Date:	Sun, 22 Feb 2009 17:52:20 GMT
From:	James Chapman <jchapman@...alix.com>
To:	netdev@...r.kernel.org
Subject: [RFC PATCH 4/8] l2tp: add L2TPv3 PPP pseudowire support

This patch makes changes to the L2TP PPP code for L2TPv3.

The existing code has some assumptions about the L2TP header which are
broken by L2TPv3. Also the sockaddr_pppol2tp structure of the original
code is too small to support the increased size of the L2TPv3 tunnel
and session id, so a new sockaddr_pppol2tpv3 structure is needed. In
the socket calls, the size of this structure is used to tell if the
operation is for L2TPv2 or L2TPv3.

Index: net-next-2.6-l2tpv3-2/net/l2tp/l2tp_ppp.c
===================================================================
--- net-next-2.6-l2tpv3-2.orig/net/l2tp/l2tp_ppp.c
+++ net-next-2.6-l2tpv3-2/net/l2tp/l2tp_ppp.c
@@ -297,17 +297,6 @@ static void pppol2tp_session_sock_put(st
  * Transmit handling
  ***********************************************************************/
 
-/* Tell how big L2TP headers are for a particular session. This
- * depends on whether sequence numbers are being used.
- */
-static inline int pppol2tp_l2tp_header_len(struct l2tp_session *session)
-{
-	if (session->send_seq)
-		return PPPOL2TP_L2TP_HDR_SIZE_SEQ;
-
-	return PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
-}
-
 /* This is the sendmsg for the PPPoL2TP pppol2tp_session socket.  We come here
  * when a user application does a sendmsg() on the session socket. L2TP and
  * PPP headers must be inserted into the user's data.
@@ -321,7 +310,6 @@ static int pppol2tp_sendmsg(struct kiocb
 	__wsum csum = 0;
 	struct sk_buff *skb;
 	int error;
-	int hdr_len;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
 	struct udphdr *uh;
@@ -342,13 +330,10 @@ static int pppol2tp_sendmsg(struct kiocb
 	if (tunnel == NULL)
 		goto error_put_sess;
 
-	/* What header length is configured for this session? */
-	hdr_len = pppol2tp_l2tp_header_len(session);
-
 	/* Allocate a socket buffer */
 	error = -ENOMEM;
 	skb = sock_wmalloc(sk, NET_SKB_PAD + sizeof(struct iphdr) +
-			   sizeof(struct udphdr) + hdr_len +
+			   sizeof(struct udphdr) + session->header_len +
 			   sizeof(ppph) + total_len,
 			   0, GFP_KERNEL);
 	if (!skb)
@@ -365,13 +350,13 @@ static int pppol2tp_sendmsg(struct kiocb
 	uh = (struct udphdr *) skb->data;
 	uh->source = inet->sport;
 	uh->dest = inet->dport;
-	uh->len = htons(hdr_len + sizeof(ppph) + total_len);
+	uh->len = htons(session->header_len + sizeof(ppph) + total_len);
 	uh->check = 0;
 	skb_put(skb, sizeof(struct udphdr));
 
 	/* Build L2TP header */
 	session->build_header(session, skb->data);
-	skb_put(skb, hdr_len);
+	skb_put(skb, session->header_len);
 
 	/* Add PPP header */
 	skb->data[0] = ppph[0];
@@ -421,7 +406,6 @@ static int pppol2tp_xmit(struct ppp_chan
 	static const u8 ppph[2] = { 0xff, 0x03 };
 	struct sock *sk = (struct sock *) chan->private;
 	struct sock *sk_tun;
-	int hdr_len;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
 	struct pppol2tp_session *ps;
@@ -442,9 +426,6 @@ static int pppol2tp_xmit(struct ppp_chan
 	if (tunnel == NULL)
 		goto abort_put_sess;
 
-	/* What header length is configured for this session? */
-	hdr_len = pppol2tp_l2tp_header_len(session);
-
  	if (skb_cow_head(skb, sizeof(ppph)))
 		goto abort_put_sess_tun;
 
@@ -453,7 +434,7 @@ static int pppol2tp_xmit(struct ppp_chan
 	skb->data[0] = ppph[0];
 	skb->data[1] = ppph[1];
 
- 	l2tp_xmit_skb(session, skb, hdr_len);
+ 	l2tp_xmit_skb(session, skb, session->header_len);
 
 	sock_put(sk_tun);
 	sock_put(sk);
@@ -646,6 +627,7 @@ static int pppol2tp_connect(struct socke
 {
 	struct sock *sk = sock->sk;
 	struct sockaddr_pppol2tp *sp = (struct sockaddr_pppol2tp *) uservaddr;
+	struct sockaddr_pppol2tpv3 *sp3 = (struct sockaddr_pppol2tpv3 *) uservaddr;
 	struct pppox_sock *po = pppox_sk(sk);
 	struct l2tp_session *session = NULL;
 	struct l2tp_tunnel *tunnel;
@@ -653,6 +635,10 @@ static int pppol2tp_connect(struct socke
 	struct dst_entry *dst;
 	struct l2tp_session_cfg cfg = { 0, };
 	int error = 0;
+	u32 tunnel_id, peer_tunnel_id;
+	u32 session_id, peer_session_id;
+	int ver = 2;
+	int fd;
 
 	lock_sock(sk);
 
@@ -670,22 +656,41 @@ static int pppol2tp_connect(struct socke
 	if (sk->sk_user_data)
 		goto end; /* socket is already attached */
 
-	/* Don't bind if s_tunnel is 0 */
+	/* Get params from socket address. Handle L2TPv2 and L2TPv3 */
+	if (sockaddr_len == sizeof(struct sockaddr_pppol2tp)) {
+		fd = sp->pppol2tp.fd;
+		tunnel_id = sp->pppol2tp.s_tunnel;
+		peer_tunnel_id = sp->pppol2tp.d_tunnel;
+		session_id = sp->pppol2tp.s_session;
+		peer_session_id = sp->pppol2tp.d_session;
+	} else if (sockaddr_len == sizeof(struct sockaddr_pppol2tpv3)) {
+		ver = 3;
+		fd = sp3->pppol2tp.fd;
+		tunnel_id = sp3->pppol2tp.s_tunnel;
+		peer_tunnel_id = sp3->pppol2tp.d_tunnel;
+		session_id = sp3->pppol2tp.s_session;
+		peer_session_id = sp3->pppol2tp.d_session;
+	} else {
+		error = -EINVAL;
+		goto end; /* bad socket address */
+	}
+
+	/* Don't bind if tunnel_id is 0 */
 	error = -EINVAL;
-	if (sp->pppol2tp.s_tunnel == 0)
+	if (tunnel_id == 0)
 		goto end;
 
-	/* Special case: create tunnel context if s_session and
-	 * d_session is 0. Otherwise look up tunnel using supplied
+	/* Special case: create tunnel context if session_id and
+	 * peer_session_id is 0. Otherwise look up tunnel using supplied
 	 * tunnel id.
 	 */
-	if ((sp->pppol2tp.s_session == 0) && (sp->pppol2tp.d_session == 0)) {
+	if ((session_id == 0) && (peer_session_id == 0)) {
 		struct l2tp_tunnel_cfg tcfg = { 0, };
-		error = l2tp_tunnel_create(sp->pppol2tp.fd, 2, sp->pppol2tp.s_tunnel, sp->pppol2tp.d_tunnel, &tcfg, &tunnel);
+		error = l2tp_tunnel_create(fd, ver, tunnel_id, peer_tunnel_id, &tcfg, &tunnel);
 		if (error < 0)
 			goto end;
 	} else {
-		tunnel = l2tp_tunnel_find(sp->pppol2tp.s_tunnel);
+		tunnel = l2tp_tunnel_find(tunnel_id);
 
 		/* Error if we can't find the tunnel */
 		error = -ENOENT;
@@ -702,19 +707,20 @@ static int pppol2tp_connect(struct socke
 
 	/* Check that this session doesn't already exist */
 	error = -EEXIST;
-	session = l2tp_session_find(tunnel, sp->pppol2tp.s_session);
+	session = l2tp_session_find(tunnel, session_id);
 	if (session != NULL)
 		goto end;
 
-	/* Default MTU must allow space for UDP/L2TP/PPP
-	 * headers.
-	 */
-	cfg.mtu = cfg.mru = 1500 - PPPOL2TP_HEADER_OVERHEAD;
+	/* Default MTU values. */
+	if (cfg.mtu == 0)
+		cfg.mtu = 1500 - PPPOL2TP_HEADER_OVERHEAD;
+	if (cfg.mru == 0)
+		cfg.mru = cfg.mtu;
 
 	/* Allocate and initialize a new session context. */
 	session = l2tp_session_create(sizeof(struct pppol2tp_session),
-				      tunnel, sp->pppol2tp.s_session,
-				      sp->pppol2tp.d_session, &cfg);
+				      tunnel, session_id,
+				      peer_session_id, &cfg);
 	if (session == NULL) {
 		error = -ENOMEM;
 		goto end;
@@ -779,8 +785,6 @@ static int pppol2tp_connect(struct socke
 out_no_ppp:
 	/* This is how we get the session context from the socket. */
 	sk->sk_user_data = session;
-
-	l2tp_tunnel_inc_refcount(tunnel);
 	sk->sk_state = PPPOX_CONNECTED;
 	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
 	       "%s: created\n", session->name);
@@ -790,10 +794,6 @@ end_put_tun:
 end:
 	release_sock(sk);
 
-	if (error != 0)
-		printk(KERN_WARNING "sess %hu/%hu: connect failed: %d\n",
-		       sp->pppol2tp.d_tunnel, sp->pppol2tp.d_session, error);
-
 	return error;
 }
 
@@ -802,8 +802,7 @@ end:
 static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 			    int *usockaddr_len, int peer)
 {
-	int len = sizeof(struct sockaddr_pppol2tp);
-	struct sockaddr_pppol2tp sp;
+	int len = 0;
 	int error = 0;
 	struct l2tp_session *session;
 	struct l2tp_tunnel *tunnel;
@@ -826,28 +825,50 @@ static int pppol2tp_getname(struct socke
 	tunnel = l2tp_sock_to_tunnel(pls->tunnel_sock);
 	if (tunnel == NULL) {
 		error = -EBADF;
-		goto end;
+		goto end_put_sess;
 	}
 
-	memset(&sp, 0, len);
-	sp.sa_family	= AF_PPPOX;
-	sp.sa_protocol	= PX_PROTO_OL2TP;
-	sp.pppol2tp.fd  = tunnel->fd;
-	sp.pppol2tp.pid = pls->owner;
-	sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
-	sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
-	sp.pppol2tp.s_session = session->session_id;
-	sp.pppol2tp.d_session = session->peer_session_id;
 	inet = inet_sk(sk);
-	sp.pppol2tp.addr.sin_family = AF_INET;
-	sp.pppol2tp.addr.sin_port = inet->dport;
-	sp.pppol2tp.addr.sin_addr.s_addr = inet->daddr;
 
-	memcpy(uaddr, &sp, len);
+	if (tunnel->version == 2) {
+		struct sockaddr_pppol2tp sp;
+		len = sizeof(sp);
+		memset(&sp, 0, len);
+		sp.sa_family	= AF_PPPOX;
+		sp.sa_protocol	= PX_PROTO_OL2TP;
+		sp.pppol2tp.fd  = tunnel->fd;
+		sp.pppol2tp.pid = pls->owner;
+		sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
+		sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
+		sp.pppol2tp.s_session = session->session_id;
+		sp.pppol2tp.d_session = session->peer_session_id;
+		sp.pppol2tp.addr.sin_family = AF_INET;
+		sp.pppol2tp.addr.sin_port = inet->dport;
+		sp.pppol2tp.addr.sin_addr.s_addr = inet->daddr;
+		memcpy(uaddr, &sp, len);
+	} else if (tunnel->version == 3) {
+		struct sockaddr_pppol2tpv3 sp;
+		len = sizeof(sp);
+		memset(&sp, 0, len);
+		sp.sa_family	= AF_PPPOX;
+		sp.sa_protocol	= PX_PROTO_OL2TP;
+		sp.pppol2tp.fd  = tunnel->fd;
+		sp.pppol2tp.pid = pls->owner;
+		sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
+		sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
+		sp.pppol2tp.s_session = session->session_id;
+		sp.pppol2tp.d_session = session->peer_session_id;
+		sp.pppol2tp.addr.sin_family = AF_INET;
+		sp.pppol2tp.addr.sin_port = inet->dport;
+		sp.pppol2tp.addr.sin_addr.s_addr = inet->daddr;
+		memcpy(uaddr, &sp, len);
+	}
 
 	*usockaddr_len = len;
 
-	sock_put(sock->sk);
+	sock_put(pls->tunnel_sock);
+end_put_sess:
+	sock_put(sk);
 	error = 0;
 
 end:
Index: net-next-2.6-l2tpv3-2/include/linux/if_pppol2tp.h
===================================================================
--- net-next-2.6-l2tpv3-2.orig/include/linux/if_pppol2tp.h
+++ net-next-2.6-l2tpv3-2/include/linux/if_pppol2tp.h
@@ -2,7 +2,7 @@
  * Linux PPP over L2TP (PPPoL2TP) Socket Implementation (RFC 2661)
  *
  * This file supplies definitions required by the PPP over L2TP driver
- * (pppol2tp.c).  All version information wrt this file is located in pppol2tp.c
+ * (l2tp_eth.c).  All version information wrt this file is located in l2tp_eth.c
  *
  * License:
  *		This program is free software; you can redistribute it and/or
@@ -36,6 +36,20 @@ struct pppol2tp_addr
 	__u16 d_tunnel, d_session;	/* For sending outgoing packets */
 };
 
+/* The L2TPv3 protocol changes tunnel and session ids from 16 to 32
+ * bits. So we need a different sockaddr structure.
+ */
+struct pppol2tpv3_addr {
+	pid_t	pid;			/* pid that owns the fd.
+					 * 0 => current */
+	int	fd;			/* FD of UDP or IP socket to use */
+
+	struct sockaddr_in addr;	/* IP address and port to send to */
+
+	__u32 s_tunnel, s_session;	/* For matching incoming packets */
+	__u32 d_tunnel, d_session;	/* For sending outgoing packets */
+};
+
 /* Socket options:
  * DEBUG	- bitmask of debug message categories
  * SENDSEQ	- 0 => don't send packets with sequence numbers
Index: net-next-2.6-l2tpv3-2/include/linux/if_pppox.h
===================================================================
--- net-next-2.6-l2tpv3-2.orig/include/linux/if_pppox.h
+++ net-next-2.6-l2tpv3-2/include/linux/if_pppox.h
@@ -72,6 +72,15 @@ struct sockaddr_pppol2tp {
 	struct pppol2tp_addr pppol2tp;
 }__attribute__ ((packed));
 
+/* The L2TPv3 protocol changes tunnel and session ids from 16 to 32
+ * bits. So we need a different sockaddr structure.
+ */
+struct sockaddr_pppol2tpv3 {
+	sa_family_t     sa_family;      /* address family, AF_PPPOX */
+	unsigned int    sa_protocol;    /* protocol identifier */
+	struct pppol2tpv3_addr pppol2tp;
+} __attribute__ ((packed));
+
 /*********************************************************************
  *
  * ioctl interface for defining forwarding of connections
--
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