Files
UA-.NETStandard/fuzzing/Opc.Ua.PubSub.Fuzz.Tools/PubSub.Testcases.cs
romanett ce88955f70 Harden encoders/decoders against untrusted input and align them with Part 6 / Part 14 (#4599)
# Description

Hardens the encoders and decoders against untrusted input and aligns
them with OPC 10000-6 (1.05) and OPC 10000-14. This comes from an audit
of every codec reachable from a peer:
- Binary, JSON and XML decoders and encoders;
- built-in and complex types;
- UA-TCP/UASC framing;
- PubSub UADP and PubSub JSON.

The audit found 97 issues: 1 critical, 7 high, 39 medium and 50 low.
They are all fixed here, one commit per finding (IDs B1-, J1-, X1-, T1-,
S1-, U1-, P1-, E1-, E2- in the commit subjects). Every fix was then
checked against the spec a second time, and the deviations that re-check
found were fixed as well (`*-spec` commits).

## Security (decoders reachable from unauthenticated peers)

- **Allocation from length prefixes (B1-1, B1-5, U1-1, U1-3).**
- Array, string and byte-string lengths are checked against the bytes
left in the message before anything is allocated.
- Arrays read element by element grow as elements are decoded, so nested
length prefixes can no longer multiply memory.
- UADP discovery counts and chunk reassembly buffers are bounded the
same way.
- **Stack exhaustion.** Nesting is checked for remaining stack
(`RuntimeHelpers.EnsureSufficientExecutionStack` mapped to
`BadEncodingLimitsExceeded`), and the large Variant read/write methods
were split into scalar, array and matrix methods. Measured on 1 MB and
256 KB threads, no codec overflows at the default limits any more.
- **XML element depth (X1-1).** XmlElement values and raw
ExtensionObject bodies are copied node by node with a depth limit,
instead of with the recursive `InnerXml`, `ImportNode`, `InnerText` and
`DeepEquals` calls.
- **Limit bypasses:**
- JSON NodeId, QualifiedName and opaque strings now respect
MaxStringLength and MaxByteStringLength (J1-1).
  - Matrix rank is limited to 32.
  - Decimal size is bounded (T1-3).
  - XML base64 is checked before it is decoded.
  - XML arrays are checked before each element is read.
- **CPU and algorithmic cost:**
- UADP reassembly uses an O(1) overlap check with a per-message chunk
cap (U1-2).
  - PubSub JSON matches fields to metadata through a name index (P1-2).
  - LocalizedText "mul" text is parsed lazily (T1-5).
- Unknown SecurityTokenIds trigger a throttled background SKS refresh
instead of an inline call per datagram (U1-9).
- **PubSub metadata poisoning (P1-1).** Inbound metadata is registered
only for identities a configured reader expects, is capped, and an
unauthenticated message can no longer pin a version.
- **Exception contract.** Decoders fail with `ServiceResultException`
(BadDecodingError / BadEncodingLimitsExceeded) instead of letting
ArgumentException, InvalidOperationException, TypeLoadException and
similar escape.
- **UASC (S1-*):**
  - OPN and CLO must be single final chunks.
  - The certificate of an unsigned OPN is ignored.
  - The padding and ExtraPadding bytes are validated.
- A renewed token is activated only after a chunk has been verified with
it.
- A policy change on renewal is rejected before the channel certificate
is touched.
  - Secured chunk length arithmetic is bounded.

## Wire-visible behaviour changes

All follow the spec exactly; there is no reader for the old forms unless
noted.

- **UA Binary:**
  - Variant type ids 26-31 decode as ByteString.
- Picoseconds without their timestamp are ignored, and values of 10000
and above are clamped to 9999.
- A Null-type Variant with the array flag consumes its length and
dimensions.
- **UA JSON:**
- Messages are ExtensionObjects with the body inline; there is no
`UaBody` envelope any more (5.4.9 / 5.4.2.16).
- The Variant `Value` is omitted exactly for NULLs of nullable types
(Table 41).
  - RawData keeps nested UaType/UaTypeId and the StatusCode Symbol.
  - Duplicate member names are rejected.
  - `{}` decodes as a null ExtensionObject.
- Numbers and identifiers are parsed strictly and culture-independently.
  - QualifiedName follows 5.4.2.14.
  - Opaque bodies of known types carry the DataType id.
  - Enumerations without a literal are written as the number.
- **UA XML:**
  - The earliest DateTime is written as `0001-01-01T00:00:00Z`.
- Null typed scalars and null array elements are written with `xsi:nil`.
  - An ExtensionObject without a body has no `Body` element.
  - Strings XML cannot represent are rejected.
- Only the xs:dateTime and xs:date forms are accepted; a value without a
zone is still read as UTC, because published model files use it.
  - Only the Part 6 Guid form is accepted.
  - Booleans are case-sensitive in XmlDecoder.
- **UA-TCP:**
- OPNC/OPNA/CLOC/CLOA fault the channel. Older releases that split a
long-chain OPN into chunks are rejected, so this needs a release note.
  - The sender truncates the certificate chain to fit a single chunk.
  - The received certificate chain is sized from the chunk size.
- Hello buffer sizes down to 1024 bytes are honoured; below that, an ERR
with Bad_TcpInternalError is sent.
- A 4096-byte Error reason is accepted, and the SecurityPolicyUri limit
is 255 bytes.
- **PubSub UADP:**
- Chunk NetworkMessages use the Part 14 7.2.4.4.4 layout, and each chunk
is secured on its own with its own sequence number.
  - The Sizes array is part of the secured payload.
- Padded RawData keeps its length prefix, and null values are written as
-1.
  - DataSetMessages with the valid bit clear are skipped.
  - Null discovery arrays are accepted.
- **PubSub JSON:**
- Variants use `UaType`/`Value`, with the 7.2.5.4.2 top-level collapse.
The deprecated `Type`/`Body` form is still read.
- Status is written as a `{Code,Symbol}` object; a numeric Status is
still accepted.
  - Discovery messages follow Tables 188-192, with GUID MessageIds.
  - Enumeration fields are written as `Name_Value`.
  - Fields appended with a MinorVersion bump are accepted.

## Known deviations and limitations (documented, not changed)

- A known type whose ExtensionObject XML body fails to decode fails the
message, like a failing binary body. 5.2.2.15 only says the decoder
*should* continue, and continuing reopens the log-flooding path.
- Reserved Variant type ids 26-31 are passed to the application as
ByteString without the raw type id.
- JSON UaTypeId of an opaque body of an *unknown* type stays the
encoding id, because no type system is available to map it.
- PubSub JSON encoder:
- Structure fields without a subtype are still wrapped with a UaType,
and concrete multi-dimensional or abstract-rank fields still carry a
UaType (Table 186).
- Namespace-0 enumerations without EnumDataTypes are written as a
numeric string.
- Chunked transcoded frames have no writer group, so their sequence
numbers continue from the source number.
- Pre-existing and out of scope: the HTTPS JSON binding uses
Content-Type `application/opcua+uajson`, while 1.05 7.4.5 requires
`application/json`.

## Tests

- Every fix has a regression test.
- Tests that pinned non-conformant behaviour were updated, and their
commit messages say so.
- Fuzz seeds were regenerated where the wire changed.

Local results:
net10.0, 27 suites green (Types 11354, Core.Encoders 2933, Encoders.Fuzz
8112, Core 5955 + 1 known intermittent ActivityTraceFlags metrics test
that passes alone, Client 2732, Server 7802, Sessions 790, GDS 1234,
Subscriptions 641, SourceGeneration.Core 4266, PubSub 1490 and all
PubSub transport suites). Full UA.slnx build 0 warnings / 0 errors on
net10.0 and net48.

## Related Issues

- Follow-up: #4598 (possible throughput regression of per-element binary
array reads).

## Checklist

- [x] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf)
and read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [x] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added all necessary documentation.
- [x] I have verified that my changes do not introduce (new) build or
analyzer warnings.
- [ ] I ran **all** tests locally using the **UA.slnx** solution against
at least .net **framework** and .net **10**, and all passed. (net10.0
suites run; net48 build only)
- [ ] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [ ] I have addressed **all** PR feedback received.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-01 05:12:47 +00:00

191 lines
9.0 KiB
C#

/* ========================================================================
* Copyright (c) 2005-2026 The OPC Foundation, Inc. All rights reserved.
*
* OPC Foundation MIT License 1.00
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* The complete license agreement can be found here:
* http://opcfoundation.org/License/MIT/1.00/
* ======================================================================*/
using System;
using System.Collections.Generic;
using System.IO;
using System.Text.Json;
using Opc.Ua.PubSub.Encoding;
using Opc.Ua.PubSub.Encoding.Json;
using Opc.Ua.PubSub.Encoding.Uadp;
namespace Opc.Ua.Fuzzing
{
public static partial class Testcases
{
public static void Run(string workPath, ITelemetryContext telemetry)
{
ArgumentException.ThrowIfNullOrWhiteSpace(workPath);
_ = telemetry;
foreach ((string bucket, string name, byte[] data) in CreatePubSubSeeds())
{
string directory = workPath + "." + bucket;
Directory.CreateDirectory(directory);
File.WriteAllBytes(Path.Combine(directory, name), data);
}
}
internal static IEnumerable<(string Bucket, string Name, byte[] Data)> CreatePubSubSeeds()
{
yield return ("Json", "metadata-keyframe-verbose.json", CreateJsonSeed(JsonEncodingMode.Verbose));
yield return ("Json", "metadata-keyframe-compact.json", CreateJsonSeed(JsonEncodingMode.Compact));
yield return ("Json", "metadata-keyframe-raw.json", CreateJsonSeed(JsonEncodingMode.RawData));
yield return ("Json", "metadata-keyframe-datavalue.json",
CreateJsonSeed(JsonEncodingMode.Verbose, PubSubFieldEncoding.DataValue));
yield return ("Uadp", "metadata-keyframe-variant.uadp", CreateUadpSeed(PubSubFieldEncoding.Variant));
yield return ("Uadp", "metadata-keyframe-datavalue.uadp", CreateUadpSeed(PubSubFieldEncoding.DataValue));
byte[] rawData = CreateUadpSeed(PubSubFieldEncoding.RawData);
yield return ("Uadp", "metadata-keyframe-raw.uadp", rawData);
var chunker = new UadpChunker();
yield return ("Chunks", "metadata-keyframe-complete.bin",
chunker.Split(rawData, 42, rawData.Length + UadpChunker.ChunkHeaderSize)[0]);
IReadOnlyList<byte[]> chunks = chunker.Split(rawData, 42, 42);
for (int i = 0; i < chunks.Count; i++)
{
yield return ("Chunks", FormattableString.Invariant($"metadata-keyframe-chunk-{i:000}.bin"), chunks[i]);
}
}
internal static byte[] CreateJsonSeed(
JsonEncodingMode mode,
PubSubFieldEncoding fieldEncoding = PubSubFieldEncoding.Variant)
{
using var stream = new MemoryStream();
using (var writer = new Utf8JsonWriter(stream))
{
writer.WriteStartObject();
writer.WriteString("MessageId", FormattableString.Invariant($"retained-{mode}-{fieldEncoding}"));
writer.WriteString("MessageType", "ua-data");
writer.WriteString("PublisherId", "300");
writer.WriteString("DataSetClassId", FuzzableCode.SeedDataSetClassId.ToString());
writer.WriteStartArray("Messages");
writer.WriteStartObject();
writer.WriteNumber("DataSetWriterId", 1);
writer.WriteNumber("SequenceNumber", 42);
writer.WriteString("MessageType", "ua-keyframe");
writer.WriteString("Timestamp", FuzzableCode.SeedTime);
writer.WriteStartObject("MetaDataVersion");
writer.WriteNumber("MajorVersion", 1);
writer.WriteNumber("MinorVersion", 2);
writer.WriteEndObject();
// Verbose fields with a concrete FieldMetaData type are collapsed to
// bare values (Part 14 §7.2.5.4.2); encode the Verbose seed without
// metadata so it keeps exercising the UaType/Value Variant envelope.
JsonFieldEncoder.EncodeFields(
writer,
CreateFields(fieldEncoding),
mode == JsonEncodingMode.Verbose ? null : FuzzableCode.CreateMetaData(),
mode,
FuzzableCode.NewContext().MessageContext);
writer.WriteEndObject();
writer.WriteEndArray();
writer.WriteEndObject();
}
return stream.ToArray();
}
internal static byte[] CreateUadpSeed(PubSubFieldEncoding fieldEncoding)
{
return UadpEncoder.EncodeData(CreateUadpMessage(fieldEncoding), FuzzableCode.NewContext());
}
internal static UadpNetworkMessage CreateUadpMessage(PubSubFieldEncoding fieldEncoding)
{
DataSetMetaDataType metaData = FuzzableCode.CreateMetaData();
return new UadpNetworkMessage
{
ContentMask =
UadpNetworkMessageContentMask.PublisherId |
UadpNetworkMessageContentMask.GroupHeader |
UadpNetworkMessageContentMask.WriterGroupId |
UadpNetworkMessageContentMask.PayloadHeader |
UadpNetworkMessageContentMask.SequenceNumber |
UadpNetworkMessageContentMask.DataSetClassId |
UadpNetworkMessageContentMask.Timestamp,
PublisherId = FuzzableCode.SeedPublisherId,
WriterGroupId = 1,
SequenceNumber = 42,
DataSetClassId = FuzzableCode.SeedDataSetClassId,
Timestamp = new DateTimeUtc(FuzzableCode.SeedTime),
MetaData = metaData,
DataSetMessages =
[
new UadpDataSetMessage
{
ContentMask =
UadpDataSetMessageContentMask.SequenceNumber |
UadpDataSetMessageContentMask.MajorVersion |
UadpDataSetMessageContentMask.MinorVersion |
UadpDataSetMessageContentMask.Timestamp,
DataSetWriterId = 1,
SequenceNumber = 42,
MessageType = PubSubDataSetMessageType.KeyFrame,
FieldEncoding = fieldEncoding,
FieldContentMask =
DataSetFieldContentMask.StatusCode |
DataSetFieldContentMask.SourceTimestamp |
DataSetFieldContentMask.ServerTimestamp |
DataSetFieldContentMask.SourcePicoSeconds |
DataSetFieldContentMask.ServerPicoSeconds,
MetaDataVersion = metaData.ConfigurationVersion,
Timestamp = new DateTimeUtc(FuzzableCode.SeedTime),
Fields = CreateFields(fieldEncoding)
}
]
};
}
internal static ArrayOf<DataSetField> CreateFields(PubSubFieldEncoding encoding)
{
return
[
CreateField("Running", Variant.From(true), encoding),
CreateField("Count", Variant.From(42), encoding) with { StatusCode = StatusCodes.Uncertain },
CreateField("Temperature", Variant.From(21.5), encoding),
CreateField("Label", Variant.From("pubsub"), encoding)
];
}
private static DataSetField CreateField(string name, Variant value, PubSubFieldEncoding encoding)
{
return new DataSetField
{
Name = name,
Value = value,
Encoding = encoding,
SourceTimestamp = new DateTimeUtc(FuzzableCode.SeedTime),
ServerTimestamp = new DateTimeUtc(FuzzableCode.SeedTime.AddSeconds(1)),
SourcePicoSeconds = 10,
ServerPicoSeconds = 20
};
}
}
}