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Implemented reduction of impact caused by zip-bomb exploit (#994)

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* Implemented reduction of impact caused by zip-bomb exploit
Added network security CVars:
- sv_net_incoming_decompression (0-1) Enables or disables incoming data decompression
- sv_net_incoming_decompression_max_ratio (0.0 - 100.0) Sets max allowed ratio between compressed and decompressed data. (A ratio close to 90 indicates large uncompressed data with low entropy)
- sv_net_incoming_decompression_max_size (16-65536) Adjusts max size of output data after decompression.
Added CVar sv_net_incoming_decompression_punish for ban
* Fix missing reg CVar sv_net_incoming_decompression_punish
This commit is contained in:
Dmitry Novikov 2024-04-14 01:04:03 +07:00 committed by GitHub
parent 61ee4f9269
commit 0d1bdbab67
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GPG Key ID: B5690EEEBB952194
2 changed files with 91 additions and 12 deletions
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4
README.md
View File

@ -63,6 +63,10 @@ This means that plugins that do binary code analysis (Orpheu for example) probab
<li>sv_rehlds_local_gametime &lt;1|0&gt; // A feature of local gametime which decrease "lags" if you run same map for a long time. Default: 0
<li>sv_use_entity_file // Use custom entity file for a map. Path to an entity file will be "maps/[map name].ent". 0 - use original entities. 1 - use .ent files from maps directory. 2 - use .ent files from maps directory and create new .ent file if not exist.
<li>sv_usercmd_custom_random_seed // When enabled server will populate an additional random seed independent of the client. Default: 0
<li>sv_net_incoming_decompression <1|0> // When enabled server will decompress of incoming compressed file transfer payloads. Default: 1
<li>sv_net_incoming_decompression_max_ratio <0|100> // Sets the max allowed ratio between compressed and uncompressed data for file transfer. (A ratio close to 90 indicates large uncompressed data with low entropy) Default: 80.0
<li>sv_net_incoming_decompression_max_size <16|65536> // Sets the max allowed size for decompressed file transfer data. Default: 65536 bytes
<li>sv_net_incoming_decompression_punish // Time in minutes for which the player will be banned for malformed/abnormal bzip2 fragments (0 - Permanent, use a negative number for a kick). Default: -1
<li>sv_tags &lt;comma-delimited string list of tags&gt; // Sets a string defining the "gametags" for this server, this is optional, but if it is set it allows users/scripts to filter in the matchmaking/server-browser interfaces based on the value. Default: ""
</ul>
</details>

99
rehlds/engine/net_chan.cpp
View File

@ -36,6 +36,12 @@ cvar_t net_showpackets = { "net_showpackets", "0", 0, 0.0f, nullptr};
cvar_t net_showdrop = { "net_showdrop", "0", 0, 0.0f, nullptr};
cvar_t net_drawslider = { "net_drawslider", "0", 0, 0.0f, nullptr};
cvar_t net_chokeloopback = { "net_chokeloop", "0", 0, 0.0f, nullptr};
cvar_t sv_net_incoming_decompression = { "sv_net_incoming_decompression", "1", 0, 1.0f, nullptr };
cvar_t sv_net_incoming_decompression_max_ratio = { "sv_net_incoming_decompression_max_ratio", "75.0", 0, 75.0f, nullptr };
cvar_t sv_net_incoming_decompression_max_size = { "sv_net_incoming_decompression_max_size", "65536", 0, 65536.0f, nullptr };
cvar_t sv_net_incoming_decompression_punish = { "sv_net_incoming_decompression_punish", "-1", 0, -1.0f, NULL };
cvar_t sv_filetransfercompression = { "sv_filetransfercompression", "1", 0, 0.0f, nullptr};
cvar_t sv_filetransfermaxsize = { "sv_filetransfermaxsize", "10485760", 0, 0.0f, nullptr};
@ -1433,6 +1439,9 @@ qboolean Netchan_CopyNormalFragments(netchan_t *chan)
p = chan->incomingbufs[FRAG_NORMAL_STREAM];
chan->incomingbufs[FRAG_NORMAL_STREAM] = nullptr;
chan->incomingready[FRAG_NORMAL_STREAM] = FALSE;
SZ_Clear(&net_message);
MSG_BeginReading();
@ -1470,27 +1479,87 @@ qboolean Netchan_CopyNormalFragments(netchan_t *chan)
}
SZ_Clear(&net_message);
chan->incomingbufs[FRAG_NORMAL_STREAM] = nullptr;
chan->incomingready[FRAG_NORMAL_STREAM] = FALSE;
return FALSE;
}
#endif // REHLDS_FIXES
qboolean success = TRUE;
if (*(uint32 *)net_message.data == MAKEID('B', 'Z', '2', '\0'))
{
// Determine whether decompression of compressed data is allowed
#ifdef REHLDS_FIXES
if (!sv_net_incoming_decompression.value)
{
if (chan->player_slot == 0)
{
Con_DPrintf("Incoming compressed data disallowed from\n");
return FALSE;
}
// compressed data is expected only after requesting resource list
else if (host_client->m_sendrescount == 0)
{
Con_DPrintf("%s:Incoming compressed data disallowed from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
return FALSE;
}
}
#endif
char uncompressed[65536];
unsigned int uncompressedSize = 65536;
BZ2_bzBuffToBuffDecompress(uncompressed, &uncompressedSize, (char*)net_message.data + 4, net_message.cursize - 4, 1, 0);
Q_memcpy(net_message.data, uncompressed, uncompressedSize);
net_message.cursize = uncompressedSize;
unsigned int uncompressedSize = clamp((int)sv_net_incoming_decompression_max_size.value, 16, 65536); // valid range (16 - 65536) bytes
unsigned int compressedSize = net_message.cursize - 4;
// Decompress net buffer data
if (success && (BZ2_bzBuffToBuffDecompress(uncompressed, &uncompressedSize, (char *)net_message.data + 4, compressedSize, 1, 0) == BZ_OK))
{
#ifdef REHLDS_FIXES
// Check for an abnormal size ratio between compressed and uncompressed data
if (sv_net_incoming_decompression_max_ratio.value > 0 && compressedSize < uncompressedSize)
{
float ratio = ((float)(uncompressedSize - compressedSize) / uncompressedSize) * 100.0f;
if (ratio >= sv_net_incoming_decompression_max_ratio.value)
{
if (chan->player_slot == 0)
Con_DPrintf("Incoming abnormal uncompressed size with ratio %.2f\n", ratio);
else
Con_DPrintf("%s:Incoming abnormal uncompressed size with ratio %.2f from %s\n", NET_AdrToString(chan->remote_address), ratio, host_client->name);
success = FALSE;
}
}
#endif
// Copy uncompressed data back to the net buffer
Q_memcpy(net_message.data, uncompressed, uncompressedSize);
net_message.cursize = uncompressedSize;
}
else
{
// malformed data or compressed data exceeding sv_net_incoming_decompression_max_size
success = FALSE;
}
// Drop client if decompression was unsuccessful
if (!success)
{
if ((chan->player_slot - 1) == host_client - g_psvs.clients)
{
#ifdef REHLDS_FIXES
if (sv_net_incoming_decompression_punish.value >= 0)
{
Con_DPrintf("%s:Banned for malformed/abnormal bzip2 fragments from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
Cbuf_AddText(va("addip %.1f %s\n", sv_net_incoming_decompression_punish.value, NET_BaseAdrToString(chan->remote_address)));
}
#endif
SV_DropClient(host_client, FALSE, "Malformed/abnormal compressed data");
}
SZ_Clear(&net_message);
}
}
chan->incomingbufs[FRAG_NORMAL_STREAM] = nullptr;
chan->incomingready[FRAG_NORMAL_STREAM] = FALSE;
return TRUE;
return success;
}
qboolean Netchan_CopyFileFragments(netchan_t *chan)
@ -1826,6 +1895,12 @@ void Netchan_Init(void)
Cvar_RegisterVariable(&net_chokeloopback);
Cvar_RegisterVariable(&net_drawslider);
Cvar_RegisterVariable(&sv_filetransfercompression);
#ifdef REHLDS_FIXES
Cvar_RegisterVariable(&sv_net_incoming_decompression);
Cvar_RegisterVariable(&sv_net_incoming_decompression_max_ratio);
Cvar_RegisterVariable(&sv_net_incoming_decompression_max_size);
Cvar_RegisterVariable(&sv_net_incoming_decompression_punish);
#endif
Cvar_RegisterVariable(&sv_filetransfermaxsize);
}