kernel/params.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Helpers for initial module or kernel cmdline parsing
   3    Copyright (C) 2001 Rusty Russell.
   4
   5 */
   6 #include <linux/kernel.h>
   7 #include <linux/string.h>
   8 #include <linux/errno.h>
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/device.h>
  12 #include <linux/err.h>
  13 #include <linux/slab.h>
  14 #include <linux/ctype.h>
  15 #include <linux/security.h>
  16
  17 #ifdef CONFIG_SYSFS
  18 /* Protects all built-in parameters, modules use their own param_lock */
  19 static DEFINE_MUTEX(param_lock);
  20
  21 /* Use the module's mutex, or if built-in use the built-in mutex */
  22 #ifdef CONFIG_MODULES
  23 #define KPARAM_MUTEX(mod)       ((mod) ? &(mod)->param_lock : &param_lock)
  24 #else
  25 #define KPARAM_MUTEX(mod)       (&param_lock)
  26 #endif
  27
  28 static inline void check_kparam_locked(struct module *mod)
  29 {
  30         BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
  31 }
  32 #else
  33 static inline void check_kparam_locked(struct module *mod)
  34 {
  35 }
  36 #endif /* !CONFIG_SYSFS */
  37
  38 /* This just allows us to keep track of which parameters are kmalloced. */
  39 struct kmalloced_param {
  40         struct list_head list;
  41         char val[];
  42 };
  43 static LIST_HEAD(kmalloced_params);
  44 static DEFINE_SPINLOCK(kmalloced_params_lock);
  45
  46 static void *kmalloc_parameter(unsigned int size)
  47 {
  48         struct kmalloced_param *p;
  49
  50         p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
  51         if (!p)
  52                 return NULL;
  53
  54         spin_lock(&kmalloced_params_lock);
  55         list_add(&p->list, &kmalloced_params);
  56         spin_unlock(&kmalloced_params_lock);
  57
  58         return p->val;
  59 }
  60
  61 /* Does nothing if parameter wasn't kmalloced above. */
  62 static void maybe_kfree_parameter(void *param)
  63 {
  64         struct kmalloced_param *p;
  65
  66         spin_lock(&kmalloced_params_lock);
  67         list_for_each_entry(p, &kmalloced_params, list) {
  68                 if (p->val == param) {
  69                         list_del(&p->list);
  70                         kfree(p);
  71                         break;
  72                 }
  73         }
  74         spin_unlock(&kmalloced_params_lock);
  75 }
  76
  77 static char dash2underscore(char c)
  78 {
  79         if (c == '-')
  80                 return '_';
  81         return c;
  82 }
  83
  84 bool parameqn(const char *a, const char *b, size_t n)
  85 {
  86         size_t i;
  87
  88         for (i = 0; i < n; i++) {
  89                 if (dash2underscore(a[i]) != dash2underscore(b[i]))
  90                         return false;
  91         }
  92         return true;
  93 }
  94
  95 bool parameq(const char *a, const char *b)
  96 {
  97         return parameqn(a, b, strlen(a)+1);
  98 }
  99
 100 static bool param_check_unsafe(const struct kernel_param *kp)
 101 {
 102         if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
 103             security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
 104                 return false;
 105
 106         if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
 107                 pr_notice("Setting dangerous option %s - tainting kernel\n",
 108                           kp->name);
 109                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 110         }
 111
 112         return true;
 113 }
 114
 115 static int parse_one(char *param,
 116                      char *val,
 117                      const char *doing,
 118                      const struct kernel_param *params,
 119                      unsigned num_params,
 120                      s16 min_level,
 121                      s16 max_level,
 122                      void *arg,
 123                      int (*handle_unknown)(char *param, char *val,
 124                                      const char *doing, void *arg))
 125 {
 126         unsigned int i;
 127         int err;
 128
 129         /* Find parameter */
 130         for (i = 0; i < num_params; i++) {
 131                 if (parameq(param, params[i].name)) {
 132                         if (params[i].level < min_level
 133                             || params[i].level > max_level)
 134                                 return 0;
 135                         /* No one handled NULL, so do it here. */
 136                         if (!val &&
 137                             !(params[i].ops->flags & KERNEL_PARAM_OPS_FL_NOARG))
 138                                 return -EINVAL;
 139                         pr_debug("handling %s with %p\n", param,
 140                                 params[i].ops->set);
 141                         kernel_param_lock(params[i].mod);
 142                         if (param_check_unsafe(&params[i]))
 143                                 err = params[i].ops->set(val, &params[i]);
 144                         else
 145                                 err = -EPERM;
 146                         kernel_param_unlock(params[i].mod);
 147                         return err;
 148                 }
 149         }
 150
 151         if (handle_unknown) {
 152                 pr_debug("doing %s: %s='%s'\n", doing, param, val);
 153                 return handle_unknown(param, val, doing, arg);
 154         }
 155
 156         pr_debug("Unknown argument '%s'\n", param);
 157         return -ENOENT;
 158 }
 159
 160 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
 161 char *parse_args(const char *doing,
 162                  char *args,
 163                  const struct kernel_param *params,
 164                  unsigned num,
 165                  s16 min_level,
 166                  s16 max_level,
 167                  void *arg,
 168                  int (*unknown)(char *param, char *val,
 169                                 const char *doing, void *arg))
 170 {
 171         char *param, *val, *err = NULL;
 172
 173         /* Chew leading spaces */
 174         args = skip_spaces(args);
 175
 176         if (*args)
 177                 pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);
 178
 179         while (*args) {
 180                 int ret;
 181                 int irq_was_disabled;
 182
 183                 args = next_arg(args, &param, &val);
 184                 /* Stop at -- */
 185                 if (!val && strcmp(param, "--") == 0)
 186                         return err ?: args;
 187                 irq_was_disabled = irqs_disabled();
 188                 ret = parse_one(param, val, doing, params, num,
 189                                 min_level, max_level, arg, unknown);
 190                 if (irq_was_disabled && !irqs_disabled())
 191                         pr_warn("%s: option '%s' enabled irq's!\n",
 192                                 doing, param);
 193
 194                 switch (ret) {
 195                 case 0:
 196                         continue;
 197                 case -ENOENT:
 198                         pr_err("%s: Unknown parameter `%s'\n", doing, param);
 199                         break;
 200                 case -ENOSPC:
 201                         pr_err("%s: `%s' too large for parameter `%s'\n",
 202                                doing, val ?: "", param);
 203                         break;
 204                 default:
 205                         pr_err("%s: `%s' invalid for parameter `%s'\n",
 206                                doing, val ?: "", param);
 207                         break;
 208                 }
 209
 210                 err = ERR_PTR(ret);
 211         }
 212
 213         return err;
 214 }
 215
 216 /* Lazy bastard, eh? */
 217 #define STANDARD_PARAM_DEF(name, type, format, strtolfn)                \
 218         int param_set_##name(const char *val, const struct kernel_param *kp) \
 219         {                                                               \
 220                 return strtolfn(val, 0, (type *)kp->arg);               \
 221         }                                                               \
 222         int param_get_##name(char *buffer, const struct kernel_param *kp) \
 223         {                                                               \
 224                 return scnprintf(buffer, PAGE_SIZE, format "\n",        \
 225                                 *((type *)kp->arg));                    \
 226         }                                                               \
 227         const struct kernel_param_ops param_ops_##name = {                      \
 228                 .set = param_set_##name,                                \
 229                 .get = param_get_##name,                                \
 230         };                                                              \
 231         EXPORT_SYMBOL(param_set_##name);                                \
 232         EXPORT_SYMBOL(param_get_##name);                                \
 233         EXPORT_SYMBOL(param_ops_##name)
 234
 235
 236 STANDARD_PARAM_DEF(byte,        unsigned char,          "%hhu",         kstrtou8);
 237 STANDARD_PARAM_DEF(short,       short,                  "%hi",          kstrtos16);
 238 STANDARD_PARAM_DEF(ushort,      unsigned short,         "%hu",          kstrtou16);
 239 STANDARD_PARAM_DEF(int,         int,                    "%i",           kstrtoint);
 240 STANDARD_PARAM_DEF(uint,        unsigned int,           "%u",           kstrtouint);
 241 STANDARD_PARAM_DEF(long,        long,                   "%li",          kstrtol);
 242 STANDARD_PARAM_DEF(ulong,       unsigned long,          "%lu",          kstrtoul);
 243 STANDARD_PARAM_DEF(ullong,      unsigned long long,     "%llu",         kstrtoull);
 244 STANDARD_PARAM_DEF(hexint,      unsigned int,           "%#08x",        kstrtouint);
 245
 246 int param_set_charp(const char *val, const struct kernel_param *kp)
 247 {
 248         if (strlen(val) > 1024) {
 249                 pr_err("%s: string parameter too long\n", kp->name);
 250                 return -ENOSPC;
 251         }
 252
 253         maybe_kfree_parameter(*(char **)kp->arg);
 254
 255         /* This is a hack.  We can't kmalloc in early boot, and we
 256          * don't need to; this mangled commandline is preserved. */
 257         if (slab_is_available()) {
 258                 *(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
 259                 if (!*(char **)kp->arg)
 260                         return -ENOMEM;
 261                 strcpy(*(char **)kp->arg, val);
 262         } else
 263                 *(const char **)kp->arg = val;
 264
 265         return 0;
 266 }
 267 EXPORT_SYMBOL(param_set_charp);
 268
 269 int param_get_charp(char *buffer, const struct kernel_param *kp)
 270 {
 271         return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
 272 }
 273 EXPORT_SYMBOL(param_get_charp);
 274
 275 void param_free_charp(void *arg)
 276 {
 277         maybe_kfree_parameter(*((char **)arg));
 278 }
 279 EXPORT_SYMBOL(param_free_charp);
 280
 281 const struct kernel_param_ops param_ops_charp = {
 282         .set = param_set_charp,
 283         .get = param_get_charp,
 284         .free = param_free_charp,
 285 };
 286 EXPORT_SYMBOL(param_ops_charp);
 287
 288 /* Actually could be a bool or an int, for historical reasons. */
 289 int param_set_bool(const char *val, const struct kernel_param *kp)
 290 {
 291         /* No equals means "set"... */
 292         if (!val) val = "1";
 293
 294         /* One of =[yYnN01] */
 295         return strtobool(val, kp->arg);
 296 }
 297 EXPORT_SYMBOL(param_set_bool);
 298
 299 int param_get_bool(char *buffer, const struct kernel_param *kp)
 300 {
 301         /* Y and N chosen as being relatively non-coder friendly */
 302         return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
 303 }
 304 EXPORT_SYMBOL(param_get_bool);
 305
 306 const struct kernel_param_ops param_ops_bool = {
 307         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 308         .set = param_set_bool,
 309         .get = param_get_bool,
 310 };
 311 EXPORT_SYMBOL(param_ops_bool);
 312
 313 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
 314 {
 315         int err = 0;
 316         bool new_value;
 317         bool orig_value = *(bool *)kp->arg;
 318         struct kernel_param dummy_kp = *kp;
 319
 320         dummy_kp.arg = &new_value;
 321
 322         err = param_set_bool(val, &dummy_kp);
 323         if (err)
 324                 return err;
 325
 326         /* Don't let them unset it once it's set! */
 327         if (!new_value && orig_value)
 328                 return -EROFS;
 329
 330         if (new_value)
 331                 err = param_set_bool(val, kp);
 332
 333         return err;
 334 }
 335 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
 336
 337 const struct kernel_param_ops param_ops_bool_enable_only = {
 338         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 339         .set = param_set_bool_enable_only,
 340         .get = param_get_bool,
 341 };
 342 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
 343
 344 /* This one must be bool. */
 345 int param_set_invbool(const char *val, const struct kernel_param *kp)
 346 {
 347         int ret;
 348         bool boolval;
 349         struct kernel_param dummy;
 350
 351         dummy.arg = &boolval;
 352         ret = param_set_bool(val, &dummy);
 353         if (ret == 0)
 354                 *(bool *)kp->arg = !boolval;
 355         return ret;
 356 }
 357 EXPORT_SYMBOL(param_set_invbool);
 358
 359 int param_get_invbool(char *buffer, const struct kernel_param *kp)
 360 {
 361         return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
 362 }
 363 EXPORT_SYMBOL(param_get_invbool);
 364
 365 const struct kernel_param_ops param_ops_invbool = {
 366         .set = param_set_invbool,
 367         .get = param_get_invbool,
 368 };
 369 EXPORT_SYMBOL(param_ops_invbool);
 370
 371 int param_set_bint(const char *val, const struct kernel_param *kp)
 372 {
 373         /* Match bool exactly, by re-using it. */
 374         struct kernel_param boolkp = *kp;
 375         bool v;
 376         int ret;
 377
 378         boolkp.arg = &v;
 379
 380         ret = param_set_bool(val, &boolkp);
 381         if (ret == 0)
 382                 *(int *)kp->arg = v;
 383         return ret;
 384 }
 385 EXPORT_SYMBOL(param_set_bint);
 386
 387 const struct kernel_param_ops param_ops_bint = {
 388         .flags = KERNEL_PARAM_OPS_FL_NOARG,
 389         .set = param_set_bint,
 390         .get = param_get_int,
 391 };
 392 EXPORT_SYMBOL(param_ops_bint);
 393
 394 /* We break the rule and mangle the string. */
 395 static int param_array(struct module *mod,
 396                        const char *name,
 397                        const char *val,
 398                        unsigned int min, unsigned int max,
 399                        void *elem, int elemsize,
 400                        int (*set)(const char *, const struct kernel_param *kp),
 401                        s16 level,
 402                        unsigned int *num)
 403 {
 404         int ret;
 405         struct kernel_param kp;
 406         char save;
 407
 408         /* Get the name right for errors. */
 409         kp.name = name;
 410         kp.arg = elem;
 411         kp.level = level;
 412
 413         *num = 0;
 414         /* We expect a comma-separated list of values. */
 415         do {
 416                 int len;
 417
 418                 if (*num == max) {
 419                         pr_err("%s: can only take %i arguments\n", name, max);
 420                         return -EINVAL;
 421                 }
 422                 len = strcspn(val, ",");
 423
 424                 /* nul-terminate and parse */
 425                 save = val[len];
 426                 ((char *)val)[len] = '\0';
 427                 check_kparam_locked(mod);
 428                 ret = set(val, &kp);
 429
 430                 if (ret != 0)
 431                         return ret;
 432                 kp.arg += elemsize;
 433                 val += len+1;
 434                 (*num)++;
 435         } while (save == ',');
 436
 437         if (*num < min) {
 438                 pr_err("%s: needs at least %i arguments\n", name, min);
 439                 return -EINVAL;
 440         }
 441         return 0;
 442 }
 443
 444 static int param_array_set(const char *val, const struct kernel_param *kp)
 445 {
 446         const struct kparam_array *arr = kp->arr;
 447         unsigned int temp_num;
 448
 449         return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
 450                            arr->elemsize, arr->ops->set, kp->level,
 451                            arr->num ?: &temp_num);
 452 }
 453
 454 static int param_array_get(char *buffer, const struct kernel_param *kp)
 455 {
 456         int i, off, ret;
 457         const struct kparam_array *arr = kp->arr;
 458         struct kernel_param p = *kp;
 459
 460         for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 461                 /* Replace \n with comma */
 462                 if (i)
 463                         buffer[off - 1] = ',';
 464                 p.arg = arr->elem + arr->elemsize * i;
 465                 check_kparam_locked(p.mod);
 466                 ret = arr->ops->get(buffer + off, &p);
 467                 if (ret < 0)
 468                         return ret;
 469                 off += ret;
 470         }
 471         buffer[off] = '\0';
 472         return off;
 473 }
 474
 475 static void param_array_free(void *arg)
 476 {
 477         unsigned int i;
 478         const struct kparam_array *arr = arg;
 479
 480         if (arr->ops->free)
 481                 for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
 482                         arr->ops->free(arr->elem + arr->elemsize * i);
 483 }
 484
 485 const struct kernel_param_ops param_array_ops = {
 486         .set = param_array_set,
 487         .get = param_array_get,
 488         .free = param_array_free,
 489 };
 490 EXPORT_SYMBOL(param_array_ops);
 491
 492 int param_set_copystring(const char *val, const struct kernel_param *kp)
 493 {
 494         const struct kparam_string *kps = kp->str;
 495
 496         if (strlen(val)+1 > kps->maxlen) {
 497                 pr_err("%s: string doesn't fit in %u chars.\n",
 498                        kp->name, kps->maxlen-1);
 499                 return -ENOSPC;
 500         }
 501         strcpy(kps->string, val);
 502         return 0;
 503 }
 504 EXPORT_SYMBOL(param_set_copystring);
 505
 506 int param_get_string(char *buffer, const struct kernel_param *kp)
 507 {
 508         const struct kparam_string *kps = kp->str;
 509         return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
 510 }
 511 EXPORT_SYMBOL(param_get_string);
 512
 513 const struct kernel_param_ops param_ops_string = {
 514         .set = param_set_copystring,
 515         .get = param_get_string,
 516 };
 517 EXPORT_SYMBOL(param_ops_string);
 518
 519 /* sysfs output in /sys/modules/XYZ/parameters/ */
 520 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
 521 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
 522
 523 struct param_attribute
 524 {
 525         struct module_attribute mattr;
 526         const struct kernel_param *param;
 527 };
 528
 529 struct module_param_attrs
 530 {
 531         unsigned int num;
 532         struct attribute_group grp;
 533         struct param_attribute attrs[];
 534 };
 535
 536 #ifdef CONFIG_SYSFS
 537 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
 538
 539 static ssize_t param_attr_show(struct module_attribute *mattr,
 540                                struct module_kobject *mk, char *buf)
 541 {
 542         int count;
 543         struct param_attribute *attribute = to_param_attr(mattr);
 544
 545         if (!attribute->param->ops->get)
 546                 return -EPERM;
 547
 548         kernel_param_lock(mk->mod);
 549         count = attribute->param->ops->get(buf, attribute->param);
 550         kernel_param_unlock(mk->mod);
 551         return count;
 552 }
 553
 554 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 555 static ssize_t param_attr_store(struct module_attribute *mattr,
 556                                 struct module_kobject *mk,
 557                                 const char *buf, size_t len)
 558 {
 559         int err;
 560         struct param_attribute *attribute = to_param_attr(mattr);
 561
 562         if (!attribute->param->ops->set)
 563                 return -EPERM;
 564
 565         kernel_param_lock(mk->mod);
 566         if (param_check_unsafe(attribute->param))
 567                 err = attribute->param->ops->set(buf, attribute->param);
 568         else
 569                 err = -EPERM;
 570         kernel_param_unlock(mk->mod);
 571         if (!err)
 572                 return len;
 573         return err;
 574 }
 575 #endif
 576
 577 #ifdef CONFIG_MODULES
 578 #define __modinit
 579 #else
 580 #define __modinit __init
 581 #endif
 582
 583 #ifdef CONFIG_SYSFS
 584 void kernel_param_lock(struct module *mod)
 585 {
 586         mutex_lock(KPARAM_MUTEX(mod));
 587 }
 588
 589 void kernel_param_unlock(struct module *mod)
 590 {
 591         mutex_unlock(KPARAM_MUTEX(mod));
 592 }
 593
 594 EXPORT_SYMBOL(kernel_param_lock);
 595 EXPORT_SYMBOL(kernel_param_unlock);
 596
 597 /*
 598  * add_sysfs_param - add a parameter to sysfs
 599  * @mk: struct module_kobject
 600  * @kp: the actual parameter definition to add to sysfs
 601  * @name: name of parameter
 602  *
 603  * Create a kobject if for a (per-module) parameter if mp NULL, and
 604  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
 605  * if there's an error.
 606  */
 607 static __modinit int add_sysfs_param(struct module_kobject *mk,
 608                                      const struct kernel_param *kp,
 609                                      const char *name)
 610 {
 611         struct module_param_attrs *new_mp;
 612         struct attribute **new_attrs;
 613         unsigned int i;
 614
 615         /* We don't bother calling this with invisible parameters. */
 616         BUG_ON(!kp->perm);
 617
 618         if (!mk->mp) {
 619                 /* First allocation. */
 620                 mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
 621                 if (!mk->mp)
 622                         return -ENOMEM;
 623                 mk->mp->grp.name = "parameters";
 624                 /* NULL-terminated attribute array. */
 625                 mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
 626                                             GFP_KERNEL);
 627                 /* Caller will cleanup via free_module_param_attrs */
 628                 if (!mk->mp->grp.attrs)
 629                         return -ENOMEM;
 630         }
 631
 632         /* Enlarge allocations. */
 633         new_mp = krealloc(mk->mp,
 634                           sizeof(*mk->mp) +
 635                           sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
 636                           GFP_KERNEL);
 637         if (!new_mp)
 638                 return -ENOMEM;
 639         mk->mp = new_mp;
 640
 641         /* Extra pointer for NULL terminator */
 642         new_attrs = krealloc(mk->mp->grp.attrs,
 643                              sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
 644                              GFP_KERNEL);
 645         if (!new_attrs)
 646                 return -ENOMEM;
 647         mk->mp->grp.attrs = new_attrs;
 648
 649         /* Tack new one on the end. */
 650         memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
 651         sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
 652         mk->mp->attrs[mk->mp->num].param = kp;
 653         mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
 654         /* Do not allow runtime DAC changes to make param writable. */
 655         if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
 656                 mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
 657         else
 658                 mk->mp->attrs[mk->mp->num].mattr.store = NULL;
 659         mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
 660         mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
 661         mk->mp->num++;
 662
 663         /* Fix up all the pointers, since krealloc can move us */
 664         for (i = 0; i < mk->mp->num; i++)
 665                 mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
 666         mk->mp->grp.attrs[mk->mp->num] = NULL;
 667         return 0;
 668 }
 669
 670 #ifdef CONFIG_MODULES
 671 static void free_module_param_attrs(struct module_kobject *mk)
 672 {
 673         if (mk->mp)
 674                 kfree(mk->mp->grp.attrs);
 675         kfree(mk->mp);
 676         mk->mp = NULL;
 677 }
 678
 679 /*
 680  * module_param_sysfs_setup - setup sysfs support for one module
 681  * @mod: module
 682  * @kparam: module parameters (array)
 683  * @num_params: number of module parameters
 684  *
 685  * Adds sysfs entries for module parameters under
 686  * /sys/module/[mod->name]/parameters/
 687  */
 688 int module_param_sysfs_setup(struct module *mod,
 689                              const struct kernel_param *kparam,
 690                              unsigned int num_params)
 691 {
 692         int i, err;
 693         bool params = false;
 694
 695         for (i = 0; i < num_params; i++) {
 696                 if (kparam[i].perm == 0)
 697                         continue;
 698                 err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
 699                 if (err) {
 700                         free_module_param_attrs(&mod->mkobj);
 701                         return err;
 702                 }
 703                 params = true;
 704         }
 705
 706         if (!params)
 707                 return 0;
 708
 709         /* Create the param group. */
 710         err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 711         if (err)
 712                 free_module_param_attrs(&mod->mkobj);
 713         return err;
 714 }
 715
 716 /*
 717  * module_param_sysfs_remove - remove sysfs support for one module
 718  * @mod: module
 719  *
 720  * Remove sysfs entries for module parameters and the corresponding
 721  * kobject.
 722  */
 723 void module_param_sysfs_remove(struct module *mod)
 724 {
 725         if (mod->mkobj.mp) {
 726                 sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
 727                 /* We are positive that no one is using any param
 728                  * attrs at this point.  Deallocate immediately. */
 729                 free_module_param_attrs(&mod->mkobj);
 730         }
 731 }
 732 #endif
 733
 734 void destroy_params(const struct kernel_param *params, unsigned num)
 735 {
 736         unsigned int i;
 737
 738         for (i = 0; i < num; i++)
 739                 if (params[i].ops->free)
 740                         params[i].ops->free(params[i].arg);
 741 }
 742
 743 static struct module_kobject * __init locate_module_kobject(const char *name)
 744 {
 745         struct module_kobject *mk;
 746         struct kobject *kobj;
 747         int err;
 748
 749         kobj = kset_find_obj(module_kset, name);
 750         if (kobj) {
 751                 mk = to_module_kobject(kobj);
 752         } else {
 753                 mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
 754                 BUG_ON(!mk);
 755
 756                 mk->mod = THIS_MODULE;
 757                 mk->kobj.kset = module_kset;
 758                 err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
 759                                            "%s", name);
 760 #ifdef CONFIG_MODULES
 761                 if (!err)
 762                         err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
 763 #endif
 764                 if (err) {
 765                         kobject_put(&mk->kobj);
 766                         pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
 767                                 name, err);
 768                         return NULL;
 769                 }
 770
 771                 /* So that we hold reference in both cases. */
 772                 kobject_get(&mk->kobj);
 773         }
 774
 775         return mk;
 776 }
 777
 778 static void __init kernel_add_sysfs_param(const char *name,
 779                                           const struct kernel_param *kparam,
 780                                           unsigned int name_skip)
 781 {
 782         struct module_kobject *mk;
 783         int err;
 784
 785         mk = locate_module_kobject(name);
 786         if (!mk)
 787                 return;
 788
 789         /* We need to remove old parameters before adding more. */
 790         if (mk->mp)
 791                 sysfs_remove_group(&mk->kobj, &mk->mp->grp);
 792
 793         /* These should not fail at boot. */
 794         err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
 795         BUG_ON(err);
 796         err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
 797         BUG_ON(err);
 798         kobject_uevent(&mk->kobj, KOBJ_ADD);
 799         kobject_put(&mk->kobj);
 800 }
 801
 802 /*
 803  * param_sysfs_builtin - add sysfs parameters for built-in modules
 804  *
 805  * Add module_parameters to sysfs for "modules" built into the kernel.
 806  *
 807  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
 808  * "parameter" name is stored behind a dot in kernel_param->name. So,
 809  * extract the "module" name for all built-in kernel_param-eters,
 810  * and for all who have the same, call kernel_add_sysfs_param.
 811  */
 812 static void __init param_sysfs_builtin(void)
 813 {
 814         const struct kernel_param *kp;
 815         unsigned int name_len;
 816         char modname[MODULE_NAME_LEN];
 817
 818         for (kp = __start___param; kp < __stop___param; kp++) {
 819                 char *dot;
 820
 821                 if (kp->perm == 0)
 822                         continue;
 823
 824                 dot = strchr(kp->name, '.');
 825                 if (!dot) {
 826                         /* This happens for core_param() */
 827                         strcpy(modname, "kernel");
 828                         name_len = 0;
 829                 } else {
 830                         name_len = dot - kp->name + 1;
 831                         strlcpy(modname, kp->name, name_len);
 832                 }
 833                 kernel_add_sysfs_param(modname, kp, name_len);
 834         }
 835 }
 836
 837 ssize_t __modver_version_show(struct module_attribute *mattr,
 838                               struct module_kobject *mk, char *buf)
 839 {
 840         struct module_version_attribute *vattr =
 841                 container_of(mattr, struct module_version_attribute, mattr);
 842
 843         return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
 844 }
 845
 846 extern const struct module_version_attribute __start___modver[];
 847 extern const struct module_version_attribute __stop___modver[];
 848
 849 static void __init version_sysfs_builtin(void)
 850 {
 851         const struct module_version_attribute *vattr;
 852         struct module_kobject *mk;
 853         int err;
 854
 855         for (vattr = __start___modver; vattr < __stop___modver; vattr++) {
 856                 mk = locate_module_kobject(vattr->module_name);
 857                 if (mk) {
 858                         err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
 859                         WARN_ON_ONCE(err);
 860                         kobject_uevent(&mk->kobj, KOBJ_ADD);
 861                         kobject_put(&mk->kobj);
 862                 }
 863         }
 864 }
 865
 866 /* module-related sysfs stuff */
 867
 868 static ssize_t module_attr_show(struct kobject *kobj,
 869                                 struct attribute *attr,
 870                                 char *buf)
 871 {
 872         struct module_attribute *attribute;
 873         struct module_kobject *mk;
 874         int ret;
 875
 876         attribute = to_module_attr(attr);
 877         mk = to_module_kobject(kobj);
 878
 879         if (!attribute->show)
 880                 return -EIO;
 881
 882         ret = attribute->show(attribute, mk, buf);
 883
 884         return ret;
 885 }
 886
 887 static ssize_t module_attr_store(struct kobject *kobj,
 888                                 struct attribute *attr,
 889                                 const char *buf, size_t len)
 890 {
 891         struct module_attribute *attribute;
 892         struct module_kobject *mk;
 893         int ret;
 894
 895         attribute = to_module_attr(attr);
 896         mk = to_module_kobject(kobj);
 897
 898         if (!attribute->store)
 899                 return -EIO;
 900
 901         ret = attribute->store(attribute, mk, buf, len);
 902
 903         return ret;
 904 }
 905
 906 static const struct sysfs_ops module_sysfs_ops = {
 907         .show = module_attr_show,
 908         .store = module_attr_store,
 909 };
 910
 911 static int uevent_filter(struct kset *kset, struct kobject *kobj)
 912 {
 913         struct kobj_type *ktype = get_ktype(kobj);
 914
 915         if (ktype == &module_ktype)
 916                 return 1;
 917         return 0;
 918 }
 919
 920 static const struct kset_uevent_ops module_uevent_ops = {
 921         .filter = uevent_filter,
 922 };
 923
 924 struct kset *module_kset;
 925 int module_sysfs_initialized;
 926
 927 static void module_kobj_release(struct kobject *kobj)
 928 {
 929         struct module_kobject *mk = to_module_kobject(kobj);
 930         complete(mk->kobj_completion);
 931 }
 932
 933 struct kobj_type module_ktype = {
 934         .release   =    module_kobj_release,
 935         .sysfs_ops =    &module_sysfs_ops,
 936 };
 937
 938 /*
 939  * param_sysfs_init - wrapper for built-in params support
 940  */
 941 static int __init param_sysfs_init(void)
 942 {
 943         module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
 944         if (!module_kset) {
 945                 printk(KERN_WARNING "%s (%d): error creating kset\n",
 946                         __FILE__, __LINE__);
 947                 return -ENOMEM;
 948         }
 949         module_sysfs_initialized = 1;
 950
 951         version_sysfs_builtin();
 952         param_sysfs_builtin();
 953
 954         return 0;
 955 }
 956 subsys_initcall(param_sysfs_init);
 957
 958 #endif /* CONFIG_SYSFS */