1/*
2 * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 as published
6 * by the Free Software Foundation.
7 *
8 */
9
10#include <stdio.h>
11#include <stdlib.h>
12#include <string.h>
13#include <errno.h>
14#include <unistd.h>
15#include <sys/stat.h>
16
17#include "buffalo-lib.h"
18
19static uint32_t crc32_table[256] =
20{
21	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
22	0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
23	0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
24	0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
25	0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
26	0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
27	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
28	0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
29	0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
30	0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
31	0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
32	0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
33	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
34	0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
35	0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
36	0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
37	0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
38	0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
39	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
40	0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
41	0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
42	0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
43	0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
44	0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
45	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
46	0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
47	0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
48	0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
49	0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
50	0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
51	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
52	0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
53	0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
54	0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
55	0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
56	0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
57	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
58	0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
59	0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
60	0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
61	0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
62	0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
63	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
64	0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
65	0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
66	0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
67	0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
68	0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
69	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
70	0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
71	0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
72	0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
73	0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
74	0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
75	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
76	0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
77	0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
78	0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
79	0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
80	0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
81	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
82	0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
83	0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
84	0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
85};
86
87int bcrypt_init(struct bcrypt_ctx *ctx, void *key, int keylen,
88		unsigned long state_len)
89{
90	unsigned char *state;
91	unsigned char *p = key;
92	unsigned long i, j;
93	unsigned long k = 0;
94
95	state = malloc(state_len);
96	if (state == NULL)
97		return -1;
98
99	ctx->i = 0;
100	ctx->j = 0;
101	ctx->state = state;
102	ctx->state_len = state_len;
103
104	for (i = 0; i < state_len; i++)
105		state[i] = i;
106
107	for(i = 0, j = 0; i < state_len; i++, j = (j + 1) % keylen) {
108		unsigned char t;
109
110		t = state[i];
111		k = (k + p[j] + t) % state_len;
112		state[i] = state[k];
113		state[k] = t;
114	}
115
116	return 0;
117}
118
119int bcrypt_process(struct bcrypt_ctx *ctx, unsigned char *src,
120		   unsigned char *dst, unsigned long len)
121{
122	unsigned char *state = ctx->state;
123	unsigned long state_len = ctx->state_len;
124	unsigned char i, j;
125	unsigned long k;
126
127	i = ctx->i;
128	j = ctx->j;
129
130	for (k = 0; k < len; k++) {
131		unsigned char t;
132
133		i = (i + 1) % state_len;
134		j = (j + state[i]) % state_len;
135		t = state[j];
136		state[j] = state[i];
137		state[i] = t;
138
139		dst[k] = src[k] ^ state[(state[i] + state[j]) % state_len];
140	}
141
142	ctx->i = i;
143	ctx->j = j;
144
145	return len;
146}
147
148void bcrypt_finish(struct bcrypt_ctx *ctx)
149{
150	if (ctx->state)
151		free(ctx->state);
152}
153
154int bcrypt_buf(unsigned char seed, unsigned char *key, unsigned char *src,
155	       unsigned char *dst, unsigned long len, int longstate)
156{
157	unsigned char bckey[BCRYPT_MAX_KEYLEN + 1];
158	unsigned int keylen;
159	struct bcrypt_ctx ctx;
160	int ret;
161
162	/* setup decryption key */
163	keylen = strlen((char *) key);
164	bckey[0] = seed;
165	memcpy(&bckey[1], key, keylen);
166
167	keylen++;
168
169	ret = bcrypt_init(&ctx, bckey, keylen,
170			  (longstate) ? len : BCRYPT_DEFAULT_STATE_LEN);
171	if (ret)
172		return ret;
173
174	bcrypt_process(&ctx, src, dst, len);
175	bcrypt_finish(&ctx);
176
177	return 0;
178}
179
180uint32_t buffalo_csum(uint32_t csum, void *buf, unsigned long len)
181{
182	char *p = buf;
183
184	while (len--) {
185		int i;
186
187		csum ^= *p++;
188		for (i = 0; i < 8; i++)
189			csum = (csum >> 1) ^ ((csum & 1) ? 0xedb88320ul : 0);
190	}
191
192	return csum;
193}
194
195uint32_t buffalo_crc(void *buf, unsigned long len)
196{
197	unsigned char *p = buf;
198	unsigned long t = len;
199	uint32_t crc = 0;
200
201	while (len--)
202		crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ *p++) & 0xFF];
203
204	while (t) {
205		crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ t) & 0xFF];
206		t >>= 8;
207	}
208
209	return ~crc;
210}
211
212unsigned long enc_compute_header_len(char *product, char *version)
213{
214	return ENC_MAGIC_LEN + 1 + strlen(product) + 1 +
215	       strlen(version) + 1 + 3 * sizeof(uint32_t);
216}
217
218unsigned long enc_compute_buf_len(char *product, char *version,
219				  unsigned long datalen)
220{
221	unsigned long ret;
222
223	ret = enc_compute_header_len(product, version);
224	ret += datalen + sizeof(uint32_t);
225	ret += (4 - ret % 4);
226
227	return ret;
228}
229
230static void put_be32(void *data, uint32_t val)
231{
232	unsigned char *p = data;
233
234	p[0] = (val >> 24) & 0xff;
235	p[1] = (val >> 16) & 0xff;
236	p[2] = (val >> 8) & 0xff;
237	p[3] = val & 0xff;
238}
239
240static uint32_t get_be32(void *data)
241{
242	unsigned char *p = data;
243
244	return (((uint32_t)p[0]) << 24) |
245	       (((uint32_t)p[1]) << 16) |
246	       (((uint32_t)p[2]) << 8) |
247	       ((uint32_t)p[3]);
248}
249
250static int check_magic(void *magic)
251{
252	if (!memcmp("start", magic, ENC_MAGIC_LEN));
253		return 0;
254
255	if (!memcmp("asar1", magic, ENC_MAGIC_LEN));
256		return 0;
257
258	return -1;
259}
260
261int encrypt_buf(struct enc_param *ep, unsigned char *hdr,
262		unsigned char *data)
263{
264	unsigned char *p;
265	uint32_t len;
266	int err;
267	int ret = -1;
268	unsigned char s;
269
270	p = (unsigned char *) hdr;
271
272	/* setup magic */
273	len = strlen((char *) ep->magic) + 1;
274	memcpy(p, ep->magic, len);
275	p += len;
276
277	/* setup seed */
278	*p++ = ep->seed;
279
280	/* put product len */
281	len = strlen((char *) ep->product) + 1;
282	put_be32(p, len);
283	p += sizeof(uint32_t);
284
285	/* copy and crypt product name */
286	memcpy(p, ep->product, len);
287	err = bcrypt_buf(ep->seed, ep->key, p, p, len, ep->longstate);
288	if (err)
289		goto out;
290	s = *p;
291	p += len;
292
293	/* put version length */
294	len = strlen((char *) ep->version) + 1;
295	put_be32(p, len);
296	p += sizeof(uint32_t);
297
298	/* copy and crypt version */
299	memcpy(p, ep->version, len);
300	err = bcrypt_buf(s, ep->key, p, p, len, ep->longstate);
301	if (err)
302		goto out;
303	s = *p;
304	p += len;
305
306	/* put data length */
307	put_be32(p, ep->datalen);
308
309	/* encrypt data */
310	err = bcrypt_buf(s, ep->key, data, data, ep->datalen, ep->longstate);
311	if (err)
312		goto out;
313
314	/* put checksum */
315	put_be32(&data[ep->datalen], ep->csum);
316
317	ret = 0;
318
319out:
320	return ret;
321}
322
323int decrypt_buf(struct enc_param *ep, unsigned char *data,
324		unsigned long datalen)
325{
326	unsigned char *p;
327	uint32_t prod_len;
328	uint32_t ver_len;
329	uint32_t len;
330	uint32_t csum;
331	ssize_t remain;
332	int err;
333	int ret = -1;
334
335#define CHECKLEN(_l) do {		\
336	len = (_l);			\
337	if (remain < len) {		\
338		goto out;		\
339	}				\
340} while (0)
341
342#define INCP() do {			\
343	p += len;			\
344	remain -= len;			\
345} while (0)
346
347	remain = datalen;
348	p = data;
349
350	CHECKLEN(ENC_MAGIC_LEN);
351	err = check_magic(p);
352	if (err)
353		goto out;
354	memcpy(ep->magic, p, ENC_MAGIC_LEN);
355	INCP();
356
357	CHECKLEN(1);
358	ep->seed = *p;
359	INCP();
360
361	CHECKLEN(sizeof(uint32_t));
362	prod_len = get_be32(p);
363	if (prod_len > ENC_PRODUCT_LEN)
364		goto out;
365	INCP();
366
367	CHECKLEN(prod_len);
368	memcpy(ep->product, p, prod_len);
369	INCP();
370
371	CHECKLEN(sizeof(uint32_t));
372	ver_len = get_be32(p);
373	if (ver_len > ENC_VERSION_LEN)
374		goto out;
375	INCP();
376
377	CHECKLEN(ver_len);
378	memcpy(ep->version, p, ver_len);
379	INCP();
380
381	CHECKLEN(sizeof(uint32_t));
382	ep->datalen = get_be32(p);
383	INCP();
384
385	/* decrypt data */
386	CHECKLEN(ep->datalen);
387	err = bcrypt_buf(ep->version[0], ep->key, p, data, ep->datalen,
388			 ep->longstate);
389	if (err)
390		goto out;
391	INCP();
392
393	CHECKLEN(sizeof(uint32_t));
394	ep->csum = get_be32(p);
395	INCP();
396
397	csum = buffalo_csum(ep->datalen, data, ep->datalen);
398	if (csum != ep->csum)
399		goto out;
400
401	/* decrypt product name */
402	err = bcrypt_buf(ep->product[0], ep->key, ep->version, ep->version,
403			 ver_len, ep->longstate);
404	if (err)
405		goto out;
406
407	/* decrypt version */
408	err = bcrypt_buf(ep->seed, ep->key, ep->product, ep->product, prod_len,
409			 ep->longstate);
410	if (err)
411		goto out;
412
413	ret = 0;
414out:
415	return ret;
416
417#undef CHECKLEN
418#undef INCP
419}
420
421ssize_t get_file_size(char *name)
422{
423	struct stat st;
424	int err;
425
426	err = stat(name, &st);
427	if (err)
428		return -1;
429
430	return st.st_size;
431}
432
433int read_file_to_buf(char *name, void *buf, ssize_t buflen)
434{
435	FILE *f;
436	size_t done;
437	int ret = -1;
438
439	f = fopen(name, "r");
440	if (f == NULL)
441		goto out;
442
443	errno = 0;
444	done = fread(buf, buflen, 1, f);
445	if (done != 1)
446		goto close;
447
448	ret = 0;
449
450close:
451	fclose(f);
452out:
453	return ret;
454}
455
456int write_buf_to_file(char *name, void *buf, ssize_t buflen)
457{
458	FILE *f;
459	size_t done;
460	int ret = -1;
461
462	f = fopen(name, "w");
463	if (f == NULL)
464		goto out;
465
466	errno = 0;
467	done = fwrite(buf, buflen, 1, f);
468	if (done != 1)
469		goto close;
470
471	ret = 0;
472
473close:
474	fflush(f);
475	fclose(f);
476	if (ret)
477		unlink(name);
478out:
479	return ret;
480}
481