xref: /linux/kernel/params.c (revision b0148a98ec5151fec82064d95f11eb9efbc628ea)
1 /* Helpers for initial module or kernel cmdline parsing
2    Copyright (C) 2001 Rusty Russell.
3 
4     This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU General Public License as published by
6     the Free Software Foundation; either version 2 of the License, or
7     (at your option) any later version.
8 
9     This program is distributed in the hope that it will be useful,
10     but WITHOUT ANY WARRANTY; without even the implied warranty of
11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12     GNU General Public License for more details.
13 
14     You should have received a copy of the GNU General Public License
15     along with this program; if not, write to the Free Software
16     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17 */
18 #include <linux/moduleparam.h>
19 #include <linux/kernel.h>
20 #include <linux/string.h>
21 #include <linux/errno.h>
22 #include <linux/module.h>
23 #include <linux/device.h>
24 #include <linux/err.h>
25 #include <linux/slab.h>
26 
27 #if 0
28 #define DEBUGP printk
29 #else
30 #define DEBUGP(fmt, a...)
31 #endif
32 
33 static struct kobj_type module_ktype;
34 
35 static inline char dash2underscore(char c)
36 {
37 	if (c == '-')
38 		return '_';
39 	return c;
40 }
41 
42 static inline int parameq(const char *input, const char *paramname)
43 {
44 	unsigned int i;
45 	for (i = 0; dash2underscore(input[i]) == paramname[i]; i++)
46 		if (input[i] == '\0')
47 			return 1;
48 	return 0;
49 }
50 
51 static int parse_one(char *param,
52 		     char *val,
53 		     struct kernel_param *params,
54 		     unsigned num_params,
55 		     int (*handle_unknown)(char *param, char *val))
56 {
57 	unsigned int i;
58 
59 	/* Find parameter */
60 	for (i = 0; i < num_params; i++) {
61 		if (parameq(param, params[i].name)) {
62 			DEBUGP("They are equal!  Calling %p\n",
63 			       params[i].set);
64 			return params[i].set(val, &params[i]);
65 		}
66 	}
67 
68 	if (handle_unknown) {
69 		DEBUGP("Unknown argument: calling %p\n", handle_unknown);
70 		return handle_unknown(param, val);
71 	}
72 
73 	DEBUGP("Unknown argument `%s'\n", param);
74 	return -ENOENT;
75 }
76 
77 /* You can use " around spaces, but can't escape ". */
78 /* Hyphens and underscores equivalent in parameter names. */
79 static char *next_arg(char *args, char **param, char **val)
80 {
81 	unsigned int i, equals = 0;
82 	int in_quote = 0, quoted = 0;
83 	char *next;
84 
85 	if (*args == '"') {
86 		args++;
87 		in_quote = 1;
88 		quoted = 1;
89 	}
90 
91 	for (i = 0; args[i]; i++) {
92 		if (args[i] == ' ' && !in_quote)
93 			break;
94 		if (equals == 0) {
95 			if (args[i] == '=')
96 				equals = i;
97 		}
98 		if (args[i] == '"')
99 			in_quote = !in_quote;
100 	}
101 
102 	*param = args;
103 	if (!equals)
104 		*val = NULL;
105 	else {
106 		args[equals] = '\0';
107 		*val = args + equals + 1;
108 
109 		/* Don't include quotes in value. */
110 		if (**val == '"') {
111 			(*val)++;
112 			if (args[i-1] == '"')
113 				args[i-1] = '\0';
114 		}
115 		if (quoted && args[i-1] == '"')
116 			args[i-1] = '\0';
117 	}
118 
119 	if (args[i]) {
120 		args[i] = '\0';
121 		next = args + i + 1;
122 	} else
123 		next = args + i;
124 
125 	/* Chew up trailing spaces. */
126 	while (*next == ' ')
127 		next++;
128 	return next;
129 }
130 
131 /* Args looks like "foo=bar,bar2 baz=fuz wiz". */
132 int parse_args(const char *name,
133 	       char *args,
134 	       struct kernel_param *params,
135 	       unsigned num,
136 	       int (*unknown)(char *param, char *val))
137 {
138 	char *param, *val;
139 
140 	DEBUGP("Parsing ARGS: %s\n", args);
141 
142 	/* Chew leading spaces */
143 	while (*args == ' ')
144 		args++;
145 
146 	while (*args) {
147 		int ret;
148 		int irq_was_disabled;
149 
150 		args = next_arg(args, &param, &val);
151 		irq_was_disabled = irqs_disabled();
152 		ret = parse_one(param, val, params, num, unknown);
153 		if (irq_was_disabled && !irqs_disabled()) {
154 			printk(KERN_WARNING "parse_args(): option '%s' enabled "
155 					"irq's!\n", param);
156 		}
157 		switch (ret) {
158 		case -ENOENT:
159 			printk(KERN_ERR "%s: Unknown parameter `%s'\n",
160 			       name, param);
161 			return ret;
162 		case -ENOSPC:
163 			printk(KERN_ERR
164 			       "%s: `%s' too large for parameter `%s'\n",
165 			       name, val ?: "", param);
166 			return ret;
167 		case 0:
168 			break;
169 		default:
170 			printk(KERN_ERR
171 			       "%s: `%s' invalid for parameter `%s'\n",
172 			       name, val ?: "", param);
173 			return ret;
174 		}
175 	}
176 
177 	/* All parsed OK. */
178 	return 0;
179 }
180 
181 /* Lazy bastard, eh? */
182 #define STANDARD_PARAM_DEF(name, type, format, tmptype, strtolfn)      	\
183 	int param_set_##name(const char *val, struct kernel_param *kp)	\
184 	{								\
185 		char *endp;						\
186 		tmptype l;						\
187 									\
188 		if (!val) return -EINVAL;				\
189 		l = strtolfn(val, &endp, 0);				\
190 		if (endp == val || ((type)l != l))			\
191 			return -EINVAL;					\
192 		*((type *)kp->arg) = l;					\
193 		return 0;						\
194 	}								\
195 	int param_get_##name(char *buffer, struct kernel_param *kp)	\
196 	{								\
197 		return sprintf(buffer, format, *((type *)kp->arg));	\
198 	}
199 
200 STANDARD_PARAM_DEF(byte, unsigned char, "%c", unsigned long, simple_strtoul);
201 STANDARD_PARAM_DEF(short, short, "%hi", long, simple_strtol);
202 STANDARD_PARAM_DEF(ushort, unsigned short, "%hu", unsigned long, simple_strtoul);
203 STANDARD_PARAM_DEF(int, int, "%i", long, simple_strtol);
204 STANDARD_PARAM_DEF(uint, unsigned int, "%u", unsigned long, simple_strtoul);
205 STANDARD_PARAM_DEF(long, long, "%li", long, simple_strtol);
206 STANDARD_PARAM_DEF(ulong, unsigned long, "%lu", unsigned long, simple_strtoul);
207 
208 int param_set_charp(const char *val, struct kernel_param *kp)
209 {
210 	if (!val) {
211 		printk(KERN_ERR "%s: string parameter expected\n",
212 		       kp->name);
213 		return -EINVAL;
214 	}
215 
216 	if (strlen(val) > 1024) {
217 		printk(KERN_ERR "%s: string parameter too long\n",
218 		       kp->name);
219 		return -ENOSPC;
220 	}
221 
222 	*(char **)kp->arg = (char *)val;
223 	return 0;
224 }
225 
226 int param_get_charp(char *buffer, struct kernel_param *kp)
227 {
228 	return sprintf(buffer, "%s", *((char **)kp->arg));
229 }
230 
231 int param_set_bool(const char *val, struct kernel_param *kp)
232 {
233 	/* No equals means "set"... */
234 	if (!val) val = "1";
235 
236 	/* One of =[yYnN01] */
237 	switch (val[0]) {
238 	case 'y': case 'Y': case '1':
239 		*(int *)kp->arg = 1;
240 		return 0;
241 	case 'n': case 'N': case '0':
242 		*(int *)kp->arg = 0;
243 		return 0;
244 	}
245 	return -EINVAL;
246 }
247 
248 int param_get_bool(char *buffer, struct kernel_param *kp)
249 {
250 	/* Y and N chosen as being relatively non-coder friendly */
251 	return sprintf(buffer, "%c", (*(int *)kp->arg) ? 'Y' : 'N');
252 }
253 
254 int param_set_invbool(const char *val, struct kernel_param *kp)
255 {
256 	int boolval, ret;
257 	struct kernel_param dummy = { .arg = &boolval };
258 
259 	ret = param_set_bool(val, &dummy);
260 	if (ret == 0)
261 		*(int *)kp->arg = !boolval;
262 	return ret;
263 }
264 
265 int param_get_invbool(char *buffer, struct kernel_param *kp)
266 {
267 	int val;
268 	struct kernel_param dummy = { .arg = &val };
269 
270 	val = !*(int *)kp->arg;
271 	return param_get_bool(buffer, &dummy);
272 }
273 
274 /* We cheat here and temporarily mangle the string. */
275 static int param_array(const char *name,
276 		       const char *val,
277 		       unsigned int min, unsigned int max,
278 		       void *elem, int elemsize,
279 		       int (*set)(const char *, struct kernel_param *kp),
280 		       int *num)
281 {
282 	int ret;
283 	struct kernel_param kp;
284 	char save;
285 
286 	/* Get the name right for errors. */
287 	kp.name = name;
288 	kp.arg = elem;
289 
290 	/* No equals sign? */
291 	if (!val) {
292 		printk(KERN_ERR "%s: expects arguments\n", name);
293 		return -EINVAL;
294 	}
295 
296 	*num = 0;
297 	/* We expect a comma-separated list of values. */
298 	do {
299 		int len;
300 
301 		if (*num == max) {
302 			printk(KERN_ERR "%s: can only take %i arguments\n",
303 			       name, max);
304 			return -EINVAL;
305 		}
306 		len = strcspn(val, ",");
307 
308 		/* nul-terminate and parse */
309 		save = val[len];
310 		((char *)val)[len] = '\0';
311 		ret = set(val, &kp);
312 
313 		if (ret != 0)
314 			return ret;
315 		kp.arg += elemsize;
316 		val += len+1;
317 		(*num)++;
318 	} while (save == ',');
319 
320 	if (*num < min) {
321 		printk(KERN_ERR "%s: needs at least %i arguments\n",
322 		       name, min);
323 		return -EINVAL;
324 	}
325 	return 0;
326 }
327 
328 int param_array_set(const char *val, struct kernel_param *kp)
329 {
330 	struct kparam_array *arr = kp->arg;
331 	unsigned int temp_num;
332 
333 	return param_array(kp->name, val, 1, arr->max, arr->elem,
334 			   arr->elemsize, arr->set, arr->num ?: &temp_num);
335 }
336 
337 int param_array_get(char *buffer, struct kernel_param *kp)
338 {
339 	int i, off, ret;
340 	struct kparam_array *arr = kp->arg;
341 	struct kernel_param p;
342 
343 	p = *kp;
344 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
345 		if (i)
346 			buffer[off++] = ',';
347 		p.arg = arr->elem + arr->elemsize * i;
348 		ret = arr->get(buffer + off, &p);
349 		if (ret < 0)
350 			return ret;
351 		off += ret;
352 	}
353 	buffer[off] = '\0';
354 	return off;
355 }
356 
357 int param_set_copystring(const char *val, struct kernel_param *kp)
358 {
359 	struct kparam_string *kps = kp->arg;
360 
361 	if (strlen(val)+1 > kps->maxlen) {
362 		printk(KERN_ERR "%s: string doesn't fit in %u chars.\n",
363 		       kp->name, kps->maxlen-1);
364 		return -ENOSPC;
365 	}
366 	strcpy(kps->string, val);
367 	return 0;
368 }
369 
370 int param_get_string(char *buffer, struct kernel_param *kp)
371 {
372 	struct kparam_string *kps = kp->arg;
373 	return strlcpy(buffer, kps->string, kps->maxlen);
374 }
375 
376 /* sysfs output in /sys/modules/XYZ/parameters/ */
377 
378 extern struct kernel_param __start___param[], __stop___param[];
379 
380 #define MAX_KBUILD_MODNAME KOBJ_NAME_LEN
381 
382 struct param_attribute
383 {
384 	struct module_attribute mattr;
385 	struct kernel_param *param;
386 };
387 
388 struct module_param_attrs
389 {
390 	struct attribute_group grp;
391 	struct param_attribute attrs[0];
392 };
393 
394 #define to_param_attr(n) container_of(n, struct param_attribute, mattr);
395 
396 static ssize_t param_attr_show(struct module_attribute *mattr,
397 			       struct module *mod, char *buf)
398 {
399 	int count;
400 	struct param_attribute *attribute = to_param_attr(mattr);
401 
402 	if (!attribute->param->get)
403 		return -EPERM;
404 
405 	count = attribute->param->get(buf, attribute->param);
406 	if (count > 0) {
407 		strcat(buf, "\n");
408 		++count;
409 	}
410 	return count;
411 }
412 
413 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
414 static ssize_t param_attr_store(struct module_attribute *mattr,
415 				struct module *owner,
416 				const char *buf, size_t len)
417 {
418  	int err;
419 	struct param_attribute *attribute = to_param_attr(mattr);
420 
421 	if (!attribute->param->set)
422 		return -EPERM;
423 
424 	err = attribute->param->set(buf, attribute->param);
425 	if (!err)
426 		return len;
427 	return err;
428 }
429 
430 #ifdef CONFIG_MODULES
431 #define __modinit
432 #else
433 #define __modinit __init
434 #endif
435 
436 /*
437  * param_sysfs_setup - setup sysfs support for one module or KBUILD_MODNAME
438  * @mk: struct module_kobject (contains parent kobject)
439  * @kparam: array of struct kernel_param, the actual parameter definitions
440  * @num_params: number of entries in array
441  * @name_skip: offset where the parameter name start in kparam[].name. Needed for built-in "modules"
442  *
443  * Create a kobject for a (per-module) group of parameters, and create files
444  * in sysfs. A pointer to the param_kobject is returned on success,
445  * NULL if there's no parameter to export, or other ERR_PTR(err).
446  */
447 static __modinit struct module_param_attrs *
448 param_sysfs_setup(struct module_kobject *mk,
449 		  struct kernel_param *kparam,
450 		  unsigned int num_params,
451 		  unsigned int name_skip)
452 {
453 	struct module_param_attrs *mp;
454 	unsigned int valid_attrs = 0;
455 	unsigned int i, size[2];
456 	struct param_attribute *pattr;
457 	struct attribute **gattr;
458 	int err;
459 
460 	for (i=0; i<num_params; i++) {
461 		if (kparam[i].perm)
462 			valid_attrs++;
463 	}
464 
465 	if (!valid_attrs)
466 		return NULL;
467 
468 	size[0] = ALIGN(sizeof(*mp) +
469 			valid_attrs * sizeof(mp->attrs[0]),
470 			sizeof(mp->grp.attrs[0]));
471 	size[1] = (valid_attrs + 1) * sizeof(mp->grp.attrs[0]);
472 
473 	mp = kmalloc(size[0] + size[1], GFP_KERNEL);
474 	if (!mp)
475 		return ERR_PTR(-ENOMEM);
476 
477 	mp->grp.name = "parameters";
478 	mp->grp.attrs = (void *)mp + size[0];
479 
480 	pattr = &mp->attrs[0];
481 	gattr = &mp->grp.attrs[0];
482 	for (i = 0; i < num_params; i++) {
483 		struct kernel_param *kp = &kparam[i];
484 		if (kp->perm) {
485 			pattr->param = kp;
486 			pattr->mattr.show = param_attr_show;
487 			pattr->mattr.store = param_attr_store;
488 			pattr->mattr.attr.name = (char *)&kp->name[name_skip];
489 			pattr->mattr.attr.owner = mk->mod;
490 			pattr->mattr.attr.mode = kp->perm;
491 			*(gattr++) = &(pattr++)->mattr.attr;
492 		}
493 	}
494 	*gattr = NULL;
495 
496 	if ((err = sysfs_create_group(&mk->kobj, &mp->grp))) {
497 		kfree(mp);
498 		return ERR_PTR(err);
499 	}
500 	return mp;
501 }
502 
503 
504 #ifdef CONFIG_MODULES
505 
506 /*
507  * module_param_sysfs_setup - setup sysfs support for one module
508  * @mod: module
509  * @kparam: module parameters (array)
510  * @num_params: number of module parameters
511  *
512  * Adds sysfs entries for module parameters, and creates a link from
513  * /sys/module/[mod->name]/parameters to /sys/parameters/[mod->name]/
514  */
515 int module_param_sysfs_setup(struct module *mod,
516 			     struct kernel_param *kparam,
517 			     unsigned int num_params)
518 {
519 	struct module_param_attrs *mp;
520 
521 	mp = param_sysfs_setup(&mod->mkobj, kparam, num_params, 0);
522 	if (IS_ERR(mp))
523 		return PTR_ERR(mp);
524 
525 	mod->param_attrs = mp;
526 	return 0;
527 }
528 
529 /*
530  * module_param_sysfs_remove - remove sysfs support for one module
531  * @mod: module
532  *
533  * Remove sysfs entries for module parameters and the corresponding
534  * kobject.
535  */
536 void module_param_sysfs_remove(struct module *mod)
537 {
538 	if (mod->param_attrs) {
539 		sysfs_remove_group(&mod->mkobj.kobj,
540 				   &mod->param_attrs->grp);
541 		/* We are positive that no one is using any param
542 		 * attrs at this point.  Deallocate immediately. */
543 		kfree(mod->param_attrs);
544 		mod->param_attrs = NULL;
545 	}
546 }
547 #endif
548 
549 /*
550  * kernel_param_sysfs_setup - wrapper for built-in params support
551  */
552 static void __init kernel_param_sysfs_setup(const char *name,
553 					    struct kernel_param *kparam,
554 					    unsigned int num_params,
555 					    unsigned int name_skip)
556 {
557 	struct module_kobject *mk;
558 	int ret;
559 
560 	mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL);
561 	BUG_ON(!mk);
562 
563 	mk->mod = THIS_MODULE;
564 	kobj_set_kset_s(mk, module_subsys);
565 	kobject_set_name(&mk->kobj, name);
566 	kobject_init(&mk->kobj);
567 	ret = kobject_add(&mk->kobj);
568 	BUG_ON(ret < 0);
569 	param_sysfs_setup(mk, kparam, num_params, name_skip);
570 	kobject_uevent(&mk->kobj, KOBJ_ADD);
571 }
572 
573 /*
574  * param_sysfs_builtin - add contents in /sys/parameters for built-in modules
575  *
576  * Add module_parameters to sysfs for "modules" built into the kernel.
577  *
578  * The "module" name (KBUILD_MODNAME) is stored before a dot, the
579  * "parameter" name is stored behind a dot in kernel_param->name. So,
580  * extract the "module" name for all built-in kernel_param-eters,
581  * and for all who have the same, call kernel_param_sysfs_setup.
582  */
583 static void __init param_sysfs_builtin(void)
584 {
585 	struct kernel_param *kp, *kp_begin = NULL;
586 	unsigned int i, name_len, count = 0;
587 	char modname[MAX_KBUILD_MODNAME + 1] = "";
588 
589 	for (i=0; i < __stop___param - __start___param; i++) {
590 		char *dot;
591 
592 		kp = &__start___param[i];
593 
594 		/* We do not handle args without periods. */
595 		dot = memchr(kp->name, '.', MAX_KBUILD_MODNAME);
596 		if (!dot) {
597 			DEBUGP("couldn't find period in %s\n", kp->name);
598 			continue;
599 		}
600 		name_len = dot - kp->name;
601 
602  		/* new kbuild_modname? */
603 		if (strlen(modname) != name_len
604 		    || strncmp(modname, kp->name, name_len) != 0) {
605 			/* add a new kobject for previous kernel_params. */
606 			if (count)
607 				kernel_param_sysfs_setup(modname,
608 							 kp_begin,
609 							 count,
610 							 strlen(modname)+1);
611 
612 			strncpy(modname, kp->name, name_len);
613 			modname[name_len] = '\0';
614 			count = 0;
615 			kp_begin = kp;
616 		}
617 		count++;
618 	}
619 
620 	/* last kernel_params need to be registered as well */
621 	if (count)
622 		kernel_param_sysfs_setup(modname, kp_begin, count,
623 					 strlen(modname)+1);
624 }
625 
626 
627 /* module-related sysfs stuff */
628 #ifdef CONFIG_SYSFS
629 
630 #define to_module_attr(n) container_of(n, struct module_attribute, attr);
631 #define to_module_kobject(n) container_of(n, struct module_kobject, kobj);
632 
633 static ssize_t module_attr_show(struct kobject *kobj,
634 				struct attribute *attr,
635 				char *buf)
636 {
637 	struct module_attribute *attribute;
638 	struct module_kobject *mk;
639 	int ret;
640 
641 	attribute = to_module_attr(attr);
642 	mk = to_module_kobject(kobj);
643 
644 	if (!attribute->show)
645 		return -EIO;
646 
647 	ret = attribute->show(attribute, mk->mod, buf);
648 
649 	return ret;
650 }
651 
652 static ssize_t module_attr_store(struct kobject *kobj,
653 				struct attribute *attr,
654 				const char *buf, size_t len)
655 {
656 	struct module_attribute *attribute;
657 	struct module_kobject *mk;
658 	int ret;
659 
660 	attribute = to_module_attr(attr);
661 	mk = to_module_kobject(kobj);
662 
663 	if (!attribute->store)
664 		return -EIO;
665 
666 	ret = attribute->store(attribute, mk->mod, buf, len);
667 
668 	return ret;
669 }
670 
671 static struct sysfs_ops module_sysfs_ops = {
672 	.show = module_attr_show,
673 	.store = module_attr_store,
674 };
675 
676 static int uevent_filter(struct kset *kset, struct kobject *kobj)
677 {
678 	struct kobj_type *ktype = get_ktype(kobj);
679 
680 	if (ktype == &module_ktype)
681 		return 1;
682 	return 0;
683 }
684 
685 static struct kset_uevent_ops module_uevent_ops = {
686 	.filter = uevent_filter,
687 };
688 
689 #else
690 static struct sysfs_ops module_sysfs_ops = {
691 	.show = NULL,
692 	.store = NULL,
693 };
694 #endif
695 
696 static struct kobj_type module_ktype = {
697 	.sysfs_ops =	&module_sysfs_ops,
698 };
699 
700 decl_subsys(module, &module_ktype, &module_uevent_ops);
701 
702 /*
703  * param_sysfs_init - wrapper for built-in params support
704  */
705 static int __init param_sysfs_init(void)
706 {
707 	int ret;
708 
709 	ret = subsystem_register(&module_subsys);
710 	if (ret < 0) {
711 		printk(KERN_WARNING "%s (%d): subsystem_register error: %d\n",
712 			__FILE__, __LINE__, ret);
713 		return ret;
714 	}
715 
716 	param_sysfs_builtin();
717 
718 	return 0;
719 }
720 subsys_initcall(param_sysfs_init);
721 
722 EXPORT_SYMBOL(param_set_byte);
723 EXPORT_SYMBOL(param_get_byte);
724 EXPORT_SYMBOL(param_set_short);
725 EXPORT_SYMBOL(param_get_short);
726 EXPORT_SYMBOL(param_set_ushort);
727 EXPORT_SYMBOL(param_get_ushort);
728 EXPORT_SYMBOL(param_set_int);
729 EXPORT_SYMBOL(param_get_int);
730 EXPORT_SYMBOL(param_set_uint);
731 EXPORT_SYMBOL(param_get_uint);
732 EXPORT_SYMBOL(param_set_long);
733 EXPORT_SYMBOL(param_get_long);
734 EXPORT_SYMBOL(param_set_ulong);
735 EXPORT_SYMBOL(param_get_ulong);
736 EXPORT_SYMBOL(param_set_charp);
737 EXPORT_SYMBOL(param_get_charp);
738 EXPORT_SYMBOL(param_set_bool);
739 EXPORT_SYMBOL(param_get_bool);
740 EXPORT_SYMBOL(param_set_invbool);
741 EXPORT_SYMBOL(param_get_invbool);
742 EXPORT_SYMBOL(param_array_set);
743 EXPORT_SYMBOL(param_array_get);
744 EXPORT_SYMBOL(param_set_copystring);
745 EXPORT_SYMBOL(param_get_string);
746