From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: linux-hardening@vger.kernel.org
Cc: "Kristen C Accardi" <kristen.c.accardi@intel.com>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Masahiro Yamada <masahiroy@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, Jessica Yu <jeyu@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Marios Pomonis <pomonis@google.com>,
Sami Tolvanen <samitolvanen@google.com>,
Tony Luck <tony.luck@intel.com>, Ard Biesheuvel <ardb@kernel.org>,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Lukasz Czapnik <lukasz.czapnik@intel.com>,
"Marta A Plantykow" <marta.a.plantykow@intel.com>,
Michal Kubiak <michal.kubiak@intel.com>,
Michal Swiatkowski <michal.swiatkowski@intel.com>,
Alexander Lobakin <alexandr.lobakin@intel.com>,
linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: [PATCH v6 kspp-next 12/22] linkage: add macros for putting ASM functions into own sections
Date: Tue, 31 Aug 2021 16:41:04 +0200 [thread overview]
Message-ID: <20210831144114.154-13-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <20210831144114.154-1-alexandr.lobakin@intel.com>
With ClangLTO or -ffunction-sections (DCE, FG-KASLR), compiler
places C functions into separate sections by default.
However, this doesn't happen with ASM functions which are still
being placed into .text.
Introduce a pack of macros which generate a new unique section
for the describing function named in the same fashion
(.text.<func_name>).
This will be needed to make input .text section empty to harden
the kernel even more.
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
---
include/linux/linkage.h | 76 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 76 insertions(+)
diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index dbf8506decca..ef8641a7dc1b 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -355,4 +355,80 @@
#endif /* __ASSEMBLY__ */
+/*
+ * Allow ASM symbols to have their own unique sections if they are being
+ * generated by the compiler for C functions (DCE, FG-KASLR, LTO).
+ */
+#if (defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) && !defined(MODULE)) || \
+ (defined(CONFIG_FG_KASLR) && !defined(MODULE)) || \
+ (defined(CONFIG_MODULE_FG_KASLR) && defined(MODULE)) || \
+ (defined(CONFIG_LTO_CLANG))
+
+#define ASM_PUSH_SECTION(name) \
+ ".pushsection .text." #name
+
+#define SYM_TEXT_SECTION(name) \
+ .pushsection .text.##name
+
+#else /* just .text */
+
+#define ASM_PUSH_SECTION(name) \
+ ".pushsection .text"
+
+#define SYM_TEXT_SECTION(name) \
+ .pushsection .text
+
+#endif /* just .text */
+
+#ifdef __ASSEMBLY__
+
+#define SYM_TEXT_END_SECTION \
+ .popsection
+
+#define SYM_FUNC_START_LOCAL_ALIAS_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_FUNC_START_LOCAL_ALIAS(name)
+
+#define SYM_FUNC_START_LOCAL_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_FUNC_START_LOCAL(name)
+
+#define SYM_FUNC_START_NOALIGN_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_FUNC_START_NOALIGN(name)
+
+#define SYM_FUNC_START_WEAK_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_FUNC_START_WEAK(name)
+
+#define SYM_FUNC_START_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_FUNC_START(name)
+
+#define SYM_CODE_START_LOCAL_NOALIGN_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_CODE_START_LOCAL_NOALIGN(name)
+
+#define SYM_CODE_START_NOALIGN_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_CODE_START_NOALIGN(name)
+
+#define SYM_CODE_START_SECTION(name) \
+ SYM_TEXT_SECTION(name) ASM_NL \
+ SYM_CODE_START(name)
+
+#define SYM_FUNC_END_ALIAS_SECTION(name) \
+ SYM_FUNC_END_ALIAS(name) ASM_NL \
+ SYM_TEXT_END_SECTION
+
+#define SYM_FUNC_END_SECTION(name) \
+ SYM_FUNC_END(name) ASM_NL \
+ SYM_TEXT_END_SECTION
+
+#define SYM_CODE_END_SECTION(name) \
+ SYM_CODE_END(name) ASM_NL \
+ SYM_TEXT_END_SECTION
+
+#endif /* __ASSEMBLY__ */
+
#endif /* _LINUX_LINKAGE_H */
--
2.31.1
next prev parent reply other threads:[~2021-08-31 14:43 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-31 14:40 [PATCH v6 kspp-next 00/22] Function Granular KASLR Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 01/22] kbuild: Fix TRIM_UNUSED_KSYMS with LTO_CLANG Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 02/22] kbuild: merge vmlinux_link() between the ordinary link and Clang LTO Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 03/22] kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 04/22] kbuild: merge vmlinux_link() between ARCH=um and other architectures Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 05/22] x86: tools/relocs: Support >64K section headers Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 06/22] x86/boot: Allow a "silent" kaslr random byte fetch Alexander Lobakin
2021-08-31 14:40 ` [PATCH v6 kspp-next 07/22] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 08/22] Make sure ORC lookup covers the entire _etext - _stext Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 09/22] x86/tools: Add relative relocs for randomized functions Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 10/22] x86/boot/compressed: Avoid duplicate malloc() implementations Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 11/22] x86: Add support for function granular KASLR Alexander Lobakin
2021-08-31 14:41 ` Alexander Lobakin [this message]
2021-08-31 14:41 ` [PATCH v6 kspp-next 13/22] x86: conditionally place regular ASM functions into separate sections Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 14/22] FG-KASLR: use a scripted approach to handle .text.* sections Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 15/22] kallsyms: Hide layout Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 16/22] livepatch: only match unique symbols when using fgkaslr Alexander Lobakin
2021-09-09 11:53 ` Miroslav Benes
2021-09-10 12:29 ` Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 17/22] x86/boot: allow FG-KASLR to be selected Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 18/22] arm64/crypto: conditionally place ASM functions into separate sections Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 19/22] module: Reorder functions Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 20/22] module: use a scripted approach for FG-KASLR Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 21/22] Documentation: add a documentation " Alexander Lobakin
2021-08-31 14:41 ` [PATCH v6 kspp-next 22/22] maintainers: add MAINTAINERS entry " Alexander Lobakin
2021-08-31 17:27 ` [PATCH v6 kspp-next 00/22] Function Granular KASLR Kees Cook
2021-09-01 10:36 ` Alexander Lobakin
2021-09-02 1:36 ` Kees Cook
2021-09-03 11:19 ` Alexander Lobakin
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