[all-commits] [llvm/llvm-project] 6db44e: [Linux] Add kernel.yama.ptrace_scope note when ptr...

[Jordan Rupprecht via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6db44e52ce474bbeb66042073a6e3c6c586f78a2
      https://github.com/llvm/llvm-project/commit/6db44e52ce474bbeb66042073a6e3c6c586f78a2
  Author: Jordan Rupprecht <rupprecht at google.com>
  Date:   2023-03-02 (Thu, 02 Mar 2023)

  Changed paths:
    M lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
    M lldb/source/Plugins/Process/Linux/Procfs.cpp
    M lldb/source/Plugins/Process/Linux/Procfs.h
    M lldb/unittests/Process/Linux/ProcfsTests.cpp

  Log Message:
  -----------
  [Linux] Add kernel.yama.ptrace_scope note when ptrace fails to attach.

A common reason for LLDB failing to attach to an already-running process on Linux is the Yama security module: https://www.kernel.org/doc/Documentation/security/Yama.txt. This patch adds an explaination and suggested fix when it detects that case happening.

This was previously proposed in D106226, but hasn't been updated in a while. The last request was to put the check in a target-specific location, which is the approach this patch takes. I believe Yama only exists on Linux, so it's put in that package.

This has no end-to-end test because I'm not sure how to set `ptrace_scope` in a test environment -- if there are suggestions on how to do that, I'd be happy to add it. (Also, setting it to `3` is comically irreversible). I tested this locally.

Reviewed By: DavidSpickett, labath

Differential Revision: https://reviews.llvm.org/D144904