l2tp: pppol2tp_connect() handles ipv6 sockaddr variants

Userspace uses connect() to associate a pppol2tp socket with a tunnel
socket. This needs to allow the caller to supply the new IPv6
sockaddr_pppol2tp structures if IPv6 is used.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 8 deletions

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 27b9dec9d254..9f2c421aa307 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -628,7 +628,6 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 {
         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;
@@ -657,7 +656,13 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
         if (sk->sk_user_data)
                 goto end; /* socket is already attached */
 
-        /* Get params from socket address. Handle L2TPv2 and L2TPv3 */
+        /* Get params from socket address. Handle L2TPv2 and L2TPv3.
+         * This is nasty because there are different sockaddr_pppol2tp
+         * structs for L2TPv2, L2TPv3, over IPv4 and IPv6. We use
+         * the sockaddr size to determine which structure the caller
+         * is using.
+         */
+        peer_tunnel_id = 0;
         if (sockaddr_len == sizeof(struct sockaddr_pppol2tp)) {
                 fd = sp->pppol2tp.fd;
                 tunnel_id = sp->pppol2tp.s_tunnel;
@@ -665,12 +670,31 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
                 session_id = sp->pppol2tp.s_session;
                 peer_session_id = sp->pppol2tp.d_session;
         } else if (sockaddr_len == sizeof(struct sockaddr_pppol2tpv3)) {
+                struct sockaddr_pppol2tpv3 *sp3 =
+                        (struct sockaddr_pppol2tpv3 *) sp;
                 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 if (sockaddr_len == sizeof(struct sockaddr_pppol2tpin6)) {
+                struct sockaddr_pppol2tpin6 *sp6 =
+                        (struct sockaddr_pppol2tpin6 *) sp;
+                fd = sp6->pppol2tp.fd;
+                tunnel_id = sp6->pppol2tp.s_tunnel;
+                peer_tunnel_id = sp6->pppol2tp.d_tunnel;
+                session_id = sp6->pppol2tp.s_session;
+                peer_session_id = sp6->pppol2tp.d_session;
+        } else if (sockaddr_len == sizeof(struct sockaddr_pppol2tpv3in6)) {
+                struct sockaddr_pppol2tpv3in6 *sp6 =
+                        (struct sockaddr_pppol2tpv3in6 *) sp;
+                ver = 3;
+                fd = sp6->pppol2tp.fd;
+                tunnel_id = sp6->pppol2tp.s_tunnel;
+                peer_tunnel_id = sp6->pppol2tp.d_tunnel;
+                session_id = sp6->pppol2tp.s_session;
+                peer_session_id = sp6->pppol2tp.d_session;
         } else {
                 error = -EINVAL;
                 goto end; /* bad socket address */
@@ -711,12 +735,8 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
         if (tunnel->recv_payload_hook == NULL)
                 tunnel->recv_payload_hook = pppol2tp_recv_payload_hook;
 
-        if (tunnel->peer_tunnel_id == 0) {
-                if (ver == 2)
-                        tunnel->peer_tunnel_id = sp->pppol2tp.d_tunnel;
-                else
-                        tunnel->peer_tunnel_id = sp3->pppol2tp.d_tunnel;
-        }
+        if (tunnel->peer_tunnel_id == 0)
+                tunnel->peer_tunnel_id = peer_tunnel_id;
 
         /* Create session if it doesn't already exist. We handle the
          * case where a session was previously created by the netlink