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Patch "CIFS: Reconnect expired SMB sessions" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Oct 12, 2017 Stable branch

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This is a note to let you know that I've just added the patch titled

CIFS: Reconnect expired SMB sessions

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cifs-reconnect-expired-smb-sessions.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 511c54a2f69195b28afb9dd119f03787b1625bb4 Mon Sep 17 00:00:00 2001

From: Pavel Shilovsky <[email protected]>
Date: Sat, 8 Jul 2017 14:32:00 -0700
Subject: CIFS: Reconnect expired SMB sessions

From: Pavel Shilovsky <[email protected]>

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 <[email protected]>
Signed-off-by Steve French <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 fs/cifs/cifsglob.h |    2 ++
 fs/cifs/cifssmb.c  |    7 +++++++
 fs/cifs/connect.c  |    7 +++++++
 fs/cifs/smb2ops.c  |   16 ++++++++++++++++
 4 files changed, 32 insertions(+)
fs/cifs/cifsglob.h +2 -0
@@ -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 *);
fs/cifs/cifssmb.c +7 -0
@@ -1457,6 +1457,13 @@ cifs_readv_receive(struct TCP_Server_Inf
 		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);
fs/cifs/connect.c +7 -0
@@ -796,6 +796,13 @@ standard_receive3(struct TCP_Server_Info
 		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;
fs/cifs/smb2ops.c +16 -0
@@ -1018,6 +1018,18 @@ smb2_is_status_pending(char *buf, struct
 	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_oper
 	.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_oper
 	.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_oper
 	.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_ope
 	.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,

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/cifs-reconnect-expired-smb-sessions.patch