Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 1162 insertions, 0 deletions

diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
new file mode 100644
index 000000000..991ca2dc2
--- /dev/null
+++ b/net/dccp/ipv6.c
@@ -0,0 +1,1162 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	DCCP over IPv6
+ *	Linux INET6 implementation
+ *
+ *	Based on net/dccp6/ipv6.c
+ *
+ *	Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
+ */
+
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/xfrm.h>
+#include <linux/string.h>
+
+#include <net/addrconf.h>
+#include <net/inet_common.h>
+#include <net/inet_hashtables.h>
+#include <net/inet_sock.h>
+#include <net/inet6_connection_sock.h>
+#include <net/inet6_hashtables.h>
+#include <net/ip6_route.h>
+#include <net/ipv6.h>
+#include <net/protocol.h>
+#include <net/transp_v6.h>
+#include <net/ip6_checksum.h>
+#include <net/xfrm.h>
+#include <net/secure_seq.h>
+#include <net/sock.h>
+
+#include "dccp.h"
+#include "ipv6.h"
+#include "feat.h"
+
+/* The per-net dccp.v6_ctl_sk is used for sending RSTs and ACKs */
+
+static const struct inet_connection_sock_af_ops dccp_ipv6_mapped;
+static const struct inet_connection_sock_af_ops dccp_ipv6_af_ops;
+
+/* add pseudo-header to DCCP checksum stored in skb->csum */
+static inline __sum16 dccp_v6_csum_finish(struct sk_buff *skb,
+				      const struct in6_addr *saddr,
+				      const struct in6_addr *daddr)
+{
+	return csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_DCCP, skb->csum);
+}
+
+static inline void dccp_v6_send_check(struct sock *sk, struct sk_buff *skb)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct dccp_hdr *dh = dccp_hdr(skb);
+
+	dccp_csum_outgoing(skb);
+	dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &sk->sk_v6_daddr);
+}
+
+static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb)
+{
+	return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
+					     ipv6_hdr(skb)->saddr.s6_addr32,
+					     dccp_hdr(skb)->dccph_dport,
+					     dccp_hdr(skb)->dccph_sport     );
+
+}
+
+static int dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+			u8 type, u8 code, int offset, __be32 info)
+{
+	const struct ipv6hdr *hdr;
+	const struct dccp_hdr *dh;
+	struct dccp_sock *dp;
+	struct ipv6_pinfo *np;
+	struct sock *sk;
+	int err;
+	__u64 seq;
+	struct net *net = dev_net(skb->dev);
+
+	if (!pskb_may_pull(skb, offset + sizeof(*dh)))
+		return -EINVAL;
+	dh = (struct dccp_hdr *)(skb->data + offset);
+	if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
+		return -EINVAL;
+	hdr = (const struct ipv6hdr *)skb->data;
+	dh = (struct dccp_hdr *)(skb->data + offset);
+
+	sk = __inet6_lookup_established(net, &dccp_hashinfo,
+					&hdr->daddr, dh->dccph_dport,
+					&hdr->saddr, ntohs(dh->dccph_sport),
+					inet6_iif(skb), 0);
+
+	if (!sk) {
+		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
+				  ICMP6_MIB_INERRORS);
+		return -ENOENT;
+	}
+
+	if (sk->sk_state == DCCP_TIME_WAIT) {
+		inet_twsk_put(inet_twsk(sk));
+		return 0;
+	}
+	seq = dccp_hdr_seq(dh);
+	if (sk->sk_state == DCCP_NEW_SYN_RECV) {
+		dccp_req_err(sk, seq);
+		return 0;
+	}
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk))
+		__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
+
+	if (sk->sk_state == DCCP_CLOSED)
+		goto out;
+
+	dp = dccp_sk(sk);
+	if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
+	    !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
+		__NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
+		goto out;
+	}
+
+	np = inet6_sk(sk);
+
+	if (type == NDISC_REDIRECT) {
+		if (!sock_owned_by_user(sk)) {
+			struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);
+
+			if (dst)
+				dst->ops->redirect(dst, sk, skb);
+		}
+		goto out;
+	}
+
+	if (type == ICMPV6_PKT_TOOBIG) {
+		struct dst_entry *dst = NULL;
+
+		if (!ip6_sk_accept_pmtu(sk))
+			goto out;
+
+		if (sock_owned_by_user(sk))
+			goto out;
+		if ((1 << sk->sk_state) & (DCCPF_LISTEN | DCCPF_CLOSED))
+			goto out;
+
+		dst = inet6_csk_update_pmtu(sk, ntohl(info));
+		if (!dst)
+			goto out;
+
+		if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst))
+			dccp_sync_mss(sk, dst_mtu(dst));
+		goto out;
+	}
+
+	icmpv6_err_convert(type, code, &err);
+
+	/* Might be for an request_sock */
+	switch (sk->sk_state) {
+	case DCCP_REQUESTING:
+	case DCCP_RESPOND:  /* Cannot happen.
+			       It can, it SYNs are crossed. --ANK */
+		if (!sock_owned_by_user(sk)) {
+			__DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
+			sk->sk_err = err;
+			/*
+			 * Wake people up to see the error
+			 * (see connect in sock.c)
+			 */
+			sk->sk_error_report(sk);
+			dccp_done(sk);
+		} else
+			sk->sk_err_soft = err;
+		goto out;
+	}
+
+	if (!sock_owned_by_user(sk) && np->recverr) {
+		sk->sk_err = err;
+		sk->sk_error_report(sk);
+	} else
+		sk->sk_err_soft = err;
+
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+	return 0;
+}
+
+
+static int dccp_v6_send_response(const struct sock *sk, struct request_sock *req)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct sk_buff *skb;
+	struct in6_addr *final_p, final;
+	struct flowi6 fl6;
+	int err = -1;
+	struct dst_entry *dst;
+
+	memset(&fl6, 0, sizeof(fl6));
+	fl6.flowi6_proto = IPPROTO_DCCP;
+	fl6.daddr = ireq->ir_v6_rmt_addr;
+	fl6.saddr = ireq->ir_v6_loc_addr;
+	fl6.flowlabel = 0;
+	fl6.flowi6_oif = ireq->ir_iif;
+	fl6.fl6_dport = ireq->ir_rmt_port;
+	fl6.fl6_sport = htons(ireq->ir_num);
+	security_req_classify_flow(req, flowi6_to_flowi_common(&fl6));
+
+
+	rcu_read_lock();
+	final_p = fl6_update_dst(&fl6, rcu_dereference(np->opt), &final);
+	rcu_read_unlock();
+
+	dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		dst = NULL;
+		goto done;
+	}
+
+	skb = dccp_make_response(sk, dst, req);
+	if (skb != NULL) {
+		struct dccp_hdr *dh = dccp_hdr(skb);
+		struct ipv6_txoptions *opt;
+
+		dh->dccph_checksum = dccp_v6_csum_finish(skb,
+							 &ireq->ir_v6_loc_addr,
+							 &ireq->ir_v6_rmt_addr);
+		fl6.daddr = ireq->ir_v6_rmt_addr;
+		rcu_read_lock();
+		opt = ireq->ipv6_opt;
+		if (!opt)
+			opt = rcu_dereference(np->opt);
+		err = ip6_xmit(sk, skb, &fl6, sk->sk_mark, opt, np->tclass,
+			       sk->sk_priority);
+		rcu_read_unlock();
+		err = net_xmit_eval(err);
+	}
+
+done:
+	dst_release(dst);
+	return err;
+}
+
+static void dccp_v6_reqsk_destructor(struct request_sock *req)
+{
+	dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
+	kfree(inet_rsk(req)->ipv6_opt);
+	kfree_skb(inet_rsk(req)->pktopts);
+}
+
+static void dccp_v6_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
+{
+	const struct ipv6hdr *rxip6h;
+	struct sk_buff *skb;
+	struct flowi6 fl6;
+	struct net *net = dev_net(skb_dst(rxskb)->dev);
+	struct sock *ctl_sk = net->dccp.v6_ctl_sk;
+	struct dst_entry *dst;
+
+	if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
+		return;
+
+	if (!ipv6_unicast_destination(rxskb))
+		return;
+
+	skb = dccp_ctl_make_reset(ctl_sk, rxskb);
+	if (skb == NULL)
+		return;
+
+	rxip6h = ipv6_hdr(rxskb);
+	dccp_hdr(skb)->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,
+							    &rxip6h->daddr);
+
+	memset(&fl6, 0, sizeof(fl6));
+	fl6.daddr = rxip6h->saddr;
+	fl6.saddr = rxip6h->daddr;
+
+	fl6.flowi6_proto = IPPROTO_DCCP;
+	fl6.flowi6_oif = inet6_iif(rxskb);
+	fl6.fl6_dport = dccp_hdr(skb)->dccph_dport;
+	fl6.fl6_sport = dccp_hdr(skb)->dccph_sport;
+	security_skb_classify_flow(rxskb, flowi6_to_flowi_common(&fl6));
+
+	/* sk = NULL, but it is safe for now. RST socket required. */
+	dst = ip6_dst_lookup_flow(sock_net(ctl_sk), ctl_sk, &fl6, NULL);
+	if (!IS_ERR(dst)) {
+		skb_dst_set(skb, dst);
+		ip6_xmit(ctl_sk, skb, &fl6, 0, NULL, 0, 0);
+		DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
+		DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
+		return;
+	}
+
+	kfree_skb(skb);
+}
+
+static struct request_sock_ops dccp6_request_sock_ops = {
+	.family		= AF_INET6,
+	.obj_size	= sizeof(struct dccp6_request_sock),
+	.rtx_syn_ack	= dccp_v6_send_response,
+	.send_ack	= dccp_reqsk_send_ack,
+	.destructor	= dccp_v6_reqsk_destructor,
+	.send_reset	= dccp_v6_ctl_send_reset,
+	.syn_ack_timeout = dccp_syn_ack_timeout,
+};
+
+static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+	struct request_sock *req;
+	struct dccp_request_sock *dreq;
+	struct inet_request_sock *ireq;
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
+	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+
+	if (skb->protocol == htons(ETH_P_IP))
+		return dccp_v4_conn_request(sk, skb);
+
+	if (!ipv6_unicast_destination(skb))
+		return 0;	/* discard, don't send a reset here */
+
+	if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
+		__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
+		return 0;
+	}
+
+	if (dccp_bad_service_code(sk, service)) {
+		dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
+		goto drop;
+	}
+	/*
+	 * There are no SYN attacks on IPv6, yet...
+	 */
+	dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
+	if (inet_csk_reqsk_queue_is_full(sk))
+		goto drop;
+
+	if (sk_acceptq_is_full(sk))
+		goto drop;
+
+	req = inet_reqsk_alloc(&dccp6_request_sock_ops, sk, true);
+	if (req == NULL)
+		goto drop;
+
+	if (dccp_reqsk_init(req, dccp_sk(sk), skb))
+		goto drop_and_free;
+
+	dreq = dccp_rsk(req);
+	if (dccp_parse_options(sk, dreq, skb))
+		goto drop_and_free;
+
+	ireq = inet_rsk(req);
+	ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
+	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
+	ireq->ireq_family = AF_INET6;
+	ireq->ir_mark = inet_request_mark(sk, skb);
+
+	if (security_inet_conn_request(sk, skb, req))
+		goto drop_and_free;
+
+	if (ipv6_opt_accepted(sk, skb, IP6CB(skb)) ||
+	    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
+	    np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
+		refcount_inc(&skb->users);
+		ireq->pktopts = skb;
+	}
+	ireq->ir_iif = sk->sk_bound_dev_if;
+
+	/* So that link locals have meaning */
+	if (!sk->sk_bound_dev_if &&
+	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
+		ireq->ir_iif = inet6_iif(skb);
+
+	/*
+	 * Step 3: Process LISTEN state
+	 *
+	 *   Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
+	 *
+	 * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
+	 */
+	dreq->dreq_isr	   = dcb->dccpd_seq;
+	dreq->dreq_gsr     = dreq->dreq_isr;
+	dreq->dreq_iss	   = dccp_v6_init_sequence(skb);
+	dreq->dreq_gss     = dreq->dreq_iss;
+	dreq->dreq_service = service;
+
+	if (dccp_v6_send_response(sk, req))
+		goto drop_and_free;
+
+	inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
+	reqsk_put(req);
+	return 0;
+
+drop_and_free:
+	reqsk_free(req);
+drop:
+	__DCCP_INC_STATS(DCCP_MIB_ATTEMPTFAILS);
+	return -1;
+}
+
+static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
+					      struct sk_buff *skb,
+					      struct request_sock *req,
+					      struct dst_entry *dst,
+					      struct request_sock *req_unhash,
+					      bool *own_req)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+	struct ipv6_pinfo *newnp;
+	const struct ipv6_pinfo *np = inet6_sk(sk);
+	struct ipv6_txoptions *opt;
+	struct inet_sock *newinet;
+	struct dccp6_sock *newdp6;
+	struct sock *newsk;
+
+	if (skb->protocol == htons(ETH_P_IP)) {
+		/*
+		 *	v6 mapped
+		 */
+		newsk = dccp_v4_request_recv_sock(sk, skb, req, dst,
+						  req_unhash, own_req);
+		if (newsk == NULL)
+			return NULL;
+
+		newdp6 = (struct dccp6_sock *)newsk;
+		newinet = inet_sk(newsk);
+		newinet->pinet6 = &newdp6->inet6;
+		newnp = inet6_sk(newsk);
+
+		memcpy(newnp, np, sizeof(struct ipv6_pinfo));
+
+		newnp->saddr = newsk->sk_v6_rcv_saddr;
+
+		inet_csk(newsk)->icsk_af_ops = &dccp_ipv6_mapped;
+		newsk->sk_backlog_rcv = dccp_v4_do_rcv;
+		newnp->pktoptions  = NULL;
+		newnp->opt	   = NULL;
+		newnp->ipv6_mc_list = NULL;
+		newnp->ipv6_ac_list = NULL;
+		newnp->ipv6_fl_list = NULL;
+		newnp->mcast_oif   = inet_iif(skb);
+		newnp->mcast_hops  = ip_hdr(skb)->ttl;
+
+		/*
+		 * No need to charge this sock to the relevant IPv6 refcnt debug socks count
+		 * here, dccp_create_openreq_child now does this for us, see the comment in
+		 * that function for the gory details. -acme
+		 */
+
+		/* It is tricky place. Until this moment IPv4 tcp
+		   worked with IPv6 icsk.icsk_af_ops.
+		   Sync it now.
+		 */
+		dccp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);
+
+		return newsk;
+	}
+
+
+	if (sk_acceptq_is_full(sk))
+		goto out_overflow;
+
+	if (!dst) {
+		struct flowi6 fl6;
+
+		dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_DCCP);
+		if (!dst)
+			goto out;
+	}
+
+	newsk = dccp_create_openreq_child(sk, req, skb);
+	if (newsk == NULL)
+		goto out_nonewsk;
+
+	/*
+	 * No need to charge this sock to the relevant IPv6 refcnt debug socks
+	 * count here, dccp_create_openreq_child now does this for us, see the
+	 * comment in that function for the gory details. -acme
+	 */
+
+	ip6_dst_store(newsk, dst, NULL, NULL);
+	newsk->sk_route_caps = dst->dev->features & ~(NETIF_F_IP_CSUM |
+						      NETIF_F_TSO);
+	newdp6 = (struct dccp6_sock *)newsk;
+	newinet = inet_sk(newsk);
+	newinet->pinet6 = &newdp6->inet6;
+	newnp = inet6_sk(newsk);
+
+	memcpy(newnp, np, sizeof(struct ipv6_pinfo));
+
+	newsk->sk_v6_daddr	= ireq->ir_v6_rmt_addr;
+	newnp->saddr		= ireq->ir_v6_loc_addr;
+	newsk->sk_v6_rcv_saddr	= ireq->ir_v6_loc_addr;
+	newsk->sk_bound_dev_if	= ireq->ir_iif;
+
+	/* Now IPv6 options...
+
+	   First: no IPv4 options.
+	 */
+	newinet->inet_opt = NULL;
+
+	/* Clone RX bits */
+	newnp->rxopt.all = np->rxopt.all;
+
+	newnp->ipv6_mc_list = NULL;
+	newnp->ipv6_ac_list = NULL;
+	newnp->ipv6_fl_list = NULL;
+	newnp->pktoptions = NULL;
+	newnp->opt	  = NULL;
+	newnp->mcast_oif  = inet6_iif(skb);
+	newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
+
+	/*
+	 * Clone native IPv6 options from listening socket (if any)
+	 *
+	 * Yes, keeping reference count would be much more clever, but we make
+	 * one more one thing there: reattach optmem to newsk.
+	 */
+	opt = ireq->ipv6_opt;
+	if (!opt)
+		opt = rcu_dereference(np->opt);
+	if (opt) {
+		opt = ipv6_dup_options(newsk, opt);
+		RCU_INIT_POINTER(newnp->opt, opt);
+	}
+	inet_csk(newsk)->icsk_ext_hdr_len = 0;
+	if (opt)
+		inet_csk(newsk)->icsk_ext_hdr_len = opt->opt_nflen +
+						    opt->opt_flen;
+
+	dccp_sync_mss(newsk, dst_mtu(dst));
+
+	newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
+	newinet->inet_rcv_saddr = LOOPBACK4_IPV6;
+
+	if (__inet_inherit_port(sk, newsk) < 0) {
+		inet_csk_prepare_forced_close(newsk);
+		dccp_done(newsk);
+		goto out;
+	}
+	*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash), NULL);
+	/* Clone pktoptions received with SYN, if we own the req */
+	if (*own_req && ireq->pktopts) {
+		newnp->pktoptions = skb_clone_and_charge_r(ireq->pktopts, newsk);
+		consume_skb(ireq->pktopts);
+		ireq->pktopts = NULL;
+	}
+
+	return newsk;
+
+out_overflow:
+	__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+out_nonewsk:
+	dst_release(dst);
+out:
+	__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
+	return NULL;
+}
+
+/* The socket must have it's spinlock held when we get
+ * here.
+ *
+ * We have a potential double-lock case here, so even when
+ * doing backlog processing we use the BH locking scheme.
+ * This is because we cannot sleep with the original spinlock
+ * held.
+ */
+static int dccp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct sk_buff *opt_skb = NULL;
+
+	/* Imagine: socket is IPv6. IPv4 packet arrives,
+	   goes to IPv4 receive handler and backlogged.
+	   From backlog it always goes here. Kerboom...
+	   Fortunately, dccp_rcv_established and rcv_established
+	   handle them correctly, but it is not case with
+	   dccp_v6_hnd_req and dccp_v6_ctl_send_reset().   --ANK
+	 */
+
+	if (skb->protocol == htons(ETH_P_IP))
+		return dccp_v4_do_rcv(sk, skb);
+
+	if (sk_filter(sk, skb))
+		goto discard;
+
+	/*
+	 * socket locking is here for SMP purposes as backlog rcv is currently
+	 * called with bh processing disabled.
+	 */
+
+	/* Do Stevens' IPV6_PKTOPTIONS.
+
+	   Yes, guys, it is the only place in our code, where we
+	   may make it not affecting IPv4.
+	   The rest of code is protocol independent,
+	   and I do not like idea to uglify IPv4.
+
+	   Actually, all the idea behind IPV6_PKTOPTIONS
+	   looks not very well thought. For now we latch
+	   options, received in the last packet, enqueued
+	   by tcp. Feel free to propose better solution.
+					       --ANK (980728)
+	 */
+	if (np->rxopt.all)
+		opt_skb = skb_clone_and_charge_r(skb, sk);
+
+	if (sk->sk_state == DCCP_OPEN) { /* Fast path */
+		if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
+			goto reset;
+		if (opt_skb)
+			goto ipv6_pktoptions;
+		return 0;
+	}
+
+	/*
+	 *  Step 3: Process LISTEN state
+	 *     If S.state == LISTEN,
+	 *	 If P.type == Request or P contains a valid Init Cookie option,
+	 *	      (* Must scan the packet's options to check for Init
+	 *		 Cookies.  Only Init Cookies are processed here,
+	 *		 however; other options are processed in Step 8.  This
+	 *		 scan need only be performed if the endpoint uses Init
+	 *		 Cookies *)
+	 *	      (* Generate a new socket and switch to that socket *)
+	 *	      Set S := new socket for this port pair
+	 *	      S.state = RESPOND
+	 *	      Choose S.ISS (initial seqno) or set from Init Cookies
+	 *	      Initialize S.GAR := S.ISS
+	 *	      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
+	 *	      Continue with S.state == RESPOND
+	 *	      (* A Response packet will be generated in Step 11 *)
+	 *	 Otherwise,
+	 *	      Generate Reset(No Connection) unless P.type == Reset
+	 *	      Drop packet and return
+	 *
+	 * NOTE: the check for the packet types is done in
+	 *	 dccp_rcv_state_process
+	 */
+
+	if (dccp_rcv_state_process(sk, skb, dccp_hdr(skb), skb->len))
+		goto reset;
+	if (opt_skb)
+		goto ipv6_pktoptions;
+	return 0;
+
+reset:
+	dccp_v6_ctl_send_reset(sk, skb);
+discard:
+	if (opt_skb != NULL)
+		__kfree_skb(opt_skb);
+	kfree_skb(skb);
+	return 0;
+
+/* Handling IPV6_PKTOPTIONS skb the similar
+ * way it's done for net/ipv6/tcp_ipv6.c
+ */
+ipv6_pktoptions:
+	if (!((1 << sk->sk_state) & (DCCPF_CLOSED | DCCPF_LISTEN))) {
+		if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo)
+			np->mcast_oif = inet6_iif(opt_skb);
+		if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)
+			np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit;
+		if (np->rxopt.bits.rxflow || np->rxopt.bits.rxtclass)
+			np->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(opt_skb));
+		if (np->repflow)
+			np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb));
+		if (ipv6_opt_accepted(sk, opt_skb,
+				      &DCCP_SKB_CB(opt_skb)->header.h6)) {
+			memmove(IP6CB(opt_skb),
+				&DCCP_SKB_CB(opt_skb)->header.h6,
+				sizeof(struct inet6_skb_parm));
+			opt_skb = xchg(&np->pktoptions, opt_skb);
+		} else {
+			__kfree_skb(opt_skb);
+			opt_skb = xchg(&np->pktoptions, NULL);
+		}
+	}
+
+	kfree_skb(opt_skb);
+	return 0;
+}
+
+static int dccp_v6_rcv(struct sk_buff *skb)
+{
+	const struct dccp_hdr *dh;
+	bool refcounted;
+	struct sock *sk;
+	int min_cov;
+
+	/* Step 1: Check header basics */
+
+	if (dccp_invalid_packet(skb))
+		goto discard_it;
+
+	/* Step 1: If header checksum is incorrect, drop packet and return. */
+	if (dccp_v6_csum_finish(skb, &ipv6_hdr(skb)->saddr,
+				     &ipv6_hdr(skb)->daddr)) {
+		DCCP_WARN("dropped packet with invalid checksum\n");
+		goto discard_it;
+	}
+
+	dh = dccp_hdr(skb);
+
+	DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
+	DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;
+
+	if (dccp_packet_without_ack(skb))
+		DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
+	else
+		DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);
+
+lookup:
+	sk = __inet6_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
+			        dh->dccph_sport, dh->dccph_dport,
+				inet6_iif(skb), 0, &refcounted);
+	if (!sk) {
+		dccp_pr_debug("failed to look up flow ID in table and "
+			      "get corresponding socket\n");
+		goto no_dccp_socket;
+	}
+
+	/*
+	 * Step 2:
+	 *	... or S.state == TIMEWAIT,
+	 *		Generate Reset(No Connection) unless P.type == Reset
+	 *		Drop packet and return
+	 */
+	if (sk->sk_state == DCCP_TIME_WAIT) {
+		dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
+		inet_twsk_put(inet_twsk(sk));
+		goto no_dccp_socket;
+	}
+
+	if (sk->sk_state == DCCP_NEW_SYN_RECV) {
+		struct request_sock *req = inet_reqsk(sk);
+		struct sock *nsk;
+
+		sk = req->rsk_listener;
+		if (unlikely(sk->sk_state != DCCP_LISTEN)) {
+			inet_csk_reqsk_queue_drop_and_put(sk, req);
+			goto lookup;
+		}
+		sock_hold(sk);
+		refcounted = true;
+		nsk = dccp_check_req(sk, skb, req);
+		if (!nsk) {
+			reqsk_put(req);
+			goto discard_and_relse;
+		}
+		if (nsk == sk) {
+			reqsk_put(req);
+		} else if (dccp_child_process(sk, nsk, skb)) {
+			dccp_v6_ctl_send_reset(sk, skb);
+			goto discard_and_relse;
+		} else {
+			sock_put(sk);
+			return 0;
+		}
+	}
+	/*
+	 * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
+	 *	o if MinCsCov = 0, only packets with CsCov = 0 are accepted
+	 *	o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
+	 */
+	min_cov = dccp_sk(sk)->dccps_pcrlen;
+	if (dh->dccph_cscov  &&  (min_cov == 0 || dh->dccph_cscov < min_cov))  {
+		dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
+			      dh->dccph_cscov, min_cov);
+		/* FIXME: send Data Dropped option (see also dccp_v4_rcv) */
+		goto discard_and_relse;
+	}
+
+	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
+		goto discard_and_relse;
+
+	return __sk_receive_skb(sk, skb, 1, dh->dccph_doff * 4,
+				refcounted) ? -1 : 0;
+
+no_dccp_socket:
+	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
+		goto discard_it;
+	/*
+	 * Step 2:
+	 *	If no socket ...
+	 *		Generate Reset(No Connection) unless P.type == Reset
+	 *		Drop packet and return
+	 */
+	if (dh->dccph_type != DCCP_PKT_RESET) {
+		DCCP_SKB_CB(skb)->dccpd_reset_code =
+					DCCP_RESET_CODE_NO_CONNECTION;
+		dccp_v6_ctl_send_reset(sk, skb);
+	}
+
+discard_it:
+	kfree_skb(skb);
+	return 0;
+
+discard_and_relse:
+	if (refcounted)
+		sock_put(sk);
+	goto discard_it;
+}
+
+static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
+			   int addr_len)
+{
+	struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct inet_sock *inet = inet_sk(sk);
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct in6_addr *saddr = NULL, *final_p, final;
+	struct ipv6_txoptions *opt;
+	struct flowi6 fl6;
+	struct dst_entry *dst;
+	int addr_type;
+	int err;
+
+	dp->dccps_role = DCCP_ROLE_CLIENT;
+
+	if (addr_len < SIN6_LEN_RFC2133)
+		return -EINVAL;
+
+	if (usin->sin6_family != AF_INET6)
+		return -EAFNOSUPPORT;
+
+	memset(&fl6, 0, sizeof(fl6));
+
+	if (np->sndflow) {
+		fl6.flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;
+		IP6_ECN_flow_init(fl6.flowlabel);
+		if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
+			struct ip6_flowlabel *flowlabel;
+			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
+			if (IS_ERR(flowlabel))
+				return -EINVAL;
+			fl6_sock_release(flowlabel);
+		}
+	}
+	/*
+	 * connect() to INADDR_ANY means loopback (BSD'ism).
+	 */
+	if (ipv6_addr_any(&usin->sin6_addr))
+		usin->sin6_addr.s6_addr[15] = 1;
+
+	addr_type = ipv6_addr_type(&usin->sin6_addr);
+
+	if (addr_type & IPV6_ADDR_MULTICAST)
+		return -ENETUNREACH;
+
+	if (addr_type & IPV6_ADDR_LINKLOCAL) {
+		if (addr_len >= sizeof(struct sockaddr_in6) &&
+		    usin->sin6_scope_id) {
+			/* If interface is set while binding, indices
+			 * must coincide.
+			 */
+			if (sk->sk_bound_dev_if &&
+			    sk->sk_bound_dev_if != usin->sin6_scope_id)
+				return -EINVAL;
+
+			sk->sk_bound_dev_if = usin->sin6_scope_id;
+		}
+
+		/* Connect to link-local address requires an interface */
+		if (!sk->sk_bound_dev_if)
+			return -EINVAL;
+	}
+
+	sk->sk_v6_daddr = usin->sin6_addr;
+	np->flow_label = fl6.flowlabel;
+
+	/*
+	 * DCCP over IPv4
+	 */
+	if (addr_type == IPV6_ADDR_MAPPED) {
+		u32 exthdrlen = icsk->icsk_ext_hdr_len;
+		struct sockaddr_in sin;
+
+		SOCK_DEBUG(sk, "connect: ipv4 mapped\n");
+
+		if (__ipv6_only_sock(sk))
+			return -ENETUNREACH;
+
+		sin.sin_family = AF_INET;
+		sin.sin_port = usin->sin6_port;
+		sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];
+
+		icsk->icsk_af_ops = &dccp_ipv6_mapped;
+		sk->sk_backlog_rcv = dccp_v4_do_rcv;
+
+		err = dccp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
+		if (err) {
+			icsk->icsk_ext_hdr_len = exthdrlen;
+			icsk->icsk_af_ops = &dccp_ipv6_af_ops;
+			sk->sk_backlog_rcv = dccp_v6_do_rcv;
+			goto failure;
+		}
+		np->saddr = sk->sk_v6_rcv_saddr;
+		return err;
+	}
+
+	if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr))
+		saddr = &sk->sk_v6_rcv_saddr;
+
+	fl6.flowi6_proto = IPPROTO_DCCP;
+	fl6.daddr = sk->sk_v6_daddr;
+	fl6.saddr = saddr ? *saddr : np->saddr;
+	fl6.flowi6_oif = sk->sk_bound_dev_if;
+	fl6.fl6_dport = usin->sin6_port;
+	fl6.fl6_sport = inet->inet_sport;
+	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
+
+	opt = rcu_dereference_protected(np->opt, lockdep_sock_is_held(sk));
+	final_p = fl6_update_dst(&fl6, opt, &final);
+
+	dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		goto failure;
+	}
+
+	if (saddr == NULL) {
+		saddr = &fl6.saddr;
+		sk->sk_v6_rcv_saddr = *saddr;
+	}
+
+	/* set the source address */
+	np->saddr = *saddr;
+	inet->inet_rcv_saddr = LOOPBACK4_IPV6;
+
+	ip6_dst_store(sk, dst, NULL, NULL);
+
+	icsk->icsk_ext_hdr_len = 0;
+	if (opt)
+		icsk->icsk_ext_hdr_len = opt->opt_flen + opt->opt_nflen;
+
+	inet->inet_dport = usin->sin6_port;
+
+	dccp_set_state(sk, DCCP_REQUESTING);
+	err = inet6_hash_connect(&dccp_death_row, sk);
+	if (err)
+		goto late_failure;
+
+	dp->dccps_iss = secure_dccpv6_sequence_number(np->saddr.s6_addr32,
+						      sk->sk_v6_daddr.s6_addr32,
+						      inet->inet_sport,
+						      inet->inet_dport);
+	err = dccp_connect(sk);
+	if (err)
+		goto late_failure;
+
+	return 0;
+
+late_failure:
+	dccp_set_state(sk, DCCP_CLOSED);
+	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
+		inet_reset_saddr(sk);
+	__sk_dst_reset(sk);
+failure:
+	inet->inet_dport = 0;
+	sk->sk_route_caps = 0;
+	return err;
+}
+
+static const struct inet_connection_sock_af_ops dccp_ipv6_af_ops = {
+	.queue_xmit	   = inet6_csk_xmit,
+	.send_check	   = dccp_v6_send_check,
+	.rebuild_header	   = inet6_sk_rebuild_header,
+	.conn_request	   = dccp_v6_conn_request,
+	.syn_recv_sock	   = dccp_v6_request_recv_sock,
+	.net_header_len	   = sizeof(struct ipv6hdr),
+	.setsockopt	   = ipv6_setsockopt,
+	.getsockopt	   = ipv6_getsockopt,
+	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
+	.sockaddr_len	   = sizeof(struct sockaddr_in6),
+};
+
+/*
+ *	DCCP over IPv4 via INET6 API
+ */
+static const struct inet_connection_sock_af_ops dccp_ipv6_mapped = {
+	.queue_xmit	   = ip_queue_xmit,
+	.send_check	   = dccp_v4_send_check,
+	.rebuild_header	   = inet_sk_rebuild_header,
+	.conn_request	   = dccp_v6_conn_request,
+	.syn_recv_sock	   = dccp_v6_request_recv_sock,
+	.net_header_len	   = sizeof(struct iphdr),
+	.setsockopt	   = ipv6_setsockopt,
+	.getsockopt	   = ipv6_getsockopt,
+	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
+	.sockaddr_len	   = sizeof(struct sockaddr_in6),
+};
+
+static void dccp_v6_sk_destruct(struct sock *sk)
+{
+	dccp_destruct_common(sk);
+	inet6_sock_destruct(sk);
+}
+
+/* NOTE: A lot of things set to zero explicitly by call to
+ *       sk_alloc() so need not be done here.
+ */
+static int dccp_v6_init_sock(struct sock *sk)
+{
+	static __u8 dccp_v6_ctl_sock_initialized;
+	int err = dccp_init_sock(sk, dccp_v6_ctl_sock_initialized);
+
+	if (err == 0) {
+		if (unlikely(!dccp_v6_ctl_sock_initialized))
+			dccp_v6_ctl_sock_initialized = 1;
+		inet_csk(sk)->icsk_af_ops = &dccp_ipv6_af_ops;
+		sk->sk_destruct = dccp_v6_sk_destruct;
+	}
+
+	return err;
+}
+
+static struct timewait_sock_ops dccp6_timewait_sock_ops = {
+	.twsk_obj_size	= sizeof(struct dccp6_timewait_sock),
+};
+
+static struct proto dccp_v6_prot = {
+	.name		   = "DCCPv6",
+	.owner		   = THIS_MODULE,
+	.close		   = dccp_close,
+	.connect	   = dccp_v6_connect,
+	.disconnect	   = dccp_disconnect,
+	.ioctl		   = dccp_ioctl,
+	.init		   = dccp_v6_init_sock,
+	.setsockopt	   = dccp_setsockopt,
+	.getsockopt	   = dccp_getsockopt,
+	.sendmsg	   = dccp_sendmsg,
+	.recvmsg	   = dccp_recvmsg,
+	.backlog_rcv	   = dccp_v6_do_rcv,
+	.hash		   = inet6_hash,
+	.unhash		   = inet_unhash,
+	.accept		   = inet_csk_accept,
+	.get_port	   = inet_csk_get_port,
+	.shutdown	   = dccp_shutdown,
+	.destroy	   = dccp_destroy_sock,
+	.orphan_count	   = &dccp_orphan_count,
+	.max_header	   = MAX_DCCP_HEADER,
+	.obj_size	   = sizeof(struct dccp6_sock),
+	.slab_flags	   = SLAB_TYPESAFE_BY_RCU,
+	.rsk_prot	   = &dccp6_request_sock_ops,
+	.twsk_prot	   = &dccp6_timewait_sock_ops,
+	.h.hashinfo	   = &dccp_hashinfo,
+};
+
+static const struct inet6_protocol dccp_v6_protocol = {
+	.handler	= dccp_v6_rcv,
+	.err_handler	= dccp_v6_err,
+	.flags		= INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,
+};
+
+static const struct proto_ops inet6_dccp_ops = {
+	.family		   = PF_INET6,
+	.owner		   = THIS_MODULE,
+	.release	   = inet6_release,
+	.bind		   = inet6_bind,
+	.connect	   = inet_stream_connect,
+	.socketpair	   = sock_no_socketpair,
+	.accept		   = inet_accept,
+	.getname	   = inet6_getname,
+	.poll		   = dccp_poll,
+	.ioctl		   = inet6_ioctl,
+	.gettstamp	   = sock_gettstamp,
+	.listen		   = inet_dccp_listen,
+	.shutdown	   = inet_shutdown,
+	.setsockopt	   = sock_common_setsockopt,
+	.getsockopt	   = sock_common_getsockopt,
+	.sendmsg	   = inet_sendmsg,
+	.recvmsg	   = sock_common_recvmsg,
+	.mmap		   = sock_no_mmap,
+	.sendpage	   = sock_no_sendpage,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
+#endif
+};
+
+static struct inet_protosw dccp_v6_protosw = {
+	.type		= SOCK_DCCP,
+	.protocol	= IPPROTO_DCCP,
+	.prot		= &dccp_v6_prot,
+	.ops		= &inet6_dccp_ops,
+	.flags		= INET_PROTOSW_ICSK,
+};
+
+static int __net_init dccp_v6_init_net(struct net *net)
+{
+	if (dccp_hashinfo.bhash == NULL)
+		return -ESOCKTNOSUPPORT;
+
+	return inet_ctl_sock_create(&net->dccp.v6_ctl_sk, PF_INET6,
+				    SOCK_DCCP, IPPROTO_DCCP, net);
+}
+
+static void __net_exit dccp_v6_exit_net(struct net *net)
+{
+	inet_ctl_sock_destroy(net->dccp.v6_ctl_sk);
+}
+
+static void __net_exit dccp_v6_exit_batch(struct list_head *net_exit_list)
+{
+	inet_twsk_purge(&dccp_hashinfo, AF_INET6);
+}
+
+static struct pernet_operations dccp_v6_ops = {
+	.init   = dccp_v6_init_net,
+	.exit   = dccp_v6_exit_net,
+	.exit_batch = dccp_v6_exit_batch,
+};
+
+static int __init dccp_v6_init(void)
+{
+	int err = proto_register(&dccp_v6_prot, 1);
+
+	if (err)
+		goto out;
+
+	inet6_register_protosw(&dccp_v6_protosw);
+
+	err = register_pernet_subsys(&dccp_v6_ops);
+	if (err)
+		goto out_destroy_ctl_sock;
+
+	err = inet6_add_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
+	if (err)
+		goto out_unregister_proto;
+
+out:
+	return err;
+out_unregister_proto:
+	unregister_pernet_subsys(&dccp_v6_ops);
+out_destroy_ctl_sock:
+	inet6_unregister_protosw(&dccp_v6_protosw);
+	proto_unregister(&dccp_v6_prot);
+	goto out;
+}
+
+static void __exit dccp_v6_exit(void)
+{
+	inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
+	unregister_pernet_subsys(&dccp_v6_ops);
+	inet6_unregister_protosw(&dccp_v6_protosw);
+	proto_unregister(&dccp_v6_prot);
+}
+
+module_init(dccp_v6_init);
+module_exit(dccp_v6_exit);
+
+/*
+ * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
+ * values directly, Also cover the case where the protocol is not specified,
+ * i.e. net-pf-PF_INET6-proto-0-type-SOCK_DCCP
+ */
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 33, 6);
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 0, 6);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Arnaldo Carvalho de Melo <acme@mandriva.com>");
+MODULE_DESCRIPTION("DCCPv6 - Datagram Congestion Controlled Protocol");