[CentOS] SELinux prevents my PHP script from sending mail

[Alan M. Evans]

On Thu, 2012-05-03 at 06:54 -0700, Alan M. Evans wrote:
> On Thu, 2012-05-03 at 10:33 +0100, Colin Coles wrote:
> > On Wednesday 02 May 2012, Alan M. Evans wrote:
> > > Hello all...
> > > 
> > > I maintain an amateurish email list for my wife's website on my CentOS 6
> > > server. Once-a-month, she sends mail to "mylistaddr at mydomain.com" and
> > > the /etc/aliases file redirects that to my script:
> > > 
> > > mylistaddr: "| /usr/bin/php-cgi /var/www/html/mydomain/email-cgi.php"
> > > 
> > > The script, in turn, reads the recipient addresses out of a DB and
> > > composes and sends the mails. This all worked great until this month's
> > > mailing.
> > > 
> > > Now sendmail just bounces the mail back "554 5.3.0 unknown mailer error
> > > 255". When I see programs complaining about "unknown" conditions, I
> > > usually suspect SELinux first, and sure enough...
> > > 
> > > setenforce 0
> > > 
> > > then everything works like a charm. I wonder what changed between last
> > > month and this month?
> > > 
> > > Anyway, I checked the audit.log file and found the relevant AVC denials.
> > > I created a local policy (audit2allow) to circumvent the denials, which
> > > helpfully prevented the denial messages in audit.log. But the maillist
> > > script still fails identically as long as SELinux is enforcing. And now
> > > nothing shows up in audit.log.
> > > 
> > > So SELinux is preventing sendmail from calling my maillist script and
> > > not reporting the reason. How do I go about figuring out what's broken
> > > and how to fix it?
> > 
> > Do you have the httpd_can_sendmail boolean on?
> 
> Yes.

Actually, just looking at my own description and I realize that the
subject should read that SELinux is preventing my script from
*receiving* mail, not sending mail. Various scripts on the site send
mail all the time with no problem. It's the execution (via the aliases
file) of email-cgi.php that fails.

-Alan