PHP is_writable() function always returns false fo

I'm trying to install a PHP-based software package in a Red Hat 7 Amazon EC2 instance (ami-8cff51fb) that has had Apache 2.4.6 and PHP 5.4.16 installed on it using yum. The installation fails because it says a particular directory needs to be writable by the webserver with 0755 or 0775 permissions.

The directory in question has 0775 permissions with root:apache ownership. I have verified that the httpd process is being run by the apache user and that the apache user is a member of the apache group.

If I edit /etc/passwd to temporarily give the apache user a login shell and then su to that account, I am able to manually create files as the apache user within the directory using the touch command.

I took a look at the source code of the installer script and identified that it's failing because PHP's is_writable() function is returning false for the directory in question. I created a separate test PHP script to isolate and verify the behaviour I'm seeing:

<?php
  $dir = '/var/www/html/limesurvey/tmp';
  if (is_writable($dir)) {
    echo $dir, ' is writable';
  } else {
    echo $dir, ' is NOT writable';
  }
?>

This outputs the NOT writable message. If I change $dir above to be /tmp then it correctly outputs that /tmp is writable.

If I change the directory permissions to 0777 and/or change the ownership to apache:apache then PHP still reports that the directory isn't writable. I even tried creating a /test directory set up with the same permissions and ownership and my test script still reports it as not writable.

I'm really at a loss as to explain this behaviour, so any ideas would be welcome!

Thanks in advance.

The directory listing for /var/www/html/limesurvey is given below. The tmp and upload directories have 0775 permissions as per Lime Survey's installation instructions. test.php is my test script mentioned above.

[ec2-user@ip-xx-x-x-xxx limesurvey]$ pwd
/var/www/html/limesurvey
[ec2-user@ip-xx-x-x-xxx limesurvey]$ ls -al
total 80
drwxr-xr-x. 20 root apache 4096 Mar 30 11:25 .
drwxr-xr-x.  3 root root     23 Mar 25 14:41 ..
drwxr-xr-x.  2 root apache   38 Mar 10 12:56 admin
drwxr-xr-x. 16 root apache 4096 Mar 10 12:56 application
drwxr-xr-x.  3 root apache 4096 Mar 10 12:56 docs
drwxr-xr-x.  2 root apache 4096 Mar 10 12:56 fonts
drwxr-xr-x. 19 root apache 4096 Mar 10 12:56 framework
-rw-r--r--.  1 root apache  429 Mar 10 12:56 .gitattributes
-rw-r--r--.  1 root apache  399 Mar 10 12:56 .gitignore
-rw-r--r--.  1 root apache  296 Mar 10 12:56 .htaccess
drwxr-xr-x.  4 root apache 4096 Mar 10 12:56 images
-rw-r--r--.  1 root apache 6652 Mar 10 12:56 index.php
drwxr-xr-x.  5 root apache   39 Mar 10 12:56 installer
drwxr-xr-x. 89 root apache 4096 Mar 10 12:56 locale
drwxrwxr-x.  2 root apache   39 Mar 25 14:41 logs
drwxr-xr-x.  4 root apache   49 Mar 10 12:56 plugins
-rw-r--r--.  1 root apache   61 Mar 10 12:56 README
drwxr-xr-x.  4 root apache 4096 Mar 10 12:56 scripts
-rw-r--r--.  1 root apache  380 Mar 10 12:56 .scrutinizer.yml
drwxr-xr-x.  5 root apache 4096 Mar 10 12:56 styles
drwxr-xr-x.  5 root apache 4096 Mar 10 12:56 styles-public
drwxr-xr-x. 12 root apache 4096 Mar 10 12:56 templates
-rw-r--r--.  1 root apache  159 Mar 30 11:11 test.php
drwxr-xr-x.  3 root apache   20 Mar 10 12:56 themes
drwxr-xr-x. 26 root apache 4096 Mar 10 12:56 third_party
drwxrwxr-x.  5 root apache   80 Mar 26 13:45 tmp
drwxrwxr-x.  6 root apache   79 Mar 10 12:57 upload

Running namei -l /var/www/html/limesurvey/tmp gives:

[ec2-user@ip-x-x-x-xxx ~]$ namei -l /var/www/html/limesurvey/tmp
f: /var/www/html/limesurvey/tmp
drwxr-xr-x root root   /
drwxr-xr-x root root   var
drwxr-xr-x root root   www
drwxr-xr-x root root   html
drwxr-xr-x root apache limesurvey
drwxrwxr-x root apache tmp

回答1:

After much head-scratching, it transpired that SELinux was preventing the directory from being written to. I found a good tutorial that explains what's going on. I was able to fix it by running this command:

sudo chcon -R -t httpd_sys_rw_content_t tmp

回答2:

in CentOS 6 above should be SELinux enable enforcing

setenforce Permissive

check the status

sestatus

refer to https://wiki.centos.org/HowTos/SELinux

回答3:

to write to a directory you also need execute permissions to the dirs above.

namei -l /var/www/html/limesurvey/tmp

should show which step you do not have the correct permissions for.

回答4:

HTTPDUSER=`ps aux | grep -E '[a]pache|[h]ttpd|[_]www|[w]ww-data|[n]ginx' | grep -v root | head -1 | cut -d\  -f1`
sudo setfacl -R -m u:"$HTTPDUSER":rwX -m u:`whoami`:rwX tmp
sudo setfacl -dR -m u:"$HTTPDUSER":rwX -m u:`whoami`:rwX tmp

Taken directly from the Symfony2 installation guide, this solves the problem with cache write access sharing between Apache and CLI tools. This might work for your tmp directory as well.

回答5:

is_writable by default only checks on the user, not the group. So even if you group is matching and has permissions is_writable will return false. To relax this check you will need to set