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	Add a hook named update_socket_protocol in __sys_socket(), for bpf progs to attach to and update socket protocol. One user case is to force legacy TCP apps to create and use MPTCP sockets instead of TCP ones. Define a fmod_ret set named bpf_mptcp_fmodret_ids, add the hook update_socket_protocol into this set, and register it in bpf_mptcp_kfunc_init(). Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/79 Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net> Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Geliang Tang <geliang.tang@suse.com> Link: https://lore.kernel.org/r/ac84be00f97072a46f8a72b4e2be46cbb7fa5053.1692147782.git.geliang.tang@suse.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
		
			
				
	
	
		
			36 lines
		
	
	
	
		
			872 B
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			36 lines
		
	
	
	
		
			872 B
		
	
	
	
		
			C
		
	
	
	
	
	
// SPDX-License-Identifier: GPL-2.0
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/* Multipath TCP
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 *
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 * Copyright (c) 2020, Tessares SA.
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 * Copyright (c) 2022, SUSE.
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 *
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 * Author: Nicolas Rybowski <nicolas.rybowski@tessares.net>
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 */
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#define pr_fmt(fmt) "MPTCP: " fmt
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#include <linux/bpf.h>
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#include "protocol.h"
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struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk)
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{
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	if (sk && sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
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		return mptcp_sk(mptcp_subflow_ctx(sk)->conn);
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	return NULL;
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}
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BTF_SET8_START(bpf_mptcp_fmodret_ids)
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BTF_ID_FLAGS(func, update_socket_protocol)
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BTF_SET8_END(bpf_mptcp_fmodret_ids)
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static const struct btf_kfunc_id_set bpf_mptcp_fmodret_set = {
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	.owner = THIS_MODULE,
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	.set   = &bpf_mptcp_fmodret_ids,
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};
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static int __init bpf_mptcp_kfunc_init(void)
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{
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	return register_btf_fmodret_id_set(&bpf_mptcp_fmodret_set);
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}
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late_initcall(bpf_mptcp_kfunc_init);
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