mod_authz_owner.c


/* Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



#include "apr_strings.h"

#include "apr_file_info.h"

#include "apr_user.h"



#include "ap_config.h"

#include "httpd.h"

#include "http_config.h"

#include "http_core.h"

#include "http_log.h"

#include "http_protocol.h"

#include "http_request.h"



#include "mod_auth.h"     /* for AUTHZ_GROUP_NOTE */



typedef struct {

    int authoritative;

} authz_owner_config_rec;



static void *create_authz_owner_dir_config(apr_pool_t *p, char *d)

{

    authz_owner_config_rec *conf = apr_palloc(p, sizeof(*conf));



    conf->authoritative = 1; /* keep the fortress secure by default */

    return conf;

}



static const command_rec authz_owner_cmds[] =

{

    AP_INIT_FLAG("AuthzOwnerAuthoritative", ap_set_flag_slot,

                 (void *)APR_OFFSETOF(authz_owner_config_rec, authoritative),

                 OR_AUTHCFG,

                 "Set to 'Off' to allow access control to be passed along to "

                 "lower modules. (default is On.)"),

    {NULL}

};



module AP_MODULE_DECLARE_DATA authz_owner_module;



static int check_file_owner(request_rec *r)

{

    authz_owner_config_rec *conf = ap_get_module_config(r->per_dir_config,

                                                        &authz_owner_module);

    int m = r->method_number;

    register int x;

    const char *t, *w;

    const apr_array_header_t *reqs_arr = ap_requires(r);

    require_line *reqs;

    int required_owner = 0;

    apr_status_t status = 0;

    char *reason = NULL;



    if (!reqs_arr) {

        return DECLINED;

    }



    reqs = (require_line *)reqs_arr->elts;

    for (x = 0; x < reqs_arr->nelts; x++) {



        /* if authoritative = On then break if a require already failed. */

        if (reason && conf->authoritative) {

            break;

        }



        if (!(reqs[x].method_mask & (AP_METHOD_BIT << m))) {

            continue;

        }



        t = reqs[x].requirement;

        w = ap_getword_white(r->pool, &t);



        if (!strcmp(w, "file-owner")) {

#if !APR_HAS_USER

            if ((required_owner & ~1) && conf->authoritative) {

                break;

            }



            required_owner |= 1; /* remember the requirement */

            reason = "'Require file-owner' is not supported on this platform.";

            continue;

#else  /* APR_HAS_USER */

            char *owner = NULL;

            apr_finfo_t finfo;



            if ((required_owner & ~1) && conf->authoritative) {

                break;

            }



            required_owner |= 1; /* remember the requirement */



            if (!r->filename) {

                reason = "no filename available";

                continue;

            }



            status = apr_stat(&finfo, r->filename, APR_FINFO_USER, r->pool);

            if (status != APR_SUCCESS) {

                reason = apr_pstrcat(r->pool, "could not stat file ",

                                     r->filename, NULL);

                continue;

            }



            if (!(finfo.valid & APR_FINFO_USER)) {

                reason = "no file owner information available";

                continue;

            }



            status = apr_uid_name_get(&owner, finfo.user, r->pool);

            if (status != APR_SUCCESS || !owner) {

                reason = "could not get name of file owner";

                continue;

            }



            if (strcmp(owner, r->user)) {

                reason = apr_psprintf(r->pool, "file owner %s does not match.",

                                      owner);

                continue;

            }



            /* this user is authorized */

            return OK;

#endif /* APR_HAS_USER */

        }



        /* file-group only figures out the file's group and lets

         * other modules do the actual authorization (against a group file/db).

         * Thus, these modules have to hook themselves after

         * mod_authz_owner and of course recognize 'file-group', too.

         */

        if (!strcmp(w, "file-group")) {

#if !APR_HAS_USER

            if ((required_owner & ~6) && conf->authoritative) {

                break;

            }



            required_owner |= 2; /* remember the requirement */

            reason = "'Require file-group' is not supported on this platform.";

            continue;

#else  /* APR_HAS_USER */

            char *group = NULL;

            apr_finfo_t finfo;



            if ((required_owner & ~6) && conf->authoritative) {

                break;

            }



            required_owner |= 2; /* remember the requirement */



            if (!r->filename) {

                reason = "no filename available";

                continue;

            }



            status = apr_stat(&finfo, r->filename, APR_FINFO_GROUP, r->pool);

            if (status != APR_SUCCESS) {

                reason = apr_pstrcat(r->pool, "could not stat file ",

                                     r->filename, NULL);

                continue;

            }



            if (!(finfo.valid & APR_FINFO_GROUP)) {

                reason = "no file group information available";

                continue;

            }



            status = apr_gid_name_get(&group, finfo.group, r->pool);

            if (status != APR_SUCCESS || !group) {

                reason = "could not get name of file group";

                continue;

            }



            /* store group name in a note and let others decide... */

            apr_table_setn(r->notes, AUTHZ_GROUP_NOTE, group);

            required_owner |= 4;

            continue;

#endif /* APR_HAS_USER */

        }

    }



    if (!required_owner || !conf->authoritative) {

        return DECLINED;

    }



    /* allow file-group passed to group db modules either if this is the

     * only applicable requirement here or if a file-owner failed but we're

     * not authoritative.

     * This allows configurations like:

     *

     * AuthzOwnerAuthoritative Off

     * require file-owner

     * require file-group

     *

     * with the semantical meaning of "either owner or group must match"

     * (inclusive or)

     *

     * [ 6 == 2 | 4; 7 == 1 | 2 | 4 ] should I use #defines instead?

     */

    if (required_owner == 6 || (required_owner == 7 && !conf->authoritative)) {

        return DECLINED;

    }



    ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r,

                  "Authorization of user %s to access %s failed, reason: %s",

                  r->user, r->uri, reason ? reason : "unknown");



    ap_note_auth_failure(r);

    return HTTP_UNAUTHORIZED;

}



static void register_hooks(apr_pool_t *p)

{

    ap_hook_auth_checker(check_file_owner, NULL, NULL, APR_HOOK_MIDDLE);

}



module AP_MODULE_DECLARE_DATA authz_owner_module =

{

    STANDARD20_MODULE_STUFF,

    create_authz_owner_dir_config, /* dir config creater */

    NULL,                          /* dir merger --- default is to override */

    NULL,                          /* server config */

    NULL,                          /* merge server config */

    authz_owner_cmds,              /* command apr_table_t */

    register_hooks                 /* register hooks */

};


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