diff --git a/Kernel/Console.cpp b/Kernel/Console.cpp
index c4054189420..0fd10a34fa0 100644
--- a/Kernel/Console.cpp
+++ b/Kernel/Console.cpp
@@ -28,7 +28,7 @@ Console::~Console()
 {
 }
 
-bool Console::can_read(FileDescription&) const
+bool Console::can_read(const FileDescription&) const
 {
     return false;
 }
diff --git a/Kernel/Console.h b/Kernel/Console.h
index a9c89f5df7b..e7e0b92d319 100644
--- a/Kernel/Console.h
+++ b/Kernel/Console.h
@@ -20,8 +20,8 @@ public:
     virtual ~Console() override;
 
     // ^CharacterDevice
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override { return true; }
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
     virtual const char* class_name() const override { return "Console"; }
diff --git a/Kernel/Devices/BXVGADevice.cpp b/Kernel/Devices/BXVGADevice.cpp
index 40e7569a52b..5c277075d17 100644
--- a/Kernel/Devices/BXVGADevice.cpp
+++ b/Kernel/Devices/BXVGADevice.cpp
@@ -150,12 +150,12 @@ int BXVGADevice::ioctl(FileDescription&, unsigned request, unsigned arg)
     };
 }
 
-bool BXVGADevice::can_read(FileDescription&) const
+bool BXVGADevice::can_read(const FileDescription&) const
 {
     ASSERT_NOT_REACHED();
 }
 
-bool BXVGADevice::can_write(FileDescription&) const
+bool BXVGADevice::can_write(const FileDescription&) const
 {
     ASSERT_NOT_REACHED();
 }
diff --git a/Kernel/Devices/BXVGADevice.h b/Kernel/Devices/BXVGADevice.h
index 908bfd3bdb0..465203a9a8d 100644
--- a/Kernel/Devices/BXVGADevice.h
+++ b/Kernel/Devices/BXVGADevice.h
@@ -17,8 +17,8 @@ public:
 
 private:
     virtual const char* class_name() const override { return "BXVGA"; }
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
 
diff --git a/Kernel/Devices/DebugLogDevice.h b/Kernel/Devices/DebugLogDevice.h
index 1c3296a2861..50142037106 100644
--- a/Kernel/Devices/DebugLogDevice.h
+++ b/Kernel/Devices/DebugLogDevice.h
@@ -11,7 +11,7 @@ private:
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override { return 0; }
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override { return true; }
-    virtual bool can_read(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
     virtual const char* class_name() const override { return "DebugLogDevice"; }
 };
diff --git a/Kernel/Devices/DiskPartition.h b/Kernel/Devices/DiskPartition.h
index 6ad35eb2c4b..0c2ea477d4c 100644
--- a/Kernel/Devices/DiskPartition.h
+++ b/Kernel/Devices/DiskPartition.h
@@ -15,9 +15,9 @@ public:
 
     // ^BlockDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override { return 0; }
-    virtual bool can_read(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override { return 0; }
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
 private:
     virtual const char* class_name() const override;
diff --git a/Kernel/Devices/FloppyDiskDevice.h b/Kernel/Devices/FloppyDiskDevice.h
index 0b35f47fb7e..7afc0e49f1d 100644
--- a/Kernel/Devices/FloppyDiskDevice.h
+++ b/Kernel/Devices/FloppyDiskDevice.h
@@ -143,9 +143,9 @@ public:
 
     // ^BlockDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override { return 0; }
-    virtual bool can_read(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override { return 0; }
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
 protected:
     explicit FloppyDiskDevice(DriveType);
diff --git a/Kernel/Devices/FullDevice.cpp b/Kernel/Devices/FullDevice.cpp
index b76a79d5bf2..55a985ad4a5 100644
--- a/Kernel/Devices/FullDevice.cpp
+++ b/Kernel/Devices/FullDevice.cpp
@@ -12,7 +12,7 @@ FullDevice::~FullDevice()
 {
 }
 
-bool FullDevice::can_read(FileDescription&) const
+bool FullDevice::can_read(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/Devices/FullDevice.h b/Kernel/Devices/FullDevice.h
index 9ba58161f16..14d0bbb6a0e 100644
--- a/Kernel/Devices/FullDevice.h
+++ b/Kernel/Devices/FullDevice.h
@@ -12,7 +12,7 @@ private:
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override { return true; }
     virtual const char* class_name() const override { return "FullDevice"; }
 };
diff --git a/Kernel/Devices/KeyboardDevice.cpp b/Kernel/Devices/KeyboardDevice.cpp
index 37356d7bc99..cc64d85a6d0 100644
--- a/Kernel/Devices/KeyboardDevice.cpp
+++ b/Kernel/Devices/KeyboardDevice.cpp
@@ -368,7 +368,7 @@ KeyboardDevice::~KeyboardDevice()
 {
 }
 
-bool KeyboardDevice::can_read(FileDescription&) const
+bool KeyboardDevice::can_read(const FileDescription&) const
 {
     return !m_queue.is_empty();
 }
diff --git a/Kernel/Devices/KeyboardDevice.h b/Kernel/Devices/KeyboardDevice.h
index 1ac2bcf8418..7ba84937449 100644
--- a/Kernel/Devices/KeyboardDevice.h
+++ b/Kernel/Devices/KeyboardDevice.h
@@ -24,9 +24,9 @@ public:
 
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8* buffer, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
     virtual ssize_t write(FileDescription&, const u8* buffer, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
 private:
     // ^IRQHandler
diff --git a/Kernel/Devices/MBVGADevice.cpp b/Kernel/Devices/MBVGADevice.cpp
index d65524c9736..2b4554e7e5c 100644
--- a/Kernel/Devices/MBVGADevice.cpp
+++ b/Kernel/Devices/MBVGADevice.cpp
@@ -82,12 +82,12 @@ int MBVGADevice::ioctl(FileDescription&, unsigned request, unsigned arg)
     };
 }
 
-bool MBVGADevice::can_read(FileDescription&) const
+bool MBVGADevice::can_read(const FileDescription&) const
 {
     ASSERT_NOT_REACHED();
 }
 
-bool MBVGADevice::can_write(FileDescription&) const
+bool MBVGADevice::can_write(const FileDescription&) const
 {
     ASSERT_NOT_REACHED();
 }
diff --git a/Kernel/Devices/MBVGADevice.h b/Kernel/Devices/MBVGADevice.h
index 2c46b8296fa..a7980a1fcb3 100644
--- a/Kernel/Devices/MBVGADevice.h
+++ b/Kernel/Devices/MBVGADevice.h
@@ -17,8 +17,8 @@ public:
 
 private:
     virtual const char* class_name() const override { return "MBVGA"; }
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
 
diff --git a/Kernel/Devices/NullDevice.cpp b/Kernel/Devices/NullDevice.cpp
index b4fa429219f..e91a3cd68c8 100644
--- a/Kernel/Devices/NullDevice.cpp
+++ b/Kernel/Devices/NullDevice.cpp
@@ -20,7 +20,7 @@ NullDevice::~NullDevice()
 {
 }
 
-bool NullDevice::can_read(FileDescription&) const
+bool NullDevice::can_read(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/Devices/NullDevice.h b/Kernel/Devices/NullDevice.h
index 822e61508db..84e0a8fc020 100644
--- a/Kernel/Devices/NullDevice.h
+++ b/Kernel/Devices/NullDevice.h
@@ -14,7 +14,7 @@ private:
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override { return true; }
-    virtual bool can_read(FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override;
     virtual const char* class_name() const override { return "NullDevice"; }
 };
diff --git a/Kernel/Devices/PATADiskDevice.h b/Kernel/Devices/PATADiskDevice.h
index 0dbf1b4afe4..56beb60f881 100644
--- a/Kernel/Devices/PATADiskDevice.h
+++ b/Kernel/Devices/PATADiskDevice.h
@@ -36,9 +36,9 @@ public:
 
     // ^BlockDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override { return 0; }
-    virtual bool can_read(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override { return 0; }
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
 protected:
     explicit PATADiskDevice(PATAChannel&, DriveType, int, int);
diff --git a/Kernel/Devices/PS2MouseDevice.cpp b/Kernel/Devices/PS2MouseDevice.cpp
index 2fa2822df04..2cacdc85d4f 100644
--- a/Kernel/Devices/PS2MouseDevice.cpp
+++ b/Kernel/Devices/PS2MouseDevice.cpp
@@ -255,7 +255,7 @@ u8 PS2MouseDevice::mouse_read()
     return IO::in8(I8042_BUFFER);
 }
 
-bool PS2MouseDevice::can_read(FileDescription&) const
+bool PS2MouseDevice::can_read(const FileDescription&) const
 {
     return !m_queue.is_empty();
 }
diff --git a/Kernel/Devices/PS2MouseDevice.h b/Kernel/Devices/PS2MouseDevice.h
index c16cb6eb67b..180fae48f13 100644
--- a/Kernel/Devices/PS2MouseDevice.h
+++ b/Kernel/Devices/PS2MouseDevice.h
@@ -14,10 +14,10 @@ public:
     static PS2MouseDevice& the();
 
     // ^CharacterDevice
-    virtual bool can_read(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
 private:
     // ^IRQHandler
diff --git a/Kernel/Devices/RandomDevice.cpp b/Kernel/Devices/RandomDevice.cpp
index 5fcd4ace1a3..9df6a2c23ac 100644
--- a/Kernel/Devices/RandomDevice.cpp
+++ b/Kernel/Devices/RandomDevice.cpp
@@ -26,7 +26,7 @@ static void mysrand(unsigned seed)
 }
 #endif
 
-bool RandomDevice::can_read(FileDescription&) const
+bool RandomDevice::can_read(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/Devices/RandomDevice.h b/Kernel/Devices/RandomDevice.h
index b1a3e7b0d4e..a11589d310d 100644
--- a/Kernel/Devices/RandomDevice.h
+++ b/Kernel/Devices/RandomDevice.h
@@ -14,7 +14,7 @@ private:
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override { return true; }
     virtual const char* class_name() const override { return "RandomDevice"; }
 };
diff --git a/Kernel/Devices/SB16.cpp b/Kernel/Devices/SB16.cpp
index e376b17f7e0..0ec3b382450 100644
--- a/Kernel/Devices/SB16.cpp
+++ b/Kernel/Devices/SB16.cpp
@@ -84,7 +84,7 @@ void SB16::initialize()
     enable_irq();
 }
 
-bool SB16::can_read(FileDescription&) const
+bool SB16::can_read(const FileDescription&) const
 {
     return false;
 }
diff --git a/Kernel/Devices/SB16.h b/Kernel/Devices/SB16.h
index d91de1c2d4d..63d54569b86 100644
--- a/Kernel/Devices/SB16.h
+++ b/Kernel/Devices/SB16.h
@@ -17,10 +17,10 @@ public:
     static SB16& the();
 
     // ^CharacterDevice
-    virtual bool can_read(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
 private:
     // ^IRQHandler
diff --git a/Kernel/Devices/SerialDevice.cpp b/Kernel/Devices/SerialDevice.cpp
index 7f555ae8072..95183915cb4 100644
--- a/Kernel/Devices/SerialDevice.cpp
+++ b/Kernel/Devices/SerialDevice.cpp
@@ -12,7 +12,7 @@ SerialDevice::~SerialDevice()
 {
 }
 
-bool SerialDevice::can_read(FileDescription&) const
+bool SerialDevice::can_read(const FileDescription&) const
 {
     return (get_line_status() & DataReady) != 0;
 }
@@ -30,7 +30,7 @@ ssize_t SerialDevice::read(FileDescription&, u8* buffer, ssize_t size)
     return 1;
 }
 
-bool SerialDevice::can_write(FileDescription&) const
+bool SerialDevice::can_write(const FileDescription&) const
 {
     return (get_line_status() & EmptyTransmitterHoldingRegister) != 0;
 }
diff --git a/Kernel/Devices/SerialDevice.h b/Kernel/Devices/SerialDevice.h
index 78706e1be84..d6ac9e0cfcf 100644
--- a/Kernel/Devices/SerialDevice.h
+++ b/Kernel/Devices/SerialDevice.h
@@ -12,9 +12,9 @@ public:
     virtual ~SerialDevice() override;
 
     // ^CharacterDevice
-    virtual bool can_read(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
 
     enum InterruptEnable {
diff --git a/Kernel/Devices/ZeroDevice.cpp b/Kernel/Devices/ZeroDevice.cpp
index cfb3e3b4c36..352541a3cc2 100644
--- a/Kernel/Devices/ZeroDevice.cpp
+++ b/Kernel/Devices/ZeroDevice.cpp
@@ -11,7 +11,7 @@ ZeroDevice::~ZeroDevice()
 {
 }
 
-bool ZeroDevice::can_read(FileDescription&) const
+bool ZeroDevice::can_read(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/Devices/ZeroDevice.h b/Kernel/Devices/ZeroDevice.h
index 42ceff3abe9..f6df9bf0a05 100644
--- a/Kernel/Devices/ZeroDevice.h
+++ b/Kernel/Devices/ZeroDevice.h
@@ -12,7 +12,7 @@ private:
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override { return true; }
     virtual const char* class_name() const override { return "ZeroDevice"; }
 };
diff --git a/Kernel/FileSystem/FIFO.cpp b/Kernel/FileSystem/FIFO.cpp
index 6fc77a7b2bf..390a05d16fd 100644
--- a/Kernel/FileSystem/FIFO.cpp
+++ b/Kernel/FileSystem/FIFO.cpp
@@ -83,12 +83,12 @@ void FIFO::detach(Direction direction)
     }
 }
 
-bool FIFO::can_read(FileDescription&) const
+bool FIFO::can_read(const FileDescription&) const
 {
     return !m_buffer.is_empty() || !m_writers;
 }
 
-bool FIFO::can_write(FileDescription&) const
+bool FIFO::can_write(const FileDescription&) const
 {
     return m_buffer.bytes_in_write_buffer() < 4096 || !m_readers;
 }
diff --git a/Kernel/FileSystem/FIFO.h b/Kernel/FileSystem/FIFO.h
index 77c5427ba2e..2869545fe66 100644
--- a/Kernel/FileSystem/FIFO.h
+++ b/Kernel/FileSystem/FIFO.h
@@ -30,8 +30,8 @@ private:
     // ^File
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual String absolute_path(const FileDescription&) const override;
     virtual const char* class_name() const override { return "FIFO"; }
     virtual bool is_fifo() const override { return true; }
diff --git a/Kernel/FileSystem/File.h b/Kernel/FileSystem/File.h
index 4f838f93351..36d468f4421 100644
--- a/Kernel/FileSystem/File.h
+++ b/Kernel/FileSystem/File.h
@@ -46,8 +46,8 @@ public:
     virtual KResultOr<NonnullRefPtr<FileDescription>> open(int options);
     virtual void close();
 
-    virtual bool can_read(FileDescription&) const = 0;
-    virtual bool can_write(FileDescription&) const = 0;
+    virtual bool can_read(const FileDescription&) const = 0;
+    virtual bool can_write(const FileDescription&) const = 0;
 
     virtual ssize_t read(FileDescription&, u8*, ssize_t) = 0;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) = 0;
diff --git a/Kernel/FileSystem/FileDescription.cpp b/Kernel/FileSystem/FileDescription.cpp
index 3b99620018b..cb5e6c27175 100644
--- a/Kernel/FileSystem/FileDescription.cpp
+++ b/Kernel/FileSystem/FileDescription.cpp
@@ -121,14 +121,12 @@ ssize_t FileDescription::write(const u8* data, ssize_t size)
 
 bool FileDescription::can_write() const
 {
-    // FIXME: Remove this const_cast.
-    return m_file->can_write(const_cast<FileDescription&>(*this));
+    return m_file->can_write(*this);
 }
 
 bool FileDescription::can_read() const
 {
-    // FIXME: Remove this const_cast.
-    return m_file->can_read(const_cast<FileDescription&>(*this));
+    return m_file->can_read(*this);
 }
 
 ByteBuffer FileDescription::read_entire_file()
diff --git a/Kernel/FileSystem/InodeFile.h b/Kernel/FileSystem/InodeFile.h
index b2ee30c1969..c7def9be459 100644
--- a/Kernel/FileSystem/InodeFile.h
+++ b/Kernel/FileSystem/InodeFile.h
@@ -16,8 +16,8 @@ public:
     const Inode& inode() const { return *m_inode; }
     Inode& inode() { return *m_inode; }
 
-    virtual bool can_read(FileDescription&) const override { return true; }
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
diff --git a/Kernel/FileSystem/InodeWatcher.cpp b/Kernel/FileSystem/InodeWatcher.cpp
index 9a5e3840959..797683535c9 100644
--- a/Kernel/FileSystem/InodeWatcher.cpp
+++ b/Kernel/FileSystem/InodeWatcher.cpp
@@ -18,12 +18,12 @@ InodeWatcher::~InodeWatcher()
         safe_inode->unregister_watcher({}, *this);
 }
 
-bool InodeWatcher::can_read(FileDescription&) const
+bool InodeWatcher::can_read(const FileDescription&) const
 {
     return !m_queue.is_empty() || !m_inode;
 }
 
-bool InodeWatcher::can_write(FileDescription&) const
+bool InodeWatcher::can_write(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/FileSystem/InodeWatcher.h b/Kernel/FileSystem/InodeWatcher.h
index e4091429f24..62cf5ee9153 100644
--- a/Kernel/FileSystem/InodeWatcher.h
+++ b/Kernel/FileSystem/InodeWatcher.h
@@ -21,8 +21,8 @@ public:
         Type type { Type::Invalid };
     };
 
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
     virtual String absolute_path(const FileDescription&) const override;
diff --git a/Kernel/FileSystem/SharedMemory.h b/Kernel/FileSystem/SharedMemory.h
index d7848b97983..f81c3296958 100644
--- a/Kernel/FileSystem/SharedMemory.h
+++ b/Kernel/FileSystem/SharedMemory.h
@@ -24,8 +24,8 @@ public:
 
 private:
     // ^File
-    virtual bool can_read(FileDescription&) const override { return true; }
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
     virtual int read(FileDescription&, u8*, int) override;
     virtual int write(FileDescription&, const u8*, int) override;
     virtual String absolute_path(const FileDescription&) const override;
diff --git a/Kernel/Net/IPv4Socket.cpp b/Kernel/Net/IPv4Socket.cpp
index 1385ae80b93..2e4dd1344bc 100644
--- a/Kernel/Net/IPv4Socket.cpp
+++ b/Kernel/Net/IPv4Socket.cpp
@@ -144,7 +144,7 @@ void IPv4Socket::detach(FileDescription&)
 {
 }
 
-bool IPv4Socket::can_read(FileDescription&) const
+bool IPv4Socket::can_read(const FileDescription&) const
 {
     if (m_role == Role::Listener)
         return can_accept();
@@ -153,7 +153,7 @@ bool IPv4Socket::can_read(FileDescription&) const
     return m_can_read;
 }
 
-bool IPv4Socket::can_write(FileDescription&) const
+bool IPv4Socket::can_write(const FileDescription&) const
 {
     return is_connected();
 }
@@ -282,9 +282,13 @@ ssize_t IPv4Socket::recvfrom(FileDescription& description, void* buffer, size_t
     return protocol_receive(packet.data.value(), buffer, buffer_length, flags);
 }
 
-void IPv4Socket::did_receive(const IPv4Address& source_address, u16 source_port, KBuffer&& packet)
+bool IPv4Socket::did_receive(const IPv4Address& source_address, u16 source_port, KBuffer&& packet)
 {
     LOCKER(lock());
+    if (m_receive_queue.size_slow() > 2000) {
+        kprintf("IPv4Socket(%p): did_receive refusing packet since queue is full.\n", this);
+        return false;
+    }
     auto packet_size = packet.size();
     m_receive_queue.append({ source_address, source_port, move(packet) });
     m_can_read = true;
@@ -292,6 +296,7 @@ void IPv4Socket::did_receive(const IPv4Address& source_address, u16 source_port,
 #ifdef IPV4_SOCKET_DEBUG
     kprintf("IPv4Socket(%p): did_receive %d bytes, total_received=%u, packets in queue: %d\n", this, packet_size, m_bytes_received, m_receive_queue.size_slow());
 #endif
+    return true;
 }
 
 String IPv4Socket::absolute_path(const FileDescription&) const
diff --git a/Kernel/Net/IPv4Socket.h b/Kernel/Net/IPv4Socket.h
index ff59ae3831b..5c887ae2d64 100644
--- a/Kernel/Net/IPv4Socket.h
+++ b/Kernel/Net/IPv4Socket.h
@@ -27,8 +27,8 @@ public:
     virtual bool get_peer_address(sockaddr*, socklen_t*) override;
     virtual void attach(FileDescription&) override;
     virtual void detach(FileDescription&) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual ssize_t sendto(FileDescription&, const void*, size_t, int, const sockaddr*, socklen_t) override;
     virtual ssize_t recvfrom(FileDescription&, void*, size_t, int flags, sockaddr*, socklen_t*) override;
     virtual KResult setsockopt(int level, int option, const void*, socklen_t) override;
@@ -36,7 +36,7 @@ public:
 
     virtual int ioctl(FileDescription&, unsigned request, unsigned arg) override;
 
-    void did_receive(const IPv4Address& peer_address, u16 peer_port, KBuffer&&);
+    bool did_receive(const IPv4Address& peer_address, u16 peer_port, KBuffer&&);
 
     const IPv4Address& local_address() const { return m_local_address; }
     u16 local_port() const { return m_local_port; }
diff --git a/Kernel/Net/LocalSocket.cpp b/Kernel/Net/LocalSocket.cpp
index 542daada86e..6f16fed2f53 100644
--- a/Kernel/Net/LocalSocket.cpp
+++ b/Kernel/Net/LocalSocket.cpp
@@ -186,7 +186,7 @@ void LocalSocket::detach(FileDescription& description)
     }
 }
 
-bool LocalSocket::can_read(FileDescription& description) const
+bool LocalSocket::can_read(const FileDescription& description) const
 {
     auto role = this->role(description);
     if (role == Role::Listener)
@@ -208,7 +208,7 @@ bool LocalSocket::has_attached_peer(const FileDescription& description) const
     ASSERT_NOT_REACHED();
 }
 
-bool LocalSocket::can_write(FileDescription& description) const
+bool LocalSocket::can_write(const FileDescription& description) const
 {
     auto role = this->role(description);
     if (role == Role::Accepted)
diff --git a/Kernel/Net/LocalSocket.h b/Kernel/Net/LocalSocket.h
index 2a6ee5bd2be..bd529933f1b 100644
--- a/Kernel/Net/LocalSocket.h
+++ b/Kernel/Net/LocalSocket.h
@@ -25,8 +25,8 @@ public:
     virtual bool get_peer_address(sockaddr*, socklen_t*) override;
     virtual void attach(FileDescription&) override;
     virtual void detach(FileDescription&) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual ssize_t sendto(FileDescription&, const void*, size_t, int, const sockaddr*, socklen_t) override;
     virtual ssize_t recvfrom(FileDescription&, void*, size_t, int flags, sockaddr*, socklen_t*) override;
 
diff --git a/Kernel/Net/NetworkTask.cpp b/Kernel/Net/NetworkTask.cpp
index 1799c6ac98c..c6ae7bfaf7e 100644
--- a/Kernel/Net/NetworkTask.cpp
+++ b/Kernel/Net/NetworkTask.cpp
@@ -574,9 +574,12 @@ void handle_tcp(const IPv4Packet& ipv4_packet)
             socket->sequence_number());
 #endif
 
-        socket->send_tcp_packet(TCPFlags::ACK);
+        bool should_ack = true;
+        if (payload_size != 0) {
+            should_ack = socket->did_receive(ipv4_packet.source(), tcp_packet.source_port(), KBuffer::copy(&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
+        }
 
-        if (payload_size != 0)
-            socket->did_receive(ipv4_packet.source(), tcp_packet.source_port(), KBuffer::copy(&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
+        if (should_ack)
+            socket->send_tcp_packet(TCPFlags::ACK);
     }
 }
diff --git a/Kernel/ProcessTracer.h b/Kernel/ProcessTracer.h
index cfde92d2f82..5c769f6cfd5 100644
--- a/Kernel/ProcessTracer.h
+++ b/Kernel/ProcessTracer.h
@@ -12,10 +12,10 @@ public:
     bool is_dead() const { return m_dead; }
     void set_dead() { m_dead = true; }
 
-    virtual bool can_read(FileDescription&) const override { return !m_calls.is_empty() || m_dead; }
+    virtual bool can_read(const FileDescription&) const override { return !m_calls.is_empty() || m_dead; }
     virtual int read(FileDescription&, u8*, int) override;
 
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
     virtual int write(FileDescription&, const u8*, int) override { return -EIO; }
 
     virtual String absolute_path(const FileDescription&) const override;
diff --git a/Kernel/TTY/MasterPTY.cpp b/Kernel/TTY/MasterPTY.cpp
index efd29a7f27c..dc46506ce84 100644
--- a/Kernel/TTY/MasterPTY.cpp
+++ b/Kernel/TTY/MasterPTY.cpp
@@ -46,14 +46,14 @@ ssize_t MasterPTY::write(FileDescription&, const u8* buffer, ssize_t size)
     return size;
 }
 
-bool MasterPTY::can_read(FileDescription&) const
+bool MasterPTY::can_read(const FileDescription&) const
 {
     if (!m_slave)
         return true;
     return !m_buffer.is_empty();
 }
 
-bool MasterPTY::can_write(FileDescription&) const
+bool MasterPTY::can_write(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/TTY/MasterPTY.h b/Kernel/TTY/MasterPTY.h
index dbc4f46bffa..e3246dfd6aa 100644
--- a/Kernel/TTY/MasterPTY.h
+++ b/Kernel/TTY/MasterPTY.h
@@ -24,8 +24,8 @@ private:
     // ^CharacterDevice
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual void close() override;
     virtual bool is_master_pty() const override { return true; }
     virtual int ioctl(FileDescription&, unsigned request, unsigned arg) override;
diff --git a/Kernel/TTY/PTYMultiplexer.h b/Kernel/TTY/PTYMultiplexer.h
index a51520298b2..cc8ffd5b510 100644
--- a/Kernel/TTY/PTYMultiplexer.h
+++ b/Kernel/TTY/PTYMultiplexer.h
@@ -18,8 +18,8 @@ public:
     virtual KResultOr<NonnullRefPtr<FileDescription>> open(int options) override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override { return 0; }
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override { return 0; }
-    virtual bool can_read(FileDescription&) const override { return true; }
-    virtual bool can_write(FileDescription&) const override { return true; }
+    virtual bool can_read(const FileDescription&) const override { return true; }
+    virtual bool can_write(const FileDescription&) const override { return true; }
 
     void notify_master_destroyed(Badge<MasterPTY>, unsigned index);
 
diff --git a/Kernel/TTY/SlavePTY.cpp b/Kernel/TTY/SlavePTY.cpp
index 23a0378d1df..ce5461175b4 100644
--- a/Kernel/TTY/SlavePTY.cpp
+++ b/Kernel/TTY/SlavePTY.cpp
@@ -48,12 +48,12 @@ ssize_t SlavePTY::on_tty_write(const u8* data, ssize_t size)
     return m_master->on_slave_write(data, size);
 }
 
-bool SlavePTY::can_write(FileDescription&) const
+bool SlavePTY::can_write(const FileDescription&) const
 {
     return m_master->can_write_from_slave();
 }
 
-bool SlavePTY::can_read(FileDescription& description) const
+bool SlavePTY::can_read(const FileDescription& description) const
 {
     if (m_master->is_closed())
         return true;
diff --git a/Kernel/TTY/SlavePTY.h b/Kernel/TTY/SlavePTY.h
index 0659079acf2..9417b0e24df 100644
--- a/Kernel/TTY/SlavePTY.h
+++ b/Kernel/TTY/SlavePTY.h
@@ -19,9 +19,9 @@ private:
     virtual void echo(u8) override;
 
     // ^CharacterDevice
-    virtual bool can_read(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual const char* class_name() const override { return "SlavePTY"; }
     virtual void close() override;
 
diff --git a/Kernel/TTY/TTY.cpp b/Kernel/TTY/TTY.cpp
index a7777e43204..0e45e694399 100644
--- a/Kernel/TTY/TTY.cpp
+++ b/Kernel/TTY/TTY.cpp
@@ -68,7 +68,7 @@ ssize_t TTY::write(FileDescription&, const u8* buffer, ssize_t size)
     return size;
 }
 
-bool TTY::can_read(FileDescription&) const
+bool TTY::can_read(const FileDescription&) const
 {
     if (in_canonical_mode()) {
         return m_available_lines > 0;
@@ -76,7 +76,7 @@ bool TTY::can_read(FileDescription&) const
     return !m_input_buffer.is_empty();
 }
 
-bool TTY::can_write(FileDescription&) const
+bool TTY::can_write(const FileDescription&) const
 {
     return true;
 }
diff --git a/Kernel/TTY/TTY.h b/Kernel/TTY/TTY.h
index 2d4420bf34c..6e7513b9ada 100644
--- a/Kernel/TTY/TTY.h
+++ b/Kernel/TTY/TTY.h
@@ -13,8 +13,8 @@ public:
 
     virtual ssize_t read(FileDescription&, u8*, ssize_t) override;
     virtual ssize_t write(FileDescription&, const u8*, ssize_t) override;
-    virtual bool can_read(FileDescription&) const override;
-    virtual bool can_write(FileDescription&) const override;
+    virtual bool can_read(const FileDescription&) const override;
+    virtual bool can_write(const FileDescription&) const override;
     virtual int ioctl(FileDescription&, unsigned request, unsigned arg) override final;
     virtual String absolute_path(const FileDescription&) const override { return tty_name(); }