1
Fork 0
mirror of https://github.com/caddyserver/caddy.git synced 2024-12-16 21:56:40 -05:00
caddy/modules/caddytls/connpolicy.go

237 lines
7.4 KiB
Go

package caddytls
import (
"crypto/tls"
"crypto/x509"
"encoding/json"
"fmt"
"math/big"
"strings"
"bitbucket.org/lightcodelabs/caddy2"
"github.com/go-acme/lego/challenge/tlsalpn01"
"github.com/mholt/certmagic"
)
// ConnectionPolicies is an ordered group of connection policies;
// the first matching policy will be used to configure TLS
// connections at handshake-time.
type ConnectionPolicies []*ConnectionPolicy
// TLSConfig converts the group of policies to a standard-lib-compatible
// TLS configuration which selects the first matching policy based on
// the ClientHello.
func (cp ConnectionPolicies) TLSConfig(ctx caddy2.Context) (*tls.Config, error) {
// connection policy matchers
for i, pol := range cp {
for modName, rawMsg := range pol.MatchersRaw {
val, err := ctx.LoadModule("tls.handshake_match."+modName, rawMsg)
if err != nil {
return nil, fmt.Errorf("loading handshake matcher module '%s': %s", modName, err)
}
cp[i].matchers = append(cp[i].matchers, val.(ConnectionMatcher))
}
cp[i].MatchersRaw = nil // allow GC to deallocate - TODO: Does this help?
}
// pre-build standard TLS configs so we don't have to at handshake-time
for i := range cp {
err := cp[i].buildStandardTLSConfig(ctx)
if err != nil {
return nil, fmt.Errorf("connection policy %d: building standard TLS config: %s", i, err)
}
}
// using ServerName to match policies is extremely common, especially in configs
// with lots and lots of different policies; we can fast-track those by indexing
// them by SNI, so we don't have to iterate potentially thousands of policies
indexedBySNI := make(map[string]ConnectionPolicies)
if len(cp) > 30 {
for _, p := range cp {
for _, m := range p.matchers {
if sni, ok := m.(MatchServerName); ok {
for _, sniName := range sni {
indexedBySNI[sniName] = append(indexedBySNI[sniName], p)
}
}
}
}
}
return &tls.Config{
GetConfigForClient: func(hello *tls.ClientHelloInfo) (*tls.Config, error) {
// filter policies by SNI first, if possible, to speed things up
// when there may be lots of policies
possiblePolicies := cp
if indexedPolicies, ok := indexedBySNI[hello.ServerName]; ok {
possiblePolicies = indexedPolicies
}
policyLoop:
for _, pol := range possiblePolicies {
for _, matcher := range pol.matchers {
if !matcher.Match(hello) {
continue policyLoop
}
}
return pol.stdTLSConfig, nil
}
return nil, fmt.Errorf("no server TLS configuration available for ClientHello: %+v", hello)
},
}, nil
}
// ConnectionPolicy specifies the logic for handling a TLS handshake.
type ConnectionPolicy struct {
MatchersRaw map[string]json.RawMessage `json:"match,omitempty"`
CipherSuites []string `json:"cipher_suites,omitempty"`
Curves []string `json:"curves,omitempty"`
ALPN []string `json:"alpn,omitempty"`
ProtocolMin string `json:"protocol_min,omitempty"`
ProtocolMax string `json:"protocol_max,omitempty"`
CertSelection *CertSelectionPolicy `json:"certificate_selection,omitempty"`
// TODO: Client auth
// TODO: see if starlark could be useful here - enterprise only
StarlarkHandshake string `json:"starlark_handshake,omitempty"`
matchers []ConnectionMatcher
stdTLSConfig *tls.Config
}
func (p *ConnectionPolicy) buildStandardTLSConfig(ctx caddy2.Context) error {
tlsAppIface, err := ctx.App("tls")
if err != nil {
return fmt.Errorf("getting tls app: %v", err)
}
tlsApp := tlsAppIface.(*TLS)
cfg := &tls.Config{
NextProtos: p.ALPN,
PreferServerCipherSuites: true,
GetCertificate: func(hello *tls.ClientHelloInfo) (*tls.Certificate, error) {
cfgTpl, err := tlsApp.getConfigForName(hello.ServerName)
if err != nil {
return nil, fmt.Errorf("getting config for name %s: %v", hello.ServerName, err)
}
newCfg := certmagic.New(tlsApp.certCache, cfgTpl)
if p.CertSelection != nil {
newCfg.CertSelector = makeCertSelector(p)
}
return newCfg.GetCertificate(hello)
},
MinVersion: tls.VersionTLS12,
MaxVersion: tls.VersionTLS13,
// TODO: Session ticket key rotation (use Storage)
}
// add all the cipher suites in order, without duplicates
cipherSuitesAdded := make(map[uint16]struct{})
for _, csName := range p.CipherSuites {
csID := supportedCipherSuites[csName]
if _, ok := cipherSuitesAdded[csID]; !ok {
cipherSuitesAdded[csID] = struct{}{}
cfg.CipherSuites = append(cfg.CipherSuites, csID)
}
}
// add all the curve preferences in order, without duplicates
curvesAdded := make(map[tls.CurveID]struct{})
for _, curveName := range p.Curves {
curveID := supportedCurves[curveName]
if _, ok := curvesAdded[curveID]; !ok {
curvesAdded[curveID] = struct{}{}
cfg.CurvePreferences = append(cfg.CurvePreferences, curveID)
}
}
// ensure ALPN includes the ACME TLS-ALPN protocol
var alpnFound bool
for _, a := range p.ALPN {
if a == tlsalpn01.ACMETLS1Protocol {
alpnFound = true
break
}
}
if !alpnFound {
cfg.NextProtos = append(cfg.NextProtos, tlsalpn01.ACMETLS1Protocol)
}
// min and max protocol versions
if p.ProtocolMin != "" {
cfg.MinVersion = supportedProtocols[p.ProtocolMin]
}
if p.ProtocolMax != "" {
cfg.MaxVersion = supportedProtocols[p.ProtocolMax]
}
if p.ProtocolMin > p.ProtocolMax {
return fmt.Errorf("protocol min (%x) cannot be greater than protocol max (%x)", p.ProtocolMin, p.ProtocolMax)
}
// TODO: client auth, and other fields
p.stdTLSConfig = cfg
return nil
}
// CertSelectionPolicy represents a policy for selecting the certificate
// used to complete a handshake when there may be multiple options. All
// fields specified must match the candidate certificate for it to be chosen.
// This was needed to solve https://github.com/mholt/caddy/issues/2588.
type CertSelectionPolicy struct {
SerialNumber *big.Int `json:"serial_number,omitempty"`
SubjectOrganization string `json:"subject.organization,omitempty"`
PublicKeyAlgorithm pkAlgorithm `json:"public_key_algorithm,omitempty"`
}
func makeCertSelector(p *ConnectionPolicy) func(*tls.ClientHelloInfo, []certmagic.Certificate) (certmagic.Certificate, error) {
return func(hello *tls.ClientHelloInfo, choices []certmagic.Certificate) (certmagic.Certificate, error) {
for _, cert := range choices {
var matchOrg bool
if p.CertSelection.SubjectOrganization != "" {
for _, org := range cert.Subject.Organization {
if p.CertSelection.SubjectOrganization == org {
matchOrg = true
break
}
}
}
if !matchOrg {
continue
}
if p.CertSelection.PublicKeyAlgorithm != pkAlgorithm(x509.UnknownPublicKeyAlgorithm) &&
pkAlgorithm(cert.PublicKeyAlgorithm) != p.CertSelection.PublicKeyAlgorithm {
continue
}
if p.CertSelection.SerialNumber != nil &&
cert.SerialNumber.Cmp(p.CertSelection.SerialNumber) != 0 {
continue
}
return cert, nil
}
return certmagic.Certificate{}, fmt.Errorf("no certificates matched custom selection policy")
}
}
type pkAlgorithm x509.PublicKeyAlgorithm
// UnmarshalJSON satisfies json.Unmarshaler.
func (a *pkAlgorithm) UnmarshalJSON(b []byte) error {
algoStr := strings.ToLower(strings.Trim(string(b), `"`))
algo, ok := publicKeyAlgorithms[algoStr]
if !ok {
return fmt.Errorf("unrecognized public key algorithm: %s (expected one of %v)",
algoStr, publicKeyAlgorithms)
}
a = &algo
return nil
}
// ConnectionMatcher is a type which matches TLS handshakes.
type ConnectionMatcher interface {
Match(*tls.ClientHelloInfo) bool
}