commit 2c3ef499bfffce3cfd315edeebf202850ba4e00a Author: Jakub Jelen Date: Tue Apr 16 15:35:18 2019 +0200 Use the new OpenSSL KDF diff --git a/configure.ac b/configure.ac index 2a455e4e..e01c3d43 100644 --- a/configure.ac +++ b/configure.ac @@ -2712,6 +2712,7 @@ if test "x$openssl" = "xyes" ; then HMAC_CTX_init \ RSA_generate_key_ex \ RSA_get_default_method \ + EVP_KDF_CTX_new_id \ ]) # OpenSSL_add_all_algorithms may be a macro. diff --git a/kex.c b/kex.c index b6f041f4..1fbce2bb 100644 --- a/kex.c +++ b/kex.c @@ -38,6 +38,9 @@ #ifdef WITH_OPENSSL #include #include +# ifdef HAVE_EVP_KDF_CTX_NEW_ID +# include +# endif #endif #include "ssh.h" @@ -942,6 +945,95 @@ kex_choose_conf(struct ssh *ssh) return r; } +#ifdef HAVE_EVP_KDF_CTX_NEW_ID +static const EVP_MD * +digest_to_md(int digest_type) +{ + switch (digest_type) { + case SSH_DIGEST_SHA1: + return EVP_sha1(); + case SSH_DIGEST_SHA256: + return EVP_sha256(); + case SSH_DIGEST_SHA384: + return EVP_sha384(); + case SSH_DIGEST_SHA512: + return EVP_sha512(); + } + return NULL; +} + +static int +derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen, + const struct sshbuf *shared_secret, u_char **keyp) +{ + struct kex *kex = ssh->kex; + EVP_KDF_CTX *ctx = NULL; + u_char *key = NULL; + int r, key_len; + + if ((key_len = ssh_digest_bytes(kex->hash_alg)) == 0) + return SSH_ERR_INVALID_ARGUMENT; + key_len = ROUNDUP(need, key_len); + if ((key = calloc(1, key_len)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + + ctx = EVP_KDF_CTX_new_id(EVP_KDF_SSHKDF); + if (!ctx) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + + r = EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_MD, digest_to_md(kex->hash_alg)); + if (r != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + r = EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_KEY, + sshbuf_ptr(shared_secret), sshbuf_len(shared_secret)); + if (r != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + r = EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_SSHKDF_XCGHASH, hash, hashlen); + if (r != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + r = EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_SSHKDF_TYPE, id); + if (r != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + r = EVP_KDF_ctrl(ctx, EVP_KDF_CTRL_SET_SSHKDF_SESSION_ID, + kex->session_id, kex->session_id_len); + if (r != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } + r = EVP_KDF_derive(ctx, key, key_len); + if (r != 1) { + r = SSH_ERR_LIBCRYPTO_ERROR; + goto out; + } +#ifdef DEBUG_KEX + fprintf(stderr, "key '%c'== ", id); + dump_digest("key", key, key_len); +#endif + *keyp = key; + key = NULL; + r = 0; + +out: + free (key); + EVP_KDF_CTX_free(ctx); + if (r < 0) { + return r; + } + return 0; +} +#else static int derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen, const struct sshbuf *shared_secret, u_char **keyp) @@ -1004,6 +1096,7 @@ derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen, ssh_digest_free(hashctx); return r; } +#endif /* HAVE_OPENSSL_EVP_KDF_CTX_NEW_ID */ #define NKEYS 6 int