Permission Types

Access control in SaaS (Software-as-a-Service) applications is crucial for ensuring security, compliance, and user management. Below is a comprehensive guide covering different access control models, best practices, and implementation strategies.
Author

Benedict Thekkel

1️⃣ What is an Access Control System?

A permission and access control system determines who can access what in a SaaS application. It defines user roles, permissions, and restrictions to ensure data security and compliance.

🔹 Key Components:
- Authentication (AuthN): Verifies identity (e.g., email, password, MFA).
- Authorization (AuthZ): Determines what a user can do.
- Roles & Permissions: Assign different access levels to users.

2️⃣ Types of Access Control Models

1. Role-Based Access Control (RBAC) 🔑

  • Users are assigned roles (e.g., Admin, Manager, User).
  • Roles have predefined permissions (e.g., “Admin can delete users”).
  • Easy to manage but not flexible for fine-grained control.

✅ Best for: SaaS apps with structured user roles (e.g., CRM, ERP, HR software).

Example:
| Role | Can Read? | Can Write? | Can Delete? |
|———-|———-|————|————-|
| Admin | ✅ | ✅ | ✅ |
| Manager | ✅ | ✅ | ❌ |
| User | ✅ | ❌ | ❌ |

2. Attribute-Based Access Control (ABAC) 🏷️

  • Access is granted based on user attributes (e.g., location, department, subscription level).
  • Dynamic rules define access (e.g., “Only users from the Finance department can access invoices”).
  • More flexible but complex to manage.

✅ Best for: Large enterprises or multi-tenant SaaS platforms.

Example Rule:

if user.department == "Finance" and user.location == "USA":
    allow_access("Invoices")

3. Policy-Based Access Control (PBAC) 📜

  • Uses policies to define access dynamically.
  • Based on RBAC + ABAC with conditions (e.g., “Managers can edit reports if they belong to the same region”).
  • Often implemented using JSON-based policies (e.g., AWS IAM).

✅ Best for: Scalable SaaS apps with complex business rules.

Example Policy (JSON Format - AWS IAM Style):

{
    "Effect": "Allow",
    "Action": "reports:edit",
    "Condition": {
        "StringEquals": {
            "user.role": "Manager",
            "user.region": "report.region"
        }
    }
}

4. Discretionary Access Control (DAC) 🔐

  • Each resource owner decides who can access their resources.
  • Users can share files, documents, or projects with specific people.

✅ Best for: Collaboration tools (e.g., Google Drive, Notion, Dropbox).

Example:
A user shares a document with another user who wasn’t originally assigned a role.

5. Mandatory Access Control (MAC) 🔒

  • Strict, military-grade security where users cannot modify permissions.
  • Used in government, banking, and highly regulated industries.

✅ Best for: High-security SaaS apps needing strict data protection.

3️⃣ Key Features of a Permission System

🔹 Granular Permissions: Fine-tuned control over actions like read, write, update, delete.
🔹 Hierarchical Roles: Admins > Managers > Users.
🔹 Multi-Tenancy Support: Separate permissions for different organizations (e.g., SaaS B2B).
🔹 Audit Logs & Monitoring: Track access and changes for compliance.
🔹 Delegated Access & Sharing: Users can grant temporary access to others.
🔹 Least Privilege Principle: Users get only the access they need.

4️⃣ Best Practices for SaaS Access Control

✅ Use a Centralized Identity Provider (IdP)
🔹 Implement OAuth 2.0, OpenID Connect (OIDC), or SAML for authentication.
🔹 Use services like Okta, Auth0, AWS Cognito, Azure AD.

✅ Implement Multi-Factor Authentication (MFA)
🔹 Enforce MFA for sensitive operations like billing changes or admin actions.

✅ Use Role-Based Defaults & Custom Roles
🔹 Offer predefined roles (Admin, User, Guest) but allow custom permissions.

✅ Design for Scalability
🔹 Support thousands of users with hierarchical roles and group-based policies.

✅ Audit & Log Everything
🔹 Log failed login attempts, permission changes, API access for security audits.

✅ Follow the Principle of Least Privilege (PoLP)
🔹 Default users to minimal access and require explicit elevation.

✅ Use Token-Based Authorization (JWT, OAuth 2.0)
🔹 Secure API requests with JWT or OAuth Bearer tokens.

5️⃣ SaaS Access Control Implementation (Example in Django)

Here’s a Django example of RBAC with Django’s built-in permissions system:

from django.contrib.auth.models import User, Group, Permission
from django.contrib.contenttypes.models import ContentType
from myapp.models import Document

# Create a new role (Group)
manager_group = Group.objects.create(name="Manager")

# Define permissions
content_type = ContentType.objects.get_for_model(Document)
perm = Permission.objects.create(
    codename='can_edit_documents',
    name='Can Edit Documents',
    content_type=content_type,
)

# Assign permission to the role (group)
manager_group.permissions.add(perm)

# Assign role to a user
user = User.objects.get(username="john_doe")
user.groups.add(manager_group)

# Check if user has permission
if user.has_perm("myapp.can_edit_documents"):
    print("User can edit documents!")

✅ Django, Flask, and Node.js all support built-in role-based authentication.
✅ For larger applications, consider AWS IAM, Okta, or Auth0.

7️⃣ Access Control for Multi-Tenant SaaS

If your SaaS serves multiple organizations, consider: 1. Row-Level Security (RLS)
- Restrict database access per tenant ID. 2. Per-Organization Roles
- Each organization has its own admin and users. 3. Tenant-Based API Authorization
- APIs enforce access based on tenant ownership.

🔹 Example:

SELECT * FROM documents WHERE tenant_id = CURRENT_TENANT_ID;

🔹 Summary Table: SaaS Access Control Models

Model Flexibility Security Best For
RBAC Medium High SaaS with predefined roles
ABAC High High Dynamic access control
PBAC Very High Very High Complex SaaS policies
DAC Medium Low User-driven access (collaboration tools)
MAC Low Very High Government & banking

🚀 Final Thoughts

🔹 For simple SaaS apps → Use RBAC (with predefined roles).
🔹 For dynamic, scalable access → Use ABAC or PBAC.
🔹 For multi-tenant SaaS → Implement row-level security & per-tenant roles.
🔹 For enterprise security → Use OAuth, SAML, and centralized IdPs.

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