Same as for udp4, let BPF program override the socket lookup result, by
selecting a receiving socket of its choice or failing the lookup, if no
connected UDP socket matched packet 4-tuple.
Suggested-by: Marek Majkowski <ma...@cloudflare.com>
Signed-off-by: Jakub Sitnicki <ja...@cloudflare.com>
---
Notes:
v3:
- Use a static_key to minimize the hook overhead when not used. (Alexei)
- Adapt for running an array of attached programs. (Alexei)
- Adapt for optionally skipping reuseport selection. (Martin)
net/ipv6/udp.c | 60 ++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 51 insertions(+), 9 deletions(-)
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 65b843e7acde..c4338cfe7a8c 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -190,6 +190,31 @@ static struct sock *udp6_lib_lookup2(struct net *net,
return result;
}
+static inline struct sock *udp6_lookup_run_bpf(struct net *net,
+ struct udp_table *udptable,
+ struct sk_buff *skb,
+ const struct in6_addr *saddr,
+ __be16 sport,
+ const struct in6_addr *daddr,
+ u16 hnum)
+{
+ struct sock *sk, *reuse_sk;
+ bool do_reuseport;
+
+ if (udptable != &udp_table)
+ return NULL; /* only UDP is supported */
+
+ do_reuseport = bpf_sk_lookup_run_v6(net, IPPROTO_UDP,
+ saddr, sport, daddr, hnum, &sk);
+ if (do_reuseport) {
+ reuse_sk = lookup_reuseport(net, sk, skb,
+ saddr, sport, daddr, hnum);
+ if (reuse_sk)
+ sk = reuse_sk;
+ }
+ return sk;
+}
+
/* rcu_read_lock() must be held */
struct sock *__udp6_lib_lookup(struct net *net,
const struct in6_addr *saddr, __be16 sport,
@@ -200,25 +225,42 @@ struct sock *__udp6_lib_lookup(struct net *net,
unsigned short hnum = ntohs(dport);
unsigned int hash2, slot2;
struct udp_hslot *hslot2;
- struct sock *result;
+ struct sock *result, *sk;
hash2 = ipv6_portaddr_hash(net, daddr, hnum);
slot2 = hash2 & udptable->mask;
hslot2 = &udptable->hash2[slot2];
+ /* Lookup connected or non-wildcard sockets */
result = udp6_lib_lookup2(net, saddr, sport,
daddr, hnum, dif, sdif,
hslot2, skb);
- if (!result) {
- hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
- slot2 = hash2 & udptable->mask;
+ if (!IS_ERR_OR_NULL(result) && result->sk_state == TCP_ESTABLISHED)
+ goto done;
+
+ /* Lookup redirect from BPF */
+ if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
+ sk = udp6_lookup_run_bpf(net, udptable, skb,
+ saddr, sport, daddr, hnum);
+ if (sk) {
+ result = sk;
+ goto done;
+ }
+ }
- hslot2 = &udptable->hash2[slot2];
+ /* Got non-wildcard socket or error on first lookup */
+ if (result)
+ goto done;
- result = udp6_lib_lookup2(net, saddr, sport,
- &in6addr_any, hnum, dif, sdif,
- hslot2, skb);
- }
+ /* Lookup wildcard sockets */
+ hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
+ slot2 = hash2 & udptable->mask;
+ hslot2 = &udptable->hash2[slot2];
+
+ result = udp6_lib_lookup2(net, saddr, sport,
+ &in6addr_any, hnum, dif, sdif,
+ hslot2, skb);
+done:
if (IS_ERR(result))
return NULL;
return result;
--
2.25.4
