linux-stable/drivers/misc/lkdtm/lkdtm.h
Kees Cook 06b32fdb03 lkdtm: Check for SMEP clearing protections
This adds an x86-specific test for pinned cr4 bits. A successful test
will validate pinning and check the ROP-style call-middle-of-function
defense, if needed. For example, in the case of native_write_cr4()
looking like this:

ffffffff8171bce0 <native_write_cr4>:
ffffffff8171bce0:       48 8b 35 79 46 f2 00    mov    0xf24679(%rip),%rsi
ffffffff8171bce7:       48 09 f7                or     %rsi,%rdi
ffffffff8171bcea:       0f 22 e7                mov    %rdi,%cr4
...
ffffffff8171bd5a:       c3                      retq

The UNSET_SMEP test will jump to ffffffff8171bcea (the mov to cr4)
instead of ffffffff8171bce0 (native_write_cr4() entry) to simulate a
direct-call bypass attempt.

Expected successful results:

  # echo UNSET_SMEP > /sys/kernel/debug/provoke-crash/DIRECT
  # dmesg
  [   79.594433] lkdtm: Performing direct entry UNSET_SMEP
  [   79.596459] lkdtm: trying to clear SMEP normally
  [   79.598406] lkdtm: ok: SMEP did not get cleared
  [   79.599981] lkdtm: trying to clear SMEP with call gadget
  [   79.601810] ------------[ cut here ]------------
  [   79.603421] Attempt to unpin cr4 bits: 100000; bypass attack?!
  ...
  [   79.650170] ---[ end trace 2452ca0f6126242e ]---
  [   79.650937] lkdtm: ok: SMEP removal was reverted

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-23 07:05:56 +02:00

93 lines
2.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LKDTM_H
#define __LKDTM_H
#define pr_fmt(fmt) "lkdtm: " fmt
#include <linux/kernel.h>
/* lkdtm_bugs.c */
void __init lkdtm_bugs_init(int *recur_param);
void lkdtm_PANIC(void);
void lkdtm_BUG(void);
void lkdtm_WARNING(void);
void lkdtm_EXCEPTION(void);
void lkdtm_LOOP(void);
void lkdtm_EXHAUST_STACK(void);
void lkdtm_CORRUPT_STACK(void);
void lkdtm_CORRUPT_STACK_STRONG(void);
void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void);
void lkdtm_SOFTLOCKUP(void);
void lkdtm_HARDLOCKUP(void);
void lkdtm_SPINLOCKUP(void);
void lkdtm_HUNG_TASK(void);
void lkdtm_CORRUPT_LIST_ADD(void);
void lkdtm_CORRUPT_LIST_DEL(void);
void lkdtm_CORRUPT_USER_DS(void);
void lkdtm_STACK_GUARD_PAGE_LEADING(void);
void lkdtm_STACK_GUARD_PAGE_TRAILING(void);
void lkdtm_UNSET_SMEP(void);
/* lkdtm_heap.c */
void lkdtm_OVERWRITE_ALLOCATION(void);
void lkdtm_WRITE_AFTER_FREE(void);
void lkdtm_READ_AFTER_FREE(void);
void lkdtm_WRITE_BUDDY_AFTER_FREE(void);
void lkdtm_READ_BUDDY_AFTER_FREE(void);
/* lkdtm_perms.c */
void __init lkdtm_perms_init(void);
void lkdtm_WRITE_RO(void);
void lkdtm_WRITE_RO_AFTER_INIT(void);
void lkdtm_WRITE_KERN(void);
void lkdtm_EXEC_DATA(void);
void lkdtm_EXEC_STACK(void);
void lkdtm_EXEC_KMALLOC(void);
void lkdtm_EXEC_VMALLOC(void);
void lkdtm_EXEC_RODATA(void);
void lkdtm_EXEC_USERSPACE(void);
void lkdtm_EXEC_NULL(void);
void lkdtm_ACCESS_USERSPACE(void);
void lkdtm_ACCESS_NULL(void);
/* lkdtm_refcount.c */
void lkdtm_REFCOUNT_INC_OVERFLOW(void);
void lkdtm_REFCOUNT_ADD_OVERFLOW(void);
void lkdtm_REFCOUNT_INC_NOT_ZERO_OVERFLOW(void);
void lkdtm_REFCOUNT_ADD_NOT_ZERO_OVERFLOW(void);
void lkdtm_REFCOUNT_DEC_ZERO(void);
void lkdtm_REFCOUNT_DEC_NEGATIVE(void);
void lkdtm_REFCOUNT_DEC_AND_TEST_NEGATIVE(void);
void lkdtm_REFCOUNT_SUB_AND_TEST_NEGATIVE(void);
void lkdtm_REFCOUNT_INC_ZERO(void);
void lkdtm_REFCOUNT_ADD_ZERO(void);
void lkdtm_REFCOUNT_INC_SATURATED(void);
void lkdtm_REFCOUNT_DEC_SATURATED(void);
void lkdtm_REFCOUNT_ADD_SATURATED(void);
void lkdtm_REFCOUNT_INC_NOT_ZERO_SATURATED(void);
void lkdtm_REFCOUNT_ADD_NOT_ZERO_SATURATED(void);
void lkdtm_REFCOUNT_DEC_AND_TEST_SATURATED(void);
void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void);
void lkdtm_REFCOUNT_TIMING(void);
void lkdtm_ATOMIC_TIMING(void);
/* lkdtm_rodata.c */
void lkdtm_rodata_do_nothing(void);
/* lkdtm_usercopy.c */
void __init lkdtm_usercopy_init(void);
void __exit lkdtm_usercopy_exit(void);
void lkdtm_USERCOPY_HEAP_SIZE_TO(void);
void lkdtm_USERCOPY_HEAP_SIZE_FROM(void);
void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void);
void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void);
void lkdtm_USERCOPY_STACK_FRAME_TO(void);
void lkdtm_USERCOPY_STACK_FRAME_FROM(void);
void lkdtm_USERCOPY_STACK_BEYOND(void);
void lkdtm_USERCOPY_KERNEL(void);
void lkdtm_USERCOPY_KERNEL_DS(void);
/* lkdtm_stackleak.c */
void lkdtm_STACKLEAK_ERASING(void);
#endif