merge main to fuzz

--HG--
branch : fuzz

1 files changed, 40 insertions, 11 deletions

diff --git a/gensignkey.c b/gensignkey.c
index cdc16e6..4691de0 100644
--- a/gensignkey.c
+++ b/gensignkey.c
@@ -53,15 +53,15 @@ out:
 static int get_default_bits(enum signkey_type keytype)
 {
 	switch (keytype) {
-#ifdef DROPBEAR_RSA
+#if DROPBEAR_RSA
 		case DROPBEAR_SIGNKEY_RSA:
 			return RSA_DEFAULT_SIZE;
 #endif
-#ifdef DROPBEAR_DSS
+#if DROPBEAR_DSS
 		case DROPBEAR_SIGNKEY_DSS:
 			return DSS_DEFAULT_SIZE;
 #endif
-#ifdef DROPBEAR_ECDSA
+#if DROPBEAR_ECDSA
 		case DROPBEAR_SIGNKEY_ECDSA_KEYGEN:
 			return ECDSA_DEFAULT_SIZE;
 		case DROPBEAR_SIGNKEY_ECDSA_NISTP521:
@@ -76,10 +76,12 @@ static int get_default_bits(enum signkey_type keytype)
 	}
 }
 
-int signkey_generate(enum signkey_type keytype, int bits, const char* filename)
+/* if skip_exist is set it will silently return if the key file exists */
+int signkey_generate(enum signkey_type keytype, int bits, const char* filename, int skip_exist)
 {
 	sign_key * key = NULL;
 	buffer *buf = NULL;
+	char *fn_temp = NULL;
 	int ret = DROPBEAR_FAILURE;
 	if (bits == 0)
 	{
@@ -92,17 +94,17 @@ int signkey_generate(enum signkey_type keytype, int bits, const char* filename)
 	seedrandom();
 
 	switch(keytype) {
-#ifdef DROPBEAR_RSA
+#if DROPBEAR_RSA
 		case DROPBEAR_SIGNKEY_RSA:
 			key->rsakey = gen_rsa_priv_key(bits);
 			break;
 #endif
-#ifdef DROPBEAR_DSS
+#if DROPBEAR_DSS
 		case DROPBEAR_SIGNKEY_DSS:
 			key->dsskey = gen_dss_priv_key(bits);
 			break;
 #endif
-#ifdef DROPBEAR_ECDSA
+#if DROPBEAR_ECDSA
 		case DROPBEAR_SIGNKEY_ECDSA_KEYGEN:
 		case DROPBEAR_SIGNKEY_ECDSA_NISTP521:
 		case DROPBEAR_SIGNKEY_ECDSA_NISTP384:
@@ -126,10 +128,37 @@ int signkey_generate(enum signkey_type keytype, int bits, const char* filename)
 	sign_key_free(key);
 	key = NULL;
 	buf_setpos(buf, 0);
-	ret = buf_writefile(buf, filename);
 
-	buf_burn(buf);
-	buf_free(buf);
-	buf = NULL;
+	fn_temp = m_malloc(strlen(filename) + 30);
+	snprintf(fn_temp, strlen(filename)+30, "%s.tmp%d", filename, getpid());
+	ret = buf_writefile(buf, fn_temp);
+
+	if (ret == DROPBEAR_FAILURE) {
+		goto out;
+	}
+
+	if (link(fn_temp, filename) < 0) {
+		/* If generating keys on connection (skipexist) it's OK to get EEXIST 
+		- we probably just lost a race with another connection to generate the key */
+		if (!(skip_exist && errno == EEXIST)) {
+			dropbear_log(LOG_ERR, "Failed moving key file to %s: %s", filename,
+				strerror(errno));
+			/* XXX fallback to non-atomic copy for some filesystems? */
+			ret = DROPBEAR_FAILURE;
+			goto out;
+		}
+	}
+
+out:
+	if (buf) {
+		buf_burn(buf);
+		buf_free(buf);
+	}
+	
+	if (fn_temp) {
+		unlink(fn_temp);
+		m_free(fn_temp);
+	}
+
 	return ret;
 }