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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94 39 */ 40 41 #include <sys/param.h> 42 #include <sys/syslimits.h> 43 #include <sys/time.h> 44 #include <sys/namei.h> 45 #include <sys/vnode.h> 46 #include <sys/mount.h> 47 #include <sys/errno.h> 48 #include <sys/malloc.h> 49 #include <sys/filedesc.h> 50 #include <sys/proc.h> 51 52 #ifdef KTRACE 53 #include <sys/ktrace.h> 54 #endif 55 56 /* 57 * Convert a pathname into a pointer to a locked inode. 58 * 59 * The FOLLOW flag is set when symbolic links are to be followed 60 * when they occur at the end of the name translation process. 61 * Symbolic links are always followed for all other pathname 62 * components other than the last. 63 * 64 * The segflg defines whether the name is to be copied from user 65 * space or kernel space. 66 * 67 * Overall outline of namei: 68 * 69 * copy in name 70 * get starting directory 71 * while (!done && !error) { 72 * call lookup to search path. 73 * if symbolic link, massage name in buffer and continue 74 * } 75 */ 76 int 77 namei(ndp) 78 register struct nameidata *ndp; 79 { 80 register struct filedesc *fdp; /* pointer to file descriptor state */ 81 register char *cp; /* pointer into pathname argument */ 82 register struct vnode *dp; /* the directory we are searching */ 83 struct iovec aiov; /* uio for reading symbolic links */ 84 struct uio auio; 85 int error, linklen; 86 struct componentname *cnp = &ndp->ni_cnd; 87 88 ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_proc->p_ucred; 89 #ifdef DIAGNOSTIC 90 if (!cnp->cn_cred || !cnp->cn_proc) 91 panic ("namei: bad cred/proc"); 92 if (cnp->cn_nameiop & (~OPMASK)) 93 panic ("namei: nameiop contaminated with flags"); 94 if (cnp->cn_flags & OPMASK) 95 panic ("namei: flags contaminated with nameiops"); 96 #endif 97 fdp = cnp->cn_proc->p_fd; 98 99 /* 100 * Get a buffer for the name to be translated, and copy the 101 * name into the buffer. 102 */ 103 if ((cnp->cn_flags & HASBUF) == 0) 104 MALLOC(cnp->cn_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK); 105 if (ndp->ni_segflg == UIO_SYSSPACE) 106 error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 107 MAXPATHLEN, &ndp->ni_pathlen); 108 else 109 error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 110 MAXPATHLEN, &ndp->ni_pathlen); 111 if (error) { 112 free(cnp->cn_pnbuf, M_NAMEI); 113 ndp->ni_vp = NULL; 114 return (error); 115 } 116 ndp->ni_loopcnt = 0; 117 #ifdef KTRACE 118 if (KTRPOINT(cnp->cn_proc, KTR_NAMEI)) 119 ktrnamei(cnp->cn_proc->p_tracep, cnp->cn_pnbuf); 120 #endif 121 122 /* 123 * Get starting point for the translation. 124 */ 125 if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL) 126 ndp->ni_rootdir = rootvnode; 127 dp = fdp->fd_cdir; 128 VREF(dp); 129 for (;;) { 130 /* 131 * Check if root directory should replace current directory. 132 * Done at start of translation and after symbolic link. 133 */ 134 cnp->cn_nameptr = cnp->cn_pnbuf; 135 if (*(cnp->cn_nameptr) == '/') { 136 vrele(dp); 137 while (*(cnp->cn_nameptr) == '/') { 138 cnp->cn_nameptr++; 139 ndp->ni_pathlen--; 140 } 141 dp = ndp->ni_rootdir; 142 VREF(dp); 143 } 144 ndp->ni_startdir = dp; 145 if (error = lookup(ndp)) { 146 FREE(cnp->cn_pnbuf, M_NAMEI); 147 return (error); 148 } 149 /* 150 * Check for symbolic link 151 */ 152 if ((cnp->cn_flags & ISSYMLINK) == 0) { 153 if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) 154 FREE(cnp->cn_pnbuf, M_NAMEI); 155 else 156 cnp->cn_flags |= HASBUF; 157 return (0); 158 } 159 if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1) 160 VOP_UNLOCK(ndp->ni_dvp); 161 if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 162 error = ELOOP; 163 break; 164 } 165 if (ndp->ni_pathlen > 1) 166 MALLOC(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK); 167 else 168 cp = cnp->cn_pnbuf; 169 aiov.iov_base = cp; 170 aiov.iov_len = MAXPATHLEN; 171 auio.uio_iov = &aiov; 172 auio.uio_iovcnt = 1; 173 auio.uio_offset = 0; 174 auio.uio_rw = UIO_READ; 175 auio.uio_segflg = UIO_SYSSPACE; 176 auio.uio_procp = (struct proc *)0; 177 auio.uio_resid = MAXPATHLEN; 178 if (error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred)) { 179 if (ndp->ni_pathlen > 1) 180 free(cp, M_NAMEI); 181 break; 182 } 183 linklen = MAXPATHLEN - auio.uio_resid; 184 if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 185 if (ndp->ni_pathlen > 1) 186 free(cp, M_NAMEI); 187 error = ENAMETOOLONG; 188 break; 189 } 190 if (ndp->ni_pathlen > 1) { 191 bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 192 FREE(cnp->cn_pnbuf, M_NAMEI); 193 cnp->cn_pnbuf = cp; 194 } else 195 cnp->cn_pnbuf[linklen] = '\0'; 196 ndp->ni_pathlen += linklen; 197 vput(ndp->ni_vp); 198 dp = ndp->ni_dvp; 199 } 200 FREE(cnp->cn_pnbuf, M_NAMEI); 201 vrele(ndp->ni_dvp); 202 vput(ndp->ni_vp); 203 ndp->ni_vp = NULL; 204 return (error); 205 } 206 207 /* 208 * Search a pathname. 209 * This is a very central and rather complicated routine. 210 * 211 * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 212 * The starting directory is taken from ni_startdir. The pathname is 213 * descended until done, or a symbolic link is encountered. The variable 214 * ni_more is clear if the path is completed; it is set to one if a 215 * symbolic link needing interpretation is encountered. 216 * 217 * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 218 * whether the name is to be looked up, created, renamed, or deleted. 219 * When CREATE, RENAME, or DELETE is specified, information usable in 220 * creating, renaming, or deleting a directory entry may be calculated. 221 * If flag has LOCKPARENT or'ed into it, the parent directory is returned 222 * locked. If flag has WANTPARENT or'ed into it, the parent directory is 223 * returned unlocked. Otherwise the parent directory is not returned. If 224 * the target of the pathname exists and LOCKLEAF is or'ed into the flag 225 * the target is returned locked, otherwise it is returned unlocked. 226 * When creating or renaming and LOCKPARENT is specified, the target may not 227 * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 228 * 229 * Overall outline of lookup: 230 * 231 * dirloop: 232 * identify next component of name at ndp->ni_ptr 233 * handle degenerate case where name is null string 234 * if .. and crossing mount points and on mounted filesys, find parent 235 * call VOP_LOOKUP routine for next component name 236 * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 237 * component vnode returned in ni_vp (if it exists), locked. 238 * if result vnode is mounted on and crossing mount points, 239 * find mounted on vnode 240 * if more components of name, do next level at dirloop 241 * return the answer in ni_vp, locked if LOCKLEAF set 242 * if LOCKPARENT set, return locked parent in ni_dvp 243 * if WANTPARENT set, return unlocked parent in ni_dvp 244 */ 245 int 246 lookup(ndp) 247 register struct nameidata *ndp; 248 { 249 register char *cp; /* pointer into pathname argument */ 250 register struct vnode *dp = 0; /* the directory we are searching */ 251 struct vnode *tdp; /* saved dp */ 252 struct mount *mp; /* mount table entry */ 253 int docache; /* == 0 do not cache last component */ 254 int wantparent; /* 1 => wantparent or lockparent flag */ 255 int rdonly; /* lookup read-only flag bit */ 256 int error = 0; 257 struct componentname *cnp = &ndp->ni_cnd; 258 259 /* 260 * Setup: break out flag bits into variables. 261 */ 262 wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 263 docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 264 if (cnp->cn_nameiop == DELETE || 265 (wantparent && cnp->cn_nameiop != CREATE)) 266 docache = 0; 267 rdonly = cnp->cn_flags & RDONLY; 268 ndp->ni_dvp = NULL; 269 cnp->cn_flags &= ~ISSYMLINK; 270 dp = ndp->ni_startdir; 271 ndp->ni_startdir = NULLVP; 272 VOP_LOCK(dp); 273 274 dirloop: 275 /* 276 * Search a new directory. 277 * 278 * The cn_hash value is for use by vfs_cache. 279 * The last component of the filename is left accessible via 280 * cnp->cn_nameptr for callers that need the name. Callers needing 281 * the name set the SAVENAME flag. When done, they assume 282 * responsibility for freeing the pathname buffer. 283 */ 284 cnp->cn_consume = 0; 285 cnp->cn_hash = 0; 286 for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 287 cnp->cn_hash += (unsigned char)*cp; 288 cnp->cn_namelen = cp - cnp->cn_nameptr; 289 if (cnp->cn_namelen > NAME_MAX) { 290 error = ENAMETOOLONG; 291 goto bad; 292 } 293 #ifdef NAMEI_DIAGNOSTIC 294 { char c = *cp; 295 *cp = '\0'; 296 printf("{%s}: ", cnp->cn_nameptr); 297 *cp = c; } 298 #endif 299 ndp->ni_pathlen -= cnp->cn_namelen; 300 ndp->ni_next = cp; 301 cnp->cn_flags |= MAKEENTRY; 302 if (*cp == '\0' && docache == 0) 303 cnp->cn_flags &= ~MAKEENTRY; 304 if (cnp->cn_namelen == 2 && 305 cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 306 cnp->cn_flags |= ISDOTDOT; 307 else 308 cnp->cn_flags &= ~ISDOTDOT; 309 if (*ndp->ni_next == 0) 310 cnp->cn_flags |= ISLASTCN; 311 else 312 cnp->cn_flags &= ~ISLASTCN; 313 314 315 /* 316 * Check for degenerate name (e.g. / or "") 317 * which is a way of talking about a directory, 318 * e.g. like "/." or ".". 319 */ 320 if (cnp->cn_nameptr[0] == '\0') { 321 if (cnp->cn_nameiop != LOOKUP) { 322 error = EISDIR; 323 goto bad; 324 } 325 if (dp->v_type != VDIR) { 326 error = ENOTDIR; 327 goto bad; 328 } 329 if (wantparent) { 330 ndp->ni_dvp = dp; 331 VREF(dp); 332 } 333 ndp->ni_vp = dp; 334 if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 335 VOP_UNLOCK(dp); 336 if (cnp->cn_flags & SAVESTART) 337 panic("lookup: SAVESTART"); 338 return (0); 339 } 340 341 /* 342 * Handle "..": two special cases. 343 * 1. If at root directory (e.g. after chroot) 344 * or at absolute root directory 345 * then ignore it so can't get out. 346 * 2. If this vnode is the root of a mounted 347 * filesystem, then replace it with the 348 * vnode which was mounted on so we take the 349 * .. in the other file system. 350 */ 351 if (cnp->cn_flags & ISDOTDOT) { 352 for (;;) { 353 if (dp == ndp->ni_rootdir || dp == rootvnode) { 354 ndp->ni_dvp = dp; 355 ndp->ni_vp = dp; 356 VREF(dp); 357 goto nextname; 358 } 359 if ((dp->v_flag & VROOT) == 0 || 360 (cnp->cn_flags & NOCROSSMOUNT)) 361 break; 362 tdp = dp; 363 dp = dp->v_mount->mnt_vnodecovered; 364 vput(tdp); 365 VREF(dp); 366 VOP_LOCK(dp); 367 } 368 } 369 370 /* 371 * We now have a segment name to search for, and a directory to search. 372 */ 373 unionlookup: 374 ndp->ni_dvp = dp; 375 if (error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) { 376 #ifdef DIAGNOSTIC 377 if (ndp->ni_vp != NULL) 378 panic("leaf should be empty"); 379 #endif 380 #ifdef NAMEI_DIAGNOSTIC 381 printf("not found\n"); 382 #endif 383 if ((error == ENOENT) && 384 (dp->v_flag & VROOT) && 385 (dp->v_mount->mnt_flag & MNT_UNION)) { 386 tdp = dp; 387 dp = dp->v_mount->mnt_vnodecovered; 388 vput(tdp); 389 VREF(dp); 390 VOP_LOCK(dp); 391 goto unionlookup; 392 } 393 394 if (error != EJUSTRETURN) 395 goto bad; 396 /* 397 * If creating and at end of pathname, then can consider 398 * allowing file to be created. 399 */ 400 if (rdonly || (ndp->ni_dvp->v_mount->mnt_flag & MNT_RDONLY)) { 401 error = EROFS; 402 goto bad; 403 } 404 /* 405 * We return with ni_vp NULL to indicate that the entry 406 * doesn't currently exist, leaving a pointer to the 407 * (possibly locked) directory inode in ndp->ni_dvp. 408 */ 409 if (cnp->cn_flags & SAVESTART) { 410 ndp->ni_startdir = ndp->ni_dvp; 411 VREF(ndp->ni_startdir); 412 } 413 return (0); 414 } 415 #ifdef NAMEI_DIAGNOSTIC 416 printf("found\n"); 417 #endif 418 419 /* 420 * Take into account any additional components consumed by 421 * the underlying filesystem. 422 */ 423 if (cnp->cn_consume > 0) { 424 cnp->cn_nameptr += cnp->cn_consume; 425 ndp->ni_next += cnp->cn_consume; 426 ndp->ni_pathlen -= cnp->cn_consume; 427 cnp->cn_consume = 0; 428 } 429 430 dp = ndp->ni_vp; 431 /* 432 * Check for symbolic link 433 */ 434 if ((dp->v_type == VLNK) && 435 ((cnp->cn_flags & FOLLOW) || *ndp->ni_next == '/')) { 436 cnp->cn_flags |= ISSYMLINK; 437 return (0); 438 } 439 440 /* 441 * Check to see if the vnode has been mounted on; 442 * if so find the root of the mounted file system. 443 */ 444 while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 445 (cnp->cn_flags & NOCROSSMOUNT) == 0) { 446 if (mp->mnt_flag & MNT_MLOCK) { 447 mp->mnt_flag |= MNT_MWAIT; 448 sleep((caddr_t)mp, PVFS); 449 continue; 450 } 451 if (error = VFS_ROOT(dp->v_mountedhere, &tdp)) 452 goto bad2; 453 vput(dp); 454 ndp->ni_vp = dp = tdp; 455 } 456 457 nextname: 458 /* 459 * Not a symbolic link. If more pathname, 460 * continue at next component, else return. 461 */ 462 if (*ndp->ni_next == '/') { 463 cnp->cn_nameptr = ndp->ni_next; 464 while (*cnp->cn_nameptr == '/') { 465 cnp->cn_nameptr++; 466 ndp->ni_pathlen--; 467 } 468 vrele(ndp->ni_dvp); 469 goto dirloop; 470 } 471 /* 472 * Check for read-only file systems. 473 */ 474 if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) { 475 /* 476 * Disallow directory write attempts on read-only 477 * file systems. 478 */ 479 if (rdonly || (dp->v_mount->mnt_flag & MNT_RDONLY) || 480 (wantparent && 481 (ndp->ni_dvp->v_mount->mnt_flag & MNT_RDONLY))) { 482 error = EROFS; 483 goto bad2; 484 } 485 } 486 if (cnp->cn_flags & SAVESTART) { 487 ndp->ni_startdir = ndp->ni_dvp; 488 VREF(ndp->ni_startdir); 489 } 490 if (!wantparent) 491 vrele(ndp->ni_dvp); 492 if ((cnp->cn_flags & LOCKLEAF) == 0) 493 VOP_UNLOCK(dp); 494 return (0); 495 496 bad2: 497 if ((cnp->cn_flags & LOCKPARENT) && *ndp->ni_next == '\0') 498 VOP_UNLOCK(ndp->ni_dvp); 499 vrele(ndp->ni_dvp); 500 bad: 501 vput(dp); 502 ndp->ni_vp = NULL; 503 return (error); 504 } 505 506 507