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David Alan Gilbert" , , , , , Brijesh Singh Subject: [PATCH v9 43/43] virt: sevguest: Add support to get extended report Date: Fri, 28 Jan 2022 11:18:04 -0600 Message-ID: <20220128171804.569796-44-brijesh.singh@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220128171804.569796-1-brijesh.singh@amd.com> References: <20220128171804.569796-1-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: a9b5248f-93c1-4de8-b795-08d9e2825872 X-MS-TrafficTypeDiagnostic: MWHPR1201MB0094:EE_ 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)(40470700004)(36840700001)(46966006)(70586007)(47076005)(2616005)(16526019)(186003)(26005)(2906002)(110136005)(86362001)(40460700003)(36860700001)(356005)(81166007)(508600001)(70206006)(7696005)(8676002)(316002)(7416002)(7406005)(4326008)(82310400004)(83380400001)(6666004)(426003)(336012)(8936002)(44832011)(5660300002)(1076003)(54906003)(36756003)(2101003)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jan 2022 17:19:30.6081 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a9b5248f-93c1-4de8-b795-08d9e2825872 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: DM6NAM11FT032.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR1201MB0094 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 | 89 +++++++++++++++++++++++++++ include/uapi/linux/sev-guest.h | 13 ++++ 3 files changed, 125 insertions(+) diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst index aafc9bce9aef..b9fe20e92d06 100644 --- a/Documentation/virt/coco/sevguest.rst +++ b/Documentation/virt/coco/sevguest.rst @@ -90,6 +90,29 @@ on the various fields passed in the key derivation request. On success, the snp_derived_key_resp.data 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 4369e55df9a6..a53854353944 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; @@ -434,6 +435,84 @@ 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 = {0}; + 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; + + 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, arg->msg_version, + SNP_MSG_REPORT_REQ, &req.data, + sizeof(req.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 +545,9 @@ 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 +676,10 @@ 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 +693,7 @@ 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 +704,7 @@ 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 +717,7 @@ 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 bcd00a6d4501..0a47b6627c78 100644 --- a/include/uapi/linux/sev-guest.h +++ b/include/uapi/linux/sev-guest.h @@ -56,6 +56,16 @@ struct snp_guest_request_ioctl { __u64 fw_err; }; +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 */ @@ -64,4 +74,7 @@ struct snp_guest_request_ioctl { /* 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