Least privilege principle in GCP - Time & Space Complexity

Time Complexity: Least privilege principle

O(n x m)

Understanding Time Complexity

We want to understand how the time it takes to manage permissions grows as we add more users or resources in Google Cloud.

Specifically, how does applying the least privilege principle affect the number of permission checks and updates?

Scenario Under Consideration

Analyze the time complexity of assigning roles with least privilege to multiple users.

// Pseudocode for assigning least privilege roles
for user in users_list:
  for resource in resources_list:
    assign_minimum_role(user, resource)

This sequence assigns the minimum required role to each user for each resource they need access to.

Identify Repeating Operations

Identify the API calls, resource provisioning, data transfers that repeat.

• Primary operation: Assigning a role to a user for a resource (API call to update IAM policy)
• How many times: Once for each user-resource pair

How Execution Grows With Input

As the number of users or resources grows, the total assignments grow by multiplying these counts.

Input Size (n users x m resources)	Approx. API Calls/Operations
10 users x 10 resources	100
100 users x 100 resources	10,000
1000 users x 1000 resources	1,000,000

Pattern observation: The number of operations grows quickly as both users and resources increase, multiplying together.

Final Time Complexity

Time Complexity: O(n x m)

This means the time to assign least privilege roles grows proportionally to the number of users times the number of resources.

Common Mistake

[X] Wrong: "Assigning roles once per user is enough, regardless of how many resources they access."

[OK] Correct: Each resource may need a different role, so permissions must be assigned per user-resource pair, not just per user.

Interview Connect

Understanding how permission assignments scale helps you design secure and efficient access controls in cloud projects, a valuable skill in real-world cloud management.

Self-Check

"What if we grouped resources and assigned roles per group instead of per resource? How would the time complexity change?"

Practice

1. What does the least privilege principle mean in cloud security?

easy

A. Grant access based on seniority, not tasks

B. Give all users full access to all resources

C. Allow users to share passwords for easier access

D. Give users only the access they need to do their job

Solution

1. Step 1: Understand the principle meaning

   Least privilege means limiting access rights to the minimum necessary for tasks.

2. Step 2: Match the correct description

   Give users only the access they need to do their job correctly states giving only needed access, while others give too much or irrelevant access.

3. Final Answer:

   Give users only the access they need to do their job -> Option D

4. Quick Check:

   Least privilege = minimal necessary access [OK]

Hint: Least privilege means minimal access needed only [OK]

Common Mistakes:

• Thinking least privilege means full access
• Confusing least privilege with password sharing
• Assuming access depends on seniority

2. Which of the following is the correct way to assign a role following the least privilege principle in GCP IAM?

easy

A. Assign a predefined role that only allows necessary actions

B. Assign the 'Owner' role to all users for easy management

C. Assign the 'Editor' role to everyone to avoid permission issues

D. Assign no roles and let users request access when needed

Solution

1. Step 1: Review role assignment options

   Least privilege requires giving only necessary permissions, not broad ones like Owner or Editor.

2. Step 2: Identify the best practice

   Predefined roles with limited permissions fit least privilege best, so Assign a predefined role that only allows necessary actions is correct.

3. Final Answer:

   Assign a predefined role that only allows necessary actions -> Option A

4. Quick Check:

   Least privilege = specific predefined roles [OK]

Hint: Use predefined roles with minimal permissions [OK]

Common Mistakes:

• Assigning Owner or Editor roles broadly
• Not using predefined roles
• Giving no roles and causing delays

3. Consider this IAM policy snippet in GCP:

{
  "bindings": [
    {
      "role": "roles/storage.objectViewer",
      "members": ["user:[e-mail]"]
    }
  ]
}

What access does Alice have?

medium

A. Full control over storage buckets

B. Can view objects in storage buckets

C. Can edit and delete storage objects

D. No access to storage resources

Solution

1. Step 1: Identify the role assigned

   The role is 'roles/storage.objectViewer', which allows viewing objects only.

2. Step 2: Understand permissions of the role

   This role grants read-only access to storage objects, no editing or deleting.

3. Final Answer:

   Can view objects in storage buckets -> Option B

4. Quick Check:

   objectViewer = read-only access [OK]

Hint: Viewer roles allow read-only access [OK]

Common Mistakes:

• Confusing viewer with editor or owner roles
• Assuming viewer can delete or edit
• Ignoring the specific role name

4. You assigned the 'roles/editor' role to a service account, but it only needs to read data. What is the best fix to follow the least privilege principle?

medium

A. Keep the 'editor' role since it covers all needs

B. Remove the role and do not assign any role

C. Change the role to 'roles/viewer' or a more specific read-only role

D. Assign the 'owner' role for future flexibility

Solution

1. Step 1: Identify the problem with current role

   'roles/editor' grants broad permissions beyond reading, violating least privilege.

2. Step 2: Choose a role with minimal needed permissions

   Assigning 'roles/viewer' or a specific read-only role limits access appropriately.

3. Final Answer:

   Change the role to 'roles/viewer' or a more specific read-only role -> Option C

4. Quick Check:

   Least privilege = minimal needed permissions [OK]

Hint: Use read-only roles if only reading is needed [OK]

Common Mistakes:

• Keeping overly broad roles
• Removing roles entirely causing access failure
• Assigning owner role unnecessarily

5. You manage a GCP project with multiple teams. One team needs to deploy apps but should not access billing info. How do you apply the least privilege principle?

hard

A. Assign a custom role with deployment permissions but no billing access

B. Assign 'Project Owner' role to the team for full control

C. Assign the 'Project Editor' role to the team and 'Billing Admin' to a few users

D. Give the team billing account access to avoid deployment delays

Solution

1. Step 1: Understand team needs and restrictions

   The team needs deployment rights but must not access billing info.

2. Step 2: Choose role assignment following least privilege

   A custom role with only deployment permissions and no billing access fits best.

3. Final Answer:

   Assign a custom role with deployment permissions but no billing access -> Option A

4. Quick Check:

   Least privilege = custom roles for precise access [OK]

Hint: Use custom roles to separate duties precisely [OK]

Common Mistakes:

• Giving broad roles like Owner or Editor
• Granting billing access unnecessarily
• Ignoring custom roles for fine control