net: change accept_ra_min_rtr_lft to affect all RA lifetimes

accept_ra_min_rtr_lft only considered the lifetime of the default route
and discarded entire RAs accordingly.

This change renames accept_ra_min_rtr_lft to accept_ra_min_lft, and
applies the value to individual RA sections; in particular, router
lifetime, PIO preferred lifetime, and RIO lifetime. If any of those
lifetimes are lower than the configured value, the specific RA section
is ignored.

In order for the sysctl to be useful to Android, it should really apply
to all lifetimes in the RA, since that is what determines the minimum
frequency at which RAs must be processed by the kernel. Android uses
hardware offloads to drop RAs for a fraction of the minimum of all
lifetimes present in the RA (some networks have very frequent RAs (5s)
with high lifetimes (2h)). Despite this, we have encountered networks
that set the router lifetime to 30s which results in very frequent CPU
wakeups. Instead of disabling IPv6 (and dropping IPv6 ethertype in the
WiFi firmware) entirely on such networks, it seems better to ignore the
misconfigured routers while still processing RAs from other IPv6 routers
on the same network (i.e. to support IoT applications).

The previous implementation dropped the entire RA based on router
lifetime. This turned out to be hard to expand to the other lifetimes
present in the RA in a consistent manner; dropping the entire RA based
on RIO/PIO lifetimes would essentially require parsing the whole thing
twice.

Fixes: 1671bcfd76fd ("net: add sysctl accept_ra_min_rtr_lft")
Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Patrick Rohr <prohr@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230726230701.919212-1-prohr@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: add sysctl accept_ra_min_rtr_lft

This change adds a new sysctl accept_ra_min_rtr_lft to specify the
minimum acceptable router lifetime in an RA. If the received RA router
lifetime is less than the configured value (and not 0), the RA is
ignored.
This is useful for mobile devices, whose battery life can be impacted
by networks that configure RAs with a short lifetime. On such networks,
the device should never gain IPv6 provisioning and should attempt to
drop RAs via hardware offload, if available.

Signed-off-by: Patrick Rohr <prohr@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

uapi: net: ipv6: Replace fake flex-array with flex-array member

Zero-length arrays as fake flexible arrays are deprecated and we are
moving towards adopting C99 flexible-array members instead.

Address the following warning found with GCC-13 and
-fstrict-flex-arrays=3 enabled:
net/ipv6/exthdrs.c: In function ‘fl6_update_dst’:
net/ipv6/exthdrs.c:1393:28: warning: array subscript 0 is outside array bounds of ‘struct in6_addr[0]’ [-Warray-bounds=]
1393 | fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
| ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ./include/linux/ipv6.h:5,
from ./include/linux/icmpv6.h:6,
from net/ipv6/exthdrs.c:27:
./include/uapi/linux/ipv6.h:84:33: note: while referencing ‘addr’
84 | struct in6_addr addr[0];
| ^~~~
net/ipv6/exthdrs.c: In function ‘ipv6_push_rthdr0.isra’:
net/ipv6/exthdrs.c:1125:19: warning: array subscript <unknown> is outside array bounds of ‘struct in6_addr[0]’ [-Warray-bounds=]
1125 | phdr->addr[hops - 1] = **addr_p;
| ~~~~~~~~~~^~~~~~~~~~
./include/uapi/linux/ipv6.h:84:33: note: while referencing ‘addr’
84 | struct in6_addr addr[0];
| ^~~~

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].

Link: https://github.com/KSPP/linux/issues/21
Link: https://github.com/KSPP/linux/issues/276
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

uapi: add missing ip/ipv6 header dependencies for linux/stddef.h

Since commit 58e0be1ef6118 ("net: use struct_group to copy ip/ipv6
header addresses"), ip and ipv6 headers started to use the __struct_group
definition, which is defined at include/uapi/linux/stddef.h. However,
linux/stddef.h isn't explicitly included in include/uapi/linux/{ip,ipv6}.h,
which breaks build of xskxceiver bpf selftest if you install the uapi
headers in the system:

$ make V=1 xskxceiver -C tools/testing/selftests/bpf
...
make: Entering directory '(...)/tools/testing/selftests/bpf'
gcc -g -O0 -rdynamic -Wall -Werror (...)
In file included from xskxceiver.c:79:
/usr/include/linux/ip.h:103:9: error: expected specifier-qualifier-list before ‘__struct_group’
103 | __struct_group(/* no tag */, addrs, /* no attrs */,
| ^~~~~~~~~~~~~~
...

Include the missing <linux/stddef.h> dependency in ip.h and do the
same for the ipv6.h header.

Fixes: 58e0be1ef611 ("net: use struct_group to copy ip/ipv6 header addresses")
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: use struct_group to copy ip/ipv6 header addresses

kernel test robot reported warnings when build bonding module with
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/net/bonding/:

from ../drivers/net/bonding/bond_main.c:35:
In function ‘fortify_memcpy_chk’,
inlined from ‘iph_to_flow_copy_v4addrs’ at ../include/net/ip.h:566:2,
inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3984:3:
../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f
ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
413 | __read_overflow2_field(q_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘fortify_memcpy_chk’,
inlined from ‘iph_to_flow_copy_v6addrs’ at ../include/net/ipv6.h:900:2,
inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3994:3:
../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f
ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
413 | __read_overflow2_field(q_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is because we try to copy the whole ip/ip6 address to the flow_key,
while we only point the to ip/ip6 saddr. Note that since these are UAPI
headers, __struct_group() is used to avoid the compiler warnings.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: c3f8324188fa ("net: Add full IPv6 addresses to flow_keys")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20221115142400.1204786-1-liuhangbin@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/ipv6: Expand and rename accept_unsolicited_na to accept_untracked_na

RFC 9131 changes default behaviour of handling RX of NA messages when the
corresponding entry is absent in the neighbour cache. The current
implementation is limited to accept just unsolicited NAs. However, the
RFC is more generic where it also accepts solicited NAs. Both types
should result in adding a STALE entry for this case.

Expand accept_untracked_na behaviour to also accept solicited NAs to
be compliant with the RFC and rename the sysctl knob to
accept_untracked_na.

Fixes: f9a2fb73318e ("net/ipv6: Introduce accept_unsolicited_na knob to implement router-side changes for RFC9131")
Signed-off-by: Arun Ajith S <aajith@arista.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220530101414.65439-1-aajith@arista.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/ipv6: Introduce accept_unsolicited_na knob to implement router-side changes for RFC9131

Add a new neighbour cache entry in STALE state for routers on receiving
an unsolicited (gratuitous) neighbour advertisement with
target link-layer-address option specified.
This is similar to the arp_accept configuration for IPv4.
A new sysctl endpoint is created to turn on this behaviour:
/proc/sys/net/ipv6/conf/interface/accept_unsolicited_na.

Signed-off-by: Arun Ajith S <aajith@arista.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter

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 <prestwoj@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

ipv6: ioam: Data plane support for Pre-allocated Trace

Implement support for processing the IOAM Pre-allocated Trace with IPv6,
see [1] and [2]. Introduce a new IPv6 Hop-by-Hop TLV option, see IANA [3].

A new per-interface sysctl is introduced. The value is a boolean to accept (=1)
or ignore (=0, by default) IPv6 IOAM options on ingress for an interface:
- net.ipv6.conf.XXX.ioam6_enabled

Two other sysctls are introduced to define IOAM IDs, represented by an integer.
They are respectively per-namespace and per-interface:
- net.ipv6.ioam6_id
- net.ipv6.conf.XXX.ioam6_id

The value of the first one represents the IOAM ID of the node itself (u32; max
and default value = U32_MAX>>8, due to hop limit concatenation) while the other
represents the IOAM ID of an interface (u16; max and default value = U16_MAX).

Each "ioam6_id" sysctl has a "_wide" equivalent:
- net.ipv6.ioam6_id_wide
- net.ipv6.conf.XXX.ioam6_id_wide

The value of the first one represents the wide IOAM ID of the node itself (u64;
max and default value = U64_MAX>>8, due to hop limit concatenation) while the
other represents the wide IOAM ID of an interface (u32; max and default value
= U32_MAX).

The use of short and wide equivalents is not exclusive, a deployment could
choose to leverage both. For example, net.ipv6.conf.XXX.ioam6_id (short format)
could be an identifier for a physical interface, whereas
net.ipv6.conf.XXX.ioam6_id_wide (wide format) could be an identifier for a
logical sub-interface. Documentation about new sysctls is provided at the end
of this patchset.

Two relativistic hash tables are used: one for IOAM namespaces, the other for
IOAM schemas. A namespace can only have a single active schema and a schema
can only be attached to a single namespace (1:1 relationship).

[1] https://tools.ietf.org/html/draft-ietf-ippm-ioam-ipv6-options
[2] https://tools.ietf.org/html/draft-ietf-ippm-ioam-data
[3] https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-2

Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

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 <pchaudhary@linkedin.com>
Signed-off-by: Zhenggen Xu <zxu@linkedin.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20210125214430.24079-1-pchaudhary@linkedin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: ipv6: add support for rpl sr exthdr

This patch adds rpl source routing receive handling. Everything works
only if sysconf "rpl_seg_enabled" and source routing is enabled. Mostly
the same behaviour as IPv6 segmentation routing. To handle compression
and uncompression a rpl.c file is created which contains the necessary
functionality. The receive handling will also care about IPv6
encapsulated so far it's specified as possible nexthdr in RFC 6554.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ipv6: sysctl to specify IPv6 ND traffic class

Add a per-device sysctl to specify the default traffic class to use for
kernel originated IPv6 Neighbour Discovery packets.

Currently this includes:

- Router Solicitation (ICMPv6 type 133)
ndisc_send_rs() -> ndisc_send_skb() -> ip6_nd_hdr()

- Neighbour Solicitation (ICMPv6 type 135)
ndisc_send_ns() -> ndisc_send_skb() -> ip6_nd_hdr()

- Neighbour Advertisement (ICMPv6 type 136)
ndisc_send_na() -> ndisc_send_skb() -> ip6_nd_hdr()

- Redirect (ICMPv6 type 137)
ndisc_send_redirect() -> ndisc_send_skb() -> ip6_nd_hdr()

and if the kernel ever gets around to generating RA's,
it would presumably also include:

- Router Advertisement (ICMPv6 type 134)
(radvd daemon could pick up on the kernel setting and use it)

Interface drivers may examine the Traffic Class value and translate
the DiffServ Code Point into a link-layer appropriate traffic
prioritization scheme. An example of mapping IETF DSCP values to
IEEE 802.11 User Priority values can be found here:

https://tools.ietf.org/html/draft-ietf-tsvwg-ieee-802-11

The expected primary use case is to properly prioritize ND over wifi.

Testing:
jzem22:~# cat /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
0
jzem22:~# echo -1 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
-bash: echo: write error: Invalid argument
jzem22:~# echo 256 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
-bash: echo: write error: Invalid argument
jzem22:~# echo 0 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
jzem22:~# echo 255 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
jzem22:~# cat /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
255
jzem22:~# echo 34 > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
jzem22:~# cat /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
34

jzem22:~# echo $[0xDC] > /proc/sys/net/ipv6/conf/eth0/ndisc_tclass
jzem22:~# tcpdump -v -i eth0 icmp6 and src host jzem22.pgc and dst host fe80::1
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
IP6 (class 0xdc, hlim 255, next-header ICMPv6 (58) payload length: 24)
jzem22.pgc > fe80::1: [icmp6 sum ok] ICMP6, neighbor advertisement,
length 24, tgt is jzem22.pgc, Flags [solicited]

(based on original change written by Erik Kline, with minor changes)

v2: fix 'suspicious rcu_dereference_check() usage'
by explicitly grabbing the rcu_read_lock.

Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Erik Kline <ek@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

License cleanup: add SPDX license identifier to uapi header files with no license

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net: ipv6: Add sysctl for minimum prefix len acceptable in RIOs.

This commit adds a new sysctl accept_ra_rt_info_min_plen that
defines the minimum acceptable prefix length of Route Information
Options. The new sysctl is intended to be used together with
accept_ra_rt_info_max_plen to configure a range of acceptable
prefix lengths. It is useful to prevent misconfigurations from
unintentionally blackholing too much of the IPv6 address space
(e.g., home routers announcing RIOs for fc00::/7, which is
incorrect).

Signed-off-by: Joel Scherpelz <jscherpelz@google.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: Provide ipv6 version of "disable_policy" sysctl

This provides equivalent functionality to the existing ipv4
"disable_policy" systcl. ie. Allows IPsec processing to be skipped
on terminating packets on a per-interface basis.

Signed-off-by: David Forster <dforster@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6: allow sysctl to change link-local address generation mode

The address generation mode for IPv6 link-local can only be configured
by netlink messages. This patch adds the ability to change the address
generation mode via sysctl.

v1 -> v2
Removed the rtnl lock and switch to use RCU lock to iterate through
the netdev list.

v2 -> v3
Removed the addrgenmode variable from the idev structure and use the
systcl storage for the flag.

Simplifed the logic for sysctl handling by removing the supported
for all operation.

Added support for more types of tunnel interfaces for link-local
address generation.

Based the patches from net-next.

v3 -> v4
Removed unnecessary whitespace changes.

Signed-off-by: Felix Jia <felix.jia@alliedtelesis.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6 addrconf: Implemented enhanced DAD (RFC7527)

Implemented RFC7527 Enhanced DAD.
IPv6 duplicate address detection can fail if there is some temporary
loopback of Ethernet frames. RFC7527 solves this by including a random
nonce in the NS messages used for DAD, and if an NS is received with the
same nonce it is assumed to be a looped back DAD probe and is ignored.
RFC7527 is enabled by default. Can be disabled by setting both of
conf/{all,interface}/enhanced_dad to zero.

Signed-off-by: Erik Nordmark <nordmark@arista.com>
Signed-off-by: Bob Gilligan <gilligan@arista.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sr: add core files for SR HMAC support

This patch adds the necessary functions to compute and check the HMAC signature
of an SR-enabled packet. Two HMAC algorithms are supported: hmac(sha1) and
hmac(sha256).

In order to avoid dynamic memory allocation for each HMAC computation,
a per-cpu ring buffer is allocated for this purpose.

A new per-interface sysctl called seg6_require_hmac is added, allowing a
user-defined policy for processing HMAC-signed SR-enabled packets.
A value of -1 means that the HMAC field will always be ignored.
A value of 0 means that if an HMAC field is present, its validity will
be enforced (the packet is dropped is the signature is incorrect).
Finally, a value of 1 means that any SR-enabled packet that does not
contain an HMAC signature or whose signature is incorrect will be dropped.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: implement dataplane support for rthdr type 4 (Segment Routing Header)

Implement minimal support for processing of SR-enabled packets
as described in
https://tools.ietf.org/html/draft-ietf-6man-segment-routing-header-02.

This patch implements the following operations:
- Intermediate segment endpoint: incrementation of active segment and rerouting.
- Egress for SR-encapsulated packets: decapsulation of outer IPv6 header + SRH
and routing of inner packet.
- Cleanup flag support for SR-inlined packets: removal of SRH if we are the
penultimate segment endpoint.

A per-interface sysctl seg6_enabled is provided, to accept/deny SR-enabled
packets. Default is deny.

This patch does not provide support for HMAC-signed packets.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6 addrconf: implement RFC7559 router solicitation backoff

This implements:
https://tools.ietf.org/html/rfc7559

Backoff is performed according to RFC3315 section 14:
https://tools.ietf.org/html/rfc3315#section-14

We allow setting /proc/sys/net/ipv6/conf/*/router_solicitations
to a negative value meaning an unlimited number of retransmits,
and we make this the new default (inline with the RFC).

We also add a new setting:
/proc/sys/net/ipv6/conf/*/router_solicitation_max_interval
defaulting to 1 hour (per RFC recommendation).

Signed-off-by: Maciej Żenczykowski <maze@google.com>
Acked-by: Erik Kline <ek@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Revert "ipv6: Revert optional address flusing on ifdown."

This reverts commit 841645b5f2dfceac69b78fcd0c9050868d41ea61.

Ok, this puts the feature back. I've decided to apply David A.'s
bug fix and run with that rather than make everyone wait another
whole release for this feature.

Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: Revert optional address flusing on ifdown.

This reverts the following three commits:

70af921db6f8835f4b11c65731116560adb00c14
799977d9aafbf0ca0b9c39b04cbfb16db71302c9
f1705ec197e705b79ea40fe7a2cc5acfa1d3bfac

The feature was ill conceived, has terrible semantics, and has added
nothing but regressions to the already fragile ipv6 stack.

Fixes: f1705ec197e7 ("net: ipv6: Make address flushing on ifdown optional")
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ipv6: Make address flushing on ifdown optional

Currently, all ipv6 addresses are flushed when the interface is configured
down, including global, static addresses:

$ ip -6 addr show dev eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 2100:1::2/120 scope global
valid_lft forever preferred_lft forever
inet6 fe80::e0:f9ff:fe79:34bd/64 scope link
valid_lft forever preferred_lft forever
$ ip link set dev eth1 down
$ ip -6 addr show dev eth1
<< nothing; all addresses have been flushed>>

Add a new sysctl to make this behavior optional. The new setting defaults to
flush all addresses to maintain backwards compatibility. When the set global
addresses with no expire times are not flushed on an admin down. The sysctl
is per-interface or system-wide for all interfaces

$ sysctl -w net.ipv6.conf.eth1.keep_addr_on_down=1
or
$ sysctl -w net.ipv6.conf.all.keep_addr_on_down=1

Will keep addresses on eth1 on an admin down.

$ ip -6 addr show dev eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 2100:1::2/120 scope global
valid_lft forever preferred_lft forever
inet6 fe80::e0:f9ff:fe79:34bd/64 scope link
valid_lft forever preferred_lft forever
$ ip link set dev eth1 down
$ ip -6 addr show dev eth1
3: eth1: <BROADCAST,MULTICAST> mtu 1500 state DOWN qlen 1000
inet6 2100:1::2/120 scope global tentative
valid_lft forever preferred_lft forever
inet6 fe80::e0:f9ff:fe79:34bd/64 scope link tentative
valid_lft forever preferred_lft forever

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: add option to drop unsolicited neighbor advertisements

In certain 802.11 wireless deployments, there will be NA proxies
that use knowledge of the network to correctly answer requests.
To prevent unsolicitd advertisements on the shared medium from
being a problem, on such deployments wireless needs to drop them.

Enable this by providing an option called "drop_unsolicited_na".

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: add option to drop unicast encapsulated in L2 multicast

In order to solve a problem with 802.11, the so-called hole-196 attack,
add an option (sysctl) called "drop_unicast_in_l2_multicast" which, if
enabled, causes the stack to drop IPv6 unicast packets encapsulated in
link-layer multi- or broadcast frames. Such frames can (as an attack)
be created by any member of the same wireless network and transmitted
as valid encrypted frames since the symmetric key for broadcast frames
is shared between all stations.

Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ipv6 sysctl option to ignore routes when nexthop link is down

Like the ipv4 patch with a similar title, this adds a sysctl to allow
the user to change routing behavior based on whether or not the
interface associated with the nexthop was an up or down link. The
default setting preserves the current behavior, but anyone that enables
it will notice that nexthops on down interfaces will no longer be
selected:

net.ipv6.conf.all.ignore_routes_with_linkdown = 0
net.ipv6.conf.default.ignore_routes_with_linkdown = 0
net.ipv6.conf.lo.ignore_routes_with_linkdown = 0
...

When the above sysctls are set, not only will link status be reported to
userspace, but an indication that a nexthop is dead and will not be used
is also reported.

1000::/8 via 7000::2 dev p7p1 metric 1024 dead linkdown pref medium
1000::/8 via 8000::2 dev p8p1 metric 1024 pref medium
7000::/8 dev p7p1 proto kernel metric 256 dead linkdown pref medium
8000::/8 dev p8p1 proto kernel metric 256 pref medium
9000::/8 via 8000::2 dev p8p1 metric 2048 pref medium
9000::/8 via 7000::2 dev p7p1 metric 1024 dead linkdown pref medium
fe80::/64 dev p7p1 proto kernel metric 256 dead linkdown pref medium
fe80::/64 dev p8p1 proto kernel metric 256 pref medium

This also adds devconf support and notification when sysctl values
change.

v2: drop use of rt6i_nhflags since it is not needed right now

Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6: add sysctl option accept_ra_min_hop_limit

Commit 6fd99094de2b ("ipv6: Don't reduce hop limit for an interface")
disabled accept hop limit from RA if it is smaller than the current hop
limit for security stuff. But this behavior kind of break the RFC definition.

RFC 4861, 6.3.4. Processing Received Router Advertisements
A Router Advertisement field (e.g., Cur Hop Limit, Reachable Time,
and Retrans Timer) may contain a value denoting that it is
unspecified. In such cases, the parameter should be ignored and the
host should continue using whatever value it is already using.

If the received Cur Hop Limit value is non-zero, the host SHOULD set
its CurHopLimit variable to the received value.

So add sysctl option accept_ra_min_hop_limit to let user choose the minimum
hop limit value they can accept from RA. And set default to 1 to meet RFC
standards.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sysctl to restrict candidate source addresses

Per RFC 6724, section 4, "Candidate Source Addresses":

It is RECOMMENDED that the candidate source addresses be the set
of unicast addresses assigned to the interface that will be used
to send to the destination (the "outgoing" interface).

Add a sysctl to enable this behaviour.

Signed-off-by: Erik Kline <ek@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: introduce secret_stable to ipv6_devconf

This patch implements the procfs logic for the stable_address knob:
The secret is formatted as an ipv6 address and will be stored per
interface and per namespace. We track initialized flag and return EIO
errors until the secret is set.

We don't inherit the secret to newly created namespaces.

Cc: Erik Kline <ek@google.com>
Cc: Fernando Gont <fgont@si6networks.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: YOSHIFUJI Hideaki/吉藤英明 <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ipv6: Add sysctl entry to disable MTU updates from RA

The kernel forcefully applies MTU values received in router
advertisements provided the new MTU is less than the current. This
behavior is undesirable when the user space is managing the MTU. Instead
a sysctl flag 'accept_ra_mtu' is introduced such that the user space
can control whether or not RA provided MTU updates should be applied. The
default behavior is unchanged; user space must explicitly set this flag
to 0 for RA MTUs to be ignored.

Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: directly include libc-compat.h in ipv6.h

Patch 3b50d9029809 ("ipv6: fix redefinition of in6_pktinfo ...")
fixed a libc compatibility issue in ipv6 structure definitions
as described in include/uapi/linux/libc-compat.h.

It relies on including linux/in6.h to include libc-compat.h itself.
Include that file directly to clearly communicate the dependency
(libc-compat.h: "This include must be as early as possible").

Signed-off-by: Willem de Bruijn <willemb@google.com>

----

As discussed in http://patchwork.ozlabs.org/patch/427384/
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: fix redefinition of in6_pktinfo and ip6_mtuinfo

Both netinet/in.h and linux/ipv6.h define these two structs,
if we include both of them, we got:

/usr/include/linux/ipv6.h:19:8: error: redefinition of ‘struct in6_pktinfo’
struct in6_pktinfo {
^
In file included from /usr/include/arpa/inet.h:22:0,
from txtimestamp.c:33:
/usr/include/netinet/in.h:524:8: note: originally defined here
struct in6_pktinfo
^
In file included from txtimestamp.c:40:0:
/usr/include/linux/ipv6.h:24:8: error: redefinition of ‘struct ip6_mtuinfo’
struct ip6_mtuinfo {
^
In file included from /usr/include/arpa/inet.h:22:0,
from txtimestamp.c:33:
/usr/include/netinet/in.h:531:8: note: originally defined here
struct ip6_mtuinfo
^
So similarly to what we did for in6_addr, we need to sync with
libc header on their definitions.

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ipv6: Add a sysctl to make optimistic addresses useful candidates

Add a sysctl that causes an interface's optimistic addresses
to be considered equivalent to other non-deprecated addresses
for source address selection purposes. Preferred addresses
will still take precedence over optimistic addresses, subject
to other ranking in the source address selection algorithm.

This is useful where different interfaces are connected to
different networks from different ISPs (e.g., a cell network
and a home wifi network).

The current behaviour complies with RFC 3484/6724, and it
makes sense if the host has only one interface, or has
multiple interfaces on the same network (same or cooperating
administrative domain(s), but not in the multiple distinct
networks case.

For example, if a mobile device has an IPv6 address on an LTE
network and then connects to IPv6-enabled wifi, while the wifi
IPv6 address is undergoing DAD, IPv6 connections will try use
the wifi default route with the LTE IPv6 address, and will get
stuck until they time out.

Also, because optimistic nodes can receive frames, issue
an RTM_NEWADDR as soon as DAD starts (with the IFA_F_OPTIMSTIC
flag appropriately set). A second RTM_NEWADDR is sent if DAD
completes (the address flags have changed), otherwise an
RTM_DELADDR is sent.

Also: add an entry in ip-sysctl.txt for optimistic_dad.

Signed-off-by: Erik Kline <ek@google.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: Allow accepting RA from local IP addresses.

This can be used in virtual networking applications, and
may have other uses as well. The option is disabled by
default.

A specific use case is setting up virtual routers, bridges, and
hosts on a single OS without the use of network namespaces or
virtual machines. With proper use of ip rules, routing tables,
veth interface pairs and/or other virtual interfaces,
and applications that can bind to interfaces and/or IP addresses,
it is possibly to create one or more virtual routers with multiple
hosts attached. The host interfaces can act as IPv6 systems,
with radvd running on the ports in the virtual routers. With the
option provided in this patch enabled, those hosts can now properly
obtain IPv6 addresses from the radvd.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: drop fragmented ndisc packets by default (RFC 6980)

This patch implements RFC6980: Drop fragmented ndisc packets by
default. If a fragmented ndisc packet is received the user is informed
that it is possible to disable the check.

Cc: Fernando Gont <fernando@gont.com.ar>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: make unsolicited report intervals configurable for mld

Commit cab70040dfd95ee32144f02fade64f0cb94f31a0 ("net: igmp:
Reduce Unsolicited report interval to 1s when using IGMPv3") and
2690048c01f32bf45d1c1e1ab3079bc10ad2aea7 ("net: igmp: Allow user-space
configuration of igmp unsolicited report interval") by William Manley made
igmp unsolicited report intervals configurable per interface and corrected
the interval of unsolicited igmpv3 report messages resendings to 1s.

Same needs to be done for IPv6:

MLDv1 (RFC2710 7.10.): 10 seconds
MLDv2 (RFC3810 9.11.): 1 second

Both intervals are configurable via new procfs knobs
mldv1_unsolicited_report_interval and mldv2_unsolicited_report_interval.

(also added .force_mld_version to ipv6_devconf_dflt to bring structs in
line without semantic changes)

v2:
a) Joined documentation update for IPv4 and IPv6 MLD/IGMP
unsolicited_report_interval procfs knobs.
b) incorporate stylistic feedback from William Manley

v3:
a) add new DEVCONF_* values to the end of the enum (thanks to David
Miller)

Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: William Manley <william.manley@youview.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: Store Router Alert option in IP6CB directly.

Router Alert option is very small and we can store the value
itself in the skb.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: add knob to send unsolicited ND on link-layer address change

This patch introduces a new knob ndisc_notify. If enabled, the kernel
will transmit an unsolicited neighbour advertisement on link-layer address
change to update the neighbour tables of the corresponding hosts more quickly.

This is the equivalent to arp_notify in ipv4 world.

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

UAPI: (Scripted) Disintegrate include/linux

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>