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 void free_notes_attrs(struct module_notes_attrs *notes_attrs, 150 unsigned int i) 151 { 152 if (notes_attrs->dir) { 153 while (i-- > 0) 154 sysfs_remove_bin_file(notes_attrs->dir, 155 ¬es_attrs->attrs[i]); 156 kobject_put(notes_attrs->dir); 157 } 158 kfree(notes_attrs); 159 } 160 161 static void add_notes_attrs(struct module *mod, const struct load_info *info) 162 { 163 unsigned int notes, loaded, i; 164 struct module_notes_attrs *notes_attrs; 165 struct bin_attribute *nattr; 166 167 /* failed to create section attributes, so can't create notes */ 168 if (!mod->sect_attrs) 169 return; 170 171 /* Count notes sections and allocate structures. */ 172 notes = 0; 173 for (i = 0; i < info->hdr->e_shnum; i++) 174 if (!sect_empty(&info->sechdrs[i]) && 175 info->sechdrs[i].sh_type == SHT_NOTE) 176 ++notes; 177 178 if (notes == 0) 179 return; 180 181 notes_attrs = kzalloc(struct_size(notes_attrs, attrs, notes), 182 GFP_KERNEL); 183 if (!notes_attrs) 184 return; 185 186 notes_attrs->notes = notes; 187 nattr = ¬es_attrs->attrs[0]; 188 for (loaded = i = 0; i < info->hdr->e_shnum; ++i) { 189 if (sect_empty(&info->sechdrs[i])) 190 continue; 191 if (info->sechdrs[i].sh_type == SHT_NOTE) { 192 sysfs_bin_attr_init(nattr); 193 nattr->attr.name = mod->sect_attrs->attrs[loaded].battr.attr.name; 194 nattr->attr.mode = 0444; 195 nattr->size = info->sechdrs[i].sh_size; 196 nattr->private = (void *)info->sechdrs[i].sh_addr; 197 nattr->read = sysfs_bin_attr_simple_read; 198 ++nattr; 199 } 200 ++loaded; 201 } 202 203 notes_attrs->dir = kobject_create_and_add("notes", &mod->mkobj.kobj); 204 if (!notes_attrs->dir) 205 goto out; 206 207 for (i = 0; i < notes; ++i) 208 if (sysfs_create_bin_file(notes_attrs->dir, 209 ¬es_attrs->attrs[i])) 210 goto out; 211 212 mod->notes_attrs = notes_attrs; 213 return; 214 215 out: 216 free_notes_attrs(notes_attrs, i); 217 } 218 219 static void remove_notes_attrs(struct module *mod) 220 { 221 if (mod->notes_attrs) 222 free_notes_attrs(mod->notes_attrs, mod->notes_attrs->notes); 223 } 224 225 #else /* !CONFIG_KALLSYMS */ 226 static inline void add_sect_attrs(struct module *mod, const struct load_info *info) { } 227 static inline void remove_sect_attrs(struct module *mod) { } 228 static inline void add_notes_attrs(struct module *mod, const struct load_info *info) { } 229 static inline void remove_notes_attrs(struct module *mod) { } 230 #endif /* CONFIG_KALLSYMS */ 231 232 static void del_usage_links(struct module *mod) 233 { 234 #ifdef CONFIG_MODULE_UNLOAD 235 struct module_use *use; 236 237 mutex_lock(&module_mutex); 238 list_for_each_entry(use, &mod->target_list, target_list) 239 sysfs_remove_link(use->target->holders_dir, mod->name); 240 mutex_unlock(&module_mutex); 241 #endif 242 } 243 244 static int add_usage_links(struct module *mod) 245 { 246 int ret = 0; 247 #ifdef CONFIG_MODULE_UNLOAD 248 struct module_use *use; 249 250 mutex_lock(&module_mutex); 251 list_for_each_entry(use, &mod->target_list, target_list) { 252 ret = sysfs_create_link(use->target->holders_dir, 253 &mod->mkobj.kobj, mod->name); 254 if (ret) 255 break; 256 } 257 mutex_unlock(&module_mutex); 258 if (ret) 259 del_usage_links(mod); 260 #endif 261 return ret; 262 } 263 264 static void module_remove_modinfo_attrs(struct module *mod, int end) 265 { 266 struct module_attribute *attr; 267 int i; 268 269 for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) { 270 if (end >= 0 && i > end) 271 break; 272 /* pick a field to test for end of list */ 273 if (!attr->attr.name) 274 break; 275 sysfs_remove_file(&mod->mkobj.kobj, &attr->attr); 276 if (attr->free) 277 attr->free(mod); 278 } 279 kfree(mod->modinfo_attrs); 280 } 281 282 static int module_add_modinfo_attrs(struct module *mod) 283 { 284 struct module_attribute *attr; 285 struct module_attribute *temp_attr; 286 int error = 0; 287 int i; 288 289 mod->modinfo_attrs = kzalloc((sizeof(struct module_attribute) * 290 (modinfo_attrs_count + 1)), 291 GFP_KERNEL); 292 if (!mod->modinfo_attrs) 293 return -ENOMEM; 294 295 temp_attr = mod->modinfo_attrs; 296 for (i = 0; (attr = modinfo_attrs[i]); i++) { 297 if (!attr->test || attr->test(mod)) { 298 memcpy(temp_attr, attr, sizeof(*temp_attr)); 299 sysfs_attr_init(&temp_attr->attr); 300 error = sysfs_create_file(&mod->mkobj.kobj, 301 &temp_attr->attr); 302 if (error) 303 goto error_out; 304 ++temp_attr; 305 } 306 } 307 308 return 0; 309 310 error_out: 311 if (i > 0) 312 module_remove_modinfo_attrs(mod, --i); 313 else 314 kfree(mod->modinfo_attrs); 315 return error; 316 } 317 318 static void mod_kobject_put(struct module *mod) 319 { 320 DECLARE_COMPLETION_ONSTACK(c); 321 322 mod->mkobj.kobj_completion = &c; 323 kobject_put(&mod->mkobj.kobj); 324 wait_for_completion(&c); 325 } 326 327 static int mod_sysfs_init(struct module *mod) 328 { 329 int err; 330 struct kobject *kobj; 331 332 if (!module_kset) { 333 pr_err("%s: module sysfs not initialized\n", mod->name); 334 err = -EINVAL; 335 goto out; 336 } 337 338 kobj = kset_find_obj(module_kset, mod->name); 339 if (kobj) { 340 pr_err("%s: module is already loaded\n", mod->name); 341 kobject_put(kobj); 342 err = -EINVAL; 343 goto out; 344 } 345 346 mod->mkobj.mod = mod; 347 348 memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj)); 349 mod->mkobj.kobj.kset = module_kset; 350 err = kobject_init_and_add(&mod->mkobj.kobj, &module_ktype, NULL, 351 "%s", mod->name); 352 if (err) 353 mod_kobject_put(mod); 354 355 out: 356 return err; 357 } 358 359 int mod_sysfs_setup(struct module *mod, 360 const struct load_info *info, 361 struct kernel_param *kparam, 362 unsigned int num_params) 363 { 364 int err; 365 366 err = mod_sysfs_init(mod); 367 if (err) 368 goto out; 369 370 mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj); 371 if (!mod->holders_dir) { 372 err = -ENOMEM; 373 goto out_unreg; 374 } 375 376 err = module_param_sysfs_setup(mod, kparam, num_params); 377 if (err) 378 goto out_unreg_holders; 379 380 err = module_add_modinfo_attrs(mod); 381 if (err) 382 goto out_unreg_param; 383 384 err = add_usage_links(mod); 385 if (err) 386 goto out_unreg_modinfo_attrs; 387 388 add_sect_attrs(mod, info); 389 add_notes_attrs(mod, info); 390 391 return 0; 392 393 out_unreg_modinfo_attrs: 394 module_remove_modinfo_attrs(mod, -1); 395 out_unreg_param: 396 module_param_sysfs_remove(mod); 397 out_unreg_holders: 398 kobject_put(mod->holders_dir); 399 out_unreg: 400 mod_kobject_put(mod); 401 out: 402 return err; 403 } 404 405 static void mod_sysfs_fini(struct module *mod) 406 { 407 remove_notes_attrs(mod); 408 remove_sect_attrs(mod); 409 mod_kobject_put(mod); 410 } 411 412 void mod_sysfs_teardown(struct module *mod) 413 { 414 del_usage_links(mod); 415 module_remove_modinfo_attrs(mod, -1); 416 module_param_sysfs_remove(mod); 417 kobject_put(mod->mkobj.drivers_dir); 418 kobject_put(mod->holders_dir); 419 mod_sysfs_fini(mod); 420 } 421 422 void init_param_lock(struct module *mod) 423 { 424 mutex_init(&mod->param_lock); 425 } 426