xref: /openbmc/linux/kernel/params.c (revision ed84ef1c)
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_uint_minmax(const char *val, const struct kernel_param *kp,
247 		unsigned int min, unsigned int max)
248 {
249 	unsigned int num;
250 	int ret;
251 
252 	if (!val)
253 		return -EINVAL;
254 	ret = kstrtouint(val, 0, &num);
255 	if (ret)
256 		return ret;
257 	if (num < min || num > max)
258 		return -EINVAL;
259 	*((unsigned int *)kp->arg) = num;
260 	return 0;
261 }
262 EXPORT_SYMBOL_GPL(param_set_uint_minmax);
263 
264 int param_set_charp(const char *val, const struct kernel_param *kp)
265 {
266 	if (strlen(val) > 1024) {
267 		pr_err("%s: string parameter too long\n", kp->name);
268 		return -ENOSPC;
269 	}
270 
271 	maybe_kfree_parameter(*(char **)kp->arg);
272 
273 	/* This is a hack.  We can't kmalloc in early boot, and we
274 	 * don't need to; this mangled commandline is preserved. */
275 	if (slab_is_available()) {
276 		*(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
277 		if (!*(char **)kp->arg)
278 			return -ENOMEM;
279 		strcpy(*(char **)kp->arg, val);
280 	} else
281 		*(const char **)kp->arg = val;
282 
283 	return 0;
284 }
285 EXPORT_SYMBOL(param_set_charp);
286 
287 int param_get_charp(char *buffer, const struct kernel_param *kp)
288 {
289 	return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
290 }
291 EXPORT_SYMBOL(param_get_charp);
292 
293 void param_free_charp(void *arg)
294 {
295 	maybe_kfree_parameter(*((char **)arg));
296 }
297 EXPORT_SYMBOL(param_free_charp);
298 
299 const struct kernel_param_ops param_ops_charp = {
300 	.set = param_set_charp,
301 	.get = param_get_charp,
302 	.free = param_free_charp,
303 };
304 EXPORT_SYMBOL(param_ops_charp);
305 
306 /* Actually could be a bool or an int, for historical reasons. */
307 int param_set_bool(const char *val, const struct kernel_param *kp)
308 {
309 	/* No equals means "set"... */
310 	if (!val) val = "1";
311 
312 	/* One of =[yYnN01] */
313 	return strtobool(val, kp->arg);
314 }
315 EXPORT_SYMBOL(param_set_bool);
316 
317 int param_get_bool(char *buffer, const struct kernel_param *kp)
318 {
319 	/* Y and N chosen as being relatively non-coder friendly */
320 	return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
321 }
322 EXPORT_SYMBOL(param_get_bool);
323 
324 const struct kernel_param_ops param_ops_bool = {
325 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
326 	.set = param_set_bool,
327 	.get = param_get_bool,
328 };
329 EXPORT_SYMBOL(param_ops_bool);
330 
331 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
332 {
333 	int err = 0;
334 	bool new_value;
335 	bool orig_value = *(bool *)kp->arg;
336 	struct kernel_param dummy_kp = *kp;
337 
338 	dummy_kp.arg = &new_value;
339 
340 	err = param_set_bool(val, &dummy_kp);
341 	if (err)
342 		return err;
343 
344 	/* Don't let them unset it once it's set! */
345 	if (!new_value && orig_value)
346 		return -EROFS;
347 
348 	if (new_value)
349 		err = param_set_bool(val, kp);
350 
351 	return err;
352 }
353 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
354 
355 const struct kernel_param_ops param_ops_bool_enable_only = {
356 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
357 	.set = param_set_bool_enable_only,
358 	.get = param_get_bool,
359 };
360 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
361 
362 /* This one must be bool. */
363 int param_set_invbool(const char *val, const struct kernel_param *kp)
364 {
365 	int ret;
366 	bool boolval;
367 	struct kernel_param dummy;
368 
369 	dummy.arg = &boolval;
370 	ret = param_set_bool(val, &dummy);
371 	if (ret == 0)
372 		*(bool *)kp->arg = !boolval;
373 	return ret;
374 }
375 EXPORT_SYMBOL(param_set_invbool);
376 
377 int param_get_invbool(char *buffer, const struct kernel_param *kp)
378 {
379 	return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
380 }
381 EXPORT_SYMBOL(param_get_invbool);
382 
383 const struct kernel_param_ops param_ops_invbool = {
384 	.set = param_set_invbool,
385 	.get = param_get_invbool,
386 };
387 EXPORT_SYMBOL(param_ops_invbool);
388 
389 int param_set_bint(const char *val, const struct kernel_param *kp)
390 {
391 	/* Match bool exactly, by re-using it. */
392 	struct kernel_param boolkp = *kp;
393 	bool v;
394 	int ret;
395 
396 	boolkp.arg = &v;
397 
398 	ret = param_set_bool(val, &boolkp);
399 	if (ret == 0)
400 		*(int *)kp->arg = v;
401 	return ret;
402 }
403 EXPORT_SYMBOL(param_set_bint);
404 
405 const struct kernel_param_ops param_ops_bint = {
406 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
407 	.set = param_set_bint,
408 	.get = param_get_int,
409 };
410 EXPORT_SYMBOL(param_ops_bint);
411 
412 /* We break the rule and mangle the string. */
413 static int param_array(struct module *mod,
414 		       const char *name,
415 		       const char *val,
416 		       unsigned int min, unsigned int max,
417 		       void *elem, int elemsize,
418 		       int (*set)(const char *, const struct kernel_param *kp),
419 		       s16 level,
420 		       unsigned int *num)
421 {
422 	int ret;
423 	struct kernel_param kp;
424 	char save;
425 
426 	/* Get the name right for errors. */
427 	kp.name = name;
428 	kp.arg = elem;
429 	kp.level = level;
430 
431 	*num = 0;
432 	/* We expect a comma-separated list of values. */
433 	do {
434 		int len;
435 
436 		if (*num == max) {
437 			pr_err("%s: can only take %i arguments\n", name, max);
438 			return -EINVAL;
439 		}
440 		len = strcspn(val, ",");
441 
442 		/* nul-terminate and parse */
443 		save = val[len];
444 		((char *)val)[len] = '\0';
445 		check_kparam_locked(mod);
446 		ret = set(val, &kp);
447 
448 		if (ret != 0)
449 			return ret;
450 		kp.arg += elemsize;
451 		val += len+1;
452 		(*num)++;
453 	} while (save == ',');
454 
455 	if (*num < min) {
456 		pr_err("%s: needs at least %i arguments\n", name, min);
457 		return -EINVAL;
458 	}
459 	return 0;
460 }
461 
462 static int param_array_set(const char *val, const struct kernel_param *kp)
463 {
464 	const struct kparam_array *arr = kp->arr;
465 	unsigned int temp_num;
466 
467 	return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
468 			   arr->elemsize, arr->ops->set, kp->level,
469 			   arr->num ?: &temp_num);
470 }
471 
472 static int param_array_get(char *buffer, const struct kernel_param *kp)
473 {
474 	int i, off, ret;
475 	const struct kparam_array *arr = kp->arr;
476 	struct kernel_param p = *kp;
477 
478 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
479 		/* Replace \n with comma */
480 		if (i)
481 			buffer[off - 1] = ',';
482 		p.arg = arr->elem + arr->elemsize * i;
483 		check_kparam_locked(p.mod);
484 		ret = arr->ops->get(buffer + off, &p);
485 		if (ret < 0)
486 			return ret;
487 		off += ret;
488 	}
489 	buffer[off] = '\0';
490 	return off;
491 }
492 
493 static void param_array_free(void *arg)
494 {
495 	unsigned int i;
496 	const struct kparam_array *arr = arg;
497 
498 	if (arr->ops->free)
499 		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
500 			arr->ops->free(arr->elem + arr->elemsize * i);
501 }
502 
503 const struct kernel_param_ops param_array_ops = {
504 	.set = param_array_set,
505 	.get = param_array_get,
506 	.free = param_array_free,
507 };
508 EXPORT_SYMBOL(param_array_ops);
509 
510 int param_set_copystring(const char *val, const struct kernel_param *kp)
511 {
512 	const struct kparam_string *kps = kp->str;
513 
514 	if (strlen(val)+1 > kps->maxlen) {
515 		pr_err("%s: string doesn't fit in %u chars.\n",
516 		       kp->name, kps->maxlen-1);
517 		return -ENOSPC;
518 	}
519 	strcpy(kps->string, val);
520 	return 0;
521 }
522 EXPORT_SYMBOL(param_set_copystring);
523 
524 int param_get_string(char *buffer, const struct kernel_param *kp)
525 {
526 	const struct kparam_string *kps = kp->str;
527 	return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
528 }
529 EXPORT_SYMBOL(param_get_string);
530 
531 const struct kernel_param_ops param_ops_string = {
532 	.set = param_set_copystring,
533 	.get = param_get_string,
534 };
535 EXPORT_SYMBOL(param_ops_string);
536 
537 /* sysfs output in /sys/modules/XYZ/parameters/ */
538 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
539 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
540 
541 struct param_attribute
542 {
543 	struct module_attribute mattr;
544 	const struct kernel_param *param;
545 };
546 
547 struct module_param_attrs
548 {
549 	unsigned int num;
550 	struct attribute_group grp;
551 	struct param_attribute attrs[];
552 };
553 
554 #ifdef CONFIG_SYSFS
555 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
556 
557 static ssize_t param_attr_show(struct module_attribute *mattr,
558 			       struct module_kobject *mk, char *buf)
559 {
560 	int count;
561 	struct param_attribute *attribute = to_param_attr(mattr);
562 
563 	if (!attribute->param->ops->get)
564 		return -EPERM;
565 
566 	kernel_param_lock(mk->mod);
567 	count = attribute->param->ops->get(buf, attribute->param);
568 	kernel_param_unlock(mk->mod);
569 	return count;
570 }
571 
572 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
573 static ssize_t param_attr_store(struct module_attribute *mattr,
574 				struct module_kobject *mk,
575 				const char *buf, size_t len)
576 {
577  	int err;
578 	struct param_attribute *attribute = to_param_attr(mattr);
579 
580 	if (!attribute->param->ops->set)
581 		return -EPERM;
582 
583 	kernel_param_lock(mk->mod);
584 	if (param_check_unsafe(attribute->param))
585 		err = attribute->param->ops->set(buf, attribute->param);
586 	else
587 		err = -EPERM;
588 	kernel_param_unlock(mk->mod);
589 	if (!err)
590 		return len;
591 	return err;
592 }
593 #endif
594 
595 #ifdef CONFIG_MODULES
596 #define __modinit
597 #else
598 #define __modinit __init
599 #endif
600 
601 #ifdef CONFIG_SYSFS
602 void kernel_param_lock(struct module *mod)
603 {
604 	mutex_lock(KPARAM_MUTEX(mod));
605 }
606 
607 void kernel_param_unlock(struct module *mod)
608 {
609 	mutex_unlock(KPARAM_MUTEX(mod));
610 }
611 
612 EXPORT_SYMBOL(kernel_param_lock);
613 EXPORT_SYMBOL(kernel_param_unlock);
614 
615 /*
616  * add_sysfs_param - add a parameter to sysfs
617  * @mk: struct module_kobject
618  * @kp: the actual parameter definition to add to sysfs
619  * @name: name of parameter
620  *
621  * Create a kobject if for a (per-module) parameter if mp NULL, and
622  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
623  * if there's an error.
624  */
625 static __modinit int add_sysfs_param(struct module_kobject *mk,
626 				     const struct kernel_param *kp,
627 				     const char *name)
628 {
629 	struct module_param_attrs *new_mp;
630 	struct attribute **new_attrs;
631 	unsigned int i;
632 
633 	/* We don't bother calling this with invisible parameters. */
634 	BUG_ON(!kp->perm);
635 
636 	if (!mk->mp) {
637 		/* First allocation. */
638 		mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
639 		if (!mk->mp)
640 			return -ENOMEM;
641 		mk->mp->grp.name = "parameters";
642 		/* NULL-terminated attribute array. */
643 		mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
644 					    GFP_KERNEL);
645 		/* Caller will cleanup via free_module_param_attrs */
646 		if (!mk->mp->grp.attrs)
647 			return -ENOMEM;
648 	}
649 
650 	/* Enlarge allocations. */
651 	new_mp = krealloc(mk->mp,
652 			  sizeof(*mk->mp) +
653 			  sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
654 			  GFP_KERNEL);
655 	if (!new_mp)
656 		return -ENOMEM;
657 	mk->mp = new_mp;
658 
659 	/* Extra pointer for NULL terminator */
660 	new_attrs = krealloc(mk->mp->grp.attrs,
661 			     sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
662 			     GFP_KERNEL);
663 	if (!new_attrs)
664 		return -ENOMEM;
665 	mk->mp->grp.attrs = new_attrs;
666 
667 	/* Tack new one on the end. */
668 	memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
669 	sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
670 	mk->mp->attrs[mk->mp->num].param = kp;
671 	mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
672 	/* Do not allow runtime DAC changes to make param writable. */
673 	if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
674 		mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
675 	else
676 		mk->mp->attrs[mk->mp->num].mattr.store = NULL;
677 	mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
678 	mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
679 	mk->mp->num++;
680 
681 	/* Fix up all the pointers, since krealloc can move us */
682 	for (i = 0; i < mk->mp->num; i++)
683 		mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
684 	mk->mp->grp.attrs[mk->mp->num] = NULL;
685 	return 0;
686 }
687 
688 #ifdef CONFIG_MODULES
689 static void free_module_param_attrs(struct module_kobject *mk)
690 {
691 	if (mk->mp)
692 		kfree(mk->mp->grp.attrs);
693 	kfree(mk->mp);
694 	mk->mp = NULL;
695 }
696 
697 /*
698  * module_param_sysfs_setup - setup sysfs support for one module
699  * @mod: module
700  * @kparam: module parameters (array)
701  * @num_params: number of module parameters
702  *
703  * Adds sysfs entries for module parameters under
704  * /sys/module/[mod->name]/parameters/
705  */
706 int module_param_sysfs_setup(struct module *mod,
707 			     const struct kernel_param *kparam,
708 			     unsigned int num_params)
709 {
710 	int i, err;
711 	bool params = false;
712 
713 	for (i = 0; i < num_params; i++) {
714 		if (kparam[i].perm == 0)
715 			continue;
716 		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
717 		if (err) {
718 			free_module_param_attrs(&mod->mkobj);
719 			return err;
720 		}
721 		params = true;
722 	}
723 
724 	if (!params)
725 		return 0;
726 
727 	/* Create the param group. */
728 	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
729 	if (err)
730 		free_module_param_attrs(&mod->mkobj);
731 	return err;
732 }
733 
734 /*
735  * module_param_sysfs_remove - remove sysfs support for one module
736  * @mod: module
737  *
738  * Remove sysfs entries for module parameters and the corresponding
739  * kobject.
740  */
741 void module_param_sysfs_remove(struct module *mod)
742 {
743 	if (mod->mkobj.mp) {
744 		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
745 		/* We are positive that no one is using any param
746 		 * attrs at this point.  Deallocate immediately. */
747 		free_module_param_attrs(&mod->mkobj);
748 	}
749 }
750 #endif
751 
752 void destroy_params(const struct kernel_param *params, unsigned num)
753 {
754 	unsigned int i;
755 
756 	for (i = 0; i < num; i++)
757 		if (params[i].ops->free)
758 			params[i].ops->free(params[i].arg);
759 }
760 
761 static struct module_kobject * __init locate_module_kobject(const char *name)
762 {
763 	struct module_kobject *mk;
764 	struct kobject *kobj;
765 	int err;
766 
767 	kobj = kset_find_obj(module_kset, name);
768 	if (kobj) {
769 		mk = to_module_kobject(kobj);
770 	} else {
771 		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
772 		BUG_ON(!mk);
773 
774 		mk->mod = THIS_MODULE;
775 		mk->kobj.kset = module_kset;
776 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
777 					   "%s", name);
778 #ifdef CONFIG_MODULES
779 		if (!err)
780 			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
781 #endif
782 		if (err) {
783 			kobject_put(&mk->kobj);
784 			pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
785 				name, err);
786 			return NULL;
787 		}
788 
789 		/* So that we hold reference in both cases. */
790 		kobject_get(&mk->kobj);
791 	}
792 
793 	return mk;
794 }
795 
796 static void __init kernel_add_sysfs_param(const char *name,
797 					  const struct kernel_param *kparam,
798 					  unsigned int name_skip)
799 {
800 	struct module_kobject *mk;
801 	int err;
802 
803 	mk = locate_module_kobject(name);
804 	if (!mk)
805 		return;
806 
807 	/* We need to remove old parameters before adding more. */
808 	if (mk->mp)
809 		sysfs_remove_group(&mk->kobj, &mk->mp->grp);
810 
811 	/* These should not fail at boot. */
812 	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
813 	BUG_ON(err);
814 	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
815 	BUG_ON(err);
816 	kobject_uevent(&mk->kobj, KOBJ_ADD);
817 	kobject_put(&mk->kobj);
818 }
819 
820 /*
821  * param_sysfs_builtin - add sysfs parameters for built-in modules
822  *
823  * Add module_parameters to sysfs for "modules" built into the kernel.
824  *
825  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
826  * "parameter" name is stored behind a dot in kernel_param->name. So,
827  * extract the "module" name for all built-in kernel_param-eters,
828  * and for all who have the same, call kernel_add_sysfs_param.
829  */
830 static void __init param_sysfs_builtin(void)
831 {
832 	const struct kernel_param *kp;
833 	unsigned int name_len;
834 	char modname[MODULE_NAME_LEN];
835 
836 	for (kp = __start___param; kp < __stop___param; kp++) {
837 		char *dot;
838 
839 		if (kp->perm == 0)
840 			continue;
841 
842 		dot = strchr(kp->name, '.');
843 		if (!dot) {
844 			/* This happens for core_param() */
845 			strcpy(modname, "kernel");
846 			name_len = 0;
847 		} else {
848 			name_len = dot - kp->name + 1;
849 			strlcpy(modname, kp->name, name_len);
850 		}
851 		kernel_add_sysfs_param(modname, kp, name_len);
852 	}
853 }
854 
855 ssize_t __modver_version_show(struct module_attribute *mattr,
856 			      struct module_kobject *mk, char *buf)
857 {
858 	struct module_version_attribute *vattr =
859 		container_of(mattr, struct module_version_attribute, mattr);
860 
861 	return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
862 }
863 
864 extern const struct module_version_attribute __start___modver[];
865 extern const struct module_version_attribute __stop___modver[];
866 
867 static void __init version_sysfs_builtin(void)
868 {
869 	const struct module_version_attribute *vattr;
870 	struct module_kobject *mk;
871 	int err;
872 
873 	for (vattr = __start___modver; vattr < __stop___modver; vattr++) {
874 		mk = locate_module_kobject(vattr->module_name);
875 		if (mk) {
876 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
877 			WARN_ON_ONCE(err);
878 			kobject_uevent(&mk->kobj, KOBJ_ADD);
879 			kobject_put(&mk->kobj);
880 		}
881 	}
882 }
883 
884 /* module-related sysfs stuff */
885 
886 static ssize_t module_attr_show(struct kobject *kobj,
887 				struct attribute *attr,
888 				char *buf)
889 {
890 	struct module_attribute *attribute;
891 	struct module_kobject *mk;
892 	int ret;
893 
894 	attribute = to_module_attr(attr);
895 	mk = to_module_kobject(kobj);
896 
897 	if (!attribute->show)
898 		return -EIO;
899 
900 	ret = attribute->show(attribute, mk, buf);
901 
902 	return ret;
903 }
904 
905 static ssize_t module_attr_store(struct kobject *kobj,
906 				struct attribute *attr,
907 				const char *buf, size_t len)
908 {
909 	struct module_attribute *attribute;
910 	struct module_kobject *mk;
911 	int ret;
912 
913 	attribute = to_module_attr(attr);
914 	mk = to_module_kobject(kobj);
915 
916 	if (!attribute->store)
917 		return -EIO;
918 
919 	ret = attribute->store(attribute, mk, buf, len);
920 
921 	return ret;
922 }
923 
924 static const struct sysfs_ops module_sysfs_ops = {
925 	.show = module_attr_show,
926 	.store = module_attr_store,
927 };
928 
929 static int uevent_filter(struct kset *kset, struct kobject *kobj)
930 {
931 	struct kobj_type *ktype = get_ktype(kobj);
932 
933 	if (ktype == &module_ktype)
934 		return 1;
935 	return 0;
936 }
937 
938 static const struct kset_uevent_ops module_uevent_ops = {
939 	.filter = uevent_filter,
940 };
941 
942 struct kset *module_kset;
943 int module_sysfs_initialized;
944 
945 static void module_kobj_release(struct kobject *kobj)
946 {
947 	struct module_kobject *mk = to_module_kobject(kobj);
948 	complete(mk->kobj_completion);
949 }
950 
951 struct kobj_type module_ktype = {
952 	.release   =	module_kobj_release,
953 	.sysfs_ops =	&module_sysfs_ops,
954 };
955 
956 /*
957  * param_sysfs_init - wrapper for built-in params support
958  */
959 static int __init param_sysfs_init(void)
960 {
961 	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
962 	if (!module_kset) {
963 		printk(KERN_WARNING "%s (%d): error creating kset\n",
964 			__FILE__, __LINE__);
965 		return -ENOMEM;
966 	}
967 	module_sysfs_initialized = 1;
968 
969 	version_sysfs_builtin();
970 	param_sysfs_builtin();
971 
972 	return 0;
973 }
974 subsys_initcall(param_sysfs_init);
975 
976 #endif /* CONFIG_SYSFS */
977