first commit

Dockerfile

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+FROM ubuntu:bionic AS build
+COPY uml.config /uml.config
+ENV LINUX_VERSION linux-4.19.57
+ENV LINUX_DOWNLOAD_URL https://cdn.kernel.org/pub/linux/kernel/v4.x/${LINUX_VERSION}.tar.xz
+RUN apt-get update \
+ && apt-get -y install build-essential flex bison xz-utils wget ca-certificates bc linux-headers-4.15.0-47-generic \
+ && wget ${LINUX_DOWNLOAD_URL} \
+ && tar xJf ${LINUX_VERSION}.tar.xz \
+ && rm ${LINUX_VERSION}.tar.xz \
+ && cd ${LINUX_VERSION} \
+ && cp /uml.config .config \
+ && make ARCH=um -j10 \
+ && mv ./linux / \
+ && cd .. \
+ && rm -rf ${LINUX_VERSION}
+
+FROM xena/alpine
+
+COPY --from=build /linux /linux
+ADD https://xena.greedo.xeserv.us/files/slirp /slirp
+
+# Add Tini
+ENV TINI_VERSION v0.18.0
+ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini-static /chroot/tini
+RUN chmod +x /chroot/tini
+
+# Set up chroot
+RUN cd /chroot \
+ && wget -O - http://dl-cdn.alpinelinux.org/alpine/v3.10/releases/x86_64/alpine-minirootfs-3.10.0-x86_64.tar.gz | tar xz \
+ && chmod +x /linux \
+ && chmod +x /slirp
+COPY init.sh /chroot/init.sh
+COPY resolv.conf /chroot/etc/resolv.conf
+
+COPY runlinux.sh /runlinux.sh
+CMD /runlinux.sh

LICENSE

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+Copyright (c) 2019 Christine Dodrill <me@christine.website>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# furry-happiness
+
+A proof of concept [user mode linux](https://en.wikipedia.org/wiki/User-mode_Linux)
+Docker image. This builds a simply configured kernel and sets up an [Alpine Linux](https://alpinelinux.org)
+userland for it. It has fully working networking via slirp.
+
+This runs an entire Linux kernel as a userspace process inside a docker container.
+Anything you can do as root in a linux kernel, you can do inside this user mode
+Linux process. The root inside this user mode Linux kernel has significanly more
+power than root outside of the kernel, but it cannot affect the host kernel.
+
+To build:
+
+```
+docker build -t xena/docker-uml .
+```
+
+To run:
+
+```
+docker run --rm -it xena/docker-uml
+```

init.sh

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+#!/bin/sh
+
+mount -t proc proc proc/
+mount -t sysfs sys sys/
+ifconfig eth0 10.0.2.14 netmask 255.255.255.240 broadcast 10.0.2.15
+route add default gw 10.0.2.2
+
+reset
+uname -av
+echo "networking set up"
+
+exec /tini /bin/sh

resolv.conf

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+nameserver 1.1.1.1
+nameserver 8.8.8.8

runlinux.sh

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+#!/bin/sh
+
+export TMP=/chroot
+exec /chroot/tini /linux root=/dev/root rootflags=/chroot rootfstype=hostfs rw mem=128M udb0=alpine-root verbose eth0=slirp,,/slirp init=/init.sh