seg6: add NEXT-C-SID support for SRv6 End.X behavior

The NEXT-C-SID mechanism described in [1] offers the possibility of
encoding several SRv6 segments within a single 128 bit SID address. Such
a SID address is called a Compressed SID (C-SID) container. In this way,
the length of the SID List can be drastically reduced.

A SID instantiated with the NEXT-C-SID flavor considers an IPv6 address
logically structured in three main blocks: i) Locator-Block; ii)
Locator-Node Function; iii) Argument.

C-SID container
+------------------------------------------------------------------+
| Locator-Block |Loc-Node| Argument |
| |Function| |
+------------------------------------------------------------------+
<--------- B -----------> <- NF -> <------------- A --------------->

(i) The Locator-Block can be any IPv6 prefix available to the provider;

(ii) The Locator-Node Function represents the node and the function to
be triggered when a packet is received on the node;

(iii) The Argument carries the remaining C-SIDs in the current C-SID
container.

This patch leverages the NEXT-C-SID mechanism previously introduced in the
Linux SRv6 subsystem [2] to support SID compression capabilities in the
SRv6 End.X behavior [3].
An SRv6 End.X behavior with NEXT-C-SID flavor works as an End.X behavior
but it is capable of processing the compressed SID List encoded in C-SID
containers.

An SRv6 End.X behavior with NEXT-C-SID flavor can be configured to support
user-provided Locator-Block and Locator-Node Function lengths. In this
implementation, such lengths must be evenly divisible by 8 (i.e. must be
byte-aligned), otherwise the kernel informs the user about invalid
values with a meaningful error code and message through netlink_ext_ack.

If Locator-Block and/or Locator-Node Function lengths are not provided
by the user during configuration of an SRv6 End.X behavior instance with
NEXT-C-SID flavor, the kernel will choose their default values i.e.,
32-bit Locator-Block and 16-bit Locator-Node Function.

[1] - https://datatracker.ietf.org/doc/html/draft-ietf-spring-srv6-srh-compression
[2] - https://lore.kernel.org/all/20220912171619.16943-1-andrea.mayer@uniroma2.it/
[3] - https://datatracker.ietf.org/doc/html/rfc8986#name-endx-l3-cross-connect

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230812180926.16689-2-andrea.mayer@uniroma2.it
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: add PSP flavor support for SRv6 End behavior

The "flavors" framework defined in RFC8986 [1] represents additional
operations that can modify or extend a subset of existing behaviors such as
SRv6 End, End.X and End.T. We report these flavors hereafter:
- Penultimate Segment Pop (PSP);
- Ultimate Segment Pop (USP);
- Ultimate Segment Decapsulation (USD).

Depending on how the Segment Routing Header (SRH) has to be handled, an
SRv6 End* behavior can support these flavors either individually or in
combinations.
In this patch, we only consider the PSP flavor for the SRv6 End behavior.

A PSP enabled SRv6 End behavior is used by the Source/Ingress SR node
(i.e., the one applying the SRv6 Policy) when it needs to instruct the
penultimate SR Endpoint node listed in the SID List (carried by the SRH) to
remove the SRH from the IPv6 header.

Specifically, a PSP enabled SRv6 End behavior processes the SRH by:
i) decreasing the Segment Left (SL) from 1 to 0;
ii) copying the Last Segment IDentifier (SID) into the IPv6 Destination
Address (DA);
iii) removing (i.e., popping) the outer SRH from the extension headers
following the IPv6 header.

It is important to note that PSP operation (steps i, ii, iii) takes place
only at a penultimate SR Segment Endpoint node (i.e., when the SL=1) and
does not happen at non-penultimate Endpoint nodes. Indeed, when a SID of
PSP flavor is processed at a non-penultimate SR Segment Endpoint node, the
PSP operation is not performed because it would not be possible to decrease
the SL from 1 to 0.

SL=2 SL=1 SL=0
| | |
For example, given the SRv6 policy (SID List := < X, Y, Z >):
- a PSP enabled SRv6 End behavior bound to SID "Y" will apply the PSP
operation as Segment Left (SL) is 1, corresponding to the Penultimate
Segment of the SID List;
- a PSP enabled SRv6 End behavior bound to SID "X" will *NOT* apply the
PSP operation as the Segment Left is 2. This behavior instance will
apply the "standard" End packet processing, ignoring the configured PSP
flavor at all.

[1] - RFC8986: https://datatracker.ietf.org/doc/html/rfc8986

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

seg6: factor out End lookup nexthop processing to a dedicated function

The End nexthop lookup/input operations are moved into a new helper
function named input_action_end_finish(). This avoids duplicating the
code needed to compute the nexthop in the different flavors of the End
behavior.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: Remove the obsolte u64_stats_fetch_*_irq() users (net).

Now that the 32bit UP oddity is gone and 32bit uses always a sequence
count, there is no need for the fetch_irq() variants anymore.

Convert to the regular interface.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: add NEXT-C-SID support for SRv6 End behavior

The NEXT-C-SID mechanism described in [1] offers the possibility of
encoding several SRv6 segments within a single 128 bit SID address. Such
a SID address is called a Compressed SID (C-SID) container. In this way,
the length of the SID List can be drastically reduced.

A SID instantiated with the NEXT-C-SID flavor considers an IPv6 address
logically structured in three main blocks: i) Locator-Block; ii)
Locator-Node Function; iii) Argument.

C-SID container
+------------------------------------------------------------------+
| Locator-Block |Loc-Node| Argument |
| |Function| |
+------------------------------------------------------------------+
<--------- B -----------> <- NF -> <------------- A --------------->

(i) The Locator-Block can be any IPv6 prefix available to the provider;

(ii) The Locator-Node Function represents the node and the function to
be triggered when a packet is received on the node;

(iii) The Argument carries the remaining C-SIDs in the current C-SID
container.

The NEXT-C-SID mechanism relies on the "flavors" framework defined in
[2]. The flavors represent additional operations that can modify or
extend a subset of the existing behaviors.

This patch introduces the support for flavors in SRv6 End behavior
implementing the NEXT-C-SID one. An SRv6 End behavior with NEXT-C-SID
flavor works as an End behavior but it is capable of processing the
compressed SID List encoded in C-SID containers.

An SRv6 End behavior with NEXT-C-SID flavor can be configured to support
user-provided Locator-Block and Locator-Node Function lengths. In this
implementation, such lengths must be evenly divisible by 8 (i.e. must be
byte-aligned), otherwise the kernel informs the user about invalid
values with a meaningful error code and message through netlink_ext_ack.

If Locator-Block and/or Locator-Node Function lengths are not provided
by the user during configuration of an SRv6 End behavior instance with
NEXT-C-SID flavor, the kernel will choose their default values i.e.,
32-bit Locator-Block and 16-bit Locator-Node Function.

[1] - https://datatracker.ietf.org/doc/html/draft-ietf-spring-srv6-srh-compression
[2] - https://datatracker.ietf.org/doc/html/rfc8986

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

seg6: add netlink_ext_ack support in parsing SRv6 behavior attributes

An SRv6 behavior instance can be set up using mandatory and/or optional
attributes.
In the setup phase, each supplied attribute is parsed and processed. If
the parsing operation fails, the creation of the behavior instance stops
and an error number/code is reported to the user. In many cases, it is
challenging for the user to figure out exactly what happened by relying
only on the error code.

For this reason, we add the support for netlink_ext_ack in parsing SRv6
behavior attributes. In this way, when an SRv6 behavior attribute is
parsed and an error occurs, the kernel can send a message to the
userspace describing the error through a meaningful text message in
addition to the classic error code.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: seg6: initialize induction variable to first valid array index

Fixes the following warnings observed when building
CONFIG_IPV6_SEG6_LWTUNNEL=y with clang:

net/ipv6/seg6_local.o: warning: objtool: seg6_local_fill_encap() falls
through to next function seg6_local_get_encap_size()
net/ipv6/seg6_local.o: warning: objtool: seg6_local_cmp_encap() falls
through to next function input_action_end()

LLVM can fully unroll loops in seg6_local_get_encap_size() and
seg6_local_cmp_encap(). One issue in those loops is that the induction
variable is initialized to 0. The loop iterates over members of
seg6_action_params, a global array of struct seg6_action_param calling
their put() function pointer members. seg6_action_param uses an array
initializer to initialize SEG6_LOCAL_SRH and later elements, which is
the third enumeration of an anonymous union.

The guard `if (attrs & SEG6_F_ATTR(i))` may prevent this from being
called at runtime, but it would still be UB for
`seg6_action_params[0]->put` to be called; the unrolled loop will make
the initial iterations unreachable, which LLVM will later rotate to
fallthrough to the next function.

Make this more obvious that this cannot happen to the compiler by
initializing the loop induction variable to the minimum valid index that
seg6_action_params is initialized to.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220802161203.622293-1-ndesaulniers@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: fix skb checksum in SRv6 End.B6 and End.B6.Encaps behaviors

The SRv6 End.B6 and End.B6.Encaps behaviors rely on functions
seg6_do_srh_{encap,inline}() to, respectively: i) encapsulate the
packet within an outer IPv6 header with the specified Segment Routing
Header (SRH); ii) insert the specified SRH directly after the IPv6
header of the packet.

This patch removes the initialization of the IPv6 header payload length
from the input_action_end_b6{_encap}() functions, as it is now handled
properly by seg6_do_srh_{encap,inline}() to avoid corruption of the skb
checksum.

Fixes: 140f04c33bbc ("ipv6: sr: implement several seg6local actions")
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: seg6: fix seg6_lookup_any_nexthop() to handle VRFs using flowi_l3mdev

Commit 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif
reset for port devices") adds a new entry (flowi_l3mdev) in the common
flow struct used for indicating the l3mdev index for later rule and
table matching.
The l3mdev_update_flow() has been adapted to properly set the
flowi_l3mdev based on the flowi_oif/flowi_iif. In fact, when a valid
flowi_iif is supplied to the l3mdev_update_flow(), this function can
update the flowi_l3mdev entry only if it has not yet been set (i.e., the
flowi_l3mdev entry is equal to 0).

The SRv6 End.DT6 behavior in VRF mode leverages a VRF device in order to
force the routing lookup into the associated routing table. This routing
operation is performed by seg6_lookup_any_nextop() preparing a flowi6
data structure used by ip6_route_input_lookup() which, in turn,
(indirectly) invokes l3mdev_update_flow().

However, seg6_lookup_any_nexthop() does not initialize the new
flowi_l3mdev entry which is filled with random garbage data. This
prevents l3mdev_update_flow() from properly updating the flowi_l3mdev
with the VRF index, and thus SRv6 End.DT6 (VRF mode)/DT46 behaviors are
broken.

This patch correctly initializes the flowi6 instance allocated and used
by seg6_lookup_any_nexhtop(). Specifically, the entire flowi6 instance
is wiped out: in case new entries are added to flowi/flowi6 (as happened
with the flowi_l3mdev entry), we should no longer have incorrectly
initialized values. As a result of this operation, the value of
flowi_l3mdev is also set to 0.

The proposed fix can be tested easily. Starting from the commit
referenced in the Fixes, selftests [1],[2] indicate that the SRv6
End.DT6 (VRF mode)/DT46 behaviors no longer work correctly. By applying
this patch, those behaviors are back to work properly again.

[1] - tools/testing/selftests/net/srv6_end_dt46_l3vpn_test.sh
[2] - tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh

Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices")
Reported-by: Anton Makarov <am@3a-alliance.com>
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220608091917.20345-1-andrea.mayer@uniroma2.it
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: Don't include filter.h from net/sock.h

sock.h is pretty heavily used (5k objects rebuilt on x86 after
it's touched). We can drop the include of filter.h from it and
add a forward declaration of struct sk_filter instead.
This decreases the number of rebuilt objects when bpf.h
is touched from ~5k to ~1k.

There's a lot of missing includes this was masking. Primarily
in networking tho, this time.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org

seg6: export get_srh() for ICMP handling

An ICMP error message can contain in its message body part of an IPv6
packet which invoked the error. Such a packet might contain a segment
router header. Export get_srh() so the ICMP code can make use of it.

Since his changes the scope of the function from local to global, add
the seg6_ prefix to keep the namespace clean. And move it into seg6.c
so it is always available, not just when IPV6_SEG6_LWTUNNEL is
enabled.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: seg6: remove duplicated include

Remove all but the first include of net/lwtunnel.h from 'seg6_local.c.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Lv Ruyi <lv.ruyi@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

netfilter: add netfilter hooks to SRv6 data plane

This patch introduces netfilter hooks for solving the problem that
conntrack couldn't record both inner flows and outer flows.

This patch also introduces a new sysctl toggle for enabling lightweight
tunnel netfilter hooks.

Signed-off-by: Ryoga Saito <contact@proelbtn.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

seg6: add support for SRv6 End.DT46 Behavior

IETF RFC 8986 [1] includes the definition of SRv6 End.DT4, End.DT6, and
End.DT46 Behaviors.

The current SRv6 code in the Linux kernel only implements End.DT4 and
End.DT6 which can be used respectively to support IPv4-in-IPv6 and
IPv6-in-IPv6 VPNs. With End.DT4 and End.DT6 it is not possible to create a
single SRv6 VPN tunnel to carry both IPv4 and IPv6 traffic.

The proposed End.DT46 implementation is meant to support the decapsulation
of IPv4 and IPv6 traffic coming from a single SRv6 tunnel.
The implementation of the SRv6 End.DT46 Behavior in the Linux kernel
greatly simplifies the setup and operations of SRv6 VPNs.

The SRv6 End.DT46 Behavior leverages the infrastructure of SRv6 End.DT{4,6}
Behaviors implemented so far, because it makes use of a VRF device in
order to force the routing lookup into the associated routing table.

To make the End.DT46 work properly, it must be guaranteed that the routing
table used for routing lookup operations is bound to one and only one VRF
during the tunnel creation. Such constraint has to be enforced by enabling
the VRF strict_mode sysctl parameter, i.e.:

$ sysctl -wq net.vrf.strict_mode=1

Note that the same approach is used for the SRv6 End.DT4 Behavior and for
the End.DT6 Behavior in VRF mode.

The command used to instantiate an SRv6 End.DT46 Behavior is
straightforward, i.e.:

$ ip -6 route add 2001:db8::1 encap seg6local action End.DT46 vrftable 100 dev vrf100.

[1] https://www.rfc-editor.org/rfc/rfc8986.html#name-enddt46-decapsulation-and-s

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Performance and impact of SRv6 End.DT46 Behavior on the SRv6 Networking
=======================================================================

This patch aims to add the SRv6 End.DT46 Behavior with minimal impact on
the performance of SRv6 End.DT4 and End.DT6 Behaviors.
In order to verify this, we tested the performance of the newly introduced
SRv6 End.DT46 Behavior and compared it with the performance of SRv6
End.DT{4,6} Behaviors, considering both the patched kernel and the kernel
before applying the End.DT46 patch (referred to as vanilla kernel).

In details, the following decapsulation scenarios were considered:

1.a) IPv6 traffic in SRv6 End.DT46 Behavior on patched kernel;
1.b) IPv4 traffic in SRv6 End.DT46 Behavior on patched kernel;
2.a) SRv6 End.DT6 Behavior (VRF mode) on patched kernel;
2.b) SRv6 End.DT4 Behavior on patched kernel;
3.a) SRv6 End.DT6 Behavior (VRF mode) on vanilla kernel (without the
End.DT46 patch);
3.b) SRv6 End.DT4 Behavior on vanilla kernel (without the End.DT46 patch).

All tests were performed on a testbed deployed on the CloudLab [2]
facilities. We considered IPv{4,6} traffic handled by a single core (at 2.4
GHz on a Xeon(R) CPU E5-2630 v3) on kernel 5.13-rc1 using packets of size
~ 100 bytes.

Scenario (1.a): average 684.70 kpps; std. dev. 0.7 kpps;
Scenario (1.b): average 711.69 kpps; std. dev. 1.2 kpps;
Scenario (2.a): average 690.70 kpps; std. dev. 1.2 kpps;
Scenario (2.b): average 722.22 kpps; std. dev. 1.7 kpps;
Scenario (3.a): average 690.02 kpps; std. dev. 2.6 kpps;
Scenario (3.b): average 721.91 kpps; std. dev. 1.2 kpps;

Considering the results for the patched kernel (1.a, 1.b, 2.a, 2.b) we
observe that the performance degradation incurred in using End.DT46 rather
than End.DT6 and End.DT4 respectively for IPv6 and IPv4 traffic is minimal,
around 0.9% and 1.5%. Such very minimal performance degradation is the
price to be paid if one prefers to use a single tunnel capable of handling
both types of traffic (IPv4 and IPv6).

Comparing the results for End.DT4 and End.DT6 under the patched and the
vanilla kernel (2.a, 2.b, 3.a, 3.b) we observe that the introduction of the
End.DT46 patch has no impact on the performance of End.DT4 and End.DT6.

[2] https://www.cloudlab.us

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: add counters support for SRv6 Behaviors

This patch provides counters for SRv6 Behaviors as defined in [1],
section 6. For each SRv6 Behavior instance, counters defined in [1] are:

- the total number of packets that have been correctly processed;
- the total amount of traffic in bytes of all packets that have been
correctly processed;

In addition, this patch introduces a new counter that counts the number of
packets that have NOT been properly processed (i.e. errors) by an SRv6
Behavior instance.

Counters are not only interesting for network monitoring purposes (i.e.
counting the number of packets processed by a given behavior) but they also
provide a simple tool for checking whether a behavior instance is working
as we expect or not.
Counters can be useful for troubleshooting misconfigured SRv6 networks.
Indeed, an SRv6 Behavior can silently drop packets for very different
reasons (i.e. wrong SID configuration, interfaces set with SID addresses,
etc) without any notification/message to the user.

Due to the nature of SRv6 networks, diagnostic tools such as ping and
traceroute may be ineffective: paths used for reaching a given router can
be totally different from the ones followed by probe packets. In addition,
paths are often asymmetrical and this makes it even more difficult to keep
up with the journey of the packets and to understand which behaviors are
actually processing our traffic.

When counters are enabled on an SRv6 Behavior instance, it is possible to
verify if packets are actually processed by such behavior and what is the
outcome of the processing. Therefore, the counters for SRv6 Behaviors offer
an non-invasive observability point which can be leveraged for both traffic
monitoring and troubleshooting purposes.

[1] https://www.rfc-editor.org/rfc/rfc8986.html#name-counters

Troubleshooting using SRv6 Behavior counters
--------------------------------------------

Let's make a brief example to see how helpful counters can be for SRv6
networks. Let's consider a node where an SRv6 End Behavior receives an SRv6
packet whose Segment Left (SL) is equal to 0. In this case, the End
Behavior (which accepts only packets with SL >= 1) discards the packet and
increases the error counter.
This information can be leveraged by the network operator for
troubleshooting. Indeed, the error counter is telling the user that the
packet:

(i) arrived at the node;
(ii) the packet has been taken into account by the SRv6 End behavior;
(iii) but an error has occurred during the processing.

The error (iii) could be caused by different reasons, such as wrong route
settings on the node or due to an invalid SID List carried by the SRv6
packet. Anyway, the error counter is used to exclude that the packet did
not arrive at the node or it has not been processed by the behavior at
all.

Turning on/off counters for SRv6 Behaviors
------------------------------------------

Each SRv6 Behavior instance can be configured, at the time of its creation,
to make use of counters.
This is done through iproute2 which allows the user to create an SRv6
Behavior instance specifying the optional "count" attribute as shown in the
following example:

$ ip -6 route add 2001:db8::1 encap seg6local action End count dev eth0

per-behavior counters can be shown by adding "-s" to the iproute2 command
line, i.e.:

$ ip -s -6 route show 2001:db8::1
2001:db8::1 encap seg6local action End packets 0 bytes 0 errors 0 dev eth0

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Impact of counters for SRv6 Behaviors on performance
====================================================

To determine the performance impact due to the introduction of counters in
the SRv6 Behavior subsystem, we have carried out extensive tests.

We chose to test the throughput achieved by the SRv6 End.DX2 Behavior
because, among all the other behaviors implemented so far, it reaches the
highest throughput which is around 1.5 Mpps (per core at 2.4 GHz on a
Xeon(R) CPU E5-2630 v3) on kernel 5.12-rc2 using packets of size ~ 100
bytes.

Three different tests were conducted in order to evaluate the overall
throughput of the SRv6 End.DX2 Behavior in the following scenarios:

1) vanilla kernel (without the SRv6 Behavior counters patch) and a single
instance of an SRv6 End.DX2 Behavior;
2) patched kernel with SRv6 Behavior counters and a single instance of
an SRv6 End.DX2 Behavior with counters turned off;
3) patched kernel with SRv6 Behavior counters and a single instance of
SRv6 End.DX2 Behavior with counters turned on.

All tests were performed on a testbed deployed on the CloudLab facilities
[2], a flexible infrastructure dedicated to scientific research on the
future of Cloud Computing.

Results of tests are shown in the following table:

Scenario (1): average 1504764,81 pps (~1504,76 kpps); std. dev 3956,82 pps
Scenario (2): average 1501469,78 pps (~1501,47 kpps); std. dev 2979,85 pps
Scenario (3): average 1501315,13 pps (~1501,32 kpps); std. dev 2956,00 pps

As can be observed, throughputs achieved in scenarios (2),(3) did not
suffer any observable degradation compared to scenario (1).

Thanks to Jakub Kicinski and David Ahern for their valuable suggestions
and comments provided during the discussion of the proposed RFCs.

[2] https://www.cloudlab.us

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: seg6: trivial fix of a spelling mistake in comment

There is a comment spelling mistake "interfarence" -> "interference" in
function parse_nla_action(). Fix it.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: ignore routing header with segments left equal to 0

When there are 2 segments routing header, after an End.B6 action
for example, the second SRH will never be handled by an action, packet will
be dropped when the first SRH has segments left equal to 0.
For actions that doesn't perform decapsulation (currently: End, End.X,
End.T, End.B6, End.B6.Encaps), this patch adds the IP6_FH_F_SKIP_RH flag
in arguments for ipv6_find_hdr().

Signed-off-by: Julien Massonneau <julien.massonneau@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: fool-proof the processing of SRv6 behavior attributes

The set of required attributes for a given SRv6 behavior is identified
using a bitmap stored in an unsigned long, since the initial design of SRv6
networking in Linux. Recently the same approach has been used for
identifying the optional attributes.

However, the number of attributes supported by SRv6 behaviors depends on
the size of the unsigned long type which changes with the architecture.
Indeed, on a 64-bit architecture, an SRv6 behavior can support up to 64
attributes while on a 32-bit architecture it can support at most 32
attributes.

To fool-proof the processing of SRv6 behaviors we verify, at compile time,
that the set of all supported SRv6 attributes can be encoded into a bitmap
stored in an unsigned long. Otherwise, kernel build fails forcing
developers to reconsider adding a new attribute or extend the total
number of supported attributes by the SRv6 behaviors.

Moreover, we replace all patterns (1 << i) with the macro SEG6_F_ATTR(i) in
order to address potential overflow issues caused by 32-bit signed
arithmetic.

Thanks to Colin Ian King for catching the overflow problem, providing a
solution and inspiring this patch.
Thanks to Jakub Kicinski for his useful suggestions during the design of
this patch.

v2:
- remove the SEG6_LOCAL_MAX_SUPP which is not strictly needed: it can
be derived from the unsigned long type. Thanks to David Ahern for
pointing it out.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20210206170934.5982-1-andrea.mayer@uniroma2.it
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: add VRF support for SRv6 End.DT6 behavior

SRv6 End.DT6 is defined in the SRv6 Network Programming [1].

The Linux kernel already offers an implementation of the SRv6
End.DT6 behavior which permits IPv6 L3 VPNs over SRv6 networks. This
implementation is not particularly suitable in contexts where we need to
deploy IPv6 L3 VPNs among different tenants which share the same network
address schemes. The underlying problem lies in the fact that the
current version of DT6 (called legacy DT6 from now on) needs a complex
configuration to be applied on routers which requires ad-hoc routes and
routing policy rules to ensure the correct isolation of tenants.

Consequently, a new implementation of DT6 has been introduced with the
aim of simplifying the construction of IPv6 L3 VPN services in the
multi-tenant environment using SRv6 networks. To accomplish this task,
we reused the same VRF infrastructure and SRv6 core components already
exploited for implementing the SRv6 End.DT4 behavior.

Currently the two End.DT6 implementations coexist seamlessly and can be
used depending on the context and the user preferences. So, in order to
support both versions of DT6 a new attribute (vrftable) has been
introduced which allows us to differentiate the implementation of the
behavior to be used.

A SRv6 End.DT6 legacy behavior is still instantiated using a command
like the following one:

$ ip -6 route add 2001:db8::1 encap seg6local action End.DT6 table 100 dev eth0

While to instantiate the SRv6 End.DT6 in VRF mode, the command is still
pretty straight forward:

$ ip -6 route add 2001:db8::1 encap seg6local action End.DT6 vrftable 100 dev eth0.

Obviously as in the case of SRv6 End.DT4, the VRF strict_mode parameter
must be set (net.vrf.strict_mode=1) and the VRF associated with table
100 must exist.

Please note that the instances of SRv6 End.DT6 legacy and End.DT6 VRF
mode can coexist in the same system/configuration without problems.

[1] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: add support for the SRv6 End.DT4 behavior

SRv6 End.DT4 is defined in the SRv6 Network Programming [1].

The SRv6 End.DT4 is used to implement IPv4 L3VPN use-cases in
multi-tenants environments. It decapsulates the received packets and it
performs IPv4 routing lookup in the routing table of the tenant.

The SRv6 End.DT4 Linux implementation leverages a VRF device in order to
force the routing lookup into the associated routing table.

To make the End.DT4 work properly, it must be guaranteed that the routing
table used for routing lookup operations is bound to one and only one
VRF during the tunnel creation. Such constraint has to be enforced by
enabling the VRF strict_mode sysctl parameter, i.e:
$ sysctl -wq net.vrf.strict_mode=1.

At JANOG44, LINE corporation presented their multi-tenant DC architecture
using SRv6 [2]. In the slides, they reported that the Linux kernel is
missing the support of SRv6 End.DT4 behavior.

The SRv6 End.DT4 behavior can be instantiated using a command similar to
the following:

$ ip route add 2001:db8::1 encap seg6local action End.DT4 vrftable 100 dev eth0

We introduce the "vrftable" extension in iproute2 in a following patch.

[1] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming
[2] https://speakerdeck.com/line_developers/line-data-center-networking-with-srv6

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: add callbacks for customizing the creation/destruction of a behavior

We introduce two callbacks used for customizing the creation/destruction of
a SRv6 behavior. Such callbacks are defined in the new struct
seg6_local_lwtunnel_ops and hereafter we provide a brief description of
them:

- build_state(...): used for calling the custom constructor of the
behavior during its initialization phase and after all the attributes
have been parsed successfully;

- destroy_state(...): used for calling the custom destructor of the
behavior before it is completely destroyed.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: add support for optional attributes in SRv6 behaviors

Before this patch, each SRv6 behavior specifies a set of required
attributes that must be provided by the userspace application when such
behavior is going to be instantiated. If at least one of the required
attributes is not provided, the creation of the behavior fails.

The SRv6 behavior framework lacks a way to manage optional attributes.
By definition, an optional attribute for a SRv6 behavior consists of an
attribute which may or may not be provided by the userspace. Therefore,
if an optional attribute is missing (and thus not supplied by the user)
the creation of the behavior goes ahead without any issue.

This patch explicitly differentiates the required attributes from the
optional attributes. In particular, each behavior can declare a set of
required attributes and a set of optional ones.

The semantic of the required attributes remains *totally* unaffected by
this patch. The introduction of the optional attributes does NOT impact
on the backward compatibility of the existing SRv6 behaviors.

It is essential to note that if an (optional or required) attribute is
supplied to a SRv6 behavior which does not expect it, the behavior
simply discards such attribute without generating any error or warning.
This operating mode remained unchanged both before and after the
introduction of the optional attributes extension.

The optional attributes are one of the key components used to implement
the SRv6 End.DT6 behavior based on the Virtual Routing and Forwarding
(VRF) framework. The optional attributes make possible the coexistence
of the already existing SRv6 End.DT6 implementation with the new SRv6
End.DT6 VRF-based implementation without breaking any backward
compatibility. Further details on the SRv6 End.DT6 behavior (VRF mode)
are reported in subsequent patches.

From the userspace point of view, the support for optional attributes DO
NOT require any changes to the userspace applications, i.e: iproute2
unless new attributes (required or optional) are needed.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: improve management of behavior attributes

Depending on the attribute (i.e.: SEG6_LOCAL_SRH, SEG6_LOCAL_TABLE, etc),
the parse() callback performs some validity checks on the provided input
and updates the tunnel state (slwt) with the result of the parsing
operation. However, an attribute may also need to reserve some additional
resources (i.e.: memory or setting up an eBPF program) in the parse()
callback to complete the parsing operation.

The parse() callbacks are invoked by the parse_nla_action() for each
attribute belonging to a specific behavior. Given a behavior with N
attributes, if the parsing of the i-th attribute fails, the
parse_nla_action() returns immediately with an error. Nonetheless, the
resources acquired during the parsing of the i-1 attributes are not freed
by the parse_nla_action().

Attributes which acquire resources must release them *in an explicit way*
in both the seg6_local_{build/destroy}_state(). However, adding a new
attribute of this type requires changes to
seg6_local_{build/destroy}_state() to release the resources correctly.

The seg6local infrastructure still lacks a simple and structured way to
release the resources acquired in the parse() operations.

We introduced a new callback in the struct seg6_action_param named
destroy(). This callback releases any resource which may have been acquired
in the parse() counterpart. Each attribute may or may not implement the
destroy() callback depending on whether it needs to free some acquired
resources.

The destroy() callback comes with several of advantages:

1) we can have many attributes as we want for a given behavior with no
need to explicitly free the taken resources;

2) As in case of the seg6_local_build_state(), the
seg6_local_destroy_state() does not need to handle the release of
resources directly. Indeed, it calls the destroy_attrs() function which
is in charge of calling the destroy() callback for every set attribute.
We do not need to patch seg6_local_{build/destroy}_state() anymore as
we add new attributes;

3) the code is more readable and better structured. Indeed, all the
information needed to handle a given attribute are contained in only
one place;

4) it facilitates the integration with new features introduced in further
patches.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

seg6: fix seg6_validate_srh() to avoid slab-out-of-bounds

The seg6_validate_srh() is used to validate SRH for three cases:

case1: SRH of data-plane SRv6 packets to be processed by the Linux kernel.
Case2: SRH of the netlink message received from user-space (iproute2)
Case3: SRH injected into packets through setsockopt

In case1, the SRH can be encoded in the Reduced way (i.e., first SID is
carried in DA only and not represented as SID in the SRH) and the
seg6_validate_srh() now handles this case correctly.

In case2 and case3, the SRH shouldn’t be encoded in the Reduced way
otherwise we lose the first segment (i.e., the first hop).

The current implementation of the seg6_validate_srh() allow SRH of case2
and case3 to be encoded in the Reduced way. This leads a slab-out-of-bounds
problem.

This patch verifies SRH of case1, case2 and case3. Allowing case1 to be
reduced while preventing SRH of case2 and case3 from being reduced .

Reported-by: syzbot+e8c028b62439eac42073@syzkaller.appspotmail.com
Reported-by: YueHaibing <yuehaibing@huawei.com>
Fixes: 0cb7498f234e ("seg6: fix SRH processing to comply with RFC8754")
Signed-off-by: Ahmed Abdelsalam <ahabdels@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: add net available in build_state

The build_state callback of lwtunnel doesn't contain the net namespace
structure yet. This patch will add it so we can check on specific
address configuration at creation time of rpl source routes.

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

seg6: fix SRv6 L2 tunnels to use IANA-assigned protocol number

The Internet Assigned Numbers Authority (IANA) has recently assigned
a protocol number value of 143 for Ethernet [1].

Before this assignment, encapsulation mechanisms such as Segment Routing
used the IPv6-NoNxt protocol number (59) to indicate that the encapsulated
payload is an Ethernet frame.

In this patch, we add the definition of the Ethernet protocol number to the
kernel headers and update the SRv6 L2 tunnels to use it.

[1] https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml

Signed-off-by: Paolo Lungaroni <paolo.lungaroni@cnit.it>
Reviewed-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Acked-by: Ahmed Abdelsalam <ahmed.abdelsalam@gssi.it>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sr: remove SKB_GSO_IPXIP6 on End.D* actions

After LRO/GRO is applied, SRv6 encapsulated packets have
SKB_GSO_IPXIP6 feature flag, and this flag must be removed right after
decapulation procedure.

Currently, SKB_GSO_IPXIP6 flag is not removed on End.D* actions, which
creates inconsistent packet state, that is, a normal TCP/IP packets
have the SKB_GSO_IPXIP6 flag. This behavior can cause unexpected
fallback to GSO on routing to netdevices that do not support
SKB_GSO_IPXIP6. For example, on inter-VRF forwarding, decapsulated
packets separated into small packets by GSO because VRF devices do not
support TSO for packets with SKB_GSO_IPXIP6 flag, and this degrades
forwarding performance.

This patch removes encapsulation related GSO flags from the skb right
after the End.D* action is applied.

Fixes: d7a669dd2f8b ("ipv6: sr: add helper functions for seg6local")
Signed-off-by: Yuki Taguchi <tagyounit@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: allow local packet processing for SRv6 End.DT6 behavior

End.DT6 behavior makes use of seg6_lookup_nexthop() function which drops
all packets that are destined to be locally processed. However, DT* should
be able to deliver decapsulated packets that are destined to local
addresses. Function seg6_lookup_nexthop() is also used by DX6, so in order
to maintain compatibility I created another routing helper function which
is called seg6_lookup_any_nexthop(). This function is able to take into
account both packets that have to be processed locally and the ones that
are destined to be forwarded directly to another machine. Hence,
seg6_lookup_any_nexthop() is used in DT6 rather than seg6_lookup_nexthop()
to allow local delivery.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: fix skb transport_header after decap_and_validate()

in the receive path (more precisely in ip6_rcv_core()) the
skb->transport_header is set to skb->network_header + sizeof(*hdr). As a
consequence, after routing operations, destination input expects to find
skb->transport_header correctly set to the next protocol (or extension
header) that follows the network protocol. However, decap behaviors (DX*,
DT*) remove the outer IPv6 and SRH extension and do not set again the
skb->transport_header pointer correctly. For this reason, the patch sets
the skb->transport_header to the skb->network_header + sizeof(hdr) in each
DX* and DT* behavior.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>

seg6: fix srh pointer in get_srh()

pskb_may_pull may change pointers in header. For this reason, it is
mandatory to reload any pointer that points into skb header.

Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

netlink: make validation more configurable for future strictness

We currently have two levels of strict validation:

1) liberal (default)
- undefined (type >= max) & NLA_UNSPEC attributes accepted
- attribute length >= expected accepted
- garbage at end of message accepted
2) strict (opt-in)
- NLA_UNSPEC attributes accepted
- attribute length >= expected accepted

Split out parsing strictness into four different options:
* TRAILING - check that there's no trailing data after parsing
attributes (in message or nested)
* MAXTYPE - reject attrs > max known type
* UNSPEC - reject attributes with NLA_UNSPEC policy entries
* STRICT_ATTRS - strictly validate attribute size

The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().

Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.

We end up with the following renames:
* nla_parse -> nla_parse_deprecated
* nla_parse_strict -> nla_parse_deprecated_strict
* nlmsg_parse -> nlmsg_parse_deprecated
* nlmsg_parse_strict -> nlmsg_parse_deprecated_strict
* nla_parse_nested -> nla_parse_nested_deprecated
* nla_validate_nested -> nla_validate_nested_deprecated

Using spatch, of course:
@@
expression TB, MAX, HEAD, LEN, POL, EXT;
@@
-nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
+nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

@@
expression TB, MAX, NLA, POL, EXT;
@@
-nla_parse_nested(TB, MAX, NLA, POL, EXT)
+nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

@@
expression START, MAX, POL, EXT;
@@
-nla_validate_nested(START, MAX, POL, EXT)
+nla_validate_nested_deprecated(START, MAX, POL, EXT)

@@
expression NLH, HDRLEN, MAX, POL, EXT;
@@
-nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
+nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.

Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.

Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.

In effect then, this adds fully strict validation for any new command.

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

netlink: make nla_nest_start() add NLA_F_NESTED flag

Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.

Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().

Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:

@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)

@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

bpf: add End.DT6 action to bpf_lwt_seg6_action helper

The seg6local LWT provides the End.DT6 action, which allows to
decapsulate an outer IPv6 header containing a Segment Routing Header
(SRH), full specification is available here:

https://tools.ietf.org/html/draft-filsfils-spring-srv6-network-programming-05

This patch adds this action now to the seg6local BPF
interface. Since it is not mandatory that the inner IPv6 header also
contains a SRH, seg6_bpf_srh_state has been extended with a pointer to
a possible SRH of the outermost IPv6 header. This helps assessing if the
validation must be triggered or not, and avoids some calls to
ipv6_find_hdr.

v3: s/1/true, s/0/false for boolean values
v2: - changed true/false -> 1/0
- preempt_enable no longer called in first conditional block

Signed-off-by: Mathieu Xhonneux <m.xhonneux@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

ipv6: sr: Use kmemdup instead of duplicating it in parse_nla_srh

Replace calls to kmalloc followed by a memcpy with a direct call to
kmemdup.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sr: Add seg6local action End.BPF

This patch adds the End.BPF action to the LWT seg6local infrastructure.
This action works like any other seg6local End action, meaning that an IPv6
header with SRH is needed, whose DA has to be equal to the SID of the
action. It will also advance the SRH to the next segment, the BPF program
does not have to take care of this.

Since the BPF program may not be a source of instability in the kernel, it
is important to ensure that the integrity of the packet is maintained
before yielding it back to the IPv6 layer. The hook hence keeps track if
the SRH has been altered through the helpers, and re-validates its
content if needed with seg6_validate_srh. The state kept for validation is
stored in a per-CPU buffer. The BPF program is not allowed to directly
write into the packet, and only some fields of the SRH can be altered
through the helper bpf_lwt_seg6_store_bytes.

Performances profiling has shown that the SRH re-validation does not induce
a significant overhead. If the altered SRH is deemed as invalid, the packet
is dropped.

This validation is also done before executing any action through
bpf_lwt_seg6_action, and will not be performed again if the SRH is not
modified after calling the action.

The BPF program may return 3 types of return codes:
- BPF_OK: the End.BPF action will look up the next destination through
seg6_lookup_nexthop.
- BPF_REDIRECT: if an action has been executed through the
bpf_lwt_seg6_action helper, the BPF program should return this
value, as the skb's destination is already set and the default
lookup should not be performed.
- BPF_DROP : the packet will be dropped.

Signed-off-by: Mathieu Xhonneux <m.xhonneux@gmail.com>
Acked-by: David Lebrun <dlebrun@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

bpf: Add IPv6 Segment Routing helpers

The BPF seg6local hook should be powerful enough to enable users to
implement most of the use-cases one could think of. After some thinking,
we figured out that the following actions should be possible on a SRv6
packet, requiring 3 specific helpers :
- bpf_lwt_seg6_store_bytes: Modify non-sensitive fields of the SRH
- bpf_lwt_seg6_adjust_srh: Allow to grow or shrink a SRH
(to add/delete TLVs)
- bpf_lwt_seg6_action: Apply some SRv6 network programming actions
(specifically End.X, End.T, End.B6 and
End.B6.Encap)

The specifications of these helpers are provided in the patch (see
include/uapi/linux/bpf.h).

The non-sensitive fields of the SRH are the following : flags, tag and
TLVs. The other fields can not be modified, to maintain the SRH
integrity. Flags, tag and TLVs can easily be modified as their validity
can be checked afterwards via seg6_validate_srh. It is not allowed to
modify the segments directly. If one wants to add segments on the path,
he should stack a new SRH using the End.B6 action via
bpf_lwt_seg6_action.

Growing, shrinking or editing TLVs via the helpers will flag the SRH as
invalid, and it will have to be re-validated before re-entering the IPv6
layer. This flag is stored in a per-CPU buffer, along with the current
header length in bytes.

Storing the SRH len in bytes in the control block is mandatory when using
bpf_lwt_seg6_adjust_srh. The Header Ext. Length field contains the SRH
len rounded to 8 bytes (a padding TLV can be inserted to ensure the 8-bytes
boundary). When adding/deleting TLVs within the BPF program, the SRH may
temporary be in an invalid state where its length cannot be rounded to 8
bytes without remainder, hence the need to store the length in bytes
separately. The caller of the BPF program can then ensure that the SRH's
final length is valid using this value. Again, a final SRH modified by a
BPF program which doesn’t respect the 8-bytes boundary will be discarded
as it will be considered as invalid.

Finally, a fourth helper is provided, bpf_lwt_push_encap, which is
available from the LWT BPF IN hook, but not from the seg6local BPF one.
This helper allows to encapsulate a Segment Routing Header (either with
a new outer IPv6 header, or by inlining it directly in the existing IPv6
header) into a non-SRv6 packet. This helper is required if we want to
offer the possibility to dynamically encapsulate a SRH for non-SRv6 packet,
as the BPF seg6local hook only works on traffic already containing a SRH.
This is the BPF equivalent of the seg6 LWT infrastructure, which achieves
the same purpose but with a static SRH per route.

These helpers require CONFIG_IPV6=y (and not =m).

Signed-off-by: Mathieu Xhonneux <m.xhonneux@gmail.com>
Acked-by: David Lebrun <dlebrun@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

ipv6: sr: export function lookup_nexthop

The function lookup_nexthop is essential to implement most of the seg6local
actions. As we want to provide a BPF helper allowing to apply some of these
actions on the packet being processed, the helper should be able to call
this function, hence the need to make it public.

Moreover, if one argument is incorrect or if the next hop can not be found,
an error should be returned by the BPF helper so the BPF program can adapt
its processing of the packet (return an error, properly force the drop,
...). This patch hence makes this function return dst->error to indicate a
possible error.

Signed-off-by: Mathieu Xhonneux <m.xhonneux@gmail.com>
Acked-by: David Lebrun <dlebrun@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

net/ipv6: Pass skb to route lookup

IPv6 does path selection for multipath routes deep in the lookup
functions. The next patch adds L4 hash option and needs the skb
for the forward path. To get the skb to the relevant FIB lookup
functions it needs to go through the fib rules layer, so add a
lookup_data argument to the fib_lookup_arg struct.

Signed-off-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: use ARRAY_SIZE for array sizing calculation on array seg6_action_table

Use the ARRAY_SIZE macro on array seg6_action_table to determine size of
the array. Improvement suggested by coccinelle.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sr: remove duplicate routing header type check

As seg6_validate_srh() already checks that the Routing Header type is
correct, it is not necessary to do it again in get_srh().

Fixes: 5829d70b ("ipv6: sr: fix get_srh() to comply with IPv6 standard "RFC 8200")
Signed-off-by: David Lebrun <dlebrun@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sr: fix get_srh() to comply with IPv6 standard "RFC 8200"

IPv6 packet may carry more than one extension header, and IPv6 nodes must
accept and attempt to process extension headers in any order and occurring
any number of times in the same packet. Hence, there should be no
assumption that Segment Routing extension header is to appear immediately
after the IPv6 header.

Moreover, section 4.1 of RFC 8200 gives a recommendation on the order of
appearance of those extension headers within an IPv6 packet. According to
this recommendation, Segment Routing extension header should appear after
Hop-by-Hop and Destination Options headers (if they present).

This patch fixes the get_srh(), so it gets the segment routing header
regardless of its position in the chain of the extension headers in IPv6
packet, and makes sure that the IPv6 routing extension header is of Type 4.

Signed-off-by: Ahmed Abdelsalam <amsalam20@gmail.com>
Acked-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

ipv6: sr: implement additional seg6local actions

This patch implements the following seg6local actions.

- SEG6_LOCAL_ACTION_END_T: regular SRH processing and forward to the
next-hop looked up in the specified routing table.

- SEG6_LOCAL_ACTION_END_DX2: decapsulate an L2 frame and forward it to
the specified network interface.

- SEG6_LOCAL_ACTION_END_DX4: decapsulate an IPv4 packet and forward it,
possibly to the specified next-hop.

- SEG6_LOCAL_ACTION_END_DT6: decapsulate an IPv6 packet and forward it
to the next-hop looked up in the specified routing table.

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

ipv6: sr: add helper functions for seg6local

This patch adds three helper functions to be used with the seg6local packet
processing actions.

The decap_and_validate() function will be used by the End.D* actions, that
decapsulate an SR-enabled packet.

The advance_nextseg() function applies the fundamental operations to update
an SRH for the next segment.

The lookup_nexthop() function helps select the next-hop for the processed
SR packets. It supports an optional next-hop address to route the packet
specifically through it, and an optional routing table to use.

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

ipv6: sr: enforce IPv6 packets for seg6local lwt

This patch ensures that the seg6local lightweight tunnel is used solely
with IPv6 routes and processes only IPv6 packets.

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

ipv6: sr: add support for ip4ip6 encapsulation

This patch enables the SRv6 encapsulation mode to carry an IPv4 payload.
All the infrastructure was already present, I just had to add a parameter
to seg6_do_srh_encap() to specify the inner packet protocol, and perform
some additional checks.

Usage example:
ip route add 1.2.3.4 encap seg6 mode encap segs fc00::1,fc00::2 dev eth0

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

ipv6: sr: implement several seg6local actions

This patch implements the following seg6local actions.

- SEG6_LOCAL_ACTION_END: regular SRH processing. The DA of the packet
is updated to the next segment and forwarded accordingly.

- SEG6_LOCAL_ACTION_END_X: same as above, except that the packet is
forwarded to the specified IPv6 next-hop.

- SEG6_LOCAL_ACTION_END_DX6: decapsulate the packet and forward to
inner IPv6 packet to the specified IPv6 next-hop.

- SEG6_LOCAL_ACTION_END_B6: insert the specified SRH directly after
the IPv6 header of the packet.

- SEG6_LOCAL_ACTION_END_B6_ENCAP: encapsulate the packet within
an outer IPv6 header, containing the specified SRH.

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

ipv6: sr: add rtnetlink functions for seg6local action parameters

This patch adds the necessary functions to parse, fill, and compare
seg6local rtnetlink attributes, for all defined action parameters.

- The SRH parameter defines an SRH to be inserted or encapsulated.
- The TABLE parameter defines the table to use for the route lookup of
the next segment or the inner decapsulated packet.
- The NH4 parameter defines the IPv4 next-hop for an inner decapsulated
IPv4 packet.
- The NH6 parameter defines the IPv6 next-hop for the next segment or
for an inner decapsulated IPv6 packet
- The IIF parameter defines an ingress interface index.
- The OIF parameter defines an egress interface index.

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

ipv6: sr: define core operations for seg6local lightweight tunnel

This patch implements a new type of lightweight tunnel named seg6local.
A seg6local lwt is defined by a type of action and a set of parameters.
The action represents the operation to perform on the packets matching the
lwt's route, and is not necessarily an encapsulation. The set of parameters
are arguments for the processing function.

Each action is defined in a struct seg6_action_desc within
seg6_action_table[]. This structure contains the action, mandatory
attributes, the processing function, and a static headroom size required by
the action. The mandatory attributes are encoded as a bitmask field. The
static headroom is set to a non-zero value when the processing function
always add a constant number of bytes to the skb (e.g. the header size for
encapsulations).

To facilitate rtnetlink-related operations such as parsing, fill_encap,
and cmp_encap, each type of action parameter is associated to three
function pointers, in seg6_action_params[].

All actions defined in seg6_local.h are detailed in [1].

[1] https://tools.ietf.org/html/draft-filsfils-spring-srv6-network-programming-01

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