Re: [PATCH AUTOSEL for 4.4 065/162] tcp: Add a tcp_filter hook before handle ack packet

[Chenbo Feng]

On Sun, Apr 8, 2018 at 5:28 PM, Sasha Levin
<Alexander.Levin@xxxxxxxxxxxxx> wrote:
> From: Chenbo Feng <fengc@xxxxxxxxxx>
>
> [ Upstream commit 8fac365f63c866a00015fa13932d8ffc584518b8 ]
>
> Currently in both ipv4 and ipv6 code path, the ack packet received when
> sk at TCP_NEW_SYN_RECV state is not filtered by socket filter or cgroup
> filter since it is handled from tcp_child_process and never reaches the
> tcp_filter inside tcp_v4_rcv or tcp_v6_rcv. Adding a tcp_filter hooks
> here can make sure all the ingress tcp packet can be correctly filtered.
>
> Signed-off-by: Chenbo Feng <fengc@xxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
> ---
>  net/ipv4/tcp_ipv4.c | 2 ++
>  net/ipv6/tcp_ipv6.c | 2 ++
>  2 files changed, 4 insertions(+)
>
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 61c93a93f228..2eb9a1747f25 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1639,6 +1639,8 @@ process:
>                 }
>                 if (nsk == sk) {
>                         reqsk_put(req);
> +               } else if (tcp_filter(sk, skb)) {
> +                       goto discard_and_relse;
>                 } else if (tcp_child_process(sk, nsk, skb)) {
>                         tcp_v4_send_reset(nsk, skb);
>                         goto discard_and_relse;
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index 74cbcc4b399c..7d7f0999a919 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -1428,6 +1428,8 @@ process:
>                 if (nsk == sk) {
>                         reqsk_put(req);
>                         tcp_v6_restore_cb(skb);
> +               } else if (tcp_filter(sk, skb)) {
> +                       goto discard_and_relse;
>                 } else if (tcp_child_process(sk, nsk, skb)) {
>                         tcp_v6_send_reset(nsk, skb);
>                         goto discard_and_relse;
> --
> 2.15.1
There is a bug fix for this patch upstream:
"d624d276d1ddacbcb12ad96832ce0c7b82cd25db tcp: fix possible deadlock
in TCP stack vs BPF filter", Please make you include that as well if
you want to add this patch to stable.