xref: /openbmc/linux/kernel/params.c (revision 9ce170ce)
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/kstrtox.h>
8 #include <linux/string.h>
9 #include <linux/errno.h>
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/device.h>
13 #include <linux/err.h>
14 #include <linux/slab.h>
15 #include <linux/ctype.h>
16 #include <linux/security.h>
17 
18 #ifdef CONFIG_SYSFS
19 /* Protects all built-in parameters, modules use their own param_lock */
20 static DEFINE_MUTEX(param_lock);
21 
22 /* Use the module's mutex, or if built-in use the built-in mutex */
23 #ifdef CONFIG_MODULES
24 #define KPARAM_MUTEX(mod)	((mod) ? &(mod)->param_lock : &param_lock)
25 #else
26 #define KPARAM_MUTEX(mod)	(&param_lock)
27 #endif
28 
check_kparam_locked(struct module * mod)29 static inline void check_kparam_locked(struct module *mod)
30 {
31 	BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
32 }
33 #else
check_kparam_locked(struct module * mod)34 static inline void check_kparam_locked(struct module *mod)
35 {
36 }
37 #endif /* !CONFIG_SYSFS */
38 
39 /* This just allows us to keep track of which parameters are kmalloced. */
40 struct kmalloced_param {
41 	struct list_head list;
42 	char val[];
43 };
44 static LIST_HEAD(kmalloced_params);
45 static DEFINE_SPINLOCK(kmalloced_params_lock);
46 
kmalloc_parameter(unsigned int size)47 static void *kmalloc_parameter(unsigned int size)
48 {
49 	struct kmalloced_param *p;
50 
51 	p = kmalloc(sizeof(*p) + size, GFP_KERNEL);
52 	if (!p)
53 		return NULL;
54 
55 	spin_lock(&kmalloced_params_lock);
56 	list_add(&p->list, &kmalloced_params);
57 	spin_unlock(&kmalloced_params_lock);
58 
59 	return p->val;
60 }
61 
62 /* Does nothing if parameter wasn't kmalloced above. */
maybe_kfree_parameter(void * param)63 static void maybe_kfree_parameter(void *param)
64 {
65 	struct kmalloced_param *p;
66 
67 	spin_lock(&kmalloced_params_lock);
68 	list_for_each_entry(p, &kmalloced_params, list) {
69 		if (p->val == param) {
70 			list_del(&p->list);
71 			kfree(p);
72 			break;
73 		}
74 	}
75 	spin_unlock(&kmalloced_params_lock);
76 }
77 
dash2underscore(char c)78 static char dash2underscore(char c)
79 {
80 	if (c == '-')
81 		return '_';
82 	return c;
83 }
84 
parameqn(const char * a,const char * b,size_t n)85 bool parameqn(const char *a, const char *b, size_t n)
86 {
87 	size_t i;
88 
89 	for (i = 0; i < n; i++) {
90 		if (dash2underscore(a[i]) != dash2underscore(b[i]))
91 			return false;
92 	}
93 	return true;
94 }
95 
parameq(const char * a,const char * b)96 bool parameq(const char *a, const char *b)
97 {
98 	return parameqn(a, b, strlen(a)+1);
99 }
100 
param_check_unsafe(const struct kernel_param * kp)101 static bool param_check_unsafe(const struct kernel_param *kp)
102 {
103 	if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
104 	    security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
105 		return false;
106 
107 	if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
108 		pr_notice("Setting dangerous option %s - tainting kernel\n",
109 			  kp->name);
110 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
111 	}
112 
113 	return true;
114 }
115 
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,int (* handle_unknown)(char * param,char * val,const char * doing,void * arg))116 static int parse_one(char *param,
117 		     char *val,
118 		     const char *doing,
119 		     const struct kernel_param *params,
120 		     unsigned num_params,
121 		     s16 min_level,
122 		     s16 max_level,
123 		     void *arg,
124 		     int (*handle_unknown)(char *param, char *val,
125 				     const char *doing, void *arg))
126 {
127 	unsigned int i;
128 	int err;
129 
130 	/* Find parameter */
131 	for (i = 0; i < num_params; i++) {
132 		if (parameq(param, params[i].name)) {
133 			if (params[i].level < min_level
134 			    || params[i].level > max_level)
135 				return 0;
136 			/* No one handled NULL, so do it here. */
137 			if (!val &&
138 			    !(params[i].ops->flags & KERNEL_PARAM_OPS_FL_NOARG))
139 				return -EINVAL;
140 			pr_debug("handling %s with %p\n", param,
141 				params[i].ops->set);
142 			kernel_param_lock(params[i].mod);
143 			if (param_check_unsafe(&params[i]))
144 				err = params[i].ops->set(val, &params[i]);
145 			else
146 				err = -EPERM;
147 			kernel_param_unlock(params[i].mod);
148 			return err;
149 		}
150 	}
151 
152 	if (handle_unknown) {
153 		pr_debug("doing %s: %s='%s'\n", doing, param, val);
154 		return handle_unknown(param, val, doing, arg);
155 	}
156 
157 	pr_debug("Unknown argument '%s'\n", param);
158 	return -ENOENT;
159 }
160 
161 /* 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,int (* unknown)(char * param,char * val,const char * doing,void * arg))162 char *parse_args(const char *doing,
163 		 char *args,
164 		 const struct kernel_param *params,
165 		 unsigned num,
166 		 s16 min_level,
167 		 s16 max_level,
168 		 void *arg,
169 		 int (*unknown)(char *param, char *val,
170 				const char *doing, void *arg))
171 {
172 	char *param, *val, *err = NULL;
173 
174 	/* Chew leading spaces */
175 	args = skip_spaces(args);
176 
177 	if (*args)
178 		pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);
179 
180 	while (*args) {
181 		int ret;
182 		int irq_was_disabled;
183 
184 		args = next_arg(args, &param, &val);
185 		/* Stop at -- */
186 		if (!val && strcmp(param, "--") == 0)
187 			return err ?: args;
188 		irq_was_disabled = irqs_disabled();
189 		ret = parse_one(param, val, doing, params, num,
190 				min_level, max_level, arg, unknown);
191 		if (irq_was_disabled && !irqs_disabled())
192 			pr_warn("%s: option '%s' enabled irq's!\n",
193 				doing, param);
194 
195 		switch (ret) {
196 		case 0:
197 			continue;
198 		case -ENOENT:
199 			pr_err("%s: Unknown parameter `%s'\n", doing, param);
200 			break;
201 		case -ENOSPC:
202 			pr_err("%s: `%s' too large for parameter `%s'\n",
203 			       doing, val ?: "", param);
204 			break;
205 		default:
206 			pr_err("%s: `%s' invalid for parameter `%s'\n",
207 			       doing, val ?: "", param);
208 			break;
209 		}
210 
211 		err = ERR_PTR(ret);
212 	}
213 
214 	return err;
215 }
216 
217 /* Lazy bastard, eh? */
218 #define STANDARD_PARAM_DEF(name, type, format, strtolfn)      		\
219 	int param_set_##name(const char *val, const struct kernel_param *kp) \
220 	{								\
221 		return strtolfn(val, 0, (type *)kp->arg);		\
222 	}								\
223 	int param_get_##name(char *buffer, const struct kernel_param *kp) \
224 	{								\
225 		return scnprintf(buffer, PAGE_SIZE, format "\n",	\
226 				*((type *)kp->arg));			\
227 	}								\
228 	const struct kernel_param_ops param_ops_##name = {			\
229 		.set = param_set_##name,				\
230 		.get = param_get_##name,				\
231 	};								\
232 	EXPORT_SYMBOL(param_set_##name);				\
233 	EXPORT_SYMBOL(param_get_##name);				\
234 	EXPORT_SYMBOL(param_ops_##name)
235 
236 
237 STANDARD_PARAM_DEF(byte,	unsigned char,		"%hhu",		kstrtou8);
238 STANDARD_PARAM_DEF(short,	short,			"%hi",		kstrtos16);
239 STANDARD_PARAM_DEF(ushort,	unsigned short,		"%hu",		kstrtou16);
240 STANDARD_PARAM_DEF(int,		int,			"%i",		kstrtoint);
241 STANDARD_PARAM_DEF(uint,	unsigned int,		"%u",		kstrtouint);
242 STANDARD_PARAM_DEF(long,	long,			"%li",		kstrtol);
243 STANDARD_PARAM_DEF(ulong,	unsigned long,		"%lu",		kstrtoul);
244 STANDARD_PARAM_DEF(ullong,	unsigned long long,	"%llu",		kstrtoull);
245 STANDARD_PARAM_DEF(hexint,	unsigned int,		"%#08x", 	kstrtouint);
246 
param_set_uint_minmax(const char * val,const struct kernel_param * kp,unsigned int min,unsigned int max)247 int param_set_uint_minmax(const char *val, const struct kernel_param *kp,
248 		unsigned int min, unsigned int max)
249 {
250 	unsigned int num;
251 	int ret;
252 
253 	if (!val)
254 		return -EINVAL;
255 	ret = kstrtouint(val, 0, &num);
256 	if (ret)
257 		return ret;
258 	if (num < min || num > max)
259 		return -EINVAL;
260 	*((unsigned int *)kp->arg) = num;
261 	return 0;
262 }
263 EXPORT_SYMBOL_GPL(param_set_uint_minmax);
264 
param_set_charp(const char * val,const struct kernel_param * kp)265 int param_set_charp(const char *val, const struct kernel_param *kp)
266 {
267 	if (strlen(val) > 1024) {
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 	/* This is a hack.  We can't kmalloc in early boot, and we
275 	 * don't need to; this mangled commandline is preserved. */
276 	if (slab_is_available()) {
277 		*(char **)kp->arg = kmalloc_parameter(strlen(val)+1);
278 		if (!*(char **)kp->arg)
279 			return -ENOMEM;
280 		strcpy(*(char **)kp->arg, val);
281 	} else
282 		*(const char **)kp->arg = val;
283 
284 	return 0;
285 }
286 EXPORT_SYMBOL(param_set_charp);
287 
param_get_charp(char * buffer,const struct kernel_param * kp)288 int param_get_charp(char *buffer, const struct kernel_param *kp)
289 {
290 	return scnprintf(buffer, PAGE_SIZE, "%s\n", *((char **)kp->arg));
291 }
292 EXPORT_SYMBOL(param_get_charp);
293 
param_free_charp(void * arg)294 void param_free_charp(void *arg)
295 {
296 	maybe_kfree_parameter(*((char **)arg));
297 }
298 EXPORT_SYMBOL(param_free_charp);
299 
300 const struct kernel_param_ops param_ops_charp = {
301 	.set = param_set_charp,
302 	.get = param_get_charp,
303 	.free = param_free_charp,
304 };
305 EXPORT_SYMBOL(param_ops_charp);
306 
307 /* Actually could be a bool or an int, for historical reasons. */
param_set_bool(const char * val,const struct kernel_param * kp)308 int param_set_bool(const char *val, const struct kernel_param *kp)
309 {
310 	/* No equals means "set"... */
311 	if (!val) val = "1";
312 
313 	/* One of =[yYnN01] */
314 	return kstrtobool(val, kp->arg);
315 }
316 EXPORT_SYMBOL(param_set_bool);
317 
param_get_bool(char * buffer,const struct kernel_param * kp)318 int param_get_bool(char *buffer, const struct kernel_param *kp)
319 {
320 	/* Y and N chosen as being relatively non-coder friendly */
321 	return sprintf(buffer, "%c\n", *(bool *)kp->arg ? 'Y' : 'N');
322 }
323 EXPORT_SYMBOL(param_get_bool);
324 
325 const struct kernel_param_ops param_ops_bool = {
326 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
327 	.set = param_set_bool,
328 	.get = param_get_bool,
329 };
330 EXPORT_SYMBOL(param_ops_bool);
331 
param_set_bool_enable_only(const char * val,const struct kernel_param * kp)332 int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
333 {
334 	int err;
335 	bool new_value;
336 	bool orig_value = *(bool *)kp->arg;
337 	struct kernel_param dummy_kp = *kp;
338 
339 	dummy_kp.arg = &new_value;
340 
341 	err = param_set_bool(val, &dummy_kp);
342 	if (err)
343 		return err;
344 
345 	/* Don't let them unset it once it's set! */
346 	if (!new_value && orig_value)
347 		return -EROFS;
348 
349 	if (new_value)
350 		err = param_set_bool(val, kp);
351 
352 	return err;
353 }
354 EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
355 
356 const struct kernel_param_ops param_ops_bool_enable_only = {
357 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
358 	.set = param_set_bool_enable_only,
359 	.get = param_get_bool,
360 };
361 EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
362 
363 /* This one must be bool. */
param_set_invbool(const char * val,const struct kernel_param * kp)364 int param_set_invbool(const char *val, const struct kernel_param *kp)
365 {
366 	int ret;
367 	bool boolval;
368 	struct kernel_param dummy;
369 
370 	dummy.arg = &boolval;
371 	ret = param_set_bool(val, &dummy);
372 	if (ret == 0)
373 		*(bool *)kp->arg = !boolval;
374 	return ret;
375 }
376 EXPORT_SYMBOL(param_set_invbool);
377 
param_get_invbool(char * buffer,const struct kernel_param * kp)378 int param_get_invbool(char *buffer, const struct kernel_param *kp)
379 {
380 	return sprintf(buffer, "%c\n", (*(bool *)kp->arg) ? 'N' : 'Y');
381 }
382 EXPORT_SYMBOL(param_get_invbool);
383 
384 const struct kernel_param_ops param_ops_invbool = {
385 	.set = param_set_invbool,
386 	.get = param_get_invbool,
387 };
388 EXPORT_SYMBOL(param_ops_invbool);
389 
param_set_bint(const char * val,const struct kernel_param * kp)390 int param_set_bint(const char *val, const struct kernel_param *kp)
391 {
392 	/* Match bool exactly, by re-using it. */
393 	struct kernel_param boolkp = *kp;
394 	bool v;
395 	int ret;
396 
397 	boolkp.arg = &v;
398 
399 	ret = param_set_bool(val, &boolkp);
400 	if (ret == 0)
401 		*(int *)kp->arg = v;
402 	return ret;
403 }
404 EXPORT_SYMBOL(param_set_bint);
405 
406 const struct kernel_param_ops param_ops_bint = {
407 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
408 	.set = param_set_bint,
409 	.get = param_get_int,
410 };
411 EXPORT_SYMBOL(param_ops_bint);
412 
413 /* 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)414 static int param_array(struct module *mod,
415 		       const char *name,
416 		       const char *val,
417 		       unsigned int min, unsigned int max,
418 		       void *elem, int elemsize,
419 		       int (*set)(const char *, const struct kernel_param *kp),
420 		       s16 level,
421 		       unsigned int *num)
422 {
423 	int ret;
424 	struct kernel_param kp;
425 	char save;
426 
427 	/* Get the name right for errors. */
428 	kp.name = name;
429 	kp.arg = elem;
430 	kp.level = level;
431 
432 	*num = 0;
433 	/* We expect a comma-separated list of values. */
434 	do {
435 		int len;
436 
437 		if (*num == max) {
438 			pr_err("%s: can only take %i arguments\n", name, max);
439 			return -EINVAL;
440 		}
441 		len = strcspn(val, ",");
442 
443 		/* nul-terminate and parse */
444 		save = val[len];
445 		((char *)val)[len] = '\0';
446 		check_kparam_locked(mod);
447 		ret = set(val, &kp);
448 
449 		if (ret != 0)
450 			return ret;
451 		kp.arg += elemsize;
452 		val += len+1;
453 		(*num)++;
454 	} while (save == ',');
455 
456 	if (*num < min) {
457 		pr_err("%s: needs at least %i arguments\n", name, min);
458 		return -EINVAL;
459 	}
460 	return 0;
461 }
462 
param_array_set(const char * val,const struct kernel_param * kp)463 static int param_array_set(const char *val, const struct kernel_param *kp)
464 {
465 	const struct kparam_array *arr = kp->arr;
466 	unsigned int temp_num;
467 
468 	return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
469 			   arr->elemsize, arr->ops->set, kp->level,
470 			   arr->num ?: &temp_num);
471 }
472 
param_array_get(char * buffer,const struct kernel_param * kp)473 static int param_array_get(char *buffer, const struct kernel_param *kp)
474 {
475 	int i, off, ret;
476 	const struct kparam_array *arr = kp->arr;
477 	struct kernel_param p = *kp;
478 
479 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
480 		/* Replace \n with comma */
481 		if (i)
482 			buffer[off - 1] = ',';
483 		p.arg = arr->elem + arr->elemsize * i;
484 		check_kparam_locked(p.mod);
485 		ret = arr->ops->get(buffer + off, &p);
486 		if (ret < 0)
487 			return ret;
488 		off += ret;
489 	}
490 	buffer[off] = '\0';
491 	return off;
492 }
493 
param_array_free(void * arg)494 static void param_array_free(void *arg)
495 {
496 	unsigned int i;
497 	const struct kparam_array *arr = arg;
498 
499 	if (arr->ops->free)
500 		for (i = 0; i < (arr->num ? *arr->num : arr->max); i++)
501 			arr->ops->free(arr->elem + arr->elemsize * i);
502 }
503 
504 const struct kernel_param_ops param_array_ops = {
505 	.set = param_array_set,
506 	.get = param_array_get,
507 	.free = param_array_free,
508 };
509 EXPORT_SYMBOL(param_array_ops);
510 
param_set_copystring(const char * val,const struct kernel_param * kp)511 int param_set_copystring(const char *val, const struct kernel_param *kp)
512 {
513 	const struct kparam_string *kps = kp->str;
514 
515 	if (strlen(val)+1 > kps->maxlen) {
516 		pr_err("%s: string doesn't fit in %u chars.\n",
517 		       kp->name, kps->maxlen-1);
518 		return -ENOSPC;
519 	}
520 	strcpy(kps->string, val);
521 	return 0;
522 }
523 EXPORT_SYMBOL(param_set_copystring);
524 
param_get_string(char * buffer,const struct kernel_param * kp)525 int param_get_string(char *buffer, const struct kernel_param *kp)
526 {
527 	const struct kparam_string *kps = kp->str;
528 	return scnprintf(buffer, PAGE_SIZE, "%s\n", kps->string);
529 }
530 EXPORT_SYMBOL(param_get_string);
531 
532 const struct kernel_param_ops param_ops_string = {
533 	.set = param_set_copystring,
534 	.get = param_get_string,
535 };
536 EXPORT_SYMBOL(param_ops_string);
537 
538 /* sysfs output in /sys/modules/XYZ/parameters/ */
539 #define to_module_attr(n) container_of(n, struct module_attribute, attr)
540 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj)
541 
542 struct param_attribute
543 {
544 	struct module_attribute mattr;
545 	const struct kernel_param *param;
546 };
547 
548 struct module_param_attrs
549 {
550 	unsigned int num;
551 	struct attribute_group grp;
552 	struct param_attribute attrs[];
553 };
554 
555 #ifdef CONFIG_SYSFS
556 #define to_param_attr(n) container_of(n, struct param_attribute, mattr)
557 
param_attr_show(struct module_attribute * mattr,struct module_kobject * mk,char * buf)558 static ssize_t param_attr_show(struct module_attribute *mattr,
559 			       struct module_kobject *mk, char *buf)
560 {
561 	int count;
562 	struct param_attribute *attribute = to_param_attr(mattr);
563 
564 	if (!attribute->param->ops->get)
565 		return -EPERM;
566 
567 	kernel_param_lock(mk->mod);
568 	count = attribute->param->ops->get(buf, attribute->param);
569 	kernel_param_unlock(mk->mod);
570 	return count;
571 }
572 
573 /* 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)574 static ssize_t param_attr_store(struct module_attribute *mattr,
575 				struct module_kobject *mk,
576 				const char *buf, size_t len)
577 {
578  	int err;
579 	struct param_attribute *attribute = to_param_attr(mattr);
580 
581 	if (!attribute->param->ops->set)
582 		return -EPERM;
583 
584 	kernel_param_lock(mk->mod);
585 	if (param_check_unsafe(attribute->param))
586 		err = attribute->param->ops->set(buf, attribute->param);
587 	else
588 		err = -EPERM;
589 	kernel_param_unlock(mk->mod);
590 	if (!err)
591 		return len;
592 	return err;
593 }
594 #endif
595 
596 #ifdef CONFIG_MODULES
597 #define __modinit
598 #else
599 #define __modinit __init
600 #endif
601 
602 #ifdef CONFIG_SYSFS
kernel_param_lock(struct module * mod)603 void kernel_param_lock(struct module *mod)
604 {
605 	mutex_lock(KPARAM_MUTEX(mod));
606 }
607 
kernel_param_unlock(struct module * mod)608 void kernel_param_unlock(struct module *mod)
609 {
610 	mutex_unlock(KPARAM_MUTEX(mod));
611 }
612 
613 EXPORT_SYMBOL(kernel_param_lock);
614 EXPORT_SYMBOL(kernel_param_unlock);
615 
616 /*
617  * add_sysfs_param - add a parameter to sysfs
618  * @mk: struct module_kobject
619  * @kp: the actual parameter definition to add to sysfs
620  * @name: name of parameter
621  *
622  * Create a kobject if for a (per-module) parameter if mp NULL, and
623  * create file in sysfs.  Returns an error on out of memory.  Always cleans up
624  * if there's an error.
625  */
add_sysfs_param(struct module_kobject * mk,const struct kernel_param * kp,const char * name)626 static __modinit int add_sysfs_param(struct module_kobject *mk,
627 				     const struct kernel_param *kp,
628 				     const char *name)
629 {
630 	struct module_param_attrs *new_mp;
631 	struct attribute **new_attrs;
632 	unsigned int i;
633 
634 	/* We don't bother calling this with invisible parameters. */
635 	BUG_ON(!kp->perm);
636 
637 	if (!mk->mp) {
638 		/* First allocation. */
639 		mk->mp = kzalloc(sizeof(*mk->mp), GFP_KERNEL);
640 		if (!mk->mp)
641 			return -ENOMEM;
642 		mk->mp->grp.name = "parameters";
643 		/* NULL-terminated attribute array. */
644 		mk->mp->grp.attrs = kzalloc(sizeof(mk->mp->grp.attrs[0]),
645 					    GFP_KERNEL);
646 		/* Caller will cleanup via free_module_param_attrs */
647 		if (!mk->mp->grp.attrs)
648 			return -ENOMEM;
649 	}
650 
651 	/* Enlarge allocations. */
652 	new_mp = krealloc(mk->mp,
653 			  sizeof(*mk->mp) +
654 			  sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),
655 			  GFP_KERNEL);
656 	if (!new_mp)
657 		return -ENOMEM;
658 	mk->mp = new_mp;
659 
660 	/* Extra pointer for NULL terminator */
661 	new_attrs = krealloc(mk->mp->grp.attrs,
662 			     sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),
663 			     GFP_KERNEL);
664 	if (!new_attrs)
665 		return -ENOMEM;
666 	mk->mp->grp.attrs = new_attrs;
667 
668 	/* Tack new one on the end. */
669 	memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));
670 	sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
671 	mk->mp->attrs[mk->mp->num].param = kp;
672 	mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
673 	/* Do not allow runtime DAC changes to make param writable. */
674 	if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
675 		mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
676 	else
677 		mk->mp->attrs[mk->mp->num].mattr.store = NULL;
678 	mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
679 	mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
680 	mk->mp->num++;
681 
682 	/* Fix up all the pointers, since krealloc can move us */
683 	for (i = 0; i < mk->mp->num; i++)
684 		mk->mp->grp.attrs[i] = &mk->mp->attrs[i].mattr.attr;
685 	mk->mp->grp.attrs[mk->mp->num] = NULL;
686 	return 0;
687 }
688 
689 #ifdef CONFIG_MODULES
free_module_param_attrs(struct module_kobject * mk)690 static void free_module_param_attrs(struct module_kobject *mk)
691 {
692 	if (mk->mp)
693 		kfree(mk->mp->grp.attrs);
694 	kfree(mk->mp);
695 	mk->mp = NULL;
696 }
697 
698 /*
699  * module_param_sysfs_setup - setup sysfs support for one module
700  * @mod: module
701  * @kparam: module parameters (array)
702  * @num_params: number of module parameters
703  *
704  * Adds sysfs entries for module parameters under
705  * /sys/module/[mod->name]/parameters/
706  */
module_param_sysfs_setup(struct module * mod,const struct kernel_param * kparam,unsigned int num_params)707 int module_param_sysfs_setup(struct module *mod,
708 			     const struct kernel_param *kparam,
709 			     unsigned int num_params)
710 {
711 	int i, err;
712 	bool params = false;
713 
714 	for (i = 0; i < num_params; i++) {
715 		if (kparam[i].perm == 0)
716 			continue;
717 		err = add_sysfs_param(&mod->mkobj, &kparam[i], kparam[i].name);
718 		if (err) {
719 			free_module_param_attrs(&mod->mkobj);
720 			return err;
721 		}
722 		params = true;
723 	}
724 
725 	if (!params)
726 		return 0;
727 
728 	/* Create the param group. */
729 	err = sysfs_create_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
730 	if (err)
731 		free_module_param_attrs(&mod->mkobj);
732 	return err;
733 }
734 
735 /*
736  * module_param_sysfs_remove - remove sysfs support for one module
737  * @mod: module
738  *
739  * Remove sysfs entries for module parameters and the corresponding
740  * kobject.
741  */
module_param_sysfs_remove(struct module * mod)742 void module_param_sysfs_remove(struct module *mod)
743 {
744 	if (mod->mkobj.mp) {
745 		sysfs_remove_group(&mod->mkobj.kobj, &mod->mkobj.mp->grp);
746 		/* We are positive that no one is using any param
747 		 * attrs at this point.  Deallocate immediately. */
748 		free_module_param_attrs(&mod->mkobj);
749 	}
750 }
751 #endif
752 
destroy_params(const struct kernel_param * params,unsigned num)753 void destroy_params(const struct kernel_param *params, unsigned num)
754 {
755 	unsigned int i;
756 
757 	for (i = 0; i < num; i++)
758 		if (params[i].ops->free)
759 			params[i].ops->free(params[i].arg);
760 }
761 
locate_module_kobject(const char * name)762 static struct module_kobject * __init locate_module_kobject(const char *name)
763 {
764 	struct module_kobject *mk;
765 	struct kobject *kobj;
766 	int err;
767 
768 	kobj = kset_find_obj(module_kset, name);
769 	if (kobj) {
770 		mk = to_module_kobject(kobj);
771 	} else {
772 		mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
773 		BUG_ON(!mk);
774 
775 		mk->mod = THIS_MODULE;
776 		mk->kobj.kset = module_kset;
777 		err = kobject_init_and_add(&mk->kobj, &module_ktype, NULL,
778 					   "%s", name);
779 #ifdef CONFIG_MODULES
780 		if (!err)
781 			err = sysfs_create_file(&mk->kobj, &module_uevent.attr);
782 #endif
783 		if (err) {
784 			kobject_put(&mk->kobj);
785 			pr_crit("Adding module '%s' to sysfs failed (%d), the system may be unstable.\n",
786 				name, err);
787 			return NULL;
788 		}
789 
790 		/* So that we hold reference in both cases. */
791 		kobject_get(&mk->kobj);
792 	}
793 
794 	return mk;
795 }
796 
kernel_add_sysfs_param(const char * name,const struct kernel_param * kparam,unsigned int name_skip)797 static void __init kernel_add_sysfs_param(const char *name,
798 					  const struct kernel_param *kparam,
799 					  unsigned int name_skip)
800 {
801 	struct module_kobject *mk;
802 	int err;
803 
804 	mk = locate_module_kobject(name);
805 	if (!mk)
806 		return;
807 
808 	/* We need to remove old parameters before adding more. */
809 	if (mk->mp)
810 		sysfs_remove_group(&mk->kobj, &mk->mp->grp);
811 
812 	/* These should not fail at boot. */
813 	err = add_sysfs_param(mk, kparam, kparam->name + name_skip);
814 	BUG_ON(err);
815 	err = sysfs_create_group(&mk->kobj, &mk->mp->grp);
816 	BUG_ON(err);
817 	kobject_uevent(&mk->kobj, KOBJ_ADD);
818 	kobject_put(&mk->kobj);
819 }
820 
821 /*
822  * param_sysfs_builtin - add sysfs parameters for built-in modules
823  *
824  * Add module_parameters to sysfs for "modules" built into the kernel.
825  *
826  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
827  * "parameter" name is stored behind a dot in kernel_param->name. So,
828  * extract the "module" name for all built-in kernel_param-eters,
829  * and for all who have the same, call kernel_add_sysfs_param.
830  */
param_sysfs_builtin(void)831 static void __init param_sysfs_builtin(void)
832 {
833 	const struct kernel_param *kp;
834 	unsigned int name_len;
835 	char modname[MODULE_NAME_LEN];
836 
837 	for (kp = __start___param; kp < __stop___param; kp++) {
838 		char *dot;
839 
840 		if (kp->perm == 0)
841 			continue;
842 
843 		dot = strchr(kp->name, '.');
844 		if (!dot) {
845 			/* This happens for core_param() */
846 			strcpy(modname, "kernel");
847 			name_len = 0;
848 		} else {
849 			name_len = dot - kp->name + 1;
850 			strscpy(modname, kp->name, name_len);
851 		}
852 		kernel_add_sysfs_param(modname, kp, name_len);
853 	}
854 }
855 
__modver_version_show(struct module_attribute * mattr,struct module_kobject * mk,char * buf)856 ssize_t __modver_version_show(struct module_attribute *mattr,
857 			      struct module_kobject *mk, char *buf)
858 {
859 	struct module_version_attribute *vattr =
860 		container_of(mattr, struct module_version_attribute, mattr);
861 
862 	return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version);
863 }
864 
865 extern const struct module_version_attribute __start___modver[];
866 extern const struct module_version_attribute __stop___modver[];
867 
version_sysfs_builtin(void)868 static void __init version_sysfs_builtin(void)
869 {
870 	const struct module_version_attribute *vattr;
871 	struct module_kobject *mk;
872 	int err;
873 
874 	for (vattr = __start___modver; vattr < __stop___modver; vattr++) {
875 		mk = locate_module_kobject(vattr->module_name);
876 		if (mk) {
877 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
878 			WARN_ON_ONCE(err);
879 			kobject_uevent(&mk->kobj, KOBJ_ADD);
880 			kobject_put(&mk->kobj);
881 		}
882 	}
883 }
884 
885 /* module-related sysfs stuff */
886 
module_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)887 static ssize_t module_attr_show(struct kobject *kobj,
888 				struct attribute *attr,
889 				char *buf)
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->show)
899 		return -EIO;
900 
901 	ret = attribute->show(attribute, mk, buf);
902 
903 	return ret;
904 }
905 
module_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t len)906 static ssize_t module_attr_store(struct kobject *kobj,
907 				struct attribute *attr,
908 				const char *buf, size_t len)
909 {
910 	struct module_attribute *attribute;
911 	struct module_kobject *mk;
912 	int ret;
913 
914 	attribute = to_module_attr(attr);
915 	mk = to_module_kobject(kobj);
916 
917 	if (!attribute->store)
918 		return -EIO;
919 
920 	ret = attribute->store(attribute, mk, buf, len);
921 
922 	return ret;
923 }
924 
925 static const struct sysfs_ops module_sysfs_ops = {
926 	.show = module_attr_show,
927 	.store = module_attr_store,
928 };
929 
uevent_filter(const struct kobject * kobj)930 static int uevent_filter(const struct kobject *kobj)
931 {
932 	const struct kobj_type *ktype = get_ktype(kobj);
933 
934 	if (ktype == &module_ktype)
935 		return 1;
936 	return 0;
937 }
938 
939 static const struct kset_uevent_ops module_uevent_ops = {
940 	.filter = uevent_filter,
941 };
942 
943 struct kset *module_kset;
944 
module_kobj_release(struct kobject * kobj)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 const struct kobj_type module_ktype = {
952 	.release   =	module_kobj_release,
953 	.sysfs_ops =	&module_sysfs_ops,
954 };
955 
956 /*
957  * param_sysfs_init - create "module" kset
958  *
959  * This must be done before the initramfs is unpacked and
960  * request_module() thus becomes possible, because otherwise the
961  * module load would fail in mod_sysfs_init.
962  */
param_sysfs_init(void)963 static int __init param_sysfs_init(void)
964 {
965 	module_kset = kset_create_and_add("module", &module_uevent_ops, NULL);
966 	if (!module_kset) {
967 		printk(KERN_WARNING "%s (%d): error creating kset\n",
968 			__FILE__, __LINE__);
969 		return -ENOMEM;
970 	}
971 
972 	return 0;
973 }
974 subsys_initcall(param_sysfs_init);
975 
976 /*
977  * param_sysfs_builtin_init - add sysfs version and parameter
978  * attributes for built-in modules
979  */
param_sysfs_builtin_init(void)980 static int __init param_sysfs_builtin_init(void)
981 {
982 	if (!module_kset)
983 		return -ENOMEM;
984 
985 	version_sysfs_builtin();
986 	param_sysfs_builtin();
987 
988 	return 0;
989 }
990 late_initcall(param_sysfs_builtin_init);
991 
992 #endif /* CONFIG_SYSFS */
993