Skip to content

Commit

Permalink
Kernel: Migrate TCP socket tables locking to ProtectedValue
Browse files Browse the repository at this point in the history 
Note: TCPSocket::create_client() has a dubious locking process where
the sockets by tuple table is first shared lock to check if the socket
exists and bail out if it does, then unlocks, then exclusively locks to
add the tuple. There could be a race condition where two client
creation requests for the same tuple happen at the same time and both
cleared the shared lock check. When in doubt, lock exclusively the
whole time.
  • Loading branch information
@boricj @awesomekling
boricj authored and awesomekling committed Aug 7, 2021
1 parent 583abc2 commit 9216c72
Show file tree
Hide file tree
Showing 3 changed files with 90 additions and 85 deletions.
9 changes: 4 additions & 5 deletions Kernel/Net/NetworkTask.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@

#include <Kernel/Debug.h>
#include <Kernel/Locking/Mutex.h>
#include <Kernel/Locking/ProtectedValue.h>
#include <Kernel/Net/ARP.h>
#include <Kernel/Net/EtherType.h>
#include <Kernel/Net/EthernetFrameHeader.h>
Expand Down Expand Up @@ -639,11 +640,9 @@ void retransmit_tcp_packets()
// We must keep the sockets alive until after we've unlocked the hash table
// in case retransmit_packets() realizes that it wants to close the socket.
NonnullRefPtrVector<TCPSocket, 16> sockets;
{
MutexLocker locker(TCPSocket::sockets_for_retransmit().lock(), LockMode::Shared);
for (auto& socket : TCPSocket::sockets_for_retransmit().resource())
sockets.append(*socket);
}
TCPSocket::sockets_for_retransmit().for_each_shared([&](const auto& socket) {
sockets.append(*socket);
});

for (auto& socket : sockets) {
MutexLocker socket_locker(socket.lock());
Expand Down
158 changes: 82 additions & 76 deletions Kernel/Net/TCPSocket.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@
#include <Kernel/Debug.h>
#include <Kernel/Devices/RandomDevice.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Locking/Lockable.h>
#include <Kernel/Locking/ProtectedValue.h>
#include <Kernel/Net/EthernetFrameHeader.h>
#include <Kernel/Net/IPv4.h>
#include <Kernel/Net/NetworkAdapter.h>
Expand All @@ -24,9 +24,9 @@ namespace Kernel {

void TCPSocket::for_each(Function<void(const TCPSocket&)> callback)
{
MutexLocker locker(sockets_by_tuple().lock(), Mutex::Mode::Shared);
for (auto& it : sockets_by_tuple().resource())
sockets_by_tuple().for_each_shared([&](const auto& it) {
callback(*it.value);
});
}

void TCPSocket::set_state(State new_state)
Expand All @@ -42,8 +42,9 @@ void TCPSocket::set_state(State new_state)
m_role = Role::Connected;

if (new_state == State::Closed) {
MutexLocker locker(closing_sockets().lock());
closing_sockets().resource().remove(tuple());
closing_sockets().with_exclusive([&](auto& table) {
table.remove(tuple());
});

if (m_originator)
release_to_originator();
Expand All @@ -53,71 +54,68 @@ void TCPSocket::set_state(State new_state)
evaluate_block_conditions();
}

static AK::Singleton<Lockable<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>> s_socket_closing;
static AK::Singleton<ProtectedValue<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>> s_socket_closing;

Lockable<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>& TCPSocket::closing_sockets()
ProtectedValue<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>& TCPSocket::closing_sockets()
{
return *s_socket_closing;
}

static AK::Singleton<Lockable<HashMap<IPv4SocketTuple, TCPSocket*>>> s_socket_tuples;
static AK::Singleton<ProtectedValue<HashMap<IPv4SocketTuple, TCPSocket*>>> s_socket_tuples;

Lockable<HashMap<IPv4SocketTuple, TCPSocket*>>& TCPSocket::sockets_by_tuple()
ProtectedValue<HashMap<IPv4SocketTuple, TCPSocket*>>& TCPSocket::sockets_by_tuple()
{
return *s_socket_tuples;
}

RefPtr<TCPSocket> TCPSocket::from_tuple(const IPv4SocketTuple& tuple)
{
MutexLocker locker(sockets_by_tuple().lock(), Mutex::Mode::Shared);
return sockets_by_tuple().with_shared([&](const auto& table) -> RefPtr<TCPSocket> {
auto exact_match = table.get(tuple);
if (exact_match.has_value())
return { *exact_match.value() };

auto exact_match = sockets_by_tuple().resource().get(tuple);
if (exact_match.has_value())
return { *exact_match.value() };
auto address_tuple = IPv4SocketTuple(tuple.local_address(), tuple.local_port(), IPv4Address(), 0);
auto address_match = table.get(address_tuple);
if (address_match.has_value())
return { *address_match.value() };

auto address_tuple = IPv4SocketTuple(tuple.local_address(), tuple.local_port(), IPv4Address(), 0);
auto address_match = sockets_by_tuple().resource().get(address_tuple);
if (address_match.has_value())
return { *address_match.value() };
auto wildcard_tuple = IPv4SocketTuple(IPv4Address(), tuple.local_port(), IPv4Address(), 0);
auto wildcard_match = table.get(wildcard_tuple);
if (wildcard_match.has_value())
return { *wildcard_match.value() };

auto wildcard_tuple = IPv4SocketTuple(IPv4Address(), tuple.local_port(), IPv4Address(), 0);
auto wildcard_match = sockets_by_tuple().resource().get(wildcard_tuple);
if (wildcard_match.has_value())
return { *wildcard_match.value() };

return {};
return {};
});
}
RefPtr<TCPSocket> TCPSocket::create_client(const IPv4Address& new_local_address, u16 new_local_port, const IPv4Address& new_peer_address, u16 new_peer_port)
{
auto tuple = IPv4SocketTuple(new_local_address, new_local_port, new_peer_address, new_peer_port);

{
MutexLocker locker(sockets_by_tuple().lock(), Mutex::Mode::Shared);
if (sockets_by_tuple().resource().contains(tuple))
return sockets_by_tuple().with_exclusive([&](auto& table) -> RefPtr<TCPSocket> {
if (table.contains(tuple))
return {};
}

auto receive_buffer = create_receive_buffer();
if (!receive_buffer)
return {};
auto result = TCPSocket::create(protocol(), receive_buffer.release_nonnull());
if (result.is_error())
return {};
auto receive_buffer = create_receive_buffer();
if (!receive_buffer)
return {};
auto result = TCPSocket::create(protocol(), receive_buffer.release_nonnull());
if (result.is_error())
return {};

auto client = result.release_value();
client->set_setup_state(SetupState::InProgress);
client->set_local_address(new_local_address);
client->set_local_port(new_local_port);
client->set_peer_address(new_peer_address);
client->set_peer_port(new_peer_port);
client->set_direction(Direction::Incoming);
client->set_originator(*this);
auto client = result.release_value();
client->set_setup_state(SetupState::InProgress);
client->set_local_address(new_local_address);
client->set_local_port(new_local_port);
client->set_peer_address(new_peer_address);
client->set_peer_port(new_peer_port);
client->set_direction(Direction::Incoming);
client->set_originator(*this);

MutexLocker locker(sockets_by_tuple().lock());
m_pending_release_for_accept.set(tuple, client);
sockets_by_tuple().resource().set(tuple, client);
m_pending_release_for_accept.set(tuple, client);
table.set(tuple, client);

return client;
return { move(client) };
});
}

void TCPSocket::release_to_originator()
Expand All @@ -143,8 +141,9 @@ TCPSocket::TCPSocket(int protocol, NonnullOwnPtr<DoubleBuffer> receive_buffer, O

TCPSocket::~TCPSocket()
{
MutexLocker locker(sockets_by_tuple().lock());
sockets_by_tuple().resource().remove(tuple());
sockets_by_tuple().with_exclusive([&](auto& table) {
table.remove(tuple());
});

dequeue_for_retransmit();

Expand Down Expand Up @@ -378,10 +377,14 @@ KResult TCPSocket::protocol_bind()
KResult TCPSocket::protocol_listen(bool did_allocate_port)
{
if (!did_allocate_port) {
MutexLocker socket_locker(sockets_by_tuple().lock());
if (sockets_by_tuple().resource().contains(tuple()))
bool ok = sockets_by_tuple().with_exclusive([&](auto& table) -> bool {
if (table.contains(tuple()))
return false;
table.set(tuple(), this);
return true;
});
if (!ok)
return EADDRINUSE;
sockets_by_tuple().resource().set(tuple(), this);
}

set_direction(Direction::Passive);
Expand Down Expand Up @@ -443,23 +446,24 @@ KResultOr<u16> TCPSocket::protocol_allocate_local_port()
constexpr u16 ephemeral_port_range_size = last_ephemeral_port - first_ephemeral_port;
u16 first_scan_port = first_ephemeral_port + get_good_random<u16>() % ephemeral_port_range_size;

MutexLocker locker(sockets_by_tuple().lock());
for (u16 port = first_scan_port;;) {
IPv4SocketTuple proposed_tuple(local_address(), port, peer_address(), peer_port());
return sockets_by_tuple().with_exclusive([&](auto& table) -> KResultOr<u16> {
for (u16 port = first_scan_port;;) {
IPv4SocketTuple proposed_tuple(local_address(), port, peer_address(), peer_port());

auto it = sockets_by_tuple().resource().find(proposed_tuple);
if (it == sockets_by_tuple().resource().end()) {
set_local_port(port);
sockets_by_tuple().resource().set(proposed_tuple, this);
return port;
auto it = table.find(proposed_tuple);
if (it == table.end()) {
set_local_port(port);
table.set(proposed_tuple, this);
return port;
}
++port;
if (port > last_ephemeral_port)
port = first_ephemeral_port;
if (port == first_scan_port)
break;
}
++port;
if (port > last_ephemeral_port)
port = first_ephemeral_port;
if (port == first_scan_port)
break;
}
return EADDRINUSE;
return EADDRINUSE;
});
}

bool TCPSocket::protocol_is_disconnected() const
Expand Down Expand Up @@ -499,30 +503,32 @@ KResult TCPSocket::close()
set_state(State::LastAck);
}

if (state() != State::Closed && state() != State::Listen) {
MutexLocker locker(closing_sockets().lock());
closing_sockets().resource().set(tuple(), *this);
}
if (state() != State::Closed && state() != State::Listen)
closing_sockets().with_exclusive([&](auto& table) {
table.set(tuple(), *this);
});
return result;
}

static AK::Singleton<Lockable<HashTable<TCPSocket*>>> s_sockets_for_retransmit;
static AK::Singleton<ProtectedValue<HashTable<TCPSocket*>>> s_sockets_for_retransmit;

Lockable<HashTable<TCPSocket*>>& TCPSocket::sockets_for_retransmit()
ProtectedValue<HashTable<TCPSocket*>>& TCPSocket::sockets_for_retransmit()
{
return *s_sockets_for_retransmit;
}

void TCPSocket::enqueue_for_retransmit()
{
MutexLocker locker(sockets_for_retransmit().lock());
sockets_for_retransmit().resource().set(this);
sockets_for_retransmit().with_exclusive([&](auto& table) {
table.set(this);
});
}

void TCPSocket::dequeue_for_retransmit()
{
MutexLocker locker(sockets_for_retransmit().lock());
sockets_for_retransmit().resource().remove(this);
sockets_for_retransmit().with_exclusive([&](auto& table) {
table.remove(this);
});
}

void TCPSocket::retransmit_packets()
Expand Down
8 changes: 4 additions & 4 deletions Kernel/Net/TCPSocket.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@
#include <AK/SinglyLinkedList.h>
#include <AK/WeakPtr.h>
#include <Kernel/KResult.h>
#include <Kernel/Locking/Lockable.h>
#include <Kernel/Locking/ProtectedValue.h>
#include <Kernel/Net/IPv4Socket.h>

namespace Kernel {
Expand Down Expand Up @@ -142,18 +142,18 @@ class TCPSocket final : public IPv4Socket {

bool should_delay_next_ack() const;

static Lockable<HashMap<IPv4SocketTuple, TCPSocket*>>& sockets_by_tuple();
static ProtectedValue<HashMap<IPv4SocketTuple, TCPSocket*>>& sockets_by_tuple();
static RefPtr<TCPSocket> from_tuple(const IPv4SocketTuple& tuple);

static Lockable<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>& closing_sockets();
static ProtectedValue<HashMap<IPv4SocketTuple, RefPtr<TCPSocket>>>& closing_sockets();

RefPtr<TCPSocket> create_client(const IPv4Address& local_address, u16 local_port, const IPv4Address& peer_address, u16 peer_port);
void set_originator(TCPSocket& originator) { m_originator = originator; }
bool has_originator() { return !!m_originator; }
void release_to_originator();
void release_for_accept(RefPtr<TCPSocket>);

static Lockable<HashTable<TCPSocket*>>& sockets_for_retransmit();
static ProtectedValue<HashTable<TCPSocket*>>& sockets_for_retransmit();
void retransmit_packets();

virtual KResult close() override;
Expand Down

0 comments on commit 9216c72

Please sign in to comment.