1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2014 The FreeBSD Foundation 5 * 6 * This software was developed by Edward Tomasz Napierala under sponsorship 7 * from the FreeBSD Foundation. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/condvar.h> 39 #include <sys/dirent.h> 40 #include <sys/fcntl.h> 41 #include <sys/lock.h> 42 #include <sys/mount.h> 43 #include <sys/mutex.h> 44 #include <sys/namei.h> 45 #include <sys/signalvar.h> 46 #include <sys/stat.h> 47 #include <sys/taskqueue.h> 48 #include <sys/tree.h> 49 #include <sys/vnode.h> 50 #include <machine/atomic.h> 51 #include <vm/uma.h> 52 53 #include <fs/autofs/autofs.h> 54 55 static int autofs_trigger_vn(struct vnode *vp, const char *path, 56 int pathlen, struct vnode **newvp); 57 58 extern struct autofs_softc *autofs_softc; 59 60 static int 61 autofs_access(struct vop_access_args *ap) 62 { 63 64 /* 65 * Nothing to do here; the only kind of access control 66 * needed is in autofs_mkdir(). 67 */ 68 69 return (0); 70 } 71 72 static int 73 autofs_getattr(struct vop_getattr_args *ap) 74 { 75 struct vnode *vp, *newvp; 76 struct autofs_node *anp; 77 struct mount *mp; 78 struct vattr *vap; 79 int error; 80 81 vp = ap->a_vp; 82 anp = vp->v_data; 83 mp = vp->v_mount; 84 vap = ap->a_vap; 85 86 KASSERT(ap->a_vp->v_type == VDIR, ("!VDIR")); 87 88 /* 89 * The reason we must do this is that some tree-walking software, 90 * namely fts(3), assumes that stat(".") results will not change 91 * between chdir("subdir") and chdir(".."), and fails with ENOENT 92 * otherwise. 93 */ 94 if (autofs_mount_on_stat && autofs_cached(anp, NULL, 0) == false && 95 autofs_ignore_thread(curthread) == false) { 96 error = autofs_trigger_vn(vp, "", 0, &newvp); 97 if (error != 0) 98 return (error); 99 100 if (newvp != NULL) { 101 error = VOP_GETATTR(newvp, ap->a_vap, 102 ap->a_cred); 103 vput(newvp); 104 return (error); 105 } 106 } 107 108 vap->va_type = VDIR; 109 vap->va_mode = 0755; 110 vap->va_nlink = 3; /* XXX */ 111 vap->va_uid = 0; 112 vap->va_gid = 0; 113 vap->va_rdev = NODEV; 114 vap->va_fsid = mp->mnt_stat.f_fsid.val[0]; 115 vap->va_fileid = anp->an_fileno; 116 vap->va_size = S_BLKSIZE; 117 vap->va_blocksize = S_BLKSIZE; 118 vap->va_mtime = anp->an_ctime; 119 vap->va_atime = anp->an_ctime; 120 vap->va_ctime = anp->an_ctime; 121 vap->va_birthtime = anp->an_ctime; 122 vap->va_gen = 0; 123 vap->va_flags = 0; 124 vap->va_rdev = 0; 125 vap->va_bytes = S_BLKSIZE; 126 vap->va_filerev = 0; 127 vap->va_spare = 0; 128 129 return (0); 130 } 131 132 /* 133 * Unlock the vnode, request automountd(8) action, and then lock it back. 134 * If anything got mounted on top of the vnode, return the new filesystem's 135 * root vnode in 'newvp', locked. 136 */ 137 static int 138 autofs_trigger_vn(struct vnode *vp, const char *path, int pathlen, 139 struct vnode **newvp) 140 { 141 struct autofs_node *anp; 142 int error, lock_flags; 143 144 anp = vp->v_data; 145 146 /* 147 * Release the vnode lock, so that other operations, in partcular 148 * mounting a filesystem on top of it, can proceed. Increase use 149 * count, to prevent the vnode from being deallocated and to prevent 150 * filesystem from being unmounted. 151 */ 152 lock_flags = VOP_ISLOCKED(vp); 153 vref(vp); 154 VOP_UNLOCK(vp); 155 156 sx_xlock(&autofs_softc->sc_lock); 157 158 /* 159 * XXX: Workaround for mounting the same thing multiple times; revisit. 160 */ 161 if (vp->v_mountedhere != NULL) { 162 error = 0; 163 goto mounted; 164 } 165 166 error = autofs_trigger(anp, path, pathlen); 167 mounted: 168 sx_xunlock(&autofs_softc->sc_lock); 169 vn_lock(vp, lock_flags | LK_RETRY); 170 vunref(vp); 171 if (VN_IS_DOOMED(vp)) { 172 AUTOFS_DEBUG("VIRF_DOOMED"); 173 return (ENOENT); 174 } 175 176 if (error != 0) 177 return (error); 178 179 if (vp->v_mountedhere == NULL) { 180 *newvp = NULL; 181 return (0); 182 } else { 183 /* 184 * If the operation that succeeded was mount, then mark 185 * the node as non-cached. Otherwise, if someone unmounts 186 * the filesystem before the cache times out, we will fail 187 * to trigger. 188 */ 189 anp->an_cached = false; 190 } 191 192 error = VFS_ROOT(vp->v_mountedhere, lock_flags, newvp); 193 if (error != 0) { 194 AUTOFS_WARN("VFS_ROOT() failed with error %d", error); 195 return (error); 196 } 197 198 return (0); 199 } 200 201 static int 202 autofs_vget_callback(struct mount *mp, void *arg, int flags, 203 struct vnode **vpp) 204 { 205 206 return (autofs_node_vn(arg, mp, flags, vpp)); 207 } 208 209 static int 210 autofs_lookup(struct vop_lookup_args *ap) 211 { 212 struct vnode *dvp, *newvp, **vpp; 213 struct mount *mp; 214 struct autofs_mount *amp; 215 struct autofs_node *anp, *child; 216 struct componentname *cnp; 217 int error; 218 219 dvp = ap->a_dvp; 220 vpp = ap->a_vpp; 221 mp = dvp->v_mount; 222 amp = VFSTOAUTOFS(mp); 223 anp = dvp->v_data; 224 cnp = ap->a_cnp; 225 226 if (cnp->cn_flags & ISDOTDOT) { 227 KASSERT(anp->an_parent != NULL, ("NULL parent")); 228 /* 229 * Note that in this case, dvp is the child vnode, and we 230 * are looking up the parent vnode - exactly reverse from 231 * normal operation. Unlocking dvp requires some rather 232 * tricky unlock/relock dance to prevent mp from being freed; 233 * use vn_vget_ino_gen() which takes care of all that. 234 */ 235 error = vn_vget_ino_gen(dvp, autofs_vget_callback, 236 anp->an_parent, cnp->cn_lkflags, vpp); 237 if (error != 0) { 238 AUTOFS_WARN("vn_vget_ino_gen() failed with error %d", 239 error); 240 return (error); 241 } 242 return (error); 243 } 244 245 if (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') { 246 vref(dvp); 247 *vpp = dvp; 248 249 return (0); 250 } 251 252 if (autofs_cached(anp, cnp->cn_nameptr, cnp->cn_namelen) == false && 253 autofs_ignore_thread(curthread) == false) { 254 error = autofs_trigger_vn(dvp, 255 cnp->cn_nameptr, cnp->cn_namelen, &newvp); 256 if (error != 0) 257 return (error); 258 259 if (newvp != NULL) { 260 /* 261 * The target filesystem got automounted. 262 * Let the lookup(9) go around with the same 263 * path component. 264 */ 265 vput(newvp); 266 return (ERELOOKUP); 267 } 268 } 269 270 AUTOFS_SLOCK(amp); 271 error = autofs_node_find(anp, cnp->cn_nameptr, cnp->cn_namelen, &child); 272 if (error != 0) { 273 if ((cnp->cn_flags & ISLASTCN) && cnp->cn_nameiop == CREATE) { 274 AUTOFS_SUNLOCK(amp); 275 return (EJUSTRETURN); 276 } 277 278 AUTOFS_SUNLOCK(amp); 279 return (ENOENT); 280 } 281 282 /* 283 * XXX: Dropping the node here is ok, because we never remove nodes. 284 */ 285 AUTOFS_SUNLOCK(amp); 286 287 error = autofs_node_vn(child, mp, cnp->cn_lkflags, vpp); 288 if (error != 0) { 289 if ((cnp->cn_flags & ISLASTCN) && cnp->cn_nameiop == CREATE) 290 return (EJUSTRETURN); 291 292 return (error); 293 } 294 295 return (0); 296 } 297 298 static int 299 autofs_mkdir(struct vop_mkdir_args *ap) 300 { 301 struct vnode *vp; 302 struct autofs_node *anp; 303 struct autofs_mount *amp; 304 struct autofs_node *child; 305 int error; 306 307 vp = ap->a_dvp; 308 anp = vp->v_data; 309 amp = VFSTOAUTOFS(vp->v_mount); 310 311 /* 312 * Do not allow mkdir() if the calling thread is not 313 * automountd(8) descendant. 314 */ 315 if (autofs_ignore_thread(curthread) == false) 316 return (EPERM); 317 318 AUTOFS_XLOCK(amp); 319 error = autofs_node_new(anp, amp, ap->a_cnp->cn_nameptr, 320 ap->a_cnp->cn_namelen, &child); 321 if (error != 0) { 322 AUTOFS_XUNLOCK(amp); 323 return (error); 324 } 325 AUTOFS_XUNLOCK(amp); 326 327 error = autofs_node_vn(child, vp->v_mount, LK_EXCLUSIVE, ap->a_vpp); 328 329 return (error); 330 } 331 332 static int 333 autofs_print(struct vop_print_args *ap) 334 { 335 struct vnode *vp; 336 struct autofs_node *anp; 337 338 vp = ap->a_vp; 339 anp = vp->v_data; 340 341 printf(" name \"%s\", fileno %d, cached %d, wildcards %d\n", 342 anp->an_name, anp->an_fileno, anp->an_cached, anp->an_wildcards); 343 344 return (0); 345 } 346 347 /* 348 * Write out a single 'struct dirent', based on 'name' and 'fileno' arguments. 349 */ 350 static int 351 autofs_readdir_one(struct uio *uio, const char *name, int fileno, 352 size_t *reclenp) 353 { 354 struct dirent dirent; 355 size_t namlen, reclen; 356 int error; 357 358 namlen = strlen(name); 359 reclen = _GENERIC_DIRLEN(namlen); 360 if (reclenp != NULL) 361 *reclenp = reclen; 362 363 if (uio == NULL) 364 return (0); 365 366 if (uio->uio_resid < reclen) 367 return (EINVAL); 368 369 dirent.d_fileno = fileno; 370 dirent.d_off = uio->uio_offset + reclen; 371 dirent.d_reclen = reclen; 372 dirent.d_type = DT_DIR; 373 dirent.d_namlen = namlen; 374 memcpy(dirent.d_name, name, namlen); 375 dirent_terminate(&dirent); 376 error = uiomove(&dirent, reclen, uio); 377 378 return (error); 379 } 380 381 static size_t 382 autofs_dirent_reclen(const char *name) 383 { 384 size_t reclen; 385 386 (void)autofs_readdir_one(NULL, name, -1, &reclen); 387 388 return (reclen); 389 } 390 391 static int 392 autofs_readdir(struct vop_readdir_args *ap) 393 { 394 struct vnode *vp, *newvp; 395 struct autofs_mount *amp; 396 struct autofs_node *anp, *child; 397 struct uio *uio; 398 size_t reclen, reclens; 399 ssize_t initial_resid; 400 int error; 401 402 vp = ap->a_vp; 403 amp = VFSTOAUTOFS(vp->v_mount); 404 anp = vp->v_data; 405 uio = ap->a_uio; 406 initial_resid = ap->a_uio->uio_resid; 407 408 KASSERT(vp->v_type == VDIR, ("!VDIR")); 409 410 if (autofs_cached(anp, NULL, 0) == false && 411 autofs_ignore_thread(curthread) == false) { 412 error = autofs_trigger_vn(vp, "", 0, &newvp); 413 if (error != 0) 414 return (error); 415 416 if (newvp != NULL) { 417 error = VOP_READDIR(newvp, ap->a_uio, ap->a_cred, 418 ap->a_eofflag, ap->a_ncookies, ap->a_cookies); 419 vput(newvp); 420 return (error); 421 } 422 } 423 424 if (uio->uio_offset < 0) 425 return (EINVAL); 426 427 if (ap->a_eofflag != NULL) 428 *ap->a_eofflag = FALSE; 429 430 /* 431 * Write out the directory entry for ".". This is conditional 432 * on the current offset into the directory; same applies to the 433 * other two cases below. 434 */ 435 if (uio->uio_offset == 0) { 436 error = autofs_readdir_one(uio, ".", anp->an_fileno, &reclen); 437 if (error != 0) 438 goto out; 439 } 440 reclens = autofs_dirent_reclen("."); 441 442 /* 443 * Write out the directory entry for "..". 444 */ 445 if (uio->uio_offset <= reclens) { 446 if (uio->uio_offset != reclens) 447 return (EINVAL); 448 if (anp->an_parent == NULL) { 449 error = autofs_readdir_one(uio, "..", 450 anp->an_fileno, &reclen); 451 } else { 452 error = autofs_readdir_one(uio, "..", 453 anp->an_parent->an_fileno, &reclen); 454 } 455 if (error != 0) 456 goto out; 457 } 458 459 reclens += autofs_dirent_reclen(".."); 460 461 /* 462 * Write out the directory entries for subdirectories. 463 */ 464 AUTOFS_SLOCK(amp); 465 RB_FOREACH(child, autofs_node_tree, &anp->an_children) { 466 /* 467 * Check the offset to skip entries returned by previous 468 * calls to getdents(). 469 */ 470 if (uio->uio_offset > reclens) { 471 reclens += autofs_dirent_reclen(child->an_name); 472 continue; 473 } 474 475 /* 476 * Prevent seeking into the middle of dirent. 477 */ 478 if (uio->uio_offset != reclens) { 479 AUTOFS_SUNLOCK(amp); 480 return (EINVAL); 481 } 482 483 error = autofs_readdir_one(uio, child->an_name, 484 child->an_fileno, &reclen); 485 reclens += reclen; 486 if (error != 0) { 487 AUTOFS_SUNLOCK(amp); 488 goto out; 489 } 490 } 491 AUTOFS_SUNLOCK(amp); 492 493 if (ap->a_eofflag != NULL) 494 *ap->a_eofflag = TRUE; 495 496 return (0); 497 498 out: 499 /* 500 * Return error if the initial buffer was too small to do anything. 501 */ 502 if (uio->uio_resid == initial_resid) 503 return (error); 504 505 /* 506 * Don't return an error if we managed to copy out some entries. 507 */ 508 if (uio->uio_resid < reclen) 509 return (0); 510 511 return (error); 512 } 513 514 static int 515 autofs_reclaim(struct vop_reclaim_args *ap) 516 { 517 struct vnode *vp; 518 struct autofs_node *anp; 519 520 vp = ap->a_vp; 521 anp = vp->v_data; 522 523 /* 524 * We do not free autofs_node here; instead we are 525 * destroying them in autofs_node_delete(). 526 */ 527 sx_xlock(&anp->an_vnode_lock); 528 anp->an_vnode = NULL; 529 vp->v_data = NULL; 530 sx_xunlock(&anp->an_vnode_lock); 531 532 return (0); 533 } 534 535 struct vop_vector autofs_vnodeops = { 536 .vop_default = &default_vnodeops, 537 538 .vop_access = autofs_access, 539 .vop_lookup = autofs_lookup, 540 .vop_create = VOP_EOPNOTSUPP, 541 .vop_getattr = autofs_getattr, 542 .vop_link = VOP_EOPNOTSUPP, 543 .vop_mkdir = autofs_mkdir, 544 .vop_mknod = VOP_EOPNOTSUPP, 545 .vop_print = autofs_print, 546 .vop_read = VOP_EOPNOTSUPP, 547 .vop_readdir = autofs_readdir, 548 .vop_remove = VOP_EOPNOTSUPP, 549 .vop_rename = VOP_EOPNOTSUPP, 550 .vop_rmdir = VOP_EOPNOTSUPP, 551 .vop_setattr = VOP_EOPNOTSUPP, 552 .vop_symlink = VOP_EOPNOTSUPP, 553 .vop_write = VOP_EOPNOTSUPP, 554 .vop_reclaim = autofs_reclaim, 555 }; 556 VFS_VOP_VECTOR_REGISTER(autofs_vnodeops); 557 558 int 559 autofs_node_new(struct autofs_node *parent, struct autofs_mount *amp, 560 const char *name, int namelen, struct autofs_node **anpp) 561 { 562 struct autofs_node *anp; 563 564 if (parent != NULL) { 565 AUTOFS_ASSERT_XLOCKED(parent->an_mount); 566 567 KASSERT(autofs_node_find(parent, name, namelen, NULL) == ENOENT, 568 ("node \"%s\" already exists", name)); 569 } 570 571 anp = uma_zalloc(autofs_node_zone, M_WAITOK | M_ZERO); 572 if (namelen >= 0) 573 anp->an_name = strndup(name, namelen, M_AUTOFS); 574 else 575 anp->an_name = strdup(name, M_AUTOFS); 576 anp->an_fileno = atomic_fetchadd_int(&->am_last_fileno, 1); 577 callout_init(&anp->an_callout, 1); 578 /* 579 * The reason for SX_NOWITNESS here is that witness(4) 580 * cannot tell vnodes apart, so the following perfectly 581 * valid lock order... 582 * 583 * vnode lock A -> autofsvlk B -> vnode lock B 584 * 585 * ... gets reported as a LOR. 586 */ 587 sx_init_flags(&anp->an_vnode_lock, "autofsvlk", SX_NOWITNESS); 588 getnanotime(&anp->an_ctime); 589 anp->an_parent = parent; 590 anp->an_mount = amp; 591 if (parent != NULL) 592 RB_INSERT(autofs_node_tree, &parent->an_children, anp); 593 RB_INIT(&anp->an_children); 594 595 *anpp = anp; 596 return (0); 597 } 598 599 int 600 autofs_node_find(struct autofs_node *parent, const char *name, 601 int namelen, struct autofs_node **anpp) 602 { 603 struct autofs_node *anp, find; 604 int error; 605 606 AUTOFS_ASSERT_LOCKED(parent->an_mount); 607 608 if (namelen >= 0) 609 find.an_name = strndup(name, namelen, M_AUTOFS); 610 else 611 find.an_name = strdup(name, M_AUTOFS); 612 613 anp = RB_FIND(autofs_node_tree, &parent->an_children, &find); 614 if (anp != NULL) { 615 error = 0; 616 if (anpp != NULL) 617 *anpp = anp; 618 } else { 619 error = ENOENT; 620 } 621 622 free(find.an_name, M_AUTOFS); 623 624 return (error); 625 } 626 627 void 628 autofs_node_delete(struct autofs_node *anp) 629 { 630 struct autofs_node *parent; 631 632 AUTOFS_ASSERT_XLOCKED(anp->an_mount); 633 KASSERT(RB_EMPTY(&anp->an_children), ("have children")); 634 635 callout_drain(&anp->an_callout); 636 637 parent = anp->an_parent; 638 if (parent != NULL) 639 RB_REMOVE(autofs_node_tree, &parent->an_children, anp); 640 sx_destroy(&anp->an_vnode_lock); 641 free(anp->an_name, M_AUTOFS); 642 uma_zfree(autofs_node_zone, anp); 643 } 644 645 int 646 autofs_node_vn(struct autofs_node *anp, struct mount *mp, int flags, 647 struct vnode **vpp) 648 { 649 struct vnode *vp; 650 int error; 651 652 AUTOFS_ASSERT_UNLOCKED(anp->an_mount); 653 654 sx_xlock(&anp->an_vnode_lock); 655 656 vp = anp->an_vnode; 657 if (vp != NULL) { 658 error = vget(vp, flags | LK_RETRY); 659 if (error != 0) { 660 AUTOFS_WARN("vget failed with error %d", error); 661 sx_xunlock(&anp->an_vnode_lock); 662 return (error); 663 } 664 if (VN_IS_DOOMED(vp)) { 665 /* 666 * We got forcibly unmounted. 667 */ 668 AUTOFS_DEBUG("doomed vnode"); 669 sx_xunlock(&anp->an_vnode_lock); 670 vput(vp); 671 672 return (ENOENT); 673 } 674 675 *vpp = vp; 676 sx_xunlock(&anp->an_vnode_lock); 677 return (0); 678 } 679 680 error = getnewvnode("autofs", mp, &autofs_vnodeops, &vp); 681 if (error != 0) { 682 sx_xunlock(&anp->an_vnode_lock); 683 return (error); 684 } 685 686 error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 687 if (error != 0) { 688 sx_xunlock(&anp->an_vnode_lock); 689 vdrop(vp); 690 return (error); 691 } 692 693 vp->v_type = VDIR; 694 if (anp->an_parent == NULL) 695 vp->v_vflag |= VV_ROOT; 696 vp->v_data = anp; 697 698 VN_LOCK_ASHARE(vp); 699 700 error = insmntque(vp, mp); 701 if (error != 0) { 702 AUTOFS_DEBUG("insmntque() failed with error %d", error); 703 sx_xunlock(&anp->an_vnode_lock); 704 return (error); 705 } 706 707 KASSERT(anp->an_vnode == NULL, ("lost race")); 708 anp->an_vnode = vp; 709 710 sx_xunlock(&anp->an_vnode_lock); 711 712 *vpp = vp; 713 return (0); 714 } 715