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path_login.go
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path_login.go
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package cert
import (
"bytes"
"context"
"crypto/tls"
"crypto/x509"
"encoding/asn1"
"encoding/base64"
"encoding/pem"
"errors"
"fmt"
"strings"
"github.com/hashicorp/vault/helper/certutil"
"github.com/hashicorp/vault/helper/policyutil"
"github.com/hashicorp/vault/logical"
"github.com/hashicorp/vault/logical/framework"
"github.com/hashicorp/vault/helper/cidrutil"
"github.com/ryanuber/go-glob"
)
// ParsedCert is a certificate that has been configured as trusted
type ParsedCert struct {
Entry *CertEntry
Certificates []*x509.Certificate
}
func pathLogin(b *backend) *framework.Path {
return &framework.Path{
Pattern: "login",
Fields: map[string]*framework.FieldSchema{
"name": &framework.FieldSchema{
Type: framework.TypeString,
Description: "The name of the certificate role to authenticate against.",
},
},
Callbacks: map[logical.Operation]framework.OperationFunc{
logical.UpdateOperation: b.pathLogin,
logical.AliasLookaheadOperation: b.pathLoginAliasLookahead,
},
}
}
func (b *backend) pathLoginAliasLookahead(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
clientCerts := req.Connection.ConnState.PeerCertificates
if len(clientCerts) == 0 {
return nil, fmt.Errorf("no client certificate found")
}
return &logical.Response{
Auth: &logical.Auth{
Alias: &logical.Alias{
Name: clientCerts[0].Subject.CommonName,
},
},
}, nil
}
func (b *backend) pathLogin(ctx context.Context, req *logical.Request, data *framework.FieldData) (*logical.Response, error) {
var matched *ParsedCert
if verifyResp, resp, err := b.verifyCredentials(ctx, req, data); err != nil {
return nil, err
} else if resp != nil {
return resp, nil
} else {
matched = verifyResp
}
if matched == nil {
return nil, nil
}
if err := b.checkCIDR(matched.Entry, req); err != nil {
return nil, err
}
clientCerts := req.Connection.ConnState.PeerCertificates
if len(clientCerts) == 0 {
return logical.ErrorResponse("no client certificate found"), nil
}
skid := base64.StdEncoding.EncodeToString(clientCerts[0].SubjectKeyId)
akid := base64.StdEncoding.EncodeToString(clientCerts[0].AuthorityKeyId)
resp := &logical.Response{
Auth: &logical.Auth{
Period: matched.Entry.Period,
InternalData: map[string]interface{}{
"subject_key_id": skid,
"authority_key_id": akid,
},
Policies: matched.Entry.Policies,
DisplayName: matched.Entry.DisplayName,
Metadata: map[string]string{
"cert_name": matched.Entry.Name,
"common_name": clientCerts[0].Subject.CommonName,
"serial_number": clientCerts[0].SerialNumber.String(),
"subject_key_id": certutil.GetHexFormatted(clientCerts[0].SubjectKeyId, ":"),
"authority_key_id": certutil.GetHexFormatted(clientCerts[0].AuthorityKeyId, ":"),
},
LeaseOptions: logical.LeaseOptions{
Renewable: true,
TTL: matched.Entry.TTL,
MaxTTL: matched.Entry.MaxTTL,
},
Alias: &logical.Alias{
Name: clientCerts[0].Subject.CommonName,
},
BoundCIDRs: matched.Entry.BoundCIDRs,
},
}
// Generate a response
return resp, nil
}
func (b *backend) pathLoginRenew(ctx context.Context, req *logical.Request, d *framework.FieldData) (*logical.Response, error) {
config, err := b.Config(ctx, req.Storage)
if err != nil {
return nil, err
}
if !config.DisableBinding {
var matched *ParsedCert
if verifyResp, resp, err := b.verifyCredentials(ctx, req, d); err != nil {
return nil, err
} else if resp != nil {
return resp, nil
} else {
matched = verifyResp
}
if matched == nil {
return nil, nil
}
clientCerts := req.Connection.ConnState.PeerCertificates
if len(clientCerts) == 0 {
return logical.ErrorResponse("no client certificate found"), nil
}
skid := base64.StdEncoding.EncodeToString(clientCerts[0].SubjectKeyId)
akid := base64.StdEncoding.EncodeToString(clientCerts[0].AuthorityKeyId)
// Certificate should not only match a registered certificate policy.
// Also, the identity of the certificate presented should match the identity of the certificate used during login
if req.Auth.InternalData["subject_key_id"] != skid && req.Auth.InternalData["authority_key_id"] != akid {
return nil, fmt.Errorf("client identity during renewal not matching client identity used during login")
}
}
// Get the cert and use its TTL
cert, err := b.Cert(ctx, req.Storage, req.Auth.Metadata["cert_name"])
if err != nil {
return nil, err
}
if cert == nil {
// User no longer exists, do not renew
return nil, nil
}
if !policyutil.EquivalentPolicies(cert.Policies, req.Auth.TokenPolicies) {
return nil, fmt.Errorf("policies have changed, not renewing")
}
resp := &logical.Response{Auth: req.Auth}
resp.Auth.TTL = cert.TTL
resp.Auth.MaxTTL = cert.MaxTTL
resp.Auth.Period = cert.Period
return resp, nil
}
func (b *backend) verifyCredentials(ctx context.Context, req *logical.Request, d *framework.FieldData) (*ParsedCert, *logical.Response, error) {
// Get the connection state
if req.Connection == nil || req.Connection.ConnState == nil {
return nil, logical.ErrorResponse("tls connection required"), nil
}
connState := req.Connection.ConnState
if connState.PeerCertificates == nil || len(connState.PeerCertificates) == 0 {
return nil, logical.ErrorResponse("client certificate must be supplied"), nil
}
clientCert := connState.PeerCertificates[0]
// Allow constraining the login request to a single CertEntry
var certName string
if req.Auth != nil { // It's a renewal, use the saved certName
certName = req.Auth.Metadata["cert_name"]
} else {
certName = d.Get("name").(string)
}
// Load the trusted certificates
roots, trusted, trustedNonCAs := b.loadTrustedCerts(ctx, req.Storage, certName)
// Get the list of full chains matching the connection and validates the
// certificate itself
trustedChains, err := validateConnState(roots, connState)
if err != nil {
return nil, nil, err
}
// If trustedNonCAs is not empty it means that client had registered a non-CA cert
// with the backend.
if len(trustedNonCAs) != 0 {
for _, trustedNonCA := range trustedNonCAs {
tCert := trustedNonCA.Certificates[0]
// Check for client cert being explicitly listed in the config (and matching other constraints)
if tCert.SerialNumber.Cmp(clientCert.SerialNumber) == 0 &&
bytes.Equal(tCert.AuthorityKeyId, clientCert.AuthorityKeyId) &&
b.matchesConstraints(clientCert, trustedNonCA.Certificates, trustedNonCA) {
return trustedNonCA, nil, nil
}
}
}
// If no trusted chain was found, client is not authenticated
// This check happens after checking for a matching configured non-CA certs
if len(trustedChains) == 0 {
return nil, logical.ErrorResponse("invalid certificate or no client certificate supplied"), nil
}
// Search for a ParsedCert that intersects with the validated chains and any additional constraints
matches := make([]*ParsedCert, 0)
for _, trust := range trusted { // For each ParsedCert in the config
for _, tCert := range trust.Certificates { // For each certificate in the entry
for _, chain := range trustedChains { // For each root chain that we matched
for _, cCert := range chain { // For each cert in the matched chain
if tCert.Equal(cCert) && // ParsedCert intersects with matched chain
b.matchesConstraints(clientCert, chain, trust) { // validate client cert + matched chain against the config
// Add the match to the list
matches = append(matches, trust)
}
}
}
}
}
// Fail on no matches
if len(matches) == 0 {
return nil, logical.ErrorResponse("no chain matching all constraints could be found for this login certificate"), nil
}
// Return the first matching entry (for backwards compatibility, we continue to just pick one if multiple match)
return matches[0], nil, nil
}
func (b *backend) matchesConstraints(clientCert *x509.Certificate, trustedChain []*x509.Certificate, config *ParsedCert) bool {
return !b.checkForChainInCRLs(trustedChain) &&
b.matchesNames(clientCert, config) &&
b.matchesCommonName(clientCert, config) &&
b.matchesDNSSANs(clientCert, config) &&
b.matchesEmailSANs(clientCert, config) &&
b.matchesURISANs(clientCert, config) &&
b.matchesCertificateExtensions(clientCert, config)
}
// matchesNames verifies that the certificate matches at least one configured
// allowed name
func (b *backend) matchesNames(clientCert *x509.Certificate, config *ParsedCert) bool {
// Default behavior (no names) is to allow all names
if len(config.Entry.AllowedNames) == 0 {
return true
}
// At least one pattern must match at least one name if any patterns are specified
for _, allowedName := range config.Entry.AllowedNames {
if glob.Glob(allowedName, clientCert.Subject.CommonName) {
return true
}
for _, name := range clientCert.DNSNames {
if glob.Glob(allowedName, name) {
return true
}
}
for _, name := range clientCert.EmailAddresses {
if glob.Glob(allowedName, name) {
return true
}
}
}
return false
}
// matchesCommonName verifies that the certificate matches at least one configured
// allowed common name
func (b *backend) matchesCommonName(clientCert *x509.Certificate, config *ParsedCert) bool {
// Default behavior (no names) is to allow all names
if len(config.Entry.AllowedCommonNames) == 0 {
return true
}
// At least one pattern must match at least one name if any patterns are specified
for _, allowedCommonName := range config.Entry.AllowedCommonNames {
if glob.Glob(allowedCommonName, clientCert.Subject.CommonName) {
return true
}
}
return false
}
// matchesDNSSANs verifies that the certificate matches at least one configured
// allowed dns entry in the subject alternate name extension
func (b *backend) matchesDNSSANs(clientCert *x509.Certificate, config *ParsedCert) bool {
// Default behavior (no names) is to allow all names
if len(config.Entry.AllowedDNSSANs) == 0 {
return true
}
// At least one pattern must match at least one name if any patterns are specified
for _, allowedDNS := range config.Entry.AllowedDNSSANs {
for _, name := range clientCert.DNSNames {
if glob.Glob(allowedDNS, name) {
return true
}
}
}
return false
}
// matchesEmailSANs verifies that the certificate matches at least one configured
// allowed email in the subject alternate name extension
func (b *backend) matchesEmailSANs(clientCert *x509.Certificate, config *ParsedCert) bool {
// Default behavior (no names) is to allow all names
if len(config.Entry.AllowedEmailSANs) == 0 {
return true
}
// At least one pattern must match at least one name if any patterns are specified
for _, allowedEmail := range config.Entry.AllowedEmailSANs {
for _, email := range clientCert.EmailAddresses {
if glob.Glob(allowedEmail, email) {
return true
}
}
}
return false
}
// matchesURISANs verifies that the certificate matches at least one configured
// allowed uri in the subject alternate name extension
func (b *backend) matchesURISANs(clientCert *x509.Certificate, config *ParsedCert) bool {
// Default behavior (no names) is to allow all names
if len(config.Entry.AllowedURISANs) == 0 {
return true
}
// At least one pattern must match at least one name if any patterns are specified
for _, allowedURI := range config.Entry.AllowedURISANs {
for _, name := range clientCert.URIs {
if glob.Glob(allowedURI, name.String()) {
return true
}
}
}
return false
}
// matchesCertificateExtensions verifies that the certificate matches configured
// required extensions
func (b *backend) matchesCertificateExtensions(clientCert *x509.Certificate, config *ParsedCert) bool {
// If no required extensions, nothing to check here
if len(config.Entry.RequiredExtensions) == 0 {
return true
}
// Fail fast if we have required extensions but no extensions on the cert
if len(clientCert.Extensions) == 0 {
return false
}
// Build Client Extensions Map for Constraint Matching
// x509 Writes Extensions in ASN1 with a bitstring tag, which results in the field
// including its ASN.1 type tag bytes. For the sake of simplicity, assume string type
// and drop the tag bytes. And get the number of bytes from the tag.
clientExtMap := make(map[string]string, len(clientCert.Extensions))
for _, ext := range clientCert.Extensions {
var parsedValue string
asn1.Unmarshal(ext.Value, &parsedValue)
clientExtMap[ext.Id.String()] = parsedValue
}
// If any of the required extensions don't match the constraint fails
for _, requiredExt := range config.Entry.RequiredExtensions {
reqExt := strings.SplitN(requiredExt, ":", 2)
clientExtValue, clientExtValueOk := clientExtMap[reqExt[0]]
if !clientExtValueOk || !glob.Glob(reqExt[1], clientExtValue) {
return false
}
}
return true
}
// loadTrustedCerts is used to load all the trusted certificates from the backend
func (b *backend) loadTrustedCerts(ctx context.Context, storage logical.Storage, certName string) (pool *x509.CertPool, trusted []*ParsedCert, trustedNonCAs []*ParsedCert) {
pool = x509.NewCertPool()
trusted = make([]*ParsedCert, 0)
trustedNonCAs = make([]*ParsedCert, 0)
names, err := storage.List(ctx, "cert/")
if err != nil {
b.Logger().Error("failed to list trusted certs", "error", err)
return
}
for _, name := range names {
// If we are trying to select a single CertEntry and this isn't it
if certName != "" && name != certName {
continue
}
entry, err := b.Cert(ctx, storage, strings.TrimPrefix(name, "cert/"))
if err != nil {
b.Logger().Error("failed to load trusted cert", "name", name, "error", err)
continue
}
parsed := parsePEM([]byte(entry.Certificate))
if len(parsed) == 0 {
b.Logger().Error("failed to parse certificate", "name", name)
continue
}
if !parsed[0].IsCA {
trustedNonCAs = append(trustedNonCAs, &ParsedCert{
Entry: entry,
Certificates: parsed,
})
} else {
for _, p := range parsed {
pool.AddCert(p)
}
// Create a ParsedCert entry
trusted = append(trusted, &ParsedCert{
Entry: entry,
Certificates: parsed,
})
}
}
return
}
func (b *backend) checkForChainInCRLs(chain []*x509.Certificate) bool {
badChain := false
for _, cert := range chain {
badCRLs := b.findSerialInCRLs(cert.SerialNumber)
if len(badCRLs) != 0 {
badChain = true
break
}
}
return badChain
}
func (b *backend) checkForValidChain(chains [][]*x509.Certificate) bool {
for _, chain := range chains {
if !b.checkForChainInCRLs(chain) {
return true
}
}
return false
}
func (b *backend) checkCIDR(cert *CertEntry, req *logical.Request) error {
if cidrutil.RemoteAddrIsOk(req.Connection.RemoteAddr, cert.BoundCIDRs) {
return nil
}
return logical.ErrPermissionDenied
}
// parsePEM parses a PEM encoded x509 certificate
func parsePEM(raw []byte) (certs []*x509.Certificate) {
for len(raw) > 0 {
var block *pem.Block
block, raw = pem.Decode(raw)
if block == nil {
break
}
if (block.Type != "CERTIFICATE" && block.Type != "TRUSTED CERTIFICATE") || len(block.Headers) != 0 {
continue
}
cert, err := x509.ParseCertificate(block.Bytes)
if err != nil {
continue
}
certs = append(certs, cert)
}
return
}
// validateConnState is used to validate that the TLS client is authorized
// by at trusted certificate. Most of this logic is lifted from the client
// verification logic here: http://golang.org/src/crypto/tls/handshake_server.go
// The trusted chains are returned.
func validateConnState(roots *x509.CertPool, cs *tls.ConnectionState) ([][]*x509.Certificate, error) {
certs := cs.PeerCertificates
if len(certs) == 0 {
return nil, nil
}
opts := x509.VerifyOptions{
Roots: roots,
Intermediates: x509.NewCertPool(),
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
}
if len(certs) > 1 {
for _, cert := range certs[1:] {
opts.Intermediates.AddCert(cert)
}
}
chains, err := certs[0].Verify(opts)
if err != nil {
if _, ok := err.(x509.UnknownAuthorityError); ok {
return nil, nil
}
return nil, errors.New("failed to verify client's certificate: " + err.Error())
}
return chains, nil
}