From patchwork Tue Mar 14 10:13:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Evgeniy Baskov X-Patchwork-Id: 13173980 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9EDCCC7618A for ; Tue, 14 Mar 2023 10:15:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229897AbjCNKP4 (ORCPT ); Tue, 14 Mar 2023 06:15:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229818AbjCNKPy (ORCPT ); Tue, 14 Mar 2023 06:15:54 -0400 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E96297FD0; Tue, 14 Mar 2023 03:15:13 -0700 (PDT) Received: from localhost.localdomain (unknown [83.149.199.65]) by mail.ispras.ru (Postfix) with ESMTPSA id 5A1DC40737D3; Tue, 14 Mar 2023 10:14:00 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 5A1DC40737D3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1678788840; bh=9SzAOcchTEg2AfMbtvtXBF1FJwf4qtt0ARBnHBjGoNU=; h=From:To:Cc:Subject:Date:From; b=TkC9VxqjdhZp6/XY4lxp13Zj5Mzp3vlbM2oaCP8jlaNIsLKw1QJtORS6f7DUQAJkp UXU2p5mNrCZwBvBeUpulRJTrOz1bPIaXo4iZO7CebYbhWdT4myL4OgIERwf2MVDtvo GXSeH2f0vQiDFATGkLRXboAREKbJbQdfrpwpmGck= From: Evgeniy Baskov To: Ard Biesheuvel Cc: Evgeniy Baskov , Borislav Petkov , Andy Lutomirski , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexey Khoroshilov , Peter Jones , Gerd Hoffmann , "Limonciello, Mario" , joeyli , lvc-project@linuxtesting.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v5 00/27] x86_64: Improvements at compressed kernel stage Date: Tue, 14 Mar 2023 13:13:27 +0300 Message-Id: X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org This patchset is aimed * to improve UEFI compatibility of compressed kernel code for x86_64 * to setup proper memory access attributes for code and rodata sections * to implement W^X protection policy throughout the whole execution of compressed kernel for EFISTUB code path. Kernel is made to be more compatible with PE image specification [3], allowing it to be successfully loaded by stricter PE loader implementations like the one from [2]. There is at least one known implementation that uses that loader in production [4]. There are also ongoing efforts to upstream these changes. Also the patchset adds EFI_MEMORY_ATTTRIBUTE_PROTOCOL, included into EFI specification since version 2.10, as a better alternative to using DXE services for memory protection attributes manipulation, since it is defined by the UEFI specification itself and not UEFI PI specification. This protocol is not widely available so the code using DXE services is kept in place as a fallback in case specific implementation does not support the new protocol. One of EFI implementations that already support EFI_MEMORY_ATTTRIBUTE_PROTOCOL is Microsoft Project Mu [5]. Kernel image generation tool (tools/build.c) is refactored as a part of changes that makes PE image more compatible. The patchset implements memory protection for compressed kernel code while executing both inside EFI boot services and outside of them. For EFISTUB code path W^X protection policy is maintained throughout the whole execution of compressed kernel. The latter is achieved by extracting the kernel directly from EFI environment and jumping to it's head immediately after exiting EFI boot services. As a side effect of this change one page table rebuild and a copy of the kernel image is removed. Memory protection inside EFI environment is controlled by the CONFIG_DXE_MEM_ATTRIBUTES option, although with these patches this option also control the use EFI_MEMORY_ATTTRIBUTE_PROTOCOL and memory protection attributes of PE sections and not only DXE services as the name might suggest. Changes in v2: * Fix spelling. * Rebase code to current master. * Split huge patches into smaller ones. * Remove unneeded forward declarations. * Make direct extraction unconditional. * Also make it work for x86_32. * Reduce lower limit of KASLR to 64M. * Make callback interface more logically consistent. * Actually declare callbacks structure before using it. * Mention effect on x86_32 in commit message of "x86/build: Remove RWX sections and align on 4KB". * Clarify commit message of "x86/boot: Increase boot page table size". * Remove "startup32_" prefix on startup32_enable_nx_if_supported. * Move linker generated sections outside of function scope. * Drop some unintended changes. * Drop generating 2 reloc entries. (as I've misread the documentation and there's no need for this change.) * Set has_nx from enable_nx_if_supported correctly. * Move ELF header check to build time. * Set WP at the same time as PG in trampoline code, as it is more logically consistent. * Put x86-specific EFISTUB definitions in x86-stub.h header. * Catch presence of ELF segments violating W^X during build. * Move PE definitions from build.c to a new header file. * Fix generation of PE '.compat' section. I decided to keep protection of compressed kernel blob and '.rodata' separate from '.text' for now, since it does not really have a lot of overhead. Otherwise, all comments on v1 seems to be addressed. I have also included Peter's patches [6-7] into the series for simplicity. Changes in v3: * Setup IDT before issuing cpuid so that AMD SEV #VC handler is set. * Replace memcpy with strncpy to prevent out-of-bounds reads in tools/build.c. * Zero BSS before entering efi_main(), since it can contain garbage when booting via EFI handover protocol. * When booting via EFI don't require init_size of RAM, since in-place unpacking is not used anyway with that interface. This saves ~40M of memory for debian .config. * Setup sections memory protection in efi_main() to cover EFI handover protocol, where EFI sections are likely not properly protected. Changes in v4: * Add one missing identity mapping. * Include following patches improving the use of DXE services: - efi/x86: don't try to set page attributes on 0-sized regions. - efi/x86: don't set unsupported memory attributes Changes in v5: * Fix some warnings reported by the build bot. * Clarify comments about initial page table buffer size and kernel extraction buffer allocation and some commit messages. * Fix make dependencies tracking for W^X compile time check. * Remove unneeded explicit identity mapping of struct efi_info in process_efi_entries() -- it is already mapped at the time of the function execution. * Fix 'nokaslr' command line option. * Remove memory attributes definition patch. It is already upstreamed. * Reduce diff size for "x86/build: Cleanup tools/build.c" * Clean up 32-bit EFISTUB assembly entry: use simpler relative offset expressions and remove unused instruction. * Don't set alignment flags for PE sections. They are only meant for object files. * Rework "x86/build: Make generated PE more spec compliant", so that it does not generate sections dynamically and is overall simpler. * Add Ard's patch removing DOS stub. And another one adding the local copy of boot_params from [8]. * Revert to the old behavior of only relaxing memory attributes with DXE services. Only when EFI_MEMORY_ATTRIBUTE_PROTOCOL is available stricter memory attributes are set. The reworked x86 kernel image build tool patches are based on the ideas from the Ard's RFC patches at [8] and comments to v4 at [9]. Patch "x86/boot: Support 4KB pages for identity mapping" might need review from x86/mm team. Many thanks to Ard Biesheuvel and Andrew Cooper for reviewing the patches, and to Peter Jones , Mario Limonciello and Joey Lee for additional testing! [1] https://lore.kernel.org/lkml/893da11995f93a7ea8f7485d17bf356a@ispras.ru/ [2] https://github.com/acidanthera/audk/tree/secure_pe [3] https://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/pecoff_v83.docx [4] https://www.ispras.ru/en/technologies/asperitas/ [5] https://github.com/microsoft/mu_tiano_platforms [6] https://lore.kernel.org/lkml/20221018205118.3756594-1-pjones@redhat.com/ [7] https://lore.kernel.org/lkml/20221213180403.1308507-2-pjones@redhat.com/ [8] https://lore.kernel.org/linux-efi/20230308202209.2980947-1-ardb@kernel.org/ [9] https://lore.kernel.org/lkml/CAMj1kXGu0uFynyt=MostXo58A4f4Zu6cFFiSShFZChU5LWt1ZQ@mail.gmail.com/ Ard Biesheuvel (2): x86: decompressor: Remove the 'bugger off' message efi: x86: Use private copy of struct setup_header Evgeniy Baskov (23): x86/boot: Align vmlinuz sections on page size x86/build: Remove RWX sections and align on 4KB x86/boot: Set cr0 to known state in trampoline x86/boot: Increase boot page table size x86/boot: Support 4KB pages for identity mapping x86/boot: Setup memory protection for bzImage code x86/build: Check W^X of vmlinux during build x86/boot: Map memory explicitly x86/boot: Remove mapping from page fault handler efi/libstub: Move helper function to related file x86/boot: Make console interface more abstract x86/boot: Make kernel_add_identity_map() a pointer x86/boot: Split trampoline and pt init code x86/boot: Add EFI kernel extraction interface efi/x86: Support extracting kernel from libstub x86/boot: Reduce lower limit of physical KASLR tools/include: Add simplified version of pe.h x86/build: Cleanup tools/build.c x86/build: Add SETUP_HEADER_OFFSET constant x86/build: set type_of_loader for EFISTUB efi/libstub: Don't set ramdisk_image/ramdisk_size x86/build: Make generated PE more spec compliant efi/libstub: Use memory attribute protocol Peter Jones (2): efi/libstub: make memory protection warnings include newlines. efi/x86: don't try to set page attributes on 0-sized regions. arch/x86/boot/Makefile | 2 +- arch/x86/boot/compressed/Makefile | 9 +- arch/x86/boot/compressed/acpi.c | 21 +- arch/x86/boot/compressed/efi.c | 19 +- arch/x86/boot/compressed/head_32.S | 43 +- arch/x86/boot/compressed/head_64.S | 89 +++- arch/x86/boot/compressed/ident_map_64.c | 123 +++-- arch/x86/boot/compressed/kaslr.c | 6 +- arch/x86/boot/compressed/misc.c | 284 ++++++----- arch/x86/boot/compressed/misc.h | 23 +- arch/x86/boot/compressed/pgtable.h | 20 - arch/x86/boot/compressed/pgtable_64.c | 71 +-- arch/x86/boot/compressed/putstr.c | 130 +++++ arch/x86/boot/compressed/sev.c | 6 +- arch/x86/boot/compressed/vmlinux.lds.S | 16 +- arch/x86/boot/header.S | 109 ++-- arch/x86/boot/setup.ld | 7 +- arch/x86/boot/tools/build.c | 475 +++++++++++------- arch/x86/include/asm/boot.h | 28 +- arch/x86/include/asm/init.h | 8 +- arch/x86/include/asm/shared/extract.h | 26 + arch/x86/include/asm/shared/pgtable.h | 29 ++ arch/x86/kernel/vmlinux.lds.S | 15 +- arch/x86/mm/ident_map.c | 185 +++++-- drivers/firmware/efi/Kconfig | 2 + drivers/firmware/efi/libstub/Makefile | 2 +- drivers/firmware/efi/libstub/efistub.h | 9 +- drivers/firmware/efi/libstub/mem.c | 194 +++++++ .../firmware/efi/libstub/x86-extract-direct.c | 217 ++++++++ drivers/firmware/efi/libstub/x86-stub.c | 227 +-------- drivers/firmware/efi/libstub/x86-stub.h | 14 + tools/include/linux/pe.h | 150 ++++++ 32 files changed, 1753 insertions(+), 806 deletions(-) delete mode 100644 arch/x86/boot/compressed/pgtable.h create mode 100644 arch/x86/boot/compressed/putstr.c create mode 100644 arch/x86/include/asm/shared/extract.h create mode 100644 arch/x86/include/asm/shared/pgtable.h create mode 100644 drivers/firmware/efi/libstub/x86-extract-direct.c create mode 100644 drivers/firmware/efi/libstub/x86-stub.h create mode 100644 tools/include/linux/pe.h