1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
4  *
5  * This file describes the layout of the file handles as passed
6  * over the wire.
7  */
8 #ifndef _LINUX_NFSD_NFSFH_H
9 #define _LINUX_NFSD_NFSFH_H
10 
11 #include <linux/crc32.h>
12 #include <linux/sunrpc/svc.h>
13 #include <linux/iversion.h>
14 #include <linux/exportfs.h>
15 #include <linux/nfs4.h>
16 
17 /*
18  * The file handle starts with a sequence of four-byte words.
19  * The first word contains a version number (1) and three descriptor bytes
20  * that tell how the remaining 3 variable length fields should be handled.
21  * These three bytes are auth_type, fsid_type and fileid_type.
22  *
23  * All four-byte values are in host-byte-order.
24  *
25  * The auth_type field is deprecated and must be set to 0.
26  *
27  * The fsid_type identifies how the filesystem (or export point) is
28  *    encoded.
29  *  Current values:
30  *     0  - 4 byte device id (ms-2-bytes major, ls-2-bytes minor), 4byte inode number
31  *        NOTE: we cannot use the kdev_t device id value, because kdev_t.h
32  *              says we mustn't.  We must break it up and reassemble.
33  *     1  - 4 byte user specified identifier
34  *     2  - 4 byte major, 4 byte minor, 4 byte inode number - DEPRECATED
35  *     3  - 4 byte device id, encoded for user-space, 4 byte inode number
36  *     4  - 4 byte inode number and 4 byte uuid
37  *     5  - 8 byte uuid
38  *     6  - 16 byte uuid
39  *     7  - 8 byte inode number and 16 byte uuid
40  *
41  * The fileid_type identifies how the file within the filesystem is encoded.
42  *   The values for this field are filesystem specific, exccept that
43  *   filesystems must not use the values '0' or '0xff'. 'See enum fid_type'
44  *   in include/linux/exportfs.h for currently registered values.
45  */
46 
47 struct knfsd_fh {
48 	unsigned int	fh_size;	/*
49 					 * Points to the current size while
50 					 * building a new file handle.
51 					 */
52 	union {
53 		char			fh_raw[NFS4_FHSIZE];
54 		struct {
55 			u8		fh_version;	/* == 1 */
56 			u8		fh_auth_type;	/* deprecated */
57 			u8		fh_fsid_type;
58 			u8		fh_fileid_type;
59 			u32		fh_fsid[]; /* flexible-array member */
60 		};
61 	};
62 };
63 
ino_t_to_u32(ino_t ino)64 static inline __u32 ino_t_to_u32(ino_t ino)
65 {
66 	return (__u32) ino;
67 }
68 
u32_to_ino_t(__u32 uino)69 static inline ino_t u32_to_ino_t(__u32 uino)
70 {
71 	return (ino_t) uino;
72 }
73 
74 /*
75  * This is the internal representation of an NFS handle used in knfsd.
76  * pre_mtime/post_version will be used to support wcc_attr's in NFSv3.
77  */
78 typedef struct svc_fh {
79 	struct knfsd_fh		fh_handle;	/* FH data */
80 	int			fh_maxsize;	/* max size for fh_handle */
81 	struct dentry *		fh_dentry;	/* validated dentry */
82 	struct svc_export *	fh_export;	/* export pointer */
83 
84 	bool			fh_want_write;	/* remount protection taken */
85 	bool			fh_no_wcc;	/* no wcc data needed */
86 	bool			fh_no_atomic_attr;
87 						/*
88 						 * wcc data is not atomic with
89 						 * operation
90 						 */
91 	int			fh_flags;	/* FH flags */
92 	bool			fh_post_saved;	/* post-op attrs saved */
93 	bool			fh_pre_saved;	/* pre-op attrs saved */
94 
95 	/* Pre-op attributes saved when inode is locked */
96 	__u64			fh_pre_size;	/* size before operation */
97 	struct timespec64	fh_pre_mtime;	/* mtime before oper */
98 	struct timespec64	fh_pre_ctime;	/* ctime before oper */
99 	/*
100 	 * pre-op nfsv4 change attr: note must check IS_I_VERSION(inode)
101 	 *  to find out if it is valid.
102 	 */
103 	u64			fh_pre_change;
104 
105 	/* Post-op attributes saved in fh_fill_post_attrs() */
106 	struct kstat		fh_post_attr;	/* full attrs after operation */
107 	u64			fh_post_change; /* nfsv4 change; see above */
108 } svc_fh;
109 #define NFSD4_FH_FOREIGN (1<<0)
110 #define SET_FH_FLAG(c, f) ((c)->fh_flags |= (f))
111 #define HAS_FH_FLAG(c, f) ((c)->fh_flags & (f))
112 
113 enum nfsd_fsid {
114 	FSID_DEV = 0,
115 	FSID_NUM,
116 	FSID_MAJOR_MINOR,
117 	FSID_ENCODE_DEV,
118 	FSID_UUID4_INUM,
119 	FSID_UUID8,
120 	FSID_UUID16,
121 	FSID_UUID16_INUM,
122 };
123 
124 enum fsid_source {
125 	FSIDSOURCE_DEV,
126 	FSIDSOURCE_FSID,
127 	FSIDSOURCE_UUID,
128 };
129 extern enum fsid_source fsid_source(const struct svc_fh *fhp);
130 
131 
132 /*
133  * This might look a little large to "inline" but in all calls except
134  * one, 'vers' is constant so moste of the function disappears.
135  *
136  * In some cases the values are considered to be host endian and in
137  * others, net endian. fsidv is always considered to be u32 as the
138  * callers don't know which it will be. So we must use __force to keep
139  * sparse from complaining. Since these values are opaque to the
140  * client, that shouldn't be a problem.
141  */
mk_fsid(int vers,u32 * fsidv,dev_t dev,ino_t ino,u32 fsid,unsigned char * uuid)142 static inline void mk_fsid(int vers, u32 *fsidv, dev_t dev, ino_t ino,
143 			   u32 fsid, unsigned char *uuid)
144 {
145 	u32 *up;
146 	switch(vers) {
147 	case FSID_DEV:
148 		fsidv[0] = (__force __u32)htonl((MAJOR(dev)<<16) |
149 				 MINOR(dev));
150 		fsidv[1] = ino_t_to_u32(ino);
151 		break;
152 	case FSID_NUM:
153 		fsidv[0] = fsid;
154 		break;
155 	case FSID_MAJOR_MINOR:
156 		fsidv[0] = (__force __u32)htonl(MAJOR(dev));
157 		fsidv[1] = (__force __u32)htonl(MINOR(dev));
158 		fsidv[2] = ino_t_to_u32(ino);
159 		break;
160 
161 	case FSID_ENCODE_DEV:
162 		fsidv[0] = new_encode_dev(dev);
163 		fsidv[1] = ino_t_to_u32(ino);
164 		break;
165 
166 	case FSID_UUID4_INUM:
167 		/* 4 byte fsid and inode number */
168 		up = (u32*)uuid;
169 		fsidv[0] = ino_t_to_u32(ino);
170 		fsidv[1] = up[0] ^ up[1] ^ up[2] ^ up[3];
171 		break;
172 
173 	case FSID_UUID8:
174 		/* 8 byte fsid  */
175 		up = (u32*)uuid;
176 		fsidv[0] = up[0] ^ up[2];
177 		fsidv[1] = up[1] ^ up[3];
178 		break;
179 
180 	case FSID_UUID16:
181 		/* 16 byte fsid - NFSv3+ only */
182 		memcpy(fsidv, uuid, 16);
183 		break;
184 
185 	case FSID_UUID16_INUM:
186 		/* 8 byte inode and 16 byte fsid */
187 		*(u64*)fsidv = (u64)ino;
188 		memcpy(fsidv+2, uuid, 16);
189 		break;
190 	default: BUG();
191 	}
192 }
193 
key_len(int type)194 static inline int key_len(int type)
195 {
196 	switch(type) {
197 	case FSID_DEV:		return 8;
198 	case FSID_NUM: 		return 4;
199 	case FSID_MAJOR_MINOR:	return 12;
200 	case FSID_ENCODE_DEV:	return 8;
201 	case FSID_UUID4_INUM:	return 8;
202 	case FSID_UUID8:	return 8;
203 	case FSID_UUID16:	return 16;
204 	case FSID_UUID16_INUM:	return 24;
205 	default: return 0;
206 	}
207 }
208 
209 /*
210  * Shorthand for dprintk()'s
211  */
212 extern char * SVCFH_fmt(struct svc_fh *fhp);
213 
214 /*
215  * Function prototypes
216  */
217 __be32	fh_verify(struct svc_rqst *, struct svc_fh *, umode_t, int);
218 __be32	fh_compose(struct svc_fh *, struct svc_export *, struct dentry *, struct svc_fh *);
219 __be32	fh_update(struct svc_fh *);
220 void	fh_put(struct svc_fh *);
221 
222 static __inline__ struct svc_fh *
fh_copy(struct svc_fh * dst,struct svc_fh * src)223 fh_copy(struct svc_fh *dst, struct svc_fh *src)
224 {
225 	WARN_ON(src->fh_dentry);
226 
227 	*dst = *src;
228 	return dst;
229 }
230 
231 static inline void
fh_copy_shallow(struct knfsd_fh * dst,struct knfsd_fh * src)232 fh_copy_shallow(struct knfsd_fh *dst, struct knfsd_fh *src)
233 {
234 	dst->fh_size = src->fh_size;
235 	memcpy(&dst->fh_raw, &src->fh_raw, src->fh_size);
236 }
237 
238 static __inline__ struct svc_fh *
fh_init(struct svc_fh * fhp,int maxsize)239 fh_init(struct svc_fh *fhp, int maxsize)
240 {
241 	memset(fhp, 0, sizeof(*fhp));
242 	fhp->fh_maxsize = maxsize;
243 	return fhp;
244 }
245 
fh_match(struct knfsd_fh * fh1,struct knfsd_fh * fh2)246 static inline bool fh_match(struct knfsd_fh *fh1, struct knfsd_fh *fh2)
247 {
248 	if (fh1->fh_size != fh2->fh_size)
249 		return false;
250 	if (memcmp(fh1->fh_raw, fh2->fh_raw, fh1->fh_size) != 0)
251 		return false;
252 	return true;
253 }
254 
fh_fsid_match(struct knfsd_fh * fh1,struct knfsd_fh * fh2)255 static inline bool fh_fsid_match(struct knfsd_fh *fh1, struct knfsd_fh *fh2)
256 {
257 	if (fh1->fh_fsid_type != fh2->fh_fsid_type)
258 		return false;
259 	if (memcmp(fh1->fh_fsid, fh2->fh_fsid, key_len(fh1->fh_fsid_type)) != 0)
260 		return false;
261 	return true;
262 }
263 
264 #ifdef CONFIG_CRC32
265 /**
266  * knfsd_fh_hash - calculate the crc32 hash for the filehandle
267  * @fh - pointer to filehandle
268  *
269  * returns a crc32 hash for the filehandle that is compatible with
270  * the one displayed by "wireshark".
271  */
knfsd_fh_hash(const struct knfsd_fh * fh)272 static inline u32 knfsd_fh_hash(const struct knfsd_fh *fh)
273 {
274 	return ~crc32_le(0xFFFFFFFF, fh->fh_raw, fh->fh_size);
275 }
276 #else
knfsd_fh_hash(const struct knfsd_fh * fh)277 static inline u32 knfsd_fh_hash(const struct knfsd_fh *fh)
278 {
279 	return 0;
280 }
281 #endif
282 
283 /**
284  * fh_clear_pre_post_attrs - Reset pre/post attributes
285  * @fhp: file handle to be updated
286  *
287  */
fh_clear_pre_post_attrs(struct svc_fh * fhp)288 static inline void fh_clear_pre_post_attrs(struct svc_fh *fhp)
289 {
290 	fhp->fh_post_saved = false;
291 	fhp->fh_pre_saved = false;
292 }
293 
294 /*
295  * We could use i_version alone as the change attribute.  However,
296  * i_version can go backwards after a reboot.  On its own that doesn't
297  * necessarily cause a problem, but if i_version goes backwards and then
298  * is incremented again it could reuse a value that was previously used
299  * before boot, and a client who queried the two values might
300  * incorrectly assume nothing changed.
301  *
302  * By using both ctime and the i_version counter we guarantee that as
303  * long as time doesn't go backwards we never reuse an old value.
304  */
nfsd4_change_attribute(struct kstat * stat,struct inode * inode)305 static inline u64 nfsd4_change_attribute(struct kstat *stat,
306 					 struct inode *inode)
307 {
308 	if (inode->i_sb->s_export_op->fetch_iversion)
309 		return inode->i_sb->s_export_op->fetch_iversion(inode);
310 	else if (IS_I_VERSION(inode)) {
311 		u64 chattr;
312 
313 		chattr =  stat->ctime.tv_sec;
314 		chattr <<= 30;
315 		chattr += stat->ctime.tv_nsec;
316 		chattr += inode_query_iversion(inode);
317 		return chattr;
318 	} else
319 		return time_to_chattr(&stat->ctime);
320 }
321 
322 extern void fh_fill_pre_attrs(struct svc_fh *fhp);
323 extern void fh_fill_post_attrs(struct svc_fh *fhp);
324 extern void fh_fill_both_attrs(struct svc_fh *fhp);
325 #endif /* _LINUX_NFSD_NFSFH_H */
326