1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software donated to Berkeley by
8 * Jan-Simon Pendry.
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. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)fdesc_vnops.c 8.9 (Berkeley) 1/21/94
35 *
36 * $FreeBSD$
37 */
38
39 /*
40 * /dev/fd Filesystem
41 */
42
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/capsicum.h>
46 #include <sys/conf.h>
47 #include <sys/dirent.h>
48 #include <sys/filedesc.h>
49 #include <sys/kernel.h> /* boottime */
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/malloc.h>
53 #include <sys/file.h> /* Must come after sys/malloc.h */
54 #include <sys/mount.h>
55 #include <sys/namei.h>
56 #include <sys/proc.h>
57 #include <sys/stat.h>
58 #include <sys/syscallsubr.h>
59 #include <sys/unistd.h>
60 #include <sys/vnode.h>
61
62 #include <fs/fdescfs/fdesc.h>
63
64 #define NFDCACHE 4
65 #define FD_NHASH(ix) \
66 (&fdhashtbl[(ix) & fdhash])
67 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl;
68 static u_long fdhash;
69
70 struct mtx fdesc_hashmtx;
71
72 static vop_getattr_t fdesc_getattr;
73 static vop_lookup_t fdesc_lookup;
74 static vop_open_t fdesc_open;
75 static vop_pathconf_t fdesc_pathconf;
76 static vop_readdir_t fdesc_readdir;
77 static vop_readlink_t fdesc_readlink;
78 static vop_reclaim_t fdesc_reclaim;
79 static vop_setattr_t fdesc_setattr;
80
81 static struct vop_vector fdesc_vnodeops = {
82 .vop_default = &default_vnodeops,
83
84 .vop_access = VOP_NULL,
85 .vop_getattr = fdesc_getattr,
86 .vop_lookup = fdesc_lookup,
87 .vop_open = fdesc_open,
88 .vop_pathconf = fdesc_pathconf,
89 .vop_readdir = fdesc_readdir,
90 .vop_readlink = fdesc_readlink,
91 .vop_reclaim = fdesc_reclaim,
92 .vop_setattr = fdesc_setattr,
93 };
94 VFS_VOP_VECTOR_REGISTER(fdesc_vnodeops);
95
96 static void fdesc_insmntque_dtr(struct vnode *, void *);
97 static void fdesc_remove_entry(struct fdescnode *);
98
99 /*
100 * Initialise cache headers
101 */
102 int
103 fdesc_init(struct vfsconf *vfsp)
104 {
105
106 mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF);
107 fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash);
108 return (0);
109 }
110
111 /*
112 * Uninit ready for unload.
113 */
114 int
115 fdesc_uninit(struct vfsconf *vfsp)
116 {
117
118 hashdestroy(fdhashtbl, M_CACHE, fdhash);
119 mtx_destroy(&fdesc_hashmtx);
120 return (0);
121 }
122
123 /*
124 * If allocating vnode fails, call this.
125 */
126 static void
127 fdesc_insmntque_dtr(struct vnode *vp, void *arg)
128 {
129
130 vgone(vp);
131 vput(vp);
132 }
133
134 /*
135 * Remove an entry from the hash if it exists.
136 */
137 static void
138 fdesc_remove_entry(struct fdescnode *fd)
139 {
140 struct fdhashhead *fc;
141 struct fdescnode *fd2;
142
143 fc = FD_NHASH(fd->fd_ix);
144 mtx_lock(&fdesc_hashmtx);
145 LIST_FOREACH(fd2, fc, fd_hash) {
146 if (fd == fd2) {
147 LIST_REMOVE(fd, fd_hash);
148 break;
149 }
150 }
151 mtx_unlock(&fdesc_hashmtx);
152 }
153
154 int
155 fdesc_allocvp(fdntype ftype, unsigned fd_fd, int ix, struct mount *mp,
156 struct vnode **vpp)
157 {
158 struct fdescmount *fmp;
159 struct fdhashhead *fc;
160 struct fdescnode *fd, *fd2;
161 struct vnode *vp, *vp2;
162 struct thread *td;
163 int error;
164
165 td = curthread;
166 fc = FD_NHASH(ix);
167 loop:
168 mtx_lock(&fdesc_hashmtx);
169 /*
170 * If a forced unmount is progressing, we need to drop it. The flags are
171 * protected by the hashmtx.
172 */
173 fmp = mp->mnt_data;
174 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
175 mtx_unlock(&fdesc_hashmtx);
176 return (-1);
177 }
178
179 LIST_FOREACH(fd, fc, fd_hash) {
180 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
181 /* Get reference to vnode in case it's being free'd */
182 vp = fd->fd_vnode;
183 VI_LOCK(vp);
184 mtx_unlock(&fdesc_hashmtx);
185 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK))
186 goto loop;
187 *vpp = vp;
188 return (0);
189 }
190 }
191 mtx_unlock(&fdesc_hashmtx);
192
193 fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK);
194
195 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp);
196 if (error) {
197 free(fd, M_TEMP);
198 return (error);
199 }
200 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
201 vp->v_data = fd;
202 fd->fd_vnode = vp;
203 fd->fd_type = ftype;
204 fd->fd_fd = fd_fd;
205 fd->fd_ix = ix;
206 if (ftype == Fdesc && fmp->flags & FMNT_LINRDLNKF)
207 vp->v_vflag |= VV_READLINK;
208 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL);
209 if (error != 0) {
210 *vpp = NULLVP;
211 return (error);
212 }
213
214 /* Make sure that someone didn't beat us when inserting the vnode. */
215 mtx_lock(&fdesc_hashmtx);
216 /*
217 * If a forced unmount is progressing, we need to drop it. The flags are
218 * protected by the hashmtx.
219 */
220 fmp = mp->mnt_data;
221 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
222 mtx_unlock(&fdesc_hashmtx);
223 vgone(vp);
224 vput(vp);
225 *vpp = NULLVP;
226 return (-1);
227 }
228
229 LIST_FOREACH(fd2, fc, fd_hash) {
230 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) {
231 /* Get reference to vnode in case it's being free'd */
232 vp2 = fd2->fd_vnode;
233 VI_LOCK(vp2);
234 mtx_unlock(&fdesc_hashmtx);
235 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK);
236 /* Someone beat us, dec use count and wait for reclaim */
237 vgone(vp);
238 vput(vp);
239 /* If we didn't get it, return no vnode. */
240 if (error)
241 vp2 = NULLVP;
242 *vpp = vp2;
243 return (error);
244 }
245 }
246
247 /* If we came here, we can insert it safely. */
248 LIST_INSERT_HEAD(fc, fd, fd_hash);
249 mtx_unlock(&fdesc_hashmtx);
250 *vpp = vp;
251 return (0);
252 }
253
254 struct fdesc_get_ino_args {
255 fdntype ftype;
256 unsigned fd_fd;
257 int ix;
258 struct file *fp;
259 struct thread *td;
260 };
261
262 static int
263 fdesc_get_ino_alloc(struct mount *mp, void *arg, int lkflags,
264 struct vnode **rvp)
265 {
266 struct fdesc_get_ino_args *a;
267 struct fdescmount *fdm;
268 struct vnode *vp;
269 int error;
270
271 a = arg;
272 fdm = VFSTOFDESC(mp);
273 if ((fdm->flags & FMNT_NODUP) != 0 && a->fp->f_type == DTYPE_VNODE) {
274 vp = a->fp->f_vnode;
275 vget(vp, lkflags | LK_RETRY);
276 *rvp = vp;
277 error = 0;
278 } else {
279 error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp);
280 }
281 fdrop(a->fp, a->td);
282 return (error);
283 }
284
285 /*
286 * vp is the current namei directory
287 * ndp is the name to locate in that directory...
288 */
289 static int
290 fdesc_lookup(struct vop_lookup_args *ap)
291 {
292 struct vnode **vpp = ap->a_vpp;
293 struct vnode *dvp = ap->a_dvp;
294 struct componentname *cnp = ap->a_cnp;
295 char *pname = cnp->cn_nameptr;
296 struct thread *td = cnp->cn_thread;
297 struct file *fp;
298 struct fdesc_get_ino_args arg;
299 int nlen = cnp->cn_namelen;
300 u_int fd, fd1;
301 int error;
302 struct vnode *fvp;
303
304 if ((cnp->cn_flags & ISLASTCN) &&
305 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
306 error = EROFS;
307 goto bad;
308 }
309
310 if (cnp->cn_namelen == 1 && *pname == '.') {
311 *vpp = dvp;
312 VREF(dvp);
313 return (0);
314 }
315
316 if (VTOFDESC(dvp)->fd_type != Froot) {
317 error = ENOTDIR;
318 goto bad;
319 }
320
321 fd = 0;
322 /* the only time a leading 0 is acceptable is if it's "" */
323 if (*pname == '' && nlen != 1) {
324 error = ENOENT;
325 goto bad;
326 }
327 while (nlen--) {
328 if (*pname < '' || *pname > '9') {
329 error = ENOENT;
330 goto bad;
331 }
332 fd1 = 10 * fd + *pname++ - '';
333 if (fd1 < fd) {
334 error = ENOENT;
335 goto bad;
336 }
337 fd = fd1;
338 }
339
340 /*
341 * No rights to check since 'fp' isn't actually used.
342 */
343 if ((error = fget(td, fd, &cap_no_rights, &fp)) != 0)
344 goto bad;
345
346 /* Check if we're looking up ourselves. */
347 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) {
348 /*
349 * In case we're holding the last reference to the file, the dvp
350 * will be re-acquired.
351 */
352 vhold(dvp);
353 VOP_UNLOCK(dvp);
354 fdrop(fp, td);
355
356 /* Re-aquire the lock afterwards. */
357 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
358 vdrop(dvp);
359 fvp = dvp;
360 if (VN_IS_DOOMED(dvp))
361 error = ENOENT;
362 } else {
363 /*
364 * Unlock our root node (dvp) when doing this, since we might
365 * deadlock since the vnode might be locked by another thread
366 * and the root vnode lock will be obtained afterwards (in case
367 * we're looking up the fd of the root vnode), which will be the
368 * opposite lock order. Vhold the root vnode first so we don't
369 * lose it.
370 */
371 arg.ftype = Fdesc;
372 arg.fd_fd = fd;
373 arg.ix = FD_DESC + fd;
374 arg.fp = fp;
375 arg.td = td;
376 error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg,
377 LK_EXCLUSIVE, &fvp);
378 }
379
380 if (error)
381 goto bad;
382 *vpp = fvp;
383 return (0);
384
385 bad:
386 *vpp = NULL;
387 return (error);
388 }
389
390 static int
391 fdesc_open(struct vop_open_args *ap)
392 {
393 struct vnode *vp = ap->a_vp;
394
395 if (VTOFDESC(vp)->fd_type == Froot)
396 return (0);
397
398 /*
399 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file
400 * descriptor being sought for duplication. The error return ensures
401 * that the vnode for this device will be released by vn_open. Open
402 * will detect this special error and take the actions in dupfdopen.
403 * Other callers of vn_open or VOP_OPEN will simply report the
404 * error.
405 */
406 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */
407 return (ENODEV);
408 }
409
410 static int
411 fdesc_pathconf(struct vop_pathconf_args *ap)
412 {
413 struct vnode *vp = ap->a_vp;
414 int error;
415
416 switch (ap->a_name) {
417 case _PC_NAME_MAX:
418 *ap->a_retval = NAME_MAX;
419 return (0);
420 case _PC_LINK_MAX:
421 if (VTOFDESC(vp)->fd_type == Froot)
422 *ap->a_retval = 2;
423 else
424 *ap->a_retval = 1;
425 return (0);
426 default:
427 if (VTOFDESC(vp)->fd_type == Froot)
428 return (vop_stdpathconf(ap));
429 vref(vp);
430 VOP_UNLOCK(vp);
431 error = kern_fpathconf(curthread, VTOFDESC(vp)->fd_fd,
432 ap->a_name, ap->a_retval);
433 vn_lock(vp, LK_SHARED | LK_RETRY);
434 vunref(vp);
435 return (error);
436 }
437 }
438
439 static int
440 fdesc_getattr(struct vop_getattr_args *ap)
441 {
442 struct vnode *vp = ap->a_vp;
443 struct vattr *vap = ap->a_vap;
444 struct timeval boottime;
445
446 getboottime(&boottime);
447 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
448 vap->va_fileid = VTOFDESC(vp)->fd_ix;
449 vap->va_uid = 0;
450 vap->va_gid = 0;
451 vap->va_blocksize = DEV_BSIZE;
452 vap->va_atime.tv_sec = boottime.tv_sec;
453 vap->va_atime.tv_nsec = 0;
454 vap->va_mtime = vap->va_atime;
455 vap->va_ctime = vap->va_mtime;
456 vap->va_gen = 0;
457 vap->va_flags = 0;
458 vap->va_bytes = 0;
459 vap->va_filerev = 0;
460
461 switch (VTOFDESC(vp)->fd_type) {
462 case Froot:
463 vap->va_type = VDIR;
464 vap->va_nlink = 2;
465 vap->va_size = DEV_BSIZE;
466 vap->va_rdev = NODEV;
467 break;
468
469 case Fdesc:
470 vap->va_type = (vp->v_vflag & VV_READLINK) == 0 ? VCHR : VLNK;
471 vap->va_nlink = 1;
472 vap->va_size = 0;
473 vap->va_rdev = makedev(0, vap->va_fileid);
474 break;
475
476 default:
477 panic("fdesc_getattr");
478 break;
479 }
480
481 vp->v_type = vap->va_type;
482 return (0);
483 }
484
485 static int
486 fdesc_setattr(struct vop_setattr_args *ap)
487 {
488 struct vattr *vap = ap->a_vap;
489 struct vnode *vp;
490 struct mount *mp;
491 struct file *fp;
492 struct thread *td = curthread;
493 cap_rights_t rights;
494 unsigned fd;
495 int error;
496
497 /*
498 * Can't mess with the root vnode
499 */
500 if (VTOFDESC(ap->a_vp)->fd_type == Froot)
501 return (EACCES);
502
503 fd = VTOFDESC(ap->a_vp)->fd_fd;
504
505 /*
506 * Allow setattr where there is an underlying vnode.
507 */
508 error = getvnode(td, fd,
509 cap_rights_init_one(&rights, CAP_EXTATTR_SET), &fp);
510 if (error) {
511 /*
512 * getvnode() returns EINVAL if the file descriptor is not
513 * backed by a vnode. Silently drop all changes except
514 * chflags(2) in this case.
515 */
516 if (error == EINVAL) {
517 if (vap->va_flags != VNOVAL)
518 error = EOPNOTSUPP;
519 else
520 error = 0;
521 }
522 return (error);
523 }
524 vp = fp->f_vnode;
525 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) {
526 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
527 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred);
528 VOP_UNLOCK(vp);
529 vn_finished_write(mp);
530 }
531 fdrop(fp, td);
532 return (error);
533 }
534
535 #define UIO_MX _GENERIC_DIRLEN(10) /* number of symbols in INT_MAX printout */
536
537 static int
538 fdesc_readdir(struct vop_readdir_args *ap)
539 {
540 struct fdescmount *fmp;
541 struct uio *uio = ap->a_uio;
542 struct filedesc *fdp;
543 struct dirent d;
544 struct dirent *dp = &d;
545 int error, i, off, fcnt;
546
547 if (VTOFDESC(ap->a_vp)->fd_type != Froot)
548 panic("fdesc_readdir: not dir");
549
550 fmp = VFSTOFDESC(ap->a_vp->v_mount);
551 if (ap->a_ncookies != NULL)
552 *ap->a_ncookies = 0;
553
554 off = (int)uio->uio_offset;
555 if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 ||
556 uio->uio_resid < UIO_MX)
557 return (EINVAL);
558 i = (u_int)off / UIO_MX;
559 fdp = uio->uio_td->td_proc->p_fd;
560 error = 0;
561
562 fcnt = i - 2; /* The first two nodes are `.' and `..' */
563
564 FILEDESC_SLOCK(fdp);
565 while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) {
566 bzero((caddr_t)dp, UIO_MX);
567 switch (i) {
568 case 0: /* `.' */
569 case 1: /* `..' */
570 dp->d_fileno = i + FD_ROOT;
571 dp->d_namlen = i + 1;
572 dp->d_reclen = UIO_MX;
573 bcopy("..", dp->d_name, dp->d_namlen);
574 dp->d_type = DT_DIR;
575 dirent_terminate(dp);
576 break;
577 default:
578 if (fdp->fd_ofiles[fcnt].fde_file == NULL)
579 break;
580 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt);
581 dp->d_reclen = UIO_MX;
582 dp->d_type = (fmp->flags & FMNT_LINRDLNKF) == 0 ?
583 DT_CHR : DT_LNK;
584 dp->d_fileno = i + FD_DESC;
585 dirent_terminate(dp);
586 break;
587 }
588 /* NOTE: d_off is the offset of the *next* entry. */
589 dp->d_off = UIO_MX * (i + 1);
590 if (dp->d_namlen != 0) {
591 /*
592 * And ship to userland
593 */
594 FILEDESC_SUNLOCK(fdp);
595 error = uiomove(dp, UIO_MX, uio);
596 if (error)
597 goto done;
598 FILEDESC_SLOCK(fdp);
599 }
600 i++;
601 fcnt++;
602 }
603 FILEDESC_SUNLOCK(fdp);
604
605 done:
606 uio->uio_offset = i * UIO_MX;
607 return (error);
608 }
609
610 static int
611 fdesc_reclaim(struct vop_reclaim_args *ap)
612 {
613 struct vnode *vp;
614 struct fdescnode *fd;
615
616 vp = ap->a_vp;
617 fd = VTOFDESC(vp);
618 fdesc_remove_entry(fd);
619 free(vp->v_data, M_TEMP);
620 vp->v_data = NULL;
621 return (0);
622 }
623
624 static int
625 fdesc_readlink(struct vop_readlink_args *va)
626 {
627 struct vnode *vp, *vn;
628 struct thread *td;
629 struct uio *uio;
630 struct file *fp;
631 char *freepath, *fullpath;
632 size_t pathlen;
633 int lockflags, fd_fd;
634 int error;
635
636 freepath = NULL;
637 vn = va->a_vp;
638 if (VTOFDESC(vn)->fd_type != Fdesc)
639 panic("fdesc_readlink: not fdescfs link");
640 fd_fd = ((struct fdescnode *)vn->v_data)->fd_fd;
641 lockflags = VOP_ISLOCKED(vn);
642 VOP_UNLOCK(vn);
643
644 td = curthread;
645 error = fget_cap(td, fd_fd, &cap_no_rights, &fp, NULL);
646 if (error != 0)
647 goto out;
648
649 switch (fp->f_type) {
650 case DTYPE_VNODE:
651 vp = fp->f_vnode;
652 error = vn_fullpath(vp, &fullpath, &freepath);
653 break;
654 default:
655 fullpath = "anon_inode:[unknown]";
656 break;
657 }
658 if (error == 0) {
659 uio = va->a_uio;
660 pathlen = strlen(fullpath);
661 error = uiomove(fullpath, pathlen, uio);
662 }
663 if (freepath != NULL)
664 free(freepath, M_TEMP);
665 fdrop(fp, td);
666
667 out:
668 vn_lock(vn, lockflags | LK_RETRY);
669 return (error);
670 }
Cache object: ecb2ca3caecd697b93a75f6bbfeaf231
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