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cifs: Always resolve hostname before reconnecting 

commit 28eb24ff75 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: Steve French <stfrench@microsoft.com>
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paulo Alcantara 2018-11-20 15:16:36 -02:00 committed by Greg Kroah-Hartman
parent d2de58eb6e
commit fb713a1737
1 changed files with 53 additions and 0 deletions
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53
fs/cifs/connect.c
View File

@ -48,6 +48,7 @@
#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"
@ -306,6 +307,53 @@ 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
*
@ -403,6 +451,11 @@ 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 {