linux.git/net/ipv6/ndisc.c, branch v5.16

net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter

2021-11-02T02:57:14+00:00

In most situations the neighbor discovery cache should be cleared on a
NOCARRIER event which is currently done unconditionally. But for wireless
roams the neighbor discovery cache can and should remain intact since
the underlying network has not changed.

This patch introduces a sysctl option ndisc_evict_nocarrier which can
be disabled by a wireless supplicant during a roam. This allows packets
to be sent after a roam immediately without having to wait for
neighbor discovery.

A user reported roughly a 1 second delay after a roam before packets
could be sent out (note, on IPv4). This delay was due to the ARP
cache being cleared. During testing of this same scenario using IPv6
no delay was noticed, but regardless there is no reason to clear
the ndisc cache for wireless roams.

Signed-off-by: James Prestwood 
Reviewed-by: David Ahern 
Signed-off-by: Jakub Kicinski

ipv6: constify dev_addr passing

2021-10-13T16:40:46+00:00

In preparation for netdev->dev_addr being constant
make all relevant arguments in ndisc constant.

Signed-off-by: Jakub Kicinski

ipv6: add IFLA_INET6_RA_MTU to expose mtu value

2021-08-28T00:29:18+00:00

The kernel provides a "/proc/sys/net/ipv6/conf//mtu"
file, which can temporarily record the mtu value of the last
received RA message when the RA mtu value is lower than the
interface mtu, but this proc has following limitations:

(1) when the interface mtu (/sys/class/net//mtu) is
updeated, mtu6 (/proc/sys/net/ipv6/conf//mtu) will
be updated to the value of interface mtu;
(2) mtu6 (/proc/sys/net/ipv6/conf//mtu) only affect
ipv6 connection, and not affect ipv4.

Therefore, when the mtu option is carried in the RA message,
there will be a problem that the user sometimes cannot obtain
RA mtu value correctly by reading mtu6.

After this patch set, if a RA message carries the mtu option,
you can send a netlink msg which nlmsg_type is RTM_GETLINK,
and then by parsing the attribute of IFLA_INET6_RA_MTU to
get the mtu value carried in the RA message received on the
inet6 device. In addition, you can also get a link notification
when ra_mtu is updated so it doesn't have to poll.

In this way, if the MTU values that the device receives from
the network in the PCO IPv4 and the RA IPv6 procedures are
different, the user can obtain the correct ipv6 ra_mtu value
and compare the value of ra_mtu and ipv4 mtu, then the device
can use the lower MTU value for both IPv4 and IPv6.

Signed-off-by: Rocco Yue 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/20210827150412.9267-1-rocco.yue@mediatek.com
Signed-off-by: Jakub Kicinski

net: allow user to set metric on default route learned via Router Advertisement

2021-01-27T02:39:45+00:00

For IPv4, default route is learned via DHCPv4 and user is allowed to change
metric using config etc/network/interfaces. But for IPv6, default route can
be learned via RA, for which, currently a fixed metric value 1024 is used.

Ideally, user should be able to configure metric on default route for IPv6
similar to IPv4. This patch adds sysctl for the same.

Logs:

For IPv4:

Config in etc/network/interfaces:
auto eth0
iface eth0 inet dhcp
    metric 4261413864

IPv4 Kernel Route Table:
$ ip route list
default via 172.21.47.1 dev eth0 metric 4261413864

FRR Table, if a static route is configured:
[In real scenario, it is useful to prefer BGP learned default route over DHCPv4 default route.]
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, P - PIM, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       > - selected route, * - FIB route

S>* 0.0.0.0/0 [20/0] is directly connected, eth0, 00:00:03
K   0.0.0.0/0 [254/1000] via 172.21.47.1, eth0, 6d08h51m

i.e. User can prefer Default Router learned via Routing Protocol in IPv4.
Similar behavior is not possible for IPv6, without this fix.

After fix [for IPv6]:
sudo sysctl -w net.ipv6.conf.eth0.net.ipv6.conf.eth0.ra_defrtr_metric=1996489705

IP monitor: [When IPv6 RA is received]
default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705  pref high

Kernel IPv6 routing table
$ ip -6 route list
default via fe80::be16:65ff:feb3:ce8e dev eth0 proto ra metric 1996489705 expires 21sec hoplimit 64 pref high

FRR Table, if a static route is configured:
[In real scenario, it is useful to prefer BGP learned default route over IPv6 RA default route.]
Codes: K - kernel route, C - connected, S - static, R - RIPng,
       O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table,
       v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
       > - selected route, * - FIB route

S>* ::/0 [20/0] is directly connected, eth0, 00:00:06
K   ::/0 [119/1001] via fe80::xx16:xxxx:feb3:ce8e, eth0, 6d07h43m

If the metric is changed later, the effect will be seen only when next IPv6
RA is received, because the default route must be fully controlled by RA msg.
Below metric is changed from 1996489705 to 1996489704.

$ sudo sysctl -w net.ipv6.conf.eth0.ra_defrtr_metric=1996489704
net.ipv6.conf.eth0.ra_defrtr_metric = 1996489704

IP monitor:
[On next IPv6 RA msg, Kernel deletes prev route and installs new route with updated metric]

Deleted default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705 expires 3sec hoplimit 64 pref high
default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489704 pref high

Signed-off-by: Praveen Chaudhary 
Signed-off-by: Zhenggen Xu 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/20210125214430.24079-1-pchaudhary@linkedin.com
Signed-off-by: Jakub Kicinski

net: Exempt multicast addresses from five-second neighbor lifetime

2020-11-13T22:24:39+00:00

Commit 58956317c8de ("neighbor: Improve garbage collection")
guarantees neighbour table entries a five-second lifetime.  Processes
which make heavy use of multicast can fill the neighour table with
multicast addresses in five seconds.  At that point, neighbour entries
can't be GC-ed because they aren't five seconds old yet, the kernel
log starts to fill up with "neighbor table overflow!" messages, and
sends start to fail.

This patch allows multicast addresses to be thrown out before they've
lived out their five seconds.  This makes room for non-multicast
addresses and makes messages to all addresses more reliable in these
circumstances.

Fixes: 58956317c8de ("neighbor: Improve garbage collection")
Signed-off-by: Jeff Dike 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/20201113015815.31397-1-jdike@akamai.com
Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2020-05-02T00:02:27+00:00

Alexei Starovoitov says:

====================
pull-request: bpf-next 2020-05-01 (v2)

The following pull-request contains BPF updates for your *net-next* tree.

We've added 61 non-merge commits during the last 6 day(s) which contain
a total of 153 files changed, 6739 insertions(+), 3367 deletions(-).

The main changes are:

1) pulled work.sysctl from vfs tree with sysctl bpf changes.

2) bpf_link observability, from Andrii.

3) BTF-defined map in map, from Andrii.

4) asan fixes for selftests, from Andrii.

5) Allow bpf_map_lookup_elem for SOCKMAP and SOCKHASH, from Jakub.

6) production cloudflare classifier as a selftes, from Lorenz.

7) bpf_ktime_get_*_ns() helper improvements, from Maciej.

8) unprivileged bpftool feature probe, from Quentin.

9) BPF_ENABLE_STATS command, from Song.

10) enable bpf_[gs]etsockopt() helpers for sock_ops progs, from Stanislav.

11) enable a bunch of common helpers for cg-device, sysctl, sockopt progs,
 from Stanislav.
====================

Signed-off-by: David S. Miller

net: ipv6: new arg skip_notify to ip6_rt_del

2020-04-28T19:50:37+00:00

Used in subsequent work to skip route delete
notifications on nexthop deletes.

Suggested-by: David Ahern 
Signed-off-by: Roopa Prabhu 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller

sysctl: pass kernel pointers to ->proc_handler

2020-04-27T06:07:40+00:00

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig 
Acked-by: Andrey Ignatov 
Signed-off-by: Al Viro

neigh: support smaller retrans_time settting

2020-04-03T00:55:26+00:00

Currently, we limited the retrans_time to be greater than HZ/2. i.e.
setting retrans_time less than 500ms will not work. This makes the user
unable to achieve a more accurate control for bonding arp fast failover.

Update the sanity check to HZ/100, which is 10ms, to let users have more
ability on the retrans_time control.

v3: sync the behavior with IPv6 and update all the timer handler
v2: use HZ instead of hard code number

Signed-off-by: Hangbin Liu 
Signed-off-by: David S. Miller

ipv6: ndisc: add support for 'PREF64' dns64 prefix identifier

2020-03-27T03:05:58+00:00

This is trivial since we already have support for the entirely
identical (from the kernel's point of view) RDNSS, DNSSL, etc. that
also contain opaque data that needs to be passed down to userspace
for further processing.

As specified in draft-ietf-6man-ra-pref64-09 (while it is still a draft,
it is purely waiting on the RFC Editor for cleanups and publishing):
  PREF64 option contains lifetime and a (up to) 96-bit IPv6 prefix.

The 8-bit identifier of the option type as assigned by the IANA is 38.

Since we lack DNS64/NAT64/CLAT support in kernel at the moment,
thus this option should also be passed on to userland.

See:
  https://tools.ietf.org/html/draft-ietf-6man-ra-pref64-09
  https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xhtml#icmpv6-parameters-5

Cc: Erik Kline 
Cc: Jen Linkova 
Cc: Lorenzo Colitti 
Cc: Michael Haro 
Signed-off-by: Maciej Żenczykowski 
Acked-By: Lorenzo Colitti 
Signed-off-by: David S. Miller