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fix(imagecache): keep the owner an image layer gives its files - #115
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atelet unpacks layers with every capability dropped, so every file it writes belongs to root whatever the layer tar says. An actor that runs as its image's USER could not write what its image gave it: an image that creates a directory for its user saw it owned by root. atelet now records the tar's non-root owners in the layer metadata, with the setuid and setgid bits a chown clears, and ateom's FinalizeLayer applies them to the pooled layer tree once per layer node-wide, under a marker of its own. The merged rootfs presents them without copying anything up. A layer pooled before owners were recorded is backfilled from its tar headers the next time a pull reuses it. Signed-off-by: QuentinBisson <quentin@giantswarm.io>
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QuentinBisson
marked this pull request as ready for review
October 5, 2026 07:24
This was referenced Oct 5, 2026
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Problem
atelet unpacks image layers with every capability dropped, so every image-layer file is root's whatever the tar says (agent-substrate#2036). With #103 an actor runs as its image's
USER, and such a user cannot write what its image gave it: kagent's Go ADK golden boot fails withopen /config/config.json: permission deniedon 1.4.0-rc.2 (giantswarm/kagent-upstream#125).Change
atelet records the tar's non-root owners (with the setuid/setgid bits a chown clears) in the layer metadata; ateom's
FinalizeLayerapplies them to the pooled layer tree once per layer node-wide under its ownowners-appliedmarker, so the merged rootfs presents them with no copy-up. A layer pooled before this is backfilled from its tar headers when a pull reuses it. Written for upstream against agent-substrate#2036, which agent-substrate#1918 needs before it merges.Towards giantswarm/giantswarm#38054