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Subject: Re: [PATCH bpf-next] selftests/bpf: Fix undeclared identifier build
 errors of test_bpf_nf.c
To:     Yonghong Song <yhs@meta.com>,
        Alan Maguire <alan.maguire@oracle.com>,
        Eduard Zingerman <eddyz87@gmail.com>,
        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>
References: <1673844908-11533-1-git-send-email-yangtiezhu@loongson.cn>
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 <556dc633-e7fb-da8a-1fa9-757684edd3a4@oracle.com>
 <dffe5523-4ff7-8b27-46fa-079a9556166f@meta.com>
Cc:     bpf@vger.kernel.org, linux-kernel@vger.kernel.org
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <d299be28-42f5-b387-5b54-74694ff5f340@loongson.cn>
Date:   Tue, 17 Jan 2023 17:52:36 +0800
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On 01/17/2023 02:48 PM, Yonghong Song wrote:
>
>
> On 1/16/23 5:54 AM, Alan Maguire wrote:
>> On 16/01/2023 12:30, Eduard Zingerman wrote:
>>> On Mon, 2023-01-16 at 12:55 +0800, Tiezhu Yang wrote:
>>>> $ 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
>>>> to fix the above build errors.
>>>>
>>>> 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 | 5 +++++
>>>>   1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/tools/testing/selftests/bpf/progs/test_bpf_nf.c
>>>> b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
>>>> index 227e85e..114f961 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 {
>>>> +    NF_NAT_MANIP_SRC,
>>>> +    NF_NAT_MANIP_DST
>>>> +};
>>>> +
>>>
>>> This is confusing, when I build the kernel/tests I get the declaration
>>> the "enum nf_nat_manip_type" from the vmlinux.h (which is included
>>> from test_bpf_nf.c).
>>> Which means that this patch results in compilation error with my
>>> configuration.
>>> Is there a chance that your kernel is configured without some
>>> necessary netfilter
>>> configuration options? Have you tried this patch with BPF CI?
>>>
>>
>> Yep; I suspect if CONFIG_NF_NAT=m , the required definitions won't
>> make it
>> into vmlinux.h. The reference tools/testing/seftests/bpf/config has
>> CONFIG_NF_NAT=y so it is at least documented in the referenced config.
>>
>> I'd suggest going the route of
>>
>> commit aa67961f3243dfff26c47769f87b4d94b07ec71f
>> Author: Martin KaFai Lau <martin.lau@kernel.org>
>> Date:   Tue Dec 6 11:35:54 2022 -0800
>>
>>      selftests/bpf: Allow building bpf tests with
>> CONFIG_XFRM_INTERFACE=[m|n]
>>      ...and adding/using local definitons like:
>>
>> enum nf_nat_manip_type_local {
>>     NF_NAT_MANIP_SRC_LOCAL,
>>     NF_NAT_MANIP_DST_LOCAL
>> };
>
> The above won't support core, and since preserve_access_index attribute
> does not support enum for now. We need to use bpf_core_enum_value to
> retrieve the proper value through CORE.
>
> could you try the following?
>
> enum nf_nat_manip_type___local {
>     NF_NAT_MANIP_SRC___LOCAL,
>     NF_NAT_MANIP_DST___LOCAL,
> };

This is OK, it is similar with commit 1058b6a78db2 ("selftests/bpf: Do 
not fail build if CONFIG_NF_CONNTRACK=m/n").

>
> ...
> bpf_ct_set_nat_info(ct, &saddr, sport, bpf_core_enum_value(enum
> nf_nat_manip_type___local,  NF_NAT_MANIP_SRC___LOCAL));
> ...
>
> bpf_ct_set_nat_info(ct, &daddr, dport, bpf_core_enum_value(enum
> nf_nat_manip_type___local,  NF_NAT_MANIP_DST___LOCAL));
>
> whether it works or not? Could you also try if the
> enumerator sequence in enum nf_nat_manip_type___local changed?
>
>>
>> ...to avoid the name clash.
>>
>>
>> Alan

I tested this on x86_64 fedora 36, using config-5.17.5-300.fc36.x86_64
to generate .config, CONFIG_NF_CONNTRACK=m, CONFIG_NF_NAT=m, there are
no definitions of NF_NAT_MANIP_SRC and NF_NAT_MANIP_DST in vmlinux.h,
build test_bpf_nf.c failed.

$ grep -w CONFIG_NF_CONNTRACK /boot/config-5.17.5-300.fc36.x86_64
CONFIG_NF_CONNTRACK=m
$ grep -w CONFIG_NF_NAT /boot/config-5.17.5-300.fc36.x86_64
CONFIG_NF_NAT=m

I tested with various configs, the definitions of NF_NAT_MANIP_SRC and
NF_NAT_MANIP_DST in vmlinux.h only depend on CONFIG_NF_CONNTRACK=y.

(1) CONFIG_NF_CONNTRACK=m, CONFIG_NF_NAT=m, no definitions
$ grep -w CONFIG_NF_CONNTRACK .config
CONFIG_NF_CONNTRACK=m
$ grep -w CONFIG_NF_NAT .config
CONFIG_NF_NAT=m
$ grep NF_NAT_MANIP_SRC tools/testing/selftests/bpf/tools/include/vmlinux.h
$ grep NF_NAT_MANIP_DST tools/testing/selftests/bpf/tools/include/vmlinux.h
$

(2) CONFIG_NF_CONNTRACK=m, CONFIG_NF_NAT=y, no definitions
This case is unable, because CONFIG_NF_NAT depends on CONFIG_NF_CONNTRACK.

(3) CONFIG_NF_CONNTRACK=m, CONFIG_NF_NAT=n, no definitions
$ grep -w CONFIG_NF_CONNTRACK .config
CONFIG_NF_CONNTRACK=m
$ grep -w CONFIG_NF_NAT .config
# CONFIG_NF_NAT is not set
$ grep NF_NAT_MANIP_SRC tools/testing/selftests/bpf/tools/include/vmlinux.h
$ grep NF_NAT_MANIP_DST tools/testing/selftests/bpf/tools/include/vmlinux.h
$

(4) CONFIG_NF_CONNTRACK=y, CONFIG_NF_NAT=m, have definitions
$ grep -w CONFIG_NF_CONNTRACK .config
CONFIG_NF_CONNTRACK=y
$ grep -w CONFIG_NF_NAT .config
CONFIG_NF_NAT=m
$ grep NF_NAT_MANIP_SRC tools/testing/selftests/bpf/tools/include/vmlinux.h
	NF_NAT_MANIP_SRC = 0,
$ grep NF_NAT_MANIP_DST tools/testing/selftests/bpf/tools/include/vmlinux.h
	NF_NAT_MANIP_DST = 1,

(5) CONFIG_NF_CONNTRACK=y, CONFIG_NF_NAT=y, have definitions
$ grep -w CONFIG_NF_CONNTRACK .config
CONFIG_NF_CONNTRACK=y
$ grep -w CONFIG_NF_NAT .config
CONFIG_NF_NAT=y
$ grep NF_NAT_MANIP_SRC tools/testing/selftests/bpf/tools/include/vmlinux.h
	NF_NAT_MANIP_SRC = 0,
$ grep NF_NAT_MANIP_DST tools/testing/selftests/bpf/tools/include/vmlinux.h
	NF_NAT_MANIP_DST = 1,

(6) CONFIG_NF_CONNTRACK=y, CONFIG_NF_NAT=n, have definitions
$ grep -w CONFIG_NF_CONNTRACK .config
CONFIG_NF_CONNTRACK=y
$ grep -w CONFIG_NF_NAT .config
# CONFIG_NF_NAT is not set
$ grep NF_NAT_MANIP_SRC tools/testing/selftests/bpf/tools/include/vmlinux.h
	NF_NAT_MANIP_SRC = 0,
$ grep NF_NAT_MANIP_DST tools/testing/selftests/bpf/tools/include/vmlinux.h
	NF_NAT_MANIP_DST = 1,

(7) CONFIG_NF_CONNTRACK=n, CONFIG_NF_NAT=n, no definitions
$ grep -w CONFIG_NF_CONNTRACK .config
# CONFIG_NF_CONNTRACK is not set
$ grep -w CONFIG_NF_NAT .config
$ grep NF_NAT_MANIP_SRC tools/testing/selftests/bpf/tools/include/vmlinux.h
$ grep NF_NAT_MANIP_DST tools/testing/selftests/bpf/tools/include/vmlinux.h
$

(8) CONFIG_NF_CONNTRACK=n, CONFIG_NF_NAT=y, no definitions
This case is unable, because CONFIG_NF_NAT depends on CONFIG_NF_CONNTRACK.

Here is an alternative change to check whether CONFIG_NF_CONNTRACK
is m, enum nf_nat_manip_type___local is simple, which one is better?

$ git diff tools/testing/selftests/bpf/
diff --git a/tools/testing/selftests/bpf/Makefile 
b/tools/testing/selftests/bpf/Makefile
index 22533a18705e..f3cf02046c20 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -325,7 +325,7 @@ endif

  CLANG_SYS_INCLUDES = $(call 
get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH))
  BPF_CFLAGS = -g -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN)          \
-            -I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR)                   \
+            -I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR) -I$(TOOLSINCDIR)  \
              -I$(abspath $(OUTPUT)/../usr/include)

  CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
diff --git a/tools/testing/selftests/bpf/progs/test_bpf_nf.c 
b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
index 227e85e85dda..f2101807072f 100644
--- a/tools/testing/selftests/bpf/progs/test_bpf_nf.c
+++ b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
@@ -2,6 +2,7 @@
  #include <vmlinux.h>
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_endian.h>
+#include <linux/kconfig.h>

  #define EAFNOSUPPORT 97
  #define EPROTO 71
@@ -34,6 +35,13 @@ __be16 dport = 0;
  int test_exist_lookup = -ENOENT;
  u32 test_exist_lookup_mark = 0;

+#if IS_MODULE(CONFIG_NF_CONNTRACK)
+enum nf_nat_manip_type {
+       NF_NAT_MANIP_SRC,
+       NF_NAT_MANIP_DST
+};
+#endif
+
  struct nf_conn;

  struct bpf_ct_opts___local {

Note that when unset CONFIG_NF_CONNTRACK, there are much more
build errors, I do not know whether it is necessary to fix it
and how to fix it properly. Here, I only consider the failed
case CONFIG_NF_CONNTRACK=m.

Thanks,
Tiezhu