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caddy/modules/caddytls/tls.go
2021-11-02 08:27:25 -06:00

570 lines
19 KiB
Go

// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package caddytls
import (
"crypto/tls"
"encoding/json"
"fmt"
"log"
"net/http"
"runtime/debug"
"sync"
"time"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/certmagic"
"go.uber.org/zap"
)
func init() {
caddy.RegisterModule(TLS{})
caddy.RegisterModule(AutomateLoader{})
}
// TLS provides TLS facilities including certificate
// loading and management, client auth, and more.
type TLS struct {
// Caches certificates in memory for quick use during
// TLS handshakes. Each key is the name of a certificate
// loader module. All loaded certificates get pooled
// into the same cache and may be used to complete TLS
// handshakes for the relevant server names (SNI).
// Certificates loaded manually (anything other than
// "automate") are not automatically managed and will
// have to be refreshed manually before they expire.
CertificatesRaw caddy.ModuleMap `json:"certificates,omitempty" caddy:"namespace=tls.certificates"`
// Configures certificate automation.
Automation *AutomationConfig `json:"automation,omitempty"`
// Configures session ticket ephemeral keys (STEKs).
SessionTickets *SessionTicketService `json:"session_tickets,omitempty"`
// Configures the in-memory certificate cache.
Cache *CertCacheOptions `json:"cache,omitempty"`
// Disables OCSP stapling for manually-managed certificates only.
// To configure OCSP stapling for automated certificates, use an
// automation policy instead.
//
// Disabling OCSP stapling puts clients at greater risk, reduces their
// privacy, and usually lowers client performance. It is NOT recommended
// to disable this unless you are able to justify the costs.
// EXPERIMENTAL. Subject to change.
DisableOCSPStapling bool `json:"disable_ocsp_stapling,omitempty"`
certificateLoaders []CertificateLoader
automateNames []string
certCache *certmagic.Cache
ctx caddy.Context
storageCleanTicker *time.Ticker
storageCleanStop chan struct{}
logger *zap.Logger
}
// CaddyModule returns the Caddy module information.
func (TLS) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "tls",
New: func() caddy.Module { return new(TLS) },
}
}
// Provision sets up the configuration for the TLS app.
func (t *TLS) Provision(ctx caddy.Context) error {
t.ctx = ctx
t.logger = ctx.Logger(t)
repl := caddy.NewReplacer()
// set up a new certificate cache; this (re)loads all certificates
cacheOpts := certmagic.CacheOptions{
GetConfigForCert: func(cert certmagic.Certificate) (*certmagic.Config, error) {
return t.getConfigForName(cert.Names[0]), nil
},
Logger: t.logger.Named("cache"),
}
if t.Automation != nil {
cacheOpts.OCSPCheckInterval = time.Duration(t.Automation.OCSPCheckInterval)
cacheOpts.RenewCheckInterval = time.Duration(t.Automation.RenewCheckInterval)
}
if t.Cache != nil {
cacheOpts.Capacity = t.Cache.Capacity
}
if cacheOpts.Capacity <= 0 {
cacheOpts.Capacity = 10000
}
t.certCache = certmagic.NewCache(cacheOpts)
// certificate loaders
val, err := ctx.LoadModule(t, "CertificatesRaw")
if err != nil {
return fmt.Errorf("loading certificate loader modules: %s", err)
}
for modName, modIface := range val.(map[string]interface{}) {
if modName == "automate" {
// special case; these will be loaded in later using our automation facilities,
// which we want to avoid doing during provisioning
if automateNames, ok := modIface.(*AutomateLoader); ok && automateNames != nil {
t.automateNames = []string(*automateNames)
} else {
return fmt.Errorf("loading certificates with 'automate' requires array of strings, got: %T", modIface)
}
continue
}
t.certificateLoaders = append(t.certificateLoaders, modIface.(CertificateLoader))
}
// automation/management policies
if t.Automation == nil {
t.Automation = new(AutomationConfig)
}
t.Automation.defaultPublicAutomationPolicy = new(AutomationPolicy)
err = t.Automation.defaultPublicAutomationPolicy.Provision(t)
if err != nil {
return fmt.Errorf("provisioning default public automation policy: %v", err)
}
for _, n := range t.automateNames {
// if any names specified by the "automate" loader do not qualify for a public
// certificate, we should initialize a default internal automation policy
// (but we don't want to do this unnecessarily, since it may prompt for password!)
if certmagic.SubjectQualifiesForPublicCert(n) {
continue
}
t.Automation.defaultInternalAutomationPolicy = &AutomationPolicy{
IssuersRaw: []json.RawMessage{json.RawMessage(`{"module":"internal"}`)},
}
err = t.Automation.defaultInternalAutomationPolicy.Provision(t)
if err != nil {
return fmt.Errorf("provisioning default internal automation policy: %v", err)
}
break
}
for i, ap := range t.Automation.Policies {
err := ap.Provision(t)
if err != nil {
return fmt.Errorf("provisioning automation policy %d: %v", i, err)
}
}
// session ticket ephemeral keys (STEK) service and provider
if t.SessionTickets != nil {
err := t.SessionTickets.provision(ctx)
if err != nil {
return fmt.Errorf("provisioning session tickets configuration: %v", err)
}
}
// on-demand rate limiting
if t.Automation != nil && t.Automation.OnDemand != nil && t.Automation.OnDemand.RateLimit != nil {
onDemandRateLimiter.SetMaxEvents(t.Automation.OnDemand.RateLimit.Burst)
onDemandRateLimiter.SetWindow(time.Duration(t.Automation.OnDemand.RateLimit.Interval))
} else {
// remove any existing rate limiter
onDemandRateLimiter.SetMaxEvents(0)
onDemandRateLimiter.SetWindow(0)
}
// run replacer on ask URL (for environment variables)
if t.Automation != nil && t.Automation.OnDemand != nil && t.Automation.OnDemand.Ask != "" {
t.Automation.OnDemand.Ask = repl.ReplaceAll(t.Automation.OnDemand.Ask, "")
}
// load manual/static (unmanaged) certificates - we do this in
// provision so that other apps (such as http) can know which
// certificates have been manually loaded, and also so that
// commands like validate can be a better test
magic := certmagic.New(t.certCache, certmagic.Config{
Storage: ctx.Storage(),
Logger: t.logger,
OCSP: certmagic.OCSPConfig{
DisableStapling: t.DisableOCSPStapling,
},
})
for _, loader := range t.certificateLoaders {
certs, err := loader.LoadCertificates()
if err != nil {
return fmt.Errorf("loading certificates: %v", err)
}
for _, cert := range certs {
err := magic.CacheUnmanagedTLSCertificate(cert.Certificate, cert.Tags)
if err != nil {
return fmt.Errorf("caching unmanaged certificate: %v", err)
}
}
}
return nil
}
// Validate validates t's configuration.
func (t *TLS) Validate() error {
if t.Automation != nil {
// ensure that host aren't repeated; since only the first
// automation policy is used, repeating a host in the lists
// isn't useful and is probably a mistake; same for two
// catch-all/default policies
var hasDefault bool
hostSet := make(map[string]int)
for i, ap := range t.Automation.Policies {
if len(ap.Subjects) == 0 {
if hasDefault {
return fmt.Errorf("automation policy %d is the second policy that acts as default/catch-all, but will never be used", i)
}
hasDefault = true
}
for _, h := range ap.Subjects {
if first, ok := hostSet[h]; ok {
return fmt.Errorf("automation policy %d: cannot apply more than one automation policy to host: %s (first match in policy %d)", i, h, first)
}
hostSet[h] = i
}
}
}
if t.Cache != nil {
if t.Cache.Capacity < 0 {
return fmt.Errorf("cache capacity must be >= 0")
}
}
return nil
}
// Start activates the TLS module.
func (t *TLS) Start() error {
// warn if on-demand TLS is enabled but no restrictions are in place
if t.Automation.OnDemand == nil ||
(t.Automation.OnDemand.Ask == "" && t.Automation.OnDemand.RateLimit == nil) {
for _, ap := range t.Automation.Policies {
if ap.OnDemand {
t.logger.Warn("YOUR SERVER MAY BE VULNERABLE TO ABUSE: on-demand TLS is enabled, but no protections are in place",
zap.String("docs", "https://caddyserver.com/docs/automatic-https#on-demand-tls"))
break
}
}
}
// now that we are running, and all manual certificates have
// been loaded, time to load the automated/managed certificates
err := t.Manage(t.automateNames)
if err != nil {
return fmt.Errorf("automate: managing %v: %v", t.automateNames, err)
}
t.keepStorageClean()
return nil
}
// Stop stops the TLS module and cleans up any allocations.
func (t *TLS) Stop() error {
// stop the storage cleaner goroutine and ticker
if t.storageCleanStop != nil {
close(t.storageCleanStop)
}
if t.storageCleanTicker != nil {
t.storageCleanTicker.Stop()
}
return nil
}
// Cleanup frees up resources allocated during Provision.
func (t *TLS) Cleanup() error {
// stop the certificate cache
if t.certCache != nil {
t.certCache.Stop()
}
// stop the session ticket rotation goroutine
if t.SessionTickets != nil {
t.SessionTickets.stop()
}
return nil
}
// Manage immediately begins managing names according to the
// matching automation policy.
func (t *TLS) Manage(names []string) error {
// for a large number of names, we can be more memory-efficient
// by making only one certmagic.Config for all the names that
// use that config, rather than calling ManageAsync once for
// every name; so first, bin names by AutomationPolicy
policyToNames := make(map[*AutomationPolicy][]string)
for _, name := range names {
ap := t.getAutomationPolicyForName(name)
policyToNames[ap] = append(policyToNames[ap], name)
}
// now that names are grouped by policy, we can simply make one
// certmagic.Config for each (potentially large) group of names
// and call ManageAsync just once for the whole batch
for ap, names := range policyToNames {
err := ap.magic.ManageAsync(t.ctx.Context, names)
if err != nil {
return fmt.Errorf("automate: manage %v: %v", names, err)
}
}
return nil
}
// HandleHTTPChallenge ensures that the HTTP challenge is handled for the
// certificate named by r.Host, if it is an HTTP challenge request. It
// requires that the automation policy for r.Host has an issuer of type
// *certmagic.ACMEManager, or one that is ACME-enabled (GetACMEIssuer()).
func (t *TLS) HandleHTTPChallenge(w http.ResponseWriter, r *http.Request) bool {
// no-op if it's not an ACME challenge request
if !certmagic.LooksLikeHTTPChallenge(r) {
return false
}
// try all the issuers until we find the one that initiated the challenge
ap := t.getAutomationPolicyForName(r.Host)
type acmeCapable interface{ GetACMEIssuer() *ACMEIssuer }
for _, iss := range ap.magic.Issuers {
if am, ok := iss.(acmeCapable); ok {
iss := am.GetACMEIssuer()
if certmagic.NewACMEManager(iss.magic, iss.template).HandleHTTPChallenge(w, r) {
return true
}
}
}
// it's possible another server in this process initiated the challenge;
// users have requested that Caddy only handle HTTP challenges it initiated,
// so that users can proxy the others through to their backends; but we
// might not have an automation policy for all identifiers that are trying
// to get certificates (e.g. the admin endpoint), so we do this manual check
if challenge, ok := certmagic.GetACMEChallenge(r.Host); ok {
return certmagic.SolveHTTPChallenge(t.logger, w, r, challenge.Challenge)
}
return false
}
// AddAutomationPolicy provisions and adds ap to the list of the app's
// automation policies. If an existing automation policy exists that has
// fewer hosts in its list than ap does, ap will be inserted before that
// other policy (this helps ensure that ap will be prioritized/chosen
// over, say, a catch-all policy).
func (t *TLS) AddAutomationPolicy(ap *AutomationPolicy) error {
if t.Automation == nil {
t.Automation = new(AutomationConfig)
}
err := ap.Provision(t)
if err != nil {
return err
}
// sort new automation policies just before any other which is a superset
// of this one; if we find an existing policy that covers every subject in
// ap but less specifically (e.g. a catch-all policy, or one with wildcards
// or with fewer subjects), insert ap just before it, otherwise ap would
// never be used because the first matching policy is more general
for i, existing := range t.Automation.Policies {
// first see if existing is superset of ap for all names
var otherIsSuperset bool
outer:
for _, thisSubj := range ap.Subjects {
for _, otherSubj := range existing.Subjects {
if certmagic.MatchWildcard(thisSubj, otherSubj) {
otherIsSuperset = true
break outer
}
}
}
// if existing AP is a superset or if it contains fewer names (i.e. is
// more general), then new AP is more specific, so insert before it
if otherIsSuperset || len(existing.Subjects) < len(ap.Subjects) {
t.Automation.Policies = append(t.Automation.Policies[:i],
append([]*AutomationPolicy{ap}, t.Automation.Policies[i:]...)...)
return nil
}
}
// otherwise just append the new one
t.Automation.Policies = append(t.Automation.Policies, ap)
return nil
}
func (t *TLS) getConfigForName(name string) *certmagic.Config {
ap := t.getAutomationPolicyForName(name)
return ap.magic
}
// getAutomationPolicyForName returns the first matching automation policy
// for the given subject name. If no matching policy can be found, the
// default policy is used, depending on whether the name qualifies for a
// public certificate or not.
func (t *TLS) getAutomationPolicyForName(name string) *AutomationPolicy {
for _, ap := range t.Automation.Policies {
if len(ap.Subjects) == 0 {
return ap // no host filter is an automatic match
}
for _, h := range ap.Subjects {
if certmagic.MatchWildcard(name, h) {
return ap
}
}
}
if certmagic.SubjectQualifiesForPublicCert(name) || t.Automation.defaultInternalAutomationPolicy == nil {
return t.Automation.defaultPublicAutomationPolicy
}
return t.Automation.defaultInternalAutomationPolicy
}
// AllMatchingCertificates returns the list of all certificates in
// the cache which could be used to satisfy the given SAN.
func (t *TLS) AllMatchingCertificates(san string) []certmagic.Certificate {
return t.certCache.AllMatchingCertificates(san)
}
// keepStorageClean starts a goroutine that immediately cleans up all
// known storage units if it was not recently done, and then runs the
// operation at every tick from t.storageCleanTicker.
func (t *TLS) keepStorageClean() {
t.storageCleanTicker = time.NewTicker(t.storageCleanInterval())
t.storageCleanStop = make(chan struct{})
go func() {
defer func() {
if err := recover(); err != nil {
log.Printf("[PANIC] storage cleaner: %v\n%s", err, debug.Stack())
}
}()
t.cleanStorageUnits()
for {
select {
case <-t.storageCleanStop:
return
case <-t.storageCleanTicker.C:
t.cleanStorageUnits()
}
}
}()
}
func (t *TLS) cleanStorageUnits() {
storageCleanMu.Lock()
defer storageCleanMu.Unlock()
// If storage was cleaned recently, don't do it again for now. Although the ticker
// calling this function drops missed ticks for us, config reloads discard the old
// ticker and replace it with a new one, possibly invoking a cleaning to happen again
// too soon. (We divide the interval by 2 because the actual cleaning takes non-zero
// time, and we don't want to skip cleanings if we don't have to; whereas if a cleaning
// took most of the interval, we'd probably want to skip the next one so we aren't
// constantly cleaning. This allows cleanings to take up to half the interval's
// duration before we decide to skip the next one.)
if !storageClean.IsZero() && time.Since(storageClean) < t.storageCleanInterval()/2 {
return
}
options := certmagic.CleanStorageOptions{
OCSPStaples: true,
ExpiredCerts: true,
ExpiredCertGracePeriod: 24 * time.Hour * 14,
}
// avoid cleaning same storage more than once per cleaning cycle
storagesCleaned := make(map[string]struct{})
// start with the default/global storage
storage := t.ctx.Storage()
storageStr := fmt.Sprintf("%v", storage)
t.logger.Info("cleaning storage unit", zap.String("description", storageStr))
certmagic.CleanStorage(t.ctx, storage, options)
storagesCleaned[storageStr] = struct{}{}
// then clean each storage defined in ACME automation policies
if t.Automation != nil {
for _, ap := range t.Automation.Policies {
if ap.storage == nil {
continue
}
storageStr := fmt.Sprintf("%v", ap.storage)
if _, ok := storagesCleaned[storageStr]; ok {
continue
}
t.logger.Info("cleaning storage unit", zap.String("description", storageStr))
certmagic.CleanStorage(t.ctx, ap.storage, options)
storagesCleaned[storageStr] = struct{}{}
}
}
// remember last time storage was finished cleaning
storageClean = time.Now()
t.logger.Info("finished cleaning storage units")
}
func (t *TLS) storageCleanInterval() time.Duration {
if t.Automation != nil && t.Automation.StorageCleanInterval > 0 {
return time.Duration(t.Automation.StorageCleanInterval)
}
return defaultStorageCleanInterval
}
// CertificateLoader is a type that can load certificates.
// Certificates can optionally be associated with tags.
type CertificateLoader interface {
LoadCertificates() ([]Certificate, error)
}
// Certificate is a TLS certificate, optionally
// associated with arbitrary tags.
type Certificate struct {
tls.Certificate
Tags []string
}
// AutomateLoader will automatically manage certificates for the names in the
// list, including obtaining and renewing certificates. Automated certificates
// are managed according to their matching automation policy, configured
// elsewhere in this app.
//
// Technically, this is a no-op certificate loader module that is treated as
// a special case: it uses this app's automation features to load certificates
// for the list of hostnames, rather than loading certificates manually.
type AutomateLoader []string
// CaddyModule returns the Caddy module information.
func (AutomateLoader) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "tls.certificates.automate",
New: func() caddy.Module { return new(AutomateLoader) },
}
}
// CertCacheOptions configures the certificate cache.
type CertCacheOptions struct {
// Maximum number of certificates to allow in the
// cache. If reached, certificates will be randomly
// evicted to make room for new ones. Default: 10,000
Capacity int `json:"capacity,omitempty"`
}
// Variables related to storage cleaning.
var (
defaultStorageCleanInterval = 24 * time.Hour
storageClean time.Time
storageCleanMu sync.Mutex
)
// Interface guards
var (
_ caddy.App = (*TLS)(nil)
_ caddy.Provisioner = (*TLS)(nil)
_ caddy.Validator = (*TLS)(nil)
_ caddy.CleanerUpper = (*TLS)(nil)
)