samples: bpf: add userspace example for modifying sk_bound_dev_if (ad2805dc) · Commits · e / devices / android_kernel_fairphone_FP4

samples/bpf/Makefile

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		@@ -23,6 +23,7 @@ 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
		@@ -52,6 +53,7 @@ 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

samples/bpf/test_cgrp2_sock.c

0 → 100644

+83 −0

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		/* 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 <net/if.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(),
		};

		return bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, prog, sizeof(prog),
		"GPL", 0);
		}

		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;
		unsigned int idx;

		if (argc < 2)
		return usage(argv[0]);

		idx = if_nametoindex(argv[2]);
		if (!idx) {
		printf("Invalid device name\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_attach(prog_fd, cg_fd, BPF_CGROUP_INET_SOCK_CREATE);
		if (ret < 0) {
		printf("Failed to attach prog to cgroup: '%s'\n",
		strerror(errno));
		return EXIT_FAILURE;
		}

		return EXIT_SUCCESS;
		}

samples/bpf/test_cgrp2_sock.sh

0 → 100755

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		#!/bin/bash

		function config_device {
		ip netns add at_ns0
		ip link add veth0 type veth peer name veth0b
		ip link set veth0b up
		ip link set veth0 netns at_ns0
		ip netns exec at_ns0 ip addr add 172.16.1.100/24 dev veth0
		ip netns exec at_ns0 ip addr add 2401:db00::1/64 dev veth0 nodad
		ip netns exec at_ns0 ip link set dev veth0 up
		ip link add foo type vrf table 1234
		ip link set foo up
		ip addr add 172.16.1.101/24 dev veth0b
		ip addr add 2401:db00::2/64 dev veth0b nodad
		ip link set veth0b master foo
		}

		function attach_bpf {
		rm -rf /tmp/cgroupv2
		mkdir -p /tmp/cgroupv2
		mount -t cgroup2 none /tmp/cgroupv2
		mkdir -p /tmp/cgroupv2/foo
		test_cgrp2_sock /tmp/cgroupv2/foo foo
		echo $$ >> /tmp/cgroupv2/foo/cgroup.procs
		}

		function cleanup {
		set +ex
		ip netns delete at_ns0
		ip link del veth0
		ip link del foo
		umount /tmp/cgroupv2
		rm -rf /tmp/cgroupv2
		set -ex
		}

		function do_test {
		ping -c1 -w1 172.16.1.100
		ping6 -c1 -w1 2401:db00::1
		}

		cleanup 2>/dev/null
		config_device
		attach_bpf
		do_test
		cleanup
		echo "* PASS *"