From 554ae6e792ef38020b80b4d5127c51d510c0918f Mon Sep 17 00:00:00 2001 From: David Ahern Date: Thu, 1 Dec 2016 08:48:08 -0800 Subject: samples/bpf: add userspace example for prohibiting sockets Add examples preventing a process in a cgroup from opening a socket based family, protocol and type. Signed-off-by: David Ahern Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/Makefile | 4 ++ samples/bpf/sock_flags_kern.c | 44 ++++++++++++++++++++++ samples/bpf/test_cgrp2_sock2.c | 66 +++++++++++++++++++++++++++++++++ samples/bpf/test_cgrp2_sock2.sh | 81 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 195 insertions(+) create mode 100644 samples/bpf/sock_flags_kern.c create mode 100644 samples/bpf/test_cgrp2_sock2.c create mode 100755 samples/bpf/test_cgrp2_sock2.sh (limited to 'samples') diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index e1700c8..bfc2cb8 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -24,6 +24,7 @@ hostprogs-y += test_overhead hostprogs-y += test_cgrp2_array_pin hostprogs-y += test_cgrp2_attach hostprogs-y += test_cgrp2_sock +hostprogs-y += test_cgrp2_sock2 hostprogs-y += xdp1 hostprogs-y += xdp2 hostprogs-y += test_current_task_under_cgroup @@ -54,6 +55,7 @@ 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 +test_cgrp2_sock2-objs := bpf_load.o libbpf.o test_cgrp2_sock2.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 @@ -75,6 +77,7 @@ always += tracex3_kern.o always += tracex4_kern.o always += tracex5_kern.o always += tracex6_kern.o +always += sock_flags_kern.o always += test_probe_write_user_kern.o always += trace_output_kern.o always += tcbpf1_kern.o @@ -109,6 +112,7 @@ HOSTLOADLIBES_tracex3 += -lelf HOSTLOADLIBES_tracex4 += -lelf -lrt HOSTLOADLIBES_tracex5 += -lelf HOSTLOADLIBES_tracex6 += -lelf +HOSTLOADLIBES_test_cgrp2_sock2 += -lelf HOSTLOADLIBES_test_probe_write_user += -lelf HOSTLOADLIBES_trace_output += -lelf -lrt HOSTLOADLIBES_lathist += -lelf diff --git a/samples/bpf/sock_flags_kern.c b/samples/bpf/sock_flags_kern.c new file mode 100644 index 0000000..533dd11a6 --- /dev/null +++ b/samples/bpf/sock_flags_kern.c @@ -0,0 +1,44 @@ +#include +#include +#include +#include +#include +#include "bpf_helpers.h" + +SEC("cgroup/sock1") +int bpf_prog1(struct bpf_sock *sk) +{ + char fmt[] = "socket: family %d type %d protocol %d\n"; + + bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol); + + /* block PF_INET6, SOCK_RAW, IPPROTO_ICMPV6 sockets + * ie., make ping6 fail + */ + if (sk->family == PF_INET6 && + sk->type == SOCK_RAW && + sk->protocol == IPPROTO_ICMPV6) + return 0; + + return 1; +} + +SEC("cgroup/sock2") +int bpf_prog2(struct bpf_sock *sk) +{ + char fmt[] = "socket: family %d type %d protocol %d\n"; + + bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol); + + /* block PF_INET, SOCK_RAW, IPPROTO_ICMP sockets + * ie., make ping fail + */ + if (sk->family == PF_INET && + sk->type == SOCK_RAW && + sk->protocol == IPPROTO_ICMP) + return 0; + + return 1; +} + +char _license[] SEC("license") = "GPL"; diff --git a/samples/bpf/test_cgrp2_sock2.c b/samples/bpf/test_cgrp2_sock2.c new file mode 100644 index 0000000..455ef0d --- /dev/null +++ b/samples/bpf/test_cgrp2_sock2.c @@ -0,0 +1,66 @@ +/* eBPF example program: + * + * - Loads eBPF program + * + * The eBPF program loads a filter from file and attaches the + * program to a cgroup using BPF_PROG_ATTACH + */ + +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "libbpf.h" +#include "bpf_load.h" + +static int usage(const char *argv0) +{ + printf("Usage: %s cg-path filter-path [filter-id]\n", argv0); + return EXIT_FAILURE; +} + +int main(int argc, char **argv) +{ + int cg_fd, ret, filter_id = 0; + + if (argc < 3) + return usage(argv[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; + } + + if (load_bpf_file(argv[2])) + return EXIT_FAILURE; + + printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf); + + if (argc > 3) + filter_id = atoi(argv[3]); + + if (filter_id > prog_cnt) { + printf("Invalid program id; program not found in file\n"); + return EXIT_FAILURE; + } + + ret = bpf_prog_attach(prog_fd[filter_id], 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_sock2.sh b/samples/bpf/test_cgrp2_sock2.sh new file mode 100755 index 0000000..891f12a --- /dev/null +++ b/samples/bpf/test_cgrp2_sock2.sh @@ -0,0 +1,81 @@ +#!/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 addr add 172.16.1.101/24 dev veth0b + ip addr add 2401:db00::2/64 dev veth0b nodad +} + +function config_cgroup { + rm -rf /tmp/cgroupv2 + mkdir -p /tmp/cgroupv2 + mount -t cgroup2 none /tmp/cgroupv2 + mkdir -p /tmp/cgroupv2/foo + echo $$ >> /tmp/cgroupv2/foo/cgroup.procs +} + + +function attach_bpf { + test_cgrp2_sock2 /tmp/cgroupv2/foo sock_flags_kern.o $1 + [ $? -ne 0 ] && exit 1 +} + +function cleanup { + ip link del veth0b + ip netns delete at_ns0 + umount /tmp/cgroupv2 + rm -rf /tmp/cgroupv2 +} + +cleanup 2>/dev/null + +set -e +config_device +config_cgroup +set +e + +# +# Test 1 - fail ping6 +# +attach_bpf 0 +ping -c1 -w1 172.16.1.100 +if [ $? -ne 0 ]; then + echo "ping failed when it should succeed" + cleanup + exit 1 +fi + +ping6 -c1 -w1 2401:db00::1 +if [ $? -eq 0 ]; then + echo "ping6 succeeded when it should not" + cleanup + exit 1 +fi + +# +# Test 2 - fail ping +# +attach_bpf 1 +ping6 -c1 -w1 2401:db00::1 +if [ $? -ne 0 ]; then + echo "ping6 failed when it should succeed" + cleanup + exit 1 +fi + +ping -c1 -w1 172.16.1.100 +if [ $? -eq 0 ]; then + echo "ping succeeded when it should not" + cleanup + exit 1 +fi + +cleanup +echo +echo "*** PASS ***" -- cgit v1.1