Messages in this thread | | | Date | Wed, 22 Feb 2023 10:50:12 -0600 | Subject | Re: [PATCH RFC v8 27/56] crypto: ccp: Add the SNP_{SET,GET}_EXT_CONFIG command | From | Tom Lendacky <> |
| |
On 2/22/23 06:32, Zhi Wang wrote: > On Mon, 20 Feb 2023 12:38:18 -0600 > Michael Roth <michael.roth@amd.com> wrote: > >> From: Brijesh Singh <brijesh.singh@amd.com> >> >> 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@amd.com> >> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> >> Signed-off-by: Michael Roth <michael.roth@amd.com> >> --- >> 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; >> +}
| |