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 	/* xwhiteouts were found on this layer */
44 	bool has_xwhiteouts;
45 };
46 
47 struct ovl_path {
48 	const struct ovl_layer *layer;
49 	struct dentry *dentry;
50 };
51 
52 struct ovl_entry {
53 	unsigned int __numlower;
54 	struct ovl_path __lowerstack[];
55 };
56 
57 /* private information held for overlayfs's superblock */
58 struct ovl_fs {
59 	unsigned int numlayer;
60 	/* Number of unique fs among layers including upper fs */
61 	unsigned int numfs;
62 	/* Number of data-only lower layers */
63 	unsigned int numdatalayer;
64 	struct ovl_layer *layers;
65 	struct ovl_sb *fs;
66 	/* workbasedir is the path at workdir= mount option */
67 	struct dentry *workbasedir;
68 	/* workdir is the 'work' or 'index' directory under workbasedir */
69 	struct dentry *workdir;
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 	/* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
85 	int xino_mode;
86 	/* For allocation of non-persistent inode numbers */
87 	atomic_long_t last_ino;
88 	/* Shared whiteout cache */
89 	struct dentry *whiteout;
90 	bool no_shared_whiteout;
91 	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
92 	errseq_t errseq;
93 };
94 
95 /* Number of lower layers, not including data-only layers */
ovl_numlowerlayer(struct ovl_fs * ofs)96 static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs)
97 {
98 	return ofs->numlayer - ofs->numdatalayer - 1;
99 }
100 
ovl_upper_mnt(struct ovl_fs * ofs)101 static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
102 {
103 	return ofs->layers[0].mnt;
104 }
105 
ovl_upper_mnt_idmap(struct ovl_fs * ofs)106 static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
107 {
108 	return mnt_idmap(ovl_upper_mnt(ofs));
109 }
110 
111 extern struct file_system_type ovl_fs_type;
112 
OVL_FS(struct super_block * sb)113 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
114 {
115 	if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG))
116 		WARN_ON_ONCE(sb->s_type != &ovl_fs_type);
117 
118 	return (struct ovl_fs *)sb->s_fs_info;
119 }
120 
ovl_should_sync(struct ovl_fs * ofs)121 static inline bool ovl_should_sync(struct ovl_fs *ofs)
122 {
123 	return !ofs->config.ovl_volatile;
124 }
125 
ovl_numlower(struct ovl_entry * oe)126 static inline unsigned int ovl_numlower(struct ovl_entry *oe)
127 {
128 	return oe ? oe->__numlower : 0;
129 }
130 
ovl_lowerstack(struct ovl_entry * oe)131 static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
132 {
133 	return ovl_numlower(oe) ? oe->__lowerstack : NULL;
134 }
135 
ovl_lowerpath(struct ovl_entry * oe)136 static inline struct ovl_path *ovl_lowerpath(struct ovl_entry *oe)
137 {
138 	return ovl_lowerstack(oe);
139 }
140 
ovl_lowerdata(struct ovl_entry * oe)141 static inline struct ovl_path *ovl_lowerdata(struct ovl_entry *oe)
142 {
143 	struct ovl_path *lowerstack = ovl_lowerstack(oe);
144 
145 	return lowerstack ? &lowerstack[oe->__numlower - 1] : NULL;
146 }
147 
148 /* May return NULL if lazy lookup of lowerdata is needed */
ovl_lowerdata_dentry(struct ovl_entry * oe)149 static inline struct dentry *ovl_lowerdata_dentry(struct ovl_entry *oe)
150 {
151 	struct ovl_path *lowerdata = ovl_lowerdata(oe);
152 
153 	return lowerdata ? READ_ONCE(lowerdata->dentry) : NULL;
154 }
155 
156 /* private information held for every overlayfs dentry */
OVL_E_FLAGS(struct dentry * dentry)157 static inline unsigned long *OVL_E_FLAGS(struct dentry *dentry)
158 {
159 	return (unsigned long *) &dentry->d_fsdata;
160 }
161 
162 struct ovl_inode {
163 	union {
164 		struct ovl_dir_cache *cache;	/* directory */
165 		const char *lowerdata_redirect;	/* regular file */
166 	};
167 	const char *redirect;
168 	u64 version;
169 	unsigned long flags;
170 	struct inode vfs_inode;
171 	struct dentry *__upperdentry;
172 	struct ovl_entry *oe;
173 
174 	/* synchronize copy up and more */
175 	struct mutex lock;
176 };
177 
OVL_I(struct inode * inode)178 static inline struct ovl_inode *OVL_I(struct inode *inode)
179 {
180 	return container_of(inode, struct ovl_inode, vfs_inode);
181 }
182 
OVL_I_E(struct inode * inode)183 static inline struct ovl_entry *OVL_I_E(struct inode *inode)
184 {
185 	return inode ? OVL_I(inode)->oe : NULL;
186 }
187 
OVL_E(struct dentry * dentry)188 static inline struct ovl_entry *OVL_E(struct dentry *dentry)
189 {
190 	return OVL_I_E(d_inode(dentry));
191 }
192 
ovl_upperdentry_dereference(struct ovl_inode * oi)193 static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
194 {
195 	return READ_ONCE(oi->__upperdentry);
196 }
197