bpf: Enable bpf_{g,s}etsockopt in BPF_CGROUP_UDP{4,6}_SENDMSG

Can be used to query/modify socket state for unconnected UDP sendmsg.
Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on
a locked socket.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-2-sdf@google.com

1 files changed, 21 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/bpf_sockopt_helpers.h b/tools/testing/selftests/bpf/bpf_sockopt_helpers.h
new file mode 100644
index 000000000000..11f3a0976174
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpf_sockopt_helpers.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <sys/socket.h>
+#include <bpf/bpf_helpers.h>
+
+int get_set_sk_priority(void *ctx)
+{
+	int prio;
+
+	/* Verify that context allows calling bpf_getsockopt and
+	 * bpf_setsockopt by reading and writing back socket
+	 * priority.
+	 */
+
+	if (bpf_getsockopt(ctx, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))
+		return 0;
+	if (bpf_setsockopt(ctx, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))
+		return 0;
+
+	return 1;
+}