| commit | bdc35b63617f78037768f4897d8835696f02181a | [log] [tgz] |
|---|---|---|
| author | David Benjamin <davidben@google.com> | Tue Mar 01 18:11:51 2022 -0500 |
| committer | Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> | Tue Mar 08 17:28:24 2022 +0000 |
| tree | c2b03985b88b2cc471737349832b48aa4fc41747 | |
| parent | 366e8866285e66f25b85293c04cd548a355e7aa5 [diff] |
Rewrite and tighten ASN1_INTEGER encoding and decoding. This fixes several issues around ASN1_INTEGER handling. First, invalid INTEGERs (not allowed in BER or DER) will no longer be accepted by d2i_ASN1_INTEGER. This aligns with upstream OpenSSL, which became strict in 6c5b6cb035666d46495ccbe4a4f3d5e3a659cd40, part of OpenSSL 1.1.0. In addition to matching the standard, this is needed to avoid round-tripping issues: ASN1_INTEGER uses a sign-and-magnitude representation, different from the DER two's complement representation. That means we cannot represent invalid DER INTEGERs. Attempting to do so messes up some invariants and causes values to not round-trip correctly when re-encoded. Thanks to Tavis Ormandy for catching this. Next, this CL tidies the story around invalid ASN1_INTEGERs (non-minimal and negative zero). Although we will never produce them in parsing, it is still possible to manually construct them with ASN1_STRING APIs. Historically (CVE-2016-2108), it was possible to get them out of the parser, due to a different bug, *and* i2d_ASN1_INTEGER had a memory error in doing so. That different bug has since been fixed, but we should still handle them correctly and test this. (To that end, this CL adds a test we ought to have added importing upstream's 3661bb4e7934668bd99ca777ea8b30eedfafa871 back in c4eec0c16b02c97a62a95b6a08656c3a9ddb6baa.) As the two's complement invariants are subtle as it is, I've opted to just fix the invalid values before encoding. However, invalid ASN1_INTEGERs still do not quite work right because ASN1_INTEGER_get, ASN1_INTEGER_cmp, and ASN1_STRING_cmp will all return surprising values with them. I've left those alone. Finally, that leads to the zero value. Almost every function believes the representation of 0 is a "\0" rather than "". However, a default-constructed INTEGER, like any other string type, is "". Those do not compare as equal. crypto/asn1 treats ASN1_INTEGER generically as ASN1_STRING enough that I think changing the other functions to match is cleaner than changing default-constructed ASN1_INTEGERs. Thus this CL removes all the special cases around zero. Update-Note: Invalid INTEGERs will no longer parse, but they already would not have parsed in OpenSSL. Additionally, zero is now internally represented as "" rather than "\0". Bug: 354 Change-Id: Id4d51a18f32afe90fd4df7455b21e0c8bdbc5389 Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/51632 Reviewed-by: Adam Langley <agl@google.com> Commit-Queue: David Benjamin <davidben@google.com>
BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.
Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.
Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.
BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.
Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.
Project links:
There are other files in this directory which might be helpful: