hyperhive/hive-priv
Repository files (latest commit first)
Filename Latest commit message Latest commit date
atlas 258c0998ab test(#2862): cover both fd/op mismatch branches in hive-priv
check_fd_agreement is the guard that keeps a descriptor and the request
it arrived with in agreement, and both of its rejections were untested.

An fd-taking op with no descriptor must not fall back to anything: a
temp file or the response socket would send an agent's state somewhere
the caller never asked for. The mirror case matters for a different
reason -- returning the error is what drops the OwnedFd and closes it,
so ignoring a stray descriptor instead would leak one per bad request
in a long-lived root process.

The third test pins both agreeing combinations, so the check is
rejecting mismatches rather than descriptors in general. Descriptors
are real /dev/null handles so the closing drop is genuinely exercised.
2026-07-31 22:15:37 +02:00
..
src test(#2862): cover both fd/op mismatch branches in hive-priv 2026-07-31 22:15:37 +02:00
Cargo.toml docs(#2627): add READMEs for the remaining infra crates 2026-07-23 13:16:29 +02:00
README.md docs(#2627): add READMEs for the remaining infra crates 2026-07-23 13:16:29 +02:00

hive-priv

The minimal root privileged-helper for hive-c0re. It runs as root and exposes a narrow unix socket at /run/hive/priv.sock that accepts PrivRequest JSON lines and performs only the handful of operations that genuinely require root — bind-mount edits, nsenter into a container, btrfs subvolume ops. All coordination logic (broker, HTTP, scheduling) stays in the unprivileged hive-c0re process, which delegates here.

Why it exists

Privsep. hive-c0re runs as the unprivileged hive-core user so a bug or a prompt-injection in the large daemon can't directly wield root. The few root operations it needs are funnelled through this small, auditable helper instead. See docs/boundary.md and docs/security.md for the privilege boundary.

Security model

  • Strict allowlist. Every request is validated against a container-name allowlist before any filesystem or process operation — only names matching the hive convention (h-*, the manager container, known sibling service containers) are accepted.
  • No pass-through. Every PrivRequest variant maps to a single known operation; there is no arbitrary-command escape hatch.
  • Socket-activated, always. systemd binds /run/hive/priv.sock (SocketGroup=hive-core, 0660) and passes the listener as fd 3 (LISTEN_FDS); the helper requires this and has no self-bind fallback, so dev and prod take the identical path and the group grant always holds.

The wire contract (PrivRequest / response types) lives in the separate hive-priv-sock crate so this root binary depends on just the protocol shapes, not the whole daemon-shared crate.