netdev - Re: [PATCH net] netlink: Relax attr validation for fixed length types

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Message-Id: <20171206.141219.173668003844865413.davem@davemloft.net>
Date:   Wed, 06 Dec 2017 14:12:19 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     dsahern@...il.com
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net] netlink: Relax attr validation for fixed length
 types

From: David Ahern <dsahern@...il.com>
Date: Tue,  5 Dec 2017 12:55:40 -0700

> Commit 28033ae4e0f5 ("net: netlink: Update attr validation to require
> exact length for some types") requires attributes using types NLA_U* and
> NLA_S* to have an exact length. This change is exposing bugs in various
> userspace commands that are sending attributes with an invalid length
> (e.g., attribute has type NLA_U8 and userspace sends NLA_U32). While
> the commands are clearly broken and need to be fixed, users are arguing
> that the sudden change in enforcement is breaking older commands on
> newer kernels for use cases that otherwise "worked".
> 
> Relax the validation to print a warning mesage similar to what is done
> for messages containing extra bytes after parsing.
> 
> Fixes: 28033ae4e0f5 ("net: netlink: Update attr validation to require exact length for some types")
> Signed-off-by: David Ahern <dsahern@...il.com>

David, please address Johannes's feedback and I'll apply this.

Thank you.