package certificates import ( "bytes" "context" "crypto/ecdsa" "crypto/elliptic" "crypto/rand" "crypto/tls" "crypto/x509" "encoding/gob" "encoding/json" "errors" "fmt" "os" "strconv" "strings" "sync" "time" "github.com/go-acme/lego/v4/certcrypto" "github.com/go-acme/lego/v4/certificate" "github.com/go-acme/lego/v4/challenge" "github.com/go-acme/lego/v4/challenge/tlsalpn01" "github.com/go-acme/lego/v4/lego" "github.com/go-acme/lego/v4/providers/dns" "github.com/go-acme/lego/v4/registration" "github.com/reugn/equalizer" "github.com/rs/zerolog/log" "codeberg.org/codeberg/pages/server/cache" "codeberg.org/codeberg/pages/server/database" dnsutils "codeberg.org/codeberg/pages/server/dns" "codeberg.org/codeberg/pages/server/gitea" "codeberg.org/codeberg/pages/server/upstream" ) // TLSConfig returns the configuration for generating, serving and cleaning up Let's Encrypt certificates. func TLSConfig(mainDomainSuffix string, giteaClient *gitea.Client, dnsProvider string, acmeUseRateLimits bool, keyCache, challengeCache, dnsLookupCache, canonicalDomainCache cache.SetGetKey, certDB database.CertDB, ) *tls.Config { return &tls.Config{ // check DNS name & get certificate from Let's Encrypt GetCertificate: func(info *tls.ClientHelloInfo) (*tls.Certificate, error) { sni := strings.ToLower(strings.TrimSpace(info.ServerName)) if len(sni) < 1 { return nil, errors.New("missing sni") } if info.SupportedProtos != nil { for _, proto := range info.SupportedProtos { if proto != tlsalpn01.ACMETLS1Protocol { continue } challenge, ok := challengeCache.Get(sni) if !ok { return nil, errors.New("no challenge for this domain") } cert, err := tlsalpn01.ChallengeCert(sni, challenge.(string)) if err != nil { return nil, err } return cert, nil } } targetOwner := "" mayObtainCert := true if strings.HasSuffix(sni, mainDomainSuffix) || strings.EqualFold(sni, mainDomainSuffix[1:]) { // deliver default certificate for the main domain (*.codeberg.page) sni = mainDomainSuffix } else { var targetRepo, targetBranch string targetOwner, targetRepo, targetBranch = dnsutils.GetTargetFromDNS(sni, mainDomainSuffix, dnsLookupCache) if targetOwner == "" { // DNS not set up, return main certificate to redirect to the docs sni = mainDomainSuffix } else { targetOpt := &upstream.Options{ TargetOwner: targetOwner, TargetRepo: targetRepo, TargetBranch: targetBranch, } _, valid := targetOpt.CheckCanonicalDomain(giteaClient, sni, mainDomainSuffix, canonicalDomainCache) if !valid { // We shouldn't obtain a certificate when we cannot check if the // repository has specified this domain in the `.domains` file. mayObtainCert = false } } } if tlsCertificate, ok := keyCache.Get(sni); ok { // we can use an existing certificate object return tlsCertificate.(*tls.Certificate), nil } var tlsCertificate tls.Certificate var err error var ok bool if tlsCertificate, ok = retrieveCertFromDB(sni, mainDomainSuffix, dnsProvider, acmeUseRateLimits, certDB); !ok { // request a new certificate if strings.EqualFold(sni, mainDomainSuffix) { return nil, errors.New("won't request certificate for main domain, something really bad has happened") } if !mayObtainCert { return nil, fmt.Errorf("won't request certificate for %q", sni) } tlsCertificate, err = obtainCert(acmeClient, []string{sni}, nil, targetOwner, dnsProvider, mainDomainSuffix, acmeUseRateLimits, certDB) if err != nil { return nil, err } } if err := keyCache.Set(sni, &tlsCertificate, 15*time.Minute); err != nil { return nil, err } return &tlsCertificate, nil }, PreferServerCipherSuites: true, NextProtos: []string{ "h2", "http/1.1", tlsalpn01.ACMETLS1Protocol, }, // generated 2021-07-13, Mozilla Guideline v5.6, Go 1.14.4, intermediate configuration // https://ssl-config.mozilla.org/#server=go&version=1.14.4&config=intermediate&guideline=5.6 MinVersion: tls.VersionTLS12, CipherSuites: []uint16{ tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384, tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, }, } } func checkUserLimit(user string) error { userLimit, ok := acmeClientCertificateLimitPerUser[user] if !ok { // Each Codeberg user can only add 10 new domains per day. userLimit = equalizer.NewTokenBucket(10, time.Hour*24) acmeClientCertificateLimitPerUser[user] = userLimit } if !userLimit.Ask() { return errors.New("rate limit exceeded: 10 certificates per user per 24 hours") } return nil } var ( acmeClient, mainDomainAcmeClient *lego.Client acmeClientCertificateLimitPerUser = map[string]*equalizer.TokenBucket{} ) // rate limit is 300 / 3 hours, we want 200 / 2 hours but to refill more often, so that's 25 new domains every 15 minutes // TODO: when this is used a lot, we probably have to think of a somewhat better solution? var acmeClientOrderLimit = equalizer.NewTokenBucket(25, 15*time.Minute) // rate limit is 20 / second, we want 5 / second (especially as one cert takes at least two requests) var acmeClientRequestLimit = equalizer.NewTokenBucket(5, 1*time.Second) // rate limit is 5 / hour https://letsencrypt.org/docs/failed-validation-limit/ var acmeClientFailLimit = equalizer.NewTokenBucket(5, 1*time.Hour) type AcmeTLSChallengeProvider struct { challengeCache cache.SetGetKey } // make sure AcmeTLSChallengeProvider match Provider interface var _ challenge.Provider = AcmeTLSChallengeProvider{} func (a AcmeTLSChallengeProvider) Present(domain, _, keyAuth string) error { return a.challengeCache.Set(domain, keyAuth, 1*time.Hour) } func (a AcmeTLSChallengeProvider) CleanUp(domain, _, _ string) error { a.challengeCache.Remove(domain) return nil } type AcmeHTTPChallengeProvider struct { challengeCache cache.SetGetKey } // make sure AcmeHTTPChallengeProvider match Provider interface var _ challenge.Provider = AcmeHTTPChallengeProvider{} func (a AcmeHTTPChallengeProvider) Present(domain, token, keyAuth string) error { return a.challengeCache.Set(domain+"/"+token, keyAuth, 1*time.Hour) } func (a AcmeHTTPChallengeProvider) CleanUp(domain, token, _ string) error { a.challengeCache.Remove(domain + "/" + token) return nil } func retrieveCertFromDB(sni, mainDomainSuffix, dnsProvider string, acmeUseRateLimits bool, certDB database.CertDB) (tls.Certificate, bool) { // parse certificate from database res, err := certDB.Get(sni) if err != nil { panic(err) // TODO: no panic } if res == nil { return tls.Certificate{}, false } tlsCertificate, err := tls.X509KeyPair(res.Certificate, res.PrivateKey) if err != nil { panic(err) } // TODO: document & put into own function if !strings.EqualFold(sni, mainDomainSuffix) { tlsCertificate.Leaf, err = x509.ParseCertificate(tlsCertificate.Certificate[0]) if err != nil { panic(err) } // renew certificates 7 days before they expire if tlsCertificate.Leaf.NotAfter.Before(time.Now().Add(7 * 24 * time.Hour)) { // TODO: add ValidUntil to custom res struct if res.CSR != nil && len(res.CSR) > 0 { // CSR stores the time when the renewal shall be tried again nextTryUnix, err := strconv.ParseInt(string(res.CSR), 10, 64) if err == nil && time.Now().Before(time.Unix(nextTryUnix, 0)) { return tlsCertificate, true } } go (func() { res.CSR = nil // acme client doesn't like CSR to be set tlsCertificate, err = obtainCert(acmeClient, []string{sni}, res, "", dnsProvider, mainDomainSuffix, acmeUseRateLimits, certDB) if err != nil { log.Error().Msgf("Couldn't renew certificate for %s: %v", sni, err) } })() } } return tlsCertificate, true } var obtainLocks = sync.Map{} func obtainCert(acmeClient *lego.Client, domains []string, renew *certificate.Resource, user, dnsProvider, mainDomainSuffix string, acmeUseRateLimits bool, keyDatabase database.CertDB) (tls.Certificate, error) { name := strings.TrimPrefix(domains[0], "*") if dnsProvider == "" && len(domains[0]) > 0 && domains[0][0] == '*' { domains = domains[1:] } // lock to avoid simultaneous requests _, working := obtainLocks.LoadOrStore(name, struct{}{}) if working { for working { time.Sleep(100 * time.Millisecond) _, working = obtainLocks.Load(name) } cert, ok := retrieveCertFromDB(name, mainDomainSuffix, dnsProvider, acmeUseRateLimits, keyDatabase) if !ok { return tls.Certificate{}, errors.New("certificate failed in synchronous request") } return cert, nil } defer obtainLocks.Delete(name) if acmeClient == nil { return mockCert(domains[0], "ACME client uninitialized. This is a server error, please report!", mainDomainSuffix, keyDatabase), nil } // request actual cert var res *certificate.Resource var err error if renew != nil && renew.CertURL != "" { if acmeUseRateLimits { acmeClientRequestLimit.Take() } log.Debug().Msgf("Renewing certificate for: %v", domains) res, err = acmeClient.Certificate.Renew(*renew, true, false, "") if err != nil { log.Error().Err(err).Msgf("Couldn't renew certificate for %v, trying to request a new one", domains) if acmeUseRateLimits { acmeClientFailLimit.Take() } res = nil } } if res == nil { if user != "" { if err := checkUserLimit(user); err != nil { return tls.Certificate{}, err } } if acmeUseRateLimits { acmeClientOrderLimit.Take() acmeClientRequestLimit.Take() } log.Debug().Msgf("Re-requesting new certificate for %v", domains) res, err = acmeClient.Certificate.Obtain(certificate.ObtainRequest{ Domains: domains, Bundle: true, MustStaple: false, }) if acmeUseRateLimits && err != nil { acmeClientFailLimit.Take() } } if err != nil { log.Error().Err(err).Msgf("Couldn't obtain again a certificate or %v", domains) if renew != nil && renew.CertURL != "" { tlsCertificate, err := tls.X509KeyPair(renew.Certificate, renew.PrivateKey) if err != nil { return mockCert(domains[0], err.Error(), mainDomainSuffix, keyDatabase), err } leaf, err := leaf(&tlsCertificate) if err == nil && leaf.NotAfter.After(time.Now()) { // avoid sending a mock cert instead of a still valid cert, instead abuse CSR field to store time to try again at renew.CSR = []byte(strconv.FormatInt(time.Now().Add(6*time.Hour).Unix(), 10)) if err := keyDatabase.Put(name, renew); err != nil { return mockCert(domains[0], err.Error(), mainDomainSuffix, keyDatabase), err } return tlsCertificate, nil } } return mockCert(domains[0], err.Error(), mainDomainSuffix, keyDatabase), err } log.Debug().Msgf("Obtained certificate for %v", domains) if err := keyDatabase.Put(name, res); err != nil { return tls.Certificate{}, err } tlsCertificate, err := tls.X509KeyPair(res.Certificate, res.PrivateKey) if err != nil { return tls.Certificate{}, err } return tlsCertificate, nil } func SetupAcmeConfig(acmeAPI, acmeMail, acmeEabHmac, acmeEabKID string, acmeAcceptTerms bool) (*lego.Config, error) { const configFile = "acme-account.json" var myAcmeAccount AcmeAccount var myAcmeConfig *lego.Config if account, err := os.ReadFile(configFile); err == nil { if err := json.Unmarshal(account, &myAcmeAccount); err != nil { return nil, err } myAcmeAccount.Key, err = certcrypto.ParsePEMPrivateKey([]byte(myAcmeAccount.KeyPEM)) if err != nil { return nil, err } myAcmeConfig = lego.NewConfig(&myAcmeAccount) myAcmeConfig.CADirURL = acmeAPI myAcmeConfig.Certificate.KeyType = certcrypto.RSA2048 // Validate Config _, err := lego.NewClient(myAcmeConfig) if err != nil { // TODO: should we fail hard instead? log.Error().Err(err).Msg("Can't create ACME client, continuing with mock certs only") } return myAcmeConfig, nil } else if !os.IsNotExist(err) { return nil, err } privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader) if err != nil { return nil, err } myAcmeAccount = AcmeAccount{ Email: acmeMail, Key: privateKey, KeyPEM: string(certcrypto.PEMEncode(privateKey)), } myAcmeConfig = lego.NewConfig(&myAcmeAccount) myAcmeConfig.CADirURL = acmeAPI myAcmeConfig.Certificate.KeyType = certcrypto.RSA2048 tempClient, err := lego.NewClient(myAcmeConfig) if err != nil { log.Error().Err(err).Msg("Can't create ACME client, continuing with mock certs only") } else { // accept terms & log in to EAB if acmeEabKID == "" || acmeEabHmac == "" { reg, err := tempClient.Registration.Register(registration.RegisterOptions{TermsOfServiceAgreed: acmeAcceptTerms}) if err != nil { log.Error().Err(err).Msg("Can't register ACME account, continuing with mock certs only") } else { myAcmeAccount.Registration = reg } } else { reg, err := tempClient.Registration.RegisterWithExternalAccountBinding(registration.RegisterEABOptions{ TermsOfServiceAgreed: acmeAcceptTerms, Kid: acmeEabKID, HmacEncoded: acmeEabHmac, }) if err != nil { log.Error().Err(err).Msg("Can't register ACME account, continuing with mock certs only") } else { myAcmeAccount.Registration = reg } } if myAcmeAccount.Registration != nil { acmeAccountJSON, err := json.Marshal(myAcmeAccount) if err != nil { log.Error().Err(err).Msg("json.Marshalfailed, waiting for manual restart to avoid rate limits") select {} } err = os.WriteFile(configFile, acmeAccountJSON, 0o600) if err != nil { log.Error().Err(err).Msg("os.WriteFile failed, waiting for manual restart to avoid rate limits") select {} } } } return myAcmeConfig, nil } func SetupCertificates(mainDomainSuffix, dnsProvider string, acmeConfig *lego.Config, acmeUseRateLimits, enableHTTPServer bool, challengeCache cache.SetGetKey, certDB database.CertDB) error { // getting main cert before ACME account so that we can fail here without hitting rate limits mainCertBytes, err := certDB.Get(mainDomainSuffix) if err != nil { return fmt.Errorf("cert database is not working") } acmeClient, err = lego.NewClient(acmeConfig) if err != nil { log.Fatal().Err(err).Msg("Can't create ACME client, continuing with mock certs only") } else { err = acmeClient.Challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{challengeCache}) if err != nil { log.Error().Err(err).Msg("Can't create TLS-ALPN-01 provider") } if enableHTTPServer { err = acmeClient.Challenge.SetHTTP01Provider(AcmeHTTPChallengeProvider{challengeCache}) if err != nil { log.Error().Err(err).Msg("Can't create HTTP-01 provider") } } } mainDomainAcmeClient, err = lego.NewClient(acmeConfig) if err != nil { log.Error().Err(err).Msg("Can't create ACME client, continuing with mock certs only") } else { if dnsProvider == "" { // using mock server, don't use wildcard certs err := mainDomainAcmeClient.Challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{challengeCache}) if err != nil { log.Error().Err(err).Msg("Can't create TLS-ALPN-01 provider") } } else { provider, err := dns.NewDNSChallengeProviderByName(dnsProvider) if err != nil { log.Error().Err(err).Msg("Can't create DNS Challenge provider") } err = mainDomainAcmeClient.Challenge.SetDNS01Provider(provider) if err != nil { log.Error().Err(err).Msg("Can't create DNS-01 provider") } } } if mainCertBytes == nil { _, err = obtainCert(mainDomainAcmeClient, []string{"*" + mainDomainSuffix, mainDomainSuffix[1:]}, nil, "", dnsProvider, mainDomainSuffix, acmeUseRateLimits, certDB) if err != nil { log.Error().Err(err).Msg("Couldn't renew main domain certificate, continuing with mock certs only") } } return nil } func MaintainCertDB(ctx context.Context, interval time.Duration, mainDomainSuffix, dnsProvider string, acmeUseRateLimits bool, certDB database.CertDB) { for { // clean up expired certs now := time.Now() expiredCertCount := 0 keyDatabaseIterator := certDB.Items() key, resBytes, err := keyDatabaseIterator.Next() for err == nil { if !strings.EqualFold(string(key), mainDomainSuffix) { resGob := bytes.NewBuffer(resBytes) resDec := gob.NewDecoder(resGob) res := &certificate.Resource{} err = resDec.Decode(res) if err != nil { panic(err) } tlsCertificates, err := certcrypto.ParsePEMBundle(res.Certificate) if err != nil || tlsCertificates[0].NotAfter.Before(now) { err := certDB.Delete(string(key)) if err != nil { log.Error().Err(err).Msgf("Deleting expired certificate for %q failed", string(key)) } else { expiredCertCount++ } } } key, resBytes, err = keyDatabaseIterator.Next() } log.Debug().Msgf("Removed %d expired certificates from the database", expiredCertCount) // compact the database msg, err := certDB.Compact() if err != nil { log.Error().Err(err).Msg("Compacting key database failed") } else { log.Debug().Msgf("Compacted key database: %s", msg) } // update main cert res, err := certDB.Get(mainDomainSuffix) if err != nil { log.Error().Msgf("Couldn't get cert for domain %q", mainDomainSuffix) } else if res == nil { log.Error().Msgf("Couldn't renew certificate for main domain %q expected main domain cert to exist, but it's missing - seems like the database is corrupted", mainDomainSuffix) } else { tlsCertificates, err := certcrypto.ParsePEMBundle(res.Certificate) // renew main certificate 30 days before it expires if tlsCertificates[0].NotAfter.Before(time.Now().Add(30 * 24 * time.Hour)) { go (func() { _, err = obtainCert(mainDomainAcmeClient, []string{"*" + mainDomainSuffix, mainDomainSuffix[1:]}, res, "", dnsProvider, mainDomainSuffix, acmeUseRateLimits, certDB) if err != nil { log.Error().Err(err).Msg("Couldn't renew certificate for main domain") } })() } } select { case <-ctx.Done(): return case <-time.After(interval): } } } // leaf returns the parsed leaf certificate, either from c.leaf or by parsing // the corresponding c.Certificate[0]. func leaf(c *tls.Certificate) (*x509.Certificate, error) { if c.Leaf != nil { return c.Leaf, nil } return x509.ParseCertificate(c.Certificate[0]) }