From patchwork Mon Aug 9 19:01:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dov Murik X-Patchwork-Id: 12427133 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 5A551C4320E for ; Mon, 9 Aug 2021 19:02:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1BA2D610CB for ; Mon, 9 Aug 2021 19:02:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235897AbhHITCw (ORCPT ); Mon, 9 Aug 2021 15:02:52 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:20868 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235816AbhHITCs (ORCPT ); Mon, 9 Aug 2021 15:02:48 -0400 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 179IYR76123862; Mon, 9 Aug 2021 15:02:05 -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=mSMhS5KuMYXSCCHFWTjt0J4W3hRXJ0JBE2fkifaGDT8=; b=bE06FSl3BjrellQqJFsR6WcS0v7Xx6Ye9an8aKm0gpbWo44epPBgMAzBHH/xCHchVvU6 LS2tjSUPIdlYRPJ1JDwQVELd1bKzUWQsnoF7NzX1ZgMbsaO5G6qZIOG7cmc/AyE0vruB pJvLzoXJfOIQ2CJdc2SUIJ8YnRpm6lrKkK4Z9CvpQ4cMZ9W+4VjLFZIsJw/FdYSLZT0G a+qdfV6D9kbqno40tEtf8nE+gDocfwSLRzrGRxD219tNKv/z2Us3rZK2mcA7cGr7fmYs y3EitgrqDSPTPatcPz+lnzbl4Qwuo6Uhdxv5Ho91jp3rNpBuIHGOA+Lg6eCm6287O3ZE cw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3aaa1r6q1r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 09 Aug 2021 15:02:05 -0400 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 179IYTcR124046; Mon, 9 Aug 2021 15:02:05 -0400 Received: from ppma02wdc.us.ibm.com (aa.5b.37a9.ip4.static.sl-reverse.com [169.55.91.170]) by mx0a-001b2d01.pphosted.com with ESMTP id 3aaa1r6q1d-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 09 Aug 2021 15:02:05 -0400 Received: from pps.filterd (ppma02wdc.us.ibm.com [127.0.0.1]) by ppma02wdc.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 179IvHhd011234; Mon, 9 Aug 2021 19:02:04 GMT Received: from b01cxnp23033.gho.pok.ibm.com (b01cxnp23033.gho.pok.ibm.com [9.57.198.28]) by ppma02wdc.us.ibm.com with ESMTP id 3aapj91rpp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 09 Aug 2021 19:02:04 +0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 179J22oC44302746 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 9 Aug 2021 19:02:02 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 816BE112071; Mon, 9 Aug 2021 19:02:02 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 45E3D112076; Mon, 9 Aug 2021 19:02:02 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 9 Aug 2021 19:02:02 +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 , "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: [PATCH 1/3] efi/libstub: Copy confidential computing secret area Date: Mon, 9 Aug 2021 19:01:55 +0000 Message-Id: <20210809190157.279332-2-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210809190157.279332-1-dovmurik@linux.ibm.com> References: <20210809190157.279332-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: d4qlvm2jATro-gsdv75DoPFaV86j-nPb X-Proofpoint-ORIG-GUID: abc141FOsCHp-J3-s_772oha95FxN3nM X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-09_07:2021-08-06,2021-08-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxlogscore=999 mlxscore=0 clxscore=1011 spamscore=0 priorityscore=1501 suspectscore=0 malwarescore=0 bulkscore=0 adultscore=0 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108090131 Precedence: bulk List-ID: Confidential computing (coco) 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_COCO_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_COCO_SECRET_AREA_GUID. Signed-off-by: Dov Murik --- drivers/firmware/efi/libstub/Makefile | 2 +- drivers/firmware/efi/libstub/coco.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 | 6 +++ 6 files changed, 81 insertions(+), 1 deletion(-) create mode 100644 drivers/firmware/efi/libstub/coco.c diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index d0537573501e..d77690b7dfb9 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -55,7 +55,7 @@ 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 coco.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/coco.c b/drivers/firmware/efi/libstub/coco.c new file mode 100644 index 000000000000..bf546b6a3f72 --- /dev/null +++ b/drivers/firmware/efi/libstub/coco.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Confidential computing (coco) secret area handling + * + * Copyright (C) 2021 IBM Corporation + * Author: Dov Murik + */ + +#include +#include +#include + +#include "efistub.h" + +#define LINUX_EFI_COCO_SECRET_TABLE_GUID \ + EFI_GUID(0xadf956ad, 0xe98c, 0x484c, 0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47) + +/** + * struct efi_coco_secret_table - EFI config table that points to the + * confidential computing secret area. The guid + * LINUX_EFI_COCO_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_coco_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_coco_secret_area(void) +{ + efi_guid_t linux_secret_area_guid = LINUX_EFI_COCO_SECRET_AREA_GUID; + efi_status_t status; + struct efi_coco_secret_table *secret_table; + struct linux_efi_coco_secret_area *secret_area; + + secret_table = get_efi_config_table(LINUX_EFI_COCO_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..18b3acd15c85 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_coco_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..d604c6744cef 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_coco_secret_area(void); + #endif diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index f14c4ff5839f..4ad85e1b6191 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_coco_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..9021dd521302 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -359,6 +359,7 @@ 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_COCO_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 +1283,9 @@ static inline struct efi_mokvar_table_entry *efi_mokvar_entry_find( } #endif +struct linux_efi_coco_secret_area { + u32 size; + u8 area[]; +}; + #endif /* _LINUX_EFI_H */ From patchwork Mon Aug 9 19:01:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dov Murik X-Patchwork-Id: 12427129 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 2B02FC4320E for ; Mon, 9 Aug 2021 19:02:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0094F60EBD for ; Mon, 9 Aug 2021 19:02:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235701AbhHITCs (ORCPT ); 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Mon, 9 Aug 2021 19:02:03 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D5F8A112073; Mon, 9 Aug 2021 19:02:02 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 94CC1112063; Mon, 9 Aug 2021 19:02:02 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 9 Aug 2021 19:02:02 +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 , "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: [PATCH 2/3] efi: Reserve confidential computing secret area Date: Mon, 9 Aug 2021 19:01:56 +0000 Message-Id: <20210809190157.279332-3-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210809190157.279332-1-dovmurik@linux.ibm.com> References: <20210809190157.279332-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: dUVrM_Yb-gY7YWV3crCwEJbor29hsv-L X-Proofpoint-ORIG-GUID: 9Cue4pHHFGSLDTjPiPeCAf-GHPmlneMF X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-09_07:2021-08-06,2021-08-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 adultscore=0 mlxscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 lowpriorityscore=0 impostorscore=0 bulkscore=0 suspectscore=0 clxscore=1015 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108090131 Precedence: bulk List-ID: When efi-stub copies an EFI-provided confidential computing (coco) secret area, reserve that memory block for future use within the kernel. Signed-off-by: Dov Murik --- arch/x86/platform/efi/efi.c | 1 + drivers/firmware/efi/Makefile | 2 +- drivers/firmware/efi/coco.c | 41 +++++++++++++++++++++++++++++++++++ drivers/firmware/efi/efi.c | 3 +++ include/linux/efi.h | 3 +++ 5 files changed, 49 insertions(+), 1 deletion(-) create mode 100644 drivers/firmware/efi/coco.c diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 147c30a81f15..35e082e5f603 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -93,6 +93,7 @@ static const unsigned long * const efi_tables[] = { #ifdef CONFIG_LOAD_UEFI_KEYS &efi.mokvar_table, #endif + &efi.coco_secret, }; u64 efi_setup; /* efi setup_data physical address */ diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index 467e94259679..8703ffcca351 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 coco.o ifneq ($(CONFIG_EFI_CAPSULE_LOADER),) obj-$(CONFIG_EFI) += capsule.o endif diff --git a/drivers/firmware/efi/coco.c b/drivers/firmware/efi/coco.c new file mode 100644 index 000000000000..42f477d6188c --- /dev/null +++ b/drivers/firmware/efi/coco.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Confidential computing (coco) 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_coco_secret_area_reserve(void) +{ + struct linux_efi_coco_secret_area *secret_area; + unsigned long secret_area_size; + + if (efi.coco_secret == EFI_INVALID_TABLE_ADDR) + return 0; + + secret_area = early_memremap(efi.coco_secret, sizeof(*secret_area)); + if (!secret_area) { + pr_err("Failed to map confidential computing secret area\n"); + efi.coco_secret = EFI_INVALID_TABLE_ADDR; + return -ENOMEM; + } + + secret_area_size = sizeof(*secret_area) + secret_area->size; + memblock_reserve(efi.coco_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 847f33ffc4ae..07e17ad225a6 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -526,6 +526,7 @@ 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_COCO_SECRET_AREA_GUID, &efi.coco_secret, "CocoSecret" }, {}, }; @@ -613,6 +614,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables, efi_tpm_eventlog_init(); + efi_coco_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 9021dd521302..e86600af5dfd 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -550,6 +550,7 @@ 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 coco_secret; /* Confidential computing secret table */ efi_get_time_t *get_time; efi_set_time_t *set_time; @@ -1189,6 +1190,8 @@ extern int efi_tpm_final_log_size; extern unsigned long rci2_table_phys; +extern int efi_coco_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 Aug 9 19:01:57 2021 Content-Type: text/plain; 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Mon, 9 Aug 2021 19:02:03 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E095011206E; Mon, 9 Aug 2021 19:02:02 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 9 Aug 2021 19:02:02 +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 , "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: [PATCH 3/3] virt: Add sev_secret module to expose confidential computing secrets Date: Mon, 9 Aug 2021 19:01:57 +0000 Message-Id: <20210809190157.279332-4-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210809190157.279332-1-dovmurik@linux.ibm.com> References: <20210809190157.279332-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Py4lGVxRo2So-NXPxvZAfroNrubvN_o4 X-Proofpoint-ORIG-GUID: VDY84jtaeMVf7OACIZXuDiOMQfuy0KS1 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-09_07:2021-08-06,2021-08-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 clxscore=1015 mlxlogscore=999 bulkscore=0 mlxscore=0 impostorscore=0 priorityscore=1501 spamscore=0 adultscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108090131 Precedence: bulk List-ID: The new sev_secret module exposes the confidential computing (coco) secret area via securityfs interface. When the module is loaded (and securityfs is mounted, typically under /sys/kernel/security), a "coco/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 "coco/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 | 3 + drivers/virt/Makefile | 1 + drivers/virt/coco/sev_secret/Kconfig | 11 + drivers/virt/coco/sev_secret/Makefile | 2 + drivers/virt/coco/sev_secret/sev_secret.c | 313 ++++++++++++++++++++++ 5 files changed, 330 insertions(+) create mode 100644 drivers/virt/coco/sev_secret/Kconfig create mode 100644 drivers/virt/coco/sev_secret/Makefile create mode 100644 drivers/virt/coco/sev_secret/sev_secret.c diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig index 8061e8ef449f..6f73672f593f 100644 --- a/drivers/virt/Kconfig +++ b/drivers/virt/Kconfig @@ -36,4 +36,7 @@ source "drivers/virt/vboxguest/Kconfig" source "drivers/virt/nitro_enclaves/Kconfig" source "drivers/virt/acrn/Kconfig" + +source "drivers/virt/coco/sev_secret/Kconfig" + endif diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile index 3e272ea60cd9..2a7d472478bd 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-$(CONFIG_AMD_SEV_SECRET) += coco/sev_secret/ diff --git a/drivers/virt/coco/sev_secret/Kconfig b/drivers/virt/coco/sev_secret/Kconfig new file mode 100644 index 000000000000..76cfb4f405e0 --- /dev/null +++ b/drivers/virt/coco/sev_secret/Kconfig @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: GPL-2.0-only +config AMD_SEV_SECRET + tristate "AMD SEV secret area securityfs support" + depends on AMD_MEM_ENCRYPT && EFI + select SECURITYFS + help + This is a driver for accessing the AMD SEV secret area via + securityfs. + + To compile this driver as a module, choose M here. + The module will be called sev_secret. diff --git a/drivers/virt/coco/sev_secret/Makefile b/drivers/virt/coco/sev_secret/Makefile new file mode 100644 index 000000000000..dca0ed3f8f94 --- /dev/null +++ b/drivers/virt/coco/sev_secret/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_AMD_SEV_SECRET) += sev_secret.o diff --git a/drivers/virt/coco/sev_secret/sev_secret.c b/drivers/virt/coco/sev_secret/sev_secret.c new file mode 100644 index 000000000000..d9a60166b142 --- /dev/null +++ b/drivers/virt/coco/sev_secret/sev_secret.c @@ -0,0 +1,313 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * sev_secret module + * + * Copyright (C) 2021 IBM Corporation + * Author: Dov Murik + */ + +/** + * DOC: sev_secret: Allow reading confidential computing (coco) secret area via + * securityfs interface. + * + * When the module is loaded (and securityfs is mounted, typically under + * /sys/kernel/security), a "coco/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. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#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 *coco_dir; + struct dentry *fs_dir; + struct dentry *fs_files[SEV_SECRET_NUM_FILES]; + struct linux_efi_coco_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_coco_secret_area *secret_area; + u32 secret_area_size; + + if (efi.coco_secret == EFI_INVALID_TABLE_ADDR) { + pr_err("Secret area address is not available\n"); + return -EINVAL; + } + + secret_area = memremap(efi.coco_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.coco_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; + + securityfs_remove(s->coco_dir); + s->coco_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->coco_dir = NULL; + s->fs_dir = NULL; + memset(s->fs_files, 0, sizeof(s->fs_files)); + + dent = securityfs_create_dir("coco", NULL); + if (IS_ERR(dent)) { + pr_err("Error creating coco securityfs directory entry err=%ld\n", PTR_ERR(dent)); + return PTR_ERR(dent); + } + s->coco_dir = dent; + + dent = securityfs_create_dir("sev_secret", s->coco_dir); + if (IS_ERR(dent)) { + pr_err("Error creating SEV secret securityfs directory entry err=%ld\n", + 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");