Run the router as its own account, ask unlinking of the linked account, and take no approval where an agent can become root (hq ADR 0259 §7, §8)

modules/sudo/cmd/sudo-tools/escalation.go

@@ -0,0 +1,89 @@
+package main
+
+// Who can become root here without a person (novox/hq ADR 0259 §8): the controller's self-check asks it of
+// every machine where the router or a channel proving its sender runs, for the accounts agents run as and
+// the account the machine's runtime runs commands as.
+//
+// Root without a person is any of: a sudo rule letting the account run every command as root with no
+// password; membership of a group that is root by another name (docker, which mounts the host; disk, which
+// reads it raw; wheel or sudo only where a rule grants them without a password, which the listing shows); or
+// the account being root itself.
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// Escalation is one account's answer.
+type Escalation struct {
+	Account string `json:"account"`
+	Root    bool   `json:"root_without_a_person"`
+	Why     string `json:"why"`
+}
+
+// rootGroups are groups that are root by another name.
+var rootGroups = map[string]string{"docker": "the docker group, which can mount the machine's root file system",
+	"disk": "the disk group, which reads and writes the drives raw", "root": "the root group"}
+
+var accountShape = regexp.MustCompile(`^[a-z_][a-z0-9_-]{0,31}$`)
+
+// Escalations answers, for each account, whether it can become root here without a person.
+func (m *Machine) Escalations(accounts []string) ([]Escalation, error) {
+	if len(accounts) == 0 {
+		return nil, fmt.Errorf("name the accounts to judge")
+	}
+	var out []Escalation
+	for _, a := range accounts {
+		if !accountShape.MatchString(a) {
+			return nil, fmt.Errorf("%q is not an account name", a)
+		}
+		out = append(out, m.escalation(a))
+	}
+	return out, nil
+}
+
+func (m *Machine) escalation(account string) Escalation {
+	e := Escalation{Account: account}
+	if account == "root" {
+		e.Root, e.Why = true, "it is root"
+		return e
+	}
+	id := m.Run(bg(), "id", "-nG", account)
+	if id.Status != 0 || id.Err != "" {
+		e.Why = "no such account here"
+		return e
+	}
+	for _, g := range strings.Fields(id.Stdout) {
+		if why, ok := rootGroups[g]; ok {
+			e.Root, e.Why = true, "a member of "+why
+			return e
+		}
+	}
+	// sudo's own word, for that account: listing another account's rules needs root, which the runtime's
+	// account escalates to as the mesh's acting tools do.
+	r := m.Run(bg(), "sudo", "-n", "-l", "-U", account)
+	if r.Status != 0 || r.Err != "" {
+		if strings.Contains(r.Stdout+r.Stderr, "not allowed to run sudo") {
+			e.Why = "no sudo rule names it"
+			return e
+		}
+		e.Why = "sudo could not be asked: " + strings.TrimSpace(firstLine(r.Stderr+r.Err))
+		return e
+	}
+	if strings.Contains(r.Stdout, "is not allowed to run sudo") {
+		e.Why = "no sudo rule names it"
+		return e
+	}
+	rules := ParseList(r.Stdout, account)
+	if rules.PasswordlessAll {
+		for _, rule := range rules.Rules {
+			if hasTag(rule.Tags, "NOPASSWD") && contains(rule.Commands, "ALL") && runsAsRoot(rule.RunAs) {
+				e.Root, e.Why = true, "sudo lets it run every command as root without a password ("+rule.Line+")"
+				return e
+			}
+		}
+	}
+	e.Why = "sudo asks it for a password, or lets it run named commands only"
+	return e
+}