SMB3: Allow SMB3 FSCTL queries to be sent to server from tools

For debugging purposes we often have to be able to query
additional information only available via SMB3 FSCTL
from the server from user space tools (e.g. like
cifs-utils's smbinfo).  See MS-FSCC and MS-SMB2 protocol
specifications for more details.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/smb2ops.c

@@ -1330,7 +1330,8 @@ smb2_ioctl_query_info(const unsigned int xid,
 	struct smb_query_info __user *pqi;
 	int rc = 0;
 	int flags = 0;
-	struct smb2_query_info_rsp *rsp = NULL;
+	struct smb2_query_info_rsp *qi_rsp = NULL;
+	struct smb2_ioctl_rsp *io_rsp = NULL;
 	void *buffer = NULL;
 	struct smb_rqst rqst[3];
 	int resp_buftype[3];
@@ -1340,6 +1341,7 @@ smb2_ioctl_query_info(const unsigned int xid,
 	u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
 	struct cifs_fid fid;
 	struct kvec qi_iov[1];
+	struct kvec io_iov[SMB2_IOCTL_IOV_SIZE];
 	struct kvec close_iov[1];
 
 	memset(rqst, 0, sizeof(rqst));
@@ -1394,8 +1396,16 @@ smb2_ioctl_query_info(const unsigned int xid,
 		/* Can eventually relax perm check since server enforces too */
 		if (!capable(CAP_SYS_ADMIN))
 			rc = -EPERM;
-		else  /* TBD: Add code to compound FSCTL */
-			rc = -EOPNOTSUPP;
+		else  {
+			memset(&io_iov, 0, sizeof(io_iov));
+			rqst[1].rq_iov = io_iov;
+			rqst[1].rq_nvec = SMB2_IOCTL_IOV_SIZE;
+
+			rc = SMB2_ioctl_init(tcon, &rqst[1],
+					     COMPOUND_FID, COMPOUND_FID,
+					     qi.info_type, true, NULL,
+					     0);
+		}
 	} else if (qi.flags == PASSTHRU_QUERY_INFO) {
 		memset(&qi_iov, 0, sizeof(qi_iov));
 		rqst[1].rq_iov = qi_iov;
@@ -1430,24 +1440,44 @@ smb2_ioctl_query_info(const unsigned int xid,
 				resp_buftype, rsp_iov);
 	if (rc)
 		goto iqinf_exit;
+	if (qi.flags & PASSTHRU_FSCTL) {
+		pqi = (struct smb_query_info __user *)arg;
+		io_rsp = (struct smb2_ioctl_rsp *)rsp_iov[1].iov_base;
+		if (le32_to_cpu(io_rsp->OutputCount) < qi.input_buffer_length)
+			qi.input_buffer_length = le32_to_cpu(io_rsp->OutputCount);
+		if (copy_to_user(&pqi->input_buffer_length, &qi.input_buffer_length,
+				 sizeof(qi.input_buffer_length))) {
+			rc = -EFAULT;
+			goto iqinf_exit;
+		}
+		if (copy_to_user(pqi + 1, &io_rsp[1], qi.input_buffer_length)) {
+			rc = -EFAULT;
+			goto iqinf_exit;
+		}
+	} else {
 		pqi = (struct smb_query_info __user *)arg;
-	rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
-	if (le32_to_cpu(rsp->OutputBufferLength) < qi.input_buffer_length)
-		qi.input_buffer_length = le32_to_cpu(rsp->OutputBufferLength);
+		qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
+		if (le32_to_cpu(qi_rsp->OutputBufferLength) < qi.input_buffer_length)
+			qi.input_buffer_length = le32_to_cpu(qi_rsp->OutputBufferLength);
 		if (copy_to_user(&pqi->input_buffer_length, &qi.input_buffer_length,
 				 sizeof(qi.input_buffer_length))) {
 			rc = -EFAULT;
 			goto iqinf_exit;
 		}
-	if (copy_to_user(pqi + 1, rsp->Buffer, qi.input_buffer_length)) {
+		if (copy_to_user(pqi + 1, qi_rsp->Buffer, qi.input_buffer_length)) {
 			rc = -EFAULT;
 			goto iqinf_exit;
 		}
+	}
 
  iqinf_exit:
 	kfree(buffer);
 	SMB2_open_free(&rqst[0]);
+	if (qi.flags & PASSTHRU_FSCTL)
+		SMB2_ioctl_free(&rqst[1]);
+	else
 		SMB2_query_info_free(&rqst[1]);
+
 	SMB2_close_free(&rqst[2]);
 	free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
 	free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);