From e5900f493ce60b1f357b0511e3370dd381f4b4be Mon Sep 17 00:00:00 2001 From: bcmmbaga Date: Wed, 9 Sep 2026 18:21:52 +0300 Subject: [PATCH] Require a signed URL to write to the local --- upload-server/server/local.go | 41 +++++--- upload-server/server/local_test.go | 36 +++++-- upload-server/server/signing.go | 85 +++++++++++++++++ upload-server/server/signing_test.go | 136 +++++++++++++++++++++++++++ 4 files changed, 277 insertions(+), 21 deletions(-) create mode 100644 upload-server/server/signing.go create mode 100644 upload-server/server/signing_test.go diff --git a/upload-server/server/local.go b/upload-server/server/local.go index f7ca50011..c86da872b 100644 --- a/upload-server/server/local.go +++ b/upload-server/server/local.go @@ -8,6 +8,7 @@ import ( "os" "path/filepath" "strings" + "time" log "github.com/sirupsen/logrus" @@ -20,8 +21,9 @@ const ( ) type local struct { - url string - dir string + url string + dir string + signer *signer } func configureLocalHandlers(mux *http.ServeMux) error { @@ -44,9 +46,15 @@ func configureLocalHandlers(mux *http.ServeMux) error { dir = envDir } + uploadSigner, err := newSigner() + if err != nil { + return err + } + l := &local{ - url: envURL, - dir: dir, + url: envURL, + dir: dir, + signer: uploadSigner, } mux.HandleFunc(types.GetURLPath, l.handlerGetUploadURL) mux.HandleFunc(putURLPath+putHandler, l.handlePutRequest) @@ -80,6 +88,7 @@ func (l *local) getUploadURL(objectKey string) (string, error) { return "", fmt.Errorf("failed to parse upload URL: %w", err) } newURL := parsedUploadURL.JoinPath(parsedUploadURL.Path, putURLPath, objectKey) + newURL.RawQuery = l.signer.sign(objectKey, time.Now()).Encode() return newURL.String(), nil } @@ -91,13 +100,6 @@ func (l *local) handlePutRequest(w http.ResponseWriter, r *http.Request) { return } - r.Body = http.MaxBytesReader(w, r.Body, maxUploadSize) - body, err := io.ReadAll(r.Body) - if err != nil { - http.Error(w, "request body too large or failed to read", http.StatusRequestEntityTooLarge) - return - } - uploadDir := r.PathValue("dir") if uploadDir == "" { http.Error(w, "missing dir path", http.StatusBadRequest) @@ -109,6 +111,19 @@ func (l *local) handlePutRequest(w http.ResponseWriter, r *http.Request) { return } + if err := l.signer.verify(uploadDir+"/"+uploadFile, r.URL.Query(), time.Now()); err != nil { + http.Error(w, "unauthorized", http.StatusUnauthorized) + log.Warnf("Rejected upload of %s/%s: %v", uploadDir, uploadFile, err) + return + } + + r.Body = http.MaxBytesReader(w, r.Body, maxUploadSize) + body, err := io.ReadAll(r.Body) + if err != nil { + http.Error(w, "request body too large or failed to read", http.StatusRequestEntityTooLarge) + return + } + cleanBase := filepath.Clean(l.dir) + string(filepath.Separator) dirPath := filepath.Clean(filepath.Join(l.dir, uploadDir)) @@ -125,14 +140,14 @@ func (l *local) handlePutRequest(w http.ResponseWriter, r *http.Request) { return } - if err = os.MkdirAll(dirPath, 0750); err != nil { + if err = os.MkdirAll(dirPath, 0o750); err != nil { http.Error(w, "failed to create upload dir", http.StatusInternalServerError) log.Errorf("Failed to create upload dir: %v", err) return } flags := os.O_WRONLY | os.O_CREATE | os.O_EXCL - f, err := os.OpenFile(filePath, flags, 0600) + f, err := os.OpenFile(filePath, flags, 0o600) if err != nil { if os.IsExist(err) { http.Error(w, "file already exists", http.StatusConflict) diff --git a/upload-server/server/local_test.go b/upload-server/server/local_test.go index 64b8fd228..6681b8ec2 100644 --- a/upload-server/server/local_test.go +++ b/upload-server/server/local_test.go @@ -8,12 +8,21 @@ import ( "os" "path/filepath" "testing" + "time" "github.com/stretchr/testify/require" "github.com/netbirdio/netbird/upload-server/types" ) +const testSigningKey = "test-signing-key" + +func signedQuery(t *testing.T, objectKey string) string { + t.Helper() + s := &signer{key: []byte(testSigningKey)} + return s.sign(objectKey, time.Now()).Encode() +} + func Test_LocalHandlerGetUploadURL(t *testing.T) { mockURL := "http://localhost:8080" t.Setenv("SERVER_URL", mockURL) @@ -37,7 +46,6 @@ func Test_LocalHandlerGetUploadURL(t *testing.T) { require.Contains(t, response.URL, "test-file/") require.NotEmpty(t, response.Key) require.Contains(t, response.Key, "test-file/") - } func Test_LocalHandlePutRequest(t *testing.T) { @@ -45,13 +53,15 @@ func Test_LocalHandlePutRequest(t *testing.T) { mockURL := "http://localhost:8080" t.Setenv("SERVER_URL", mockURL) t.Setenv("STORE_DIR", mockDir) + t.Setenv(signingKeyVar, testSigningKey) mux := http.NewServeMux() err := configureLocalHandlers(mux) require.NoError(t, err) fileContent := []byte("test file content") - req := httptest.NewRequest(http.MethodPut, putURLPath+"/uploads/test.txt", bytes.NewReader(fileContent)) + req := httptest.NewRequest(http.MethodPut, + putURLPath+"/uploads/test.txt?"+signedQuery(t, "uploads/test.txt"), bytes.NewReader(fileContent)) rec := httptest.NewRecorder() mux.ServeHTTP(rec, req) @@ -69,13 +79,16 @@ func Test_LocalHandlePutRequest_PathTraversal(t *testing.T) { mockURL := "http://localhost:8080" t.Setenv("SERVER_URL", mockURL) t.Setenv("STORE_DIR", mockDir) + t.Setenv(signingKeyVar, testSigningKey) mux := http.NewServeMux() err := configureLocalHandlers(mux) require.NoError(t, err) fileContent := []byte("malicious content") - req := httptest.NewRequest(http.MethodPut, putURLPath+"/uploads/%2e%2e%2f%2e%2e%2fetc%2fpasswd", bytes.NewReader(fileContent)) + req := httptest.NewRequest(http.MethodPut, + putURLPath+"/uploads/%2e%2e%2f%2e%2e%2fetc%2fpasswd?"+signedQuery(t, "uploads/../../etc/passwd"), + bytes.NewReader(fileContent)) rec := httptest.NewRecorder() mux.ServeHTTP(rec, req) @@ -90,11 +103,13 @@ func Test_LocalHandlePutRequest_DirTraversal(t *testing.T) { mockDir := t.TempDir() t.Setenv("SERVER_URL", "http://localhost:8080") t.Setenv("STORE_DIR", mockDir) + t.Setenv(signingKeyVar, testSigningKey) - l := &local{url: "http://localhost:8080", dir: mockDir} + l := &local{url: "http://localhost:8080", dir: mockDir, signer: &signer{key: []byte(testSigningKey)}} body := bytes.NewReader([]byte("bad")) - req := httptest.NewRequest(http.MethodPut, putURLPath+"/x/evil.txt", body) + req := httptest.NewRequest(http.MethodPut, + putURLPath+"/x/evil.txt?"+signedQuery(t, "../../../tmp/evil.txt"), body) req.SetPathValue("dir", "../../../tmp") req.SetPathValue("file", "evil.txt") @@ -111,17 +126,20 @@ func Test_LocalHandlePutRequest_DuplicateFile(t *testing.T) { mockDir := t.TempDir() t.Setenv("SERVER_URL", "http://localhost:8080") t.Setenv("STORE_DIR", mockDir) + t.Setenv(signingKeyVar, testSigningKey) mux := http.NewServeMux() err := configureLocalHandlers(mux) require.NoError(t, err) - req := httptest.NewRequest(http.MethodPut, putURLPath+"/dir/dup.txt", bytes.NewReader([]byte("first"))) + req := httptest.NewRequest(http.MethodPut, + putURLPath+"/dir/dup.txt?"+signedQuery(t, "dir/dup.txt"), bytes.NewReader([]byte("first"))) rec := httptest.NewRecorder() mux.ServeHTTP(rec, req) require.Equal(t, http.StatusOK, rec.Code) - req = httptest.NewRequest(http.MethodPut, putURLPath+"/dir/dup.txt", bytes.NewReader([]byte("second"))) + req = httptest.NewRequest(http.MethodPut, + putURLPath+"/dir/dup.txt?"+signedQuery(t, "dir/dup.txt"), bytes.NewReader([]byte("second"))) rec = httptest.NewRecorder() mux.ServeHTTP(rec, req) require.Equal(t, http.StatusConflict, rec.Code) @@ -135,13 +153,15 @@ func Test_LocalHandlePutRequest_BodyTooLarge(t *testing.T) { mockDir := t.TempDir() t.Setenv("SERVER_URL", "http://localhost:8080") t.Setenv("STORE_DIR", mockDir) + t.Setenv(signingKeyVar, testSigningKey) mux := http.NewServeMux() err := configureLocalHandlers(mux) require.NoError(t, err) largeBody := make([]byte, maxUploadSize+1) - req := httptest.NewRequest(http.MethodPut, putURLPath+"/dir/big.txt", bytes.NewReader(largeBody)) + req := httptest.NewRequest(http.MethodPut, + putURLPath+"/dir/big.txt?"+signedQuery(t, "dir/big.txt"), bytes.NewReader(largeBody)) rec := httptest.NewRecorder() mux.ServeHTTP(rec, req) diff --git a/upload-server/server/signing.go b/upload-server/server/signing.go new file mode 100644 index 000000000..5d03b06b7 --- /dev/null +++ b/upload-server/server/signing.go @@ -0,0 +1,85 @@ +package server + +import ( + "crypto/hmac" + "crypto/rand" + "crypto/sha256" + "encoding/hex" + "fmt" + "net/url" + "os" + "strconv" + "time" + + log "github.com/sirupsen/logrus" +) + +const ( + signingKeyVar = "NB_UPLOAD_SIGNING_KEY" + + // signatureTTL matches the expiry the S3 backend puts on its presigned URLs. + signatureTTL = 15 * time.Minute + + expiryParam = "exp" + signatureParam = "sig" +) + +type signer struct { + key []byte +} + +func newSigner() (*signer, error) { + if env, ok := os.LookupEnv(signingKeyVar); ok { + if env == "" { + return nil, fmt.Errorf("%s is set but empty", signingKeyVar) + } + return &signer{key: []byte(env)}, nil + } + + key := make([]byte, 32) + if _, err := rand.Read(key); err != nil { + return nil, fmt.Errorf("generate signing key: %w", err) + } + log.Infof("%s not set, generated an ephemeral upload signing key", signingKeyVar) + + return &signer{key: key}, nil +} + +// sign returns the query parameters that authorize an upload of objectKey. +func (s *signer) sign(objectKey string, now time.Time) url.Values { + exp := now.Add(signatureTTL).Unix() + + v := url.Values{} + v.Set(expiryParam, strconv.FormatInt(exp, 10)) + v.Set(signatureParam, hex.EncodeToString(s.signature(objectKey, exp))) + + return v +} + +// verify reports whether query carries a still-valid signature over objectKey. +func (s *signer) verify(objectKey string, query url.Values, now time.Time) error { + exp, err := strconv.ParseInt(query.Get(expiryParam), 10, 64) + if err != nil { + return fmt.Errorf("malformed %s parameter", expiryParam) + } + + got, err := hex.DecodeString(query.Get(signatureParam)) + if err != nil { + return fmt.Errorf("malformed %s parameter", signatureParam) + } + + if !hmac.Equal(got, s.signature(objectKey, exp)) { + return fmt.Errorf("signature mismatch") + } + if now.Unix() > exp { + return fmt.Errorf("upload URL expired") + } + + return nil +} + +func (s *signer) signature(objectKey string, exp int64) []byte { + mac := hmac.New(sha256.New, s.key) + fmt.Fprintf(mac, "%s\n%d", objectKey, exp) + return mac.Sum(nil) +} diff --git a/upload-server/server/signing_test.go b/upload-server/server/signing_test.go new file mode 100644 index 000000000..a65eb468c --- /dev/null +++ b/upload-server/server/signing_test.go @@ -0,0 +1,136 @@ +package server + +import ( + "bytes" + "encoding/json" + "net/http" + "net/http/httptest" + "net/url" + "os" + "path/filepath" + "testing" + "time" + + "github.com/stretchr/testify/require" + + "github.com/netbirdio/netbird/upload-server/types" +) + +func newLocalMux(t *testing.T) (*http.ServeMux, string) { + t.Helper() + + mockDir := t.TempDir() + t.Setenv("SERVER_URL", "http://localhost:8080") + t.Setenv("STORE_DIR", mockDir) + t.Setenv(signingKeyVar, testSigningKey) + + mux := http.NewServeMux() + require.NoError(t, configureLocalHandlers(mux)) + + return mux, mockDir +} + +func Test_LocalUploadURLRoundTrip(t *testing.T) { + mux, mockDir := newLocalMux(t) + + getReq := httptest.NewRequest(http.MethodGet, types.GetURLPath+"?id=test-file", nil) + getReq.Header.Set(types.ClientHeader, types.ClientHeaderValue) + getRec := httptest.NewRecorder() + mux.ServeHTTP(getRec, getReq) + require.Equal(t, http.StatusOK, getRec.Code) + + var response types.GetURLResponse + require.NoError(t, json.Unmarshal(getRec.Body.Bytes(), &response)) + + minted, err := url.Parse(response.URL) + require.NoError(t, err) + require.NotEmpty(t, minted.Query().Get(signatureParam)) + + content := []byte("bundle") + putRec := httptest.NewRecorder() + mux.ServeHTTP(putRec, httptest.NewRequest(http.MethodPut, minted.RequestURI(), bytes.NewReader(content))) + require.Equal(t, http.StatusOK, putRec.Code) + + written, err := os.ReadFile(filepath.Join(mockDir, response.Key)) + require.NoError(t, err) + require.Equal(t, content, written) +} + +func Test_LocalHandlePutRequest_RejectsUnauthorized(t *testing.T) { + expired := &signer{key: []byte(testSigningKey)} + + tests := []struct { + name string + query string + }{ + { + name: "no signature", + query: "", + }, + { + name: "tampered signature", + query: "exp=99999999999&sig=deadbeef", + }, + { + name: "malformed signature", + query: "exp=99999999999&sig=not-hex", + }, + { + // A signature is only good for the key it was minted for, so a URL + // handed out for one bundle cannot be replayed against another. + name: "signature for a different object", + query: signedQuery(t, "dir/other.txt"), + }, + { + name: "expired signature", + query: expired.sign("dir/file.txt", time.Now().Add(-signatureTTL-time.Minute)).Encode(), + }, + } + + for _, tc := range tests { + t.Run(tc.name, func(t *testing.T) { + mux, mockDir := newLocalMux(t) + + target := putURLPath + "/dir/file.txt" + if tc.query != "" { + target += "?" + tc.query + } + + rec := httptest.NewRecorder() + mux.ServeHTTP(rec, httptest.NewRequest(http.MethodPut, target, bytes.NewReader([]byte("payload")))) + + require.Equal(t, http.StatusUnauthorized, rec.Code) + + _, err := os.Stat(filepath.Join(mockDir, "dir", "file.txt")) + require.True(t, os.IsNotExist(err), "unauthorized upload should not be written") + }) + } +} + +func Test_SignerRejectsForeignKey(t *testing.T) { + minted := (&signer{key: []byte("one key")}).sign("dir/file.txt", time.Now()) + + err := (&signer{key: []byte("another key")}).verify("dir/file.txt", minted, time.Now()) + require.Error(t, err) +} + +func Test_NewSignerGeneratesEphemeralKey(t *testing.T) { + // Registers the restore hook, then clears the value for this test only. + t.Setenv(signingKeyVar, "") + os.Unsetenv(signingKeyVar) + + first, err := newSigner() + require.NoError(t, err) + second, err := newSigner() + require.NoError(t, err) + + require.NotEqual(t, first.key, second.key) + require.Len(t, first.key, 32) +} + +func Test_NewSignerRejectsEmptyKey(t *testing.T) { + t.Setenv(signingKeyVar, "") + + _, err := newSigner() + require.Error(t, err) +}