Certificates for other hosts: jarl cert get

jarld obtains and renews a certificate for another host; the host asks
for it with one command, waits, downloads it when it is newer than its
copy and runs a hook with the paths in JARL_CERT_* variables.

- Certificates have an owner user; another user can't take the name.
  An existing one is obtained again only when a name is added or
  removed. A new certificates grant (names=) says which names a user
  may have; it is never part of "*". Users may own
  certificates.max_per_user certificates (10) or their own cert_limit.
- POST /certificates/{name}/request; owners may list, show, export and
  delete theirs; keys only over HTTPS, the socket or loopback; every
  download is recorded and shown as "Pulled by".
- CLI: jarl cert get (saved settings, all saved when no name), cert
  saved, cert forget, cert schedule (daily systemd timer, Linux, root).
- Migration 14. Tests: server, auth, and e2e against Pebble.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/auth/auth_test.go

@@ -134,3 +134,23 @@ func TestRoleTemplatesValid(t *testing.T) {
 		}
 	}
 }
+
+func TestCertificateGrants(t *testing.T) {
+	g, err := ParseGrant("certificates:write names=*.adbraun.lol")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !GrantAllows(g, Action{Resource: ResCerts, Write: true, Name: "mail.adbraun.lol"}) || GrantAllows(g, Action{Resource: ResCerts, Write: true, Name: "mail.example.org"}) {
+		t.Error("names filter")
+	}
+	if _, err := ParseGrant("certificates:read types=TXT"); err == nil {
+		t.Error("types on certificates accepted")
+	}
+	if _, err := ParseGrant("certificates:read zones=adbraun.lol"); err == nil {
+		t.Error("zones on certificates accepted")
+	}
+	// "*" never covers certificates: they hand out private keys.
+	if GrantAllows(model.Grant{Resource: ResAll, Access: Write}, Action{Resource: ResCerts, Name: "mail.adbraun.lol"}) {
+		t.Error("* covers certificates")
+	}
+}

internal/auth/grants.go

@@ -21,11 +21,14 @@ const (
 	ResAudit    = "audit"    // audit log and everyone's changesets
 	ResStats    = "stats"    // query statistics
 	ResBlocking = "blocking" // blocklists and block/allow rules
-	ResAll      = "*"
+	// ResCerts is certificates for other hosts (jarl cert get), by the
+	// names in them. It is never part of "*": it hands out private keys.
+	ResCerts = "certificates"
+	ResAll   = "*"
 )
 
 // Resources lists the resources in display order.
-var Resources = []string{ResZones, ResRecords, ResViews, ResACLs, ResTSIG, ResOptions, ResAudit, ResStats, ResBlocking}
+var Resources = []string{ResZones, ResRecords, ResViews, ResACLs, ResTSIG, ResOptions, ResAudit, ResStats, ResBlocking, ResCerts}
 
 // Access levels.
 const (
@@ -74,8 +77,11 @@ func ValidateGrant(g *model.Grant) error {
 	for i, t := range g.Types {
 		g.Types[i] = strings.ToUpper(t)
 	}
-	if (len(g.Names) > 0 || len(g.Types) > 0) && g.Resource != ResRecords {
-		return fmt.Errorf("names and types filters only apply to the records resource")
+	if len(g.Types) > 0 && g.Resource != ResRecords {
+		return fmt.Errorf("the types filter only applies to the records resource")
+	}
+	if len(g.Names) > 0 && g.Resource != ResRecords && g.Resource != ResCerts {
+		return fmt.Errorf("the names filter only applies to the records and certificates resources")
 	}
 	if (len(g.Zones) > 0 || len(g.Views) > 0) && g.Resource != ResRecords && g.Resource != ResZones && g.Resource != ResViews {
 		return fmt.Errorf("zone and view filters only apply to the zones, records and views resources")
@@ -228,6 +234,9 @@ func GrantAllows(g model.Grant, a Action) bool {
 	if g.Resource != ResAll && g.Resource != a.Resource {
 		return false
 	}
+	if g.Resource == ResAll && a.Resource == ResCerts {
+		return false // only an explicit certificates grant
+	}
 	if a.Write && g.Access != Write {
 		return false
 	}