libbinder: vsock support for RPC

This adds support for binder RPC to be used with virtual sockets.

One decision made here - should RpcConnection.h take a sockaddr object,
or not? I've chosen not to expose sockaddr directly because it is a
low-level type (specifically for unix domain sockets, where the path may
not be null-terminated).

Fixes: 182938272
Test: binderRpcTest
Change-Id: I29bbbd2745f71d8ed7d4b8f8273fce28de0a9779
diff --git a/libs/binder/RpcConnection.cpp b/libs/binder/RpcConnection.cpp
index 83a1618..dab3246 100644
--- a/libs/binder/RpcConnection.cpp
+++ b/libs/binder/RpcConnection.cpp
@@ -20,6 +20,7 @@
 
 #include <binder/Parcel.h>
 #include <binder/Stability.h>
+#include <utils/String8.h>
 
 #include "RpcState.h"
 #include "RpcWireFormat.h"
@@ -29,14 +30,20 @@
 #include <sys/un.h>
 #include <unistd.h>
 
-#if defined(__GLIBC__)
+#ifdef __GLIBC__
 extern "C" pid_t gettid();
 #endif
 
+#ifdef __BIONIC__
+#include <linux/vm_sockets.h>
+#endif
+
 namespace android {
 
 using base::unique_fd;
 
+RpcConnection::SocketAddress::~SocketAddress() {}
+
 RpcConnection::RpcConnection() {
     LOG_RPC_DETAIL("RpcConnection created %p", this);
 
@@ -50,65 +57,68 @@
     return new RpcConnection;
 }
 
+class UnixSocketAddress : public RpcConnection::SocketAddress {
+public:
+    explicit UnixSocketAddress(const char* path) : mAddr({.sun_family = AF_UNIX}) {
+        unsigned int pathLen = strlen(path) + 1;
+        LOG_ALWAYS_FATAL_IF(pathLen > sizeof(mAddr.sun_path), "%u %s", pathLen, path);
+        memcpy(mAddr.sun_path, path, pathLen);
+    }
+    virtual ~UnixSocketAddress() {}
+    std::string toString() const override {
+        return String8::format("path '%.*s'", static_cast<int>(sizeof(mAddr.sun_path)),
+                               mAddr.sun_path)
+                .c_str();
+    }
+    const sockaddr* addr() const override { return reinterpret_cast<const sockaddr*>(&mAddr); }
+    size_t addrSize() const override { return sizeof(mAddr); }
+
+private:
+    sockaddr_un mAddr;
+};
+
 bool RpcConnection::setupUnixDomainServer(const char* path) {
-    LOG_ALWAYS_FATAL_IF(mServer.get() != -1, "Only supports one server now");
-
-    unique_fd serverFd(TEMP_FAILURE_RETRY(socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0)));
-    if (serverFd == -1) {
-        ALOGE("Could not create socket at %s: %s", path, strerror(errno));
-        return false;
-    }
-
-    struct sockaddr_un addr = {
-            .sun_family = AF_UNIX,
-    };
-
-    unsigned int pathLen = strlen(path) + 1;
-    LOG_ALWAYS_FATAL_IF(pathLen > sizeof(addr.sun_path), "%u", pathLen);
-    memcpy(addr.sun_path, path, pathLen);
-
-    if (0 != TEMP_FAILURE_RETRY(bind(serverFd.get(), (struct sockaddr*)&addr, sizeof(addr)))) {
-        ALOGE("Could not bind socket at %s: %s", path, strerror(errno));
-        return false;
-    }
-
-    if (0 != TEMP_FAILURE_RETRY(listen(serverFd.get(), 1 /*backlog*/))) {
-        ALOGE("Could not listen socket at %s: %s", path, strerror(errno));
-        return false;
-    }
-
-    mServer = std::move(serverFd);
-    return true;
+    return addServer(UnixSocketAddress(path));
 }
 
 bool RpcConnection::addUnixDomainClient(const char* path) {
-    LOG_RPC_DETAIL("Connecting on path: %s", path);
-
-    unique_fd serverFd(TEMP_FAILURE_RETRY(socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0)));
-    if (serverFd == -1) {
-        ALOGE("Could not create socket at %s: %s", path, strerror(errno));
-        return false;
-    }
-
-    struct sockaddr_un addr = {
-            .sun_family = AF_UNIX,
-    };
-
-    unsigned int pathLen = strlen(path) + 1;
-    LOG_ALWAYS_FATAL_IF(pathLen > sizeof(addr.sun_path), "%u", pathLen);
-    memcpy(addr.sun_path, path, pathLen);
-
-    if (0 != TEMP_FAILURE_RETRY(connect(serverFd.get(), (struct sockaddr*)&addr, sizeof(addr)))) {
-        ALOGE("Could not connect socket at %s: %s", path, strerror(errno));
-        return false;
-    }
-
-    LOG_RPC_DETAIL("Unix domain client with fd %d", serverFd.get());
-
-    addClient(std::move(serverFd));
-    return true;
+    return addClient(UnixSocketAddress(path));
 }
 
+#ifdef __BIONIC__
+
+class VsockSocketAddress : public RpcConnection::SocketAddress {
+public:
+    VsockSocketAddress(unsigned int cid, unsigned int port)
+          : mAddr({
+                    .svm_family = AF_VSOCK,
+                    .svm_port = port,
+                    .svm_cid = cid,
+            }) {}
+    virtual ~VsockSocketAddress() {}
+    std::string toString() const override {
+        return String8::format("cid %du port %du", mAddr.svm_cid, mAddr.svm_port).c_str();
+    }
+    const sockaddr* addr() const override { return reinterpret_cast<const sockaddr*>(&mAddr); }
+    size_t addrSize() const override { return sizeof(mAddr); }
+
+private:
+    sockaddr_vm mAddr;
+};
+
+bool RpcConnection::setupVsockServer(unsigned int port) {
+    // realizing value w/ this type at compile time to avoid ubsan abort
+    constexpr unsigned int kAnyCid = VMADDR_CID_ANY;
+
+    return addServer(VsockSocketAddress(kAnyCid, port));
+}
+
+bool RpcConnection::addVsockClient(unsigned int cid, unsigned int port) {
+    return addClient(VsockSocketAddress(cid, port));
+}
+
+#endif // __BIONIC__
+
 sp<IBinder> RpcConnection::getRootObject() {
     ExclusiveSocket socket(this, SocketUse::CLIENT);
     return state()->getRootObject(socket.fd(), this);
@@ -130,11 +140,8 @@
 void RpcConnection::join() {
     // establish a connection
     {
-        struct sockaddr_un clientSa;
-        socklen_t clientSaLen = sizeof(clientSa);
-
-        unique_fd clientFd(TEMP_FAILURE_RETRY(
-                accept4(mServer.get(), (struct sockaddr*)&clientSa, &clientSaLen, SOCK_CLOEXEC)));
+        unique_fd clientFd(
+                TEMP_FAILURE_RETRY(accept4(mServer.get(), nullptr, 0 /*length*/, SOCK_CLOEXEC)));
         if (clientFd < 0) {
             // If this log becomes confusing, should save more state from setupUnixDomainServer
             // in order to output here.
@@ -144,7 +151,7 @@
 
         LOG_RPC_DETAIL("accept4 on fd %d yields fd %d", mServer.get(), clientFd.get());
 
-        addServer(std::move(clientFd));
+        assignServerToThisThread(std::move(clientFd));
     }
 
     // We may not use the connection we just established (two threads might
@@ -170,14 +177,57 @@
     return mForServer;
 }
 
-void RpcConnection::addClient(base::unique_fd&& fd) {
-    std::lock_guard<std::mutex> _l(mSocketMutex);
-    sp<ConnectionSocket> connection = new ConnectionSocket();
-    connection->fd = std::move(fd);
-    mClients.push_back(connection);
+bool RpcConnection::addServer(const SocketAddress& addr) {
+    LOG_ALWAYS_FATAL_IF(mServer.get() != -1, "Each RpcConnection can only have one server.");
+
+    unique_fd serverFd(
+            TEMP_FAILURE_RETRY(socket(addr.addr()->sa_family, SOCK_STREAM | SOCK_CLOEXEC, 0)));
+    if (serverFd == -1) {
+        ALOGE("Could not create socket: %s", strerror(errno));
+        return false;
+    }
+
+    if (0 != TEMP_FAILURE_RETRY(bind(serverFd.get(), addr.addr(), addr.addrSize()))) {
+        int savedErrno = errno;
+        ALOGE("Could not bind socket at %s: %s", addr.toString().c_str(), strerror(savedErrno));
+        return false;
+    }
+
+    if (0 != TEMP_FAILURE_RETRY(listen(serverFd.get(), 1 /*backlog*/))) {
+        int savedErrno = errno;
+        ALOGE("Could not listen socket at %s: %s", addr.toString().c_str(), strerror(savedErrno));
+        return false;
+    }
+
+    mServer = std::move(serverFd);
+    return true;
 }
 
-void RpcConnection::addServer(base::unique_fd&& fd) {
+bool RpcConnection::addClient(const SocketAddress& addr) {
+    unique_fd serverFd(
+            TEMP_FAILURE_RETRY(socket(addr.addr()->sa_family, SOCK_STREAM | SOCK_CLOEXEC, 0)));
+    if (serverFd == -1) {
+        int savedErrno = errno;
+        ALOGE("Could not create socket at %s: %s", addr.toString().c_str(), strerror(savedErrno));
+        return false;
+    }
+
+    if (0 != TEMP_FAILURE_RETRY(connect(serverFd.get(), addr.addr(), addr.addrSize()))) {
+        int savedErrno = errno;
+        ALOGE("Could not connect socket at %s: %s", addr.toString().c_str(), strerror(savedErrno));
+        return false;
+    }
+
+    LOG_RPC_DETAIL("Socket at %s client with fd %d", addr.toString().c_str(), serverFd.get());
+
+    std::lock_guard<std::mutex> _l(mSocketMutex);
+    sp<ConnectionSocket> connection = new ConnectionSocket();
+    connection->fd = std::move(serverFd);
+    mClients.push_back(connection);
+    return true;
+}
+
+void RpcConnection::assignServerToThisThread(base::unique_fd&& fd) {
     std::lock_guard<std::mutex> _l(mSocketMutex);
     sp<ConnectionSocket> connection = new ConnectionSocket();
     connection->fd = std::move(fd);