[PATCH v3 00/11] Add namespace support for syslog

From: Rui Xiang
Date: Wed Aug 07 2013 - 03:37:37 EST

This patchset introduces a system log namespace.

In container scenario, all logs are exported to the ring
buffer of host. Then logs belong to a contaier can't be
distinguished. Sometimes, Some of our guest are
administered by other sys-admin, that should not have
access to these infomations.

Syslog namespace is used to include a independent log
buf own to a container, some logs which need to be
displayed in container are stored to the buf, and others
are all exported to HOST.

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. The 2nd version
(http://lwn.net/Articles/561271/) used these important
advice, and referred to Serge's patch

In this patchset, patch01-10 implement a mechanism for
syslog_ns. Iptables is an actual scene to use syslog ns.
So patch11 uses ns_printk interface to isolate logs.

Syslog namespace is tied to a user namespace. And 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

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.

v1 --> v2:
-- Add syslog_ns to user namespace instead of nsproxy.
-- Create syslog_ns through a new command(11) to __NR_syslog
syscall instead of CLONE_SYSLOG.
-- Alter related interfaces and parameters.

v2 --> v3:
-- Add some changlogs to illustrate the purpose of syslog ns.
-- Add ns_printk_emit for namespace and make devkmsg_writev
per namespace.
-- Add ns_console_unlock for namespace.
-- Put user ns while freeing syslog_ns.
-- Use net instead of skb->dev->nd_net in sb_close.
-- Clean up.

Rui Xiang (11):
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
syslog_ns: implement ns_printk_emit for specific syslog_ns
syslog_ns: implement ns_console_unlock for specific syslog_ns
netfilter: use ns_printk in iptable context

fs/proc/kmsg.c | 17 +-
include/linux/console.h | 1 +
include/linux/printk.h | 11 +-
include/linux/syslog.h | 81 ++++-
include/linux/user_namespace.h | 2 +
include/net/netfilter/xt_log.h | 6 +-
kernel/printk.c | 784 +++++++++++++++++++++++++++--------------
kernel/sysctl.c | 3 +-
kernel/user.c | 3 +
kernel/user_namespace.c | 4 +
net/netfilter/xt_LOG.c | 4 +-
11 files changed, 636 insertions(+), 280 deletions(-)


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