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

[Alan Maguire <alan.maguire@oracle.com>]

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
};

...to avoid the name clash.


Alan