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From: Tycho Andersen <tycho@tycho.ws>
To: Sargun Dhillon <sargun@sargun.me>
Cc: linux-kernel@vger.kernel.org,
	containers@lists.linux-foundation.org, linux-api@vger.kernel.org
Subject: Re: [RFC PATCH] ptrace: add PTRACE_GETFD request
Date: Fri, 6 Dec 2019 07:10:45 -0700	[thread overview]
Message-ID: <20191206141045.GA22803@cisco> (raw)
In-Reply-To: <20191205234450.GA26369@ircssh-2.c.rugged-nimbus-611.internal>

On Thu, Dec 05, 2019 at 11:44:53PM +0000, Sargun Dhillon wrote:
> PTRACE_GETFD is a generic ptrace API that allows the tracer to
> get file descriptors from the traceee.
> 
> The primary reason to use this syscall is to allow sandboxers to

I might change this to "one motivation to use this ptrace command",
because I'm sure people will invent other crazy uses soon after it's
added :)

> take action on an FD on behalf of the tracee. For example, this
> can be combined with seccomp's user notification feature to extract
> a file descriptor and call privileged syscalls, like binding
> a socket to a privileged port.

This can already be accomplished via injecting parasite code like CRIU
does; adding a ptrace() command like this makes it much nicer to be
sure, but it is redundant.

Tycho

  parent reply	other threads:[~2019-12-06 14:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-05 23:44 [RFC PATCH] ptrace: add PTRACE_GETFD request Sargun Dhillon
2019-12-06  2:38 ` Jann Horn
2019-12-06  6:16   ` Sargun Dhillon
2019-12-06  6:52     ` Aleksa Sarai
2019-12-06  8:25 ` Christian Brauner
2019-12-06 12:23   ` Oleg Nesterov
2019-12-06 14:10 ` Tycho Andersen [this message]
2019-12-06 19:03   ` Sargun Dhillon
2019-12-06 19:05     ` Jann Horn
2019-12-06 19:05       ` Jann Horn
2019-12-06 20:45 ` Andy Lutomirski

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