about

chrootkit is a simple chroot builder and bundler. You can easly create your chroot environment for the specified command set.

The command chrootkit has two aliases: addlib and podify.

addlib is a simple library bundler for commands. If you supplied commands as arguments, addlib copies these command binaries from your PATH and the libraries which these commands are dependent on. The last argument is parsed as a destination chroot directory. commands can be specified with command name or full path to the executable.

$ addlib bc some_chrootdir
mkdir: created directory 'some_chrootdir'
mkdir: created directory 'some_chrootdir//lib'
mkdir: created directory 'some_chrootdir//lib/x86_64-linux-gnu'
'/lib/x86_64-linux-gnu/libreadline.so.7' -> 'some_chrootdir//lib/x86_64-linux-gnu/libreadline.so.7'
'/lib/x86_64-linux-gnu/libncurses.so.6' -> 'some_chrootdir//lib/x86_64-linux-gnu/libncurses.so.6'
'/lib/x86_64-linux-gnu/libtinfo.so.6' -> 'some_chrootdir//lib/x86_64-linux-gnu/libtinfo.so.6'
'/lib/x86_64-linux-gnu/libc.so.6' -> 'some_chrootdir//lib/x86_64-linux-gnu/libc.so.6'
'/lib/x86_64-linux-gnu/libdl.so.2' -> 'some_chrootdir//lib/x86_64-linux-gnu/libdl.so.2'
mkdir: created directory 'some_chrootdir//lib64'
'/lib64/ld-linux-x86-64.so.2' -> 'some_chrootdir//lib64/ld-linux-x86-64.so.2'
'/lib/x86_64-linux-gnu/libreadline.so.7' -> 'some_chrootdir//lib/x86_64-linux-gnu/libreadline.so.7'
'/lib/x86_64-linux-gnu/libncurses.so.6' -> 'some_chrootdir//lib/x86_64-linux-gnu/libncurses.so.6'
'/lib/x86_64-linux-gnu/libtinfo.so.6' -> 'some_chrootdir//lib/x86_64-linux-gnu/libtinfo.so.6'
'/lib/x86_64-linux-gnu/libc.so.6' -> 'some_chrootdir//lib/x86_64-linux-gnu/libc.so.6'
'/lib/x86_64-linux-gnu/libdl.so.2' -> 'some_chrootdir//lib/x86_64-linux-gnu/libdl.so.2'
'/lib64/ld-linux-x86-64.so.2' -> 'some_chrootdir//lib64/ld-linux-x86-64.so.2'
mkdir: created directory 'some_chrootdir//usr'
mkdir: created directory 'some_chrootdir//usr/bin'
'/usr/bin/bc' -> 'some_chrootdir//usr/bin/bc'
'/usr/bin/bc' -> 'some_chrootdir//usr/bin/bc'

If you already have any contents inside some_chrootdir, they may be replaced with new libraries or executables (destructive action). Be sure to use new environment.

You can compose the chroot into a docker image, using podify command.

$ podify some_chrootdir mybc
Sending build context to Docker daemon  23.36MB
Step 1/3 : FROM scratch
 ---> 
Step 2/3 : ADD . /
 ---> b7bafda59918
Step 3/3 : CMD ["/bin/sh"]
 ---> Running in bfff6a8d64aa
 ---> 1b5ad4d24c88
Successfully built 1b5ad4d24c88
Successfully tagged mybc:latest

and run the container:

$ echo 2^16-1 | docker run -i -u 1500 bc /usr/bin/bc
65535

Requirement

• a shell with posix compliant behaivior (busybox, bash, dash, etc.)
• docker (if you need to pack them inside a docker image)
• POSIX compliant readlinkf as a command (recommended)

Usage

chrootkit [--add-libs|--bundle=docker]

addlib <executable,...> <destination>

podify <root> [name]

Author

okadas[at]tanban.org