Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/fdescfs/fdesc_vnops.c
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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 * 3. 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 * $FreeBSD$ 35 */ 36 37 /* 38 * /dev/fd Filesystem 39 */ 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/capsicum.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/syscallsubr.h> 57 #include <sys/unistd.h> 58 #include <sys/vnode.h> 59 60 #include <fs/fdescfs/fdesc.h> 61 62 #define NFDCACHE 4 63 #define FD_NHASH(ix) \ 64 (&fdhashtbl[(ix) & fdhash]) 65 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl; 66 static u_long fdhash; 67 68 struct mtx fdesc_hashmtx; 69 70 static vop_getattr_t fdesc_getattr; 71 static vop_lookup_t fdesc_lookup; 72 static vop_open_t fdesc_open; 73 static vop_pathconf_t fdesc_pathconf; 74 static vop_readdir_t fdesc_readdir; 75 static vop_readlink_t fdesc_readlink; 76 static vop_reclaim_t fdesc_reclaim; 77 static vop_setattr_t fdesc_setattr; 78 79 static struct vop_vector fdesc_vnodeops = { 80 .vop_default = &default_vnodeops, 81 82 .vop_access = VOP_NULL, 83 .vop_getattr = fdesc_getattr, 84 .vop_lookup = fdesc_lookup, 85 .vop_open = fdesc_open, 86 .vop_pathconf = fdesc_pathconf, 87 .vop_readdir = fdesc_readdir, 88 .vop_readlink = fdesc_readlink, 89 .vop_reclaim = fdesc_reclaim, 90 .vop_setattr = fdesc_setattr, 91 }; 92 93 static void fdesc_insmntque_dtr(struct vnode *, void *); 94 static void fdesc_remove_entry(struct fdescnode *); 95 96 /* 97 * Initialise cache headers 98 */ 99 int 100 fdesc_init(struct vfsconf *vfsp) 101 { 102 103 mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF); 104 fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash); 105 return (0); 106 } 107 108 /* 109 * Uninit ready for unload. 110 */ 111 int 112 fdesc_uninit(struct vfsconf *vfsp) 113 { 114 115 hashdestroy(fdhashtbl, M_CACHE, fdhash); 116 mtx_destroy(&fdesc_hashmtx); 117 return (0); 118 } 119 120 /* 121 * If allocating vnode fails, call this. 122 */ 123 static void 124 fdesc_insmntque_dtr(struct vnode *vp, void *arg) 125 { 126 127 vgone(vp); 128 vput(vp); 129 } 130 131 /* 132 * Remove an entry from the hash if it exists. 133 */ 134 static void 135 fdesc_remove_entry(struct fdescnode *fd) 136 { 137 struct fdhashhead *fc; 138 struct fdescnode *fd2; 139 140 fc = FD_NHASH(fd->fd_ix); 141 mtx_lock(&fdesc_hashmtx); 142 LIST_FOREACH(fd2, fc, fd_hash) { 143 if (fd == fd2) { 144 LIST_REMOVE(fd, fd_hash); 145 break; 146 } 147 } 148 mtx_unlock(&fdesc_hashmtx); 149 } 150 151 int 152 fdesc_allocvp(fdntype ftype, unsigned fd_fd, int ix, struct mount *mp, 153 struct vnode **vpp) 154 { 155 struct fdescmount *fmp; 156 struct fdhashhead *fc; 157 struct fdescnode *fd, *fd2; 158 struct vnode *vp, *vp2; 159 struct thread *td; 160 int error; 161 162 td = curthread; 163 fc = FD_NHASH(ix); 164 loop: 165 mtx_lock(&fdesc_hashmtx); 166 /* 167 * If a forced unmount is progressing, we need to drop it. The flags are 168 * protected by the hashmtx. 169 */ 170 fmp = mp->mnt_data; 171 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 172 mtx_unlock(&fdesc_hashmtx); 173 return (-1); 174 } 175 176 LIST_FOREACH(fd, fc, fd_hash) { 177 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) { 178 /* Get reference to vnode in case it's being free'd */ 179 vp = fd->fd_vnode; 180 VI_LOCK(vp); 181 mtx_unlock(&fdesc_hashmtx); 182 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td)) 183 goto loop; 184 *vpp = vp; 185 return (0); 186 } 187 } 188 mtx_unlock(&fdesc_hashmtx); 189 190 fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK); 191 192 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp); 193 if (error) { 194 free(fd, M_TEMP); 195 return (error); 196 } 197 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 198 vp->v_data = fd; 199 fd->fd_vnode = vp; 200 fd->fd_type = ftype; 201 fd->fd_fd = fd_fd; 202 fd->fd_ix = ix; 203 if (ftype == Fdesc && fmp->flags & FMNT_LINRDLNKF) 204 vp->v_vflag |= VV_READLINK; 205 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL); 206 if (error != 0) { 207 *vpp = NULLVP; 208 return (error); 209 } 210 211 /* Make sure that someone didn't beat us when inserting the vnode. */ 212 mtx_lock(&fdesc_hashmtx); 213 /* 214 * If a forced unmount is progressing, we need to drop it. The flags are 215 * protected by the hashmtx. 216 */ 217 fmp = mp->mnt_data; 218 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 219 mtx_unlock(&fdesc_hashmtx); 220 vgone(vp); 221 vput(vp); 222 *vpp = NULLVP; 223 return (-1); 224 } 225 226 LIST_FOREACH(fd2, fc, fd_hash) { 227 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) { 228 /* Get reference to vnode in case it's being free'd */ 229 vp2 = fd2->fd_vnode; 230 VI_LOCK(vp2); 231 mtx_unlock(&fdesc_hashmtx); 232 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK, td); 233 /* Someone beat us, dec use count and wait for reclaim */ 234 vgone(vp); 235 vput(vp); 236 /* If we didn't get it, return no vnode. */ 237 if (error) 238 vp2 = NULLVP; 239 *vpp = vp2; 240 return (error); 241 } 242 } 243 244 /* If we came here, we can insert it safely. */ 245 LIST_INSERT_HEAD(fc, fd, fd_hash); 246 mtx_unlock(&fdesc_hashmtx); 247 *vpp = vp; 248 return (0); 249 } 250 251 struct fdesc_get_ino_args { 252 fdntype ftype; 253 unsigned fd_fd; 254 int ix; 255 struct file *fp; 256 struct thread *td; 257 }; 258 259 static int 260 fdesc_get_ino_alloc(struct mount *mp, void *arg, int lkflags, 261 struct vnode **rvp) 262 { 263 struct fdesc_get_ino_args *a; 264 int error; 265 266 a = arg; 267 error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp); 268 fdrop(a->fp, a->td); 269 return (error); 270 } 271 272 273 /* 274 * vp is the current namei directory 275 * ndp is the name to locate in that directory... 276 */ 277 static int 278 fdesc_lookup(struct vop_lookup_args *ap) 279 { 280 struct vnode **vpp = ap->a_vpp; 281 struct vnode *dvp = ap->a_dvp; 282 struct componentname *cnp = ap->a_cnp; 283 char *pname = cnp->cn_nameptr; 284 struct thread *td = cnp->cn_thread; 285 struct file *fp; 286 struct fdesc_get_ino_args arg; 287 cap_rights_t rights; 288 int nlen = cnp->cn_namelen; 289 u_int fd, fd1; 290 int error; 291 struct vnode *fvp; 292 293 if ((cnp->cn_flags & ISLASTCN) && 294 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 295 error = EROFS; 296 goto bad; 297 } 298 299 if (cnp->cn_namelen == 1 && *pname == '.') { 300 *vpp = dvp; 301 VREF(dvp); 302 return (0); 303 } 304 305 if (VTOFDESC(dvp)->fd_type != Froot) { 306 error = ENOTDIR; 307 goto bad; 308 } 309 310 fd = 0; 311 /* the only time a leading 0 is acceptable is if it's "" */ 312 if (*pname == '' && nlen != 1) { 313 error = ENOENT; 314 goto bad; 315 } 316 while (nlen--) { 317 if (*pname < '' || *pname > '9') { 318 error = ENOENT; 319 goto bad; 320 } 321 fd1 = 10 * fd + *pname++ - ''; 322 if (fd1 < fd) { 323 error = ENOENT; 324 goto bad; 325 } 326 fd = fd1; 327 } 328 329 /* 330 * No rights to check since 'fp' isn't actually used. 331 */ 332 if ((error = fget(td, fd, cap_rights_init(&rights), &fp)) != 0) 333 goto bad; 334 335 /* Check if we're looking up ourselves. */ 336 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) { 337 /* 338 * In case we're holding the last reference to the file, the dvp 339 * will be re-acquired. 340 */ 341 vhold(dvp); 342 VOP_UNLOCK(dvp, 0); 343 fdrop(fp, td); 344 345 /* Re-aquire the lock afterwards. */ 346 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE); 347 vdrop(dvp); 348 fvp = dvp; 349 if ((dvp->v_iflag & VI_DOOMED) != 0) 350 error = ENOENT; 351 } else { 352 /* 353 * Unlock our root node (dvp) when doing this, since we might 354 * deadlock since the vnode might be locked by another thread 355 * and the root vnode lock will be obtained afterwards (in case 356 * we're looking up the fd of the root vnode), which will be the 357 * opposite lock order. Vhold the root vnode first so we don't 358 * lose it. 359 */ 360 arg.ftype = Fdesc; 361 arg.fd_fd = fd; 362 arg.ix = FD_DESC + fd; 363 arg.fp = fp; 364 arg.td = td; 365 error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg, 366 LK_EXCLUSIVE, &fvp); 367 } 368 369 if (error) 370 goto bad; 371 *vpp = fvp; 372 return (0); 373 374 bad: 375 *vpp = NULL; 376 return (error); 377 } 378 379 static int 380 fdesc_open(struct vop_open_args *ap) 381 { 382 struct vnode *vp = ap->a_vp; 383 384 if (VTOFDESC(vp)->fd_type == Froot) 385 return (0); 386 387 /* 388 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file 389 * descriptor being sought for duplication. The error return ensures 390 * that the vnode for this device will be released by vn_open. Open 391 * will detect this special error and take the actions in dupfdopen. 392 * Other callers of vn_open or VOP_OPEN will simply report the 393 * error. 394 */ 395 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */ 396 return (ENODEV); 397 } 398 399 static int 400 fdesc_pathconf(struct vop_pathconf_args *ap) 401 { 402 struct vnode *vp = ap->a_vp; 403 int error; 404 405 switch (ap->a_name) { 406 case _PC_NAME_MAX: 407 *ap->a_retval = NAME_MAX; 408 return (0); 409 case _PC_LINK_MAX: 410 if (VTOFDESC(vp)->fd_type == Froot) 411 *ap->a_retval = 2; 412 else 413 *ap->a_retval = 1; 414 return (0); 415 default: 416 if (VTOFDESC(vp)->fd_type == Froot) 417 return (vop_stdpathconf(ap)); 418 vref(vp); 419 VOP_UNLOCK(vp, 0); 420 error = kern_fpathconf(curthread, VTOFDESC(vp)->fd_fd, 421 ap->a_name); 422 vn_lock(vp, LK_SHARED | LK_RETRY); 423 vunref(vp); 424 return (error); 425 } 426 } 427 428 static int 429 fdesc_getattr(struct vop_getattr_args *ap) 430 { 431 struct vnode *vp = ap->a_vp; 432 struct vattr *vap = ap->a_vap; 433 struct timeval boottime; 434 435 getboottime(&boottime); 436 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH; 437 vap->va_fileid = VTOFDESC(vp)->fd_ix; 438 vap->va_uid = 0; 439 vap->va_gid = 0; 440 vap->va_blocksize = DEV_BSIZE; 441 vap->va_atime.tv_sec = boottime.tv_sec; 442 vap->va_atime.tv_nsec = 0; 443 vap->va_mtime = vap->va_atime; 444 vap->va_ctime = vap->va_mtime; 445 vap->va_gen = 0; 446 vap->va_flags = 0; 447 vap->va_bytes = 0; 448 vap->va_filerev = 0; 449 450 switch (VTOFDESC(vp)->fd_type) { 451 case Froot: 452 vap->va_type = VDIR; 453 vap->va_nlink = 2; 454 vap->va_size = DEV_BSIZE; 455 vap->va_rdev = NODEV; 456 break; 457 458 case Fdesc: 459 vap->va_type = (vp->v_vflag & VV_READLINK) == 0 ? VCHR : VLNK; 460 vap->va_nlink = 1; 461 vap->va_size = 0; 462 vap->va_rdev = makedev(0, vap->va_fileid); 463 break; 464 465 default: 466 panic("fdesc_getattr"); 467 break; 468 } 469 470 vp->v_type = vap->va_type; 471 return (0); 472 } 473 474 static int 475 fdesc_setattr(struct vop_setattr_args *ap) 476 { 477 struct vattr *vap = ap->a_vap; 478 struct vnode *vp; 479 struct mount *mp; 480 struct file *fp; 481 struct thread *td = curthread; 482 cap_rights_t rights; 483 unsigned fd; 484 int error; 485 486 /* 487 * Can't mess with the root vnode 488 */ 489 if (VTOFDESC(ap->a_vp)->fd_type == Froot) 490 return (EACCES); 491 492 fd = VTOFDESC(ap->a_vp)->fd_fd; 493 494 /* 495 * Allow setattr where there is an underlying vnode. 496 */ 497 error = getvnode(td, fd, 498 cap_rights_init(&rights, CAP_EXTATTR_SET), &fp); 499 if (error) { 500 /* 501 * getvnode() returns EINVAL if the file descriptor is not 502 * backed by a vnode. Silently drop all changes except 503 * chflags(2) in this case. 504 */ 505 if (error == EINVAL) { 506 if (vap->va_flags != VNOVAL) 507 error = EOPNOTSUPP; 508 else 509 error = 0; 510 } 511 return (error); 512 } 513 vp = fp->f_vnode; 514 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) { 515 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 516 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred); 517 VOP_UNLOCK(vp, 0); 518 vn_finished_write(mp); 519 } 520 fdrop(fp, td); 521 return (error); 522 } 523 524 #define UIO_MX 16 525 526 static int 527 fdesc_readdir(struct vop_readdir_args *ap) 528 { 529 struct fdescmount *fmp; 530 struct uio *uio = ap->a_uio; 531 struct filedesc *fdp; 532 struct dirent d; 533 struct dirent *dp = &d; 534 int error, i, off, fcnt; 535 536 if (VTOFDESC(ap->a_vp)->fd_type != Froot) 537 panic("fdesc_readdir: not dir"); 538 539 fmp = VFSTOFDESC(ap->a_vp->v_mount); 540 if (ap->a_ncookies != NULL) 541 *ap->a_ncookies = 0; 542 543 off = (int)uio->uio_offset; 544 if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 || 545 uio->uio_resid < UIO_MX) 546 return (EINVAL); 547 i = (u_int)off / UIO_MX; 548 fdp = uio->uio_td->td_proc->p_fd; 549 error = 0; 550 551 fcnt = i - 2; /* The first two nodes are `.' and `..' */ 552 553 FILEDESC_SLOCK(fdp); 554 while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) { 555 bzero((caddr_t)dp, UIO_MX); 556 switch (i) { 557 case 0: /* `.' */ 558 case 1: /* `..' */ 559 dp->d_fileno = i + FD_ROOT; 560 dp->d_namlen = i + 1; 561 dp->d_reclen = UIO_MX; 562 bcopy("..", dp->d_name, dp->d_namlen); 563 dp->d_type = DT_DIR; 564 dirent_terminate(dp); 565 break; 566 default: 567 if (fdp->fd_ofiles[fcnt].fde_file == NULL) 568 break; 569 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt); 570 dp->d_reclen = UIO_MX; 571 dp->d_type = (fmp->flags & FMNT_LINRDLNKF) == 0 ? 572 DT_CHR : DT_LNK; 573 dp->d_fileno = i + FD_DESC; 574 dirent_terminate(dp); 575 break; 576 } 577 if (dp->d_namlen != 0) { 578 /* 579 * And ship to userland 580 */ 581 FILEDESC_SUNLOCK(fdp); 582 error = uiomove(dp, UIO_MX, uio); 583 if (error) 584 goto done; 585 FILEDESC_SLOCK(fdp); 586 } 587 i++; 588 fcnt++; 589 } 590 FILEDESC_SUNLOCK(fdp); 591 592 done: 593 uio->uio_offset = i * UIO_MX; 594 return (error); 595 } 596 597 static int 598 fdesc_reclaim(struct vop_reclaim_args *ap) 599 { 600 struct vnode *vp; 601 struct fdescnode *fd; 602 603 vp = ap->a_vp; 604 fd = VTOFDESC(vp); 605 fdesc_remove_entry(fd); 606 free(vp->v_data, M_TEMP); 607 vp->v_data = NULL; 608 return (0); 609 } 610 611 static int 612 fdesc_readlink(struct vop_readlink_args *va) 613 { 614 struct vnode *vp, *vn; 615 cap_rights_t rights; 616 struct thread *td; 617 struct uio *uio; 618 struct file *fp; 619 char *freepath, *fullpath; 620 size_t pathlen; 621 int lockflags, fd_fd; 622 int error; 623 624 freepath = NULL; 625 vn = va->a_vp; 626 if (VTOFDESC(vn)->fd_type != Fdesc) 627 panic("fdesc_readlink: not fdescfs link"); 628 fd_fd = ((struct fdescnode *)vn->v_data)->fd_fd; 629 lockflags = VOP_ISLOCKED(vn); 630 VOP_UNLOCK(vn, 0); 631 632 td = curthread; 633 error = fget_cap(td, fd_fd, cap_rights_init(&rights), &fp, NULL); 634 if (error != 0) 635 goto out; 636 637 switch (fp->f_type) { 638 case DTYPE_VNODE: 639 vp = fp->f_vnode; 640 error = vn_fullpath(td, vp, &fullpath, &freepath); 641 break; 642 default: 643 fullpath = "anon_inode:[unknown]"; 644 break; 645 } 646 if (error == 0) { 647 uio = va->a_uio; 648 pathlen = strlen(fullpath); 649 error = uiomove(fullpath, pathlen, uio); 650 } 651 if (freepath != NULL) 652 free(freepath, M_TEMP); 653 fdrop(fp, td); 654 655 out: 656 vn_lock(vn, lockflags | LK_RETRY); 657 return (error); 658 }
Cache object: c8ec825749a4d66e7fc9965555a2d330
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