/* $NetBSD: vfs_lookup.c,v 1.100 2007/11/26 19:02:07 pooka Exp $ */ /* * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)vfs_lookup.c 8.10 (Berkeley) 5/27/95 */ #include __KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.100 2007/11/26 19:02:07 pooka Exp $"); #include "opt_systrace.h" #include "opt_magiclinks.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef SYSTRACE #include #endif #ifndef MAGICLINKS #define MAGICLINKS 0 #endif struct pathname_internal { char *pathbuf; bool needfree; }; int vfs_magiclinks = MAGICLINKS; pool_cache_t pnbuf_cache; /* pathname buffer cache */ /* * Substitute replacement text for 'magic' strings in symlinks. * Returns 0 if successful, and returns non-zero if an error * occurs. (Currently, the only possible error is running out * of temporary pathname space.) * * Looks for "@" and "@/", where is a * recognized 'magic' string. Replaces the "@" with the * appropriate replacement text. (Note that in some cases the * replacement text may have zero length.) * * This would have been table driven, but the variance in * replacement strings (and replacement string lengths) made * that impractical. */ #define VNL(x) \ (sizeof(x) - 1) #define VO '{' #define VC '}' #define MATCH(str) \ ((termchar == '/' && i + VNL(str) == *len) || \ (i + VNL(str) < *len && \ cp[i + VNL(str)] == termchar)) && \ !strncmp((str), &cp[i], VNL(str)) #define SUBSTITUTE(m, s, sl) \ if ((newlen + (sl)) > MAXPATHLEN) \ return (1); \ i += VNL(m); \ if (termchar != '/') \ i++; \ memcpy(&tmp[newlen], (s), (sl)); \ newlen += (sl); \ change = 1; \ termchar = '/'; static int symlink_magic(struct proc *p, char *cp, int *len) { char *tmp; int change, i, newlen; int termchar = '/'; tmp = PNBUF_GET(); for (change = i = newlen = 0; i < *len; ) { if (cp[i] != '@') { tmp[newlen++] = cp[i++]; continue; } i++; /* Check for @{var} syntax. */ if (cp[i] == VO) { termchar = VC; i++; } /* * The following checks should be ordered according * to frequency of use. */ if (MATCH("machine_arch")) { SUBSTITUTE("machine_arch", MACHINE_ARCH, sizeof(MACHINE_ARCH) - 1); } else if (MATCH("machine")) { SUBSTITUTE("machine", MACHINE, sizeof(MACHINE) - 1); } else if (MATCH("hostname")) { SUBSTITUTE("hostname", hostname, hostnamelen); } else if (MATCH("osrelease")) { SUBSTITUTE("osrelease", osrelease, strlen(osrelease)); } else if (MATCH("emul")) { SUBSTITUTE("emul", p->p_emul->e_name, strlen(p->p_emul->e_name)); } else if (MATCH("kernel_ident")) { SUBSTITUTE("kernel_ident", kernel_ident, strlen(kernel_ident)); } else if (MATCH("domainname")) { SUBSTITUTE("domainname", domainname, domainnamelen); } else if (MATCH("ostype")) { SUBSTITUTE("ostype", ostype, strlen(ostype)); } else if (MATCH("uid")) { char uidtmp[11]; /* XXX elad */ (void)snprintf(uidtmp, sizeof(uidtmp), "%u", kauth_cred_geteuid(kauth_cred_get())); SUBSTITUTE("uid", uidtmp, strlen(uidtmp)); } else { tmp[newlen++] = '@'; if (termchar == VC) tmp[newlen++] = VO; } } if (change) { memcpy(cp, tmp, newlen); *len = newlen; } PNBUF_PUT(tmp); return (0); } #undef VNL #undef VO #undef VC #undef MATCH #undef SUBSTITUTE /* * Convert a pathname into a pointer to a locked vnode. * * The FOLLOW flag is set when symbolic links are to be followed * when they occur at the end of the name translation process. * Symbolic links are always followed for all other pathname * components other than the last. * * The segflg defines whether the name is to be copied from user * space or kernel space. * * Overall outline of namei: * * copy in name * get starting directory * while (!done && !error) { * call lookup to search path. * if symbolic link, massage name in buffer and continue * } */ int namei(struct nameidata *ndp) { struct cwdinfo *cwdi; /* pointer to cwd state */ char *cp; /* pointer into pathname argument */ struct vnode *dp; /* the directory we are searching */ struct iovec aiov; /* uio for reading symbolic links */ struct uio auio; int error, linklen; struct componentname *cnp = &ndp->ni_cnd; #ifdef DIAGNOSTIC if (!cnp->cn_cred || !cnp->cn_lwp) panic("namei: bad cred/proc"); if (cnp->cn_nameiop & (~OPMASK)) panic("namei: nameiop contaminated with flags"); if (cnp->cn_flags & OPMASK) panic("namei: flags contaminated with nameiops"); #endif /* * Get a buffer for the name to be translated, and copy the * name into the buffer. */ if ((cnp->cn_flags & HASBUF) == 0) cnp->cn_pnbuf = PNBUF_GET(); emul_retry: if (ndp->ni_segflg == UIO_SYSSPACE) error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, &ndp->ni_pathlen); else error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, &ndp->ni_pathlen); /* * POSIX.1 requirement: "" is not a valid file name. */ if (!error && ndp->ni_pathlen == 1) error = ENOENT; if (error) { PNBUF_PUT(cnp->cn_pnbuf); ndp->ni_vp = NULL; return (error); } ndp->ni_loopcnt = 0; /* * Get root directory for the translation. */ cwdi = cnp->cn_lwp->l_proc->p_cwdi; rw_enter(&cwdi->cwdi_lock, RW_READER); dp = cwdi->cwdi_rdir; if (dp == NULL) dp = rootvnode; ndp->ni_rootdir = dp; /* * Check if starting from root directory or current directory. */ if (cnp->cn_pnbuf[0] == '/') { if (cnp->cn_flags & TRYEMULROOT) { if (cnp->cn_flags & EMULROOTSET) { /* Called from (eg) emul_find_interp() */ dp = ndp->ni_erootdir; } else { if (cwdi->cwdi_edir == NULL || (cnp->cn_pnbuf[1] == '.' && cnp->cn_pnbuf[2] == '.' && cnp->cn_pnbuf[3] == '/')) { ndp->ni_erootdir = NULL; } else { dp = cwdi->cwdi_edir; ndp->ni_erootdir = dp; } } } else ndp->ni_erootdir = NULL; } else { dp = cwdi->cwdi_cdir; ndp->ni_erootdir = NULL; } VREF(dp); rw_exit(&cwdi->cwdi_lock); if (ktrpoint(KTR_NAMEI)) { if (ndp->ni_erootdir != NULL) { /* * To make any sense, the trace entry need to have the * text of the emulation path prepended. * Usually we can get this from the current process, * but when called from emul_find_interp() it is only * in the exec_package - so we get it passed in ni_next * (this is a hack). */ const char *emul_path; if (cnp->cn_flags & EMULROOTSET) emul_path = ndp->ni_next; else emul_path = cnp->cn_lwp->l_proc->p_emul->e_path; ktrnamei2(emul_path, strlen(emul_path), cnp->cn_pnbuf, ndp->ni_pathlen); } else ktrnamei(cnp->cn_pnbuf, ndp->ni_pathlen); } #ifdef SYSTRACE if (ISSET(cnp->cn_lwp->l_proc->p_flag, PK_SYSTRACE)) systrace_namei(ndp); #endif vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); /* Loop through symbolic links */ for (;;) { if (!dp->v_mount) { /* Give up if the directory is no longer mounted */ vput(dp); PNBUF_PUT(cnp->cn_pnbuf); return (ENOENT); } cnp->cn_nameptr = cnp->cn_pnbuf; ndp->ni_startdir = dp; error = lookup(ndp); if (error != 0) { if (ndp->ni_dvp) { vput(ndp->ni_dvp); } if (ndp->ni_erootdir != NULL) { /* Retry the whole thing from the normal root */ cnp->cn_flags &= ~TRYEMULROOT; goto emul_retry; } PNBUF_PUT(cnp->cn_pnbuf); return (error); } /* * Check for symbolic link */ if ((cnp->cn_flags & ISSYMLINK) == 0) { if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp) { if (ndp->ni_dvp == ndp->ni_vp) { vrele(ndp->ni_dvp); } else { vput(ndp->ni_dvp); } } if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) PNBUF_PUT(cnp->cn_pnbuf); else cnp->cn_flags |= HASBUF; return (0); } if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { error = ELOOP; break; } if (ndp->ni_vp->v_mount->mnt_flag & MNT_SYMPERM) { error = VOP_ACCESS(ndp->ni_vp, VEXEC, cnp->cn_cred); if (error != 0) break; } if (ndp->ni_pathlen > 1) cp = PNBUF_GET(); else cp = cnp->cn_pnbuf; aiov.iov_base = cp; aiov.iov_len = MAXPATHLEN; auio.uio_iov = &aiov; auio.uio_iovcnt = 1; auio.uio_offset = 0; auio.uio_rw = UIO_READ; auio.uio_resid = MAXPATHLEN; UIO_SETUP_SYSSPACE(&auio); error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); if (error) { badlink: if (ndp->ni_pathlen > 1) PNBUF_PUT(cp); break; } linklen = MAXPATHLEN - auio.uio_resid; if (linklen == 0) { error = ENOENT; goto badlink; } /* * Do symlink substitution, if appropriate, and * check length for potential overflow. */ if ((vfs_magiclinks && symlink_magic(cnp->cn_lwp->l_proc, cp, &linklen)) || (linklen + ndp->ni_pathlen >= MAXPATHLEN)) { error = ENAMETOOLONG; goto badlink; } if (ndp->ni_pathlen > 1) { memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen); PNBUF_PUT(cnp->cn_pnbuf); cnp->cn_pnbuf = cp; } else cnp->cn_pnbuf[linklen] = '\0'; ndp->ni_pathlen += linklen; vput(ndp->ni_vp); dp = ndp->ni_dvp; /* * Check if root directory should replace current directory. */ if (cnp->cn_pnbuf[0] == '/') { vput(dp); /* Keep absolute symbolic links inside emulation root */ dp = ndp->ni_erootdir; if (dp == NULL || (cnp->cn_pnbuf[1] == '.' && cnp->cn_pnbuf[2] == '.' && cnp->cn_pnbuf[3] == '/')) { ndp->ni_erootdir = NULL; dp = ndp->ni_rootdir; } VREF(dp); vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); } } /* Failed to process a symbolic link */ KASSERT(ndp->ni_dvp != ndp->ni_vp); vput(ndp->ni_dvp); vput(ndp->ni_vp); ndp->ni_vp = NULL; PNBUF_PUT(cnp->cn_pnbuf); return (error); } /* * Determine the namei hash (for cn_hash) for name. * If *ep != NULL, hash from name to ep-1. * If *ep == NULL, hash from name until the first NUL or '/', and * return the location of this termination character in *ep. * * This function returns an equivalent hash to the MI hash32_strn(). * The latter isn't used because in the *ep == NULL case, determining * the length of the string to the first NUL or `/' and then calling * hash32_strn() involves unnecessary double-handling of the data. */ uint32_t namei_hash(const char *name, const char **ep) { uint32_t hash; hash = HASH32_STR_INIT; if (*ep != NULL) { for (; name < *ep; name++) hash = hash * 33 + *(const uint8_t *)name; } else { for (; *name != '\0' && *name != '/'; name++) hash = hash * 33 + *(const uint8_t *)name; *ep = name; } return (hash + (hash >> 5)); } /* * Search a pathname. * This is a very central and rather complicated routine. * * The pathname is pointed to by ni_ptr and is of length ni_pathlen. * The starting directory is taken from ni_startdir. The pathname is * descended until done, or a symbolic link is encountered. The variable * ni_more is clear if the path is completed; it is set to one if a * symbolic link needing interpretation is encountered. * * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on * whether the name is to be looked up, created, renamed, or deleted. * When CREATE, RENAME, or DELETE is specified, information usable in * creating, renaming, or deleting a directory entry may be calculated. * If flag has LOCKPARENT or'ed into it, the parent directory is returned * locked. Otherwise the parent directory is not returned. If the target * of the pathname exists and LOCKLEAF is or'ed into the flag the target * is returned locked, otherwise it is returned unlocked. When creating * or renaming and LOCKPARENT is specified, the target may not be ".". * When deleting and LOCKPARENT is specified, the target may be ".". * * Overall outline of lookup: * * dirloop: * identify next component of name at ndp->ni_ptr * handle degenerate case where name is null string * if .. and crossing mount points and on mounted filesys, find parent * call VOP_LOOKUP routine for next component name * directory vnode returned in ni_dvp, locked. * component vnode returned in ni_vp (if it exists), locked. * if result vnode is mounted on and crossing mount points, * find mounted on vnode * if more components of name, do next level at dirloop * return the answer in ni_vp, locked if LOCKLEAF set * if LOCKPARENT set, return locked parent in ni_dvp */ int lookup(struct nameidata *ndp) { const char *cp; /* pointer into pathname argument */ struct vnode *dp = 0; /* the directory we are searching */ struct vnode *tdp; /* saved dp */ struct mount *mp; /* mount table entry */ int docache; /* == 0 do not cache last component */ int rdonly; /* lookup read-only flag bit */ int error = 0; int slashes; struct componentname *cnp = &ndp->ni_cnd; struct lwp *l = cnp->cn_lwp; /* * Setup: break out flag bits into variables. */ docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; if (cnp->cn_nameiop == DELETE) docache = 0; rdonly = cnp->cn_flags & RDONLY; ndp->ni_dvp = NULL; cnp->cn_flags &= ~ISSYMLINK; dp = ndp->ni_startdir; ndp->ni_startdir = NULLVP; /* * If we have a leading string of slashes, remove them, and just make * sure the current node is a directory. */ cp = cnp->cn_nameptr; if (*cp == '/') { do { cp++; } while (*cp == '/'); ndp->ni_pathlen -= cp - cnp->cn_nameptr; cnp->cn_nameptr = cp; if (dp->v_type != VDIR) { error = ENOTDIR; vput(dp); goto bad; } /* * If we've exhausted the path name, then just return the * current node. */ if (cnp->cn_nameptr[0] == '\0') { ndp->ni_vp = dp; cnp->cn_flags |= ISLASTCN; goto terminal; } } dirloop: /* * Search a new directory. * * The cn_hash value is for use by vfs_cache. * The last component of the filename is left accessible via * cnp->cn_nameptr for callers that need the name. Callers needing * the name set the SAVENAME flag. When done, they assume * responsibility for freeing the pathname buffer. * * At this point, our only vnode state is that "dp" is held and locked. */ cnp->cn_consume = 0; cp = NULL; cnp->cn_hash = namei_hash(cnp->cn_nameptr, &cp); cnp->cn_namelen = cp - cnp->cn_nameptr; if (cnp->cn_namelen > NAME_MAX) { vput(dp); error = ENAMETOOLONG; ndp->ni_dvp = NULL; goto bad; } #ifdef NAMEI_DIAGNOSTIC { char c = *cp; *(char *)cp = '\0'; printf("{%s}: ", cnp->cn_nameptr); *(char *)cp = c; } #endif /* NAMEI_DIAGNOSTIC */ ndp->ni_pathlen -= cnp->cn_namelen; ndp->ni_next = cp; /* * If this component is followed by a slash, then move the pointer to * the next component forward, and remember that this component must be * a directory. */ if (*cp == '/') { do { cp++; } while (*cp == '/'); slashes = cp - ndp->ni_next; ndp->ni_pathlen -= slashes; ndp->ni_next = cp; cnp->cn_flags |= REQUIREDIR; } else { slashes = 0; cnp->cn_flags &= ~REQUIREDIR; } /* * We do special processing on the last component, whether or not it's * a directory. Cache all intervening lookups, but not the final one. */ if (*cp == '\0') { if (docache) cnp->cn_flags |= MAKEENTRY; else cnp->cn_flags &= ~MAKEENTRY; cnp->cn_flags |= ISLASTCN; } else { cnp->cn_flags |= MAKEENTRY; cnp->cn_flags &= ~ISLASTCN; } if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') cnp->cn_flags |= ISDOTDOT; else cnp->cn_flags &= ~ISDOTDOT; /* * Handle "..": two special cases. * 1. If at root directory (e.g. after chroot) * or at absolute root directory * then ignore it so can't get out. * 1a. If at the root of the emulation filesystem go to the real * root. So "/../" is always absolute. * 1b. If we have somehow gotten out of a jail, warn * and also ignore it so we can't get farther out. * 2. If this vnode is the root of a mounted * filesystem, then replace it with the * vnode which was mounted on so we take the * .. in the other file system. */ if (cnp->cn_flags & ISDOTDOT) { struct proc *p = l->l_proc; for (;;) { if (dp == ndp->ni_rootdir || dp == rootvnode) { ndp->ni_dvp = dp; ndp->ni_vp = dp; VREF(dp); goto nextname; } if (ndp->ni_rootdir != rootvnode) { int retval; VOP_UNLOCK(dp, 0); retval = vn_isunder(dp, ndp->ni_rootdir, l); vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); if (!retval) { /* Oops! We got out of jail! */ log(LOG_WARNING, "chrooted pid %d uid %d (%s) " "detected outside of its chroot\n", p->p_pid, kauth_cred_geteuid(l->l_cred), p->p_comm); /* Put us at the jail root. */ vput(dp); dp = ndp->ni_rootdir; ndp->ni_dvp = dp; ndp->ni_vp = dp; VREF(dp); VREF(dp); vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); goto nextname; } } if ((dp->v_vflag & VV_ROOT) == 0 || (cnp->cn_flags & NOCROSSMOUNT)) break; tdp = dp; dp = dp->v_mount->mnt_vnodecovered; vput(tdp); VREF(dp); vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); } } /* * We now have a segment name to search for, and a directory to search. * Again, our only vnode state is that "dp" is held and locked. */ unionlookup: ndp->ni_dvp = dp; ndp->ni_vp = NULL; error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp); if (error != 0) { #ifdef DIAGNOSTIC if (ndp->ni_vp != NULL) panic("leaf `%s' should be empty", cnp->cn_nameptr); #endif /* DIAGNOSTIC */ #ifdef NAMEI_DIAGNOSTIC printf("not found\n"); #endif /* NAMEI_DIAGNOSTIC */ if ((error == ENOENT) && (dp->v_vflag & VV_ROOT) && (dp->v_mount->mnt_flag & MNT_UNION)) { tdp = dp; dp = dp->v_mount->mnt_vnodecovered; vput(tdp); VREF(dp); vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); goto unionlookup; } if (error != EJUSTRETURN) goto bad; /* * If this was not the last component, or there were trailing * slashes, and we are not going to create a directory, * then the name must exist. */ if ((cnp->cn_flags & (REQUIREDIR | CREATEDIR)) == REQUIREDIR) { error = ENOENT; goto bad; } /* * If creating and at end of pathname, then can consider * allowing file to be created. */ if (rdonly) { error = EROFS; goto bad; } /* * We return with ni_vp NULL to indicate that the entry * doesn't currently exist, leaving a pointer to the * (possibly locked) directory vnode in ndp->ni_dvp. */ if (cnp->cn_flags & SAVESTART) { ndp->ni_startdir = ndp->ni_dvp; VREF(ndp->ni_startdir); } return (0); } #ifdef NAMEI_DIAGNOSTIC printf("found\n"); #endif /* NAMEI_DIAGNOSTIC */ /* * Take into account any additional components consumed by the * underlying filesystem. This will include any trailing slashes after * the last component consumed. */ if (cnp->cn_consume > 0) { ndp->ni_pathlen -= cnp->cn_consume - slashes; ndp->ni_next += cnp->cn_consume - slashes; cnp->cn_consume = 0; if (ndp->ni_next[0] == '\0') cnp->cn_flags |= ISLASTCN; } dp = ndp->ni_vp; /* * "dp" and "ndp->ni_dvp" are both locked and held, * and may be the same vnode. */ /* * Check to see if the vnode has been mounted on; * if so find the root of the mounted file system. */ while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && (cnp->cn_flags & NOCROSSMOUNT) == 0) { if (vfs_busy(mp, 0, 0)) continue; KASSERT(ndp->ni_dvp != dp); VOP_UNLOCK(ndp->ni_dvp, 0); vput(dp); error = VFS_ROOT(mp, &tdp); vfs_unbusy(mp); if (error) { vn_lock(ndp->ni_dvp, LK_EXCLUSIVE | LK_RETRY); goto bad; } VOP_UNLOCK(tdp, 0); ndp->ni_vp = dp = tdp; vn_lock(ndp->ni_dvp, LK_EXCLUSIVE | LK_RETRY); vn_lock(ndp->ni_vp, LK_EXCLUSIVE | LK_RETRY); } /* * Check for symbolic link. Back up over any slashes that we skipped, * as we will need them again. */ if ((dp->v_type == VLNK) && (cnp->cn_flags & (FOLLOW|REQUIREDIR))) { ndp->ni_pathlen += slashes; ndp->ni_next -= slashes; cnp->cn_flags |= ISSYMLINK; return (0); } /* * Check for directory, if the component was followed by a series of * slashes. */ if ((dp->v_type != VDIR) && (cnp->cn_flags & REQUIREDIR)) { error = ENOTDIR; KASSERT(dp != ndp->ni_dvp); vput(dp); goto bad; } nextname: /* * Not a symbolic link. If this was not the last component, then * continue at the next component, else return. */ if (!(cnp->cn_flags & ISLASTCN)) { cnp->cn_nameptr = ndp->ni_next; if (ndp->ni_dvp == dp) { vrele(ndp->ni_dvp); } else { vput(ndp->ni_dvp); } goto dirloop; } terminal: if (dp == ndp->ni_erootdir) { /* * We are about to return the emulation root. * This isn't a good idea because code might repeatedly * lookup ".." until the file matches that returned * for "/" and loop forever. * So convert it to the real root. */ if (ndp->ni_dvp == dp) vrele(dp); else if (ndp->ni_dvp != NULL) vput(ndp->ni_dvp); ndp->ni_dvp = NULL; vput(dp); dp = ndp->ni_rootdir; VREF(dp); vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); ndp->ni_vp = dp; } /* * If the caller requested the parent node (i.e. * it's a CREATE, DELETE, or RENAME), and we don't have one * (because this is the root directory), then we must fail. */ if (ndp->ni_dvp == NULL && cnp->cn_nameiop != LOOKUP) { switch (cnp->cn_nameiop) { case CREATE: error = EEXIST; break; case DELETE: case RENAME: error = EBUSY; break; default: KASSERT(0); } vput(dp); goto bad; } /* * Disallow directory write attempts on read-only lookups. * Prefers EEXIST over EROFS for the CREATE case. */ if (rdonly && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { error = EROFS; if (dp != ndp->ni_dvp) { vput(dp); } goto bad; } if (ndp->ni_dvp != NULL) { if (cnp->cn_flags & SAVESTART) { ndp->ni_startdir = ndp->ni_dvp; VREF(ndp->ni_startdir); } } if ((cnp->cn_flags & LOCKLEAF) == 0) { VOP_UNLOCK(dp, 0); } return (0); bad: ndp->ni_vp = NULL; return (error); } /* * Reacquire a path name component. * dvp is locked on entry and exit. * *vpp is locked on exit unless it's NULL. */ int relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) { int rdonly; /* lookup read-only flag bit */ int error = 0; #ifdef DEBUG uint32_t newhash; /* DEBUG: check name hash */ const char *cp; /* DEBUG: check name ptr/len */ #endif /* DEBUG */ /* * Setup: break out flag bits into variables. */ rdonly = cnp->cn_flags & RDONLY; cnp->cn_flags &= ~ISSYMLINK; /* * Search a new directory. * * The cn_hash value is for use by vfs_cache. * The last component of the filename is left accessible via * cnp->cn_nameptr for callers that need the name. Callers needing * the name set the SAVENAME flag. When done, they assume * responsibility for freeing the pathname buffer. */ #ifdef DEBUG cp = NULL; newhash = namei_hash(cnp->cn_nameptr, &cp); if ((uint32_t)newhash != (uint32_t)cnp->cn_hash) panic("relookup: bad hash"); if (cnp->cn_namelen != cp - cnp->cn_nameptr) panic("relookup: bad len"); while (*cp == '/') cp++; if (*cp != 0) panic("relookup: not last component"); #endif /* DEBUG */ /* * Check for degenerate name (e.g. / or "") * which is a way of talking about a directory, * e.g. like "/." or ".". */ if (cnp->cn_nameptr[0] == '\0') panic("relookup: null name"); if (cnp->cn_flags & ISDOTDOT) panic("relookup: lookup on dot-dot"); /* * We now have a segment name to search for, and a directory to search. */ if ((error = VOP_LOOKUP(dvp, vpp, cnp)) != 0) { #ifdef DIAGNOSTIC if (*vpp != NULL) panic("leaf `%s' should be empty", cnp->cn_nameptr); #endif if (error != EJUSTRETURN) goto bad; } #ifdef DIAGNOSTIC /* * Check for symbolic link */ if (*vpp && (*vpp)->v_type == VLNK && (cnp->cn_flags & FOLLOW)) panic("relookup: symlink found"); #endif /* * Check for read-only lookups. */ if (rdonly && cnp->cn_nameiop != LOOKUP) { error = EROFS; if (*vpp) { vput(*vpp); } goto bad; } if (cnp->cn_flags & SAVESTART) VREF(dvp); return (0); bad: *vpp = NULL; return (error); }