path: root/net/dccp/ipv4.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  net/dccp/ipv4.c
 *
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 */

#include <linux/dccp.h>
#include <linux/icmp.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/random.h>

#include <net/icmp.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/inet_sock.h>
#include <net/protocol.h>
#include <net/sock.h>
#include <net/timewait_sock.h>
#include <net/tcp_states.h>
#include <net/xfrm.h>
#include <net/secure_seq.h>
#include <net/netns/generic.h>

#include "ackvec.h"
#include "ccid.h"
#include "dccp.h"
#include "feat.h"

struct dccp_v4_pernet {
	struct sock *v4_ctl_sk;
};

static unsigned int dccp_v4_pernet_id __read_mostly;

/*
 * The per-net v4_ctl_sk socket is used for responding to
 * the Out-of-the-blue (OOTB) packets. A control sock will be created
 * for this socket at the initialization time.
 */

int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
	const struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
	struct inet_bind_hashbucket *prev_addr_hashbucket = NULL;
	__be32 daddr, nexthop, prev_sk_rcv_saddr;
	struct inet_sock *inet = inet_sk(sk);
	struct dccp_sock *dp = dccp_sk(sk);
	__be16 orig_sport, orig_dport;
	struct flowi4 *fl4;
	struct rtable *rt;
	int err;
	struct ip_options_rcu *inet_opt;

	dp->dccps_role = DCCP_ROLE_CLIENT;

	if (addr_len < sizeof(struct sockaddr_in))
		return -EINVAL;

	if (usin->sin_family != AF_INET)
		return -EAFNOSUPPORT;

	nexthop = daddr = usin->sin_addr.s_addr;

	inet_opt = rcu_dereference_protected(inet->inet_opt,
					     lockdep_sock_is_held(sk));
	if (inet_opt != NULL && inet_opt->opt.srr) {
		if (daddr == 0)
			return -EINVAL;
		nexthop = inet_opt->opt.faddr;
	}

	orig_sport = inet->inet_sport;
	orig_dport = usin->sin_port;
	fl4 = &inet->cork.fl.u.ip4;
	rt = ip_route_connect(fl4, nexthop, inet->inet_saddr,
			      sk->sk_bound_dev_if, IPPROTO_DCCP, orig_sport,
			      orig_dport, sk);
	if (IS_ERR(rt))
		return PTR_ERR(rt);

	if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
		ip_rt_put(rt);
		return -ENETUNREACH;
	}

	if (inet_opt == NULL || !inet_opt->opt.srr)
		daddr = fl4->daddr;

	if (inet->inet_saddr == 0) {
		if (inet_csk(sk)->icsk_bind2_hash) {
			prev_addr_hashbucket =
				inet_bhashfn_portaddr(&dccp_hashinfo, sk,
						      sock_net(sk),
						      inet->inet_num);
			prev_sk_rcv_saddr = sk->sk_rcv_saddr;
		}
		inet->inet_saddr = fl4->saddr;
	}

	sk_rcv_saddr_set(sk, inet->inet_saddr);

	if (prev_addr_hashbucket) {
		err = inet_bhash2_update_saddr(prev_addr_hashbucket, sk);
		if (err) {
			inet->inet_saddr = 0;
			sk_rcv_saddr_set(sk, prev_sk_rcv_saddr);
			ip_rt_put(rt);
			return err;
		}
	}

	inet->inet_dport = usin->sin_port;
	sk_daddr_set(sk, daddr);

	inet_csk(sk)->icsk_ext_hdr_len = 0;
	if (inet_opt)
		inet_csk(sk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
	/*
	 * Socket identity is still unknown (sport may be zero).
	 * However we set state to DCCP_REQUESTING and not releasing socket
	 * lock select source port, enter ourselves into the hash tables and
	 * complete initialization after this.
	 */
	dccp_set_state(sk, DCCP_REQUESTING);
	err = inet_hash_connect(&dccp_death_row, sk);
	if (err != 0)
		goto failure;

	rt = ip_route_newports(fl4, rt, orig_sport, orig_dport,
			       inet->inet_sport, inet->inet_dport, sk);
	if (IS_ERR(rt)) {
		err = PTR_ERR(rt);
		rt = NULL;
		goto failure;
	}
	/* OK, now commit destination to socket.  */
	sk_setup_caps(sk, &rt->dst);

	dp->dccps_iss = secure_dccp_sequence_number(inet->inet_saddr,
						    inet->inet_daddr,
						    inet->inet_sport,
						    inet->inet_dport);
	inet->inet