Document how to use in github actions

[mariocj89]

Users might get the following error in CI:

💀 Engine error: No such process 💀

The specified process cannot be traced. This could be because the tracer
has insufficient privileges (the required capability is CAP_SYS_PTRACE).
Unprivileged processes cannot trace processes that they cannot send signals
to or those running set-user-ID/set-group-ID programs, for security reasons.
Alternatively, the process may already be being traced.

If your uid matches the uid of the target process you want to analyze, you
can do one of the following to get 'ptrace' scope permissions:

* If you are running inside a Docker container, you need to make sure you
  start the container using the '--cap-add=SYS_PTRACE' or '--privileged'
  command line arguments. Notice that this may not be enough if you are not
  running as 'root' inside the Docker container as you may need to disable
  hardening (see next points).

* Try running again with elevated permissions by running 'sudo -E !!'.

* You can disable kernel hardening for the current session temporarily (until
  a reboot happens) by running 'echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope'.

Rather than waiting for them to get the error to notice it, document that when running in github actions they should have a step that runs echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope.

We can add this in a section of the README file.

[JoanFM]

I get this error also in my local machine without Github Actions.

The specified process cannot be traced. This could be because the tracer
has insufficient privileges (the required capability is CAP_SYS_PTRACE).
Unprivileged processes cannot trace processes that they cannot send signals
to or those running set-user-ID/set-group-ID programs, for security reasons.
Alternatively, the process may already be being traced.

If your uid matches the uid of the target process you want to analyze, you
can do one of the following to get 'ptrace' scope permissions:

* If you are running inside a Docker container, you need to make sure you
  start the container using the '--cap-add=SYS_PTRACE' or '--privileged'
  command line arguments. Notice that this may not be enough if you are not
  running as 'root' inside the Docker container as you may need to disable
  hardening (see next points).

* Try running again with elevated permissions by running 'sudo -E !!'.

* You can disable kernel hardening for the current session temporarily (until
  a reboot happens) by running 'echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope'.

[mariocj89]

You need indeed to do the step recommended on the error message:

• You can disable kernel hardening for the current session temporarily (until
  a reboot happens) by running 'echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope'.

See

pytest-pystack/.github/workflows/validate.yaml

Line 50 in 1e19e00

- name: Disable ptrace security restrictions

for an example