Update su request process

Due to changes in ec3705f2ed, the app can
no longer communicate with the dameon through a socket opened on the
daemon side due to SELinux restrictions. The workaround here is to have
the daemon decide a socket name, send it to the app, have the app create
the socket server, then finally the daemon connects to the app through
the socket.

native/jni/core/socket.cpp

@@ -6,23 +6,18 @@
 #include <socket.hpp>
 #include <utils.hpp>
 
-#define ABS_SOCKET_LEN(sun) (sizeof(sa_family_t) + strlen(sun->sun_path + 1) + 1)
+static size_t socket_len(sockaddr_un *sun) {
+	if (sun->sun_path[0])
+		return sizeof(sa_family_t) + strlen(sun->sun_path) + 1;
+	else
+		return sizeof(sa_family_t) + strlen(sun->sun_path + 1) + 1;
+}
 
-socklen_t setup_sockaddr(struct sockaddr_un *sun, const char *name) {
+socklen_t setup_sockaddr(sockaddr_un *sun, const char *name) {
 	memset(sun, 0, sizeof(*sun));
 	sun->sun_family = AF_LOCAL;
 	strcpy(sun->sun_path + 1, name);
-	return ABS_SOCKET_LEN(sun);
-}
-
-int create_rand_socket(struct sockaddr_un *sun) {
-	memset(sun, 0, sizeof(*sun));
-	sun->sun_family = AF_LOCAL;
-	gen_rand_str(sun->sun_path + 1, sizeof(sun->sun_path) - 1);
-	int fd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
-	xbind(fd, (struct sockaddr*) sun, ABS_SOCKET_LEN(sun));
-	xlisten(fd, 1);
-	return fd;
+	return socket_len(sun);
 }
 
 int socket_accept(int sockfd, int timeout) {

native/jni/include/socket.hpp

@@ -3,8 +3,8 @@
 #include <sys/un.h>
 #include <sys/socket.h>
 
-socklen_t setup_sockaddr(struct sockaddr_un *sun, const char *name);
-int create_rand_socket(struct sockaddr_un *sun);
+socklen_t setup_sockaddr(sockaddr_un *sun, const char *name);
+int create_app_socket(sockaddr_un *sun);
 int socket_accept(int sockfd, int timeout);
 void get_client_cred(int fd, struct ucred *cred);
 int recv_fd(int sockfd);

native/jni/su/connect.cpp

@@ -1,9 +1,5 @@
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <fcntl.h>
-#include <stdio.h>
 
 #include <daemon.hpp>
 #include <utils.hpp>
@@ -92,9 +88,9 @@ public:
 	}
 };
 
-static bool check_error(int fd) {
+static bool check_no_error(int fd) {
 	char buf[1024];
-	unique_ptr<FILE, decltype(&fclose)> out(xfdopen(fd, "r"), fclose);
+	auto out = xopen_file(fd, "r");
 	while (fgets(buf, sizeof(buf), out.get())) {
 		if (strncmp(buf, "Error", 5) == 0)
 			return false;
@@ -123,7 +119,7 @@ static void exec_cmd(const char *action, vector<Extra> &data,
 			.argv = args.data()
 		};
 		exec_command_sync(exec);
-		if (check_error(exec.fd))
+		if (check_no_error(exec.fd))
 			return;
 	}
 
@@ -143,7 +139,7 @@ static void exec_cmd(const char *action, vector<Extra> &data,
 		// Then try start activity without component name
 		strcpy(target, info->str[SU_MANAGER].data());
 		exec_command_sync(exec);
-		if (check_error(exec.fd))
+		if (check_no_error(exec.fd))
 			return;
 	}
 
@@ -183,12 +179,31 @@ void app_notify(const su_context &ctx) {
 	}
 }
 
-void app_socket(const char *socket, const shared_ptr<su_info> &info) {
+int app_socket(const char *name, const shared_ptr<su_info> &info) {
 	vector<Extra> extras;
 	extras.reserve(1);
-	extras.emplace_back("socket", socket);
+	extras.emplace_back("socket", name);
 
 	exec_cmd("request", extras, info, PKG_ACTIVITY);
+
+	sockaddr_un addr;
+	size_t len = setup_sockaddr(&addr, name);
+	int fd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
+	bool connected = false;
+	// Try at most 60 seconds
+	for (int i = 0; i < 600; ++i) {
+		if (connect(fd, reinterpret_cast<sockaddr *>(&addr), len) == 0) {
+			connected = true;
+			break;
+		}
+		usleep(100000);  // 100ms
+	}
+	if (connected) {
+		return fd;
+	} else {
+		close(fd);
+		return -1;
+	}
 }
 
 void socket_send_request(int fd, const shared_ptr<su_info> &info) {

native/jni/su/su.hpp

@@ -68,5 +68,5 @@ struct su_context {
 
 void app_log(const su_context &ctx);
 void app_notify(const su_context &ctx);
-void app_socket(const char *socket, const std::shared_ptr<su_info> &info);
+int app_socket(const char *name, const std::shared_ptr<su_info> &info);
 void socket_send_request(int fd, const std::shared_ptr<su_info> &info);

native/jni/su/su_daemon.cpp

@@ -139,12 +139,9 @@ static shared_ptr<su_info> get_su_info(unsigned uid) {
 	}
 
 	// If still not determined, ask manager
-	struct sockaddr_un addr;
-	int sockfd = create_rand_socket(&addr);
-
-	// Connect manager
-	app_socket(addr.sun_path + 1, info);
-	int fd = socket_accept(sockfd, 60);
+	char socket_name[32];
+	gen_rand_str(socket_name, sizeof(socket_name));
+	int fd = app_socket(socket_name, info);
 	if (fd < 0) {
 		info->access.policy = DENY;
 	} else {
@@ -153,7 +150,6 @@ static shared_ptr<su_info> get_su_info(unsigned uid) {
 		info->access.policy = ret < 0 ? DENY : static_cast<policy_t>(ret);
 		close(fd);
 	}
-	close(sockfd);
 
 	return info;
 }

native/jni/utils/files.hpp

@@ -133,3 +133,7 @@ static inline sFILE open_file(const char *path, const char *mode) {
 static inline sFILE xopen_file(const char *path, const char *mode) {
 	return sFILE(xfopen(path, mode), fclose);
 }
+
+static inline sFILE xopen_file(int fd, const char *mode) {
+	return sFILE(xfdopen(fd, mode), fclose);
+}