From: Eric Biggers <ebiggers@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: axboe@kernel.dk, jaegeuk@kernel.org, chao@kernel.org,
ulf.hansson@linaro.org, Adrian Hunter <adrian.hunter@intel.com>,
Daeho Jeong <daehojeong@google.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mmc@vger.kernel.org
Subject: Re: security issue: data exposure when using block layer secure erase
Date: Wed, 16 Mar 2022 18:05:29 +0000 [thread overview]
Message-ID: <YjIm6f6pSX1CKeqb@gmail.com> (raw)
In-Reply-To: <20220316093740.GA7714@lst.de>
On Wed, Mar 16, 2022 at 10:37:40AM +0100, Christoph Hellwig wrote:
> Hi all,
>
> while staring at the block layer code I found what I think is a major
> security issue with the use of REQ_OP_SECURE_ERASE.
>
> The issue is not about the actual protocol implementation, which only
> exists for eMMC [1], but about we handle issuing the operation in the
> block layer. That is done through __blkdev_issue_discard, which
> takes various parameters into account to align the issue discard
> request to what the hardware prefers. Which is perfectly fine for
> discard as an advisory operation, but deadly for an operation that
> wants to make data inaccessible. The problem has existed ever since
> secure erase support was added to the kernel with commit
> 8d57a98ccd0b ("block: add secure discard"), which added secure erase
> support as a REQ_SECURE flag to the discard operation.
__blkdev_issue_discard() can break up the region into multiple bios, but I don't
see where it actually skips parts of the region. Can you explain more
specifically where the problem is?
- Eric
next prev parent reply other threads:[~2022-03-16 18:05 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-16 9:37 security issue: data exposure when using block layer secure erase Christoph Hellwig
2022-03-16 9:38 ` [PATCH, alternative 1] block: remove REQ_OP_SECURE_ERASE erase Christoph Hellwig
2022-03-16 9:38 ` [PATCH alternative 2] block: fix the REQ_OP_SECURE_ERASE handling to not leak erased data Christoph Hellwig
2022-03-17 9:44 ` Ulf Hansson
2022-03-18 9:11 ` Christoph Hellwig
2022-03-18 10:36 ` Ulf Hansson
2022-03-16 18:05 ` Eric Biggers [this message]
2022-03-17 9:57 ` security issue: data exposure when using block layer secure erase Joel Granados
2022-03-18 9:10 ` Christoph Hellwig
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