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David Alan Gilbert" , , , , Brijesh Singh Subject: [PATCH v6 41/42] virt: sevguest: Add support to derive key Date: Fri, 8 Oct 2021 13:04:52 -0500 Message-ID: <20211008180453.462291-42-brijesh.singh@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211008180453.462291-1-brijesh.singh@amd.com> References: <20211008180453.462291-1-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: 5c329cc3-113b-4fff-5ee0-08d98a86567d X-MS-TrafficTypeDiagnostic: MN2PR12MB4472: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:2582; 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)(36840700001)(46966006)(2906002)(36860700001)(186003)(5660300002)(70586007)(70206006)(86362001)(26005)(8676002)(4326008)(47076005)(7696005)(36756003)(83380400001)(16526019)(2616005)(7416002)(8936002)(81166007)(426003)(316002)(508600001)(1076003)(7406005)(356005)(336012)(110136005)(54906003)(6666004)(82310400003)(44832011)(36900700001)(2101003);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Oct 2021 18:06:22.9394 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5c329cc3-113b-4fff-5ee0-08d98a86567d 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: CO1NAM11FT044.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4472 The SNP_GET_DERIVED_KEY ioctl interface can be used by the SNP guest to ask the firmware to provide a key derived from a root key. The derived key may be used by the guest for any purposes it choose, such as a sealing key or communicating with the external entities. See SEV-SNP firmware spec for more information. Signed-off-by: Brijesh Singh --- Documentation/virt/coco/sevguest.rst | 19 ++++++++++- drivers/virt/coco/sevguest/sevguest.c | 49 +++++++++++++++++++++++++++ include/uapi/linux/sev-guest.h | 24 +++++++++++++ 3 files changed, 91 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst index 002c90946b8a..4b524d1de37c 100644 --- a/Documentation/virt/coco/sevguest.rst +++ b/Documentation/virt/coco/sevguest.rst @@ -64,10 +64,27 @@ The SNP_GET_REPORT ioctl can be used to query the attestation report from the SEV-SNP firmware. The ioctl uses the SNP_GUEST_REQUEST (MSG_REPORT_REQ) command provided by the SEV-SNP firmware to query the attestation report. -On success, the snp_report_resp.data will contains the report. The report +On success, the snp_report_resp.data will contain the report. The report will contain the format described in the SEV-SNP specification. See the SEV-SNP specification for further details. +2.2 SNP_GET_DERIVED_KEY +----------------------- +:Technology: sev-snp +:Type: guest ioctl +:Parameters (in): struct snp_derived_key_req +:Returns (out): struct snp_derived_key_req on success, -negative on error + +The SNP_GET_DERIVED_KEY ioctl can be used to get a key derive from a root key. +The derived key can be used by the guest for any purpose, such as sealing keys +or communicating with external entities. + +The ioctl uses the SNP_GUEST_REQUEST (MSG_KEY_REQ) command provided by the +SEV-SNP firmware to derive the key. See SEV-SNP specification for further details +on the various fileds 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. Reference --------- diff --git a/drivers/virt/coco/sevguest/sevguest.c b/drivers/virt/coco/sevguest/sevguest.c index 2d313fb2ffae..c6ca7d861a3a 100644 --- a/drivers/virt/coco/sevguest/sevguest.c +++ b/drivers/virt/coco/sevguest/sevguest.c @@ -364,6 +364,52 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io return rc; } +static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) +{ + struct snp_guest_crypto *crypto = snp_dev->crypto; + struct snp_derived_key_resp resp = {0}; + struct snp_derived_key_req req; + int rc, resp_len; + u8 buf[89]; + + 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.msg_version) + return -EINVAL; + + /* + * 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; + if (sizeof(buf) < resp_len) + return -ENOMEM; + + /* Issue the command to get the attestation report */ + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, req.msg_version, + SNP_MSG_KEY_REQ, &req.data, sizeof(req.data), buf, resp_len, + &arg->fw_err); + if (rc) + goto e_free; + + /* Copy the response payload to userspace */ + memcpy(resp.data, buf, sizeof(resp.data)); + if (copy_to_user((void __user *)arg->resp_data, &resp, sizeof(resp))) + rc = -EFAULT; + +e_free: + memzero_explicit(buf, sizeof(buf)); + memzero_explicit(&resp, sizeof(resp)); + return rc; +} + static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) { struct snp_guest_dev *snp_dev = to_snp_dev(file); @@ -382,6 +428,9 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long case SNP_GET_REPORT: ret = get_report(snp_dev, &input); break; + case SNP_GET_DERIVED_KEY: + ret = get_derived_key(snp_dev, &input); + break; default: break; } diff --git a/include/uapi/linux/sev-guest.h b/include/uapi/linux/sev-guest.h index eda7edcffda8..f6d9c136ff4d 100644 --- a/include/uapi/linux/sev-guest.h +++ b/include/uapi/linux/sev-guest.h @@ -36,9 +36,33 @@ struct snp_guest_request_ioctl { __u64 fw_err; }; +struct __snp_derived_key_req { + __u32 root_key_select; + __u32 rsvd; + __u64 guest_field_select; + __u32 vmpl; + __u32 guest_svn; + __u64 tcb_version; +}; + +struct snp_derived_key_req { + /* message version number (must be non-zero) */ + __u8 msg_version; + + struct __snp_derived_key_req data; +}; + +struct snp_derived_key_resp { + /* response data, see SEV-SNP spec for the format */ + __u8 data[64]; +}; + #define SNP_GUEST_REQ_IOC_TYPE 'S' /* Get SNP attestation report */ #define SNP_GET_REPORT _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x0, 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) + #endif /* __UAPI_LINUX_SEV_GUEST_H_ */ -- 2.25.1