bpf: fix rlimit in reuseport net selftest

Fix two issues in the reuseport_bpf selftests that were
reported by Linaro CI:

  [...]
  + ./reuseport_bpf
  ---- IPv4 UDP ----
  Testing EBPF mod 10...
  Reprograming, testing mod 5...
  ./reuseport_bpf: ebpf error. log:
  0: (bf) r6 = r1
  1: (20) r0 = *(u32 *)skb[0]
  2: (97) r0 %= 10
  3: (95) exit
  processed 4 insns
  : Operation not permitted
  + echo FAIL
  [...]
  ---- IPv4 TCP ----
  Testing EBPF mod 10...
  ./reuseport_bpf: failed to bind send socket: Address already in use
  + echo FAIL
  [...]

For the former adjust rlimit since this was the cause of
failure for loading the BPF prog, and for the latter add
SO_REUSEADDR.

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Link: https://bugs.linaro.org/show_bug.cgi?id=3502
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/reuseport_bpf.c

@@ -21,6 +21,7 @@
 #include <sys/epoll.h>
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/resource.h>
 #include <unistd.h>
 
 #ifndef ARRAY_SIZE
@@ -190,11 +191,14 @@ static void send_from(struct test_params p, uint16_t sport, char *buf,
 	struct sockaddr * const saddr = new_any_sockaddr(p.send_family, sport);
 	struct sockaddr * const daddr =
 		new_loopback_sockaddr(p.send_family, p.recv_port);
-	const int fd = socket(p.send_family, p.protocol, 0);
+	const int fd = socket(p.send_family, p.protocol, 0), one = 1;
 
 	if (fd < 0)
 		error(1, errno, "failed to create send socket");
 
+	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)))
+		error(1, errno, "failed to set reuseaddr");
+
 	if (bind(fd, saddr, sockaddr_size()))
 		error(1, errno, "failed to bind send socket");
 
@@ -433,6 +437,21 @@ void enable_fastopen(void)
 	}
 }
 
+static struct rlimit rlim_old, rlim_new;
+
+static  __attribute__((constructor)) void main_ctor(void)
+{
+	getrlimit(RLIMIT_MEMLOCK, &rlim_old);
+	rlim_new.rlim_cur = rlim_old.rlim_cur + (1UL << 20);
+	rlim_new.rlim_max = rlim_old.rlim_max + (1UL << 20);
+	setrlimit(RLIMIT_MEMLOCK, &rlim_new);
+}
+
+static __attribute__((destructor)) void main_dtor(void)
+{
+	setrlimit(RLIMIT_MEMLOCK, &rlim_old);
+}
+
 int main(void)
 {
 	fprintf(stderr, "---- IPv4 UDP ----\n");