From: Brijesh Singh <brijesh.singh@xxxxxxx> The SEV-SNP firmware provides the SNP_CONFIG command used to set the system-wide configuration value for SNP guests. The information includes the TCB version string to be reported in guest attestation reports. Version 2 of the GHCB specification adds an NAE (SNP extended guest request) that a guest can use to query the reports that include additional certificates. In both cases, userspace provided additional data is included in the attestation reports. The userspace will use the SNP_SET_EXT_CONFIG command to give the certificate blob and the reported TCB version string at once. Note that the specification defines certificate blob with a specific GUID format; the userspace is responsible for building the proper certificate blob. The ioctl treats it an opaque blob. While it is not defined in the spec, but let's add SNP_GET_EXT_CONFIG command that can be used to obtain the data programmed through the SNP_SET_EXT_CONFIG. Co-developed-by: Alexey Kardashevskiy <aik@xxxxxxx> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx> Co-developed-by: Dionna Glaze <dionnaglaze@xxxxxxxxxx> Signed-off-by: Dionna Glaze <dionnaglaze@xxxxxxxxxx> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx> [mdr: squash in doc patch from Dionna] Signed-off-by: Michael Roth <michael.roth@xxxxxxx> --- Documentation/virt/coco/sev-guest.rst | 27 ++++ drivers/crypto/ccp/sev-dev.c | 173 ++++++++++++++++++++++++++ drivers/crypto/ccp/sev-dev.h | 2 + include/linux/psp-sev.h | 10 ++ include/uapi/linux/psp-sev.h | 17 +++ 5 files changed, 229 insertions(+) diff --git a/Documentation/virt/coco/sev-guest.rst b/Documentation/virt/coco/sev-guest.rst index e828c5326936..7cabf54395e5 100644 --- a/Documentation/virt/coco/sev-guest.rst +++ b/Documentation/virt/coco/sev-guest.rst @@ -151,6 +151,33 @@ The SNP_PLATFORM_STATUS command is used to query the SNP platform status. The status includes API major, minor version and more. See the SEV-SNP specification for further details. +2.5 SNP_SET_EXT_CONFIG +---------------------- +:Technology: sev-snp +:Type: hypervisor ioctl cmd +:Parameters (in): struct sev_data_snp_ext_config +:Returns (out): 0 on success, -negative on error + +The SNP_SET_EXT_CONFIG is used to set the system-wide configuration such as +reported TCB version in the attestation report. The command is similar to +SNP_CONFIG command defined in the SEV-SNP spec. The main difference is the +command also accepts an additional certificate blob defined in the GHCB +specification. + +If the certs_address is zero, then the previous certificate blob will deleted. +For more information on the certificate blob layout, see the GHCB spec +(extended guest request message). + +2.6 SNP_GET_EXT_CONFIG +---------------------- +:Technology: sev-snp +:Type: hypervisor ioctl cmd +:Parameters (in): struct sev_data_snp_ext_config +:Returns (out): 0 on success, -negative on error + +The SNP_GET_EXT_CONFIG is used to query the system-wide configuration set +through the SNP_SET_EXT_CONFIG. + 3. SEV-SNP CPUID Enforcement ============================ diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 0626c0feff9b..4807ddd6ec52 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -1496,6 +1496,10 @@ static int __sev_snp_shutdown_locked(int *error) data.length = sizeof(data); data.iommu_snp_shutdown = 1; + /* Free the memory used for caching the certificate data */ + sev_snp_certs_put(sev->snp_certs); + sev->snp_certs = NULL; + wbinvd_on_all_cpus(); retry: @@ -1834,6 +1838,121 @@ static int sev_ioctl_snp_platform_status(struct sev_issue_cmd *argp) return ret; } +static int sev_ioctl_snp_get_config(struct sev_issue_cmd *argp) +{ + struct sev_device *sev = psp_master->sev_data; + struct sev_user_data_ext_snp_config input; + struct sev_snp_certs *snp_certs; + int ret; + + if (!sev->snp_initialized || !argp->data) + return -EINVAL; + + if (copy_from_user(&input, (void __user *)argp->data, sizeof(input))) + return -EFAULT; + + /* Copy the TCB version programmed through the SET_CONFIG to userspace */ + if (input.config_address) { + if (copy_to_user((void * __user)input.config_address, + &sev->snp_config, sizeof(struct sev_user_data_snp_config))) + return -EFAULT; + } + + snp_certs = sev_snp_certs_get(sev->snp_certs); + + /* Copy the extended certs programmed through the SNP_SET_CONFIG */ + if (input.certs_address && snp_certs) { + if (input.certs_len < snp_certs->len) { + /* Return the certs length to userspace */ + input.certs_len = snp_certs->len; + + ret = -EIO; + goto e_done; + } + + if (copy_to_user((void * __user)input.certs_address, + snp_certs->data, snp_certs->len)) { + ret = -EFAULT; + goto put_exit; + } + } + + ret = 0; + +e_done: + if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) + ret = -EFAULT; + +put_exit: + sev_snp_certs_put(snp_certs); + + return ret; +} + +static int sev_ioctl_snp_set_config(struct sev_issue_cmd *argp, bool writable) +{ + struct sev_device *sev = psp_master->sev_data; + struct sev_user_data_ext_snp_config input; + struct sev_user_data_snp_config config; + struct sev_snp_certs *snp_certs = NULL; + void *certs = NULL; + int ret; + + if (!sev->snp_initialized || !argp->data) + return -EINVAL; + + if (!writable) + return -EPERM; + + if (copy_from_user(&input, (void __user *)argp->data, sizeof(input))) + return -EFAULT; + + /* Copy the certs from userspace */ + if (input.certs_address) { + if (!input.certs_len || !IS_ALIGNED(input.certs_len, PAGE_SIZE)) + return -EINVAL; + + certs = psp_copy_user_blob(input.certs_address, input.certs_len); + if (IS_ERR(certs)) + return PTR_ERR(certs); + } + + /* Issue the PSP command to update the TCB version using the SNP_CONFIG. */ + if (input.config_address) { + if (copy_from_user(&config, + (void __user *)input.config_address, sizeof(config))) { + ret = -EFAULT; + goto e_free; + } + + ret = __sev_do_cmd_locked(SEV_CMD_SNP_CONFIG, &config, &argp->error); + if (ret) + goto e_free; + + memcpy(&sev->snp_config, &config, sizeof(config)); + } + + /* + * If the new certs are passed then cache it else free the old certs. + */ + if (input.certs_len) { + snp_certs = sev_snp_certs_new(certs, input.certs_len); + if (!snp_certs) { + ret = -ENOMEM; + goto e_free; + } + } + + sev_snp_certs_put(sev->snp_certs); + sev->snp_certs = snp_certs; + + return 0; + +e_free: + kfree(certs); + return ret; +} + static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) { void __user *argp = (void __user *)arg; @@ -1888,6 +2007,12 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) case SNP_PLATFORM_STATUS: ret = sev_ioctl_snp_platform_status(&input); break; + case SNP_SET_EXT_CONFIG: + ret = sev_ioctl_snp_set_config(&input, writable); + break; + case SNP_GET_EXT_CONFIG: + ret = sev_ioctl_snp_get_config(&input); + break; default: ret = -EINVAL; goto out; @@ -1936,6 +2061,54 @@ int sev_guest_df_flush(int *error) } EXPORT_SYMBOL_GPL(sev_guest_df_flush); +static void sev_snp_certs_release(struct kref *kref) +{ + struct sev_snp_certs *certs = container_of(kref, struct sev_snp_certs, kref); + + kfree(certs->data); + kfree(certs); +} + +struct sev_snp_certs *sev_snp_certs_new(void *data, u32 len) +{ + struct sev_snp_certs *certs; + + if (!len || !data) + return NULL; + + certs = kzalloc(sizeof(*certs), GFP_KERNEL); + if (!certs) + return NULL; + + certs->data = data; + certs->len = len; + kref_init(&certs->kref); + + return certs; +} +EXPORT_SYMBOL_GPL(sev_snp_certs_new); + +struct sev_snp_certs *sev_snp_certs_get(struct sev_snp_certs *certs) +{ + if (!certs) + return NULL; + + if (!kref_get_unless_zero(&certs->kref)) + return NULL; + + return certs; +} +EXPORT_SYMBOL_GPL(sev_snp_certs_get); + +void sev_snp_certs_put(struct sev_snp_certs *certs) +{ + if (!certs) + return; + + kref_put(&certs->kref, sev_snp_certs_release); +} +EXPORT_SYMBOL_GPL(sev_snp_certs_put); + static void sev_exit(struct kref *ref) { misc_deregister(&misc_dev->misc); diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h index 2c2fe42189a5..71eac493fd56 100644 --- a/drivers/crypto/ccp/sev-dev.h +++ b/drivers/crypto/ccp/sev-dev.h @@ -66,6 +66,8 @@ struct sev_device { bool snp_initialized; struct snp_host_map snp_host_map[MAX_SNP_HOST_MAP_BUFS]; + struct sev_snp_certs *snp_certs; + struct sev_user_data_snp_config snp_config; }; int sev_dev_init(struct psp_device *psp); diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h index 9342cee1a1e6..3c605856ef4f 100644 --- a/include/linux/psp-sev.h +++ b/include/linux/psp-sev.h @@ -16,6 +16,16 @@ #define SEV_FW_BLOB_MAX_SIZE 0x4000 /* 16KB */ +struct sev_snp_certs { + void *data; + u32 len; + struct kref kref; +}; + +struct sev_snp_certs *sev_snp_certs_new(void *data, u32 len); +struct sev_snp_certs *sev_snp_certs_get(struct sev_snp_certs *certs); +void sev_snp_certs_put(struct sev_snp_certs *certs); + /** * SEV platform state */ diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h index b94b3687edbb..b70db9ab7e44 100644 --- a/include/uapi/linux/psp-sev.h +++ b/include/uapi/linux/psp-sev.h @@ -29,6 +29,8 @@ enum { SEV_GET_ID, /* This command is deprecated, use SEV_GET_ID2 */ SEV_GET_ID2, SNP_PLATFORM_STATUS, + SNP_SET_EXT_CONFIG, + SNP_GET_EXT_CONFIG, SEV_MAX, }; @@ -208,6 +210,21 @@ struct sev_user_data_snp_config { __u8 rsvd1[52]; } __packed; +/** + * struct sev_data_snp_ext_config - system wide configuration value for SNP. + * + * @config_address: address of the struct sev_user_data_snp_config or 0 when + * reported_tcb does not need to be updated. + * @certs_address: address of extended guest request certificate chain or + * 0 when previous certificate should be removed on SNP_SET_EXT_CONFIG. + * @certs_len: length of the certs + */ +struct sev_user_data_ext_snp_config { + __u64 config_address; /* In */ + __u64 certs_address; /* In */ + __u32 certs_len; /* In */ +} __packed; + /** * struct sev_issue_cmd - SEV ioctl parameters * -- 2.25.1