selftests/net: test classic bpf fanout mode

Test PACKET_FANOUT_CBPF by inserting a cBPF program that selects a
socket by payload. Requires modifying the test program to send
packets with multiple payloads.

Also fix a bug in testing the return value of mmap()

Signed-off-by: Willem de Bruijn <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

tools/testing/selftests/net/psock_fanout.c

···
  *   - PACKET_FANOUT_LB
  *   - PACKET_FANOUT_CPU
  *   - PACKET_FANOUT_ROLLOVER
+ *   - PACKET_FANOUT_CBPF
  *
  * Todo:
  * - functionality: PACKET_FANOUT_FLAG_DEFRAG
···
 
 	ring = mmap(0, req.tp_block_size * req.tp_block_nr,
 		    PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	if (!ring) {
-		fprintf(stderr, "packetsock ring mmap\n");
+	if (ring == MAP_FAILED) {
+		perror("packetsock ring mmap");
 		exit(1);
 	}
 
···
 {
 	const int expect0[] = { 0, 0 };
 	char *rings[2];
+	uint8_t type = typeflags & 0xFF;
 	int fds[2], fds_udp[2][2], ret;
 
 	fprintf(stderr, "test: datapath 0x%hx\n", typeflags);
···
 		fprintf(stderr, "ERROR: failed open\n");
 		exit(1);
 	}
+	if (type == PACKET_FANOUT_CBPF)
+		sock_setfilter(fds[0], SOL_PACKET, PACKET_FANOUT_DATA);
+
 	rings[0] = sock_fanout_open_ring(fds[0]);
 	rings[1] = sock_fanout_open_ring(fds[1]);
 	pair_udp_open(fds_udp[0], PORT_BASE);
···
 
 	/* Send data, but not enough to overflow a queue */
 	pair_udp_send(fds_udp[0], 15);
-	pair_udp_send(fds_udp[1], 5);
+	pair_udp_send_char(fds_udp[1], 5, DATA_CHAR_1);
 	ret = sock_fanout_read(fds, rings, expect1);
 
 	/* Send more data, overflow the queue */
-	pair_udp_send(fds_udp[0], 15);
+	pair_udp_send_char(fds_udp[0], 15, DATA_CHAR_1);
 	/* TODO: ensure consistent order between expect1 and expect2 */
 	ret |= sock_fanout_read(fds, rings, expect2);
 
···
 	const int expect_rb[2][2]	= { { 15, 5 },  { 20, 15 } };
 	const int expect_cpu0[2][2]	= { { 20, 0 },  { 20, 0 } };
 	const int expect_cpu1[2][2]	= { { 0, 20 },  { 0, 20 } };
+	const int expect_bpf[2][2]	= { { 15, 5 },  { 15, 20 } };
 	int port_off = 2, tries = 5, ret;
 
 	test_control_single();
···
 			     port_off, expect_lb[0], expect_lb[1]);
 	ret |= test_datapath(PACKET_FANOUT_ROLLOVER,
 			     port_off, expect_rb[0], expect_rb[1]);
+	ret |= test_datapath(PACKET_FANOUT_CBPF,
+			     port_off, expect_bpf[0], expect_bpf[1]);
 
 	set_cpuaffinity(0);
 	ret |= test_datapath(PACKET_FANOUT_CPU, port_off,

tools/testing/selftests/net/psock_lib.h

···
 
 #define DATA_LEN			100
 #define DATA_CHAR			'a'
+#define DATA_CHAR_1			'b'
 
 #define PORT_BASE			8000
 
···
 # define __maybe_unused		__attribute__ ((__unused__))
 #endif
 
-static __maybe_unused void pair_udp_setfilter(int fd)
+static __maybe_unused void sock_setfilter(int fd, int lvl, int optnum)
 {
 	struct sock_filter bpf_filter[] = {
 		{ 0x80, 0, 0, 0x00000000 },  /* LD  pktlen		      */
-		{ 0x35, 0, 5, DATA_LEN   },  /* JGE DATA_LEN  [f goto nomatch]*/
+		{ 0x35, 0, 4, DATA_LEN   },  /* JGE DATA_LEN  [f goto nomatch]*/
 		{ 0x30, 0, 0, 0x00000050 },  /* LD  ip[80]		      */
-		{ 0x15, 0, 3, DATA_CHAR  },  /* JEQ DATA_CHAR [f goto nomatch]*/
-		{ 0x30, 0, 0, 0x00000051 },  /* LD  ip[81]		      */
-		{ 0x15, 0, 1, DATA_CHAR  },  /* JEQ DATA_CHAR [f goto nomatch]*/
+		{ 0x15, 1, 0, DATA_CHAR  },  /* JEQ DATA_CHAR   [t goto match]*/
+		{ 0x15, 0, 1, DATA_CHAR_1},  /* JEQ DATA_CHAR_1 [t goto match]*/
 		{ 0x06, 0, 0, 0x00000060 },  /* RET match	              */
 		{ 0x06, 0, 0, 0x00000000 },  /* RET no match		      */
 	};
 	struct sock_fprog bpf_prog;
 
+	if (lvl == SOL_PACKET && optnum == PACKET_FANOUT_DATA)
+		bpf_filter[5].code = 0x16;   /* RET A			      */
+
 	bpf_prog.filter = bpf_filter;
 	bpf_prog.len = sizeof(bpf_filter) / sizeof(struct sock_filter);
-	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &bpf_prog,
+	if (setsockopt(fd, lvl, optnum, &bpf_prog,
 		       sizeof(bpf_prog))) {
 		perror("setsockopt SO_ATTACH_FILTER");
 		exit(1);
 	}
+}
+
+static __maybe_unused void pair_udp_setfilter(int fd)
+{
+	sock_setfilter(fd, SOL_SOCKET, SO_ATTACH_FILTER);
 }
 
 static __maybe_unused void pair_udp_open(int fds[], uint16_t port)
···
 	}
 }
 
-static __maybe_unused void pair_udp_send(int fds[], int num)
+static __maybe_unused void pair_udp_send_char(int fds[], int num, char payload)
 {
 	char buf[DATA_LEN], rbuf[DATA_LEN];
 
-	memset(buf, DATA_CHAR, sizeof(buf));
+	memset(buf, payload, sizeof(buf));
 	while (num--) {
 		/* Should really handle EINTR and EAGAIN */
 		if (write(fds[0], buf, sizeof(buf)) != sizeof(buf)) {
···
 			exit(1);
 		}
 	}
+}
+
+static __maybe_unused void pair_udp_send(int fds[], int num)
+{
+	return pair_udp_send_char(fds, num, DATA_CHAR);
 }
 
 static __maybe_unused void pair_udp_close(int fds[])