Ignore principals validations with OIDC

This commit will ignore principals validation when an OIDC provisioner
is used. When the principals in the server does not match the principals
given the validation was failing, even if the proper principals were set
by templates or webhooks. With this change OIDC will not validate the
principals and just set the default ones (name, name@example.org) plus
the ones in the templates.

This commit also includes a change in the templates to allow to pass
a provisioner to the $(step path)/ssh/config template

Related to #807

authority/provisioner/oidc.go

@@ -385,16 +385,13 @@ func (o *OIDC) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption
 	}
 
 	var data sshutil.TemplateData
-	var principals []string
-
 	if claims.Email == "" {
-		// If email is empty, use the Subject claim instead to create minimal data for the template to use
+		// If email is empty, use the Subject claim instead to create minimal
+		// data for the template to use.
 		data = sshutil.CreateTemplateData(sshutil.UserCert, claims.Subject, nil)
 		if v, err := unsafeParseSigned(token); err == nil {
 			data.SetToken(v)
 		}
-
-		principals = nil
 	} else {
 		// Get the identity using either the default identityFunc or one injected
 		// externally. Note that the PreferredUsername might be empty.
@@ -417,8 +414,6 @@ func (o *OIDC) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption
 		for k, v := range iden.Permissions.CriticalOptions {
 			data.AddCriticalOption(k, v)
 		}
-
-		principals = iden.Usernames
 	}
 
 	// Use the default template unless no-templates are configured and email is
@@ -446,8 +441,7 @@ func (o *OIDC) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption
 		})
 	} else {
 		signOptions = append(signOptions, sshCertOptionsValidator(SignSSHOptions{
-			CertType:   SSHUserCert,
-			Principals: principals,
+			CertType: SSHUserCert,
 		}))
 	}
 

authority/provisioner/oidc_test.go

@@ -582,6 +582,9 @@ func TestOIDC_AuthorizeSSHSign(t *testing.T) {
 		{"ok-principals", p1, args{t1, SignSSHOptions{Principals: []string{"name"}}, pub},
 			&SignSSHOptions{CertType: "user", Principals: []string{"name", "name@smallstep.com"},
 				ValidAfter: NewTimeDuration(tm), ValidBefore: NewTimeDuration(tm.Add(userDuration))}, http.StatusOK, false, false},
+		{"ok-principals-ignore-passed", p1, args{t1, SignSSHOptions{Principals: []string{"root"}}, pub},
+			&SignSSHOptions{CertType: "user", Principals: []string{"name", "name@smallstep.com"},
+				ValidAfter: NewTimeDuration(tm), ValidBefore: NewTimeDuration(tm.Add(userDuration))}, http.StatusOK, false, false},
 		{"ok-principals-getIdentity", p4, args{okGetIdentityToken, SignSSHOptions{Principals: []string{"mariano"}}, pub},
 			&SignSSHOptions{CertType: "user", Principals: []string{"max", "mariano"},
 				ValidAfter: NewTimeDuration(tm), ValidBefore: NewTimeDuration(tm.Add(userDuration))}, http.StatusOK, false, false},
@@ -600,7 +603,6 @@ func TestOIDC_AuthorizeSSHSign(t *testing.T) {
 				ValidAfter: NewTimeDuration(tm), ValidBefore: NewTimeDuration(tm.Add(userDuration))}, http.StatusOK, false, false},
 		{"fail-rsa1024", p1, args{t1, SignSSHOptions{}, rsa1024.Public()}, expectedUserOptions, http.StatusOK, false, true},
 		{"fail-user-host", p1, args{t1, SignSSHOptions{CertType: "host"}, pub}, nil, http.StatusOK, false, true},
-		{"fail-user-principals", p1, args{t1, SignSSHOptions{Principals: []string{"root"}}, pub}, nil, http.StatusOK, false, true},
 		{"fail-getIdentity", p5, args{failGetIdentityToken, SignSSHOptions{}, pub}, nil, http.StatusInternalServerError, true, false},
 		{"fail-sshCA-disabled", p6, args{"foo", SignSSHOptions{}, pub}, nil, http.StatusUnauthorized, true, false},
 		// Missing parametrs

templates/values.go

@@ -108,10 +108,10 @@ var DefaultSSHTemplateData = map[string]string{
 {{- end }}
 {{- if or .User.GOOS "none" | eq "windows" }}
 	UserKnownHostsFile "{{.User.StepPath}}\ssh\known_hosts"
-	ProxyCommand C:\Windows\System32\cmd.exe /c step ssh proxycommand{{- if .User.Context }} --context {{ .User.Context }}{{- end }} %r %h %p
+	ProxyCommand C:\Windows\System32\cmd.exe /c step ssh proxycommand{{- if .User.Context }} --context {{ .User.Context }}{{- end }}{{- if .User.Provisioner }} --provisioner {{ .User.Provisioner }}{{- end }} %r %h %p
 {{- else }}
 	UserKnownHostsFile "{{.User.StepPath}}/ssh/known_hosts"
-	ProxyCommand step ssh proxycommand{{- if .User.Context }} --context {{ .User.Context }}{{- end }} %r %h %p
+	ProxyCommand step ssh proxycommand{{- if .User.Context }} --context {{ .User.Context }}{{- end }}{{- if .User.Provisioner }} --provisioner {{ .User.Provisioner }}{{- end }} %r %h %p
 {{- end }}
 `,