1 /*
2 * Copyright 2000-2020 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
14 #define COPY_SIZE(a, b) (sizeof(a) < sizeof(b) ? sizeof(a) : sizeof(b))
15
16 /*
17 * Custom primitive type for long handling. This converts between an
18 * ASN1_INTEGER and a long directly.
19 */
20
21 static int long_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
22 static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it);
23
24 static int long_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,
25 const ASN1_ITEM *it);
26 static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
27 int utype, char *free_cont, const ASN1_ITEM *it);
28 static int long_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,
29 int indent, const ASN1_PCTX *pctx);
30
31 static ASN1_PRIMITIVE_FUNCS long_pf = {
32 NULL, 0,
33 long_new,
34 long_free,
35 long_free, /* Clear should set to initial value */
36 long_c2i,
37 long_i2c,
38 long_print
39 };
40
ASN1_ITEM_start(LONG)41 ASN1_ITEM_start(LONG)
42 ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &long_pf, ASN1_LONG_UNDEF, "LONG"
43 ASN1_ITEM_end(LONG)
44
45 ASN1_ITEM_start(ZLONG)
46 ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &long_pf, 0, "ZLONG"
47 ASN1_ITEM_end(ZLONG)
48
49 static int long_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
50 {
51 memcpy(pval, &it->size, COPY_SIZE(*pval, it->size));
52 return 1;
53 }
54
long_free(ASN1_VALUE ** pval,const ASN1_ITEM * it)55 static void long_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
56 {
57 memcpy(pval, &it->size, COPY_SIZE(*pval, it->size));
58 }
59
60 /*
61 * Originally BN_num_bits_word was called to perform this operation, but
62 * trouble is that there is no guarantee that sizeof(long) equals to
63 * sizeof(BN_ULONG). BN_ULONG is a configurable type that can be as wide
64 * as long, but also double or half...
65 */
num_bits_ulong(unsigned long value)66 static int num_bits_ulong(unsigned long value)
67 {
68 size_t i;
69 unsigned long ret = 0;
70
71 /*
72 * It is argued that *on average* constant counter loop performs
73 * not worse [if not better] than one with conditional break or
74 * mask-n-table-lookup-style, because of branch misprediction
75 * penalties.
76 */
77 for (i = 0; i < sizeof(value) * 8; i++) {
78 ret += (value != 0);
79 value >>= 1;
80 }
81
82 return (int)ret;
83 }
84
long_i2c(const ASN1_VALUE ** pval,unsigned char * cont,int * putype,const ASN1_ITEM * it)85 static int long_i2c(const ASN1_VALUE **pval, unsigned char *cont, int *putype,
86 const ASN1_ITEM *it)
87 {
88 long ltmp;
89 unsigned long utmp, sign;
90 int clen, pad, i;
91
92 memcpy(<mp, pval, COPY_SIZE(*pval, ltmp));
93 if (ltmp == it->size)
94 return -1;
95 /*
96 * Convert the long to positive: we subtract one if negative so we can
97 * cleanly handle the padding if only the MSB of the leading octet is
98 * set.
99 */
100 if (ltmp < 0) {
101 sign = 0xff;
102 utmp = 0 - (unsigned long)ltmp - 1;
103 } else {
104 sign = 0;
105 utmp = ltmp;
106 }
107 clen = num_bits_ulong(utmp);
108 /* If MSB of leading octet set we need to pad */
109 if (!(clen & 0x7))
110 pad = 1;
111 else
112 pad = 0;
113
114 /* Convert number of bits to number of octets */
115 clen = (clen + 7) >> 3;
116
117 if (cont != NULL) {
118 if (pad)
119 *cont++ = (unsigned char)sign;
120 for (i = clen - 1; i >= 0; i--) {
121 cont[i] = (unsigned char)(utmp ^ sign);
122 utmp >>= 8;
123 }
124 }
125 return clen + pad;
126 }
127
long_c2i(ASN1_VALUE ** pval,const unsigned char * cont,int len,int utype,char * free_cont,const ASN1_ITEM * it)128 static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
129 int utype, char *free_cont, const ASN1_ITEM *it)
130 {
131 int i;
132 long ltmp;
133 unsigned long utmp = 0, sign = 0x100;
134
135 if (len > 1) {
136 /*
137 * Check possible pad byte. Worst case, we're skipping past actual
138 * content, but since that's only with 0x00 and 0xff and we set neg
139 * accordingly, the result will be correct in the end anyway.
140 */
141 switch (cont[0]) {
142 case 0xff:
143 cont++;
144 len--;
145 sign = 0xff;
146 break;
147 case 0:
148 cont++;
149 len--;
150 sign = 0;
151 break;
152 }
153 }
154 if (len > (int)sizeof(long)) {
155 ERR_raise(ERR_LIB_ASN1, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
156 return 0;
157 }
158
159 if (sign == 0x100) {
160 /* Is it negative? */
161 if (len && (cont[0] & 0x80))
162 sign = 0xff;
163 else
164 sign = 0;
165 } else if (((sign ^ cont[0]) & 0x80) == 0) { /* same sign bit? */
166 ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_PADDING);
167 return 0;
168 }
169 utmp = 0;
170 for (i = 0; i < len; i++) {
171 utmp <<= 8;
172 utmp |= cont[i] ^ sign;
173 }
174 ltmp = (long)utmp;
175 if (ltmp < 0) {
176 ERR_raise(ERR_LIB_ASN1, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
177 return 0;
178 }
179 if (sign)
180 ltmp = -ltmp - 1;
181 if (ltmp == it->size) {
182 ERR_raise(ERR_LIB_ASN1, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
183 return 0;
184 }
185 memcpy(pval, <mp, COPY_SIZE(*pval, ltmp));
186 return 1;
187 }
188
long_print(BIO * out,const ASN1_VALUE ** pval,const ASN1_ITEM * it,int indent,const ASN1_PCTX * pctx)189 static int long_print(BIO *out, const ASN1_VALUE **pval, const ASN1_ITEM *it,
190 int indent, const ASN1_PCTX *pctx)
191 {
192 long l;
193
194 memcpy(&l, pval, COPY_SIZE(*pval, l));
195 return BIO_printf(out, "%ld\n", l);
196 }
197