1 /* $OpenBSD: bufbn.c,v 1.6 2007/06/02 09:04:58 djm Exp $*/ 2 /* 3 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo (at) 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 49 #include "xmalloc.h" 50 #include "buffer.h" 51 #include "log.h" 52 #include "misc.h" 53 54 /* 55 * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed 56 * by (bits+7)/8 bytes of binary data, msb first. 57 */ 58 int 59 buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value) 60 { 61 int bits = BN_num_bits(value); 62 int bin_size = (bits + 7) / 8; 63 u_char *buf = xmalloc(bin_size); 64 int oi; 65 char msg[2]; 66 67 /* Get the value of in binary */ 68 oi = BN_bn2bin(value, buf); 69 if (oi != bin_size) { 70 error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d", 71 oi, bin_size); 72 xfree(buf); 73 return (-1); 74 } 75 76 /* Store the number of bits in the buffer in two bytes, msb first. */ 77 put_u16(msg, bits); 78 buffer_append(buffer, msg, 2); 79 /* Store the binary data. */ 80 buffer_append(buffer, buf, oi); 81 82 memset(buf, 0, bin_size); 83 xfree(buf); 84 85 return (0); 86 } 87 88 void 89 buffer_put_bignum(Buffer *buffer, const BIGNUM *value) 90 { 91 if (buffer_put_bignum_ret(buffer, value) == -1) 92 fatal("buffer_put_bignum: buffer error"); 93 } 94 95 /* 96 * Retrieves a BIGNUM from the buffer. 97 */ 98 int 99 buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value) 100 { 101 u_int bits, bytes; 102 u_char buf[2], *bin; 103 104 /* Get the number of bits. */ 105 if (buffer_get_ret(buffer, (char *) buf, 2) == -1) { 106 error("buffer_get_bignum_ret: invalid length"); 107 return (-1); 108 } 109 bits = get_u16(buf); 110 /* Compute the number of binary bytes that follow. */ 111 bytes = (bits + 7) / 8; 112 if (bytes > 8 * 1024) { 113 error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes); 114 return (-1); 115 } 116 if (buffer_len(buffer) < bytes) { 117 error("buffer_get_bignum_ret: input buffer too small"); 118 return (-1); 119 } 120 bin = buffer_ptr(buffer); 121 if (BN_bin2bn(bin, bytes, value) == NULL) { 122 error("buffer_get_bignum_ret: BN_bin2bn failed"); 123 return (-1); 124 } 125 if (buffer_consume_ret(buffer, bytes) == -1) { 126 error("buffer_get_bignum_ret: buffer_consume failed"); 127 return (-1); 128 } 129 return (0); 130 } 131 132 void 133 buffer_get_bignum(Buffer *buffer, BIGNUM *value) 134 { 135 if (buffer_get_bignum_ret(buffer, value) == -1) 136 fatal("buffer_get_bignum: buffer error"); 137 } 138 139 /* 140 * Stores a BIGNUM in the buffer in SSH2 format. 141 */ 142 int 143 buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value) 144 { 145 u_int bytes; 146 u_char *buf; 147 int oi; 148 u_int hasnohigh = 0; 149 150 if (BN_is_zero(value)) { 151 buffer_put_int(buffer, 0); 152 return 0; 153 } 154 if (value->neg) { 155 error("buffer_put_bignum2_ret: negative numbers not supported"); 156 return (-1); 157 } 158 bytes = BN_num_bytes(value) + 1; /* extra padding byte */ 159 if (bytes < 2) { 160 error("buffer_put_bignum2_ret: BN too small"); 161 return (-1); 162 } 163 buf = xmalloc(bytes); 164 buf[0] = 0x00; 165 /* Get the value of in binary */ 166 oi = BN_bn2bin(value, buf+1); 167 if (oi < 0 || (u_int)oi != bytes - 1) { 168 error("buffer_put_bignum2_ret: BN_bn2bin() failed: " 169 "oi %d != bin_size %d", oi, bytes); 170 xfree(buf); 171 return (-1); 172 } 173 hasnohigh = (buf[1] & 0x80) ? 0 : 1; 174 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh); 175 memset(buf, 0, bytes); 176 xfree(buf); 177 return (0); 178 } 179 180 void 181 buffer_put_bignum2(Buffer *buffer, const BIGNUM *value) 182 { 183 if (buffer_put_bignum2_ret(buffer, value) == -1) 184 fatal("buffer_put_bignum2: buffer error"); 185 } 186 187 int 188 buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value) 189 { 190 u_int len; 191 u_char *bin; 192 193 if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) { 194 error("buffer_get_bignum2_ret: invalid bignum"); 195 return (-1); 196 } 197 198 if (len > 0 && (bin[0] & 0x80)) { 199 error("buffer_get_bignum2_ret: negative numbers not supported"); 200 xfree(bin); 201 return (-1); 202 } 203 if (len > 8 * 1024) { 204 error("buffer_get_bignum2_ret: cannot handle BN of size %d", 205 len); 206 xfree(bin); 207 return (-1); 208 } 209 if (BN_bin2bn(bin, len, value) == NULL) { 210 error("buffer_get_bignum2_ret: BN_bin2bn failed"); 211 xfree(bin); 212 return (-1); 213 } 214 xfree(bin); 215 return (0); 216 } 217 218 void 219 buffer_get_bignum2(Buffer *buffer, BIGNUM *value) 220 { 221 if (buffer_get_bignum2_ret(buffer, value) == -1) 222 fatal("buffer_get_bignum2: buffer error"); 223 } 224
