1 /* $NetBSD: vfs_lookup.c,v 1.200 2012/11/18 17:41:53 manu Exp $ */ 2 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 8.10 (Berkeley) 5/27/95 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.200 2012/11/18 17:41:53 manu Exp $"); 41 42 #include "opt_magiclinks.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kernel.h> 47 #include <sys/syslimits.h> 48 #include <sys/time.h> 49 #include <sys/namei.h> 50 #include <sys/vnode.h> 51 #include <sys/mount.h> 52 #include <sys/errno.h> 53 #include <sys/filedesc.h> 54 #include <sys/hash.h> 55 #include <sys/proc.h> 56 #include <sys/syslog.h> 57 #include <sys/kauth.h> 58 #include <sys/ktrace.h> 59 #include <sys/dirent.h> 60 61 #ifndef MAGICLINKS 62 #define MAGICLINKS 0 63 #endif 64 65 int vfs_magiclinks = MAGICLINKS; 66 67 __CTASSERT(MAXNAMLEN == NAME_MAX); 68 69 /* 70 * Substitute replacement text for 'magic' strings in symlinks. 71 * Returns 0 if successful, and returns non-zero if an error 72 * occurs. (Currently, the only possible error is running out 73 * of temporary pathname space.) 74 * 75 * Looks for "@<string>" and "@<string>/", where <string> is a 76 * recognized 'magic' string. Replaces the "@<string>" with the 77 * appropriate replacement text. (Note that in some cases the 78 * replacement text may have zero length.) 79 * 80 * This would have been table driven, but the variance in 81 * replacement strings (and replacement string lengths) made 82 * that impractical. 83 */ 84 #define VNL(x) \ 85 (sizeof(x) - 1) 86 87 #define VO '{' 88 #define VC '}' 89 90 #define MATCH(str) \ 91 ((termchar == '/' && i + VNL(str) == *len) || \ 92 (i + VNL(str) < *len && \ 93 cp[i + VNL(str)] == termchar)) && \ 94 !strncmp((str), &cp[i], VNL(str)) 95 96 #define SUBSTITUTE(m, s, sl) \ 97 if ((newlen + (sl)) >= MAXPATHLEN) \ 98 return 1; \ 99 i += VNL(m); \ 100 if (termchar != '/') \ 101 i++; \ 102 (void)memcpy(&tmp[newlen], (s), (sl)); \ 103 newlen += (sl); \ 104 change = 1; \ 105 termchar = '/'; 106 107 static int 108 symlink_magic(struct proc *p, char *cp, size_t *len) 109 { 110 char *tmp; 111 size_t change, i, newlen, slen; 112 char termchar = '/'; 113 char idtmp[11]; /* enough for 32 bit *unsigned* integer */ 114 115 116 tmp = PNBUF_GET(); 117 for (change = i = newlen = 0; i < *len; ) { 118 if (cp[i] != '@') { 119 tmp[newlen++] = cp[i++]; 120 continue; 121 } 122 123 i++; 124 125 /* Check for @{var} syntax. */ 126 if (cp[i] == VO) { 127 termchar = VC; 128 i++; 129 } 130 131 /* 132 * The following checks should be ordered according 133 * to frequency of use. 134 */ 135 if (MATCH("machine_arch")) { 136 slen = VNL(MACHINE_ARCH); 137 SUBSTITUTE("machine_arch", MACHINE_ARCH, slen); 138 } else if (MATCH("machine")) { 139 slen = VNL(MACHINE); 140 SUBSTITUTE("machine", MACHINE, slen); 141 } else if (MATCH("hostname")) { 142 SUBSTITUTE("hostname", hostname, hostnamelen); 143 } else if (MATCH("osrelease")) { 144 slen = strlen(osrelease); 145 SUBSTITUTE("osrelease", osrelease, slen); 146 } else if (MATCH("emul")) { 147 slen = strlen(p->p_emul->e_name); 148 SUBSTITUTE("emul", p->p_emul->e_name, slen); 149 } else if (MATCH("kernel_ident")) { 150 slen = strlen(kernel_ident); 151 SUBSTITUTE("kernel_ident", kernel_ident, slen); 152 } else if (MATCH("domainname")) { 153 SUBSTITUTE("domainname", domainname, domainnamelen); 154 } else if (MATCH("ostype")) { 155 slen = strlen(ostype); 156 SUBSTITUTE("ostype", ostype, slen); 157 } else if (MATCH("uid")) { 158 slen = snprintf(idtmp, sizeof(idtmp), "%u", 159 kauth_cred_geteuid(kauth_cred_get())); 160 SUBSTITUTE("uid", idtmp, slen); 161 } else if (MATCH("ruid")) { 162 slen = snprintf(idtmp, sizeof(idtmp), "%u", 163 kauth_cred_getuid(kauth_cred_get())); 164 SUBSTITUTE("ruid", idtmp, slen); 165 } else if (MATCH("gid")) { 166 slen = snprintf(idtmp, sizeof(idtmp), "%u", 167 kauth_cred_getegid(kauth_cred_get())); 168 SUBSTITUTE("gid", idtmp, slen); 169 } else if (MATCH("rgid")) { 170 slen = snprintf(idtmp, sizeof(idtmp), "%u", 171 kauth_cred_getgid(kauth_cred_get())); 172 SUBSTITUTE("rgid", idtmp, slen); 173 } else { 174 tmp[newlen++] = '@'; 175 if (termchar == VC) 176 tmp[newlen++] = VO; 177 } 178 } 179 180 if (change) { 181 (void)memcpy(cp, tmp, newlen); 182 *len = newlen; 183 } 184 PNBUF_PUT(tmp); 185 186 return 0; 187 } 188 189 #undef VNL 190 #undef VO 191 #undef VC 192 #undef MATCH 193 #undef SUBSTITUTE 194 195 //////////////////////////////////////////////////////////// 196 197 /* 198 * Determine the namei hash (for the namecache) for name. 199 * If *ep != NULL, hash from name to ep-1. 200 * If *ep == NULL, hash from name until the first NUL or '/', and 201 * return the location of this termination character in *ep. 202 * 203 * This function returns an equivalent hash to the MI hash32_strn(). 204 * The latter isn't used because in the *ep == NULL case, determining 205 * the length of the string to the first NUL or `/' and then calling 206 * hash32_strn() involves unnecessary double-handling of the data. 207 */ 208 uint32_t 209 namei_hash(const char *name, const char **ep) 210 { 211 uint32_t hash; 212 213 hash = HASH32_STR_INIT; 214 if (*ep != NULL) { 215 for (; name < *ep; name++) 216 hash = hash * 33 + *(const uint8_t *)name; 217 } else { 218 for (; *name != '\0' && *name != '/'; name++) 219 hash = hash * 33 + *(const uint8_t *)name; 220 *ep = name; 221 } 222 return (hash + (hash >> 5)); 223 } 224 225 /* 226 * Find the end of the first path component in NAME and return its 227 * length. 228 */ 229 static size_t 230 namei_getcomponent(const char *name) 231 { 232 size_t pos; 233 234 pos = 0; 235 while (name[pos] != '\0' && name[pos] != '/') { 236 pos++; 237 } 238 return pos; 239 } 240 241 //////////////////////////////////////////////////////////// 242 243 /* 244 * Sealed abstraction for pathnames. 245 * 246 * System-call-layer level code that is going to call namei should 247 * first create a pathbuf and adjust all the bells and whistles on it 248 * as needed by context. 249 */ 250 251 struct pathbuf { 252 char *pb_path; 253 char *pb_pathcopy; 254 unsigned pb_pathcopyuses; 255 }; 256 257 static struct pathbuf * 258 pathbuf_create_raw(void) 259 { 260 struct pathbuf *pb; 261 262 pb = kmem_alloc(sizeof(*pb), KM_SLEEP); 263 if (pb == NULL) { 264 return NULL; 265 } 266 pb->pb_path = PNBUF_GET(); 267 if (pb->pb_path == NULL) { 268 kmem_free(pb, sizeof(*pb)); 269 return NULL; 270 } 271 pb->pb_pathcopy = NULL; 272 pb->pb_pathcopyuses = 0; 273 return pb; 274 } 275 276 void 277 pathbuf_destroy(struct pathbuf *pb) 278 { 279 KASSERT(pb->pb_pathcopyuses == 0); 280 KASSERT(pb->pb_pathcopy == NULL); 281 PNBUF_PUT(pb->pb_path); 282 kmem_free(pb, sizeof(*pb)); 283 } 284 285 struct pathbuf * 286 pathbuf_assimilate(char *pnbuf) 287 { 288 struct pathbuf *pb; 289 290 pb = kmem_alloc(sizeof(*pb), KM_SLEEP); 291 if (pb == NULL) { 292 return NULL; 293 } 294 pb->pb_path = pnbuf; 295 pb->pb_pathcopy = NULL; 296 pb->pb_pathcopyuses = 0; 297 return pb; 298 } 299 300 struct pathbuf * 301 pathbuf_create(const char *path) 302 { 303 struct pathbuf *pb; 304 int error; 305 306 pb = pathbuf_create_raw(); 307 if (pb == NULL) { 308 return NULL; 309 } 310 error = copystr(path, pb->pb_path, PATH_MAX, NULL); 311 if (error != 0) { 312 KASSERT(!"kernel path too long in pathbuf_create"); 313 /* make sure it's null-terminated, just in case */ 314 pb->pb_path[PATH_MAX-1] = '\0'; 315 } 316 return pb; 317 } 318 319 int 320 pathbuf_copyin(const char *userpath, struct pathbuf **ret) 321 { 322 struct pathbuf *pb; 323 int error; 324 325 pb = pathbuf_create_raw(); 326 if (pb == NULL) { 327 return ENOMEM; 328 } 329 error = copyinstr(userpath, pb->pb_path, PATH_MAX, NULL); 330 if (error) { 331 pathbuf_destroy(pb); 332 return error; 333 } 334 *ret = pb; 335 return 0; 336 } 337 338 /* 339 * XXX should not exist: 340 * 1. whether a pointer is kernel or user should be statically checkable. 341 * 2. copyin should be handled by the upper part of the syscall layer, 342 * not in here. 343 */ 344 int 345 pathbuf_maybe_copyin(const char *path, enum uio_seg seg, struct pathbuf **ret) 346 { 347 if (seg == UIO_USERSPACE) { 348 return pathbuf_copyin(path, ret); 349 } else { 350 *ret = pathbuf_create(path); 351 if (*ret == NULL) { 352 return ENOMEM; 353 } 354 return 0; 355 } 356 } 357 358 /* 359 * Get a copy of the path buffer as it currently exists. If this is 360 * called after namei starts the results may be arbitrary. 361 */ 362 void 363 pathbuf_copystring(const struct pathbuf *pb, char *buf, size_t maxlen) 364 { 365 strlcpy(buf, pb->pb_path, maxlen); 366 } 367 368 /* 369 * These two functions allow access to a saved copy of the original 370 * path string. The first copy should be gotten before namei is 371 * called. Each copy that is gotten should be put back. 372 */ 373 374 const char * 375 pathbuf_stringcopy_get(struct pathbuf *pb) 376 { 377 if (pb->pb_pathcopyuses == 0) { 378 pb->pb_pathcopy = PNBUF_GET(); 379 strcpy(pb->pb_pathcopy, pb->pb_path); 380 } 381 pb->pb_pathcopyuses++; 382 return pb->pb_pathcopy; 383 } 384 385 void 386 pathbuf_stringcopy_put(struct pathbuf *pb, const char *str) 387 { 388 KASSERT(str == pb->pb_pathcopy); 389 KASSERT(pb->pb_pathcopyuses > 0); 390 pb->pb_pathcopyuses--; 391 if (pb->pb_pathcopyuses == 0) { 392 PNBUF_PUT(pb->pb_pathcopy); 393 pb->pb_pathcopy = NULL; 394 } 395 } 396 397 398 //////////////////////////////////////////////////////////// 399 400 /* 401 * namei: convert a pathname into a pointer to a (maybe-locked) vnode, 402 * and maybe also its parent directory vnode, and assorted other guff. 403 * See namei(9) for the interface documentation. 404 * 405 * 406 * The FOLLOW flag is set when symbolic links are to be followed 407 * when they occur at the end of the name translation process. 408 * Symbolic links are always followed for all other pathname 409 * components other than the last. 410 * 411 * The segflg defines whether the name is to be copied from user 412 * space or kernel space. 413 * 414 * Overall outline of namei: 415 * 416 * copy in name 417 * get starting directory 418 * while (!done && !error) { 419 * call lookup to search path. 420 * if symbolic link, massage name in buffer and continue 421 * } 422 */ 423 424 /* 425 * Search a pathname. 426 * This is a very central and rather complicated routine. 427 * 428 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 429 * The starting directory is passed in. The pathname is descended 430 * until done, or a symbolic link is encountered. The variable ni_more 431 * is clear if the path is completed; it is set to one if a symbolic 432 * link needing interpretation is encountered. 433 * 434 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 435 * whether the name is to be looked up, created, renamed, or deleted. 436 * When CREATE, RENAME, or DELETE is specified, information usable in 437 * creating, renaming, or deleting a directory entry may be calculated. 438 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 439 * locked. Otherwise the parent directory is not returned. If the target 440 * of the pathname exists and LOCKLEAF is or'ed into the flag the target 441 * is returned locked, otherwise it is returned unlocked. When creating 442 * or renaming and LOCKPARENT is specified, the target may not be ".". 443 * When deleting and LOCKPARENT is specified, the target may be ".". 444 * 445 * Overall outline of lookup: 446 * 447 * dirloop: 448 * identify next component of name at ndp->ni_ptr 449 * handle degenerate case where name is null string 450 * if .. and crossing mount points and on mounted filesys, find parent 451 * call VOP_LOOKUP routine for next component name 452 * directory vnode returned in ni_dvp, locked. 453 * component vnode returned in ni_vp (if it exists), locked. 454 * if result vnode is mounted on and crossing mount points, 455 * find mounted on vnode 456 * if more components of name, do next level at dirloop 457 * return the answer in ni_vp, locked if LOCKLEAF set 458 * if LOCKPARENT set, return locked parent in ni_dvp 459 */ 460 461 462 /* 463 * Internal state for a namei operation. 464 * 465 * cnp is always equal to &ndp->ni_cnp. 466 */ 467 struct namei_state { 468 struct nameidata *ndp; 469 struct componentname *cnp; 470 471 int docache; /* == 0 do not cache last component */ 472 int rdonly; /* lookup read-only flag bit */ 473 int slashes; 474 475 unsigned attempt_retry:1; /* true if error allows emul retry */ 476 }; 477 478 479 /* 480 * Initialize the namei working state. 481 */ 482 static void 483 namei_init(struct namei_state *state, struct nameidata *ndp) 484 { 485 state->ndp = ndp; 486 state->cnp = &ndp->ni_cnd; 487 KASSERT((state->cnp->cn_flags & INRELOOKUP) == 0); 488 489 state->docache = 0; 490 state->rdonly = 0; 491 state->slashes = 0; 492 493 #ifdef DIAGNOSTIC 494 if (!state->cnp->cn_cred) 495 panic("namei: bad cred/proc"); 496 if (state->cnp->cn_nameiop & (~OPMASK)) 497 panic("namei: nameiop contaminated with flags"); 498 if (state->cnp->cn_flags & OPMASK) 499 panic("namei: flags contaminated with nameiops"); 500 #endif 501 502 /* 503 * The buffer for name translation shall be the one inside the 504 * pathbuf. 505 */ 506 state->ndp->ni_pnbuf = state->ndp->ni_pathbuf->pb_path; 507 } 508 509 /* 510 * Clean up the working namei state, leaving things ready for return 511 * from namei. 512 */ 513 static void 514 namei_cleanup(struct namei_state *state) 515 { 516 KASSERT(state->cnp == &state->ndp->ni_cnd); 517 518 /* nothing for now */ 519 (void)state; 520 } 521 522 ////////////////////////////// 523 524 /* 525 * Get the directory context. 526 * Initializes the rootdir and erootdir state and returns a reference 527 * to the starting dir. 528 */ 529 static struct vnode * 530 namei_getstartdir(struct namei_state *state) 531 { 532 struct nameidata *ndp = state->ndp; 533 struct componentname *cnp = state->cnp; 534 struct cwdinfo *cwdi; /* pointer to cwd state */ 535 struct lwp *self = curlwp; /* thread doing namei() */ 536 struct vnode *rootdir, *erootdir, *curdir, *startdir; 537 538 cwdi = self->l_proc->p_cwdi; 539 rw_enter(&cwdi->cwdi_lock, RW_READER); 540 541 /* root dir */ 542 if (cwdi->cwdi_rdir == NULL || (cnp->cn_flags & NOCHROOT)) { 543 rootdir = rootvnode; 544 } else { 545 rootdir = cwdi->cwdi_rdir; 546 } 547 548 /* emulation root dir, if any */ 549 if ((cnp->cn_flags & TRYEMULROOT) == 0) { 550 /* if we don't want it, don't fetch it */ 551 erootdir = NULL; 552 } else if (cnp->cn_flags & EMULROOTSET) { 553 /* explicitly set emulroot; "/../" doesn't override this */ 554 erootdir = ndp->ni_erootdir; 555 } else if (!strncmp(ndp->ni_pnbuf, "/../", 4)) { 556 /* explicit reference to real rootdir */ 557 erootdir = NULL; 558 } else { 559 /* may be null */ 560 erootdir = cwdi->cwdi_edir; 561 } 562 563 /* current dir */ 564 curdir = cwdi->cwdi_cdir; 565 566 if (ndp->ni_pnbuf[0] != '/') { 567 if (ndp->ni_atdir != NULL) { 568 startdir = ndp->ni_atdir; 569 } else { 570 startdir = curdir; 571 } 572 erootdir = NULL; 573 } else if (cnp->cn_flags & TRYEMULROOT && erootdir != NULL) { 574 startdir = erootdir; 575 } else { 576 startdir = rootdir; 577 erootdir = NULL; 578 } 579 580 state->ndp->ni_rootdir = rootdir; 581 state->ndp->ni_erootdir = erootdir; 582 583 /* 584 * Get a reference to the start dir so we can safely unlock cwdi. 585 * 586 * XXX: should we hold references to rootdir and erootdir while 587 * we're running? What happens if a multithreaded process chroots 588 * during namei? 589 */ 590 vref(startdir); 591 592 rw_exit(&cwdi->cwdi_lock); 593 return startdir; 594 } 595 596 /* 597 * Get the directory context for the nfsd case, in parallel to 598 * getstartdir. Initializes the rootdir and erootdir state and 599 * returns a reference to the passed-in starting dir. 600 */ 601 static struct vnode * 602 namei_getstartdir_for_nfsd(struct namei_state *state) 603 { 604 KASSERT(state->ndp->ni_atdir != NULL); 605 606 /* always use the real root, and never set an emulation root */ 607 state->ndp->ni_rootdir = rootvnode; 608 state->ndp->ni_erootdir = NULL; 609 610 vref(state->ndp->ni_atdir); 611 return state->ndp->ni_atdir; 612 } 613 614 615 /* 616 * Ktrace the namei operation. 617 */ 618 static void 619 namei_ktrace(struct namei_state *state) 620 { 621 struct nameidata *ndp = state->ndp; 622 struct componentname *cnp = state->cnp; 623 struct lwp *self = curlwp; /* thread doing namei() */ 624 const char *emul_path; 625 626 if (ktrpoint(KTR_NAMEI)) { 627 if (ndp->ni_erootdir != NULL) { 628 /* 629 * To make any sense, the trace entry need to have the 630 * text of the emulation path prepended. 631 * Usually we can get this from the current process, 632 * but when called from emul_find_interp() it is only 633 * in the exec_package - so we get it passed in ni_next 634 * (this is a hack). 635 */ 636 if (cnp->cn_flags & EMULROOTSET) 637 emul_path = ndp->ni_next; 638 else 639 emul_path = self->l_proc->p_emul->e_path; 640 ktrnamei2(emul_path, strlen(emul_path), 641 ndp->ni_pnbuf, ndp->ni_pathlen); 642 } else 643 ktrnamei(ndp->ni_pnbuf, ndp->ni_pathlen); 644 } 645 } 646 647 /* 648 * Start up namei. Find the root dir and cwd, establish the starting 649 * directory for lookup, and lock it. Also calls ktrace when 650 * appropriate. 651 */ 652 static int 653 namei_start(struct namei_state *state, int isnfsd, 654 struct vnode **startdir_ret) 655 { 656 struct nameidata *ndp = state->ndp; 657 struct vnode *startdir; 658 659 /* length includes null terminator (was originally from copyinstr) */ 660 ndp->ni_pathlen = strlen(ndp->ni_pnbuf) + 1; 661 662 /* 663 * POSIX.1 requirement: "" is not a valid file name. 664 */ 665 if (ndp->ni_pathlen == 1) { 666 return ENOENT; 667 } 668 669 ndp->ni_loopcnt = 0; 670 671 /* Get starting directory, set up root, and ktrace. */ 672 if (isnfsd) { 673 startdir = namei_getstartdir_for_nfsd(state); 674 /* no ktrace */ 675 } else { 676 startdir = namei_getstartdir(state); 677 namei_ktrace(state); 678 } 679 680 /* NDAT may feed us with a non directory namei_getstartdir */ 681 if (startdir->v_type != VDIR) 682 return ENOTDIR; 683 684 vn_lock(startdir, LK_EXCLUSIVE | LK_RETRY); 685 686 *startdir_ret = startdir; 687 return 0; 688 } 689 690 /* 691 * Check for being at a symlink that we're going to follow. 692 */ 693 static inline int 694 namei_atsymlink(struct namei_state *state, struct vnode *foundobj) 695 { 696 return (foundobj->v_type == VLNK) && 697 (state->cnp->cn_flags & (FOLLOW|REQUIREDIR)); 698 } 699 700 /* 701 * Follow a symlink. 702 * 703 * Updates searchdir. inhibitmagic causes magic symlinks to not be 704 * interpreted; this is used by nfsd. 705 * 706 * Unlocks foundobj on success (ugh) 707 */ 708 static inline int 709 namei_follow(struct namei_state *state, int inhibitmagic, 710 struct vnode *searchdir, struct vnode *foundobj, 711 struct vnode **newsearchdir_ret) 712 { 713 struct nameidata *ndp = state->ndp; 714 struct componentname *cnp = state->cnp; 715 716 struct lwp *self = curlwp; /* thread doing namei() */ 717 struct iovec aiov; /* uio for reading symbolic links */ 718 struct uio auio; 719 char *cp; /* pointer into pathname argument */ 720 size_t linklen; 721 int error; 722 723 KASSERT(VOP_ISLOCKED(searchdir) == LK_EXCLUSIVE); 724 KASSERT(VOP_ISLOCKED(foundobj) == LK_EXCLUSIVE); 725 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 726 return ELOOP; 727 } 728 if (foundobj->v_mount->mnt_flag & MNT_SYMPERM) { 729 error = VOP_ACCESS(foundobj, VEXEC, cnp->cn_cred); 730 if (error != 0) 731 return error; 732 } 733 734 /* FUTURE: fix this to not use a second buffer */ 735 cp = PNBUF_GET(); 736 aiov.iov_base = cp; 737 aiov.iov_len = MAXPATHLEN; 738 auio.uio_iov = &aiov; 739 auio.uio_iovcnt = 1; 740 auio.uio_offset = 0; 741 auio.uio_rw = UIO_READ; 742 auio.uio_resid = MAXPATHLEN; 743 UIO_SETUP_SYSSPACE(&auio); 744 error = VOP_READLINK(foundobj, &auio, cnp->cn_cred); 745 if (error) { 746 PNBUF_PUT(cp); 747 return error; 748 } 749 linklen = MAXPATHLEN - auio.uio_resid; 750 if (linklen == 0) { 751 PNBUF_PUT(cp); 752 return ENOENT; 753 } 754 755 /* 756 * Do symlink substitution, if appropriate, and 757 * check length for potential overflow. 758 * 759 * Inhibit symlink substitution for nfsd. 760 * XXX: This is how it was before; is that a bug or a feature? 761 */ 762 if ((!inhibitmagic && vfs_magiclinks && 763 symlink_magic(self->l_proc, cp, &linklen)) || 764 (linklen + ndp->ni_pathlen >= MAXPATHLEN)) { 765 PNBUF_PUT(cp); 766 return ENAMETOOLONG; 767 } 768 if (ndp->ni_pathlen > 1) { 769 /* includes a null-terminator */ 770 memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen); 771 } else { 772 cp[linklen] = '\0'; 773 } 774 ndp->ni_pathlen += linklen; 775 memcpy(ndp->ni_pnbuf, cp, ndp->ni_pathlen); 776 PNBUF_PUT(cp); 777 778 /* we're now starting from the beginning of the buffer again */ 779 cnp->cn_nameptr = ndp->ni_pnbuf; 780 781 /* must unlock this before relocking searchdir */ 782 VOP_UNLOCK(foundobj); 783 784 /* 785 * Check if root directory should replace current directory. 786 */ 787 if (ndp->ni_pnbuf[0] == '/') { 788 vput(searchdir); 789 /* Keep absolute symbolic links inside emulation root */ 790 searchdir = ndp->ni_erootdir; 791 if (searchdir == NULL || 792 (ndp->ni_pnbuf[1] == '.' 793 && ndp->ni_pnbuf[2] == '.' 794 && ndp->ni_pnbuf[3] == '/')) { 795 ndp->ni_erootdir = NULL; 796 searchdir = ndp->ni_rootdir; 797 } 798 vref(searchdir); 799 vn_lock(searchdir, LK_EXCLUSIVE | LK_RETRY); 800 while (cnp->cn_nameptr[0] == '/') { 801 cnp->cn_nameptr++; 802 ndp->ni_pathlen--; 803 } 804 } 805 806 *newsearchdir_ret = searchdir; 807 KASSERT(VOP_ISLOCKED(searchdir) == LK_EXCLUSIVE); 808 return 0; 809 } 810 811 ////////////////////////////// 812 813 /* 814 * Inspect the leading path component and update the state accordingly. 815 */ 816 static int 817 lookup_parsepath(struct namei_state *state) 818 { 819 const char *cp; /* pointer into pathname argument */ 820 821 struct componentname *cnp = state->cnp; 822 struct nameidata *ndp = state->ndp; 823 824 KASSERT(cnp == &ndp->ni_cnd); 825 826 /* 827 * Search a new directory. 828 * 829 * The last component of the filename is left accessible via 830 * cnp->cn_nameptr for callers that need the name. Callers needing 831 * the name set the SAVENAME flag. When done, they assume 832 * responsibility for freeing the pathname buffer. 833 * 834 * At this point, our only vnode state is that the search dir 835 * is held and locked. 836 */ 837 cnp->cn_consume = 0; 838 cnp->cn_namelen = namei_getcomponent(cnp->cn_nameptr); 839 cp = cnp->cn_nameptr + cnp->cn_namelen; 840 if (cnp->cn_namelen > KERNEL_NAME_MAX) { 841 return ENAMETOOLONG; 842 } 843 #ifdef NAMEI_DIAGNOSTIC 844 { char c = *cp; 845 *(char *)cp = '\0'; 846 printf("{%s}: ", cnp->cn_nameptr); 847 *(char *)cp = c; } 848 #endif /* NAMEI_DIAGNOSTIC */ 849 ndp->ni_pathlen -= cnp->cn_namelen; 850 ndp->ni_next = cp; 851 /* 852 * If this component is followed by a slash, then move the pointer to 853 * the next component forward, and remember that this component must be 854 * a directory. 855 */ 856 if (*cp == '/') { 857 do { 858 cp++; 859 } while (*cp == '/'); 860 state->slashes = cp - ndp->ni_next; 861 ndp->ni_pathlen -= state->slashes; 862 ndp->ni_next = cp; 863 cnp->cn_flags |= REQUIREDIR; 864 } else { 865 state->slashes = 0; 866 cnp->cn_flags &= ~REQUIREDIR; 867 } 868 /* 869 * We do special processing on the last component, whether or not it's 870 * a directory. Cache all intervening lookups, but not the final one. 871 */ 872 if (*cp == '\0') { 873 if (state->docache) 874 cnp->cn_flags |= MAKEENTRY; 875 else 876 cnp->cn_flags &= ~MAKEENTRY; 877 cnp->cn_flags |= ISLASTCN; 878 } else { 879 cnp->cn_flags |= MAKEENTRY; 880 cnp->cn_flags &= ~ISLASTCN; 881 } 882 if (cnp->cn_namelen == 2 && 883 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 884 cnp->cn_flags |= ISDOTDOT; 885 else 886 cnp->cn_flags &= ~ISDOTDOT; 887 888 return 0; 889 } 890 891 /* 892 * Call VOP_LOOKUP for a single lookup; return a new search directory 893 * (used when crossing mountpoints up or searching union mounts down) and 894 * the found object, which for create operations may be NULL on success. 895 */ 896 static int 897 lookup_once(struct namei_state *state, 898 struct vnode *searchdir, 899 struct vnode **newsearchdir_ret, 900 struct vnode **foundobj_ret) 901 { 902 struct vnode *tmpvn; /* scratch vnode */ 903 struct vnode *foundobj; /* result */ 904 struct mount *mp; /* mount table entry */ 905 struct lwp *l = curlwp; 906 int error; 907 908 struct componentname *cnp = state->cnp; 909 struct nameidata *ndp = state->ndp; 910 911 KASSERT(cnp == &ndp->ni_cnd); 912 KASSERT(VOP_ISLOCKED(searchdir) == LK_EXCLUSIVE); 913 *newsearchdir_ret = searchdir; 914 915 /* 916 * Handle "..": two special cases. 917 * 1. If at root directory (e.g. after chroot) 918 * or at absolute root directory 919 * then ignore it so can't get out. 920 * 1a. If at the root of the emulation filesystem go to the real 921 * root. So "/../<path>" is always absolute. 922 * 1b. If we have somehow gotten out of a jail, warn 923 * and also ignore it so we can't get farther out. 924 * 2. If this vnode is the root of a mounted 925 * filesystem, then replace it with the 926 * vnode which was mounted on so we take the 927 * .. in the other file system. 928 */ 929 if (cnp->cn_flags & ISDOTDOT) { 930 struct proc *p = l->l_proc; 931 932 for (;;) { 933 if (searchdir == ndp->ni_rootdir || 934 searchdir == rootvnode) { 935 foundobj = searchdir; 936 vref(foundobj); 937 *foundobj_ret = foundobj; 938 error = 0; 939 goto done; 940 } 941 if (ndp->ni_rootdir != rootvnode) { 942 int retval; 943 944 VOP_UNLOCK(searchdir); 945 retval = vn_isunder(searchdir, ndp->ni_rootdir, l); 946 vn_lock(searchdir, LK_EXCLUSIVE | LK_RETRY); 947 if (!retval) { 948 /* Oops! We got out of jail! */ 949 log(LOG_WARNING, 950 "chrooted pid %d uid %d (%s) " 951 "detected outside of its chroot\n", 952 p->p_pid, kauth_cred_geteuid(l->l_cred), 953 p->p_comm); 954 /* Put us at the jail root. */ 955 vput(searchdir); 956 searchdir = NULL; 957 foundobj = ndp->ni_rootdir; 958 vref(foundobj); 959 vref(foundobj); 960 vn_lock(foundobj, LK_EXCLUSIVE | LK_RETRY); 961 *newsearchdir_ret = foundobj; 962 *foundobj_ret = foundobj; 963 error = 0; 964 goto done; 965 } 966 } 967 if ((searchdir->v_vflag & VV_ROOT) == 0 || 968 (cnp->cn_flags & NOCROSSMOUNT)) 969 break; 970 tmpvn = searchdir; 971 searchdir = searchdir->v_mount->mnt_vnodecovered; 972 vref(searchdir); 973 vput(tmpvn); 974 vn_lock(searchdir, LK_EXCLUSIVE | LK_RETRY); 975 *newsearchdir_ret = searchdir; 976 } 977 } 978 979 /* 980 * We now have a segment name to search for, and a directory to search. 981 * Our vnode state here is that "searchdir" is held and locked. 982 */ 983 unionlookup: 984 foundobj = NULL; 985 error = VOP_LOOKUP(searchdir, &foundobj, cnp); 986 987 if (error != 0) { 988 #ifdef DIAGNOSTIC 989 if (foundobj != NULL) 990 panic("leaf `%s' should be empty", cnp->cn_nameptr); 991 #endif /* DIAGNOSTIC */ 992 #ifdef NAMEI_DIAGNOSTIC 993 printf("not found\n"); 994 #endif /* NAMEI_DIAGNOSTIC */ 995 if ((error == ENOENT) && 996 (searchdir->v_vflag & VV_ROOT) && 997 (searchdir->v_mount->mnt_flag & MNT_UNION)) { 998 tmpvn = searchdir; 999 searchdir = searchdir->v_mount->mnt_vnodecovered; 1000 vref(searchdir); 1001 vput(tmpvn); 1002 vn_lock(searchdir, LK_EXCLUSIVE | LK_RETRY); 1003 *newsearchdir_ret = searchdir; 1004 goto unionlookup; 1005 } 1006 1007 if (error != EJUSTRETURN) 1008 goto done; 1009 1010 /* 1011 * If this was not the last component, or there were trailing 1012 * slashes, and we are not going to create a directory, 1013 * then the name must exist. 1014 */ 1015 if ((cnp->cn_flags & (REQUIREDIR | CREATEDIR)) == REQUIREDIR) { 1016 error = ENOENT; 1017 goto done; 1018 } 1019 1020 /* 1021 * If creating and at end of pathname, then can consider 1022 * allowing file to be created. 1023 */ 1024 if (state->rdonly) { 1025 error = EROFS; 1026 goto done; 1027 } 1028 1029 /* 1030 * We return success and a NULL foundobj to indicate 1031 * that the entry doesn't currently exist, leaving a 1032 * pointer to the (normally, locked) directory vnode 1033 * as searchdir. 1034 */ 1035 *foundobj_ret = NULL; 1036 error = 0; 1037 goto done; 1038 } 1039 #ifdef NAMEI_DIAGNOSTIC 1040 printf("found\n"); 1041 #endif /* NAMEI_DIAGNOSTIC */ 1042 1043 /* 1044 * Take into account any additional components consumed by the 1045 * underlying filesystem. This will include any trailing slashes after 1046 * the last component consumed. 1047 */ 1048 if (cnp->cn_consume > 0) { 1049 ndp->ni_pathlen -= cnp->cn_consume - state->slashes; 1050 ndp->ni_next += cnp->cn_consume - state->slashes; 1051 cnp->cn_consume = 0; 1052 if (ndp->ni_next[0] == '\0') 1053 cnp->cn_flags |= ISLASTCN; 1054 } 1055 1056 /* 1057 * "foundobj" and "searchdir" are both locked and held, 1058 * and may be the same vnode. 1059 */ 1060 1061 /* 1062 * Check to see if the vnode has been mounted on; 1063 * if so find the root of the mounted file system. 1064 */ 1065 while (foundobj->v_type == VDIR && 1066 (mp = foundobj->v_mountedhere) != NULL && 1067 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 1068 error = vfs_busy(mp, NULL); 1069 if (error != 0) { 1070 if (searchdir != foundobj) { 1071 vput(foundobj); 1072 } else { 1073 vrele(foundobj); 1074 } 1075 goto done; 1076 } 1077 if (searchdir != foundobj) { 1078 VOP_UNLOCK(searchdir); 1079 } 1080 vput(foundobj); 1081 error = VFS_ROOT(mp, &foundobj); 1082 vfs_unbusy(mp, false, NULL); 1083 if (error) { 1084 vn_lock(searchdir, LK_EXCLUSIVE | LK_RETRY); 1085 goto done; 1086 } 1087 /* 1088 * avoid locking vnodes from two filesystems because it's 1089 * prune to deadlock. eg. when using puffs. 1090 * also, it isn't a good idea to propagate slowness of a 1091 * filesystem up to the root directory. 1092 * for now, only handle the common case. (ie. foundobj is VDIR) 1093 */ 1094 if (foundobj->v_type == VDIR) { 1095 vrele(searchdir); 1096 *newsearchdir_ret = searchdir = foundobj; 1097 vref(searchdir); 1098 } else { 1099 VOP_UNLOCK(foundobj); 1100 vn_lock(searchdir, LK_EXCLUSIVE | LK_RETRY); 1101 vn_lock(foundobj, LK_EXCLUSIVE | LK_RETRY); 1102 } 1103 } 1104 1105 *foundobj_ret = foundobj; 1106 error = 0; 1107 done: 1108 KASSERT(VOP_ISLOCKED(*newsearchdir_ret) == LK_EXCLUSIVE); 1109 /* 1110 * *foundobj_ret is valid only if error == 0. 1111 */ 1112 KASSERT(error != 0 || *foundobj_ret == NULL || 1113 VOP_ISLOCKED(*foundobj_ret) == LK_EXCLUSIVE); 1114 return error; 1115 } 1116 1117 ////////////////////////////// 1118 1119 /* 1120 * Do a complete path search from a single root directory. 1121 * (This is called up to twice if TRYEMULROOT is in effect.) 1122 */ 1123 static int 1124 namei_oneroot(struct namei_state *state, 1125 int neverfollow, int inhibitmagic, int isnfsd) 1126 { 1127 struct nameidata *ndp = state->ndp; 1128 struct componentname *cnp = state->cnp; 1129 struct vnode *searchdir, *foundobj; 1130 int error; 1131 1132 error = namei_start(state, isnfsd, &searchdir); 1133 if (error) { 1134 ndp->ni_dvp = NULL; 1135 ndp->ni_vp = NULL; 1136 return error; 1137 } 1138 KASSERT(searchdir->v_type == VDIR); 1139 1140 /* 1141 * Setup: break out flag bits into variables. 1142 */ 1143 state->docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 1144 if (cnp->cn_nameiop == DELETE) 1145 state->docache = 0; 1146 state->rdonly = cnp->cn_flags & RDONLY; 1147 1148 /* 1149 * Keep going until we run out of path components. 1150 */ 1151 cnp->cn_nameptr = ndp->ni_pnbuf; 1152 1153 /* drop leading slashes (already used them to choose startdir) */ 1154 while (cnp->cn_nameptr[0] == '/') { 1155 cnp->cn_nameptr++; 1156 ndp->ni_pathlen--; 1157 } 1158 /* was it just "/"? */ 1159 if (cnp->cn_nameptr[0] == '\0') { 1160 foundobj = searchdir; 1161 searchdir = NULL; 1162 cnp->cn_flags |= ISLASTCN; 1163 1164 /* bleh */ 1165 goto skiploop; 1166 } 1167 1168 for (;;) { 1169 1170 /* 1171 * If the directory we're on is unmounted, bail out. 1172 * XXX: should this also check if it's unlinked? 1173 * XXX: yes it should... but how? 1174 */ 1175 if (searchdir->v_mount == NULL) { 1176 vput(searchdir); 1177 ndp->ni_dvp = NULL; 1178 ndp->ni_vp = NULL; 1179 return (ENOENT); 1180 } 1181 1182 /* 1183 * Look up the next path component. 1184 * (currently, this may consume more than one) 1185 */ 1186 1187 /* There should be no slashes here. */ 1188 KASSERT(cnp->cn_nameptr[0] != '/'); 1189 1190 /* and we shouldn't have looped around if we were done */ 1191 KASSERT(cnp->cn_nameptr[0] != '\0'); 1192 1193 error = lookup_parsepath(state); 1194 if (error) { 1195 vput(searchdir); 1196 ndp->ni_dvp = NULL; 1197 ndp->ni_vp = NULL; 1198 state->attempt_retry = 1; 1199 return (error); 1200 } 1201 1202 error = lookup_once(state, searchdir, &searchdir, &foundobj); 1203 if (error) { 1204 vput(searchdir); 1205 ndp->ni_dvp = NULL; 1206 ndp->ni_vp = NULL; 1207 /* 1208 * Note that if we're doing TRYEMULROOT we can 1209 * retry with the normal root. Where this is 1210 * currently set matches previous practice, 1211 * but the previous practice didn't make much 1212 * sense and somebody should sit down and 1213 * figure out which cases should cause retry 1214 * and which shouldn't. XXX. 1215 */ 1216 state->attempt_retry = 1; 1217 return (error); 1218 } 1219 1220 if (foundobj == NULL) { 1221 /* 1222 * Success with no object returned means we're 1223 * creating something and it isn't already 1224 * there. Break out of the main loop now so 1225 * the code below doesn't have to test for 1226 * foundobj == NULL. 1227 */ 1228 break; 1229 } 1230 1231 /* 1232 * Check for symbolic link. If we've reached one, 1233 * follow it, unless we aren't supposed to. Back up 1234 * over any slashes that we skipped, as we will need 1235 * them again. 1236 */ 1237 if (namei_atsymlink(state, foundobj)) { 1238 ndp->ni_pathlen += state->slashes; 1239 ndp->ni_next -= state->slashes; 1240 if (neverfollow) { 1241 error = EINVAL; 1242 } else { 1243 /* 1244 * dholland 20110410: if we're at a 1245 * union mount it might make sense to 1246 * use the top of the union stack here 1247 * rather than the layer we found the 1248 * symlink in. (FUTURE) 1249 */ 1250 error = namei_follow(state, inhibitmagic, 1251 searchdir, foundobj, 1252 &searchdir); 1253 } 1254 if (error) { 1255 KASSERT(searchdir != foundobj); 1256 vput(searchdir); 1257 vput(foundobj); 1258 ndp->ni_dvp = NULL; 1259 ndp->ni_vp = NULL; 1260 return error; 1261 } 1262 /* namei_follow unlocks it (ugh) so rele, not put */ 1263 vrele(foundobj); 1264 foundobj = NULL; 1265 1266 /* 1267 * If we followed a symlink to `/' and there 1268 * are no more components after the symlink, 1269 * we're done with the loop and what we found 1270 * is the searchdir. 1271 */ 1272 if (cnp->cn_nameptr[0] == '\0') { 1273 foundobj = searchdir; 1274 searchdir = NULL; 1275 cnp->cn_flags |= ISLASTCN; 1276 break; 1277 } 1278 1279 continue; 1280 } 1281 1282 /* 1283 * Not a symbolic link. 1284 * 1285 * Check for directory, if the component was 1286 * followed by a series of slashes. 1287 */ 1288 if ((foundobj->v_type != VDIR) && 1289 (cnp->cn_flags & REQUIREDIR)) { 1290 if (searchdir == foundobj) { 1291 vrele(searchdir); 1292 } else { 1293 vput(searchdir); 1294 } 1295 vput(foundobj); 1296 ndp->ni_dvp = NULL; 1297 ndp->ni_vp = NULL; 1298 state->attempt_retry = 1; 1299 return ENOTDIR; 1300 } 1301 1302 /* 1303 * Stop if we've reached the last component. 1304 */ 1305 if (cnp->cn_flags & ISLASTCN) { 1306 break; 1307 } 1308 1309 /* 1310 * Continue with the next component. 1311 */ 1312 cnp->cn_nameptr = ndp->ni_next; 1313 if (searchdir == foundobj) { 1314 vrele(searchdir); 1315 } else { 1316 vput(searchdir); 1317 } 1318 searchdir = foundobj; 1319 foundobj = NULL; 1320 } 1321 1322 skiploop: 1323 1324 if (foundobj != NULL) { 1325 if (foundobj == ndp->ni_erootdir) { 1326 /* 1327 * We are about to return the emulation root. 1328 * This isn't a good idea because code might 1329 * repeatedly lookup ".." until the file 1330 * matches that returned for "/" and loop 1331 * forever. So convert it to the real root. 1332 */ 1333 if (searchdir != NULL) { 1334 if (searchdir == foundobj) 1335 vrele(searchdir); 1336 else 1337 vput(searchdir); 1338 searchdir = NULL; 1339 } 1340 vput(foundobj); 1341 foundobj = ndp->ni_rootdir; 1342 vref(foundobj); 1343 vn_lock(foundobj, LK_EXCLUSIVE | LK_RETRY); 1344 } 1345 1346 /* 1347 * If the caller requested the parent node (i.e. it's 1348 * a CREATE, DELETE, or RENAME), and we don't have one 1349 * (because this is the root directory, or we crossed 1350 * a mount point), then we must fail. 1351 */ 1352 if (cnp->cn_nameiop != LOOKUP && 1353 (searchdir == NULL || 1354 searchdir->v_mount != foundobj->v_mount)) { 1355 if (searchdir) { 1356 vput(searchdir); 1357 } 1358 vput(foundobj); 1359 foundobj = NULL; 1360 ndp->ni_dvp = NULL; 1361 ndp->ni_vp = NULL; 1362 state->attempt_retry = 1; 1363 1364 switch (cnp->cn_nameiop) { 1365 case CREATE: 1366 return EEXIST; 1367 case DELETE: 1368 case RENAME: 1369 return EBUSY; 1370 default: 1371 break; 1372 } 1373 panic("Invalid nameiop\n"); 1374 } 1375 1376 /* 1377 * Disallow directory write attempts on read-only lookups. 1378 * Prefers EEXIST over EROFS for the CREATE case. 1379 */ 1380 if (state->rdonly && 1381 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1382 if (searchdir) { 1383 if (foundobj != searchdir) { 1384 vput(searchdir); 1385 } else { 1386 vrele(searchdir); 1387 } 1388 searchdir = NULL; 1389 } 1390 vput(foundobj); 1391 foundobj = NULL; 1392 ndp->ni_dvp = NULL; 1393 ndp->ni_vp = NULL; 1394 state->attempt_retry = 1; 1395 return EROFS; 1396 } 1397 if ((cnp->cn_flags & LOCKLEAF) == 0) { 1398 /* 1399 * Note: if LOCKPARENT but not LOCKLEAF is 1400 * set, and searchdir == foundobj, this code 1401 * necessarily unlocks the parent as well as 1402 * the leaf. That is, just because you specify 1403 * LOCKPARENT doesn't mean you necessarily get 1404 * a locked parent vnode. The code in 1405 * vfs_syscalls.c, and possibly elsewhere, 1406 * that uses this combination "knows" this, so 1407 * it can't be safely changed. Feh. XXX 1408 */ 1409 VOP_UNLOCK(foundobj); 1410 } 1411 } 1412 1413 /* 1414 * Done. 1415 */ 1416 1417 /* 1418 * If LOCKPARENT is not set, the parent directory isn't returned. 1419 */ 1420 if ((cnp->cn_flags & LOCKPARENT) == 0 && searchdir != NULL) { 1421 if (searchdir == foundobj) { 1422 vrele(searchdir); 1423 } else { 1424 vput(searchdir); 1425 } 1426 searchdir = NULL; 1427 } 1428 1429 ndp->ni_dvp = searchdir; 1430 ndp->ni_vp = foundobj; 1431 return 0; 1432 } 1433 1434 /* 1435 * Do namei; wrapper layer that handles TRYEMULROOT. 1436 */ 1437 static int 1438 namei_tryemulroot(struct namei_state *state, 1439 int neverfollow, int inhibitmagic, int isnfsd) 1440 { 1441 int error; 1442 1443 struct nameidata *ndp = state->ndp; 1444 struct componentname *cnp = state->cnp; 1445 const char *savepath = NULL; 1446 1447 KASSERT(cnp == &ndp->ni_cnd); 1448 1449 if (cnp->cn_flags & TRYEMULROOT) { 1450 savepath = pathbuf_stringcopy_get(ndp->ni_pathbuf); 1451 } 1452 1453 emul_retry: 1454 state->attempt_retry = 0; 1455 1456 error = namei_oneroot(state, neverfollow, inhibitmagic, isnfsd); 1457 if (error) { 1458 /* 1459 * Once namei has started up, the existence of ni_erootdir 1460 * tells us whether we're working from an emulation root. 1461 * The TRYEMULROOT flag isn't necessarily authoritative. 1462 */ 1463 if (ndp->ni_erootdir != NULL && state->attempt_retry) { 1464 /* Retry the whole thing using the normal root */ 1465 cnp->cn_flags &= ~TRYEMULROOT; 1466 state->attempt_retry = 0; 1467 1468 /* kinda gross */ 1469 strcpy(ndp->ni_pathbuf->pb_path, savepath); 1470 pathbuf_stringcopy_put(ndp->ni_pathbuf, savepath); 1471 savepath = NULL; 1472 1473 goto emul_retry; 1474 } 1475 } 1476 if (savepath != NULL) { 1477 pathbuf_stringcopy_put(ndp->ni_pathbuf, savepath); 1478 } 1479 return error; 1480 } 1481 1482 /* 1483 * External interface. 1484 */ 1485 int 1486 namei(struct nameidata *ndp) 1487 { 1488 struct namei_state state; 1489 int error; 1490 1491 namei_init(&state, ndp); 1492 error = namei_tryemulroot(&state, 1493 0/*!neverfollow*/, 0/*!inhibitmagic*/, 1494 0/*isnfsd*/); 1495 namei_cleanup(&state); 1496 1497 if (error) { 1498 /* make sure no stray refs leak out */ 1499 KASSERT(ndp->ni_dvp == NULL); 1500 KASSERT(ndp->ni_vp == NULL); 1501 } 1502 1503 return error; 1504 } 1505 1506 //////////////////////////////////////////////////////////// 1507 1508 /* 1509 * External interface used by nfsd. This is basically different from 1510 * namei only in that it has the ability to pass in the "current 1511 * directory", and uses an extra flag "neverfollow" for which there's 1512 * no physical flag defined in namei.h. (There used to be a cut&paste 1513 * copy of about half of namei in nfsd to allow these minor 1514 * adjustments to exist.) 1515 * 1516 * XXX: the namei interface should be adjusted so nfsd can just use 1517 * ordinary namei(). 1518 */ 1519 int 1520 lookup_for_nfsd(struct nameidata *ndp, struct vnode *forcecwd, int neverfollow) 1521 { 1522 struct namei_state state; 1523 int error; 1524 1525 KASSERT(ndp->ni_atdir == NULL); 1526 ndp->ni_atdir = forcecwd; 1527 1528 namei_init(&state, ndp); 1529 error = namei_tryemulroot(&state, 1530 neverfollow, 1/*inhibitmagic*/, 1/*isnfsd*/); 1531 namei_cleanup(&state); 1532 1533 if (error) { 1534 /* make sure no stray refs leak out */ 1535 KASSERT(ndp->ni_dvp == NULL); 1536 KASSERT(ndp->ni_vp == NULL); 1537 } 1538 1539 return error; 1540 } 1541 1542 /* 1543 * A second external interface used by nfsd. This turns out to be a 1544 * single lookup used by the WebNFS code (ha!) to get "index.html" or 1545 * equivalent when asked for a directory. It should eventually evolve 1546 * into some kind of namei_once() call; for the time being it's kind 1547 * of a mess. XXX. 1548 * 1549 * dholland 20110109: I don't think it works, and I don't think it 1550 * worked before I started hacking and slashing either, and I doubt 1551 * anyone will ever notice. 1552 */ 1553 1554 /* 1555 * Internals. This calls lookup_once() after setting up the assorted 1556 * pieces of state the way they ought to be. 1557 */ 1558 static int 1559 do_lookup_for_nfsd_index(struct namei_state *state) 1560 { 1561 int error = 0; 1562 1563 struct componentname *cnp = state->cnp; 1564 struct nameidata *ndp = state->ndp; 1565 struct vnode *startdir; 1566 struct vnode *foundobj; 1567 const char *cp; /* pointer into pathname argument */ 1568 1569 KASSERT(cnp == &ndp->ni_cnd); 1570 1571 startdir = state->ndp->ni_atdir; 1572 1573 cnp->cn_nameptr = ndp->ni_pnbuf; 1574 state->docache = 1; 1575 state->rdonly = cnp->cn_flags & RDONLY; 1576 ndp->ni_dvp = NULL; 1577 1578 cnp->cn_consume = 0; 1579 cnp->cn_namelen = namei_getcomponent(cnp->cn_nameptr); 1580 cp = cnp->cn_nameptr + cnp->cn_namelen; 1581 KASSERT(cnp->cn_namelen <= KERNEL_NAME_MAX); 1582 ndp->ni_pathlen -= cnp->cn_namelen; 1583 ndp->ni_next = cp; 1584 state->slashes = 0; 1585 cnp->cn_flags &= ~REQUIREDIR; 1586 cnp->cn_flags |= MAKEENTRY|ISLASTCN; 1587 1588 if (cnp->cn_namelen == 2 && 1589 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 1590 cnp->cn_flags |= ISDOTDOT; 1591 else 1592 cnp->cn_flags &= ~ISDOTDOT; 1593 1594 /* 1595 * Because lookup_once can change the startdir, we need our 1596 * own reference to it to avoid consuming the caller's. 1597 */ 1598 vref(startdir); 1599 vn_lock(startdir, LK_EXCLUSIVE | LK_RETRY); 1600 error = lookup_once(state, startdir, &startdir, &foundobj); 1601 if (error == 0 && startdir == foundobj) { 1602 vrele(startdir); 1603 } else { 1604 vput(startdir); 1605 } 1606 if (error) { 1607 goto bad; 1608 } 1609 ndp->ni_vp = foundobj; 1610 1611 if (foundobj == NULL) { 1612 return 0; 1613 } 1614 1615 KASSERT((cnp->cn_flags & LOCKPARENT) == 0); 1616 if ((cnp->cn_flags & LOCKLEAF) == 0) { 1617 VOP_UNLOCK(foundobj); 1618 } 1619 return (0); 1620 1621 bad: 1622 ndp->ni_vp = NULL; 1623 return (error); 1624 } 1625 1626 /* 1627 * External interface. The partitioning between this function and the 1628 * above isn't very clear - the above function exists mostly so code 1629 * that uses "state->" can be shuffled around without having to change 1630 * it to "state.". 1631 */ 1632 int 1633 lookup_for_nfsd_index(struct nameidata *ndp, struct vnode *startdir) 1634 { 1635 struct namei_state state; 1636 int error; 1637 1638 KASSERT(ndp->ni_atdir == NULL); 1639 ndp->ni_atdir = startdir; 1640 1641 /* 1642 * Note: the name sent in here (is not|should not be) allowed 1643 * to contain a slash. 1644 */ 1645 if (strlen(ndp->ni_pathbuf->pb_path) > KERNEL_NAME_MAX) { 1646 return ENAMETOOLONG; 1647 } 1648 if (strchr(ndp->ni_pathbuf->pb_path, '/')) { 1649 return EINVAL; 1650 } 1651 1652 ndp->ni_pathlen = strlen(ndp->ni_pathbuf->pb_path) + 1; 1653 ndp->ni_pnbuf = NULL; 1654 ndp->ni_cnd.cn_nameptr = NULL; 1655 1656 namei_init(&state, ndp); 1657 error = do_lookup_for_nfsd_index(&state); 1658 namei_cleanup(&state); 1659 1660 return error; 1661 } 1662 1663 //////////////////////////////////////////////////////////// 1664 1665 /* 1666 * Reacquire a path name component. 1667 * dvp is locked on entry and exit. 1668 * *vpp is locked on exit unless it's NULL. 1669 */ 1670 int 1671 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, int dummy) 1672 { 1673 int rdonly; /* lookup read-only flag bit */ 1674 int error = 0; 1675 #ifdef DEBUG 1676 size_t newlen; /* DEBUG: check name len */ 1677 const char *cp; /* DEBUG: check name ptr */ 1678 #endif /* DEBUG */ 1679 1680 (void)dummy; 1681 1682 /* 1683 * Setup: break out flag bits into variables. 1684 */ 1685 rdonly = cnp->cn_flags & RDONLY; 1686 1687 /* 1688 * Search a new directory. 1689 * 1690 * The cn_hash value is for use by vfs_cache. 1691 * The last component of the filename is left accessible via 1692 * cnp->cn_nameptr for callers that need the name. Callers needing 1693 * the name set the SAVENAME flag. When done, they assume 1694 * responsibility for freeing the pathname buffer. 1695 */ 1696 #ifdef DEBUG 1697 #if 0 1698 cp = NULL; 1699 newhash = namei_hash(cnp->cn_nameptr, &cp); 1700 if ((uint32_t)newhash != (uint32_t)cnp->cn_hash) 1701 panic("relookup: bad hash"); 1702 #endif 1703 newlen = namei_getcomponent(cnp->cn_nameptr); 1704 if (cnp->cn_namelen != newlen) 1705 panic("relookup: bad len"); 1706 cp = cnp->cn_nameptr + cnp->cn_namelen; 1707 while (*cp == '/') 1708 cp++; 1709 if (*cp != 0) 1710 panic("relookup: not last component"); 1711 #endif /* DEBUG */ 1712 1713 /* 1714 * Check for degenerate name (e.g. / or "") 1715 * which is a way of talking about a directory, 1716 * e.g. like "/." or ".". 1717 */ 1718 if (cnp->cn_nameptr[0] == '\0') 1719 panic("relookup: null name"); 1720 1721 if (cnp->cn_flags & ISDOTDOT) 1722 panic("relookup: lookup on dot-dot"); 1723 1724 /* 1725 * We now have a segment name to search for, and a directory to search. 1726 */ 1727 *vpp = NULL; 1728 cnp->cn_flags |= INRELOOKUP; 1729 error = VOP_LOOKUP(dvp, vpp, cnp); 1730 cnp->cn_flags &= ~INRELOOKUP; 1731 if ((error) != 0) { 1732 #ifdef DIAGNOSTIC 1733 if (*vpp != NULL) 1734 panic("leaf `%s' should be empty", cnp->cn_nameptr); 1735 #endif 1736 if (error != EJUSTRETURN) 1737 goto bad; 1738 } 1739 1740 #ifdef DIAGNOSTIC 1741 /* 1742 * Check for symbolic link 1743 */ 1744 if (*vpp && (*vpp)->v_type == VLNK && (cnp->cn_flags & FOLLOW)) 1745 panic("relookup: symlink found"); 1746 #endif 1747 1748 /* 1749 * Check for read-only lookups. 1750 */ 1751 if (rdonly && cnp->cn_nameiop != LOOKUP) { 1752 error = EROFS; 1753 if (*vpp) { 1754 vput(*vpp); 1755 } 1756 goto bad; 1757 } 1758 return (0); 1759 1760 bad: 1761 *vpp = NULL; 1762 return (error); 1763 } 1764 1765 /* 1766 * namei_simple - simple forms of namei. 1767 * 1768 * These are wrappers to allow the simple case callers of namei to be 1769 * left alone while everything else changes under them. 1770 */ 1771 1772 /* Flags */ 1773 struct namei_simple_flags_type { 1774 int dummy; 1775 }; 1776 static const struct namei_simple_flags_type ns_nn, ns_nt, ns_fn, ns_ft; 1777 const namei_simple_flags_t NSM_NOFOLLOW_NOEMULROOT = &ns_nn; 1778 const namei_simple_flags_t NSM_NOFOLLOW_TRYEMULROOT = &ns_nt; 1779 const namei_simple_flags_t NSM_FOLLOW_NOEMULROOT = &ns_fn; 1780 const namei_simple_flags_t NSM_FOLLOW_TRYEMULROOT = &ns_ft; 1781 1782 static 1783 int 1784 namei_simple_convert_flags(namei_simple_flags_t sflags) 1785 { 1786 if (sflags == NSM_NOFOLLOW_NOEMULROOT) 1787 return NOFOLLOW | 0; 1788 if (sflags == NSM_NOFOLLOW_TRYEMULROOT) 1789 return NOFOLLOW | TRYEMULROOT; 1790 if (sflags == NSM_FOLLOW_NOEMULROOT) 1791 return FOLLOW | 0; 1792 if (sflags == NSM_FOLLOW_TRYEMULROOT) 1793 return FOLLOW | TRYEMULROOT; 1794 panic("namei_simple_convert_flags: bogus sflags\n"); 1795 return 0; 1796 } 1797 1798 int 1799 namei_simple_kernel(const char *path, namei_simple_flags_t sflags, 1800 struct vnode **vp_ret) 1801 { 1802 return nameiat_simple_kernel(NULL, path, sflags, vp_ret); 1803 } 1804 1805 int 1806 nameiat_simple_kernel(struct vnode *dvp, const char *path, 1807 namei_simple_flags_t sflags, struct vnode **vp_ret) 1808 { 1809 struct nameidata nd; 1810 struct pathbuf *pb; 1811 int err; 1812 1813 pb = pathbuf_create(path); 1814 if (pb == NULL) { 1815 return ENOMEM; 1816 } 1817 1818 NDINIT(&nd, 1819 LOOKUP, 1820 namei_simple_convert_flags(sflags), 1821 pb); 1822 1823 if (dvp != NULL) 1824 NDAT(&nd, dvp); 1825 1826 err = namei(&nd); 1827 if (err != 0) { 1828 pathbuf_destroy(pb); 1829 return err; 1830 } 1831 *vp_ret = nd.ni_vp; 1832 pathbuf_destroy(pb); 1833 return 0; 1834 } 1835 1836 int 1837 namei_simple_user(const char *path, namei_simple_flags_t sflags, 1838 struct vnode **vp_ret) 1839 { 1840 return nameiat_simple_user(NULL, path, sflags, vp_ret); 1841 } 1842 1843 int 1844 nameiat_simple_user(struct vnode *dvp, const char *path, 1845 namei_simple_flags_t sflags, struct vnode **vp_ret) 1846 { 1847 struct pathbuf *pb; 1848 struct nameidata nd; 1849 int err; 1850 1851 err = pathbuf_copyin(path, &pb); 1852 if (err) { 1853 return err; 1854 } 1855 1856 NDINIT(&nd, 1857 LOOKUP, 1858 namei_simple_convert_flags(sflags), 1859 pb); 1860 1861 if (dvp != NULL) 1862 NDAT(&nd, dvp); 1863 1864 err = namei(&nd); 1865 if (err != 0) { 1866 pathbuf_destroy(pb); 1867 return err; 1868 } 1869 *vp_ret = nd.ni_vp; 1870 pathbuf_destroy(pb); 1871 return 0; 1872 } 1873