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-rw-r--r--src/irmd/oap/srv.c462
1 files changed, 462 insertions, 0 deletions
diff --git a/src/irmd/oap/srv.c b/src/irmd/oap/srv.c
new file mode 100644
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--- /dev/null
+++ b/src/irmd/oap/srv.c
@@ -0,0 +1,462 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2024
+ *
+ * OAP - Server-side processing
+ *
+ * Dimitri Staessens <dimitri@ouroboros.rocks>
+ * Sander Vrijders <sander@ouroboros.rocks>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#if defined(__linux__) || defined(__CYGWIN__)
+ #define _DEFAULT_SOURCE
+#else
+ #define _POSIX_C_SOURCE 200809L
+#endif
+
+#define OUROBOROS_PREFIX "irmd/oap"
+
+#include <ouroboros/crypt.h>
+#include <ouroboros/errno.h>
+#include <ouroboros/logs.h>
+
+#include "config.h"
+
+#include "auth.h"
+#include "hdr.h"
+#include "io.h"
+#include "oap.h"
+
+#include <assert.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef OAP_TEST_MODE
+extern int load_srv_credentials(const struct name_info * info,
+ void ** pkp,
+ void ** crt);
+extern int load_srv_kex_config(const struct name_info * info,
+ struct sec_config * cfg);
+extern int load_server_kem_keypair(const char * name,
+ bool raw_fmt,
+ void ** pkp);
+#else
+
+int load_srv_credentials(const struct name_info * info,
+ void ** pkp,
+ void ** crt)
+{
+ assert(info != NULL);
+ assert(pkp != NULL);
+ assert(crt != NULL);
+
+ return load_credentials(info->name, &info->s, pkp, crt);
+}
+
+int load_srv_kex_config(const struct name_info * info,
+ struct sec_config * cfg)
+{
+ assert(info != NULL);
+ assert(cfg != NULL);
+
+ return load_kex_config(info->name, info->s.enc, cfg);
+}
+
+int load_server_kem_keypair(const char * name,
+ bool raw_fmt,
+ void ** pkp)
+{
+ char path[PATH_MAX];
+ const char * ext;
+
+ assert(name != NULL);
+ assert(pkp != NULL);
+
+ ext = raw_fmt ? "raw" : "pem";
+
+ snprintf(path, sizeof(path),
+ OUROBOROS_SRV_CRT_DIR "/%s/kex.key.%s", name, ext);
+
+ if (raw_fmt) {
+ if (crypt_load_privkey_raw_file(path, pkp) < 0) {
+ log_err("Failed to load %s keypair from %s.",
+ ext, path);
+ return -ECRYPT;
+ }
+ } else {
+ if (crypt_load_privkey_file(path, pkp) < 0) {
+ log_err("Failed to load %s keypair from %s.",
+ ext, path);
+ return -ECRYPT;
+ }
+ }
+
+ log_dbg("Loaded server KEM keypair from %s.", path);
+ return 0;
+}
+
+#endif /* OAP_TEST_MODE */
+
+static int get_algo_from_peer_key(const struct oap_hdr * peer_hdr,
+ char * algo_buf)
+{
+ uint8_t * id = peer_hdr->id.data;
+ int ret;
+
+ if (OAP_KEX_IS_RAW_FMT(peer_hdr)) {
+ ret = kex_get_algo_from_pk_raw(peer_hdr->kex, algo_buf);
+ if (ret < 0) {
+ log_err_id(id, "Failed to get algo from raw key.");
+ return -ECRYPT;
+ }
+ } else {
+ ret = kex_get_algo_from_pk_der(peer_hdr->kex, algo_buf);
+ if (ret < 0) {
+ log_err_id(id, "Failed to get algo from DER key.");
+ return -ECRYPT;
+ }
+ }
+
+ return 0;
+}
+
+static int negotiate_kex(const struct oap_hdr * peer_hdr,
+ struct sec_config * kcfg)
+{
+ uint8_t * id = peer_hdr->id.data;
+
+ if (kcfg->c.nid == NID_undef) {
+ if (peer_hdr->cipher_str != NULL) {
+ SET_KEX_CIPHER(kcfg, peer_hdr->cipher_str);
+ if (kcfg->c.nid == NID_undef) {
+ log_err_id(id, "Unsupported cipher '%s'.",
+ peer_hdr->cipher_str);
+ return -ENOTSUP;
+ }
+ log_dbg_id(id, "Peer requested cipher %s.",
+ peer_hdr->cipher_str);
+ } else {
+ log_err_id(id, "Encryption requested, no cipher.");
+ return -ECRYPT;
+ }
+ } else {
+ log_dbg_id(id, "Using local cipher %s.", kcfg->c.str);
+ }
+
+ /* Negotiate KDF - server overrides client if configured */
+ if (kcfg->k.nid != NID_undef) {
+ log_dbg_id(id, "Using local KDF %s.",
+ md_nid_to_str(kcfg->k.nid));
+ } else if (peer_hdr->kdf_nid != NID_undef) {
+ if (md_validate_nid(peer_hdr->kdf_nid) == 0) {
+ kcfg->k.nid = peer_hdr->kdf_nid;
+ log_dbg_id(id, "Using peer KDF %s.",
+ md_nid_to_str(peer_hdr->kdf_nid));
+ } else {
+ log_err_id(id, "Unsupported KDF NID %d.",
+ peer_hdr->kdf_nid);
+ return -ENOTSUP;
+ }
+ }
+
+ if (IS_KEX_ALGO_SET(kcfg))
+ log_info_id(id, "Negotiated %s + %s.",
+ kcfg->x.str, kcfg->c.str);
+ else
+ log_info_id(id, "No key exchange.");
+
+ return 0;
+}
+
+static int do_server_kem_decap(const struct name_info * info,
+ const struct oap_hdr * peer_hdr,
+ struct sec_config * kcfg,
+ struct crypt_sk * sk)
+{
+ buffer_t ct;
+ void * server_pkp = NULL;
+ int ret;
+ uint8_t * id = peer_hdr->id.data;
+
+ ret = load_server_kem_keypair(info->name,
+ peer_hdr->kex_flags.fmt,
+ &server_pkp);
+ if (ret < 0)
+ return ret;
+
+ ct.data = peer_hdr->kex.data;
+ ct.len = peer_hdr->kex.len;
+
+ ret = kex_kem_decap(server_pkp, ct, kcfg->k.nid, sk->key);
+
+ crypt_free_key(server_pkp);
+
+ if (ret < 0) {
+ log_err_id(id, "Failed to decapsulate KEM.");
+ return -ECRYPT;
+ }
+
+ log_dbg_id(id, "Client encaps: decapsulated CT.");
+
+ return 0;
+}
+
+static int do_server_kem_encap(const struct oap_hdr * peer_hdr,
+ struct sec_config * kcfg,
+ buffer_t * kex,
+ struct crypt_sk * sk)
+{
+ buffer_t client_pk;
+ ssize_t ct_len;
+ uint8_t * id = peer_hdr->id.data;
+
+ client_pk.data = peer_hdr->kex.data;
+ client_pk.len = peer_hdr->kex.len;
+
+ if (IS_HYBRID_KEM(kcfg->x.str))
+ ct_len = kex_kem_encap_raw(client_pk, kex->data,
+ kcfg->k.nid, sk->key);
+ else
+ ct_len = kex_kem_encap(client_pk, kex->data,
+ kcfg->k.nid, sk->key);
+
+ if (ct_len < 0) {
+ log_err_id(id, "Failed to encapsulate KEM.");
+ return -ECRYPT;
+ }
+
+ kex->len = (size_t) ct_len;
+
+ log_dbg_id(id, "Server encaps: generated CT, len=%zd.", ct_len);
+
+ return 0;
+}
+
+static int do_server_kex_kem(const struct name_info * info,
+ struct oap_hdr * peer_hdr,
+ struct sec_config * kcfg,
+ buffer_t * kex,
+ struct crypt_sk * sk)
+{
+ int ret;
+
+ kcfg->x.mode = peer_hdr->kex_flags.role;
+
+ if (kcfg->x.mode == KEM_MODE_CLIENT_ENCAP) {
+ ret = do_server_kem_decap(info, peer_hdr, kcfg, sk);
+ kex->len = 0;
+ } else {
+ ret = do_server_kem_encap(peer_hdr, kcfg, kex, sk);
+ }
+
+ return ret;
+}
+
+static int do_server_kex_dhe(const struct oap_hdr * peer_hdr,
+ struct sec_config * kcfg,
+ buffer_t * kex,
+ struct crypt_sk * sk)
+{
+ ssize_t key_len;
+ void * epkp;
+ int ret;
+ uint8_t * id = peer_hdr->id.data;
+
+ key_len = kex_pkp_create(kcfg, &epkp, kex->data);
+ if (key_len < 0) {
+ log_err_id(id, "Failed to generate key pair.");
+ return -ECRYPT;
+ }
+
+ kex->len = (size_t) key_len;
+
+ log_dbg_id(id, "Generated %s ephemeral keys.", kcfg->x.str);
+
+ ret = kex_dhe_derive(kcfg, epkp, peer_hdr->kex, sk->key);
+ if (ret < 0) {
+ log_err_id(id, "Failed to derive secret.");
+ kex_pkp_destroy(epkp);
+ return -ECRYPT;
+ }
+
+ kex_pkp_destroy(epkp);
+
+ return 0;
+}
+
+int do_server_kex(const struct name_info * info,
+ struct oap_hdr * peer_hdr,
+ struct sec_config * kcfg,
+ buffer_t * kex,
+ struct crypt_sk * sk)
+{
+ char algo_buf[KEX_ALGO_BUFSZ];
+ uint8_t * id;
+
+ id = peer_hdr->id.data;
+
+ /* No KEX data from client */
+ if (peer_hdr->kex.len == 0) {
+ if (IS_KEX_ALGO_SET(kcfg)) {
+ log_warn_id(id, "KEX requested without info.");
+ return -ECRYPT;
+ }
+ return 0;
+ }
+
+ if (negotiate_kex(peer_hdr, kcfg) < 0)
+ return -ECRYPT;
+
+ if (OAP_KEX_ROLE(peer_hdr) != KEM_MODE_CLIENT_ENCAP) {
+ /* Server encapsulation or DHE: extract algo from DER PK */
+ if (get_algo_from_peer_key(peer_hdr, algo_buf) < 0)
+ return -ECRYPT;
+
+ SET_KEX_ALGO(kcfg, algo_buf);
+ }
+
+ /* Dispatch based on algorithm type */
+ if (IS_KEM_ALGORITHM(kcfg->x.str))
+ return do_server_kex_kem(info, peer_hdr, kcfg, kex, sk);
+ else
+ return do_server_kex_dhe(peer_hdr, kcfg, kex, sk);
+}
+
+int oap_srv_process(const struct name_info * info,
+ buffer_t req_buf,
+ buffer_t * rsp_buf,
+ buffer_t * data,
+ struct crypt_sk * sk)
+{
+ struct oap_hdr peer_hdr;
+ struct oap_hdr local_hdr;
+ struct sec_config kcfg;
+ uint8_t kex_buf[MSGBUFSZ];
+ uint8_t hash_buf[MAX_HASH_SIZE];
+ buffer_t req_hash = BUF_INIT;
+ ssize_t hash_ret;
+ char cli_name[NAME_SIZE + 1]; /* TODO */
+ uint8_t * id;
+ void * pkp = NULL;
+ void * crt = NULL;
+ int req_md_nid;
+
+ assert(info != NULL);
+ assert(rsp_buf != NULL);
+ assert(data != NULL);
+ assert(sk != NULL);
+
+ sk->nid = NID_undef;
+
+ memset(&peer_hdr, 0, sizeof(peer_hdr));
+ memset(&local_hdr, 0, sizeof(local_hdr));
+ clrbuf(*rsp_buf);
+
+ log_dbg("Processing OAP request for %s.", info->name);
+
+ /* Load server credentials */
+ if (load_srv_credentials(info, &pkp, &crt) < 0) {
+ log_err("Failed to load security keys for %s.", info->name);
+ goto fail_cred;
+ }
+
+ /* Load KEX config */
+ if (load_srv_kex_config(info, &kcfg) < 0) {
+ log_err("Failed to load KEX config for %s.", info->name);
+ goto fail_kex;
+ }
+
+ sk->nid = kcfg.c.nid;
+
+ /* Decode incoming header (NID_undef = request, no hash) */
+ if (oap_hdr_decode(&peer_hdr, req_buf, NID_undef) < 0) {
+ log_err("Failed to decode OAP header.");
+ goto fail_auth;
+ }
+
+ debug_oap_hdr_rcv(&peer_hdr);
+
+ id = peer_hdr.id.data; /* Logging */
+
+ /* Check for replay */
+ if (oap_check_hdr(&peer_hdr) < 0) {
+ log_err_id(id, "OAP header failed replay check.");
+ goto fail_auth;
+ }
+
+ /* Authenticate client before processing KEX data */
+ oap_hdr_init(&local_hdr, peer_hdr.id, kex_buf, *data, NID_undef);
+
+ if (oap_auth_peer(cli_name, &local_hdr, &peer_hdr) < 0) {
+ log_err_id(id, "Failed to authenticate client.");
+ goto fail_auth;
+ }
+
+ if (do_server_kex(info, &peer_hdr, &kcfg, &local_hdr.kex, sk) < 0)
+ goto fail_kex;
+
+ /* Build response header with hash of client request */
+ local_hdr.nid = sk->nid;
+
+ /* Use client's md_nid, defaulting to SHA-384 for PQC */
+ req_md_nid = peer_hdr.md_nid != NID_undef ? peer_hdr.md_nid : NID_sha384;
+
+ /* Compute request hash using client's md_nid */
+ hash_ret = md_digest(req_md_nid, req_buf, hash_buf);
+ if (hash_ret < 0) {
+ log_err_id(id, "Failed to hash request.");
+ goto fail_auth;
+ }
+ req_hash.data = hash_buf;
+ req_hash.len = (size_t) hash_ret;
+
+ if (oap_hdr_encode(&local_hdr, pkp, crt, &kcfg,
+ req_hash, req_md_nid) < 0) {
+ log_err_id(id, "Failed to create OAP response header.");
+ goto fail_auth;
+ }
+
+ debug_oap_hdr_snd(&local_hdr);
+
+ if (oap_hdr_copy_data(&peer_hdr, data) < 0) {
+ log_err_id(id, "Failed to copy client data.");
+ goto fail_data;
+ }
+
+ /* Transfer ownership of response buffer */
+ *rsp_buf = local_hdr.hdr;
+
+ log_info_id(id, "OAP request processed for %s.", info->name);
+
+ crypt_free_crt(crt);
+ crypt_free_key(pkp);
+
+ return 0;
+
+ fail_data:
+ oap_hdr_fini(&local_hdr);
+ fail_auth:
+ crypt_free_crt(crt);
+ crypt_free_key(pkp);
+ fail_cred:
+ return -EAUTH;
+
+ fail_kex:
+ crypt_free_crt(crt);
+ crypt_free_key(pkp);
+ return -ECRYPT;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2026-01-29 18:56:30 +0000