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 static uma_zone_t nt_zone; 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 nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker), 161 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 162 vfs_vector_op_register(&crossmp_vnodeops); 163 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp); 164 } 165 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); 166 167 static int lookup_cap_dotdot = 1; 168 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN, 169 &lookup_cap_dotdot, 0, 170 "enables \"..\" components in path lookup in capability mode"); 171 static int lookup_cap_dotdot_nonlocal = 1; 172 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN, 173 &lookup_cap_dotdot_nonlocal, 0, 174 "enables \"..\" components in path lookup in capability mode " 175 "on non-local mount"); 176 177 static void 178 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp) 179 { 180 struct nameicap_tracker *nt; 181 182 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR) 183 return; 184 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_BENEATH_LATCHED)) == 185 NI_LCF_BENEATH_ABS) { 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 = uma_zalloc(nt_zone, 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 uma_zfree(nt_zone, nt); 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. Also fail dotdot lookups for non-local 219 * filesystems, where external agents might assist local lookups to 220 * escape the compartment. 221 */ 222 static int 223 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp) 224 { 225 struct nameicap_tracker *nt; 226 struct mount *mp; 227 228 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL || 229 dp->v_type != VDIR) 230 return (0); 231 mp = dp->v_mount; 232 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL && 233 (mp->mnt_flag & MNT_LOCAL) == 0) 234 return (ENOTCAPABLE); 235 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head, 236 nm_link) { 237 if (dp == nt->dp) 238 return (0); 239 } 240 if ((ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) { 241 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED; 242 nameicap_cleanup(ndp, false); 243 return (0); 244 } 245 return (ENOTCAPABLE); 246 } 247 248 static void 249 namei_cleanup_cnp(struct componentname *cnp) 250 { 251 252 uma_zfree(namei_zone, cnp->cn_pnbuf); 253 #ifdef DIAGNOSTIC 254 cnp->cn_pnbuf = NULL; 255 cnp->cn_nameptr = NULL; 256 #endif 257 } 258 259 static int 260 namei_handle_root(struct nameidata *ndp, struct vnode **dpp) 261 { 262 struct componentname *cnp; 263 264 cnp = &ndp->ni_cnd; 265 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) { 266 #ifdef KTRACE 267 if (KTRPOINT(curthread, KTR_CAPFAIL)) 268 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 269 #endif 270 return (ENOTCAPABLE); 271 } 272 if ((cnp->cn_flags & BENEATH) != 0) { 273 ndp->ni_lcf |= NI_LCF_BENEATH_ABS; 274 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED; 275 nameicap_cleanup(ndp, false); 276 } 277 while (*(cnp->cn_nameptr) == '/') { 278 cnp->cn_nameptr++; 279 ndp->ni_pathlen--; 280 } 281 *dpp = ndp->ni_rootdir; 282 vrefact(*dpp); 283 return (0); 284 } 285 286 static int 287 namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp) 288 { 289 struct componentname *cnp; 290 struct file *dfp; 291 struct thread *td; 292 struct pwd *pwd; 293 cap_rights_t rights; 294 struct filecaps dirfd_caps; 295 int error; 296 bool startdir_used; 297 298 cnp = &ndp->ni_cnd; 299 td = cnp->cn_thread; 300 301 startdir_used = false; 302 *pwdp = NULL; 303 *dpp = NULL; 304 305 #ifdef CAPABILITY_MODE 306 /* 307 * In capability mode, lookups must be restricted to happen in 308 * the subtree with the root specified by the file descriptor: 309 * - The root must be real file descriptor, not the pseudo-descriptor 310 * AT_FDCWD. 311 * - The passed path must be relative and not absolute. 312 * - If lookup_cap_dotdot is disabled, path must not contain the 313 * '..' components. 314 * - If lookup_cap_dotdot is enabled, we verify that all '..' 315 * components lookups result in the directories which were 316 * previously walked by us, which prevents an escape from 317 * the relative root. 318 */ 319 if (IN_CAPABILITY_MODE(td) && (cnp->cn_flags & NOCAPCHECK) == 0) { 320 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; 321 if (ndp->ni_dirfd == AT_FDCWD) { 322 #ifdef KTRACE 323 if (KTRPOINT(td, KTR_CAPFAIL)) 324 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 325 #endif 326 return (ECAPMODE); 327 } 328 } 329 #endif 330 error = 0; 331 332 /* 333 * Get starting point for the translation. 334 */ 335 pwd = pwd_hold(td); 336 /* 337 * The reference on ni_rootdir is acquired in the block below to avoid 338 * back-to-back atomics for absolute lookups. 339 */ 340 ndp->ni_rootdir = pwd->pwd_rdir; 341 ndp->ni_topdir = pwd->pwd_jdir; 342 343 if (cnp->cn_pnbuf[0] == '/') { 344 ndp->ni_resflags |= NIRES_ABS; 345 error = namei_handle_root(ndp, dpp); 346 } else { 347 if (ndp->ni_startdir != NULL) { 348 *dpp = ndp->ni_startdir; 349 startdir_used = true; 350 } else if (ndp->ni_dirfd == AT_FDCWD) { 351 *dpp = pwd->pwd_cdir; 352 vrefact(*dpp); 353 } else { 354 rights = *ndp->ni_rightsneeded; 355 cap_rights_set_one(&rights, CAP_LOOKUP); 356 357 if (cnp->cn_flags & AUDITVNODE1) 358 AUDIT_ARG_ATFD1(ndp->ni_dirfd); 359 if (cnp->cn_flags & AUDITVNODE2) 360 AUDIT_ARG_ATFD2(ndp->ni_dirfd); 361 /* 362 * Effectively inlined fgetvp_rights, because we need to 363 * inspect the file as well as grabbing the vnode. 364 */ 365 error = fget_cap(td, ndp->ni_dirfd, &rights, 366 &dfp, &ndp->ni_filecaps); 367 if (error != 0) { 368 /* 369 * Preserve the error; it should either be EBADF 370 * or capability-related, both of which can be 371 * safely returned to the caller. 372 */ 373 } else { 374 if (dfp->f_ops == &badfileops) { 375 error = EBADF; 376 } else if (dfp->f_vnode == NULL) { 377 error = ENOTDIR; 378 } else { 379 *dpp = dfp->f_vnode; 380 vrefact(*dpp); 381 382 if ((dfp->f_flag & FSEARCH) != 0) 383 cnp->cn_flags |= NOEXECCHECK; 384 } 385 fdrop(dfp, td); 386 } 387 #ifdef CAPABILITIES 388 /* 389 * If file descriptor doesn't have all rights, 390 * all lookups relative to it must also be 391 * strictly relative. 392 */ 393 CAP_ALL(&rights); 394 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights, 395 &rights) || 396 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL || 397 ndp->ni_filecaps.fc_nioctls != -1) { 398 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; 399 } 400 #endif 401 } 402 if (error == 0 && (*dpp)->v_type != VDIR) 403 error = ENOTDIR; 404 } 405 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) { 406 if (ndp->ni_dirfd == AT_FDCWD) { 407 ndp->ni_beneath_latch = pwd->pwd_cdir; 408 vrefact(ndp->ni_beneath_latch); 409 } else { 410 rights = *ndp->ni_rightsneeded; 411 cap_rights_set_one(&rights, CAP_LOOKUP); 412 error = fgetvp_rights(td, ndp->ni_dirfd, &rights, 413 &dirfd_caps, &ndp->ni_beneath_latch); 414 if (error == 0 && (*dpp)->v_type != VDIR) { 415 vrele(ndp->ni_beneath_latch); 416 error = ENOTDIR; 417 } 418 } 419 if (error == 0) 420 ndp->ni_lcf |= NI_LCF_LATCH; 421 } 422 /* 423 * If we are auditing the kernel pathname, save the user pathname. 424 */ 425 if (cnp->cn_flags & AUDITVNODE1) 426 AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf); 427 if (cnp->cn_flags & AUDITVNODE2) 428 AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf); 429 if (ndp->ni_startdir != NULL && !startdir_used) 430 vrele(ndp->ni_startdir); 431 if (error != 0) { 432 if (*dpp != NULL) 433 vrele(*dpp); 434 pwd_drop(pwd); 435 return (error); 436 } 437 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) != 438 NI_LCF_BENEATH_ABS); 439 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 && 440 lookup_cap_dotdot != 0) || 441 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 && 442 (cnp->cn_flags & BENEATH) != 0)) 443 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT; 444 SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf, 445 cnp->cn_flags, false); 446 *pwdp = pwd; 447 return (0); 448 } 449 450 /* 451 * Convert a pathname into a pointer to a locked vnode. 452 * 453 * The FOLLOW flag is set when symbolic links are to be followed 454 * when they occur at the end of the name translation process. 455 * Symbolic links are always followed for all other pathname 456 * components other than the last. 457 * 458 * The segflg defines whether the name is to be copied from user 459 * space or kernel space. 460 * 461 * Overall outline of namei: 462 * 463 * copy in name 464 * get starting directory 465 * while (!done && !error) { 466 * call lookup to search path. 467 * if symbolic link, massage name in buffer and continue 468 * } 469 */ 470 int 471 namei(struct nameidata *ndp) 472 { 473 char *cp; /* pointer into pathname argument */ 474 struct vnode *dp; /* the directory we are searching */ 475 struct iovec aiov; /* uio for reading symbolic links */ 476 struct componentname *cnp; 477 struct thread *td; 478 struct pwd *pwd; 479 struct uio auio; 480 int error, linklen; 481 enum cache_fpl_status status; 482 483 cnp = &ndp->ni_cnd; 484 td = cnp->cn_thread; 485 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; 486 KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc")); 487 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, 488 ("namei: nameiop contaminated with flags")); 489 KASSERT((cnp->cn_flags & OPMASK) == 0, 490 ("namei: flags contaminated with nameiops")); 491 KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0, 492 ("namei: unexpected flags: %" PRIx64 "\n", 493 cnp->cn_flags & NAMEI_INTERNAL_FLAGS)); 494 if (cnp->cn_flags & NOCACHE) 495 KASSERT(cnp->cn_nameiop != LOOKUP, 496 ("%s: NOCACHE passed with LOOKUP", __func__)); 497 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR || 498 ndp->ni_startdir->v_type == VBAD); 499 500 ndp->ni_lcf = 0; 501 ndp->ni_vp = NULL; 502 503 /* 504 * Get a buffer for the name to be translated, and copy the 505 * name into the buffer. 506 */ 507 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); 508 if (ndp->ni_segflg == UIO_SYSSPACE) 509 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, 510 &ndp->ni_pathlen); 511 else 512 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, 513 &ndp->ni_pathlen); 514 515 if (__predict_false(error != 0)) { 516 namei_cleanup_cnp(cnp); 517 return (error); 518 } 519 520 /* 521 * Don't allow empty pathnames. 522 */ 523 if (__predict_false(*cnp->cn_pnbuf == '\0')) { 524 namei_cleanup_cnp(cnp); 525 return (ENOENT); 526 } 527 528 #ifdef KTRACE 529 if (KTRPOINT(td, KTR_NAMEI)) { 530 KASSERT(cnp->cn_thread == curthread, 531 ("namei not using curthread")); 532 ktrnamei(cnp->cn_pnbuf); 533 } 534 #endif 535 536 cnp->cn_nameptr = cnp->cn_pnbuf; 537 538 /* 539 * First try looking up the target without locking any vnodes. 540 * 541 * We may need to start from scratch or pick up where it left off. 542 */ 543 error = cache_fplookup(ndp, &status, &pwd); 544 switch (status) { 545 case CACHE_FPL_STATUS_UNSET: 546 __assert_unreachable(); 547 break; 548 case CACHE_FPL_STATUS_HANDLED: 549 return (error); 550 case CACHE_FPL_STATUS_PARTIAL: 551 TAILQ_INIT(&ndp->ni_cap_tracker); 552 dp = ndp->ni_startdir; 553 break; 554 case CACHE_FPL_STATUS_ABORTED: 555 TAILQ_INIT(&ndp->ni_cap_tracker); 556 error = namei_setup(ndp, &dp, &pwd); 557 if (error != 0) { 558 namei_cleanup_cnp(cnp); 559 return (error); 560 } 561 break; 562 } 563 564 ndp->ni_loopcnt = 0; 565 566 /* 567 * Locked lookup. 568 */ 569 for (;;) { 570 ndp->ni_startdir = dp; 571 error = lookup(ndp); 572 if (error != 0) 573 goto out; 574 /* 575 * If not a symbolic link, we're done. 576 */ 577 if ((cnp->cn_flags & ISSYMLINK) == 0) { 578 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 579 namei_cleanup_cnp(cnp); 580 } else 581 cnp->cn_flags |= HASBUF; 582 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | 583 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) { 584 NDFREE(ndp, 0); 585 error = ENOTCAPABLE; 586 } 587 nameicap_cleanup(ndp, true); 588 SDT_PROBE3(vfs, namei, lookup, return, error, 589 (error == 0 ? ndp->ni_vp : NULL), false); 590 pwd_drop(pwd); 591 return (error); 592 } 593 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 594 error = ELOOP; 595 break; 596 } 597 #ifdef MAC 598 if ((cnp->cn_flags & NOMACCHECK) == 0) { 599 error = mac_vnode_check_readlink(td->td_ucred, 600 ndp->ni_vp); 601 if (error != 0) 602 break; 603 } 604 #endif 605 if (ndp->ni_pathlen > 1) 606 cp = uma_zalloc(namei_zone, M_WAITOK); 607 else 608 cp = cnp->cn_pnbuf; 609 aiov.iov_base = cp; 610 aiov.iov_len = MAXPATHLEN; 611 auio.uio_iov = &aiov; 612 auio.uio_iovcnt = 1; 613 auio.uio_offset = 0; 614 auio.uio_rw = UIO_READ; 615 auio.uio_segflg = UIO_SYSSPACE; 616 auio.uio_td = td; 617 auio.uio_resid = MAXPATHLEN; 618 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 619 if (error != 0) { 620 if (ndp->ni_pathlen > 1) 621 uma_zfree(namei_zone, cp); 622 break; 623 } 624 linklen = MAXPATHLEN - auio.uio_resid; 625 if (linklen == 0) { 626 if (ndp->ni_pathlen > 1) 627 uma_zfree(namei_zone, cp); 628 error = ENOENT; 629 break; 630 } 631 if (linklen + ndp->ni_pathlen > MAXPATHLEN) { 632 if (ndp->ni_pathlen > 1) 633 uma_zfree(namei_zone, cp); 634 error = ENAMETOOLONG; 635 break; 636 } 637 if (ndp->ni_pathlen > 1) { 638 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 639 uma_zfree(namei_zone, cnp->cn_pnbuf); 640 cnp->cn_pnbuf = cp; 641 } else 642 cnp->cn_pnbuf[linklen] = '\0'; 643 ndp->ni_pathlen += linklen; 644 vput(ndp->ni_vp); 645 dp = ndp->ni_dvp; 646 /* 647 * Check if root directory should replace current directory. 648 */ 649 cnp->cn_nameptr = cnp->cn_pnbuf; 650 if (*(cnp->cn_nameptr) == '/') { 651 vrele(dp); 652 error = namei_handle_root(ndp, &dp); 653 if (error != 0) 654 goto out; 655 } 656 } 657 vput(ndp->ni_vp); 658 ndp->ni_vp = NULL; 659 vrele(ndp->ni_dvp); 660 out: 661 MPASS(error != 0); 662 namei_cleanup_cnp(cnp); 663 nameicap_cleanup(ndp, true); 664 SDT_PROBE3(vfs, namei, lookup, return, error, NULL, false); 665 pwd_drop(pwd); 666 return (error); 667 } 668 669 static int 670 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags) 671 { 672 673 if (mp == NULL || ((lkflags & LK_SHARED) && 674 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) || 675 ((cnflags & ISDOTDOT) && 676 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) { 677 lkflags &= ~LK_SHARED; 678 lkflags |= LK_EXCLUSIVE; 679 } 680 lkflags |= LK_NODDLKTREAT; 681 return (lkflags); 682 } 683 684 static __inline int 685 needs_exclusive_leaf(struct mount *mp, int flags) 686 { 687 688 /* 689 * Intermediate nodes can use shared locks, we only need to 690 * force an exclusive lock for leaf nodes. 691 */ 692 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) 693 return (0); 694 695 /* Always use exclusive locks if LOCKSHARED isn't set. */ 696 if (!(flags & LOCKSHARED)) 697 return (1); 698 699 /* 700 * For lookups during open(), if the mount point supports 701 * extended shared operations, then use a shared lock for the 702 * leaf node, otherwise use an exclusive lock. 703 */ 704 if ((flags & ISOPEN) != 0) 705 return (!MNT_EXTENDED_SHARED(mp)); 706 707 /* 708 * Lookup requests outside of open() that specify LOCKSHARED 709 * only need a shared lock on the leaf vnode. 710 */ 711 return (0); 712 } 713 714 /* 715 * Search a pathname. 716 * This is a very central and rather complicated routine. 717 * 718 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 719 * The starting directory is taken from ni_startdir. The pathname is 720 * descended until done, or a symbolic link is encountered. The variable 721 * ni_more is clear if the path is completed; it is set to one if a 722 * symbolic link needing interpretation is encountered. 723 * 724 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 725 * whether the name is to be looked up, created, renamed, or deleted. 726 * When CREATE, RENAME, or DELETE is specified, information usable in 727 * creating, renaming, or deleting a directory entry may be calculated. 728 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 729 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 730 * returned unlocked. Otherwise the parent directory is not returned. If 731 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 732 * the target is returned locked, otherwise it is returned unlocked. 733 * When creating or renaming and LOCKPARENT is specified, the target may not 734 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 735 * 736 * Overall outline of lookup: 737 * 738 * dirloop: 739 * identify next component of name at ndp->ni_ptr 740 * handle degenerate case where name is null string 741 * if .. and crossing mount points and on mounted filesys, find parent 742 * call VOP_LOOKUP routine for next component name 743 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 744 * component vnode returned in ni_vp (if it exists), locked. 745 * if result vnode is mounted on and crossing mount points, 746 * find mounted on vnode 747 * if more components of name, do next level at dirloop 748 * return the answer in ni_vp, locked if LOCKLEAF set 749 * if LOCKPARENT set, return locked parent in ni_dvp 750 * if WANTPARENT set, return unlocked parent in ni_dvp 751 */ 752 int 753 lookup(struct nameidata *ndp) 754 { 755 char *cp; /* pointer into pathname argument */ 756 char *prev_ni_next; /* saved ndp->ni_next */ 757 struct vnode *dp = NULL; /* the directory we are searching */ 758 struct vnode *tdp; /* saved dp */ 759 struct mount *mp; /* mount table entry */ 760 struct prison *pr; 761 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */ 762 int docache; /* == 0 do not cache last component */ 763 int wantparent; /* 1 => wantparent or lockparent flag */ 764 int rdonly; /* lookup read-only flag bit */ 765 int error = 0; 766 int dpunlocked = 0; /* dp has already been unlocked */ 767 int relookup = 0; /* do not consume the path component */ 768 struct componentname *cnp = &ndp->ni_cnd; 769 int lkflags_save; 770 int ni_dvp_unlocked; 771 772 /* 773 * Setup: break out flag bits into variables. 774 */ 775 ni_dvp_unlocked = 0; 776 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 777 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 778 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 779 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 780 if (cnp->cn_nameiop == DELETE || 781 (wantparent && cnp->cn_nameiop != CREATE && 782 cnp->cn_nameiop != LOOKUP)) 783 docache = 0; 784 rdonly = cnp->cn_flags & RDONLY; 785 cnp->cn_flags &= ~ISSYMLINK; 786 ndp->ni_dvp = NULL; 787 /* 788 * We use shared locks until we hit the parent of the last cn then 789 * we adjust based on the requesting flags. 790 */ 791 cnp->cn_lkflags = LK_SHARED; 792 dp = ndp->ni_startdir; 793 ndp->ni_startdir = NULLVP; 794 vn_lock(dp, 795 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY, 796 cnp->cn_flags)); 797 798 dirloop: 799 /* 800 * Search a new directory. 801 * 802 * The last component of the filename is left accessible via 803 * cnp->cn_nameptr for callers that need the name. Callers needing 804 * the name set the SAVENAME flag. When done, they assume 805 * responsibility for freeing the pathname buffer. 806 */ 807 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 808 continue; 809 cnp->cn_namelen = cp - cnp->cn_nameptr; 810 if (cnp->cn_namelen > NAME_MAX) { 811 error = ENAMETOOLONG; 812 goto bad; 813 } 814 #ifdef NAMEI_DIAGNOSTIC 815 { char c = *cp; 816 *cp = '\0'; 817 printf("{%s}: ", cnp->cn_nameptr); 818 *cp = c; } 819 #endif 820 prev_ni_pathlen = ndp->ni_pathlen; 821 ndp->ni_pathlen -= cnp->cn_namelen; 822 KASSERT(ndp->ni_pathlen <= PATH_MAX, 823 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen)); 824 prev_ni_next = ndp->ni_next; 825 ndp->ni_next = cp; 826 827 /* 828 * Replace multiple slashes by a single slash and trailing slashes 829 * by a null. This must be done before VOP_LOOKUP() because some 830 * fs's don't know about trailing slashes. Remember if there were 831 * trailing slashes to handle symlinks, existing non-directories 832 * and non-existing files that won't be directories specially later. 833 */ 834 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 835 cp++; 836 ndp->ni_pathlen--; 837 if (*cp == '\0') { 838 *ndp->ni_next = '\0'; 839 cnp->cn_flags |= TRAILINGSLASH; 840 } 841 } 842 ndp->ni_next = cp; 843 844 cnp->cn_flags |= MAKEENTRY; 845 if (*cp == '\0' && docache == 0) 846 cnp->cn_flags &= ~MAKEENTRY; 847 if (cnp->cn_namelen == 2 && 848 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 849 cnp->cn_flags |= ISDOTDOT; 850 else 851 cnp->cn_flags &= ~ISDOTDOT; 852 if (*ndp->ni_next == 0) 853 cnp->cn_flags |= ISLASTCN; 854 else 855 cnp->cn_flags &= ~ISLASTCN; 856 857 if ((cnp->cn_flags & ISLASTCN) != 0 && 858 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' && 859 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 860 error = EINVAL; 861 goto bad; 862 } 863 864 nameicap_tracker_add(ndp, dp); 865 866 /* 867 * Check for degenerate name (e.g. / or "") 868 * which is a way of talking about a directory, 869 * e.g. like "/." or ".". 870 */ 871 if (cnp->cn_nameptr[0] == '\0') { 872 if (dp->v_type != VDIR) { 873 error = ENOTDIR; 874 goto bad; 875 } 876 if (cnp->cn_nameiop != LOOKUP) { 877 error = EISDIR; 878 goto bad; 879 } 880 if (wantparent) { 881 ndp->ni_dvp = dp; 882 VREF(dp); 883 } 884 ndp->ni_vp = dp; 885 886 if (cnp->cn_flags & AUDITVNODE1) 887 AUDIT_ARG_VNODE1(dp); 888 else if (cnp->cn_flags & AUDITVNODE2) 889 AUDIT_ARG_VNODE2(dp); 890 891 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 892 VOP_UNLOCK(dp); 893 /* XXX This should probably move to the top of function. */ 894 if (cnp->cn_flags & SAVESTART) 895 panic("lookup: SAVESTART"); 896 goto success; 897 } 898 899 /* 900 * Handle "..": five special cases. 901 * 0. If doing a capability lookup and lookup_cap_dotdot is 902 * disabled, return ENOTCAPABLE. 903 * 1. Return an error if this is the last component of 904 * the name and the operation is DELETE or RENAME. 905 * 2. If at root directory (e.g. after chroot) 906 * or at absolute root directory 907 * then ignore it so can't get out. 908 * 3. If this vnode is the root of a mounted 909 * filesystem, then replace it with the 910 * vnode which was mounted on so we take the 911 * .. in the other filesystem. 912 * 4. If the vnode is the top directory of 913 * the jail or chroot, don't let them out. 914 * 5. If doing a capability lookup and lookup_cap_dotdot is 915 * enabled, return ENOTCAPABLE if the lookup would escape 916 * from the initial file descriptor directory. Checks are 917 * done by ensuring that namei() already traversed the 918 * result of dotdot lookup. 919 */ 920 if (cnp->cn_flags & ISDOTDOT) { 921 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT)) 922 == NI_LCF_STRICTRELATIVE) { 923 #ifdef KTRACE 924 if (KTRPOINT(curthread, KTR_CAPFAIL)) 925 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 926 #endif 927 error = ENOTCAPABLE; 928 goto bad; 929 } 930 if ((cnp->cn_flags & ISLASTCN) != 0 && 931 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 932 error = EINVAL; 933 goto bad; 934 } 935 for (;;) { 936 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 937 pr = pr->pr_parent) 938 if (dp == pr->pr_root) 939 break; 940 if (dp == ndp->ni_rootdir || 941 dp == ndp->ni_topdir || 942 dp == rootvnode || 943 pr != NULL || 944 ((dp->v_vflag & VV_ROOT) != 0 && 945 (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 946 ndp->ni_dvp = dp; 947 ndp->ni_vp = dp; 948 VREF(dp); 949 goto nextname; 950 } 951 if ((dp->v_vflag & VV_ROOT) == 0) 952 break; 953 if (VN_IS_DOOMED(dp)) { /* forced unmount */ 954 error = ENOENT; 955 goto bad; 956 } 957 tdp = dp; 958 dp = dp->v_mount->mnt_vnodecovered; 959 VREF(dp); 960 vput(tdp); 961 vn_lock(dp, 962 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 963 LK_RETRY, ISDOTDOT)); 964 error = nameicap_check_dotdot(ndp, dp); 965 if (error != 0) { 966 #ifdef KTRACE 967 if (KTRPOINT(curthread, KTR_CAPFAIL)) 968 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 969 #endif 970 goto bad; 971 } 972 } 973 } 974 975 /* 976 * We now have a segment name to search for, and a directory to search. 977 */ 978 unionlookup: 979 #ifdef MAC 980 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, cnp); 981 if (error) 982 goto bad; 983 #endif 984 ndp->ni_dvp = dp; 985 ndp->ni_vp = NULL; 986 ASSERT_VOP_LOCKED(dp, "lookup"); 987 /* 988 * If we have a shared lock we may need to upgrade the lock for the 989 * last operation. 990 */ 991 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) && 992 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED) 993 vn_lock(dp, LK_UPGRADE|LK_RETRY); 994 if (VN_IS_DOOMED(dp)) { 995 error = ENOENT; 996 goto bad; 997 } 998 /* 999 * If we're looking up the last component and we need an exclusive 1000 * lock, adjust our lkflags. 1001 */ 1002 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) 1003 cnp->cn_lkflags = LK_EXCLUSIVE; 1004 #ifdef NAMEI_DIAGNOSTIC 1005 vn_printf(dp, "lookup in "); 1006 #endif 1007 lkflags_save = cnp->cn_lkflags; 1008 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags, 1009 cnp->cn_flags); 1010 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp); 1011 cnp->cn_lkflags = lkflags_save; 1012 if (error != 0) { 1013 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 1014 #ifdef NAMEI_DIAGNOSTIC 1015 printf("not found\n"); 1016 #endif 1017 if ((error == ENOENT) && 1018 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 1019 (dp->v_mount->mnt_flag & MNT_UNION)) { 1020 tdp = dp; 1021 dp = dp->v_mount->mnt_vnodecovered; 1022 VREF(dp); 1023 vput(tdp); 1024 vn_lock(dp, 1025 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 1026 LK_RETRY, cnp->cn_flags)); 1027 nameicap_tracker_add(ndp, dp); 1028 goto unionlookup; 1029 } 1030 1031 if (error == ERELOOKUP) { 1032 vref(dp); 1033 ndp->ni_vp = dp; 1034 error = 0; 1035 relookup = 1; 1036 goto good; 1037 } 1038 1039 if (error != EJUSTRETURN) 1040 goto bad; 1041 /* 1042 * At this point, we know we're at the end of the 1043 * pathname. If creating / renaming, we can consider 1044 * allowing the file or directory to be created / renamed, 1045 * provided we're not on a read-only filesystem. 1046 */ 1047 if (rdonly) { 1048 error = EROFS; 1049 goto bad; 1050 } 1051 /* trailing slash only allowed for directories */ 1052 if ((cnp->cn_flags & TRAILINGSLASH) && 1053 !(cnp->cn_flags & WILLBEDIR)) { 1054 error = ENOENT; 1055 goto bad; 1056 } 1057 if ((cnp->cn_flags & LOCKPARENT) == 0) 1058 VOP_UNLOCK(dp); 1059 /* 1060 * We return with ni_vp NULL to indicate that the entry 1061 * doesn't currently exist, leaving a pointer to the 1062 * (possibly locked) directory vnode in ndp->ni_dvp. 1063 */ 1064 if (cnp->cn_flags & SAVESTART) { 1065 ndp->ni_startdir = ndp->ni_dvp; 1066 VREF(ndp->ni_startdir); 1067 } 1068 goto success; 1069 } 1070 1071 good: 1072 #ifdef NAMEI_DIAGNOSTIC 1073 printf("found\n"); 1074 #endif 1075 dp = ndp->ni_vp; 1076 1077 /* 1078 * Check to see if the vnode has been mounted on; 1079 * if so find the root of the mounted filesystem. 1080 */ 1081 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 1082 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 1083 if (vfs_busy(mp, 0)) 1084 continue; 1085 vput(dp); 1086 if (dp != ndp->ni_dvp) 1087 vput(ndp->ni_dvp); 1088 else 1089 vrele(ndp->ni_dvp); 1090 vrefact(vp_crossmp); 1091 ndp->ni_dvp = vp_crossmp; 1092 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags, 1093 cnp->cn_flags), &tdp); 1094 vfs_unbusy(mp); 1095 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) 1096 panic("vp_crossmp exclusively locked or reclaimed"); 1097 if (error) { 1098 dpunlocked = 1; 1099 goto bad2; 1100 } 1101 ndp->ni_vp = dp = tdp; 1102 } 1103 1104 /* 1105 * Check for symbolic link 1106 */ 1107 if ((dp->v_type == VLNK) && 1108 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) || 1109 *ndp->ni_next == '/')) { 1110 cnp->cn_flags |= ISSYMLINK; 1111 if (VN_IS_DOOMED(dp)) { 1112 /* 1113 * We can't know whether the directory was mounted with 1114 * NOSYMFOLLOW, so we can't follow safely. 1115 */ 1116 error = ENOENT; 1117 goto bad2; 1118 } 1119 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 1120 error = EACCES; 1121 goto bad2; 1122 } 1123 /* 1124 * Symlink code always expects an unlocked dvp. 1125 */ 1126 if (ndp->ni_dvp != ndp->ni_vp) { 1127 VOP_UNLOCK(ndp->ni_dvp); 1128 ni_dvp_unlocked = 1; 1129 } 1130 goto success; 1131 } 1132 1133 nextname: 1134 /* 1135 * Not a symbolic link that we will follow. Continue with the 1136 * next component if there is any; otherwise, we're done. 1137 */ 1138 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 1139 ("lookup: invalid path state.")); 1140 if (relookup) { 1141 relookup = 0; 1142 ndp->ni_pathlen = prev_ni_pathlen; 1143 ndp->ni_next = prev_ni_next; 1144 if (ndp->ni_dvp != dp) 1145 vput(ndp->ni_dvp); 1146 else 1147 vrele(ndp->ni_dvp); 1148 goto dirloop; 1149 } 1150 if (cnp->cn_flags & ISDOTDOT) { 1151 error = nameicap_check_dotdot(ndp, ndp->ni_vp); 1152 if (error != 0) { 1153 #ifdef KTRACE 1154 if (KTRPOINT(curthread, KTR_CAPFAIL)) 1155 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 1156 #endif 1157 goto bad2; 1158 } 1159 } 1160 if (*ndp->ni_next == '/') { 1161 cnp->cn_nameptr = ndp->ni_next; 1162 while (*cnp->cn_nameptr == '/') { 1163 cnp->cn_nameptr++; 1164 ndp->ni_pathlen--; 1165 } 1166 if (ndp->ni_dvp != dp) 1167 vput(ndp->ni_dvp); 1168 else 1169 vrele(ndp->ni_dvp); 1170 goto dirloop; 1171 } 1172 /* 1173 * If we're processing a path with a trailing slash, 1174 * check that the end result is a directory. 1175 */ 1176 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) { 1177 error = ENOTDIR; 1178 goto bad2; 1179 } 1180 /* 1181 * Disallow directory write attempts on read-only filesystems. 1182 */ 1183 if (rdonly && 1184 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1185 error = EROFS; 1186 goto bad2; 1187 } 1188 if (cnp->cn_flags & SAVESTART) { 1189 ndp->ni_startdir = ndp->ni_dvp; 1190 VREF(ndp->ni_startdir); 1191 } 1192 if (!wantparent) { 1193 ni_dvp_unlocked = 2; 1194 if (ndp->ni_dvp != dp) 1195 vput(ndp->ni_dvp); 1196 else 1197 vrele(ndp->ni_dvp); 1198 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { 1199 VOP_UNLOCK(ndp->ni_dvp); 1200 ni_dvp_unlocked = 1; 1201 } 1202 1203 if (cnp->cn_flags & AUDITVNODE1) 1204 AUDIT_ARG_VNODE1(dp); 1205 else if (cnp->cn_flags & AUDITVNODE2) 1206 AUDIT_ARG_VNODE2(dp); 1207 1208 if ((cnp->cn_flags & LOCKLEAF) == 0) 1209 VOP_UNLOCK(dp); 1210 success: 1211 /* 1212 * Because of shared lookup we may have the vnode shared locked, but 1213 * the caller may want it to be exclusively locked. 1214 */ 1215 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && 1216 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { 1217 vn_lock(dp, LK_UPGRADE | LK_RETRY); 1218 if (VN_IS_DOOMED(dp)) { 1219 error = ENOENT; 1220 goto bad2; 1221 } 1222 } 1223 return (0); 1224 1225 bad2: 1226 if (ni_dvp_unlocked != 2) { 1227 if (dp != ndp->ni_dvp && !ni_dvp_unlocked) 1228 vput(ndp->ni_dvp); 1229 else 1230 vrele(ndp->ni_dvp); 1231 } 1232 bad: 1233 if (!dpunlocked) 1234 vput(dp); 1235 ndp->ni_vp = NULL; 1236 return (error); 1237 } 1238 1239 /* 1240 * relookup - lookup a path name component 1241 * Used by lookup to re-acquire things. 1242 */ 1243 int 1244 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 1245 { 1246 struct vnode *dp = NULL; /* the directory we are searching */ 1247 int wantparent; /* 1 => wantparent or lockparent flag */ 1248 int rdonly; /* lookup read-only flag bit */ 1249 int error = 0; 1250 1251 KASSERT(cnp->cn_flags & ISLASTCN, 1252 ("relookup: Not given last component.")); 1253 /* 1254 * Setup: break out flag bits into variables. 1255 */ 1256 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 1257 KASSERT(wantparent, ("relookup: parent not wanted.")); 1258 rdonly = cnp->cn_flags & RDONLY; 1259 cnp->cn_flags &= ~ISSYMLINK; 1260 dp = dvp; 1261 cnp->cn_lkflags = LK_EXCLUSIVE; 1262 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 1263 1264 /* 1265 * Search a new directory. 1266 * 1267 * The last component of the filename is left accessible via 1268 * cnp->cn_nameptr for callers that need the name. Callers needing 1269 * the name set the SAVENAME flag. When done, they assume 1270 * responsibility for freeing the pathname buffer. 1271 */ 1272 #ifdef NAMEI_DIAGNOSTIC 1273 printf("{%s}: ", cnp->cn_nameptr); 1274 #endif 1275 1276 /* 1277 * Check for "" which represents the root directory after slash 1278 * removal. 1279 */ 1280 if (cnp->cn_nameptr[0] == '\0') { 1281 /* 1282 * Support only LOOKUP for "/" because lookup() 1283 * can't succeed for CREATE, DELETE and RENAME. 1284 */ 1285 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP")); 1286 KASSERT(dp->v_type == VDIR, ("dp is not a directory")); 1287 1288 if (!(cnp->cn_flags & LOCKLEAF)) 1289 VOP_UNLOCK(dp); 1290 *vpp = dp; 1291 /* XXX This should probably move to the top of function. */ 1292 if (cnp->cn_flags & SAVESTART) 1293 panic("lookup: SAVESTART"); 1294 return (0); 1295 } 1296 1297 if (cnp->cn_flags & ISDOTDOT) 1298 panic ("relookup: lookup on dot-dot"); 1299 1300 /* 1301 * We now have a segment name to search for, and a directory to search. 1302 */ 1303 #ifdef NAMEI_DIAGNOSTIC 1304 vn_printf(dp, "search in "); 1305 #endif 1306 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 1307 KASSERT(*vpp == NULL, ("leaf should be empty")); 1308 if (error != EJUSTRETURN) 1309 goto bad; 1310 /* 1311 * If creating and at end of pathname, then can consider 1312 * allowing file to be created. 1313 */ 1314 if (rdonly) { 1315 error = EROFS; 1316 goto bad; 1317 } 1318 /* ASSERT(dvp == ndp->ni_startdir) */ 1319 if (cnp->cn_flags & SAVESTART) 1320 VREF(dvp); 1321 if ((cnp->cn_flags & LOCKPARENT) == 0) 1322 VOP_UNLOCK(dp); 1323 /* 1324 * We return with ni_vp NULL to indicate that the entry 1325 * doesn't currently exist, leaving a pointer to the 1326 * (possibly locked) directory vnode in ndp->ni_dvp. 1327 */ 1328 return (0); 1329 } 1330 1331 dp = *vpp; 1332 1333 /* 1334 * Disallow directory write attempts on read-only filesystems. 1335 */ 1336 if (rdonly && 1337 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1338 if (dvp == dp) 1339 vrele(dvp); 1340 else 1341 vput(dvp); 1342 error = EROFS; 1343 goto bad; 1344 } 1345 /* 1346 * Set the parent lock/ref state to the requested state. 1347 */ 1348 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { 1349 if (wantparent) 1350 VOP_UNLOCK(dvp); 1351 else 1352 vput(dvp); 1353 } else if (!wantparent) 1354 vrele(dvp); 1355 /* 1356 * Check for symbolic link 1357 */ 1358 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 1359 ("relookup: symlink found.\n")); 1360 1361 /* ASSERT(dvp == ndp->ni_startdir) */ 1362 if (cnp->cn_flags & SAVESTART) 1363 VREF(dvp); 1364 1365 if ((cnp->cn_flags & LOCKLEAF) == 0) 1366 VOP_UNLOCK(dp); 1367 return (0); 1368 bad: 1369 vput(dp); 1370 *vpp = NULL; 1371 return (error); 1372 } 1373 1374 /* 1375 * Free data allocated by namei(); see namei(9) for details. 1376 */ 1377 void 1378 NDFREE_PNBUF(struct nameidata *ndp) 1379 { 1380 1381 if ((ndp->ni_cnd.cn_flags & HASBUF) != 0) { 1382 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 1383 ndp->ni_cnd.cn_flags &= ~HASBUF; 1384 } 1385 } 1386 1387 void 1388 (NDFREE)(struct nameidata *ndp, const u_int flags) 1389 { 1390 int unlock_dvp; 1391 int unlock_vp; 1392 1393 unlock_dvp = 0; 1394 unlock_vp = 0; 1395 1396 if (!(flags & NDF_NO_FREE_PNBUF)) { 1397 NDFREE_PNBUF(ndp); 1398 } 1399 if (!(flags & NDF_NO_VP_UNLOCK) && 1400 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 1401 unlock_vp = 1; 1402 if (!(flags & NDF_NO_DVP_UNLOCK) && 1403 (ndp->ni_cnd.cn_flags & LOCKPARENT) && 1404 ndp->ni_dvp != ndp->ni_vp) 1405 unlock_dvp = 1; 1406 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 1407 if (unlock_vp) { 1408 vput(ndp->ni_vp); 1409 unlock_vp = 0; 1410 } else 1411 vrele(ndp->ni_vp); 1412 ndp->ni_vp = NULL; 1413 } 1414 if (unlock_vp) 1415 VOP_UNLOCK(ndp->ni_vp); 1416 if (!(flags & NDF_NO_DVP_RELE) && 1417 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 1418 if (unlock_dvp) { 1419 vput(ndp->ni_dvp); 1420 unlock_dvp = 0; 1421 } else 1422 vrele(ndp->ni_dvp); 1423 ndp->ni_dvp = NULL; 1424 } 1425 if (unlock_dvp) 1426 VOP_UNLOCK(ndp->ni_dvp); 1427 if (!(flags & NDF_NO_STARTDIR_RELE) && 1428 (ndp->ni_cnd.cn_flags & SAVESTART)) { 1429 vrele(ndp->ni_startdir); 1430 ndp->ni_startdir = NULL; 1431 } 1432 } 1433 1434 /* 1435 * Determine if there is a suitable alternate filename under the specified 1436 * prefix for the specified path. If the create flag is set, then the 1437 * alternate prefix will be used so long as the parent directory exists. 1438 * This is used by the various compatibility ABIs so that Linux binaries prefer 1439 * files under /compat/linux for example. The chosen path (whether under 1440 * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1441 * to by pathbuf. The caller is responsible for free'ing the buffer from 1442 * the M_TEMP bucket if one is returned. 1443 */ 1444 int 1445 kern_alternate_path(struct thread *td, const char *prefix, const char *path, 1446 enum uio_seg pathseg, char **pathbuf, int create, int dirfd) 1447 { 1448 struct nameidata nd, ndroot; 1449 char *ptr, *buf, *cp; 1450 size_t len, sz; 1451 int error; 1452 1453 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1454 *pathbuf = buf; 1455 1456 /* Copy the prefix into the new pathname as a starting point. */ 1457 len = strlcpy(buf, prefix, MAXPATHLEN); 1458 if (len >= MAXPATHLEN) { 1459 *pathbuf = NULL; 1460 free(buf, M_TEMP); 1461 return (EINVAL); 1462 } 1463 sz = MAXPATHLEN - len; 1464 ptr = buf + len; 1465 1466 /* Append the filename to the prefix. */ 1467 if (pathseg == UIO_SYSSPACE) 1468 error = copystr(path, ptr, sz, &len); 1469 else 1470 error = copyinstr(path, ptr, sz, &len); 1471 1472 if (error) { 1473 *pathbuf = NULL; 1474 free(buf, M_TEMP); 1475 return (error); 1476 } 1477 1478 /* Only use a prefix with absolute pathnames. */ 1479 if (*ptr != '/') { 1480 error = EINVAL; 1481 goto keeporig; 1482 } 1483 1484 if (dirfd != AT_FDCWD) { 1485 /* 1486 * We want the original because the "prefix" is 1487 * included in the already opened dirfd. 1488 */ 1489 bcopy(ptr, buf, len); 1490 return (0); 1491 } 1492 1493 /* 1494 * We know that there is a / somewhere in this pathname. 1495 * Search backwards for it, to find the file's parent dir 1496 * to see if it exists in the alternate tree. If it does, 1497 * and we want to create a file (cflag is set). We don't 1498 * need to worry about the root comparison in this case. 1499 */ 1500 1501 if (create) { 1502 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1503 *cp = '\0'; 1504 1505 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td); 1506 error = namei(&nd); 1507 *cp = '/'; 1508 if (error != 0) 1509 goto keeporig; 1510 } else { 1511 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td); 1512 1513 error = namei(&nd); 1514 if (error != 0) 1515 goto keeporig; 1516 1517 /* 1518 * We now compare the vnode of the prefix to the one 1519 * vnode asked. If they resolve to be the same, then we 1520 * ignore the match so that the real root gets used. 1521 * This avoids the problem of traversing "../.." to find the 1522 * root directory and never finding it, because "/" resolves 1523 * to the emulation root directory. This is expensive :-( 1524 */ 1525 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix, 1526 td); 1527 1528 /* We shouldn't ever get an error from this namei(). */ 1529 error = namei(&ndroot); 1530 if (error == 0) { 1531 if (nd.ni_vp == ndroot.ni_vp) 1532 error = ENOENT; 1533 1534 NDFREE(&ndroot, NDF_ONLY_PNBUF); 1535 vrele(ndroot.ni_vp); 1536 } 1537 } 1538 1539 NDFREE(&nd, NDF_ONLY_PNBUF); 1540 vrele(nd.ni_vp); 1541 1542 keeporig: 1543 /* If there was an error, use the original path name. */ 1544 if (error) 1545 bcopy(ptr, buf, len); 1546 return (error); 1547 } 1548