From patchwork Wed Aug 17 14:00:48 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Mack X-Patchwork-Id: 660130 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3sDrkQ6zvFz9t2T for ; Thu, 18 Aug 2016 00:11:26 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752859AbcHQOLY (ORCPT ); Wed, 17 Aug 2016 10:11:24 -0400 Received: from svenfoo.org ([82.94.215.22]:47319 "EHLO mail.zonque.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752767AbcHQOLS (ORCPT ); Wed, 17 Aug 2016 10:11:18 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.zonque.de (Postfix) with ESMTP id 21626B8220; Wed, 17 Aug 2016 16:01:00 +0200 (CEST) Received: from mail.zonque.de ([127.0.0.1]) by localhost (rambrand.bugwerft.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Ght1qm9Jbeih; Wed, 17 Aug 2016 16:00:59 +0200 (CEST) Received: from rabotti.localdomain (p5DDC7225.dip0.t-ipconnect.de [93.220.114.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.zonque.de (Postfix) with ESMTPSA id 8789AB8223; Wed, 17 Aug 2016 16:00:59 +0200 (CEST) From: Daniel Mack To: htejun@fb.com, daniel@iogearbox.net, ast@fb.com Cc: davem@davemloft.net, kafai@fb.com, fw@strlen.de, pablo@netfilter.org, harald@redhat.com, netdev@vger.kernel.org, Daniel Mack Subject: [RFC PATCH 5/5] samples: bpf: add userspace example for attaching eBPF programs to cgroups Date: Wed, 17 Aug 2016 16:00:48 +0200 Message-Id: <1471442448-1248-6-git-send-email-daniel@zonque.org> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1471442448-1248-1-git-send-email-daniel@zonque.org> References: <1471442448-1248-1-git-send-email-daniel@zonque.org> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Add a simple userpace program to demonstrate the new API to attach eBPF programs to cgroups. This is what it does: * Create arraymap in kernel with 4 byte keys and 8 byte values * Load 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. * Detach any eBPF program previously attached to the cgroup * Attach the new program to the cgroup using BPF_PROG_ATTACH * Every second, read map[0] and map[1] to see how many bytes and packets were seen on any socket of tasks in the given cgroup. libbpf gained two new wrappers for the new syscall commands. Signed-off-by: Daniel Mack --- samples/bpf/Makefile | 2 + samples/bpf/libbpf.c | 21 +++++++ samples/bpf/libbpf.h | 3 + samples/bpf/test_cgrp2_attach.c | 136 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 162 insertions(+) create mode 100644 samples/bpf/test_cgrp2_attach.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 90ebf7d..2f1820c 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 @@ -46,6 +47,7 @@ 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 9969e35..9ce707b 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 364582b..f973241 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 0000000..9ec18cc --- /dev/null +++ b/samples/bpf/test_cgrp2_attach.c @@ -0,0 +1,136 @@ +/* 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 +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#include + +#include "libbpf.h" + +enum { + MAP_KEY_PACKETS, + MAP_KEY_BYTES, +}; + +static int prog_load(int map_fd) +{ + struct bpf_insn prog[] = { + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), /* save r6 so it's not clobbered by BPF_CALL */ + + 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 */ + + + 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, 1), /* r0 = 1 */ + BPF_EXIT_INSN(), + }; + + return bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCKET_FILTER, + prog, sizeof(prog), "GPL", 0); +} + +int main(int argc, char **argv) +{ + int cg_fd, map_fd, prog_fd, key, ret; + long long pkt_cnt, byte_cnt; + + if (argc < 2) { + printf("Usage: %s \n", argv[0]); + 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; + } + + 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); + 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_ATTACH_TYPE_CGROUP_INGRESS); + printf("bpf_prog_detach() returned '%s' (%d)\n", + strerror(errno), errno); + + ret = bpf_prog_attach(prog_fd, cg_fd, BPF_ATTACH_TYPE_CGROUP_INGRESS); + 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; +}