MrChrootBSD

This program is a chroot like utility for FreeBSD,which is by far the most sexy BSD available. I like PRoot for testing software(on linux) but I am anaware of such a tool for FreeBSD,so I was left in the dust. Meet MrChrootBSD,a non-root version of chroot sort of.

NOTICE

This software is going under major refactors including perimision emulation. Expect something juicy next week. Dont use it for anything serious now(or at all).

Features

Here is a list

• Do chroot in userspace
• Partial ptrace emulation(limited,you can run gdb in your MrChroot's sort of and it will make you happy maybe)
• (Currently) buggy user permisions database(perms.db using db(3))
• X11 within MrChrootBSD easily with the -X option.

Non-Features

Some of these will be removed(added to features) in the future

• Full ptrace emulation(Dont rely on PT_TO_SCE/PT_TO_SCX to work).
• jails
• daemons

Usage

This is early in development so stay tuned,use it like a normal chroot. Feel free to probe around the source code and send patches to my github.

git clone https://github.com/nrootconauto/MrChrootBSD.git
cd MrChrootBSD
wget https://download.freebsd.org/releases/amd64/14.1-RELEASE/base.txz
wget https://download.freebsd.org/releases/amd64/14.1-RELEASE/lib32.txz #Needed for gdb for some reason
mkdir chroot
cd ..
cmake .
make
cp /etc/resolv.conf chroot/etc # networking
./mchroot -t base.txz chroot # Accounts for perms.db database
./mchroot -t lib32.txz chroot # Accounts for perms.db database
./mchroot chroot /bin/sh
# pkg etc

X11 within MrChrootBSD

Use -X option to allow /var/run and XAUTHORITY to be set so you can run X11 apps.

Things to do after chroot'ing

Copy /etc/resolv.conf into /etc.

You'll want to do this for networking

passwd root and install daos

su wont work for now(if ever). doas works like a charm when configured correctly.

pkg install doas
echo 'permit nopass :wheel' > /usr/local/etc/doas.conf
adduser -Z

MAKE SURE TO USE -Z with adduser TO NOT MAKE A ZFS dataset.

How it works internally

It uses ptrace to intercept the calls and reroute the file names to the host filesystem. Certian caeveats such as FreeBSD using the host filesystem for execvpe or telling the full path of the executable via elf_aux_info are patched in a LD_PRELOAD library called libpl_hack.so in preload_hack.c.

Development Please ;)

I could use help in these areas,I will probably get them done myself but if you want to make my day:

1. Add support for riscv64 and arm64 in abi.c.
2. Make the tool extremely fun to use(have emojis and stuff)
3. Implement procctl(3) reapers.
4. Make sure wait(2) actually works(probably does)
5. Validate existing sysctl(3) stuff(Probably works).
6. MAKE A ROBUST WAY TO TEST OF A PATH IS CHROOTED/UNCHROOTED(like make the paths start with '\01' or '\02')