Re: Kernel 4.14: Using dm-verity with squashfs rootfs - mounting issue

On Mon, 30 Aug 2021 at 22:25, Thomas Petazzoni
[off-list ref] wrote:

Hello,

On Mon, 30 Aug 2021 21:55:19 +0530
Pintu Agarwal [off-list ref] wrote:

quoted

Sorry for coming back to this again..
Unfortunately, none of the options is working for us with squashfs
(bootloader, initramfs).
initramfs have different kinds of challenges because of the partition
size issue.
So, our preferred option is still the bootloader command line approach..

Is there a proven and working solution of dm-verity with squashfs ?
If yes, please share some references.

The current problem with squashfs is that we could not append the
verity-metadata to squashfs, so we store it on a separate volume and
access it.

Here, it definitely worked to append the hash tree to the squashfs
image and store them in the same partition.

quoted

By specifying it like : /dev/mtdblock53

Then we get the error like this:
{
[    4.950276] device-mapper: init: attempting early device configuration.
[    4.957577] device-mapper: init: adding target '0 95384 verity 1
/dev/ubiblock0_0 /dev/mtdblock53 4096 4096 11923 8 sha256
16da5e4bbc706e5d90511d2a3dae373b5d878f9aebd522cd614a4faaace6baa3
aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7 10
restart_on_corruption ignore_zero_blocks use_fec_from_device
/dev/mtdblock53 fec_roots 2 fec_blocks 12026 fec_start 12026'
[    4.975283] device-mapper: verity: sha256 using implementation
"sha256-generic"
[    4.998728] device-mapper: init: dm-0 is ready

Could you show the full kernel command line ?

Shared below

quoted

Do you see any other problem here with dm-verity cmdline or with squashfs ?

Is squashfs ever proved to be working with dm-verity on higher kernel version ?
Currently our kernel version is 4.14.

I confirm we used squashfs on dm-verity successfully. For sure on 4.19,
perhaps on older kernels as well.

ohh that means we already have a working reference.
If possible can you share the details, even 4.19 or higher will be
also a good reference.

quoted

Or, another option is to use the new concept from 5.1 kernel that is:
dm-mod.create = ?

How are you doing it today without dm-mod.create ?

I think in 4.14 we don't have dm-mod.create right ?

Again, please give your complete kernel command line.

Here is our kernel command line:

[    0.000000] Kernel command line: ro rootwait
console=ttyMSM0,115200,n8 ....  verity="95384 11923
16da5e4bbc706e5d90511d2a3dae373b5d878f9aebd522cd614a4faaace6baa3 12026
" rootfstype=squashfs ubi.mtd=40,0,30 ubi.block=0,0 root=/dev/dm-0
.... init=/sbin/init root=/dev/dm-0 dm="rootfs none ro,0 95384 verity
1 /dev/ubiblock0_0 /dev/mtdblock53 4096 4096 11923 8 sha256
16da5e4bbc706e5d90511d2a3dae373b5d878f9aebd522cd614a4faaace6baa3
aee087a5be3b982978c923f566a94613496b417f2af592639bc80d141e34dfe7 10
restart_on_corruption ignore_zero_blocks use_fec_from_device
/dev/mtdblock53 fec_roots 2 fec_blocks 12026 fec_start 12026" ...

Do you see any issue here ?
Can you share your command line for squashfs to compare ?

Thank you,
Pintu

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