60 lines
2.5 KiB
Python
60 lines
2.5 KiB
Python
import jwt
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from typing import List
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from fastapi import FastAPI, Depends, HTTPException, status
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from fastapi.security import OAuth2AuthorizationCodeBearer, SecurityScopes
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from jwt import PyJWKClient
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TENANT_ID = "your-tenant-id"
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API_CLIENT_ID = "your-backend-api-client-id" # The Application ID of the API itself
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JWKS_URL = f"https://login.microsoftonline.com/{TENANT_ID}/discovery/v2.0/keys"
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jwks_client = PyJWKClient(JWKS_URL)
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# Native security scheme enables the top-right "Authorize" button in Swagger UI
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oauth2_scheme = OAuth2AuthorizationCodeBearer(
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authorizationUrl=f"https://login.microsoftonline.com/{TENANT_ID}/oauth2/v2.0/authorize",
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tokenUrl=f"https://login.microsoftonline.com/{TENANT_ID}/oauth2/v2.0/token",
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)
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class EntraRoleChecker:
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def __init__(self, required_roles: List[str]):
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self.required_roles = required_roles
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def __call__(self, token: str = Depends(oauth2_scheme)):
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try:
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signing_key = jwks_client.get_signing_key_from_jwt(token)
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payload = jwt.decode(
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token,
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signing_key.key,
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algorithms=["RS256"],
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audience=API_CLIENT_ID, # Ensures token was meant for THIS API
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issuer=f"https://sts.windows.net/{TENANT_ID}/"
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)
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# 1. Validate Scope (Client permission)
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scopes = payload.get("scp", "").split()
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if "user_impersonation" not in scopes:
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raise HTTPException(status_code=403, detail="Invalid token scope.")
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# 2. Validate RBAC Roles (User permission)
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user_roles = payload.get("roles", []) # Entra App Roles array
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# Check if user has at least one of the required roles
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if not any(role in user_roles for role in self.required_roles):
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raise HTTPException(
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status_code=status.HTTP_403_FORBIDDEN,
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detail="User does not have the required application role."
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)
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return payload
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except jwt.ExpiredSignatureError:
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raise HTTPException(status_code=401, detail="Token expired")
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except jwt.InvalidTokenError as e:
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raise HTTPException(status_code=401, detail=f"Invalid token: {str(e)}")
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app = FastAPI()
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@app.get("/admin/reports")
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def get_reports(current_user = Depends(EntraRoleChecker(["API.Admin"]))):
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return {"data": "Sensitive Admin Reports", "authenticated_as": current_user.get("name")} |