mirror of
https://github.com/juanfont/headscale.git
synced 2024-12-11 18:54:25 +00:00
705 lines
16 KiB
Go
705 lines
16 KiB
Go
package headscale
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import (
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"net/netip"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"time"
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"github.com/rs/zerolog/log"
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"github.com/tailscale/hujson"
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"gopkg.in/yaml.v3"
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"tailscale.com/envknob"
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"tailscale.com/tailcfg"
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)
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const (
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errEmptyPolicy = Error("empty policy")
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errInvalidAction = Error("invalid action")
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errInvalidGroup = Error("invalid group")
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errInvalidTag = Error("invalid tag")
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errInvalidPortFormat = Error("invalid port format")
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errWildcardIsNeeded = Error("wildcard as port is required for the protocol")
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)
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const (
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Base8 = 8
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Base10 = 10
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BitSize16 = 16
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BitSize32 = 32
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BitSize64 = 64
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portRangeBegin = 0
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portRangeEnd = 65535
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expectedTokenItems = 2
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)
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// For some reason golang.org/x/net/internal/iana is an internal package.
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const (
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protocolICMP = 1 // Internet Control Message
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protocolIGMP = 2 // Internet Group Management
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protocolIPv4 = 4 // IPv4 encapsulation
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protocolTCP = 6 // Transmission Control
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protocolEGP = 8 // Exterior Gateway Protocol
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protocolIGP = 9 // any private interior gateway (used by Cisco for their IGRP)
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protocolUDP = 17 // User Datagram
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protocolGRE = 47 // Generic Routing Encapsulation
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protocolESP = 50 // Encap Security Payload
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protocolAH = 51 // Authentication Header
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protocolIPv6ICMP = 58 // ICMP for IPv6
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protocolSCTP = 132 // Stream Control Transmission Protocol
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ProtocolFC = 133 // Fibre Channel
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)
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var featureEnableSSH = envknob.RegisterBool("HEADSCALE_EXPERIMENTAL_FEATURE_SSH")
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// LoadACLPolicy loads the ACL policy from the specify path, and generates the ACL rules.
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func (h *Headscale) LoadACLPolicy(path string) error {
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log.Debug().
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Str("func", "LoadACLPolicy").
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Str("path", path).
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Msg("Loading ACL policy from path")
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policyFile, err := os.Open(path)
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if err != nil {
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return err
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}
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defer policyFile.Close()
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var policy ACLPolicy
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policyBytes, err := io.ReadAll(policyFile)
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if err != nil {
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return err
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}
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switch filepath.Ext(path) {
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case ".yml", ".yaml":
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log.Debug().
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Str("path", path).
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Bytes("file", policyBytes).
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Msg("Loading ACLs from YAML")
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err := yaml.Unmarshal(policyBytes, &policy)
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if err != nil {
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return err
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}
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log.Trace().
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Interface("policy", policy).
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Msg("Loaded policy from YAML")
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default:
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ast, err := hujson.Parse(policyBytes)
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if err != nil {
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return err
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}
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ast.Standardize()
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policyBytes = ast.Pack()
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err = json.Unmarshal(policyBytes, &policy)
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if err != nil {
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return err
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}
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}
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if policy.IsZero() {
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return errEmptyPolicy
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}
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h.aclPolicy = &policy
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return h.UpdateACLRules()
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}
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func (h *Headscale) UpdateACLRules() error {
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machines, err := h.ListMachines()
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if err != nil {
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return err
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}
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if h.aclPolicy == nil {
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return errEmptyPolicy
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}
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rules, err := generateACLRules(machines, *h.aclPolicy, h.cfg.OIDC.StripEmaildomain)
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if err != nil {
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return err
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}
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log.Trace().Interface("ACL", rules).Msg("ACL rules generated")
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h.aclRules = rules
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if featureEnableSSH() {
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sshRules, err := h.generateSSHRules()
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if err != nil {
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return err
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}
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log.Trace().Interface("SSH", sshRules).Msg("SSH rules generated")
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if h.sshPolicy == nil {
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h.sshPolicy = &tailcfg.SSHPolicy{}
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}
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h.sshPolicy.Rules = sshRules
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} else if h.aclPolicy != nil && len(h.aclPolicy.SSHs) > 0 {
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log.Info().Msg("SSH ACLs has been defined, but HEADSCALE_EXPERIMENTAL_FEATURE_SSH is not enabled, this is a unstable feature, check docs before activating")
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}
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return nil
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}
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func generateACLRules(machines []Machine, aclPolicy ACLPolicy, stripEmaildomain bool) ([]tailcfg.FilterRule, error) {
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rules := []tailcfg.FilterRule{}
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for index, acl := range aclPolicy.ACLs {
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if acl.Action != "accept" {
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return nil, errInvalidAction
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}
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srcIPs := []string{}
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for innerIndex, src := range acl.Sources {
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srcs, err := generateACLPolicySrcIP(machines, aclPolicy, src, stripEmaildomain)
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if err != nil {
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log.Error().
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Msgf("Error parsing ACL %d, Source %d", index, innerIndex)
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return nil, err
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}
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srcIPs = append(srcIPs, srcs...)
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}
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protocols, needsWildcard, err := parseProtocol(acl.Protocol)
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if err != nil {
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log.Error().
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Msgf("Error parsing ACL %d. protocol unknown %s", index, acl.Protocol)
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return nil, err
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}
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destPorts := []tailcfg.NetPortRange{}
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for innerIndex, dest := range acl.Destinations {
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dests, err := generateACLPolicyDest(
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machines,
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aclPolicy,
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dest,
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needsWildcard,
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stripEmaildomain,
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)
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if err != nil {
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log.Error().
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Msgf("Error parsing ACL %d, Destination %d", index, innerIndex)
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return nil, err
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}
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destPorts = append(destPorts, dests...)
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}
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rules = append(rules, tailcfg.FilterRule{
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SrcIPs: srcIPs,
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DstPorts: destPorts,
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IPProto: protocols,
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})
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}
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return rules, nil
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}
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func (h *Headscale) generateSSHRules() ([]*tailcfg.SSHRule, error) {
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rules := []*tailcfg.SSHRule{}
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if h.aclPolicy == nil {
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return nil, errEmptyPolicy
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}
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machines, err := h.ListMachines()
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if err != nil {
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return nil, err
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}
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acceptAction := tailcfg.SSHAction{
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Message: "",
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Reject: false,
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Accept: true,
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SessionDuration: 0,
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AllowAgentForwarding: false,
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HoldAndDelegate: "",
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AllowLocalPortForwarding: true,
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}
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rejectAction := tailcfg.SSHAction{
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Message: "",
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Reject: true,
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Accept: false,
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SessionDuration: 0,
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AllowAgentForwarding: false,
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HoldAndDelegate: "",
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AllowLocalPortForwarding: false,
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}
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for index, sshACL := range h.aclPolicy.SSHs {
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action := rejectAction
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switch sshACL.Action {
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case "accept":
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action = acceptAction
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case "check":
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checkAction, err := sshCheckAction(sshACL.CheckPeriod)
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if err != nil {
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log.Error().
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Msgf("Error parsing SSH %d, check action with unparsable duration '%s'", index, sshACL.CheckPeriod)
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} else {
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action = *checkAction
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}
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default:
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log.Error().
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Msgf("Error parsing SSH %d, unknown action '%s'", index, sshACL.Action)
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return nil, err
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}
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principals := make([]*tailcfg.SSHPrincipal, 0, len(sshACL.Sources))
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for innerIndex, rawSrc := range sshACL.Sources {
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expandedSrcs, err := expandAlias(
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machines,
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*h.aclPolicy,
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rawSrc,
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h.cfg.OIDC.StripEmaildomain,
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)
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if err != nil {
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log.Error().
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Msgf("Error parsing SSH %d, Source %d", index, innerIndex)
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return nil, err
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}
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for _, expandedSrc := range expandedSrcs {
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principals = append(principals, &tailcfg.SSHPrincipal{
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NodeIP: expandedSrc,
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})
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}
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}
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userMap := make(map[string]string, len(sshACL.Users))
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for _, user := range sshACL.Users {
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userMap[user] = "="
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}
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rules = append(rules, &tailcfg.SSHRule{
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RuleExpires: nil,
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Principals: principals,
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SSHUsers: userMap,
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Action: &action,
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})
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}
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return rules, nil
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}
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func sshCheckAction(duration string) (*tailcfg.SSHAction, error) {
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sessionLength, err := time.ParseDuration(duration)
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if err != nil {
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return nil, err
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}
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return &tailcfg.SSHAction{
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Message: "",
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Reject: false,
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Accept: true,
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SessionDuration: sessionLength,
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AllowAgentForwarding: false,
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HoldAndDelegate: "",
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AllowLocalPortForwarding: true,
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}, nil
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}
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func generateACLPolicySrcIP(
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machines []Machine,
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aclPolicy ACLPolicy,
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src string,
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stripEmaildomain bool,
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) ([]string, error) {
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return expandAlias(machines, aclPolicy, src, stripEmaildomain)
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}
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func generateACLPolicyDest(
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machines []Machine,
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aclPolicy ACLPolicy,
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dest string,
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needsWildcard bool,
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stripEmaildomain bool,
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) ([]tailcfg.NetPortRange, error) {
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tokens := strings.Split(dest, ":")
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if len(tokens) < expectedTokenItems || len(tokens) > 3 {
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return nil, errInvalidPortFormat
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}
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var alias string
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// We can have here stuff like:
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// git-server:*
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// 192.168.1.0/24:22
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// tag:montreal-webserver:80,443
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// tag:api-server:443
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// example-host-1:*
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if len(tokens) == expectedTokenItems {
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alias = tokens[0]
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} else {
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alias = fmt.Sprintf("%s:%s", tokens[0], tokens[1])
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}
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expanded, err := expandAlias(
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machines,
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aclPolicy,
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alias,
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stripEmaildomain,
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)
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if err != nil {
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return nil, err
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}
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ports, err := expandPorts(tokens[len(tokens)-1], needsWildcard)
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if err != nil {
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return nil, err
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}
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dests := []tailcfg.NetPortRange{}
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for _, d := range expanded {
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for _, p := range *ports {
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pr := tailcfg.NetPortRange{
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IP: d,
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Ports: p,
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}
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dests = append(dests, pr)
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}
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}
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return dests, nil
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}
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// parseProtocol reads the proto field of the ACL and generates a list of
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// protocols that will be allowed, following the IANA IP protocol number
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// https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml
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//
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// If the ACL proto field is empty, it allows ICMPv4, ICMPv6, TCP, and UDP,
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// as per Tailscale behaviour (see tailcfg.FilterRule).
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//
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// Also returns a boolean indicating if the protocol
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// requires all the destinations to use wildcard as port number (only TCP,
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// UDP and SCTP support specifying ports).
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func parseProtocol(protocol string) ([]int, bool, error) {
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switch protocol {
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case "":
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return []int{
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protocolICMP,
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protocolIPv6ICMP,
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protocolTCP,
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protocolUDP,
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}, false, nil
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case "igmp":
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return []int{protocolIGMP}, true, nil
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case "ipv4", "ip-in-ip":
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return []int{protocolIPv4}, true, nil
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case "tcp":
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return []int{protocolTCP}, false, nil
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case "egp":
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return []int{protocolEGP}, true, nil
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case "igp":
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return []int{protocolIGP}, true, nil
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case "udp":
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return []int{protocolUDP}, false, nil
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case "gre":
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return []int{protocolGRE}, true, nil
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case "esp":
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return []int{protocolESP}, true, nil
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case "ah":
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return []int{protocolAH}, true, nil
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case "sctp":
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return []int{protocolSCTP}, false, nil
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case "icmp":
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return []int{protocolICMP, protocolIPv6ICMP}, true, nil
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default:
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protocolNumber, err := strconv.Atoi(protocol)
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if err != nil {
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return nil, false, err
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}
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needsWildcard := protocolNumber != protocolTCP &&
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protocolNumber != protocolUDP &&
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protocolNumber != protocolSCTP
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return []int{protocolNumber}, needsWildcard, nil
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}
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}
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// expandalias has an input of either
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// - a namespace
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// - a group
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// - a tag
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// and transform these in IPAddresses.
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func expandAlias(
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machines []Machine,
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aclPolicy ACLPolicy,
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alias string,
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stripEmailDomain bool,
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) ([]string, error) {
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ips := []string{}
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if alias == "*" {
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return []string{"*"}, nil
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}
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log.Debug().
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Str("alias", alias).
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Msg("Expanding")
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if strings.HasPrefix(alias, "group:") {
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namespaces, err := expandGroup(aclPolicy, alias, stripEmailDomain)
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if err != nil {
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return ips, err
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}
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for _, n := range namespaces {
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nodes := filterMachinesByNamespace(machines, n)
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for _, node := range nodes {
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ips = append(ips, node.IPAddresses.ToStringSlice()...)
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}
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}
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return ips, nil
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}
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if strings.HasPrefix(alias, "tag:") {
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// check for forced tags
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for _, machine := range machines {
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if contains(machine.ForcedTags, alias) {
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ips = append(ips, machine.IPAddresses.ToStringSlice()...)
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}
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}
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// find tag owners
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owners, err := expandTagOwners(aclPolicy, alias, stripEmailDomain)
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if err != nil {
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if errors.Is(err, errInvalidTag) {
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if len(ips) == 0 {
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return ips, fmt.Errorf(
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"%w. %v isn't owned by a TagOwner and no forced tags are defined",
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errInvalidTag,
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alias,
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)
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}
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return ips, nil
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} else {
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return ips, err
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}
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}
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// filter out machines per tag owner
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for _, namespace := range owners {
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machines := filterMachinesByNamespace(machines, namespace)
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for _, machine := range machines {
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hi := machine.GetHostInfo()
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if contains(hi.RequestTags, alias) {
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ips = append(ips, machine.IPAddresses.ToStringSlice()...)
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}
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}
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}
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return ips, nil
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}
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// if alias is a namespace
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nodes := filterMachinesByNamespace(machines, alias)
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nodes = excludeCorrectlyTaggedNodes(aclPolicy, nodes, alias, stripEmailDomain)
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for _, n := range nodes {
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ips = append(ips, n.IPAddresses.ToStringSlice()...)
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}
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if len(ips) > 0 {
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return ips, nil
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}
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// if alias is an host
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if h, ok := aclPolicy.Hosts[alias]; ok {
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return []string{h.String()}, nil
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}
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// if alias is an IP
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ip, err := netip.ParseAddr(alias)
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if err == nil {
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return []string{ip.String()}, nil
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}
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// if alias is an CIDR
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cidr, err := netip.ParsePrefix(alias)
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if err == nil {
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return []string{cidr.String()}, nil
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}
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log.Warn().Msgf("No IPs found with the alias %v", alias)
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return ips, nil
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}
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// excludeCorrectlyTaggedNodes will remove from the list of input nodes the ones
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// that are correctly tagged since they should not be listed as being in the namespace
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// we assume in this function that we only have nodes from 1 namespace.
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func excludeCorrectlyTaggedNodes(
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aclPolicy ACLPolicy,
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nodes []Machine,
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namespace string,
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stripEmailDomain bool,
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) []Machine {
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out := []Machine{}
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tags := []string{}
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for tag := range aclPolicy.TagOwners {
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owners, _ := expandTagOwners(aclPolicy, namespace, stripEmailDomain)
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ns := append(owners, namespace)
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if contains(ns, namespace) {
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tags = append(tags, tag)
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}
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}
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// for each machine if tag is in tags list, don't append it.
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for _, machine := range nodes {
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hi := machine.GetHostInfo()
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found := false
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for _, t := range hi.RequestTags {
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if contains(tags, t) {
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found = true
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break
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}
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}
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if len(machine.ForcedTags) > 0 {
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found = true
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}
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if !found {
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out = append(out, machine)
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}
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}
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return out
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}
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func expandPorts(portsStr string, needsWildcard bool) (*[]tailcfg.PortRange, error) {
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if portsStr == "*" {
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return &[]tailcfg.PortRange{
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{First: portRangeBegin, Last: portRangeEnd},
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}, nil
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}
|
|
|
|
if needsWildcard {
|
|
return nil, errWildcardIsNeeded
|
|
}
|
|
|
|
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,
|
|
stripEmailDomain bool,
|
|
) ([]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, stripEmailDomain)
|
|
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,
|
|
stripEmailDomain bool,
|
|
) ([]string, error) {
|
|
outGroups := []string{}
|
|
aclGroups, ok := aclPolicy.Groups[group]
|
|
if !ok {
|
|
return []string{}, fmt.Errorf(
|
|
"group %v isn't registered. %w",
|
|
group,
|
|
errInvalidGroup,
|
|
)
|
|
}
|
|
for _, group := range aclGroups {
|
|
if strings.HasPrefix(group, "group:") {
|
|
return []string{}, fmt.Errorf(
|
|
"%w. A group cannot be composed of groups. https://tailscale.com/kb/1018/acls/#groups",
|
|
errInvalidGroup,
|
|
)
|
|
}
|
|
grp, err := NormalizeToFQDNRules(group, stripEmailDomain)
|
|
if err != nil {
|
|
return []string{}, fmt.Errorf(
|
|
"failed to normalize group %q, err: %w",
|
|
group,
|
|
errInvalidGroup,
|
|
)
|
|
}
|
|
outGroups = append(outGroups, grp)
|
|
}
|
|
|
|
return outGroups, nil
|
|
}
|