make java maps grab locks
The java bpfmap fd cache has some implications:
- this won't protect against two SingleWriterBpfMap instantiations
for the same map (path) in the same process
- we don't release any locks on BpfMap destruction.
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ibb0b1f57974c307ea5e0fa699ce8d598c59f456e
diff --git a/staticlibs/device/com/android/net/module/util/BpfMap.java b/staticlibs/device/com/android/net/module/util/BpfMap.java
index da77ae8..dafff20 100644
--- a/staticlibs/device/com/android/net/module/util/BpfMap.java
+++ b/staticlibs/device/com/android/net/module/util/BpfMap.java
@@ -52,6 +52,9 @@
public static final int BPF_F_RDONLY = 1 << 3;
public static final int BPF_F_WRONLY = 1 << 4;
+ // magic value for jni consumption, invalid from kernel point of view
+ public static final int BPF_F_RDWR_EXCLUSIVE = BPF_F_RDONLY | BPF_F_WRONLY;
+
public static final int BPF_MAP_TYPE_HASH = 1;
private static final int BPF_F_NO_PREALLOC = 1;
diff --git a/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java b/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java
index 254995f..bbd921d 100644
--- a/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java
+++ b/staticlibs/device/com/android/net/module/util/SingleWriterBpfMap.java
@@ -63,7 +63,7 @@
public SingleWriterBpfMap(@NonNull final String path, final Class<K> key,
final Class<V> value) throws ErrnoException, NullPointerException {
- super(path, BPF_F_RDWR, key, value);
+ super(path, BPF_F_RDWR_EXCLUSIVE, key, value);
// Populate cache with the current map contents.
K currentKey = super.getFirstKey();
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 b92f107..1923ceb 100644
--- a/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
+++ b/staticlibs/native/bpfmapjni/com_android_net_module_util_BpfMap.cpp
@@ -35,7 +35,24 @@
jstring path, jint mode, jint keySize, jint valueSize) {
ScopedUtfChars pathname(env, path);
- jint fd = bpf::bpfFdGet(pathname.c_str(), static_cast<unsigned>(mode));
+ jint fd = -1;
+ switch (mode) {
+ case 0:
+ fd = bpf::mapRetrieveRW(pathname.c_str());
+ break;
+ case BPF_F_RDONLY:
+ fd = bpf::mapRetrieveRO(pathname.c_str());
+ break;
+ case BPF_F_WRONLY:
+ fd = bpf::mapRetrieveWO(pathname.c_str());
+ break;
+ case BPF_F_RDONLY|BPF_F_WRONLY:
+ fd = bpf::mapRetrieveExclusiveRW(pathname.c_str());
+ break;
+ default:
+ errno = EINVAL;
+ break;
+ }
if (fd < 0) {
jniThrowErrnoException(env, "nativeBpfFdGet", errno);