[PATCH AUTOSEL 5.1 31/95] bpf: udp: Avoid calling reuseport's bpf_prog from udp_gro

[Sasha Levin]

From: Martin KaFai Lau <kafai@xxxxxx>

[ Upstream commit 257a525fe2e49584842c504a92c27097407f778f ]

When the commit a6024562ffd7 ("udp: Add GRO functions to UDP socket")
added udp[46]_lib_lookup_skb to the udp_gro code path, it broke
the reuseport_select_sock() assumption that skb->data is pointing
to the transport header.

This patch follows an earlier __udp6_lib_err() fix by
passing a NULL skb to avoid calling the reuseport's bpf_prog.

Fixes: a6024562ffd7 ("udp: Add GRO functions to UDP socket")
Cc: Tom Herbert <tom@xxxxxxxxxxxxxxx>
Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/ipv4/udp.c | 6 +++++-
 net/ipv6/udp.c | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 3b179ce6170f..2274d8ad8afa 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -503,7 +503,11 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
 struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
 				 __be16 sport, __be16 dport)
 {
-	return __udp4_lib_lookup_skb(skb, sport, dport, &udp_table);
+	const struct iphdr *iph = ip_hdr(skb);
+
+	return __udp4_lib_lookup(dev_net(skb->dev), iph->saddr, sport,
+				 iph->daddr, dport, inet_iif(skb),
+				 inet_sdif(skb), &udp_table, NULL);
 }
 EXPORT_SYMBOL_GPL(udp4_lib_lookup_skb);
 
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 767583c12bf2..874ee2954f53 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -242,7 +242,7 @@ struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
 
 	return __udp6_lib_lookup(dev_net(skb->dev), &iph->saddr, sport,
 				 &iph->daddr, dport, inet6_iif(skb),
-				 inet6_sdif(skb), &udp_table, skb);
+				 inet6_sdif(skb), &udp_table, NULL);
 }
 EXPORT_SYMBOL_GPL(udp6_lib_lookup_skb);
 
-- 
2.20.1