From: Christoph Hellwig <hch@xxxxxx> Subject: x86: use non-set_fs based maccess routines Provide arch_kernel_read and arch_kernel_write routines to implement the maccess routines without messing with set_fs and without stac/clac that opens up access to user space. [akpm@xxxxxxxxxxxxxxxxxxxx: coding style fixes] Link: http://lkml.kernel.org/r/20200521152301.2587579-20-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/include/asm/uaccess.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) --- a/arch/x86/include/asm/uaccess.h~x86-use-non-set_fs-based-maccess-routines +++ a/arch/x86/include/asm/uaccess.h @@ -523,5 +523,21 @@ do { \ unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ } while (0) +#define HAVE_GET_KERNEL_NOFAULT + +#define __get_kernel_nofault(dst, src, type, err_label) \ +do { \ + int __kr_err; \ + \ + __get_user_size(*((type *)dst), (__force type __user *)src, \ + sizeof(type), __kr_err); \ + if (unlikely(__kr_err)) \ + goto err_label; \ +} while (0) + +#define __put_kernel_nofault(dst, src, type, err_label) \ + __put_user_size(*((type *)(src)), (__force type __user *)(dst), \ + sizeof(type), err_label) + #endif /* _ASM_X86_UACCESS_H */ _
