On Mon, Jun 10, 2019 at 3:27 PM Jonathan Maxwell <jmaxwel...@gmail.com> wrote:
>
> Thanks for fixing that Eric.
Hi Jonathan.
There is no bug actually, at least not on sk->sk_mark part.
I will send a simpler patch so that sock_net_uid() correctly fetches
sk->sk_uid for FASTOPEN socket.
Thanks !
>
> On Tue, Jun 11, 2019 at 7:45 AM Eric Dumazet <eduma...@google.com> wrote:
> >
> > TCP can send ACK packets on behalf of SYN_RECV sockets.
> >
> > tcp_v4_send_ack() and tcp_v6_send_response() incorrectly
> > dereference sk->sk_mark for non TIME_WAIT sockets.
> >
> > This field is not defined for SYN_RECV sockets.
> >
> > Using sk_to_full_sk() should get back to the listener socket.
> >
> > Note that this also provides a socket pointer to sock_net_uid() calls.
> >
> > Fixes: 00483690552c ("tcp: Add mark for TIMEWAIT sockets")
> > Signed-off-by: Eric Dumazet <eduma...@google.com>
> > Cc: Jon Maxwell <jmaxwel...@gmail.com>
> > ---
> > net/ipv4/tcp_ipv4.c | 6 ++++--
> > net/ipv6/tcp_ipv6.c | 1 +
> > 2 files changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> > index
> > f059fbd81a84314ae6fef37f600b0cf28bd2ad30..2bb27d5eae78efdff52a741904d7526a234595d8
> > 100644
> > --- a/net/ipv4/tcp_ipv4.c
> > +++ b/net/ipv4/tcp_ipv4.c
> > @@ -856,12 +856,14 @@ static void tcp_v4_send_ack(const struct sock *sk,
> > if (oif)
> > arg.bound_dev_if = oif;
> > arg.tos = tos;
> > - arg.uid = sock_net_uid(net, sk_fullsock(sk) ? sk : NULL);
> > local_bh_disable();
> > ctl_sk = this_cpu_read(*net->ipv4.tcp_sk);
> > - if (sk)
> > + if (sk) {
> > + sk = sk_to_full_sk(sk);
> > ctl_sk->sk_mark = (sk->sk_state == TCP_TIME_WAIT) ?
> > inet_twsk(sk)->tw_mark : sk->sk_mark;
> > + }
> > + arg.uid = sock_net_uid(net, sk_fullsock(sk) ? sk : NULL);
> > ip_send_unicast_reply(ctl_sk,
> > skb, &TCP_SKB_CB(skb)->header.h4.opt,
> > ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
> > diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> > index
> > ad7039137a20f9ad8581d9ca01347c67aa8a8433..ea4dd988bc7f9a90e0d95283e10db5a517a59027
> > 100644
> > --- a/net/ipv6/tcp_ipv6.c
> > +++ b/net/ipv6/tcp_ipv6.c
> > @@ -884,6 +884,7 @@ static void tcp_v6_send_response(const struct sock *sk,
> > struct sk_buff *skb, u32
> > }
> >
> > if (sk) {
> > + sk = sk_to_full_sk(sk);
> > if (sk->sk_state == TCP_TIME_WAIT) {
> > mark = inet_twsk(sk)->tw_mark;
> > /* autoflowlabel relies on buff->hash */
> > --
> > 2.22.0.rc2.383.gf4fbbf30c2-goog
> >
