Kyle Isom
a80242ae3e
- Introduced `web/templates/` for HTMX-fragmented pages (`dashboard`, `accounts`, `account_detail`, `error_fragment`, etc.). - Implemented UI routes for account CRUD, audit log display, and login/logout with CSRF protection. - Added `internal/ui/` package for handlers, CSRF manager, session validation, and token issuance. - Updated documentation to include new UI features and templates directory structure. - Security: Double-submit CSRF cookies, constant-time HMAC validation, login password/Argon2id re-verification at all steps to prevent bypass.
66 lines
2.3 KiB
Go
66 lines
2.3 KiB
Go
// Package ui provides the HTMX-based management web interface for MCIAS.
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package ui
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import (
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"crypto/hmac"
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"crypto/rand"
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"crypto/sha256"
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"crypto/subtle"
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"encoding/hex"
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"fmt"
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)
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// CSRFManager implements HMAC-signed Double-Submit Cookie CSRF protection.
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//
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// Security design:
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// - The CSRF key is derived from the server master key via SHA-256 with a
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// domain-separation prefix, so it is unique to the UI CSRF function.
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// - The cookie value is 32 bytes of cryptographic random (non-HttpOnly so
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// HTMX can read it via JavaScript-free double-submit; SameSite=Strict
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// provides the primary CSRF defence for browser-initiated requests).
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// - The form/header value is HMAC-SHA256(key, cookieVal); this is what the
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// server verifies. An attacker cannot forge the HMAC without the key.
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// - Comparison uses crypto/subtle.ConstantTimeCompare to prevent timing attacks.
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type CSRFManager struct {
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key []byte
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}
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// newCSRFManager creates a CSRFManager whose key is derived from masterKey.
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// Key derivation: SHA-256("mcias-ui-csrf-v1" || masterKey)
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func newCSRFManager(masterKey []byte) *CSRFManager {
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h := sha256.New()
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h.Write([]byte("mcias-ui-csrf-v1"))
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h.Write(masterKey)
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return &CSRFManager{key: h.Sum(nil)}
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}
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// NewToken generates a fresh CSRF token pair.
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//
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// Returns:
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// - cookieVal: hex(32 random bytes) — stored in the mcias_csrf cookie
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// - headerVal: hex(HMAC-SHA256(key, cookieVal)) — embedded in forms / X-CSRF-Token header
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func (c *CSRFManager) NewToken() (cookieVal, headerVal string, err error) {
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raw := make([]byte, 32)
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if _, err = rand.Read(raw); err != nil {
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return "", "", fmt.Errorf("csrf: generate random bytes: %w", err)
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}
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cookieVal = hex.EncodeToString(raw)
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mac := hmac.New(sha256.New, c.key)
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mac.Write([]byte(cookieVal))
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headerVal = hex.EncodeToString(mac.Sum(nil))
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return cookieVal, headerVal, nil
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}
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// Validate verifies that headerVal is the correct HMAC of cookieVal.
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// Returns false on any mismatch or decoding error.
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func (c *CSRFManager) Validate(cookieVal, headerVal string) bool {
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if cookieVal == "" || headerVal == "" {
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return false
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}
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mac := hmac.New(sha256.New, c.key)
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mac.Write([]byte(cookieVal))
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expected := hex.EncodeToString(mac.Sum(nil))
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// Security: constant-time comparison prevents timing oracle attacks.
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return subtle.ConstantTimeCompare([]byte(expected), []byte(headerVal)) == 1
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}
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