[PATCH] docs: bpf: Added more extension example
From: UjjaL Roy <hidden>
Date: 2021-07-07 17:40:38
Also in:
bpf, linux-riscv, lkml, netdev
Subsystem:
bpf [general] (safe dynamic programs and tools), documentation, networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Jonathan Corbet, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: "Roy, UjjaL" <redacted> After reading this document observed that for new users it is hard to find an example of "extension" easily. So, added a new heading for extensions for better readability. Now, the new readers can easily identify "extension" examples. Also, added one more example of filtering interface index. Signed-off-by: Roy, UjjaL <redacted> --- Documentation/networking/filter.rst | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/Documentation/networking/filter.rst b/Documentation/networking/filter.rst
index 3e2221f4abe4..5f13905b12e0 100644
--- a/Documentation/networking/filter.rst
+++ b/Documentation/networking/filter.rst@@ -320,13 +320,6 @@ Examples for low-level BPF: ret #-1 drop: ret #0 -**(Accelerated) VLAN w/ id 10**:: - - ld vlan_tci - jneq #10, drop - ret #-1 - drop: ret #0 - **icmp random packet sampling, 1 in 4**:: ldh [12]
@@ -358,6 +351,22 @@ Examples for low-level BPF: bad: ret #0 /* SECCOMP_RET_KILL_THREAD */ good: ret #0x7fff0000 /* SECCOMP_RET_ALLOW */ +Examples for low-level BPF extension: + +**Packet for interface index 13**:: + + ld ifidx + jneq #13, drop + ret #-1 + drop: ret #0 + +**(Accelerated) VLAN w/ id 10**:: + + ld vlan_tci + jneq #10, drop + ret #-1 + drop: ret #0 + The above example code can be placed into a file (here called "foo"), and then be passed to the bpf_asm tool for generating opcodes, output that xt_bpf and cls_bpf understands and can directly be loaded with. Example with above
--
2.17.1