xref: /openbmc/linux/kernel/params.c (revision 36fe4655)
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 */
959