CompleteMultipartUpload compared the per-part checksum taken from the
request body against the stored part checksum unconditionally, so a
client that sent only PartNumber and ETag for each part failed with
InvalidPart.
AWS S3 requires part level checksums in the completion body only for
composite checksum types. For full object types the client sends the
object level checksum in the request headers instead and does not retain
per-part values - that is the point of FULL_OBJECT. Reproduced with
boto3 1.43.58: it puts x-amz-checksum-crc32 on each UploadPart and the
full object checksum on the completion headers, but emits only ETag and
PartNumber in the completion body. A caller could only get such an upload
through by collecting the per-part checksums from the UploadPart
responses and echoing them back, which is exactly the bookkeeping
FULL_OBJECT exists to avoid and which no off-the-shelf SDK call does.
minio-go does echo them, which is why mc never hit this.
Treat the part checksum as optional when the upload declared a full
object checksum type and the client sent no part checksum at all. A part
carrying any checksum is still validated against the stored one -
including one sent under the wrong algorithm, which cannot match and is
rejected - composite uploads keep requiring a checksum for every part,
and the merged object checksum is still computed from the server stored,
upload time validated part checksums, never from client supplied values,
so integrity is unchanged.
Covered by API level tests over CRC32, CRC32C and CRC64NVME on both the
single drive and erasure backends, with guards for a wrong object
checksum, a wrong part checksum, a part checksum under another algorithm,
a mix of present and omitted part checksums, an absent object checksum,
and composite uploads still requiring every part checksum.
Fixes#31
Reported-by: Christophe Bornet <cbornet@users.noreply.github.com>
Co-authored-by: ChatGPT <noreply@openai.com>
Co-authored-by: Claude <noreply@anthropic.com>
Feng Ruohang