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linux-sg2042/net/ipv4
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Edward Allcutt 68b7107b62 ipv4: icmp: Fix pMTU handling for rare case 
Some older router implementations still send Fragmentation Needed
errors with the Next-Hop MTU field set to zero. This is explicitly
described as an eventuality that hosts must deal with by the
standard (RFC 1191) since older standards specified that those
bits must be zero.

Linux had a generic (for all of IPv4) implementation of the algorithm
described in the RFC for searching a list of MTU plateaus for a good
value. Commit 46517008e1 ("ipv4: Kill ip_rt_frag_needed().")
removed this as part of the changes to remove the routing cache.
Subsequently any Fragmentation Needed packet with a zero Next-Hop
MTU has been discarded without being passed to the per-protocol
handlers or notifying userspace for raw sockets.

When there is a router which does not implement RFC 1191 on an
MTU limited path then this results in stalled connections since
large packets are discarded and the local protocols are not
notified so they never attempt to lower the pMTU.

One example I have seen is an OpenBSD router terminating IPSec
tunnels. It's worth pointing out that this case is distinct from
the BSD 4.2 bug which incorrectly calculated the Next-Hop MTU
since the commit in question dismissed that as a valid concern.

All of the per-protocols handlers implement the simple approach from
RFC 1191 of immediately falling back to the minimum value. Although
this is sub-optimal it is vastly preferable to connections hanging
indefinitely.

Remove the Next-Hop MTU != 0 check and allow such packets
to follow the normal path.

Fixes: 46517008e1 ("ipv4: Kill ip_rt_frag_needed().")
Signed-off-by: Edward Allcutt <edward.allcutt@openmarket.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 		2014-07-07 17:22:57 -07:00
..
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2014-05-30 17:54:47 -07:00
Kconfig net: neighbour: Remove CONFIG_ARPD 2013-09-03 21:41:43 -04:00
Makefile xfrm4: Add IPsec protocol multiplexer 2014-02-25 07:04:16 +01:00
af_inet.c gre: Call gso_make_checksum 2014-06-04 22:46:38 -07:00
ah4.c ah4: Use the IPsec protocol multiplexer API 2014-02-25 07:04:17 +01:00
arp.c ipv4: arp: update neighbour address when a gratuitous arp is received and arp_accept is set 2014-01-02 00:08:38 -05:00
cipso_ipv4.c ipv4: ERROR: code indent should use tabs where possible 2013-12-26 13:43:21 -05:00
datagram.c ipv4: fix a race in ip4_datagram_release_cb() 2014-06-11 15:39:18 -07:00
devinet.c ipv4: minor spelling fix 2014-05-18 21:10:29 -04:00
esp4.c esp4: Use the IPsec protocol multiplexer API 2014-02-25 07:04:17 +01:00
fib_frontend.c ipv4, fib: pass LOOPBACK_IFINDEX instead of 0 to flowi4_iif 2014-04-16 15:05:11 -04:00
fib_lookup.h ipv4: make fib_detect_death static 2013-12-28 17:01:46 -05:00
fib_rules.c inet: fix NULL pointer Oops in fib(6)_rule_suppress 2013-12-10 17:54:23 -05:00
fib_semantics.c ipv4: fib_semantics: increment fib_info_cnt after fib_info allocation 2014-05-07 17:14:32 -04:00
fib_trie.c net: Revert "fib_trie: use seq_file_net rather than seq->private" 2014-06-04 15:11:41 -07:00
gre_demux.c gre: Call gso_make_checksum 2014-06-04 22:46:38 -07:00
gre_offload.c net: Save software checksum complete 2014-06-11 15:46:13 -07:00
icmp.c ipv4: icmp: Fix pMTU handling for rare case 2014-07-07 17:22:57 -07:00
igmp.c inetpeer: get rid of ip_id_count 2014-06-02 11:00:41 -07:00
inet_connection_sock.c ipv4: make ip_local_reserved_ports per netns 2014-05-14 15:31:45 -04:00
inet_diag.c inet_diag: fix inet_diag_dump_icsk() to use correct state for timewait sockets 2014-01-13 22:35:46 -08:00
inet_fragment.c inet: frag: make sure forced eviction removes all frags 2014-03-06 15:28:45 -05:00
inet_hashtables.c net: Use a more standard macro for INET_ADDR_COOKIE 2014-05-14 16:07:23 -04:00
inet_lro.c lro: remove dead code 2013-12-29 16:34:25 -05:00
inet_timewait_sock.c tcp/dccp: remove twchain 2013-10-08 23:19:24 -04:00
inetpeer.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
ip_forward.c net: rename local_df to ignore_df 2014-05-12 14:03:41 -04:00
ip_fragment.c ipv4: fix "conntrack zones" support for defrag user check in ip_expire 2014-05-05 16:02:59 +02:00
ip_gre.c gre: allow changing mac address when device is up 2014-06-10 22:46:42 -07:00
ip_input.c net: Fix memory leak if TPROXY used with TCP early demux 2014-01-27 16:22:11 -08:00
ip_options.c ipv4: Use predefined value for readability 2014-04-28 13:28:43 -04:00
ip_output.c inetpeer: get rid of ip_id_count 2014-06-02 11:00:41 -07:00
ip_sockglue.c ipv4: yet another new IP_MTU_DISCOVER option IP_PMTUDISC_OMIT 2014-02-26 15:51:00 -05:00
ip_tunnel.c ipv4: fix dst race in sk_dst_get() 2014-06-25 17:41:44 -07:00
ip_tunnel_core.c net: Support for multiple checksums with gso 2014-06-04 22:46:38 -07:00
ip_vti.c ip_vti: Fix 'ip tunnel add' with 'key' parameters 2014-06-11 00:30:52 -07:00
ipcomp.c ipcomp4: Use the IPsec protocol multiplexer API 2014-02-25 07:04:17 +01:00
ipconfig.c ipv4: ipconfig.c: add parentheses in an if statement 2014-02-14 00:14:23 -05:00
ipip.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-06-11 16:02:55 -07:00
ipmr.c inetpeer: get rid of ip_id_count 2014-06-02 11:00:41 -07:00
netfilter.c netfilter: remove double colon 2014-02-19 11:41:25 +01:00
ping.c ping: move ping_group_range out of CONFIG_SYSCTL 2014-05-08 22:50:47 -04:00
proc.c net: clean up snmp stats code 2014-05-07 16:06:05 -04:00
protocol.c net: remove outdated comment for ipv4 and ipv6 protocol handler 2013-11-28 18:47:51 -05:00
raw.c inetpeer: get rid of ip_id_count 2014-06-02 11:00:41 -07:00
route.c ipv4: irq safe sk_dst_[re]set() and ipv4_sk_update_pmtu() fix 2014-06-30 23:40:58 -07:00
syncookies.c net: support marking accepting TCP sockets 2014-05-13 18:35:09 -04:00
sysctl_net_ipv4.c ipv4: make ip_local_reserved_ports per netns 2014-05-14 15:31:45 -04:00
tcp.c tcp: Fix divide by zero when pushing during tcp-repair 2014-07-02 18:21:03 -07:00
tcp_bic.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_cong.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_cubic.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-05-12 13:19:14 -04:00
tcp_diag.c inet_diag: Rename inet_diag_req into inet_diag_req_v2 2012-01-11 12:56:06 -08:00
tcp_fastopen.c tcp: remove unnecessary tcp_sk assignment. 2014-06-16 21:35:00 -07:00
tcp_highspeed.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_htcp.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_hybla.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_illinois.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_input.c tcp: fix tcp_match_skb_to_sack() for unaligned SACK at end of an skb 2014-06-19 20:50:49 -07:00
tcp_ipv4.c net: support marking accepting TCP sockets 2014-05-13 18:35:09 -04:00
tcp_lp.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_memcontrol.c cgroup: replace cftype->trigger() with cftype->write() 2014-05-13 12:16:21 -04:00
tcp_metrics.c net: use the new API kvfree() 2014-06-05 00:49:51 -07:00
tcp_minisocks.c tcp: use tcp_v4_send_synack on first SYN-ACK 2014-05-13 17:53:02 -04:00
tcp_offload.c gre: Call gso_make_checksum 2014-06-04 22:46:38 -07:00
tcp_output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
tcp_probe.c tcp: switch rtt estimations to usec resolution 2014-02-26 17:08:40 -05:00
tcp_scalable.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_timer.c tcp: snmp stats for Fast Open, SYN rtx, and data pkts 2014-03-03 15:58:03 -05:00
tcp_vegas.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_vegas.h net: ipv4/ipv6: Remove extern from function prototypes 2013-10-19 19:12:11 -04:00
tcp_veno.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tcp_westwood.c tcp: remove unused min_cwnd member of tcp_congestion_ops 2014-02-13 18:22:34 -05:00
tcp_yeah.c tcp: remove in_flight parameter from cong_avoid() methods 2014-05-03 19:23:07 -04:00
tunnel4.c net: Convert printks to pr_<level> 2012-03-11 23:42:51 -07:00
udp.c udp: Add MIB counters for rcvbuferrors 2014-06-27 00:20:55 -07:00
udp_diag.c netlink: rename ssk to sk in struct netlink_skb_params 2013-04-19 14:57:56 -04:00
udp_impl.h net: ipv4/ipv6: Remove extern from function prototypes 2013-10-19 19:12:11 -04:00
udp_offload.c net: Add skb_gro_postpull_rcsum to udp and vxlan 2014-06-11 15:46:13 -07:00
udplite.c net: Eliminate no_check from protosw 2014-05-23 16:28:53 -04:00
xfrm4_input.c xfrm4: Add IPsec protocol multiplexer 2014-02-25 07:04:16 +01:00
xfrm4_mode_beet.c ipv4: ERROR: code indent should use tabs where possible 2013-12-26 13:43:21 -05:00
xfrm4_mode_transport.c
…
xfrm4_mode_tunnel.c inetpeer: get rid of ip_id_count 2014-06-02 11:00:41 -07:00
xfrm4_output.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-05-24 00:32:30 -04:00
xfrm4_policy.c xfrm: Introduce xfrm_input_afinfo to access the the callbacks properly 2014-03-14 07:28:07 +01:00
xfrm4_protocol.c xfrm4: Properly handle unsupported protocols 2014-04-29 08:41:12 +02:00
xfrm4_state.c inet: make no_pmtu_disc per namespace and kill ipv4_config 2013-12-18 16:58:20 -05:00
xfrm4_tunnel.c sit: add IPv4 over IPv4 support 2013-05-31 17:19:05 -07:00