/* $OpenBSD: vfs_lookup.c,v 1.5 1996/11/06 06:51:45 tholo Exp $ */ /* $NetBSD: vfs_lookup.c,v 1.17 1996/02/09 19:00:59 christos 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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 8.6 (Berkeley) 11/21/94 */ #include <sys/param.h> #include <sys/systm.h> #include <sys/syslimits.h> #include <sys/time.h> #include <sys/namei.h> #include <sys/vnode.h> #include <sys/mount.h> #include <sys/errno.h> #include <sys/malloc.h> #include <sys/filedesc.h> #include <sys/proc.h> #ifdef KTRACE #include <sys/ktrace.h> #endif /* * Convert a pathname into a pointer to a locked inode. * * 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(ndp) register struct nameidata *ndp; { register struct filedesc *fdp; /* pointer to file descriptor state */ register char *cp; /* pointer into pathname argument */ register struct vnode *dp; /* the directory we are searching */ struct iovec aiov; /* uio for reading symbolic links */ struct uio auio; int error, linklen, dironly = 0; struct componentname *cnp = &ndp->ni_cnd; ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_proc->p_ucred; #ifdef DIAGNOSTIC if (!cnp->cn_cred || !cnp->cn_proc) 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 fdp = cnp->cn_proc->p_fd; /* * Get a buffer for the name to be translated, and copy the * name into the buffer. */ if ((cnp->cn_flags & HASBUF) == 0) MALLOC(cnp->cn_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK); 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); #ifdef KTRACE if (KTRPOINT(cnp->cn_proc, KTR_NAMEI)) ktrnamei(cnp->cn_proc->p_tracep, cnp->cn_pnbuf); #endif /* * Fail on null pathnames */ if (error == 0 && ndp->ni_pathlen == 1) error = ENOENT; if (error) { free(cnp->cn_pnbuf, M_NAMEI); ndp->ni_vp = NULL; return (error); } /* * Ignore trailing /'s, except require the last path element * to be a directory */ if (ndp->ni_pathlen > 2 && cnp->cn_pnbuf[ndp->ni_pathlen - 2] == '/') { /* * Since the last name is no longer the terminal, * force the FOLLOW flag */ cnp->cn_flags |= FOLLOW; dironly = 1; while (ndp->ni_pathlen > 2 && cnp->cn_pnbuf[ndp->ni_pathlen - 2] == '/') cnp->cn_pnbuf[--ndp->ni_pathlen - 1] = '\0'; } ndp->ni_loopcnt = 0; /* * Get starting point for the translation. */ if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL) ndp->ni_rootdir = rootvnode; dp = fdp->fd_cdir; VREF(dp); for (;;) { /* * Check if root directory should replace current directory. * Done at start of translation and after symbolic link. */ cnp->cn_nameptr = cnp->cn_pnbuf; if (*(cnp->cn_nameptr) == '/') { vrele(dp); while (*(cnp->cn_nameptr) == '/') { cnp->cn_nameptr++; ndp->ni_pathlen--; } dp = ndp->ni_rootdir; VREF(dp); } ndp->ni_startdir = dp; if ((error = lookup(ndp)) != 0) { FREE(cnp->cn_pnbuf, M_NAMEI); return (error); } /* * Check for symbolic link */ if ((cnp->cn_flags & ISSYMLINK) == 0) { /* * Check for directory if dironly */ if (dironly && ndp->ni_vp->v_type != VDIR) { if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1) VOP_UNLOCK(ndp->ni_dvp); vput(ndp->ni_vp); FREE(cnp->cn_pnbuf, M_NAMEI); return (ENOTDIR); } if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) FREE(cnp->cn_pnbuf, M_NAMEI); else cnp->cn_flags |= HASBUF; return (0); } if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1) VOP_UNLOCK(ndp->ni_dvp); if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { error = ELOOP; break; } if (ndp->ni_pathlen > 1) MALLOC(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK); 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_segflg = UIO_SYSSPACE; auio.uio_procp = (struct proc *)0; auio.uio_resid = MAXPATHLEN; error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); if (error) { if (ndp->ni_pathlen > 1) free(cp, M_NAMEI); break; } linklen = MAXPATHLEN - auio.uio_resid; if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { if (ndp->ni_pathlen > 1) free(cp, M_NAMEI); error = ENAMETOOLONG; break; } if (ndp->ni_pathlen > 1) { bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); FREE(cnp->cn_pnbuf, M_NAMEI); cnp->cn_pnbuf = cp; } else cnp->cn_pnbuf[linklen] = '\0'; ndp->ni_pathlen += linklen; vput(ndp->ni_vp); dp = ndp->ni_dvp; } FREE(cnp->cn_pnbuf, M_NAMEI); vrele(ndp->ni_dvp); vput(ndp->ni_vp); ndp->ni_vp = NULL; return (error); } /* * 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. If flag has WANTPARENT or'ed into it, the parent directory is * returned unlocked. 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, unlocked unless LOCKPARENT set * 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 * if WANTPARENT set, return unlocked parent in ni_dvp */ int lookup(ndp) register struct nameidata *ndp; { register char *cp; /* pointer into pathname argument */ register 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 wantparent; /* 1 => wantparent or lockparent flag */ int rdonly; /* lookup read-only flag bit */ int error = 0; struct componentname *cnp = &ndp->ni_cnd; /* * Setup: break out flag bits into variables. */ wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; if (cnp->cn_nameiop == DELETE || (wantparent && cnp->cn_nameiop != CREATE)) docache = 0; rdonly = cnp->cn_flags & RDONLY; ndp->ni_dvp = NULL; cnp->cn_flags &= ~ISSYMLINK; dp = ndp->ni_startdir; ndp->ni_startdir = NULLVP; VOP_LOCK(dp); 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. */ cnp->cn_consume = 0; cnp->cn_hash = 0; for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) cnp->cn_hash += (unsigned char)*cp; cnp->cn_namelen = cp - cnp->cn_nameptr; if (cnp->cn_namelen > NAME_MAX) { error = ENAMETOOLONG; goto bad; } #ifdef NAMEI_DIAGNOSTIC { char c = *cp; *cp = '\0'; printf("{%s}: ", cnp->cn_nameptr); *cp = c; } #endif ndp->ni_pathlen -= cnp->cn_namelen; ndp->ni_next = cp; cnp->cn_flags |= MAKEENTRY; if (*cp == '\0' && docache == 0) cnp->cn_flags &= ~MAKEENTRY; if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.') cnp->cn_flags |= ISDOTDOT; else cnp->cn_flags &= ~ISDOTDOT; if (*ndp->ni_next == 0) cnp->cn_flags |= ISLASTCN; else cnp->cn_flags &= ~ISLASTCN; /* * 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') { if (dp->v_type != VDIR) { error = ENOTDIR; goto bad; } if (cnp->cn_nameiop != LOOKUP) { error = EISDIR; goto bad; } if (wantparent) { ndp->ni_dvp = dp; VREF(dp); } ndp->ni_vp = dp; if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) VOP_UNLOCK(dp); if (cnp->cn_flags & SAVESTART) panic("lookup: SAVESTART"); return (0); } /* * 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. * 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) { for (;;) { if (dp == ndp->ni_rootdir || dp == rootvnode) { ndp->ni_dvp = dp; ndp->ni_vp = dp; VREF(dp); goto nextname; } if ((dp->v_flag & VROOT) == 0 || (cnp->cn_flags & NOCROSSMOUNT)) break; tdp = dp; dp = dp->v_mount->mnt_vnodecovered; vput(tdp); VREF(dp); VOP_LOCK(dp); } } /* * We now have a segment name to search for, and a directory to search. */ unionlookup: ndp->ni_dvp = dp; if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { #ifdef DIAGNOSTIC if (ndp->ni_vp != NULL) panic("leaf should be empty"); #endif #ifdef NAMEI_DIAGNOSTIC printf("not found\n"); #endif if ((error == ENOENT) && (dp->v_flag & VROOT) && (dp->v_mount->mnt_flag & MNT_UNION)) { tdp = dp; dp = dp->v_mount->mnt_vnodecovered; vput(tdp); VREF(dp); VOP_LOCK(dp); goto unionlookup; } if (error != EJUSTRETURN) goto bad; /* * If creating and at end of pathname, then can consider * allowing file to be created. */ if (rdonly || (ndp->ni_dvp->v_mount->mnt_flag & MNT_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 inode 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 /* * Take into account any additional components consumed by * the underlying filesystem. */ if (cnp->cn_consume > 0) { cnp->cn_nameptr += cnp->cn_consume; ndp->ni_next += cnp->cn_consume; ndp->ni_pathlen -= cnp->cn_consume; cnp->cn_consume = 0; } dp = ndp->ni_vp; /* * 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 (mp->mnt_flag & MNT_MLOCK) { mp->mnt_flag |= MNT_MWAIT; sleep((caddr_t)mp, PVFS); continue; } if ((error = VFS_ROOT(dp->v_mountedhere, &tdp)) != 0) goto bad2; vput(dp); ndp->ni_vp = dp = tdp; } /* * Check for symbolic link */ if ((dp->v_type == VLNK) && ((cnp->cn_flags & FOLLOW) || *ndp->ni_next == '/')) { cnp->cn_flags |= ISSYMLINK; return (0); } nextname: /* * Not a symbolic link. If more pathname, * continue at next component, else return. */ if (*ndp->ni_next == '/') { cnp->cn_nameptr = ndp->ni_next; while (*cnp->cn_nameptr == '/') { cnp->cn_nameptr++; ndp->ni_pathlen--; } vrele(ndp->ni_dvp); goto dirloop; } /* * Check for read-only file systems. */ if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) { /* * Disallow directory write attempts on read-only * file systems. */ if (rdonly || (dp->v_mount->mnt_flag & MNT_RDONLY) || (wantparent && (ndp->ni_dvp->v_mount->mnt_flag & MNT_RDONLY))) { error = EROFS; goto bad2; } } if (cnp->cn_flags & SAVESTART) { ndp->ni_startdir = ndp->ni_dvp; VREF(ndp->ni_startdir); } if (!wantparent) vrele(ndp->ni_dvp); if ((cnp->cn_flags & LOCKLEAF) == 0) VOP_UNLOCK(dp); return (0); bad2: if ((cnp->cn_flags & LOCKPARENT) && *ndp->ni_next == '\0') VOP_UNLOCK(ndp->ni_dvp); vrele(ndp->ni_dvp); bad: vput(dp); ndp->ni_vp = NULL; return (error); } /* * Reacquire a path name component. */ int relookup(dvp, vpp, cnp) struct vnode *dvp, **vpp; struct componentname *cnp; { register struct vnode *dp = 0; /* the directory we are searching */ int docache; /* == 0 do not cache last component */ int wantparent; /* 1 => wantparent or lockparent flag */ int rdonly; /* lookup read-only flag bit */ int error = 0; #ifdef NAMEI_DIAGNOSTIC int newhash; /* DEBUG: check name hash */ char *cp; /* DEBUG: check name ptr/len */ #endif /* * Setup: break out flag bits into variables. */ wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; if (cnp->cn_nameiop == DELETE || (wantparent && cnp->cn_nameiop != CREATE)) docache = 0; rdonly = cnp->cn_flags & RDONLY; cnp->cn_flags &= ~ISSYMLINK; dp = dvp; VOP_LOCK(dp); /* 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. */ #ifdef NAMEI_DIAGNOSTIC for (newhash = 0, cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) newhash += (unsigned char)*cp; if (newhash != cnp->cn_hash) panic("relookup: bad hash"); if (cnp->cn_namelen != cp - cnp->cn_nameptr) panic ("relookup: bad len"); if (*cp != 0) panic("relookup: not last component"); printf("{%s}: ", cnp->cn_nameptr); #endif /* * 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') { if (dp->v_type != VDIR) { error = ENOTDIR; goto bad; } if (cnp->cn_nameiop != LOOKUP || wantparent) { error = EISDIR; goto bad; } if (!(cnp->cn_flags & LOCKLEAF)) VOP_UNLOCK(dp); *vpp = dp; if (cnp->cn_flags & SAVESTART) panic("lookup: SAVESTART"); return (0); } 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(dp, vpp, cnp)) != 0) { #ifdef DIAGNOSTIC if (*vpp != NULL) panic("leaf should be empty"); #endif if (error != EJUSTRETURN) goto bad; /* * If creating and at end of pathname, then can consider * allowing file to be created. */ if (rdonly || (dvp->v_mount->mnt_flag & MNT_RDONLY)) { error = EROFS; goto bad; } /* ASSERT(dvp == ndp->ni_startdir) */ if (cnp->cn_flags & SAVESTART) VREF(dvp); /* * We return with ni_vp NULL to indicate that the entry * doesn't currently exist, leaving a pointer to the * (possibly locked) directory inode in ndp->ni_dvp. */ return (0); } dp = *vpp; #ifdef DIAGNOSTIC /* * Check for symbolic link */ if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW)) panic ("relookup: symlink found.\n"); #endif /* * Check for read-only file systems. */ if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME) { /* * Disallow directory write attempts on read-only * file systems. */ if (rdonly || (dp->v_mount->mnt_flag & MNT_RDONLY) || (wantparent && (dvp->v_mount->mnt_flag & MNT_RDONLY))) { error = EROFS; goto bad2; } } /* ASSERT(dvp == ndp->ni_startdir) */ if (cnp->cn_flags & SAVESTART) VREF(dvp); if (!wantparent) vrele(dvp); if ((cnp->cn_flags & LOCKLEAF) == 0) VOP_UNLOCK(dp); return (0); bad2: if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN)) VOP_UNLOCK(dvp); vrele(dvp); bad: vput(dp); *vpp = NULL; return (error); }