cifs: Fix retrieval of DFS referrals in cifs_mount()
authorPaulo Alcantara (SUSE) <pc@cjr.nz>
Fri, 22 Nov 2019 15:30:56 +0000 (12:30 -0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 21 Dec 2019 10:04:46 +0000 (11:04 +0100)
commit 5bb30a4dd60e2a10a4de9932daff23e503f1dd2b upstream.

Make sure that DFS referrals are sent to newly resolved root targets
as in a multi tier DFS setup.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Link: https://lkml.kernel.org/r/05aa2995-e85e-0ff4-d003-5bb08bd17a22@canonical.com
Cc: stable@vger.kernel.org
Tested-by: Matthew Ruffell <matthew.ruffell@canonical.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/cifs/connect.c

index a7a0267..20c70cb 100644 (file)
@@ -4709,6 +4709,17 @@ static int is_path_remote(struct cifs_sb_info *cifs_sb, struct smb_vol *vol,
 }
 
 #ifdef CONFIG_CIFS_DFS_UPCALL
+static inline void set_root_tcon(struct cifs_sb_info *cifs_sb,
+                                struct cifs_tcon *tcon,
+                                struct cifs_tcon **root)
+{
+       spin_lock(&cifs_tcp_ses_lock);
+       tcon->tc_count++;
+       tcon->remap = cifs_remap(cifs_sb);
+       spin_unlock(&cifs_tcp_ses_lock);
+       *root = tcon;
+}
+
 int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
 {
        int rc = 0;
@@ -4810,18 +4821,10 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
        /* Cache out resolved root server */
        (void)dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
                             root_path + 1, NULL, NULL);
-       /*
-        * Save root tcon for additional DFS requests to update or create a new
-        * DFS cache entry, or even perform DFS failover.
-        */
-       spin_lock(&cifs_tcp_ses_lock);
-       tcon->tc_count++;
-       tcon->dfs_path = root_path;
+       kfree(root_path);
        root_path = NULL;
-       tcon->remap = cifs_remap(cifs_sb);
-       spin_unlock(&cifs_tcp_ses_lock);
 
-       root_tcon = tcon;
+       set_root_tcon(cifs_sb, tcon, &root_tcon);
 
        for (count = 1; ;) {
                if (!rc && tcon) {
@@ -4858,6 +4861,15 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *vol)
                        mount_put_conns(cifs_sb, xid, server, ses, tcon);
                        rc = mount_get_conns(vol, cifs_sb, &xid, &server, &ses,
                                             &tcon);
+                       /*
+                        * Ensure that DFS referrals go through new root server.
+                        */
+                       if (!rc && tcon &&
+                           (tcon->share_flags & (SHI1005_FLAGS_DFS |
+                                                 SHI1005_FLAGS_DFS_ROOT))) {
+                               cifs_put_tcon(root_tcon);
+                               set_root_tcon(cifs_sb, tcon, &root_tcon);
+                       }
                }
                if (rc) {
                        if (rc == -EACCES || rc == -EOPNOTSUPP)