forked from PaperMC/Waterfall
-
Notifications
You must be signed in to change notification settings - Fork 0
/
0058-Additional-DoS-mitigations.patch
245 lines (235 loc) · 11.7 KB
/
0058-Additional-DoS-mitigations.patch
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
From a46065c54e536379cf3328642e23e03092dd9691 Mon Sep 17 00:00:00 2001
From: "Five (Xer)" <[email protected]>
Date: Sat, 30 Jan 2021 18:04:14 +0100
Subject: [PATCH] Additional DoS mitigations
Some stricter length checks and cached exceptions to withstand more illegitimate connections
Courtesy of Tux and the Velocity Contributors. See:
https://github.com/VelocityPowered/Velocity/commit/5ceac16a821ea35572ff11412ace8929fd06e278
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java b/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java
index d10cf2ed..31a95495 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java
@@ -44,6 +44,7 @@ public abstract class DefinedPacket
int len = readVarInt( buf );
if ( len > maxLen * 4 )
{
+ if(!MinecraftDecoder.DEBUG) throw STRING_TOO_MANY_BYTES_EXCEPTION; // Waterfall start: Additional DoS mitigations
throw new OverflowPacketException( String.format( "Cannot receive string longer than %d (got %d bytes)", maxLen * 4, len ) );
}
@@ -53,6 +54,7 @@ public abstract class DefinedPacket
String s = new String( b, Charsets.UTF_8 );
if ( s.length() > maxLen )
{
+ if(!MinecraftDecoder.DEBUG) throw STRING_TOO_LONG_EXCEPTION; // Waterfall start: Additional DoS mitigations
throw new OverflowPacketException( String.format( "Cannot receive string longer than %d (got %d characters)", maxLen, s.length() ) );
}
@@ -284,4 +286,21 @@ public abstract class DefinedPacket
@Override
public abstract String toString();
+
+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
+ private static final OverflowPacketException STRING_TOO_LONG_EXCEPTION
+ = new OverflowPacketException("A string was longer than allowed. For more "
+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
+ private static final OverflowPacketException STRING_TOO_MANY_BYTES_EXCEPTION
+ = new OverflowPacketException("A string had more data than allowed. For more "
+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
+
+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ return -1;
+ }
+
+ public int expectedMinLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ return 0;
+ }
+ // Waterfall end
}
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java b/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
index 37d28c01..01d35f41 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
@@ -3,7 +3,7 @@ package net.md_5.bungee.protocol;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.channel.ChannelHandlerContext;
-import io.netty.handler.codec.DecoderException;
+import io.netty.handler.codec.CorruptedFrameException;
import io.netty.handler.codec.MessageToMessageDecoder;
import java.util.List;
import lombok.AllArgsConstructor;
@@ -56,10 +56,16 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
if ( packet != null )
{
packetTypeInfo = packet.getClass();
+ doLengthSanityChecks(in, packet, prot.getDirection(), packetId); // Waterfall: Additional DoS mitigations
packet.read( in, prot.getDirection(), protocolVersion );
if ( in.isReadable() )
{
+ // Waterfall start: Additional DoS mitigations
+ if(!DEBUG) {
+ throw PACKET_NOT_READ_TO_END;
+ }
+ // Waterfall end
throw new BadPacketException( "Did not read all bytes from packet " + packet.getClass() + " " + packetId + " Protocol " + protocol + " Direction " + prot.getDirection() );
}
} else
@@ -70,6 +76,11 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
out.add( new PacketWrapper( packet, slice ) );
slice = null;
} catch (BadPacketException | IndexOutOfBoundsException e) {
+ // Waterfall start: Additional DoS mitigations
+ if(!DEBUG) {
+ throw e;
+ }
+ // Waterfall end
final String packetTypeStr;
if (packetTypeInfo instanceof Integer) {
packetTypeStr = "id " + Integer.toHexString((Integer) packetTypeInfo);
@@ -87,4 +98,52 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
}
}
}
+
+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
+ public static final boolean DEBUG = Boolean.getBoolean("waterfall.packet-decode-logging");
+
+ // Cached Exceptions:
+ private static final CorruptedFrameException PACKET_LENGTH_OVERSIZED =
+ new CorruptedFrameException("A packet could not be decoded because it was too large. For more "
+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
+ private static final CorruptedFrameException PACKET_LENGTH_UNDERSIZED =
+ new CorruptedFrameException("A packet could not be decoded because it was smaller than allowed. For more "
+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
+ private static final BadPacketException PACKET_NOT_READ_TO_END =
+ new BadPacketException("Couldn't read all bytes from a packet. For more "
+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
+
+
+ private void doLengthSanityChecks(ByteBuf buf, DefinedPacket packet,
+ ProtocolConstants.Direction direction, int packetId) throws Exception {
+ int expectedMinLen = packet.expectedMinLength(buf, direction, protocolVersion);
+ int expectedMaxLen = packet.expectedMaxLength(buf, direction, protocolVersion);
+ if (expectedMaxLen != -1 && buf.readableBytes() > expectedMaxLen) {
+ throw handleOverflow(packet, expectedMaxLen, buf.readableBytes(), packetId);
+ }
+ if (buf.readableBytes() < expectedMinLen) {
+ throw handleUnderflow(packet, expectedMaxLen, buf.readableBytes(), packetId);
+ }
+ }
+
+ private Exception handleOverflow(DefinedPacket packet, int expected, int actual, int packetId) {
+ if (DEBUG) {
+ throw new CorruptedFrameException( "Packet " + packet.getClass() + " " + packetId
+ + " Protocol " + protocolVersion + " was too big (expected "
+ + expected + " bytes, got " + actual + " bytes)");
+ } else {
+ return PACKET_LENGTH_OVERSIZED;
+ }
+ }
+
+ private Exception handleUnderflow(DefinedPacket packet, int expected, int actual, int packetId) {
+ if (DEBUG) {
+ throw new CorruptedFrameException( "Packet " + packet.getClass() + " " + packetId
+ + " Protocol " + protocolVersion + " was too small (expected "
+ + expected + " bytes, got " + actual + " bytes)");
+ } else {
+ return PACKET_LENGTH_UNDERSIZED;
+ }
+ }
+ // Waterfall end
}
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java
index 388f6cdb..53575ce0 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java
@@ -38,4 +38,16 @@ public class EncryptionResponse extends DefinedPacket
{
handler.handle( this );
}
+
+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ // It turns out these come out to the same length, whether we're talking >=1.8 or not.
+ // The length prefix always winds up being 2 bytes.
+ return 260;
+ }
+
+ public int expectedMinLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ return expectedMaxLength(buf, direction, protocolVersion);
+ }
+ // Waterfall end
}
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java
index 08ee376e..cfd8e64e 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java
@@ -7,6 +7,7 @@ import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import net.md_5.bungee.protocol.AbstractPacketHandler;
import net.md_5.bungee.protocol.DefinedPacket;
+import net.md_5.bungee.protocol.ProtocolConstants;
@Data
@NoArgsConstructor
@@ -34,4 +35,12 @@ public class LoginRequest extends DefinedPacket
{
handler.handle( this );
}
+
+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ // Accommodate the rare (but likely malicious) use of UTF-8 usernames, since it is technically
+ // legal on the protocol level.
+ return 1 + (16 * 4);
+ }
+ // Waterfall end
}
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java
index 5f24d425..3163a771 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java
@@ -7,6 +7,7 @@ import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import net.md_5.bungee.protocol.AbstractPacketHandler;
import net.md_5.bungee.protocol.DefinedPacket;
+import net.md_5.bungee.protocol.ProtocolConstants;
@Data
@NoArgsConstructor
@@ -34,4 +35,14 @@ public class PingPacket extends DefinedPacket
{
handler.handle( this );
}
+
+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ return 8;
+ }
+
+ public int expectedMinLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ return 8;
+ }
+ // Waterfall end
}
diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java
index 738f0c92..ec33d337 100644
--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java
+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java
@@ -6,6 +6,7 @@ import lombok.EqualsAndHashCode;
import lombok.NoArgsConstructor;
import net.md_5.bungee.protocol.AbstractPacketHandler;
import net.md_5.bungee.protocol.DefinedPacket;
+import net.md_5.bungee.protocol.ProtocolConstants;
@Data
@NoArgsConstructor
@@ -28,4 +29,10 @@ public class StatusRequest extends DefinedPacket
{
handler.handle( this );
}
+
+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
+ return 0;
+ }
+ // Waterfall end
}
--
2.32.0