| Kees Cook | 8ab3820 | 2013-10-10 17:18:14 -0700 | [diff] [blame] | 1 | #include "misc.h" |
| 2 | |
| 3 | #ifdef CONFIG_RANDOMIZE_BASE |
| Kees Cook | 5bfce5e | 2013-10-10 17:18:15 -0700 | [diff] [blame^] | 4 | #include <asm/msr.h> |
| 5 | #include <asm/archrandom.h> |
| 6 | |
| 7 | #define I8254_PORT_CONTROL 0x43 |
| 8 | #define I8254_PORT_COUNTER0 0x40 |
| 9 | #define I8254_CMD_READBACK 0xC0 |
| 10 | #define I8254_SELECT_COUNTER0 0x02 |
| 11 | #define I8254_STATUS_NOTREADY 0x40 |
| 12 | static inline u16 i8254(void) |
| 13 | { |
| 14 | u16 status, timer; |
| 15 | |
| 16 | do { |
| 17 | outb(I8254_PORT_CONTROL, |
| 18 | I8254_CMD_READBACK | I8254_SELECT_COUNTER0); |
| 19 | status = inb(I8254_PORT_COUNTER0); |
| 20 | timer = inb(I8254_PORT_COUNTER0); |
| 21 | timer |= inb(I8254_PORT_COUNTER0) << 8; |
| 22 | } while (status & I8254_STATUS_NOTREADY); |
| 23 | |
| 24 | return timer; |
| 25 | } |
| 26 | |
| 27 | static unsigned long get_random_long(void) |
| 28 | { |
| 29 | unsigned long random; |
| 30 | |
| 31 | if (has_cpuflag(X86_FEATURE_RDRAND)) { |
| 32 | debug_putstr("KASLR using RDRAND...\n"); |
| 33 | if (rdrand_long(&random)) |
| 34 | return random; |
| 35 | } |
| 36 | |
| 37 | if (has_cpuflag(X86_FEATURE_TSC)) { |
| 38 | uint32_t raw; |
| 39 | |
| 40 | debug_putstr("KASLR using RDTSC...\n"); |
| 41 | rdtscl(raw); |
| 42 | |
| 43 | /* Only use the low bits of rdtsc. */ |
| 44 | random = raw & 0xffff; |
| 45 | } else { |
| 46 | debug_putstr("KASLR using i8254...\n"); |
| 47 | random = i8254(); |
| 48 | } |
| 49 | |
| 50 | /* Extend timer bits poorly... */ |
| 51 | random |= (random << 16); |
| 52 | #ifdef CONFIG_X86_64 |
| 53 | random |= (random << 32); |
| 54 | #endif |
| 55 | return random; |
| 56 | } |
| Kees Cook | 8ab3820 | 2013-10-10 17:18:14 -0700 | [diff] [blame] | 57 | |
| 58 | unsigned char *choose_kernel_location(unsigned char *input, |
| 59 | unsigned long input_size, |
| 60 | unsigned char *output, |
| 61 | unsigned long output_size) |
| 62 | { |
| 63 | unsigned long choice = (unsigned long)output; |
| 64 | |
| 65 | if (cmdline_find_option_bool("nokaslr")) { |
| 66 | debug_putstr("KASLR disabled...\n"); |
| 67 | goto out; |
| 68 | } |
| 69 | |
| 70 | /* XXX: choose random location. */ |
| 71 | |
| 72 | out: |
| 73 | return (unsigned char *)choice; |
| 74 | } |
| 75 | |
| 76 | #endif /* CONFIG_RANDOMIZE_BASE */ |