package headscale import ( "encoding/json" "fmt" "io" "os" "strconv" "strings" "github.com/rs/zerolog/log" "github.com/tailscale/hujson" "inet.af/netaddr" "tailscale.com/tailcfg" ) const ( errEmptyPolicy = Error("empty policy") errInvalidAction = Error("invalid action") errInvalidUserSection = Error("invalid user section") errInvalidGroup = Error("invalid group") errInvalidTag = Error("invalid tag") errInvalidPortFormat = Error("invalid port format") ) const ( Base8 = 8 Base10 = 10 BitSize16 = 16 BitSize32 = 32 BitSize64 = 64 portRangeBegin = 0 portRangeEnd = 65535 expectedTokenItems = 2 ) // LoadACLPolicy loads the ACL policy from the specify path, and generates the ACL rules. func (h *Headscale) LoadACLPolicy(path string) error { log.Debug(). Str("func", "LoadACLPolicy"). Str("path", path). Msg("Loading ACL policy from path") policyFile, err := os.Open(path) if err != nil { return err } defer policyFile.Close() var policy ACLPolicy policyBytes, err := io.ReadAll(policyFile) if err != nil { return err } ast, err := hujson.Parse(policyBytes) if err != nil { return err } ast.Standardize() policyBytes = ast.Pack() err = json.Unmarshal(policyBytes, &policy) if err != nil { return err } if policy.IsZero() { return errEmptyPolicy } h.aclPolicy = &policy return h.UpdateACLRules() } func (h *Headscale) UpdateACLRules() error { rules, err := h.generateACLRules() if err != nil { return err } log.Trace().Interface("ACL", rules).Msg("ACL rules generated") h.aclRules = rules return nil } func (h *Headscale) generateACLRules() ([]tailcfg.FilterRule, error) { rules := []tailcfg.FilterRule{} if h.aclPolicy == nil { return nil, errEmptyPolicy } machines, err := h.ListAllMachines() if err != nil { return nil, err } for index, acl := range h.aclPolicy.ACLs { if acl.Action != "accept" { return nil, errInvalidAction } srcIPs := []string{} for innerIndex, user := range acl.Users { srcs, err := h.generateACLPolicySrcIP(machines, *h.aclPolicy, user) if err != nil { log.Error(). Msgf("Error parsing ACL %d, User %d", index, innerIndex) return nil, err } srcIPs = append(srcIPs, srcs...) } destPorts := []tailcfg.NetPortRange{} for innerIndex, ports := range acl.Ports { dests, err := h.generateACLPolicyDestPorts(machines, *h.aclPolicy, ports) if err != nil { log.Error(). Msgf("Error parsing ACL %d, Port %d", index, innerIndex) return nil, err } destPorts = append(destPorts, dests...) } rules = append(rules, tailcfg.FilterRule{ SrcIPs: srcIPs, DstPorts: destPorts, }) } return rules, nil } func (h *Headscale) generateACLPolicySrcIP( machines []Machine, aclPolicy ACLPolicy, u string, ) ([]string, error) { return expandAlias(machines, aclPolicy, u) } func (h *Headscale) generateACLPolicyDestPorts( machines []Machine, aclPolicy ACLPolicy, d string, ) ([]tailcfg.NetPortRange, error) { tokens := strings.Split(d, ":") if len(tokens) < expectedTokenItems || len(tokens) > 3 { return nil, errInvalidPortFormat } var alias string // We can have here stuff like: // git-server:* // 192.168.1.0/24:22 // tag:montreal-webserver:80,443 // tag:api-server:443 // example-host-1:* if len(tokens) == expectedTokenItems { alias = tokens[0] } else { alias = fmt.Sprintf("%s:%s", tokens[0], tokens[1]) } expanded, err := expandAlias(machines, aclPolicy, alias) if err != nil { return nil, err } ports, err := expandPorts(tokens[len(tokens)-1]) if err != nil { return nil, err } dests := []tailcfg.NetPortRange{} for _, d := range expanded { for _, p := range *ports { pr := tailcfg.NetPortRange{ IP: d, Ports: p, } dests = append(dests, pr) } } return dests, nil } // expandalias has an input of either // - a namespace // - a group // - a tag // and transform these in IPAddresses. func expandAlias( machines []Machine, aclPolicy ACLPolicy, alias string, ) ([]string, error) { ips := []string{} if alias == "*" { return []string{"*"}, nil } if strings.HasPrefix(alias, "group:") { namespaces, err := expandGroup(aclPolicy, alias) if err != nil { return ips, err } for _, n := range namespaces { nodes := filterMachinesByNamespace(machines, n) for _, node := range nodes { ips = append(ips, node.IPAddresses.ToStringSlice()...) } } return ips, nil } if strings.HasPrefix(alias, "tag:") { owners, err := expandTagOwners(aclPolicy, alias) if err != nil { return ips, err } for _, namespace := range owners { machines := filterMachinesByNamespace(machines, namespace) for _, machine := range machines { if len(machine.HostInfo) == 0 { continue } hi, err := machine.GetHostInfo() if err != nil { return ips, err } for _, t := range hi.RequestTags { if alias == t { ips = append(ips, machine.IPAddresses.ToStringSlice()...) } } } } return ips, nil } // if alias is a namespace nodes := filterMachinesByNamespace(machines, alias) nodes, err := excludeCorrectlyTaggedNodes(aclPolicy, nodes, alias) if err != nil { return ips, err } for _, n := range nodes { ips = append(ips, n.IPAddresses.ToStringSlice()...) } if len(ips) > 0 { return ips, nil } // if alias is an host if h, ok := aclPolicy.Hosts[alias]; ok { return []string{h.String()}, nil } // if alias is an IP ip, err := netaddr.ParseIP(alias) if err == nil { return []string{ip.String()}, nil } // if alias is an CIDR cidr, err := netaddr.ParseIPPrefix(alias) if err == nil { return []string{cidr.String()}, nil } return ips, errInvalidUserSection } // excludeCorrectlyTaggedNodes will remove from the list of input nodes the ones // that are correctly tagged since they should not be listed as being in the namespace // we assume in this function that we only have nodes from 1 namespace. func excludeCorrectlyTaggedNodes( aclPolicy ACLPolicy, nodes []Machine, namespace string, ) ([]Machine, error) { out := []Machine{} tags := []string{} for tag, ns := range aclPolicy.TagOwners { if containsString(ns, namespace) { tags = append(tags, tag) } } // for each machine if tag is in tags list, don't append it. for _, machine := range nodes { if len(machine.HostInfo) == 0 { out = append(out, machine) continue } hi, err := machine.GetHostInfo() if err != nil { return out, err } found := false for _, t := range hi.RequestTags { if containsString(tags, t) { found = true break } } if !found { out = append(out, machine) } } return out, nil } func expandPorts(portsStr string) (*[]tailcfg.PortRange, error) { if portsStr == "*" { return &[]tailcfg.PortRange{ {First: portRangeBegin, Last: portRangeEnd}, }, nil } ports := []tailcfg.PortRange{} for _, portStr := range strings.Split(portsStr, ",") { rang := strings.Split(portStr, "-") switch len(rang) { case 1: port, err := strconv.ParseUint(rang[0], Base10, BitSize16) if err != nil { return nil, err } ports = append(ports, tailcfg.PortRange{ First: uint16(port), Last: uint16(port), }) case expectedTokenItems: start, err := strconv.ParseUint(rang[0], Base10, BitSize16) if err != nil { return nil, err } last, err := strconv.ParseUint(rang[1], Base10, BitSize16) if err != nil { return nil, err } ports = append(ports, tailcfg.PortRange{ First: uint16(start), Last: uint16(last), }) default: return nil, errInvalidPortFormat } } return &ports, nil } func filterMachinesByNamespace(machines []Machine, namespace string) []Machine { out := []Machine{} for _, machine := range machines { if machine.Namespace.Name == namespace { out = append(out, machine) } } return out } // expandTagOwners will return a list of namespace. An owner can be either a namespace or a group // a group cannot be composed of groups. func expandTagOwners(aclPolicy ACLPolicy, tag string) ([]string, error) { var owners []string ows, ok := aclPolicy.TagOwners[tag] if !ok { return []string{}, fmt.Errorf( "%w. %v isn't owned by a TagOwner. Please add one first. https://tailscale.com/kb/1018/acls/#tag-owners", errInvalidTag, tag, ) } for _, owner := range ows { if strings.HasPrefix(owner, "group:") { gs, err := expandGroup(aclPolicy, owner) if err != nil { return []string{}, err } owners = append(owners, gs...) } else { owners = append(owners, owner) } } return owners, nil } // expandGroup will return the list of namespace inside the group // after some validation. func expandGroup(aclPolicy ACLPolicy, group string) ([]string, error) { groups, ok := aclPolicy.Groups[group] if !ok { return []string{}, fmt.Errorf( "group %v isn't registered. %w", group, errInvalidGroup, ) } for _, g := range groups { if strings.HasPrefix(g, "group:") { return []string{}, fmt.Errorf( "%w. A group cannot be composed of groups. https://tailscale.com/kb/1018/acls/#groups", errInvalidGroup, ) } } return groups, nil }