[PATCH 02/14] cifs: update multiplex loop to handle compounded responses

[Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

Signed-off-by: Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 fs/cifs/cifsglob.h |  2 +-
 fs/cifs/connect.c  | 26 +++++++++++++++++++++-----
 fs/cifs/smb2misc.c |  1 +
 fs/cifs/smb2ops.c  | 22 ++++++++++++++++++++++
 4 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 14db722c4b0d..18a961d32e0c 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -449,7 +449,7 @@ struct smb_version_operations {
 				 struct mid_q_entry **);
 	enum securityEnum (*select_sectype)(struct TCP_Server_Info *,
 			    enum securityEnum);
-
+	int (*next_header)(char *);
 };
 
 struct smb_version_values {
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 18a1cb4f2330..a1f84da91eaa 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -840,6 +840,7 @@ cifs_demultiplex_thread(void *p)
 	int length;
 	struct TCP_Server_Info *server = p;
 	unsigned int pdu_length;
+	unsigned int next_offset;
 	char *buf = NULL;
 	struct task_struct *task_to_wake = NULL;
 	struct mid_q_entry *mid_entry;
@@ -877,17 +878,18 @@ cifs_demultiplex_thread(void *p)
 		 * so we can now interpret the length field.
 		 */
 		pdu_length = get_rfc1002_length(buf);
-		server->total_size = pdu_length;
 
-		cifs_dbg(FYI, "RFC1002 header 0x%x\n", pdu_length);
+		cifs_dbg(FYI, "RFC1002 header 0x%x\n", server->total_size);
 		if (!is_smb_response(server, buf[0]))
 			continue;
+next_pdu:
+		server->total_size = pdu_length;
 
 		/* make sure we have enough to get to the MID */
-		if (pdu_length < HEADER_SIZE(server) - 1 -
+		if (server->total_size < HEADER_SIZE(server) - 1 -
 		    server->vals->header_preamble_size) {
 			cifs_dbg(VFS, "SMB response too short (%u bytes)\n",
-				 pdu_length);
+				 server->total_size);
 			cifs_reconnect(server);
 			wake_up(&server->response_q);
 			continue;
@@ -902,6 +904,12 @@ cifs_demultiplex_thread(void *p)
 			continue;
 		server->total_read += length;
 
+		if (server->ops->next_header) {
+			next_offset = server->ops->next_header(buf);
+			if (next_offset)
+				server->total_size = next_offset;
+		}
+
 		if (server->ops->is_transform_hdr &&
 		    server->ops->receive_transform &&
 		    server->ops->is_transform_hdr(buf))
@@ -946,7 +954,15 @@ cifs_demultiplex_thread(void *p)
 				server->ops->dump_detail(buf);
 			cifs_dump_mids(server);
 #endif /* CIFS_DEBUG2 */
-
+		}
+		if (pdu_length > server->total_size) {
+			if (!allocate_buffers(server))
+				continue;
+			pdu_length -= server->total_size;
+			server->total_read = 0;
+			server->large_buf = false;
+			buf = server->smallbuf;
+			goto next_pdu;
 		}
 	} /* end while !EXITING */
 
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index 3bed50ba0d2f..23ac9dc9acf0 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -209,6 +209,7 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr)
 		 * MacOS server pads after SMB2.1 write response with 3 bytes
 		 * of junk. Other servers match RFC1001 len to actual
 		 * SMB2/SMB3 frame length (header + smb2 response specific data)
+		 * Some windows servers do too when compounding is used.
 		 * Log the server error (once), but allow it and continue
 		 * since the frame is parseable.
 		 */
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 5cfcc8c53a56..1c60b4e64656 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2712,6 +2712,24 @@ smb3_handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 				NULL, 0, 0);
 }
 
+static int
+smb2_next_header(char *buf)
+{
+	struct smb2_sync_hdr *hdr = (struct smb2_sync_hdr *)buf;
+	struct smb2_transform_hdr *t_hdr = (struct smb2_transform_hdr *)buf;
+
+	/* FIXME: compounding.
+	 * How does compounding work with smb3 encryption?
+	 * For now, assume that we will have one transform header for each
+	 * smb2 header (and assume that smb2->NextOffset is 0 for all of them.)
+	 */
+	if (hdr->ProtocolId == SMB2_TRANSFORM_PROTO_NUM)
+		return sizeof(struct smb2_transform_hdr) +
+		  le32_to_cpu(t_hdr->OriginalMessageSize);
+
+	return le32_to_cpu(hdr->NextCommand);
+}
+
 struct smb_version_operations smb20_operations = {
 	.compare_fids = smb2_compare_fids,
 	.setup_request = smb2_setup_request,
@@ -2803,6 +2821,7 @@ struct smb_version_operations smb20_operations = {
 	.get_acl_by_fid = get_smb2_acl_by_fid,
 	.set_acl = set_smb2_acl,
 #endif /* CIFS_ACL */
+	.next_header = smb2_next_header,
 };
 
 struct smb_version_operations smb21_operations = {
@@ -2897,6 +2916,7 @@ struct smb_version_operations smb21_operations = {
 	.get_acl_by_fid = get_smb2_acl_by_fid,
 	.set_acl = set_smb2_acl,
 #endif /* CIFS_ACL */
+	.next_header = smb2_next_header,
 };
 
 struct smb_version_operations smb30_operations = {
@@ -3001,6 +3021,7 @@ struct smb_version_operations smb30_operations = {
 	.get_acl_by_fid = get_smb2_acl_by_fid,
 	.set_acl = set_smb2_acl,
 #endif /* CIFS_ACL */
+	.next_header = smb2_next_header,
 };
 
 #ifdef CONFIG_CIFS_SMB311
@@ -3101,6 +3122,7 @@ struct smb_version_operations smb311_operations = {
 	.query_all_EAs = smb2_query_eas,
 	.set_EA = smb2_set_ea,
 #endif /* CIFS_XATTR */
+	.next_header = smb2_next_header,
 };
 #endif /* CIFS_SMB311 */
 
-- 
2.13.3