forked from heavy-duty/rig
fff45a9835
The headline of #17: rig can verify a lot locally, but never that the operator HOLDS the admin's private key. Seeding authorized_keys from root's current /root/.ssh/authorized_keys turns that unprovable claim into a proven one — the operator is connected as root right now using one of those keys. The users file gains the literal key-field token '@root', shape-validated in the parse pass (exit 2, pre-root-check, testable non-root); apply resolves it once after the root check, dies with the repair when root has no keys to seed, copies key lines verbatim (options included — rig will not silently widen what a key can do), and writes seeded keys first with literal lines appended, so the cmp-guard keeps re-runs convergent to root's then-current keys plus the literals. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
339 lines
15 KiB
Bash
Executable file
339 lines
15 KiB
Bash
Executable file
#!/usr/bin/env bash
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# rig users apply — converge named operator accounts from a declarative users
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# file, on every class. Humans always enter as themselves and elevate via
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# sudo: a shared root login is unattributable, so operators belong on servers
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# too — class never gates this command, it only decides root SSH's fate AFTER
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# users exist (close-root on human, kept as the control plane's automation
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# door on server). Convergent: a second identical run changes nothing and
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# says so.
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set -euo pipefail
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HERE="$(cd "$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")" && pwd)"
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# shellcheck source=SCRIPTDIR/lib/users-config.sh
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. "$HERE/lib/users-config.sh"
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log() { printf 'rig-users: %s\n' "$*"; }
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warn() { printf 'rig-users: WARNING: %s\n' "$*" >&2; }
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die() { printf 'rig-users: ERROR: %s\n' "$1" >&2; exit "${2:-1}"; }
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usage() {
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cat <<'EOF'
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usage: rig users apply --file <path>
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--file <path> users file (required; '-' reads it from stdin)
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The file is line-based and bash-parseable on purpose — a rig box has no YAML
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parser and no jq, and gets neither for this. Whitespace-separated: user,
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comma-joined roles, then the SSH public key (the rest of the line). '#'
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comments and blank lines are fine. Repeated username lines add authorized
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keys; the roles must be identical on every line of one user.
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# user roles ssh public key
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dan admin,box ssh-ed25519 AAAA... dan@laptop
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maria rig,box ssh-ed25519 AAAA... maria@mac
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The key field may also be the literal token '@root': this user's
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authorized_keys is seeded from root's CURRENT /root/.ssh/authorized_keys.
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You provably hold a root private key — you SSHed in with it to run apply at
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all — so the seeded key is the one key that cannot lock you out. '@root'
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mixes with literal key lines: seeded keys land first, literal keys are
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appended after them, and every re-run re-seeds from root's then-current file
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(convergent to it — a seeded key you remove from the admin by hand returns;
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switch the line to literal keys to pin them). Root's key lines are copied
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verbatim, options included — a from= or command= restriction on a root key
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follows it to the user. Apply dies if root has no authorized_keys to seed.
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roles:
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admin group rig-admin — full NOPASSWD sudo
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rig group rig — NOPASSWD sudo for /usr/local/bin/rig only
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box group incus — Incus restricted tier, no sudo (box's setup-host
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owns the Incus install; rig only asserts it)
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All passwords stay locked, always — the SSH key at the door is the
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authentication, and NOPASSWD sudo does not weaken it. Convergent: membership
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in the three rig-managed groups is made exact (other groups are never
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touched), authorized_keys becomes exactly the file's keys, and a user dropped
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from the file is REVOKED: account expired (which blocks SSH keys too, not
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just the password), authorized_keys renamed to authorized_keys.revoked-by-rig,
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rig groups stripped — home kept, nothing deleted, and re-adding the user
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brings them back. Run as root; under sudo, only rig-admin members may — the
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users family changes who holds root, so role rig's scoped sudo does not reach
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it.
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EOF
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}
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# --- args (validated before the root check, so errors are testable) ---------
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FILE=""
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while [ $# -gt 0 ]; do
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case "$1" in
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--file)
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[ $# -ge 2 ] || die "--file needs a value" 2
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FILE="$2"; shift 2 ;;
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-h|--help) usage; exit 0 ;;
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*) die "unknown flag: $1" 2 ;;
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esac
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done
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[ -n "$FILE" ] || die "--file <path> is required" 2
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# stdin is read ONCE into a temp: the file is parsed for validation and then
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# walked again to converge, and a pipe only plays once.
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if [ "$FILE" = "-" ]; then
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STDIN_TMP="$(mktemp)"
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cat > "$STDIN_TMP"
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FILE="$STDIN_TMP"
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fi
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[ -r "$FILE" ] || die "cannot read users file: $FILE" 2
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# File parsing is argument validation: every error in the file is reported in
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# one pass, exit 2, still before the root check.
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PARSED="$(parse_users_file "$FILE")" \
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|| die "invalid users file: $FILE — every error is listed above; nothing was changed" 2
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declare -A USER_ROLES=() USER_KEYS=() USER_SEED=()
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USERS=()
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BOX_USERS=()
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NEED_SUDO=0
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NEED_INCUS=0
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NEED_SEED=0
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while IFS='|' read -r u r k; do
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[ -n "$u" ] || continue
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if [ -z "${USER_ROLES[$u]:-}" ]; then
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USERS+=("$u")
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USER_ROLES[$u]="$r"
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case ",$r," in *,box,*) BOX_USERS+=("$u") ;; esac
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fi
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# '@root' is a key SOURCE, not a key: remember who seeds and resolve the
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# actual lines after the root check — /root/.ssh is unreadable before it.
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if [ "$k" = "@root" ]; then
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USER_SEED[$u]=1
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NEED_SEED=1
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else
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USER_KEYS[$u]="${USER_KEYS[$u]:-}$k"$'\n'
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fi
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case ",$r," in *,admin,*|*,rig,*) NEED_SUDO=1 ;; esac
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case ",$r," in *,box,*) NEED_INCUS=1 ;; esac
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done <<< "$PARSED"
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# --- guards ------------------------------------------------------------------
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[ "$(id -u)" -eq 0 ] || die "must run as root"
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# Identity management gates its INVOKER, not just its uid: %rig's sudoers rule
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# is binary-scoped but not argument-scoped, so without this gate a rig-role
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# user could run `sudo rig users apply --file <me-as-admin>` — the scoped
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# grant silently root-equivalent through this very command. Direct root (no
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# SUDO_USER: bring-up, a root shell) proceeds.
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if [ -n "${SUDO_USER:-}" ] && [ "$SUDO_USER" != "root" ] \
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&& ! id -nG "$SUDO_USER" 2>/dev/null | tr ' ' '\n' | grep -qx rig-admin; then
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die "the users family changes who holds root — only rig-admin members (or root itself) may run it; role rig grants operational rig use, not identity management (invoker: $SUDO_USER)"
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fi
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# --- @root seed source (#17) -------------------------------------------------
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# The lockout-avoidance move: the operator SSHed in as root to run this at
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# all, so root's CURRENT authorized_keys provably contains a key they hold —
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# the one claim no local check can make about a pasted literal. Resolved ONCE
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# here (post-root-check: /root/.ssh needs root) and copied verbatim, options
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# included: a from=/command= restriction on a root key line follows it to the
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# user, which is honest — rig will not silently widen what a key can do.
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# Comments and blanks are dropped so the seeded block is exactly key lines;
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# an empty result is a hard stop, because seeding nothing would converge the
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# admin's authorized_keys to empty and close-root would then refuse — better
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# to name the real problem now.
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ROOT_SEED_KEYS=""
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if [ "$NEED_SEED" -eq 1 ]; then
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ROOT_SEED_KEYS="$(grep -Ev '^[[:space:]]*(#|$)' /root/.ssh/authorized_keys 2>/dev/null || true)"
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[ -n "$ROOT_SEED_KEYS" ] \
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|| die "a user's keys seed from @root but root has no authorized_keys (/root/.ssh/authorized_keys missing or without key lines) — @root's whole point is copying a key you provably hold; list a literal key instead"
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fi
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# Class is a note, never a refusal: #26's call is that operators belong on
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# EVERY class — what differs is root SSH's fate once they exist.
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case "$(read_role_marker "${RIG_ROLE_MARKER:-/etc/rig/role}")" in
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*class=server*) log "class=server: root SSH stays — it is the control plane's automation door" ;;
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*class=human*) log "class=human: once your admin key works, 'rig users close-root' shuts the root door" ;;
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"") warn "no /etc/rig/role marker — re-run rig bootstrap so this box knows what it is" ;;
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esac
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CHANGED=0
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# --- sudo (only when some role actually grants through it) -------------------
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if [ "$NEED_SUDO" -eq 1 ] && ! command -v sudo >/dev/null 2>&1; then
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log "installing sudo (admin/rig grants go through it)"
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DEBIAN_FRONTEND=noninteractive apt-get install -y -qq sudo
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CHANGED=1
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fi
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# --- groups ------------------------------------------------------------------
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groupadd -f rig-admin
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groupadd -f rig
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# rig NEVER installs Incus: box's setup-host owns the daemon and its group. An
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# absent incus group means that never ran — but what that MEANS is the host=
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# trait's call. The box role binds where VMs live; a users file is fleet-wide,
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# its box grants are not. So on host=yes an absent group is a broken VM host
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# (refuse, point at setup-host), while on host=no it is simply not this box's
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# role to converge — skip it, never abort the admins the file also carries.
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INCUS_OK=0
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if getent group incus >/dev/null; then INCUS_OK=1; fi
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if [ "$NEED_INCUS" -eq 1 ] && [ "$INCUS_OK" -eq 0 ]; then
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case "$(read_role_marker "${RIG_ROLE_MARKER:-/etc/rig/role}")" in
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*host=yes*)
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die "a user carries role box and this box hosts VMs (host=yes) but group incus is absent — install the box CLI and run 'box setup-host' first; rig never installs Incus" ;;
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*host=no*)
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warn "box role skipped for ${BOX_USERS[*]}: this box does not host VMs (host=no); everything else converges" ;;
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*)
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warn "box role skipped for ${BOX_USERS[*]}: the role marker names no host= trait — re-run rig bootstrap so this box knows whether it hosts VMs" ;;
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esac
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fi
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in_group() { id -nG "$1" 2>/dev/null | tr ' ' '\n' | grep -qx "$2"; }
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# --- converge each user ------------------------------------------------------
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for u in "${USERS[@]}"; do
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if ! id -u "$u" >/dev/null 2>&1; then
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useradd -m -s /bin/bash "$u"
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log "created user $u"
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CHANGED=1
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fi
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# Locked always, created or found: no password ever exists to guess or
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# rotate — the SSH key at the door is the authentication. The expiry is
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# cleared just as idempotently: revocation below IS an expiry date, so a
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# user dropped once and re-added comes back to life on this line.
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usermod -L -e '' "$u"
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# Membership in the three rig-managed groups is made EXACT — added and
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# removed to match the file. Other groups are never touched: they are not
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# rig's to converge.
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roles="${USER_ROLES[$u]}"
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want=""
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case ",$roles," in *,admin,*) want="$want rig-admin" ;; esac
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case ",$roles," in *,rig,*) want="$want rig" ;; esac
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# incus joins the wanted set only when the group exists (host=no boxes
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# skipped it above): converging membership in a conjured group would hand
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# the daemon's arrival an audience it never granted.
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case ",$roles," in *,box,*) if [ "$INCUS_OK" -eq 1 ]; then want="$want incus"; fi ;; esac
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for g in rig-admin rig incus; do
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case " $want " in
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*" $g "*)
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if ! in_group "$u" "$g"; then
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usermod -aG "$g" "$u"
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log "added $u to $g"
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CHANGED=1
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fi ;;
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*)
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if in_group "$u" "$g"; then
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gpasswd -d "$u" "$g" >/dev/null
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log "removed $u from $g"
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CHANGED=1
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fi ;;
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esac
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done
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# authorized_keys becomes exactly the file's keys — only the content WRITE
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# is cmp-guarded, so an unchanged file is a clean no-op. Ownership and mode
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# converge UNCONDITIONALLY: sshd's StrictModes treats them as load-bearing
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# (a group-writable .ssh is a rejected key), so drifted perms behind
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# matching content would otherwise stay broken while apply logs "already
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# converged". Perms are part of the converged state.
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home="$(getent passwd "$u" | cut -d: -f6)"
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ugroup="$(id -gn "$u")"
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mkdir -p "$home/.ssh"
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# Seeded (@root) keys land FIRST, literal lines append after — fixed order
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# so the cmp-guard sees identical bytes on identical state and re-runs
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# converge to root's then-current keys plus the literals (#17). A literal
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# that duplicates a seeded key writes twice; sshd does not mind and the
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# bytes stay deterministic.
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AK_TMP="$(mktemp)"
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{
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if [ -n "${USER_SEED[$u]:-}" ]; then printf '%s\n' "$ROOT_SEED_KEYS"; fi
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printf '%s' "${USER_KEYS[$u]:-}"
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} > "$AK_TMP"
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if ! cmp -s "$AK_TMP" "$home/.ssh/authorized_keys" 2>/dev/null; then
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install -m 0600 -o "$u" -g "$ugroup" "$AK_TMP" "$home/.ssh/authorized_keys"
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log "authorized_keys for $u: $(grep -c . "$AK_TMP") key(s)"
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CHANGED=1
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fi
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rm -f "$AK_TMP"
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chmod 0700 "$home/.ssh"
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chown "$u:$ugroup" "$home/.ssh"
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chmod 0600 "$home/.ssh/authorized_keys"
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chown "$u:$ugroup" "$home/.ssh/authorized_keys"
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done
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# --- previously managed users no longer in the file --------------------------
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# The ledger is what lets a REMOVED user be found at all — so it must REMEMBER
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# them: two-field lines, 'name active' / 'name revoked' (a legacy bare name
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# reads as active). Revoked, not deleted: deleting frees the uid for reuse and
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# orphans file ownership — attribution would rot. Home stays for the same
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# reason. But revoked must actually mean revoked: a '!'-locked password is not
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# a closed door under UsePAM — Debian sshd still honors the pubkey — so the
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# lock alone left a dropped operator with working SSH. Account expiry (a date
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# in the past) is the switch PAM actually enforces, against every auth method
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# including keys; the keys themselves are renamed, never deleted — access
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# revoked, data kept, convergence never destroys.
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LEDGER=/etc/rig/users
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REVOKED=()
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if [ -r "$LEDGER" ]; then
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while read -r prev pstate _; do
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[ -n "$prev" ] || continue
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case " ${USERS[*]:-} " in *" $prev "*) continue ;; esac
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id -u "$prev" >/dev/null 2>&1 || continue
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usermod -L -e 1 "$prev"
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prevhome="$(getent passwd "$prev" | cut -d: -f6)"
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if [ -f "$prevhome/.ssh/authorized_keys" ]; then
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mv "$prevhome/.ssh/authorized_keys" "$prevhome/.ssh/authorized_keys.revoked-by-rig"
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fi
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for g in rig-admin rig incus; do
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if in_group "$prev" "$g"; then gpasswd -d "$prev" "$g" >/dev/null; fi
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done
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REVOKED+=("$prev")
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# Warn on the TRANSITION only: an already-revoked user is converged above
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# (quietly — repairing drift, not announcing news) so a second identical
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# run stays a clean no-op.
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if [ "${pstate:-active}" != "revoked" ]; then
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warn "$prev is no longer in the file: account expired (blocks SSH keys too, not just the password), authorized_keys renamed to authorized_keys.revoked-by-rig, rig groups stripped (home kept — rig never deletes a user)"
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CHANGED=1
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fi
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done < "$LEDGER"
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fi
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LEDGER_TMP="$(mktemp)"
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if [ "${#USERS[@]}" -gt 0 ]; then printf '%s active\n' "${USERS[@]}" > "$LEDGER_TMP"; fi
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if [ "${#REVOKED[@]}" -gt 0 ]; then printf '%s revoked\n' "${REVOKED[@]}" >> "$LEDGER_TMP"; fi
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if ! cmp -s "$LEDGER_TMP" "$LEDGER" 2>/dev/null; then
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mkdir -p /etc/rig
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install -m 0644 "$LEDGER_TMP" "$LEDGER"
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CHANGED=1
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fi
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rm -f "$LEDGER_TMP"
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# --- sudoers -----------------------------------------------------------------
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# Both group rules ship in one drop-in whether or not both roles are in use:
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# the groups exist and the rules are inert without members. visudo gates the
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# install because a bad file under /etc/sudoers.d can take down ALL of sudo —
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# locking every admin out of the very escalation path apply just granted.
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SUDOERS_TMP="$(mktemp)"
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cat > "$SUDOERS_TMP" <<'EOF'
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# Managed by `rig users apply` — do not edit; the next apply converges it.
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%rig-admin ALL=(ALL:ALL) NOPASSWD: ALL
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%rig ALL=(root) NOPASSWD: /usr/local/bin/rig
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EOF
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if command -v visudo >/dev/null 2>&1; then
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visudo -c -f "$SUDOERS_TMP" >/dev/null \
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|| die "sudoers candidate failed validation — /etc/sudoers.d untouched; candidate kept at $SUDOERS_TMP for inspection"
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if ! cmp -s "$SUDOERS_TMP" /etc/sudoers.d/rig-roles 2>/dev/null; then
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install -m 0440 "$SUDOERS_TMP" /etc/sudoers.d/rig-roles
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log "sudoers role rules installed (/etc/sudoers.d/rig-roles)"
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CHANGED=1
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fi
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rm -f "$SUDOERS_TMP"
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else
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# No sudo on the box means no role needed it (the install above would have
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# run otherwise): rules for a binary that is not there can wait for the
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# apply that brings a sudo-bearing role.
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rm -f "$SUDOERS_TMP"
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log "sudo not installed and no role needs it; skipping the sudoers drop-in"
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fi
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if [ "$CHANGED" -eq 0 ]; then
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log "already converged; no changes"
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else
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log "converged ${#USERS[@]} user(s)"
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fi
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