| commit | 53b876a4d15da0145495ec3a17521a2690fe5978 | [log] [tgz] |
|---|---|---|
| author | David Benjamin <davidben@google.com> | Wed Feb 01 23:40:18 2023 -0500 |
| committer | Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> | Fri Feb 03 17:07:57 2023 +0000 |
| tree | c8f44a268183079b75f457343a28212a954fa6af | |
| parent | aa83c12069f3d62704fce3d499b068b5bf1b6e31 [diff] |
Stop clang from un-constant-timing copy_from_prebuf. Newer versions of clang figure out that copy_from_prebuf (used in builds that aren't x86_64 with assembly optimizations) has a bunch of no-op iterations and insert a branch. Add a value barrier to stop it. This was caught by our valgrind-based constant-time validation. As part of this, I noticed that OPENSSL_NO_ASM builds turn off value barriers. This is because the value barriers use an empty inline asm block. While this is technically correct, it's probably unnecessary. The clang|gcc check means we know GCC-style inline assembly is supported. Disabling inline asm is used by sanitizers to shut off unintrumentable code, but there's no uninstrumentable code in the empty string. It's also used by consumers who haven't figured out how to integrate an assembler into their build system, but that also doesn't apply. So just remove the condition on the value barriers so OPENSSL_NO_ASM also get mitigations. Update-Note: It is possible the above is wrong and some OPENSSL_NO_ASM relied on value barriers being disabled. If so, this will break that build and we'll need to reconsider. Change-Id: I6e3ea3ee705bef3afcf42d3532b17aaabbbcc60b Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/56827 Reviewed-by: Bob Beck <bbe@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: