netdev - Re: [PATCH V3] netfilter: netns nf_conntrack: per-netns net.netfilter.nf_conntrack

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20250410131717.GA14051@breakpoint.cc>
Date: Thu, 10 Apr 2025 15:17:17 +0200
From: Florian Westphal <fw@...len.de>
To: lvxiafei <xiafei_xupt@....com>
Cc: fw@...len.de, coreteam@...filter.org, davem@...emloft.net,
	edumazet@...gle.com, horms@...nel.org, kadlec@...filter.org,
	kuba@...nel.org, linux-kernel@...r.kernel.org,
	lvxiafei@...setime.com, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org, pabeni@...hat.com,
	pablo@...filter.org
Subject: Re: [PATCH V3] netfilter: netns nf_conntrack: per-netns
 net.netfilter.nf_conntrack_max sysctl

lvxiafei <xiafei_xupt@....com> wrote:
> Florian Westphal <fw@...len.de> wrote:
> > I suggest to remove nf_conntrack_max as a global variable,
> > make net.nf_conntrack_max use init_net.nf_conntrack_max too internally,
> > so in the init_net both sysctls remain the same.
> 
> The nf_conntrack_max global variable is a system calculated
> value and should not be removed.
> nf_conntrack_max = max_factor * nf_conntrack_htable_size;

Thats the default calculation for the initial sysctl value:

net/netfilter/nf_conntrack_standalone.c:                .data           = &nf_conntrack_max,
net/netfilter/nf_conntrack_standalone.c:                .data           = &nf_conntrack_max,

You can make an initial patch that replaces all occurences of
nf_conntrack_max with cnet->sysctl_conntrack_max

(adding a 'unsigned int sysctl_conntrack_max' to struct
 nf_conntrack_net).

Then, in a second patch, remove the '0444' readonly and redirect
the child netns to use the copy in its own pernet area rather than the
init_net one.