X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=crypt.c;h=917948c6185710fb828b441025b8d46a0fdc2924;hp=352c5b8d8e97832ed3d782ce3ad1984890ad5cf7;hb=fa578bf1d070161cafcbcc69ca7b810414ee1a4b;hpb=fb62100d23baea388cec78e572b0f36d051a61c0

diff --git a/crypt.c b/crypt.c
index 352c5b8d..917948c6 100644
--- a/crypt.c
+++ b/crypt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -65,11 +65,29 @@ void init_random_seed_or_die(void)
 	srandom(seed);
 }
 
+static int check_key_file(const char *file, int private)
+{
+	struct stat st;
+
+	if (stat(file, &st) != 0)
+		return -ERRNO_TO_PARA_ERROR(errno);
+	if (private != LOAD_PRIVATE_KEY)
+		return 0;
+	if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0)
+		return -E_KEY_PERM;
+	return 1;
+}
+
 static EVP_PKEY *load_key(const char *file, int private)
 {
 	BIO *key;
 	EVP_PKEY *pkey = NULL;
+	int ret = check_key_file(file, private);
 
+	if (ret < 0) {
+		PARA_ERROR_LOG("%s\n", para_strerror(-ret));
+		return NULL;
+	}
 	key = BIO_new(BIO_s_file());
 	if (!key)
 		return NULL;
@@ -146,9 +164,20 @@ int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *in
 	ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
 	if (ret < 0)
 		return ret;
+	/*
+	 * RSA is vulnerable to timing attacks. Generate a random blinding
+	 * factor to protect against this kind of attack.
+	 */
+	ret = -E_BLINDING;
+	if (RSA_blinding_on(rsa, NULL) == 0)
+		goto out;
 	ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
+	RSA_blinding_off(rsa);
+	if (ret <= 0)
+		ret = -E_DECRYPT;
+out:
 	rsa_free(rsa);
-	return (ret > 0)? ret : -E_DECRYPT;
+	return ret;
 }
 
 /**
@@ -191,7 +220,7 @@ int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
 	unsigned char *tmp;
 
 	assert(len);
-	tmp = para_malloc(len);
+	tmp = para_malloc(len + 8);
 	RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
 	ret = write_all(rc4c->fd, (char *)tmp, &len);
 	free(tmp);