From patchwork Mon Jun 28 18:34:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dov Murik X-Patchwork-Id: 468116 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 00032C11F64 for ; Mon, 28 Jun 2021 18:34:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCE2661C85 for ; Mon, 28 Jun 2021 18:34:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234558AbhF1ShX (ORCPT ); Mon, 28 Jun 2021 14:37:23 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:61986 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S234532AbhF1ShW (ORCPT ); Mon, 28 Jun 2021 14:37:22 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 15SIYLDv083139; Mon, 28 Jun 2021 14:34:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=mTHEHqZPDmYqt/tWItKKjdDa5/ESAOzeT5/F7ccqY0M=; b=AvompGET82QF11fpf+ET2aA6wfstg4ZCQtG+Sg1koaoQhtWh3LoAAqwpWnn8Omq4zbxw lF2Be+3D9l3zxsmWas8B05LssRejoYGDeaINwKdH6iibUeOTPn2o6egVdz5imx781MfF 3yChmKlmJNHfOD+W1OK5IYBGnWUI2H2lfspBa7NNWUncxiBtIDw013MUIUzIs+7m8Ztu Q4yigIw327ljJIenV0YhFkcrGxHRy4g30fMqY2NXz/UlyP/dgcwEXXhGwQ80YupI1U+s /22UmUjn+KjIqFWpQ8e3IAfBeC6wIYZ7qJTMQsJHMWwhhL4XonE7ZU2MoPuGXR1jJ7Ju mw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 39fd08dm8t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Jun 2021 14:34:42 -0400 Received: from m0098419.ppops.net (m0098419.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 15SIYgTS083905; Mon, 28 Jun 2021 14:34:42 -0400 Received: from ppma02dal.us.ibm.com (a.bd.3ea9.ip4.static.sl-reverse.com [169.62.189.10]) by mx0b-001b2d01.pphosted.com with ESMTP id 39fd08dm8f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Jun 2021 14:34:41 -0400 Received: from pps.filterd (ppma02dal.us.ibm.com [127.0.0.1]) by ppma02dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 15SISBMe027439; Mon, 28 Jun 2021 18:34:41 GMT Received: from b01cxnp23033.gho.pok.ibm.com (b01cxnp23033.gho.pok.ibm.com [9.57.198.28]) by ppma02dal.us.ibm.com with ESMTP id 39duvb8mtg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 28 Jun 2021 18:34:41 +0000 Received: from b01ledav006.gho.pok.ibm.com (b01ledav006.gho.pok.ibm.com [9.57.199.111]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 15SIYej237355992 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 28 Jun 2021 18:34:40 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EBB86AC069; Mon, 28 Jun 2021 18:34:39 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A3E08AC062; Mon, 28 Jun 2021 18:34:39 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 28 Jun 2021 18:34:39 +0000 (GMT) From: Dov Murik To: linux-efi@vger.kernel.org Cc: Dov Murik , Laszlo Ersek , Ashish Kalra , Brijesh Singh , Tom Lendacky , Ard Biesheuvel , James Morris , "Serge E. Hallyn" , Andi Kleen , "Dr. David Alan Gilbert" , James Bottomley , Tobin Feldman-Fitzthum , Jim Cadden , linux-coco@lists.linux.dev, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 1/3] efi/libstub: Copy confidential computing secret area Date: Mon, 28 Jun 2021 18:34:29 +0000 Message-Id: <20210628183431.953934-2-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210628183431.953934-1-dovmurik@linux.ibm.com> References: <20210628183431.953934-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Sjv0tWuw2YY8xBRTAjrP5FQ5T9ZgF0GO X-Proofpoint-ORIG-GUID: xbvnbsO7Rlu_jCuypXybUjEijIhzZyfd X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-06-28_14:2021-06-25,2021-06-28 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 priorityscore=1501 mlxscore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 malwarescore=0 impostorscore=0 mlxlogscore=999 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106280121 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Confidential computing hardware such as AMD SEV (Secure Encrypted Virtualization) allows a guest owner to inject secrets into the VMs memory without the host/hypervisor being able to read them. Firmware support for secret injection is available in OVMF, which reserves a memory area for secret injection and includes a pointer to it the in EFI config table entry LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_TABLE_GUID. However, OVMF doesn't force the guest OS to keep this memory area reserved. If EFI exposes such a table entry, efi/libstub will copy this area to a reserved memory for future use inside the kernel. A pointer to the new copy is kept in the EFI table under LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_AREA_GUID. Signed-off-by: Dov Murik --- drivers/firmware/efi/libstub/Makefile | 3 +- .../efi/libstub/confidential-computing.c | 68 +++++++++++++++++++ drivers/firmware/efi/libstub/efi-stub.c | 2 + drivers/firmware/efi/libstub/efistub.h | 2 + drivers/firmware/efi/libstub/x86-stub.c | 2 + include/linux/efi.h | 7 ++ 6 files changed, 83 insertions(+), 1 deletion(-) create mode 100644 drivers/firmware/efi/libstub/confidential-computing.c diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index d0537573501e..938ed23dd135 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -55,7 +55,8 @@ KCOV_INSTRUMENT := n lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \ file.o mem.o random.o randomalloc.o pci.o \ skip_spaces.o lib-cmdline.o lib-ctype.o \ - alignedmem.o relocate.o vsprintf.o + alignedmem.o relocate.o vsprintf.o \ + confidential-computing.o # include the stub's generic dependencies from lib/ when building for ARM/arm64 efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c diff --git a/drivers/firmware/efi/libstub/confidential-computing.c b/drivers/firmware/efi/libstub/confidential-computing.c new file mode 100644 index 000000000000..96b97ff5d503 --- /dev/null +++ b/drivers/firmware/efi/libstub/confidential-computing.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Confidential computing secret area handling + * + * Copyright (C) 2021 IBM Corporation + * Author: Dov Murik + */ + +#include +#include +#include + +#include "efistub.h" + +#define LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_TABLE_GUID \ + EFI_GUID(0xadf956ad, 0xe98c, 0x484c, 0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47) + +/** + * struct efi_confidential_computing_secret_table - EFI config table that + * points to the confidential computing secret area. The guid + * LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_TABLE_GUID holds this table. + * @base: Physical address of the EFI secret area + * @size: Size (in bytes) of the EFI secret area + */ +struct efi_confidential_computing_secret_table { + u64 base; + u64 size; +} __attribute((packed)); + +/* + * Create a copy of EFI's confidential computing secret area (if available) so + * that the secrets are accessible in the kernel after ExitBootServices. + */ +void efi_copy_confidential_computing_secret_area(void) +{ + efi_guid_t linux_secret_area_guid = LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_AREA_GUID; + efi_status_t status; + struct efi_confidential_computing_secret_table *secret_table; + struct linux_efi_confidential_computing_secret_area *secret_area; + + secret_table = get_efi_config_table(LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_TABLE_GUID); + if (!secret_table) + return; + + if (secret_table->size == 0 || secret_table->size >= SZ_4G) + return; + + /* Allocate space for the secret area and copy it */ + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, + sizeof(*secret_area) + secret_table->size, (void **)&secret_area); + + if (status != EFI_SUCCESS) { + efi_err("Unable to allocate memory for confidential computing secret area copy\n"); + return; + } + + secret_area->size = secret_table->size; + memcpy(secret_area->area, (void *)(unsigned long)secret_table->base, secret_table->size); + + status = efi_bs_call(install_configuration_table, &linux_secret_area_guid, secret_area); + if (status != EFI_SUCCESS) + goto err_free; + + return; + +err_free: + efi_bs_call(free_pool, secret_area); +} diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c index 26e69788f27a..56bcd94a387e 100644 --- a/drivers/firmware/efi/libstub/efi-stub.c +++ b/drivers/firmware/efi/libstub/efi-stub.c @@ -205,6 +205,8 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, efi_retrieve_tpm2_eventlog(); + efi_copy_confidential_computing_secret_area(); + /* Ask the firmware to clear memory on unclean shutdown */ efi_enable_reset_attack_mitigation(); diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index cde0a2ef507d..1c02658042ea 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -858,4 +858,6 @@ efi_enable_reset_attack_mitigation(void) { } void efi_retrieve_tpm2_eventlog(void); +void efi_copy_confidential_computing_secret_area(void); + #endif diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index f14c4ff5839f..c663bf47370a 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -793,6 +793,8 @@ unsigned long efi_main(efi_handle_t handle, efi_retrieve_tpm2_eventlog(); + efi_copy_confidential_computing_secret_area(); + setup_graphics(boot_params); setup_efi_pci(boot_params); diff --git a/include/linux/efi.h b/include/linux/efi.h index 6b5d36babfcc..4f647f1ee298 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -359,6 +359,8 @@ void efi_native_runtime_setup(void); #define LINUX_EFI_MEMRESERVE_TABLE_GUID EFI_GUID(0x888eb0c6, 0x8ede, 0x4ff5, 0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2) #define LINUX_EFI_INITRD_MEDIA_GUID EFI_GUID(0x5568e427, 0x68fc, 0x4f3d, 0xac, 0x74, 0xca, 0x55, 0x52, 0x31, 0xcc, 0x68) #define LINUX_EFI_MOK_VARIABLE_TABLE_GUID EFI_GUID(0xc451ed2b, 0x9694, 0x45d3, 0xba, 0xba, 0xed, 0x9f, 0x89, 0x88, 0xa3, 0x89) +#define LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_AREA_GUID \ + EFI_GUID(0x940ed1e9, 0xd3da, 0x408b, 0xb3, 0x07, 0xe3, 0x2d, 0x25, 0x4a, 0x65, 0x16) /* OEM GUIDs */ #define DELLEMC_EFI_RCI2_TABLE_GUID EFI_GUID(0x2d9f28a2, 0xa886, 0x456a, 0x97, 0xa8, 0xf1, 0x1e, 0xf2, 0x4f, 0xf4, 0x55) @@ -1282,4 +1284,9 @@ static inline struct efi_mokvar_table_entry *efi_mokvar_entry_find( } #endif +struct linux_efi_confidential_computing_secret_area { + u32 size; + u8 area[]; +}; + #endif /* _LINUX_EFI_H */ From patchwork Mon Jun 28 18:34:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dov Murik X-Patchwork-Id: 468488 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 10F38C11F67 for ; Mon, 28 Jun 2021 18:35:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED62C61456 for ; Mon, 28 Jun 2021 18:35:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234642AbhF1ShZ (ORCPT ); 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Mon, 28 Jun 2021 18:34:42 GMT Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 29685AC060; Mon, 28 Jun 2021 18:34:42 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D1F6BAC059; Mon, 28 Jun 2021 18:34:41 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 28 Jun 2021 18:34:41 +0000 (GMT) From: Dov Murik To: linux-efi@vger.kernel.org Cc: Dov Murik , Laszlo Ersek , Ashish Kalra , Brijesh Singh , Tom Lendacky , Ard Biesheuvel , James Morris , "Serge E. Hallyn" , Andi Kleen , "Dr. David Alan Gilbert" , James Bottomley , Tobin Feldman-Fitzthum , Jim Cadden , linux-coco@lists.linux.dev, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 2/3] efi: Reserve confidential computing secret area Date: Mon, 28 Jun 2021 18:34:30 +0000 Message-Id: <20210628183431.953934-3-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210628183431.953934-1-dovmurik@linux.ibm.com> References: <20210628183431.953934-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 7EF2g0YTvKdrrS4isXcMP20tgipRtHd0 X-Proofpoint-ORIG-GUID: UwF2X2M9KZ2CvsPQikBDpAdO-0r4bGN2 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-06-28_14:2021-06-25,2021-06-28 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=999 adultscore=0 spamscore=0 phishscore=0 suspectscore=0 mlxscore=0 bulkscore=0 impostorscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106280121 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org When efi-stub copies an EFI-provided confidential computing secret area, reserve that memory block for future use within the kernel. Signed-off-by: Dov Murik --- drivers/firmware/efi/Makefile | 2 +- drivers/firmware/efi/confidential-computing.c | 41 +++++++++++++++++++ drivers/firmware/efi/efi.c | 5 +++ include/linux/efi.h | 4 ++ 4 files changed, 51 insertions(+), 1 deletion(-) create mode 100644 drivers/firmware/efi/confidential-computing.c diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index 467e94259679..63f21f7351da 100644 --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile @@ -12,7 +12,7 @@ KASAN_SANITIZE_runtime-wrappers.o := n obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o obj-$(CONFIG_EFI) += efi.o vars.o reboot.o memattr.o tpm.o -obj-$(CONFIG_EFI) += memmap.o +obj-$(CONFIG_EFI) += memmap.o confidential-computing.o ifneq ($(CONFIG_EFI_CAPSULE_LOADER),) obj-$(CONFIG_EFI) += capsule.o endif diff --git a/drivers/firmware/efi/confidential-computing.c b/drivers/firmware/efi/confidential-computing.c new file mode 100644 index 000000000000..e6bb4d1e8f17 --- /dev/null +++ b/drivers/firmware/efi/confidential-computing.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Confidential computing secret area handling + * + * Copyright (C) 2021 IBM Corporation + * Author: Dov Murik + */ + +#define pr_fmt(fmt) "efi: " fmt + +#include +#include +#include +#include + +/* + * Reserve the confidential computing secret area memory + */ +int __init efi_confidential_computing_secret_area_reserve(void) +{ + struct linux_efi_confidential_computing_secret_area *secret_area; + unsigned long secret_area_size; + + if (efi.confidential_computing_secret == EFI_INVALID_TABLE_ADDR) + return 0; + + secret_area = early_memremap(efi.confidential_computing_secret, sizeof(*secret_area)); + if (!secret_area) { + pr_err("Failed to map confidential computing secret area\n"); + efi.confidential_computing_secret = EFI_INVALID_TABLE_ADDR; + return -ENOMEM; + } + + secret_area_size = sizeof(*secret_area) + secret_area->size; + memblock_reserve(efi.confidential_computing_secret, secret_area_size); + + pr_info("Reserved memory of EFI-provided confidential computing secret area"); + + early_memunmap(secret_area, sizeof(*secret_area)); + return 0; +} diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 4b7ee3fa9224..da36333e5c9f 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -526,6 +526,9 @@ static const efi_config_table_type_t common_tables[] __initconst = { #ifdef CONFIG_LOAD_UEFI_KEYS {LINUX_EFI_MOK_VARIABLE_TABLE_GUID, &efi.mokvar_table, "MOKvar" }, #endif + {LINUX_EFI_CONFIDENTIAL_COMPUTING_SECRET_AREA_GUID, + &efi.confidential_computing_secret, + "ConfCompSecret"}, {}, }; @@ -613,6 +616,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables, efi_tpm_eventlog_init(); + efi_confidential_computing_secret_area_reserve(); + if (mem_reserve != EFI_INVALID_TABLE_ADDR) { unsigned long prsv = mem_reserve; diff --git a/include/linux/efi.h b/include/linux/efi.h index 4f647f1ee298..e9740bd16db0 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -551,6 +551,8 @@ extern struct efi { unsigned long tpm_log; /* TPM2 Event Log table */ unsigned long tpm_final_log; /* TPM2 Final Events Log table */ unsigned long mokvar_table; /* MOK variable config table */ + unsigned long confidential_computing_secret; /* Confidential computing */ + /* secret table */ efi_get_time_t *get_time; efi_set_time_t *set_time; @@ -1190,6 +1192,8 @@ extern int efi_tpm_final_log_size; extern unsigned long rci2_table_phys; +extern int efi_confidential_computing_secret_area_reserve(void); + /* * efi_runtime_service() function identifiers. * "NONE" is used by efi_recover_from_page_fault() to check if the page From patchwork Mon Jun 28 18:34:31 2021 Content-Type: text/plain; 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Mon, 28 Jun 2021 18:34:44 +0000 (GMT) Received: from b01ledav006.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CBC2AAC05E; Mon, 28 Jun 2021 18:34:43 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b01ledav006.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 28 Jun 2021 18:34:43 +0000 (GMT) From: Dov Murik To: linux-efi@vger.kernel.org Cc: Dov Murik , Laszlo Ersek , Ashish Kalra , Brijesh Singh , Tom Lendacky , Ard Biesheuvel , James Morris , "Serge E. Hallyn" , Andi Kleen , "Dr. David Alan Gilbert" , James Bottomley , Tobin Feldman-Fitzthum , Jim Cadden , linux-coco@lists.linux.dev, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 3/3] virt: Add sev_secret module to expose confidential computing secrets Date: Mon, 28 Jun 2021 18:34:31 +0000 Message-Id: <20210628183431.953934-4-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210628183431.953934-1-dovmurik@linux.ibm.com> References: <20210628183431.953934-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: Fe-wtuHfLriIPrLX_Bl1P29ufqF5ZvWX X-Proofpoint-GUID: ESaWOHJy8_qcsWKX87Ys8A0mrOxN1xrK X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-06-28_14:2021-06-25,2021-06-28 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 phishscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 clxscore=1015 suspectscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106280121 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org The new sev_secret module exposes the confidential computing secret area via securityfs interface. When the module is loaded (and securityfs is mounted, typically under /sys/kernel/security), an "sev_secret" directory is created in securityfs. In it, a file is created for each secret entry. The name of each such file is the GUID of the secret entry, and its content is the secret data. This allows applications running in a confidential computing setting to read secrets provided by the guest owner via a secure secret injection mechanism (such as AMD SEV's LAUNCH_SECRET command). Removing (unlinking) files in the "sev_secret" directory will zero out the secret in memory, and remove the filesystem entry. If the module is removed and loaded again, that secret will not appear in the filesystem. Signed-off-by: Dov Murik --- drivers/virt/Kconfig | 2 + drivers/virt/Makefile | 1 + drivers/virt/sev_secret/Kconfig | 11 + drivers/virt/sev_secret/Makefile | 2 + drivers/virt/sev_secret/sev_secret.c | 298 +++++++++++++++++++++++++++ 5 files changed, 314 insertions(+) create mode 100644 drivers/virt/sev_secret/Kconfig create mode 100644 drivers/virt/sev_secret/Makefile create mode 100644 drivers/virt/sev_secret/sev_secret.c diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig index 8061e8ef449f..c222cc625891 100644 --- a/drivers/virt/Kconfig +++ b/drivers/virt/Kconfig @@ -36,4 +36,6 @@ source "drivers/virt/vboxguest/Kconfig" source "drivers/virt/nitro_enclaves/Kconfig" source "drivers/virt/acrn/Kconfig" + +source "drivers/virt/sev_secret/Kconfig" endif diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile index 3e272ea60cd9..0765e5418d1d 100644 --- a/drivers/virt/Makefile +++ b/drivers/virt/Makefile @@ -8,3 +8,4 @@ obj-y += vboxguest/ obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/ obj-$(CONFIG_ACRN_HSM) += acrn/ +obj-y += sev_secret/ diff --git a/drivers/virt/sev_secret/Kconfig b/drivers/virt/sev_secret/Kconfig new file mode 100644 index 000000000000..4505526b8ef1 --- /dev/null +++ b/drivers/virt/sev_secret/Kconfig @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: GPL-2.0-only +config AMD_SEV_SECRET_SECURITYFS + tristate "AMD SEV secret area securityfs support" + depends on EFI + select SECURITYFS + help + This is a driver for accessing the AMD SEV secret area via + securityfs. + + To compile this driver as a module, choose M here. + The module will be called sev_secret. diff --git a/drivers/virt/sev_secret/Makefile b/drivers/virt/sev_secret/Makefile new file mode 100644 index 000000000000..9671f7bb3941 --- /dev/null +++ b/drivers/virt/sev_secret/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_AMD_SEV_SECRET_SECURITYFS) += sev_secret.o diff --git a/drivers/virt/sev_secret/sev_secret.c b/drivers/virt/sev_secret/sev_secret.c new file mode 100644 index 000000000000..11a2d41f4711 --- /dev/null +++ b/drivers/virt/sev_secret/sev_secret.c @@ -0,0 +1,298 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * sev_secret module + * + * Copyright (C) 2021 IBM Corporation + * Author: Dov Murik + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/** + * sev_secret: Allow reading confidential computing secret area via securityfs + * interface. + * + * When the module is loaded (and securityfs is mounted, typically under + * /sys/kernel/security), an "sev_secret" directory is created in securityfs. + * In it, a file is created for each secret entry. The name of each such file + * is the GUID of the secret entry, and its content is the secret data. + */ + +#define SEV_SECRET_NUM_FILES 64 + +#define EFI_SEVSECRET_TABLE_HEADER_GUID \ + EFI_GUID(0x1e74f542, 0x71dd, 0x4d66, 0x96, 0x3e, 0xef, 0x42, 0x87, 0xff, 0x17, 0x3b) + +struct sev_secret { + struct dentry *fs_dir; + struct dentry *fs_files[SEV_SECRET_NUM_FILES]; + struct linux_efi_confidential_computing_secret_area *secret_area; +}; + +/* + * Structure of the SEV secret area + * + * Offset Length + * (bytes) (bytes) Usage + * ------- ------- ----- + * 0 16 Secret table header GUID (must be 1e74f542-71dd-4d66-963e-ef4287ff173b) + * 16 4 Length of bytes of the entire secret area + * + * 20 16 First secret entry's GUID + * 36 4 First secret entry's length in bytes (= 16 + 4 + x) + * 40 x First secret entry's data + * + * 40+x 16 Second secret entry's GUID + * 56+x 4 Second secret entry's length in bytes (= 16 + 4 + y) + * 60+x y Second secret entry's data + * + * (... and so on for additional entries) + * + * The GUID of each secret entry designates the usage of the secret data. + */ + +/** + * struct secret_header - Header of entire secret area; this should be followed + * by instances of struct secret_entry. + * @guid: Must be EFI_SEVSECRET_TABLE_HEADER_GUID + * @len: Length in bytes of entire secret area, including header + */ +struct secret_header { + efi_guid_t guid; + u32 len; +} __attribute((packed)); + +/** + * struct secret_entry - Holds one secret entry + * @guid: Secret-specific GUID (or NULL_GUID if this secret entry was deleted) + * @len: Length of secret entry, including its guid and len fields + * @data: The secret data (full of zeros if this secret entry was deleted) + */ +struct secret_entry { + efi_guid_t guid; + u32 len; + u8 data[]; +} __attribute((packed)); + +static size_t secret_entry_data_len(struct secret_entry *e) +{ + return e->len - sizeof(*e); +} + +static struct sev_secret the_sev_secret; + +static inline struct sev_secret *sev_secret_get(void) +{ + return &the_sev_secret; +} + +static int sev_secret_bin_file_show(struct seq_file *file, void *data) +{ + struct secret_entry *e = file->private; + + if (e) + seq_write(file, e->data, secret_entry_data_len(e)); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(sev_secret_bin_file); + +static int sev_secret_unlink(struct inode *dir, struct dentry *dentry) +{ + struct sev_secret *s = sev_secret_get(); + struct inode *inode = d_inode(dentry); + struct secret_entry *e = (struct secret_entry *)inode->i_private; + int i; + + if (e) { + /* Zero out the secret data */ + memzero_explicit(e->data, secret_entry_data_len(e)); + e->guid = NULL_GUID; + } + + inode->i_private = NULL; + + for (i = 0; i < SEV_SECRET_NUM_FILES; i++) + if (s->fs_files[i] == dentry) + s->fs_files[i] = NULL; + + /* securityfs_remove tries to lock the directory's inode, but we reach + * the unlink callback when it's already locked */ + inode_unlock(dir); + securityfs_remove(dentry); + inode_lock(dir); + + return 0; +} + +static const struct inode_operations sev_secret_dir_inode_operations = { + .lookup = simple_lookup, + .unlink = sev_secret_unlink, +}; + +static int sev_secret_map_area(void) +{ + struct sev_secret *s = sev_secret_get(); + struct linux_efi_confidential_computing_secret_area *secret_area; + u32 secret_area_size; + + if (efi.confidential_computing_secret == EFI_INVALID_TABLE_ADDR) { + pr_err("Secret area address is not available\n"); + return -EINVAL; + } + + secret_area = + memremap(efi.confidential_computing_secret, sizeof(*secret_area), MEMREMAP_WB); + if (secret_area == NULL) { + pr_err("Could not map secret area header\n"); + return -ENOMEM; + } + + secret_area_size = sizeof(*secret_area) + secret_area->size; + memunmap(secret_area); + + secret_area = memremap(efi.confidential_computing_secret, secret_area_size, MEMREMAP_WB); + if (secret_area == NULL) { + pr_err("Could not map secret area\n"); + return -ENOMEM; + } + + s->secret_area = secret_area; + return 0; +} + +static void sev_secret_securityfs_teardown(void) +{ + struct sev_secret *s = sev_secret_get(); + int i; + + for (i = (SEV_SECRET_NUM_FILES - 1); i >= 0; i--) { + securityfs_remove(s->fs_files[i]); + s->fs_files[i] = NULL; + } + + securityfs_remove(s->fs_dir); + s->fs_dir = NULL; + + pr_debug("Removed sev_secret securityfs entries\n"); +} + +static int sev_secret_securityfs_setup(void) +{ + efi_guid_t tableheader_guid = EFI_SEVSECRET_TABLE_HEADER_GUID; + struct sev_secret *s = sev_secret_get(); + int ret = 0, i = 0, bytes_left; + unsigned char *ptr; + struct secret_header *h; + struct secret_entry *e; + struct dentry *dent; + char guid_str[EFI_VARIABLE_GUID_LEN + 1]; + + s->fs_dir = NULL; + memset(s->fs_files, 0, sizeof(s->fs_files)); + + dent = securityfs_create_dir("sev_secret", NULL); + if (IS_ERR(dent)) { + pr_err("Error creating SEV secret securityfs directory entry err=%ld", PTR_ERR(dent)); + return PTR_ERR(dent); + } + d_inode(dent)->i_op = &sev_secret_dir_inode_operations; + s->fs_dir = dent; + + ptr = s->secret_area->area; + h = (struct secret_header *)ptr; + if (memcmp(&h->guid, &tableheader_guid, sizeof(h->guid))) { + pr_err("SEV secret area does not start with correct GUID\n"); + ret = -EINVAL; + goto err_cleanup; + } + if (h->len < sizeof(*h)) { + pr_err("SEV secret area reported length is too small\n"); + ret = -EINVAL; + goto err_cleanup; + } + + bytes_left = h->len - sizeof(*h); + ptr += sizeof(*h); + while (bytes_left >= (int)sizeof(*e) && i < SEV_SECRET_NUM_FILES) { + e = (struct secret_entry *)ptr; + if (e->len < sizeof(*e) || e->len > (unsigned int)bytes_left) { + pr_err("SEV secret area is corrupted\n"); + ret = -EINVAL; + goto err_cleanup; + } + + /* Skip deleted entries (which will have NULL_GUID) */ + if (efi_guidcmp(e->guid, NULL_GUID)) { + efi_guid_to_str(&e->guid, guid_str); + + dent = securityfs_create_file(guid_str, 0440, s->fs_dir, (void *)e, + &sev_secret_bin_file_fops); + if (IS_ERR(dent)) { + pr_err("Error creating SEV secret securityfs entry\n"); + ret = PTR_ERR(dent); + goto err_cleanup; + } + + s->fs_files[i++] = dent; + } + ptr += e->len; + bytes_left -= e->len; + } + + pr_debug("Created %d entries in sev_secret securityfs\n", i); + return 0; + +err_cleanup: + sev_secret_securityfs_teardown(); + return ret; +} + +static void sev_secret_unmap_area(void) +{ + struct sev_secret *s = sev_secret_get(); + + if (s->secret_area) { + memunmap(s->secret_area); + s->secret_area = NULL; + } +} + +static int __init sev_secret_init(void) +{ + int ret; + + ret = sev_secret_map_area(); + if (ret) + return ret; + + ret = sev_secret_securityfs_setup(); + if (ret) + goto err_unmap; + + return ret; + +err_unmap: + sev_secret_unmap_area(); + return ret; +} + +static void __exit sev_secret_exit(void) +{ + sev_secret_securityfs_teardown(); + sev_secret_unmap_area(); +} + +module_init(sev_secret_init); +module_exit(sev_secret_exit); + +MODULE_DESCRIPTION("AMD SEV confidential computing secret area access"); +MODULE_AUTHOR("IBM"); +MODULE_LICENSE("GPL");