diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index f394ac616ed8ea37b1929236ce862ac2260039d7..fb17206ddb57a4c11fd7f526792f9a619fcb450e 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -22,6 +22,7 @@ hostprogs-y += spintest
hostprogs-y += map_perf_test
hostprogs-y += test_overhead
hostprogs-y += test_cgrp2_array_pin
+hostprogs-y += test_cgrp2_attach
hostprogs-y += xdp1
hostprogs-y += xdp2
hostprogs-y += test_current_task_under_cgroup
@@ -49,6 +50,7 @@ spintest-objs := bpf_load.o libbpf.o spintest_user.o
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
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/libbpf.c b/samples/bpf/libbpf.c
index 9969e35550c3dd3c9702e7e99dab35b3df9fb7f6..9ce707bf02a7a7aee8e37383af34429d97c569cf 100644
--- a/samples/bpf/libbpf.c
+++ b/samples/bpf/libbpf.c
@@ -104,6 +104,27 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
}
+int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type)
+{
+ union bpf_attr attr = {
+ .target_fd = target_fd,
+ .attach_bpf_fd = prog_fd,
+ .attach_type = type,
+ };
+
+ return syscall(__NR_bpf, BPF_PROG_ATTACH, &attr, sizeof(attr));
+}
+
+int bpf_prog_detach(int target_fd, enum bpf_attach_type type)
+{
+ union bpf_attr attr = {
+ .target_fd = target_fd,
+ .attach_type = type,
+ };
+
+ return syscall(__NR_bpf, BPF_PROG_DETACH, &attr, sizeof(attr));
+}
+
int bpf_obj_pin(int fd, const char *pathname)
{
union bpf_attr attr = {
diff --git a/samples/bpf/libbpf.h b/samples/bpf/libbpf.h
index de96a935068d13857c6779ddef5d0422455149e3..94a901d86fc2ea4867a3993f87380e9894d3b1f5 100644
--- a/samples/bpf/libbpf.h
+++ b/samples/bpf/libbpf.h
@@ -15,6 +15,9 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, int insn_len,
const char *license, int kern_version);
+int bpf_prog_attach(int prog_fd, int attachable_fd, enum bpf_attach_type type);
+int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);
+
int bpf_obj_pin(int fd, const char *pathname);
int bpf_obj_get(const char *pathname);
diff --git a/samples/bpf/test_cgrp2_attach.c b/samples/bpf/test_cgrp2_attach.c
new file mode 100644
index 0000000000000000000000000000000000000000..63ef2083f766b9e319ae4a43bdf4fb7095e5d855
--- /dev/null
+++ b/samples/bpf/test_cgrp2_attach.c
@@ -0,0 +1,147 @@
+/* eBPF example program:
+ *
+ * - Creates arraymap in kernel with 4 bytes keys and 8 byte values
+ *
+ * - Loads eBPF program
+ *
+ * The eBPF program accesses the map passed in to store two pieces of
+ * information. The number of invocations of the program, which maps
+ * to the number of packets received, is stored to key 0. Key 1 is
+ * incremented on each iteration by the number of bytes stored in
+ * the skb.
+ *
+ * - Detaches any eBPF program previously attached to the cgroup
+ *
+ * - Attaches the new program to a cgroup using BPF_PROG_ATTACH
+ *
+ * - Every second, reads map[0] and map[1] to see how many bytes and
+ * packets were seen on any socket of tasks in the given cgroup.
+ */
+
+#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"
+
+enum {
+ MAP_KEY_PACKETS,
+ MAP_KEY_BYTES,
+};
+
+static int prog_load(int map_fd, int verdict)
+{
+ struct bpf_insn prog[] = {
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), /* save r6 so it's not clobbered by BPF_CALL */
+
+ /* Count packets */
+ BPF_MOV64_IMM(BPF_REG_0, MAP_KEY_PACKETS), /* r0 = 0 */
+ BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */
+ BPF_LD_MAP_FD(BPF_REG_1, map_fd), /* load map fd to r1 */
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */
+ BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */
+
+ /* Count bytes */
+ BPF_MOV64_IMM(BPF_REG_0, MAP_KEY_BYTES), /* r0 = 1 */
+ BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */
+ BPF_LD_MAP_FD(BPF_REG_1, map_fd),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+ BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6, offsetof(struct __sk_buff, len)), /* r1 = skb->len */
+ BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */
+
+ BPF_MOV64_IMM(BPF_REG_0, verdict), /* r0 = verdict */
+ BPF_EXIT_INSN(),
+ };
+
+ return bpf_prog_load(BPF_PROG_TYPE_CGROUP_SKB,
+ prog, sizeof(prog), "GPL", 0);
+}
+
+static int usage(const char *argv0)
+{
+ printf("Usage: %s <cg-path> <egress|ingress> [drop]\n", argv0);
+ return EXIT_FAILURE;
+}
+
+int main(int argc, char **argv)
+{
+ int cg_fd, map_fd, prog_fd, key, ret;
+ long long pkt_cnt, byte_cnt;
+ enum bpf_attach_type type;
+ int verdict = 1;
+
+ if (argc < 3)
+ return usage(argv[0]);
+
+ if (strcmp(argv[2], "ingress") == 0)
+ type = BPF_CGROUP_INET_INGRESS;
+ else if (strcmp(argv[2], "egress") == 0)
+ type = BPF_CGROUP_INET_EGRESS;
+ else
+ return usage(argv[0]);
+
+ if (argc > 3 && strcmp(argv[3], "drop") == 0)
+ verdict = 0;
+
+ 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;
+ }
+
+ map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY,
+ sizeof(key), sizeof(byte_cnt),
+ 256, 0);
+ if (map_fd < 0) {
+ printf("Failed to create map: '%s'\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ prog_fd = prog_load(map_fd, verdict);
+ 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, type);
+ printf("bpf_prog_detach() returned '%s' (%d)\n", strerror(errno), errno);
+
+ ret = bpf_prog_attach(prog_fd, cg_fd, type);
+ if (ret < 0) {
+ printf("Failed to attach prog to cgroup: '%s'\n",
+ strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ while (1) {
+ key = MAP_KEY_PACKETS;
+ assert(bpf_lookup_elem(map_fd, &key, &pkt_cnt) == 0);
+
+ key = MAP_KEY_BYTES;
+ assert(bpf_lookup_elem(map_fd, &key, &byte_cnt) == 0);
+
+ printf("cgroup received %lld packets, %lld bytes\n",
+ pkt_cnt, byte_cnt);
+ sleep(1);
+ }
+
+ return EXIT_SUCCESS;
+}