make Chacha20-POLY1305 context struct opaque; ok tb@ as part of a larger

diff at a2k20

3 files changed, 35 insertions, 21 deletions

diff --git a/usr.bin/ssh/cipher-chachapoly.c b/usr.bin/ssh/cipher-chachapoly.c
index e5746dd4685..05c0c916c12 100644
--- a/usr.bin/ssh/cipher-chachapoly.c
+++ b/usr.bin/ssh/cipher-chachapoly.c
@@ -14,7 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $OpenBSD: cipher-chachapoly.c,v 1.8 2016/08/03 05:41:57 djm Exp $ */
+/* $OpenBSD: cipher-chachapoly.c,v 1.9 2020/04/03 04:27:03 djm Exp $ */
 
 #include <sys/types.h>
 #include <stdarg.h> /* needed for log.h */
@@ -26,15 +26,28 @@
 #include "ssherr.h"
 #include "cipher-chachapoly.h"
 
-int
-chachapoly_init(struct chachapoly_ctx *ctx,
-    const u_char *key, u_int keylen)
+struct chachapoly_ctx {
+	struct chacha_ctx main_ctx, header_ctx;
+};
+
+struct chachapoly_ctx *
+chachapoly_new(const u_char *key, u_int keylen)
 {
+	struct chachapoly_ctx *ctx;
+
 	if (keylen != (32 + 32)) /* 2 x 256 bit keys */
-		return SSH_ERR_INVALID_ARGUMENT;
+		return NULL;
+	if ((ctx = calloc(1, sizeof(*ctx))) == NULL)
+		return NULL;
 	chacha_keysetup(&ctx->main_ctx, key, 256);
 	chacha_keysetup(&ctx->header_ctx, key + 32, 256);
-	return 0;
+	return ctx;
+}
+
+void
+chachapoly_free(struct chachapoly_ctx *cpctx)
+{
+	freezero(cpctx, sizeof(*cpctx));
 }
 
 /*
diff --git a/usr.bin/ssh/cipher-chachapoly.h b/usr.bin/ssh/cipher-chachapoly.h
index b7072be7d9d..026d2de93a3 100644
--- a/usr.bin/ssh/cipher-chachapoly.h
+++ b/usr.bin/ssh/cipher-chachapoly.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher-chachapoly.h,v 1.4 2014/06/24 01:13:21 djm Exp $ */
+/* $OpenBSD: cipher-chachapoly.h,v 1.5 2020/04/03 04:27:03 djm Exp $ */
 
 /*
  * Copyright (c) Damien Miller 2013 <djm@mindrot.org>
@@ -24,13 +24,12 @@
 
 #define CHACHA_KEYLEN	32 /* Only 256 bit keys used here */
 
-struct chachapoly_ctx {
-	struct chacha_ctx main_ctx, header_ctx;
-};
+struct chachapoly_ctx;
+
+struct chachapoly_ctx *chachapoly_new(const u_char *key, u_int keylen)
+    __attribute__((__bounded__(__buffer__, 1, 2)));
+void chachapoly_free(struct chachapoly_ctx *cpctx);
 
-int	chachapoly_init(struct chachapoly_ctx *cpctx,
-    const u_char *key, u_int keylen)
-    __attribute__((__bounded__(__buffer__, 2, 3)));
 int	chachapoly_crypt(struct chachapoly_ctx *cpctx, u_int seqnr,
     u_char *dest, const u_char *src, u_int len, u_int aadlen, u_int authlen,
     int do_encrypt);
diff --git a/usr.bin/ssh/cipher.c b/usr.bin/ssh/cipher.c
index 441bcbd8a4c..06ac5a87618 100644
--- a/usr.bin/ssh/cipher.c
+++ b/usr.bin/ssh/cipher.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.116 2020/03/13 03:17:07 djm Exp $ */
+/* $OpenBSD: cipher.c,v 1.117 2020/04/03 04:27:03 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -55,7 +55,7 @@ struct sshcipher_ctx {
 	int	plaintext;
 	int	encrypt;
 	EVP_CIPHER_CTX *evp;
-	struct chachapoly_ctx cp_ctx; /* XXX union with evp? */
+	struct chachapoly_ctx *cp_ctx;
 	struct aesctr_ctx ac_ctx; /* XXX union with evp? */
 	const struct sshcipher *cipher;
 };
@@ -265,7 +265,8 @@ cipher_init(struct sshcipher_ctx **ccp, const struct sshcipher *cipher,
 
 	cc->cipher = cipher;
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
-		ret = chachapoly_init(&cc->cp_ctx, key, keylen);
+		cc->cp_ctx = chachapoly_new(key, keylen);
+		ret = cc->cp_ctx != NULL ? 0 : SSH_ERR_INVALID_ARGUMENT;
 		goto out;
 	}
 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
@@ -341,7 +342,7 @@ cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
    const u_char *src, u_int len, u_int aadlen, u_int authlen)
 {
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
-		return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
+		return chachapoly_crypt(cc->cp_ctx, seqnr, dest, src,
 		    len, aadlen, authlen, cc->encrypt);
 	}
 	if ((cc->cipher->flags & CFLAG_NONE) != 0) {
@@ -404,7 +405,7 @@ cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
     const u_char *cp, u_int len)
 {
 	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
-		return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
+		return chachapoly_get_length(cc->cp_ctx, plenp, seqnr,
 		    cp, len);
 	if (len < 4)
 		return SSH_ERR_MESSAGE_INCOMPLETE;
@@ -417,9 +418,10 @@ cipher_free(struct sshcipher_ctx *cc)
 {
 	if (cc == NULL)
 		return;
-	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
-		explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
-	else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
+	if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
+		chachapoly_free(cc->cp_ctx);
+		cc->cp_ctx = NULL;
+	} else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
 		explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
 #ifdef WITH_OPENSSL
 	EVP_CIPHER_CTX_free(cc->evp);