nfsd: filter lookup results 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..eaf2f0d 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;
        }
@@ -158,6 +166,19 @@ static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, st
        return 0;
 }
 
+/*
+ * For nfsd purposes, we treat V4ROOT exports as though there was an
+ * export at *every* directory.
+ */
+static int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
+{
+       if (d_mountpoint(dentry))
+               return 1;
+       if (!(exp->ex_flags & NFSEXP_V4ROOT))
+               return 0;
+       return dentry->d_inode != NULL;
+}
+
 __be32
 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
                   const char *name, unsigned int len,
@@ -203,7 +224,7 @@ nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
                /*
                 * check if we have crossed a mount point ...
                 */
-               if (d_mountpoint(dentry)) {
+               if (nfsd_mountpoint(dentry, exp)) {
                        if ((host_err = nfsd_cross_mnt(rqstp, &dentry, &exp))) {
                                dput(dentry);
                                goto out_nfserr;