Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 1349 insertions, 0 deletions

diff --git a/net/sctp/input.c b/net/sctp/input.c
new file mode 100644
index 000000000..4f43afa86
--- /dev/null
+++ b/net/sctp/input.c
@@ -0,0 +1,1349 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SCTP kernel implementation
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 International Business Machines, Corp.
+ * Copyright (c) 2001 Intel Corp.
+ * Copyright (c) 2001 Nokia, Inc.
+ * Copyright (c) 2001 La Monte H.P. Yarroll
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * These functions handle all input from the IP layer into SCTP.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    La Monte H.P. Yarroll <piggy@acm.org>
+ *    Karl Knutson <karl@athena.chicago.il.us>
+ *    Xingang Guo <xingang.guo@intel.com>
+ *    Jon Grimm <jgrimm@us.ibm.com>
+ *    Hui Huang <hui.huang@nokia.com>
+ *    Daisy Chang <daisyc@us.ibm.com>
+ *    Sridhar Samudrala <sri@us.ibm.com>
+ *    Ardelle Fan <ardelle.fan@intel.com>
+ */
+
+#include <linux/types.h>
+#include <linux/list.h> /* For struct list_head */
+#include <linux/socket.h>
+#include <linux/ip.h>
+#include <linux/time.h> /* For struct timeval */
+#include <linux/slab.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/snmp.h>
+#include <net/sock.h>
+#include <net/xfrm.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+#include <net/sctp/checksum.h>
+#include <net/net_namespace.h>
+#include <linux/rhashtable.h>
+#include <net/sock_reuseport.h>
+
+/* Forward declarations for internal helpers. */
+static int sctp_rcv_ootb(struct sk_buff *);
+static struct sctp_association *__sctp_rcv_lookup(struct net *net,
+				      struct sk_buff *skb,
+				      const union sctp_addr *paddr,
+				      const union sctp_addr *laddr,
+				      struct sctp_transport **transportp);
+static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
+					struct net *net, struct sk_buff *skb,
+					const union sctp_addr *laddr,
+					const union sctp_addr *daddr);
+static struct sctp_association *__sctp_lookup_association(
+					struct net *net,
+					const union sctp_addr *local,
+					const union sctp_addr *peer,
+					struct sctp_transport **pt);
+
+static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
+
+
+/* Calculate the SCTP checksum of an SCTP packet.  */
+static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
+{
+	struct sctphdr *sh = sctp_hdr(skb);
+	__le32 cmp = sh->checksum;
+	__le32 val = sctp_compute_cksum(skb, 0);
+
+	if (val != cmp) {
+		/* CRC failure, dump it. */
+		__SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
+		return -1;
+	}
+	return 0;
+}
+
+/*
+ * This is the routine which IP calls when receiving an SCTP packet.
+ */
+int sctp_rcv(struct sk_buff *skb)
+{
+	struct sock *sk;
+	struct sctp_association *asoc;
+	struct sctp_endpoint *ep = NULL;
+	struct sctp_ep_common *rcvr;
+	struct sctp_transport *transport = NULL;
+	struct sctp_chunk *chunk;
+	union sctp_addr src;
+	union sctp_addr dest;
+	int bound_dev_if;
+	int family;
+	struct sctp_af *af;
+	struct net *net = dev_net(skb->dev);
+	bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb);
+
+	if (skb->pkt_type != PACKET_HOST)
+		goto discard_it;
+
+	__SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
+
+	/* If packet is too small to contain a single chunk, let's not
+	 * waste time on it anymore.
+	 */
+	if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) +
+		       skb_transport_offset(skb))
+		goto discard_it;
+
+	/* If the packet is fragmented and we need to do crc checking,
+	 * it's better to just linearize it otherwise crc computing
+	 * takes longer.
+	 */
+	if ((!is_gso && skb_linearize(skb)) ||
+	    !pskb_may_pull(skb, sizeof(struct sctphdr)))
+		goto discard_it;
+
+	/* Pull up the IP header. */
+	__skb_pull(skb, skb_transport_offset(skb));
+
+	skb->csum_valid = 0; /* Previous value not applicable */
+	if (skb_csum_unnecessary(skb))
+		__skb_decr_checksum_unnecessary(skb);
+	else if (!sctp_checksum_disable &&
+		 !is_gso &&
+		 sctp_rcv_checksum(net, skb) < 0)
+		goto discard_it;
+	skb->csum_valid = 1;
+
+	__skb_pull(skb, sizeof(struct sctphdr));
+
+	family = ipver2af(ip_hdr(skb)->version);
+	af = sctp_get_af_specific(family);
+	if (unlikely(!af))
+		goto discard_it;
+	SCTP_INPUT_CB(skb)->af = af;
+
+	/* Initialize local addresses for lookups. */
+	af->from_skb(&src, skb, 1);
+	af->from_skb(&dest, skb, 0);
+
+	/* If the packet is to or from a non-unicast address,
+	 * silently discard the packet.
+	 *
+	 * This is not clearly defined in the RFC except in section
+	 * 8.4 - OOTB handling.  However, based on the book "Stream Control
+	 * Transmission Protocol" 2.1, "It is important to note that the
+	 * IP address of an SCTP transport address must be a routable
+	 * unicast address.  In other words, IP multicast addresses and
+	 * IP broadcast addresses cannot be used in an SCTP transport
+	 * address."
+	 */
+	if (!af->addr_valid(&src, NULL, skb) ||
+	    !af->addr_valid(&dest, NULL, skb))
+		goto discard_it;
+
+	asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport);
+
+	if (!asoc)
+		ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src);
+
+	/* Retrieve the common input handling substructure. */
+	rcvr = asoc ? &asoc->base : &ep->base;
+	sk = rcvr->sk;
+
+	/*
+	 * If a frame arrives on an interface and the receiving socket is
+	 * bound to another interface, via SO_BINDTODEVICE, treat it as OOTB
+	 */
+	bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
+	if (bound_dev_if && (bound_dev_if != af->skb_iif(skb))) {
+		if (transport) {
+			sctp_transport_put(transport);
+			asoc = NULL;
+			transport = NULL;
+		} else {
+			sctp_endpoint_put(ep);
+			ep = NULL;
+		}
+		sk = net->sctp.ctl_sock;
+		ep = sctp_sk(sk)->ep;
+		sctp_endpoint_hold(ep);
+		rcvr = &ep->base;
+	}
+
+	/*
+	 * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
+	 * An SCTP packet is called an "out of the blue" (OOTB)
+	 * packet if it is correctly formed, i.e., passed the
+	 * receiver's checksum check, but the receiver is not
+	 * able to identify the association to which this
+	 * packet belongs.
+	 */
+	if (!asoc) {
+		if (sctp_rcv_ootb(skb)) {
+			__SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
+			goto discard_release;
+		}
+	}
+
+	if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
+		goto discard_release;
+	nf_reset_ct(skb);
+
+	if (sk_filter(sk, skb))
+		goto discard_release;
+
+	/* Create an SCTP packet structure. */
+	chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
+	if (!chunk)
+		goto discard_release;
+	SCTP_INPUT_CB(skb)->chunk = chunk;
+
+	/* Remember what endpoint is to handle this packet. */
+	chunk->rcvr = rcvr;
+
+	/* Remember the SCTP header. */
+	chunk->sctp_hdr = sctp_hdr(skb);
+
+	/* Set the source and destination addresses of the incoming chunk.  */
+	sctp_init_addrs(chunk, &src, &dest);
+
+	/* Remember where we came from.  */
+	chunk->transport = transport;
+
+	/* Acquire access to the sock lock. Note: We are safe from other
+	 * bottom halves on this lock, but a user may be in the lock too,
+	 * so check if it is busy.
+	 */
+	bh_lock_sock(sk);
+
+	if (sk != rcvr->sk) {
+		/* Our cached sk is different from the rcvr->sk.  This is
+		 * because migrate()/accept() may have moved the association
+		 * to a new socket and released all the sockets.  So now we
+		 * are holding a lock on the old socket while the user may
+		 * be doing something with the new socket.  Switch our veiw
+		 * of the current sk.
+		 */
+		bh_unlock_sock(sk);
+		sk = rcvr->sk;
+		bh_lock_sock(sk);
+	}
+
+	if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
+		if (sctp_add_backlog(sk, skb)) {
+			bh_unlock_sock(sk);
+			sctp_chunk_free(chunk);
+			skb = NULL; /* sctp_chunk_free already freed the skb */
+			goto discard_release;
+		}
+		__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG);
+	} else {
+		__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ);
+		sctp_inq_push(&chunk->rcvr->inqueue, chunk);
+	}
+
+	bh_unlock_sock(sk);
+
+	/* Release the asoc/ep ref we took in the lookup calls. */
+	if (transport)
+		sctp_transport_put(transport);
+	else
+		sctp_endpoint_put(ep);
+
+	return 0;
+
+discard_it:
+	__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
+	kfree_skb(skb);
+	return 0;
+
+discard_release:
+	/* Release the asoc/ep ref we took in the lookup calls. */
+	if (transport)
+		sctp_transport_put(transport);
+	else
+		sctp_endpoint_put(ep);
+
+	goto discard_it;
+}
+
+/* Process the backlog queue of the socket.  Every skb on
+ * the backlog holds a ref on an association or endpoint.
+ * We hold this ref throughout the state machine to make
+ * sure that the structure we need is still around.
+ */
+int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
+	struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
+	struct sctp_transport *t = chunk->transport;
+	struct sctp_ep_common *rcvr = NULL;
+	int backloged = 0;
+
+	rcvr = chunk->rcvr;
+
+	/* If the rcvr is dead then the association or endpoint
+	 * has been deleted and we can safely drop the chunk
+	 * and refs that we are holding.
+	 */
+	if (rcvr->dead) {
+		sctp_chunk_free(chunk);
+		goto done;
+	}
+
+	if (unlikely(rcvr->sk != sk)) {
+		/* In this case, the association moved from one socket to
+		 * another.  We are currently sitting on the backlog of the
+		 * old socket, so we need to move.
+		 * However, since we are here in the process context we
+		 * need to take make sure that the user doesn't own
+		 * the new socket when we process the packet.
+		 * If the new socket is user-owned, queue the chunk to the
+		 * backlog of the new socket without dropping any refs.
+		 * Otherwise, we can safely push the chunk on the inqueue.
+		 */
+
+		sk = rcvr->sk;
+		local_bh_disable();
+		bh_lock_sock(sk);
+
+		if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
+			if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
+				sctp_chunk_free(chunk);
+			else
+				backloged = 1;
+		} else
+			sctp_inq_push(inqueue, chunk);
+
+		bh_unlock_sock(sk);
+		local_bh_enable();
+
+		/* If the chunk was backloged again, don't drop refs */
+		if (backloged)
+			return 0;
+	} else {
+		if (!sctp_newsk_ready(sk)) {
+			if (!sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
+				return 0;
+			sctp_chunk_free(chunk);
+		} else {
+			sctp_inq_push(inqueue, chunk);
+		}
+	}
+
+done:
+	/* Release the refs we took in sctp_add_backlog */
+	if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
+		sctp_transport_put(t);
+	else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
+		sctp_endpoint_put(sctp_ep(rcvr));
+	else
+		BUG();
+
+	return 0;
+}
+
+static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
+{
+	struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
+	struct sctp_transport *t = chunk->transport;
+	struct sctp_ep_common *rcvr = chunk->rcvr;
+	int ret;
+
+	ret = sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
+	if (!ret) {
+		/* Hold the assoc/ep while hanging on the backlog queue.
+		 * This way, we know structures we need will not disappear
+		 * from us
+		 */
+		if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
+			sctp_transport_hold(t);
+		else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
+			sctp_endpoint_hold(sctp_ep(rcvr));
+		else
+			BUG();
+	}
+	return ret;
+
+}
+
+/* Handle icmp frag needed error. */
+void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
+			   struct sctp_transport *t, __u32 pmtu)
+{
+	if (!t ||
+	    (t->pathmtu <= pmtu &&
+	     t->pl.probe_size + sctp_transport_pl_hlen(t) <= pmtu))
+		return;
+
+	if (sock_owned_by_user(sk)) {
+		atomic_set(&t->mtu_info, pmtu);
+		asoc->pmtu_pending = 1;
+		t->pmtu_pending = 1;
+		return;
+	}
+
+	if (!(t->param_flags & SPP_PMTUD_ENABLE))
+		/* We can't allow retransmitting in such case, as the
+		 * retransmission would be sized just as before, and thus we
+		 * would get another icmp, and retransmit again.
+		 */
+		return;
+
+	/* Update transports view of the MTU. Return if no update was needed.
+	 * If an update wasn't needed/possible, it also doesn't make sense to
+	 * try to retransmit now.
+	 */
+	if (!sctp_transport_update_pmtu(t, pmtu))
+		return;
+
+	/* Update association pmtu. */
+	sctp_assoc_sync_pmtu(asoc);
+
+	/* Retransmit with the new pmtu setting. */
+	sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
+}
+
+void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
+			struct sk_buff *skb)
+{
+	struct dst_entry *dst;
+
+	if (sock_owned_by_user(sk) || !t)
+		return;
+	dst = sctp_transport_dst_check(t);
+	if (dst)
+		dst->ops->redirect(dst, sk, skb);
+}
+
+/*
+ * SCTP Implementer's Guide, 2.37 ICMP handling procedures
+ *
+ * ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
+ *        or a "Protocol Unreachable" treat this message as an abort
+ *        with the T bit set.
+ *
+ * This function sends an event to the state machine, which will abort the
+ * association.
+ *
+ */
+void sctp_icmp_proto_unreachable(struct sock *sk,
+			   struct sctp_association *asoc,
+			   struct sctp_transport *t)
+{
+	if (sock_owned_by_user(sk)) {
+		if (timer_pending(&t->proto_unreach_timer))
+			return;
+		else {
+			if (!mod_timer(&t->proto_unreach_timer,
+						jiffies + (HZ/20)))
+				sctp_transport_hold(t);
+		}
+	} else {
+		struct net *net = sock_net(sk);
+
+		pr_debug("%s: unrecognized next header type "
+			 "encountered!\n", __func__);
+
+		if (del_timer(&t->proto_unreach_timer))
+			sctp_transport_put(t);
+
+		sctp_do_sm(net, SCTP_EVENT_T_OTHER,
+			   SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
+			   asoc->state, asoc->ep, asoc, t,
+			   GFP_ATOMIC);
+	}
+}
+
+/* Common lookup code for icmp/icmpv6 error handler. */
+struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
+			     struct sctphdr *sctphdr,
+			     struct sctp_association **app,
+			     struct sctp_transport **tpp)
+{
+	struct sctp_init_chunk *chunkhdr, _chunkhdr;
+	union sctp_addr saddr;
+	union sctp_addr daddr;
+	struct sctp_af *af;
+	struct sock *sk = NULL;
+	struct sctp_association *asoc;
+	struct sctp_transport *transport = NULL;
+	__u32 vtag = ntohl(sctphdr->vtag);
+
+	*app = NULL; *tpp = NULL;
+
+	af = sctp_get_af_specific(family);
+	if (unlikely(!af)) {
+		return NULL;
+	}
+
+	/* Initialize local addresses for lookups. */
+	af->from_skb(&saddr, skb, 1);
+	af->from_skb(&daddr, skb, 0);
+
+	/* Look for an association that matches the incoming ICMP error
+	 * packet.
+	 */
+	asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport);
+	if (!asoc)
+		return NULL;
+
+	sk = asoc->base.sk;
+
+	/* RFC 4960, Appendix C. ICMP Handling
+	 *
+	 * ICMP6) An implementation MUST validate that the Verification Tag
+	 * contained in the ICMP message matches the Verification Tag of
+	 * the peer.  If the Verification Tag is not 0 and does NOT
+	 * match, discard the ICMP message.  If it is 0 and the ICMP
+	 * message contains enough bytes to verify that the chunk type is
+	 * an INIT chunk and that the Initiate Tag matches the tag of the
+	 * peer, continue with ICMP7.  If the ICMP message is too short
+	 * or the chunk type or the Initiate Tag does not match, silently
+	 * discard the packet.
+	 */
+	if (vtag == 0) {
+		/* chunk header + first 4 octects of init header */
+		chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
+					      sizeof(struct sctphdr),
+					      sizeof(struct sctp_chunkhdr) +
+					      sizeof(__be32), &_chunkhdr);
+		if (!chunkhdr ||
+		    chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
+		    ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
+			goto out;
+
+	} else if (vtag != asoc->c.peer_vtag) {
+		goto out;
+	}
+
+	bh_lock_sock(sk);
+
+	/* If too many ICMPs get dropped on busy
+	 * servers this needs to be solved differently.
+	 */
+	if (sock_owned_by_user(sk))
+		__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
+
+	*app = asoc;
+	*tpp = transport;
+	return sk;
+
+out:
+	sctp_transport_put(transport);
+	return NULL;
+}
+
+/* Common cleanup code for icmp/icmpv6 error handler. */
+void sctp_err_finish(struct sock *sk, struct sctp_transport *t)
+	__releases(&((__sk)->sk_lock.slock))
+{
+	bh_unlock_sock(sk);
+	sctp_transport_put(t);
+}
+
+static void sctp_v4_err_handle(struct sctp_transport *t, struct sk_buff *skb,
+			       __u8 type, __u8 code, __u32 info)
+{
+	struct sctp_association *asoc = t->asoc;
+	struct sock *sk = asoc->base.sk;
+	int err = 0;
+
+	switch (type) {
+	case ICMP_PARAMETERPROB:
+		err = EPROTO;
+		break;
+	case ICMP_DEST_UNREACH:
+		if (code > NR_ICMP_UNREACH)
+			return;
+		if (code == ICMP_FRAG_NEEDED) {
+			sctp_icmp_frag_needed(sk, asoc, t, SCTP_TRUNC4(info));
+			return;
+		}
+		if (code == ICMP_PROT_UNREACH) {
+			sctp_icmp_proto_unreachable(sk, asoc, t);
+			return;
+		}
+		err = icmp_err_convert[code].errno;
+		break;
+	case ICMP_TIME_EXCEEDED:
+		if (code == ICMP_EXC_FRAGTIME)
+			return;
+
+		err = EHOSTUNREACH;
+		break;
+	case ICMP_REDIRECT:
+		sctp_icmp_redirect(sk, t, skb);
+		return;
+	default:
+		return;
+	}
+	if (!sock_owned_by_user(sk) && inet_sk(sk)->recverr) {
+		sk->sk_err = err;
+		sk_error_report(sk);
+	} else {  /* Only an error on timeout */
+		sk->sk_err_soft = err;
+	}
+}
+
+/*
+ * This routine is called by the ICMP module when it gets some
+ * sort of error condition.  If err < 0 then the socket should
+ * be closed and the error returned to the user.  If err > 0
+ * it's just the icmp type << 8 | icmp code.  After adjustment
+ * header points to the first 8 bytes of the sctp header.  We need
+ * to find the appropriate port.
+ *
+ * The locking strategy used here is very "optimistic". When
+ * someone else accesses the socket the ICMP is just dropped
+ * and for some paths there is no check at all.
+ * A more general error queue to queue errors for later handling
+ * is probably better.
+ *
+ */
+int sctp_v4_err(struct sk_buff *skb, __u32 info)
+{
+	const struct iphdr *iph = (const struct iphdr *)skb->data;
+	const int type = icmp_hdr(skb)->type;
+	const int code = icmp_hdr(skb)->code;
+	struct net *net = dev_net(skb->dev);
+	struct sctp_transport *transport;
+	struct sctp_association *asoc;
+	__u16 saveip, savesctp;
+	struct sock *sk;
+
+	/* Fix up skb to look at the embedded net header. */
+	saveip = skb->network_header;
+	savesctp = skb->transport_header;
+	skb_reset_network_header(skb);
+	skb_set_transport_header(skb, iph->ihl * 4);
+	sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
+	/* Put back, the original values. */
+	skb->network_header = saveip;
+	skb->transport_header = savesctp;
+	if (!sk) {
+		__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
+		return -ENOENT;
+	}
+
+	sctp_v4_err_handle(transport, skb, type, code, info);
+	sctp_err_finish(sk, transport);
+
+	return 0;
+}
+
+int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb)
+{
+	struct net *net = dev_net(skb->dev);
+	struct sctp_association *asoc;
+	struct sctp_transport *t;
+	struct icmphdr *hdr;
+	__u32 info = 0;
+
+	skb->transport_header += sizeof(struct udphdr);
+	sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &t);
+	if (!sk) {
+		__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
+		return -ENOENT;
+	}
+
+	skb->transport_header -= sizeof(struct udphdr);
+	hdr = (struct icmphdr *)(skb_network_header(skb) - sizeof(struct icmphdr));
+	if (hdr->type == ICMP_REDIRECT) {
+		/* can't be handled without outer iphdr known, leave it to udp_err */
+		sctp_err_finish(sk, t);
+		return 0;
+	}
+	if (hdr->type == ICMP_DEST_UNREACH && hdr->code == ICMP_FRAG_NEEDED)
+		info = ntohs(hdr->un.frag.mtu);
+	sctp_v4_err_handle(t, skb, hdr->type, hdr->code, info);
+
+	sctp_err_finish(sk, t);
+	return 1;
+}
+
+/*
+ * RFC 2960, 8.4 - Handle "Out of the blue" Packets.
+ *
+ * This function scans all the chunks in the OOTB packet to determine if
+ * the packet should be discarded right away.  If a response might be needed
+ * for this packet, or, if further processing is possible, the packet will
+ * be queued to a proper inqueue for the next phase of handling.
+ *
+ * Output:
+ * Return 0 - If further processing is needed.
+ * Return 1 - If the packet can be discarded right away.
+ */
+static int sctp_rcv_ootb(struct sk_buff *skb)
+{
+	struct sctp_chunkhdr *ch, _ch;
+	int ch_end, offset = 0;
+
+	/* Scan through all the chunks in the packet.  */
+	do {
+		/* Make sure we have at least the header there */
+		if (offset + sizeof(_ch) > skb->len)
+			break;
+
+		ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch);
+
+		/* Break out if chunk length is less then minimal. */
+		if (!ch || ntohs(ch->length) < sizeof(_ch))
+			break;
+
+		ch_end = offset + SCTP_PAD4(ntohs(ch->length));
+		if (ch_end > skb->len)
+			break;
+
+		/* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
+		 * receiver MUST silently discard the OOTB packet and take no
+		 * further action.
+		 */
+		if (SCTP_CID_ABORT == ch->type)
+			goto discard;
+
+		/* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
+		 * chunk, the receiver should silently discard the packet
+		 * and take no further action.
+		 */
+		if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
+			goto discard;
+
+		/* RFC 4460, 2.11.2
+		 * This will discard packets with INIT chunk bundled as
+		 * subsequent chunks in the packet.  When INIT is first,
+		 * the normal INIT processing will discard the chunk.
+		 */
+		if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
+			goto discard;
+
+		offset = ch_end;
+	} while (ch_end < skb->len);
+
+	return 0;
+
+discard:
+	return 1;
+}
+
+/* Insert endpoint into the hash table.  */
+static int __sctp_hash_endpoint(struct sctp_endpoint *ep)
+{
+	struct sock *sk = ep->base.sk;
+	struct net *net = sock_net(sk);
+	struct sctp_hashbucket *head;
+
+	ep->hashent = sctp_ep_hashfn(net, ep->base.bind_addr.port);
+	head = &sctp_ep_hashtable[ep->hashent];
+
+	if (sk->sk_reuseport) {
+		bool any = sctp_is_ep_boundall(sk);
+		struct sctp_endpoint *ep2;
+		struct list_head *list;
+		int cnt = 0, err = 1;
+
+		list_for_each(list, &ep->base.bind_addr.address_list)
+			cnt++;
+
+		sctp_for_each_hentry(ep2, &head->chain) {
+			struct sock *sk2 = ep2->base.sk;
+
+			if (!net_eq(sock_net(sk2), net) || sk2 == sk ||
+			    !uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) ||
+			    !sk2->sk_reuseport)
+				continue;
+
+			err = sctp_bind_addrs_check(sctp_sk(sk2),
+						    sctp_sk(sk), cnt);
+			if (!err) {
+				err = reuseport_add_sock(sk, sk2, any);
+				if (err)
+					return err;
+				break;
+			} else if (err < 0) {
+				return err;
+			}
+		}
+
+		if (err) {
+			err = reuseport_alloc(sk, any);
+			if (err)
+				return err;
+		}
+	}
+
+	write_lock(&head->lock);
+	hlist_add_head(&ep->node, &head->chain);
+	write_unlock(&head->lock);
+	return 0;
+}
+
+/* Add an endpoint to the hash. Local BH-safe. */
+int sctp_hash_endpoint(struct sctp_endpoint *ep)
+{
+	int err;
+
+	local_bh_disable();
+	err = __sctp_hash_endpoint(ep);
+	local_bh_enable();
+
+	return err;
+}
+
+/* Remove endpoint from the hash table.  */
+static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
+{
+	struct sock *sk = ep->base.sk;
+	struct sctp_hashbucket *head;
+
+	ep->hashent = sctp_ep_hashfn(sock_net(sk), ep->base.bind_addr.port);
+
+	head = &sctp_ep_hashtable[ep->hashent];
+
+	if (rcu_access_pointer(sk->sk_reuseport_cb))
+		reuseport_detach_sock(sk);
+
+	write_lock(&head->lock);
+	hlist_del_init(&ep->node);
+	write_unlock(&head->lock);
+}
+
+/* Remove endpoint from the hash.  Local BH-safe. */
+void sctp_unhash_endpoint(struct sctp_endpoint *ep)
+{
+	local_bh_disable();
+	__sctp_unhash_endpoint(ep);
+	local_bh_enable();
+}
+
+static inline __u32 sctp_hashfn(const struct net *net, __be16 lport,
+				const union sctp_addr *paddr, __u32 seed)
+{
+	__u32 addr;
+
+	if (paddr->sa.sa_family == AF_INET6)
+		addr = jhash(&paddr->v6.sin6_addr, 16, seed);
+	else
+		addr = (__force __u32)paddr->v4.sin_addr.s_addr;
+
+	return  jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
+			     (__force __u32)lport, net_hash_mix(net), seed);
+}
+
+/* Look up an endpoint. */
+static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
+					struct net *net, struct sk_buff *skb,
+					const union sctp_addr *laddr,
+					const union sctp_addr *paddr)
+{
+	struct sctp_hashbucket *head;
+	struct sctp_endpoint *ep;
+	struct sock *sk;
+	__be16 lport;
+	int hash;
+
+	lport = laddr->v4.sin_port;
+	hash = sctp_ep_hashfn(net, ntohs(lport));
+	head = &sctp_ep_hashtable[hash];
+	read_lock(&head->lock);
+	sctp_for_each_hentry(ep, &head->chain) {
+		if (sctp_endpoint_is_match(ep, net, laddr))
+			goto hit;
+	}
+
+	ep = sctp_sk(net->sctp.ctl_sock)->ep;
+
+hit:
+	sk = ep->base.sk;
+	if (sk->sk_reuseport) {
+		__u32 phash = sctp_hashfn(net, lport, paddr, 0);
+
+		sk = reuseport_select_sock(sk, phash, skb,
+					   sizeof(struct sctphdr));
+		if (sk)
+			ep = sctp_sk(sk)->ep;
+	}
+	sctp_endpoint_hold(ep);
+	read_unlock(&head->lock);
+	return ep;
+}
+
+/* rhashtable for transport */
+struct sctp_hash_cmp_arg {
+	const union sctp_addr	*paddr;
+	const struct net	*net;
+	__be16			lport;
+};
+
+static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
+				const void *ptr)
+{
+	struct sctp_transport *t = (struct sctp_transport *)ptr;
+	const struct sctp_hash_cmp_arg *x = arg->key;
+	int err = 1;
+
+	if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
+		return err;
+	if (!sctp_transport_hold(t))
+		return err;
+
+	if (!net_eq(t->asoc->base.net, x->net))
+		goto out;
+	if (x->lport != htons(t->asoc->base.bind_addr.port))
+		goto out;
+
+	err = 0;
+out:
+	sctp_transport_put(t);
+	return err;
+}
+
+static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
+{
+	const struct sctp_transport *t = data;
+
+	return sctp_hashfn(t->asoc->base.net,
+			   htons(t->asoc->base.bind_addr.port),
+			   &t->ipaddr, seed);
+}
+
+static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed)
+{
+	const struct sctp_hash_cmp_arg *x = data;
+
+	return sctp_hashfn(x->net, x->lport, x->paddr, seed);
+}
+
+static const struct rhashtable_params sctp_hash_params = {
+	.head_offset		= offsetof(struct sctp_transport, node),
+	.hashfn			= sctp_hash_key,
+	.obj_hashfn		= sctp_hash_obj,
+	.obj_cmpfn		= sctp_hash_cmp,
+	.automatic_shrinking	= true,
+};
+
+int sctp_transport_hashtable_init(void)
+{
+	return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params);
+}
+
+void sctp_transport_hashtable_destroy(void)
+{
+	rhltable_destroy(&sctp_transport_hashtable);
+}
+
+int sctp_hash_transport(struct sctp_transport *t)
+{
+	struct sctp_transport *transport;
+	struct rhlist_head *tmp, *list;
+	struct sctp_hash_cmp_arg arg;
+	int err;
+
+	if (t->asoc->temp)
+		return 0;
+
+	arg.net   = t->asoc->base.net;
+	arg.paddr = &t->ipaddr;
+	arg.lport = htons(t->asoc->base.bind_addr.port);
+
+	rcu_read_lock();
+	list = rhltable_lookup(&sctp_transport_hashtable, &arg,
+			       sctp_hash_params);
+
+	rhl_for_each_entry_rcu(transport, tmp, list, node)
+		if (transport->asoc->ep == t->asoc->ep) {
+			rcu_read_unlock();
+			return -EEXIST;
+		}
+	rcu_read_unlock();
+
+	err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
+				  &t->node, sctp_hash_params);
+	if (err)
+		pr_err_once("insert transport fail, errno %d\n", err);
+
+	return err;
+}
+
+void sctp_unhash_transport(struct sctp_transport *t)
+{
+	if (t->asoc->temp)
+		return;
+
+	rhltable_remove(&sctp_transport_hashtable, &t->node,
+			sctp_hash_params);
+}
+
+/* return a transport with holding it */
+struct sctp_transport *sctp_addrs_lookup_transport(
+				struct net *net,
+				const union sctp_addr *laddr,
+				const union sctp_addr *paddr)
+{
+	struct rhlist_head *tmp, *list;
+	struct sctp_transport *t;
+	struct sctp_hash_cmp_arg arg = {
+		.paddr = paddr,
+		.net   = net,
+		.lport = laddr->v4.sin_port,
+	};
+
+	list = rhltable_lookup(&sctp_transport_hashtable, &arg,
+			       sctp_hash_params);
+
+	rhl_for_each_entry_rcu(t, tmp, list, node) {
+		if (!sctp_transport_hold(t))
+			continue;
+
+		if (sctp_bind_addr_match(&t->asoc->base.bind_addr,
+					 laddr, sctp_sk(t->asoc->base.sk)))
+			return t;
+		sctp_transport_put(t);
+	}
+
+	return NULL;
+}
+
+/* return a transport without holding it, as it's only used under sock lock */
+struct sctp_transport *sctp_epaddr_lookup_transport(
+				const struct sctp_endpoint *ep,
+				const union sctp_addr *paddr)
+{
+	struct rhlist_head *tmp, *list;
+	struct sctp_transport *t;
+	struct sctp_hash_cmp_arg arg = {
+		.paddr = paddr,
+		.net   = ep->base.net,
+		.lport = htons(ep->base.bind_addr.port),
+	};
+
+	list = rhltable_lookup(&sctp_transport_hashtable, &arg,
+			       sctp_hash_params);
+
+	rhl_for_each_entry_rcu(t, tmp, list, node)
+		if (ep == t->asoc->ep)
+			return t;
+
+	return NULL;
+}
+
+/* Look up an association. */
+static struct sctp_association *__sctp_lookup_association(
+					struct net *net,
+					const union sctp_addr *local,
+					const union sctp_addr *peer,
+					struct sctp_transport **pt)
+{
+	struct sctp_transport *t;
+	struct sctp_association *asoc = NULL;
+
+	t = sctp_addrs_lookup_transport(net, local, peer);
+	if (!t)
+		goto out;
+
+	asoc = t->asoc;
+	*pt = t;
+
+out:
+	return asoc;
+}
+
+/* Look up an association. protected by RCU read lock */
+static
+struct sctp_association *sctp_lookup_association(struct net *net,
+						 const union sctp_addr *laddr,
+						 const union sctp_addr *paddr,
+						 struct sctp_transport **transportp)
+{
+	struct sctp_association *asoc;
+
+	rcu_read_lock();
+	asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
+	rcu_read_unlock();
+
+	return asoc;
+}
+
+/* Is there an association matching the given local and peer addresses? */
+bool sctp_has_association(struct net *net,
+			  const union sctp_addr *laddr,
+			  const union sctp_addr *paddr)
+{
+	struct sctp_transport *transport;
+
+	if (sctp_lookup_association(net, laddr, paddr, &transport)) {
+		sctp_transport_put(transport);
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * SCTP Implementors Guide, 2.18 Handling of address
+ * parameters within the INIT or INIT-ACK.
+ *
+ * D) When searching for a matching TCB upon reception of an INIT
+ *    or INIT-ACK chunk the receiver SHOULD use not only the
+ *    source address of the packet (containing the INIT or
+ *    INIT-ACK) but the receiver SHOULD also use all valid
+ *    address parameters contained within the chunk.
+ *
+ * 2.18.3 Solution description
+ *
+ * This new text clearly specifies to an implementor the need
+ * to look within the INIT or INIT-ACK. Any implementation that
+ * does not do this, may not be able to establish associations
+ * in certain circumstances.
+ *
+ */
+static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
+	struct sk_buff *skb,
+	const union sctp_addr *laddr, struct sctp_transport **transportp)
+{
+	struct sctp_association *asoc;
+	union sctp_addr addr;
+	union sctp_addr *paddr = &addr;
+	struct sctphdr *sh = sctp_hdr(skb);
+	union sctp_params params;
+	struct sctp_init_chunk *init;
+	struct sctp_af *af;
+
+	/*
+	 * This code will NOT touch anything inside the chunk--it is
+	 * strictly READ-ONLY.
+	 *
+	 * RFC 2960 3  SCTP packet Format
+	 *
+	 * Multiple chunks can be bundled into one SCTP packet up to
+	 * the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
+	 * COMPLETE chunks.  These chunks MUST NOT be bundled with any
+	 * other chunk in a packet.  See Section 6.10 for more details
+	 * on chunk bundling.
+	 */
+
+	/* Find the start of the TLVs and the end of the chunk.  This is
+	 * the region we search for address parameters.
+	 */
+	init = (struct sctp_init_chunk *)skb->data;
+
+	/* Walk the parameters looking for embedded addresses. */
+	sctp_walk_params(params, init, init_hdr.params) {
+
+		/* Note: Ignoring hostname addresses. */
+		af = sctp_get_af_specific(param_type2af(params.p->type));
+		if (!af)
+			continue;
+
+		if (!af->from_addr_param(paddr, params.addr, sh->source, 0))
+			continue;
+
+		asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
+		if (asoc)
+			return asoc;
+	}
+
+	return NULL;
+}
+
+/* ADD-IP, Section 5.2
+ * When an endpoint receives an ASCONF Chunk from the remote peer
+ * special procedures may be needed to identify the association the
+ * ASCONF Chunk is associated with. To properly find the association
+ * the following procedures SHOULD be followed:
+ *
+ * D2) If the association is not found, use the address found in the
+ * Address Parameter TLV combined with the port number found in the
+ * SCTP common header. If found proceed to rule D4.
+ *
+ * D2-ext) If more than one ASCONF Chunks are packed together, use the
+ * address found in the ASCONF Address Parameter TLV of each of the
+ * subsequent ASCONF Chunks. If found, proceed to rule D4.
+ */
+static struct sctp_association *__sctp_rcv_asconf_lookup(
+					struct net *net,
+					struct sctp_chunkhdr *ch,
+					const union sctp_addr *laddr,
+					__be16 peer_port,
+					struct sctp_transport **transportp)
+{
+	struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch;
+	struct sctp_af *af;
+	union sctp_addr_param *param;
+	union sctp_addr paddr;
+
+	if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr))
+		return NULL;
+
+	/* Skip over the ADDIP header and find the Address parameter */
+	param = (union sctp_addr_param *)(asconf + 1);
+
+	af = sctp_get_af_specific(param_type2af(param->p.type));
+	if (unlikely(!af))
+		return NULL;
+
+	if (!af->from_addr_param(&paddr, param, peer_port, 0))
+		return NULL;
+
+	return __sctp_lookup_association(net, laddr, &paddr, transportp);
+}
+
+
+/* SCTP-AUTH, Section 6.3:
+*    If the receiver does not find a STCB for a packet containing an AUTH
+*    chunk as the first chunk and not a COOKIE-ECHO chunk as the second
+*    chunk, it MUST use the chunks after the AUTH chunk to look up an existing
+*    association.
+*
+* This means that any chunks that can help us identify the association need
+* to be looked at to find this association.
+*/
+static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
+				      struct sk_buff *skb,
+				      const union sctp_addr *laddr,
+				      struct sctp_transport **transportp)
+{
+	struct sctp_association *asoc = NULL;
+	struct sctp_chunkhdr *ch;
+	int have_auth = 0;
+	unsigned int chunk_num = 1;
+	__u8 *ch_end;
+
+	/* Walk through the chunks looking for AUTH or ASCONF chunks
+	 * to help us find the association.
+	 */
+	ch = (struct sctp_chunkhdr *)skb->data;
+	do {
+		/* Break out if chunk length is less then minimal. */
+		if (ntohs(ch->length) < sizeof(*ch))
+			break;
+
+		ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
+		if (ch_end > skb_tail_pointer(skb))
+			break;
+
+		switch (ch->type) {
+		case SCTP_CID_AUTH:
+			have_auth = chunk_num;
+			break;
+
+		case SCTP_CID_COOKIE_ECHO:
+			/* If a packet arrives containing an AUTH chunk as
+			 * a first chunk, a COOKIE-ECHO chunk as the second
+			 * chunk, and possibly more chunks after them, and
+			 * the receiver does not have an STCB for that
+			 * packet, then authentication is based on
+			 * the contents of the COOKIE- ECHO chunk.
+			 */
+			if (have_auth == 1 && chunk_num == 2)
+				return NULL;
+			break;
+
+		case SCTP_CID_ASCONF:
+			if (have_auth || net->sctp.addip_noauth)
+				asoc = __sctp_rcv_asconf_lookup(
+						net, ch, laddr,
+						sctp_hdr(skb)->source,
+						transportp);
+			break;
+		default:
+			break;
+		}
+
+		if (asoc)
+			break;
+
+		ch = (struct sctp_chunkhdr *)ch_end;
+		chunk_num++;
+	} while (ch_end + sizeof(*ch) < skb_tail_pointer(skb));
+
+	return asoc;
+}
+
+/*
+ * There are circumstances when we need to look inside the SCTP packet
+ * for information to help us find the association.   Examples
+ * include looking inside of INIT/INIT-ACK chunks or after the AUTH
+ * chunks.
+ */
+static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
+				      struct sk_buff *skb,
+				      const union sctp_addr *laddr,
+				      struct sctp_transport **transportp)
+{
+	struct sctp_chunkhdr *ch;
+
+	/* We do not allow GSO frames here as we need to linearize and
+	 * then cannot guarantee frame boundaries. This shouldn't be an
+	 * issue as packets hitting this are mostly INIT or INIT-ACK and
+	 * those cannot be on GSO-style anyway.
+	 */
+	if (skb_is_gso(skb) && skb_is_gso_sctp(skb))
+		return NULL;
+
+	ch = (struct sctp_chunkhdr *)skb->data;
+
+	/* The code below will attempt to walk the chunk and extract
+	 * parameter information.  Before we do that, we need to verify
+	 * that the chunk length doesn't cause overflow.  Otherwise, we'll
+	 * walk off the end.
+	 */
+	if (SCTP_PAD4(ntohs(ch->length)) > skb->len)
+		return NULL;
+
+	/* If this is INIT/INIT-ACK look inside the chunk too. */
+	if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
+		return __sctp_rcv_init_lookup(net, skb, laddr, transportp);
+
+	return __sctp_rcv_walk_lookup(net, skb, laddr, transportp);
+}
+
+/* Lookup an association for an inbound skb. */
+static struct sctp_association *__sctp_rcv_lookup(struct net *net,
+				      struct sk_buff *skb,
+				      const union sctp_addr *paddr,
+				      const union sctp_addr *laddr,
+				      struct sctp_transport **transportp)
+{
+	struct sctp_association *asoc;
+
+	asoc = __sctp_lookup_association(net, laddr, paddr, transportp);
+	if (asoc)
+		goto out;
+
+	/* Further lookup for INIT/INIT-ACK packets.
+	 * SCTP Implementors Guide, 2.18 Handling of address
+	 * parameters within the INIT or INIT-ACK.
+	 */
+	asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp);
+	if (asoc)
+		goto out;
+
+	if (paddr->sa.sa_family == AF_INET)
+		pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n",
+			 &laddr->v4.sin_addr, ntohs(laddr->v4.sin_port),
+			 &paddr->v4.sin_addr, ntohs(paddr->v4.sin_port));
+	else
+		pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n",
+			 &laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port),
+			 &paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port));
+
+out:
+	return asoc;
+}