Vault SSH: Script to install dynamic keys in target

builtin/logical/ssh/backend_test.go

@@ -2,6 +2,7 @@ package ssh
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os/user"
 	"strings"
 	"testing"
@@ -57,13 +58,14 @@ var testOTP string
 var testPort string
 var testUserName string
 var testAdminUser string
+var testInstallScript string
 
 // Starts the server and initializes the servers IP address,
 // port and usernames to be used by the test cases.
 func init() {
 	addr, err := vault.StartTestServer()
 	if err != nil {
-		panic(fmt.Sprintf("Error starting mock server:%s", err))
+		panic(fmt.Sprintf("error starting mock server:%s", err))
 	}
 	input := strings.Split(addr, ":")
 	testIP = input[0]
@@ -71,10 +73,16 @@ func init() {
 
 	u, err := user.Current()
 	if err != nil {
-		panic(fmt.Sprintf("Error getting current username: '%s'", err))
+		panic(fmt.Sprintf("error getting current username: '%s'", err))
 	}
 	testUserName = u.Username
 	testAdminUser = u.Username
+	scriptBytes, err := ioutil.ReadFile("scripts/key-install-linux.sh")
+	if err != nil {
+		panic(fmt.Sprintf("error reading install script file: '%s'", err))
+	}
+	testInstallScript = string(scriptBytes)
+
 }
 
 func TestSSHBackend_Lookup(t *testing.T) {
@@ -87,10 +95,11 @@ func TestSSHBackend_Lookup(t *testing.T) {
 		"cidr":         testCidr,
 	}
 	dynamicData := map[string]interface{}{
-		"key_type":   testDynamicKeyType,
-		"key":        testKeyName,
-		"admin_user": testAdminUser,
-		"cidr":       testCidr,
+		"key_type":       testDynamicKeyType,
+		"key":            testKeyName,
+		"admin_user":     testAdminUser,
+		"cidr":           testCidr,
+		"install_script": testInstallScript,
 	}
 	logicaltest.Test(t, logicaltest.TestCase{
 		Factory: Factory,
@@ -139,10 +148,11 @@ func TestSSHBackend_OTPRoleCrud(t *testing.T) {
 
 func TestSSHBackend_DynamicRoleCrud(t *testing.T) {
 	data := map[string]interface{}{
-		"key_type":   testDynamicKeyType,
-		"key":        testKeyName,
-		"admin_user": testAdminUser,
-		"cidr":       testCidr,
+		"key_type":       testDynamicKeyType,
+		"key":            testKeyName,
+		"admin_user":     testAdminUser,
+		"cidr":           testCidr,
+		"install_script": testInstallScript,
 	}
 	logicaltest.Test(t, logicaltest.TestCase{
 		Factory: Factory,
@@ -318,11 +328,12 @@ func testNewDynamicKeyRole(t *testing.T) logicaltest.TestStep {
 		Operation: logical.WriteOperation,
 		Path:      fmt.Sprintf("roles/%s", testDynamicRoleName),
 		Data: map[string]interface{}{
-			"key_type":   "dynamic",
-			"key":        testKeyName,
-			"admin_user": testAdminUser,
-			"cidr":       testCidr,
-			"port":       testPort,
+			"key_type":       "dynamic",
+			"key":            testKeyName,
+			"admin_user":     testAdminUser,
+			"cidr":           testCidr,
+			"port":           testPort,
+			"install_script": testInstallScript,
 		},
 	}
 }

builtin/logical/ssh/path_creds_create.go

@@ -165,9 +165,14 @@ func (b *backend) GenerateDynamicCredential(req *logical.Request, role *sshRole,
 
 	// Transfer the public key to target machine
 	publicKeyFileName := uuid.GenerateUUID()
-	err = uploadPublicKeyScp(dynamicPublicKey, publicKeyFileName, username, ip, role.Port, hostKey.Key)
+	scriptFileName := publicKeyFileName + ".sh"
+	err = scpUpload(role.AdminUser, ip, role.Port, hostKey.Key, publicKeyFileName, dynamicPublicKey)
 	if err != nil {
-		return "", "", err
+		return "", "", fmt.Errorf("error uploading public key: %s", err)
+	}
+	err = scpUpload(role.AdminUser, ip, role.Port, hostKey.Key, scriptFileName, role.InstallScript)
+	if err != nil {
+		return "", "", fmt.Errorf("error uploading install script: %s", err)
 	}
 
 	// Add the public key to authorized_keys file in target machine

builtin/logical/ssh/path_roles.go

@@ -50,6 +50,10 @@ func pathRoles(b *backend) *framework.Path {
 				Type:        framework.TypeString,
 				Description: "number of bits in keys",
 			},
+			"install_script": &framework.FieldSchema{
+				Type:        framework.TypeString,
+				Description: "script that installs public key in target",
+			},
 		},
 
 		Callbacks: map[logical.Operation]framework.OperationFunc{
@@ -120,6 +124,11 @@ func (b *backend) pathRoleWrite(req *logical.Request, d *framework.FieldData) (*
 			return logical.ErrorResponse(fmt.Sprintf("Invalid 'key': '%s'", keyName)), nil
 		}
 
+		installScript := d.Get("install_script").(string)
+		if installScript == "" {
+			return logical.ErrorResponse("Missing install script"), nil
+		}
+
 		adminUser := d.Get("admin_user").(string)
 		if adminUser == "" {
 			return logical.ErrorResponse("Missing admin username"), nil
@@ -142,13 +151,14 @@ func (b *backend) pathRoleWrite(req *logical.Request, d *framework.FieldData) (*
 		}
 
 		entry, err = logical.StorageEntryJSON(fmt.Sprintf("policy/%s", roleName), sshRole{
-			KeyName:     keyName,
-			AdminUser:   adminUser,
-			DefaultUser: defaultUser,
-			CIDR:        cidr,
-			Port:        port,
-			KeyType:     KeyTypeDynamic,
-			KeyBits:     keyBits,
+			KeyName:       keyName,
+			AdminUser:     adminUser,
+			DefaultUser:   defaultUser,
+			CIDR:          cidr,
+			Port:          port,
+			KeyType:       KeyTypeDynamic,
+			KeyBits:       keyBits,
+			InstallScript: installScript,
 		})
 	} else {
 		return logical.ErrorResponse("Invalid key type"), nil
@@ -212,13 +222,14 @@ func (b *backend) pathRoleDelete(req *logical.Request, d *framework.FieldData) (
 }
 
 type sshRole struct {
-	KeyType     string `mapstructure:"key_type" json:"key_type"`
-	KeyName     string `mapstructure:"key" json:"key"`
-	KeyBits     string `mapstructure:"key_bits" json:"key_bits"`
-	AdminUser   string `mapstructure:"admin_user" json:"admin_user"`
-	DefaultUser string `mapstructure:"default_user" json:"default_user"`
-	CIDR        string `mapstructure:"cidr" json:"cidr"`
-	Port        string `mapstructure:"port" json:"port"`
+	KeyType       string `mapstructure:"key_type" json:"key_type"`
+	KeyName       string `mapstructure:"key" json:"key"`
+	KeyBits       string `mapstructure:"key_bits" json:"key_bits"`
+	AdminUser     string `mapstructure:"admin_user" json:"admin_user"`
+	DefaultUser   string `mapstructure:"default_user" json:"default_user"`
+	CIDR          string `mapstructure:"cidr" json:"cidr"`
+	Port          string `mapstructure:"port" json:"port"`
+	InstallScript string `mapstructure:"install_script" json:"install_script"`
 }
 
 const pathRoleHelpSyn = `

builtin/logical/ssh/scripts/key-install-linux.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+#
+# This script file adds a RSA public key to the authoried_keys file in a typical
+# linux machine. This script should be registered with vault server while creating
+# a role for key type 'dynamic'.
+#
+# Vault server runs this script on the target machine with the following params:
+# $1: File containing public key to be installed. Vault server uses UUID as file
+# name to avoid collisions with public keys generated for requests.
+#
+# $2: Absolute path of the authorized_keys file.
+#
+# [Note: Modify the script if targt machine does not have the commands used in
+# this script]
+
+# If the key being installed is already present in the authorized_keys file, it is
+# removed and the result is stored in a temporary file.
+grep -vFf $1 $2 > temp_$1
+
+# Contents of temporary file will be the contents of authorized_keys file.
+cat temp_$1 > $2
+
+# New public key is appended to authorized_keys file
+cat $1 >> $2
+
+# Auxiliary files are deleted
+rm -f $1 temp_$1

builtin/logical/ssh/util.go

@@ -1,6 +1,7 @@
 package ssh
 
 import (
+	"bytes"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/x509"
@@ -10,9 +11,11 @@ import (
 	"io"
 	"net"
 	"strings"
+	"time"
 
 	"github.com/hashicorp/vault/logical"
 
+	commssh "github.com/mitchellh/packer/communicator/ssh"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -104,8 +107,8 @@ func generateRSAKeys(keyBits int) (publicKeyRsa string, privateKeyRsa string, er
 
 // Concatenates the public present in that target machine's home
 // folder to ~/.ssh/authorized_keys file
-func installPublicKeyInTarget(adminUser, publicKeyFileName, username, ip, port, hostKey string) error {
-	session, err := createSSHPublicKeysSession(adminUser, ip, port, hostKey)
+func installPublicKeyInTarget(adminUser, publicKeyFileName, username, ip, port, hostkey string) error {
+	session, err := createSSHPublicKeysSession(adminUser, ip, port, hostkey)
 	if err != nil {
 		return fmt.Errorf("unable to create SSH Session using public keys: %s", err)
 	}
@@ -115,15 +118,14 @@ func installPublicKeyInTarget(adminUser, publicKeyFileName, username, ip, port,
 	defer session.Close()
 
 	authKeysFileName := fmt.Sprintf("/home/%s/.ssh/authorized_keys", username)
-	tempKeysFileName := fmt.Sprintf("/home/%s/temp_authorized_keys", username)
 
-	// Commands to be run on target machine
-	grepCmd := fmt.Sprintf("grep -vFf %s %s > %s", publicKeyFileName, authKeysFileName, tempKeysFileName)
-	catCmdRemoveDuplicate := fmt.Sprintf("cat %s > %s", tempKeysFileName, authKeysFileName)
-	catCmdAppendNew := fmt.Sprintf("cat %s >> %s", publicKeyFileName, authKeysFileName)
-	removeCmd := fmt.Sprintf("rm -f %s %s", tempKeysFileName, publicKeyFileName)
+	// Give execute permissions to install script, run and delete it.
+	scriptFileName := publicKeyFileName + ".sh"
+	chmodCmd := fmt.Sprintf("chmod +x %s", scriptFileName)
+	scriptCmd := fmt.Sprintf("./%s %s %s", scriptFileName, publicKeyFileName, authKeysFileName)
+	rmCmd := fmt.Sprintf("rm -f %s", scriptFileName)
+	targetCmd := fmt.Sprintf("%s;%s;%s", chmodCmd, scriptCmd, rmCmd)
 
-	targetCmd := fmt.Sprintf("%s;%s;%s;%s", grepCmd, catCmdRemoveDuplicate, catCmdAppendNew, removeCmd)
 	session.Run(targetCmd)
 	return nil
 }
@@ -198,3 +200,39 @@ func cidrContainsIP(ip, cidr string) (bool, error) {
 	}
 	return false, nil
 }
+
+func scpUpload(username, ip, port, hostkey, fileName, fileContent string) error {
+	signer, err := ssh.ParsePrivateKey([]byte(hostkey))
+	clientConfig := &ssh.ClientConfig{
+		User: username,
+		Auth: []ssh.AuthMethod{
+			ssh.PublicKeys(signer),
+		},
+	}
+
+	connfunc := func() (net.Conn, error) {
+		c, err := net.DialTimeout("tcp", fmt.Sprintf("%s:%s", ip, port), 15*time.Second)
+		if err != nil {
+			return nil, err
+		}
+
+		if tcpConn, ok := c.(*net.TCPConn); ok {
+			tcpConn.SetKeepAlive(true)
+			tcpConn.SetKeepAlivePeriod(5 * time.Second)
+		}
+
+		return c, nil
+	}
+	config := &commssh.Config{
+		SSHConfig:    clientConfig,
+		Connection:   connfunc,
+		Pty:          false,
+		DisableAgent: true,
+	}
+	comm, err := commssh.New(fmt.Sprintf("%s:%s", ip, port), config)
+	if err != nil {
+		return fmt.Errorf("error connecting to target: %s", err)
+	}
+	comm.Upload(fileName, bytes.NewBufferString(fileContent), nil)
+	return nil
+}