594 lines
15 KiB
Markdown
594 lines
15 KiB
Markdown
---
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name: django-security
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description: Django security best practices, authentication, authorization, CSRF protection, SQL injection prevention, XSS prevention, and secure deployment configurations.
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origin: ECC
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---
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# Django Security Best Practices
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Comprehensive security guidelines for Django applications to protect against common vulnerabilities.
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## When to Activate
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- Setting up Django authentication and authorization
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- Implementing user permissions and roles
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- Configuring production security settings
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- Reviewing Django application for security issues
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- Deploying Django applications to production
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## Core Security Settings
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### Production Settings Configuration
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```python
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# settings/production.py
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import os
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DEBUG = False # CRITICAL: Never use True in production
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ALLOWED_HOSTS = os.environ.get('ALLOWED_HOSTS', '').split(',')
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# Security headers
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SECURE_SSL_REDIRECT = True
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SESSION_COOKIE_SECURE = True
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CSRF_COOKIE_SECURE = True
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SECURE_HSTS_SECONDS = 31536000 # 1 year
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SECURE_HSTS_INCLUDE_SUBDOMAINS = True
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SECURE_HSTS_PRELOAD = True
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SECURE_CONTENT_TYPE_NOSNIFF = True
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SECURE_BROWSER_XSS_FILTER = True
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X_FRAME_OPTIONS = 'DENY'
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# HTTPS and Cookies
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SESSION_COOKIE_HTTPONLY = True
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CSRF_COOKIE_HTTPONLY = True
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SESSION_COOKIE_SAMESITE = 'Lax'
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CSRF_COOKIE_SAMESITE = 'Lax'
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# Secret key (must be set via environment variable)
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SECRET_KEY = os.environ.get('DJANGO_SECRET_KEY')
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if not SECRET_KEY:
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raise ImproperlyConfigured('DJANGO_SECRET_KEY environment variable is required')
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# Password validation
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AUTH_PASSWORD_VALIDATORS = [
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{
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'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
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},
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{
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'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
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'OPTIONS': {
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'min_length': 12,
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}
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},
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{
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'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
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},
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{
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'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
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},
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]
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```
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## Authentication
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### Custom User Model
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```python
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# apps/users/models.py
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from django.contrib.auth.models import AbstractUser
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from django.db import models
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class User(AbstractUser):
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"""Custom user model for better security."""
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email = models.EmailField(unique=True)
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phone = models.CharField(max_length=20, blank=True)
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USERNAME_FIELD = 'email' # Use email as username
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REQUIRED_FIELDS = ['username']
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class Meta:
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db_table = 'users'
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verbose_name = 'User'
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verbose_name_plural = 'Users'
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def __str__(self):
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return self.email
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# settings/base.py
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AUTH_USER_MODEL = 'users.User'
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```
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### Password Hashing
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```python
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# Django uses PBKDF2 by default. For stronger security:
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PASSWORD_HASHERS = [
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'django.contrib.auth.hashers.Argon2PasswordHasher',
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'django.contrib.auth.hashers.PBKDF2PasswordHasher',
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'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
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'django.contrib.auth.hashers.BCryptSHA256PasswordHasher',
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]
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```
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### Session Management
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```python
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# Session configuration
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SESSION_ENGINE = 'django.contrib.sessions.backends.cache' # Or 'db'
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SESSION_CACHE_ALIAS = 'default'
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SESSION_COOKIE_AGE = 3600 * 24 * 7 # 1 week
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SESSION_SAVE_EVERY_REQUEST = False
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SESSION_EXPIRE_AT_BROWSER_CLOSE = False # Better UX, but less secure
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```
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## Authorization
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### Permissions
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```python
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# models.py
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from django.db import models
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from django.contrib.auth.models import Permission
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class Post(models.Model):
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title = models.CharField(max_length=200)
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content = models.TextField()
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author = models.ForeignKey(User, on_delete=models.CASCADE)
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class Meta:
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permissions = [
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('can_publish', 'Can publish posts'),
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('can_edit_others', 'Can edit posts of others'),
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]
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def user_can_edit(self, user):
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"""Check if user can edit this post."""
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return self.author == user or user.has_perm('app.can_edit_others')
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# views.py
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from django.contrib.auth.mixins import LoginRequiredMixin, PermissionRequiredMixin
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from django.views.generic import UpdateView
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class PostUpdateView(LoginRequiredMixin, PermissionRequiredMixin, UpdateView):
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model = Post
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permission_required = 'app.can_edit_others'
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raise_exception = True # Return 403 instead of redirect
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def get_queryset(self):
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"""Only allow users to edit their own posts."""
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return Post.objects.filter(author=self.request.user)
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```
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### Custom Permissions
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```python
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# permissions.py
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from rest_framework import permissions
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class IsOwnerOrReadOnly(permissions.BasePermission):
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"""Allow only owners to edit objects."""
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def has_object_permission(self, request, view, obj):
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# Read permissions allowed for any request
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if request.method in permissions.SAFE_METHODS:
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return True
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# Write permissions only for owner
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return obj.author == request.user
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class IsAdminOrReadOnly(permissions.BasePermission):
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"""Allow admins to do anything, others read-only."""
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def has_permission(self, request, view):
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if request.method in permissions.SAFE_METHODS:
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return True
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return request.user and request.user.is_staff
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class IsVerifiedUser(permissions.BasePermission):
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"""Allow only verified users."""
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def has_permission(self, request, view):
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return request.user and request.user.is_authenticated and request.user.is_verified
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```
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### Role-Based Access Control (RBAC)
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```python
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# models.py
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from django.contrib.auth.models import AbstractUser, Group
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class User(AbstractUser):
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ROLE_CHOICES = [
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('admin', 'Administrator'),
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('moderator', 'Moderator'),
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('user', 'Regular User'),
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]
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role = models.CharField(max_length=20, choices=ROLE_CHOICES, default='user')
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def is_admin(self):
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return self.role == 'admin' or self.is_superuser
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def is_moderator(self):
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return self.role in ['admin', 'moderator']
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# Mixins
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class AdminRequiredMixin:
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"""Mixin to require admin role."""
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def dispatch(self, request, *args, **kwargs):
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if not request.user.is_authenticated or not request.user.is_admin():
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from django.core.exceptions import PermissionDenied
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raise PermissionDenied
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return super().dispatch(request, *args, **kwargs)
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```
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## SQL Injection Prevention
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### Django ORM Protection
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```python
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# GOOD: Django ORM automatically escapes parameters
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def get_user(username):
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return User.objects.get(username=username) # Safe
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# GOOD: Using parameters with raw()
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def search_users(query):
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return User.objects.raw('SELECT * FROM users WHERE username = %s', [query])
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# BAD: Never directly interpolate user input
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def get_user_bad(username):
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return User.objects.raw(f'SELECT * FROM users WHERE username = {username}') # VULNERABLE!
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# GOOD: Using filter with proper escaping
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def get_users_by_email(email):
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return User.objects.filter(email__iexact=email) # Safe
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# GOOD: Using Q objects for complex queries
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from django.db.models import Q
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def search_users_complex(query):
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return User.objects.filter(
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Q(username__icontains=query) |
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Q(email__icontains=query)
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) # Safe
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```
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### Extra Security with raw()
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```python
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# If you must use raw SQL, always use parameters
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User.objects.raw(
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'SELECT * FROM users WHERE email = %s AND status = %s',
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[user_input_email, status]
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)
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```
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## XSS Prevention
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### Template Escaping
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```django
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{# Django auto-escapes variables by default - SAFE #}
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{{ user_input }} {# Escaped HTML #}
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{# Explicitly mark safe only for trusted content #}
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{{ trusted_html|safe }} {# Not escaped #}
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{# Use template filters for safe HTML #}
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{{ user_input|escape }} {# Same as default #}
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{{ user_input|striptags }} {# Remove all HTML tags #}
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{# JavaScript escaping #}
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<script>
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var username = {{ username|escapejs }};
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</script>
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```
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### Safe String Handling
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```python
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from django.utils.safestring import mark_safe
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from django.utils.html import escape
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# BAD: Never mark user input as safe without escaping
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def render_bad(user_input):
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return mark_safe(user_input) # VULNERABLE!
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# GOOD: Escape first, then mark safe
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def render_good(user_input):
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return mark_safe(escape(user_input))
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# GOOD: Use format_html for HTML with variables
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from django.utils.html import format_html
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def greet_user(username):
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return format_html('<span class="user">{}</span>', escape(username))
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```
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### HTTP Headers
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```python
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# settings.py
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SECURE_CONTENT_TYPE_NOSNIFF = True # Prevent MIME sniffing
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SECURE_BROWSER_XSS_FILTER = True # Enable XSS filter
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X_FRAME_OPTIONS = 'DENY' # Prevent clickjacking
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# Custom middleware
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from django.conf import settings
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class SecurityHeaderMiddleware:
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def __init__(self, get_response):
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self.get_response = get_response
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def __call__(self, request):
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response = self.get_response(request)
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response['X-Content-Type-Options'] = 'nosniff'
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response['X-Frame-Options'] = 'DENY'
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response['X-XSS-Protection'] = '1; mode=block'
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response['Content-Security-Policy'] = "default-src 'self'"
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return response
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```
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## CSRF Protection
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### Default CSRF Protection
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```python
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# settings.py - CSRF is enabled by default
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CSRF_COOKIE_SECURE = True # Only send over HTTPS
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CSRF_COOKIE_HTTPONLY = True # Prevent JavaScript access
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CSRF_COOKIE_SAMESITE = 'Lax' # Prevent CSRF in some cases
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CSRF_TRUSTED_ORIGINS = ['https://example.com'] # Trusted domains
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# Template usage
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<form method="post">
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{% csrf_token %}
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{{ form.as_p }}
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<button type="submit">Submit</button>
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</form>
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# AJAX requests
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function getCookie(name) {
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let cookieValue = null;
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if (document.cookie && document.cookie !== '') {
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const cookies = document.cookie.split(';');
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for (let i = 0; i < cookies.length; i++) {
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const cookie = cookies[i].trim();
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if (cookie.substring(0, name.length + 1) === (name + '=')) {
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cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
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break;
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}
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}
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}
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return cookieValue;
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}
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fetch('/api/endpoint/', {
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method: 'POST',
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headers: {
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'X-CSRFToken': getCookie('csrftoken'),
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'Content-Type': 'application/json',
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},
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body: JSON.stringify(data)
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});
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```
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### Exempting Views (Use Carefully)
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```python
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from django.views.decorators.csrf import csrf_exempt
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@csrf_exempt # Only use when absolutely necessary!
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def webhook_view(request):
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# Webhook from external service
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pass
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```
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## File Upload Security
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### File Validation
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```python
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import os
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from django.core.exceptions import ValidationError
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def validate_file_extension(value):
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"""Validate file extension."""
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ext = os.path.splitext(value.name)[1]
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valid_extensions = ['.jpg', '.jpeg', '.png', '.gif', '.pdf']
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if not ext.lower() in valid_extensions:
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raise ValidationError('Unsupported file extension.')
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def validate_file_size(value):
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"""Validate file size (max 5MB)."""
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filesize = value.size
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if filesize > 5 * 1024 * 1024:
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raise ValidationError('File too large. Max size is 5MB.')
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# models.py
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class Document(models.Model):
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file = models.FileField(
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upload_to='documents/',
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validators=[validate_file_extension, validate_file_size]
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)
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```
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### Secure File Storage
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```python
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# settings.py
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MEDIA_ROOT = '/var/www/media/'
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MEDIA_URL = '/media/'
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# Use a separate domain for media in production
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MEDIA_DOMAIN = 'https://media.example.com'
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# Don't serve user uploads directly
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# Use whitenoise or a CDN for static files
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# Use a separate server or S3 for media files
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```
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## API Security
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### Rate Limiting
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```python
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# settings.py
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REST_FRAMEWORK = {
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'DEFAULT_THROTTLE_CLASSES': [
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'rest_framework.throttling.AnonRateThrottle',
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'rest_framework.throttling.UserRateThrottle'
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],
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'DEFAULT_THROTTLE_RATES': {
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'anon': '100/day',
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'user': '1000/day',
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'upload': '10/hour',
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}
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}
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# Custom throttle
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from rest_framework.throttling import UserRateThrottle
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class BurstRateThrottle(UserRateThrottle):
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scope = 'burst'
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rate = '60/min'
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class SustainedRateThrottle(UserRateThrottle):
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scope = 'sustained'
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rate = '1000/day'
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```
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### Authentication for APIs
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```python
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# settings.py
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REST_FRAMEWORK = {
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'DEFAULT_AUTHENTICATION_CLASSES': [
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'rest_framework.authentication.TokenAuthentication',
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'rest_framework.authentication.SessionAuthentication',
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'rest_framework_simplejwt.authentication.JWTAuthentication',
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],
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'DEFAULT_PERMISSION_CLASSES': [
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'rest_framework.permissions.IsAuthenticated',
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],
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}
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# views.py
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from rest_framework.decorators import api_view, permission_classes
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from rest_framework.permissions import IsAuthenticated
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@api_view(['GET', 'POST'])
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@permission_classes([IsAuthenticated])
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def protected_view(request):
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return Response({'message': 'You are authenticated'})
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```
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## Security Headers
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### Content Security Policy
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```python
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# settings.py
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CSP_DEFAULT_SRC = "'self'"
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CSP_SCRIPT_SRC = "'self' https://cdn.example.com"
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CSP_STYLE_SRC = "'self' 'unsafe-inline'"
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CSP_IMG_SRC = "'self' data: https:"
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CSP_CONNECT_SRC = "'self' https://api.example.com"
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# Middleware
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class CSPMiddleware:
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def __init__(self, get_response):
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self.get_response = get_response
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def __call__(self, request):
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response = self.get_response(request)
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response['Content-Security-Policy'] = (
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f"default-src {CSP_DEFAULT_SRC}; "
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f"script-src {CSP_SCRIPT_SRC}; "
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f"style-src {CSP_STYLE_SRC}; "
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f"img-src {CSP_IMG_SRC}; "
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f"connect-src {CSP_CONNECT_SRC}"
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)
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return response
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```
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## Environment Variables
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### Managing Secrets
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```python
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# Use python-decouple or django-environ
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import environ
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env = environ.Env(
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# set casting, default value
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DEBUG=(bool, False)
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)
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# reading .env file
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environ.Env.read_env()
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SECRET_KEY = env('DJANGO_SECRET_KEY')
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DATABASE_URL = env('DATABASE_URL')
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ALLOWED_HOSTS = env.list('ALLOWED_HOSTS')
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# .env file (never commit this)
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DEBUG=False
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SECRET_KEY=your-secret-key-here
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DATABASE_URL=postgresql://user:password@localhost:5432/dbname
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ALLOWED_HOSTS=example.com,www.example.com
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```
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## Logging Security Events
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```python
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# settings.py
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LOGGING = {
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'version': 1,
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'disable_existing_loggers': False,
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'handlers': {
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'file': {
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'level': 'WARNING',
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'class': 'logging.FileHandler',
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'filename': '/var/log/django/security.log',
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},
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'console': {
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'level': 'INFO',
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'class': 'logging.StreamHandler',
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},
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},
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'loggers': {
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'django.security': {
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'handlers': ['file', 'console'],
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'level': 'WARNING',
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'propagate': True,
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},
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'django.request': {
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'handlers': ['file'],
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'level': 'ERROR',
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'propagate': False,
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},
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},
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}
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```
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## Quick Security Checklist
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| Check | Description |
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|-------|-------------|
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| `DEBUG = False` | Never run with DEBUG in production |
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| HTTPS only | Force SSL, secure cookies |
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| Strong secrets | Use environment variables for SECRET_KEY |
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| Password validation | Enable all password validators |
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| CSRF protection | Enabled by default, don't disable |
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| XSS prevention | Django auto-escapes, don't use `|safe` with user input |
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| SQL injection | Use ORM, never concatenate strings in queries |
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| File uploads | Validate file type and size |
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| Rate limiting | Throttle API endpoints |
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| Security headers | CSP, X-Frame-Options, HSTS |
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| Logging | Log security events |
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| Updates | Keep Django and dependencies updated |
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Remember: Security is a process, not a product. Regularly review and update your security practices.
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