ceph/src/auth/cephx/CephxSessionHandler.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2009 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #include "CephxSessionHandler.h"
  16 #include "CephxProtocol.h"
  17
  18 #include <errno.h>
  19 #include <sstream>
  20
  21 #include "common/config.h"
  22 #include "include/ceph_features.h"
  23 #include "msg/Message.h"
  24
  25 #define dout_subsys ceph_subsys_auth
  26
  27 int CephxSessionHandler::_calc_signature(Message *m, uint64_t *psig)
  28 {
  29   const ceph_msg_header& header = m->get_header();
  30   const ceph_msg_footer& footer = m->get_footer();
  31
  32   if (!HAVE_FEATURE(features, CEPHX_V2)) {
  33     // legacy pre-mimic behavior for compatibility
  34
  35     // optimized signature calculation
  36     // - avoid temporary allocated buffers from encode_encrypt[_enc_bl]
  37     // - skip the leading 4 byte wrapper from encode_encrypt
  38     struct {
  39       __u8 v;
  40       __le64 magic;
  41       __le32 len;
  42       __le32 header_crc;
  43       __le32 front_crc;
  44       __le32 middle_crc;
  45       __le32 data_crc;
  46     } __attribute__ ((packed)) sigblock = {
  47       1, mswab(AUTH_ENC_MAGIC), mswab<uint32_t>(4*4),
  48       mswab<uint32_t>(header.crc), mswab<uint32_t>(footer.front_crc),
  49       mswab<uint32_t>(footer.middle_crc), mswab<uint32_t>(footer.data_crc)
  50     };
  51
  52     bufferlist bl_plaintext;
  53     bl_plaintext.append(buffer::create_static(sizeof(sigblock),
  54                                               (char*)&sigblock));
  55
  56     bufferlist bl_ciphertext;
  57     if (key.encrypt(cct, bl_plaintext, bl_ciphertext, NULL) < 0) {
  58       lderr(cct) << __func__ << " failed to encrypt signature block" << dendl;
  59       return -1;
  60     }
  61
  62     bufferlist::iterator ci = bl_ciphertext.begin();
  63     ::decode(*psig, ci);
  64   } else {
  65     // newer mimic+ signatures
  66     struct {
  67       __le32 header_crc;
  68       __le32 front_crc;
  69       __le32 front_len;
  70       __le32 middle_crc;
  71       __le32 middle_len;
  72       __le32 data_crc;
  73       __le32 data_len;
  74       __le32 seq_lower_word;
  75     } __attribute__ ((packed)) sigblock = {
  76       mswab<uint32_t>(header.crc),
  77       mswab<uint32_t>(footer.front_crc),
  78       mswab<uint32_t>(header.front_len),
  79       mswab<uint32_t>(footer.middle_crc),
  80       mswab<uint32_t>(header.middle_len),
  81       mswab<uint32_t>(footer.data_crc),
  82       mswab<uint32_t>(header.data_len),
  83       mswab<uint32_t>(header.seq)
  84     };
  85
  86     bufferlist bl_plaintext;
  87     bl_plaintext.append(buffer::create_static(sizeof(sigblock),
  88                                               (char*)&sigblock));
  89
  90     bufferlist bl_ciphertext;
  91     if (key.encrypt(cct, bl_plaintext, bl_ciphertext, NULL) < 0) {
  92       lderr(cct) << __func__ << " failed to encrypt signature block" << dendl;
  93       return -1;
  94     }
  95
  96     struct enc {
  97       __le64 a, b, c, d;
  98     } *penc = reinterpret_cast<enc*>(bl_ciphertext.c_str());
  99     *psig = penc->a ^ penc->b ^ penc->c ^ penc->d;
 100   }
 101
 102   ldout(cct, 10) << __func__ << " seq " << m->get_seq()
 103                  << " front_crc_ = " << footer.front_crc
 104                  << " middle_crc = " << footer.middle_crc
 105                  << " data_crc = " << footer.data_crc
 106                  << " sig = " << *psig
 107                  << dendl;
 108   return 0;
 109 }
 110
 111 int CephxSessionHandler::sign_message(Message *m)
 112 {
 113   // If runtime signing option is off, just return success without signing.
 114   if (!cct->_conf->cephx_sign_messages) {
 115     return 0;
 116   }
 117
 118   uint64_t sig;
 119   int r = _calc_signature(m, &sig);
 120   if (r < 0)
 121     return r;
 122
 123   ceph_msg_footer& f = m->get_footer();
 124   f.sig = sig;
 125   f.flags = (unsigned)f.flags | CEPH_MSG_FOOTER_SIGNED;
 126   ldout(cct, 20) << "Putting signature in client message(seq # " << m->get_seq()
 127                  << "): sig = " << sig << dendl;
 128   return 0;
 129 }
 130
 131 int CephxSessionHandler::check_message_signature(Message *m)
 132 {
 133   // If runtime signing option is off, just return success without checking signature.
 134   if (!cct->_conf->cephx_sign_messages) {
 135     return 0;
 136   }
 137   if ((features & CEPH_FEATURE_MSG_AUTH) == 0) {
 138     // it's fine, we didn't negotiate this feature.
 139     return 0;
 140   }
 141
 142   uint64_t sig;
 143   int r = _calc_signature(m, &sig);
 144   if (r < 0)
 145     return r;
 146
 147   if (sig != m->get_footer().sig) {
 148     // Should have been signed, but signature check failed.  PLR
 149     if (!(m->get_footer().flags & CEPH_MSG_FOOTER_SIGNED)) {
 150       ldout(cct, 0) << "SIGN: MSG " << m->get_seq() << " Sender did not set CEPH_MSG_FOOTER_SIGNED." << dendl;
 151     }
 152     ldout(cct, 0) << "SIGN: MSG " << m->get_seq() << " Message signature does not match contents." << dendl;
 153     ldout(cct, 0) << "SIGN: MSG " << m->get_seq() << "Signature on message:" << dendl;
 154     ldout(cct, 0) << "SIGN: MSG " << m->get_seq() << "    sig: " << m->get_footer().sig << dendl;
 155     ldout(cct, 0) << "SIGN: MSG " << m->get_seq() << "Locally calculated signature:" << dendl;
 156     ldout(cct, 0) << "SIGN: MSG " << m->get_seq() << "    sig_check:" << sig << dendl;
 157
 158     // For the moment, printing an error message to the log and
 159     // returning failure is sufficient.  In the long term, we should
 160     // probably have code parsing the log looking for this kind of
 161     // security failure, particularly when there are large numbers of
 162     // them, since the latter is a potential sign of an attack.  PLR
 163
 164     ldout(cct, 0) << "Signature failed." << dendl;
 165     return (SESSION_SIGNATURE_FAILURE);
 166   }
 167
 168   return 0;
 169 }
 170