Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_lookup.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /*- 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "opt_ktrace.h" 41 #include "opt_mac.h" 42 #include "opt_vfs.h" 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/kernel.h> 47 #include <sys/lock.h> 48 #include <sys/mutex.h> 49 #include <sys/namei.h> 50 #include <sys/vnode.h> 51 #include <sys/mount.h> 52 #include <sys/filedesc.h> 53 #include <sys/proc.h> 54 #include <sys/syscallsubr.h> 55 #include <sys/sysctl.h> 56 #ifdef KTRACE 57 #include <sys/ktrace.h> 58 #endif 59 60 #include <security/audit/audit.h> 61 #include <security/mac/mac_framework.h> 62 63 #include <vm/uma.h> 64 65 #define NAMEI_DIAGNOSTIC 1 66 #undef NAMEI_DIAGNOSTIC 67 68 /* 69 * Allocation zone for namei 70 */ 71 uma_zone_t namei_zone; 72 /* 73 * Placeholder vnode for mp traversal 74 */ 75 static struct vnode *vp_crossmp; 76 77 static void 78 nameiinit(void *dummy __unused) 79 { 80 int error; 81 82 namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, 83 UMA_ALIGN_PTR, 0); 84 error = getnewvnode("crossmp", NULL, &dead_vnodeops, &vp_crossmp); 85 if (error != 0) 86 panic("nameiinit: getnewvnode"); 87 vp_crossmp->v_vnlock->lk_flags &= ~LK_NOSHARE; 88 } 89 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); 90 91 #ifdef LOOKUP_SHARED 92 static int lookup_shared = 1; 93 #else 94 static int lookup_shared = 0; 95 #endif 96 SYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &lookup_shared, 0, 97 "Enables/Disables shared locks for path name translation"); 98 99 /* 100 * Convert a pathname into a pointer to a locked vnode. 101 * 102 * The FOLLOW flag is set when symbolic links are to be followed 103 * when they occur at the end of the name translation process. 104 * Symbolic links are always followed for all other pathname 105 * components other than the last. 106 * 107 * The segflg defines whether the name is to be copied from user 108 * space or kernel space. 109 * 110 * Overall outline of namei: 111 * 112 * copy in name 113 * get starting directory 114 * while (!done && !error) { 115 * call lookup to search path. 116 * if symbolic link, massage name in buffer and continue 117 * } 118 */ 119 int 120 namei(struct nameidata *ndp) 121 { 122 struct filedesc *fdp; /* pointer to file descriptor state */ 123 char *cp; /* pointer into pathname argument */ 124 struct vnode *dp; /* the directory we are searching */ 125 struct iovec aiov; /* uio for reading symbolic links */ 126 struct uio auio; 127 int error, linklen; 128 struct componentname *cnp = &ndp->ni_cnd; 129 struct thread *td = cnp->cn_thread; 130 struct proc *p = td->td_proc; 131 int vfslocked; 132 133 KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0, 134 ("NOT MPSAFE and Giant not held")); 135 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; 136 KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc")); 137 KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, 138 ("namei: nameiop contaminated with flags")); 139 KASSERT((cnp->cn_flags & OPMASK) == 0, 140 ("namei: flags contaminated with nameiops")); 141 if (!lookup_shared) 142 cnp->cn_flags &= ~LOCKSHARED; 143 fdp = p->p_fd; 144 145 /* 146 * Get a buffer for the name to be translated, and copy the 147 * name into the buffer. 148 */ 149 if ((cnp->cn_flags & HASBUF) == 0) 150 cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); 151 if (ndp->ni_segflg == UIO_SYSSPACE) 152 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 153 MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 154 else 155 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 156 MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 157 158 /* If we are auditing the kernel pathname, save the user pathname. */ 159 if (cnp->cn_flags & AUDITVNODE1) 160 AUDIT_ARG(upath, td, cnp->cn_pnbuf, ARG_UPATH1); 161 if (cnp->cn_flags & AUDITVNODE2) 162 AUDIT_ARG(upath, td, cnp->cn_pnbuf, ARG_UPATH2); 163 164 /* 165 * Don't allow empty pathnames. 166 */ 167 if (!error && *cnp->cn_pnbuf == '\0') 168 error = ENOENT; 169 170 if (error) { 171 uma_zfree(namei_zone, cnp->cn_pnbuf); 172 #ifdef DIAGNOSTIC 173 cnp->cn_pnbuf = NULL; 174 cnp->cn_nameptr = NULL; 175 #endif 176 ndp->ni_vp = NULL; 177 return (error); 178 } 179 ndp->ni_loopcnt = 0; 180 #ifdef KTRACE 181 if (KTRPOINT(td, KTR_NAMEI)) { 182 KASSERT(cnp->cn_thread == curthread, 183 ("namei not using curthread")); 184 ktrnamei(cnp->cn_pnbuf); 185 } 186 #endif 187 188 /* 189 * Get starting point for the translation. 190 */ 191 FILEDESC_SLOCK(fdp); 192 ndp->ni_rootdir = fdp->fd_rdir; 193 ndp->ni_topdir = fdp->fd_jdir; 194 195 dp = fdp->fd_cdir; 196 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 197 VREF(dp); 198 FILEDESC_SUNLOCK(fdp); 199 for (;;) { 200 /* 201 * Check if root directory should replace current directory. 202 * Done at start of translation and after symbolic link. 203 */ 204 cnp->cn_nameptr = cnp->cn_pnbuf; 205 if (*(cnp->cn_nameptr) == '/') { 206 vrele(dp); 207 VFS_UNLOCK_GIANT(vfslocked); 208 while (*(cnp->cn_nameptr) == '/') { 209 cnp->cn_nameptr++; 210 ndp->ni_pathlen--; 211 } 212 dp = ndp->ni_rootdir; 213 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 214 VREF(dp); 215 } 216 if (vfslocked) 217 ndp->ni_cnd.cn_flags |= GIANTHELD; 218 ndp->ni_startdir = dp; 219 error = lookup(ndp); 220 if (error) { 221 uma_zfree(namei_zone, cnp->cn_pnbuf); 222 #ifdef DIAGNOSTIC 223 cnp->cn_pnbuf = NULL; 224 cnp->cn_nameptr = NULL; 225 #endif 226 return (error); 227 } 228 vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 229 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 230 /* 231 * Check for symbolic link 232 */ 233 if ((cnp->cn_flags & ISSYMLINK) == 0) { 234 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 235 uma_zfree(namei_zone, cnp->cn_pnbuf); 236 #ifdef DIAGNOSTIC 237 cnp->cn_pnbuf = NULL; 238 cnp->cn_nameptr = NULL; 239 #endif 240 } else 241 cnp->cn_flags |= HASBUF; 242 243 if ((cnp->cn_flags & MPSAFE) == 0) { 244 VFS_UNLOCK_GIANT(vfslocked); 245 } else if (vfslocked) 246 ndp->ni_cnd.cn_flags |= GIANTHELD; 247 return (0); 248 } 249 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 250 error = ELOOP; 251 break; 252 } 253 #ifdef MAC 254 if ((cnp->cn_flags & NOMACCHECK) == 0) { 255 error = mac_check_vnode_readlink(td->td_ucred, 256 ndp->ni_vp); 257 if (error) 258 break; 259 } 260 #endif 261 if (ndp->ni_pathlen > 1) 262 cp = uma_zalloc(namei_zone, M_WAITOK); 263 else 264 cp = cnp->cn_pnbuf; 265 aiov.iov_base = cp; 266 aiov.iov_len = MAXPATHLEN; 267 auio.uio_iov = &aiov; 268 auio.uio_iovcnt = 1; 269 auio.uio_offset = 0; 270 auio.uio_rw = UIO_READ; 271 auio.uio_segflg = UIO_SYSSPACE; 272 auio.uio_td = (struct thread *)0; 273 auio.uio_resid = MAXPATHLEN; 274 error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 275 if (error) { 276 if (ndp->ni_pathlen > 1) 277 uma_zfree(namei_zone, cp); 278 break; 279 } 280 linklen = MAXPATHLEN - auio.uio_resid; 281 if (linklen == 0) { 282 if (ndp->ni_pathlen > 1) 283 uma_zfree(namei_zone, cp); 284 error = ENOENT; 285 break; 286 } 287 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 288 if (ndp->ni_pathlen > 1) 289 uma_zfree(namei_zone, cp); 290 error = ENAMETOOLONG; 291 break; 292 } 293 if (ndp->ni_pathlen > 1) { 294 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 295 uma_zfree(namei_zone, cnp->cn_pnbuf); 296 cnp->cn_pnbuf = cp; 297 } else 298 cnp->cn_pnbuf[linklen] = '\0'; 299 ndp->ni_pathlen += linklen; 300 vput(ndp->ni_vp); 301 dp = ndp->ni_dvp; 302 } 303 uma_zfree(namei_zone, cnp->cn_pnbuf); 304 #ifdef DIAGNOSTIC 305 cnp->cn_pnbuf = NULL; 306 cnp->cn_nameptr = NULL; 307 #endif 308 vput(ndp->ni_vp); 309 ndp->ni_vp = NULL; 310 vrele(ndp->ni_dvp); 311 VFS_UNLOCK_GIANT(vfslocked); 312 return (error); 313 } 314 315 static int 316 compute_cn_lkflags(struct mount *mp, int lkflags) 317 { 318 if (mp == NULL || 319 ((lkflags & LK_SHARED) && !(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED))) { 320 lkflags &= ~LK_SHARED; 321 lkflags |= LK_EXCLUSIVE; 322 } 323 return lkflags; 324 } 325 326 /* 327 * Search a pathname. 328 * This is a very central and rather complicated routine. 329 * 330 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 331 * The starting directory is taken from ni_startdir. The pathname is 332 * descended until done, or a symbolic link is encountered. The variable 333 * ni_more is clear if the path is completed; it is set to one if a 334 * symbolic link needing interpretation is encountered. 335 * 336 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 337 * whether the name is to be looked up, created, renamed, or deleted. 338 * When CREATE, RENAME, or DELETE is specified, information usable in 339 * creating, renaming, or deleting a directory entry may be calculated. 340 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 341 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 342 * returned unlocked. Otherwise the parent directory is not returned. If 343 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 344 * the target is returned locked, otherwise it is returned unlocked. 345 * When creating or renaming and LOCKPARENT is specified, the target may not 346 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 347 * 348 * Overall outline of lookup: 349 * 350 * dirloop: 351 * identify next component of name at ndp->ni_ptr 352 * handle degenerate case where name is null string 353 * if .. and crossing mount points and on mounted filesys, find parent 354 * call VOP_LOOKUP routine for next component name 355 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 356 * component vnode returned in ni_vp (if it exists), locked. 357 * if result vnode is mounted on and crossing mount points, 358 * find mounted on vnode 359 * if more components of name, do next level at dirloop 360 * return the answer in ni_vp, locked if LOCKLEAF set 361 * if LOCKPARENT set, return locked parent in ni_dvp 362 * if WANTPARENT set, return unlocked parent in ni_dvp 363 */ 364 int 365 lookup(struct nameidata *ndp) 366 { 367 char *cp; /* pointer into pathname argument */ 368 struct vnode *dp = 0; /* the directory we are searching */ 369 struct vnode *tdp; /* saved dp */ 370 struct mount *mp; /* mount table entry */ 371 int docache; /* == 0 do not cache last component */ 372 int wantparent; /* 1 => wantparent or lockparent flag */ 373 int rdonly; /* lookup read-only flag bit */ 374 int trailing_slash; 375 int error = 0; 376 int dpunlocked = 0; /* dp has already been unlocked */ 377 struct componentname *cnp = &ndp->ni_cnd; 378 struct thread *td = cnp->cn_thread; 379 int vfslocked; /* VFS Giant state for child */ 380 int dvfslocked; /* VFS Giant state for parent */ 381 int tvfslocked; 382 int lkflags_save; 383 384 /* 385 * Setup: break out flag bits into variables. 386 */ 387 dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 388 vfslocked = 0; 389 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 390 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 391 KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 392 ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 393 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 394 if (cnp->cn_nameiop == DELETE || 395 (wantparent && cnp->cn_nameiop != CREATE && 396 cnp->cn_nameiop != LOOKUP)) 397 docache = 0; 398 rdonly = cnp->cn_flags & RDONLY; 399 cnp->cn_flags &= ~ISSYMLINK; 400 ndp->ni_dvp = NULL; 401 /* 402 * We use shared locks until we hit the parent of the last cn then 403 * we adjust based on the requesting flags. 404 */ 405 if (lookup_shared) 406 cnp->cn_lkflags = LK_SHARED; 407 else 408 cnp->cn_lkflags = LK_EXCLUSIVE; 409 dp = ndp->ni_startdir; 410 ndp->ni_startdir = NULLVP; 411 vn_lock(dp, compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY), td); 412 413 dirloop: 414 /* 415 * Search a new directory. 416 * 417 * The last component of the filename is left accessible via 418 * cnp->cn_nameptr for callers that need the name. Callers needing 419 * the name set the SAVENAME flag. When done, they assume 420 * responsibility for freeing the pathname buffer. 421 */ 422 cnp->cn_consume = 0; 423 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 424 continue; 425 cnp->cn_namelen = cp - cnp->cn_nameptr; 426 if (cnp->cn_namelen > NAME_MAX) { 427 error = ENAMETOOLONG; 428 goto bad; 429 } 430 #ifdef NAMEI_DIAGNOSTIC 431 { char c = *cp; 432 *cp = '\0'; 433 printf("{%s}: ", cnp->cn_nameptr); 434 *cp = c; } 435 #endif 436 ndp->ni_pathlen -= cnp->cn_namelen; 437 ndp->ni_next = cp; 438 439 /* 440 * Replace multiple slashes by a single slash and trailing slashes 441 * by a null. This must be done before VOP_LOOKUP() because some 442 * fs's don't know about trailing slashes. Remember if there were 443 * trailing slashes to handle symlinks, existing non-directories 444 * and non-existing files that won't be directories specially later. 445 */ 446 trailing_slash = 0; 447 while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 448 cp++; 449 ndp->ni_pathlen--; 450 if (*cp == '\0') { 451 trailing_slash = 1; 452 *ndp->ni_next = '\0'; /* XXX for direnter() ... */ 453 } 454 } 455 ndp->ni_next = cp; 456 457 cnp->cn_flags |= MAKEENTRY; 458 if (*cp == '\0' && docache == 0) 459 cnp->cn_flags &= ~MAKEENTRY; 460 if (cnp->cn_namelen == 2 && 461 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 462 cnp->cn_flags |= ISDOTDOT; 463 else 464 cnp->cn_flags &= ~ISDOTDOT; 465 if (*ndp->ni_next == 0) 466 cnp->cn_flags |= ISLASTCN; 467 else 468 cnp->cn_flags &= ~ISLASTCN; 469 470 471 /* 472 * Check for degenerate name (e.g. / or "") 473 * which is a way of talking about a directory, 474 * e.g. like "/." or ".". 475 */ 476 if (cnp->cn_nameptr[0] == '\0') { 477 if (dp->v_type != VDIR) { 478 error = ENOTDIR; 479 goto bad; 480 } 481 if (cnp->cn_nameiop != LOOKUP) { 482 error = EISDIR; 483 goto bad; 484 } 485 if (wantparent) { 486 ndp->ni_dvp = dp; 487 VREF(dp); 488 } 489 ndp->ni_vp = dp; 490 491 if (cnp->cn_flags & AUDITVNODE1) 492 AUDIT_ARG(vnode, dp, ARG_VNODE1); 493 else if (cnp->cn_flags & AUDITVNODE2) 494 AUDIT_ARG(vnode, dp, ARG_VNODE2); 495 496 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 497 VOP_UNLOCK(dp, 0, td); 498 /* XXX This should probably move to the top of function. */ 499 if (cnp->cn_flags & SAVESTART) 500 panic("lookup: SAVESTART"); 501 goto success; 502 } 503 504 /* 505 * Handle "..": four special cases. 506 * 1. Return an error if this is the last component of 507 * the name and the operation is DELETE or RENAME. 508 * 2. If at root directory (e.g. after chroot) 509 * or at absolute root directory 510 * then ignore it so can't get out. 511 * 3. If this vnode is the root of a mounted 512 * filesystem, then replace it with the 513 * vnode which was mounted on so we take the 514 * .. in the other filesystem. 515 * 4. If the vnode is the top directory of 516 * the jail or chroot, don't let them out. 517 */ 518 if (cnp->cn_flags & ISDOTDOT) { 519 if ((cnp->cn_flags & ISLASTCN) != 0 && 520 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 521 error = EINVAL; 522 goto bad; 523 } 524 for (;;) { 525 if (dp == ndp->ni_rootdir || 526 dp == ndp->ni_topdir || 527 dp == rootvnode || 528 ((dp->v_vflag & VV_ROOT) != 0 && 529 (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 530 ndp->ni_dvp = dp; 531 ndp->ni_vp = dp; 532 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 533 VREF(dp); 534 goto nextname; 535 } 536 if ((dp->v_vflag & VV_ROOT) == 0) 537 break; 538 if (dp->v_iflag & VI_DOOMED) { /* forced unmount */ 539 error = EBADF; 540 goto bad; 541 } 542 tdp = dp; 543 dp = dp->v_mount->mnt_vnodecovered; 544 tvfslocked = dvfslocked; 545 dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 546 VREF(dp); 547 vput(tdp); 548 VFS_UNLOCK_GIANT(tvfslocked); 549 vn_lock(dp, compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY), td); 550 } 551 } 552 553 /* 554 * We now have a segment name to search for, and a directory to search. 555 */ 556 unionlookup: 557 #ifdef MAC 558 if ((cnp->cn_flags & NOMACCHECK) == 0) { 559 error = mac_check_vnode_lookup(td->td_ucred, dp, cnp); 560 if (error) 561 goto bad; 562 } 563 #endif 564 ndp->ni_dvp = dp; 565 ndp->ni_vp = NULL; 566 ASSERT_VOP_LOCKED(dp, "lookup"); 567 VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked)); 568 /* 569 * If we have a shared lock we may need to upgrade the lock for the 570 * last operation. 571 */ 572 if (dp != vp_crossmp && 573 VOP_ISLOCKED(dp, td) == LK_SHARED && 574 (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT)) 575 vn_lock(dp, LK_UPGRADE|LK_RETRY, td); 576 /* 577 * If we're looking up the last component and we need an exclusive 578 * lock, adjust our lkflags. 579 */ 580 if ((cnp->cn_flags & (ISLASTCN|LOCKSHARED|LOCKLEAF)) == 581 (ISLASTCN|LOCKLEAF)) 582 cnp->cn_lkflags = LK_EXCLUSIVE; 583 #ifdef NAMEI_DIAGNOSTIC 584 vprint("lookup in", dp); 585 #endif 586 lkflags_save = cnp->cn_lkflags; 587 cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags); 588 if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 589 cnp->cn_lkflags = lkflags_save; 590 KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 591 #ifdef NAMEI_DIAGNOSTIC 592 printf("not found\n"); 593 #endif 594 if ((error == ENOENT) && 595 (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 596 (dp->v_mount->mnt_flag & MNT_UNION)) { 597 tdp = dp; 598 dp = dp->v_mount->mnt_vnodecovered; 599 tvfslocked = dvfslocked; 600 dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 601 VREF(dp); 602 vput(tdp); 603 VFS_UNLOCK_GIANT(tvfslocked); 604 vn_lock(dp, compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY), td); 605 goto unionlookup; 606 } 607 608 if (error != EJUSTRETURN) 609 goto bad; 610 /* 611 * If creating and at end of pathname, then can consider 612 * allowing file to be created. 613 */ 614 if (rdonly) { 615 error = EROFS; 616 goto bad; 617 } 618 if (*cp == '\0' && trailing_slash && 619 !(cnp->cn_flags & WILLBEDIR)) { 620 error = ENOENT; 621 goto bad; 622 } 623 if ((cnp->cn_flags & LOCKPARENT) == 0) 624 VOP_UNLOCK(dp, 0, td); 625 /* 626 * This is a temporary assert to make sure I know what the 627 * behavior here was. 628 */ 629 KASSERT((cnp->cn_flags & (WANTPARENT|LOCKPARENT)) != 0, 630 ("lookup: Unhandled case.")); 631 /* 632 * We return with ni_vp NULL to indicate that the entry 633 * doesn't currently exist, leaving a pointer to the 634 * (possibly locked) directory vnode in ndp->ni_dvp. 635 */ 636 if (cnp->cn_flags & SAVESTART) { 637 ndp->ni_startdir = ndp->ni_dvp; 638 VREF(ndp->ni_startdir); 639 } 640 goto success; 641 } else 642 cnp->cn_lkflags = lkflags_save; 643 #ifdef NAMEI_DIAGNOSTIC 644 printf("found\n"); 645 #endif 646 /* 647 * Take into account any additional components consumed by 648 * the underlying filesystem. 649 */ 650 if (cnp->cn_consume > 0) { 651 cnp->cn_nameptr += cnp->cn_consume; 652 ndp->ni_next += cnp->cn_consume; 653 ndp->ni_pathlen -= cnp->cn_consume; 654 cnp->cn_consume = 0; 655 } 656 657 dp = ndp->ni_vp; 658 vfslocked = VFS_LOCK_GIANT(dp->v_mount); 659 660 /* 661 * Check to see if the vnode has been mounted on; 662 * if so find the root of the mounted filesystem. 663 */ 664 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 665 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 666 if (vfs_busy(mp, 0, 0, td)) 667 continue; 668 vput(dp); 669 VFS_UNLOCK_GIANT(vfslocked); 670 vfslocked = VFS_LOCK_GIANT(mp); 671 if (dp != ndp->ni_dvp) 672 vput(ndp->ni_dvp); 673 else 674 vrele(ndp->ni_dvp); 675 VFS_UNLOCK_GIANT(dvfslocked); 676 dvfslocked = 0; 677 vref(vp_crossmp); 678 ndp->ni_dvp = vp_crossmp; 679 error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags), &tdp, td); 680 vfs_unbusy(mp, td); 681 if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT, td)) 682 panic("vp_crossmp exclusively locked or reclaimed"); 683 if (error) { 684 dpunlocked = 1; 685 goto bad2; 686 } 687 ndp->ni_vp = dp = tdp; 688 } 689 690 /* 691 * Check for symbolic link 692 */ 693 if ((dp->v_type == VLNK) && 694 ((cnp->cn_flags & FOLLOW) || trailing_slash || 695 *ndp->ni_next == '/')) { 696 cnp->cn_flags |= ISSYMLINK; 697 if (dp->v_iflag & VI_DOOMED) { 698 /* We can't know whether the directory was mounted with 699 * NOSYMFOLLOW, so we can't follow safely. */ 700 error = EBADF; 701 goto bad2; 702 } 703 if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 704 error = EACCES; 705 goto bad2; 706 } 707 /* 708 * Symlink code always expects an unlocked dvp. 709 */ 710 if (ndp->ni_dvp != ndp->ni_vp) 711 VOP_UNLOCK(ndp->ni_dvp, 0, td); 712 goto success; 713 } 714 715 /* 716 * Check for bogus trailing slashes. 717 */ 718 if (trailing_slash && dp->v_type != VDIR) { 719 error = ENOTDIR; 720 goto bad2; 721 } 722 723 nextname: 724 /* 725 * Not a symbolic link. If more pathname, 726 * continue at next component, else return. 727 */ 728 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 729 ("lookup: invalid path state.")); 730 if (*ndp->ni_next == '/') { 731 cnp->cn_nameptr = ndp->ni_next; 732 while (*cnp->cn_nameptr == '/') { 733 cnp->cn_nameptr++; 734 ndp->ni_pathlen--; 735 } 736 if (ndp->ni_dvp != dp) 737 vput(ndp->ni_dvp); 738 else 739 vrele(ndp->ni_dvp); 740 VFS_UNLOCK_GIANT(dvfslocked); 741 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */ 742 vfslocked = 0; 743 goto dirloop; 744 } 745 /* 746 * Disallow directory write attempts on read-only filesystems. 747 */ 748 if (rdonly && 749 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 750 error = EROFS; 751 goto bad2; 752 } 753 if (cnp->cn_flags & SAVESTART) { 754 ndp->ni_startdir = ndp->ni_dvp; 755 VREF(ndp->ni_startdir); 756 } 757 if (!wantparent) { 758 if (ndp->ni_dvp != dp) 759 vput(ndp->ni_dvp); 760 else 761 vrele(ndp->ni_dvp); 762 VFS_UNLOCK_GIANT(dvfslocked); 763 dvfslocked = 0; 764 } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) 765 VOP_UNLOCK(ndp->ni_dvp, 0, td); 766 767 if (cnp->cn_flags & AUDITVNODE1) 768 AUDIT_ARG(vnode, dp, ARG_VNODE1); 769 else if (cnp->cn_flags & AUDITVNODE2) 770 AUDIT_ARG(vnode, dp, ARG_VNODE2); 771 772 if ((cnp->cn_flags & LOCKLEAF) == 0) 773 VOP_UNLOCK(dp, 0, td); 774 success: 775 /* 776 * Because of lookup_shared we may have the vnode shared locked, but 777 * the caller may want it to be exclusively locked. 778 */ 779 if ((cnp->cn_flags & (ISLASTCN | LOCKSHARED | LOCKLEAF)) == 780 (ISLASTCN | LOCKLEAF) && VOP_ISLOCKED(dp, td) != LK_EXCLUSIVE) { 781 vn_lock(dp, LK_UPGRADE | LK_RETRY, td); 782 } 783 if (vfslocked && dvfslocked) 784 VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */ 785 if (vfslocked || dvfslocked) 786 ndp->ni_cnd.cn_flags |= GIANTHELD; 787 return (0); 788 789 bad2: 790 if (dp != ndp->ni_dvp) 791 vput(ndp->ni_dvp); 792 else 793 vrele(ndp->ni_dvp); 794 bad: 795 if (!dpunlocked) 796 vput(dp); 797 VFS_UNLOCK_GIANT(vfslocked); 798 VFS_UNLOCK_GIANT(dvfslocked); 799 ndp->ni_cnd.cn_flags &= ~GIANTHELD; 800 ndp->ni_vp = NULL; 801 return (error); 802 } 803 804 /* 805 * relookup - lookup a path name component 806 * Used by lookup to re-acquire things. 807 */ 808 int 809 relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 810 { 811 struct thread *td = cnp->cn_thread; 812 struct vnode *dp = 0; /* the directory we are searching */ 813 int wantparent; /* 1 => wantparent or lockparent flag */ 814 int rdonly; /* lookup read-only flag bit */ 815 int error = 0; 816 817 KASSERT(cnp->cn_flags & ISLASTCN, 818 ("relookup: Not given last component.")); 819 /* 820 * Setup: break out flag bits into variables. 821 */ 822 wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 823 KASSERT(wantparent, ("relookup: parent not wanted.")); 824 rdonly = cnp->cn_flags & RDONLY; 825 cnp->cn_flags &= ~ISSYMLINK; 826 dp = dvp; 827 cnp->cn_lkflags = LK_EXCLUSIVE; 828 vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, td); 829 830 /* 831 * Search a new directory. 832 * 833 * The last component of the filename is left accessible via 834 * cnp->cn_nameptr for callers that need the name. Callers needing 835 * the name set the SAVENAME flag. When done, they assume 836 * responsibility for freeing the pathname buffer. 837 */ 838 #ifdef NAMEI_DIAGNOSTIC 839 printf("{%s}: ", cnp->cn_nameptr); 840 #endif 841 842 /* 843 * Check for degenerate name (e.g. / or "") 844 * which is a way of talking about a directory, 845 * e.g. like "/." or ".". 846 */ 847 if (cnp->cn_nameptr[0] == '\0') { 848 if (cnp->cn_nameiop != LOOKUP || wantparent) { 849 error = EISDIR; 850 goto bad; 851 } 852 if (dp->v_type != VDIR) { 853 error = ENOTDIR; 854 goto bad; 855 } 856 if (!(cnp->cn_flags & LOCKLEAF)) 857 VOP_UNLOCK(dp, 0, td); 858 *vpp = dp; 859 /* XXX This should probably move to the top of function. */ 860 if (cnp->cn_flags & SAVESTART) 861 panic("lookup: SAVESTART"); 862 return (0); 863 } 864 865 if (cnp->cn_flags & ISDOTDOT) 866 panic ("relookup: lookup on dot-dot"); 867 868 /* 869 * We now have a segment name to search for, and a directory to search. 870 */ 871 #ifdef NAMEI_DIAGNOSTIC 872 vprint("search in:", dp); 873 #endif 874 if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 875 KASSERT(*vpp == NULL, ("leaf should be empty")); 876 if (error != EJUSTRETURN) 877 goto bad; 878 /* 879 * If creating and at end of pathname, then can consider 880 * allowing file to be created. 881 */ 882 if (rdonly) { 883 error = EROFS; 884 goto bad; 885 } 886 /* ASSERT(dvp == ndp->ni_startdir) */ 887 if (cnp->cn_flags & SAVESTART) 888 VREF(dvp); 889 if ((cnp->cn_flags & LOCKPARENT) == 0) 890 VOP_UNLOCK(dp, 0, td); 891 /* 892 * This is a temporary assert to make sure I know what the 893 * behavior here was. 894 */ 895 KASSERT((cnp->cn_flags & (WANTPARENT|LOCKPARENT)) != 0, 896 ("relookup: Unhandled case.")); 897 /* 898 * We return with ni_vp NULL to indicate that the entry 899 * doesn't currently exist, leaving a pointer to the 900 * (possibly locked) directory vnode in ndp->ni_dvp. 901 */ 902 return (0); 903 } 904 905 dp = *vpp; 906 907 /* 908 * Disallow directory write attempts on read-only filesystems. 909 */ 910 if (rdonly && 911 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 912 if (dvp == dp) 913 vrele(dvp); 914 else 915 vput(dvp); 916 error = EROFS; 917 goto bad; 918 } 919 /* 920 * Set the parent lock/ref state to the requested state. 921 */ 922 if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { 923 if (wantparent) 924 VOP_UNLOCK(dvp, 0, td); 925 else 926 vput(dvp); 927 } else if (!wantparent) 928 vrele(dvp); 929 /* 930 * Check for symbolic link 931 */ 932 KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 933 ("relookup: symlink found.\n")); 934 935 /* ASSERT(dvp == ndp->ni_startdir) */ 936 if (cnp->cn_flags & SAVESTART) 937 VREF(dvp); 938 939 if ((cnp->cn_flags & LOCKLEAF) == 0) 940 VOP_UNLOCK(dp, 0, td); 941 return (0); 942 bad: 943 vput(dp); 944 *vpp = NULL; 945 return (error); 946 } 947 948 /* 949 * Free data allocated by namei(); see namei(9) for details. 950 */ 951 void 952 NDFREE(struct nameidata *ndp, const u_int flags) 953 { 954 int unlock_dvp; 955 int unlock_vp; 956 957 unlock_dvp = 0; 958 unlock_vp = 0; 959 960 if (!(flags & NDF_NO_FREE_PNBUF) && 961 (ndp->ni_cnd.cn_flags & HASBUF)) { 962 uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 963 ndp->ni_cnd.cn_flags &= ~HASBUF; 964 } 965 if (!(flags & NDF_NO_VP_UNLOCK) && 966 (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 967 unlock_vp = 1; 968 if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 969 if (unlock_vp) { 970 vput(ndp->ni_vp); 971 unlock_vp = 0; 972 } else 973 vrele(ndp->ni_vp); 974 ndp->ni_vp = NULL; 975 } 976 if (unlock_vp) 977 VOP_UNLOCK(ndp->ni_vp, 0, ndp->ni_cnd.cn_thread); 978 if (!(flags & NDF_NO_DVP_UNLOCK) && 979 (ndp->ni_cnd.cn_flags & LOCKPARENT) && 980 ndp->ni_dvp != ndp->ni_vp) 981 unlock_dvp = 1; 982 if (!(flags & NDF_NO_DVP_RELE) && 983 (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 984 if (unlock_dvp) { 985 vput(ndp->ni_dvp); 986 unlock_dvp = 0; 987 } else 988 vrele(ndp->ni_dvp); 989 ndp->ni_dvp = NULL; 990 } 991 if (unlock_dvp) 992 VOP_UNLOCK(ndp->ni_dvp, 0, ndp->ni_cnd.cn_thread); 993 if (!(flags & NDF_NO_STARTDIR_RELE) && 994 (ndp->ni_cnd.cn_flags & SAVESTART)) { 995 vrele(ndp->ni_startdir); 996 ndp->ni_startdir = NULL; 997 } 998 } 999 1000 /* 1001 * Determine if there is a suitable alternate filename under the specified 1002 * prefix for the specified path. If the create flag is set, then the 1003 * alternate prefix will be used so long as the parent directory exists. 1004 * This is used by the various compatiblity ABIs so that Linux binaries prefer 1005 * files under /compat/linux for example. The chosen path (whether under 1006 * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1007 * to by pathbuf. The caller is responsible for free'ing the buffer from 1008 * the M_TEMP bucket if one is returned. 1009 */ 1010 int 1011 kern_alternate_path(struct thread *td, const char *prefix, char *path, 1012 enum uio_seg pathseg, char **pathbuf, int create) 1013 { 1014 struct nameidata nd, ndroot; 1015 char *ptr, *buf, *cp; 1016 size_t len, sz; 1017 int error; 1018 1019 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1020 *pathbuf = buf; 1021 1022 /* Copy the prefix into the new pathname as a starting point. */ 1023 len = strlcpy(buf, prefix, MAXPATHLEN); 1024 if (len >= MAXPATHLEN) { 1025 *pathbuf = NULL; 1026 free(buf, M_TEMP); 1027 return (EINVAL); 1028 } 1029 sz = MAXPATHLEN - len; 1030 ptr = buf + len; 1031 1032 /* Append the filename to the prefix. */ 1033 if (pathseg == UIO_SYSSPACE) 1034 error = copystr(path, ptr, sz, &len); 1035 else 1036 error = copyinstr(path, ptr, sz, &len); 1037 1038 if (error) { 1039 *pathbuf = NULL; 1040 free(buf, M_TEMP); 1041 return (error); 1042 } 1043 1044 /* Only use a prefix with absolute pathnames. */ 1045 if (*ptr != '/') { 1046 error = EINVAL; 1047 goto keeporig; 1048 } 1049 1050 /* 1051 * We know that there is a / somewhere in this pathname. 1052 * Search backwards for it, to find the file's parent dir 1053 * to see if it exists in the alternate tree. If it does, 1054 * and we want to create a file (cflag is set). We don't 1055 * need to worry about the root comparison in this case. 1056 */ 1057 1058 if (create) { 1059 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1060 *cp = '\0'; 1061 1062 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1063 error = namei(&nd); 1064 *cp = '/'; 1065 if (error != 0) 1066 goto keeporig; 1067 } else { 1068 NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1069 1070 error = namei(&nd); 1071 if (error != 0) 1072 goto keeporig; 1073 1074 /* 1075 * We now compare the vnode of the prefix to the one 1076 * vnode asked. If they resolve to be the same, then we 1077 * ignore the match so that the real root gets used. 1078 * This avoids the problem of traversing "../.." to find the 1079 * root directory and never finding it, because "/" resolves 1080 * to the emulation root directory. This is expensive :-( 1081 */ 1082 NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix, 1083 td); 1084 1085 /* We shouldn't ever get an error from this namei(). */ 1086 error = namei(&ndroot); 1087 if (error == 0) { 1088 if (nd.ni_vp == ndroot.ni_vp) 1089 error = ENOENT; 1090 1091 NDFREE(&ndroot, NDF_ONLY_PNBUF); 1092 vrele(ndroot.ni_vp); 1093 VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot)); 1094 } 1095 } 1096 1097 NDFREE(&nd, NDF_ONLY_PNBUF); 1098 vrele(nd.ni_vp); 1099 VFS_UNLOCK_GIANT(NDHASGIANT(&nd)); 1100 1101 keeporig: 1102 /* If there was an error, use the original path name. */ 1103 if (error) 1104 bcopy(ptr, buf, len); 1105 return (error); 1106 }
Cache object: bc6dc2dc718c070c70e080550e80a9b1
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]