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[bpf-next,1/2] udp: Don't discard reuseport selection when group has connections

Message ID 20200722161720.940831-2-jakub@cloudflare.com
State Accepted
Delegated to: BPF Maintainers
Headers show
Series Fix BPF socket lookup with reuseport groups with connections | expand

Commit Message

Jakub Sitnicki July 22, 2020, 4:17 p.m. UTC 
When BPF socket lookup prog selects a socket that belongs to a reuseport
group, and the reuseport group has connected sockets in it, the socket
selected by reuseport will be discarded, and socket returned by BPF socket
lookup will be used instead.

Modify this behavior so that the socket selected by reuseport running after
BPF socket lookup always gets used. Ignore the fact that the reuseport
group might have connections because it is only relevant when scoring
sockets during regular hashtable-based lookup.

Fixes: 72f7e9440e9b ("udp: Run SK_LOOKUP BPF program on socket lookup")
Fixes: 6d4201b1386b ("udp6: Run SK_LOOKUP BPF program on socket lookup")
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
---
 net/ipv4/udp.c | 5 +----
 net/ipv6/udp.c | 5 +----
 2 files changed, 2 insertions(+), 8 deletions(-)
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Patch

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b5231ab350e0..487740d0088c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -421,9 +421,6 @@  static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
 		hash = udp_ehashfn(net, daddr, hnum, saddr, sport);
 		reuse_sk = reuseport_select_sock(sk, hash, skb,
 						 sizeof(struct udphdr));
-		/* Fall back to scoring if group has connections */
-		if (reuseport_has_conns(sk, false))
-			return NULL;
 	}
 	return reuse_sk;
 }
@@ -447,7 +444,7 @@  static struct sock *udp4_lib_lookup2(struct net *net,
 		if (score > badness) {
 			result = lookup_reuseport(net, sk, skb,
 						  saddr, sport, daddr, hnum);
-			if (result)
+			if (result && !reuseport_has_conns(sk, false))
 				return result;
 
 			badness = score;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index ff8be202726a..8fd8eb04994c 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -155,9 +155,6 @@  static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
 		hash = udp6_ehashfn(net, daddr, hnum, saddr, sport);
 		reuse_sk = reuseport_select_sock(sk, hash, skb,
 						 sizeof(struct udphdr));
-		/* Fall back to scoring if group has connections */
-		if (reuseport_has_conns(sk, false))
-			return NULL;
 	}
 	return reuse_sk;
 }
@@ -180,7 +177,7 @@  static struct sock *udp6_lib_lookup2(struct net *net,
 		if (score > badness) {
 			result = lookup_reuseport(net, sk, skb,
 						  saddr, sport, daddr, hnum);
-			if (result)
+			if (result && !reuseport_has_conns(sk, false))
 				return result;
 
 			result = sk;