net: add PPP on PPTP Network Server (PPPoPNS) driver.

Signed-off-by: Chia-chi Yeh <chiachi@android.com>

ppopns: dont include px_proto define in if_pppopns.h

Change-Id: I27e687667db5b45182562f4a517a2e6cec6b1350
Signed-off-by: Dima Zavin <dima@android.com>

3 files changed, 331 insertions, 0 deletions

diff --git a/drivers/net/ppp/Kconfig b/drivers/net/ppp/Kconfig
index 382bd6fb07a..7936ae4cbf7 100644
--- a/drivers/net/ppp/Kconfig
+++ b/drivers/net/ppp/Kconfig
@@ -157,6 +157,14 @@ config PPPOLAC
 	  and a PPP channel, but only permits one session per socket. Thus it is
 	  fairly simple and suited for clients.
 
+config PPPOPNS
+	tristate "PPP on PPTP Network Server"
+	depends on PPP && INET
+	help
+	  PPTP (RFC 2637) is a tunneling protocol widely used in virtual private
+	  networks. This driver handles PPTP data packets between a RAW socket
+	  and a PPP channel. It is fairly simple and easy to use.
+
 config PPP_ASYNC
 	tristate "PPP support for async serial ports"
 	depends on PPP
diff --git a/drivers/net/ppp/Makefile b/drivers/net/ppp/Makefile
index f14406e0c38..d283d03c468 100644
--- a/drivers/net/ppp/Makefile
+++ b/drivers/net/ppp/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_PPPOE) += pppox.o pppoe.o
 obj-$(CONFIG_PPPOL2TP) += pppox.o
 obj-$(CONFIG_PPTP) += pppox.o pptp.o
 obj-$(CONFIG_PPPOLAC) += pppox.o pppolac.o
+obj-$(CONFIG_PPPOPNS) += pppox.o pppopns.o
diff --git a/drivers/net/ppp/pppopns.c b/drivers/net/ppp/pppopns.c
new file mode 100644
index 00000000000..8885eba8968
--- /dev/null
+++ b/drivers/net/ppp/pppopns.c
@@ -0,0 +1,322 @@
+/* drivers/net/pppopns.c
+ *
+ * Driver for PPP on PPTP Network Server / PPPoPNS Socket (RFC 2637)
+ *
+ * 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 PPTP data packets between a RAW socket and a PPP channel.
+ * The socket is created in the kernel space and connected to the same address
+ * of the control socket. To keep things simple, packets are always sent with
+ * sequence but without acknowledgement. This driver should work on both IPv4
+ * and IPv6. */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/file.h>
+#include <linux/net.h>
+#include <linux/ppp_defs.h>
+#include <linux/if.h>
+#include <linux/if_ppp.h>
+#include <linux/if_pppox.h>
+#include <linux/ppp_channel.h>
+
+#define GRE_HEADER_SIZE		8
+
+#define PPTP_GRE_MASK		htons(0x2001)
+#define PPTP_GRE_SEQ_MASK	htons(0x1000)
+#define PPTP_GRE_ACK_MASK	htons(0x0080)
+#define PPTP_GRE_TYPE		htons(0x880B)
+
+#define PPP_ADDR	0xFF
+#define PPP_CTRL	0x03
+
+struct header {
+	__u16	bits;
+	__u16	type;
+	__u16	length;
+	__u16	call;
+	__u32	sequence;
+} __attribute__((packed));
+
+static void pppopns_recv(struct sock *sk_raw, int length)
+{
+	struct sock *sk;
+	struct pppopns_opt *opt;
+	struct sk_buff *skb;
+	struct header *hdr;
+
+	/* Lock sk_raw to prevent sk from being closed. */
+	lock_sock(sk_raw);
+	sk = (struct sock *)sk_raw->sk_user_data;
+	if (!sk) {
+		release_sock(sk_raw);
+		return;
+	}
+	sock_hold(sk);
+	release_sock(sk_raw);
+	opt = &pppox_sk(sk)->proto.pns;
+
+	/* Process packets from the receive queue. */
+	while ((skb = skb_dequeue(&sk_raw->sk_receive_queue))) {
+		skb_pull(skb, skb_transport_header(skb) - skb->data);
+
+		/* Drop the packet if it is too short. */
+		if (skb->len < GRE_HEADER_SIZE)
+			goto drop;
+
+		/* Check the header. */
+		hdr = (struct header *)skb->data;
+		if (hdr->type != PPTP_GRE_TYPE || hdr->call != opt->local ||
+				(hdr->bits & PPTP_GRE_MASK) != PPTP_GRE_MASK)
+			goto drop;
+
+		/* Skip all fields including optional ones. */
+		if (!skb_pull(skb, GRE_HEADER_SIZE +
+				(hdr->bits & PPTP_GRE_SEQ_MASK ? 4 : 0) +
+				(hdr->bits & PPTP_GRE_ACK_MASK ? 4 : 0)))
+			goto drop;
+
+		/* Check the length. */
+		if (skb->len != ntohs(hdr->length))
+			goto drop;
+
+		/* 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;
+
+		/* 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);
+		continue;
+drop:
+		kfree_skb(skb);
+	}
+	sock_put(sk);
+}
+
+static int pppopns_xmit(struct ppp_channel *chan, struct sk_buff *skb)
+{
+	struct sock *sk_raw = (struct sock *)chan->private;
+	struct pppopns_opt *opt = &pppox_sk(sk_raw->sk_user_data)->proto.pns;
+	struct msghdr msg = {.msg_flags = MSG_NOSIGNAL | MSG_DONTWAIT};
+	struct kvec iov;
+	struct header *hdr;
+	__u16 length;
+
+	/* Install PPP address and control. */
+	skb_push(skb, 2);
+	skb->data[0] = PPP_ADDR;
+	skb->data[1] = PPP_CTRL;
+	length = skb->len;
+
+	/* Install PPTP GRE header. */
+	hdr = (struct header *)skb_push(skb, 12);
+	hdr->bits = PPTP_GRE_MASK | PPTP_GRE_SEQ_MASK;
+	hdr->type = PPTP_GRE_TYPE;
+	hdr->length = htons(length);
+	hdr->call = opt->remote;
+	hdr->sequence = htonl(opt->sequence);
+	opt->sequence++;
+
+	/* Now send the packet via RAW socket. */
+	iov.iov_base = skb->data;
+	iov.iov_len = skb->len;
+	kernel_sendmsg(sk_raw->sk_socket, &msg, &iov, 1, skb->len);
+	kfree_skb(skb);
+	return 1;
+}
+
+/******************************************************************************/
+
+static struct ppp_channel_ops pppopns_channel_ops = {
+	.start_xmit = pppopns_xmit,
+};
+
+static int pppopns_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_pppopns *addr = (struct sockaddr_pppopns *)useraddr;
+	struct sockaddr_storage ss;
+	struct socket *sock_tcp = NULL;
+	struct socket *sock_raw = NULL;
+	struct sock *sk_raw;
+	int error;
+
+	if (addrlen != sizeof(struct sockaddr_pppopns))
+		return -EINVAL;
+
+	lock_sock(sk);
+	error = -EALREADY;
+	if (sk->sk_state != PPPOX_NONE)
+		goto out;
+
+	sock_tcp = sockfd_lookup(addr->tcp_socket, &error);
+	if (!sock_tcp)
+		goto out;
+	error = -EPROTONOSUPPORT;
+	if (sock_tcp->sk->sk_protocol != IPPROTO_TCP)
+		goto out;
+	addrlen = sizeof(struct sockaddr_storage);
+	error = kernel_getpeername(sock_tcp, (struct sockaddr *)&ss, &addrlen);
+	if (error)
+		goto out;
+
+	error = sock_create(ss.ss_family, SOCK_RAW, IPPROTO_GRE, &sock_raw);
+	if (error)
+		goto out;
+	error = kernel_connect(sock_raw, (struct sockaddr *)&ss, addrlen, 0);
+	if (error)
+		goto out;
+	sk_raw = sock_raw->sk;
+
+	po->chan.hdrlen = 14;
+	po->chan.private = sk_raw;
+	po->chan.ops = &pppopns_channel_ops;
+	po->chan.mtu = PPP_MTU - 80;
+	po->proto.pns.local = addr->local;
+	po->proto.pns.remote = addr->remote;
+
+	error = ppp_register_channel(&po->chan);
+	if (error)
+		goto out;
+
+	sk->sk_state = PPPOX_CONNECTED;
+	sk_raw->sk_user_data = sk;
+	sk_raw->sk_data_ready = pppopns_recv;
+
+out:
+	if (sock_tcp)
+		sockfd_put(sock_tcp);
+	if (error && sock_raw)
+		sock_release(sock_raw);
+	release_sock(sk);
+	return error;
+}
+
+static int pppopns_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_raw = (struct sock *)pppox_sk(sk)->chan.private;
+		lock_sock(sk_raw);
+		pppox_unbind_sock(sk);
+		sk_raw->sk_user_data = NULL;
+		release_sock(sk_raw);
+		sock_release(sk_raw->sk_socket);
+	}
+
+	sock_orphan(sk);
+	sock->sk = NULL;
+	release_sock(sk);
+	sock_put(sk);
+	return 0;
+}
+
+/******************************************************************************/
+
+static struct proto pppopns_proto = {
+	.name = "PPPOPNS",
+	.owner = THIS_MODULE,
+	.obj_size = sizeof(struct pppox_sock),
+};
+
+static struct proto_ops pppopns_proto_ops = {
+	.family = PF_PPPOX,
+	.owner = THIS_MODULE,
+	.release = pppopns_release,
+	.bind = sock_no_bind,
+	.connect = pppopns_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 pppopns_create(struct net *net, struct socket *sock)
+{
+	struct sock *sk;
+
+	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppopns_proto);
+	if (!sk)
+		return -ENOMEM;
+
+	sock_init_data(sock, sk);
+	sock->state = SS_UNCONNECTED;
+	sock->ops = &pppopns_proto_ops;
+	sk->sk_protocol = PX_PROTO_OPNS;
+	sk->sk_state = PPPOX_NONE;
+	return 0;
+}
+
+/******************************************************************************/
+
+static struct pppox_proto pppopns_pppox_proto = {
+	.create = pppopns_create,
+	.owner = THIS_MODULE,
+};
+
+static int __init pppopns_init(void)
+{
+	int error;
+
+	error = proto_register(&pppopns_proto, 0);
+	if (error)
+		return error;
+
+	error = register_pppox_proto(PX_PROTO_OPNS, &pppopns_pppox_proto);
+	if (error)
+		proto_unregister(&pppopns_proto);
+	return error;
+}
+
+static void __exit pppopns_exit(void)
+{
+	unregister_pppox_proto(PX_PROTO_OPNS);
+	proto_unregister(&pppopns_proto);
+}
+
+module_init(pppopns_init);
+module_exit(pppopns_exit);
+
+MODULE_DESCRIPTION("PPP on PPTP Network Server (PPPoPNS)");
+MODULE_AUTHOR("Chia-chi Yeh <chiachi@android.com>");
+MODULE_LICENSE("GPL");