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Problem: curve_encoding_t involves unnecesary heap allocations and copying of message data

Browse Source 
Solution: use crypto_box_easy_afternm and crypto_box_open_easy_afternm
in-place
This commit is contained in:
Simon Giesecke 2020-02-03 15:26:29 +01:00
parent 2fa8185340
commit 4177bf7445
4 changed files with 169 additions and 66 deletions
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194
src/curve_mechanism_base.cpp
View File

@ -35,7 +35,6 @@
#include "session_base.hpp"
#ifdef ZMQ_HAVE_CURVE
zmq::curve_mechanism_base_t::curve_mechanism_base_t (
session_base_t *session_,
const options_t &options_,
@ -76,35 +75,99 @@ zmq::curve_encoding_t::curve_encoding_t (const char *encode_nonce_prefix_,
{
}
// Right now, we only transport the lower two bit flags of zmq::msg_t, so they
// are binary identical, and we can just use a bitmask to select them. If we
// happened to add more flags, this might change.
static const uint8_t flag_mask = zmq::msg_t::more | zmq::msg_t::command;
static const size_t flags_len = 1;
static const size_t nonce_prefix_len = 16;
static const char message_command[] = "\x07MESSAGE";
static const size_t message_command_len = sizeof (message_command) - 1;
static const size_t message_header_len =
message_command_len + sizeof (zmq::curve_encoding_t::nonce_t);
#ifndef ZMQ_USE_LIBSODIUM
static const size_t crypto_box_MACBYTES = 16;
#endif
int zmq::curve_encoding_t::check_validity (msg_t *msg_, int *error_event_code_)
{
const size_t size = msg_->size ();
const uint8_t *const message = static_cast<uint8_t *> (msg_->data ());
if (size < message_command_len
|| 0 != memcmp (message, message_command, message_command_len)) {
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_UNEXPECTED_COMMAND;
errno = EPROTO;
return -1;
}
if (size < message_header_len + crypto_box_MACBYTES + flags_len) {
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_MESSAGE;
errno = EPROTO;
return -1;
}
{
const uint64_t nonce = get_uint64 (message + message_command_len);
if (nonce <= _cn_peer_nonce) {
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_INVALID_SEQUENCE;
errno = EPROTO;
return -1;
}
set_peer_nonce (nonce);
}
return 0;
}
int zmq::curve_encoding_t::encode (msg_t *msg_)
{
const size_t mlen = crypto_box_ZEROBYTES + 1 + msg_->size ();
uint8_t message_nonce[crypto_box_NONCEBYTES];
memcpy (message_nonce, _encode_nonce_prefix, 16);
put_uint64 (message_nonce + 16, _cn_nonce);
uint8_t flags = 0;
if (msg_->flags () & msg_t::more)
flags |= 0x01;
if (msg_->flags () & msg_t::command)
flags |= 0x02;
memcpy (message_nonce, _encode_nonce_prefix, nonce_prefix_len);
put_uint64 (message_nonce + nonce_prefix_len, get_and_inc_nonce ());
#ifdef ZMQ_USE_LIBSODIUM
const size_t mlen = flags_len + msg_->size ();
std::vector<uint8_t> message_plaintext (mlen);
#else
const size_t mlen = crypto_box_ZEROBYTES + flags_len + msg_->size ();
std::vector<uint8_t> message_plaintext_with_zerobytes (mlen);
uint8_t *const message_plaintext =
&message_plaintext_with_zerobytes[crypto_box_ZEROBYTES];
std::fill (message_plaintext.begin (),
message_plaintext.begin () + crypto_box_ZEROBYTES, 0);
message_plaintext[crypto_box_ZEROBYTES] = flags;
std::fill (message_plaintext_with_zerobytes.begin (),
message_plaintext_with_zerobytes.begin () + crypto_box_ZEROBYTES,
0);
#endif
const uint8_t flags = msg_->flags () & flag_mask;
message_plaintext[0] = flags;
// this is copying the data from insecure memory, so there is no point in
// using secure_allocator_t for message_plaintext
if (msg_->size () > 0)
memcpy (&message_plaintext[crypto_box_ZEROBYTES + 1], msg_->data (),
msg_->size ());
memcpy (&message_plaintext[flags_len], msg_->data (), msg_->size ());
#ifdef ZMQ_USE_LIBSODIUM
msg_t msg_box;
int rc =
msg_box.init_size (message_header_len + mlen + crypto_box_MACBYTES);
zmq_assert (rc == 0);
rc = crypto_box_easy_afternm (
static_cast<uint8_t *> (msg_box.data ()) + message_header_len,
&message_plaintext[0], mlen, message_nonce, _cn_precom);
zmq_assert (rc == 0);
msg_->move (msg_box);
uint8_t *const message = static_cast<uint8_t *> (msg_->data ());
#else
std::vector<uint8_t> message_box (mlen);
int rc = crypto_box_afternm (&message_box[0], &message_plaintext[0], mlen,
message_nonce, _cn_precom);
int rc =
crypto_box_afternm (&message_box[0], &message_plaintext_with_zerobytes[0],
mlen, message_nonce, _cn_precom);
zmq_assert (rc == 0);
rc = msg_->close ();
@ -113,76 +176,89 @@ int zmq::curve_encoding_t::encode (msg_t *msg_)
rc = msg_->init_size (16 + mlen - crypto_box_BOXZEROBYTES);
zmq_assert (rc == 0);
uint8_t *message = static_cast<uint8_t *> (msg_->data ());
uint8_t *const message = static_cast<uint8_t *> (msg_->data ());
memcpy (message, "\x07MESSAGE", 8);
memcpy (message + 8, message_nonce + 16, 8);
memcpy (message + 16, &message_box[crypto_box_BOXZEROBYTES],
memcpy (message + message_header_len, &message_box[crypto_box_BOXZEROBYTES],
mlen - crypto_box_BOXZEROBYTES);
#endif
_cn_nonce++;
memcpy (message, message_command, message_command_len);
memcpy (message + message_command_len, message_nonce + nonce_prefix_len,
sizeof (nonce_t));
return 0;
}
int zmq::curve_encoding_t::decode (msg_t *msg_, int *error_event_code_)
{
const size_t size = msg_->size ();
const uint8_t *message = static_cast<uint8_t *> (msg_->data ());
if (size < 8 || 0 != memcmp (message, "\x07MESSAGE", 8)) {
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_UNEXPECTED_COMMAND;
errno = EPROTO;
return -1;
int rc = check_validity (msg_, error_event_code_);
if (0 != rc) {
return rc;
}
if (size < 33) {
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_MESSAGE;
errno = EPROTO;
return -1;
}
uint8_t *const message = static_cast<uint8_t *> (msg_->data ());
uint8_t message_nonce[crypto_box_NONCEBYTES];
memcpy (message_nonce, _decode_nonce_prefix, 16);
memcpy (message_nonce + 16, message + 8, 8);
const uint64_t nonce = get_uint64 (message + 8);
if (nonce <= _cn_peer_nonce) {
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_INVALID_SEQUENCE;
errno = EPROTO;
return -1;
}
_cn_peer_nonce = nonce;
memcpy (message_nonce, _decode_nonce_prefix, nonce_prefix_len);
memcpy (message_nonce + nonce_prefix_len, message + message_command_len,
sizeof (nonce_t));
const size_t clen = crypto_box_BOXZEROBYTES + msg_->size () - 16;
#ifdef ZMQ_USE_LIBSODIUM
const size_t clen = msg_->size () - message_header_len;
std::vector<uint8_t> message_plaintext (clen);
uint8_t *const message_plaintext = message + message_header_len;
rc = crypto_box_open_easy_afternm (message_plaintext,
message + message_header_len, clen,
message_nonce, _cn_precom);
#else
const size_t clen =
crypto_box_BOXZEROBYTES + msg_->size () - message_header_len;
std::vector<uint8_t> message_plaintext_with_zerobytes (clen);
std::vector<uint8_t> message_box (clen);
std::fill (message_box.begin (),
message_box.begin () + crypto_box_BOXZEROBYTES, 0);
memcpy (&message_box[crypto_box_BOXZEROBYTES], message + 16,
msg_->size () - 16);
memcpy (&message_box[crypto_box_BOXZEROBYTES], message + message_header_len,
msg_->size () - message_header_len);
rc = crypto_box_open_afternm (&message_plaintext_with_zerobytes[0],
&message_box[0], clen, message_nonce,
_cn_precom);
const uint8_t *const message_plaintext =
&message_plaintext_with_zerobytes[crypto_box_ZEROBYTES];
#endif
int rc = crypto_box_open_afternm (&message_plaintext[0], &message_box[0],
clen, message_nonce, _cn_precom);
if (rc == 0) {
const uint8_t flags = message_plaintext[0];
#ifdef ZMQ_USE_LIBSODIUM
const size_t plaintext_size = clen - flags_len - crypto_box_MACBYTES;
if (plaintext_size > 0) {
memmove (msg_->data (), &message_plaintext[flags_len],
plaintext_size);
}
msg_->shrink (plaintext_size);
#else
rc = msg_->close ();
zmq_assert (rc == 0);
rc = msg_->init_size (clen - 1 - crypto_box_ZEROBYTES);
rc = msg_->init_size (clen - flags_len - crypto_box_ZEROBYTES);
zmq_assert (rc == 0);
const uint8_t flags = message_plaintext[crypto_box_ZEROBYTES];
if (flags & 0x01)
msg_->set_flags (msg_t::more);
if (flags & 0x02)
msg_->set_flags (msg_t::command);
// this is copying the data to insecure memory, so there is no point in
// using secure_allocator_t for message_plaintext
if (msg_->size () > 0)
memcpy (msg_->data (), &message_plaintext[crypto_box_ZEROBYTES + 1],
if (msg_->size () > 0) {
memcpy (msg_->data (), &message_plaintext[flags_len],
msg_->size ());
}
#endif
msg_->set_flags (flags & flag_mask);
} else {
// CURVE I : connection key used for MESSAGE is wrong
*error_event_code_ = ZMQ_PROTOCOL_ERROR_ZMTP_CRYPTOGRAPHIC;

15
src/curve_mechanism_base.hpp
View File

@ -64,18 +64,19 @@ class curve_encoding_t
uint8_t *get_writable_precom_buffer () { return _cn_precom; }
const uint8_t *get_precom_buffer () const { return _cn_precom; }
uint64_t get_and_inc_nonce () { return _cn_nonce++; }
void set_peer_nonce (uint64_t peer_nonce_)
{
_cn_peer_nonce = peer_nonce_;
};
typedef uint64_t nonce_t;
nonce_t get_and_inc_nonce () { return _cn_nonce++; }
void set_peer_nonce (nonce_t peer_nonce_) { _cn_peer_nonce = peer_nonce_; };
private:
int check_validity (msg_t *msg_, int *error_event_code_);
const char *_encode_nonce_prefix;
const char *_decode_nonce_prefix;
uint64_t _cn_nonce;
uint64_t _cn_peer_nonce;
nonce_t _cn_nonce;
nonce_t _cn_peer_nonce;
// Intermediary buffer used to speed up boxing and unboxing.
uint8_t _cn_precom[crypto_box_BEFORENMBYTES];

24
src/msg.cpp
View File

@ -361,6 +361,30 @@ size_t zmq::msg_t::size () const
}
}
void zmq::msg_t::shrink (size_t new_size_)
{
// Check the validity of the message.
zmq_assert (check ());
zmq_assert (new_size_ <= size ());
switch (_u.base.type) {
case type_vsm:
_u.vsm.size = static_cast<unsigned char> (new_size_);
break;
case type_lmsg:
_u.lmsg.content->size = new_size_;
break;
case type_zclmsg:
_u.zclmsg.content->size = new_size_;
break;
case type_cmsg:
_u.cmsg.size = new_size_;
break;
default:
zmq_assert (false);
}
}
unsigned char zmq::msg_t::flags () const
{
return _u.base.flags;

2
src/msg.hpp
View File

@ -161,6 +161,8 @@ class msg_t
// references drops to 0, the message is closed and false is returned.
bool rm_refs (int refs_);
void shrink (size_t new_size_);
// Size in bytes of the largest message that is still copied around
// rather than being reference-counted.
enum