linux-kernel - Re: [PATCH 0/9] Add namespace support for syslog v2

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Date:	Tue, 30 Jul 2013 10:11:48 +0800
From:	Rui Xiang <rui.xiang@...wei.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	<containers@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>, <serge.hallyn@...ntu.com>,
	<akpm@...ux-foundation.org>, <gaofeng@...fujitsu.com>,
	<libo.chen@...wei.com>
Subject: Re: [PATCH 0/9] Add namespace support for syslog v2


Hi Eric,

Thanks for your attention.


On 2013/7/30 2:58, Eric W. Biederman wrote:
> Rui Xiang <rui.xiang@...wei.com> writes:
> 
>> This patchset introduces a system log namespace.
> 
> The largest outstanding question is not answered.  Can't we just fix
> iptables to log somehwere better than dmesg, and would that not entirely
> remove the need for this work?
> 
I don't think there is any question. In this patchset, patch(1-8) implement
a mechanism for syslog_ns. And iptables is an actual scene to use ns. So we
can treat patch9 as a instance for syslog_ns.

Sorry for my negligence, I will add some detailed logs in next version.


Thanks.

> That question needs to be answered before we proceed down this path.
> 
> Eric
> 
>> It is the 2nd version. The link of the 1st version is 
>> http://lwn.net/Articles/525728/. In that version, syslog_
>> namespace was added into nsproxy and created through a new
>> clone flag CLONE_SYSLOG when cloning a process. 
>>
>> There were some discussion in last November about the 1st 
>> version. This version used these important advice, and 
>> referred to Serge's patch(http://lwn.net/Articles/525629/).
>>
>> Unlike the 1st version, in this patchset, syslog namespace 
>> is tied to a user namespace. Add we must create a new user 
>> ns before create a new syslog ns, because that will make 
>> users have full capabilities in this new userns after 
>> cloning a new user ns. The syslog namespace can be created 
>> through a new command(11) to __NR_syslog syscall. That owe 
>> to a new syslog flag SYSLOG_ACTION_NEW_NS.
>>
>> In syslog_namespace, some necessary identifiers for handling 
>> syslog buf are containerized. When one container creates a
>> new syslog ns, individual buf will be allocated to store log
>> ownned this container. 
>>
>> A new interface ns_printk is added to print the logs which 
>> we want to see in the container. Through ns_printk, we can 
>> get more logs related to a specific net ns, for instance, 
>> iptables. Here we use it to report iptable logs per 
>> contianer.
>>
>> Then default printk targeted at the init_syslog_ns will 
>> continue to print out most kernel log to host.
>>
>> One task in a new syslog ns could affect only current 
>> container through "dmesg", "dmesg -c" and /dev/kmsg 
>> actions. The read/write interface such as /dev/kmsg, 
>> /pro/kmsg and syslog syscall continue to be useful for 
>> container users.
>>
>> This patchset is based on linus' linux tree.
>>
>> Rui Xiang (9):
>>   syslog_ns: add syslog_namespace and put/get_syslog_ns
>>   syslog_ns: add syslog_ns into user_namespace
>>   syslog_ns: add init syslog_ns for global syslog
>>   syslog_ns: make syslog handling per namespace
>>   syslog_ns: make permisiion check per user namespace
>>   syslog_ns: use init syslog_ns for console action
>>   syslog_ns: implement function for creating syslog ns
>>   syslog_ns: implement ns_printk for specific syslog_ns
>>   netfilter: use ns_printk in iptable context
>>
>>  fs/proc/kmsg.c                 |  17 +-
>>  include/linux/printk.h         |   5 +-
>>  include/linux/syslog.h         |  79 ++++-
>>  include/linux/user_namespace.h |   2 +
>>  include/net/netfilter/xt_log.h |   6 +-
>>  kernel/printk.c                | 642 ++++++++++++++++++++++++-----------------
>>  kernel/sysctl.c                |   3 +-
>>  kernel/user.c                  |   3 +
>>  kernel/user_namespace.c        |   4 +
>>  net/netfilter/xt_LOG.c         |   4 +-
>>  10 files changed, 493 insertions(+), 272 deletions(-)
> 
> .
> 


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