OpenCloudOS-Kernel/net/ipv4
Toke Høiland-Jørgensen 3218274773 icmp: don't send out ICMP messages with a source address of 0.0.0.0
When constructing ICMP response messages, the kernel will try to pick a
suitable source address for the outgoing packet. However, if no IPv4
addresses are configured on the system at all, this will fail and we end up
producing an ICMP message with a source address of 0.0.0.0. This can happen
on a box routing IPv4 traffic via v6 nexthops, for instance.

Since 0.0.0.0 is not generally routable on the internet, there's a good
chance that such ICMP messages will never make it back to the sender of the
original packet that the ICMP message was sent in response to. This, in
turn, can create connectivity and PMTUd problems for senders. Fortunately,
RFC7600 reserves a dummy address to be used as a source for ICMP
messages (192.0.0.8/32), so let's teach the kernel to substitute that
address as a last resort if the regular source address selection procedure
fails.

Below is a quick example reproducing this issue with network namespaces:

ip netns add ns0
ip l add type veth peer netns ns0
ip l set dev veth0 up
ip a add 10.0.0.1/24 dev veth0
ip a add fc00:dead:cafe:42::1/64 dev veth0
ip r add 10.1.0.0/24 via inet6 fc00:dead:cafe:42::2
ip -n ns0 l set dev veth0 up
ip -n ns0 a add fc00:dead:cafe:42::2/64 dev veth0
ip -n ns0 r add 10.0.0.0/24 via inet6 fc00:dead:cafe:42::1
ip netns exec ns0 sysctl -w net.ipv4.icmp_ratelimit=0
ip netns exec ns0 sysctl -w net.ipv4.ip_forward=1
tcpdump -tpni veth0 -c 2 icmp &
ping -w 1 10.1.0.1 > /dev/null
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on veth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
IP 10.0.0.1 > 10.1.0.1: ICMP echo request, id 29, seq 1, length 64
IP 0.0.0.0 > 10.0.0.1: ICMP net 10.1.0.1 unreachable, length 92
2 packets captured
2 packets received by filter
0 packets dropped by kernel

With this patch the above capture changes to:
IP 10.0.0.1 > 10.1.0.1: ICMP echo request, id 31127, seq 1, length 64
IP 192.0.0.8 > 10.0.0.1: ICMP net 10.1.0.1 unreachable, length 92

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: Juliusz Chroboczek <jch@irif.fr>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-06-18 12:13:24 -07:00
..
bpfilter net: Revert "net: optimize the sockptr_t for unified kernel/user address spaces" 2020-08-10 12:06:44 -07:00
netfilter netfilter: arptables: use pernet ops struct during unregister 2021-05-03 23:04:01 +02:00
Kconfig net: ipv4: remove duplicate "the the" phrase in Kconfig text 2020-08-18 16:02:16 -07:00
Makefile bpf: Clean up sockmap related Kconfigs 2021-02-26 12:28:03 -08:00
af_inet.c inet: annotate data race in inet_send_prepare() and inet_dgram_connect() 2021-06-09 13:59:53 -07:00
ah4.c xfrm: Use actual socket sk instead of skb socket for xfrm_output_resume 2021-03-03 09:32:52 +01:00
arp.c net: Exempt multicast addresses from five-second neighbor lifetime 2020-11-13 14:24:39 -08:00
bpf_tcp_ca.c bpf: Limit static tcp-cc functions in the .BTF_ids list to x86 2021-05-11 23:23:07 +02:00
cipso_ipv4.c net: ipv4: fix memory leak in netlbl_cipsov4_add_std 2021-06-08 11:36:04 -07:00
datagram.c inet: stop leaking jiffies on the wire 2019-11-01 14:57:52 -07:00
devinet.c net: ipv4: Remove unneed BUG() function 2021-06-08 11:36:48 -07:00
esp4.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2021-04-14 13:15:12 -07:00
esp4_offload.c xfrm: Provide private skb extensions for segmented and hw offloaded ESP packets 2021-03-29 09:14:12 +02:00
fib_frontend.c ipv4: Ignore ECN bits for fib lookups in fib_compute_spec_dst() 2020-12-28 14:44:32 -08:00
fib_lookup.h IPv4: Add "offload failed" indication to routes 2021-02-08 16:47:03 -08:00
fib_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_rules.c fib: use indirect call wrappers in the most common fib_rules_ops 2020-07-28 17:42:31 -07:00
fib_semantics.c IPv4: Add "offload failed" indication to routes 2021-02-08 16:47:03 -08:00
fib_trie.c IPv4: Extend 'fib_notify_on_flag_change' sysctl 2021-02-08 16:47:03 -08:00
fou.c genetlink: move to smaller ops wherever possible 2020-10-02 19:11:11 -07:00
gre_demux.c erspan: fix version 1 check in gre_parse_header() 2020-12-28 15:00:00 -08:00
gre_offload.c ip_gre: add csum offload support for gre header 2021-01-29 20:39:14 -08:00
icmp.c icmp: don't send out ICMP messages with a source address of 0.0.0.0 2021-06-18 12:13:24 -07:00
igmp.c net: ipv4: fix memory leak in ip_mc_add1_src 2021-06-16 12:41:01 -07:00
inet_connection_sock.c tcp: relookup sock for RST+ACK packets handled by obsolete req sock 2021-03-15 14:34:29 -07:00
inet_diag.c inet_diag: Fix error path to cancel the meseage in inet_req_diag_fill() 2020-11-17 16:08:36 -08:00
inet_fragment.c inet: frags: batch fqdir destroy works 2020-12-12 15:08:54 -08:00
inet_hashtables.c tcp: add some entropy in __inet_hash_connect() 2021-02-11 13:13:05 -08:00
inet_timewait_sock.c net: Use generic ns_common::count 2020-08-19 14:06:36 +02:00
inetpeer.c inetpeer: use div64_ul() and clamp_val() calculate inet_peer_threshold 2021-03-01 13:32:12 -08:00
ip_forward.c ipv4: Revert removal of rt_uses_gateway 2019-09-20 18:23:33 -07:00
ip_fragment.c
ip_gre.c ipv4/ipv6: switch to dev_get_tstats64 2020-11-09 17:50:28 -08:00
ip_input.c net: use indirect call helpers for dst_input 2021-02-03 14:51:39 -08:00
ip_options.c net: clean up codestyle for net/ipv4 2020-08-25 06:28:02 -07:00
ip_output.c ipv4: ip_output.c: Couple of typo fixes 2021-03-28 17:31:13 -07:00
ip_sockglue.c net: Remove duplicated midx check against 0 2020-08-25 06:23:59 -07:00
ip_tunnel.c net: always use icmp{,v6}_ndo_send from ndo_start_xmit 2021-03-01 13:11:35 -08:00
ip_tunnel_core.c net: ip_tunnel: clean up endianness conversions 2021-01-08 19:25:35 -08:00
ip_vti.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec 2021-03-31 14:37:51 -07:00
ipcomp.c ipcomp: assign if_id to child tunnel from parent tunnel 2020-07-09 12:55:37 +02:00
ipconfig.c net: ipconfig: Don't override command-line hostnames or domains 2021-06-02 13:27:03 -07:00
ipip.c ipv4/ipv6: switch to dev_get_tstats64 2020-11-09 17:50:28 -08:00
ipmr.c ipmr: Use full VIF ID in netlink cache reports 2020-09-10 12:25:51 -07:00
ipmr_base.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
metrics.c treewide: rename nla_strlcpy to nla_strscpy. 2020-11-16 08:08:54 -08:00
netfilter.c netfilter: Dissect flow after packet mangling 2021-04-18 22:04:16 +02:00
netlink.c
nexthop.c nexthop: Restart nexthop dump based on last dumped nexthop identifier 2021-04-19 15:20:34 -07:00
ping.c ping: Check return value of function 'ping_queue_rcv_skb' 2021-06-10 13:44:55 -07:00
proc.c net: proc: speedup /proc/net/netstat 2021-01-29 20:59:53 -08:00
protocol.c
raw.c lsm,selinux: pass flowi_common instead of flowi to the LSM hooks 2020-11-23 18:36:21 -05:00
raw_diag.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-03-12 22:34:48 -07:00
route.c ipv4: Fix device used for dst_alloc with local routes 2021-06-14 12:30:53 -07:00
syncookies.c selinux/stable-5.11 PR 20201214 2020-12-16 11:01:04 -08:00
sysctl_net_ipv4.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-04-17 11:08:07 -07:00
tcp.c tcp: Specify cmsgbuf is user pointer for receive zerocopy. 2021-05-06 18:05:35 -07:00
tcp_bbr.c tcp: only postpone PROBE_RTT if RTT is < current min_rtt estimate 2020-11-17 11:03:22 -08:00
tcp_bic.c tcp: fix stretch ACK bugs in BIC 2020-03-16 18:26:54 -07:00
tcp_bpf.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-04-25 18:02:32 -07:00
tcp_cdg.c
tcp_cong.c net: Only allow init netns to set default tcp cong to a restricted algo 2021-05-04 11:58:28 -07:00
tcp_cubic.c tcp: Rename bictcp function prefix to cubictcp 2021-03-26 20:41:51 -07:00
tcp_dctcp.c
tcp_dctcp.h
tcp_diag.c inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data 2020-02-27 18:50:19 -08:00
tcp_fastopen.c bpf: tcp: Add bpf_skops_established() 2020-08-24 14:35:00 -07:00
tcp_highspeed.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_htcp.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_hybla.c
tcp_illinois.c
tcp_input.c tcp: consider using standard rtx logic in tcp_rcv_fastopen_synack() 2021-03-11 18:35:31 -08:00
tcp_ipv4.c mptcp: add mptcp reset option support 2021-04-02 14:21:50 -07:00
tcp_lp.c ipv4: tcp_lp.c: Couple of typo fixes 2021-03-28 17:31:13 -07:00
tcp_metrics.c fixes-v5.11 2020-12-14 16:40:27 -08:00
tcp_minisocks.c tcp: relookup sock for RST+ACK packets handled by obsolete req sock 2021-03-15 14:34:29 -07:00
tcp_nv.c
tcp_offload.c
tcp_output.c tcp: remove obsolete check in __tcp_retransmit_skb() 2021-03-11 18:35:31 -08:00
tcp_rate.c
tcp_recovery.c tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN 2021-01-23 21:33:01 -08:00
tcp_scalable.c net: ipv4: delete repeated words 2020-08-24 17:31:20 -07:00
tcp_timer.c tcp: make TCP_USER_TIMEOUT accurate for zero window probes 2021-01-23 19:32:51 -08:00
tcp_ulp.c bpf: sockmap: Only check ULP for TCP sockets 2020-03-09 22:34:58 +01:00
tcp_vegas.c tcp: use semicolons rather than commas to separate statements 2020-10-13 17:11:52 -07:00
tcp_vegas.h
tcp_veno.c Replace HTTP links with HTTPS ones: IPv* 2020-07-06 13:23:03 -07:00
tcp_westwood.c
tcp_yeah.c tcp: fix stretch ACK bugs in Yeah 2020-03-16 18:26:55 -07:00
tunnel4.c tunnel4: add cb_handler to struct xfrm_tunnel 2020-07-09 12:51:36 +02:00
udp.c udp: fix race between close() and udp_abort() 2021-06-09 14:08:41 -07:00
udp_bpf.c skmsg: Pass psock pointer to ->psock_update_sk_prot() 2021-04-12 17:34:27 +02:00
udp_diag.c net: udp: remove redundant initialization in udp_dump_one 2020-11-09 16:42:49 -08:00
udp_impl.h net: pass a sockptr_t into ->setsockopt 2020-07-24 15:41:54 -07:00
udp_offload.c udp: properly complete L4 GRO over UDP tunnel packet 2021-03-30 17:06:49 -07:00
udp_tunnel_core.c udp_tunnel: reshuffle NETIF_F_RX_UDP_TUNNEL_PORT checks 2021-01-07 12:53:29 -08:00
udp_tunnel_nic.c udp_tunnel: add the ability to share port tables 2020-09-28 12:50:12 -07:00
udp_tunnel_stub.c udp_tunnel: add central NIC RX port offload infrastructure 2020-07-10 13:54:00 -07:00
udplite.c net/ipv4: remove compat_ip_{get,set}sockopt 2020-07-19 18:16:41 -07:00
xfrm4_input.c xfrm: state: remove extract_input indirection from xfrm_state_afinfo 2020-05-06 09:40:08 +02:00
xfrm4_output.c xfrm: fix unused variable warning if CONFIG_NETFILTER=n 2020-05-11 15:12:27 +02:00
xfrm4_policy.c net: add bool confirm_neigh parameter for dst_ops.update_pmtu 2019-12-24 22:28:54 -08:00
xfrm4_protocol.c xfrm: add route lookup to xfrm4_rcv_encap 2019-12-09 09:59:07 +01:00
xfrm4_state.c xfrm: remove output_finish indirection from xfrm_state_afinfo 2020-05-06 09:40:08 +02:00
xfrm4_tunnel.c xfrm: interface: fix the priorities for ipip and ipv6 tunnels 2020-10-09 12:29:48 +02:00