From: Alexei Starovoitov <ast@fb.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>,
Andy Lutomirski <luto@amacapital.net>,
Alexei Starovoitov <ast@kernel.org>,
Djalal Harouni <tixxdz@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Daniel Borkmann <daniel@iogearbox.net>,
Greg KH <gregkh@linuxfoundation.org>,
"Luis R. Rodriguez" <mcgrof@kernel.org>,
Network Development <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
kernel-team <kernel-team@fb.com>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH net-next] modules: allow modprobe load regular elf binaries
Date: Fri, 9 Mar 2018 10:58:06 -0800 [thread overview]
Message-ID: <77cdc9f5-b51c-a18d-5422-763cc4e76279@fb.com> (raw)
In-Reply-To: <CA+55aFzJEkUGfRkKqc8twaDSdSH_r_OWnFm-e4uNQf4SrJy7-A@mail.gmail.com>
On 3/9/18 10:50 AM, Linus Torvalds wrote:
> On Fri, Mar 9, 2018 at 10:43 AM, Kees Cook <keescook@chromium.org> wrote:
>>
>> Module loading (via kernel_read_file()) already uses
>> deny_write_access(), and so does do_open_execat(). As long as module
>> loading doesn't call allow_write_access() before the execve() has
>> started in the new implementation, I think we'd be covered here.
>
> No. kernel_read_file() only does it *during* the read.
>
> So there's a huge big honking gap between the two.
>
> Also, the second part of my suggestion was to be entirely synchronous
> with the whole execution of the process, and do it within the "we do
> mutual exclusion fo rmodules with the same name" logic.
>
> Note that Andrei's patch uses UMH_WAIT_EXEC. That's basically
> "vfork+exec" - it only waits for the exec to have started, it doesn't
> wait for the whole thing.
It's not waiting for the whole thing, because once bpfilter starts it
stays running/sleeping because it's stateful. It needs normal
malloc-ed memory to keep the state of iptable->bpf translation that
it will use later during subsequent translation calls.
Theoretically it can use bpf maps pinned in kernel memory to keep
this state, but then it's non-swappable. It's better to keep bpfilter
state in its own user memory.
next prev parent reply other threads:[~2018-03-09 18:59 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-06 1:34 [PATCH net-next] modules: allow modprobe load regular elf binaries Alexei Starovoitov
2018-03-06 2:13 ` Randy Dunlap
2018-03-06 3:02 ` Alexei Starovoitov
2018-03-06 11:05 ` Greg KH
2018-03-07 1:07 ` Alexei Starovoitov
2018-03-07 3:24 ` Greg KH
2018-03-06 19:12 ` Linus Torvalds
2018-03-06 23:42 ` Chris Mason
2018-05-02 9:12 ` Jesper Dangaard Brouer
2018-03-06 20:01 ` Andy Lutomirski
2018-03-06 20:26 ` Linus Torvalds
2018-03-07 17:22 ` David Miller
2018-03-08 1:23 ` Luis R. Rodriguez
2018-03-08 23:07 ` Alexei Starovoitov
2018-03-09 1:58 ` Luis R. Rodriguez
2018-03-09 0:24 ` Kees Cook
2018-03-09 0:57 ` Alexei Starovoitov
2018-03-09 1:04 ` Andy Lutomirski
2018-03-09 1:25 ` Alexei Starovoitov
2018-03-09 1:24 ` Kees Cook
2018-03-09 0:59 ` Andy Lutomirski
2018-03-09 1:20 ` Alexei Starovoitov
2018-03-09 2:12 ` Andy Lutomirski
2018-03-09 2:31 ` David Miller
2018-03-09 3:10 ` Andy Lutomirski
2018-03-09 3:27 ` Alexei Starovoitov
2018-03-09 1:38 ` Linus Torvalds
2018-03-09 1:44 ` Kees Cook
2018-03-09 3:06 ` Linus Torvalds
2018-03-09 3:17 ` Linus Torvalds
2018-03-09 3:54 ` Andy Lutomirski
2018-03-09 5:08 ` Alexei Starovoitov
2018-03-09 15:16 ` Andy Lutomirski
2018-03-09 15:39 ` Alexei Starovoitov
2018-03-09 16:24 ` Andy Lutomirski
2018-03-09 17:32 ` Alexei Starovoitov
2018-03-09 18:15 ` Greg KH
2018-03-09 18:23 ` Andy Lutomirski
2018-03-09 18:29 ` Greg KH
2018-03-09 18:50 ` Alexei Starovoitov
2018-03-09 18:55 ` David Miller
2018-03-09 19:37 ` Andy Lutomirski
2018-03-10 1:43 ` Alexei Starovoitov
2018-03-11 2:17 ` Andy Lutomirski
2018-03-09 18:17 ` Linus Torvalds
2018-03-09 18:35 ` David Miller
2018-03-09 18:43 ` Kees Cook
2018-03-09 18:50 ` Linus Torvalds
2018-03-09 18:54 ` Kees Cook
2018-03-09 18:58 ` Alexei Starovoitov [this message]
2018-03-12 12:02 ` Edward Cree
2018-03-12 17:49 ` Alexei Starovoitov
2018-03-09 18:48 ` Andy Lutomirski
2018-03-09 18:53 ` Linus Torvalds
2018-03-09 18:57 ` David Miller
2018-03-09 19:12 ` Linus Torvalds
2018-03-09 19:38 ` Linus Torvalds
2018-03-09 19:45 ` Andy Lutomirski
2018-03-10 2:34 ` Alexei Starovoitov
2018-03-10 14:08 ` Luis R. Rodriguez
2018-03-10 15:16 ` Luis R. Rodriguez
2018-03-10 15:34 ` Luis R. Rodriguez
2018-03-12 17:22 ` Alexei Starovoitov
2018-03-13 8:48 ` Greg Kroah-Hartman
2018-03-22 20:54 ` Luis R. Rodriguez
2018-03-22 22:15 ` Andy Lutomirski
2018-03-22 22:21 ` Alexei Starovoitov
2018-03-23 2:47 ` Luis R. Rodriguez
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