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Commit 38fbbc9c authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'l2tp-fix-races-with-ipv4-mapped-ipv6-addresses' 



Paolo Abeni says:

====================
l2tp: fix races with ipv4-mapped ipv6 addresses

The syzbot reported an l2tp oops that uncovered some races in the l2tp xmit
path and a partially related issue in the generic ipv6 code.

We need to address them separately.

v1 -> v2:
 - add missing fixes tag in patch 1
 - fix several issues in patch 2

v2 -> v3:
 - dropped some unneeded chunks in patch 2
====================

Reviewed-by: default avatarGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents b7475948 b954f940

net/ipv6/datagram.c

+14 −7
Original line number Diff line number Diff line
@@ -146,10 +146,12 @@ int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, 
	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;

	struct inet_sock	*inet = inet_sk(sk);

	struct ipv6_pinfo	*np = inet6_sk(sk);

	struct in6_addr		*daddr;

	struct in6_addr		*daddr, old_daddr;

	__be32			fl6_flowlabel = 0;

	__be32			old_fl6_flowlabel;

	__be32			old_dport;

	int			addr_type;

	int			err;

	__be32			fl6_flowlabel = 0;



	if (usin->sin6_family == AF_INET) {

		if (__ipv6_only_sock(sk))
@@ -238,9 +240,13 @@ int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, 
		}

	}



	/* save the current peer information before updating it */

	old_daddr = sk->sk_v6_daddr;

	old_fl6_flowlabel = np->flow_label;

	old_dport = inet->inet_dport;



	sk->sk_v6_daddr = *daddr;

	np->flow_label = fl6_flowlabel;



	inet->inet_dport = usin->sin6_port;



	/*
@@ -250,11 +256,12 @@ int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, 


	err = ip6_datagram_dst_update(sk, true);

	if (err) {

		/* Reset daddr and dport so that udp_v6_early_demux()

		 * fails to find this socket

		/* Restore the socket peer info, to keep it consistent with

		 * the old socket state

		 */

		memset(&sk->sk_v6_daddr, 0, sizeof(sk->sk_v6_daddr));

		inet->inet_dport = 0;

		sk->sk_v6_daddr = old_daddr;

		np->flow_label = old_fl6_flowlabel;

		inet->inet_dport = old_dport;

		goto out;

	}

net/l2tp/l2tp_core.c

+18 −20
Original line number Diff line number Diff line
@@ -111,6 +111,13 @@ struct l2tp_net { 
	spinlock_t l2tp_session_hlist_lock;

};



#if IS_ENABLED(CONFIG_IPV6)

static bool l2tp_sk_is_v6(struct sock *sk)

{

	return sk->sk_family == PF_INET6 &&

	       !ipv6_addr_v4mapped(&sk->sk_v6_daddr);

}

#endif



static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)

{
@@ -1049,7 +1056,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 
	/* Queue the packet to IP for output */

	skb->ignore_df = 1;

#if IS_ENABLED(CONFIG_IPV6)

	if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)

	if (l2tp_sk_is_v6(tunnel->sock))

		error = inet6_csk_xmit(tunnel->sock, skb, NULL);

	else

#endif
@@ -1112,6 +1119,15 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len 
		goto out_unlock;

	}



	/* The user-space may change the connection status for the user-space

	 * provided socket at run time: we must check it under the socket lock

	 */

	if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) {

		kfree_skb(skb);

		ret = NET_XMIT_DROP;

		goto out_unlock;

	}



	/* Get routing info from the tunnel socket */

	skb_dst_drop(skb);

	skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
@@ -1131,7 +1147,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len 


		/* Calculate UDP checksum if configured to do so */

#if IS_ENABLED(CONFIG_IPV6)

		if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)

		if (l2tp_sk_is_v6(sk))

			udp6_set_csum(udp_get_no_check6_tx(sk),

				      skb, &inet6_sk(sk)->saddr,

				      &sk->sk_v6_daddr, udp_len);
@@ -1511,24 +1527,6 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 
	if (cfg != NULL)

		tunnel->debug = cfg->debug;



#if IS_ENABLED(CONFIG_IPV6)

	if (sk->sk_family == PF_INET6) {

		struct ipv6_pinfo *np = inet6_sk(sk);



		if (ipv6_addr_v4mapped(&np->saddr) &&

		    ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {

			struct inet_sock *inet = inet_sk(sk);



			tunnel->v4mapped = true;

			inet->inet_saddr = np->saddr.s6_addr32[3];

			inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];

			inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];

		} else {

			tunnel->v4mapped = false;

		}

	}

#endif



	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */

	tunnel->encap = encap;

	if (encap == L2TP_ENCAPTYPE_UDP) {

net/l2tp/l2tp_core.h

+0 −3
Original line number Diff line number Diff line
@@ -188,9 +188,6 @@ struct l2tp_tunnel { 
	struct sock		*sock;		/* Parent socket */

	int			fd;		/* Parent fd, if tunnel socket

						 * was created by userspace */

#if IS_ENABLED(CONFIG_IPV6)

	bool			v4mapped;

#endif



	struct work_struct	del_work;