sudo/src/load_plugins.c

/*
 * Copyright (c) 2009-2011 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <config.h>

#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <stdio.h>
#ifdef STDC_HEADERS
# include <stdlib.h>
# include <stddef.h>
#else
# ifdef HAVE_STDLIB_H
#  include <stdlib.h>
# endif
#endif /* STDC_HEADERS */
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#ifdef HAVE_DLOPEN
# include <dlfcn.h>
#else
# include "compat/dlfcn.h"
#endif
#include <errno.h>

#include "sudo.h"
#include "sudo_plugin.h"
#include "sudo_plugin_int.h"
#include "sudo_conf.h"
#include "sudo_debug.h"

#ifndef RTLD_GLOBAL
# define RTLD_GLOBAL	0
#endif

/*
 * Load the plugin specified by "info".
 */
static bool
sudo_load_plugin(struct plugin_container *policy_plugin,
    struct plugin_container_list *io_plugins, struct plugin_info *info)
{
    struct plugin_container *container;
    struct generic_plugin *plugin;
    struct stat sb;
    void *handle;
    char path[PATH_MAX];
    bool rval = false;
    debug_decl(sudo_load_plugin, SUDO_DEBUG_PLUGIN)

    if (info->path[0] == '/') {
	if (strlcpy(path, info->path, sizeof(path)) >= sizeof(path)) {
	    warningx(_("%s: %s"), info->path, strerror(ENAMETOOLONG));
	    goto done;
	}
    } else {
	if (snprintf(path, sizeof(path), "%s%s", _PATH_SUDO_PLUGIN_DIR,
	    info->path) >= sizeof(path)) {
	    warningx(_("%s%s: %s"), _PATH_SUDO_PLUGIN_DIR, info->path,
		strerror(ENAMETOOLONG));
	    goto done;
	}
    }
    if (stat(path, &sb) != 0) {
	warning("%s", path);
	goto done;
    }
    if (sb.st_uid != ROOT_UID) {
	warningx(_("%s must be owned by uid %d"), path, ROOT_UID);
	goto done;
    }
    if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
	warningx(_("%s must be only be writable by owner"), path);
	goto done;
    }

    /* Open plugin and map in symbol */
    handle = dlopen(path, RTLD_LAZY|RTLD_GLOBAL);
    if (!handle) {
	warningx(_("unable to dlopen %s: %s"), path, dlerror());
	goto done;
    }
    plugin = dlsym(handle, info->symbol_name);
    if (!plugin) {
	warningx(_("%s: unable to find symbol %s"), path,
	    info->symbol_name);
	goto done;
    }

    if (plugin->type != SUDO_POLICY_PLUGIN && plugin->type != SUDO_IO_PLUGIN) {
	warningx(_("%s: unknown policy type %d"), path, plugin->type);
	goto done;
    }
    if (SUDO_API_VERSION_GET_MAJOR(plugin->version) != SUDO_API_VERSION_MAJOR) {
	warningx(_("%s: incompatible policy major version %d, expected %d"),
	    path, SUDO_API_VERSION_GET_MAJOR(plugin->version),
	    SUDO_API_VERSION_MAJOR);
	goto done;
    }
    if (plugin->type == SUDO_POLICY_PLUGIN) {
	if (policy_plugin->handle) {
	    warningx(_("%s: only a single policy plugin may be loaded"),
		_PATH_SUDO_CONF);
	    goto done;
	}
	policy_plugin->handle = handle;
	policy_plugin->name = info->symbol_name;
	policy_plugin->options = info->options;
	policy_plugin->u.generic = plugin;
    } else if (plugin->type == SUDO_IO_PLUGIN) {
	container = ecalloc(1, sizeof(*container));
	container->prev = container;
	/* container->next = NULL; */
	container->handle = handle;
	container->name = info->symbol_name;
	container->options = info->options;
	container->u.generic = plugin;
	tq_append(io_plugins, container);
    }

    rval = true;
done:
    debug_return_bool(rval);
}

/*
 * Load the plugins listed in sudo.conf.
 */
bool
sudo_load_plugins(struct plugin_container *policy_plugin,
    struct plugin_container_list *io_plugins)
{
    struct plugin_container *container;
    struct plugin_info_list *plugins;
    struct plugin_info *info;
    bool rval = false;
    debug_decl(sudo_load_plugins, SUDO_DEBUG_PLUGIN)

    /* Walk the plugin list from sudo.conf, if any. */
    plugins = sudo_conf_plugins();
    tq_foreach_fwd(plugins, info) {
	rval = sudo_load_plugin(policy_plugin, io_plugins, info);
	if (!rval)
	    goto done;
    }

    /*
     * If no policy plugin, fall back to the default (sudoers).
     * If there is also no I/O log plugin, sudoers for that too.
     */
    if (policy_plugin->handle == NULL) {
	/* Default policy plugin */
	info = ecalloc(1, sizeof(*info));
	info->symbol_name = "sudoers_policy";
	info->path = SUDOERS_PLUGIN;
	/* info->options = NULL; */
	info->prev = info;
	/* info->next = NULL; */
	rval = sudo_load_plugin(policy_plugin, io_plugins, info);
	efree(info);
	if (!rval)
	    goto done;

	/* Default I/O plugin */
	if (tq_empty(io_plugins)) {
	    info = ecalloc(1, sizeof(*info));
	    info->symbol_name = "sudoers_io";
	    info->path = SUDOERS_PLUGIN;
	    /* info->options = NULL; */
	    info->prev = info;
	    /* info->next = NULL; */
	    rval = sudo_load_plugin(policy_plugin, io_plugins, info);
	    efree(info);
	    if (!rval)
		goto done;
	}
    }
    if (policy_plugin->u.policy->check_policy == NULL) {
	warningx(_("policy plugin %s does not include a check_policy method"),
	    policy_plugin->name);
	rval = false;
	goto done;
    }

    /* Install hooks (XXX - later). */
    if (policy_plugin->u.policy->version >= SUDO_API_MKVERSION(1, 2)) {
	if (policy_plugin->u.policy->register_hooks != NULL)
	    policy_plugin->u.policy->register_hooks(SUDO_HOOK_VERSION, register_hook);
    }
    tq_foreach_fwd(io_plugins, container) {
	if (container->u.io->version >= SUDO_API_MKVERSION(1, 2)) {
	    if (container->u.io->register_hooks != NULL)
		container->u.io->register_hooks(SUDO_HOOK_VERSION, register_hook);
	}
    }

done:
    debug_return_bool(rval);
}