netdev - Re: [PATCH 2/6] netlink: extend policy range validation

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Date:   Mon, 29 Apr 2019 22:49:51 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     johannes@...solutions.net
Cc:     netdev@...r.kernel.org, dsa@...ulusnetworks.com,
        pablo@...filter.org, johannes.berg@...el.com
Subject: Re: [PATCH 2/6] netlink: extend policy range validation

From: Johannes Berg <johannes@...solutions.net>
Date: Fri, 26 Apr 2019 14:13:02 +0200

>   *                         NLA_POLICY_RANGE() macros.
> + *    NLA_U8,
> + *    NLA_U16,
> + *    NLA_U32,
> + *    NLA_U64              If the validation_type field instead is set to
> + *                         NLA_VALIDATE_RANGE_PTR, `range' must be a pointer
> + *                         to a struct netlink_range_validation that indicates
> + *                         the min/max values.
> + *                         Use NLA_POLICY_FULL_RANGE().
> + *    NLA_S8,
> + *    NLA_S16,
> + *    NLA_S32,
> + *    NLA_S64              If the validation_type field instead is set to
> + *                         NLA_VALIDATE_RANGE_PTR, `range_signed' must be a
> + *                         pointer to a struct netlink_range_validation_signed
> + *                         that indicates the min/max values.
> + *                         Use NLA_POLICY_FULL_RANGE_SIGNED().

Documentation and datastructure says that "range_signed" member should be set
for signed ranges, however:

> +#define NLA_POLICY_FULL_RANGE(tp, _range) {		\
> +	.type = NLA_ENSURE_UINT_TYPE(tp),		\
> +	.validation_type = NLA_VALIDATE_RANGE_PTR,	\
> +	.range = _range,				\
> +}
> +
> +#define NLA_POLICY_FULL_RANGE_SIGNED(tp, _range) {	\
> +	.type = NLA_ENSURE_SINT_TYPE(tp),		\
> +	.validation_type = NLA_VALIDATE_RANGE_PTR,	\
> +	.range = _range,				\
> +}

The NLA_POLICY_FULL_RANGE_SIGNED macros sets 'range' not 'range_signed'.

Also, since range and range_signed are in a union however there is only one
NLA_VALIDATE_RANGE_PTR type, how does one differentiate between signed and
unsigned ranges exactly?

Thanks.