linux-kernel - Re: Crash when attaching uretprobes to processes running in Docker

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Message-ID: <Z4Z7OkrtXBauaLcm@krava>
Date: Tue, 14 Jan 2025 15:56:58 +0100
From: Jiri Olsa <olsajiri@...il.com>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Eyal Birger <eyal.birger@...il.com>, Jiri Olsa <olsajiri@...il.com>,
	Aleksa Sarai <cyphar@...har.com>, mhiramat@...nel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-trace-kernel@...r.kernel.org,
	BPF-dev-list <bpf@...r.kernel.org>,
	Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>, peterz@...radead.org,
	tglx@...utronix.de, bp@...en8.de, x86@...nel.org,
	linux-api@...r.kernel.org, Andrii Nakryiko <andrii@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii.nakryiko@...il.com>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>, rafi@....io,
	Shmulik Ladkani <shmulik.ladkani@...il.com>
Subject: Re: Crash when attaching uretprobes to processes running in Docker

On Tue, Jan 14, 2025 at 03:33:13PM +0100, Oleg Nesterov wrote:
> On 01/14, Eyal Birger wrote:
> >
> > FWIW If I change the seccomp policy to SCMP_ACT_KILL this still fails.
> 
> Ah... I don't know what SCMP_ACT_KILL is, but indeed, in general it is
> not safe to even try to call sys_uretprobe() if it is filtered.
> 
> Say, __secure_computing(SECCOMP_MODE_STRICT)->__secure_computing_strict()
> does do_exit(SIGKILL) :/

ugh.. could we just 'disable' uretprobe trampoline when seccomp gets enabled?
overwrite first byte with int3.. and similarly check on seccomp when installing
uretprobe and switch to int3

jirka