[PATCH v4 2/4] Introduce seccomp-assisted syscall filtering

[Dmitry V. Levin]

On Thu, Aug 29, 2019 at 04:00:24PM +0200, Paul Chaignon wrote:
[...]
> +		if (seccomp_filtering) {
> +			/*
> +			 * Syscall and seccomp stops can happen in different
> +			 * orders depending on kernel.  strace tests this in
> +			 * check_seccomp_order_tracer().
> +			 *
> +			 * Linux 3.5--4.7:
> +			 * (seccomp-stop before syscall-entry-stop)
> +			 *         +--> seccomp-stop ->-PTRACE_SYSCALL->-+
> +			 *         |                                     |
> +			 *     PTRACE_CONT                   syscall-entry-stop
> +			 *         |                                     |
> +			 * syscall-exit-stop <---PTRACE_SYSCALL-----<----+
> +			 *
> +			 * Linux 4.8+:
> +			 * (seccomp-stop after syscall-entry-stop)
> +			 *                 syscall-entry-stop
> +			 * 
> +			 *         +---->-----PTRACE_CONT---->----+
> +			 *         |                              |
> +			 *  syscall-exit-stop               seccomp-stop
> +			 *         |                              |
> +			 *         +----<----PTRACE_SYSCALL---<---+
> +			 *
> +			 * Note in Linux 4.8+, we restart in PTRACE_CONT after
> +			 * syscall-exit to skip the syscall-entry-stop.  The
> +			 * next seccomp-stop will be treated as a syscall
> +			 * entry.
> +			 * 
> +			 * The below line implements this behavior. Note
> +			 * exiting(current_tcp) actually marks a
> +			 * syscall-entry-stop because the flag was inverted in
> +			 * the above call to trace_syscall.
> +			 */

I like ASCII graphics, but it contains trailing whitespaces rejected
by my pre-commit hook.

Try "git config --global apply.whitespace error-all".


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