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David Alan Gilbert" , , , , Brijesh Singh Subject: [PATCH v7 45/45] virt: sevguest: Add support to get extended report Date: Wed, 10 Nov 2021 16:07:31 -0600 Message-ID: <20211110220731.2396491-46-brijesh.singh@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211110220731.2396491-1-brijesh.singh@amd.com> References: <20211110220731.2396491-1-brijesh.singh@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 4bfe6bd8-174d-4740-ef86-08d9a496b7e1 X-MS-TrafficTypeDiagnostic: DM5PR12MB2568: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:2331; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(4636009)(46966006)(36840700001)(4326008)(508600001)(7696005)(36756003)(54906003)(110136005)(8936002)(8676002)(83380400001)(426003)(86362001)(336012)(44832011)(16526019)(6666004)(2616005)(70586007)(186003)(26005)(47076005)(70206006)(356005)(5660300002)(7406005)(36860700001)(81166007)(7416002)(2906002)(82310400003)(1076003)(316002)(2101003)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Nov 2021 22:09:08.5873 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 4bfe6bd8-174d-4740-ef86-08d9a496b7e1 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT006.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR12MB2568 Version 2 of GHCB specification defines Non-Automatic-Exit(NAE) to get the extended guest report. It is similar to the SNP_GET_REPORT ioctl. The main difference is related to the additional data that will be returned. The additional data returned is a certificate blob that can be used by the SNP guest user. The certificate blob layout is defined in the GHCB specification. The driver simply treats the blob as a opaque data and copies it to userspace. Signed-off-by: Brijesh Singh --- Documentation/virt/coco/sevguest.rst | 23 +++++++ drivers/virt/coco/sevguest/sevguest.c | 93 +++++++++++++++++++++++++++ include/uapi/linux/sev-guest.h | 13 ++++ 3 files changed, 129 insertions(+) diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst index 0bd9a65e0370..5217a9176fb9 100644 --- a/Documentation/virt/coco/sevguest.rst +++ b/Documentation/virt/coco/sevguest.rst @@ -86,6 +86,29 @@ on the various fields passed in the key derivation request. On success, the snp_derived_key_resp.data will contains the derived key value. See the SEV-SNP specification for further details. + +2.3 SNP_GET_EXT_REPORT +---------------------- +:Technology: sev-snp +:Type: guest ioctl +:Parameters (in/out): struct snp_ext_report_req +:Returns (out): struct snp_report_resp on success, -negative on error + +The SNP_GET_EXT_REPORT ioctl is similar to the SNP_GET_REPORT. The difference is +related to the additional certificate data that is returned with the report. +The certificate data returned is being provided by the hypervisor through the +SNP_SET_EXT_CONFIG. + +The ioctl uses the SNP_GUEST_REQUEST (MSG_REPORT_REQ) command provided by the SEV-SNP +firmware to get the attestation report. + +On success, the snp_ext_report_resp.data will contain the attestation report +and snp_ext_report_req.certs_address will contain the certificate blob. If the +length of the blob is smaller than expected then snp_ext_report_req.certs_len will +be updated with the expected value. + +See GHCB specification for further detail on how to parse the certificate blob. + Reference --------- diff --git a/drivers/virt/coco/sevguest/sevguest.c b/drivers/virt/coco/sevguest/sevguest.c index bece6856573e..15e37f3a0bb1 100644 --- a/drivers/virt/coco/sevguest/sevguest.c +++ b/drivers/virt/coco/sevguest/sevguest.c @@ -41,6 +41,7 @@ struct snp_guest_dev { struct device *dev; struct miscdevice misc; + void *certs_data; struct snp_guest_crypto *crypto; struct snp_guest_msg *request, *response; struct snp_secrets_page_layout *layout; @@ -438,6 +439,88 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque return rc; } +static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) +{ + struct snp_guest_crypto *crypto = snp_dev->crypto; + struct snp_ext_report_req req; + struct snp_report_resp *resp; + int ret, npages = 0, resp_len; + + if (!arg->req_data || !arg->resp_data) + return -EINVAL; + + /* Copy the request payload from userspace */ + if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) + return -EFAULT; + + /* Message version must be non-zero */ + if (!req.data.msg_version) + return -EINVAL; + + if (req.certs_len) { + if (req.certs_len > SEV_FW_BLOB_MAX_SIZE || + !IS_ALIGNED(req.certs_len, PAGE_SIZE)) + return -EINVAL; + } + + if (req.certs_address && req.certs_len) { + if (!access_ok(req.certs_address, req.certs_len)) + return -EFAULT; + + /* + * Initialize the intermediate buffer with all zero's. This buffer + * is used in the guest request message to get the certs blob from + * the host. If host does not supply any certs in it, then copy + * zeros to indicate that certificate data was not provided. + */ + memset(snp_dev->certs_data, 0, req.certs_len); + + npages = req.certs_len >> PAGE_SHIFT; + } + + /* + * The intermediate response buffer is used while decrypting the + * response payload. Make sure that it has enough space to cover the + * authtag. + */ + resp_len = sizeof(resp->data) + crypto->a_len; + resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!resp) + return -ENOMEM; + + snp_dev->input.data_npages = npages; + ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, req.data.msg_version, + SNP_MSG_REPORT_REQ, &req.data.user_data, + sizeof(req.data.user_data), resp->data, resp_len, &arg->fw_err); + + /* If certs length is invalid then copy the returned length */ + if (arg->fw_err == SNP_GUEST_REQ_INVALID_LEN) { + req.certs_len = snp_dev->input.data_npages << PAGE_SHIFT; + + if (copy_to_user((void __user *)arg->req_data, &req, sizeof(req))) + ret = -EFAULT; + } + + if (ret) + goto e_free; + + /* Copy the certificate data blob to userspace */ + if (req.certs_address && req.certs_len && + copy_to_user((void __user *)req.certs_address, snp_dev->certs_data, + req.certs_len)) { + ret = -EFAULT; + goto e_free; + } + + /* Copy the response payload to userspace */ + if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp))) + ret = -EFAULT; + +e_free: + kfree(resp); + return ret; +} + static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) { struct snp_guest_dev *snp_dev = to_snp_dev(file); @@ -466,6 +549,9 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long case SNP_GET_DERIVED_KEY: ret = get_derived_key(snp_dev, &input); break; + case SNP_GET_EXT_REPORT: + ret = get_ext_report(snp_dev, &input); + break; default: break; } @@ -594,6 +680,10 @@ static int __init snp_guest_probe(struct platform_device *pdev) if (!snp_dev->response) goto e_fail; + snp_dev->certs_data = alloc_shared_pages(SEV_FW_BLOB_MAX_SIZE); + if (!snp_dev->certs_data) + goto e_fail; + ret = -EIO; snp_dev->crypto = init_crypto(snp_dev, snp_dev->vmpck, VMPCK_KEY_LEN); if (!snp_dev->crypto) @@ -607,6 +697,7 @@ static int __init snp_guest_probe(struct platform_device *pdev) /* initial the input address for guest request */ snp_dev->input.req_gpa = __pa(snp_dev->request); snp_dev->input.resp_gpa = __pa(snp_dev->response); + snp_dev->input.data_gpa = __pa(snp_dev->certs_data); ret = misc_register(misc); if (ret) @@ -617,6 +708,7 @@ static int __init snp_guest_probe(struct platform_device *pdev) e_fail: iounmap(layout); + free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); @@ -629,6 +721,7 @@ static int __exit snp_guest_remove(struct platform_device *pdev) free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); + free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); deinit_crypto(snp_dev->crypto); misc_deregister(&snp_dev->misc); diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h index f6d9c136ff4d..3f6a9d694a47 100644 --- a/include/uapi/linux/sev-guest.h +++ b/include/uapi/linux/sev-guest.h @@ -57,6 +57,16 @@ struct snp_derived_key_resp { __u8 data[64]; }; +struct snp_ext_report_req { + struct snp_report_req data; + + /* where to copy the certificate blob */ + __u64 certs_address; + + /* length of the certificate blob */ + __u32 certs_len; +}; + #define SNP_GUEST_REQ_IOC_TYPE 'S' /* Get SNP attestation report */ @@ -65,4 +75,7 @@ struct snp_derived_key_resp { /* Get a derived key from the root */ #define SNP_GET_DERIVED_KEY _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x1, struct snp_guest_request_ioctl) +/* Get SNP extended report as defined in the GHCB specification version 2. */ +#define SNP_GET_EXT_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x2, struct snp_guest_request_ioctl) + #endif /* __UAPI_LINUX_SEV_GUEST_H_ */ -- 2.25.1