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44c09535 AT |
1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* | |
3 | * Module sysfs support | |
4 | * | |
5 | * Copyright (C) 2008 Rusty Russell | |
6 | */ | |
7 | ||
8 | #include <linux/module.h> | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/fs.h> | |
11 | #include <linux/sysfs.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/kallsyms.h> | |
14 | #include <linux/mutex.h> | |
15 | #include "internal.h" | |
16 | ||
17 | /* | |
18 | * /sys/module/foo/sections stuff | |
19 | * J. Corbet <corbet@lwn.net> | |
20 | */ | |
21 | #ifdef CONFIG_KALLSYMS | |
22 | struct module_sect_attr { | |
23 | struct bin_attribute battr; | |
24 | unsigned long address; | |
25 | }; | |
26 | ||
27 | struct module_sect_attrs { | |
28 | struct attribute_group grp; | |
29 | unsigned int nsections; | |
30 | struct module_sect_attr attrs[]; | |
31 | }; | |
32 | ||
33 | #define MODULE_SECT_READ_SIZE (3 /* "0x", "\n" */ + (BITS_PER_LONG / 4)) | |
34 | static ssize_t module_sect_read(struct file *file, struct kobject *kobj, | |
35 | struct bin_attribute *battr, | |
36 | char *buf, loff_t pos, size_t count) | |
37 | { | |
38 | struct module_sect_attr *sattr = | |
39 | container_of(battr, struct module_sect_attr, battr); | |
40 | char bounce[MODULE_SECT_READ_SIZE + 1]; | |
41 | size_t wrote; | |
42 | ||
43 | if (pos != 0) | |
44 | return -EINVAL; | |
45 | ||
46 | /* | |
47 | * Since we're a binary read handler, we must account for the | |
48 | * trailing NUL byte that sprintf will write: if "buf" is | |
49 | * too small to hold the NUL, or the NUL is exactly the last | |
50 | * byte, the read will look like it got truncated by one byte. | |
51 | * Since there is no way to ask sprintf nicely to not write | |
52 | * the NUL, we have to use a bounce buffer. | |
53 | */ | |
54 | wrote = scnprintf(bounce, sizeof(bounce), "0x%px\n", | |
55 | kallsyms_show_value(file->f_cred) | |
56 | ? (void *)sattr->address : NULL); | |
57 | count = min(count, wrote); | |
58 | memcpy(buf, bounce, count); | |
59 | ||
60 | return count; | |
61 | } | |
62 | ||
63 | static void free_sect_attrs(struct module_sect_attrs *sect_attrs) | |
64 | { | |
65 | unsigned int section; | |
66 | ||
67 | for (section = 0; section < sect_attrs->nsections; section++) | |
68 | kfree(sect_attrs->attrs[section].battr.attr.name); | |
69 | kfree(sect_attrs); | |
70 | } | |
71 | ||
72 | static void add_sect_attrs(struct module *mod, const struct load_info *info) | |
73 | { | |
74 | unsigned int nloaded = 0, i, size[2]; | |
75 | struct module_sect_attrs *sect_attrs; | |
76 | struct module_sect_attr *sattr; | |
77 | struct bin_attribute **gattr; | |
78 | ||
79 | /* Count loaded sections and allocate structures */ | |
80 | for (i = 0; i < info->hdr->e_shnum; i++) | |
81 | if (!sect_empty(&info->sechdrs[i])) | |
82 | nloaded++; | |
83 | size[0] = ALIGN(struct_size(sect_attrs, attrs, nloaded), | |
84 | sizeof(sect_attrs->grp.bin_attrs[0])); | |
85 | size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.bin_attrs[0]); | |
86 | sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL); | |
87 | if (!sect_attrs) | |
88 | return; | |
89 | ||
90 | /* Setup section attributes. */ | |
91 | sect_attrs->grp.name = "sections"; | |
92 | sect_attrs->grp.bin_attrs = (void *)sect_attrs + size[0]; | |
93 | ||
94 | sect_attrs->nsections = 0; | |
95 | sattr = §_attrs->attrs[0]; | |
96 | gattr = §_attrs->grp.bin_attrs[0]; | |
97 | for (i = 0; i < info->hdr->e_shnum; i++) { | |
98 | Elf_Shdr *sec = &info->sechdrs[i]; | |
99 | ||
100 | if (sect_empty(sec)) | |
101 | continue; | |
102 | sysfs_bin_attr_init(&sattr->battr); | |
103 | sattr->address = sec->sh_addr; | |
104 | sattr->battr.attr.name = | |
105 | kstrdup(info->secstrings + sec->sh_name, GFP_KERNEL); | |
106 | if (!sattr->battr.attr.name) | |
107 | goto out; | |
108 | sect_attrs->nsections++; | |
109 | sattr->battr.read = module_sect_read; | |
110 | sattr->battr.size = MODULE_SECT_READ_SIZE; | |
111 | sattr->battr.attr.mode = 0400; | |
112 | *(gattr++) = &(sattr++)->battr; | |
113 | } | |
114 | *gattr = NULL; | |
115 | ||
116 | if (sysfs_create_group(&mod->mkobj.kobj, §_attrs->grp)) | |
117 | goto out; | |
118 | ||
119 | mod->sect_attrs = sect_attrs; | |
120 | return; | |
121 | out: | |
122 | free_sect_attrs(sect_attrs); | |
123 | } | |
124 | ||
125 | static void remove_sect_attrs(struct module *mod) | |
126 | { | |
127 | if (mod->sect_attrs) { | |
128 | sysfs_remove_group(&mod->mkobj.kobj, | |
129 | &mod->sect_attrs->grp); | |
130 | /* | |
131 | * We are positive that no one is using any sect attrs | |
132 | * at this point. Deallocate immediately. | |
133 | */ | |
134 | free_sect_attrs(mod->sect_attrs); | |
135 | mod->sect_attrs = NULL; | |
136 | } | |
137 | } | |
138 | ||
139 | /* | |
140 | * /sys/module/foo/notes/.section.name gives contents of SHT_NOTE sections. | |
141 | */ | |
142 | ||
143 | struct module_notes_attrs { | |
144 | struct kobject *dir; | |
145 | unsigned int notes; | |
ea0b0bce | 146 | struct bin_attribute attrs[] __counted_by(notes); |
44c09535 AT |
147 | }; |
148 | ||
149 | static ssize_t module_notes_read(struct file *filp, struct kobject *kobj, | |
150 | struct bin_attribute *bin_attr, | |
151 | char *buf, loff_t pos, size_t count) | |
152 | { | |
153 | /* | |
154 | * The caller checked the pos and count against our size. | |
155 | */ | |
156 | memcpy(buf, bin_attr->private + pos, count); | |
157 | return count; | |
158 | } | |
159 | ||
160 | static void free_notes_attrs(struct module_notes_attrs *notes_attrs, | |
161 | unsigned int i) | |
162 | { | |
163 | if (notes_attrs->dir) { | |
164 | while (i-- > 0) | |
165 | sysfs_remove_bin_file(notes_attrs->dir, | |
166 | ¬es_attrs->attrs[i]); | |
167 | kobject_put(notes_attrs->dir); | |
168 | } | |
169 | kfree(notes_attrs); | |
170 | } | |
171 | ||
172 | static void add_notes_attrs(struct module *mod, const struct load_info *info) | |
173 | { | |
174 | unsigned int notes, loaded, i; | |
175 | struct module_notes_attrs *notes_attrs; | |
176 | struct bin_attribute *nattr; | |
177 | ||
178 | /* failed to create section attributes, so can't create notes */ | |
179 | if (!mod->sect_attrs) | |
180 | return; | |
181 | ||
182 | /* Count notes sections and allocate structures. */ | |
183 | notes = 0; | |
184 | for (i = 0; i < info->hdr->e_shnum; i++) | |
185 | if (!sect_empty(&info->sechdrs[i]) && | |
186 | info->sechdrs[i].sh_type == SHT_NOTE) | |
187 | ++notes; | |
188 | ||
189 | if (notes == 0) | |
190 | return; | |
191 | ||
192 | notes_attrs = kzalloc(struct_size(notes_attrs, attrs, notes), | |
193 | GFP_KERNEL); | |
194 | if (!notes_attrs) | |
195 | return; | |
196 | ||
197 | notes_attrs->notes = notes; | |
198 | nattr = ¬es_attrs->attrs[0]; | |
199 | for (loaded = i = 0; i < info->hdr->e_shnum; ++i) { | |
200 | if (sect_empty(&info->sechdrs[i])) | |
201 | continue; | |
202 | if (info->sechdrs[i].sh_type == SHT_NOTE) { | |
203 | sysfs_bin_attr_init(nattr); | |
204 | nattr->attr.name = mod->sect_attrs->attrs[loaded].battr.attr.name; | |
205 | nattr->attr.mode = 0444; | |
206 | nattr->size = info->sechdrs[i].sh_size; | |
207 | nattr->private = (void *)info->sechdrs[i].sh_addr; | |
208 | nattr->read = module_notes_read; | |
209 | ++nattr; | |
210 | } | |
211 | ++loaded; | |
212 | } | |
213 | ||
214 | notes_attrs->dir = kobject_create_and_add("notes", &mod->mkobj.kobj); | |
215 | if (!notes_attrs->dir) | |
216 | goto out; | |
217 | ||
218 | for (i = 0; i < notes; ++i) | |
219 | if (sysfs_create_bin_file(notes_attrs->dir, | |
220 | ¬es_attrs->attrs[i])) | |
221 | goto out; | |
222 | ||
223 | mod->notes_attrs = notes_attrs; | |
224 | return; | |
225 | ||
226 | out: | |
227 | free_notes_attrs(notes_attrs, i); | |
228 | } | |
229 | ||
230 | static void remove_notes_attrs(struct module *mod) | |
231 | { | |
232 | if (mod->notes_attrs) | |
233 | free_notes_attrs(mod->notes_attrs, mod->notes_attrs->notes); | |
234 | } | |
235 | ||
236 | #else /* !CONFIG_KALLSYMS */ | |
237 | static inline void add_sect_attrs(struct module *mod, const struct load_info *info) { } | |
238 | static inline void remove_sect_attrs(struct module *mod) { } | |
239 | static inline void add_notes_attrs(struct module *mod, const struct load_info *info) { } | |
240 | static inline void remove_notes_attrs(struct module *mod) { } | |
241 | #endif /* CONFIG_KALLSYMS */ | |
242 | ||
243 | static void del_usage_links(struct module *mod) | |
244 | { | |
245 | #ifdef CONFIG_MODULE_UNLOAD | |
246 | struct module_use *use; | |
247 | ||
248 | mutex_lock(&module_mutex); | |
249 | list_for_each_entry(use, &mod->target_list, target_list) | |
250 | sysfs_remove_link(use->target->holders_dir, mod->name); | |
251 | mutex_unlock(&module_mutex); | |
252 | #endif | |
253 | } | |
254 | ||
255 | static int add_usage_links(struct module *mod) | |
256 | { | |
257 | int ret = 0; | |
258 | #ifdef CONFIG_MODULE_UNLOAD | |
259 | struct module_use *use; | |
260 | ||
261 | mutex_lock(&module_mutex); | |
262 | list_for_each_entry(use, &mod->target_list, target_list) { | |
263 | ret = sysfs_create_link(use->target->holders_dir, | |
264 | &mod->mkobj.kobj, mod->name); | |
265 | if (ret) | |
266 | break; | |
267 | } | |
268 | mutex_unlock(&module_mutex); | |
269 | if (ret) | |
270 | del_usage_links(mod); | |
271 | #endif | |
272 | return ret; | |
273 | } | |
274 | ||
275 | static void module_remove_modinfo_attrs(struct module *mod, int end) | |
276 | { | |
277 | struct module_attribute *attr; | |
278 | int i; | |
279 | ||
280 | for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) { | |
281 | if (end >= 0 && i > end) | |
282 | break; | |
283 | /* pick a field to test for end of list */ | |
284 | if (!attr->attr.name) | |
285 | break; | |
286 | sysfs_remove_file(&mod->mkobj.kobj, &attr->attr); | |
287 | if (attr->free) | |
288 | attr->free(mod); | |
289 | } | |
290 | kfree(mod->modinfo_attrs); | |
291 | } | |
292 | ||
293 | static int module_add_modinfo_attrs(struct module *mod) | |
294 | { | |
295 | struct module_attribute *attr; | |
296 | struct module_attribute *temp_attr; | |
297 | int error = 0; | |
298 | int i; | |
299 | ||
300 | mod->modinfo_attrs = kzalloc((sizeof(struct module_attribute) * | |
301 | (modinfo_attrs_count + 1)), | |
302 | GFP_KERNEL); | |
303 | if (!mod->modinfo_attrs) | |
304 | return -ENOMEM; | |
305 | ||
306 | temp_attr = mod->modinfo_attrs; | |
307 | for (i = 0; (attr = modinfo_attrs[i]); i++) { | |
308 | if (!attr->test || attr->test(mod)) { | |
309 | memcpy(temp_attr, attr, sizeof(*temp_attr)); | |
310 | sysfs_attr_init(&temp_attr->attr); | |
311 | error = sysfs_create_file(&mod->mkobj.kobj, | |
312 | &temp_attr->attr); | |
313 | if (error) | |
314 | goto error_out; | |
315 | ++temp_attr; | |
316 | } | |
317 | } | |
318 | ||
319 | return 0; | |
320 | ||
321 | error_out: | |
322 | if (i > 0) | |
323 | module_remove_modinfo_attrs(mod, --i); | |
324 | else | |
325 | kfree(mod->modinfo_attrs); | |
326 | return error; | |
327 | } | |
328 | ||
329 | static void mod_kobject_put(struct module *mod) | |
330 | { | |
331 | DECLARE_COMPLETION_ONSTACK(c); | |
332 | ||
333 | mod->mkobj.kobj_completion = &c; | |
334 | kobject_put(&mod->mkobj.kobj); | |
335 | wait_for_completion(&c); | |
336 | } | |
337 | ||
338 | static int mod_sysfs_init(struct module *mod) | |
339 | { | |
340 | int err; | |
341 | struct kobject *kobj; | |
342 | ||
3cd60866 | 343 | if (!module_kset) { |
44c09535 AT |
344 | pr_err("%s: module sysfs not initialized\n", mod->name); |
345 | err = -EINVAL; | |
346 | goto out; | |
347 | } | |
348 | ||
349 | kobj = kset_find_obj(module_kset, mod->name); | |
350 | if (kobj) { | |
351 | pr_err("%s: module is already loaded\n", mod->name); | |
352 | kobject_put(kobj); | |
353 | err = -EINVAL; | |
354 | goto out; | |
355 | } | |
356 | ||
357 | mod->mkobj.mod = mod; | |
358 | ||
359 | memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj)); | |
360 | mod->mkobj.kobj.kset = module_kset; | |
361 | err = kobject_init_and_add(&mod->mkobj.kobj, &module_ktype, NULL, | |
362 | "%s", mod->name); | |
363 | if (err) | |
364 | mod_kobject_put(mod); | |
365 | ||
366 | out: | |
367 | return err; | |
368 | } | |
369 | ||
370 | int mod_sysfs_setup(struct module *mod, | |
371 | const struct load_info *info, | |
372 | struct kernel_param *kparam, | |
373 | unsigned int num_params) | |
374 | { | |
375 | int err; | |
376 | ||
377 | err = mod_sysfs_init(mod); | |
378 | if (err) | |
379 | goto out; | |
380 | ||
381 | mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj); | |
382 | if (!mod->holders_dir) { | |
383 | err = -ENOMEM; | |
384 | goto out_unreg; | |
385 | } | |
386 | ||
387 | err = module_param_sysfs_setup(mod, kparam, num_params); | |
388 | if (err) | |
389 | goto out_unreg_holders; | |
390 | ||
391 | err = module_add_modinfo_attrs(mod); | |
392 | if (err) | |
393 | goto out_unreg_param; | |
394 | ||
395 | err = add_usage_links(mod); | |
396 | if (err) | |
397 | goto out_unreg_modinfo_attrs; | |
398 | ||
399 | add_sect_attrs(mod, info); | |
400 | add_notes_attrs(mod, info); | |
401 | ||
402 | return 0; | |
403 | ||
404 | out_unreg_modinfo_attrs: | |
405 | module_remove_modinfo_attrs(mod, -1); | |
406 | out_unreg_param: | |
407 | module_param_sysfs_remove(mod); | |
408 | out_unreg_holders: | |
409 | kobject_put(mod->holders_dir); | |
410 | out_unreg: | |
411 | mod_kobject_put(mod); | |
412 | out: | |
413 | return err; | |
414 | } | |
415 | ||
416 | static void mod_sysfs_fini(struct module *mod) | |
417 | { | |
418 | remove_notes_attrs(mod); | |
419 | remove_sect_attrs(mod); | |
420 | mod_kobject_put(mod); | |
421 | } | |
422 | ||
423 | void mod_sysfs_teardown(struct module *mod) | |
424 | { | |
425 | del_usage_links(mod); | |
426 | module_remove_modinfo_attrs(mod, -1); | |
427 | module_param_sysfs_remove(mod); | |
428 | kobject_put(mod->mkobj.drivers_dir); | |
429 | kobject_put(mod->holders_dir); | |
430 | mod_sysfs_fini(mod); | |
431 | } | |
432 | ||
433 | void init_param_lock(struct module *mod) | |
434 | { | |
435 | mutex_init(&mod->param_lock); | |
436 | } |