1 /*
2 * Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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(const 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, const 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
ASN1_ITEM_start(BIGNUM)57 ASN1_ITEM_start(BIGNUM)
58 ASN1_ITYPE_PRIMITIVE,
59 V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM" ASN1_ITEM_end(BIGNUM)
60
61 ASN1_ITEM_start(CBIGNUM) ASN1_ITYPE_PRIMITIVE,
62 V_ASN1_INTEGER, NULL, 0, &cbignum_pf, BN_SENSITIVE, "CBIGNUM" ASN1_ITEM_end(CBIGNUM)
63
64 static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
65 {
66 *pval = (ASN1_VALUE *)BN_new();
67 if (*pval != NULL)
68 return 1;
69 else
70 return 0;
71 }
72
bn_secure_new(ASN1_VALUE ** pval,const ASN1_ITEM * it)73 static int bn_secure_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
74 {
75 *pval = (ASN1_VALUE *)BN_secure_new();
76 if (*pval != NULL)
77 return 1;
78 else
79 return 0;
80 }
81
bn_free(ASN1_VALUE ** pval,const ASN1_ITEM * it)82 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
83 {
84 if (*pval == NULL)
85 return;
86 if (it->size & BN_SENSITIVE)
87 BN_clear_free((BIGNUM *)*pval);
88 else
89 BN_free((BIGNUM *)*pval);
90 *pval = NULL;
91 }
92
bn_i2c(const ASN1_VALUE ** pval,unsigned char * cont,int * putype,const ASN1_ITEM * it)93 static int bn_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,
94 const ASN1_ITEM *it)
95 {
96 BIGNUM *bn;
97 int pad;
98 if (*pval == NULL)
99 return -1;
100 bn = (BIGNUM *)*pval;
101 /* If MSB set in an octet we need a padding byte */
102 if (BN_num_bits(bn) & 0x7)
103 pad = 0;
104 else
105 pad = 1;
106 if (cont) {
107 if (pad)
108 *cont++ = 0;
109 BN_bn2bin(bn, cont);
110 }
111 return pad + BN_num_bytes(bn);
112 }
113
bn_c2i(ASN1_VALUE ** pval,const unsigned char * cont,int len,int utype,char * free_cont,const ASN1_ITEM * it)114 static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
115 int utype, char *free_cont, const ASN1_ITEM *it)
116 {
117 BIGNUM *bn;
118
119 if (*pval == NULL && !bn_new(pval, it))
120 return 0;
121 bn = (BIGNUM *)*pval;
122 if (!BN_bin2bn(cont, len, bn)) {
123 bn_free(pval, it);
124 return 0;
125 }
126 return 1;
127 }
128
bn_secure_c2i(ASN1_VALUE ** pval,const unsigned char * cont,int len,int utype,char * free_cont,const ASN1_ITEM * it)129 static int bn_secure_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
130 int utype, char *free_cont, const ASN1_ITEM *it)
131 {
132 int ret;
133 BIGNUM *bn;
134
135 if (*pval == NULL && !bn_secure_new(pval, it))
136 return 0;
137
138 ret = bn_c2i(pval, cont, len, utype, free_cont, it);
139 if (!ret)
140 return 0;
141
142 /* Set constant-time flag for all secure BIGNUMS */
143 bn = (BIGNUM *)*pval;
144 BN_set_flags(bn, BN_FLG_CONSTTIME);
145 return ret;
146 }
147
bn_print(BIO * out,const ASN1_VALUE ** pval,const ASN1_ITEM * it,int indent,const ASN1_PCTX * pctx)148 static int bn_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,
149 int indent, const ASN1_PCTX *pctx)
150 {
151 if (!BN_print(out, *(BIGNUM **)pval))
152 return 0;
153 if (BIO_puts(out, "\n") <= 0)
154 return 0;
155 return 1;
156 }
157