On 2/22/23 06:32, Zhi Wang wrote:
On Mon, 20 Feb 2023 12:38:18 -0600
Michael Roth <michael.roth@xxxxxxx> wrote:
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.
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
---
Documentation/virt/coco/sev-guest.rst | 27 ++++++
drivers/crypto/ccp/sev-dev.c | 123 ++++++++++++++++++++++++++
drivers/crypto/ccp/sev-dev.h | 4 +
include/uapi/linux/psp-sev.h | 17 ++++
4 files changed, 171 insertions(+)
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 65e13a562f3b..b56b00ca2cd4 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1481,6 +1481,10 @@ 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 */
+ kfree(sev->snp_certs_data);
+ sev->snp_certs_data = NULL;
+
wbinvd_on_all_cpus();
retry:
@@ -1793,6 +1797,118 @@ 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;
+ int ret;
+
+ if (!sev->snp_initialized || !argp->data)
+ return -EINVAL;
+
+ memset(&input, 0, sizeof(input));
+
+ 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;
+ }
+
+ /* Copy the extended certs programmed through the SNP_SET_CONFIG */
+ if (input.certs_address && sev->snp_certs_data) {
+ if (input.certs_len < sev->snp_certs_len) {
+ /* Return the certs length to userspace */
+ input.certs_len = sev->snp_certs_len;
+
+ ret = -ENOSR;
We should be consistent with the other SEV ioctls that return required
lengths and return -EIO here instead -ENOSR.
Thanks,
Tom
+ goto e_done;
+ }
+
What about if input.certs_len > sev->snp_certs_len? Is it possbile for the
userspace to know the length of data in the buffer? (I guess it might be able
to know the certs len through the blob data, but a comment here would be nice)
+ if (copy_to_user((void * __user)input.certs_address,
+ sev->snp_certs_data, sev->snp_certs_len))
+ return -EFAULT;
+ }
+
+ ret = 0;
+
+e_done:
+ if (copy_to_user((void __user *)argp->data, &input, sizeof(input)))
+ ret = -EFAULT;
+
+ return ret;
+}
