Re: [PATCH bpf-next] selftests/bpf: Fix undeclared identifier build errors of test_bpf_nf.c

[Yonghong Song <yhs@meta.com>]

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,
};

...
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