AppArmor policy to deny network packets is not working

[rayandasoriya]

Description

The AppArmor policy to deny network packets is not working in v20.10.13 and v20.10.14 for Ubuntu docker image. It was working in v20.10.12.

Steps to reproduce the issue:

1. Use docker version v20.10.14
2. Create an AppArmor policy:

cat > /tmp/no_ping <<EOF
#include <tunables/global>

profile no-ping flags=(attach_disconnected,mediate_deleted) {
  #include <abstractions/base>

  network inet tcp,
  network inet udp,
  network inet icmp,

  deny network raw,
  deny network packet,
  file,
  mount,
}
EOF

3. Load the profile in AppArmor /sbin/apparmor_parser --replace --write-cache /tmp/no_ping
4. Create a Dockerfile with Ubuntu 22.04 and ping capabilities:

cat > Dockerfile <<EOF
FROM ubuntu:22.04
RUN apt-get update && apt install -y iputils-ping
EOF

5. Create a docker image using docker build -t ubuntu-test .
6. Run a container with the policy docker run --rm -i --security-opt apparmor=no-ping ubuntu-test:latest ping -c3 8.8.8.8

Describe the results you received:

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=114 time=1.54 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=114 time=1.44 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=114 time=1.34 ms

--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 1.346/1.444/1.541/0.079 ms

Describe the results you expected:

ping: icmp open socket: Permission denied

Additional information you deem important (e.g. issue happens only occasionally):

This was a working solution till Docker v20.10.12. Also, the above workflow is not working for an Ubuntu image but is working for debian(debian:jessie).

Output of docker version:

$ sudo docker version
Client: Docker Engine - Community
 Version:           20.10.14
 API version:       1.41
 Go version:        go1.16.15
 Git commit:        a224086
 Built:             Thu Mar 24 01:47:47 2022
 OS/Arch:           linux/amd64
 Context:           default
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          20.10.14
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.16.15
  Git commit:       87a90dc
  Built:            Thu Mar 24 01:45:38 2022
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.5.11
  GitCommit:        3df54a852345ae127d1fa3092b95168e4a88e2f8
 runc:
  Version:          1.0.3
  GitCommit:        v1.0.3-0-gf46b6ba
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

Output of docker info:

$ sudo docker info
Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Docker Buildx (Docker Inc., v0.8.1-docker)
  compose: Docker Compose (Docker Inc., v2.3.3)
  scan: Docker Scan (Docker Inc., v0.17.0)

Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 3
 Server Version: 20.10.14
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 3df54a852345ae127d1fa3092b95168e4a88e2f8
 runc version: v1.0.3-0-gf46b6ba
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: default
  cgroupns
 Kernel Version: 5.15.0-1003-gcp
 Operating System: Ubuntu 22.04 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 3.831GiB
 Name: ubuntu-test-1
 ID: JBHY:6IDZ:ZKK5:WHT6:YHK3:WKF7:UVXL:SZT2:3BZD:IMKG:ZLGB:CGAG
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

Additional environment details (AWS, VirtualBox, physical, etc.):

Running Ubuntu 22.04 LTS on GCP.

[thaJeztah]

Looks related to

• [20.10 backport] daemon.WithCommonOptions() fix detection of user-namespaces #43084
• Add default sysctls to allow ping sockets and privileged ports with no capabilities #41030

[rayandasoriya]

Thanks @thaJeztah. Updating the policy to deny icmp packages fixed the issue.

[thaJeztah]

Good to hear that helped!

[vteratipally]

/reopen

[vteratipally]

This issue is happening in docker 23.0.0-rc.3