headscale/oidc.go
Kristoffer Dalby 469551bc5d Register new machines needing callback in memory
This commit stores temporary registration data in cache, instead of
memory allowing us to only have actually registered machines in the
database.
2022-02-28 08:06:39 +00:00

368 lines
8.8 KiB
Go

package headscale
import (
"bytes"
"context"
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"html/template"
"net/http"
"strings"
"time"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/gin-gonic/gin"
"github.com/patrickmn/go-cache"
"github.com/rs/zerolog/log"
"golang.org/x/oauth2"
"gorm.io/gorm"
"tailscale.com/types/key"
)
const (
oidcStateCacheExpiration = time.Minute * 5
oidcStateCacheCleanupInterval = time.Minute * 10
randomByteSize = 16
)
type IDTokenClaims struct {
Name string `json:"name,omitempty"`
Groups []string `json:"groups,omitempty"`
Email string `json:"email"`
Username string `json:"preferred_username,omitempty"`
}
func (h *Headscale) initOIDC() error {
var err error
// grab oidc config if it hasn't been already
if h.oauth2Config == nil {
h.oidcProvider, err = oidc.NewProvider(context.Background(), h.cfg.OIDC.Issuer)
if err != nil {
log.Error().
Err(err).
Caller().
Msgf("Could not retrieve OIDC Config: %s", err.Error())
return err
}
h.oauth2Config = &oauth2.Config{
ClientID: h.cfg.OIDC.ClientID,
ClientSecret: h.cfg.OIDC.ClientSecret,
Endpoint: h.oidcProvider.Endpoint(),
RedirectURL: fmt.Sprintf(
"%s/oidc/callback",
strings.TrimSuffix(h.cfg.ServerURL, "/"),
),
Scopes: []string{oidc.ScopeOpenID, "profile", "email"},
}
}
// init the state cache if it hasn't been already
if h.oidcStateCache == nil {
h.oidcStateCache = cache.New(
oidcStateCacheExpiration,
oidcStateCacheCleanupInterval,
)
}
return nil
}
// RegisterOIDC redirects to the OIDC provider for authentication
// Puts machine key in cache so the callback can retrieve it using the oidc state param
// Listens in /oidc/register/:mKey.
func (h *Headscale) RegisterOIDC(ctx *gin.Context) {
machineKeyStr := ctx.Param("mkey")
if machineKeyStr == "" {
ctx.String(http.StatusBadRequest, "Wrong params")
return
}
log.Trace().
Caller().
Str("machine_key", machineKeyStr).
Msg("Received oidc register call")
randomBlob := make([]byte, randomByteSize)
if _, err := rand.Read(randomBlob); err != nil {
log.Error().
Caller().
Msg("could not read 16 bytes from rand")
ctx.String(http.StatusInternalServerError, "could not read 16 bytes from rand")
return
}
stateStr := hex.EncodeToString(randomBlob)[:32]
// place the machine key into the state cache, so it can be retrieved later
h.oidcStateCache.Set(stateStr, machineKeyStr, oidcStateCacheExpiration)
authURL := h.oauth2Config.AuthCodeURL(stateStr)
log.Debug().Msgf("Redirecting to %s for authentication", authURL)
ctx.Redirect(http.StatusFound, authURL)
}
type oidcCallbackTemplateConfig struct {
User string
Verb string
}
var oidcCallbackTemplate = template.Must(
template.New("oidccallback").Parse(`<html>
<body>
<h1>headscale</h1>
<p>
{{.Verb}} as {{.User}}, you can now close this window.
</p>
</body>
</html>`),
)
// TODO: Why is the entire machine registration logic duplicated here?
// OIDCCallback handles the callback from the OIDC endpoint
// Retrieves the mkey from the state cache and adds the machine to the users email namespace
// TODO: A confirmation page for new machines should be added to avoid phishing vulnerabilities
// TODO: Add groups information from OIDC tokens into machine HostInfo
// Listens in /oidc/callback.
func (h *Headscale) OIDCCallback(ctx *gin.Context) {
code := ctx.Query("code")
state := ctx.Query("state")
if code == "" || state == "" {
ctx.String(http.StatusBadRequest, "Wrong params")
return
}
oauth2Token, err := h.oauth2Config.Exchange(context.Background(), code)
if err != nil {
ctx.String(http.StatusBadRequest, "Could not exchange code for token")
return
}
log.Trace().
Caller().
Str("code", code).
Str("state", state).
Msg("Got oidc callback")
rawIDToken, rawIDTokenOK := oauth2Token.Extra("id_token").(string)
if !rawIDTokenOK {
ctx.String(http.StatusBadRequest, "Could not extract ID Token")
return
}
verifier := h.oidcProvider.Verifier(&oidc.Config{ClientID: h.cfg.OIDC.ClientID})
idToken, err := verifier.Verify(context.Background(), rawIDToken)
if err != nil {
log.Error().
Err(err).
Caller().
Msg("failed to verify id token")
ctx.String(http.StatusBadRequest, "Failed to verify id token")
return
}
// TODO: we can use userinfo at some point to grab additional information about the user (groups membership, etc)
// userInfo, err := oidcProvider.UserInfo(context.Background(), oauth2.StaticTokenSource(oauth2Token))
// if err != nil {
// c.String(http.StatusBadRequest, fmt.Sprintf("Failed to retrieve userinfo"))
// return
// }
// Extract custom claims
var claims IDTokenClaims
if err = idToken.Claims(&claims); err != nil {
log.Error().
Err(err).
Caller().
Msg("Failed to decode id token claims")
ctx.String(
http.StatusBadRequest,
"Failed to decode id token claims",
)
return
}
// retrieve machinekey from state cache
machineKeyIf, machineKeyFound := h.oidcStateCache.Get(state)
if !machineKeyFound {
log.Error().
Msg("requested machine state key expired before authorisation completed")
ctx.String(http.StatusBadRequest, "state has expired")
return
}
machineKeyStr, machineKeyOK := machineKeyIf.(string)
var machineKey key.MachinePublic
err = machineKey.UnmarshalText([]byte(MachinePublicKeyEnsurePrefix(machineKeyStr)))
if err != nil {
log.Error().
Msg("could not parse machine public key")
ctx.String(http.StatusBadRequest, "could not parse public key")
return
}
if !machineKeyOK {
log.Error().Msg("could not get machine key from cache")
ctx.String(
http.StatusInternalServerError,
"could not get machine key from cache",
)
return
}
// TODO(kradalby): Currently, if it fails to find a requested expiry, non will be set
requestedTime := time.Time{}
if requestedTimeIf, found := h.requestedExpiryCache.Get(machineKey.String()); found {
if reqTime, ok := requestedTimeIf.(time.Time); ok {
requestedTime = reqTime
}
}
// retrieve machine information
machine, err := h.GetMachineByMachineKey(machineKey)
if err != nil {
log.Error().Msg("machine key not found in database")
ctx.String(
http.StatusInternalServerError,
"could not get machine info from database",
)
return
}
if machine.isRegistered() {
log.Trace().
Caller().
Str("machine", machine.Name).
Msg("machine already registered, reauthenticating")
h.RefreshMachine(machine, requestedTime)
var content bytes.Buffer
if err := oidcCallbackTemplate.Execute(&content, oidcCallbackTemplateConfig{
User: claims.Email,
Verb: "Reauthenticated",
}); err != nil {
log.Error().
Str("func", "OIDCCallback").
Str("type", "reauthenticate").
Err(err).
Msg("Could not render OIDC callback template")
ctx.Data(
http.StatusInternalServerError,
"text/html; charset=utf-8",
[]byte("Could not render OIDC callback template"),
)
}
ctx.Data(http.StatusOK, "text/html; charset=utf-8", content.Bytes())
return
}
namespaceName, err := NormalizeNamespaceName(
claims.Email,
h.cfg.OIDC.StripEmaildomain,
)
if err != nil {
log.Error().Err(err).Caller().Msgf("couldn't normalize email")
ctx.String(
http.StatusInternalServerError,
"couldn't normalize email",
)
return
}
// register the machine if it's new
if !machine.Registered {
log.Debug().Msg("Registering new machine after successful callback")
namespace, err := h.GetNamespace(namespaceName)
if errors.Is(err, gorm.ErrRecordNotFound) {
namespace, err = h.CreateNamespace(namespaceName)
if err != nil {
log.Error().
Err(err).
Caller().
Msgf("could not create new namespace '%s'", namespaceName)
ctx.String(
http.StatusInternalServerError,
"could not create new namespace",
)
return
}
} else if err != nil {
log.Error().
Caller().
Err(err).
Str("namespace", namespaceName).
Msg("could not find or create namespace")
ctx.String(
http.StatusInternalServerError,
"could not find or create namespace",
)
return
}
_, err = h.RegisterMachineFromAuthCallback(
machineKeyStr,
namespace.Name,
RegisterMethodOIDC,
&requestedTime,
)
if err != nil {
log.Error().
Caller().
Err(err).
Msg("could not register machine")
ctx.String(
http.StatusInternalServerError,
"could not register machine",
)
return
}
}
var content bytes.Buffer
if err := oidcCallbackTemplate.Execute(&content, oidcCallbackTemplateConfig{
User: claims.Email,
Verb: "Authenticated",
}); err != nil {
log.Error().
Str("func", "OIDCCallback").
Str("type", "authenticate").
Err(err).
Msg("Could not render OIDC callback template")
ctx.Data(
http.StatusInternalServerError,
"text/html; charset=utf-8",
[]byte("Could not render OIDC callback template"),
)
}
ctx.Data(http.StatusOK, "text/html; charset=utf-8", content.Bytes())
}