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 6010E18C21 for ; Fri, 18 Aug 2023 15:26:24 +0000 (UTC) Received: from out-5.mta1.migadu.com (out-5.mta1.migadu.com [IPv6:2001:41d0:203:375::5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3189D3C3D for ; Fri, 18 Aug 2023 08:26:22 -0700 (PDT) Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1692372380; 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=rpOkpEVZn5CL5W7EAycreIplkq31utU1vc2qT8RLF0I=; b=eBSx5X1E+DVJxnvdttP+6LGiobNZ2bXieBHa4SYqjjpROll57ltjQHcGaqQuIsY2HRil/w H4f++ByqLdjgVDSFB1I2rb2uicMilticELsV3OLADKQ70uGWAuPiZHzEWRH4CGdc4JfiOB 7MMqkNOEj6wpi9+abF+K/C+jZFB5YIg= Date: Fri, 18 Aug 2023 08:26:06 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reply-To: yonghong.song@linux.dev Subject: Re: [PATCH bpf-next v14 1/4] bpf: Add update_socket_protocol hook Content-Language: en-US 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, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20230818082417.GA20274@bogon> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20230818082417.GA20274@bogon> 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,URIBL_BLOCKED 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 8/18/23 1:24 AM, Geliang Tang wrote: > On Wed, Aug 16, 2023 at 09:11:56AM +0800, 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 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 >> Acked-by: Yonghong Song >> Signed-off-by: Geliang Tang >> --- >> net/mptcp/bpf.c | 15 +++++++++++++++ >> net/socket.c | 26 +++++++++++++++++++++++++- >> 2 files changed, 40 insertions(+), 1 deletion(-) >> >> diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c >> index 5a0a84ad94af..8a16672b94e2 100644 >> --- a/net/mptcp/bpf.c >> +++ b/net/mptcp/bpf.c >> @@ -19,3 +19,18 @@ struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk) >> >> return NULL; >> } >> + >> +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); >> diff --git a/net/socket.c b/net/socket.c >> index 5d4e37595e9a..fdb5233bf560 100644 >> --- a/net/socket.c >> +++ b/net/socket.c >> @@ -1657,12 +1657,36 @@ 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", >> + "A fmod_ret entry point for BPF programs"); > > Hi Martin & Yonghong, > > I got a sparse warning for this new added 'update_socket_protocol': > > > touch net/socket.c && make C=1 net/socket.o > > net/socket.c:1676:21: warning: symbol 'update_socket_protocol' was not declared. Should it be static? This is a sparse warning. Let us ignore it for now. We already have __diag_ignore for missing prototypes in the above, but sparse won't recognize them. Also, 'static' is conflict with '__weak' attribute, and we cannot remove '__weak' attribute. > > What should I do to fix it, or should I just leave it here? Please give > me some suggestions. > > Thanks, > -Geliang > >> + >> +__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; >> >> - sock = __sys_socket_create(family, type, protocol); >> + sock = __sys_socket_create(family, type, >> + update_socket_protocol(family, type, protocol)); >> if (IS_ERR(sock)) >> return PTR_ERR(sock); >> >> -- >> 2.35.3 >> >