cifs_get_root shouldn't use path with tree name

spuiuk · smfrench · commit 374402a2a1df · 2016-12-15T01:42:54.000-06:00
When a server returns the optional flag SMB_SHARE_IS_IN_DFS in response to a tree connect, cifs_build_path_to_root() will return a pathname which includes the hostname. This causes problems with cifs_get_root() which separates each component and does a lookup for each component of the path which in this case will incorrectly include looking up the hostname component as a path component. We encountered a problem with dfs shares hosted by a Netapp. When connecting to nodes pointed to by the DFS share. The tree connect for these nodes return SMB_SHARE_IS_IN_DFS resulting failures in lookup in cifs_get_root(). RH bz: 1373153 The patch was tested against a Netapp simulator and by a user using an actual Netapp server. Signed-off-by: Sachin Prabhu <sprabhu@redhat.com> Reported-by: Pierguido Lambri <plambri@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
@@ -615,7 +615,7 @@ cifs_get_root(struct smb_vol *vol, struct super_block *sb)
 		return dget(sb->s_root);
 
 	full_path = cifs_build_path_to_root(vol, cifs_sb,
-					    cifs_sb_master_tcon(cifs_sb));
+				cifs_sb_master_tcon(cifs_sb), 0);
 	if (full_path == NULL)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
@@ -63,7 +63,8 @@ extern void exit_cifs_spnego(void);
 extern char *build_path_from_dentry(struct dentry *);
 extern char *cifs_build_path_to_root(struct smb_vol *vol,
 				     struct cifs_sb_info *cifs_sb,
-				     struct cifs_tcon *tcon);
+				     struct cifs_tcon *tcon,
+				     int add_treename);
 extern char *build_wildcard_path_from_dentry(struct dentry *direntry);
 extern char *cifs_compose_mount_options(const char *sb_mountdata,
 		const char *fullpath, const struct dfs_info3_param *ref,
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
@@ -3765,7 +3765,8 @@ cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *volume_info)
 		/*
 		 * cifs_build_path_to_root works only when we have a valid tcon
 		 */
-		full_path = cifs_build_path_to_root(volume_info, cifs_sb, tcon);
+		full_path = cifs_build_path_to_root(volume_info, cifs_sb, tcon,
+					tcon->Flags & SMB_SHARE_IS_IN_DFS);
 		if (full_path == NULL) {
 			rc = -ENOMEM;
 			goto mount_fail_check;
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
@@ -47,7 +47,7 @@ renew_parental_timestamps(struct dentry *direntry)
 
 char *
 cifs_build_path_to_root(struct smb_vol *vol, struct cifs_sb_info *cifs_sb,
-			struct cifs_tcon *tcon)
+			struct cifs_tcon *tcon, int add_treename)
 {
 	int pplen = vol->prepath ? strlen(vol->prepath) + 1 : 0;
 	int dfsplen;
@@ -59,7 +59,7 @@ cifs_build_path_to_root(struct smb_vol *vol, struct cifs_sb_info *cifs_sb,
 		return full_path;
 	}
 
-	if (tcon->Flags & SMB_SHARE_IS_IN_DFS)
+	if (add_treename)
 		dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
 	else
 		dfsplen = 0;
