From: Joe Stringer <joe@wand.net.nz>
Date: Tue, 7 Apr 2020 20:35:40 -0700
Subject: bpf: Fix use of sk->sk_reuseport from sk_assign
Patch-mainline: v5.7-rc2
Git-commit: 8e368dc72e86ad1e1a612416f32d5ad22dca88bc
References: bsc#1177028
In testing, we found that for request sockets the sk->sk_reuseport field
may yet be uninitialized, which caused bpf_sk_assign() to randomly
succeed or return -ESOCKTNOSUPPORT when handling the forward ACK in a
three-way handshake.
Fix it by only applying the reuseport check for full sockets.
Fixes: cf7fbe660f2d ("bpf: Add socket assign support")
Signed-off-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200408033540.10339-1-joe@wand.net.nz
Acked-by: Gary Lin <glin@suse.com>
---
net/core/filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5925,7 +5925,7 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff
return -EOPNOTSUPP;
if (unlikely(dev_net(skb->dev) != sock_net(sk)))
return -ENETUNREACH;
- if (unlikely(sk->sk_reuseport))
+ if (unlikely(sk_fullsock(sk) && sk->sk_reuseport))
return -ESOCKTNOSUPPORT;
if (sk_is_refcounted(sk) &&
unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))