source: trunk/server/source4/heimdal/lib/krb5/plugin.c

/*
 * Copyright (c) 2006 - 2007 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * 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 Institute 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 INSTITUTE 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 INSTITUTE 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 "krb5_locl.h"

#ifdef HAVE_DLFCN_H
#include <dlfcn.h>
#endif
#include <dirent.h>

struct krb5_plugin {
    void *symbol;
    struct krb5_plugin *next;
};

struct plugin {
    enum { DSO, SYMBOL } type;
    union {
        struct {
            char *path;
            void *dsohandle;
        } dso;
        struct {
            enum krb5_plugin_type type;
            char *name;
            char *symbol;
        } symbol;
    } u;
    struct plugin *next;
};

static HEIMDAL_MUTEX plugin_mutex = HEIMDAL_MUTEX_INITIALIZER;
static struct plugin *registered = NULL;
static int plugins_needs_scan = 1;

static const char *sysplugin_dirs[] =  { 
    LIBDIR "/plugin/krb5",
#ifdef __APPLE__
    "/System/Library/KerberosPlugins/KerberosFrameworkPlugins",
#endif
    NULL
};

/*
 *
 */

void *
_krb5_plugin_get_symbol(struct krb5_plugin *p)
{
    return p->symbol;
}

struct krb5_plugin *
_krb5_plugin_get_next(struct krb5_plugin *p)
{
    return p->next;
}

/*
 *
 */

#ifdef HAVE_DLOPEN

static krb5_error_code
loadlib(krb5_context context, char *path)
{
    struct plugin *e;

    e = calloc(1, sizeof(*e));
    if (e == NULL) {
        krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
        free(path);
        return ENOMEM;
    }

#ifndef RTLD_LAZY
#define RTLD_LAZY 0
#endif
#ifndef RTLD_LOCAL
#define RTLD_LOCAL 0
#endif
    e->type = DSO;
    /* ignore error from dlopen, and just keep it as negative cache entry */
    e->u.dso.dsohandle = dlopen(path, RTLD_LOCAL|RTLD_LAZY);
    e->u.dso.path = path;

    e->next = registered;
    registered = e;

    return 0;
}
#endif /* HAVE_DLOPEN */

/**
 * Register a plugin symbol name of specific type.
 * @param context a Keberos context
 * @param type type of plugin symbol
 * @param name name of plugin symbol
 * @param symbol a pointer to the named symbol
 * @return In case of error a non zero error com_err error is returned
 * and the Kerberos error string is set.
 *
 * @ingroup krb5_support
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_plugin_register(krb5_context context,
                     enum krb5_plugin_type type,
                     const char *name,
                     void *symbol)
{
    struct plugin *e;

    HEIMDAL_MUTEX_lock(&plugin_mutex);

    /* check for duplicates */
    for (e = registered; e != NULL; e = e->next) {
        if (e->type == SYMBOL &&
            strcmp(e->u.symbol.name, name) == 0 &&
            e->u.symbol.type == type && e->u.symbol.symbol == symbol) {
            HEIMDAL_MUTEX_unlock(&plugin_mutex);
            return 0;
        }
    }

    e = calloc(1, sizeof(*e));
    if (e == NULL) {
        HEIMDAL_MUTEX_unlock(&plugin_mutex);
        krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
        return ENOMEM;
    }
    e->type = SYMBOL;
    e->u.symbol.type = type;
    e->u.symbol.name = strdup(name);
    if (e->u.symbol.name == NULL) {
        HEIMDAL_MUTEX_unlock(&plugin_mutex);
        free(e);
        krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
        return ENOMEM;
    }
    e->u.symbol.symbol = symbol;

    e->next = registered;
    registered = e;
    HEIMDAL_MUTEX_unlock(&plugin_mutex);

    return 0;
}

static int
is_valid_plugin_filename(const char * n)
{
    if (n[0] == '.' && (n[1] == '\0' || (n[1] == '.' && n[2] == '\0')))
        return 0;

#ifdef _WIN32
    /* On Windows, we only attempt to load .dll files as plug-ins. */
    {
        const char * ext;

        ext = strrchr(n, '.');
        if (ext == NULL)
            return 0;

        return !stricmp(ext, ".dll");
    }
#endif

    return 1;
}

static void
trim_trailing_slash(char * path)
{
    size_t l;

    l = strlen(path);
    while (l > 0 && (path[l - 1] == '/'
#ifdef BACKSLASH_PATH_DELIM
                     || path[l - 1] == '\\'
#endif
               )) {
        path[--l] = '\0';
    }
}

static krb5_error_code
load_plugins(krb5_context context)
{
    struct plugin *e;
    krb5_error_code ret;
    char **dirs = NULL, **di;
    struct dirent *entry;
    char *path;
    DIR *d = NULL;

    if (!plugins_needs_scan)
        return 0;
    plugins_needs_scan = 0;

#ifdef HAVE_DLOPEN

    dirs = krb5_config_get_strings(context, NULL, "libdefaults",
                                   "plugin_dir", NULL);
    if (dirs == NULL)
        dirs = rk_UNCONST(sysplugin_dirs);

    for (di = dirs; *di != NULL; di++) {
        char * dir = *di;

#ifdef KRB5_USE_PATH_TOKENS
        if (_krb5_expand_path_tokens(context, *di, &dir))
            goto next_dir;
#endif

        trim_trailing_slash(dir);

        d = opendir(dir);

        if (d == NULL)
            goto next_dir;

        rk_cloexec_dir(d);

        while ((entry = readdir(d)) != NULL) {
            char *n = entry->d_name;

            /* skip . and .. */
            if (!is_valid_plugin_filename(n))
                continue;

            path = NULL;
            ret = 0;
#ifdef __APPLE__
            { /* support loading bundles on MacOS */
                size_t len = strlen(n);
                if (len > 7 && strcmp(&n[len - 7],  ".bundle") == 0)
                    ret = asprintf(&path, "%s/%s/Contents/MacOS/%.*s", dir, n, (int)(len - 7), n);
            }
#endif
            if (ret < 0 || path == NULL)
                ret = asprintf(&path, "%s/%s", dir, n);

            if (ret < 0 || path == NULL) {
                ret = ENOMEM;
                krb5_set_error_message(context, ret, "malloc: out of memory");
                return ret;
            }

            /* check if already tried */
            for (e = registered; e != NULL; e = e->next)
                if (e->type == DSO && strcmp(e->u.dso.path, path) == 0)
                    break;
            if (e) {
                free(path);
            } else {
                loadlib(context, path); /* store or frees path */
            }
        }
        closedir(d);

    next_dir:
        if (dir != *di)
            free(dir);
    }
    if (dirs != rk_UNCONST(sysplugin_dirs))
        krb5_config_free_strings(dirs);
#endif /* HAVE_DLOPEN */
    return 0;
}

static krb5_error_code
add_symbol(krb5_context context, struct krb5_plugin **list, void *symbol)
{
    struct krb5_plugin *e;
    
    e = calloc(1, sizeof(*e));
    if (e == NULL) {
        krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
        return ENOMEM;
    }
    e->symbol = symbol;
    e->next = *list;
    *list = e;
    return 0;
}

krb5_error_code
_krb5_plugin_find(krb5_context context,
                  enum krb5_plugin_type type,
                  const char *name,
                  struct krb5_plugin **list)
{
    struct plugin *e;
    krb5_error_code ret;

    *list = NULL;

    HEIMDAL_MUTEX_lock(&plugin_mutex);
    
    load_plugins(context);

    for (ret = 0, e = registered; e != NULL; e = e->next) {
        switch(e->type) {
        case DSO: {
            void *sym;
            if (e->u.dso.dsohandle == NULL)
                continue;
            sym = dlsym(e->u.dso.dsohandle, name);
            if (sym)
                ret = add_symbol(context, list, sym);
            break;
        }
        case SYMBOL:
            if (strcmp(e->u.symbol.name, name) == 0 && e->u.symbol.type == type)
                ret = add_symbol(context, list, e->u.symbol.symbol);
            break;
        }
        if (ret) {
            _krb5_plugin_free(*list);
            *list = NULL;
        }
    }

    HEIMDAL_MUTEX_unlock(&plugin_mutex);
    if (ret)
        return ret;

    if (*list == NULL) {
        krb5_set_error_message(context, ENOENT, "Did not find a plugin for %s", name);
        return ENOENT;
    }

    return 0;
}

void
_krb5_plugin_free(struct krb5_plugin *list)
{
    struct krb5_plugin *next;
    while (list) {
        next = list->next;
        free(list);
        list = next;
    }
}
/*
 * module - dict of {
 *      ModuleName = [
 *          plugin = object{ 
 *              array = { ptr, ctx }
 *          }
 *      ]
 * }
 */

static heim_dict_t modules;

struct plugin2 {
    heim_string_t path;
    void *dsohandle;
    heim_dict_t names;
};

static void
plug_dealloc(void *ptr)
{
    struct plugin2 *p = ptr;
    heim_release(p->path);
    heim_release(p->names);
    if (p->dsohandle)
        dlclose(p->dsohandle);
}


void
_krb5_load_plugins(krb5_context context, const char *name, const char **paths)
{
#ifdef HAVE_DLOPEN
    heim_string_t s = heim_string_create(name);
    heim_dict_t module;
    struct dirent *entry;
    krb5_error_code ret;
    const char **di;
    DIR *d;

    HEIMDAL_MUTEX_lock(&plugin_mutex);

    if (modules == NULL) {
        modules = heim_dict_create(11);
        if (modules == NULL) {
            HEIMDAL_MUTEX_unlock(&plugin_mutex);
            return;
        }
    }

    module = heim_dict_copy_value(modules, s);
    if (module == NULL) {
        module = heim_dict_create(11);
        if (module == NULL) {
            HEIMDAL_MUTEX_unlock(&plugin_mutex);
            heim_release(s);
            return;
        }
        heim_dict_add_value(modules, s, module);
    }
    heim_release(s);

    for (di = paths; *di != NULL; di++) {
        d = opendir(*di);
        if (d == NULL)
            continue;
        rk_cloexec_dir(d);

        while ((entry = readdir(d)) != NULL) {
            char *n = entry->d_name;
            char *path = NULL;
            heim_string_t spath;
            struct plugin2 *p;

            /* skip . and .. */
            if (n[0] == '.' && (n[1] == '\0' || (n[1] == '.' && n[2] == '\0')))
                continue;

            ret = 0;
#ifdef __APPLE__
            { /* support loading bundles on MacOS */
                size_t len = strlen(n);
                if (len > 7 && strcmp(&n[len - 7],  ".bundle") == 0)
                    ret = asprintf(&path, "%s/%s/Contents/MacOS/%.*s", *di, n, (int)(len - 7), n);
            }
#endif
            if (ret < 0 || path == NULL)
                ret = asprintf(&path, "%s/%s", *di, n);

            if (ret < 0 || path == NULL)
                continue;

            spath = heim_string_create(n);
            if (spath == NULL) {
                free(path);
                continue;
            }

            /* check if already cached */
            p = heim_dict_copy_value(module, spath);
            if (p == NULL) {
                p = heim_alloc(sizeof(*p), "krb5-plugin", plug_dealloc);
                if (p)
                    p->dsohandle = dlopen(path, RTLD_LOCAL|RTLD_LAZY);

                if (p->dsohandle) {
                    p->path = heim_retain(spath);
                    p->names = heim_dict_create(11);
                    heim_dict_add_value(module, spath, p);
                }
            }
            heim_release(spath);
            heim_release(p);
            free(path);
        }
        closedir(d);
    }
    heim_release(module);
    HEIMDAL_MUTEX_unlock(&plugin_mutex);
#endif /* HAVE_DLOPEN */
}

void
_krb5_unload_plugins(krb5_context context, const char *name)
{
    HEIMDAL_MUTEX_lock(&plugin_mutex);
    heim_release(modules);
    modules = NULL;
    HEIMDAL_MUTEX_unlock(&plugin_mutex);
}

/*
 *
 */

struct common_plugin_method {
    int                 version;
    krb5_error_code     (*init)(krb5_context, void **);
    void                (*fini)(void *);
};

struct plug {
    void *dataptr;
    void *ctx;
};

static void
plug_free(void *ptr)
{
    struct plug *pl = ptr;
    if (pl->dataptr) {
        struct common_plugin_method *cpm = pl->dataptr;
        cpm->fini(pl->ctx);
    }
}

struct iter_ctx {
    krb5_context context;
    heim_string_t n;
    const char *name;
    int min_version;
    heim_array_t result;
    krb5_error_code (*func)(krb5_context, const void *, void *, void *);
    void *userctx;
    krb5_error_code ret;
};

static void
search_modules(void *ctx, heim_object_t key, heim_object_t value)
{
    struct iter_ctx *s = ctx;
    struct plugin2 *p = value;
    struct plug *pl = heim_dict_copy_value(p->names, s->n);
    struct common_plugin_method *cpm;

    if (pl == NULL) {
        if (p->dsohandle == NULL)
            return;

        pl = heim_alloc(sizeof(*pl), "struct-plug", plug_free);
                
        cpm = pl->dataptr = dlsym(p->dsohandle, s->name);
        if (cpm) {
            int ret;

            ret = cpm->init(s->context, &pl->ctx);
            if (ret)
                cpm = pl->dataptr = NULL;
        }
        heim_dict_add_value(p->names, s->n, pl);
    } else {
        cpm = pl->dataptr;
    }
            
    if (cpm && cpm->version >= s->min_version)
        heim_array_append_value(s->result, pl);
    
    heim_release(pl);
}

static void
eval_results(heim_object_t value, void *ctx)
{
    struct plug *pl = value;
    struct iter_ctx *s = ctx;

    if (s->ret != KRB5_PLUGIN_NO_HANDLE)
        return;

    s->ret = s->func(s->context, pl->dataptr, pl->ctx, s->userctx);
}

krb5_error_code
_krb5_plugin_run_f(krb5_context context,
                   const char *module,
                   const char *name,
                   int min_version,
                   int flags,
                   void *userctx,
                   krb5_error_code (*func)(krb5_context, const void *, void *, void *))
{
    heim_string_t m = heim_string_create(module);
    heim_dict_t dict;
    struct iter_ctx s;

    HEIMDAL_MUTEX_lock(&plugin_mutex);

    dict = heim_dict_copy_value(modules, m);
    heim_release(m);
    if (dict == NULL) {
        HEIMDAL_MUTEX_unlock(&plugin_mutex);
        return KRB5_PLUGIN_NO_HANDLE;
    }

    s.context = context;
    s.name = name;
    s.n = heim_string_create(name);
    s.min_version = min_version;
    s.result = heim_array_create();
    s.func = func;
    s.userctx = userctx;

    heim_dict_iterate_f(dict, search_modules, &s);
    
    heim_release(dict);
    
    HEIMDAL_MUTEX_unlock(&plugin_mutex);
    
    s.ret = KRB5_PLUGIN_NO_HANDLE;

    heim_array_iterate_f(s.result, eval_results, &s);

    heim_release(s.result);
    heim_release(s.n);

    return s.ret;
}