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d6b915e29f
linux/net/ipv4
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Florian Westphal d6b915e29f ip_fragment: don't forward defragmented DF packet 
We currently always send fragments without DF bit set.

Thus, given following setup:

mtu1500 - mtu1500:1400 - mtu1400:1280 - mtu1280
   A           R1              R2         B

Where R1 and R2 run linux with netfilter defragmentation/conntrack
enabled, then if Host A sent a fragmented packet _with_ DF set to B, R1
will respond with icmp too big error if one of these fragments exceeded
1400 bytes.

However, if R1 receives fragment sizes 1200 and 100, it would
forward the reassembled packet without refragmenting, i.e.
R2 will send an icmp error in response to a packet that was never sent,
citing mtu that the original sender never exceeded.

The other minor issue is that a refragmentation on R1 will conceal the
MTU of R2-B since refragmentation does not set DF bit on the fragments.

This modifies ip_fragment so that we track largest fragment size seen
both for DF and non-DF packets, and set frag_max_size to the largest
value.

If the DF fragment size is larger or equal to the non-df one, we will
consider the packet a path mtu probe:
We set DF bit on the reassembled skb and also tag it with a new IPCB flag
to force refragmentation even if skb fits outdev mtu.

We will also set DF bit on each fragment in this case.

Joint work with Hannes Frederic Sowa.

Reported-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-27 13:03:31 -04:00
..
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-05-23 01:22:35 -04:00
af_inet.c net: Modify sk_alloc to not reference count the netns of kernel sockets. 2015-05-11 10:50:18 -04:00
ah4.c ipsec: Remove obsolete MAX_AH_AUTH_LEN 2014-09-18 10:54:36 +02:00
arp.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
cipso_ipv4.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
datagram.c net: Save TX flow hash in sock and set in skbuf on xmit 2014-07-07 21:14:21 -07:00
devinet.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
esp4.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
fib_frontend.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-04-06 22:34:15 -04:00
fib_lookup.h ipv4: FIB Local/MAIN table collapse 2015-03-11 16:22:14 -04:00
fib_rules.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
fib_semantics.c ipv4: remove the unnecessary codes in fib_info_hash_move 2015-05-02 22:17:44 -04:00
fib_trie.c ipv4: Fix fib_trie.c build, missing linux/vmalloc.h include. 2015-05-27 00:19:03 -04:00
fou.c fou: avoid missing unlock in failure path 2015-04-16 12:11:19 -04:00
geneve_core.c geneve_core: identify as driver library in modules description 2015-05-13 15:59:13 -04:00
gre_demux.c net: Fix GRE RX to use skb_transport_header for GRE header offset 2014-09-08 15:23:05 -07:00
gre_offload.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
icmp.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
igmp.c net: Export IGMP/MLD message validation code 2015-05-04 14:49:23 -04:00
inet_connection_sock.c tcp: improve REUSEADDR/NOREUSEADDR cohabitation 2015-05-21 18:55:32 -04:00
inet_diag.c tcp: prepare CC get_info() access from getsockopt() 2015-04-29 17:10:38 -04:00
inet_fragment.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
inet_hashtables.c tcp: fix/cleanup inet_ehash_locks_alloc() 2015-05-26 19:48:46 -04:00
inet_lro.c lro: remove dead code 2013-12-29 16:34:25 -05:00
inet_timewait_sock.c tcp/dccp: tw_timer_handler() is static 2015-05-13 15:21:33 -04:00
inetpeer.c inet: remove dead inetpeer sequence code 2014-09-08 16:42:42 -07:00
ip_forward.c ip: reject too-big defragmented DF-skb when forwarding 2015-05-25 00:08:48 -04:00
ip_fragment.c ip_fragment: don't forward defragmented DF packet 2015-05-27 13:03:31 -04:00
ip_gre.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
ip_input.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
ip_options.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
ip_output.c ip_fragment: don't forward defragmented DF packet 2015-05-27 13:03:31 -04:00
ip_sockglue.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
ip_tunnel_core.c ip_tunnel: Report Rx dropped in ip_tunnel_get_stats64 2015-05-14 22:30:54 -04:00
ip_tunnel.c udp_tunnel: Pass UDP socket down through udp_tunnel{, 6}_xmit_skb(). 2015-04-07 15:29:08 -04:00
ip_vti.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
ipcomp.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
ipconfig.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
ipip.c ipip: fix one sparse error 2015-05-17 13:08:29 -04:00
ipmr.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
Kconfig geneve: Rename support library as geneve_core 2015-05-13 15:59:13 -04:00
Makefile geneve: Rename support library as geneve_core 2015-05-13 15:59:13 -04:00
netfilter.c netfilter: Use nf_hook_state in nf_queue_entry. 2015-04-04 12:25:22 -04:00
ping.c ipv4: Missing sk_nulls_node_init() in ping_unhash(). 2015-05-01 22:02:47 -04:00
proc.c tcp: add TCPWinProbe and TCPKeepAlive SNMP counters 2015-05-09 16:42:32 -04:00
protocol.c net: Export inet_offloads and inet6_offloads 2014-09-19 17:15:31 -04:00
raw.c Merge branch 'for-davem' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-04-13 18:18:05 -04:00
route.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-05-23 01:22:35 -04:00
syncookies.c tcp: fix ipv4 mapped request socks 2015-03-25 00:57:48 -04:00
sysctl_net_ipv4.c tcp: tcp_tso_autosize() minimum is one packet 2015-05-26 23:21:29 -04:00
tcp_bic.c tcp: stretch ACK fixes prep 2015-01-28 22:18:37 -08:00
tcp_cong.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-03-20 18:51:09 -04:00
tcp_cubic.c tcp: restore 1.5x per RTT limit to CUBIC cwnd growth in congestion avoidance 2015-03-11 16:51:51 -04:00
tcp_dctcp.c tcp: prepare CC get_info() access from getsockopt() 2015-04-29 17:10:38 -04:00
tcp_diag.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
tcp_fastopen.c tcp: fix a potential deadlock in tcp_get_info() 2015-05-22 13:46:06 -04:00
tcp_highspeed.c tcp: whitespace fixes 2014-09-01 18:12:45 -07:00
tcp_htcp.c tcp: whitespace fixes 2014-09-01 18:12:45 -07:00
tcp_hybla.c tcp: whitespace fixes 2014-09-01 18:12:45 -07:00
tcp_illinois.c tcp: prepare CC get_info() access from getsockopt() 2015-04-29 17:10:38 -04:00
tcp_input.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-05-23 01:22:35 -04:00
tcp_ipv4.c tcp: add tcpi_segs_in and tcpi_segs_out to tcp_info 2015-05-21 23:25:21 -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 memcg: cleanup static keys decrement 2015-02-12 18:54:10 -08:00
tcp_metrics.c tcp: RFC7413 option support for Fast Open client 2015-04-07 18:36:39 -04:00
tcp_minisocks.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-05-23 01:22:35 -04:00
tcp_offload.c tcp: cleanup static functions 2015-02-28 16:56:51 -05:00
tcp_output.c tcp: tcp_tso_autosize() minimum is one packet 2015-05-26 23:21:29 -04:00
tcp_probe.c tcp: whitespace fixes 2014-09-01 18:12:45 -07:00
tcp_scalable.c tcp: stretch ACK fixes prep 2015-01-28 22:18:37 -08:00
tcp_timer.c tcp: introduce tcp_under_memory_pressure() 2015-05-17 22:45:48 -04:00
tcp_vegas.c tcp: prepare CC get_info() access from getsockopt() 2015-04-29 17:10:38 -04:00
tcp_vegas.h tcp: prepare CC get_info() access from getsockopt() 2015-04-29 17:10:38 -04:00
tcp_veno.c tcp: stretch ACK fixes prep 2015-01-28 22:18:37 -08:00
tcp_westwood.c tcp_westwood: fix tcp_westwood_info() 2015-05-05 19:50:09 -04:00
tcp_yeah.c tcp: stretch ACK fixes prep 2015-01-28 22:18:37 -08:00
tcp.c net: make skb_splice_bits more configureable 2015-05-25 00:06:59 -04:00
tunnel4.c
udp_diag.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
udp_impl.h net: Remove iocb argument from sendmsg and recvmsg 2015-03-02 13:06:31 -05:00
udp_offload.c ipv4: coding style: comparison for inequality with NULL 2015-04-03 12:11:15 -04:00
udp_tunnel.c net: Modify sk_alloc to not reference count the netns of kernel sockets. 2015-05-11 10:50:18 -04:00
udp.c net: remove extra newlines 2015-04-07 22:24:37 -04:00
udplite.c net: Eliminate no_check from protosw 2014-05-23 16:28:53 -04:00
xfrm4_input.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
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 ipv4: hash net ptr into fragmentation bucket selection 2015-03-25 14:07:04 -04:00
xfrm4_output.c netfilter: Pass socket pointer down through okfn(). 2015-04-07 15:25:55 -04:00
xfrm4_policy.c ipv4: coding style: comparison for equality with NULL 2015-04-03 12:11:15 -04:00
xfrm4_protocol.c xfrm4: Remove duplicate semicolon 2014-06-30 07:49:47 +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