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Commit aa387d6c authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

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: default avatarJoe Habermann <joe.habermann@gmail.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 030d794b

fs/nfsd/vfs.c

+2 −4
Original line number Original line Diff line number Diff line
@@ -1758,10 +1758,6 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 
	tdentry = tfhp->fh_dentry;

	tdentry = tfhp->fh_dentry;

	tdir = tdentry->d_inode;

	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;

	err = nfserr_perm;

	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))

	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))

		goto out;

		goto out;
@@ -1802,6 +1798,8 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 
	host_err = -EXDEV;

	host_err = -EXDEV;

	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)

	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)

		goto out_dput_new;

		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);

	host_err = nfsd_break_lease(odentry->d_inode);

	if (host_err)

	if (host_err)