Date: Fri,  4 Aug 2023 09:55:42 +0800
From: Geliang Tang <geliang.tang@...e.com>
To: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Florent Revest <revest@...omium.org>,
	Brendan Jackman <jackmanb@...omium.org>,
	Matthieu Baerts <matthieu.baerts@...sares.net>,
	Mat Martineau <martineau@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	John Johansen <john.johansen@...onical.com>,
	Paul Moore <paul@...l-moore.com>,
	James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Stephen Smalley <stephen.smalley.work@...il.com>,
	Eric Paris <eparis@...isplace.org>,
	Mykola Lysenko <mykolal@...com>,
	Shuah Khan <shuah@...nel.org>,
	Simon Horman <horms@...nel.org>
Cc: Geliang Tang <geliang.tang@...e.com>,
	bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	mptcp@...ts.linux.dev,
	apparmor@...ts.ubuntu.com,
	linux-security-module@...r.kernel.org,
	selinux@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: [PATCH bpf-next v10 0/5] bpf: Force to MPTCP

As is described in the "How to use MPTCP?" section in MPTCP wiki [1]:

"Your app should create sockets with IPPROTO_MPTCP as the proto:
( socket(AF_INET, SOCK_STREAM, IPPROTO_MPTCP); ). Legacy apps can be
forced to create and use MPTCP sockets instead of TCP ones via the
mptcpize command bundled with the mptcpd daemon."

But the mptcpize (LD_PRELOAD technique) command has some limitations
[2]:

 - it doesn't work if the application is not using libc (e.g. GoLang
apps)
 - in some envs, it might not be easy to set env vars / change the way
apps are launched, e.g. on Android
 - mptcpize needs to be launched with all apps that want MPTCP: we could
have more control from BPF to enable MPTCP only for some apps or all the
ones of a netns or a cgroup, etc.
 - it is not in BPF, we cannot talk about it at netdev conf.

So this patchset attempts to use BPF to implement functions similer to
mptcpize.

The main idea is to add a hook in sys_socket() to change the protocol id
from IPPROTO_TCP (or 0) to IPPROTO_MPTCP.

[1]
https://github.com/multipath-tcp/mptcp_net-next/wiki
[2]
https://github.com/multipath-tcp/mptcp_net-next/issues/79

v10:
 - drop "#ifdef CONFIG_BPF_JIT".
 - include vmlinux.h and bpf_tracing_net.h to avoid defining some
macros.
 - drop unneeded checks for mptcp.

v9:
 - update comment for 'update_socket_protocol'.

v8:
 - drop the additional checks on the 'protocol' value after the
'update_socket_protocol()' call.

v7:
 - add __weak and __diag_* for update_socket_protocol.

v6:
 - add update_socket_protocol.

v5:
 - add bpf_mptcpify helper.

v4:
 - use lsm_cgroup/socket_create

v3:
 - patch 8: char cmd[128]; -> char cmd[256];

v2:
 - Fix build selftests errors reported by CI

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/79

Geliang Tang (5):
  bpf: Add update_socket_protocol hook
  selftests/bpf: Use random netns name for mptcp
  selftests/bpf: Add two mptcp netns helpers
  selftests/bpf: Drop unneeded checks for mptcp
  selftests/bpf: Add mptcpify test

 net/mptcp/bpf.c                               |  15 ++
 net/socket.c                                  |  24 ++++
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 129 +++++++++++++++---
 tools/testing/selftests/bpf/progs/mptcpify.c  |  20 +++
 4 files changed, 169 insertions(+), 19 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/mptcpify.c

-- 
2.35.3

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