Add a simple program to demonstrate the ability to attach a bpf program
to a cgroup that sets sk_bound_dev_if for AF_INET{6} sockets when they
are created.
v2
- removed bpf_sock_store_u32 references
- changed BPF_CGROUP_INET_SOCK_CREATE to BPF_CGROUP_INET_SOCK
- remove BPF_PROG_TYPE_CGROUP_SOCK prog type and add prog_subtype
Signed-off-by: David Ahern <d...@cumulusnetworks.com>
---
samples/bpf/Makefile | 2 ++
samples/bpf/test_cgrp2_sock.c | 84 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+)
create mode 100644 samples/bpf/test_cgrp2_sock.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 2624d5d7ce8b..ec4ef37a2dbc 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -22,6 +22,7 @@ hostprogs-y += map_perf_test
hostprogs-y += test_overhead
hostprogs-y += test_cgrp2_array_pin
hostprogs-y += test_cgrp2_attach
+hostprogs-y += test_cgrp2_sock
hostprogs-y += xdp1
hostprogs-y += xdp2
hostprogs-y += test_current_task_under_cgroup
@@ -48,6 +49,7 @@ map_perf_test-objs := bpf_load.o libbpf.o map_perf_test_user.o
test_overhead-objs := bpf_load.o libbpf.o test_overhead_user.o
test_cgrp2_array_pin-objs := libbpf.o test_cgrp2_array_pin.o
test_cgrp2_attach-objs := libbpf.o test_cgrp2_attach.o
+test_cgrp2_sock-objs := libbpf.o test_cgrp2_sock.o
xdp1-objs := bpf_load.o libbpf.o xdp1_user.o
# reuse xdp1 source intentionally
xdp2-objs := bpf_load.o libbpf.o xdp1_user.o
diff --git a/samples/bpf/test_cgrp2_sock.c b/samples/bpf/test_cgrp2_sock.c
new file mode 100644
index 000000000000..9cc3307052e0
--- /dev/null
+++ b/samples/bpf/test_cgrp2_sock.c
@@ -0,0 +1,84 @@
+/* eBPF example program:
+ *
+ * - Loads eBPF program
+ *
+ * The eBPF program sets the sk_bound_dev_if index in new AF_INET{6}
+ * sockets opened by processes in the cgroup.
+ *
+ * - Attaches the new program to a cgroup using BPF_PROG_ATTACH
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <string.h>
+#include <unistd.h>
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/bpf.h>
+
+#include "libbpf.h"
+
+static int prog_load(int idx)
+{
+ struct bpf_insn prog[] = {
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+ BPF_MOV64_IMM(BPF_REG_3, idx),
+ BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock,
bound_dev_if)),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct
bpf_sock, bound_dev_if)),
+ BPF_MOV64_IMM(BPF_REG_0, 1), /* r0 = verdict */
+ BPF_EXIT_INSN(),
+ };
+ union bpf_prog_subtype prog_subtype = { .cgroup.sock = 1 };
+
+ return bpf_prog_load(BPF_PROG_TYPE_CGROUP, prog, sizeof(prog), "GPL",
+ 0, &prog_subtype);
+}
+
+static int usage(const char *argv0)
+{
+ printf("Usage: %s <cg-path> device-index\n", argv0);
+ return EXIT_FAILURE;
+}
+
+int main(int argc, char **argv)
+{
+ int cg_fd, prog_fd, ret;
+ int idx = 0;
+
+ if (argc < 2)
+ return usage(argv[0]);
+
+ idx = atoi(argv[2]);
+ if (!idx) {
+ printf("Invalid device index\n");
+ return EXIT_FAILURE;
+ }
+
+ cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
+ if (cg_fd < 0) {
+ printf("Failed to open cgroup path: '%s'\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ prog_fd = prog_load(idx);
+ printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf);
+
+ if (prog_fd < 0) {
+ printf("Failed to load prog: '%s'\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ ret = bpf_prog_detach(cg_fd, BPF_CGROUP_INET_SOCK);
+ ret = bpf_prog_attach(prog_fd, cg_fd, BPF_CGROUP_INET_SOCK);
+ if (ret < 0) {
+ printf("Failed to attach prog to cgroup: '%s'\n",
+ strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ return EXIT_SUCCESS;
+}
--
2.1.4
