verification_config.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2023, Sangoma Technologies Corporation
 *
 * George Joseph <gjoseph@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.
 */
 
#include "asterisk.h"
 
#include "asterisk/cli.h"
#include "stir_shaken.h"
 
#define CONFIG_TYPE "verification"
 
#define DEFAULT_global_disable 0
 
#define DEFAULT_ca_file NULL
#define DEFAULT_ca_path NULL
#define DEFAULT_crl_file NULL
#define DEFAULT_crl_path NULL
#define DEFAULT_untrusted_cert_file NULL
#define DEFAULT_untrusted_cert_path NULL
static char DEFAULT_cert_cache_dir[PATH_MAX];
 
#define DEFAULT_curl_timeout 2
#define DEFAULT_max_iat_age 15
#define DEFAULT_max_date_header_age 15
#define DEFAULT_max_cache_entry_age 3600
#define DEFAULT_max_cache_size 1000
#define DEFAULT_stir_shaken_failure_action stir_shaken_failure_action_CONTINUE
#define DEFAULT_use_rfc9410_responses use_rfc9410_responses_NO
#define DEFAULT_relax_x5u_port_scheme_restrictions relax_x5u_port_scheme_restrictions_NO
#define DEFAULT_relax_x5u_path_restrictions relax_x5u_path_restrictions_NO
#define DEFAULT_load_system_certs load_system_certs_NO
 
static struct verification_cfg *empty_cfg = NULL;
 
#define STIR_SHAKEN_DIR_NAME "stir_shaken"
 
struct verification_cfg *vs_get_cfg(void)
{
    struct verification_cfg *cfg = ast_sorcery_retrieve_by_id(get_sorcery(),
        CONFIG_TYPE, CONFIG_TYPE);
    if (cfg) {
        return cfg;
    }
 
    return empty_cfg ? ao2_bump(empty_cfg) : NULL;
}
 
int vs_is_config_loaded(void)
{
    struct verification_cfg *cfg = ast_sorcery_retrieve_by_id(get_sorcery(),
        CONFIG_TYPE, CONFIG_TYPE);
    ao2_cleanup(cfg);
 
    return !!cfg;
}
 
generate_vcfg_common_sorcery_handlers(verification_cfg);
 
void vcfg_cleanup(struct verification_cfg_common *vcfg_common)
{
    if (!vcfg_common) {
        return;
    }
    ast_string_field_free_memory(vcfg_common);
    if (vcfg_common->tcs) {
        crypto_free_cert_store(vcfg_common->tcs);
    }
    ast_free_acl_list(vcfg_common->acl);
}
 
static void verification_destructor(void *obj)
{
    struct verification_cfg *cfg = obj;
    ast_string_field_free_memory(cfg);
    vcfg_cleanup(&cfg->vcfg_common);
}
 
static void *verification_alloc(const char *name)
{
    struct verification_cfg *cfg;
 
    cfg = ast_sorcery_generic_alloc(sizeof(*cfg), verification_destructor);
    if (!cfg) {
        return NULL;
    }
 
    if (ast_string_field_init(cfg, 1024)) {
        ao2_ref(cfg, -1);
        return NULL;
    }
 
    /*
     * The memory for vcfg_common actually comes from cfg
     * due to the weirdness of the STRFLDSET macro used with
     * sorcery.  We just use a token amount of memory in
     * this call so the initialize doesn't fail.
     */
    if (ast_string_field_init(&cfg->vcfg_common, 8)) {
        ao2_ref(cfg, -1);
        return NULL;
    }
 
    return cfg;
}
 
int vs_copy_cfg_common(const char *id, struct verification_cfg_common *cfg_dst,
    struct verification_cfg_common *cfg_src)
{
    int rc = 0;
 
    if (!cfg_dst || !cfg_src) {
        return -1;
    }
 
    if (!cfg_dst->tcs && cfg_src->tcs) {
        cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, ca_file);
        cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, ca_path);
        cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, crl_file);
        cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, crl_path);
        cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, untrusted_cert_file);
        cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, untrusted_cert_path);
        ao2_bump(cfg_src->tcs);
        cfg_dst->tcs = cfg_src->tcs;
    }
 
    cfg_sf_copy_wrapper(id, cfg_dst, cfg_src, cert_cache_dir);
 
    cfg_uint_copy(cfg_dst, cfg_src, curl_timeout);
    cfg_uint_copy(cfg_dst, cfg_src, max_iat_age);
    cfg_uint_copy(cfg_dst, cfg_src, max_date_header_age);
    cfg_uint_copy(cfg_dst, cfg_src, max_cache_entry_age);
    cfg_uint_copy(cfg_dst, cfg_src, max_cache_size);
 
    cfg_enum_copy(cfg_dst, cfg_src, stir_shaken_failure_action);
    cfg_enum_copy(cfg_dst, cfg_src, use_rfc9410_responses);
    cfg_enum_copy(cfg_dst, cfg_src, relax_x5u_port_scheme_restrictions);
    cfg_enum_copy(cfg_dst, cfg_src, relax_x5u_path_restrictions);
    cfg_enum_copy(cfg_dst, cfg_src, load_system_certs);
 
    if (cfg_src->acl) {
        ast_free_acl_list(cfg_dst->acl);
        cfg_dst->acl = ast_duplicate_acl_list(cfg_src->acl);
    }
 
    return rc;
}
 
int vs_check_common_config(const char *id,
    struct verification_cfg_common *vcfg_common)
{
    SCOPE_ENTER(3, "%s: Checking common config\n", id);
 
    if (!ast_strlen_zero(vcfg_common->ca_file)
        && !ast_file_is_readable(vcfg_common->ca_file)) {
        SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
            "%s: ca_file '%s' not found, or is unreadable\n",
            id, vcfg_common->ca_file);
    }
 
    if (!ast_strlen_zero(vcfg_common->ca_path)
        && !ast_file_is_readable(vcfg_common->ca_path)) {
        SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
            "%s: ca_path '%s' not found, or is unreadable\n",
            id, vcfg_common->ca_path);
    }
 
    if (!ast_strlen_zero(vcfg_common->crl_file)
        && !ast_file_is_readable(vcfg_common->crl_file)) {
        SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
            "%s: crl_file '%s' not found, or is unreadable\n",
            id, vcfg_common->crl_file);
    }
 
    if (!ast_strlen_zero(vcfg_common->crl_path)
        && !ast_file_is_readable(vcfg_common->crl_path)) {
        SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
            "%s: crl_path '%s' not found, or is unreadable\n",
            id, vcfg_common->crl_path);
    }
 
    if (!ast_strlen_zero(vcfg_common->untrusted_cert_file)
        && !ast_file_is_readable(vcfg_common->untrusted_cert_file)) {
        SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
            "%s: untrusted_cert_file '%s' not found, or is unreadable\n",
            id, vcfg_common->untrusted_cert_file);
    }
 
    if (!ast_strlen_zero(vcfg_common->untrusted_cert_path)
        && !ast_file_is_readable(vcfg_common->untrusted_cert_path)) {
        SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
            "%s: untrusted_cert_path '%s' not found, or is unreadable\n",
            id, vcfg_common->untrusted_cert_path);
    }
 
    if (!ast_strlen_zero(vcfg_common->ca_file)
        || !ast_strlen_zero(vcfg_common->ca_path)) {
        int rc = 0;
 
        if (!vcfg_common->tcs) {
            vcfg_common->tcs = crypto_create_cert_store();
            if (!vcfg_common->tcs) {
                SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                    "%s: Unable to create CA cert store\n", id);
            }
        }
        rc = crypto_load_cert_store(vcfg_common->tcs,
            vcfg_common->ca_file, vcfg_common->ca_path);
        if (rc != 0) {
            SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                "%s: Unable to load CA cert store from '%s' or '%s'\n",
                id, vcfg_common->ca_file, vcfg_common->ca_path);
        }
    }
 
    if (!ast_strlen_zero(vcfg_common->crl_file)
        || !ast_strlen_zero(vcfg_common->crl_path)) {
        int rc = 0;
 
        if (!vcfg_common->tcs) {
            vcfg_common->tcs = crypto_create_cert_store();
            if (!vcfg_common->tcs) {
                SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                    "%s: Unable to create CA cert store\n", id);
            }
        }
        rc = crypto_load_crl_store(vcfg_common->tcs,
            vcfg_common->crl_file, vcfg_common->crl_path);
        if (rc != 0) {
            SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                "%s: Unable to load CA CRL store from '%s' or '%s'\n",
                id, vcfg_common->crl_file, vcfg_common->crl_path);
        }
    }
 
    if (!ast_strlen_zero(vcfg_common->untrusted_cert_file)
        || !ast_strlen_zero(vcfg_common->untrusted_cert_path)) {
        int rc = 0;
 
        if (!vcfg_common->tcs) {
            vcfg_common->tcs = crypto_create_cert_store();
            if (!vcfg_common->tcs) {
                SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                    "%s: Unable to create CA cert store\n", id);
            }
        }
        rc = crypto_load_untrusted_cert_store(vcfg_common->tcs,
            vcfg_common->untrusted_cert_file, vcfg_common->untrusted_cert_path);
        if (rc != 0) {
            SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                "%s: Unable to load CA CRL store from '%s' or '%s'\n",
                id, vcfg_common->untrusted_cert_file, vcfg_common->untrusted_cert_path);
        }
    }
 
    if (vcfg_common->tcs) {
        if (ENUM_BOOL(vcfg_common->load_system_certs, load_system_certs)) {
            X509_STORE_set_default_paths(vcfg_common->tcs->certs);
        }
 
        if (!ast_strlen_zero(vcfg_common->crl_file)
            || !ast_strlen_zero(vcfg_common->crl_path)) {
            X509_STORE_set_flags(vcfg_common->tcs->certs, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_EXTENDED_CRL_SUPPORT);
        }
    }
 
    if (!ast_strlen_zero(vcfg_common->cert_cache_dir)) {
        FILE *fp;
        char *testfile;
 
        if (ast_asprintf(&testfile, "%s/testfile", vcfg_common->cert_cache_dir) <= 0) {
            SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                "%s: Unable to allocate memory for testfile\n", id);
        }
 
        fp = fopen(testfile, "w+");
        if (!fp) {
            ast_free(testfile);
            SCOPE_EXIT_LOG_RTN_VALUE(-1, LOG_ERROR,
                "%s: cert_cache_dir '%s' was not writable\n",
                id, vcfg_common->cert_cache_dir);
        }
        fclose(fp);
        remove(testfile);
        ast_free(testfile);
    }
 
    SCOPE_EXIT_RTN_VALUE(0, "%s: Done\n", id);
}
 
static char *special_addresses[] = {
    "0.0.0.0/8",
    "10.0.0.0/8",
    "100.64.0.0/10",
    "127.0.0.0/8",
    "169.254.0.0/16",
    "172.16.0.0/12",
    "192.0.0.0/24",
    "192.0.0.0/29",
    "192.88.99.0/24",
    "192.168.0.0/16",
    "198.18.0.0/15",
    "198.51.100.0/24",
    "203.0.113.0/24",
    "240.0.0.0/4",
    "255.255.255.255/32",
    "::1/128",
    "::/128",
/*  "64:ff9b::/96", IPv4-IPv6 translation addresses should probably not be blocked by default */
/*  "::ffff:0:0/96", IPv4 mapped addresses should probably not be blocked by default */
    "100::/64",
    "2001::/23",
    "2001::/32",
    "2001:2::/48",
    "2001:db8::/32",
    "2001:10::/28",
/*  "2002::/16", 6to4 should problably not be blocked by default */
    "fc00::/7",
    "fe80::/10",
};
 
static int verification_apply(const struct ast_sorcery *sorcery, void *obj)
{
    struct verification_cfg *cfg = obj;
    const char *id = ast_sorcery_object_get_id(cfg);
 
    if (vs_check_common_config("verification", &cfg->vcfg_common) !=0) {
        return -1;
    }
 
    if (!cfg->vcfg_common.acl) {
        int error = 0;
        int ignore;
        int i;
 
        ast_append_acl("permit", "0.0.0.0/0", &cfg->vcfg_common.acl, &error, &ignore);
        if (error) {
            ast_free_acl_list(cfg->vcfg_common.acl);
            cfg->vcfg_common.acl = NULL;
            ast_log(LOG_ERROR, "%s: Unable to create default acl rule for '%s: %s'\n",
                id, "permit", "0.0.0.0/0");
            return -1;
        }
 
        for (i = 0; i < ARRAY_LEN(special_addresses); i++) {
            ast_append_acl("deny", special_addresses[i], &cfg->vcfg_common.acl, &error, &ignore);
            if (error) {
                ast_free_acl_list(cfg->vcfg_common.acl);
                cfg->vcfg_common.acl = NULL;
                ast_log(LOG_ERROR, "%s: Unable to create default acl rule for '%s: %s'\n",
                    id, "deny", special_addresses[i]);
                return -1;
            }
        }
    }
 
    return 0;
}
 
static char *cli_verification_show(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
    struct verification_cfg *cfg;
    struct config_object_cli_data data = {
        .title = "Default Verification",
        .object_type = config_object_type_verification,
    };
 
    switch(cmd) {
    case CLI_INIT:
        e->command = "stir_shaken show verification";
        e->usage =
            "Usage: stir_shaken show verification\n"
            "       Show the stir/shaken verification settings\n";
        return NULL;
    case CLI_GENERATE:
        return NULL;
    }
 
    if (a->argc != 3) {
        return CLI_SHOWUSAGE;
    }
 
    if (!vs_is_config_loaded()) {
        ast_log(LOG_WARNING,"Stir/Shaken verification service disabled.  Either there were errors in the 'verification' object in stir_shaken.conf or it was missing altogether.\n");
        return CLI_FAILURE;
    }
 
    cfg = vs_get_cfg();
    config_object_cli_show(cfg, a, &data, 0);
 
    ao2_cleanup(cfg);
 
    return CLI_SUCCESS;
}
 
static struct ast_cli_entry verification_cli[] = {
    AST_CLI_DEFINE(cli_verification_show, "Show stir/shaken verification configuration"),
};
 
int vs_config_reload(void)
{
    struct ast_sorcery *sorcery = get_sorcery();
    ast_sorcery_force_reload_object(sorcery, CONFIG_TYPE);
 
    if (!vs_is_config_loaded()) {
        ast_log(LOG_WARNING,"Stir/Shaken verification service disabled.  Either there were errors in the 'verification' object in stir_shaken.conf or it was missing altogether.\n");
    }
    if (!empty_cfg) {
        empty_cfg = verification_alloc(CONFIG_TYPE);
        if (!empty_cfg) {
            return -1;
        }
        empty_cfg->global_disable = 1;
    }
 
    return 0;
}
 
int vs_config_unload(void)
{
    ast_cli_unregister_multiple(verification_cli,
        ARRAY_LEN(verification_cli));
    ao2_cleanup(empty_cfg);
 
    return 0;
}
 
int vs_config_load(void)
{
    struct ast_sorcery *sorcery = get_sorcery();
 
    snprintf(DEFAULT_cert_cache_dir, sizeof(DEFAULT_cert_cache_dir), "%s/keys/%s/cache",
        ast_config_AST_DATA_DIR, STIR_SHAKEN_DIR_NAME);
 
    ast_sorcery_apply_default(sorcery, CONFIG_TYPE, "config",
        "stir_shaken.conf,criteria=type=" CONFIG_TYPE ",single_object=yes,explicit_name=" CONFIG_TYPE);
 
    if (ast_sorcery_object_register(sorcery, CONFIG_TYPE, verification_alloc,
            NULL, verification_apply)) {
        ast_log(LOG_ERROR, "stir/shaken - failed to register '%s' sorcery object\n", CONFIG_TYPE);
        return -1;
    }
 
    ast_sorcery_object_field_register_nodoc(sorcery, CONFIG_TYPE, "type", "",
        OPT_NOOP_T, 0, 0);
 
    ast_sorcery_object_field_register(sorcery, CONFIG_TYPE, "global_disable",
        DEFAULT_global_disable ? "yes" : "no",
        OPT_YESNO_T, 1, FLDSET(struct verification_cfg, global_disable));
 
    register_common_verification_fields(sorcery, verification_cfg, CONFIG_TYPE,);
 
    ast_sorcery_load_object(sorcery, CONFIG_TYPE);
 
    if (!vs_is_config_loaded()) {
        ast_log(LOG_WARNING,"Stir/Shaken verification service disabled.  Either there were errors in the 'verification' object in stir_shaken.conf or it was missing altogether.\n");
    }
    if (!empty_cfg) {
        empty_cfg = verification_alloc(CONFIG_TYPE);
        if (!empty_cfg) {
            return -1;
        }
        empty_cfg->global_disable = 1;
    }
 
    ast_cli_register_multiple(verification_cli,
        ARRAY_LEN(verification_cli));
 
    return 0;
}