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Date:   Mon, 11 Dec 2023 15:31:29 -0700
From:   Daniel Xu <dxu@dxuuu.xyz>
To:     Eyal Birger <eyal.birger@gmail.com>
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
Subject: Re: [PATCH bpf-next v5 9/9] bpf: xfrm: Add selftest for
 bpf_xdp_get_xfrm_state()
Message-ID: <7yjkfhrwdphtcljq3odv4jc6lucd32wcg277hfsf4ve2jbo7hp@vuqzwbq5nxjw>
References: <cover.1702325874.git.dxu@dxuuu.xyz>
 <8ec1b885d2e13fcd20944cce9edc0340d993d044.1702325874.git.dxu@dxuuu.xyz>
 <CAHsH6GsdqBN638uqUm+8QkP1_45coucSTL7o=D2wFW-gYjPaBw@mail.gmail.com>
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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 PM Daniel Xu <dxu@dxuuu.xyz> wrote:
> >
> > This commit extends test_tunnel selftest to test the new XDP xfrm state
> > 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/tools/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 = BPF_TC_INGRESS);
> > +       LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
> >         struct test_tunnel_kern *skel = 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 = bpf_program__fd(skel->progs.xfrm_get_state_xdp);
> > +       if (!ASSERT_GE(xdp_prog_fd, 0, "bpf_program__fd"))
> > +               goto done;
> > +       err = bpf_xdp_attach(ifindex, xdp_prog_fd, XDP_FLAGS_REPLACE, &opts);
> > +       if (!ASSERT_OK(err, "bpf_xdp_attach"))
> > +               goto done;
> > +
> >         /* ping from at_ns0 namespace test */
> >         nstoken = open_netns("at_ns0");
> >         err = 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_window"))
> > +               goto done;
> >
> >  done:
> >         delete_xfrm_tunnel();
> > diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/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_ctx,
> >                           struct bpf_fou_encap *encap, int type) __ksym;
> >  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_opts *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 = 0;
> > +
> > +SEC("xdp")
> > +int xfrm_get_state_xdp(struct xdp_md *xdp)
> > +{
> > +       struct bpf_xfrm_state_opts opts = {};
> > +       struct xfrm_state *x = NULL;
> > +       struct ip_esp_hdr *esph;
> > +       struct bpf_dynptr ptr;
> > +       u8 esph_buf[8] = {};
> > +       u8 iph_buf[20] = {};
> > +       struct iphdr *iph;
> > +       u32 off;
> > +
> > +       if (bpf_dynptr_from_xdp(xdp, 0, &ptr))
> > +               goto out;
> > +
> > +       off = sizeof(struct ethhdr);
> > +       iph = bpf_dynptr_slice(&ptr, off, iph_buf, sizeof(iph_buf));
> > +       if (!iph || iph->protocol != IPPROTO_ESP)
> > +               goto out;
> > +
> > +       off += sizeof(struct iphdr);
> > +       esph = bpf_dynptr_slice(&ptr, off, esph_buf, sizeof(esph_buf));
> > +       if (!esph)
> > +               goto out;
> > +
> > +       opts.netns_id = BPF_F_CURRENT_NETNS;
> > +       opts.daddr.a4 = iph->daddr;
> > +       opts.spi = esph->spi;
> > +       opts.proto = IPPROTO_ESP;
> > +       opts.family = AF_INET;
> > +
> > +       x = bpf_xdp_get_xfrm_state(xdp, &opts, sizeof(opts));
> > +       if (!x || opts.error)
> 
> nit: how can opts.error be non zero if x == NULL?

Ignoring the new -ENOENT case, it can't. Which is why I'm testing that
behavior here.

[...]

Thanks,
Daniel