From patchwork Thu May 13 06:26:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dov Murik X-Patchwork-Id: 437505 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, URIBL_BLOCKED, 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 B1313C43462 for ; Thu, 13 May 2021 06:27:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9045F6143B for ; Thu, 13 May 2021 06:27:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231311AbhEMG2X (ORCPT ); Thu, 13 May 2021 02:28:23 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49982 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231340AbhEMG2R (ORCPT ); Thu, 13 May 2021 02:28:17 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 14D62jUF131020; Thu, 13 May 2021 02:26:59 -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=atVN1mAwQ8g8XeoMl100jVG91TaBJp4y9kyiYfEfanc=; b=I1Vuie6A5G55fdq2OhgL8uCET8gaWH21YfdCJFpFXFpw0ybnIj/mS2TY8utQvSldgIkK 1BNsawsWhRTefZ1qyJblPjPgH3m6pxn1yuHDNZ9lnbsT9euHEMuFjTkpVCsOmuXGCLLg 4w939VKPtwpiWywkEtaktjLw+zeGcNR+HCs1ORa7nMJ4BuRYoopVYpUoIZ2acjvtm9a4 68jeJTmkNZcPJ2RUzpshSk4m38iUDmCFi5TGJLRbt9OoFGK8yNn068WlhZC/564SSb7t NAUsDlnW1bmdQbjPNDE9v9fdnfp0ZZ+PUWQA4FSmPJmKFbNqZdnRn52UBvs8TUrYTg4s gw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 38gv83k936-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 May 2021 02:26:58 -0400 Received: from m0098413.ppops.net (m0098413.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 14D62t4E131592; Thu, 13 May 2021 02:26:58 -0400 Received: from ppma02wdc.us.ibm.com (aa.5b.37a9.ip4.static.sl-reverse.com [169.55.91.170]) by mx0b-001b2d01.pphosted.com with ESMTP id 38gv83k931-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 May 2021 02:26:58 -0400 Received: from pps.filterd (ppma02wdc.us.ibm.com [127.0.0.1]) by ppma02wdc.us.ibm.com (8.16.0.43/8.16.0.43) with SMTP id 14D6Cojx024783; Thu, 13 May 2021 06:26:57 GMT Received: from b03cxnp07027.gho.boulder.ibm.com (b03cxnp07027.gho.boulder.ibm.com [9.17.130.14]) by ppma02wdc.us.ibm.com with ESMTP id 38dj99u0dm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 May 2021 06:26:57 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp07027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 14D6Queh19792242 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 13 May 2021 06:26:56 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 17B167805F; Thu, 13 May 2021 06:26:56 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 048E47805C; Thu, 13 May 2021 06:26:55 +0000 (GMT) Received: from localhost.localdomain (unknown [9.2.130.16]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 13 May 2021 06:26:54 +0000 (GMT) From: Dov Murik To: linux-efi@vger.kernel.org Cc: Tobin Feldman-Fitzthum , Tobin Feldman-Fitzthum , Jim Cadden , James Bottomley , Hubertus Franke , Mike Rapoport , Dov Murik , Laszlo Ersek , Ashish Kalra , Brijesh Singh , Tom Lendacky , James Morris , "Serge E. Hallyn" , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 3/3] virt: Add sev_secret module to expose confidential computing secrets Date: Thu, 13 May 2021 06:26:34 +0000 Message-Id: <20210513062634.2481118-4-dovmurik@linux.ibm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210513062634.2481118-1-dovmurik@linux.ibm.com> References: <20210513062634.2481118-1-dovmurik@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: X_olEUDj-U-o3e7c-WyR1mbCgiCjfL9l X-Proofpoint-ORIG-GUID: dOjkf9djzGWn8PuKPO9mYpZMmLqv8xx0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-05-13_03:2021-05-12,2021-05-13 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 priorityscore=1501 impostorscore=0 suspectscore=0 bulkscore=0 lowpriorityscore=0 phishscore=0 mlxlogscore=999 spamscore=0 malwarescore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105130046 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). Cc: Laszlo Ersek Cc: Ashish Kalra Cc: Brijesh Singh Cc: Tom Lendacky Cc: James Bottomley Cc: James Morris Cc: "Serge E. Hallyn" Cc: linux-security-module@vger.kernel.org Cc: linux-kernel@vger.kernel.org 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 | 260 +++++++++++++++++++++++++++ 5 files changed, 276 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..9fff62356e74 --- /dev/null +++ b/drivers/virt/sev_secret/sev_secret.c @@ -0,0 +1,260 @@ +// 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 + * @len: Length of secret entry, including its guid and len fields + * @data: The secret data + */ +struct secret_entry { + efi_guid_t guid; + u32 len; + u8 data[]; +} __attribute((packed)); + +static struct sev_secret the_sev_secret; + +static size_t secret_entry_data_len(struct secret_entry *e) +{ + return e->len - sizeof(*e); +} + +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 inline struct sev_secret *sev_secret_get(void) +{ + return &the_sev_secret; +} + +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--) + if (s->fs_files[i]) + securityfs_remove(s->fs_files[i]); + + if (s->fs_dir) + securityfs_remove(s->fs_dir); + + 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"); + return PTR_ERR(dent); + } + 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; + } + + 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");