On 02/07/2018 01:40 PM, Jesper Dangaard Brouer wrote:
> On Tue, 6 Feb 2018 20:05:43 +0100 Daniel Borkmann <[email protected]>
> wrote:
>> On 02/06/2018 06:03 PM, Jesper Dangaard Brouer wrote:
> [...]
>>> [...] I plan to follow up and do a more complete solution later. This
>>> is a workaround to get the Suricata use-case working and also that
>>> samples/bpf/ can be loaded.
>>
>> Aside from a needed fix in any case, is there a specifc reason why Suricata
>> cannot rely on 'clang -target bpf'? Is it asm inline headers in your case?
>
> Below is the error I get when using 'clang' with '-target bpf'
>
> $ dirs
> ~/git/suricata/src/ebpf
>
> $ clang -Wall -Iinclude -O2 -D__KERNEL__ -target bpf -emit-llvm -c
> xdp_filter.c -o - | llc -march=bpf -filetype=obj -o xdp_filter.bpf
> In file included from xdp_filter.c:19:
> In file included from /usr/bin/../lib64/clang/4.0.1/include/stdint.h:63:
> In file included from /usr/include/stdint.h:26:
> In file included from /usr/include/bits/libc-header-start.h:33:
> In file included from /usr/include/features.h:434:
> /usr/include/gnu/stubs.h:7:11: fatal error: 'gnu/stubs-32.h' file not found
> # include <gnu/stubs-32.h>
> ^~~~~~~~~~~~~~~~
>
> I'll leave it up to Eric Leblond to figure out that he need to change
> in the eBPF programs to make it compile with '-target bpf'. Maybe you
> can offer him some guidance here?
>
> Direct link to code:
> https://github.com/OISF/suricata/blob/master/ebpf/xdp_filter.c
Sure, you just need glibc-devel.i686, see:
$ clang -Wall -Iinclude -O2 -D__KERNEL__ -target bpf -emit-llvm -c xdp_filter.c
-o - | llc -march=bpf -filetype=obj -o xdp_filter.bpf
In file included from xdp_filter.c:19:
In file included from
/home/darkstar/llvm/build/lib/clang/7.0.0/include/stdint.h:63:
In file included from /usr/include/stdint.h:25:
In file included from /usr/include/features.h:392:
/usr/include/gnu/stubs.h:7:11: fatal error: 'gnu/stubs-32.h' file not found
# include <gnu/stubs-32.h>
^~~~~~~~~~~~~~~~
1 error generated.
# yum install glibc-devel.i686
[...]
$ clang -Wall -Iinclude -O2 -D__KERNEL__ -target bpf -emit-llvm -c xdp_filter.c
-o - | llc -march=bpf -filetype=obj -o xdp_filter.bpf
$
Alternatively, you could do something like done in selftests to provide a
dummy, see commit 1c2dd16add7e ("selftests/bpf: get rid of -D__x86_64__").
Cheers,
Daniel
