FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_vnops.c
1 /* $OpenBSD: vfs_vnops.c,v 1.121 2022/08/14 01:58:28 jsg Exp $ */
2 /* $NetBSD: vfs_vnops.c,v 1.20 1996/02/04 02:18:41 christos Exp $ */
3
4 /*
5 * Copyright (c) 1982, 1986, 1989, 1993
6 * The Regents of the University of California. All rights reserved.
7 * (c) UNIX System Laboratories, Inc.
8 * All or some portions of this file are derived from material licensed
9 * to the University of California by American Telephone and Telegraph
10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
11 * the permission of UNIX System Laboratories, Inc.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * @(#)vfs_vnops.c 8.5 (Berkeley) 12/8/94
38 */
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/malloc.h>
43 #include <sys/fcntl.h>
44 #include <sys/file.h>
45 #include <sys/stat.h>
46 #include <sys/proc.h>
47 #include <sys/resourcevar.h>
48 #include <sys/signalvar.h>
49 #include <sys/mount.h>
50 #include <sys/namei.h>
51 #include <sys/lock.h>
52 #include <sys/vnode.h>
53 #include <sys/ioctl.h>
54 #include <sys/tty.h>
55 #include <sys/specdev.h>
56 #include <sys/unistd.h>
57
58 int vn_read(struct file *, struct uio *, int);
59 int vn_write(struct file *, struct uio *, int);
60 int vn_kqfilter(struct file *, struct knote *);
61 int vn_closefile(struct file *, struct proc *);
62 int vn_seek(struct file *, off_t *, int, struct proc *);
63
64 const struct fileops vnops = {
65 .fo_read = vn_read,
66 .fo_write = vn_write,
67 .fo_ioctl = vn_ioctl,
68 .fo_kqfilter = vn_kqfilter,
69 .fo_stat = vn_statfile,
70 .fo_close = vn_closefile,
71 .fo_seek = vn_seek,
72 };
73
74 /*
75 * Common code for vnode open operations.
76 * Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
77 */
78 int
79 vn_open(struct nameidata *ndp, int fmode, int cmode)
80 {
81 struct vnode *vp;
82 struct proc *p = ndp->ni_cnd.cn_proc;
83 struct ucred *cred = p->p_ucred;
84 struct vattr va;
85 struct cloneinfo *cip;
86 int error;
87
88 /*
89 * The only valid flag to pass in here from NDINIT is
90 * KERNELPATH, This function will override the nameiop based
91 * on the fmode and cmode flags, So validate that our caller
92 * has not set other flags or operations in the nameidata
93 * structure.
94 */
95 KASSERT(ndp->ni_cnd.cn_flags == 0 || ndp->ni_cnd.cn_flags == KERNELPATH);
96 KASSERT(ndp->ni_cnd.cn_nameiop == 0);
97
98 if ((fmode & (FREAD|FWRITE)) == 0)
99 return (EINVAL);
100 if ((fmode & (O_TRUNC | FWRITE)) == O_TRUNC)
101 return (EINVAL);
102 if (fmode & O_CREAT) {
103 ndp->ni_cnd.cn_nameiop = CREATE;
104 ndp->ni_cnd.cn_flags |= LOCKPARENT | LOCKLEAF;
105 if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
106 ndp->ni_cnd.cn_flags |= FOLLOW;
107 if ((error = namei(ndp)) != 0)
108 return (error);
109
110 if (ndp->ni_vp == NULL) {
111 VATTR_NULL(&va);
112 va.va_type = VREG;
113 va.va_mode = cmode;
114 if (fmode & O_EXCL)
115 va.va_vaflags |= VA_EXCLUSIVE;
116 error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
117 &ndp->ni_cnd, &va);
118 vput(ndp->ni_dvp);
119 if (error)
120 return (error);
121 fmode &= ~O_TRUNC;
122 vp = ndp->ni_vp;
123 } else {
124 VOP_ABORTOP(ndp->ni_dvp, &ndp->ni_cnd);
125 if (ndp->ni_dvp == ndp->ni_vp)
126 vrele(ndp->ni_dvp);
127 else
128 vput(ndp->ni_dvp);
129 ndp->ni_dvp = NULL;
130 vp = ndp->ni_vp;
131 if (fmode & O_EXCL) {
132 error = EEXIST;
133 goto bad;
134 }
135 fmode &= ~O_CREAT;
136 }
137 } else {
138 ndp->ni_cnd.cn_nameiop = LOOKUP;
139 ndp->ni_cnd.cn_flags |= ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
140 if ((error = namei(ndp)) != 0)
141 return (error);
142 vp = ndp->ni_vp;
143 }
144 if (vp->v_type == VSOCK) {
145 error = EOPNOTSUPP;
146 goto bad;
147 }
148 if (vp->v_type == VLNK) {
149 error = ELOOP;
150 goto bad;
151 }
152 if ((fmode & O_DIRECTORY) && vp->v_type != VDIR) {
153 error = ENOTDIR;
154 goto bad;
155 }
156 if ((fmode & O_CREAT) == 0) {
157 if (fmode & FREAD) {
158 if ((error = VOP_ACCESS(vp, VREAD, cred, p)) != 0)
159 goto bad;
160 }
161 if (fmode & FWRITE) {
162 if (vp->v_type == VDIR) {
163 error = EISDIR;
164 goto bad;
165 }
166 if ((error = vn_writechk(vp)) != 0 ||
167 (error = VOP_ACCESS(vp, VWRITE, cred, p)) != 0)
168 goto bad;
169 }
170 }
171 if ((fmode & O_TRUNC) && vp->v_type == VREG) {
172 VATTR_NULL(&va);
173 va.va_size = 0;
174 if ((error = VOP_SETATTR(vp, &va, cred, p)) != 0)
175 goto bad;
176 }
177 if ((error = VOP_OPEN(vp, fmode, cred, p)) != 0)
178 goto bad;
179
180 if (vp->v_flag & VCLONED) {
181 cip = (struct cloneinfo *)vp->v_data;
182
183 vp->v_flag &= ~VCLONED;
184
185 ndp->ni_vp = cip->ci_vp; /* return cloned vnode */
186 vp->v_data = cip->ci_data; /* restore v_data */
187 VOP_UNLOCK(vp); /* keep a reference */
188 vp = ndp->ni_vp; /* for the increment below */
189
190 free(cip, M_TEMP, sizeof(*cip));
191 }
192
193 if (fmode & FWRITE)
194 vp->v_writecount++;
195 return (0);
196 bad:
197 vput(vp);
198 return (error);
199 }
200
201 /*
202 * Check for write permissions on the specified vnode.
203 * Prototype text segments cannot be written.
204 */
205 int
206 vn_writechk(struct vnode *vp)
207 {
208 /*
209 * Disallow write attempts on read-only file systems;
210 * unless the file is a socket or a block or character
211 * device resident on the file system.
212 */
213 if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_RDONLY)) {
214 switch (vp->v_type) {
215 case VREG:
216 case VDIR:
217 case VLNK:
218 return (EROFS);
219 case VNON:
220 case VCHR:
221 case VSOCK:
222 case VFIFO:
223 case VBAD:
224 case VBLK:
225 break;
226 }
227 }
228 /*
229 * If there's shared text associated with
230 * the vnode, try to free it up once. If
231 * we fail, we can't allow writing.
232 */
233 if ((vp->v_flag & VTEXT) && !uvm_vnp_uncache(vp))
234 return (ETXTBSY);
235
236 return (0);
237 }
238
239 /*
240 * Check whether a write operation would exceed the file size rlimit
241 * for the process, if one should be applied for this operation.
242 * If a partial write should take place, the uio is adjusted and the
243 * amount by which the request would have exceeded the limit is returned
244 * via the 'overrun' argument.
245 */
246 int
247 vn_fsizechk(struct vnode *vp, struct uio *uio, int ioflag, ssize_t *overrun)
248 {
249 struct proc *p = uio->uio_procp;
250
251 *overrun = 0;
252 if (vp->v_type == VREG && p != NULL && !(ioflag & IO_NOLIMIT)) {
253 rlim_t limit = lim_cur_proc(p, RLIMIT_FSIZE);
254
255 /* if already at or over the limit, send the signal and fail */
256 if (uio->uio_offset >= limit) {
257 psignal(p, SIGXFSZ);
258 return (EFBIG);
259 }
260
261 /* otherwise, clamp the write to stay under the limit */
262 if (uio->uio_resid > limit - uio->uio_offset) {
263 *overrun = uio->uio_resid - (limit - uio->uio_offset);
264 uio->uio_resid = limit - uio->uio_offset;
265 }
266 }
267
268 return (0);
269 }
270
271
272 /*
273 * Mark a vnode as being the text image of a running process.
274 */
275 void
276 vn_marktext(struct vnode *vp)
277 {
278 vp->v_flag |= VTEXT;
279 }
280
281 /*
282 * Vnode close call
283 */
284 int
285 vn_close(struct vnode *vp, int flags, struct ucred *cred, struct proc *p)
286 {
287 int error;
288
289 if (flags & FWRITE)
290 vp->v_writecount--;
291 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
292 error = VOP_CLOSE(vp, flags, cred, p);
293 vput(vp);
294 return (error);
295 }
296
297 /*
298 * Package up an I/O request on a vnode into a uio and do it.
299 */
300 int
301 vn_rdwr(enum uio_rw rw, struct vnode *vp, caddr_t base, int len, off_t offset,
302 enum uio_seg segflg, int ioflg, struct ucred *cred, size_t *aresid,
303 struct proc *p)
304 {
305 struct uio auio;
306 struct iovec aiov;
307 int error;
308
309 auio.uio_iov = &aiov;
310 auio.uio_iovcnt = 1;
311 aiov.iov_base = base;
312 aiov.iov_len = len;
313 auio.uio_resid = len;
314 auio.uio_offset = offset;
315 auio.uio_segflg = segflg;
316 auio.uio_rw = rw;
317 auio.uio_procp = p;
318
319 if ((ioflg & IO_NODELOCKED) == 0)
320 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
321 if (rw == UIO_READ) {
322 error = VOP_READ(vp, &auio, ioflg, cred);
323 } else {
324 error = VOP_WRITE(vp, &auio, ioflg, cred);
325 }
326 if ((ioflg & IO_NODELOCKED) == 0)
327 VOP_UNLOCK(vp);
328
329 if (aresid)
330 *aresid = auio.uio_resid;
331 else
332 if (auio.uio_resid && error == 0)
333 error = EIO;
334 return (error);
335 }
336
337 /*
338 * File table vnode read routine.
339 */
340 int
341 vn_read(struct file *fp, struct uio *uio, int fflags)
342 {
343 struct vnode *vp = fp->f_data;
344 struct ucred *cred = fp->f_cred;
345 size_t count = uio->uio_resid;
346 off_t offset;
347 int error;
348
349 KERNEL_LOCK();
350
351 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
352
353 if ((fflags & FO_POSITION) == 0)
354 offset = uio->uio_offset = fp->f_offset;
355 else
356 offset = uio->uio_offset;
357
358 /* no wrap around of offsets except on character devices */
359 if (vp->v_type != VCHR && count > LLONG_MAX - offset) {
360 error = EINVAL;
361 goto done;
362 }
363
364 if (vp->v_type == VDIR) {
365 error = EISDIR;
366 goto done;
367 }
368
369 error = VOP_READ(vp, uio, (fp->f_flag & FNONBLOCK) ? IO_NDELAY : 0,
370 cred);
371 if ((fflags & FO_POSITION) == 0) {
372 mtx_enter(&fp->f_mtx);
373 fp->f_offset += count - uio->uio_resid;
374 mtx_leave(&fp->f_mtx);
375 }
376 done:
377 VOP_UNLOCK(vp);
378 KERNEL_UNLOCK();
379 return (error);
380 }
381
382 /*
383 * File table vnode write routine.
384 */
385 int
386 vn_write(struct file *fp, struct uio *uio, int fflags)
387 {
388 struct vnode *vp = fp->f_data;
389 struct ucred *cred = fp->f_cred;
390 int error, ioflag = IO_UNIT;
391 size_t count;
392
393 KERNEL_LOCK();
394
395 /* note: pwrite/pwritev are unaffected by O_APPEND */
396 if (vp->v_type == VREG && (fp->f_flag & O_APPEND) &&
397 (fflags & FO_POSITION) == 0)
398 ioflag |= IO_APPEND;
399 if (fp->f_flag & FNONBLOCK)
400 ioflag |= IO_NDELAY;
401 if ((fp->f_flag & FFSYNC) ||
402 (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
403 ioflag |= IO_SYNC;
404 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
405 if ((fflags & FO_POSITION) == 0)
406 uio->uio_offset = fp->f_offset;
407 count = uio->uio_resid;
408 error = VOP_WRITE(vp, uio, ioflag, cred);
409 if ((fflags & FO_POSITION) == 0) {
410 mtx_enter(&fp->f_mtx);
411 if (ioflag & IO_APPEND)
412 fp->f_offset = uio->uio_offset;
413 else
414 fp->f_offset += count - uio->uio_resid;
415 mtx_leave(&fp->f_mtx);
416 }
417 VOP_UNLOCK(vp);
418
419 KERNEL_UNLOCK();
420 return (error);
421 }
422
423 /*
424 * File table wrapper for vn_stat
425 */
426 int
427 vn_statfile(struct file *fp, struct stat *sb, struct proc *p)
428 {
429 struct vnode *vp = fp->f_data;
430 return vn_stat(vp, sb, p);
431 }
432
433 /*
434 * vnode stat routine.
435 */
436 int
437 vn_stat(struct vnode *vp, struct stat *sb, struct proc *p)
438 {
439 struct vattr va;
440 int error;
441 mode_t mode;
442
443 error = VOP_GETATTR(vp, &va, p->p_ucred, p);
444 if (error)
445 return (error);
446 /*
447 * Copy from vattr table
448 */
449 memset(sb, 0, sizeof(*sb));
450 sb->st_dev = va.va_fsid;
451 sb->st_ino = va.va_fileid;
452 mode = va.va_mode;
453 switch (vp->v_type) {
454 case VREG:
455 mode |= S_IFREG;
456 break;
457 case VDIR:
458 mode |= S_IFDIR;
459 break;
460 case VBLK:
461 mode |= S_IFBLK;
462 break;
463 case VCHR:
464 mode |= S_IFCHR;
465 break;
466 case VLNK:
467 mode |= S_IFLNK;
468 break;
469 case VSOCK:
470 mode |= S_IFSOCK;
471 break;
472 case VFIFO:
473 mode |= S_IFIFO;
474 break;
475 default:
476 return (EBADF);
477 }
478 sb->st_mode = mode;
479 sb->st_nlink = va.va_nlink;
480 sb->st_uid = va.va_uid;
481 sb->st_gid = va.va_gid;
482 sb->st_rdev = va.va_rdev;
483 sb->st_size = va.va_size;
484 sb->st_atim.tv_sec = va.va_atime.tv_sec;
485 sb->st_atim.tv_nsec = va.va_atime.tv_nsec;
486 sb->st_mtim.tv_sec = va.va_mtime.tv_sec;
487 sb->st_mtim.tv_nsec = va.va_mtime.tv_nsec;
488 sb->st_ctim.tv_sec = va.va_ctime.tv_sec;
489 sb->st_ctim.tv_nsec = va.va_ctime.tv_nsec;
490 sb->st_blksize = va.va_blocksize;
491 sb->st_flags = va.va_flags;
492 sb->st_gen = va.va_gen;
493 sb->st_blocks = va.va_bytes / S_BLKSIZE;
494 return (0);
495 }
496
497 /*
498 * File table vnode ioctl routine.
499 */
500 int
501 vn_ioctl(struct file *fp, u_long com, caddr_t data, struct proc *p)
502 {
503 struct vnode *vp = fp->f_data;
504 struct vattr vattr;
505 int error = ENOTTY;
506
507 KERNEL_LOCK();
508 switch (vp->v_type) {
509
510 case VREG:
511 case VDIR:
512 if (com == FIONREAD) {
513 error = VOP_GETATTR(vp, &vattr, p->p_ucred, p);
514 if (error)
515 break;
516 *(int *)data = vattr.va_size - foffset(fp);
517
518 } else if (com == FIONBIO || com == FIOASYNC) /* XXX */
519 error = 0; /* XXX */
520 break;
521
522 case VFIFO:
523 case VCHR:
524 case VBLK:
525 error = VOP_IOCTL(vp, com, data, fp->f_flag, p->p_ucred, p);
526 if (error == 0 && com == TIOCSCTTY) {
527 struct session *s = p->p_p->ps_session;
528 struct vnode *ovp = s->s_ttyvp;
529 s->s_ttyvp = vp;
530 vref(vp);
531 if (ovp)
532 vrele(ovp);
533 }
534 break;
535
536 default:
537 break;
538 }
539 KERNEL_UNLOCK();
540
541 return (error);
542 }
543
544 /*
545 * Check that the vnode is still valid, and if so
546 * acquire requested lock.
547 */
548 int
549 vn_lock(struct vnode *vp, int flags)
550 {
551 int error, xlocked, do_wakeup;
552
553 do {
554 mtx_enter(&vnode_mtx);
555 if (vp->v_lflag & VXLOCK) {
556 vp->v_lflag |= VXWANT;
557 msleep_nsec(vp, &vnode_mtx, PINOD, "vn_lock", INFSLP);
558 mtx_leave(&vnode_mtx);
559 error = ENOENT;
560 } else {
561 vp->v_lockcount++;
562 mtx_leave(&vnode_mtx);
563
564 error = VOP_LOCK(vp, flags);
565
566 mtx_enter(&vnode_mtx);
567 vp->v_lockcount--;
568 do_wakeup = (vp->v_lockcount == 0);
569 xlocked = vp->v_lflag & VXLOCK;
570 mtx_leave(&vnode_mtx);
571
572 if (error == 0) {
573 if (!xlocked)
574 return (0);
575
576 /*
577 * The vnode was exclusively locked while
578 * acquiring the requested lock. Release it and
579 * try again.
580 */
581 error = ENOENT;
582 VOP_UNLOCK(vp);
583 if (do_wakeup)
584 wakeup_one(&vp->v_lockcount);
585 }
586 }
587 } while (flags & LK_RETRY);
588 return (error);
589 }
590
591 /*
592 * File table vnode close routine.
593 */
594 int
595 vn_closefile(struct file *fp, struct proc *p)
596 {
597 struct vnode *vp = fp->f_data;
598 struct flock lf;
599 int error;
600
601 KERNEL_LOCK();
602 if ((fp->f_iflags & FIF_HASLOCK)) {
603 lf.l_whence = SEEK_SET;
604 lf.l_start = 0;
605 lf.l_len = 0;
606 lf.l_type = F_UNLCK;
607 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
608 }
609 error = vn_close(vp, fp->f_flag, fp->f_cred, p);
610 KERNEL_UNLOCK();
611 return (error);
612 }
613
614 int
615 vn_kqfilter(struct file *fp, struct knote *kn)
616 {
617 int error;
618
619 KERNEL_LOCK();
620 error = VOP_KQFILTER(fp->f_data, fp->f_flag, kn);
621 KERNEL_UNLOCK();
622 return (error);
623 }
624
625 int
626 vn_seek(struct file *fp, off_t *offset, int whence, struct proc *p)
627 {
628 struct ucred *cred = p->p_ucred;
629 struct vnode *vp = fp->f_data;
630 struct vattr vattr;
631 off_t newoff;
632 int error = 0;
633 int special;
634
635 if (vp->v_type == VFIFO)
636 return (ESPIPE);
637
638 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
639
640 if (vp->v_type == VCHR)
641 special = 1;
642 else
643 special = 0;
644
645 switch (whence) {
646 case SEEK_CUR:
647 newoff = fp->f_offset + *offset;
648 break;
649 case SEEK_END:
650 KERNEL_LOCK();
651 error = VOP_GETATTR(vp, &vattr, cred, p);
652 KERNEL_UNLOCK();
653 if (error)
654 goto out;
655 newoff = *offset + (off_t)vattr.va_size;
656 break;
657 case SEEK_SET:
658 newoff = *offset;
659 break;
660 default:
661 error = EINVAL;
662 goto out;
663 }
664 if (!special && newoff < 0) {
665 error = EINVAL;
666 goto out;
667 }
668 mtx_enter(&fp->f_mtx);
669 fp->f_offset = newoff;
670 mtx_leave(&fp->f_mtx);
671 *offset = newoff;
672
673 out:
674 VOP_UNLOCK(vp);
675 return (error);
676 }
677
678 /*
679 * Common code for vnode access operations.
680 */
681
682 /* Check if a directory can be found inside another in the hierarchy */
683 int
684 vn_isunder(struct vnode *lvp, struct vnode *rvp, struct proc *p)
685 {
686 int error;
687
688 error = vfs_getcwd_common(lvp, rvp, NULL, NULL, MAXPATHLEN/2, 0, p);
689
690 if (!error)
691 return (1);
692
693 return (0);
694 }
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