res_pjsip_acl.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Mark Michelson <[email protected]>
 *
 * 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",
);