netdev - Re: [PATCH net-next] net/ipv4/sysctl: show tcp_{allowed,available}_congestion

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Date:   Wed, 19 Feb 2020 11:04:44 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     christian.brauner@...ntu.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org, kuba@...nel.org,
        haw.loeung@...onical.com
Subject: Re: [PATCH net-next] net/ipv4/sysctl: show
 tcp_{allowed,available}_congestion_control in non-initial netns

From: Christian Brauner <christian.brauner@...ntu.com>
Date: Wed, 19 Feb 2020 13:02:53 +0100

> It is currenty possible to switch the TCP congestion control algorithm
> in non-initial network namespaces:
> 
> unshare -U --map-root --net --fork --pid --mount-proc
> echo "reno" > /proc/sys/net/ipv4/tcp_congestion_control
> 
> works just fine. But currently non-initial network namespaces have no
> way of kowing which congestion algorithms are available or allowed other
> than through trial and error by writing the names of the algorithms into
> the aforementioned file.
> Since we already allow changing the congestion algorithm in non-initial
> network namespaces by exposing the tcp_congestion_control file there is
> no reason to not also expose the
> tcp_{allowed,available}_congestion_control files to non-initial network
> namespaces. After this change a container with a separate network
> namespace will show:
> 
> root@f1:~# ls -al /proc/sys/net/ipv4/tcp_* | grep congestion
> -rw-r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_allowed_congestion_control
> -r--r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_available_congestion_control
> -rw-r--r-- 1 root root 0 Feb 19 11:54 /proc/sys/net/ipv4/tcp_congestion_control
> 
> Link: https://github.com/lxc/lxc/issues/3267
> Reported-by: Haw Loeung <haw.loeung@...onical.com>
> Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>

Applied, thank you.