1 /* $OpenBSD: linux_getcwd.c,v 1.2 2001/05/16 12:50:21 ho Exp $ */
2 /* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */
3 /*-
4 * Copyright (c) 1999 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Bill Sommerfeld.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the NetBSD
21 * Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 * contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD: releng/8.4/sys/compat/linux/linux_getcwd.c 193511 2009-06-05 14:55:22Z rwatson $");
41
42 #include "opt_compat.h"
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/namei.h>
47 #include <sys/filedesc.h>
48 #include <sys/kernel.h>
49 #include <sys/file.h>
50 #include <sys/stat.h>
51 #include <sys/syscallsubr.h>
52 #include <sys/vnode.h>
53 #include <sys/mount.h>
54 #include <sys/proc.h>
55 #include <sys/uio.h>
56 #include <sys/malloc.h>
57 #include <sys/dirent.h>
58 #include <ufs/ufs/dir.h> /* XXX only for DIRBLKSIZ */
59
60 #ifdef COMPAT_LINUX32
61 #include <machine/../linux32/linux.h>
62 #include <machine/../linux32/linux32_proto.h>
63 #else
64 #include <machine/../linux/linux.h>
65 #include <machine/../linux/linux_proto.h>
66 #endif
67 #include <compat/linux/linux_util.h>
68
69 #include <security/mac/mac_framework.h>
70
71 static int
72 linux_getcwd_scandir(struct vnode **, struct vnode **,
73 char **, char *, struct thread *);
74 static int
75 linux_getcwd_common(struct vnode *, struct vnode *,
76 char **, char *, int, int, struct thread *);
77
78 #define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
79
80 /*
81 * Vnode variable naming conventions in this file:
82 *
83 * rvp: the current root we're aiming towards.
84 * lvp, *lvpp: the "lower" vnode
85 * uvp, *uvpp: the "upper" vnode.
86 *
87 * Since all the vnodes we're dealing with are directories, and the
88 * lookups are going *up* in the filesystem rather than *down*, the
89 * usual "pvp" (parent) or "dvp" (directory) naming conventions are
90 * too confusing.
91 */
92
93 /*
94 * XXX Will infinite loop in certain cases if a directory read reliably
95 * returns EINVAL on last block.
96 * XXX is EINVAL the right thing to return if a directory is malformed?
97 */
98
99 /*
100 * XXX Untested vs. mount -o union; probably does the wrong thing.
101 */
102
103 /*
104 * Find parent vnode of *lvpp, return in *uvpp
105 *
106 * If we care about the name, scan it looking for name of directory
107 * entry pointing at lvp.
108 *
109 * Place the name in the buffer which starts at bufp, immediately
110 * before *bpp, and move bpp backwards to point at the start of it.
111 *
112 * On entry, *lvpp is a locked vnode reference; on exit, it is vput and NULL'ed
113 * On exit, *uvpp is either NULL or is a locked vnode reference.
114 */
115 static int
116 linux_getcwd_scandir(lvpp, uvpp, bpp, bufp, td)
117 struct vnode **lvpp;
118 struct vnode **uvpp;
119 char **bpp;
120 char *bufp;
121 struct thread *td;
122 {
123 int error = 0;
124 int eofflag;
125 off_t off;
126 int tries;
127 struct uio uio;
128 struct iovec iov;
129 char *dirbuf = NULL;
130 int dirbuflen;
131 ino_t fileno;
132 struct vattr va;
133 struct vnode *uvp = NULL;
134 struct vnode *lvp = *lvpp;
135 struct componentname cn;
136 int len, reclen;
137 tries = 0;
138
139 /*
140 * If we want the filename, get some info we need while the
141 * current directory is still locked.
142 */
143 if (bufp != NULL) {
144 error = VOP_GETATTR(lvp, &va, td->td_ucred);
145 if (error) {
146 vput(lvp);
147 *lvpp = NULL;
148 *uvpp = NULL;
149 return error;
150 }
151 }
152
153 /*
154 * Ok, we have to do it the hard way..
155 * Next, get parent vnode using lookup of ..
156 */
157 cn.cn_nameiop = LOOKUP;
158 cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY;
159 cn.cn_thread = td;
160 cn.cn_cred = td->td_ucred;
161 cn.cn_pnbuf = NULL;
162 cn.cn_nameptr = "..";
163 cn.cn_namelen = 2;
164 cn.cn_consume = 0;
165 cn.cn_lkflags = LK_SHARED;
166
167 /*
168 * At this point, lvp is locked and will be unlocked by the lookup.
169 * On successful return, *uvpp will be locked
170 */
171 #ifdef MAC
172 error = mac_vnode_check_lookup(td->td_ucred, lvp, &cn);
173 if (error == 0)
174 #endif
175 error = VOP_LOOKUP(lvp, uvpp, &cn);
176 if (error) {
177 vput(lvp);
178 *lvpp = NULL;
179 *uvpp = NULL;
180 return error;
181 }
182 uvp = *uvpp;
183
184 /* If we don't care about the pathname, we're done */
185 if (bufp == NULL) {
186 vput(lvp);
187 *lvpp = NULL;
188 return 0;
189 }
190
191 fileno = va.va_fileid;
192
193 dirbuflen = DIRBLKSIZ;
194 if (dirbuflen < va.va_blocksize)
195 dirbuflen = va.va_blocksize;
196 dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
197
198 #if 0
199 unionread:
200 #endif
201 off = 0;
202 do {
203 /* call VOP_READDIR of parent */
204 iov.iov_base = dirbuf;
205 iov.iov_len = dirbuflen;
206
207 uio.uio_iov = &iov;
208 uio.uio_iovcnt = 1;
209 uio.uio_offset = off;
210 uio.uio_resid = dirbuflen;
211 uio.uio_segflg = UIO_SYSSPACE;
212 uio.uio_rw = UIO_READ;
213 uio.uio_td = td;
214
215 eofflag = 0;
216
217 #ifdef MAC
218 error = mac_vnode_check_readdir(td->td_ucred, uvp);
219 if (error == 0)
220 #endif /* MAC */
221 error = VOP_READDIR(uvp, &uio, td->td_ucred, &eofflag,
222 0, 0);
223
224 off = uio.uio_offset;
225
226 /*
227 * Try again if NFS tosses its cookies.
228 * XXX this can still loop forever if the directory is busted
229 * such that the second or subsequent page of it always
230 * returns EINVAL
231 */
232 if ((error == EINVAL) && (tries < 3)) {
233 off = 0;
234 tries++;
235 continue; /* once more, with feeling */
236 }
237
238 if (!error) {
239 char *cpos;
240 struct dirent *dp;
241
242 cpos = dirbuf;
243 tries = 0;
244
245 /* scan directory page looking for matching vnode */
246 for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) {
247 dp = (struct dirent *) cpos;
248 reclen = dp->d_reclen;
249
250 /* check for malformed directory.. */
251 if (reclen < DIRENT_MINSIZE) {
252 error = EINVAL;
253 goto out;
254 }
255 /*
256 * XXX should perhaps do VOP_LOOKUP to
257 * check that we got back to the right place,
258 * but getting the locking games for that
259 * right would be heinous.
260 */
261 if ((dp->d_type != DT_WHT) &&
262 (dp->d_fileno == fileno)) {
263 char *bp = *bpp;
264 bp -= dp->d_namlen;
265
266 if (bp <= bufp) {
267 error = ERANGE;
268 goto out;
269 }
270 bcopy(dp->d_name, bp, dp->d_namlen);
271 error = 0;
272 *bpp = bp;
273 goto out;
274 }
275 cpos += reclen;
276 }
277 }
278 } while (!eofflag);
279 error = ENOENT;
280
281 out:
282 vput(lvp);
283 *lvpp = NULL;
284 free(dirbuf, M_TEMP);
285 return error;
286 }
287
288
289 /*
290 * common routine shared by sys___getcwd() and linux_vn_isunder()
291 */
292
293 #define GETCWD_CHECK_ACCESS 0x0001
294
295 static int
296 linux_getcwd_common (lvp, rvp, bpp, bufp, limit, flags, td)
297 struct vnode *lvp;
298 struct vnode *rvp;
299 char **bpp;
300 char *bufp;
301 int limit;
302 int flags;
303 struct thread *td;
304 {
305 struct filedesc *fdp = td->td_proc->p_fd;
306 struct vnode *uvp = NULL;
307 char *bp = NULL;
308 int error;
309 accmode_t accmode = VEXEC;
310
311 if (rvp == NULL) {
312 rvp = fdp->fd_rdir;
313 if (rvp == NULL)
314 rvp = rootvnode;
315 }
316
317 VREF(rvp);
318 VREF(lvp);
319
320 /*
321 * Error handling invariant:
322 * Before a `goto out':
323 * lvp is either NULL, or locked and held.
324 * uvp is either NULL, or locked and held.
325 */
326
327 error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY);
328 if (error != 0)
329 panic("vn_lock LK_RETRY returned error %d", error);
330 if (bufp)
331 bp = *bpp;
332 /*
333 * this loop will terminate when one of the following happens:
334 * - we hit the root
335 * - getdirentries or lookup fails
336 * - we run out of space in the buffer.
337 */
338 if (lvp == rvp) {
339 if (bp)
340 *(--bp) = '/';
341 goto out;
342 }
343 do {
344 if (lvp->v_type != VDIR) {
345 error = ENOTDIR;
346 goto out;
347 }
348
349 /*
350 * access check here is optional, depending on
351 * whether or not caller cares.
352 */
353 if (flags & GETCWD_CHECK_ACCESS) {
354 error = VOP_ACCESS(lvp, accmode, td->td_ucred, td);
355 if (error)
356 goto out;
357 accmode = VEXEC|VREAD;
358 }
359
360 /*
361 * step up if we're a covered vnode..
362 */
363 while (lvp->v_vflag & VV_ROOT) {
364 struct vnode *tvp;
365
366 if (lvp == rvp)
367 goto out;
368
369 tvp = lvp;
370 lvp = lvp->v_mount->mnt_vnodecovered;
371 vput(tvp);
372 /*
373 * hodie natus est radici frater
374 */
375 if (lvp == NULL) {
376 error = ENOENT;
377 goto out;
378 }
379 VREF(lvp);
380 error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY);
381 if (error != 0)
382 panic("vn_lock LK_RETRY returned %d", error);
383 }
384 error = linux_getcwd_scandir(&lvp, &uvp, &bp, bufp, td);
385 if (error)
386 goto out;
387 #ifdef DIAGNOSTIC
388 if (lvp != NULL)
389 panic("getcwd: oops, forgot to null lvp");
390 if (bufp && (bp <= bufp)) {
391 panic("getcwd: oops, went back too far");
392 }
393 #endif
394 if (bp)
395 *(--bp) = '/';
396 lvp = uvp;
397 uvp = NULL;
398 limit--;
399 } while ((lvp != rvp) && (limit > 0));
400
401 out:
402 if (bpp)
403 *bpp = bp;
404 if (uvp)
405 vput(uvp);
406 if (lvp)
407 vput(lvp);
408 vrele(rvp);
409 return error;
410 }
411
412
413 /*
414 * Find pathname of process's current directory.
415 *
416 * Use vfs vnode-to-name reverse cache; if that fails, fall back
417 * to reading directory contents.
418 */
419
420 int
421 linux_getcwd(struct thread *td, struct linux_getcwd_args *args)
422 {
423 caddr_t bp, bend, path;
424 int error, len, lenused;
425
426 #ifdef DEBUG
427 if (ldebug(getcwd))
428 printf(ARGS(getcwd, "%p, %ld"), args->buf, (long)args->bufsize);
429 #endif
430
431 len = args->bufsize;
432
433 if (len > MAXPATHLEN*4)
434 len = MAXPATHLEN*4;
435 else if (len < 2)
436 return ERANGE;
437
438 path = (char *)malloc(len, M_TEMP, M_WAITOK);
439
440 error = kern___getcwd(td, path, UIO_SYSSPACE, len);
441 if (!error) {
442 lenused = strlen(path) + 1;
443 if (lenused <= args->bufsize) {
444 td->td_retval[0] = lenused;
445 error = copyout(path, args->buf, lenused);
446 }
447 else
448 error = ERANGE;
449 } else {
450 bp = &path[len];
451 bend = bp;
452 *(--bp) = '\0';
453
454 /*
455 * 5th argument here is "max number of vnodes to traverse".
456 * Since each entry takes up at least 2 bytes in the output buffer,
457 * limit it to N/2 vnodes for an N byte buffer.
458 */
459
460 mtx_lock(&Giant);
461 error = linux_getcwd_common (td->td_proc->p_fd->fd_cdir, NULL,
462 &bp, path, len/2, GETCWD_CHECK_ACCESS, td);
463 mtx_unlock(&Giant);
464
465 if (error)
466 goto out;
467 lenused = bend - bp;
468 td->td_retval[0] = lenused;
469 /* put the result into user buffer */
470 error = copyout(bp, args->buf, lenused);
471 }
472 out:
473 free(path, M_TEMP);
474 return (error);
475 }
476
Cache object: 22a3df4f812e948b3f71e77038600ad8
|