[转]How to disable SELinux

 参考两个文章：

http://www.haw-haw.org/node/30：这个文章主要是说怎样disable掉SELinux
http://www.crypt.gen.nz/selinux/disable_selinux.html：这个文章比较细的说明了相关问题。
我把两个都copy到这里来

文章一：

selinux是个新东东

在linux kernel 2.6的系统（如as4、fc3）里常见

一般如果在2.6的kernel的机器上出什么莫名其妙的权限的错误

大家都可以想想是不是selinux的策略问题

以我现在的想法

最好是已开始就把selinux disable掉！

方法是编辑文件/etc/sysconfig/selinux

把SELINUX设为disabled

像这样：

SELINUX=disabled

在重起机器selinux就被忽略了

命令setenforce 0可以直接干掉selinux 直接生效

不用重启机器

文章二：

You've setup a new system, or installed something new on your Linux
system and its not working. You get the feeling that SELinux is the
cause of the problem. This page was written to help.

Contents

      Overview

      Should you really disable SELinux?

      Temporarily switch off enforcement

      Permanently Permissive

      Fully Disabling SELinux

      Re-Enabling SELinux

Overview

SELinux has two major components on your system. There's the kernel
mechanism which is enforcing a bunch of access rules which apply to
processes and files. And secondly, there's file labels : every
file on your system has extra labels attached to it which tie-in with
those access rules. Run ls -Z and you'll see what I mean.

Should you really disable SELinux?

Be aware that by disabling SELinux you will be removing a security
mechanism on your system. Think about this carefully, and if your
system is on the Internet and accessed by the public, then think about
it some more. Joshua Brindle (an SELinux developer) has comments on
disabling SELinux here,
which states clearly that applications should be fixed to work with
SELinux, rather than disabling the OS security mechanism.

You need to decide if you want to disable SELinux temporarily to
test the problem, or permanently switch it off. It may also be a
better option to make changes to the policy to permit the operations
that are being blocked - but this requires knowledge of writing
policies and may be a steep learning curve for some people.

For the operating system as a whole, there is two kinds of disabling:

Permissive - switch the SELinux kernel into a mode where
every operation is allowed. Operations that would be denied are
allowed and a message is logged identifying that it would be
denied. The mechanism that defines labels for files which are being
created/changed is still active.

Disabled - SELinux is completely switched off in the kernel. This
allows all operations to be permitted, and also disables the process
which decides what to label files & processes with.

Disabling SELinux could lead to problems if you want to re-enable it
again later. When the system runs with file labelling disable it will
create files with no label - which could cause problems if the system
is booted into Enforcement mode. A full re-labelling of the file
system will be necessary.

Temporarily switch off enforcement

You can switch the system into permissive mode with the following command:

You'll need to be logged in as root, and in the sysadm_r role:

To switch back into enforcing mode:

In Fedora Core and RedHat Enterprise Linux you can use the setenforce command with a 0 or 1 option to
set permissive or enforcing mode, its just a slightly easier command
than the above.

To check what mode the system is in,



which will print a "0" or "1" for permissive or enforcing - probably
printed at the beginning of the line of the command prompt.

Permanently Permissive

The above will switch off enforcement temporarily - until you reboot
the system. If you want the system to always start in permissive mode,
then here is how you do it.

In Fedora Core and RedHat Enterprise, edit /etc/selinux/config and you will see some lines like this:



... just change SELINUX=enforcing to SELINUX=permissive, and you're done. Reboot if you want to prove it.

For the other Linuxes which don't have the /etc/selinux/config file, you just need to edit the kernel boot line, usually in /boot/grub/grub.conf if you're using the GRUB boot loader. On the kernel line, add enforcing=0 at the end. For example,

Fully Disabling SELinux

Fully disabling SELinux goes one step further than just switching into
permissive mode. Disabling will completely disable all SELinux
functions including file and process labelling.

In Fedora Core and RedHat Enterprise, edit /etc/selinux/config and change the SELINUX line to SELINUX=disabled:



... and then reboot the system.

For the other Linuxes which don't have the /etc/selinux/config file, you just need to
edit the kernel boot line, usually in /boot/grub/grub.conf, if you're using the
GRUB boot loader. On the kernel line, add selinux=0 at the end. For example,



You will have to reboot to disable SELinux, you just can't do it while the system is running.

Re-Enabling SELinux

If you've disabled SELinux as in the section above, and you want to
enable it again then you've got a bit of work to do. The problem will
be that files created or changed when SELinux was disabled won't have
the correct file labels on them - if you just reboot in enforcing mode then
a lot of stuff won't work properly.

What you need to do is to enable SELinux by editing /etc/selinux/config (for Fedora/RedHat) or by adding selinux=1 to the kernel boot line, then boot into permissive mode, then
relabel everything, and then reboot into (or simply switch to)
enforcing mode.

After booting into permissive mode, run

fixfiles relabel

Alternatively, in Fedora and RedHat Enterprise Linux you can run

touch /.autorelabel

and reboot or put

autorelabel

on the boot command line - in both cases the file system gets a full
relabel early in the boot process. Note that this can take quite some
time for systems with a large number of files.

After relabelling the filesystem, you can switch to enforcing
mode (see above) and your system should be fully enforcing again.