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caddytls: Refactor certificate selection policies (close #1575)

Certificate selection used to be a module, but this seems unnecessary,
especially since the built-in CustomSelectionPolicy allows quite complex
selection logic on a number of fields in certs. If we need to extend
that logic, we can, but I don't think there are SO many possibilities
that we need modules.

This update also allows certificate selection to choose between multiple
matching certs based on client compatibility and makes a number of other
improvements in the default cert selection logic, both here and in the
latest CertMagic.

The hardest part of this was the conn policy consolidation logic
(Caddyfile only, of course). We have to merge connection policies that
we can easily combine, because if two certs are manually loaded in a
Caddyfile site block, that produces two connection policies, and each
cert is tagged with a different tag, meaning only the first would ever
be selected. So given the same matchers, we can merge the two, but this
required improving the Tag selection logic to support multiple tags to
choose from, hence "tags" changed to "any_tag" or "all_tags" (but we
use any_tag in our Caddyfile logic).

Combining conn policies with conflicting settings is impossible, so
that should return an error if two policies with the exact same matchers
have non-empty settings that are not the same (the one exception being
any_tag which we can merge because the logic for them is to OR them).

It was a bit complicated. It seems to work in numerous tests I've
conducted, but we'll see how it pans out in the release candidates.
master
Matthew Holt 5 years ago
parent
commit
6ca5828221
No known key found for this signature in database GPG Key ID: 2A349DD577D586A5
  1. 5
      caddyconfig/caddyfile/adapter.go
  2. 10
      caddyconfig/httpcaddyfile/builtins.go
  3. 107
      caddyconfig/httpcaddyfile/httptype.go
  4. 9
      caddytest/integration/sni_test.go
  5. 2
      go.mod
  6. 4
      go.sum
  7. 101
      modules/caddytls/certselection.go
  8. 19
      modules/caddytls/connpolicy.go

5
caddyconfig/caddyfile/adapter.go

@ -68,6 +68,11 @@ func (a Adapter) Adapt(body []byte, options map[string]interface{}) ([]byte, []c
// into JSON. Caddyfile-unmarshaled values
// will not be used directly; they will be
// encoded as JSON and then used from that.
// Implementations must be able to support
// multiple segments (instances of their
// directive or batch of tokens); typically
// this means wrapping all token logic in
// a loop: `for d.Next() { ... }`.
type Unmarshaler interface {
UnmarshalCaddyfile(d *Dispenser) error
}

10
caddyconfig/httpcaddyfile/builtins.go

@ -71,6 +71,7 @@ func parseTLS(h Helper) ([]ConfigValue, error) {
cp := new(caddytls.ConnectionPolicy)
var fileLoader caddytls.FileLoader
var folderLoader caddytls.FolderLoader
var certSelector caddytls.CustomCertSelectionPolicy
var acmeIssuer *caddytls.ACMEIssuer
var internalIssuer *caddytls.InternalIssuer
var onDemand bool
@ -135,8 +136,8 @@ func parseTLS(h Helper) ([]ConfigValue, error) {
// remember this for next time we see this cert file
tlsCertTags[certFilename] = tag
}
certSelector := caddytls.CustomCertSelectionPolicy{Tag: tag}
cp.CertSelection = caddyconfig.JSONModuleObject(certSelector, "policy", "custom", h.warnings)
certSelector.AnyTag = append(certSelector.AnyTag, tag)
default:
return nil, h.ArgErr()
}
@ -297,6 +298,11 @@ func parseTLS(h Helper) ([]ConfigValue, error) {
})
}
// custom certificate selection
if len(certSelector.AnyTag) > 0 {
cp.CertSelection = &certSelector
}
// connection policy -- always add one, to ensure that TLS
// is enabled, because this directive was used (this is
// needed, for instance, when a site block has a key of

107
caddyconfig/httpcaddyfile/httptype.go

@ -527,7 +527,11 @@ func (st *ServerType) serversFromPairings(
}
// tidy things up a bit
srv.TLSConnPolicies = consolidateConnPolicies(srv.TLSConnPolicies)
var err error
srv.TLSConnPolicies, err = consolidateConnPolicies(srv.TLSConnPolicies)
if err != nil {
return nil, fmt.Errorf("consolidating TLS connection policies for server %d: %v", i, err)
}
srv.Routes = consolidateRoutes(srv.Routes)
servers[fmt.Sprintf("srv%d", i)] = srv
@ -538,7 +542,7 @@ func (st *ServerType) serversFromPairings(
// consolidateConnPolicies combines TLS connection policies that are the same,
// for a cleaner overall output.
func consolidateConnPolicies(cps caddytls.ConnectionPolicies) caddytls.ConnectionPolicies {
func consolidateConnPolicies(cps caddytls.ConnectionPolicies) (caddytls.ConnectionPolicies, error) {
for i := 0; i < len(cps); i++ {
for j := 0; j < len(cps); j++ {
if j == i {
@ -551,9 +555,106 @@ func consolidateConnPolicies(cps caddytls.ConnectionPolicies) caddytls.Connectio
i--
break
}
// if they have the same matcher, try to reconcile each field: either they must
// be identical, or we have to be able to combine them safely
if reflect.DeepEqual(cps[i].MatchersRaw, cps[j].MatchersRaw) {
if len(cps[i].ALPN) > 0 &&
len(cps[j].ALPN) > 0 &&
!reflect.DeepEqual(cps[i].ALPN, cps[j].ALPN) {
return nil, fmt.Errorf("two policies with same match criteria have conflicting ALPN: %v vs. %v",
cps[i].ALPN, cps[j].ALPN)
}
if len(cps[i].CipherSuites) > 0 &&
len(cps[j].CipherSuites) > 0 &&
!reflect.DeepEqual(cps[i].CipherSuites, cps[j].CipherSuites) {
return nil, fmt.Errorf("two policies with same match criteria have conflicting cipher suites: %v vs. %v",
cps[i].CipherSuites, cps[j].CipherSuites)
}
if cps[i].ClientAuthentication == nil &&
cps[j].ClientAuthentication != nil &&
!reflect.DeepEqual(cps[i].ClientAuthentication, cps[j].ClientAuthentication) {
return nil, fmt.Errorf("two policies with same match criteria have conflicting client auth configuration: %+v vs. %+v",
cps[i].ClientAuthentication, cps[j].ClientAuthentication)
}
if len(cps[i].Curves) > 0 &&
len(cps[j].Curves) > 0 &&
!reflect.DeepEqual(cps[i].Curves, cps[j].Curves) {
return nil, fmt.Errorf("two policies with same match criteria have conflicting curves: %v vs. %v",
cps[i].Curves, cps[j].Curves)
}
if cps[i].DefaultSNI != "" &&
cps[j].DefaultSNI != "" &&
cps[i].DefaultSNI != cps[j].DefaultSNI {
return nil, fmt.Errorf("two policies with same match criteria have conflicting default SNI: %s vs. %s",
cps[i].DefaultSNI, cps[j].DefaultSNI)
}
if cps[i].ProtocolMin != "" &&
cps[j].ProtocolMin != "" &&
cps[i].ProtocolMin != cps[j].ProtocolMin {
return nil, fmt.Errorf("two policies with same match criteria have conflicting min protocol: %s vs. %s",
cps[i].ProtocolMin, cps[j].ProtocolMin)
}
if cps[i].ProtocolMax != "" &&
cps[j].ProtocolMax != "" &&
cps[i].ProtocolMax != cps[j].ProtocolMax {
return nil, fmt.Errorf("two policies with same match criteria have conflicting max protocol: %s vs. %s",
cps[i].ProtocolMax, cps[j].ProtocolMax)
}
if cps[i].CertSelection != nil && cps[j].CertSelection != nil {
// merging fields other than AnyTag is not implemented
if !reflect.DeepEqual(cps[i].CertSelection.SerialNumber, cps[j].CertSelection.SerialNumber) ||
!reflect.DeepEqual(cps[i].CertSelection.SubjectOrganization, cps[j].CertSelection.SubjectOrganization) ||
cps[i].CertSelection.PublicKeyAlgorithm != cps[j].CertSelection.PublicKeyAlgorithm ||
!reflect.DeepEqual(cps[i].CertSelection.AllTags, cps[j].CertSelection.AllTags) {
return nil, fmt.Errorf("two policies with same match criteria have conflicting cert selections: %+v vs. %+v",
cps[i].CertSelection, cps[j].CertSelection)
}
}
// by now we've decided that we can merge the two -- we'll keep i and drop j
if len(cps[i].ALPN) == 0 && len(cps[j].ALPN) > 0 {
cps[i].ALPN = cps[j].ALPN
}
if len(cps[i].CipherSuites) == 0 && len(cps[j].CipherSuites) > 0 {
cps[i].CipherSuites = cps[j].CipherSuites
}
if cps[i].ClientAuthentication == nil && cps[j].ClientAuthentication != nil {
cps[i].ClientAuthentication = cps[j].ClientAuthentication
}
if len(cps[i].Curves) == 0 && len(cps[j].Curves) > 0 {
cps[i].Curves = cps[j].Curves
}
if cps[i].DefaultSNI == "" && cps[j].DefaultSNI != "" {
cps[i].DefaultSNI = cps[j].DefaultSNI
}
if cps[i].ProtocolMin == "" && cps[j].ProtocolMin != "" {
cps[i].ProtocolMin = cps[j].ProtocolMin
}
if cps[i].ProtocolMax == "" && cps[j].ProtocolMax != "" {
cps[i].ProtocolMax = cps[j].ProtocolMax
}
if cps[i].CertSelection == nil && cps[j].CertSelection != nil {
// if j is the only one with a policy, move it over to i
cps[i].CertSelection = cps[j].CertSelection
} else if cps[i].CertSelection != nil && cps[j].CertSelection != nil {
// if both have one, then combine AnyTag
for _, tag := range cps[j].CertSelection.AnyTag {
if !sliceContains(cps[i].CertSelection.AnyTag, tag) {
cps[i].CertSelection.AnyTag = append(cps[i].CertSelection.AnyTag, tag)
}
}
}
cps = append(cps[:j], cps[j+1:]...)
i--
break
}
}
}
return cps
return cps, nil
}
// appendSubrouteToRouteList appends the routes in subroute

9
caddytest/integration/sni_test.go

@ -57,8 +57,7 @@ func TestDefaultSNI(t *testing.T) {
"tls_connection_policies": [
{
"certificate_selection": {
"policy": "custom",
"tag": "cert0"
"any_tag": ["cert0"]
},
"match": {
"sni": [
@ -155,8 +154,7 @@ func TestDefaultSNIWithNamedHostAndExplicitIP(t *testing.T) {
"tls_connection_policies": [
{
"certificate_selection": {
"policy": "custom",
"tag": "cert0"
"any_tag": ["cert0"]
},
"default_sni": "a.caddy.localhost",
"match": {
@ -238,8 +236,7 @@ func TestDefaultSNIWithPortMappingOnly(t *testing.T) {
"tls_connection_policies": [
{
"certificate_selection": {
"policy": "custom",
"tag": "cert0"
"any_tag": ["cert0"]
},
"default_sni": "a.caddy.localhost"
}

2
go.mod

@ -5,7 +5,7 @@ go 1.14
require (
github.com/Masterminds/sprig/v3 v3.0.2
github.com/alecthomas/chroma v0.7.2-0.20200305040604-4f3623dce67a
github.com/caddyserver/certmagic v0.10.6
github.com/caddyserver/certmagic v0.10.7
github.com/dustin/go-humanize v1.0.1-0.20200219035652-afde56e7acac
github.com/go-acme/lego/v3 v3.5.0
github.com/google/cel-go v0.4.1

4
go.sum

@ -120,8 +120,8 @@ github.com/bombsimon/wsl/v2 v2.0.0/go.mod h1:mf25kr/SqFEPhhcxW1+7pxzGlW+hIl/hYTK
github.com/boombuler/barcode v1.0.0/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
github.com/bradfitz/go-smtpd v0.0.0-20170404230938-deb6d6237625/go.mod h1:HYsPBTaaSFSlLx/70C2HPIMNZpVV8+vt/A+FMnYP11g=
github.com/buger/jsonparser v0.0.0-20181115193947-bf1c66bbce23/go.mod h1:bbYlZJ7hK1yFx9hf58LP0zeX7UjIGs20ufpu3evjr+s=
github.com/caddyserver/certmagic v0.10.6 h1:sCya6FmfaN74oZE46kqfaFOVoROD/mF36rTQfjN7TZc=
github.com/caddyserver/certmagic v0.10.6/go.mod h1:Y8jcUBctgk/IhpAzlHKfimZNyXCkfGgRTC0orl8gROQ=
github.com/caddyserver/certmagic v0.10.7 h1:OwT4Delj91ee7vumu+CnFJdWLsYBYj6kJ2PwsoqI7LA=
github.com/caddyserver/certmagic v0.10.7/go.mod h1:Y8jcUBctgk/IhpAzlHKfimZNyXCkfGgRTC0orl8gROQ=
github.com/cenkalti/backoff/v4 v4.0.0 h1:6VeaLF9aI+MAUQ95106HwWzYZgJJpZ4stumjj6RFYAU=
github.com/cenkalti/backoff/v4 v4.0.0/go.mod h1:eEew/i+1Q6OrCDZh3WiXYv3+nJwBASZ8Bog/87DQnVg=
github.com/census-instrumentation/opencensus-proto v0.2.0/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=

101
modules/caddytls/certselection.go

@ -20,65 +20,104 @@ import (
"fmt"
"math/big"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/certmagic"
)
func init() {
caddy.RegisterModule(CustomCertSelectionPolicy{})
}
// CustomCertSelectionPolicy 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/caddyserver/caddy/issues/2588.
type CustomCertSelectionPolicy struct {
SerialNumber *big.Int `json:"serial_number,omitempty"`
SubjectOrganization string `json:"subject_organization,omitempty"`
PublicKeyAlgorithm PublicKeyAlgorithm `json:"public_key_algorithm,omitempty"`
Tag string `json:"tag,omitempty"`
}
// The certificate must have one of these serial numbers.
SerialNumber []*big.Int `json:"serial_number,omitempty"`
// CaddyModule returns the Caddy module information.
func (CustomCertSelectionPolicy) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "tls.certificate_selection.custom",
New: func() caddy.Module { return new(CustomCertSelectionPolicy) },
}
// The certificate must have one of these organization names.
SubjectOrganization []string `json:"subject_organization,omitempty"`
// The certificate must use this public key algorithm.
PublicKeyAlgorithm PublicKeyAlgorithm `json:"public_key_algorithm,omitempty"`
// The certificate must have at least one of the tags in the list.
AnyTag []string `json:"any_tag,omitempty"`
// The certificate must have all of the tags in the list.
AllTags []string `json:"all_tags,omitempty"`
}
// SelectCertificate implements certmagic.CertificateSelector.
func (p CustomCertSelectionPolicy) SelectCertificate(_ *tls.ClientHelloInfo, choices []certmagic.Certificate) (certmagic.Certificate, error) {
// SelectCertificate implements certmagic.CertificateSelector. It
// only chooses a certificate that at least meets the criteria in
// p. It then chooses the first non-expired certificate that is
// compatible with the client. If none are valid, it chooses the
// first viable candidate anyway.
func (p CustomCertSelectionPolicy) SelectCertificate(hello *tls.ClientHelloInfo, choices []certmagic.Certificate) (certmagic.Certificate, error) {
viable := make([]certmagic.Certificate, 0, len(choices))
nextChoice:
for _, cert := range choices {
if p.SerialNumber != nil && cert.SerialNumber.Cmp(p.SerialNumber) != 0 {
continue
if len(p.SerialNumber) > 0 {
var found bool
for _, sn := range p.SerialNumber {
if cert.Leaf.SerialNumber.Cmp(sn) == 0 {
found = true
break
}
}
if !found {
continue
}
}
if len(p.SubjectOrganization) > 0 {
var found bool
for _, subjOrg := range p.SubjectOrganization {
for _, org := range cert.Leaf.Subject.Organization {
if subjOrg == org {
found = true
break
}
}
}
if !found {
continue
}
}
if p.PublicKeyAlgorithm != PublicKeyAlgorithm(x509.UnknownPublicKeyAlgorithm) &&
PublicKeyAlgorithm(cert.PublicKeyAlgorithm) != p.PublicKeyAlgorithm {
PublicKeyAlgorithm(cert.Leaf.PublicKeyAlgorithm) != p.PublicKeyAlgorithm {
continue
}
if p.SubjectOrganization != "" {
var matchOrg bool
for _, org := range cert.Subject.Organization {
if p.SubjectOrganization == org {
matchOrg = true
if len(p.AnyTag) > 0 {
var found bool
for _, tag := range p.AnyTag {
if cert.HasTag(tag) {
found = true
break
}
}
if !matchOrg {
if !found {
continue
}
}
if p.Tag != "" && !cert.HasTag(p.Tag) {
continue
if len(p.AllTags) > 0 {
for _, tag := range p.AllTags {
if !cert.HasTag(tag) {
continue nextChoice
}
}
}
return cert, nil
// this certificate at least meets the policy's requirements,
// but we still have to check expiration and compatibility
viable = append(viable, cert)
}
return certmagic.Certificate{}, fmt.Errorf("no certificates matched custom selection policy")
if len(viable) == 0 {
return certmagic.Certificate{}, fmt.Errorf("no certificates matched custom selection policy")
}
return certmagic.DefaultCertificateSelector(hello, viable)
}
// Interface guard

19
modules/caddytls/connpolicy.go

@ -18,12 +18,10 @@ import (
"crypto/tls"
"crypto/x509"
"encoding/base64"
"encoding/json"
"fmt"
"strings"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/certmagic"
"github.com/go-acme/lego/v3/challenge/tlsalpn01"
)
@ -46,15 +44,6 @@ func (cp ConnectionPolicies) Provision(ctx caddy.Context) error {
cp[i].matchers = append(cp[i].matchers, modIface.(ConnectionMatcher))
}
// certificate selector
if pol.CertSelection != nil {
val, err := ctx.LoadModule(pol, "CertSelection")
if err != nil {
return fmt.Errorf("loading certificate selection module: %s", err)
}
cp[i].certSelector = val.(certmagic.CertificateSelector)
}
// enable HTTP/2 by default
if len(pol.ALPN) == 0 {
pol.ALPN = append(pol.ALPN, defaultALPN...)
@ -123,7 +112,7 @@ type ConnectionPolicy struct {
// How to choose a certificate if more than one matched
// the given ServerName (SNI) value.
CertSelection json.RawMessage `json:"certificate_selection,omitempty" caddy:"namespace=tls.certificate_selection inline_key=policy"`
CertSelection *CustomCertSelectionPolicy `json:"certificate_selection,omitempty"`
// The list of cipher suites to support. Caddy's
// defaults are modern and secure.
@ -151,8 +140,6 @@ type ConnectionPolicy struct {
DefaultSNI string `json:"default_sni,omitempty"`
matchers []ConnectionMatcher
certSelector certmagic.CertificateSelector
stdTLSConfig *tls.Config
}
@ -184,9 +171,7 @@ func (p *ConnectionPolicy) buildStandardTLSConfig(ctx caddy.Context) error {
// more at handshake-time, but I don't know how to practically pre-build
// a certmagic config for each combination of conn policy + automation policy...
cfg := *tlsApp.getConfigForName(hello.ServerName)
if p.certSelector != nil {
cfg.CertSelection = p.certSelector
}
cfg.CertSelection = p.CertSelection
cfg.DefaultServerName = p.DefaultSNI
return cfg.GetCertificate(hello)
},

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