source: openpam/trunk/lib/openpam_load.c @ 63

/*-
 * Copyright (c) 2002 Networks Associates Technologies, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by ThinkSec AS and
 * NAI Labs, 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.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * 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.
 *
 * $Id$
 */

#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>

#include <security/pam_appl.h>

#include "openpam_impl.h"

#ifdef OPENPAM_STATIC_MODULES
SET_DECLARE(_openpam_modules, pam_module_t);
#endif

const char *_pam_sm_func_name[PAM_NUM_PRIMITIVES] = {
        "pam_sm_authenticate",
        "pam_sm_setcred",
        "pam_sm_acct_mgmt",
        "pam_sm_open_session",
        "pam_sm_close_session",
        "pam_sm_chauthtok"
};

static pam_module_t *modules;

/*
 * Load a dynamic module, or locate a static one.  Keep a list of
 * previously found modules to speed up the process.
 */

static pam_module_t *
openpam_load_module(const char *path)
{
        pam_module_t *module;
        void *dlh;
        int i;

        /* check cache first */
        for (module = modules; module != NULL; module = module->next)
                if (strcmp(module->path, path) == 0)
                        goto found;

        /* nope; try to load */
        if ((dlh = dlopen(path, RTLD_NOW)) == NULL) {
                openpam_log(PAM_LOG_ERROR, "dlopen(): %s", dlerror());
        } else {
                if ((module = calloc(1, sizeof *module)) == NULL)
                        goto buf_err;
                if ((module->path = strdup(path)) == NULL)
                        goto buf_err;
                module->dlh = dlh;
                for (i = 0; i < PAM_NUM_PRIMITIVES; ++i)
                        module->func[i] = dlsym(dlh, _pam_sm_func_name[i]);
        }
        openpam_log(PAM_LOG_DEBUG, "%s dynamic %s",
            (module == NULL) ? "no" : "using", path);

#ifdef OPENPAM_STATIC_MODULES
        /* look for a static module */
        if (module == NULL && strchr(path, '/') == NULL) {
                pam_module_t **modp;
                
                SET_FOREACH(modp, _openpam_modules) {
                        if (strcmp((*modp)->path, path) == 0) {
                                module = *modp;
                                break;
                        }
                }
                openpam_log(PAM_LOG_DEBUG, "%s static %s",
                    (module == NULL) ? "no" : "using", path);
        }
#endif
        if (module == NULL)
                return (NULL);
        module->next = modules;
        module->prev = NULL;
        modules = module;
 found:
        ++module->refcount;
        return (module);
 buf_err:
        openpam_log(PAM_LOG_ERROR, "malloc(): %m");
        dlclose(dlh);
        free(module);
        return (NULL);
}


/*
 * Release a module.
 * XXX highly thread-unsafe
 */

static void
openpam_release_module(pam_module_t *module)
{
        if (module == NULL)
                return;
        --module->refcount;
        if (module->refcount > 0)
                /* still in use */
                return;
        if (module->refcount < 0) {
                openpam_log(PAM_LOG_ERROR, "module %s has negative refcount",
                    module->path);
                module->refcount = 0;
        }
        if (module->dlh == NULL)
                /* static module */
                return;
        dlclose(module->dlh);
        if (module->prev != NULL)
                module->prev->next = module->next;
        if (module->next != NULL)
                module->next->prev = module->prev;
        free(module);
}


/*
 * Destroy a chain, freeing all its links and releasing the modules
 * they point to.
 */

static void
openpam_destroy_chain(pam_chain_t *chain)
{
        if (chain == NULL)
                return;
        openpam_destroy_chain(chain->next);
        chain->next = NULL;
        while (chain->optc--)
                free(chain->optv[chain->optc]);
        free(chain->optv);
        openpam_release_module(chain->module);
        free(chain);
}

/*
 * Add a module to a chain.
 */

int
openpam_add_module(pam_handle_t *pamh,
        int chain,
        int flag,
        const char *modpath,
        int optc,
        const char *optv[])
{
        pam_chain_t *new, *iterator;

        if ((new = calloc(1, sizeof *new)) == NULL)
                goto buf_err;
        if ((new->optv = malloc(sizeof(char *) * (optc + 1))) == NULL)
                goto buf_err;
        while (optc--)
                if ((new->optv[new->optc++] = strdup(*optv++)) == NULL)
                        goto buf_err;
        new->optv[new->optc] = NULL;
        new->flag = flag;
        if ((new->module = openpam_load_module(modpath)) == NULL) {
                openpam_destroy_chain(new);
                return (PAM_OPEN_ERR);
        }
        if ((iterator = pamh->chains[chain]) != NULL) {
                while (iterator->next != NULL)
                        iterator = iterator->next;
                iterator->next = new;
        } else {
                pamh->chains[chain] = new;
        }
        return (PAM_SUCCESS);

 buf_err:
        openpam_log(PAM_LOG_ERROR, "%m");
        openpam_destroy_chain(new);
        return (PAM_BUF_ERR);
}


/*
 * Clear the chains and release the modules
 */

void
openpam_clear_chains(pam_handle_t *pamh)
{
        int i;

        for (i = 0; i < PAM_NUM_CHAINS; ++i)
                openpam_destroy_chain(pamh->chains[i]);
}

/*
 * NOPARSE
 */