commit f3594f0a7ea36661d7fd942facd7f31a64245f1a
author Xin Long <lucien.xin@gmail.com> Thu Oct 26 19:19:56 2017 +0800
committer David S. Miller <davem@davemloft.net> Fri Oct 27 23:43:31 2017 +0900
tree 4c6d3e49ce6b519ec208d1ec5cec569181552a08
parent 6d9f0790af8d33476f936ac84a07cac42f808f6c

ipip: only increase err_count for some certain type icmp in ipip_err

t->err_count is used to count the link failure on tunnel and an err
will be reported to user socket in tx path if t->err_count is not 0.
udp socket could even return EHOSTUNREACH to users.

Since commit fd58156e456d ("IPIP: Use ip-tunneling code.") removed
the 'switch check' for icmp type in ipip_err(), err_count would be
increased by the icmp packet with ICMP_EXC_FRAGTIME code. an link
failure would be reported out due to this.

In Jianlin's case, when receiving ICMP_EXC_FRAGTIME a icmp packet,
udp netperf failed with the err:
  send_data: data send error: No route to host (errno 113)

We expect this error reported from tunnel to socket when receiving
some certain type icmp, but not ICMP_EXC_FRAGTIME, ICMP_SR_FAILED
or ICMP_PARAMETERPROB ones.

This patch is to bring 'switch check' for icmp type back to ipip_err
so that it only reports link failure for the right type icmp, just as
in ipgre_err() and ipip6_err().

Fixes: fd58156e456d ("IPIP: Use ip-tunneling code.")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>