Re: Cannot load eBPF program as XDP

[Daniel Borkmann <daniel@xxxxxxxxxxxxx>]

On 06/28/2017 04:32 AM, MD I. Islam wrote:
> On Tue, Jun 27, 2017 at 10:05 PM, Y Song <ys114321@xxxxxxxxx> wrote:
> > xdp meta data is different:
> >
> > struct xdp_md {
> >          __u32 data;
> >          __u32 data_end;
> > };
> >
> > All other fields available for skb metadata won't be available in XDP.
> > That is way
> > you get verification failure.
>
> Thanks for the quick reply! Now I'm trying xdp1_kern.c which uses
> xdp_md. Now I'm getting the error:
>
> Note: 8 bytes struct bpf_elf_map fixup performed due to size mismatch!

This one is harmless, just telling you that the native bpf_elf_map
from iproute2 is different than the one you're loading, so it fixes
up the remaining 8 bytes automatically.

> RTNETLINK answers: Operation not supported

This one seems likely that the driver you're trying to attach this to
does not have XDP support. What's the driver you're using?

> Could you please advise me what is wrong here?
>
> > On Tue, Jun 27, 2017 at 7:00 PM, MD I. Islam <tamim@xxxxxxxxxxx> wrote:
> > > Hi
> > >
> > > I'm using http://lingrok.org/xref/linux-net-next/samples/bpf/parse_simple.c.
> > >
> > > I can load the program as tc_cls using following commands:
> > >
> > > sudo tc qdisc add dev eno1 clsact
> > > sudo tc filter add dev eno1  ingress bpf da obj parse_simple.o sec simple
> > >
> > > But I get error when I load the same program in XDP:
> > >
> > > sudo ip link set dev eno1 xdp obj parse_simple.o section simple
> > >
> > > Prog section 'simple' rejected: Permission denied (13)!
> > >   - Type:         6
> > >   - Instructions: 23 (0 over limit)
> > >   - License:      GPL
> > >
> > > Verifier analysis:
> > >
> > > 0: (b7) r0 = 0
> > > 1: (61) r2 = *(u32 *)(r1 +80)
> > > invalid bpf_context access off=80 size=4
> > >
> > > Error fetching program/map!
> > >
> > > I made sure that the parse_simple.o have necessary permission. Could
> > > you please advise what is wrong here? I'm using Kernel 4.11+. Does XDP
> > > need any specific kernel configuration enabled? clang and LLVM
> > > versions are as following:
> > >
> > > clang --version
> > > clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final)
> > > Target: x86_64-pc-linux-gnu
> > >
> > > llc --version
> > > LLVM (http://llvm.org/):
> > >    LLVM version 3.8.0
> > >
> > >    Optimized build.
> > >    Built Jul  9 2016 (11:22:59).
> > >    Default target: x86_64-pc-linux-gnu
> > >    Host CPU: haswell
> > >
> > >    Registered Targets:
> > >      aarch64    - AArch64 (little endian)
> > >      aarch64_be - AArch64 (big endian)
> > >      amdgcn     - AMD GCN GPUs
> > >      arm        - ARM
> > >      arm64      - ARM64 (little endian)
> > >      armeb      - ARM (big endian)
> > >      bpf        - BPF (host endian)
> > >      bpfeb      - BPF (big endian)
> > >      bpfel      - BPF (little endian)
> > >      cpp        - C++ backend
> > >      hexagon    - Hexagon
> > >      mips       - Mips
> > >      mips64     - Mips64 [experimental]
> > >      mips64el   - Mips64el [experimental]
> > >      mipsel     - Mipsel
> > >      msp430     - MSP430 [experimental]
> > >      nvptx      - NVIDIA PTX 32-bit
> > >      nvptx64    - NVIDIA PTX 64-bit
> > >      ppc32      - PowerPC 32
> > >      ppc64      - PowerPC 64
> > >      ppc64le    - PowerPC 64 LE
> > >      r600       - AMD GPUs HD2XXX-HD6XXX
> > >      sparc      - Sparc
> > >      sparcel    - Sparc LE
> > >      sparcv9    - Sparc V9
> > >      systemz    - SystemZ
> > >      thumb      - Thumb
> > >      thumbeb    - Thumb (big endian)
> > >      x86        - 32-bit X86: Pentium-Pro and above
> > >      x86-64     - 64-bit X86: EM64T and AMD64
> > >      xcore      - XCore
> > >
> > > Many thanks
> > > Tamim
>
> Thanks
> Tamim