On Thu, Nov 15, 2018 at 04:43:10PM -0500, Neil Horman wrote:
> On Thu, Nov 15, 2018 at 03:22:21PM -0200, Marcelo Ricardo Leitner wrote:
> > On Thu, Nov 15, 2018 at 07:14:28PM +0800, Xin Long wrote:
> > > As rfc7496#section4.5 says about SCTP_PR_SUPPORTED:
> > >
> > > This socket option allows the enabling or disabling of the
> > > negotiation of PR-SCTP support for future associations. For existing
> > > associations, it allows one to query whether or not PR-SCTP support
> > > was negotiated on a particular association.
> > >
> > > It means only sctp sock's prsctp_enable can be set.
> > >
> > > Note that for the limitation of SCTP_{CURRENT|ALL}_ASSOC, we will
> > > add it when introducing SCTP_{FUTURE|CURRENT|ALL}_ASSOC for linux
> > > sctp in another patchset.
> > >
> > > Fixes: 28aa4c26fce2 ("sctp: add SCTP_PR_SUPPORTED on sctp sockopt")
> > > Reported-by: Ying Xu <yinxu@xxxxxxxxxx>
> > > Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
> > > ---
> > > net/sctp/socket.c | 13 +++----------
> > > 1 file changed, 3 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> > > index 739f3e5..e9b8232 100644
> > > --- a/net/sctp/socket.c
> > > +++ b/net/sctp/socket.c
> > > @@ -3940,7 +3940,6 @@ static int sctp_setsockopt_pr_supported(struct sock *sk,
> > > unsigned int optlen)
> > > {
> > > struct sctp_assoc_value params;
> > > - struct sctp_association *asoc;
> > > int retval = -EINVAL;
> > >
> > > if (optlen != sizeof(params))
> > > @@ -3951,16 +3950,10 @@ static int sctp_setsockopt_pr_supported(struct sock *sk,
> > > goto out;
> > > }
> > >
> > > - asoc = sctp_id2assoc(sk, params.assoc_id);
> > > - if (asoc) {
> > > - asoc->prsctp_enable = !!params.assoc_value;
> > > - } else if (!params.assoc_id) {
> > > - struct sctp_sock *sp = sctp_sk(sk);
> > > -
> > > - sp->ep->prsctp_enable = !!params.assoc_value;
> > > - } else {
> > > + if (sctp_style(sk, UDP) && sctp_id2assoc(sk, params.assoc_id))
> >
> > This would allow using a non-existent assoc id on UDP-style sockets to
> > set it at the socket, which is not expected. It should be more like:
> >
> > + if (sctp_style(sk, UDP) && params.assoc_id)
> How do you see that to be the case? sctp_id2assoc will return NULL if an
> association isn't found, so the use of sctp_id2assoc should work just fine.
Right, it will return NULL, and because of that it won't bail out as
it should and will adjust the socket config instead.
> Just checking params.assoc_id would instead fail the setting of any association
> id that isn't 0, which I don't think is what we want at all.
I think it is.
For exisitng associations, we can't set this anymore because it was
already negotiated on the handshake
(sctp_process_ext_param()/SCTP_CID_FWD_TSN) and there is no way back
after it.
For non-existing assocs, they will always inherit it from the socket
value.
Question then is which semantics we want on validating the parameter
here. We have cases such as in sctp_setsockopt_delayed_ack() on which
it will reject using invalid asoc_ids as a way to mean the socket
itself for UDP-style sockets:
asoc = sctp_id2assoc(sk, params.sack_assoc_id);
if (!asoc && params.sack_assoc_id && sctp_style(sk, UDP))
return -EINVAL;
As we are returning the same error for both situations(invalid assoc id
and setting it on existing asoc), we don't need the asoc pointer
itself and can avoid sctp_id2assoc() call, leading to the if() I
suggested.
Marcelo
>
> Neil
>
> >
> > > goto out;
> > > - }
> > > +
> > > + sctp_sk(sk)->ep->prsctp_enable = !!params.assoc_value;
> > >
> > > retval = 0;
> > >
> > > --
> > > 2.1.0
> > >
> >
