test-11-nopriv: check Linux GID permission for unprivileged ping

Signed-off-by: Steven Noonan <steven@uplinklabs.net>

ci/test-11-nopriv.pl

@@ -1,5 +1,6 @@
 #!/usr/bin/perl -w
 
+use English;
 use Test::Command;
 use Test::More;
 
@@ -7,6 +8,26 @@ if( $^O eq 'darwin' ) {
     plan skip_all => 'Test irrelevant on MacOS';
     exit 0;
 }
+
+sub get_ping_gid_range {
+	open FD, "/proc/sys/net/ipv4/ping_group_range" or return undef;
+	chomp(my $line = <FD>);
+	my @range = split(/\s+/, $line);
+	close FD;
+	return @range;
+}
+
+my @gids = split(' ', $EGID);
+my @allowed_gid_range = get_ping_gid_range();
+
+# Linux test for unprivileged ping support
+foreach(@gids) {
+	if ($_ >= $allowed_gid_range[0] && $_ <= $allowed_gid_range[1]) {
+		plan skip_all => "Userspace pings are allowed, gid $_ in range [$allowed_gid_range[0], $allowed_gid_range[1]]";
+		exit 0;
+	}
+}
+
 plan tests => 3;
 
 # run without privileges