linux-kernel - Re: [PATCH] net: dsa: remove deprecated strncpy

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Message-ID: <dbfb40d7-502e-40c0-bdaf-1616834b64e4@lunn.ch>
Date:   Tue, 18 Jul 2023 21:31:04 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Kees Cook <kees@...nel.org>, justinstitt@...gle.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH] net: dsa: remove deprecated strncpy

On Tue, Jul 18, 2023 at 12:11:16PM -0700, Jakub Kicinski wrote:
> On Tue, 18 Jul 2023 11:05:23 -0700 Kees Cook wrote:
> > Honestly I find the entire get_strings API to be very fragile given
> > the lack of passing the length of the buffer, instead depending on
> > the string set length lookups in each callback, but refactoring that
> > looks like a ton of work for an uncertain benefit.
> 
> We have been adding better APIs for long term, and a print helper short
> term - ethtool_sprintf(). Should we use ethtool_sprintf() here?

I was wondering about that as well. There is no variable expansion in
most cases, so the vsnprintf() is a waste of time.

Maybe we should actually add another helper:

ethtool_name_cpy(u8 **data, unsigned int index, const char *name);

Then over the next decade, slowly convert all drivers to it. And then
eventually replace the u8 with a struct including the length.

The netlink API is a bit better. It is one kAPI call which does
everything, and it holds RTNL. So it is less likely the number of
statistics will change between the calls into the driver.

	Andrew