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authorJ. Bruce Fields <bfields@citi.umich.edu>2009-10-25 21:18:19 -0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2009-12-15 14:07:23 -0500
commit3b6cee7bc4b2f7858e9202293104acda8826bb68 (patch)
tree52a1775073ef330a307ec6d81bc2da4d419a71b4
parenteb4c86c6a5adec423c9e615d4937fdddd06a16c5 (diff)
nfsd4: don't continue "under" mounts in V4ROOT case
If /A/mount/point/ has filesystem "B" mounted on top of it, and if "A" is exported, but not "B", then the nfs server has always returned to the client a filehandle for the mountpoint, instead of for the root of "B", allowing the client to see the subtree of "A" that would otherwise be hidden by B. Disable this behavior in the case of V4ROOT exports; we implement the path restrictions of V4ROOT exports by treating *every* directory as if it were a mountpoint, and allowing traversal *only* if the new directory is exported. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
-rw-r--r--fs/nfsd/vfs.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 04bdba12d21b..7e2fdd50113f 100644
--- 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;
}