[pdf] ImageMagick security policy 'PDF' blocking conversion

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.

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.

1. Open the policy.xml file in terminal by entering this command -

   sudo nano /etc/ImageMagick-6/policy.xml

2. Now, directly edit the file in terminal, find <policy domain="coder" rights="none" pattern="PDF" /> and replace none with read|write as shown in the picture. Then press Ctrl+X to exit.

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" />
   -->

Alternatively you can use img2pdf to convert images to pdf. Install it on Debian or Ubuntu with:

sudo apt install img2pdf

Convert one or more images to pdf:

img2pdf img.jpg -o output.pdf

It uses a different mechanism than imagemagick to embed the image into the pdf. When possible Img2pdf embeds the image directly into the pdf, without decoding and recoding the image.

For me on my archlinux system the line was already uncommented. I had to replace "none" by "read | write " to make it work.

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.

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

For me on Arch Linux, I had to comment this:

  <policy domain="delegate" rights="none" pattern="gs" />

This is due to a security vulnerability that has been addressed in Ghostscript 9.24 (source). If you have a newer version, you don't need this workaround anymore. On Ubuntu 19.10 with Ghostscript 6, this means:

1. Make sure you have Ghostscript =9.24:

   gs --version
   

2. 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" />
   

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