nfsd4: don't continue "under" mounts in V4ROOT case

[safe/jmp/linux-2.6] / fs / nfsd / vfs.c

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 04bdba1..7e2fdd5 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -99,8 +99,16 @@ nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
 
        exp2 = rqst_exp_get_by_name(rqstp, &path);
        if (IS_ERR(exp2)) {
-               if (PTR_ERR(exp2) != -ENOENT)
-                       err = PTR_ERR(exp2);
+               err = PTR_ERR(exp2);
+               /*
+                * We normally allow NFS clients to continue
+                * "underneath" a mountpoint that is not exported.
+                * The exception is V4ROOT, where no traversal is ever
+                * allowed without an explicit export of the new
+                * directory.
+                */
+               if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
+                       err = 0;
                path_put(&path);
                goto out;
        }