selftests: net: ip_defrag: ignore EPERM

When running with conntrack rules, the dropped overlap fragments may cause
EPERM to be returned to sendto. Instead of completely failing, just ignore
those errors and continue. If this causes packets with overlap fragments to
be dropped as expected, that is okay. And if it causes packets that are
expected to be received to be dropped, which should not happen, it will be
detected as failure.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/ip_defrag.c

@@ -192,9 +192,9 @@ static void send_fragment(int fd_raw, struct sockaddr *addr, socklen_t alen,
 	}
 
 	res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen);
-	if (res < 0)
+	if (res < 0 && errno != EPERM)
 		error(1, errno, "send_fragment");
-	if (res != frag_len)
+	if (res >= 0 && res != frag_len)
 		error(1, 0, "send_fragment: %d vs %d", res, frag_len);
 
 	frag_counter++;
@@ -313,9 +313,9 @@ static void send_udp_frags(int fd_raw, struct sockaddr *addr,
 			iphdr->ip_len = htons(frag_len);
 		}
 		res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen);
-		if (res < 0)
+		if (res < 0 && errno != EPERM)
 			error(1, errno, "sendto overlap: %d", frag_len);
-		if (res != frag_len)
+		if (res >= 0 && res != frag_len)
 			error(1, 0, "sendto overlap: %d vs %d", (int)res, frag_len);
 		frag_counter++;
 	}