web: Validate if bucket names are reserved (#3841)

Both '.minio.sys' and 'minio' should be never allowed
to be created from web-ui and then fail to list it
by filtering them out.

Fixes #3840

cmd/generic-handlers.go

@@ -20,7 +20,6 @@ import (
 	"bufio"
 	"net"
 	"net/http"
-	"path"
 	"strings"
 	"time"
 
@@ -161,17 +160,17 @@ func (h cacheControlHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 // Adds verification for incoming paths.
 type minioPrivateBucketHandler struct {
-	handler            http.Handler
-	reservedBucketPath string
+	handler http.Handler
 }
 
 func setPrivateBucketHandler(h http.Handler) http.Handler {
-	return minioPrivateBucketHandler{h, minioReservedBucketPath}
+	return minioPrivateBucketHandler{h}
 }
 
 func (h minioPrivateBucketHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	// For all non browser requests, reject access to 'reservedBucketPath'.
-	if !guessIsBrowserReq(r) && path.Clean(r.URL.Path) == h.reservedBucketPath {
+	// For all non browser requests, reject access to 'minioReservedBucketPath'.
+	bucketName, _ := urlPath2BucketObjectName(r.URL)
+	if !guessIsBrowserReq(r) && isMinioReservedBucket(bucketName) && isMinioMetaBucket(bucketName) {
 		writeErrorResponse(w, ErrAllAccessDisabled, r.URL)
 		return
 	}

cmd/object-api-utils.go

@@ -194,7 +194,17 @@ func isReservedOrInvalidBucket(bucketEntry string) bool {
 	if !IsValidBucketName(bucketEntry) {
 		return true
 	}
-	return bucketEntry == minioMetaBucket || bucketEntry == minioReservedBucket
+	return isMinioMetaBucket(bucketEntry) || isMinioReservedBucket(bucketEntry)
+}
+
+// Returns true if input bucket is a reserved minio meta bucket '.minio.sys'.
+func isMinioMetaBucket(bucketName string) bool {
+	return bucketName == minioMetaBucket
+}
+
+// Returns true if input bucket is a reserved minio bucket 'minio'.
+func isMinioReservedBucket(bucketName string) bool {
+	return bucketName == minioReservedBucket
 }
 
 // byBucketName is a collection satisfying sort.Interface.

cmd/typed-errors.go

@@ -50,3 +50,7 @@ var errServerVersionMismatch = errors.New("Server versions do not match")
 
 // errServerTimeMismatch - server times are too far apart.
 var errServerTimeMismatch = errors.New("Server times are too far apart")
+
+// errReservedBucket - bucket name is reserved for Minio, usually
+// returned for 'minio', '.minio.sys'
+var errReservedBucket = errors.New("All access to this bucket is disabled")

cmd/web-handlers.go

@@ -113,7 +113,7 @@ type MakeBucketArgs struct {
 	BucketName string `json:"bucketName"`
 }
 
-// MakeBucket - make a bucket.
+// MakeBucket - creates a new bucket.
 func (web *webAPIHandlers) MakeBucket(r *http.Request, args *MakeBucketArgs, reply *WebGenericRep) error {
 	objectAPI := web.ObjectAPI()
 	if objectAPI == nil {
@@ -122,12 +122,19 @@ func (web *webAPIHandlers) MakeBucket(r *http.Request, args *MakeBucketArgs, rep
 	if !isHTTPRequestValid(r) {
 		return toJSONError(errAuthentication)
 	}
+
+	// Check if bucket is a reserved bucket name.
+	if isMinioMetaBucket(args.BucketName) || isMinioReservedBucket(args.BucketName) {
+		return toJSONError(errReservedBucket)
+	}
+
 	bucketLock := globalNSMutex.NewNSLock(args.BucketName, "")
 	bucketLock.Lock()
 	defer bucketLock.Unlock()
 	if err := objectAPI.MakeBucket(args.BucketName); err != nil {
 		return toJSONError(err, args.BucketName)
 	}
+
 	reply.UIVersion = browser.UIVersion
 	return nil
 }
@@ -890,6 +897,13 @@ func toJSONError(err error, params ...string) (jerr *json2.Error) {
 		Message: apiErr.Description,
 	}
 	switch apiErr.Code {
+	// Reserved bucket name provided.
+	case "AllAccessDisabled":
+		if len(params) > 0 {
+			jerr = &json2.Error{
+				Message: fmt.Sprintf("All access to this bucket %s has been disabled.", params[0]),
+			}
+		}
 	// Bucket name invalid with custom error message.
 	case "InvalidBucketName":
 		if len(params) > 0 {
@@ -961,6 +975,12 @@ func toWebAPIError(err error) APIError {
 			HTTPStatusCode: http.StatusMethodNotAllowed,
 			Description:    err.Error(),
 		}
+	} else if err == errReservedBucket {
+		return APIError{
+			Code:           "AllAccessDisabled",
+			HTTPStatusCode: http.StatusForbidden,
+			Description:    err.Error(),
+		}
 	}
 	// Convert error type to api error code.
 	var apiErrCode APIErrorCode

cmd/web-handlers_test.go

@@ -265,6 +265,8 @@ func testMakeBucketWebHandler(obj ObjectLayer, instanceType string, t TestErrHan
 		{"", false},
 		{".", false},
 		{"ab", false},
+		{"minio", false},
+		{".minio.sys", false},
 		{bucketName, true},
 	}