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/*
Copyright 2019 Stellar Project
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in the
Software without restriction, including without limitation the rights to use, copy,
modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
and to permit persons to whom the Software is furnished to do so, subject to the
following conditions:
The above copyright notice and this permission notice shall be included in all copies
or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package main
import (
"bytes"
"context"
"fmt"
"io"
"io/ioutil"
"net"
"os"
"path"
"path/filepath"
"sync"
"time"
v1 "github.com/crosbymichael/guard/api/v1"
"github.com/gliderlabs/ssh"
"github.com/gomodule/redigo/redis"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"google.golang.org/grpc"
)
const (
ipsKey = "gatekeeper/ips"
configKeyPrefix = "gatekeeper/config/"
)
type ServerConfig struct {
ListenPort int
DBPath string
KeysPath string
HostKeyPath string
RedisURL string
Subnet string
GuardAddr string
GuardTunnel string
GuardDNS string
}
type Server struct {
cfg *ServerConfig
publicKeys []ssh.PublicKey
mu *sync.Mutex
}
func NewServer(cfg *ServerConfig) (*Server, error) {
if cfg.ListenPort == 0 {
cfg.ListenPort = 2222
}
return &Server{
cfg: cfg,
mu: &sync.Mutex{},
}, nil
}
func (s *Server) Run() error {
if err := s.loadKeys(); err != nil {
return err
}
ssh.Handle(func(session ssh.Session) {
id := s.getID(session.PublicKey())
config, err := s.getConfig(id)
if err != nil {
logrus.Error(err)
return
}
logrus.Debugf("config: id=%s", id)
io.WriteString(session, config)
})
pubKeyOption := ssh.PublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) bool {
return s.isAuthorized(ctx, key)
})
logrus.Infof("starting ssh server on port %d", s.cfg.ListenPort)
opts := []ssh.Option{
pubKeyOption,
}
if _, err := os.Stat(s.cfg.HostKeyPath); err == nil {
opts = append(opts, ssh.HostKeyFile(s.cfg.HostKeyPath))
}
return ssh.ListenAndServe(fmt.Sprintf(":%d", s.cfg.ListenPort), nil, opts...)
}
func (s *Server) loadKeys() error {
s.mu.Lock()
defer s.mu.Unlock()
if s.cfg.KeysPath == "" {
return nil
}
keys, err := ioutil.ReadDir(s.cfg.KeysPath)
if err != nil {
return err
}
pubKeys := []ssh.PublicKey{}
for _, k := range keys {
logrus.Debugf("loading public key %s", k.Name())
p := filepath.Join(s.cfg.KeysPath, k.Name())
data, err := ioutil.ReadFile(p)
if err != nil {
return err
}
k, _, _, _, err := ssh.ParseAuthorizedKey(data)
if err != nil {
return err
}
pubKeys = append(pubKeys, k)
}
s.publicKeys = pubKeys
return nil
}
func (s *Server) isAuthorized(ctx ssh.Context, key ssh.PublicKey) bool {
for _, k := range s.publicKeys {
if ssh.KeysEqual(key, k) {
return true
}
}
logrus.WithFields(logrus.Fields{
"user": ctx.User(),
"addr": ctx.RemoteAddr(),
}).Warn("access denied")
return false
}
func (s *Server) getConfig(id string) (string, error) {
c, err := s.getConn()
if err != nil {
return "", err
}
defer c.Close()
key := path.Join(configKeyPrefix, id)
cfg, err := redis.String(c.Do("GET", key))
if err != nil && err != redis.ErrNil {
return "", err
}
if cfg != "" {
return cfg, nil
}
conn, err := grpc.Dial(s.cfg.GuardAddr, grpc.WithInsecure())
if err != nil {
return "", errors.Wrap(err, "error connecting to guard server")
}
defer conn.Close()
ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
defer cancel()
client := v1.NewWireguardClient(conn)
ip, ipnet, err := s.getOrAllocateIP(id, s.cfg.Subnet)
if err != nil {
return "", err
}
r, err := client.NewPeer(ctx, &v1.NewPeerRequest{
ID: s.cfg.GuardTunnel,
PeerID: id,
Address: ip.String() + "/32",
})
if err != nil {
return "", err
}
// generate peer tunnel config
t := &v1.Tunnel{
PrivateKey: r.Peer.PrivateKey,
Address: r.Peer.AllowedIPs[0],
DNS: s.cfg.GuardDNS,
Peers: []*v1.Peer{
{
ID: r.Tunnel.ID,
PublicKey: r.Tunnel.PublicKey,
Endpoint: net.JoinHostPort(r.Tunnel.Endpoint, r.Tunnel.ListenPort),
AllowedIPs: []string{ipnet.String()},
},
},
}
b := bytes.NewBuffer(nil)
t.Render(b)
if _, err := c.Do("SET", key, b.String()); err != nil {
return "", err
}
return b.String(), nil
}