Kprobe for nf_nat is broken in Latest Debian 6.1.66-1

[P K <pkopensrc@xxxxxxxxx>]

Hi,

In recent debian kernel 6.1.66-1 kprobe to nf_nat_ipv4_manip_pkt or
any nf_nat function is not working. It was working fine on 6.1.55-1
kfunc is working fine.

Any suggestions on how to fix this?

Below are logs:

Not working :

/ # bpftrace --info
System
  OS: Linux 6.1.0-15-cloud-amd64 #1 SMP PREEMPT_DYNAMIC Debian
6.1.66-1 (2023-12-09)
  Arch: x86_64

Build
  version: v0.17.1
  LLVM: 16.0.3
  unsafe uprobe: no
  bfd: yes
  libdw (DWARF support): yes

Kernel helpers
  probe_read: yes
  probe_read_str: yes
  probe_read_user: yes
  probe_read_user_str: yes
  probe_read_kernel: yes
  probe_read_kernel_str: yes
  get_current_cgroup_id: yes
  send_signal: yes
  override_return: no
  get_boot_ns: yes
  dpath: yes
  skboutput: no

Kernel features
  Instruction limit: 1000000
  Loop support: yes
  btf: yes
  map batch: yes
  uprobe refcount (depends on Build:bcc bpf_attach_uprobe refcount): yes

Map types
  hash: yes
  percpu hash: yes
  array: yes
  percpu array: yes
  stack_trace: yes
  perf_event_array: yes

Probe types
  kprobe: yes
  tracepoint: yes
  perf_event: yes
  kfunc: yes
  iter:task: yes
  iter:task_file: yes
  kprobe_multi: no
  raw_tp_special: yes

/ #

$ sudo bpftrace -l | grep "manip"
kfunc:nf_nat:l4proto_manip_pkt
kfunc:nf_nat:nf_nat_ipv4_manip_pkt
kfunc:nf_nat:nf_nat_ipv6_manip_pkt
kfunc:nf_nat:nf_nat_manip_pkt
kprobe:l4proto_manip_pkt
kprobe:nf_nat_ipv4_manip_pkt
kprobe:nf_nat_ipv6_manip_pkt
kprobe:nf_nat_manip_pkt


/ # bpftrace -e 'kprobe:nf_nat_ipv4_manip_pkt { printf("func called\n"); }'
Attaching 1 probe...
cannot attach kprobe, probe entry may not exist
ERROR: Error attaching probe: 'kprobe:nf_nat_ipv4_manip_pkt'


/ # bpftrace -e 'kfunc:nf_nat:nf_nat_ipv4_manip_pkt { printf("func
called\n"); }'
Attaching 1 probe...

func called
func called
func called
func called
func called
func called
func called
func called
func called
func called
func called
func called
^C

/ #


Working:
/ # bpftrace --info
System
  OS: Linux 6.1.0-13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.55-1 (2023-09-29)
  Arch: x86_64

Build
  version: v0.17.1
  LLVM: 16.0.3
  unsafe uprobe: no
  bfd: yes
  libdw (DWARF support): yes

Kernel helpers
  probe_read: yes
  probe_read_str: yes
  probe_read_user: yes
  probe_read_user_str: yes
  probe_read_kernel: yes
  probe_read_kernel_str: yes
  get_current_cgroup_id: yes
  send_signal: yes
  override_return: no
  get_boot_ns: yes
  dpath: yes
  skboutput: no

Kernel features
  Instruction limit: 1000000
  Loop support: yes
  btf: yes
  map batch: yes
  uprobe refcount (depends on Build:bcc bpf_attach_uprobe refcount): yes

Map types
  hash: yes
  percpu hash: yes
  array: yes
  percpu array: yes
  stack_trace: yes
  perf_event_array: yes

Probe types
  kprobe: yes
  tracepoint: yes
  perf_event: yes
  kfunc: yes
  iter:task: yes
  iter:task_file: yes
  kprobe_multi: no
  raw_tp_special: yes


/ # bpftrace -l | grep "manip"
kprobe:l4proto_manip_pkt
kprobe:nf_nat_ipv4_manip_pkt
kprobe:nf_nat_ipv6_manip_pkt
kprobe:nf_nat_manip_pkt
/ #


/ # bpftrace --version
bpftrace v0.17.1
/ # bpftrace -e 'kprobe:nf_nat_ipv4_manip_pkt { printf("func called\n"); }'
Attaching 1 probe...
func called
func called
func called
func called
func called
func called
func called
func called
^C

/ # bpftrace -e 'kfunc:nf_nat:nf_nat_ipv4_manip_pkt { printf("func
called\n"); }'
Attaching 1 probe...
func called
func called
func called
func called
func called
func called
func called
func called
func called

^C
/ #