bpf: xfrm: Add selftest for bpf_xdp_get_xfrm_state()

This commit extends test_tunnel selftest to test the new XDP xfrm state
lookup kfunc.

Co-developed-by: Antony Antony <[email protected]>
Signed-off-by: Antony Antony <[email protected]>
Signed-off-by: Daniel Xu <[email protected]>
Link: https://lore.kernel.org/r/e704e9a4332e3eac7b458e4bfdec8fcc6984cdb6.1702593901.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: danobi

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,
@@ -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,
@@ -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();

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)
+		goto out;
+
+	if (!x->replay_esn)
+		goto out;
+
+	xfrm_replay_window = x->replay_esn->replay_window;
+out:
+	if (x)
+		bpf_xdp_xfrm_state_release(x);
+	return XDP_PASS;
+}
+
 char _license[] SEC("license") = "GPL";