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SystemServer+LibCore: Allow service to request multiple sockets

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SystemServer only allowed a single socket to be created for a service
before this.  Now, SystemServer will allow any amount of sockets.  The
sockets can be defined like so:

[SomeService]
Socket=/tmp/portal/socket1,/tmp/portal/socket2,/tmp/portal/socket3
SocketPermissions=660,600

The last item in SocketPermissions is applied to the remainder of the
sockets in the Socket= line, so multiple sockets can have the same
permissions without having to repeat them.

Defining multiple sockets is not allowed for socket-activated services
at the moment, and wouldn't make much sense anyway.

This patch also makes socket takeovers more robust by removing the
assumption that the socket will always be passed in fd 3.  Now, the
SOCKET_TAKEOVER environment variable carries information about which
endpoint corresponds to which socket, like so:

SOCKET_TAKEOVER=/tmp/portal/socket1:3 /tmp/portal/socket2:4

and LocalServer/LocalService will parse this automatically and select
the correct one.  The old behavior of getting the default socket is
preserved so long as the service only requests a single socket in
SystemServer.ini.
This commit is contained in:
sin-ack 2021-04-14 21:35:49 +00:00 • committed by Andreas Kling
parent 4316e817db
commit 5b95850e28
6 changed files with 178 additions and 65 deletions
Download patch file Download diff file Expand all files Collapse all files

123
Userland/Services/SystemServer/Service.cpp
View file

@ -29,6 +29,7 @@
#include <AK/HashMap.h>
#include <AK/JsonArray.h>
#include <AK/JsonObject.h>
#include <AK/StringBuilder.h>
#include <LibCore/ConfigFile.h>
#include <LibCore/File.h>
#include <LibCore/Socket.h>
@ -51,63 +52,69 @@ Service* Service::find_by_pid(pid_t pid)
return (*it).value;
}
void Service::setup_socket()
void Service::setup_socket(SocketDescriptor& socket)
{
VERIFY(!m_socket_path.is_null());
VERIFY(m_socket_fd == -1);
VERIFY(socket.fd == -1);
auto ok = Core::File::ensure_parent_directories(m_socket_path);
auto ok = Core::File::ensure_parent_directories(socket.path);
VERIFY(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) {
int socket_fd = ::socket(AF_LOCAL, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
if (socket_fd < 0) {
perror("socket");
VERIFY_NOT_REACHED();
}
socket.fd = socket_fd;
if (m_account.has_value()) {
auto& account = m_account.value();
if (fchown(m_socket_fd, account.uid(), account.gid()) < 0) {
if (fchown(socket_fd, account.uid(), account.gid()) < 0) {
perror("fchown");
VERIFY_NOT_REACHED();
}
}
if (fchmod(m_socket_fd, m_socket_permissions) < 0) {
if (fchmod(socket_fd, socket.permissions) < 0) {
perror("fchmod");
VERIFY_NOT_REACHED();
}
auto socket_address = Core::SocketAddress::local(m_socket_path);
auto socket_address = Core::SocketAddress::local(socket.path);
auto un_optional = socket_address.to_sockaddr_un();
if (!un_optional.has_value()) {
dbgln("Socket name {} is too long. BUG! This should have failed earlier!", m_socket_path);
dbgln("Socket name {} is too long. BUG! This should have failed earlier!", socket.path);
VERIFY_NOT_REACHED();
}
auto un = un_optional.value();
int rc = bind(m_socket_fd, (const sockaddr*)&un, sizeof(un));
int rc = bind(socket_fd, (const sockaddr*)&un, sizeof(un));
if (rc < 0) {
perror("bind");
VERIFY_NOT_REACHED();
}
rc = listen(m_socket_fd, 16);
rc = listen(socket_fd, 16);
if (rc < 0) {
perror("listen");
VERIFY_NOT_REACHED();
}
}
void Service::setup_sockets()
{
for (SocketDescriptor& socket : m_sockets)
setup_socket(socket);
}
void Service::setup_notifier()
{
VERIFY(m_lazy);
VERIFY(m_socket_fd >= 0);
VERIFY(m_sockets.size() == 1);
VERIFY(!m_socket_notifier);
m_socket_notifier = Core::Notifier::construct(m_socket_fd, Core::Notifier::Event::Read, this);
m_socket_notifier = Core::Notifier::construct(m_sockets[0].fd, Core::Notifier::Event::Read, this);
m_socket_notifier->on_ready_to_read = [this] {
handle_socket_connection();
};
@ -115,10 +122,13 @@ void Service::setup_notifier()
void Service::handle_socket_connection()
{
VERIFY(m_sockets.size() == 1);
dbgln_if(SERVICE_DEBUG, "Ready to read on behalf of {}", name());
int socket_fd = m_sockets[0].fd;
if (m_accept_socket_connections) {
int accepted_fd = accept(m_socket_fd, nullptr, nullptr);
int accepted_fd = accept(socket_fd, nullptr, nullptr);
if (accepted_fd < 0) {
perror("accept");
return;
@ -128,7 +138,7 @@ void Service::handle_socket_connection()
} else {
remove_child(*m_socket_notifier);
m_socket_notifier = nullptr;
spawn(m_socket_fd);
spawn(socket_fd);
}
}
@ -139,7 +149,7 @@ void Service::activate()
if (m_lazy)
setup_notifier();
else
spawn(m_socket_fd);
spawn();
}
void Service::spawn(int socket_fd)
@ -198,12 +208,31 @@ void Service::spawn(int socket_fd)
dup2(STDIN_FILENO, STDERR_FILENO);
}
StringBuilder builder;
if (socket_fd >= 0) {
VERIFY(!m_socket_path.is_null());
VERIFY(socket_fd > 3);
dup2(socket_fd, 3);
// We were spawned by socket activation. We currently only support
// single sockets for socket activation, so make sure that's the case.
VERIFY(m_sockets.size() == 1);
int fd = dup(socket_fd);
builder.appendf("%s:%d", m_sockets[0].path.characters(), fd);
} else {
// We were spawned as a regular process, so dup every socket for this
// service and let the service know via SOCKET_TAKEOVER.
for (unsigned i = 0; i < m_sockets.size(); i++) {
SocketDescriptor& socket = m_sockets.at(i);
int new_fd = dup(socket.fd);
if (i != 0)
builder.append(" ");
builder.appendf("%s:%d", socket.path.characters(), new_fd);
}
}
if (!m_sockets.is_empty()) {
// The new descriptor is !CLOEXEC here.
setenv("SOCKET_TAKEOVER", "1", true);
setenv("SOCKET_TAKEOVER", builder.to_string().characters(), true);
}
if (m_account.has_value()) {
@ -306,22 +335,39 @@ Service::Service(const Core::ConfigFile& config, const StringView& name)
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");
String socket_entry = config.read_entry(name, "Socket");
String socket_permissions_entry = config.read_entry(name, "SocketPermissions", "0600");
// Lazy requires Socket.
VERIFY(!m_lazy || !m_socket_path.is_null());
// AcceptSocketConnections always requires Socket, Lazy, and MultiInstance.
VERIFY(!m_accept_socket_connections || (!m_socket_path.is_null() && m_lazy && m_multi_instance));
if (!socket_entry.is_null()) {
Vector<String> socket_paths = socket_entry.split(',');
Vector<String> socket_perms = socket_permissions_entry.split(',');
m_sockets.ensure_capacity(socket_paths.size());
// Need i here to iterate along with all other vectors.
for (unsigned i = 0; i < socket_paths.size(); i++) {
String& path = socket_paths.at(i);
// Socket path (plus NUL) must fit into the structs sent to the Kernel.
VERIFY(path.length() < UNIX_PATH_MAX);
// This is done so that the last permission repeats for every other
// socket. So you can define a single permission, and have it
// be applied for every socket.
mode_t permissions = strtol(socket_perms.at(min(socket_perms.size() - 1, (long unsigned)i)).characters(), nullptr, 8) & 0777;
m_sockets.empend(path, -1, permissions);
}
}
// Lazy requires Socket, but only one.
VERIFY(!m_lazy || m_sockets.size() == 1);
// AcceptSocketConnections always requires Socket (single), Lazy, and MultiInstance.
VERIFY(!m_accept_socket_connections || (m_sockets.size() == 1 && m_lazy && m_multi_instance));
// MultiInstance doesn't work with KeepAlive.
VERIFY(!m_multi_instance || !m_keep_alive);
// Socket path (plus NUL) must fit into the structs sent to the Kernel.
VERIFY(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) & 0777;
setup_socket();
}
if (is_enabled())
setup_sockets();
}
void Service::save_to(JsonObject& json)
@ -346,13 +392,20 @@ void Service::save_to(JsonObject& json)
for (String& env : m_environment)
boot_modes.append(env);
json.set("environment", environment);
JsonArray sockets;
for (SocketDescriptor &socket : m_sockets) {
JsonObject socket_obj;
socket_obj.set("path", socket.path);
socket_obj.set("permissions", socket.permissions);
sockets.append(socket);
}
json.set("sockets", sockets);
*/
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);

22
Userland/Services/SystemServer/Service.h
View file

@ -51,6 +51,17 @@ private:
void spawn(int socket_fd = -1);
/// SocketDescriptor describes the details of a single socket that was
/// requested by a service.
struct SocketDescriptor {
/// The path of the socket.
String path;
/// File descriptor of the socket. -1 if the socket hasn't been opened.
int fd { -1 };
/// File permissions of the socket.
mode_t permissions;
};
// Path to the executable. By default this is /bin/{m_name}.
String m_executable_path;
// Extra arguments, starting from argv[1], to pass when exec'ing.
@ -60,10 +71,6 @@ private:
int m_priority { 1 };
// Whether we should re-launch it if it exits.
bool m_keep_alive { false };
// Path to the socket to create and listen on on behalf of this service.
String m_socket_path;
// File system permissions for the socket.
mode_t m_socket_permissions { 0 };
// Whether we should accept connections on the socket and pass the accepted
// (and not listening) socket to the service. This requires a multi-instance
// service.
@ -80,14 +87,14 @@ private:
bool m_multi_instance { false };
// Environment variables to pass to the service.
Vector<String> m_environment;
// Socket descriptors for this service.
Vector<SocketDescriptor> m_sockets;
// The resolved user account to run this service as.
Optional<Core::Account> m_account;
// For single-instance services, PID of the running instance of this service.
pid_t m_pid { -1 };
// An open fd to the socket.
int m_socket_fd { -1 };
RefPtr<Core::Notifier> m_socket_notifier;
// Timer since we last spawned the service.
@ -96,7 +103,8 @@ private:
// times where it has exited unsuccessfully and too quickly.
int m_restart_attempts { 0 };
void setup_socket();
void setup_socket(SocketDescriptor&);
void setup_sockets();
void setup_notifier();
void handle_socket_connection();
};