[PATCH net-next v3 1/4] udp: Only compare daddr/dport when sk_state == TCP_ESTABLISHED
From: Jordan Rife <hidden>
Date: 2026-03-30 21:57:11
Also in:
bpf
Subsystem:
networking [general], the rest, user datagram protocol (udp) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Willem de Bruijn
Adjust lookups and scoring to keep their results equivalent to before
even if inet_daddr+inet_dport are left intact after disconnecting a
socket (sk_state == TCP_CLOSE). sk_state == TCP_ESTABLISHED implies that
*daddr is non-zero, so remove redundant checks for that at the same
time. Note that __udp6_lib_demux_lookup already checks if sk_state ==
TCP_ESTABLISHED, so no change was needed there [1].
I could find no discernible difference in performance in
udp4_lib_lookup2 before and after the change in compute_score.
(AMD Ryzen 9 9900X)
kprobe:udp4_lib_lookup2 {
@start[cpu] = nsecs;
}
kretprobe:udp4_lib_lookup2 {
@lookup[cpu] = hist(nsecs - @start[cpu], 2);
}
BEFORE
======
@lookup[11]:
[80, 96) 1387077 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[96, 112) 364973 |@@@@@@@@@@@@@ |
[112, 128) 34261 |@ |
[128, 160) 7246 | |
[160, 192) 215 | |
[192, 224) 126 | |
AFTER
=====
@lookup[11]:
[80, 96) 1408594 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[96, 112) 340568 |@@@@@@@@@@@@ |
[112, 128) 30753 |@ |
[128, 160) 8019 | |
[160, 192) 231 | |
[192, 224) 157 | |
[1]: https://lore.kernel.org/netdev/20170623222537.130493-1-tracywwnj@gmail.com/ (local)
Signed-off-by: Jordan Rife <redacted>
---
net/ipv4/udp.c | 20 +++++++++++---------
net/ipv6/udp.c | 18 +++++++++---------
2 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b60fad393e18..d91c587c3657 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c@@ -385,16 +385,16 @@ static int compute_score(struct sock *sk, const struct net *net, score = (sk->sk_family == PF_INET) ? 2 : 1; inet = inet_sk(sk); - if (inet->inet_daddr) { + if (sk->sk_state == TCP_ESTABLISHED) { if (inet->inet_daddr != saddr) return -1; score += 4; - } - if (inet->inet_dport) { - if (inet->inet_dport != sport) - return -1; - score += 4; + if (inet->inet_dport) { + if (inet->inet_dport != sport) + return -1; + score += 4; + } } dev_match = udp_sk_bound_dev_eq(net, sk->sk_bound_dev_if,
@@ -796,8 +796,9 @@ static inline bool __udp_is_mcast_sock(struct net *net, const struct sock *sk, if (!net_eq(sock_net(sk), net) || udp_sk(sk)->udp_port_hash != hnum || - (inet->inet_daddr && inet->inet_daddr != rmt_addr) || - (inet->inet_dport != rmt_port && inet->inet_dport) || + (sk->sk_state == TCP_ESTABLISHED && + (inet->inet_daddr != rmt_addr || + (inet->inet_dport != rmt_port && inet->inet_dport))) || (inet->inet_rcv_saddr && inet->inet_rcv_saddr != loc_addr) || ipv6_only_sock(sk) || !udp_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
@@ -2854,7 +2855,8 @@ static struct sock *__udp4_lib_demux_lookup(struct net *net, ports = INET_COMBINED_PORTS(rmt_port, hnum); udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) { - if (inet_match(net, sk, acookie, ports, dif, sdif)) + if (sk->sk_state == TCP_ESTABLISHED && + inet_match(net, sk, acookie, ports, dif, sdif)) return sk; /* Only check first socket in chain */ break;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 010b909275dd..b93a9a3e7678 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c@@ -147,16 +147,16 @@ static int compute_score(struct sock *sk, const struct net *net, score = 0; inet = inet_sk(sk); - if (inet->inet_dport) { + if (sk->sk_state == TCP_ESTABLISHED) { if (inet->inet_dport != sport) return -1; score++; - } - if (!ipv6_addr_any(&sk->sk_v6_daddr)) { - if (!ipv6_addr_equal(&sk->sk_v6_daddr, saddr)) - return -1; - score++; + if (!ipv6_addr_any(&sk->sk_v6_daddr)) { + if (!ipv6_addr_equal(&sk->sk_v6_daddr, saddr)) + return -1; + score++; + } } bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
@@ -949,9 +949,9 @@ static bool __udp_v6_is_mcast_sock(struct net *net, const struct sock *sk, if (udp_sk(sk)->udp_port_hash != hnum || sk->sk_family != PF_INET6 || - (inet->inet_dport && inet->inet_dport != rmt_port) || - (!ipv6_addr_any(&sk->sk_v6_daddr) && - !ipv6_addr_equal(&sk->sk_v6_daddr, rmt_addr)) || + (sk->sk_state == TCP_ESTABLISHED && + ((inet->inet_dport && inet->inet_dport != rmt_port) || + !ipv6_addr_equal(&sk->sk_v6_daddr, rmt_addr))) || !udp_sk_bound_dev_eq(net, READ_ONCE(sk->sk_bound_dev_if), dif, sdif) || (!ipv6_addr_any(&sk->sk_v6_rcv_saddr) && !ipv6_addr_equal(&sk->sk_v6_rcv_saddr, loc_addr)))
--
2.53.0.1118.gaef5881109-goog