1 /* $OpenBSD: bufbn.c,v 1.6 2007/06/02 09:04:58 djm Exp $*/
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Auxiliary functions for storing and retrieving various data types to/from
7 * Buffers.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 *
15 *
16 * SSH2 packet format added by Markus Friedl
17 * Copyright (c) 2000 Markus Friedl. All rights reserved.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 */
39
40 #include <sys/types.h>
41 #include <sys/time.h>
42
43 #include <openssl/bn.h>
44
45 #include <string.h>
46 #include <stdarg.h>
47
48 #include "xmalloc.h"
49 #include "buffer.h"
50 #include "log.h"
51 #include "misc.h"
52
53 __RCSID("$MirOS: src/usr.bin/ssh/bufbn.c,v 1.2 2008/12/16 22:13:27 tg Exp $");
54
55 /*
56 * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
57 * by (bits+7)/8 bytes of binary data, msb first.
58 */
59 int
buffer_put_bignum_ret(Buffer * buffer,const BIGNUM * value)60 buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value)
61 {
62 int bits = BN_num_bits(value);
63 int bin_size = (bits + 7) / 8;
64 u_char *buf = xmalloc(bin_size);
65 int oi;
66 char msg[2];
67
68 /* Get the value of in binary */
69 oi = BN_bn2bin(value, buf);
70 if (oi != bin_size) {
71 error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d",
72 oi, bin_size);
73 xfree(buf);
74 return (-1);
75 }
76
77 /* Store the number of bits in the buffer in two bytes, msb first. */
78 put_u16(msg, bits);
79 buffer_append(buffer, msg, 2);
80 /* Store the binary data. */
81 buffer_append(buffer, buf, oi);
82
83 memset(buf, 0, bin_size);
84 xfree(buf);
85
86 return (0);
87 }
88
89 void
buffer_put_bignum(Buffer * buffer,const BIGNUM * value)90 buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
91 {
92 if (buffer_put_bignum_ret(buffer, value) == -1)
93 fatal("buffer_put_bignum: buffer error");
94 }
95
96 /*
97 * Retrieves a BIGNUM from the buffer.
98 */
99 int
buffer_get_bignum_ret(Buffer * buffer,BIGNUM * value)100 buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value)
101 {
102 u_int bits, bytes;
103 u_char buf[2], *bin;
104
105 /* Get the number of bits. */
106 if (buffer_get_ret(buffer, (char *) buf, 2) == -1) {
107 error("buffer_get_bignum_ret: invalid length");
108 return (-1);
109 }
110 bits = get_u16(buf);
111 /* Compute the number of binary bytes that follow. */
112 bytes = (bits + 7) / 8;
113 if (bytes > 8 * 1024) {
114 error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
115 return (-1);
116 }
117 if (buffer_len(buffer) < bytes) {
118 error("buffer_get_bignum_ret: input buffer too small");
119 return (-1);
120 }
121 bin = buffer_ptr(buffer);
122 if (BN_bin2bn(bin, bytes, value) == NULL) {
123 error("buffer_get_bignum_ret: BN_bin2bn failed");
124 return (-1);
125 }
126 if (buffer_consume_ret(buffer, bytes) == -1) {
127 error("buffer_get_bignum_ret: buffer_consume failed");
128 return (-1);
129 }
130 return (0);
131 }
132
133 void
buffer_get_bignum(Buffer * buffer,BIGNUM * value)134 buffer_get_bignum(Buffer *buffer, BIGNUM *value)
135 {
136 if (buffer_get_bignum_ret(buffer, value) == -1)
137 fatal("buffer_get_bignum: buffer error");
138 }
139
140 /*
141 * Stores a BIGNUM in the buffer in SSH2 format.
142 */
143 int
buffer_put_bignum2_ret(Buffer * buffer,const BIGNUM * value)144 buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
145 {
146 u_int bytes;
147 u_char *buf;
148 int oi;
149 u_int hasnohigh = 0;
150
151 if (BN_is_zero(value)) {
152 buffer_put_int(buffer, 0);
153 return 0;
154 }
155 if (value->neg) {
156 error("buffer_put_bignum2_ret: negative numbers not supported");
157 return (-1);
158 }
159 bytes = BN_num_bytes(value) + 1; /* extra padding byte */
160 if (bytes < 2) {
161 error("buffer_put_bignum2_ret: BN too small");
162 return (-1);
163 }
164 buf = xmalloc(bytes);
165 buf[0] = 0x00;
166 /* Get the value of in binary */
167 oi = BN_bn2bin(value, buf+1);
168 if (oi < 0 || (u_int)oi != bytes - 1) {
169 error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
170 "oi %d != bin_size %d", oi, bytes);
171 xfree(buf);
172 return (-1);
173 }
174 hasnohigh = (buf[1] & 0x80) ? 0 : 1;
175 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
176 memset(buf, 0, bytes);
177 xfree(buf);
178 return (0);
179 }
180
181 void
buffer_put_bignum2(Buffer * buffer,const BIGNUM * value)182 buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
183 {
184 if (buffer_put_bignum2_ret(buffer, value) == -1)
185 fatal("buffer_put_bignum2: buffer error");
186 }
187
188 int
buffer_get_bignum2_ret(Buffer * buffer,BIGNUM * value)189 buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
190 {
191 u_int len;
192 u_char *bin;
193
194 if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
195 error("buffer_get_bignum2_ret: invalid bignum");
196 return (-1);
197 }
198
199 if (len > 0 && (bin[0] & 0x80)) {
200 error("buffer_get_bignum2_ret: negative numbers not supported");
201 xfree(bin);
202 return (-1);
203 }
204 if (len > 8 * 1024) {
205 error("buffer_get_bignum2_ret: cannot handle BN of size %d",
206 len);
207 xfree(bin);
208 return (-1);
209 }
210 if (BN_bin2bn(bin, len, value) == NULL) {
211 error("buffer_get_bignum2_ret: BN_bin2bn failed");
212 xfree(bin);
213 return (-1);
214 }
215 xfree(bin);
216 return (0);
217 }
218
219 void
buffer_get_bignum2(Buffer * buffer,BIGNUM * value)220 buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
221 {
222 if (buffer_get_bignum2_ret(buffer, value) == -1)
223 fatal("buffer_get_bignum2: buffer error");
224 }
225