SMB2 FSCTL and IOCTL worker function

This worker function is needed to send SMB2 fsctl
(and ioctl) requests including:

validating negotiation info (secure negotiate)
querying the servers network interfaces
copy offload (refcopy)

Followon patches for the above three will use this.
This patch also does general validation of the response.

In the future, as David Disseldorp notes, for the copychunk ioctl
case, we will want to enhance the response processing to allow
returning the chunk request limits to the caller (even
though the server returns an error, in that case we would
return data that the caller could use - see 2.2.32.1).

See MS-SMB2 Section 2.2.31 for more details on format of fsctl.

Acked-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 0de6a82e2465..c0d102615d0a 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -997,6 +997,122 @@ creat_exit:
 	return rc;
 }
 
+/*
+ *	SMB2 IOCTL is used for both IOCTLs and FSCTLs
+ */
+int
+SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
+	   u64 volatile_fid, u32 opcode, bool is_fsctl, char *in_data,
+	   u32 indatalen, char **out_data, u32 *plen /* returned data len */)
+{
+	struct smb2_ioctl_req *req;
+	struct smb2_ioctl_rsp *rsp;
+	struct TCP_Server_Info *server;
+	struct cifs_ses *ses = tcon->ses;
+	struct kvec iov[2];
+	int resp_buftype;
+	int num_iovecs;
+	int rc = 0;
+
+	cifs_dbg(FYI, "SMB2 IOCTL\n");
+
+	/* zero out returned data len, in case of error */
+	if (plen)
+		*plen = 0;
+
+	if (ses && (ses->server))
+		server = ses->server;
+	else
+		return -EIO;
+
+	rc = small_smb2_init(SMB2_IOCTL, tcon, (void **) &req);
+	if (rc)
+		return rc;
+
+	req->CtlCode = cpu_to_le32(opcode);
+	req->PersistentFileId = persistent_fid;
+	req->VolatileFileId = volatile_fid;
+
+	if (indatalen) {
+		req->InputCount = cpu_to_le32(indatalen);
+		/* do not set InputOffset if no input data */
+		req->InputOffset =
+		       cpu_to_le32(offsetof(struct smb2_ioctl_req, Buffer) - 4);
+		iov[1].iov_base = in_data;
+		iov[1].iov_len = indatalen;
+		num_iovecs = 2;
+	} else
+		num_iovecs = 1;
+
+	req->OutputOffset = 0;
+	req->OutputCount = 0; /* MBZ */
+
+	/*
+	 * Could increase MaxOutputResponse, but that would require more
+	 * than one credit. Windows typically sets this smaller, but for some
+	 * ioctls it may be useful to allow server to send more. No point
+	 * limiting what the server can send as long as fits in one credit
+	 */
+	req->MaxOutputResponse = cpu_to_le32(0xFF00); /* < 64K uses 1 credit */
+
+	if (is_fsctl)
+		req->Flags = cpu_to_le32(SMB2_0_IOCTL_IS_FSCTL);
+	else
+		req->Flags = 0;
+
+	iov[0].iov_base = (char *)req;
+	/* 4 for rfc1002 length field */
+	iov[0].iov_len = get_rfc1002_length(req) + 4;
+
+	if (indatalen)
+		inc_rfc1001_len(req, indatalen);
+
+	rc = SendReceive2(xid, ses, iov, num_iovecs, &resp_buftype, 0);
+	rsp = (struct smb2_ioctl_rsp *)iov[0].iov_base;
+
+	if (rc != 0) {
+		if (tcon)
+			cifs_stats_fail_inc(tcon, SMB2_IOCTL_HE);
+		goto ioctl_exit;
+	}
+
+	/* check if caller wants to look at return data or just return rc */
+	if ((plen == NULL) || (out_data == NULL))
+		goto ioctl_exit;
+
+	*plen = le32_to_cpu(rsp->OutputCount);
+
+	/* We check for obvious errors in the output buffer length and offset */
+	if (*plen == 0)
+		goto ioctl_exit; /* server returned no data */
+	else if (*plen > 0xFF00) {
+		cifs_dbg(VFS, "srv returned invalid ioctl length: %d\n", *plen);
+		*plen = 0;
+		rc = -EIO;
+		goto ioctl_exit;
+	}
+
+	if (get_rfc1002_length(rsp) < le32_to_cpu(rsp->OutputOffset) + *plen) {
+		cifs_dbg(VFS, "Malformed ioctl resp: len %d offset %d\n", *plen,
+			le32_to_cpu(rsp->OutputOffset));
+		*plen = 0;
+		rc = -EIO;
+		goto ioctl_exit;
+	}
+
+	*out_data = kmalloc(*plen, GFP_KERNEL);
+	if (*out_data == NULL) {
+		rc = -ENOMEM;
+		goto ioctl_exit;
+	}
+
+	memcpy(*out_data, rsp->hdr.ProtocolId + le32_to_cpu(rsp->OutputOffset),
+	       *plen);
+ioctl_exit:
+	free_rsp_buf(resp_buftype, rsp);
+	return rc;
+}
+
 int
 SMB2_close(const unsigned int xid, struct cifs_tcon *tcon,
 	   u64 persistent_fid, u64 volatile_fid)