Re: [PATCH bpf-next v2] selftests/bpf: Fix build errors if CONFIG_NF_CONNTRACK=m

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Andrii Nakryiko <andrii@kernel.org>,
	Mykola Lysenko <mykolal@fb.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v2] selftests/bpf: Fix build errors if CONFIG_NF_CONNTRACK=m
Date: Mon, 23 Jan 2023 15:17:35 -0800	[thread overview]
Message-ID: <CAEf4BzZfBb75smH0uTn4E36T6vk1xhZZ+5_ONtdh9aFQCMH2pw@mail.gmail.com> (raw)
In-Reply-To: <1674028604-7113-1-git-send-email-yangtiezhu@loongson.cn>

On Tue, Jan 17, 2023 at 11:57 PM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> If CONFIG_NF_CONNTRACK=m, there are no definitions of NF_NAT_MANIP_SRC
> and NF_NAT_MANIP_DST in vmlinux.h, build test_bpf_nf.c failed.
>
> $ make -C tools/testing/selftests/bpf/
>
>   CLNG-BPF [test_maps] test_bpf_nf.bpf.o
> progs/test_bpf_nf.c:160:42: error: use of undeclared identifier 'NF_NAT_MANIP_SRC'
>                 bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC);
>                                                        ^
> progs/test_bpf_nf.c:163:42: error: use of undeclared identifier 'NF_NAT_MANIP_DST'
>                 bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST);
>                                                        ^
> 2 errors generated.
>
> Copy the definitions in include/net/netfilter/nf_nat.h to test_bpf_nf.c,
> in order to avoid redefinitions if CONFIG_NF_CONNTRACK=y, rename them with
> ___local suffix. This is similar with commit 1058b6a78db2 ("selftests/bpf:
> Do not fail build if CONFIG_NF_CONNTRACK=m/n").
>
> Fixes: b06b45e82b59 ("selftests/bpf: add tests for bpf_ct_set_nat_info kfunc")
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>  tools/testing/selftests/bpf/progs/test_bpf_nf.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/test_bpf_nf.c b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
> index 227e85e..9fc603c 100644
> --- a/tools/testing/selftests/bpf/progs/test_bpf_nf.c
> +++ b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
> @@ -34,6 +34,11 @@ __be16 dport = 0;
>  int test_exist_lookup = -ENOENT;
>  u32 test_exist_lookup_mark = 0;
>
> +enum nf_nat_manip_type___local {
> +       NF_NAT_MANIP_SRC___local,
> +       NF_NAT_MANIP_DST___local
> +};
> +
>  struct nf_conn;
>
>  struct bpf_ct_opts___local {
> @@ -58,7 +63,7 @@ int bpf_ct_change_timeout(struct nf_conn *, u32) __ksym;
>  int bpf_ct_set_status(struct nf_conn *, u32) __ksym;
>  int bpf_ct_change_status(struct nf_conn *, u32) __ksym;
>  int bpf_ct_set_nat_info(struct nf_conn *, union nf_inet_addr *,
> -                       int port, enum nf_nat_manip_type) __ksym;
> +                       int port, enum nf_nat_manip_type___local) __ksym;
>
>  static __always_inline void
>  nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
> @@ -157,10 +162,10 @@ nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
>
>                 /* snat */
>                 saddr.ip = bpf_get_prandom_u32();
> -               bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC);
> +               bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC___local);
>                 /* dnat */
>                 daddr.ip = bpf_get_prandom_u32();
> -               bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST);
> +               bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST___local);
>

it would be a bit more reliable if you used `bpf_core_enum_value(enum
nf_nat_manip_type___local, NF_NAT_MANIP_DST___local)`. That would make
libbpf substitute correct absolute value, if actual enum
nf_nat_manip_type in kernel ever changed. Please consider a follow up
patch for this.

>                 ct_ins = bpf_ct_insert_entry(ct);
>                 if (ct_ins) {
> --
> 2.1.0
>