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 
33 static 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 
parse_header(u8 * input,long * skip,long in_len)41 STATIC 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 
unlzo(u8 * input,long in_len,long (* fill)(void *,unsigned long),long (* flush)(void *,unsigned long),u8 * output,long * posp,void (* error)(char * x))97 STATIC 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;
266 exit_2:
267 	if (!input)
268 		free(in_buf_save);
269 exit_1:
270 	if (!output)
271 		free(out_buf);
272 exit:
273 	return ret;
274 }
275 
276 #ifdef PREBOOT
__decompress(unsigned char * buf,long len,long (* fill)(void *,unsigned long),long (* flush)(void *,unsigned long),unsigned char * out_buf,long olen,long * pos,void (* error)(char * x))277 STATIC 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