Podman: The `podman run` command can be instructed to disable almost all sandboxing by image annotation

Impact

Podman v4.4.0 added a feature where container checkpoints (from the podman container checkpoint command) could be distributed via OCI registry, and pulled from that registry and run via the podman run command. This allowed easy transfer of checkpoints between systems. However, checkpoints allow complete control of how the container is created - including full control of the container sandbox. When podman run detects a checkpoint, it will silently ignore all user input regarding how the container should be created - for example, podman run --cap-drop=ALL on an image that is determined to be a checkpoint will ignore --cap-drop=all and use the set of capabilities specified by the checkpoint image instead, which could include all capabilities. Podman identifies checkpoint images by looking for an annotation, io.podman.annotations.checkpoint.runtime.name. If this annotation is set, the image is treated as a checkpoint. Conflating container images and checkpoints in podman run allows inherently insecure behavior as the image can now control how it is executed. The Podman Maintainers have determined that the safest course of action is to remove this functionality.

Patch

The commit introducing this functionality was reverted.

3721ff82ffb44a4ceeaecc5abd3808e924a6b669 c74b1d37b3fb834b0de43e176565d9d8c254b627 fa6cef22c2baf3987b581c673bb416ef0585daf7 (main) ea9243e04d1db3886dc3a51ee3300ffb547cfc02 450c64426dbcff1097d3c7911d791101e3d16f4c 2d05a7c61f022d4f24980ea6d307fa53da2b8692 (v6.1) 7728ba0a90094408ad9078e36c3622a651d49616 24706290d5c974f078d8ca284026802515f28e92 29c8c6e50607df7a7d735ace09ff0ea099c0b3e0 (v5.8)

Workarounds

Images being pulled should be scanned for the io.podman.annotations.checkpoint.runtime.name annotation, and rejected if it is present. Podman does not presently have the ability to perform this scanning and rejection automatically.

Also not that rootless containers are not affected as they do not support checkpoint/restore at all currently.

Credits

This vulnerability was discovered by ADA Logics Ltd using Anthropic's Claude models.