Add filepath glob support to --security-opt unmask

Want to allow users to specify --security-opt unmask=/proc/*.
This allows us to run podman within podman more securely, then
specifing umask=all, also gives the user more flexibilty.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

pkg/specgen/generate/config_linux_test.go

@@ -0,0 +1,28 @@
+package generate
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestShouldMask(t *testing.T) {
+	tests := []struct {
+		mask       string
+		unmask     []string
+		shouldMask bool
+	}{
+		{"/proc/foo", []string{"all"}, false},
+		{"/proc/foo", []string{"ALL"}, false},
+		{"/proc/foo", []string{"/proc/foo"}, false},
+		{"/proc/foo", []string{"/proc/*"}, false},
+		{"/proc/foo", []string{"/proc/bar", "all"}, false},
+		{"/proc/foo", []string{"/proc/f*"}, false},
+		{"/proc/foo", []string{"/proc/b*"}, true},
+		{"/proc/foo", []string{}, true},
+	}
+	for _, test := range tests {
+		val := shouldMask(test.mask, test.unmask)
+		assert.Equal(t, val, test.shouldMask)
+	}
+}