1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94 37 */ 38 39 #include <sys/cdefs.h> 40 __FBSDID("$FreeBSD$"); 41 42 #include "opt_capsicum.h" 43 #include "opt_ktrace.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/kernel.h> 48 #include <sys/capsicum.h> 49 #include <sys/fcntl.h> 50 #include <sys/jail.h> 51 #include <sys/lock.h> 52 #include <sys/mutex.h> 53 #include <sys/namei.h> 54 #include <sys/vnode.h> 55 #include <sys/mount.h> 56 #include <sys/filedesc.h> 57 #include <sys/proc.h> 58 #include <sys/sdt.h> 59 #include <sys/syscallsubr.h> 60 #include <sys/sysctl.h> 61 #ifdef KTRACE 62 #include <sys/ktrace.h> 63 #endif 64 #ifdef INVARIANTS 65 #include <machine/_inttypes.h> 66 #endif 67 68 #include <security/audit/audit.h> 69 #include <security/mac/mac_framework.h> 70 71 #include <vm/uma.h> 72 73 #define NAMEI_DIAGNOSTIC 1 74 #undef NAMEI_DIAGNOSTIC 75 76 SDT_PROVIDER_DEFINE(vfs); 77 SDT_PROBE_DEFINE4(vfs, namei, lookup, entry, "struct vnode *", "char *", 78 "unsigned long", "bool"); 79 SDT_PROBE_DEFINE3(vfs, namei, lookup, return, "int", "struct vnode *", "bool"); 80 81 /* Allocation zone for namei. */ 82 uma_zone_t namei_zone; 83 84 /* Placeholder vnode for mp traversal. */ 85 static struct vnode *vp_crossmp; 86 87 static int 88 crossmp_vop_islocked(struct vop_islocked_args *ap) 89 { 90 91 return (LK_SHARED); 92 } 93 94 static int 95 crossmp_vop_lock1(struct vop_lock1_args *ap) 96 { 97 struct vnode *vp; 98 struct lock *lk __unused; 99 const char *file __unused; 100 int flags, line __unused; 101 102 vp = ap->a_vp; 103 lk = vp->v_vnlock; 104 flags = ap->a_flags; 105 file = ap->a_file; 106 line = ap->a_line; 107 108 if ((flags & LK_SHARED) == 0) 109 panic("invalid lock request for crossmp"); 110 111 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line, 112 flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL); 113 WITNESS_LOCK(&lk->lock_object, 0, file, line); 114 if ((flags & LK_INTERLOCK) != 0) 115 VI_UNLOCK(vp); 116 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line); 117 return (0); 118 } 119 120 static int 121 crossmp_vop_unlock(struct vop_unlock_args *ap) 122 { 123 struct vnode *vp; 124 struct lock *lk __unused; 125 126 vp = ap->a_vp; 127 lk = vp->v_vnlock; 128 129 WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE); 130 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE, 131 LOCK_LINE); 132 return (0); 133 } 134 135 static struct vop_vector crossmp_vnodeops = { 136 .vop_default = &default_vnodeops, 137 .vop_islocked = crossmp_vop_islocked, 138 .vop_lock1 = crossmp_vop_lock1, 139 .vop_unlock = crossmp_vop_unlock, 140 }; 141 /* 142 * VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode 143 * gets allocated early. See nameiinit for the direct call below. 144 */ 145 146 struct nameicap_tracker { 147 struct vnode *dp; 148 TAILQ_ENTRY(nameicap_tracker) nm_link; 149 }; 150 151 /* Zone for cap mode tracker elements used for dotdot capability checks. */ 152 MALLOC_DEFINE(M_NAMEITRACKER, "namei_tracker", "namei tracking for dotdot"); 153 154 static void 155 nameiinit(void *dummy __unused) 156 { 157 158 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, 159 UMA_ALIGN_PTR, 0); 160 vfs_vector_op_register(&crossmp_vnodeops); 161 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp); 162 } 163 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); 164 165 static int lookup_cap_dotdot = 1; 166 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN, 167 &lookup_cap_dotdot, 0, 168 "enables \"..\" components in path lookup in capability mode"); 169 static int lookup_cap_dotdot_nonlocal = 1; 170 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN, 171 &lookup_cap_dotdot_nonlocal, 0, 172 "enables \"..\" components in path lookup in capability mode " 173 "on non-local mount"); 174 175 static void 176 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp) 177 { 178 struct nameicap_tracker *nt; 179 struct componentname *cnp; 180 181 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR) 182 return; 183 cnp = &ndp->ni_cnd; 184 if ((cnp->cn_flags & BENEATH) != 0 && 185 (ndp->ni_lcf & NI_LCF_BENEATH_LATCHED) == 0) { 186 MPASS((ndp->ni_lcf & NI_LCF_LATCH) != 0); 187 if (dp != ndp->ni_beneath_latch) 188 return; 189 ndp->ni_lcf |= NI_LCF_BENEATH_LATCHED; 190 } 191 nt = malloc(sizeof(*nt), M_NAMEITRACKER, M_WAITOK); 192 vhold(dp); 193 nt->dp = dp; 194 TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link); 195 } 196 197 static void 198 nameicap_cleanup(struct nameidata *ndp, bool clean_latch) 199 { 200 struct nameicap_tracker *nt, *nt1; 201 202 KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) || 203 (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative")); 204 TAILQ_FOREACH_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) { 205 TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link); 206 vdrop(nt->dp); 207 free(nt, M_NAMEITRACKER); 208 } 209 if (clean_latch && (ndp->ni_lcf & NI_LCF_LATCH) != 0) { 210 ndp->ni_lcf &= ~NI_LCF_LATCH; 211 vrele(ndp->ni_beneath_latch); 212 } 213 } 214 215 /* 216 * For dotdot lookups in capability mode, only allow the component 217 * lookup to succeed if the resulting directory was already traversed 218 * during the operation. This catches situations where already 219 * traversed directory is moved to different parent, and then we walk 220 * over it with dotdots. 221 * 222 * Also allow to force failure of dotdot lookups for non-local 223 * filesystems, where external agents might assist local lookups to 224 * escape the compartment. 225 */ 226 static int 227 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp) 228 { 229 struct nameicap_tracker *nt; 230 struct mount *mp; 231 232 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL || 233 dp->v_type != VDIR) 234 return (0); 235 mp = dp->v_mount; 236 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL && 237 (mp->mnt_flag & MNT_LOCAL) == 0) 238 return (ENOTCAPABLE); 239 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head, 240 nm_link) { 241 if ((ndp->ni_lcf & NI_LCF_LATCH) != 0 && 242 ndp->ni_beneath_latch == nt->dp) { 243 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED; 244 nameicap_cleanup(ndp, false); 245 return (0); 246 } 247 if (dp == nt->dp) 248 return (0); 249 } 250 return (ENOTCAPABLE); 251 } 252 253 static void 254 namei_cleanup_cnp(struct componentname *cnp) 255 { 256 257 uma_zfree(namei_zone, cnp->cn_pnbuf); 258 #ifdef DIAGNOSTIC 259 cnp->cn_pnbuf = NULL; 260 cnp->cn_nameptr = NULL; 261 #endif 262 } 263 264 static int 265 namei_handle_root(struct nameidata *ndp, struct vnode **dpp) 266 { 267 struct componentname *cnp; 268 269 cnp = &ndp->ni_cnd; 270 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) { 271 #ifdef KTRACE 272 if (KTRPOINT(curthread, KTR_CAPFAIL)) 273 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 274 #endif 275 return (ENOTCAPABLE); 276 } 277 if ((cnp->cn_flags & BENEATH) != 0) { 278 ndp->ni_lcf |= NI_LCF_BENEATH_ABS; 279 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED; 280 nameicap_cleanup(ndp, false); 281 } 282 while (*(cnp->cn_nameptr) == '/') { 283 cnp->cn_nameptr++; 284 ndp->ni_pathlen--; 285 } 286 *dpp = ndp->ni_rootdir; 287 vrefact(*dpp); 288 return (0); 289 } 290 291 static int 292 namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp) 293 { 294 struct componentname *cnp; 295 struct file *dfp; 296 struct thread *td; 297 struct pwd *pwd; 298 cap_rights_t rights; 299 struct filecaps dirfd_caps; 300 int error; 301 bool startdir_used; 302 303 cnp = &ndp->ni_cnd; 304 td = cnp->cn_thread; 305 306 startdir_used = false; 307 *pwdp = NULL; 308 *dpp = NULL; 309 310 #ifdef CAPABILITY_MODE 311 /* 312 * In capability mode, lookups must be restricted to happen in 313 * the subtree with the root specified by the file descriptor: 314 * - The root must be real file descriptor, not the pseudo-descriptor 315 * AT_FDCWD. 316 * - The passed path must be relative and not absolute. 317 * - If lookup_cap_dotdot is disabled, path must not contain the 318 * '..' components. 319 * - If lookup_cap_dotdot is enabled, we verify that all '..' 320 * components lookups result in the directories which were 321 * previously walked by us, which prevents an escape from 322 * the relative root. 323 */ 324 if (IN_CAPABILITY_MODE(td) && (cnp->cn_flags & NOCAPCHECK) == 0) { 325 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; 326 ndp->ni_resflags |= NIRES_STRICTREL; 327 if (ndp->ni_dirfd == AT_FDCWD) { 328 #ifdef KTRACE 329 if (KTRPOINT(td, KTR_CAPFAIL)) 330 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 331 #endif 332 return (ECAPMODE); 333 } 334 } 335 #endif 336 error = 0; 337 338 /* 339 * Get starting point for the translation. 340 */ 341 pwd = pwd_hold(td); 342 /* 343 * The reference on ni_rootdir is acquired in the block below to avoid 344 * back-to-back atomics for absolute lookups. 345 */ 346 ndp->ni_rootdir = pwd->pwd_rdir; 347 ndp->ni_topdir = pwd->pwd_jdir; 348 349 if (cnp->cn_pnbuf[0] == '/') { 350 ndp->ni_resflags |= NIRES_ABS; 351 error = namei_handle_root(ndp, dpp); 352 } else { 353 if (ndp->ni_startdir != NULL) { 354 *dpp = ndp->ni_startdir; 355 startdir_used = true; 356 } else if (ndp->ni_dirfd == AT_FDCWD) { 357 *dpp = pwd->pwd_cdir; 358 vrefact(*dpp); 359 } else { 360 rights = *ndp->ni_rightsneeded; 361 cap_rights_set_one(&rights, CAP_LOOKUP); 362 363 if (cnp->cn_flags & AUDITVNODE1) 364 AUDIT_ARG_ATFD1(ndp->ni_dirfd); 365 if (cnp->cn_flags & AUDITVNODE2) 366 AUDIT_ARG_ATFD2(ndp->ni_dirfd); 367 /* 368 * Effectively inlined fgetvp_rights, because we need to 369 * inspect the file as well as grabbing the vnode. 370 */ 371 error = fget_cap(td, ndp->ni_dirfd, &rights, 372 &dfp, &ndp->ni_filecaps); 373 if (error != 0) { 374 /* 375 * Preserve the error; it should either be EBADF 376 * or capability-related, both of which can be 377 * safely returned to the caller. 378 */ 379 } else { 380 if (dfp->f_ops == &badfileops) { 381 error = EBADF; 382 } else if (dfp->f_vnode == NULL) { 383 error = ENOTDIR; 384 } else { 385 *dpp = dfp->f_vnode; 386 vrefact(*dpp); 387 388 if ((dfp->f_flag & FSEARCH) != 0) 389 cnp->cn_flags |= NOEXECCHECK; 390 } 391 fdrop(dfp, td); 392 } 393 #ifdef CAPABILITIES 394 /* 395 * If file descriptor doesn't have all rights, 396 * all lookups relative to it must also be 397 * strictly relative. 398 */ 399 CAP_ALL(&rights); 400 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights, 401 &rights) || 402 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL || 403 ndp->ni_filecaps.fc_nioctls != -1) { 404 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; 405 ndp->ni_resflags |= NIRES_STRICTREL; 406 } 407 #endif 408 } 409 if (error == 0 && (*dpp)->v_type != VDIR) 410 error = ENOTDIR; 411 } 412 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) { 413 if (ndp->ni_dirfd == AT_FDCWD) { 414 ndp->ni_beneath_latch = pwd->pwd_cdir; 415 vrefact(ndp->ni_beneath_latch); 416 } else { 417 rights = *ndp->ni_rightsneeded; 418 cap_rights_set_one(&rights, CAP_LOOKUP); 419 error = fgetvp_rights(td, ndp->ni_dirfd, &rights, 420 &dirfd_caps, &ndp->ni_beneath_latch); 421 if (error == 0 && (*dpp)->v_type != VDIR) { 422 vrele(ndp->ni_beneath_latch); 423 error = ENOTDIR; 424 } 425 } 426 if (error == 0) 427 ndp->ni_lcf |= NI_LCF_LATCH; 428 } 429 if (error == 0 && (cnp->cn_flags & RBENEATH) != 0) { 430 if (cnp->cn_pnbuf[0] == '/' || 431 (ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) { 432 error = EINVAL; 433 } else if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0) { 434 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE | 435 NI_LCF_CAP_DOTDOT; 436 } 437 } 438 439 /* 440 * If we are auditing the kernel pathname, save the user pathname. 441 */ 442 if (cnp->cn_flags & AUDITVNODE1) 443 AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf); 444 if (cnp->cn_flags & AUDITVNODE2) 445 AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf); 446 if (ndp->ni_startdir != NULL && !startdir_used) 447 vrele(ndp->ni_startdir); 448 if (error != 0) { 449 if (*dpp != NULL) 450 vrele(*dpp); 451 pwd_drop(pwd); 452 return (error); 453 } 454 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) != 455 NI_LCF_BENEATH_ABS); 456 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 && 457 lookup_cap_dotdot != 0) || 458 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 && 459 (cnp->cn_flags & BENEATH) != 0)) 460 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT; 461 SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf, 462 cnp->cn_flags, false); 463 *pwdp = pwd; 464 return (0); 465 } 466 467 static int 468 namei_getpath(struct nameidata *ndp) 469 { 470 struct componentname *cnp; 471 int error; 472 473 cnp = &ndp->ni_cnd; 474 475 /* 476 * Get a buffer for the name to be translated, and copy the 477 * name into the buffer. 478 */ 479 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); 480 if (ndp->ni_segflg == UIO_SYSSPACE) { 481 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, 482 &ndp->ni_pathlen); 483 } else { 484 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, 485 &ndp->ni_pathlen); 486 } 487 488 if (__predict_false(error != 0)) { 489 namei_cleanup_cnp(cnp); 490 return (error); 491 } 492 493 /* 494 * Don't allow empty pathnames. 495 */ 496 if (__predict_false(*cnp->cn_pnbuf == '\0')) { 497 namei_cleanup_cnp(cnp); 498 return (ENOENT); 499 } 500 501 cnp->cn_nameptr = cnp->cn_pnbuf; 502 return (0); 503 } 504 505 /* 506 * Convert a pathname into a pointer to a locked vnode. 507 * 508 * The FOLLOW flag is set when symbolic links are to be followed 509 * when they occur at the end of the name translation process. 510 * Symbolic links are always followed for all other pathname 511 * components other than the last. 512 * 513 * The segflg defines whether the name is to be copied from user 514 * space or kernel space. 515 * 516 * Overall outline of namei: 517 * 518 * copy in name 519 * get starting directory 520 * while (!done && !error) { 521 * call lookup to search path. 522 * if symbolic link, massage name in buffer and continue 523 * } 524 */ 525 int 526 namei(struct nameidata *ndp) 527 { 528 char *cp; /* pointer into pathname argument */ 529 struct vnode *dp; /* the directory we are searching */ 530 struct iovec aiov; /* uio for reading symbolic links */ 531 struct componentname *cnp; 532 struct thread *td; 533 struct pwd *pwd; 534 struct uio auio; 535 int error, linklen; 536 enum cache_fpl_status status; 537 538 cnp = &ndp->ni_cnd; 539 td = cnp->cn_thread; 540 #ifdef INVARIANTS 541 KASSERT((ndp->ni_debugflags & NAMEI_DBG_CALLED) == 0, 542 ("%s: repeated call to namei without NDREINIT", __func__)); 543 KASSERT(ndp->ni_debugflags == NAMEI_DBG_INITED, 544 ("%s: bad debugflags %d", __func__, ndp->ni_debugflags)); 545 ndp->ni_debugflags |= NAMEI_DBG_CALLED; 546 if (ndp->ni_startdir != NULL) 547 ndp->ni_debugflags |= NAMEI_DBG_HADSTARTDIR; 548 if (cnp->cn_flags & FAILIFEXISTS) { 549 KASSERT(cnp->cn_nameiop == CREATE, 550 ("%s: FAILIFEXISTS passed for op %d", __func__, cnp->cn_nameiop)); 551 /* 552 * The limitation below is to restrict hairy corner cases. 553 */ 554 KASSERT((cnp->cn_flags & (LOCKPARENT | LOCKLEAF)) == LOCKPARENT, 555 ("%s: FAILIFEXISTS must be passed with LOCKPARENT and without LOCKLEAF", 556 __func__)); 557 } 558 /* 559 * For NDVALIDATE. 560 * 561 * While NDINIT may seem like a more natural place to do it, there are 562 * callers which directly modify flags past invoking init. 563 */ 564 cnp->cn_origflags = cnp->cn_flags; 565 #endif 566 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; 567 KASSERT(ndp->ni_resflags == 0, ("%s: garbage in ni_resflags: %x\n", 568 __func__, ndp->ni_resflags)); 569 KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc")); 570 KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0, 571 ("namei: unexpected flags: %" PRIx64 "\n", 572 cnp->cn_flags & NAMEI_INTERNAL_FLAGS)); 573 if (cnp->cn_flags & NOCACHE) 574 KASSERT(cnp->cn_nameiop != LOOKUP, 575 ("%s: NOCACHE passed with LOOKUP", __func__)); 576 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR || 577 ndp->ni_startdir->v_type == VBAD); 578 579 ndp->ni_lcf = 0; 580 ndp->ni_vp = NULL; 581 582 error = namei_getpath(ndp); 583 if (__predict_false(error != 0)) { 584 return (error); 585 } 586 587 #ifdef KTRACE 588 if (KTRPOINT(td, KTR_NAMEI)) { 589 KASSERT(cnp->cn_thread == curthread, 590 ("namei not using curthread")); 591 ktrnamei(cnp->cn_pnbuf); 592 } 593 #endif 594 595 /* 596 * First try looking up the target without locking any vnodes. 597 * 598 * We may need to start from scratch or pick up where it left off. 599 */ 600 error = cache_fplookup(ndp, &status, &pwd); 601 switch (status) { 602 case CACHE_FPL_STATUS_UNSET: 603 __assert_unreachable(); 604 break; 605 case CACHE_FPL_STATUS_HANDLED: 606 if (error == 0) 607 NDVALIDATE(ndp); 608 return (error); 609 case CACHE_FPL_STATUS_PARTIAL: 610 TAILQ_INIT(&ndp->ni_cap_tracker); 611 dp = ndp->ni_startdir; 612 break; 613 case CACHE_FPL_STATUS_ABORTED: 614 TAILQ_INIT(&ndp->ni_cap_tracker); 615 error = namei_setup(ndp, &dp, &pwd); 616 if (error != 0) { 617 namei_cleanup_cnp(cnp); 618 return (error); 619 } 620 break; 621 } 622 623 ndp->ni_loopcnt = 0; 624 625 /* 626 * Locked lookup. 627 */ 628 for (;;) { 629 ndp->ni_startdir = dp; 630 error = lookup(ndp); 631 if (error != 0) { 632 /* 633 * Override an error to not allow user to use 634 * BENEATH as an oracle. 635 */ 636 if ((ndp->ni_lcf & (NI_LCF_LATCH | 637 NI_LCF_BENEATH_LATCHED)) == NI_LCF_LATCH) 638 error = ENOTCAPABLE; 639 goto out; 640 } 641 642 /* 643 * If not a symbolic link, we're done. 644 */ 645 if ((cnp->cn_flags & ISSYMLINK) == 0) { 646 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 647 namei_cleanup_cnp(cnp); 648 } else 649 cnp->cn_flags |= HASBUF; 650 if ((ndp->ni_lcf & (NI_LCF_LATCH | 651 NI_LCF_BENEATH_LATCHED)) == NI_LCF_LATCH) { 652 NDFREE(ndp, 0); 653 error = ENOTCAPABLE; 654 } 655 nameicap_cleanup(ndp, true); 656 SDT_PROBE3(vfs, namei, lookup, return, error, 657 (error == 0 ? ndp->ni_vp : NULL), false); 658 pwd_drop(pwd); 659 if (error == 0) 660 NDVALIDATE(ndp); 661 return (error); 662 } 663 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 664 error = ELOOP; 665 break; 666 } 667 #ifdef MAC 668 if ((cnp->cn_flags & NOMACCHECK) == 0) { 669 error = mac_vnode_check_readlink(td->td_ucred, 670 ndp->ni_vp); 671 if (error != 0) 672 break; 673 } 674 #endif 675 if (ndp->ni_pathlen > 1) 676 cp = uma_zalloc(namei_zone, M_WAITOK); 677 else 678 cp = cnp->cn_pnbuf; 679 aiov.iov_base = cp; 680 aiov.iov_len = MAXPATHLEN; 681 auio.uio_iov = &aiov; 682 auio.uio_iovcnt = 1; 683 auio.uio_offset = 0; 684 auio.uio_rw = UIO_READ; 685 auio.uio_segflg = UIO_SYSSPACE; 686 auio.uio_td = td; 687 auio.uio_resid = MAXPATHLEN; 688 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 689 if (error != 0) { 690 if (ndp->ni_pathlen > 1) 691 uma_zfree(namei_zone, cp); 692 break; 693 } 694 linklen = MAXPATHLEN - auio.uio_resid; 695 if (linklen == 0) { 696 if (ndp->ni_pathlen > 1) 697 uma_zfree(namei_zone, cp); 698 error = ENOENT; 699 break; 700 } 701 if (linklen + ndp->ni_pathlen > MAXPATHLEN) { 702 if (ndp->ni_pathlen > 1) 703 uma_zfree(namei_zone, cp); 704 error = ENAMETOOLONG; 705 break; 706 } 707 if (ndp->ni_pathlen > 1) { 708 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 709 uma_zfree(namei_zone, cnp->cn_pnbuf); 710 cnp->cn_pnbuf = cp; 711 } else 712 cnp->cn_pnbuf[linklen] = '\0'; 713 ndp->ni_pathlen += linklen; 714 vput(ndp->ni_vp); 715 dp = ndp->ni_dvp; 716 /* 717 * Check if root directory should replace current directory. 718 */ 719 cnp->cn_nameptr = cnp->cn_pnbuf; 720 if (*(cnp->cn_nameptr) == '/') { 721 vrele(dp); 722 error = namei_handle_root(ndp, &dp); 723 if (error != 0) 724 goto out; 725 } 726 } 727 vput(ndp->ni_vp); 728 ndp->ni_vp = NULL; 729 vrele(ndp->ni_dvp); 730 out: 731 MPASS(error != 0); 732 namei_cleanup_cnp(cnp); 733 nameicap_cleanup(ndp, true); 734 SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false); 735 pwd_drop(pwd); 736 return (error); 737 } 738 739 static int 740 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags) 741 { 742 743 if (mp == NULL || ((lkflags & LK_SHARED) && 744 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) || 745 ((cnflags & ISDOTDOT) && 746 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) { 747 lkflags &= ~LK_SHARED; 748 lkflags |= LK_EXCLUSIVE; 749 } 750 lkflags |= LK_NODDLKTREAT; 751 return (lkflags); 752 } 753 754 static __inline int 755 needs_exclusive_leaf(struct mount *mp, int flags) 756 { 757 758 /* 759 * Intermediate nodes can use shared locks, we only need to 760 * force an exclusive lock for leaf nodes. 761 */ 762 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) 763 return (0); 764 765 /* Always use exclusive locks if LOCKSHARED isn't set. */ 766 if (!(flags & LOCKSHARED)) 767 return (1); 768 769 /* 770 * For lookups during open(), if the mount point supports 771 * extended shared operations, then use a shared lock for the 772 * leaf node, otherwise use an exclusive lock. 773 */ 774 if ((flags & ISOPEN) != 0) 775 return (!MNT_EXTENDED_SHARED(mp)); 776 777 /* 778 * Lookup requests outside of open() that specify LOCKSHARED 779 * only need a shared lock on the leaf vnode. 780 */ 781 return (0); 782 } 783 784 /* 785 * Search a pathname. 786 * This is a very central and rather complicated routine. 787 * 788 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 789 * The starting directory is taken from ni_startdir. The pathname is 790 * descended until done, or a symbolic link is encountered. The variable 791 * ni_more is clear if the path is completed; it is set to one if a 792 * symbolic link needing interpretation is encountered. 793 * 794 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 795 * whether the name is to be looked up, created, renamed, or deleted. 796 * When CREATE, RENAME, or DELETE is specified, information usable in 797 * creating, renaming, or deleting a directory entry may be calculated. 798 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 799 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 800 * returned unlocked. Otherwise the parent directory is not returned. If 801 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 802 * the target is returned locked, otherwise it is returned unlocked. 803 * When creating or renaming and LOCKPARENT is specified, the target may not 804 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 805 * 806 * Overall outline of lookup: 807 * 808 * dirloop: 809 * identify next component of name at ndp->ni_ptr 810 * handle degenerate case where name is null string 811 * if .. and crossing mount points and on mounted filesys, find parent 812 * call VOP_LOOKUP routine for next component name 813 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 814 * component vnode returned in ni_vp (if it exists), locked. 815 * if result vnode is mounted on and crossing mount points, 816 * find mounted on vnode 817 * if more components of name, do next level at dirloop 818 * return the answer in ni_vp, locked if LOCKLEAF set 819 * if LOCKPARENT set, return locked parent in ni_dvp 820 * if WANTPARENT set, return unlocked parent in ni_dvp 821 */ 822 int 823 lookup(struct nameidata *ndp) 824 { 825 char *cp; /* pointer into pathname argument */ 826 char *prev_ni_next; /* saved ndp->ni_next */ 827 struct vnode *dp = NULL; /* the directory we are searching */ 828 struct vnode *tdp; /* saved dp */ 829 struct mount *mp; /* mount table entry */ 830 struct prison *pr; 831 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */ 832 int docache; /* == 0 do not cache last component */ 833 int wantparent; /* 1 => wantparent or lockparent flag */ 834 int rdonly; /* lookup read-only flag bit */ 835 int error = 0; 836 int dpunlocked = 0; /* dp has already been unlocked */ 837 int relookup = 0; /* do not consume the path component */ 838 struct componentname *cnp = &ndp->ni_cnd; 839 int lkflags_save; 840 int ni_dvp_unlocked; 841 842 /* 843 * Setup: break out flag bits into variables. 844 */ 845 ni_dvp_unlocked = 0; 846 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 847 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 848 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 849 /* 850 * When set to zero, docache causes the last component of the 851 * pathname to be deleted from the cache and the full lookup 852 * of the name to be done (via VOP_CACHEDLOOKUP()). Often 853 * filesystems need some pre-computed values that are made 854 * during the full lookup, for instance UFS sets dp->i_offset. 855 * 856 * The docache variable is set to zero when requested by the 857 * NOCACHE flag and for all modifying operations except CREATE. 858 */ 859 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 860 if (cnp->cn_nameiop == DELETE || 861 (wantparent && cnp->cn_nameiop != CREATE && 862 cnp->cn_nameiop != LOOKUP)) 863 docache = 0; 864 rdonly = cnp->cn_flags & RDONLY; 865 cnp->cn_flags &= ~ISSYMLINK; 866 ndp->ni_dvp = NULL; 867 /* 868 * We use shared locks until we hit the parent of the last cn then 869 * we adjust based on the requesting flags. 870 */ 871 cnp->cn_lkflags = LK_SHARED; 872 dp = ndp->ni_startdir; 873 ndp->ni_startdir = NULLVP; 874 vn_lock(dp, 875 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY, 876 cnp->cn_flags)); 877 878 dirloop: 879 /* 880 * Search a new directory. 881 * 882 * The last component of the filename is left accessible via 883 * cnp->cn_nameptr for callers that need the name. Callers needing 884 * the name set the SAVENAME flag. When done, they assume 885 * responsibility for freeing the pathname buffer. 886 */ 887 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 888 continue; 889 cnp->cn_namelen = cp - cnp->cn_nameptr; 890 if (cnp->cn_namelen > NAME_MAX) { 891 error = ENAMETOOLONG; 892 goto bad; 893 } 894 #ifdef NAMEI_DIAGNOSTIC 895 { char c = *cp; 896 *cp = '\0'; 897 printf("{%s}: ", cnp->cn_nameptr); 898 *cp = c; } 899 #endif 900 prev_ni_pathlen = ndp->ni_pathlen; 901 ndp->ni_pathlen -= cnp->cn_namelen; 902 KASSERT(ndp->ni_pathlen <= PATH_MAX, 903 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen)); 904 prev_ni_next = ndp->ni_next; 905 ndp->ni_next = cp; 906 907 /* 908 * Replace multiple slashes by a single slash and trailing slashes 909 * by a null. This must be done before VOP_LOOKUP() because some 910 * fs's don't know about trailing slashes. Remember if there were 911 * trailing slashes to handle symlinks, existing non-directories 912 * and non-existing files that won't be directories specially later. 913 */ 914 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 915 cp++; 916 ndp->ni_pathlen--; 917 if (*cp == '\0') { 918 *ndp->ni_next = '\0'; 919 cnp->cn_flags |= TRAILINGSLASH; 920 } 921 } 922 ndp->ni_next = cp; 923 924 cnp->cn_flags |= MAKEENTRY; 925 if (*cp == '\0' && docache == 0) 926 cnp->cn_flags &= ~MAKEENTRY; 927 if (cnp->cn_namelen == 2 && 928 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 929 cnp->cn_flags |= ISDOTDOT; 930 else 931 cnp->cn_flags &= ~ISDOTDOT; 932 if (*ndp->ni_next == 0) 933 cnp->cn_flags |= ISLASTCN; 934 else 935 cnp->cn_flags &= ~ISLASTCN; 936 937 if ((cnp->cn_flags & ISLASTCN) != 0 && 938 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' && 939 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 940 error = EINVAL; 941 goto bad; 942 } 943 944 nameicap_tracker_add(ndp, dp); 945 946 /* 947 * Check for degenerate name (e.g. / or "") 948 * which is a way of talking about a directory, 949 * e.g. like "/." or ".". 950 */ 951 if (cnp->cn_nameptr[0] == '\0') { 952 if (dp->v_type != VDIR) { 953 error = ENOTDIR; 954 goto bad; 955 } 956 if (cnp->cn_nameiop != LOOKUP) { 957 error = EISDIR; 958 goto bad; 959 } 960 if (wantparent) { 961 ndp->ni_dvp = dp; 962 VREF(dp); 963 } 964 ndp->ni_vp = dp; 965 966 if (cnp->cn_flags & AUDITVNODE1) 967 AUDIT_ARG_VNODE1(dp); 968 else if (cnp->cn_flags & AUDITVNODE2) 969 AUDIT_ARG_VNODE2(dp); 970 971 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 972 VOP_UNLOCK(dp); 973 /* XXX This should probably move to the top of function. */ 974 if (cnp->cn_flags & SAVESTART) 975 panic("lookup: SAVESTART"); 976 goto success; 977 } 978 979 /* 980 * Handle "..": five special cases. 981 * 0. If doing a capability lookup and lookup_cap_dotdot is 982 * disabled, return ENOTCAPABLE. 983 * 1. Return an error if this is the last component of 984 * the name and the operation is DELETE or RENAME. 985 * 2. If at root directory (e.g. after chroot) 986 * or at absolute root directory 987 * then ignore it so can't get out. 988 * 3. If this vnode is the root of a mounted 989 * filesystem, then replace it with the 990 * vnode which was mounted on so we take the 991 * .. in the other filesystem. 992 * 4. If the vnode is the top directory of 993 * the jail or chroot, don't let them out. 994 * 5. If doing a capability lookup and lookup_cap_dotdot is 995 * enabled, return ENOTCAPABLE if the lookup would escape 996 * from the initial file descriptor directory. Checks are 997 * done by ensuring that namei() already traversed the 998 * result of dotdot lookup. 999 */ 1000 if (cnp->cn_flags & ISDOTDOT) { 1001 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT)) 1002 == NI_LCF_STRICTRELATIVE) { 1003 #ifdef KTRACE 1004 if (KTRPOINT(curthread, KTR_CAPFAIL)) 1005 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 1006 #endif 1007 error = ENOTCAPABLE; 1008 goto bad; 1009 } 1010 if ((cnp->cn_flags & ISLASTCN) != 0 && 1011 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1012 error = EINVAL; 1013 goto bad; 1014 } 1015 for (;;) { 1016 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 1017 pr = pr->pr_parent) 1018 if (dp == pr->pr_root) 1019 break; 1020 if (dp == ndp->ni_rootdir || 1021 dp == ndp->ni_topdir || 1022 dp == rootvnode || 1023 pr != NULL || 1024 ((dp->v_vflag & VV_ROOT) != 0 && 1025 (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 1026 ndp->ni_dvp = dp; 1027 ndp->ni_vp = dp; 1028 VREF(dp); 1029 goto nextname; 1030 } 1031 if ((dp->v_vflag & VV_ROOT) == 0) 1032 break; 1033 if (VN_IS_DOOMED(dp)) { /* forced unmount */ 1034 error = ENOENT; 1035 goto bad; 1036 } 1037 tdp = dp; 1038 dp = dp->v_mount->mnt_vnodecovered; 1039 VREF(dp); 1040 vput(tdp); 1041 vn_lock(dp, 1042 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 1043 LK_RETRY, ISDOTDOT)); 1044 error = nameicap_check_dotdot(ndp, dp); 1045 if (error != 0) { 1046 #ifdef KTRACE 1047 if (KTRPOINT(curthread, KTR_CAPFAIL)) 1048 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 1049 #endif 1050 goto bad; 1051 } 1052 } 1053 } 1054 1055 /* 1056 * We now have a segment name to search for, and a directory to search. 1057 */ 1058 unionlookup: 1059 #ifdef MAC 1060 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, cnp); 1061 if (error) 1062 goto bad; 1063 #endif 1064 ndp->ni_dvp = dp; 1065 ndp->ni_vp = NULL; 1066 ASSERT_VOP_LOCKED(dp, "lookup"); 1067 /* 1068 * If we have a shared lock we may need to upgrade the lock for the 1069 * last operation. 1070 */ 1071 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) && 1072 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED) 1073 vn_lock(dp, LK_UPGRADE|LK_RETRY); 1074 if (VN_IS_DOOMED(dp)) { 1075 error = ENOENT; 1076 goto bad; 1077 } 1078 /* 1079 * If we're looking up the last component and we need an exclusive 1080 * lock, adjust our lkflags. 1081 */ 1082 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) 1083 cnp->cn_lkflags = LK_EXCLUSIVE; 1084 #ifdef NAMEI_DIAGNOSTIC 1085 vn_printf(dp, "lookup in "); 1086 #endif 1087 lkflags_save = cnp->cn_lkflags; 1088 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags, 1089 cnp->cn_flags); 1090 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp); 1091 cnp->cn_lkflags = lkflags_save; 1092 if (error != 0) { 1093 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 1094 #ifdef NAMEI_DIAGNOSTIC 1095 printf("not found\n"); 1096 #endif 1097 if ((error == ENOENT) && 1098 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 1099 (dp->v_mount->mnt_flag & MNT_UNION)) { 1100 tdp = dp; 1101 dp = dp->v_mount->mnt_vnodecovered; 1102 VREF(dp); 1103 vput(tdp); 1104 vn_lock(dp, 1105 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 1106 LK_RETRY, cnp->cn_flags)); 1107 nameicap_tracker_add(ndp, dp); 1108 goto unionlookup; 1109 } 1110 1111 if (error == ERELOOKUP) { 1112 vref(dp); 1113 ndp->ni_vp = dp; 1114 error = 0; 1115 relookup = 1; 1116 goto good; 1117 } 1118 1119 if (error != EJUSTRETURN) 1120 goto bad; 1121 /* 1122 * At this point, we know we're at the end of the 1123 * pathname. If creating / renaming, we can consider 1124 * allowing the file or directory to be created / renamed, 1125 * provided we're not on a read-only filesystem. 1126 */ 1127 if (rdonly) { 1128 error = EROFS; 1129 goto bad; 1130 } 1131 /* trailing slash only allowed for directories */ 1132 if ((cnp->cn_flags & TRAILINGSLASH) && 1133 !(cnp->cn_flags & WILLBEDIR)) { 1134 error = ENOENT; 1135 goto bad; 1136 } 1137 if ((cnp->cn_flags & LOCKPARENT) == 0) 1138 VOP_UNLOCK(dp); 1139 /* 1140 * We return with ni_vp NULL to indicate that the entry 1141 * doesn't currently exist, leaving a pointer to the 1142 * (possibly locked) directory vnode in ndp->ni_dvp. 1143 */ 1144 if (cnp->cn_flags & SAVESTART) { 1145 ndp->ni_startdir = ndp->ni_dvp; 1146 VREF(ndp->ni_startdir); 1147 } 1148 goto success; 1149 } 1150 1151 good: 1152 #ifdef NAMEI_DIAGNOSTIC 1153 printf("found\n"); 1154 #endif 1155 dp = ndp->ni_vp; 1156 1157 /* 1158 * Check to see if the vnode has been mounted on; 1159 * if so find the root of the mounted filesystem. 1160 */ 1161 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 1162 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 1163 if (vfs_busy(mp, 0)) 1164 continue; 1165 vput(dp); 1166 if (dp != ndp->ni_dvp) 1167 vput(ndp->ni_dvp); 1168 else 1169 vrele(ndp->ni_dvp); 1170 vrefact(vp_crossmp); 1171 ndp->ni_dvp = vp_crossmp; 1172 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags, 1173 cnp->cn_flags), &tdp); 1174 vfs_unbusy(mp); 1175 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) 1176 panic("vp_crossmp exclusively locked or reclaimed"); 1177 if (error) { 1178 dpunlocked = 1; 1179 goto bad2; 1180 } 1181 ndp->ni_vp = dp = tdp; 1182 } 1183 1184 /* 1185 * Check for symbolic link 1186 */ 1187 if ((dp->v_type == VLNK) && 1188 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) || 1189 *ndp->ni_next == '/')) { 1190 cnp->cn_flags |= ISSYMLINK; 1191 if (VN_IS_DOOMED(dp)) { 1192 /* 1193 * We can't know whether the directory was mounted with 1194 * NOSYMFOLLOW, so we can't follow safely. 1195 */ 1196 error = ENOENT; 1197 goto bad2; 1198 } 1199 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 1200 error = EACCES; 1201 goto bad2; 1202 } 1203 /* 1204 * Symlink code always expects an unlocked dvp. 1205 */ 1206 if (ndp->ni_dvp != ndp->ni_vp) { 1207 VOP_UNLOCK(ndp->ni_dvp); 1208 ni_dvp_unlocked = 1; 1209 } 1210 goto success; 1211 } 1212 1213 nextname: 1214 /* 1215 * Not a symbolic link that we will follow. Continue with the 1216 * next component if there is any; otherwise, we're done. 1217 */ 1218 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 1219 ("lookup: invalid path state.")); 1220 if (relookup) { 1221 relookup = 0; 1222 ndp->ni_pathlen = prev_ni_pathlen; 1223 ndp->ni_next = prev_ni_next; 1224 if (ndp->ni_dvp != dp) 1225 vput(ndp->ni_dvp); 1226 else 1227 vrele(ndp->ni_dvp); 1228 goto dirloop; 1229 } 1230 if (cnp->cn_flags & ISDOTDOT) { 1231 error = nameicap_check_dotdot(ndp, ndp->ni_vp); 1232 if (error != 0) { 1233 #ifdef KTRACE 1234 if (KTRPOINT(curthread, KTR_CAPFAIL)) 1235 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 1236 #endif 1237 goto bad2; 1238 } 1239 } 1240 if (*ndp->ni_next == '/') { 1241 cnp->cn_nameptr = ndp->ni_next; 1242 while (*cnp->cn_nameptr == '/') { 1243 cnp->cn_nameptr++; 1244 ndp->ni_pathlen--; 1245 } 1246 if (ndp->ni_dvp != dp) 1247 vput(ndp->ni_dvp); 1248 else 1249 vrele(ndp->ni_dvp); 1250 goto dirloop; 1251 } 1252 /* 1253 * If we're processing a path with a trailing slash, 1254 * check that the end result is a directory. 1255 */ 1256 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) { 1257 error = ENOTDIR; 1258 goto bad2; 1259 } 1260 /* 1261 * Disallow directory write attempts on read-only filesystems. 1262 */ 1263 if (rdonly && 1264 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1265 error = EROFS; 1266 goto bad2; 1267 } 1268 if (cnp->cn_flags & SAVESTART) { 1269 ndp->ni_startdir = ndp->ni_dvp; 1270 VREF(ndp->ni_startdir); 1271 } 1272 if (!wantparent) { 1273 ni_dvp_unlocked = 2; 1274 if (ndp->ni_dvp != dp) 1275 vput(ndp->ni_dvp); 1276 else 1277 vrele(ndp->ni_dvp); 1278 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { 1279 VOP_UNLOCK(ndp->ni_dvp); 1280 ni_dvp_unlocked = 1; 1281 } 1282 1283 if (cnp->cn_flags & AUDITVNODE1) 1284 AUDIT_ARG_VNODE1(dp); 1285 else if (cnp->cn_flags & AUDITVNODE2) 1286 AUDIT_ARG_VNODE2(dp); 1287 1288 if ((cnp->cn_flags & LOCKLEAF) == 0) 1289 VOP_UNLOCK(dp); 1290 success: 1291 /* 1292 * FIXME: for lookups which only cross a mount point to fetch the 1293 * root vnode, ni_dvp will be set to vp_crossmp. This can be a problem 1294 * if either WANTPARENT or LOCKPARENT is set. 1295 */ 1296 /* 1297 * Because of shared lookup we may have the vnode shared locked, but 1298 * the caller may want it to be exclusively locked. 1299 */ 1300 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && 1301 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { 1302 vn_lock(dp, LK_UPGRADE | LK_RETRY); 1303 if (VN_IS_DOOMED(dp)) { 1304 error = ENOENT; 1305 goto bad2; 1306 } 1307 } 1308 if (ndp->ni_vp != NULL) { 1309 nameicap_tracker_add(ndp, ndp->ni_vp); 1310 if ((cnp->cn_flags & (FAILIFEXISTS | ISSYMLINK)) == FAILIFEXISTS) 1311 goto bad_eexist; 1312 } 1313 return (0); 1314 1315 bad2: 1316 if (ni_dvp_unlocked != 2) { 1317 if (dp != ndp->ni_dvp && !ni_dvp_unlocked) 1318 vput(ndp->ni_dvp); 1319 else 1320 vrele(ndp->ni_dvp); 1321 } 1322 bad: 1323 if (!dpunlocked) 1324 vput(dp); 1325 ndp->ni_vp = NULL; 1326 return (error); 1327 bad_eexist: 1328 /* 1329 * FAILIFEXISTS handling. 1330 * 1331 * XXX namei called with LOCKPARENT but not LOCKLEAF has the strange 1332 * behaviour of leaving the vnode unlocked if the target is the same 1333 * vnode as the parent. 1334 */ 1335 MPASS((cnp->cn_flags & ISSYMLINK) == 0); 1336 if (ndp->ni_vp == ndp->ni_dvp) 1337 vrele(ndp->ni_dvp); 1338 else 1339 vput(ndp->ni_dvp); 1340 vrele(ndp->ni_vp); 1341 ndp->ni_dvp = NULL; 1342 ndp->ni_vp = NULL; 1343 NDFREE(ndp, NDF_ONLY_PNBUF); 1344 return (EEXIST); 1345 } 1346 1347 /* 1348 * relookup - lookup a path name component 1349 * Used by lookup to re-acquire things. 1350 */ 1351 int 1352 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 1353 { 1354 struct vnode *dp = NULL; /* the directory we are searching */ 1355 int rdonly; /* lookup read-only flag bit */ 1356 int error = 0; 1357 1358 KASSERT(cnp->cn_flags & ISLASTCN, 1359 ("relookup: Not given last component.")); 1360 /* 1361 * Setup: break out flag bits into variables. 1362 */ 1363 KASSERT((cnp->cn_flags & (LOCKPARENT | WANTPARENT)) != 0, 1364 ("relookup: parent not wanted")); 1365 rdonly = cnp->cn_flags & RDONLY; 1366 cnp->cn_flags &= ~ISSYMLINK; 1367 dp = dvp; 1368 cnp->cn_lkflags = LK_EXCLUSIVE; 1369 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 1370 1371 /* 1372 * Search a new directory. 1373 * 1374 * The last component of the filename is left accessible via 1375 * cnp->cn_nameptr for callers that need the name. Callers needing 1376 * the name set the SAVENAME flag. When done, they assume 1377 * responsibility for freeing the pathname buffer. 1378 */ 1379 #ifdef NAMEI_DIAGNOSTIC 1380 printf("{%s}: ", cnp->cn_nameptr); 1381 #endif 1382 1383 /* 1384 * Check for "" which represents the root directory after slash 1385 * removal. 1386 */ 1387 if (cnp->cn_nameptr[0] == '\0') { 1388 /* 1389 * Support only LOOKUP for "/" because lookup() 1390 * can't succeed for CREATE, DELETE and RENAME. 1391 */ 1392 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP")); 1393 KASSERT(dp->v_type == VDIR, ("dp is not a directory")); 1394 1395 if (!(cnp->cn_flags & LOCKLEAF)) 1396 VOP_UNLOCK(dp); 1397 *vpp = dp; 1398 /* XXX This should probably move to the top of function. */ 1399 if (cnp->cn_flags & SAVESTART) 1400 panic("lookup: SAVESTART"); 1401 return (0); 1402 } 1403 1404 if (cnp->cn_flags & ISDOTDOT) 1405 panic ("relookup: lookup on dot-dot"); 1406 1407 /* 1408 * We now have a segment name to search for, and a directory to search. 1409 */ 1410 #ifdef NAMEI_DIAGNOSTIC 1411 vn_printf(dp, "search in "); 1412 #endif 1413 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 1414 KASSERT(*vpp == NULL, ("leaf should be empty")); 1415 if (error != EJUSTRETURN) 1416 goto bad; 1417 /* 1418 * If creating and at end of pathname, then can consider 1419 * allowing file to be created. 1420 */ 1421 if (rdonly) { 1422 error = EROFS; 1423 goto bad; 1424 } 1425 /* ASSERT(dvp == ndp->ni_startdir) */ 1426 if (cnp->cn_flags & SAVESTART) 1427 VREF(dvp); 1428 if ((cnp->cn_flags & LOCKPARENT) == 0) 1429 VOP_UNLOCK(dp); 1430 /* 1431 * We return with ni_vp NULL to indicate that the entry 1432 * doesn't currently exist, leaving a pointer to the 1433 * (possibly locked) directory vnode in ndp->ni_dvp. 1434 */ 1435 return (0); 1436 } 1437 1438 dp = *vpp; 1439 1440 /* 1441 * Disallow directory write attempts on read-only filesystems. 1442 */ 1443 if (rdonly && 1444 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1445 if (dvp == dp) 1446 vrele(dvp); 1447 else 1448 vput(dvp); 1449 error = EROFS; 1450 goto bad; 1451 } 1452 /* 1453 * Set the parent lock/ref state to the requested state. 1454 */ 1455 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) 1456 VOP_UNLOCK(dvp); 1457 /* 1458 * Check for symbolic link 1459 */ 1460 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 1461 ("relookup: symlink found.\n")); 1462 1463 /* ASSERT(dvp == ndp->ni_startdir) */ 1464 if (cnp->cn_flags & SAVESTART) 1465 VREF(dvp); 1466 1467 if ((cnp->cn_flags & LOCKLEAF) == 0) 1468 VOP_UNLOCK(dp); 1469 return (0); 1470 bad: 1471 vput(dp); 1472 *vpp = NULL; 1473 return (error); 1474 } 1475 1476 /* 1477 * Free data allocated by namei(); see namei(9) for details. 1478 */ 1479 void 1480 NDFREE_PNBUF(struct nameidata *ndp) 1481 { 1482 1483 if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) { 1484 MPASS((ndp->ni_cnd.cn_flags & (SAVENAME | SAVESTART)) != 0); 1485 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 1486 ndp->ni_cnd.cn_flags &= ~HASBUF; 1487 } 1488 } 1489 1490 void 1491 (NDFREE)(struct nameidata *ndp, const u_int flags) 1492 { 1493 int unlock_dvp; 1494 int unlock_vp; 1495 1496 unlock_dvp = 0; 1497 unlock_vp = 0; 1498 1499 if (!(flags & NDF_NO_FREE_PNBUF)) { 1500 NDFREE_PNBUF(ndp); 1501 } 1502 if (!(flags & NDF_NO_VP_UNLOCK) && 1503 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 1504 unlock_vp = 1; 1505 if (!(flags & NDF_NO_DVP_UNLOCK) && 1506 (ndp->ni_cnd.cn_flags & LOCKPARENT) && 1507 ndp->ni_dvp != ndp->ni_vp) 1508 unlock_dvp = 1; 1509 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 1510 if (unlock_vp) { 1511 vput(ndp->ni_vp); 1512 unlock_vp = 0; 1513 } else 1514 vrele(ndp->ni_vp); 1515 ndp->ni_vp = NULL; 1516 } 1517 if (unlock_vp) 1518 VOP_UNLOCK(ndp->ni_vp); 1519 if (!(flags & NDF_NO_DVP_RELE) && 1520 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 1521 if (unlock_dvp) { 1522 vput(ndp->ni_dvp); 1523 unlock_dvp = 0; 1524 } else 1525 vrele(ndp->ni_dvp); 1526 ndp->ni_dvp = NULL; 1527 } 1528 if (unlock_dvp) 1529 VOP_UNLOCK(ndp->ni_dvp); 1530 if (!(flags & NDF_NO_STARTDIR_RELE) && 1531 (ndp->ni_cnd.cn_flags & SAVESTART)) { 1532 vrele(ndp->ni_startdir); 1533 ndp->ni_startdir = NULL; 1534 } 1535 } 1536 1537 #ifdef INVARIANTS 1538 /* 1539 * Validate the final state of ndp after the lookup. 1540 * 1541 * Historically filesystems were allowed to modify cn_flags. Most notably they 1542 * can add SAVENAME to the request, resulting in HASBUF and pushing subsequent 1543 * clean up to the consumer. In practice this seems to only concern != LOOKUP 1544 * operations. 1545 * 1546 * As a step towards stricter API contract this routine validates the state to 1547 * clean up. Note validation is a work in progress with the intent of becoming 1548 * stricter over time. 1549 */ 1550 #define NDMODIFYINGFLAGS (LOCKLEAF | LOCKPARENT | WANTPARENT | SAVENAME | SAVESTART | HASBUF) 1551 void 1552 NDVALIDATE(struct nameidata *ndp) 1553 { 1554 struct componentname *cnp; 1555 u_int64_t used, orig; 1556 1557 cnp = &ndp->ni_cnd; 1558 orig = cnp->cn_origflags; 1559 used = cnp->cn_flags; 1560 switch (cnp->cn_nameiop) { 1561 case LOOKUP: 1562 /* 1563 * For plain lookup we require strict conformance -- nothing 1564 * to clean up if it was not requested by the caller. 1565 */ 1566 orig &= NDMODIFYINGFLAGS; 1567 used &= NDMODIFYINGFLAGS; 1568 if ((orig & (SAVENAME | SAVESTART)) != 0) 1569 orig |= HASBUF; 1570 if (orig != used) { 1571 goto out_mismatch; 1572 } 1573 break; 1574 case CREATE: 1575 case DELETE: 1576 case RENAME: 1577 /* 1578 * Some filesystems set SAVENAME to provoke HASBUF, accomodate 1579 * for it until it gets fixed. 1580 */ 1581 orig &= NDMODIFYINGFLAGS; 1582 orig |= (SAVENAME | HASBUF); 1583 used &= NDMODIFYINGFLAGS; 1584 used |= (SAVENAME | HASBUF); 1585 if (orig != used) { 1586 goto out_mismatch; 1587 } 1588 break; 1589 } 1590 return; 1591 out_mismatch: 1592 panic("%s: mismatched flags for op %d: added %" PRIx64 ", " 1593 "removed %" PRIx64" (%" PRIx64" != %" PRIx64"; stored %" PRIx64" != %" PRIx64")", 1594 __func__, cnp->cn_nameiop, used & ~orig, orig &~ used, 1595 orig, used, cnp->cn_origflags, cnp->cn_flags); 1596 } 1597 #endif 1598 1599 /* 1600 * Determine if there is a suitable alternate filename under the specified 1601 * prefix for the specified path. If the create flag is set, then the 1602 * alternate prefix will be used so long as the parent directory exists. 1603 * This is used by the various compatibility ABIs so that Linux binaries prefer 1604 * files under /compat/linux for example. The chosen path (whether under 1605 * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1606 * to by pathbuf. The caller is responsible for free'ing the buffer from 1607 * the M_TEMP bucket if one is returned. 1608 */ 1609 int 1610 kern_alternate_path(struct thread *td, const char *prefix, const char *path, 1611 enum uio_seg pathseg, char **pathbuf, int create, int dirfd) 1612 { 1613 struct nameidata nd, ndroot; 1614 char *ptr, *buf, *cp; 1615 size_t len, sz; 1616 int error; 1617 1618 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1619 *pathbuf = buf; 1620 1621 /* Copy the prefix into the new pathname as a starting point. */ 1622 len = strlcpy(buf, prefix, MAXPATHLEN); 1623 if (len >= MAXPATHLEN) { 1624 *pathbuf = NULL; 1625 free(buf, M_TEMP); 1626 return (EINVAL); 1627 } 1628 sz = MAXPATHLEN - len; 1629 ptr = buf + len; 1630 1631 /* Append the filename to the prefix. */ 1632 if (pathseg == UIO_SYSSPACE) 1633 error = copystr(path, ptr, sz, &len); 1634 else 1635 error = copyinstr(path, ptr, sz, &len); 1636 1637 if (error) { 1638 *pathbuf = NULL; 1639 free(buf, M_TEMP); 1640 return (error); 1641 } 1642 1643 /* Only use a prefix with absolute pathnames. */ 1644 if (*ptr != '/') { 1645 error = EINVAL; 1646 goto keeporig; 1647 } 1648 1649 if (dirfd != AT_FDCWD) { 1650 /* 1651 * We want the original because the "prefix" is 1652 * included in the already opened dirfd. 1653 */ 1654 bcopy(ptr, buf, len); 1655 return (0); 1656 } 1657 1658 /* 1659 * We know that there is a / somewhere in this pathname. 1660 * Search backwards for it, to find the file's parent dir 1661 * to see if it exists in the alternate tree. If it does, 1662 * and we want to create a file (cflag is set). We don't 1663 * need to worry about the root comparison in this case. 1664 */ 1665 1666 if (create) { 1667 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1668 *cp = '\0'; 1669 1670 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td); 1671 error = namei(&nd); 1672 *cp = '/'; 1673 if (error != 0) 1674 goto keeporig; 1675 } else { 1676 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td); 1677 1678 error = namei(&nd); 1679 if (error != 0) 1680 goto keeporig; 1681 1682 /* 1683 * We now compare the vnode of the prefix to the one 1684 * vnode asked. If they resolve to be the same, then we 1685 * ignore the match so that the real root gets used. 1686 * This avoids the problem of traversing "../.." to find the 1687 * root directory and never finding it, because "/" resolves 1688 * to the emulation root directory. This is expensive :-( 1689 */ 1690 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix, 1691 td); 1692 1693 /* We shouldn't ever get an error from this namei(). */ 1694 error = namei(&ndroot); 1695 if (error == 0) { 1696 if (nd.ni_vp == ndroot.ni_vp) 1697 error = ENOENT; 1698 1699 NDFREE(&ndroot, NDF_ONLY_PNBUF); 1700 vrele(ndroot.ni_vp); 1701 } 1702 } 1703 1704 NDFREE(&nd, NDF_ONLY_PNBUF); 1705 vrele(nd.ni_vp); 1706 1707 keeporig: 1708 /* If there was an error, use the original path name. */ 1709 if (error) 1710 bcopy(ptr, buf, len); 1711 return (error); 1712 } 1713