/*- * 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. * 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 8.4 (Berkeley) 2/16/94 */ #include __FBSDID("$FreeBSD$"); #include "opt_ktrace.h" #include "opt_mac.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif #include #include #include #define NAMEI_DIAGNOSTIC 1 #undef NAMEI_DIAGNOSTIC /* * Allocation zone for namei */ uma_zone_t namei_zone; /* * Placeholder vnode for mp traversal */ static struct vnode *vp_crossmp; static void nameiinit(void *dummy __unused) { int error; namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); error = getnewvnode("crossmp", NULL, &dead_vnodeops, &vp_crossmp); if (error != 0) panic("nameiinit: getnewvnode"); VN_LOCK_ASHARE(vp_crossmp); } SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL); static int lookup_shared = 1; SYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &lookup_shared, 0, "Enables/Disables shared locks for path name translation"); TUNABLE_INT("vfs.lookup_shared", &lookup_shared); /* * 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 filedesc *fdp; /* pointer to file descriptor 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; struct thread *td = cnp->cn_thread; struct proc *p = td->td_proc; int vfslocked; KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0, ("NOT MPSAFE and Giant not held")); ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_thread->td_ucred; KASSERT(cnp->cn_cred && p, ("namei: bad cred/proc")); KASSERT((cnp->cn_nameiop & (~OPMASK)) == 0, ("namei: nameiop contaminated with flags")); KASSERT((cnp->cn_flags & OPMASK) == 0, ("namei: flags contaminated with nameiops")); if (!lookup_shared) cnp->cn_flags &= ~LOCKSHARED; fdp = p->p_fd; /* * 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 = uma_zalloc(namei_zone, M_WAITOK); if (ndp->ni_segflg == UIO_SYSSPACE) error = copystr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, (size_t *)&ndp->ni_pathlen); else error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf, MAXPATHLEN, (size_t *)&ndp->ni_pathlen); /* If we are auditing the kernel pathname, save the user pathname. */ if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG(upath, td, cnp->cn_pnbuf, ARG_UPATH1); if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG(upath, td, cnp->cn_pnbuf, ARG_UPATH2); /* * Don't allow empty pathnames. */ if (!error && *cnp->cn_pnbuf == '\0') error = ENOENT; if (error) { uma_zfree(namei_zone, cnp->cn_pnbuf); #ifdef DIAGNOSTIC cnp->cn_pnbuf = NULL; cnp->cn_nameptr = NULL; #endif ndp->ni_vp = NULL; return (error); } ndp->ni_loopcnt = 0; #ifdef KTRACE if (KTRPOINT(td, KTR_NAMEI)) { KASSERT(cnp->cn_thread == curthread, ("namei not using curthread")); ktrnamei(cnp->cn_pnbuf); } #endif /* * Get starting point for the translation. */ FILEDESC_SLOCK(fdp); ndp->ni_rootdir = fdp->fd_rdir; ndp->ni_topdir = fdp->fd_jdir; dp = NULL; if (cnp->cn_pnbuf[0] != '/') { if (ndp->ni_startdir != NULL) { dp = ndp->ni_startdir; error = 0; } else if (ndp->ni_dirfd != AT_FDCWD) error = fgetvp(td, ndp->ni_dirfd, &dp); if (error != 0 || dp != NULL) { FILEDESC_SUNLOCK(fdp); if (error == 0 && dp->v_type != VDIR) { vfslocked = VFS_LOCK_GIANT(dp->v_mount); vrele(dp); VFS_UNLOCK_GIANT(vfslocked); error = ENOTDIR; } } if (error) { uma_zfree(namei_zone, cnp->cn_pnbuf); #ifdef DIAGNOSTIC cnp->cn_pnbuf = NULL; cnp->cn_nameptr = NULL; #endif return (error); } } if (dp == NULL) { dp = fdp->fd_cdir; VREF(dp); FILEDESC_SUNLOCK(fdp); if (ndp->ni_startdir != NULL) { vfslocked = VFS_LOCK_GIANT(ndp->ni_startdir->v_mount); vrele(ndp->ni_startdir); VFS_UNLOCK_GIANT(vfslocked); } } vfslocked = VFS_LOCK_GIANT(dp->v_mount); 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); VFS_UNLOCK_GIANT(vfslocked); while (*(cnp->cn_nameptr) == '/') { cnp->cn_nameptr++; ndp->ni_pathlen--; } dp = ndp->ni_rootdir; vfslocked = VFS_LOCK_GIANT(dp->v_mount); VREF(dp); } if (vfslocked) ndp->ni_cnd.cn_flags |= GIANTHELD; ndp->ni_startdir = dp; error = lookup(ndp); if (error) { uma_zfree(namei_zone, cnp->cn_pnbuf); #ifdef DIAGNOSTIC cnp->cn_pnbuf = NULL; cnp->cn_nameptr = NULL; #endif return (error); } vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; ndp->ni_cnd.cn_flags &= ~GIANTHELD; /* * Check for symbolic link */ if ((cnp->cn_flags & ISSYMLINK) == 0) { if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) { uma_zfree(namei_zone, cnp->cn_pnbuf); #ifdef DIAGNOSTIC cnp->cn_pnbuf = NULL; cnp->cn_nameptr = NULL; #endif } else cnp->cn_flags |= HASBUF; if ((cnp->cn_flags & MPSAFE) == 0) { VFS_UNLOCK_GIANT(vfslocked); } else if (vfslocked) ndp->ni_cnd.cn_flags |= GIANTHELD; return (0); } if (ndp->ni_loopcnt++ >= MAXSYMLINKS) { error = ELOOP; break; } #ifdef MAC if ((cnp->cn_flags & NOMACCHECK) == 0) { error = mac_vnode_check_readlink(td->td_ucred, ndp->ni_vp); if (error) break; } #endif if (ndp->ni_pathlen > 1) cp = uma_zalloc(namei_zone, 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_td = (struct thread *)0; auio.uio_resid = MAXPATHLEN; error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred); if (error) { if (ndp->ni_pathlen > 1) uma_zfree(namei_zone, cp); break; } linklen = MAXPATHLEN - auio.uio_resid; if (linklen == 0) { if (ndp->ni_pathlen > 1) uma_zfree(namei_zone, cp); error = ENOENT; break; } if (linklen + ndp->ni_pathlen >= MAXPATHLEN) { if (ndp->ni_pathlen > 1) uma_zfree(namei_zone, cp); error = ENAMETOOLONG; break; } if (ndp->ni_pathlen > 1) { bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen); uma_zfree(namei_zone, 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; } uma_zfree(namei_zone, cnp->cn_pnbuf); #ifdef DIAGNOSTIC cnp->cn_pnbuf = NULL; cnp->cn_nameptr = NULL; #endif vput(ndp->ni_vp); ndp->ni_vp = NULL; vrele(ndp->ni_dvp); VFS_UNLOCK_GIANT(vfslocked); return (error); } static int compute_cn_lkflags(struct mount *mp, int lkflags) { if (mp == NULL || ((lkflags & LK_SHARED) && !(mp->mnt_kern_flag & MNTK_LOOKUP_SHARED))) { lkflags &= ~LK_SHARED; lkflags |= LK_EXCLUSIVE; } return (lkflags); } static __inline int needs_exclusive_leaf(struct mount *mp, int flags) { /* * Intermediate nodes can use shared locks, we only need to * force an exclusive lock for leaf nodes. */ if ((flags & (ISLASTCN | LOCKLEAF)) != (ISLASTCN | LOCKLEAF)) return (0); /* Always use exclusive locks if LOCKSHARED isn't set. */ if (!(flags & LOCKSHARED)) return (1); /* * For lookups during open(), if the mount point supports * extended shared operations, then use a shared lock for the * leaf node, otherwise use an exclusive lock. */ if (flags & ISOPEN) { if (mp != NULL && (mp->mnt_kern_flag & MNTK_EXTENDED_SHARED)) return (0); else return (1); } /* * Lookup requests outside of open() that specify LOCKSHARED * only need a shared lock on the leaf vnode. */ return (0); } /* * 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(struct nameidata *ndp) { 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 wantparent; /* 1 => wantparent or lockparent flag */ int rdonly; /* lookup read-only flag bit */ int trailing_slash; int error = 0; int dpunlocked = 0; /* dp has already been unlocked */ struct componentname *cnp = &ndp->ni_cnd; struct thread *td = cnp->cn_thread; int vfslocked; /* VFS Giant state for child */ int dvfslocked; /* VFS Giant state for parent */ int tvfslocked; int lkflags_save; /* * Setup: break out flag bits into variables. */ dvfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0; vfslocked = 0; ndp->ni_cnd.cn_flags &= ~GIANTHELD; wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT); KASSERT(cnp->cn_nameiop == LOOKUP || wantparent, ("CREATE, DELETE, RENAME require LOCKPARENT or WANTPARENT.")); docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE; if (cnp->cn_nameiop == DELETE || (wantparent && cnp->cn_nameiop != CREATE && cnp->cn_nameiop != LOOKUP)) docache = 0; rdonly = cnp->cn_flags & RDONLY; cnp->cn_flags &= ~ISSYMLINK; ndp->ni_dvp = NULL; /* * We use shared locks until we hit the parent of the last cn then * we adjust based on the requesting flags. */ if (lookup_shared) cnp->cn_lkflags = LK_SHARED; else cnp->cn_lkflags = LK_EXCLUSIVE; dp = ndp->ni_startdir; ndp->ni_startdir = NULLVP; vn_lock(dp, compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); dirloop: /* * Search a new directory. * * 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; for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++) continue; 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; /* * Replace multiple slashes by a single slash and trailing slashes * by a null. This must be done before VOP_LOOKUP() because some * fs's don't know about trailing slashes. Remember if there were * trailing slashes to handle symlinks, existing non-directories * and non-existing files that won't be directories specially later. */ trailing_slash = 0; while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) { cp++; ndp->ni_pathlen--; if (*cp == '\0') { trailing_slash = 1; *ndp->ni_next = '\0'; /* XXX for direnter() ... */ } } 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 & AUDITVNODE1) AUDIT_ARG(vnode, dp, ARG_VNODE1); else if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG(vnode, dp, ARG_VNODE2); if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF))) VOP_UNLOCK(dp, 0); /* XXX This should probably move to the top of function. */ if (cnp->cn_flags & SAVESTART) panic("lookup: SAVESTART"); goto success; } /* * Handle "..": four special cases. * 1. Return an error if this is the last component of * the name and the operation is DELETE or RENAME. * 2. If at root directory (e.g. after chroot) * or at absolute root directory * then ignore it so can't get out. * 3. 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 filesystem. * 4. If the vnode is the top directory of * the jail or chroot, don't let them out. */ if (cnp->cn_flags & ISDOTDOT) { if ((cnp->cn_flags & ISLASTCN) != 0 && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { error = EINVAL; goto bad; } for (;;) { if (dp == ndp->ni_rootdir || dp == ndp->ni_topdir || dp == rootvnode || ((dp->v_vflag & VV_ROOT) != 0 && (cnp->cn_flags & NOCROSSMOUNT) != 0)) { ndp->ni_dvp = dp; ndp->ni_vp = dp; vfslocked = VFS_LOCK_GIANT(dp->v_mount); VREF(dp); goto nextname; } if ((dp->v_vflag & VV_ROOT) == 0) break; if (dp->v_iflag & VI_DOOMED) { /* forced unmount */ error = ENOENT; goto bad; } tdp = dp; dp = dp->v_mount->mnt_vnodecovered; tvfslocked = dvfslocked; dvfslocked = VFS_LOCK_GIANT(dp->v_mount); VREF(dp); vput(tdp); VFS_UNLOCK_GIANT(tvfslocked); vn_lock(dp, compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); } } /* * We now have a segment name to search for, and a directory to search. */ unionlookup: #ifdef MAC if ((cnp->cn_flags & NOMACCHECK) == 0) { error = mac_vnode_check_lookup(td->td_ucred, dp, cnp); if (error) goto bad; } #endif ndp->ni_dvp = dp; ndp->ni_vp = NULL; ASSERT_VOP_LOCKED(dp, "lookup"); VNASSERT(vfslocked == 0, dp, ("lookup: vfslocked %d", vfslocked)); /* * If we have a shared lock we may need to upgrade the lock for the * last operation. */ if (dp != vp_crossmp && VOP_ISLOCKED(dp) == LK_SHARED && (cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT)) vn_lock(dp, LK_UPGRADE|LK_RETRY); /* * If we're looking up the last component and we need an exclusive * lock, adjust our lkflags. */ if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags)) cnp->cn_lkflags = LK_EXCLUSIVE; #ifdef NAMEI_DIAGNOSTIC vprint("lookup in", dp); #endif lkflags_save = cnp->cn_lkflags; cnp->cn_lkflags = compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags); if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) { cnp->cn_lkflags = lkflags_save; KASSERT(ndp->ni_vp == NULL, ("leaf should be empty")); #ifdef NAMEI_DIAGNOSTIC printf("not found\n"); #endif if ((error == ENOENT) && (dp->v_vflag & VV_ROOT) && (dp->v_mount != NULL) && (dp->v_mount->mnt_flag & MNT_UNION)) { tdp = dp; dp = dp->v_mount->mnt_vnodecovered; tvfslocked = dvfslocked; dvfslocked = VFS_LOCK_GIANT(dp->v_mount); VREF(dp); vput(tdp); VFS_UNLOCK_GIANT(tvfslocked); vn_lock(dp, compute_cn_lkflags(dp->v_mount, cnp->cn_lkflags | LK_RETRY)); goto unionlookup; } if (error != EJUSTRETURN) goto bad; /* * If creating and at end of pathname, then can consider * allowing file to be created. */ if (rdonly) { error = EROFS; goto bad; } if (*cp == '\0' && trailing_slash && !(cnp->cn_flags & WILLBEDIR)) { error = ENOENT; goto bad; } if ((cnp->cn_flags & LOCKPARENT) == 0) VOP_UNLOCK(dp, 0); /* * This is a temporary assert to make sure I know what the * behavior here was. */ KASSERT((cnp->cn_flags & (WANTPARENT|LOCKPARENT)) != 0, ("lookup: Unhandled case.")); /* * 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); } goto success; } else cnp->cn_lkflags = lkflags_save; #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; vfslocked = VFS_LOCK_GIANT(dp->v_mount); /* * Check to see if the vnode has been mounted on; * if so find the root of the mounted filesystem. */ while (dp->v_type == VDIR && (mp = dp->v_mountedhere) && (cnp->cn_flags & NOCROSSMOUNT) == 0) { if (vfs_busy(mp, 0)) continue; vput(dp); VFS_UNLOCK_GIANT(vfslocked); vfslocked = VFS_LOCK_GIANT(mp); if (dp != ndp->ni_dvp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); VFS_UNLOCK_GIANT(dvfslocked); dvfslocked = 0; vref(vp_crossmp); ndp->ni_dvp = vp_crossmp; error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags), &tdp, td); vfs_unbusy(mp); if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT)) panic("vp_crossmp exclusively locked or reclaimed"); if (error) { dpunlocked = 1; goto bad2; } ndp->ni_vp = dp = tdp; } /* * Check for symbolic link */ if ((dp->v_type == VLNK) && ((cnp->cn_flags & FOLLOW) || trailing_slash || *ndp->ni_next == '/')) { cnp->cn_flags |= ISSYMLINK; if (dp->v_iflag & VI_DOOMED) { /* * We can't know whether the directory was mounted with * NOSYMFOLLOW, so we can't follow safely. */ error = ENOENT; goto bad2; } if (dp->v_mount->mnt_flag & MNT_NOSYMFOLLOW) { error = EACCES; goto bad2; } /* * Symlink code always expects an unlocked dvp. */ if (ndp->ni_dvp != ndp->ni_vp) VOP_UNLOCK(ndp->ni_dvp, 0); goto success; } /* * Check for bogus trailing slashes. */ if (trailing_slash && dp->v_type != VDIR) { error = ENOTDIR; goto bad2; } nextname: /* * Not a symbolic link. If more pathname, * continue at next component, else return. */ KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/', ("lookup: invalid path state.")); if (*ndp->ni_next == '/') { cnp->cn_nameptr = ndp->ni_next; while (*cnp->cn_nameptr == '/') { cnp->cn_nameptr++; ndp->ni_pathlen--; } if (ndp->ni_dvp != dp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); VFS_UNLOCK_GIANT(dvfslocked); dvfslocked = vfslocked; /* dp becomes dvp in dirloop */ vfslocked = 0; goto dirloop; } /* * Disallow directory write attempts on read-only filesystems. */ if (rdonly && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { error = EROFS; goto bad2; } if (cnp->cn_flags & SAVESTART) { ndp->ni_startdir = ndp->ni_dvp; VREF(ndp->ni_startdir); } if (!wantparent) { if (ndp->ni_dvp != dp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); VFS_UNLOCK_GIANT(dvfslocked); dvfslocked = 0; } else if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp != dp) VOP_UNLOCK(ndp->ni_dvp, 0); if (cnp->cn_flags & AUDITVNODE1) AUDIT_ARG(vnode, dp, ARG_VNODE1); else if (cnp->cn_flags & AUDITVNODE2) AUDIT_ARG(vnode, dp, ARG_VNODE2); if ((cnp->cn_flags & LOCKLEAF) == 0) VOP_UNLOCK(dp, 0); success: /* * Because of lookup_shared we may have the vnode shared locked, but * the caller may want it to be exclusively locked. */ if (needs_exclusive_leaf(dp->v_mount, cnp->cn_flags) && VOP_ISLOCKED(dp) != LK_EXCLUSIVE) { vn_lock(dp, LK_UPGRADE | LK_RETRY); if (dp->v_iflag & VI_DOOMED) { error = ENOENT; goto bad2; } } if (vfslocked && dvfslocked) VFS_UNLOCK_GIANT(dvfslocked); /* Only need one */ if (vfslocked || dvfslocked) ndp->ni_cnd.cn_flags |= GIANTHELD; return (0); bad2: if (dp != ndp->ni_dvp) vput(ndp->ni_dvp); else vrele(ndp->ni_dvp); bad: if (!dpunlocked) vput(dp); VFS_UNLOCK_GIANT(vfslocked); VFS_UNLOCK_GIANT(dvfslocked); ndp->ni_cnd.cn_flags &= ~GIANTHELD; ndp->ni_vp = NULL; return (error); } /* * relookup - lookup a path name component * Used by lookup to re-acquire things. */ int relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) { struct vnode *dp = 0; /* the directory we are searching */ int wantparent; /* 1 => wantparent or lockparent flag */ int rdonly; /* lookup read-only flag bit */ int error = 0; KASSERT(cnp->cn_flags & ISLASTCN, ("relookup: Not given last component.")); /* * Setup: break out flag bits into variables. */ wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT); KASSERT(wantparent, ("relookup: parent not wanted.")); rdonly = cnp->cn_flags & RDONLY; cnp->cn_flags &= ~ISSYMLINK; dp = dvp; cnp->cn_lkflags = LK_EXCLUSIVE; vn_lock(dp, LK_EXCLUSIVE | LK_RETRY); /* * Search a new directory. * * 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 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 (cnp->cn_nameiop != LOOKUP || wantparent) { error = EISDIR; goto bad; } if (dp->v_type != VDIR) { error = ENOTDIR; goto bad; } if (!(cnp->cn_flags & LOCKLEAF)) VOP_UNLOCK(dp, 0); *vpp = dp; /* XXX This should probably move to the top of function. */ 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. */ #ifdef NAMEI_DIAGNOSTIC vprint("search in:", dp); #endif if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) { KASSERT(*vpp == NULL, ("leaf should be empty")); if (error != EJUSTRETURN) goto bad; /* * If creating and at end of pathname, then can consider * allowing file to be created. */ if (rdonly) { error = EROFS; goto bad; } /* ASSERT(dvp == ndp->ni_startdir) */ if (cnp->cn_flags & SAVESTART) VREF(dvp); if ((cnp->cn_flags & LOCKPARENT) == 0) VOP_UNLOCK(dp, 0); /* * This is a temporary assert to make sure I know what the * behavior here was. */ KASSERT((cnp->cn_flags & (WANTPARENT|LOCKPARENT)) != 0, ("relookup: Unhandled case.")); /* * 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. */ return (0); } dp = *vpp; /* * Disallow directory write attempts on read-only filesystems. */ if (rdonly && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { if (dvp == dp) vrele(dvp); else vput(dvp); error = EROFS; goto bad; } /* * Set the parent lock/ref state to the requested state. */ if ((cnp->cn_flags & LOCKPARENT) == 0 && dvp != dp) { if (wantparent) VOP_UNLOCK(dvp, 0); else vput(dvp); } else if (!wantparent) vrele(dvp); /* * Check for symbolic link */ KASSERT(dp->v_type != VLNK || !(cnp->cn_flags & FOLLOW), ("relookup: symlink found.\n")); /* ASSERT(dvp == ndp->ni_startdir) */ if (cnp->cn_flags & SAVESTART) VREF(dvp); if ((cnp->cn_flags & LOCKLEAF) == 0) VOP_UNLOCK(dp, 0); return (0); bad: vput(dp); *vpp = NULL; return (error); } /* * Free data allocated by namei(); see namei(9) for details. */ void NDFREE(struct nameidata *ndp, const u_int flags) { int unlock_dvp; int unlock_vp; unlock_dvp = 0; unlock_vp = 0; if (!(flags & NDF_NO_FREE_PNBUF) && (ndp->ni_cnd.cn_flags & HASBUF)) { uma_zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); ndp->ni_cnd.cn_flags &= ~HASBUF; } if (!(flags & NDF_NO_VP_UNLOCK) && (ndp->ni_cnd.cn_flags & LOCKLEAF) && ndp->ni_vp) unlock_vp = 1; if (!(flags & NDF_NO_VP_RELE) && ndp->ni_vp) { if (unlock_vp) { vput(ndp->ni_vp); unlock_vp = 0; } else vrele(ndp->ni_vp); ndp->ni_vp = NULL; } if (unlock_vp) VOP_UNLOCK(ndp->ni_vp, 0); if (!(flags & NDF_NO_DVP_UNLOCK) && (ndp->ni_cnd.cn_flags & LOCKPARENT) && ndp->ni_dvp != ndp->ni_vp) unlock_dvp = 1; if (!(flags & NDF_NO_DVP_RELE) && (ndp->ni_cnd.cn_flags & (LOCKPARENT|WANTPARENT))) { if (unlock_dvp) { vput(ndp->ni_dvp); unlock_dvp = 0; } else vrele(ndp->ni_dvp); ndp->ni_dvp = NULL; } if (unlock_dvp) VOP_UNLOCK(ndp->ni_dvp, 0); if (!(flags & NDF_NO_STARTDIR_RELE) && (ndp->ni_cnd.cn_flags & SAVESTART)) { vrele(ndp->ni_startdir); ndp->ni_startdir = NULL; } } /* * Determine if there is a suitable alternate filename under the specified * prefix for the specified path. If the create flag is set, then the * alternate prefix will be used so long as the parent directory exists. * This is used by the various compatiblity ABIs so that Linux binaries prefer * files under /compat/linux for example. The chosen path (whether under * the prefix or under /) is returned in a kernel malloc'd buffer pointed * to by pathbuf. The caller is responsible for free'ing the buffer from * the M_TEMP bucket if one is returned. */ int kern_alternate_path(struct thread *td, const char *prefix, const char *path, enum uio_seg pathseg, char **pathbuf, int create, int dirfd) { struct nameidata nd, ndroot; char *ptr, *buf, *cp; size_t len, sz; int error; buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); *pathbuf = buf; /* Copy the prefix into the new pathname as a starting point. */ len = strlcpy(buf, prefix, MAXPATHLEN); if (len >= MAXPATHLEN) { *pathbuf = NULL; free(buf, M_TEMP); return (EINVAL); } sz = MAXPATHLEN - len; ptr = buf + len; /* Append the filename to the prefix. */ if (pathseg == UIO_SYSSPACE) error = copystr(path, ptr, sz, &len); else error = copyinstr(path, ptr, sz, &len); if (error) { *pathbuf = NULL; free(buf, M_TEMP); return (error); } /* Only use a prefix with absolute pathnames. */ if (*ptr != '/') { error = EINVAL; goto keeporig; } if (dirfd != AT_FDCWD) { /* * We want the original because the "prefix" is * included in the already opened dirfd. */ bcopy(ptr, buf, len); return (0); } /* * We know that there is a / somewhere in this pathname. * Search backwards for it, to find the file's parent dir * to see if it exists in the alternate tree. If it does, * and we want to create a file (cflag is set). We don't * need to worry about the root comparison in this case. */ if (create) { for (cp = &ptr[len] - 1; *cp != '/'; cp--); *cp = '\0'; NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); error = namei(&nd); *cp = '/'; if (error != 0) goto keeporig; } else { NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, buf, td); error = namei(&nd); if (error != 0) goto keeporig; /* * We now compare the vnode of the prefix to the one * vnode asked. If they resolve to be the same, then we * ignore the match so that the real root gets used. * This avoids the problem of traversing "../.." to find the * root directory and never finding it, because "/" resolves * to the emulation root directory. This is expensive :-( */ NDINIT(&ndroot, LOOKUP, FOLLOW | MPSAFE, UIO_SYSSPACE, prefix, td); /* We shouldn't ever get an error from this namei(). */ error = namei(&ndroot); if (error == 0) { if (nd.ni_vp == ndroot.ni_vp) error = ENOENT; NDFREE(&ndroot, NDF_ONLY_PNBUF); vrele(ndroot.ni_vp); VFS_UNLOCK_GIANT(NDHASGIANT(&ndroot)); } } NDFREE(&nd, NDF_ONLY_PNBUF); vrele(nd.ni_vp); VFS_UNLOCK_GIANT(NDHASGIANT(&nd)); keeporig: /* If there was an error, use the original path name. */ if (error) bcopy(ptr, buf, len); return (error); }