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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250117015730.GC2610@redhat.com>
Date: Fri, 17 Jan 2025 02:57:30 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Jiri Olsa <olsajiri@...il.com>, Aleksa Sarai <cyphar@...har.com>,
	Eyal Birger <eyal.birger@...il.com>,
	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 01/17, Masami Hiramatsu wrote:
>
> On Tue, 14 Jan 2025 15:21:29 +0100
> Jiri Olsa <olsajiri@...il.com> wrote:
>
> > On Tue, Jan 14, 2025 at 12:21:07PM +0100, Oleg Nesterov wrote:
> > >
> > > But please not that the uretprobed function can return any value
> > > including -ENOSYS, and this is what sys_uretprobe() has to return.
> >
> > right, uretprobe syscall returns value of the uretprobed function,
> > so we can't use any reserved value
>
> We can make uretprobe (entry) fail if the return value is one of
> errno or NULL, because it *knows* what the return value here.

I fail to understand... Could you spell please?

But whatever you meant, I don't think it is right, sorry.. please
correct me.

"it *knows*". Who it? How can it know??? I'd say "it" can't know,
but probably I missed your point.

Not to mention it doesn't really matter. It is not safe to even try
to do

	movq $__NR_uretprobe, %rax
	syscall

if the probed task has seccomp filters.

Oleg.