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net: Allow class-e address assignment via ifconfig ioctl

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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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dave Taht 2018-12-11 15:30:34 -08:00 committed by David S. Miller
parent 69d2c86766
commit 65cab850f0
3 changed files with 12 additions and 5 deletions
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10
include/uapi/linux/in.h
View file

@ -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)

5
net/ipv4/devinet.c
View file

@ -952,17 +952,18 @@ 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;

2
net/ipv4/ipconfig.c
View file

@ -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);