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File Access Control

File Access Control

Introduction

File Access Control is a mechanism that restricts and manages how users (subjects) can access files (objects) in a computer system. It ensures that only authorized users can perform specific operations like read, write, execute, or delete on files.

👉 It is a practical implementation of Access Control in operating systems and plays a major role in protecting data.

Meaning

File Access Control defines:

  • Who can access a file (user/process)
  • What actions they can perform
  • Under what conditions access is allowed

📌 It protects files from unauthorized access, modification, or deletion.

Objectives of File Access Control

  • Protect sensitive data
  • Prevent unauthorized access
  • Ensure data integrity
  • Maintain system security
  • Support accountability and auditing

Basic Components of File Access Control

1. Subjects

  • Users or processes requesting access
  • Example: Student, Admin

2. Objects

  • Files or directories
  • Example: result.txt, database file

3. Access Rights

  • Permissions like Read, Write, Execute

Types of File Access Rights

Access RightMeaning
Read (R)View file content
Write (W)Modify file
Execute (X)Run file/program
Delete (D)Remove file
Append (A)Add data

File Access Control Mechanisms

1. Access Control List (ACL)

Meaning

Each file has a list of users and their permissions.

Example

File: report.txt
User A → Read, Write  
User B → Read

2. File Permissions (Linux/Unix Model)

Categories

  • Owner
  • Group
  • Others

Permissions

  • r (read)
  • w (write)
  • x (execute)

Example

rwxr-xr--
Owner → Full access  
Group → Read & Execute  
Others → Read only

3. Capability List

Meaning

Each user has a list of files they can access and permissions.

4. Role-Based File Access Control (RBAC)

Meaning

Access to files is based on user roles.

Example

  • Student → Read access
  • Teacher → Read + Write
  • Admin → Full control

5. Mandatory Access Control (MAC)

Meaning

Files are assigned security labels.

Example

  • Confidential file → Only high-level users can access

Working of File Access Control

Step-by-Step

  1. User requests access to file
  2. System checks identity (authentication)
  3. System verifies permissions
  4. Access granted or denied
User → Request → Permission Check → Access Allowed / Denied

Advantages of File Access Control

  • Protects sensitive information
  • Prevents unauthorized modification
  • Enhances system security
  • Supports auditing and accountability
  • Helps in legal compliance

Limitations

  • Complex management in large systems
  • Misconfigured permissions can cause breaches
  • Insider threats still possible

File Access Control and CIA Triad

  • Confidentiality → Restricts file access
  • Integrity → Prevents unauthorized modification
  • Availability → Ensures authorized access

File Access Control in Cyber Law (India)

Under IT Act, 2000:

  • Section 43 → Unauthorized file access
  • Section 65 → Tampering with data

📌 Improper file protection can lead to legal penalties.

Real-Life Examples

Example 1: College System

  • Student → Read results
  • Teacher → Modify marks
  • Admin → Full control

Example 2: Office System

  • Employee → Read documents
  • Manager → Read + Write
  • IT Admin → Full access

Best Practices for File Access Control

  • Apply least privilege principle
  • Regularly review permissions
  • Use strong authentication
  • Enable logging and auditing
  • Avoid shared accounts

Conclusion

File Access Control is a critical security mechanism that ensures only authorized users can access and manipulate files. By properly assigning permissions and following security principles, organizations can protect their data, maintain integrity, and comply with legal standards.

📘 MCA Exam Tip

For 10–15 marks:

  • Definition
  • Components (subject, object, rights)
  • Mechanisms (ACL, permissions, RBAC)
  • Advantages + examples