| 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 | bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) |
| 8 | { |
| 9 | unsigned long vaddr = (unsigned long)unsafe_src; |
| 10 | |
| 11 | /* |
| 12 | * Do not allow userspace addresses. This disallows |
| 13 | * normal userspace and the userspace guard page: |
| 14 | */ |
| 15 | if (vaddr < TASK_SIZE_MAX + PAGE_SIZE) |
| 16 | return false; |
| 17 | |
| 18 | /* |
| 19 | * Allow everything during early boot before 'x86_virt_bits' |
| 20 | * is initialized. Needed for instruction decoding in early |
| 21 | * exception handlers. |
| 22 | */ |
| 23 | if (!boot_cpu_data.x86_virt_bits) |
| 24 | return true; |
| 25 | |
| 26 | return __is_canonical_address(vaddr, vaddr_bits: boot_cpu_data.x86_virt_bits); |
| 27 | } |
| 28 | #else |
| 29 | bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) |
| 30 | { |
| 31 | return (unsigned long)unsafe_src >= TASK_SIZE_MAX; |
| 32 | } |
| 33 | #endif |
| 34 |