From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51511C433E1 for ; Wed, 15 Jul 2020 09:00:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24C802064C for ; Wed, 15 Jul 2020 09:00:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="G7nhBArn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729969AbgGOJAW (ORCPT ); Wed, 15 Jul 2020 05:00:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729856AbgGOJAW (ORCPT ); Wed, 15 Jul 2020 05:00:22 -0400 Received: from mail-il1-x144.google.com (mail-il1-x144.google.com [IPv6:2607:f8b0:4864:20::144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 188E2C061755 for ; Wed, 15 Jul 2020 02:00:22 -0700 (PDT) Received: by mail-il1-x144.google.com with SMTP id p15so1289445ilh.13 for ; Wed, 15 Jul 2020 02:00:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=3PdI5My1859p1IPLjt/fTz0M9NmoIv3OJiR/upvR4pU=; b=G7nhBArnI8dDAWLzn7t0gQ4Jw6E5u2epv+qWi1FMPk19Ks9IQ5Yk+pdt1G4MuhUNLh 5EJA8w3hkiIKnjeBGkuLfF3UOfRDw9OiDLQ3+Pjhbg/6a8hglmIkUZ7+Mk9bKKmF8QJi 0jMtaco5NjQRCTNiQTowWYrt/X1jGkiWY+DRet5809UxazXutq86yJ9xZWtJG3LV++eZ X+RR+wc4XEoPvcLFG48avjW0OYTneDVSLuf3B/FMx1mUPtBDJ+zTFGcAn1vAq/GSLVkP JQ97ms0xaQzSICQ+QllqWF1BfY17i3zDxYGLaLcy4oj26GTSLtDiVBUdObhHLFoAvAcA zvcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=3PdI5My1859p1IPLjt/fTz0M9NmoIv3OJiR/upvR4pU=; b=GcQFVCwU4tdGCN8KveKObK/moQjVCTPFzNoSimSKuF+578FlVTKEqm6e8D/3P1JNK4 XkZY3Ys0NVCFfsUPUpvRCPdTqDqGUn0/faFkvtRODdcBE7r23XXVwpshQifILxBQFvTO oB5Hr8IMVEzSKxY0cbT0/Xq9+uXiYApt8C5sZSQlRUfIjw1Fec4HezxeWnb9uUwLP/u+ fHjIrDNDG+/BlArk0lcgnXb0WLx9j7aolJZdCh8eM2jj8i/nm5YqEB5ZkdjbyaYm0o7D byRC46V+nmnwhpz9yGE5SCiOuP+P3l6FhedTulFCdYgYmDYf7lsbnOpRsXKGp0L47t2P Qy3w== X-Gm-Message-State: AOAM530hWQW550797aECDCRWfkmn37Jt51UorZVFJW9qgDZERTsHpK4P Sopt/0yLC9kvOnBFJny4or+KtCUVVnlm1mDrXQTE0EJcWxNMwg== X-Google-Smtp-Source: ABdhPJwiw/V5cpY9X6o1hhpnLP60M2kWqRtih7nyoTLY1Oqm1DwTl58fYIRsUILEXnNuN94k5Qv2v+VQsvepukPDYWg= X-Received: by 2002:a92:8b11:: with SMTP id i17mr8783455ild.212.1594803621436; Wed, 15 Jul 2020 02:00:21 -0700 (PDT) MIME-Version: 1.0 References: <20200714023836.2310569-1-nivedita@alum.mit.edu> <20200715004133.1430068-8-nivedita@alum.mit.edu> In-Reply-To: <20200715004133.1430068-8-nivedita@alum.mit.edu> Reply-To: sedat.dilek@gmail.com From: Sedat Dilek Date: Wed, 15 Jul 2020 11:00:10 +0200 Message-ID: Subject: Re: [PATCH v5 7/7] x86/boot: Check that there are no run-time relocations To: Arvind Sankar Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Nick Desaulniers , Fangrui Song , Dmitry Golovin , Clang-Built-Linux ML , Ard Biesheuvel , Masahiro Yamada , Daniel Kiper , Kees Cook , Nathan Chancellor , Arnd Bergmann , "H . J . Lu" , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 15, 2020 at 2:41 AM Arvind Sankar wrote: > > Add a linker script check that there are no run-time relocations, and > remove the old one that tries to check via looking for specially-named > sections in the object files. > > Drop the tests for -fPIE compiler option and -pie linker option, as they > are available in all supported gcc and binutils versions (as well as > clang and lld). > Tested-by: Sedat Dilek Reported-by: Sedat Dilek Here I reported the breakage with LLD and tested the move to LDFLAGS_vmlinux with a previous version of the patch. - Sedat - > Reviewed-by: Kees Cook > Reviewed-by: Ard Biesheuvel > Reviewed-by: Fangrui Song > Signed-off-by: Arvind Sankar > --- > arch/x86/boot/compressed/Makefile | 28 +++----------------------- > arch/x86/boot/compressed/vmlinux.lds.S | 8 ++++++++ > 2 files changed, 11 insertions(+), 25 deletions(-) > > diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile > index ae2c0dc98a6a..a9e082b8c720 100644 > --- a/arch/x86/boot/compressed/Makefile > +++ b/arch/x86/boot/compressed/Makefile > @@ -29,7 +29,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \ > vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4 > > KBUILD_CFLAGS := -m$(BITS) -O2 > -KBUILD_CFLAGS += -fno-strict-aliasing $(call cc-option, -fPIE, -fPIC) > +KBUILD_CFLAGS += -fno-strict-aliasing -fPIE > KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING > cflags-$(CONFIG_X86_32) := -march=i386 > cflags-$(CONFIG_X86_64) := -mcmodel=small > @@ -51,7 +51,7 @@ UBSAN_SANITIZE :=n > KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) > # Compressed kernel should be built as PIE since it may be loaded at any > # address by the bootloader. > -LDFLAGS_vmlinux := $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker) > +LDFLAGS_vmlinux := -pie $(call ld-option, --no-dynamic-linker) > LDFLAGS_vmlinux += -T > > hostprogs := mkpiggy > @@ -86,30 +86,8 @@ vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o > vmlinux-objs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a > vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o > > -# The compressed kernel is built with -fPIC/-fPIE so that a boot loader > -# can place it anywhere in memory and it will still run. However, since > -# it is executed as-is without any ELF relocation processing performed > -# (and has already had all relocation sections stripped from the binary), > -# none of the code can use data relocations (e.g. static assignments of > -# pointer values), since they will be meaningless at runtime. This check > -# will refuse to link the vmlinux if any of these relocations are found. > -quiet_cmd_check_data_rel = DATAREL $@ > -define cmd_check_data_rel > - for obj in $(filter %.o,$^); do \ > - $(READELF) -S $$obj | grep -qF .rel.local && { \ > - echo "error: $$obj has data relocations!" >&2; \ > - exit 1; \ > - } || true; \ > - done > -endef > - > -# We need to run two commands under "if_changed", so merge them into a > -# single invocation. > -quiet_cmd_check-and-link-vmlinux = LD $@ > - cmd_check-and-link-vmlinux = $(cmd_check_data_rel); $(cmd_ld) > - > $(obj)/vmlinux: $(vmlinux-objs-y) FORCE > - $(call if_changed,check-and-link-vmlinux) > + $(call if_changed,ld) > > OBJCOPYFLAGS_vmlinux.bin := -R .comment -S > $(obj)/vmlinux.bin: vmlinux FORCE > diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S > index a4a4a59a2628..29df99b6cc64 100644 > --- a/arch/x86/boot/compressed/vmlinux.lds.S > +++ b/arch/x86/boot/compressed/vmlinux.lds.S > @@ -42,6 +42,12 @@ SECTIONS > *(.rodata.*) > _erodata = . ; > } > + .rel.dyn : { > + *(.rel.*) > + } > + .rela.dyn : { > + *(.rela.*) > + } > .got : { > *(.got) > } > @@ -85,3 +91,5 @@ ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT en > #else > ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0xc, "Unexpected GOT/PLT entries detected!") > #endif > + > +ASSERT(SIZEOF(.rel.dyn) == 0 && SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations detected!") > -- > 2.26.2 >