autofs_vnops.c revision 296715
1/*- 2 * Copyright (c) 2014 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Edward Tomasz Napierala under sponsorship 6 * from the FreeBSD Foundation. 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 */ 30 31#include <sys/cdefs.h> 32__FBSDID("$FreeBSD: head/sys/fs/autofs/autofs_vnops.c 296715 2016-03-12 07:54:42Z trasz $"); 33 34#include <sys/param.h> 35#include <sys/kernel.h> 36#include <sys/condvar.h> 37#include <sys/dirent.h> 38#include <sys/fcntl.h> 39#include <sys/lock.h> 40#include <sys/mount.h> 41#include <sys/mutex.h> 42#include <sys/namei.h> 43#include <sys/signalvar.h> 44#include <sys/systm.h> 45#include <sys/taskqueue.h> 46#include <sys/vnode.h> 47#include <machine/atomic.h> 48#include <vm/uma.h> 49 50#include <fs/autofs/autofs.h> 51 52static int autofs_trigger_vn(struct vnode *vp, const char *path, 53 int pathlen, struct vnode **newvp); 54 55extern struct autofs_softc *autofs_softc; 56 57static int 58autofs_access(struct vop_access_args *ap) 59{ 60 61 /* 62 * Nothing to do here; the only kind of access control 63 * needed is in autofs_mkdir(). 64 */ 65 66 return (0); 67} 68 69static int 70autofs_getattr(struct vop_getattr_args *ap) 71{ 72 struct vnode *vp, *newvp; 73 struct autofs_node *anp; 74 struct mount *mp; 75 struct vattr *vap; 76 int error; 77 78 vp = ap->a_vp; 79 anp = vp->v_data; 80 mp = vp->v_mount; 81 vap = ap->a_vap; 82 83 KASSERT(ap->a_vp->v_type == VDIR, ("!VDIR")); 84 85 /* 86 * The reason we must do this is that some tree-walking software, 87 * namely fts(3), assumes that stat(".") results will not change 88 * between chdir("subdir") and chdir(".."), and fails with ENOENT 89 * otherwise. 90 */ 91 if (autofs_mount_on_stat && autofs_cached(anp, NULL, 0) == false && 92 autofs_ignore_thread(curthread) == false) { 93 error = autofs_trigger_vn(vp, "", 0, &newvp); 94 if (error != 0) 95 return (error); 96 97 if (newvp != NULL) { 98 error = VOP_GETATTR(newvp, ap->a_vap, 99 ap->a_cred); 100 vput(newvp); 101 return (error); 102 } 103 } 104 105 vap->va_type = VDIR; 106 vap->va_mode = 0755; 107 vap->va_nlink = 3; /* XXX */ 108 vap->va_uid = 0; 109 vap->va_gid = 0; 110 vap->va_rdev = NODEV; 111 vap->va_fsid = mp->mnt_stat.f_fsid.val[0]; 112 vap->va_fileid = anp->an_fileno; 113 vap->va_size = 512; /* XXX */ 114 vap->va_blocksize = 512; 115 vap->va_mtime = anp->an_ctime; 116 vap->va_atime = anp->an_ctime; 117 vap->va_ctime = anp->an_ctime; 118 vap->va_birthtime = anp->an_ctime; 119 vap->va_gen = 0; 120 vap->va_flags = 0; 121 vap->va_rdev = 0; 122 vap->va_bytes = 512; /* XXX */ 123 vap->va_filerev = 0; 124 vap->va_spare = 0; 125 126 return (0); 127} 128 129/* 130 * Unlock the vnode, request automountd(8) action, and then lock it back. 131 * If anything got mounted on top of the vnode, return the new filesystem's 132 * root vnode in 'newvp', locked. 133 */ 134static int 135autofs_trigger_vn(struct vnode *vp, const char *path, int pathlen, 136 struct vnode **newvp) 137{ 138 struct autofs_node *anp; 139 struct autofs_mount *amp; 140 int error, lock_flags; 141 142 anp = vp->v_data; 143 amp = VFSTOAUTOFS(vp->v_mount); 144 145 /* 146 * Release the vnode lock, so that other operations, in partcular 147 * mounting a filesystem on top of it, can proceed. Increase use 148 * count, to prevent the vnode from being deallocated and to prevent 149 * filesystem from being unmounted. 150 */ 151 lock_flags = VOP_ISLOCKED(vp); 152 vref(vp); 153 VOP_UNLOCK(vp, 0); 154 155 sx_xlock(&autofs_softc->sc_lock); 156 157 /* 158 * XXX: Workaround for mounting the same thing multiple times; revisit. 159 */ 160 if (vp->v_mountedhere != NULL) { 161 error = 0; 162 goto mounted; 163 } 164 165 error = autofs_trigger(anp, path, pathlen); 166mounted: 167 sx_xunlock(&autofs_softc->sc_lock); 168 vn_lock(vp, lock_flags | LK_RETRY); 169 vunref(vp); 170 if ((vp->v_iflag & VI_DOOMED) != 0) { 171 AUTOFS_DEBUG("VI_DOOMED"); 172 return (ENOENT); 173 } 174 175 if (error != 0) 176 return (error); 177 178 if (vp->v_mountedhere == NULL) { 179 *newvp = NULL; 180 return (0); 181 } else { 182 /* 183 * If the operation that succeeded was mount, then mark 184 * the node as non-cached. Otherwise, if someone unmounts 185 * the filesystem before the cache times out, we will fail 186 * to trigger. 187 */ 188 anp->an_cached = false; 189 } 190 191 error = VFS_ROOT(vp->v_mountedhere, lock_flags, newvp); 192 if (error != 0) { 193 AUTOFS_WARN("VFS_ROOT() failed with error %d", error); 194 return (error); 195 } 196 197 return (0); 198} 199 200static int 201autofs_vget_callback(struct mount *mp, void *arg, int flags, 202 struct vnode **vpp) 203{ 204 205 206 return (autofs_node_vn(arg, mp, flags, vpp)); 207} 208 209static int 210autofs_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(cnp->cn_thread) == 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 298static int 299autofs_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 332static int 333autofs_readdir_one(struct uio *uio, const char *name, int fileno) 334{ 335 struct dirent dirent; 336 int error, i; 337 338 memset(&dirent, 0, sizeof(dirent)); 339 dirent.d_type = DT_DIR; 340 dirent.d_reclen = AUTOFS_DELEN; 341 dirent.d_fileno = fileno; 342 /* PFS_DELEN was picked to fit PFS_NAMLEN */ 343 for (i = 0; i < AUTOFS_NAMELEN - 1 && name[i] != '\0'; ++i) 344 dirent.d_name[i] = name[i]; 345 dirent.d_name[i] = 0; 346 dirent.d_namlen = i; 347 348 error = uiomove(&dirent, AUTOFS_DELEN, uio); 349 return (error); 350} 351 352static int 353autofs_readdir(struct vop_readdir_args *ap) 354{ 355 struct vnode *vp, *newvp; 356 struct autofs_mount *amp; 357 struct autofs_node *anp, *child; 358 struct uio *uio; 359 off_t offset; 360 int error, i, resid; 361 362 vp = ap->a_vp; 363 amp = VFSTOAUTOFS(vp->v_mount); 364 anp = vp->v_data; 365 uio = ap->a_uio; 366 367 KASSERT(vp->v_type == VDIR, ("!VDIR")); 368 369 if (autofs_cached(anp, NULL, 0) == false && 370 autofs_ignore_thread(curthread) == false) { 371 error = autofs_trigger_vn(vp, "", 0, &newvp); 372 if (error != 0) 373 return (error); 374 375 if (newvp != NULL) { 376 error = VOP_READDIR(newvp, ap->a_uio, ap->a_cred, 377 ap->a_eofflag, ap->a_ncookies, ap->a_cookies); 378 vput(newvp); 379 return (error); 380 } 381 } 382 383 /* only allow reading entire entries */ 384 offset = uio->uio_offset; 385 resid = uio->uio_resid; 386 if (offset < 0 || offset % AUTOFS_DELEN != 0 || 387 (resid && resid < AUTOFS_DELEN)) 388 return (EINVAL); 389 if (resid == 0) 390 return (0); 391 392 if (ap->a_eofflag != NULL) 393 *ap->a_eofflag = TRUE; 394 395 if (offset == 0 && resid >= AUTOFS_DELEN) { 396 error = autofs_readdir_one(uio, ".", anp->an_fileno); 397 if (error != 0) 398 return (error); 399 offset += AUTOFS_DELEN; 400 resid -= AUTOFS_DELEN; 401 } 402 403 if (offset == AUTOFS_DELEN && resid >= AUTOFS_DELEN) { 404 if (anp->an_parent == NULL) { 405 /* 406 * XXX: Right? 407 */ 408 error = autofs_readdir_one(uio, "..", anp->an_fileno); 409 } else { 410 error = autofs_readdir_one(uio, "..", 411 anp->an_parent->an_fileno); 412 } 413 if (error != 0) 414 return (error); 415 offset += AUTOFS_DELEN; 416 resid -= AUTOFS_DELEN; 417 } 418 419 i = 2; /* Account for "." and "..". */ 420 AUTOFS_SLOCK(amp); 421 TAILQ_FOREACH(child, &anp->an_children, an_next) { 422 if (resid < AUTOFS_DELEN) { 423 if (ap->a_eofflag != NULL) 424 *ap->a_eofflag = 0; 425 break; 426 } 427 428 /* 429 * Skip entries returned by previous call to getdents(). 430 */ 431 i++; 432 if (i * AUTOFS_DELEN <= offset) 433 continue; 434 435 error = autofs_readdir_one(uio, child->an_name, 436 child->an_fileno); 437 if (error != 0) { 438 AUTOFS_SUNLOCK(amp); 439 return (error); 440 } 441 offset += AUTOFS_DELEN; 442 resid -= AUTOFS_DELEN; 443 } 444 445 AUTOFS_SUNLOCK(amp); 446 return (0); 447} 448 449static int 450autofs_reclaim(struct vop_reclaim_args *ap) 451{ 452 struct vnode *vp; 453 struct autofs_node *anp; 454 455 vp = ap->a_vp; 456 anp = vp->v_data; 457 458 /* 459 * We do not free autofs_node here; instead we are 460 * destroying them in autofs_node_delete(). 461 */ 462 sx_xlock(&anp->an_vnode_lock); 463 anp->an_vnode = NULL; 464 vp->v_data = NULL; 465 sx_xunlock(&anp->an_vnode_lock); 466 467 return (0); 468} 469 470struct vop_vector autofs_vnodeops = { 471 .vop_default = &default_vnodeops, 472 473 .vop_access = autofs_access, 474 .vop_lookup = autofs_lookup, 475 .vop_create = VOP_EOPNOTSUPP, 476 .vop_getattr = autofs_getattr, 477 .vop_link = VOP_EOPNOTSUPP, 478 .vop_mkdir = autofs_mkdir, 479 .vop_mknod = VOP_EOPNOTSUPP, 480 .vop_read = VOP_EOPNOTSUPP, 481 .vop_readdir = autofs_readdir, 482 .vop_remove = VOP_EOPNOTSUPP, 483 .vop_rename = VOP_EOPNOTSUPP, 484 .vop_rmdir = VOP_EOPNOTSUPP, 485 .vop_setattr = VOP_EOPNOTSUPP, 486 .vop_symlink = VOP_EOPNOTSUPP, 487 .vop_write = VOP_EOPNOTSUPP, 488 .vop_reclaim = autofs_reclaim, 489}; 490 491int 492autofs_node_new(struct autofs_node *parent, struct autofs_mount *amp, 493 const char *name, int namelen, struct autofs_node **anpp) 494{ 495 struct autofs_node *anp; 496 497 if (parent != NULL) { 498 AUTOFS_ASSERT_XLOCKED(parent->an_mount); 499 500 KASSERT(autofs_node_find(parent, name, namelen, NULL) == ENOENT, 501 ("node \"%s\" already exists", name)); 502 } 503 504 anp = uma_zalloc(autofs_node_zone, M_WAITOK | M_ZERO); 505 if (namelen >= 0) 506 anp->an_name = strndup(name, namelen, M_AUTOFS); 507 else 508 anp->an_name = strdup(name, M_AUTOFS); 509 anp->an_fileno = atomic_fetchadd_int(&->am_last_fileno, 1); 510 callout_init(&anp->an_callout, 1); 511 /* 512 * The reason for SX_NOWITNESS here is that witness(4) 513 * cannot tell vnodes apart, so the following perfectly 514 * valid lock order... 515 * 516 * vnode lock A -> autofsvlk B -> vnode lock B 517 * 518 * ... gets reported as a LOR. 519 */ 520 sx_init_flags(&anp->an_vnode_lock, "autofsvlk", SX_NOWITNESS); 521 getnanotime(&anp->an_ctime); 522 anp->an_parent = parent; 523 anp->an_mount = amp; 524 if (parent != NULL) 525 TAILQ_INSERT_TAIL(&parent->an_children, anp, an_next); 526 TAILQ_INIT(&anp->an_children); 527 528 *anpp = anp; 529 return (0); 530} 531 532int 533autofs_node_find(struct autofs_node *parent, const char *name, 534 int namelen, struct autofs_node **anpp) 535{ 536 struct autofs_node *anp; 537 538 AUTOFS_ASSERT_LOCKED(parent->an_mount); 539 540 TAILQ_FOREACH(anp, &parent->an_children, an_next) { 541 if (namelen >= 0) { 542 if (strlen(anp->an_name) != namelen) 543 continue; 544 if (strncmp(anp->an_name, name, namelen) != 0) 545 continue; 546 } else { 547 if (strcmp(anp->an_name, name) != 0) 548 continue; 549 } 550 551 if (anpp != NULL) 552 *anpp = anp; 553 return (0); 554 } 555 556 return (ENOENT); 557} 558 559void 560autofs_node_delete(struct autofs_node *anp) 561{ 562 struct autofs_node *parent; 563 564 AUTOFS_ASSERT_XLOCKED(anp->an_mount); 565 KASSERT(TAILQ_EMPTY(&anp->an_children), ("have children")); 566 567 callout_drain(&anp->an_callout); 568 569 parent = anp->an_parent; 570 if (parent != NULL) 571 TAILQ_REMOVE(&parent->an_children, anp, an_next); 572 sx_destroy(&anp->an_vnode_lock); 573 free(anp->an_name, M_AUTOFS); 574 uma_zfree(autofs_node_zone, anp); 575} 576 577int 578autofs_node_vn(struct autofs_node *anp, struct mount *mp, int flags, 579 struct vnode **vpp) 580{ 581 struct vnode *vp; 582 int error; 583 584 AUTOFS_ASSERT_UNLOCKED(anp->an_mount); 585 586 sx_xlock(&anp->an_vnode_lock); 587 588 vp = anp->an_vnode; 589 if (vp != NULL) { 590 error = vget(vp, flags | LK_RETRY, curthread); 591 if (error != 0) { 592 AUTOFS_WARN("vget failed with error %d", error); 593 sx_xunlock(&anp->an_vnode_lock); 594 return (error); 595 } 596 if (vp->v_iflag & VI_DOOMED) { 597 /* 598 * We got forcibly unmounted. 599 */ 600 AUTOFS_DEBUG("doomed vnode"); 601 sx_xunlock(&anp->an_vnode_lock); 602 vput(vp); 603 604 return (ENOENT); 605 } 606 607 *vpp = vp; 608 sx_xunlock(&anp->an_vnode_lock); 609 return (0); 610 } 611 612 error = getnewvnode("autofs", mp, &autofs_vnodeops, &vp); 613 if (error != 0) { 614 sx_xunlock(&anp->an_vnode_lock); 615 return (error); 616 } 617 618 error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 619 if (error != 0) { 620 sx_xunlock(&anp->an_vnode_lock); 621 vdrop(vp); 622 return (error); 623 } 624 625 vp->v_type = VDIR; 626 if (anp->an_parent == NULL) 627 vp->v_vflag |= VV_ROOT; 628 vp->v_data = anp; 629 630 VN_LOCK_ASHARE(vp); 631 632 error = insmntque(vp, mp); 633 if (error != 0) { 634 AUTOFS_WARN("insmntque() failed with error %d", error); 635 sx_xunlock(&anp->an_vnode_lock); 636 return (error); 637 } 638 639 KASSERT(anp->an_vnode == NULL, ("lost race")); 640 anp->an_vnode = vp; 641 642 sx_xunlock(&anp->an_vnode_lock); 643 644 *vpp = vp; 645 return (0); 646} 647