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fix(sdk): bound zip64 reader offsets against the archive (DSPX-4590) - #4043
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Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review. 📝 WalkthroughWalkthroughThe ZIP reader now validates disk-derived offsets and sizes against archive and central-directory boundaries. It stores checked entry data ranges, bounds read indexes, and adds conformance and fuzz tests for forged ZIP64 metadata. ChangesZIP stream validation
Priority: ⬇️ Low Estimated code review effort: 3 (Moderate) | ~25 minutes Change: Bug fix Merge Risk: 🟡 Moderate · up to Malformed archives can still have records outside their declared central directory accepted. Resolve or explicitly accept this remaining validation gap before merging. Security Architecture ReviewSecurity architecture risk: 🔵 Low · up to The change strengthens validation of untrusted archives. No introduced or worsened security issue was identified in the reviewed paths, but malformed-directory handling and concurrent-use guarantees remain incompletely established. Retained concerns Security review detailsSecurity Blast Radius
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In `@sdk/internal/zipstream/reader.go`:
- Around line 167-178: Update the central-directory parsing around within and
the entryCount loop to compute the declared central-directory end from
SizeOfCentralDirectory or CentralDirectorySize, validate that end against the
applicable trailer position, and use it instead of archiveSize when bounding
entryCount and cdEntryStart. Ensure parsing cannot consume bytes beyond the
declared central-directory region while preserving valid archive handling.
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sdk/internal/zipstream/fuzz_test.gosdk/internal/zipstream/reader.gosdk/internal/zipstream/zip64_conformance_test.go
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…4087) Jira: https://virtru.atlassian.net/browse/DSPX-4590 The read-side counterpart to opentdf#3936, which fixed the same class of bug on the write side. Independent of every open stack — no PR in DSPX-2604 (opentdf#3941, opentdf#3943-opentdf#3949) touches `sdk/internal/zipstream`, and opentdf#4043 leaves `readBytes` alone — so this sits directly on `main` and can land in any order. ## The bug `readBytes` issued a single `Read` and, on the nil-error path, returned the whole `make()`'d buffer regardless of how many bytes actually arrived: ```go buf := make([]byte, size) n, err := readerSeeker.Read(buf) if errors.Is(err, io.EOF) { return buf[:n], io.EOF } if err != nil { return buf[:n], ... } return buf, nil // full length, zero-padded, n discarded ``` `io.Reader` explicitly permits `0 < n < len(p)` with a nil error, so the tail of the buffer comes back as zeros that never existed in the archive — reported as success. Demonstrated against a valid fixture with a one-byte-at-a-time `ReadSeeker`: ``` want "payload bytes" got "p\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" err=<nil> len=13 ``` `bytes.Reader` never reads short, which is why no existing test caught it. But `NewReader` takes a caller-supplied `io.ReadSeeker`, and the implementations that *do* read short in practice — HTTP range requests, network filesystems — are exactly the ones large archives get served from. The `ErrSegSizeMismatch` guard in `tdf.go` (`sdk/tdf.go:1114`) cannot catch this either: `make()` already gave the buffer the length that check is looking for, so the check is comparing a value that is correct by construction. A silently zero-padded segment reaches AES-GCM and fails there instead, several layers from the cause. ## Why this is the same fix as opentdf#3936 opentdf#3936 ("fill each segment with io.ReadFull and size the buffer to the input") made this argument for `CreateTDFContext`'s encrypt loop: > io.Reader.Read is permitted to return fewer bytes than the caller asked for > without erroring… A `*bytes.Reader` or `*os.File` on a local disk rarely > returns short, which is why this has held up, but any wrapping ReadSeeker — > a decompressor, a network-backed store, an instrumented reader — can > trigger it and there is nothing wrong with the input when it does. Same defect, opposite consequence. On the write side a short read made the loop *fail loudly* on valid input (`io.ReadSeeker.Read size mismatch`). Here it *silently corrupts*: no error, full-length buffer, invented bytes. The noisy direction got fixed; the quiet one was left, and it is the worse of the two. This closes it. ## The fix `io.ReadFull`, which retries the short read and reports `io.ErrUnexpectedEOF` when the archive really is truncated. Two related changes follow from it: - **No data is returned alongside an error.** The old code handed back a partial buffer with a bare `io.EOF` — a trap for a caller doing the reflexive `errors.Is(err, io.EOF)` → "normal end of stream", which would silently accept a truncated payload. All four production callers (`sdk.go:489`, `tdf.go:864`, `tdf.go:987`, `tdf.go:1109`) already treat the error as fatal, so nothing depends on the old shape. - **`io.EOF` is normalized to `io.ErrUnexpectedEOF`.** `io.ReadFull` reports the bare sentinel when it reads *nothing* — a read starting exactly at the end of a truncated archive — and `io.ErrUnexpectedEOF` only when it got part of the request. Both mean the same thing to a caller that asked for a byte count taken from the central directory, and letting the first one out would have reopened the trap above. Zero-length reads are unaffected; `io.ReadFull` returns nil for them even at EOF. (Thanks @opencode for catching this.) - **A zero-length read at the end of the archive now succeeds.** Any `Read` on an exhausted `bytes.Reader` reports `io.EOF`, including a zero-length one, so an empty entry stored last used to fail to read back. Error *classification* is deliberately left alone — `readBytes` still does not wrap `errZipFormat`. Eight other sites in this file have the same issue and that belongs in one follow-up, not here. ## Reading this next to opentdf#3945 opentdf#3945 goes the other way on the same sentinel: it makes the encrypt loop *tolerate* `io.EOF` and `io.ErrUnexpectedEOF` from `io.ReadFull`, while this PR makes `io.ErrUnexpectedEOF` fatal. Both are right, because the contracts differ. The write side has no declared length — a short final read just means the caller's stream ended. The read side has a length from the central directory, so a short read means the archive is truncated. The zero-length change above is also the mirror of opentdf#3945's empty-payload handling ("An empty payload still gets one empty segment"). `zeroLenOKReader` in `tdf_segment_defaults_test.go` exists because `SDK.CreateTDF` cannot currently encrypt a genuinely empty `io.Reader`; opentdf#3945 fixes the write half and this fixes the read half. Worth rechecking whether that workaround can be deleted once both have landed — not assuming it, since the comment there describes more than one quirk. ## Tests `chunkedSeeker` in `reader_test.go` serves at most N bytes per `Read` and reports no error for the short ones, standing in for the range-backed reader `bytes.Reader` cannot model. Five cases: short reads reassembled, a partially satisfiable read rejected with `io.ErrUnexpectedEOF` and no partial buffer, a read starting at EOF rejected with the same sentinel rather than `io.EOF`, a zero-length read at EOF succeeding, and the same short read driven end-to-end through `ReadAllFileData`. Each was verified to **fail against the implementation it guards** — the first four against the original `readBytes`, the EOF-normalization case against this PR with the conversion removed — so they are regression tests rather than tautologies. They use testify, unlike the rest of `reader_test.go`, which is `t.Fatalf` throughout — the other three test files in the package use testify, and `require.ErrorIs(err, io.ErrUnexpectedEOF)` has no clean `t.Fatalf` form. Say the word if you would rather the file stay internally consistent. - `cd sdk && go test ./... -race` — green - `golangci-lint run ./internal/zipstream/...` — 0 issues - `make fmt` — no diff --------- Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
go-sdk's zip layer disagrees with the other SDKs in a handful of places. This addresses findings 1-6 from the DSPX-4590 investigation (finding 7, per-segment size defaults, is the parent PR this one is stacked on). ## Finding 1 (interop): writer switched to ZIP64 at 4 GiB instead of 2 GiB `Finalize` compared against `^uint32(0)`, so a payload between 2 GiB and 4 GiB was written as a zip32 archive with a value in the top half of the unsigned 32-bit range. java-sdk widens those central-directory fields *signed*, so deployed Java clients read the size/offset back as a negative number and cannot open the container. web-sdk always writes ZIP64, java-sdk (since java-sdk#393) switches at `Integer.MAX_VALUE`. - New `maxNonZip64Value = math.MaxInt32` in `zip_primitives.go`, mirroring java-sdk's `MAX_NON_ZIP64_VALUE`. - The rule is applied to the uncompressed size, the compressed size **and** `entry.Offset` (the local-header offset), which was previously not checked at all -- an archive under 2 GiB of payload could still place a later entry's header past the boundary. - The threshold is injectable: `Config.MaxNonZip64Value` plus a `WithMaxNonZip64Value` option (clamped to `(0, maxNonZip64Value]`, so it can only ever make the writer *more* eager to use ZIP64). This lets the tests drive the ZIP64 path with a 1 KiB threshold instead of allocating gigabytes. ## Finding 2: ZIP64 extra field parsed positionally The reader assumed the ZIP64 extended-information field was the first entry in the extra-field area and that all three values were always present. Per APPNOTE 4.5.3 the values appear in the order *original size, compressed size, local header offset*, and each is present **only** when its central-directory counterpart holds the `0xFFFFFFFF` sentinel. A container whose extra area leads with, say, an extended-timestamp field (tag `0x5455`) was misparsed. `parseZip64ExtraField` now walks the whole extra area, skips foreign tags, reads values in spec order gated on the sentinels, and rejects a field that claims to run past the end of the area. ## Finding 3: ZIP64 detected from the CD offset alone `NewReader` only looked at `CentralDirectoryOffset == 0xFFFFFFFF`. An archive that overflows the entry count (`0xFFFF`) or the central-directory size but not the offset was read as zip32. `eocdNeedsZip64` now checks all three EOCD sentinel fields. ## Finding 4: per-entry ZIP64 extra field ignored without a ZIP64 EOCD A writer may put a ZIP64 extra field on an individual entry while leaving the EOCD in zip32 form. The reader now consults the extra field whenever the central-directory header carries a sentinel, independent of the EOCD form. ## Finding 5: central-directory cursor could wrap at uint16 `nextCD` was advanced with uint16 arithmetic and did not include the file comment. A 65000-byte filename plus a 600-byte extra field wraps to 110 and the reader walks into the middle of a header. The advance is now done in uint64 and includes `FileCommentLength`. ## Finding 6: silent truncation when a value does not fit 32 bits The zip32 paths narrowed with a bare cast. `checkFitsInCentralDirectory` now returns a new `ErrFieldOverflow` for the compressed size, uncompressed size, local-header offset, central-directory size/offset and entry count instead of writing a corrupt archive. (With finding 1 in place this is unreachable in normal operation; it is a backstop against future callers.) ## Tests `sdk/internal/zipstream/zip64_conformance_test.go` -- hand-assembles raw zip archives (`buildRawZip`) so the reader can be pointed at containers no Go writer would produce: extra field not first, differing compressed and uncompressed sizes so the APPNOTE 4.5.3 ordering is actually asserted (a fixture with equal sizes passes either way), per-entry ZIP64 under a zip32 EOCD, a central-directory file comment, the 65646-byte name+extra case that wraps to 110 at uint16, ZIP64 implied by the entry count, and a malformed extra field. Writer side: `TestWriterSwitchesToZip64AtInjectedThreshold` uses the injected 1 KiB threshold, `TestEntryNeedsZip64AtTwoGiB` pins `maxNonZip64Value == math.MaxInt32` and covers size / compressed size / offset, `TestCentralDirectoryNarrowingGuard` covers finding 6. `sdk/internal/zipstream/fuzz_test.go` -- two new seeds for the `nextCD` overflow and the file-comment case. ## Follow-up required in opentdf/tests (NOT covered by this PR) > The xtest cell `test_tdfs.py::test_chunky_roundtrip` currently **SKIPS** for > go, because `xtest/sdk/go/cli.sh` answers no to `supports chunky`. That shim > lives in the `opentdf/tests` repo, so merging this PR does **not** flip it -- > the go column will stay skipped and the interop regression will stay > invisible in CI. When this fix ships in a release, someone needs to > version-gate the `chunky)` case in `xtest/sdk/go/cli.sh` so it reports > support at or above that version. Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
The zip reader took ZIP64 offsets and sizes straight off disk as uint64 and narrowed them to int64 without a check. A central directory entry carrying the 0xFFFFFFFF sentinel plus a ZIP64 extra field declaring a stored size of 1<<63 produced a negative entry length. ReadAllFileData only compares the length against maxSize, which a negative value passes, so readBytes then panicked in make([]byte, size). Those values are attacker-controlled in any TDF, and the existing fuzz harness walks exactly that path. Bound every disk-sourced position instead. The first Seek(-endOfCDRecordSize, io.SeekEnd) already yields the archive length for free, and since that came from an int64, a single comparison rules out both the above-MaxInt64 narrowing and a merely-past-EOF offset. This is the read-side counterpart to checkFitsInCentralDirectory, which already refuses to narrow a value into a 32-bit field on write. The checking is expressed as a `bound` type rather than a helper taking a run of same-typed uint64s, where swapping two arguments would be a silent security bug that still type-checks. A bound is a limit already known to fit in an int64; the only ways to obtain one are archiveBound, which derives it from a length the io.ReadSeeker reported, and narrow, which cannot widen. A raw uint64 read off disk cannot become a limit without passing through narrow, so the precondition that makes the int64 conversion safe is carried by the type instead of by an `if` a hundred lines away. Each bound also carries the name it appears under in error messages, so a correct check cannot report the wrong reason. Entry data is bounded by the start of the central directory, not the end of the archive. Stopping at EOF would still let a forged size swallow the central directory and the EOCD, and ReadAllFileData would hand that ZIP metadata back as file content. zipFileEntry is unexported and stays a signed pair: every consumer is signed, and uint64 storage would only move the narrowing into readBytes, where there is no archive length left to check against. Also bounds the ZIP64 entry count by the room the archive has, so a hostile count fails immediately rather than after billions of failed seeks. ## Tests zip64_conformance_test.go covers each bound separately, since seven guards now wrap errZipFormat and an errors.Is alone cannot tell which one fired: a central directory start past the archive (with a zero entry count, so the walk cannot mask the guard), a walk that leaves the archive mid-iteration (forged FileCommentLength), a local header inside the archive but past the central directory, local header lengths that overrun the central directory, and an io.ReadSeeker reporting an implausible position. The entry-count test asserts the short-circuit by counting Seeks rather than by the error value. TestReadFileDataBoundsIndex gained an interior read that actually checks the returned offset -- the shared fixture is filled with 0xFF, so a read at the wrong index compared equal -- plus the two missing length cases. fuzz_test.go derives the overrunning-size seed from the fixture instead of hard-coding 200, and fails if it no longer reaches past the central directory. The fuzz body now drives ReadFileData at the entry boundaries too. Every guard was mutation-tested: each one was broken in turn and confirmed to take a test down with it. Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
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Remove the 10 MB default manifest size cap from LoadTDF and IsValidTdf. DSPX-4502 targets 50 TiB payloads whose manifests exceed 1 GiB, and the default cap made default-config LoadTDF reject such legitimate TDFs. Memory scaling for very large manifests is tracked in DSPX-4905. The defence against hostile declared ZIP sizes is the archive bounds checking in zipstream.NewReader (#4043) plus the negative-length guards in ReadAllFileData/readBytes, not a size cap: a manifest entry declaring more bytes than the archive holds is still rejected before allocation. WithMaxManifestSize stays as an opt-in limit (it still requires a positive size). In zipstream, a zero or negative manifest limit, the new default, means no limit; ReadAllFileData's contract is unchanged. Behaviour change: callers that relied on the implicit 10 MB cap to bound memory must now pass WithMaxManifestSize explicitly. Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
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## Summary - Removes the 10 MB default manifest cap from the SDK reader (`defaultMaxManifestSize`) and from zipstream (`manifestMaxSize`). - DSPX-4502 targets payloads up to 50 TiB, whose manifests grow past 1 GiB (policy size plus per-segment entries). No fixed default can serve that, and it silently broke loading of large TDFs. - Forged ZIP sizes do not need a cap: `NewReader` already checks every declared size and offset against the archive bounds (DSPX-4590, #4043). - `WithMaxManifestSize(n)` stays as an opt-in memory bound; `n` must be > 0. `WithTDFManifestMaxSize` treats a non-positive size as no cap. ## Behaviour change `LoadTDF` and `IsValidTdf` now accept manifests over 10 MB by default. Callers that relied on the old default to bound memory on untrusted input should pass `WithMaxManifestSize`. Memory scaling of very large manifests is tracked separately in DSPX-4905. ## Testing - `Test_LargeManifest_WithMaxManifest`: an 11 MB manifest loads with default options; an explicit limit still rejects larger ones; `WithMaxManifestSize(0)` is an error. - `TestIsValidTdf_NoDefaultManifestSizeCap` and new zipstream `TDFReader` tests cover the default and opt-in paths. - `go test ./...` in `sdk` and `sdk/internal/zipstream`; `golangci-lint run ./...` in `sdk` shows no findings in touched files. Root `make lint` and `make test` not yet run. Split out of the DSPX-5102 hardening work; independent of #4212. <!-- This is an auto-generated comment: release notes by coderabbit.ai --> ## Summary by CodeRabbit * **New Features** * TDF manifests larger than 10 MiB can now be read and validated with default settings, provided they fit within the archive’s bounds. * Manifest size limits are now opt-in: configure a positive limit to cap the size. Zero or negative values do not impose an application-level limit. * **Bug Fixes** * Manifests within a configured positive limit remain accepted, while those exceeding it are rejected. <!-- end of auto-generated comment: release notes by coderabbit.ai --> Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
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…PX-5102) A ZIP64 stored size of 0xFFFFFFFFFFFFFFFF narrows to int64 -1, which would reach make([]byte, -1) (#4202). NewReader already rejects it because every ZIP64 size and offset is checked against the archive bounds (DSPX-4590, #4043), so there is no code change here. The existing conformance table covers 1<<63, which narrows to MinInt64. Add the exact MaxUint64 value, which narrows to -1, as a row and as a FuzzReader seed. Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
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…PX-5102) A ZIP64 stored size of 0xFFFFFFFFFFFFFFFF would narrow to int64 -1 and reach make([]byte, -1) (#4202). NewReader already rejects it because every ZIP64 size and offset is checked against the archive bounds (DSPX-4590, #4043), so there is no code change here. The bounds check is written as delta > limit-base. MaxUint64 is the value that wraps if it were ever rewritten as base+delta > limit; the other rows (1<<63, 1<<40) do not wrap, so they would not notice. Add MaxUint64 as a conformance row and as a FuzzReader seed. Both fail if the check is made additive. Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
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Follow-up to #3981.
Context
Reviewing #3981 raised the question of whether
ZipFileEntryshould be auint64pairinstead of a signed one.
It should not, and looking into it turned up a reachable panic that switching to
uint64would have hidden rather than fixed.The bug
NewReaderread ZIP64 offsets and sizes from disk asuint64and converted them toint64without checking them. Take a central directory entry with the0xFFFFFFFFsentinel and a ZIP64 extra field declaring a stored size of
1<<63. Line numbers are inthe pre-fix reader:
reader.go:173:int64(bytesToRead)makes the entry length negative.reader.go:350:ReadAllFileData'slength > maxSizecheck is a signed compare,so the negative length passes it.
reader.go:375:make([]byte, size)panics.These values are attacker-controlled in any TDF. The existing fuzz harness already
exercised this code; it just had no seed that reached the panic.
Four other paths had the same problem:
CDOffset, the central-directory cursor, and the local headeroffset were all converted unchecked.
ReadAllFileDatawould return ZIP metadata as file content.ReadFileDataboundedlengthbut notindex. A TDF reader computesindexby addingup the manifest's segment sizes, so a forged manifest could read past the end of the
entry.
The fix
Every position read from disk is now checked through a small unexported
boundtypebefore it reaches a
Seekormake:archiveBoundderives the archive length from the EOCDSeek, whichthe code already made but whose return value it discarded.
narrowuses that to checkthe central directory start read from the file.
length.
against its start.
int64, a single checkrejects values above
MaxInt64and values that are merely out of range. The subtractionkeeps the addition from wrapping before it is checked.
exactly at the central directory in every archive our writer emits.
TestWriterManifestEndsAtCentralDirectorypins this.uint64arguments in a row would still compileif two were swapped, silently breaking the check. Each
boundalso carries its own namefor error messages.
archive / cdFileHeaderSize, so animpossible count fails immediately instead of after billions of failed seeks.
ReadFileData. It now checksindexas well aslength. Its error names theentry, offset, length and entry size instead of a bare
zip: not a valid file size.This is the read-side counterpart to
checkFitsInCentralDirectoryfrom #3981, whichrefuses to write a value too large for a 32-bit field. Until now nothing checked a hostile
64-bit value on the way back in.
Why not
uint64internal/package, so nothing outside it needsuint64.io.ReadSeeker.Seek,make(), and theint64returned by
ReadFileData,ReadAllFileDataandReadFileSize, whichTDFReaderpasses on to
sdk/tdf.go.uint64storage would only move the conversion intoreadBytes, where there is noarchive length to check against.
make([]byte, hugeUint64)still panics.The type is renamed to
zipFileEntry(it was never used outside the package). It keepssigned fields, with a documented guarantee: both are non-negative and
index+lengthisat most the start of the central directory.
Testing
zip64_conformance_test.gotests each check separately. Several checks returnerrZipFormat, so each test also asserts which check fired, not justerrors.Is(err, errZipFormat).buildRawZipgained override fields so a fixture candeclare a false ZIP64 size or offset.
TestReaderRejectsZip64ValuesBeyondArchivecovers stored sizeand header offset, each above
MaxInt64and just past EOF.TestReaderEntryBoundaryIsCentralDirectoryaccepts data ending exactly at the centraldirectory and rejects one byte more.
TestReaderRejectsEntryOverrunningCentralDirectoryrejects a size that stays insidethe archive but extends past the central directory.
TestWriterManifestEndsAtCentralDirectorycovers archives our writer produces.TestReaderRejectsZip64LocatorOffsetBeyondArchiveTestReaderRejectsCentralDirectoryStartBeyondArchiveTestReaderRejectsCentralDirectoryWalkBeyondArchiveTestReaderBoundsLocalHeaderByCentralDirectoryTestReaderRejectsLocalHeaderLengthsOverrunningCentralDirectoryTestReaderRejectsEntryCountBeyondArchiveTestReaderRejectsImplausibleSeekPositionReadFileDataoffsets:TestReadFileDataBoundsIndex.FuzzReader:1<<63panic, and a size that extends past the central directory.directory, that in-range
ReadFileDatacalls succeed, and that{size, 1}fails.Temporarily removing the index check makes it fail on its first seed.
Each check was broken in turn to confirm that at least one test fails without it.
go test ./internal/zipstream/... -racepasses.make fuzzpasses for every target. A longerFuzzReaderrun reached over 40Mexecutions with no crashes.
golangci-lint run ./internal/zipstream/...reports 0 issues, andgofmtis clean.Not in this PR (problems that predate it)
errZipFormatFileHeaderdoesn't wraperrZipFormat, and several bareerrZipFormatreturns don't say which record was bad.
Summary by CodeRabbit
Bug Fixes
Tests