Merge upstream-master into master

Commit ecb2c02d994b3e21994f31a70ff911667c262f1f upstream

This nearly (but not quite) corresponds to V_8_3_P1; subsequent
cherry-picks will correct this.

Bug: 162492243
Change-Id: I3c079d86435b7c25aefff4538dc89a3002b1e25b

1 files changed, 60 insertions, 75 deletions

diff --git a/ssh-dss.c b/ssh-dss.c
index 8ed19d84..fddc29cc 100644
--- a/ssh-dss.c
+++ b/ssh-dss.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-dss.c,v 1.32 2014/06/24 01:13:21 djm Exp $ */
+/* $OpenBSD: ssh-dss.c,v 1.39 2020/02/26 13:40:09 jsg Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -43,6 +43,8 @@
 #define SSHKEY_INTERNAL
 #include "sshkey.h"
 
+#include "openbsd-compat/openssl-compat.h"
+
 #define INTBLOB_LEN	20
 #define SIGBLOB_LEN	(2*INTBLOB_LEN)
 
@@ -51,6 +53,7 @@ ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
     const u_char *data, size_t datalen, u_int compat)
 {
 	DSA_SIG *sig = NULL;
+	const BIGNUM *sig_r, *sig_s;
 	u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
 	size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
 	struct sshbuf *b = NULL;
@@ -76,54 +79,40 @@ ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
 		goto out;
 	}
 
-	rlen = BN_num_bytes(sig->r);
-	slen = BN_num_bytes(sig->s);
+	DSA_SIG_get0(sig, &sig_r, &sig_s);
+	rlen = BN_num_bytes(sig_r);
+	slen = BN_num_bytes(sig_s);
 	if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
 		ret = SSH_ERR_INTERNAL_ERROR;
 		goto out;
 	}
 	explicit_bzero(sigblob, SIGBLOB_LEN);
-	BN_bn2bin(sig->r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
-	BN_bn2bin(sig->s, sigblob + SIGBLOB_LEN - slen);
-
-	if (compat & SSH_BUG_SIGBLOB) {
-		if (sigp != NULL) {
-			if ((*sigp = malloc(SIGBLOB_LEN)) == NULL) {
-				ret = SSH_ERR_ALLOC_FAIL;
-				goto out;
-			}
-			memcpy(*sigp, sigblob, SIGBLOB_LEN);
-		}
-		if (lenp != NULL)
-			*lenp = SIGBLOB_LEN;
-		ret = 0;
-	} else {
-		/* ietf-drafts */
-		if ((b = sshbuf_new()) == NULL) {
+	BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
+	BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
+
+	if ((b = sshbuf_new()) == NULL) {
+		ret = SSH_ERR_ALLOC_FAIL;
+		goto out;
+	}
+	if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
+	    (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
+		goto out;
+
+	len = sshbuf_len(b);
+	if (sigp != NULL) {
+		if ((*sigp = malloc(len)) == NULL) {
 			ret = SSH_ERR_ALLOC_FAIL;
 			goto out;
 		}
-		if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
-		    (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
-			goto out;
-		len = sshbuf_len(b);
-		if (sigp != NULL) {
-			if ((*sigp = malloc(len)) == NULL) {
-				ret = SSH_ERR_ALLOC_FAIL;
-				goto out;
-			}
-			memcpy(*sigp, sshbuf_ptr(b), len);
-		}
-		if (lenp != NULL)
-			*lenp = len;
-		ret = 0;
+		memcpy(*sigp, sshbuf_ptr(b), len);
 	}
+	if (lenp != NULL)
+		*lenp = len;
+	ret = 0;
  out:
 	explicit_bzero(digest, sizeof(digest));
-	if (sig != NULL)
-		DSA_SIG_free(sig);
-	if (b != NULL)
-		sshbuf_free(b);
+	DSA_SIG_free(sig);
+	sshbuf_free(b);
 	return ret;
 }
 
@@ -133,6 +122,7 @@ ssh_dss_verify(const struct sshkey *key,
     const u_char *data, size_t datalen, u_int compat)
 {
 	DSA_SIG *sig = NULL;
+	BIGNUM *sig_r = NULL, *sig_s = NULL;
 	u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
 	size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
 	int ret = SSH_ERR_INTERNAL_ERROR;
@@ -140,34 +130,27 @@ ssh_dss_verify(const struct sshkey *key,
 	char *ktype = NULL;
 
 	if (key == NULL || key->dsa == NULL ||
-	    sshkey_type_plain(key->type) != KEY_DSA)
+	    sshkey_type_plain(key->type) != KEY_DSA ||
+	    signature == NULL || signaturelen == 0)
 		return SSH_ERR_INVALID_ARGUMENT;
 	if (dlen == 0)
 		return SSH_ERR_INTERNAL_ERROR;
 
 	/* fetch signature */
-	if (compat & SSH_BUG_SIGBLOB) {
-		if ((sigblob = malloc(signaturelen)) == NULL)
-			return SSH_ERR_ALLOC_FAIL;
-		memcpy(sigblob, signature, signaturelen);
-		len = signaturelen;
-	} else {
-		/* ietf-drafts */
-		if ((b = sshbuf_from(signature, signaturelen)) == NULL)
-			return SSH_ERR_ALLOC_FAIL;
-		if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
-		    sshbuf_get_string(b, &sigblob, &len) != 0) {
-			ret = SSH_ERR_INVALID_FORMAT;
-			goto out;
-		}
-		if (strcmp("ssh-dss", ktype) != 0) {
-			ret = SSH_ERR_KEY_TYPE_MISMATCH;
-			goto out;
-		}
-		if (sshbuf_len(b) != 0) {
-			ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
-			goto out;
-		}
+	if ((b = sshbuf_from(signature, signaturelen)) == NULL)
+		return SSH_ERR_ALLOC_FAIL;
+	if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
+	    sshbuf_get_string(b, &sigblob, &len) != 0) {
+		ret = SSH_ERR_INVALID_FORMAT;
+		goto out;
+	}
+	if (strcmp("ssh-dss", ktype) != 0) {
+		ret = SSH_ERR_KEY_TYPE_MISMATCH;
+		goto out;
+	}
+	if (sshbuf_len(b) != 0) {
+		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+		goto out;
 	}
 
 	if (len != SIGBLOB_LEN) {
@@ -177,16 +160,21 @@ ssh_dss_verify(const struct sshkey *key,
 
 	/* parse signature */
 	if ((sig = DSA_SIG_new()) == NULL ||
-	    (sig->r = BN_new()) == NULL ||
-	    (sig->s = BN_new()) == NULL) {
+	    (sig_r = BN_new()) == NULL ||
+	    (sig_s = BN_new()) == NULL) {
 		ret = SSH_ERR_ALLOC_FAIL;
 		goto out;
 	}
-	if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
-	    (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL)) {
+	if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
+	    (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
 		ret = SSH_ERR_LIBCRYPTO_ERROR;
 		goto out;
 	}
+	if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
+		ret = SSH_ERR_LIBCRYPTO_ERROR;
+		goto out;
+	}
+	sig_r = sig_s = NULL; /* transferred */
 
 	/* sha1 the data */
 	if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
@@ -207,16 +195,13 @@ ssh_dss_verify(const struct sshkey *key,
 
  out:
 	explicit_bzero(digest, sizeof(digest));
-	if (sig != NULL)
-		DSA_SIG_free(sig);
-	if (b != NULL)
-		sshbuf_free(b);
-	if (ktype != NULL)
-		free(ktype);
-	if (sigblob != NULL) {
-		explicit_bzero(sigblob, len);
-		free(sigblob);
-	}
+	DSA_SIG_free(sig);
+	BN_clear_free(sig_r);
+	BN_clear_free(sig_s);
+	sshbuf_free(b);
+	free(ktype);
+	if (sigblob != NULL)
+		freezero(sigblob, len);
 	return ret;
 }
 #endif /* WITH_OPENSSL */