linux-kernel - Re: [PATCH v3 2/5] efi: stub: use random seed from EFI variable

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Message-ID: <20221127211244.GB32253@srcf.ucam.org>
Date:   Sun, 27 Nov 2022 21:12:44 +0000
From:   Matthew Garrett <mjg59@...f.ucam.org>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-efi@...r.kernel.org, linux-crypto@...r.kernel.org,
        patches@...ts.linux.dev, linux-kernel@...r.kernel.org,
        ardb@...nel.org
Subject: Re: [PATCH v3 2/5] efi: stub: use random seed from EFI variable

On Tue, Nov 22, 2022 at 03:04:01AM +0100, Jason A. Donenfeld wrote:

> +		 * We delete the seed here, and /hope/ that this causes EFI to
> +		 * also zero out its representation on disk. This is somewhat

Several implementations I've worked with simply append a deletion marker 
or append a new variable value until the variable store fills up 
entirely, at which point a garbage collection event is either run or 
scheduled for the next reboot. The spec doesn't define how this is 
handled so unfortunately I don't think there's any way to get a pony 
here.