releases/4.4.73/net-fix-proc-net-arp-for-ax.25.patch

   1 From foo@baz Thu Jun 15 11:13:01 CEST 2017
   2 From: Ralf Baechle <ralf@linux-mips.org>
   3 Date: Tue, 23 May 2017 21:53:37 -0400
   4 Subject: NET: Fix /proc/net/arp for AX.25
   5
   6 From: Ralf Baechle <ralf@linux-mips.org>
   7
   8
   9 [ Upstream commit 4872e57c812dd312bf8193b5933fa60585cda42f ]
  10
  11 When sending ARP requests over AX.25 links the hwaddress in the neighbour
  12 cache are not getting initialized.  For such an incomplete arp entry
  13 ax2asc2 will generate an empty string resulting in /proc/net/arp output
  14 like the following:
  15
  16 $ cat /proc/net/arp
  17 IP address       HW type     Flags       HW address            Mask     Device
  18 192.168.122.1    0x1         0x2         52:54:00:00:5d:5f     *        ens3
  19 172.20.1.99      0x3         0x0              *        bpq0
  20
  21 The missing field will confuse the procfs parsing of arp(8) resulting in
  22 incorrect output for the device such as the following:
  23
  24 $ arp
  25 Address                  HWtype  HWaddress           Flags Mask            Iface
  26 gateway                  ether   52:54:00:00:5d:5f   C                     ens3
  27 172.20.1.99                      (incomplete)                              ens3
  28
  29 This changes the content of /proc/net/arp to:
  30
  31 $ cat /proc/net/arp
  32 IP address       HW type     Flags       HW address            Mask     Device
  33 172.20.1.99      0x3         0x0         *                     *        bpq0
  34 192.168.122.1    0x1         0x2         52:54:00:00:5d:5f     *        ens3
  35
  36 To do so it change ax2asc to put the string "*" in buf for a NULL address
  37 argument.  Finally the HW address field is left aligned in a 17 character
  38 field (the length of an ethernet HW address in the usual hex notation) for
  39 readability.
  40
  41 Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
  42 Signed-off-by: David S. Miller <davem@davemloft.net>
  43 Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
  44 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  45 ---
  46  net/ipv4/arp.c |   12 ++++++------
  47  1 file changed, 6 insertions(+), 6 deletions(-)
  48
  49 --- a/net/ipv4/arp.c
  50 +++ b/net/ipv4/arp.c
  51 @@ -1250,7 +1250,7 @@ void __init arp_init(void)
  52  /*
  53   *     ax25 -> ASCII conversion
  54   */
  55 -static char *ax2asc2(ax25_address *a, char *buf)
  56 +static void ax2asc2(ax25_address *a, char *buf)
  57  {
  58         char c, *s;
  59         int n;
  60 @@ -1272,10 +1272,10 @@ static char *ax2asc2(ax25_address *a, ch
  61         *s++ = n + '0';
  62         *s++ = '\0';
  63
  64 -       if (*buf == '\0' || *buf == '-')
  65 -               return "*";
  66 -
  67 -       return buf;
  68 +       if (*buf == '\0' || *buf == '-') {
  69 +               buf[0] = '*';
  70 +               buf[1] = '\0';
  71 +       }
  72  }
  73  #endif /* CONFIG_AX25 */
  74
  75 @@ -1309,7 +1309,7 @@ static void arp_format_neigh_entry(struc
  76         }
  77  #endif
  78         sprintf(tbuf, "%pI4", n->primary_key);
  79 -       seq_printf(seq, "%-16s 0x%-10x0x%-10x%s     *        %s\n",
  80 +       seq_printf(seq, "%-16s 0x%-10x0x%-10x%-17s     *        %s\n",
  81                    tbuf, hatype, arp_state_to_flags(n), hbuffer, dev->name);
  82         read_unlock(&n->lock);
  83  }