leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

uaccess: generalize access_ok()

Browse Source 
There are many different ways that access_ok() is defined across
architectures, but in the end, they all just compare against the
user_addr_max() value or they accept anything.

Provide one definition that works for most architectures, checking
against TASK_SIZE_MAX for user processes or skipping the check inside
of uaccess_kernel() sections.

For architectures without CONFIG_SET_FS(), this should be the fastest
check, as it comes down to a single comparison of a pointer against a
compile-time constant, while the architecture specific versions tend to
do something more complex for historic reasons or get something wrong.

Type checking for __user annotations is handled inconsistently across
architectures, but this is easily simplified as well by using an inline
function that takes a 'const void __user *' argument. A handful of
callers need an extra __user annotation for this.

Some architectures had trick to use 33-bit or 65-bit arithmetic on the
addresses to calculate the overflow, however this simpler version uses
fewer registers, which means it can produce better object code in the
end despite needing a second (statically predicted) branch.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mark Rutland <mark.rutland@arm.com> [arm64, asm-generic]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Stafford Horne <shorne@gmail.com>
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Arnd Bergmann 2022-02-15 17:55:04 +01:00
parent 23fc539e81
commit 12700c17fc
32 changed files with 110 additions and 362 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/Kconfig
View File

@ -898,6 +898,13 @@ config HAVE_SOFTIRQ_ON_OWN_STACK
Architecture provides a function to run __do_softirq() on a
separate stack.
config ALTERNATE_USER_ADDRESS_SPACE
bool
help
Architectures set this when the CPU uses separate address
spaces for kernel and user space pointers. In this case, the
access_ok() check on a __user pointer is skipped.
config PGTABLE_LEVELS
int
default 2

34
arch/alpha/include/asm/uaccess.h
View File

@ -20,28 +20,7 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
/*
* Is a address valid? This does a straightforward calculation rather
* than tests.
*
* Address valid if:
* - "addr" doesn't have any high-bits set
* - AND "size" doesn't have any high-bits set
* - AND "addr+size-(size != 0)" doesn't have any high-bits set
* - OR we are in kernel mode.
*/
#define __access_ok(addr, size) ({ \
unsigned long __ao_a = (addr), __ao_b = (size); \
unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \
(get_fs().seg & (__ao_a | __ao_b | __ao_end)) == 0; })
#define access_ok(addr, size) \
({ \
__chk_user_ptr(addr); \
__access_ok(((unsigned long)(addr)), (size)); \
})
#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They automatically
@ -105,7 +84,7 @@ extern void __get_user_unknown(void);
long __gu_err = -EFAULT; \
unsigned long __gu_val = 0; \
const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \
if (__access_ok((unsigned long)__gu_addr, size)) { \
if (__access_ok(__gu_addr, size)) { \
__gu_err = 0; \
switch (size) { \
case 1: __get_user_8(__gu_addr); break; \
@ -200,7 +179,7 @@ extern void __put_user_unknown(void);
({ \
long __pu_err = -EFAULT; \
__typeof__(*(ptr)) __user *__pu_addr = (ptr); \
if (__access_ok((unsigned long)__pu_addr, size)) { \
if (__access_ok(__pu_addr, size)) { \
__pu_err = 0; \
switch (size) { \
case 1: __put_user_8(x, __pu_addr); break; \
@ -316,17 +295,14 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long len)
extern long __clear_user(void __user *to, long len);
extern inline long
static inline long
clear_user(void __user *to, long len)
{
if (__access_ok((unsigned long)to, len))
if (__access_ok(to, len))
len = __clear_user(to, len);
return len;
}
#define user_addr_max() \
(uaccess_kernel() ? ~0UL : TASK_SIZE)
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);

29
arch/arc/include/asm/uaccess.h
View File

@ -23,35 +23,6 @@
#include <linux/string.h> /* for generic string functions */
#define __kernel_ok (uaccess_kernel())
/*
* Algorithmically, for __user_ok() we want do:
* (start < TASK_SIZE) && (start+len < TASK_SIZE)
* where TASK_SIZE could either be retrieved from thread_info->addr_limit or
* emitted directly in code.
*
* This can however be rewritten as follows:
* (len <= TASK_SIZE) && (start+len < TASK_SIZE)
*
* Because it essentially checks if buffer end is within limit and @len is
* non-ngeative, which implies that buffer start will be within limit too.
*
* The reason for rewriting being, for majority of cases, @len is generally
* compile time constant, causing first sub-expression to be compile time
* subsumed.
*
* The second part would generate weird large LIMMs e.g. (0x6000_0000 - 0x10),
* so we check for TASK_SIZE using get_fs() since the addr_limit load from mem
* would already have been done at this call site for __kernel_ok()
*
*/
#define __user_ok(addr, sz) (((sz) <= TASK_SIZE) && \
((addr) <= (get_fs() - (sz))))
#define __access_ok(addr, sz) (unlikely(__kernel_ok) || \
likely(__user_ok((addr), (sz))))
/*********** Single byte/hword/word copies ******************/
#define __get_user_fn(sz, u, k) \

20
arch/arm/include/asm/uaccess.h
View File

@ -55,21 +55,6 @@ extern int __put_user_bad(void);
#ifdef CONFIG_MMU
/*
* 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" (TASK_SIZE) \
: "cc"); \
flag; })
/*
* This is a type: either unsigned long, if the argument fits into
* that type, or otherwise unsigned long long.
@ -241,15 +226,12 @@ extern int __put_user_8(void *, unsigned long long);
#else /* CONFIG_MMU */
#define __addr_ok(addr) ((void)(addr), 1)
#define __range_ok(addr, size) ((void)(addr), 0)
#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)
#include <asm-generic/access_ok.h>
#ifdef CONFIG_CPU_SPECTRE
/*

11
arch/arm64/include/asm/uaccess.h
View File

@ -26,13 +26,7 @@
#include <asm/memory.h>
#include <asm/extable.h>
static inline int __access_ok(const void __user *ptr, unsigned long size)
{
unsigned long limit = TASK_SIZE_MAX;
unsigned long addr = (unsigned long)ptr;
return (size <= limit) && (addr <= (limit - size));
}
static inline int __access_ok(const void __user *ptr, unsigned long size);
/*
* Test whether a block of memory is a valid user space address.
@ -54,6 +48,9 @@ static inline int access_ok(const void __user *addr, unsigned long size)
return likely(__access_ok(addr, size));
}
#define access_ok access_ok
#include <asm-generic/access_ok.h>
/*
* User access enabling/disabling.

8
arch/csky/include/asm/uaccess.h
View File

@ -5,14 +5,6 @@
#define user_addr_max() (current_thread_info()->addr_limit.seg)
static inline int __access_ok(unsigned long addr, unsigned long size)
{
unsigned long limit = user_addr_max();
return (size <= limit) && (addr <= (limit - size));
}
#define __access_ok __access_ok
/*
* __put_user_fn
*/

25
arch/hexagon/include/asm/uaccess.h
View File

@ -12,31 +12,6 @@
*/
#include <asm/sections.h>
/*
* access_ok: - Checks if a user space pointer is valid
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
* Returns true (nonzero) if the memory block *may* be valid, false (zero)
* if it is definitely invalid.
*
*/
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
static inline int __access_ok(unsigned long addr, unsigned long size)
{
unsigned long limit = TASK_SIZE;
return (size <= limit) && (addr <= (limit - size));
}
#define __access_ok __access_ok
/*
* When a kernel-mode page fault is taken, the faulting instruction
* address is checked against a table of exception_table_entries.

5
arch/ia64/include/asm/uaccess.h
View File

@ -50,8 +50,6 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(x) (current_thread_info()->addr_limit = (x))
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
/*
* When accessing user memory, we need to make sure the entire area really is in
* user-level space. In order to do this efficiently, we make sure that the page at
@ -65,7 +63,8 @@ static inline int __access_ok(const void __user *p, unsigned long size)
return likely(addr <= seg) &&
(seg == KERNEL_DS.seg || likely(REGION_OFFSET(addr) < RGN_MAP_LIMIT));
}
#define access_ok(addr, size) __access_ok((addr), (size))
#define __access_ok __access_ok
#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They automatically

1
arch/m68k/Kconfig.cpu
View File

@ -453,6 +453,7 @@ config CPU_HAS_NO_UNALIGNED
config CPU_HAS_ADDRESS_SPACES
bool
select ALTERNATE_USER_ADDRESS_SPACE
config FPU
bool

15
arch/m68k/include/asm/uaccess.h
View File

@ -10,20 +10,7 @@
#include <linux/compiler.h>
#include <linux/types.h>
#include <asm/extable.h>
/* We let the MMU do all checking */
static inline int access_ok(const void __user *ptr,
unsigned long size)
{
unsigned long limit = TASK_SIZE;
unsigned long addr = (unsigned long)ptr;
if (IS_ENABLED(CONFIG_CPU_HAS_ADDRESS_SPACES) ||
!IS_ENABLED(CONFIG_MMU))
return 1;
return (size <= limit) && (addr <= (limit - size));
}
#include <asm-generic/access_ok.h>
/*
* Not all varients of the 68k family support the notion of address spaces.

8
arch/microblaze/include/asm/uaccess.h
View File

@ -39,13 +39,7 @@
# define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
static inline int __access_ok(unsigned long addr, unsigned long size)
{
unsigned long limit = user_addr_max();
return (size <= limit) && (addr <= (limit - size));
}
#define access_ok(addr, size) __access_ok((unsigned long)addr, size)
#include <asm-generic/access_ok.h>
# define __FIXUP_SECTION ".section .fixup,\"ax\"\n"
# define __EX_TABLE_SECTION ".section __ex_table,\"a\"\n"

29
arch/mips/include/asm/uaccess.h
View File

@ -44,34 +44,7 @@ extern u64 __ua_limit;
#endif /* CONFIG_64BIT */
/*
* access_ok: - Checks if a user space pointer is valid
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
* Context: User context only. This function may sleep if pagefaults are
* enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
* Returns true (nonzero) if the memory block may be valid, false (zero)
* if it is definitely invalid.
*
* Note that, depending on architecture, this function probably just
* checks that the pointer is in the user space range - after calling
* this function, memory access functions may still return -EFAULT.
*/
static inline int __access_ok(const void __user *p, unsigned long size)
{
unsigned long addr = (unsigned long)p;
unsigned long limit = TASK_SIZE_MAX;
return (size <= limit) && (addr <= (limit - size));
}
#define access_ok(addr, size) \
likely(__access_ok((addr), (size)))
#include <asm-generic/access_ok.h>
/*
* put_user: - Write a simple value into user space.

7
arch/nds32/include/asm/uaccess.h
View File

@ -38,18 +38,15 @@ extern int fixup_exception(struct pt_regs *regs);
#define get_fs() (current_thread_info()->addr_limit)
#define user_addr_max get_fs
#define uaccess_kernel() (get_fs() == KERNEL_DS)
static inline void set_fs(mm_segment_t fs)
{
current_thread_info()->addr_limit = fs;
}
#define uaccess_kernel() (get_fs() == KERNEL_DS)
#include <asm-generic/access_ok.h>
#define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs() -size))
#define access_ok(addr, size) \
__range_ok((unsigned long)addr, (unsigned long)size)
/*
* Single-value transfer routines. They automatically use the right
* size if we just have the right pointer type. Note that the functions

11
arch/nios2/include/asm/uaccess.h
View File

@ -30,19 +30,10 @@
#define get_fs() (current_thread_info()->addr_limit)
#define set_fs(seg) (current_thread_info()->addr_limit = (seg))
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#define __access_ok(addr, len) \
(((signed long)(((long)get_fs().seg) & \
((long)(addr) | (((long)(addr)) + (len)) | (len)))) == 0)
#define access_ok(addr, len) \
likely(__access_ok((unsigned long)(addr), (unsigned long)(len)))
#include <asm-generic/access_ok.h>
# define __EX_TABLE_SECTION ".section __ex_table,\"a\"\n"
#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
/*
* Zero Userspace
*/

19
arch/openrisc/include/asm/uaccess.h
View File

@ -45,21 +45,7 @@
#define uaccess_kernel() (get_fs() == KERNEL_DS)
/* Ensure that the range from addr to addr+size is all within the process'
* address space
*/
static inline int __range_ok(unsigned long addr, unsigned long size)
{
const mm_segment_t fs = get_fs();
return size <= fs && addr <= (fs - size);
}
#define access_ok(addr, size) \
({ \
__chk_user_ptr(addr); \
__range_ok((unsigned long)(addr), (size)); \
})
#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They automatically
@ -268,9 +254,6 @@ clear_user(void __user *addr, unsigned long size)
return size;
}
#define user_addr_max() \
(uaccess_kernel() ? ~0UL : TASK_SIZE)
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);

1
arch/parisc/Kconfig
View File

@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
config PARISC
def_bool y
select ALTERNATE_USER_ADDRESS_SPACE
select ARCH_32BIT_OFF_T if !64BIT
select ARCH_MIGHT_HAVE_PC_PARPORT
select HAVE_FUNCTION_TRACER

12
arch/parisc/include/asm/uaccess.h
View File

@ -11,15 +11,9 @@
#include <linux/bug.h>
#include <linux/string.h>
/*
* Note that since kernel addresses are in a separate address space on
* parisc, we don't need to do anything for access_ok().
* We just let the page fault handler do the right thing. This also means
* that put_user is the same as __put_user, etc.
*/
#define access_ok(uaddr, size) \
( (uaddr) == (uaddr) )
#define TASK_SIZE_MAX DEFAULT_TASK_SIZE
#include <asm/pgtable.h>
#include <asm-generic/access_ok.h>
#define put_user __put_user
#define get_user __get_user

11
arch/powerpc/include/asm/uaccess.h
View File

@ -11,18 +11,9 @@
#ifdef __powerpc64__
/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
#define TASK_SIZE_MAX TASK_SIZE_USER64
#else
#define TASK_SIZE_MAX TASK_SIZE
#endif
static inline bool __access_ok(unsigned long addr, unsigned long size)
{
return addr < TASK_SIZE_MAX && size <= TASK_SIZE_MAX - addr;
}
#define access_ok(addr, size) \
(__chk_user_ptr(addr), \
__access_ok((unsigned long)(addr), (size)))
#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They automatically

31
arch/riscv/include/asm/uaccess.h
View File

@ -21,42 +21,13 @@
#include <asm/byteorder.h>
#include <asm/extable.h>
#include <asm/asm.h>
#include <asm-generic/access_ok.h>
#define __enable_user_access() \
__asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory")
#define __disable_user_access() \
__asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory")
/**
* access_ok: - Checks if a user space pointer is valid
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
* Context: User context only. This function may sleep.
*
* Checks if a pointer to a block of memory in user space is valid.
*
* Returns true (nonzero) if the memory block may be valid, false (zero)
* if it is definitely invalid.
*
* Note that, depending on architecture, this function probably just
* checks that the pointer is in the user space range - after calling
* this function, memory access functions may still return -EFAULT.
*/
#define access_ok(addr, size) ({ \
__chk_user_ptr(addr); \
likely(__access_ok((unsigned long __force)(addr), (size))); \
})
/*
* Ensure that the range [addr, addr+size) is within the process's
* address space
*/
static inline int __access_ok(unsigned long addr, unsigned long size)
{
return size <= TASK_SIZE && addr <= TASK_SIZE - size;
}
/*
* 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

1
arch/s390/Kconfig
View File

@ -55,6 +55,7 @@ config S390
# Note: keep this list sorted alphabetically
#
imply IMA_SECURE_AND_OR_TRUSTED_BOOT
select ALTERNATE_USER_ADDRESS_SPACE
select ARCH_32BIT_USTAT_F_TINODE
select ARCH_BINFMT_ELF_STATE
select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM

14
arch/s390/include/asm/uaccess.h
View File

@ -17,22 +17,10 @@
#include <asm/ctl_reg.h>
#include <asm/extable.h>
#include <asm/facility.h>
#include <asm-generic/access_ok.h>
void debug_user_asce(int exit);
static inline int __range_ok(unsigned long addr, unsigned long size)
{
return 1;
}
#define __access_ok(addr, size) \
({ \
__chk_user_ptr(addr); \
__range_ok((unsigned long)(addr), (size)); \
})
#define access_ok(addr, size) __access_ok(addr, size)
unsigned long __must_check
raw_copy_from_user(void *to, const void __user *from, unsigned long n);

22
arch/sh/include/asm/uaccess.h
View File

@ -5,28 +5,10 @@
#include <asm/segment.h>
#include <asm/extable.h>
#define __addr_ok(addr) \
((unsigned long __force)(addr) < current_thread_info()->addr_limit.seg)
/*
* __access_ok: Check if address with size is OK or not.
*
* Uhhuh, this needs 33-bit arithmetic. We have a carry..
*
* sum := addr + size; carry? --> flag = true;
* if (sum >= addr_limit) flag = true;
*/
#define __access_ok(addr, size) ({ \
unsigned long __ao_a = (addr), __ao_b = (size); \
unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \
__ao_end >= __ao_a && __addr_ok(__ao_end); })
#define access_ok(addr, size) \
(__chk_user_ptr(addr), \
__access_ok((unsigned long __force)(addr), (size)))
#define user_addr_max() (current_thread_info()->addr_limit.seg)
#include <asm-generic/access_ok.h>
/*
* Uh, these should become the main single-value transfer routines ...
* They automatically use the right size if we just have the right

1
arch/sparc/Kconfig
View File

@ -62,6 +62,7 @@ config SPARC32
config SPARC64
def_bool 64BIT
select ALTERNATE_USER_ADDRESS_SPACE
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_KRETPROBES

3
arch/sparc/include/asm/uaccess.h
View File

@ -10,9 +10,6 @@
#include <asm/uaccess_32.h>
#endif
#define user_addr_max() \
(uaccess_kernel() ? ~0UL : TASK_SIZE)
long strncpy_from_user(char *dest, const char __user *src, long count);
#endif

18
arch/sparc/include/asm/uaccess_32.h
View File

@ -25,17 +25,7 @@
#define get_fs() (current->thread.current_ds)
#define set_fs(val) ((current->thread.current_ds) = (val))
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
/* We have there a nice not-mapped page at PAGE_OFFSET - PAGE_SIZE, so that this test
* can be fairly lightweight.
* No one can read/write anything from userland in the kernel space by setting
* large size and address near to PAGE_OFFSET - a fault will break his intentions.
*/
#define __user_ok(addr, size) ({ (void)(size); (addr) < STACK_TOP; })
#define __kernel_ok (uaccess_kernel())
#define __access_ok(addr, size) (__user_ok((addr) & get_fs().seg, (size)))
#define access_ok(addr, size) __access_ok((unsigned long)(addr), size)
#include <asm-generic/access_ok.h>
/* Uh, these should become the main single-value transfer routines..
* They automatically use the right size if we just have the right
@ -47,13 +37,13 @@
* and hide all the ugliness from the user.
*/
#define put_user(x, ptr) ({ \
unsigned long __pu_addr = (unsigned long)(ptr); \
void __user *__pu_addr = (ptr); \
__chk_user_ptr(ptr); \
__put_user_check((__typeof__(*(ptr)))(x), __pu_addr, sizeof(*(ptr))); \
})
#define get_user(x, ptr) ({ \
unsigned long __gu_addr = (unsigned long)(ptr); \
const void __user *__gu_addr = (ptr); \
__chk_user_ptr(ptr); \
__get_user_check((x), __gu_addr, sizeof(*(ptr)), __typeof__(*(ptr))); \
})
@ -232,7 +222,7 @@ static inline unsigned long __clear_user(void __user *addr, unsigned long size)
static inline unsigned long clear_user(void __user *addr, unsigned long n)
{
if (n && __access_ok((unsigned long) addr, n))
if (n && __access_ok(addr, n))
return __clear_user(addr, n);
else
return n;

12
arch/sparc/include/asm/uaccess_64.h
View File

@ -31,7 +31,7 @@
#define get_fs() ((mm_segment_t){(current_thread_info()->current_ds)})
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#include <asm-generic/access_ok.h>
#define set_fs(val) \
do { \
@ -61,16 +61,6 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
__chk_range_not_ok((unsigned long __force)(addr), size, limit); \
})
static inline int __access_ok(const void __user * addr, unsigned long size)
{
return 1;
}
static inline int access_ok(const void __user * addr, unsigned long size)
{
return 1;
}
void __retl_efault(void);
/* Uh, these should become the main single-value transfer routines..

5
arch/um/include/asm/uaccess.h
View File

@ -25,7 +25,7 @@
extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n);
extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n);
extern unsigned long __clear_user(void __user *mem, unsigned long len);
static inline int __access_ok(unsigned long addr, unsigned long size);
static inline int __access_ok(const void __user *ptr, unsigned long size);
/* Teach asm-generic/uaccess.h that we have C functions for these. */
#define __access_ok __access_ok
@ -36,8 +36,9 @@ static inline int __access_ok(unsigned long addr, unsigned long size);
#include <asm-generic/uaccess.h>
static inline int __access_ok(unsigned long addr, unsigned long size)
static inline int __access_ok(const void __user *ptr, unsigned long size)
{
unsigned long addr = (unsigned long)ptr;
return __addr_range_nowrap(addr, size) &&
(__under_task_size(addr, size) ||
__access_ok_vsyscall(addr, size));

14
arch/x86/include/asm/uaccess.h
View File

@ -12,18 +12,6 @@
#include <asm/smap.h>
#include <asm/extable.h>
/*
* Test whether a block of memory is a valid user space address.
* Returns 0 if the range is valid, nonzero otherwise.
*/
static inline bool __access_ok(void __user *ptr, unsigned long size)
{
unsigned long limit = TASK_SIZE_MAX;
unsigned long addr = ptr;
return (size <= limit) && (addr <= (limit - size));
}
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
static inline bool pagefault_disabled(void);
# define WARN_ON_IN_IRQ() \
@ -55,6 +43,8 @@ static inline bool pagefault_disabled(void);
likely(__access_ok(addr, size)); \
})
#include <asm-generic/access_ok.h>
extern int __get_user_1(void);
extern int __get_user_2(void);
extern int __get_user_4(void);

10
arch/xtensa/include/asm/uaccess.h
View File

@ -35,15 +35,7 @@
#define get_fs() (current->thread.current_ds)
#define set_fs(val) (current->thread.current_ds = (val))
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#define __kernel_ok (uaccess_kernel())
#define __user_ok(addr, size) \
(((size) <= TASK_SIZE)&&((addr) <= TASK_SIZE-(size)))
#define __access_ok(addr, size) (__kernel_ok || __user_ok((addr), (size)))
#define access_ok(addr, size) __access_ok((unsigned long)(addr), (size))
#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They

60
include/asm-generic/access_ok.h Normal file
View File

@ -0,0 +1,60 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_GENERIC_ACCESS_OK_H__
#define __ASM_GENERIC_ACCESS_OK_H__
/*
* Checking whether a pointer is valid for user space access.
* These definitions work on most architectures, but overrides can
* be used where necessary.
*/
/*
* architectures with compat tasks have a variable TASK_SIZE and should
* override this to a constant.
*/
#ifndef TASK_SIZE_MAX
#define TASK_SIZE_MAX TASK_SIZE
#endif
#ifndef uaccess_kernel
#ifdef CONFIG_SET_FS
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#else
#define uaccess_kernel() (0)
#endif
#endif
#ifndef user_addr_max
#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE_MAX)
#endif
#ifndef __access_ok
/*
* 'size' is a compile-time constant for most callers, so optimize for
* this case to turn the check into a single comparison against a constant
* limit and catch all possible overflows.
* On architectures with separate user address space (m68k, s390, parisc,
* sparc64) or those without an MMU, this should always return true.
*
* This version was originally contributed by Jonas Bonn for the
* OpenRISC architecture, and was found to be the most efficient
* for constant 'size' and 'limit' values.
*/
static inline int __access_ok(const void __user *ptr, unsigned long size)
{
unsigned long limit = user_addr_max();
unsigned long addr = (unsigned long)ptr;
if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||
!IS_ENABLED(CONFIG_MMU))
return true;
return (size <= limit) && (addr <= (limit - size));
}
#endif
#ifndef access_ok
#define access_ok(addr, size) likely(__access_ok(addr, size))
#endif
#endif

21
include/asm-generic/uaccess.h
View File

@ -114,28 +114,9 @@ static inline void set_fs(mm_segment_t fs)
}
#endif
#ifndef uaccess_kernel
#define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
#endif
#ifndef user_addr_max
#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
#endif
#endif /* CONFIG_SET_FS */
#define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
/*
* The architecture should really override this if possible, at least
* doing a check on the get_fs()
*/
#ifndef __access_ok
static inline int __access_ok(unsigned long addr, unsigned long size)
{
return 1;
}
#endif
#include <asm-generic/access_ok.h>
/*
* These are the main single-value transfer routines. They automatically

7
include/linux/uaccess.h
View File

@ -33,13 +33,6 @@ typedef struct {
/* empty dummy */
} mm_segment_t;
#ifndef TASK_SIZE_MAX
#define TASK_SIZE_MAX TASK_SIZE
#endif
#define uaccess_kernel() (false)
#define user_addr_max() (TASK_SIZE_MAX)
static inline mm_segment_t force_uaccess_begin(void)
{
return (mm_segment_t) { };