Chrome 18+：如何通过内容安全政策允许内联脚本？ [英] Chrome 18+: How to allow inline scripting with a Content Security Policy?
问题描述
进一步调查
我还测试了将适用指令放在 meta 标签而不是清单。虽然控制台消息中显示的CSP确实包含了标记的内容，但它不会执行内嵌脚本（在Chrome 53中）。
新的背景。 html ：
<！DOCTYPE html>
< html>
< head>
< meta http-equiv =Content-Security-Policycontent =script-src'self''sha256-WOdSzz11 / 3cpqOdrm89LBL2UPwEU9EhbDtMy2OciEhs ='>
< / head>
< body>
< script> alert（'foo'）;< / script>
< / body>
< / html>
结果：
$ b
附录：生成哈希值
这里有两种生成方法哈希值：
- Python（将JS传递给stdin，将其传递到其他地方）：
$ b $ prebug =lang-python prettyprint-override> import hashlib
import base64
import sys
def散列：
散列= hashlib.sha256（s.encode（））。digest（）
编码= base64.b64encode（散列）
返回编码
contents = sys.stdin.read（）
print（hash（contents））
- 在JS中，使用 Stanford Javascript Crypto Library ：
var sjcl = require（'sjcl'）;
//为给定的字符串生成base64编码的SHA256。
函数散列（s）{
var hashed = sjcl.hash.sha256.hash（s）;
返回sjcl.codec.base64.fromBits（hashed）;
}
确保何时对整个包含脚本标记的内容（包括所有前导/尾随空白）。如果您希望将其融入到您的构建中，则可以使用 cheerio 等相关部分。一般来说，对于任何 html ，您都可以这样做： $ b
var $ = cheerio.load（html）;
var csp_hashes = $（'script'）
.map（（i，el）=> hash（$（el）.text（））
.toArray（）
.map（h =>`'sha256 - $ {h}'`）
.join（''）;
var content_security_policy =`script-src'self''unsafe-eval'$ {csp_hashes}; object-src'self'`;
这是 hash-csp ，一个用于生成哈希的gulp插件。
Chrome 18 Dev/Canary has just been released, and content_security_policy will be needed in the manifest for certain extensions.
I'm trying to get a CSP working for inline scripting, but I don't know if I'm doing something wrong or if this is a Chrome 18 bug.
manifest.json:
{
"name": "CSP Test",
"version": "1.0",
"manifest_version": 2,
"options_page": "test.html",
"content_security_policy": "default-src 'unsafe-inline'"
}
test.html:
<html><head>
<script type="text/javascript">
alert("hello");
</script>
</head></html>
In Chrome 18, this unpacked extension fails to load, displaying an error:
If I change 'unsafe-inline' to 'self', the extension loads fine, but alert() does not work, and the option page's console contains an error:
Refused to execute inline script because of Content-Security-Policy.
In Chrome 16, using 'unsafe-inline' lets the extension load fine and alert() works, too. However, in Chrome 16, replacing 'unsafe-inline' with 'foo' lets the extension load, but of course does not let alert() work, so perhaps Chrome 18 is stricter than 16, but...
Is default-src 'unsafe-inline' actually invalid, or is this a bug? What CSP value can I use to make alert() work in Chrome 18?
Based on the accepted answer below, inline scripts no longer work in extensions in Chrome 18. alert() will need to be placed in its own JavaScript file.
For recent versions of Chrome (46+) the current answer is no longer true. unsafe-inline still has no effect (in the manifest and in meta header tags), but per the documentation, you can use the technique described here to relax the restriction.
Hash usage for
<script>elementsThe
script-srcdirective lets developers whitelist a particular inline script by specifying its hash as an allowed source of script.Usage is straightforward. The server computes the hash of a particular script block’s contents, and includes the base64 encoding of that value in the
Content-Security-Policyheader:Content-Security-Policy: default-src 'self'; script-src 'self' https://example.com 'sha256-base64 encoded hash'
Example
Consider the following:
manifest.json:
{
"manifest_version": 2,
"name": "csp test",
"version": "1.0.0",
"minimum_chrome_version": "46",
"content_security_policy": "script-src 'self' 'sha256-WOdSzz11/3cpqOdrm89LBL2UPwEU9EhbDtMy2OciEhs='",
"background": {
"page": "background.html"
}
}
background.html:
<!DOCTYPE html>
<html>
<head></head>
<body>
<script>alert('foo');</script>
</body>
</html>
Result:
Further investigation
I also tested putting the applicable directive in a meta tag instead of the manifest. While the CSP indicated in the console message did include the content of the tag, it would not execute the inline script (in Chrome 53).
new background.html:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Security-Policy" content="script-src 'self' 'sha256-WOdSzz11/3cpqOdrm89LBL2UPwEU9EhbDtMy2OciEhs='">
</head>
<body>
<script>alert('foo');</script>
</body>
</html>
Result:
Appendix: Generating the hashes
Here are two methods for generating the hashes:
- Python (pass JS to stdin, pipe it somewhere else):
import hashlib
import base64
import sys
def hash(s):
hash = hashlib.sha256(s.encode()).digest()
encoded = base64.b64encode(hash)
return encoded
contents = sys.stdin.read()
print(hash(contents))
- In JS, using the Stanford Javascript Crypto Library:
var sjcl = require('sjcl');
// Generate base64-encoded SHA256 for given string.
function hash(s) {
var hashed = sjcl.hash.sha256.hash(s);
return sjcl.codec.base64.fromBits(hashed);
}
Make sure when hashing the inline scripts that the whole contents of the script tag are included (including all leading/trailing whitespace). If you want to incorporate this into your builds, you can use something like cheerio to get the relevant sections. Generically, for any html, you can do:
var $ = cheerio.load(html);
var csp_hashes = $('script')
.map((i, el) => hash($(el).text())
.toArray()
.map(h => `'sha256-${h}'`)
.join(' ');
var content_security_policy = `script-src 'self' 'unsafe-eval' ${csp_hashes}; object-src 'self'`;
This is the method used in hash-csp, a gulp plugin for generating hashes.
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