linux-kernel - Re: [PATCH v2 1/1] sctp: sysctl: make extra pointers netns aware

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Message-ID: <Y4CzjgncdsrEe8tg@t14s.localdomain>
Date:   Fri, 25 Nov 2022 09:22:38 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Firo Yang <firo.yang@...e.com>
Cc:     vyasevich@...il.com, nhorman@...driver.com, mkubecek@...e.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, linux-sctp@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        firogm@...il.com
Subject: Re: [PATCH v2 1/1] sctp: sysctl: make extra pointers netns aware

On Fri, Nov 25, 2022 at 08:11:27PM +0800, Firo Yang wrote:
> Recently, a customer reported that from their container whose
> net namespace is different to the host's init_net, they can't set
> the container's net.sctp.rto_max to any value smaller than
> init_net.sctp.rto_min.
> 
> For instance,
> Host:
> sudo sysctl net.sctp.rto_min
> net.sctp.rto_min = 1000
> 
> Container:
> echo 100 > /mnt/proc-net/sctp/rto_min
> echo 400 > /mnt/proc-net/sctp/rto_max
> echo: write error: Invalid argument
> 
> This is caused by the check made from this'commit 4f3fdf3bc59c
> ("sctp: add check rto_min and rto_max in sysctl")'
> When validating the input value, it's always referring the boundary
> value set for the init_net namespace.
> 
> Having container's rto_max smaller than host's init_net.sctp.rto_min
> does make sense. Consider that the rto between two containers on the
> same host is very likely smaller than it for two hosts.
> 
> So to fix this problem, as suggested by Marcelo, this patch makes the
> extra pointers of rto_min, rto_max, pf_retrans, and ps_retrans point
> to the corresponding variables from the newly created net namespace while
> the new net namespace is being registered in sctp_sysctl_net_register.
> 
> Fixes: 4f3fdf3bc59c ("sctp: add check rto_min and rto_max in sysctl")
> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
> Signed-off-by: Firo Yang <firo.yang@...e.com>

and
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>

Thanks Firo.