Cong Wang wrote: > On Thu, Oct 7, 2021 at 1:00 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > > > On 10/2/21 2:37 AM, Cong Wang wrote: > > > From: Cong Wang <cong.wang@xxxxxxxxxxxxx> > > > > > > Yucong noticed we can't poll() sockets in sockmap even > > > when they are the destination sockets of redirections. > > > This is because we never poll any psock queues in ->poll(), > > > except for TCP. With ->sock_is_readable() now we can > > > overwrite >sock_is_readable(), invoke and implement it for > > > both UDP and AF_UNIX sockets. > > > > > > Reported-by: Yucong Sun <sunyucong@xxxxxxxxx> > > > Cc: John Fastabend <john.fastabend@xxxxxxxxx> > > > Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> > > > Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> > > > Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxxx> > > > Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx> > > > --- > > > net/ipv4/udp.c | 2 ++ > > > net/ipv4/udp_bpf.c | 1 + > > > net/unix/af_unix.c | 4 ++++ > > > net/unix/unix_bpf.c | 2 ++ > > > 4 files changed, 9 insertions(+) > > > > > > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c > > > index 2a7825a5b842..4a7e15a43a68 100644 > > > --- a/net/ipv4/udp.c > > > +++ b/net/ipv4/udp.c > > > @@ -2866,6 +2866,8 @@ __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait) > > > !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1) > > > mask &= ~(EPOLLIN | EPOLLRDNORM); > > > > > > + if (sk_is_readable(sk)) > > > + mask |= EPOLLIN | EPOLLRDNORM; > > > > udp_poll() has this extra logic around first_packet_length() which drops all bad csum'ed > > skbs. How does this stand in relation to sk_msg_is_readable()? Is this a concern as well > > there? Maybe makes sense to elaborate a bit more in the commit message for context / future > > reference. > > We don't validate UDP checksums on sockmap RX path, so > it is okay to leave it as it is, but it is worth a comment like > you suggest. I will add a comment in this code. > > If we really need to validate the checksum, it should be addressed > in a separate patch(set), not in this one. > > Thanks. We should validate the checksum before creating the sk_msg so that any parsers running on top of UDP don't parse a bad checksum payload or pass a bad checksum up to user space. I thought there would be a check in the read_sock side, but I didn't see it.
