1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef LINUX_EXPORTFS_H
3 #define LINUX_EXPORTFS_H 1
4
5 #include <linux/types.h>
6 #include <linux/path.h>
7
8 struct dentry;
9 struct iattr;
10 struct inode;
11 struct iomap;
12 struct super_block;
13 struct vfsmount;
14
15 /* limit the handle size to NFSv4 handle size now */
16 #define MAX_HANDLE_SZ 128
17
18 /*
19 * The fileid_type identifies how the file within the filesystem is encoded.
20 * In theory this is freely set and parsed by the filesystem, but we try to
21 * stick to conventions so we can share some generic code and don't confuse
22 * sniffers like ethereal/wireshark.
23 *
24 * The filesystem must not use the value '0' or '0xff'.
25 */
26 enum fid_type {
27 /*
28 * The root, or export point, of the filesystem.
29 * (Never actually passed down to the filesystem.
30 */
31 FILEID_ROOT = 0,
32
33 /*
34 * 32bit inode number, 32 bit generation number.
35 */
36 FILEID_INO32_GEN = 1,
37
38 /*
39 * 32bit inode number, 32 bit generation number,
40 * 32 bit parent directory inode number.
41 */
42 FILEID_INO32_GEN_PARENT = 2,
43
44 /*
45 * 64 bit object ID, 64 bit root object ID,
46 * 32 bit generation number.
47 */
48 FILEID_BTRFS_WITHOUT_PARENT = 0x4d,
49
50 /*
51 * 64 bit object ID, 64 bit root object ID,
52 * 32 bit generation number,
53 * 64 bit parent object ID, 32 bit parent generation.
54 */
55 FILEID_BTRFS_WITH_PARENT = 0x4e,
56
57 /*
58 * 64 bit object ID, 64 bit root object ID,
59 * 32 bit generation number,
60 * 64 bit parent object ID, 32 bit parent generation,
61 * 64 bit parent root object ID.
62 */
63 FILEID_BTRFS_WITH_PARENT_ROOT = 0x4f,
64
65 /*
66 * 32 bit block number, 16 bit partition reference,
67 * 16 bit unused, 32 bit generation number.
68 */
69 FILEID_UDF_WITHOUT_PARENT = 0x51,
70
71 /*
72 * 32 bit block number, 16 bit partition reference,
73 * 16 bit unused, 32 bit generation number,
74 * 32 bit parent block number, 32 bit parent generation number
75 */
76 FILEID_UDF_WITH_PARENT = 0x52,
77
78 /*
79 * 64 bit checkpoint number, 64 bit inode number,
80 * 32 bit generation number.
81 */
82 FILEID_NILFS_WITHOUT_PARENT = 0x61,
83
84 /*
85 * 64 bit checkpoint number, 64 bit inode number,
86 * 32 bit generation number, 32 bit parent generation.
87 * 64 bit parent inode number.
88 */
89 FILEID_NILFS_WITH_PARENT = 0x62,
90
91 /*
92 * 32 bit generation number, 40 bit i_pos.
93 */
94 FILEID_FAT_WITHOUT_PARENT = 0x71,
95
96 /*
97 * 32 bit generation number, 40 bit i_pos,
98 * 32 bit parent generation number, 40 bit parent i_pos
99 */
100 FILEID_FAT_WITH_PARENT = 0x72,
101
102 /*
103 * 64 bit inode number, 32 bit generation number.
104 */
105 FILEID_INO64_GEN = 0x81,
106
107 /*
108 * 64 bit inode number, 32 bit generation number,
109 * 64 bit parent inode number, 32 bit parent generation.
110 */
111 FILEID_INO64_GEN_PARENT = 0x82,
112
113 /*
114 * 128 bit child FID (struct lu_fid)
115 * 128 bit parent FID (struct lu_fid)
116 */
117 FILEID_LUSTRE = 0x97,
118
119 /*
120 * 64 bit inode number, 32 bit subvolume, 32 bit generation number:
121 */
122 FILEID_BCACHEFS_WITHOUT_PARENT = 0xb1,
123 FILEID_BCACHEFS_WITH_PARENT = 0xb2,
124
125 /*
126 * 64 bit unique kernfs id
127 */
128 FILEID_KERNFS = 0xfe,
129
130 /*
131 * Filesystems must not use 0xff file ID.
132 */
133 FILEID_INVALID = 0xff,
134 };
135
136 struct fid {
137 union {
138 struct {
139 u32 ino;
140 u32 gen;
141 u32 parent_ino;
142 u32 parent_gen;
143 } i32;
144 struct {
145 u64 ino;
146 u32 gen;
147 } __packed i64;
148 struct {
149 u32 block;
150 u16 partref;
151 u16 parent_partref;
152 u32 generation;
153 u32 parent_block;
154 u32 parent_generation;
155 } udf;
156 DECLARE_FLEX_ARRAY(__u32, raw);
157 };
158 };
159
160 enum handle_to_path_flags {
161 HANDLE_CHECK_PERMS = (1 << 0),
162 HANDLE_CHECK_SUBTREE = (1 << 1),
163 };
164
165 struct handle_to_path_ctx {
166 struct path root;
167 enum handle_to_path_flags flags;
168 unsigned int fh_flags;
169 };
170
171 #define EXPORT_FH_CONNECTABLE 0x1 /* Encode file handle with parent */
172 #define EXPORT_FH_FID 0x2 /* File handle may be non-decodeable */
173 #define EXPORT_FH_DIR_ONLY 0x4 /* Only decode file handle for a directory */
174
175 /*
176 * Filesystems use only lower 8 bits of file_handle type for fid_type.
177 * name_to_handle_at() uses upper 16 bits of type as user flags to be
178 * interpreted by open_by_handle_at().
179 */
180 #define FILEID_USER_FLAGS_MASK 0xffff0000
181 #define FILEID_USER_FLAGS(type) ((type) & FILEID_USER_FLAGS_MASK)
182
183 /* Flags supported in encoded handle_type that is exported to user */
184 #define FILEID_IS_CONNECTABLE 0x10000
185 #define FILEID_IS_DIR 0x20000
186 #define FILEID_VALID_USER_FLAGS (FILEID_IS_CONNECTABLE | FILEID_IS_DIR)
187
188 /**
189 * struct export_operations - for nfsd to communicate with file systems
190 * @encode_fh: encode a file handle fragment from a dentry
191 * @fh_to_dentry: find the implied object and get a dentry for it
192 * @fh_to_parent: find the implied object's parent and get a dentry for it
193 * @get_name: find the name for a given inode in a given directory
194 * @get_parent: find the parent of a given directory
195 * @commit_metadata: commit metadata changes to stable storage
196 *
197 * See Documentation/filesystems/nfs/exporting.rst for details on how to use
198 * this interface correctly.
199 *
200 * encode_fh:
201 * @encode_fh should store in the file handle fragment @fh (using at most
202 * @max_len bytes) information that can be used by @decode_fh to recover the
203 * file referred to by the &struct dentry @de. If @flag has CONNECTABLE bit
204 * set, the encode_fh() should store sufficient information so that a good
205 * attempt can be made to find not only the file but also it's place in the
206 * filesystem. This typically means storing a reference to de->d_parent in
207 * the filehandle fragment. encode_fh() should return the fileid_type on
208 * success and on error returns 255 (if the space needed to encode fh is
209 * greater than @max_len*4 bytes). On error @max_len contains the minimum
210 * size(in 4 byte unit) needed to encode the file handle.
211 *
212 * fh_to_dentry:
213 * @fh_to_dentry is given a &struct super_block (@sb) and a file handle
214 * fragment (@fh, @fh_len). It should return a &struct dentry which refers
215 * to the same file that the file handle fragment refers to. If it cannot,
216 * it should return a %NULL pointer if the file cannot be found, or an
217 * %ERR_PTR error code of %ENOMEM if a memory allocation failure occurred.
218 * Any other error code is treated like %NULL, and will cause an %ESTALE error
219 * for callers of exportfs_decode_fh().
220 * Any suitable dentry can be returned including, if necessary, a new dentry
221 * created with d_alloc_root. The caller can then find any other extant
222 * dentries by following the d_alias links.
223 *
224 * fh_to_parent:
225 * Same as @fh_to_dentry, except that it returns a pointer to the parent
226 * dentry if it was encoded into the filehandle fragment by @encode_fh.
227 *
228 * get_name:
229 * @get_name should find a name for the given @child in the given @parent
230 * directory. The name should be stored in the @name (with the
231 * understanding that it is already pointing to a %NAME_MAX+1 sized
232 * buffer. get_name() should return %0 on success, a negative error code
233 * or error. @get_name will be called without @parent->i_mutex held.
234 *
235 * get_parent:
236 * @get_parent should find the parent directory for the given @child which
237 * is also a directory. In the event that it cannot be found, or storage
238 * space cannot be allocated, a %ERR_PTR should be returned.
239 *
240 * permission:
241 * Allow filesystems to specify a custom permission function.
242 *
243 * open:
244 * Allow filesystems to specify a custom open function.
245 *
246 * commit_metadata:
247 * @commit_metadata should commit metadata changes to stable storage.
248 *
249 * Locking rules:
250 * get_parent is called with child->d_inode->i_mutex down
251 * get_name is not (which is possibly inconsistent)
252 */
253
254 struct export_operations {
255 int (*encode_fh)(struct inode *inode, __u32 *fh, int *max_len,
256 struct inode *parent);
257 struct dentry * (*fh_to_dentry)(struct super_block *sb, struct fid *fid,
258 int fh_len, int fh_type);
259 struct dentry * (*fh_to_parent)(struct super_block *sb, struct fid *fid,
260 int fh_len, int fh_type);
261 int (*get_name)(struct dentry *parent, char *name,
262 struct dentry *child);
263 struct dentry * (*get_parent)(struct dentry *child);
264 int (*commit_metadata)(struct inode *inode);
265
266 int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
267 int (*map_blocks)(struct inode *inode, loff_t offset,
268 u64 len, struct iomap *iomap,
269 bool write, u32 *device_generation);
270 int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
271 int nr_iomaps, struct iattr *iattr);
272 int (*permission)(struct handle_to_path_ctx *ctx, unsigned int oflags);
273 struct file * (*open)(struct path *path, unsigned int oflags);
274 #define EXPORT_OP_NOWCC (0x1) /* don't collect v3 wcc data */
275 #define EXPORT_OP_NOSUBTREECHK (0x2) /* no subtree checking */
276 #define EXPORT_OP_CLOSE_BEFORE_UNLINK (0x4) /* close files before unlink */
277 #define EXPORT_OP_REMOTE_FS (0x8) /* Filesystem is remote */
278 #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply
279 atomic attribute updates
280 */
281 #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */
282 #define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */
283 unsigned long flags;
284 };
285
286 extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
287 int *max_len, struct inode *parent,
288 int flags);
289 extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
290 int *max_len, int flags);
291
exportfs_can_encode_fid(const struct export_operations * nop)292 static inline bool exportfs_can_encode_fid(const struct export_operations *nop)
293 {
294 return !nop || nop->encode_fh;
295 }
296
exportfs_can_decode_fh(const struct export_operations * nop)297 static inline bool exportfs_can_decode_fh(const struct export_operations *nop)
298 {
299 return nop && nop->fh_to_dentry;
300 }
301
exportfs_can_encode_fh(const struct export_operations * nop,int fh_flags)302 static inline bool exportfs_can_encode_fh(const struct export_operations *nop,
303 int fh_flags)
304 {
305 /*
306 * If a non-decodeable file handle was requested, we only need to make
307 * sure that filesystem did not opt-out of encoding fid.
308 */
309 if (fh_flags & EXPORT_FH_FID)
310 return exportfs_can_encode_fid(nop);
311
312 /*
313 * If a decodeable file handle was requested, we need to make sure that
314 * filesystem can also decode file handles.
315 */
316 return exportfs_can_decode_fh(nop);
317 }
318
exportfs_encode_fid(struct inode * inode,struct fid * fid,int * max_len)319 static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid,
320 int *max_len)
321 {
322 return exportfs_encode_inode_fh(inode, fid, max_len, NULL,
323 EXPORT_FH_FID);
324 }
325
326 extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt,
327 struct fid *fid, int fh_len,
328 int fileid_type,
329 unsigned int flags,
330 int (*acceptable)(void *, struct dentry *),
331 void *context);
332 extern struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
333 int fh_len, int fileid_type, int (*acceptable)(void *, struct dentry *),
334 void *context);
335
336 /*
337 * Generic helpers for filesystems.
338 */
339 int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len,
340 struct inode *parent);
341 struct dentry *generic_fh_to_dentry(struct super_block *sb,
342 struct fid *fid, int fh_len, int fh_type,
343 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
344 struct dentry *generic_fh_to_parent(struct super_block *sb,
345 struct fid *fid, int fh_len, int fh_type,
346 struct inode *(*get_inode) (struct super_block *sb, u64 ino, u32 gen));
347
348 #endif /* LINUX_EXPORTFS_H */
349