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cfi: Switch to -fsanitize=kcfi

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Switch from Clang's original forward-edge control-flow integrity
implementation to -fsanitize=kcfi, which is better suited for the
kernel, as it doesn't require LTO, doesn't use a jump table that
requires altering function references, and won't break cross-module
function address equality.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-6-samitolvanen@google.com
This commit is contained in:
Sami Tolvanen 2022-09-08 14:54:47 -07:00 • committed by Kees Cook
parent 92efda8eb1
commit 8924560094
9 changed files with 139 additions and 182 deletions
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37
include/asm-generic/vmlinux.lds.h
View file

@ -421,6 +421,22 @@
__end_ro_after_init = .;
#endif
/*
* .kcfi_traps contains a list KCFI trap locations.
*/
#ifndef KCFI_TRAPS
#ifdef CONFIG_ARCH_USES_CFI_TRAPS
#define KCFI_TRAPS \
__kcfi_traps : AT(ADDR(__kcfi_traps) - LOAD_OFFSET) { \
__start___kcfi_traps = .; \
KEEP(*(.kcfi_traps)) \
__stop___kcfi_traps = .; \
}
#else
#define KCFI_TRAPS
#endif
#endif
/*
* Read only Data
*/
@ -529,6 +545,8 @@
__stop___modver = .; \
} \
\
KCFI_TRAPS \
\
RO_EXCEPTION_TABLE \
NOTES \
BTF \
@ -537,21 +555,6 @@
__end_rodata = .;
/*
* .text..L.cfi.jumptable.* contain Control-Flow Integrity (CFI)
* jump table entries.
*/
#ifdef CONFIG_CFI_CLANG
#define TEXT_CFI_JT \
. = ALIGN(PMD_SIZE); \
__cfi_jt_start = .; \
*(.text..L.cfi.jumptable .text..L.cfi.jumptable.*) \
. = ALIGN(PMD_SIZE); \
__cfi_jt_end = .;
#else
#define TEXT_CFI_JT
#endif
/*
* Non-instrumentable text section
*/
@ -579,7 +582,6 @@
*(.text..refcount) \
*(.ref.text) \
*(.text.asan.* .text.tsan.*) \
TEXT_CFI_JT \
MEM_KEEP(init.text*) \
MEM_KEEP(exit.text*) \
@ -1008,8 +1010,7 @@
* keep any .init_array.* sections.
* https://bugs.llvm.org/show_bug.cgi?id=46478
*/
#if defined(CONFIG_GCOV_KERNEL) || defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN) || \
defined(CONFIG_CFI_CLANG)
#if defined(CONFIG_GCOV_KERNEL) || defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN)
# ifdef CONFIG_CONSTRUCTORS
# define SANITIZER_DISCARDS \
*(.eh_frame)