Thanks for the input! See below On Fri, Feb 23, 2018 at 10:53 AM Gilad Ben-Yossef wrote: > On Fri, Feb 23, 2018 at 10:30 AM, Gigi W wrote: > > Hi > > > > I'm having some trouble using dm-verity for a squashfs root file system > that > > seems to be related to the > > Atmel SHA hw accelerator in the kernel, CONFIG_CRYPTO_DEV_ATMEL_SHA > > > > Some info about my setup: > > * I'm using a board with a SAMA5D4 CPU. > > * I'm using Yocto rocko for building an image for that device. > > > > The idea is that Using the 4.14.14 Kernel, Integrity checking using > Kernel > > crypto fails with Atmel SHA hw accelerator enabled in kernel. > > By disabling it, `CONFIG_CRYPTO_DEV_ATMEL_SHA=n`, and using the software > > sha256 algo, integrity checking works as expected. > > This is my kernel config [3] > > > > Using the 4.8.4 Kernel and Atmel SHA hw accelerator enabled, everything > was > > ok. > > > > This is what triggers the error during verified boot: > > > > status=`veritysetup create vroot $root_dev $verity_dev --hash-offset > > $hashoffset $root_hash` > > > > mount /dev/mapper/vroot /mnt/ > > mount_ok=`cat /proc/mounts | grep mnt` > > if [ -z "$mount_ok" ] ; then > > echo "Failed to mount $root_dev on mnt/" > > else > > echo "Switch rootfs" > > exec switch_root -c /dev/console /mnt /sbin/init > > fi > > > > The mount operation fails: > > > > device-mapper: verity: 179:4: metadata block 2 is corrupted > > EXT4-fs (dm-0): unable to read superblock > > device-mapper: verity: 179:4: metadata block 2 is corrupted > > EXT4-fs (dm-0): unable to read superblock > > device-mapper: verity: 179:4: metadata block 2 is corrupted > > EXT4-fs (dm-0): unable to read superblock > > device-mapper: verity: 179:4: metadata block 2 is corrupted > > SQUASHFS error: squashfs_read_data failed to read block 0x0 > > squashfs: SQUASHFS error: unable to read squashfs_super_block > > device-mapper: verity: 179:4: metadata block 2 is corrupted > > FAT-fs (dm-0): unable to read boot sector > > mount: mounting /dev/mapper/vroot on /mnt/ failed: Input/output error > > Failed to mount /dev/mmcblk0p4 on mnt/ > > reboot: Restarting system > > Reboot failed -- System halted > > > > Using veritysetup to verify the integrity against the hashes is > successful, > > as it's not using the kernel for that ... > > > > > > So it looks like it something changed from 4.8.4 to 4.14.14. > > If I am not mistaken the Atmel SHA hw accelerator is an async (read: > off CPU) crypto accelerator. > Up until 4.12 (I think...) DM-Verity did not use async crypto > accelerators (even if present and have high > priority). I've changed this is commit d1ac3ff008fb ("dm verity: > switch to using asynchronous hash crypto API"). > This would explain some things, like the same speeds while reading from a verity device, having the *CONFIG_CRYPTO_DEV_ATMEL_SHA* enabled and then disabled, on the 4.8.4 kernel -> it was always using the sync API. > > Is it possible that whatever issue you are seeing has always been > there and when DM-Verity started using > async. accelerators it was only exposed? > It looks like it. From my understandings + tests described above, Atmel SHA hw accelerator works correctly - output hashes are ok, dm-verity with other async crypto accelerators is working ok, but dm-verity + Atmel SHA hw accelerator don't play nice together. I couldn't find anyone else complaining about this. Best regards. > > > Using the 4.14.14 kernel, I removed the patches that were applied on the > > atmel-sha.c file in the kernel, one by one, until I got the version from > the > > 4.8.4 > > Basically I reverted the changes from > > here:https://git.kernel.org/pub/scm/linux/kernel/git/ > stable/linux-stable.git/log/drivers/crypto/atmel-sha.c?h=v4.14.14 > > until I got this: > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/ > linux-stable.git/log/drivers/crypto/atmel-sha.c?h=v4.8.4 > > > > It still didn't work. I assumed something there broke the hashing, not > the > > case. It was still not working with all those commits reverted. > > > > Furthermore, using the Cryptodev-linux module [1], and the sample [2], > > adapted to use sha256, I tested the output hashes, with > > CONFIG_CRYPTO_DEV_ATMEL_SHA enabled and then disabled. > > > > I got the same results in both cases, hardware and software algorithm. > So it > > doesn't look like the SHA hw accelerator is broken. > > > > > > Any help is appreciated ! > > > > Thanks in advanced and have a nice day. > > > > > > [1] http://cryptodev-linux.org/documentation.html > > [2] https://github.com/nmav/cryptodev-linux/blob/master/examples/sha.c > > [3] > > https://gist.githubusercontent.com/gmircea/ > 6e1cc029ef5ed7a16b0fedb8b9524f66/raw/eece8a8faadd2de9373e150ef1daf3 > cf25f4135c/.config > > > > > > -- > > dm-devel mailing list > > dm-devel@redhat.com > > https://www.redhat.com/mailman/listinfo/dm-devel > > > > -- > Gilad Ben-Yossef > Chief Coffee Drinker > > "If you take a class in large-scale robotics, can you end up in a > situation where the homework eats your dog?" > -- Jean-Baptiste Queru >