Cong Wang wrote:
> On Mon, Oct 11, 2021 at 10:06 PM John Fastabend
> <john.fastabend@xxxxxxxxx> wrote:
> >
> > Cong Wang wrote:
> > > From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> > >
> > > It turns out the skb's in sock receive queue could have
> > > bad checksums, as both ->poll() and ->recvmsg() validate
> > > checksums. We have to do the same for ->read_sock() path
> > > too before they are redirected in sockmap.
> > >
> > > Fixes: d7f571188ecf ("udp: Implement ->read_sock() for sockmap")
> > > Reported-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> > > Reported-by: John Fastabend <john.fastabend@xxxxxxxxx>
> > > Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
> > > Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> > > Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
> > > ---
> > > net/ipv4/udp.c | 11 +++++++++++
> > > 1 file changed, 11 insertions(+)
> > >
> > > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> > > index 8536b2a7210b..0ae8ab5e05b4 100644
> > > --- a/net/ipv4/udp.c
> > > +++ b/net/ipv4/udp.c
> > > @@ -1808,6 +1808,17 @@ int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
> > > skb = skb_recv_udp(sk, 0, 1, &err);
> > > if (!skb)
> > > return err;
> > > +
> > > + if (udp_lib_checksum_complete(skb)) {
> > > + __UDP_INC_STATS(sock_net(sk), UDP_MIB_CSUMERRORS,
> > > + IS_UDPLITE(sk));
> > > + __UDP_INC_STATS(sock_net(sk), UDP_MIB_INERRORS,
> > > + IS_UDPLITE(sk));
> > > + atomic_inc(&sk->sk_drops);
> > > + kfree_skb(skb);
> >
> > We could use sock_drop() here? Otherwise looks good thanks.
>
> sock_drop() is in include/linux/skmsg.h, I think we need to move it
> to sock.h before using it here in net/ipv4/udp.c, right?
Yes it would be necessary. Lets not do it here otherwise backports
will be ugly.
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
>
> And there are other similar patterns which can be replaced with
> sock_drop(), so we can do the replacement for all in a separate
> patch.
>
> Thanks.
