diff options
Diffstat (limited to 'net/l2tp/l2tp_ip.c')
| -rw-r--r-- | net/l2tp/l2tp_ip.c | 704 |
1 files changed, 704 insertions, 0 deletions
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c new file mode 100644 index 000000000..99881b81f --- /dev/null +++ b/net/l2tp/l2tp_ip.c @@ -0,0 +1,704 @@ +/* + * 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. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <asm/ioctls.h> +#include <linux/icmp.h> +#include <linux/module.h> +#include <linux/skbuff.h> +#include <linux/random.h> +#include <linux/socket.h> +#include <linux/l2tp.h> +#include <linux/in.h> +#include <net/sock.h> +#include <net/ip.h> +#include <net/icmp.h> +#include <net/udp.h> +#include <net/inet_common.h> +#include <net/tcp_states.h> +#include <net/protocol.h> +#include <net/xfrm.h> + +#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; +}; + +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(const struct net *net, __be32 laddr, + __be32 raddr, int dif, u32 tunnel_id) +{ + struct sock *sk; + + sk_for_each_bound(sk, &l2tp_ip_bind_table) { + const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk); + const struct inet_sock *inet = inet_sk(sk); + + if (!net_eq(sock_net(sk), net)) + continue; + + if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif) + continue; + + if (inet->inet_rcv_saddr && laddr && + inet->inet_rcv_saddr != laddr) + continue; + + if (inet->inet_daddr && raddr && inet->inet_daddr != raddr) + continue; + + if (l2tp->conn_id != tunnel_id) + continue; + + goto found; + } + + sk = NULL; +found: + 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 net *net = dev_net(skb->dev); + struct sock *sk; + u32 session_id; + u32 tunnel_id; + unsigned char *ptr, *optr; + struct l2tp_session *session; + struct l2tp_tunnel *tunnel = NULL; + struct iphdr *iph; + int length; + + if (!pskb_may_pull(skb, 4)) + goto discard; + + /* Point to L2TP header */ + optr = ptr = skb->data; + 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_get(net, session_id); + if (!session) + goto discard; + + tunnel = session->tunnel; + if (!tunnel) + goto discard_sess; + + /* Trace packet contents, if enabled */ + if (tunnel->debug & L2TP_MSG_DATA) { + length = min(32u, skb->len); + if (!pskb_may_pull(skb, length)) + goto discard_sess; + + /* Point to L2TP header */ + optr = ptr = skb->data; + ptr += 4; + pr_debug("%s: ip recv\n", tunnel->name); + print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length); + } + + if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) + goto discard_sess; + + l2tp_recv_common(session, skb, ptr, optr, 0, skb->len); + l2tp_session_dec_refcount(session); + + 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]); + iph = (struct iphdr *)skb_network_header(skb); + + read_lock_bh(&l2tp_ip_lock); + sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb), + tunnel_id); + if (!sk) { + read_unlock_bh(&l2tp_ip_lock); + goto discard; + } + sock_hold(sk); + read_unlock_bh(&l2tp_ip_lock); + + if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) + goto discard_put; + + nf_reset(skb); + + return sk_receive_skb(sk, skb, 1); + +discard_sess: + l2tp_session_dec_refcount(session); + goto discard; + +discard_put: + sock_put(sk); + +discard: + kfree_skb(skb); + return 0; +} + +static int l2tp_ip_hash(struct sock *sk) +{ + if (sk_unhashed(sk)) { + 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_unhash(struct sock *sk) +{ + if (sk_unhashed(sk)) + return; + write_lock_bh(&l2tp_ip_lock); + sk_del_node_init(sk); + write_unlock_bh(&l2tp_ip_lock); +} + +static int l2tp_ip_open(struct sock *sk) +{ + /* Prevent autobind. We don't have ports. */ + inet_sk(sk)->inet_num = IPPROTO_L2TP; + + l2tp_ip_hash(sk); + 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); + sk_del_node_init(sk); + write_unlock_bh(&l2tp_ip_lock); + sk_common_release(sk); +} + +static void l2tp_ip_destroy_sock(struct sock *sk) +{ + struct sk_buff *skb; + struct l2tp_tunnel *tunnel = sk->sk_user_data; + + while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) + kfree_skb(skb); + + if (tunnel) + l2tp_tunnel_delete(tunnel); +} + +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; + struct net *net = sock_net(sk); + int ret; + int chk_addr_ret; + + if (addr_len < sizeof(struct sockaddr_l2tpip)) + return -EINVAL; + if (addr->l2tp_family != AF_INET) + return -EINVAL; + + lock_sock(sk); + + ret = -EINVAL; + if (!sock_flag(sk, SOCK_ZAPPED)) + goto out; + + if (sk->sk_state != TCP_CLOSE) + goto out; + + chk_addr_ret = inet_addr_type(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; + + if (addr->l2tp_addr.s_addr) + 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 */ + + write_lock_bh(&l2tp_ip_lock); + if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0, + sk->sk_bound_dev_if, addr->l2tp_conn_id)) { + write_unlock_bh(&l2tp_ip_lock); + ret = -EADDRINUSE; + goto out; + } + + sk_dst_reset(sk); + l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id; + + sk_add_bind_node(sk, &l2tp_ip_bind_table); + sk_del_node_init(sk); + write_unlock_bh(&l2tp_ip_lock); + + ret = 0; + sock_reset_flag(sk, SOCK_ZAPPED); + +out: + release_sock(sk); + + return ret; +} + +static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) +{ + struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr; + int rc; + + if (addr_len < sizeof(*lsa)) + return -EINVAL; + + if (ipv4_is_multicast(lsa->l2tp_addr.s_addr)) + return -EINVAL; + + lock_sock(sk); + + /* Must bind first - autobinding does not work */ + if (sock_flag(sk, SOCK_ZAPPED)) { + rc = -EINVAL; + goto out_sk; + } + + rc = __ip4_datagram_connect(sk, uaddr, addr_len); + if (rc < 0) + goto out_sk; + + l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id; + + 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); + +out_sk: + release_sock(sk); + + return rc; +} + +static int l2tp_ip_disconnect(struct sock *sk, int flags) +{ + if (sock_flag(sk, SOCK_ZAPPED)) + return 0; + + return __udp_disconnect(sk, flags); +} + +static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr, + 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; + } + return sizeof(*lsa); +} + +static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb) +{ + int rc; + + /* 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(sock_net(sk), IPSTATS_MIB_INDISCARDS); + kfree_skb(skb); + return 0; +} + +/* Userspace will call sendmsg() on the tunnel socket to send L2TP + * control frames. + */ +static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) +{ + struct sk_buff *skb; + int rc; + struct inet_sock *inet = inet_sk(sk); + struct rtable *rt = NULL; + struct flowi4 *fl4; + int connected = 0; + __be32 daddr; + + lock_sock(sk); + + rc = -ENOTCONN; + if (sock_flag(sk, SOCK_DEAD)) + goto out; + + /* Get and verify the address. */ + if (msg->msg_name) { + DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name); + rc = -EINVAL; + if (msg->msg_namelen < sizeof(*lip)) + goto out; + + if (lip->l2tp_family != AF_INET) { + rc = -EAFNOSUPPORT; + if (lip->l2tp_family != AF_UNSPEC) + goto out; + } + + daddr = lip->l2tp_addr.s_addr; + } else { + rc = -EDESTADDRREQ; + if (sk->sk_state != TCP_ESTABLISHED) + goto out; + + 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_from_msg(skb_put(skb, len), msg, len); + if (rc < 0) { + kfree_skb(skb); + goto error; + } + + fl4 = &inet->cork.fl.u.ip4; + if (connected) + rt = (struct rtable *) __sk_dst_check(sk, 0); + + rcu_read_lock(); + if (rt == NULL) { + const struct ip_options_rcu *inet_opt; + + inet_opt = rcu_dereference(inet->inet_opt); + + /* Use correct destination address if we have options. */ + if (inet_opt && inet_opt->opt.srr) + daddr = inet_opt->opt.faddr; + + /* If this fails, retransmit mechanism of transport layer will + * keep trying until route appears or the connection times + * itself out. + */ + rt = ip_route_output_ports(sock_net(sk), fl4, sk, + daddr, inet->inet_saddr, + inet->inet_dport, inet->inet_sport, + sk->sk_protocol, RT_CONN_FLAGS(sk), + sk->sk_bound_dev_if); + if (IS_ERR(rt)) + goto no_route; + if (connected) { + sk_setup_caps(sk, &rt->dst); + } else { + skb_dst_set(skb, &rt->dst); + goto xmit; + } + } + + /* We dont need to clone dst here, it is guaranteed to not disappear. + * __dev_xmit_skb() might force a refcount if needed. + */ + skb_dst_set_noref(skb, &rt->dst); + +xmit: + /* Queue the packet to IP for output */ + rc = ip_queue_xmit(sk, skb, &inet->cork.fl); + rcu_read_unlock(); + +error: + if (rc >= 0) + rc = len; + +out: + release_sock(sk); + return rc; + +no_route: + rcu_read_unlock(); + IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); + kfree_skb(skb); + rc = -EHOSTUNREACH; + goto out; +} + +static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg, + size_t len, int noblock, int flags, int *addr_len) +{ + struct inet_sock *inet = inet_sk(sk); + size_t copied = 0; + int err = -EOPNOTSUPP; + DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name); + struct sk_buff *skb; + + if (flags & MSG_OOB) + goto out; + + 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_msg(skb, 0, msg, 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)); + *addr_len = sizeof(*sin); + } + if (inet->cmsg_flags) + ip_cmsg_recv(msg, skb); + if (flags & MSG_TRUNC) + copied = skb->len; +done: + skb_free_datagram(sk, skb); +out: + return err ? err : copied; +} + +int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg) +{ + struct sk_buff *skb; + int amount; + + switch (cmd) { + case SIOCOUTQ: + amount = sk_wmem_alloc_get(sk); + break; + case SIOCINQ: + spin_lock_bh(&sk->sk_receive_queue.lock); + skb = skb_peek(&sk->sk_receive_queue); + amount = skb ? skb->len : 0; + spin_unlock_bh(&sk->sk_receive_queue.lock); + break; + + default: + return -ENOIOCTLCMD; + } + + return put_user(amount, (int __user *)arg); +} +EXPORT_SYMBOL(l2tp_ioctl); + +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 = l2tp_ip_disconnect, + .ioctl = l2tp_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 = l2tp_ip_hash, + .unhash = l2tp_ip_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, +}; + +static struct net_protocol l2tp_ip_protocol __read_mostly = { + .handler = l2tp_ip_recv, + .netns_ok = 1, +}; + +static int __init l2tp_ip_init(void) +{ + int err; + + pr_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 <jchapman@katalix.com>"); +MODULE_DESCRIPTION("L2TP over IP"); +MODULE_VERSION("1.0"); + +/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like + * enums + */ +MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP); +MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP); |