linux/net/bpfilter/Kconfig
Alexei Starovoitov d71fa5c976 bpf: Add kernel module with user mode driver that populates bpffs.
Add kernel module with user mode driver that populates bpffs with
BPF iterators.

$ mount bpffs /my/bpffs/ -t bpf
$ ls -la /my/bpffs/
total 4
drwxrwxrwt  2 root root    0 Jul  2 00:27 .
drwxr-xr-x 19 root root 4096 Jul  2 00:09 ..
-rw-------  1 root root    0 Jul  2 00:27 maps.debug
-rw-------  1 root root    0 Jul  2 00:27 progs.debug

The user mode driver will load BPF Type Formats, create BPF maps, populate BPF
maps, load two BPF programs, attach them to BPF iterators, and finally send two
bpf_link IDs back to the kernel.
The kernel will pin two bpf_links into newly mounted bpffs instance under
names "progs.debug" and "maps.debug". These two files become human readable.

$ cat /my/bpffs/progs.debug
  id name            attached
  11 dump_bpf_map    bpf_iter_bpf_map
  12 dump_bpf_prog   bpf_iter_bpf_prog
  27 test_pkt_access
  32 test_main       test_pkt_access test_pkt_access
  33 test_subprog1   test_pkt_access_subprog1 test_pkt_access
  34 test_subprog2   test_pkt_access_subprog2 test_pkt_access
  35 test_subprog3   test_pkt_access_subprog3 test_pkt_access
  36 new_get_skb_len get_skb_len test_pkt_access
  37 new_get_skb_ifindex get_skb_ifindex test_pkt_access
  38 new_get_constant get_constant test_pkt_access

The BPF program dump_bpf_prog() in iterators.bpf.c is printing this data about
all BPF programs currently loaded in the system. This information is unstable
and will change from kernel to kernel as ".debug" suffix conveys.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200819042759.51280-4-alexei.starovoitov@gmail.com
2020-08-20 16:02:36 +02:00

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# SPDX-License-Identifier: GPL-2.0-only
menuconfig BPFILTER
bool "BPF based packet filtering framework (BPFILTER)"
depends on NET && BPF && INET
select USERMODE_DRIVER
help
This builds experimental bpfilter framework that is aiming to
provide netfilter compatible functionality via BPF
if BPFILTER
config BPFILTER_UMH
tristate "bpfilter kernel module with user mode helper"
depends on CC_CAN_LINK
depends on m || CC_CAN_LINK_STATIC
default m
help
This builds bpfilter kernel module with embedded user mode helper
Note: To compile this as built-in, your toolchain must support
building static binaries, since rootfs isn't mounted at the time
when __init functions are called and do_execv won't be able to find
the elf interpreter.
endif