Enable SVG decode via librsvg, read-only

CHANGES.md

@@ -4,6 +4,7 @@
 
 ### Add
 
+* SVG decode support for ImageMagick. `imagemagick-svg` (the librsvg-backed coder) is now installed, and the hardened policy grants the `SVG`/`SVGZ` coders read-only rights so Imagick can rasterize SVG uploads for preview transformations. The guards that made SVG worth blocking stay in force: HTTP/HTTPS delegates and `@*` path reads remain denied (no external hrefs, no local file leaks), `MSVG` — ImageMagick's internal, riskier SVG renderer — stays blocked so it cannot be reached even if librsvg goes missing, and SVG encode is still denied. The policy install step now decodes a probe SVG so the build fails loudly if SVG support regresses, and structure tests assert the delegate, the read-only policy pairing, and a real decode.
 * Weekly dependency automation (`.github/workflows/dependencies.yml`). A scheduled job resolves the newest upstream release for every pinned Dockerfile source, rewrites the pins, opens a pull request, waits for the exact CI runs for that head, approves and merges it, then tags, builds, and publishes the release. A `recover` step resumes a run that died between merge and publish, so a half-finished release is completed rather than duplicated.
 * PHP automation domain under `.github/scripts` — `Dependency` (catalog, resolvers, Dockerfile pin rewriting, reporting), `Automation` (release orchestration, version selection, merge and target validation, recovery), `Command`, and `Parity`. Entry points are `bin/dependencies.php`, `bin/orchestrator.php`, and `bin/parity.php`.
 * Composer tooling for the automation: `lint` (Pint), `check` (PHPStan), `test` (PHPUnit), `parity` (asserts every source class has covering tests), and `verify` to run all four. CI runs `composer verify` before touching any dependency.

Dockerfile

@@ -267,6 +267,7 @@ RUN apk update && \
     icu-libs \
     imagemagick \
     imagemagick-heic \
+    imagemagick-svg \
     libavif \
     libgomp \
     libheif \
@@ -294,7 +295,10 @@ RUN set -eux; \
     POLICY_DIR="$(identify -list configure | awk '/^CONFIGURE_PATH/ {print $2}' | cut -d: -f1)"; \
     cp /tmp/policy.xml "${POLICY_DIR%/}/policy.xml"; \
     rm /tmp/policy.xml; \
-    identify -list policy | grep -q '50KP'
+    identify -list policy | grep -q '50KP'; \
+    printf '<svg xmlns="http://www.w3.org/2000/svg" width="8" height="8"/>' > /tmp/probe.svg; \
+    identify /tmp/probe.svg; \
+    rm /tmp/probe.svg
 
 WORKDIR /usr/src/code
 

policy.xml

@@ -23,7 +23,7 @@
   allocated, and disk caps the pixel-cache spill. memory/map/area merely change
   when the cache moves to disk. All values are tunable.
 
-  Preview inputs are limited to JPEG, PNG, HEIC, WEBP and GIF (output adds
+  Preview inputs are limited to JPEG, PNG, HEIC, WEBP, GIF and SVG (output adds
   AVIF), so the delegate coders disabled below are never used and only add risk.
   Validate changes with https://imagemagick-secevaluator.doyensec.com/.
 -->
@@ -60,13 +60,16 @@
   <policy domain="delegate" rights="none" pattern="HTTPS"/>
   <policy domain="delegate" rights="none" pattern="HTTP"/>
   <policy domain="coder" rights="none" pattern="{PS,PS2,PS3,EPS,EPI,EPT,EPSF,EPSI,PDF,XPS}"/>
-  <policy domain="coder" rights="none" pattern="{MSL,MVG,SVG,SVGZ,MSVG,TEXT,LABEL,CAPTION}"/>
+  <policy domain="coder" rights="none" pattern="{MSL,MVG,MSVG,TEXT,LABEL,CAPTION}"/>
   <policy domain="coder" rights="none" pattern="{URL,FTP,EPHEMERAL,MPEG,MPG}"/>
 
-  <!-- SVG is an SSRF/XXE vector (its renderer resolves external hrefs and
-       entities) and is never a preview input. The module deny also closes the
-       delegate route (e.g. rsvg), which a plain coder deny does not. -->
-  <policy domain="module" rights="none" pattern="{SVG,MSVG,SVGZ}"/>
+  <!-- SVG previews decode via librsvg (imagemagick-svg), read-only - nothing
+       encodes SVG. SVG is historically an SSRF/XXE vector, so the guards
+       around it stay load-bearing: the HTTP/HTTPS delegate denies block
+       external hrefs, the @* path deny below blocks local file reads, and
+       MSVG stays denied above so ImageMagick's internal SVG renderer (the
+       riskier fallback) cannot be reached even if librsvg goes missing. -->
+  <policy domain="coder" rights="read" pattern="{SVG,SVGZ}"/>
 
   <!-- Block indirect reads (e.g. @file, caption:@file) that can leak local files. -->
   <policy domain="path" rights="none" pattern="@*"/>

tests.yaml

@@ -102,6 +102,7 @@ commandTests:
     args: ["-i"]
     expectedOutput:
       - "ImageMagick supported formats .*WEBP.*"
+      - "ImageMagick supported formats .*SVG.*"
   - name: 'ImageMagick hardened policy loaded'
     command: "identify"
     args: ["-list", "policy"]
@@ -110,6 +111,11 @@ commandTests:
       - "name: height"
       - "name: disk"
       - "50KP"
+      - "rights: Read\\s+pattern: \\{SVG,SVGZ\\}"
+  - name: 'ImageMagick SVG decode'
+    command: "php"
+    args: ["-r", "$i = new Imagick(); $i->readImageBlob('<svg xmlns=\"http://www.w3.org/2000/svg\" width=\"8\" height=\"8\"/>'); print($i->getImageWidth());"]
+    expectedOutput: ["8"]
   - name: 'PHP intl'
     command: "php"
     args: ["-r", 'print(\Normalizer::FORM_D);']