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/*
* arch/arm/include/asm/uaccess.h
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _ASMARM_UACCESS_H
#define _ASMARM_UACCESS_H
/*
* User space memory access functions
*/
#include <linux/string.h>
#include <linux/thread_info.h>
#include <asm/errno.h>
#include <asm/memory.h>
#include <asm/domain.h>
#include <asm/unified.h>
#include <asm/compiler.h>
#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
#include <asm-generic/uaccess-unaligned.h>
#else
#define __get_user_unaligned __get_user
#define __put_user_unaligned __put_user
#endif
#define VERIFY_READ 0
#define VERIFY_WRITE 1
/*
* The exception table consists of pairs of addresses: the first is the
* address of an instruction that is allowed to fault, and the second is
* the address at which the program should continue. No registers are
* modified, so it is entirely up to the continuation code to figure out
* what to do.
*
* All the routines below use bits of fixup code that are out of line
* with the main instruction path. This means when everything is well,
* we don't even have to jump over them. Further, they do not intrude
* on our cache or tlb entries.
*/
struct exception_table_entry
{
unsigned long insn, fixup;
};
extern int fixup_exception(struct pt_regs *regs);
/*
* 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 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 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
#define get_ds() (KERNEL_DS)
#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 segment_eq(a, b) ((a) == (b))
#define __addr_ok(addr) ({ \
unsigned long flag; \
__asm__("cmp %2, %0; movlo %0, #0" \
: "=&r" (flag) \
: "0" (current_thread_info()->addr_limit), "r" (addr) \
: "cc"); \
(flag == 0); })
/* We use 33-bit arithmetic here... */
#define __range_ok(addr, size) ({ \
unsigned long flag, roksum; \
__chk_user_ptr(addr); \
__asm__("adds %1, %2, %3; sbcccs %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(
" sub %1, %3, #1\n"
" subs %1, %1, %0\n"
" addhs %1, %1, #1\n"
" subhss %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 const 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 segment_eq(a, b) (1)
#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(type, addr, size) (__range_ok(addr, size) == 0)
#define user_addr_max() \
(segment_eq(get_fs(), KERNEL_DS) ? ~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
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
unsigned int __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
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
#ifndef CONFIG_UACCESS_WITH_MEMCPY
unsigned int __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
#define __copy_from_user(to, from, n) (memcpy(to, (void __force *)from, n), 0)
#define __copy_to_user(to, from, n) (memcpy((void __force *)to, from, n), 0)
#define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
#endif
static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (access_ok(VERIFY_READ, from, n))
n = __copy_from_user(to, from, n);
else /* security hole - plug it */
memset(to, 0, n);
return n;
}
static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
{
if (access_ok(VERIFY_WRITE, to, n))
n = __copy_to_user(to, from, n);
return n;
}
#define __copy_to_user_inatomic __copy_to_user
#define __copy_from_user_inatomic __copy_from_user
static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
{
if (access_ok(VERIFY_WRITE, 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 strlen_user(const char __user *str);
extern __must_check long strnlen_user(const char __user *str, long n);
#endif /* _ASMARM_UACCESS_H */
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