Hi Try to set up dm-verity with block size 512 bytes. I don't know what block size does squashfs use, but if the filesystem block size is smaller than dm-verity block size, it doesn't work. Mikulas On Tue, 20 Jul 2021, Pintu Agarwal wrote: > Hi, > > Our ARM32 Linux embedded system consists of these: > * Linux Kernel: 4.14 > * Processor: Qualcomm Arm32 Cortex-A7 > * Storage: NAND 512MB > * Platform: Simple busybox > * Filesystem: UBIFS, Squashfs > * Consists of nand raw partitions, squashfs ubi volumes. > > My requirement: > We wanted to use dm-verity at boot time to check the integrity of > squashfs-rootfs before mounting. > > Problem: > dm-0 is not able to locate and mount the squash fs rootfs block. > The same approach is working when emulating with ext4 but fails with squashfs. > > Logs: > [....] > [ 0.000000] Kernel command line: [...] verity="96160 12020 > d7b8a7d0c01b9aec888930841313a81603a50a2a7be44631c4c813197a50d681 0 " > rootfstype=squashfs root=/dev/mtdblock34 ubi.mtd=30,0,30 [...] > root=/dev/dm-0 dm="system none ro,0 96160 verity 1 /dev/mtdblock34 > /dev/mtdblock39 4096 4096 12020 8 sha256 > d7b8a7d0c01b9aec888930841313a81603a50a2a7be44631c4c813197a50d681 > aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7" > [....] > [ 4.693620] vreg_conn_pa: disa▒[ 4.700662] md: Skipping > autodetection of RAID arrays. (raid=autodetect will force) > [ 4.700713] device-mapper: init: attempting early device configuration. > [ 4.708224] device-mapper: init: adding target '0 96160 verity 1 > /dev/mtdblock34 /dev/mtdblock39 4096 4096 12020 8 sha256 > d7b8a7d0c01b9aec888930841313a81603a50a2a7be44631c4c813197a50d681 > aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7' > [ 4.714979] device-mapper: verity: sha256 using implementation > "sha256-generic" > [ 4.737808] device-mapper: init: dm-0 is ready > [....] > [ 5.278103] No filesystem could mount root, tried: > [ 5.278107] squashfs > [ 5.280477] > [ 5.287627] Kernel panic - not syncing: VFS: Unable to mount root > fs on unknown-block(253,0) > [...] > > Not sure, why is it still locating block "253" here which seems like a > MAJOR number ? > > Working logs on ext4: > [....] > [ 4.529822] v▒[ 4.534035] md: Skipping autodetection of RAID > arrays. (raid=autodetect will force) > [ 4.534087] device-mapper: init: attempting early device configuration. > [ 4.550316] device-mapper: init: adding target '0 384440 verity 1 > /dev/ubiblock0_0 /dev/ubiblock0_0 4096 4096 48055 48063 sha256 > a02e0c13afb31e99b999c64aae6f4644c24addbc58db5689902cc5ba0be2d15b > aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7 10 > restart_on_corruption ignore_zero_blocks use_fec_from_device > /dev/ubiblock0_0 fec_roots 2 fec_blocks 48443 fec_start 48443' > [ 4.572215] device-mapper: verity: sha256 using implementation > "sha256-generic" > [ 4.610692] device-mapper: init: dm-0 is ready > [ 4.720174] EXT4-fs (dm-0): mounted filesystem with ordered data > mode. Opts: (null) > [ 4.720438] VFS: Mounted root (ext4 filesystem) readonly on device 253:0. > [ 4.737256] devtmpfs: mounted > [....] > > Questions: > a) Is dm-verity supposed to work on squashfs block devices ? > b) Are there any known issues with dm-verity on Kernel 4.14 ? > c) Are there any patches that we are missing ? > > > Thanks, > Pintu >
