xref: /linux/kernel/params.c (revision 06d07429858317ded2db7986113a9e0129cd599b)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Helpers for initial module or kernel cmdline parsing
4  * Copyright (C) 2001 Rusty Russell.
5  */
6 #include <linux/ctype.h>
7 #include <linux/device.h>
8 #include <linux/err.h>
9 #include <linux/errno.h>
10 #include <linux/kernel.h>
11 #include <linux/kstrtox.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/overflow.h>
15 #include <linux/security.h>
16 #include <linux/slab.h>
17 #include <linux/string.h>
18 
19 #ifdef CONFIG_SYSFS
20 /* Protects all built-in parameters, modules use their own param_lock */
21 static DEFINE_MUTEX(param_lock);
22 
23 /* Use the module's mutex, or if built-in use the built-in mutex */
24 #ifdef CONFIG_MODULES
25 #define KPARAM_MUTEX(mod)	((mod) ? &(mod)->param_lock : &param_lock)
26 #else
27 #define KPARAM_MUTEX(mod)	(&param_lock)
28 #endif
29 
check_kparam_locked(struct module * mod)30 static inline void check_kparam_locked(struct module *mod)
31 {
32 	BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
33 }
34 #else
check_kparam_locked(struct module * mod)35 static inline void check_kparam_locked(struct module *mod)
36 {
37 }
38 #endif /* !CONFIG_SYSFS */
39 
40 /* This just allows us to keep track of which parameters are kmalloced. */
41 struct kmalloced_param {
42 	struct list_head list;
43 	char val[];
44 };
45 static LIST_HEAD(kmalloced_params);
46 static DEFINE_SPINLOCK(kmalloced_params_lock);
47 
kmalloc_parameter(unsigned int size)48 static void *kmalloc_parameter(unsigned int size)
49 {
50 	struct kmalloced_param *p;
51 
52 	p = kmalloc(size_add(sizeof(*p), size), GFP_KERNEL);
53 	if (!p)
54 		return NULL;
55 
56 	spin_lock(&kmalloced_params_lock);
57 	list_add(&p->list, &kmalloced_params);
58 	spin_unlock(&kmalloced_params_lock);
59 
60 	return p->val;
61 }
62 
63 /* Does nothing if parameter wasn't kmalloced above. */
maybe_kfree_parameter(void * param)64 static void maybe_kfree_parameter(void *param)
65 {
66 	struct kmalloced_param *p;
67 
68 	spin_lock(&kmalloced_params_lock);
69 	list_for_each_entry(p, &kmalloced_params, list) {
70 		if (p->val == param) {
71 			list_del(&p->list);
72 			kfree(p);
73 			break;
74 		}
75 	}
76 	spin_unlock(&kmalloced_params_lock);
77 }
78 
dash2underscore(char c)79 static char dash2underscore(char c)
80 {
81 	if (c == '-')
82 		return '_';
83 	return c;
84 }
85 
parameqn(const char * a,const char * b,size_t n)86 bool parameqn(const char *a, const char *b, size_t n)
87 {
88 	size_t i;
89 
90 	for (i = 0; i < n; i++) {
91 		if (dash2underscore(a[i]) != dash2underscore(b[i]))
92 			return false;
93 	}
94 	return true;
95 }
96 
parameq(const char * a,const char * b)97 bool parameq(const char *a, const char *b)
98 {
99 	return parameqn(a, b, strlen(a)+1);
100 }
101 
param_check_unsafe(const struct kernel_param * kp)102 static bool param_check_unsafe(const struct kernel_param *kp)
103 {
104 	if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
105 	    security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
106 		return false;
107 
108 	if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
109 		pr_notice("Setting dangerous option %s - tainting kernel\n",
110 			  kp->name);
111 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
112 	}
113 
114 	return true;
115 }
116 
parse_one(char * param,char * val,const char * doing,const struct kernel_param * params,unsigned num_params,s16 min_level,s16 max_level,void * arg,parse_unknown_fn handle_unknown)117 static int parse_one(char *param,
118 		     char *val,
119 		     const char *doing,
120 		     const struct kernel_param *params,
121 		     unsigned num_params,
122 		     s16 min_level,
123 		     s16 max_level,
124 		     void *arg, parse_unknown_fn handle_unknown)
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". */
parse_args(const char * doing,char * args,const struct kernel_param * params,unsigned num,s16 min_level,s16 max_level,void * arg,parse_unknown_fn unknown)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, parse_unknown_fn unknown)
168 {
169 	char *param, *val, *err = NULL;
170 
171 	/* Chew leading spaces */
172 	args = skip_spaces(args);
173 
174 	if (*args)
175 		pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);
176 
177 	while (*args) {
178 		int ret;
179 		int irq_was_disabled;
180 
181 		args = next_arg(args, &param, &val);
182 		/* Stop at -- */
183 		if (!val && strcmp(param, "--") == 0)
184 			return err ?: args;
185 		irq_was_disabled = irqs_disabled();
186 		ret = parse_one(param, val, doing, params, num,
187 				min_level, max_level, arg, unknown);
188 		if (irq_was_disabled && !irqs_disabled())
189 			pr_warn("%s: option '%s' enabled irq's!\n",
190 				doing, param);
191 
192 		switch (ret) {
193 		case 0:
194 			continue;
195 		case -ENOENT:
196 			pr_err("%s: Unknown parameter `%s'\n", doing, param);
197 			break;
198 		case -ENOSPC:
199 			pr_err("%s: `%s' too large for parameter `%s'\n",
200 			       doing, val ?: "", param);
201 			break;
202 		default:
203 			pr_err("%s: `%s' invalid for parameter `%s'\n",
204 			       doing, val ?: "", param);
205 			break;
206 		}
207 
208 		err = ERR_PTR(ret);
209 	}
210 
211 	return err;
212 }
213 
214 /* Lazy bastard, eh? */
215 #define STANDARD_PARAM_DEF(name, type, format, strtolfn)      		\
216 	int param_set_##name(const char *val, const struct kernel_param *kp) \
217 	{								\
218 		return strtolfn(val, 0, (type *)kp->arg);		\
219 	}								\
220 	int param_get_##name(char *buffer, const struct kernel_param *kp) \
221 	{								\
222 		return scnprintf(buffer, PAGE_SIZE, format "\n",	\
223 				*((type *)kp->arg));			\
224 	}								\
225 	const struct kernel_param_ops param_ops_##name = {			\
226 		.set = param_set_##name,				\
227 		.get = param_get_##name,				\
228 	};								\
229 	EXPORT_SYMBOL(param_set_##name);				\
230 	EXPORT_SYMBOL(param_get_##name);				\
231 	EXPORT_SYMBOL(param_ops_##name)
232 
233 
234 STANDARD_PARAM_DEF(byte,	unsigned char,		"%hhu",		kstrtou8);
235 STANDARD_PARAM_DEF(short,	short,			"%hi",		kstrtos16);
236 STANDARD_PARAM_DEF(ushort,	unsigned short,		"%hu",		kstrtou16);
237 STANDARD_PARAM_DEF(int,		int,			"%i",		kstrtoint);
238 STANDARD_PARAM_DEF(uint,	unsigned int,		"%u",		kstrtouint);
239 STANDARD_PARAM_DEF(long,	long,			"%li",		kstrtol);
240 STANDARD_PARAM_DEF(ulong,	unsigned long,		"%lu",		kstrtoul);
241 STANDARD_PARAM_DEF(ullong,	unsigned long long,	"%llu",		kstrtoull);
242 STANDARD_PARAM_DEF(hexint,	unsigned int,		"%#08x", 	kstrtouint);
243 
param_set_uint_minmax(const char * val,const struct kernel_param * kp,unsigned int min,unsigned int max)244 int param_set_uint_minmax(const char *val, const struct kernel_param *kp,
245 		unsigned int min, unsigned int max)
246 {
247 	unsigned int num;
248 	int ret;
249 
250 	if (!val)
251 		return -EINVAL;
252 	ret = kstrtouint(val, 0, &num);
253 	if (ret)
254 		return ret;
255 	if (num < min || num > max)
256 		return -EINVAL;
257 	*((unsigned int *)kp->arg) = num;
258 	return 0;
259 }
260 EXPORT_SYMBOL_GPL(param_set_uint_minmax);
261 
param_set_charp(const char * val,const struct kernel_param * kp)262 int param_set_charp(const char *val, const struct kernel_param *kp)
263 {
264 	size_t len, maxlen = 1024;
265 
266 	len = strnlen(val, maxlen + 1);
267 	if (len == maxlen + 1) {
268 		pr_err("%s: string parameter too long\n", kp->name);
269 		return -ENOSPC;
270 	}
271 
272 	maybe_kfree_parameter(*(char **)kp->arg);
273 
274 	/*
275 	 * This is a hack. We can't kmalloc() in early boot, and we
276 	 * don't need to; this mangled commandline is preserved.
277 	 */
278 	if (slab_is_available()) {
279 		*(char **)kp->arg = kmalloc_parameter(len + 1);
280 		if (!*(char **)kp->arg)
281 			return -ENOMEM;
282 		strcpy(*(char **)kp->arg, val);
283 	} else
284 		*(const char **)kp->arg = val;
285 
286 	return 0;
287 }
288 EXPORT_SYMBOL(param_set_charp);
289 
param_get_charp(char * buffer,const struct kernel_param * kp)290 int param_get_charp(char *buffer, const struct kernel_param *kp)
291 {
292 	return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
293 }
294 EXPORT_SYMBOL(param_get_charp);
295 
param_free_charp(void * arg)296 void param_free_charp(void *arg)
297 {
298 	maybe_kfree_parameter(*((char **)arg));
299 }
300 EXPORT_SYMBOL(param_free_charp);
301 
302 const struct kernel_param_ops param_ops_charp = {
303 	.set = param_set_charp,
304 	.get = param_get_charp,
305 	.free = param_free_charp,
306 };
307 EXPORT_SYMBOL(param_ops_charp);
308 
309 /* Actually could be a bool or an int, for historical reasons. */
param_set_bool(const char * val,const struct kernel_param * kp)310 int param_set_bool(const char *val, const struct kernel_param *kp)
311 {
312 	/* No equals means "set"... */
313 	if (!val) val = "1";
314 
315 	/* One of =[yYnN01] */
316 	return kstrtobool(val, kp->arg);
317 }
318 EXPORT_SYMBOL(param_set_bool);
319 
param_get_bool(char * buffer,const struct kernel_param * kp)320 int param_get_bool(char *buffer, const struct kernel_param *kp)
321 {
322 	/* Y and N chosen as being relatively non-coder friendly */
323 	return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
324 }
325 EXPORT_SYMBOL(param_get_bool);
326 
327 const struct kernel_param_ops param_ops_bool = {
328 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
329 	.set = param_set_bool,
330 	.get = param_get_bool,
331 };
332 EXPORT_SYMBOL(param_ops_bool);
333 
param_set_bool_enable_only(const char * val,const struct kernel_param * kp)334 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
335 {
336 	int err;
337 	bool new_value;
338 	bool orig_value = *(bool *)kp->arg;
339 	struct kernel_param dummy_kp = *kp;
340 
341 	dummy_kp.arg = &new_value;
342 
343 	err = param_set_bool(val, &dummy_kp);
344 	if (err)
345 		return err;
346 
347 	/* Don't let them unset it once it's set! */
348 	if (!new_value && orig_value)
349 		return -EROFS;
350 
351 	if (new_value)
352 		err = param_set_bool(val, kp);
353 
354 	return err;
355 }
356 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
357 
358 const struct kernel_param_ops param_ops_bool_enable_only = {
359 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
360 	.set = param_set_bool_enable_only,
361 	.get = param_get_bool,
362 };
363 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
364 
365 /* This one must be bool. */
param_set_invbool(const char * val,const struct kernel_param * kp)366 int param_set_invbool(const char *val, const struct kernel_param *kp)
367 {
368 	int ret;
369 	bool boolval;
370 	struct kernel_param dummy;
371 
372 	dummy.arg = &boolval;
373 	ret = param_set_bool(val, &dummy);
374 	if (ret == 0)
375 		*(bool *)kp->arg = !boolval;
376 	return ret;
377 }
378 EXPORT_SYMBOL(param_set_invbool);
379 
param_get_invbool(char * buffer,const struct kernel_param * kp)380 int param_get_invbool(char *buffer, const struct kernel_param *kp)
381 {
382 	return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
383 }
384 EXPORT_SYMBOL(param_get_invbool);
385 
386 const struct kernel_param_ops param_ops_invbool = {
387 	.set = param_set_invbool,
388 	.get = param_get_invbool,
389 };
390 EXPORT_SYMBOL(param_ops_invbool);
391 
param_set_bint(const char * val,const struct kernel_param * kp)392 int param_set_bint(const char *val, const struct kernel_param *kp)
393 {
394 	/* Match bool exactly, by re-using it. */
395 	struct kernel_param boolkp = *kp;
396 	bool v;
397 	int ret;
398 
399 	boolkp.arg = &v;
400 
401 	ret = param_set_bool(val, &boolkp);
402 	if (ret == 0)
403 		*(int *)kp->arg = v;
404 	return ret;
405 }
406 EXPORT_SYMBOL(param_set_bint);
407 
408 const struct kernel_param_ops param_ops_bint = {
409 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
410 	.set = param_set_bint,
411 	.get = param_get_int,
412 };
413 EXPORT_SYMBOL(param_ops_bint);
414 
415 /* We break the rule and mangle the string. */
param_array(struct module * mod,const char * name,const char * val,unsigned int min,unsigned int max,void * elem,int elemsize,int (* set)(const char *,const struct kernel_param * kp),s16 level,unsigned int * num)416 static int param_array(struct module *mod,
417 		       const char *name,
418 		       const char *val,
419 		       unsigned int min, unsigned int max,
420 		       void *elem, int elemsize,
421 		       int (*set)(const char *, const struct kernel_param *kp),
422 		       s16 level,
423 		       unsigned int *num)
424 {
425 	int ret;
426 	struct kernel_param kp;
427 	char save;
428 
429 	/* Get the name right for errors. */
430 	kp.name = name;
431 	kp.arg = elem;
432 	kp.level = level;
433 
434 	*num = 0;
435 	/* We expect a comma-separated list of values. */
436 	do {
437 		int len;
438 
439 		if (*num == max) {
440 			pr_err("%s: can only take %i arguments\n", name, max);
441 			return -EINVAL;
442 		}
443 		len = strcspn(val, ",");
444 
445 		/* nul-terminate and parse */
446 		save = val[len];
447 		((char *)val)[len] = '\0';
448 		check_kparam_locked(mod);
449 		ret = set(val, &kp);
450 
451 		if (ret != 0)
452 			return ret;
453 		kp.arg += elemsize;
454 		val += len+1;
455 		(*num)++;
456 	} while (save == ',');
457 
458 	if (*num < min) {
459 		pr_err("%s: needs at least %i arguments\n", name, min);
460 		return -EINVAL;
461 	}
462 	return 0;
463 }
464 
param_array_set(const char * val,const struct kernel_param * kp)465 static int param_array_set(const char *val, const struct kernel_param *kp)
466 {
467 	const struct kparam_array *arr = kp->arr;
468 	unsigned int temp_num;
469 
470 	return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
471 			   arr->elemsize, arr->ops->set, kp->level,
472 			   arr->num ?: &temp_num);
473 }
474 
param_array_get(char * buffer,const struct kernel_param * kp)475 static int param_array_get(char *buffer, const struct kernel_param *kp)
476 {
477 	int i, off, ret;
478 	const struct kparam_array *arr = kp->arr;
479 	struct kernel_param p = *kp;
480 
481 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
482 		/* Replace \n with comma */
483 		if (i)
484 			buffer[off - 1] = ',';
485 		p.arg = arr->elem + arr->elemsize * i;
486 		check_kparam_locked(p.mod);
487 		ret = arr->ops->get(buffer + off, &p);
488 		if (ret < 0)
489 			return ret;
490 		off += ret;
491 	}
492 	buffer[off] = '\0';
493 	return off;
494 }
495 
param_array_free(void * arg)496 static void param_array_free(void *arg)
497 {
498 	unsigned int i;
499 	const struct kparam_array *arr = arg;
500 
501 	if (arr->ops->free)
502 		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
503 			arr->ops->free(arr->elem + arr->elemsize * i);
504 }
505 
506 const struct kernel_param_ops param_array_ops = {
507 	.set = param_array_set,
508 	.get = param_array_get,
509 	.free = param_array_free,
510 };
511 EXPORT_SYMBOL(param_array_ops);
512 
param_set_copystring(const char * val,const struct kernel_param * kp)513 int param_set_copystring(const char *val, const struct kernel_param *kp)
514 {
515 	const struct kparam_string *kps = kp->str;
516 
517 	if (strnlen(val, kps->maxlen) == kps->maxlen) {
518 		pr_err("%s: string doesn't fit in %u chars.\n",
519 		       kp->name, kps->maxlen-1);
520 		return -ENOSPC;
521 	}
522 	strcpy(kps->string, val);
523 	return 0;
524 }
525 EXPORT_SYMBOL(param_set_copystring);
526 
param_get_string(char * buffer,const struct kernel_param * kp)527 int param_get_string(char *buffer, const struct kernel_param *kp)
528 {
529 	const struct kparam_string *kps = kp->str;
530 	return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
531 }
532 EXPORT_SYMBOL(param_get_string);
533 
534 const struct kernel_param_ops param_ops_string = {
535 	.set = param_set_copystring,
536 	.get = param_get_string,
537 };
538 EXPORT_SYMBOL(param_ops_string);
539 
540 /* sysfs output in /sys/modules/XYZ/parameters/ */
541 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
542 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
543 
544 struct param_attribute
545 {
546 	struct module_attribute mattr;
547 	const struct kernel_param *param;
548 };
549 
550 struct module_param_attrs
551 {
552 	unsigned int num;
553 	struct attribute_group grp;
554 	struct param_attribute attrs[];
555 };
556 
557 #ifdef CONFIG_SYSFS
558 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
559 
param_attr_show(struct module_attribute * mattr,struct module_kobject * mk,char * buf)560 static ssize_t param_attr_show(struct module_attribute *mattr,
561 			       struct module_kobject *mk, char *buf)
562 {
563 	int count;
564 	struct param_attribute *attribute = to_param_attr(mattr);
565 
566 	if (!attribute->param->ops->get)
567 		return -EPERM;
568 
569 	kernel_param_lock(mk->mod);
570 	count = attribute->param->ops->get(buf, attribute->param);
571 	kernel_param_unlock(mk->mod);
572 	return count;
573 }
574 
575 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
param_attr_store(struct module_attribute * mattr,struct module_kobject * mk,const char * buf,size_t len)576 static ssize_t param_attr_store(struct module_attribute *mattr,
577 				struct module_kobject *mk,
578 				const char *buf, size_t len)
579 {
580  	int err;
581 	struct param_attribute *attribute = to_param_attr(mattr);
582 
583 	if (!attribute->param->ops->set)
584 		return -EPERM;
585 
586 	kernel_param_lock(mk->mod);
587 	if (param_check_unsafe(attribute->param))
588 		err = attribute->param->ops->set(buf, attribute->param);
589 	else
590 		err = -EPERM;
591 	kernel_param_unlock(mk->mod);
592 	if (!err)
593 		return len;
594 	return err;
595 }
596 #endif
597 
598 #ifdef CONFIG_MODULES
599 #define __modinit
600 #else
601 #define __modinit __init
602 #endif
603 
604 #ifdef CONFIG_SYSFS
kernel_param_lock(struct module * mod)605 void kernel_param_lock(struct module *mod)
606 {
607 	mutex_lock(KPARAM_MUTEX(mod));
608 }
609 
kernel_param_unlock(struct module * mod)610 void kernel_param_unlock(struct module *mod)
611 {
612 	mutex_unlock(KPARAM_MUTEX(mod));
613 }
614 
615 EXPORT_SYMBOL(kernel_param_lock);
616 EXPORT_SYMBOL(kernel_param_unlock);
617 
618 /*
619  * add_sysfs_param - add a parameter to sysfs
620  * @mk: struct module_kobject
621  * @kp: the actual parameter definition to add to sysfs
622  * @name: name of parameter
623  *
624  * Create a kobject if for a (per-module) parameter if mp NULL, and
625  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
626  * if there's an error.
627  */
add_sysfs_param(struct module_kobject * mk,const struct kernel_param * kp,const char * name)628 static __modinit int add_sysfs_param(struct module_kobject *mk,
629 				     const struct kernel_param *kp,
630 				     const char *name)
631 {
632 	struct module_param_attrs *new_mp;
633 	struct attribute **new_attrs;
634 	unsigned int i;
635 
636 	/* We don't bother calling this with invisible parameters. */
637 	BUG_ON(!kp->perm);
638 
639 	if (!mk->mp) {
640 		/* First allocation. */
641 		mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
642 		if (!mk->mp)
643 			return -ENOMEM;
644 		mk->mp->grp.name = "parameters";
645 		/* NULL-terminated attribute array. */
646 		mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
647 					    GFP_KERNEL);
648 		/* Caller will cleanup via free_module_param_attrs */
649 		if (!mk->mp->grp.attrs)
650 			return -ENOMEM;
651 	}
652 
653 	/* Enlarge allocations. */
654 	new_mp = krealloc(mk->mp,
655 			  sizeof(*mk->mp) +
656 			  sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
657 			  GFP_KERNEL);
658 	if (!new_mp)
659 		return -ENOMEM;
660 	mk->mp = new_mp;
661 
662 	/* Extra pointer for NULL terminator */
663 	new_attrs = krealloc(mk->mp->grp.attrs,
664 			     sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
665 			     GFP_KERNEL);
666 	if (!new_attrs)
667 		return -ENOMEM;
668 	mk->mp->grp.attrs = new_attrs;
669 
670 	/* Tack new one on the end. */
671 	memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
672 	sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
673 	mk->mp->attrs[mk->mp->num].param = kp;
674 	mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
675 	/* Do not allow runtime DAC changes to make param writable. */
676 	if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
677 		mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
678 	else
679 		mk->mp->attrs[mk->mp->num].mattr.store = NULL;
680 	mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
681 	mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
682 	mk->mp->num++;
683 
684 	/* Fix up all the pointers, since krealloc can move us */
685 	for (i = 0; i < mk->mp->num; i++)
686 		mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
687 	mk->mp->grp.attrs[mk->mp->num] = NULL;
688 	return 0;
689 }
690 
691 #ifdef CONFIG_MODULES
free_module_param_attrs(struct module_kobject * mk)692 static void free_module_param_attrs(struct module_kobject *mk)
693 {
694 	if (mk->mp)
695 		kfree(mk->mp->grp.attrs);
696 	kfree(mk->mp);
697 	mk->mp = NULL;
698 }
699 
700 /*
701  * module_param_sysfs_setup - setup sysfs support for one module
702  * @mod: module
703  * @kparam: module parameters (array)
704  * @num_params: number of module parameters
705  *
706  * Adds sysfs entries for module parameters under
707  * /sys/module/[mod->name]/parameters/
708  */
module_param_sysfs_setup(struct module * mod,const struct kernel_param * kparam,unsigned int num_params)709 int module_param_sysfs_setup(struct module *mod,
710 			     const struct kernel_param *kparam,
711 			     unsigned int num_params)
712 {
713 	int i, err;
714 	bool params = false;
715 
716 	for (i = 0; i < num_params; i++) {
717 		if (kparam[i].perm == 0)
718 			continue;
719 		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
720 		if (err) {
721 			free_module_param_attrs(&mod->mkobj);
722 			return err;
723 		}
724 		params = true;
725 	}
726 
727 	if (!params)
728 		return 0;
729 
730 	/* Create the param group. */
731 	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
732 	if (err)
733 		free_module_param_attrs(&mod->mkobj);
734 	return err;
735 }
736 
737 /*
738  * module_param_sysfs_remove - remove sysfs support for one module
739  * @mod: module
740  *
741  * Remove sysfs entries for module parameters and the corresponding
742  * kobject.
743  */
module_param_sysfs_remove(struct module * mod)744 void module_param_sysfs_remove(struct module *mod)
745 {
746 	if (mod->mkobj.mp) {
747 		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
748 		/*
749 		 * We are positive that no one is using any param
750 		 * attrs at this point. Deallocate immediately.
751 		 */
752 		free_module_param_attrs(&mod->mkobj);
753 	}
754 }
755 #endif
756 
destroy_params(const struct kernel_param * params,unsigned num)757 void destroy_params(const struct kernel_param *params, unsigned num)
758 {
759 	unsigned int i;
760 
761 	for (i = 0; i < num; i++)
762 		if (params[i].ops->free)
763 			params[i].ops->free(params[i].arg);
764 }
765 
locate_module_kobject(const char * name)766 static struct module_kobject * __init locate_module_kobject(const char *name)
767 {
768 	struct module_kobject *mk;
769 	struct kobject *kobj;
770 	int err;
771 
772 	kobj = kset_find_obj(module_kset, name);
773 	if (kobj) {
774 		mk = to_module_kobject(kobj);
775 	} else {
776 		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
777 		BUG_ON(!mk);
778 
779 		mk->mod = THIS_MODULE;
780 		mk->kobj.kset = module_kset;
781 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
782 					   "%s", name);
783 #ifdef CONFIG_MODULES
784 		if (!err)
785 			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
786 #endif
787 		if (err) {
788 			kobject_put(&mk->kobj);
789 			pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
790 				name, err);
791 			return NULL;
792 		}
793 
794 		/* So that we hold reference in both cases. */
795 		kobject_get(&mk->kobj);
796 	}
797 
798 	return mk;
799 }
800 
kernel_add_sysfs_param(const char * name,const struct kernel_param * kparam,unsigned int name_skip)801 static void __init kernel_add_sysfs_param(const char *name,
802 					  const struct kernel_param *kparam,
803 					  unsigned int name_skip)
804 {
805 	struct module_kobject *mk;
806 	int err;
807 
808 	mk = locate_module_kobject(name);
809 	if (!mk)
810 		return;
811 
812 	/* We need to remove old parameters before adding more. */
813 	if (mk->mp)
814 		sysfs_remove_group(&mk->kobj, &mk->mp->grp);
815 
816 	/* These should not fail at boot. */
817 	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
818 	BUG_ON(err);
819 	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
820 	BUG_ON(err);
821 	kobject_uevent(&mk->kobj, KOBJ_ADD);
822 	kobject_put(&mk->kobj);
823 }
824 
825 /*
826  * param_sysfs_builtin - add sysfs parameters for built-in modules
827  *
828  * Add module_parameters to sysfs for "modules" built into the kernel.
829  *
830  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
831  * "parameter" name is stored behind a dot in kernel_param->name. So,
832  * extract the "module" name for all built-in kernel_param-eters,
833  * and for all who have the same, call kernel_add_sysfs_param.
834  */
param_sysfs_builtin(void)835 static void __init param_sysfs_builtin(void)
836 {
837 	const struct kernel_param *kp;
838 	unsigned int name_len;
839 	char modname[MODULE_NAME_LEN];
840 
841 	for (kp = __start___param; kp < __stop___param; kp++) {
842 		char *dot;
843 
844 		if (kp->perm == 0)
845 			continue;
846 
847 		dot = strchr(kp->name, '.');
848 		if (!dot) {
849 			/* This happens for core_param() */
850 			strcpy(modname, "kernel");
851 			name_len = 0;
852 		} else {
853 			name_len = dot - kp->name + 1;
854 			strscpy(modname, kp->name, name_len);
855 		}
856 		kernel_add_sysfs_param(modname, kp, name_len);
857 	}
858 }
859 
__modver_version_show(struct module_attribute * mattr,struct module_kobject * mk,char * buf)860 ssize_t __modver_version_show(struct module_attribute *mattr,
861 			      struct module_kobject *mk, char *buf)
862 {
863 	struct module_version_attribute *vattr =
864 		container_of(mattr, struct module_version_attribute, mattr);
865 
866 	return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
867 }
868 
869 extern const struct module_version_attribute __start___modver[];
870 extern const struct module_version_attribute __stop___modver[];
871 
version_sysfs_builtin(void)872 static void __init version_sysfs_builtin(void)
873 {
874 	const struct module_version_attribute *vattr;
875 	struct module_kobject *mk;
876 	int err;
877 
878 	for (vattr = __start___modver; vattr < __stop___modver; vattr++) {
879 		mk = locate_module_kobject(vattr->module_name);
880 		if (mk) {
881 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
882 			WARN_ON_ONCE(err);
883 			kobject_uevent(&mk->kobj, KOBJ_ADD);
884 			kobject_put(&mk->kobj);
885 		}
886 	}
887 }
888 
889 /* module-related sysfs stuff */
890 
module_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)891 static ssize_t module_attr_show(struct kobject *kobj,
892 				struct attribute *attr,
893 				char *buf)
894 {
895 	struct module_attribute *attribute;
896 	struct module_kobject *mk;
897 	int ret;
898 
899 	attribute = to_module_attr(attr);
900 	mk = to_module_kobject(kobj);
901 
902 	if (!attribute->show)
903 		return -EIO;
904 
905 	ret = attribute->show(attribute, mk, buf);
906 
907 	return ret;
908 }
909 
module_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t len)910 static ssize_t module_attr_store(struct kobject *kobj,
911 				struct attribute *attr,
912 				const char *buf, size_t len)
913 {
914 	struct module_attribute *attribute;
915 	struct module_kobject *mk;
916 	int ret;
917 
918 	attribute = to_module_attr(attr);
919 	mk = to_module_kobject(kobj);
920 
921 	if (!attribute->store)
922 		return -EIO;
923 
924 	ret = attribute->store(attribute, mk, buf, len);
925 
926 	return ret;
927 }
928 
929 static const struct sysfs_ops module_sysfs_ops = {
930 	.show = module_attr_show,
931 	.store = module_attr_store,
932 };
933 
uevent_filter(const struct kobject * kobj)934 static int uevent_filter(const struct kobject *kobj)
935 {
936 	const struct kobj_type *ktype = get_ktype(kobj);
937 
938 	if (ktype == &module_ktype)
939 		return 1;
940 	return 0;
941 }
942 
943 static const struct kset_uevent_ops module_uevent_ops = {
944 	.filter = uevent_filter,
945 };
946 
947 struct kset *module_kset;
948 
module_kobj_release(struct kobject * kobj)949 static void module_kobj_release(struct kobject *kobj)
950 {
951 	struct module_kobject *mk = to_module_kobject(kobj);
952 	complete(mk->kobj_completion);
953 }
954 
955 const struct kobj_type module_ktype = {
956 	.release   =	module_kobj_release,
957 	.sysfs_ops =	&module_sysfs_ops,
958 };
959 
960 /*
961  * param_sysfs_init - create "module" kset
962  *
963  * This must be done before the initramfs is unpacked and
964  * request_module() thus becomes possible, because otherwise the
965  * module load would fail in mod_sysfs_init.
966  */
param_sysfs_init(void)967 static int __init param_sysfs_init(void)
968 {
969 	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
970 	if (!module_kset) {
971 		printk(KERN_WARNING "%s (%d): error creating kset\n",
972 			__FILE__, __LINE__);
973 		return -ENOMEM;
974 	}
975 
976 	return 0;
977 }
978 subsys_initcall(param_sysfs_init);
979 
980 /*
981  * param_sysfs_builtin_init - add sysfs version and parameter
982  * attributes for built-in modules
983  */
param_sysfs_builtin_init(void)984 static int __init param_sysfs_builtin_init(void)
985 {
986 	if (!module_kset)
987 		return -ENOMEM;
988 
989 	version_sysfs_builtin();
990 	param_sysfs_builtin();
991 
992 	return 0;
993 }
994 late_initcall(param_sysfs_builtin_init);
995 
996 #endif /* CONFIG_SYSFS */
997