autofs_vnops.c revision 270207
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 * $FreeBSD: head/sys/fs/autofs/autofs_vnops.c 270207 2014-08-20 13:46:51Z trasz $ 30 */ 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: head/sys/fs/autofs/autofs_vnops.c 270207 2014-08-20 13:46:51Z trasz $"); 34 35#include <sys/param.h> 36#include <sys/kernel.h> 37#include <sys/condvar.h> 38#include <sys/dirent.h> 39#include <sys/fcntl.h> 40#include <sys/lock.h> 41#include <sys/mount.h> 42#include <sys/mutex.h> 43#include <sys/namei.h> 44#include <sys/signalvar.h> 45#include <sys/systm.h> 46#include <sys/vnode.h> 47#include <machine/atomic.h> 48#include <vm/uma.h> 49 50#include "autofs.h" 51 52static int autofs_trigger_vn(struct vnode *vp, const char *path, 53 int pathlen, struct vnode **newvp); 54 55static int 56autofs_access(struct vop_access_args *ap) 57{ 58 59 /* 60 * Nothing to do here; the only kind of access control 61 * needed is in autofs_mkdir(). 62 */ 63 64 return (0); 65} 66 67static int 68autofs_getattr(struct vop_getattr_args *ap) 69{ 70 struct vnode *vp, *newvp; 71 struct autofs_node *anp; 72 struct mount *mp; 73 struct vattr *vap; 74 int error; 75 76 vp = ap->a_vp; 77 anp = vp->v_data; 78 mp = vp->v_mount; 79 vap = ap->a_vap; 80 81 KASSERT(ap->a_vp->v_type == VDIR, ("!VDIR")); 82 83 /* 84 * The reason we must do this is that some tree-walking software, 85 * namely fts(3), assumes that stat(".") results will not change 86 * between chdir("subdir") and chdir(".."), and fails with ENOENT 87 * otherwise. 88 */ 89 if (autofs_mount_on_stat && autofs_cached(anp, NULL, 0) == false && 90 autofs_ignore_thread(curthread) == false) { 91 error = autofs_trigger_vn(vp, "", 0, &newvp); 92 if (error != 0) 93 return (error); 94 95 if (newvp != NULL) { 96 error = VOP_GETATTR(newvp, ap->a_vap, 97 ap->a_cred); 98 vput(newvp); 99 return (error); 100 } 101 } 102 103 vap->va_type = VDIR; 104 vap->va_mode = 0755; 105 vap->va_nlink = 3; /* XXX */ 106 vap->va_uid = 0; 107 vap->va_gid = 0; 108 vap->va_rdev = NODEV; 109 vap->va_fsid = mp->mnt_stat.f_fsid.val[0]; 110 vap->va_fileid = anp->an_fileno; 111 vap->va_size = 512; /* XXX */ 112 vap->va_blocksize = 512; 113 vap->va_mtime = anp->an_ctime; 114 vap->va_atime = anp->an_ctime; 115 vap->va_ctime = anp->an_ctime; 116 vap->va_birthtime = anp->an_ctime; 117 vap->va_gen = 0; 118 vap->va_flags = 0; 119 vap->va_rdev = 0; 120 vap->va_bytes = 512; /* XXX */ 121 vap->va_filerev = 0; 122 vap->va_spare = 0; 123 124 return (0); 125} 126 127/* 128 * Unlock the vnode, request automountd(8) action, and then lock it back. 129 * If anything got mounted on top of the vnode, return the new filesystem's 130 * root vnode in 'newvp', locked. 131 */ 132static int 133autofs_trigger_vn(struct vnode *vp, const char *path, int pathlen, 134 struct vnode **newvp) 135{ 136 struct autofs_node *anp; 137 struct autofs_mount *amp; 138 struct autofs_softc *sc; 139 int error, lock_flags; 140 141 anp = vp->v_data; 142 amp = VFSTOAUTOFS(vp->v_mount); 143 sc = amp->am_softc; 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(&sc->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(&sc->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 lkflags __unused, 202 struct vnode **vpp) 203{ 204 205 206 return (autofs_node_vn(arg, mp, 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, lock_flags; 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, 0, 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 error = VOP_LOOKUP(newvp, ap->a_vpp, ap->a_cnp); 261 262 /* 263 * Instead of figuring out whether our vnode should 264 * be locked or not given the error and cnp flags, 265 * just "copy" the lock status from vnode returned 266 * by mounted filesystem's VOP_LOOKUP(). Get rid 267 * of that new vnode afterwards. 268 */ 269 lock_flags = VOP_ISLOCKED(newvp); 270 if (lock_flags == 0) { 271 VOP_UNLOCK(dvp, 0); 272 vrele(newvp); 273 } else { 274 vput(newvp); 275 } 276 return (error); 277 } 278 } 279 280 if (cnp->cn_nameiop == RENAME) 281 return (EOPNOTSUPP); 282 283 AUTOFS_LOCK(amp); 284 error = autofs_node_find(anp, cnp->cn_nameptr, cnp->cn_namelen, &child); 285 if (error != 0) { 286 if ((cnp->cn_flags & ISLASTCN) && cnp->cn_nameiop == CREATE) { 287 AUTOFS_UNLOCK(amp); 288 return (EJUSTRETURN); 289 } 290 291 AUTOFS_UNLOCK(amp); 292 return (ENOENT); 293 } 294 295 /* 296 * XXX: Dropping the node here is ok, because we never remove nodes. 297 */ 298 AUTOFS_UNLOCK(amp); 299 300 error = autofs_node_vn(child, mp, vpp); 301 if (error != 0) { 302 if ((cnp->cn_flags & ISLASTCN) && cnp->cn_nameiop == CREATE) 303 return (EJUSTRETURN); 304 305 return (error); 306 } 307 308 return (0); 309} 310 311static int 312autofs_mkdir(struct vop_mkdir_args *ap) 313{ 314 struct vnode *vp; 315 struct autofs_node *anp; 316 struct autofs_mount *amp; 317 struct autofs_node *child; 318 int error; 319 320 vp = ap->a_dvp; 321 anp = vp->v_data; 322 amp = VFSTOAUTOFS(vp->v_mount); 323 324 /* 325 * Do not allow mkdir() if the calling thread is not 326 * automountd(8) descendant. 327 */ 328 if (autofs_ignore_thread(curthread) == false) 329 return (EPERM); 330 331 AUTOFS_LOCK(amp); 332 error = autofs_node_new(anp, amp, ap->a_cnp->cn_nameptr, 333 ap->a_cnp->cn_namelen, &child); 334 if (error != 0) { 335 AUTOFS_UNLOCK(amp); 336 return (error); 337 } 338 AUTOFS_UNLOCK(amp); 339 340 error = autofs_node_vn(child, vp->v_mount, ap->a_vpp); 341 342 return (error); 343} 344 345static int 346autofs_readdir_one(struct uio *uio, const char *name, int fileno) 347{ 348 struct dirent dirent; 349 int error, i; 350 351 memset(&dirent, 0, sizeof(dirent)); 352 dirent.d_type = DT_DIR; 353 dirent.d_reclen = AUTOFS_DELEN; 354 dirent.d_fileno = fileno; 355 /* PFS_DELEN was picked to fit PFS_NAMLEN */ 356 for (i = 0; i < AUTOFS_NAMELEN - 1 && name[i] != '\0'; ++i) 357 dirent.d_name[i] = name[i]; 358 dirent.d_name[i] = 0; 359 dirent.d_namlen = i; 360 361 error = uiomove(&dirent, AUTOFS_DELEN, uio); 362 return (error); 363} 364 365static int 366autofs_readdir(struct vop_readdir_args *ap) 367{ 368 struct vnode *vp, *newvp; 369 struct autofs_mount *amp; 370 struct autofs_node *anp, *child; 371 struct uio *uio; 372 off_t offset; 373 int error, i, resid; 374 375 vp = ap->a_vp; 376 amp = VFSTOAUTOFS(vp->v_mount); 377 anp = vp->v_data; 378 uio = ap->a_uio; 379 380 KASSERT(vp->v_type == VDIR, ("!VDIR")); 381 382 if (autofs_cached(anp, NULL, 0) == false && 383 autofs_ignore_thread(curthread) == false) { 384 error = autofs_trigger_vn(vp, "", 0, &newvp); 385 if (error != 0) 386 return (error); 387 388 if (newvp != NULL) { 389 error = VOP_READDIR(newvp, ap->a_uio, ap->a_cred, 390 ap->a_eofflag, ap->a_ncookies, ap->a_cookies); 391 vput(newvp); 392 return (error); 393 } 394 } 395 396 /* only allow reading entire entries */ 397 offset = uio->uio_offset; 398 resid = uio->uio_resid; 399 if (offset < 0 || offset % AUTOFS_DELEN != 0 || 400 (resid && resid < AUTOFS_DELEN)) 401 return (EINVAL); 402 if (resid == 0) 403 return (0); 404 405 if (ap->a_eofflag != NULL) 406 *ap->a_eofflag = TRUE; 407 408 if (offset == 0 && resid >= AUTOFS_DELEN) { 409 error = autofs_readdir_one(uio, ".", anp->an_fileno); 410 if (error != 0) 411 return (error); 412 offset += AUTOFS_DELEN; 413 resid -= AUTOFS_DELEN; 414 } 415 416 if (offset == AUTOFS_DELEN && resid >= AUTOFS_DELEN) { 417 if (anp->an_parent == NULL) { 418 /* 419 * XXX: Right? 420 */ 421 error = autofs_readdir_one(uio, "..", anp->an_fileno); 422 } else { 423 error = autofs_readdir_one(uio, "..", 424 anp->an_parent->an_fileno); 425 } 426 if (error != 0) 427 return (error); 428 offset += AUTOFS_DELEN; 429 resid -= AUTOFS_DELEN; 430 } 431 432 i = 2; /* Account for "." and "..". */ 433 AUTOFS_LOCK(amp); 434 TAILQ_FOREACH(child, &anp->an_children, an_next) { 435 if (resid < AUTOFS_DELEN) { 436 if (ap->a_eofflag != NULL) 437 *ap->a_eofflag = 0; 438 break; 439 } 440 441 /* 442 * Skip entries returned by previous call to getdents(). 443 */ 444 i++; 445 if (i * AUTOFS_DELEN <= offset) 446 continue; 447 448 error = autofs_readdir_one(uio, child->an_name, 449 child->an_fileno); 450 if (error != 0) { 451 AUTOFS_UNLOCK(amp); 452 return (error); 453 } 454 offset += AUTOFS_DELEN; 455 resid -= AUTOFS_DELEN; 456 } 457 458 AUTOFS_UNLOCK(amp); 459 return (0); 460} 461 462static int 463autofs_reclaim(struct vop_reclaim_args *ap) 464{ 465 struct vnode *vp = ap->a_vp; 466 struct autofs_node *anp = vp->v_data; 467 468 vp = ap->a_vp; 469 anp = vp->v_data; 470 471 /* 472 * We do not free autofs_node here; instead we are 473 * destroying them in autofs_node_delete(). 474 */ 475 sx_xlock(&anp->an_vnode_lock); 476 anp->an_vnode = NULL; 477 vp->v_data = NULL; 478 sx_xunlock(&anp->an_vnode_lock); 479 480 return (0); 481} 482 483struct vop_vector autofs_vnodeops = { 484 .vop_default = &default_vnodeops, 485 486 .vop_access = autofs_access, 487 .vop_lookup = autofs_lookup, 488 .vop_create = VOP_EOPNOTSUPP, 489 .vop_getattr = autofs_getattr, 490 .vop_link = VOP_EOPNOTSUPP, 491 .vop_mkdir = autofs_mkdir, 492 .vop_mknod = VOP_EOPNOTSUPP, 493 .vop_read = VOP_EOPNOTSUPP, 494 .vop_readdir = autofs_readdir, 495 .vop_remove = VOP_EOPNOTSUPP, 496 .vop_rename = VOP_EOPNOTSUPP, 497 .vop_rmdir = VOP_EOPNOTSUPP, 498 .vop_setattr = VOP_EOPNOTSUPP, 499 .vop_symlink = VOP_EOPNOTSUPP, 500 .vop_write = VOP_EOPNOTSUPP, 501 .vop_reclaim = autofs_reclaim, 502}; 503 504int 505autofs_node_new(struct autofs_node *parent, struct autofs_mount *amp, 506 const char *name, int namelen, struct autofs_node **anpp) 507{ 508 struct autofs_node *anp; 509 510 if (parent != NULL) 511 AUTOFS_ASSERT_LOCKED(parent->an_mount); 512 513 anp = uma_zalloc(autofs_node_zone, M_WAITOK | M_ZERO); 514 if (namelen >= 0) 515 anp->an_name = strndup(name, namelen, M_AUTOFS); 516 else 517 anp->an_name = strdup(name, M_AUTOFS); 518 anp->an_fileno = atomic_fetchadd_int(&->am_last_fileno, 1); 519 callout_init(&anp->an_callout, 1); 520 /* 521 * The reason for SX_NOWITNESS here is that witness(4) 522 * cannot tell vnodes apart, so the following perfectly 523 * valid lock order... 524 * 525 * vnode lock A -> autofsvlk B -> vnode lock B 526 * 527 * ... gets reported as a LOR. 528 */ 529 sx_init_flags(&anp->an_vnode_lock, "autofsvlk", SX_NOWITNESS); 530 getnanotime(&anp->an_ctime); 531 anp->an_parent = parent; 532 anp->an_mount = amp; 533 if (parent != NULL) 534 TAILQ_INSERT_TAIL(&parent->an_children, anp, an_next); 535 TAILQ_INIT(&anp->an_children); 536 537 *anpp = anp; 538 return (0); 539} 540 541int 542autofs_node_find(struct autofs_node *parent, const char *name, 543 int namelen, struct autofs_node **anpp) 544{ 545 struct autofs_node *anp; 546 547 AUTOFS_ASSERT_LOCKED(parent->an_mount); 548 549 TAILQ_FOREACH(anp, &parent->an_children, an_next) { 550 if (namelen >= 0) { 551 if (strncmp(anp->an_name, name, namelen) != 0) 552 continue; 553 } else { 554 if (strcmp(anp->an_name, name) != 0) 555 continue; 556 } 557 558 if (anpp != NULL) 559 *anpp = anp; 560 return (0); 561 } 562 563 return (ENOENT); 564} 565 566void 567autofs_node_delete(struct autofs_node *anp) 568{ 569 struct autofs_node *parent; 570 571 AUTOFS_ASSERT_LOCKED(anp->an_mount); 572 KASSERT(TAILQ_EMPTY(&anp->an_children), ("have children")); 573 574 callout_drain(&anp->an_callout); 575 576 parent = anp->an_parent; 577 if (parent != NULL) 578 TAILQ_REMOVE(&parent->an_children, anp, an_next); 579 sx_destroy(&anp->an_vnode_lock); 580 free(anp->an_name, M_AUTOFS); 581 uma_zfree(autofs_node_zone, anp); 582} 583 584int 585autofs_node_vn(struct autofs_node *anp, struct mount *mp, struct vnode **vpp) 586{ 587 struct vnode *vp; 588 int error; 589 590 AUTOFS_ASSERT_UNLOCKED(anp->an_mount); 591 592 sx_xlock(&anp->an_vnode_lock); 593 594 vp = anp->an_vnode; 595 if (vp != NULL) { 596 error = vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread); 597 if (error != 0) { 598 AUTOFS_WARN("vget failed with error %d", error); 599 sx_xunlock(&anp->an_vnode_lock); 600 return (error); 601 } 602 if (vp->v_iflag & VI_DOOMED) { 603 /* 604 * We got forcibly unmounted. 605 */ 606 AUTOFS_DEBUG("doomed vnode"); 607 sx_xunlock(&anp->an_vnode_lock); 608 vput(vp); 609 610 return (ENOENT); 611 } 612 613 *vpp = vp; 614 sx_xunlock(&anp->an_vnode_lock); 615 return (0); 616 } 617 618 error = getnewvnode("autofs", mp, &autofs_vnodeops, &vp); 619 if (error != 0) { 620 sx_xunlock(&anp->an_vnode_lock); 621 return (error); 622 } 623 624 error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 625 if (error != 0) { 626 sx_xunlock(&anp->an_vnode_lock); 627 vdrop(vp); 628 return (error); 629 } 630 631 vp->v_type = VDIR; 632 if (anp->an_parent == NULL) 633 vp->v_vflag |= VV_ROOT; 634 vp->v_data = anp; 635 636 error = insmntque(vp, mp); 637 if (error != 0) { 638 AUTOFS_WARN("insmntque() failed with error %d", error); 639 sx_xunlock(&anp->an_vnode_lock); 640 return (error); 641 } 642 643 KASSERT(anp->an_vnode == NULL, ("lost race")); 644 anp->an_vnode = vp; 645 646 sx_xunlock(&anp->an_vnode_lock); 647 648 *vpp = vp; 649 return (0); 650} 651