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vfs_lookup.c
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vfs_lookup.c
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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
*/
#include <sys/cdefs.h>
#include "opt_capsicum.h"
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dirent.h>
#include <sys/kernel.h>
#include <sys/capsicum.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/lock.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/sdt.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#ifdef INVARIANTS
#include <machine/_inttypes.h>
#endif
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
#include <vm/uma.h>
#ifdef INVARIANTS
static void NDVALIDATE_impl(struct nameidata *, int);
#define NDVALIDATE(ndp) NDVALIDATE_impl(ndp, __LINE__)
#else
#define NDVALIDATE(ndp)
#endif
/*
* Prepare namei() to restart. Reset components to its original state and set
* ISRESTARTED flag which signals the underlying lookup code to change the root
* from ABI root to actual root and prevents a further restarts.
*/
#define NDRESTART(ndp) do { \
NDREINIT_DBG(ndp); \
ndp->ni_resflags = 0; \
ndp->ni_cnd.cn_flags &= ~NAMEI_INTERNAL_FLAGS; \
ndp->ni_cnd.cn_flags |= ISRESTARTED; \
} while (0)
#ifdef KTRACE
#define NIKTRCAPFAIL(path) ktrcapfail(CAPFAIL_NAMEI, (path))
#else
#define NIKTRCAPFAIL(path)
#endif
#define NI_CAP_VIOLATION(ndp, path) do { \
NIKTRCAPFAIL(path); \
(ndp)->ni_lcf &= ~NI_LCF_KTR_FLAGS; \
} while (0)
SDT_PROVIDER_DEFINE(vfs);
SDT_PROBE_DEFINE4(vfs, namei, lookup, entry, "struct vnode *", "char *",
"unsigned long", "bool");
SDT_PROBE_DEFINE4(vfs, namei, lookup, return, "int", "struct vnode *", "bool",
"struct nameidata");
/* Allocation zone for namei. */
uma_zone_t namei_zone;
/* Placeholder vnode for mp traversal. */
static struct vnode *vp_crossmp;
static int
crossmp_vop_islocked(struct vop_islocked_args *ap)
{
return (LK_SHARED);
}
static int
crossmp_vop_lock1(struct vop_lock1_args *ap)
{
struct vnode *vp;
struct lock *lk __diagused;
int flags;
vp = ap->a_vp;
lk = vp->v_vnlock;
flags = ap->a_flags;
KASSERT((flags & (LK_SHARED | LK_NOWAIT)) == (LK_SHARED | LK_NOWAIT),
("%s: invalid lock request 0x%x for crossmp", __func__, flags));
if ((flags & LK_INTERLOCK) != 0)
VI_UNLOCK(vp);
LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, ap->a_file, ap->a_line);
return (0);
}
static int
crossmp_vop_unlock(struct vop_unlock_args *ap)
{
struct vnode *vp;
struct lock *lk __diagused;
vp = ap->a_vp;
lk = vp->v_vnlock;
LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, LOCK_FILE,
LOCK_LINE);
return (0);
}
static struct vop_vector crossmp_vnodeops = {
.vop_default = &default_vnodeops,
.vop_islocked = crossmp_vop_islocked,
.vop_lock1 = crossmp_vop_lock1,
.vop_unlock = crossmp_vop_unlock,
};
/*
* VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode
* gets allocated early. See nameiinit for the direct call below.
*/
struct nameicap_tracker {
struct vnode *dp;
TAILQ_ENTRY(nameicap_tracker) nm_link;
};
/* Zone for cap mode tracker elements used for dotdot capability checks. */
MALLOC_DEFINE(M_NAMEITRACKER, "namei_tracker", "namei tracking for dotdot");
static void
nameiinit(void *dummy __unused)
{
namei_zone = uma_zcreate("NAMEI", MAXPATHLEN, NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
vfs_vector_op_register(&crossmp_vnodeops);
getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
vp_crossmp->v_state = VSTATE_CONSTRUCTED;
vp_crossmp->v_irflag |= VIRF_CROSSMP;
}
SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
static int lookup_cap_dotdot = 1;
SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot, CTLFLAG_RWTUN,
&lookup_cap_dotdot, 0,
"enables \"..\" components in path lookup in capability mode");
static int lookup_cap_dotdot_nonlocal = 1;
SYSCTL_INT(_vfs, OID_AUTO, lookup_cap_dotdot_nonlocal, CTLFLAG_RWTUN,
&lookup_cap_dotdot_nonlocal, 0,
"enables \"..\" components in path lookup in capability mode "
"on non-local mount");
static void
nameicap_tracker_add(struct nameidata *ndp, struct vnode *dp)
{
struct nameicap_tracker *nt;
if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0 || dp->v_type != VDIR)
return;
nt = TAILQ_LAST(&ndp->ni_cap_tracker, nameicap_tracker_head);
if (nt != NULL && nt->dp == dp)
return;
nt = malloc(sizeof(*nt), M_NAMEITRACKER, M_WAITOK);
vhold(dp);
nt->dp = dp;
TAILQ_INSERT_TAIL(&ndp->ni_cap_tracker, nt, nm_link);
}
static void
nameicap_cleanup_from(struct nameidata *ndp, struct nameicap_tracker *first)
{
struct nameicap_tracker *nt, *nt1;
nt = first;
TAILQ_FOREACH_FROM_SAFE(nt, &ndp->ni_cap_tracker, nm_link, nt1) {
TAILQ_REMOVE(&ndp->ni_cap_tracker, nt, nm_link);
vdrop(nt->dp);
free(nt, M_NAMEITRACKER);
}
}
static void
nameicap_cleanup(struct nameidata *ndp)
{
KASSERT(TAILQ_EMPTY(&ndp->ni_cap_tracker) ||
(ndp->ni_lcf & NI_LCF_CAP_DOTDOT) != 0, ("not strictrelative"));
nameicap_cleanup_from(ndp, NULL);
}
/*
* For dotdot lookups in capability mode, only allow the component
* lookup to succeed if the resulting directory was already traversed
* during the operation. This catches situations where already
* traversed directory is moved to different parent, and then we walk
* over it with dotdots.
*
* Also allow to force failure of dotdot lookups for non-local
* filesystems, where external agents might assist local lookups to
* escape the compartment.
*/
static int
nameicap_check_dotdot(struct nameidata *ndp, struct vnode *dp)
{
struct nameicap_tracker *nt;
struct mount *mp;
if (dp == NULL || dp->v_type != VDIR || (ndp->ni_lcf &
NI_LCF_STRICTREL) == 0)
return (0);
if (__predict_false((ndp->ni_lcf & (NI_LCF_STRICTREL_KTR |
NI_LCF_CAP_DOTDOT_KTR)) == NI_LCF_STRICTREL_KTR))
NI_CAP_VIOLATION(ndp, ndp->ni_cnd.cn_pnbuf);
if ((ndp->ni_lcf & NI_LCF_CAP_DOTDOT) == 0)
return (ENOTCAPABLE);
mp = dp->v_mount;
if (lookup_cap_dotdot_nonlocal == 0 && mp != NULL &&
(mp->mnt_flag & MNT_LOCAL) == 0)
goto capfail;
TAILQ_FOREACH_REVERSE(nt, &ndp->ni_cap_tracker, nameicap_tracker_head,
nm_link) {
if (dp == nt->dp) {
nt = TAILQ_NEXT(nt, nm_link);
if (nt != NULL)
nameicap_cleanup_from(ndp, nt);
return (0);
}
}
capfail:
if (__predict_false((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0))
NI_CAP_VIOLATION(ndp, ndp->ni_cnd.cn_pnbuf);
return (ENOTCAPABLE);
}
static void
namei_cleanup_cnp(struct componentname *cnp)
{
uma_zfree(namei_zone, cnp->cn_pnbuf);
cnp->cn_pnbuf = NULL;
cnp->cn_nameptr = NULL;
}
static int
namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
{
struct componentname *cnp;
cnp = &ndp->ni_cnd;
if (__predict_false((ndp->ni_lcf & (NI_LCF_STRICTREL |
NI_LCF_STRICTREL_KTR)) != 0)) {
if ((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0)
NI_CAP_VIOLATION(ndp, cnp->cn_pnbuf);
if ((ndp->ni_lcf & NI_LCF_STRICTREL) != 0)
return (ENOTCAPABLE);
}
while (*(cnp->cn_nameptr) == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
*dpp = ndp->ni_rootdir;
vrefact(*dpp);
return (0);
}
static int
namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp)
{
struct componentname *cnp;
struct thread *td;
struct pwd *pwd;
int error;
bool startdir_used;
cnp = &ndp->ni_cnd;
td = curthread;
startdir_used = false;
*pwdp = NULL;
*dpp = NULL;
#ifdef CAPABILITY_MODE
/*
* In capability mode, lookups must be restricted to happen in
* the subtree with the root specified by the file descriptor:
* - The root must be real file descriptor, not the pseudo-descriptor
* AT_FDCWD.
* - The passed path must be relative and not absolute.
* - If lookup_cap_dotdot is disabled, path must not contain the
* '..' components.
* - If lookup_cap_dotdot is enabled, we verify that all '..'
* components lookups result in the directories which were
* previously walked by us, which prevents an escape from
* the relative root.
*/
if ((cnp->cn_flags & NOCAPCHECK) == 0) {
if (CAP_TRACING(td)) {
ndp->ni_lcf |= NI_LCF_STRICTREL_KTR;
if (ndp->ni_dirfd == AT_FDCWD)
NI_CAP_VIOLATION(ndp, "AT_FDCWD");
}
if (IN_CAPABILITY_MODE(td)) {
ndp->ni_lcf |= NI_LCF_STRICTREL;
ndp->ni_resflags |= NIRES_STRICTREL;
if (ndp->ni_dirfd == AT_FDCWD)
return (ECAPMODE);
}
}
#endif
error = 0;
/*
* Get starting point for the translation.
*/
pwd = pwd_hold(td);
/*
* The reference on ni_rootdir is acquired in the block below to avoid
* back-to-back atomics for absolute lookups.
*/
namei_setup_rootdir(ndp, cnp, pwd);
ndp->ni_topdir = pwd->pwd_jdir;
if (cnp->cn_pnbuf[0] == '/') {
ndp->ni_resflags |= NIRES_ABS;
error = namei_handle_root(ndp, dpp);
} else {
if (ndp->ni_startdir != NULL) {
*dpp = ndp->ni_startdir;
startdir_used = true;
} else if (ndp->ni_dirfd == AT_FDCWD) {
*dpp = pwd->pwd_cdir;
vrefact(*dpp);
} else {
if (cnp->cn_flags & AUDITVNODE1)
AUDIT_ARG_ATFD1(ndp->ni_dirfd);
if (cnp->cn_flags & AUDITVNODE2)
AUDIT_ARG_ATFD2(ndp->ni_dirfd);
error = fgetvp_lookup(ndp, dpp);
}
if (error == 0 && (*dpp)->v_type != VDIR &&
(cnp->cn_pnbuf[0] != '\0' ||
(cnp->cn_flags & EMPTYPATH) == 0))
error = ENOTDIR;
}
if (error == 0 && (cnp->cn_flags & RBENEATH) != 0) {
if (cnp->cn_pnbuf[0] == '/') {
error = ENOTCAPABLE;
} else if ((ndp->ni_lcf & NI_LCF_STRICTREL) == 0) {
ndp->ni_lcf |= NI_LCF_STRICTREL |
NI_LCF_CAP_DOTDOT;
}
}
/*
* If we are auditing the kernel pathname, save the user pathname.
*/
if (AUDITING_TD(td)) {
if (cnp->cn_flags & AUDITVNODE1)
AUDIT_ARG_UPATH1_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
if (cnp->cn_flags & AUDITVNODE2)
AUDIT_ARG_UPATH2_VP(td, ndp->ni_rootdir, *dpp, cnp->cn_pnbuf);
}
if (ndp->ni_startdir != NULL && !startdir_used)
vrele(ndp->ni_startdir);
if (error != 0) {
if (*dpp != NULL)
vrele(*dpp);
pwd_drop(pwd);
return (error);
}
if (lookup_cap_dotdot != 0) {
if ((ndp->ni_lcf & NI_LCF_STRICTREL_KTR) != 0)
ndp->ni_lcf |= NI_LCF_CAP_DOTDOT_KTR;
if ((ndp->ni_lcf & NI_LCF_STRICTREL) != 0)
ndp->ni_lcf |= NI_LCF_CAP_DOTDOT;
}
SDT_PROBE4(vfs, namei, lookup, entry, *dpp, cnp->cn_pnbuf,
cnp->cn_flags, false);
*pwdp = pwd;
return (0);
}
static int
namei_getpath(struct nameidata *ndp)
{
struct componentname *cnp;
int error;
cnp = &ndp->ni_cnd;
/*
* Get a buffer for the name to be translated, and copy the
* name into the buffer.
*/
cnp->cn_pnbuf = uma_zalloc(namei_zone, 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);
}
return (error);
}
static int
namei_emptypath(struct nameidata *ndp)
{
struct componentname *cnp;
struct pwd *pwd;
struct vnode *dp;
int error;
cnp = &ndp->ni_cnd;
MPASS(*cnp->cn_pnbuf == '\0');
MPASS((cnp->cn_flags & EMPTYPATH) != 0);
MPASS((cnp->cn_flags & (LOCKPARENT | WANTPARENT)) == 0);
ndp->ni_resflags |= NIRES_EMPTYPATH;
error = namei_setup(ndp, &dp, &pwd);
if (error != 0) {
goto errout;
}
/*
* Usecount on dp already provided by namei_setup.
*/
ndp->ni_vp = dp;
pwd_drop(pwd);
NDVALIDATE(ndp);
if ((cnp->cn_flags & LOCKLEAF) != 0) {
VOP_LOCK(dp, (cnp->cn_flags & LOCKSHARED) != 0 ?
LK_SHARED : LK_EXCLUSIVE);
if (VN_IS_DOOMED(dp)) {
vput(dp);
error = ENOENT;
goto errout;
}
}
SDT_PROBE4(vfs, namei, lookup, return, 0, ndp->ni_vp, false, ndp);
return (0);
errout:
SDT_PROBE4(vfs, namei, lookup, return, error, NULL, false, ndp);
namei_cleanup_cnp(cnp);
return (error);
}
static int __noinline
namei_follow_link(struct nameidata *ndp)
{
char *cp;
struct iovec aiov;
struct uio auio;
struct componentname *cnp;
struct thread *td;
int error, linklen;
error = 0;
cnp = &ndp->ni_cnd;
td = curthread;
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
error = ELOOP;
goto out;
}
#ifdef MAC
if ((cnp->cn_flags & NOMACCHECK) == 0) {
error = mac_vnode_check_readlink(td->td_ucred, ndp->ni_vp);
if (error != 0)
goto out;
}
#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 = td;
auio.uio_resid = MAXPATHLEN;
error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
if (error != 0) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
goto out;
}
linklen = MAXPATHLEN - auio.uio_resid;
if (linklen == 0) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
error = ENOENT;
goto out;
}
if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
error = ENAMETOOLONG;
goto out;
}
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;
out:
return (error);
}
/*
* 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 vnode *dp; /* the directory we are searching */
struct componentname *cnp;
struct thread *td;
struct pwd *pwd;
int error;
enum cache_fpl_status status;
cnp = &ndp->ni_cnd;
td = curthread;
#ifdef INVARIANTS
KASSERT((ndp->ni_debugflags & NAMEI_DBG_CALLED) == 0,
("%s: repeated call to namei without NDREINIT", __func__));
KASSERT(ndp->ni_debugflags == NAMEI_DBG_INITED,
("%s: bad debugflags %d", __func__, ndp->ni_debugflags));
ndp->ni_debugflags |= NAMEI_DBG_CALLED;
if (ndp->ni_startdir != NULL)
ndp->ni_debugflags |= NAMEI_DBG_HADSTARTDIR;
if (cnp->cn_flags & FAILIFEXISTS) {
KASSERT(cnp->cn_nameiop == CREATE,
("%s: FAILIFEXISTS passed for op %d", __func__, cnp->cn_nameiop));
/*
* The limitation below is to restrict hairy corner cases.
*/
KASSERT((cnp->cn_flags & (LOCKPARENT | LOCKLEAF)) == LOCKPARENT,
("%s: FAILIFEXISTS must be passed with LOCKPARENT and without LOCKLEAF",
__func__));
}
#endif
ndp->ni_cnd.cn_cred = td->td_ucred;
KASSERT(ndp->ni_resflags == 0, ("%s: garbage in ni_resflags: %x\n",
__func__, ndp->ni_resflags));
KASSERT(cnp->cn_cred && td->td_proc, ("namei: bad cred/proc"));
KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0,
("namei: unexpected flags: %" PRIx64 "\n",
cnp->cn_flags & NAMEI_INTERNAL_FLAGS));
if (cnp->cn_flags & NOCACHE)
KASSERT(cnp->cn_nameiop != LOOKUP,
("%s: NOCACHE passed with LOOKUP", __func__));
MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
ndp->ni_startdir->v_type == VBAD);
restart:
ndp->ni_lcf = 0;
ndp->ni_loopcnt = 0;
ndp->ni_vp = NULL;
error = namei_getpath(ndp);
if (__predict_false(error != 0)) {
namei_cleanup_cnp(cnp);
SDT_PROBE4(vfs, namei, lookup, return, error, NULL,
false, ndp);
return (error);
}
cnp->cn_nameptr = cnp->cn_pnbuf;
#ifdef KTRACE
if (KTRPOINT(td, KTR_NAMEI)) {
ktrnamei(cnp->cn_pnbuf);
}
#endif
TSNAMEI(curthread->td_proc->p_pid, cnp->cn_pnbuf);
/*
* First try looking up the target without locking any vnodes.
*
* We may need to start from scratch or pick up where it left off.
*/
error = cache_fplookup(ndp, &status, &pwd);
switch (status) {
case CACHE_FPL_STATUS_UNSET:
__assert_unreachable();
break;
case CACHE_FPL_STATUS_HANDLED:
if (error == 0)
NDVALIDATE(ndp);
else if (__predict_false(pwd->pwd_adir != pwd->pwd_rdir &&
(cnp->cn_flags & ISRESTARTED) == 0)) {
namei_cleanup_cnp(cnp);
NDRESTART(ndp);
goto restart;
}
return (error);
case CACHE_FPL_STATUS_PARTIAL:
TAILQ_INIT(&ndp->ni_cap_tracker);
dp = ndp->ni_startdir;
break;
case CACHE_FPL_STATUS_DESTROYED:
ndp->ni_loopcnt = 0;
error = namei_getpath(ndp);
if (__predict_false(error != 0)) {
namei_cleanup_cnp(cnp);
return (error);
}
cnp->cn_nameptr = cnp->cn_pnbuf;
/* FALLTHROUGH */
case CACHE_FPL_STATUS_ABORTED:
TAILQ_INIT(&ndp->ni_cap_tracker);
MPASS(ndp->ni_lcf == 0);
if (*cnp->cn_pnbuf == '\0') {
if ((cnp->cn_flags & EMPTYPATH) != 0) {
return (namei_emptypath(ndp));
}
namei_cleanup_cnp(cnp);
SDT_PROBE4(vfs, namei, lookup, return, ENOENT, NULL,
false, ndp);
return (ENOENT);
}
error = namei_setup(ndp, &dp, &pwd);
if (error != 0) {
namei_cleanup_cnp(cnp);
return (error);
}
break;
}
/*
* Locked lookup.
*/
for (;;) {
ndp->ni_startdir = dp;
error = vfs_lookup(ndp);
if (error != 0) {
if (__predict_false(pwd->pwd_adir != pwd->pwd_rdir &&
error == ENOENT &&
(cnp->cn_flags & ISRESTARTED) == 0)) {
nameicap_cleanup(ndp);
pwd_drop(pwd);
namei_cleanup_cnp(cnp);
NDRESTART(ndp);
goto restart;
} else
goto out;
}
/*
* If not a symbolic link, we're done.
*/
if ((cnp->cn_flags & ISSYMLINK) == 0) {
SDT_PROBE4(vfs, namei, lookup, return, error,
ndp->ni_vp, false, ndp);
nameicap_cleanup(ndp);
pwd_drop(pwd);
NDVALIDATE(ndp);
return (0);
}
error = namei_follow_link(ndp);
if (error != 0)
break;
vput(ndp->ni_vp);
dp = ndp->ni_dvp;
/*
* Check if root directory should replace current directory.
*/
cnp->cn_nameptr = cnp->cn_pnbuf;
if (*(cnp->cn_nameptr) == '/') {
/*
* Reset the lookup to start from the real root without
* origin path name reloading.
*/
if (__predict_false(ndp->ni_rootdir != pwd->pwd_rdir)) {
cnp->cn_flags |= ISRESTARTED;
ndp->ni_rootdir = pwd->pwd_rdir;
}
vrele(dp);
error = namei_handle_root(ndp, &dp);
if (error != 0)
goto out;
}
}
vput(ndp->ni_vp);
ndp->ni_vp = NULL;
vrele(ndp->ni_dvp);
out:
MPASS(error != 0);
SDT_PROBE4(vfs, namei, lookup, return, error, NULL, false, ndp);
namei_cleanup_cnp(cnp);
nameicap_cleanup(ndp);
pwd_drop(pwd);
return (error);
}
static int
enforce_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;
}
lkflags |= LK_NODDLKTREAT;
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) != 0)
return (!MNT_EXTENDED_SHARED(mp));
/*
* Lookup requests outside of open() that specify LOCKSHARED
* only need a shared lock on the leaf vnode.
*/
return (0);
}
/*
* Various filesystems expect to be able to copy a name component with length
* bounded by NAME_MAX into a directory entry buffer of size MAXNAMLEN. Make
* sure that these are the same size.
*/
_Static_assert(MAXNAMLEN == NAME_MAX,
"MAXNAMLEN and NAME_MAX have different values");
static int __noinline
vfs_lookup_degenerate(struct nameidata *ndp, struct vnode *dp, int wantparent)
{
struct componentname *cnp;
struct mount *mp;
int error;
cnp = &ndp->ni_cnd;
cnp->cn_flags |= ISLASTCN;
mp = atomic_load_ptr(&dp->v_mount);
if (needs_exclusive_leaf(mp, cnp->cn_flags)) {
cnp->cn_lkflags &= ~LK_SHARED;
cnp->cn_lkflags |= LK_EXCLUSIVE;
}
vn_lock(dp, enforce_lkflags(mp, cnp->cn_lkflags | LK_RETRY));
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;
cnp->cn_namelen = 0;
if (cnp->cn_flags & AUDITVNODE1)
AUDIT_ARG_VNODE1(dp);
else if (cnp->cn_flags & AUDITVNODE2)
AUDIT_ARG_VNODE2(dp);
if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
VOP_UNLOCK(dp);
return (0);
bad:
VOP_UNLOCK(dp);
return (error);
}
/*
* FAILIFEXISTS handling.
*
* XXX namei called with LOCKPARENT but not LOCKLEAF has the strange
* behaviour of leaving the vnode unlocked if the target is the same
* vnode as the parent.
*/
static int __noinline
vfs_lookup_failifexists(struct nameidata *ndp)
{
struct componentname *cnp __diagused;
cnp = &ndp->ni_cnd;
MPASS((cnp->cn_flags & ISSYMLINK) == 0);
if (ndp->ni_vp == ndp->ni_dvp)
vrele(ndp->ni_dvp);
else
vput(ndp->ni_dvp);
vrele(ndp->ni_vp);
ndp->ni_dvp = NULL;
ndp->ni_vp = NULL;
NDFREE_PNBUF(ndp);
return (EEXIST);
}
static int __noinline
vfs_lookup_cross_mount(struct nameidata *ndp)
{
struct componentname *cnp;
struct mount *mp;
struct vnode *dp, *tdp;
int error, crosslkflags;
bool crosslock;
cnp = &ndp->ni_cnd;
dp = ndp->ni_vp;
/*
* The vnode has been mounted on, find the root of the mounted
* filesystem.
*/
do {
mp = dp->v_mountedhere;
ASSERT_VOP_LOCKED(dp, __func__);
VNPASS((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0 && mp != NULL, dp);
crosslock = (dp->v_vflag & VV_CROSSLOCK) != 0;
crosslkflags = enforce_lkflags(mp, cnp->cn_lkflags);
if (__predict_false(crosslock)) {
/*
* We are going to be holding the vnode lock, which
* in this case is shared by the root vnode of the
* filesystem mounted at mp, across the call to
* VFS_ROOT(). Make the situation clear to the
* filesystem by passing LK_CANRECURSE if the
* lock is held exclusive, or by clearinng
* LK_NODDLKTREAT to allow recursion on the shared
* lock in the presence of an exclusive waiter.
*/
if (VOP_ISLOCKED(dp) == LK_EXCLUSIVE) {
crosslkflags &= ~LK_SHARED;
crosslkflags |= LK_EXCLUSIVE | LK_CANRECURSE;
} else if ((crosslkflags & LK_EXCLUSIVE) != 0) {
error = vn_lock(dp, LK_UPGRADE);
if (error != 0) {
MPASS(error == ENOENT);
vrele(dp);
if (dp != ndp->ni_dvp)
vput(ndp->ni_dvp);
else
vrele(ndp->ni_dvp);
break;
}
if (dp->v_mountedhere != mp) {
/*
* Note that we rely on the
* VIRF_MOUNTPOINT loop condition to
* ensure we stop iterating if dp is
* no longer a mountpoint at all.
*/
continue;
}
} else
crosslkflags &= ~LK_NODDLKTREAT;
}
if (vfs_busy(mp, 0) != 0)
continue;
if (__predict_true(!crosslock))
vput(dp);
if (dp != ndp->ni_dvp)
vput(ndp->ni_dvp);
else
vrele(ndp->ni_dvp);
vrefact(vp_crossmp);
ndp->ni_dvp = vp_crossmp;
error = VFS_ROOT(mp, crosslkflags, &tdp);
vfs_unbusy(mp);
if (__predict_false(crosslock))
vput(dp);
if (vn_lock(vp_crossmp, LK_SHARED | LK_NOWAIT))
panic("vp_crossmp exclusively locked or reclaimed");
if (error != 0)
break;
ndp->ni_vp = dp = tdp;
} while ((vn_irflag_read(dp) & VIRF_MOUNTPOINT) != 0);
return (error);
}
/*
* Search a pathname.
* This is a very central and rather complicated routine.
*
* The pathname is pointed to by cn_nameptr 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 cn_flags
* has ISLASTCN or'ed if the path is completed or ISSYMLINK or'ed if a
* symbolic link needing interpretation is encountered.
*
* The cn_nameiop 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 cn_flags has LOCKPARENT or'ed into it, the parent directory is returned
* locked. If it 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 cn_flags
* the target is returned locked, otherwise it is returned unlocked.
*
* Overall outline of lookup:
*
* handle degenerate case where name is null string
*
* dirloop:
* identify next component of name at ndp->ni_cnd.cn_nameptr
* handle .. special cases related to capabilities, chroot, jail