157 lines
3.7 KiB
Diff
157 lines
3.7 KiB
Diff
commit 2c3ef499bfffce3cfd315edeebf202850ba4e00a
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Author: Jakub Jelen <jjelen@redhat.com>
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Date: Tue Apr 16 15:35:18 2019 +0200
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Use the new OpenSSL KDF
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diff --git a/configure.ac b/configure.ac
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index 2a455e4e..e01c3d43 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -2712,6 +2712,7 @@ if test "x$openssl" = "xyes" ; then
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HMAC_CTX_init \
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RSA_generate_key_ex \
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RSA_get_default_method \
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+ EVP_KDF_CTX_new \
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])
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# OpenSSL_add_all_algorithms may be a macro.
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diff --git a/kex.c b/kex.c
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index b6f041f4..1fbce2bb 100644
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--- a/kex.c
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+++ b/kex.c
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@@ -38,6 +38,11 @@
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#ifdef WITH_OPENSSL
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#include <openssl/crypto.h>
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#include <openssl/dh.h>
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+# ifdef HAVE_EVP_KDF_CTX_NEW
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+# include <openssl/kdf.h>
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+# include <openssl/param_build.h>
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+# include <openssl/core_names.h>
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+# endif
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#endif
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#include "ssh.h"
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@@ -942,6 +945,112 @@ kex_choose_conf(struct ssh *ssh)
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return r;
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}
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+#ifdef HAVE_EVP_KDF_CTX_NEW
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+static const char *
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+digest_to_md(int digest_type)
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+{
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+ switch (digest_type) {
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+ case SSH_DIGEST_SHA1:
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+ return SN_sha1;
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+ case SSH_DIGEST_SHA256:
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+ return SN_sha256;
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+ case SSH_DIGEST_SHA384:
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+ return SN_sha384;
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+ case SSH_DIGEST_SHA512:
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+ return SN_sha512;
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+ }
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+ return NULL;
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+}
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+
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+static int
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+derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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+ const struct sshbuf *shared_secret, u_char **keyp)
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+{
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+ struct kex *kex = ssh->kex;
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+ u_char *key = NULL;
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+ int r, key_len;
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+
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+ EVP_KDF *kdf = EVP_KDF_fetch(NULL, "SSHKDF", NULL);
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+ EVP_KDF_CTX *ctx = NULL;
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+ OSSL_PARAM_BLD *param_bld = OSSL_PARAM_BLD_new();
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+ OSSL_PARAM *params = NULL;
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+ const char *md = digest_to_md(kex->hash_alg);
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+ char keytype = (char)id;
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+
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+ if (!kdf) {
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+ r = SSH_ERR_LIBCRYPTO_ERROR;
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+ goto out;
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+ }
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+ ctx = EVP_KDF_CTX_new(kdf);
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+ EVP_KDF_free(kdf);
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+ if (!ctx) {
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+ r = SSH_ERR_LIBCRYPTO_ERROR;
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+ goto out;
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+ }
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+ if (md == NULL) {
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+ r = SSH_ERR_INVALID_ARGUMENT;
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+ goto out;
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+ }
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+
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+ if (param_bld == NULL) {
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+ EVP_KDF_CTX_free(ctx);
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+ return -1;
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+ }
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+ if ((key_len = ssh_digest_bytes(kex->hash_alg)) == 0) {
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+ r = SSH_ERR_INVALID_ARGUMENT;
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+ goto out;
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+ }
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+
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+ key_len = ROUNDUP(need, key_len);
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+ if ((key = calloc(1, key_len)) == NULL) {
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+ r = SSH_ERR_ALLOC_FAIL;
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+ goto out;
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+ }
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+
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+ r = OSSL_PARAM_BLD_push_utf8_string(param_bld, OSSL_KDF_PARAM_DIGEST,
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+ md, strlen(md)) && /* SN */
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+ OSSL_PARAM_BLD_push_octet_string(param_bld, OSSL_KDF_PARAM_KEY,
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+ sshbuf_ptr(shared_secret), sshbuf_len(shared_secret)) &&
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+ OSSL_PARAM_BLD_push_octet_string(param_bld, OSSL_KDF_PARAM_SSHKDF_XCGHASH,
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+ hash, hashlen) &&
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+ OSSL_PARAM_BLD_push_octet_string(param_bld, OSSL_KDF_PARAM_SSHKDF_SESSION_ID,
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+ sshbuf_ptr(kex->session_id), sshbuf_len(kex->session_id)) &&
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+ OSSL_PARAM_BLD_push_utf8_string(param_bld, OSSL_KDF_PARAM_SSHKDF_TYPE,
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+ &keytype, 1);
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+ if (r != 1) {
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+ r = SSH_ERR_LIBCRYPTO_ERROR;
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+ goto out;
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+ }
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+
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+ params = OSSL_PARAM_BLD_to_param(param_bld);
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+ if (params == NULL) {
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+ r = SSH_ERR_LIBCRYPTO_ERROR;
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+ goto out;
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+ }
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+ r = EVP_KDF_derive(ctx, key, key_len, params);
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+ if (r != 1) {
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+ r = SSH_ERR_LIBCRYPTO_ERROR;
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+ goto out;
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+ }
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+#ifdef DEBUG_KEX
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+ fprintf(stderr, "key '%c'== ", id);
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+ dump_digest("key", key, key_len);
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+#endif
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+ *keyp = key;
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+ key = NULL;
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+ r = 0;
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+
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+out:
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+ OSSL_PARAM_BLD_free(param_bld);
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+ OSSL_PARAM_free(params);
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+ free (key);
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+ EVP_KDF_CTX_free(ctx);
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+ if (r < 0) {
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+ return r;
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+ }
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+ return 0;
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+}
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+#else
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static int
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derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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const struct sshbuf *shared_secret, u_char **keyp)
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@@ -1004,6 +1096,7 @@ derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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ssh_digest_free(hashctx);
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return r;
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}
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+#endif /* HAVE_OPENSSL_EVP_KDF_CTX_NEW */
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#define NKEYS 6
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int
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