From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
Arvind Sankar <nivedita@alum.mit.edu>,
Atish Patra <atish.patra@wdc.com>,
linux-efi@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Peter Collingbourne <pcc@google.com>,
James Morse <james.morse@arm.com>, Borislav Petkov <bp@suse.de>,
Ingo Molnar <mingo@redhat.com>,
Russell King <linux@armlinux.org.uk>,
Masahiro Yamada <masahiroy@kernel.org>,
Nathan Chancellor <natechancellor@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
x86@kernel.org, clang-built-linux@googlegroups.com,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v6 07/29] efi/libstub: Disable -mbranch-protection
Date: Fri, 21 Aug 2020 12:42:48 -0700 [thread overview]
Message-ID: <20200821194310.3089815-8-keescook@chromium.org> (raw)
In-Reply-To: <20200821194310.3089815-1-keescook@chromium.org>
In preparation for adding --orphan-handling=warn to more architectures,
disable -mbranch-protection, as EFI does not yet support it[1]. This was
noticed due to it producing unwanted .note.gnu.property sections (prefixed
with .init due to the objcopy build step).
However, we must also work around a bug in Clang where the section is
still emitted for code-less object files[2], so also remove the section
during the objcopy.
[1] https://lore.kernel.org/lkml/CAMj1kXHck12juGi=E=P4hWP_8vQhQ+-x3vBMc3TGeRWdQ-XkxQ@mail.gmail.com
[2] https://bugs.llvm.org/show_bug.cgi?id=46480
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: linux-efi@vger.kernel.org
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/firmware/efi/libstub/Makefile | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 5eefd60917df..0c911e391d75 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -18,7 +18,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \
# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
# disable the stackleak plugin
cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
- -fpie $(DISABLE_STACKLEAK_PLUGIN)
+ -fpie $(DISABLE_STACKLEAK_PLUGIN) \
+ $(call cc-option,-mbranch-protection=none)
cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
-fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
@@ -66,6 +67,12 @@ lib-$(CONFIG_X86) += x86-stub.o
CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
+# Even when -mbranch-protection=none is set, Clang will generate a
+# .note.gnu.property for code-less object files (like lib/ctype.c),
+# so work around this by explicitly removing the unwanted section.
+# https://bugs.llvm.org/show_bug.cgi?id=46480
+STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
+
#
# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the
# .bss section, so the .bss section of the EFI stub needs to be included in the
--
2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
clang-built-linux@googlegroups.com,
Catalin Marinas <catalin.marinas@arm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
x86@kernel.org, Nick Desaulniers <ndesaulniers@google.com>,
Russell King <linux@armlinux.org.uk>,
linux-kernel@vger.kernel.org, Atish Patra <atish.patra@wdc.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Ingo Molnar <mingo@redhat.com>, James Morse <james.morse@arm.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Borislav Petkov <bp@suse.de>,
Peter Collingbourne <pcc@google.com>,
Ard Biesheuvel <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH v6 07/29] efi/libstub: Disable -mbranch-protection
Date: Fri, 21 Aug 2020 12:42:48 -0700 [thread overview]
Message-ID: <20200821194310.3089815-8-keescook@chromium.org> (raw)
In-Reply-To: <20200821194310.3089815-1-keescook@chromium.org>
In preparation for adding --orphan-handling=warn to more architectures,
disable -mbranch-protection, as EFI does not yet support it[1]. This was
noticed due to it producing unwanted .note.gnu.property sections (prefixed
with .init due to the objcopy build step).
However, we must also work around a bug in Clang where the section is
still emitted for code-less object files[2], so also remove the section
during the objcopy.
[1] https://lore.kernel.org/lkml/CAMj1kXHck12juGi=E=P4hWP_8vQhQ+-x3vBMc3TGeRWdQ-XkxQ@mail.gmail.com
[2] https://bugs.llvm.org/show_bug.cgi?id=46480
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: linux-efi@vger.kernel.org
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/firmware/efi/libstub/Makefile | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 5eefd60917df..0c911e391d75 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -18,7 +18,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \
# arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly
# disable the stackleak plugin
cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
- -fpie $(DISABLE_STACKLEAK_PLUGIN)
+ -fpie $(DISABLE_STACKLEAK_PLUGIN) \
+ $(call cc-option,-mbranch-protection=none)
cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
-fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
@@ -66,6 +67,12 @@ lib-$(CONFIG_X86) += x86-stub.o
CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
+# Even when -mbranch-protection=none is set, Clang will generate a
+# .note.gnu.property for code-less object files (like lib/ctype.c),
+# so work around this by explicitly removing the unwanted section.
+# https://bugs.llvm.org/show_bug.cgi?id=46480
+STUBCOPY_FLAGS-y += --remove-section=.note.gnu.property
+
#
# For x86, bootloaders like systemd-boot or grub-efi do not zero-initialize the
# .bss section, so the .bss section of the EFI stub needs to be included in the
--
2.25.1
_______________________________________________
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linux-arm-kernel@lists.infradead.org
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next prev parent reply other threads:[~2020-08-21 19:46 UTC|newest]
Thread overview: 160+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 19:42 [PATCH v6 00/29] Warn on orphan section placement Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-08-21 19:42 ` [PATCH v6 01/29] vmlinux.lds.h: Create COMMON_DISCARDS Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 02/29] vmlinux.lds.h: Add .gnu.version* to COMMON_DISCARDS Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 03/29] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 04/29] vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:48 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 05/29] vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 06/29] vmlinux.lds.h: add PGO and AutoFDO input sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] vmlinux.lds.h: Add " tip-bot2 for Nick Desaulniers
2020-08-21 19:42 ` Kees Cook [this message]
2020-08-21 19:42 ` [PATCH v6 07/29] efi/libstub: Disable -mbranch-protection Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 08/29] arm64/mm: Remove needless section quotes Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 09/29] arm64/kernel: Remove needless Call Frame Information annotations Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 10/29] arm64/build: Remove .eh_frame* sections due to unwind tables Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 11/29] arm64/build: Use common DISCARDS in linker script Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 12/29] arm64/build: Add missing DWARF sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 13/29] arm64/build: Assert for unwanted sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-10-26 12:29 ` [PATCH v6 13/29] " Geert Uytterhoeven
2020-10-26 12:29 ` Geert Uytterhoeven
2020-10-26 13:29 ` Geert Uytterhoeven
2020-10-26 13:29 ` Geert Uytterhoeven
2020-10-26 16:01 ` Geert Uytterhoeven
2020-10-26 16:01 ` Geert Uytterhoeven
2020-10-26 17:38 ` Ard Biesheuvel
2020-10-26 17:38 ` Ard Biesheuvel
2020-10-26 17:43 ` Geert Uytterhoeven
2020-10-26 17:43 ` Geert Uytterhoeven
2020-10-26 17:48 ` Nick Desaulniers
2020-10-26 17:48 ` Nick Desaulniers
2020-10-26 17:53 ` Geert Uytterhoeven
2020-10-26 17:53 ` Geert Uytterhoeven
2020-10-27 8:37 ` Geert Uytterhoeven
2020-10-27 8:37 ` Geert Uytterhoeven
2020-10-27 19:25 ` Geert Uytterhoeven
2020-10-27 19:25 ` Geert Uytterhoeven
2020-10-27 19:33 ` Ard Biesheuvel
2020-10-27 19:33 ` Ard Biesheuvel
2020-10-27 20:00 ` Arvind Sankar
2020-10-27 20:00 ` Arvind Sankar
2020-10-27 20:12 ` Nick Desaulniers
2020-10-27 20:12 ` Nick Desaulniers
2020-10-27 20:15 ` Ard Biesheuvel
2020-10-27 20:15 ` Ard Biesheuvel
2020-10-27 20:17 ` Nick Desaulniers
2020-10-27 20:17 ` Nick Desaulniers
2020-10-27 20:30 ` Arvind Sankar
2020-10-27 20:30 ` Arvind Sankar
2020-10-27 20:40 ` Nick Desaulniers
2020-10-27 20:40 ` Nick Desaulniers
2020-10-27 21:24 ` Arvind Sankar
2020-10-27 21:24 ` Arvind Sankar
2020-10-27 20:28 ` Nick Desaulniers
2020-10-27 20:28 ` Nick Desaulniers
2020-10-27 20:32 ` Arvind Sankar
2020-10-27 20:32 ` Arvind Sankar
2020-10-27 20:36 ` Nick Desaulniers
2020-10-27 20:36 ` Nick Desaulniers
2020-10-28 21:36 ` Alexei Starovoitov
2020-10-28 21:36 ` Alexei Starovoitov
2020-10-27 8:51 ` Geert Uytterhoeven
2020-10-27 8:51 ` Geert Uytterhoeven
2020-10-27 10:08 ` Jean-Philippe Brucker
2020-10-27 10:08 ` Jean-Philippe Brucker
2020-10-27 10:20 ` Geert Uytterhoeven
2020-10-27 10:20 ` Geert Uytterhoeven
2020-10-27 11:29 ` Ard Biesheuvel
2020-10-27 11:29 ` Ard Biesheuvel
2020-10-27 11:53 ` Naresh Kamboju
2020-10-27 11:53 ` Naresh Kamboju
2020-10-27 13:56 ` Ard Biesheuvel
2020-10-27 13:56 ` Ard Biesheuvel
2020-08-21 19:42 ` [PATCH v6 14/29] arm64/build: Warn on orphan section placement Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-08-21 19:42 ` [PATCH v6 15/29] arm/build: Refactor linker script headers Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 16/29] arm/build: Explicitly keep .ARM.attributes sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 17/29] arm/build: Add missing sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:42 ` [PATCH v6 18/29] arm/build: Assert for unwanted sections Kees Cook
2020-08-21 19:42 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 19/29] arm/build: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-08-21 19:43 ` [PATCH v6 20/29] arm/boot: Handle all sections explicitly Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 21/29] arm/boot: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-08-21 19:43 ` [PATCH v6 22/29] x86/asm: Avoid generating unused kprobe sections Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 23/29] x86/build: Enforce an empty .got.plt section Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 24/29] x86/build: Assert for unwanted sections Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] x86/build: Add asserts " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 25/29] x86/build: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-08-21 19:43 ` [PATCH v6 26/29] x86/boot/compressed: Reorganize zero-size section asserts Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 27/29] x86/boot/compressed: Remove, discard, or assert for unwanted sections Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-08-21 20:01 ` Arvind Sankar
2020-08-21 20:01 ` Arvind Sankar
2020-08-21 21:21 ` Kees Cook
2020-08-21 21:21 ` Kees Cook
2020-08-21 21:28 ` Arvind Sankar
2020-08-21 21:28 ` Arvind Sankar
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 28/29] x86/boot/compressed: Add missing debugging sections to output Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-09-01 11:47 ` [tip: core/build] " tip-bot2 for Kees Cook
2020-08-21 19:43 ` [PATCH v6 29/29] x86/boot/compressed: Warn on orphan section placement Kees Cook
2020-08-21 19:43 ` Kees Cook
2020-08-31 19:41 ` [PATCH v6 00/29] " Kees Cook
2020-08-31 19:41 ` Kees Cook
2020-09-01 7:11 ` Ingo Molnar
2020-09-01 7:11 ` Ingo Molnar
2020-09-01 7:59 ` Ingo Molnar
2020-09-01 7:59 ` Ingo Molnar
2020-09-01 8:16 ` Ingo Molnar
2020-09-01 8:16 ` Ingo Molnar
2020-09-01 15:17 ` Kees Cook
2020-09-01 15:17 ` Kees Cook
2020-09-01 18:02 ` Nick Desaulniers
2020-09-01 18:02 ` Nick Desaulniers
2020-09-01 23:18 ` Kees Cook
2020-09-01 23:18 ` Kees Cook
2020-09-01 23:54 ` Nick Desaulniers
2020-09-01 23:54 ` Nick Desaulniers
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