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Shutemov" , Andi Kleen , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, Brijesh Singh Subject: [PATCH Part1 v5 37/38] virt: sevguest: Add support to derive key Date: Fri, 20 Aug 2021 10:19:32 -0500 Message-Id: <20210820151933.22401-38-brijesh.singh@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210820151933.22401-1-brijesh.singh@amd.com> References: <20210820151933.22401-1-brijesh.singh@amd.com> Content-Type: text/plain X-ClientProxiedBy: SA9P223CA0002.NAMP223.PROD.OUTLOOK.COM (2603:10b6:806:26::7) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from sbrijesh-desktop.amd.com (165.204.77.1) by SA9P223CA0002.NAMP223.PROD.OUTLOOK.COM (2603:10b6:806:26::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4436.19 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?saSts6K+BUVJPIo4RaUDcZxiNVrfkzcWRIoGdkfFy9a6q3WMho+uoz7IBmgD?= =?us-ascii?Q?xeqbEfRzgAzWT16FjKWFMwVfrirhTfdmJCx9ZvPDH/50b1oG37LCjYlqM2tt?= =?us-ascii?Q?CDqXW/A/NTA6+X4yFToCZ9tVyIjQL681FmzxhcsCSu7T/m+b2bQ7JuNgOHpN?= =?us-ascii?Q?fl065nm2bH09yna5uqoBLAXsOKrP+kBghE/cx3EO1mpL3PhkklKc/wtlJu9+?= =?us-ascii?Q?euCaWIYl12eiotUr94iFOkm+HmtD205vsOeL1h1tLo2wk1zE1RQGskCAuFDi?= =?us-ascii?Q?XomyGGKgUpFzSzniURi0xE77lvPgv3NJ6DM25cJgSdodjb6wveZZedoILLIA?= =?us-ascii?Q?FP4gevg4RQsrUlPGZXAAKkGq/39wmLLmtrq/TfiotZIvlHpARSahQ46DL4WX?= =?us-ascii?Q?yC1gdm35M6kWjWQrExZ/9mtwCh5/+nenVuXsKgMGdsiKMPOAGl27E/Au72Qf?= =?us-ascii?Q?p/i8ibFdTQrMnRtwh0t5uJmb2hwXycxEMZ+BqTdK3Zx2+EcqhZmQyWgCElh6?= =?us-ascii?Q?kbuoD+VzElpCpSKfTJobhs/qVCqIkXPmARfRTvhlJPuLCgv8Wml9PeN2HnJ/?= =?us-ascii?Q?eMsnx1n3bZ6bkqdeDrzIP+zK616DxIdEbtJ377Q3QH05cdmZ8ighgYsgJj30?= =?us-ascii?Q?iQ5ffONcWdueJddD2KS0C0yVW316JkOBEdtTV93WBALpUcp8+11G6VmMRdWa?= =?us-ascii?Q?UKmHPDlUvm/L4k0YCrRONDv70OhAmhoHNtc29oeaJmnd7f0umftXbJiylA8D?= =?us-ascii?Q?Gt8Af+usj0ZF9jfGZN9hQsitlwD4Cg4eI+rlS72eUVprTvPMkyCJfPACztkw?= =?us-ascii?Q?44FT9Rf0TpwtVQbCS8OdpqKEsgQnbGgBrCjTHerSnRKCVMuPc0eOJ6qgH5aO?= =?us-ascii?Q?Gvg2YrxnSD0B8g/FAEx7hJ3OPTzpEPPvROEwp6joXfPeEaxQaYvo23Y5fzBX?= =?us-ascii?Q?EeXjlhgNIUs55TSBlqMK3SagN8gA0bjj6yt30N+c3LUqxCArWOl4CifTiD7c?= =?us-ascii?Q?Fzu+hX/wNIoHxiDu736M7Hy4VbCmxLjb3N/56HNXhpvHITRDa9mhPrqDzbGb?= =?us-ascii?Q?Lq1WDFGatQvyqNtDMbsNRB76Z5CvC5LEun495tkD1/wuSvYFJS109KEF/MXs?= =?us-ascii?Q?OailtzOL1SEli7mZX7NUKjtUyjgMOKOv7fGktnuu55Isg0Gb35OMtEE2aUF4?= =?us-ascii?Q?kRAqMSLFLx4V5UxPdKonRsNo6vKF0NXFyxc8nZTuflF2yE3iGO5gQZGmUkqC?= =?us-ascii?Q?wi+4F0uDpCXtCWJndVg/uk5eYE0M1AkN7r50LpE0hW9MdAI9j/PYlPshTIRE?= =?us-ascii?Q?SeqT3altqYof3HaSGSDAN5jo?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: dd22eaf7-e52e-4294-e935-08d963ee32c0 X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2718.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Aug 2021 15:21:35.6014 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: rJAW8pCcWsQ2lyqobr1uXGAjvWwzVceZYhv54jV9XAl44v1R1Ive59FkZgsklzE1hgovsCu1OCA4ohFuNFIy1g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR12MB2637 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 | 18 ++++++++++ drivers/virt/coco/sevguest/sevguest.c | 48 +++++++++++++++++++++++++++ include/uapi/linux/sev-guest.h | 24 ++++++++++++++ 3 files changed, 90 insertions(+) diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst index 52d5915037ef..25446670d816 100644 --- a/Documentation/virt/coco/sevguest.rst +++ b/Documentation/virt/coco/sevguest.rst @@ -67,3 +67,21 @@ provided by the SEV-SNP firmware to query the attestation report. On success, the snp_report_resp.data will contains the report. The report format is 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. diff --git a/drivers/virt/coco/sevguest/sevguest.c b/drivers/virt/coco/sevguest/sevguest.c index d029a98ad088..621b1c5a9cfc 100644 --- a/drivers/virt/coco/sevguest/sevguest.c +++ b/drivers/virt/coco/sevguest/sevguest.c @@ -303,6 +303,50 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_user_guest_reque return rc; } +static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_user_guest_request *arg) +{ + struct snp_guest_crypto *crypto = snp_dev->crypto; + struct snp_derived_key_resp *resp; + struct snp_derived_key_req req; + int rc, resp_len; + + if (!arg->req_data || !arg->resp_data) + return -EINVAL; + + /* Copy the request payload from the 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; + resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!resp) + return -ENOMEM; + + /* Issue the command to get the attestation report */ + rc = handle_guest_request(snp_dev, req.msg_version, SNP_MSG_KEY_REQ, + &req.data, sizeof(req.data), resp->data, resp_len, + &arg->fw_err); + if (rc) + goto e_free; + + /* Copy the response payload to userspace */ + if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp))) + rc = -EFAULT; + +e_free: + kfree(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); @@ -320,6 +364,10 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long 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 e8cfd15133f3..621a9167df7a 100644 --- a/include/uapi/linux/sev-guest.h +++ b/include/uapi/linux/sev-guest.h @@ -36,9 +36,33 @@ struct snp_user_guest_request { __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_user_guest_request) +/* Get a derived key from the root */ +#define SNP_GET_DERIVED_KEY _IOWR(SNP_GUEST_REQ_IOC_TYPE, 0x1, struct snp_user_guest_request) + #endif /* __UAPI_LINUX_SEV_GUEST_H_ */ -- 2.17.1