Php has its own /tmp in /tmp/systemd-private-nABCDE/tmp when accessed through nginx

Question

I found strange behaviour concerning php and /tmp folder. Php uses another folder when it works with /tmp. Php 5.6.7, nginx, php-fpm.

I execute the same script in two ways: via browser and via shell. But when it is launched via browser, file is not in real /tmp folder:

<?php
$name = date("His");

echo "File /tmp/$name.txt\n";

shell_exec('echo "123" > /tmp/'.$name.'.txt');

var_dump(file_exists('/tmp/'.$name.'.txt'));

var_dump(shell_exec('cat /etc/*release | tail -n 1'));

php -f script.php

File /tmp/185617.txt
bool(true)
string(38) "CentOS Linux release 7.0.1406 (Core)

Where is the file? In /tmp

$ find / -name 185617.txt
/tmp/185617.txt

If access it via http://myserver.ru/script.php I get

File /tmp/185212.txt
bool(true)
string(38) "CentOS Linux release 7.0.1406 (Core)

But where is the file?

$ find / -name 185212.txt
/tmp/systemd-private-nABCDE/tmp/185212.txt

Why does php thinks that /tmp should be in /tmp/systemd-private-nABCDE/tmp?

Ignacio Vazquez-Abrams · Accepted Answer · 2015-05-25 20:13:07Z

44

Because systemd is configured to give nginx a private /tmp. If you must use the system /tmp instead for some reason then you will need to modify the .service file to read "PrivateTmp=no".

answered May 25, 2015 at 20:13

Ignacio Vazquez-Abrams

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5 Comments

shukshin.ivan Over a year ago

You are right, but that's php-fpm, not nginx. I changed file /usr/lib/systemd/system/php-fpm.service line PrivateTmp=true into PrivateTmp=false. Now php uses correct /tmp folder.

Milan Maharjan Over a year ago

wow this is brilliant. right what we were searching since 2 days :)

Gerben Over a year ago

Do consider the security implications of this change. /tmp may contain sensitive information and all php-scripts can suddenly access that information.

Scott Over a year ago

What if your system does not have the system sub folder? might it be somewhere else?

domdambrogia Over a year ago

@Scott find / -type f -name 'php-fpm.service'. You'll need to run that as sudo/root most likely but it will recursively located any file starting from the root (/) directory that is named php-fpm.service.

Artis · Accepted Answer · 2017-03-20 16:24:49Z

2

If you are running multiple sites on the server then I think you'll want to leave PrivateTmp=yes so that each site remains segregated even in it's use of temp files. Could be a security issue otherwise, I'd imagine.

answered Mar 20, 2017 at 16:24

Artis

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Comments

Benjamin · Accepted Answer · 2019-09-06 18:36:25Z

0

Ignacio Vazquez-Abrams have the correct answer, but let me add my functional solution.

I've try "multi-user.target.wants" solution, it have worked but after restart, but at some point, PrivateTmp go back to true. Like my principal use of Apache2 is PHP, I finally edited php.ini and I've uncomment line sys_temp_dir.

By default system use temp dir assigned by function sys_get_temp_dir. Function sys_get_temp_dir will return "/tmp" but the truth is that your tmp files are storing at some path like /tmp/systemd-private-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX-apache2.service-YYYYYY//tmp/*. So, what work for me was:

Edit php.ini (path can change between PHP versions)

sudo nano /etc/php/7.2/cli/php.ini

Then uncomment sys_temp_dir line

; Directory where the temporary files should be placed.
; Defaults to the system default (see sys_get_temp_dir)
sys_temp_dir = "/tmp"

edited Sep 6, 2019 at 18:36

answered Sep 6, 2019 at 18:28

Benjamin

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1 Comment

stackprotector Over a year ago

The XXX can be read from /proc/sys/kernel/random/boot_id but from where do you get YYY?

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