1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3  *
4  * Copyright (C) 2011 Novell Inc.
5  * Copyright (C) 2016 Red Hat, Inc.
6  */
7 
8 struct ovl_config {
9 	char *upperdir;
10 	char *workdir;
11 	char **lowerdirs;
12 	bool default_permissions;
13 	int redirect_mode;
14 	int verity_mode;
15 	bool index;
16 	int uuid;
17 	bool nfs_export;
18 	int xino;
19 	bool metacopy;
20 	bool userxattr;
21 	bool ovl_volatile;
22 };
23 
24 struct ovl_sb {
25 	struct super_block *sb;
26 	dev_t pseudo_dev;
27 	/* Unusable (conflicting) uuid */
28 	bool bad_uuid;
29 	/* Used as a lower layer (but maybe also as upper) */
30 	bool is_lower;
31 };
32 
33 struct ovl_layer {
34 	/* ovl_free_fs() relies on @mnt being the first member! */
35 	struct vfsmount *mnt;
36 	/* Trap in ovl inode cache */
37 	struct inode *trap;
38 	struct ovl_sb *fs;
39 	/* Index of this layer in fs root (upper idx == 0) */
40 	int idx;
41 	/* One fsid per unique underlying sb (upper fsid == 0) */
42 	int fsid;
43 };
44 
45 struct ovl_path {
46 	const struct ovl_layer *layer;
47 	struct dentry *dentry;
48 };
49 
50 struct ovl_entry {
51 	unsigned int __numlower;
52 	struct ovl_path __lowerstack[];
53 };
54 
55 /* private information held for overlayfs's superblock */
56 struct ovl_fs {
57 	unsigned int numlayer;
58 	/* Number of unique fs among layers including upper fs */
59 	unsigned int numfs;
60 	/* Number of data-only lower layers */
61 	unsigned int numdatalayer;
62 	const struct ovl_layer *layers;
63 	struct ovl_sb *fs;
64 	/* workbasedir is the path at workdir= mount option */
65 	struct dentry *workbasedir;
66 	/* workdir is the 'work' directory under workbasedir */
67 	struct dentry *workdir;
68 	/* index directory listing overlay inodes by origin file handle */
69 	struct dentry *indexdir;
70 	long namelen;
71 	/* pathnames of lower and upper dirs, for show_options */
72 	struct ovl_config config;
73 	/* creds of process who forced instantiation of super block */
74 	const struct cred *creator_cred;
75 	bool tmpfile;
76 	bool noxattr;
77 	bool nofh;
78 	/* Did we take the inuse lock? */
79 	bool upperdir_locked;
80 	bool workdir_locked;
81 	/* Traps in ovl inode cache */
82 	struct inode *workbasedir_trap;
83 	struct inode *workdir_trap;
84 	struct inode *indexdir_trap;
85 	/* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
86 	int xino_mode;
87 	/* For allocation of non-persistent inode numbers */
88 	atomic_long_t last_ino;
89 	/* Shared whiteout cache */
90 	struct dentry *whiteout;
91 	bool no_shared_whiteout;
92 	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
93 	errseq_t errseq;
94 };
95 
96 /* Number of lower layers, not including data-only layers */
ovl_numlowerlayer(struct ovl_fs * ofs)97 static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs)
98 {
99 	return ofs->numlayer - ofs->numdatalayer - 1;
100 }
101 
ovl_upper_mnt(struct ovl_fs * ofs)102 static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
103 {
104 	return ofs->layers[0].mnt;
105 }
106 
ovl_upper_mnt_idmap(struct ovl_fs * ofs)107 static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
108 {
109 	return mnt_idmap(ovl_upper_mnt(ofs));
110 }
111 
112 extern struct file_system_type ovl_fs_type;
113 
OVL_FS(struct super_block * sb)114 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
115 {
116 	if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG))
117 		WARN_ON_ONCE(sb->s_type != &ovl_fs_type);
118 
119 	return (struct ovl_fs *)sb->s_fs_info;
120 }
121 
ovl_should_sync(struct ovl_fs * ofs)122 static inline bool ovl_should_sync(struct ovl_fs *ofs)
123 {
124 	return !ofs->config.ovl_volatile;
125 }
126 
ovl_numlower(struct ovl_entry * oe)127 static inline unsigned int ovl_numlower(struct ovl_entry *oe)
128 {
129 	return oe ? oe->__numlower : 0;
130 }
131 
ovl_lowerstack(struct ovl_entry * oe)132 static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
133 {
134 	return ovl_numlower(oe) ? oe->__lowerstack : NULL;
135 }
136 
ovl_lowerpath(struct ovl_entry * oe)137 static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe)
138 {
139 	return ovl_lowerstack(oe);
140 }
141 
ovl_lowerdata(struct ovl_entry * oe)142 static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe)
143 {
144 	struct ovl_path *lowerstack = ovl_lowerstack(oe);
145 
146 	return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL;
147 }
148 
149 /* May return NULL if lazy lookup of lowerdata is needed */
ovl_lowerdata_dentry(struct ovl_entry * oe)150 static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe)
151 {
152 	struct ovl_path *lowerdata = ovl_lowerdata(oe);
153 
154 	return lowerdata ? READ_ONCE(lowerdata->dentry) : NULL;
155 }
156 
157 /* private information held for every overlayfs dentry */
OVL_E_FLAGS(struct dentry * dentry)158 static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
159 {
160 	return (unsigned long *) &dentry->d_fsdata;
161 }
162 
163 struct ovl_inode {
164 	union {
165 		struct ovl_dir_cache *cache;	/* directory */
166 		const char *lowerdata_redirect;	/* regular file */
167 	};
168 	const char *redirect;
169 	u64 version;
170 	unsigned long flags;
171 	struct inode vfs_inode;
172 	struct dentry *__upperdentry;
173 	struct ovl_entry *oe;
174 
175 	/* synchronize copy up and more */
176 	struct mutex lock;
177 };
178 
OVL_I(struct inode * inode)179 static inline struct ovl_inode *OVL_I(struct inode *inode)
180 {
181 	return container_of(inode, struct ovl_inode, vfs_inode);
182 }
183 
OVL_I_E(struct inode * inode)184 static inline struct ovl_entry *OVL_I_E(struct inode *inode)
185 {
186 	return inode ? OVL_I(inode)->oe : NULL;
187 }
188 
OVL_E(struct dentry * dentry)189 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
190 {
191 	return OVL_I_E(d_inode(dentry));
192 }
193 
ovl_upperdentry_dereference(struct ovl_inode * oi)194 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
195 {
196 	return READ_ONCE(oi->__upperdentry);
197 }
198