Summary:
This applies some mitigations suggested by SQLite authors when
opening untrusted SQLite databases, as we do when Grist docs
are uploaded by the user. See:
https://www.sqlite.org/security.html#untrusted_sqlite_database_files
Steps implemented in this diff are:
* Setting `trusted_schema` to off
* Running a SQLite-level integrity check on uploads
Other steps will require updates to our node-sqlite3 fork, since they
are not available via the node-sqlite3 api (one more reason to migrate
to better-sqlite3).
I haven't yet managed to create a file that triggers an integrity
check failure without also being detected as corruption by sqlite
at a more basic level, so that is a TODO for testing.
Test Plan:
existing tests pass; need to come up with exploits to
actually test the defences and have not yet
Reviewers: dsagal
Reviewed By: dsagal
Differential Revision: https://phab.getgrist.com/D2909
