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

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: <CAEf4BzYhcG8waFMFoQS5dFWVkQGP6ed_0mwGTK4quN5+6-8XuA@mail.gmail.com>
Date: Fri, 17 Jan 2025 09:51:01 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Eyal Birger <eyal.birger@...il.com>, kees@...nel.org, 
	luto@...capital.net, wad@...omium.org, andrii@...nel.org, jolsa@...nel.org, 
	alexei.starovoitov@...il.com, olsajiri@...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, rostedt@...dmis.org, 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 Fri, Jan 17, 2025 at 6:10 AM Oleg Nesterov <oleg@...hat.com> wrote:
>
> On 01/17, Masami Hiramatsu wrote:
> >
> > On Fri, 17 Jan 2025 02:39:28 +0100
> > Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > > A note for the seccomp maintainers...
> > >
> > > I don't know what do you think, but I agree in advance that the very fact this
> > > patch adds "#ifdef CONFIG_X86_64" into __secure_computing() doesn't look nice.
> > >
> >
> > Indeed. in_ia32_syscall() depends arch/x86 too.
> > We can add an inline function like;
> >
> > ``` uprobes.h
> > static inline bool is_uprobe_syscall(int syscall)
> > {
>
> We can, and this is what I tried to suggest from the very beginning.
> But I agree with Eyal who decided to send the most trivial fix for
> -stable, we can add the helper later.
>
> I don't think it should live in uprobes.h and I'd prefer something
> like arch_seccomp_ignored(int) but I won't insist.

yep, I think this is the way, keeping it as a general category. Should
we also put rt_sigreturn there explicitly as well? Also, wouldn't it
be better to have it as a non-arch-specific function for something
like rt_sigreturn where defining it per each arch is cumbersome, and
have the default implementation also call into an arch-specific
function?

>
> >       // arch_is_uprobe_syscall check can be replaced by Kconfig,
> >       // something like CONFIG_ARCH_URETPROBE_SYSCALL.
>
> Or sysctl or both. This is another issue.
>
> > ``` arch/x86/include/asm/uprobes.h
> > #define arch_is_uprobe_syscall(syscall) \
> >       (IS_ENABLED(CONFIG_X86_64) && syscall == __NR_uretprobe && !in_ia32_syscall())
> > ```
>
> This won't compile if IS_ENABLED(CONFIG_X86_64) == false, __NR_uretprobe
> will be undefined.
>
> > > The problem is that we need a simple patch for -stable which fixes the real
> > > problem. We can cleanup this logic later, I think.
> >
> > Hmm, at least we should make it is_uprobe_syscall() in uprobes.h so that
> > do not pollute the seccomp subsystem with #ifdef.
>
> See above. But I won't insist.
>
> Oleg.
>