netdev - Re: [Patch 4/5] Network Drop Monitor: Adding drop monitor implementation & Netlink protocol

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: <49D4CECA.3010703@trash.net>
Date:	Thu, 02 Apr 2009 16:42:18 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	David Miller <davem@...emloft.net>, nhorman@...driver.com,
	zbr@...emap.net, netdev@...r.kernel.org, kuznet@....inr.ac.ru,
	pekkas@...core.fi, jmorris@...ei.org, yoshfuji@...ux-ipv6.org
Subject: Re: [Patch 4/5] Network Drop Monitor: Adding drop monitor	implementation
 & Netlink protocol

Herbert Xu wrote:
> On Thu, Apr 02, 2009 at 02:52:23AM -0700, David Miller wrote:
>> It has to do with how the netlink attributes get packed together
>> into the messages.  It's this crap:
>>
>> #define NLMSG_ALIGNTO	4
>> #define NLMSG_ALIGN(len) ( ((len)+NLMSG_ALIGNTO-1) & ~(NLMSG_ALIGNTO-1) )
>>  ...
>> #define NLMSG_NEXT(nlh,len)	 ((len) -= NLMSG_ALIGN((nlh)->nlmsg_len), \
>> 				  (struct nlmsghdr*)(((char*)(nlh)) + NLMSG_ALIGN((nlh)->nlmsg_len)))
>>
>> Thus, nothing in an nlmsg can ever be more than 4 byte aligned.
>> And this is hard coded into the protocol.
> 
> Ah yes, this is the killer.
> 
> I suppose we can modify in-kernel helpers like nla_parse to deal
> with that by copying if it's unaligned.  Though we'll have to
> figure out how to free the memory.

Actually we should be fine since the current netlink helpers only do
bytewise copying anyways. And I think we've pretty much gotten rid of
all the raw attribute accesses.
--
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