res_pjsip_acl.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Mark Michelson <mmichelson@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*** MODULEINFO
    <depend>pjproject</depend>
    <depend>res_pjsip</depend>
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include <pjsip.h>
 
#include "asterisk/res_pjsip.h"
#include "asterisk/module.h"
#include "asterisk/logger.h"
#include "asterisk/sorcery.h"
#include "asterisk/acl.h"
#include "asterisk/stasis.h"
#include "asterisk/security_events.h"
 
/*** DOCUMENTATION
    <configInfo name="res_pjsip_acl" language="en_US">
        <synopsis>SIP ACL module</synopsis>
        <description><para>
            <emphasis>ACL</emphasis>
            </para><para>
            The ACL module used by <literal>res_pjsip</literal>. This module is
            independent of <literal>endpoints</literal> and operates on all inbound
            SIP communication using res_pjsip.
            </para><para>
            There are two main ways of defining your ACL with the options
            provided. You can use the <literal>permit</literal> and <literal>deny</literal> options
            which act on <emphasis>IP</emphasis> addresses, or the <literal>contactpermit</literal>
            and <literal>contactdeny</literal> options which act on <emphasis>Contact header</emphasis>
            addresses in incoming REGISTER requests. You can combine the various options to
            create a mixed ACL.
            </para><para>
            Additionally, instead of defining an ACL with options, you can reference IP or
            Contact header ACLs from the file <filename>acl.conf</filename> by using the <literal>acl</literal>
            or <literal>contactacl</literal> options.
        </para></description>
        <configFile name="pjsip.conf">
            <configObject name="acl">
                <synopsis>Access Control List</synopsis>
                <configOption name="acl">
                    <synopsis>List of IP ACL section names in acl.conf</synopsis>
                    <description><para>
                        This matches sections configured in <literal>acl.conf</literal>. The value is
                        defined as a list of comma-delimited section names.
                    </para></description>
                </configOption>
                <configOption name="contact_acl">
                    <synopsis>List of Contact ACL section names in acl.conf</synopsis>
                    <description><para>
                        This matches sections configured in <literal>acl.conf</literal>. The value is
                        defined as a list of comma-delimited section names.
                    </para></description>
                </configOption>
                <configOption name="contact_deny">
                    <synopsis>List of Contact header addresses to deny</synopsis>
                    <description><para>
                        The value is a comma-delimited list of IP addresses. IP addresses may
                        have a subnet mask appended. The subnet mask may be written in either
                        CIDR or dotted-decimal notation. Separate the IP address and subnet
                        mask with a slash ('/')
                    </para></description>
                </configOption>
                <configOption name="contact_permit">
                    <synopsis>List of Contact header addresses to permit</synopsis>
                    <description><para>
                        The value is a comma-delimited list of IP addresses. IP addresses may
                        have a subnet mask appended. The subnet mask may be written in either
                        CIDR or dotted-decimal notation. Separate the IP address and subnet
                        mask with a slash ('/')
                    </para></description>
                </configOption>
                <configOption name="deny">
                    <synopsis>List of IP addresses to deny access from</synopsis>
                    <description><para>
                        The value is a comma-delimited list of IP addresses. IP addresses may
                        have a subnet mask appended. The subnet mask may be written in either
                        CIDR or dotted-decimal notation. Separate the IP address and subnet
                        mask with a slash ('/')
                    </para></description>
                </configOption>
                <configOption name="permit">
                    <synopsis>List of IP addresses to permit access from</synopsis>
                    <description><para>
                        The value is a comma-delimited list of IP addresses. IP addresses may
                        have a subnet mask appended. The subnet mask may be written in either
                        CIDR or dotted-decimal notation. Separate the IP address and subnet
                        mask with a slash ('/')
                    </para></description>
                </configOption>
                <configOption name="type">
                    <synopsis>Must be of type 'acl'.</synopsis>
                </configOption>
            </configObject>
        </configFile>
    </configInfo>
 ***/
 
static struct stasis_subscription *acl_change_sub;
 
static int apply_acl(pjsip_rx_data *rdata, struct ast_acl_list *acl)
{
    struct ast_sockaddr addr;
 
    if (ast_acl_list_is_empty(acl)) {
        return 0;
    }
 
    memset(&addr, 0, sizeof(addr));
    ast_sockaddr_parse(&addr, rdata->pkt_info.src_name, PARSE_PORT_FORBID);
    ast_sockaddr_set_port(&addr, rdata->pkt_info.src_port);
 
    if (ast_apply_acl(acl, &addr, "SIP ACL: ") != AST_SENSE_ALLOW) {
        ast_log(LOG_WARNING, "Incoming SIP message from %s did not pass ACL test\n", ast_sockaddr_stringify(&addr));
        return 1;
    }
    return 0;
}
 
static int extract_contact_addr(pjsip_contact_hdr *contact, struct ast_sockaddr **addrs)
{
    pjsip_sip_uri *sip_uri;
    char host[256];
 
    if (!contact || contact->star) {
        *addrs = NULL;
        return 0;
    }
    if (!PJSIP_URI_SCHEME_IS_SIP(contact->uri) && !PJSIP_URI_SCHEME_IS_SIPS(contact->uri)) {
        *addrs = NULL;
        return 0;
    }
    sip_uri = pjsip_uri_get_uri(contact->uri);
    ast_copy_pj_str(host, &sip_uri->host, sizeof(host));
    return ast_sockaddr_resolve(addrs, host, PARSE_PORT_FORBID, AST_AF_UNSPEC);
}
 
static int apply_contact_acl(pjsip_rx_data *rdata, struct ast_acl_list *contact_acl)
{
    int num_contact_addrs;
    int forbidden = 0;
    struct ast_sockaddr *contact_addrs;
    int i;
    pjsip_contact_hdr *contact = (pjsip_contact_hdr *)&rdata->msg_info.msg->hdr;
 
    if (ast_acl_list_is_empty(contact_acl)) {
        return 0;
    }
 
    while ((contact = pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_CONTACT, contact->next))) {
        num_contact_addrs = extract_contact_addr(contact, &contact_addrs);
        if (num_contact_addrs <= 0) {
            continue;
        }
        for (i = 0; i < num_contact_addrs; ++i) {
            if (ast_apply_acl(contact_acl, &contact_addrs[i], "SIP Contact ACL: ") != AST_SENSE_ALLOW) {
                ast_log(LOG_WARNING, "Incoming SIP message from %s did not pass ACL test\n", ast_sockaddr_stringify(&contact_addrs[i]));
                forbidden = 1;
                break;
            }
        }
        ast_free(contact_addrs);
        if (forbidden) {
            /* No use checking other contacts if we already have failed ACL check */
            break;
        }
    }
 
    return forbidden;
}
 
#define SIP_SORCERY_ACL_TYPE "acl"
 
/*!
 * \brief SIP ACL details and configuration.
 */
struct ast_sip_acl {
    SORCERY_OBJECT(details);
    struct ast_acl_list *acl;
    struct ast_acl_list *contact_acl;
};
 
static int check_acls(void *obj, void *arg, int flags)
{
    struct ast_sip_acl *sip_acl = obj;
    pjsip_rx_data *rdata = arg;
 
    if (apply_acl(rdata, sip_acl->acl) ||
        apply_contact_acl(rdata, sip_acl->contact_acl)) {
        return CMP_MATCH | CMP_STOP;
    }
    return 0;
}
 
static pj_bool_t acl_on_rx_msg(pjsip_rx_data *rdata)
{
    RAII_VAR(struct ao2_container *, acls, ast_sorcery_retrieve_by_fields(
             ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE,
             AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL), ao2_cleanup);
    RAII_VAR(struct ast_sip_acl *, matched_acl, NULL, ao2_cleanup);
 
    if (!acls) {
        ast_log(LOG_ERROR, "Unable to retrieve ACL sorcery data\n");
        return PJ_FALSE;
    }
 
    if ((matched_acl = ao2_callback(acls, 0, check_acls, rdata))) {
        if (rdata->msg_info.msg->line.req.method.id != PJSIP_ACK_METHOD) {
            pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 403, NULL, NULL, NULL);
        }
        return PJ_TRUE;
    }
 
    return PJ_FALSE;
}
 
static int acl_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
{
    struct ast_sip_acl *sip_acl = obj;
    int error = 0;
    int ignore;
 
    if (!strncmp(var->name, "contact_", 8)) {
        ast_append_acl(var->name + 8, var->value, &sip_acl->contact_acl, &error, &ignore);
        if (error) {
            ast_log(LOG_ERROR, "Bad contact ACL '%s' at line '%d' of pjsip.conf\n",
                    var->value, var->lineno);
        }
    } else {
        ast_append_acl(var->name, var->value, &sip_acl->acl, &error, &ignore);
        if (error) {
            ast_log(LOG_ERROR, "Bad ACL '%s' at line '%d' of pjsip.conf\n",
                    var->value, var->lineno);
        }
    }
 
    if (error) {
        ast_log(LOG_ERROR, "There is an error in ACL configuration. Blocking ALL SIP traffic.\n");
        ast_append_acl("deny", "0.0.0.0/0.0.0.0", &sip_acl->acl, NULL, &ignore);
    }
 
    return error;
}
 
static pjsip_module acl_module = {
    .name = { "ACL Module", 14 },
    /* This should run after a logger but before anything else */
    .priority = 1,
    .on_rx_request = acl_on_rx_msg,
};
 
static void acl_destroy(void *obj)
{
    struct ast_sip_acl *sip_acl = obj;
    sip_acl->acl = ast_free_acl_list(sip_acl->acl);
    sip_acl->contact_acl = ast_free_acl_list(sip_acl->contact_acl);
}
 
static void *acl_alloc(const char *name)
{
    struct ast_sip_acl *sip_acl =
        ast_sorcery_generic_alloc(sizeof(*sip_acl), acl_destroy);
 
    return sip_acl;
}
 
static void acl_change_stasis_cb(void *data, struct stasis_subscription *sub,
    struct stasis_message *message)
{
    if (stasis_message_type(message) != ast_named_acl_change_type()) {
        return;
    }
 
    ast_sorcery_force_reload_object(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE);
}
 
static int load_module(void)
{
    ast_sorcery_apply_config(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE);
    ast_sorcery_apply_default(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE,
                  "config", "pjsip.conf,criteria=type=acl");
 
    if (ast_sorcery_object_register(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE,
                    acl_alloc, NULL, NULL)) {
 
        ast_log(LOG_ERROR, "Failed to register SIP %s object with sorcery\n",
            SIP_SORCERY_ACL_TYPE);
        return AST_MODULE_LOAD_DECLINE;
    }
 
    ast_sorcery_object_field_register(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "type", "", OPT_NOOP_T, 0, 0);
    ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "permit", "", acl_handler, NULL, NULL, 0, 0);
    ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "deny", "", acl_handler, NULL, NULL, 0, 0);
    ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "acl", "", acl_handler, NULL, NULL, 0, 0);
    ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "contact_permit", "", acl_handler, NULL, NULL, 0, 0);
    ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "contact_deny", "", acl_handler, NULL, NULL, 0, 0);
    ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE, "contact_acl", "", acl_handler, NULL, NULL, 0, 0);
 
    ast_sorcery_load_object(ast_sip_get_sorcery(), SIP_SORCERY_ACL_TYPE);
 
    acl_change_sub = stasis_subscribe(ast_security_topic(), acl_change_stasis_cb, NULL);
    stasis_subscription_accept_message_type(acl_change_sub, ast_named_acl_change_type());
    stasis_subscription_set_filter(acl_change_sub, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);
 
    ast_sip_register_service(&acl_module);
 
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    acl_change_sub = stasis_unsubscribe_and_join(acl_change_sub);
    ast_sip_unregister_service(&acl_module);
    return 0;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP ACL Resource",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_APP_DEPEND,
    .requires = "res_pjsip",
);