SELinux

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This page is a translated version of the page SELinux and the translation is 20% complete.
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Bu sayfada, web sunucunuzun (muhtemelen Apache) bunlara erişebilmesi için SELinux [1] bağlamlarının ve boolelerin doğru şekilde nasıl ayarlanacağı açıklanmaktadır.

Alternatif olarak, aşağıdaki komutlardan birini kullanarak SELinux'u yalnızca httpd için devre dışı bırakabilirsiniz, böylece bu sorunlar geliştirme sırasında bir faktör değildir:

  • setsebool -P httpd_disable_trans false
  • semodule -r httpd
  • semanage permissive -a httpd_t

Sistem yapılandırmanıza bağlı olarak bu komut satırlarından hangisinin uygun olduğunu belirlemeniz gerekir.

Her durumda, komutu root kullanıcısı olarak çalıştırmalısınız.

SELinux çalıştıran bir sistemde kurulum MediaWiki için aşağıdaki ek adımlar gerçekleştirilmelidir:

chcon -R -t httpd_user_content_t /path/to/mediawiki_install

PHP dosya bilgisi uzantısını oluşturduktan sonra:

chcon -t httpd_sys_script_exec_t  /usr/lib/php/modules/fileinfo.so

Apache tarafından çalıştırılacak ek dosyalar httpd_user_script_exec_t (PHP dosyaları hariç) olmalıdır. httpd_*_script_exec_t olan dosyalar apache işlemi tarafından yazılamaz. İdeal olarak, MediaWiki yürütülebilir (PHP) dosyalarının tümü httpd_user_script_exec_t olarak ayarlanmalıdır, ancak geçerli SELinux ilkesi için bu gerekli değildir.

Yükleme dizinleri

Yapılandırmanızda yüklemeler etkinleştirilirse, dosya yükleme işlemi sırasında kullanılan tmp dizini nedeniyle bir bağlam sorunuyla karşılaşabilirsiniz. Creating a tmp directory in /var/www/ instead of using /tmp or the 'default setting' for upload_tmp_dir in /etc/php.ini can get around this problem. Be sure to correctly chmod chgrp and chcon this new tmp directory.

Uploading images

If the MediaWiki directories were copied or moved to migrate from an old system to another system that has SELinux enabled (enforcing) then the copied/moved files and directories may not have the correct SELinux context types. If this is the case, image uploads and thumbnail creation could be prevented by SELinux enforcement even if the owner and permissions are already set correctly. The includes/GlobalFunctions.php script file (and possibly other .php files in the MediaWiki install directory) must have the SELinux context type httpd_sys_script_exec_t to permits use of the PHP function.mkdir command. Without the correct context on the script, file uploads or thumbnail creation may fail on the attempt to create a hashed directory on the server. From the wiki base install directory, check for the correct SELinux context by entering the command:

ls -Z includes/GlobalFunctions.php

If the listed SELinux security context type is not httpd_sys_script_exec_t, change it with the command:

chcon -t httpd_sys_script_exec_t includes/GlobalFunctions.php

Assuming the permissions (755) and owner (usually 'apache') on the images directory are correct, the entire images directory tree must have the httpd_sys_script_rw_t SELinux context type so that scripts (.php files) running in the web server process are allowed read/write access. Check this with the command:

ls -dZ images

If the listed SELinux security context type is not httpd_user_rw_content_t, change it with the command:

chcon -R -t httpd_user_rw_content_t images

Thumbnail generation may fail with error messages like ulimit: cpu time/virtual memory/file size: cannot modify limit: Permission denied. To allow this you should enable httpd_setrlimit:

setsebool -P httpd_setrlimit 1

Debug logging file

If you want to store your MediaWiki wfDebug() logs into a file, and have followed the How to debug page thoroughly but nothing gets written to your logging file, you might need to set the SELinux context of the logging file to httpd_sys_script_rw_t using the following command:

chcon -t httpd_sys_script_rw_t /path/to/your/debug/file

Enabling InstantCommons

If you want to enable the InstantCommons feature on your wiki, and your OS implements SElinux, you should first tell Selinux to allow HTTPD scripts and modules to connect to the network. To do so, enter the following command:

getsebool -a

See what is the value of the boolean: httpd_can_network_connect. If it is set to on already, nothing needs to be done, Selinux will not prevent HTTPD scripts and modules from connecting to the network. However, if it is set to off, enter the following command line to activate it permanently:

setsebool -P httpd_can_network_connect on

The -P option means permanently. If you do not use it, the value of the boolean will be reinitialized on your next system reboot.

That is it. Make sure the modification was implemented successfully by issuing getsebool -a one more time, and verifying the value was updated correctly. If that is the case, you can now enable InstantCommons successfully.

Sending emails

E-posta s from MediaWiki may not work at all, or you may get Unknown error on actions that trigger an email. You need to enable sending emails from the webserver. The following command may enable this:

setsebool -P httpd_can_sendmail on

Pygments for SyntaxHighlight

This section is under discussion on the Talk page.

Extension:SyntaxHighlight use a library called pygments that provides the syntax highlight. If Syntax highlight doesn't work you may need to enable execution on the pygments folder:

semanage fcontext -a -t httpd_sys_script_exec_t '/<path_to_mediawiki>/extensions/SyntaxHighlight_GeSHi/pygments(/.*)?'
restorecon -R -v /<path_to_mediawiki>/extensions/SyntaxHighlight_GeSHi/pygments/

Other handy SELinux tricks

To find out if SELinux is enabled on your system:

getenforce

audit2allow is a perl script that interprets the selinux errors and constructs the right rules to overcome various problems.

/usr/bin/audit2allow -i /var/log/messages

It outputs the lines you need to add to your policies to permit things that are reported as failing.

In /var/log/messages you should find an id corresponding to the selinux error that occurred.

sealert -l <id>

will give more information. One possible source of error is that you copied the uncompressed installation files from a home directory to a system area thereby invalidating their security context. This can be addressed by a command such as....

restorecon -R -v /var/www/html/mediawiki

When all else fails, try this

man setenforce

Updating Local Policy Contexts

Changes made by using chcon are only temporary, in that they will be overwritten by any subsequent action which relabels the files (e.g. restorecon, make relabel, etc). To avoid this, you can add custom context entries to your local policy using the semanage utility. These entries are stored in a separate file, file_contexts.local, which is not part of the base SELinux policy. The entries in this file always override the entries in the base policy.

For example, the following commands will label your main wiki files as httpd_user_content_t, your PHP scripts as http_user_script_exec_t, and your images directory for uploading as httpd_user_script_rw_t:

semanage fcontext -a -t httpd_user_content_t '/path/to/mediawiki/install(/.*)?'
semanage fcontext -a -t httpd_user_script_exec_t '/path/to/mediawiki/install/.*\/php5?'
semanage fcontext -a -t httpd_user_script_exec_t '/path/to/mediawiki/install/includes/.*\.php5?'
semanage fcontext -a -t httpd_user_rw_content_t '/path/to/mediawiki/install/images(/.*)?'
semanage fcontext -a -t httpd_user_rw_content_t '/path/to/mediawiki/install/cache(/.*)?'

After running these commands, you can verify your changes by running

restorecon -R -v /path/to/mediawiki/install

References