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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2004-2009 Sage Weil <sage@newdream.net>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#include <errno.h>
#include <sstream>
#include "include/assert.h"
#include "include/ceph_features.h"
#include "common/config.h"
#include "CephxProtocol.h"
#include "CephxSessionHandler.h"
#define dout_subsys ceph_subsys_auth
int CephxSessionHandler::sign_message(Message *m)
{
bufferlist bl_plaintext, bl_encrypted;
ceph_msg_header header = m->get_header();
std::string error;
// If runtime signing option is off, just return success without signing.
if (!cct->_conf->cephx_sign_messages) {
return 0;
}
ceph_msg_footer& en_footer = m->get_footer();
::encode(header.crc, bl_plaintext);
::encode(en_footer.front_crc, bl_plaintext);
::encode(en_footer.middle_crc, bl_plaintext);
::encode(en_footer.data_crc, bl_plaintext);
ldout(cct, 10) << "sign_message: seq # " << header.seq << " CRCs are: header " << header.crc
<< " front " << en_footer.front_crc << " middle " << en_footer.middle_crc
<< " data " << en_footer.data_crc << dendl;
if (encode_encrypt(cct, bl_plaintext, key, bl_encrypted, error)) {
ldout(cct, 0) << "error encrypting message signature: " << error << dendl;
ldout(cct, 0) << "no signature put on message" << dendl;
return SESSION_SIGNATURE_FAILURE;
}
bufferlist::iterator ci = bl_encrypted.begin();
// Skip the magic number up front. PLR
ci.advance(4);
::decode(en_footer.sig, ci);
// There's potentially an issue with whether the encoding and decoding done here will work
// properly when a big endian and little endian machine are talking. We think it's OK,
// but it should be tested to be sure. PLR
// Receiver won't trust this flag to decide if msg should have been signed. It's primarily
// to debug problems where sender and receiver disagree on need to sign msg. PLR
en_footer.flags = (unsigned)en_footer.flags | CEPH_MSG_FOOTER_SIGNED;
messages_signed++;
ldout(cct, 20) << "Putting signature in client message(seq # " << header.seq << "): sig = " << en_footer.sig << dendl;
return 0;
}
int CephxSessionHandler::check_message_signature(Message *m)
{
bufferlist bl_plaintext, bl_ciphertext;
std::string sig_error;
ceph_msg_header& header = m->get_header();
ceph_msg_footer& footer = m->get_footer();
// If runtime signing option is off, just return success without checking signature.
if (!cct->_conf->cephx_sign_messages) {
return 0;
}
if ((features & CEPH_FEATURE_MSG_AUTH) == 0) {
// it's fine, we didn't negotiate this feature.
return 0;
}
signatures_checked++;
ldout(cct, 10) << "check_message_signature: seq # = " << m->get_seq() << " front_crc_ = " << footer.front_crc
<< " middle_crc = " << footer.middle_crc << " data_crc = " << footer.data_crc << dendl;
::encode(header.crc, bl_plaintext);
::encode(footer.front_crc, bl_plaintext);
::encode(footer.middle_crc, bl_plaintext);
::encode(footer.data_crc, bl_plaintext);
// Encrypt the buffer containing the checksums to calculate the signature. PLR
if (encode_encrypt(cct, bl_plaintext, key, bl_ciphertext, sig_error)) {
ldout(cct, 0) << "error in encryption for checking message signature: " << sig_error << dendl;
return (SESSION_SIGNATURE_FAILURE);
}
bufferlist::iterator ci = bl_ciphertext.begin();
// Skip the magic number at the front. PLR
ci.advance(4);
uint64_t sig_check;
::decode(sig_check, ci);
// There's potentially an issue with whether the encoding and decoding done here will work
// properly when a big endian and little endian machine are talking. We think it's OK,
// but it should be tested to be sure. PLR
if (sig_check != footer.sig) {
// Should have been signed, but signature check failed. PLR
if (!(footer.flags & CEPH_MSG_FOOTER_SIGNED)) {
ldout(cct, 0) << "SIGN: MSG " << header.seq << " Sender did not set CEPH_MSG_FOOTER_SIGNED." << dendl;
}
ldout(cct, 0) << "SIGN: MSG " << header.seq << " Message signature does not match contents." << dendl;
ldout(cct, 0) << "SIGN: MSG " << header.seq << "Signature on message:" << dendl;
ldout(cct, 0) << "SIGN: MSG " << header.seq << " sig: " << footer.sig << dendl;
ldout(cct, 0) << "SIGN: MSG " << header.seq << "Locally calculated signature:" << dendl;
ldout(cct, 0) << "SIGN: MSG " << header.seq << " sig_check:" << sig_check << dendl;
// For the moment, printing an error message to the log and returning failure is sufficient.
// In the long term, we should probably have code parsing the log looking for this kind
// of security failure, particularly when there are large numbers of them, since the latter
// is a potential sign of an attack. PLR
signatures_failed++;
ldout(cct, 0) << "Signature failed." << dendl;
return (SESSION_SIGNATURE_FAILURE);
}
// If we get here, the signature checked. PLR
signatures_matched++;
return 0;
}
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