Re: [RFC PATCH] net/memif: change socket listener owner uid/gid

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 15 Nov 2022 20:44:41 +0000
Junxiao Shi <git@mail1.yoursunny.com> wrote:

> +static int
> +memif_set_owner_uid(const char *key __rte_unused, const char *value, void *extra_args)
> +{
> +	uid_t *uid = (uid_t *)extra_args;
> +	*uid = strtoul(value, NULL, 10);
> +	return 0;
> +}
> +
> +static int
> +memif_set_owner_gid(const char *key __rte_unused, const char *value, void *extra_args)
> +{
> +	gid_t *gid = (gid_t *)extra_args;
> +	*gid = strtoul(value, NULL, 10);
> +	return 0;
> +}
> +

This should be one function and it should check for valid arguments.
Things like not a number, extra characters, and out of range.

Modern Linux allows 32 bits of uid. with some values like -1 reserved.
On a 64 bit system like most DPDK usage, sizeof(unsigned long) is 64 bits.

Since uid and gid have same restrictions, then something like this (untested):

static int strtouid(const char *value, uint32_t *id)
{
	unsigned long val;
	char *endp;

	val = strtoul(value, &endp, 10);
	if (*value == '\0' || *endp != '\0')
		return -EINVAL;
	if (val >= UINT32_MAX)
		return -ERANGE;
	*id = val;
	return 0;
}