net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup

BugLink: https://bugs.launchpad.net/bugs/1876982

ipv6_stub uses the ip6_dst_lookup function to allow other modules to
perform IPv6 lookups. However, this function skips the XFRM layer
entirely.

All users of ipv6_stub->ip6_dst_lookup use ip_route_output_flow (via the
ip_route_output_key and ip_route_output helpers) for their IPv4 lookups,
which calls xfrm_lookup_route(). This patch fixes this inconsistent
behavior by switching the stub to ip6_dst_lookup_flow, which also calls
xfrm_lookup_route().

This requires some changes in all the callers, as these two functions
take different arguments and have different return types.

Fixes: 5f81bd2e ("ipv6: export a stub for IPv6 symbols used by vxlan")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
(backported from commit 6c8991f4)
CVE-2020-1749
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Sultan Alsawaf <sultan.alsawaf@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/infiniband/core/addr.c

@@ -293,9 +293,9 @@ static int addr6_resolve(struct sockaddr_in6 *src_in,
 	fl6.saddr = src_in->sin6_addr;
 	fl6.flowi6_oif = addr->bound_dev_if;
 
-	ret = ipv6_stub->ipv6_dst_lookup(addr->net, NULL, &dst, &fl6);
-	if (ret < 0)
-		goto put;
+	dst = ipv6_stub->ipv6_dst_lookup_flow(addr->net, NULL, &fl6, NULL);
+	if (IS_ERR(dst))
+		return PTR_ERR(dst);
 
 	if (ipv6_addr_any(&fl6.saddr)) {
 		ret = ipv6_dev_get_saddr(addr->net, ip6_dst_idev(dst)->dev,

drivers/net/geneve.c

@@ -820,7 +820,9 @@ static struct dst_entry *geneve_get_v6_dst(struct sk_buff *skb,
 		fl6->daddr = geneve->remote.sin6.sin6_addr;
 	}
 
-	if (ipv6_stub->ipv6_dst_lookup(geneve->net, gs6->sock->sk, &dst, fl6)) {
+	dst = ipv6_stub->ipv6_dst_lookup_flow(geneve->net, gs6->sock->sk, fl6,
+					      NULL);
+	if (IS_ERR(dst)) {
 		netdev_dbg(dev, "no route to %pI6\n", &fl6->daddr);
 		return ERR_PTR(-ENETUNREACH);
 	}

drivers/net/vxlan.c

@@ -2026,7 +2026,6 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan,
 {
 	struct dst_entry *ndst;
 	struct flowi6 fl6;
-	int err;
 
 	memset(&fl6, 0, sizeof(fl6));
 	fl6.flowi6_oif = oif;
@@ -2035,11 +2034,11 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan,
 	fl6.flowi6_mark = skb->mark;
 	fl6.flowi6_proto = IPPROTO_UDP;
 
-	err = ipv6_stub->ipv6_dst_lookup(vxlan->net,
-					 vxlan->vn6_sock->sock->sk,
-					 &ndst, &fl6);
-	if (err < 0)
-		return ERR_PTR(err);
+	ndst = ipv6_stub->ipv6_dst_lookup_flow(vxlan->net,
+					       vxlan->vn6_sock->sock->sk,
+					       &fl6, NULL);
+	if (IS_ERR(ndst))
+		return ndst;
 
 	*saddr = fl6.saddr;
 	return ndst;

include/net/addrconf.h

@@ -192,8 +192,10 @@ struct ipv6_stub {
 				 const struct in6_addr *addr);
 	int (*ipv6_sock_mc_drop)(struct sock *sk, int ifindex,
 				 const struct in6_addr *addr);
-	int (*ipv6_dst_lookup)(struct net *net, struct sock *sk,
-			       struct dst_entry **dst, struct flowi6 *fl6);
+	struct dst_entry *(*ipv6_dst_lookup_flow)(struct net *net,
+						  const struct sock *sk,
+						  struct flowi6 *fl6,
+						  const struct in6_addr *final_dst);
 	void (*udpv6_encap_enable)(void);
 	void (*ndisc_send_na)(struct net_device *dev, const struct in6_addr *daddr,
 			      const struct in6_addr *solicited_addr,

net/ipv6/addrconf_core.c

@@ -107,15 +107,16 @@ int inet6addr_notifier_call_chain(unsigned long val, void *v)
 }
 EXPORT_SYMBOL(inet6addr_notifier_call_chain);
 
-static int eafnosupport_ipv6_dst_lookup(struct net *net, struct sock *u1,
-					struct dst_entry **u2,
-					struct flowi6 *u3)
+static struct dst_entry *eafnosupport_ipv6_dst_lookup_flow(struct net *net,
+							   const struct sock *sk,
+							   struct flowi6 *fl6,
+							   const struct in6_addr *final_dst)
 {
-	return -EAFNOSUPPORT;
+	return ERR_PTR(-EAFNOSUPPORT);
 }
 
 const struct ipv6_stub *ipv6_stub __read_mostly = &(struct ipv6_stub) {
-	.ipv6_dst_lookup = eafnosupport_ipv6_dst_lookup,
+	.ipv6_dst_lookup_flow = eafnosupport_ipv6_dst_lookup_flow,
 };
 EXPORT_SYMBOL_GPL(ipv6_stub);
 

net/ipv6/af_inet6.c

@@ -841,7 +841,7 @@ static struct pernet_operations inet6_net_ops = {
 static const struct ipv6_stub ipv6_stub_impl = {
 	.ipv6_sock_mc_join = ipv6_sock_mc_join,
 	.ipv6_sock_mc_drop = ipv6_sock_mc_drop,
-	.ipv6_dst_lookup = ip6_dst_lookup,
+	.ipv6_dst_lookup_flow = ip6_dst_lookup_flow,
 	.udpv6_encap_enable = udpv6_encap_enable,
 	.ndisc_send_na = ndisc_send_na,
 	.nd_tbl	= &nd_tbl,

net/mpls/af_mpls.c

@@ -472,16 +472,15 @@ static struct net_device *inet6_fib_lookup_dev(struct net *net,
 	struct net_device *dev;
 	struct dst_entry *dst;
 	struct flowi6 fl6;
-	int err;
 
 	if (!ipv6_stub)
 		return ERR_PTR(-EAFNOSUPPORT);
 
 	memset(&fl6, 0, sizeof(fl6));
 	memcpy(&fl6.daddr, addr, sizeof(struct in6_addr));
-	err = ipv6_stub->ipv6_dst_lookup(net, NULL, &dst, &fl6);
-	if (err)
-		return ERR_PTR(err);
+	dst = ipv6_stub->ipv6_dst_lookup_flow(net, NULL, &fl6, NULL);
+	if (IS_ERR(dst))
+		return ERR_CAST(dst);
 
 	dev = dst->dev;
 	dev_hold(dev);

net/tipc/udp_media.c

@@ -200,10 +200,13 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 			.saddr = src->ipv6,
 			.flowi6_proto = IPPROTO_UDP
 		};
-		err = ipv6_stub->ipv6_dst_lookup(net, ub->ubsock->sk, &ndst,
-						 &fl6);
-		if (err)
+		ndst = ipv6_stub->ipv6_dst_lookup_flow(net,
+						       ub->ubsock->sk,
+						       &fl6, NULL);
+		if (IS_ERR(ndst)) {
+			err = PTR_ERR(ndst);
 			goto tx_error;
+		}
 		ttl = ip6_dst_hoplimit(ndst);
 		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb,
 					   ndst->dev, &src->ipv6,