netdev - Re: Why max netlink msg size is limited to 16k

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1492875381.6453.34.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Sat, 22 Apr 2017 08:36:21 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     prashantkumar dhotre <prashantkumardhotre@...il.com>
Cc:     netdev@...r.kernel.org
Subject: Re: Why max netlink msg size is limited to 16k

On Sat, 2017-04-22 at 19:43 +0530, prashantkumar dhotre wrote:
> I am observing that max netlink msg that my kernel module can send to
> user app is close to 16K.
> 
> For larger sizes, genlmsg_unicast() succeeds but my app does not receive data.
> 
> I have tried increasing RECV buffer size in my user app but that does not help.
> 
> Regards


You need a kernel >= linux-4.9 to get about 32KB 

Why is this limited ? Please read 

https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=d35c99ff77ecb2eb239731b799386f3b3637a31e