├── .gitignore ├── LICENSE ├── README.md ├── go.mod ├── secfetch.go └── secfetch_test.go /.gitignore: -------------------------------------------------------------------------------- 1 | # Binaries for programs and plugins 2 | *.exe 3 | *.exe~ 4 | *.dll 5 | *.so 6 | *.dylib 7 | 8 | # Test binary, build with `go test -c` 9 | *.test 10 | 11 | # Output of the go coverage tool, specifically when used with LiteIDE 12 | *.out 13 | 14 | # Ctags 15 | tags 16 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # secfetch 2 | [![License](https://img.shields.io/badge/license-Apache--2.0-blue.svg)](https://raw.githubusercontent.com/empijei/go-sec-fetch/master/LICENSE) 3 | [![Coverage](https://img.shields.io/badge/coverage-100%25-brightgreen.svg)](#) 4 | [![Go Report Card](https://goreportcard.com/badge/github.com/empijei/go-sec-fetch)](https://goreportcard.com/report/github.com/empijei/go-sec-fetch) 5 | 6 | [Fetch Metadata](https://w3c.github.io/webappsec-fetch-metadata/) server security middleware for Go. 7 | 8 | See docs on [godoc.org](https://godoc.org/github.com/empijei/go-sec-fetch). 9 | -------------------------------------------------------------------------------- /go.mod: -------------------------------------------------------------------------------- 1 | module github.com/empijei/go-sec-fetch 2 | 3 | go 1.12 4 | -------------------------------------------------------------------------------- /secfetch.go: -------------------------------------------------------------------------------- 1 | // Copyright 2019 Google LLC 2 | // 3 | // Licensed under the Apache License, Version 2.0 (the "License"); 4 | // you may not use this file except in compliance with the License. 5 | // You may obtain a copy of the License at 6 | // 7 | // https://www.apache.org/licenses/LICENSE-2.0 8 | // 9 | // Unless required by applicable law or agreed to in writing, software 10 | // distributed under the License is distributed on an "AS IS" BASIS, 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 | // See the License for the specific language governing permissions and 13 | // limitations under the License. 14 | 15 | // Package secfetch implements a simple middleware to protect HTTP handlers from cross-origin 16 | // requests by leveraging Fetch Metadata. 17 | // 18 | // Suggested usage is to protect the entire http.Server.Handler and not single handlers. 19 | // Example usage: 20 | // srv := http.Server{ 21 | // Handler: secfetch.ProtectHandler(myServeMux), 22 | // // Rest of configuration here. 23 | // } 24 | // 25 | // This package supports a log-only mode to ease deployment and test the configuration before enforcing it. 26 | // 27 | // It is possible to exempt some handlers by registering them on a http.ServeMux after a previous 28 | // one has been protected. A use case for this is CORS APIs that need to reply to cross-site 29 | // requests. 30 | // Example: 31 | // var pmux http.ServeMux 32 | // pmux.Handle("/protected1", protHandler1) 33 | // pmux.Handle("/protected2", protHandler2) 34 | // var mux http.ServeMux 35 | // mux.Handle("/", secfetch.ProtectHandler(&pmux)) 36 | // mux.Handle("/unprotected", publicHandler) 37 | package secfetch 38 | 39 | import ( 40 | "fmt" 41 | "net/http" 42 | ) 43 | 44 | func allowed(r *http.Request) bool { 45 | site := r.Header.Get("sec-fetch-site") 46 | mode := r.Header.Get("sec-fetch-mode") 47 | 48 | // This allows same-site requests. 49 | // To harden this protection uncomment the second condition. 50 | if site != "cross-site" /*&& site != "same-site"*/ { 51 | return true 52 | } 53 | 54 | // https://github.com/w3c/webappsec-fetch-metadata/issues/35 55 | // https://bugs.chromium.org/p/chromium/issues/detail?id=979946 56 | if mode == "" && r.Method == http.MethodOptions { 57 | return true 58 | } 59 | 60 | // Here site is "cross-site", so let's just allow non-state-changing navigations 61 | if (mode == "navigate" || mode == "nested-navigate") && 62 | (r.Method == http.MethodGet || r.Method == http.MethodHead) { 63 | return true 64 | } 65 | 66 | // Cross-site potentially dangerous request, reject. 67 | return false 68 | } 69 | 70 | // ProtectHandler isolates h from potentially malicious requests. 71 | func ProtectHandler(h http.Handler) http.Handler { 72 | return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 73 | if !allowed(r) { 74 | w.WriteHeader(http.StatusForbidden) 75 | fmt.Fprintln(w, "Invalid resource access") 76 | return 77 | } 78 | h.ServeHTTP(w, r) 79 | }) 80 | } 81 | 82 | // RequestLogger is a type that can log http requests. 83 | type RequestLogger interface { 84 | // LogRequest is called with every request that needs to be logged. 85 | LogRequest(*http.Request) 86 | } 87 | 88 | // ProtectHandlerLogOnly behaves like ProtectHandler, but only logs requests that would have been 89 | // blocked. 90 | func ProtectHandlerLogOnly(h http.Handler, rl RequestLogger) http.Handler { 91 | return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 92 | if !allowed(r) { 93 | rl.LogRequest(r) 94 | } 95 | h.ServeHTTP(w, r) 96 | }) 97 | } 98 | -------------------------------------------------------------------------------- /secfetch_test.go: -------------------------------------------------------------------------------- 1 | // Copyright 2019 Google LLC 2 | // 3 | // Licensed under the Apache License, Version 2.0 (the "License"); 4 | // you may not use this file except in compliance with the License. 5 | // You may obtain a copy of the License at 6 | // 7 | // https://www.apache.org/licenses/LICENSE-2.0 8 | // 9 | // Unless required by applicable law or agreed to in writing, software 10 | // distributed under the License is distributed on an "AS IS" BASIS, 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 | // See the License for the specific language governing permissions and 13 | // limitations under the License. 14 | 15 | package secfetch 16 | 17 | import ( 18 | "bytes" 19 | "fmt" 20 | "net/http" 21 | "net/http/httptest" 22 | "strings" 23 | "testing" 24 | ) 25 | 26 | var checkTests = []struct { 27 | name, site, mode, method string 28 | want bool 29 | }{ 30 | { 31 | name: "no headers", 32 | site: "", 33 | mode: "", 34 | method: "POST", 35 | want: true, 36 | }, 37 | { 38 | name: "ua initiated", 39 | site: "none", 40 | mode: "", 41 | method: "GET", 42 | want: true, 43 | }, 44 | { 45 | name: "cors bug missing mode", 46 | site: "cross-site", 47 | mode: "", 48 | method: "OPTIONS", 49 | want: true, 50 | }, 51 | { 52 | name: "same site", 53 | site: "same-site", 54 | mode: "websocket", 55 | method: "HEAD", 56 | want: true, 57 | }, 58 | { 59 | name: "same origin", 60 | site: "same-origin", 61 | mode: "unrecognized", 62 | method: "POST", 63 | want: true, 64 | }, 65 | { 66 | name: "cross origin nested navigate", 67 | site: "cross-site", 68 | mode: "nested-navigate", 69 | method: "GET", 70 | want: true, 71 | }, 72 | { 73 | name: "cross origin head navigate", 74 | site: "cross-site", 75 | mode: "navigate", 76 | method: "HEAD", 77 | want: true, 78 | }, 79 | { 80 | name: "cross origin navigate", 81 | site: "cross-site", 82 | mode: "navigate", 83 | method: "GET", 84 | want: true, 85 | }, 86 | { 87 | name: "cross origin form submission", 88 | site: "cross-site", 89 | mode: "navigate", 90 | method: "POST", 91 | want: false, 92 | }, 93 | { 94 | name: "cross origin no cors", 95 | site: "cross-site", 96 | mode: "no-cors", 97 | method: "GET", 98 | want: false, 99 | }, 100 | { 101 | name: "cross origin cors", 102 | site: "cross-site", 103 | mode: "cors", 104 | method: "POST", 105 | want: false, 106 | }, 107 | } 108 | 109 | func TestProtectHandler(t *testing.T) { 110 | const data = "User Data" 111 | hf := ProtectHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 112 | fmt.Fprintf(w, data) 113 | })) 114 | for _, tt := range checkTests { 115 | t.Run(tt.name, func(t *testing.T) { 116 | var r *http.Request 117 | if tt.method == "POST" { 118 | r = httptest.NewRequest(tt.method, "/", strings.NewReader("body")) 119 | } else { 120 | r = httptest.NewRequest(tt.method, "/", nil) 121 | } 122 | r.Header.Set("sec-fetch-site", tt.site) 123 | r.Header.Set("sec-fetch-mode", tt.mode) 124 | w := httptest.NewRecorder() 125 | hf.ServeHTTP(w, r) 126 | if w.Code != 200 && bytes.Contains(w.Body.Bytes(), []byte(data)) { 127 | t.Errorf("Status was set but user data leaked anyways") 128 | } 129 | if got := w.Code == 200; got != tt.want { 130 | t.Errorf("(%q,%q,%q): got %v, want %v", tt.method, tt.site, tt.mode, got, tt.want) 131 | } 132 | }) 133 | } 134 | } 135 | 136 | type testRequestLogger struct { 137 | rs []*http.Request 138 | } 139 | 140 | func (t *testRequestLogger) LogRequest(r *http.Request) { 141 | t.rs = append(t.rs, r) 142 | } 143 | 144 | func (t *testRequestLogger) reset() { 145 | var rs []*http.Request 146 | t.rs = rs 147 | } 148 | 149 | func TestProtectHandlerLogOnly(t *testing.T) { 150 | const data = "User Data" 151 | var tl testRequestLogger 152 | hf := ProtectHandlerLogOnly(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 153 | fmt.Fprintf(w, data) 154 | }), &tl) 155 | for _, tt := range checkTests { 156 | t.Run(tt.name, func(t *testing.T) { 157 | var r *http.Request 158 | defer tl.reset() 159 | if tt.method == "POST" { 160 | r = httptest.NewRequest(tt.method, "/", strings.NewReader("body")) 161 | } else { 162 | r = httptest.NewRequest(tt.method, "/", nil) 163 | } 164 | r.Header.Set("sec-fetch-site", tt.site) 165 | r.Header.Set("sec-fetch-mode", tt.mode) 166 | w := httptest.NewRecorder() 167 | hf.ServeHTTP(w, r) 168 | if w.Code != 200 { 169 | t.Errorf("Status was set in log only mode") 170 | } 171 | if !bytes.Contains(w.Body.Bytes(), []byte(data)) { 172 | t.Errorf("Response body was changed in log only mode") 173 | } 174 | if got := len(tl.rs) == 0; got != tt.want { 175 | t.Errorf("(%q,%q,%q): got %v, want %v", tt.method, tt.site, tt.mode, got, tt.want) 176 | } 177 | }) 178 | } 179 | } 180 | 181 | func TestExempt(t *testing.T) { 182 | const private = "User Data" 183 | const public = "Public Data" 184 | var pmux http.ServeMux 185 | pmux.Handle("/protected", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 186 | fmt.Fprintf(w, private) 187 | })) 188 | var mux http.ServeMux 189 | mux.Handle("/", ProtectHandler(&pmux)) 190 | mux.Handle("/unprotected", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { 191 | fmt.Fprintf(w, public) 192 | })) 193 | 194 | type pathTest struct { 195 | name, site, mode, method, path string 196 | want bool 197 | } 198 | var tests []pathTest 199 | for _, tt := range checkTests { 200 | tests = append(tests, pathTest{ 201 | name: "protected " + tt.name, 202 | site: tt.site, 203 | mode: tt.mode, 204 | method: tt.method, 205 | path: "/protected", 206 | want: tt.want, 207 | }) 208 | } 209 | for _, tt := range checkTests { 210 | tests = append(tests, pathTest{ 211 | name: "unprotected " + tt.name, 212 | site: tt.site, 213 | mode: tt.mode, 214 | method: tt.method, 215 | path: "/unprotected", 216 | want: true, 217 | }) 218 | } 219 | 220 | for _, tt := range tests { 221 | t.Run(tt.name, func(t *testing.T) { 222 | var r *http.Request 223 | if tt.method == "POST" { 224 | r = httptest.NewRequest(tt.method, tt.path, strings.NewReader("body")) 225 | } else { 226 | r = httptest.NewRequest(tt.method, tt.path, nil) 227 | } 228 | r.Header.Set("sec-fetch-site", tt.site) 229 | r.Header.Set("sec-fetch-mode", tt.mode) 230 | w := httptest.NewRecorder() 231 | mux.ServeHTTP(w, r) 232 | if w.Code != 200 && bytes.Contains(w.Body.Bytes(), []byte(private)) { 233 | t.Errorf("Status was set but user data leaked anyways") 234 | } 235 | if got := w.Code == 200; got != tt.want { 236 | t.Errorf("(%q,%q,%q,%q): got %v, want %v", tt.method, tt.path, tt.site, tt.mode, got, tt.want) 237 | } 238 | }) 239 | } 240 | } 241 | --------------------------------------------------------------------------------