netdev - Re: Question on netlink nested attributes

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 for Android: free password hash cracker in your pocket

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

Date:	Wed, 27 Aug 2008 22:57:56 +0200
From:	Thomas Graf <tgraf@...g.ch>
To:	"Duyck, Alexander H" <alexander.h.duyck@...el.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"shemminger@...l.org" <shemminger@...l.org>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
Subject: Re: Question on netlink nested attributes

* Duyck, Alexander H <alexander.h.duyck@...el.com> 2008-08-20 15:20
> I have a regression that was found in 2.6.26 in which the multiqueue option for the prio qdisc quit working after the commit referenced at http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.26.y.git;a=commit;h=b9a2f2e450b0f770bb4347ae8d48eb2dea701e24
> 
> The issue appears to be that the prio qdisc and the netem qdisc have two different ways that they are nesting the attributes they are passing to the qdisc layer but both use nla_parse_nested_compat.
> 
> The prio qdisc is laying out the message something like:
> hdr0(data+hdr1(hdr2(data)+hdr3(data)))

This format should use nla_parse_nested(data+sizeof(*data)), this is
the "regular" way.

> The netem qdisc is laying out the message something like:
> hdr0(data+hdr2(data)+hdr3(data))

This is the outdated way and thus "compat". Use
nla_parse_nested_compat().

> The question is which format is correct.  Just need to know so I can go about getting them both working the same way.

The format as used in prio qdisc is the preferred format. Nevertheless,
the netem format can't be changed, it is part of the ABI, therefore the
compat functions were added.
--
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