Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 25 Jul 2023 21:36:52 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Lin Ma <linma@zju.edu.cn>, jesse.brandeburg@intel.com,
        anthony.l.nguyen@intel.com, davem@davemloft.net,
        edumazet@google.com, pabeni@redhat.com, richardcochran@gmail.com,
        ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org,
        john.fastabend@gmail.com, intel-wired-lan@lists.osuosl.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] i40e: Add length check for IFLA_AF_SPEC parsing
Message-ID: <20230725183652.GR11388@unreal>
References: <20230723075042.3709043-1-linma@zju.edu.cn>
 <20230724174435.GA11388@unreal>
 <20230724142155.13c83625@kernel.org>
 <20230725054046.GK11388@unreal>
 <20230725095327.385616f1@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230725095327.385616f1@kernel.org>
Precedence: bulk

On Tue, Jul 25, 2023 at 09:53:27AM -0700, Jakub Kicinski wrote:
> On Tue, 25 Jul 2023 08:40:46 +0300 Leon Romanovsky wrote:
> > > Empty attributes are valid, we can't do that.  
> > 
> > Maybe Lin can add special version of nla_for_each_nested() which will
> > skip these empty NLAs, for code which don't allow empty attributes.
> 
> It's way too arbitrary. Empty attrs are 100% legit, they are called
> NLA_FLAG in policy parlance. They are basically a boolean.

I afraid that these nla_length() checks will be copied all other the
kernel without any understanding and netlink API doesn't really provide
any hint when length checks are needed and when they don't.

Thank