linux-kernel - Re: [RFC Patch v2] net: reserve ports for applications using fixedport numbers

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Message-ID: <4B6F81EF.4070103@redhat.com>
Date:	Mon, 08 Feb 2010 11:15:59 +0800
From:	Cong Wang <amwang@...hat.com>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
CC:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, opurdila@...acom.com,
	eric.dumazet@...il.com, linux-rdma@...r.kernel.org,
	netdev@...r.kernel.org, nhorman@...driver.com,
	linux-sctp@...r.kernel.org, davem@...emloft.net
Subject: Re: [RFC Patch v2] net: reserve ports for applications using fixedport
 numbers

Tetsuo Handa wrote:
> Cong Wang wrote:
>> Oh, IIUC, TOMOYO is something like SELinux?
> 
> Yes. It is a policy based mandatory access control implementation which is
> applied to not only non root users but also root user. If MAC is enabled,
> root user cannot freely modify via sysctl() or /proc/sys interface.
> 
>> So, it is somewhat weird to let users to use TOMOYO to reserve
>> the ports with MAC.
> 
> To add reserved port
> 
> echo deny_autobind 0-1023 | ccs-loadpolicy -e
> echo deny_autobind 3128 | ccs-loadpolicy -e
> echo deny_autobind 8080 | ccs-loadpolicy -e
> 
> and to delete reserved port
> 
> echo delete deny_autobind 0-1023 | ccs-loadpolicy -e
> echo delete deny_autobind 3128 | ccs-loadpolicy -e
> echo delete deny_autobind 8080 | ccs-loadpolicy -e
> 
> That's all. Quite easy.


Hmm, but you are solving a non-security problem with a security
tool, doesn't this look weird? ;-)

> 
>> For normal users /proc interface seems more friendly.
> 
> I think /proc/sys/net/ipv4/ip_local_reserved_ports interface wants
> "struct list_head" for handling multiple sets of min/max pairs. I'm using
> http://tomoyo.sourceforge.jp/cgi-bin/lxr/source/security/ccsecurity/autobind.c#L29
> for that purpose.


Yes, but I didn't plan to add multiple range support for
ip_local_reserved_ports, like ip_local_port_range.

Having that will be better but needs more efforts.

Thanks.
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