Add AWS OIDC outgoing auth plugin #575
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,218 @@ | ||
| package awsimds | ||
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| import ( | ||
| "context" | ||
| "encoding/json" | ||
| "fmt" | ||
| "io" | ||
| "net/http" | ||
| "strings" | ||
| "sync" | ||
| "time" | ||
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| authplugins "github.com/winhowes/AuthTranslator/app/auth" | ||
| ) | ||
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| // awsIMDSParams configures the AWS IMDS plugin. | ||
| type awsIMDSParams struct { | ||
| Header string `json:"header"` | ||
| Prefix string `json:"prefix"` | ||
| } | ||
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| // AWSIMDS fetches the IAM role session token from the AWS Instance Metadata | ||
| // Service (IMDSv2) and adds it to outgoing requests. | ||
| type AWSIMDS struct{} | ||
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| // MetadataHost is the base URL for the AWS metadata service. It can be | ||
| // overridden in tests. | ||
| var MetadataHost = "http://169.254.169.254" | ||
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| // HTTPClient is used for all metadata requests. | ||
| var HTTPClient = &http.Client{Timeout: 5 * time.Second} | ||
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| var tokenCache = struct { | ||
| sync.Mutex | ||
| ct cachedToken | ||
| }{ct: cachedToken{}} | ||
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| type cachedToken struct { | ||
| token string | ||
| exp time.Time | ||
| } | ||
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| // AWSOIDC is kept as a backward-compatible alias for configurations still | ||
| // referencing the old plugin name. It delegates all behavior to AWSIMDS but | ||
| // advertises the legacy `aws_oidc` name. | ||
| type AWSOIDC struct{ AWSIMDS } | ||
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| func (a *AWSOIDC) Name() string { return "aws_oidc" } | ||
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| func (a *AWSIMDS) Name() string { return "aws_imds" } | ||
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| func (a *AWSIMDS) RequiredParams() []string { return nil } | ||
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| func (a *AWSIMDS) OptionalParams() []string { return []string{"header", "prefix"} } | ||
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| func (a *AWSIMDS) ParseParams(m map[string]interface{}) (interface{}, error) { | ||
| p, err := authplugins.ParseParams[awsIMDSParams](m) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| if p.Header == "" { | ||
| p.Header = "Authorization" | ||
| } | ||
| if p.Prefix == "" { | ||
| p.Prefix = "Bearer " | ||
| } | ||
| return p, nil | ||
| } | ||
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| func (a *AWSIMDS) AddAuth(ctx context.Context, r *http.Request, params interface{}) error { | ||
| cfg, ok := params.(*awsIMDSParams) | ||
| if !ok { | ||
| return fmt.Errorf("invalid config") | ||
| } | ||
| tok, exp := getCachedToken() | ||
| if tok == "" || time.Now().After(exp.Add(-1*time.Minute)) { | ||
| var err error | ||
| tok, exp, err = fetchToken(ctx) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| setCachedToken(tok, exp) | ||
| } | ||
| r.Header.Set(cfg.Header, cfg.Prefix+tok) | ||
| return nil | ||
| } | ||
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| func fetchToken(ctx context.Context) (string, time.Time, error) { | ||
| metaToken, err := fetchMetadataToken(ctx) | ||
| if err != nil { | ||
| return "", time.Time{}, err | ||
| } | ||
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| roleName, err := fetchRoleName(ctx, metaToken) | ||
| if err != nil { | ||
| return "", time.Time{}, err | ||
| } | ||
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| credentials, err := fetchRoleCredentials(ctx, metaToken, roleName) | ||
| if err != nil { | ||
| return "", time.Time{}, err | ||
| } | ||
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| if credentials.Token == "" { | ||
| return "", time.Time{}, fmt.Errorf("empty session token from IMDS for role %s", roleName) | ||
| } | ||
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| exp, err := time.Parse(time.RFC3339, credentials.Expiration) | ||
| if err != nil { | ||
| return "", time.Time{}, fmt.Errorf("parse expiration: %w", err) | ||
| } | ||
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| return credentials.Token, exp, nil | ||
| } | ||
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| func fetchMetadataToken(ctx context.Context) (string, error) { | ||
| tokenURL := fmt.Sprintf("%s/latest/api/token", MetadataHost) | ||
| req, err := http.NewRequestWithContext(ctx, http.MethodPut, tokenURL, nil) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| req.Header.Set("X-aws-ec2-metadata-token-ttl-seconds", "21600") | ||
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| resp, err := HTTPClient.Do(req) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| defer resp.Body.Close() | ||
| if resp.StatusCode != http.StatusOK { | ||
| body, _ := io.ReadAll(resp.Body) | ||
| return "", fmt.Errorf("token fetch status %s: %s", resp.Status, body) | ||
| } | ||
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| tokenBytes, err := io.ReadAll(resp.Body) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| return string(tokenBytes), nil | ||
| } | ||
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| func fetchRoleName(ctx context.Context, metaToken string) (string, error) { | ||
| roleURL := fmt.Sprintf("%s/latest/meta-data/iam/security-credentials/", MetadataHost) | ||
| req, err := http.NewRequestWithContext(ctx, http.MethodGet, roleURL, nil) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| req.Header.Set("X-aws-ec2-metadata-token", metaToken) | ||
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| resp, err := HTTPClient.Do(req) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| defer resp.Body.Close() | ||
| if resp.StatusCode != http.StatusOK { | ||
| body, _ := io.ReadAll(resp.Body) | ||
| return "", fmt.Errorf("role name status %s: %s", resp.Status, body) | ||
| } | ||
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| roleBytes, err := io.ReadAll(resp.Body) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
| roleName := strings.TrimSpace(string(roleBytes)) | ||
| if roleName == "" { | ||
| return "", fmt.Errorf("empty role name from IMDS") | ||
| } | ||
| return roleName, nil | ||
| } | ||
|
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| type roleCredentials struct { | ||
| Expiration string `json:"Expiration"` | ||
| Token string `json:"Token"` | ||
| } | ||
|
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| func fetchRoleCredentials(ctx context.Context, metaToken, roleName string) (*roleCredentials, error) { | ||
| credsURL := fmt.Sprintf("%s/latest/meta-data/iam/security-credentials/%s", MetadataHost, roleName) | ||
| req, err := http.NewRequestWithContext(ctx, http.MethodGet, credsURL, nil) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| req.Header.Set("X-aws-ec2-metadata-token", metaToken) | ||
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| resp, err := HTTPClient.Do(req) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| defer resp.Body.Close() | ||
| if resp.StatusCode != http.StatusOK { | ||
| body, _ := io.ReadAll(resp.Body) | ||
| return nil, fmt.Errorf("role credentials status %s: %s", resp.Status, body) | ||
| } | ||
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| var rc roleCredentials | ||
| if err := json.NewDecoder(resp.Body).Decode(&rc); err != nil { | ||
| return nil, err | ||
| } | ||
| if rc.Expiration == "" { | ||
| return nil, fmt.Errorf("missing expiration in role credentials") | ||
| } | ||
| return &rc, nil | ||
| } | ||
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| func getCachedToken() (string, time.Time) { | ||
| tokenCache.Lock() | ||
| defer tokenCache.Unlock() | ||
| return tokenCache.ct.token, tokenCache.ct.exp | ||
| } | ||
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| func setCachedToken(tok string, exp time.Time) { | ||
| tokenCache.Lock() | ||
| tokenCache.ct = cachedToken{token: tok, exp: exp} | ||
| tokenCache.Unlock() | ||
| } | ||
|
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| func init() { | ||
| authplugins.RegisterOutgoing(&AWSIMDS{}) | ||
| authplugins.RegisterOutgoing(&AWSOIDC{}) | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,162 @@ | ||
| package awsimds | ||
|
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| import ( | ||
| "context" | ||
| "encoding/json" | ||
| "net/http" | ||
| "net/http/httptest" | ||
| "testing" | ||
| "time" | ||
| ) | ||
|
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| func TestAddAuthFetchesAndCachesToken(t *testing.T) { | ||
| expires := time.Now().Add(2 * time.Minute).UTC().Truncate(time.Second) | ||
| sessionToken := "sts-session-token" | ||
| metaToken := "meta123" | ||
| roleName := "example-role" | ||
| var requestCount int | ||
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| srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | ||
| switch r.URL.Path { | ||
| case "/latest/api/token": | ||
| requestCount++ | ||
| if r.Method != http.MethodPut { | ||
| t.Fatalf("expected PUT for token, got %s", r.Method) | ||
| } | ||
| if ttl := r.Header.Get("X-aws-ec2-metadata-token-ttl-seconds"); ttl == "" { | ||
| t.Fatalf("missing TTL header") | ||
| } | ||
| w.Write([]byte(metaToken)) | ||
| case "/latest/meta-data/iam/security-credentials/": | ||
| requestCount++ | ||
| if got := r.Header.Get("X-aws-ec2-metadata-token"); got != metaToken { | ||
| t.Fatalf("expected metadata token %q, got %q", metaToken, got) | ||
| } | ||
| w.Write([]byte(roleName)) | ||
| case "/latest/meta-data/iam/security-credentials/" + roleName: | ||
| requestCount++ | ||
| if got := r.Header.Get("X-aws-ec2-metadata-token"); got != metaToken { | ||
| t.Fatalf("expected metadata token %q, got %q", metaToken, got) | ||
| } | ||
| json.NewEncoder(w).Encode(map[string]interface{}{ | ||
| "Token": sessionToken, | ||
| "Expiration": expires.Format(time.RFC3339), | ||
| }) | ||
| default: | ||
| t.Fatalf("unexpected path %s", r.URL.Path) | ||
| } | ||
| })) | ||
| defer srv.Close() | ||
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| MetadataHost = srv.URL | ||
| HTTPClient = srv.Client() | ||
| tokenCache.ct = cachedToken{} | ||
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| plugin := &AWSIMDS{} | ||
| paramsRaw, err := plugin.ParseParams(map[string]interface{}{}) | ||
| if err != nil { | ||
| t.Fatalf("parse params: %v", err) | ||
| } | ||
| req, _ := http.NewRequest(http.MethodGet, "http://example.com", nil) | ||
| if err := plugin.AddAuth(context.Background(), req, paramsRaw); err != nil { | ||
| t.Fatalf("AddAuth: %v", err) | ||
| } | ||
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| if got := req.Header.Get("Authorization"); got != "Bearer "+sessionToken { | ||
| t.Fatalf("unexpected header: %s", got) | ||
| } | ||
| if requestCount != 3 { | ||
| t.Fatalf("expected 3 metadata requests, got %d", requestCount) | ||
| } | ||
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| // Second call should use cache. | ||
| req2, _ := http.NewRequest(http.MethodGet, "http://example.com", nil) | ||
| if err := plugin.AddAuth(context.Background(), req2, paramsRaw); err != nil { | ||
| t.Fatalf("AddAuth second: %v", err) | ||
| } | ||
| if requestCount != 3 { | ||
| t.Fatalf("expected cached token, still %d requests", requestCount) | ||
| } | ||
| } | ||
|
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| func TestExpiresSoonTriggersRefresh(t *testing.T) { | ||
| expSoon := time.Now().Add(30 * time.Second).UTC().Truncate(time.Second) | ||
| expLater := time.Now().Add(10 * time.Minute).UTC().Truncate(time.Second) | ||
| metaToken := "meta123" | ||
| roleName := "role" | ||
| sessionTokens := []string{"first", "second"} | ||
| var credIndex int | ||
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| srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | ||
| switch r.URL.Path { | ||
| case "/latest/api/token": | ||
| w.Write([]byte(metaToken)) | ||
| case "/latest/meta-data/iam/security-credentials/": | ||
| w.Write([]byte(roleName)) | ||
| case "/latest/meta-data/iam/security-credentials/" + roleName: | ||
| exp := expSoon | ||
| if credIndex > 0 { | ||
| exp = expLater | ||
| } | ||
| json.NewEncoder(w).Encode(map[string]interface{}{ | ||
| "Token": sessionTokens[credIndex], | ||
| "Expiration": exp.Format(time.RFC3339), | ||
| }) | ||
| credIndex++ | ||
| default: | ||
| t.Fatalf("unexpected path %s", r.URL.Path) | ||
| } | ||
| })) | ||
| defer srv.Close() | ||
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| MetadataHost = srv.URL | ||
| HTTPClient = srv.Client() | ||
| tokenCache.ct = cachedToken{} | ||
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| plugin := &AWSIMDS{} | ||
| paramsRaw, err := plugin.ParseParams(map[string]interface{}{}) | ||
| if err != nil { | ||
| t.Fatalf("parse params: %v", err) | ||
| } | ||
| req, _ := http.NewRequest(http.MethodGet, "http://example.com", nil) | ||
| if err := plugin.AddAuth(context.Background(), req, paramsRaw); err != nil { | ||
| t.Fatalf("AddAuth: %v", err) | ||
| } | ||
| req2, _ := http.NewRequest(http.MethodGet, "http://example.com", nil) | ||
| if err := plugin.AddAuth(context.Background(), req2, paramsRaw); err != nil { | ||
| t.Fatalf("AddAuth second: %v", err) | ||
| } | ||
| if credIndex != 2 { | ||
| t.Fatalf("expected token refresh, stage %d", credIndex) | ||
| } | ||
| } | ||
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| func TestErrorResponses(t *testing.T) { | ||
| srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | ||
| switch r.URL.Path { | ||
| case "/latest/api/token": | ||
| w.WriteHeader(http.StatusBadRequest) | ||
| w.Write([]byte("no token")) | ||
| case "/latest/meta-data/iam/security-credentials/": | ||
| w.WriteHeader(http.StatusBadRequest) | ||
| w.Write([]byte("no role")) | ||
| default: | ||
| t.Fatalf("unexpected path %s", r.URL.Path) | ||
| } | ||
| })) | ||
| defer srv.Close() | ||
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| MetadataHost = srv.URL | ||
| HTTPClient = srv.Client() | ||
| tokenCache.ct = cachedToken{} | ||
|
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| plugin := &AWSIMDS{} | ||
| paramsRaw, err := plugin.ParseParams(map[string]interface{}{}) | ||
| if err != nil { | ||
| t.Fatalf("parse params: %v", err) | ||
| } | ||
| req, _ := http.NewRequest(http.MethodGet, "http://example.com", nil) | ||
| if err := plugin.AddAuth(context.Background(), req, paramsRaw); err == nil { | ||
| t.Fatalf("expected error from metadata token fetch") | ||
| } | ||
| } |
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The metadata client is instantiated with the default transport, which honors
HTTP(S)_PROXY(lines 36-37). In environments where those env vars are set—a common case on EC2—the IMDS calls will be routed through the proxy, leaking the session token/credentials and often failing to reach 169.254.169.254 at all. AWS SDKs explicitly disable proxies for IMDS requests; the plugin should do the same (e.g., set a transport withProxy: nil) to avoid credential exposure and spurious failures.Useful? React with 👍 / 👎.