]>
Commit | Line | Data |
---|---|---|
9b474ece SD |
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 | ||
d40fc181 JS |
35 | char bpf_log_buf[BPF_LOG_BUF_SIZE]; |
36 | ||
9b474ece SD |
37 | static int prog_load(int verdict) |
38 | { | |
39 | int ret; | |
40 | struct bpf_insn prog[] = { | |
41 | BPF_MOV64_IMM(BPF_REG_0, verdict), /* r0 = verdict */ | |
42 | BPF_EXIT_INSN(), | |
43 | }; | |
43371c83 | 44 | size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn); |
9b474ece | 45 | |
d40fc181 | 46 | ret = bpf_load_program(BPF_PROG_TYPE_CGROUP_SKB, |
43371c83 | 47 | prog, insns_cnt, "GPL", 0, |
d40fc181 | 48 | bpf_log_buf, BPF_LOG_BUF_SIZE); |
9b474ece SD |
49 | |
50 | if (ret < 0) { | |
51 | log_err("Loading program"); | |
52 | printf("Output from verifier:\n%s\n-------\n", bpf_log_buf); | |
53 | return 0; | |
54 | } | |
55 | return ret; | |
56 | } | |
57 | ||
58 | ||
59 | int main(int argc, char **argv) | |
60 | { | |
61 | int drop_prog, allow_prog, foo = 0, bar = 0, rc = 0; | |
62 | ||
63 | allow_prog = prog_load(1); | |
64 | if (!allow_prog) | |
65 | goto err; | |
66 | ||
67 | drop_prog = prog_load(0); | |
68 | if (!drop_prog) | |
69 | goto err; | |
70 | ||
71 | if (setup_cgroup_environment()) | |
72 | goto err; | |
73 | ||
74 | /* Create cgroup /foo, get fd, and join it */ | |
75 | foo = create_and_get_cgroup(FOO); | |
76 | if (!foo) | |
77 | goto err; | |
78 | ||
79 | if (join_cgroup(FOO)) | |
80 | goto err; | |
81 | ||
82 | if (bpf_prog_attach(drop_prog, foo, BPF_CGROUP_INET_EGRESS)) { | |
83 | log_err("Attaching prog to /foo"); | |
84 | goto err; | |
85 | } | |
86 | ||
87 | assert(system(PING_CMD) != 0); | |
88 | ||
89 | /* Create cgroup /foo/bar, get fd, and join it */ | |
90 | bar = create_and_get_cgroup(BAR); | |
91 | if (!bar) | |
92 | goto err; | |
93 | ||
94 | if (join_cgroup(BAR)) | |
95 | goto err; | |
96 | ||
97 | assert(system(PING_CMD) != 0); | |
98 | ||
99 | if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { | |
100 | log_err("Attaching prog to /foo/bar"); | |
101 | goto err; | |
102 | } | |
103 | ||
104 | assert(system(PING_CMD) == 0); | |
105 | ||
106 | ||
107 | if (bpf_prog_detach(bar, BPF_CGROUP_INET_EGRESS)) { | |
108 | log_err("Detaching program from /foo/bar"); | |
109 | goto err; | |
110 | } | |
111 | ||
112 | assert(system(PING_CMD) != 0); | |
113 | ||
114 | if (bpf_prog_attach(allow_prog, bar, BPF_CGROUP_INET_EGRESS)) { | |
115 | log_err("Attaching prog to /foo/bar"); | |
116 | goto err; | |
117 | } | |
118 | ||
119 | if (bpf_prog_detach(foo, BPF_CGROUP_INET_EGRESS)) { | |
120 | log_err("Detaching program from /foo"); | |
121 | goto err; | |
122 | } | |
123 | ||
124 | assert(system(PING_CMD) == 0); | |
125 | ||
126 | goto out; | |
127 | ||
128 | err: | |
129 | rc = 1; | |
130 | ||
131 | out: | |
132 | close(foo); | |
133 | close(bar); | |
134 | cleanup_cgroup_environment(); | |
135 | return rc; | |
136 | } |