c7f226bcec
It supports renewing X.509 certificates when an RA is configured with stepcas. This will only work when the renewal uses a token, and it won't work with mTLS. The audience cannot be properly verified when an RA is used, to avoid this we will get from the database if an RA was used to issue the initial certificate and we will accept the renew token. Fixes #1021 for stepcas
475 lines
18 KiB
Go
475 lines
18 KiB
Go
package authority
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import (
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"context"
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"crypto/sha256"
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"crypto/x509"
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"encoding/hex"
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"fmt"
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"net/http"
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"net/url"
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"strconv"
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"strings"
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"time"
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"github.com/pkg/errors"
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"github.com/smallstep/certificates/authority/admin"
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"github.com/smallstep/certificates/authority/provisioner"
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"github.com/smallstep/certificates/errs"
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"go.step.sm/crypto/jose"
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"go.step.sm/linkedca"
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"golang.org/x/crypto/ssh"
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)
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// Claims extends jose.Claims with step attributes.
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type Claims struct {
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jose.Claims
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SANs []string `json:"sans,omitempty"`
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Email string `json:"email,omitempty"`
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Nonce string `json:"nonce,omitempty"`
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}
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type skipTokenReuseKey struct{}
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// NewContextWithSkipTokenReuse creates a new context from ctx and attaches a
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// value to skip the token reuse.
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func NewContextWithSkipTokenReuse(ctx context.Context) context.Context {
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return context.WithValue(ctx, skipTokenReuseKey{}, true)
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}
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// SkipTokenReuseFromContext returns if the token reuse needs to be ignored.
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func SkipTokenReuseFromContext(ctx context.Context) bool {
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m, _ := ctx.Value(skipTokenReuseKey{}).(bool)
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return m
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}
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// getProvisionerFromToken extracts a provisioner from the given token without
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// doing any token validation.
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func (a *Authority) getProvisionerFromToken(token string) (provisioner.Interface, *Claims, error) {
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tok, err := jose.ParseSigned(token)
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if err != nil {
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return nil, nil, fmt.Errorf("error parsing token: %w", err)
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}
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// Get claims w/out verification. We need to look up the provisioner
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// key in order to verify the claims and we need the issuer from the claims
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// before we can look up the provisioner.
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var claims Claims
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if err := tok.UnsafeClaimsWithoutVerification(&claims); err != nil {
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return nil, nil, fmt.Errorf("error unmarshaling token: %w", err)
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}
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// This method will also validate the audiences for JWK provisioners.
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p, ok := a.provisioners.LoadByToken(tok, &claims.Claims)
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if !ok {
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return nil, nil, fmt.Errorf("provisioner not found or invalid audience (%s)", strings.Join(claims.Audience, ", "))
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}
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return p, &claims, nil
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}
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// authorizeToken parses the token and returns the provisioner used to generate
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// the token. This method enforces the One-Time use policy (tokens can only be
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// used once).
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func (a *Authority) authorizeToken(ctx context.Context, token string) (provisioner.Interface, error) {
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p, claims, err := a.getProvisionerFromToken(token)
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if err != nil {
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return nil, errs.UnauthorizedErr(err)
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}
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// TODO: use new persistence layer abstraction.
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// Do not accept tokens issued before the start of the ca.
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// This check is meant as a stopgap solution to the current lack of a persistence layer.
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if a.config.AuthorityConfig != nil && !a.config.AuthorityConfig.DisableIssuedAtCheck {
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if claims.IssuedAt != nil && claims.IssuedAt.Time().Before(a.startTime) {
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return nil, errs.Unauthorized("token issued before the bootstrap of certificate authority")
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}
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}
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// Store the token to protect against reuse unless it's skipped.
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// If we cannot get a token id from the provisioner, just hash the token.
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if !SkipTokenReuseFromContext(ctx) {
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if err := a.UseToken(token, p); err != nil {
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return nil, err
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}
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}
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return p, nil
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}
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// AuthorizeAdminToken authorize an Admin token.
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func (a *Authority) AuthorizeAdminToken(r *http.Request, token string) (*linkedca.Admin, error) {
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jwt, err := jose.ParseSigned(token)
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if err != nil {
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return nil, admin.WrapError(admin.ErrorUnauthorizedType, err, "adminHandler.authorizeToken; error parsing x5c token")
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}
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verifiedChains, err := jwt.Headers[0].Certificates(x509.VerifyOptions{
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Roots: a.rootX509CertPool,
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KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
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})
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if err != nil {
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return nil, admin.WrapError(admin.ErrorUnauthorizedType, err,
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"adminHandler.authorizeToken; error verifying x5c certificate chain in token")
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}
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leaf := verifiedChains[0][0]
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if leaf.KeyUsage&x509.KeyUsageDigitalSignature == 0 {
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return nil, admin.NewError(admin.ErrorUnauthorizedType, "adminHandler.authorizeToken; certificate used to sign x5c token cannot be used for digital signature")
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}
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// Using the leaf certificates key to validate the claims accomplishes two
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// things:
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// 1. Asserts that the private key used to sign the token corresponds
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// to the public certificate in the `x5c` header of the token.
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// 2. Asserts that the claims are valid - have not been tampered with.
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var claims jose.Claims
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if err := jwt.Claims(leaf.PublicKey, &claims); err != nil {
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return nil, admin.WrapError(admin.ErrorUnauthorizedType, err, "adminHandler.authorizeToken; error parsing x5c claims")
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}
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prov, err := a.LoadProvisionerByCertificate(leaf)
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if err != nil {
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return nil, err
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}
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// Check that the token has not been used.
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if err := a.UseToken(token, prov); err != nil {
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return nil, admin.WrapError(admin.ErrorUnauthorizedType, err, "adminHandler.authorizeToken; error with reuse token")
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}
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// According to "rfc7519 JSON Web Token" acceptable skew should be no
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// more than a few minutes.
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if err := claims.ValidateWithLeeway(jose.Expected{
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Time: time.Now().UTC(),
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}, time.Minute); err != nil {
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return nil, admin.WrapError(admin.ErrorUnauthorizedType, err, "x5c.authorizeToken; invalid x5c claims")
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}
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// validate audience: path matches the current path
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if !matchesAudience(claims.Audience, a.config.Audience(r.URL.Path)) {
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return nil, admin.NewError(admin.ErrorUnauthorizedType, "x5c.authorizeToken; x5c token has invalid audience claim (aud)")
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}
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// validate issuer: old versions used the provisioner name, new version uses
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// 'step-admin-client/1.0'
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if claims.Issuer != "step-admin-client/1.0" && claims.Issuer != prov.GetName() {
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return nil, admin.NewError(admin.ErrorUnauthorizedType, "x5c.authorizeToken; x5c token has invalid issuer claim (iss)")
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}
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if claims.Subject == "" {
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return nil, admin.NewError(admin.ErrorUnauthorizedType, "x5c.authorizeToken; x5c token subject cannot be empty")
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}
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var (
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ok bool
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adm *linkedca.Admin
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)
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adminFound := false
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adminSANs := append([]string{leaf.Subject.CommonName}, leaf.DNSNames...)
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adminSANs = append(adminSANs, leaf.EmailAddresses...)
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for _, san := range adminSANs {
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if adm, ok = a.LoadAdminBySubProv(san, prov.GetName()); ok {
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adminFound = true
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break
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}
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}
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if !adminFound {
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return nil, admin.NewError(admin.ErrorUnauthorizedType,
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"adminHandler.authorizeToken; unable to load admin with subject(s) %s and provisioner '%s'",
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adminSANs, claims.Issuer)
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}
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if strings.HasPrefix(r.URL.Path, "/admin/admins") && (r.Method != "GET") && adm.Type != linkedca.Admin_SUPER_ADMIN {
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return nil, admin.NewError(admin.ErrorUnauthorizedType, "must have super admin access to make this request")
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}
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return adm, nil
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}
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// UseToken stores the token to protect against reuse.
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//
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// This method currently ignores any error coming from the GetTokenID, but it
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// should specifically ignore the error provisioner.ErrAllowTokenReuse.
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func (a *Authority) UseToken(token string, prov provisioner.Interface) error {
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if reuseKey, err := prov.GetTokenID(token); err == nil {
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if reuseKey == "" {
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sum := sha256.Sum256([]byte(token))
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reuseKey = strings.ToLower(hex.EncodeToString(sum[:]))
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}
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ok, err := a.db.UseToken(reuseKey, token)
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if err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "failed when attempting to store token")
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}
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if !ok {
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return errs.Unauthorized("token already used")
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}
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}
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return nil
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}
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// Authorize grabs the method from the context and authorizes the request by
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// validating the one-time-token.
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func (a *Authority) Authorize(ctx context.Context, token string) ([]provisioner.SignOption, error) {
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var opts = []interface{}{errs.WithKeyVal("token", token)}
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switch m := provisioner.MethodFromContext(ctx); m {
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case provisioner.SignMethod:
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signOpts, err := a.authorizeSign(ctx, token)
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return signOpts, errs.Wrap(http.StatusInternalServerError, err, "authority.Authorize", opts...)
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case provisioner.RevokeMethod:
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return nil, errs.Wrap(http.StatusInternalServerError, a.authorizeRevoke(ctx, token), "authority.Authorize", opts...)
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case provisioner.SSHSignMethod:
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if a.sshCAHostCertSignKey == nil && a.sshCAUserCertSignKey == nil {
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return nil, errs.NotImplemented("authority.Authorize; ssh certificate flows are not enabled", opts...)
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}
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signOpts, err := a.authorizeSSHSign(ctx, token)
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return signOpts, errs.Wrap(http.StatusInternalServerError, err, "authority.Authorize", opts...)
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case provisioner.SSHRenewMethod:
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if a.sshCAHostCertSignKey == nil && a.sshCAUserCertSignKey == nil {
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return nil, errs.NotImplemented("authority.Authorize; ssh certificate flows are not enabled", opts...)
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}
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_, err := a.authorizeSSHRenew(ctx, token)
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return nil, errs.Wrap(http.StatusInternalServerError, err, "authority.Authorize", opts...)
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case provisioner.SSHRevokeMethod:
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return nil, errs.Wrap(http.StatusInternalServerError, a.authorizeSSHRevoke(ctx, token), "authority.Authorize", opts...)
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case provisioner.SSHRekeyMethod:
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if a.sshCAHostCertSignKey == nil && a.sshCAUserCertSignKey == nil {
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return nil, errs.NotImplemented("authority.Authorize; ssh certificate flows are not enabled", opts...)
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}
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_, signOpts, err := a.authorizeSSHRekey(ctx, token)
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return signOpts, errs.Wrap(http.StatusInternalServerError, err, "authority.Authorize", opts...)
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default:
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return nil, errs.InternalServer("authority.Authorize; method %d is not supported", append([]interface{}{m}, opts...)...)
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}
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}
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// authorizeSign loads the provisioner from the token and calls the provisioner
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// AuthorizeSign method. Returns a list of methods to apply to the signing flow.
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func (a *Authority) authorizeSign(ctx context.Context, token string) ([]provisioner.SignOption, error) {
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p, err := a.authorizeToken(ctx, token)
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if err != nil {
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return nil, errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSign")
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}
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signOpts, err := p.AuthorizeSign(ctx, token)
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if err != nil {
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return nil, errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSign")
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}
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return signOpts, nil
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}
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// AuthorizeSign authorizes a signature request by validating and authenticating
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// a token that must be sent w/ the request.
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//
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// Deprecated: Use Authorize(context.Context, string) ([]provisioner.SignOption, error).
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func (a *Authority) AuthorizeSign(token string) ([]provisioner.SignOption, error) {
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ctx := NewContext(context.Background(), a)
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ctx = provisioner.NewContextWithMethod(ctx, provisioner.SignMethod)
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return a.Authorize(ctx, token)
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}
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// authorizeRevoke locates the provisioner used to generate the authenticating
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// token and then performs the token validation flow.
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func (a *Authority) authorizeRevoke(ctx context.Context, token string) error {
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p, err := a.authorizeToken(ctx, token)
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if err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeRevoke")
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}
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if err := p.AuthorizeRevoke(ctx, token); err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeRevoke")
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}
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return nil
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}
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// authorizeRenew locates the provisioner (using the provisioner extension in the cert), and checks
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// if for the configured provisioner, the renewal is enabled or not. If the
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// extra extension cannot be found, authorize the renewal by default.
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//
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// TODO(mariano): should we authorize by default?
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func (a *Authority) authorizeRenew(ctx context.Context, cert *x509.Certificate) error {
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serial := cert.SerialNumber.String()
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var opts = []interface{}{errs.WithKeyVal("serialNumber", serial)}
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isRevoked, err := a.IsRevoked(serial)
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if err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeRenew", opts...)
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}
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if isRevoked {
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return errs.Unauthorized("authority.authorizeRenew: certificate has been revoked", opts...)
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}
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p, err := a.LoadProvisionerByCertificate(cert)
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if err != nil {
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var ok bool
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// For backward compatibility this method will also succeed if the
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// certificate does not have a provisioner extension. LoadByCertificate
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// returns the noop provisioner if this happens, and it allows
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// certificate renewals.
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if p, ok = a.provisioners.LoadByCertificate(cert); !ok {
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return errs.Unauthorized("authority.authorizeRenew: provisioner not found", opts...)
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}
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}
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if err := p.AuthorizeRenew(ctx, cert); err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeRenew", opts...)
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}
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return nil
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}
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// authorizeSSHCertificate returns an error if the given certificate is revoked.
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func (a *Authority) authorizeSSHCertificate(ctx context.Context, cert *ssh.Certificate) error {
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var err error
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var isRevoked bool
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serial := strconv.FormatUint(cert.Serial, 10)
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if lca, ok := a.adminDB.(interface {
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IsSSHRevoked(string) (bool, error)
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}); ok {
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isRevoked, err = lca.IsSSHRevoked(serial)
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} else {
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isRevoked, err = a.db.IsSSHRevoked(serial)
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}
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if err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHCertificate", errs.WithKeyVal("serialNumber", serial))
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}
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if isRevoked {
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return errs.Unauthorized("authority.authorizeSSHCertificate: certificate has been revoked", errs.WithKeyVal("serialNumber", serial))
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}
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return nil
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}
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// authorizeSSHSign loads the provisioner from the token, checks that it has not
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// been used again and calls the provisioner AuthorizeSSHSign method. Returns a
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// list of methods to apply to the signing flow.
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func (a *Authority) authorizeSSHSign(ctx context.Context, token string) ([]provisioner.SignOption, error) {
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p, err := a.authorizeToken(ctx, token)
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if err != nil {
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return nil, errs.Wrap(http.StatusUnauthorized, err, "authority.authorizeSSHSign")
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}
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signOpts, err := p.AuthorizeSSHSign(ctx, token)
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if err != nil {
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return nil, errs.Wrap(http.StatusUnauthorized, err, "authority.authorizeSSHSign")
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}
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return signOpts, nil
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}
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// authorizeSSHRenew authorizes an SSH certificate renewal request, by
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// validating the contents of an SSHPOP token.
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func (a *Authority) authorizeSSHRenew(ctx context.Context, token string) (*ssh.Certificate, error) {
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p, err := a.authorizeToken(ctx, token)
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if err != nil {
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return nil, errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHRenew")
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}
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cert, err := p.AuthorizeSSHRenew(ctx, token)
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if err != nil {
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return nil, errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHRenew")
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}
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return cert, nil
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}
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// authorizeSSHRekey authorizes an SSH certificate rekey request, by
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// validating the contents of an SSHPOP token.
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func (a *Authority) authorizeSSHRekey(ctx context.Context, token string) (*ssh.Certificate, []provisioner.SignOption, error) {
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p, err := a.authorizeToken(ctx, token)
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if err != nil {
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return nil, nil, errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHRekey")
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}
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cert, signOpts, err := p.AuthorizeSSHRekey(ctx, token)
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if err != nil {
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return nil, nil, errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHRekey")
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}
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return cert, signOpts, nil
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}
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// authorizeSSHRevoke authorizes an SSH certificate revoke request, by
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// validating the contents of an SSHPOP token.
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func (a *Authority) authorizeSSHRevoke(ctx context.Context, token string) error {
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p, err := a.authorizeToken(ctx, token)
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if err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHRevoke")
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}
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if err = p.AuthorizeSSHRevoke(ctx, token); err != nil {
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return errs.Wrap(http.StatusInternalServerError, err, "authority.authorizeSSHRevoke")
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}
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return nil
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}
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// AuthorizeRenewToken validates the renew token and returns the leaf
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// certificate in the x5cInsecure header.
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func (a *Authority) AuthorizeRenewToken(ctx context.Context, ott string) (*x509.Certificate, error) {
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var claims jose.Claims
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jwt, chain, err := jose.ParseX5cInsecure(ott, a.rootX509Certs)
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if err != nil {
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return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token"))
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}
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leaf := chain[0][0]
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if err := jwt.Claims(leaf.PublicKey, &claims); err != nil {
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return nil, errs.InternalServerErr(err, errs.WithMessage("error validating renew token"))
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}
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p, err := a.LoadProvisionerByCertificate(leaf)
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if err != nil {
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return nil, errs.Unauthorized("error validating renew token: cannot get provisioner from certificate")
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}
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if err := a.UseToken(ott, p); err != nil {
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return nil, err
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}
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if err := claims.ValidateWithLeeway(jose.Expected{
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Subject: leaf.Subject.CommonName,
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Time: time.Now().UTC(),
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}, time.Minute); err != nil {
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switch {
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case errors.Is(err, jose.ErrInvalidIssuer):
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return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token: invalid issuer claim (iss)"))
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case errors.Is(err, jose.ErrInvalidSubject):
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return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token: invalid subject claim (sub)"))
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case errors.Is(err, jose.ErrNotValidYet):
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return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token: token not valid yet (nbf)"))
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case errors.Is(err, jose.ErrExpired):
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return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token: token is expired (exp)"))
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case errors.Is(err, jose.ErrIssuedInTheFuture):
|
|
return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token: token issued in the future (iat)"))
|
|
default:
|
|
return nil, errs.UnauthorizedErr(err, errs.WithMessage("error validating renew token"))
|
|
}
|
|
}
|
|
|
|
audiences := a.config.GetAudiences().Renew
|
|
if !matchesAudience(claims.Audience, audiences) && !isRAProvisioner(p) {
|
|
return nil, errs.InternalServerErr(jose.ErrInvalidAudience, errs.WithMessage("error validating renew token: invalid audience claim (aud)"))
|
|
}
|
|
|
|
// validate issuer: old versions used the provisioner name, new version uses
|
|
// 'step-ca-client/1.0'
|
|
if claims.Issuer != "step-ca-client/1.0" && claims.Issuer != p.GetName() {
|
|
return nil, admin.NewError(admin.ErrorUnauthorizedType, "error validating renew token: invalid issuer claim (iss)")
|
|
}
|
|
|
|
return leaf, nil
|
|
}
|
|
|
|
// matchesAudience returns true if A and B share at least one element.
|
|
func matchesAudience(as, bs []string) bool {
|
|
if len(bs) == 0 || len(as) == 0 {
|
|
return false
|
|
}
|
|
|
|
for _, b := range bs {
|
|
for _, a := range as {
|
|
if b == a || stripPort(a) == stripPort(b) {
|
|
return true
|
|
}
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// stripPort attempts to strip the port from the given url. If parsing the url
|
|
// produces errors it will just return the passed argument.
|
|
func stripPort(rawurl string) string {
|
|
u, err := url.Parse(rawurl)
|
|
if err != nil {
|
|
return rawurl
|
|
}
|
|
u.Host = u.Hostname()
|
|
return u.String()
|
|
}
|