Commit 53c33a16 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tcp-drop-reason-additions' 



Eric Dumazet says:

====================
tcp: drop reason additions

Currently, TCP is either missing drop reasons,
or pretending that some useful packets are dropped.

This patch series makes "perf record -a -e skb:kfree_skb"
much more usable.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 7925c2d9 8fbf1957

include/linux/skbuff.h

+13 −0
Original line number Diff line number Diff line
@@ -381,6 +381,19 @@ enum skb_drop_reason { 
					 * the ofo queue, corresponding to

					 * LINUX_MIB_TCPOFOMERGE

					 */

	SKB_DROP_REASON_TCP_RFC7323_PAWS, /* PAWS check, corresponding to

					   * LINUX_MIB_PAWSESTABREJECTED

					   */

	SKB_DROP_REASON_TCP_INVALID_SEQUENCE, /* Not acceptable SEQ field */

	SKB_DROP_REASON_TCP_RESET,	/* Invalid RST packet */

	SKB_DROP_REASON_TCP_INVALID_SYN, /* Incoming packet has unexpected SYN flag */

	SKB_DROP_REASON_TCP_CLOSE,	/* TCP socket in CLOSE state */

	SKB_DROP_REASON_TCP_FASTOPEN,	/* dropped by FASTOPEN request socket */

	SKB_DROP_REASON_TCP_OLD_ACK,	/* TCP ACK is old, but in window */

	SKB_DROP_REASON_TCP_TOO_OLD_ACK, /* TCP ACK is too old */

	SKB_DROP_REASON_TCP_ACK_UNSENT_DATA, /* TCP ACK for data we haven't sent yet */

	SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE, /* pruned from TCP OFO queue */

	SKB_DROP_REASON_TCP_OFO_DROP,	/* data already in receive queue */

	SKB_DROP_REASON_IP_OUTNOROUTES,	/* route lookup failed */

	SKB_DROP_REASON_BPF_CGROUP_EGRESS,	/* dropped by

						 * BPF_PROG_TYPE_CGROUP_SKB

include/trace/events/skb.h

+14 −0
Original line number Diff line number Diff line
@@ -37,6 +37,20 @@ 
	EM(SKB_DROP_REASON_TCP_OLD_DATA, TCP_OLD_DATA)		\

	EM(SKB_DROP_REASON_TCP_OVERWINDOW, TCP_OVERWINDOW)	\

	EM(SKB_DROP_REASON_TCP_OFOMERGE, TCP_OFOMERGE)		\

	EM(SKB_DROP_REASON_TCP_OFO_DROP, TCP_OFO_DROP)		\

	EM(SKB_DROP_REASON_TCP_RFC7323_PAWS, TCP_RFC7323_PAWS)	\

	EM(SKB_DROP_REASON_TCP_INVALID_SEQUENCE,		\

	   TCP_INVALID_SEQUENCE)				\

	EM(SKB_DROP_REASON_TCP_RESET, TCP_RESET)		\

	EM(SKB_DROP_REASON_TCP_INVALID_SYN, TCP_INVALID_SYN)	\

	EM(SKB_DROP_REASON_TCP_CLOSE, TCP_CLOSE)		\

	EM(SKB_DROP_REASON_TCP_FASTOPEN, TCP_FASTOPEN)		\

	EM(SKB_DROP_REASON_TCP_OLD_ACK, TCP_OLD_ACK)		\

	EM(SKB_DROP_REASON_TCP_TOO_OLD_ACK, TCP_TOO_OLD_ACK)	\

	EM(SKB_DROP_REASON_TCP_ACK_UNSENT_DATA,			\

	   TCP_ACK_UNSENT_DATA)					\

	EM(SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE,			\

	  TCP_OFO_QUEUE_PRUNE)					\

	EM(SKB_DROP_REASON_IP_OUTNOROUTES, IP_OUTNOROUTES)	\

	EM(SKB_DROP_REASON_BPF_CGROUP_EGRESS,			\

	   BPF_CGROUP_EGRESS)					\

net/ipv4/tcp_input.c

+73 −54
Original line number Diff line number Diff line
@@ -3766,7 +3766,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) 
		if (before(ack, prior_snd_una - tp->max_window)) {

			if (!(flag & FLAG_NO_CHALLENGE_ACK))

				tcp_send_challenge_ack(sk);

			return -1;

			return -SKB_DROP_REASON_TCP_TOO_OLD_ACK;

		}

		goto old_ack;

	}
@@ -3775,7 +3775,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) 
	 * this segment (RFC793 Section 3.9).

	 */

	if (after(ack, tp->snd_nxt))

		return -1;

		return -SKB_DROP_REASON_TCP_ACK_UNSENT_DATA;



	if (after(ack, prior_snd_una)) {

		flag |= FLAG_SND_UNA_ADVANCED;
@@ -4674,7 +4674,7 @@ static bool tcp_ooo_try_coalesce(struct sock *sk, 
{

	bool res = tcp_try_coalesce(sk, to, from, fragstolen);



	/* In case tcp_drop() is called later, update to->gso_segs */

	/* In case tcp_drop_reason() is called later, update to->gso_segs */

	if (res) {

		u32 gso_segs = max_t(u16, 1, skb_shinfo(to)->gso_segs) +

			       max_t(u16, 1, skb_shinfo(from)->gso_segs);
@@ -4691,11 +4691,6 @@ static void tcp_drop_reason(struct sock *sk, struct sk_buff *skb, 
	kfree_skb_reason(skb, reason);

}



static void tcp_drop(struct sock *sk, struct sk_buff *skb)

{

	tcp_drop_reason(sk, skb, SKB_DROP_REASON_NOT_SPECIFIED);

}



/* This one checks to see if we can put data from the

 * out_of_order queue into the receive_queue.

 */
@@ -4723,7 +4718,7 @@ static void tcp_ofo_queue(struct sock *sk) 
		rb_erase(&skb->rbnode, &tp->out_of_order_queue);



		if (unlikely(!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt))) {

			tcp_drop(sk, skb);

			tcp_drop_reason(sk, skb, SKB_DROP_REASON_TCP_OFO_DROP);

			continue;

		}
@@ -5334,7 +5329,8 @@ static bool tcp_prune_ofo_queue(struct sock *sk) 
		prev = rb_prev(node);

		rb_erase(node, &tp->out_of_order_queue);

		goal -= rb_to_skb(node)->truesize;

		tcp_drop(sk, rb_to_skb(node));

		tcp_drop_reason(sk, rb_to_skb(node),

				SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE);

		if (!prev || goal <= 0) {

			sk_mem_reclaim(sk);

			if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
@@ -5667,7 +5663,7 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
				  const struct tcphdr *th, int syn_inerr)

{

	struct tcp_sock *tp = tcp_sk(sk);

	bool rst_seq_match = false;

	SKB_DR(reason);



	/* RFC1323: H1. Apply PAWS check first. */

	if (tcp_fast_parse_options(sock_net(sk), skb, th, tp) &&
@@ -5679,6 +5675,7 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
						  LINUX_MIB_TCPACKSKIPPEDPAWS,

						  &tp->last_oow_ack_time))

				tcp_send_dupack(sk, skb);

			SKB_DR_SET(reason, TCP_RFC7323_PAWS);

			goto discard;

		}

		/* Reset is accepted even if it did not pass PAWS. */
@@ -5700,8 +5697,9 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
						  &tp->last_oow_ack_time))

				tcp_send_dupack(sk, skb);

		} else if (tcp_reset_check(sk, skb)) {

			tcp_reset(sk, skb);

			goto reset;

		}

		SKB_DR_SET(reason, TCP_INVALID_SEQUENCE);

		goto discard;

	}
@@ -5717,9 +5715,10 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
		 *     Send a challenge ACK

		 */

		if (TCP_SKB_CB(skb)->seq == tp->rcv_nxt ||

		    tcp_reset_check(sk, skb)) {

			rst_seq_match = true;

		} else if (tcp_is_sack(tp) && tp->rx_opt.num_sacks > 0) {

		    tcp_reset_check(sk, skb))

			goto reset;



		if (tcp_is_sack(tp) && tp->rx_opt.num_sacks > 0) {

			struct tcp_sack_block *sp = &tp->selective_acks[0];

			int max_sack = sp[0].end_seq;

			int this_sack;
@@ -5732,12 +5731,9 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
			}



			if (TCP_SKB_CB(skb)->seq == max_sack)

				rst_seq_match = true;

				goto reset;

		}



		if (rst_seq_match)

			tcp_reset(sk, skb);

		else {

		/* Disable TFO if RST is out-of-order

		 * and no data has been received

		 * for current active TFO socket
@@ -5746,7 +5742,7 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
		    sk->sk_state == TCP_ESTABLISHED)

			tcp_fastopen_active_disable(sk);

		tcp_send_challenge_ack(sk);

		}

		SKB_DR_SET(reason, TCP_RESET);

		goto discard;

	}
@@ -5761,6 +5757,7 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
			TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);

		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNCHALLENGE);

		tcp_send_challenge_ack(sk);

		SKB_DR_SET(reason, TCP_INVALID_SYN);

		goto discard;

	}
@@ -5769,7 +5766,12 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, 
	return true;



discard:

	tcp_drop(sk, skb);

	tcp_drop_reason(sk, skb, reason);

	return false;



reset:

	tcp_reset(sk, skb);

	__kfree_skb(skb);

	return false;

}
@@ -5956,7 +5958,8 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb) 
		return;



step5:

	if (tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT) < 0)

	reason = tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT);

	if (reason < 0)

		goto discard;



	tcp_rcv_rtt_measure_ts(sk, skb);
@@ -6136,6 +6139,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
	struct tcp_fastopen_cookie foc = { .len = -1 };

	int saved_clamp = tp->rx_opt.mss_clamp;

	bool fastopen_fail;

	SKB_DR(reason);



	tcp_parse_options(sock_net(sk), skb, &tp->rx_opt, 0, &foc);

	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
@@ -6178,7 +6182,9 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 


		if (th->rst) {

			tcp_reset(sk, skb);

			goto discard;

consume:

			__kfree_skb(skb);

			return 0;

		}



		/* rfc793:
@@ -6188,9 +6194,10 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
		 *    See note below!

		 *                                        --ANK(990513)

		 */

		if (!th->syn)

		if (!th->syn) {

			SKB_DR_SET(reason, TCP_FLAGS);

			goto discard_and_undo;



		}

		/* rfc793:

		 *   "If the SYN bit is on ...

		 *    are acceptable then ...
@@ -6267,13 +6274,9 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
			tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);

			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,

						  TCP_DELACK_MAX, TCP_RTO_MAX);



discard:

			tcp_drop(sk, skb);

			return 0;

		} else {

			tcp_send_ack(sk);

			goto consume;

		}

		tcp_send_ack(sk);

		return -1;

	}
@@ -6285,15 +6288,16 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
		 *

		 *      Otherwise (no ACK) drop the segment and return."

		 */



		SKB_DR_SET(reason, TCP_RESET);

		goto discard_and_undo;

	}



	/* PAWS check. */

	if (tp->rx_opt.ts_recent_stamp && tp->rx_opt.saw_tstamp &&

	    tcp_paws_reject(&tp->rx_opt, 0))

	    tcp_paws_reject(&tp->rx_opt, 0)) {

		SKB_DR_SET(reason, TCP_RFC7323_PAWS);

		goto discard_and_undo;



	}

	if (th->syn) {

		/* We see SYN without ACK. It is attempt of

		 * simultaneous connect with crossed SYNs.
@@ -6342,7 +6346,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
		 */

		return -1;

#else

		goto discard;

		goto consume;

#endif

	}

	/* "fifth, if neither of the SYN or RST bits is set then
@@ -6352,7 +6356,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
discard_and_undo:

	tcp_clear_options(&tp->rx_opt);

	tp->rx_opt.mss_clamp = saved_clamp;

	goto discard;

	tcp_drop_reason(sk, skb, reason);

	return 0;



reset_and_undo:

	tcp_clear_options(&tp->rx_opt);
@@ -6407,21 +6412,26 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
	struct request_sock *req;

	int queued = 0;

	bool acceptable;

	SKB_DR(reason);



	switch (sk->sk_state) {

	case TCP_CLOSE:

		SKB_DR_SET(reason, TCP_CLOSE);

		goto discard;



	case TCP_LISTEN:

		if (th->ack)

			return 1;



		if (th->rst)

		if (th->rst) {

			SKB_DR_SET(reason, TCP_RESET);

			goto discard;



		}

		if (th->syn) {

			if (th->fin)

			if (th->fin) {

				SKB_DR_SET(reason, TCP_FLAGS);

				goto discard;

			}

			/* It is possible that we process SYN packets from backlog,

			 * so we need to make sure to disable BH and RCU right there.

			 */
@@ -6436,6 +6446,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
			consume_skb(skb);

			return 0;

		}

		SKB_DR_SET(reason, TCP_FLAGS);

		goto discard;



	case TCP_SYN_SENT:
@@ -6462,13 +6473,16 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
		WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&

		    sk->sk_state != TCP_FIN_WAIT1);



		if (!tcp_check_req(sk, skb, req, true, &req_stolen))

		if (!tcp_check_req(sk, skb, req, true, &req_stolen)) {

			SKB_DR_SET(reason, TCP_FASTOPEN);

			goto discard;

		}

	}



	if (!th->ack && !th->rst && !th->syn)

	if (!th->ack && !th->rst && !th->syn) {

		SKB_DR_SET(reason, TCP_FLAGS);

		goto discard;



	}

	if (!tcp_validate_incoming(sk, skb, th, 0))

		return 0;
@@ -6481,6 +6495,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
		if (sk->sk_state == TCP_SYN_RECV)

			return 1;	/* send one RST */

		tcp_send_challenge_ack(sk);

		SKB_DR_SET(reason, TCP_OLD_ACK);

		goto discard;

	}

	switch (sk->sk_state) {
@@ -6574,7 +6589,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
			inet_csk_reset_keepalive_timer(sk, tmo);

		} else {

			tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);

			goto discard;

			goto consume;

		}

		break;

	}
@@ -6582,7 +6597,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
	case TCP_CLOSING:

		if (tp->snd_una == tp->write_seq) {

			tcp_time_wait(sk, TCP_TIME_WAIT, 0);

			goto discard;

			goto consume;

		}

		break;
@@ -6590,7 +6605,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
		if (tp->snd_una == tp->write_seq) {

			tcp_update_metrics(sk);

			tcp_done(sk);

			goto discard;

			goto consume;

		}

		break;

	}
@@ -6641,9 +6656,13 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 


	if (!queued) {

discard:

		tcp_drop(sk, skb);

		tcp_drop_reason(sk, skb, reason);

	}

	return 0;



consume:

	__kfree_skb(skb);

	return 0;

}

EXPORT_SYMBOL(tcp_rcv_state_process);