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linux-next/include/linux/moduleparam.h
Rusty Russell e180a6b775 param: fix charp parameters set via sysfs 
Impact: fix crash on reading from /sys/module/.../ieee80211_default_rc_algo

The module_param type "charp" simply sets a char * pointer in the
module to the parameter in the commandline string: this is why we keep
the (mangled) module command line around.  But when set via sysfs (as
about 11 charp parameters can be) this memory is freed on the way
out of the write().  Future reads hit random mem.

So we kstrdup instead: we have to check we're not in early commandline
parsing, and we have to note when we've used it so we can reliably
kfree the parameter when it's next overwritten, and also on module
unload.

(Thanks to Randy Dunlap for CONFIG_SYSFS=n fixes)

Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Diagnosed-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2009-03-31 13:05:30 +10:30

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#ifndef _LINUX_MODULE_PARAMS_H
#define _LINUX_MODULE_PARAMS_H
/* (C) Copyright 2001, 2002 Rusty Russell IBM Corporation */
#include <linux/init.h>
#include <linux/stringify.h>
#include <linux/kernel.h>
/* You can override this manually, but generally this should match the
module name. */
#ifdef MODULE
#define MODULE_PARAM_PREFIX /* empty */
#else
#define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
#endif
/* Chosen so that structs with an unsigned long line up. */
#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
#ifdef MODULE
#define ___module_cat(a,b) __mod_ ## a ## b
#define __module_cat(a,b) ___module_cat(a,b)
#define __MODULE_INFO(tag, name, info) \
static const char __module_cat(name,__LINE__)[] \
__used \
__attribute__((section(".modinfo"),unused)) = __stringify(tag) "=" info
#else /* !MODULE */
#define __MODULE_INFO(tag, name, info)
#endif
#define __MODULE_PARM_TYPE(name, _type) \
__MODULE_INFO(parmtype, name##type, #name ":" _type)
struct kernel_param;
/* Returns 0, or -errno. arg is in kp->arg. */
typedef int (*param_set_fn)(const char *val, struct kernel_param *kp);
/* Returns length written or -errno. Buffer is 4k (ie. be short!) */
typedef int (*param_get_fn)(char *buffer, struct kernel_param *kp);
struct kernel_param {
const char *name;
unsigned int perm;
param_set_fn set;
param_get_fn get;
union {
void *arg;
const struct kparam_string *str;
const struct kparam_array *arr;
};
};
/* Special one for strings we want to copy into */
struct kparam_string {
unsigned int maxlen;
char *string;
};
/* Special one for arrays */
struct kparam_array
{
unsigned int max;
unsigned int *num;
param_set_fn set;
param_get_fn get;
unsigned int elemsize;
void *elem;
};
/* On alpha, ia64 and ppc64 relocations to global data cannot go into
read-only sections (which is part of respective UNIX ABI on these
platforms). So 'const' makes no sense and even causes compile failures
with some compilers. */
#if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
#define __moduleparam_const
#else
#define __moduleparam_const const
#endif
/* This is the fundamental function for registering boot/module
parameters. perm sets the visibility in sysfs: 000 means it's
not there, read bits mean it's readable, write bits mean it's
writable. */
#define __module_param_call(prefix, name, set, get, arg, perm) \
/* Default value instead of permissions? */ \
static int __param_perm_check_##name __attribute__((unused)) = \
BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \
+ BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \
static const char __param_str_##name[] = prefix #name; \
static struct kernel_param __moduleparam_const __param_##name \
__used \
__attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
= { __param_str_##name, perm, set, get, { arg } }
#define module_param_call(name, set, get, arg, perm) \
__module_param_call(MODULE_PARAM_PREFIX, name, set, get, arg, perm)
/* Helper functions: type is byte, short, ushort, int, uint, long,
ulong, charp, bool or invbool, or XXX if you define param_get_XXX,
param_set_XXX and param_check_XXX. */
#define module_param_named(name, value, type, perm) \
param_check_##type(name, &(value)); \
module_param_call(name, param_set_##type, param_get_##type, &value, perm); \
__MODULE_PARM_TYPE(name, #type)
#define module_param(name, type, perm) \
module_param_named(name, name, type, perm)
#ifndef MODULE
/**
* core_param - define a historical core kernel parameter.
* @name: the name of the cmdline and sysfs parameter (often the same as var)
* @var: the variable
* @type: the type (for param_set_##type and param_get_##type)
* @perm: visibility in sysfs
*
* core_param is just like module_param(), but cannot be modular and
* doesn't add a prefix (such as "printk."). This is for compatibility
* with __setup(), and it makes sense as truly core parameters aren't
* tied to the particular file they're in.
*/
#define core_param(name, var, type, perm) \
param_check_##type(name, &(var)); \
__module_param_call("", name, param_set_##type, param_get_##type, \
&var, perm)
#endif /* !MODULE */
/* Actually copy string: maxlen param is usually sizeof(string). */
#define module_param_string(name, string, len, perm) \
static const struct kparam_string __param_string_##name \
= { len, string }; \
module_param_call(name, param_set_copystring, param_get_string, \
.str = &__param_string_##name, perm); \
__MODULE_PARM_TYPE(name, "string")
/* Called on module insert or kernel boot */
extern int parse_args(const char *name,
char *args,
struct kernel_param *params,
unsigned num,
int (*unknown)(char *param, char *val));
/* Called by module remove. */
#ifdef CONFIG_SYSFS
extern void destroy_params(const struct kernel_param *params, unsigned num);
#else
static inline void destroy_params(const struct kernel_param *params,
unsigned num)
{
}
#endif /* !CONFIG_SYSFS */
/* All the helper functions */
/* The macros to do compile-time type checking stolen from Jakub
Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
#define __param_check(name, p, type) \
static inline type *__check_##name(void) { return(p); }
extern int param_set_byte(const char *val, struct kernel_param *kp);
extern int param_get_byte(char *buffer, struct kernel_param *kp);
#define param_check_byte(name, p) __param_check(name, p, unsigned char)
extern int param_set_short(const char *val, struct kernel_param *kp);
extern int param_get_short(char *buffer, struct kernel_param *kp);
#define param_check_short(name, p) __param_check(name, p, short)
extern int param_set_ushort(const char *val, struct kernel_param *kp);
extern int param_get_ushort(char *buffer, struct kernel_param *kp);
#define param_check_ushort(name, p) __param_check(name, p, unsigned short)
extern int param_set_int(const char *val, struct kernel_param *kp);
extern int param_get_int(char *buffer, struct kernel_param *kp);
#define param_check_int(name, p) __param_check(name, p, int)
extern int param_set_uint(const char *val, struct kernel_param *kp);
extern int param_get_uint(char *buffer, struct kernel_param *kp);
#define param_check_uint(name, p) __param_check(name, p, unsigned int)
extern int param_set_long(const char *val, struct kernel_param *kp);
extern int param_get_long(char *buffer, struct kernel_param *kp);
#define param_check_long(name, p) __param_check(name, p, long)
extern int param_set_ulong(const char *val, struct kernel_param *kp);
extern int param_get_ulong(char *buffer, struct kernel_param *kp);
#define param_check_ulong(name, p) __param_check(name, p, unsigned long)
extern int param_set_charp(const char *val, struct kernel_param *kp);
extern int param_get_charp(char *buffer, struct kernel_param *kp);
#define param_check_charp(name, p) __param_check(name, p, char *)
extern int param_set_bool(const char *val, struct kernel_param *kp);
extern int param_get_bool(char *buffer, struct kernel_param *kp);
#define param_check_bool(name, p) __param_check(name, p, int)
extern int param_set_invbool(const char *val, struct kernel_param *kp);
extern int param_get_invbool(char *buffer, struct kernel_param *kp);
#define param_check_invbool(name, p) __param_check(name, p, int)
/* Comma-separated array: *nump is set to number they actually specified. */
#define module_param_array_named(name, array, type, nump, perm) \
static const struct kparam_array __param_arr_##name \
= { ARRAY_SIZE(array), nump, param_set_##type, param_get_##type,\
sizeof(array[0]), array }; \
module_param_call(name, param_array_set, param_array_get, \
.arr = &__param_arr_##name, perm); \
__MODULE_PARM_TYPE(name, "array of " #type)
#define module_param_array(name, type, nump, perm) \
module_param_array_named(name, name, type, nump, perm)
extern int param_array_set(const char *val, struct kernel_param *kp);
extern int param_array_get(char *buffer, struct kernel_param *kp);
extern int param_set_copystring(const char *val, struct kernel_param *kp);
extern int param_get_string(char *buffer, struct kernel_param *kp);
/* for exporting parameters in /sys/parameters */
struct module;
#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
extern int module_param_sysfs_setup(struct module *mod,
struct kernel_param *kparam,
unsigned int num_params);
extern void module_param_sysfs_remove(struct module *mod);
#else
static inline int module_param_sysfs_setup(struct module *mod,
struct kernel_param *kparam,
unsigned int num_params)
{
return 0;
}
static inline void module_param_sysfs_remove(struct module *mod)
{ }
#endif
#endif /* _LINUX_MODULE_PARAMS_H */
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