On Wed, Oct 13, 2021 at 09:16:37AM -0400, Stephen Frost wrote: > Greetings, > > * Ants Aasma (a...@cybertec.at) wrote: > > On Wed, 13 Oct 2021 at 02:20, Bruce Momjian <br...@momjian.us> wrote: > > > On Wed, Oct 13, 2021 at 12:48:51AM +0300, Ants Aasma wrote: > > > > On Wed, 13 Oct 2021 at 00:25, Bruce Momjian <br...@momjian.us> wrote: > > > > > > > > On Tue, Oct 12, 2021 at 11:21:28PM +0300, Ants Aasma wrote: > > > > > Page encrypting to all zeros is for all practical purposes > > > impossible to > > > > hit. > > > > > Basically an attacker would have to be able to arbitrarily set the > > > whole > > > > > contents of the page and they would then achieve that this page > > > gets > > > > ignored. > > > > > > > > Uh, how do we know that valid data can't produce an encrypted > > > all-zero > > > > page? > > > > > > > > > > > > Because the chances of that happening by accident are equivalent to > > > making a > > > > series of commits to postgres and ending up with the same git commit > > > hash 400 > > > > times in a row. > > > > > > Yes, 256^8192 is 1e+19728, but why not just assume a page LSN=0 is an > > > empty page, and if not, an error? Seems easier than checking if each > > > page contains all zeros every time. > > > > > > > We already check it anyway, see PageIsVerifiedExtended(). > > Right- we check the LSN along with the rest of the page there.
Very good. I have not looked at the Cybertec patch recently. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com If only the physical world exists, free will is an illusion.
