| Message ID | 20220128171804.569796-44-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand |
On Fri, Jan 28, 2022 at 10:19 AM Brijesh Singh <brijesh.singh@amd.com> wrote: > > 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 <brijesh.singh@amd.com> > --- > 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 zeros > + * 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; Can we pull this duplicated code from get_report() into a helper? > + > + 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 >
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_ */
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 <brijesh.singh@amd.com> --- 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(+)