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65afac7d80
e180a6b775 "param: fix charp parameters set via sysfs" fixed the case
where charp parameters written via sysfs were freed, leaving drivers
accessing random memory.
Unfortunately, storing a flag in the kparam struct was a bad idea: it's
rodata so setting it causes an oops on some archs. But that's not all:
1) module_param_array() on charp doesn't work reliably, since we use an
uninitialized temporary struct kernel_param.
2) there's a fundamental race if a module uses this parameter and then
it's changed: they will still access the old, freed, memory.
The simplest fix (ie. for 2.6.32) is to never free the memory. This
prevents all these problems, at cost of a memory leak. In practice, there
are only 18 places where a charp is writable via sysfs, and all are
root-only writable.
Reported-by: Takashi Iwai <tiwai@suse.de>
Cc: Sitsofe Wheeler <sitsofe@yahoo.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
254 lines
9.2 KiB
C
254 lines
9.2 KiB
C
#ifndef _LINUX_MODULE_PARAMS_H
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#define _LINUX_MODULE_PARAMS_H
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/* (C) Copyright 2001, 2002 Rusty Russell IBM Corporation */
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#include <linux/init.h>
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#include <linux/stringify.h>
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#include <linux/kernel.h>
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/* You can override this manually, but generally this should match the
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module name. */
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#ifdef MODULE
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#define MODULE_PARAM_PREFIX /* empty */
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#else
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#define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
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#endif
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/* Chosen so that structs with an unsigned long line up. */
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#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
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#ifdef MODULE
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#define ___module_cat(a,b) __mod_ ## a ## b
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#define __module_cat(a,b) ___module_cat(a,b)
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#define __MODULE_INFO(tag, name, info) \
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static const char __module_cat(name,__LINE__)[] \
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__used \
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__attribute__((section(".modinfo"),unused)) = __stringify(tag) "=" info
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#else /* !MODULE */
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#define __MODULE_INFO(tag, name, info)
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#endif
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#define __MODULE_PARM_TYPE(name, _type) \
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__MODULE_INFO(parmtype, name##type, #name ":" _type)
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struct kernel_param;
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/* Returns 0, or -errno. arg is in kp->arg. */
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typedef int (*param_set_fn)(const char *val, struct kernel_param *kp);
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/* Returns length written or -errno. Buffer is 4k (ie. be short!) */
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typedef int (*param_get_fn)(char *buffer, struct kernel_param *kp);
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/* Flag bits for kernel_param.flags */
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#define KPARAM_ISBOOL 2
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struct kernel_param {
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const char *name;
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u16 perm;
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u16 flags;
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param_set_fn set;
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param_get_fn get;
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union {
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void *arg;
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const struct kparam_string *str;
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const struct kparam_array *arr;
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};
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};
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/* Special one for strings we want to copy into */
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struct kparam_string {
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unsigned int maxlen;
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char *string;
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};
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/* Special one for arrays */
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struct kparam_array
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{
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unsigned int max;
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unsigned int *num;
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param_set_fn set;
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param_get_fn get;
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unsigned int elemsize;
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void *elem;
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};
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/* On alpha, ia64 and ppc64 relocations to global data cannot go into
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read-only sections (which is part of respective UNIX ABI on these
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platforms). So 'const' makes no sense and even causes compile failures
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with some compilers. */
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#if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
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#define __moduleparam_const
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#else
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#define __moduleparam_const const
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#endif
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/* This is the fundamental function for registering boot/module
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parameters. perm sets the visibility in sysfs: 000 means it's
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not there, read bits mean it's readable, write bits mean it's
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writable. */
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#define __module_param_call(prefix, name, set, get, arg, isbool, perm) \
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/* Default value instead of permissions? */ \
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static int __param_perm_check_##name __attribute__((unused)) = \
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BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \
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+ BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \
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static const char __param_str_##name[] = prefix #name; \
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static struct kernel_param __moduleparam_const __param_##name \
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__used \
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__attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
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= { __param_str_##name, perm, isbool ? KPARAM_ISBOOL : 0, \
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set, get, { arg } }
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#define module_param_call(name, set, get, arg, perm) \
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__module_param_call(MODULE_PARAM_PREFIX, \
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name, set, get, arg, \
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__same_type(*(arg), bool), perm)
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/* Helper functions: type is byte, short, ushort, int, uint, long,
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ulong, charp, bool or invbool, or XXX if you define param_get_XXX,
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param_set_XXX and param_check_XXX. */
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#define module_param_named(name, value, type, perm) \
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param_check_##type(name, &(value)); \
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module_param_call(name, param_set_##type, param_get_##type, &value, perm); \
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__MODULE_PARM_TYPE(name, #type)
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#define module_param(name, type, perm) \
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module_param_named(name, name, type, perm)
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#ifndef MODULE
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/**
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* core_param - define a historical core kernel parameter.
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* @name: the name of the cmdline and sysfs parameter (often the same as var)
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* @var: the variable
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* @type: the type (for param_set_##type and param_get_##type)
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* @perm: visibility in sysfs
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*
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* core_param is just like module_param(), but cannot be modular and
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* doesn't add a prefix (such as "printk."). This is for compatibility
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* with __setup(), and it makes sense as truly core parameters aren't
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* tied to the particular file they're in.
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*/
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#define core_param(name, var, type, perm) \
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param_check_##type(name, &(var)); \
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__module_param_call("", name, param_set_##type, param_get_##type, \
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&var, __same_type(var, bool), perm)
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#endif /* !MODULE */
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/* Actually copy string: maxlen param is usually sizeof(string). */
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#define module_param_string(name, string, len, perm) \
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static const struct kparam_string __param_string_##name \
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= { len, string }; \
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__module_param_call(MODULE_PARAM_PREFIX, name, \
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param_set_copystring, param_get_string, \
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.str = &__param_string_##name, 0, perm); \
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__MODULE_PARM_TYPE(name, "string")
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/* Called on module insert or kernel boot */
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extern int parse_args(const char *name,
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char *args,
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struct kernel_param *params,
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unsigned num,
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int (*unknown)(char *param, char *val));
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/* Called by module remove. */
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#ifdef CONFIG_SYSFS
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extern void destroy_params(const struct kernel_param *params, unsigned num);
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#else
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static inline void destroy_params(const struct kernel_param *params,
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unsigned num)
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{
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}
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#endif /* !CONFIG_SYSFS */
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/* All the helper functions */
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/* The macros to do compile-time type checking stolen from Jakub
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Jelinek, who IIRC came up with this idea for the 2.4 module init code. */
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#define __param_check(name, p, type) \
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static inline type *__check_##name(void) { return(p); }
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extern int param_set_byte(const char *val, struct kernel_param *kp);
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extern int param_get_byte(char *buffer, struct kernel_param *kp);
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#define param_check_byte(name, p) __param_check(name, p, unsigned char)
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extern int param_set_short(const char *val, struct kernel_param *kp);
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extern int param_get_short(char *buffer, struct kernel_param *kp);
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#define param_check_short(name, p) __param_check(name, p, short)
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extern int param_set_ushort(const char *val, struct kernel_param *kp);
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extern int param_get_ushort(char *buffer, struct kernel_param *kp);
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#define param_check_ushort(name, p) __param_check(name, p, unsigned short)
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extern int param_set_int(const char *val, struct kernel_param *kp);
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extern int param_get_int(char *buffer, struct kernel_param *kp);
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#define param_check_int(name, p) __param_check(name, p, int)
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extern int param_set_uint(const char *val, struct kernel_param *kp);
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extern int param_get_uint(char *buffer, struct kernel_param *kp);
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#define param_check_uint(name, p) __param_check(name, p, unsigned int)
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extern int param_set_long(const char *val, struct kernel_param *kp);
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extern int param_get_long(char *buffer, struct kernel_param *kp);
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#define param_check_long(name, p) __param_check(name, p, long)
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extern int param_set_ulong(const char *val, struct kernel_param *kp);
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extern int param_get_ulong(char *buffer, struct kernel_param *kp);
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#define param_check_ulong(name, p) __param_check(name, p, unsigned long)
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extern int param_set_charp(const char *val, struct kernel_param *kp);
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extern int param_get_charp(char *buffer, struct kernel_param *kp);
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#define param_check_charp(name, p) __param_check(name, p, char *)
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/* For historical reasons "bool" parameters can be (unsigned) "int". */
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extern int param_set_bool(const char *val, struct kernel_param *kp);
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extern int param_get_bool(char *buffer, struct kernel_param *kp);
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#define param_check_bool(name, p) \
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static inline void __check_##name(void) \
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{ \
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BUILD_BUG_ON(!__same_type(*(p), bool) && \
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!__same_type(*(p), unsigned int) && \
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!__same_type(*(p), int)); \
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}
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extern int param_set_invbool(const char *val, struct kernel_param *kp);
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extern int param_get_invbool(char *buffer, struct kernel_param *kp);
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#define param_check_invbool(name, p) __param_check(name, p, bool)
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/* Comma-separated array: *nump is set to number they actually specified. */
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#define module_param_array_named(name, array, type, nump, perm) \
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static const struct kparam_array __param_arr_##name \
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= { ARRAY_SIZE(array), nump, param_set_##type, param_get_##type,\
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sizeof(array[0]), array }; \
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__module_param_call(MODULE_PARAM_PREFIX, name, \
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param_array_set, param_array_get, \
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.arr = &__param_arr_##name, \
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__same_type(array[0], bool), perm); \
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__MODULE_PARM_TYPE(name, "array of " #type)
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#define module_param_array(name, type, nump, perm) \
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module_param_array_named(name, name, type, nump, perm)
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extern int param_array_set(const char *val, struct kernel_param *kp);
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extern int param_array_get(char *buffer, struct kernel_param *kp);
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extern int param_set_copystring(const char *val, struct kernel_param *kp);
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extern int param_get_string(char *buffer, struct kernel_param *kp);
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/* for exporting parameters in /sys/parameters */
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struct module;
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#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
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extern int module_param_sysfs_setup(struct module *mod,
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struct kernel_param *kparam,
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unsigned int num_params);
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extern void module_param_sysfs_remove(struct module *mod);
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#else
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static inline int module_param_sysfs_setup(struct module *mod,
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struct kernel_param *kparam,
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unsigned int num_params)
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{
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return 0;
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}
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static inline void module_param_sysfs_remove(struct module *mod)
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{ }
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#endif
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#endif /* _LINUX_MODULE_PARAMS_H */
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