- djm@cvs.openbsd.org 2014/01/09 23:20:00

     [digest.c digest.h hostfile.c kex.c kex.h kexc25519.c kexc25519c.c]
     [kexc25519s.c kexdh.c kexecdh.c kexecdhc.c kexecdhs.c kexgex.c kexgexc.c]
     [kexgexs.c key.c key.h roaming_client.c roaming_common.c schnorr.c]
     [schnorr.h ssh-dss.c ssh-ecdsa.c ssh-rsa.c sshconnect2.c]
     Introduce digest API and use it to perform all hashing operations
     rather than calling OpenSSL EVP_Digest* directly. Will make it easier
     to build a reduced-feature OpenSSH without OpenSSL in future;
     feedback, ok markus@

1 files changed, 53 insertions, 41 deletions

diff --git a/kex.c b/kex.c
index b38bae0f..dbb1a981 100644
--- a/kex.c
+++ b/kex.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.93 2013/11/07 11:58:27 dtucker Exp $ */
+/* $OpenBSD: kex.c,v 1.94 2014/01/09 23:20:00 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -49,6 +49,7 @@
 #include "dispatch.h"
 #include "monitor.h"
 #include "roaming.h"
+#include "digest.h"
 
 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
 # if defined(HAVE_EVP_SHA256)
@@ -66,26 +67,30 @@ struct kexalg {
 	char *name;
 	int type;
 	int ec_nid;
-	const EVP_MD *(*mdfunc)(void);
+	int hash_alg;
 };
 static const struct kexalg kexalgs[] = {
-	{ KEX_DH1, KEX_DH_GRP1_SHA1, 0, EVP_sha1 },
-	{ KEX_DH14, KEX_DH_GRP14_SHA1, 0, EVP_sha1 },
-	{ KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, EVP_sha1 },
+	{ KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
+	{ KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
+	{ KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
 #ifdef HAVE_EVP_SHA256
-	{ KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, EVP_sha256 },
+	{ KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
 #endif
 #ifdef OPENSSL_HAS_ECC
-	{ KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, NID_X9_62_prime256v1, EVP_sha256 },
-	{ KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, EVP_sha384 },
+	{ KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
+	    NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
+	{ KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
+	    SSH_DIGEST_SHA384 },
 # ifdef OPENSSL_HAS_NISTP521
-	{ KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, EVP_sha512 },
+	{ KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
+	    SSH_DIGEST_SHA512 },
 # endif
 #endif
+	{ KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
 #ifdef HAVE_EVP_SHA256
-	{ KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, EVP_sha256 },
+	{ KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
 #endif
-	{ NULL, -1, -1, NULL},
+	{ NULL, -1, -1, -1},
 };
 
 char *
@@ -406,7 +411,7 @@ choose_kex(Kex *k, char *client, char *server)
 	if ((kexalg = kex_alg_by_name(k->name)) == NULL)
 		fatal("unsupported kex alg %s", k->name);
 	k->kex_type = kexalg->type;
-	k->evp_md = kexalg->mdfunc();
+	k->hash_alg = kexalg->hash_alg;
 	k->ec_nid = kexalg->ec_nid;
 }
 
@@ -532,27 +537,31 @@ derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
     BIGNUM *shared_secret)
 {
 	Buffer b;
-	EVP_MD_CTX md;
+	struct ssh_digest_ctx *hashctx;
 	char c = id;
 	u_int have;
-	int mdsz;
+	size_t mdsz;
 	u_char *digest;
 
-	if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
-		fatal("bad kex md size %d", mdsz);
+	if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
+		fatal("bad kex md size %zu", mdsz);
 	digest = xmalloc(roundup(need, mdsz));
 
 	buffer_init(&b);
 	buffer_put_bignum2(&b, shared_secret);
 
 	/* K1 = HASH(K || H || "A" || session_id) */
-	EVP_DigestInit(&md, kex->evp_md);
-	if (!(datafellows & SSH_BUG_DERIVEKEY))
-		EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
-	EVP_DigestUpdate(&md, hash, hashlen);
-	EVP_DigestUpdate(&md, &c, 1);
-	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
-	EVP_DigestFinal(&md, digest, NULL);
+	if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
+		fatal("%s: ssh_digest_start failed", __func__);
+	if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
+	    ssh_digest_update(hashctx, hash, hashlen) != 0 ||
+	    ssh_digest_update(hashctx, &c, 1) != 0 ||
+	    ssh_digest_update(hashctx, kex->session_id,
+	    kex->session_id_len) != 0)
+		fatal("%s: ssh_digest_update failed", __func__);
+	if (ssh_digest_final(hashctx, digest, mdsz) != 0)
+		fatal("%s: ssh_digest_final failed", __func__);
+	ssh_digest_free(hashctx);
 
 	/*
 	 * expand key:
@@ -560,12 +569,15 @@ derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
 	 * Key = K1 || K2 || ... || Kn
 	 */
 	for (have = mdsz; need > have; have += mdsz) {
-		EVP_DigestInit(&md, kex->evp_md);
-		if (!(datafellows & SSH_BUG_DERIVEKEY))
-			EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
-		EVP_DigestUpdate(&md, hash, hashlen);
-		EVP_DigestUpdate(&md, digest, have);
-		EVP_DigestFinal(&md, digest + have, NULL);
+		if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
+			fatal("%s: ssh_digest_start failed", __func__);
+		if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
+		    ssh_digest_update(hashctx, hash, hashlen) != 0 ||
+		    ssh_digest_update(hashctx, digest, have) != 0)
+			fatal("%s: ssh_digest_update failed", __func__);
+		if (ssh_digest_final(hashctx, digest + have, mdsz) != 0)
+			fatal("%s: ssh_digest_final failed", __func__);
+		ssh_digest_free(hashctx);
 	}
 	buffer_free(&b);
 #ifdef DEBUG_KEX
@@ -615,33 +627,33 @@ void
 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
     u_int8_t cookie[8], u_int8_t id[16])
 {
-	const EVP_MD *evp_md = EVP_md5();
-	EVP_MD_CTX md;
-	u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
+	u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
 	int len;
+	struct ssh_digest_ctx *hashctx;
 
-	EVP_DigestInit(&md, evp_md);
+	if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL)
+		fatal("%s: ssh_digest_start", __func__);
 
 	len = BN_num_bytes(host_modulus);
 	if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
 		fatal("%s: bad host modulus (len %d)", __func__, len);
 	BN_bn2bin(host_modulus, nbuf);
-	EVP_DigestUpdate(&md, nbuf, len);
+	if (ssh_digest_update(hashctx, nbuf, len) != 0)
+		fatal("%s: ssh_digest_update failed", __func__);
 
 	len = BN_num_bytes(server_modulus);
 	if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
 		fatal("%s: bad server modulus (len %d)", __func__, len);
 	BN_bn2bin(server_modulus, nbuf);
-	EVP_DigestUpdate(&md, nbuf, len);
-
-	EVP_DigestUpdate(&md, cookie, 8);
-
-	EVP_DigestFinal(&md, obuf, NULL);
-	memcpy(id, obuf, 16);
+	if (ssh_digest_update(hashctx, nbuf, len) != 0 ||
+	    ssh_digest_update(hashctx, cookie, 8) != 0)
+		fatal("%s: ssh_digest_update failed", __func__);
+	if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0)
+		fatal("%s: ssh_digest_final failed", __func__);
+	memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
 
 	memset(nbuf, 0, sizeof(nbuf));
 	memset(obuf, 0, sizeof(obuf));
-	memset(&md, 0, sizeof(md));
 }
 
 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)