I have set up a chroot jail for user chroottest in /home/chroot
Steps to reproduce:
root@pc# mkdir /home/chroot
root@pc# mkdir /home/chroot/dev
root@pc# mkdir /home/chroot/etc
root@pc# mkdir /home/chroot/bin
root@pc# mkdir /home/chroot/usr
root@pc# mkdir /home/chroot/usr/bin
root@pc# mkdir /home/chroot/usr/lib
root@pc# mkdir /home/chroot/usr/lib/terminfo
root@pc# mkdir /home/chroot/lib
root@pc# mkdir /home/chroot/lib/x86_64-linux-gnu
root@pc# mkdir /home/chroot/lib64
root@pc#
root@pc# mknod -m 666 null c 1 3
root@pc# mknod -m 666 tty c 5 0
root@pc# mknod -m 666 zero c 1 5
root@pc# mknod -m 666 random c 1 8
root@pc#
root@pc# cp /bin/bash /home/chroot/bin
root@pc# cp /usr/bin/ls /home/chroot/usr/bin
root@pc# cp /usr/bin/getent /home/chroot/usr/bin
root@pc# cp -av /usr/lib/terminfo /home/chroot/usr/lib/terminfo
root@pc#
root@pc# cp /lib/x86_64-linux-gnu/libtinfo.so.6 /home/chroot/lib/x86_64-linux-gnu/
root@pc# cp /lib/x86_64-linux-gnu/libdl.so.2 /home/chroot/lib/x86_64-linux-gnu/
root@pc# cp /lib/x86_64-linux-gnu/libc.so.6 /home/chroot/lib/x86_64-linux-gnu/
root@pc# cp /lib/x86_64-linux-gnu/libpthread.so.0 /home/chroot/lib/x86_64-linux-gnu/
root@pc# cp /lib/x86_64-linux-gnu/libselinux.so.1 /home/chroot/lib/x86_64-linux-gnu/
root@pc# cp /lib/x86_64-linux-gnu/libpcre2-8.so.0 /home/chroot/lib/x86_64-linux-gnu/
root@pc# cp /lib64/ld-linux-x86-64.so.2 /home/chroot/lib64/
root@pc#
root@pc# useradd chroottest -s /bin/bash
root@pc# passwd chroottest
root@pc#
root@pc# cp /etc/passwd /home/chroot/etc/
root@pc# cp /etc/group /home/chroot/etc/
root@pc# cp /etc/nsswitch.conf /home/chroot/etc/
root@pc#
root@pc# echo -e "Match User chroottest\n\tChrootDirectory /home/chroot" >> /etc/ssh/sshd_config
root@pc# systemctl reload sshd
When I connect via ssh as the user chroottest, I get chrooted correctly, but expected output of "ls -lh" would be
chroottest@pc# ls -lh
total 24K
drwxr-xr-x 2 root root 4.0K Nov 8 20:36 bin
drwxr-xr-x 2 root root 4.0K Nov 8 20:35 dev
drwxr-xr-x 2 root root 4.0K Nov 8 20:41 etc
drwxr-xr-x 3 root root 4.0K Nov 8 20:37 lib
drwxr-xr-x 2 root root 4.0K Nov 8 20:38 lib64
drwxr-xr-x 5 root root 4.0K Nov 8 21:00 usr
But it is
drwxr-xr-x 2 0 0 4.0K Nov 5 13:52 bin
drwxr-xr-x 2 0 0 4.0K Oct 22 05:47 dev
drwxr-xr-x 2 0 0 4.0K Nov 5 14:02 etc
drwxr-xr-x 4 0 0 4.0K Nov 5 13:57 lib
drwxr-xr-x 2 0 0 4.0K Oct 22 05:51 lib64
drwxr-xr-x 3 0 0 4.0K Nov 5 13:54 usr
I only see IDs instead of usernames and groups. File system rights are impossible to manage that way…
The content of nsswitch.conf ist:
root@pc# cat /home/chroot/etc/nsswitch.conf
passwd: files systemd
group: files systemd
shadow: files
gshadow: files
hosts: files dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
getent seems to be unable to get any information in the chroot environment:
chroottest@pc# getent passwd
chroottest@pc# getent passwd chroottest
chroottest@pc#
Any idea on what could be the problem?
Thanks, Mike
Best Answer
Ferenc Wágner's and Totor's comments combined gave me the answer:
You have to copy /etc/nsswitch.conf and libnss.files.so.2 library to the chroot environment as well for the system to be able to interpret users and groups from passwd and group files.