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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 "module-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 | #ifdef 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 = kmalloc(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 decompresser: %d\n", rc); | |
110 | retval = -EINVAL; | |
111 | goto out; | |
112 | } | |
113 | ||
114 | do { | |
115 | struct page *page = module_get_next_page(info); | |
116 | if (!page) { | |
117 | retval = -ENOMEM; | |
118 | goto out_inflate_end; | |
119 | } | |
120 | ||
121 | s.next_out = kmap(page); | |
122 | s.avail_out = PAGE_SIZE; | |
123 | rc = zlib_inflate(&s, 0); | |
124 | kunmap(page); | |
125 | ||
126 | new_size += PAGE_SIZE - s.avail_out; | |
127 | } while (rc == Z_OK); | |
128 | ||
129 | if (rc != Z_STREAM_END) { | |
130 | pr_err("decompression failed with status %d\n", rc); | |
131 | retval = -EINVAL; | |
132 | goto out_inflate_end; | |
133 | } | |
134 | ||
135 | retval = new_size; | |
136 | ||
137 | out_inflate_end: | |
138 | zlib_inflateEnd(&s); | |
139 | out: | |
140 | kfree(s.workspace); | |
141 | return retval; | |
142 | } | |
143 | #elif CONFIG_MODULE_COMPRESS_XZ | |
144 | #include <linux/xz.h> | |
145 | #define MODULE_COMPRESSION xz | |
146 | #define MODULE_DECOMPRESS_FN module_xz_decompress | |
147 | ||
148 | static ssize_t module_xz_decompress(struct load_info *info, | |
149 | const void *buf, size_t size) | |
150 | { | |
151 | static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 }; | |
152 | struct xz_dec *xz_dec; | |
153 | struct xz_buf xz_buf; | |
154 | enum xz_ret xz_ret; | |
155 | size_t new_size = 0; | |
156 | ssize_t retval; | |
157 | ||
158 | if (size < sizeof(signature) || | |
159 | memcmp(buf, signature, sizeof(signature))) { | |
160 | pr_err("not an xz compressed module\n"); | |
161 | return -EINVAL; | |
162 | } | |
163 | ||
164 | xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1); | |
165 | if (!xz_dec) | |
166 | return -ENOMEM; | |
167 | ||
168 | xz_buf.in_size = size; | |
169 | xz_buf.in = buf; | |
170 | xz_buf.in_pos = 0; | |
171 | ||
172 | do { | |
173 | struct page *page = module_get_next_page(info); | |
174 | if (!page) { | |
175 | retval = -ENOMEM; | |
176 | goto out; | |
177 | } | |
178 | ||
179 | xz_buf.out = kmap(page); | |
180 | xz_buf.out_pos = 0; | |
181 | xz_buf.out_size = PAGE_SIZE; | |
182 | xz_ret = xz_dec_run(xz_dec, &xz_buf); | |
183 | kunmap(page); | |
184 | ||
185 | new_size += xz_buf.out_pos; | |
186 | } while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK); | |
187 | ||
188 | if (xz_ret != XZ_STREAM_END) { | |
189 | pr_err("decompression failed with status %d\n", xz_ret); | |
190 | retval = -EINVAL; | |
191 | goto out; | |
192 | } | |
193 | ||
194 | retval = new_size; | |
195 | ||
196 | out: | |
197 | xz_dec_end(xz_dec); | |
198 | return retval; | |
199 | } | |
200 | #else | |
201 | #error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS" | |
202 | #endif | |
203 | ||
204 | int module_decompress(struct load_info *info, const void *buf, size_t size) | |
205 | { | |
206 | unsigned int n_pages; | |
207 | ssize_t data_size; | |
208 | int error; | |
209 | ||
210 | /* | |
211 | * Start with number of pages twice as big as needed for | |
212 | * compressed data. | |
213 | */ | |
214 | n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2; | |
215 | error = module_extend_max_pages(info, n_pages); | |
216 | ||
217 | data_size = MODULE_DECOMPRESS_FN(info, buf, size); | |
218 | if (data_size < 0) { | |
219 | error = data_size; | |
220 | goto err; | |
221 | } | |
222 | ||
223 | info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL); | |
224 | if (!info->hdr) { | |
225 | error = -ENOMEM; | |
226 | goto err; | |
227 | } | |
228 | ||
229 | info->len = data_size; | |
230 | return 0; | |
231 | ||
232 | err: | |
233 | module_decompress_cleanup(info); | |
234 | return error; | |
235 | } | |
236 | ||
237 | void module_decompress_cleanup(struct load_info *info) | |
238 | { | |
239 | int i; | |
240 | ||
241 | if (info->hdr) | |
242 | vunmap(info->hdr); | |
243 | ||
244 | for (i = 0; i < info->used_pages; i++) | |
245 | __free_page(info->pages[i]); | |
246 | ||
247 | kvfree(info->pages); | |
248 | ||
249 | info->pages = NULL; | |
250 | info->max_pages = info->used_pages = 0; | |
251 | } | |
252 | ||
253 | static ssize_t compression_show(struct kobject *kobj, | |
254 | struct kobj_attribute *attr, char *buf) | |
255 | { | |
256 | return sysfs_emit(buf, "%s\n", __stringify(MODULE_COMPRESSION)); | |
257 | } | |
258 | static struct kobj_attribute module_compression_attr = __ATTR_RO(compression); | |
259 | ||
260 | static int __init module_decompress_sysfs_init(void) | |
261 | { | |
262 | int error; | |
263 | ||
264 | error = sysfs_create_file(&module_kset->kobj, | |
265 | &module_compression_attr.attr); | |
266 | if (error) | |
267 | pr_warn("Failed to create 'compression' attribute"); | |
268 | ||
269 | return 0; | |
270 | } | |
271 | late_initcall(module_decompress_sysfs_init); |