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