podman-security-basics

name	podman-security-basics
description	Authorized Podman security hardening and assessment: rootless vs rootful, user namespaces, capabilities, SELinux labels, privileged/host mounts, publish ports, Podman socket exposure, secrets, and image trust. Use when reviewing Containerfile runtime, podman run/quadlet/kube YAML, rootful daemon risks, or lab/org Podman stacks you own — not for attacking third-party hosts.

Podman Security Basics

Assess and harden Podman (and Quadlet/systemd units) so containers do not gain host-equivalent power, expose sockets, or ship secrets. Defensive and authorized only. Daemonless/rootless still fails open under bad mounts or sockets.

Scope And Authorization

• In scope: Podman installs, containers, pods, volumes, Quadlet units, and Compose-compatible files you own or are contracted to review; lab/CTF; read-only podman inspect under written engagement.
• Out of scope: Escaping shared multi-tenant hosts without approval; abusing third-party Podman/Docker sockets; destructive demos on production.
• Prefer inspect/config review before privilege experiments. Gate breakout proofs to lab hosts (container-escape-techniques).
• Redact registry tokens, pull secrets, SSH keys in mounts, and customer hostnames.
• Image build → dockerfile-best-practices. Compose-shaped YAML → also docker-compose-security where syntax overlaps.

When To Use

• Reviewing podman run, Quadlet .container/.kube, podman play kube, or Podman Compose / Docker Compose on Podman
• Rootful Podman, privileged, host PID/IPC/net, broad cap_add, unconfined seccomp/AppArmor/SELinux
• Sensitive binds (/, /etc, home, keys) or Podman/Docker socket
• Rootless UID maps, SELinux :Z/:z labels, or publish on 0.0.0.0
• Secrets in env/CLI history; floating/latest tags in prod
• Keywords: Podman security, rootless, podman.sock, quadlet, SELinux volume

Do not use as primary for:

Need	Skill instead
Containerfile multi-stage / non-root USER	dockerfile-best-practices
Compose ports/secrets/sock patterns	docker-compose-security
Lab container→host breakout	container-escape-techniques
K8s cluster RBAC (not Podman host)	kubernetes-pentesting
cosign/sigstore trust policy	container-image-signing
Scripts/units quality; secret rotation	code-quality-standards, secrets-management-hygiene

Workflow

1. Inventory runtime and trust model

1. Record version, rootless vs rootful (podman info), cgroup/storage, and whether podman.socket / Docker-compat socket is enabled.
2. List containers, pods, networks, volumes, Quadlet under /etc/containers/systemd or ~/.config/containers/systemd.
3. Map public publishes vs internal services; note registry auth.

Output: inventory with owners — no tokens or private keys.

2. Rootless vs rootful

Mode	Expectation
Rootless	Prefer for apps; verify subuid/subgid ranges
Rootful	Justify; treat like privileged-daemon risk
Socket API	podman.socket / docker.sock-compat ≈ host power for that user

Rootless is not full isolation (kernel bugs, weak mounts). Document mandatory rootful cases (devices, some CNI) and lock those hosts tightly.

3. Privilege and isolation

Per service (podman inspect / Quadlet): no privileged unless node-agent with owner+expiry; drop caps (no ALL); keep default seccomp/SELinux; avoid pid/ipc/uts/network=host for apps; non-root USER; justify devices and --security-opt label=disable.

4. Mounts, labels, and socket

Mount / option	Guidance
Podman/Docker socket	Host-equivalent — never on untrusted apps
Host /, /etc, storage root	Deny by default
Credential volumes	:ro + host 0600; SELinux :Z private vs :z shared
Masked paths	Keep defaults; do not unmask sensitive /proc/sys

5. Network publish and secrets

1. Prefer 127.0.0.1:port:port for admin/debug; avoid bare publishes for DB/admin.
2. User-defined networks; do not publish backends that only need inter-container traffic.
3. No passwords in -e, committed env, or shell history; prefer podman secret / secrets store (secrets-management-hygiene).
4. Pin digests/tags; avoid prod latest; signed/mirrored images when policy requires (container-image-signing).

6. Verify and remediate

Re-inspect options/publishes; confirm admin ports not world-reachable from an approved vantage; apply code-quality-standards to Quadlet/scripts/CI; prove exposure from config — do not demo host compromise on shared prod.

Routing

Situation	Primary	Helper
Podman rootless/rootful, caps, SELinux, sock, publish	This skill	—
Image non-root / layer secrets	dockerfile-best-practices	this for runtime
Compose YAML (Docker or Podman Compose)	docker-compose-security	this for Podman-specific
Lab breakout (sock/privileged/cgroup)	container-escape-techniques	this for evidence
Image signature / trust policy	container-image-signing	this for pins
Secret lifecycle; scripts/CI quality	secrets-management-hygiene, code-quality-standards	this for paths/intent

Output Checklist

• Scope/authorization clear; no out-of-scope host or socket abuse
• Rootless vs rootful, version, socket exposure inventoried
• No unjustified privileged / host namespaces / unconfined labels
• Caps minimized; non-root inside containers where supported
• No Podman/Docker socket or sensitive host mounts on app services
• Volume SELinux labels and :ro used appropriately
• Publishes intentional; admin/DB not on all interfaces without exception
• Secrets not in VCS/CLI; podman secret or external store used
• Images pinned; signing/mirror policy followed when required
• Fixes follow code-quality-standards; residuals owned with expiry
• Escape claims only via container-escape-techniques in lab

Rules

• Socket access and privileged are critical, not style nits.
• Prefer rootless + least publish + least capability; secrets out of VCS.
• Authorized org/lab only; evidence from inspect/config, not destructive demos.
• Review image and runtime — hardened images are undone by bad Quadlet/run flags.