netdev - [PATCH v2 0/2] netlink: extended attribute validation

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Message-Id: <20180927092836.6117-1-johannes@sipsolutions.net>
Date:   Thu, 27 Sep 2018 11:28:34 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Cc:     Michal Kubecek <mkubecek@...e.cz>
Subject: [PATCH v2 0/2] netlink: extended attribute validation

This adds further netlink attribute validation:
 * min/max/range validation
 * validation through a custom function pointer

This is useful to
 * reduce boilerplate code in command handling code, if attributes
   are used commonly across different commands
 * get more extended ACK error messages/attribute pointers
 * ensure attributes are valid even when ignored
   (though this might be a problem when converting existing code)

Changes since v1:
 * split off validate_type from type and use that for min/max/range
   and function; this is better because the range is limited to the
   range of s16 and so things like "u16 with minimum value 1" couldn't
   be expressed earlier
 * add macros for this, e.g. NLA_POLICY_MIN(NLA_U16, 1) for the case
   mentioned in the previous bullet

Using this pretty much in all places where applicable in nl80211
reduces the code size there by about 1.8KiB, with just a minimal
code increase in lib/nlattr.o.

johannes