Return-Path: linux-nfs-owner@vger.kernel.org Received: from fieldses.org ([174.143.236.118]:43158 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755346Ab3DXPjJ (ORCPT ); Wed, 24 Apr 2013 11:39:09 -0400 Received: from bfields by fieldses.org with local (Exim 4.76) (envelope-from ) id 1UV1mn-0005Wg-H0 for linux-nfs@vger.kernel.org; Wed, 24 Apr 2013 11:39:09 -0400 Date: Wed, 24 Apr 2013 11:39:09 -0400 To: linux-nfs@vger.kernel.org Subject: [PATCH] nfsd: fix EXDEV checking in rename Message-ID: <20130424153909.GE20275@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii From: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org List-ID: From: "J. Bruce Fields" 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. Signed-off-by: J. Bruce Fields --- fs/nfsd/vfs.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) Committing for 3.10 if nobody sees a problem with this approach. --b. diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 2b2e239..84ce601 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1758,10 +1758,6 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 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 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 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) -- 1.7.9.5