From: Joe Lowe <joe@pismotec.com>
To: cygwin-developers@cygwin.com
Subject: Re: AF_UNIX status report
Date: Thu, 29 Oct 2020 14:53:33 -0700 [thread overview]
Message-ID: <0f945b4c-aa30-e08e-9f86-d4b41279ba10@pismotec.com> (raw)
In-Reply-To: <f02a7df2-3d72-9a52-9ad7-45ec5a980f89@cornell.edu>
On 2020-10-29 13:19, Ken Brown via Cygwin-developers wrote:
> On 10/27/2020 5:43 AM, Corinna Vinschen wrote:
>> On Oct 26 18:04, Ken Brown via Cygwin-developers wrote:
>>> I've made at least rudimentary implementations of all the
>>> fhandler_socket_unix functions (including those in select.cc) for which
>>> there were previously only placeholders.
>>>
>>> I've pushed everything to topic/af_unix, including a merge with
>>> master as of
>>> a couple days ago.
>>>
>>> I've cobbled together a few test programs and put them in
>>> winsup/cygwin/socket_tests on the topic/af_unix branch. I haven't
>>> taken the
>>> time to automate the tests, so they all have to be run
>>> interactively. There
>>> is a Makefile to build the test programs and a README.txt that shows
>>> how to
>>> run them.
>>>
>>> One thing I haven't yet done is to think about (or systematically test)
>>> datagram sockets. I'm sure there's quite a bit of code that won't
>>> work for
>>> them.
>>>
>>> Aside from datagram sockets, there are still a few things that I'm
>>> working
>>> on, but I'm close to the point where I could use some input:
>>>
>>> 1. I've littered the code in fhandler_socket_unix.cc and select.cc with
>>> FIXME comments on which I'd like advice.
>>
>> I'll look into it.
>>
>>> 2. I haven't given any thought at all as to how to implement SCM_RIGHTS
>>> ancillary data. I could definitely use suggestions on that before I
>>> start
>>> thrashing around.
>>
>> I have only vague ideas at that point. Assuming we can replace the
>> socket implemantation with the pipe implementation, what we have is a
>> pipe which can impersonate the peer at least from the server side, and
>> it knows the client process. This in turn can be used to duplicate
>> handles. So what we could do is to define fhandler methods which create
>> a matching serialization and deserialization of the fhandler data, plus
>> duplicating the handles for the other process, sent over the pipe as
>> admin package. This must work in either direction, regardless if the
>> server or the client sends the SCM_RIGHTS block.
>
> This sounds reasonable.
>
> I have no experience with serialization. Do you happen to know of a
> good example that I could look at?
>
> Thanks.
>
> Ken
I have experience building a secure implementation of SCM_RIGHTS type
functionality over named pipe on Windows. This is not a small amount of
code if you want to handle processes running as different users or
privilege levels, and if you don't want to be a source of security
vulnerabilities.
You might consider building an implementation of SCM_RIGHTS that is only
expected to work for processes running as the same user and privilege
level. At least this would be a good starting point. This would cover
the requirements of some unix code bases that use SCM_RIGHTS , and
avoids significant security issues and complexity.
Joe
next prev parent reply other threads:[~2020-10-29 21:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 22:04 Ken Brown
2020-10-27 9:43 ` Corinna Vinschen
2020-10-29 20:19 ` Ken Brown
2020-10-29 21:53 ` Joe Lowe [this message]
2020-10-30 9:20 ` Corinna Vinschen
2020-11-03 15:43 ` Ken Brown
2020-11-04 12:03 ` Corinna Vinschen
2020-11-05 14:23 ` Ken Brown
2020-11-05 17:21 ` Corinna Vinschen
2020-11-05 19:01 ` Ken Brown
2020-11-05 19:54 ` Joe Lowe
2020-11-06 4:02 ` Ken Brown
2020-11-05 23:41 ` Ken Brown
2020-11-06 9:12 ` Corinna Vinschen
2020-11-07 22:25 ` Ken Brown
2020-11-08 22:40 ` Ken Brown
2020-11-09 9:08 ` Corinna Vinschen
2020-11-17 19:57 ` Ken Brown
2020-11-18 8:34 ` Corinna Vinschen
2020-11-22 20:44 ` Ken Brown
2020-11-23 8:43 ` Corinna Vinschen
2020-11-26 17:06 ` Ken Brown
2020-12-15 17:33 ` Ken Brown
2020-12-16 9:29 ` Corinna Vinschen
2020-12-16 21:09 ` Ken Brown
2020-12-17 15:54 ` Ken Brown
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