Introduce bpf_ct_set_nat_info kfunc helper

Introduce bpf_ct_set_nat_info kfunc helper in order to set source and destination nat addresses/ports in a new allocated ct entry not inserted in the connection tracking table yet.
Introduce support for per-parameter trusted args.

Changes since v2:
- use int instead of a pointer for port in bpf_ct_set_nat_info signature
- modify KF_TRUSTED_ARGS definition in order to referenced pointer constraint just for PTR_TO_BTF_ID
- drop patch 2/4

Changes since v1:
- enable CONFIG_NF_NAT in tools/testing/selftests/bpf/config

Kumar Kartikeya Dwivedi (1):
bpf: Tweak definition of KF_TRUSTED_ARGS

Lorenzo Bianconi (2):
net: netfilter: add bpf_ct_set_nat_info kfunc helper selftests/bpf: add tests for bpf_ct_set_nat_info kfunc

 Documentation/bpf/kfuncs.rst                  | 24 ++++++----
 kernel/bpf/btf.c                              | 18 +++++--
 net/netfilter/nf_conntrack_bpf.c              | 47 ++++++++++++++++++-
 tools/testing/selftests/bpf/config            |  1 +
 .../testing/selftests/bpf/prog_tests/bpf_nf.c | 10 ++--
 .../testing/selftests/bpf/progs/test_bpf_nf.c | 27 +++++++++++
 6 files changed, 110 insertions(+), 17 deletions(-)

2.37.3