dm: add integrity target
The dm-integrity target emulates a block device that has additional per-sector tags that can be used for storing integrity information. A general problem with storing integrity tags with every sector is that writing the sector and the integrity tag must be atomic - i.e. in case of crash, either both sector and integrity tag or none of them is written. To guarantee write atomicity the dm-integrity target uses a journal. It writes sector data and integrity tags into a journal, commits the journal and then copies the data and integrity tags to their respective location. The dm-integrity target can be used with the dm-crypt target - in this situation the dm-crypt target creates the integrity data and passes them to the dm-integrity target via bio_integrity_payload attached to the bio. In this mode, the dm-crypt and dm-integrity targets provide authenticated disk encryption - if the attacker modifies the encrypted device, an I/O error is returned instead of random data. The dm-integrity target can also be used as a standalone target, in this mode it calculates and verifies the integrity tag internally. In this mode, the dm-integrity target can be used to detect silent data corruption on the disk or in the I/O path. Signed-off-by:Mikulas Patocka <mpatocka@redhat.com> Signed-off-by:
Milan Broz <gmazyland@gmail.com> Signed-off-by:
Mike Snitzer <snitzer@redhat.com>
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drivers/md/dm-integrity.c
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