Commit 3e1bc8bf authored Jun 13, 2018 by Guillaume Nault Committed by David S. Miller Jun 14, 2018

l2tp: prevent pppol2tp_connect() from creating kernel sockets



If 'fd' is negative, l2tp_tunnel_create() creates a tunnel socket using
the configuration passed in 'tcfg'. Currently, pppol2tp_connect() sets
the relevant fields to zero, tricking l2tp_tunnel_create() into setting
up an unusable kernel socket.

We can't set 'tcfg' with the required fields because there's no way to
get them from the current connect() parameters. So let's restrict
kernel sockets creation to the netlink API, which is the original use
case.

Fixes: 789a4a2c ("l2tp: Add support for static unmanaged L2TPv3 tunnels")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 7ac6ab1f

net/l2tp/l2tp_ppp.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -701,6 +701,15 @@ static int pppol2tp_connect(struct socket sock, struct sockaddr uservaddr,
		.encap = L2TP_ENCAPTYPE_UDP,
		.debug = 0,
		};

		/* Prevent l2tp_tunnel_register() from trying to set up
		* a kernel socket.
		*/
		if (fd < 0) {
		error = -EBADF;
		goto end;
		}

		error = l2tp_tunnel_create(sock_net(sk), fd, ver, tunnel_id, peer_tunnel_id, &tcfg, &tunnel);
		if (error < 0)
		goto end;

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