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