1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * LZO decompressor for the Linux kernel. Code borrowed from the lzo
4 * implementation by Markus Franz Xaver Johannes Oberhumer.
5 *
6 * Linux kernel adaptation:
7 * Copyright (C) 2009
8 * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
9 *
10 * Original code:
11 * Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
12 * All Rights Reserved.
13 *
14 * Markus F.X.J. Oberhumer
15 * <markus@oberhumer.com>
16 * http://www.oberhumer.com/opensource/lzop/
17 */
18
19#ifdef STATIC
20#define PREBOOT
21#include "lzo/lzo1x_decompress_safe.c"
22#else
23#include <linux/decompress/unlzo.h>
24#endif
25
26#include <linux/types.h>
27#include <linux/lzo.h>
28#include <linux/decompress/mm.h>
29
30#include <linux/compiler.h>
31#include <asm/unaligned.h>
32
33static const unsigned char lzop_magic[] = {
34	0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };
35
36#define LZO_BLOCK_SIZE        (256*1024l)
37#define HEADER_HAS_FILTER      0x00000800L
38#define HEADER_SIZE_MIN       (9 + 7     + 4 + 8     + 1       + 4)
39#define HEADER_SIZE_MAX       (9 + 7 + 1 + 8 + 8 + 4 + 1 + 255 + 4)
40
41STATIC inline long INIT parse_header(u8 *input, long *skip, long in_len)
42{
43	int l;
44	u8 *parse = input;
45	u8 *end = input + in_len;
46	u8 level = 0;
47	u16 version;
48
49	/*
50	 * Check that there's enough input to possibly have a valid header.
51	 * Then it is possible to parse several fields until the minimum
52	 * size may have been used.
53	 */
54	if (in_len < HEADER_SIZE_MIN)
55		return 0;
56
57	/* read magic: 9 first bits */
58	for (l = 0; l < 9; l++) {
59		if (*parse++ != lzop_magic[l])
60			return 0;
61	}
62	/* get version (2bytes), skip library version (2),
63	 * 'need to be extracted' version (2) and
64	 * method (1) */
65	version = get_unaligned_be16(parse);
66	parse += 7;
67	if (version >= 0x0940)
68		level = *parse++;
69	if (get_unaligned_be32(parse) & HEADER_HAS_FILTER)
70		parse += 8; /* flags + filter info */
71	else
72		parse += 4; /* flags */
73
74	/*
75	 * At least mode, mtime_low, filename length, and checksum must
76	 * be left to be parsed. If also mtime_high is present, it's OK
77	 * because the next input buffer check is after reading the
78	 * filename length.
79	 */
80	if (end - parse < 8 + 1 + 4)
81		return 0;
82
83	/* skip mode and mtime_low */
84	parse += 8;
85	if (version >= 0x0940)
86		parse += 4;	/* skip mtime_high */
87
88	l = *parse++;
89	/* don't care about the file name, and skip checksum */
90	if (end - parse < l + 4)
91		return 0;
92	parse += l + 4;
93
94	*skip = parse - input;
95	return 1;
96}
97
98STATIC int INIT unlzo(u8 *input, long in_len,
99				long (*fill)(void *, unsigned long),
100				long (*flush)(void *, unsigned long),
101				u8 *output, long *posp,
102				void (*error) (char *x))
103{
104	u8 r = 0;
105	long skip = 0;
106	u32 src_len, dst_len;
107	size_t tmp;
108	u8 *in_buf, *in_buf_save, *out_buf;
109	int ret = -1;
110
111	if (output) {
112		out_buf = output;
113	} else if (!flush) {
114		error("NULL output pointer and no flush function provided");
115		goto exit;
116	} else {
117		out_buf = malloc(LZO_BLOCK_SIZE);
118		if (!out_buf) {
119			error("Could not allocate output buffer");
120			goto exit;
121		}
122	}
123
124	if (input && fill) {
125		error("Both input pointer and fill function provided, don't know what to do");
126		goto exit_1;
127	} else if (input) {
128		in_buf = input;
129	} else if (!fill) {
130		error("NULL input pointer and missing fill function");
131		goto exit_1;
132	} else {
133		in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE));
134		if (!in_buf) {
135			error("Could not allocate input buffer");
136			goto exit_1;
137		}
138	}
139	in_buf_save = in_buf;
140
141	if (posp)
142		*posp = 0;
143
144	if (fill) {
145		/*
146		 * Start from in_buf + HEADER_SIZE_MAX to make it possible
147		 * to use memcpy() to copy the unused data to the beginning
148		 * of the buffer. This way memmove() isn't needed which
149		 * is missing from pre-boot environments of most archs.
150		 */
151		in_buf += HEADER_SIZE_MAX;
152		in_len = fill(in_buf, HEADER_SIZE_MAX);
153	}
154
155	if (!parse_header(in_buf, &skip, in_len)) {
156		error("invalid header");
157		goto exit_2;
158	}
159	in_buf += skip;
160	in_len -= skip;
161
162	if (fill) {
163		/* Move the unused data to the beginning of the buffer. */
164		memcpy(in_buf_save, in_buf, in_len);
165		in_buf = in_buf_save;
166	}
167
168	if (posp)
169		*posp = skip;
170
171	for (;;) {
172		/* read uncompressed block size */
173		if (fill && in_len < 4) {
174			skip = fill(in_buf + in_len, 4 - in_len);
175			if (skip > 0)
176				in_len += skip;
177		}
178		if (in_len < 4) {
179			error("file corrupted");
180			goto exit_2;
181		}
182		dst_len = get_unaligned_be32(in_buf);
183		in_buf += 4;
184		in_len -= 4;
185
186		/* exit if last block */
187		if (dst_len == 0) {
188			if (posp)
189				*posp += 4;
190			break;
191		}
192
193		if (dst_len > LZO_BLOCK_SIZE) {
194			error("dest len longer than block size");
195			goto exit_2;
196		}
197
198		/* read compressed block size, and skip block checksum info */
199		if (fill && in_len < 8) {
200			skip = fill(in_buf + in_len, 8 - in_len);
201			if (skip > 0)
202				in_len += skip;
203		}
204		if (in_len < 8) {
205			error("file corrupted");
206			goto exit_2;
207		}
208		src_len = get_unaligned_be32(in_buf);
209		in_buf += 8;
210		in_len -= 8;
211
212		if (src_len <= 0 || src_len > dst_len) {
213			error("file corrupted");
214			goto exit_2;
215		}
216
217		/* decompress */
218		if (fill && in_len < src_len) {
219			skip = fill(in_buf + in_len, src_len - in_len);
220			if (skip > 0)
221				in_len += skip;
222		}
223		if (in_len < src_len) {
224			error("file corrupted");
225			goto exit_2;
226		}
227		tmp = dst_len;
228
229		/* When the input data is not compressed at all,
230		 * lzo1x_decompress_safe will fail, so call memcpy()
231		 * instead */
232		if (unlikely(dst_len == src_len))
233			memcpy(out_buf, in_buf, src_len);
234		else {
235			r = lzo1x_decompress_safe((u8 *) in_buf, src_len,
236						out_buf, &tmp);
237
238			if (r != LZO_E_OK || dst_len != tmp) {
239				error("Compressed data violation");
240				goto exit_2;
241			}
242		}
243
244		if (flush && flush(out_buf, dst_len) != dst_len)
245			goto exit_2;
246		if (output)
247			out_buf += dst_len;
248		if (posp)
249			*posp += src_len + 12;
250
251		in_buf += src_len;
252		in_len -= src_len;
253		if (fill) {
254			/*
255			 * If there happens to still be unused data left in
256			 * in_buf, move it to the beginning of the buffer.
257			 * Use a loop to avoid memmove() dependency.
258			 */
259			if (in_len > 0)
260				for (skip = 0; skip < in_len; ++skip)
261					in_buf_save[skip] = in_buf[skip];
262			in_buf = in_buf_save;
263		}
264	}
265
266	ret = 0;
267exit_2:
268	if (!input)
269		free(in_buf_save);
270exit_1:
271	if (!output)
272		free(out_buf);
273exit:
274	return ret;
275}
276
277#ifdef PREBOOT
278STATIC int INIT __decompress(unsigned char *buf, long len,
279			   long (*fill)(void*, unsigned long),
280			   long (*flush)(void*, unsigned long),
281			   unsigned char *out_buf, long olen,
282			   long *pos,
283			   void (*error)(char *x))
284{
285	return unlzo(buf, len, fill, flush, out_buf, pos, error);
286}
287#endif
288