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authorPaulo Alcantara <paulo@paulo.ac>2018-11-20 15:16:36 -0200
committerSteve French <stfrench@microsoft.com>2018-12-28 10:13:11 -0600
commit28eb24ff75c5ac130eb326b3b4d0dcecfc0f427d (patch)
tree0c6b6495cbf7e30c3f7716234acd7f80cc821548
parent08744015492fec5a30ab8e2779601ae2b1a5e431 (diff)
cifs: Always resolve hostname before reconnecting
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>
-rw-r--r--fs/cifs/connect.c84
1 files changed, 52 insertions, 32 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 80ef165d5f33..69b9d5606eba 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -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 {