net: inet: Support UID-based routing in IP protocols.

- Use the UID in routing lookups made by protocol connect() and
  sendmsg() functions.
- Make sure that routing lookups triggered by incoming packets
  (e.g., Path MTU discovery) take the UID of the socket into
  account.
- For packets not associated with a userspace socket, (e.g., ping
  replies) use UID 0 inside the user namespace corresponding to
  the network namespace the socket belongs to. This allows
  all namespaces to apply routing and iptables rules to
  kernel-originated traffic in that namespaces by matching UID 0.
  This is better than using the UID of the kernel socket that is
  sending the traffic, because the UID of kernel sockets created
  at namespace creation time (e.g., the per-processor ICMP and
  TCP sockets) is the UID of the user that created the socket,
  which might not be mapped in the namespace.

Tested: compiles allnoconfig, allyesconfig, allmodconfig
Tested: https://android-review.googlesource.com/253302
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 4 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index fdb9c87..6aa014e 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1405,7 +1405,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 }
 
 void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
-		     int oif, u32 mark)
+		     int oif, u32 mark, kuid_t uid)
 {
 	const struct ipv6hdr *iph = (struct ipv6hdr *) skb->data;
 	struct dst_entry *dst;
@@ -1417,6 +1417,7 @@ void ip6_update_pmtu(struct sk_buff *skb, struct net *net, __be32 mtu,
 	fl6.daddr = iph->daddr;
 	fl6.saddr = iph->saddr;
 	fl6.flowlabel = ip6_flowinfo(iph);
+	fl6.flowi6_uid = uid;
 
 	dst = ip6_route_output(net, NULL, &fl6);
 	if (!dst->error)
@@ -1430,7 +1431,7 @@ void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, __be32 mtu)
 	struct dst_entry *dst;
 
 	ip6_update_pmtu(skb, sock_net(sk), mtu,
-			sk->sk_bound_dev_if, sk->sk_mark);
+			sk->sk_bound_dev_if, sk->sk_mark, sk->sk_uid);
 
 	dst = __sk_dst_get(sk);
 	if (!dst || !dst->obsolete ||
@@ -1522,7 +1523,8 @@ static struct dst_entry *ip6_route_redirect(struct net *net,
 				flags, __ip6_route_redirect);
 }
 
-void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark)
+void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark,
+		  kuid_t uid)
 {
 	const struct ipv6hdr *iph = (struct ipv6hdr *) skb->data;
 	struct dst_entry *dst;
@@ -1535,6 +1537,7 @@ void ip6_redirect(struct sk_buff *skb, struct net *net, int oif, u32 mark)
 	fl6.daddr = iph->daddr;
 	fl6.saddr = iph->saddr;
 	fl6.flowlabel = ip6_flowinfo(iph);
+	fl6.flowi6_uid = uid;
 
 	dst = ip6_route_redirect(net, &fl6, &ipv6_hdr(skb)->saddr);
 	rt6_do_redirect(dst, NULL, skb);
@@ -1556,6 +1559,7 @@ void ip6_redirect_no_header(struct sk_buff *skb, struct net *net, int oif,
 	fl6.flowi6_mark = mark;
 	fl6.daddr = msg->dest;
 	fl6.saddr = iph->daddr;
+	fl6.flowi6_uid = sock_net_uid(net, NULL);
 
 	dst = ip6_route_redirect(net, &fl6, &iph->saddr);
 	rt6_do_redirect(dst, NULL, skb);
@@ -1564,7 +1568,8 @@ void ip6_redirect_no_header(struct sk_buff *skb, struct net *net, int oif,
 
 void ip6_sk_redirect(struct sk_buff *skb, struct sock *sk)
 {
-	ip6_redirect(skb, sock_net(sk), sk->sk_bound_dev_if, sk->sk_mark);
+	ip6_redirect(skb, sock_net(sk), sk->sk_bound_dev_if, sk->sk_mark,
+		     sk->sk_uid);
 }
 EXPORT_SYMBOL_GPL(ip6_sk_redirect);