This patchset addresses the problem of neighbour
confirmation where received replies from one nexthop
can cause confirmation of different nexthop when using
the same dst. Thanks to YueHaibing <yuehaibing@xxxxxxxxxx>
for tracking the dst->pending_confirm problem.
Sockets can obtain cached output route. Such
routes can be to known nexthop (rt_gateway=IP) or to be
used simultaneously for different nexthop IPs by different
subnet prefixes (nh->nh_scope = RT_SCOPE_HOST, rt_gateway=0).
At first look, there are more problems:
- dst_confirm() sets flag on dst and not on dst->path,
as result, indication is lost when XFRM is used
- DNAT can change the nexthop, so the really used nexthop is
not confirmed
So, the following solution is to avoid using
dst->pending_confirm.
The current dst_confirm() usage is as follows:
Protocols confirming dst on received packets:
- TCP (1 dst per socket)
- SCTP (1 dst per transport)
- CXGB*
Protocols supporting sendmsg with MSG_CONFIRM [ | MSG_PROBE ] to
confirm neighbour:
- UDP IPv4/IPv6
- ICMPv4 PING
- RAW IPv4/IPv6
- L2TP/IPv6
MSG_CONFIRM for other purposes (fix not needed):
- CAN
Sending without locking the socket:
- UDP (when no cork)
- RAW (when hdrincl=1)
Redirects from old to new GW:
- rt6_do_redirect
The patchset includes the following changes:
1. sock: add sk_dst_pending_confirm flag
- used only by TCP with patch 4 to remember the received
indication in sk->sk_dst_pending_confirm
2. net: add dst_pending_confirm flag to skbuff
- skb->dst_pending_confirm will be used by all protocols
in following patches, via skb_{set,get}_dst_pending_confirm
3. sctp: add dst_pending_confirm flag
- SCTP uses per-transport dsts and can not use
sk->sk_dst_pending_confirm like TCP
4. tcp: replace dst_confirm with sk_dst_confirm
5. net: add confirm_neigh method to dst_ops
- IPv4 and IPv6 provision for slow neigh lookups for MSG_PROBE users.
I decided to use neigh lookup only for this case because on
MSG_PROBE the skb may pass MTU checks but it does not reach
the neigh confirmation code. This patch will be used from patch 6.
- xfrm_confirm_neigh: support is incomplete here, only routes with
known nexthops (gateway) are supported because the tunnel address
is slow to obtain. Or there is solution to this problem?
6. net: use dst_confirm_neigh for UDP, RAW, ICMP, L2TP
- dst_confirm conversion for UDP, RAW, ICMP and L2TP/IPv6
- these protocols use MSG_CONFIRM propagated by ip*_append_data
to skb->dst_pending_confirm. sk->sk_dst_pending_confirm is not
used because some sending paths do not lock the socket. For
MSG_PROBE we use the slow lookup (dst_confirm_neigh).
- there are also 2 cases that need the slow lookup:
__ip6_rt_update_pmtu and rt6_do_redirect. I hope
&ipv6_hdr(skb)->saddr is the correct nexthop address to use here.
7. net: pending_confirm is not used anymore
- I failed to understand the CXGB* code, I see dst_confirm()
calls but I'm not sure dst_neigh_output() was called. For now
I just removed the dst->pending_confirm flag and left all
dst_confirm() calls there. Any better idea?
- Now may be old function neigh_output() should be restored
instead of dst_neigh_output?
Julian Anastasov (7):
sock: add sk_dst_pending_confirm flag
net: add dst_pending_confirm flag to skbuff
sctp: add dst_pending_confirm flag
tcp: replace dst_confirm with sk_dst_confirm
net: add confirm_neigh method to dst_ops
net: use dst_confirm_neigh for UDP, RAW, ICMP, L2TP
net: pending_confirm is not used anymore
drivers/net/vrf.c | 5 ++++-
include/linux/skbuff.h | 12 ++++++++++++
include/net/arp.h | 16 ++++++++++++++++
include/net/dst.h | 21 +++++++++------------
include/net/dst_ops.h | 2 ++
include/net/ndisc.h | 17 +++++++++++++++++
include/net/sctp/sctp.h | 6 ++----
include/net/sctp/structs.h | 4 ++++
include/net/sock.h | 26 ++++++++++++++++++++++++++
net/core/dst.c | 1 -
net/core/sock.c | 2 ++
net/ipv4/ip_output.c | 11 ++++++++++-
net/ipv4/ping.c | 3 ++-
net/ipv4/raw.c | 6 +++++-
net/ipv4/route.c | 19 +++++++++++++++++++
net/ipv4/tcp_input.c | 12 +++---------
net/ipv4/tcp_metrics.c | 7 ++-----
net/ipv4/tcp_output.c | 2 ++
net/ipv4/udp.c | 3 ++-
net/ipv6/ip6_output.c | 7 +++++++
net/ipv6/raw.c | 6 +++++-
net/ipv6/route.c | 43 ++++++++++++++++++++++++++++++-------------
net/ipv6/udp.c | 3 ++-
net/l2tp/l2tp_ip6.c | 3 ++-
net/sctp/associola.c | 3 +--
net/sctp/output.c | 10 +++++++++-
net/sctp/outqueue.c | 2 +-
net/sctp/sm_make_chunk.c | 6 ++----
net/sctp/sm_sideeffect.c | 2 +-
net/sctp/socket.c | 4 ++--
net/sctp/transport.c | 17 ++++++++++++++++-
net/xfrm/xfrm_policy.c | 16 ++++++++++++++++
32 files changed, 233 insertions(+), 64 deletions(-)
--
1.9.3
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