What Access Control Policy Do You Need?

Why Developers Need Real Access Control Policies (Not Just Theory)

If you’re pushing code, maintaining pipelines, or managing artifact registries, you need more than theory. Weak or undefined access control policies invite repo tampering, CI/CD abuse, and credential leaks. DevSecOps demands real enforcement, not just buried permission settings.

To effectively manage access control policies across code repositories, CI/CD pipelines, and artifact registries, many teams rely on automated enforcement tools like Xygeni. By continuously monitoring roles, permissions, and policy adherence, Xygeni helps prevent permission drift, unauthorized access, and manual overrides, turning mandatory access control theory into action.

Access control directly locks down your source code, secures your builds, and protects your production pipeline. If developers bypass controls or service accounts have broad permissions, you’re opening the door to security breaches. That’s why understanding mandatory access control, MAC access control, and other models is critical.

Types of Access Control Policies Developers Should Know

Access control policies fall into three main categories, each fits differently in CI/CD workflows. Here’s a quick side-by-side breakdown to clarify:

Model	Who Controls Access?	Typical Use in CI/CD	Risk Level
DAC (Discretionary Access Control)	Resource owner (developer, admin)	Manual sharing of repo or registry access	High (human error)
RBAC (Role-Based Access Control)	System assigns permissions by role	GitHub branch protection, CI job access based on user roles	Medium (misconfigured roles)
MAC (Mandatory Access Control)	Enforced by system policy	Enforces who can publish artifacts or deploy code	Low (policy overrides user intent)

Clarifying MAC vs. RBAC in CI/CD Context

It’s easy to confuse role-based access control (RBAC) with mandatory access control (mac access control), especially in CI/CD environments. While CI/CD platforms like GitHub and GitLab use RBAC to manage roles and permissions (e.g., who can merge or deploy), this is still fundamentally role-based, not true MAC access control.

RBAC lets you assign permissions based on roles (developer, maintainer, etc.), but those permissions are still user-controlled and modifiable. Misconfigurations or permission creep are common risks.

Mandatory access control (MAC access control), by contrast, is enforced at the system or infrastructure level. Users, including admins, cannot override it. Think of Mac access control as policies embedded into the platform: IAM policies in cloud providers (e.g., AWS IAM, GCP IAM), or OS-level enforcement tools like SELinux or AppArmor. In these cases, access is granted only when predefined, non-bypassable rules are met.

In CI/CD, many tools simulate MAC access control behavior through tightly scoped IAM roles or resource-specific permissions, but this isn’t full mandatory access control. Real mandatory access control enforcement requires controls below the application layer, at the OS, network, or cloud infrastructure level, where access is governed by immutable access control policies, not human configuration.

Role-Based Access Control (RBAC)

RBAC maps permissions to defined roles like “developer,” “maintainer,” or “release manager.” It simplifies management in tools like GitHub and GitLab. Instead of configuring user-by-user, assign them to a role and let the system enforce the rules.

Example: GitHub CODEOWNERS file

# CODEOWNERS
/docs/ @doc-team
/scripts/ @devops-team
/main.py @maintainers

This ensures that only the assigned roles can approve changes in critical directories.

GitLab role settings: Configure project access in Settings > Members:

Developer: Can push to feature branches.
Maintainer: Can merge into protected branches.
Guest: Read-only access.

GitHub Actions Workflow RBAC example:

yaml
# .github/workflows/deploy.yml
name: Deploy to Production
on:
  push:
    branches:
      - main
jobs:
  deploy:
    if: github.actor == 'release-manager'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v2
      - name: Deploy
        run: ./scripts/deploy.sh

Mandatory Access Control (MAC)

Mandatory access control (MAC access control) enforces strict, system-level rules that users and admins cannot override. Use Mac access control to tightly control who can read, write, or execute critical resources.

Example: Google Artifact Registry Policy (Simplified YAML)

yaml
bindings:
  - role: roles/artifactregistry.writer
    members:
      - serviceAccount:ci-deployer@project.iam.gserviceaccount.com

This policy grants write permission only to the ci-deployer service account, ensuring only CI jobs with this identity can push artifacts.

Example: Amazon ECR Policy (Simplified YAML)

yaml
Version: "2008-10-17"
Statement:
  - Effect: Deny
    Principal: "*"
    Action: ecr:PutImage
    Resource: arn:aws:ecr:region:account-id:repository/my-app
    Condition:
      StringNotEquals:
        aws:userid: ci-service-account

This policy denies any PutImage action on the ECR repository unless performed by the ci-service-account. It restricts image uploads strictly to this service account.

Risks of Manual Override and How MAC Prevents Them

One of the biggest risks with RBAC and DAC models is the potential for intentional or accidental manual overrides. For example, an admin or developer might directly upload artifacts to a protected registry or grant excessive permissions outside defined access control policies. These actions can introduce vulnerabilities or cause compliance gaps.

Mandatory access control (MAC access control) prevents such overrides by enforcing system-level policies that no user, even admins, can bypass. Access decisions are governed by immutable rules embedded into the infrastructure (like cloud IAM policies or OS-level security modules). This means:

An admin cannot manually upload artifacts to a registry if the Mac access control policy denies them.
Users cannot escalate privileges or alter permissions outside the defined access control policies.
Automated CI/CD pipelines run strictly within their assigned permissions, preventing scope creep.

By eliminating manual overrides, mandatory access control ensures a stronger, more reliable security posture than RBAC or DAC alone.

2.4 Discretionary Access Control (DAC)

DAC lets resource owners manually assign permissions. It’s flexible but risky. One wrong share can compromise a repo. DAC works like: “You own it, you decide who gets in.”

Example: a dev invites an external collaborator and gives them write access to the repo. The collaborator pushes insecure code directly to the dev branch.

In CI/CD, DAC might look like a developer manually granting production deploy access to a temporary team member via console, outside any defined access control policy.

How to Choose an Access Control Policy That Works in Real Pipelines

Access Control in Git

Leverage RBAC to manage contributor, maintainer, and release roles. Lock merge rights to protected branches. Require signed commits and limit who can bypass protections.

Example: GitHub Branch Protection Rules

Require pull request reviews before merging.
Dismiss stale pull request approvals when new commits are pushed.
Require signed commits.
Skip DAC for production-critical repos. Don’t hand out write access casually.

Pipeline Enforcement

Put mandatory access control in place for pipelines. A solid Mac access control model limits CI jobs to only the permissions they need.

Separate secrets by environment.
Use unique tokens per environment.
Prevent manual runs from affecting production.

Example: a CI job reuses a deploy token across staging and prod, accidentally pushing test code to live.

Add Mac access control rules to control token scope:

yaml
env:
  DEPLOY_TOKEN: ${{ secrets.DEPLOY_TOKEN_PROD }}
if: github.ref == 'refs/heads/main' && github.actor == 'release-manager'

Secrets Scoping Example: Environment-Specific Token Usage

Properly scoping secrets by environment is critical to prevent accidental or malicious cross-environment access. For example, a deployment token for the development environment should never be usable to deploy to production.

Here’s how access control policy-based controls isolate secret usage in GitHub Actions:

yaml
env:
  DEPLOY_TOKEN_DEV: ${{ secrets.DEPLOY_TOKEN_DEV }}
  DEPLOY_TOKEN_PROD: ${{ secrets.DEPLOY_TOKEN_PROD }}

jobs:
  deploy-dev:
    if: github.ref == 'refs/heads/dev' && github.actor == 'developer'
    runs-on: ubuntu-latest
    steps:
      - name: Deploy to Dev
        run: ./deploy.sh
        env:
          TOKEN: ${{ env.DEPLOY_TOKEN_DEV }}

  deploy-prod:
    if: github.ref == 'refs/heads/main' && github.actor == 'release-manager'
    runs-on: ubuntu-latest
    steps:
      - name: Deploy to Prod
        run: ./deploy.sh
        env:
          TOKEN: ${{ env.DEPLOY_TOKEN_PROD }}

This enforces that:

Only the developer role can trigger deployments using the dev token on the dev branch.
Only the release-manager role can deploy to production using the prod token on the main branch.

Such scoped secret usage reduces the risk of token leaks escalating across environments and enforces least privilege in CI/CD pipelines following strong access control policies.

Artifact Access Controls

Lock down artifact registries using mandatory access control. CI/CD systems should handle publishing, not individual developers.

Use RBAC to define which teams pull from specific registries. Developers may only need read access to production packages.

json
{
  "rules": [
    {
      "action": "read",
      "resource": "npm-package:internal/*",
      "allowed_roles": ["developer", "qa"]
    },
    {
      "action": "write",
      "resource": "npm-package:internal/*",
      "allowed_principals": ["ci-pipeline"]
    }
  ]
}

Common Access Control Failures in Dev Workflows

Over-Permissive Repo Access

Problem: Granting too many users write/admin access to repos.
How It Happens: Team members get promoted or added without permissions being reviewed. Roles become bloated.
Attacker Exploit: Attackers target these accounts using stolen credentials or social engineering. Once inside, they can inject malicious code, backdoors, or remove history to hide traces.

Shared Permissions Between Dev and Prod

Problem: Letting dev and prod pipelines share permissions.
How It Happens: Teams reuse the same deploy token or CI service account across environments.
Attacker Exploit: A dev environment breach gives attackers production access. Mandatory access control can prevent this by binding permissions to specific environments.

Manual Artifact Uploads

Problem: Allowing manual artifact uploads to production registries.
How It Happens: Developers bypass pipelines for quick fixes or hot patches.
Attacker Exploit: Compromised developer machines can upload malware directly to artifact storage, bypassing all CI/CD security checks.

Registry Policy Abuse Risk: Manually publishing artifacts creates a critical attack surface in the software supply chain. Attackers exploiting lax access control policies can insert malicious code into trusted packages or container images, leading to widespread downstream compromise. Recent software supply chain incidents have shown how unregulated artifact uploads can rapidly escalate into major security breaches, affecting countless users and systems.

Example: an intern with full npm registry access publishes an unstable version by mistake. If an attacker had compromised that intern’s machine, they could have published malware instead.

Practical Steps to Enforce Strong Access Controls

Map roles to exact permissions, ditch one-role-fits-all setups
Automate access control policy checks in your CI/CD pipelines
Lock down registries with mandatory access control
Continuously log and monitor access to critical systems
Treat access control policies like code. Every misstep can be exploited

Xygeni’s Role: Enforcing and Monitoring Access Policies in DevOps Workflows

Xygeni helps you turn mandatory access control from theory into action by solving real, day-to-day access control policy enforcement challenges in DevSecOps pipelines.

Solving Over-Permissioned Git Access: Xygeni continuously monitors Git repositories for RBAC violations such as unreviewed role assignments or missing branch protections. It alerts when access control policies drift from defined rules and enforces corrective actions to avoid accidental merges or malicious PRs.
Locking Down CI/CD Pipelines: CI jobs sometimes run with broader scopes than intended. Xygeni detects when CI/CD jobs request or operate beyond their assigned roles, identifying scope creep and privilege misuse in real-time. This helps enforce MAC access control principles inside pipelines by tying access strictly to the job’s identity and purpose.
Enforcing Artifact Publishing Controls: If developers are still manually uploading artifacts or images, Xygeni puts a stop to that. It applies registry-level mandatory access control so that only verified pipeline identities can publish artifacts. No more human uploads to production registries.
Monitoring Access and Flagging Anomalies: With Xygeni, you get visibility into who accessed what, when, and how. It continuously tracks secrets usage, repository access, and registry interactions to detect unusual behavior, flag misconfigurations, and help with post-incident analysis.

Bottom line: Xygeni brings automation and enforcement to access control policy so your DevOps environment stays secure without slowing you down.

What Access Control Policy Do You Need? Let’s Break It Down

Table of Contents

Must-Read posts

Latest posts of interest