Add .note.GNU-stack at the source level.

GNU-based toolchains on ELF platforms default the stack to executable
and rely on a .note.GNU-stack section in *each* object file to flip it
off. The compiler knows to do this for its object files, but assembly
does everything by hand. See this link for details:
https://www.airs.com/blog/archives/518

We do this in the cmake build by passing -Wa,--noexecstack to the
assembler. However, since we have to deal with many buildsystems, it
would be more robust to put it in the source.

It's unclear whether this should be gated on ELF or Linux. The Gentoo
and Ubuntu documents recommend checking for Linux with gas, but only ELF
with NASM.
https://wiki.gentoo.org/wiki/Hardened/GNU_stack_quickstart
https://wiki.ubuntu.com/SecurityTeam/Roadmap/ExecutableStacks

At the same time, these links suggest it is an ELF-wide issue and not
just Linux:
https://github.com/golang/go/issues/5392
https://reviews.freebsd.org/D11033

https://github.com/openssl/openssl/issues/4575 also discusses this but
the rationale lists both ELF and non-ELF platforms, so it's unclear.

Treat it as ELF-wide for now. We can revisit this if necessary.

Update-Note: If there is a build failure due to .note.GNU-stack, holler.
Change-Id: Ic59096aa1fc2bf5380a412c9991de22cb46c0faf
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/37984
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
7 files changed
tree: 625eb03be33ca430f83338411793db54ee5dfba5
  1. .clang-format
  2. .github/
  3. .gitignore
  4. API-CONVENTIONS.md
  5. BREAKING-CHANGES.md
  6. BUILDING.md
  7. CMakeLists.txt
  8. CONTRIBUTING.md
  9. FUZZING.md
  10. INCORPORATING.md
  11. LICENSE
  12. PORTING.md
  13. README.md
  14. STYLE.md
  15. codereview.settings
  16. crypto/
  17. decrepit/
  18. fuzz/
  19. go.mod
  20. include/
  21. sources.cmake
  22. ssl/
  23. third_party/
  24. tool/
  25. util/
README.md

BoringSSL

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: