Re: php 5.6 on CentOS 6

Valeri Galtsev <galtsev@xxxxxxxxxxxxxxxxx> · Sun, 21 Jun 2020 20:02:04 -0500

On 6/21/20 5:58 PM, Jonathan Billings wrote:

On Jun 21, 2020, at 16:38, Valeri Galtsev <galtsev@xxxxxxxxxxxxxxxxx> wrote:
This my reply is not intended for the OP, as he stated he will not listen about End Of Life of of PHP 5. Just in case anybody comes across this thread, please read what is written on the page referred to by Alexander Dalloz:

PHP 5.6 is EOL. https://www.php.net/supported-versions.php

If you are using the packages PHP packages in CentOS and keep your OS up to date, you can disregard this.

This in plain English language says that php 5 is not supported by vendor since Jan 1 2019, i.e. almost a year a a half now. This means that PHP development team does not release security patches, and even though RedHat "backports" patches to older versions, difference in internals between PHP version 5 and version 7 is quite significant, so you should not assume that even if RedHat team still backports security patches for issues discovered in version 7, you are safe: there may be still be issues in version 5 which by no means are discovered by anyone.

This boils down to one thing. If you still have anything using PHP version 5.[any] you should migrate this to PHP version at least 7.2. You ideally should have done that before Jan. 1, 2019.
I hope, this helps somebody.

By no means I meant to question the brilliant job RedHat does backporting (taking my hat off and bowing to RedHat here). However, as I said, there may be bugs in PHP 5 that will not be relevant to PHP 7, hence there is nothing to backport to fix them.

I realize you are out of touch with how CentOS packages (and RHEL packages they’re built from) are handled, since you’ve decided to stop using it and move to FreeBSD, but this is how Red Hat backports fixes to php and other enterprise software:

https://access.redhat.com/security/updates/backporting

Apparently, I didn't manage to make myself clear enough, so you even 
think I have no idea about how RedHat backports fixes work. You gave the 
reference, when I read your first phrase, I was going to refer to a 
backporting page, but here you just gave that same URL:

https://access.redhat.com/security/updates/backporting/

Of course, my knowledge is not full and extremely precise, but I have 
decent idea of how it works, known it for years, and that was basis of 
my choice: CentOS, not a "rolling release" distribution like Debian. I 
will reiterate it in general, as I will attempt to base on it the 
case... but that will be later.

1. RedHat chooses some version of some software [forget here the reason 
why that specific version], say, PHP 5.3, and does the best to keep that 
patched and secure for as long as they feel practical

2. When PHP project moves on and stops updating 5.3, RedHat analyzes 
what new release fixes, ports these fixes back to version 5.3, analyzes 
patches PHP releases to new versions, and sees whether these patches are 
relevant to code in version 5.3, and ports fixes to 5.3 version.

3. When PHP moves to higher version, say, 7 but still maintains version 
5, RedHat does the same as in 2. However, once version 5 is EOL, PHP 
project stops patching version 5. However, version 7 shares quite 
significant portion of code with version 5. So, once patch (or minor 
release fixing some things) of PHP 7 comes, RedHat again analyzes 
whether fixes are relevant to older version RedHat still maintains, it 
will most likely be version 5.6 now. Occasionally, with life cycle as 
long as 10 years, RedHat has to jump forward with minor version number 
skipping a few, it may be jump from 5.3 to 5.6, don't catch me not 
citing exact version numbers.

That is in general brilliant and rather effort consuming way RedHat 
manages to keep for quite long pretty much the same environment, thus 
allowing those who use it to not constantly adjust their code to ever 
moving, say, PHP, as opposed to Debian and clones, or BSD descendants 
(in whose cases PHP 5.6 EOL, you better have all ported to PHP 7 now). 
And we did not even mention that RedHat audits some code also, so things 
are even better.

However, in this excellent picture there is one piece that is not 
covered. I know, the likelihood of what I will describe below in small, 
but it is not zero, not excluded.

First: how weaknesses and bugs are discovered? Mostly by:

A. User (I am including sysadmin running servers in such) discover 
something broken, not working as expected, and files bug report or PR 
(problem report is what some projects call it).

B. Several big guys, like Amazon, Google, ... have people auditing 
important for them parts of code, and file bug reports, and often even 
patches to fix it

C. Several agencies sometimes do their auditing (CERT comes to my mind, 
someone may extend the list)

If something is not discovered, no one will work on fixing it. But it 
still may represent danger, even though bad guys usually hunt after 
known stuff.

Now, that PHP 5.6 EOL came year and a half ago, majority of "rolling" 
distributions (Debian and clones, FreeBSD, etc...) and people who use 
them switched over to version 7. Part of RedHat userbase did the same. 
As a consequence, PHP 5.6 has really slim userbase at this moment, so A. 
- user - is much less likely to find unknown problems. Big guys as in B. 
have decently powerful programmer teams, or enough money to hire someone 
who will rewrite code, so they most likely abandoned version 5.6 
practically. Agencies aimed purely at security as in C. are quite likely 
considering version 5.6 lowest priority.

This should hopefully explain that PHP version 5.6, even patched by 
doing its best RedHat still may have undiscovered and not fixed bugs 
with security implications. One can argue, the probability of that is 
low. But there is no way to prove that there are none, the same as one 
can not prove an opposite.

I hope, this is more clear than my original short comment.

Valeri

So if someone is coming across this thread, know that if you are using the supported PHP packages in CentOS’s repositories, security fixes are backported, and if security issues are identified in the version in RHEL, they’ll issues fixes during the lifetime of the release.  So, in CentOS 7, expect the php 5 packages to be supported for a couple more years, despite all the gnashing off teeth of the PHP upstream developers.

If you plan on starting a new project, definitely start with php 7.  But if you have concerns about an existing 5.x codebase, as long as you are keeping your OS up to date, you have some time to migrate.

--
Jonathan Billings
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--
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
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