cifs: when insecure legacy is disabled shrink amount of SMB1 code

Currently much of the smb1 code is built even when
CONFIG_CIFS_ALLOW_INSECURE_LEGACY is disabled.

Move cifssmb.c to only be compiled when insecure legacy is disabled,
and move various SMB1/CIFS helper functions to that ifdef.  Some
functions that were not SMB1/CIFS specific needed to be moved out of
cifssmb.c

This shrinks cifs.ko by more than 10% which is good - but also will
help with the eventual movement of the legacy code to a distinct
module.  Follow on patches can shrink the number of ifdefs by
code restructuring where smb1 code is wedged in functions that
should be calling dialect specific helper functions instead,
and also by moving some functions from file.c/dir.c/inode.c into
smb1 specific c files.

Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 179 insertions, 0 deletions

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 160463e22c95..914a7aaf9fa7 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -21,6 +21,7 @@
 #include <asm/processor.h>
 #include <linux/mempool.h>
 #include <linux/sched/signal.h>
+#include <linux/task_io_accounting_ops.h>
 #include "cifspdu.h"
 #include "cifsglob.h"
 #include "cifsproto.h"
@@ -1638,3 +1639,181 @@ out:
 		return -ERESTARTSYS;
 	return rc;
 }
+
+/*
+ * Discard any remaining data in the current SMB. To do this, we borrow the
+ * current bigbuf.
+ */
+int
+cifs_discard_remaining_data(struct TCP_Server_Info *server)
+{
+	unsigned int rfclen = server->pdu_size;
+	int remaining = rfclen + server->vals->header_preamble_size -
+		server->total_read;
+
+	while (remaining > 0) {
+		int length;
+
+		length = cifs_discard_from_socket(server,
+				min_t(size_t, remaining,
+				      CIFSMaxBufSize + MAX_HEADER_SIZE(server)));
+		if (length < 0)
+			return length;
+		server->total_read += length;
+		remaining -= length;
+	}
+
+	return 0;
+}
+
+static int
+__cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid,
+		     bool malformed)
+{
+	int length;
+
+	length = cifs_discard_remaining_data(server);
+	dequeue_mid(mid, malformed);
+	mid->resp_buf = server->smallbuf;
+	server->smallbuf = NULL;
+	return length;
+}
+
+static int
+cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+	struct cifs_readdata *rdata = mid->callback_data;
+
+	return  __cifs_readv_discard(server, mid, rdata->result);
+}
+
+int
+cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+	int length, len;
+	unsigned int data_offset, data_len;
+	struct cifs_readdata *rdata = mid->callback_data;
+	char *buf = server->smallbuf;
+	unsigned int buflen = server->pdu_size +
+		server->vals->header_preamble_size;
+	bool use_rdma_mr = false;
+
+	cifs_dbg(FYI, "%s: mid=%llu offset=%llu bytes=%u\n",
+		 __func__, mid->mid, rdata->offset, rdata->bytes);
+
+	/*
+	 * read the rest of READ_RSP header (sans Data array), or whatever we
+	 * can if there's not enough data. At this point, we've read down to
+	 * the Mid.
+	 */
+	len = min_t(unsigned int, buflen, server->vals->read_rsp_size) -
+							HEADER_SIZE(server) + 1;
+
+	length = cifs_read_from_socket(server,
+				       buf + HEADER_SIZE(server) - 1, len);
+	if (length < 0)
+		return length;
+	server->total_read += length;
+
+	if (server->ops->is_session_expired &&
+	    server->ops->is_session_expired(buf)) {
+		cifs_reconnect(server, true);
+		return -1;
+	}
+
+	if (server->ops->is_status_pending &&
+	    server->ops->is_status_pending(buf, server)) {
+		cifs_discard_remaining_data(server);
+		return -1;
+	}
+
+	/* set up first two iov for signature check and to get credits */
+	rdata->iov[0].iov_base = buf;
+	rdata->iov[0].iov_len = server->vals->header_preamble_size;
+	rdata->iov[1].iov_base = buf + server->vals->header_preamble_size;
+	rdata->iov[1].iov_len =
+		server->total_read - server->vals->header_preamble_size;
+	cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
+	cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
+		 rdata->iov[1].iov_base, rdata->iov[1].iov_len);
+
+	/* Was the SMB read successful? */
+	rdata->result = server->ops->map_error(buf, false);
+	if (rdata->result != 0) {
+		cifs_dbg(FYI, "%s: server returned error %d\n",
+			 __func__, rdata->result);
+		/* normal error on read response */
+		return __cifs_readv_discard(server, mid, false);
+	}
+
+	/* Is there enough to get to the rest of the READ_RSP header? */
+	if (server->total_read < server->vals->read_rsp_size) {
+		cifs_dbg(FYI, "%s: server returned short header. got=%u expected=%zu\n",
+			 __func__, server->total_read,
+			 server->vals->read_rsp_size);
+		rdata->result = -EIO;
+		return cifs_readv_discard(server, mid);
+	}
+
+	data_offset = server->ops->read_data_offset(buf) +
+		server->vals->header_preamble_size;
+	if (data_offset < server->total_read) {
+		/*
+		 * win2k8 sometimes sends an offset of 0 when the read
+		 * is beyond the EOF. Treat it as if the data starts just after
+		 * the header.
+		 */
+		cifs_dbg(FYI, "%s: data offset (%u) inside read response header\n",
+			 __func__, data_offset);
+		data_offset = server->total_read;
+	} else if (data_offset > MAX_CIFS_SMALL_BUFFER_SIZE) {
+		/* data_offset is beyond the end of smallbuf */
+		cifs_dbg(FYI, "%s: data offset (%u) beyond end of smallbuf\n",
+			 __func__, data_offset);
+		rdata->result = -EIO;
+		return cifs_readv_discard(server, mid);
+	}
+
+	cifs_dbg(FYI, "%s: total_read=%u data_offset=%u\n",
+		 __func__, server->total_read, data_offset);
+
+	len = data_offset - server->total_read;
+	if (len > 0) {
+		/* read any junk before data into the rest of smallbuf */
+		length = cifs_read_from_socket(server,
+					       buf + server->total_read, len);
+		if (length < 0)
+			return length;
+		server->total_read += length;
+	}
+
+	/* how much data is in the response? */
+#ifdef CONFIG_CIFS_SMB_DIRECT
+	use_rdma_mr = rdata->mr;
+#endif
+	data_len = server->ops->read_data_length(buf, use_rdma_mr);
+	if (!use_rdma_mr && (data_offset + data_len > buflen)) {
+		/* data_len is corrupt -- discard frame */
+		rdata->result = -EIO;
+		return cifs_readv_discard(server, mid);
+	}
+
+	length = rdata->read_into_pages(server, rdata, data_len);
+	if (length < 0)
+		return length;
+
+	server->total_read += length;
+
+	cifs_dbg(FYI, "total_read=%u buflen=%u remaining=%u\n",
+		 server->total_read, buflen, data_len);
+
+	/* discard anything left over */
+	if (server->total_read < buflen)
+		return cifs_readv_discard(server, mid);
+
+	dequeue_mid(mid, false);
+	mid->resp_buf = server->smallbuf;
+	server->smallbuf = NULL;
+	return length;
+}