jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#pragma once
8
9#include <AK/Badge.h>
10#include <AK/Error.h>
11#include <AK/Function.h>
12#include <AK/HashMap.h>
13#include <AK/OwnPtr.h>
14#include <AK/RefPtr.h>
15#include <Kernel/FileSystem/FileBackedFileSystem.h>
16#include <Kernel/FileSystem/FileSystem.h>
17#include <Kernel/FileSystem/InodeIdentifier.h>
18#include <Kernel/FileSystem/InodeMetadata.h>
19#include <Kernel/FileSystem/Mount.h>
20#include <Kernel/FileSystem/UnveilNode.h>
21#include <Kernel/Forward.h>
22#include <Kernel/Library/LockRefPtr.h>
23#include <Kernel/Locking/SpinlockProtected.h>
24
25namespace Kernel {
26
27// Kernel internal options.
28#define O_NOFOLLOW_NOERROR (1 << 29)
29#define O_UNLINK_INTERNAL (1 << 30)
30
31struct UidAndGid {
32 UserID uid;
33 GroupID gid;
34};
35
36enum class AccessFlags {
37 None = 0,
38 EffectiveAccess = 1 << 0,
39 DoNotFollowSymlinks = 1 << 1,
40};
41
42AK_ENUM_BITWISE_OPERATORS(AccessFlags);
43
44class VirtualFileSystem {
45public:
46 // Required to be at least 8 by POSIX
47 // https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html
48 static constexpr int symlink_recursion_limit = 8;
49
50 static void initialize();
51 static VirtualFileSystem& the();
52
53 VirtualFileSystem();
54 ~VirtualFileSystem();
55
56 ErrorOr<void> mount_root(FileSystem&);
57 ErrorOr<void> mount(FileSystem&, Custody& mount_point, int flags);
58 ErrorOr<void> bind_mount(Custody& source, Custody& mount_point, int flags);
59 ErrorOr<void> remount(Custody& mount_point, int new_flags);
60 ErrorOr<void> unmount(Custody& mount_point);
61
62 ErrorOr<NonnullRefPtr<OpenFileDescription>> open(Credentials const&, StringView path, int options, mode_t mode, Custody& base, Optional<UidAndGid> = {});
63 ErrorOr<NonnullRefPtr<OpenFileDescription>> open(Process const&, Credentials const&, StringView path, int options, mode_t mode, Custody& base, Optional<UidAndGid> = {});
64 ErrorOr<NonnullRefPtr<OpenFileDescription>> create(Credentials const&, StringView path, int options, mode_t mode, Custody& parent_custody, Optional<UidAndGid> = {});
65 ErrorOr<NonnullRefPtr<OpenFileDescription>> create(Process const&, Credentials const&, StringView path, int options, mode_t mode, Custody& parent_custody, Optional<UidAndGid> = {});
66 ErrorOr<void> mkdir(Credentials const&, StringView path, mode_t mode, Custody& base);
67 ErrorOr<void> link(Credentials const&, StringView old_path, StringView new_path, Custody& base);
68 ErrorOr<void> unlink(Credentials const&, StringView path, Custody& base);
69 ErrorOr<void> symlink(Credentials const&, StringView target, StringView linkpath, Custody& base);
70 ErrorOr<void> rmdir(Credentials const&, StringView path, Custody& base);
71 ErrorOr<void> chmod(Credentials const&, StringView path, mode_t, Custody& base, int options = 0);
72 ErrorOr<void> chmod(Credentials const&, Custody&, mode_t);
73 ErrorOr<void> chown(Credentials const&, StringView path, UserID, GroupID, Custody& base, int options);
74 ErrorOr<void> chown(Credentials const&, Custody&, UserID, GroupID);
75 ErrorOr<void> access(Credentials const&, StringView path, int mode, Custody& base, AccessFlags);
76 ErrorOr<InodeMetadata> lookup_metadata(Credentials const&, StringView path, Custody& base, int options = 0);
77 ErrorOr<void> utime(Credentials const&, StringView path, Custody& base, time_t atime, time_t mtime);
78 ErrorOr<void> utimensat(Credentials const&, StringView path, Custody& base, timespec const& atime, timespec const& mtime, int options = 0);
79 ErrorOr<void> rename(Credentials const&, Custody& old_base, StringView oldpath, Custody& new_base, StringView newpath);
80 ErrorOr<void> mknod(Credentials const&, StringView path, mode_t, dev_t, Custody& base);
81 ErrorOr<NonnullRefPtr<Custody>> open_directory(Credentials const&, StringView path, Custody& base);
82
83 ErrorOr<void> for_each_mount(Function<ErrorOr<void>(Mount const&)>) const;
84
85 ErrorOr<NonnullLockRefPtr<FileBackedFileSystem>> find_already_existing_or_create_file_backed_file_system(OpenFileDescription& description, Function<ErrorOr<NonnullLockRefPtr<FileSystem>>(OpenFileDescription&)> callback);
86
87 InodeIdentifier root_inode_id() const;
88
89 void sync_filesystems();
90 void lock_all_filesystems();
91
92 static void sync();
93
94 NonnullRefPtr<Custody> root_custody();
95 ErrorOr<NonnullRefPtr<Custody>> resolve_path(Credentials const&, StringView path, NonnullRefPtr<Custody> base, RefPtr<Custody>* out_parent = nullptr, int options = 0, int symlink_recursion_level = 0);
96 ErrorOr<NonnullRefPtr<Custody>> resolve_path(Process const&, Credentials const&, StringView path, NonnullRefPtr<Custody> base, RefPtr<Custody>* out_parent = nullptr, int options = 0, int symlink_recursion_level = 0);
97 ErrorOr<NonnullRefPtr<Custody>> resolve_path_without_veil(Credentials const&, StringView path, NonnullRefPtr<Custody> base, RefPtr<Custody>* out_parent = nullptr, int options = 0, int symlink_recursion_level = 0);
98
99private:
100 friend class OpenFileDescription;
101
102 UnveilNode const& find_matching_unveiled_path(Process const&, StringView path);
103 ErrorOr<void> validate_path_against_process_veil(Process const&, StringView path, int options);
104 ErrorOr<void> validate_path_against_process_veil(Process const& process, Custody const& custody, int options);
105 ErrorOr<void> validate_path_against_process_veil(Custody const& path, int options);
106 ErrorOr<void> validate_path_against_process_veil(StringView path, int options);
107
108 bool is_vfs_root(InodeIdentifier) const;
109
110 ErrorOr<void> traverse_directory_inode(Inode&, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>);
111
112 bool mount_point_exists_at_inode(InodeIdentifier inode);
113
114 // FIXME: These functions are totally unsafe as someone could unmount the returned Mount underneath us.
115 Mount* find_mount_for_host(InodeIdentifier);
116 Mount* find_mount_for_guest(InodeIdentifier);
117
118 RefPtr<Inode> m_root_inode;
119
120 SpinlockProtected<RefPtr<Custody>, LockRank::None> m_root_custody {};
121
122 SpinlockProtected<IntrusiveList<&Mount::m_vfs_list_node>, LockRank::None> m_mounts {};
123 SpinlockProtected<IntrusiveList<&FileBackedFileSystem::m_file_backed_file_system_node>, LockRank::None> m_file_backed_file_systems_list {};
124 SpinlockProtected<IntrusiveList<&FileSystem::m_file_system_node>, LockRank::FileSystem> m_file_systems_list {};
125};
126
127}