--- /dev/null
+/* drivers/net/pppolac.c
+ *
+ * Driver for PPP on L2TP Access Concentrator / PPPoLAC Socket (RFC 2661)
+ *
+ * Copyright (C) 2009 Google, Inc.
+ * Author: Chia-chi Yeh <chiachi@android.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+/* This driver handles L2TP data packets between a UDP socket and a PPP channel.
+ * To keep things simple, only one session per socket is permitted. Packets are
+ * sent via the socket, so it must keep connected to the same address. One must
+ * not set sequencing in ICCN but let LNS controll it. Currently this driver
+ * only works on IPv4 due to the lack of UDP encapsulation support in IPv6. */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/file.h>
+#include <linux/net.h>
+#include <linux/udp.h>
+#include <linux/ppp_defs.h>
+#include <linux/if_ppp.h>
+#include <linux/if_pppox.h>
+#include <linux/ppp_channel.h>
+#include <net/tcp_states.h>
+
+#define L2TP_CONTROL_MASK 0x80
+#define L2TP_VERSION_MASK 0x0F
+#define L2TP_VERSION 0x02
+#define L2TP_LENGTH_MASK 0x40
+#define L2TP_OFFSET_MASK 0x02
+#define L2TP_SEQUENCE_MASK 0x08
+
+#define PPP_ADDR 0xFF
+#define PPP_CTRL 0x03
+
+union unaligned {
+ __u32 u32;
+} __attribute__((packed));
+
+static inline union unaligned *unaligned(void *ptr)
+{
+ return (union unaligned *)ptr;
+}
+
+static int pppolac_recv(struct sock *sk_udp, struct sk_buff *skb)
+{
+ struct sock *sk;
+ struct pppolac_opt *opt;
+ __u8 bits;
+ __u8 *ptr;
+
+ /* Drop the packet if it is too short. */
+ if (skb->len < sizeof(struct udphdr) + 6)
+ goto drop;
+
+ /* Put it back if it is a control packet. */
+ if (skb->data[sizeof(struct udphdr)] & L2TP_CONTROL_MASK)
+ return 1;
+
+ /* Now the packet is ours. Skip UDP header. */
+ skb_pull(skb, sizeof(struct udphdr));
+
+ /* Check the version. */
+ if ((skb->data[1] & L2TP_VERSION_MASK) != L2TP_VERSION)
+ goto drop;
+ bits = skb->data[0];
+ ptr = &skb->data[2];
+
+ /* Check the length if it is present. */
+ if (bits & L2TP_LENGTH_MASK) {
+ if ((ptr[0] << 8 | ptr[1]) != skb->len)
+ goto drop;
+ ptr += 2;
+ }
+
+ /* Skip all fields including optional ones. */
+ if (!skb_pull(skb, 6 + (bits & L2TP_SEQUENCE_MASK ? 4 : 0) +
+ (bits & L2TP_LENGTH_MASK ? 2 : 0) +
+ (bits & L2TP_OFFSET_MASK ? 2 : 0)))
+ goto drop;
+
+ /* Skip the offset padding if it is present. */
+ if (bits & L2TP_OFFSET_MASK &&
+ !skb_pull(skb, skb->data[-2] << 8 | skb->data[-1]))
+ goto drop;
+
+ /* Now ptr is pointing to the tunnel and skb is pointing to the payload.
+ * We have to lock sk_udp to prevent sk from being closed. */
+ lock_sock(sk_udp);
+ sk = sk_udp->sk_user_data;
+ if (!sk) {
+ release_sock(sk_udp);
+ goto drop;
+ }
+ sock_hold(sk);
+ release_sock(sk_udp);
+ opt = &pppox_sk(sk)->proto.lac;
+
+ /* Check the tunnel and the session. */
+ if (unaligned(ptr)->u32 != opt->local) {
+ sock_put(sk);
+ goto drop;
+ }
+
+ /* Check the sequence if it is present. According to RFC 2661 page 10
+ * and 43, the only thing to do is updating opt->sequencing. */
+ opt->sequencing = bits & L2TP_SEQUENCE_MASK;
+
+ /* Skip PPP address and control if they are present. */
+ if (skb->len >= 2 && skb->data[0] == PPP_ADDR &&
+ skb->data[1] == PPP_CTRL)
+ skb_pull(skb, 2);
+
+ /* Fix PPP protocol if it is compressed. */
+ if (skb->len >= 1 && skb->data[0] & 1)
+ skb_push(skb, 1)[0] = 0;
+
+ /* Finally, deliver the packet to PPP channel. We have to lock sk to
+ * prevent another thread from calling pppox_unbind_sock(). */
+ skb_orphan(skb);
+ lock_sock(sk);
+ ppp_input(&pppox_sk(sk)->chan, skb);
+ release_sock(sk);
+ sock_put(sk);
+ return 0;
+
+drop:
+ kfree_skb(skb);
+ return 0;
+}
+
+static int pppolac_xmit(struct ppp_channel *chan, struct sk_buff *skb)
+{
+ struct sock *sk_udp = (struct sock *)chan->private;
+ struct pppolac_opt *opt = &pppox_sk(sk_udp->sk_user_data)->proto.lac;
+ struct msghdr msg = {.msg_flags = MSG_NOSIGNAL | MSG_DONTWAIT};
+ struct kvec iov;
+
+ /* Install PPP address and control. */
+ skb_push(skb, 2);
+ skb->data[0] = PPP_ADDR;
+ skb->data[1] = PPP_CTRL;
+
+ /* Install L2TP header. */
+ if (opt->sequencing) {
+ skb_push(skb, 10);
+ skb->data[0] = L2TP_SEQUENCE_MASK;
+ skb->data[6] = opt->sequence >> 8;
+ skb->data[7] = opt->sequence;
+ skb->data[8] = 0;
+ skb->data[9] = 0;
+ opt->sequence++;
+ } else {
+ skb_push(skb, 6);
+ skb->data[0] = 0;
+ }
+ skb->data[1] = L2TP_VERSION;
+ unaligned(&skb->data[2])->u32 = opt->remote;
+
+ /* Now send the packet via UDP socket. */
+ iov.iov_base = skb->data;
+ iov.iov_len = skb->len;
+ kernel_sendmsg(sk_udp->sk_socket, &msg, &iov, 1, skb->len);
+ kfree_skb(skb);
+ return 1;
+}
+
+/******************************************************************************/
+
+static struct ppp_channel_ops pppolac_channel_ops = {
+ .start_xmit = pppolac_xmit,
+};
+
+static int pppolac_connect(struct socket *sock, struct sockaddr *useraddr,
+ int addrlen, int flags)
+{
+ struct sock *sk = sock->sk;
+ struct pppox_sock *po = pppox_sk(sk);
+ struct sockaddr_pppolac *addr = (struct sockaddr_pppolac *)useraddr;
+ struct socket *sock_udp = NULL;
+ struct sock *sk_udp;
+ int error;
+
+ if (addrlen != sizeof(struct sockaddr_pppolac) ||
+ !addr->local.tunnel || !addr->local.session ||
+ !addr->remote.tunnel || !addr->remote.session) {
+ return -EINVAL;
+ }
+
+ lock_sock(sk);
+ error = -EALREADY;
+ if (sk->sk_state != PPPOX_NONE)
+ goto out;
+
+ sock_udp = sockfd_lookup(addr->udp_socket, &error);
+ if (!sock_udp)
+ goto out;
+ sk_udp = sock_udp->sk;
+ lock_sock(sk_udp);
+
+ /* Remove this check when IPv6 supports UDP encapsulation. */
+ error = -EAFNOSUPPORT;
+ if (sk_udp->sk_family != AF_INET)
+ goto out;
+ error = -EPROTONOSUPPORT;
+ if (sk_udp->sk_protocol != IPPROTO_UDP)
+ goto out;
+ error = -EDESTADDRREQ;
+ if (sk_udp->sk_state != TCP_ESTABLISHED)
+ goto out;
+ error = -EBUSY;
+ if (udp_sk(sk_udp)->encap_type || sk_udp->sk_user_data)
+ goto out;
+
+ po->chan.hdrlen = 12;
+ po->chan.private = sk_udp;
+ po->chan.ops = &pppolac_channel_ops;
+ po->chan.mtu = PPP_MTU - 80;
+ po->proto.lac.local = unaligned(&addr->local)->u32;
+ po->proto.lac.remote = unaligned(&addr->remote)->u32;
+
+ error = ppp_register_channel(&po->chan);
+ if (error)
+ goto out;
+
+ sk->sk_state = PPPOX_CONNECTED;
+ udp_sk(sk_udp)->encap_type = UDP_ENCAP_L2TPINUDP;
+ udp_sk(sk_udp)->encap_rcv = pppolac_recv;
+ sk_udp->sk_user_data = sk;
+
+out:
+ if (sock_udp) {
+ release_sock(sk_udp);
+ if (error)
+ sockfd_put(sock_udp);
+ }
+ release_sock(sk);
+ return error;
+}
+
+static int pppolac_release(struct socket *sock)
+{
+ struct sock *sk = sock->sk;
+
+ if (!sk)
+ return 0;
+
+ lock_sock(sk);
+ if (sock_flag(sk, SOCK_DEAD)) {
+ release_sock(sk);
+ return -EBADF;
+ }
+
+ if (sk->sk_state != PPPOX_NONE) {
+ struct sock *sk_udp = (struct sock *)pppox_sk(sk)->chan.private;
+ lock_sock(sk_udp);
+
+ pppox_unbind_sock(sk);
+ sk_udp->sk_user_data = NULL;
+ udp_sk(sk_udp)->encap_type = 0;
+ udp_sk(sk_udp)->encap_rcv = NULL;
+
+ release_sock(sk_udp);
+ sockfd_put(sk_udp->sk_socket);
+ }
+
+ sock_orphan(sk);
+ sock->sk = NULL;
+ release_sock(sk);
+ sock_put(sk);
+ return 0;
+}
+
+/******************************************************************************/
+
+static struct proto pppolac_proto = {
+ .name = "PPPOLAC",
+ .owner = THIS_MODULE,
+ .obj_size = sizeof(struct pppox_sock),
+};
+
+static struct proto_ops pppolac_proto_ops = {
+ .family = PF_PPPOX,
+ .owner = THIS_MODULE,
+ .release = pppolac_release,
+ .bind = sock_no_bind,
+ .connect = pppolac_connect,
+ .socketpair = sock_no_socketpair,
+ .accept = sock_no_accept,
+ .getname = sock_no_getname,
+ .poll = sock_no_poll,
+ .ioctl = pppox_ioctl,
+ .listen = sock_no_listen,
+ .shutdown = sock_no_shutdown,
+ .setsockopt = sock_no_setsockopt,
+ .getsockopt = sock_no_getsockopt,
+ .sendmsg = sock_no_sendmsg,
+ .recvmsg = sock_no_recvmsg,
+ .mmap = sock_no_mmap,
+};
+
+static int pppolac_create(struct net *net, struct socket *sock)
+{
+ struct sock *sk;
+
+ sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppolac_proto);
+ if (!sk)
+ return -ENOMEM;
+
+ sock_init_data(sock, sk);
+ sock->state = SS_UNCONNECTED;
+ sock->ops = &pppolac_proto_ops;
+ sk->sk_protocol = PX_PROTO_OLAC;
+ sk->sk_state = PPPOX_NONE;
+ return 0;
+}
+
+/******************************************************************************/
+
+static struct pppox_proto pppolac_pppox_proto = {
+ .create = pppolac_create,
+ .owner = THIS_MODULE,
+};
+
+static int __init pppolac_init(void)
+{
+ int error;
+
+ error = proto_register(&pppolac_proto, 0);
+ if (error)
+ return error;
+
+ error = register_pppox_proto(PX_PROTO_OLAC, &pppolac_pppox_proto);
+ if (error)
+ proto_unregister(&pppolac_proto);
+ return error;
+}
+
+static void __exit pppolac_exit(void)
+{
+ unregister_pppox_proto(PX_PROTO_OLAC);
+ proto_unregister(&pppolac_proto);
+}
+
+module_init(pppolac_init);
+module_exit(pppolac_exit);
+
+MODULE_DESCRIPTION("PPP on L2TP Access Concentrator (PPPoLAC)");
+MODULE_AUTHOR("Chia-chi Yeh <chiachi@android.com>");
+MODULE_LICENSE("GPL");
projects / GitHub / exynos8895 / android_kernel_samsung_universal8895.git / commitdiff