[client] use embedded root CA if system certpool is empty (#3272)

* Implement custom TLS certificate handling with fallback to embedded roots

client/internal/auth/device_flow.go

@@ -2,6 +2,8 @@ package auth
 
 import (
 	"context"
+	"crypto/tls"
+	"crypto/x509"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -11,7 +13,10 @@ import (
 	"strings"
 	"time"
 
+	log "github.com/sirupsen/logrus"
+
 	"github.com/netbirdio/netbird/client/internal"
+	"github.com/netbirdio/netbird/util/embeddedroots"
 )
 
 // HostedGrantType grant type for device flow on Hosted
@@ -56,6 +61,18 @@ func NewDeviceAuthorizationFlow(config internal.DeviceAuthProviderConfig) (*Devi
 	httpTransport := http.DefaultTransport.(*http.Transport).Clone()
 	httpTransport.MaxIdleConns = 5
 
+	certPool, err := x509.SystemCertPool()
+	if err != nil || certPool == nil {
+		log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+		certPool = embeddedroots.Get()
+	} else {
+		log.Debug("Using system certificate pool.")
+	}
+
+	httpTransport.TLSClientConfig = &tls.Config{
+		RootCAs: certPool,
+	}
+
 	httpClient := &http.Client{
 		Timeout:   10 * time.Second,
 		Transport: httpTransport,

relay/client/dialer/ws/ws.go

@@ -2,6 +2,8 @@ package ws
 
 import (
 	"context"
+	"crypto/tls"
+	"crypto/x509"
 	"errors"
 	"fmt"
 	"net"
@@ -13,6 +15,7 @@ import (
 	"nhooyr.io/websocket"
 
 	"github.com/netbirdio/netbird/relay/server/listener/ws"
+	"github.com/netbirdio/netbird/util/embeddedroots"
 	nbnet "github.com/netbirdio/netbird/util/net"
 )
 
@@ -66,10 +69,19 @@ func prepareURL(address string) (string, error) {
 func httpClientNbDialer() *http.Client {
 	customDialer := nbnet.NewDialer()
 
+	certPool, err := x509.SystemCertPool()
+	if err != nil || certPool == nil {
+		log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+		certPool = embeddedroots.Get()
+	}
+
 	customTransport := &http.Transport{
 		DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
 			return customDialer.DialContext(ctx, network, addr)
 		},
+		TLSClientConfig: &tls.Config{
+			RootCAs: certPool,
+		},
 	}
 
 	return &http.Client{

relay/tls/client_dev.go

@@ -2,11 +2,25 @@
 
 package tls
 
-import "crypto/tls"
+import (
+	"crypto/tls"
+	"crypto/x509"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/util/embeddedroots"
+)
 
 func ClientQUICTLSConfig() *tls.Config {
+	certPool, err := x509.SystemCertPool()
+	if err != nil || certPool == nil {
+		log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+		certPool = embeddedroots.Get()
+	}
+
 	return &tls.Config{
 		InsecureSkipVerify: true,             // Debug mode allows insecure connections
 		NextProtos:         []string{nbalpn}, // Ensure this matches the server's ALPN
+		RootCAs:            certPool,
 	}
 }

relay/tls/client_prod.go

@@ -2,10 +2,24 @@
 
 package tls
 
-import "crypto/tls"
+import (
+	"crypto/tls"
+	"crypto/x509"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/util/embeddedroots"
+)
 
 func ClientQUICTLSConfig() *tls.Config {
+	certPool, err := x509.SystemCertPool()
+	if err != nil || certPool == nil {
+		log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+		certPool = embeddedroots.Get()
+	}
+
 	return &tls.Config{
 		NextProtos: []string{nbalpn},
+		RootCAs:    certPool,
 	}
 }

util/embeddedroots/embeddedroots.go

@@ -0,0 +1,42 @@
+package embeddedroots
+
+import (
+	"crypto/x509"
+	_ "embed"
+	"sync"
+)
+
+func Get() *x509.CertPool {
+	rootsVar.load()
+	return rootsVar.p
+}
+
+type roots struct {
+	once sync.Once
+	p    *x509.CertPool
+}
+
+var rootsVar roots
+
+func (r *roots) load() {
+	r.once.Do(func() {
+		p := x509.NewCertPool()
+		p.AppendCertsFromPEM([]byte(isrgRootX1RootPEM))
+		p.AppendCertsFromPEM([]byte(isrgRootX2RootPEM))
+		r.p = p
+	})
+}
+
+// Subject: O = Internet Security Research Group, CN = ISRG Root X1
+// Key type: RSA 4096
+// Validity: until 2030-06-04 (generated 2015-06-04)
+//
+//go:embed isrg-root-x1.pem
+var isrgRootX1RootPEM string
+
+// Subject: O = Internet Security Research Group, CN = ISRG Root X2
+// Key type: ECDSA P-384
+// Validity: until 2035-09-04 (generated 2020-09-04)
+//
+//go:embed isrg-root-x2.pem
+var isrgRootX2RootPEM string

util/embeddedroots/isrg-root-x1.pem

@@ -0,0 +1,31 @@
+-----BEGIN CERTIFICATE-----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=
+-----END CERTIFICATE-----

util/embeddedroots/isrg-root-x2.pem

@@ -0,0 +1,14 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

util/grpc/dialer.go

@@ -3,14 +3,16 @@ package grpc
 import (
 	"context"
 	"crypto/tls"
+	"crypto/x509"
 	"fmt"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 	"net"
 	"os/user"
 	"runtime"
 	"time"
 
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
 	"github.com/cenkalti/backoff/v4"
 	log "github.com/sirupsen/logrus"
 	"google.golang.org/grpc"
@@ -18,6 +20,7 @@ import (
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/keepalive"
 
+	"github.com/netbirdio/netbird/util/embeddedroots"
 	nbnet "github.com/netbirdio/netbird/util/net"
 )
 
@@ -57,9 +60,16 @@ func Backoff(ctx context.Context) backoff.BackOff {
 
 func CreateConnection(addr string, tlsEnabled bool) (*grpc.ClientConn, error) {
 	transportOption := grpc.WithTransportCredentials(insecure.NewCredentials())
-
 	if tlsEnabled {
-		transportOption = grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{}))
+		certPool, err := x509.SystemCertPool()
+		if err != nil || certPool == nil {
+			log.Debugf("System cert pool not available; falling back to embedded cert, error: %v", err)
+			certPool = embeddedroots.Get()
+		}
+
+		transportOption = grpc.WithTransportCredentials(credentials.NewTLS(&tls.Config{
+			RootCAs: certPool,
+		}))
 	}
 
 	connCtx, cancel := context.WithTimeout(context.Background(), 30*time.Second)