From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1kWgPK-0000GS-FY for mharc-grub-devel@gnu.org; Sun, 25 Oct 2020 09:50:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45766) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kWgPJ-0000DM-3z for grub-devel@gnu.org; Sun, 25 Oct 2020 09:50:01 -0400 Received: from foss.arm.com ([217.140.110.172]:38966) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kWgPH-0005wc-5F for grub-devel@gnu.org; Sun, 25 Oct 2020 09:50:00 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6E66530E; Sun, 25 Oct 2020 06:49:58 -0700 (PDT) Received: from e123331-lin.nice.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 23B903F68F; Sun, 25 Oct 2020 06:49:57 -0700 (PDT) From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: Ard Biesheuvel , grub-devel@gnu.org, daniel.kiper@oracle.com, leif@nuviainc.com Subject: [PATCH v2 3/8] efi: move MS-DOS stub out of generic PE header definition Date: Sun, 25 Oct 2020 14:49:36 +0100 Message-Id: <20201025134941.4805-4-ard.biesheuvel@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201025134941.4805-1-ard.biesheuvel@arm.com> References: <20201025134941.4805-1-ard.biesheuvel@arm.com> Received-SPF: pass client-ip=217.140.110.172; envelope-from=ard.biesheuvel@arm.com; helo=foss.arm.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/25 09:49:53 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Oct 2020 13:50:01 -0000 The PE/COFF spec permits the COFF signature and file header to appear anywhere in the file, and the actual offset is recorded in 4 byte little endian field at offset 0x3c of the image. When GRUB is emitted as a PE/COFF binary, we reuse the 128 byte MS-DOS stub (even for non-x86 architectures), putting the COFF signature and file header at offset 0x80. However, other PE/COFF images may use different values, and non-x86 Linux kernels use an offset of 0x40 instead. So let's get rid of the grub_pe32_header struct from pe32.h, given that it does not represent anything defined by the PE/COFF spec. Instead, use the GRUB_PE32_MSDOS_STUB_SIZE macro explicitly to reference the COFF header in the only place in the code where we rely on this. The remaining fields are moved into a struct grub_coff_image_header, which we will use later to access COFF header fields of arbitrary images (and which may therefore appear at different offsets) Signed-off-by: Ard Biesheuvel --- grub-core/kern/efi/efi.c | 5 +++-- include/grub/efi/pe32.h | 5 +---- 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c index e0165e74c587..9e5a72be538d 100644 --- a/grub-core/kern/efi/efi.c +++ b/grub-core/kern/efi/efi.c @@ -282,7 +282,7 @@ grub_addr_t grub_efi_modules_addr (void) { grub_efi_loaded_image_t *image; - struct grub_pe32_header *header; + struct grub_coff_image_header *header; struct grub_pe32_coff_header *coff_header; struct grub_pe32_section_table *sections; struct grub_pe32_section_table *section; @@ -293,7 +293,8 @@ grub_efi_modules_addr (void) if (! image) return 0; - header = image->image_base; + header = (struct grub_coff_image_header *) ((char *) image->image_base + + GRUB_PE32_MSDOS_STUB_SIZE); coff_header = &(header->coff_header); sections = (struct grub_pe32_section_table *) ((char *) coff_header diff --git a/include/grub/efi/pe32.h b/include/grub/efi/pe32.h index 0ed8781f0376..a2da4b318c85 100644 --- a/include/grub/efi/pe32.h +++ b/include/grub/efi/pe32.h @@ -254,11 +254,8 @@ struct grub_pe32_section_table #define GRUB_PE32_SIGNATURE_SIZE 4 -struct grub_pe32_header +struct grub_coff_image_header { - /* This should be filled in with GRUB_PE32_MSDOS_STUB. */ - grub_uint8_t msdos_stub[GRUB_PE32_MSDOS_STUB_SIZE]; - /* This is always PE\0\0. */ char signature[GRUB_PE32_SIGNATURE_SIZE]; -- 2.17.1