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 int 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 int ret; 79 80 /* Count loaded sections and allocate structures */ 81 for (i = 0; i < info->hdr->e_shnum; i++) 82 if (!sect_empty(&info->sechdrs[i])) 83 nloaded++; 84 size[0] = ALIGN(struct_size(sect_attrs, attrs, nloaded), 85 sizeof(sect_attrs->grp.bin_attrs[0])); 86 size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.bin_attrs[0]); 87 sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL); 88 if (!sect_attrs) 89 return -ENOMEM; 90 91 /* Setup section attributes. */ 92 sect_attrs->grp.name = "sections"; 93 sect_attrs->grp.bin_attrs = (void *)sect_attrs + size[0]; 94 95 sect_attrs->nsections = 0; 96 sattr = §_attrs->attrs[0]; 97 gattr = §_attrs->grp.bin_attrs[0]; 98 for (i = 0; i < info->hdr->e_shnum; i++) { 99 Elf_Shdr *sec = &info->sechdrs[i]; 100 101 if (sect_empty(sec)) 102 continue; 103 sysfs_bin_attr_init(&sattr->battr); 104 sattr->address = sec->sh_addr; 105 sattr->battr.attr.name = 106 kstrdup(info->secstrings + sec->sh_name, GFP_KERNEL); 107 if (!sattr->battr.attr.name) { 108 ret = -ENOMEM; 109 goto out; 110 } 111 sect_attrs->nsections++; 112 sattr->battr.read = module_sect_read; 113 sattr->battr.size = MODULE_SECT_READ_SIZE; 114 sattr->battr.attr.mode = 0400; 115 *(gattr++) = &(sattr++)->battr; 116 } 117 *gattr = NULL; 118 119 ret = sysfs_create_group(&mod->mkobj.kobj, §_attrs->grp); 120 if (ret) 121 goto out; 122 123 mod->sect_attrs = sect_attrs; 124 return 0; 125 out: 126 free_sect_attrs(sect_attrs); 127 return ret; 128 } 129 130 static void remove_sect_attrs(struct module *mod) 131 { 132 if (mod->sect_attrs) { 133 sysfs_remove_group(&mod->mkobj.kobj, 134 &mod->sect_attrs->grp); 135 /* 136 * We are positive that no one is using any sect attrs 137 * at this point. Deallocate immediately. 138 */ 139 free_sect_attrs(mod->sect_attrs); 140 mod->sect_attrs = NULL; 141 } 142 } 143 144 /* 145 * /sys/module/foo/notes/.section.name gives contents of SHT_NOTE sections. 146 */ 147 148 struct module_notes_attrs { 149 struct kobject *dir; 150 unsigned int notes; 151 struct bin_attribute attrs[] __counted_by(notes); 152 }; 153 154 static void free_notes_attrs(struct module_notes_attrs *notes_attrs, 155 unsigned int i) 156 { 157 if (notes_attrs->dir) { 158 while (i-- > 0) 159 sysfs_remove_bin_file(notes_attrs->dir, 160 ¬es_attrs->attrs[i]); 161 kobject_put(notes_attrs->dir); 162 } 163 kfree(notes_attrs); 164 } 165 166 static int add_notes_attrs(struct module *mod, const struct load_info *info) 167 { 168 unsigned int notes, loaded, i; 169 struct module_notes_attrs *notes_attrs; 170 struct bin_attribute *nattr; 171 int ret; 172 173 /* Count notes sections and allocate structures. */ 174 notes = 0; 175 for (i = 0; i < info->hdr->e_shnum; i++) 176 if (!sect_empty(&info->sechdrs[i]) && 177 info->sechdrs[i].sh_type == SHT_NOTE) 178 ++notes; 179 180 if (notes == 0) 181 return 0; 182 183 notes_attrs = kzalloc(struct_size(notes_attrs, attrs, notes), 184 GFP_KERNEL); 185 if (!notes_attrs) 186 return -ENOMEM; 187 188 notes_attrs->notes = notes; 189 nattr = ¬es_attrs->attrs[0]; 190 for (loaded = i = 0; i < info->hdr->e_shnum; ++i) { 191 if (sect_empty(&info->sechdrs[i])) 192 continue; 193 if (info->sechdrs[i].sh_type == SHT_NOTE) { 194 sysfs_bin_attr_init(nattr); 195 nattr->attr.name = mod->sect_attrs->attrs[loaded].battr.attr.name; 196 nattr->attr.mode = 0444; 197 nattr->size = info->sechdrs[i].sh_size; 198 nattr->private = (void *)info->sechdrs[i].sh_addr; 199 nattr->read = sysfs_bin_attr_simple_read; 200 ++nattr; 201 } 202 ++loaded; 203 } 204 205 notes_attrs->dir = kobject_create_and_add("notes", &mod->mkobj.kobj); 206 if (!notes_attrs->dir) { 207 ret = -ENOMEM; 208 goto out; 209 } 210 211 for (i = 0; i < notes; ++i) { 212 ret = sysfs_create_bin_file(notes_attrs->dir, ¬es_attrs->attrs[i]); 213 if (ret) 214 goto out; 215 } 216 217 mod->notes_attrs = notes_attrs; 218 return 0; 219 220 out: 221 free_notes_attrs(notes_attrs, i); 222 return ret; 223 } 224 225 static void remove_notes_attrs(struct module *mod) 226 { 227 if (mod->notes_attrs) 228 free_notes_attrs(mod->notes_attrs, mod->notes_attrs->notes); 229 } 230 231 #else /* !CONFIG_KALLSYMS */ 232 static inline int add_sect_attrs(struct module *mod, const struct load_info *info) 233 { 234 return 0; 235 } 236 static inline void remove_sect_attrs(struct module *mod) { } 237 static inline int add_notes_attrs(struct module *mod, const struct load_info *info) 238 { 239 return 0; 240 } 241 static inline void remove_notes_attrs(struct module *mod) { } 242 #endif /* CONFIG_KALLSYMS */ 243 244 static void del_usage_links(struct module *mod) 245 { 246 #ifdef CONFIG_MODULE_UNLOAD 247 struct module_use *use; 248 249 mutex_lock(&module_mutex); 250 list_for_each_entry(use, &mod->target_list, target_list) 251 sysfs_remove_link(use->target->holders_dir, mod->name); 252 mutex_unlock(&module_mutex); 253 #endif 254 } 255 256 static int add_usage_links(struct module *mod) 257 { 258 int ret = 0; 259 #ifdef CONFIG_MODULE_UNLOAD 260 struct module_use *use; 261 262 mutex_lock(&module_mutex); 263 list_for_each_entry(use, &mod->target_list, target_list) { 264 ret = sysfs_create_link(use->target->holders_dir, 265 &mod->mkobj.kobj, mod->name); 266 if (ret) 267 break; 268 } 269 mutex_unlock(&module_mutex); 270 if (ret) 271 del_usage_links(mod); 272 #endif 273 return ret; 274 } 275 276 static void module_remove_modinfo_attrs(struct module *mod, int end) 277 { 278 struct module_attribute *attr; 279 int i; 280 281 for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) { 282 if (end >= 0 && i > end) 283 break; 284 /* pick a field to test for end of list */ 285 if (!attr->attr.name) 286 break; 287 sysfs_remove_file(&mod->mkobj.kobj, &attr->attr); 288 if (attr->free) 289 attr->free(mod); 290 } 291 kfree(mod->modinfo_attrs); 292 } 293 294 static int module_add_modinfo_attrs(struct module *mod) 295 { 296 struct module_attribute *attr; 297 struct module_attribute *temp_attr; 298 int error = 0; 299 int i; 300 301 mod->modinfo_attrs = kzalloc((sizeof(struct module_attribute) * 302 (modinfo_attrs_count + 1)), 303 GFP_KERNEL); 304 if (!mod->modinfo_attrs) 305 return -ENOMEM; 306 307 temp_attr = mod->modinfo_attrs; 308 for (i = 0; (attr = modinfo_attrs[i]); i++) { 309 if (!attr->test || attr->test(mod)) { 310 memcpy(temp_attr, attr, sizeof(*temp_attr)); 311 sysfs_attr_init(&temp_attr->attr); 312 error = sysfs_create_file(&mod->mkobj.kobj, 313 &temp_attr->attr); 314 if (error) 315 goto error_out; 316 ++temp_attr; 317 } 318 } 319 320 return 0; 321 322 error_out: 323 if (i > 0) 324 module_remove_modinfo_attrs(mod, --i); 325 else 326 kfree(mod->modinfo_attrs); 327 return error; 328 } 329 330 static void mod_kobject_put(struct module *mod) 331 { 332 DECLARE_COMPLETION_ONSTACK(c); 333 334 mod->mkobj.kobj_completion = &c; 335 kobject_put(&mod->mkobj.kobj); 336 wait_for_completion(&c); 337 } 338 339 static int mod_sysfs_init(struct module *mod) 340 { 341 int err; 342 struct kobject *kobj; 343 344 if (!module_kset) { 345 pr_err("%s: module sysfs not initialized\n", mod->name); 346 err = -EINVAL; 347 goto out; 348 } 349 350 kobj = kset_find_obj(module_kset, mod->name); 351 if (kobj) { 352 pr_err("%s: module is already loaded\n", mod->name); 353 kobject_put(kobj); 354 err = -EINVAL; 355 goto out; 356 } 357 358 mod->mkobj.mod = mod; 359 360 memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj)); 361 mod->mkobj.kobj.kset = module_kset; 362 err = kobject_init_and_add(&mod->mkobj.kobj, &module_ktype, NULL, 363 "%s", mod->name); 364 if (err) 365 mod_kobject_put(mod); 366 367 out: 368 return err; 369 } 370 371 int mod_sysfs_setup(struct module *mod, 372 const struct load_info *info, 373 struct kernel_param *kparam, 374 unsigned int num_params) 375 { 376 int err; 377 378 err = mod_sysfs_init(mod); 379 if (err) 380 goto out; 381 382 mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj); 383 if (!mod->holders_dir) { 384 err = -ENOMEM; 385 goto out_unreg; 386 } 387 388 err = module_param_sysfs_setup(mod, kparam, num_params); 389 if (err) 390 goto out_unreg_holders; 391 392 err = module_add_modinfo_attrs(mod); 393 if (err) 394 goto out_unreg_param; 395 396 err = add_usage_links(mod); 397 if (err) 398 goto out_unreg_modinfo_attrs; 399 400 err = add_sect_attrs(mod, info); 401 if (err) 402 goto out_del_usage_links; 403 404 err = add_notes_attrs(mod, info); 405 if (err) 406 goto out_unreg_sect_attrs; 407 408 return 0; 409 410 out_unreg_sect_attrs: 411 remove_sect_attrs(mod); 412 out_del_usage_links: 413 del_usage_links(mod); 414 out_unreg_modinfo_attrs: 415 module_remove_modinfo_attrs(mod, -1); 416 out_unreg_param: 417 module_param_sysfs_remove(mod); 418 out_unreg_holders: 419 kobject_put(mod->holders_dir); 420 out_unreg: 421 mod_kobject_put(mod); 422 out: 423 return err; 424 } 425 426 static void mod_sysfs_fini(struct module *mod) 427 { 428 remove_notes_attrs(mod); 429 remove_sect_attrs(mod); 430 mod_kobject_put(mod); 431 } 432 433 void mod_sysfs_teardown(struct module *mod) 434 { 435 del_usage_links(mod); 436 module_remove_modinfo_attrs(mod, -1); 437 module_param_sysfs_remove(mod); 438 kobject_put(mod->mkobj.drivers_dir); 439 kobject_put(mod->holders_dir); 440 mod_sysfs_fini(mod); 441 } 442 443 void init_param_lock(struct module *mod) 444 { 445 mutex_init(&mod->param_lock); 446 } 447