lib/controller/localdb/container_gateway.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package localdb
   6
   7 import (
   8         "bufio"
   9         "context"
  10         "crypto/hmac"
  11         "crypto/sha256"
  12         "crypto/tls"
  13         "crypto/x509"
  14         "errors"
  15         "fmt"
  16         "net/http"
  17         "net/url"
  18         "strings"
  19
  20         "git.arvados.org/arvados.git/sdk/go/arvados"
  21         "git.arvados.org/arvados.git/sdk/go/auth"
  22         "git.arvados.org/arvados.git/sdk/go/ctxlog"
  23         "git.arvados.org/arvados.git/sdk/go/httpserver"
  24 )
  25
  26 // ContainerSSH returns a connection to the SSH server in the
  27 // appropriate crunch-run process on the worker node where the
  28 // specified container is running.
  29 //
  30 // If the returned error is nil, the caller is responsible for closing
  31 // sshconn.Conn.
  32 func (conn *Conn) ContainerSSH(ctx context.Context, opts arvados.ContainerSSHOptions) (sshconn arvados.ContainerSSHConnection, err error) {
  33         user, err := conn.railsProxy.UserGetCurrent(ctx, arvados.GetOptions{})
  34         if err != nil {
  35                 return
  36         }
  37         ctr, err := conn.railsProxy.ContainerGet(ctx, arvados.GetOptions{UUID: opts.UUID})
  38         if err != nil {
  39                 return
  40         }
  41         ctxRoot := auth.NewContext(ctx, &auth.Credentials{Tokens: []string{conn.cluster.SystemRootToken}})
  42         if !user.IsAdmin || !conn.cluster.Containers.ShellAccess.Admin {
  43                 if !conn.cluster.Containers.ShellAccess.User {
  44                         err = httpserver.ErrorWithStatus(errors.New("shell access is disabled in config"), http.StatusServiceUnavailable)
  45                         return
  46                 }
  47                 var crs arvados.ContainerRequestList
  48                 crs, err = conn.railsProxy.ContainerRequestList(ctxRoot, arvados.ListOptions{Limit: -1, Filters: []arvados.Filter{{"container_uuid", "=", opts.UUID}}})
  49                 if err != nil {
  50                         return
  51                 }
  52                 for _, cr := range crs.Items {
  53                         if cr.ModifiedByUserUUID != user.UUID {
  54                                 err = httpserver.ErrorWithStatus(errors.New("permission denied: container is associated with requests submitted by other users"), http.StatusForbidden)
  55                                 return
  56                         }
  57                 }
  58                 if crs.ItemsAvailable != len(crs.Items) {
  59                         err = httpserver.ErrorWithStatus(errors.New("incomplete response while checking permission"), http.StatusInternalServerError)
  60                         return
  61                 }
  62         }
  63
  64         switch ctr.State {
  65         case arvados.ContainerStateQueued, arvados.ContainerStateLocked:
  66                 err = httpserver.ErrorWithStatus(fmt.Errorf("gateway is not available, container is %s", strings.ToLower(string(ctr.State))), http.StatusServiceUnavailable)
  67                 return
  68         case arvados.ContainerStateRunning:
  69                 if ctr.GatewayAddress == "" {
  70                         err = httpserver.ErrorWithStatus(errors.New("container is running but gateway is not available"), http.StatusServiceUnavailable)
  71                         return
  72                 }
  73         default:
  74                 err = httpserver.ErrorWithStatus(fmt.Errorf("gateway is not available, container is %s", strings.ToLower(string(ctr.State))), http.StatusGone)
  75                 return
  76         }
  77         // crunch-run uses a self-signed / unverifiable TLS
  78         // certificate, so we use the following scheme to ensure we're
  79         // not talking to a MITM.
  80         //
  81         // 1. Compute ctrKey = HMAC-SHA256(sysRootToken,ctrUUID) --
  82         // this will be the same ctrKey that a-d-c supplied to
  83         // crunch-run in the GatewayAuthSecret env var.
  84         //
  85         // 2. Compute requestAuth = HMAC-SHA256(ctrKey,serverCert) and
  86         // send it to crunch-run as the X-Arvados-Authorization
  87         // header, proving that we know ctrKey. (Note a MITM cannot
  88         // replay the proof to a real crunch-run server, because the
  89         // real crunch-run server would have a different cert.)
  90         //
  91         // 3. Compute respondAuth = HMAC-SHA256(ctrKey,requestAuth)
  92         // and ensure the server returns it in the
  93         // X-Arvados-Authorization-Response header, proving that the
  94         // server knows ctrKey.
  95         var requestAuth, respondAuth string
  96         netconn, err := tls.Dial("tcp", ctr.GatewayAddress, &tls.Config{
  97                 InsecureSkipVerify: true,
  98                 VerifyPeerCertificate: func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error {
  99                         if len(rawCerts) == 0 {
 100                                 return errors.New("no certificate received, cannot compute authorization header")
 101                         }
 102                         h := hmac.New(sha256.New, []byte(conn.cluster.SystemRootToken))
 103                         fmt.Fprint(h, opts.UUID)
 104                         authKey := fmt.Sprintf("%x", h.Sum(nil))
 105                         h = hmac.New(sha256.New, []byte(authKey))
 106                         h.Write(rawCerts[0])
 107                         requestAuth = fmt.Sprintf("%x", h.Sum(nil))
 108                         h.Reset()
 109                         h.Write([]byte(requestAuth))
 110                         respondAuth = fmt.Sprintf("%x", h.Sum(nil))
 111                         return nil
 112                 },
 113         })
 114         if err != nil {
 115                 err = httpserver.ErrorWithStatus(err, http.StatusBadGateway)
 116                 return
 117         }
 118         if respondAuth == "" {
 119                 err = httpserver.ErrorWithStatus(errors.New("BUG: no respondAuth"), http.StatusInternalServerError)
 120                 return
 121         }
 122         bufr := bufio.NewReader(netconn)
 123         bufw := bufio.NewWriter(netconn)
 124
 125         u := url.URL{
 126                 Scheme: "http",
 127                 Host:   ctr.GatewayAddress,
 128                 Path:   "/ssh",
 129         }
 130         bufw.WriteString("GET " + u.String() + " HTTP/1.1\r\n")
 131         bufw.WriteString("Host: " + u.Host + "\r\n")
 132         bufw.WriteString("Upgrade: ssh\r\n")
 133         bufw.WriteString("X-Arvados-Target-Uuid: " + opts.UUID + "\r\n")
 134         bufw.WriteString("X-Arvados-Authorization: " + requestAuth + "\r\n")
 135         bufw.WriteString("X-Arvados-Detach-Keys: " + opts.DetachKeys + "\r\n")
 136         bufw.WriteString("X-Arvados-Login-Username: " + opts.LoginUsername + "\r\n")
 137         bufw.WriteString("\r\n")
 138         bufw.Flush()
 139         resp, err := http.ReadResponse(bufr, &http.Request{Method: "GET"})
 140         if err != nil {
 141                 err = httpserver.ErrorWithStatus(fmt.Errorf("error reading http response from gateway: %w", err), http.StatusBadGateway)
 142                 netconn.Close()
 143                 return
 144         }
 145         if resp.Header.Get("X-Arvados-Authorization-Response") != respondAuth {
 146                 err = httpserver.ErrorWithStatus(errors.New("bad X-Arvados-Authorization-Response header"), http.StatusBadGateway)
 147                 netconn.Close()
 148                 return
 149         }
 150         if strings.ToLower(resp.Header.Get("Upgrade")) != "ssh" ||
 151                 strings.ToLower(resp.Header.Get("Connection")) != "upgrade" {
 152                 err = httpserver.ErrorWithStatus(errors.New("bad upgrade"), http.StatusBadGateway)
 153                 netconn.Close()
 154                 return
 155         }
 156
 157         if !ctr.InteractiveSessionStarted {
 158                 _, err = conn.railsProxy.ContainerUpdate(ctxRoot, arvados.UpdateOptions{
 159                         UUID: opts.UUID,
 160                         Attrs: map[string]interface{}{
 161                                 "interactive_session_started": true,
 162                         },
 163                 })
 164                 if err != nil {
 165                         netconn.Close()
 166                         return
 167                 }
 168         }
 169
 170         sshconn.Conn = netconn
 171         sshconn.Bufrw = &bufio.ReadWriter{Reader: bufr, Writer: bufw}
 172         sshconn.Logger = ctxlog.FromContext(ctx)
 173         return
 174 }