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Commit 834adff8 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Greg Kroah-Hartman
Browse files

cifs: Always resolve hostname before reconnecting 



commit 28eb24ff75c5ac130eb326b3b4d0dcecfc0f427d upstream.

In case a hostname resolves to a different IP address (e.g. long
running mounts), make sure to resolve it every time prior to calling
generic_ip_connect() in reconnect.

Suggested-by: default avatarSteve French <stfrench@microsoft.com>
Signed-off-by: default avatarPaulo Alcantara <palcantara@suse.de>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
Signed-off-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fafc8e09

fs/cifs/connect.c

+53 −0
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ 
#include "cifs_unicode.h"

#include "cifs_debug.h"

#include "cifs_fs_sb.h"

#include "dns_resolve.h"

#include "ntlmssp.h"

#include "nterr.h"

#include "rfc1002pdu.h"
@@ -313,6 +314,53 @@ static void cifs_prune_tlinks(struct work_struct *work); 
static int cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,

					const char *devname);



/*

 * Resolve hostname and set ip addr in tcp ses. Useful for hostnames that may

 * get their ip addresses changed at some point.

 *

 * This should be called with server->srv_mutex held.

 */

#ifdef CONFIG_CIFS_DFS_UPCALL

static int reconn_set_ipaddr(struct TCP_Server_Info *server)

{

	int rc;

	int len;

	char *unc, *ipaddr = NULL;



	if (!server->hostname)

		return -EINVAL;



	len = strlen(server->hostname) + 3;



	unc = kmalloc(len, GFP_KERNEL);

	if (!unc) {

		cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);

		return -ENOMEM;

	}

	snprintf(unc, len, "\\\\%s", server->hostname);



	rc = dns_resolve_server_name_to_ip(unc, &ipaddr);

	kfree(unc);



	if (rc < 0) {

		cifs_dbg(FYI, "%s: failed to resolve server part of %s to IP: %d\n",

			 __func__, server->hostname, rc);

		return rc;

	}



	rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,

				  strlen(ipaddr));

	kfree(ipaddr);



	return !rc ? -1 : 0;

}

#else

static inline int reconn_set_ipaddr(struct TCP_Server_Info *server)

{

	return 0;

}

#endif



/*

 * cifs tcp session reconnection

 *
@@ -408,6 +456,11 @@ cifs_reconnect(struct TCP_Server_Info *server) 
		rc = generic_ip_connect(server);

		if (rc) {

			cifs_dbg(FYI, "reconnect error %d\n", rc);

			rc = reconn_set_ipaddr(server);

			if (rc) {

				cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n",

					 __func__, rc);

			}

			mutex_unlock(&server->srv_mutex);

			msleep(3000);

		} else {