=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/kexecdh.c,v retrieving revision 1.7 retrieving revision 1.8 diff -u -r1.7 -r1.8 --- src/usr.bin/ssh/kexecdh.c 2018/12/27 03:25:25 1.7 +++ src/usr.bin/ssh/kexecdh.c 2019/01/21 10:29:56 1.8 @@ -1,7 +1,7 @@ -/* $OpenBSD: kexecdh.c,v 1.7 2018/12/27 03:25:25 djm Exp $ */ +/* $OpenBSD: kexecdh.c,v 1.8 2019/01/21 10:29:56 djm Exp $ */ /* - * Copyright (c) 2001 Markus Friedl. All rights reserved. * Copyright (c) 2010 Damien Miller. All rights reserved. + * Copyright (c) 2019 Markus Friedl. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -26,70 +26,183 @@ #include -#include +#include #include +#include -#include -#include -#include #include -#include "ssh2.h" #include "sshkey.h" -#include "cipher.h" #include "kex.h" #include "sshbuf.h" #include "digest.h" #include "ssherr.h" +static int +kex_ecdh_dec_key_group(struct kex *, const u_char *, size_t, EC_KEY *key, + const EC_GROUP *, struct sshbuf **); + int -kex_ecdh_hash( - int hash_alg, - const EC_GROUP *ec_group, - const struct sshbuf *client_version, - const struct sshbuf *server_version, - const u_char *ckexinit, size_t ckexinitlen, - const u_char *skexinit, size_t skexinitlen, - const u_char *serverhostkeyblob, size_t sbloblen, - const EC_POINT *client_dh_pub, - const EC_POINT *server_dh_pub, - const BIGNUM *shared_secret, - u_char *hash, size_t *hashlen) +kex_ecdh_keypair(struct kex *kex) { - struct sshbuf *b; + EC_KEY *client_key = NULL; + const EC_GROUP *group; + const EC_POINT *public_key; + struct sshbuf *buf = NULL; int r; - if (*hashlen < ssh_digest_bytes(hash_alg)) - return SSH_ERR_INVALID_ARGUMENT; - if ((b = sshbuf_new()) == NULL) - return SSH_ERR_ALLOC_FAIL; - if ((r = sshbuf_put_stringb(b, client_version)) < 0 || - (r = sshbuf_put_stringb(b, server_version)) < 0 || - /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ - (r = sshbuf_put_u32(b, ckexinitlen+1)) != 0 || - (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 || - (r = sshbuf_put(b, ckexinit, ckexinitlen)) != 0 || - (r = sshbuf_put_u32(b, skexinitlen+1)) != 0 || - (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 || - (r = sshbuf_put(b, skexinit, skexinitlen)) != 0 || - (r = sshbuf_put_string(b, serverhostkeyblob, sbloblen)) != 0 || - (r = sshbuf_put_ec(b, client_dh_pub, ec_group)) != 0 || - (r = sshbuf_put_ec(b, server_dh_pub, ec_group)) != 0 || - (r = sshbuf_put_bignum2(b, shared_secret)) != 0) { - sshbuf_free(b); - return r; + if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; } -#ifdef DEBUG_KEX - sshbuf_dump(b, stderr); + if (EC_KEY_generate_key(client_key) != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + group = EC_KEY_get0_group(client_key); + public_key = EC_KEY_get0_public_key(client_key); + + if ((buf = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = sshbuf_put_ec(buf, public_key, group)) != 0 || + (r = sshbuf_get_u32(buf, NULL)) != 0) + goto out; +#ifdef DEBUG_KEXECDH + fputs("client private key:\n", stderr); + sshkey_dump_ec_key(client_key); #endif - if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) { - sshbuf_free(b); - return SSH_ERR_LIBCRYPTO_ERROR; + kex->ec_client_key = client_key; + kex->ec_group = group; + client_key = NULL; /* owned by the kex */ + kex->kem_client_pub = buf; + buf = NULL; + out: + EC_KEY_free(client_key); + sshbuf_free(buf); + return r; +} + +int +kex_ecdh_enc(struct kex *kex, const u_char *pkblob, size_t pklen, + struct sshbuf **server_blobp, struct sshbuf **shared_secretp) +{ + const EC_GROUP *group; + const EC_POINT *pub_key; + EC_KEY *server_key = NULL; + struct sshbuf *server_blob = NULL; + int r; + + *server_blobp = NULL; + *shared_secretp = NULL; + + if ((server_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; } - sshbuf_free(b); - *hashlen = ssh_digest_bytes(hash_alg); -#ifdef DEBUG_KEX - dump_digest("hash", hash, *hashlen); + if (EC_KEY_generate_key(server_key) != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + group = EC_KEY_get0_group(server_key); + +#ifdef DEBUG_KEXECDH + fputs("server private key:\n", stderr); + sshkey_dump_ec_key(server_key); #endif - return 0; + pub_key = EC_KEY_get0_public_key(server_key); + if ((server_blob = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = sshbuf_put_ec(server_blob, pub_key, group)) != 0 || + (r = sshbuf_get_u32(server_blob, NULL)) != 0) + goto out; + if ((r = kex_ecdh_dec_key_group(kex, pkblob, pklen, server_key, group, + shared_secretp)) != 0) + goto out; + *server_blobp = server_blob; + server_blob = NULL; + out: + EC_KEY_free(server_key); + sshbuf_free(server_blob); + return r; +} + +static int +kex_ecdh_dec_key_group(struct kex *kex, const u_char *pkblob, size_t pklen, + EC_KEY *key, const EC_GROUP *group, struct sshbuf **shared_secretp) +{ + struct sshbuf *buf = NULL; + BIGNUM *shared_secret = NULL; + EC_POINT *dh_pub = NULL; + u_char *kbuf = NULL; + size_t klen = 0; + int r; + + *shared_secretp = NULL; + + if ((buf = sshbuf_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = sshbuf_put_u32(buf, pklen)) != 0 || + (r = sshbuf_put(buf, pkblob, pklen)) != 0) { + goto out; + } + if ((dh_pub = EC_POINT_new(group)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if ((r = sshbuf_get_ec(buf, dh_pub, group)) != 0) { + goto out; + } + sshbuf_reset(buf); + +#ifdef DEBUG_KEXECDH + fputs("public key:\n", stderr); + sshkey_dump_ec_point(group, dh_pub); +#endif + if (sshkey_ec_validate_public(group, dh_pub) != 0) { + r = SSH_ERR_MESSAGE_INCOMPLETE; + goto out; + } + klen = (EC_GROUP_get_degree(group) + 7) / 8; + if ((kbuf = malloc(klen)) == NULL || + (shared_secret = BN_new()) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + if (ECDH_compute_key(kbuf, klen, dh_pub, key, NULL) != (int)klen || + BN_bin2bn(kbuf, klen, shared_secret) == NULL) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } +#ifdef DEBUG_KEXECDH + dump_digest("shared secret", kbuf, klen); +#endif + if ((r = sshbuf_put_bignum2(buf, shared_secret)) != 0) + goto out; + *shared_secretp = buf; + buf = NULL; + out: + EC_POINT_clear_free(dh_pub); + BN_clear_free(shared_secret); + freezero(kbuf, klen); + sshbuf_free(buf); + return r; +} + +int +kex_ecdh_dec(struct kex *kex, const u_char *pkblob, size_t pklen, + struct sshbuf **shared_secretp) +{ + int r; + + r = kex_ecdh_dec_key_group(kex, pkblob, pklen, kex->ec_client_key, + kex->ec_group, shared_secretp); + EC_KEY_free(kex->ec_client_key); + kex->ec_client_key = NULL; + return r; }