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Kernel: Make sys$recvfrom() with MSG_DONTWAIT not so racy

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Instead of temporary changing the open file description's "blocking"
flag while doing a non-waiting recvfrom, we instead plumb the currently
wanted blocking behavior all the way through to the underlying socket.
This commit is contained in:
Andreas Kling 2022-08-21 16:45:42 +02:00
parent 8997c6a4d1
commit 42435ce5e4
7 changed files with 17 additions and 22 deletions
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14
Kernel/Net/IPv4Socket.cpp
View file

@ -246,7 +246,7 @@ ErrorOr<size_t> IPv4Socket::sendto(OpenFileDescription&, UserOrKernelBuffer cons
return nsent_or_error;
}
ErrorOr<size_t> IPv4Socket::receive_byte_buffered(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>)
ErrorOr<size_t> IPv4Socket::receive_byte_buffered(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, bool blocking)
{
MutexLocker locker(mutex());
@ -255,7 +255,7 @@ ErrorOr<size_t> IPv4Socket::receive_byte_buffered(OpenFileDescription& descripti
if (m_receive_buffer->is_empty()) {
if (protocol_is_disconnected())
return 0;
if (!description.is_blocking())
if (!blocking)
return set_so_error(EAGAIN);
locker.unlock();
@ -285,7 +285,7 @@ ErrorOr<size_t> IPv4Socket::receive_byte_buffered(OpenFileDescription& descripti
return nreceived_or_error;
}
ErrorOr<size_t> IPv4Socket::receive_packet_buffered(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*> addr, Userspace<socklen_t*> addr_length, Time& packet_timestamp)
ErrorOr<size_t> IPv4Socket::receive_packet_buffered(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*> addr, Userspace<socklen_t*> addr_length, Time& packet_timestamp, bool blocking)
{
MutexLocker locker(mutex());
ReceivedPacket taken_packet;
@ -296,7 +296,7 @@ ErrorOr<size_t> IPv4Socket::receive_packet_buffered(OpenFileDescription& descrip
// But if so, we still need to deliver at least one EOF read to userspace.. right?
if (protocol_is_disconnected())
return 0;
if (!description.is_blocking())
if (!blocking)
return set_so_error(EAGAIN);
}
@ -380,7 +380,7 @@ ErrorOr<size_t> IPv4Socket::receive_packet_buffered(OpenFileDescription& descrip
return protocol_receive(packet->data->bytes(), buffer, buffer_length, flags);
}
ErrorOr<size_t> IPv4Socket::recvfrom(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*> user_addr, Userspace<socklen_t*> user_addr_length, Time& packet_timestamp)
ErrorOr<size_t> IPv4Socket::recvfrom(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*> user_addr, Userspace<socklen_t*> user_addr_length, Time& packet_timestamp, bool blocking)
{
if (user_addr_length) {
socklen_t addr_length;
@ -398,9 +398,9 @@ ErrorOr<size_t> IPv4Socket::recvfrom(OpenFileDescription& description, UserOrKer
ErrorOr<size_t> nreceived = 0;
if (buffer_mode() == BufferMode::Bytes)
nreceived = receive_byte_buffered(description, offset_buffer, offset_buffer_length, flags, user_addr, user_addr_length);
nreceived = receive_byte_buffered(description, offset_buffer, offset_buffer_length, flags, user_addr, user_addr_length, blocking);
else
nreceived = receive_packet_buffered(description, offset_buffer, offset_buffer_length, flags, user_addr, user_addr_length, packet_timestamp);
nreceived = receive_packet_buffered(description, offset_buffer, offset_buffer_length, flags, user_addr, user_addr_length, packet_timestamp, blocking);
if (nreceived.is_error())
total_nreceived = nreceived;

6
Kernel/Net/IPv4Socket.h
View file

@ -40,7 +40,7 @@ public:
virtual bool can_read(OpenFileDescription const&, u64) const override;
virtual bool can_write(OpenFileDescription const&, u64) const override;
virtual ErrorOr<size_t> sendto(OpenFileDescription&, UserOrKernelBuffer const&, size_t, int, Userspace<sockaddr const*>, socklen_t) override;
virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&) override;
virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&, bool blocking) override;
virtual ErrorOr<void> setsockopt(int level, int option, Userspace<void const*>, socklen_t) override;
virtual ErrorOr<void> getsockopt(OpenFileDescription&, int level, int option, Userspace<void*>, Userspace<socklen_t*>) override;
@ -98,8 +98,8 @@ protected:
private:
virtual bool is_ipv4() const override { return true; }
ErrorOr<size_t> receive_byte_buffered(OpenFileDescription&, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>);
ErrorOr<size_t> receive_packet_buffered(OpenFileDescription&, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&);
ErrorOr<size_t> receive_byte_buffered(OpenFileDescription&, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, bool blocking);
ErrorOr<size_t> receive_packet_buffered(OpenFileDescription&, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&, bool blocking);
void set_can_read(bool);

4
Kernel/Net/LocalSocket.cpp
View file

@ -334,12 +334,12 @@ DoubleBuffer* LocalSocket::send_buffer_for(OpenFileDescription& description)
return nullptr;
}
ErrorOr<size_t> LocalSocket::recvfrom(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_size, int, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&)
ErrorOr<size_t> LocalSocket::recvfrom(OpenFileDescription& description, UserOrKernelBuffer& buffer, size_t buffer_size, int, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&, bool blocking)
{
auto* socket_buffer = receive_buffer_for(description);
if (!socket_buffer)
return set_so_error(EINVAL);
if (!description.is_blocking()) {
if (!blocking) {
if (socket_buffer->is_empty()) {
if (!has_attached_peer(description))
return 0;

2
Kernel/Net/LocalSocket.h
View file

@ -46,7 +46,7 @@ public:
virtual bool can_read(OpenFileDescription const&, u64) const override;
virtual bool can_write(OpenFileDescription const&, u64) const override;
virtual ErrorOr<size_t> sendto(OpenFileDescription&, UserOrKernelBuffer const&, size_t, int, Userspace<sockaddr const*>, socklen_t) override;
virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&) override;
virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&, bool blocking) override;
virtual ErrorOr<void> getsockopt(OpenFileDescription&, int level, int option, Userspace<void*>, Userspace<socklen_t*>) override;
virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;
virtual ErrorOr<void> chown(Credentials const&, OpenFileDescription&, UserID, GroupID) override;

2
Kernel/Net/Socket.cpp
View file

@ -242,7 +242,7 @@ ErrorOr<size_t> Socket::read(OpenFileDescription& description, u64, UserOrKernel
if (is_shut_down_for_reading())
return 0;
Time t {};
return recvfrom(description, buffer, size, 0, {}, 0, t);
return recvfrom(description, buffer, size, 0, {}, 0, t, description.is_blocking());
}
ErrorOr<size_t> Socket::write(OpenFileDescription& description, u64, UserOrKernelBuffer const& data, size_t size)

2
Kernel/Net/Socket.h
View file

@ -80,7 +80,7 @@ public:
virtual bool is_local() const { return false; }
virtual bool is_ipv4() const { return false; }
virtual ErrorOr<size_t> sendto(OpenFileDescription&, UserOrKernelBuffer const&, size_t, int flags, Userspace<sockaddr const*>, socklen_t) = 0;
virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&) = 0;
virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, Time&, bool blocking) = 0;
virtual ErrorOr<void> setsockopt(int level, int option, Userspace<void const*>, socklen_t);
virtual ErrorOr<void> getsockopt(OpenFileDescription&, int level, int option, Userspace<void*>, Userspace<socklen_t*>);

9
Kernel/Syscalls/socket.cpp
View file

@ -241,15 +241,10 @@ ErrorOr<FlatPtr> Process::sys$recvmsg(int sockfd, Userspace<struct msghdr*> user
if (socket.is_shut_down_for_reading())
return 0;
bool original_blocking = description->is_blocking();
if (flags & MSG_DONTWAIT)
description->set_blocking(false);
auto data_buffer = TRY(UserOrKernelBuffer::for_user_buffer((u8*)iovs[0].iov_base, iovs[0].iov_len));
Time timestamp {};
auto result = socket.recvfrom(*description, data_buffer, iovs[0].iov_len, flags, user_addr, user_addr_length, timestamp);
if (flags & MSG_DONTWAIT)
description->set_blocking(original_blocking);
bool blocking = (flags & MSG_DONTWAIT) ? false : description->is_blocking();
auto result = socket.recvfrom(*description, data_buffer, iovs[0].iov_len, flags, user_addr, user_addr_length, timestamp, blocking);
if (result.is_error())
return result.release_error();