FastCGI does not work with SELinux enabled: error reading data from FastCGI server

Symptoms

PHP in FastCGI mode does not work. It seems to work properly with SELinux disabled, but it generates error  when it is in "Enforcing" state.

# getenforce
Enforcing

Apache error log files contain the following entries

In domains error log /var/www/vhosts/example.com/logs/error_log:

PLESK_INFO: [warn] [client 203.0.113.2] (104)Connection reset by peer: mod_fcgid: error reading data from FastCGI server
[error] [client 203.0.113.2] Premature end of script headers: info.php

In server wide error log /var/log/httpd/error_log:

PLESK_INFO: failed to open log file /var/log/httpd/suexec_log
fopen: Permission denied

In /var/log/httpd/suexec_log log file can be found the following error:

PLESK_INFO: [2017-08-07 23:58:46]: uid: (10004/johndoe) gid: (503/503) cmd: cgi_wrapper [2017-08-07 23:58:46]: failed to setgid (503: cgi_wrapper)

Cause

Invalid SELinux security context.

Resolution

1. Connect to the server using SSH.

2. Set the correct security context to the /usr/sbin/suexec binary

   # chcon system_u:object_r:httpd_suexec_exec_t:s0 /usr/sbin/suexec

Additional system package can be used to make this change persistent:

# yum -y install policycoreutils-python
# semanage fcontext -a -t httpd_suexec_exec_t /usr/sbin/suexec
# restorecon -Rvv /usr/sbin/suexec