Commit e66f33bd authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tcp-active-reset' 

Jason Xing says:

===================
tcp: completely support active reset

This time the patch series finally covers all the cases in the active
reset logic. After this, we can know the related exact reason(s).

v4
Link:
1. revise the changelog to avoid future confusion in patch [5/7] (Eric)
2. revise the changelog of patch [6/7] like above.
3. add reviewed-by tags (Eric)

v3
Link: https://lore.kernel.org/all/20240731120955.23542-1-kerneljasonxing@gmail.com/
1. introduce TCP_DISCONNECT_WITH_DATA reason (Eric)
2. use a better name 'TCP_KEEPALIVE_TIMEOUT' (Eric)
3. add three reviewed-by tags (Eric)

v2
Link: https://lore.kernel.org/all/20240730133513.99986-1-kerneljasonxing@gmail.com/


1. use RFC 9293 in the comment and changelog instead of old RFC 793
2. correct the comment and changelog in patch 5
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 2c14119a ba0ca286

include/net/rstreason.h

+39 −0
Original line number Diff line number Diff line
@@ -17,6 +17,12 @@ 
	FN(TCP_ABORT_ON_DATA)		\

	FN(TCP_TIMEWAIT_SOCKET)		\

	FN(INVALID_SYN)			\

	FN(TCP_ABORT_ON_CLOSE)		\

	FN(TCP_ABORT_ON_LINGER)		\

	FN(TCP_ABORT_ON_MEMORY)		\

	FN(TCP_STATE)			\

	FN(TCP_KEEPALIVE_TIMEOUT)	\

	FN(TCP_DISCONNECT_WITH_DATA)	\

	FN(MPTCP_RST_EUNSPEC)		\

	FN(MPTCP_RST_EMPTCP)		\

	FN(MPTCP_RST_ERESOURCE)		\
@@ -84,6 +90,39 @@ enum sk_rst_reason { 
	 * an error, send a reset"

	 */

	SK_RST_REASON_INVALID_SYN,

	/**

	 * @SK_RST_REASON_TCP_ABORT_ON_CLOSE: abort on close

	 * corresponding to LINUX_MIB_TCPABORTONCLOSE

	 */

	SK_RST_REASON_TCP_ABORT_ON_CLOSE,

	/**

	 * @SK_RST_REASON_TCP_ABORT_ON_LINGER: abort on linger

	 * corresponding to LINUX_MIB_TCPABORTONLINGER

	 */

	SK_RST_REASON_TCP_ABORT_ON_LINGER,

	/**

	 * @SK_RST_REASON_TCP_ABORT_ON_MEMORY: abort on memory

	 * corresponding to LINUX_MIB_TCPABORTONMEMORY

	 */

	SK_RST_REASON_TCP_ABORT_ON_MEMORY,

	/**

	 * @SK_RST_REASON_TCP_STATE: abort on tcp state

	 * Please see RFC 9293 for all possible reset conditions

	 */

	SK_RST_REASON_TCP_STATE,

	/**

	 * @SK_RST_REASON_TCP_KEEPALIVE_TIMEOUT: time to timeout

	 * When we have already run out of all the chances, which means

	 * keepalive timeout, we have to reset the connection

	 */

	SK_RST_REASON_TCP_KEEPALIVE_TIMEOUT,

	/**

	 * @SK_RST_REASON_TCP_DISCONNECT_WITH_DATA: disconnect when write

	 * queue is not empty

	 * It means user has written data into the write queue when doing

	 * disconnecting, so we have to send an RST.

	 */

	SK_RST_REASON_TCP_DISCONNECT_WITH_DATA,



	/* Copy from include/uapi/linux/mptcp.h.

	 * These reset fields will not be changed since they adhere to

net/ipv4/tcp.c

+11 −8
Original line number Diff line number Diff line
@@ -2833,7 +2833,7 @@ void __tcp_close(struct sock *sk, long timeout) 
		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);

		tcp_set_state(sk, TCP_CLOSE);

		tcp_send_active_reset(sk, sk->sk_allocation,

				      SK_RST_REASON_NOT_SPECIFIED);

				      SK_RST_REASON_TCP_ABORT_ON_CLOSE);

	} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {

		/* Check zero linger _after_ checking for unread data. */

		sk->sk_prot->disconnect(sk, 0);
@@ -2908,7 +2908,7 @@ void __tcp_close(struct sock *sk, long timeout) 
		if (READ_ONCE(tp->linger2) < 0) {

			tcp_set_state(sk, TCP_CLOSE);

			tcp_send_active_reset(sk, GFP_ATOMIC,

					      SK_RST_REASON_NOT_SPECIFIED);

					      SK_RST_REASON_TCP_ABORT_ON_LINGER);

			__NET_INC_STATS(sock_net(sk),

					LINUX_MIB_TCPABORTONLINGER);

		} else {
@@ -2927,7 +2927,7 @@ void __tcp_close(struct sock *sk, long timeout) 
		if (tcp_check_oom(sk, 0)) {

			tcp_set_state(sk, TCP_CLOSE);

			tcp_send_active_reset(sk, GFP_ATOMIC,

					      SK_RST_REASON_NOT_SPECIFIED);

					      SK_RST_REASON_TCP_ABORT_ON_MEMORY);

			__NET_INC_STATS(sock_net(sk),

					LINUX_MIB_TCPABORTONMEMORY);

		} else if (!check_net(sock_net(sk))) {
@@ -3025,13 +3025,16 @@ int tcp_disconnect(struct sock *sk, int flags) 
		inet_csk_listen_stop(sk);

	} else if (unlikely(tp->repair)) {

		WRITE_ONCE(sk->sk_err, ECONNABORTED);

	} else if (tcp_need_reset(old_state) ||

		   (tp->snd_nxt != tp->write_seq &&

		    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {

	} else if (tcp_need_reset(old_state)) {

		tcp_send_active_reset(sk, gfp_any(), SK_RST_REASON_TCP_STATE);

		WRITE_ONCE(sk->sk_err, ECONNRESET);

	} else if (tp->snd_nxt != tp->write_seq &&

		   (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK)) {

		/* The last check adjusts for discrepancy of Linux wrt. RFC

		 * states

		 */

		tcp_send_active_reset(sk, gfp_any(), SK_RST_REASON_NOT_SPECIFIED);

		tcp_send_active_reset(sk, gfp_any(),

				      SK_RST_REASON_TCP_DISCONNECT_WITH_DATA);

		WRITE_ONCE(sk->sk_err, ECONNRESET);

	} else if (old_state == TCP_SYN_SENT)

		WRITE_ONCE(sk->sk_err, ECONNRESET);
@@ -4649,7 +4652,7 @@ int tcp_abort(struct sock *sk, int err) 
	if (!sock_flag(sk, SOCK_DEAD)) {

		if (tcp_need_reset(sk->sk_state))

			tcp_send_active_reset(sk, GFP_ATOMIC,

					      SK_RST_REASON_NOT_SPECIFIED);

					      SK_RST_REASON_TCP_STATE);

		tcp_done_with_error(sk, err);

	}

net/ipv4/tcp_output.c

+1 −1
Original line number Diff line number Diff line
@@ -3649,7 +3649,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority, 
	/* skb of trace_tcp_send_reset() keeps the skb that caused RST,

	 * skb here is different to the troublesome skb, so use NULL

	 */

	trace_tcp_send_reset(sk, NULL, SK_RST_REASON_NOT_SPECIFIED);

	trace_tcp_send_reset(sk, NULL, reason);

}



/* Send a crossed SYN-ACK during socket establishment.

net/ipv4/tcp_timer.c

+3 −3
Original line number Diff line number Diff line
@@ -125,7 +125,7 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset) 
			do_reset = true;

		if (do_reset)

			tcp_send_active_reset(sk, GFP_ATOMIC,

					      SK_RST_REASON_NOT_SPECIFIED);

					      SK_RST_REASON_TCP_ABORT_ON_MEMORY);

		tcp_done(sk);

		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);

		return 1;
@@ -779,7 +779,7 @@ static void tcp_keepalive_timer (struct timer_list *t) 
				goto out;

			}

		}

		tcp_send_active_reset(sk, GFP_ATOMIC, SK_RST_REASON_NOT_SPECIFIED);

		tcp_send_active_reset(sk, GFP_ATOMIC, SK_RST_REASON_TCP_STATE);

		goto death;

	}
@@ -807,7 +807,7 @@ static void tcp_keepalive_timer (struct timer_list *t) 
		    (user_timeout == 0 &&

		    icsk->icsk_probes_out >= keepalive_probes(tp))) {

			tcp_send_active_reset(sk, GFP_ATOMIC,

					      SK_RST_REASON_NOT_SPECIFIED);

					      SK_RST_REASON_TCP_KEEPALIVE_TIMEOUT);

			tcp_write_err(sk);

			goto out;

		}