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| author | Kees Cook <kees+treewide@kernel.org> | 2026-09-02 15:31:14 -0700 |
|---|---|---|
| committer | Kees Cook <kees@kernel.org> | 2026-09-04 21:37:00 -0700 |
| commit | 3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d (patch) | |
| tree | c65086f9bdcd48c6360fb7cb4598bca084da1f32 /Documentation/networking/vxlan.rst | |
| download | linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.tar.gz linux-stable-3a2c4d55e32ad65efebdb6de44eef3bfa08bb49d.zip | |
treewide: refresh kmalloc_obj() conversionsgrafted
This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci
This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.
Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.
Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <kees+treewide@kernel.org>
Diffstat (limited to 'Documentation/networking/vxlan.rst')
| -rw-r--r-- | Documentation/networking/vxlan.rst | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/Documentation/networking/vxlan.rst b/Documentation/networking/vxlan.rst new file mode 100644 index 000000000..2759dc1cc --- /dev/null +++ b/Documentation/networking/vxlan.rst @@ -0,0 +1,88 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================================== +Virtual eXtensible Local Area Networking documentation +====================================================== + +The VXLAN protocol is a tunnelling protocol designed to solve the +problem of limited VLAN IDs (4096) in IEEE 802.1q. With VXLAN the +size of the identifier is expanded to 24 bits (16777216). + +VXLAN is described by IETF RFC 7348, and has been implemented by a +number of vendors. The protocol runs over UDP using a single +destination port. This document describes the Linux kernel tunnel +device, there is also a separate implementation of VXLAN for +Openvswitch. + +Unlike most tunnels, a VXLAN is a 1 to N network, not just point to +point. A VXLAN device can learn the IP address of the other endpoint +either dynamically in a manner similar to a learning bridge, or make +use of statically-configured forwarding entries. + +The management of vxlan is done in a manner similar to its two closest +neighbors GRE and VLAN. Configuring VXLAN requires the version of +iproute2 that matches the kernel release where VXLAN was first merged +upstream. + +1. Create vxlan device:: + + # ip link add vxlan0 type vxlan id 42 group 239.1.1.1 dev eth1 dstport 4789 + +This creates a new device named vxlan0. The device uses the multicast +group 239.1.1.1 over eth1 to handle traffic for which there is no +entry in the forwarding table. The destination port number is set to +the IANA-assigned value of 4789. The Linux implementation of VXLAN +pre-dates the IANA's selection of a standard destination port number +and uses the Linux-selected value by default to maintain backwards +compatibility. + +2. Delete vxlan device:: + + # ip link delete vxlan0 + +3. Show vxlan info:: + + # ip -d link show vxlan0 + +It is possible to create, destroy and display the vxlan +forwarding table using the new bridge command. + +1. Create forwarding table entry:: + + # bridge fdb add to 00:17:42:8a:b4:05 dst 192.19.0.2 dev vxlan0 + +2. Delete forwarding table entry:: + + # bridge fdb delete 00:17:42:8a:b4:05 dev vxlan0 + +3. Show forwarding table:: + + # bridge fdb show dev vxlan0 + +The following NIC features may indicate support for UDP tunnel-related +offloads (most commonly VXLAN features, but support for a particular +encapsulation protocol is NIC specific): + + - `tx-udp_tnl-segmentation` + - `tx-udp_tnl-csum-segmentation` + ability to perform TCP segmentation offload of UDP encapsulated frames + + - `rx-udp_tunnel-port-offload` + receive side parsing of UDP encapsulated frames which allows NICs to + perform protocol-aware offloads, like checksum validation offload of + inner frames (only needed by NICs without protocol-agnostic offloads) + +For devices supporting `rx-udp_tunnel-port-offload` the list of currently +offloaded ports can be interrogated with `ethtool`:: + + $ ethtool --show-tunnels eth0 + Tunnel information for eth0: + UDP port table 0: + Size: 4 + Types: vxlan + No entries + UDP port table 1: + Size: 4 + Types: geneve, vxlan-gpe + Entries (1): + port 1230, vxlan-gpe |
