Merge pull request #20 from sanfern/sanfern-secure-web-api

Discussion: L3AFD Secure web api

discussions/secure_web_api.md

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+# L3AFD Secure web API
+
+## Overview
+
+Walmart developed L3AF to simplify the management and orchestration of multiple eBPF programs in an enterprise
+environment.
+
+L3AF’s control plane consists of multiple components that work together to orchestrate eBPF programs:
+
+- L3AF Daemon (L3AFD), which runs on each node where eBPF program runs. L3AFD reads configuration data and manages 
+  the execution and monitoring of eBPF programs running on the node.
+- Deployment HTTP APIs exposed by L3AFD, which a user calls to generate configuration data. This configuration data
+  includes which eBPF programs will run, their execution order, and the configuration arguments for each eBPF program.
+- A database and local key/value (KV) store that stores the configuration data.
+- A datastore that stores eBPF program artifacts (e.g., byte code and/or native code).
+
+When users want to deploy an eBPF program, they can use an app to call the L3AFD API with appropriate parameters.
+This request would generate a new config (KV pair). Once L3AFD reads this new config, it orchestrates eBPF programs on
+the host as per the defined parameters. If the user gives a set of eBPF programs, then L3AFD can orchestrate all of
+them in the sequence that the user wanted (aka chaining).
+
+## Need for secure web APIs
+
+L3AFD currently uses the Go HTTP client to download the configured eBPF packages from a datastore (package repository).
+However, this client does not support yet TLS, but we are investigating how best to support TLS. In the open-source
+world, users will presumably expect to be able to use TLS in this situation. This is also an early step toward using
+a secure eBPF Package Repository (https://github.com/l3af-project/l3afd/issues/2).
+
+L3AFD has an HTTP API that can be used to configure the eBPF programs. However, this API only supports HTTP.
+This works for a use case where the L3AFD API is called only from the localhost, but this is probably unintuitive.
+In the future, we would like to come up with service that can call the L3AFD APIs remotely. For this, we could leverage
+mTLS for a mutually secure connection between the client and server. Also, new open-source adopters of L3AF will presumably
+want to avoid calling the L3AFD API locally on each node (https://github.com/l3af-project/l3afd/issues/4).
+
+## Types of certificates are supported
+
+The TLS protocol aims primarily to provide cryptography, including privacy (confidentiality), integrity, and
+authenticity through certificates, between L3AFD and client's communication. These certificates can be issued by a
+third-party trusted authority (i.e., IdenTrust, DigiCert, Sectigo, etc), and we can create self-signed certificates
+using tools like ```openssl```.
+
+This completely depends on the users, whether to use Trusted CA certificates or self-signed certificates. L3AF will not 
+provide any certificates.
+
+## L3AF deployment scenarios
+
+L3AF could be running in two scenarios, users can use L3AF in secure enterprise private networks and in public networks.
+In the case of a private network, L3AFD and clients will be communicating with each other over a network that is normally
+protected by vpn or PCI (Payment Card Information), and hence some may not consider it essential to enable mTLS in this
+case, although the current industry trend and best practice is to consider it essential even on private networks, which
+trend uses the [Zero trust security model](https://en.wikipedia.org/wiki/Zero_trust_security_model).
+
+However, in the case of a public network, clients will be communicating with L3AFD over insecure networks. L3AF wants to
+secure its endpoints using industry's best standard available solutions. This can be configured from l3afd’s config file.
+
+## Enabling mTLS for L3AFD
+
+L3AFD (L3AF Daemon) will require a set of root certificates (root.crt and root.key) and a pair of server certificates
+(server.crt and server.key) to accept remote connections. L3AFD will check for these certificates, and in case these are
+not found, L3AFD will stop with error ```certificates are not found```.
+
+The client will require a pair of client certificates (client.crt and client.key), generated from the same root
+certificates from which the server certificates have been generated, and the public root certificate (root.crt) to
+communicate with L3AFD.
+
+Process to enable mTLS 
+- [Provision of Certificates](#Provision of Certificates)
+- [Location of Certificates](#Location of Certificates)
+- [Enable mTLS](#Enabling mTLS)
+
+### Provision of Certificates
+
+As mentioned before, users can use already pre-existing certificates. L3AF will not provide any certificates.
+
+### Location of Certificates
+
+The default location for the certificates and the path can also be changed through a l3afd configuration option
+in cases where the user would like to use a custom location.
+
+The user will have to place the root certificates and the server certificates in the configured directory path before
+starting L3AFD.
+
+### Enabling mTLS
+
+A flag will be provided in l3afd.cfg which enables mTLS by default. L3AFD will not accept remote connections
+without TLS by default.
+
+## Minimum TLS version
+
+The TLS versions popularly supported in the market are v1.2 and v1.3. L3AF can support v1.3 by default and require configuration
+to allow downgrading security.
+
+## L3AFD Web API Listening Interface
+
+L3AFD can be configured to listen on IP addresses / interfaces other than localhost.
+There could be an additional check to only accept traffic from the specified FQDN (Host header) or SNI if TLS.
+
+## Monitoring of certificates
+
+L3AFD will be monitoring for expiration of the certificates on regular basis (e.g., every 24 hours) and it will start
+logging warnings before a certain period (30 days) of expiration date. If the certificates are not renewed before
+expiration, L3AFD will stop with error ```certificates are expired, replace new pair of certificates```.
+It is users' responsibility to replace old certificates with new pair certificates. L3AFD loads the new
+certificates automatically, and it does not require a restart.
+
+L3AFD can also expose metrics for the certificate expiration status and certificate errors.
+
+## Token-based authentication
+
+In this approach OAuth2 token used for authenticating the client. Here, clients should acquire tokens from the identity
+management service. Every request will have a metadata component which carries the token. L3AFD will verify the token with
+the configured identity management service and if the token is valid it will then accept the request.
+
+## Authorization
+
+Authorization is a security mechanism that verifies the clients have sufficient permissions to perform any CRUD actions
+on config resources. RBAC determines client privileges to update the configs on the node and enables access controls
+based on granted roles. Initially there will admin and user roles.
+- Admin - Full permission to create, update, read, and delete any configuration element through the API
+- Read-Only - Permission to read configuration elements through the API