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>
37 #include <stdio.h>
38
39 #include "crc32.h"
40 #include "tcplay.h"
41
42 int
tc_cipher_chain_populate_keys(struct tc_cipher_chain * cipher_chain,unsigned char * key)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 = tc_cipher_chain_klen(cipher_chain);
54
55 /*
56 * Now we need to get prepare the keys, as the keys are in
57 * forward order with respect to the cipher cascade, but
58 * the actual decryption is in reverse cipher cascade order.
59 */
60 used_key_bytes = 0;
61 for (dummy_chain = cipher_chain;
62 dummy_chain != NULL;
63 dummy_chain = dummy_chain->next) {
64 dummy_chain->key = alloc_safe_mem(dummy_chain->cipher->klen);
65 if (dummy_chain->key == NULL) {
66 tc_log(1, "tc_decrypt: Could not allocate key "
67 "memory\n");
68 return ENOMEM;
69 }
70
71 /* XXX: here we assume XTS operation! */
72 memcpy(dummy_chain->key,
73 key + used_key_bytes/2,
74 dummy_chain->cipher->klen/2);
75 memcpy(dummy_chain->key + dummy_chain->cipher->klen/2,
76 key + (total_key_bytes/2) + used_key_bytes/2,
77 dummy_chain->cipher->klen/2);
78
79 /* Remember how many key bytes we've seen */
80 used_key_bytes += dummy_chain->cipher->klen;
81 }
82
83 return 0;
84 }
85
86 int
tc_cipher_chain_free_keys(struct tc_cipher_chain * cipher_chain)87 tc_cipher_chain_free_keys(struct tc_cipher_chain *cipher_chain)
88 {
89 for (; cipher_chain != NULL; cipher_chain = cipher_chain->next) {
90 if (cipher_chain->key != NULL) {
91 free_safe_mem(cipher_chain->key);
92 cipher_chain->key = NULL;
93 }
94 }
95
96 return 0;
97 }
98
99 int
tc_encrypt(struct tc_cipher_chain * cipher_chain,unsigned char * key,unsigned char * iv,unsigned char * in,int in_len,unsigned char * out)100 tc_encrypt(struct tc_cipher_chain *cipher_chain, unsigned char *key,
101 unsigned char *iv,
102 unsigned char *in, int in_len, unsigned char *out)
103 {
104 struct tc_cipher_chain *chain_start;
105 int err;
106
107 chain_start = cipher_chain;
108
109 if ((err = tc_cipher_chain_populate_keys(cipher_chain, key)))
110 return err;
111
112 #ifdef DEBUG
113 printf("tc_encrypt: starting chain\n");
114 #endif
115
116 /*
117 * Now process the actual decryption, in forward cascade order.
118 */
119 for (;
120 cipher_chain != NULL;
121 cipher_chain = cipher_chain->next) {
122 #ifdef DEBUG
123 printf("tc_encrypt: Currently using cipher %s\n",
124 cipher_chain->cipher->name);
125 #endif
126
127 err = syscrypt(cipher_chain->cipher, cipher_chain->key,
128 cipher_chain->cipher->klen, iv, in, out, in_len, 1);
129
130 /* Deallocate this key, since we won't need it anymore */
131 free_safe_mem(cipher_chain->key);
132 cipher_chain->key = NULL;
133
134 if (err != 0) {
135 tc_cipher_chain_free_keys(chain_start);
136 return err;
137 }
138
139 /* Set next input buffer as current output buffer */
140 in = out;
141 }
142
143 tc_cipher_chain_free_keys(chain_start);
144
145 return 0;
146 }
147
148 int
tc_decrypt(struct tc_cipher_chain * cipher_chain,unsigned char * key,unsigned char * iv,unsigned char * in,int in_len,unsigned char * out)149 tc_decrypt(struct tc_cipher_chain *cipher_chain, unsigned char *key,
150 unsigned char *iv,
151 unsigned char *in, int in_len, unsigned char *out)
152 {
153 struct tc_cipher_chain *chain_start;
154 int err;
155
156 chain_start = cipher_chain;
157
158 if ((err = tc_cipher_chain_populate_keys(cipher_chain, key)))
159 return err;
160
161 #ifdef DEBUG
162 printf("tc_decrypt: starting chain!\n");
163 #endif
164
165 /*
166 * Now process the actual decryption, in reverse cascade order; so
167 * first find the last element in the chain.
168 */
169 for (; cipher_chain->next != NULL; cipher_chain = cipher_chain->next)
170 ;
171 for (;
172 cipher_chain != NULL;
173 cipher_chain = cipher_chain->prev) {
174 #ifdef DEBUG
175 printf("tc_decrypt: Currently using cipher %s\n",
176 cipher_chain->cipher->name);
177 #endif
178
179 err = syscrypt(cipher_chain->cipher, cipher_chain->key,
180 cipher_chain->cipher->klen, iv, in, out, in_len, 0);
181
182 /* Deallocate this key, since we won't need it anymore */
183 free_safe_mem(cipher_chain->key);
184 cipher_chain->key = NULL;
185
186 if (err != 0) {
187 tc_cipher_chain_free_keys(chain_start);
188 return err;
189 }
190
191 /* Set next input buffer as current output buffer */
192 in = out;
193 }
194
195 tc_cipher_chain_free_keys(chain_start);
196
197 return 0;
198 }
199
200 int
apply_keyfiles(unsigned char * pass,size_t pass_memsz,const char * keyfiles[],int nkeyfiles)201 apply_keyfiles(unsigned char *pass, size_t pass_memsz, const char *keyfiles[],
202 int nkeyfiles)
203 {
204 int pl, k;
205 unsigned char *kpool;
206 unsigned char *kdata;
207 int kpool_idx;
208 size_t i, kdata_sz;
209 uint32_t crc;
210
211 if (pass_memsz < MAX_PASSSZ) {
212 tc_log(1, "Not enough memory for password manipulation\n");
213 return ENOMEM;
214 }
215
216 pl = strlen((char *)pass);
217 memset(pass+pl, 0, MAX_PASSSZ-pl);
218
219 if ((kpool = alloc_safe_mem(KPOOL_SZ)) == NULL) {
220 tc_log(1, "Error allocating memory for keyfile pool\n");
221 return ENOMEM;
222 }
223
224 memset(kpool, 0, KPOOL_SZ);
225
226 for (k = 0; k < nkeyfiles; k++) {
227 #ifdef DEBUG
228 printf("Loading keyfile %s into kpool\n", keyfiles[k]);
229 #endif
230 kpool_idx = 0;
231 crc = ~0U;
232 kdata_sz = MAX_KFILE_SZ;
233
234 if ((kdata = read_to_safe_mem(keyfiles[k], 0, &kdata_sz)) == NULL) {
235 tc_log(1, "Error reading keyfile %s content\n",
236 keyfiles[k]);
237 free_safe_mem(kpool);
238 return EIO;
239 }
240
241 for (i = 0; i < kdata_sz; i++) {
242 crc = crc32_intermediate(crc, kdata[i]);
243
244 kpool[kpool_idx++] += (unsigned char)(crc >> 24);
245 kpool[kpool_idx++] += (unsigned char)(crc >> 16);
246 kpool[kpool_idx++] += (unsigned char)(crc >> 8);
247 kpool[kpool_idx++] += (unsigned char)(crc);
248
249 /* Wrap around */
250 if (kpool_idx == KPOOL_SZ)
251 kpool_idx = 0;
252 }
253
254 free_safe_mem(kdata);
255 }
256
257 #ifdef DEBUG
258 printf("Applying kpool to passphrase\n");
259 #endif
260 /* Apply keyfile pool to passphrase */
261 for (i = 0; i < KPOOL_SZ; i++)
262 pass[i] += kpool[i];
263
264 free_safe_mem(kpool);
265
266 return 0;
267 }
268