[PATCH 5.11 026/210] cifs: On cifs_reconnect, resolve the hostname again.

Greg Kroah-Hartman
2021-04-12T09:21:52Z

From: Shyam Prasad N <sprasad@microsoft.com>

commit 4e456b30f78c429b183db420e23b26cde7e03a78 upstream.

On cifs_reconnect, make sure that DNS resolution happens again.
It could be the cause of connection to go dead in the first place.

This also contains the fix for a build issue identified by Intel bot.
Reported-by: kernel test robot <lkp@intel.com>

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
CC: <stable@vger.kernel.org> # 5.11+
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/cifs/Kconfig | 3 +--
fs/cifs/Makefile | 5 +++--
fs/cifs/connect.c | 17 ++++++++++++++++-
3 files changed, 20 insertions(+), 5 deletions(-)

--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -18,6 +18,7 @@ config CIFS
select CRYPTO_AES
select CRYPTO_LIB_DES
select KEYS
+ select DNS_RESOLVER
help
This is the client VFS module for the SMB3 family of NAS protocols,
(including support for the most recent, most secure dialect SMB3.1.1)
@@ -112,7 +113,6 @@ config CIFS_WEAK_PW_HASH
config CIFS_UPCALL
bool "Kerberos/SPNEGO advanced session setup"
depends on CIFS
- select DNS_RESOLVER
help
Enables an upcall mechanism for CIFS which accesses userspace helper
utilities to provide SPNEGO packaged (RFC 4178) Kerberos tickets
@@ -179,7 +179,6 @@ config CIFS_DEBUG_DUMP_KEYS
config CIFS_DFS_UPCALL
bool "DFS feature support"
depends on CIFS
- select DNS_RESOLVER
help
Distributed File System (DFS) support is used to access shares
transparently in an enterprise name space, even if the share
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -10,13 +10,14 @@ cifs-y := trace.o cifsfs.o cifssmb.o cif
cifs_unicode.o nterr.o cifsencrypt.o \
readdir.o ioctl.o sess.o export.o smb1ops.o unc.o winucase.o \
smb2ops.o smb2maperror.o smb2transport.o \
- smb2misc.o smb2pdu.o smb2inode.o smb2file.o cifsacl.o fs_context.o
+ smb2misc.o smb2pdu.o smb2inode.o smb2file.o cifsacl.o fs_context.o \
+ dns_resolve.o

cifs-$(CONFIG_CIFS_XATTR) += xattr.o

cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o

-cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o cifs_dfs_ref.o dfs_cache.o
+cifs-$(CONFIG_CIFS_DFS_UPCALL) += cifs_dfs_ref.o dfs_cache.o

cifs-$(CONFIG_CIFS_SWN_UPCALL) += netlink.o cifs_swn.o

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -87,7 +87,6 @@ static void cifs_prune_tlinks(struct wor
*
* This should be called with server->srv_mutex held.
*/
-#ifdef CONFIG_CIFS_DFS_UPCALL
static int reconn_set_ipaddr_from_hostname(struct TCP_Server_Info *server)
{
int rc;
@@ -124,6 +123,7 @@ static int reconn_set_ipaddr_from_hostna
return !rc ? -1 : 0;
}

+#ifdef CONFIG_CIFS_DFS_UPCALL
/* These functions must be called with server->srv_mutex held */
static void reconn_set_next_dfs_target(struct TCP_Server_Info *server,
struct cifs_sb_info *cifs_sb,
@@ -321,14 +321,29 @@ cifs_reconnect(struct TCP_Server_Info *s
#endif

#ifdef CONFIG_CIFS_DFS_UPCALL
+ if (cifs_sb && cifs_sb->origin_fullpath)
/*
* Set up next DFS target server (if any) for reconnect. If DFS
* feature is disabled, then we will retry last server we
* connected to before.
*/
reconn_set_next_dfs_target(server, cifs_sb, &tgt_list, &tgt_it);
+ else {
+#endif
+ /*
+ * Resolve the hostname again to make sure that IP address is up-to-date.
+ */
+ rc = reconn_set_ipaddr_from_hostname(server);
+ if (rc) {
+ cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n",
+ __func__, rc);
+ }
+
+#ifdef CONFIG_CIFS_DFS_UPCALL
+ }
#endif

+
#ifdef CONFIG_CIFS_SWN_UPCALL
}
#endif