linux-stable.git/tools/bpf, branch v6.8.2 Linux kernel stable tree tools/resolve_btfids: Fix cross-compilation to non-host endianness 2024-03-26T22:16:40+00:00 Viktor Malik vmalik@redhat.com 2024-02-06T12:46:10+00:00 1134719697cf36a8810c58d63418751ff5e5610b [ Upstream commit 903fad4394666bc23975c93fb58f137ce64b5192 ] The .BTF_ids section is pre-filled with zeroed BTF ID entries during the build and afterwards patched by resolve_btfids with correct values. Since resolve_btfids always writes in host-native endianness, it relies on libelf to do the translation when the target ELF is cross-compiled to a different endianness (this was introduced in commit 61e8aeda9398 ("bpf: Fix libelf endian handling in resolv_btfids")). Unfortunately, the translation will corrupt the flags fields of SET8 entries because these were written during vmlinux compilation and are in the correct endianness already. This will lead to numerous selftests failures such as: $ sudo ./test_verifier 502 502 #502/p sleepable fentry accept FAIL Failed to load prog 'Invalid argument'! bpf_fentry_test1 is not sleepable verification time 34 usec stack depth 0 processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 Summary: 0 PASSED, 0 SKIPPED, 1 FAILED Since it's not possible to instruct libelf to translate just certain values, let's manually bswap the flags (both global and entry flags) in resolve_btfids when needed, so that libelf then translates everything correctly. Fixes: ef2c6f370a63 ("tools/resolve_btfids: Add support for 8-byte BTF sets") Signed-off-by: Viktor Malik <vmalik@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/7b6bff690919555574ce0f13d2a5996cacf7bf69.1707223196.git.vmalik@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 903fad4394666bc23975c93fb58f137ce64b5192 ]

The .BTF_ids section is pre-filled with zeroed BTF ID entries during the
build and afterwards patched by resolve_btfids with correct values.
Since resolve_btfids always writes in host-native endianness, it relies
on libelf to do the translation when the target ELF is cross-compiled to
a different endianness (this was introduced in commit 61e8aeda9398
("bpf: Fix libelf endian handling in resolv_btfids")).

Unfortunately, the translation will corrupt the flags fields of SET8
entries because these were written during vmlinux compilation and are in
the correct endianness already. This will lead to numerous selftests
failures such as:

    $ sudo ./test_verifier 502 502
    #502/p sleepable fentry accept FAIL
    Failed to load prog 'Invalid argument'!
    bpf_fentry_test1 is not sleepable
    verification time 34 usec
    stack depth 0
    processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
    Summary: 0 PASSED, 0 SKIPPED, 1 FAILED

Since it's not possible to instruct libelf to translate just certain
values, let's manually bswap the flags (both global and entry flags) in
resolve_btfids when needed, so that libelf then translates everything
correctly.

Fixes: ef2c6f370a63 ("tools/resolve_btfids: Add support for 8-byte BTF sets")
Signed-off-by: Viktor Malik <vmalik@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/7b6bff690919555574ce0f13d2a5996cacf7bf69.1707223196.git.vmalik@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
tools/resolve_btfids: Refactor set sorting with types from btf_ids.h 2024-03-26T22:16:40+00:00 Viktor Malik vmalik@redhat.com 2024-02-06T12:46:09+00:00 c184613ca3bdb3c56d0f3aec1eafbe1a490e4053 [ Upstream commit 9707ac4fe2f5bac6406d2403f8b8a64d7b3d8e43 ] Instead of using magic offsets to access BTF ID set data, leverage types from btf_ids.h (btf_id_set and btf_id_set8) which define the actual layout of the data. Thanks to this change, set sorting should also continue working if the layout changes. This requires to sync the definition of 'struct btf_id_set8' from include/linux/btf_ids.h to tools/include/linux/btf_ids.h. We don't sync the rest of the file at the moment, b/c that would require to also sync multiple dependent headers and we don't need any other defs from btf_ids.h. Signed-off-by: Viktor Malik <vmalik@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Daniel Xu <dxu@dxuuu.xyz> Link: https://lore.kernel.org/bpf/ff7f062ddf6a00815fda3087957c4ce667f50532.1707223196.git.vmalik@redhat.com Stable-dep-of: 903fad439466 ("tools/resolve_btfids: Fix cross-compilation to non-host endianness") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 9707ac4fe2f5bac6406d2403f8b8a64d7b3d8e43 ]

Instead of using magic offsets to access BTF ID set data, leverage types
from btf_ids.h (btf_id_set and btf_id_set8) which define the actual
layout of the data. Thanks to this change, set sorting should also
continue working if the layout changes.

This requires to sync the definition of 'struct btf_id_set8' from
include/linux/btf_ids.h to tools/include/linux/btf_ids.h. We don't sync
the rest of the file at the moment, b/c that would require to also sync
multiple dependent headers and we don't need any other defs from
btf_ids.h.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/bpf/ff7f062ddf6a00815fda3087957c4ce667f50532.1707223196.git.vmalik@redhat.com
Stable-dep-of: 903fad439466 ("tools/resolve_btfids: Fix cross-compilation to non-host endianness")
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpftool: Fix wrong free call in do_show_link 2024-03-26T22:16:33+00:00 Jiri Olsa jolsa@kernel.org 2024-01-19T11:05:00+00:00 78a4c62603f8845b93b0305de1621819980f2308 [ Upstream commit 2adb2e0fcdf3c6d8e28a5a9c33e458e1037ae5ad ] The error path frees wrong array, it should be ref_ctr_offsets. Acked-by: Yafang Shao <laoar.shao@gmail.com> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Fixes: a7795698f8b6 ("bpftool: Add support to display uprobe_multi links") Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20240119110505.400573-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2adb2e0fcdf3c6d8e28a5a9c33e458e1037ae5ad ]

The error path frees wrong array, it should be ref_ctr_offsets.

Acked-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Fixes: a7795698f8b6 ("bpftool: Add support to display uprobe_multi links")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240119110505.400573-4-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpftool: Silence build warning about calloc() 2024-03-26T22:16:33+00:00 Tiezhu Yang yangtiezhu@loongson.cn 2024-01-16T06:19:20+00:00 24fe9e13b2efb1671d01c432f602c49ce7667f91 [ Upstream commit f5f30386c78105cba520e443a6a9ee945ec1d066 ] There exists the following warning when building bpftool: CC prog.o prog.c: In function ‘profile_open_perf_events’: prog.c:2301:24: warning: ‘calloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Wcalloc-transposed-args] 2301 | sizeof(int), obj->rodata->num_cpu * obj->rodata->num_metric); | ^~~ prog.c:2301:24: note: earlier argument should specify number of elements, later size of each element Tested with the latest upstream GCC which contains a new warning option -Wcalloc-transposed-args. The first argument to calloc is documented to be number of elements in array, while the second argument is size of each element, just switch the first and second arguments of calloc() to silence the build warning, compile tested only. Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command") Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240116061920.31172-1-yangtiezhu@loongson.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f5f30386c78105cba520e443a6a9ee945ec1d066 ]

There exists the following warning when building bpftool:

  CC      prog.o
prog.c: In function ‘profile_open_perf_events’:
prog.c:2301:24: warning: ‘calloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
 2301 |                 sizeof(int), obj->rodata->num_cpu * obj->rodata->num_metric);
      |                        ^~~
prog.c:2301:24: note: earlier argument should specify number of elements, later size of each element

Tested with the latest upstream GCC which contains a new warning option
-Wcalloc-transposed-args. The first argument to calloc is documented to
be number of elements in array, while the second argument is size of each
element, just switch the first and second arguments of calloc() to silence
the build warning, compile tested only.

Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20240116061920.31172-1-yangtiezhu@loongson.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpfilter: remove bpfilter 2024-01-04T18:23:10+00:00 Quentin Deslandes qde@naccy.de 2023-12-26T13:07:42+00:00 98e20e5e13d2811898921f999288be7151a11954 bpfilter was supposed to convert iptables filtering rules into BPF programs on the fly, from the kernel, through a usermode helper. The base code for the UMH was introduced in 2018, and couple of attempts (2, 3) tried to introduce the BPF program generate features but were abandoned. bpfilter now sits in a kernel tree unused and unusable, occasionally causing confusion amongst Linux users (4, 5). As bpfilter is now developed in a dedicated repository on GitHub (6), it was suggested a couple of times this year (LSFMM/BPF 2023, LPC 2023) to remove the deprecated kernel part of the project. This is the purpose of this patch. [1]: https://lore.kernel.org/lkml/20180522022230.2492505-1-ast@kernel.org/ [2]: https://lore.kernel.org/bpf/20210829183608.2297877-1-me@ubique.spb.ru/#t [3]: https://lore.kernel.org/lkml/20221224000402.476079-1-qde@naccy.de/ [4]: https://dxuuu.xyz/bpfilter.html [5]: https://github.com/linuxkit/linuxkit/pull/3904 [6]: https://github.com/facebook/bpfilter Signed-off-by: Quentin Deslandes <qde@naccy.de> Link: https://lore.kernel.org/r/20231226130745.465988-1-qde@naccy.de Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
bpfilter was supposed to convert iptables filtering rules into
BPF programs on the fly, from the kernel, through a usermode
helper. The base code for the UMH was introduced in 2018, and
couple of attempts (2, 3) tried to introduce the BPF program
generate features but were abandoned.

bpfilter now sits in a kernel tree unused and unusable, occasionally
causing confusion amongst Linux users (4, 5).

As bpfilter is now developed in a dedicated repository on GitHub (6),
it was suggested a couple of times this year (LSFMM/BPF 2023,
LPC 2023) to remove the deprecated kernel part of the project. This
is the purpose of this patch.

[1]: https://lore.kernel.org/lkml/20180522022230.2492505-1-ast@kernel.org/
[2]: https://lore.kernel.org/bpf/20210829183608.2297877-1-me@ubique.spb.ru/#t
[3]: https://lore.kernel.org/lkml/20221224000402.476079-1-qde@naccy.de/
[4]: https://dxuuu.xyz/bpfilter.html
[5]: https://github.com/linuxkit/linuxkit/pull/3904
[6]: https://github.com/facebook/bpfilter

Signed-off-by: Quentin Deslandes <qde@naccy.de>
Link: https://lore.kernel.org/r/20231226130745.465988-1-qde@naccy.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Add support to display uprobe_multi links 2023-11-29T05:50:09+00:00 Jiri Olsa jolsa@kernel.org 2023-11-25T19:31:30+00:00 a7795698f8b6c48283fa4334eb313bc1350b2864 Adding support to display details for uprobe_multi links, both plain: # bpftool link -p ... 24: uprobe_multi prog 126 uprobe.multi path /home/jolsa/bpf/test_progs func_cnt 3 pid 4143 offset ref_ctr_offset cookies 0xd1f88 0xf5d5a8 0xdead 0xd1f8f 0xf5d5aa 0xbeef 0xd1f96 0xf5d5ac 0xcafe and json: # bpftool link -p [{ ... },{ "id": 24, "type": "uprobe_multi", "prog_id": 126, "retprobe": false, "path": "/home/jolsa/bpf/test_progs", "func_cnt": 3, "pid": 4143, "funcs": [{ "offset": 860040, "ref_ctr_offset": 16111016, "cookie": 57005 },{ "offset": 860047, "ref_ctr_offset": 16111018, "cookie": 48879 },{ "offset": 860054, "ref_ctr_offset": 16111020, "cookie": 51966 } ] } ] Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20231125193130.834322-7-jolsa@kernel.org 
Adding support to display details for uprobe_multi links,
both plain:

  # bpftool link -p
  ...
  24: uprobe_multi  prog 126
          uprobe.multi  path /home/jolsa/bpf/test_progs  func_cnt 3  pid 4143
          offset             ref_ctr_offset     cookies
          0xd1f88            0xf5d5a8           0xdead
          0xd1f8f            0xf5d5aa           0xbeef
          0xd1f96            0xf5d5ac           0xcafe

and json:

  # bpftool link -p
  [{
  ...
      },{
          "id": 24,
          "type": "uprobe_multi",
          "prog_id": 126,
          "retprobe": false,
          "path": "/home/jolsa/bpf/test_progs",
          "func_cnt": 3,
          "pid": 4143,
          "funcs": [{
                  "offset": 860040,
                  "ref_ctr_offset": 16111016,
                  "cookie": 57005
              },{
                  "offset": 860047,
                  "ref_ctr_offset": 16111018,
                  "cookie": 48879
              },{
                  "offset": 860054,
                  "ref_ctr_offset": 16111020,
                  "cookie": 51966
              }
          ]
      }
  ]

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20231125193130.834322-7-jolsa@kernel.org
bpftool: mark orphaned programs during prog show 2023-11-28T00:23:38+00:00 Stanislav Fomichev sdf@google.com 2023-11-27T18:20:56+00:00 876843ce1e4897e8ceade50bfa3d9a4ec483abf3 Commit ef01f4e25c17 ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD") stopped removing program's id from idr when the offloaded/bound netdev goes away. I was supposed to take a look and check in [0], but apparently I did not. Martin points out it might be useful to keep it that way for observability sake, but we at least need to mark those programs as unusable. Mark those programs as 'orphaned' and keep printing the list when we encounter ENODEV. 0: unspec tag 0000000000000000 xlated 0B not jited memlock 4096B orphaned [0]: https://lore.kernel.org/all/CAKH8qBtyR20ZWAc11z1-6pGb3Hd47AQUTbE_cfoktG59TqaJ7Q@mail.gmail.com/ v3: * use two spaces for " orphaned" (Quentin) Cc: netdev@vger.kernel.org Fixes: ef01f4e25c17 ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD") Signed-off-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/r/20231127182057.1081138-1-sdf@google.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
Commit ef01f4e25c17 ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD
and PERF_BPF_EVENT_PROG_UNLOAD") stopped removing program's id from
idr when the offloaded/bound netdev goes away. I was supposed to
take a look and check in [0], but apparently I did not.

Martin points out it might be useful to keep it that way for
observability sake, but we at least need to mark those programs as
unusable.

Mark those programs as 'orphaned' and keep printing the list when
we encounter ENODEV.

0: unspec  tag 0000000000000000
        xlated 0B  not jited  memlock 4096B  orphaned

[0]: https://lore.kernel.org/all/CAKH8qBtyR20ZWAc11z1-6pGb3Hd47AQUTbE_cfoktG59TqaJ7Q@mail.gmail.com/

v3:
* use two spaces for "  orphaned" (Quentin)

Cc: netdev@vger.kernel.org
Fixes: ef01f4e25c17 ("bpf: restore the ebpf program ID for BPF_AUDIT_UNLOAD and PERF_BPF_EVENT_PROG_UNLOAD")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20231127182057.1081138-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
bpftool: Fix prog object type in manpage 2023-11-10T03:07:38+00:00 Artem Savkov asavkov@redhat.com 2023-11-03T08:11:26+00:00 a46afaa03f6db8c65492302ffdafcb2e769e5667 bpftool's man page lists "program" as one of possible values for OBJECT, while in fact bpftool accepts "prog" instead. Reported-by: Jerry Snitselaar <jsnitsel@redhat.com> Signed-off-by: Artem Savkov <asavkov@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20231103081126.170034-1-asavkov@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
bpftool's man page lists "program" as one of possible values for OBJECT,
while in fact bpftool accepts "prog" instead.

Reported-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20231103081126.170034-1-asavkov@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpftool: Extend net dump with netkit progs 2023-10-24T23:07:32+00:00 Daniel Borkmann daniel@iogearbox.net 2023-10-24T21:49:02+00:00 bec981a4add6dd6a63065e54e2b2e67c2af6c3fa Add support to dump BPF programs on netkit via bpftool. This includes both the BPF link and attach ops programs. Dumped information contain the attach location, function entry name, program ID and link ID when applicable. Example with tc BPF link: # ./bpftool net xdp: tc: nk1(22) netkit/peer tc1 prog_id 43 link_id 12 [...] Example with json dump: # ./bpftool net --json | jq [ { "xdp": [], "tc": [ { "devname": "nk1", "ifindex": 18, "kind": "netkit/primary", "name": "tc1", "prog_id": 29, "prog_flags": [], "link_id": 8, "link_flags": [] } ], "flow_dissector": [], "netfilter": [] } ] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20231024214904.29825-6-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
Add support to dump BPF programs on netkit via bpftool. This includes both
the BPF link and attach ops programs. Dumped information contain the attach
location, function entry name, program ID and link ID when applicable.

Example with tc BPF link:

  # ./bpftool net
  xdp:

  tc:
  nk1(22) netkit/peer tc1 prog_id 43 link_id 12

  [...]

Example with json dump:

  # ./bpftool net --json | jq
  [
    {
      "xdp": [],
      "tc": [
        {
          "devname": "nk1",
          "ifindex": 18,
          "kind": "netkit/primary",
          "name": "tc1",
          "prog_id": 29,
          "prog_flags": [],
          "link_id": 8,
          "link_flags": []
        }
      ],
      "flow_dissector": [],
      "netfilter": []
    }
  ]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231024214904.29825-6-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
bpftool: Implement link show support for netkit 2023-10-24T23:07:24+00:00 Daniel Borkmann daniel@iogearbox.net 2023-10-24T21:49:01+00:00 92a85e18ad4705c66ace55a19f4f8301ef0eb59f Add support to dump netkit link information to bpftool in similar way as we have for XDP. The netkit link info only exposes the ifindex and the attach_type. Below shows an example link dump output, and a cgroup link is included for comparison, too: # bpftool link [...] 10: cgroup prog 2466 cgroup_id 1 attach_type cgroup_inet6_post_bind [...] 8: netkit prog 35 ifindex nk1(18) attach_type netkit_primary [...] Equivalent json output: # bpftool link --json [...] { "id": 10, "type": "cgroup", "prog_id": 2466, "cgroup_id": 1, "attach_type": "cgroup_inet6_post_bind" }, [...] { "id": 12, "type": "netkit", "prog_id": 61, "devname": "nk1", "ifindex": 21, "attach_type": "netkit_primary" } [...] Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20231024214904.29825-5-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> 
Add support to dump netkit link information to bpftool in similar way as
we have for XDP. The netkit link info only exposes the ifindex and the
attach_type.

Below shows an example link dump output, and a cgroup link is included for
comparison, too:

  # bpftool link
  [...]
  10: cgroup  prog 2466
        cgroup_id 1  attach_type cgroup_inet6_post_bind
  [...]
  8: netkit  prog 35
        ifindex nk1(18)  attach_type netkit_primary
  [...]

Equivalent json output:

  # bpftool link --json
  [...]
  {
    "id": 10,
    "type": "cgroup",
    "prog_id": 2466,
    "cgroup_id": 1,
    "attach_type": "cgroup_inet6_post_bind"
  },
  [...]
  {
    "id": 12,
    "type": "netkit",
    "prog_id": 61,
    "devname": "nk1",
    "ifindex": 21,
    "attach_type": "netkit_primary"
  }
  [...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231024214904.29825-5-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>