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crypto: handle exceptions in hmac/hash.digest #12164

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crypto: handle exceptions in hmac/hash.digest #12164

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768c986
crypto: handle exceptions in hmac/hash.digest
tniessen Apr 2, 2017
23b71f5
Disallow symbols as encoding
tniessen Apr 3, 2017
23f95ab
Add checks and regression test
tniessen Apr 3, 2017
27d359c
Punctuate commit in crypto.js
tniessen Apr 5, 2017
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3 changes: 2 additions & 1 deletion lib/crypto.js
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,8 @@ Hash.prototype.update = function update(data, encoding) {

Hash.prototype.digest = function digest(outputEncoding) {
outputEncoding = outputEncoding || exports.DEFAULT_ENCODING;
return this._handle.digest(outputEncoding);
// Explicit conversion for backward compatibility
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Femto-nit: can you punctuate the comment?

return this._handle.digest(`${outputEncoding}`);
};


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2 changes: 2 additions & 0 deletions src/node.cc
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Expand Up @@ -1481,6 +1481,8 @@ enum encoding ParseEncoding(const char* encoding,
enum encoding ParseEncoding(Isolate* isolate,
Local<Value> encoding_v,
enum encoding default_encoding) {
CHECK(!encoding_v.IsEmpty());

if (!encoding_v->IsString())
return default_encoding;

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20 changes: 7 additions & 13 deletions src/node_crypto.cc
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Expand Up @@ -3797,9 +3797,8 @@ void Hmac::HmacDigest(const FunctionCallbackInfo<Value>& args) {

enum encoding encoding = BUFFER;
if (args.Length() >= 1) {
encoding = ParseEncoding(env->isolate(),
args[0]->ToString(env->isolate()),
BUFFER);
CHECK(args[0]->IsString());
encoding = ParseEncoding(env->isolate(), args[0], BUFFER);
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Maybe leave a CHECK(args[i]->IsString()); line before the ParseEncoding calls?

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If I remember correctly, most functions just ignore invalid encoding values and use the default value instead. Currently, we are forcing the conversion to a string, but just because it is a string doesn't make it a valid encoding value. Adding a CHECK shouldn't do any harm, until we decide to finally drop support for toString() for consistency with other APIs. However, if we do not add a chack and the parameter is not a string (which won't happen now, but might as soon as we decide to drop support for toString()), there won't be any problems, the value will be ignored (ParseEncoding will return instantly).

The above only applies to hmac and hash. For sign and verify, the encoding parameter seems to always be null, so the CHECK would fail, right?

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@tniessen Still, if we drop toString() support it’s easy to just drop the checks again. (Likewise, it would be good if you included the test you said you had prepared in this PR – it’s easy to change things later, but for now it’s best to test the current behaviour.)

The above only applies to hmac and hash. For sign and verify, the encoding parameter seems to always be null, so the CHECK would fail, right?

It looks that way, yes… maybe you could fix that up and drop the unused code bits? That also simplifies SignFinal(), right now the StringBytes::Encode() encode call there seems like a completely unnecessary extra copy operation.

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@addaleax You are right, I will add the CHECKs and add the regression test.

maybe you could fix that up and drop the unused code bits?

Is it okay to do that in a separate PR or will that create too much organizational overhead?

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Is it okay to do that in a separate PR or will that create too much organizational overhead?

That’s your call… you can also maintain multiple commits in a single PR, which may or may not be easier for you. :) I don’t think there are other open pull requests for this code that would generate merge conflicts, and everything we talked about (except maybe dropping toString() support) semver-patch.

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I will create a separate PR after this gets merged to avoid conflicts and keep it simple, thank you for your support :)

}

unsigned char* md_value = nullptr;
Expand Down Expand Up @@ -3921,9 +3920,8 @@ void Hash::HashDigest(const FunctionCallbackInfo<Value>& args) {

enum encoding encoding = BUFFER;
if (args.Length() >= 1) {
encoding = ParseEncoding(env->isolate(),
args[0]->ToString(env->isolate()),
BUFFER);
CHECK(args[0]->IsString());
encoding = ParseEncoding(env->isolate(), args[0], BUFFER);
}

unsigned char md_value[EVP_MAX_MD_SIZE];
Expand Down Expand Up @@ -4201,10 +4199,8 @@ void Sign::SignFinal(const FunctionCallbackInfo<Value>& args) {

unsigned int len = args.Length();
enum encoding encoding = BUFFER;
if (len >= 2 && args[1]->IsString()) {
encoding = ParseEncoding(env->isolate(),
args[1]->ToString(env->isolate()),
BUFFER);
if (len >= 2) {
encoding = ParseEncoding(env->isolate(), args[1], BUFFER);
}

node::Utf8Value passphrase(env->isolate(), args[2]);
Expand Down Expand Up @@ -4452,9 +4448,7 @@ void Verify::VerifyFinal(const FunctionCallbackInfo<Value>& args) {

enum encoding encoding = UTF8;
if (args.Length() >= 3) {
encoding = ParseEncoding(env->isolate(),
args[2]->ToString(env->isolate()),
UTF8);
encoding = ParseEncoding(env->isolate(), args[2], UTF8);
}

ssize_t hlen = StringBytes::Size(env->isolate(), args[1], encoding);
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24 changes: 24 additions & 0 deletions test/parallel/test-regress-GH-9819.js
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@@ -0,0 +1,24 @@
'use strict';
const common = require('../common');
const assert = require('assert');
const execFile = require('child_process').execFile;

if (!common.hasCrypto) {
common.skip('missing crypto');
return;
}

const setup = 'const enc = { toString: () => { throw new Error("xyz"); } };';

const scripts = [
'crypto.createHash("sha256").digest(enc)',
'crypto.createHmac("sha256", "msg").digest(enc)'
];
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Adding the code in a test/fixtures file would be a bit more readable.

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@tniessen tniessen Apr 3, 2017 •
edited
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Do you mean adding the code as a JSON file or do you mean a JS file which can then be executed within the spawned node process? We are talking about two lines of code here...

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Yes, the latter. I'm fine with this the way it is, I'd just generally prefer a fixture. Feel free to ignore tho :-)

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Mhhh I think I will keep it this way unless someone expresses a strong opposing opinion, but thank you for your feedback :)


scripts.forEach((script) => {
const node = process.execPath;
const code = setup + ';' + script;
execFile(node, [ '-e', code ], common.mustCall((err, stdout, stderr) => {
assert(stderr.includes('Error: xyz'), 'digest crashes');
}));
});