[net-next RFC 4/4] bindtosubnet: UPD implementation

[Gilberto Bertin]

Signed-off-by: Gilberto Bertin <gilberto.ber...@gmail.com>
---
 net/ipv4/udp.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c438908..0e78fc4 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -132,6 +132,22 @@ EXPORT_SYMBOL(udp_memory_allocated);
 #define MAX_UDP_PORTS 65536
 #define PORTS_PER_CHAIN (MAX_UDP_PORTS / UDP_HTABLE_SIZE_MIN)
 
+static inline int udp_csk_bind_subnet_conflict(const struct sock *sk,
+                                              const struct sock *sk2)
+{
+       __be32 mask;
+
+       if (sk->sk_bind_to_subnet && sk2->sk_bind_to_subnet) {
+               mask = inet_make_mask(min(sk->sk_bind_subnet4.plen,
+                                         sk2->sk_bind_subnet4.plen));
+
+               return (sk->sk_bind_subnet4.net & mask) ==
+                      (sk2->sk_bind_subnet4.net & mask);
+       }
+
+       return 0;
+}
+
 static int udp_lib_lport_inuse(struct net *net, __u16 num,
                               const struct udp_hslot *hslot,
                               unsigned long *bitmap,
@@ -151,6 +167,7 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num,
                    (!sk2->sk_reuse || !sk->sk_reuse) &&
                    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
                     sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
+                    udp_csk_bind_subnet_conflict(sk, sk2) &&
                    (!sk2->sk_reuseport || !sk->sk_reuseport ||
                     !uid_eq(uid, sock_i_uid(sk2))) &&
                    saddr_comp(sk, sk2)) {
@@ -185,6 +202,7 @@ static int udp_lib_lport_inuse2(struct net *net, __u16 num,
                    (!sk2->sk_reuse || !sk->sk_reuse) &&
                    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if ||
                     sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
+                    udp_csk_bind_subnet_conflict(sk, sk2) &&
                    (!sk2->sk_reuseport || !sk->sk_reuseport ||
                     !uid_eq(uid, sock_i_uid(sk2))) &&
                    saddr_comp(sk, sk2)) {
@@ -374,6 +392,15 @@ static inline int compute_score(struct sock *sk, struct 
net *net,
                        return -1;
                score += 4;
        }
+
+       if (sk->sk_bind_to_subnet) {
+               __be32 mask = inet_make_mask(sk->sk_bind_subnet4.plen);
+
+               if ((sk->sk_bind_subnet4.net & mask) != (daddr & mask))
+                       return -1;
+               score += 4;
+       }
+
        if (sk->sk_incoming_cpu == raw_smp_processor_id())
                score++;
        return score;
@@ -419,6 +446,14 @@ static inline int compute_score2(struct sock *sk, struct 
net *net,
                score += 4;
        }
 
+       if (sk->sk_bind_to_subnet) {
+               __be32 mask = inet_make_mask(sk->sk_bind_subnet4.plen);
+
+               if ((sk->sk_bind_subnet4.net & mask) != (daddr & mask))
+                       return -1;
+               score += 4;
+       }
+
        if (sk->sk_incoming_cpu == raw_smp_processor_id())
                score++;
 
-- 
2.7.1