Commit 8e368dc7 authored Apr 07, 2020 by Joe Stringer Committed by Daniel Borkmann Apr 09, 2020

bpf: Fix use of sk->sk_reuseport from sk_assign



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: cf7fbe66 ("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

parent eb203f4b

net/core/filter.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5925,7 +5925,7 @@ BPF_CALL_3(bpf_sk_assign, struct sk_buff , skb, struct sock , sk, u64, flags)
		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)))

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