s390/uvdevice: Add 'List Secrets' UVC

Userspace can call the List Secrets Ultravisor Call
using IOCTLs on the uvdevice. The List Secrets UV call lists the
identifier of the secrets in the UV secret store.

The uvdevice is merely transporting the request from userspace to
Ultravisor. It's neither checking nor manipulating the request or
response data.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20230615100533.3996107-5-seiden@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <20230615100533.3996107-5-seiden@linux.ibm.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c
index 7221e987703a..70502c4ec290 100644
--- a/drivers/s390/char/uvdevice.c
+++ b/drivers/s390/char/uvdevice.c
@@ -38,6 +38,7 @@ static const u32 ioctl_nr_to_uvc_bit[] __initconst = {
 	[UVIO_IOCTL_UVDEV_INFO_NR] = BIT_UVIO_INTERNAL,
 	[UVIO_IOCTL_ATT_NR] = BIT_UVC_CMD_RETR_ATTEST,
 	[UVIO_IOCTL_ADD_SECRET_NR] = BIT_UVC_CMD_ADD_SECRET,
+	[UVIO_IOCTL_LIST_SECRETS_NR] = BIT_UVC_CMD_LIST_SECRETS,
 };
 
 static_assert(ARRAY_SIZE(ioctl_nr_to_uvc_bit) == UVIO_IOCTL_NUM_IOCTLS);
@@ -291,6 +292,54 @@ out:
 	return ret;
 }
 
+/** uvio_list_secrets() - perform a List Secret UVC
+ * @uv_ioctl: ioctl control block
+ *
+ * uvio_list_secrets() performs the List Secret Ultravisor Call. It verifies
+ * that the given userspace argument address is valid and its size is sane.
+ * Every other check is made by the Ultravisor (UV) and won't result in a
+ * negative return value. It builds the request, performs the UV-call, and
+ * copies the result to userspace.
+ *
+ * The argument specifies the location for the result of the UV-Call.
+ *
+ * If the List Secrets UV facility is not present, UV will return invalid
+ * command rc. This won't be fenced in the driver and does not result in a
+ * negative return value.
+ *
+ * Context: might sleep
+ *
+ * Return: 0 on success or a negative error code on error.
+ */
+static int uvio_list_secrets(struct uvio_ioctl_cb *uv_ioctl)
+{
+	void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
+	struct uv_cb_guest_addr uvcb = {
+		.header.len = sizeof(uvcb),
+		.header.cmd = UVC_CMD_LIST_SECRETS,
+	};
+	void *secrets = NULL;
+	int ret = 0;
+
+	if (uv_ioctl->argument_len != UVIO_LIST_SECRETS_LEN)
+		return -EINVAL;
+
+	secrets = kvzalloc(UVIO_LIST_SECRETS_LEN, GFP_KERNEL);
+	if (!secrets)
+		return -ENOMEM;
+
+	uvcb.addr = (u64)secrets;
+	uv_call_sched(0, (u64)&uvcb);
+	uv_ioctl->uv_rc = uvcb.header.rc;
+	uv_ioctl->uv_rrc = uvcb.header.rrc;
+
+	if (copy_to_user(user_buf_arg, secrets, UVIO_LIST_SECRETS_LEN))
+		ret = -EFAULT;
+
+	kvfree(secrets);
+	return ret;
+}
+
 static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp,
 				     unsigned long cmd)
 {
@@ -338,6 +387,9 @@ static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case UVIO_IOCTL_ADD_SECRET_NR:
 		ret = uvio_add_secret(&uv_ioctl);
 		break;
+	case UVIO_IOCTL_LIST_SECRETS_NR:
+		ret = uvio_list_secrets(&uv_ioctl);
+		break;
 	default:
 		ret = -ENOIOCTLCMD;
 		break;