diff options
author | Brijesh Singh <brijesh.singh@amd.com> | 2022-02-24 19:56:23 +0300 |
---|---|---|
committer | Borislav Petkov <bp@suse.de> | 2022-04-07 17:47:12 +0300 |
commit | 68de0b2f938642079c0c853b219bdb88c4dc4d13 (patch) | |
tree | 47b4e86cd61144bd5fcba09a040c7e958828a31c /drivers/virt/coco | |
parent | fce96cf0443083e37455eff8f78fd240c621dae3 (diff) | |
download | linux-68de0b2f938642079c0c853b219bdb88c4dc4d13.tar.xz |
virt: sevguest: Add support to derive key
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 chooses, such as a
sealing key or communicating with the external entities.
See SEV-SNP firmware spec for more information.
[ bp: No need to memset "req" - it will get overwritten. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-45-brijesh.singh@amd.com
Diffstat (limited to 'drivers/virt/coco')
-rw-r--r-- | drivers/virt/coco/sevguest/sevguest.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/drivers/virt/coco/sevguest/sevguest.c b/drivers/virt/coco/sevguest/sevguest.c index beda93cdeb4f..393777b72e5e 100644 --- a/drivers/virt/coco/sevguest/sevguest.c +++ b/drivers/virt/coco/sevguest/sevguest.c @@ -391,6 +391,48 @@ e_free: return rc; } +static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) +{ + struct snp_guest_crypto *crypto = snp_dev->crypto; + struct snp_derived_key_resp resp = {0}; + struct snp_derived_key_req req; + int rc, resp_len; + /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ + u8 buf[64 + 16]; + + lockdep_assert_held(&snp_cmd_mutex); + + if (!arg->req_data || !arg->resp_data) + 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; + if (sizeof(buf) < resp_len) + return -ENOMEM; + + if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req))) + return -EFAULT; + + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg->msg_version, + SNP_MSG_KEY_REQ, &req, sizeof(req), buf, resp_len, + &arg->fw_err); + if (rc) + return rc; + + memcpy(resp.data, buf, sizeof(resp.data)); + if (copy_to_user((void __user *)arg->resp_data, &resp, sizeof(resp))) + rc = -EFAULT; + + /* The response buffer contains the sensitive data, explicitly clear it. */ + memzero_explicit(buf, sizeof(buf)); + memzero_explicit(&resp, sizeof(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); @@ -420,6 +462,9 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long case SNP_GET_REPORT: ret = get_report(snp_dev, &input); break; + case SNP_GET_DERIVED_KEY: + ret = get_derived_key(snp_dev, &input); + break; default: break; } |