target/linux/generic/backport-4.9/095-Allow-class-e-address-assignment-via-ifconfig-ioctl.patch

   1 From 46bf067870156abd61fe24d14c2486d15b8b502c Mon Sep 17 00:00:00 2001
   2 From: Dave Taht <dave@taht.net>
   3 Date: Fri, 14 Dec 2018 18:38:40 +0000
   4 Subject: [PATCH 1/1] Allow class-e address assignment in ifconfig and early
   5  boot
   6
   7 While the linux kernel became mostly "class-e clean" a decade ago,
   8 and most distributions long ago switched to the iproute2 suite
   9 of utilities, which allow class-e (240.0.0.0/4) address assignment,
  10 distributions relying on busybox, toybox and other forms of
  11 ifconfig cannot assign class-e addresses without this kernel patch.
  12
  13 With this patch, also, a boot command line on these addresses is feasible:
  14 (ip=248.0.1.2::248.0.1.1:255.255.255.0).
  15
  16 While CIDR has been obsolete for 2 decades, and a survey of all the
  17 userspace open source code in the world shows most IN_whatever macros
  18 are also obsolete... rather than obsolete CIDR from this ioctl entirely,
  19 this patch merely enables class-e assignment, sanely.
  20
  21 H/T to Vince Fuller and his original patch here:
  22     https://lkml.org/lkml/2008/1/7/370
  23
  24 Signed-off-by: Dave Taht <dave.taht@gmail.com>
  25 Reviewed-by: John Gilmore <gnu@toad.com>
  26 ---
  27  include/uapi/linux/in.h | 8 ++++++--
  28  net/ipv4/devinet.c      | 4 +++-
  29  net/ipv4/ipconfig.c     | 2 ++
  30  3 files changed, 11 insertions(+), 3 deletions(-)
  31
  32 --- a/include/uapi/linux/in.h
  33 +++ b/include/uapi/linux/in.h
  34 @@ -266,8 +266,12 @@ struct sockaddr_in {
  35  #define        IN_MULTICAST(a)         IN_CLASSD(a)
  36  #define IN_MULTICAST_NET       0xF0000000
  37
  38 -#define        IN_EXPERIMENTAL(a)      ((((long int) (a)) & 0xf0000000) == 0xf0000000)
  39 -#define        IN_BADCLASS(a)          IN_EXPERIMENTAL((a))
  40 +#define        IN_BADCLASS(a)          ((((long int) (a) ) == 0xffffffff)
  41 +#define        IN_EXPERIMENTAL(a)      IN_BADCLASS((a))
  42 +
  43 +#define        IN_CLASSE(a)            ((((long int) (a)) & 0xf0000000) == 0xf0000000)
  44 +#define        IN_CLASSE_NET           0xffffffff
  45 +#define        IN_CLASSE_NSHIFT        0
  46
  47  /* Address to accept any incoming messages. */
  48  #define        INADDR_ANY              ((unsigned long int) 0x00000000)
  49 --- a/net/ipv4/devinet.c
  50 +++ b/net/ipv4/devinet.c
  51 @@ -898,7 +898,7 @@ static int inet_abc_len(__be32 addr)
  52  {
  53         int rc = -1;    /* Something else, probably a multicast. */
  54
  55 -       if (ipv4_is_zeronet(addr))
  56 +       if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))
  57                 rc = 0;
  58         else {
  59                 __u32 haddr = ntohl(addr);
  60 @@ -909,6 +909,8 @@ static int inet_abc_len(__be32 addr)
  61                         rc = 16;
  62                 else if (IN_CLASSC(haddr))
  63                         rc = 24;
  64 +               else if (IN_CLASSE(haddr))
  65 +                       rc = 32;
  66         }
  67
  68         return rc;
  69 --- a/net/ipv4/ipconfig.c
  70 +++ b/net/ipv4/ipconfig.c
  71 @@ -455,6 +455,8 @@ static int __init ic_defaults(void)
  72                         ic_netmask = htonl(IN_CLASSB_NET);
  73                 else if (IN_CLASSC(ntohl(ic_myaddr)))
  74                         ic_netmask = htonl(IN_CLASSC_NET);
  75 +               else if (IN_CLASSE(ntohl(ic_myaddr)))
  76 +                       ic_netmask = htonl(IN_CLASSE_NET);
  77                 else {
  78                         pr_err("IP-Config: Unable to guess netmask for address %pI4\n",
  79                                &ic_myaddr);