X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=crypt.c;h=cdcb6149d04254a0def3bcc903823f71ae3a89e5;hp=679ba35dd07d59ec184942524f8a1bb0be786939;hb=ab273892c54e29087d2a6b0d52de8081be1b905f;hpb=a9126f461792a84c760162ecb25100f1593d427d

diff --git a/crypt.c b/crypt.c
index 679ba35d..cdcb6149 100644
--- a/crypt.c
+++ b/crypt.c
@@ -1,11 +1,12 @@
 /*
- * 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.
  */
 
 /** \file crypt.c openssl-based RSA encryption/decryption routines */
 
+#include <regex.h>
 #include <dirent.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -64,11 +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;
@@ -145,35 +164,19 @@ 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;
-	ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
+	/*
+	 * 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;
-}
-
-/**
- * decrypt the challenge number sent by para_server
- *
- * \param key_file full path of the rsa key
- * \param challenge_nr result is stored here
- * \param inbuf the input buffer
- * \param rsa_inlen the length of \a inbuf
- *
- * \return positive on success, negative on errors
- *
- * \sa para_decrypt_buffer()
- */
-int para_decrypt_challenge(char *key_file, long unsigned *challenge_nr,
-		unsigned char *inbuf, unsigned rsa_inlen)
-{
-	unsigned char *rsa_out = OPENSSL_malloc(rsa_inlen + 1);
-	int ret = para_decrypt_buffer(key_file, rsa_out, inbuf, rsa_inlen);
-
-	if (ret >= 0) {
-		rsa_out[ret] = '\0';
-		ret = sscanf((char *)rsa_out, "%lu", challenge_nr) == 1?
-			1 : -E_CHALLENGE;
-	}
-	OPENSSL_free(rsa_out);
 	return ret;
 }
 
@@ -196,32 +199,11 @@ int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
 
 	if (flen < 0)
 		return -E_ENCRYPT;
-	ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
-	return ret < 0?  -E_ENCRYPT : ret;
+	ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
+	return ret < 0? -E_ENCRYPT : ret;
 }
 
-/**
- * encrypt the given challenge number
- *
- * \param rsa: public rsa key
- * \param challenge_nr the number to be encrypted
- * \param outbuf the output buffer
- *
- * \a outbuf must be at least 64 bytes long
- *
- * \return The size of the encrypted data on success, negative on errors
- *
- * \sa para_encrypt_buffer()
- *
- */
-int para_encrypt_challenge(RSA* rsa, long unsigned challenge_nr,
-	unsigned char *outbuf)
-{
-	unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr);
-	int ret = para_encrypt_buffer(rsa, inbuf, strlen((char *)inbuf), outbuf);
-	free(inbuf);
-	return ret;
-}
+#define RC4_ALIGN 8
 
 /**
  * Encrypt and send a buffer.
@@ -238,10 +220,16 @@ int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
 {
 	int ret;
 	unsigned char *tmp;
+	static unsigned char remainder[RC4_ALIGN];
+	size_t l1 = ROUND_DOWN(len, RC4_ALIGN), l2 = ROUND_UP(len, RC4_ALIGN);
 
 	assert(len);
-	tmp = para_malloc(len);
-	RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
+	tmp = para_malloc(l2);
+	RC4(&rc4c->send_key, l1, (const unsigned char *)buf, tmp);
+	if (len > l1) {
+		memcpy(remainder, buf + l1, len - l1);
+		RC4(&rc4c->send_key, len - l1, remainder, tmp + l1);
+	}
 	ret = write_all(rc4c->fd, (char *)tmp, &len);
 	free(tmp);
 	return ret;