From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 111FBEA0 for ; Thu, 3 Aug 2023 23:27:20 +0000 (UTC) X-Greylist: delayed 559 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Thu, 03 Aug 2023 16:27:17 PDT Received: from out-96.mta1.migadu.com (out-96.mta1.migadu.com [95.215.58.96]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AB5F1BFD for ; Thu, 3 Aug 2023 16:27:16 -0700 (PDT) Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1691104672; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5UcTW2ZerF3E/NIit4kPDouCVNTX9RBlsI5Ewa1ULsM=; b=Fsjc8Ltt0taLpi+MclSzQBt+8MTlUJ8c8vCqPf13fjSwgX7el+/jK+lMzp6L2Lw0CINOpz 50OxThDABRzHVgXUkfNL3OZ+ItQ7RrAD0W0Vdm14Q38UTuGef0HnHmGb2an9ilV3nzU2gi RosNEGLXB9iKVo09A0d+mcpJ3il/vFg= Date: Thu, 3 Aug 2023 16:17:37 -0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reply-To: yonghong.song@linux.dev Subject: Re: [PATCH bpf-next v9 1/4] bpf: Add update_socket_protocol hook To: Geliang Tang , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Florent Revest , Brendan Jackman , Matthieu Baerts , Mat Martineau , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris , Mykola Lysenko , Shuah Khan , Simon Horman Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, mptcp@lists.linux.dev, apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org References: Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 8/3/23 6:41 AM, Geliang Tang wrote: > 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 mod_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 > Signed-off-by: Geliang Tang > --- > net/mptcp/bpf.c | 17 +++++++++++++++++ > net/socket.c | 24 ++++++++++++++++++++++++ > 2 files changed, 41 insertions(+) > > diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c > index 5a0a84ad94af..c43aee31014d 100644 > --- a/net/mptcp/bpf.c > +++ b/net/mptcp/bpf.c > @@ -12,6 +12,23 @@ > #include > #include "protocol.h" > > +#ifdef CONFIG_BPF_JIT Is this necessary? Most other register_btf_* functions do not have a config like this. > +BTF_SET8_START(bpf_mptcp_fmodret_ids) > +BTF_ID_FLAGS(func, update_socket_protocol) > +BTF_SET8_END(bpf_mptcp_fmodret_ids) > + > +static const struct btf_kfunc_id_set bpf_mptcp_fmodret_set = { > + .owner = THIS_MODULE, > + .set = &bpf_mptcp_fmodret_ids, > +}; > + > +static int __init bpf_mptcp_kfunc_init(void) > +{ > + return register_btf_fmodret_id_set(&bpf_mptcp_fmodret_set); > +} > +late_initcall(bpf_mptcp_kfunc_init); > +#endif /* CONFIG_BPF_JIT */ > + > struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk) > { > if (sk && sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk)) > diff --git a/net/socket.c b/net/socket.c > index 2b0e54b2405c..9f98ced88ac5 100644 > --- a/net/socket.c > +++ b/net/socket.c > @@ -1644,11 +1644,35 @@ struct file *__sys_socket_file(int family, int type, int protocol) > return sock_alloc_file(sock, flags, NULL); > } > > +/* A hook for bpf progs to attach to and update socket protocol. > + * > + * A static noinline declaration here could cause the compiler to > + * optimize away the function. A global noinline declaration will > + * keep the definition, but may optimize away the callsite. > + * Therefore, __weak is needed to ensure that the call is still > + * emitted, by telling the compiler that we don't know what the > + * function might eventually be. > + * > + * __diag_* below are needed to dismiss the missing prototype warning. > + */ > + > +__diag_push(); > +__diag_ignore_all("-Wmissing-prototypes", > + "kfuncs which will be used in BPF programs"); > + > +__weak noinline int update_socket_protocol(int family, int type, int protocol) > +{ > + return protocol; > +} > + > +__diag_pop(); > + > int __sys_socket(int family, int type, int protocol) > { > struct socket *sock; > int flags; > > + protocol = update_socket_protocol(family, type, protocol); > sock = __sys_socket_create(family, type, protocol); > if (IS_ERR(sock)) > return PTR_ERR(sock);