headscale/oidc.go
Kristoffer Dalby cfd53bc4aa Factor wgkey to types/key
This commit converts all the uses of wgkey to the new key interfaces.

It now has specific  machine, node and discovery keys and we now should
use them correctly.

Please note the new logic which strips a key prefix (in utils.go) that
is now standard inside tailscale.

In theory we could put it in the database, but to preserve backwards
compatibility and not spend a lot of resources on accounting for both,
we just strip them.
2021-11-26 23:30:42 +00:00

358 lines
8.7 KiB
Go

package headscale
import (
"context"
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"net/http"
"regexp"
"strings"
"time"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/gin-gonic/gin"
"github.com/patrickmn/go-cache"
"github.com/rs/zerolog/log"
"go4.org/mem"
"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)
}
// 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)
machineKey, err := key.ParseMachinePublicUntyped(mem.S(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)
ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(fmt.Sprintf(`
<html>
<body>
<h1>headscale</h1>
<p>
Reuthenticated as %s, you can now close this window.
</p>
</body>
</html>
`, claims.Email)))
return
}
now := time.Now().UTC()
if namespaceName, ok := h.getNamespaceFromEmail(claims.Email); ok {
// 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
}
ip, err := h.getAvailableIP()
if err != nil {
log.Error().
Caller().
Err(err).
Msg("could not get an IP from the pool")
ctx.String(
http.StatusInternalServerError,
"could not get an IP from the pool",
)
return
}
machine.IPAddress = ip.String()
machine.NamespaceID = namespace.ID
machine.Registered = true
machine.RegisterMethod = RegisterMethodOIDC
machine.LastSuccessfulUpdate = &now
machine.Expiry = &requestedTime
h.db.Save(&machine)
}
ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(fmt.Sprintf(`
<html>
<body>
<h1>headscale</h1>
<p>
Authenticated as %s, you can now close this window.
</p>
</body>
</html>
`, claims.Email)))
return
}
log.Error().
Caller().
Str("email", claims.Email).
Str("username", claims.Username).
Str("machine", machine.Name).
Msg("Email could not be mapped to a namespace")
ctx.String(
http.StatusBadRequest,
"email from claim could not be mapped to a namespace",
)
}
// getNamespaceFromEmail passes the users email through a list of "matchers"
// and iterates through them until it matches and returns a namespace.
// If no match is found, an empty string will be returned.
// TODO(kradalby): golang Maps key order is not stable, so this list is _not_ deterministic. Find a way to make the list of keys stable, preferably in the order presented in a users configuration.
func (h *Headscale) getNamespaceFromEmail(email string) (string, bool) {
for match, namespace := range h.cfg.OIDC.MatchMap {
regex := regexp.MustCompile(match)
if regex.MatchString(email) {
return namespace, true
}
}
return "", false
}