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From: Gabriel Krisman Bertazi <krisman@collabora.com>
To: ebiederm@xmission.com (Eric W. Biederman)
Cc: luto@kernel.org, tglx@linutronix.de, keescook@chromium.org,
	gofmanp@gmail.com, christian.brauner@ubuntu.com,
	peterz@infradead.org, willy@infradead.org, shuah@kernel.org,
	linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	linux-kselftest@vger.kernel.org, x86@kernel.org,
	kernel@collabora.com
Subject: Re: [PATCH v8 3/7] kernel: Implement selective syscall userspace redirection
Date: Thu, 01 Jul 2021 13:09:21 -0400	[thread overview]
Message-ID: <87mtr6gdvi.fsf@collabora.com> (raw)
In-Reply-To: <8735szowmu.fsf@disp2133> (Eric W. Biederman's message of "Wed, 30 Jun 2021 16:44:41 -0500")

ebiederm@xmission.com (Eric W. Biederman) writes:

> Why does do_syscal_user_dispatch call do_exit(SIGSEGV) and
> do_exit(SIGSYS) instead of force_sig(SIGSEGV) and force_sig(SIGSYS)?
>
> Looking at the code these cases are not expected to happen, so I would
> be surprised if userspace depends on any particular behaviour on the
> failure path so I think we can change this.

Hi Eric,

There is not really a good reason, and the use case that originated the
feature doesn't rely on it.

Unless I'm missing yet another problem and others correct me, I think
it makes sense to change it as you described.

> Is using do_exit in this way something you copied from seccomp?

I'm not sure, its been a while, but I think it might be just that.  The
first prototype of SUD was implemented as a seccomp mode.

> The reason I am asking is that by using do_exit you deprive userspace
> of the change to catch the signal handler and try and fix things.
>
> Also by using do_exit only a single thread of a multi-thread application
> is terminated which seems wrong.
>
> I am asking because I am going through the callers of do_exit so I can
> refactor things and clean things up and this use just looks wrong.

Thanks,

-- 
Gabriel Krisman Bertazi

  reply	other threads:[~2021-07-01 17:09 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-27 19:32 [PATCH v8 0/7] Syscall User Dispatch Gabriel Krisman Bertazi
2020-11-27 19:32 ` [PATCH v8 1/7] x86: vdso: Expose sigreturn address on vdso to the kernel Gabriel Krisman Bertazi
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-11-27 19:32 ` [PATCH v8 2/7] signal: Expose SYS_USER_DISPATCH si_code type Gabriel Krisman Bertazi
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-11-27 19:32 ` [PATCH v8 3/7] kernel: Implement selective syscall userspace redirection Gabriel Krisman Bertazi
2020-12-01 22:57   ` Kees Cook
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-12-02 14:12   ` tip-bot2 for Gabriel Krisman Bertazi
2021-06-30 21:44   ` [PATCH v8 3/7] " Eric W. Biederman
2021-07-01 17:09     ` Gabriel Krisman Bertazi [this message]
2020-11-27 19:32 ` [PATCH v8 4/7] entry: Support Syscall User Dispatch on common syscall entry Gabriel Krisman Bertazi
2020-12-01 22:57   ` Kees Cook
2020-12-02  0:04   ` Andy Lutomirski
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-12-02 14:12   ` tip-bot2 for Gabriel Krisman Bertazi
2020-11-27 19:32 ` [PATCH v8 5/7] selftests: Add kselftest for syscall user dispatch Gabriel Krisman Bertazi
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-12-02 14:12   ` tip-bot2 for Gabriel Krisman Bertazi
2020-11-27 19:32 ` [PATCH v8 6/7] selftests: Add benchmark " Gabriel Krisman Bertazi
2020-12-01 22:58   ` Kees Cook
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-12-02 14:12   ` tip-bot2 for Gabriel Krisman Bertazi
2020-11-27 19:32 ` [PATCH v8 7/7] docs: Document Syscall User Dispatch Gabriel Krisman Bertazi
2020-12-01 22:21   ` Jonathan Corbet
2020-12-01 23:46     ` Thomas Gleixner
2020-12-01 22:53   ` Thomas Gleixner
2020-12-02  9:38   ` [tip: core/entry] " tip-bot2 for Gabriel Krisman Bertazi
2020-12-02 14:12   ` tip-bot2 for Gabriel Krisman Bertazi
2020-12-02  0:04 ` [PATCH v8 0/7] " Andy Lutomirski

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