+
+int import_fork_tar(const char *path, pid_t *ret) {
+ _cleanup_close_pair_ int pipefd[2] = { -1, -1 };
+ pid_t pid;
+ int r;
+
+ assert(path);
+ assert(ret);
+
+ if (pipe2(pipefd, O_CLOEXEC) < 0)
+ return log_error_errno(errno, "Failed to create pipe for tar: %m");
+
+ pid = fork();
+ if (pid < 0)
+ return log_error_errno(errno, "Failed to fork off tar: %m");
+
+ if (pid == 0) {
+ int null_fd;
+ uint64_t retain =
+ (1ULL << CAP_CHOWN) |
+ (1ULL << CAP_FOWNER) |
+ (1ULL << CAP_FSETID) |
+ (1ULL << CAP_MKNOD) |
+ (1ULL << CAP_SETFCAP) |
+ (1ULL << CAP_DAC_OVERRIDE);
+
+ /* Child */
+
+ reset_all_signal_handlers();
+ reset_signal_mask();
+ assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
+
+ pipefd[1] = safe_close(pipefd[1]);
+
+ if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
+ log_error_errno(errno, "Failed to dup2() fd: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ if (pipefd[0] != STDIN_FILENO)
+ pipefd[0] = safe_close(pipefd[0]);
+
+ null_fd = open("/dev/null", O_WRONLY|O_NOCTTY);
+ if (null_fd < 0) {
+ log_error_errno(errno, "Failed to open /dev/null: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) {
+ log_error_errno(errno, "Failed to dup2() fd: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ if (null_fd != STDOUT_FILENO)
+ null_fd = safe_close(null_fd);
+
+ fd_cloexec(STDIN_FILENO, false);
+ fd_cloexec(STDOUT_FILENO, false);
+ fd_cloexec(STDERR_FILENO, false);
+
+ if (unshare(CLONE_NEWNET) < 0)
+ log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");
+
+ r = capability_bounding_set_drop(~retain, true);
+ if (r < 0)
+ log_error_errno(r, "Failed to drop capabilities, ignoring: %m");
+
+ execlp("tar", "tar", "--numeric-owner", "-C", path, "-px", NULL);
+ log_error_errno(errno, "Failed to execute tar: %m");
+ _exit(EXIT_FAILURE);
+ }
+
+ pipefd[0] = safe_close(pipefd[0]);
+ r = pipefd[1];
+ pipefd[1] = -1;
+
+ *ret = pid;
+
+ return r;
+}