cifs: Use correct packet length in SMB2_TRANSFORM header

In smb3_init_transform_rq(), 'orig_len' was only counting the request
length, but forgot to count any data pages in the request.

Writing or creating files with the 'seal' mount option was broken.

In addition, do some code refactoring by exporting smb2_rqst_len() to
calculate the appropriate packet size and avoid duplicating the same
calculation all over the code.

The start of the io vector is either the rfc1002 length (4 bytes) or a
SMB2 header which is always > 4. Use this fact to check and skip the
rfc1002 length if requested.

Signed-off-by: Paulo Alcantara <[e-mail]>
Reviewed-by: Aurelien Aptel <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/smb2ops.c

···
 	struct page **pages;
 	struct smb2_transform_hdr *tr_hdr;
 	unsigned int npages = old_rq->rq_npages;
-	unsigned int orig_len = 0;
+	unsigned int orig_len;
 	int i;
 	int rc = -ENOMEM;
 
···
 	new_rq->rq_npages = old_rq->rq_npages;
 	new_rq->rq_pagesz = old_rq->rq_pagesz;
 	new_rq->rq_tailsz = old_rq->rq_tailsz;
-
-	for (i = 0; i < old_rq->rq_nvec; i++)
-		orig_len += old_rq->rq_iov[i].iov_len;
 
 	for (i = 0; i < npages; i++) {
 		pages[i] = alloc_page(GFP_KERNEL|__GFP_HIGHMEM);
···
 	tr_hdr = kmalloc(sizeof(struct smb2_transform_hdr), GFP_KERNEL);
 	if (!tr_hdr)
 		goto err_free_iov;
+
+	orig_len = smb2_rqst_len(old_rq, false);
 
 	/* fill the 2nd iov with a transform header */
 	fill_transform_hdr(tr_hdr, orig_len, old_rq);

fs/cifs/smb2proto.h

···
 extern int smb2_push_mandatory_locks(struct cifsFileInfo *cfile);
 extern void smb2_reconnect_server(struct work_struct *work);
 extern int smb3_crypto_aead_allocate(struct TCP_Server_Info *server);
+extern unsigned long
+smb2_rqst_len(struct smb_rqst *rqst, bool skip_rfc1002_marker);
 
 /*
  * SMB2 Worker functions - most of protocol specific implementation details

fs/cifs/smbdirect.c

···
 #include "smbdirect.h"
 #include "cifs_debug.h"
 #include "cifsproto.h"
+#include "smb2proto.h"
 
 static struct smbd_response *get_empty_queue_buffer(
 		struct smbd_connection *info);
···
 	struct kvec vec;
 	int nvecs;
 	int size;
-	unsigned int buflen = 0, remaining_data_length;
+	unsigned int buflen, remaining_data_length;
 	int start, i, j;
 	int max_iov_size =
 		info->max_send_size - sizeof(struct smbd_data_transfer);
···
 		log_write(ERR, "expected the pdu length in 1st iov, but got %zu\n", rqst->rq_iov[0].iov_len);
 		return -EINVAL;
 	}
-	iov = &rqst->rq_iov[1];
-
-	/* total up iov array first */
-	for (i = 0; i < rqst->rq_nvec-1; i++) {
-		buflen += iov[i].iov_len;
-	}
 
 	/*
 	 * Add in the page array if there is one. The caller needs to set
 	 * rq_tailsz to PAGE_SIZE when the buffer has multiple pages and
 	 * ends at page boundary
 	 */
-	if (rqst->rq_npages) {
-		if (rqst->rq_npages == 1)
-			buflen += rqst->rq_tailsz;
-		else
-			buflen += rqst->rq_pagesz * (rqst->rq_npages - 1) -
-					rqst->rq_offset + rqst->rq_tailsz;
-	}
+	buflen = smb2_rqst_len(rqst, true);
 
 	if (buflen + sizeof(struct smbd_data_transfer) >
 		info->max_fragmented_send_size) {
···
 		rc = -EINVAL;
 		goto done;
 	}
+
+	iov = &rqst->rq_iov[1];
 
 	cifs_dbg(FYI, "Sending smb (RDMA): smb_len=%u\n", buflen);
 	for (i = 0; i < rqst->rq_nvec-1; i++)

fs/cifs/transport.c

···
 	return 0;
 }
 
-static unsigned long
-smb2_rqst_len(struct smb_rqst *rqst)
+unsigned long
+smb2_rqst_len(struct smb_rqst *rqst, bool skip_rfc1002_marker)
 {
 	unsigned int i;
-	struct kvec *iov = rqst->rq_iov;
+	struct kvec *iov;
+	int nvec;
 	unsigned long buflen = 0;
 
+	if (skip_rfc1002_marker && rqst->rq_iov[0].iov_len == 4) {
+		iov = &rqst->rq_iov[1];
+		nvec = rqst->rq_nvec - 1;
+	} else {
+		iov = rqst->rq_iov;
+		nvec = rqst->rq_nvec;
+	}
+
 	/* total up iov array first */
-	for (i = 0; i < rqst->rq_nvec; i++)
+	for (i = 0; i < nvec; i++)
 		buflen += iov[i].iov_len;
 
 	/*
···
 				(char *)&val, sizeof(val));
 
 	for (j = 0; j < num_rqst; j++)
-		send_length += smb2_rqst_len(&rqst[j]);
+		send_length += smb2_rqst_len(&rqst[j], true);
 	rfc1002_marker = cpu_to_be32(send_length);
 
 	/* Generate a rfc1002 marker for SMB2+ */