arch/x86/mm/maccess.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include <linux/uaccess.h>
   4 #include <linux/kernel.h>
   5
   6 #ifdef CONFIG_X86_64
   7 static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)
   8 {
   9         return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
  10 }
  11
  12 static __always_inline bool invalid_probe_range(u64 vaddr)
  13 {
  14         /*
  15          * Range covering the highest possible canonical userspace address
  16          * as well as non-canonical address range. For the canonical range
  17          * we also need to include the userspace guard page.
  18          */
  19         return vaddr < TASK_SIZE_MAX + PAGE_SIZE ||
  20                canonical_address(vaddr, boot_cpu_data.x86_virt_bits) != vaddr;
  21 }
  22 #else
  23 static __always_inline bool invalid_probe_range(u64 vaddr)
  24 {
  25         return vaddr < TASK_SIZE_MAX;
  26 }
  27 #endif
  28
  29 long probe_kernel_read_strict(void *dst, const void *src, size_t size)
  30 {
  31         if (unlikely(invalid_probe_range((unsigned long)src)))
  32                 return -EFAULT;
  33
  34         return __probe_kernel_read(dst, src, size);
  35 }
  36
  37 long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr, long count)
  38 {
  39         if (unlikely(invalid_probe_range((unsigned long)unsafe_addr)))
  40                 return -EFAULT;
  41
  42         return __strncpy_from_unsafe(dst, unsafe_addr, count);
  43 }