diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt
index aaec2fd6d6..ea58982611 100644
--- a/Kernel/CMakeLists.txt
+++ b/Kernel/CMakeLists.txt
@@ -110,6 +110,7 @@ set(KERNEL_SOURCES
     FileSystem/Inode.cpp
     FileSystem/InodeFile.cpp
     FileSystem/InodeWatcher.cpp
+    FileSystem/ISO9660FileSystem.cpp
     FileSystem/Mount.cpp
     FileSystem/Plan9FileSystem.cpp
     FileSystem/ProcFS.cpp
diff --git a/Kernel/Debug.h.in b/Kernel/Debug.h.in
index c9b8b6a368..aa2b30d043 100644
--- a/Kernel/Debug.h.in
+++ b/Kernel/Debug.h.in
@@ -126,6 +126,14 @@
 #cmakedefine01 IO_DEBUG
 #endif
 
+#ifndef ISO9660_DEBUG
+#cmakedefine01 ISO9660_DEBUG
+#endif
+
+#ifndef ISO9660_VERY_DEBUG
+#cmakedefine01 ISO9660_VERY_DEBUG
+#endif
+
 #ifndef IPV4_DEBUG
 #cmakedefine01 IPV4_DEBUG
 #endif
diff --git a/Kernel/FileSystem/ISO9660FileSystem.cpp b/Kernel/FileSystem/ISO9660FileSystem.cpp
new file mode 100644
index 0000000000..41e1e47600
--- /dev/null
+++ b/Kernel/FileSystem/ISO9660FileSystem.cpp
@@ -0,0 +1,735 @@
+/*
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "ISO9660FileSystem.h"
+#include "Kernel/FileSystem/BlockBasedFileSystem.h"
+#include <AK/CharacterTypes.h>
+#include <AK/Endian.h>
+#include <AK/HashFunctions.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/OwnPtr.h>
+#include <AK/RefPtr.h>
+#include <AK/StringHash.h>
+#include <AK/StringView.h>
+#include <Kernel/Debug.h>
+#include <Kernel/Forward.h>
+#include <Kernel/KBuffer.h>
+#include <Kernel/KResult.h>
+#include <Kernel/UnixTypes.h>
+#include <Kernel/UserOrKernelBuffer.h>
+
+namespace Kernel {
+
+// NOTE: According to the spec, logical blocks 0 to 15 are system use.
+constexpr u32 first_data_area_block = 16;
+constexpr u32 logical_sector_size = 2048;
+constexpr u32 max_cached_directory_entries = 128;
+
+struct DirectoryState {
+    RefPtr<ISO9660FS::DirectoryEntry> entry;
+    u32 offset { 0 };
+};
+
+class ISO9660DirectoryIterator {
+public:
+    ISO9660DirectoryIterator(ISO9660FS& fs, ISO::DirectoryRecordHeader const& header)
+        : m_fs(fs)
+        , m_current_header(&header)
+    {
+        // FIXME: Panic or alternative method?
+        (void)read_directory_contents();
+        get_header();
+    }
+
+    ISO::DirectoryRecordHeader const* operator*() { return m_current_header; }
+
+    // Recurses into subdirectories. May fail.
+    KResultOr<bool> next()
+    {
+        if (done())
+            return false;
+        dbgln_if(ISO9660_VERY_DEBUG, "next(): Called");
+
+        if (has_flag(m_current_header->file_flags, ISO::FileFlags::Directory)) {
+            dbgln_if(ISO9660_VERY_DEBUG, "next(): Recursing");
+            {
+                bool result = m_directory_stack.try_append(move(m_current_directory));
+                if (!result) {
+                    return ENOMEM;
+                }
+            }
+
+            dbgln_if(ISO9660_VERY_DEBUG, "next(): Pushed into directory stack");
+
+            {
+                auto result = read_directory_contents();
+                if (result.is_error()) {
+                    return result;
+                }
+            }
+
+            dbgln_if(ISO9660_VERY_DEBUG, "next(): Read directory contents");
+
+            m_current_directory.offset = 0;
+            get_header();
+            if (m_current_header->length == 0) {
+                // We have found an empty directory, let's continue with the
+                // next one.
+                if (!go_up())
+                    return false;
+            } else {
+                // We cannot skip here, as this is the first record in this
+                // extent.
+                return true;
+            }
+        }
+
+        return skip();
+    }
+
+    // Skips to the directory in the list, returns whether there was a next one.
+    // No allocation here, cannot fail.
+    bool skip()
+    {
+        VERIFY(m_current_directory.entry);
+
+        if (m_current_directory.offset >= m_current_directory.entry->length) {
+            dbgln_if(ISO9660_VERY_DEBUG, "skip(): Was at last item already");
+            return false;
+        }
+
+        m_current_directory.offset += m_current_header->length;
+        get_header();
+        if (m_current_header->length == 0) {
+            // According to ECMA 119, if a logical block contains directory
+            // records, then the leftover bytes in the logical block are
+            // all zeros. So if our directory header has a length of 0,
+            // we're probably looking at padding.
+            //
+            // Of course, this doesn't mean we're done; it only means that there
+            // are no more directory entries in *this* logical block.  If we
+            // have at least one more logical block of data length to go, we
+            // need to snap to the next logical block, because directory records
+            // cannot span multiple logical blocks.
+            u32 remaining_bytes = m_current_directory.entry->length - m_current_directory.offset;
+            if (remaining_bytes > m_fs.logical_block_size()) {
+                m_current_directory.offset += remaining_bytes % m_fs.logical_block_size();
+                get_header();
+
+                dbgln_if(ISO9660_VERY_DEBUG, "skip(): Snapped to next logical block (succeeded)");
+                return true;
+            }
+
+            dbgln_if(ISO9660_VERY_DEBUG, "skip(): Was at the last logical block, at padding now (offset {}, data length {})", m_current_directory.entry->length, m_current_directory.offset);
+            return false;
+        }
+
+        dbgln_if(ISO9660_VERY_DEBUG, "skip(): Skipped to next item");
+        return true;
+    }
+
+    bool go_up()
+    {
+        if (m_directory_stack.is_empty()) {
+            dbgln_if(ISO9660_VERY_DEBUG, "go_up(): Empty directory stack");
+            return false;
+        }
+
+        m_current_directory = m_directory_stack.take_last();
+        get_header();
+
+        dbgln_if(ISO9660_VERY_DEBUG, "go_up(): Went up a directory");
+        return true;
+    }
+
+    bool done() const
+    {
+        VERIFY(m_current_directory.entry);
+        auto result = m_directory_stack.is_empty() && m_current_directory.offset >= m_current_directory.entry->length;
+        dbgln_if(ISO9660_VERY_DEBUG, "done(): {}", result);
+        return result;
+    }
+
+private:
+    KResult read_directory_contents()
+    {
+        auto result = m_fs.directory_entry_for_record({}, m_current_header);
+        if (result.is_error()) {
+            return result.error();
+        }
+
+        m_current_directory.entry = result.value();
+        return KSuccess;
+    }
+
+    void get_header()
+    {
+        VERIFY(m_current_directory.entry);
+        if (!m_current_directory.entry->blocks)
+            return;
+
+        m_current_header = reinterpret_cast<ISO::DirectoryRecordHeader const*>(m_current_directory.entry->blocks->data() + m_current_directory.offset);
+    }
+
+    ISO9660FS& m_fs;
+
+    DirectoryState m_current_directory;
+    ISO::DirectoryRecordHeader const* m_current_header { nullptr };
+
+    Vector<DirectoryState> m_directory_stack;
+};
+
+KResultOr<NonnullRefPtr<ISO9660FS>> ISO9660FS::try_create(FileDescription& description)
+{
+    auto result = adopt_ref_if_nonnull(new (nothrow) ISO9660FS(description));
+    if (!result) {
+        return ENOMEM;
+    }
+    return result.release_nonnull();
+}
+
+ISO9660FS::ISO9660FS(FileDescription& description)
+    : BlockBasedFileSystem(description)
+{
+    set_block_size(logical_sector_size);
+    m_logical_block_size = logical_sector_size;
+}
+
+ISO9660FS::~ISO9660FS()
+{
+}
+
+bool ISO9660FS::initialize()
+{
+    if (!BlockBasedFileSystem::initialize())
+        return false;
+
+    // FIXME: Fix the FileSystem::initialize contract to be able to return a
+    //        KResult.
+    if (parse_volume_set().is_error())
+        return false;
+    if (create_root_inode().is_error())
+        return false;
+    return true;
+}
+
+Inode& ISO9660FS::root_inode()
+{
+    VERIFY(!m_root_inode.is_null());
+    return *m_root_inode;
+}
+
+unsigned ISO9660FS::total_block_count() const
+{
+    return LittleEndian { m_primary_volume->volume_space_size.little };
+}
+
+unsigned ISO9660FS::total_inode_count() const
+{
+    if (!m_cached_inode_count) {
+        auto result = calculate_inode_count();
+        if (result.is_error()) {
+            // FIXME: This should be able to return a KResult.
+            return 0;
+        }
+    }
+
+    return m_cached_inode_count;
+}
+
+u8 ISO9660FS::internal_file_type_to_directory_entry_type(const DirectoryEntryView& entry) const
+{
+    if (has_flag(static_cast<ISO::FileFlags>(entry.file_type), ISO::FileFlags::Directory)) {
+        return DT_DIR;
+    }
+
+    return DT_REG;
+}
+
+KResult ISO9660FS::parse_volume_set()
+{
+    VERIFY(!m_primary_volume);
+
+    auto block = KBuffer::try_create_with_size(m_logical_block_size, Memory::Region::Access::Read | Memory::Region::Access::Write, "ISO9660FS: Temporary volume descriptor storage");
+    if (!block) {
+        return ENOMEM;
+    }
+
+    auto block_buffer = UserOrKernelBuffer::for_kernel_buffer(block->data());
+
+    auto current_block_index = first_data_area_block;
+    while (true) {
+        bool result = raw_read(BlockIndex { current_block_index }, block_buffer);
+        if (!result) {
+            dbgln_if(ISO9660_DEBUG, "Failed to read volume descriptor from ISO file");
+            return EIO;
+        }
+
+        auto header = reinterpret_cast<ISO::VolumeDescriptorHeader const*>(block->data());
+        if (StringView { header->identifier, 5 } != "CD001") {
+            dbgln_if(ISO9660_DEBUG, "Header magic at volume descriptor {} is not valid", current_block_index - first_data_area_block);
+            return EIO;
+        }
+
+        switch (header->type) {
+        case ISO::VolumeDescriptorType::PrimaryVolumeDescriptor: {
+            auto primary_volume = reinterpret_cast<ISO::PrimaryVolumeDescriptor const*>(header);
+            m_primary_volume = adopt_own_if_nonnull(new ISO::PrimaryVolumeDescriptor(*primary_volume));
+            break;
+        }
+        case ISO::VolumeDescriptorType::BootRecord:
+        case ISO::VolumeDescriptorType::SupplementaryOrEnhancedVolumeDescriptor:
+        case ISO::VolumeDescriptorType::VolumePartitionDescriptor: {
+            break;
+        }
+        case ISO::VolumeDescriptorType::VolumeDescriptorSetTerminator: {
+            goto all_headers_read;
+        }
+        default:
+            dbgln_if(ISO9660_DEBUG, "Unexpected volume descriptor type {} in volume set", static_cast<u8>(header->type));
+            return EIO;
+        }
+
+        current_block_index++;
+    }
+
+all_headers_read:
+    if (!m_primary_volume) {
+        dbgln_if(ISO9660_DEBUG, "Could not find primary volume");
+        return EIO;
+    }
+
+    m_logical_block_size = LittleEndian { m_primary_volume->logical_block_size.little };
+    return KSuccess;
+}
+
+KResult ISO9660FS::create_root_inode()
+{
+    if (!m_primary_volume) {
+        dbgln_if(ISO9660_DEBUG, "Primary volume doesn't exist, can't create root inode");
+        return EIO;
+    }
+
+    auto maybe_inode = ISO9660Inode::try_create_from_directory_record(*this, m_primary_volume->root_directory_record_header, {});
+    if (maybe_inode.is_error()) {
+        return ENOMEM;
+    }
+
+    m_root_inode = maybe_inode.release_value();
+    return KSuccess;
+}
+
+KResult ISO9660FS::calculate_inode_count() const
+{
+    if (!m_primary_volume) {
+        dbgln_if(ISO9660_DEBUG, "Primary volume doesn't exist, can't calculate inode count");
+        return EIO;
+    }
+
+    size_t inode_count = 1;
+
+    auto traversal_result = visit_directory_record(m_primary_volume->root_directory_record_header, [&](ISO::DirectoryRecordHeader const* header) {
+        if (header == nullptr) {
+            return RecursionDecision::Continue;
+        }
+
+        inode_count += 1;
+
+        if (has_flag(header->file_flags, ISO::FileFlags::Directory)) {
+            if (header->file_identifier_length == 1) {
+                auto file_identifier = reinterpret_cast<u8 const*>(header + 1);
+                if (file_identifier[0] == '\0' || file_identifier[0] == '\1') {
+                    return RecursionDecision::Continue;
+                }
+            }
+
+            return RecursionDecision::Recurse;
+        }
+
+        return RecursionDecision::Continue;
+    });
+
+    if (traversal_result.is_error()) {
+        dbgln_if(ISO9660_DEBUG, "Failed to traverse for caching inode count!");
+        return traversal_result;
+    }
+
+    m_cached_inode_count = inode_count;
+    return KSuccess;
+}
+
+KResult ISO9660FS::visit_directory_record(ISO::DirectoryRecordHeader const& record, Function<KResultOr<RecursionDecision>(ISO::DirectoryRecordHeader const*)> const& visitor) const
+{
+    if (!has_flag(record.file_flags, ISO::FileFlags::Directory)) {
+        return KSuccess;
+    }
+
+    ISO9660DirectoryIterator iterator { const_cast<ISO9660FS&>(*this), record };
+
+    while (!iterator.done()) {
+        auto maybe_result = visitor(*iterator);
+        if (maybe_result.is_error()) {
+            return maybe_result.error();
+        }
+
+        switch (maybe_result.value()) {
+        case RecursionDecision::Recurse: {
+            auto maybe_has_moved = iterator.next();
+            if (maybe_has_moved.is_error()) {
+                return maybe_has_moved.error();
+            }
+
+            if (!maybe_has_moved.value()) {
+                // If next() hasn't moved then we have read through all the
+                // directories, and can exit.
+                return KSuccess;
+            }
+
+            continue;
+        }
+        case RecursionDecision::Continue: {
+            while (!iterator.done()) {
+                if (iterator.skip())
+                    break;
+                if (!iterator.go_up())
+                    return KSuccess;
+            }
+
+            continue;
+        }
+        case RecursionDecision::Break:
+            return KSuccess;
+        }
+    }
+
+    return KSuccess;
+}
+
+KResultOr<NonnullRefPtr<ISO9660FS::DirectoryEntry>> ISO9660FS::directory_entry_for_record(Badge<ISO9660DirectoryIterator>, ISO::DirectoryRecordHeader const* record)
+{
+    u32 extent_location = LittleEndian { record->extent_location.little };
+    u32 data_length = LittleEndian { record->data_length.little };
+
+    auto key = calculate_directory_entry_cache_key(*record);
+    auto it = m_directory_entry_cache.find(key);
+    if (it != m_directory_entry_cache.end()) {
+        dbgln_if(ISO9660_DEBUG, "Cache hit for dirent @ {}", extent_location);
+        return it->value;
+    }
+    dbgln_if(ISO9660_DEBUG, "Cache miss for dirent @ {} :^(", extent_location);
+
+    if (m_directory_entry_cache.size() == max_cached_directory_entries) {
+        // FIXME: A smarter algorithm would probably be nicer.
+        m_directory_entry_cache.remove(m_directory_entry_cache.begin());
+    }
+
+    if (!(data_length % logical_block_size() == 0)) {
+        dbgln_if(ISO9660_DEBUG, "Found a directory with non-logical block size aligned data length!");
+        return EIO;
+    }
+
+    auto blocks = KBuffer::try_create_with_size(data_length, Memory::Region::Access::Read | Memory::Region::Access::Write, "ISO9660FS: Directory traversal buffer");
+    if (!blocks) {
+        return ENOMEM;
+    }
+
+    auto blocks_buffer = UserOrKernelBuffer::for_kernel_buffer(blocks->data());
+    auto did_read = raw_read_blocks(BlockBasedFileSystem::BlockIndex { extent_location }, data_length / logical_block_size(), blocks_buffer);
+    if (!did_read) {
+        return EIO;
+    }
+
+    auto maybe_entry = DirectoryEntry::try_create(extent_location, data_length, move(blocks));
+    if (maybe_entry.is_error()) {
+        return maybe_entry.error();
+    }
+    m_directory_entry_cache.set(key, maybe_entry.value());
+
+    dbgln_if(ISO9660_DEBUG, "Cached dirent @ {}", extent_location);
+    return maybe_entry.release_value();
+}
+
+u32 ISO9660FS::calculate_directory_entry_cache_key(ISO::DirectoryRecordHeader const& record)
+{
+    return LittleEndian { record.extent_location.little };
+}
+
+KResultOr<size_t> ISO9660Inode::read_bytes(off_t offset, size_t size, UserOrKernelBuffer& buffer, FileDescription*) const
+{
+    MutexLocker inode_locker(m_inode_lock);
+
+    auto& file_system = const_cast<ISO9660FS&>(static_cast<ISO9660FS const&>(fs()));
+    u32 data_length = LittleEndian { m_record.data_length.little };
+    u32 extent_location = LittleEndian { m_record.extent_location.little };
+
+    if (static_cast<u64>(offset) >= data_length)
+        return 0;
+
+    auto block = KBuffer::try_create_with_size(file_system.m_logical_block_size);
+    if (!block) {
+        return ENOMEM;
+    }
+    auto block_buffer = UserOrKernelBuffer::for_kernel_buffer(block->data());
+
+    size_t total_bytes = min(size, data_length - offset);
+    size_t nread = 0;
+    size_t blocks_already_read = offset / file_system.m_logical_block_size;
+    size_t initial_offset = offset % file_system.m_logical_block_size;
+
+    auto current_block_index = BlockBasedFileSystem::BlockIndex { extent_location + blocks_already_read };
+    while (nread != total_bytes) {
+        size_t bytes_to_read = min(total_bytes - nread, file_system.logical_block_size() - initial_offset);
+        auto buffer_offset = buffer.offset(nread);
+        dbgln_if(ISO9660_VERY_DEBUG, "ISO9660Inode::read_bytes: Reading {} bytes into buffer offset {}/{}, logical block index: {}", bytes_to_read, nread, total_bytes, current_block_index.value());
+
+        if (bool result = file_system.raw_read(current_block_index, block_buffer); !result) {
+            return EIO;
+        }
+
+        bool result = buffer_offset.write(block->data() + initial_offset, bytes_to_read);
+        if (!result) {
+            return EFAULT;
+        }
+
+        nread += bytes_to_read;
+        initial_offset = 0;
+        current_block_index = BlockBasedFileSystem::BlockIndex { current_block_index.value() + 1 };
+    }
+
+    return nread;
+}
+
+InodeMetadata ISO9660Inode::metadata() const
+{
+    return m_metadata;
+}
+
+KResult ISO9660Inode::traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)> visitor) const
+{
+    auto& file_system = static_cast<ISO9660FS const&>(fs());
+    Array<u8, max_file_identifier_length> file_identifier_buffer;
+
+    auto traversal_result = file_system.visit_directory_record(m_record, [&](ISO::DirectoryRecordHeader const* record) {
+        StringView filename = get_normalized_filename(*record, file_identifier_buffer);
+        dbgln_if(ISO9660_VERY_DEBUG, "traverse_as_directory(): Found {}", filename);
+
+        InodeIdentifier id { fsid(), get_inode_index(*record, filename) };
+        auto entry = FileSystem::DirectoryEntryView(filename, id, static_cast<u8>(record->file_flags));
+
+        if (!visitor(entry)) {
+            return RecursionDecision::Break;
+        }
+
+        return RecursionDecision::Continue;
+    });
+
+    if (traversal_result.is_error())
+        return traversal_result;
+
+    return KSuccess;
+}
+
+RefPtr<Inode> ISO9660Inode::lookup(StringView name)
+{
+    auto& file_system = static_cast<ISO9660FS const&>(fs());
+    RefPtr<Inode> inode;
+    Array<u8, max_file_identifier_length> file_identifier_buffer;
+
+    auto traversal_result = file_system.visit_directory_record(m_record, [&](ISO::DirectoryRecordHeader const* record) {
+        StringView filename = get_normalized_filename(*record, file_identifier_buffer);
+
+        if (filename == name) {
+            auto maybe_inode = ISO9660Inode::try_create_from_directory_record(const_cast<ISO9660FS&>(file_system), *record, filename);
+            if (maybe_inode.is_error()) {
+                // FIXME: The Inode API does not handle allocation failures very
+                //        well... we can't return a KResultOr from here. It
+                //        would be nice if we could return a KResult(Or) from
+                //        any place where allocation may happen.
+                dbgln("Could not allocate inode for lookup!");
+            } else {
+                inode = maybe_inode.release_value();
+            }
+            return RecursionDecision::Break;
+        }
+
+        return RecursionDecision::Continue;
+    });
+
+    if (traversal_result.is_error()) {
+        return {};
+    }
+
+    return inode;
+}
+
+void ISO9660Inode::flush_metadata()
+{
+}
+
+KResultOr<size_t> ISO9660Inode::write_bytes(off_t, size_t, const UserOrKernelBuffer&, FileDescription*)
+{
+    return EROFS;
+}
+
+KResultOr<NonnullRefPtr<Inode>> ISO9660Inode::create_child(StringView, mode_t, dev_t, uid_t, gid_t)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::add_child(Inode&, const StringView&, mode_t)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::remove_child(const StringView&)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::chmod(mode_t)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::chown(uid_t, gid_t)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::truncate(u64)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::set_atime(time_t)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::set_ctime(time_t)
+{
+    return EROFS;
+}
+
+KResult ISO9660Inode::set_mtime(time_t)
+{
+    return EROFS;
+}
+
+void ISO9660Inode::one_ref_left()
+{
+}
+
+ISO9660Inode::ISO9660Inode(ISO9660FS& fs, ISO::DirectoryRecordHeader const& record, StringView const& name)
+    : Inode(fs, get_inode_index(record, name))
+    , m_record(record)
+{
+    dbgln_if(ISO9660_VERY_DEBUG, "Creating inode #{}", index());
+    create_metadata();
+}
+
+ISO9660Inode::~ISO9660Inode()
+{
+}
+
+KResultOr<NonnullRefPtr<ISO9660Inode>> ISO9660Inode::try_create_from_directory_record(ISO9660FS& fs, ISO::DirectoryRecordHeader const& record, StringView const& name)
+{
+    auto result = adopt_ref_if_nonnull(new (nothrow) ISO9660Inode(fs, record, name));
+    if (!result) {
+        return ENOMEM;
+    }
+    return result.release_nonnull();
+}
+
+void ISO9660Inode::create_metadata()
+{
+    u32 data_length = LittleEndian { m_record.data_length.little };
+    bool is_directory = has_flag(m_record.file_flags, ISO::FileFlags::Directory);
+    time_t recorded_at = parse_numerical_date_time(m_record.recording_date_and_time);
+
+    m_metadata = {
+        .inode = identifier(),
+        .size = data_length,
+        .mode = static_cast<mode_t>((is_directory ? S_IFDIR : S_IFREG) | (is_directory ? 0555 : 0444)),
+        .uid = 0,
+        .gid = 0,
+        .link_count = 1,
+        .atime = recorded_at,
+        .ctime = recorded_at,
+        .mtime = recorded_at,
+        .dtime = 0,
+        .block_count = 0,
+        .block_size = 0,
+        .major_device = 0,
+        .minor_device = 0,
+    };
+}
+
+time_t ISO9660Inode::parse_numerical_date_time(ISO::NumericalDateAndTime const& date)
+{
+    i32 year_offset = date.years_since_1900 - 70;
+
+    return (year_offset * 60 * 60 * 24 * 30 * 12)
+        + (date.month * 60 * 60 * 24 * 30)
+        + (date.day * 60 * 60 * 24)
+        + (date.hour * 60 * 60)
+        + (date.minute * 60)
+        + date.second;
+}
+
+StringView ISO9660Inode::get_normalized_filename(ISO::DirectoryRecordHeader const& record, Bytes buffer)
+{
+    auto file_identifier = reinterpret_cast<u8 const*>(&record + 1);
+    auto filename = StringView { file_identifier, record.file_identifier_length };
+
+    if (filename.length() == 1) {
+        if (filename[0] == '\0') {
+            filename = "."sv;
+        }
+
+        if (filename[0] == '\1') {
+            filename = ".."sv;
+        }
+    }
+
+    if (!has_flag(record.file_flags, ISO::FileFlags::Directory)) {
+        // FIXME: We currently strip the file version from the filename,
+        //        but that may be used later down the line if the file actually
+        //        has multiple versions on the disk.
+        Optional<size_t> semicolon = filename.find(';');
+        if (semicolon.has_value()) {
+            filename = filename.substring_view(0, semicolon.value());
+        }
+
+        if (filename[filename.length() - 1] == '.') {
+            filename = filename.substring_view(0, filename.length() - 1);
+        }
+    }
+
+    if (filename.length() > buffer.size()) {
+        // FIXME: Rock Ridge allows filenames up to 255 characters, so we should
+        //        probably support that instead of truncating.
+        filename = filename.substring_view(0, buffer.size());
+    }
+
+    for (size_t i = 0; i < filename.length(); i++) {
+        buffer[i] = to_ascii_lowercase(filename[i]);
+    }
+
+    return { buffer.data(), filename.length() };
+}
+
+InodeIndex ISO9660Inode::get_inode_index(ISO::DirectoryRecordHeader const& record, StringView const& name)
+{
+    if (name.is_null()) {
+        // NOTE: This is the index of the root inode.
+        return 1;
+    }
+
+    return { pair_int_hash(LittleEndian { record.extent_location.little }, string_hash(name.characters_without_null_termination(), name.length())) };
+}
+
+}
diff --git a/Kernel/FileSystem/ISO9660FileSystem.h b/Kernel/FileSystem/ISO9660FileSystem.h
new file mode 100644
index 0000000000..65a160cd44
--- /dev/null
+++ b/Kernel/FileSystem/ISO9660FileSystem.h
@@ -0,0 +1,390 @@
+/*
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/EnumBits.h>
+#include <AK/HashMap.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/RecursionDecision.h>
+#include <AK/StringView.h>
+#include <AK/Types.h>
+#include <Kernel/FileSystem/BlockBasedFileSystem.h>
+#include <Kernel/FileSystem/Inode.h>
+#include <Kernel/KBuffer.h>
+#include <Kernel/KResult.h>
+
+namespace Kernel {
+
+namespace ISO {
+
+// The implemented spec here is ECMA 119, available at:
+// https://www.ecma-international.org/wp-content/uploads/ECMA-119_4th_edition_june_2019.pdf
+
+template<typename T>
+struct [[gnu::packed]] LittleAndBigEndian {
+    T little;
+    T big;
+};
+
+// 8.4.26.1 Date and Time Format
+struct [[gnu::packed]] AsciiDateAndTime {
+    // All of these fields are ASCII digits. :^)
+    u8 year[4];
+    u8 month[2];
+    u8 day[2];
+
+    u8 hour[2];
+    u8 minute[2];
+    u8 second[2];
+    u8 hundredths_of_second[2];
+
+    // From OSDev wiki:
+    // Time zone offset from GMT in 15 minute intervals, starting at
+    // interval -48 (west) and running up to interval 52 (east). So value 0
+    // indicates interval -48 which equals GMT-12 hours, and value 100
+    // indicates interval 52 which equals GMT+13 hours.
+    u8 timezone_offset;
+};
+static_assert(sizeof(AsciiDateAndTime) == 17);
+
+// 9.1.5 Recording Date and Time (BP 19 to 25)
+struct [[gnu::packed]] NumericalDateAndTime {
+    u8 years_since_1900;
+    u8 month;
+    u8 day;
+    u8 hour;
+    u8 minute;
+    u8 second;
+    // Same format as AsciiDateAndTime.
+    u8 timezone_offset;
+};
+static_assert(sizeof(NumericalDateAndTime) == 7);
+
+// --- Path Table ---
+
+// 9.4 Format of a Path Table Record
+struct [[gnu::packed]] PathTableRecord {
+    u8 directory_identifier_length;
+    u8 extended_attribute_record_length;
+    u32 extent_location;
+    u16 parent_directory_number;
+
+    u8 directory_identifier[];
+};
+static_assert(sizeof(PathTableRecord) == 8);
+
+// --- Extended Attribute Record ---
+
+// 9.5.3 Permissions
+enum class ExtendedPermissions : u16 {
+    SystemGroupReadable = 1 << 0,
+    SystemGroupExecutable = 1 << 2,
+    UserReadable = 1 << 4,
+    UserExecutable = 1 << 6,
+    GroupReadable = 1 << 8,
+    GroupExecutable = 1 << 10,
+    OtherReadable = 1 << 12,
+    OtherExecutable = 1 << 14,
+};
+AK_ENUM_BITWISE_OPERATORS(ExtendedPermissions);
+
+// 9.5.8 Record Format
+enum class RecordFormat : u8 {
+    NotSpecified = 0,
+    FixedLengthRecords = 1,
+    LittleEndianVariableRecords = 2,
+    BigEndianVariableRecords = 3,
+    // 4-127 are reserved for future standardization.
+    // 128-255 are reserved for system use.
+};
+
+// 9.5.9 Record Attributes
+enum class RecordAttributes : u8 {
+    // This value means the record is stored like: \n123456\r.
+    LfCrDelimited = 0,
+    FortranVerticalSpacing = 1,
+    ContainsControlInformation = 2,
+    // 3-255 are reserved for future standardization.
+};
+
+// 9.5 Format of an Extended Attribute Record
+struct [[gnu::packed]] ExtendedAttributeRecord {
+    LittleAndBigEndian<u16> owner_identification;
+    LittleAndBigEndian<u16> group_identification;
+    ExtendedPermissions permissions;
+
+    AsciiDateAndTime file_creation_date_and_time;
+    AsciiDateAndTime file_modification_date_and_time;
+    AsciiDateAndTime file_expiration_date_and_time;
+    AsciiDateAndTime file_effective_date_and_time;
+
+    RecordFormat record_format;
+    u8 record_attributes;
+
+    LittleAndBigEndian<u16> record_length;
+
+    u8 system_identifier[32];
+    u8 system_use[64];
+
+    u8 extended_attribute_record_version;
+    u8 escape_sequence_length;
+
+    u8 reserved[64];
+
+    LittleAndBigEndian<u16> application_use_length;
+
+    // NOTE: Application use is immediately followed by escape sequences (no
+    // padding).
+    u8 application_use_and_escape_sequences[];
+};
+static_assert(sizeof(ExtendedAttributeRecord) == 250);
+
+// --- Files and Directories ---
+
+// 9.1.6 File Flags
+enum class FileFlags : u8 {
+    Hidden = 1 << 0, // The "existence" flag
+    Directory = 1 << 1,
+    AssociatedFile = 1 << 2,
+    Record = 1 << 3,
+    Protection = 1 << 4,
+    // 5 and 6 are reserved.
+    MultiExtent = 1 << 7,
+};
+
+AK_ENUM_BITWISE_OPERATORS(FileFlags);
+
+struct [[gnu::packed]] DirectoryRecordHeader {
+    u8 length;
+    u8 extended_attribute_record_length;
+    LittleAndBigEndian<u32> extent_location;
+    LittleAndBigEndian<u32> data_length;
+    NumericalDateAndTime recording_date_and_time;
+    FileFlags file_flags;
+    u8 file_unit_size;
+    u8 interleave_gap_size;
+    LittleAndBigEndian<u16> volume_sequence_number;
+    u8 file_identifier_length;
+
+    // NOTE: The file identifier itself is of variable length, so it and the
+    // fields following it are not included in this struct. Instead, they are:
+    //
+    // 34 to (33+file_identifier_length) - file identifier
+    // 1 byte of padding, if file_identifier_length is even
+    //
+    // The remaining bytes are system use (ISO9660 extensions).
+};
+static_assert(sizeof(DirectoryRecordHeader) == 33);
+
+// --- Volume Descriptors ---
+
+enum class VolumeDescriptorType : u8 {
+    BootRecord = 0,
+    PrimaryVolumeDescriptor = 1,
+    SupplementaryOrEnhancedVolumeDescriptor = 2,
+    VolumePartitionDescriptor = 3,
+    // 4-254 are reserved.
+    VolumeDescriptorSetTerminator = 255,
+};
+
+// 8.1 Format of a Volume Descriptor
+struct [[gnu::packed]] VolumeDescriptorHeader {
+    VolumeDescriptorType type;
+    // NOTE: Contains exactly "CD001".
+    u8 identifier[5];
+    u8 version;
+};
+static_assert(sizeof(VolumeDescriptorHeader) == 7);
+
+// 8.2 Boot Record
+struct [[gnu::packed]] BootRecord {
+    VolumeDescriptorHeader header;
+    u8 boot_system_identifier[32];
+    u8 boot_identifier[32];
+    u8 boot_system_use[1977];
+};
+static_assert(sizeof(BootRecord) == 2048);
+
+// 8.3 Volume Descriptor Set Terminator
+struct [[gnu::packed]] VolumeDescriptorSetTerminator {
+    VolumeDescriptorHeader header;
+    u8 zeros[2041];
+};
+static_assert(sizeof(VolumeDescriptorSetTerminator) == 2048);
+
+// 8.4 Primary Volume Descriptor
+struct [[gnu::packed]] PrimaryVolumeDescriptor {
+    VolumeDescriptorHeader header;
+    u8 unused1;
+    u8 system_identifier[32];
+    u8 volume_identifier[32];
+    u64 unused2;
+    LittleAndBigEndian<u32> volume_space_size;
+    u8 unused3[32];
+    LittleAndBigEndian<u16> volume_set_size;
+    LittleAndBigEndian<u16> volume_sequence_number;
+    LittleAndBigEndian<u16> logical_block_size;
+    LittleAndBigEndian<u32> path_table_size;
+
+    u32 l_path_table_occurrence_location;
+    u32 l_path_table_optional_occurrence_location;
+    u32 m_path_table_occurrence_location;
+    u32 m_path_table_optional_occurrence_location;
+
+    DirectoryRecordHeader root_directory_record_header;
+    u8 root_directory_identifier; // Exactly 0x00.
+
+    u8 volume_set_identifier[128];
+    u8 publisher_identifier[128];
+    u8 data_preparer_identifier[128];
+    u8 application_identifier[128];
+
+    u8 copyright_file_identifier[37];
+    u8 abstract_file_identifier[37];
+    u8 bibliographic_file_identifier[37];
+
+    AsciiDateAndTime volume_creation_date_and_time;
+    AsciiDateAndTime volume_modification_date_and_time;
+    AsciiDateAndTime volume_expiration_date_and_time;
+    AsciiDateAndTime volume_effective_date_and_time;
+
+    u8 file_structure_version; // Always 0x01.
+    u8 unused4;
+    u8 application_use[512];
+    u8 reserved[653];
+};
+static_assert(sizeof(PrimaryVolumeDescriptor) == 2048);
+
+// 8.6 Volume Partition Descriptor
+struct [[gnu::packed]] VolumePartitionDescriptor {
+    VolumeDescriptorHeader header;
+    u8 unused;
+
+    u8 system_identifier[32];
+    u8 volume_partition_identifier[32];
+    LittleAndBigEndian<u32> volume_partition_location;
+    LittleAndBigEndian<u32> volume_partition_size;
+
+    u8 system_use[1960];
+};
+static_assert(sizeof(VolumePartitionDescriptor) == 2048);
+
+}
+
+class ISO9660Inode;
+class ISO9660DirectoryIterator;
+
+class ISO9660FS final : public BlockBasedFileSystem {
+    friend ISO9660Inode;
+    friend ISO9660DirectoryIterator;
+
+public:
+    struct DirectoryEntry : public RefCounted<DirectoryEntry> {
+        u32 extent { 0 };
+        u32 length { 0 };
+
+        // NOTE: This can never be empty if we read the directory successfully.
+        //       We need it as an OwnPtr to default-construct this struct.
+        OwnPtr<KBuffer> blocks;
+
+        static KResultOr<NonnullRefPtr<DirectoryEntry>> try_create(u32 extent, u32 length, OwnPtr<KBuffer> blocks)
+        {
+            auto result = adopt_ref_if_nonnull(new (nothrow) DirectoryEntry(extent, length, move(blocks)));
+            if (!result) {
+                return ENOMEM;
+            }
+            return result.release_nonnull();
+        }
+
+    private:
+        DirectoryEntry(u32 extent, u32 length, OwnPtr<KBuffer> blocks)
+            : extent(extent)
+            , length(length)
+            , blocks(move(blocks))
+        {
+        }
+    };
+
+    static KResultOr<NonnullRefPtr<ISO9660FS>> try_create(FileDescription&);
+
+    virtual ~ISO9660FS() override;
+    virtual bool initialize() override;
+    virtual StringView class_name() const override { return "ISO9660FS"; }
+    virtual Inode& root_inode() override;
+
+    virtual unsigned total_block_count() const override;
+    virtual unsigned total_inode_count() const override;
+
+    virtual u8 internal_file_type_to_directory_entry_type(DirectoryEntryView const& entry) const override;
+
+    KResultOr<NonnullRefPtr<DirectoryEntry>> directory_entry_for_record(Badge<ISO9660DirectoryIterator>, ISO::DirectoryRecordHeader const* record);
+
+private:
+    ISO9660FS(FileDescription&);
+
+    KResult parse_volume_set();
+    KResult create_root_inode();
+    KResult calculate_inode_count() const;
+
+    u32 calculate_directory_entry_cache_key(ISO::DirectoryRecordHeader const&);
+
+    KResult visit_directory_record(ISO::DirectoryRecordHeader const& record, Function<KResultOr<RecursionDecision>(ISO::DirectoryRecordHeader const*)> const& visitor) const;
+
+    OwnPtr<ISO::PrimaryVolumeDescriptor> m_primary_volume;
+    RefPtr<ISO9660Inode> m_root_inode;
+
+    mutable u32 m_cached_inode_count { 0 };
+    HashMap<u32, NonnullRefPtr<DirectoryEntry>> m_directory_entry_cache;
+};
+
+class ISO9660Inode final : public Inode {
+    friend ISO9660FS;
+
+public:
+    virtual ~ISO9660Inode() override;
+
+    // ^Inode
+    virtual KResultOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, FileDescription*) const override;
+    virtual InodeMetadata metadata() const override;
+    virtual KResult traverse_as_directory(Function<bool(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual RefPtr<Inode> lookup(StringView name) override;
+    virtual void flush_metadata() override;
+    virtual KResultOr<size_t> write_bytes(off_t, size_t, const UserOrKernelBuffer& buffer, FileDescription*) override;
+    virtual KResultOr<NonnullRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, uid_t, gid_t) override;
+    virtual KResult add_child(Inode&, const StringView& name, mode_t) override;
+    virtual KResult remove_child(const StringView& name) override;
+    virtual KResult chmod(mode_t) override;
+    virtual KResult chown(uid_t, gid_t) override;
+    virtual KResult truncate(u64) override;
+    virtual KResult set_atime(time_t) override;
+    virtual KResult set_ctime(time_t) override;
+    virtual KResult set_mtime(time_t) override;
+    virtual void one_ref_left() override;
+
+private:
+    // HACK: The base ISO 9660 standard says the maximum filename length is 37
+    // bytes large; however, we can read filenames longer than that right now
+    // without any problems, so let's allow it anyway.
+    static constexpr size_t max_file_identifier_length = 256 - sizeof(ISO::DirectoryRecordHeader);
+
+    ISO9660Inode(ISO9660FS&, ISO::DirectoryRecordHeader const& record, StringView const& name);
+    static KResultOr<NonnullRefPtr<ISO9660Inode>> try_create_from_directory_record(ISO9660FS&, ISO::DirectoryRecordHeader const& record, StringView const& name);
+
+    static InodeIndex get_inode_index(ISO::DirectoryRecordHeader const& record, StringView const& name);
+    static StringView get_normalized_filename(ISO::DirectoryRecordHeader const& record, Bytes buffer);
+
+    void create_metadata();
+    time_t parse_numerical_date_time(ISO::NumericalDateAndTime const&);
+
+    InodeMetadata m_metadata;
+    ISO::DirectoryRecordHeader m_record;
+};
+
+}
+
+using Kernel::ISO::has_any_flag;
+using Kernel::ISO::has_flag;
diff --git a/Kernel/Syscalls/mount.cpp b/Kernel/Syscalls/mount.cpp
index 5bfcb5fec3..2591aa9976 100644
--- a/Kernel/Syscalls/mount.cpp
+++ b/Kernel/Syscalls/mount.cpp
@@ -8,6 +8,7 @@
 #include <Kernel/FileSystem/DevFS.h>
 #include <Kernel/FileSystem/DevPtsFS.h>
 #include <Kernel/FileSystem/Ext2FileSystem.h>
+#include <Kernel/FileSystem/ISO9660FileSystem.h>
 #include <Kernel/FileSystem/Plan9FileSystem.h>
 #include <Kernel/FileSystem/ProcFS.h>
 #include <Kernel/FileSystem/SysFS.h>
@@ -98,6 +99,21 @@ KResultOr<FlatPtr> Process::sys$mount(Userspace<const Syscall::SC_mount_params*>
         fs = SysFS::create();
     } else if (fs_type == "tmp"sv || fs_type == "TmpFS"sv) {
         fs = TmpFS::create();
+    } else if (fs_type == "iso9660"sv || fs_type == "ISO9660FS"sv) {
+        if (description.is_null())
+            return EBADF;
+        if (!description->file().is_seekable()) {
+            dbgln("mount: this is not a seekable file");
+            return ENODEV;
+        }
+
+        dbgln("mount: attempting to mount {} on {}", description->absolute_path(), target);
+
+        auto maybe_fs = ISO9660FS::try_create(*description);
+        if (maybe_fs.is_error()) {
+            return maybe_fs.error();
+        }
+        fs = maybe_fs.release_value();
     } else {
         return ENODEV;
     }
diff --git a/Meta/CMake/all_the_debug_macros.cmake b/Meta/CMake/all_the_debug_macros.cmake
index bf5c102a80..0bb7a3694b 100644
--- a/Meta/CMake/all_the_debug_macros.cmake
+++ b/Meta/CMake/all_the_debug_macros.cmake
@@ -88,6 +88,8 @@ set(IPV4_DEBUG ON)
 set(IPV4_SOCKET_DEBUG ON)
 set(IRC_DEBUG ON)
 set(IRQ_DEBUG ON)
+set(ISO9660_DEBUG ON)
+set(ISO9660_VERY_DEBUG ON)
 set(ITEM_RECTS_DEBUG ON)
 set(JOB_DEBUG ON)
 set(JPG_DEBUG ON)