selftests: xsk: Add tests for invalid xsk descriptors

Add tests for invalid xsk descriptors in the Tx ring. A number of
handcrafted nasty invalid descriptors are created and submitted to the
tx ring to check that they are validated correctly. Corner case valid
ones are also sent. The tests are run for both aligned and unaligned
mode.

pkt_stream_set() is introduced to be able to create a hand-crafted
packet stream where every single packet is specified in detail.
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210907071928.9750-20-magnus.karlsson@gmail.com

tools/testing/selftests/bpf/xdpxceiver.c

@@ -46,6 +46,8 @@
  *       then remove xsk sockets from queue 0 on both veth interfaces and
  *       finally run a traffic on queues ids 1
  *    g. unaligned mode
+ *    h. tests for invalid and corner case Tx descriptors so that the correct ones
+ *       are discarded and let through, respectively.
  *
  * Total tests: 12
  *
@@ -394,7 +396,7 @@ static void __test_spec_init(struct test_spec *test, struct ifobject *ifobj_tx,
 		for (j = 0; j < MAX_SOCKETS; j++) {
 			memset(&ifobj->umem_arr[j], 0, sizeof(ifobj->umem_arr[j]));
 			memset(&ifobj->xsk_arr[j], 0, sizeof(ifobj->xsk_arr[j]));
-			ifobj->umem_arr[j].num_frames = DEFAULT_PKT_CNT / 4;
+			ifobj->umem_arr[j].num_frames = DEFAULT_UMEM_BUFFERS;
 			ifobj->umem_arr[j].frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
 			ifobj->xsk_arr[j].rxqsize = XSK_RING_CONS__DEFAULT_NUM_DESCS;
 		}
@@ -450,6 +452,16 @@ static struct pkt *pkt_stream_get_pkt(struct pkt_stream *pkt_stream, u32 pkt_nb)
 	return &pkt_stream->pkts[pkt_nb];
 }
 
+static struct pkt *pkt_stream_get_next_rx_pkt(struct pkt_stream *pkt_stream)
+{
+	while (pkt_stream->rx_pkt_nb < pkt_stream->nb_pkts) {
+		if (pkt_stream->pkts[pkt_stream->rx_pkt_nb].valid)
+			return &pkt_stream->pkts[pkt_stream->rx_pkt_nb++];
+		pkt_stream->rx_pkt_nb++;
+	}
+	return NULL;
+}
+
 static void pkt_stream_delete(struct pkt_stream *pkt_stream)
 {
 	free(pkt_stream->pkts);
@@ -465,17 +477,31 @@ static void pkt_stream_restore_default(struct test_spec *test)
 	test->ifobj_rx->pkt_stream = test->pkt_stream_default;
 }
 
-static struct pkt_stream *pkt_stream_generate(struct xsk_umem_info *umem, u32 nb_pkts, u32 pkt_len)
+static struct pkt_stream *__pkt_stream_alloc(u32 nb_pkts)
 {
 	struct pkt_stream *pkt_stream;
-	u32 i;
 
 	pkt_stream = calloc(1, sizeof(*pkt_stream));
 	if (!pkt_stream)
-		exit_with_error(ENOMEM);
+		return NULL;
 
 	pkt_stream->pkts = calloc(nb_pkts, sizeof(*pkt_stream->pkts));
-	if (!pkt_stream->pkts)
+	if (!pkt_stream->pkts) {
+		free(pkt_stream);
+		return NULL;
+	}
+
+	pkt_stream->nb_pkts = nb_pkts;
+	return pkt_stream;
+}
+
+static struct pkt_stream *pkt_stream_generate(struct xsk_umem_info *umem, u32 nb_pkts, u32 pkt_len)
+{
+	struct pkt_stream *pkt_stream;
+	u32 i;
+
+	pkt_stream = __pkt_stream_alloc(nb_pkts);
+	if (!pkt_stream)
 		exit_with_error(ENOMEM);
 
 	pkt_stream->nb_pkts = nb_pkts;
@@ -535,6 +561,8 @@ static struct pkt *pkt_generate(struct ifobject *ifobject, u32 pkt_nb)
 
 	if (!pkt)
 		return NULL;
+	if (!pkt->valid || pkt->len < PKT_SIZE)
+		return pkt;
 
 	data = xsk_umem__get_data(ifobject->umem->buffer, pkt->addr);
 	udp_hdr = (struct udphdr *)(data + sizeof(struct ethhdr) + sizeof(struct iphdr));
@@ -549,6 +577,26 @@ static struct pkt *pkt_generate(struct ifobject *ifobject, u32 pkt_nb)
 	return pkt;
 }
 
+static void pkt_stream_generate_custom(struct test_spec *test, struct pkt *pkts, u32 nb_pkts)
+{
+	struct pkt_stream *pkt_stream;
+	u32 i;
+
+	pkt_stream = __pkt_stream_alloc(nb_pkts);
+	if (!pkt_stream)
+		exit_with_error(ENOMEM);
+
+	test->ifobj_tx->pkt_stream = pkt_stream;
+	test->ifobj_rx->pkt_stream = pkt_stream;
+
+	for (i = 0; i < nb_pkts; i++) {
+		pkt_stream->pkts[i].addr = pkts[i].addr;
+		pkt_stream->pkts[i].len = pkts[i].len;
+		pkt_stream->pkts[i].payload = i;
+		pkt_stream->pkts[i].valid = pkts[i].valid;
+	}
+}
+
 static void pkt_dump(void *pkt, u32 len)
 {
 	char s[INET_ADDRSTRLEN];
@@ -596,19 +644,24 @@ static bool is_pkt_valid(struct pkt *pkt, void *buffer, u64 addr, u32 len)
 		return false;
 	}
 
+	if (len < PKT_SIZE) {
+		/*Do not try to verify packets that are smaller than minimum size. */
+		return true;
+	}
+
+	if (pkt->len != len) {
+		ksft_test_result_fail
+			("ERROR: [%s] expected length [%d], got length [%d]\n",
+			 __func__, pkt->len, len);
+		return false;
+	}
+
 	if (iphdr->version == IP_PKT_VER && iphdr->tos == IP_PKT_TOS) {
 		u32 seqnum = ntohl(*((u32 *)(data + PKT_HDR_SIZE)));
 
 		if (opt_pkt_dump)
 			pkt_dump(data, PKT_SIZE);
 
-		if (pkt->len != len) {
-			ksft_test_result_fail
-				("ERROR: [%s] expected length [%d], got length [%d]\n",
-					__func__, pkt->len, len);
-			return false;
-		}
-
 		if (pkt->payload != seqnum) {
 			ksft_test_result_fail
 				("ERROR: [%s] expected seqnum [%d], got seqnum [%d]\n",
@@ -645,6 +698,15 @@ static void complete_pkts(struct xsk_socket_info *xsk, int batch_size)
 
 	rcvd = xsk_ring_cons__peek(&xsk->umem->cq, batch_size, &idx);
 	if (rcvd) {
+		if (rcvd > xsk->outstanding_tx) {
+			u64 addr = *xsk_ring_cons__comp_addr(&xsk->umem->cq, idx + rcvd - 1);
+
+			ksft_test_result_fail("ERROR: [%s] Too many packets completed\n",
+					      __func__);
+			ksft_print_msg("Last completion address: %llx\n", addr);
+			return;
+		}
+
 		xsk_ring_cons__release(&xsk->umem->cq, rcvd);
 		xsk->outstanding_tx -= rcvd;
 	}
@@ -653,11 +715,10 @@ static void complete_pkts(struct xsk_socket_info *xsk, int batch_size)
 static void receive_pkts(struct pkt_stream *pkt_stream, struct xsk_socket_info *xsk,
 			 struct pollfd *fds)
 {
-	u32 idx_rx = 0, idx_fq = 0, rcvd, i, pkt_count = 0;
-	struct pkt *pkt;
+	struct pkt *pkt = pkt_stream_get_next_rx_pkt(pkt_stream);
+	u32 idx_rx = 0, idx_fq = 0, rcvd, i;
 	int ret;
 
-	pkt = pkt_stream_get_pkt(pkt_stream, pkt_count++);
 	while (pkt) {
 		rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx);
 		if (!rcvd) {
@@ -685,13 +746,21 @@ static void receive_pkts(struct pkt_stream *pkt_stream, struct xsk_socket_info *
 			const struct xdp_desc *desc = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx++);
 			u64 addr = desc->addr, orig;
 
+			if (!pkt) {
+				ksft_test_result_fail("ERROR: [%s] Received too many packets.\n",
+						      __func__);
+				ksft_print_msg("Last packet has addr: %llx len: %u\n",
+					       addr, desc->len);
+				return;
+			}
+
 			orig = xsk_umem__extract_addr(addr);
 			addr = xsk_umem__add_offset_to_addr(addr);
 			if (!is_pkt_valid(pkt, xsk->umem->buffer, addr, desc->len))
 				return;
 
 			*xsk_ring_prod__fill_addr(&xsk->umem->fq, idx_fq++) = orig;
-			pkt = pkt_stream_get_pkt(pkt_stream, pkt_count++);
+			pkt = pkt_stream_get_next_rx_pkt(pkt_stream);
 		}
 
 		xsk_ring_prod__submit(&xsk->umem->fq, rcvd);
@@ -875,6 +944,7 @@ static void testapp_cleanup_xsk_res(struct ifobject *ifobj)
 {
 	print_verbose("Destroying socket\n");
 	xsk_socket__delete(ifobj->xsk->xsk);
+	munmap(ifobj->umem->buffer, ifobj->umem->num_frames * ifobj->umem->frame_size);
 	xsk_umem__delete(ifobj->umem->umem);
 }
 
@@ -1118,6 +1188,35 @@ static bool testapp_unaligned(struct test_spec *test)
 	return true;
 }
 
+static void testapp_invalid_desc(struct test_spec *test)
+{
+	struct pkt pkts[] = {
+		/* Zero packet length at address zero allowed */
+		{0, 0, 0, true},
+		/* Zero packet length allowed */
+		{0x1000, 0, 0, true},
+		/* Straddling the start of umem */
+		{-2, PKT_SIZE, 0, false},
+		/* Packet too large */
+		{0x2000, XSK_UMEM__INVALID_FRAME_SIZE, 0, false},
+		/* After umem ends */
+		{UMEM_SIZE, PKT_SIZE, 0, false},
+		/* Straddle the end of umem */
+		{UMEM_SIZE - PKT_SIZE / 2, PKT_SIZE, 0, false},
+		/* Straddle a page boundrary */
+		{0x3000 - PKT_SIZE / 2, PKT_SIZE, 0, false},
+		/* Valid packet for synch so that something is received */
+		{0x4000, PKT_SIZE, 0, true}};
+
+	if (test->ifobj_tx->umem->unaligned_mode) {
+		/* Crossing a page boundrary allowed */
+		pkts[6].valid = true;
+	}
+	pkt_stream_generate_custom(test, pkts, ARRAY_SIZE(pkts));
+	testapp_validate_traffic(test);
+	pkt_stream_restore_default(test);
+}
+
 static void init_iface(struct ifobject *ifobj, const char *dst_mac, const char *src_mac,
 		       const char *dst_ip, const char *src_ip, const u16 dst_port,
 		       const u16 src_port, thread_func_t func_ptr)
@@ -1159,7 +1258,7 @@ static void run_pkt_test(struct test_spec *test, enum test_mode mode, enum test_
 	case TEST_TYPE_BPF_RES:
 		testapp_bpf_res(test);
 		break;
-	case TEST_TYPE_NOPOLL:
+	case TEST_TYPE_RUN_TO_COMPLETION:
 		test_spec_set_name(test, "RUN_TO_COMPLETION");
 		testapp_validate_traffic(test);
 		break;
@@ -1169,6 +1268,16 @@ static void run_pkt_test(struct test_spec *test, enum test_mode mode, enum test_
 		test_spec_set_name(test, "POLL");
 		testapp_validate_traffic(test);
 		break;
+	case TEST_TYPE_ALIGNED_INV_DESC:
+		test_spec_set_name(test, "ALIGNED_INV_DESC");
+		testapp_invalid_desc(test);
+		break;
+	case TEST_TYPE_UNALIGNED_INV_DESC:
+		test_spec_set_name(test, "UNALIGNED_INV_DESC");
+		test->ifobj_tx->umem->unaligned_mode = true;
+		test->ifobj_rx->umem->unaligned_mode = true;
+		testapp_invalid_desc(test);
+		break;
 	case TEST_TYPE_UNALIGNED:
 		if (!testapp_unaligned(test))
 			return;

tools/testing/selftests/bpf/xdpxceiver.h

@@ -38,6 +38,8 @@
 #define BATCH_SIZE 8
 #define POLL_TMOUT 1000
 #define DEFAULT_PKT_CNT (4 * 1024)
+#define DEFAULT_UMEM_BUFFERS (DEFAULT_PKT_CNT / 4)
+#define UMEM_SIZE (DEFAULT_UMEM_BUFFERS * XSK_UMEM__DEFAULT_FRAME_SIZE)
 #define RX_FULL_RXQSIZE 32
 #define DEFAULT_OFFSET 256
 #define XSK_UMEM__INVALID_FRAME_SIZE (XSK_UMEM__DEFAULT_FRAME_SIZE + 1)
@@ -51,9 +53,11 @@ enum test_mode {
 };
 
 enum test_type {
-	TEST_TYPE_NOPOLL,
+	TEST_TYPE_RUN_TO_COMPLETION,
 	TEST_TYPE_POLL,
 	TEST_TYPE_UNALIGNED,
+	TEST_TYPE_ALIGNED_INV_DESC,
+	TEST_TYPE_UNALIGNED_INV_DESC,
 	TEST_TYPE_TEARDOWN,
 	TEST_TYPE_BIDI,
 	TEST_TYPE_STATS,
@@ -104,6 +108,7 @@ struct pkt {
 
 struct pkt_stream {
 	u32 nb_pkts;
+	u32 rx_pkt_nb;
 	struct pkt *pkts;
 	bool use_addr_for_fill;
 };