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
22struct module_sect_attr {
23 struct bin_attribute battr;
24 unsigned long address;
25};
26
27struct 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))
34static 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
63static 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
72static 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 = &sect_attrs->attrs[0];
96 gattr = &sect_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: &sect_attrs->grp))
117 goto out;
118
119 mod->sect_attrs = sect_attrs;
120 return;
121out:
122 free_sect_attrs(sect_attrs);
123}
124
125static 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
143struct module_notes_attrs {
144 struct kobject *dir;
145 unsigned int notes;
146 struct bin_attribute attrs[] __counted_by(notes);
147};
148
149static 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
160static 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: &notes_attrs->attrs[i]);
167 kobject_put(kobj: notes_attrs->dir);
168 }
169 kfree(objp: notes_attrs);
170}
171
172static 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 = &notes_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: &notes_attrs->attrs[i]))
221 goto out;
222
223 mod->notes_attrs = notes_attrs;
224 return;
225
226out:
227 free_notes_attrs(notes_attrs, i);
228}
229
230static 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 */
237static inline void add_sect_attrs(struct module *mod, const struct load_info *info) { }
238static inline void remove_sect_attrs(struct module *mod) { }
239static inline void add_notes_attrs(struct module *mod, const struct load_info *info) { }
240static inline void remove_notes_attrs(struct module *mod) { }
241#endif /* CONFIG_KALLSYMS */
242
243static 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
255static 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
275static 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
293static 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
321error_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
329static 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
338static 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
366out:
367 return err;
368}
369
370int 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
404out_unreg_modinfo_attrs:
405 module_remove_modinfo_attrs(mod, end: -1);
406out_unreg_param:
407 module_param_sysfs_remove(mod);
408out_unreg_holders:
409 kobject_put(kobj: mod->holders_dir);
410out_unreg:
411 mod_kobject_put(mod);
412out:
413 return err;
414}
415
416static 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
423void 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
433void init_param_lock(struct module *mod)
434{
435 mutex_init(&mod->param_lock);
436}
437

source code of linux/kernel/module/sysfs.c