netdev - Re: [RFC 1/6] netlink: add nlmsg_validate_strict() & nla_validate

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Message-ID: <20190321225046.t5aatcq6vtfxciox@breakpoint.cc>
Date:   Thu, 21 Mar 2019 23:50:46 +0100
From:   Florian Westphal <fw@...len.de>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     netdev@...r.kernel.org, David Ahern <dsa@...ulusnetworks.com>,
        Johannes Berg <johannes.berg@...el.com>
Subject: Re: [RFC 1/6] netlink: add nlmsg_validate_strict() &
 nla_validate_strict()

Johannes Berg <johannes@...solutions.net> wrote:
> + * nla_validate_strict - Strictly validate a stream of attributes
> + * @head: head of attribute stream
> + * @len: length of attribute stream
> + * @maxtype: maximum attribute type to be expected
> + * @policy: validation policy
> + * @extack: extended ACK report struct
> + *
> + * Validates all attributes in the specified attribute stream against the
> + * specified policy. Attributes with a type exceeding maxtype will be
> + * ignored.
      ^^^^^^^^
rejected?

> +int nla_validate_strict(const struct nlattr *head, int len, int maxtype,
> +			const struct nla_policy *policy,
> +			struct netlink_ext_ack *extack)
> +{
> +	const struct nlattr *nla;
> +	int rem;
> +
> +	nla_for_each_attr(nla, head, len, rem) {
> +		u16 type = nla_type(nla);
> +		int err;
> +
> +		if (type == 0 || type > maxtype) {
> +			NL_SET_ERR_MSG(extack, "Unknown attribute type");

Sure looks like it, and thats good.