From: Cyrill Gorcunov <gorcunov@gmail.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>,
Andrew Vagin <avagin@gmail.com>,
Aditya Kali <adityakali@google.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org, criu@openvz.org,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <keescook@chromium.org>
Subject: Re: [CRIU] [PATCH 1/3] prctl: reduce permissions to change boundaries of data, brk and stack
Date: Sat, 15 Feb 2014 10:29:22 +0400 [thread overview]
Message-ID: <20140215062922.GA22779@moon> (raw)
In-Reply-To: <877g8xphw9.fsf@xmission.com>
On Fri, Feb 14, 2014 at 12:18:46PM -0800, Eric W. Biederman wrote:
> >> >
> >> > Why can't you have the process of interest do:
> >> > ptrace(PTRACE_ATTACHME);
> >> > execve(executable, args, ...);
> >> >
> >> > /* Have the ptracer inject the recovery/fixup code */
> >> > /* Fix up the mostly correct process to look like it has been
> >> > * executing for a while.
> >> > */
> >
> > Erik, it seems I don't understand how it will help us to restore
> > the mm fields mentioned above?
>
> Because exec is how those mm fields are set when you don't use
> prctl_set_mm. So execpt for the stack and the brk limits that
> will simply result in the values being set to what the usually
> would be set to.
Yes, all these fields are set up by kernel's elf loader but this
routine is a way more time consuming than a clone call. But gimme
some time to examine all possible problems we might have with such
approach and if there a way to solve them.
> >> Let's imagine we do that.
> >>
> >> This means, that the whole memory contents should be restored _after_
> >> the execve() call, since the execve() flushes old mappings. In
> >> that case we lose the ability to preserve any shared memory regions
> >> between any two processes. This "shared" can be either regular
> >> MAP_SHARED mappings or MAP_ANONYMOUS but still not COW-ed ones.
next prev parent reply other threads:[~2014-02-15 6:29 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-14 14:13 [PATCH RFC 0/3] c/r: add ability to restore mm attributes in a non-root userns Andrey Vagin
2014-02-14 14:13 ` [PATCH 1/3] prctl: reduce permissions to change boundaries of data, brk and stack Andrey Vagin
2014-02-14 16:05 ` Eric W. Biederman
2014-02-14 17:43 ` Andrew Vagin
2014-02-14 18:01 ` [CRIU] " Cyrill Gorcunov
2014-02-14 19:16 ` Eric W. Biederman
2014-02-14 19:47 ` Pavel Emelyanov
2014-02-14 20:06 ` Cyrill Gorcunov
2014-02-14 20:18 ` Eric W. Biederman
2014-02-15 6:29 ` Cyrill Gorcunov [this message]
2014-02-15 23:01 ` Eric W. Biederman
2014-02-14 20:09 ` Eric W. Biederman
2014-02-17 8:34 ` Pavel Emelyanov
2014-02-17 8:52 ` Cyrill Gorcunov
2014-02-17 16:57 ` Pavel Emelyanov
2014-03-07 13:51 ` Pavel Emelyanov
2014-02-14 20:44 ` Andrey Wagin
2014-02-15 23:05 ` Eric W. Biederman
2014-02-14 14:13 ` [PATCH 2/3] capabilities: add a secure bit to allow changing a task exe link Andrey Vagin
2014-02-18 4:53 ` Serge E. Hallyn
2014-02-14 14:13 ` [PATCH 3/3] prctl: allow to use PR_MM_SET_* which affect only a current task Andrey Vagin
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