From 1109092def2045c4498f28efa04bdea39c5a0ad7 Mon Sep 17 00:00:00 2001 From: kisfenyo Date: Fri, 23 Oct 2026 08:22:17 +0200 Subject: [PATCH] =?UTF-8?q?D4=20(R-982):=20root=20SSH=20from=20the=20LAN?= =?UTF-8?q?=20by=20key=20only=20=E2=80=94=20the=20bundle's=20sshd=20drop-i?= =?UTF-8?q?n,=20try-reload-or-restart,=20an=20sshd=20-T=20read-back=20repo?= =?UTF-8?q?rted=20when=20not=20in=20force,=20a=20reload=20in=20undo=20(the?= =?UTF-8?q?=20reviewed=20v2=20patch);=20unreleased?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- CHANGELOG.md | 8 +++ configs/felhom-os-apply | 44 +++++++++++++- configs/felhom-root-ssh-key-only.conf | 7 +++ configs/test_felhom_config_bundle.py | 84 +++++++++++++++++++++++++++ 4 files changed, 140 insertions(+), 3 deletions(-) create mode 100644 configs/felhom-root-ssh-key-only.conf diff --git a/CHANGELOG.md b/CHANGELOG.md index 2b29f14..edffe89 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -21,6 +21,14 @@ `TestD30_TheHourBoundSurvivesARestart`, red-proved. **Live (felhom.eu `audits/night-2026-10-23/P2-D30/`):** the D30 re-key ran on a test box (before these two changes): clock corrected → 15 min → new key registered → the box switched at its next desired-state fetch → a handshake with the new key. +- **D4 (operator ruling 2026-10-22, R-982) — root SSH from the LAN by key only, on `main` now (2026-10-23 day brief).** The + config bundle carries `/etc/ssh/sshd_config.d/10-felhom-root-key-only.conf` (`PermitRootLogin prohibit-password`; + content check: exactly that line, `sshd -t -f`). After an install that wrote it: `sshd -t` (the whole config), then + `systemctl try-reload-or-restart ssh` (a stopped or socket-activated sshd no longer refuses the bundle), then `sshd -T` + is read back and a drop-in that is NOT in force (no Include, an earlier drop-in, a Match block) is said loudly and + reported as `sshd_dropin_not_in_force` — never a refusal; an undone bundle reloads sshd again. The console and the + web page keep the root password; felhom-sshd (8822) is not touched. Tests `RootKeyOnly` (6), red-proved; the + installer's uninstall removes the file (felhom.eu installer 1.36.0). Reviewed 2026-10-23 night (A1–A7). - **Known gap, unchanged (filed):** after a reboot the kernel forgets the future stamp (latest handshake 0), so neither this re-key nor the hub's alarm sees a box whose clock was corrected and which then restarted (R-1223). diff --git a/configs/felhom-os-apply b/configs/felhom-os-apply index 81565fb..ee8429f 100755 --- a/configs/felhom-os-apply +++ b/configs/felhom-os-apply @@ -165,7 +165,8 @@ KERNEL_ACTIVE = ("staged", "oneshot", "judging", "reverting") # dest: (source file under configs/, mode, check, policy) # check: the content check BEFORE anything is written (R18): sudoers → visudo -cf; sh / bash → -n; python → compile; # unit → a [Unit]/[Service]/[Timer] section; unit-nort → that, and never RuntimeDirectory= (the G1 incident); -# agent-unit → User=felhom-agent; dropin → a [Unit] section (SF-3); nft → nft -c -f; plain → none. +# agent-unit → User=felhom-agent; dropin → a [Unit] section (SF-3); nft → nft -c -f; plain → none; +# sshd → `sshd -t -f` on the snippet alone (R-982). # policy: replace → always written when it differs; if-absent → only when the box has none (a setting the operator may # have tuned); oob → only on a box with the OOB belt (/etc/felhom-sshd exists — the installer's --no-oob leaves none). # Order matters: the sudoers files come LAST, so a referenced wrapper is in place before the line that allows it. @@ -184,6 +185,9 @@ BUNDLE_KEEP = 3 BUNDLE_MAX_BYTES = 4 * 1024 * 1024 BUNDLE_RE = re.compile(r"^bundle-[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z.]+)?\.json$") OOB_DIR = "/etc/felhom-sshd" +# R-982: the host's own sshd drop-in (after_install reloads sshd for it; undo reloads after putting it back). +SSHD_DROPIN = "/etc/ssh/sshd_config.d/10-felhom-root-key-only.conf" + BUNDLE_FILES = [ ("/usr/local/sbin/felhom-mkfs-guarded", "felhom-mkfs-guarded.sh", 0o755, "bash", "replace"), ("/usr/local/sbin/felhom-selfupdate-guarded", "felhom-selfupdate-guarded", 0o755, "sh", "replace"), @@ -221,6 +225,9 @@ BUNDLE_FILES = [ ("/etc/systemd/system/felhom-sshd.service", "felhom-sshd.service", 0o644, "unit-nort", "oob"), ("/etc/felhom-oob.nft", "felhom-oob.nft", 0o644, "nft", "oob"), ("/etc/systemd/system/felhom-oob-nft.service", "felhom-oob-nft.service", 0o644, "unit", "oob"), + # R-982, operator ruling D4 (2026-10-22): the host's own sshd (port 22, the LAN): root by key only. The console + # password stays; felhom-sshd (the operator's door) reads nothing from sshd_config.d. Reloaded in after_install. + ("/etc/ssh/sshd_config.d/10-felhom-root-key-only.conf", "felhom-root-ssh-key-only.conf", 0o644, "sshd", "replace"), ("/etc/sudoers.d/felhom-op", "felhom-op.sudoers", 0o440, "sudoers", "oob"), ("/etc/sudoers.d/felhom-agent", "felhom-agent.sudoers", 0o440, "sudoers", "replace"), ] @@ -434,7 +441,8 @@ class Runner: def check_content(self, kind, data): """Run an external syntax check on a root-only temp copy. Returns (rc, message).""" import tempfile - cmd = {"sudoers": ["visudo", "-cf"], "sh": ["sh", "-n"], "bash": ["bash", "-n"], "nft": ["nft", "-c", "-f"]}[kind] + cmd = {"sudoers": ["visudo", "-cf"], "sh": ["sh", "-n"], "bash": ["bash", "-n"], "nft": ["nft", "-c", "-f"], + "sshd": ["/usr/sbin/sshd", "-t", "-f"]}[kind] with tempfile.TemporaryDirectory(prefix="felhom-bundle-") as d: p = os.path.join(d, "f") with open(p, "wb") as f: @@ -1864,6 +1872,7 @@ class Bundle: def __init__(self, apply): self.a, self.r = apply, apply.r self.report = apply.report + self.sshd_dropin_not_in_force = False # ---------- reading and checking ---------- def load_file(self, path): @@ -1932,10 +1941,17 @@ class Bundle: text = content.decode("utf-8") except UnicodeDecodeError: raise Refused("R18", f"{dest} is not UTF-8 text") - if check in ("sudoers", "sh", "bash", "nft"): + if check in ("sudoers", "sh", "bash", "nft", "sshd"): rc, msg = self.r.check_content(check, content) if rc != 0: raise Refused("R18", f"{dest} fails its {check} check: {msg}") + if check == "sshd": + # R-982: the drop-in's PermitRootLogin must be exactly `prohibit-password`. `no` would also shut the root key + # out (Proxmox's own node-to-node SSH and the LAN key route), `yes` would undo the ruling — both refused. + # Only that line is pinned: the file is signed like every bundle file (review A7). + vals = re.findall(r"^\s*PermitRootLogin\s+(\S+)\s*$", text, re.M | re.I) + if vals != ["prohibit-password"]: + raise Refused("R18", f"{dest} must set exactly `PermitRootLogin prohibit-password` (found {vals})") elif check == "python": try: compile(text, dest, "exec") @@ -2044,6 +2060,8 @@ class Bundle: self.report["failed"] = {"rc": 3, "step": "bundle", "reason": reason[:300]} return 3 rep["signers_created"] = False + if self.sshd_dropin_not_in_force: + rep["sshd_dropin_not_in_force"] = True # R-982 A2: written and reloaded, but sshd -T shows root passwords allowed if bootstrap and not self.r.lexists(TRUST_SIGNERS): self.r.put_file(TRUST_SIGNERS, pinned_signers_line().encode(), 0o644) rep["signers_created"] = True @@ -2073,6 +2091,23 @@ class Bundle: "enable the crash guard") if "/etc/systemd/system/felhom-mgmt-watchdog.timer" in dests: self.must(["systemctl", "enable", "--now", "felhom-mgmt-watchdog.timer"], "enable the mgmt watchdog timer") + # R-982: the host's sshd takes the root-key-only drop-in. The WHOLE config is tested first (a failure is a + # refusal, and the bundle undo puts the old files back); `try-reload-or-restart` keeps every open session and + # does nothing on a box whose ssh.service is not running (a socket-activated or stopped sshd reads the file + # at its next start) — a failure there must not freeze the bundle route (review 2026-10-22 night, A1). + # felhom-sshd is not touched. Then the POSITIVE check: sshd's own effective view for root. A box whose + # sshd_config has no Include of sshd_config.d, an earlier drop-in or a Match block can keep the password route + # — that is said loudly in the log and the report, never silently recorded as done (A2). + if SSHD_DROPIN in written: + self.must(["/usr/sbin/sshd", "-t"], "sshd -t (the host's whole sshd config)") + self.must(["systemctl", "try-reload-or-restart", "ssh"], "systemctl try-reload-or-restart ssh") + rc, out, err = self.r.host(["/usr/sbin/sshd", "-T", "-C", "user=root,host=felhom-check,addr=192.0.2.1"], 60) + eff = re.findall(r"^permitrootlogin\s+(\S+)", out, re.M | re.I) + if rc != 0 or eff != ["without-password"]: + self.r.log(f"os-apply: BUNDLE WARNING the root-key-only drop-in is NOT in force: sshd -T says " + f"permitrootlogin={eff or '?'} (rc={rc}) — check sshd_config's Include, an earlier drop-in " + f"or a Match block (R-982)") + self.sshd_dropin_not_in_force = True def must(self, argv, what): rc, out, err = self.r.host(argv, 120) @@ -2133,6 +2168,9 @@ class Bundle: self.r.log(f"os-apply: BUNDLE UNDO could not restore {dest}: {e}") if any(d.startswith("/etc/systemd/system/") for d in back): self.r.host(["systemctl", "daemon-reload"], 120) + if SSHD_DROPIN in back: + # A3: after_install may already have reloaded sshd with the drop-in; the restored state takes effect now. + self.r.host(["systemctl", "try-reload-or-restart", "ssh"], 120) rc, _, _ = self.r.host(["visudo", "-c"], 60) self.r.log(f"os-apply: BUNDLE UNDO restored={len(back)} visudo-after={'ok' if rc == 0 else 'FAILED'}") return back diff --git a/configs/felhom-root-ssh-key-only.conf b/configs/felhom-root-ssh-key-only.conf new file mode 100644 index 0000000..d92eea9 --- /dev/null +++ b/configs/felhom-root-ssh-key-only.conf @@ -0,0 +1,7 @@ +# MANAGED BY FELHOM (the agent's config bundle) — R-982, operator ruling D4 (2026-10-22). +# The Proxmox host's OWN sshd — the listener the household network reaches on port 22: root logs in with a KEY only. +# The root password still works on the console (the break-glass password: felhom.eu runbooks/break-glass.md). The +# operator's door (felhom-sshd, port 8822, /etc/felhom-sshd/sshd_config) is a separate daemon whose config includes +# nothing from here, so it is not changed. Debian's sshd_config reads this folder BEFORE its own settings, and for +# sshd the first value wins; the bundle checks the effective value with `sshd -T` after the reload. +PermitRootLogin prohibit-password diff --git a/configs/test_felhom_config_bundle.py b/configs/test_felhom_config_bundle.py index 1c5a6ab..58b5238 100644 --- a/configs/test_felhom_config_bundle.py +++ b/configs/test_felhom_config_bundle.py @@ -429,6 +429,90 @@ class SelfCheckUndo(unittest.TestCase): self.assert_restored(box, before, rep) + +class RootKeyOnly(unittest.TestCase): + """R-982, operator ruling D4 (2026-10-22): the bundle gives the host's own sshd a root-key-only drop-in, tests the + whole config and reloads sshd — only when the file was written; a drop-in that says anything but + `prohibit-password` is refused before anything is written. + RED-PROOF: with the after_install block removed, test_fresh_box_takes_the_dropin_and_reloads fails (no reload); + with the content rule removed, test_a_dropin_that_says_yes_or_no_is_refused fails — seen failing 2026-10-22.""" + DEST = "/etc/ssh/sshd_config.d/10-felhom-root-key-only.conf" + + def test_fresh_box_takes_the_dropin_and_reloads(self): + data, sha = real_bundle() + box = Box(data, signed_job(sha)) + rc, rep = run(box) + self.assertEqual(rc, 0, rep) + self.assertIn(b"PermitRootLogin prohibit-password", box.files[self.DEST]) + self.assertEqual(box.modes[self.DEST], 0o644) + self.assertIn(["/usr/sbin/sshd", "-t"], box.calls) + self.assertIn(["systemctl", "try-reload-or-restart", "ssh"], box.calls) + self.assertLess(box.calls.index(["/usr/sbin/sshd", "-t"]), box.calls.index(["systemctl", "try-reload-or-restart", "ssh"])) + self.assertFalse(any("felhom-sshd" in " ".join(c) for c in box.calls), "the operator's door must not be touched") + + def test_an_unchanged_dropin_is_not_reloaded(self): + data, sha = real_bundle() + box = Box(data, signed_job(sha)) + box.put(self.DEST, (REPO / "configs" / "felhom-root-ssh-key-only.conf").read_bytes(), 0o644) + rc, rep = run(box) + self.assertEqual(rc, 0, rep) + self.assertNotIn(["systemctl", "try-reload-or-restart", "ssh"], box.calls) + + def test_a_dropin_that_says_yes_or_no_is_refused(self): + for bad in (b"PermitRootLogin yes\n", b"PermitRootLogin no\n", b"# nothing\n", + b"PermitRootLogin prohibit-password\nPermitRootLogin yes\n"): + def edit(files, bad=bad): + for e in files: + if e["path"] == self.DEST: + e["content_b64"] = base64.b64encode(bad).decode() + data, sha = edited_bundle(edit) + box = Box(data, signed_job(sha)) + rc, rep = run(box) + self.assertNotEqual(rc, 0, bad) + self.assertNotIn(self.DEST, box.files, bad) + + # Review 2026-10-22 night. A2: the effective value is read back with `sshd -T`; a drop-in that is not in force is + # said in the log and the report (not refused — a refusal would freeze the bundle route). A3: a bundle undone + # after the reload reloads sshd again with the old state. RED-PROOF: with the sshd -T check removed, + # test_a_dropin_not_in_force_is_reported fails; with the undo reload removed, test_an_undone_bundle_reloads_sshd + # fails — seen failing 2026-10-22 night. + def _sshd_T(self, box, value): + orig = box.host + def host(argv, timeout=600, stdin=None): + if argv[:2] == ["/usr/sbin/sshd", "-T"]: + box.calls.append(argv) + return 0, f"port 22\npermitrootlogin {value}\npasswordauthentication yes\n", "" + return orig(argv, timeout, stdin) + box.host = host + + def test_the_effective_value_is_checked(self): + data, sha = real_bundle() + box = Box(data, signed_job(sha)) + self._sshd_T(box, "without-password") + rc, rep = run(box) + self.assertEqual(rc, 0, rep) + self.assertTrue(any(c[:2] == ["/usr/sbin/sshd", "-T"] for c in box.calls)) + self.assertNotIn("sshd_dropin_not_in_force", rep["bundle"]) + + def test_a_dropin_not_in_force_is_reported(self): + data, sha = real_bundle() + box = Box(data, signed_job(sha)) + self._sshd_T(box, "yes") # e.g. no Include of sshd_config.d + rc, rep = run(box) + self.assertEqual(rc, 0, rep) + self.assertTrue(rep["bundle"].get("sshd_dropin_not_in_force"), rep) + self.assertTrue(any("NOT in force" in l for l in box.logs), box.logs) + + def test_an_undone_bundle_reloads_sshd(self): + data, sha = real_bundle() + box = Box(data, signed_job(sha)) + box.visudo_fail = True # the self-check fails AFTER the install → undo + rc, rep = run(box) + self.assertEqual(rc, 3, rep) + self.assertNotIn(self.DEST, box.files) + reloads = [i for i, c in enumerate(box.calls) if c == ["systemctl", "try-reload-or-restart", "ssh"]] + self.assertEqual(len(reloads), 2, box.calls) # after_install, then the undo + class TrustBootstrap(unittest.TestCase): def test_missing_signers_verifies_against_the_pinned_key_and_creates_it(self): data, sha = real_bundle()