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11178ee4c1
freebsd/sys/kern/vfs_lookup.c
Jeff Roberson 2f0bca553a - Don't check v_mount for NULL to determine if a vnode has been recycled. 
Use the more appropriate VI_DOOMED flag instead.

Sponsored by:	Isilon Systems, Inc.
MFC After:	1 week
2006-02-06 10:15:27 +00:00

1066 lines
29 KiB
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/*-
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ktrace.h"
#include "opt_mac.h"
#include "opt_vfs.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mac.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/filedesc.h>
#include <sys/proc.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.h>
#include <vm/uma.h>
#define NAMEI_DIAGNOSTIC 1
#undef NAMEI_DIAGNOSTIC
/*
* Allocation zone for namei
*/
uma_zone_t namei_zone;
static void
nameiinit(void *dummy __unused)
{
namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL)
#ifdef LOOKUP_SHARED
static int lookup_shared = 1;
#else
static int lookup_shared = 0;
#endif
SYSCTL_INT(_vfs, OID_AUTO, lookup_shared, CTLFLAG_RW, &lookup_shared, 0,
"Enables/Disables shared locks for path name translation");
/*
* 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;
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_LOCK(fdp);
ndp->ni_rootdir = fdp->fd_rdir;
ndp->ni_topdir = fdp->fd_jdir;
dp = fdp->fd_cdir;
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
VREF(dp);
FILEDESC_UNLOCK(fdp);
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_check_vnode_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);
}
/*
* 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 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;
int tvfslocked;
int dvfslocked;
/*
* Setup: break out flag bits into variables.
*/
vfslocked = (ndp->ni_cnd.cn_flags & GIANTHELD) != 0;
dvfslocked = 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, cnp->cn_lkflags | LK_RETRY, td);
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, td);
/* 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) {
ndp->ni_dvp = dp;
ndp->ni_vp = dp;
VREF(dp);
goto nextname;
}
if ((dp->v_vflag & VV_ROOT) == 0 ||
(cnp->cn_flags & NOCROSSMOUNT))
break;
if (dp->v_iflag & VI_DOOMED) { /* forced unmount */
error = EBADF;
goto bad;
}
tdp = dp;
dp = dp->v_mount->mnt_vnodecovered;
tvfslocked = vfslocked;
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
VREF(dp);
vput(tdp);
VFS_UNLOCK_GIANT(tvfslocked);
vn_lock(dp, cnp->cn_lkflags | LK_RETRY, td);
}
}
/*
* 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_check_vnode_lookup(td->td_ucred, dp, cnp);
if (error)
goto bad;
}
#endif
ndp->ni_dvp = dp;
ndp->ni_vp = NULL;
ASSERT_VOP_LOCKED(dp, "lookup");
/*
* If we have a shared lock we may need to upgrade the lock for the
* last operation.
*/
if (VOP_ISLOCKED(dp, td) == LK_SHARED &&
(cnp->cn_flags & ISLASTCN) && (cnp->cn_flags & LOCKPARENT))
vn_lock(dp, LK_UPGRADE|LK_RETRY, td);
/*
* If we're looking up the last component and we need an exclusive
* lock, adjust our lkflags.
*/
if ((cnp->cn_flags & (ISLASTCN|LOCKSHARED|LOCKLEAF)) ==
(ISLASTCN|LOCKLEAF))
cnp->cn_lkflags = LK_EXCLUSIVE;
#ifdef NAMEI_DIAGNOSTIC
vprint("lookup in", dp);
#endif
if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
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 = vfslocked;
vfslocked = VFS_LOCK_GIANT(dp->v_mount);
VREF(dp);
vput(tdp);
VFS_UNLOCK_GIANT(tvfslocked);
vn_lock(dp, cnp->cn_lkflags | LK_RETRY, td);
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, td);
/*
* 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 inode in ndp->ni_dvp.
*/
if (cnp->cn_flags & SAVESTART) {
ndp->ni_startdir = ndp->ni_dvp;
VREF(ndp->ni_startdir);
}
goto success;
}
#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 filesystem.
*/
while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
(cnp->cn_flags & NOCROSSMOUNT) == 0) {
KASSERT(dp != ndp->ni_dvp, ("XXX"));
if (vfs_busy(mp, 0, 0, td))
continue;
vput(dp);
dvfslocked = vfslocked;
vfslocked = VFS_LOCK_GIANT(mp);
VOP_UNLOCK(ndp->ni_dvp, 0, td);
error = VFS_ROOT(mp, cnp->cn_lkflags, &tdp, td);
VOP_LOCK(ndp->ni_dvp, cnp->cn_lkflags | LK_RETRY, td);
vfs_unbusy(mp, td);
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 = EBADF;
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, td);
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 = 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, td);
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, td);
success:
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-aquire things.
*/
int
relookup(dvp, vpp, cnp)
struct vnode *dvp, **vpp;
struct componentname *cnp;
{
struct thread *td = cnp->cn_thread;
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, td);
/*
* 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, td);
*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, td);
/*
* 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 inode 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, td);
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, td);
return (0);
bad:
vput(dp);
*vpp = NULL;
return (error);
}
/*
* Free data allocated by namei(); see namei(9) for details.
*/
void
NDFREE(ndp, flags)
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, ndp->ni_cnd.cn_thread);
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, ndp->ni_cnd.cn_thread);
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, char *path,
enum uio_seg pathseg, char **pathbuf, int create)
{
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;
}
/*
* 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);
}
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