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cifs: Always resolve hostname before reconnecting

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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>
This commit is contained in:
Paulo Alcantara 2018-11-20 15:16:36 -02:00 committed by Steve French
parent 0874401549
commit 28eb24ff75
1 changed files with 52 additions and 32 deletions
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84
fs/cifs/connect.c
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@ -325,6 +325,53 @@ static int cifs_setup_volume_info(struct smb_vol *volume_info, char *mount_data,
const char *devname, bool is_smb3);
static char *extract_hostname(const char *unc);
/*
* 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
#ifdef CONFIG_CIFS_DFS_UPCALL
struct super_cb_data {
struct TCP_Server_Info *server;
@ -366,10 +413,6 @@ static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
struct dfs_cache_tgt_iterator **tgt_it)
{
const char *name;
int rc;
char *ipaddr = NULL;
char *unc;
int len;
if (!cifs_sb || !cifs_sb->origin_fullpath || !tgt_list ||
!server->nr_targets)
@ -393,34 +436,6 @@ static void reconn_inval_dfs_target(struct TCP_Server_Info *server,
if (!server->hostname) {
cifs_dbg(FYI, "%s: failed to extract hostname from target: %d\n",
__func__, -ENOMEM);
return;
}
len = strlen(server->hostname) + 3;
unc = kmalloc(len, GFP_KERNEL);
if (!unc) {
cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
return;
}
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 = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
strlen(ipaddr));
kfree(ipaddr);
if (!rc) {
cifs_dbg(FYI, "%s: failed to get ipaddr out of hostname\n",
__func__);
}
}
@ -567,6 +582,11 @@ cifs_reconnect(struct TCP_Server_Info *server)
reconn_inval_dfs_target(server, cifs_sb, &tgt_list,
&tgt_it);
#endif
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 {