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Date: Mon, 14 Dec 2015 09:52:02 -0800
From: Tom Herbert <tom@...bertland.com>
To: Lorenzo Colitti <lorenzo@...gle.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>,
Hannes Frederic Sowa <hannes@...essinduktion.org>,
Eric Dumazet <eric.dumazet@...il.com>,
Erik Kline <ek@...gle.com>,
Maciej Żenczykowski <zenczykowski@...il.com>
Subject: Re: [PATCH v5 4/4] net: diag: Support destroying TCP sockets.
On Mon, Dec 14, 2015 at 9:29 AM, Lorenzo Colitti <lorenzo@...gle.com> wrote:
> This implements SOCK_DESTROY for TCP sockets. It causes all
> blocking calls on the socket to fail fast with ECONNABORTED and
> causes a protocol close of the socket. It informs the other end
> of the connection by sending a RST, i.e., initiating a TCP ABORT
> as per RFC 793. ECONNABORTED was chosen for consistency with
> FreeBSD.
>
> Signed-off-by: Lorenzo Colitti <lorenzo@...gle.com>
> ---
> include/net/tcp.h | 4 ++++
> net/ipv4/Kconfig | 13 +++++++++++++
> net/ipv4/tcp.c | 34 ++++++++++++++++++++++++++++++++++
> net/ipv4/tcp_diag.c | 19 +++++++++++++++++++
> net/ipv4/tcp_ipv4.c | 3 +++
> net/ipv6/tcp_ipv6.c | 3 +++
> 6 files changed, 76 insertions(+)
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index f80e74c..505cef5 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -1170,6 +1170,10 @@ void tcp_set_state(struct sock *sk, int state);
>
> void tcp_done(struct sock *sk);
>
> +#if CONFIG_INET_DIAG_DESTROY
> +int tcp_abort(struct sock *sk);
> +#endif
> +
> static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
> {
> rx_opt->dsack = 0;
> diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
> index 416dfa0..31c4496 100644
> --- a/net/ipv4/Kconfig
> +++ b/net/ipv4/Kconfig
> @@ -436,6 +436,19 @@ config INET_UDP_DIAG
> Support for UDP socket monitoring interface used by the ss tool.
> If unsure, say Y.
>
> +config INET_DIAG_DESTROY
> + bool "INET: allow privileged process to administratively close sockets"
> + depends on INET_DIAG && (IPV6 || IPV6=n)
> + default n
> + ---help---
> + Provides a SOCK_DESTROY operation that allows privileged processes
> + (e.g., a connection manager or a network administration tool such as
> + ss) to close sockets opened by other processes. Closing a socket in
> + this way interrupts any blocking read/writes/connect operations on
> + the socket and causes future socket calls to behave as if the socket
> + had been disconnected.
> + If unsure, say N.
> +
> menuconfig TCP_CONG_ADVANCED
> bool "TCP: advanced congestion control"
> ---help---
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index c82cca1..fc5068d 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -3080,6 +3080,40 @@ void tcp_done(struct sock *sk)
> }
> EXPORT_SYMBOL_GPL(tcp_done);
>
> +#ifdef CONFIG_INET_DIAG_DESTROY
This is a general use function it should not be under a CONFIG.
> +int tcp_abort(struct sock *sk)
Please add an err argument for setting sk->err. A value of zero could
mean to use the default value (ECONNABORTED).
> +{
> + if (!sk_fullsock(sk)) {
> + sock_gen_put(sk);
> + return -EOPNOTSUPP;
> + }
> +
> + /* Don't race with userspace socket closes such as tcp_close. */
> + lock_sock(sk);
> +
> + /* Don't race with BH socket closes such as inet_csk_listen_stop. */
> + local_bh_disable();
> + bh_lock_sock(sk);
> +
> + if (!sock_flag(sk, SOCK_DEAD)) {
> + sk->sk_err = ECONNABORTED;
> + /* This barrier is coupled with smp_rmb() in tcp_poll() */
> + smp_wmb();
> + sk->sk_error_report(sk);
> + if (tcp_need_reset(sk->sk_state))
> + tcp_send_active_reset(sk, GFP_ATOMIC);
> + tcp_done(sk);
> + }
> +
> + bh_unlock_sock(sk);
> + local_bh_enable();
> + release_sock(sk);
> + sock_put(sk);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(tcp_abort);
> +#endif
> +
> extern struct tcp_congestion_ops tcp_reno;
>
> static __initdata unsigned long thash_entries;
> diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
> index b316040..8d435f17 100644
> --- a/net/ipv4/tcp_diag.c
> +++ b/net/ipv4/tcp_diag.c
> @@ -10,6 +10,8 @@
> */
>
> #include <linux/module.h>
> +#include <linux/net.h>
> +#include <linux/sock_diag.h>
> #include <linux/inet_diag.h>
>
> #include <linux/tcp.h>
> @@ -46,12 +48,29 @@ static int tcp_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
> return inet_diag_dump_one_icsk(&tcp_hashinfo, in_skb, nlh, req);
> }
>
> +#ifdef CONFIG_INET_DIAG_DESTROY
> +static int tcp_diag_destroy(struct sk_buff *in_skb,
> + const struct inet_diag_req_v2 *req)
> +{
> + struct net *net = sock_net(in_skb->sk);
> + struct sock *sk = inet_diag_find_one_icsk(net, &tcp_hashinfo, req);
> +
> + if (IS_ERR(sk))
> + return PTR_ERR(sk);
> +
> + return sock_diag_destroy(sk);
> +}
> +#endif
> +
> static const struct inet_diag_handler tcp_diag_handler = {
> .dump = tcp_diag_dump,
> .dump_one = tcp_diag_dump_one,
> .idiag_get_info = tcp_diag_get_info,
> .idiag_type = IPPROTO_TCP,
> .idiag_info_size = sizeof(struct tcp_info),
> +#ifdef CONFIG_INET_DIAG_DESTROY
> + .destroy = tcp_diag_destroy,
> +#endif
> };
>
> static int __init tcp_diag_init(void)
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index db00343..5e28bf1 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -2342,6 +2342,9 @@ struct proto tcp_prot = {
> .destroy_cgroup = tcp_destroy_cgroup,
> .proto_cgroup = tcp_proto_cgroup,
> #endif
> +#ifdef CONFIG_INET_DIAG_DESTROY
> + .diag_destroy = tcp_abort,
> +#endif
> };
> EXPORT_SYMBOL(tcp_prot);
>
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index c16e3fb..289c5db 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -1890,6 +1890,9 @@ struct proto tcpv6_prot = {
> .proto_cgroup = tcp_proto_cgroup,
> #endif
> .clear_sk = tcp_v6_clear_sk,
> +#ifdef CONFIG_INET_DIAG_DESTROY
> + .diag_destroy = tcp_abort,
> +#endif
> };
>
> static const struct inet6_protocol tcpv6_protocol = {
> --
> 2.6.0.rc2.230.g3dd15c0
>
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