| Sargun Dhillon | 9b474ec | 2016-12-02 02:42:32 -0800 | [diff] [blame^] | 1 | /* eBPF example program: |
| 2 | * |
| 3 | * - Creates arraymap in kernel with 4 bytes keys and 8 byte values |
| 4 | * |
| 5 | * - Loads eBPF program |
| 6 | * |
| 7 | * The eBPF program accesses the map passed in to store two pieces of |
| 8 | * information. The number of invocations of the program, which maps |
| 9 | * to the number of packets received, is stored to key 0. Key 1 is |
| 10 | * incremented on each iteration by the number of bytes stored in |
| 11 | * the skb. |
| 12 | * |
| 13 | * - Attaches the new program to a cgroup using BPF_PROG_ATTACH |
| 14 | * |
| 15 | * - Every second, reads map[0] and map[1] to see how many bytes and |
| 16 | * packets were seen on any socket of tasks in the given cgroup. |
| 17 | */ |
| 18 | |
| 19 | #define _GNU_SOURCE |
| 20 | |
| 21 | #include <stdio.h> |
| 22 | #include <stdlib.h> |
| 23 | #include <assert.h> |
| 24 | #include <unistd.h> |
| 25 | |
| 26 | #include <linux/bpf.h> |
| 27 | |
| 28 | #include "libbpf.h" |
| 29 | #include "cgroup_helpers.h" |
| 30 | |
| 31 | #define FOO "/foo" |
| 32 | #define BAR "/foo/bar/" |
| 33 | #define PING_CMD "ping -c1 -w1 127.0.0.1" |
| 34 | |
| 35 | static int prog_load(int verdict) |
| 36 | { |
| 37 | int ret; |
| 38 | struct bpf_insn prog[] = { |
| 39 | BPF_MOV64_IMM(BPF_REG_0, verdict), /* r0 = verdict */ |
| 40 | BPF_EXIT_INSN(), |
| 41 | }; |
| 42 | |
| 43 | ret = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SKB, |
| 44 | prog, sizeof(prog), "GPL", 0); |
| 45 | |
| 46 | if (ret < 0) { |
| 47 | log_err("Loading program"); |
| 48 | printf("Output from verifier:\n%s\n-------\n", bpf_log_buf); |
| 49 | return 0; |
| 50 | } |
| 51 | return ret; |
| 52 | } |
| 53 | |
| 54 | |
| 55 | int main(int argc, char **argv) |
| 56 | { |
| 57 | int drop_prog, allow_prog, foo = 0, bar = 0, rc = 0; |
| 58 | |
| 59 | allow_prog = prog_load(1); |
| 60 | if (!allow_prog) |
| 61 | goto err; |
| 62 | |
| 63 | drop_prog = prog_load(0); |
| 64 | if (!drop_prog) |
| 65 | goto err; |
| 66 | |
| 67 | if (setup_cgroup_environment()) |
| 68 | goto err; |
| 69 | |
| 70 | /* Create cgroup /foo, get fd, and join it */ |
| 71 | foo = create_and_get_cgroup(FOO); |
| 72 | if (!foo) |
| 73 | goto err; |
| 74 | |
| 75 | if (join_cgroup(FOO)) |
| 76 | goto err; |
| 77 | |
| 78 | if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS)) { |
| 79 | log_err("Attaching prog to /foo"); |
| 80 | goto err; |
| 81 | } |
| 82 | |
| 83 | assert(system(PING_CMD) != 0); |
| 84 | |
| 85 | /* Create cgroup /foo/bar, get fd, and join it */ |
| 86 | bar = create_and_get_cgroup(BAR); |
| 87 | if (!bar) |
| 88 | goto err; |
| 89 | |
| 90 | if (join_cgroup(BAR)) |
| 91 | goto err; |
| 92 | |
| 93 | assert(system(PING_CMD) != 0); |
| 94 | |
| 95 | if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { |
| 96 | log_err("Attaching prog to /foo/bar"); |
| 97 | goto err; |
| 98 | } |
| 99 | |
| 100 | assert(system(PING_CMD) == 0); |
| 101 | |
| 102 | |
| 103 | if (bpf_prog_detach(bar, BPF_CGROUP_INET_EGRESS)) { |
| 104 | log_err("Detaching program from /foo/bar"); |
| 105 | goto err; |
| 106 | } |
| 107 | |
| 108 | assert(system(PING_CMD) != 0); |
| 109 | |
| 110 | if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { |
| 111 | log_err("Attaching prog to /foo/bar"); |
| 112 | goto err; |
| 113 | } |
| 114 | |
| 115 | if (bpf_prog_detach(foo, BPF_CGROUP_INET_EGRESS)) { |
| 116 | log_err("Detaching program from /foo"); |
| 117 | goto err; |
| 118 | } |
| 119 | |
| 120 | assert(system(PING_CMD) == 0); |
| 121 | |
| 122 | goto out; |
| 123 | |
| 124 | err: |
| 125 | rc = 1; |
| 126 | |
| 127 | out: |
| 128 | close(foo); |
| 129 | close(bar); |
| 130 | cleanup_cgroup_environment(); |
| 131 | return rc; |
| 132 | } |