Extend Root Partition Failure (Kali + RPi 3b+)

Question

I have recently built a Raspberry Pi 3b+ with Kali Linux for the Pi (https://images.offensive-security.com/arm-images/kali-linux-2018.2-rpi3-nexmon.img.xz).

I have unpacked and dd the image onto my 32GB SanDisk microSD card. It has been configured for headless operation to connect to it with my cellphone for C&C through following this guide: https://null-byte.wonderhowto.com/how-to/set-up-headless-raspberry-pi-hacking-platform-running-kali-linux-0176182/

I can login to the Pi just fine, but as I started loading tools onto it through apt-get and Kali repositories, during the install of Metasploit (and dependencies) it error saying there was not enough space. Considering I access this through my phone, I am having to type the output I am seeing, so the format may be off, but the information is proper to the best of my ability. All commands are run as root.

First I did a df -h which shows:

Filesystem       Size    Used   Avail  Use%   Mounted On
/dev/root        6.7G    6.3G    31M   100%   /
devtmpfs         460M       0   460M     0%   /dev
tmpfs            464M       0   464M     0%   /dev/shm
tmpfs            464M     13M   452M     3%   /run
tmpfs            5.0M       0   5.0M     0%   /run/lock
tmpfs            464M       0   464M     0%   /sys/fs/cgroup
/dev/mmcblk0p1    61M     22M    40M    36%   /boot
tmpfs             93M     12K    93M     1%   /run/user/0
tmpfs             93M    4.0K    93M     1%   /run/user/109

I also did a lsblk output:

NAME          MAJ:MIN    RM    SIZE  RO   TYPE MOUNT
mmcblk0       179:0       0   29.7G   0   disk
|-mmcblk0p1   179:1       0     61M   0   part /boot
|-mmcblk0p2   179:2       0   29.7G   0   part /

I also tried a manual resize of the partitions, fdisk -l reports:

Device          Boot    Start         End   Sectors   Size  Id  Type
/dev/mmcblk0p1              1      125000    125000    61M   c  W95 FAT32 (LBA)
/dev/mmcblk0p2         125001    62333951  62208951  29.7G  83  Linux

As suggested, I also tried resize2fs /dev/mmcblk0p2:

Filesystem at /dev/mmcblk0p2 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 4
resize2fs: Permission denied to resize filesystem

I tried also installing both a 2015 and a 2016 copy of raspi-config to use the expand file system part.

As you can see, the /dev/mmcblk0p2 does register as 32GB and mounted to / but the /dev/root which is also mounted to / only shows 6.7GB in size (which was the default after flashing Kali originally). I work in cyber but I do not do pen testing, nor am I a net/sys admin, so I am out of my element here. I just don't know what else I can do to fix this problem. I don't understand why / shows as 32GB in one place but only 7GB in another.

I don't mind wiping the card and starting over, but I would like to avoid it if possible. I also understand that the card may be physically damaged, had too many writes, or be partially "ghostlocked" as suggested by some forum posts. I would like to try a few more things before I accept the card as bad and having to replace it.

Answer 1

Probably because you adjusted partition table with fdisk, but did not resize the partition with resize2fs

See Expanding partition on SD

Try running sudo resize2fs /dev/mmcblk0p2

NOTE This is what raspi-config does - it also sets the OS to run resize2fs on reboot.

Answer 2

I was able to fix the issue by plugging the card into another Kali machine and doing:

umount /dev/sdf2
fsck.ext4 /dev/sdf2

The /dev/sdf2 may differ on other machines, but I had to answer a few questions with a (all) and y (yes) for the fsck.ext4 check. It output a lot of fixed error messages and then a warning that the file system was modified. I removed the card from the desktop machine and put it back into the Pi, after boot I was able to do df -h to verify that / was 30GB in size as intended.

I am giving the points to @Milliways due to him suggesting me mount in another Linux machine, as I had not considered that it would matter, and that fsck would fix the error.