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 65 #include <security/audit/audit.h> 66 #include <security/mac/mac_framework.h> 67 68 #include <vm/uma.h> 69 70 #define NAMEI_DIAGNOSTIC 1 71 #undef NAMEI_DIAGNOSTIC 72 73 SDT_PROVIDER_DECLARE(vfs); 74 SDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *", 75 "unsigned long"); 76 SDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *"); 77 78 /* Allocation zone for namei. */ 79 uma_zone_t namei_zone; 80 81 /* Placeholder vnode for mp traversal. */ 82 static struct vnode *vp_crossmp; 83 84 static int 85 crossmp_vop_islocked(struct vop_islocked_args *ap) 86 { 87 88 return (LK_SHARED); 89 } 90 91 static int 92 crossmp_vop_lock1(struct vop_lock1_args *ap) 93 { 94 struct vnode *vp; 95 struct lock *lk __unused; 96 const char *file __unused; 97 int flags, line __unused; 98 99 vp = ap->a_vp; 100 lk = vp->v_vnlock; 101 flags = ap->a_flags; 102 file = ap->a_file; 103 line = ap->a_line; 104 105 if ((flags & LK_SHARED) == 0) 106 panic("invalid lock request for crossmp"); 107 108 WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER, file, line, 109 flags & LK_INTERLOCK ? &VI_MTX(vp)->lock_object : NULL); 110 WITNESS_LOCK(&lk->lock_object, 0, file, line); 111 if ((flags & LK_INTERLOCK) != 0) 112 VI_UNLOCK(vp); 113 LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, line); 114 return (0); 115 } 116 117 static int 118 crossmp_vop_unlock(struct vop_unlock_args *ap) 119 { 120 struct vnode *vp; 121 struct lock *lk __unused; 122 int flags; 123 124 vp = ap->a_vp; 125 lk = vp->v_vnlock; 126 flags = ap->a_flags; 127 128 if ((flags & LK_INTERLOCK) != 0) 129 VI_UNLOCK(vp); 130 WITNESS_UNLOCK(&lk->lock_object, 0, LOCK_FILE, LOCK_LINE); 131 LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE, 132 LOCK_LINE); 133 return (0); 134 } 135 136 static struct vop_vector crossmp_vnodeops = { 137 .vop_default = &default_vnodeops, 138 .vop_islocked = crossmp_vop_islocked, 139 .vop_lock1 = crossmp_vop_lock1, 140 .vop_unlock = crossmp_vop_unlock, 141 }; 142 143 struct nameicap_tracker { 144 struct vnode *dp; 145 TAILQ_ENTRY(nameicap_tracker) nm_link; 146 }; 147 148 /* Zone for cap mode tracker elements used for dotdot capability checks. */ 149 static uma_zone_t nt_zone; 150 151 static void 152 nameiinit(void *dummy __unused) 153 { 154 155 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, 156 UMA_ALIGN_PTR, 0); 157 nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker), 158 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 159 getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp); 160 } 161 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); 162 163 static int lookup_cap_dotdot = 1; 164 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN, 165 &lookup_cap_dotdot, 0, 166 "enables \"..\" components in path lookup in capability mode"); 167 static int lookup_cap_dotdot_nonlocal = 1; 168 SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN, 169 &lookup_cap_dotdot_nonlocal, 0, 170 "enables \"..\" components in path lookup in capability mode " 171 "on non-local mount"); 172 173 static void 174 nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp) 175 { 176 struct nameicap_tracker *nt; 177 178 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR) 179 return; 180 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_BENEATH_LATCHED)) == 181 NI_LCF_BENEATH_ABS) { 182 MPASS((ndp->ni_lcf & NI_LCF_LATCH) != 0); 183 if (dp != ndp->ni_beneath_latch) 184 return; 185 ndp->ni_lcf |= NI_LCF_BENEATH_LATCHED; 186 } 187 nt = uma_zalloc(nt_zone, M_WAITOK); 188 vhold(dp); 189 nt->dp = dp; 190 TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link); 191 } 192 193 static void 194 nameicap_cleanup(struct nameidata *ndp, bool clean_latch) 195 { 196 struct nameicap_tracker *nt, *nt1; 197 198 KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) || 199 (ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative")); 200 TAILQ_FOREACH_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) { 201 TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link); 202 vdrop(nt->dp); 203 uma_zfree(nt_zone, nt); 204 } 205 if (clean_latch && (ndp->ni_lcf & NI_LCF_LATCH) != 0) { 206 ndp->ni_lcf &= ~NI_LCF_LATCH; 207 vrele(ndp->ni_beneath_latch); 208 } 209 } 210 211 /* 212 * For dotdot lookups in capability mode, only allow the component 213 * lookup to succeed if the resulting directory was already traversed 214 * during the operation. Also fail dotdot lookups for non-local 215 * filesystems, where external agents might assist local lookups to 216 * escape the compartment. 217 */ 218 static int 219 nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp) 220 { 221 struct nameicap_tracker *nt; 222 struct mount *mp; 223 224 if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp == NULL || 225 dp->v_type != VDIR) 226 return (0); 227 mp = dp->v_mount; 228 if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL && 229 (mp->mnt_flag & MNT_LOCAL) == 0) 230 return (ENOTCAPABLE); 231 TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head, 232 nm_link) { 233 if (dp == nt->dp) 234 return (0); 235 } 236 if ((ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) { 237 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED; 238 nameicap_cleanup(ndp, false); 239 return (0); 240 } 241 return (ENOTCAPABLE); 242 } 243 244 static void 245 namei_cleanup_cnp(struct componentname *cnp) 246 { 247 248 uma_zfree(namei_zone, cnp->cn_pnbuf); 249 #ifdef DIAGNOSTIC 250 cnp->cn_pnbuf = NULL; 251 cnp->cn_nameptr = NULL; 252 #endif 253 } 254 255 static int 256 namei_handle_root(struct nameidata *ndp, struct vnode **dpp) 257 { 258 struct componentname *cnp; 259 260 cnp = &ndp->ni_cnd; 261 if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0) { 262 #ifdef KTRACE 263 if (KTRPOINT(curthread, KTR_CAPFAIL)) 264 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 265 #endif 266 return (ENOTCAPABLE); 267 } 268 if ((cnp->cn_flags & BENEATH) != 0) { 269 ndp->ni_lcf |= NI_LCF_BENEATH_ABS; 270 ndp->ni_lcf &= ~NI_LCF_BENEATH_LATCHED; 271 nameicap_cleanup(ndp, false); 272 } 273 while (*(cnp->cn_nameptr) == '/') { 274 cnp->cn_nameptr++; 275 ndp->ni_pathlen--; 276 } 277 *dpp = ndp->ni_rootdir; 278 vrefact(*dpp); 279 return (0); 280 } 281 282 /* 283 * Convert a pathname into a pointer to a locked vnode. 284 * 285 * The FOLLOW flag is set when symbolic links are to be followed 286 * when they occur at the end of the name translation process. 287 * Symbolic links are always followed for all other pathname 288 * components other than the last. 289 * 290 * The segflg defines whether the name is to be copied from user 291 * space or kernel space. 292 * 293 * Overall outline of namei: 294 * 295 * copy in name 296 * get starting directory 297 * while (!done && !error) { 298 * call lookup to search path. 299 * if symbolic link, massage name in buffer and continue 300 * } 301 */ 302 int 303 namei(struct nameidata *ndp) 304 { 305 struct filedesc *fdp; /* pointer to file descriptor state */ 306 char *cp; /* pointer into pathname argument */ 307 struct vnode *dp; /* the directory we are searching */ 308 struct iovec aiov; /* uio for reading symbolic links */ 309 struct componentname *cnp; 310 struct thread *td; 311 struct proc *p; 312 cap_rights_t rights; 313 struct filecaps dirfd_caps; 314 struct uio auio; 315 int error, linklen, startdir_used; 316 317 cnp = &ndp->ni_cnd; 318 td = cnp->cn_thread; 319 p = td->td_proc; 320 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; 321 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc")); 322 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, 323 ("namei: nameiop contaminated with flags")); 324 KASSERT((cnp->cn_flags & OPMASK) == 0, 325 ("namei: flags contaminated with nameiops")); 326 MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR || 327 ndp->ni_startdir->v_type == VBAD); 328 fdp = p->p_fd; 329 TAILQ_INIT(&ndp->ni_cap_tracker); 330 ndp->ni_lcf = 0; 331 332 /* We will set this ourselves if we need it. */ 333 cnp->cn_flags &= ~TRAILINGSLASH; 334 335 /* 336 * Get a buffer for the name to be translated, and copy the 337 * name into the buffer. 338 */ 339 if ((cnp->cn_flags & HASBUF) == 0) 340 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); 341 if (ndp->ni_segflg == UIO_SYSSPACE) 342 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, 343 &ndp->ni_pathlen); 344 else 345 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, 346 &ndp->ni_pathlen); 347 348 /* 349 * Don't allow empty pathnames. 350 */ 351 if (error == 0 && *cnp->cn_pnbuf == '\0') 352 error = ENOENT; 353 354 #ifdef CAPABILITY_MODE 355 /* 356 * In capability mode, lookups must be restricted to happen in 357 * the subtree with the root specified by the file descriptor: 358 * - The root must be real file descriptor, not the pseudo-descriptor 359 * AT_FDCWD. 360 * - The passed path must be relative and not absolute. 361 * - If lookup_cap_dotdot is disabled, path must not contain the 362 * '..' components. 363 * - If lookup_cap_dotdot is enabled, we verify that all '..' 364 * components lookups result in the directories which were 365 * previously walked by us, which prevents an escape from 366 * the relative root. 367 */ 368 if (error == 0 && IN_CAPABILITY_MODE(td) && 369 (cnp->cn_flags & NOCAPCHECK) == 0) { 370 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; 371 if (ndp->ni_dirfd == AT_FDCWD) { 372 #ifdef KTRACE 373 if (KTRPOINT(td, KTR_CAPFAIL)) 374 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 375 #endif 376 error = ECAPMODE; 377 } 378 } 379 #endif 380 if (error != 0) { 381 namei_cleanup_cnp(cnp); 382 ndp->ni_vp = NULL; 383 return (error); 384 } 385 ndp->ni_loopcnt = 0; 386 #ifdef KTRACE 387 if (KTRPOINT(td, KTR_NAMEI)) { 388 KASSERT(cnp->cn_thread == curthread, 389 ("namei not using curthread")); 390 ktrnamei(cnp->cn_pnbuf); 391 } 392 #endif 393 /* 394 * Get starting point for the translation. 395 */ 396 FILEDESC_SLOCK(fdp); 397 ndp->ni_rootdir = fdp->fd_rdir; 398 vrefact(ndp->ni_rootdir); 399 ndp->ni_topdir = fdp->fd_jdir; 400 401 /* 402 * If we are auditing the kernel pathname, save the user pathname. 403 */ 404 if (cnp->cn_flags & AUDITVNODE1) 405 AUDIT_ARG_UPATH1(td, ndp->ni_dirfd, cnp->cn_pnbuf); 406 if (cnp->cn_flags & AUDITVNODE2) 407 AUDIT_ARG_UPATH2(td, ndp->ni_dirfd, cnp->cn_pnbuf); 408 409 startdir_used = 0; 410 dp = NULL; 411 cnp->cn_nameptr = cnp->cn_pnbuf; 412 if (cnp->cn_pnbuf[0] == '/') { 413 error = namei_handle_root(ndp, &dp); 414 } else { 415 if (ndp->ni_startdir != NULL) { 416 dp = ndp->ni_startdir; 417 startdir_used = 1; 418 } else if (ndp->ni_dirfd == AT_FDCWD) { 419 dp = fdp->fd_cdir; 420 vrefact(dp); 421 } else { 422 rights = ndp->ni_rightsneeded; 423 cap_rights_set(&rights, CAP_LOOKUP); 424 425 if (cnp->cn_flags & AUDITVNODE1) 426 AUDIT_ARG_ATFD1(ndp->ni_dirfd); 427 if (cnp->cn_flags & AUDITVNODE2) 428 AUDIT_ARG_ATFD2(ndp->ni_dirfd); 429 error = fgetvp_rights(td, ndp->ni_dirfd, 430 &rights, &ndp->ni_filecaps, &dp); 431 if (error == EINVAL) 432 error = ENOTDIR; 433 #ifdef CAPABILITIES 434 /* 435 * If file descriptor doesn't have all rights, 436 * all lookups relative to it must also be 437 * strictly relative. 438 */ 439 CAP_ALL(&rights); 440 if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights, 441 &rights) || 442 ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL || 443 ndp->ni_filecaps.fc_nioctls != -1) { 444 ndp->ni_lcf |= NI_LCF_STRICTRELATIVE; 445 } 446 #endif 447 } 448 if (error == 0 && dp->v_type != VDIR) 449 error = ENOTDIR; 450 } 451 if (error == 0 && (cnp->cn_flags & BENEATH) != 0) { 452 if (ndp->ni_dirfd == AT_FDCWD) { 453 ndp->ni_beneath_latch = fdp->fd_cdir; 454 vrefact(ndp->ni_beneath_latch); 455 } else { 456 rights = ndp->ni_rightsneeded; 457 cap_rights_set(&rights, CAP_LOOKUP); 458 error = fgetvp_rights(td, ndp->ni_dirfd, &rights, 459 &dirfd_caps, &ndp->ni_beneath_latch); 460 if (error == 0 && dp->v_type != VDIR) { 461 vrele(ndp->ni_beneath_latch); 462 error = ENOTDIR; 463 } 464 } 465 if (error == 0) 466 ndp->ni_lcf |= NI_LCF_LATCH; 467 } 468 FILEDESC_SUNLOCK(fdp); 469 if (ndp->ni_startdir != NULL && !startdir_used) 470 vrele(ndp->ni_startdir); 471 if (error != 0) { 472 if (dp != NULL) 473 vrele(dp); 474 goto out; 475 } 476 MPASS((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | NI_LCF_LATCH)) != 477 NI_LCF_BENEATH_ABS); 478 if (((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) != 0 && 479 lookup_cap_dotdot != 0) || 480 ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0 && 481 (cnp->cn_flags & BENEATH) != 0)) 482 ndp->ni_lcf |= NI_LCF_CAP_DOTDOT; 483 SDT_PROBE3(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf, 484 cnp->cn_flags); 485 for (;;) { 486 ndp->ni_startdir = dp; 487 error = lookup(ndp); 488 if (error != 0) 489 goto out; 490 /* 491 * If not a symbolic link, we're done. 492 */ 493 if ((cnp->cn_flags & ISSYMLINK) == 0) { 494 vrele(ndp->ni_rootdir); 495 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 496 namei_cleanup_cnp(cnp); 497 } else 498 cnp->cn_flags |= HASBUF; 499 if ((ndp->ni_lcf & (NI_LCF_BENEATH_ABS | 500 NI_LCF_BENEATH_LATCHED)) == NI_LCF_BENEATH_ABS) { 501 NDFREE(ndp, 0); 502 error = ENOTCAPABLE; 503 } 504 nameicap_cleanup(ndp, true); 505 SDT_PROBE2(vfs, namei, lookup, return, error, 506 (error == 0 ? ndp->ni_vp : NULL)); 507 return (error); 508 } 509 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 510 error = ELOOP; 511 break; 512 } 513 #ifdef MAC 514 if ((cnp->cn_flags & NOMACCHECK) == 0) { 515 error = mac_vnode_check_readlink(td->td_ucred, 516 ndp->ni_vp); 517 if (error != 0) 518 break; 519 } 520 #endif 521 if (ndp->ni_pathlen > 1) 522 cp = uma_zalloc(namei_zone, M_WAITOK); 523 else 524 cp = cnp->cn_pnbuf; 525 aiov.iov_base = cp; 526 aiov.iov_len = MAXPATHLEN; 527 auio.uio_iov = &aiov; 528 auio.uio_iovcnt = 1; 529 auio.uio_offset = 0; 530 auio.uio_rw = UIO_READ; 531 auio.uio_segflg = UIO_SYSSPACE; 532 auio.uio_td = td; 533 auio.uio_resid = MAXPATHLEN; 534 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 535 if (error != 0) { 536 if (ndp->ni_pathlen > 1) 537 uma_zfree(namei_zone, cp); 538 break; 539 } 540 linklen = MAXPATHLEN - auio.uio_resid; 541 if (linklen == 0) { 542 if (ndp->ni_pathlen > 1) 543 uma_zfree(namei_zone, cp); 544 error = ENOENT; 545 break; 546 } 547 if (linklen + ndp->ni_pathlen > MAXPATHLEN) { 548 if (ndp->ni_pathlen > 1) 549 uma_zfree(namei_zone, cp); 550 error = ENAMETOOLONG; 551 break; 552 } 553 if (ndp->ni_pathlen > 1) { 554 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 555 uma_zfree(namei_zone, cnp->cn_pnbuf); 556 cnp->cn_pnbuf = cp; 557 } else 558 cnp->cn_pnbuf[linklen] = '\0'; 559 ndp->ni_pathlen += linklen; 560 vput(ndp->ni_vp); 561 dp = ndp->ni_dvp; 562 /* 563 * Check if root directory should replace current directory. 564 */ 565 cnp->cn_nameptr = cnp->cn_pnbuf; 566 if (*(cnp->cn_nameptr) == '/') { 567 vrele(dp); 568 error = namei_handle_root(ndp, &dp); 569 if (error != 0) 570 goto out; 571 } 572 } 573 vput(ndp->ni_vp); 574 ndp->ni_vp = NULL; 575 vrele(ndp->ni_dvp); 576 out: 577 vrele(ndp->ni_rootdir); 578 MPASS(error != 0); 579 namei_cleanup_cnp(cnp); 580 nameicap_cleanup(ndp, true); 581 SDT_PROBE2(vfs, namei, lookup, return, error, NULL); 582 return (error); 583 } 584 585 static int 586 compute_cn_lkflags(struct mount *mp, int lkflags, int cnflags) 587 { 588 589 if (mp == NULL || ((lkflags & LK_SHARED) && 590 (!(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED) || 591 ((cnflags & ISDOTDOT) && 592 (mp->mnt_kern_flag & MNTK_LOOKUP_EXCL_DOTDOT))))) { 593 lkflags &= ~LK_SHARED; 594 lkflags |= LK_EXCLUSIVE; 595 } 596 lkflags |= LK_NODDLKTREAT; 597 return (lkflags); 598 } 599 600 static __inline int 601 needs_exclusive_leaf(struct mount *mp, int flags) 602 { 603 604 /* 605 * Intermediate nodes can use shared locks, we only need to 606 * force an exclusive lock for leaf nodes. 607 */ 608 if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) 609 return (0); 610 611 /* Always use exclusive locks if LOCKSHARED isn't set. */ 612 if (!(flags & LOCKSHARED)) 613 return (1); 614 615 /* 616 * For lookups during open(), if the mount point supports 617 * extended shared operations, then use a shared lock for the 618 * leaf node, otherwise use an exclusive lock. 619 */ 620 if ((flags & ISOPEN) != 0) 621 return (!MNT_EXTENDED_SHARED(mp)); 622 623 /* 624 * Lookup requests outside of open() that specify LOCKSHARED 625 * only need a shared lock on the leaf vnode. 626 */ 627 return (0); 628 } 629 630 /* 631 * Search a pathname. 632 * This is a very central and rather complicated routine. 633 * 634 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 635 * The starting directory is taken from ni_startdir. The pathname is 636 * descended until done, or a symbolic link is encountered. The variable 637 * ni_more is clear if the path is completed; it is set to one if a 638 * symbolic link needing interpretation is encountered. 639 * 640 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 641 * whether the name is to be looked up, created, renamed, or deleted. 642 * When CREATE, RENAME, or DELETE is specified, information usable in 643 * creating, renaming, or deleting a directory entry may be calculated. 644 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 645 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 646 * returned unlocked. Otherwise the parent directory is not returned. If 647 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 648 * the target is returned locked, otherwise it is returned unlocked. 649 * When creating or renaming and LOCKPARENT is specified, the target may not 650 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 651 * 652 * Overall outline of lookup: 653 * 654 * dirloop: 655 * identify next component of name at ndp->ni_ptr 656 * handle degenerate case where name is null string 657 * if .. and crossing mount points and on mounted filesys, find parent 658 * call VOP_LOOKUP routine for next component name 659 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 660 * component vnode returned in ni_vp (if it exists), locked. 661 * if result vnode is mounted on and crossing mount points, 662 * find mounted on vnode 663 * if more components of name, do next level at dirloop 664 * return the answer in ni_vp, locked if LOCKLEAF set 665 * if LOCKPARENT set, return locked parent in ni_dvp 666 * if WANTPARENT set, return unlocked parent in ni_dvp 667 */ 668 int 669 lookup(struct nameidata *ndp) 670 { 671 char *cp; /* pointer into pathname argument */ 672 char *prev_ni_next; /* saved ndp->ni_next */ 673 struct vnode *dp = NULL; /* the directory we are searching */ 674 struct vnode *tdp; /* saved dp */ 675 struct mount *mp; /* mount table entry */ 676 struct prison *pr; 677 size_t prev_ni_pathlen; /* saved ndp->ni_pathlen */ 678 int docache; /* == 0 do not cache last component */ 679 int wantparent; /* 1 => wantparent or lockparent flag */ 680 int rdonly; /* lookup read-only flag bit */ 681 int error = 0; 682 int dpunlocked = 0; /* dp has already been unlocked */ 683 int relookup = 0; /* do not consume the path component */ 684 struct componentname *cnp = &ndp->ni_cnd; 685 int lkflags_save; 686 int ni_dvp_unlocked; 687 688 /* 689 * Setup: break out flag bits into variables. 690 */ 691 ni_dvp_unlocked = 0; 692 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 693 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 694 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 695 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 696 if (cnp->cn_nameiop == DELETE || 697 (wantparent && cnp->cn_nameiop != CREATE && 698 cnp->cn_nameiop != LOOKUP)) 699 docache = 0; 700 rdonly = cnp->cn_flags & RDONLY; 701 cnp->cn_flags &= ~ISSYMLINK; 702 ndp->ni_dvp = NULL; 703 /* 704 * We use shared locks until we hit the parent of the last cn then 705 * we adjust based on the requesting flags. 706 */ 707 cnp->cn_lkflags = LK_SHARED; 708 dp = ndp->ni_startdir; 709 ndp->ni_startdir = NULLVP; 710 vn_lock(dp, 711 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY, 712 cnp->cn_flags)); 713 714 dirloop: 715 /* 716 * Search a new directory. 717 * 718 * The last component of the filename is left accessible via 719 * cnp->cn_nameptr for callers that need the name. Callers needing 720 * the name set the SAVENAME flag. When done, they assume 721 * responsibility for freeing the pathname buffer. 722 */ 723 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 724 continue; 725 cnp->cn_namelen = cp - cnp->cn_nameptr; 726 if (cnp->cn_namelen > NAME_MAX) { 727 error = ENAMETOOLONG; 728 goto bad; 729 } 730 #ifdef NAMEI_DIAGNOSTIC 731 { char c = *cp; 732 *cp = '\0'; 733 printf("{%s}: ", cnp->cn_nameptr); 734 *cp = c; } 735 #endif 736 prev_ni_pathlen = ndp->ni_pathlen; 737 ndp->ni_pathlen -= cnp->cn_namelen; 738 KASSERT(ndp->ni_pathlen <= PATH_MAX, 739 ("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen)); 740 prev_ni_next = ndp->ni_next; 741 ndp->ni_next = cp; 742 743 /* 744 * Replace multiple slashes by a single slash and trailing slashes 745 * by a null. This must be done before VOP_LOOKUP() because some 746 * fs's don't know about trailing slashes. Remember if there were 747 * trailing slashes to handle symlinks, existing non-directories 748 * and non-existing files that won't be directories specially later. 749 */ 750 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 751 cp++; 752 ndp->ni_pathlen--; 753 if (*cp == '\0') { 754 *ndp->ni_next = '\0'; 755 cnp->cn_flags |= TRAILINGSLASH; 756 } 757 } 758 ndp->ni_next = cp; 759 760 cnp->cn_flags |= MAKEENTRY; 761 if (*cp == '\0' && docache == 0) 762 cnp->cn_flags &= ~MAKEENTRY; 763 if (cnp->cn_namelen == 2 && 764 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 765 cnp->cn_flags |= ISDOTDOT; 766 else 767 cnp->cn_flags &= ~ISDOTDOT; 768 if (*ndp->ni_next == 0) 769 cnp->cn_flags |= ISLASTCN; 770 else 771 cnp->cn_flags &= ~ISLASTCN; 772 773 if ((cnp->cn_flags & ISLASTCN) != 0 && 774 cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.' && 775 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 776 error = EINVAL; 777 goto bad; 778 } 779 780 nameicap_tracker_add(ndp, dp); 781 782 /* 783 * Check for degenerate name (e.g. / or "") 784 * which is a way of talking about a directory, 785 * e.g. like "/." or ".". 786 */ 787 if (cnp->cn_nameptr[0] == '\0') { 788 if (dp->v_type != VDIR) { 789 error = ENOTDIR; 790 goto bad; 791 } 792 if (cnp->cn_nameiop != LOOKUP) { 793 error = EISDIR; 794 goto bad; 795 } 796 if (wantparent) { 797 ndp->ni_dvp = dp; 798 VREF(dp); 799 } 800 ndp->ni_vp = dp; 801 802 if (cnp->cn_flags & AUDITVNODE1) 803 AUDIT_ARG_VNODE1(dp); 804 else if (cnp->cn_flags & AUDITVNODE2) 805 AUDIT_ARG_VNODE2(dp); 806 807 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 808 VOP_UNLOCK(dp, 0); 809 /* XXX This should probably move to the top of function. */ 810 if (cnp->cn_flags & SAVESTART) 811 panic("lookup: SAVESTART"); 812 goto success; 813 } 814 815 /* 816 * Handle "..": five special cases. 817 * 0. If doing a capability lookup and lookup_cap_dotdot is 818 * disabled, return ENOTCAPABLE. 819 * 1. Return an error if this is the last component of 820 * the name and the operation is DELETE or RENAME. 821 * 2. If at root directory (e.g. after chroot) 822 * or at absolute root directory 823 * then ignore it so can't get out. 824 * 3. If this vnode is the root of a mounted 825 * filesystem, then replace it with the 826 * vnode which was mounted on so we take the 827 * .. in the other filesystem. 828 * 4. If the vnode is the top directory of 829 * the jail or chroot, don't let them out. 830 * 5. If doing a capability lookup and lookup_cap_dotdot is 831 * enabled, return ENOTCAPABLE if the lookup would escape 832 * from the initial file descriptor directory. Checks are 833 * done by ensuring that namei() already traversed the 834 * result of dotdot lookup. 835 */ 836 if (cnp->cn_flags & ISDOTDOT) { 837 if ((ndp->ni_lcf & (NI_LCF_STRICTRELATIVE | NI_LCF_CAP_DOTDOT)) 838 == NI_LCF_STRICTRELATIVE) { 839 #ifdef KTRACE 840 if (KTRPOINT(curthread, KTR_CAPFAIL)) 841 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 842 #endif 843 error = ENOTCAPABLE; 844 goto bad; 845 } 846 if ((cnp->cn_flags & ISLASTCN) != 0 && 847 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 848 error = EINVAL; 849 goto bad; 850 } 851 for (;;) { 852 for (pr = cnp->cn_cred->cr_prison; pr != NULL; 853 pr = pr->pr_parent) 854 if (dp == pr->pr_root) 855 break; 856 if (dp == ndp->ni_rootdir || 857 dp == ndp->ni_topdir || 858 dp == rootvnode || 859 pr != NULL || 860 ((dp->v_vflag & VV_ROOT) != 0 && 861 (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 862 ndp->ni_dvp = dp; 863 ndp->ni_vp = dp; 864 VREF(dp); 865 goto nextname; 866 } 867 if ((dp->v_vflag & VV_ROOT) == 0) 868 break; 869 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */ 870 error = ENOENT; 871 goto bad; 872 } 873 tdp = dp; 874 dp = dp->v_mount->mnt_vnodecovered; 875 VREF(dp); 876 vput(tdp); 877 vn_lock(dp, 878 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 879 LK_RETRY, ISDOTDOT)); 880 error = nameicap_check_dotdot(ndp, dp); 881 if (error != 0) { 882 #ifdef KTRACE 883 if (KTRPOINT(curthread, KTR_CAPFAIL)) 884 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 885 #endif 886 goto bad; 887 } 888 } 889 } 890 891 /* 892 * We now have a segment name to search for, and a directory to search. 893 */ 894 unionlookup: 895 #ifdef MAC 896 if ((cnp->cn_flags & NOMACCHECK) == 0) { 897 error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, 898 cnp); 899 if (error) 900 goto bad; 901 } 902 #endif 903 ndp->ni_dvp = dp; 904 ndp->ni_vp = NULL; 905 ASSERT_VOP_LOCKED(dp, "lookup"); 906 /* 907 * If we have a shared lock we may need to upgrade the lock for the 908 * last operation. 909 */ 910 if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) && 911 dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED) 912 vn_lock(dp, LK_UPGRADE|LK_RETRY); 913 if ((dp->v_iflag & VI_DOOMED) != 0) { 914 error = ENOENT; 915 goto bad; 916 } 917 /* 918 * If we're looking up the last component and we need an exclusive 919 * lock, adjust our lkflags. 920 */ 921 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) 922 cnp->cn_lkflags = LK_EXCLUSIVE; 923 #ifdef NAMEI_DIAGNOSTIC 924 vn_printf(dp, "lookup in "); 925 #endif 926 lkflags_save = cnp->cn_lkflags; 927 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags, 928 cnp->cn_flags); 929 error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp); 930 cnp->cn_lkflags = lkflags_save; 931 if (error != 0) { 932 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 933 #ifdef NAMEI_DIAGNOSTIC 934 printf("not found\n"); 935 #endif 936 if ((error == ENOENT) && 937 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 938 (dp->v_mount->mnt_flag & MNT_UNION)) { 939 tdp = dp; 940 dp = dp->v_mount->mnt_vnodecovered; 941 VREF(dp); 942 vput(tdp); 943 vn_lock(dp, 944 compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 945 LK_RETRY, cnp->cn_flags)); 946 nameicap_tracker_add(ndp, dp); 947 goto unionlookup; 948 } 949 950 if (error == ERELOOKUP) { 951 vref(dp); 952 ndp->ni_vp = dp; 953 error = 0; 954 relookup = 1; 955 goto good; 956 } 957 958 if (error != EJUSTRETURN) 959 goto bad; 960 /* 961 * At this point, we know we're at the end of the 962 * pathname. If creating / renaming, we can consider 963 * allowing the file or directory to be created / renamed, 964 * provided we're not on a read-only filesystem. 965 */ 966 if (rdonly) { 967 error = EROFS; 968 goto bad; 969 } 970 /* trailing slash only allowed for directories */ 971 if ((cnp->cn_flags & TRAILINGSLASH) && 972 !(cnp->cn_flags & WILLBEDIR)) { 973 error = ENOENT; 974 goto bad; 975 } 976 if ((cnp->cn_flags & LOCKPARENT) == 0) 977 VOP_UNLOCK(dp, 0); 978 /* 979 * We return with ni_vp NULL to indicate that the entry 980 * doesn't currently exist, leaving a pointer to the 981 * (possibly locked) directory vnode in ndp->ni_dvp. 982 */ 983 if (cnp->cn_flags & SAVESTART) { 984 ndp->ni_startdir = ndp->ni_dvp; 985 VREF(ndp->ni_startdir); 986 } 987 goto success; 988 } 989 990 good: 991 #ifdef NAMEI_DIAGNOSTIC 992 printf("found\n"); 993 #endif 994 dp = ndp->ni_vp; 995 996 /* 997 * Check to see if the vnode has been mounted on; 998 * if so find the root of the mounted filesystem. 999 */ 1000 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 1001 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 1002 if (vfs_busy(mp, 0)) 1003 continue; 1004 vput(dp); 1005 if (dp != ndp->ni_dvp) 1006 vput(ndp->ni_dvp); 1007 else 1008 vrele(ndp->ni_dvp); 1009 vrefact(vp_crossmp); 1010 ndp->ni_dvp = vp_crossmp; 1011 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags, 1012 cnp->cn_flags), &tdp); 1013 vfs_unbusy(mp); 1014 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) 1015 panic("vp_crossmp exclusively locked or reclaimed"); 1016 if (error) { 1017 dpunlocked = 1; 1018 goto bad2; 1019 } 1020 ndp->ni_vp = dp = tdp; 1021 } 1022 1023 /* 1024 * Check for symbolic link 1025 */ 1026 if ((dp->v_type == VLNK) && 1027 ((cnp->cn_flags & FOLLOW) || (cnp->cn_flags & TRAILINGSLASH) || 1028 *ndp->ni_next == '/')) { 1029 cnp->cn_flags |= ISSYMLINK; 1030 if (dp->v_iflag & VI_DOOMED) { 1031 /* 1032 * We can't know whether the directory was mounted with 1033 * NOSYMFOLLOW, so we can't follow safely. 1034 */ 1035 error = ENOENT; 1036 goto bad2; 1037 } 1038 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 1039 error = EACCES; 1040 goto bad2; 1041 } 1042 /* 1043 * Symlink code always expects an unlocked dvp. 1044 */ 1045 if (ndp->ni_dvp != ndp->ni_vp) { 1046 VOP_UNLOCK(ndp->ni_dvp, 0); 1047 ni_dvp_unlocked = 1; 1048 } 1049 goto success; 1050 } 1051 1052 nextname: 1053 /* 1054 * Not a symbolic link that we will follow. Continue with the 1055 * next component if there is any; otherwise, we're done. 1056 */ 1057 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 1058 ("lookup: invalid path state.")); 1059 if (relookup) { 1060 relookup = 0; 1061 ndp->ni_pathlen = prev_ni_pathlen; 1062 ndp->ni_next = prev_ni_next; 1063 if (ndp->ni_dvp != dp) 1064 vput(ndp->ni_dvp); 1065 else 1066 vrele(ndp->ni_dvp); 1067 goto dirloop; 1068 } 1069 if (cnp->cn_flags & ISDOTDOT) { 1070 error = nameicap_check_dotdot(ndp, ndp->ni_vp); 1071 if (error != 0) { 1072 #ifdef KTRACE 1073 if (KTRPOINT(curthread, KTR_CAPFAIL)) 1074 ktrcapfail(CAPFAIL_LOOKUP, NULL, NULL); 1075 #endif 1076 goto bad2; 1077 } 1078 } 1079 if (*ndp->ni_next == '/') { 1080 cnp->cn_nameptr = ndp->ni_next; 1081 while (*cnp->cn_nameptr == '/') { 1082 cnp->cn_nameptr++; 1083 ndp->ni_pathlen--; 1084 } 1085 if (ndp->ni_dvp != dp) 1086 vput(ndp->ni_dvp); 1087 else 1088 vrele(ndp->ni_dvp); 1089 goto dirloop; 1090 } 1091 /* 1092 * If we're processing a path with a trailing slash, 1093 * check that the end result is a directory. 1094 */ 1095 if ((cnp->cn_flags & TRAILINGSLASH) && dp->v_type != VDIR) { 1096 error = ENOTDIR; 1097 goto bad2; 1098 } 1099 /* 1100 * Disallow directory write attempts on read-only filesystems. 1101 */ 1102 if (rdonly && 1103 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1104 error = EROFS; 1105 goto bad2; 1106 } 1107 if (cnp->cn_flags & SAVESTART) { 1108 ndp->ni_startdir = ndp->ni_dvp; 1109 VREF(ndp->ni_startdir); 1110 } 1111 if (!wantparent) { 1112 ni_dvp_unlocked = 2; 1113 if (ndp->ni_dvp != dp) 1114 vput(ndp->ni_dvp); 1115 else 1116 vrele(ndp->ni_dvp); 1117 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) { 1118 VOP_UNLOCK(ndp->ni_dvp, 0); 1119 ni_dvp_unlocked = 1; 1120 } 1121 1122 if (cnp->cn_flags & AUDITVNODE1) 1123 AUDIT_ARG_VNODE1(dp); 1124 else if (cnp->cn_flags & AUDITVNODE2) 1125 AUDIT_ARG_VNODE2(dp); 1126 1127 if ((cnp->cn_flags & LOCKLEAF) == 0) 1128 VOP_UNLOCK(dp, 0); 1129 success: 1130 /* 1131 * Because of shared lookup we may have the vnode shared locked, but 1132 * the caller may want it to be exclusively locked. 1133 */ 1134 if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && 1135 VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { 1136 vn_lock(dp, LK_UPGRADE | LK_RETRY); 1137 if (dp->v_iflag & VI_DOOMED) { 1138 error = ENOENT; 1139 goto bad2; 1140 } 1141 } 1142 return (0); 1143 1144 bad2: 1145 if (ni_dvp_unlocked != 2) { 1146 if (dp != ndp->ni_dvp && !ni_dvp_unlocked) 1147 vput(ndp->ni_dvp); 1148 else 1149 vrele(ndp->ni_dvp); 1150 } 1151 bad: 1152 if (!dpunlocked) 1153 vput(dp); 1154 ndp->ni_vp = NULL; 1155 return (error); 1156 } 1157 1158 /* 1159 * relookup - lookup a path name component 1160 * Used by lookup to re-acquire things. 1161 */ 1162 int 1163 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 1164 { 1165 struct vnode *dp = NULL; /* the directory we are searching */ 1166 int wantparent; /* 1 => wantparent or lockparent flag */ 1167 int rdonly; /* lookup read-only flag bit */ 1168 int error = 0; 1169 1170 KASSERT(cnp->cn_flags & ISLASTCN, 1171 ("relookup: Not given last component.")); 1172 /* 1173 * Setup: break out flag bits into variables. 1174 */ 1175 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 1176 KASSERT(wantparent, ("relookup: parent not wanted.")); 1177 rdonly = cnp->cn_flags & RDONLY; 1178 cnp->cn_flags &= ~ISSYMLINK; 1179 dp = dvp; 1180 cnp->cn_lkflags = LK_EXCLUSIVE; 1181 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 1182 1183 /* 1184 * Search a new directory. 1185 * 1186 * The last component of the filename is left accessible via 1187 * cnp->cn_nameptr for callers that need the name. Callers needing 1188 * the name set the SAVENAME flag. When done, they assume 1189 * responsibility for freeing the pathname buffer. 1190 */ 1191 #ifdef NAMEI_DIAGNOSTIC 1192 printf("{%s}: ", cnp->cn_nameptr); 1193 #endif 1194 1195 /* 1196 * Check for "" which represents the root directory after slash 1197 * removal. 1198 */ 1199 if (cnp->cn_nameptr[0] == '\0') { 1200 /* 1201 * Support only LOOKUP for "/" because lookup() 1202 * can't succeed for CREATE, DELETE and RENAME. 1203 */ 1204 KASSERT(cnp->cn_nameiop == LOOKUP, ("nameiop must be LOOKUP")); 1205 KASSERT(dp->v_type == VDIR, ("dp is not a directory")); 1206 1207 if (!(cnp->cn_flags & LOCKLEAF)) 1208 VOP_UNLOCK(dp, 0); 1209 *vpp = dp; 1210 /* XXX This should probably move to the top of function. */ 1211 if (cnp->cn_flags & SAVESTART) 1212 panic("lookup: SAVESTART"); 1213 return (0); 1214 } 1215 1216 if (cnp->cn_flags & ISDOTDOT) 1217 panic ("relookup: lookup on dot-dot"); 1218 1219 /* 1220 * We now have a segment name to search for, and a directory to search. 1221 */ 1222 #ifdef NAMEI_DIAGNOSTIC 1223 vn_printf(dp, "search in "); 1224 #endif 1225 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 1226 KASSERT(*vpp == NULL, ("leaf should be empty")); 1227 if (error != EJUSTRETURN) 1228 goto bad; 1229 /* 1230 * If creating and at end of pathname, then can consider 1231 * allowing file to be created. 1232 */ 1233 if (rdonly) { 1234 error = EROFS; 1235 goto bad; 1236 } 1237 /* ASSERT(dvp == ndp->ni_startdir) */ 1238 if (cnp->cn_flags & SAVESTART) 1239 VREF(dvp); 1240 if ((cnp->cn_flags & LOCKPARENT) == 0) 1241 VOP_UNLOCK(dp, 0); 1242 /* 1243 * We return with ni_vp NULL to indicate that the entry 1244 * doesn't currently exist, leaving a pointer to the 1245 * (possibly locked) directory vnode in ndp->ni_dvp. 1246 */ 1247 return (0); 1248 } 1249 1250 dp = *vpp; 1251 1252 /* 1253 * Disallow directory write attempts on read-only filesystems. 1254 */ 1255 if (rdonly && 1256 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1257 if (dvp == dp) 1258 vrele(dvp); 1259 else 1260 vput(dvp); 1261 error = EROFS; 1262 goto bad; 1263 } 1264 /* 1265 * Set the parent lock/ref state to the requested state. 1266 */ 1267 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { 1268 if (wantparent) 1269 VOP_UNLOCK(dvp, 0); 1270 else 1271 vput(dvp); 1272 } else if (!wantparent) 1273 vrele(dvp); 1274 /* 1275 * Check for symbolic link 1276 */ 1277 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 1278 ("relookup: symlink found.\n")); 1279 1280 /* ASSERT(dvp == ndp->ni_startdir) */ 1281 if (cnp->cn_flags & SAVESTART) 1282 VREF(dvp); 1283 1284 if ((cnp->cn_flags & LOCKLEAF) == 0) 1285 VOP_UNLOCK(dp, 0); 1286 return (0); 1287 bad: 1288 vput(dp); 1289 *vpp = NULL; 1290 return (error); 1291 } 1292 1293 void 1294 NDINIT_ALL(struct nameidata *ndp, u_long op, u_long flags, enum uio_seg segflg, 1295 const char *namep, int dirfd, struct vnode *startdir, cap_rights_t *rightsp, 1296 struct thread *td) 1297 { 1298 1299 ndp->ni_cnd.cn_nameiop = op; 1300 ndp->ni_cnd.cn_flags = flags; 1301 ndp->ni_segflg = segflg; 1302 ndp->ni_dirp = namep; 1303 ndp->ni_dirfd = dirfd; 1304 ndp->ni_startdir = startdir; 1305 filecaps_init(&ndp->ni_filecaps); 1306 ndp->ni_cnd.cn_thread = td; 1307 if (rightsp != NULL) 1308 ndp->ni_rightsneeded = *rightsp; 1309 else 1310 cap_rights_init(&ndp->ni_rightsneeded); 1311 } 1312 1313 /* 1314 * Free data allocated by namei(); see namei(9) for details. 1315 */ 1316 void 1317 NDFREE(struct nameidata *ndp, const u_int flags) 1318 { 1319 int unlock_dvp; 1320 int unlock_vp; 1321 1322 unlock_dvp = 0; 1323 unlock_vp = 0; 1324 1325 if (!(flags & NDF_NO_FREE_PNBUF) && 1326 (ndp->ni_cnd.cn_flags & HASBUF)) { 1327 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 1328 ndp->ni_cnd.cn_flags &= ~HASBUF; 1329 } 1330 if (!(flags & NDF_NO_VP_UNLOCK) && 1331 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 1332 unlock_vp = 1; 1333 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 1334 if (unlock_vp) { 1335 vput(ndp->ni_vp); 1336 unlock_vp = 0; 1337 } else 1338 vrele(ndp->ni_vp); 1339 ndp->ni_vp = NULL; 1340 } 1341 if (unlock_vp) 1342 VOP_UNLOCK(ndp->ni_vp, 0); 1343 if (!(flags & NDF_NO_DVP_UNLOCK) && 1344 (ndp->ni_cnd.cn_flags & LOCKPARENT) && 1345 ndp->ni_dvp != ndp->ni_vp) 1346 unlock_dvp = 1; 1347 if (!(flags & NDF_NO_DVP_RELE) && 1348 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 1349 if (unlock_dvp) { 1350 vput(ndp->ni_dvp); 1351 unlock_dvp = 0; 1352 } else 1353 vrele(ndp->ni_dvp); 1354 ndp->ni_dvp = NULL; 1355 } 1356 if (unlock_dvp) 1357 VOP_UNLOCK(ndp->ni_dvp, 0); 1358 if (!(flags & NDF_NO_STARTDIR_RELE) && 1359 (ndp->ni_cnd.cn_flags & SAVESTART)) { 1360 vrele(ndp->ni_startdir); 1361 ndp->ni_startdir = NULL; 1362 } 1363 } 1364 1365 /* 1366 * Determine if there is a suitable alternate filename under the specified 1367 * prefix for the specified path. If the create flag is set, then the 1368 * alternate prefix will be used so long as the parent directory exists. 1369 * This is used by the various compatibility ABIs so that Linux binaries prefer 1370 * files under /compat/linux for example. The chosen path (whether under 1371 * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1372 * to by pathbuf. The caller is responsible for free'ing the buffer from 1373 * the M_TEMP bucket if one is returned. 1374 */ 1375 int 1376 kern_alternate_path(struct thread *td, const char *prefix, const char *path, 1377 enum uio_seg pathseg, char **pathbuf, int create, int dirfd) 1378 { 1379 struct nameidata nd, ndroot; 1380 char *ptr, *buf, *cp; 1381 size_t len, sz; 1382 int error; 1383 1384 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1385 *pathbuf = buf; 1386 1387 /* Copy the prefix into the new pathname as a starting point. */ 1388 len = strlcpy(buf, prefix, MAXPATHLEN); 1389 if (len >= MAXPATHLEN) { 1390 *pathbuf = NULL; 1391 free(buf, M_TEMP); 1392 return (EINVAL); 1393 } 1394 sz = MAXPATHLEN - len; 1395 ptr = buf + len; 1396 1397 /* Append the filename to the prefix. */ 1398 if (pathseg == UIO_SYSSPACE) 1399 error = copystr(path, ptr, sz, &len); 1400 else 1401 error = copyinstr(path, ptr, sz, &len); 1402 1403 if (error) { 1404 *pathbuf = NULL; 1405 free(buf, M_TEMP); 1406 return (error); 1407 } 1408 1409 /* Only use a prefix with absolute pathnames. */ 1410 if (*ptr != '/') { 1411 error = EINVAL; 1412 goto keeporig; 1413 } 1414 1415 if (dirfd != AT_FDCWD) { 1416 /* 1417 * We want the original because the "prefix" is 1418 * included in the already opened dirfd. 1419 */ 1420 bcopy(ptr, buf, len); 1421 return (0); 1422 } 1423 1424 /* 1425 * We know that there is a / somewhere in this pathname. 1426 * Search backwards for it, to find the file's parent dir 1427 * to see if it exists in the alternate tree. If it does, 1428 * and we want to create a file (cflag is set). We don't 1429 * need to worry about the root comparison in this case. 1430 */ 1431 1432 if (create) { 1433 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1434 *cp = '\0'; 1435 1436 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td); 1437 error = namei(&nd); 1438 *cp = '/'; 1439 if (error != 0) 1440 goto keeporig; 1441 } else { 1442 NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, buf, td); 1443 1444 error = namei(&nd); 1445 if (error != 0) 1446 goto keeporig; 1447 1448 /* 1449 * We now compare the vnode of the prefix to the one 1450 * vnode asked. If they resolve to be the same, then we 1451 * ignore the match so that the real root gets used. 1452 * This avoids the problem of traversing "../.." to find the 1453 * root directory and never finding it, because "/" resolves 1454 * to the emulation root directory. This is expensive :-( 1455 */ 1456 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix, 1457 td); 1458 1459 /* We shouldn't ever get an error from this namei(). */ 1460 error = namei(&ndroot); 1461 if (error == 0) { 1462 if (nd.ni_vp == ndroot.ni_vp) 1463 error = ENOENT; 1464 1465 NDFREE(&ndroot, NDF_ONLY_PNBUF); 1466 vrele(ndroot.ni_vp); 1467 } 1468 } 1469 1470 NDFREE(&nd, NDF_ONLY_PNBUF); 1471 vrele(nd.ni_vp); 1472 1473 keeporig: 1474 /* If there was an error, use the original path name. */ 1475 if (error) 1476 bcopy(ptr, buf, len); 1477 return (error); 1478 } 1479