIGNUM **)pval)) 153 return 0; 154 if (BIO_puts(out, "\n") <= 0) 155 return 0; 156 return 1; 157 } 158