From: Alexander Duyck <alexander.duyck@gmail•com>
To: Jamal Hadi Salim <jhs@mojatatu•com>
Cc: "Eric W. Biederman" <ebiederm@xmission•com>,
David Miller <davem@davemloft•net>,
netdev@vger•kernel.org, alexander.h.duyck@intel•com
Subject: Re: [PATCH 0/2] net_sched: Remove broken tc actions
Date: Sun, 27 Oct 2013 13:37:48 -0700 [thread overview]
Message-ID: <526D799C.9050905@gmail.com> (raw)
In-Reply-To: <526D463E.6040000@mojatatu.com>
On 10/27/2013 09:58 AM, Jamal Hadi Salim wrote:
> On 10/27/13 09:40, Eric W. Biederman wrote:
>>
>> While auditing the code to make certain it would be safe to enable the
>> user namespace root to use tc actions I stumbled on the strange fact
>> that two of the tc modules in the kernel have been broken for more
>> years than I care to think about.
>>
>> In particular neither of these two modules implements the tc_action_ops
>> lookup method. Which means that in practice neither RTM_GETACTION nor
>> RTM_DELACTION work. And with RTM_DELACTION broken that looks like a
>> permanent leak of kernel memory to me.
>>
>>
>> A leak I am not happy at root having and certainly not something I want
>> to allow unprivileged users access to.
>>
>> On the premise that 5+ years is too long to wait for someone to notice,
>> complain and get this code fixed let's just remove these broken tc
>> modules.
>>
>
>
> Nah, dude.
> You dont have to implement the get/del. Actions are typically bound
> to filters; when the filters disappears the action is destroyed.
> You Get the filter, you Get the bound actions.
> you can add actions without filters - but in such a case, for both
> of these ones you picked, you can dump or flush them unless they are
> bound to a filter. Thats the minimal requirement (which is met).
>
> What is your use case to need explicit get/del?
> Given act_simple is pedagogical in nature, I think
> that will be useful for illustration purposes.
>
> cheers,
> jamal
The primary use case for act_skbedit was to have it associated with a
filter. I based it off of act_simple so it isn't surprising that it
inherited this issue.
>From what I can tell all of the other actions are just using
tcf_hash_search for lookup. Is there anything special that is needed in
order to add the lookup call, or could we just add a one liner
associating simple and skbedit lookup with tcf_hash_search?
Thanks,
Alex
next prev parent reply other threads:[~2013-10-27 20:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-27 13:40 [PATCH 0/2] net_sched: Remove broken tc actions Eric W. Biederman
2013-10-27 13:42 ` [PATCH 1/2] net_sched: Remove broken act_skbedit Eric W. Biederman
2013-10-27 13:43 ` [PATCH 2/2] net_sched: Remove broken act_simple Eric W. Biederman
2013-10-27 16:58 ` [PATCH 0/2] net_sched: Remove broken tc actions Jamal Hadi Salim
2013-10-27 20:37 ` Alexander Duyck [this message]
2013-10-28 22:57 ` Jamal Hadi Salim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=526D799C.9050905@gmail.com \
--to=alexander.duyck@gmail$(echo .)com \
--cc=alexander.h.duyck@intel$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=ebiederm@xmission$(echo .)com \
--cc=jhs@mojatatu$(echo .)com \
--cc=netdev@vger$(echo .)kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox