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