On Tue, Jun 16, 2009 at 04:47:34PM -0400, bfields wrote:
> On Tue, Jun 16, 2009 at 04:19:32AM +0300, Benny Halevy wrote:
> > From: Andy Adamson <andros@xxxxxxxxxx>
> >
> > Replay processing needs to preceed other error processing.
>
> Why?
Note: there's a slight leak of information here, which I don't think is
really important, but still by default would rather avoid: if a replay
is sent by someone other than the sender of the original create_session,
then sending back the cached result means they get to see a
create_session result that otherwise would have required them to sniff
the network (or decrypt a packet sent with the original user's creds, if
krb5p was in effect).
I doubt that's a big deal: I don't see anything that looks
security-critical in the create_session results. But absent any real
reason to do otherwise, I'd rather check the creds before checking for
replay.
(Note: this is more critical in the case of the sessions DRC: e.g. if
the cached result includes read data, then we could end up exposing
filesystem data to someone who wouldn't otherwise be able to see it.)
--b.
>
> --b.
>
> >
> > Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
> > Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> > ---
> > fs/nfsd/nfs4state.c | 12 ++++++------
> > 1 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index bfc808b..5aef525 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -1378,12 +1378,6 @@ nfsd4_create_session(struct svc_rqst *rqstp,
> > }
> > conf->cl_slot.sl_seqid++;
> > } else if (unconf) {
> > - if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
> > - (ip_addr != unconf->cl_addr)) {
> > - status = nfserr_clid_inuse;
> > - goto out_cache;
> > - }
> > -
> > slot = &unconf->cl_slot;
> > status = check_slot_seqid(cr_ses->seqid, slot->sl_seqid, 0);
> > if (status) {
> > @@ -1392,6 +1386,12 @@ nfsd4_create_session(struct svc_rqst *rqstp,
> > goto out;
> > }
> >
> > + if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
> > + (ip_addr != unconf->cl_addr)) {
> > + status = nfserr_clid_inuse;
> > + goto out_cache;
> > + }
> > +
> > slot->sl_seqid++; /* from 0 to 1 */
> > move_to_confirmed(unconf);
> >
> > --
> > 1.6.3
> >
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