Problem with devmapper?

[nitpicker]

Hi everyone!

After a few successful projects with piCore 8 and 9, I'm now trying to set up a file server using piCore 9.0.3. In order to encrypt the personal files on the storage device, I usually rely on cryptsetup / LUKS.

Since I couldn't find an extension providing cryptsetup in the 9.x repo, I've compiled cryptsetup and created a new extension.
There wasn't a problem during compilation and cryptsetup starts without complaints after being "inserted" into the system using tce-load. But after entering the passphrase for formatting or creating an encrypted device, the program seems to get caught in an endless loop.

I've already tried different versions of cryptsetup (1.7.5 and 2.0.0, the latter needed an additional library for luks2: libargon2) and different versions of piCore (9.0.3 and 8.1.5), but each combination shows the same behavior.

I've also compiled cryptsetup with debug symbols and attached gdb to the running process to see where it gets stuck. The backtrace shows that it's locked somewhere in libdevmapper.
I've also been experiencing problems when using losetup to attach a loop device to a file:

Code: [Select]

dd if=/dev/zero of=test.img bs=1M count=128
chmod 666 test.img
sudo losetup -f test.imgjust tells me that it can't find that image file.

So now I'm wondering if there are any known issues with the device mapper in piCore? I suppose it should work flawlessly, because all the extensions are installed using loop devices...

Btw, I've tried to use cryptsetup on Raspbian (using the same setup: Pi + external harddisk) and that worked just fine. I've even created an extension for piCore containing Raspbian's cryptsetup binary along with the required libraries. This one also hung after entering the passphrase, so I really don't think it's a cryptsetup issue...

Any input on that issue would be greatly appreciated!

Best regards
Tim

[curaga]

Just noting that normal loops do not use devmapper.

[nitpicker]

Just noting that normal loops do not use devmapper.

Good to know. So, that was a wrong assumption of mine because neither cryptsetup nor losetup were able to create the required loop device... 

Today, I've tried to reach me goal by using veracrypt.
Veracrypt is able to create an encrypted container on the harddisk, but when it fires up dmsetup to create a container device to mount the volume, it's also in a deadlock.

I'm running out of ideas. 
Am I the only one having problems with dmsetup & friends, or am I making some stupid mistake?

[bmarkus]

There are two main differences in piCore compared to Raspbian. First, most kernel modules are not installed by default. You may need modules to install for encryption or other use. Is dm-...tcz installed? Check loaded modules on Raspbian. Second is buysbox. You may need the standard utilities, install coreutils.tcz

[nitpicker]

Thanks for the hints!

Second is buysbox. You may need the standard utilities, install coreutils.tcz

I had already been aware that losetup was provided by busybox, but I had expected it to work nonetheless. 
You're right, installing util-linux provides the "full" version, which works as it should. No more "file not found" errors.

You may need modules to install for encryption or other use

I've compared the output of lsmod on both Raspbian and piCore:

module	Raspbian	piCore	remarks
af_alg	yes	(yes)	crypto, compiled into piCore kernel
algif_skcipher	yes	(yes)	crypto, compiled into piCore kernel
bcm2835_gpiomem	yes	yes
bluetooth	yes		bluetooth stuff
bnep	yes		bluetooth stuff
brcmfmac	yes		wireless stuff
brcmutil	yes		wireless stuff
btbcm	yes		bluetooth stuff
cfg80211	yes		wireless stuff
cmac	yes		crypto
dm_crypt	yes		suspect!
dm_mod	yes		suspect!
drm	yes		direct rendering
drm_kms_helper	yes		direct rendering
evdev	yes	yes
fb_sys_fops	yes		frame buffer
fixed	yes	yes
gf128mul	yes	(yes)	crypto, compiled into piCore kernel
hci_uart	yes		bluetooth stuff
i2c_algo_bit	yes		i2c bus
i2c_bcm2835	yes		i2c bus
i2c_dev	yes	yes	i2c bus
i2c_gpio	yes		i2c bus
ip_tables	yes		network stuff
ipv6	yes		network stuff
panel_raspberrypi_touchscreen	yes		panel stuff
rfkill	yes	yes
sg	yes		SCSI driver
snd	yes		sound
snd_bcm2835	yes		sound
snd_compress	yes		sound
snd_pcm	yes		sound
snd_pcm_dmaengine	yes		sound
snd_timer	yes		sound
snd_soc_core	yes		sound
squashfs		yes
syscopyarea	yes		direct rendering
sysfillrect	yes		direct rendering
sysimgblt	yes		direct rendering
uio	yes	yes	userspace I/O
uio_pdrv_genirq	yes	yes	userspace I/O
vc4	yes		direct rendering
x_tables	yes		network stuff
xts	yes	(yes)	crypto, compiled into piCore kernel
zram		yes
zsmalloc		yes

The only suspects I could identify were dm_mod and dm_crypt. I modprobe'd both, but that didn't change anything.

Since lsmod only provides information about modules and doesn't show what's been compiled into the kernel, I also compared the default config of the Raspbian kernel and the piCore kernel. But I can't see anything suspicious there. I'm attaching the info that diff gave me to this post.

Is dm-...tcz installed?

Yes. I included lvm2 as a dependency for the cryptsetup extension, which requires raid-dm-KERNEL.tcz for itself.

[bmarkus]

Check the full kernel module archive on the server download are for missing modules. Less frequently used moduels are not packed into a .tcz you must do it yourself.