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

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Message-ID: <CAEf4BzYPh5CpZWxGnFmtasZ9THmmW0ShUw2j4=K9X5+=LzpRaw@mail.gmail.com>
Date: Fri, 17 Jan 2025 11:34:09 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Eyal Birger <eyal.birger@...il.com>
Cc: Oleg Nesterov <oleg@...hat.com>, Masami Hiramatsu <mhiramat@...nel.org>, 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 11:24 AM Eyal Birger <eyal.birger@...il.com> wrote:
>
> On Fri, Jan 17, 2025 at 9:51 AM Andrii Nakryiko
> <andrii.nakryiko@...il.com> wrote:
> >
> > 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?
>
> I like the more generic approach and keeping CONFIG_X86 out of seccomp,
> and more generic than uprobes, however, I'm not sure where a common part
> to place it which includes arch/x86/include/asm/syscall.h would be. And
> as mentioned before, this would make this bugfix more complex to backport.
>
> For that reason I wouldn't refactor handling rt_sigreturn as part of
> this fix.
>

SGTM, it can always be improved later, if necessary

> Thanks!
> Eyal.