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; 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(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; 342 343 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(&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 } 437