linux-kernel - Re: [PATCH] seccomp: passthrough uretprobe systemcall without filtering

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Message-ID: <20250121164435.GA17215@redhat.com>
Date: Tue, 21 Jan 2025 17:44:35 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Jiri Olsa <olsajiri@...il.com>, Eyal Birger <eyal.birger@...il.com>,
	Kees Cook <kees@...nel.org>, luto@...capital.net, wad@...omium.org,
	ldv@...ace.io, mhiramat@...nel.org, andrii@...nel.org,
	alexei.starovoitov@...il.com, cyphar@...har.com,
	songliubraving@...com, yhs@...com, john.fastabend@...il.com,
	peterz@...radead.org, tglx@...utronix.de, bp@...en8.de,
	daniel@...earbox.net, ast@...nel.org, andrii.nakryiko@...il.com,
	rafi@....io, shmulik.ladkani@...il.com, bpf@...r.kernel.org,
	linux-api@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] seccomp: passthrough uretprobe systemcall without
 filtering

On 01/21, Steven Rostedt wrote:
>
> I think this may have been mentioned, but is there a way that the kernel
> could know that this system call is being monitored by seccomp, and if so,
> just stick with the interrupt version? If not, enable the system call?

Consider

	int func_to_uretprobe()
	{
		seccomp(SECCOMP_SET_MODE_STRICT/whatever);
		return 123;
	}

by the time it is called, the kernel can't know that this function will
call seccomp/install-the-filters/etc, so prepare_uretprobe() can't know
if it is safe to use uretprobe or not.

Oleg.