diff --git a/staticlibs/device/com/android/net/module/util/BpfMap.java b/staticlibs/device/com/android/net/module/util/BpfMap.java
index 2267f31..9042085 100644
--- a/staticlibs/device/com/android/net/module/util/BpfMap.java
+++ b/staticlibs/device/com/android/net/module/util/BpfMap.java
@@ -67,8 +67,10 @@
     private static ConcurrentHashMap<Pair<String, Integer>, ParcelFileDescriptor> sFdCache =
             new ConcurrentHashMap<>();
 
-    private static ParcelFileDescriptor cachedBpfFdGet(String path, int mode)
+    private static ParcelFileDescriptor cachedBpfFdGet(String path, int mode,
+                                                       int keySize, int valueSize)
             throws ErrnoException, NullPointerException {
+        // TODO: key should include keySize & valueSize, but really we should match specific types
         Pair<String, Integer> key = Pair.create(path, mode);
         // unlocked fetch is safe: map is concurrent read capable, and only inserted into
         ParcelFileDescriptor fd = sFdCache.get(key);
@@ -79,7 +81,7 @@
             fd = sFdCache.get(key);
             if (fd != null) return fd;
             // okay, we really haven't opened this before...
-            fd = ParcelFileDescriptor.adoptFd(nativeBpfFdGet(path, mode));
+            fd = ParcelFileDescriptor.adoptFd(nativeBpfFdGet(path, mode, keySize, valueSize));
             sFdCache.put(key, fd);
             return fd;
         }
@@ -94,11 +96,11 @@
      */
     public BpfMap(@NonNull final String path, final int flag, final Class<K> key,
             final Class<V> value) throws ErrnoException, NullPointerException {
-        mMapFd = cachedBpfFdGet(path, flag);
         mKeyClass = key;
         mValueClass = value;
         mKeySize = Struct.getSize(key);
         mValueSize = Struct.getSize(value);
+        mMapFd = cachedBpfFdGet(path, flag, mKeySize, mValueSize);
     }
 
     /**
@@ -295,7 +297,7 @@
         }
     }
 
-    private static native int nativeBpfFdGet(String path, int mode)
+    private static native int nativeBpfFdGet(String path, int mode, int keySize, int valueSize)
             throws ErrnoException, NullPointerException;
 
     // Note: the following methods appear to not require the object by virtue of taking the
diff --git a/staticlibs/native/bpf_headers/include/bpf/BpfUtils.h b/staticlibs/native/bpf_headers/include/bpf/BpfUtils.h
index 28d4b8b..e2cb676 100644
--- a/staticlibs/native/bpf_headers/include/bpf/BpfUtils.h
+++ b/staticlibs/native/bpf_headers/include/bpf/BpfUtils.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <errno.h>
 #include <linux/if_ether.h>
 #include <linux/pfkeyv2.h>
 #include <net/if.h>
@@ -25,9 +26,10 @@
 #include <sys/socket.h>
 #include <sys/utsname.h>
 
-#include <android-base/unique_fd.h>
 #include <log/log.h>
 
+#include "KernelVersion.h"
+
 namespace android {
 namespace bpf {
 
@@ -84,27 +86,5 @@
     return res;
 }
 
-#define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c))
-
-static inline unsigned uncachedKernelVersion() {
-    struct utsname buf;
-    if (uname(&buf)) return 0;
-
-    unsigned kver_major = 0;
-    unsigned kver_minor = 0;
-    unsigned kver_sub = 0;
-    (void)sscanf(buf.release, "%u.%u.%u", &kver_major, &kver_minor, &kver_sub);
-    return KVER(kver_major, kver_minor, kver_sub);
-}
-
-static inline unsigned kernelVersion() {
-    static unsigned kver = uncachedKernelVersion();
-    return kver;
-}
-
-static inline bool isAtLeastKernelVersion(unsigned major, unsigned minor, unsigned sub) {
-    return kernelVersion() >= KVER(major, minor, sub);
-}
-
 }  // namespace bpf
 }  // namespace android
diff --git a/staticlibs/native/bpf_headers/include/bpf/KernelVersion.h b/staticlibs/native/bpf_headers/include/bpf/KernelVersion.h
new file mode 100644
index 0000000..e0e53a9
--- /dev/null
+++ b/staticlibs/native/bpf_headers/include/bpf/KernelVersion.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/utsname.h>
+
+namespace android {
+namespace bpf {
+
+#define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c))
+
+static inline unsigned uncachedKernelVersion() {
+    struct utsname buf;
+    if (uname(&buf)) return 0;
+
+    unsigned kver_major = 0;
+    unsigned kver_minor = 0;
+    unsigned kver_sub = 0;
+    (void)sscanf(buf.release, "%u.%u.%u", &kver_major, &kver_minor, &kver_sub);
+    return KVER(kver_major, kver_minor, kver_sub);
+}
+
+static inline unsigned kernelVersion() {
+    static unsigned kver = uncachedKernelVersion();
+    return kver;
+}
+
+static inline bool isAtLeastKernelVersion(unsigned major, unsigned minor, unsigned sub) {
+    return kernelVersion() >= KVER(major, minor, sub);
+}
+
+}  // namespace bpf
+}  // namespace android
diff --git a/staticlibs/native/bpfmapjni/Android.bp b/staticlibs/native/bpfmapjni/Android.bp
index cd254d4..8babcce 100644
--- a/staticlibs/native/bpfmapjni/Android.bp
+++ b/staticlibs/native/bpfmapjni/Android.bp
@@ -23,7 +23,7 @@
         "com_android_net_module_util_TcUtils.cpp",
     ],
     header_libs: [
-        "bpf_syscall_wrappers",
+        "bpf_headers",
         "jni_headers",
     ],
     shared_libs: [
diff --git a/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp b/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
index 2e88fc8..2146d17 100644
--- a/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
+++ b/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
@@ -25,15 +25,34 @@
 #define BPF_FD_JUST_USE_INT
 #include "BpfSyscallWrappers.h"
 
+#include "bpf/KernelVersion.h"
+
 namespace android {
 
 static jint com_android_net_module_util_BpfMap_nativeBpfFdGet(JNIEnv *env, jclass clazz,
-        jstring path, jint mode) {
+        jstring path, jint mode, jint keySize, jint valueSize) {
     ScopedUtfChars pathname(env, path);
 
     jint fd = bpf::bpfFdGet(pathname.c_str(), static_cast<unsigned>(mode));
 
-    if (fd < 0) jniThrowErrnoException(env, "nativeBpfFdGet", errno);
+    if (fd < 0) {
+        jniThrowErrnoException(env, "nativeBpfFdGet", errno);
+        return -1;
+    }
+
+    if (bpf::isAtLeastKernelVersion(4, 14, 0)) {
+        // These likely fail with -1 and set errno to EINVAL on <4.14
+        if (bpf::bpfGetFdKeySize(fd) != keySize) {
+            close(fd);
+            jniThrowErrnoException(env, "nativeBpfFdGet KeySize", EBADFD);
+            return -1;
+        }
+        if (bpf::bpfGetFdValueSize(fd) != valueSize) {
+            close(fd);
+            jniThrowErrnoException(env, "nativeBpfFdGet ValueSize", EBADFD);
+            return -1;
+        }
+    }
 
     return fd;
 }
@@ -103,7 +122,7 @@
  */
 static const JNINativeMethod gMethods[] = {
     /* name, signature, funcPtr */
-    { "nativeBpfFdGet", "(Ljava/lang/String;I)I",
+    { "nativeBpfFdGet", "(Ljava/lang/String;III)I",
         (void*) com_android_net_module_util_BpfMap_nativeBpfFdGet },
     { "nativeWriteToMapEntry", "(I[B[BI)V",
         (void*) com_android_net_module_util_BpfMap_nativeWriteToMapEntry },
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/BpfDumpTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/BpfDumpTest.java
index 4e48332..a66dacd 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/BpfDumpTest.java
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/BpfDumpTest.java
@@ -57,8 +57,8 @@
 
     @Test
     public void testToBase64EncodedString() {
-        final Struct.U32 key = new Struct.U32(TEST_KEY);
-        final Struct.U32 value = new Struct.U32(TEST_VAL);
+        final Struct.S32 key = new Struct.S32(TEST_KEY);
+        final Struct.S32 value = new Struct.S32(TEST_VAL);
 
         // Verified in python:
         //   import base64
@@ -71,15 +71,15 @@
 
     @Test
     public void testFromBase64EncodedString() {
-        Pair<Struct.U32, Struct.U32> decodedKeyValue = BpfDump.fromBase64EncodedString(
-                Struct.U32.class, Struct.U32.class, TEST_KEY_VAL_BASE64);
+        Pair<Struct.S32, Struct.S32> decodedKeyValue = BpfDump.fromBase64EncodedString(
+                Struct.S32.class, Struct.S32.class, TEST_KEY_VAL_BASE64);
         assertEquals(TEST_KEY, decodedKeyValue.first.val);
         assertEquals(TEST_VAL, decodedKeyValue.second.val);
     }
 
     private void assertThrowsIllegalArgumentException(final String testStr) {
         assertThrows(IllegalArgumentException.class,
-                () -> BpfDump.fromBase64EncodedString(Struct.U32.class, Struct.U32.class, testStr));
+                () -> BpfDump.fromBase64EncodedString(Struct.S32.class, Struct.S32.class, testStr));
     }
 
     @Test
@@ -96,7 +96,7 @@
                 TEST_KEY_VAL_BASE64 + BASE64_DELIMITER + TEST_KEY_BASE64);
     }
 
-    private String getDumpMap(final IBpfMap<Struct.U32, Struct.U32> map) {
+    private String getDumpMap(final IBpfMap<Struct.S32, Struct.S32> map) {
         final StringWriter sw = new StringWriter();
         BpfDump.dumpMap(map, new PrintWriter(sw), "mapName", "header",
                 (key, val) -> "key=" + key.val + ", val=" + val.val);
@@ -105,9 +105,9 @@
 
     @Test
     public void testDumpMap() throws Exception {
-        final IBpfMap<Struct.U32, Struct.U32> map =
-                new TestBpfMap<>(Struct.U32.class, Struct.U32.class);
-        map.updateEntry(new Struct.U32(123), new Struct.U32(456));
+        final IBpfMap<Struct.S32, Struct.S32> map =
+                new TestBpfMap<>(Struct.S32.class, Struct.S32.class);
+        map.updateEntry(new Struct.S32(123), new Struct.S32(456));
 
         final String dump = getDumpMap(map);
         assertEquals(dump, "mapName:\n"
@@ -117,10 +117,10 @@
 
     @Test
     public void testDumpMapMultipleEntries() throws Exception {
-        final IBpfMap<Struct.U32, Struct.U32> map =
-                new TestBpfMap<>(Struct.U32.class, Struct.U32.class);
-        map.updateEntry(new Struct.U32(123), new Struct.U32(456));
-        map.updateEntry(new Struct.U32(789), new Struct.U32(123));
+        final IBpfMap<Struct.S32, Struct.S32> map =
+                new TestBpfMap<>(Struct.S32.class, Struct.S32.class);
+        map.updateEntry(new Struct.S32(123), new Struct.S32(456));
+        map.updateEntry(new Struct.S32(789), new Struct.S32(123));
 
         final String dump = getDumpMap(map);
         assertTrue(dump.contains("mapName:"));
@@ -129,7 +129,7 @@
         assertTrue(dump.contains("key=789, val=123"));
     }
 
-    private String getDumpMapStatus(final IBpfMap<Struct.U32, Struct.U32> map) {
+    private String getDumpMapStatus(final IBpfMap<Struct.S32, Struct.S32> map) {
         final StringWriter sw = new StringWriter();
         BpfDump.dumpMapStatus(map, new PrintWriter(sw), "mapName", "mapPath");
         return sw.toString();
@@ -137,8 +137,8 @@
 
     @Test
     public void testGetMapStatus() {
-        final IBpfMap<Struct.U32, Struct.U32> map =
-                new TestBpfMap<>(Struct.U32.class, Struct.U32.class);
+        final IBpfMap<Struct.S32, Struct.S32> map =
+                new TestBpfMap<>(Struct.S32.class, Struct.S32.class);
         assertEquals("mapName: OK\n", getDumpMapStatus(map));
     }