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token_provider.go
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/
token_provider.go
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package aztokenprovider
import (
"context"
"errors"
"fmt"
"net/http"
"github.com/golang-jwt/jwt/v5"
"github.com/grafana/grafana-azure-sdk-go/v2/azcredentials"
"github.com/grafana/grafana-azure-sdk-go/v2/azsettings"
"github.com/grafana/grafana-azure-sdk-go/v2/azusercontext"
"github.com/grafana/grafana-plugin-sdk-go/backend"
)
var (
azureTokenCache = NewConcurrentTokenCache()
)
type AzureTokenProvider interface {
GetAccessToken(ctx context.Context, scopes []string) (string, error)
}
func NewAzureAccessTokenProvider(settings *azsettings.AzureSettings, credentials azcredentials.AzureCredentials,
userIdentitySupported bool) (AzureTokenProvider, error) {
var err error
if settings == nil {
err = fmt.Errorf("parameter 'settings' cannot be nil")
return nil, err
}
if credentials == nil {
err = fmt.Errorf("parameter 'credentials' cannot be nil")
return nil, err
}
switch c := credentials.(type) {
case *azcredentials.AzureManagedIdentityCredentials:
if !settings.ManagedIdentityEnabled {
err = fmt.Errorf("managed identity authentication is not enabled in Grafana config")
return nil, err
}
tokenRetriever := getManagedIdentityTokenRetriever(settings, c)
return &serviceTokenProvider{
tokenCache: azureTokenCache,
tokenRetriever: tokenRetriever,
}, nil
case *azcredentials.AzureWorkloadIdentityCredentials:
if !settings.WorkloadIdentityEnabled {
err = fmt.Errorf("workload identity authentication is not enabled in Grafana config")
return nil, err
}
tokenRetriever := getWorkloadIdentityTokenRetriever(settings, c)
return &serviceTokenProvider{
tokenCache: azureTokenCache,
tokenRetriever: tokenRetriever,
}, nil
case *azcredentials.AzureClientSecretCredentials:
tokenRetriever, err := getClientSecretTokenRetriever(settings, c)
if err != nil {
return nil, err
}
return &serviceTokenProvider{
tokenCache: azureTokenCache,
tokenRetriever: tokenRetriever,
}, nil
case *azcredentials.AadCurrentUserCredentials:
if !userIdentitySupported {
err = fmt.Errorf("user identity authentication is not supported by this datasource")
return nil, err
}
if !settings.UserIdentityEnabled {
err = fmt.Errorf("user identity authentication is not enabled in Grafana config")
return nil, err
}
var tokenRetriever TokenRetriever
if c.ServiceCredentialsEnabled && c.ServiceCredentials != nil && settings.UserIdentityFallbackCredentialsEnabled {
fallbackType := c.ServiceCredentials.AzureAuthType()
if fallbackType == azcredentials.AzureAuthCurrentUserIdentity || fallbackType == azcredentials.AzureAuthClientSecretObo {
return nil, fmt.Errorf("user identity authentication not valid for fallback credentials")
}
switch c.ServiceCredentials.(type) {
case *azcredentials.AzureClientSecretCredentials:
tokenRetriever, err = getClientSecretTokenRetriever(settings, c.ServiceCredentials.(*azcredentials.AzureClientSecretCredentials))
if err != nil {
return nil, err
}
case *azcredentials.AzureManagedIdentityCredentials:
tokenRetriever = getManagedIdentityTokenRetriever(settings, c.ServiceCredentials.(*azcredentials.AzureManagedIdentityCredentials))
case *azcredentials.AzureWorkloadIdentityCredentials:
tokenRetriever = getWorkloadIdentityTokenRetriever(settings, c.ServiceCredentials.(*azcredentials.AzureWorkloadIdentityCredentials))
}
}
tokenEndpoint := settings.UserIdentityTokenEndpoint
client, err := NewTokenClient(tokenEndpoint.TokenUrl, tokenEndpoint.ClientId, tokenEndpoint.ClientSecret, http.DefaultClient)
if err != nil {
err = fmt.Errorf("failed to initialize user authentication provider: %w", err)
return nil, err
}
return &userTokenProvider{
tokenCache: azureTokenCache,
client: client,
usernameAssertion: tokenEndpoint.UsernameAssertion,
tokenRetriever: tokenRetriever,
}, nil
default:
err = fmt.Errorf("credentials of type '%s' not supported by Azure authentication provider", c.AzureAuthType())
return nil, err
}
}
type serviceTokenProvider struct {
tokenCache ConcurrentTokenCache
tokenRetriever TokenRetriever
}
func (provider *serviceTokenProvider) GetAccessToken(ctx context.Context, scopes []string) (string, error) {
if ctx == nil {
err := fmt.Errorf("parameter 'ctx' cannot be nil")
return "", err
}
if scopes == nil {
err := fmt.Errorf("parameter 'scopes' cannot be nil")
return "", err
}
accessToken, err := provider.tokenCache.GetAccessToken(ctx, provider.tokenRetriever, scopes)
if err != nil {
return "", err
}
return accessToken, nil
}
type userTokenProvider struct {
tokenCache ConcurrentTokenCache
client TokenClient
usernameAssertion bool
tokenRetriever TokenRetriever
}
func isAzureUser(currentUser azusercontext.CurrentUserContext) (azusercontext.CurrentUserContext, error) {
// This should always be present for logged in users. idForwarding feature toggle must be enabled. By default we return true if there's no ID token available
if currentUser.GrafanaIdToken != "" {
claims := jwt.MapClaims{}
_, _, err := jwt.NewParser(jwt.WithValidMethods([]string{"ES256"})).ParseUnverified(currentUser.GrafanaIdToken, claims)
if err != nil {
return currentUser, fmt.Errorf("failed to decode user jwt: %s", err)
}
if claims["authenticatedBy"] != "oauth_azuread" {
return currentUser, fmt.Errorf("user is not authenticated with Azure AD")
}
return currentUser, nil
}
return currentUser, nil
}
func isBackendRequest(currentUser azusercontext.CurrentUserContext, idForwardingEnabled bool) bool {
// If the User struct is nil or there is no ID token then it's a backend initiated request
if currentUser.User == nil {
return true
}
// If ID forwarding is enabled we can assume this is backend initiated when empty
if currentUser.GrafanaIdToken == "" && idForwardingEnabled {
return true
}
return false
}
func (provider *userTokenProvider) GetAccessToken(ctx context.Context, scopes []string) (string, error) {
if ctx == nil {
err := fmt.Errorf("parameter 'ctx' cannot be nil")
return "", err
}
if scopes == nil {
err := fmt.Errorf("parameter 'scopes' cannot be nil")
return "", err
}
settings, err := azsettings.ReadSettings(ctx)
if err != nil {
err := fmt.Errorf("error reading azure settings: %s", err)
return "", err
}
currentUser, ok := azusercontext.GetCurrentUser(ctx)
if !ok {
return "", fmt.Errorf("user context not configured")
}
idForwardingSupported := backend.GrafanaConfigFromContext(ctx).FeatureToggles().IsEnabled("idForwarding")
backendRequest := isBackendRequest(currentUser, idForwardingSupported)
if backendRequest {
// Use fallback credentials if this is a backend request and fallback credentials are enabled
if settings.UserIdentityFallbackCredentialsEnabled && !provider.usernameAssertion {
if provider.tokenRetriever != nil {
accessToken, err := provider.tokenCache.GetAccessToken(ctx, provider.tokenRetriever, scopes)
if err != nil {
return "", err
}
return accessToken, nil
}
}
return "", fmt.Errorf("fallback credentials not enabled")
}
azureUser, err := isAzureUser(currentUser)
if err != nil {
return "", err
}
username, err := extractUsername(azureUser)
if err != nil {
err := fmt.Errorf("user identity authentication only possible in context of a Grafana user: %w", err)
return "", err
}
var tokenRetriever TokenRetriever
if provider.usernameAssertion {
tokenRetriever = &usernameTokenRetriever{
client: provider.client,
username: username,
}
} else {
idToken := azureUser.IdToken
if idToken == "" {
err := fmt.Errorf("user identity authentication not possible because there's no ID token associated with the Grafana user")
return "", err
}
tokenRetriever = &onBehalfOfTokenRetriever{
client: provider.client,
userId: username,
idToken: idToken,
}
}
accessToken, err := provider.tokenCache.GetAccessToken(ctx, tokenRetriever, scopes)
if err != nil {
err = fmt.Errorf("unable to acquire access token for user '%s': %w", username, err)
return "", err
}
return accessToken, nil
}
func extractUsername(userCtx azusercontext.CurrentUserContext) (string, error) {
user := userCtx.User
if user != nil && user.Login != "" {
return user.Login, nil
} else {
return "", errors.New("request not associated with a Grafana user")
}
}