selftests/bpf: add tests for bpf_ct_set_nat_info kfunc

Introduce self-tests for bpf_ct_set_nat_info kfunc used to set the
source or destination nat addresses/ports.

Signed-off-by: Lorenzo Bianconi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/testing/selftests/bpf/config

···
 CONFIG_NF_CONNTRACK_MARK=y
 CONFIG_NF_DEFRAG_IPV4=y
 CONFIG_NF_DEFRAG_IPV6=y
+CONFIG_NF_NAT=y
 CONFIG_RC_CORE=y
 CONFIG_SECURITY=y
 CONFIG_SECURITYFS=y

tools/testing/selftests/bpf/prog_tests/bpf_nf.c

···
 	TEST_TC_BPF,
 };
 
-#define TIMEOUT_MS 3000
+#define TIMEOUT_MS		3000
+#define IPS_STATUS_MASK		(IPS_CONFIRMED | IPS_SEEN_REPLY | \
+				 IPS_SRC_NAT_DONE | IPS_DST_NAT_DONE | \
+				 IPS_SRC_NAT | IPS_DST_NAT)
 
 static int connect_to_server(int srv_fd)
 {
···
 	ASSERT_GT(skel->bss->test_delta_timeout, 8, "Test for min ct timeout update");
 	ASSERT_LE(skel->bss->test_delta_timeout, 10, "Test for max ct timeout update");
 	ASSERT_EQ(skel->bss->test_insert_lookup_mark, 77, "Test for insert and lookup mark value");
-	ASSERT_EQ(skel->bss->test_status, IPS_CONFIRMED | IPS_SEEN_REPLY,
-		  "Test for ct status update ");
+	ASSERT_EQ(skel->bss->test_status, IPS_STATUS_MASK, "Test for ct status update ");
 	ASSERT_EQ(skel->data->test_exist_lookup, 0, "Test existing connection lookup");
 	ASSERT_EQ(skel->bss->test_exist_lookup_mark, 43, "Test existing connection lookup ctmark");
+	ASSERT_EQ(skel->data->test_snat_addr, 0, "Test for source natting");
+	ASSERT_EQ(skel->data->test_dnat_addr, 0, "Test for destination natting");
 end:
 	if (srv_client_fd != -1)
 		close(srv_client_fd);

tools/testing/selftests/bpf/progs/test_bpf_nf.c

···
 // SPDX-License-Identifier: GPL-2.0
 #include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
 
 #define EAFNOSUPPORT 97
 #define EPROTO 71
···
 u32 test_delta_timeout = 0;
 u32 test_status = 0;
 u32 test_insert_lookup_mark = 0;
+int test_snat_addr = -EINVAL;
+int test_dnat_addr = -EINVAL;
 __be32 saddr = 0;
 __be16 sport = 0;
 __be32 daddr = 0;
···
 int bpf_ct_change_timeout(struct nf_conn *, u32) __ksym;
 int bpf_ct_set_status(struct nf_conn *, u32) __ksym;
 int bpf_ct_change_status(struct nf_conn *, u32) __ksym;
+int bpf_ct_set_nat_info(struct nf_conn *, union nf_inet_addr *,
+			int port, enum nf_nat_manip_type) __ksym;
 
 static __always_inline void
 nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
···
 	ct = alloc_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
 		      sizeof(opts_def));
 	if (ct) {
+		__u16 sport = bpf_get_prandom_u32();
+		__u16 dport = bpf_get_prandom_u32();
+		union nf_inet_addr saddr = {};
+		union nf_inet_addr daddr = {};
 		struct nf_conn *ct_ins;
 
 		bpf_ct_set_timeout(ct, 10000);
 		ct->mark = 77;
+
+		/* snat */
+		saddr.ip = bpf_get_prandom_u32();
+		bpf_ct_set_nat_info(ct, &saddr, sport, NF_NAT_MANIP_SRC);
+		/* dnat */
+		daddr.ip = bpf_get_prandom_u32();
+		bpf_ct_set_nat_info(ct, &daddr, dport, NF_NAT_MANIP_DST);
 
 		ct_ins = bpf_ct_insert_entry(ct);
 		if (ct_ins) {
···
 			ct_lk = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4),
 					  &opts_def, sizeof(opts_def));
 			if (ct_lk) {
+				struct nf_conntrack_tuple *tuple;
+
+				/* check snat and dnat addresses */
+				tuple = &ct_lk->tuplehash[IP_CT_DIR_REPLY].tuple;
+				if (tuple->dst.u3.ip == saddr.ip &&
+				    tuple->dst.u.all == bpf_htons(sport))
+					test_snat_addr = 0;
+				if (tuple->src.u3.ip == daddr.ip &&
+				    tuple->src.u.all == bpf_htons(dport))
+					test_dnat_addr = 0;
+
 				/* update ct entry timeout */
 				bpf_ct_change_timeout(ct_lk, 10000);
 				test_delta_timeout = ct_lk->timeout - bpf_jiffies64();