FreeBSD/Linux Kernel Cross Reference
sys/sys/namei.src
1 /* $NetBSD: namei.src,v 1.60 2021/06/29 22:39:21 dholland Exp $ */
2
3 /*
4 * Copyright (c) 1985, 1989, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)namei.h 8.5 (Berkeley) 8/20/94
32 */
33
34 #ifndef _SYS_NAMEI_H_
35 #define _SYS_NAMEI_H_
36
37 #include <sys/queue.h>
38 #include <sys/mutex.h>
39
40 #if defined(_KERNEL) || defined(_MODULE)
41 #include <sys/kauth.h>
42 #include <sys/rwlock.h>
43
44 /*
45 * Abstraction for a single pathname.
46 *
47 * This contains both the pathname string and (eventually) all
48 * metadata that determines how the path is to be interpreted.
49 * It is an opaque structure; the implementation is in vfs_lookup.c.
50 *
51 * To call namei, first set up a pathbuf with pathbuf_create or
52 * pathbuf_copyin, then do NDINIT(), then call namei, then AFTER THE
53 * STRUCT NAMEIDATA IS DEAD, call pathbuf_destroy. Don't destroy the
54 * pathbuf before you've finished using the nameidata, or mysterious
55 * bad things may happen.
56 *
57 * pathbuf_assimilate is like pathbuf_create but assumes ownership of
58 * the string buffer passed in, which MUST BE of size PATH_MAX and
59 * have been allocated with PNBUF_GET(). This should only be used when
60 * absolutely necessary; e.g. nfsd uses it for loading paths from
61 * mbufs.
62 */
63 struct pathbuf;
64
65 struct pathbuf *pathbuf_create(const char *path);
66 struct pathbuf *pathbuf_assimilate(char *path);
67 int pathbuf_copyin(const char *userpath, struct pathbuf **ret);
68 void pathbuf_destroy(struct pathbuf *);
69
70 /* get a copy of the (current) path string */
71 void pathbuf_copystring(const struct pathbuf *, char *buf, size_t maxlen);
72
73 /* hold a reference copy of the original path string */
74 const char *pathbuf_stringcopy_get(struct pathbuf *);
75 void pathbuf_stringcopy_put(struct pathbuf *, const char *);
76
77 // XXX remove this
78 int pathbuf_maybe_copyin(const char *userpath, enum uio_seg seg, struct pathbuf **ret);
79
80 /*
81 * Lookup parameters: this structure describes the subset of
82 * information from the nameidata structure that is passed
83 * through the VOP interface.
84 */
85 struct componentname {
86 /*
87 * Arguments to lookup.
88 */
89 uint32_t cn_nameiop; /* namei operation */
90 uint32_t cn_flags; /* flags to namei */
91 kauth_cred_t cn_cred; /* credentials */
92 /*
93 * Shared between lookup and commit routines.
94 */
95 const char *cn_nameptr; /* pointer to looked up name */
96 size_t cn_namelen; /* length of looked up comp */
97 };
98
99 /*
100 * Encapsulation of namei parameters.
101 */
102 struct nameidata {
103 /*
104 * Arguments to namei/lookup.
105 */
106 struct vnode *ni_atdir; /* startup dir, cwd if null */
107 struct pathbuf *ni_pathbuf; /* pathname container */
108 char *ni_pnbuf; /* extra pathname buffer ref (XXX) */
109 /*
110 * Arguments to lookup.
111 */
112 struct vnode *ni_rootdir; /* logical root directory */
113 struct vnode *ni_erootdir; /* emulation root directory */
114 /*
115 * Results: returned from/manipulated by lookup
116 */
117 struct vnode *ni_vp; /* vnode of result */
118 struct vnode *ni_dvp; /* vnode of intermediate directory */
119 /*
120 * Shared between namei and lookup/commit routines.
121 */
122 size_t ni_pathlen; /* remaining chars in path */
123 const char *ni_next; /* next location in pathname */
124 unsigned int ni_loopcnt; /* count of symlinks encountered */
125 /*
126 * Lookup parameters: this structure describes the subset of
127 * information from the nameidata structure that is passed
128 * through the VOP interface.
129 */
130 struct componentname ni_cnd;
131 };
132
133 /*
134 * namei operations
135 */
136 NAMEIFL LOOKUP 0 /* perform name lookup only */
137 NAMEIFL CREATE 1 /* setup for file creation */
138 NAMEIFL DELETE 2 /* setup for file deletion */
139 NAMEIFL RENAME 3 /* setup for file renaming */
140 NAMEIFL OPMASK 3 /* mask for operation */
141 /*
142 * namei operational modifier flags, stored in ni_cnd.cn_flags
143 */
144 NAMEIFL LOCKLEAF 0x00000004 /* lock inode on return */
145 NAMEIFL LOCKPARENT 0x00000008 /* want parent vnode returned locked */
146 NAMEIFL TRYEMULROOT 0x00000010 /* try relative to emulation root
147 first */
148 NAMEIFL NOCACHE 0x00000020 /* name must not be left in cache */
149 NAMEIFL FOLLOW 0x00000040 /* follow symbolic links */
150 NAMEIFL NOFOLLOW 0x00000000 /* do not follow symbolic links
151 (pseudo) */
152 NAMEIFL EMULROOTSET 0x00000080 /* emulation root already
153 in ni_erootdir */
154 NAMEIFL LOCKSHARED 0x00000100 /* want shared locks if possible */
155 NAMEIFL NOCHROOT 0x01000000 /* no chroot on abs path lookups */
156 NAMEIFL NONEXCLHACK 0x02000000 /* open wwith O_CREAT but not O_EXCL */
157 NAMEIFL MODMASK 0x030001fc /* mask of operational modifiers */
158 /*
159 * Namei parameter descriptors.
160 */
161 NAMEIFL NOCROSSMOUNT 0x0000800 /* do not cross mount points */
162 NAMEIFL RDONLY 0x0001000 /* lookup with read-only semantics */
163 NAMEIFL ISDOTDOT 0x0002000 /* current component name is .. */
164 NAMEIFL MAKEENTRY 0x0004000 /* entry is to be added to name cache */
165 NAMEIFL ISLASTCN 0x0008000 /* this is last component of pathname */
166 NAMEIFL WILLBEDIR 0x0010000 /* new files will be dirs */
167 NAMEIFL ISWHITEOUT 0x0020000 /* found whiteout */
168 NAMEIFL DOWHITEOUT 0x0040000 /* do whiteouts */
169 NAMEIFL REQUIREDIR 0x0080000 /* must be a directory */
170 NAMEIFL CREATEDIR 0x0200000 /* trailing slashes are ok */
171 NAMEIFL PARAMASK 0x02ff800 /* mask of parameter descriptors */
172
173 /*
174 * Initialization of a nameidata structure.
175 */
176 #define NDINIT(ndp, op, flags, pathbuf) { \
177 (ndp)->ni_cnd.cn_nameiop = op; \
178 (ndp)->ni_cnd.cn_flags = flags; \
179 (ndp)->ni_atdir = NULL; \
180 (ndp)->ni_pathbuf = pathbuf; \
181 (ndp)->ni_cnd.cn_cred = kauth_cred_get(); \
182 }
183
184 /*
185 * Use this to set the start directory for openat()-type operations.
186 */
187 #define NDAT(ndp, dir) { \
188 (ndp)->ni_atdir = (dir); \
189 }
190
191 #endif
192
193 #ifdef __NAMECACHE_PRIVATE
194 #include <sys/rbtree.h>
195
196 /*
197 * For simplicity (and economy of storage), names longer than
198 * a maximum length of NCHNAMLEN are stored in non-pooled storage.
199 */
200 #define NCHNAMLEN sizeof(((struct namecache *)NULL)->nc_name)
201
202 /*
203 * Namecache entry.
204 *
205 * This structure describes the elements in the cache of recent names looked
206 * up by namei. It's carefully sized to take up 128 bytes on _LP64, to make
207 * good use of space and the CPU caches. Items used during RB tree lookup
208 * (nc_tree, nc_key) are clustered at the start of the structure.
209 *
210 * Field markings and their corresponding locks:
211 *
212 * - stable throughout the lifetime of the namecache entry
213 * d protected by nc_dvp->vi_nc_lock
214 * v protected by nc_vp->vi_nc_listlock
215 * l protected by cache_lru_lock
216 */
217 struct namecache {
218 struct rb_node nc_tree; /* d red-black tree, must be first */
219 uint64_t nc_key; /* - hashed key value */
220 TAILQ_ENTRY(namecache) nc_list; /* v nc_vp's list of cache entries */
221 TAILQ_ENTRY(namecache) nc_lru; /* l pseudo-lru chain */
222 struct vnode *nc_dvp; /* - vnode of parent of name */
223 struct vnode *nc_vp; /* - vnode the name refers to */
224 int nc_lrulist; /* l which LRU list it's on */
225 u_short nc_nlen; /* - length of the name */
226 char nc_whiteout; /* - true if a whiteout */
227 char nc_name[41]; /* - segment name */
228 };
229 #endif
230
231 #ifdef _KERNEL
232 #include <sys/pool.h>
233
234 struct mount;
235 struct cpu_info;
236
237 extern pool_cache_t pnbuf_cache; /* pathname buffer cache */
238
239 #define PNBUF_GET() ((char *)pool_cache_get(pnbuf_cache, PR_WAITOK))
240 #define PNBUF_PUT(pnb) pool_cache_put(pnbuf_cache, (void *)(pnb))
241
242 /*
243 * Typesafe flags for namei_simple/nameiat_simple.
244 *
245 * This encoding is not optimal but serves the important purpose of
246 * not being type-compatible with the regular namei flags.
247 */
248 struct namei_simple_flags_type; /* Opaque. */
249 typedef const struct namei_simple_flags_type *namei_simple_flags_t; /* Gross. */
250 extern const namei_simple_flags_t
251 NSM_NOFOLLOW_NOEMULROOT,
252 NSM_NOFOLLOW_TRYEMULROOT,
253 NSM_FOLLOW_NOEMULROOT,
254 NSM_FOLLOW_TRYEMULROOT;
255
256 /*
257 * namei(at)?_simple_* - the simple cases of namei, with no struct
258 * nameidata involved.
259 *
260 * namei_simple_kernel takes a kernel-space path as the first argument.
261 * namei_simple_user takes a user-space path as the first argument.
262 * The nameiat_simple_* variants handle relative path using the given
263 * directory vnode instead of current directory.
264 *
265 * A namei call can be converted to namei_simple_* if:
266 * - the second arg to NDINIT is LOOKUP;
267 * - it does not need the parent vnode, nd.ni_dvp;
268 * - the only flags it uses are (NO)FOLLOW and TRYEMULROOT;
269 * - it does not do anything else gross with the contents of nd.
270 */
271 int namei_simple_kernel(const char *, namei_simple_flags_t, struct vnode **);
272 int namei_simple_user(const char *, namei_simple_flags_t, struct vnode **);
273 int nameiat_simple_kernel(struct vnode *, const char *, namei_simple_flags_t,
274 struct vnode **);
275 int nameiat_simple_user(struct vnode *, const char *, namei_simple_flags_t,
276 struct vnode **);
277
278 int namei(struct nameidata *);
279 uint32_t namei_hash(const char *, const char **);
280 int lookup_for_nfsd(struct nameidata *, struct vnode *, int neverfollow);
281 int lookup_for_nfsd_index(struct nameidata *, struct vnode *);
282 int relookup(struct vnode *, struct vnode **, struct componentname *, int);
283 void cache_purge1(struct vnode *, const char *, size_t, int);
284 #define PURGE_PARENTS 1
285 #define PURGE_CHILDREN 2
286 #define cache_purge(vp) cache_purge1((vp),NULL,0,PURGE_PARENTS|PURGE_CHILDREN)
287 bool cache_lookup(struct vnode *, const char *, size_t, uint32_t, uint32_t,
288 int *, struct vnode **);
289 bool cache_lookup_raw(struct vnode *, const char *, size_t, uint32_t,
290 int *, struct vnode **);
291 bool cache_lookup_linked(struct vnode *, const char *, size_t,
292 struct vnode **, krwlock_t **, kauth_cred_t);
293 int cache_revlookup(struct vnode *, struct vnode **, char **, char *,
294 bool, accmode_t);
295 int cache_diraccess(struct vnode *, int);
296 void cache_enter(struct vnode *, struct vnode *,
297 const char *, size_t, uint32_t);
298 void cache_enter_id(struct vnode *, mode_t, uid_t, gid_t, bool);
299 bool cache_have_id(struct vnode *);
300 void cache_vnode_init(struct vnode * );
301 void cache_vnode_fini(struct vnode * );
302 void cache_cpu_init(struct cpu_info *);
303 void cache_enter_mount(struct vnode *, struct vnode *);
304 bool cache_cross_mount(struct vnode **, krwlock_t **);
305 bool cache_lookup_mount(struct vnode *, struct vnode **);
306
307 void nchinit(void);
308 void namecache_count_pass2(void);
309 void namecache_count_2passes(void);
310 void cache_purgevfs(struct mount *);
311 void namecache_print(struct vnode *, void (*)(const char *, ...)
312 __printflike(1, 2));
313
314 #endif
315
316 /*
317 * Stats on usefulness of namei caches. A couple of structures are
318 * used for counting, with members having the same names but different
319 * types. Containerize member names with the preprocessor to avoid
320 * cut-'n'-paste.
321 */
322 #define _NAMEI_CACHE_STATS(type) { \
323 type ncs_goodhits; /* hits that we can really use */ \
324 type ncs_neghits; /* negative hits that we can use */ \
325 type ncs_badhits; /* hits we must drop */ \
326 type ncs_falsehits; /* hits with id mismatch */ \
327 type ncs_miss; /* misses */ \
328 type ncs_long; /* long names that ignore cache */ \
329 type ncs_pass2; /* names found with passes == 2 */ \
330 type ncs_2passes; /* number of times we attempt it */ \
331 type ncs_revhits; /* reverse-cache hits */ \
332 type ncs_revmiss; /* reverse-cache misses */ \
333 type ncs_denied; /* access denied */ \
334 }
335
336 /*
337 * Sysctl deals with a uint64_t version of the stats and summary
338 * totals are kept that way.
339 */
340 struct nchstats _NAMEI_CACHE_STATS(uint64_t);
341
342 /* #endif !_SYS_NAMEI_H_ (generated by gennameih.awk) */
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