netdev - Re: [PATCH] iproute2 flush: handle larger tables and deleted entries

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4e0db5bc0907140945i3190cfb7g7b3e6a0f1c10bc8a@mail.gmail.com>
Date:	Tue, 14 Jul 2009 09:45:47 -0700
From:	Gautam Kachroo <gk@...stanetworks.com>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] iproute2 flush: handle larger tables and deleted entries

On Tue, Jul 14, 2009 at 2:38 AM, Patrick McHardy<kaber@...sh.net> wrote:
> Gautam Kachroo wrote:
>> use a new netlink socket when sending flush messages to avoid reading
>> any pending data on the existing netlink socket.
>>
>> read all of the response from the netlink request -- this response can
>> be split over multiple recv calls, pretty much one per netlink request
>> message. ENOENT errors, which correspond to attempts to delete an
>> already deleted entry, are ignored. Other errors are not ignored.
>
> In which case would there be any pending data? From what I can see,
> this can only happen when using batching, but in that case the
> previous command should continue reading until it has received all
> responses (which the netlink functions appear to be doing properly).

What is the "previous command"?
Are you referring to rtnl_dump_filter? If rtnl_send_check comes across
a failure, rtnl_dump_filter will not continue reading.

Here's the situation that I'm referring to:

If rtnl_send_check detects an error, it returns -1. rtnl_send_check is
called from flush_update. The multiple implementations of flush_update
(e.g. in ipneigh.c, ipaddress.c) propagate this return value to their
caller, e.g. print_neigh or print_addrinfo.

print_neigh, print_addrinfo, etc. are called from rtnl_dump_filter.
rtnl_dump_filter sits in a loop calling recvmsg on the netlink socket.
However, it returns the error value if the filter function (e.g.
print_neigh) returns an error. In this case, rtnl_dump_filter can
return before it's read all the responses.
The error return from rtnl_dump_filter causes the program to exit.

Note, rtnl_send_check treats any pending data as an error. It could be
changed to only complain if the response contains NLMSG_ERROR
messages, but that delays error detection because it will read all the
responses to the dump request first.

thanks,
-gk
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html