linux-kernel - Re: [PATCH v3 04/11] syslog_ns: make syslog handling per namespace

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Message-ID: <1375901563.2644.84.camel@deadeye.wl.decadent.org.uk>
Date:	Wed, 7 Aug 2013 20:52:43 +0200
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Rui Xiang <rui.xiang@...wei.com>
CC:	<containers@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
	<netfilter-devel@...r.kernel.org>, <serge.hallyn@...ntu.com>,
	<ebiederm@...ssion.com>, <akpm@...ux-foundation.org>,
	<gaofeng@...fujitsu.com>, <guz.fnst@...fujitsu.com>,
	<libo.chen@...wei.com>
Subject: Re: [PATCH v3 04/11] syslog_ns: make syslog handling per namespace

On Wed, 2013-08-07 at 15:37 +0800, Rui Xiang wrote:
> This patch makes syslog buf and other fields per
> namespace.
> 
> Here use ns->log_buf(log_buf_len, logbuf_lock,
> log_first_seq, logbuf_lock, and so on) fields
> instead of global ones to handle syslog.
[...]
> --- a/kernel/printk.c
> +++ b/kernel/printk.c
[...]
>  }
>  
> -#ifdef CONFIG_SECURITY_DMESG_RESTRICT
> -int dmesg_restrict = 1;
> -#else
> -int dmesg_restrict;
> -#endif
> -
> -static int syslog_action_restricted(int type)
> +static int syslog_action_restricted(int type,
> +			struct syslog_namespace *ns)
>  {
> -	if (dmesg_restrict)
> +	if (ns->dmesg_restrict)
>  		return 1;
>  	/*
>  	 * Unless restricted, we allow "read all" and "get buffer size"
[...]

I don't think this should be a per-namespace setting.  And it certainly
should not be possible for child namespaces to disable dmesg_restrict if
it is enabled by a parent namespace.

In later patches, it appears to be copied into child namespaces but not
made visible or controllable there.  So if an administrator enables
dmesg_restrict in the initial syslog namespace after another syslog
namespace has been created, she won't be able to tell that it is still
disabled in that other namespace.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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