mirror of
https://github.com/OPCFoundation/UA-.NETStandard.git
synced 2026-10-16 21:02:51 +08:00
romanett
ce88955f70
# 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>