X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=crypt.c;h=b977a07aac1b785735238cc6e3e8e419f4fabf4a;hp=580974d7d74a6b97d1f4b2d6a436adc98ba7408b;hb=60ef885705932a682097ad2b9f2379282d814e79;hpb=5d91cb9b0ed833517cc9288e9ca802d8a1b62757 diff --git a/crypt.c b/crypt.c index 580974d7..b977a07a 100644 --- a/crypt.c +++ b/crypt.c @@ -1,18 +1,24 @@ /* - * Copyright (C) 2005-2009 Andre Noll + * Copyright (C) 2005-2010 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ /** \file crypt.c openssl-based RSA encryption/decryption routines */ +#include +#include +#include +#include +#include +#include +#include + #include "para.h" #include "error.h" #include "string.h" #include "crypt.h" -#include -#include - +#include "fd.h" /** * Fill a buffer with random content. * @@ -59,11 +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; @@ -140,35 +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; } @@ -191,30 +199,114 @@ 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 + * Encrypt and send a buffer. * - * \param rsa: public rsa key - * \param challenge_nr the number to be encrypted - * \param outbuf the output buffer + * \param rc4c The rc4 crypt context. + * \param buf The buffer to send. + * \param len The size of \a buf in bytes. * - * \a outbuf must be at least 64 bytes long + * \return The return value of the underyling call to write_all(). * - * \return The size of the encrypted data on success, negative on errors + * \sa \ref write_all(), RC4(3). + */ +int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len) +{ + int ret; + unsigned char *tmp; + + assert(len); + tmp = para_malloc(len); + RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp); + ret = write_all(rc4c->fd, (char *)tmp, &len); + free(tmp); + return ret; +} + +/** + * Encrypt and send a \p NULL-terminated buffer. + * + * \param rc4c The rc4 crypt context. + * \param buf The buffer to send. + * + * \return The return value of the underyling call to rc4_send_bin_buffer(). + */ +int rc4_send_buffer(struct rc4_context *rc4c, const char *buf) +{ + return rc4_send_bin_buffer(rc4c, buf, strlen(buf)); +} + +/** + * Format, encrypt and send a buffer. + * + * \param rc4c The rc4 crypt context. + * \param fmt A format string. + * + * \return The return value of the underyling call to rc4_send_buffer(). + */ +__printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...) +{ + char *msg; + int ret; + + PARA_VSPRINTF(fmt, msg); + ret = rc4_send_buffer(rc4c, msg); + free(msg); + return ret; +} + +/** + * Receive a buffer and decrypt it. + * + * \param rc4c The rc4 crypt context. + * \param buf The buffer to write the decrypted data to. + * \param size The size of \a buf. * - * \sa para_encrypt_buffer() + * \return The number of bytes received on success, negative on errors, zero if + * the peer has performed an orderly shutdown. * + * \sa recv(2), RC4(3). */ -int para_encrypt_challenge(RSA* rsa, long unsigned challenge_nr, - unsigned char *outbuf) +int rc4_recv_bin_buffer(struct rc4_context *rc4c, char *buf, size_t size) { - unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr); - int ret = para_encrypt_buffer(rsa, inbuf, strlen((char *)inbuf), outbuf); - free(inbuf); + unsigned char *tmp = para_malloc(size); + ssize_t ret = recv(rc4c->fd, tmp, size, 0); + + if (ret > 0) + RC4(&rc4c->recv_key, ret, tmp, (unsigned char *)buf); + else if (ret < 0) + ret = -ERRNO_TO_PARA_ERROR(errno); + free(tmp); return ret; } +/** + * Receive a buffer, decrypt it and write terminating NULL byte. + * + * \param rc4c The rc4 crypt context. + * \param buf The buffer to write the decrypted data to. + * \param size The size of \a buf. + * + * Read at most \a size - 1 bytes from file descriptor given by \a rc4c, + * decrypt the received data and write a NULL byte at the end of the decrypted + * data. + * + * \return The return value of the underlying call to \ref + * rc4_recv_bin_buffer(). + */ +int rc4_recv_buffer(struct rc4_context *rc4c, char *buf, size_t size) +{ + int n; + + assert(size); + n = rc4_recv_bin_buffer(rc4c, buf, size - 1); + if (n >= 0) + buf[n] = '\0'; + else + *buf = '\0'; + return n; +}