nfsd: fix EXDEV checking in rename
We again check for the EXDEV a little later on, so the first check is
redundant. This check is also slightly racier, since a badly timed
eviction from the export cache could leave us with the two fh_export
pointers pointing to two different cache entries which each refer to the
same underlying export.
It's better to compare vfsmounts as the later check does, but that
leaves a minor security hole in the case where the two exports refer to
two different directories especially if (for example) they have
different root-squashing options.
So, compare ex_path.dentry too.
Reported-by: Joe Habermann <joe.habermann@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 2b2e2396..84ce601 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1758,10 +1758,6 @@
tdentry = tfhp->fh_dentry;
tdir = tdentry->d_inode;
- err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev;
- if (ffhp->fh_export != tfhp->fh_export)
- goto out;
-
err = nfserr_perm;
if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
goto out;
@@ -1802,6 +1798,8 @@
host_err = -EXDEV;
if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
goto out_dput_new;
+ if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
+ goto out_dput_new;
host_err = nfsd_break_lease(odentry->d_inode);
if (host_err)