From patchwork Mon Feb 28 11:42:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dov Murik X-Patchwork-Id: 12763064 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 25F28C433EF for ; Mon, 28 Feb 2022 11:43:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232343AbiB1LoO (ORCPT ); Mon, 28 Feb 2022 06:44:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231209AbiB1LoN (ORCPT ); Mon, 28 Feb 2022 06:44:13 -0500 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8707541315; Mon, 28 Feb 2022 03:43:33 -0800 (PST) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 21SAfrkD020461; Mon, 28 Feb 2022 11:43:03 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : content-transfer-encoding : mime-version; s=pp1; bh=0xCp/ATpsuD2F+JEa6OQf2m5ItqJIR8e3PtY1vfYToA=; b=dXCtt3yqeP1xPQW6d70whkHxA6uAIhoo9o7m/pZZ+w4dQtn4m1zBiudK6LIKvSVVFzQl QkbaZYpiQ9F6Db6mhoKODpXpRgB87ag7JZ4Ho9fZ5XbQbr05+gSfj3uvOcA8AZG1hBx2 hbuTmc7rOAGA/n/lOCJbwSbvG8mLUZ0zWHGcz3dmWX7jnUzKaB53BhgjJ9x8GnWw9SyC xqMdDUfQrvWLY2oUdYZOO2oVohOrI+Ic0BNXmOhaQFzyoCikW6A9TXeyzq9mnE2lt0xL j/JrS/KIwPdCDLV4sGDwzqRTwioVnet9ZvcQZB5JCcCuaC0qgQq8CrIRsyT6X1G+Yfh2 Tg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3egvv31cr5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Feb 2022 11:43:03 +0000 Received: from m0098417.ppops.net (m0098417.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 21SBLDYY022474; Mon, 28 Feb 2022 11:43:02 GMT Received: from ppma05wdc.us.ibm.com (1b.90.2fa9.ip4.static.sl-reverse.com [169.47.144.27]) by mx0a-001b2d01.pphosted.com with ESMTP id 3egvv31cqq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Feb 2022 11:43:02 +0000 Received: from pps.filterd (ppma05wdc.us.ibm.com [127.0.0.1]) by ppma05wdc.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 21SBXPi9026001; Mon, 28 Feb 2022 11:43:01 GMT Received: from b01cxnp22033.gho.pok.ibm.com (b01cxnp22033.gho.pok.ibm.com [9.57.198.23]) by ppma05wdc.us.ibm.com with ESMTP id 3efbu9um1u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Feb 2022 11:43:01 +0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 21SBgwxN34144634 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 28 Feb 2022 11:42:58 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 85B11112064; Mon, 28 Feb 2022 11:42:58 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 28A02112065; Mon, 28 Feb 2022 11:42:58 +0000 (GMT) Received: from amdrome3.watson.ibm.com (unknown [9.2.130.16]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 28 Feb 2022 11:42:58 +0000 (GMT) From: Dov Murik To: linux-efi@vger.kernel.org Cc: Dov Murik , Borislav Petkov , Ashish Kalra , Brijesh Singh , Tom Lendacky , Ard Biesheuvel , James Morris , "Serge E. Hallyn" , Andi Kleen , Greg KH , Andrew Scull , Dave Hansen , "Dr. David Alan Gilbert" , Gerd Hoffmann , Lenny Szubowicz , Peter Gonda , Matthew Garrett , James Bottomley , Tobin Feldman-Fitzthum , Jim Cadden , Daniele Buono , linux-coco@lists.linux.dev, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v8 0/4] Allow guest access to EFI confidential computing secret area Date: Mon, 28 Feb 2022 11:42:50 +0000 Message-Id: <20220228114254.1099945-1-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: tpONIeqnAhBzcjpIF-0WFAKxt-sfRH2i X-Proofpoint-ORIG-GUID: jgAUmGvH9andj8RPrHYImJVHyACnzMdV X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-02-28_04,2022-02-26_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 mlxlogscore=999 malwarescore=0 suspectscore=0 adultscore=0 impostorscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2202280065 Precedence: bulk List-ID: Confidential computing (coco) hardware such as AMD SEV (Secure Encrypted Virtualization) allows guest owners to inject secrets into the VMs memory without the host/hypervisor being able to read them. In SEV, secret injection is performed early in the VM launch process, before the guest starts running. OVMF already reserves designated area for secret injection (in its AmdSev package; see edk2 commit 01726b6d23d4 "OvmfPkg/AmdSev: Expose the Sev Secret area using a configuration table" [1]), but the secrets were not available in the guest kernel. The patch series keeps the address of the EFI-provided memory for injected secrets, and exposes the secrets to userspace via securityfs using a new efi_secret kernel module. The module is autoloaded (by the EFI driver) if the secret area is populated. The first patch in EFI keeps the address of the secret area as passed in the EFI configuration table. The second patch introduces the new efi_secret module that exposes the content of the secret entries as securityfs files, and allows clearing out secrets with a file unlink interface. The third patch auto-loads the efi_secret module during startup if the injected secrets area is populated. The last patch documents the data flow of confidential computing secret injection. As a usage example, consider a guest performing computations on encrypted files. The Guest Owner provides the decryption key (= secret) using the secret injection mechanism. The guest application reads the secret from the efi_secret filesystem and proceeds to decrypt the files into memory and then performs the needed computations on the content. In this example, the host can't read the files from the disk image because they are encrypted. Host can't read the decryption key because it is passed using the secret injection mechanism (= secure channel). Host can't read the decrypted content from memory because it's a confidential (memory-encrypted) guest. This has been tested with AMD SEV and SEV-ES guests, but the kernel side of handling the secret area has no SEV-specific dependencies, and therefore might be usable (perhaps with minor changes) for any confidential computing hardware that can publish the secret area via the standard EFI config table entry. To enable this functionality, set CONFIG_EFI_SECRET=m when building the guest kernel. Here is a simple example for usage of the efi_secret module in a guest to which an EFI secret area with 4 secrets was injected during launch: # ls -la /sys/kernel/security/secrets/coco total 0 drwxr-xr-x 2 root root 0 Jun 28 11:54 . drwxr-xr-x 3 root root 0 Jun 28 11:54 .. -r--r----- 1 root root 0 Jun 28 11:54 736870e5-84f0-4973-92ec-06879ce3da0b -r--r----- 1 root root 0 Jun 28 11:54 83c83f7f-1356-4975-8b7e-d3a0b54312c6 -r--r----- 1 root root 0 Jun 28 11:54 9553f55d-3da2-43ee-ab5d-ff17f78864d2 -r--r----- 1 root root 0 Jun 28 11:54 e6f5a162-d67f-4750-a67c-5d065f2a9910 # hd /sys/kernel/security/secrets/coco/e6f5a162-d67f-4750-a67c-5d065f2a9910 00000000 74 68 65 73 65 2d 61 72 65 2d 74 68 65 2d 6b 61 |these-are-the-ka| 00000010 74 61 2d 73 65 63 72 65 74 73 00 01 02 03 04 05 |ta-secrets......| 00000020 06 07 |..| 00000022 # rm /sys/kernel/security/secrets/coco/e6f5a162-d67f-4750-a67c-5d065f2a9910 # ls -la /sys/kernel/security/secrets/coco total 0 drwxr-xr-x 2 root root 0 Jun 28 11:55 . drwxr-xr-x 3 root root 0 Jun 28 11:54 .. -r--r----- 1 root root 0 Jun 28 11:54 736870e5-84f0-4973-92ec-06879ce3da0b -r--r----- 1 root root 0 Jun 28 11:54 83c83f7f-1356-4975-8b7e-d3a0b54312c6 -r--r----- 1 root root 0 Jun 28 11:54 9553f55d-3da2-43ee-ab5d-ff17f78864d2 [1] https://github.com/tianocore/edk2/commit/01726b6d23d4 --- v8 changes: - Change path of filesystem to /secrets/coco and fix the documentation accordingly (Thanks Gerd, Matthew) - Remove patch 2/5 (of v7) because the latest OVMF release (edk2-stable202202) already contains the fix to mark the launch secret page as EFI_RESERVED_TYPE. v7: https://lore.kernel.org/linux-coco/20220201124413.1093099-1-dovmurik@linux.ibm.com/ v7 changes: - Improve description of efi_secret module in Kconfig. - Fix sparse warnings on pointer address space mismatch (Reported-by: kernel test robot ) v6: https://lore.kernel.org/linux-coco/20211129114251.3741721-1-dovmurik@linux.ibm.com/ v6 changes: - Autoload the efi_secret module if the secret area is populated (thanks Greg KH). - efi_secret: Depend on X86_64 because we use ioremap_encrypted() which is only defined for this arch. - efi_secret.c: Remove unneeded tableheader_guid local variable. - Documentation fixes. v5: https://lore.kernel.org/linux-coco/20211118113359.642571-1-dovmurik@linux.ibm.com/ v5 changes: - Simplify EFI code: instead of copying the secret area, the firmware marks the secret area as EFI_RESERVED_TYPE, and then the uefi_init() code just keeps the pointer as it appears in the EFI configuration table. The use of reserved pages is similar to the AMD SEV-SNP patches for handling SNP-Secrets and SNP-CPUID pages. - In order to handle OVMF releases out there which mark the confidential computing secrets page as EFI_BOOT_SERVICES_DATA, add efi/libstub code that detects this and fixes the E820 map to reserve this page. - In the efi_secret module code, map the secrets page using ioremap_encrypted (again, similar to the AMD SEV-SNP guest patches for accessing SNP-Secrets and SNP-CPUID pages). - Add documentation in Documentation/security/coco/efi_secret. v4: https://lore.kernel.org/linux-coco/20211020061408.3447533-1-dovmurik@linux.ibm.com/ v4 changes: - Guard all the new EFI and efi-stub code (patches 1+2) with #ifdef CONFIG_EFI_COCO_SECRET (thanks Greg KH). Selecting CONFIG_EFI_SECRET=m (patch 3) will enable the EFI parts as well. - Guard call to clflush_cache_range() with #ifdef CONFIG_X86 (Reported-by: kernel test robot ) v3: https://lore.kernel.org/linux-coco/20211014130848.592611-1-dovmurik@linux.ibm.com/ v3 changes: - Rename the module to efi_secret - Remove the exporting of clean_cache_range - Use clflush_cache_range in wipe_memory - Document function wipe_memory - Initialize efi.coco_secret to EFI_INVALID_TABLE_ADDR to correctly detect when there's no secret area published in the EFI configuration tables v2: https://lore.kernel.org/linux-coco/20211007061838.1381129-1-dovmurik@linux.ibm.com v2 changes: - Export clean_cache_range() - When deleteing a secret, call clean_cache_range() after explicit_memzero - Add Documentation/ABI/testing/securityfs-coco-sev_secret v1: https://lore.kernel.org/linux-coco/20210809190157.279332-1-dovmurik@linux.ibm.com/ RFC: https://lore.kernel.org/linux-coco/20210628183431.953934-1-dovmurik@linux.ibm.com/ Dov Murik (4): efi: Save location of EFI confidential computing area virt: Add efi_secret module to expose confidential computing secrets efi: Load efi_secret module if EFI secret area is populated docs: security: Add secrets/coco documentation Documentation/ABI/testing/securityfs-secrets-coco | 51 +++ Documentation/security/index.rst | 1 + Documentation/security/secrets/coco.rst | 103 ++++++ Documentation/security/secrets/index.rst | 9 + arch/x86/platform/efi/efi.c | 3 + drivers/firmware/efi/Kconfig | 16 + drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/coco.c | 58 ++++ drivers/firmware/efi/efi.c | 6 + drivers/virt/Kconfig | 3 + drivers/virt/Makefile | 1 + drivers/virt/coco/efi_secret/Kconfig | 19 ++ drivers/virt/coco/efi_secret/Makefile | 2 + drivers/virt/coco/efi_secret/efi_secret.c | 337 ++++++++++++++++++++ include/linux/efi.h | 10 + 15 files changed, 620 insertions(+) create mode 100644 Documentation/ABI/testing/securityfs-secrets-coco create mode 100644 Documentation/security/secrets/coco.rst create mode 100644 Documentation/security/secrets/index.rst create mode 100644 drivers/firmware/efi/coco.c create mode 100644 drivers/virt/coco/efi_secret/Kconfig create mode 100644 drivers/virt/coco/efi_secret/Makefile create mode 100644 drivers/virt/coco/efi_secret/efi_secret.c base-commit: 7e57714cd0ad2d5bb90e50b5096a0e671dec1ef3