Commit ccace936 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Kees Cook
Browse files

x86: Add types to indirectly called assembly functions 



With CONFIG_CFI_CLANG, assembly functions indirectly called
from C code must be annotated with type identifiers to pass CFI
checking. Define the __CFI_TYPE helper macro to match the compiler
generated function preamble, and ensure SYM_TYPED_FUNC_START also
emits ENDBR with IBT.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Tested-by: default avatarKees Cook <keescook@chromium.org>
Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-21-samitolvanen@google.com
parent ca7e10bf

arch/x86/crypto/blowfish-x86_64-asm_64.S

+3 −2
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 */



#include <linux/linkage.h>

#include <linux/cfi_types.h>



.file "blowfish-x86_64-asm.S"

.text
@@ -141,7 +142,7 @@ SYM_FUNC_START(__blowfish_enc_blk) 
	RET;

SYM_FUNC_END(__blowfish_enc_blk)



SYM_FUNC_START(blowfish_dec_blk)

SYM_TYPED_FUNC_START(blowfish_dec_blk)

	/* input:

	 *	%rdi: ctx

	 *	%rsi: dst
@@ -332,7 +333,7 @@ SYM_FUNC_START(__blowfish_enc_blk_4way) 
	RET;

SYM_FUNC_END(__blowfish_enc_blk_4way)



SYM_FUNC_START(blowfish_dec_blk_4way)

SYM_TYPED_FUNC_START(blowfish_dec_blk_4way)

	/* input:

	 *	%rdi: ctx

	 *	%rsi: dst

arch/x86/include/asm/linkage.h

+12 −0
Original line number Diff line number Diff line
@@ -43,6 +43,18 @@ 


#endif /* __ASSEMBLY__ */



#define __CFI_TYPE(name)					\

	SYM_START(__cfi_##name, SYM_L_LOCAL, SYM_A_NONE)	\

	.fill 11, 1, 0x90 ASM_NL				\

	.byte 0xb8 ASM_NL					\

	.long __kcfi_typeid_##name ASM_NL			\

	SYM_FUNC_END(__cfi_##name)



/* SYM_TYPED_FUNC_START -- use for indirectly called globals, w/ CFI type */

#define SYM_TYPED_FUNC_START(name)				\

	SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)	\

	ENDBR



/* SYM_FUNC_START -- use for global functions */

#define SYM_FUNC_START(name)				\

	SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)	\

arch/x86/lib/memcpy_64.S

+2 −1
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
/* Copyright 2002 Andi Kleen */



#include <linux/linkage.h>

#include <linux/cfi_types.h>

#include <asm/errno.h>

#include <asm/cpufeatures.h>

#include <asm/alternative.h>
@@ -27,7 +28,7 @@ 
 * Output:

 * rax original destination

 */

SYM_FUNC_START(__memcpy)

SYM_TYPED_FUNC_START(__memcpy)

	ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \

		      "jmp memcpy_erms", X86_FEATURE_ERMS