1 /*-
2 * Copyright (c) 1992, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software donated to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)fdesc_vnops.c 8.9 (Berkeley) 1/21/94
33 *
34 * $FreeBSD: releng/10.0/sys/fs/fdescfs/fdesc_vnops.c 255240 2013-09-05 11:58:12Z pjd $
35 */
36
37 /*
38 * /dev/fd Filesystem
39 */
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/capability.h>
44 #include <sys/conf.h>
45 #include <sys/dirent.h>
46 #include <sys/filedesc.h>
47 #include <sys/kernel.h> /* boottime */
48 #include <sys/lock.h>
49 #include <sys/mutex.h>
50 #include <sys/malloc.h>
51 #include <sys/file.h> /* Must come after sys/malloc.h */
52 #include <sys/mount.h>
53 #include <sys/namei.h>
54 #include <sys/proc.h>
55 #include <sys/stat.h>
56 #include <sys/vnode.h>
57
58 #include <fs/fdescfs/fdesc.h>
59
60 #define NFDCACHE 4
61 #define FD_NHASH(ix) \
62 (&fdhashtbl[(ix) & fdhash])
63 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl;
64 static u_long fdhash;
65
66 struct mtx fdesc_hashmtx;
67
68 static vop_getattr_t fdesc_getattr;
69 static vop_lookup_t fdesc_lookup;
70 static vop_open_t fdesc_open;
71 static vop_readdir_t fdesc_readdir;
72 static vop_reclaim_t fdesc_reclaim;
73 static vop_setattr_t fdesc_setattr;
74
75 static struct vop_vector fdesc_vnodeops = {
76 .vop_default = &default_vnodeops,
77
78 .vop_access = VOP_NULL,
79 .vop_getattr = fdesc_getattr,
80 .vop_lookup = fdesc_lookup,
81 .vop_open = fdesc_open,
82 .vop_pathconf = vop_stdpathconf,
83 .vop_readdir = fdesc_readdir,
84 .vop_reclaim = fdesc_reclaim,
85 .vop_setattr = fdesc_setattr,
86 };
87
88 static void fdesc_insmntque_dtr(struct vnode *, void *);
89 static void fdesc_remove_entry(struct fdescnode *);
90
91 /*
92 * Initialise cache headers
93 */
94 int
95 fdesc_init(vfsp)
96 struct vfsconf *vfsp;
97 {
98
99 mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF);
100 fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash);
101 return (0);
102 }
103
104 /*
105 * Uninit ready for unload.
106 */
107 int
108 fdesc_uninit(vfsp)
109 struct vfsconf *vfsp;
110 {
111
112 hashdestroy(fdhashtbl, M_CACHE, fdhash);
113 mtx_destroy(&fdesc_hashmtx);
114 return (0);
115 }
116
117 /*
118 * If allocating vnode fails, call this.
119 */
120 static void
121 fdesc_insmntque_dtr(struct vnode *vp, void *arg)
122 {
123
124 vgone(vp);
125 vput(vp);
126 }
127
128 /*
129 * Remove an entry from the hash if it exists.
130 */
131 static void
132 fdesc_remove_entry(struct fdescnode *fd)
133 {
134 struct fdhashhead *fc;
135 struct fdescnode *fd2;
136
137 fc = FD_NHASH(fd->fd_ix);
138 mtx_lock(&fdesc_hashmtx);
139 LIST_FOREACH(fd2, fc, fd_hash) {
140 if (fd == fd2) {
141 LIST_REMOVE(fd, fd_hash);
142 break;
143 }
144 }
145 mtx_unlock(&fdesc_hashmtx);
146 }
147
148 int
149 fdesc_allocvp(ftype, fd_fd, ix, mp, vpp)
150 fdntype ftype;
151 unsigned fd_fd;
152 int ix;
153 struct mount *mp;
154 struct vnode **vpp;
155 {
156 struct fdescmount *fmp;
157 struct fdhashhead *fc;
158 struct fdescnode *fd, *fd2;
159 struct vnode *vp, *vp2;
160 struct thread *td;
161 int error = 0;
162
163 td = curthread;
164 fc = FD_NHASH(ix);
165 loop:
166 mtx_lock(&fdesc_hashmtx);
167 /*
168 * If a forced unmount is progressing, we need to drop it. The flags are
169 * protected by the hashmtx.
170 */
171 fmp = (struct fdescmount *)mp->mnt_data;
172 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
173 mtx_unlock(&fdesc_hashmtx);
174 return (-1);
175 }
176
177 LIST_FOREACH(fd, fc, fd_hash) {
178 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
179 /* Get reference to vnode in case it's being free'd */
180 vp = fd->fd_vnode;
181 VI_LOCK(vp);
182 mtx_unlock(&fdesc_hashmtx);
183 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td))
184 goto loop;
185 *vpp = vp;
186 return (0);
187 }
188 }
189 mtx_unlock(&fdesc_hashmtx);
190
191 fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK);
192
193 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp);
194 if (error) {
195 free(fd, M_TEMP);
196 return (error);
197 }
198 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
199 vp->v_data = fd;
200 fd->fd_vnode = vp;
201 fd->fd_type = ftype;
202 fd->fd_fd = fd_fd;
203 fd->fd_ix = ix;
204 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL);
205 if (error != 0) {
206 *vpp = NULLVP;
207 return (error);
208 }
209
210 /* Make sure that someone didn't beat us when inserting the vnode. */
211 mtx_lock(&fdesc_hashmtx);
212 /*
213 * If a forced unmount is progressing, we need to drop it. The flags are
214 * protected by the hashmtx.
215 */
216 fmp = (struct fdescmount *)mp->mnt_data;
217 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
218 mtx_unlock(&fdesc_hashmtx);
219 vgone(vp);
220 vput(vp);
221 *vpp = NULLVP;
222 return (-1);
223 }
224
225 LIST_FOREACH(fd2, fc, fd_hash) {
226 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) {
227 /* Get reference to vnode in case it's being free'd */
228 vp2 = fd2->fd_vnode;
229 VI_LOCK(vp2);
230 mtx_unlock(&fdesc_hashmtx);
231 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK, td);
232 /* Someone beat us, dec use count and wait for reclaim */
233 vgone(vp);
234 vput(vp);
235 /* If we didn't get it, return no vnode. */
236 if (error)
237 vp2 = NULLVP;
238 *vpp = vp2;
239 return (error);
240 }
241 }
242
243 /* If we came here, we can insert it safely. */
244 LIST_INSERT_HEAD(fc, fd, fd_hash);
245 mtx_unlock(&fdesc_hashmtx);
246 *vpp = vp;
247 return (0);
248 }
249
250 /*
251 * vp is the current namei directory
252 * ndp is the name to locate in that directory...
253 */
254 static int
255 fdesc_lookup(ap)
256 struct vop_lookup_args /* {
257 struct vnode * a_dvp;
258 struct vnode ** a_vpp;
259 struct componentname * a_cnp;
260 } */ *ap;
261 {
262 struct vnode **vpp = ap->a_vpp;
263 struct vnode *dvp = ap->a_dvp;
264 struct componentname *cnp = ap->a_cnp;
265 char *pname = cnp->cn_nameptr;
266 struct thread *td = cnp->cn_thread;
267 struct file *fp;
268 int nlen = cnp->cn_namelen;
269 u_int fd, fd1;
270 int error;
271 struct vnode *fvp;
272
273 if ((cnp->cn_flags & ISLASTCN) &&
274 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
275 error = EROFS;
276 goto bad;
277 }
278
279 if (cnp->cn_namelen == 1 && *pname == '.') {
280 *vpp = dvp;
281 VREF(dvp);
282 return (0);
283 }
284
285 if (VTOFDESC(dvp)->fd_type != Froot) {
286 error = ENOTDIR;
287 goto bad;
288 }
289
290 fd = 0;
291 /* the only time a leading 0 is acceptable is if it's "" */
292 if (*pname == '' && nlen != 1) {
293 error = ENOENT;
294 goto bad;
295 }
296 while (nlen--) {
297 if (*pname < '' || *pname > '9') {
298 error = ENOENT;
299 goto bad;
300 }
301 fd1 = 10 * fd + *pname++ - '';
302 if (fd1 < fd) {
303 error = ENOENT;
304 goto bad;
305 }
306 fd = fd1;
307 }
308
309 /*
310 * No rights to check since 'fp' isn't actually used.
311 */
312 if ((error = fget(td, fd, NULL, &fp)) != 0)
313 goto bad;
314
315 /* Check if we're looking up ourselves. */
316 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) {
317 /*
318 * In case we're holding the last reference to the file, the dvp
319 * will be re-acquired.
320 */
321 vhold(dvp);
322 VOP_UNLOCK(dvp, 0);
323 fdrop(fp, td);
324
325 /* Re-aquire the lock afterwards. */
326 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
327 vdrop(dvp);
328 fvp = dvp;
329 } else {
330 /*
331 * Unlock our root node (dvp) when doing this, since we might
332 * deadlock since the vnode might be locked by another thread
333 * and the root vnode lock will be obtained afterwards (in case
334 * we're looking up the fd of the root vnode), which will be the
335 * opposite lock order. Vhold the root vnode first so we don't
336 * lose it.
337 */
338 vhold(dvp);
339 VOP_UNLOCK(dvp, 0);
340 error = fdesc_allocvp(Fdesc, fd, FD_DESC + fd, dvp->v_mount,
341 &fvp);
342 fdrop(fp, td);
343 /*
344 * The root vnode must be locked last to prevent deadlock condition.
345 */
346 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
347 vdrop(dvp);
348 }
349
350 if (error)
351 goto bad;
352 *vpp = fvp;
353 return (0);
354
355 bad:
356 *vpp = NULL;
357 return (error);
358 }
359
360 static int
361 fdesc_open(ap)
362 struct vop_open_args /* {
363 struct vnode *a_vp;
364 int a_mode;
365 struct ucred *a_cred;
366 struct thread *a_td;
367 } */ *ap;
368 {
369 struct vnode *vp = ap->a_vp;
370
371 if (VTOFDESC(vp)->fd_type == Froot)
372 return (0);
373
374 /*
375 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file
376 * descriptor being sought for duplication. The error return ensures
377 * that the vnode for this device will be released by vn_open. Open
378 * will detect this special error and take the actions in dupfdopen.
379 * Other callers of vn_open or VOP_OPEN will simply report the
380 * error.
381 */
382 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */
383 return (ENODEV);
384 }
385
386 static int
387 fdesc_getattr(ap)
388 struct vop_getattr_args /* {
389 struct vnode *a_vp;
390 struct vattr *a_vap;
391 struct ucred *a_cred;
392 } */ *ap;
393 {
394 struct vnode *vp = ap->a_vp;
395 struct vattr *vap = ap->a_vap;
396
397 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
398 vap->va_fileid = VTOFDESC(vp)->fd_ix;
399 vap->va_uid = 0;
400 vap->va_gid = 0;
401 vap->va_blocksize = DEV_BSIZE;
402 vap->va_atime.tv_sec = boottime.tv_sec;
403 vap->va_atime.tv_nsec = 0;
404 vap->va_mtime = vap->va_atime;
405 vap->va_ctime = vap->va_mtime;
406 vap->va_gen = 0;
407 vap->va_flags = 0;
408 vap->va_bytes = 0;
409 vap->va_filerev = 0;
410
411 switch (VTOFDESC(vp)->fd_type) {
412 case Froot:
413 vap->va_type = VDIR;
414 vap->va_nlink = 2;
415 vap->va_size = DEV_BSIZE;
416 vap->va_rdev = NODEV;
417 break;
418
419 case Fdesc:
420 vap->va_type = VCHR;
421 vap->va_nlink = 1;
422 vap->va_size = 0;
423 vap->va_rdev = makedev(0, vap->va_fileid);
424 break;
425
426 default:
427 panic("fdesc_getattr");
428 break;
429 }
430
431 vp->v_type = vap->va_type;
432 return (0);
433 }
434
435 static int
436 fdesc_setattr(ap)
437 struct vop_setattr_args /* {
438 struct vnode *a_vp;
439 struct vattr *a_vap;
440 struct ucred *a_cred;
441 } */ *ap;
442 {
443 struct vattr *vap = ap->a_vap;
444 struct vnode *vp;
445 struct mount *mp;
446 struct file *fp;
447 struct thread *td = curthread;
448 cap_rights_t rights;
449 unsigned fd;
450 int error;
451
452 /*
453 * Can't mess with the root vnode
454 */
455 if (VTOFDESC(ap->a_vp)->fd_type == Froot)
456 return (EACCES);
457
458 fd = VTOFDESC(ap->a_vp)->fd_fd;
459
460 /*
461 * Allow setattr where there is an underlying vnode.
462 */
463 error = getvnode(td->td_proc->p_fd, fd,
464 cap_rights_init(&rights, CAP_EXTATTR_SET), &fp);
465 if (error) {
466 /*
467 * getvnode() returns EINVAL if the file descriptor is not
468 * backed by a vnode. Silently drop all changes except
469 * chflags(2) in this case.
470 */
471 if (error == EINVAL) {
472 if (vap->va_flags != VNOVAL)
473 error = EOPNOTSUPP;
474 else
475 error = 0;
476 }
477 return (error);
478 }
479 vp = fp->f_vnode;
480 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) {
481 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
482 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred);
483 VOP_UNLOCK(vp, 0);
484 vn_finished_write(mp);
485 }
486 fdrop(fp, td);
487 return (error);
488 }
489
490 #define UIO_MX 16
491
492 static int
493 fdesc_readdir(ap)
494 struct vop_readdir_args /* {
495 struct vnode *a_vp;
496 struct uio *a_uio;
497 struct ucred *a_cred;
498 int *a_eofflag;
499 u_long *a_cookies;
500 int a_ncookies;
501 } */ *ap;
502 {
503 struct uio *uio = ap->a_uio;
504 struct filedesc *fdp;
505 struct dirent d;
506 struct dirent *dp = &d;
507 int error, i, off, fcnt;
508
509 if (VTOFDESC(ap->a_vp)->fd_type != Froot)
510 panic("fdesc_readdir: not dir");
511
512 if (ap->a_ncookies != NULL)
513 *ap->a_ncookies = 0;
514
515 off = (int)uio->uio_offset;
516 if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 ||
517 uio->uio_resid < UIO_MX)
518 return (EINVAL);
519 i = (u_int)off / UIO_MX;
520 fdp = uio->uio_td->td_proc->p_fd;
521 error = 0;
522
523 fcnt = i - 2; /* The first two nodes are `.' and `..' */
524
525 FILEDESC_SLOCK(fdp);
526 while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) {
527 bzero((caddr_t)dp, UIO_MX);
528 switch (i) {
529 case 0: /* `.' */
530 case 1: /* `..' */
531 dp->d_fileno = i + FD_ROOT;
532 dp->d_namlen = i + 1;
533 dp->d_reclen = UIO_MX;
534 bcopy("..", dp->d_name, dp->d_namlen);
535 dp->d_name[i + 1] = '\0';
536 dp->d_type = DT_DIR;
537 break;
538 default:
539 if (fdp->fd_ofiles[fcnt].fde_file == NULL)
540 break;
541 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt);
542 dp->d_reclen = UIO_MX;
543 dp->d_type = DT_CHR;
544 dp->d_fileno = i + FD_DESC;
545 break;
546 }
547 if (dp->d_namlen != 0) {
548 /*
549 * And ship to userland
550 */
551 FILEDESC_SUNLOCK(fdp);
552 error = uiomove(dp, UIO_MX, uio);
553 if (error)
554 goto done;
555 FILEDESC_SLOCK(fdp);
556 }
557 i++;
558 fcnt++;
559 }
560 FILEDESC_SUNLOCK(fdp);
561
562 done:
563 uio->uio_offset = i * UIO_MX;
564 return (error);
565 }
566
567 static int
568 fdesc_reclaim(ap)
569 struct vop_reclaim_args /* {
570 struct vnode *a_vp;
571 } */ *ap;
572 {
573 struct vnode *vp;
574 struct fdescnode *fd;
575
576 vp = ap->a_vp;
577 fd = VTOFDESC(vp);
578 fdesc_remove_entry(fd);
579 free(vp->v_data, M_TEMP);
580 vp->v_data = NULL;
581 return (0);
582 }
Cache object: 1cea99b1e7f3699b07b11ecd82e48ea5
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