MySQL 5.7 introduced the class page_size_t and increased the size of
buffer pool page descriptors by introducing this object to them.
Maybe the intention of this exercise was to prepare for a future
where the buffer pool could accommodate multiple page sizes.
But that future never arrived, not even in MySQL 8.0. It is much
easier to manage a pool of a single page size, and typically all
storage devices of an InnoDB instance benefit from using the same
page size.
Let us remove page_size_t from MariaDB Server. This will make it
easier to remove support for ROW_FORMAT=COMPRESSED (or make it a
compile-time option) in the future, just by removing various
occurrences of zip_size.
Fix one more bug in "DDL redo" phase in prepare
If table was renamed, and then new table was created with the old name,
prepare can be confused, and .ibd can end up with wrong name.
Fix the order of how DDL fixup is applied , once again - ".new" files
should be processed after renames.
If, during backup
1) Innodb table is dropped (after being copied to backup) and then
2) Before backup finished, another Innodb table is renamed, and new name
is the name of the dropped table in 1)
then, --prepare fails with assertion, as DDL fixup code in prepare
did not handle this specific case.
The fix is to process drops before renames, in prepare DDL-"redo" phase.
If an encrypted table is created during backup, then
mariabackup --backup could wrongly fail.
This caused a failure of the test mariabackup.huge_lsn once on buildbot.
This is due to the way how InnoDB creates .ibd files. It would first
write a dummy page 0 with no encryption information. Due to this,
xb_fil_cur_open() could wrongly interpret that the table is not encrypted.
Subsequently, page_is_corrupted() would compare the computed page
checksum to the wrong checksum. (There are both "before" and "after"
checksums for encrypted pages.)
To work around this problem, we introduce a Boolean option
--backup-encrypted that is enabled by default. With this option,
Mariabackup will assume that a nonzero key_version implies that the
page is encrypted. We need this option in order to be able to copy
encrypted tables from MariaDB 10.1 or 10.2, because unencrypted pages
that were originally created before MySQL 5.1.48 could contain nonzero
garbage in the fields that were repurposed for encryption.
Later, MDEV-18128 would clean up the way how .ibd files are created,
to remove the need for this option.
page_is_corrupted(): Add missing const qualifiers, and do not check
space->crypt_data unless --skip-backup-encrypted has been specified.
xb_fil_cur_read(): After a failed page read, output a page dump.
would not hide more interesting information, like invalid memory accesses.
some "leaks" are expected
- partly this is due to weird options parsing, that runs twice, and
does not free memory after the first run.
- also we do not mind to exit() whenever it makes sense, without full
cleanup.
- Refactor code to isolate page validation in page_is_corrupted() function.
- Introduce --extended-validation parameter(default OFF) for mariabackup
--backup to enable decryption of encrypted uncompressed pages during
backup.
- mariabackup would still always check checksum on encrypted data,
it is needed to detect partially written pages.
Write a test case that computes valid crc32 checksums for
an encrypted page, but zeroes out the payload area, so
that the checksum after decryption fails.
xb_fil_cur_read(): Validate the page number before trying
any checksum calculation or decrypting or decompression.
Also, skip zero-filled pages. For page_compressed pages,
ensure that the FIL_PAGE_TYPE was changed. Also, reject
FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED if no decryption was attempted.
Problem:
=======
Mariabackup seems to fail to verify the pages of compressed tables.
The reason is that both fil_space_verify_crypt_checksum() and
buf_page_is_corrupted() will skip the validation for compressed pages.
Fix:
====
Mariabackup should call fil_page_decompress() for compressed and encrypted
compressed page. After that, call buf_page_is_corrupted() to
check the page corruption.
The initial fix only covered a part of Mariabackup.
This fix hardens InnoDB and XtraDB in a similar way, in order
to reduce the probability of mistaking a corrupted encrypted page
for a valid unencrypted one.
This is based on work by Thirunarayanan Balathandayuthapani.
fil_space_verify_crypt_checksum(): Assert that key_version!=0.
Let the callers guarantee that. Now that we have this assertion,
we also know that buf_page_is_zeroes() cannot hold.
Also, remove all diagnostic output and related parameters,
and let the relevant callers emit such messages.
Last but not least, validate the post-encryption checksum
according to the innodb_checksum_algorithm (only accepting
one checksum for the strict variants), and no longer
try to validate the page as if it was unencrypted.
buf_page_is_zeroes(): Move to the compilation unit of the only callers,
and declare static.
xb_fil_cur_read(), buf_page_check_corrupt(): Add a condition before
calling fil_space_verify_crypt_checksum(). This is a non-functional
change.
buf_dblwr_process(): Validate the page only as encrypted or unencrypted,
but not both.
