On 5/25/20 5:54 PM, David Miller wrote:
> From: Eric Dumazet <eduma...@google.com>
> Date: Sun, 24 May 2020 11:00:02 -0700
>
>> Unpriv users can use traceroute over plain UDP sockets, but not TCP ones.
>>
>> $ traceroute -Mtcp 8.8.8.8
>> You do not have enough privileges to use this traceroute method.
>>
>> $ traceroute -n -Mudp 8.8.8.8
>> traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 60 byte packets
>> 1 192.168.86.1 3.631 ms 3.512 ms 3.405 ms
>> 2 10.1.10.1 4.183 ms 4.125 ms 4.072 ms
>> 3 96.120.88.125 20.621 ms 19.462 ms 20.553 ms
>> 4 96.110.177.65 24.271 ms 25.351 ms 25.250 ms
>> 5 69.139.199.197 44.492 ms 43.075 ms 44.346 ms
>> 6 68.86.143.93 27.969 ms 25.184 ms 25.092 ms
>> 7 96.112.146.18 25.323 ms 96.112.146.22 25.583 ms 96.112.146.26 24.502
>> ms
>> 8 72.14.239.204 24.405 ms 74.125.37.224 16.326 ms 17.194 ms
>> 9 209.85.251.9 18.154 ms 209.85.247.55 14.449 ms 209.85.251.9 26.296
>> ms^C
>>
>> We can easily support traceroute over TCP, by queueing an error message
>> into socket error queue.
>>
>> Note that applications need to set IP_RECVERR/IPV6_RECVERR option to
>> enable this feature, and that the error message is only queued
>> while in SYN_SNT state.
>>
>> socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
>> setsockopt(3, SOL_IPV6, IPV6_RECVERR, [1], 4) = 0
>> setsockopt(3, SOL_SOCKET, SO_TIMESTAMP_OLD, [1], 4) = 0
>> setsockopt(3, SOL_IPV6, IPV6_UNICAST_HOPS, [5], 4) = 0
>> connect(3, {sa_family=AF_INET6, sin6_port=htons(8787),
>> sin6_flowinfo=htonl(0),
>> inet_pton(AF_INET6, "2002:a05:6608:297::", &sin6_addr),
>> sin6_scope_id=0}, 28) = -1 EHOSTUNREACH (No route to host)
>> recvmsg(3, {msg_name={sa_family=AF_INET6, sin6_port=htons(8787),
>> sin6_flowinfo=htonl(0),
>> inet_pton(AF_INET6, "2002:a05:6608:297::", &sin6_addr),
>> sin6_scope_id=0},
>> msg_namelen=1024->28,
>> msg_iov=[{iov_base="`\r\337\320\0004\6\1&\7\370\260\200\231\16\27\0\0\0\0\0\0\0\0
>> \2\n\5f\10\2\227"..., iov_len=1024}],
>> msg_iovlen=1, msg_control=[{cmsg_len=32, cmsg_level=SOL_SOCKET,
>> cmsg_type=SO_TIMESTAMP_OLD, cmsg_data={tv_sec=1590340680, tv_usec=272424}},
>> {cmsg_len=60, cmsg_level=SOL_IPV6,
>> cmsg_type=IPV6_RECVERR}],
>> msg_controllen=96, msg_flags=MSG_ERRQUEUE}, MSG_ERRQUEUE) = 144
>>
>> Suggested-by: Maciej Żenczykowski <m...@google.com
>> Signed-off-by: Eric Dumazet <eduma...@google.com>
>
> Applied, thanks Eric.
>
I will send a fix, it appears tcp_v4_err() has two sk_buff variables,
one named icmp_skb, and another one :/
