[CLATJ#18] libclat: move clat tc and bpf utilis from netd

Move native functions from ClatdController and TcUtils to libclat
for jni ClatdCoordinator.

Bug: 212345928
Test: atest libclat_test
Change-Id: Ia4b344b07537d57c3e4ff1285b0e7b17e0c63c3e
diff --git a/service/native/libs/libclat/bpfhelper.cpp b/service/native/libs/libclat/bpfhelper.cpp
new file mode 100644
index 0000000..6e230d0
--- /dev/null
+++ b/service/native/libs/libclat/bpfhelper.cpp
@@ -0,0 +1,231 @@
+/*
+ * Copyright 2021 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.
+ *
+ * main.c - main function
+ */
+#define LOG_TAG "bpfhelper"
+
+#include "libclat/bpfhelper.h"
+
+#include <android-base/unique_fd.h>
+#include <log/log.h>
+
+#include "bpf/BpfMap.h"
+#include "libclat/TcUtils.h"
+
+#define DEVICEPREFIX "v4-"
+
+using android::base::unique_fd;
+using android::net::RAWIP;
+using android::net::getClatEgress4MapFd;
+using android::net::getClatIngress6MapFd;
+using android::net::getClatEgress4ProgFd;
+using android::net::getClatIngress6ProgFd;
+using android::net::tcQdiscAddDevClsact;
+using android::net::tcFilterAddDevEgressClatIpv4;
+using android::net::tcFilterAddDevIngressClatIpv6;
+using android::net::tcFilterDelDevEgressClatIpv4;
+using android::net::tcFilterDelDevIngressClatIpv6;
+using android::bpf::BpfMap;
+
+BpfMap<ClatEgress4Key, ClatEgress4Value> mClatEgress4Map;
+BpfMap<ClatIngress6Key, ClatIngress6Value> mClatIngress6Map;
+
+namespace android {
+namespace net {
+namespace clat {
+
+// TODO: have a clearMap function to remove all stubs while system server crash.
+// For long term, move bpf access into java and map initialization should live
+// ClatCoordinator constructor.
+int initMaps(void) {
+    int rv = getClatEgress4MapFd();
+    if (rv < 0) {
+        ALOGE("getClatEgress4MapFd() failure: %s", strerror(-rv));
+        return -rv;
+    }
+    mClatEgress4Map.reset(rv);
+
+    rv = getClatIngress6MapFd();
+    if (rv < 0) {
+        ALOGE("getClatIngress6MapFd() failure: %s", strerror(-rv));
+        mClatEgress4Map.reset(-1);
+        return -rv;
+    }
+    mClatIngress6Map.reset(rv);
+
+    return 0;
+}
+
+void maybeStartBpf(const ClatdTracker& tracker) {
+    auto isEthernet = android::net::isEthernet(tracker.iface);
+    if (!isEthernet.ok()) {
+        ALOGE("isEthernet(%s[%d]) failure: %s", tracker.iface, tracker.ifIndex,
+              isEthernet.error().message().c_str());
+        return;
+    }
+
+    // This program will be attached to the v4-* interface which is a TUN and thus always rawip.
+    int rv = getClatEgress4ProgFd(RAWIP);
+    if (rv < 0) {
+        ALOGE("getClatEgress4ProgFd(RAWIP) failure: %s", strerror(-rv));
+        return;
+    }
+    unique_fd txRawIpProgFd(rv);
+
+    rv = getClatIngress6ProgFd(isEthernet.value());
+    if (rv < 0) {
+        ALOGE("getClatIngress6ProgFd(%d) failure: %s", isEthernet.value(), strerror(-rv));
+        return;
+    }
+    unique_fd rxProgFd(rv);
+
+    ClatEgress4Key txKey = {
+            .iif = tracker.v4ifIndex,
+            .local4 = tracker.v4,
+    };
+    ClatEgress4Value txValue = {
+            .oif = tracker.ifIndex,
+            .local6 = tracker.v6,
+            .pfx96 = tracker.pfx96,
+            .oifIsEthernet = isEthernet.value(),
+    };
+
+    auto ret = mClatEgress4Map.writeValue(txKey, txValue, BPF_ANY);
+    if (!ret.ok()) {
+        ALOGE("mClatEgress4Map.writeValue failure: %s", strerror(ret.error().code()));
+        return;
+    }
+
+    ClatIngress6Key rxKey = {
+            .iif = tracker.ifIndex,
+            .pfx96 = tracker.pfx96,
+            .local6 = tracker.v6,
+    };
+    ClatIngress6Value rxValue = {
+            // TODO: move all the clat code to eBPF and remove the tun interface entirely.
+            .oif = tracker.v4ifIndex,
+            .local4 = tracker.v4,
+    };
+
+    ret = mClatIngress6Map.writeValue(rxKey, rxValue, BPF_ANY);
+    if (!ret.ok()) {
+        ALOGE("mClatIngress6Map.writeValue failure: %s", strerror(ret.error().code()));
+        ret = mClatEgress4Map.deleteValue(txKey);
+        if (!ret.ok())
+            ALOGE("mClatEgress4Map.deleteValue failure: %s", strerror(ret.error().code()));
+        return;
+    }
+
+    // We do tc setup *after* populating the maps, so scanning through them
+    // can always be used to tell us what needs cleanup.
+
+    // Usually the clsact will be added in RouteController::addInterfaceToPhysicalNetwork.
+    // But clat is started before the v4- interface is added to the network. The clat startup have
+    // to add clsact of v4- tun interface first for adding bpf filter in maybeStartBpf.
+    // TODO: move "qdisc add clsact" of v4- tun interface out from ClatdController.
+    rv = tcQdiscAddDevClsact(tracker.v4ifIndex);
+    if (rv) {
+        ALOGE("tcQdiscAddDevClsact(%d[%s]) failure: %s", tracker.v4ifIndex, tracker.v4iface,
+              strerror(-rv));
+        ret = mClatEgress4Map.deleteValue(txKey);
+        if (!ret.ok())
+            ALOGE("mClatEgress4Map.deleteValue failure: %s", strerror(ret.error().code()));
+        ret = mClatIngress6Map.deleteValue(rxKey);
+        if (!ret.ok())
+            ALOGE("mClatIngress6Map.deleteValue failure: %s", strerror(ret.error().code()));
+        return;
+    }
+
+    rv = tcFilterAddDevEgressClatIpv4(tracker.v4ifIndex, txRawIpProgFd, RAWIP);
+    if (rv) {
+        ALOGE("tcFilterAddDevEgressClatIpv4(%d[%s], RAWIP) failure: %s", tracker.v4ifIndex,
+              tracker.v4iface, strerror(-rv));
+
+        // The v4- interface clsact is not deleted for unwinding error because once it is created
+        // with interface addition, the lifetime is till interface deletion. Moreover, the clsact
+        // has no clat filter now. It should not break anything.
+
+        ret = mClatEgress4Map.deleteValue(txKey);
+        if (!ret.ok())
+            ALOGE("mClatEgress4Map.deleteValue failure: %s", strerror(ret.error().code()));
+        ret = mClatIngress6Map.deleteValue(rxKey);
+        if (!ret.ok())
+            ALOGE("mClatIngress6Map.deleteValue failure: %s", strerror(ret.error().code()));
+        return;
+    }
+
+    rv = tcFilterAddDevIngressClatIpv6(tracker.ifIndex, rxProgFd, isEthernet.value());
+    if (rv) {
+        ALOGE("tcFilterAddDevIngressClatIpv6(%d[%s], %d) failure: %s", tracker.ifIndex,
+              tracker.iface, isEthernet.value(), strerror(-rv));
+        rv = tcFilterDelDevEgressClatIpv4(tracker.v4ifIndex);
+        if (rv) {
+            ALOGE("tcFilterDelDevEgressClatIpv4(%d[%s]) failure: %s", tracker.v4ifIndex,
+                  tracker.v4iface, strerror(-rv));
+        }
+
+        // The v4- interface clsact is not deleted. See the reason in the error unwinding code of
+        // the egress filter attaching of v4- tun interface.
+
+        ret = mClatEgress4Map.deleteValue(txKey);
+        if (!ret.ok())
+            ALOGE("mClatEgress4Map.deleteValue failure: %s", strerror(ret.error().code()));
+        ret = mClatIngress6Map.deleteValue(rxKey);
+        if (!ret.ok())
+            ALOGE("mClatIngress6Map.deleteValue failure: %s", strerror(ret.error().code()));
+        return;
+    }
+
+    // success
+}
+
+void maybeStopBpf(const ClatdTracker& tracker) {
+    int rv = tcFilterDelDevIngressClatIpv6(tracker.ifIndex);
+    if (rv < 0) {
+        ALOGE("tcFilterDelDevIngressClatIpv6(%d[%s]) failure: %s", tracker.ifIndex, tracker.iface,
+              strerror(-rv));
+    }
+
+    rv = tcFilterDelDevEgressClatIpv4(tracker.v4ifIndex);
+    if (rv < 0) {
+        ALOGE("tcFilterDelDevEgressClatIpv4(%d[%s]) failure: %s", tracker.v4ifIndex,
+              tracker.v4iface, strerror(-rv));
+    }
+
+    // We cleanup the maps last, so scanning through them can be used to
+    // determine what still needs cleanup.
+
+    ClatEgress4Key txKey = {
+            .iif = tracker.v4ifIndex,
+            .local4 = tracker.v4,
+    };
+
+    auto ret = mClatEgress4Map.deleteValue(txKey);
+    if (!ret.ok()) ALOGE("mClatEgress4Map.deleteValue failure: %s", strerror(ret.error().code()));
+
+    ClatIngress6Key rxKey = {
+            .iif = tracker.ifIndex,
+            .pfx96 = tracker.pfx96,
+            .local6 = tracker.v6,
+    };
+
+    ret = mClatIngress6Map.deleteValue(rxKey);
+    if (!ret.ok()) ALOGE("mClatIngress6Map.deleteValue failure: %s", strerror(ret.error().code()));
+}
+
+}  // namespace clat
+}  // namespace net
+}  // namespace android