1 files changed, 55 insertions, 44 deletions

diff --git a/crypto/openssh/kexc25519.c b/crypto/openssh/kexc25519.c
index ee79b4327ee1..8d8cd4a2bae9 100644
--- a/crypto/openssh/kexc25519.c
+++ b/crypto/openssh/kexc25519.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexc25519.c,v 1.5 2014/01/31 16:39:19 tedu Exp $ */
+/* $OpenBSD: kexc25519.c,v 1.9 2015/03/26 07:00:04 djm Exp $ */
 /*
  * Copyright (c) 2001, 2013 Markus Friedl.  All rights reserved.
  * Copyright (c) 2010 Damien Miller.  All rights reserved.
@@ -35,13 +35,14 @@
 #include <openssl/bn.h>
 #include <openssl/evp.h>
 
-#include "buffer.h"
+#include "sshbuf.h"
 #include "ssh2.h"
-#include "key.h"
+#include "sshkey.h"
 #include "cipher.h"
 #include "kex.h"
 #include "log.h"
 #include "digest.h"
+#include "ssherr.h"
 
 extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE],
     const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE])
@@ -58,65 +59,75 @@ kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
 	crypto_scalarmult_curve25519(pub, key, basepoint);
 }
 
-void
+int
 kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
-    const u_char pub[CURVE25519_SIZE], Buffer *out)
+    const u_char pub[CURVE25519_SIZE], struct sshbuf *out)
 {
 	u_char shared_key[CURVE25519_SIZE];
+	int r;
+
+	/* Check for all-zero public key */
+	explicit_bzero(shared_key, CURVE25519_SIZE);
+	if (timingsafe_bcmp(pub, shared_key, CURVE25519_SIZE) == 0)
+		return SSH_ERR_KEY_INVALID_EC_VALUE;
 
 	crypto_scalarmult_curve25519(shared_key, key, pub);
 #ifdef DEBUG_KEXECDH
 	dump_digest("shared secret", shared_key, CURVE25519_SIZE);
 #endif
-	buffer_clear(out);
-	buffer_put_bignum2_from_string(out, shared_key, CURVE25519_SIZE);
+	sshbuf_reset(out);
+	r = sshbuf_put_bignum2_bytes(out, shared_key, CURVE25519_SIZE);
 	explicit_bzero(shared_key, CURVE25519_SIZE);
+	return r;
 }
 
-void
+int
 kex_c25519_hash(
     int hash_alg,
-    char *client_version_string,
-    char *server_version_string,
-    char *ckexinit, int ckexinitlen,
-    char *skexinit, int skexinitlen,
-    u_char *serverhostkeyblob, int sbloblen,
+    const char *client_version_string,
+    const char *server_version_string,
+    const char *ckexinit, size_t ckexinitlen,
+    const char *skexinit, size_t skexinitlen,
+    const u_char *serverhostkeyblob, size_t sbloblen,
     const u_char client_dh_pub[CURVE25519_SIZE],
     const u_char server_dh_pub[CURVE25519_SIZE],
-    const u_char *shared_secret, u_int secretlen,
-    u_char **hash, u_int *hashlen)
+    const u_char *shared_secret, size_t secretlen,
+    u_char *hash, size_t *hashlen)
 {
-	Buffer b;
-	static u_char digest[SSH_DIGEST_MAX_LENGTH];
-
-	buffer_init(&b);
-	buffer_put_cstring(&b, client_version_string);
-	buffer_put_cstring(&b, server_version_string);
-
-	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
-	buffer_put_int(&b, ckexinitlen+1);
-	buffer_put_char(&b, SSH2_MSG_KEXINIT);
-	buffer_append(&b, ckexinit, ckexinitlen);
-	buffer_put_int(&b, skexinitlen+1);
-	buffer_put_char(&b, SSH2_MSG_KEXINIT);
-	buffer_append(&b, skexinit, skexinitlen);
-
-	buffer_put_string(&b, serverhostkeyblob, sbloblen);
-	buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE);
-	buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE);
-	buffer_append(&b, shared_secret, secretlen);
-
+	struct sshbuf *b;
+	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_cstring(b, client_version_string)) < 0 ||
+	    (r = sshbuf_put_cstring(b, server_version_string)) < 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_string(b, client_dh_pub, CURVE25519_SIZE)) < 0 ||
+	    (r = sshbuf_put_string(b, server_dh_pub, CURVE25519_SIZE)) < 0 ||
+	    (r = sshbuf_put(b, shared_secret, secretlen)) < 0) {
+		sshbuf_free(b);
+		return r;
+	}
 #ifdef DEBUG_KEX
-	buffer_dump(&b);
+	sshbuf_dump(b, stderr);
 #endif
-	if (ssh_digest_buffer(hash_alg, &b, digest, sizeof(digest)) != 0)
-		fatal("%s: digest_buffer failed", __func__);
-
-	buffer_free(&b);
-
+	if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
+		sshbuf_free(b);
+		return SSH_ERR_LIBCRYPTO_ERROR;
+	}
+	sshbuf_free(b);
+	*hashlen = ssh_digest_bytes(hash_alg);
 #ifdef DEBUG_KEX
-	dump_digest("hash", digest, ssh_digest_bytes(hash_alg));
+	dump_digest("hash", hash, *hashlen);
 #endif
-	*hash = digest;
-	*hashlen = ssh_digest_bytes(hash_alg);
+	return 0;
 }