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NetBSD/sys/kern/vfs_lookup.c

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/* $NetBSD: vfs_lookup.c,v 1.121 2010/01/08 11:35:10 pooka Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. 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
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.121 2010/01/08 11:35:10 pooka Exp $");
#include "opt_magiclinks.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/syslimits.h>
#include <sys/time.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/errno.h>
#include <sys/filedesc.h>
#include <sys/hash.h>
#include <sys/proc.h>
#include <sys/syslog.h>
#include <sys/kauth.h>
#include <sys/ktrace.h>
#ifndef MAGICLINKS
#define MAGICLINKS 0
#endif
struct pathname_internal {
char *pathbuf;
bool needfree;
};
int vfs_magiclinks = MAGICLINKS;
pool_cache_t pnbuf_cache; /* pathname buffer cache */
/*
* Substitute replacement text for 'magic' strings in symlinks.
* Returns 0 if successful, and returns non-zero if an error
* occurs. (Currently, the only possible error is running out
* of temporary pathname space.)
*
* Looks for "@<string>" and "@<string>/", where <string> is a
* recognized 'magic' string. Replaces the "@<string>" with the
* appropriate replacement text. (Note that in some cases the
* replacement text may have zero length.)
*
* This would have been table driven, but the variance in
* replacement strings (and replacement string lengths) made
* that impractical.
*/
#define VNL(x) \
(sizeof(x) - 1)
#define VO '{'
#define VC '}'
#define MATCH(str) \
((termchar == '/' && i + VNL(str) == *len) || \
(i + VNL(str) < *len && \
cp[i + VNL(str)] == termchar)) && \
!strncmp((str), &cp[i], VNL(str))
#define SUBSTITUTE(m, s, sl) \
if ((newlen + (sl)) >= MAXPATHLEN) \
return 1; \
i += VNL(m); \
if (termchar != '/') \
i++; \
(void)memcpy(&tmp[newlen], (s), (sl)); \
newlen += (sl); \
change = 1; \
termchar = '/';
static int
symlink_magic(struct proc *p, char *cp, size_t *len)
{
char *tmp;
size_t change, i, newlen, slen;
char termchar = '/';
char idtmp[11]; /* enough for 32 bit *unsigned* integer */
tmp = PNBUF_GET();
for (change = i = newlen = 0; i < *len; ) {
if (cp[i] != '@') {
tmp[newlen++] = cp[i++];
continue;
}
i++;
/* Check for @{var} syntax. */
if (cp[i] == VO) {
termchar = VC;
i++;
}
/*
* The following checks should be ordered according
* to frequency of use.
*/
if (MATCH("machine_arch")) {
slen = VNL(MACHINE_ARCH);
SUBSTITUTE("machine_arch", MACHINE_ARCH, slen);
} else if (MATCH("machine")) {
slen = VNL(MACHINE);
SUBSTITUTE("machine", MACHINE, slen);
} else if (MATCH("hostname")) {
SUBSTITUTE("hostname", hostname, hostnamelen);
} else if (MATCH("osrelease")) {
slen = strlen(osrelease);
SUBSTITUTE("osrelease", osrelease, slen);
} else if (MATCH("emul")) {
slen = strlen(p->p_emul->e_name);
SUBSTITUTE("emul", p->p_emul->e_name, slen);
} else if (MATCH("kernel_ident")) {
slen = strlen(kernel_ident);
SUBSTITUTE("kernel_ident", kernel_ident, slen);
} else if (MATCH("domainname")) {
SUBSTITUTE("domainname", domainname, domainnamelen);
} else if (MATCH("ostype")) {
slen = strlen(ostype);
SUBSTITUTE("ostype", ostype, slen);
} else if (MATCH("uid")) {
slen = snprintf(idtmp, sizeof(idtmp), "%u",
kauth_cred_geteuid(kauth_cred_get()));
SUBSTITUTE("uid", idtmp, slen);
} else if (MATCH("ruid")) {
slen = snprintf(idtmp, sizeof(idtmp), "%u",
kauth_cred_getuid(kauth_cred_get()));
SUBSTITUTE("ruid", idtmp, slen);
} else if (MATCH("gid")) {
slen = snprintf(idtmp, sizeof(idtmp), "%u",
kauth_cred_getegid(kauth_cred_get()));
SUBSTITUTE("gid", idtmp, slen);
} else if (MATCH("rgid")) {
slen = snprintf(idtmp, sizeof(idtmp), "%u",
kauth_cred_getgid(kauth_cred_get()));
SUBSTITUTE("rgid", idtmp, slen);
} else {
tmp[newlen++] = '@';
if (termchar == VC)
tmp[newlen++] = VO;
}
}
if (change) {
(void)memcpy(cp, tmp, newlen);
*len = newlen;
}
PNBUF_PUT(tmp);
return 0;
}
#undef VNL
#undef VO
#undef VC
#undef MATCH
#undef SUBSTITUTE
/*
* 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
* }
*/
/*
* Internal state for a namei operation.
*/
struct namei_state {
struct nameidata *ndp;
struct componentname *cnp;
/* used by the pieces of namei */
struct vnode *namei_startdir; /* The directory namei() starts from. */
/* used by the pieces of lookup */
int lookup_alldone;
int docache; /* == 0 do not cache last component */
int rdonly; /* lookup read-only flag bit */
struct vnode *dp; /* the directory we are searching */
int slashes;
};
/* XXX reorder things to make this decl unnecessary */
static int do_lookup(struct namei_state *state);
/*
* Initialize the namei working state.
*/
static void
namei_init(struct namei_state *state, struct nameidata *ndp)
{
state->ndp = ndp;
state->cnp = &ndp->ni_cnd;
state->namei_startdir = NULL;
state->lookup_alldone = 0;
state->docache = 0;
state->rdonly = 0;
state->dp = NULL;
state->slashes = 0;
}
/*
* Clean up the working namei state, leaving things ready for return
* from namei.
*/
static void
namei_cleanup(struct namei_state *state)
{
KASSERT(state->cnp == &state->ndp->ni_cnd);
//KASSERT(state->namei_startdir == NULL); // not yet
/* nothing for now */
(void)state;
}
//////////////////////////////
/*
* Start up namei. Early portion.
*
* This is divided from namei_start2 by the emul_retry: point.
*/
static void
namei_start1(struct namei_state *state)
{
#ifdef DIAGNOSTIC
if (!state->cnp->cn_cred)
panic("namei: bad cred/proc");
if (state->cnp->cn_nameiop & (~OPMASK))
panic("namei: nameiop contaminated with flags");
if (state->cnp->cn_flags & OPMASK)
panic("namei: flags contaminated with nameiops");
#endif
/*
* Get a buffer for the name to be translated, and copy the
* name into the buffer.
*/
if ((state->cnp->cn_flags & HASBUF) == 0)
state->cnp->cn_pnbuf = PNBUF_GET();
}
/*
* Start up namei. Copy the path, find the root dir and cwd, establish
* the starting directory for lookup, and lock it.
*/
static int
namei_start2(struct namei_state *state)
{
struct nameidata *ndp = state->ndp;
struct componentname *cnp = state->cnp;
struct cwdinfo *cwdi; /* pointer to cwd state */
struct lwp *self = curlwp; /* thread doing namei() */
int error;
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);
/*
* POSIX.1 requirement: "" is not a valid file name.
*/
if (!error && ndp->ni_pathlen == 1)
error = ENOENT;
if (error) {
PNBUF_PUT(cnp->cn_pnbuf);
ndp->ni_vp = NULL;
return (error);
}
ndp->ni_loopcnt = 0;
/*
* Get root directory for the translation.
*/
cwdi = self->l_proc->p_cwdi;
rw_enter(&cwdi->cwdi_lock, RW_READER);
state->namei_startdir = cwdi->cwdi_rdir;
if (state->namei_startdir == NULL)
state->namei_startdir = rootvnode;
ndp->ni_rootdir = state->namei_startdir;
/*
* Check if starting from root directory or current directory.
*/
if (cnp->cn_pnbuf[0] == '/') {
if (cnp->cn_flags & TRYEMULROOT) {
if (cnp->cn_flags & EMULROOTSET) {
/* Called from (eg) emul_find_interp() */
state->namei_startdir = ndp->ni_erootdir;
} else {
if (cwdi->cwdi_edir == NULL
|| (cnp->cn_pnbuf[1] == '.'
&& cnp->cn_pnbuf[2] == '.'
&& cnp->cn_pnbuf[3] == '/')) {
ndp->ni_erootdir = NULL;
} else {
state->namei_startdir = cwdi->cwdi_edir;
ndp->ni_erootdir = state->namei_startdir;
}
}
} else {
ndp->ni_erootdir = NULL;
if (cnp->cn_flags & NOCHROOT)
state->namei_startdir = ndp->ni_rootdir = rootvnode;
}
} else {
state->namei_startdir = cwdi->cwdi_cdir;
ndp->ni_erootdir = NULL;
}
vref(state->namei_startdir);
rw_exit(&cwdi->cwdi_lock);
/*
* Ktrace it.
*/
if (ktrpoint(KTR_NAMEI)) {
if (ndp->ni_erootdir != NULL) {
/*
* To make any sense, the trace entry need to have the
* text of the emulation path prepended.
* Usually we can get this from the current process,
* but when called from emul_find_interp() it is only
* in the exec_package - so we get it passed in ni_next
* (this is a hack).
*/
const char *emul_path;
if (cnp->cn_flags & EMULROOTSET)
emul_path = ndp->ni_next;
else
emul_path = self->l_proc->p_emul->e_path;
ktrnamei2(emul_path, strlen(emul_path),
cnp->cn_pnbuf, ndp->ni_pathlen);
} else
ktrnamei(cnp->cn_pnbuf, ndp->ni_pathlen);
}
vn_lock(state->namei_startdir, LK_EXCLUSIVE | LK_RETRY);
return 0;
}
/*
* Undo namei_start: unlock and release the current lookup directory,
* and discard the path buffer.
*/
static void
namei_end(struct namei_state *state)
{
vput(state->namei_startdir);
PNBUF_PUT(state->cnp->cn_pnbuf);
//state->cnp->cn_pnbuf = NULL; // not yet (just in case) (XXX)
}
/*
* Check for being at a symlink.
*/
static inline int
namei_atsymlink(struct namei_state *state)
{
return (state->cnp->cn_flags & ISSYMLINK) != 0;
}
/*
* Follow a symlink.
*/
static inline int
namei_follow(struct namei_state *state)
{
struct nameidata *ndp = state->ndp;
struct componentname *cnp = state->cnp;
struct lwp *self = curlwp; /* thread doing namei() */
struct iovec aiov; /* uio for reading symbolic links */
struct uio auio;
char *cp; /* pointer into pathname argument */
size_t linklen;
int error;
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
return ELOOP;
}
if (ndp->ni_vp->v_mount->mnt_flag & MNT_SYMPERM) {
error = VOP_ACCESS(ndp->ni_vp, VEXEC, cnp->cn_cred);
if (error != 0)
return error;
}
if (ndp->ni_pathlen > 1)
cp = PNBUF_GET();
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_resid = MAXPATHLEN;
UIO_SETUP_SYSSPACE(&auio);
error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
if (error) {
badlink:
if (ndp->ni_pathlen > 1)
PNBUF_PUT(cp);
return error;
}
linklen = MAXPATHLEN - auio.uio_resid;
if (linklen == 0) {
error = ENOENT;
goto badlink;
}
/*
* Do symlink substitution, if appropriate, and
* check length for potential overflow.
*/
if ((vfs_magiclinks &&
symlink_magic(self->l_proc, cp, &linklen)) ||
(linklen + ndp->ni_pathlen >= MAXPATHLEN)) {
error = ENAMETOOLONG;
goto badlink;
}
if (ndp->ni_pathlen > 1) {
memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen);
PNBUF_PUT(cnp->cn_pnbuf);
cnp->cn_pnbuf = cp;
} else
cnp->cn_pnbuf[linklen] = '\0';
ndp->ni_pathlen += linklen;
vput(ndp->ni_vp);
state->namei_startdir = ndp->ni_dvp;
/*
* Check if root directory should replace current directory.
*/
if (cnp->cn_pnbuf[0] == '/') {
vput(state->namei_startdir);
/* Keep absolute symbolic links inside emulation root */
state->namei_startdir = ndp->ni_erootdir;
if (state->namei_startdir == NULL || (cnp->cn_pnbuf[1] == '.'
&& cnp->cn_pnbuf[2] == '.'
&& cnp->cn_pnbuf[3] == '/')) {
ndp->ni_erootdir = NULL;
state->namei_startdir = ndp->ni_rootdir;
}
vref(state->namei_startdir);
vn_lock(state->namei_startdir, LK_EXCLUSIVE | LK_RETRY);
}
return 0;
}
//////////////////////////////
static int
do_namei(struct namei_state *state)
{
int error;
struct nameidata *ndp = state->ndp;
struct componentname *cnp = state->cnp;
KASSERT(cnp == &ndp->ni_cnd);
namei_start1(state);
emul_retry:
error = namei_start2(state);
if (error) {
return error;
}
/* Loop through symbolic links */
for (;;) {
if (state->namei_startdir->v_mount == NULL) {
/* Give up if the directory is no longer mounted */
namei_end(state);
return (ENOENT);
}
cnp->cn_nameptr = cnp->cn_pnbuf;
ndp->ni_startdir = state->namei_startdir;
error = do_lookup(state);
if (error != 0) {
/* XXX this should use namei_end() */
if (ndp->ni_dvp) {
vput(ndp->ni_dvp);
}
if (ndp->ni_erootdir != NULL) {
/* Retry the whole thing from the normal root */
cnp->cn_flags &= ~TRYEMULROOT;
goto emul_retry;
}
PNBUF_PUT(cnp->cn_pnbuf);
return (error);
}
/*
* Check for symbolic link
*/
if (namei_atsymlink(state)) {
error = namei_follow(state);
if (error) {
KASSERT(ndp->ni_dvp != ndp->ni_vp);
vput(ndp->ni_dvp);
vput(ndp->ni_vp);
ndp->ni_vp = NULL;
PNBUF_PUT(cnp->cn_pnbuf);
return error;
}
}
else {
break;
}
}
/*
* Done
*/
if ((cnp->cn_flags & LOCKPARENT) == 0 && ndp->ni_dvp) {
if (ndp->ni_dvp == ndp->ni_vp) {
vrele(ndp->ni_dvp);
} else {
vput(ndp->ni_dvp);
}
}
if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0) {
PNBUF_PUT(cnp->cn_pnbuf);
#if defined(DIAGNOSTIC)
cnp->cn_pnbuf = NULL;
#endif /* defined(DIAGNOSTIC) */
} else {
cnp->cn_flags |= HASBUF;
}
return 0;
}
int
namei(struct nameidata *ndp)
{
struct namei_state state;
int error;
namei_init(&state, ndp);
error = do_namei(&state);
namei_cleanup(&state);
return error;
}
/*
* Determine the namei hash (for cn_hash) for name.
* If *ep != NULL, hash from name to ep-1.
* If *ep == NULL, hash from name until the first NUL or '/', and
* return the location of this termination character in *ep.
*
* This function returns an equivalent hash to the MI hash32_strn().
* The latter isn't used because in the *ep == NULL case, determining
* the length of the string to the first NUL or `/' and then calling
* hash32_strn() involves unnecessary double-handling of the data.
*/
uint32_t
namei_hash(const char *name, const char **ep)
{
uint32_t hash;
hash = HASH32_STR_INIT;
if (*ep != NULL) {
for (; name < *ep; name++)
hash = hash * 33 + *(const uint8_t *)name;
} else {
for (; *name != '\0' && *name != '/'; name++)
hash = hash * 33 + *(const uint8_t *)name;
*ep = name;
}
return (hash + (hash >> 5));
}
/*
* 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. 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, locked.
* 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
*/
/*
* Begin lookup().
*/
static int
lookup_start(struct namei_state *state)
{
const char *cp; /* pointer into pathname argument */
struct componentname *cnp = state->cnp;
struct nameidata *ndp = state->ndp;
KASSERT(cnp == &ndp->ni_cnd);
state->lookup_alldone = 0;
state->dp = NULL;
/*
* Setup: break out flag bits into variables.
*/
state->docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
if (cnp->cn_nameiop == DELETE)
state->docache = 0;
state->rdonly = cnp->cn_flags & RDONLY;
ndp->ni_dvp = NULL;
cnp->cn_flags &= ~ISSYMLINK;
state->dp = ndp->ni_startdir;
ndp->ni_startdir = NULLVP;
/*
* If we have a leading string of slashes, remove them, and just make
* sure the current node is a directory.
*/
cp = cnp->cn_nameptr;
if (*cp == '/') {
do {
cp++;
} while (*cp == '/');
ndp->ni_pathlen -= cp - cnp->cn_nameptr;
cnp->cn_nameptr = cp;
if (state->dp->v_type != VDIR) {
vput(state->dp);
return ENOTDIR;
}
/*
* If we've exhausted the path name, then just return the
* current node.
*/
if (cnp->cn_nameptr[0] == '\0') {
ndp->ni_vp = state->dp;
cnp->cn_flags |= ISLASTCN;
/* bleh */
state->lookup_alldone = 1;
return 0;
}
}
return 0;
}
static int
lookup_parsepath(struct namei_state *state)
{
const char *cp; /* pointer into pathname argument */
struct componentname *cnp = state->cnp;
struct nameidata *ndp = state->ndp;
KASSERT(cnp == &ndp->ni_cnd);
/*
* Search a new directory.
*
* The cn_hash value is for use by vfs_cache.
* The last component of the filename is left accessible via
* cnp->cn_nameptr for callers that need the name. Callers needing
* the name set the SAVENAME flag. When done, they assume
* responsibility for freeing the pathname buffer.
*
* At this point, our only vnode state is that "dp" is held and locked.
*/
cnp->cn_consume = 0;
cp = NULL;
cnp->cn_hash = namei_hash(cnp->cn_nameptr, &cp);
cnp->cn_namelen = cp - cnp->cn_nameptr;
if (cnp->cn_namelen > NAME_MAX) {
vput(state->dp);
ndp->ni_dvp = NULL;
return ENAMETOOLONG;
}
#ifdef NAMEI_DIAGNOSTIC
{ char c = *cp;
*(char *)cp = '\0';
printf("{%s}: ", cnp->cn_nameptr);
*(char *)cp = c; }
#endif /* NAMEI_DIAGNOSTIC */
ndp->ni_pathlen -= cnp->cn_namelen;
ndp->ni_next = cp;
/*
* If this component is followed by a slash, then move the pointer to
* the next component forward, and remember that this component must be
* a directory.
*/
if (*cp == '/') {
do {
cp++;
} while (*cp == '/');
state->slashes = cp - ndp->ni_next;
ndp->ni_pathlen -= state->slashes;
ndp->ni_next = cp;
cnp->cn_flags |= REQUIREDIR;
} else {
state->slashes = 0;
cnp->cn_flags &= ~REQUIREDIR;
}
/*
* We do special processing on the last component, whether or not it's
* a directory. Cache all intervening lookups, but not the final one.
*/
if (*cp == '\0') {
if (state->docache)
cnp->cn_flags |= MAKEENTRY;
else
cnp->cn_flags &= ~MAKEENTRY;
cnp->cn_flags |= ISLASTCN;
} else {
cnp->cn_flags |= MAKEENTRY;
cnp->cn_flags &= ~ISLASTCN;
}
if (cnp->cn_namelen == 2 &&
cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
cnp->cn_flags |= ISDOTDOT;
else
cnp->cn_flags &= ~ISDOTDOT;
return 0;
}
static int
lookup_once(struct namei_state *state)
{
struct vnode *tdp; /* saved dp */
struct mount *mp; /* mount table entry */
struct lwp *l = curlwp;
int error;
struct componentname *cnp = state->cnp;
struct nameidata *ndp = state->ndp;
KASSERT(cnp == &ndp->ni_cnd);
/*
* 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.
* 1a. If at the root of the emulation filesystem go to the real
* root. So "/../<path>" is always absolute.
* 1b. If we have somehow gotten out of a jail, warn
* and also ignore it so we can't get farther 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) {
struct proc *p = l->l_proc;
for (;;) {
if (state->dp == ndp->ni_rootdir || state->dp == rootvnode) {
ndp->ni_dvp = state->dp;
ndp->ni_vp = state->dp;
vref(state->dp);
return 0;
}
if (ndp->ni_rootdir != rootvnode) {
int retval;
VOP_UNLOCK(state->dp, 0);
retval = vn_isunder(state->dp, ndp->ni_rootdir, l);
vn_lock(state->dp, LK_EXCLUSIVE | LK_RETRY);
if (!retval) {
/* Oops! We got out of jail! */
log(LOG_WARNING,
"chrooted pid %d uid %d (%s) "
"detected outside of its chroot\n",
p->p_pid, kauth_cred_geteuid(l->l_cred),
p->p_comm);
/* Put us at the jail root. */
vput(state->dp);
state->dp = ndp->ni_rootdir;
ndp->ni_dvp = state->dp;
ndp->ni_vp = state->dp;
vref(state->dp);
vref(state->dp);
vn_lock(state->dp, LK_EXCLUSIVE | LK_RETRY);
return 0;
}
}
if ((state->dp->v_vflag & VV_ROOT) == 0 ||
(cnp->cn_flags & NOCROSSMOUNT))
break;
tdp = state->dp;
state->dp = state->dp->v_mount->mnt_vnodecovered;
vput(tdp);
vref(state->dp);
vn_lock(state->dp, LK_EXCLUSIVE | LK_RETRY);
}
}
/*
* We now have a segment name to search for, and a directory to search.
* Again, our only vnode state is that "dp" is held and locked.
*/
unionlookup:
ndp->ni_dvp = state->dp;
ndp->ni_vp = NULL;
error = VOP_LOOKUP(state->dp, &ndp->ni_vp, cnp);
if (error != 0) {
#ifdef DIAGNOSTIC
if (ndp->ni_vp != NULL)
panic("leaf `%s' should be empty", cnp->cn_nameptr);
#endif /* DIAGNOSTIC */
#ifdef NAMEI_DIAGNOSTIC
printf("not found\n");
#endif /* NAMEI_DIAGNOSTIC */
if ((error == ENOENT) &&
(state->dp->v_vflag & VV_ROOT) &&
(state->dp->v_mount->mnt_flag & MNT_UNION)) {
tdp = state->dp;
state->dp = state->dp->v_mount->mnt_vnodecovered;
vput(tdp);
vref(state->dp);
vn_lock(state->dp, LK_EXCLUSIVE | LK_RETRY);
goto unionlookup;
}
if (error != EJUSTRETURN)
return error;
/*
* If this was not the last component, or there were trailing
* slashes, and we are not going to create a directory,
* then the name must exist.
*/
if ((cnp->cn_flags & (REQUIREDIR | CREATEDIR)) == REQUIREDIR) {
return ENOENT;
}
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (state->rdonly) {
return EROFS;
}
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* (possibly locked) directory vnode in ndp->ni_dvp.
*/
if (cnp->cn_flags & SAVESTART) {
ndp->ni_startdir = ndp->ni_dvp;
vref(ndp->ni_startdir);
}
state->lookup_alldone = 1;
return (0);
}
#ifdef NAMEI_DIAGNOSTIC
printf("found\n");
#endif /* NAMEI_DIAGNOSTIC */
/*
* Take into account any additional components consumed by the
* underlying filesystem. This will include any trailing slashes after
* the last component consumed.
*/
if (cnp->cn_consume > 0) {
ndp->ni_pathlen -= cnp->cn_consume - state->slashes;
ndp->ni_next += cnp->cn_consume - state->slashes;
cnp->cn_consume = 0;
if (ndp->ni_next[0] == '\0')
cnp->cn_flags |= ISLASTCN;
}
state->dp = ndp->ni_vp;
/*
* "state->dp" and "ndp->ni_dvp" are both locked and held,
* and may be the same vnode.
*/
/*
* Check to see if the vnode has been mounted on;
* if so find the root of the mounted file system.
*/
while (state->dp->v_type == VDIR && (mp = state->dp->v_mountedhere) &&
(cnp->cn_flags & NOCROSSMOUNT) == 0) {
error = vfs_busy(mp, NULL);
if (error != 0) {
vput(state->dp);
return error;
}
KASSERT(ndp->ni_dvp != state->dp);
VOP_UNLOCK(ndp->ni_dvp, 0);
vput(state->dp);
error = VFS_ROOT(mp, &tdp);
vfs_unbusy(mp, false, NULL);
if (error) {
vn_lock(ndp->ni_dvp, LK_EXCLUSIVE | LK_RETRY);
return error;
}
VOP_UNLOCK(tdp, 0);
ndp->ni_vp = state->dp = tdp;
vn_lock(ndp->ni_dvp, LK_EXCLUSIVE | LK_RETRY);
vn_lock(ndp->ni_vp, LK_EXCLUSIVE | LK_RETRY);
}
return 0;
}
static int
do_lookup(struct namei_state *state)
{
int error = 0;
struct componentname *cnp = state->cnp;
struct nameidata *ndp = state->ndp;
KASSERT(cnp == &ndp->ni_cnd);
error = lookup_start(state);
if (error) {
goto bad;
}
// XXX: this case should not be necessary given proper handling
// of slashes elsewhere.
if (state->lookup_alldone) {
goto terminal;
}
dirloop:
error = lookup_parsepath(state);
if (error) {
goto bad;
}
error = lookup_once(state);
if (error) {
goto bad;
}
// XXX ought to be able to avoid this case too
if (state->lookup_alldone) {
/* this should NOT be "goto terminal;" */
return 0;
}
/*
* Check for symbolic link. Back up over any slashes that we skipped,
* as we will need them again.
*/
if ((state->dp->v_type == VLNK) && (cnp->cn_flags & (FOLLOW|REQUIREDIR))) {
ndp->ni_pathlen += state->slashes;
ndp->ni_next -= state->slashes;
cnp->cn_flags |= ISSYMLINK;
return (0);
}
/*
* Check for directory, if the component was followed by a series of
* slashes.
*/
if ((state->dp->v_type != VDIR) && (cnp->cn_flags & REQUIREDIR)) {
error = ENOTDIR;
KASSERT(state->dp != ndp->ni_dvp);
vput(state->dp);
goto bad;
}
/*
* Not a symbolic link. If this was not the last component, then
* continue at the next component, else return.
*/
if (!(cnp->cn_flags & ISLASTCN)) {
cnp->cn_nameptr = ndp->ni_next;
if (ndp->ni_dvp == state->dp) {
vrele(ndp->ni_dvp);
} else {
vput(ndp->ni_dvp);
}
goto dirloop;
}
terminal:
if (state->dp == ndp->ni_erootdir) {
/*
* We are about to return the emulation root.
* This isn't a good idea because code might repeatedly
* lookup ".." until the file matches that returned
* for "/" and loop forever.
* So convert it to the real root.
*/
if (ndp->ni_dvp == state->dp)
vrele(state->dp);
else
if (ndp->ni_dvp != NULL)
vput(ndp->ni_dvp);
ndp->ni_dvp = NULL;
vput(state->dp);
state->dp = ndp->ni_rootdir;
vref(state->dp);
vn_lock(state->dp, LK_EXCLUSIVE | LK_RETRY);
ndp->ni_vp = state->dp;
}
/*
* If the caller requested the parent node (i.e.
* it's a CREATE, DELETE, or RENAME), and we don't have one
* (because this is the root directory), then we must fail.
*/
if (ndp->ni_dvp == NULL && cnp->cn_nameiop != LOOKUP) {
switch (cnp->cn_nameiop) {
case CREATE:
error = EEXIST;
break;
case DELETE:
case RENAME:
error = EBUSY;
break;
default:
KASSERT(0);
}
vput(state->dp);
goto bad;
}
/*
* Disallow directory write attempts on read-only lookups.
* Prefers EEXIST over EROFS for the CREATE case.
*/
if (state->rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
if (state->dp != ndp->ni_dvp) {
vput(state->dp);
}
goto bad;
}
if (ndp->ni_dvp != NULL) {
if (cnp->cn_flags & SAVESTART) {
ndp->ni_startdir = ndp->ni_dvp;
vref(ndp->ni_startdir);
}
}
if ((cnp->cn_flags & LOCKLEAF) == 0) {
VOP_UNLOCK(state->dp, 0);
}
return (0);
bad:
ndp->ni_vp = NULL;
return (error);
}
/*
* Externally visible interfaces used by nfsd (bletch, yuk, XXX)
*
* The "index" version differs from the "main" version in that it's
* called from a different place in a different context. For now I
* want to be able to shuffle code in from one call site without
* affecting the other.
*/
int
lookup_for_nfsd(struct nameidata *ndp, struct vnode *dp, int neverfollow)
{
struct namei_state state;
int error;
struct iovec aiov;
struct uio auio;
int linklen;
char *cp;
/* For now at least we don't have to frob the state */
namei_init(&state, ndp);
/*
* BEGIN wodge of code from nfsd
*/
vref(dp);
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
for (;;) {
state.cnp->cn_nameptr = state.cnp->cn_pnbuf;
state.ndp->ni_startdir = dp;
/*
* END wodge of code from nfsd
*/
error = do_lookup(&state);
if (error) {
/* BEGIN from nfsd */
if (ndp->ni_dvp) {
vput(ndp->ni_dvp);
}
PNBUF_PUT(state.cnp->cn_pnbuf);
/* END from nfsd */
namei_cleanup(&state);
return error;
}
/*
* BEGIN wodge of code from nfsd
*/
/*
* Check for encountering a symbolic link
*/
if ((state.cnp->cn_flags & ISSYMLINK) == 0) {
if ((state.cnp->cn_flags & LOCKPARENT) == 0 && state.ndp->ni_dvp) {
if (state.ndp->ni_dvp == state.ndp->ni_vp) {
vrele(state.ndp->ni_dvp);
} else {
vput(state.ndp->ni_dvp);
}
}
if (state.cnp->cn_flags & (SAVENAME | SAVESTART)) {
state.cnp->cn_flags |= HASBUF;
} else {
PNBUF_PUT(state.cnp->cn_pnbuf);
#if defined(DIAGNOSTIC)
state.cnp->cn_pnbuf = NULL;
#endif /* defined(DIAGNOSTIC) */
}
return (0);
} else {
if (neverfollow) {
error = EINVAL;
goto out;
}
if (state.ndp->ni_loopcnt++ >= MAXSYMLINKS) {
error = ELOOP;
goto out;
}
if (state.ndp->ni_vp->v_mount->mnt_flag & MNT_SYMPERM) {
error = VOP_ACCESS(ndp->ni_vp, VEXEC, state.cnp->cn_cred);
if (error != 0)
goto out;
}
if (state.ndp->ni_pathlen > 1)
cp = PNBUF_GET();
else
cp = state.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_resid = MAXPATHLEN;
UIO_SETUP_SYSSPACE(&auio);
error = VOP_READLINK(ndp->ni_vp, &auio, state.cnp->cn_cred);
if (error) {
badlink:
if (ndp->ni_pathlen > 1)
PNBUF_PUT(cp);
goto out;
}
linklen = MAXPATHLEN - auio.uio_resid;
if (linklen == 0) {
error = ENOENT;
goto badlink;
}
if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
error = ENAMETOOLONG;
goto badlink;
}
if (ndp->ni_pathlen > 1) {
memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen);
PNBUF_PUT(state.cnp->cn_pnbuf);
state.cnp->cn_pnbuf = cp;
} else
state.cnp->cn_pnbuf[linklen] = '\0';
state.ndp->ni_pathlen += linklen;
vput(state.ndp->ni_vp);
dp = state.ndp->ni_dvp;
/*
* Check if root directory should replace current directory.
*/
if (state.cnp->cn_pnbuf[0] == '/') {
vput(dp);
dp = ndp->ni_rootdir;
vref(dp);
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
}
}
}
out:
vput(state.ndp->ni_vp);
vput(state.ndp->ni_dvp);
state.ndp->ni_vp = NULL;
PNBUF_PUT(state.cnp->cn_pnbuf);
/*
* END wodge of code from nfsd
*/
namei_cleanup(&state);
return error;
}
int
lookup_for_nfsd_index(struct nameidata *ndp)
{
struct namei_state state;
int error;
/* For now at least we don't have to frob the state */
namei_init(&state, ndp);
error = do_lookup(&state);
namei_cleanup(&state);
return error;
}
/*
* Reacquire a path name component.
* dvp is locked on entry and exit.
* *vpp is locked on exit unless it's NULL.
*/
int
relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
{
int rdonly; /* lookup read-only flag bit */
int error = 0;
#ifdef DEBUG
uint32_t newhash; /* DEBUG: check name hash */
const char *cp; /* DEBUG: check name ptr/len */
#endif /* DEBUG */
/*
* Setup: break out flag bits into variables.
*/
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
/*
* Search a new directory.
*
* The cn_hash value is for use by vfs_cache.
* The last component of the filename is left accessible via
* cnp->cn_nameptr for callers that need the name. Callers needing
* the name set the SAVENAME flag. When done, they assume
* responsibility for freeing the pathname buffer.
*/
#ifdef DEBUG
cp = NULL;
newhash = namei_hash(cnp->cn_nameptr, &cp);
if ((uint32_t)newhash != (uint32_t)cnp->cn_hash)
panic("relookup: bad hash");
if (cnp->cn_namelen != cp - cnp->cn_nameptr)
panic("relookup: bad len");
while (*cp == '/')
cp++;
if (*cp != 0)
panic("relookup: not last component");
#endif /* DEBUG */
/*
* 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')
panic("relookup: null name");
if (cnp->cn_flags & ISDOTDOT)
panic("relookup: lookup on dot-dot");
/*
* We now have a segment name to search for, and a directory to search.
*/
if ((error = VOP_LOOKUP(dvp, vpp, cnp)) != 0) {
#ifdef DIAGNOSTIC
if (*vpp != NULL)
panic("leaf `%s' should be empty", cnp->cn_nameptr);
#endif
if (error != EJUSTRETURN)
goto bad;
}
#ifdef DIAGNOSTIC
/*
* Check for symbolic link
*/
if (*vpp && (*vpp)->v_type == VLNK && (cnp->cn_flags & FOLLOW))
panic("relookup: symlink found");
#endif
/*
* Check for read-only lookups.
*/
if (rdonly && cnp->cn_nameiop != LOOKUP) {
error = EROFS;
if (*vpp) {
vput(*vpp);
}
goto bad;
}
if (cnp->cn_flags & SAVESTART)
vref(dvp);
return (0);
bad:
*vpp = NULL;
return (error);
}
/*
* namei_simple - simple forms of namei.
*
* These are wrappers to allow the simple case callers of namei to be
* left alone while everything else changes under them.
*/
/* Flags */
struct namei_simple_flags_type {
int dummy;
};
static const struct namei_simple_flags_type ns_nn, ns_nt, ns_fn, ns_ft;
const namei_simple_flags_t NSM_NOFOLLOW_NOEMULROOT = &ns_nn;
const namei_simple_flags_t NSM_NOFOLLOW_TRYEMULROOT = &ns_nt;
const namei_simple_flags_t NSM_FOLLOW_NOEMULROOT = &ns_fn;
const namei_simple_flags_t NSM_FOLLOW_TRYEMULROOT = &ns_ft;
static
int
namei_simple_convert_flags(namei_simple_flags_t sflags)
{
if (sflags == NSM_NOFOLLOW_NOEMULROOT)
return NOFOLLOW | 0;
if (sflags == NSM_NOFOLLOW_TRYEMULROOT)
return NOFOLLOW | TRYEMULROOT;
if (sflags == NSM_FOLLOW_NOEMULROOT)
return FOLLOW | 0;
if (sflags == NSM_FOLLOW_TRYEMULROOT)
return FOLLOW | TRYEMULROOT;
panic("namei_simple_convert_flags: bogus sflags\n");
return 0;
}
int
namei_simple_kernel(const char *path, namei_simple_flags_t sflags,
struct vnode **vp_ret)
{
struct nameidata nd;
int err;
NDINIT(&nd,
LOOKUP,
namei_simple_convert_flags(sflags),
UIO_SYSSPACE,
path);
err = namei(&nd);
if (err != 0) {
return err;
}
*vp_ret = nd.ni_vp;
return 0;
}
int
namei_simple_user(const char *path, namei_simple_flags_t sflags,
struct vnode **vp_ret)
{
struct nameidata nd;
int err;
NDINIT(&nd,
LOOKUP,
namei_simple_convert_flags(sflags),
UIO_USERSPACE,
path);
err = namei(&nd);
if (err != 0) {
return err;
}
*vp_ret = nd.ni_vp;
return 0;
}
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