netdev - Re: [PATCH net-next] tcp: take care of SYN_RECV sockets in tcp_v4_send_ack() and tcp_v6_send

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 11 Jun 2019 08:26:48 +1000
From:   Jonathan Maxwell <jmaxwell37@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net-next] tcp: take care of SYN_RECV sockets in
 tcp_v4_send_ack() and tcp_v6_send_response()

Thanks for fixing that Eric.

On Tue, Jun 11, 2019 at 7:45 AM Eric Dumazet <edumazet@...gle.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 <edumazet@...gle.com>
> Cc: Jon Maxwell <jmaxwell37@...il.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
>