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authorpg9182 <96569817+pg9182@users.noreply.github.com>2023-03-05 18:43:07 -0500
committerpg9182 <96569817+pg9182@users.noreply.github.com>2023-04-17 14:50:10 -0400
commit35e91aa12002f089f8624b63421f370f17e3f4c7 (patch)
treeaedafb2d63ddd22d96c3f1d864aa5a1127ed32d0 /NorthstarDLL/server/servernethooks.cpp
parent29c6aeca11a52339025b46ce7854e6f81e119fd4 (diff)
downloadNorthstarLauncher-35e91aa12002f089f8624b63421f370f17e3f4c7.tar.gz
NorthstarLauncher-35e91aa12002f089f8624b63421f370f17e3f4c7.zip
Implement Atlas sigreq1 connectionless packet
Consists of a JSON object including a type key and a HMAC-SHA256 signature using the gameserver-specific token from the masterserver as the key.
Diffstat (limited to 'NorthstarDLL/server/servernethooks.cpp')
-rw-r--r--NorthstarDLL/server/servernethooks.cpp153
1 files changed, 153 insertions, 0 deletions
diff --git a/NorthstarDLL/server/servernethooks.cpp b/NorthstarDLL/server/servernethooks.cpp
index 1a760419..c367c1e1 100644
--- a/NorthstarDLL/server/servernethooks.cpp
+++ b/NorthstarDLL/server/servernethooks.cpp
@@ -1,12 +1,139 @@
#include "core/convar/convar.h"
#include "engine/r2engine.h"
#include "shared/exploit_fixes/ns_limits.h"
+#include "masterserver/masterserver.h"
#include <string>
+#include <thread>
+#include <bcrypt.h>
AUTOHOOK_INIT()
static ConVar* Cvar_net_debug_atlas_packet;
+static ConVar* Cvar_net_debug_atlas_packet_insecure;
+
+#define HMACSHA256_LEN (256 / 8)
+BCRYPT_ALG_HANDLE HMACSHA256;
+
+static bool InitHMACSHA256()
+{
+ NTSTATUS status;
+ DWORD hashLength = NULL;
+ ULONG hashLengthSz = NULL;
+
+ if ((status = BCryptOpenAlgorithmProvider(&HMACSHA256, BCRYPT_SHA256_ALGORITHM, NULL, BCRYPT_ALG_HANDLE_HMAC_FLAG)))
+ {
+ spdlog::error("failed to initialize HMAC-SHA256: BCryptOpenAlgorithmProvider: error 0x{:08X}", (ULONG)status);
+ return false;
+ }
+
+ if ((status = BCryptGetProperty(HMACSHA256, BCRYPT_HASH_LENGTH, (PUCHAR)&hashLength, sizeof(hashLength), &hashLengthSz, 0)))
+ {
+ spdlog::error("failed to initialize HMAC-SHA256: BCryptGetProperty(BCRYPT_HASH_LENGTH): error 0x{:08X}", (ULONG)status);
+ return false;
+ }
+
+ if (hashLength != HMACSHA256_LEN)
+ {
+ spdlog::error("failed to initialize HMAC-SHA256: BCryptGetProperty(BCRYPT_HASH_LENGTH): unexpected value {}", hashLength);
+ return false;
+ }
+
+ return true;
+}
+
+// note: all Atlas connectionless packets should be idempotent so multiple attempts can be made to mitigate packet loss
+// note: all long-running Atlas connectionless packet handlers should be started in a new thread (with copies of the data) to avoid blocking
+// networking
+
+static bool VerifyHMACSHA256(std::string key, std::string sig, std::string data)
+{
+ bool result = false;
+ char hash[HMACSHA256_LEN];
+
+ NTSTATUS status;
+ BCRYPT_HASH_HANDLE h = NULL;
+
+ if ((status = BCryptCreateHash(HMACSHA256, &h, NULL, 0, (PUCHAR)key.c_str(), (ULONG)key.length(), 0)))
+ {
+ spdlog::error("failed to verify HMAC-SHA256: BCryptCreateHash: error 0x{:08X}", (ULONG)status);
+ goto cleanup;
+ }
+
+ if ((status = BCryptHashData(h, (PUCHAR)data.c_str(), (ULONG)data.length(), 0)))
+ {
+ spdlog::error("failed to verify HMAC-SHA256: BCryptHashData: error 0x{:08X}", (ULONG)status);
+ goto cleanup;
+ }
+
+ if ((status = BCryptFinishHash(h, (PUCHAR)&hash, (ULONG)sizeof(hash), 0)))
+ {
+ spdlog::error("failed to verify HMAC-SHA256: BCryptFinishHash: error 0x{:08X}", (ULONG)status);
+ goto cleanup;
+ }
+
+ if (std::string(hash, sizeof(hash)) == sig)
+ {
+ result = true;
+ goto cleanup;
+ }
+
+cleanup:
+ if (h)
+ BCryptDestroyHash(h);
+ return result;
+}
+
+static void ProcessAtlasConnectionlessPacketSigreq1(R2::netpacket_t* packet, bool dbg, std::string pType, std::string pData)
+{
+ if (pData.length() < HMACSHA256_LEN)
+ {
+ if (dbg)
+ spdlog::warn("ignoring Atlas connectionless packet (size={} type={}): invalid: too short for signature", packet->size, pType);
+ return;
+ }
+
+ std::string pSig; // is binary data, not actually an ASCII string
+ pSig = pData.substr(0, HMACSHA256_LEN);
+ pData = pData.substr(HMACSHA256_LEN);
+
+ if (!g_pMasterServerManager || !g_pMasterServerManager->m_sOwnServerAuthToken[0])
+ {
+ if (dbg)
+ spdlog::warn(
+ "ignoring Atlas connectionless packet (size={} type={}): invalid (data={}): no masterserver token yet",
+ packet->size,
+ pType,
+ pData);
+ return;
+ }
+
+ if (!VerifyHMACSHA256(std::string(g_pMasterServerManager->m_sOwnServerAuthToken), pSig, pData))
+ {
+ if (!Cvar_net_debug_atlas_packet_insecure->GetBool())
+ {
+ if (dbg)
+ spdlog::warn(
+ "ignoring Atlas connectionless packet (size={} type={}): invalid: invalid signature (key={})",
+ packet->size,
+ pType,
+ std::string(g_pMasterServerManager->m_sOwnServerAuthToken));
+ return;
+ }
+ spdlog::warn(
+ "processing Atlas connectionless packet (size={} type={}) with invalid signature due to net_debug_atlas_packet_insecure",
+ packet->size,
+ pType);
+ }
+
+ if (dbg)
+ spdlog::info("got Atlas connectionless packet (size={} type={} data={})", packet->size, pType, pData);
+
+ std::thread t([pData] { g_pMasterServerManager->ProcessConnectionlessPacketSigreq1(pData); });
+ t.detach();
+
+ return;
+}
static void ProcessAtlasConnectionlessPacket(R2::netpacket_t* packet)
{
@@ -25,6 +152,13 @@ static void ProcessAtlasConnectionlessPacket(R2::netpacket_t* packet)
}
}
+ // v1 HMACSHA256-signed masterserver request
+ if (pType == "sigreq1")
+ {
+ ProcessAtlasConnectionlessPacketSigreq1(packet, dbg, pType, pData);
+ return;
+ }
+
if (dbg)
spdlog::warn("ignoring Atlas connectionless packet (size={} type={}): unknown type", packet->size, pType);
return;
@@ -46,10 +180,29 @@ ON_DLL_LOAD_RELIESON("engine.dll", ServerNetHooks, ConVar, (CModule module))
{
AUTOHOOK_DISPATCH_MODULE(engine.dll)
+ if (!InitHMACSHA256())
+ throw std::runtime_error("failed to initialize bcrypt");
+
+ if (!VerifyHMACSHA256(
+ "test",
+ "\x88\xcd\x21\x08\xb5\x34\x7d\x97\x3c\xf3\x9c\xdf\x90\x53\xd7\xdd\x42\x70\x48\x76\xd8\xc9\xa9\xbd\x8e\x2d\x16\x82\x59\xd3\xdd"
+ "\xf7",
+ "test"))
+ throw std::runtime_error("bcrypt HMAC-SHA256 is broken");
+
Cvar_net_debug_atlas_packet = new ConVar(
"net_debug_atlas_packet",
"0",
FCVAR_NONE,
"Whether to log detailed debugging information for Atlas connectionless packets (warning: this allows unlimited amounts of "
"arbitrary data to be logged)");
+
+ Cvar_net_debug_atlas_packet_insecure = new ConVar(
+ "net_debug_atlas_packet_insecure",
+ "0",
+ FCVAR_NONE,
+ "Whether to disable signature verification for Atlas connectionless packets (DANGEROUS: this allows anyone to impersonate Atlas)");
+
+ if (Cvar_net_debug_atlas_packet_insecure->GetBool())
+ spdlog::warn("DANGEROUS: Atlas connectionless packet signature verification disabled; anyone will be able to impersonate Atlas");
}