auth: Add HTTP-based authentication support to validate domain ownership (#282)
Add HTTP-based authentication to prove domain ownership, similar to https://github.com/modelcontextprotocol/registry/pull/238's DNS authentication but using HTTPS well-known URIs instead of DNS TXT records. Fixes #280 ## Motivation and Context Some organizations don't have easy access to DNS records, but can easily deploy web assets. They would therefore prefer to be able to complete a HTTP challenge rather than a DNS one to authenticate to the registry. This would in some way mirror ACME challenges: where you can do a DNS-01 or a HTTP-01 challenge. ## How Has This Been Tested? - Tested locally by stubbing out the HTTP getter - Added unit tests ## Breaking Changes None ## Types of changes <!-- What types of changes does your code introduce? Put an `x` in all the boxes that apply: --> - [ ] Bug fix (non-breaking change which fixes an issue) - [x] New feature (non-breaking change which adds functionality) - [ ] Breaking change (fix or feature that would cause existing functionality to change) - [ ] Documentation update ## Checklist <!-- Go over all the following points, and put an `x` in all the boxes that apply. --> - [x] I have read the [MCP Documentation](https://modelcontextprotocol.io) - [x] My code follows the repository's style guidelines - [x] New and existing tests pass locally - [x] I have added appropriate error handling - [x] I have added or updated documentation as needed ## Additional context I concern I had when building this that it might expose us to SSRF attacks. I think on reflection this is not a significant problem: - We only GET a fixed file `.well-known/mcp-registry-auth` (redirects disallowed) after sanitizing the domain, and then also don't expose the response to the user. This means the user shouldn't be able to hit anything very interesting. - The information they might get is what domains/servers exist in the network. Our infrastructure is already all open-source, so attackers aren't getting any additional real info by prodding at the environment this way.
This commit is contained in:
adam jones
GitHub
parent
316cbb08ee
commit
ee910ca286
3 changed files with 678 additions and 118 deletions
238
internal/api/handlers/v0/auth/http.go
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238
internal/api/handlers/v0/auth/http.go
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@ -0,0 +1,238 @@
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package auth
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import (
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"context"
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"crypto/ed25519"
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"encoding/base64"
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"encoding/hex"
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"fmt"
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"io"
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"net/http"
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"regexp"
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"strings"
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"time"
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"github.com/danielgtaylor/huma/v2"
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v0 "github.com/modelcontextprotocol/registry/internal/api/handlers/v0"
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"github.com/modelcontextprotocol/registry/internal/auth"
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"github.com/modelcontextprotocol/registry/internal/config"
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"github.com/modelcontextprotocol/registry/internal/model"
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)
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// HTTPTokenExchangeInput represents the input for HTTP-based authentication
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type HTTPTokenExchangeInput struct {
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Body struct {
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Domain string `json:"domain" doc:"Domain name" example:"example.com" required:"true"`
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Timestamp string `json:"timestamp" doc:"RFC3339 timestamp" example:"2023-01-01T00:00:00Z" required:"true"`
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SignedTimestamp string `json:"signed_timestamp" doc:"Hex-encoded Ed25519 signature of timestamp" example:"abcdef1234567890" required:"true"`
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}
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}
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// HTTPKeyFetcher defines the interface for fetching HTTP keys
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type HTTPKeyFetcher interface {
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FetchKey(ctx context.Context, domain string) (string, error)
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}
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// DefaultHTTPKeyFetcher uses Go's standard HTTP client
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type DefaultHTTPKeyFetcher struct {
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client *http.Client
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}
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// NewDefaultHTTPKeyFetcher creates a new HTTP key fetcher with timeout
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func NewDefaultHTTPKeyFetcher() *DefaultHTTPKeyFetcher {
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return &DefaultHTTPKeyFetcher{
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client: &http.Client{
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Timeout: 10 * time.Second,
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// Disable redirects for security purposes:
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// Prevents people doing weird things like sending us to internal endpoints at different paths
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CheckRedirect: func(_ *http.Request, _ []*http.Request) error {
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return http.ErrUseLastResponse
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},
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},
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}
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}
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// FetchKey fetches the public key from the well-known HTTP endpoint
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func (f *DefaultHTTPKeyFetcher) FetchKey(ctx context.Context, domain string) (string, error) {
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url := fmt.Sprintf("https://%s/.well-known/mcp-registry-auth", domain)
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
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if err != nil {
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return "", fmt.Errorf("failed to create request: %w", err)
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}
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req.Header.Set("Accept", "text/plain")
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req.Header.Set("User-Agent", "mcp-registry/1.0")
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resp, err := f.client.Do(req)
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if err != nil {
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return "", fmt.Errorf("failed to fetch key: %w", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return "", fmt.Errorf("HTTP %d: failed to fetch key from %s", resp.StatusCode, url)
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}
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// Limit response size to prevent DoS attacks
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resp.Body = http.MaxBytesReader(nil, resp.Body, 4096)
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body, err := io.ReadAll(resp.Body)
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if err != nil {
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return "", fmt.Errorf("failed to read response body: %w", err)
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}
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return strings.TrimSpace(string(body)), nil
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}
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// HTTPAuthHandler handles HTTP-based authentication
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type HTTPAuthHandler struct {
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config *config.Config
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jwtManager *auth.JWTManager
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fetcher HTTPKeyFetcher
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}
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// NewHTTPAuthHandler creates a new HTTP authentication handler
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func NewHTTPAuthHandler(cfg *config.Config) *HTTPAuthHandler {
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return &HTTPAuthHandler{
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config: cfg,
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jwtManager: auth.NewJWTManager(cfg),
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fetcher: NewDefaultHTTPKeyFetcher(),
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}
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}
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// SetFetcher sets a custom HTTP key fetcher (used for testing)
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func (h *HTTPAuthHandler) SetFetcher(fetcher HTTPKeyFetcher) {
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h.fetcher = fetcher
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}
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// RegisterHTTPEndpoint registers the HTTP authentication endpoint
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func RegisterHTTPEndpoint(api huma.API, cfg *config.Config) {
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handler := NewHTTPAuthHandler(cfg)
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// HTTP authentication endpoint
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huma.Register(api, huma.Operation{
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OperationID: "exchange-http-token",
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Method: http.MethodPost,
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Path: "/v0/auth/http",
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Summary: "Exchange HTTP signature for Registry JWT",
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Description: "Authenticate using HTTP-hosted public key and signed timestamp",
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Tags: []string{"auth"},
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}, func(ctx context.Context, input *HTTPTokenExchangeInput) (*v0.Response[auth.TokenResponse], error) {
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response, err := handler.ExchangeToken(ctx, input.Body.Domain, input.Body.Timestamp, input.Body.SignedTimestamp)
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if err != nil {
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return nil, huma.Error401Unauthorized("HTTP authentication failed", err)
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}
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return &v0.Response[auth.TokenResponse]{
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Body: *response,
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}, nil
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})
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}
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// ExchangeToken exchanges HTTP signature for a Registry JWT token
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func (h *HTTPAuthHandler) ExchangeToken(ctx context.Context, domain, timestamp, signedTimestamp string) (*auth.TokenResponse, error) {
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// Validate domain format
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if !isValidDomain(domain) {
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return nil, fmt.Errorf("invalid domain format")
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}
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// Parse and validate timestamp
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ts, err := time.Parse(time.RFC3339, timestamp)
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if err != nil {
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return nil, fmt.Errorf("invalid timestamp format: %w", err)
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}
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// Check timestamp is within 15 seconds
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now := time.Now()
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if ts.Before(now.Add(-15*time.Second)) || ts.After(now.Add(15*time.Second)) {
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return nil, fmt.Errorf("timestamp outside valid window (±15 seconds)")
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}
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// Decode signature
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signature, err := hex.DecodeString(signedTimestamp)
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if err != nil {
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return nil, fmt.Errorf("invalid signature format, must be hex: %w", err)
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}
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if len(signature) != ed25519.SignatureSize {
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return nil, fmt.Errorf("invalid signature length: expected %d, got %d", ed25519.SignatureSize, len(signature))
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}
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// Fetch public key from HTTP endpoint
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keyResponse, err := h.fetcher.FetchKey(ctx, domain)
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if err != nil {
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return nil, fmt.Errorf("failed to fetch public key: %w", err)
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}
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// Parse public key from HTTP response
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publicKey, err := h.parsePublicKeyFromHTTP(keyResponse)
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if err != nil {
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return nil, fmt.Errorf("failed to parse public key: %w", err)
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}
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// Verify signature
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messageBytes := []byte(timestamp)
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if !ed25519.Verify(publicKey, messageBytes, signature) {
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return nil, fmt.Errorf("signature verification failed")
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}
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// Build permissions for domain and subdomains
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permissions := h.buildPermissions(domain)
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// Create JWT claims
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jwtClaims := auth.JWTClaims{
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AuthMethod: model.AuthMethodHTTP,
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AuthMethodSubject: domain,
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Permissions: permissions,
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}
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// Generate Registry JWT token
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tokenResponse, err := h.jwtManager.GenerateTokenResponse(ctx, jwtClaims)
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if err != nil {
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return nil, fmt.Errorf("failed to generate JWT token: %w", err)
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}
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return tokenResponse, nil
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}
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// parsePublicKeyFromHTTP parses Ed25519 public key from HTTP response
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func (h *HTTPAuthHandler) parsePublicKeyFromHTTP(response string) (ed25519.PublicKey, error) {
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// Expected format: v=MCPv1; k=ed25519; p=<base64-encoded-key>
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mcpPattern := regexp.MustCompile(`v=MCPv1;\s*k=ed25519;\s*p=([A-Za-z0-9+/=]+)`)
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matches := mcpPattern.FindStringSubmatch(response)
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if len(matches) != 2 {
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return nil, fmt.Errorf("invalid key format, expected: v=MCPv1; k=ed25519; p=<base64-key>")
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}
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// Decode base64 public key
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publicKeyBytes, err := base64.StdEncoding.DecodeString(matches[1])
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if err != nil {
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return nil, fmt.Errorf("failed to decode base64 public key: %w", err)
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}
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if len(publicKeyBytes) != ed25519.PublicKeySize {
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return nil, fmt.Errorf("invalid public key length: expected %d, got %d", ed25519.PublicKeySize, len(publicKeyBytes))
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}
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return ed25519.PublicKey(publicKeyBytes), nil
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}
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// buildPermissions builds permissions for a domain and its subdomains using reverse DNS notation
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func (h *HTTPAuthHandler) buildPermissions(domain string) []auth.Permission {
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reverseDomain := reverseString(domain)
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permissions := []auth.Permission{
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// Grant permissions for the exact domain (e.g., com.example/*)
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{
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Action: auth.PermissionActionPublish,
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ResourcePattern: fmt.Sprintf("%s/*", reverseDomain),
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},
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// HTTP does not imply a hierarchy of ownership of subdomains, unlike DNS
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// Therefore this does not give permissions for subdomains
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// This is consistent with similar protocols, e.g. ACME HTTP-01
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}
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return permissions
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}
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244
internal/api/handlers/v0/auth/http_test.go
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244
internal/api/handlers/v0/auth/http_test.go
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package auth_test
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import (
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"context"
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"crypto/ed25519"
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"encoding/base64"
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"encoding/hex"
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"fmt"
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"strings"
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"testing"
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"time"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"github.com/modelcontextprotocol/registry/internal/api/handlers/v0/auth"
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intauth "github.com/modelcontextprotocol/registry/internal/auth"
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"github.com/modelcontextprotocol/registry/internal/config"
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"github.com/modelcontextprotocol/registry/internal/model"
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)
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// MockHTTPKeyFetcher for testing
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type MockHTTPKeyFetcher struct {
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keyResponses map[string]string
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err error
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}
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func (m *MockHTTPKeyFetcher) FetchKey(_ context.Context, domain string) (string, error) {
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if m.err != nil {
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return "", m.err
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}
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return m.keyResponses[domain], nil
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}
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func TestHTTPAuthHandler_ExchangeToken(t *testing.T) {
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cfg := &config.Config{
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JWTPrivateKey: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
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}
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handler := auth.NewHTTPAuthHandler(cfg)
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// Generate a test key pair
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publicKey, privateKey, err := ed25519.GenerateKey(nil)
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require.NoError(t, err)
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// Create mock HTTP key fetcher
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publicKeyB64 := base64.StdEncoding.EncodeToString(publicKey)
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mockFetcher := &MockHTTPKeyFetcher{
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keyResponses: map[string]string{
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"example.com": fmt.Sprintf("v=MCPv1; k=ed25519; p=%s", publicKeyB64),
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},
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}
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handler.SetFetcher(mockFetcher)
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tests := []struct {
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name string
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domain string
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timestamp string
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signedTimestamp string
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setupMock func(*MockHTTPKeyFetcher)
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expectError bool
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errorContains string
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}{
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{
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name: "successful authentication",
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domain: "example.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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setupMock: func(_ *MockHTTPKeyFetcher) {
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// Mock is already set up with valid key
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},
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expectError: false,
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},
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{
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name: "invalid domain format",
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domain: "invalid..domain",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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expectError: true,
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errorContains: "invalid domain format",
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},
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{
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name: "invalid timestamp format",
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domain: "example.com",
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timestamp: "invalid-timestamp",
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expectError: true,
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errorContains: "invalid timestamp format",
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},
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{
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name: "timestamp too old",
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domain: "example.com",
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timestamp: time.Now().Add(-30 * time.Second).UTC().Format(time.RFC3339),
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expectError: true,
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errorContains: "timestamp outside valid window",
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},
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{
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name: "timestamp too far in the future",
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domain: "example.com",
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timestamp: time.Now().Add(30 * time.Second).UTC().Format(time.RFC3339),
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expectError: true,
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errorContains: "timestamp outside valid window",
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},
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{
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name: "invalid signature format",
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domain: "example.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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signedTimestamp: "invalid-hex",
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expectError: true,
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errorContains: "invalid signature format",
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},
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{
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name: "signature wrong length",
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domain: "example.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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signedTimestamp: "abcdef", // too short
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expectError: true,
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errorContains: "invalid signature length",
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},
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{
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name: "HTTP key fetch failure",
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domain: "nonexistent.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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setupMock: func(m *MockHTTPKeyFetcher) {
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m.err = fmt.Errorf("HTTP 404: not found")
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},
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expectError: true,
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errorContains: "failed to fetch public key",
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},
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{
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name: "invalid key format",
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domain: "invalidkey.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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setupMock: func(m *MockHTTPKeyFetcher) {
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m.keyResponses["invalidkey.com"] = "invalid key format"
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m.err = nil
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},
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expectError: true,
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errorContains: "invalid key format",
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},
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{
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name: "invalid base64 key",
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domain: "badkey.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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setupMock: func(m *MockHTTPKeyFetcher) {
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m.keyResponses["badkey.com"] = "v=MCPv1; k=ed25519; p=invalid-base64!!!"
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m.err = nil
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},
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expectError: true,
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errorContains: "failed to decode base64 public key",
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},
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{
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name: "wrong key size",
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domain: "wrongsize.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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setupMock: func(m *MockHTTPKeyFetcher) {
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// Generate a key that's too short
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shortKey := base64.StdEncoding.EncodeToString([]byte("short"))
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m.keyResponses["wrongsize.com"] = fmt.Sprintf("v=MCPv1; k=ed25519; p=%s", shortKey)
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m.err = nil
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},
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expectError: true,
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errorContains: "invalid public key length",
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},
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{
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name: "signature verification failure",
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domain: "example.com",
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timestamp: time.Now().UTC().Format(time.RFC3339),
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setupMock: func(m *MockHTTPKeyFetcher) {
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// Generate different key pair for signature verification failure
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wrongPublicKey, _, err := ed25519.GenerateKey(nil)
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require.NoError(t, err)
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wrongPublicKeyB64 := base64.StdEncoding.EncodeToString(wrongPublicKey)
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m.keyResponses["example.com"] = fmt.Sprintf("v=MCPv1; k=ed25519; p=%s", wrongPublicKeyB64)
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m.err = nil
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},
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expectError: true,
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errorContains: "signature verification failed",
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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// Reset mock fetcher
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mockFetcher.err = nil
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if tt.setupMock != nil {
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tt.setupMock(mockFetcher)
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}
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// Generate signature if not provided
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signedTimestamp := tt.signedTimestamp
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if signedTimestamp == "" {
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// Generate a valid signature for all cases
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signature := ed25519.Sign(privateKey, []byte(tt.timestamp))
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signedTimestamp = hex.EncodeToString(signature)
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}
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// Call the handler
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result, err := handler.ExchangeToken(context.Background(), tt.domain, tt.timestamp, signedTimestamp)
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if tt.expectError {
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assert.Error(t, err)
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if tt.errorContains != "" {
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assert.Contains(t, err.Error(), tt.errorContains)
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}
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assert.Nil(t, result)
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} else {
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assert.NoError(t, err)
|
||||
assert.NotNil(t, result)
|
||||
assert.NotEmpty(t, result.RegistryToken)
|
||||
|
||||
// Verify the token contains expected claims
|
||||
jwtManager := intauth.NewJWTManager(cfg)
|
||||
claims, err := jwtManager.ValidateToken(context.Background(), result.RegistryToken)
|
||||
require.NoError(t, err)
|
||||
|
||||
assert.Equal(t, model.AuthMethodHTTP, claims.AuthMethod)
|
||||
assert.Equal(t, tt.domain, claims.AuthMethodSubject)
|
||||
assert.Len(t, claims.Permissions, 1) // domain permissions only
|
||||
|
||||
// Check permissions use reverse DNS patterns
|
||||
patterns := make([]string, len(claims.Permissions))
|
||||
for i, perm := range claims.Permissions {
|
||||
patterns[i] = perm.ResourcePattern
|
||||
}
|
||||
// Convert domain to reverse DNS for expected patterns
|
||||
parts := strings.Split(tt.domain, ".")
|
||||
for i, j := 0, len(parts)-1; i < j; i, j = i+1, j-1 {
|
||||
parts[i], parts[j] = parts[j], parts[i]
|
||||
}
|
||||
reverseDomain := strings.Join(parts, ".")
|
||||
assert.Contains(t, patterns, fmt.Sprintf("%s/*", reverseDomain))
|
||||
}
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
func TestDefaultHTTPKeyFetcher_FetchKey(t *testing.T) {
|
||||
// This test would require a real HTTP server or more sophisticated mocking
|
||||
// For now, we'll test the basic structure
|
||||
fetcher := auth.NewDefaultHTTPKeyFetcher()
|
||||
assert.NotNil(t, fetcher)
|
||||
|
||||
// Test that it returns an error for non-existent domains
|
||||
// (This will fail with network error, which is expected)
|
||||
_, err := fetcher.FetchKey(context.Background(), "nonexistent-test-domain-12345.com")
|
||||
assert.Error(t, err)
|
||||
}
|
||||
|
|
@ -16,6 +16,9 @@ func RegisterAuthEndpoints(api huma.API, cfg *config.Config) {
|
|||
// Register DNS-based authentication endpoint
|
||||
RegisterDNSEndpoint(api, cfg)
|
||||
|
||||
// Register HTTP-based authentication endpoint
|
||||
RegisterHTTPEndpoint(api, cfg)
|
||||
|
||||
// Register anonymous authentication endpoint
|
||||
RegisterNoneEndpoint(api, cfg)
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue