another approach

Dockerfile

@@ -3,7 +3,6 @@ LABEL maintainer="Rapid7"
 
 ARG BUNDLER_ARGS="--jobs=8 --without development test coverage"
 ENV APP_HOME /usr/src/metasploit-framework/
-ENV MSF_USER msf
 ENV NMAP_PRIVILEGED=""
 ENV BUNDLE_IGNORE_MESSAGES="true"
 WORKDIR $APP_HOME
@@ -15,6 +14,7 @@ COPY lib/msf/util/helper.rb $APP_HOME/lib/msf/util/helper.rb
 
 RUN apk update && \
     apk add \
+      bash \
       sqlite-libs \
       nmap \
       nmap-scripts \
@@ -24,6 +24,7 @@ RUN apk update && \
       python3 \
       ncurses \
       libcap \
+      su-exec \
     && apk add --virtual .ruby-builddeps \
       autoconf \
       bison \
@@ -47,13 +48,16 @@ RUN apk update && \
     && apk del .ruby-builddeps \
     && rm -rf /var/cache/apk/*
 
-RUN adduser -g msfconsole -D $MSF_USER -u 1000
-
 RUN /usr/sbin/setcap cap_net_raw,cap_net_bind_service=+eip $(which ruby)
 RUN /usr/sbin/setcap cap_net_raw,cap_net_bind_service=+eip $(which nmap)
 
-USER $MSF_USER
-
 ADD ./ $APP_HOME
 
+# we need this entrypoint to dynamically create a user
+# matching the hosts UID and GID so we can mount something
+# from the users home directory. If the IDs don't match
+# it results in access denied errors. Once docker has
+# a solution for this we can revert it back to normal
+ENTRYPOINT ["docker/entrypoint.sh"]
+
 CMD ["./msfconsole", "-r", "docker/msfconsole.rc"]

docker/README.md

@@ -3,24 +3,27 @@
 
 To run `msfconsole`
 ```bash
-docker-compose build
-docker-compose run --rm --service-ports ms
-```
-or
-```bash
 ./docker/bin/msfconsole
 ```
 
-To run `msfvenom`
+or
+
 ```bash
 docker-compose build
-docker-compose run --rm --no-deps ms ./msfvenom
+docker-compose run --rm --service-ports -e MSF_UID=$(id -u) -e MSF_GID=$(id -g) ms
 ```
-or
+To run `msfvenom`
 ```bash
 ./docker/bin/msfvenom
 ```
 
+or
+
+```bash
+docker-compose build
+docker-compose run --rm --no-deps -e MSF_UID=$(id -u) -e MSF_GID=$(id -g) ms ./msfvenom
+```
+
 You can pass any command line arguments to the binstubs or the docker-compose command and they will be passed to `msfconsole` or `msfvenom`. If you need to rebuild an image (for example when the Gemfile changes) you need to build the docker image using `docker-compose build` or supply the `--rebuild` parameter to the binstubs.
 
 ### But I want reverse shells...

docker/bin/msfconsole

@@ -27,10 +27,4 @@ if [[ $PARAMS == *"--rebuild"* ]]; then
   exit $?
 fi
 
-# workaround if current user id is not the same as in the container.
-# Otherwise the ~/.msf4 folder is not writeable
-if [[ $EUID -ne 1000 ]]; then
-  docker-compose run --rm -u root --service-ports ms ./msfconsole -r docker/msfconsole.rc "$PARAMS"
-else
-  docker-compose run --rm --service-ports ms ./msfconsole -r docker/msfconsole.rc "$PARAMS"
-fi
+docker-compose run --rm --service-ports -e MSF_UID=$(id -u) -e MSF_GID=$(id -g) ms ./msfconsole -r docker/msfconsole.rc "$PARAMS"

docker/entrypoint.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+MSF_USER=msf
+MSF_GROUP=msf
+TMP=${MSF_UID:=1000}
+TMP=${MSF_GID:=1000}
+
+# don't recreate system users like root
+if [ "$MSF_UID" -lt "1000" ]; then
+  MSF_UID=1000
+fi
+
+if [ "$MSF_GID" -lt "1000" ]; then
+  MSF_GID=1000
+fi
+
+addgroup -g $MSF_GID $MSF_GROUP
+adduser -u $MSF_UID -D $MSF_USER -g $MSF_USER -G $MSF_GROUP $MSF_USER
+
+su-exec $MSF_USER "$@"