Rewrite X.509 policy tree logic.

This reimplements policy handling using a similar DAG structure as in The
main difference is that, being C, we don't have std::set or std::map
easily available. But the algorithm can be implemented purely with
sorted lists, while remaining subquadratic.

This implementation relies on two assumptions:

1. We do not return the policy tree. This was removed in

2. We do not return the final set of certificate policies. I.e.,
   certificate policy checking is only used for evaluating policy
   constraints and X509_V_FLAG_EXPLICIT_POLICY.

The second assumption is not very important. It mostly simplifies
has_explicit_policy slightly.

In addition, this new implementation removes the per-certificate policy
cache. Instead, we just process the policy extensions anew on
certificate verification. This avoids a mess of threading complexity,
including a race condition in the old logic. See for a
description of the race condition.

Change-Id: Ifba9037588ecff5eb6ed3c34c8bd7611f60013a6
Commit-Queue: David Benjamin <>
Reviewed-by: Bob Beck <>
16 files changed
tree: 335109944ebf6cab76fca10a3a1d6adc8c47458d
  1. .github/
  2. crypto/
  3. decrepit/
  4. fuzz/
  5. include/
  6. rust/
  7. ssl/
  8. third_party/
  9. tool/
  10. util/
  11. .clang-format
  12. .gitignore
  16. CMakeLists.txt
  17. codereview.settings
  20. go.mod
  21. go.sum
  24. OpenSSLConfig.cmake
  28. sources.cmake


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: