linux/samples
Jesper Dangaard Brouer 36e04a2d78 samples/bpf: xdp2skb_meta shows transferring info from XDP to SKB
Creating a bpf sample that shows howto use the XDP 'data_meta'
infrastructure, created by Daniel Borkmann.  Very few drivers support
this feature, but I wanted a functional sample to begin with, when
working on adding driver support.

XDP data_meta is about creating a communication channel between BPF
programs.  This can be XDP tail-progs, but also other SKB based BPF
hooks, like in this case the TC clsact hook. In this sample I show
that XDP can store info named "mark", and TC/clsact chooses to use
this info and store it into the skb->mark.

It is a bit annoying that XDP and TC samples uses different tools/libs
when attaching their BPF hooks.  As the XDP and TC programs need to
cooperate and agree on a struct-layout, it is best/easiest if the two
programs can be contained within the same BPF restricted-C file.

As the bpf-loader, I choose to not use bpf_load.c (or libbpf), but
instead wrote a bash shell scripted named xdp2skb_meta.sh, which
demonstrate howto use the iproute cmdline tools 'tc' and 'ip' for
loading BPF programs.  To make it easy for first time users, the shell
script have command line parsing, and support --verbose and --dry-run
mode, if you just want to see/learn the tc+ip command syntax:

 # ./xdp2skb_meta.sh --dev ixgbe2 --dry-run
 # Dry-run mode: enable VERBOSE and don't call TC+IP
 tc qdisc del dev ixgbe2 clsact
 tc qdisc add dev ixgbe2 clsact
 tc filter add dev ixgbe2 ingress prio 1 handle 1 bpf da obj ./xdp2skb_meta_kern.o sec tc_mark
 # Flush XDP on device: ixgbe2
 ip link set dev ixgbe2 xdp off
 ip link set dev ixgbe2 xdp obj ./xdp2skb_meta_kern.o sec xdp_mark

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-01-11 01:02:25 +01:00
..
auxdisplay License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
blackfin samples: move blackfin gptimers-example from Documentation 2016-10-10 07:12:02 -06:00
bpf samples/bpf: xdp2skb_meta shows transferring info from XDP to SKB 2018-01-11 01:02:25 +01:00
configfs configfs: make config_item_type const 2017-10-19 16:15:15 +02:00
connector A relatively calm cycle for the docs tree again. 2017-11-13 08:25:06 -08:00
hidraw kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
hw_breakpoint perf: Add context field to perf_event 2011-07-01 11:06:38 +02:00
kdb kdb: Add kdb kernel module sample 2010-10-29 13:14:39 -05:00
kfifo kfifo: clean up example to not use page_link 2017-07-12 16:26:01 -07:00
kobject samples/kobject: be explicit in the module license 2015-03-25 13:41:42 +01:00
kprobes Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 13:05:08 -08:00
livepatch livepatch: add (un)patch callbacks 2017-10-19 10:08:56 +02:00
mei License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mic/mpssd Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
pktgen Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
rpmsg rpmsg: Allow callback to return errors 2016-09-08 22:15:25 -07:00
seccomp kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
sockmap kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
statx kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
timers License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_events Merge branch 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2017-11-15 10:14:11 -08:00
trace_printk tracing: Add trace_printk sample code 2016-06-20 09:54:21 -04:00
uhid kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
v4l [media] media: v4l2-pci-skeleton: Fix error handling path in 'skeleton_probe()' 2017-10-04 16:55:02 -03:00
vfio-mdev vfio-mdev/samples: make mdev_fops const and static 2017-10-02 12:40:05 -06:00
watchdog License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig livepatch: introduce shadow variable API 2017-09-14 23:06:12 +02:00
Makefile statx: Add a system call to make enhanced file info available 2017-03-02 20:51:15 -05:00