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Merged
merged 4 commits into from
Jul 13, 2023
Merged

p2p: Restrict self-advertisements with privacy networks to avoid fingerprinting #27411

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62d73f5
net, refactor: pass CNode instead of CNetAddr to GetLocalAddress
mzumsande Apr 11, 2023
e4d541c
net, refactor: pass reference for peer address in GetReachabilityFrom
mzumsande Apr 11, 2023
f4754b9
net: restrict self-advertisements with privacy networks
mzumsande Apr 11, 2023
e7cf865
test: add unit test for local address advertising
mzumsande Apr 12, 2023
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20 changes: 15 additions & 5 deletions src/net.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -153,7 +153,7 @@ uint16_t GetListenPort()
}

// find 'best' local address for a particular peer
bool GetLocal(CService& addr, const CNetAddr *paddrPeer)
bool GetLocal(CService& addr, const CNode& peer)
{
if (!fListen)
return false;
Expand All @@ -164,8 +164,18 @@ bool GetLocal(CService& addr, const CNetAddr *paddrPeer)
LOCK(g_maplocalhost_mutex);
for (const auto& entry : mapLocalHost)
{
// For privacy reasons, don't advertise our privacy-network address
// to other networks and don't advertise our other-network address
// to privacy networks.
const Network our_net{entry.first.GetNetwork()};
const Network peers_net{peer.ConnectedThroughNetwork()};
if (our_net != peers_net &&
(our_net == NET_ONION || our_net == NET_I2P ||
peers_net == NET_ONION || peers_net == NET_I2P)) {
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@jonatack jonatack Jul 14, 2023 •
edited
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f4754b9 It would be nice to avoid low-level Network enum value comparisons when we have built-in higher level helpers (IsTor, IsI2P) we can use.

Edit: done in #28078

continue;
}
int nScore = entry.second.nScore;
int nReachability = entry.first.GetReachabilityFrom(paddrPeer);
int nReachability = entry.first.GetReachabilityFrom(peer.addr);
if (nReachability > nBestReachability || (nReachability == nBestReachability && nScore > nBestScore))
{
addr = CService(entry.first, entry.second.nPort);
Expand Down Expand Up @@ -203,10 +213,10 @@ static std::vector<CAddress> ConvertSeeds(const std::vector<uint8_t> &vSeedsIn)
// Otherwise, return the unroutable 0.0.0.0 but filled in with
// the normal parameters, since the IP may be changed to a useful
// one by discovery.
CService GetLocalAddress(const CNetAddr& addrPeer)
CService GetLocalAddress(const CNode& peer)
{
CService addr;
if (GetLocal(addr, &addrPeer)) {
if (GetLocal(addr, peer)) {
return addr;
}
return CService{CNetAddr(), GetListenPort()};
Expand All @@ -229,7 +239,7 @@ bool IsPeerAddrLocalGood(CNode *pnode)

std::optional<CService> GetLocalAddrForPeer(CNode& node)
{
CService addrLocal{GetLocalAddress(node.addr)};
CService addrLocal{GetLocalAddress(node)};
if (gArgs.GetBoolArg("-addrmantest", false)) {
// use IPv4 loopback during addrmantest
addrLocal = CService(LookupNumeric("127.0.0.1", GetListenPort()));
Expand Down
4 changes: 2 additions & 2 deletions src/net.h
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Original file line number Diff line number Diff line change
Expand Up @@ -164,8 +164,8 @@ bool AddLocal(const CNetAddr& addr, int nScore = LOCAL_NONE);
void RemoveLocal(const CService& addr);
bool SeenLocal(const CService& addr);
bool IsLocal(const CService& addr);
bool GetLocal(CService &addr, const CNetAddr *paddrPeer = nullptr);
CService GetLocalAddress(const CNetAddr& addrPeer);
bool GetLocal(CService& addr, const CNode& peer);
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@jonatack jonatack Jul 14, 2023 •
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While touching this, the GetLocal() getter helper is unused outside the class and could be

  • moved from the header to the implementation
  • made static and nodiscard
  • converted from a bool with an out-param to a std::optional without an out-param

Edit: done in #28078

CService GetLocalAddress(const CNode& peer);
CService MaybeFlipIPv6toCJDNS(const CService& service);


Expand Down
16 changes: 6 additions & 10 deletions src/netaddress.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -723,19 +723,16 @@ std::vector<unsigned char> CNetAddr::GetAddrBytes() const

// private extensions to enum Network, only returned by GetExtNetwork,
// and only used in GetReachabilityFrom
static const int NET_UNKNOWN = NET_MAX + 0;
static const int NET_TEREDO = NET_MAX + 1;
int static GetExtNetwork(const CNetAddr *addr)
static const int NET_TEREDO = NET_MAX;
int static GetExtNetwork(const CNetAddr& addr)
{
if (addr == nullptr)
return NET_UNKNOWN;
if (addr->IsRFC4380())
if (addr.IsRFC4380())
return NET_TEREDO;
return addr->GetNetwork();
return addr.GetNetwork();
}

/** Calculates a metric for how reachable (*this) is from a given partner */
int CNetAddr::GetReachabilityFrom(const CNetAddr *paddrPartner) const
int CNetAddr::GetReachabilityFrom(const CNetAddr& paddrPartner) const
{
enum Reachability {
REACH_UNREACHABLE,
Expand All @@ -750,7 +747,7 @@ int CNetAddr::GetReachabilityFrom(const CNetAddr *paddrPartner) const
if (!IsRoutable() || IsInternal())
return REACH_UNREACHABLE;

int ourNet = GetExtNetwork(this);
int ourNet = GetExtNetwork(*this);
int theirNet = GetExtNetwork(paddrPartner);
bool fTunnel = IsRFC3964() || IsRFC6052() || IsRFC6145();

Expand Down Expand Up @@ -790,7 +787,6 @@ int CNetAddr::GetReachabilityFrom(const CNetAddr *paddrPartner) const
case NET_IPV6: return REACH_IPV6_WEAK;
case NET_IPV4: return REACH_IPV4;
}
case NET_UNKNOWN:
case NET_UNROUTABLE:
default:
switch(ourNet) {
Expand Down
2 changes: 1 addition & 1 deletion src/netaddress.h
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Original file line number Diff line number Diff line change
Expand Up @@ -203,7 +203,7 @@ class CNetAddr
bool HasLinkedIPv4() const;

std::vector<unsigned char> GetAddrBytes() const;
int GetReachabilityFrom(const CNetAddr* paddrPartner = nullptr) const;
int GetReachabilityFrom(const CNetAddr& paddrPartner) const;

explicit CNetAddr(const struct in6_addr& pipv6Addr, const uint32_t scope = 0);
bool GetIn6Addr(struct in6_addr* pipv6Addr) const;
Expand Down
2 changes: 1 addition & 1 deletion src/test/fuzz/netaddress.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,7 @@ FUZZ_TARGET(netaddress)
(void)CServiceHash(0, 0)(service);

const CNetAddr other_net_addr = ConsumeNetAddr(fuzzed_data_provider);
(void)net_addr.GetReachabilityFrom(&other_net_addr);
(void)net_addr.GetReachabilityFrom(other_net_addr);
(void)sub_net.Match(other_net_addr);

const CService other_service{net_addr, fuzzed_data_provider.ConsumeIntegral<uint16_t>()};
Expand Down
105 changes: 105 additions & 0 deletions src/test/net_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -904,4 +904,109 @@ BOOST_AUTO_TEST_CASE(initial_advertise_from_version_message)
TestOnlyResetTimeData();
}


BOOST_AUTO_TEST_CASE(advertise_local_address)
{
auto CreatePeer = [](const CAddress& addr) {
return std::make_unique<CNode>(/*id=*/0,
/*sock=*/nullptr,
addr,
/*nKeyedNetGroupIn=*/0,
/*nLocalHostNonceIn=*/0,
CAddress{},
/*pszDest=*/std::string{},
ConnectionType::OUTBOUND_FULL_RELAY,
/*inbound_onion=*/false);
};
SetReachable(NET_CJDNS, true);

CAddress addr_ipv4{Lookup("1.2.3.4", 8333, false).value(), NODE_NONE};
BOOST_REQUIRE(addr_ipv4.IsValid());
BOOST_REQUIRE(addr_ipv4.IsIPv4());

CAddress addr_ipv6{Lookup("1122:3344:5566:7788:9900:aabb:ccdd:eeff", 8333, false).value(), NODE_NONE};
BOOST_REQUIRE(addr_ipv6.IsValid());
BOOST_REQUIRE(addr_ipv6.IsIPv6());

CAddress addr_ipv6_tunnel{Lookup("2002:3344:5566:7788:9900:aabb:ccdd:eeff", 8333, false).value(), NODE_NONE};
BOOST_REQUIRE(addr_ipv6_tunnel.IsValid());
BOOST_REQUIRE(addr_ipv6_tunnel.IsIPv6());
BOOST_REQUIRE(addr_ipv6_tunnel.IsRFC3964());

CAddress addr_teredo{Lookup("2001:0000:5566:7788:9900:aabb:ccdd:eeff", 8333, false).value(), NODE_NONE};
BOOST_REQUIRE(addr_teredo.IsValid());
BOOST_REQUIRE(addr_teredo.IsIPv6());
BOOST_REQUIRE(addr_teredo.IsRFC4380());

CAddress addr_onion;
BOOST_REQUIRE(addr_onion.SetSpecial("pg6mmjiyjmcrsslvykfwnntlaru7p5svn6y2ymmju6nubxndf4pscryd.onion"));
BOOST_REQUIRE(addr_onion.IsValid());
BOOST_REQUIRE(addr_onion.IsTor());

CAddress addr_i2p;
BOOST_REQUIRE(addr_i2p.SetSpecial("udhdrtrcetjm5sxzskjyr5ztpeszydbh4dpl3pl4utgqqw2v4jna.b32.i2p"));
BOOST_REQUIRE(addr_i2p.IsValid());
BOOST_REQUIRE(addr_i2p.IsI2P());

CService service_cjdns{Lookup("fc00:3344:5566:7788:9900:aabb:ccdd:eeff", 8333, false).value(), NODE_NONE};
CAddress addr_cjdns{MaybeFlipIPv6toCJDNS(service_cjdns), NODE_NONE};
BOOST_REQUIRE(addr_cjdns.IsValid());
BOOST_REQUIRE(addr_cjdns.IsCJDNS());

const auto peer_ipv4{CreatePeer(addr_ipv4)};
const auto peer_ipv6{CreatePeer(addr_ipv6)};
const auto peer_ipv6_tunnel{CreatePeer(addr_ipv6_tunnel)};
const auto peer_teredo{CreatePeer(addr_teredo)};
const auto peer_onion{CreatePeer(addr_onion)};
const auto peer_i2p{CreatePeer(addr_i2p)};
const auto peer_cjdns{CreatePeer(addr_cjdns)};

// one local clearnet address - advertise to all but privacy peers
AddLocal(addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_ipv4) == addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_ipv6) == addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_ipv6_tunnel) == addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_teredo) == addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_cjdns) == addr_ipv4);
BOOST_CHECK(!GetLocalAddress(*peer_onion).IsValid());
BOOST_CHECK(!GetLocalAddress(*peer_i2p).IsValid());
RemoveLocal(addr_ipv4);

// local privacy addresses - don't advertise to clearnet peers
AddLocal(addr_onion);
AddLocal(addr_i2p);
BOOST_CHECK(!GetLocalAddress(*peer_ipv4).IsValid());
BOOST_CHECK(!GetLocalAddress(*peer_ipv6).IsValid());
BOOST_CHECK(!GetLocalAddress(*peer_ipv6_tunnel).IsValid());
BOOST_CHECK(!GetLocalAddress(*peer_teredo).IsValid());
BOOST_CHECK(!GetLocalAddress(*peer_cjdns).IsValid());
BOOST_CHECK(GetLocalAddress(*peer_onion) == addr_onion);
BOOST_CHECK(GetLocalAddress(*peer_i2p) == addr_i2p);
RemoveLocal(addr_onion);
RemoveLocal(addr_i2p);

// local addresses from all networks
AddLocal(addr_ipv4);
AddLocal(addr_ipv6);
AddLocal(addr_ipv6_tunnel);
AddLocal(addr_teredo);
AddLocal(addr_onion);
AddLocal(addr_i2p);
AddLocal(addr_cjdns);
BOOST_CHECK(GetLocalAddress(*peer_ipv4) == addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_ipv6) == addr_ipv6);
BOOST_CHECK(GetLocalAddress(*peer_ipv6_tunnel) == addr_ipv6);
BOOST_CHECK(GetLocalAddress(*peer_teredo) == addr_ipv4);
BOOST_CHECK(GetLocalAddress(*peer_onion) == addr_onion);
BOOST_CHECK(GetLocalAddress(*peer_i2p) == addr_i2p);
BOOST_CHECK(GetLocalAddress(*peer_cjdns) == addr_cjdns);
RemoveLocal(addr_ipv4);
RemoveLocal(addr_ipv6);
RemoveLocal(addr_ipv6_tunnel);
RemoveLocal(addr_teredo);
RemoveLocal(addr_onion);
RemoveLocal(addr_i2p);
RemoveLocal(addr_cjdns);
}

BOOST_AUTO_TEST_SUITE_END()