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Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , tony.luck@intel.com, npmccallum@redhat.com, brijesh.ksingh@gmail.com, Brijesh Singh Subject: [PATCH Part1 RFC v4 35/36] virt: sevguest: Add support to derive key Date: Wed, 7 Jul 2021 13:15:05 -0500 Message-Id: <20210707181506.30489-36-brijesh.singh@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210707181506.30489-1-brijesh.singh@amd.com> References: <20210707181506.30489-1-brijesh.singh@amd.com> X-ClientProxiedBy: SA0PR11CA0104.namprd11.prod.outlook.com (2603:10b6:806:d1::19) To BYAPR12MB2711.namprd12.prod.outlook.com (2603:10b6:a03:63::10) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from sbrijesh-desktop.amd.com (165.204.77.1) by SA0PR11CA0104.namprd11.prod.outlook.com (2603:10b6:806:d1::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.19 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: x6joJQOXuDsZ6RYp5TrE4w4WeXP5EmCBEixt/hxI4gKEyXrb9c/nvLVNjYkeqvMsi0CyBOm5Yl8xiHWMJkgpJlc9fpxf44fln2Y2FadDBbZdnDYaNDpO+DB/KoycXVfdgpRJlfRwptAvXhzWtNQIs/x32rDAiFBRjXNPEurq2yuW64Chy2jX7Yl5tDNfshmUf/0Wl8QmtSAUSMMyaId+f9F9AgoT9qhhVYG1RztfLcgN7vM+bw6v03wwpq+zZJqbfmMAFeYHRV0hb2dP29lXaw6yI/rHACF+31os0tGZtLyk5F+5gMufHPUhaKs2SOhfa5OituigBBRSKtl0+586Ft4BknJoWak+glxQqco4BGMf4OlXVu7f/dZJpFF/a2WzVQTYzLybjtGtv9IdgX69Fu6a7LxVf+SkdDYMXAHRb211ZIHcivbMCMC4mXregGfwSL2GApLli5XYY/+31VeDxYEovThiNOeLoac8rWlaWcJ72L7QnOQ3A9KuhFRC0cOng2+FFhlFaNgkubMomKWoogR8otInjebPo4eyIyPMy7TgDJx8rjNIj1CJZw+CnEjDr3YCyGwd+O80GfLqeyCJeJXoJVAWdlZsFbg/lMiZl71a68A8WTlkTUqKtY6twGmhut3/zNd3qJJ6aJIZj8N3d3wfXp1Ay5zEJXsmChXskPI0AFrYX/054heGc9NOf132dlApOBzI8a61PhDjokuY/SP5UNDiiQp3oDmGDr98LpdPqBZJ9bGKbZBXZm7VK3o8W1dqjQHhhqyUXHwqTFDOdnZCGlHOSi8+7dWKs6/OMcwbr3Rm6todb1u89mxkAE+MOLufiHwJXNISxAOldiIlneLdHiJi0RL4TUutwW9aXSvWVYp5E5wdj4xMiQ+oSthTDWSNh6Lii+QcsAHJgcMKTkpckg0DOAx560VVDnDf1e1+4mw3juERPmOUhRDJV8vBrAd7wgkU0j6Xn+4sw2OrHrQTC7yV/CI31E2jwGFB7SiIqpORVXhc271K4YD3+eO9U5gL1PGYjK5hC93vGQcZWH1sTjQ8eZolpyNq10QiOE9eptGLOoL/r0ySZFAxtB/H5Gh6jOIw1rCBv+9UR7G3KBhuAein9P8AqNdfhXYe7VRmgxU73t3Wj54E0z8ucHNkr5PPVIxXInxhGKOWFm1pXavuGXiuMfNt9b00gWq6bc/Ocw9vtwfBNVAbW2epwF2ahxmykV0DES+w1A2uzhUypNjCIyJirPZmZ4UCeYG32RVinjbB1hXDoAfJ/EV9MzktVWpbq/IY1BXRnw84Qc/ffPQX9p6t5rBN68BQHSVM4XZ4oK52UIEP1BqknX+RIYDh X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2112b32f-7620-48c1-6a87-08d9417368a5 X-MS-Exchange-CrossTenant-AuthSource: BYAPR12MB2711.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2021 18:16:58.4460 (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: OvYpKSAjJuph2bQ0VjXhid9EUr/KNOjPeQlkvVBfvGYXZ8RlF5lPxmEbh97FNPmZkSg/60qZ4qTi6lJi91aEPA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR12MB3527 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org 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 f3f86f9b5b22..2f20db80490a 100644 --- a/drivers/virt/coco/sevguest/sevguest.c +++ b/drivers/virt/coco/sevguest/sevguest.c @@ -304,6 +304,50 @@ 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); @@ -321,6 +365,10 @@ 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_ */