| Filename | Latest commit message | Latest commit date |
|---|---|---|
51f352f0ca
hive-priv read requests with BufReader::lines, which cannot surface SCM_RIGHTS: ancillary data is attached to one specific recvmsg call, so a buffered line reader takes the bytes and silently drops the descriptor. Replace it with a recvmsg loop. The pairing is deliberately trivial. hive-sock-client connects per request, so a connection carries one line and at most one descriptor; a second descriptor arriving before its line is a protocol error rather than something to queue. check_fd_agreement rejects both mismatches -- an fd-taking op that got none, and a descriptor sent to an op that takes none -- and dropping the OwnedFd on that path closes it. recv_with_fds claims every descriptor the kernel attaches, including ones this protocol never expects, because an fd we fail to claim leaks for the life of the process. MSG_CMSG_CLOEXEC keeps a received descriptor out of every btrfs and nixos-container child. The control buffer is only cmsghdr-aligned, so descriptors are copied out byte-wise instead of read through a more strictly aligned pointer. SendAgentSnapshotToFd is SendAgentSnapshotToFile without the staging file: same validation and -p parent handling, stdout wired to the passed descriptor. It exists so hive-c0re can connect to a peer hive's snapshot store, write the header itself, and hand over the connected socket -- leaving this helper with no address, no protocol, and nobody in the data path once the send starts. |
||
| .. | ||
| src | ||
| Cargo.toml | ||
| README.md | ||
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
PrivRequestvariant 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.