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Message-Id: <20200821194310.3089815-1-keescook@chromium.org>
Date: Fri, 21 Aug 2020 12:42:41 -0700
From: Kees Cook <keescook@...omium.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: Kees Cook <keescook@...omium.org>,
Catalin Marinas <catalin.marinas@....com>,
Mark Rutland <mark.rutland@....com>,
Ard Biesheuvel <ardb@...nel.org>,
Peter Collingbourne <pcc@...gle.com>,
James Morse <james.morse@....com>,
Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...hat.com>,
Russell King <linux@...linux.org.uk>,
Masahiro Yamada <masahiroy@...nel.org>,
Arvind Sankar <nivedita@...m.mit.edu>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Nathan Chancellor <natechancellor@...il.com>,
Arnd Bergmann <arnd@...db.de>, x86@...nel.org,
clang-built-linux@...glegroups.com, linux-arch@...r.kernel.org,
linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v6 00/29] Warn on orphan section placement
Hi Ingo,
Based on my testing, this is ready to go. I've reviewed the feedback on
v5 and made a few small changes, noted below.
https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=linker/orphans/warn/v6
v6:
- rebase to -tip x86/boot
- remove 0-sized NOLOAD
- move .got.plt to end with INFO (NOLOAD warns)
- add Reviewed-bys
v5: https://lore.kernel.org/lkml/20200731230820.1742553-1-keescook@chromium.org/
v4: https://lore.kernel.org/lkml/20200629061840.4065483-1-keescook@chromium.org/
v3: https://lore.kernel.org/lkml/20200624014940.1204448-1-keescook@chromium.org/
v2: https://lore.kernel.org/lkml/20200622205815.2988115-1-keescook@chromium.org/
v1: https://lore.kernel.org/lkml/20200228002244.15240-1-keescook@chromium.org/
A recent bug[1] was solved for builds linked with ld.lld, and tracking
it down took way longer than it needed to (a year). Ultimately, it
boiled down to differences between ld.bfd and ld.lld's handling of
orphan sections. Similar situation have continued to recur, and it's
clear the kernel build needs to be much more explicit about linker
sections. Similarly, the recent FGKASLR series brought up orphan section
handling too[2]. In all cases, it would have been nice if the linker was
running with --orphan-handling=warn so that surprise sections wouldn't
silently get mapped into the kernel image at locations up to the whim
of the linker's orphan handling logic. Instead, all desired sections
should be explicitly identified in the linker script (to be either kept,
discarded, or verified to be zero-sized) with any orphans throwing a
warning. The powerpc architecture has actually been doing this for some
time, so this series just extends that coverage to x86, arm, and arm64.
This has gotten sucecssful build testing under the following matrix:
compiler/linker: gcc+ld.bfd, clang+ld.lld
targets: defconfig, allmodconfig
architectures: x86, i386, arm64, arm
versions: -tip x86/boot
All three architectures depend on the first several commits to
vmlinux.lds.h. x86 depends on Arvind's GOT series (in -tip x86/boot now).
arm64 depends on the efi/libstub patch. As such, I'd like to land this
series as a whole. Ingo has suggested he'd take it into -tip.
Thanks!
-Kees
[1] https://github.com/ClangBuiltLinux/linux/issues/282
[2] https://lore.kernel.org/lkml/202002242122.AA4D1B8@keescook/
Kees Cook (28):
vmlinux.lds.h: Create COMMON_DISCARDS
vmlinux.lds.h: Add .gnu.version* to COMMON_DISCARDS
vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections
vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG
vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS
efi/libstub: Disable -mbranch-protection
arm64/mm: Remove needless section quotes
arm64/kernel: Remove needless Call Frame Information annotations
arm64/build: Remove .eh_frame* sections due to unwind tables
arm64/build: Use common DISCARDS in linker script
arm64/build: Add missing DWARF sections
arm64/build: Assert for unwanted sections
arm64/build: Warn on orphan section placement
arm/build: Refactor linker script headers
arm/build: Explicitly keep .ARM.attributes sections
arm/build: Add missing sections
arm/build: Assert for unwanted sections
arm/build: Warn on orphan section placement
arm/boot: Handle all sections explicitly
arm/boot: Warn on orphan section placement
x86/asm: Avoid generating unused kprobe sections
x86/build: Enforce an empty .got.plt section
x86/build: Assert for unwanted sections
x86/build: Warn on orphan section placement
x86/boot/compressed: Reorganize zero-size section asserts
x86/boot/compressed: Remove, discard, or assert for unwanted sections
x86/boot/compressed: Add missing debugging sections to output
x86/boot/compressed: Warn on orphan section placement
Nick Desaulniers (1):
vmlinux.lds.h: add PGO and AutoFDO input sections
arch/alpha/kernel/vmlinux.lds.S | 1 +
arch/arc/kernel/vmlinux.lds.S | 1 +
arch/arm/Makefile | 4 ++
arch/arm/boot/compressed/Makefile | 2 +
arch/arm/boot/compressed/vmlinux.lds.S | 20 +++----
.../arm/{kernel => include/asm}/vmlinux.lds.h | 30 ++++++++--
arch/arm/kernel/vmlinux-xip.lds.S | 8 ++-
arch/arm/kernel/vmlinux.lds.S | 8 ++-
arch/arm64/Makefile | 9 ++-
arch/arm64/kernel/smccc-call.S | 2 -
arch/arm64/kernel/vmlinux.lds.S | 28 +++++++--
arch/arm64/mm/mmu.c | 2 +-
arch/csky/kernel/vmlinux.lds.S | 1 +
arch/hexagon/kernel/vmlinux.lds.S | 1 +
arch/ia64/kernel/vmlinux.lds.S | 1 +
arch/mips/kernel/vmlinux.lds.S | 1 +
arch/nds32/kernel/vmlinux.lds.S | 1 +
arch/nios2/kernel/vmlinux.lds.S | 1 +
arch/openrisc/kernel/vmlinux.lds.S | 1 +
arch/parisc/boot/compressed/vmlinux.lds.S | 1 +
arch/parisc/kernel/vmlinux.lds.S | 1 +
arch/powerpc/kernel/vmlinux.lds.S | 2 +-
arch/riscv/kernel/vmlinux.lds.S | 1 +
arch/s390/kernel/vmlinux.lds.S | 1 +
arch/sh/kernel/vmlinux.lds.S | 1 +
arch/sparc/kernel/vmlinux.lds.S | 1 +
arch/um/kernel/dyn.lds.S | 2 +-
arch/um/kernel/uml.lds.S | 2 +-
arch/x86/Makefile | 4 ++
arch/x86/boot/compressed/Makefile | 2 +
arch/x86/boot/compressed/vmlinux.lds.S | 58 +++++++++++++------
arch/x86/include/asm/asm.h | 6 +-
arch/x86/kernel/vmlinux.lds.S | 39 ++++++++++++-
drivers/firmware/efi/libstub/Makefile | 9 ++-
include/asm-generic/vmlinux.lds.h | 49 +++++++++++++---
35 files changed, 241 insertions(+), 60 deletions(-)
rename arch/arm/{kernel => include/asm}/vmlinux.lds.h (84%)
--
2.25.1
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