crypto: handle OpenSSL error queue in CipherBase by tniessen · Pull Request #21288 · nodejs/node

tniessen · 2018-06-12T14:30:19Z

This handles all errors produced by OpenSSL within the CipherBase class. API functions clear the error queue on return, utility functions such as InitAuthenticated() ensure that they do not add any new errors to the queue. Previously ignored return values are now being CHECK'd.

::Final does not clear the error queue as there is a custom error handler in place.

Note that #21287 is required for this to work, otherwise the CHECK in line 2597 will fail.

Fixes: #21281

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
commit message follows commit guidelines

This handles all errors produced by OpenSSL within the CipherBase class. API functions clear the error queue on return, utility functions such as InitAuthenticated() ensure that they do not add any new errors to the queue. Previously ignored return values are now being CHECK'd. Fixes: nodejs#21281 Refs: nodejs#21287

nodejs-github-bot · 2018-06-12T14:30:21Z

@tniessen sadly an error occured when I tried to trigger a build :(

tniessen · 2018-06-12T19:39:58Z

cc @nodejs/crypto

addaleax · 2018-06-14T11:41:47Z

 bool CipherBase::InitAuthenticated(const char* cipher_type, int iv_len,
 unsigned int auth_tag_len) {
 CHECK(IsAuthenticatedMode());
+ MarkPopErrorOnReturn mark_pop_error_on_return;


For my own understanding: MarkPopErrorOnReturn basically means that OpenSSL errors inside this scope are swallowed/ignored?

Exactly, all errors that occur in this scope are dropped once the destructor is called (unless they have been handled specifically).

And now that we're handling the errors manually, Node will be throwing an error instead of just crashing, I suppose?

And because we're manually handling the errors now, it's better because we'll throw an error that you could catch and what not instead of just crashing, right?

It won't throw more errors than before (except for ::Init), it will just make sure that if it throws, it also clears the internal error queue of OpenSSL.

addaleax · 2018-06-14T11:46:04Z

Travis CI failure looks related:


not ok 346 parallel/test-crypto-binary-default
---
duration_ms: 0.418
severity: crashed
exitcode: -6
stack: |-
out/Release/node[60848]: ../src/node_crypto.cc:2598:void node::crypto::CipherBase::Init(const char *, const char *, int, unsigned int): Assertion `EVP_CipherInit_ex(ctx_.get(), cipher, nullptr, nullptr, nullptr, encrypt)' failed.
1: node::Abort() [out/Release/node]
2: 0x815a7d [out/Release/node]
3: node::crypto::CipherBase::Init(char const*, char const*, int, unsigned int) [out/Release/node]
4: node::crypto::CipherBase::Init(v8::FunctionCallbackInfo<v8::Value> const&) [out/Release/node]
5: v8::internal::FunctionCallbackArguments::Call(v8::internal::CallHandlerInfo*) [out/Release/node]
6: 0xa39f4f [out/Release/node]
7: 0xa39616 [out/Release/node]
8: 0x2be3fc7041bd
...

tniessen · 2018-06-14T11:52:49Z

@addaleax Yes, see above:

Note that #21287 is required for this to work, otherwise the CHECK in line 2597 will fail.

As far as I can tell, #15037 should have set the flag before calling EVP_CipherInit_Ex, otherwise, the call will fail in some modes. We never noticed because we didn't perform proper error-checking and OpenSSL left the context in a partially initialized state which was enough for the rest of the API to work. This PR adds a CHECK to ensure that the initialization actually succeeds from OpenSSL's perspective.

bnoordhuis · 2018-06-14T12:43:02Z

 ctx_.reset(EVP_CIPHER_CTX_new());
 const bool encrypt = (kind_ == kCipher);
- EVP_CipherInit_ex(ctx_.get(), cipher, nullptr, nullptr, nullptr, encrypt);
+ CHECK(EVP_CipherInit_ex(ctx_.get(), cipher, nullptr,


EVP_CipherInit_ex() can fail for legitimate reasons (e.g. an engine that fails to load) so a CHECK is not appropriate.

I assume the old behavior (= no error checking) isn't appropriate either?

Indeed, errors should be reported.

That would make this semver-major I guess, so I'll probably just leave the CHECKs out for now.

Mwah, I don't think better error checking constitutes semver-major. The kind of bugs it'd flush out are programmer bugs and environmental issues.

bnoordhuis · 2018-06-14T12:44:37Z

 bool CipherBase::SetAAD(const char* data, unsigned int len, int plaintext_len) {
 if (!ctx_ || !IsAuthenticatedMode())
 return false;
+ ClearErrorOnReturn clear_error_on_return;


This should ideally be MarkPopErrorOnReturn. ClearErrorOnReturn is a blunt hammer and might swallow genuine errors.

Point taken, I can change it. In practice, the error stack should be empty when the JS layer calls into the C++ layer though, right?

Yes, except for the following:
It can mess up C++ -> C++ calls when the caller also manipulates the error stack.
I know of at least one add-on that leaves openssl errors on the stack for some time.

Instead of clearing all errors, mark and pop only errors that were added within the current scope.

tniessen · 2018-07-01T11:36:07Z

@bnoordhuis Please take another look.

ryzokuken

Unrelated, but node_crypto.cc seems to have become rather long, don't you think? Do you believe we should try break it into smaller parts (and even namespaces) at this point?

ryzokuken · 2018-07-01T18:20:09Z

 ctx_.reset(EVP_CIPHER_CTX_new());
 const bool encrypt = (kind_ == kCipher);
- EVP_CipherInit_ex(ctx_.get(), cipher, nullptr, nullptr, nullptr, encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(), cipher, nullptr,


Style nit, but shouldn't this be done the other way around? Eg: EVP_CipherInit_ex(...) != 1? Would love to hear why you chose this over the former.

Didn't know we had a preference. I usually do the opposite, but I think having != 1 at the end of a multi-line expression looks weird.
Fun fact, this style was commonly used to prevent accidental assignment of variables / pointers in boolean expressions.

Because people would accidentally type = instead of == all the times? Sounds more likely in the era of butterfly keyboards, heh. If it makes sense for you to keep this, feel free to do so. I agree wholeheartedly that != 1 looks weird when in a multiline statement, just wanted to make sure we're not going against the style guide here.

Yes, even though I personally still prefer var == constant, the only reason here is that it looks weird. If no one has a strong opinion against this, I'd prefer to keep it this way.

ryzokuken · 2018-07-01T18:20:38Z

- reinterpret_cast<unsigned char*>(key),
- reinterpret_cast<unsigned char*>(iv),
- encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(),


Same as above.

ryzokuken · 2018-07-01T18:20:54Z


 const bool encrypt = (kind_ == kCipher);
- EVP_CipherInit_ex(ctx_.get(), cipher, nullptr, nullptr, nullptr, encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(), cipher, nullptr,


ryzokuken · 2018-07-01T18:21:16Z

- reinterpret_cast<const unsigned char*>(key),
- reinterpret_cast<const unsigned char*>(iv),
- encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(),


This is getting boring, isn't it? 😛

ryzokuken · 2018-07-01T18:21:58Z

 bool CipherBase::InitAuthenticated(const char* cipher_type, int iv_len,
 unsigned int auth_tag_len) {
 CHECK(IsAuthenticatedMode());
+ MarkPopErrorOnReturn mark_pop_error_on_return;


And now that we're handling the errors manually, Node will be throwing an error instead of just crashing, I suppose?

ryzokuken · 2018-07-01T18:27:15Z

- reinterpret_cast<unsigned char*>(key),
- reinterpret_cast<unsigned char*>(iv),
- encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(),


Same as above.

ryzokuken · 2018-07-01T18:27:27Z


 const bool encrypt = (kind_ == kCipher);
- EVP_CipherInit_ex(ctx_.get(), cipher, nullptr, nullptr, nullptr, encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(), cipher, nullptr,


Same as above.

ryzokuken · 2018-07-01T18:27:44Z

- reinterpret_cast<const unsigned char*>(key),
- reinterpret_cast<const unsigned char*>(iv),
- encrypt);
+ if (1 != EVP_CipherInit_ex(ctx_.get(),


God, isn't this repetitive 😅

ryzokuken · 2018-07-01T18:28:30Z

 bool CipherBase::InitAuthenticated(const char* cipher_type, int iv_len,
 unsigned int auth_tag_len) {
 CHECK(IsAuthenticatedMode());
+ MarkPopErrorOnReturn mark_pop_error_on_return;


And because we're manually handling the errors now, it's better because we'll throw an error that you could catch and what not instead of just crashing, right?

ryzokuken · 2018-07-01T18:32:10Z

- EVP_CTRL_GCM_SET_TAG,
- auth_tag_len_,
- reinterpret_cast<unsigned char*>(auth_tag_));
+CHECK(EVP_CIPHER_CTX_ctrl(ctx_.get(),


I'm a bit intrigued.
https://www.openssl.org/docs/man1.0.2/crypto/EVP_EncryptInit.html doesn't show EVP_CIPHER_CTX_ctrl returning anything. If it's actually returning void (I hope not), the would this work?
If it doesn't return void, shouldn't we use an if statement here as well and throw something nice instead of crashing the process?

The only reasons I can think of right now are a bug (e.g. because we permitted the call in an invalid state) or a memory allocation failure, and those are generally not handled within our APIs.

ryzokuken

LGTM

tniessen · 2018-07-07T13:41:27Z

CI: https://ci.nodejs.org/job/node-test-pull-request/15753/

Pinging @nodejs/crypto one last time.

tniessen · 2018-07-12T14:02:44Z

Landed in 85b0f16.

This handles all errors produced by OpenSSL within the CipherBase class. API functions ensure that they do not add any new errors to the error queue. Also adds a couple of CHECKs and throws under certain conditions. PR-URL: #21288Fixes: #21281 Refs: #21287 Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>

Squashed commit of the following: commit a61cace46f4f745283177a6ca4551e6237aa4d8a Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 15:33:19 2020 +0200 Downgrade eslint to version 6.8.0 Version 7 dropped support for node 8 commit f08aa1e125738fe00183306f925d4e2ecf9e5704 Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 14:52:18 2020 +0200 FIX unit tests - Made environment.js work with the newer mocha version - Remove all Buffer constructors - Change test order to fix broken tests in node < 10.7 - nodejs/node#21288 - Changed minimum node version to 8, due to the updated dependencies commit ce1f40d4e5ae79f4bcf6a3cca0f914ef51effd3b Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 14:52:04 2020 +0200 Relint jwt-utils.js with newer eslint rules commit 59940f5552dbfb8353e71250b1a0d3038913a17e Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 14:50:51 2020 +0200 Replace new Buffer with Buffer.from and Buffer.alloc The Buffer constructor was deprecated: https://nodejs.org/en/docs/guides/buffer-constructor-deprecation/ commit b46245788a6235b0490f9902e9218945cb6d585c Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 14:48:56 2020 +0200 Remove travis and coveralls badges Also removed the .travis file and npm script. Neither service is executing their pipelines for this repo anymore commit 23f537ad6fdc4b8924add6feb16628512529a47a Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 14:48:42 2020 +0200 Integrate jscsrc rules into eslintrc commit c0e23b53a27d82d14430d05b63426dcae868cfd9 Author: Hugo Ferrando Seage <hugoseage@gmail.com> Date: Wed May 13 14:44:52 2020 +0200 CHORE update dependencies - coveralls removed as the pipeline is not executed anymore - jscs removed as it was deprecated - added eslint-google dependency to replace jscs with eslint - jwa NOT updated as it would break compatibility - therror NOT updated

nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. crypto Issues and PRs related to the crypto subsystem. labels Jun 12, 2018

tniessen mentioned this pull request Jun 12, 2018
Calling crypto.createCipheriv with a key of invalid length can cause errors in other consumers of the OpenSSL error queue #21281
Closed

tniessen requested review from bnoordhuis and ryzokuken June 12, 2018 16:10

addaleax reviewed Jun 14, 2018
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bnoordhuis reviewed Jun 14, 2018
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tniessen added 2 commits June 14, 2018 17:46

Don't clear all errors in return
0a89f42
Instead of clearing all errors, mark and pop only errors that were added within the current scope.

Add error checking for EVP_CipherInit_ex
2fda8de

ryzokuken reviewed Jul 1, 2018
View reviewed changes

ryzokuken approved these changes Jul 1, 2018
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tniessen mentioned this pull request Jul 2, 2018
Proposal: Splitting up node_crypto.cc #16524
Closed

tniessen closed this Jul 12, 2018

targos mentioned this pull request Jul 17, 2018
v10.7.0 proposal #21851
Merged

hugo19941994 mentioned this pull request Oct 22, 2018
Tests fail with Node.js >= 4 Telefonica/node-jwt-utils#12
Closed

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tniessen commented Jun 12, 2018

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addaleax commented Jun 14, 2018

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tniessenJun 14, 2018•
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