1 /* $OpenBSD: bufbn.c,v 1.11 2014/02/27 08:25:09 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 "includes.h"
41
42 #include <sys/types.h>
43
44 #include <openssl/bn.h>
45
46 #include <string.h>
47 #include <stdarg.h>
48 #include <stdlib.h>
49
50 #include "xmalloc.h"
51 #include "buffer.h"
52 #include "log.h"
53 #include "misc.h"
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 free(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 explicit_bzero(buf, bin_size);
84 free(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 if (bits > 65535-7) {
112 error("buffer_get_bignum_ret: cannot handle BN of size %d",
113 bits);
114 return (-1);
115 }
116 /* Compute the number of binary bytes that follow. */
117 bytes = (bits + 7) / 8;
118 if (bytes > 8 * 1024) {
119 error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
120 return (-1);
121 }
122 if (buffer_len(buffer) < bytes) {
123 error("buffer_get_bignum_ret: input buffer too small");
124 return (-1);
125 }
126 bin = buffer_ptr(buffer);
127 if (BN_bin2bn(bin, bytes, value) == NULL) {
128 error("buffer_get_bignum_ret: BN_bin2bn failed");
129 return (-1);
130 }
131 if (buffer_consume_ret(buffer, bytes) == -1) {
132 error("buffer_get_bignum_ret: buffer_consume failed");
133 return (-1);
134 }
135 return (0);
136 }
137
138 void
buffer_get_bignum(Buffer * buffer,BIGNUM * value)139 buffer_get_bignum(Buffer *buffer, BIGNUM *value)
140 {
141 if (buffer_get_bignum_ret(buffer, value) == -1)
142 fatal("buffer_get_bignum: buffer error");
143 }
144
145 /*
146 * Stores a BIGNUM in the buffer in SSH2 format.
147 */
148 int
buffer_put_bignum2_ret(Buffer * buffer,const BIGNUM * value)149 buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
150 {
151 u_int bytes;
152 u_char *buf;
153 int oi;
154 u_int hasnohigh = 0;
155
156 if (BN_is_zero(value)) {
157 buffer_put_int(buffer, 0);
158 return 0;
159 }
160 if (value->neg) {
161 error("buffer_put_bignum2_ret: negative numbers not supported");
162 return (-1);
163 }
164 bytes = BN_num_bytes(value) + 1; /* extra padding byte */
165 if (bytes < 2) {
166 error("buffer_put_bignum2_ret: BN too small");
167 return (-1);
168 }
169 buf = xmalloc(bytes);
170 buf[0] = 0x00;
171 /* Get the value of in binary */
172 oi = BN_bn2bin(value, buf+1);
173 if (oi < 0 || (u_int)oi != bytes - 1) {
174 error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
175 "oi %d != bin_size %d", oi, bytes);
176 free(buf);
177 return (-1);
178 }
179 hasnohigh = (buf[1] & 0x80) ? 0 : 1;
180 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
181 explicit_bzero(buf, bytes);
182 free(buf);
183 return (0);
184 }
185
186 void
buffer_put_bignum2(Buffer * buffer,const BIGNUM * value)187 buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
188 {
189 if (buffer_put_bignum2_ret(buffer, value) == -1)
190 fatal("buffer_put_bignum2: buffer error");
191 }
192
193 int
buffer_get_bignum2_ret(Buffer * buffer,BIGNUM * value)194 buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
195 {
196 u_int len;
197 u_char *bin;
198
199 if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
200 error("buffer_get_bignum2_ret: invalid bignum");
201 return (-1);
202 }
203
204 if (len > 0 && (bin[0] & 0x80)) {
205 error("buffer_get_bignum2_ret: negative numbers not supported");
206 free(bin);
207 return (-1);
208 }
209 if (len > 8 * 1024) {
210 error("buffer_get_bignum2_ret: cannot handle BN of size %d",
211 len);
212 free(bin);
213 return (-1);
214 }
215 if (BN_bin2bn(bin, len, value) == NULL) {
216 error("buffer_get_bignum2_ret: BN_bin2bn failed");
217 free(bin);
218 return (-1);
219 }
220 free(bin);
221 return (0);
222 }
223
224 void
buffer_get_bignum2(Buffer * buffer,BIGNUM * value)225 buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
226 {
227 if (buffer_get_bignum2_ret(buffer, value) == -1)
228 fatal("buffer_get_bignum2: buffer error");
229 }
230