Services: Move to Userland/Services/

Userland/Services/SystemServer/Service.cpp

@@ -0,0 +1,376 @@
+/*
+ * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "Service.h"
+#include <AK/HashMap.h>
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
+#include <LibCore/ConfigFile.h>
+#include <LibCore/File.h>
+#include <LibCore/Socket.h>
+#include <grp.h>
+#include <libgen.h>
+#include <pwd.h>
+#include <sched.h>
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+static HashMap<pid_t, Service*> s_service_map;
+
+Service* Service::find_by_pid(pid_t pid)
+{
+    auto it = s_service_map.find(pid);
+    if (it == s_service_map.end())
+        return nullptr;
+    return (*it).value;
+}
+
+void Service::setup_socket()
+{
+    ASSERT(!m_socket_path.is_null());
+    ASSERT(m_socket_fd == -1);
+
+    auto ok = Core::File::ensure_parent_directories(m_socket_path);
+    ASSERT(ok);
+
+    // Note: we use SOCK_CLOEXEC here to make sure we don't leak every socket to
+    // all the clients. We'll make the one we do need to pass down !CLOEXEC later
+    // after forking off the process.
+    m_socket_fd = socket(AF_LOCAL, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
+    if (m_socket_fd < 0) {
+        perror("socket");
+        ASSERT_NOT_REACHED();
+    }
+
+    if (m_account.has_value()) {
+        auto& account = m_account.value();
+        if (fchown(m_socket_fd, account.uid(), account.gid()) < 0) {
+            perror("fchown");
+            ASSERT_NOT_REACHED();
+        }
+    }
+
+    if (fchmod(m_socket_fd, m_socket_permissions) < 0) {
+        perror("fchmod");
+        ASSERT_NOT_REACHED();
+    }
+
+    auto socket_address = Core::SocketAddress::local(m_socket_path);
+    auto un_optional = socket_address.to_sockaddr_un();
+    if (!un_optional.has_value()) {
+        dbg() << "Socket name " << m_socket_path << " is too long. BUG! This should have failed earlier!";
+        ASSERT_NOT_REACHED();
+    }
+    auto un = un_optional.value();
+    int rc = bind(m_socket_fd, (const sockaddr*)&un, sizeof(un));
+    if (rc < 0) {
+        perror("bind");
+        ASSERT_NOT_REACHED();
+    }
+
+    rc = listen(m_socket_fd, 16);
+    if (rc < 0) {
+        perror("listen");
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void Service::setup_notifier()
+{
+    ASSERT(m_lazy);
+    ASSERT(m_socket_fd >= 0);
+    ASSERT(!m_socket_notifier);
+
+    m_socket_notifier = Core::Notifier::construct(m_socket_fd, Core::Notifier::Event::Read, this);
+    m_socket_notifier->on_ready_to_read = [this] {
+        handle_socket_connection();
+    };
+}
+
+void Service::handle_socket_connection()
+{
+#ifdef SERVICE_DEBUG
+    dbg() << "Ready to read on behalf of " << name();
+#endif
+    if (m_accept_socket_connections) {
+        int accepted_fd = accept(m_socket_fd, nullptr, nullptr);
+        if (accepted_fd < 0) {
+            perror("accept");
+            return;
+        }
+        spawn(accepted_fd);
+        close(accepted_fd);
+    } else {
+        remove_child(*m_socket_notifier);
+        m_socket_notifier = nullptr;
+        spawn(m_socket_fd);
+    }
+}
+
+void Service::activate()
+{
+    ASSERT(m_pid < 0);
+
+    if (m_lazy)
+        setup_notifier();
+    else
+        spawn(m_socket_fd);
+}
+
+void Service::spawn(int socket_fd)
+{
+#ifdef SERVICE_DEBUG
+    dbg() << "Spawning " << name();
+#endif
+
+    m_run_timer.start();
+    pid_t pid = fork();
+
+    if (pid < 0) {
+        perror("fork");
+        dbg() << "Failed to spawn " << name() << ". Sucks, dude :(";
+    } else if (pid == 0) {
+        // We are the child.
+
+        if (!m_working_directory.is_null()) {
+            if (chdir(m_working_directory.characters()) < 0) {
+                perror("chdir");
+                ASSERT_NOT_REACHED();
+            }
+        }
+
+        struct sched_param p;
+        p.sched_priority = m_priority;
+        int rc = sched_setparam(0, &p);
+        if (rc < 0) {
+            perror("sched_setparam");
+            ASSERT_NOT_REACHED();
+        }
+
+        if (!m_stdio_file_path.is_null()) {
+            close(STDIN_FILENO);
+            int fd = open_with_path_length(m_stdio_file_path.characters(), m_stdio_file_path.length(), O_RDWR, 0);
+            ASSERT(fd <= 0);
+            if (fd < 0) {
+                perror("open");
+                ASSERT_NOT_REACHED();
+            }
+            dup2(STDIN_FILENO, STDOUT_FILENO);
+            dup2(STDIN_FILENO, STDERR_FILENO);
+
+            if (isatty(STDIN_FILENO)) {
+                ioctl(STDIN_FILENO, TIOCSCTTY);
+            }
+        } else {
+            if (isatty(STDIN_FILENO)) {
+                ioctl(STDIN_FILENO, TIOCNOTTY);
+            }
+            close(STDIN_FILENO);
+            close(STDOUT_FILENO);
+            close(STDERR_FILENO);
+
+            int fd = open("/dev/null", O_RDWR);
+            ASSERT(fd == STDIN_FILENO);
+            dup2(STDIN_FILENO, STDOUT_FILENO);
+            dup2(STDIN_FILENO, STDERR_FILENO);
+        }
+
+        if (socket_fd >= 0) {
+            ASSERT(!m_socket_path.is_null());
+            ASSERT(socket_fd > 3);
+            dup2(socket_fd, 3);
+            // The new descriptor is !CLOEXEC here.
+            setenv("SOCKET_TAKEOVER", "1", true);
+        }
+
+        if (m_account.has_value()) {
+            auto& account = m_account.value();
+            if (setgid(account.gid()) < 0 || setgroups(account.extra_gids().size(), account.extra_gids().data()) < 0 || setuid(account.uid()) < 0) {
+                dbgln("Failed to drop privileges (GID={}, UID={})\n", account.gid(), account.uid());
+                exit(1);
+            }
+            setenv("HOME", account.home_directory().characters(), true);
+        }
+
+        for (String& env : m_environment)
+            putenv(const_cast<char*>(env.characters()));
+
+        char* argv[m_extra_arguments.size() + 2];
+        argv[0] = const_cast<char*>(m_executable_path.characters());
+        for (size_t i = 0; i < m_extra_arguments.size(); i++)
+            argv[i + 1] = const_cast<char*>(m_extra_arguments[i].characters());
+        argv[m_extra_arguments.size() + 1] = nullptr;
+
+        rc = execv(argv[0], argv);
+        perror("exec");
+        ASSERT_NOT_REACHED();
+    } else if (!m_multi_instance) {
+        // We are the parent.
+        m_pid = pid;
+        s_service_map.set(pid, this);
+    }
+}
+
+void Service::did_exit(int exit_code)
+{
+    ASSERT(m_pid > 0);
+    ASSERT(!m_multi_instance);
+
+    dbg() << "Service " << name() << " has exited with exit code " << exit_code;
+
+    s_service_map.remove(m_pid);
+    m_pid = -1;
+
+    if (!m_keep_alive)
+        return;
+
+    int run_time_in_msec = m_run_timer.elapsed();
+    bool exited_successfully = exit_code == 0;
+
+    if (!exited_successfully && run_time_in_msec < 1000) {
+        switch (m_restart_attempts) {
+        case 0:
+            dbgln("Trying again");
+            break;
+        case 1:
+            dbgln("Third time's a charm?");
+            break;
+        default:
+            dbg() << "Giving up on " << name() << ". Good luck!";
+            return;
+        }
+        m_restart_attempts++;
+    }
+
+    activate();
+}
+
+Service::Service(const Core::ConfigFile& config, const StringView& name)
+    : Core::Object(nullptr)
+{
+    ASSERT(config.has_group(name));
+
+    set_name(name);
+    m_executable_path = config.read_entry(name, "Executable", String::format("/bin/%s", this->name().characters()));
+    m_extra_arguments = config.read_entry(name, "Arguments", "").split(' ');
+    m_stdio_file_path = config.read_entry(name, "StdIO");
+
+    String prio = config.read_entry(name, "Priority");
+    if (prio == "low")
+        m_priority = 10;
+    else if (prio == "normal" || prio.is_null())
+        m_priority = 30;
+    else if (prio == "high")
+        m_priority = 50;
+    else
+        ASSERT_NOT_REACHED();
+
+    m_keep_alive = config.read_bool_entry(name, "KeepAlive");
+    m_lazy = config.read_bool_entry(name, "Lazy");
+
+    m_user = config.read_entry(name, "User");
+    if (!m_user.is_null()) {
+        auto result = Core::Account::from_name(m_user.characters());
+        if (result.is_error())
+            warnln("Failed to resolve user {}: {}", m_user, result.error());
+        else
+            m_account = result.value();
+    }
+
+    m_working_directory = config.read_entry(name, "WorkingDirectory");
+    m_environment = config.read_entry(name, "Environment").split(' ');
+    m_boot_modes = config.read_entry(name, "BootModes", "graphical").split(',');
+    m_multi_instance = config.read_bool_entry(name, "MultiInstance");
+    m_accept_socket_connections = config.read_bool_entry(name, "AcceptSocketConnections");
+
+    m_socket_path = config.read_entry(name, "Socket");
+
+    // Lazy requires Socket.
+    ASSERT(!m_lazy || !m_socket_path.is_null());
+    // AcceptSocketConnections always requires Socket, Lazy, and MultiInstance.
+    ASSERT(!m_accept_socket_connections || (!m_socket_path.is_null() && m_lazy && m_multi_instance));
+    // MultiInstance doesn't work with KeepAlive.
+    ASSERT(!m_multi_instance || !m_keep_alive);
+    // Socket path (plus NUL) must fit into the structs sent to the Kernel.
+    ASSERT(m_socket_path.length() < UNIX_PATH_MAX);
+
+    if (!m_socket_path.is_null() && is_enabled()) {
+        auto socket_permissions_string = config.read_entry(name, "SocketPermissions", "0600");
+        m_socket_permissions = strtol(socket_permissions_string.characters(), nullptr, 8) & 04777;
+        setup_socket();
+    }
+}
+
+void Service::save_to(JsonObject& json)
+{
+    Core::Object::save_to(json);
+
+    json.set("executable_path", m_executable_path);
+
+    // FIXME: This crashes Inspector.
+    /*
+    JsonArray extra_args;
+    for (String& arg : m_extra_arguments)
+        extra_args.append(arg);
+    json.set("extra_arguments", move(extra_args));
+
+    JsonArray boot_modes;
+    for (String& mode : m_boot_modes)
+        boot_modes.append(mode);
+    json.set("boot_modes", boot_modes);
+
+    JsonArray environment;
+    for (String& env : m_environment)
+        boot_modes.append(env);
+    json.set("environment", environment);
+    */
+
+    json.set("stdio_file_path", m_stdio_file_path);
+    json.set("priority", m_priority);
+    json.set("keep_alive", m_keep_alive);
+    json.set("socket_path", m_socket_path);
+    json.set("socket_permissions", m_socket_permissions);
+    json.set("lazy", m_lazy);
+    json.set("user", m_user);
+    json.set("multi_instance", m_multi_instance);
+    json.set("accept_socket_connections", m_accept_socket_connections);
+
+    if (m_pid > 0)
+        json.set("pid", m_pid);
+    else
+        json.set("pid", nullptr);
+
+    json.set("restart_attempts", m_restart_attempts);
+    json.set("working_directory", m_working_directory);
+}
+
+bool Service::is_enabled() const
+{
+    extern String g_boot_mode;
+    return m_boot_modes.contains_slow(g_boot_mode);
+}