linux/net/sctp
Marcelo Ricardo Leitner 0ca50d12fe sctp: fix src address selection if using secondary addresses
In short, sctp is likely to incorrectly choose src address if socket is
bound to secondary addresses. This patch fixes it by adding a new check
that checks if such src address belongs to the interface that routing
identified as output.

This is enough to avoid rp_filter drops on remote peer.

Details:

Currently, sctp will do a routing attempt without specifying the src
address and compare the returned value (preferred source) with the
addresses that the socket is bound to. When using secondary addresses,
this will not match.

Then it will try specifying each of the addresses that the socket is
bound to and re-routing, checking if that address is valid as src for
that dst. Thing is, this check alone is weak:

# ip r l
192.168.100.0/24 dev eth1  proto kernel  scope link  src 192.168.100.149
192.168.122.0/24 dev eth0  proto kernel  scope link  src 192.168.122.147

# ip a l
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:15:18:6a brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.147/24 brd 192.168.122.255 scope global dynamic eth0
       valid_lft 2160sec preferred_lft 2160sec
    inet 192.168.122.148/24 scope global secondary eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe15:186a/64 scope link
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:b3:91:46 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.149/24 brd 192.168.100.255 scope global dynamic eth1
       valid_lft 2162sec preferred_lft 2162sec
    inet 192.168.100.148/24 scope global secondary eth1
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:feb3:9146/64 scope link
       valid_lft forever preferred_lft forever
4: ens9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:05:47:ee brd ff:ff:ff:ff:ff:ff
    inet6 fe80::5054:ff:fe05:47ee/64 scope link
       valid_lft forever preferred_lft forever

# ip r g 192.168.100.193 from 192.168.122.148
192.168.100.193 from 192.168.122.148 dev eth1
    cache

Even if you specify an interface:

# ip r g 192.168.100.193 from 192.168.122.148 oif eth1
192.168.100.193 from 192.168.122.148 dev eth1
    cache

Although this would be valid, peers using rp_filter will drop such
packets as their src doesn't match the routes for that interface.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-07-21 00:20:17 -07:00
..
associola.c net: sctp: Deletion of an unnecessary check before the function call "kfree" 2015-02-02 19:29:43 -08:00
auth.c sctp: allow authenticating DATA chunks that are bundled with COOKIE_ECHO 2015-06-12 14:18:20 -07:00
bind_addr.c
chunk.c switch sctp_user_addto_chunk() and sctp_datamsg_from_user() to passing iov_iter 2014-11-24 05:16:40 -05:00
debug.c
endpointola.c
input.c
inqueue.c net: sctp: fix remote memory pressure from excessive queueing 2014-10-14 12:46:22 -04:00
ipv6.c ipv6: Add rt6_get_cookie() function 2015-05-25 13:25:34 -04:00
Kconfig
Makefile
objcnt.c
output.c sctp: Fix race between OOTB responce and route removal 2015-06-29 09:28:42 -07:00
outqueue.c
primitive.c
probe.c
proc.c sctp: replace seq_printf with seq_puts 2014-10-30 19:40:16 -04:00
protocol.c sctp: fix src address selection if using secondary addresses 2015-07-21 00:20:17 -07:00
sm_make_chunk.c net: sctp: fix passing wrong parameter header to param_type2af in sctp_process_param 2015-01-30 17:45:23 -08:00
sm_sideeffect.c
sm_statefuns.c net: sctp: fix remote memory pressure from excessive queueing 2014-10-14 12:46:22 -04:00
sm_statetable.c
socket.c net: Kill sock->sk_protinfo 2015-06-28 16:55:44 -07:00
ssnmap.c
sysctl.c sctp: avoid to repeatedly declare external variables 2015-03-25 11:40:16 -04:00
transport.c
tsnmap.c
ulpevent.c
ulpqueue.c net: introduce SO_INCOMING_CPU 2014-11-11 13:00:06 -05:00