From ad2805dc79e647ec2aee931a51924fda9d03b2fc Mon Sep 17 00:00:00 2001 From: David Ahern Date: Thu, 1 Dec 2016 08:48:05 -0800 Subject: samples: bpf: add userspace example for modifying sk_bound_dev_if 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. Signed-off-by: David Ahern Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/Makefile | 2 + samples/bpf/test_cgrp2_sock.c | 83 ++++++++++++++++++++++++++++++++++++++++++ samples/bpf/test_cgrp2_sock.sh | 47 ++++++++++++++++++++++++ 3 files changed, 132 insertions(+) create mode 100644 samples/bpf/test_cgrp2_sock.c create mode 100755 samples/bpf/test_cgrp2_sock.sh (limited to 'samples') diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 44532fbe4cae..e1700c8e0f66 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -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 diff --git a/samples/bpf/test_cgrp2_sock.c b/samples/bpf/test_cgrp2_sock.c new file mode 100644 index 000000000000..d467b3c1c55c --- /dev/null +++ b/samples/bpf/test_cgrp2_sock.c @@ -0,0 +1,83 @@ +/* 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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; +} diff --git a/samples/bpf/test_cgrp2_sock.sh b/samples/bpf/test_cgrp2_sock.sh new file mode 100755 index 000000000000..925fd467c7cc --- /dev/null +++ b/samples/bpf/test_cgrp2_sock.sh @@ -0,0 +1,47 @@ +#!/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 ***" -- cgit