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From: Sami Tolvanen <samitolvanen@google.com>
To: x86@kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v3 08/16] lkdtm: Use an opaque type for lkdtm_rodata_do_nothing
Date: Tue, 14 Sep 2021 12:10:37 -0700	[thread overview]
Message-ID: <20210914191045.2234020-9-samitolvanen@google.com> (raw)
In-Reply-To: <20210914191045.2234020-1-samitolvanen@google.com>

Use an opaque type for lkdtm_rodata_do_nothing to stop the compiler
from generating a CFI jump table entry that jumps to .rodata.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 drivers/misc/lkdtm/lkdtm.h  | 2 +-
 drivers/misc/lkdtm/perms.c  | 2 +-
 drivers/misc/lkdtm/rodata.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index c212a253edde..2da74236c005 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -137,7 +137,7 @@ void lkdtm_REFCOUNT_TIMING(void);
 void lkdtm_ATOMIC_TIMING(void);
 
 /* rodata.c */
-void lkdtm_rodata_do_nothing(void);
+DECLARE_ASM_FUNC_SYMBOL(lkdtm_rodata_do_nothing);
 
 /* usercopy.c */
 void __init lkdtm_usercopy_init(void);
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index 2dede2ef658f..fa2bd90bd8ee 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -151,7 +151,7 @@ void lkdtm_EXEC_VMALLOC(void)
 
 void lkdtm_EXEC_RODATA(void)
 {
-	execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS);
+	execute_location((void *)lkdtm_rodata_do_nothing, CODE_AS_IS);
 }
 
 void lkdtm_EXEC_USERSPACE(void)
diff --git a/drivers/misc/lkdtm/rodata.c b/drivers/misc/lkdtm/rodata.c
index baacb876d1d9..17ed0ad4e6ae 100644
--- a/drivers/misc/lkdtm/rodata.c
+++ b/drivers/misc/lkdtm/rodata.c
@@ -3,7 +3,7 @@
  * This includes functions that are meant to live entirely in .rodata
  * (via objcopy tricks), to validate the non-executability of .rodata.
  */
-#include "lkdtm.h"
+void lkdtm_rodata_do_nothing(void);
 
 void noinstr lkdtm_rodata_do_nothing(void)
 {
-- 
2.33.0.309.g3052b89438-goog


  parent reply	other threads:[~2021-09-14 19:11 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14 19:10 [PATCH v3 00/16] x86: Add support for Clang CFI Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 01/16] objtool: Add CONFIG_CFI_CLANG support Sami Tolvanen
2021-09-14 19:29   ` Nick Desaulniers
2021-09-14 21:01     ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 02/16] objtool: Add ASM_STACK_FRAME_NON_STANDARD Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 03/16] linkage: Add DECLARE_ASM_FUNC_SYMBOL Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 04/16] cfi: Add DEFINE_CFI_IMMEDIATE_RETURN_STUB Sami Tolvanen
2021-09-14 19:36   ` Nick Desaulniers
2021-09-14 20:32     ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 05/16] tracepoint: Exclude tp_stub_func from CFI checking Sami Tolvanen
2021-09-14 19:39   ` Nick Desaulniers
2021-09-14 19:10 ` [PATCH v3 06/16] ftrace: Use an opaque type for functions not callable from C Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 07/16] lkdtm: Disable UNSET_SMEP with CFI Sami Tolvanen
2021-09-14 19:30   ` Kees Cook
2021-09-14 19:10 ` Sami Tolvanen [this message]
2021-09-14 19:32   ` [PATCH v3 08/16] lkdtm: Use an opaque type for lkdtm_rodata_do_nothing Kees Cook
2021-09-14 19:10 ` [PATCH v3 09/16] x86: Use an opaque type for functions not callable from C Sami Tolvanen
2021-09-14 19:33   ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 10/16] x86/extable: Mark handlers __cficanonical Sami Tolvanen
2021-09-14 19:37   ` Kees Cook
2021-09-14 20:38     ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 11/16] x86/purgatory: Disable CFI Sami Tolvanen
2021-09-14 20:02   ` Nick Desaulniers
2021-09-14 20:30     ` Sami Tolvanen
2021-09-14 22:31       ` Nick Desaulniers
2021-09-15  6:24         ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 12/16] x86, relocs: Ignore __typeid__ relocations Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 13/16] x86, module: " Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 14/16] x86, cpu: Use LTO for cpu.c with CFI Sami Tolvanen
2021-09-14 19:44   ` Kees Cook
2021-09-14 19:46   ` Nick Desaulniers
2021-09-14 19:10 ` [PATCH v3 15/16] x86, kprobes: Fix optprobe_template_func type mismatch Sami Tolvanen
2021-09-14 19:40   ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 16/16] x86, build: Allow CONFIG_CFI_CLANG to be selected Sami Tolvanen

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