From patchwork Thu Jul 22 10:26:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 484139 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=-20.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 C7A38C6377D for ; Thu, 22 Jul 2021 10:26:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ACDFF61285 for ; Thu, 22 Jul 2021 10:26:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231325AbhGVJqQ (ORCPT ); Thu, 22 Jul 2021 05:46:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:57588 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231667AbhGVJqN (ORCPT ); Thu, 22 Jul 2021 05:46:13 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3BC4960FED; Thu, 22 Jul 2021 10:26:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626949571; bh=fHT59LhvE3gc9fM6N3ufqFMTVW0dfEM2SVeZ98t/cB0=; h=From:To:Cc:Subject:Date:From; b=jLlxmgvHZyeju+fi7zxuu2/WjWE6Cbc5+kLfAtzW/jhnNuA1kcGtCe8LbdKJnmXGB O3Ht0J1et3VdswiquEdvtfiHBcBH1u/ivS778uPWzOBgQE0XzdgFz0MOWO4AM72YA3 Pyl4a8/lstZIrPORrhJ97AOguvzx94E+cabq+Km3OCdycM2+BkvOUYdjcEP6Pj1e2A qstAPldzEX3IS9SDa1S01ZEpaDQjV1N4Pk9eyM4IwMmMv1v682tT/nV+i1xBXKFeJm E2b5uuGWr82sLe9fk6mxJfGWzMZa0DpehTo9VyWL92fOW7LkXRlc6d7SY+M34K3+8u mIdWJTVV1PfKQ== From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Benjamin Herrenschmidt Subject: [PATCH] efistub: arm64: relax 2M alignment again for relocatable kernels Date: Thu, 22 Jul 2021 12:26:00 +0200 Message-Id: <20210722102600.58392-1-ardb@kernel.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Commit 82046702e288 ("efi/libstub/arm64: Replace 'preferred' offset with alignment check") simplified the way the stub moves the kernel image around in memory before booting it, given that a relocatable image does not need to be copied to a 2M aligned offset if it was loaded on a 64k boundary by EFI. Commit d32de9130f6c ("efi/arm64: libstub: Deal gracefully with EFI_RNG_PROTOCOL failure") inadvertently defeated this logic by overriding the value of efi_nokaslr if EFI_RNG_PROTOCOL is not available, which was mistaked by the loader logic as an explicit request on the part of the user to disable KASLR and any associated relocation of an Image not loaded on a 2M boundary. So let's reinstate this functionality, by capturing the value of efi_nokaslr at function entry to choose the minimum alignment. Fixes: d32de9130f6c ("efi/arm64: libstub: Deal gracefully with EFI_RNG_PROTOCOL failure") Cc: Benjamin Herrenschmidt Signed-off-by: Ard Biesheuvel --- This fixes the regression that was discussed in [0], but given that it is very likely to break Ben's use case again, I'll sit on it for the time being. [0] https://lore.kernel.org/linux-efi/161920fc31ec4168290ca31b3e4ac7a75ac1df6b.camel@kernel.crashing.org/ drivers/firmware/efi/libstub/arm64-stub.c | 28 +++++++++----------- 1 file changed, 13 insertions(+), 15 deletions(-) diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 7bf0a7acae5e..98e013404ca3 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -34,18 +34,6 @@ efi_status_t check_platform_features(void) return EFI_SUCCESS; } -/* - * Although relocatable kernels can fix up the misalignment with respect to - * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of - * sync with those recorded in the vmlinux when kaslr is disabled but the - * image required relocation anyway. Therefore retain 2M alignment unless - * KASLR is in use. - */ -static u64 min_kimg_align(void) -{ - return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; -} - efi_status_t handle_kernel_image(unsigned long *image_addr, unsigned long *image_size, unsigned long *reserve_addr, @@ -56,6 +44,16 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, unsigned long kernel_size, kernel_memsize = 0; u32 phys_seed = 0; + /* + * Although relocatable kernels can fix up the misalignment with + * respect to MIN_KIMG_ALIGN, the resulting virtual text addresses are + * subtly out of sync with those recorded in the vmlinux when kaslr is + * disabled but the image required relocation anyway. Therefore retain + * 2M alignment if KASLR was explicitly disabled, even if it was not + * going to be activated to begin with. + */ + u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN; + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { if (!efi_nokaslr) { status = efi_get_random_bytes(sizeof(phys_seed), @@ -85,14 +83,14 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, * If KASLR is enabled, and we have some randomness available, * locate the kernel at a randomized offset in physical memory. */ - status = efi_random_alloc(*reserve_size, min_kimg_align(), + status = efi_random_alloc(*reserve_size, min_kimg_align, reserve_addr, phys_seed); } else { status = EFI_OUT_OF_RESOURCES; } if (status != EFI_SUCCESS) { - if (IS_ALIGNED((u64)_text, min_kimg_align())) { + if (IS_ALIGNED((u64)_text, min_kimg_align)) { /* * Just execute from wherever we were loaded by the * UEFI PE/COFF loader if the alignment is suitable. @@ -103,7 +101,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, } status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, - ULONG_MAX, min_kimg_align()); + ULONG_MAX, min_kimg_align); if (status != EFI_SUCCESS) { efi_err("Failed to relocate kernel\n");