From patchwork Wed Feb 8 11:55:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 93612 Delivered-To: patch@linaro.org Received: by 10.140.20.99 with SMTP id 90csp2648515qgi; Wed, 8 Feb 2017 04:04:29 -0800 (PST) X-Received: by 10.99.23.102 with SMTP id 38mr26870892pgx.188.1486555469302; Wed, 08 Feb 2017 04:04:29 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y1si1704114plb.306.2017.02.08.04.04.29; Wed, 08 Feb 2017 04:04:29 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-efi-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@linaro.org; spf=pass (google.com: best guess record for domain of linux-efi-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-efi-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754219AbdBHME1 (ORCPT + 2 others); Wed, 8 Feb 2017 07:04:27 -0500 Received: from mail-wr0-f176.google.com ([209.85.128.176]:33914 "EHLO mail-wr0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752269AbdBHMET (ORCPT ); Wed, 8 Feb 2017 07:04:19 -0500 Received: by mail-wr0-f176.google.com with SMTP id o16so59312430wra.1 for ; Wed, 08 Feb 2017 04:03:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=AmWke3QCy8R2HAHcrbeTaglGs1JjF0pp5ukWE9LJKlE=; b=j5sRaSUQzL5F/84lQWrUJ34KCBVAKNjnLR/xyfqPdCv0mXjhl5jniomsSk+7zR649Y vP0562xhcTBnsfR/IgxnmcHU5gIh1nG00hY4LogAt+k0SUo9Re6DXj2ca5xnSHD4sMWn eBWZm19/36phLAMITf09P0/TCvD3YTwpRuens= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=AmWke3QCy8R2HAHcrbeTaglGs1JjF0pp5ukWE9LJKlE=; b=iZOukdPSTyrblDzYGCzXjFqzxl+QaVQSUMKW4QWL7DuG/eZZBrR1rOTinaHzOMruqf bwOVPUMl9LbChIP3j5F9yx6j2LtL1L/kPxVWwt0BCQMTZSPHkP51OC8+kbsX/ErIG7YH ddylJNRaeNwOUZcgrGJppi/QW5X1fxFb7DF6GMiX4Xt1WYeZHLvZGPO1+Yis/YLpfKkG /KXJBD2PzaN2KU2nhHkht2f/q5/+oXPE9m83KClXJQhOpqzTso0J7DHCY+slttl6+GOC lb2zlM33zR3+Hc7EkHPDa3vHYgMeP1ivAOteBhBAOBQ+oSBqFz0x0pPcgqLNqD25MSHs tobQ== X-Gm-Message-State: AIkVDXJOavcGc7wvQPJdEynajq8AaArIamJE+fZUQ0QK9CMQzlB81y5xR4YWCJD6jdK/Jptj X-Received: by 10.223.133.131 with SMTP id 3mr18744340wrt.161.1486554996812; Wed, 08 Feb 2017 03:56:36 -0800 (PST) Received: from localhost.localdomain ([160.169.163.122]) by smtp.gmail.com with ESMTPSA id 123sm2974815wml.6.2017.02.08.03.56.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 08 Feb 2017 03:56:36 -0800 (PST) From: Ard Biesheuvel To: linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, leif.lindholm@linaro.org Cc: catalin.marinas@arm.com, linux@armlinux.org.uk, kernel-hardening@lists.openwall.com, labbott@fedoraproject.org, Ard Biesheuvel Subject: [PATCH v2 13/14] arm: efi: split zImage code and data into separate PE/COFF sections Date: Wed, 8 Feb 2017 11:55:46 +0000 Message-Id: <1486554947-3964-14-git-send-email-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1486554947-3964-1-git-send-email-ard.biesheuvel@linaro.org> References: <1486554947-3964-1-git-send-email-ard.biesheuvel@linaro.org> Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org To prevent unintended modifications to the kernel text (malicious or otherwise) while running the EFI stub, describe the kernel image as two separate sections: a .text section with read-execute permissions, covering .text, .rodata, .piggytext and the GOT sections (which the stub does not care about anyway), and a .data section with read-write permissions, covering .data and .bss. This relies on the firmware to actually take the section permission flags into account, but this is something that is currently being implemented in EDK2, which means we will likely start seeing it in the wild between one and two years from now. Signed-off-by: Ard Biesheuvel --- arch/arm/boot/compressed/efi-header.S | 30 ++++++++++++++------ arch/arm/boot/compressed/vmlinux.lds.S | 27 +++++++++++++----- 2 files changed, 41 insertions(+), 16 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/arch/arm/boot/compressed/efi-header.S b/arch/arm/boot/compressed/efi-header.S index 7ff2b2f05e4c..3cf09f7efced 100644 --- a/arch/arm/boot/compressed/efi-header.S +++ b/arch/arm/boot/compressed/efi-header.S @@ -57,16 +57,16 @@ optional_header: .short PE_OPT_MAGIC_PE32 @ PE32 format .byte 0x02 @ MajorLinkerVersion .byte 0x14 @ MinorLinkerVersion - .long _end - __efi_start @ SizeOfCode - .long 0 @ SizeOfInitializedData + .long __pecoff_data_start - __efi_start @ SizeOfCode + .long __pecoff_data_size @ SizeOfInitializedData .long 0 @ SizeOfUninitializedData .long efi_stub_entry - start @ AddressOfEntryPoint .long start_offset @ BaseOfCode - .long 0 @ BaseOfData + .long __pecoff_data_start - start @ BaseOfData extra_header_fields: .long 0 @ ImageBase - .long SZ_512 @ SectionAlignment + .long SZ_4K @ SectionAlignment .long SZ_512 @ FileAlignment .short 0 @ MajorOsVersion .short 0 @ MinorOsVersion @@ -76,7 +76,7 @@ extra_header_fields: .short 0 @ MinorSubsystemVersion .long 0 @ Win32VersionValue - .long _end - start @ SizeOfImage + .long __pecoff_end - start @ SizeOfImage .long start_offset @ SizeOfHeaders .long 0 @ CheckSum .short IMAGE_SUBSYSTEM_EFI_APPLICATION @ Subsystem @@ -97,9 +97,9 @@ extra_header_fields: section_table: .ascii ".text\0\0\0" - .long _end - __efi_start @ VirtualSize + .long __pecoff_data_start - __efi_start @ VirtualSize .long __efi_start @ VirtualAddress - .long _edata - __efi_start @ SizeOfRawData + .long __pecoff_data_start - __efi_start @ SizeOfRawData .long __efi_start @ PointerToRawData .long 0 @ PointerToRelocations .long 0 @ PointerToLineNumbers @@ -107,12 +107,24 @@ section_table: .short 0 @ NumberOfLineNumbers .long IMAGE_SCN_CNT_CODE | \ IMAGE_SCN_MEM_READ | \ - IMAGE_SCN_MEM_WRITE | \ IMAGE_SCN_MEM_EXECUTE @ Characteristics + .ascii ".data\0\0\0" + .long __pecoff_data_size @ VirtualSize + .long __pecoff_data_start - start @ VirtualAddress + .long __pecoff_data_rawsize @ SizeOfRawData + .long __pecoff_data_start - start @ PointerToRawData + .long 0 @ PointerToRelocations + .long 0 @ PointerToLineNumbers + .short 0 @ NumberOfRelocations + .short 0 @ NumberOfLineNumbers + .long IMAGE_SCN_CNT_INITIALIZED_DATA | \ + IMAGE_SCN_MEM_READ | \ + IMAGE_SCN_MEM_WRITE @ Characteristics + .set section_count, (. - section_table) / 40 - .align 9 + .align 12 __efi_start: #endif .endm diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S index 5d50daea466a..144e2f408292 100644 --- a/arch/arm/boot/compressed/vmlinux.lds.S +++ b/arch/arm/boot/compressed/vmlinux.lds.S @@ -51,13 +51,6 @@ SECTIONS *(.rodata) *(.rodata.*) } - .data : { - /* - * The EFI stub always executes from RAM, and runs strictly before the - * decompressor, so we can make an exception for its r/w data, and keep it - */ - *(.data.efistub) - } .piggydata : { *(.piggydata) } @@ -73,6 +66,23 @@ SECTIONS /* ensure the zImage file size is always a multiple of 64 bits */ /* (without a dummy byte, ld just ignores the empty section) */ .pad : { BYTE(0); . = ALIGN(8); } + +#ifdef CONFIG_EFI_STUB + .data : ALIGN(4096) { + __pecoff_data_start = .; + /* + * The EFI stub always executes from RAM, and runs strictly before the + * decompressor, so we can make an exception for its r/w data, and keep it + */ + *(.data.efistub) + __pecoff_data_end = .; + + . = ALIGN(512); + } + __pecoff_data_rawsize = . - ADDR(.data); + . = __pecoff_data_end; +#endif + _edata = .; _magic_sig = ZIMAGE_MAGIC(0x016f2818); @@ -87,6 +97,9 @@ SECTIONS . = ALIGN(8); /* the stack must be 64-bit aligned */ .stack : { *(.stack) } + PROVIDE(__pecoff_data_size = ALIGN(512) - ADDR(.data)); + PROVIDE(__pecoff_end = ALIGN(512)); + .stab 0 : { *(.stab) } .stabstr 0 : { *(.stabstr) } .stab.excl 0 : { *(.stab.excl) }