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65808bd3 »
2011-07-20 separate out bits; implement gcrypt backend
1 /*
2 * Copyright (c) 2011 Alex Hornung <alex@alexhornung.com>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
14 * distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
19 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
20 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
22 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
24 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29 #include <sys/types.h>
30 #include <sys/param.h>
31 #include <inttypes.h>
32
33 #include <fcntl.h>
34 #include <unistd.h>
35 #include <errno.h>
36 #include <string.h>
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37 #include <stdio.h>
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38
39 #include "crc32.h"
40 #include "tcplay.h"
41
42 int
43 tc_cipher_chain_populate_keys(struct tc_cipher_chain *cipher_chain,
44 unsigned char *key)
45 {
46 int total_key_bytes, used_key_bytes;
47 struct tc_cipher_chain *dummy_chain;
48
49 /*
50 * We need to determine the total key bytes as the key locations
51 * depend on it.
52 */
53 total_key_bytes = 0;
54 for (dummy_chain = cipher_chain;
55 dummy_chain != NULL;
56 dummy_chain = dummy_chain->next) {
57 total_key_bytes += dummy_chain->cipher->klen;
58 }
59
60 /*
61 * Now we need to get prepare the keys, as the keys are in
62 * forward order with respect to the cipher cascade, but
63 * the actual decryption is in reverse cipher cascade order.
64 */
65 used_key_bytes = 0;
66 for (dummy_chain = cipher_chain;
67 dummy_chain != NULL;
68 dummy_chain = dummy_chain->next) {
69 dummy_chain->key = alloc_safe_mem(dummy_chain->cipher->klen);
70 if (dummy_chain->key == NULL) {
71 tc_log(1, "tc_decrypt: Could not allocate key "
72 "memory\n");
73 return ENOMEM;
74 }
75
76 /* XXX: here we assume XTS operation! */
77 memcpy(dummy_chain->key,
78 key + used_key_bytes/2,
79 dummy_chain->cipher->klen/2);
80 memcpy(dummy_chain->key + dummy_chain->cipher->klen/2,
81 key + (total_key_bytes/2) + used_key_bytes/2,
82 dummy_chain->cipher->klen/2);
83
84 /* Remember how many key bytes we've seen */
85 used_key_bytes += dummy_chain->cipher->klen;
86 }
87
88 return 0;
89 }
90
91 int
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92 tc_cipher_chain_free_keys(struct tc_cipher_chain *cipher_chain)
93 {
94 for (; cipher_chain != NULL; cipher_chain = cipher_chain->next) {
95 if (cipher_chain->key != NULL) {
96 free_safe_mem(cipher_chain->key);
97 cipher_chain->key = NULL;
98 }
99 }
100
101 return 0;
102 }
103
104 int
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2011-07-20 separate out bits; implement gcrypt backend
105 tc_encrypt(struct tc_cipher_chain *cipher_chain, unsigned char *key,
106 unsigned char *iv,
107 unsigned char *in, int in_len, unsigned char *out)
108 {
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109 struct tc_cipher_chain *chain_start;
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2011-07-20 separate out bits; implement gcrypt backend
110 int err;
111
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112 chain_start = cipher_chain;
113
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2011-07-20 separate out bits; implement gcrypt backend
114 if ((err = tc_cipher_chain_populate_keys(cipher_chain, key)))
115 return err;
116
117 #ifdef DEBUG
118 printf("tc_encrypt: starting chain\n");
119 #endif
120
121 /*
122 * Now process the actual decryption, in forward cascade order.
123 */
124 for (;
125 cipher_chain != NULL;
126 cipher_chain = cipher_chain->next) {
127 #ifdef DEBUG
128 printf("tc_encrypt: Currently using cipher %s\n",
129 cipher_chain->cipher->name);
130 #endif
131
132 err = syscrypt(cipher_chain->cipher, cipher_chain->key,
133 cipher_chain->cipher->klen, iv, in, out, in_len, 1);
134
135 /* Deallocate this key, since we won't need it anymore */
136 free_safe_mem(cipher_chain->key);
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137 cipher_chain->key = NULL;
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138
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139 if (err != 0) {
140 tc_cipher_chain_free_keys(chain_start);
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141 return err;
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142 }
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143
144 /* Set next input buffer as current output buffer */
145 in = out;
146 }
147
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148 tc_cipher_chain_free_keys(chain_start);
149
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2011-07-20 separate out bits; implement gcrypt backend
150 return 0;
151 }
152
153 int
154 tc_decrypt(struct tc_cipher_chain *cipher_chain, unsigned char *key,
155 unsigned char *iv,
156 unsigned char *in, int in_len, unsigned char *out)
157 {
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158 struct tc_cipher_chain *chain_start;
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159 int err;
160
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161 chain_start = cipher_chain;
162
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2011-07-20 separate out bits; implement gcrypt backend
163 if ((err = tc_cipher_chain_populate_keys(cipher_chain, key)))
164 return err;
165
166 #ifdef DEBUG
167 printf("tc_decrypt: starting chain!\n");
168 #endif
169
170 /*
171 * Now process the actual decryption, in reverse cascade order; so
172 * first find the last element in the chain.
173 */
174 for (; cipher_chain->next != NULL; cipher_chain = cipher_chain->next)
175 ;
176 for (;
177 cipher_chain != NULL;
178 cipher_chain = cipher_chain->prev) {
179 #ifdef DEBUG
180 printf("tc_decrypt: Currently using cipher %s\n",
181 cipher_chain->cipher->name);
182 #endif
183
184 err = syscrypt(cipher_chain->cipher, cipher_chain->key,
185 cipher_chain->cipher->klen, iv, in, out, in_len, 0);
186
187 /* Deallocate this key, since we won't need it anymore */
188 free_safe_mem(cipher_chain->key);
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189 cipher_chain->key = NULL;
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190
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191 if (err != 0) {
192 tc_cipher_chain_free_keys(chain_start);
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193 return err;
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194 }
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195
196 /* Set next input buffer as current output buffer */
197 in = out;
198 }
199
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200 tc_cipher_chain_free_keys(chain_start);
201
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2011-07-20 separate out bits; implement gcrypt backend
202 return 0;
203 }
204
205 int
206 apply_keyfiles(unsigned char *pass, size_t pass_memsz, const char *keyfiles[],
207 int nkeyfiles)
208 {
209 int pl, k;
210 unsigned char *kpool;
211 unsigned char *kdata;
212 int kpool_idx;
213 size_t i, kdata_sz;
214 uint32_t crc;
215
216 if (pass_memsz < MAX_PASSSZ) {
217 tc_log(1, "Not enough memory for password manipluation\n");
218 return ENOMEM;
219 }
220
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221 pl = strlen((char *)pass);
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2011-07-20 separate out bits; implement gcrypt backend
222 memset(pass+pl, 0, MAX_PASSSZ-pl);
223
224 if ((kpool = alloc_safe_mem(KPOOL_SZ)) == NULL) {
225 tc_log(1, "Error allocating memory for keyfile pool\n");
226 return ENOMEM;
227 }
228
229 memset(kpool, 0, KPOOL_SZ);
230
231 for (k = 0; k < nkeyfiles; k++) {
232 #ifdef DEBUG
233 printf("Loading keyfile %s into kpool\n", keyfiles[k]);
234 #endif
235 kpool_idx = 0;
236 crc = ~0U;
237 kdata_sz = MAX_KFILE_SZ;
238
239 if ((kdata = read_to_safe_mem(keyfiles[k], 0, &kdata_sz)) == NULL) {
240 tc_log(1, "Error reading keyfile %s content\n",
241 keyfiles[k]);
242 free_safe_mem(kpool);
243 return EIO;
244 }
245
246 for (i = 0; i < kdata_sz; i++) {
247 crc = crc32_intermediate(crc, kdata[i]);
248
249 kpool[kpool_idx++] += (unsigned char)(crc >> 24);
250 kpool[kpool_idx++] += (unsigned char)(crc >> 16);
251 kpool[kpool_idx++] += (unsigned char)(crc >> 8);
252 kpool[kpool_idx++] += (unsigned char)(crc);
253
254 /* Wrap around */
255 if (kpool_idx == KPOOL_SZ)
256 kpool_idx = 0;
257 }
258
259 free_safe_mem(kdata);
260 }
261
262 #ifdef DEBUG
263 printf("Applying kpool to passphrase\n");
264 #endif
265 /* Apply keyfile pool to passphrase */
266 for (i = 0; i < KPOOL_SZ; i++)
267 pass[i] += kpool[i];
268
269 free_safe_mem(kpool);
270
271 return 0;
272 }
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