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

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Message-ID: <CAEf4BzbVZuYEXro57FhZyTetaKFZ1xr9FGn5iyi8Nwa+LbA0vA@mail.gmail.com>
Date: Wed, 15 Jan 2025 10:20:34 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Oleg Nesterov <oleg@...hat.com>, Jiri Olsa <olsajiri@...il.com>, 
	Eyal Birger <eyal.birger@...il.com>, Aleksa Sarai <cyphar@...har.com>, 
	Masami Hiramatsu <mhiramat@...nel.org>, linux-kernel <linux-kernel@...r.kernel.org>, 
	linux-trace-kernel <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>, Peter Zijlstra <peterz@...radead.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, X86 ML <x86@...nel.org>, 
	Linux API <linux-api@...r.kernel.org>, Andrii Nakryiko <andrii@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Alexei Starovoitov <ast@...nel.org>, 
	"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 Wed, Jan 15, 2025 at 9:56 AM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> On Wed, Jan 15, 2025 at 7:06 AM Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > Or we can change __secure_computing() to do nothing if
> > this_syscall == __NR_uretprobe.
>
> I think that's the best way forward.
> seccomp already allowlists sigreturn syscall.
> uretprobe syscall is in the same category.

+1, we will have a similar problem with sys_uprobe (when it's added).
Just like rt_sigreturn, these are special kernel-only mechanisms, and
the kernel already protects itself from any user abuse. So I think we
should have a way to ensure those special syscalls can go through
regardless of seccomp.

> See __secure_computing_strict.