/* * L2TPv3 IP encapsulation support * * Copyright (c) 2008,2009,2010 Katalix Systems Ltd * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "l2tp_core.h" struct l2tp_ip_sock { /* inet_sock has to be the first member of l2tp_ip_sock */ struct inet_sock inet; __u32 conn_id; __u32 peer_conn_id; __u64 tx_packets; __u64 tx_bytes; __u64 tx_errors; __u64 rx_packets; __u64 rx_bytes; __u64 rx_errors; }; static DEFINE_RWLOCK(l2tp_ip_lock); static struct hlist_head l2tp_ip_table; static struct hlist_head l2tp_ip_bind_table; static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk) { return (struct l2tp_ip_sock *)sk; } static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id) { struct hlist_node *node; struct sock *sk; sk_for_each_bound(sk, node, &l2tp_ip_bind_table) { struct inet_sock *inet = inet_sk(sk); struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk); if (l2tp == NULL) continue; if ((l2tp->conn_id == tunnel_id) && net_eq(sock_net(sk), net) && !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) && !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)) goto found; } sk = NULL; found: return sk; } static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id) { struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id); if (sk) sock_hold(sk); return sk; } /* When processing receive frames, there are two cases to * consider. Data frames consist of a non-zero session-id and an * optional cookie. Control frames consist of a regular L2TP header * preceded by 32-bits of zeros. * * L2TPv3 Session Header Over IP * * 0 1 2 3 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Session ID | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Cookie (optional, maximum 64 bits)... * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * L2TPv3 Control Message Header Over IP * * 0 1 2 3 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | (32 bits of zeros) | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Control Connection ID | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Ns | Nr | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * All control frames are passed to userspace. */ static int l2tp_ip_recv(struct sk_buff *skb) { struct sock *sk; u32 session_id; u32 tunnel_id; unsigned char *ptr, *optr; struct l2tp_session *session; struct l2tp_tunnel *tunnel = NULL; int length; int offset; /* Point to L2TP header */ optr = ptr = skb->data; if (!pskb_may_pull(skb, 4)) goto discard; session_id = ntohl(*((__be32 *) ptr)); ptr += 4; /* RFC3931: L2TP/IP packets have the first 4 bytes containing * the session_id. If it is 0, the packet is a L2TP control * frame and the session_id value can be discarded. */ if (session_id == 0) { __skb_pull(skb, 4); goto pass_up; } /* Ok, this is a data packet. Lookup the session. */ session = l2tp_session_find(&init_net, NULL, session_id); if (session == NULL) goto discard; tunnel = session->tunnel; if (tunnel == NULL) goto discard; /* Trace packet contents, if enabled */ if (tunnel->debug & L2TP_MSG_DATA) { length = min(32u, skb->len); if (!pskb_may_pull(skb, length)) goto discard; printk(KERN_DEBUG "%s: ip recv: ", tunnel->name); offset = 0; do { printk(" %02X", ptr[offset]); } while (++offset < length); printk("\n"); } l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook); return 0; pass_up: /* Get the tunnel_id from the L2TP header */ if (!pskb_may_pull(skb, 12)) goto discard; if ((skb->data[0] & 0xc0) != 0xc0) goto discard; tunnel_id = ntohl(*(__be32 *) &skb->data[4]); tunnel = l2tp_tunnel_find(&init_net, tunnel_id); if (tunnel != NULL) sk = tunnel->sock; else { struct iphdr *iph = (struct iphdr *) skb_network_header(skb); read_lock_bh(&l2tp_ip_lock); sk = __l2tp_ip_bind_lookup(&init_net, iph->daddr, 0, tunnel_id); read_unlock_bh(&l2tp_ip_lock); } if (sk == NULL) goto discard; sock_hold(sk); if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_put; nf_reset(skb); return sk_receive_skb(sk, skb, 1); discard_put: sock_put(sk); discard: kfree_skb(skb); return 0; } static int l2tp_ip_open(struct sock *sk) { /* Prevent autobind. We don't have ports. */ inet_sk(sk)->inet_num = IPPROTO_L2TP; write_lock_bh(&l2tp_ip_lock); sk_add_node(sk, &l2tp_ip_table); write_unlock_bh(&l2tp_ip_lock); return 0; } static void l2tp_ip_close(struct sock *sk, long timeout) { write_lock_bh(&l2tp_ip_lock); hlist_del_init(&sk->sk_bind_node); hlist_del_init(&sk->sk_node); write_unlock_bh(&l2tp_ip_lock); sk_common_release(sk); } static void l2tp_ip_destroy_sock(struct sock *sk) { struct sk_buff *skb; while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) kfree_skb(skb); sk_refcnt_debug_dec(sk); } static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len) { struct inet_sock *inet = inet_sk(sk); struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr; int ret = -EINVAL; int chk_addr_ret; ret = -EADDRINUSE; read_lock_bh(&l2tp_ip_lock); if (__l2tp_ip_bind_lookup(&init_net, addr->l2tp_addr.s_addr, sk->sk_bound_dev_if, addr->l2tp_conn_id)) goto out_in_use; read_unlock_bh(&l2tp_ip_lock); lock_sock(sk); if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip)) goto out; chk_addr_ret = inet_addr_type(&init_net, addr->l2tp_addr.s_addr); ret = -EADDRNOTAVAIL; if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL && chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST) goto out; inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr; if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST) inet->inet_saddr = 0; /* Use device */ sk_dst_reset(sk); l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id; write_lock_bh(&l2tp_ip_lock); sk_add_bind_node(sk, &l2tp_ip_bind_table); sk_del_node_init(sk); write_unlock_bh(&l2tp_ip_lock); ret = 0; out: release_sock(sk); return ret; out_in_use: read_unlock_bh(&l2tp_ip_lock); return ret; } static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) { int rc; struct inet_sock *inet = inet_sk(sk); struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr; struct rtable *rt; __be32 saddr; int oif; rc = -EINVAL; if (addr_len < sizeof(*lsa)) goto out; rc = -EAFNOSUPPORT; if (lsa->l2tp_family != AF_INET) goto out; sk_dst_reset(sk); oif = sk->sk_bound_dev_if; saddr = inet->inet_saddr; rc = -EINVAL; if (ipv4_is_multicast(lsa->l2tp_addr.s_addr)) goto out; rc = ip_route_connect(&rt, lsa->l2tp_addr.s_addr, saddr, RT_CONN_FLAGS(sk), oif, IPPROTO_L2TP, 0, 0, sk, 1); if (rc) { if (rc == -ENETUNREACH) IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES); goto out; } rc = -ENETUNREACH; if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) { ip_rt_put(rt); goto out; } l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id; if (!inet->inet_saddr) inet->inet_saddr = rt->rt_src; if (!inet->inet_rcv_saddr) inet->inet_rcv_saddr = rt->rt_src; inet->inet_daddr = rt->rt_dst; sk->sk_state = TCP_ESTABLISHED; inet->inet_id = jiffies; sk_dst_set(sk, &rt->dst); write_lock_bh(&l2tp_ip_lock); hlist_del_init(&sk->sk_bind_node); sk_add_bind_node(sk, &l2tp_ip_bind_table); write_unlock_bh(&l2tp_ip_lock); rc = 0; out: return rc; } static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr, int *uaddr_len, int peer) { struct sock *sk = sock->sk; struct inet_sock *inet = inet_sk(sk); struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk); struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr; memset(lsa, 0, sizeof(*lsa)); lsa->l2tp_family = AF_INET; if (peer) { if (!inet->inet_dport) return -ENOTCONN; lsa->l2tp_conn_id = lsk->peer_conn_id; lsa->l2tp_addr.s_addr = inet->inet_daddr; } else { __be32 addr = inet->inet_rcv_saddr; if (!addr) addr = inet->inet_saddr; lsa->l2tp_conn_id = lsk->conn_id; lsa->l2tp_addr.s_addr = addr; } *uaddr_len = sizeof(*lsa); return 0; } static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb) { int rc; if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) goto drop; nf_reset(skb); /* Charge it to the socket, dropping if the queue is full. */ rc = sock_queue_rcv_skb(sk, skb); if (rc < 0) goto drop; return 0; drop: IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS); kfree_skb(skb); return -1; } /* Userspace will call sendmsg() on the tunnel socket to send L2TP * control frames. */ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len) { struct sk_buff *skb; int rc; struct l2tp_ip_sock *lsa = l2tp_ip_sk(sk); struct inet_sock *inet = inet_sk(sk); struct ip_options *opt = inet->opt; struct rtable *rt = NULL; int connected = 0; __be32 daddr; if (sock_flag(sk, SOCK_DEAD)) return -ENOTCONN; /* Get and verify the address. */ if (msg->msg_name) { struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name; if (msg->msg_namelen < sizeof(*lip)) return -EINVAL; if (lip->l2tp_family != AF_INET) { if (lip->l2tp_family != AF_UNSPEC) return -EAFNOSUPPORT; } daddr = lip->l2tp_addr.s_addr; } else { if (sk->sk_state != TCP_ESTABLISHED) return -EDESTADDRREQ; daddr = inet->inet_daddr; connected = 1; } /* Allocate a socket buffer */ rc = -ENOMEM; skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) + 4 + len, 0, GFP_KERNEL); if (!skb) goto error; /* Reserve space for headers, putting IP header on 4-byte boundary. */ skb_reserve(skb, 2 + NET_SKB_PAD); skb_reset_network_header(skb); skb_reserve(skb, sizeof(struct iphdr)); skb_reset_transport_header(skb); /* Insert 0 session_id */ *((__be32 *) skb_put(skb, 4)) = 0; /* Copy user data into skb */ rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len); if (rc < 0) { kfree_skb(skb); goto error; } if (connected) rt = (struct rtable *) __sk_dst_check(sk, 0); if (rt == NULL) { /* Use correct destination address if we have options. */ if (opt && opt->srr) daddr = opt->faddr; { struct flowi fl = { .oif = sk->sk_bound_dev_if, .nl_u = { .ip4_u = { .daddr = daddr, .saddr = inet->inet_saddr, .tos = RT_CONN_FLAGS(sk) } }, .proto = sk->sk_protocol, .flags = inet_sk_flowi_flags(sk), .uli_u = { .ports = { .sport = inet->inet_sport, .dport = inet->inet_dport } } }; /* If this fails, retransmit mechanism of transport layer will * keep trying until route appears or the connection times * itself out. */ security_sk_classify_flow(sk, &fl); if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0)) goto no_route; } sk_setup_caps(sk, &rt->dst); } skb_dst_set(skb, dst_clone(&rt->dst)); /* Queue the packet to IP for output */ rc = ip_queue_xmit(skb); error: /* Update stats */ if (rc >= 0) { lsa->tx_packets++; lsa->tx_bytes += len; rc = len; } else { lsa->tx_errors++; } return rc; no_route: IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); kfree_skb(skb); return -EHOSTUNREACH; } static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len, int noblock, int flags, int *addr_len) { struct inet_sock *inet = inet_sk(sk); struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk); size_t copied = 0; int err = -EOPNOTSUPP; struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name; struct sk_buff *skb; if (flags & MSG_OOB) goto out; if (addr_len) *addr_len = sizeof(*sin); skb = skb_recv_datagram(sk, flags, noblock, &err); if (!skb) goto out; copied = skb->len; if (len < copied) { msg->msg_flags |= MSG_TRUNC; copied = len; } err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied); if (err) goto done; sock_recv_timestamp(msg, sk, skb); /* Copy the address. */ if (sin) { sin->sin_family = AF_INET; sin->sin_addr.s_addr = ip_hdr(skb)->saddr; sin->sin_port = 0; memset(&sin->sin_zero, 0, sizeof(sin->sin_zero)); } if (inet->cmsg_flags) ip_cmsg_recv(msg, skb); if (flags & MSG_TRUNC) copied = skb->len; done: skb_free_datagram(sk, skb); out: if (err) { lsk->rx_errors++; return err; } lsk->rx_packets++; lsk->rx_bytes += copied; return copied; } static struct proto l2tp_ip_prot = { .name = "L2TP/IP", .owner = THIS_MODULE, .init = l2tp_ip_open, .close = l2tp_ip_close, .bind = l2tp_ip_bind, .connect = l2tp_ip_connect, .disconnect = udp_disconnect, .ioctl = udp_ioctl, .destroy = l2tp_ip_destroy_sock, .setsockopt = ip_setsockopt, .getsockopt = ip_getsockopt, .sendmsg = l2tp_ip_sendmsg, .recvmsg = l2tp_ip_recvmsg, .backlog_rcv = l2tp_ip_backlog_recv, .hash = inet_hash, .unhash = inet_unhash, .obj_size = sizeof(struct l2tp_ip_sock), #ifdef CONFIG_COMPAT .compat_setsockopt = compat_ip_setsockopt, .compat_getsockopt = compat_ip_getsockopt, #endif }; static const struct proto_ops l2tp_ip_ops = { .family = PF_INET, .owner = THIS_MODULE, .release = inet_release, .bind = inet_bind, .connect = inet_dgram_connect, .socketpair = sock_no_socketpair, .accept = sock_no_accept, .getname = l2tp_ip_getname, .poll = datagram_poll, .ioctl = inet_ioctl, .listen = sock_no_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_setsockopt = compat_sock_common_setsockopt, .compat_getsockopt = compat_sock_common_getsockopt, #endif }; static struct inet_protosw l2tp_ip_protosw = { .type = SOCK_DGRAM, .protocol = IPPROTO_L2TP, .prot = &l2tp_ip_prot, .ops = &l2tp_ip_ops, .no_check = 0, }; static struct net_protocol l2tp_ip_protocol __read_mostly = { .handler = l2tp_ip_recv, }; static int __init l2tp_ip_init(void) { int err; printk(KERN_INFO "L2TP IP encapsulation support (L2TPv3)\n"); err = proto_register(&l2tp_ip_prot, 1); if (err != 0) goto out; err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP); if (err) goto out1; inet_register_protosw(&l2tp_ip_protosw); return 0; out1: proto_unregister(&l2tp_ip_prot); out: return err; } static void __exit l2tp_ip_exit(void) { inet_unregister_protosw(&l2tp_ip_protosw); inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP); proto_unregister(&l2tp_ip_prot); } module_init(l2tp_ip_init); module_exit(l2tp_ip_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("James Chapman "); MODULE_DESCRIPTION("L2TP over IP"); MODULE_VERSION("1.0"); MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, SOCK_DGRAM, IPPROTO_L2TP);