keyboard interactive: ask only the passcode if it is the second step

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/common/protocol_test.go

@@ -81,6 +81,45 @@ const (
 	osWindows             = "windows"
 	testFileName          = "test_file_common_sftp.dat"
 	testDir               = "test_dir_common"
+	testPubKey            = "ssh-rsa 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 nicola@p1"
+	testPrivateKey        = `-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAABlwAAAAdzc2gtcn
+NhAAAAAwEAAQAAAYEAtN449A/nY5O6cSH/9Doa8a3ISU0WZJaHydTaCLuO+dkqtNpnV5mq
+zFbKidXAI1eSwVctw9ReVOl1uK6aZF3lbXdOD8W9PXobR9KUUT2qBx5QC4ibfAqDKWymDA
+PG9ylzz64hsYBqJr7VNk9kTFEUsDmWzLabLoH42Elnp8mF/lTkWIcpVp0ly/etS08gttXo
+XenekJ1vRuxOYWDCEzGPU7kGc920TmM14k7IDdPoOh5+3sRUKedKeOUrVDH1f0n7QjHQsZ
+cbshp8tgqzf734zu8cTqNrr+6taptdEOOij1iUL/qYGfzny/hA48tO5+UFUih5W8ftp0+E
+NBIDkkGgk2MJ92I7QAXyMVsIABXco+mJT7pQi9tqlODGIQ3AOj0gcA3X/Ib8QX77Ih3TPi
+XEh77/P1XiYZOgpp2cRmNH8QbqaL9u898hDvJwIPJPuj2lIltTElH7hjBf5LQfCzrLV7BD
+10rM7sl4jr+A2q8jl1Ikp+25kainBBZSbrDummT9AAAFgDU/VLk1P1S5AAAAB3NzaC1yc2
+EAAAGBALTeOPQP52OTunEh//Q6GvGtyElNFmSWh8nU2gi7jvnZKrTaZ1eZqsxWyonVwCNX
+ksFXLcPUXlTpdbiummRd5W13Tg/FvT16G0fSlFE9qgceUAuIm3wKgylspgwDxvcpc8+uIb
+GAaia+1TZPZExRFLA5lsy2my6B+NhJZ6fJhf5U5FiHKVadJcv3rUtPILbV6F3p3pCdb0bs
+TmFgwhMxj1O5BnPdtE5jNeJOyA3T6Doeft7EVCnnSnjlK1Qx9X9J+0Ix0LGXG7IafLYKs3
++9+M7vHE6ja6/urWqbXRDjoo9YlC/6mBn858v4QOPLTuflBVIoeVvH7adPhDQSA5JBoJNj
+CfdiO0AF8jFbCAAV3KPpiU+6UIvbapTgxiENwDo9IHAN1/yG/EF++yId0z4lxIe+/z9V4m
+GToKadnEZjR/EG6mi/bvPfIQ7ycCDyT7o9pSJbUxJR+4YwX+S0Hws6y1ewQ9dKzO7JeI6/
+gNqvI5dSJKftuZGopwQWUm6w7ppk/QAAAAMBAAEAAAGAHKnC+Nq0XtGAkIFE4N18e6SAwy
+0WSWaZqmCzFQM0S2AhJnweOIG/0ZZHjsRzKKauOTmppQk40dgVsejpytIek9R+aH172gxJ
+2n4Cx0UwduRU5x8FFQlNc/kl722B0JWfJuB/snOZXv6LJ4o5aObIkozt2w9tVFeAqjYn2S
+1UsNOfRHBXGsTYwpRDwFWP56nKo2d2wBBTHDhCy6fb2dLW1fvSi/YspueOGIlHpvlYKi2/
+CWqvs9xVrwcScMtiDoQYq0khhO0efLCxvg/o+W9CLMVM2ms4G1zoSUQKN0oYWWQJyW4+VI
+YneWO8UpN0J3ElXKi7bhgAat7dBaM1g9IrAzk153DiEFZNsPxGOgL/+YdQN7zUBx/z7EkI
+jyv80RV7fpUXvcq2p+qNl6UVig3VSzRrnsaJkUWu/A0u59ha7ocv6NxDIXjxpIDJme16GF
+quiGVBQNnYJymS/vFEbGf6bgf7iRmMCRUMG4nqLA6fPYP9uAtch+CmDfVLZC/fIdC5AAAA
+wQCDissV4zH6bfqgxJSuYNk8Vbb+19cF3b7gH1rVlB3zxpCAgcRgMHC+dP1z2NRx7UW9MR
+nye6kjpkzZZ0OigLqo7TtEq8uTglD9o6W7mRXqhy5A/ySOmqPL3ernHHQhGuoNODYAHkOU
+u2Rh8HXi+VLwKZcLInPOYJvcuLG4DxN8WfeVvlMHwhAOaTNNOtL4XZDHQeIPc4qHmJymmv
+sV7GuyQ6yW5C10uoGdxRPd90Bh4z4h2bKfZFjvEBbSBVkqrlAAAADBAN/zNtNayd/dX7Cr
+Nb4sZuzCh+CW4BH8GOePZWNCATwBbNXBVb5cR+dmuTqYm+Ekz0VxVQRA1TvKncluJOQpoa
+Xj8r0xdIgqkehnfDPMKtYVor06B9Fl1jrXtXU0Vrr6QcBWruSVyK1ZxqcmcNK/+KolVepe
+A6vcl/iKaG4U7su166nxLST06M2EgcSVsFJHpKn5+WAXC+X0Gx8kNjWIIb3GpiChdc0xZD
+mq02xZthVJrTCVw/e7gfDoB2QRsNV8HwAAAMEAzsCghZVp+0YsYg9oOrw4tEqcbEXEMhwY
+0jW8JNL8Spr1Ibp5Dw6bRSk5azARjmJtnMJhJ3oeHfF0eoISqcNuQXGndGQbVM9YzzAzc1
+NbbCNsVroqKlChT5wyPNGS+phi2bPARBno7WSDvshTZ7dAVEP2c9MJW0XwoSevwKlhgSdt
+RLFFQ/5nclJSdzPBOmQouC0OBcMFSrYtMeknJ4VvueVvve5HcHFaEsaMc7ABAGaLYaBQOm
+iixITGvaNZh/tjAAAACW5pY29sYUBwMQE=
+-----END OPENSSH PRIVATE KEY-----`
 )
 
 var (
@@ -7812,6 +7851,69 @@ func TestBuiltinKeyboardInteractiveAuthentication(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestMultiStepBuiltinKeyboardAuth(t *testing.T) {
+	u := getTestUser()
+	u.PublicKeys = []string{testPubKey}
+	u.Filters.DeniedLoginMethods = []string{
+		dataprovider.SSHLoginMethodPublicKey,
+		dataprovider.LoginMethodPassword,
+		dataprovider.SSHLoginMethodKeyboardInteractive,
+	}
+	user, _, err := httpdtest.AddUser(u, http.StatusCreated)
+	assert.NoError(t, err)
+	signer, err := ssh.ParsePrivateKey([]byte(testPrivateKey))
+	assert.NoError(t, err)
+	// public key + password
+	authMethods := []ssh.AuthMethod{
+		ssh.PublicKeys(signer),
+		ssh.KeyboardInteractive(func(user, instruction string, questions []string, echos []bool) ([]string, error) {
+			return []string{defaultPassword}, nil
+		}),
+	}
+	conn, client, err := getCustomAuthSftpClient(user, authMethods)
+	if assert.NoError(t, err) {
+		defer conn.Close()
+		defer client.Close()
+		assert.NoError(t, checkBasicSFTP(client))
+		err = writeSFTPFile(testFileName, 4096, client)
+		assert.NoError(t, err)
+	}
+	// add multi-factor authentication
+	configName, key, _, err := mfa.GenerateTOTPSecret(mfa.GetAvailableTOTPConfigNames()[0], user.Username)
+	assert.NoError(t, err)
+	user.Password = defaultPassword
+	user.Filters.TOTPConfig = dataprovider.UserTOTPConfig{
+		Enabled:    true,
+		ConfigName: configName,
+		Secret:     kms.NewPlainSecret(key.Secret()),
+		Protocols:  []string{common.ProtocolSSH},
+	}
+	err = dataprovider.UpdateUser(&user, "", "", "")
+	assert.NoError(t, err)
+	passcode, err := generateTOTPPasscode(key.Secret(), otp.AlgorithmSHA1)
+	assert.NoError(t, err)
+	// public key + passcode
+	authMethods = []ssh.AuthMethod{
+		ssh.PublicKeys(signer),
+		ssh.KeyboardInteractive(func(user, instruction string, questions []string, echos []bool) ([]string, error) {
+			return []string{passcode}, nil
+		}),
+	}
+	conn, client, err = getCustomAuthSftpClient(user, authMethods)
+	if assert.NoError(t, err) {
+		defer conn.Close()
+		defer client.Close()
+		assert.NoError(t, checkBasicSFTP(client))
+		err = writeSFTPFile(testFileName, 4096, client)
+		assert.NoError(t, err)
+	}
+
+	_, err = httpdtest.RemoveUser(user, http.StatusOK)
+	assert.NoError(t, err)
+	err = os.RemoveAll(user.GetHomeDir())
+	assert.NoError(t, err)
+}
+
 func TestRenameSymlink(t *testing.T) {
 	u := getTestUser()
 	testDir := "/dir-no-create-links"