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(buf: bounce, size: sizeof(bounce), fmt: "0x%px\n" , |
55 | kallsyms_show_value(cred: 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(objp: sect_attrs->attrs[section].battr.attr.name); |
69 | kfree(objp: 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(sect: &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: 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(sect: sec)) |
101 | continue; |
102 | sysfs_bin_attr_init(&sattr->battr); |
103 | sattr->address = sec->sh_addr; |
104 | sattr->battr.attr.name = |
105 | kstrdup(s: 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(kobj: &mod->mkobj.kobj, grp: §_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(kobj: &mod->mkobj.kobj, |
129 | grp: &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(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; |
146 | struct bin_attribute attrs[] __counted_by(notes); |
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(kobj: notes_attrs->dir, |
166 | attr: ¬es_attrs->attrs[i]); |
167 | kobject_put(kobj: notes_attrs->dir); |
168 | } |
169 | kfree(objp: 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(sect: &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(sect: &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(name: "notes" , parent: &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(kobj: notes_attrs->dir, |
220 | attr: ¬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(notes_attrs: mod->notes_attrs, i: 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(kobj: use->target->holders_dir, name: mod->name); |
251 | mutex_unlock(lock: &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(kobj: use->target->holders_dir, |
264 | target: &mod->mkobj.kobj, name: mod->name); |
265 | if (ret) |
266 | break; |
267 | } |
268 | mutex_unlock(lock: &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(kobj: &mod->mkobj.kobj, attr: &attr->attr); |
287 | if (attr->free) |
288 | attr->free(mod); |
289 | } |
290 | kfree(objp: 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(size: (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(kobj: &mod->mkobj.kobj, |
312 | attr: &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, end: --i); |
324 | else |
325 | kfree(objp: 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(kobj: &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 | |
343 | if (!module_kset) { |
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(kobj: &mod->mkobj.kobj, ktype: &module_ktype, NULL, |
362 | fmt: "%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(name: "holders" , parent: &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, end: -1); |
406 | out_unreg_param: |
407 | module_param_sysfs_remove(mod); |
408 | out_unreg_holders: |
409 | kobject_put(kobj: 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, end: -1); |
427 | module_param_sysfs_remove(mod); |
428 | kobject_put(kobj: mod->mkobj.drivers_dir); |
429 | kobject_put(kobj: 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 | } |
437 | |