From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: [PATCH v5 33/36] x86/boot/compressed: Remove, discard, or assert for unwanted sections Date: Fri, 31 Jul 2020 16:08:17 -0700 Message-ID: <20200731230820.1742553-34-keescook@chromium.org> References: <20200731230820.1742553-1-keescook@chromium.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200731230820.1742553-1-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Thomas Gleixner , Will Deacon Cc: Kees Cook , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , x86@kernel.org, clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org List-Id: linux-arch.vger.kernel.org In preparation for warning on orphan sections, stop the linker from generating the .eh_frame* sections, discard unwanted non-zero-sized generated sections, and enforce other expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Signed-off-by: Kees Cook --- arch/x86/boot/compressed/Makefile | 1 + arch/x86/boot/compressed/vmlinux.lds.S | 14 ++++++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 96d53e300ab6..43b49e1f5b6d 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -49,6 +49,7 @@ GCOV_PROFILE := n UBSAN_SANITIZE :=n KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) +KBUILD_LDFLAGS += $(call ld-option,--no-ld-generated-unwind-info) # Compressed kernel should be built as PIE since it may be loaded at any # address by the bootloader. LDFLAGS_vmlinux := -pie $(call ld-option, --no-dynamic-linker) diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 42dea70a5091..1fb9809a9e61 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -83,6 +83,11 @@ SECTIONS ELF_DETAILS DISCARDS + /DISCARD/ : { + *(.dynamic) *(.dynsym) *(.dynstr) *(.dynbss) + *(.hash) *(.gnu.hash) + *(.note.*) + } /* * Sections that should stay zero sized, which is safer to @@ -93,13 +98,18 @@ SECTIONS } ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!") + .plt (NOLOAD) : { + *(.plt) *(.plt.*) + } + ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!") + /* ld.lld does not like .rel* sections being made "NOLOAD". */ .rel.dyn : { - *(.rel.*) + *(.rel.*) *(.rel_*) } ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!") .rela.dyn : { - *(.rela.*) + *(.rela.*) *(.rela_*) } ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!") } -- 2.25.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727867AbgGaXIs (ORCPT ); Fri, 31 Jul 2020 19:08:48 -0400 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C689C0617A2 for ; Fri, 31 Jul 2020 16:08:48 -0700 (PDT) Received: by mail-pg1-x52c.google.com with SMTP id o13so16808263pgf.0 for ; Fri, 31 Jul 2020 16:08:48 -0700 (PDT) From: Kees Cook Subject: [PATCH v5 33/36] x86/boot/compressed: Remove, discard, or assert for unwanted sections Date: Fri, 31 Jul 2020 16:08:17 -0700 Message-ID: <20200731230820.1742553-34-keescook@chromium.org> In-Reply-To: <20200731230820.1742553-1-keescook@chromium.org> References: <20200731230820.1742553-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Thomas Gleixner , Will Deacon Cc: Kees Cook , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , x86@kernel.org, clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Message-ID: <20200731230817.7VkkhPCBwAXAk57LF7VcQjdVCK6HOOJHlNGbxiT-rb0@z> In preparation for warning on orphan sections, stop the linker from generating the .eh_frame* sections, discard unwanted non-zero-sized generated sections, and enforce other expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Signed-off-by: Kees Cook --- arch/x86/boot/compressed/Makefile | 1 + arch/x86/boot/compressed/vmlinux.lds.S | 14 ++++++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 96d53e300ab6..43b49e1f5b6d 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -49,6 +49,7 @@ GCOV_PROFILE := n UBSAN_SANITIZE :=n KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) +KBUILD_LDFLAGS += $(call ld-option,--no-ld-generated-unwind-info) # Compressed kernel should be built as PIE since it may be loaded at any # address by the bootloader. LDFLAGS_vmlinux := -pie $(call ld-option, --no-dynamic-linker) diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 42dea70a5091..1fb9809a9e61 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -83,6 +83,11 @@ SECTIONS ELF_DETAILS DISCARDS + /DISCARD/ : { + *(.dynamic) *(.dynsym) *(.dynstr) *(.dynbss) + *(.hash) *(.gnu.hash) + *(.note.*) + } /* * Sections that should stay zero sized, which is safer to @@ -93,13 +98,18 @@ SECTIONS } ASSERT(SIZEOF(.got) == 0, "Unexpected GOT entries detected!") + .plt (NOLOAD) : { + *(.plt) *(.plt.*) + } + ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!") + /* ld.lld does not like .rel* sections being made "NOLOAD". */ .rel.dyn : { - *(.rel.*) + *(.rel.*) *(.rel_*) } ASSERT(SIZEOF(.rel.dyn) == 0, "Unexpected run-time relocations (.rel) detected!") .rela.dyn : { - *(.rela.*) + *(.rela.*) *(.rela_*) } ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!") } -- 2.25.1