594 строки
16 KiB
C
594 строки
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* arch/arm/include/asm/uaccess.h
|
|
*/
|
|
#ifndef _ASMARM_UACCESS_H
|
|
#define _ASMARM_UACCESS_H
|
|
|
|
/*
|
|
* User space memory access functions
|
|
*/
|
|
#include <linux/string.h>
|
|
#include <asm/memory.h>
|
|
#include <asm/domain.h>
|
|
#include <asm/unified.h>
|
|
#include <asm/compiler.h>
|
|
|
|
#include <asm/extable.h>
|
|
|
|
/*
|
|
* These two functions allow hooking accesses to userspace to increase
|
|
* system integrity by ensuring that the kernel can not inadvertantly
|
|
* perform such accesses (eg, via list poison values) which could then
|
|
* be exploited for priviledge escalation.
|
|
*/
|
|
static __always_inline unsigned int uaccess_save_and_enable(void)
|
|
{
|
|
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
|
|
unsigned int old_domain = get_domain();
|
|
|
|
/* Set the current domain access to permit user accesses */
|
|
set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
|
|
domain_val(DOMAIN_USER, DOMAIN_CLIENT));
|
|
|
|
return old_domain;
|
|
#else
|
|
return 0;
|
|
#endif
|
|
}
|
|
|
|
static __always_inline void uaccess_restore(unsigned int flags)
|
|
{
|
|
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
|
|
/* Restore the user access mask */
|
|
set_domain(flags);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* These two are intentionally not defined anywhere - if the kernel
|
|
* code generates any references to them, that's a bug.
|
|
*/
|
|
extern int __get_user_bad(void);
|
|
extern int __put_user_bad(void);
|
|
|
|
/*
|
|
* Note that this is actually 0x1,0000,0000
|
|
*/
|
|
#define KERNEL_DS 0x00000000
|
|
|
|
#ifdef CONFIG_MMU
|
|
|
|
#define USER_DS TASK_SIZE
|
|
#define get_fs() (current_thread_info()->addr_limit)
|
|
|
|
static inline void set_fs(mm_segment_t fs)
|
|
{
|
|
current_thread_info()->addr_limit = fs;
|
|
|
|
/*
|
|
* Prevent a mispredicted conditional call to set_fs from forwarding
|
|
* the wrong address limit to access_ok under speculation.
|
|
*/
|
|
dsb(nsh);
|
|
isb();
|
|
|
|
modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER);
|
|
}
|
|
|
|
#define uaccess_kernel() (get_fs() == KERNEL_DS)
|
|
|
|
/*
|
|
* We use 33-bit arithmetic here. Success returns zero, failure returns
|
|
* addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS,
|
|
* so this will always return success in that case.
|
|
*/
|
|
#define __range_ok(addr, size) ({ \
|
|
unsigned long flag, roksum; \
|
|
__chk_user_ptr(addr); \
|
|
__asm__(".syntax unified\n" \
|
|
"adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \
|
|
: "=&r" (flag), "=&r" (roksum) \
|
|
: "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \
|
|
: "cc"); \
|
|
flag; })
|
|
|
|
/*
|
|
* This is a type: either unsigned long, if the argument fits into
|
|
* that type, or otherwise unsigned long long.
|
|
*/
|
|
#define __inttype(x) \
|
|
__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
|
|
|
|
/*
|
|
* Sanitise a uaccess pointer such that it becomes NULL if addr+size
|
|
* is above the current addr_limit.
|
|
*/
|
|
#define uaccess_mask_range_ptr(ptr, size) \
|
|
((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
|
|
static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
|
|
size_t size)
|
|
{
|
|
void __user *safe_ptr = (void __user *)ptr;
|
|
unsigned long tmp;
|
|
|
|
asm volatile(
|
|
" .syntax unified\n"
|
|
" sub %1, %3, #1\n"
|
|
" subs %1, %1, %0\n"
|
|
" addhs %1, %1, #1\n"
|
|
" subshs %1, %1, %2\n"
|
|
" movlo %0, #0\n"
|
|
: "+r" (safe_ptr), "=&r" (tmp)
|
|
: "r" (size), "r" (current_thread_info()->addr_limit)
|
|
: "cc");
|
|
|
|
csdb();
|
|
return safe_ptr;
|
|
}
|
|
|
|
/*
|
|
* Single-value transfer routines. They automatically use the right
|
|
* size if we just have the right pointer type. Note that the functions
|
|
* which read from user space (*get_*) need to take care not to leak
|
|
* kernel data even if the calling code is buggy and fails to check
|
|
* the return value. This means zeroing out the destination variable
|
|
* or buffer on error. Normally this is done out of line by the
|
|
* fixup code, but there are a few places where it intrudes on the
|
|
* main code path. When we only write to user space, there is no
|
|
* problem.
|
|
*/
|
|
extern int __get_user_1(void *);
|
|
extern int __get_user_2(void *);
|
|
extern int __get_user_4(void *);
|
|
extern int __get_user_32t_8(void *);
|
|
extern int __get_user_8(void *);
|
|
extern int __get_user_64t_1(void *);
|
|
extern int __get_user_64t_2(void *);
|
|
extern int __get_user_64t_4(void *);
|
|
|
|
#define __GUP_CLOBBER_1 "lr", "cc"
|
|
#ifdef CONFIG_CPU_USE_DOMAINS
|
|
#define __GUP_CLOBBER_2 "ip", "lr", "cc"
|
|
#else
|
|
#define __GUP_CLOBBER_2 "lr", "cc"
|
|
#endif
|
|
#define __GUP_CLOBBER_4 "lr", "cc"
|
|
#define __GUP_CLOBBER_32t_8 "lr", "cc"
|
|
#define __GUP_CLOBBER_8 "lr", "cc"
|
|
|
|
#define __get_user_x(__r2, __p, __e, __l, __s) \
|
|
__asm__ __volatile__ ( \
|
|
__asmeq("%0", "r0") __asmeq("%1", "r2") \
|
|
__asmeq("%3", "r1") \
|
|
"bl __get_user_" #__s \
|
|
: "=&r" (__e), "=r" (__r2) \
|
|
: "0" (__p), "r" (__l) \
|
|
: __GUP_CLOBBER_##__s)
|
|
|
|
/* narrowing a double-word get into a single 32bit word register: */
|
|
#ifdef __ARMEB__
|
|
#define __get_user_x_32t(__r2, __p, __e, __l, __s) \
|
|
__get_user_x(__r2, __p, __e, __l, 32t_8)
|
|
#else
|
|
#define __get_user_x_32t __get_user_x
|
|
#endif
|
|
|
|
/*
|
|
* storing result into proper least significant word of 64bit target var,
|
|
* different only for big endian case where 64 bit __r2 lsw is r3:
|
|
*/
|
|
#ifdef __ARMEB__
|
|
#define __get_user_x_64t(__r2, __p, __e, __l, __s) \
|
|
__asm__ __volatile__ ( \
|
|
__asmeq("%0", "r0") __asmeq("%1", "r2") \
|
|
__asmeq("%3", "r1") \
|
|
"bl __get_user_64t_" #__s \
|
|
: "=&r" (__e), "=r" (__r2) \
|
|
: "0" (__p), "r" (__l) \
|
|
: __GUP_CLOBBER_##__s)
|
|
#else
|
|
#define __get_user_x_64t __get_user_x
|
|
#endif
|
|
|
|
|
|
#define __get_user_check(x, p) \
|
|
({ \
|
|
unsigned long __limit = current_thread_info()->addr_limit - 1; \
|
|
register typeof(*(p)) __user *__p asm("r0") = (p); \
|
|
register __inttype(x) __r2 asm("r2"); \
|
|
register unsigned long __l asm("r1") = __limit; \
|
|
register int __e asm("r0"); \
|
|
unsigned int __ua_flags = uaccess_save_and_enable(); \
|
|
switch (sizeof(*(__p))) { \
|
|
case 1: \
|
|
if (sizeof((x)) >= 8) \
|
|
__get_user_x_64t(__r2, __p, __e, __l, 1); \
|
|
else \
|
|
__get_user_x(__r2, __p, __e, __l, 1); \
|
|
break; \
|
|
case 2: \
|
|
if (sizeof((x)) >= 8) \
|
|
__get_user_x_64t(__r2, __p, __e, __l, 2); \
|
|
else \
|
|
__get_user_x(__r2, __p, __e, __l, 2); \
|
|
break; \
|
|
case 4: \
|
|
if (sizeof((x)) >= 8) \
|
|
__get_user_x_64t(__r2, __p, __e, __l, 4); \
|
|
else \
|
|
__get_user_x(__r2, __p, __e, __l, 4); \
|
|
break; \
|
|
case 8: \
|
|
if (sizeof((x)) < 8) \
|
|
__get_user_x_32t(__r2, __p, __e, __l, 4); \
|
|
else \
|
|
__get_user_x(__r2, __p, __e, __l, 8); \
|
|
break; \
|
|
default: __e = __get_user_bad(); break; \
|
|
} \
|
|
uaccess_restore(__ua_flags); \
|
|
x = (typeof(*(p))) __r2; \
|
|
__e; \
|
|
})
|
|
|
|
#define get_user(x, p) \
|
|
({ \
|
|
might_fault(); \
|
|
__get_user_check(x, p); \
|
|
})
|
|
|
|
extern int __put_user_1(void *, unsigned int);
|
|
extern int __put_user_2(void *, unsigned int);
|
|
extern int __put_user_4(void *, unsigned int);
|
|
extern int __put_user_8(void *, unsigned long long);
|
|
|
|
#define __put_user_check(__pu_val, __ptr, __err, __s) \
|
|
({ \
|
|
unsigned long __limit = current_thread_info()->addr_limit - 1; \
|
|
register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
|
|
register const void __user *__p asm("r0") = __ptr; \
|
|
register unsigned long __l asm("r1") = __limit; \
|
|
register int __e asm("r0"); \
|
|
__asm__ __volatile__ ( \
|
|
__asmeq("%0", "r0") __asmeq("%2", "r2") \
|
|
__asmeq("%3", "r1") \
|
|
"bl __put_user_" #__s \
|
|
: "=&r" (__e) \
|
|
: "0" (__p), "r" (__r2), "r" (__l) \
|
|
: "ip", "lr", "cc"); \
|
|
__err = __e; \
|
|
})
|
|
|
|
#else /* CONFIG_MMU */
|
|
|
|
/*
|
|
* uClinux has only one addr space, so has simplified address limits.
|
|
*/
|
|
#define USER_DS KERNEL_DS
|
|
|
|
#define uaccess_kernel() (true)
|
|
#define __addr_ok(addr) ((void)(addr), 1)
|
|
#define __range_ok(addr, size) ((void)(addr), 0)
|
|
#define get_fs() (KERNEL_DS)
|
|
|
|
static inline void set_fs(mm_segment_t fs)
|
|
{
|
|
}
|
|
|
|
#define get_user(x, p) __get_user(x, p)
|
|
#define __put_user_check __put_user_nocheck
|
|
|
|
#endif /* CONFIG_MMU */
|
|
|
|
#define access_ok(addr, size) (__range_ok(addr, size) == 0)
|
|
|
|
#define user_addr_max() \
|
|
(uaccess_kernel() ? ~0UL : get_fs())
|
|
|
|
#ifdef CONFIG_CPU_SPECTRE
|
|
/*
|
|
* When mitigating Spectre variant 1, it is not worth fixing the non-
|
|
* verifying accessors, because we need to add verification of the
|
|
* address space there. Force these to use the standard get_user()
|
|
* version instead.
|
|
*/
|
|
#define __get_user(x, ptr) get_user(x, ptr)
|
|
#else
|
|
|
|
/*
|
|
* The "__xxx" versions of the user access functions do not verify the
|
|
* address space - it must have been done previously with a separate
|
|
* "access_ok()" call.
|
|
*
|
|
* The "xxx_error" versions set the third argument to EFAULT if an
|
|
* error occurs, and leave it unchanged on success. Note that these
|
|
* versions are void (ie, don't return a value as such).
|
|
*/
|
|
#define __get_user(x, ptr) \
|
|
({ \
|
|
long __gu_err = 0; \
|
|
__get_user_err((x), (ptr), __gu_err); \
|
|
__gu_err; \
|
|
})
|
|
|
|
#define __get_user_err(x, ptr, err) \
|
|
do { \
|
|
unsigned long __gu_addr = (unsigned long)(ptr); \
|
|
unsigned long __gu_val; \
|
|
unsigned int __ua_flags; \
|
|
__chk_user_ptr(ptr); \
|
|
might_fault(); \
|
|
__ua_flags = uaccess_save_and_enable(); \
|
|
switch (sizeof(*(ptr))) { \
|
|
case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \
|
|
case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \
|
|
case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \
|
|
default: (__gu_val) = __get_user_bad(); \
|
|
} \
|
|
uaccess_restore(__ua_flags); \
|
|
(x) = (__typeof__(*(ptr)))__gu_val; \
|
|
} while (0)
|
|
|
|
#define __get_user_asm(x, addr, err, instr) \
|
|
__asm__ __volatile__( \
|
|
"1: " TUSER(instr) " %1, [%2], #0\n" \
|
|
"2:\n" \
|
|
" .pushsection .text.fixup,\"ax\"\n" \
|
|
" .align 2\n" \
|
|
"3: mov %0, %3\n" \
|
|
" mov %1, #0\n" \
|
|
" b 2b\n" \
|
|
" .popsection\n" \
|
|
" .pushsection __ex_table,\"a\"\n" \
|
|
" .align 3\n" \
|
|
" .long 1b, 3b\n" \
|
|
" .popsection" \
|
|
: "+r" (err), "=&r" (x) \
|
|
: "r" (addr), "i" (-EFAULT) \
|
|
: "cc")
|
|
|
|
#define __get_user_asm_byte(x, addr, err) \
|
|
__get_user_asm(x, addr, err, ldrb)
|
|
|
|
#if __LINUX_ARM_ARCH__ >= 6
|
|
|
|
#define __get_user_asm_half(x, addr, err) \
|
|
__get_user_asm(x, addr, err, ldrh)
|
|
|
|
#else
|
|
|
|
#ifndef __ARMEB__
|
|
#define __get_user_asm_half(x, __gu_addr, err) \
|
|
({ \
|
|
unsigned long __b1, __b2; \
|
|
__get_user_asm_byte(__b1, __gu_addr, err); \
|
|
__get_user_asm_byte(__b2, __gu_addr + 1, err); \
|
|
(x) = __b1 | (__b2 << 8); \
|
|
})
|
|
#else
|
|
#define __get_user_asm_half(x, __gu_addr, err) \
|
|
({ \
|
|
unsigned long __b1, __b2; \
|
|
__get_user_asm_byte(__b1, __gu_addr, err); \
|
|
__get_user_asm_byte(__b2, __gu_addr + 1, err); \
|
|
(x) = (__b1 << 8) | __b2; \
|
|
})
|
|
#endif
|
|
|
|
#endif /* __LINUX_ARM_ARCH__ >= 6 */
|
|
|
|
#define __get_user_asm_word(x, addr, err) \
|
|
__get_user_asm(x, addr, err, ldr)
|
|
#endif
|
|
|
|
|
|
#define __put_user_switch(x, ptr, __err, __fn) \
|
|
do { \
|
|
const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
|
|
__typeof__(*(ptr)) __pu_val = (x); \
|
|
unsigned int __ua_flags; \
|
|
might_fault(); \
|
|
__ua_flags = uaccess_save_and_enable(); \
|
|
switch (sizeof(*(ptr))) { \
|
|
case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
|
|
case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
|
|
case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
|
|
case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
|
|
default: __err = __put_user_bad(); break; \
|
|
} \
|
|
uaccess_restore(__ua_flags); \
|
|
} while (0)
|
|
|
|
#define put_user(x, ptr) \
|
|
({ \
|
|
int __pu_err = 0; \
|
|
__put_user_switch((x), (ptr), __pu_err, __put_user_check); \
|
|
__pu_err; \
|
|
})
|
|
|
|
#ifdef CONFIG_CPU_SPECTRE
|
|
/*
|
|
* When mitigating Spectre variant 1.1, all accessors need to include
|
|
* verification of the address space.
|
|
*/
|
|
#define __put_user(x, ptr) put_user(x, ptr)
|
|
|
|
#else
|
|
#define __put_user(x, ptr) \
|
|
({ \
|
|
long __pu_err = 0; \
|
|
__put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
|
|
__pu_err; \
|
|
})
|
|
|
|
#define __put_user_nocheck(x, __pu_ptr, __err, __size) \
|
|
do { \
|
|
unsigned long __pu_addr = (unsigned long)__pu_ptr; \
|
|
__put_user_nocheck_##__size(x, __pu_addr, __err); \
|
|
} while (0)
|
|
|
|
#define __put_user_nocheck_1 __put_user_asm_byte
|
|
#define __put_user_nocheck_2 __put_user_asm_half
|
|
#define __put_user_nocheck_4 __put_user_asm_word
|
|
#define __put_user_nocheck_8 __put_user_asm_dword
|
|
|
|
#define __put_user_asm(x, __pu_addr, err, instr) \
|
|
__asm__ __volatile__( \
|
|
"1: " TUSER(instr) " %1, [%2], #0\n" \
|
|
"2:\n" \
|
|
" .pushsection .text.fixup,\"ax\"\n" \
|
|
" .align 2\n" \
|
|
"3: mov %0, %3\n" \
|
|
" b 2b\n" \
|
|
" .popsection\n" \
|
|
" .pushsection __ex_table,\"a\"\n" \
|
|
" .align 3\n" \
|
|
" .long 1b, 3b\n" \
|
|
" .popsection" \
|
|
: "+r" (err) \
|
|
: "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
|
|
: "cc")
|
|
|
|
#define __put_user_asm_byte(x, __pu_addr, err) \
|
|
__put_user_asm(x, __pu_addr, err, strb)
|
|
|
|
#if __LINUX_ARM_ARCH__ >= 6
|
|
|
|
#define __put_user_asm_half(x, __pu_addr, err) \
|
|
__put_user_asm(x, __pu_addr, err, strh)
|
|
|
|
#else
|
|
|
|
#ifndef __ARMEB__
|
|
#define __put_user_asm_half(x, __pu_addr, err) \
|
|
({ \
|
|
unsigned long __temp = (__force unsigned long)(x); \
|
|
__put_user_asm_byte(__temp, __pu_addr, err); \
|
|
__put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \
|
|
})
|
|
#else
|
|
#define __put_user_asm_half(x, __pu_addr, err) \
|
|
({ \
|
|
unsigned long __temp = (__force unsigned long)(x); \
|
|
__put_user_asm_byte(__temp >> 8, __pu_addr, err); \
|
|
__put_user_asm_byte(__temp, __pu_addr + 1, err); \
|
|
})
|
|
#endif
|
|
|
|
#endif /* __LINUX_ARM_ARCH__ >= 6 */
|
|
|
|
#define __put_user_asm_word(x, __pu_addr, err) \
|
|
__put_user_asm(x, __pu_addr, err, str)
|
|
|
|
#ifndef __ARMEB__
|
|
#define __reg_oper0 "%R2"
|
|
#define __reg_oper1 "%Q2"
|
|
#else
|
|
#define __reg_oper0 "%Q2"
|
|
#define __reg_oper1 "%R2"
|
|
#endif
|
|
|
|
#define __put_user_asm_dword(x, __pu_addr, err) \
|
|
__asm__ __volatile__( \
|
|
ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \
|
|
ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \
|
|
THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \
|
|
THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \
|
|
"3:\n" \
|
|
" .pushsection .text.fixup,\"ax\"\n" \
|
|
" .align 2\n" \
|
|
"4: mov %0, %3\n" \
|
|
" b 3b\n" \
|
|
" .popsection\n" \
|
|
" .pushsection __ex_table,\"a\"\n" \
|
|
" .align 3\n" \
|
|
" .long 1b, 4b\n" \
|
|
" .long 2b, 4b\n" \
|
|
" .popsection" \
|
|
: "+r" (err), "+r" (__pu_addr) \
|
|
: "r" (x), "i" (-EFAULT) \
|
|
: "cc")
|
|
|
|
#endif /* !CONFIG_CPU_SPECTRE */
|
|
|
|
#ifdef CONFIG_MMU
|
|
extern unsigned long __must_check
|
|
arm_copy_from_user(void *to, const void __user *from, unsigned long n);
|
|
|
|
static inline unsigned long __must_check
|
|
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
unsigned int __ua_flags;
|
|
|
|
__ua_flags = uaccess_save_and_enable();
|
|
n = arm_copy_from_user(to, from, n);
|
|
uaccess_restore(__ua_flags);
|
|
return n;
|
|
}
|
|
|
|
extern unsigned long __must_check
|
|
arm_copy_to_user(void __user *to, const void *from, unsigned long n);
|
|
extern unsigned long __must_check
|
|
__copy_to_user_std(void __user *to, const void *from, unsigned long n);
|
|
|
|
static inline unsigned long __must_check
|
|
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
#ifndef CONFIG_UACCESS_WITH_MEMCPY
|
|
unsigned int __ua_flags;
|
|
__ua_flags = uaccess_save_and_enable();
|
|
n = arm_copy_to_user(to, from, n);
|
|
uaccess_restore(__ua_flags);
|
|
return n;
|
|
#else
|
|
return arm_copy_to_user(to, from, n);
|
|
#endif
|
|
}
|
|
|
|
extern unsigned long __must_check
|
|
arm_clear_user(void __user *addr, unsigned long n);
|
|
extern unsigned long __must_check
|
|
__clear_user_std(void __user *addr, unsigned long n);
|
|
|
|
static inline unsigned long __must_check
|
|
__clear_user(void __user *addr, unsigned long n)
|
|
{
|
|
unsigned int __ua_flags = uaccess_save_and_enable();
|
|
n = arm_clear_user(addr, n);
|
|
uaccess_restore(__ua_flags);
|
|
return n;
|
|
}
|
|
|
|
#else
|
|
static inline unsigned long
|
|
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
memcpy(to, (const void __force *)from, n);
|
|
return 0;
|
|
}
|
|
static inline unsigned long
|
|
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
memcpy((void __force *)to, from, n);
|
|
return 0;
|
|
}
|
|
#define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
|
|
#endif
|
|
#define INLINE_COPY_TO_USER
|
|
#define INLINE_COPY_FROM_USER
|
|
|
|
static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
|
|
{
|
|
if (access_ok(to, n))
|
|
n = __clear_user(to, n);
|
|
return n;
|
|
}
|
|
|
|
/* These are from lib/ code, and use __get_user() and friends */
|
|
extern long strncpy_from_user(char *dest, const char __user *src, long count);
|
|
|
|
extern __must_check long strnlen_user(const char __user *str, long n);
|
|
|
|
#endif /* _ASMARM_UACCESS_H */
|