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util.go
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util.go
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package ssh
import (
"bytes"
"context"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/base64"
"encoding/pem"
"fmt"
"net"
"strings"
"time"
"github.com/hashicorp/errwrap"
"github.com/hashicorp/vault/helper/parseutil"
"github.com/hashicorp/vault/logical"
log "github.com/hashicorp/go-hclog"
"golang.org/x/crypto/ssh"
)
// Creates a new RSA key pair with the given key length. The private key will be
// of pem format and the public key will be of OpenSSH format.
func generateRSAKeys(keyBits int) (publicKeyRsa string, privateKeyRsa string, err error) {
privateKey, err := rsa.GenerateKey(rand.Reader, keyBits)
if err != nil {
return "", "", errwrap.Wrapf("error generating RSA key-pair: {{err}}", err)
}
privateKeyRsa = string(pem.EncodeToMemory(&pem.Block{
Type: "RSA PRIVATE KEY",
Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
}))
sshPublicKey, err := ssh.NewPublicKey(privateKey.Public())
if err != nil {
return "", "", errwrap.Wrapf("error generating RSA key-pair: {{err}}", err)
}
publicKeyRsa = "ssh-rsa " + base64.StdEncoding.EncodeToString(sshPublicKey.Marshal())
return
}
// Public key and the script to install the key are uploaded to remote machine.
// Public key is either added or removed from authorized_keys file using the
// script. Default script is for a Linux machine and hence the path of the
// authorized_keys file is hard coded to resemble Linux.
//
// The last param 'install' if false, uninstalls the key.
func (b *backend) installPublicKeyInTarget(ctx context.Context, adminUser, username, ip string, port int, hostkey, dynamicPublicKey, installScript string, install bool) error {
// Transfer the newly generated public key to remote host under a random
// file name. This is to avoid name collisions from other requests.
_, publicKeyFileName, err := b.GenerateSaltedOTP(ctx)
if err != nil {
return err
}
comm, err := createSSHComm(b.Logger(), adminUser, ip, port, hostkey)
if err != nil {
return err
}
defer comm.Close()
err = comm.Upload(publicKeyFileName, bytes.NewBufferString(dynamicPublicKey), nil)
if err != nil {
return errwrap.Wrapf("error uploading public key: {{err}}", err)
}
// Transfer the script required to install or uninstall the key to the remote
// host under a random file name as well. This is to avoid name collisions
// from other requests.
scriptFileName := fmt.Sprintf("%s.sh", publicKeyFileName)
err = comm.Upload(scriptFileName, bytes.NewBufferString(installScript), nil)
if err != nil {
return errwrap.Wrapf("error uploading install script: {{err}}", err)
}
// Create a session to run remote command that triggers the script to install
// or uninstall the key.
session, err := comm.NewSession()
if err != nil {
return errwrap.Wrapf("unable to create SSH Session using public keys: {{err}}", err)
}
if session == nil {
return fmt.Errorf("invalid session object")
}
defer session.Close()
authKeysFileName := fmt.Sprintf("/home/%s/.ssh/authorized_keys", username)
var installOption string
if install {
installOption = "install"
} else {
installOption = "uninstall"
}
// Give execute permissions to install script, run and delete it.
chmodCmd := fmt.Sprintf("chmod +x %s", scriptFileName)
scriptCmd := fmt.Sprintf("./%s %s %s %s", scriptFileName, installOption, publicKeyFileName, authKeysFileName)
rmCmd := fmt.Sprintf("rm -f %s", scriptFileName)
targetCmd := fmt.Sprintf("%s;%s;%s", chmodCmd, scriptCmd, rmCmd)
session.Run(targetCmd)
return nil
}
// Takes an IP address and role name and checks if the IP is part
// of CIDR blocks belonging to the role.
func roleContainsIP(ctx context.Context, s logical.Storage, roleName string, ip string) (bool, error) {
if roleName == "" {
return false, fmt.Errorf("missing role name")
}
if ip == "" {
return false, fmt.Errorf("missing ip")
}
roleEntry, err := s.Get(ctx, fmt.Sprintf("roles/%s", roleName))
if err != nil {
return false, errwrap.Wrapf("error retrieving role {{err}}", err)
}
if roleEntry == nil {
return false, fmt.Errorf("role %q not found", roleName)
}
var role sshRole
if err := roleEntry.DecodeJSON(&role); err != nil {
return false, fmt.Errorf("error decoding role %q", roleName)
}
if matched, err := cidrListContainsIP(ip, role.CIDRList); err != nil {
return false, err
} else {
return matched, nil
}
}
// Returns true if the IP supplied by the user is part of the comma
// separated CIDR blocks
func cidrListContainsIP(ip, cidrList string) (bool, error) {
if len(cidrList) == 0 {
return false, fmt.Errorf("IP does not belong to role")
}
for _, item := range strings.Split(cidrList, ",") {
_, cidrIPNet, err := net.ParseCIDR(item)
if err != nil {
return false, fmt.Errorf("invalid CIDR entry %q", item)
}
if cidrIPNet.Contains(net.ParseIP(ip)) {
return true, nil
}
}
return false, nil
}
func createSSHComm(logger log.Logger, username, ip string, port int, hostkey string) (*comm, error) {
signer, err := ssh.ParsePrivateKey([]byte(hostkey))
if err != nil {
return nil, err
}
clientConfig := &ssh.ClientConfig{
User: username,
Auth: []ssh.AuthMethod{
ssh.PublicKeys(signer),
},
HostKeyCallback: ssh.InsecureIgnoreHostKey(),
}
connfunc := func() (net.Conn, error) {
c, err := net.DialTimeout("tcp", fmt.Sprintf("%s:%d", 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 := &SSHCommConfig{
SSHConfig: clientConfig,
Connection: connfunc,
Pty: false,
DisableAgent: true,
Logger: logger,
}
return SSHCommNew(fmt.Sprintf("%s:%d", ip, port), config)
}
func parsePublicSSHKey(key string) (ssh.PublicKey, error) {
keyParts := strings.Split(key, " ")
if len(keyParts) > 1 {
// Someone has sent the 'full' public key rather than just the base64 encoded part that the ssh library wants
key = keyParts[1]
}
decodedKey, err := base64.StdEncoding.DecodeString(key)
if err != nil {
return nil, err
}
return ssh.ParsePublicKey([]byte(decodedKey))
}
func convertMapToStringValue(initial map[string]interface{}) map[string]string {
result := map[string]string{}
for key, value := range initial {
result[key] = fmt.Sprintf("%v", value)
}
return result
}
func convertMapToIntValue(initial map[string]interface{}) (map[string]int, error) {
result := map[string]int{}
for key, value := range initial {
v, err := parseutil.ParseInt(value)
if err != nil {
return nil, err
}
result[key] = int(v)
}
return result, nil
}
// Serve a template processor for custom format inputs
func substQuery(tpl string, data map[string]string) string {
for k, v := range data {
tpl = strings.Replace(tpl, fmt.Sprintf("{{%s}}", k), v, -1)
}
return tpl
}