commit 2c3ef499bfffce3cfd315edeebf202850ba4e00a

Author: Jakub Jelen <jjelen@redhat.com>

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 \

 	])

 	# 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 +38,11 @@

 #ifdef WITH_OPENSSL

 #include <openssl/crypto.h>

 #include <openssl/dh.h>

+# ifdef HAVE_EVP_KDF_CTX_NEW

+# include <openssl/kdf.h>

+# include <openssl/param_build.h>

+# include <openssl/core_names.h>

+# endif

 #endif

 #include "ssh.h"

@@ -942,6 +945,107 @@ kex_choose_conf(struct ssh *ssh)

 	return r;

 }

+#ifdef HAVE_EVP_KDF_CTX_NEW

+static const char *

+digest_to_md(int digest_type)

+{

+	switch (digest_type) {

+	case SSH_DIGEST_SHA1:

+		return SN_sha1;

+	case SSH_DIGEST_SHA256:

+		return SN_sha256;

+	case SSH_DIGEST_SHA384:

+		return SN_sha384;

+	case SSH_DIGEST_SHA512:

+		return SN_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;

+	u_char *key = NULL;

+	int r, key_len;

+

+	EVP_KDF *kdf = EVP_KDF_fetch(NULL, "SSHKDF", NULL);

+	EVP_KDF_CTX *ctx = EVP_KDF_CTX_new(kdf);

+	OSSL_PARAM_BLD *param_bld = OSSL_PARAM_BLD_new();

+	OSSL_PARAM *params = NULL;

+       const char *md = digest_to_md(kex->hash_alg);

+       char keytype = (char)id;

+

+	EVP_KDF_free(kdf);

+	if (!ctx) {

+		r = SSH_ERR_LIBCRYPTO_ERROR;

+		goto out;

+	}

+	if (md == NULL) {

+		r = SSH_ERR_INVALID_ARGUMENT;

+		goto out;

+	}

+

+	if (param_bld == NULL) {

+		EVP_KDF_CTX_free(ctx);

+		return -1;

+	}

+	if ((key_len = ssh_digest_bytes(kex->hash_alg)) == 0) {

+		r = SSH_ERR_INVALID_ARGUMENT;

+		goto out;

+	}

+

+	key_len = ROUNDUP(need, key_len);

+	if ((key = calloc(1, key_len)) == NULL) {

+		r = SSH_ERR_ALLOC_FAIL;

+		goto out;

+	}

+

+	r =     OSSL_PARAM_BLD_push_utf8_string(param_bld, OSSL_KDF_PARAM_DIGEST,

+		                md, strlen(md)) && /* SN */

+		OSSL_PARAM_BLD_push_octet_string(param_bld, OSSL_KDF_PARAM_KEY,

+				sshbuf_ptr(shared_secret), sshbuf_len(shared_secret)) &&

+		OSSL_PARAM_BLD_push_octet_string(param_bld, OSSL_KDF_PARAM_SSHKDF_XCGHASH,

+				hash, hashlen) &&

+		OSSL_PARAM_BLD_push_octet_string(param_bld, OSSL_KDF_PARAM_SSHKDF_SESSION_ID,

+				sshbuf_ptr(kex->session_id), sshbuf_len(kex->session_id)) &&

+		OSSL_PARAM_BLD_push_utf8_string(param_bld, OSSL_KDF_PARAM_SSHKDF_TYPE,

+				&keytype, 1);

+	if (r != 1) {

+		r = SSH_ERR_LIBCRYPTO_ERROR;

+		goto out;

+	}

+

+	params = OSSL_PARAM_BLD_to_param(param_bld);

+	if (params == NULL) {

+		r = SSH_ERR_LIBCRYPTO_ERROR;

+		goto out;

+	}

+	r = EVP_KDF_derive(ctx, key, key_len, params);

+	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:

+	OSSL_PARAM_BLD_free(param_bld);

+	OSSL_PARAM_free(params);

+	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 */

 #define NKEYS	6

 int