netdev - Re: [PATCH net] netfilter: xt_hashlimit: do not allow empty names

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Date:   Fri, 2 Feb 2018 12:55:22 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        Florian Westphal <fw@...len.de>,
        netfilter-devel@...r.kernel.org, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] netfilter: xt_hashlimit: do not allow empty names

On Fri, Feb 02, 2018 at 12:49:38PM +0100, Pablo Neira Ayuso wrote:
[...]
> 
> Or place this in the core, something like:
> 
> bool net_valid_name(const char *name, size_t len)
> {
>         ...
> }
> 
> then use it from dev_valid_name()
> 
> bool dev_valid_name(const char *name)
> {
>         return net_valid_name(name, IFNAMSIZ);
> }

Just to clarify, I think I prefer this approach, probably other
subsystem can benefit from this generic approach too.

BTW, I wonder if we should use strnlen() instead of strlen() in
dev_valid_name(), I guess this not useful for device name since they
are guaranteed to be nul-terminated, but netfilter this would be good
given userspace can send us a non nul-terminated string. But in
general, I think it doesn't harm to use strnlen() in dev_valid_name().

Am I missing anything in all these tricky string handling? Thanks!