3 - Gate: dockerfile
Introduction
This article reviews the “dockerfile” gate and its triggers. The dockerfile gate allows users to perform checks on the content of the dockerfile or docker history for an image and make policy actions based on the construction of an image, not just its content. This is particularly useful for enforcing best practices or metadata inclusion (e.g. labels) on images.
Anchore is either given a dockerfile or infers one from the docker image layer history. There are implications to what data is available and what it means depending on these differing sources, so first, we’ll cover the input data for the gate and how it impacts the triggers and parameters used.
The “dockerfile”
The data that this gate operates on can come from two different sources:
- The actual dockerfile used to build an image, as provided by the user at the time of running
anchorectl image add <img ref> --dockerfile <filename> or the corresponding API call to: POST /images?dockerfile= - The history from layers as encoded in the image itself (see
docker history <img> for this output)
All images have data from history available, but data from the actual dockerfile is only available when a user provides it. This also means that any images analyzed by the tag watcher functionality will not have an actual dockerfile.
The FROM line
In the actual dockerfile, the FROM instruction is preserved and available as used to build the image, however in the history data, the FROM line will always be the very first FROM instruction used to build the image and all of its dependent based image. Thus, for most images, the value in the history will be omitted and Anchore will automatically infer a FROM scratch line, which is logically inserted for this gate if the dockerfile/history does not contain an explicit FROM entry.
For example, using the docker.io/jenkins/jenkins image:
IMAGE CREATED CREATED BY SIZE COMMENT
sha256:3b9c9666a66e53473c05a3c69eb2cb888a8268f76935eecc7530653cddc28981 11 hours ago /bin/sh -c #(nop) COPY file:3a15c25533fd87983edc33758f62af7b543ccc3ce9dd570e473eb0702f5f298e in /usr/local/bin/install-plugins.sh 8.79kB
<missing> 11 hours ago /bin/sh -c #(nop) COPY file:f97999fac8a63cf8b635a54ea84a2bc95ae3da4d81ab55267c92b28b502d8812 in /usr/local/bin/plugins.sh 3.96kB
<missing> 11 hours ago /bin/sh -c #(nop) ENTRYPOINT ["/sbin/tini" "--" "/usr/local/bin/jenkins.sh"] 0B
<missing> 11 hours ago /bin/sh -c #(nop) COPY file:dc942ca949bb159f81bbc954773b3491e433d2d3e3ef90bac80ecf48a313c9c9 in /bin/tini 529B
<missing> 11 hours ago /bin/sh -c #(nop) COPY file:a8f986413b77bf4d88562b9d3a0dce98ab6e75403192aa4d4153fb41f450843d in /usr/local/bin/jenkins.sh 1.45kB
<missing> 11 hours ago /bin/sh -c #(nop) COPY file:55594d9d2aed007553a6743a43039b1a48b30527f8fb991ad93e1fd5b1298f60 in /usr/local/bin/jenkins-support 6.12kB
<missing> 11 hours ago /bin/sh -c #(nop) USER jenkins 0B
<missing> 11 hours ago /bin/sh -c #(nop) ENV COPY_REFERENCE_FILE_LOG=/var/jenkins_home/copy_reference_file.log 0B
<missing> 11 hours ago /bin/sh -c #(nop) EXPOSE 50000 0B
<missing> 11 hours ago /bin/sh -c #(nop) EXPOSE 8080 0B
<missing> 11 hours ago |9 JENKINS_SHA=e026221efcec9528498019b6c1581cca70fe9c3f6b10303777d85c6699bca0e4 JENKINS_URL=https://repo.jenkins-ci.org/public/org/jenkins-ci/main/jenkins-war/2.161/jenkins-war-2.161.war TINI_VERSION=v0.16.1 agent_port=50000 gid=1000 group=jenkins http_port=8080 uid=1000 user=jenkins /bin/sh -c chown -R ${user} "$JENKINS_HOME" /usr/share/jenkins/ref 328B
<missing> 11 hours ago /bin/sh -c #(nop) ENV JENKINS_INCREMENTALS_REPO_MIRROR=https://repo.jenkins-ci.org/incrementals 0B
<missing> 11 hours ago /bin/sh -c #(nop) ENV JENKINS_UC_EXPERIMENTAL=https://updates.jenkins.io/experimental 0B
<missing> 11 hours ago /bin/sh -c #(nop) ENV JENKINS_UC=https://updates.jenkins.io 0B
<missing> 11 hours ago |9 JENKINS_SHA=e026221efcec9528498019b6c1581cca70fe9c3f6b10303777d85c6699bca0e4 JENKINS_URL=https://repo.jenkins-ci.org/public/org/jenkins-ci/main/jenkins-war/2.161/jenkins-war-2.161.war TINI_VERSION=v0.16.1 agent_port=50000 gid=1000 group=jenkins http_port=8080 uid=1000 user=jenkins /bin/sh -c curl -fsSL ${JENKINS_URL} -o /usr/share/jenkins/jenkins.war && echo "${JENKINS_SHA} /usr/share/jenkins/jenkins.war" | sha256sum -c - 76MB
<missing> 11 hours ago /bin/sh -c #(nop) ARG JENKINS_URL=https://repo.jenkins-ci.org/public/org/jenkins-ci/main/jenkins-war/2.161/jenkins-war-2.161.war 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG JENKINS_SHA=5bb075b81a3929ceada4e960049e37df5f15a1e3cfc9dc24d749858e70b48919 0B
<missing> 11 hours ago /bin/sh -c #(nop) ENV JENKINS_VERSION=2.161 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG JENKINS_VERSION 0B
<missing> 11 hours ago /bin/sh -c #(nop) COPY file:c84b91c835048a52bb864c1f4662607c56befe3c4b1520b0ea94633103a4554f in /usr/share/jenkins/ref/init.groovy.d/tcp-slave-agent-port.groovy 328B
<missing> 11 hours ago |7 TINI_VERSION=v0.16.1 agent_port=50000 gid=1000 group=jenkins http_port=8080 uid=1000 user=jenkins /bin/sh -c curl -fsSL https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini-static-$(dpkg --print-architecture) -o /sbin/tini && curl -fsSL https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini-static-$(dpkg --print-architecture).asc -o /sbin/tini.asc && gpg --no-tty --import ${JENKINS_HOME}/tini_pub.gpg && gpg --verify /sbin/tini.asc && rm -rf /sbin/tini.asc /root/.gnupg && chmod +x /sbin/tini 866kB
<missing> 11 hours ago /bin/sh -c #(nop) COPY file:653491cb486e752a4c2b4b407a46ec75646a54eabb597634b25c7c2b82a31424 in /var/jenkins_home/tini_pub.gpg 7.15kB
<missing> 11 hours ago /bin/sh -c #(nop) ARG TINI_VERSION=v0.16.1 0B
<missing> 11 hours ago |6 agent_port=50000 gid=1000 group=jenkins http_port=8080 uid=1000 user=jenkins /bin/sh -c mkdir -p /usr/share/jenkins/ref/init.groovy.d 0B
<missing> 11 hours ago /bin/sh -c #(nop) VOLUME [/var/jenkins_home] 0B
<missing> 11 hours ago |6 agent_port=50000 gid=1000 group=jenkins http_port=8080 uid=1000 user=jenkins /bin/sh -c mkdir -p $JENKINS_HOME && chown ${uid}:${gid} $JENKINS_HOME && groupadd -g ${gid} ${group} && useradd -d "$JENKINS_HOME" -u ${uid} -g ${gid} -m -s /bin/bash ${user} 328kB
<missing> 11 hours ago /bin/sh -c #(nop) ENV JENKINS_SLAVE_AGENT_PORT=50000 0B
<missing> 11 hours ago /bin/sh -c #(nop) ENV JENKINS_HOME=/var/jenkins_home 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG JENKINS_HOME=/var/jenkins_home 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG agent_port=50000 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG http_port=8080 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG gid=1000 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG uid=1000 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG group=jenkins 0B
<missing> 11 hours ago /bin/sh -c #(nop) ARG user=jenkins 0B
<missing> 11 hours ago /bin/sh -c apt-get update && apt-get install -y git curl && rm -rf /var/lib/apt/lists/* 0B
<missing> 3 weeks ago /bin/sh -c set -ex; if [ ! -d /usr/share/man/man1 ]; then mkdir -p /usr/share/man/man1; fi; apt-get update; apt-get install -y --no-install-recommends openjdk-8-jdk="$JAVA_DEBIAN_VERSION" ; rm -rf /var/lib/apt/lists/*; [ "$(readlink -f "$JAVA_HOME")" = "$(docker-java-home)" ]; update-alternatives --get-selections | awk -v home="$(readlink -f "$JAVA_HOME")" 'index($3, home) == 1 { $2 = "manual"; print | "update-alternatives --set-selections" }'; update-alternatives --query java | grep -q 'Status: manual' 348MB
<missing> 3 weeks ago /bin/sh -c #(nop) ENV JAVA_DEBIAN_VERSION=8u181-b13-2~deb9u1 0B
<missing> 3 weeks ago /bin/sh -c #(nop) ENV JAVA_VERSION=8u181 0B
<missing> 3 weeks ago /bin/sh -c #(nop) ENV JAVA_HOME=/docker-java-home 0B
<missing> 3 weeks ago /bin/sh -c ln -svT "/usr/lib/jvm/java-8-openjdk-$(dpkg --print-architecture)" /docker-java-home 33B
<missing> 3 weeks ago /bin/sh -c { echo '#!/bin/sh'; echo 'set -e'; echo; echo 'dirname "$(dirname "$(readlink -f "$(which javac || which java)")")"'; } > /usr/local/bin/docker-java-home && chmod +x /usr/local/bin/docker-java-home 87B
<missing> 3 weeks ago /bin/sh -c #(nop) ENV LANG=C.UTF-8 0B
<missing> 3 weeks ago /bin/sh -c apt-get update && apt-get install -y --no-install-recommends bzip2 unzip xz-utils && rm -rf /var/lib/apt/lists/* 2.21MB
<missing> 3 weeks ago /bin/sh -c apt-get update && apt-get install -y --no-install-recommends bzr git mercurial openssh-client subversion procps && rm -rf /var/lib/apt/lists/* 142MB
<missing> 3 weeks ago /bin/sh -c set -ex; if ! command -v gpg > /dev/null; then apt-get update; apt-get install -y --no-install-recommends gnupg dirmngr ; rm -rf /var/lib/apt/lists/*; fi 7.81MB
<missing> 3 weeks ago /bin/sh -c apt-get update && apt-get install -y --no-install-recommends ca-certificates curl netbase wget && rm -rf /var/lib/apt/lists/* 23.2MB
<missing> 3 weeks ago /bin/sh -c #(nop) CMD ["bash"] 0B
<missing> 3 weeks ago /bin/sh -c #(nop) ADD file:da71baf0d22cb2ede91c5e3ff959607e47459a9d7bda220a62a3da362b0e59ea in / 101MB
Where the actual dockerfile for that image is:
FROM openjdk:8-jdk-stretch
RUN apt-get update && apt-get install -y git curl && rm -rf /var/lib/apt/lists/*
ARG user=jenkins
ARG group=jenkins
ARG uid=1000
ARG gid=1000
ARG http_port=8080
ARG agent_port=50000
ARG JENKINS_HOME=/var/jenkins_home
ENV JENKINS_HOME $JENKINS_HOME
ENV JENKINS_SLAVE_AGENT_PORT ${agent_port}
# Jenkins is run with user `jenkins`, uid = 1000
# If you bind mount a volume from the host or a data container,
# ensure you use the same uid
RUN mkdir -p $JENKINS_HOME \
&& chown ${uid}:${gid} $JENKINS_HOME \
&& groupadd -g ${gid} ${group} \
&& useradd -d "$JENKINS_HOME" -u ${uid} -g ${gid} -m -s /bin/bash ${user}
# Jenkins home directory is a volume, so configuration and build history
# can be persisted and survive image upgrades
VOLUME $JENKINS_HOME
# `/usr/share/jenkins/ref/` contains all reference configuration we want
# to set on a fresh new installation. Use it to bundle additional plugins
# or config file with your custom jenkins Docker image.
RUN mkdir -p /usr/share/jenkins/ref/init.groovy.d
# Use tini as subreaper in Docker container to adopt zombie processes
ARG TINI_VERSION=v0.16.1
COPY tini_pub.gpg ${JENKINS_HOME}/tini_pub.gpg
RUN curl -fsSL https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini-static-$(dpkg --print-architecture) -o /sbin/tini \
&& curl -fsSL https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini-static-$(dpkg --print-architecture).asc -o /sbin/tini.asc \
&& gpg --no-tty --import ${JENKINS_HOME}/tini_pub.gpg \
&& gpg --verify /sbin/tini.asc \
&& rm -rf /sbin/tini.asc /root/.gnupg \
&& chmod +x /sbin/tini
COPY init.groovy /usr/share/jenkins/ref/init.groovy.d/tcp-slave-agent-port.groovy
# jenkins version being bundled in this docker image
ARG JENKINS_VERSION
ENV JENKINS_VERSION ${JENKINS_VERSION:-2.121.1}
# jenkins.war checksum, download will be validated using it
ARG JENKINS_SHA=5bb075b81a3929ceada4e960049e37df5f15a1e3cfc9dc24d749858e70b48919
# Can be used to customize where jenkins.war get downloaded from
ARG JENKINS_URL=https://repo.jenkins-ci.org/public/org/jenkins-ci/main/jenkins-war/${JENKINS_VERSION}/jenkins-war-${JENKINS_VERSION}.war
# could use ADD but this one does not check Last-Modified header neither does it allow to control checksum
# see https://github.com/docker/docker/issues/8331
RUN curl -fsSL ${JENKINS_URL} -o /usr/share/jenkins/jenkins.war \
&& echo "${JENKINS_SHA} /usr/share/jenkins/jenkins.war" | sha256sum -c -
ENV JENKINS_UC https://updates.jenkins.io
ENV JENKINS_UC_EXPERIMENTAL=https://updates.jenkins.io/experimental
ENV JENKINS_INCREMENTALS_REPO_MIRROR=https://repo.jenkins-ci.org/incrementals
RUN chown -R ${user} "$JENKINS_HOME" /usr/share/jenkins/ref
# for main web interface:
EXPOSE ${http_port}
# will be used by attached slave agents:
EXPOSE ${agent_port}
ENV COPY_REFERENCE_FILE_LOG $JENKINS_HOME/copy_reference_file.log
USER ${user}
COPY jenkins-support /usr/local/bin/jenkins-support
COPY jenkins.sh /usr/local/bin/jenkins.sh
COPY tini-shim.sh /bin/tini
ENTRYPOINT ["/sbin/tini", "--", "/usr/local/bin/jenkins.sh"]
# from a derived Dockerfile, can use `RUN plugins.sh active.txt` to setup /usr/share/jenkins/ref/plugins from a support bundle
COPY plugins.sh /usr/local/bin/plugins.sh
COPY install-plugins.sh /usr/local/bin/install-plugins.sh
Anchore will detect the history/dockerfile as this, if not explicitly provided (note order is reversed from docker history output, so it reads in same order as actual dockerfile):
[
{
"Size" : 45323792,
"Tags" : [],
"Comment" : "",
"Id" : "sha256:cd8eada9c7bb496eb685fc6d2198c33db7cb05daf0fde42e4cf5bf0127cbdf38",
"Created" : "2018-12-28T23:29:37.981962131Z",
"CreatedBy" : "/bin/sh -c #(nop) ADD file:da71baf0d22cb2ede91c5e3ff959607e47459a9d7bda220a62a3da362b0e59ea in / "
},
{
"Size" : 0,
"Tags" : [],
"Comment" : "",
"Id" : "<missing>",
"Created" : "2018-12-28T23:29:38.226681736Z",
"CreatedBy" : "/bin/sh -c #(nop) CMD [\"bash\"]"
},
{
"Size" : 10780911,
"Comment" : "",
"Tags" : [],
"CreatedBy" : "/bin/sh -c apt-get update && apt-get install -y --no-install-recommends \t\tca-certificates \t\tcurl \t\tnetbase \t\twget \t&& rm -rf /var/lib/apt/lists/*",
"Created" : "2018-12-29T00:04:28.920875483Z",
"Id" : "sha256:c2677faec825930a8844845f55454ee0495ceb5bea9fc904d5b3125de863dc1d"
},
{
"Comment" : "",
"Tags" : [],
"Size" : 4340024,
"CreatedBy" : "/bin/sh -c set -ex; \tif ! command -v gpg > /dev/null; then \t\tapt-get update; \t\tapt-get install -y --no-install-recommends \t\t\tgnupg \t\t\tdirmngr \t\t; \t\trm -rf /var/lib/apt/lists/*; \tfi",
"Created" : "2018-12-29T00:04:34.642152001Z",
"Id" : "sha256:fcce419a96b1219a265bf7a933d66b585a6f8d73448533f3833c73ad49fb5e88"
},
{
"Size" : 50062697,
"Tags" : [],
"Comment" : "",
"Id" : "sha256:045b51e26e750443c84216071a1367a7aae0b76245800629dc04934628b4b1ea",
"CreatedBy" : "/bin/sh -c apt-get update && apt-get install -y --no-install-recommends \t\tbzr \t\tgit \t\tmercurial \t\topenssh-client \t\tsubversion \t\t\t\tprocps \t&& rm -rf /var/lib/apt/lists/*",
"Created" : "2018-12-29T00:04:59.676112605Z"
},
... <truncated for brevity> ...
{
"Tags" : [],
"Comment" : "",
"Size" : 0,
"Id" : "<missing>",
"CreatedBy" : "/bin/sh -c #(nop) ENTRYPOINT [\"/sbin/tini\" \"--\" \"/usr/local/bin/jenkins.sh\"]",
"Created" : "2019-01-21T08:56:30.737221895Z"
},
{
"Size" : 1549,
"Tags" : [],
"Comment" : "",
"Id" : "sha256:283cd3aba8691a3b9d22d923de66243b105758e74de7d9469fe55a6a58aeee30",
"Created" : "2019-01-21T08:56:32.015667468Z",
"CreatedBy" : "/bin/sh -c #(nop) COPY file:f97999fac8a63cf8b635a54ea84a2bc95ae3da4d81ab55267c92b28b502d8812 in /usr/local/bin/plugins.sh "
},
{
"Comment" : "",
"Tags" : [],
"Size" : 3079,
"Created" : "2019-01-21T08:56:33.158854485Z",
"CreatedBy" : "/bin/sh -c #(nop) COPY file:3a15c25533fd87983edc33758f62af7b543ccc3ce9dd570e473eb0702f5f298e in /usr/local/bin/install-plugins.sh ",
"Id" : "sha256:b0ce8ab5a5a7da5d762f25af970f4423b98437a8318cb9852c3f21354cbf914f"
}
]
NOTE: Anchore processes the leading /bin/sh commands, so you do not have to include those in any trigger param config if using the docker history output.
The actual_dockerfile_only Parameter
The actual vs history impacts the semantics of the dockerfile gate’s triggers. To allow explicit control of the differences, most triggers in this gate includes a parameter: actual_dockerfile_only that if set to true or false will ensure the trigger check is only done on the source of data specified. If actual_dockerfile_only = true, then the trigger will evaluate only if an actual dockerfile is available for the image and will skip evaluation if not. If actual_dockerfile_only is false or omitted, then the trigger will run on the actual dockerfile if available, or the history data if the dockerfile was not provided.
Differences in data between Docker History and actual Dockerfile
With Actual Dockerfile:
- FROM line is preserved, so the parent tag of the image is easily available
- Instruction checks are all against instructions created during the build for that exact image, not any parent images
- When the actual_dockerfile_only parameter is set to true, all instructions from the parent image are ignored in policy processing. This may have some unexpected consequences depending on how your images are structured and layered (e.g. golden base images that establish common patterns of volumes, labels, healthchecks)
- COPY/ADD instructions will maintain the actual values used
- Multistage-builds in that specific dockerfile will be visible with multiple FROM lines in the output
With Docker History data, when no dockerfile is provided:
- FROM line is not accurate, and will nearly always default to ‘FROM scratch’
- Instructions are processed from all layers in the image
- COPY and ADD instructions are transformed into SHAs rather than the actual file path/name used at build-time
- Multi-stage builds are not tracked with multiple FROM lines, only the copy operations between the phases
Trigger: instruction
This trigger evaluates instructions found in the “dockerfile”.
Parameters
actual_dockerfile_only (optional): See above
instruction: The dockerfile instruction to check against. One of:
- ADD
- ARG
- COPY
- CMD
- ENTRYPOINT
- ENV
- EXPOSE
- FROM
- HEALTHCHECK
- LABEL
- MAINTAINER
- ONBUILD
- USER
- RUN
- SHELL
- STOPSIGNAL
- VOLUME
- WORKDIR
check: The comparison/evaluation to perform. One of: =, != , exists, not_exists, like, not_like, in, not_in.
value (optional): A string value to compare against, if applicable.
Examples
- Ensure an image has a HEALTHCHECK defined in the image (warn if not found).
{
"gate": "dockerfile",
"trigger": "instruction",
"action": "warn",
"parameters": [
{
"name": "instruction",
"value": "HEALTHCHECK"
},
{
"name": "check",
"value": "not_exists"
}
]
}
- Check for AWS environment variables set.
{
"gate": "dockerfile",
"trigger": "instruction",
"action": "stop",
"parameters": [
{
"name": "instruction",
"value": "ENV"
},
{
"name": "check",
"value": "like"
},
{
"name": "value",
"value": "AWS_.*KEY"
}
]
}
Trigger: effective_user
This trigger processes all USER directives in the dockerfile or history to determine which user will be used to run the container by default (assuming no user is set explicitly at runtime). The detected value is then subject to a allowlist or denylist filter depending on the configured parameters. Typically, this is used for denylisting the root user.
Parameters
actual_dockerfile_only (optional): See above
users: A string with a comma delimited list of username to check for.
type: The type of check to perform. One of: ‘denylist’ or ‘allowlist’. This determines how the value of the ‘users’ parameter is interpreted.
Examples
- Denylist root user.
{
"gate": "dockerfile",
"trigger": "effective_user",
"action": "stop",
"parameters": [
{
"name": "users",
"value": "root"
},
{
"name": "type",
"value": "denylist"
}
]
}
- Denylist root user but only if set in actual dockerfile, not inherited from parent image.
{
"gate": "dockerfile",
"trigger": "effective_user",
"action": "stop",
"parameters": [
{
"name": "users",
"value": "root"
},
{
"name": "type",
"value": "denylist"
},
{
"name": "actual_dockerfile_only",
"value": "true"
}
]
}
- Warn if the user is not either “nginx” or “jenkins”.
{
"gate": "dockerfile",
"trigger": "effective_user",
"action": "warn",
"parameters": [
{
"name": "users",
"value": "nginx,jenkins"
},
{
"name": "type",
"value": "allowlist"
}
]
}
Trigger: exposed_ports
This trigger processes the set of EXPOSE directives in the dockerfile/history to determine the set of ports that are defined to be exposed (since it can span multiple directives). It performs checks on that set to denylist/allowlist them based on parameter settings.
Parameters
actual_dockerfile_only (optional): See above
ports: String of comma delimited port numbers to be checked.
type: The type of check to perform. One of: ‘denylist’ or ‘allowlist’. This determines how the value of the ‘users’ parameter is interpreted.
Examples
- Allow only ports 80 and 443. Trigger will fire on any port defined to be exposed that is not 80 or 443.
{
"gate": "dockerfile",
"trigger": "exposed_ports",
"action": "warn",
"parameters": [
{
"name": "ports",
"value": "80,443"
},
{
"name": "type",
"value": "allowlist"
}
]
}
- Denylist ports 21 (ftp), 22 (ssh), and 53 (dns) . Trigger will fire a match on ports 21, 22, 53 if found in EXPOSE directives.
{
"gate": "dockerfile",
"trigger": "exposed_ports",
"action": "warn",
"parameters": [
{
"name": "ports",
"value": "21,22,53"
},
{
"name": "type",
"value": "denylist"
}
]
}
Trigger: no_dockerfile_provided
This trigger allows checks on the way the image was added, firing if the dockerfile was not explicitly provided at analysis time. This is useful in identifying and qualifying other trigger matches.
Parameters
None
Examples
- Raise a warning if no dockerfile was provided at analysis time .
{
"gate": "dockerfile",
"trigger": "no_dockerfile_provided",
"action": "warn",
"parameters": []
}
More Example Use-cases
Scenario 1
Goal: Create a rule that results in a STOP action for username “root” found in an image SBOM’s dockerfile “USER” line.
Example rule set configuration in Anchore Enterprise
Gate: dockerfile
Trigger: effective_user
Required Parameters: users = “root”, type = “denylist”
Recommendations (optional): “The username “root” is found in USER line. Fix required.”
Action: STOP
Scenario 2
Goal: Create a rule that results in a WARN action for usernames “nginx” or “jenkins” not found in an image SBOM’s dockerfile “USER” line.
Example rule set configuration in Anchore Enterprise
Gate: dockerfile
Trigger: effective_user
Required Parameters: users = “nginx,jenkins”, type = “allowlist”
Action: WARN
Scenario 3
Goal: Create a rule that results in a STOP action for any exposed AWS key environment variable found in an image SBOM’s dockerfile.
Example rule set configuration in Anchore Enterprise
Gate: dockerfile
Trigger: instruction
Required Parameters: instruction = “env”, check = “like”
Optional Parameters: value = “AWS_.*KEY”
Recommendations (optional): “AWS environment variable key found, Removal required.”
Action: STOP
Reference: dockerfile
| Trigger Name | Description | Parameter | Description | Example |
|---|
| instruction | Triggers if any directives in the list are found to match the described condition in the dockerfile. | instruction | The Dockerfile instruction to check. | from |
| instruction | Triggers if any directives in the list are found to match the described condition in the dockerfile. | check | The type of check to perform. | = |
| instruction | Triggers if any directives in the list are found to match the described condition in the dockerfile. | value | The value to check the dockerfile instruction against. | scratch |
| instruction | Triggers if any directives in the list are found to match the described condition in the dockerfile. | actual_dockerfile_only | Only evaluate against a user-provided dockerfile, skip evaluation on inferred/guessed dockerfiles. Default is False. | true |
| effective_user | Checks if the effective user matches the provided user names, either as a allowlist or blocklist depending on the type parameter setting. | users | User names to check against as the effective user (last user entry) in the images history. | root,docker |
| effective_user | Checks if the effective user matches the provided user names, either as a allowlist or blocklist depending on the type parameter setting. | type | How to treat the provided user names. | denylist |
| exposed_ports | Evaluates the set of ports exposed. Allows configuring allowlist or blocklist behavior. If type=allowlist, then any ports found exposed that are not in the list will cause the trigger to fire. If type=denylist, then any ports exposed that are in the list will cause the trigger to fire. | ports | List of port numbers. | 80,8080,8088 |
| exposed_ports | Evaluates the set of ports exposed. Allows configuring allowlist or blocklist behavior. If type=allowlist, then any ports found exposed that are not in the list will cause the trigger to fire. If type=denylist, then any ports exposed that are in the list will cause the trigger to fire. | type | Whether to use port list as a allowlist or denylist. | denylist |
| exposed_ports | Evaluates the set of ports exposed. Allows configuring allowlist or blocklist behavior. If type=allowlist, then any ports found exposed that are not in the list will cause the trigger to fire. If type=denylist, then any ports exposed that are in the list will cause the trigger to fire. | actual_dockerfile_only | Only evaluate against a user-provided dockerfile, skip evaluation on inferred/guessed dockerfiles. Default is False. | true |
| no_dockerfile_provided | Triggers if anchore analysis was performed without supplying the actual image Dockerfile. | | | |
4 - Gate: files
Introduction
The “files” gate performs checks against the files in an analyzed image SBOM and is useful when users need to create policies that trigger against any matched file content, names and/or attributes.
Note The “files” gate differs from the “retrieved_files” gate. The “files” gate searches against the files present in an image SBOM whereas the “retrieved_files” gate utilizes Anchore’s cataloger capability and checks against files that are provided and stored by the user before analysis.
Example Use-cases
Scenario 1
Goal: Create a rule that results in a STOP action for any file name that contains “.pem”, which may include information such as the public certificate or even an entire certificate chain (public key, private key, and root certificates) of an image SBOM.
Example rule set configuration in Anchore Enterprise
Gate: files
Trigger: name match
Required Parameters: regex = “.*\.pem”
Recommendations (optional): “Filename with “.pem” found - Remediation required.”
Action: STOP
Scenario 2
Goal: Create a rule that results in a STOP action for any file that matches against regex string “.*password.*” in an image SBOM.
Note In order to use this gate, the analyzer_config.yaml file for your Anchore deployment must have specific regex strings configured under the content_search section as the rule will only check against regex strings that appear in this list. Please use the optional parameter “regex name” if you want to specify a single string for your policy rule. If this paramater is not configured, then every regex string stored in the content_search section in the analyzer_config.yaml will be checked against.
Example rule set configuration in Anchore Enterprise
Gate: files
Trigger: content regex match
Optional Parameters: regex name = “ABC”
Recommendations (optional): “Regex string “.*password.*” found in file. Fix required.”
Action: STOP
analyzer_config.yaml file
Reference: files
| Trigger Name | Description | Parameter | Description | Example |
|---|
| content_regex_match | Triggers for each file where the content search analyzer has found a match using configured regexes in the analyzer_config.yaml “content_search” section. If the parameter is set, the trigger will only fire for files that matched the named regex. Refer to your analyzer_config.yaml for the regex values. | regex_name | Regex string that also appears in the FILECHECK_CONTENTMATCH analyzer parameter in analyzer configuration, to limit the check to. If set, will only fire trigger when the specific named regex was found in a file. | .password. |
| name_match | Triggers if a file exists in the container that has a filename that matches the provided regex. This does have a performance impact on policy evaluation. | regex | Regex to apply to file names for match. | .*.pem |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | filename | Filename to check against provided checksum. | /etc/passwd |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | checksum_algorithm | Checksum algorithm | sha256 |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | checksum | Checksum of file. | 832cd0f75b227d13aac82b1f70b7f90191a4186c151f9db50851d209c45ede11 |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | checksum_match | Checksum operation to perform. | equals |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | mode | File mode of file. | 00644 |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | mode_op | File mode operation to perform. | equals |
| attribute_match | Triggers if a filename exists in the container that has attributes that match those which are provided . This check has a performance impact on policy evaluation. | skip_missing | If set to true, do not fire this trigger if the file is not present. If set to false, fire this trigger ignoring the other parameter settings. | true |
| suid_or_guid_set | Fires for each file found to have suid or sgid bit set. | | | |
14 - Gate: vulnerabilities
Introduction
The “vulnerabilities” gate provides users the ability to use either a single or combination of triggers and attributes that match against vulnerability metadata to create policies for the vulnerabilities discovered in an image SBOM.
Note Currently, only the following Triggers are available for Source Repository Rule Sets:
- Denylist
- Package
- Stale Feed Data
Example Use-cases
Scenario 1
Goal: Create a rule that results in a STOP action for every critical vulnerability.
Example rule set configuration in Anchore Enterprise
Gate: vulnerabilities
Trigger: package
Required Parameters: package type = “all”
Optional Parameters: severity comparison = “=”, severity = “critical”
Recommendations (optional): “Remediation is required for critical vulnerabilities.”
Action: STOP
Scenario 2
Goal: Create a rule that results in a STOP action for every vulnerability that is a part of CISA’s KEV list.
Example rule set configuration in Anchore Enterprise
Gate: vulnerabilities
Trigger: kev list
Recommendations (optional): “This vulnerability is part of CISA’s Known Exploited Vulnerability (KEV) catalogue. Remediation is required.”
Action: STOP
Scenario 3
Goal: Create a rule that results in a WARN action for every critical vulnerability with a fix that will not be addressed by a vendor.
Example rule set configuration in Anchore Enterprise
Gate: vulnerabilities
Trigger: package
Required Parameters: package type = “all”
Optional Parameters: severity comparison = “=”, severity = “critical”, vendor only = “false”
Recommendations (optional): “Even though this is a critical vulnerability, the vendor indicates that a fix will not be addressed.”
Action: WARN
Reference: vulnerabilities
| Trigger Name | Description | Parameter | Description | Example |
|---|
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | package_type | Only trigger for specific package type. | all |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | severity_comparison | The type of comparison to perform for severity evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | severity | Severity to compare against. | high |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | cvss_v3_base_score_comparison | The type of comparison to perform for CVSS v3 base score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | cvss_v3_base_score | CVSS v3 base score to compare against. | None |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | cvss_v3_exploitability_score_comparison | The type of comparison to perform for CVSS v3 exploitability sub score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | cvss_v3_exploitability_score | CVSS v3 exploitability sub score to compare against. | None |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | cvss_v3_impact_score_comparison | The type of comparison to perform for CVSS v3 impact sub score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | cvss_v3_impact_score | CVSS v3 impact sub score to compare against. | None |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | fix_available | If present, the fix availability for the vulnerability record must match the value of this parameter. | true |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_only | If True, an available fix for this CVE must not be explicitly marked as wont be addressed by the vendor | true |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | max_days_since_creation | A grace period, in days, for a vulnerability match to be present after which the vulnerability is a policy violation. Uses the date the match was first found for the given image. | 7 |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | max_days_since_fix | If provided (only evaluated when fix_available option is also set to true), the fix first observed time must be older than the days provided, to trigger. | 30 |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_cvss_v3_base_score_comparison | The type of comparison to perform for vendor specified CVSS v3 base score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_cvss_v3_base_score | Vendor CVSS v3 base score to compare against. | None |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_cvss_v3_exploitability_score_comparison | The type of comparison to perform for vendor specified CVSS v3 exploitability sub score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_cvss_v3_exploitability_score | Vendor CVSS v3 exploitability sub score to compare against. | None |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_cvss_v3_impact_score_comparison | The type of comparison to perform for vendor specified CVSS v3 impact sub score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | vendor_cvss_v3_impact_score | Vendor CVSS v3 impact sub score to compare against. | None |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | package_path_exclude | The regex to evaluate against the package path to exclude vulnerabilities | .test.jar |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | inherited_from_base | If true, only show vulns inherited from the base, if false than only show vulns not inherited from the base. Don’t specify to include vulns from the base image and the current image. See Base Images for more details. | True |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | epss score | The EPSS score to compare against. | 0.25 |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | epss_score_comparison | The type of comparison to perform for EPSS base score evaluation. | > |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | epss percentile | The EPSS percentile to compare against. | 87 |
| package | Triggers if a found vulnerability in an image meets the comparison criteria. | epss percentile comparison | The type of comparison to perform for EPSS percentile evaluation. | > |
| denylist | Triggers if any of a list of specified vulnerabilities has been detected in the image. | vulnerability_ids | List of vulnerability IDs, will cause the trigger to fire if any are detected. | CVE-2019-1234 |
| denylist | Triggers if any of a list of specified vulnerabilities has been detected in the image. | vendor_only | If set to True, discard matches against this vulnerability if vendor has marked as will not fix in the vulnerability record. | True |
| stale_feed_data | Triggers if the CVE data is older than the window specified by the parameter MAXAGE (unit is number of days). | max_days_since_sync | Fire the trigger if the last sync was more than this number of days ago. | 10 |
| vulnerability_data_unavailable | Triggers if vulnerability data is unavailable for the image’s distro packages such as rpms or dpkg. Non-OS packages like npms and java are not considered in this evaluation | None | None | None |
| kev_list_data_missing | Triggers if the KEV list data has not been synced. | None | None | None |
| kev_list | Triggers if any vulnerabilities are on the KEV list. | None | None | None |
