netdev - Re: [RFC] remove NLA_STRING NUL trimming

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Date:	Fri, 23 Mar 2007 15:40:43 +0100
From:	Johannes Berg <johannes@...solutions.net>
To:	Thomas Graf <tgraf@...g.ch>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: [RFC] remove NLA_STRING NUL trimming

On Fri, 2007-03-23 at 15:20 +0100, Thomas Graf wrote:

> It's not really removed, the trailing NUL is just ignored when checking
> the length of the attribute. 

Good point.

> This is needed for older netlink families
> where strings are not always NUL terminated, yet we still need to accept
> the additional byte needed in case it is present. This validation is
> strictly necessary, otherwise nla_strcmp() and others will fail.

Ok.

> > For wireless, we have a few places where we need to be able to accept
> > any (even binary) values, for example for the SSID; the SSID can validly
> > end with \0 and I'd still love to be able to take advantage of
> > NLA_STRING and .len = 32 so I don't need to check the length myself.
> > However, given the code above, an SSID with a terminating \0 would be
> > reduced by one character.
> 
> I suggest that you introduce NLA_BINARY which enforces a maximum length.

Alright, I'll post a patch in a bit.

johannes

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