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- From 46bf067870156abd61fe24d14c2486d15b8b502c Mon Sep 17 00:00:00 2001
- From: Dave Taht <dave@taht.net>
- Date: Fri, 14 Dec 2018 18:38:40 +0000
- Subject: [PATCH 1/1] Allow class-e address assignment in ifconfig and early
- boot
- While the linux kernel became mostly "class-e clean" a decade ago,
- and 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.
- With this patch, also, a boot command line on these addresses is feasible:
- (ip=248.0.1.2::248.0.1.1:255.255.255.0).
- While CIDR has been obsolete for 2 decades, and a survey of all the
- userspace open source code in the world shows most IN_whatever macros
- are also obsolete... rather than obsolete CIDR from this ioctl entirely,
- this patch merely enables class-e assignment, sanely.
- H/T to Vince Fuller and his original patch here:
- https://lkml.org/lkml/2008/1/7/370
- Signed-off-by: Dave Taht <dave.taht@gmail.com>
- Reviewed-by: John Gilmore <gnu@toad.com>
- ---
- include/uapi/linux/in.h | 8 ++++++--
- net/ipv4/devinet.c | 4 +++-
- net/ipv4/ipconfig.c | 2 ++
- 3 files changed, 11 insertions(+), 3 deletions(-)
- --- a/include/uapi/linux/in.h
- +++ b/include/uapi/linux/in.h
- @@ -268,8 +268,12 @@ struct sockaddr_in {
- #define IN_MULTICAST(a) IN_CLASSD(a)
- #define IN_MULTICAST_NET 0xF0000000
-
- -#define IN_EXPERIMENTAL(a) ((((long int) (a)) & 0xf0000000) == 0xf0000000)
- -#define IN_BADCLASS(a) IN_EXPERIMENTAL((a))
- +#define IN_BADCLASS(a) (((long int) (a) ) == (long int)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)
- --- a/net/ipv4/devinet.c
- +++ b/net/ipv4/devinet.c
- @@ -935,7 +935,7 @@ 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);
- @@ -946,6 +946,8 @@ static int inet_abc_len(__be32 addr)
- rc = 16;
- else if (IN_CLASSC(haddr))
- rc = 24;
- + else if (IN_CLASSE(haddr))
- + rc = 32;
- }
-
- return rc;
- --- a/net/ipv4/ipconfig.c
- +++ b/net/ipv4/ipconfig.c
- @@ -457,6 +457,8 @@ 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);
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