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uaccess: add generic __{get,put}_kernel_nofault

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Nine architectures are still missing __{get,put}_kernel_nofault:
alpha, ia64, microblaze, nds32, nios2, openrisc, sh, sparc32, xtensa.

Add a generic version that lets everything use the normal
copy_{from,to}_kernel_nofault() code based on these, removing the last
use of get_fs()/set_fs() from architecture-independent code.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Arnd Bergmann 2022-02-11 08:50:00 +01:00
parent 90997c1280
commit 34737e2698
14 changed files with 19 additions and 131 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
arch/arm/include/asm/uaccess.h
View file

@ -476,8 +476,6 @@ do { \
: "r" (x), "i" (-EFAULT) \
: "cc")
#define HAVE_GET_KERNEL_NOFAULT
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
const type *__pk_ptr = (src); \

2
arch/arm64/include/asm/uaccess.h
View file

@ -26,8 +26,6 @@
#include <asm/memory.h>
#include <asm/extable.h>
#define HAVE_GET_KERNEL_NOFAULT
/*
* Test whether a block of memory is a valid user space address.
* Returns 1 if the range is valid, 0 otherwise.

2
arch/m68k/include/asm/uaccess.h
View file

@ -390,8 +390,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
#define INLINE_COPY_FROM_USER
#define INLINE_COPY_TO_USER
#define HAVE_GET_KERNEL_NOFAULT
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
type *__gk_dst = (type *)(dst); \

2
arch/mips/include/asm/uaccess.h
View file

@ -296,8 +296,6 @@ struct __large_struct { unsigned long buf[100]; };
(val) = __gu_tmp.t; \
}
#define HAVE_GET_KERNEL_NOFAULT
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
int __gu_err; \

1
arch/parisc/include/asm/uaccess.h
View file

@ -95,7 +95,6 @@ struct exception_table_entry {
(val) = (__force __typeof__(*(ptr))) __gu_val; \
}
#define HAVE_GET_KERNEL_NOFAULT
#define __get_kernel_nofault(dst, src, type, err_label) \
{ \
type __z; \

2
arch/powerpc/include/asm/uaccess.h
View file

@ -467,8 +467,6 @@ do { \
unsafe_put_user(*(u8*)(_src + _i), (u8 __user *)(_dst + _i), e); \
} while (0)
#define HAVE_GET_KERNEL_NOFAULT
#define __get_kernel_nofault(dst, src, type, err_label) \
__get_user_size_goto(*((type *)(dst)), \
(__force type __user *)(src), sizeof(type), err_label)

2
arch/riscv/include/asm/uaccess.h
View file

@ -346,8 +346,6 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
__clear_user(to, n) : n;
}
#define HAVE_GET_KERNEL_NOFAULT
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
long __kr_err; \

2
arch/s390/include/asm/uaccess.h
View file

@ -282,8 +282,6 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo
int copy_to_user_real(void __user *dest, void *src, unsigned long count);
void *s390_kernel_write(void *dst, const void *src, size_t size);
#define HAVE_GET_KERNEL_NOFAULT
int __noreturn __put_kernel_bad(void);
#define __put_kernel_asm(val, to, insn) \

2
arch/sparc/include/asm/uaccess_64.h
View file

@ -210,8 +210,6 @@ __asm__ __volatile__( \
: "=r" (ret), "=r" (x) : "r" (__m(addr)), \
"i" (-EFAULT))
#define HAVE_GET_KERNEL_NOFAULT
#define __get_user_nocheck(data, addr, size, type) ({ \
register int __gu_ret; \
register unsigned long __gu_val; \

2
arch/um/include/asm/uaccess.h
View file

@ -44,8 +44,6 @@ static inline int __access_ok(unsigned long addr, unsigned long size)
}
/* no pagefaults for kernel addresses in um */
#define HAVE_GET_KERNEL_NOFAULT 1
#define __get_kernel_nofault(dst, src, type, err_label) \
do { \
*((type *)dst) = get_unaligned((type *)(src)); \

2
arch/x86/include/asm/uaccess.h
View file

@ -507,8 +507,6 @@ do { \
unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
} while (0)
#define HAVE_GET_KERNEL_NOFAULT
#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
#define __get_kernel_nofault(dst, src, type, err_label) \
__get_user_size(*((type *)(dst)), (__force type __user *)(src), \

2
include/asm-generic/uaccess.h
View file

@ -77,8 +77,6 @@ do { \
goto err_label; \
} while (0)
#define HAVE_GET_KERNEL_NOFAULT 1
static inline __must_check unsigned long
raw_copy_from_user(void *to, const void __user * from, unsigned long n)
{

19
include/linux/uaccess.h
View file

@ -368,6 +368,25 @@ long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
long count);
long strnlen_user_nofault(const void __user *unsafe_addr, long count);
#ifndef __get_kernel_nofault
#define __get_kernel_nofault(dst, src, type, label) \
do { \
type __user *p = (type __force __user *)(src); \
type data; \
if (__get_user(data, p)) \
goto label; \
*(type *)dst = data; \
} while (0)
#define __put_kernel_nofault(dst, src, type, label) \
do { \
type __user *p = (type __force __user *)(dst); \
type data = *(type *)src; \
if (__put_user(data, p)) \
goto label; \
} while (0)
#endif
/**
* get_kernel_nofault(): safely attempt to read from a location
* @val: read into this variable

108
mm/maccess.c
View file

@ -12,8 +12,6 @@ bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
return true;
}
#ifdef HAVE_GET_KERNEL_NOFAULT
#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \
while (len >= sizeof(type)) { \
__get_kernel_nofault(dst, src, type, err_label); \
@ -102,112 +100,6 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
dst[-1] = '\0';
return -EFAULT;
}
#else /* HAVE_GET_KERNEL_NOFAULT */
/**
* copy_from_kernel_nofault(): safely attempt to read from kernel-space
* @dst: pointer to the buffer that shall take the data
* @src: address to read from
* @size: size of the data chunk
*
* Safely read from kernel address @src to the buffer at @dst. If a kernel
* fault happens, handle that and return -EFAULT. If @src is not a valid kernel
* address, return -ERANGE.
*
* We ensure that the copy_from_user is executed in atomic context so that
* do_page_fault() doesn't attempt to take mmap_lock. This makes
* copy_from_kernel_nofault() suitable for use within regions where the caller
* already holds mmap_lock, or other locks which nest inside mmap_lock.
*/
long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
if (!copy_from_kernel_nofault_allowed(src, size))
return -ERANGE;
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
size);
pagefault_enable();
set_fs(old_fs);
if (ret)
return -EFAULT;
return 0;
}
EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
/**
* copy_to_kernel_nofault(): safely attempt to write to a location
* @dst: address to write to
* @src: pointer to the data that shall be written
* @size: size of the data chunk
*
* Safely write to address @dst from the buffer at @src. If a kernel fault
* happens, handle that and return -EFAULT.
*/
long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
{
long ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
pagefault_enable();
set_fs(old_fs);
if (ret)
return -EFAULT;
return 0;
}
/**
* strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
* address.
* @dst: Destination address, in kernel space. This buffer must be at
* least @count bytes long.
* @unsafe_addr: Unsafe address.
* @count: Maximum number of bytes to copy, including the trailing NUL.
*
* Copies a NUL-terminated string from unsafe address to kernel buffer.
*
* On success, returns the length of the string INCLUDING the trailing NUL.
*
* If access fails, returns -EFAULT (some data may have been copied and the
* trailing NUL added). If @unsafe_addr is not a valid kernel address, return
* -ERANGE.
*
* If @count is smaller than the length of the string, copies @count-1 bytes,
* sets the last byte of @dst buffer to NUL and returns @count.
*/
long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
{
mm_segment_t old_fs = get_fs();
const void *src = unsafe_addr;
long ret;
if (unlikely(count <= 0))
return 0;
if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
return -ERANGE;
set_fs(KERNEL_DS);
pagefault_disable();
do {
ret = __get_user(*dst++, (const char __user __force *)src++);
} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
dst[-1] = '\0';
pagefault_enable();
set_fs(old_fs);
return ret ? -EFAULT : src - unsafe_addr;
}
#endif /* HAVE_GET_KERNEL_NOFAULT */
/**
* copy_from_user_nofault(): safely attempt to read from a user-space location