Explaining about the Docker Privileged

Explaining about the Docker Privileged
Techiio-author
Written by Nilima PaulFebruary 17, 2022
10 min read
Docker
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Techiio-author
Nilima Paul

Technology Security Analyst

We will know in this article, what's Docker Privileged.

Introduction to Docker Privileged:

The Docker special is a choice of the 'docker run' order in Docker. It permits our Docker holders to get to all gadgets (that is under the/dev organizer) appended to the host as a compartment isn't permitted to get to any gadgets because of safety reasons. A compartment acquires all abilities and can admittance to every one of the host's gadgets, for instance, CD-ROM, streak drives, hard drives joined to the host, even admittance to webcams while running in advantaged mode, in any case, we can restrict the entrance utilizing other various choices accessible in the 'docker run' order. This element is included Docker 0.6

How Privileged Function Works in Docker:

As we realize that the favored mode permits admittance to admittance to all gadgets associated with the host as like the host utilizing those gadgets or assets. It permits admittance to all associated gadgets as well as makes some arrangement changes in AppArmor or SELinux that permits the holder to have practically a similar admittance to the host as a cycle running external compartments on the host.

Examples:

Let’s understand the working process of the privileged mode with the below examples:

Scenario 1:

How about we run a non-special holder and an advantaged compartment and attempt to mount a circle inside the holder to store the information. Along these lines, how about we expect we have two circles joined to our host and we need to mount the second plate to the holder to store the information produced by the application running inside a compartment.

1. Non-Privileged Container:

Step 1: Run a container without the privileged option using the command shown below: –

docker run -it --rm <Docker_Image> sh
docker run -it --rm ubuntu sh

In the above preview, we can see that a holder has been begun utilizing the 'ubuntu' Docker picture and associated with the compartment. We have additionally utilized the '- rm' choice that will eliminate the holder once we exit. Great for the end goal of testing.

Step 2: Now, try to list the available disks using the ‘disk’ utility as shown below: –

fdisk -l

In the above depiction, we can see that it isn't showing any plates because the holder isn't running in the advantaged mode so it isn't showing the circle joined to it. How about we run another holder in favored mode.

2. Privileged Container:

Step 1: Run the below command to start a container in privileged mode, just have to use one extra flag that is the ‘–privilege’ option as shown below: –

docker run -it --rm --privileged <Docker_Image> sh
docker run -it --rm --privileged ubuntu sh

Step 2:Let’s run the ‘fdisk’ command to list available disks as shown below: –

fdisk –l

In the above preview, we can see that it has recorded all suitable plates data now and its parcels. Here, we will focus on '/dev/dba, the parcel has been as of now for this circle, and the segment name is '/dev/sdb1'. If the parcel isn't made then select that plate and make segment-first utilizing the 'disk' utility and you can do it inside the compartment as the holder is running in favored mode.

Step 3: Now, create a folder to mount this partition over there:

mkdir /mnt/my-data

Step 4: Let’s go ahead and mount this partition to the container and write some data into it as shown below: –

mount /dev/sdb1 /mnt/my-data

Step 5: Change directory to ‘/mnt/my data and create a text file named ‘test.txt’ and also populate some data into it as shown below: –

cd /mnt/my-data
cat >> test.txt

It is a test file.

^Z(press ctrl + Z)
cat test.txt

In the above snapshot, we have created a test file and added some text to it, now we are going to exit from this container and mount the same disk partition to the host and try to access that file.

Step 6: Exit from the container and run the below command to mount the disk partition ‘/dev/sdb1’ to the host:

sudo mount /dev/sdb1 /mnt/disk2
cd /mnt/disk2
ls
cat test.txt

In the above snapshot, we have mounted the disk partition to an existing folder that is ‘/mnt/disk2’, you can mount it at any folder location you want and sure enough, we can access the file created inside the container.

Scenario 2:

Use the ‘–cap-add’ and ‘–cap-drop’ options to add and limit the capabilities of the container respectively.

Step 1: We can use the ‘–Capaldi with the value ‘ALL’ to provide all capabilities because there are a default list of capabilities that are allowed by default but we have a situation where we want to drop one capability so we have to also use the ‘–cap-drop’ option to remove that capability as shown below: –

docker run -it --rm --privileged --cap-add=ALL --cap-drop=MKNOD ubuntu sh

In the above preview, we have added all abilities except the 'MKNOD' which will keep from making unique documents utilizing my node. We have run the 'fdisk - I'm to make sure that the compartment is running under honor mode.

Notes:

  • Any command that requires a privilege flag to be successful can be used to test the privilege mode inside the container.
  • We can inspect the container to know if that container is running in privileged mode or not using the below command:
docker inspect --format='{{.HostConfig.Privileged}}' <container id>

Advantages:

  • It gives comparative admittance to the host to the holder running in advantaged mode.
  • It likewise permits to run of Docker in Docker with this mode.
  • We can give Docker-as-a-Service assuming somebody needs their own private Docker example.

Conclusion:

Docker advantaged mode is incredible in a couple of situations, notwithstanding, we ought to be mindful of its dangers as we can do anything from inside the holder, even it can obliterate the segment on which the host machine is running. It is prescribed to restrict access utilizing other accessible banners.

Docker
Docker Privileged
DevOps
Docker secrets
Docker secrets
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