From 316d653d3e0530d11f7f3a8a6b3f8cf97daaf0f8 Mon Sep 17 00:00:00 2001 From: Slavi Pantaleev Date: Mon, 28 Jan 2019 11:22:54 +0200 Subject: [PATCH] Drop capabilities in containers We run containers as a non-root user (no effective capabilities). Still, if a setuid binary is available in a container image, it could potentially be used to give the user the default capabilities that the container was started with. For Docker, the default set currently is: - "CAP_CHOWN" - "CAP_DAC_OVERRIDE" - "CAP_FSETID" - "CAP_FOWNER" - "CAP_MKNOD" - "CAP_NET_RAW" - "CAP_SETGID" - "CAP_SETUID" - "CAP_SETFCAP" - "CAP_SETPCAP" - "CAP_NET_BIND_SERVICE" - "CAP_SYS_CHROOT" - "CAP_KILL" - "CAP_AUDIT_WRITE" We'd rather prevent such a potential escalation by dropping ALL capabilities. The problem is nicely explained here: https://github.com/projectatomic/atomic-site/issues/203 --- .../matrix-corporal/templates/systemd/matrix-corporal.service.j2 | 1 + roles/matrix-coturn/templates/systemd/matrix-coturn.service.j2 | 1 + roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 | 1 + roles/matrix-mxisd/templates/systemd/matrix-mxisd.service.j2 | 1 + .../templates/systemd/matrix-nginx-proxy.service.j2 | 1 + .../matrix-postgres/templates/systemd/matrix-postgres.service.j2 | 1 + .../matrix-riot-web/templates/systemd/matrix-riot-web.service.j2 | 1 + .../templates/synapse/systemd/matrix-synapse.service.j2 | 1 + 8 files changed, 8 insertions(+) diff --git a/roles/matrix-corporal/templates/systemd/matrix-corporal.service.j2 b/roles/matrix-corporal/templates/systemd/matrix-corporal.service.j2 index eb11890d..3d8c083f 100644 --- a/roles/matrix-corporal/templates/systemd/matrix-corporal.service.j2 +++ b/roles/matrix-corporal/templates/systemd/matrix-corporal.service.j2 @@ -12,6 +12,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-corporal ExecStart=/usr/bin/docker run --rm --name matrix-corporal \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ --network={{ matrix_docker_network }} \ {% if matrix_corporal_container_expose_ports %} -p 127.0.0.1:41080:41080 \ diff --git a/roles/matrix-coturn/templates/systemd/matrix-coturn.service.j2 b/roles/matrix-coturn/templates/systemd/matrix-coturn.service.j2 index 69bd5eb8..cf2c096e 100644 --- a/roles/matrix-coturn/templates/systemd/matrix-coturn.service.j2 +++ b/roles/matrix-coturn/templates/systemd/matrix-coturn.service.j2 @@ -12,6 +12,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-coturn ExecStart=/usr/bin/docker run --rm --name matrix-coturn \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ -p 3478:3478 \ -p 3478:3478/udp \ -p {{ matrix_coturn_turn_udp_min_port }}-{{ matrix_coturn_turn_udp_max_port }}:{{ matrix_coturn_turn_udp_min_port }}-{{ matrix_coturn_turn_udp_max_port }}/udp \ diff --git a/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 b/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 index e6d79857..d588ac0e 100644 --- a/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 +++ b/roles/matrix-mailer/templates/systemd/matrix-mailer.service.j2 @@ -10,6 +10,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-mailer ExecStart=/usr/bin/docker run --rm --name matrix-mailer \ --log-driver=none \ --user={{ matrix_mailer_container_user_uid }}:{{ matrix_mailer_container_user_gid }} \ + --cap-drop=ALL \ --network={{ matrix_docker_network }} \ --env-file={{ matrix_mailer_base_path }}/env-mailer \ --hostname={{ hostname_matrix }} \ diff --git a/roles/matrix-mxisd/templates/systemd/matrix-mxisd.service.j2 b/roles/matrix-mxisd/templates/systemd/matrix-mxisd.service.j2 index 978a85c1..1835301a 100644 --- a/roles/matrix-mxisd/templates/systemd/matrix-mxisd.service.j2 +++ b/roles/matrix-mxisd/templates/systemd/matrix-mxisd.service.j2 @@ -15,6 +15,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-mxisd ExecStart=/usr/bin/docker run --rm --name matrix-mxisd \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ --network={{ matrix_docker_network }} \ {% if matrix_mxisd_container_expose_port %} -p 127.0.0.1:8090:8090 \ diff --git a/roles/matrix-nginx-proxy/templates/systemd/matrix-nginx-proxy.service.j2 b/roles/matrix-nginx-proxy/templates/systemd/matrix-nginx-proxy.service.j2 index 7bfade3d..810797d7 100644 --- a/roles/matrix-nginx-proxy/templates/systemd/matrix-nginx-proxy.service.j2 +++ b/roles/matrix-nginx-proxy/templates/systemd/matrix-nginx-proxy.service.j2 @@ -15,6 +15,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-nginx-proxy ExecStart=/usr/bin/docker run --rm --name matrix-nginx-proxy \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ --network={{ matrix_docker_network }} \ -p 80:8080 \ -p 443:8443 \ diff --git a/roles/matrix-postgres/templates/systemd/matrix-postgres.service.j2 b/roles/matrix-postgres/templates/systemd/matrix-postgres.service.j2 index 40509e8c..89b5abb8 100644 --- a/roles/matrix-postgres/templates/systemd/matrix-postgres.service.j2 +++ b/roles/matrix-postgres/templates/systemd/matrix-postgres.service.j2 @@ -10,6 +10,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-postgres ExecStart=/usr/bin/docker run --rm --name matrix-postgres \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ --network={{ matrix_docker_network }} \ --env-file={{ matrix_postgres_base_path }}/env-postgres-server \ -v {{ matrix_postgres_data_path }}:/var/lib/postgresql/data \ diff --git a/roles/matrix-riot-web/templates/systemd/matrix-riot-web.service.j2 b/roles/matrix-riot-web/templates/systemd/matrix-riot-web.service.j2 index 28228e23..e7929489 100644 --- a/roles/matrix-riot-web/templates/systemd/matrix-riot-web.service.j2 +++ b/roles/matrix-riot-web/templates/systemd/matrix-riot-web.service.j2 @@ -12,6 +12,7 @@ ExecStartPre=-/usr/bin/docker rm matrix-riot-web ExecStart=/usr/bin/docker run --rm --name matrix-riot-web \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ -v {{ matrix_riot_web_data_path }}/nginx.conf:/etc/nginx/nginx.conf:ro \ -v /dev/null:/etc/nginx/conf.d/default.conf:ro \ -v {{ matrix_riot_web_data_path }}/config.json:/etc/riot-web/config.json:ro \ diff --git a/roles/matrix-synapse/templates/synapse/systemd/matrix-synapse.service.j2 b/roles/matrix-synapse/templates/synapse/systemd/matrix-synapse.service.j2 index 05023642..79b3478c 100644 --- a/roles/matrix-synapse/templates/synapse/systemd/matrix-synapse.service.j2 +++ b/roles/matrix-synapse/templates/synapse/systemd/matrix-synapse.service.j2 @@ -21,6 +21,7 @@ ExecStartPre=/bin/sleep 5 ExecStart=/usr/bin/docker run --rm --name matrix-synapse \ --log-driver=none \ --user={{ matrix_user_uid }}:{{ matrix_user_gid }} \ + --cap-drop=ALL \ --entrypoint=python \ --network={{ matrix_docker_network }} \ -e SYNAPSE_CACHE_FACTOR={{ matrix_synapse_cache_factor }} \