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gems-kernel/source/THIRDPARTY/xnu/bsd/vfs/vfs_lookup.c
Sam Sneed f5727805f2 add darwin/xnu functionality
2024-06-03 11:29:39 -05:00

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/*
* Copyright (c) 2000-2015 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
* 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 8.10 (Berkeley) 5/27/95
*/
/*
* NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
* support for mandatory and extensible security protections. This notice
* is included in support of clause 2.2 (b) of the Apple Public License,
* Version 2.0.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/syslimits.h>
#include <sys/time.h>
#include <sys/namei.h>
#include <sys/vm.h>
#include <sys/vnode_internal.h>
#include <sys/mount_internal.h>
#include <sys/errno.h>
#include <kern/kalloc.h>
#include <sys/filedesc.h>
#include <sys/proc_internal.h>
#include <sys/kdebug.h>
#include <sys/unistd.h> /* For _PC_NAME_MAX */
#include <sys/uio_internal.h>
#include <sys/kauth.h>
#include <kern/zalloc.h>
#include <security/audit/audit.h>
#if CONFIG_MACF
#include <security/mac_framework.h>
#endif
#include <os/atomic_private.h>
#include <sys/paths.h>
#if NAMEDRSRCFORK
#include <sys/xattr.h>
#endif
/*
* The minimum volfs-style pathname is 9.
* Example: "/.vol/1/2"
*/
#define VOLFS_MIN_PATH_LEN 9
#if CONFIG_VOLFS
static int vfs_getrealpath(const char * path, char * realpath, size_t bufsize, vfs_context_t ctx);
#define MAX_VOLFS_RESTARTS 5
#endif
static int lookup_traverse_mountpoints(struct nameidata *ndp, struct componentname *cnp, vnode_t dp, int vbusyflags, vfs_context_t ctx);
static int lookup_handle_symlink(struct nameidata *ndp, vnode_t *new_dp, bool* dp_has_iocount, vfs_context_t ctx);
static int lookup_authorize_search(vnode_t dp, struct componentname *cnp, int dp_authorized_in_cache, vfs_context_t ctx);
static void lookup_consider_update_cache(vnode_t dvp, vnode_t vp, struct componentname *cnp, int nc_generation);
static int lookup_handle_found_vnode(struct nameidata *ndp, struct componentname *cnp, int rdonly,
int vbusyflags, int *keep_going, int nc_generation,
int wantparent, int atroot, vfs_context_t ctx);
static int lookup_handle_emptyname(struct nameidata *ndp, struct componentname *cnp, int wantparent);
#if NAMEDRSRCFORK
static int lookup_handle_rsrc_fork(vnode_t dp, struct nameidata *ndp, struct componentname *cnp, int wantparent, vfs_context_t ctx);
#endif
extern lck_rw_t rootvnode_rw_lock;
/*
* 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
* }
*
* Returns: 0 Success
* ENOENT No such file or directory
* ELOOP Too many levels of symbolic links
* ENAMETOOLONG Filename too long
* copyinstr:EFAULT Bad address
* copyinstr:ENAMETOOLONG Filename too long
* lookup:EBADF Bad file descriptor
* lookup:EROFS
* lookup:EACCES
* lookup:EPERM
* lookup:ERECYCLE vnode was recycled from underneath us in lookup.
* This means we should re-drive lookup from this point.
* lookup: ???
* VNOP_READLINK:???
*/
int
namei(struct nameidata *ndp)
{
struct vnode *dp; /* the directory we are searching */
struct vnode *usedvp = ndp->ni_dvp; /* store pointer to vp in case we must loop due to
* heavy vnode pressure */
uint32_t cnpflags = ndp->ni_cnd.cn_flags; /* store in case we have to restore after loop */
int error;
struct componentname *cnp = &ndp->ni_cnd;
vfs_context_t ctx = cnp->cn_context;
proc_t p = vfs_context_proc(ctx);
#if CONFIG_AUDIT
/* XXX ut should be from context */
uthread_t ut = current_uthread();
#endif
#if CONFIG_VOLFS
int volfs_restarts = 0;
#endif
size_t bytes_copied = 0;
vnode_t rootdir_with_usecount = NULLVP;
vnode_t startdir_with_usecount = NULLVP;
vnode_t usedvp_dp = NULLVP;
int32_t old_count = 0;
bool dp_has_iocount = false;
#if DIAGNOSTIC
if (!vfs_context_ucred(ctx) || !p) {
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
/*
* A compound VNOP found something that needs further processing:
* either a trigger vnode, a covered directory, or a symlink.
*/
if (ndp->ni_flag & NAMEI_CONTLOOKUP) {
int rdonly, vbusyflags, keep_going, wantparent;
rdonly = cnp->cn_flags & RDONLY;
vbusyflags = ((cnp->cn_flags & CN_NBMOUNTLOOK) != 0) ? LK_NOWAIT : 0;
keep_going = 0;
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
ndp->ni_flag &= ~(NAMEI_CONTLOOKUP);
error = lookup_handle_found_vnode(ndp, &ndp->ni_cnd, rdonly, vbusyflags,
&keep_going, ndp->ni_ncgeneration, wantparent, 0, ctx);
if (error) {
goto out_drop;
}
if (keep_going) {
if ((cnp->cn_flags & ISSYMLINK) == 0) {
panic("We need to keep going on a continued lookup, but for vp type %d (tag %d)", ndp->ni_vp->v_type, ndp->ni_vp->v_tag);
}
goto continue_symlink;
}
return 0;
}
vnode_recycled:
/*
* 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 = ndp->ni_pathbuf;
cnp->cn_pnlen = PATHBUFLEN;
}
retry_copy:
if (UIO_SEG_IS_USER_SPACE(ndp->ni_segflg)) {
error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
cnp->cn_pnlen, &bytes_copied);
} else {
error = copystr(CAST_DOWN(void *, ndp->ni_dirp), cnp->cn_pnbuf,
cnp->cn_pnlen, &bytes_copied);
}
if (error == ENAMETOOLONG && !(cnp->cn_flags & HASBUF)) {
cnp->cn_pnbuf = zalloc(ZV_NAMEI);
cnp->cn_flags |= HASBUF;
cnp->cn_pnlen = MAXPATHLEN;
bytes_copied = 0;
goto retry_copy;
}
if (error) {
goto error_out;
}
assert(bytes_copied <= MAXPATHLEN);
ndp->ni_pathlen = (u_int)bytes_copied;
bytes_copied = 0;
/*
* Since the name cache may contain positive entries of
* the incorrect case, force lookup() to bypass the cache
* and call directly into the filesystem for each path
* component. Note: the FS may still consult the cache,
* but can apply rules to validate the results.
*/
if (proc_is_forcing_hfs_case_sensitivity(p)) {
cnp->cn_flags |= CN_SKIPNAMECACHE;
}
#if CONFIG_VOLFS
/*
* Check for legacy volfs style pathnames.
*
* For compatibility reasons we currently allow these paths,
* but future versions of the OS may not support them.
*/
if (ndp->ni_pathlen >= VOLFS_MIN_PATH_LEN &&
cnp->cn_pnbuf[0] == '/' &&
cnp->cn_pnbuf[1] == '.' &&
cnp->cn_pnbuf[2] == 'v' &&
cnp->cn_pnbuf[3] == 'o' &&
cnp->cn_pnbuf[4] == 'l' &&
cnp->cn_pnbuf[5] == '/') {
char * realpath;
int realpath_err;
/* Attempt to resolve a legacy volfs style pathname. */
realpath = zalloc(ZV_NAMEI);
/*
* We only error out on the ENAMETOOLONG cases where we know that
* vfs_getrealpath translation succeeded but the path could not fit into
* MAXPATHLEN characters. In other failure cases, we may be dealing with a path
* that legitimately looks like /.vol/1234/567 and is not meant to be translated
*/
if ((realpath_err = vfs_getrealpath(&cnp->cn_pnbuf[6], realpath, MAXPATHLEN, ctx))) {
zfree(ZV_NAMEI, realpath);
if (realpath_err == ENOSPC || realpath_err == ENAMETOOLONG) {
error = ENAMETOOLONG;
goto error_out;
}
} else {
size_t tmp_len;
if (cnp->cn_flags & HASBUF) {
zfree(ZV_NAMEI, cnp->cn_pnbuf);
}
cnp->cn_pnbuf = realpath;
cnp->cn_pnlen = MAXPATHLEN;
tmp_len = strlen(realpath) + 1;
assert(tmp_len <= UINT_MAX);
ndp->ni_pathlen = (u_int)tmp_len;
cnp->cn_flags |= HASBUF | CN_VOLFSPATH;
}
}
#endif /* CONFIG_VOLFS */
#if CONFIG_AUDIT
/* If we are auditing the kernel pathname, save the user pathname */
if (cnp->cn_flags & AUDITVNPATH1) {
AUDIT_ARG(upath, ut->uu_cdir, cnp->cn_pnbuf, ARG_UPATH1);
}
if (cnp->cn_flags & AUDITVNPATH2) {
AUDIT_ARG(upath, ut->uu_cdir, cnp->cn_pnbuf, ARG_UPATH2);
}
#endif /* CONFIG_AUDIT */
/*
* Do not allow empty pathnames
*/
if (*cnp->cn_pnbuf == '\0') {
error = ENOENT;
goto error_out;
}
if (ndp->ni_flag & NAMEI_NOFOLLOW_ANY) {
ndp->ni_loopcnt = MAXSYMLINKS;
} else {
ndp->ni_loopcnt = 0;
}
/*
* determine the starting point for the translation.
*/
proc_dirs_lock_shared(p);
lck_rw_lock_shared(&rootvnode_rw_lock);
if (!(ndp->ni_flag & NAMEI_ROOTDIR)) {
if (fdt_flag_test(&p->p_fd, FD_CHROOT)) {
ndp->ni_rootdir = p->p_fd.fd_rdir;
} else {
ndp->ni_rootdir = rootvnode;
}
}
if (!ndp->ni_rootdir) {
if (ndp->ni_flag & NAMEI_ROOTDIR) {
panic("NAMEI_ROOTDIR is set but ni_rootdir is not\n");
} else if (fdt_flag_test(&p->p_fd, FD_CHROOT)) {
/* This should be a panic */
printf("p->p_fd.fd_rdir is not set\n");
} else {
printf("rootvnode is not set\n");
}
lck_rw_unlock_shared(&rootvnode_rw_lock);
proc_dirs_unlock_shared(p);
error = ENOENT;
goto error_out;
}
cnp->cn_nameptr = cnp->cn_pnbuf;
ndp->ni_usedvp = NULLVP;
if (*(cnp->cn_nameptr) == '/') {
while (*(cnp->cn_nameptr) == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
dp = ndp->ni_rootdir;
} else if (cnp->cn_flags & USEDVP) {
dp = ndp->ni_dvp;
ndp->ni_usedvp = dp;
usedvp_dp = dp;
} else {
dp = vfs_context_cwd(ctx);
}
if (dp == NULLVP || (dp->v_lflag & VL_DEAD)) {
dp = NULLVP;
lck_rw_unlock_shared(&rootvnode_rw_lock);
proc_dirs_unlock_shared(p);
error = ENOENT;
goto error_out;
}
/*
* We need our own usecount on the root vnode and the starting dir across
* the lookup. There's two things that be done here. We can hold the locks
* (which protect the existing usecounts on the directories) across the
* lookup or take our own usecount. Holding the locks across the lookup can
* cause deadlock issues if we re-enter namei on the same thread so the
* correct thing to do is to acquire our own usecount.
*
* Ideally, the usecount should be obtained by vnode_get->vnode_ref->vnode_put.
* However when this vnode is the rootvnode, that sequence will produce a
* lot of vnode mutex locks and unlocks on a single vnode (the rootvnode)
* and will be highly contended and degrade performance. Since we have
* an existing usecount protected by the locks we hold, we'll just use
* an atomic op to increment the usecount on a vnode which already has one
* and can't be released because we have the locks which protect against that
* happening.
*/
rootdir_with_usecount = ndp->ni_rootdir;
old_count = os_atomic_inc_orig(&rootdir_with_usecount->v_usecount, relaxed);
if (old_count < 1) {
panic("(1) invalid pre-increment usecount (%d) for rootdir vnode %p",
old_count, rootdir_with_usecount);
} else if (old_count == INT32_MAX) {
panic("(1) usecount overflow for vnode %p", rootdir_with_usecount);
}
if ((dp != rootdir_with_usecount) && (dp != usedvp_dp)) {
old_count = os_atomic_inc_orig(&dp->v_usecount, relaxed);
if (old_count < 1) {
panic("(2) invalid pre-increment usecount (%d) for vnode %p", old_count, dp);
} else if (old_count == INT32_MAX) {
panic("(2) usecount overflow for vnode %p", dp);
}
startdir_with_usecount = dp;
}
/* Now that we have our usecount, release the locks */
lck_rw_unlock_shared(&rootvnode_rw_lock);
proc_dirs_unlock_shared(p);
ndp->ni_dvp = NULLVP;
ndp->ni_vp = NULLVP;
for (;;) {
#if CONFIG_MACF
/*
* Give MACF policies a chance to reject the lookup
* before performing any filesystem operations.
* This hook is called before resolving the path and
* again each time a symlink is encountered.
* NB: policies receive path information as supplied
* by the caller and thus cannot be trusted.
*/
error = mac_vnode_check_lookup_preflight(ctx, dp, cnp->cn_nameptr, cnp->cn_namelen);
if (error) {
goto error_out;
}
#endif
ndp->ni_startdir = dp;
dp = NULLVP;
if ((error = lookup(ndp))) {
goto error_out;
}
/*
* Check for symbolic link
*/
if ((cnp->cn_flags & ISSYMLINK) == 0) {
if (startdir_with_usecount) {
vnode_rele(startdir_with_usecount);
startdir_with_usecount = NULLVP;
}
if (rootdir_with_usecount) {
lck_rw_lock_shared(&rootvnode_rw_lock);
if (rootdir_with_usecount == rootvnode) {
old_count = os_atomic_dec_orig(&rootdir_with_usecount->v_usecount, relaxed);
if (old_count < 2) {
/*
* There needs to have been at least 1 usecount left on the rootvnode
*/
panic("(3) Unexpected pre-decrement value (%d) of usecount for rootvnode %p",
old_count, rootdir_with_usecount);
}
rootdir_with_usecount = NULLVP;
}
lck_rw_unlock_shared(&rootvnode_rw_lock);
if (rootdir_with_usecount) {
vnode_rele(rootdir_with_usecount);
rootdir_with_usecount = NULLVP;
}
}
return 0;
}
continue_symlink:
/* Gives us a new path to process, and a starting dir */
error = lookup_handle_symlink(ndp, &dp, &dp_has_iocount, ctx);
if (error != 0) {
break;
}
if (dp_has_iocount) {
if ((dp != rootdir_with_usecount) && (dp != startdir_with_usecount) &&
(dp != usedvp_dp)) {
if (startdir_with_usecount) {
vnode_rele(startdir_with_usecount);
}
vnode_ref_ext(dp, 0, VNODE_REF_FORCE);
startdir_with_usecount = dp;
}
vnode_put(dp);
dp_has_iocount = false;
}
}
/*
* only come here if we fail to handle a SYMLINK...
* if either ni_dvp or ni_vp is non-NULL, then
* we need to drop the iocount that was picked
* up in the lookup routine
*/
out_drop:
if (ndp->ni_dvp) {
vnode_put(ndp->ni_dvp);
}
if (ndp->ni_vp) {
vnode_put(ndp->ni_vp);
}
error_out:
if (startdir_with_usecount) {
vnode_rele(startdir_with_usecount);
startdir_with_usecount = NULLVP;
}
if (rootdir_with_usecount) {
lck_rw_lock_shared(&rootvnode_rw_lock);
if (rootdir_with_usecount == rootvnode) {
old_count = os_atomic_dec_orig(&rootdir_with_usecount->v_usecount, relaxed);
if (old_count < 2) {
/*
* There needs to have been at least 1 usecount left on the rootvnode
*/
panic("(4) Unexpected pre-decrement value (%d) of usecount for rootvnode %p",
old_count, rootdir_with_usecount);
}
lck_rw_unlock_shared(&rootvnode_rw_lock);
} else {
lck_rw_unlock_shared(&rootvnode_rw_lock);
vnode_rele(rootdir_with_usecount);
}
rootdir_with_usecount = NULLVP;
}
if ((cnp->cn_flags & HASBUF)) {
cnp->cn_flags &= ~HASBUF;
zfree(ZV_NAMEI, cnp->cn_pnbuf);
}
cnp->cn_pnbuf = NULL;
ndp->ni_vp = NULLVP;
ndp->ni_dvp = NULLVP;
#if CONFIG_VOLFS
/*
* Deal with volfs fallout.
*
* At this point, if we were originally given a volfs path that
* looks like /.vol/123/456, then we would have had to convert it into
* a full path. Assuming that part worked properly, we will now attempt
* to conduct a lookup of the item in the namespace. Under normal
* circumstances, if a user looked up /tmp/foo and it was not there, it
* would be permissible to return ENOENT.
*
* However, we may not want to do that here. Specifically, the volfs path
* uniquely identifies a certain item in the namespace regardless of where it
* lives. If the item has moved in between the time we constructed the
* path and now, when we're trying to do a lookup/authorization on the full
* path, we may have gotten an ENOENT.
*
* At this point we can no longer tell if the path no longer exists
* or if the item in question no longer exists. It could have been renamed
* away, in which case the /.vol identifier is still valid.
*
* Do this dance a maximum of MAX_VOLFS_RESTARTS times.
*/
if ((error == ENOENT) && (ndp->ni_cnd.cn_flags & CN_VOLFSPATH)) {
if (volfs_restarts < MAX_VOLFS_RESTARTS) {
volfs_restarts++;
goto vnode_recycled;
}
}
#endif
if (error == ERECYCLE) {
/* vnode was recycled underneath us. re-drive lookup to start at
* the beginning again, since recycling invalidated last lookup*/
ndp->ni_cnd.cn_flags = cnpflags;
ndp->ni_dvp = usedvp;
goto vnode_recycled;
}
return error;
}
int
namei_compound_available(vnode_t dp, struct nameidata *ndp)
{
if ((ndp->ni_flag & NAMEI_COMPOUNDOPEN) != 0) {
return vnode_compound_open_available(dp);
}
return 0;
}
static int
lookup_authorize_search(vnode_t dp, struct componentname *cnp, int dp_authorized_in_cache, vfs_context_t ctx)
{
#if !CONFIG_MACF
#pragma unused(cnp)
#endif
int error;
if (!dp_authorized_in_cache) {
error = vnode_authorize(dp, NULL, KAUTH_VNODE_SEARCH, ctx);
if (error) {
return error;
}
}
#if CONFIG_MACF
error = mac_vnode_check_lookup(ctx, dp, cnp);
if (error) {
return error;
}
#endif /* CONFIG_MACF */
return 0;
}
static void
lookup_consider_update_cache(vnode_t dvp, vnode_t vp, struct componentname *cnp, int nc_generation)
{
int isdot_or_dotdot;
isdot_or_dotdot = (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') || (cnp->cn_flags & ISDOTDOT);
if (vp->v_name == NULL || vp->v_parent == NULLVP) {
int update_flags = 0;
if (isdot_or_dotdot == 0) {
if (vp->v_name == NULL) {
update_flags |= VNODE_UPDATE_NAME;
}
if (dvp != NULLVP && vp->v_parent == NULLVP) {
update_flags |= VNODE_UPDATE_PARENT;
}
if (update_flags) {
vnode_update_identity(vp, dvp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, update_flags);
}
}
}
if ((cnp->cn_flags & MAKEENTRY) && (vp->v_flag & VNCACHEABLE) && LIST_FIRST(&vp->v_nclinks) == NULL) {
/*
* missing from name cache, but should
* be in it... this can happen if volfs
* causes the vnode to be created or the
* name cache entry got recycled but the
* vnode didn't...
* check to make sure that ni_dvp is valid
* cache_lookup_path may return a NULL
* do a quick check to see if the generation of the
* directory matches our snapshot... this will get
* rechecked behind the name cache lock, but if it
* already fails to match, no need to go any further
*/
if (dvp != NULLVP && (nc_generation == dvp->v_nc_generation) && (!isdot_or_dotdot)) {
cache_enter_with_gen(dvp, vp, cnp, nc_generation);
}
}
}
#if NAMEDRSRCFORK
/*
* Can change ni_dvp and ni_vp. On success, returns with iocounts on stream vnode (always) and
* data fork if requested. On failure, returns with iocount data fork (always) and its parent directory
* (if one was provided).
*/
static int
lookup_handle_rsrc_fork(vnode_t dp, struct nameidata *ndp, struct componentname *cnp, int wantparent, vfs_context_t ctx)
{
vnode_t svp = NULLVP;
enum nsoperation nsop;
int nsflags;
int error;
if (dp->v_type != VREG) {
error = ENOENT;
goto out;
}
switch (cnp->cn_nameiop) {
case DELETE:
if (cnp->cn_flags & CN_ALLOWRSRCFORK) {
nsop = NS_DELETE;
} else {
error = EPERM;
goto out;
}
break;
case CREATE:
if (cnp->cn_flags & CN_ALLOWRSRCFORK) {
nsop = NS_CREATE;
} else {
error = EPERM;
goto out;
}
break;
case LOOKUP:
/* Make sure our lookup of "/..namedfork/rsrc" is allowed. */
if (cnp->cn_flags & CN_ALLOWRSRCFORK) {
nsop = NS_OPEN;
} else {
error = EPERM;
goto out;
}
break;
default:
error = EPERM;
goto out;
}
nsflags = 0;
if (cnp->cn_flags & CN_RAW_ENCRYPTED) {
nsflags |= NS_GETRAWENCRYPTED;
}
/* Ask the file system for the resource fork. */
error = vnode_getnamedstream(dp, &svp, XATTR_RESOURCEFORK_NAME, nsop, nsflags, ctx);
/* During a create, it OK for stream vnode to be missing. */
if (error == ENOATTR || error == ENOENT) {
error = (nsop == NS_CREATE) ? 0 : ENOENT;
}
if (error) {
goto out;
}
/* The "parent" of the stream is the file. */
if (wantparent) {
if (ndp->ni_dvp) {
vnode_put(ndp->ni_dvp);
}
ndp->ni_dvp = dp;
} else {
vnode_put(dp);
}
ndp->ni_vp = svp; /* on create this may be null */
/* Restore the truncated pathname buffer (for audits). */
if (ndp->ni_pathlen == 1 && ndp->ni_next[0] == '\0') {
/*
* While we replaced only '/' with '\0' and would ordinarily
* need to just switch that back, the buffer in which we did
* this may not be what the pathname buffer is now when symlinks
* are involved. If we just restore the "/" we will make the
* string not terminated anymore, so be safe and restore the
* entire suffix.
*/
strncpy(ndp->ni_next, _PATH_RSRCFORKSPEC, sizeof(_PATH_RSRCFORKSPEC));
cnp->cn_nameptr = ndp->ni_next + 1;
cnp->cn_namelen = sizeof(_PATH_RSRCFORKSPEC) - 1;
ndp->ni_next += cnp->cn_namelen;
if (ndp->ni_next[0] != '\0') {
panic("Incorrect termination of path in %s", __FUNCTION__);
}
}
cnp->cn_flags &= ~MAKEENTRY;
return 0;
out:
return error;
}
#endif /* NAMEDRSRCFORK */
/*
* iocounts in:
* --One on ni_vp. One on ni_dvp if there is more path, or we didn't come through the
* cache, or we came through the cache and the caller doesn't want the parent.
*
* iocounts out:
* --Leaves us in the correct state for the next step, whatever that might be.
* --If we find a symlink, returns with iocounts on both ni_vp and ni_dvp.
* --If we are to look up another component, then we have an iocount on ni_vp and
* nothing else.
* --If we are done, returns an iocount on ni_vp, and possibly on ni_dvp depending on nameidata flags.
* --In the event of an error, may return with ni_dvp NULL'ed out (in which case, iocount
* was dropped).
*/
static int
lookup_handle_found_vnode(struct nameidata *ndp, struct componentname *cnp, int rdonly,
int vbusyflags, int *keep_going, int nc_generation,
int wantparent, int atroot, vfs_context_t ctx)
{
vnode_t dp;
int error;
char *cp;
dp = ndp->ni_vp;
*keep_going = 0;
if (ndp->ni_vp == NULLVP) {
panic("NULL ni_vp in %s", __FUNCTION__);
}
if (atroot) {
goto nextname;
}
/*
* 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;
} else {
lookup_consider_update_cache(ndp->ni_dvp, dp, cnp, nc_generation);
}
/*
* Check to see if the vnode has been mounted on...
* if so find the root of the mounted file system.
* Updates ndp->ni_vp.
*/
error = lookup_traverse_mountpoints(ndp, cnp, dp, vbusyflags, ctx);
dp = ndp->ni_vp;
if (error) {
goto out;
}
#if CONFIG_MACF
if (vfs_flags(vnode_mount(dp)) & MNT_MULTILABEL) {
error = vnode_label(vnode_mount(dp), NULL, dp, NULL, 0, ctx);
if (error) {
goto out;
}
}
#endif
/*
* Check for symbolic link
*/
if ((dp->v_type == VLNK) &&
((cnp->cn_flags & FOLLOW) || (ndp->ni_flag & NAMEI_TRAILINGSLASH) || *ndp->ni_next == '/')) {
cnp->cn_flags |= ISSYMLINK;
*keep_going = 1;
return 0;
}
/*
* Check for bogus trailing slashes.
*/
if ((ndp->ni_flag & NAMEI_TRAILINGSLASH)) {
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto out;
}
ndp->ni_flag &= ~(NAMEI_TRAILINGSLASH);
}
#if NAMEDSTREAMS
/*
* Deny namei/lookup requests to resolve paths that point to shadow files.
* Access to shadow files must be conducted by explicit calls to VNOP_LOOKUP
* directly, and not use lookup/namei
*/
if (vnode_isshadow(dp)) {
error = ENOENT;
goto out;
}
#endif
nextname:
/*
* Not a symbolic link. If more pathname,
* continue at next component, else return.
*
* Definitely have a dvp if there's another slash
*/
if (*ndp->ni_next == '/') {
cnp->cn_nameptr = ndp->ni_next + 1;
ndp->ni_pathlen--;
while (*cnp->cn_nameptr == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
cp = cnp->cn_nameptr;
vnode_put(ndp->ni_dvp);
ndp->ni_dvp = NULLVP;
if (*cp == '\0') {
goto emptyname;
}
*keep_going = 1;
return 0;
}
/*
* Disallow directory write attempts on read-only file systems.
*/
if (rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto out;
}
/* If SAVESTART is set, we should have a dvp */
if (cnp->cn_flags & SAVESTART) {
/*
* note that we already hold a reference
* on both dp and ni_dvp, but for some reason
* can't get another one... in this case we
* need to do vnode_put on dp in 'bad2'
*/
if ((vnode_get(ndp->ni_dvp))) {
error = ENOENT;
goto out;
}
ndp->ni_startdir = ndp->ni_dvp;
}
if (!wantparent && ndp->ni_dvp) {
vnode_put(ndp->ni_dvp);
ndp->ni_dvp = NULLVP;
}
if (cnp->cn_flags & AUDITVNPATH1) {
AUDIT_ARG(vnpath, dp, ARG_VNODE1);
} else if (cnp->cn_flags & AUDITVNPATH2) {
AUDIT_ARG(vnpath, dp, ARG_VNODE2);
}
#if NAMEDRSRCFORK
/*
* Caller wants the resource fork.
*/
if ((cnp->cn_flags & CN_WANTSRSRCFORK) && (dp != NULLVP)) {
error = lookup_handle_rsrc_fork(dp, ndp, cnp, wantparent, ctx);
if (error != 0) {
goto out;
}
dp = ndp->ni_vp;
}
#endif
if (kdebug_enable) {
kdebug_lookup(ndp->ni_vp, cnp);
}
return 0;
emptyname:
error = lookup_handle_emptyname(ndp, cnp, wantparent);
if (error != 0) {
goto out;
}
return 0;
out:
return error;
}
/*
* Comes in iocount on ni_vp. May overwrite ni_dvp, but doesn't interpret incoming value.
*/
static int
lookup_handle_emptyname(struct nameidata *ndp, struct componentname *cnp, int wantparent)
{
vnode_t dp;
int error = 0;
dp = ndp->ni_vp;
cnp->cn_namelen = 0;
/*
* A degenerate name (e.g. / or "") which is a way of
* talking about a directory, e.g. like "/." or ".".
*/
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto out;
}
if (cnp->cn_nameiop == CREATE && dp == rootvnode) {
error = EEXIST;
goto out;
}
if (cnp->cn_nameiop != LOOKUP) {
error = EISDIR;
goto out;
}
if (wantparent) {
/*
* note that we already hold a reference
* on dp, but for some reason can't
* get another one... in this case we
* need to do vnode_put on dp in 'bad'
*/
if ((vnode_get(dp))) {
error = ENOENT;
goto out;
}
ndp->ni_dvp = dp;
}
cnp->cn_flags &= ~ISDOTDOT;
cnp->cn_flags |= ISLASTCN;
ndp->ni_next = cnp->cn_nameptr;
ndp->ni_vp = dp;
if (cnp->cn_flags & AUDITVNPATH1) {
AUDIT_ARG(vnpath, dp, ARG_VNODE1);
} else if (cnp->cn_flags & AUDITVNPATH2) {
AUDIT_ARG(vnpath, dp, ARG_VNODE2);
}
if (cnp->cn_flags & SAVESTART) {
panic("lookup: SAVESTART");
}
return 0;
out:
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 VNOP_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
*
* Returns: 0 Success
* ENOENT No such file or directory
* EBADF Bad file descriptor
* ENOTDIR Not a directory
* EROFS Read-only file system [CREATE]
* EISDIR Is a directory [CREATE]
* cache_lookup_path:ERECYCLE (vnode was recycled from underneath us, redrive lookup again)
* vnode_authorize:EROFS
* vnode_authorize:EACCES
* vnode_authorize:EPERM
* vnode_authorize:???
* VNOP_LOOKUP:ENOENT No such file or directory
* VNOP_LOOKUP:EJUSTRETURN Restart system call (INTERNAL)
* VNOP_LOOKUP:???
* VFS_ROOT:ENOTSUP
* VFS_ROOT:ENOENT
* VFS_ROOT:???
*/
int
lookup(struct nameidata *ndp)
{
char *cp; /* pointer into pathname argument */
vnode_t tdp; /* saved dp */
vnode_t dp; /* the directory we are searching */
int docache = 1; /* == 0 do not cache last component */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int dp_authorized = 0;
int error = 0;
struct componentname *cnp = &ndp->ni_cnd;
vfs_context_t ctx = cnp->cn_context;
int vbusyflags = 0;
int nc_generation = 0;
vnode_t last_dp = NULLVP;
int keep_going;
int atroot;
/*
* Setup: break out flag bits into variables.
*/
if (cnp->cn_flags & NOCACHE) {
docache = 0;
}
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
cnp->cn_consume = 0;
dp = ndp->ni_startdir;
ndp->ni_startdir = NULLVP;
if ((cnp->cn_flags & CN_NBMOUNTLOOK) != 0) {
vbusyflags = LK_NOWAIT;
}
cp = cnp->cn_nameptr;
if (*cp == '\0') {
if ((vnode_getwithref(dp))) {
dp = NULLVP;
error = ENOENT;
goto bad;
}
ndp->ni_vp = dp;
error = lookup_handle_emptyname(ndp, cnp, wantparent);
if (error) {
goto bad;
}
return 0;
}
dirloop:
atroot = 0;
ndp->ni_vp = NULLVP;
if ((error = cache_lookup_path(ndp, cnp, dp, ctx, &dp_authorized, last_dp))) {
dp = NULLVP;
goto bad;
}
if ((cnp->cn_flags & ISLASTCN)) {
if (docache) {
cnp->cn_flags |= MAKEENTRY;
}
} else {
cnp->cn_flags |= MAKEENTRY;
}
dp = ndp->ni_dvp;
if (ndp->ni_vp != NULLVP) {
/*
* cache_lookup_path returned a non-NULL ni_vp then,
* we're guaranteed that the dp is a VDIR, it's
* been authorized, and vp is not ".."
*
* make sure we don't try to enter the name back into
* the cache if this vp is purged before we get to that
* check since we won't have serialized behind whatever
* activity is occurring in the FS that caused the purge
*/
if (dp != NULLVP) {
nc_generation = dp->v_nc_generation - 1;
}
goto returned_from_lookup_path;
}
/*
* 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)) {
/*
* if this is a chroot'ed process, check if the current
* directory is still a subdirectory of the process's
* root directory.
*/
if (ndp->ni_rootdir && (ndp->ni_rootdir != rootvnode) &&
dp != ndp->ni_rootdir) {
int sdir_error;
int is_subdir = FALSE;
sdir_error = vnode_issubdir(dp, ndp->ni_rootdir,
&is_subdir, vfs_context_kernel());
/*
* If we couldn't determine if dp is a subdirectory of
* ndp->ni_rootdir (sdir_error != 0), we let the request
* proceed.
*/
if (!sdir_error && !is_subdir) {
vnode_put(dp);
dp = ndp->ni_rootdir;
/*
* There's a ref on the process's root directory
* but we can't use vnode_getwithref here as
* there is nothing preventing that ref being
* released by another thread.
*/
if (vnode_get(dp)) {
error = ENOENT;
goto bad;
}
}
}
for (;;) {
if (dp == ndp->ni_rootdir || dp == rootvnode) {
ndp->ni_dvp = dp;
ndp->ni_vp = dp;
/*
* we're pinned at the root
* we've already got one reference on 'dp'
* courtesy of cache_lookup_path... take
* another one for the ".."
* if we fail to get the new reference, we'll
* drop our original down in 'bad'
*/
if ((vnode_get(dp))) {
error = ENOENT;
goto bad;
}
atroot = 1;
goto returned_from_lookup_path;
}
if ((dp->v_flag & VROOT) == 0 ||
(cnp->cn_flags & NOCROSSMOUNT)) {
break;
}
if (dp->v_mount == NULL) { /* forced umount */
error = EBADF;
goto bad;
}
tdp = dp;
dp = tdp->v_mount->mnt_vnodecovered;
if ((vnode_getwithref(dp))) {
vnode_put(tdp);
dp = NULLVP;
error = ENOENT;
goto bad;
}
vnode_put(tdp);
ndp->ni_dvp = dp;
dp_authorized = 0;
}
}
/*
* We now have a segment name to search for, and a directory to search.
*/
#if CONFIG_UNION_MOUNTS
unionlookup:
#endif /* CONFIG_UNION_MOUNTS */
ndp->ni_vp = NULLVP;
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto lookup_error;
}
if ((cnp->cn_flags & DONOTAUTH) != DONOTAUTH) {
error = lookup_authorize_search(dp, cnp, dp_authorized, ctx);
if (error) {
goto lookup_error;
}
}
/*
* Now that we've authorized a lookup, can bail out if the filesystem
* will be doing a batched operation. Return an iocount on dvp.
*/
#if NAMEDRSRCFORK
if ((cnp->cn_flags & ISLASTCN) && namei_compound_available(dp, ndp) && !(cnp->cn_flags & CN_WANTSRSRCFORK)) {
#else
if ((cnp->cn_flags & ISLASTCN) && namei_compound_available(dp, ndp)) {
#endif /* NAMEDRSRCFORK */
ndp->ni_flag |= NAMEI_UNFINISHED;
ndp->ni_ncgeneration = dp->v_nc_generation;
return 0;
}
nc_generation = dp->v_nc_generation;
/*
* Note:
* Filesystems that support hardlinks may want to call vnode_update_identity
* if the lookup operation below will modify the in-core vnode to belong to a new point
* in the namespace. VFS cannot infer whether or not the look up operation makes the vnode
* name change or change parents. Without this, the lookup may make update
* filesystem-specific in-core metadata but fail to update the v_parent or v_name
* fields in the vnode. If VFS were to do this, it would be necessary to call
* vnode_update_identity on every lookup operation -- expensive!
*
* However, even with this in place, multiple lookups may occur in between this lookup
* and the subsequent vnop, so, at best, we could only guarantee that you would get a
* valid path back, and not necessarily the one that you wanted.
*
* Example:
* /tmp/a == /foo/b
*
* If you are now looking up /foo/b and the vnode for this link represents /tmp/a,
* vnode_update_identity will fix the parentage so that you can get /foo/b back
* through the v_parent chain (preventing you from getting /tmp/b back). It would
* not fix whether or not you should or should not get /tmp/a vs. /foo/b.
*/
error = VNOP_LOOKUP(dp, &ndp->ni_vp, cnp, ctx);
if (error) {
lookup_error:
#if CONFIG_UNION_MOUNTS
if ((error == ENOENT) &&
(dp->v_mount != NULL) &&
(dp->v_mount->mnt_flag & MNT_UNION)) {
tdp = dp;
error = lookup_traverse_union(tdp, &dp, ctx);
vnode_put(tdp);
if (error) {
dp = NULLVP;
goto bad;
}
ndp->ni_dvp = dp;
dp_authorized = 0;
goto unionlookup;
}
#endif /* CONFIG_UNION_MOUNTS */
if (error != EJUSTRETURN) {
goto bad;
}
if (ndp->ni_vp != NULLVP) {
panic("leaf should be empty");
}
#if NAMEDRSRCFORK
/*
* At this point, error should be EJUSTRETURN.
*
* If CN_WANTSRSRCFORK is set, that implies that the
* underlying filesystem could not find the "parent" of the
* resource fork (the data fork), and we are doing a lookup
* for a CREATE event.
*
* However, this should be converted to an error, as the
* failure to find this parent should disallow further
* progress to try and acquire a resource fork vnode.
*/
if (cnp->cn_flags & CN_WANTSRSRCFORK) {
error = ENOENT;
goto bad;
}
#endif
error = lookup_validate_creation_path(ndp);
if (error) {
goto bad;
}
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* referenced directory vnode in ndp->ni_dvp.
*/
if (cnp->cn_flags & SAVESTART) {
if ((vnode_get(ndp->ni_dvp))) {
error = ENOENT;
goto bad;
}
ndp->ni_startdir = ndp->ni_dvp;
}
if (!wantparent) {
vnode_put(ndp->ni_dvp);
}
if (kdebug_enable) {
kdebug_lookup(ndp->ni_dvp, cnp);
}
return 0;
}
returned_from_lookup_path:
/* We'll always have an iocount on ni_vp when this finishes. */
error = lookup_handle_found_vnode(ndp, cnp, rdonly, vbusyflags, &keep_going, nc_generation, wantparent, atroot, ctx);
if (error != 0) {
goto bad2;
}
if (keep_going) {
dp = ndp->ni_vp;
/* namei() will handle symlinks */
if ((dp->v_type == VLNK) &&
((cnp->cn_flags & FOLLOW) || (ndp->ni_flag & NAMEI_TRAILINGSLASH) || *ndp->ni_next == '/')) {
return 0;
}
/*
* Otherwise, there's more path to process.
* cache_lookup_path is now responsible for dropping io ref on dp
* when it is called again in the dirloop. This ensures we hold
* a ref on dp until we complete the next round of lookup.
*/
last_dp = dp;
goto dirloop;
}
return 0;
bad2:
if (ndp->ni_dvp) {
vnode_put(ndp->ni_dvp);
}
vnode_put(ndp->ni_vp);
ndp->ni_vp = NULLVP;
if (kdebug_enable) {
kdebug_lookup(dp, cnp);
}
return error;
bad:
if (dp) {
vnode_put(dp);
}
ndp->ni_vp = NULLVP;
if (kdebug_enable) {
kdebug_lookup(dp, cnp);
}
return error;
}
#if CONFIG_UNION_MOUNTS
/*
* Given a vnode in a union mount, traverse to the equivalent
* vnode in the underlying mount.
*/
int
lookup_traverse_union(vnode_t dvp, vnode_t *new_dvp, vfs_context_t ctx)
{
char *path = NULL, *pp;
const char *name, *np;
size_t len;
int error = 0;
struct nameidata nd;
vnode_t vp = dvp;
*new_dvp = NULL;
if (vp && vp->v_flag & VROOT) {
*new_dvp = vp->v_mount->mnt_vnodecovered;
if (vnode_getwithref(*new_dvp)) {
return ENOENT;
}
return 0;
}
path = zalloc_flags(ZV_NAMEI, Z_WAITOK | Z_NOFAIL);
/*
* Walk back up to the mountpoint following the
* v_parent chain and build a slash-separated path.
* Then lookup that path starting with the covered vnode.
*/
pp = path + (MAXPATHLEN - 1);
*pp = '\0';
while (1) {
name = vnode_getname(vp);
if (name == NULL) {
printf("lookup_traverse_union: null parent name: .%s\n", pp);
error = ENOENT;
goto done;
}
len = strlen(name);
if ((len + 1) > (size_t)(pp - path)) { // Enough space for this name ?
error = ENAMETOOLONG;
vnode_putname(name);
goto done;
}
for (np = name + len; len > 0; len--) { // Copy name backwards
*--pp = *--np;
}
vnode_putname(name);
vp = vp->v_parent;
if (vp == NULLVP || vp->v_flag & VROOT) {
break;
}
*--pp = '/';
}
/* Evaluate the path in the underlying mount */
NDINIT(&nd, LOOKUP, OP_LOOKUP, USEDVP, UIO_SYSSPACE, CAST_USER_ADDR_T(pp), ctx);
nd.ni_dvp = dvp->v_mount->mnt_vnodecovered;
error = namei(&nd);
if (error == 0) {
*new_dvp = nd.ni_vp;
}
nameidone(&nd);
done:
if (path) {
zfree(ZV_NAMEI, path);
}
return error;
}
#endif /* CONFIG_UNION_MOUNTS */
int
lookup_validate_creation_path(struct nameidata *ndp)
{
struct componentname *cnp = &ndp->ni_cnd;
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (cnp->cn_flags & RDONLY) {
return EROFS;
}
if ((cnp->cn_flags & ISLASTCN) && (ndp->ni_flag & NAMEI_TRAILINGSLASH) && !(cnp->cn_flags & WILLBEDIR)) {
return ENOENT;
}
return 0;
}
/*
* Modifies only ni_vp. Always returns with ni_vp still valid (iocount held).
*/
static int
lookup_traverse_mountpoints(struct nameidata *ndp, struct componentname *cnp, vnode_t dp,
int vbusyflags, vfs_context_t ctx)
{
mount_t mp;
vnode_t tdp;
int error = 0;
uint32_t depth = 0;
vnode_t mounted_on_dp;
int current_mount_generation = 0;
#if CONFIG_TRIGGERS
vnode_t triggered_dp = NULLVP;
int retry_cnt = 0;
#define MAX_TRIGGER_RETRIES 1
#endif
if (dp->v_type != VDIR || cnp->cn_flags & NOCROSSMOUNT) {
return 0;
}
mounted_on_dp = dp;
#if CONFIG_TRIGGERS
restart:
#endif
current_mount_generation = mount_generation;
while (dp->v_mountedhere) {
vnode_lock_spin(dp);
if ((mp = dp->v_mountedhere)) {
mp->mnt_crossref++;
vnode_unlock(dp);
} else {
vnode_unlock(dp);
break;
}
if (ISSET(mp->mnt_lflag, MNT_LFORCE)) {
mount_dropcrossref(mp, dp, 0);
break; // don't traverse into a forced unmount
}
if (vfs_busy(mp, vbusyflags)) {
mount_dropcrossref(mp, dp, 0);
if (vbusyflags == LK_NOWAIT) {
error = ENOENT;
goto out;
}
continue;
}
error = VFS_ROOT(mp, &tdp, ctx);
mount_dropcrossref(mp, dp, 0);
vfs_unbusy(mp);
if (error) {
goto out;
}
vnode_put(dp);
ndp->ni_vp = dp = tdp;
if (dp->v_type != VDIR) {
#if DEVELOPMENT || DEBUG
panic("%s : Root of filesystem not a directory",
__FUNCTION__);
#else
break;
#endif
}
depth++;
}
#if CONFIG_TRIGGERS
/*
* The triggered_dp check here is required but is susceptible to a
* (unlikely) race in which trigger mount is done from here and is
* unmounted before we get past vfs_busy above. We retry to deal with
* that case but it has the side effect of unwanted retries for
* "special" processes which don't want to trigger mounts.
*/
if (dp->v_resolve && retry_cnt < MAX_TRIGGER_RETRIES) {
error = vnode_trigger_resolve(dp, ndp, ctx);
if (error) {
goto out;
}
if (dp == triggered_dp) {
retry_cnt += 1;
} else {
retry_cnt = 0;
}
triggered_dp = dp;
goto restart;
}
#endif /* CONFIG_TRIGGERS */
if (depth) {
mp = mounted_on_dp->v_mountedhere;
if (mp) {
mount_lock_spin(mp);
mp->mnt_realrootvp_vid = dp->v_id;
mp->mnt_realrootvp = dp;
mp->mnt_generation = current_mount_generation;
mount_unlock(mp);
}
}
return 0;
out:
return error;
}
/*
* Takes ni_vp and ni_dvp non-NULL. Returns with *new_dp set to the location
* at which to start a lookup with a resolved path, and all other iocounts dropped.
*/
static int
lookup_handle_symlink(struct nameidata *ndp, vnode_t *new_dp, bool *new_dp_has_iocount, vfs_context_t ctx)
{
int error;
char *cp; /* pointer into pathname argument */
uio_t auio;
UIO_STACKBUF(uio_buf, 1);
int need_newpathbuf;
u_int linklen = 0;
struct componentname *cnp = &ndp->ni_cnd;
vnode_t dp;
char *tmppn;
u_int rsrclen = (cnp->cn_flags & CN_WANTSRSRCFORK) ? sizeof(_PATH_RSRCFORKSPEC) : 0;
bool dp_has_iocount = false;
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
return ELOOP;
}
#if CONFIG_MACF
if ((error = mac_vnode_check_readlink(ctx, ndp->ni_vp)) != 0) {
return error;
}
#endif /* MAC */
if (ndp->ni_pathlen > 1 || !(cnp->cn_flags & HASBUF)) {
need_newpathbuf = 1;
} else {
need_newpathbuf = 0;
}
if (need_newpathbuf) {
cp = zalloc(ZV_NAMEI);
} else {
cp = cnp->cn_pnbuf;
}
auio = uio_createwithbuffer(1, 0, UIO_SYSSPACE, UIO_READ, &uio_buf[0], sizeof(uio_buf));
uio_addiov(auio, CAST_USER_ADDR_T(cp), MAXPATHLEN);
error = VNOP_READLINK(ndp->ni_vp, auio, ctx);
if (!error) {
user_ssize_t resid = uio_resid(auio);
assert(resid <= MAXPATHLEN);
if (resid == MAXPATHLEN) {
linklen = 0;
} else {
/*
* Safe to set unsigned with a [larger] signed type here
* because 0 <= uio_resid <= MAXPATHLEN and MAXPATHLEN
* is only 1024.
*/
linklen = (u_int)strnlen(cp, MAXPATHLEN - (u_int)resid);
}
if (linklen == 0) {
error = ENOENT;
} else if (linklen + ndp->ni_pathlen + rsrclen > MAXPATHLEN) {
error = ENAMETOOLONG;
}
}
if (error) {
if (need_newpathbuf) {
zfree(ZV_NAMEI, cp);
}
return error;
}
if (need_newpathbuf) {
tmppn = cnp->cn_pnbuf;
bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
cnp->cn_pnbuf = cp;
cnp->cn_pnlen = MAXPATHLEN;
if ((cnp->cn_flags & HASBUF)) {
zfree(ZV_NAMEI, tmppn);
} else {
cnp->cn_flags |= HASBUF;
}
} else {
cnp->cn_pnbuf[linklen] = '\0';
}
ndp->ni_pathlen += linklen;
cnp->cn_nameptr = cnp->cn_pnbuf;
/*
* starting point for 'relative'
* symbolic link path
*/
dp = ndp->ni_dvp;
/*
* get rid of reference returned via 'lookup'
* ni_dvp is released only if we restart at /.
*/
vnode_put(ndp->ni_vp);
ndp->ni_vp = NULLVP;
ndp->ni_dvp = NULLVP;
dp_has_iocount = true;
/*
* Check if symbolic link restarts us at the root
*/
if (*(cnp->cn_nameptr) == '/') {
while (*(cnp->cn_nameptr) == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
if (linklen != 0) {
vnode_put(dp); /* ALWAYS have a dvp for a symlink */
dp_has_iocount = false;
if ((dp = ndp->ni_rootdir) == NULLVP) {
return ENOENT;
}
}
}
*new_dp = dp;
*new_dp_has_iocount = dp_has_iocount;
return 0;
}
/*
* relookup - lookup a path name component
* Used by lookup to re-aquire things.
*/
int
relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
{
struct vnode *dp = NULL; /* the directory we are searching */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int error = 0;
#ifdef NAMEI_DIAGNOSTIC
int i, newhash; /* DEBUG: check name hash */
char *cp; /* DEBUG: check name ptr/len */
#endif
vfs_context_t ctx = cnp->cn_context;
/*
* Setup: break out flag bits into variables.
*/
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
if (cnp->cn_flags & NOCACHE) {
cnp->cn_flags &= ~MAKEENTRY;
} else {
cnp->cn_flags |= MAKEENTRY;
}
dp = dvp;
/*
* 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 ((vnode_get(dp))) {
error = ENOENT;
goto bad;
}
*vpp = dp;
if (cnp->cn_flags & SAVESTART) {
panic("lookup: SAVESTART");
}
return 0;
}
/*
* We now have a segment name to search for, and a directory to search.
*/
if ((error = VNOP_LOOKUP(dp, vpp, cnp, ctx))) {
if (error != EJUSTRETURN) {
goto bad;
}
#if DIAGNOSTIC
if (*vpp != NULL) {
panic("leaf should be empty");
}
#endif
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (rdonly) {
error = EROFS;
goto bad;
}
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* (possibly locked) directory inode in ndp->ni_dvp.
*/
return 0;
}
dp = *vpp;
#if DIAGNOSTIC
/*
* Check for symbolic link
*/
if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW)) {
panic("relookup: symlink found.");
}
#endif
/*
* Disallow directory write attempts on read-only file systems.
*/
if (rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto bad2;
}
/* ASSERT(dvp == ndp->ni_startdir) */
return 0;
bad2:
vnode_put(dp);
bad:
*vpp = NULL;
return error;
}
/*
* Free pathname buffer
*/
void
nameidone(struct nameidata *ndp)
{
if (ndp->ni_cnd.cn_flags & HASBUF) {
char *tmp = ndp->ni_cnd.cn_pnbuf;
ndp->ni_cnd.cn_pnbuf = NULL;
ndp->ni_cnd.cn_flags &= ~HASBUF;
zfree(ZV_NAMEI, tmp);
}
}
/*
* Log (part of) a pathname using kdebug, as used by fs_usage. The path up to
* and including the current component name are logged. Up to NUMPARMS * 4
* bytes of pathname will be logged. If the path to be logged is longer than
* that, then the last NUMPARMS * 4 bytes are logged. That is, the truncation
* removes the leading portion of the path.
*
* The logging is done via multiple KDBG_RELEASE calls. The first one is marked
* with DBG_FUNC_START. The last one is marked with DBG_FUNC_END (in addition
* to DBG_FUNC_START if it is also the first). There may be intermediate ones
* with neither DBG_FUNC_START nor DBG_FUNC_END.
*
* The first event passes the vnode pointer and 24 or 32 (on K32, 12 or 24)
* bytes of pathname. The remaining events add 32 (on K32, 16) bytes of
* pathname each. The minimum number of events required to pass the path are
* used. Any excess padding in the final event (because not all of the 24 or 32
* (on K32, 12 or 16) bytes are needed for the remainder of the path) is set to
* zero bytes, or '>' if there is more path beyond the current component name
* (usually because an intermediate component was not found).
*
* NOTE: If the path length is greater than NUMPARMS * 4, or is not of the form
* 24 + N * 32 (or on K32, 12 + N * 16), there will be no padding.
*/
#if (KDEBUG_LEVEL >= KDEBUG_LEVEL_IST)
void
kdebug_vfs_lookup(unsigned long *path_words, int path_len, void *vnp,
uint32_t flags)
{
bool noprocfilt = flags & KDBG_VFS_LOOKUP_FLAG_NOPROCFILT;
assert(path_len >= 0);
int code = ((flags & KDBG_VFS_LOOKUP_FLAG_LOOKUP) ? VFS_LOOKUP :
VFS_LOOKUP_DONE) | DBG_FUNC_START;
if (path_len <= (3 * (int)sizeof(long))) {
code |= DBG_FUNC_END;
}
if (noprocfilt) {
KDBG_RELEASE_NOPROCFILT(code, kdebug_vnode(vnp), path_words[0],
path_words[1], path_words[2]);
} else {
KDBG_RELEASE(code, kdebug_vnode(vnp), path_words[0], path_words[1],
path_words[2]);
}
code &= ~DBG_FUNC_START;
for (int i = 3; i * (int)sizeof(long) < path_len; i += 4) {
if ((i + 4) * (int)sizeof(long) >= path_len) {
code |= DBG_FUNC_END;
}
if (noprocfilt) {
KDBG_RELEASE_NOPROCFILT(code, path_words[i], path_words[i + 1],
path_words[i + 2], path_words[i + 3]);
} else {
KDBG_RELEASE(code, path_words[i], path_words[i + 1],
path_words[i + 2], path_words[i + 3]);
}
}
}
void
kdebug_lookup_gen_events(long *path_words, int path_len, void *vnp, bool lookup)
{
assert(path_len >= 0);
kdebug_vfs_lookup((unsigned long *)path_words, path_len, vnp,
lookup ? KDBG_VFS_LOOKUP_FLAG_LOOKUP : 0);
}
void
kdebug_lookup(vnode_t vnp, struct componentname *cnp)
{
unsigned long path_words[NUMPARMS];
/*
* Truncate the leading portion of the path to fit in path_words.
*/
char *path_end = cnp->cn_nameptr + cnp->cn_namelen;
size_t path_len = MIN(path_end - cnp->cn_pnbuf,
(ssize_t)sizeof(path_words));
assert(path_len >= 0);
char *path_trunc = path_end - path_len;
memcpy(path_words, path_trunc, path_len);
/*
* Pad with '\0' or '>'.
*/
if (path_len < (ssize_t)sizeof(path_words)) {
bool complete_str = *(cnp->cn_nameptr + cnp->cn_namelen) == '\0';
memset((char *)path_words + path_len, complete_str ? '\0' : '>',
sizeof(path_words) - path_len);
}
kdebug_vfs_lookup(path_words, (int)path_len, vnp, KDBG_VFS_LOOKUP_FLAG_LOOKUP);
}
#else /* (KDEBUG_LEVEL >= KDEBUG_LEVEL_IST) */
void
kdebug_vfs_lookup(long *dbg_parms __unused, int dbg_namelen __unused,
void *dp __unused, __unused uint32_t flags)
{
}
static void
kdebug_lookup(struct vnode *dp __unused, struct componentname *cnp __unused)
{
}
#endif /* (KDEBUG_LEVEL >= KDEBUG_LEVEL_IST) */
int
vfs_getbyid(fsid_t *fsid, ino64_t ino, vnode_t *vpp, vfs_context_t ctx)
{
mount_t mp;
int error;
mp = mount_lookupby_volfsid(fsid->val[0], 1);
if (mp == NULL) {
return EINVAL;
}
/* Get the target vnode. */
if (ino == 2) {
error = VFS_ROOT(mp, vpp, ctx);
} else {
error = VFS_VGET(mp, ino, vpp, ctx);
}
vfs_unbusy(mp);
return error;
}
/*
* Obtain the real path from a legacy volfs style path.
*
* Valid formats of input path:
*
* "555/@"
* "555/2"
* "555/123456"
* "555/123456/foobar"
*
* Where:
* 555 represents the volfs file system id
* '@' and '2' are aliases to the root of a file system
* 123456 represents a file id
* "foobar" represents a file name
*/
#if CONFIG_VOLFS
static int
vfs_getrealpath(const char * path, char * realpath, size_t bufsize, vfs_context_t ctx)
{
vnode_t vp;
struct mount *mp = NULL;
char *str;
char ch;
unsigned long id;
ino64_t ino;
int error;
int length;
/* Get file system id and move str to next component. */
id = strtoul(path, &str, 10);
if (id == 0 || str[0] != '/') {
return EINVAL;
}
while (*str == '/') {
str++;
}
ch = *str;
if (id > INT_MAX) {
return ENOENT;
}
mp = mount_lookupby_volfsid((int)id, 1);
if (mp == NULL) {
return EINVAL; /* unexpected failure */
}
/* Check for an alias to a file system root. */
if (ch == '@' && str[1] == '\0') {
ino = 2;
str++;
} else {
/* Get file id and move str to next component. */
ino = strtouq(str, &str, 10);
}
/* Get the target vnode. */
if (ino == 2) {
struct vfs_attr vfsattr;
int use_vfs_root = TRUE;
VFSATTR_INIT(&vfsattr);
VFSATTR_WANTED(&vfsattr, f_capabilities);
if (vfs_getattr(mp, &vfsattr, vfs_context_kernel()) == 0 &&
VFSATTR_IS_SUPPORTED(&vfsattr, f_capabilities)) {
if ((vfsattr.f_capabilities.capabilities[VOL_CAPABILITIES_FORMAT] & VOL_CAP_FMT_VOL_GROUPS) &&
(vfsattr.f_capabilities.valid[VOL_CAPABILITIES_FORMAT] & VOL_CAP_FMT_VOL_GROUPS)) {
use_vfs_root = FALSE;
}
}
if (use_vfs_root) {
error = VFS_ROOT(mp, &vp, ctx);
} else {
error = VFS_VGET(mp, ino, &vp, ctx);
}
} else {
error = VFS_VGET(mp, ino, &vp, ctx);
}
vfs_unbusy(mp);
if (error) {
goto out;
}
realpath[0] = '\0';
/* Get the absolute path to this vnode. */
error = build_path(vp, realpath, (int)bufsize, &length, 0, ctx);
vnode_put(vp);
if (error == 0 && *str != '\0') {
size_t attempt = strlcat(realpath, str, MAXPATHLEN);
if (attempt > MAXPATHLEN) {
error = ENAMETOOLONG;
}
}
out:
return error;
}
#endif
void
lookup_compound_vnop_post_hook(int error, vnode_t dvp, vnode_t vp, struct nameidata *ndp, int did_create)
{
if (error == 0 && vp == NULLVP) {
panic("NULL vp with error == 0.");
}
/*
* We don't want to do any of this if we didn't use the compound vnop
* to perform the lookup... i.e. if we're allowing and using the legacy pattern,
* where we did a full lookup.
*/
if ((ndp->ni_flag & NAMEI_COMPOUND_OP_MASK) == 0) {
return;
}
/*
* If we're going to continue the lookup, we'll handle
* all lookup-related updates at that time.
*/
if (error == EKEEPLOOKING) {
return;
}
/*
* Only audit or update cache for *found* vnodes. For creation
* neither would happen in the non-compound-vnop case.
*/
if ((vp != NULLVP) && !did_create) {
/*
* If MAKEENTRY isn't set, and we've done a successful compound VNOP,
* then we certainly don't want to update cache or identity.
*/
if ((error != 0) || (ndp->ni_cnd.cn_flags & MAKEENTRY)) {
lookup_consider_update_cache(dvp, vp, &ndp->ni_cnd, ndp->ni_ncgeneration);
}
if (ndp->ni_cnd.cn_flags & AUDITVNPATH1) {
AUDIT_ARG(vnpath, vp, ARG_VNODE1);
} else if (ndp->ni_cnd.cn_flags & AUDITVNPATH2) {
AUDIT_ARG(vnpath, vp, ARG_VNODE2);
}
}
/*
* If you created (whether you opened or not), cut a lookup tracepoint
* for the parent dir (as would happen without a compound vnop). Note: we may need
* a vnode despite failure in this case!
*
* If you did not create:
* Found child (succeeded or not): cut a tracepoint for the child.
* Did not find child: cut a tracepoint with the parent.
*/
if (kdebug_enable) {
kdebug_lookup(vp ? vp : dvp, &ndp->ni_cnd);
}
}
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