[OpenWrt-Devel] [PATCH] net: Allow class-e address assignment via ifconfig ioctl

[Kevin 'ldir' Darbyshire-Bryant]

Hi Linus,

FYI this was backported to the Openwrt patch tree by yours truly in https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=2574c86ce66c4032e5905d46601106ccc0c69676

and the follow up fix in https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=1fdb4a7907e0290c7fe5ca3346d40782002dec7b

I await the opportunity to remove the patches for 4.9/4.14/4.19 courtesy delivery from upstream :-)

Cheers,

Kevin

> On 14 Feb 2019, at 12:22, Linus Walleij <linus.walleij at linaro.org> wrote:
> 
> From: Dave Taht <dave.taht at gmail.com>
> 
> commit 65cab850f0eeaa9180bd2e10a231964f33743edf upstream.
> 
> While most distributions long ago switched to the iproute2 suite
> of utilities, which allow class-e (240.0.0.0/4) address assignment,
> distributions relying on busybox, toybox and other forms of
> ifconfig cannot assign class-e addresses without this kernel patch.
> 
> While CIDR has been obsolete for 2 decades, and a survey of all the
> open source code in the world shows the IN_whatever macros are also
> obsolete... rather than obsolete CIDR from this ioctl entirely, this
> patch merely enables class-e assignment, sanely.
> 
> Signed-off-by: Dave Taht <dave.taht at gmail.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> ---
> - This commit is upstream in v4.20
> - This should ve applied for stable v4.19.y, v4.14.y and v4.9.y
> ---
> include/uapi/linux/in.h | 10 +++++++---
> net/ipv4/devinet.c      |  5 +++--
> net/ipv4/ipconfig.c     |  2 ++
> 3 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
> index 48e8a225b985..f6052e70bf40 100644
> --- a/include/uapi/linux/in.h
> +++ b/include/uapi/linux/in.h
> @@ -266,10 +266,14 @@ struct sockaddr_in {
> 
> #define	IN_CLASSD(a)		((((long int) (a)) & 0xf0000000) == 0xe0000000)
> #define	IN_MULTICAST(a)		IN_CLASSD(a)
> -#define IN_MULTICAST_NET	0xF0000000
> +#define	IN_MULTICAST_NET	0xe0000000
> 
> -#define	IN_EXPERIMENTAL(a)	((((long int) (a)) & 0xf0000000) == 0xf0000000)
> -#define	IN_BADCLASS(a)		IN_EXPERIMENTAL((a))
> +#define	IN_BADCLASS(a)		((((long int) (a) ) == 0xffffffff)
> +#define	IN_EXPERIMENTAL(a)	IN_BADCLASS((a))
> +
> +#define	IN_CLASSE(a)		((((long int) (a)) & 0xf0000000) == 0xf0000000)
> +#define	IN_CLASSE_NET		0xffffffff
> +#define	IN_CLASSE_NSHIFT	0
> 
> /* Address to accept any incoming messages. */
> #define	INADDR_ANY		((unsigned long int) 0x00000000)
> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index ea4bd8a52422..e38042933a27 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -941,17 +941,18 @@ static int inet_abc_len(__be32 addr)
> {
> 	int rc = -1;	/* Something else, probably a multicast. */
> 
> -	if (ipv4_is_zeronet(addr))
> +	if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))
> 		rc = 0;
> 	else {
> 		__u32 haddr = ntohl(addr);
> -
> 		if (IN_CLASSA(haddr))
> 			rc = 8;
> 		else if (IN_CLASSB(haddr))
> 			rc = 16;
> 		else if (IN_CLASSC(haddr))
> 			rc = 24;
> +		else if (IN_CLASSE(haddr))
> +			rc = 32;
> 	}
> 
> 	return rc;
> diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
> index 88212615bf4c..2393e5c106bf 100644
> --- a/net/ipv4/ipconfig.c
> +++ b/net/ipv4/ipconfig.c
> @@ -429,6 +429,8 @@ static int __init ic_defaults(void)
> 			ic_netmask = htonl(IN_CLASSB_NET);
> 		else if (IN_CLASSC(ntohl(ic_myaddr)))
> 			ic_netmask = htonl(IN_CLASSC_NET);
> +		else if (IN_CLASSE(ntohl(ic_myaddr)))
> +			ic_netmask = htonl(IN_CLASSE_NET);
> 		else {
> 			pr_err("IP-Config: Unable to guess netmask for address %pI4\n",
> 			       &ic_myaddr);
> -- 
> 2.20.1
> 
> 
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Cheers,

Kevin D-B

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