From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4F8531917C6 for ; Thu, 29 Aug 2024 14:25:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724941523; cv=none; b=TE2B1r96ziP/xzhjAxP62xpo5m6For2C7oa4JgT0G9bmwkz1r50AaorGgq1pxc+nL3S8B3Eaq48zwTsb3ERFkbThffom0l8XqMKZw4dkp7J93u7P+d7vGfexg8gSThhluWbonMwv8OsveFNn+p+D6sOdlkpxlKQek0mRSVHlInw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724941523; c=relaxed/simple; bh=/hEtjd8gvdT7OgX03UbFKsTi0FiJb4eMN4TrELCAv5Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BQeF7Fu4PHo6ctOAEcwC3bej0vuq26pkWmXlai2eMGf5DB+8tKh4J/IXbAVK/rGiO/b6SWyI/Na47GyuQgIn2FnbhgBQJC0497RKUim4kHRxFjJJdm/GirPFBfm/2DT2M8mddttgJXCplQ5iqadYCJDxws2fmAnsp6eprbzkaKg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tDRBCyMb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tDRBCyMb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EAAC5C4CEC1; Thu, 29 Aug 2024 14:25:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724941522; bh=/hEtjd8gvdT7OgX03UbFKsTi0FiJb4eMN4TrELCAv5Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=tDRBCyMbJA2dZZw2Rh9rQfNl85FHKMg3TvwCCQVbR5UvzsE9u23/lKfEb3UB9rZOZ e83BmCL0X2McmKhQkLYJujiX6bhZIK4o6wx1Q52LwaBfNXEtKi9cciUWeHuNGxEKWI m2xngW2+g+EWyHhwZfEMJfr4bEZqAURRraRli5wVe6QShCbT+3hls5bS78ZeqPEbf4 fbWozyZMmcmDJGxp6n4GnGFSPlY3fwfuPZoafG7TwjG3tRLkFyQUGifvdl7UcymD6p 7j/XfE8QbtW3aLMTpIOnI4CDVhRHhbHk/qLnGx6YT1cHV+my2lnb2fJ1jTMhAVm+Vs CdE58P0hH2bpw== Message-ID: <7a04e174-a468-4e8d-9dae-013ca55066cb@kernel.org> Date: Thu, 29 Aug 2024 16:25:19 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-next v5 1/3] selftests/bpf: Add getsockopt to inspect mptcp subflow Content-Language: en-GB To: Geliang Tang , mptcp@lists.linux.dev Cc: Geliang Tang References: From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Geliang, cc: -Martin (not to annoy him with MPTCP specific stuff) On 29/08/2024 04:53, Geliang Tang wrote: > From: Geliang Tang > > This patch adds a "cgroup/getsockopt" way to inspect the subflows of a > mptcp socket. > > mptcp_for_each_stubflow() and other helpers related to list_dentry are > added into progs/mptcp_bpf.h. > > Add an extra "cgroup/getsockopt" prog to walk the msk->conn_list and use > bpf_core_cast to cast a pointer to tcp_sock for readonly. It will allow > to inspect all the fields in a tcp_sock. (...) > diff --git a/tools/testing/selftests/bpf/progs/mptcp_subflow.c b/tools/testing/selftests/bpf/progs/mptcp_subflow.c > index bc572e1d6df8..6a7cf71c2795 100644 > --- a/tools/testing/selftests/bpf/progs/mptcp_subflow.c > +++ b/tools/testing/selftests/bpf/progs/mptcp_subflow.c > @@ -4,6 +4,7 @@ > > /* vmlinux.h, bpf_helpers.h and other 'define' */ > #include "bpf_tracing_net.h" > +#include "mptcp_bpf.h" > > char _license[] SEC("license") = "GPL"; > > @@ -57,3 +58,64 @@ int mptcp_subflow(struct bpf_sock_ops *skops) > > return 1; > } > + > +static int _check_getsockopt_subflow_mark(struct mptcp_sock *msk, struct bpf_sockopt *ctx) > +{ > + struct mptcp_subflow_context *subflow; > + int i = 0; > + > + mptcp_for_each_subflow(msk, subflow) { > + struct sock *ssk; > + > + ssk = mptcp_subflow_tcp_sock(bpf_core_cast(subflow, > + struct mptcp_subflow_context)); > + > + if (ssk->sk_mark != ++i) > + ctx->retval = -1; > + } > + > + return 1; > +} > + > +static int _check_getsockopt_subflow_cc(struct mptcp_sock *msk, struct bpf_sockopt *ctx) > +{ > + struct mptcp_subflow_context *subflow, *tmp; > + > + mptcp_for_each_subflow_safe(msk, subflow, tmp) { Out of curiosity, why do you need the '_safe()' helper here? Just to check it works? > + struct inet_connection_sock *icsk; > + struct sock *ssk; > + > + ssk = mptcp_subflow_tcp_sock(bpf_core_cast(subflow, > + struct mptcp_subflow_context)); > + icsk = bpf_core_cast(ssk, struct inet_connection_sock); > + > + if ((ssk->sk_mark == 1 && > + __builtin_memcmp(icsk->icsk_ca_ops->name, cc, TCP_CA_NAME_MAX)) || In your previous version, you had a patch to set the cc on the other subflow, not to change the value of 'getsockopt(TCP_CONGESTION)' seen by the userspace. Why did you drop it? > + (ssk->sk_mark == 2 && > + __builtin_memcmp(icsk->icsk_ca_ops->name, "cubic", TCP_CA_NAME_MAX))) You cannot check this one (or at least not like that): the default TCP CC can be changed with a kernel config, it is not necessarily cubic. I think it is fine to only check the other subflow. > + ctx->retval = -1; Should you not mark it as an error if the mark is different from 1 or 2? (Or maybe not, because that's covered by _check_getsockopt_subflow_mark) > + } > + > + return 1; > +} > + > +SEC("cgroup/getsockopt") > +int _getsockopt_subflow(struct bpf_sockopt *ctx) > +{ > + struct bpf_sock *sk = ctx->sk; > + struct mptcp_sock *msk; > + > + if (!sk || sk->protocol != IPPROTO_MPTCP) > + return 1; If this test fails, the check will not be done. > + > + msk = bpf_core_cast(sk, struct mptcp_sock); > + if (msk->pm.subflows != 1) > + return 1; Same here: if there is no extra subflow, the test is silently not done. You change 'ctx->retval'. Also, it might be good to print something somewhere everywhere you set this 'ctx->retval' to -1, to be able to easily understand what went wrong, no? Can we use bpf_printk() or something similar? > + > + if (ctx->level == SOL_SOCKET && ctx->optname == SO_MARK) > + return _check_getsockopt_subflow_mark(msk, ctx); > + if (ctx->level == SOL_TCP && ctx->optname == TCP_CONGESTION) > + return _check_getsockopt_subflow_cc(msk, ctx); > + > + return 1; > +} Cheers, Matt -- Sponsored by the NGI0 Core fund.