From 92d7d3e8670251a13f19c7e2047c24e0a5633c65 Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <pshilov@microsoft.com>
Date: Sat, 8 Jul 2017 14:32:00 -0700
Subject: CIFS: Reconnect expired SMB sessions

commit 511c54a2f69195b28afb9dd119f03787b1625bb4 upstream.

According to the MS-SMB2 spec (3.2.5.1.6) once the client receives
STATUS_NETWORK_SESSION_EXPIRED error code from a server it should
reconnect the current SMB session. Currently the client doesn't do
that. This can result in subsequent client requests failing by
the server. The patch adds an additional logic to the demultiplex
thread to identify expired sessions and reconnect them.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 48ef401..7b496a4 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -365,6 +365,8 @@ struct smb_version_operations {
 	unsigned int (*calc_smb_size)(void *);
 	/* check for STATUS_PENDING and process it in a positive case */
 	bool (*is_status_pending)(char *, struct TCP_Server_Info *, int);
+	/* check for STATUS_NETWORK_SESSION_EXPIRED */
+	bool (*is_session_expired)(char *);
 	/* send oplock break response */
 	int (*oplock_response)(struct cifs_tcon *, struct cifs_fid *,
 			       struct cifsInodeInfo *);
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 1f91c9d..cc420d6 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1457,6 +1457,13 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 		return length;
 	server->total_read += length;
 
+	if (server->ops->is_session_expired &&
+	    server->ops->is_session_expired(buf)) {
+		cifs_reconnect(server);
+		wake_up(&server->response_q);
+		return -1;
+	}
+
 	if (server->ops->is_status_pending &&
 	    server->ops->is_status_pending(buf, server, 0)) {
 		discard_remaining_data(server);
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index f6712b6..580b3a4 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -796,6 +796,13 @@ standard_receive3(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 		cifs_dump_mem("Bad SMB: ", buf,
 			min_t(unsigned int, server->total_read, 48));
 
+	if (server->ops->is_session_expired &&
+	    server->ops->is_session_expired(buf)) {
+		cifs_reconnect(server);
+		wake_up(&server->response_q);
+		return -1;
+	}
+
 	if (server->ops->is_status_pending &&
 	    server->ops->is_status_pending(buf, server, length))
 		return -1;
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index b696824..812e488 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1018,6 +1018,18 @@ smb2_is_status_pending(char *buf, struct TCP_Server_Info *server, int length)
 	return true;
 }
 
+static bool
+smb2_is_session_expired(char *buf)
+{
+	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
+
+	if (hdr->Status != STATUS_NETWORK_SESSION_EXPIRED)
+		return false;
+
+	cifs_dbg(FYI, "Session expired\n");
+	return true;
+}
+
 static int
 smb2_oplock_response(struct cifs_tcon *tcon, struct cifs_fid *fid,
 		     struct cifsInodeInfo *cinode)
@@ -1609,6 +1621,7 @@ struct smb_version_operations smb20_operations = {
 	.close_dir = smb2_close_dir,
 	.calc_smb_size = smb2_calc_size,
 	.is_status_pending = smb2_is_status_pending,
+	.is_session_expired = smb2_is_session_expired,
 	.oplock_response = smb2_oplock_response,
 	.queryfs = smb2_queryfs,
 	.mand_lock = smb2_mand_lock,
@@ -1690,6 +1703,7 @@ struct smb_version_operations smb21_operations = {
 	.close_dir = smb2_close_dir,
 	.calc_smb_size = smb2_calc_size,
 	.is_status_pending = smb2_is_status_pending,
+	.is_session_expired = smb2_is_session_expired,
 	.oplock_response = smb2_oplock_response,
 	.queryfs = smb2_queryfs,
 	.mand_lock = smb2_mand_lock,
@@ -1773,6 +1787,7 @@ struct smb_version_operations smb30_operations = {
 	.close_dir = smb2_close_dir,
 	.calc_smb_size = smb2_calc_size,
 	.is_status_pending = smb2_is_status_pending,
+	.is_session_expired = smb2_is_session_expired,
 	.oplock_response = smb2_oplock_response,
 	.queryfs = smb2_queryfs,
 	.mand_lock = smb2_mand_lock,
@@ -1862,6 +1877,7 @@ struct smb_version_operations smb311_operations = {
 	.close_dir = smb2_close_dir,
 	.calc_smb_size = smb2_calc_size,
 	.is_status_pending = smb2_is_status_pending,
+	.is_session_expired = smb2_is_session_expired,
 	.oplock_response = smb2_oplock_response,
 	.queryfs = smb2_queryfs,
 	.mand_lock = smb2_mand_lock,
-- 
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