ImageMagick security policy 'PDF' blocking conversion
LinuxUbuntuPdfImagemagickImagemagick ConvertLinux Problem Overview
The Imagemagick security policy seems to be not allowing me perform this conversion from pdf to png. Converting other extensions seem to be working, just not from pdf. I haven't changed any of the imagemagick settings since I installed it... I am using Arch Linux, if the OS matters.
user@machine $ convert -density 300 -depth 8 -quality 90 input.pdf output.png
convert: attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/408.
convert: no images defined `output.png' @ error/convert.c/ConvertImageCommand/3288.
Linux Solutions
Solution 1 - Linux
Well, I added
<policy domain="coder" rights="read | write" pattern="PDF" />
just before </policymap>
in /etc/ImageMagick-7/policy.xml
and that makes it work again, but not sure about the security implications of that.
Solution 2 - Linux
This issue is a workaround for a security vulnerability. The vulnerability has been addressed in Ghostscript 9.24 (source), so if you have that or a newer version, you don't need the workaround anymore.
On Ubuntu 19.04 through 21.04 and probably any later versions coming with ImageMagick 6, here's how you fix the issue by removing the workaround:
-
Make sure you have Ghostscript ≥9.24:
gs --version
-
If yes, just remove this whole following section from
/etc/ImageMagick-6/policy.xml
:<!-- disable ghostscript format types --> <policy domain="coder" rights="none" pattern="PS" /> <policy domain="coder" rights="none" pattern="PS2" /> <policy domain="coder" rights="none" pattern="PS3" /> <policy domain="coder" rights="none" pattern="EPS" /> <policy domain="coder" rights="none" pattern="PDF" /> <policy domain="coder" rights="none" pattern="XPS" />
Solution 3 - Linux
As pointed out in some comments, you need to edit the policies of ImageMagick in /etc/ImageMagick-7/policy.xml
. More particularly, in ArchLinux at the time of writing (05/01/2019) the following line is uncommented:
<policy domain="coder" rights="none" pattern="{PS,PS2,PS3,EPS,PDF,XPS}" />
Just wrap it between <!--
and -->
to comment it, and pdf conversion should work again.
Solution 4 - Linux
For me on Arch Linux, I had to comment this:
<policy domain="delegate" rights="none" pattern="gs" />
Solution 5 - Linux
For me on my archlinux system the line
Solution 6 - Linux
Works in Ubuntu 20.04
Add this line inside <policymap>
<policy domain="module" rights="read|write" pattern="{PS,PDF,XPS}" />
Comment these lines:
<!--
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="PS2" />
<policy domain="coder" rights="none" pattern="PS3" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="none" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />
-->
Solution 7 - Linux
The ImageMagick change was kept after Ghostscript was fixed because applications (especially web applications) often feed arbitrary user-supplied files to ImageMagick, don't always enforce format restrictions properly, and, since Postscript (which PDF uses) is a turing-complete programming language running in a sandbox, there's always the possibility of another hole in the sandbox.
It's much better to leave things configured so ImageMagick refuses to process files that require running a program and, instead, just invoke Ghostscript directly when you intentionally want to permit Postscript rendering.
That would be accomplished by a Ghostscript command like this:
gs -dSAFER -r600 -sDEVICE=pngalpha -o foo.png myfile.pdf
Yes, this is a variation on the GhostScript command ImageMagic calls. (see ImageMagick's delegates.xml
. -o
is shorthand for -dBATCH -dNOPAUSE -sOutputFile=
)
What's important is that ImageMagick stays locked down, you don't needlessly invoke an intermediate program, and you get more control over the rendering parameters. (eg. -r600
is the DPI to render at and changing -sDEVICE=pngalpha
allows you to render directly to your desired format)
Solution 8 - Linux
As a highly active comment by @Richard Kiefer, a simple fix is like this
$ sudo sed -i '/disable ghostscript format types/,+6d' /etc/ImageMagick-6/policy.xml
Solution 9 - Linux
On Ubuntu 19.10, I have done this in /etc/ImageMagick-6/policy.xml
uncomment this
<policy domain="module" rights="read | write" pattern="{PS,PDF,XPS}" />
and comment this
<!-- <policy domain="coder" rights="none" pattern="PDF" /> -->
After that, this command work without error
convert -thumbnail x300 -background white -alpha remove sample.pdf sample.png
Solution 10 - Linux
Adding to Stefan Seidel's answer.
Well, at least in Ubuntu 20.04.2 LTS or maybe in other versions you can't really edit the policy.xml file directly in a GUI way. Here is a terminal way to edit it.
-
Open the policy.xml file in terminal by entering this command -
sudo nano /etc/ImageMagick-6/policy.xml
-
Now, directly edit the file in terminal, find
<policy domain="coder" rights="none" pattern="PDF" />
and replacenone
withread|write
as shown in the picture. Then press Ctrl+X to exit.
Solution 11 - Linux
I was experiencing this issue with nextcloud which would fail to create thumbnails for pdf files.
However, none of the suggested steps would solve the issue for me.
Eventually I found the reason: The accepted answer did work but I had to also restart php-fpm after editing the policy.xml file:
sudo systemctl restart php7.2-fpm.service
Solution 12 - Linux
Manjaro April 2021
Just remove uncommented line inside <policymap>
in /etc/ImageMagick-7/policy.xml
Solution 13 - Linux
In my case i'm useing ubuntu 20.10 and the Imagick-7.
in my /etc/ImageMagick-6/policy.xml I've removed below lines, restarted my machine and I'm done.
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="PS2" />
<policy domain="coder" rights="none" pattern="PS3" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="none" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />