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From: Kuniyuki Iwashima To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi Cc: Amery Hung , Yonghong Song , John Fastabend , Stanislav Fomichev , Eric Dumazet , Neal Cardwell , Willem de Bruijn , Tenzin Ukyab , "=?UTF-8?q?Cl=C3=A9ment=20L=C3=A9ger?=" , Kuniyuki Iwashima , Kuniyuki Iwashima , bpf@vger.kernel.org, netdev@vger.kernel.org Content-Type: text/plain; charset="UTF-8" The next patch exposes a new kfunc calling __tcp_set_rcvlowat() to bpf_tcp_ops. MPTCP has its own sock->ops->set_rcvlowat() / mptcp_set_rcvlowat(), so we should not allow calling __tcp_set_rcvlowat() on MPTCP subflows. Let's disable BPF_TCP_OPS_FLAG_RCVQ for MPTCP for now. If needed in the future, bpf_tcp_ops_set_rcvlowat() could be extended to properly support MPTCP. Signed-off-by: Kuniyuki Iwashima --- net/ipv4/bpf_tcp_ops.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/bpf_tcp_ops.c b/net/ipv4/bpf_tcp_ops.c index dafe2337f9fc..c73d3478a8d5 100644 --- a/net/ipv4/bpf_tcp_ops.c +++ b/net/ipv4/bpf_tcp_ops.c @@ -347,6 +347,9 @@ __bpf_kfunc int bpf_tcp_ops_set_flags(struct tcp_sock *tp, u32 enable, u32 disab if ((enable & disable) || (enable | disable) & ~BPF_TCP_OPS_FLAG_ALL) return -EINVAL; + if (sk_is_mptcp((struct sock *)tp) && (enable & BPF_TCP_OPS_FLAG_RCVQ)) + return -EOPNOTSUPP; + old = READ_ONCE(tp->bpf_tcp_ops_flags); do { -- 2.56.0.rc1.315.gc6ed9934b7-goog