SELinux policy: container_t cannot execute files labelled local_t

[sparrc]

Summary

container_t is denied execute_no_trans and entrypoint on files labelled local_t. This breaks workloads where one container writes an executable to a shared volume and another container executes it (e.g., CrowdStrike Falcon init-container pattern).

SELinux denial

{
  "scontext": "system_u:system_r:container_t:s0",
  "tcontext": "system_u:object_r:local_t:s0",
  "tclass": "file",
  "perms": ["execute_no_trans"],
  "permissive": 1,
  "pid": 1686,
  "comm": "runc:[2:INIT]"
}

A second related denial for entrypoint:

avc: denied { entrypoint } for pid=53503 comm="runc:[2:INIT]" path="/managed-agents/execute-command/amazon-ssm-agent" dev="nvme0n1p8" ino=202 scontext=system_u:system_r:container_t:s0 tcontext=system_u:object_r:s0 tclass=file permissive=0

Root cause

local_t is not included in container_exec_o:

(typeattributeset container_exec_o (data_t cache_t secret_t cni_exec_t csi_exec_t))

So the existing rule (allow container_s container_exec_o (file (entrypoint))) does not cover files labelled local_t.

Reproduction

Register an ECS Managed Instances task with two containers sharing a volume:

An init container copies a binary (e.g., /bin/sh) into the shared volume.
The application container uses that binary as its entrypoint.
The file written to the shared volume gets labelled local_t. The application container is denied execution and exits 255.

Example task definition (abbreviated):

{
  "volumes": [{"name": "shared-volume"}],
  "containerDefinitions": [
    {
      "name": "init",
      "entryPoint": ["sh", "-c"],
      "command": ["cp /bin/sh /tmp/shared/bin/run && chmod a+rx /tmp/shared/bin/run"],
      "mountPoints": [{"sourceVolume": "shared-volume", "containerPath": "/tmp/shared"}]
    },
    {
      "name": "app",
      "entryPoint": ["/tmp/shared/bin/run", "-c", "echo hello"],
      "mountPoints": [{"sourceVolume": "shared-volume", "containerPath": "/tmp/shared", "readOnly": true}],
      "dependsOn": [{"containerName": "init", "condition": "COMPLETE"}]
    }
  ]
}

Suggested fix

Add local_t to container_exec_o, or add a standalone rule:

(allow container_s local_t (file (entrypoint)))