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
..
bugs.c	lkdtm: Check for SMEP clearing protections	2019-06-23 07:05:56 +02:00
core.c	lkdtm: Check for SMEP clearing protections	2019-06-23 07:05:56 +02:00
heap.c
lkdtm.h	lkdtm: Check for SMEP clearing protections	2019-06-23 07:05:56 +02:00
Makefile	lkdtm: support llvm-objcopy	2019-05-24 20:42:50 +02:00
perms.c	lkdtm: Add tests for NULL pointer dereference	2019-01-09 12:00:31 -08:00
refcount.c
rodata.c
stackleak.c	lkdtm: Add a test for STACKLEAK	2018-09-04 10:35:47 -07:00
usercopy.c	lkdtm/usercopy: Moves the KERNEL_DS test to non-canonical	2019-04-07 10:38:31 -07:00