minix/lib/libc/net/nsdispatch.c

693 lines
17 KiB
C
Raw Permalink Normal View History

/* $NetBSD: nsdispatch.c,v 1.37 2012/03/13 21:13:42 christos Exp $ */
/*-
* Copyright (c) 1997, 1998, 1999, 2004 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Luke Mewburn; and by Jason R. Thorpe.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*-
* Copyright (c) 2003 Networks Associates Technology, Inc.
* All rights reserved.
*
* Portions of this software were developed for the FreeBSD Project by
* Jacques A. Vidrine, Safeport Network Services, and Network
* Associates Laboratories, the Security Research Division of Network
* Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
* ("CBOSS"), as part of the DARPA CHATS research program.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: nsdispatch.c,v 1.37 2012/03/13 21:13:42 christos Exp $");
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/queue.h>
#include <assert.h>
#ifdef __ELF__
#include <dlfcn.h>
#endif /* __ELF__ */
#include <err.h>
#include <fcntl.h>
#define _NS_PRIVATE
#include <nsswitch.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "reentrant.h"
extern FILE *_nsyyin;
extern int _nsyyparse(void);
#ifdef __weak_alias
__weak_alias(nsdispatch,_nsdispatch)
#endif
/*
* default sourcelist: `files'
*/
const ns_src __nsdefaultsrc[] = {
{ NSSRC_FILES, NS_SUCCESS },
{ 0, 0 },
};
const ns_src __nsdefaultcompat[] = {
{ NSSRC_COMPAT, NS_SUCCESS },
{ 0, 0 }
};
const ns_src __nsdefaultcompat_forceall[] = {
{ NSSRC_COMPAT, NS_SUCCESS | NS_FORCEALL },
{ 0, 0 }
};
const ns_src __nsdefaultfiles[] = {
{ NSSRC_FILES, NS_SUCCESS },
{ 0, 0 },
};
const ns_src __nsdefaultfiles_forceall[] = {
{ NSSRC_FILES, NS_SUCCESS | NS_FORCEALL },
{ 0, 0 },
};
const ns_src __nsdefaultnis[] = {
{ NSSRC_NIS, NS_SUCCESS },
{ 0, 0 }
};
const ns_src __nsdefaultnis_forceall[] = {
{ NSSRC_NIS, NS_SUCCESS | NS_FORCEALL },
{ 0, 0 }
};
/* Database, source mappings. */
static u_int _nsmapsize;
static ns_dbt *_nsmap;
/* Nsswitch modules. */
static u_int _nsmodsize;
static ns_mod *_nsmod;
/* Placeholder for built-in modules' dlopen() handles. */
static void *_nsbuiltin = &_nsbuiltin;
#ifdef _REENTRANT
/*
* Global nsswitch data structures are mostly read-only, but we update them
* when we read or re-read nsswitch.conf.
*/
static rwlock_t _nslock = RWLOCK_INITIALIZER;
/*
* List of threads currently in nsdispatch(). We use this to detect
* recursive calls and avoid reloading configuration in such cases,
* which could cause deadlock.
*/
struct _ns_drec {
LIST_ENTRY(_ns_drec) list;
thr_t thr;
};
static LIST_HEAD(, _ns_drec) _ns_drec = LIST_HEAD_INITIALIZER(&_ns_drec);
static mutex_t _ns_drec_lock = MUTEX_INITIALIZER;
#endif /* _REENTRANT */
/*
* Runtime determination of whether we are dynamically linked or not.
*/
#ifndef __ELF__
#define is_dynamic() (0) /* don't bother - switch to ELF! */
#else
__weakref_visible int rtld_DYNAMIC __weak_reference(_DYNAMIC);
#define is_dynamic() (&rtld_DYNAMIC != NULL)
#endif
/*
* size of dynamic array chunk for _nsmap and _nsmap[x].srclist (and other
* growing arrays).
*/
#define NSELEMSPERCHUNK 8
/*
* Dynamically growable arrays are used for lists of databases, sources,
* and modules. The following "vector" API is used to isolate the
* common operations.
*/
typedef void (*_nsvect_free_elem)(void *);
static void *
_nsvect_append(const void *elem, void *vec, u_int *count, size_t esize)
{
void *p;
if ((*count % NSELEMSPERCHUNK) == 0) {
p = realloc(vec, (*count + NSELEMSPERCHUNK) * esize);
if (p == NULL)
return (NULL);
vec = p;
}
memmove((void *)(((uintptr_t)vec) + (*count * esize)), elem, esize);
(*count)++;
return (vec);
}
static void *
_nsvect_elem(u_int i, void *vec, u_int count, size_t esize)
{
if (i < count)
return ((void *)((uintptr_t)vec + (i * esize)));
else
return (NULL);
}
static void
_nsvect_free(void *vec, u_int *count, size_t esize, _nsvect_free_elem free_elem)
{
void *elem;
u_int i;
for (i = 0; i < *count; i++) {
elem = _nsvect_elem(i, vec, *count, esize);
if (elem != NULL)
(*free_elem)(elem);
}
if (vec != NULL)
free(vec);
*count = 0;
}
#define _NSVECT_FREE(v, c, s, f) \
do { \
_nsvect_free((v), (c), (s), (f)); \
(v) = NULL; \
} while (/*CONSTCOND*/0)
static int
_nsdbtcmp(const void *a, const void *b)
{
return (strcasecmp(((const ns_dbt *)a)->name,
((const ns_dbt *)b)->name));
}
static int
_nsmodcmp(const void *a, const void *b)
{
return (strcasecmp(((const ns_mod *)a)->name,
((const ns_mod *)b)->name));
}
static int
_nsmtabcmp(const void *a, const void *b)
{
int cmp;
cmp = strcmp(((const ns_mtab *)a)->name,
((const ns_mtab *)b)->name);
if (cmp)
return (cmp);
return (strcasecmp(((const ns_mtab *)a)->database,
((const ns_mtab *)b)->database));
}
static void
_nsmodfree(ns_mod *mod)
{
free(__UNCONST(mod->name));
if (mod->handle == NULL)
return;
if (mod->unregister != NULL)
(*mod->unregister)(mod->mtab, mod->mtabsize);
#ifdef __ELF__
if (mod->handle != _nsbuiltin)
(void) dlclose(mod->handle);
#endif /* __ELF__ */
}
/*
* Load a built-in or dyanamically linked module. If the `reg_fn'
* argument is non-NULL, assume a built-in module and use `reg_fn'
* to register it. Otherwise, search for a dynamic nsswitch module.
*/
static int
_nsloadmod(const char *source, nss_module_register_fn reg_fn)
{
#ifdef __ELF__
char buf[PATH_MAX];
#endif
ns_mod mod, *new;
memset(&mod, 0, sizeof(mod));
mod.name = strdup(source);
if (mod.name == NULL)
return (-1);
if (reg_fn != NULL) {
/*
* The placeholder is required, as a NULL handle
* represents an invalid module.
*/
mod.handle = _nsbuiltin;
} else if (!is_dynamic()) {
goto out;
} else {
#ifdef __ELF__
if (snprintf(buf, sizeof(buf), "nss_%s.so.%d", mod.name,
NSS_MODULE_INTERFACE_VERSION) >= (int)sizeof(buf))
goto out;
mod.handle = dlopen(buf, RTLD_LOCAL | RTLD_LAZY);
if (mod.handle == NULL) {
#ifdef _NSS_DEBUG
/*
* This gets pretty annoying, since the built-in
* sources are not yet modules.
*/
/* XXX log some error? */
#endif
goto out;
}
reg_fn = (nss_module_register_fn) dlsym(mod.handle,
"nss_module_register");
if (reg_fn == NULL) {
(void) dlclose(mod.handle);
mod.handle = NULL;
/* XXX log some error? */
goto out;
}
#else /* ! __ELF__ */
mod.handle = NULL;
#endif /* __ELF__ */
}
mod.mtab = (*reg_fn)(mod.name, &mod.mtabsize, &mod.unregister);
if (mod.mtab == NULL || mod.mtabsize == 0) {
#ifdef __ELF__
if (mod.handle != _nsbuiltin)
(void) dlclose(mod.handle);
#endif /* __ELF__ */
mod.handle = NULL;
/* XXX log some error? */
goto out;
}
if (mod.mtabsize > 1)
qsort(mod.mtab, mod.mtabsize, sizeof(mod.mtab[0]),
_nsmtabcmp);
out:
new = _nsvect_append(&mod, _nsmod, &_nsmodsize, sizeof(*_nsmod));
if (new == NULL) {
_nsmodfree(&mod);
return (-1);
}
_nsmod = new;
/* _nsmodsize already incremented */
qsort(_nsmod, _nsmodsize, sizeof(*_nsmod), _nsmodcmp);
return (0);
}
static void
_nsloadbuiltin(void)
{
/* Do nothing, for now. */
}
int
_nsdbtaddsrc(ns_dbt *dbt, const ns_src *src)
{
void *new;
const ns_mod *mod;
ns_mod modkey;
_DIAGASSERT(dbt != NULL);
_DIAGASSERT(src != NULL);
new = _nsvect_append(src, dbt->srclist, &dbt->srclistsize,
sizeof(*src));
if (new == NULL)
return (-1);
dbt->srclist = new;
/* dbt->srclistsize already incremented */
modkey.name = src->name;
mod = bsearch(&modkey, _nsmod, _nsmodsize, sizeof(*_nsmod), _nsmodcmp);
if (mod == NULL)
return (_nsloadmod(src->name, NULL));
return (0);
}
void
_nsdbtdump(const ns_dbt *dbt)
{
unsigned int i;
_DIAGASSERT(dbt != NULL);
printf("%s (%d source%s):", dbt->name, dbt->srclistsize,
dbt->srclistsize == 1 ? "" : "s");
for (i = 0; i < dbt->srclistsize; i++) {
printf(" %s", dbt->srclist[i].name);
if (!(dbt->srclist[i].flags &
(NS_UNAVAIL|NS_NOTFOUND|NS_TRYAGAIN)) &&
(dbt->srclist[i].flags & NS_SUCCESS))
continue;
printf(" [");
if (!(dbt->srclist[i].flags & NS_SUCCESS))
printf(" SUCCESS=continue");
if (dbt->srclist[i].flags & NS_UNAVAIL)
printf(" UNAVAIL=return");
if (dbt->srclist[i].flags & NS_NOTFOUND)
printf(" NOTFOUND=return");
if (dbt->srclist[i].flags & NS_TRYAGAIN)
printf(" TRYAGAIN=return");
printf(" ]");
}
printf("\n");
}
static void
_nssrclist_free(ns_src **src, u_int srclistsize)
{
u_int i;
for (i = 0; i < srclistsize; i++) {
if ((*src)[i].name != NULL)
free(__UNCONST((*src)[i].name));
}
free(*src);
*src = NULL;
}
static void
_nsdbtfree(ns_dbt *dbt)
{
_nssrclist_free(&dbt->srclist, dbt->srclistsize);
if (dbt->name != NULL)
free(__UNCONST(dbt->name));
}
int
_nsdbtput(const ns_dbt *dbt)
{
ns_dbt *p;
void *new;
u_int i;
_DIAGASSERT(dbt != NULL);
for (i = 0; i < _nsmapsize; i++) {
p = _nsvect_elem(i, _nsmap, _nsmapsize, sizeof(*_nsmap));
if (strcasecmp(dbt->name, p->name) == 0) {
/* overwrite existing entry */
if (p->srclist != NULL)
_nssrclist_free(&p->srclist, p->srclistsize);
memmove(p, dbt, sizeof(*dbt));
return (0);
}
}
new = _nsvect_append(dbt, _nsmap, &_nsmapsize, sizeof(*_nsmap));
if (new == NULL)
return (-1);
_nsmap = new;
/* _nsmapsize already incremented */
return (0);
}
/*
* This function is called each time nsdispatch() is called. If this
* is the first call, or if the configuration has changed, (re-)prepare
* the global data used by NSS.
*/
static int
_nsconfigure(void)
{
#ifdef _REENTRANT
static mutex_t _nsconflock = MUTEX_INITIALIZER;
#endif
static time_t _nsconfmod;
struct stat statbuf;
mutex_lock(&_nsconflock);
if (stat(_PATH_NS_CONF, &statbuf) == -1) {
/*
* No nsswitch.conf; just use whatever configuration we
* currently have, or fall back on the defaults specified
* by the caller.
*/
mutex_unlock(&_nsconflock);
return (0);
}
if (statbuf.st_mtime <= _nsconfmod) {
/* Internal state is up-to-date with nsswitch.conf. */
mutex_unlock(&_nsconflock);
return (0);
}
/*
* Ok, we've decided we need to update the nsswitch configuration
* structures. Acquire a write-lock on _nslock while continuing
* to hold _nsconflock. Acquiring a write-lock blocks while
* waiting for other threads already holding a read-lock to clear.
* We hold _nsconflock for the duration, and update the time stamp
* at the end of the update operation, at which time we release
* both locks.
*/
rwlock_wrlock(&_nslock);
_nsyyin = fopen(_PATH_NS_CONF, "r");
if (_nsyyin == NULL) {
/*
* Unable to open nsswitch.conf; behave as though the
* stat() above failed. Even though we have already
* updated _nsconfmod, if the file reappears, the
* mtime will change.
*/
goto out;
}
_NSVECT_FREE(_nsmap, &_nsmapsize, sizeof(*_nsmap),
(_nsvect_free_elem) _nsdbtfree);
_NSVECT_FREE(_nsmod, &_nsmodsize, sizeof(*_nsmod),
(_nsvect_free_elem) _nsmodfree);
_nsloadbuiltin();
_nsyyparse();
(void) fclose(_nsyyin);
if (_nsmapsize != 0)
qsort(_nsmap, _nsmapsize, sizeof(*_nsmap), _nsdbtcmp);
_nsconfmod = statbuf.st_mtime;
out:
rwlock_unlock(&_nslock);
mutex_unlock(&_nsconflock);
return (0);
}
static nss_method
_nsmethod(const char *source, const char *database, const char *method,
const ns_dtab disp_tab[], void **cb_data)
{
int curdisp;
ns_mod *mod, modkey;
ns_mtab *mtab, mtabkey;
if (disp_tab != NULL) {
for (curdisp = 0; disp_tab[curdisp].src != NULL; curdisp++) {
if (strcasecmp(source, disp_tab[curdisp].src) == 0) {
*cb_data = disp_tab[curdisp].cb_data;
return (disp_tab[curdisp].callback);
}
}
}
modkey.name = source;
mod = bsearch(&modkey, _nsmod, _nsmodsize, sizeof(*_nsmod),
_nsmodcmp);
if (mod != NULL && mod->handle != NULL) {
mtabkey.database = database;
mtabkey.name = method;
mtab = bsearch(&mtabkey, mod->mtab, mod->mtabsize,
sizeof(mod->mtab[0]), _nsmtabcmp);
if (mtab != NULL) {
*cb_data = mtab->mdata;
return (mtab->method);
}
}
*cb_data = NULL;
return (NULL);
}
int
/*ARGSUSED*/
nsdispatch(void *retval, const ns_dtab disp_tab[], const char *database,
const char *method, const ns_src defaults[], ...)
{
static int _nsdispatching;
#ifdef _REENTRANT
struct _ns_drec drec, *ldrec;
#endif
va_list ap;
int i, result;
ns_dbt key;
const ns_dbt *dbt;
const ns_src *srclist;
int srclistsize;
nss_method cb;
void *cb_data;
/* retval may be NULL */
/* disp_tab may be NULL */
_DIAGASSERT(database != NULL);
_DIAGASSERT(method != NULL);
_DIAGASSERT(defaults != NULL);
if (database == NULL || method == NULL || defaults == NULL)
return (NS_UNAVAIL);
/*
* In both the threaded and non-threaded cases, avoid reloading
* the configuration if the current thread is already running
* nsdispatch() (i.e. recursive call).
*
* In the non-threaded case, this avoids changing the data structures
* while we're using them.
*
* In the threaded case, this avoids trying to take a write lock
* while the current thread holds a read lock (which would result
* in deadlock).
*/
#ifdef _REENTRANT
if (__isthreaded) {
drec.thr = thr_self();
mutex_lock(&_ns_drec_lock);
LIST_FOREACH(ldrec, &_ns_drec, list) {
if (ldrec->thr == drec.thr)
break;
}
LIST_INSERT_HEAD(&_ns_drec, &drec, list);
mutex_unlock(&_ns_drec_lock);
if (ldrec == NULL && _nsconfigure()) {
mutex_lock(&_ns_drec_lock);
LIST_REMOVE(&drec, list);
mutex_unlock(&_ns_drec_lock);
return (NS_UNAVAIL);
}
} else
#endif /* _REENTRANT */
if (_nsdispatching++ == 0 && _nsconfigure()) {
_nsdispatching--;
return (NS_UNAVAIL);
}
rwlock_rdlock(&_nslock);
key.name = database;
dbt = bsearch(&key, _nsmap, _nsmapsize, sizeof(*_nsmap), _nsdbtcmp);
if (dbt != NULL) {
srclist = dbt->srclist;
srclistsize = dbt->srclistsize;
} else {
srclist = defaults;
srclistsize = 0;
while (srclist[srclistsize].name != NULL)
srclistsize++;
}
result = 0;
for (i = 0; i < srclistsize; i++) {
cb = _nsmethod(srclist[i].name, database, method,
disp_tab, &cb_data);
result = 0;
if (cb != NULL) {
va_start(ap, defaults);
result = (*cb)(retval, cb_data, ap);
va_end(ap);
if (defaults[0].flags & NS_FORCEALL)
continue;
if (result & srclist[i].flags)
break;
}
}
result &= NS_STATUSMASK; /* clear private flags in result */
rwlock_unlock(&_nslock);
#ifdef _REENTRANT
if (__isthreaded) {
mutex_lock(&_ns_drec_lock);
LIST_REMOVE(&drec, list);
mutex_unlock(&_ns_drec_lock);
} else
#endif /* _REENTRANT */
_nsdispatching--;
return (result ? result : NS_NOTFOUND);
}