Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | #include <linux/spinlock.h> |
| 2 | #include <linux/errno.h> |
| 3 | #include <linux/init.h> |
| 4 | |
| 5 | #include <asm/pgtable.h> |
| 6 | #include <asm/proto.h> |
| 7 | |
| 8 | static int disable_nx; |
| 9 | |
| 10 | /* |
| 11 | * noexec = on|off |
| 12 | * |
| 13 | * Control non-executable mappings for processes. |
| 14 | * |
| 15 | * on Enable |
| 16 | * off Disable |
| 17 | */ |
| 18 | static int __init noexec_setup(char *str) |
| 19 | { |
| 20 | if (!str) |
| 21 | return -EINVAL; |
| 22 | if (!strncmp(str, "on", 2)) { |
| 23 | disable_nx = 0; |
| 24 | } else if (!strncmp(str, "off", 3)) { |
| 25 | disable_nx = 1; |
| 26 | } |
| 27 | x86_configure_nx(); |
| 28 | return 0; |
| 29 | } |
| 30 | early_param("noexec", noexec_setup); |
| 31 | |
| 32 | void x86_configure_nx(void) |
| 33 | { |
| 34 | if (cpu_has_nx && !disable_nx) |
| 35 | __supported_pte_mask |= _PAGE_NX; |
| 36 | else |
| 37 | __supported_pte_mask &= ~_PAGE_NX; |
| 38 | } |
| 39 | |
| 40 | void __init x86_report_nx(void) |
| 41 | { |
| 42 | if (!cpu_has_nx) { |
| 43 | printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " |
| 44 | "missing in CPU!\n"); |
| 45 | } else { |
| 46 | #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) |
| 47 | if (disable_nx) { |
| 48 | printk(KERN_INFO "NX (Execute Disable) protection: " |
| 49 | "disabled by kernel command line option\n"); |
| 50 | } else { |
| 51 | printk(KERN_INFO "NX (Execute Disable) protection: " |
| 52 | "active\n"); |
| 53 | } |
| 54 | #else |
| 55 | /* 32bit non-PAE kernel, NX cannot be used */ |
| 56 | printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " |
| 57 | "cannot be enabled: non-PAE kernel!\n"); |
| 58 | #endif |
| 59 | } |
| 60 | } |