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From:   Eyal Birger <eyal.birger@gmail.com>
Date:   Mon, 11 Dec 2023 15:13:07 -0800
Message-ID: <CAHsH6Gs1vUQnhR_a4qFnAF37Vx=68Do28sfVfFxQ9pVj9jSzjw@mail.gmail.com>
Subject: Re: [PATCH bpf-next v5 9/9] bpf: xfrm: Add selftest for bpf_xdp_get_xfrm_state()
To:     Daniel Xu <dxu@dxuuu.xyz>
Cc:     daniel@iogearbox.net, davem@davemloft.net, shuah@kernel.org,
        ast@kernel.org, john.fastabend@gmail.com, kuba@kernel.org,
        andrii@kernel.org, hawk@kernel.org, steffen.klassert@secunet.com,
        antony.antony@secunet.com, alexei.starovoitov@gmail.com,
        yonghong.song@linux.dev, eddyz87@gmail.com, mykolal@fb.com,
        martin.lau@linux.dev, song@kernel.org, kpsingh@kernel.org,
        sdf@google.com, haoluo@google.com, jolsa@kernel.org,
        bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        devel@linux-ipsec.org
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On Mon, Dec 11, 2023 at 2:31=E2=80=AFPM Daniel Xu <dxu@dxuuu.xyz> wrote:
>
> On Mon, Dec 11, 2023 at 01:39:25PM -0800, Eyal Birger wrote:
> > Hi Daniel,
> >
> > Tiny nits below in case you respin this for other reasons:
> >
> > On Mon, Dec 11, 2023 at 12:20=E2=80=AFPM Daniel Xu <dxu@dxuuu.xyz> wrot=
e:
> > >
> > > This commit extends test_tunnel selftest to test the new XDP xfrm sta=
te
> > > lookup kfunc.
> > >
> > > Co-developed-by: Antony Antony <antony.antony@secunet.com>
> > > Signed-off-by: Antony Antony <antony.antony@secunet.com>
> > > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
> > > ---
> > >  .../selftests/bpf/prog_tests/test_tunnel.c    | 20 ++++++--
> > >  .../selftests/bpf/progs/test_tunnel_kern.c    | 51 +++++++++++++++++=
++
> > >  2 files changed, 67 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/test_tunnel.c b/t=
ools/testing/selftests/bpf/prog_tests/test_tunnel.c
> > > index 2d7f8fa82ebd..fc804095d578 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/test_tunnel.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/test_tunnel.c
> > > @@ -278,7 +278,7 @@ static int add_xfrm_tunnel(void)
> > >         SYS(fail,
> > >             "ip netns exec at_ns0 "
> > >                 "ip xfrm state add src %s dst %s proto esp "
> > > -                       "spi %d reqid 1 mode tunnel "
> > > +                       "spi %d reqid 1 mode tunnel replay-window 42 =
"
> > >                         "auth-trunc 'hmac(sha1)' %s 96 enc 'cbc(aes)'=
 %s",
> > >             IP4_ADDR_VETH0, IP4_ADDR1_VETH1, XFRM_SPI_IN_TO_OUT, XFRM=
_AUTH, XFRM_ENC);
> > >         SYS(fail,
> > > @@ -292,7 +292,7 @@ static int add_xfrm_tunnel(void)
> > >         SYS(fail,
> > >             "ip netns exec at_ns0 "
> > >                 "ip xfrm state add src %s dst %s proto esp "
> > > -                       "spi %d reqid 2 mode tunnel "
> > > +                       "spi %d reqid 2 mode tunnel replay-window 42 =
"
> >
> > nit: why do you need to set the replay-window in both directions?
>
> No reason - probably just careless here.
>
> >
> > >                         "auth-trunc 'hmac(sha1)' %s 96 enc 'cbc(aes)'=
 %s",
> > >             IP4_ADDR1_VETH1, IP4_ADDR_VETH0, XFRM_SPI_OUT_TO_IN, XFRM=
_AUTH, XFRM_ENC);
> > >         SYS(fail,
> > > @@ -313,7 +313,7 @@ static int add_xfrm_tunnel(void)
> > >          */
> > >         SYS(fail,
> > >             "ip xfrm state add src %s dst %s proto esp "
> > > -                   "spi %d reqid 1 mode tunnel "
> > > +                   "spi %d reqid 1 mode tunnel replay-window 42 "
> > >                     "auth-trunc 'hmac(sha1)' %s 96  enc 'cbc(aes)' %s=
",
> > >             IP4_ADDR_VETH0, IP4_ADDR1_VETH1, XFRM_SPI_IN_TO_OUT, XFRM=
_AUTH, XFRM_ENC);
> > >         SYS(fail,
> > > @@ -325,7 +325,7 @@ static int add_xfrm_tunnel(void)
> > >         /* root -> at_ns0 */
> > >         SYS(fail,
> > >             "ip xfrm state add src %s dst %s proto esp "
> > > -                   "spi %d reqid 2 mode tunnel "
> > > +                   "spi %d reqid 2 mode tunnel replay-window 42 "
> > >                     "auth-trunc 'hmac(sha1)' %s 96  enc 'cbc(aes)' %s=
",
> > >             IP4_ADDR1_VETH1, IP4_ADDR_VETH0, XFRM_SPI_OUT_TO_IN, XFRM=
_AUTH, XFRM_ENC);
> > >         SYS(fail,
> > > @@ -628,8 +628,10 @@ static void test_xfrm_tunnel(void)
> > >  {
> > >         DECLARE_LIBBPF_OPTS(bpf_tc_hook, tc_hook,
> > >                             .attach_point =3D BPF_TC_INGRESS);
> > > +       LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
> > >         struct test_tunnel_kern *skel =3D NULL;
> > >         struct nstoken *nstoken;
> > > +       int xdp_prog_fd;
> > >         int tc_prog_fd;
> > >         int ifindex;
> > >         int err;
> > > @@ -654,6 +656,14 @@ static void test_xfrm_tunnel(void)
> > >         if (attach_tc_prog(&tc_hook, tc_prog_fd, -1))
> > >                 goto done;
> > >
> > > +       /* attach xdp prog to tunnel dev */
> > > +       xdp_prog_fd =3D bpf_program__fd(skel->progs.xfrm_get_state_xd=
p);
> > > +       if (!ASSERT_GE(xdp_prog_fd, 0, "bpf_program__fd"))
> > > +               goto done;
> > > +       err =3D bpf_xdp_attach(ifindex, xdp_prog_fd, XDP_FLAGS_REPLAC=
E, &opts);
> > > +       if (!ASSERT_OK(err, "bpf_xdp_attach"))
> > > +               goto done;
> > > +
> > >         /* ping from at_ns0 namespace test */
> > >         nstoken =3D open_netns("at_ns0");
> > >         err =3D test_ping(AF_INET, IP4_ADDR_TUNL_DEV1);
> > > @@ -667,6 +677,8 @@ static void test_xfrm_tunnel(void)
> > >                 goto done;
> > >         if (!ASSERT_EQ(skel->bss->xfrm_remote_ip, 0xac100164, "remote=
_ip"))
> > >                 goto done;
> > > +       if (!ASSERT_EQ(skel->bss->xfrm_replay_window, 42, "replay_win=
dow"))
> > > +               goto done;
> > >
> > >  done:
> > >         delete_xfrm_tunnel();
> > > diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/t=
ools/testing/selftests/bpf/progs/test_tunnel_kern.c
> > > index 3a59eb9c34de..c0dd38616562 100644
> > > --- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
> > > +++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
> > > @@ -30,6 +30,10 @@ int bpf_skb_set_fou_encap(struct __sk_buff *skb_ct=
x,
> > >                           struct bpf_fou_encap *encap, int type) __ks=
ym;
> > >  int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
> > >                           struct bpf_fou_encap *encap) __ksym;
> > > +struct xfrm_state *
> > > +bpf_xdp_get_xfrm_state(struct xdp_md *ctx, struct bpf_xfrm_state_opt=
s *opts,
> > > +                      u32 opts__sz) __ksym;
> > > +void bpf_xdp_xfrm_state_release(struct xfrm_state *x) __ksym;
> > >
> > >  struct {
> > >         __uint(type, BPF_MAP_TYPE_ARRAY);
> > > @@ -950,4 +954,51 @@ int xfrm_get_state(struct __sk_buff *skb)
> > >         return TC_ACT_OK;
> > >  }
> > >
> > > +volatile int xfrm_replay_window =3D 0;
> > > +
> > > +SEC("xdp")
> > > +int xfrm_get_state_xdp(struct xdp_md *xdp)
> > > +{
> > > +       struct bpf_xfrm_state_opts opts =3D {};
> > > +       struct xfrm_state *x =3D NULL;
> > > +       struct ip_esp_hdr *esph;
> > > +       struct bpf_dynptr ptr;
> > > +       u8 esph_buf[8] =3D {};
> > > +       u8 iph_buf[20] =3D {};
> > > +       struct iphdr *iph;
> > > +       u32 off;
> > > +
> > > +       if (bpf_dynptr_from_xdp(xdp, 0, &ptr))
> > > +               goto out;
> > > +
> > > +       off =3D sizeof(struct ethhdr);
> > > +       iph =3D bpf_dynptr_slice(&ptr, off, iph_buf, sizeof(iph_buf))=
;
> > > +       if (!iph || iph->protocol !=3D IPPROTO_ESP)
> > > +               goto out;
> > > +
> > > +       off +=3D sizeof(struct iphdr);
> > > +       esph =3D bpf_dynptr_slice(&ptr, off, esph_buf, sizeof(esph_bu=
f));
> > > +       if (!esph)
> > > +               goto out;
> > > +
> > > +       opts.netns_id =3D BPF_F_CURRENT_NETNS;
> > > +       opts.daddr.a4 =3D iph->daddr;
> > > +       opts.spi =3D esph->spi;
> > > +       opts.proto =3D IPPROTO_ESP;
> > > +       opts.family =3D AF_INET;
> > > +
> > > +       x =3D bpf_xdp_get_xfrm_state(xdp, &opts, sizeof(opts));
> > > +       if (!x || opts.error)
> >
> > nit: how can opts.error be non zero if x =3D=3D NULL?
>
> Ignoring the new -ENOENT case, it can't. Which is why I'm testing that
> behavior here.

I'm sorry, I don't understand.

AFAICT, regardless of the -ENOENT change, I don't see
how (!x) is false and (opt.error) is true, and so
"if (!x || opts.error)" is always equivalent to "if (!x)".

What am I missing?
Eyal.