vfs_lookup.c revision 191991
1139804Simp/*- 21541Srgrimes * Copyright (c) 1982, 1986, 1989, 1993 31541Srgrimes * The Regents of the University of California. All rights reserved. 41541Srgrimes * (c) UNIX System Laboratories, Inc. 51541Srgrimes * All or some portions of this file are derived from material licensed 61541Srgrimes * to the University of California by American Telephone and Telegraph 71541Srgrimes * Co. or Unix System Laboratories, Inc. and are reproduced herein with 81541Srgrimes * the permission of UNIX System Laboratories, Inc. 91541Srgrimes * 101541Srgrimes * Redistribution and use in source and binary forms, with or without 111541Srgrimes * modification, are permitted provided that the following conditions 121541Srgrimes * are met: 131541Srgrimes * 1. Redistributions of source code must retain the above copyright 141541Srgrimes * notice, this list of conditions and the following disclaimer. 151541Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 161541Srgrimes * notice, this list of conditions and the following disclaimer in the 171541Srgrimes * documentation and/or other materials provided with the distribution. 181541Srgrimes * 4. Neither the name of the University nor the names of its contributors 191541Srgrimes * may be used to endorse or promote products derived from this software 201541Srgrimes * without specific prior written permission. 211541Srgrimes * 221541Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 231541Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 241541Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 251541Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 261541Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 271541Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 281541Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 291541Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 301541Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 311541Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 321541Srgrimes * SUCH DAMAGE. 331541Srgrimes * 341541Srgrimes * @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94 351541Srgrimes */ 361541Srgrimes 37116182Sobrien#include <sys/cdefs.h> 38116182Sobrien__FBSDID("$FreeBSD: head/sys/kern/vfs_lookup.c 191991 2009-05-11 16:32:58Z attilio $"); 39116182Sobrien 40190759Srwatson#include "opt_kdtrace.h" 4113203Swollman#include "opt_ktrace.h" 42101127Srwatson#include "opt_mac.h" 4313203Swollman 441541Srgrimes#include <sys/param.h> 452112Swollman#include <sys/systm.h> 4669664Speter#include <sys/kernel.h> 47177785Skib#include <sys/fcntl.h> 4876166Smarkm#include <sys/lock.h> 4989316Salfred#include <sys/mutex.h> 501541Srgrimes#include <sys/namei.h> 511541Srgrimes#include <sys/vnode.h> 521541Srgrimes#include <sys/mount.h> 531541Srgrimes#include <sys/filedesc.h> 541541Srgrimes#include <sys/proc.h> 55190759Srwatson#include <sys/sdt.h> 56141471Sjhb#include <sys/syscallsubr.h> 57144613Sjeff#include <sys/sysctl.h> 581541Srgrimes#ifdef KTRACE 591541Srgrimes#include <sys/ktrace.h> 601541Srgrimes#endif 611541Srgrimes 62155334Srwatson#include <security/audit/audit.h> 63163606Srwatson#include <security/mac/mac_framework.h> 64155334Srwatson 6592751Sjeff#include <vm/uma.h> 6632011Sbde 67155168Sjeff#define NAMEI_DIAGNOSTIC 1 68138345Sphk#undef NAMEI_DIAGNOSTIC 69138345Sphk 70190759SrwatsonSDT_PROVIDER_DECLARE(vfs); 71190759SrwatsonSDT_PROBE_DEFINE3(vfs, namei, lookup, entry, "struct vnode *", "char *", 72190759Srwatson "unsigned long"); 73190759SrwatsonSDT_PROBE_DEFINE2(vfs, namei, lookup, return, "int", "struct vnode *"); 74190759Srwatson 751541Srgrimes/* 7669664Speter * Allocation zone for namei 7769664Speter */ 7892751Sjeffuma_zone_t namei_zone; 79166167Skib/* 80166167Skib * Placeholder vnode for mp traversal 81166167Skib */ 82166167Skibstatic struct vnode *vp_crossmp; 8369664Speter 8469664Speterstatic void 8569664Speternameiinit(void *dummy __unused) 8669664Speter{ 87168138Srwatson int error; 88168138Srwatson 8992654Sjeff namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, 9092654Sjeff UMA_ALIGN_PTR, 0); 91168138Srwatson error = getnewvnode("crossmp", NULL, &dead_vnodeops, &vp_crossmp); 92168138Srwatson if (error != 0) 93168138Srwatson panic("nameiinit: getnewvnode"); 94176519Sattilio VN_LOCK_ASHARE(vp_crossmp); 9569664Speter} 96177253SrwatsonSYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); 9769664Speter 98183520Sjhbstatic int lookup_shared = 1; 99144613SjeffSYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &lookup_shared, 0, 100144613Sjeff "Enables/Disables shared locks for path name translation"); 101183519SjhbTUNABLE_INT("vfs.lookup_shared", &lookup_shared); 102144613Sjeff 10369664Speter/* 104161010Srwatson * Convert a pathname into a pointer to a locked vnode. 1051541Srgrimes * 1061541Srgrimes * The FOLLOW flag is set when symbolic links are to be followed 1071541Srgrimes * when they occur at the end of the name translation process. 1081541Srgrimes * Symbolic links are always followed for all other pathname 1091541Srgrimes * components other than the last. 1101541Srgrimes * 1111541Srgrimes * The segflg defines whether the name is to be copied from user 1121541Srgrimes * space or kernel space. 1131541Srgrimes * 1141541Srgrimes * Overall outline of namei: 1151541Srgrimes * 1161541Srgrimes * copy in name 1171541Srgrimes * get starting directory 1181541Srgrimes * while (!done && !error) { 1191541Srgrimes * call lookup to search path. 1201541Srgrimes * if symbolic link, massage name in buffer and continue 1211541Srgrimes * } 1221541Srgrimes */ 1231541Srgrimesint 124161011Srwatsonnamei(struct nameidata *ndp) 1251541Srgrimes{ 126161011Srwatson struct filedesc *fdp; /* pointer to file descriptor state */ 127161011Srwatson char *cp; /* pointer into pathname argument */ 128161011Srwatson struct vnode *dp; /* the directory we are searching */ 1291541Srgrimes struct iovec aiov; /* uio for reading symbolic links */ 1301541Srgrimes struct uio auio; 1311541Srgrimes int error, linklen; 1321541Srgrimes struct componentname *cnp = &ndp->ni_cnd; 13383366Sjulian struct thread *td = cnp->cn_thread; 13483366Sjulian struct proc *p = td->td_proc; 135140714Sjeff int vfslocked; 1361541Srgrimes 137150164Scsjp KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0, 138150164Scsjp ("NOT MPSAFE and Giant not held")); 13991419Sjhb ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; 14083366Sjulian KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc")); 14142408Seivind KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, 14242453Seivind ("namei: nameiop contaminated with flags")); 14342408Seivind KASSERT((cnp->cn_flags & OPMASK) == 0, 14442453Seivind ("namei: flags contaminated with nameiops")); 145144613Sjeff if (!lookup_shared) 146144613Sjeff cnp->cn_flags &= ~LOCKSHARED; 14783366Sjulian fdp = p->p_fd; 1481541Srgrimes 1491541Srgrimes /* 1501541Srgrimes * Get a buffer for the name to be translated, and copy the 1511541Srgrimes * name into the buffer. 1521541Srgrimes */ 1531541Srgrimes if ((cnp->cn_flags & HASBUF) == 0) 154111119Simp cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK); 1551541Srgrimes if (ndp->ni_segflg == UIO_SYSSPACE) 1561541Srgrimes error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, 15736735Sdfr MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 1581541Srgrimes else 1591541Srgrimes error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, 16036735Sdfr MAXPATHLEN, (size_t *)&ndp->ni_pathlen); 16120069Sbde 162155334Srwatson /* If we are auditing the kernel pathname, save the user pathname. */ 163155334Srwatson if (cnp->cn_flags & AUDITVNODE1) 164155334Srwatson AUDIT_ARG(upath, td, cnp->cn_pnbuf, ARG_UPATH1); 165155334Srwatson if (cnp->cn_flags & AUDITVNODE2) 166155334Srwatson AUDIT_ARG(upath, td, cnp->cn_pnbuf, ARG_UPATH2); 167155334Srwatson 16820069Sbde /* 16920069Sbde * Don't allow empty pathnames. 17020069Sbde */ 17120069Sbde if (!error && *cnp->cn_pnbuf == '\0') 17220069Sbde error = ENOENT; 17320069Sbde 1741541Srgrimes if (error) { 17592751Sjeff uma_zfree(namei_zone, cnp->cn_pnbuf); 176100613Srwatson#ifdef DIAGNOSTIC 177100613Srwatson cnp->cn_pnbuf = NULL; 178100613Srwatson cnp->cn_nameptr = NULL; 179100613Srwatson#endif 1801541Srgrimes ndp->ni_vp = NULL; 1811541Srgrimes return (error); 1821541Srgrimes } 1831541Srgrimes ndp->ni_loopcnt = 0; 1841541Srgrimes#ifdef KTRACE 18597994Sjhb if (KTRPOINT(td, KTR_NAMEI)) { 18697994Sjhb KASSERT(cnp->cn_thread == curthread, 18797994Sjhb ("namei not using curthread")); 18897994Sjhb ktrnamei(cnp->cn_pnbuf); 18997994Sjhb } 1901541Srgrimes#endif 1911541Srgrimes /* 1921541Srgrimes * Get starting point for the translation. 1931541Srgrimes */ 194168355Srwatson FILEDESC_SLOCK(fdp); 19533360Sdyson ndp->ni_rootdir = fdp->fd_rdir; 19651649Sphk ndp->ni_topdir = fdp->fd_jdir; 19733360Sdyson 198185029Spjd dp = NULL; 199185029Spjd if (cnp->cn_pnbuf[0] != '/') { 200185029Spjd if (ndp->ni_startdir != NULL) { 201185029Spjd dp = ndp->ni_startdir; 202185029Spjd error = 0; 203185029Spjd } else if (ndp->ni_dirfd != AT_FDCWD) 204185029Spjd error = fgetvp(td, ndp->ni_dirfd, &dp); 205185029Spjd if (error != 0 || dp != NULL) { 206185029Spjd FILEDESC_SUNLOCK(fdp); 207185029Spjd if (error == 0 && dp->v_type != VDIR) { 208185029Spjd vfslocked = VFS_LOCK_GIANT(dp->v_mount); 209185029Spjd vrele(dp); 210185029Spjd VFS_UNLOCK_GIANT(vfslocked); 211185029Spjd error = ENOTDIR; 212185029Spjd } 213177785Skib } 214177785Skib if (error) { 215177785Skib uma_zfree(namei_zone, cnp->cn_pnbuf); 216177785Skib#ifdef DIAGNOSTIC 217177785Skib cnp->cn_pnbuf = NULL; 218177785Skib cnp->cn_nameptr = NULL; 219177785Skib#endif 220177785Skib return (error); 221177785Skib } 222185029Spjd } 223185029Spjd if (dp == NULL) { 224177785Skib dp = fdp->fd_cdir; 225177785Skib VREF(dp); 226177785Skib FILEDESC_SUNLOCK(fdp); 227185029Spjd if (ndp->ni_startdir != NULL) { 228185029Spjd vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount); 229185029Spjd vrele(ndp->ni_startdir); 230185029Spjd VFS_UNLOCK_GIANT(vfslocked); 231185029Spjd } 232177785Skib } 233190759Srwatson SDT_PROBE(vfs, namei, lookup, entry, dp, cnp->cn_pnbuf, 234190759Srwatson cnp->cn_flags, 0, 0); 235140714Sjeff vfslocked = VFS_LOCK_GIANT(dp->v_mount); 2361541Srgrimes for (;;) { 2371541Srgrimes /* 2381541Srgrimes * Check if root directory should replace current directory. 2391541Srgrimes * Done at start of translation and after symbolic link. 2401541Srgrimes */ 2411541Srgrimes cnp->cn_nameptr = cnp->cn_pnbuf; 2421541Srgrimes if (*(cnp->cn_nameptr) == '/') { 2431541Srgrimes vrele(dp); 244140714Sjeff VFS_UNLOCK_GIANT(vfslocked); 2451541Srgrimes while (*(cnp->cn_nameptr) == '/') { 2461541Srgrimes cnp->cn_nameptr++; 2471541Srgrimes ndp->ni_pathlen--; 2481541Srgrimes } 2491541Srgrimes dp = ndp->ni_rootdir; 250140714Sjeff vfslocked = VFS_LOCK_GIANT(dp->v_mount); 2511541Srgrimes VREF(dp); 2521541Srgrimes } 253140714Sjeff if (vfslocked) 254140714Sjeff ndp->ni_cnd.cn_flags |= GIANTHELD; 2551541Srgrimes ndp->ni_startdir = dp; 2563148Sphk error = lookup(ndp); 2573148Sphk if (error) { 25892751Sjeff uma_zfree(namei_zone, cnp->cn_pnbuf); 259100613Srwatson#ifdef DIAGNOSTIC 260100613Srwatson cnp->cn_pnbuf = NULL; 261100613Srwatson cnp->cn_nameptr = NULL; 262100613Srwatson#endif 263190759Srwatson SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 264190759Srwatson 0, 0); 2651541Srgrimes return (error); 2661541Srgrimes } 267140714Sjeff vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 268140714Sjeff ndp->ni_cnd.cn_flags &= ~GIANTHELD; 2691541Srgrimes /* 2701541Srgrimes * Check for symbolic link 2711541Srgrimes */ 2721541Srgrimes if ((cnp->cn_flags & ISSYMLINK) == 0) { 273100613Srwatson if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { 27492751Sjeff uma_zfree(namei_zone, cnp->cn_pnbuf); 275100613Srwatson#ifdef DIAGNOSTIC 276100613Srwatson cnp->cn_pnbuf = NULL; 277100613Srwatson cnp->cn_nameptr = NULL; 278100613Srwatson#endif 279100613Srwatson } else 2801541Srgrimes cnp->cn_flags |= HASBUF; 28132286Sdyson 282140714Sjeff if ((cnp->cn_flags & MPSAFE) == 0) { 283140714Sjeff VFS_UNLOCK_GIANT(vfslocked); 284140714Sjeff } else if (vfslocked) 285140714Sjeff ndp->ni_cnd.cn_flags |= GIANTHELD; 286190759Srwatson SDT_PROBE(vfs, namei, lookup, return, 0, ndp->ni_vp, 287190759Srwatson 0, 0, 0); 2881541Srgrimes return (0); 2891541Srgrimes } 2901541Srgrimes if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { 2911541Srgrimes error = ELOOP; 2921541Srgrimes break; 2931541Srgrimes } 294101127Srwatson#ifdef MAC 295105479Srwatson if ((cnp->cn_flags & NOMACCHECK) == 0) { 296172930Srwatson error = mac_vnode_check_readlink(td->td_ucred, 297105479Srwatson ndp->ni_vp); 298105479Srwatson if (error) 299105479Srwatson break; 300105479Srwatson } 301101127Srwatson#endif 3021541Srgrimes if (ndp->ni_pathlen > 1) 303111119Simp cp = uma_zalloc(namei_zone, M_WAITOK); 3041541Srgrimes else 3051541Srgrimes cp = cnp->cn_pnbuf; 3061541Srgrimes aiov.iov_base = cp; 3071541Srgrimes aiov.iov_len = MAXPATHLEN; 3081541Srgrimes auio.uio_iov = &aiov; 3091541Srgrimes auio.uio_iovcnt = 1; 3101541Srgrimes auio.uio_offset = 0; 3111541Srgrimes auio.uio_rw = UIO_READ; 3121541Srgrimes auio.uio_segflg = UIO_SYSSPACE; 31383366Sjulian auio.uio_td = (struct thread *)0; 3141541Srgrimes auio.uio_resid = MAXPATHLEN; 3153148Sphk error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); 3163148Sphk if (error) { 3171541Srgrimes if (ndp->ni_pathlen > 1) 31892751Sjeff uma_zfree(namei_zone, cp); 3191541Srgrimes break; 3201541Srgrimes } 3211541Srgrimes linklen = MAXPATHLEN - auio.uio_resid; 32278692Sdillon if (linklen == 0) { 32378692Sdillon if (ndp->ni_pathlen > 1) 32492751Sjeff uma_zfree(namei_zone, cp); 32578692Sdillon error = ENOENT; 32678692Sdillon break; 32778692Sdillon } 3281541Srgrimes if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { 3291541Srgrimes if (ndp->ni_pathlen > 1) 33092751Sjeff uma_zfree(namei_zone, cp); 3311541Srgrimes error = ENAMETOOLONG; 3321541Srgrimes break; 3331541Srgrimes } 3341541Srgrimes if (ndp->ni_pathlen > 1) { 3351541Srgrimes bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); 33692751Sjeff uma_zfree(namei_zone, cnp->cn_pnbuf); 3371541Srgrimes cnp->cn_pnbuf = cp; 3381541Srgrimes } else 3391541Srgrimes cnp->cn_pnbuf[linklen] = '\0'; 3401541Srgrimes ndp->ni_pathlen += linklen; 3411541Srgrimes vput(ndp->ni_vp); 3421541Srgrimes dp = ndp->ni_dvp; 3431541Srgrimes } 34492751Sjeff uma_zfree(namei_zone, cnp->cn_pnbuf); 345100613Srwatson#ifdef DIAGNOSTIC 346100613Srwatson cnp->cn_pnbuf = NULL; 347100613Srwatson cnp->cn_nameptr = NULL; 348100613Srwatson#endif 349144833Sjeff vput(ndp->ni_vp); 350144833Sjeff ndp->ni_vp = NULL; 3511541Srgrimes vrele(ndp->ni_dvp); 352140714Sjeff VFS_UNLOCK_GIANT(vfslocked); 353190759Srwatson SDT_PROBE(vfs, namei, lookup, return, error, NULL, 0, 0, 0); 3541541Srgrimes return (error); 3551541Srgrimes} 3561541Srgrimes 357162288Smohansstatic int 358162288Smohanscompute_cn_lkflags(struct mount *mp, int lkflags) 359162288Smohans{ 360184597Sjhb 361162310Smohans if (mp == NULL || 362162310Smohans ((lkflags & LK_SHARED) && !(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED))) { 363162288Smohans lkflags &= ~LK_SHARED; 364162288Smohans lkflags |= LK_EXCLUSIVE; 365162288Smohans } 366184597Sjhb return (lkflags); 367162288Smohans} 368162288Smohans 369189696Sjhbstatic __inline int 370189696Sjhbneeds_exclusive_leaf(struct mount *mp, int flags) 371189696Sjhb{ 372189696Sjhb 373189696Sjhb /* 374189696Sjhb * Intermediate nodes can use shared locks, we only need to 375189696Sjhb * force an exclusive lock for leaf nodes. 376189696Sjhb */ 377189696Sjhb if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) 378189696Sjhb return (0); 379189696Sjhb 380189696Sjhb /* Always use exclusive locks if LOCKSHARED isn't set. */ 381189696Sjhb if (!(flags & LOCKSHARED)) 382189696Sjhb return (1); 383189696Sjhb 384189696Sjhb /* 385189696Sjhb * For lookups during open(), if the mount point supports 386189696Sjhb * extended shared operations, then use a shared lock for the 387189696Sjhb * leaf node, otherwise use an exclusive lock. 388189696Sjhb */ 389189696Sjhb if (flags & ISOPEN) { 390189696Sjhb if (mp != NULL && 391189696Sjhb (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED)) 392189696Sjhb return (0); 393189696Sjhb else 394189696Sjhb return (1); 395189696Sjhb } 396189696Sjhb 397189696Sjhb /* 398189696Sjhb * Lookup requests outside of open() that specify LOCKSHARED 399189696Sjhb * only need a shared lock on the leaf vnode. 400189696Sjhb */ 401189697Sjhb return (0); 402189696Sjhb} 403189696Sjhb 4041541Srgrimes/* 4051541Srgrimes * Search a pathname. 4061541Srgrimes * This is a very central and rather complicated routine. 4071541Srgrimes * 4081541Srgrimes * The pathname is pointed to by ni_ptr and is of length ni_pathlen. 4091541Srgrimes * The starting directory is taken from ni_startdir. The pathname is 4101541Srgrimes * descended until done, or a symbolic link is encountered. The variable 4111541Srgrimes * ni_more is clear if the path is completed; it is set to one if a 4121541Srgrimes * symbolic link needing interpretation is encountered. 4131541Srgrimes * 4141541Srgrimes * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on 4151541Srgrimes * whether the name is to be looked up, created, renamed, or deleted. 4161541Srgrimes * When CREATE, RENAME, or DELETE is specified, information usable in 4171541Srgrimes * creating, renaming, or deleting a directory entry may be calculated. 4181541Srgrimes * If flag has LOCKPARENT or'ed into it, the parent directory is returned 4191541Srgrimes * locked. If flag has WANTPARENT or'ed into it, the parent directory is 4201541Srgrimes * returned unlocked. Otherwise the parent directory is not returned. If 4211541Srgrimes * the target of the pathname exists and LOCKLEAF is or'ed into the flag 4221541Srgrimes * the target is returned locked, otherwise it is returned unlocked. 4231541Srgrimes * When creating or renaming and LOCKPARENT is specified, the target may not 4241541Srgrimes * be ".". When deleting and LOCKPARENT is specified, the target may be ".". 4258876Srgrimes * 4261541Srgrimes * Overall outline of lookup: 4271541Srgrimes * 4281541Srgrimes * dirloop: 4291541Srgrimes * identify next component of name at ndp->ni_ptr 4301541Srgrimes * handle degenerate case where name is null string 4311541Srgrimes * if .. and crossing mount points and on mounted filesys, find parent 4321541Srgrimes * call VOP_LOOKUP routine for next component name 4331541Srgrimes * directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set 4341541Srgrimes * component vnode returned in ni_vp (if it exists), locked. 4351541Srgrimes * if result vnode is mounted on and crossing mount points, 4361541Srgrimes * find mounted on vnode 4371541Srgrimes * if more components of name, do next level at dirloop 4381541Srgrimes * return the answer in ni_vp, locked if LOCKLEAF set 4391541Srgrimes * if LOCKPARENT set, return locked parent in ni_dvp 4401541Srgrimes * if WANTPARENT set, return unlocked parent in ni_dvp 4411541Srgrimes */ 4421541Srgrimesint 443161011Srwatsonlookup(struct nameidata *ndp) 4441541Srgrimes{ 445161011Srwatson char *cp; /* pointer into pathname argument */ 446161011Srwatson struct vnode *dp = 0; /* the directory we are searching */ 4471541Srgrimes struct vnode *tdp; /* saved dp */ 4481541Srgrimes struct mount *mp; /* mount table entry */ 4491541Srgrimes int docache; /* == 0 do not cache last component */ 4501541Srgrimes int wantparent; /* 1 => wantparent or lockparent flag */ 4511541Srgrimes int rdonly; /* lookup read-only flag bit */ 4529804Sbde int trailing_slash; 4531541Srgrimes int error = 0; 45465805Sbp int dpunlocked = 0; /* dp has already been unlocked */ 4551541Srgrimes struct componentname *cnp = &ndp->ni_cnd; 456158094Sjeff int vfslocked; /* VFS Giant state for child */ 457158094Sjeff int dvfslocked; /* VFS Giant state for parent */ 458140714Sjeff int tvfslocked; 459162288Smohans int lkflags_save; 460191991Sattilio#ifdef AUDIT 461191991Sattilio struct thread *td = curthread; 462191991Sattilio#endif 463162288Smohans 4641541Srgrimes /* 4651541Srgrimes * Setup: break out flag bits into variables. 4661541Srgrimes */ 467158094Sjeff dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; 468158094Sjeff vfslocked = 0; 469140714Sjeff ndp->ni_cnd.cn_flags &= ~GIANTHELD; 4701541Srgrimes wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); 471144229Sjeff KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, 472144229Sjeff ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); 4731541Srgrimes docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; 4741541Srgrimes if (cnp->cn_nameiop == DELETE || 47522874Sbde (wantparent && cnp->cn_nameiop != CREATE && 47622874Sbde cnp->cn_nameiop != LOOKUP)) 4771541Srgrimes docache = 0; 4781541Srgrimes rdonly = cnp->cn_flags & RDONLY; 479144286Sjeff cnp->cn_flags &= ~ISSYMLINK; 4801541Srgrimes ndp->ni_dvp = NULL; 481144286Sjeff /* 482144286Sjeff * We use shared locks until we hit the parent of the last cn then 483144286Sjeff * we adjust based on the requesting flags. 484144286Sjeff */ 485144613Sjeff if (lookup_shared) 486144613Sjeff cnp->cn_lkflags = LK_SHARED; 487144613Sjeff else 488144613Sjeff cnp->cn_lkflags = LK_EXCLUSIVE; 4891541Srgrimes dp = ndp->ni_startdir; 4901541Srgrimes ndp->ni_startdir = NULLVP; 491175202Sattilio vn_lock(dp, 492175202Sattilio compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); 4931541Srgrimes 4941541Srgrimesdirloop: 4951541Srgrimes /* 4961541Srgrimes * Search a new directory. 4971541Srgrimes * 4981541Srgrimes * The last component of the filename is left accessible via 4991541Srgrimes * cnp->cn_nameptr for callers that need the name. Callers needing 5001541Srgrimes * the name set the SAVENAME flag. When done, they assume 5011541Srgrimes * responsibility for freeing the pathname buffer. 5021541Srgrimes */ 5031541Srgrimes cnp->cn_consume = 0; 5041541Srgrimes for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) 50551906Sphk continue; 5061541Srgrimes cnp->cn_namelen = cp - cnp->cn_nameptr; 5071541Srgrimes if (cnp->cn_namelen > NAME_MAX) { 5081541Srgrimes error = ENAMETOOLONG; 5091541Srgrimes goto bad; 5101541Srgrimes } 5111541Srgrimes#ifdef NAMEI_DIAGNOSTIC 5121541Srgrimes { char c = *cp; 5131541Srgrimes *cp = '\0'; 5141541Srgrimes printf("{%s}: ", cnp->cn_nameptr); 5151541Srgrimes *cp = c; } 5161541Srgrimes#endif 5171541Srgrimes ndp->ni_pathlen -= cnp->cn_namelen; 5181541Srgrimes ndp->ni_next = cp; 5199804Sbde 5209804Sbde /* 5219804Sbde * Replace multiple slashes by a single slash and trailing slashes 5229804Sbde * by a null. This must be done before VOP_LOOKUP() because some 5239804Sbde * fs's don't know about trailing slashes. Remember if there were 5249804Sbde * trailing slashes to handle symlinks, existing non-directories 5259804Sbde * and non-existing files that won't be directories specially later. 5269804Sbde */ 5279804Sbde trailing_slash = 0; 5289804Sbde while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { 5299804Sbde cp++; 5309804Sbde ndp->ni_pathlen--; 5319804Sbde if (*cp == '\0') { 5329804Sbde trailing_slash = 1; 5339804Sbde *ndp->ni_next = '\0'; /* XXX for direnter() ... */ 5349804Sbde } 5359804Sbde } 5369804Sbde ndp->ni_next = cp; 5379804Sbde 5381541Srgrimes cnp->cn_flags |= MAKEENTRY; 5391541Srgrimes if (*cp == '\0' && docache == 0) 5401541Srgrimes cnp->cn_flags &= ~MAKEENTRY; 5411541Srgrimes if (cnp->cn_namelen == 2 && 5421541Srgrimes cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') 5431541Srgrimes cnp->cn_flags |= ISDOTDOT; 5441541Srgrimes else 5451541Srgrimes cnp->cn_flags &= ~ISDOTDOT; 5461541Srgrimes if (*ndp->ni_next == 0) 5471541Srgrimes cnp->cn_flags |= ISLASTCN; 5481541Srgrimes else 5491541Srgrimes cnp->cn_flags &= ~ISLASTCN; 5501541Srgrimes 5511541Srgrimes 5521541Srgrimes /* 5531541Srgrimes * Check for degenerate name (e.g. / or "") 5541541Srgrimes * which is a way of talking about a directory, 5551541Srgrimes * e.g. like "/." or ".". 5561541Srgrimes */ 5571541Srgrimes if (cnp->cn_nameptr[0] == '\0') { 55822521Sdyson if (dp->v_type != VDIR) { 55922521Sdyson error = ENOTDIR; 56022521Sdyson goto bad; 56122521Sdyson } 5621541Srgrimes if (cnp->cn_nameiop != LOOKUP) { 5631541Srgrimes error = EISDIR; 5641541Srgrimes goto bad; 5651541Srgrimes } 5661541Srgrimes if (wantparent) { 5671541Srgrimes ndp->ni_dvp = dp; 5681541Srgrimes VREF(dp); 5691541Srgrimes } 5701541Srgrimes ndp->ni_vp = dp; 571155334Srwatson 572155334Srwatson if (cnp->cn_flags & AUDITVNODE1) 573155334Srwatson AUDIT_ARG(vnode, dp, ARG_VNODE1); 574155334Srwatson else if (cnp->cn_flags & AUDITVNODE2) 575155334Srwatson AUDIT_ARG(vnode, dp, ARG_VNODE2); 576155334Srwatson 5771541Srgrimes if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) 578175294Sattilio VOP_UNLOCK(dp, 0); 57954655Seivind /* XXX This should probably move to the top of function. */ 5801541Srgrimes if (cnp->cn_flags & SAVESTART) 5811541Srgrimes panic("lookup: SAVESTART"); 582140714Sjeff goto success; 5831541Srgrimes } 5841541Srgrimes 5851541Srgrimes /* 586154649Struckman * Handle "..": four special cases. 587154649Struckman * 1. Return an error if this is the last component of 588154649Struckman * the name and the operation is DELETE or RENAME. 589154649Struckman * 2. If at root directory (e.g. after chroot) 5901541Srgrimes * or at absolute root directory 5911541Srgrimes * then ignore it so can't get out. 592154649Struckman * 3. If this vnode is the root of a mounted 5931541Srgrimes * filesystem, then replace it with the 5941541Srgrimes * vnode which was mounted on so we take the 59596755Strhodes * .. in the other filesystem. 596154649Struckman * 4. If the vnode is the top directory of 59751649Sphk * the jail or chroot, don't let them out. 5981541Srgrimes */ 5991541Srgrimes if (cnp->cn_flags & ISDOTDOT) { 600154649Struckman if ((cnp->cn_flags & ISLASTCN) != 0 && 601154649Struckman (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 602154690Struckman error = EINVAL; 603154649Struckman goto bad; 604154649Struckman } 6051541Srgrimes for (;;) { 60651649Sphk if (dp == ndp->ni_rootdir || 60751649Sphk dp == ndp->ni_topdir || 608166744Skib dp == rootvnode || 609166744Skib ((dp->v_vflag & VV_ROOT) != 0 && 610166744Skib (cnp->cn_flags & NOCROSSMOUNT) != 0)) { 6111541Srgrimes ndp->ni_dvp = dp; 6121541Srgrimes ndp->ni_vp = dp; 613158142Skris vfslocked = VFS_LOCK_GIANT(dp->v_mount); 6141541Srgrimes VREF(dp); 6151541Srgrimes goto nextname; 6161541Srgrimes } 617166744Skib if ((dp->v_vflag & VV_ROOT) == 0) 6181541Srgrimes break; 619155385Sjeff if (dp->v_iflag & VI_DOOMED) { /* forced unmount */ 620190387Sjhb error = ENOENT; 62169405Salfred goto bad; 62269405Salfred } 6231541Srgrimes tdp = dp; 624144833Sjeff dp = dp->v_mount->mnt_vnodecovered; 625158094Sjeff tvfslocked = dvfslocked; 626158094Sjeff dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 627144833Sjeff VREF(dp); 6281541Srgrimes vput(tdp); 629140714Sjeff VFS_UNLOCK_GIANT(tvfslocked); 630175202Sattilio vn_lock(dp, 631175202Sattilio compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 632175202Sattilio LK_RETRY)); 6331541Srgrimes } 6341541Srgrimes } 6351541Srgrimes 6361541Srgrimes /* 6371541Srgrimes * We now have a segment name to search for, and a directory to search. 6381541Srgrimes */ 6391541Srgrimesunionlookup: 640101127Srwatson#ifdef MAC 641105479Srwatson if ((cnp->cn_flags & NOMACCHECK) == 0) { 642191990Sattilio error = mac_vnode_check_lookup(cnp->cn_thread->td_ucred, dp, 643191990Sattilio cnp); 644105479Srwatson if (error) 645105479Srwatson goto bad; 646105479Srwatson } 647101127Srwatson#endif 6481541Srgrimes ndp->ni_dvp = dp; 64922521Sdyson ndp->ni_vp = NULL; 65024624Sdfr ASSERT_VOP_LOCKED(dp, "lookup"); 651158094Sjeff VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked)); 652144286Sjeff /* 653144286Sjeff * If we have a shared lock we may need to upgrade the lock for the 654144286Sjeff * last operation. 655144286Sjeff */ 656166167Skib if (dp != vp_crossmp && 657176559Sattilio VOP_ISLOCKED(dp) == LK_SHARED && 658144286Sjeff (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT)) 659175202Sattilio vn_lock(dp, LK_UPGRADE|LK_RETRY); 660144286Sjeff /* 661144286Sjeff * If we're looking up the last component and we need an exclusive 662144286Sjeff * lock, adjust our lkflags. 663144286Sjeff */ 664189696Sjhb if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) 665144286Sjeff cnp->cn_lkflags = LK_EXCLUSIVE; 666138345Sphk#ifdef NAMEI_DIAGNOSTIC 667138345Sphk vprint("lookup in", dp); 668138345Sphk#endif 669162288Smohans lkflags_save = cnp->cn_lkflags; 670162288Smohans cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags); 67143301Sdillon if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { 672162288Smohans cnp->cn_lkflags = lkflags_save; 67342408Seivind KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); 6741541Srgrimes#ifdef NAMEI_DIAGNOSTIC 6751541Srgrimes printf("not found\n"); 6761541Srgrimes#endif 6771541Srgrimes if ((error == ENOENT) && 678101308Sjeff (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && 6791541Srgrimes (dp->v_mount->mnt_flag & MNT_UNION)) { 6801541Srgrimes tdp = dp; 681144833Sjeff dp = dp->v_mount->mnt_vnodecovered; 682158094Sjeff tvfslocked = dvfslocked; 683158094Sjeff dvfslocked = VFS_LOCK_GIANT(dp->v_mount); 684144833Sjeff VREF(dp); 685144203Sjeff vput(tdp); 686140714Sjeff VFS_UNLOCK_GIANT(tvfslocked); 687175202Sattilio vn_lock(dp, 688175202Sattilio compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | 689175202Sattilio LK_RETRY)); 6901541Srgrimes goto unionlookup; 6911541Srgrimes } 6921541Srgrimes 6931541Srgrimes if (error != EJUSTRETURN) 6941541Srgrimes goto bad; 6951541Srgrimes /* 6961541Srgrimes * If creating and at end of pathname, then can consider 6971541Srgrimes * allowing file to be created. 6981541Srgrimes */ 69911644Sdg if (rdonly) { 7001541Srgrimes error = EROFS; 7011541Srgrimes goto bad; 7021541Srgrimes } 7039804Sbde if (*cp == '\0' && trailing_slash && 7049804Sbde !(cnp->cn_flags & WILLBEDIR)) { 7059804Sbde error = ENOENT; 7069804Sbde goto bad; 7079804Sbde } 708144203Sjeff if ((cnp->cn_flags & LOCKPARENT) == 0) 709175294Sattilio VOP_UNLOCK(dp, 0); 7101541Srgrimes /* 711144203Sjeff * This is a temporary assert to make sure I know what the 712144203Sjeff * behavior here was. 713144203Sjeff */ 714144203Sjeff KASSERT((cnp->cn_flags & (WANTPARENT|LOCKPARENT)) != 0, 715144203Sjeff ("lookup: Unhandled case.")); 716144203Sjeff /* 7171541Srgrimes * We return with ni_vp NULL to indicate that the entry 7181541Srgrimes * doesn't currently exist, leaving a pointer to the 719161010Srwatson * (possibly locked) directory vnode in ndp->ni_dvp. 7201541Srgrimes */ 7211541Srgrimes if (cnp->cn_flags & SAVESTART) { 7221541Srgrimes ndp->ni_startdir = ndp->ni_dvp; 7231541Srgrimes VREF(ndp->ni_startdir); 7241541Srgrimes } 725140714Sjeff goto success; 726162288Smohans } else 727162288Smohans cnp->cn_lkflags = lkflags_save; 7281541Srgrimes#ifdef NAMEI_DIAGNOSTIC 7291541Srgrimes printf("found\n"); 7301541Srgrimes#endif 731144203Sjeff /* 7321541Srgrimes * Take into account any additional components consumed by 7331541Srgrimes * the underlying filesystem. 7341541Srgrimes */ 7351541Srgrimes if (cnp->cn_consume > 0) { 7361541Srgrimes cnp->cn_nameptr += cnp->cn_consume; 7371541Srgrimes ndp->ni_next += cnp->cn_consume; 7381541Srgrimes ndp->ni_pathlen -= cnp->cn_consume; 7391541Srgrimes cnp->cn_consume = 0; 7401541Srgrimes } 7411541Srgrimes 7421541Srgrimes dp = ndp->ni_vp; 743158094Sjeff vfslocked = VFS_LOCK_GIANT(dp->v_mount); 7441541Srgrimes 7451541Srgrimes /* 7461541Srgrimes * Check to see if the vnode has been mounted on; 74796755Strhodes * if so find the root of the mounted filesystem. 7481541Srgrimes */ 7491541Srgrimes while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && 7501541Srgrimes (cnp->cn_flags & NOCROSSMOUNT) == 0) { 751184554Sattilio if (vfs_busy(mp, 0)) 7521541Srgrimes continue; 753144833Sjeff vput(dp); 754158094Sjeff VFS_UNLOCK_GIANT(vfslocked); 755155168Sjeff vfslocked = VFS_LOCK_GIANT(mp); 756158094Sjeff if (dp != ndp->ni_dvp) 757166167Skib vput(ndp->ni_dvp); 758166167Skib else 759166167Skib vrele(ndp->ni_dvp); 760166167Skib VFS_UNLOCK_GIANT(dvfslocked); 761166167Skib dvfslocked = 0; 762166167Skib vref(vp_crossmp); 763166167Skib ndp->ni_dvp = vp_crossmp; 764191990Sattilio error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags), 765191990Sattilio &tdp); 766182542Sattilio vfs_unbusy(mp); 767175202Sattilio if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) 768166167Skib panic("vp_crossmp exclusively locked or reclaimed"); 76965805Sbp if (error) { 77065805Sbp dpunlocked = 1; 7711541Srgrimes goto bad2; 77265805Sbp } 7731541Srgrimes ndp->ni_vp = dp = tdp; 7741541Srgrimes } 7751541Srgrimes 77610219Sdfr /* 77710219Sdfr * Check for symbolic link 77810219Sdfr */ 77910219Sdfr if ((dp->v_type == VLNK) && 78010219Sdfr ((cnp->cn_flags & FOLLOW) || trailing_slash || 78110219Sdfr *ndp->ni_next == '/')) { 78210219Sdfr cnp->cn_flags |= ISSYMLINK; 783155385Sjeff if (dp->v_iflag & VI_DOOMED) { 784190387Sjhb /* 785190387Sjhb * We can't know whether the directory was mounted with 786190387Sjhb * NOSYMFOLLOW, so we can't follow safely. 787190387Sjhb */ 788190387Sjhb error = ENOENT; 78969405Salfred goto bad2; 79069405Salfred } 79135105Swosch if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { 79235105Swosch error = EACCES; 79335105Swosch goto bad2; 79435105Swosch } 795144833Sjeff /* 796144833Sjeff * Symlink code always expects an unlocked dvp. 797144833Sjeff */ 798144833Sjeff if (ndp->ni_dvp != ndp->ni_vp) 799175294Sattilio VOP_UNLOCK(ndp->ni_dvp, 0); 800140714Sjeff goto success; 80110219Sdfr } 80210219Sdfr 80310219Sdfr /* 80410219Sdfr * Check for bogus trailing slashes. 80510219Sdfr */ 80610219Sdfr if (trailing_slash && dp->v_type != VDIR) { 80710219Sdfr error = ENOTDIR; 80810219Sdfr goto bad2; 80910219Sdfr } 81010219Sdfr 8111541Srgrimesnextname: 8121541Srgrimes /* 8131541Srgrimes * Not a symbolic link. If more pathname, 8141541Srgrimes * continue at next component, else return. 8151541Srgrimes */ 816144203Sjeff KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', 817144203Sjeff ("lookup: invalid path state.")); 8181541Srgrimes if (*ndp->ni_next == '/') { 8191541Srgrimes cnp->cn_nameptr = ndp->ni_next; 8201541Srgrimes while (*cnp->cn_nameptr == '/') { 8211541Srgrimes cnp->cn_nameptr++; 8221541Srgrimes ndp->ni_pathlen--; 8231541Srgrimes } 824144833Sjeff if (ndp->ni_dvp != dp) 825144833Sjeff vput(ndp->ni_dvp); 826144833Sjeff else 827144833Sjeff vrele(ndp->ni_dvp); 828155168Sjeff VFS_UNLOCK_GIANT(dvfslocked); 829158094Sjeff dvfslocked = vfslocked; /* dp becomes dvp in dirloop */ 830158094Sjeff vfslocked = 0; 8311541Srgrimes goto dirloop; 8321541Srgrimes } 8331541Srgrimes /* 83496755Strhodes * Disallow directory write attempts on read-only filesystems. 8351541Srgrimes */ 83611644Sdg if (rdonly && 83711644Sdg (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 83811644Sdg error = EROFS; 83911644Sdg goto bad2; 8401541Srgrimes } 8411541Srgrimes if (cnp->cn_flags & SAVESTART) { 8421541Srgrimes ndp->ni_startdir = ndp->ni_dvp; 8431541Srgrimes VREF(ndp->ni_startdir); 8441541Srgrimes } 845144833Sjeff if (!wantparent) { 846144833Sjeff if (ndp->ni_dvp != dp) 847144833Sjeff vput(ndp->ni_dvp); 848144833Sjeff else 849144833Sjeff vrele(ndp->ni_dvp); 850155168Sjeff VFS_UNLOCK_GIANT(dvfslocked); 851155168Sjeff dvfslocked = 0; 852144833Sjeff } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) 853175294Sattilio VOP_UNLOCK(ndp->ni_dvp, 0); 85432071Sdyson 855155334Srwatson if (cnp->cn_flags & AUDITVNODE1) 856155334Srwatson AUDIT_ARG(vnode, dp, ARG_VNODE1); 857155334Srwatson else if (cnp->cn_flags & AUDITVNODE2) 858155334Srwatson AUDIT_ARG(vnode, dp, ARG_VNODE2); 859155334Srwatson 8601541Srgrimes if ((cnp->cn_flags & LOCKLEAF) == 0) 861175294Sattilio VOP_UNLOCK(dp, 0); 862140714Sjeffsuccess: 863172274Spjd /* 864172274Spjd * Because of lookup_shared we may have the vnode shared locked, but 865172274Spjd * the caller may want it to be exclusively locked. 866172274Spjd */ 867189696Sjhb if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && 868189696Sjhb VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { 869175202Sattilio vn_lock(dp, LK_UPGRADE | LK_RETRY); 870186276Skib if (dp->v_iflag & VI_DOOMED) { 871186276Skib error = ENOENT; 872186276Skib goto bad2; 873186276Skib } 874172274Spjd } 875155168Sjeff if (vfslocked && dvfslocked) 876155168Sjeff VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */ 877155168Sjeff if (vfslocked || dvfslocked) 878140714Sjeff ndp->ni_cnd.cn_flags |= GIANTHELD; 8791541Srgrimes return (0); 8801541Srgrimes 8811541Srgrimesbad2: 882144833Sjeff if (dp != ndp->ni_dvp) 883144203Sjeff vput(ndp->ni_dvp); 884144203Sjeff else 885144203Sjeff vrele(ndp->ni_dvp); 8861541Srgrimesbad: 887144833Sjeff if (!dpunlocked) 88865805Sbp vput(dp); 889140714Sjeff VFS_UNLOCK_GIANT(vfslocked); 890155168Sjeff VFS_UNLOCK_GIANT(dvfslocked); 891140714Sjeff ndp->ni_cnd.cn_flags &= ~GIANTHELD; 8921541Srgrimes ndp->ni_vp = NULL; 8931541Srgrimes return (error); 8941541Srgrimes} 8951541Srgrimes 8963148Sphk/* 8973148Sphk * relookup - lookup a path name component 898170035Srwatson * Used by lookup to re-acquire things. 8993148Sphk */ 9003148Sphkint 901161011Srwatsonrelookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) 9023148Sphk{ 90322521Sdyson struct vnode *dp = 0; /* the directory we are searching */ 9043148Sphk int wantparent; /* 1 => wantparent or lockparent flag */ 9053148Sphk int rdonly; /* lookup read-only flag bit */ 9063148Sphk int error = 0; 9071541Srgrimes 908144203Sjeff KASSERT(cnp->cn_flags & ISLASTCN, 909144203Sjeff ("relookup: Not given last component.")); 9103148Sphk /* 9113148Sphk * Setup: break out flag bits into variables. 9123148Sphk */ 9133148Sphk wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); 914145004Sjeff KASSERT(wantparent, ("relookup: parent not wanted.")); 9153148Sphk rdonly = cnp->cn_flags & RDONLY; 9163148Sphk cnp->cn_flags &= ~ISSYMLINK; 9173148Sphk dp = dvp; 918144286Sjeff cnp->cn_lkflags = LK_EXCLUSIVE; 919175202Sattilio vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); 9203148Sphk 9213148Sphk /* 9223148Sphk * Search a new directory. 9233148Sphk * 9243148Sphk * The last component of the filename is left accessible via 9253148Sphk * cnp->cn_nameptr for callers that need the name. Callers needing 9263148Sphk * the name set the SAVENAME flag. When done, they assume 9273148Sphk * responsibility for freeing the pathname buffer. 9283148Sphk */ 9293148Sphk#ifdef NAMEI_DIAGNOSTIC 9303148Sphk printf("{%s}: ", cnp->cn_nameptr); 9313148Sphk#endif 9323148Sphk 9333148Sphk /* 9343148Sphk * Check for degenerate name (e.g. / or "") 9353148Sphk * which is a way of talking about a directory, 9363148Sphk * e.g. like "/." or ".". 9373148Sphk */ 9383148Sphk if (cnp->cn_nameptr[0] == '\0') { 9393148Sphk if (cnp->cn_nameiop != LOOKUP || wantparent) { 9403148Sphk error = EISDIR; 9413148Sphk goto bad; 9423148Sphk } 9433148Sphk if (dp->v_type != VDIR) { 9443148Sphk error = ENOTDIR; 9453148Sphk goto bad; 9463148Sphk } 9473148Sphk if (!(cnp->cn_flags & LOCKLEAF)) 948175294Sattilio VOP_UNLOCK(dp, 0); 9493148Sphk *vpp = dp; 95054655Seivind /* XXX This should probably move to the top of function. */ 9513148Sphk if (cnp->cn_flags & SAVESTART) 9523148Sphk panic("lookup: SAVESTART"); 9533148Sphk return (0); 9543148Sphk } 9553148Sphk 9563148Sphk if (cnp->cn_flags & ISDOTDOT) 9573148Sphk panic ("relookup: lookup on dot-dot"); 9583148Sphk 9593148Sphk /* 9603148Sphk * We now have a segment name to search for, and a directory to search. 9613148Sphk */ 962138345Sphk#ifdef NAMEI_DIAGNOSTIC 963138345Sphk vprint("search in:", dp); 964138345Sphk#endif 96543311Sdillon if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { 96642408Seivind KASSERT(*vpp == NULL, ("leaf should be empty")); 9673148Sphk if (error != EJUSTRETURN) 9683148Sphk goto bad; 9693148Sphk /* 9703148Sphk * If creating and at end of pathname, then can consider 9713148Sphk * allowing file to be created. 9723148Sphk */ 97311644Sdg if (rdonly) { 9743148Sphk error = EROFS; 9753148Sphk goto bad; 9763148Sphk } 9773148Sphk /* ASSERT(dvp == ndp->ni_startdir) */ 9783148Sphk if (cnp->cn_flags & SAVESTART) 9793148Sphk VREF(dvp); 980144203Sjeff if ((cnp->cn_flags & LOCKPARENT) == 0) 981175294Sattilio VOP_UNLOCK(dp, 0); 9823148Sphk /* 983144203Sjeff * This is a temporary assert to make sure I know what the 984144203Sjeff * behavior here was. 985144203Sjeff */ 986144203Sjeff KASSERT((cnp->cn_flags & (WANTPARENT|LOCKPARENT)) != 0, 987144203Sjeff ("relookup: Unhandled case.")); 988144203Sjeff /* 9893148Sphk * We return with ni_vp NULL to indicate that the entry 9903148Sphk * doesn't currently exist, leaving a pointer to the 991161010Srwatson * (possibly locked) directory vnode in ndp->ni_dvp. 9923148Sphk */ 9933148Sphk return (0); 9943148Sphk } 995162288Smohans 9963148Sphk dp = *vpp; 9973148Sphk 9983148Sphk /* 99996755Strhodes * Disallow directory write attempts on read-only filesystems. 10003148Sphk */ 100111644Sdg if (rdonly && 100211644Sdg (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 1003145004Sjeff if (dvp == dp) 1004145004Sjeff vrele(dvp); 1005145004Sjeff else 1006145004Sjeff vput(dvp); 100711644Sdg error = EROFS; 1008145004Sjeff goto bad; 10093148Sphk } 1010145004Sjeff /* 1011145004Sjeff * Set the parent lock/ref state to the requested state. 1012145004Sjeff */ 1013145004Sjeff if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { 1014145004Sjeff if (wantparent) 1015175294Sattilio VOP_UNLOCK(dvp, 0); 1016145004Sjeff else 1017145004Sjeff vput(dvp); 1018145004Sjeff } else if (!wantparent) 1019145004Sjeff vrele(dvp); 1020145004Sjeff /* 1021145004Sjeff * Check for symbolic link 1022145004Sjeff */ 1023145004Sjeff KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), 1024145004Sjeff ("relookup: symlink found.\n")); 1025145004Sjeff 10263148Sphk /* ASSERT(dvp == ndp->ni_startdir) */ 10273148Sphk if (cnp->cn_flags & SAVESTART) 10283148Sphk VREF(dvp); 102922521Sdyson 10303148Sphk if ((cnp->cn_flags & LOCKLEAF) == 0) 1031175294Sattilio VOP_UNLOCK(dp, 0); 10323148Sphk return (0); 10333148Sphkbad: 10343148Sphk vput(dp); 10353148Sphk *vpp = NULL; 10363148Sphk return (error); 10373148Sphk} 1038141471Sjhb 1039141471Sjhb/* 1040144661Sjeff * Free data allocated by namei(); see namei(9) for details. 1041144661Sjeff */ 1042144661Sjeffvoid 1043161011SrwatsonNDFREE(struct nameidata *ndp, const u_int flags) 1044144661Sjeff{ 1045144833Sjeff int unlock_dvp; 1046144833Sjeff int unlock_vp; 1047144661Sjeff 1048144833Sjeff unlock_dvp = 0; 1049144833Sjeff unlock_vp = 0; 1050144833Sjeff 1051144661Sjeff if (!(flags & NDF_NO_FREE_PNBUF) && 1052144661Sjeff (ndp->ni_cnd.cn_flags & HASBUF)) { 1053144661Sjeff uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 1054144661Sjeff ndp->ni_cnd.cn_flags &= ~HASBUF; 1055144661Sjeff } 1056144833Sjeff if (!(flags & NDF_NO_VP_UNLOCK) && 1057144833Sjeff (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) 1058144833Sjeff unlock_vp = 1; 1059144833Sjeff if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { 1060144833Sjeff if (unlock_vp) { 1061144833Sjeff vput(ndp->ni_vp); 1062144833Sjeff unlock_vp = 0; 1063144833Sjeff } else 1064144833Sjeff vrele(ndp->ni_vp); 1065144833Sjeff ndp->ni_vp = NULL; 1066144833Sjeff } 1067144833Sjeff if (unlock_vp) 1068175294Sattilio VOP_UNLOCK(ndp->ni_vp, 0); 1069144661Sjeff if (!(flags & NDF_NO_DVP_UNLOCK) && 1070144661Sjeff (ndp->ni_cnd.cn_flags & LOCKPARENT) && 1071144661Sjeff ndp->ni_dvp != ndp->ni_vp) 1072144833Sjeff unlock_dvp = 1; 1073144661Sjeff if (!(flags & NDF_NO_DVP_RELE) && 1074144661Sjeff (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { 1075144833Sjeff if (unlock_dvp) { 1076144833Sjeff vput(ndp->ni_dvp); 1077144833Sjeff unlock_dvp = 0; 1078144833Sjeff } else 1079144833Sjeff vrele(ndp->ni_dvp); 1080144661Sjeff ndp->ni_dvp = NULL; 1081144661Sjeff } 1082144833Sjeff if (unlock_dvp) 1083175294Sattilio VOP_UNLOCK(ndp->ni_dvp, 0); 1084144661Sjeff if (!(flags & NDF_NO_STARTDIR_RELE) && 1085144661Sjeff (ndp->ni_cnd.cn_flags & SAVESTART)) { 1086144661Sjeff vrele(ndp->ni_startdir); 1087144661Sjeff ndp->ni_startdir = NULL; 1088144661Sjeff } 1089144661Sjeff} 1090144661Sjeff 1091144661Sjeff/* 1092141471Sjhb * Determine if there is a suitable alternate filename under the specified 1093141471Sjhb * prefix for the specified path. If the create flag is set, then the 1094141471Sjhb * alternate prefix will be used so long as the parent directory exists. 1095141471Sjhb * This is used by the various compatiblity ABIs so that Linux binaries prefer 1096141471Sjhb * files under /compat/linux for example. The chosen path (whether under 1097141471Sjhb * the prefix or under /) is returned in a kernel malloc'd buffer pointed 1098141471Sjhb * to by pathbuf. The caller is responsible for free'ing the buffer from 1099141471Sjhb * the M_TEMP bucket if one is returned. 1100141471Sjhb */ 1101141471Sjhbint 1102177997Skibkern_alternate_path(struct thread *td, const char *prefix, const char *path, 1103177997Skib enum uio_seg pathseg, char **pathbuf, int create, int dirfd) 1104141471Sjhb{ 1105141471Sjhb struct nameidata nd, ndroot; 1106141471Sjhb char *ptr, *buf, *cp; 1107141471Sjhb size_t len, sz; 1108141471Sjhb int error; 1109141471Sjhb 1110141471Sjhb buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 1111141471Sjhb *pathbuf = buf; 1112141471Sjhb 1113141471Sjhb /* Copy the prefix into the new pathname as a starting point. */ 1114141471Sjhb len = strlcpy(buf, prefix, MAXPATHLEN); 1115141471Sjhb if (len >= MAXPATHLEN) { 1116141471Sjhb *pathbuf = NULL; 1117141471Sjhb free(buf, M_TEMP); 1118141471Sjhb return (EINVAL); 1119141471Sjhb } 1120141471Sjhb sz = MAXPATHLEN - len; 1121141471Sjhb ptr = buf + len; 1122141471Sjhb 1123141471Sjhb /* Append the filename to the prefix. */ 1124141471Sjhb if (pathseg == UIO_SYSSPACE) 1125141471Sjhb error = copystr(path, ptr, sz, &len); 1126141471Sjhb else 1127141471Sjhb error = copyinstr(path, ptr, sz, &len); 1128141471Sjhb 1129141471Sjhb if (error) { 1130141471Sjhb *pathbuf = NULL; 1131141471Sjhb free(buf, M_TEMP); 1132141471Sjhb return (error); 1133141471Sjhb } 1134141471Sjhb 1135141471Sjhb /* Only use a prefix with absolute pathnames. */ 1136141471Sjhb if (*ptr != '/') { 1137141471Sjhb error = EINVAL; 1138141471Sjhb goto keeporig; 1139141471Sjhb } 1140141471Sjhb 1141177997Skib if (dirfd != AT_FDCWD) { 1142177997Skib /* 1143177997Skib * We want the original because the "prefix" is 1144177997Skib * included in the already opened dirfd. 1145177997Skib */ 1146177997Skib bcopy(ptr, buf, len); 1147177997Skib return (0); 1148177997Skib } 1149177997Skib 1150141471Sjhb /* 1151141471Sjhb * We know that there is a / somewhere in this pathname. 1152141471Sjhb * Search backwards for it, to find the file's parent dir 1153141471Sjhb * to see if it exists in the alternate tree. If it does, 1154141471Sjhb * and we want to create a file (cflag is set). We don't 1155141471Sjhb * need to worry about the root comparison in this case. 1156141471Sjhb */ 1157141471Sjhb 1158141471Sjhb if (create) { 1159141471Sjhb for (cp = &ptr[len] - 1; *cp != '/'; cp--); 1160141471Sjhb *cp = '\0'; 1161141471Sjhb 1162150431Sjhb NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1163141471Sjhb error = namei(&nd); 1164141471Sjhb *cp = '/'; 1165141471Sjhb if (error != 0) 1166150431Sjhb goto keeporig; 1167141471Sjhb } else { 1168150431Sjhb NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); 1169141471Sjhb 1170141471Sjhb error = namei(&nd); 1171141471Sjhb if (error != 0) 1172150431Sjhb goto keeporig; 1173141471Sjhb 1174141471Sjhb /* 1175141471Sjhb * We now compare the vnode of the prefix to the one 1176141471Sjhb * vnode asked. If they resolve to be the same, then we 1177141471Sjhb * ignore the match so that the real root gets used. 1178141471Sjhb * This avoids the problem of traversing "../.." to find the 1179141471Sjhb * root directory and never finding it, because "/" resolves 1180141471Sjhb * to the emulation root directory. This is expensive :-( 1181141471Sjhb */ 1182150431Sjhb NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix, 1183150431Sjhb td); 1184141471Sjhb 1185141471Sjhb /* We shouldn't ever get an error from this namei(). */ 1186141471Sjhb error = namei(&ndroot); 1187141471Sjhb if (error == 0) { 1188141471Sjhb if (nd.ni_vp == ndroot.ni_vp) 1189141471Sjhb error = ENOENT; 1190141471Sjhb 1191141471Sjhb NDFREE(&ndroot, NDF_ONLY_PNBUF); 1192141471Sjhb vrele(ndroot.ni_vp); 1193150431Sjhb VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot)); 1194141471Sjhb } 1195141471Sjhb } 1196141471Sjhb 1197141471Sjhb NDFREE(&nd, NDF_ONLY_PNBUF); 1198141471Sjhb vrele(nd.ni_vp); 1199150431Sjhb VFS_UNLOCK_GIANT(NDHASGIANT(&nd)); 1200141471Sjhb 1201141471Sjhbkeeporig: 1202141471Sjhb /* If there was an error, use the original path name. */ 1203141471Sjhb if (error) 1204141471Sjhb bcopy(ptr, buf, len); 1205141471Sjhb return (error); 1206141471Sjhb} 1207