Line data    Source code

       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          98 : static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)
       8             : {
       9          98 :         return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);
      10             : }
      11             : 
      12          98 : bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
      13             : {
      14          98 :         unsigned long vaddr = (unsigned long)unsafe_src;
      15             : 
      16             :         /*
      17             :          * Range covering the highest possible canonical userspace address
      18             :          * as well as non-canonical address range. For the canonical range
      19             :          * we also need to include the userspace guard page.
      20             :          */
      21          98 :         return vaddr >= TASK_SIZE_MAX + PAGE_SIZE &&
      22          98 :                canonical_address(vaddr, boot_cpu_data.x86_virt_bits) == vaddr;
      23             : }
      24             : #else
      25             : bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
      26             : {
      27             :         return (unsigned long)unsafe_src >= TASK_SIZE_MAX;
      28             : }
      29             : #endif