[MPTCP] force existing service to use MPTCP

[MPTCP] force existing service to use MPTCP

[Paolo Abeni]

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hello,

reviving this old topic.

I've experimented a bit with the LD_PRELOAD thing.

Looks like at least nginx and apache can be forced to use MPTCP instead
of TCP with a crafted unit file created automatically from the distro-
provided one.

e.g. for nginx, adding:

Conflicts=nginx.service
After=nginx.service

into the [unit] section, and:

Environment="LD_PRELOAD=/usr/lib64/use_mptcp.so"
ExecStartPre=sysctl -w net.mptcp.enabled=1

into the [Service] section.

Then I had to fight a bit with selinux. I did not really investigate
the issue, I think/fear selinux misunderstood mptcp sockets as raw
ones, so default policy fails. A bunch of:

ausearch -c 'nginx' --raw | audit2allow -M my-nginx
semodule -i my-nginx.pp

solved the problem.

Bottom line:
- the above looks tecnically viable [at least for some services]. I'm
looking for a more extended service/daemon list to investigate
fourther. I think we could/should really consider package the above in
mptcpd or the like.
- selinux (surprise, surprise!) can be a problem. Worth looking at it
(that is independent from the system we will pick to force MPTCP socket
usage)

Cheers,

Paolo