/* Copyright (C) CZ.NIC, z.s.p.o. * SPDX-License-Identifier: GPL-3.0-or-later */ #include #include #include "lib/cookies/helper.h" #include "lib/defines.h" /** * @brief Check whether there is a cached cookie that matches the current * client cookie. */ static const uint8_t *peek_and_check_cc(kr_cookie_lru_t *cache, const void *sa, const uint8_t *cc, uint16_t cc_len) { if (kr_fails_assert(cache && sa && cc && cc_len)) return NULL; const uint8_t *cached_opt = kr_cookie_lru_get(cache, sa); if (!cached_opt) return NULL; const uint8_t *cached_cc = knot_edns_opt_get_data((uint8_t *) cached_opt); if (cc_len == KNOT_OPT_COOKIE_CLNT && 0 == memcmp(cc, cached_cc, cc_len)) { return cached_opt; } return NULL; } /** * @brief Put a client cookie into the RR Set. */ static int opt_rr_put_cookie(knot_rrset_t *opt_rr, uint8_t *data, uint16_t data_len, knot_mm_t *mm) { if (kr_fails_assert(opt_rr && data && data_len > 0)) return kr_error(EINVAL); const uint8_t *cc = NULL, *sc = NULL; uint16_t cc_len = 0, sc_len = 0; int ret = knot_edns_opt_cookie_parse(data, data_len, &cc, &cc_len, &sc, &sc_len); if (ret != KNOT_EOK) return kr_error(EINVAL); if (kr_fails_assert(data_len == cc_len + sc_len)) return kr_error(EINVAL); uint16_t cookies_size = data_len; uint8_t *cookies_data = NULL; ret = knot_edns_reserve_unique_option(opt_rr, KNOT_EDNS_OPTION_COOKIE, cookies_size, &cookies_data, mm); if (ret != KNOT_EOK) return kr_error(EINVAL); if (kr_fails_assert(cookies_data)) return kr_error(EINVAL); cookies_size = knot_edns_opt_cookie_write(cc, cc_len, sc, sc_len, cookies_data, cookies_size); if (cookies_size == 0) return kr_error(EINVAL); if (kr_fails_assert(cookies_size == data_len)) return kr_error(EINVAL); return kr_ok(); } /** * @brief Puts entire EDNS option into the RR Set. */ static int opt_rr_put_cookie_opt(knot_rrset_t *opt_rr, uint8_t *option, knot_mm_t *mm) { if (kr_fails_assert(opt_rr && option)) return kr_error(EINVAL); uint16_t opt_code = knot_edns_opt_get_code(option); if (opt_code != KNOT_EDNS_OPTION_COOKIE) return kr_error(EINVAL); uint16_t opt_len = knot_edns_opt_get_length(option); uint8_t *opt_data = knot_edns_opt_get_data(option); if (!opt_data || opt_len == 0) return kr_error(EINVAL); return opt_rr_put_cookie(opt_rr, opt_data, opt_len, mm); } int kr_request_put_cookie(const struct kr_cookie_comp *clnt_comp, kr_cookie_lru_t *cookie_cache, const struct sockaddr *clnt_sa, const struct sockaddr *srvr_sa, struct kr_request *req) { if (!clnt_comp || !req) return kr_error(EINVAL); if (!req->ctx->opt_rr) return kr_ok(); if (!clnt_comp->secr || (clnt_comp->alg_id < 0) || !cookie_cache) return kr_error(EINVAL); /* * Generate client cookie from client address, server address and * secret quantity. */ struct knot_cc_input input = { .clnt_sockaddr = clnt_sa, .srvr_sockaddr = srvr_sa, .secret_data = clnt_comp->secr->data, .secret_len = clnt_comp->secr->size }; uint8_t cc[KNOT_OPT_COOKIE_CLNT]; uint16_t cc_len = KNOT_OPT_COOKIE_CLNT; const struct knot_cc_alg *cc_alg = kr_cc_alg_get(clnt_comp->alg_id); if (!cc_alg) return kr_error(EINVAL); if (kr_fails_assert(cc_alg->gen_func)) return kr_error(EINVAL); cc_len = cc_alg->gen_func(&input, cc, cc_len); if (cc_len != KNOT_OPT_COOKIE_CLNT) return kr_error(EINVAL); const uint8_t *cached_cookie = peek_and_check_cc(cookie_cache, srvr_sa, cc, cc_len); /* Add cookie option. */ int ret; if (cached_cookie) { ret = opt_rr_put_cookie_opt(req->ctx->opt_rr, (uint8_t *)cached_cookie, req->ctx->pool); } else { ret = opt_rr_put_cookie(req->ctx->opt_rr, cc, cc_len, req->ctx->pool); } return ret; } int kr_answer_write_cookie(struct knot_sc_input *sc_input, const struct kr_nonce_input *nonce, const struct knot_sc_alg *alg, knot_pkt_t *pkt) { if (!sc_input || !sc_input->cc || sc_input->cc_len == 0) return kr_error(EINVAL); if (!sc_input->srvr_data || !sc_input->srvr_data->clnt_sockaddr || !sc_input->srvr_data->secret_data || !sc_input->srvr_data->secret_len) { return kr_error(EINVAL); } if (!nonce) return kr_error(EINVAL); if (!alg || !alg->hash_size || !alg->hash_func) return kr_error(EINVAL); if (!pkt || !pkt->opt_rr) return kr_error(EINVAL); uint16_t nonce_len = KR_NONCE_LEN; uint16_t hash_len = alg->hash_size; /* * Space for cookie is reserved inside the EDNS OPT RR of * the answer packet. */ uint8_t *cookie = NULL; uint16_t cookie_len = knot_edns_opt_cookie_data_len(sc_input->cc_len, nonce_len + hash_len); if (cookie_len == 0) return kr_error(EINVAL); int ret = knot_edns_reserve_unique_option(pkt->opt_rr, KNOT_EDNS_OPTION_COOKIE, cookie_len, &cookie, &pkt->mm); if (ret != KNOT_EOK) return kr_error(ENOMEM); if (kr_fails_assert(cookie)) return kr_error(EFAULT); /* * Function knot_edns_opt_cookie_data_len() returns the sum of its * parameters or zero. Anyway, let's check again. */ if (cookie_len < (sc_input->cc_len + nonce_len + hash_len)) return kr_error(EINVAL); /* Copy client cookie data portion. */ memcpy(cookie, sc_input->cc, sc_input->cc_len); if (nonce_len) { /* Write nonce data portion. */ kr_nonce_write_wire(cookie + sc_input->cc_len, nonce_len, nonce); /* Adjust input for written nonce value. */ sc_input->nonce = cookie + sc_input->cc_len; sc_input->nonce_len = nonce_len; } hash_len = alg->hash_func(sc_input, cookie + sc_input->cc_len + nonce_len, hash_len); /* Zero nonce values. */ sc_input->nonce = NULL; sc_input->nonce_len = 0; return (hash_len != 0) ? kr_ok() : kr_error(EINVAL); } int kr_pkt_set_ext_rcode(knot_pkt_t *pkt, uint16_t whole_rcode) { /* * RFC6891 6.1.3 -- extended RCODE forms the upper 8 bits of whole * 12-bit RCODE (together with the 4 bits of 'normal' RCODE). * * | 11 10 09 08 07 06 05 04 | 03 02 01 00 | * | 12-bit whole RCODE | * | 8-bit extended RCODE | 4-bit RCODE | */ if (!pkt || !knot_pkt_has_edns(pkt)) return kr_error(EINVAL); uint8_t rcode = whole_rcode & 0x0f; uint8_t ext_rcode = whole_rcode >> 4; knot_wire_set_rcode(pkt->wire, rcode); knot_edns_set_ext_rcode(pkt->opt_rr, ext_rcode); return kr_ok(); } uint8_t *kr_no_question_cookie_query(const knot_pkt_t *pkt) { if (!pkt || knot_wire_get_qdcount(pkt->wire) > 0) return false; if (knot_wire_get_qr(pkt->wire) != 0 || !pkt->opt_rr) return false; return knot_edns_get_option(pkt->opt_rr, KNOT_EDNS_OPTION_COOKIE); } int kr_parse_cookie_opt(uint8_t *cookie_opt, struct knot_dns_cookies *cookies) { if (!cookie_opt || !cookies) return kr_error(EINVAL); const uint8_t *cookie_data = knot_edns_opt_get_data(cookie_opt); uint16_t cookie_len = knot_edns_opt_get_length(cookie_opt); if (!cookie_data || cookie_len == 0) return kr_error(EINVAL); int ret = knot_edns_opt_cookie_parse(cookie_data, cookie_len, &cookies->cc, &cookies->cc_len, &cookies->sc, &cookies->sc_len); return (ret == KNOT_EOK) ? kr_ok() : kr_error(EINVAL); }