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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/DevPtsFS/FileSystem.h>
#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
#include <Kernel/FileSystem/FATFS/FileSystem.h>
#include <Kernel/FileSystem/ISO9660FS/FileSystem.h>
#include <Kernel/FileSystem/Plan9FS/FileSystem.h>
#include <Kernel/FileSystem/ProcFS/FileSystem.h>
#include <Kernel/FileSystem/RAMFS/FileSystem.h>
#include <Kernel/FileSystem/SysFS/FileSystem.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/Process.h>
namespace Kernel {
struct FileSystemInitializer {
StringView short_name;
StringView name;
bool requires_open_file_description { false };
bool requires_block_device { false };
bool requires_seekable_file { false };
ErrorOr<NonnullRefPtr<FileSystem>> (*create_with_fd)(OpenFileDescription&) = nullptr;
ErrorOr<NonnullRefPtr<FileSystem>> (*create)(void) = nullptr;
};
static constexpr FileSystemInitializer s_initializers[] = {
{ "proc"sv, "ProcFS"sv, false, false, false, {}, ProcFS::try_create },
{ "devpts"sv, "DevPtsFS"sv, false, false, false, {}, DevPtsFS::try_create },
{ "sys"sv, "SysFS"sv, false, false, false, {}, SysFS::try_create },
{ "ram"sv, "RAMFS"sv, false, false, false, {}, RAMFS::try_create },
{ "ext2"sv, "Ext2FS"sv, true, true, true, Ext2FS::try_create, {} },
{ "9p"sv, "Plan9FS"sv, true, true, true, Plan9FS::try_create, {} },
{ "iso9660"sv, "ISO9660FS"sv, true, true, true, ISO9660FS::try_create, {} },
{ "fat"sv, "FATFS"sv, true, true, true, FATFS::try_create, {} },
};
static ErrorOr<NonnullRefPtr<FileSystem>> find_or_create_filesystem_instance(StringView fs_type, OpenFileDescription* possible_description)
{
for (auto& initializer_entry : s_initializers) {
if (fs_type != initializer_entry.short_name && fs_type != initializer_entry.name)
continue;
if (!initializer_entry.requires_open_file_description) {
VERIFY(initializer_entry.create);
NonnullRefPtr<FileSystem> fs = TRY(initializer_entry.create());
return fs;
}
// Note: If there's an associated file description with the filesystem, we could
// try to first find it from the VirtualFileSystem filesystem list and if it was not found,
// then create it and add it.
VERIFY(initializer_entry.create_with_fd);
if (!possible_description)
return EBADF;
OpenFileDescription& description = *possible_description;
if (initializer_entry.requires_block_device && !description.file().is_block_device())
return ENOTBLK;
if (initializer_entry.requires_seekable_file && !description.file().is_seekable()) {
dbgln("mount: this is not a seekable file");
return ENODEV;
}
return TRY(VirtualFileSystem::the().find_already_existing_or_create_file_backed_file_system(description, initializer_entry.create_with_fd));
}
return ENODEV;
}
ErrorOr<FlatPtr> Process::sys$mount(Userspace<Syscall::SC_mount_params const*> user_params)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_no_promises());
auto credentials = this->credentials();
if (!credentials->is_superuser())
return EPERM;
auto params = TRY(copy_typed_from_user(user_params));
if (params.flags & MS_REMOUNT)
return EINVAL;
if (params.flags & MS_BIND)
return EINVAL;
auto source_fd = params.source_fd;
auto target = TRY(try_copy_kstring_from_user(params.target));
auto fs_type_string = TRY(try_copy_kstring_from_user(params.fs_type));
auto fs_type = fs_type_string->view();
auto description_or_error = open_file_description(source_fd);
if (!description_or_error.is_error())
dbgln("mount {}: source fd {} @ {}", fs_type, source_fd, target);
else
dbgln("mount {} @ {}", fs_type, target);
auto target_custody = TRY(VirtualFileSystem::the().resolve_path(credentials, target->view(), current_directory()));
RefPtr<FileSystem> fs;
if (!description_or_error.is_error()) {
auto description = description_or_error.release_value();
fs = TRY(find_or_create_filesystem_instance(fs_type, description.ptr()));
auto source_pseudo_path = TRY(description->pseudo_path());
dbgln("mount: attempting to mount {} on {}", source_pseudo_path, target);
} else {
fs = TRY(find_or_create_filesystem_instance(fs_type, {}));
}
TRY(fs->initialize());
TRY(VirtualFileSystem::the().mount(*fs, target_custody, params.flags));
return 0;
}
ErrorOr<FlatPtr> Process::sys$remount(Userspace<Syscall::SC_remount_params const*> user_params)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_no_promises());
auto credentials = this->credentials();
if (!credentials->is_superuser())
return EPERM;
auto params = TRY(copy_typed_from_user(user_params));
if (params.flags & MS_REMOUNT)
return EINVAL;
if (params.flags & MS_BIND)
return EINVAL;
auto target = TRY(try_copy_kstring_from_user(params.target));
auto target_custody = TRY(VirtualFileSystem::the().resolve_path(credentials, target->view(), current_directory()));
TRY(VirtualFileSystem::the().remount(target_custody, params.flags));
return 0;
}
ErrorOr<FlatPtr> Process::sys$bindmount(Userspace<Syscall::SC_bindmount_params const*> user_params)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_no_promises());
auto credentials = this->credentials();
if (!credentials->is_superuser())
return EPERM;
auto params = TRY(copy_typed_from_user(user_params));
if (params.flags & MS_REMOUNT)
return EINVAL;
if (params.flags & MS_BIND)
return EINVAL;
auto source_fd = params.source_fd;
auto target = TRY(try_copy_kstring_from_user(params.target));
auto target_custody = TRY(VirtualFileSystem::the().resolve_path(credentials, target->view(), current_directory()));
auto description = TRY(open_file_description(source_fd));
if (!description->custody()) {
// NOTE: We only support bind-mounting inodes, not arbitrary files.
return ENODEV;
}
TRY(VirtualFileSystem::the().bind_mount(*description->custody(), target_custody, params.flags));
return 0;
}
ErrorOr<FlatPtr> Process::sys$umount(Userspace<char const*> user_mountpoint, size_t mountpoint_length)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
auto credentials = this->credentials();
if (!credentials->is_superuser())
return EPERM;
TRY(require_no_promises());
auto mountpoint = TRY(get_syscall_path_argument(user_mountpoint, mountpoint_length));
auto custody = TRY(VirtualFileSystem::the().resolve_path(credentials, mountpoint->view(), current_directory()));
TRY(VirtualFileSystem::the().unmount(*custody));
return 0;
}
}
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