pages-server/server/certificates.go
2021-12-05 15:02:44 +01:00

596 lines
19 KiB
Go

package server
import (
"bytes"
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/gob"
"encoding/json"
"encoding/pem"
"errors"
"io/ioutil"
"log"
"math/big"
"os"
"strconv"
"strings"
"sync"
"time"
"github.com/reugn/equalizer"
"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"
"codeberg.org/codeberg/pages/server/cache"
"codeberg.org/codeberg/pages/server/database"
)
// TLSConfig returns the configuration for generating, serving and cleaning up Let's Encrypt certificates.
func TLSConfig(mainDomainSuffix []byte,
giteaRoot, giteaApiToken, dnsProvider string,
acmeUseRateLimits bool,
keyCache, challengeCache, dnsLookupCache, canonicalDomainCache cache.SetGetKey,
keyDatabase database.KeyDB) *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))
sniBytes := []byte(sni)
if len(sni) < 1 {
return nil, errors.New("missing sni")
}
if info.SupportedProtos != nil {
for _, proto := range info.SupportedProtos {
if proto == tlsalpn01.ACMETLS1Protocol {
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 := ""
if bytes.HasSuffix(sniBytes, mainDomainSuffix) || bytes.Equal(sniBytes, mainDomainSuffix[1:]) {
// deliver default certificate for the main domain (*.codeberg.page)
sniBytes = mainDomainSuffix
sni = string(sniBytes)
} else {
var targetRepo, targetBranch string
targetOwner, targetRepo, targetBranch = getTargetFromDNS(sni, string(mainDomainSuffix), dnsLookupCache)
if targetOwner == "" {
// DNS not set up, return main certificate to redirect to the docs
sniBytes = mainDomainSuffix
sni = string(sniBytes)
} else {
_, _ = targetRepo, targetBranch
_, valid := checkCanonicalDomain(targetOwner, targetRepo, targetBranch, sni, string(mainDomainSuffix), giteaRoot, giteaApiToken, canonicalDomainCache)
if !valid {
sniBytes = mainDomainSuffix
sni = string(sniBytes)
}
}
}
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(sniBytes, mainDomainSuffix, dnsProvider, acmeUseRateLimits, keyDatabase); !ok {
// request a new certificate
if bytes.Equal(sniBytes, mainDomainSuffix) {
return nil, errors.New("won't request certificate for main domain, something really bad has happened")
}
tlsCertificate, err = obtainCert(acmeClient, []string{sni}, nil, targetOwner, dnsProvider, mainDomainSuffix, acmeUseRateLimits, keyDatabase)
if err != nil {
return nil, err
}
}
err = keyCache.Set(sni, &tlsCertificate, 15*time.Minute)
if err != nil {
panic(err)
}
return &tlsCertificate, nil
},
PreferServerCipherSuites: true,
NextProtos: []string{
"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 myAcmeAccount AcmeAccount
var myAcmeConfig *lego.Config
type AcmeAccount struct {
Email string
Registration *registration.Resource
Key crypto.PrivateKey `json:"-"`
KeyPEM string `json:"Key"`
}
func (u *AcmeAccount) GetEmail() string {
return u.Email
}
func (u AcmeAccount) GetRegistration() *registration.Resource {
return u.Registration
}
func (u *AcmeAccount) GetPrivateKey() crypto.PrivateKey {
return u.Key
}
var acmeClient, mainDomainAcmeClient *lego.Client
var 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)
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 []byte, dnsProvider string, acmeUseRateLimits bool, keyDatabase database.KeyDB) (tls.Certificate, bool) {
// parse certificate from database
res := &certificate.Resource{}
if !database.PogrebGet(keyDatabase, sni, res) {
return tls.Certificate{}, false
}
tlsCertificate, err := tls.X509KeyPair(res.Certificate, res.PrivateKey)
if err != nil {
panic(err)
}
// TODO: document & put into own function
if !bytes.Equal(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.After(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{string(sni)}, res, "", dnsProvider, mainDomainSuffix, acmeUseRateLimits, keyDatabase)
if err != nil {
log.Printf("Couldn't renew certificate for %s: %s", sni, err)
}
})()
}
}
return tlsCertificate, true
}
var obtainLocks = sync.Map{}
func obtainCert(acmeClient *lego.Client, domains []string, renew *certificate.Resource, user, dnsProvider string, mainDomainSuffix []byte, acmeUseRateLimits bool, keyDatabase database.KeyDB) (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([]byte(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!", string(mainDomainSuffix), keyDatabase), nil
}
// request actual cert
var res *certificate.Resource
var err error
if renew != nil && renew.CertURL != "" {
if acmeUseRateLimits {
acmeClientRequestLimit.Take()
}
log.Printf("Renewing certificate for %v", domains)
res, err = acmeClient.Certificate.Renew(*renew, true, false, "")
if err != nil {
log.Printf("Couldn't renew certificate for %v, trying to request a new one: %s", domains, err)
res = nil
}
}
if res == nil {
if user != "" {
if err := CheckUserLimit(user); err != nil {
return tls.Certificate{}, err
}
}
if acmeUseRateLimits {
acmeClientOrderLimit.Take()
acmeClientRequestLimit.Take()
}
log.Printf("Requesting new certificate for %v", domains)
res, err = acmeClient.Certificate.Obtain(certificate.ObtainRequest{
Domains: domains,
Bundle: true,
MustStaple: false,
})
}
if err != nil {
log.Printf("Couldn't obtain certificate for %v: %s", domains, err)
if renew != nil && renew.CertURL != "" {
tlsCertificate, err := tls.X509KeyPair(renew.Certificate, renew.PrivateKey)
if err == nil && tlsCertificate.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))
database.PogrebPut(keyDatabase, []byte(name), renew)
return tlsCertificate, nil
}
}
return mockCert(domains[0], err.Error(), string(mainDomainSuffix), keyDatabase), err
}
log.Printf("Obtained certificate for %v", domains)
database.PogrebPut(keyDatabase, []byte(name), res)
tlsCertificate, err := tls.X509KeyPair(res.Certificate, res.PrivateKey)
if err != nil {
return tls.Certificate{}, err
}
return tlsCertificate, nil
}
func mockCert(domain, msg, mainDomainSuffix string, keyDatabase database.KeyDB) tls.Certificate {
key, err := certcrypto.GeneratePrivateKey(certcrypto.RSA2048)
if err != nil {
panic(err)
}
template := x509.Certificate{
SerialNumber: big.NewInt(1),
Subject: pkix.Name{
CommonName: domain,
Organization: []string{"Codeberg Pages Error Certificate (couldn't obtain ACME certificate)"},
OrganizationalUnit: []string{
"Will not try again for 6 hours to avoid hitting rate limits for your domain.",
"Check https://docs.codeberg.org/codeberg-pages/troubleshooting/ for troubleshooting tips, and feel " +
"free to create an issue at https://codeberg.org/Codeberg/pages-server if you can't solve it.\n",
"Error message: " + msg,
},
},
// certificates younger than 7 days are renewed, so this enforces the cert to not be renewed for a 6 hours
NotAfter: time.Now().Add(time.Hour*24*7 + time.Hour*6),
NotBefore: time.Now(),
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
certBytes, err := x509.CreateCertificate(
rand.Reader,
&template,
&template,
&key.(*rsa.PrivateKey).PublicKey,
key,
)
if err != nil {
panic(err)
}
out := &bytes.Buffer{}
err = pem.Encode(out, &pem.Block{
Bytes: certBytes,
Type: "CERTIFICATE",
})
if err != nil {
panic(err)
}
outBytes := out.Bytes()
res := &certificate.Resource{
PrivateKey: certcrypto.PEMEncode(key),
Certificate: outBytes,
IssuerCertificate: outBytes,
Domain: domain,
}
databaseName := domain
if domain == "*"+mainDomainSuffix || domain == mainDomainSuffix[1:] {
databaseName = mainDomainSuffix
}
database.PogrebPut(keyDatabase, []byte(databaseName), res)
tlsCertificate, err := tls.X509KeyPair(res.Certificate, res.PrivateKey)
if err != nil {
panic(err)
}
return tlsCertificate
}
func SetupCertificates(mainDomainSuffix []byte, acmeAPI, acmeMail, acmeEabHmac, acmeEabKID, dnsProvider string, acmeUseRateLimits, acmeAcceptTerms, enableHTTPServer bool, challengeCache cache.SetGetKey, keyDatabase database.KeyDB) {
// getting main cert before ACME account so that we can panic here on database failure without hitting rate limits
mainCertBytes, err := keyDatabase.Get(mainDomainSuffix)
if err != nil {
// key database is not working
panic(err)
}
if account, err := ioutil.ReadFile("acme-account.json"); err == nil {
err = json.Unmarshal(account, &myAcmeAccount)
if err != nil {
panic(err)
}
myAcmeAccount.Key, err = certcrypto.ParsePEMPrivateKey([]byte(myAcmeAccount.KeyPEM))
if err != nil {
panic(err)
}
myAcmeConfig = lego.NewConfig(&myAcmeAccount)
myAcmeConfig.CADirURL = acmeAPI
myAcmeConfig.Certificate.KeyType = certcrypto.RSA2048
_, err := lego.NewClient(myAcmeConfig)
if err != nil {
log.Printf("[ERROR] Can't create ACME client, continuing with mock certs only: %s", err)
}
} else if os.IsNotExist(err) {
privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
panic(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.Printf("[ERROR] Can't create ACME client, continuing with mock certs only: %s", err)
} else {
// accept terms & log in to EAB
if acmeEabKID == "" || acmeEabHmac == "" {
reg, err := tempClient.Registration.Register(registration.RegisterOptions{TermsOfServiceAgreed: acmeAcceptTerms})
if err != nil {
log.Printf("[ERROR] Can't register ACME account, continuing with mock certs only: %s", err)
} else {
myAcmeAccount.Registration = reg
}
} else {
reg, err := tempClient.Registration.RegisterWithExternalAccountBinding(registration.RegisterEABOptions{
TermsOfServiceAgreed: acmeAcceptTerms,
Kid: acmeEabKID,
HmacEncoded: acmeEabHmac,
})
if err != nil {
log.Printf("[ERROR] Can't register ACME account, continuing with mock certs only: %s", err)
} else {
myAcmeAccount.Registration = reg
}
}
if myAcmeAccount.Registration != nil {
acmeAccountJson, err := json.Marshal(myAcmeAccount)
if err != nil {
log.Printf("[FAIL] Error during json.Marshal(myAcmeAccount), waiting for manual restart to avoid rate limits: %s", err)
select {}
}
err = ioutil.WriteFile("acme-account.json", acmeAccountJson, 0600)
if err != nil {
log.Printf("[FAIL] Error during ioutil.WriteFile(\"acme-account.json\"), waiting for manual restart to avoid rate limits: %s", err)
select {}
}
}
}
} else {
panic(err)
}
acmeClient, err = lego.NewClient(myAcmeConfig)
if err != nil {
log.Printf("[ERROR] Can't create ACME client, continuing with mock certs only: %s", err)
} else {
err = acmeClient.Challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{challengeCache})
if err != nil {
log.Printf("[ERROR] Can't create TLS-ALPN-01 provider: %s", err)
}
if enableHTTPServer {
err = acmeClient.Challenge.SetHTTP01Provider(AcmeHTTPChallengeProvider{challengeCache})
if err != nil {
log.Printf("[ERROR] Can't create HTTP-01 provider: %s", err)
}
}
}
mainDomainAcmeClient, err = lego.NewClient(myAcmeConfig)
if err != nil {
log.Printf("[ERROR] Can't create ACME client, continuing with mock certs only: %s", err)
} else {
if dnsProvider == "" {
// using mock server, don't use wildcard certs
err := mainDomainAcmeClient.Challenge.SetTLSALPN01Provider(AcmeTLSChallengeProvider{challengeCache})
if err != nil {
log.Printf("[ERROR] Can't create TLS-ALPN-01 provider: %s", err)
}
} else {
provider, err := dns.NewDNSChallengeProviderByName(dnsProvider)
if err != nil {
log.Printf("[ERROR] Can't create DNS Challenge provider: %s", err)
}
err = mainDomainAcmeClient.Challenge.SetDNS01Provider(provider)
if err != nil {
log.Printf("[ERROR] Can't create DNS-01 provider: %s", err)
}
}
}
if mainCertBytes == nil {
_, err = obtainCert(mainDomainAcmeClient, []string{"*" + string(mainDomainSuffix), string(mainDomainSuffix[1:])}, nil, "", dnsProvider, mainDomainSuffix, acmeUseRateLimits, keyDatabase)
if err != nil {
log.Printf("[ERROR] Couldn't renew main domain certificate, continuing with mock certs only: %s", err)
}
}
go (func() {
for {
err := keyDatabase.Sync()
if err != nil {
log.Printf("[ERROR] Syncing key database failed: %s", err)
}
time.Sleep(5 * time.Minute)
// TODO: graceful exit
}
})()
go (func() {
for {
// clean up expired certs
now := time.Now()
expiredCertCount := 0
keyDatabaseIterator := keyDatabase.Items()
key, resBytes, err := keyDatabaseIterator.Next()
for err == nil {
if !bytes.Equal(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.After(now) {
err := keyDatabase.Delete(key)
if err != nil {
log.Printf("[ERROR] Deleting expired certificate for %s failed: %s", string(key), err)
} else {
expiredCertCount++
}
}
}
key, resBytes, err = keyDatabaseIterator.Next()
}
log.Printf("[INFO] Removed %d expired certificates from the database", expiredCertCount)
// compact the database
result, err := keyDatabase.Compact()
if err != nil {
log.Printf("[ERROR] Compacting key database failed: %s", err)
} else {
log.Printf("[INFO] Compacted key database (%+v)", result)
}
// update main cert
res := &certificate.Resource{}
if !database.PogrebGet(keyDatabase, mainDomainSuffix, res) {
log.Printf("[ERROR] Couldn't renew certificate for main domain: %s", "expected main domain cert to exist, but it's missing - seems like the database is corrupted")
} else {
tlsCertificates, err := certcrypto.ParsePEMBundle(res.Certificate)
// renew main certificate 30 days before it expires
if !tlsCertificates[0].NotAfter.After(time.Now().Add(-30 * 24 * time.Hour)) {
go (func() {
_, err = obtainCert(mainDomainAcmeClient, []string{"*" + string(mainDomainSuffix), string(mainDomainSuffix[1:])}, res, "", dnsProvider, mainDomainSuffix, acmeUseRateLimits, keyDatabase)
if err != nil {
log.Printf("[ERROR] Couldn't renew certificate for main domain: %s", err)
}
})()
}
}
time.Sleep(12 * time.Hour)
}
})()
}