[PATCH] knfsd: nfsd: call nfsd_setuser() on fh_compose(), fix nfsd4 permissions problem
In the typical v2/v3 case the only new filehandles used as arguments to
operations are filehandles taken directly off the wire, which don't get
dentries until fh_verify() is called.
But in v4 the filehandles that are arguments to operations were often created
by previous operations (putrootfh, lookup, etc.) using fh_compose, which sets
the dentry in the filehandle without calling nfsd_setuser().
This also means that, for example, if filesystem B is mounted on filesystem A,
and filesystem A is exported without root-squashing, then a client can bypass
the rootsquashing on B using a compound that starts at a filehandle in A,
crosses into B using lookups, and then does stuff in B.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index ca96ede..ecc439d 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -187,13 +187,6 @@
goto out;
}
- /* Set user creds for this exportpoint */
- error = nfsd_setuser(rqstp, exp);
- if (error) {
- error = nfserrno(error);
- goto out;
- }
-
/*
* Look up the dentry using the NFS file handle.
*/
@@ -251,6 +244,14 @@
}
cache_get(&exp->h);
+ /* Set user creds for this exportpoint; necessary even in the "just
+ * checking" case because this may be a filehandle that was created by
+ * fh_compose, and that is about to be used in another nfsv4 compound
+ * operation */
+ error = nfserrno(nfsd_setuser(rqstp, exp));
+ if (error)
+ goto out;
+
error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
if (error)
goto out;