From patchwork Tue Oct 25 14:12:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evgeniy Baskov X-Patchwork-Id: 13019331 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 02880ECDFA1 for ; Tue, 25 Oct 2022 14:14:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233029AbiJYOOP (ORCPT ); Tue, 25 Oct 2022 10:14:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232978AbiJYONu (ORCPT ); Tue, 25 Oct 2022 10:13:50 -0400 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64423A3A98; Tue, 25 Oct 2022 07:13:49 -0700 (PDT) Received: from localhost.localdomain (unknown [83.149.199.65]) by mail.ispras.ru (Postfix) with ESMTPSA id D439340737A1; Tue, 25 Oct 2022 14:13:47 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru D439340737A1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1666707227; bh=EwGUAT+V+D/fvt7ukarce/X9DVxbqrCy0Vh2rp1s7+o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AVqWWoXZI9tBYsQ1lkC5/lEq7XnwOexMTfKDrNHL1M/ZC+on1RfeFA7tv+ivI/1Qo eEOlnvVGLge1fCmbJEk9UYgrYLqOvD7Xdg+W+c0KhlASU5I7eQ8O5DsdsZ2ZpZyX9w V+i3ag0LEcvC/Fr8qcFi5yOroDGOpFJ1P4ab/NwI= 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 , lvc-project@linuxtesting.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 10/23] efi/libstub: Move helper function to related file Date: Tue, 25 Oct 2022 17:12:48 +0300 Message-Id: <70dd035f58199cb933526303792ef238080a235c.1666705333.git.baskov@ispras.ru> X-Mailer: git-send-email 2.37.4 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org efi_adjust_memory_range_protection() can be useful outside x86-stub.c. Move it to mem.c, where memory related code resides and make it non-static. Change its behavior to setup exact attributes and disallow making memory regions readable and writable simultaneously for supported configurations. Signed-off-by: Evgeniy Baskov --- drivers/firmware/efi/libstub/efistub.h | 4 + drivers/firmware/efi/libstub/mem.c | 102 ++++++++++++++++++++++++ drivers/firmware/efi/libstub/x86-stub.c | 66 ++------------- 3 files changed, 112 insertions(+), 60 deletions(-) diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index a30fb5d8ef05..63f5157341fe 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -917,6 +917,10 @@ efi_status_t efi_relocate_kernel(unsigned long *image_addr, unsigned long alignment, unsigned long min_addr); +efi_status_t efi_adjust_memory_range_protection(unsigned long start, + unsigned long size, + unsigned long attributes); + efi_status_t efi_parse_options(char const *cmdline); void efi_parse_option_graphics(char *option); diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c index 45841ef55a9f..cdf1e6fb6430 100644 --- a/drivers/firmware/efi/libstub/mem.c +++ b/drivers/firmware/efi/libstub/mem.c @@ -125,3 +125,105 @@ void efi_free(unsigned long size, unsigned long addr) nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE; efi_bs_call(free_pages, addr, nr_pages); } + +/** + * efi_adjust_memory_range_protection() - change memory range protection attributes + * @start: memory range start address + * @size: memory range size + * + * Actual memory range for which memory attributes are modified is + * the smallest ranged with start address and size aligned to EFI_PAGE_SIZE + * that includes [start, start + size]. + * + * @return: status code + */ +efi_status_t efi_adjust_memory_range_protection(unsigned long start, + unsigned long size, + unsigned long attributes) +{ + efi_status_t status; + efi_gcd_memory_space_desc_t desc; + efi_physical_addr_t end, next; + efi_physical_addr_t rounded_start, rounded_end; + efi_physical_addr_t unprotect_start, unprotect_size; + + if (efi_dxe_table == NULL) + return EFI_UNSUPPORTED; + + /* + * This function should not be used to modify attributes + * other than writable/executable. + */ + + if ((attributes & ~(EFI_MEMORY_RO | EFI_MEMORY_XP)) != 0) + return EFI_INVALID_PARAMETER; + + /* + * Disallow simultaniously executable and writable memory + * to inforce W^X policy if direct extraction code is enabled. + */ + + if ((attributes & (EFI_MEMORY_RO | EFI_MEMORY_XP)) == 0) { + efi_warn("W^X violation at [%08lx,%08lx]\n", + (unsigned long)rounded_start, + (unsigned long)rounded_end); + } + + rounded_start = rounddown(start, EFI_PAGE_SIZE); + rounded_end = roundup(start + size, EFI_PAGE_SIZE); + + /* + * Don't modify memory region attributes, they are + * already suitable, to lower the possibility to + * encounter firmware bugs. + */ + + for (end = start + size; start < end; start = next) { + + status = efi_dxe_call(get_memory_space_descriptor, + start, &desc); + + if (status != EFI_SUCCESS) { + efi_warn("Unable to get memory descriptor at %lx\n", + start); + return status; + } + + next = desc.base_address + desc.length; + + /* + * Only system memory is suitable for trampoline/kernel image + * placement, so only this type of memory needs its attributes + * to be modified. + */ + + if (desc.gcd_memory_type != EfiGcdMemoryTypeSystemMemory) { + efi_warn("Attempted to change protection of special memory range\n"); + return EFI_UNSUPPORTED; + } + + if (((desc.attributes ^ attributes) & + (EFI_MEMORY_RO | EFI_MEMORY_XP)) == 0) + continue; + + desc.attributes &= ~(EFI_MEMORY_RO | EFI_MEMORY_XP); + desc.attributes |= attributes; + + unprotect_start = max(rounded_start, desc.base_address); + unprotect_size = min(rounded_end, next) - unprotect_start; + + status = efi_dxe_call(set_memory_space_attributes, + unprotect_start, unprotect_size, + desc.attributes); + + if (status != EFI_SUCCESS) { + efi_warn("Unable to unprotect memory range [%08lx,%08lx]: %lx\n", + (unsigned long)unprotect_start, + (unsigned long)(unprotect_start + unprotect_size), + status); + return status; + } + } + + return EFI_SUCCESS; +} diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 33a7811e12c6..2fddb88613cd 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -212,61 +212,6 @@ static void retrieve_apple_device_properties(struct boot_params *boot_params) } } -static void -adjust_memory_range_protection(unsigned long start, unsigned long size) -{ - efi_status_t status; - efi_gcd_memory_space_desc_t desc; - unsigned long end, next; - unsigned long rounded_start, rounded_end; - unsigned long unprotect_start, unprotect_size; - - if (efi_dxe_table == NULL) - return; - - rounded_start = rounddown(start, EFI_PAGE_SIZE); - rounded_end = roundup(start + size, EFI_PAGE_SIZE); - - /* - * Don't modify memory region attributes, they are - * already suitable, to lower the possibility to - * encounter firmware bugs. - */ - - for (end = start + size; start < end; start = next) { - - status = efi_dxe_call(get_memory_space_descriptor, start, &desc); - - if (status != EFI_SUCCESS) - return; - - next = desc.base_address + desc.length; - - /* - * Only system memory is suitable for trampoline/kernel image placement, - * so only this type of memory needs its attributes to be modified. - */ - - if (desc.gcd_memory_type != EfiGcdMemoryTypeSystemMemory || - (desc.attributes & (EFI_MEMORY_RO | EFI_MEMORY_XP)) == 0) - continue; - - unprotect_start = max(rounded_start, (unsigned long)desc.base_address); - unprotect_size = min(rounded_end, next) - unprotect_start; - - status = efi_dxe_call(set_memory_space_attributes, - unprotect_start, unprotect_size, - EFI_MEMORY_WB); - - if (status != EFI_SUCCESS) { - efi_warn("Unable to unprotect memory range [%08lx,%08lx]: %lx\n", - unprotect_start, - unprotect_start + unprotect_size, - status); - } - } -} - /* * Trampoline takes 2 pages and can be loaded in first megabyte of memory * with its end placed between 128k and 640k where BIOS might start. @@ -290,12 +235,12 @@ setup_memory_protection(unsigned long image_base, unsigned long image_size) * and relocated kernel image. */ - adjust_memory_range_protection(TRAMPOLINE_PLACEMENT_BASE, - TRAMPOLINE_PLACEMENT_SIZE); + efi_adjust_memory_range_protection(TRAMPOLINE_PLACEMENT_BASE, + TRAMPOLINE_PLACEMENT_SIZE, 0); #ifdef CONFIG_64BIT if (image_base != (unsigned long)startup_32) - adjust_memory_range_protection(image_base, image_size); + efi_adjust_memory_range_protection(image_base, image_size, 0); #else /* * Clear protection flags on a whole range of possible @@ -305,8 +250,9 @@ setup_memory_protection(unsigned long image_base, unsigned long image_size) * need to remove possible protection on relocated image * itself disregarding further relocations. */ - adjust_memory_range_protection(LOAD_PHYSICAL_ADDR, - KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR); + efi_adjust_memory_range_protection(LOAD_PHYSICAL_ADDR, + KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR, + 0); #endif }