Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1475 insertions, 0 deletions

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
new file mode 100644
index 000000000..e9178115a
--- /dev/null
+++ b/net/rxrpc/input.c
@@ -0,0 +1,1475 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* RxRPC packet reception
+ *
+ * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <linux/errqueue.h>
+#include <linux/udp.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/icmp.h>
+#include <linux/gfp.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include <net/ip.h>
+#include <net/udp.h>
+#include <net/net_namespace.h>
+#include "ar-internal.h"
+
+static void rxrpc_proto_abort(const char *why,
+			      struct rxrpc_call *call, rxrpc_seq_t seq)
+{
+	if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, -EBADMSG)) {
+		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
+		rxrpc_queue_call(call);
+	}
+}
+
+/*
+ * Do TCP-style congestion management [RFC 5681].
+ */
+static void rxrpc_congestion_management(struct rxrpc_call *call,
+					struct sk_buff *skb,
+					struct rxrpc_ack_summary *summary,
+					rxrpc_serial_t acked_serial)
+{
+	enum rxrpc_congest_change change = rxrpc_cong_no_change;
+	unsigned int cumulative_acks = call->cong_cumul_acks;
+	unsigned int cwnd = call->cong_cwnd;
+	bool resend = false;
+
+	summary->flight_size =
+		(call->tx_top - call->tx_hard_ack) - summary->nr_acks;
+
+	if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
+		summary->retrans_timeo = true;
+		call->cong_ssthresh = max_t(unsigned int,
+					    summary->flight_size / 2, 2);
+		cwnd = 1;
+		if (cwnd >= call->cong_ssthresh &&
+		    call->cong_mode == RXRPC_CALL_SLOW_START) {
+			call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+			call->cong_tstamp = skb->tstamp;
+			cumulative_acks = 0;
+		}
+	}
+
+	cumulative_acks += summary->nr_new_acks;
+	cumulative_acks += summary->nr_rot_new_acks;
+	if (cumulative_acks > 255)
+		cumulative_acks = 255;
+
+	summary->mode = call->cong_mode;
+	summary->cwnd = call->cong_cwnd;
+	summary->ssthresh = call->cong_ssthresh;
+	summary->cumulative_acks = cumulative_acks;
+	summary->dup_acks = call->cong_dup_acks;
+
+	switch (call->cong_mode) {
+	case RXRPC_CALL_SLOW_START:
+		if (summary->nr_nacks > 0)
+			goto packet_loss_detected;
+		if (summary->cumulative_acks > 0)
+			cwnd += 1;
+		if (cwnd >= call->cong_ssthresh) {
+			call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+			call->cong_tstamp = skb->tstamp;
+		}
+		goto out;
+
+	case RXRPC_CALL_CONGEST_AVOIDANCE:
+		if (summary->nr_nacks > 0)
+			goto packet_loss_detected;
+
+		/* We analyse the number of packets that get ACK'd per RTT
+		 * period and increase the window if we managed to fill it.
+		 */
+		if (call->peer->rtt_count == 0)
+			goto out;
+		if (ktime_before(skb->tstamp,
+				 ktime_add_us(call->cong_tstamp,
+					      call->peer->srtt_us >> 3)))
+			goto out_no_clear_ca;
+		change = rxrpc_cong_rtt_window_end;
+		call->cong_tstamp = skb->tstamp;
+		if (cumulative_acks >= cwnd)
+			cwnd++;
+		goto out;
+
+	case RXRPC_CALL_PACKET_LOSS:
+		if (summary->nr_nacks == 0)
+			goto resume_normality;
+
+		if (summary->new_low_nack) {
+			change = rxrpc_cong_new_low_nack;
+			call->cong_dup_acks = 1;
+			if (call->cong_extra > 1)
+				call->cong_extra = 1;
+			goto send_extra_data;
+		}
+
+		call->cong_dup_acks++;
+		if (call->cong_dup_acks < 3)
+			goto send_extra_data;
+
+		change = rxrpc_cong_begin_retransmission;
+		call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
+		call->cong_ssthresh = max_t(unsigned int,
+					    summary->flight_size / 2, 2);
+		cwnd = call->cong_ssthresh + 3;
+		call->cong_extra = 0;
+		call->cong_dup_acks = 0;
+		resend = true;
+		goto out;
+
+	case RXRPC_CALL_FAST_RETRANSMIT:
+		if (!summary->new_low_nack) {
+			if (summary->nr_new_acks == 0)
+				cwnd += 1;
+			call->cong_dup_acks++;
+			if (call->cong_dup_acks == 2) {
+				change = rxrpc_cong_retransmit_again;
+				call->cong_dup_acks = 0;
+				resend = true;
+			}
+		} else {
+			change = rxrpc_cong_progress;
+			cwnd = call->cong_ssthresh;
+			if (summary->nr_nacks == 0)
+				goto resume_normality;
+		}
+		goto out;
+
+	default:
+		BUG();
+		goto out;
+	}
+
+resume_normality:
+	change = rxrpc_cong_cleared_nacks;
+	call->cong_dup_acks = 0;
+	call->cong_extra = 0;
+	call->cong_tstamp = skb->tstamp;
+	if (cwnd < call->cong_ssthresh)
+		call->cong_mode = RXRPC_CALL_SLOW_START;
+	else
+		call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
+out:
+	cumulative_acks = 0;
+out_no_clear_ca:
+	if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
+		cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
+	call->cong_cwnd = cwnd;
+	call->cong_cumul_acks = cumulative_acks;
+	trace_rxrpc_congest(call, summary, acked_serial, change);
+	if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
+		rxrpc_queue_call(call);
+	return;
+
+packet_loss_detected:
+	change = rxrpc_cong_saw_nack;
+	call->cong_mode = RXRPC_CALL_PACKET_LOSS;
+	call->cong_dup_acks = 0;
+	goto send_extra_data;
+
+send_extra_data:
+	/* Send some previously unsent DATA if we have some to advance the ACK
+	 * state.
+	 */
+	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
+	    RXRPC_TX_ANNO_LAST ||
+	    summary->nr_acks != call->tx_top - call->tx_hard_ack) {
+		call->cong_extra++;
+		wake_up(&call->waitq);
+	}
+	goto out_no_clear_ca;
+}
+
+/*
+ * Apply a hard ACK by advancing the Tx window.
+ */
+static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
+				   struct rxrpc_ack_summary *summary)
+{
+	struct sk_buff *skb, *list = NULL;
+	bool rot_last = false;
+	int ix;
+	u8 annotation;
+
+	if (call->acks_lowest_nak == call->tx_hard_ack) {
+		call->acks_lowest_nak = to;
+	} else if (before_eq(call->acks_lowest_nak, to)) {
+		summary->new_low_nack = true;
+		call->acks_lowest_nak = to;
+	}
+
+	spin_lock(&call->lock);
+
+	while (before(call->tx_hard_ack, to)) {
+		call->tx_hard_ack++;
+		ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
+		skb = call->rxtx_buffer[ix];
+		annotation = call->rxtx_annotations[ix];
+		rxrpc_see_skb(skb, rxrpc_skb_rotated);
+		call->rxtx_buffer[ix] = NULL;
+		call->rxtx_annotations[ix] = 0;
+		skb->next = list;
+		list = skb;
+
+		if (annotation & RXRPC_TX_ANNO_LAST) {
+			set_bit(RXRPC_CALL_TX_LAST, &call->flags);
+			rot_last = true;
+		}
+		if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
+			summary->nr_rot_new_acks++;
+	}
+
+	spin_unlock(&call->lock);
+
+	trace_rxrpc_transmit(call, (rot_last ?
+				    rxrpc_transmit_rotate_last :
+				    rxrpc_transmit_rotate));
+	wake_up(&call->waitq);
+
+	while (list) {
+		skb = list;
+		list = skb->next;
+		skb_mark_not_on_list(skb);
+		rxrpc_free_skb(skb, rxrpc_skb_freed);
+	}
+
+	return rot_last;
+}
+
+/*
+ * End the transmission phase of a call.
+ *
+ * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
+ * or a final ACK packet.
+ */
+static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
+			       const char *abort_why)
+{
+	unsigned int state;
+
+	ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
+
+	write_lock(&call->state_lock);
+
+	state = call->state;
+	switch (state) {
+	case RXRPC_CALL_CLIENT_SEND_REQUEST:
+	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
+		if (reply_begun)
+			call->state = state = RXRPC_CALL_CLIENT_RECV_REPLY;
+		else
+			call->state = state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
+		break;
+
+	case RXRPC_CALL_SERVER_AWAIT_ACK:
+		__rxrpc_call_completed(call);
+		state = call->state;
+		break;
+
+	default:
+		goto bad_state;
+	}
+
+	write_unlock(&call->state_lock);
+	if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
+		trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
+	else
+		trace_rxrpc_transmit(call, rxrpc_transmit_end);
+	_leave(" = ok");
+	return true;
+
+bad_state:
+	write_unlock(&call->state_lock);
+	kdebug("end_tx %s", rxrpc_call_states[call->state]);
+	rxrpc_proto_abort(abort_why, call, call->tx_top);
+	return false;
+}
+
+/*
+ * Begin the reply reception phase of a call.
+ */
+static bool rxrpc_receiving_reply(struct rxrpc_call *call)
+{
+	struct rxrpc_ack_summary summary = { 0 };
+	unsigned long now, timo;
+	rxrpc_seq_t top = READ_ONCE(call->tx_top);
+
+	if (call->ackr_reason) {
+		spin_lock_bh(&call->lock);
+		call->ackr_reason = 0;
+		spin_unlock_bh(&call->lock);
+		now = jiffies;
+		timo = now + MAX_JIFFY_OFFSET;
+		WRITE_ONCE(call->resend_at, timo);
+		WRITE_ONCE(call->ack_at, timo);
+		trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
+	}
+
+	if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
+		if (!rxrpc_rotate_tx_window(call, top, &summary)) {
+			rxrpc_proto_abort("TXL", call, top);
+			return false;
+		}
+	}
+	if (!rxrpc_end_tx_phase(call, true, "ETD"))
+		return false;
+	call->tx_phase = false;
+	return true;
+}
+
+/*
+ * Scan a data packet to validate its structure and to work out how many
+ * subpackets it contains.
+ *
+ * A jumbo packet is a collection of consecutive packets glued together with
+ * little headers between that indicate how to change the initial header for
+ * each subpacket.
+ *
+ * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
+ * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
+ * size.
+ */
+static bool rxrpc_validate_data(struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	unsigned int offset = sizeof(struct rxrpc_wire_header);
+	unsigned int len = skb->len;
+	u8 flags = sp->hdr.flags;
+
+	for (;;) {
+		if (flags & RXRPC_REQUEST_ACK)
+			__set_bit(sp->nr_subpackets, sp->rx_req_ack);
+		sp->nr_subpackets++;
+
+		if (!(flags & RXRPC_JUMBO_PACKET))
+			break;
+
+		if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
+			goto protocol_error;
+		if (flags & RXRPC_LAST_PACKET)
+			goto protocol_error;
+		offset += RXRPC_JUMBO_DATALEN;
+		if (skb_copy_bits(skb, offset, &flags, 1) < 0)
+			goto protocol_error;
+		offset += sizeof(struct rxrpc_jumbo_header);
+	}
+
+	if (flags & RXRPC_LAST_PACKET)
+		sp->rx_flags |= RXRPC_SKB_INCL_LAST;
+	return true;
+
+protocol_error:
+	return false;
+}
+
+/*
+ * Handle reception of a duplicate packet.
+ *
+ * We have to take care to avoid an attack here whereby we're given a series of
+ * jumbograms, each with a sequence number one before the preceding one and
+ * filled up to maximum UDP size.  If they never send us the first packet in
+ * the sequence, they can cause us to have to hold on to around 2MiB of kernel
+ * space until the call times out.
+ *
+ * We limit the space usage by only accepting three duplicate jumbo packets per
+ * call.  After that, we tell the other side we're no longer accepting jumbos
+ * (that information is encoded in the ACK packet).
+ */
+static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
+				 bool is_jumbo, bool *_jumbo_bad)
+{
+	/* Discard normal packets that are duplicates. */
+	if (is_jumbo)
+		return;
+
+	/* Skip jumbo subpackets that are duplicates.  When we've had three or
+	 * more partially duplicate jumbo packets, we refuse to take any more
+	 * jumbos for this call.
+	 */
+	if (!*_jumbo_bad) {
+		call->nr_jumbo_bad++;
+		*_jumbo_bad = true;
+	}
+}
+
+/*
+ * Process a DATA packet, adding the packet to the Rx ring.  The caller's
+ * packet ref must be passed on or discarded.
+ */
+static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	enum rxrpc_call_state state;
+	unsigned int j, nr_subpackets, nr_unacked = 0;
+	rxrpc_serial_t serial = sp->hdr.serial, ack_serial = serial;
+	rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
+	bool immediate_ack = false, jumbo_bad = false;
+	u8 ack = 0;
+
+	_enter("{%u,%u},{%u,%u}",
+	       call->rx_hard_ack, call->rx_top, skb->len, seq0);
+
+	_proto("Rx DATA %%%u { #%u f=%02x n=%u }",
+	       sp->hdr.serial, seq0, sp->hdr.flags, sp->nr_subpackets);
+
+	state = READ_ONCE(call->state);
+	if (state >= RXRPC_CALL_COMPLETE) {
+		rxrpc_free_skb(skb, rxrpc_skb_freed);
+		return;
+	}
+
+	if (state == RXRPC_CALL_SERVER_RECV_REQUEST) {
+		unsigned long timo = READ_ONCE(call->next_req_timo);
+		unsigned long now, expect_req_by;
+
+		if (timo) {
+			now = jiffies;
+			expect_req_by = now + timo;
+			WRITE_ONCE(call->expect_req_by, expect_req_by);
+			rxrpc_reduce_call_timer(call, expect_req_by, now,
+						rxrpc_timer_set_for_idle);
+		}
+	}
+
+	spin_lock(&call->input_lock);
+
+	/* Received data implicitly ACKs all of the request packets we sent
+	 * when we're acting as a client.
+	 */
+	if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
+	     state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
+	    !rxrpc_receiving_reply(call))
+		goto unlock;
+
+	hard_ack = READ_ONCE(call->rx_hard_ack);
+
+	nr_subpackets = sp->nr_subpackets;
+	if (nr_subpackets > 1) {
+		if (call->nr_jumbo_bad > 3) {
+			ack = RXRPC_ACK_NOSPACE;
+			ack_serial = serial;
+			goto ack;
+		}
+	}
+
+	for (j = 0; j < nr_subpackets; j++) {
+		rxrpc_serial_t serial = sp->hdr.serial + j;
+		rxrpc_seq_t seq = seq0 + j;
+		unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK;
+		bool terminal = (j == nr_subpackets - 1);
+		bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST);
+		u8 flags, annotation = j;
+
+		_proto("Rx DATA+%u %%%u { #%x t=%u l=%u }",
+		     j, serial, seq, terminal, last);
+
+		if (last) {
+			if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
+			    seq != call->rx_top) {
+				rxrpc_proto_abort("LSN", call, seq);
+				goto unlock;
+			}
+		} else {
+			if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
+			    after_eq(seq, call->rx_top)) {
+				rxrpc_proto_abort("LSA", call, seq);
+				goto unlock;
+			}
+		}
+
+		flags = 0;
+		if (last)
+			flags |= RXRPC_LAST_PACKET;
+		if (!terminal)
+			flags |= RXRPC_JUMBO_PACKET;
+		if (test_bit(j, sp->rx_req_ack))
+			flags |= RXRPC_REQUEST_ACK;
+		trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
+
+		if (before_eq(seq, hard_ack)) {
+			ack = RXRPC_ACK_DUPLICATE;
+			ack_serial = serial;
+			continue;
+		}
+
+		if (call->rxtx_buffer[ix]) {
+			rxrpc_input_dup_data(call, seq, nr_subpackets > 1,
+					     &jumbo_bad);
+			if (ack != RXRPC_ACK_DUPLICATE) {
+				ack = RXRPC_ACK_DUPLICATE;
+				ack_serial = serial;
+			}
+			immediate_ack = true;
+			continue;
+		}
+
+		if (after(seq, hard_ack + call->rx_winsize)) {
+			ack = RXRPC_ACK_EXCEEDS_WINDOW;
+			ack_serial = serial;
+			if (flags & RXRPC_JUMBO_PACKET) {
+				if (!jumbo_bad) {
+					call->nr_jumbo_bad++;
+					jumbo_bad = true;
+				}
+			}
+
+			goto ack;
+		}
+
+		if (flags & RXRPC_REQUEST_ACK && !ack) {
+			ack = RXRPC_ACK_REQUESTED;
+			ack_serial = serial;
+		}
+
+		if (after(seq0, call->ackr_highest_seq))
+			call->ackr_highest_seq = seq0;
+
+		/* Queue the packet.  We use a couple of memory barriers here as need
+		 * to make sure that rx_top is perceived to be set after the buffer
+		 * pointer and that the buffer pointer is set after the annotation and
+		 * the skb data.
+		 *
+		 * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
+		 * and also rxrpc_fill_out_ack().
+		 */
+		if (!terminal)
+			rxrpc_get_skb(skb, rxrpc_skb_got);
+		call->rxtx_annotations[ix] = annotation;
+		smp_wmb();
+		call->rxtx_buffer[ix] = skb;
+		if (after(seq, call->rx_top)) {
+			smp_store_release(&call->rx_top, seq);
+		} else if (before(seq, call->rx_top)) {
+			/* Send an immediate ACK if we fill in a hole */
+			if (!ack) {
+				ack = RXRPC_ACK_DELAY;
+				ack_serial = serial;
+			}
+			immediate_ack = true;
+		}
+
+		if (terminal) {
+			/* From this point on, we're not allowed to touch the
+			 * packet any longer as its ref now belongs to the Rx
+			 * ring.
+			 */
+			skb = NULL;
+			sp = NULL;
+		}
+
+		nr_unacked++;
+
+		if (last) {
+			set_bit(RXRPC_CALL_RX_LAST, &call->flags);
+			if (!ack) {
+				ack = RXRPC_ACK_DELAY;
+				ack_serial = serial;
+			}
+			trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
+		} else {
+			trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
+		}
+
+		if (after_eq(seq, call->rx_expect_next)) {
+			if (after(seq, call->rx_expect_next)) {
+				_net("OOS %u > %u", seq, call->rx_expect_next);
+				ack = RXRPC_ACK_OUT_OF_SEQUENCE;
+				ack_serial = serial;
+			}
+			call->rx_expect_next = seq + 1;
+		}
+		if (!ack)
+			ack_serial = serial;
+	}
+
+ack:
+	if (atomic_add_return(nr_unacked, &call->ackr_nr_unacked) > 2 && !ack)
+		ack = RXRPC_ACK_IDLE;
+
+	if (ack)
+		rxrpc_propose_ACK(call, ack, ack_serial,
+				  immediate_ack, true,
+				  rxrpc_propose_ack_input_data);
+	else
+		rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
+				  false, true,
+				  rxrpc_propose_ack_input_data);
+
+	trace_rxrpc_notify_socket(call->debug_id, serial);
+	rxrpc_notify_socket(call);
+
+unlock:
+	spin_unlock(&call->input_lock);
+	rxrpc_free_skb(skb, rxrpc_skb_freed);
+	_leave(" [queued]");
+}
+
+/*
+ * See if there's a cached RTT probe to complete.
+ */
+static void rxrpc_complete_rtt_probe(struct rxrpc_call *call,
+				     ktime_t resp_time,
+				     rxrpc_serial_t acked_serial,
+				     rxrpc_serial_t ack_serial,
+				     enum rxrpc_rtt_rx_trace type)
+{
+	rxrpc_serial_t orig_serial;
+	unsigned long avail;
+	ktime_t sent_at;
+	bool matched = false;
+	int i;
+
+	avail = READ_ONCE(call->rtt_avail);
+	smp_rmb(); /* Read avail bits before accessing data. */
+
+	for (i = 0; i < ARRAY_SIZE(call->rtt_serial); i++) {
+		if (!test_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &avail))
+			continue;
+
+		sent_at = call->rtt_sent_at[i];
+		orig_serial = call->rtt_serial[i];
+
+		if (orig_serial == acked_serial) {
+			clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
+			smp_mb(); /* Read data before setting avail bit */
+			set_bit(i, &call->rtt_avail);
+			if (type != rxrpc_rtt_rx_cancel)
+				rxrpc_peer_add_rtt(call, type, i, acked_serial, ack_serial,
+						   sent_at, resp_time);
+			else
+				trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_cancel, i,
+						   orig_serial, acked_serial, 0, 0);
+			matched = true;
+		}
+
+		/* If a later serial is being acked, then mark this slot as
+		 * being available.
+		 */
+		if (after(acked_serial, orig_serial)) {
+			trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_obsolete, i,
+					   orig_serial, acked_serial, 0, 0);
+			clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
+			smp_wmb();
+			set_bit(i, &call->rtt_avail);
+		}
+	}
+
+	if (!matched)
+		trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_lost, 9, 0, acked_serial, 0, 0);
+}
+
+/*
+ * Process the response to a ping that we sent to find out if we lost an ACK.
+ *
+ * If we got back a ping response that indicates a lower tx_top than what we
+ * had at the time of the ping transmission, we adjudge all the DATA packets
+ * sent between the response tx_top and the ping-time tx_top to have been lost.
+ */
+static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
+{
+	rxrpc_seq_t top, bottom, seq;
+	bool resend = false;
+
+	spin_lock_bh(&call->lock);
+
+	bottom = call->tx_hard_ack + 1;
+	top = call->acks_lost_top;
+	if (before(bottom, top)) {
+		for (seq = bottom; before_eq(seq, top); seq++) {
+			int ix = seq & RXRPC_RXTX_BUFF_MASK;
+			u8 annotation = call->rxtx_annotations[ix];
+			u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
+
+			if (anno_type != RXRPC_TX_ANNO_UNACK)
+				continue;
+			annotation &= ~RXRPC_TX_ANNO_MASK;
+			annotation |= RXRPC_TX_ANNO_RETRANS;
+			call->rxtx_annotations[ix] = annotation;
+			resend = true;
+		}
+	}
+
+	spin_unlock_bh(&call->lock);
+
+	if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
+		rxrpc_queue_call(call);
+}
+
+/*
+ * Process a ping response.
+ */
+static void rxrpc_input_ping_response(struct rxrpc_call *call,
+				      ktime_t resp_time,
+				      rxrpc_serial_t acked_serial,
+				      rxrpc_serial_t ack_serial)
+{
+	if (acked_serial == call->acks_lost_ping)
+		rxrpc_input_check_for_lost_ack(call);
+}
+
+/*
+ * Process the extra information that may be appended to an ACK packet
+ */
+static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
+				struct rxrpc_ackinfo *ackinfo)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	struct rxrpc_peer *peer;
+	unsigned int mtu;
+	bool wake = false;
+	u32 rwind = ntohl(ackinfo->rwind);
+
+	_proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
+	       sp->hdr.serial,
+	       ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
+	       rwind, ntohl(ackinfo->jumbo_max));
+
+	if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
+		rwind = RXRPC_RXTX_BUFF_SIZE - 1;
+	if (call->tx_winsize != rwind) {
+		if (rwind > call->tx_winsize)
+			wake = true;
+		trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
+		call->tx_winsize = rwind;
+	}
+
+	if (call->cong_ssthresh > rwind)
+		call->cong_ssthresh = rwind;
+
+	mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
+
+	peer = call->peer;
+	if (mtu < peer->maxdata) {
+		spin_lock_bh(&peer->lock);
+		peer->maxdata = mtu;
+		peer->mtu = mtu + peer->hdrsize;
+		spin_unlock_bh(&peer->lock);
+		_net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
+	}
+
+	if (wake)
+		wake_up(&call->waitq);
+}
+
+/*
+ * Process individual soft ACKs.
+ *
+ * Each ACK in the array corresponds to one packet and can be either an ACK or
+ * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
+ * packets that lie beyond the end of the ACK list are scheduled for resend by
+ * the timer on the basis that the peer might just not have processed them at
+ * the time the ACK was sent.
+ */
+static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
+				  rxrpc_seq_t seq, int nr_acks,
+				  struct rxrpc_ack_summary *summary)
+{
+	int ix;
+	u8 annotation, anno_type;
+
+	for (; nr_acks > 0; nr_acks--, seq++) {
+		ix = seq & RXRPC_RXTX_BUFF_MASK;
+		annotation = call->rxtx_annotations[ix];
+		anno_type = annotation & RXRPC_TX_ANNO_MASK;
+		annotation &= ~RXRPC_TX_ANNO_MASK;
+		switch (*acks++) {
+		case RXRPC_ACK_TYPE_ACK:
+			summary->nr_acks++;
+			if (anno_type == RXRPC_TX_ANNO_ACK)
+				continue;
+			summary->nr_new_acks++;
+			call->rxtx_annotations[ix] =
+				RXRPC_TX_ANNO_ACK | annotation;
+			break;
+		case RXRPC_ACK_TYPE_NACK:
+			if (!summary->nr_nacks &&
+			    call->acks_lowest_nak != seq) {
+				call->acks_lowest_nak = seq;
+				summary->new_low_nack = true;
+			}
+			summary->nr_nacks++;
+			if (anno_type == RXRPC_TX_ANNO_NAK)
+				continue;
+			summary->nr_new_nacks++;
+			if (anno_type == RXRPC_TX_ANNO_RETRANS)
+				continue;
+			call->rxtx_annotations[ix] =
+				RXRPC_TX_ANNO_NAK | annotation;
+			break;
+		default:
+			return rxrpc_proto_abort("SFT", call, 0);
+		}
+	}
+}
+
+/*
+ * Return true if the ACK is valid - ie. it doesn't appear to have regressed
+ * with respect to the ack state conveyed by preceding ACKs.
+ */
+static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
+			       rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
+{
+	rxrpc_seq_t base = READ_ONCE(call->acks_first_seq);
+
+	if (after(first_pkt, base))
+		return true; /* The window advanced */
+
+	if (before(first_pkt, base))
+		return false; /* firstPacket regressed */
+
+	if (after_eq(prev_pkt, call->acks_prev_seq))
+		return true; /* previousPacket hasn't regressed. */
+
+	/* Some rx implementations put a serial number in previousPacket. */
+	if (after_eq(prev_pkt, base + call->tx_winsize))
+		return false;
+	return true;
+}
+
+/*
+ * Process an ACK packet.
+ *
+ * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
+ * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
+ *
+ * A hard-ACK means that a packet has been processed and may be discarded; a
+ * soft-ACK means that the packet may be discarded and retransmission
+ * requested.  A phase is complete when all packets are hard-ACK'd.
+ */
+static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
+{
+	struct rxrpc_ack_summary summary = { 0 };
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	union {
+		struct rxrpc_ackpacket ack;
+		struct rxrpc_ackinfo info;
+		u8 acks[RXRPC_MAXACKS];
+	} buf;
+	rxrpc_serial_t ack_serial, acked_serial;
+	rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
+	int nr_acks, offset, ioffset;
+
+	_enter("");
+
+	offset = sizeof(struct rxrpc_wire_header);
+	if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
+		_debug("extraction failure");
+		return rxrpc_proto_abort("XAK", call, 0);
+	}
+	offset += sizeof(buf.ack);
+
+	ack_serial = sp->hdr.serial;
+	acked_serial = ntohl(buf.ack.serial);
+	first_soft_ack = ntohl(buf.ack.firstPacket);
+	prev_pkt = ntohl(buf.ack.previousPacket);
+	hard_ack = first_soft_ack - 1;
+	nr_acks = buf.ack.nAcks;
+	summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
+			      buf.ack.reason : RXRPC_ACK__INVALID);
+
+	trace_rxrpc_rx_ack(call, ack_serial, acked_serial,
+			   first_soft_ack, prev_pkt,
+			   summary.ack_reason, nr_acks);
+
+	switch (buf.ack.reason) {
+	case RXRPC_ACK_PING_RESPONSE:
+		rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
+					  ack_serial);
+		rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
+					 rxrpc_rtt_rx_ping_response);
+		break;
+	case RXRPC_ACK_REQUESTED:
+		rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
+					 rxrpc_rtt_rx_requested_ack);
+		break;
+	default:
+		if (acked_serial != 0)
+			rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
+						 rxrpc_rtt_rx_cancel);
+		break;
+	}
+
+	if (buf.ack.reason == RXRPC_ACK_PING) {
+		_proto("Rx ACK %%%u PING Request", ack_serial);
+		rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
+				  ack_serial, true, true,
+				  rxrpc_propose_ack_respond_to_ping);
+	} else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
+		rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
+				  ack_serial, true, true,
+				  rxrpc_propose_ack_respond_to_ack);
+	}
+
+	/* Discard any out-of-order or duplicate ACKs (outside lock). */
+	if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
+		trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
+					   first_soft_ack, call->acks_first_seq,
+					   prev_pkt, call->acks_prev_seq);
+		return;
+	}
+
+	buf.info.rxMTU = 0;
+	ioffset = offset + nr_acks + 3;
+	if (skb->len >= ioffset + sizeof(buf.info) &&
+	    skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
+		return rxrpc_proto_abort("XAI", call, 0);
+
+	spin_lock(&call->input_lock);
+
+	/* Discard any out-of-order or duplicate ACKs (inside lock). */
+	if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
+		trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
+					   first_soft_ack, call->acks_first_seq,
+					   prev_pkt, call->acks_prev_seq);
+		goto out;
+	}
+	call->acks_latest_ts = skb->tstamp;
+
+	call->acks_first_seq = first_soft_ack;
+	call->acks_prev_seq = prev_pkt;
+
+	/* Parse rwind and mtu sizes if provided. */
+	if (buf.info.rxMTU)
+		rxrpc_input_ackinfo(call, skb, &buf.info);
+
+	if (first_soft_ack == 0) {
+		rxrpc_proto_abort("AK0", call, 0);
+		goto out;
+	}
+
+	/* Ignore ACKs unless we are or have just been transmitting. */
+	switch (READ_ONCE(call->state)) {
+	case RXRPC_CALL_CLIENT_SEND_REQUEST:
+	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
+	case RXRPC_CALL_SERVER_SEND_REPLY:
+	case RXRPC_CALL_SERVER_AWAIT_ACK:
+		break;
+	default:
+		goto out;
+	}
+
+	if (before(hard_ack, call->tx_hard_ack) ||
+	    after(hard_ack, call->tx_top)) {
+		rxrpc_proto_abort("AKW", call, 0);
+		goto out;
+	}
+	if (nr_acks > call->tx_top - hard_ack) {
+		rxrpc_proto_abort("AKN", call, 0);
+		goto out;
+	}
+
+	if (after(hard_ack, call->tx_hard_ack)) {
+		if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
+			rxrpc_end_tx_phase(call, false, "ETA");
+			goto out;
+		}
+	}
+
+	if (nr_acks > 0) {
+		if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
+			rxrpc_proto_abort("XSA", call, 0);
+			goto out;
+		}
+		rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
+				      &summary);
+	}
+
+	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
+	    RXRPC_TX_ANNO_LAST &&
+	    summary.nr_acks == call->tx_top - hard_ack &&
+	    rxrpc_is_client_call(call))
+		rxrpc_propose_ACK(call, RXRPC_ACK_PING, ack_serial,
+				  false, true,
+				  rxrpc_propose_ack_ping_for_lost_reply);
+
+	rxrpc_congestion_management(call, skb, &summary, acked_serial);
+out:
+	spin_unlock(&call->input_lock);
+}
+
+/*
+ * Process an ACKALL packet.
+ */
+static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
+{
+	struct rxrpc_ack_summary summary = { 0 };
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+
+	_proto("Rx ACKALL %%%u", sp->hdr.serial);
+
+	spin_lock(&call->input_lock);
+
+	if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
+		rxrpc_end_tx_phase(call, false, "ETL");
+
+	spin_unlock(&call->input_lock);
+}
+
+/*
+ * Process an ABORT packet directed at a call.
+ */
+static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	__be32 wtmp;
+	u32 abort_code = RX_CALL_DEAD;
+
+	_enter("");
+
+	if (skb->len >= 4 &&
+	    skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
+			  &wtmp, sizeof(wtmp)) >= 0)
+		abort_code = ntohl(wtmp);
+
+	trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
+
+	_proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
+
+	rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
+				  abort_code, -ECONNABORTED);
+}
+
+/*
+ * Process an incoming call packet.
+ */
+static void rxrpc_input_call_packet(struct rxrpc_call *call,
+				    struct sk_buff *skb)
+{
+	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
+	unsigned long timo;
+
+	_enter("%p,%p", call, skb);
+
+	timo = READ_ONCE(call->next_rx_timo);
+	if (timo) {
+		unsigned long now = jiffies, expect_rx_by;
+
+		expect_rx_by = now + timo;
+		WRITE_ONCE(call->expect_rx_by, expect_rx_by);
+		rxrpc_reduce_call_timer(call, expect_rx_by, now,
+					rxrpc_timer_set_for_normal);
+	}
+
+	switch (sp->hdr.type) {
+	case RXRPC_PACKET_TYPE_DATA:
+		rxrpc_input_data(call, skb);
+		goto no_free;
+
+	case RXRPC_PACKET_TYPE_ACK:
+		rxrpc_input_ack(call, skb);
+		break;
+
+	case RXRPC_PACKET_TYPE_BUSY:
+		_proto("Rx BUSY %%%u", sp->hdr.serial);
+
+		/* Just ignore BUSY packets from the server; the retry and
+		 * lifespan timers will take care of business.  BUSY packets
+		 * from the client don't make sense.
+		 */
+		break;
+
+	case RXRPC_PACKET_TYPE_ABORT:
+		rxrpc_input_abort(call, skb);
+		break;
+
+	case RXRPC_PACKET_TYPE_ACKALL:
+		rxrpc_input_ackall(call, skb);
+		break;
+
+	default:
+		break;
+	}
+
+	rxrpc_free_skb(skb, rxrpc_skb_freed);
+no_free:
+	_leave("");
+}
+
+/*
+ * Handle a new service call on a channel implicitly completing the preceding
+ * call on that channel.  This does not apply to client conns.
+ *
+ * TODO: If callNumber > call_id + 1, renegotiate security.
+ */
+static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
+					  struct rxrpc_connection *conn,
+					  struct rxrpc_call *call)
+{
+	switch (READ_ONCE(call->state)) {
+	case RXRPC_CALL_SERVER_AWAIT_ACK:
+		rxrpc_call_completed(call);
+		fallthrough;
+	case RXRPC_CALL_COMPLETE:
+		break;
+	default:
+		if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
+			set_bit(RXRPC_CALL_EV_ABORT, &call->events);
+			rxrpc_queue_call(call);
+		}
+		trace_rxrpc_improper_term(call);
+		break;
+	}
+
+	spin_lock(&rx->incoming_lock);
+	__rxrpc_disconnect_call(conn, call);
+	spin_unlock(&rx->incoming_lock);
+}
+
+/*
+ * post connection-level events to the connection
+ * - this includes challenges, responses, some aborts and call terminal packet
+ *   retransmission.
+ */
+static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
+				      struct sk_buff *skb)
+{
+	_enter("%p,%p", conn, skb);
+
+	skb_queue_tail(&conn->rx_queue, skb);
+	rxrpc_queue_conn(conn);
+}
+
+/*
+ * post endpoint-level events to the local endpoint
+ * - this includes debug and version messages
+ */
+static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
+				       struct sk_buff *skb)
+{
+	_enter("%p,%p", local, skb);
+
+	if (rxrpc_get_local_maybe(local)) {
+		skb_queue_tail(&local->event_queue, skb);
+		rxrpc_queue_local(local);
+	} else {
+		rxrpc_free_skb(skb, rxrpc_skb_freed);
+	}
+}
+
+/*
+ * put a packet up for transport-level abort
+ */
+static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
+{
+	if (rxrpc_get_local_maybe(local)) {
+		skb_queue_tail(&local->reject_queue, skb);
+		rxrpc_queue_local(local);
+	} else {
+		rxrpc_free_skb(skb, rxrpc_skb_freed);
+	}
+}
+
+/*
+ * Extract the wire header from a packet and translate the byte order.
+ */
+static noinline
+int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
+{
+	struct rxrpc_wire_header whdr;
+
+	/* dig out the RxRPC connection details */
+	if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
+		trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
+				      tracepoint_string("bad_hdr"));
+		return -EBADMSG;
+	}
+
+	memset(sp, 0, sizeof(*sp));
+	sp->hdr.epoch		= ntohl(whdr.epoch);
+	sp->hdr.cid		= ntohl(whdr.cid);
+	sp->hdr.callNumber	= ntohl(whdr.callNumber);
+	sp->hdr.seq		= ntohl(whdr.seq);
+	sp->hdr.serial		= ntohl(whdr.serial);
+	sp->hdr.flags		= whdr.flags;
+	sp->hdr.type		= whdr.type;
+	sp->hdr.userStatus	= whdr.userStatus;
+	sp->hdr.securityIndex	= whdr.securityIndex;
+	sp->hdr._rsvd		= ntohs(whdr._rsvd);
+	sp->hdr.serviceId	= ntohs(whdr.serviceId);
+	return 0;
+}
+
+/*
+ * handle data received on the local endpoint
+ * - may be called in interrupt context
+ *
+ * [!] Note that as this is called from the encap_rcv hook, the socket is not
+ * held locked by the caller and nothing prevents sk_user_data on the UDP from
+ * being cleared in the middle of processing this function.
+ *
+ * Called with the RCU read lock held from the IP layer via UDP.
+ */
+int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
+{
+	struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
+	struct rxrpc_connection *conn;
+	struct rxrpc_channel *chan;
+	struct rxrpc_call *call = NULL;
+	struct rxrpc_skb_priv *sp;
+	struct rxrpc_peer *peer = NULL;
+	struct rxrpc_sock *rx = NULL;
+	unsigned int channel;
+
+	_enter("%p", udp_sk);
+
+	if (unlikely(!local)) {
+		kfree_skb(skb);
+		return 0;
+	}
+	if (skb->tstamp == 0)
+		skb->tstamp = ktime_get_real();
+
+	rxrpc_new_skb(skb, rxrpc_skb_received);
+
+	skb_pull(skb, sizeof(struct udphdr));
+
+	/* The UDP protocol already released all skb resources;
+	 * we are free to add our own data there.
+	 */
+	sp = rxrpc_skb(skb);
+
+	/* dig out the RxRPC connection details */
+	if (rxrpc_extract_header(sp, skb) < 0)
+		goto bad_message;
+
+	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
+		static int lose;
+		if ((lose++ & 7) == 7) {
+			trace_rxrpc_rx_lose(sp);
+			rxrpc_free_skb(skb, rxrpc_skb_lost);
+			return 0;
+		}
+	}
+
+	if (skb->tstamp == 0)
+		skb->tstamp = ktime_get_real();
+	trace_rxrpc_rx_packet(sp);
+
+	switch (sp->hdr.type) {
+	case RXRPC_PACKET_TYPE_VERSION:
+		if (rxrpc_to_client(sp))
+			goto discard;
+		rxrpc_post_packet_to_local(local, skb);
+		goto out;
+
+	case RXRPC_PACKET_TYPE_BUSY:
+		if (rxrpc_to_server(sp))
+			goto discard;
+		fallthrough;
+	case RXRPC_PACKET_TYPE_ACK:
+	case RXRPC_PACKET_TYPE_ACKALL:
+		if (sp->hdr.callNumber == 0)
+			goto bad_message;
+		fallthrough;
+	case RXRPC_PACKET_TYPE_ABORT:
+		break;
+
+	case RXRPC_PACKET_TYPE_DATA:
+		if (sp->hdr.callNumber == 0 ||
+		    sp->hdr.seq == 0)
+			goto bad_message;
+		if (!rxrpc_validate_data(skb))
+			goto bad_message;
+
+		/* Unshare the packet so that it can be modified for in-place
+		 * decryption.
+		 */
+		if (sp->hdr.securityIndex != 0) {
+			struct sk_buff *nskb = skb_unshare(skb, GFP_ATOMIC);
+			if (!nskb) {
+				rxrpc_eaten_skb(skb, rxrpc_skb_unshared_nomem);
+				goto out;
+			}
+
+			if (nskb != skb) {
+				rxrpc_eaten_skb(skb, rxrpc_skb_received);
+				skb = nskb;
+				rxrpc_new_skb(skb, rxrpc_skb_unshared);
+				sp = rxrpc_skb(skb);
+			}
+		}
+		break;
+
+	case RXRPC_PACKET_TYPE_CHALLENGE:
+		if (rxrpc_to_server(sp))
+			goto discard;
+		break;
+	case RXRPC_PACKET_TYPE_RESPONSE:
+		if (rxrpc_to_client(sp))
+			goto discard;
+		break;
+
+		/* Packet types 9-11 should just be ignored. */
+	case RXRPC_PACKET_TYPE_PARAMS:
+	case RXRPC_PACKET_TYPE_10:
+	case RXRPC_PACKET_TYPE_11:
+		goto discard;
+
+	default:
+		_proto("Rx Bad Packet Type %u", sp->hdr.type);
+		goto bad_message;
+	}
+
+	if (sp->hdr.serviceId == 0)
+		goto bad_message;
+
+	if (rxrpc_to_server(sp)) {
+		/* Weed out packets to services we're not offering.  Packets
+		 * that would begin a call are explicitly rejected and the rest
+		 * are just discarded.
+		 */
+		rx = rcu_dereference(local->service);
+		if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
+			    sp->hdr.serviceId != rx->second_service)) {
+			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
+			    sp->hdr.seq == 1)
+				goto unsupported_service;
+			goto discard;
+		}
+	}
+
+	conn = rxrpc_find_connection_rcu(local, skb, &peer);
+	if (conn) {
+		if (sp->hdr.securityIndex != conn->security_ix)
+			goto wrong_security;
+
+		if (sp->hdr.serviceId != conn->service_id) {
+			int old_id;
+
+			if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
+				goto reupgrade;
+			old_id = cmpxchg(&conn->service_id, conn->params.service_id,
+					 sp->hdr.serviceId);
+
+			if (old_id != conn->params.service_id &&
+			    old_id != sp->hdr.serviceId)
+				goto reupgrade;
+		}
+
+		if (sp->hdr.callNumber == 0) {
+			/* Connection-level packet */
+			_debug("CONN %p {%d}", conn, conn->debug_id);
+			rxrpc_post_packet_to_conn(conn, skb);
+			goto out;
+		}
+
+		if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
+			conn->hi_serial = sp->hdr.serial;
+
+		/* Call-bound packets are routed by connection channel. */
+		channel = sp->hdr.cid & RXRPC_CHANNELMASK;
+		chan = &conn->channels[channel];
+
+		/* Ignore really old calls */
+		if (sp->hdr.callNumber < chan->last_call)
+			goto discard;
+
+		if (sp->hdr.callNumber == chan->last_call) {
+			if (chan->call ||
+			    sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
+				goto discard;
+
+			/* For the previous service call, if completed
+			 * successfully, we discard all further packets.
+			 */
+			if (rxrpc_conn_is_service(conn) &&
+			    chan->last_type == RXRPC_PACKET_TYPE_ACK)
+				goto discard;
+
+			/* But otherwise we need to retransmit the final packet
+			 * from data cached in the connection record.
+			 */
+			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
+				trace_rxrpc_rx_data(chan->call_debug_id,
+						    sp->hdr.seq,
+						    sp->hdr.serial,
+						    sp->hdr.flags, 0);
+			rxrpc_post_packet_to_conn(conn, skb);
+			goto out;
+		}
+
+		call = rcu_dereference(chan->call);
+
+		if (sp->hdr.callNumber > chan->call_id) {
+			if (rxrpc_to_client(sp))
+				goto reject_packet;
+			if (call)
+				rxrpc_input_implicit_end_call(rx, conn, call);
+			call = NULL;
+		}
+
+		if (call) {
+			if (sp->hdr.serviceId != call->service_id)
+				call->service_id = sp->hdr.serviceId;
+			if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
+				call->rx_serial = sp->hdr.serial;
+			if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
+				set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
+		}
+	}
+
+	if (!call || refcount_read(&call->ref) == 0) {
+		if (rxrpc_to_client(sp) ||
+		    sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
+			goto bad_message;
+		if (sp->hdr.seq != 1)
+			goto discard;
+		call = rxrpc_new_incoming_call(local, rx, skb);
+		if (!call)
+			goto reject_packet;
+	}
+
+	/* Process a call packet; this either discards or passes on the ref
+	 * elsewhere.
+	 */
+	rxrpc_input_call_packet(call, skb);
+	goto out;
+
+discard:
+	rxrpc_free_skb(skb, rxrpc_skb_freed);
+out:
+	trace_rxrpc_rx_done(0, 0);
+	return 0;
+
+wrong_security:
+	trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+			  RXKADINCONSISTENCY, EBADMSG);
+	skb->priority = RXKADINCONSISTENCY;
+	goto post_abort;
+
+unsupported_service:
+	trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+			  RX_INVALID_OPERATION, EOPNOTSUPP);
+	skb->priority = RX_INVALID_OPERATION;
+	goto post_abort;
+
+reupgrade:
+	trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+			  RX_PROTOCOL_ERROR, EBADMSG);
+	goto protocol_error;
+
+bad_message:
+	trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
+			  RX_PROTOCOL_ERROR, EBADMSG);
+protocol_error:
+	skb->priority = RX_PROTOCOL_ERROR;
+post_abort:
+	skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
+reject_packet:
+	trace_rxrpc_rx_done(skb->mark, skb->priority);
+	rxrpc_reject_packet(local, skb);
+	_leave(" [badmsg]");
+	return 0;
+}