1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2021 Google LLC.
4 */
5
6 #include <linux/init.h>
7 #include <linux/highmem.h>
8 #include <linux/kobject.h>
9 #include <linux/mm.h>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/sysfs.h>
13 #include <linux/vmalloc.h>
14
15 #include "internal.h"
16
17 static int module_extend_max_pages(struct load_info *info, unsigned int extent)
18 {
19 struct page **new_pages;
20
21 new_pages = kvmalloc_array(info->max_pages + extent,
22 sizeof(info->pages), GFP_KERNEL);
23 if (!new_pages)
24 return -ENOMEM;
25
26 memcpy(new_pages, info->pages, info->max_pages * sizeof(info->pages));
27 kvfree(info->pages);
28 info->pages = new_pages;
29 info->max_pages += extent;
30
31 return 0;
32 }
33
34 static struct page *module_get_next_page(struct load_info *info)
35 {
36 struct page *page;
37 int error;
38
39 if (info->max_pages == info->used_pages) {
40 error = module_extend_max_pages(info, info->used_pages);
41 if (error)
42 return ERR_PTR(error);
43 }
44
45 page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
46 if (!page)
47 return ERR_PTR(-ENOMEM);
48
49 info->pages[info->used_pages++] = page;
50 return page;
51 }
52
53 #if defined(CONFIG_MODULE_COMPRESS_GZIP)
54 #include <linux/zlib.h>
55 #define MODULE_COMPRESSION gzip
56 #define MODULE_DECOMPRESS_FN module_gzip_decompress
57
58 /*
59 * Calculate length of the header which consists of signature, header
60 * flags, time stamp and operating system ID (10 bytes total), plus
61 * an optional filename.
62 */
63 static size_t module_gzip_header_len(const u8 *buf, size_t size)
64 {
65 const u8 signature[] = { 0x1f, 0x8b, 0x08 };
66 size_t len = 10;
67
68 if (size < len || memcmp(buf, signature, sizeof(signature)))
69 return 0;
70
71 if (buf[3] & 0x08) {
72 do {
73 /*
74 * If we can't find the end of the file name we must
75 * be dealing with a corrupted file.
76 */
77 if (len == size)
78 return 0;
79 } while (buf[len++] != '\0');
80 }
81
82 return len;
83 }
84
85 static ssize_t module_gzip_decompress(struct load_info *info,
86 const void *buf, size_t size)
87 {
88 struct z_stream_s s = { 0 };
89 size_t new_size = 0;
90 size_t gzip_hdr_len;
91 ssize_t retval;
92 int rc;
93
94 gzip_hdr_len = module_gzip_header_len(buf, size);
95 if (!gzip_hdr_len) {
96 pr_err("not a gzip compressed module\n");
97 return -EINVAL;
98 }
99
100 s.next_in = buf + gzip_hdr_len;
101 s.avail_in = size - gzip_hdr_len;
102
103 s.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
104 if (!s.workspace)
105 return -ENOMEM;
106
107 rc = zlib_inflateInit2(&s, -MAX_WBITS);
108 if (rc != Z_OK) {
109 pr_err("failed to initialize decompressor: %d\n", rc);
110 retval = -EINVAL;
111 goto out;
112 }
113
114 do {
115 struct page *page = module_get_next_page(info);
116
117 if (IS_ERR(page)) {
118 retval = PTR_ERR(page);
119 goto out_inflate_end;
120 }
121
122 s.next_out = kmap_local_page(page);
123 s.avail_out = PAGE_SIZE;
124 rc = zlib_inflate(&s, 0);
125 kunmap_local(s.next_out);
126
127 new_size += PAGE_SIZE - s.avail_out;
128 } while (rc == Z_OK);
129
130 if (rc != Z_STREAM_END) {
131 pr_err("decompression failed with status %d\n", rc);
132 retval = -EINVAL;
133 goto out_inflate_end;
134 }
135
136 retval = new_size;
137
138 out_inflate_end:
139 zlib_inflateEnd(&s);
140 out:
141 kvfree(s.workspace);
142 return retval;
143 }
144 #elif defined(CONFIG_MODULE_COMPRESS_XZ)
145 #include <linux/xz.h>
146 #define MODULE_COMPRESSION xz
147 #define MODULE_DECOMPRESS_FN module_xz_decompress
148
149 static ssize_t module_xz_decompress(struct load_info *info,
150 const void *buf, size_t size)
151 {
152 static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 };
153 struct xz_dec *xz_dec;
154 struct xz_buf xz_buf;
155 enum xz_ret xz_ret;
156 size_t new_size = 0;
157 ssize_t retval;
158
159 if (size < sizeof(signature) ||
160 memcmp(buf, signature, sizeof(signature))) {
161 pr_err("not an xz compressed module\n");
162 return -EINVAL;
163 }
164
165 xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1);
166 if (!xz_dec)
167 return -ENOMEM;
168
169 xz_buf.in_size = size;
170 xz_buf.in = buf;
171 xz_buf.in_pos = 0;
172
173 do {
174 struct page *page = module_get_next_page(info);
175
176 if (IS_ERR(page)) {
177 retval = PTR_ERR(page);
178 goto out;
179 }
180
181 xz_buf.out = kmap_local_page(page);
182 xz_buf.out_pos = 0;
183 xz_buf.out_size = PAGE_SIZE;
184 xz_ret = xz_dec_run(xz_dec, &xz_buf);
185 kunmap_local(xz_buf.out);
186
187 new_size += xz_buf.out_pos;
188 } while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK);
189
190 if (xz_ret != XZ_STREAM_END) {
191 pr_err("decompression failed with status %d\n", xz_ret);
192 retval = -EINVAL;
193 goto out;
194 }
195
196 retval = new_size;
197
198 out:
199 xz_dec_end(xz_dec);
200 return retval;
201 }
202 #elif defined(CONFIG_MODULE_COMPRESS_ZSTD)
203 #include <linux/zstd.h>
204 #define MODULE_COMPRESSION zstd
205 #define MODULE_DECOMPRESS_FN module_zstd_decompress
206
207 static ssize_t module_zstd_decompress(struct load_info *info,
208 const void *buf, size_t size)
209 {
210 static const u8 signature[] = { 0x28, 0xb5, 0x2f, 0xfd };
211 ZSTD_outBuffer zstd_dec;
212 ZSTD_inBuffer zstd_buf;
213 zstd_frame_header header;
214 size_t wksp_size;
215 void *wksp = NULL;
216 ZSTD_DStream *dstream;
217 size_t ret;
218 size_t new_size = 0;
219 int retval;
220
221 if (size < sizeof(signature) ||
222 memcmp(buf, signature, sizeof(signature))) {
223 pr_err("not a zstd compressed module\n");
224 return -EINVAL;
225 }
226
227 zstd_buf.src = buf;
228 zstd_buf.pos = 0;
229 zstd_buf.size = size;
230
231 ret = zstd_get_frame_header(&header, zstd_buf.src, zstd_buf.size);
232 if (ret != 0) {
233 pr_err("ZSTD-compressed data has an incomplete frame header\n");
234 retval = -EINVAL;
235 goto out;
236 }
237 if (header.windowSize > (1 << ZSTD_WINDOWLOG_MAX)) {
238 pr_err("ZSTD-compressed data has too large a window size\n");
239 retval = -EINVAL;
240 goto out;
241 }
242
243 wksp_size = zstd_dstream_workspace_bound(header.windowSize);
244 wksp = kvmalloc(wksp_size, GFP_KERNEL);
245 if (!wksp) {
246 retval = -ENOMEM;
247 goto out;
248 }
249
250 dstream = zstd_init_dstream(header.windowSize, wksp, wksp_size);
251 if (!dstream) {
252 pr_err("Can't initialize ZSTD stream\n");
253 retval = -ENOMEM;
254 goto out;
255 }
256
257 do {
258 struct page *page = module_get_next_page(info);
259
260 if (IS_ERR(page)) {
261 retval = PTR_ERR(page);
262 goto out;
263 }
264
265 zstd_dec.dst = kmap_local_page(page);
266 zstd_dec.pos = 0;
267 zstd_dec.size = PAGE_SIZE;
268
269 ret = zstd_decompress_stream(dstream, &zstd_dec, &zstd_buf);
270 kunmap_local(zstd_dec.dst);
271 retval = zstd_get_error_code(ret);
272 if (retval)
273 break;
274
275 new_size += zstd_dec.pos;
276 } while (zstd_dec.pos == PAGE_SIZE && ret != 0);
277
278 if (retval) {
279 pr_err("ZSTD-decompression failed with status %d\n", retval);
280 retval = -EINVAL;
281 goto out;
282 }
283
284 retval = new_size;
285
286 out:
287 kvfree(wksp);
288 return retval;
289 }
290 #else
291 #error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS"
292 #endif
293
294 int module_decompress(struct load_info *info, const void *buf, size_t size)
295 {
296 unsigned int n_pages;
297 ssize_t data_size;
298 int error;
299
300 #if defined(CONFIG_MODULE_STATS)
301 info->compressed_len = size;
302 #endif
303
304 /*
305 * Start with number of pages twice as big as needed for
306 * compressed data.
307 */
308 n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2;
309 error = module_extend_max_pages(info, n_pages);
310
311 data_size = MODULE_DECOMPRESS_FN(info, buf, size);
312 if (data_size < 0) {
313 error = data_size;
314 goto err;
315 }
316
317 info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL);
318 if (!info->hdr) {
319 error = -ENOMEM;
320 goto err;
321 }
322
323 info->len = data_size;
324 return 0;
325
326 err:
327 module_decompress_cleanup(info);
328 return error;
329 }
330
331 void module_decompress_cleanup(struct load_info *info)
332 {
333 int i;
334
335 if (info->hdr)
336 vunmap(info->hdr);
337
338 for (i = 0; i < info->used_pages; i++)
339 __free_page(info->pages[i]);
340
341 kvfree(info->pages);
342
343 info->pages = NULL;
344 info->max_pages = info->used_pages = 0;
345 }
346
347 #ifdef CONFIG_SYSFS
348 static ssize_t compression_show(struct kobject *kobj,
349 struct kobj_attribute *attr, char *buf)
350 {
351 return sysfs_emit(buf, __stringify(MODULE_COMPRESSION) "\n");
352 }
353
354 static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);
355
356 static int __init module_decompress_sysfs_init(void)
357 {
358 int error;
359
360 error = sysfs_create_file(&module_kset->kobj,
361 &module_compression_attr.attr);
362 if (error)
363 pr_warn("Failed to create 'compression' attribute");
364
365 return 0;
366 }
367 late_initcall(module_decompress_sysfs_init);
368 #endif
369
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.