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Use OpenSSL KDF

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Resolves: rhbz#1631761
This commit is contained in:
Jakub Jelen 2019-05-14 13:35:14 +02:00
parent 751cd9acc7
commit f726e51d86
2 changed files with 140 additions and 0 deletions
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137
openssh-8.0p1-openssl-kdf.patch Normal file
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@ -0,0 +1,137 @@
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_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 <openssl/crypto.h>
#include <openssl/dh.h>
+# ifdef HAVE_EVP_KDF_CTX_NEW_ID
+# include <openssl/kdf.h>
+# 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

3
openssh.spec
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@ -214,6 +214,8 @@ Patch961: openssh-8.0p1-scp-tests.patch
Patch962: openssh-8.0p1-crypto-policies.patch
# Use OpenSSL high-level API to produce and verify signatures (#1707485)
Patch963: openssh-8.0p1-openssl-evp.patch
# Use OpenSSL KDF (#1631761)
Patch964: openssh-8.0p1-openssl-kdf.patch
License: BSD
Requires: /sbin/nologin
@ -420,6 +422,7 @@ popd
%patch961 -p1 -b .scp-tests
%patch962 -p1 -b .crypto-policies
%patch963 -p1 -b .openssl-evp
%patch964 -p1 -b .openssl-kdf
%patch200 -p1 -b .audit
%patch201 -p1 -b .audit-race