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Commit | Line | Data |
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d8c5b17f DM |
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 | * | |
d8c5b17f DM |
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 <stddef.h> | |
24 | #include <string.h> | |
25 | #include <unistd.h> | |
26 | #include <assert.h> | |
27 | #include <errno.h> | |
28 | #include <fcntl.h> | |
29 | ||
30 | #include <linux/bpf.h> | |
31 | ||
32 | #include "libbpf.h" | |
33 | ||
34 | enum { | |
35 | MAP_KEY_PACKETS, | |
36 | MAP_KEY_BYTES, | |
37 | }; | |
38 | ||
39 | static int prog_load(int map_fd, int verdict) | |
40 | { | |
41 | struct bpf_insn prog[] = { | |
42 | BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), /* save r6 so it's not clobbered by BPF_CALL */ | |
43 | ||
44 | /* Count packets */ | |
45 | BPF_MOV64_IMM(BPF_REG_0, MAP_KEY_PACKETS), /* r0 = 0 */ | |
46 | BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */ | |
47 | BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), | |
48 | BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */ | |
49 | BPF_LD_MAP_FD(BPF_REG_1, map_fd), /* load map fd to r1 */ | |
50 | BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
51 | BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), | |
52 | BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */ | |
53 | BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */ | |
54 | ||
55 | /* Count bytes */ | |
56 | BPF_MOV64_IMM(BPF_REG_0, MAP_KEY_BYTES), /* r0 = 1 */ | |
57 | BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */ | |
58 | BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), | |
59 | BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */ | |
60 | BPF_LD_MAP_FD(BPF_REG_1, map_fd), | |
61 | BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), | |
62 | BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), | |
63 | BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6, offsetof(struct __sk_buff, len)), /* r1 = skb->len */ | |
64 | BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */ | |
65 | ||
66 | BPF_MOV64_IMM(BPF_REG_0, verdict), /* r0 = verdict */ | |
67 | BPF_EXIT_INSN(), | |
68 | }; | |
69 | ||
70 | return bpf_prog_load(BPF_PROG_TYPE_CGROUP_SKB, | |
71 | prog, sizeof(prog), "GPL", 0); | |
72 | } | |
73 | ||
74 | static int usage(const char *argv0) | |
75 | { | |
1379fd3c SD |
76 | printf("Usage: %s [-d] [-D] <cg-path> <egress|ingress>\n", argv0); |
77 | printf(" -d Drop Traffic\n"); | |
78 | printf(" -D Detach filter, and exit\n"); | |
d8c5b17f DM |
79 | return EXIT_FAILURE; |
80 | } | |
81 | ||
1379fd3c | 82 | static int attach_filter(int cg_fd, int type, int verdict) |
d8c5b17f | 83 | { |
1379fd3c | 84 | int prog_fd, map_fd, ret, key; |
d8c5b17f | 85 | long long pkt_cnt, byte_cnt; |
d8c5b17f DM |
86 | |
87 | map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, | |
88 | sizeof(key), sizeof(byte_cnt), | |
89 | 256, 0); | |
90 | if (map_fd < 0) { | |
91 | printf("Failed to create map: '%s'\n", strerror(errno)); | |
92 | return EXIT_FAILURE; | |
93 | } | |
94 | ||
95 | prog_fd = prog_load(map_fd, verdict); | |
96 | printf("Output from kernel verifier:\n%s\n-------\n", bpf_log_buf); | |
97 | ||
98 | if (prog_fd < 0) { | |
99 | printf("Failed to load prog: '%s'\n", strerror(errno)); | |
100 | return EXIT_FAILURE; | |
101 | } | |
102 | ||
d8c5b17f DM |
103 | ret = bpf_prog_attach(prog_fd, cg_fd, type); |
104 | if (ret < 0) { | |
105 | printf("Failed to attach prog to cgroup: '%s'\n", | |
106 | strerror(errno)); | |
107 | return EXIT_FAILURE; | |
108 | } | |
d8c5b17f DM |
109 | while (1) { |
110 | key = MAP_KEY_PACKETS; | |
111 | assert(bpf_lookup_elem(map_fd, &key, &pkt_cnt) == 0); | |
112 | ||
113 | key = MAP_KEY_BYTES; | |
114 | assert(bpf_lookup_elem(map_fd, &key, &byte_cnt) == 0); | |
115 | ||
116 | printf("cgroup received %lld packets, %lld bytes\n", | |
117 | pkt_cnt, byte_cnt); | |
118 | sleep(1); | |
119 | } | |
120 | ||
121 | return EXIT_SUCCESS; | |
122 | } | |
1379fd3c SD |
123 | |
124 | int main(int argc, char **argv) | |
125 | { | |
126 | int detach_only = 0, verdict = 1; | |
127 | enum bpf_attach_type type; | |
128 | int opt, cg_fd, ret; | |
129 | ||
130 | while ((opt = getopt(argc, argv, "Dd")) != -1) { | |
131 | switch (opt) { | |
132 | case 'd': | |
133 | verdict = 0; | |
134 | break; | |
135 | case 'D': | |
136 | detach_only = 1; | |
137 | break; | |
138 | default: | |
139 | return usage(argv[0]); | |
140 | } | |
141 | } | |
142 | ||
143 | if (argc - optind < 2) | |
144 | return usage(argv[0]); | |
145 | ||
146 | if (strcmp(argv[optind + 1], "ingress") == 0) | |
147 | type = BPF_CGROUP_INET_INGRESS; | |
148 | else if (strcmp(argv[optind + 1], "egress") == 0) | |
149 | type = BPF_CGROUP_INET_EGRESS; | |
150 | else | |
151 | return usage(argv[0]); | |
152 | ||
153 | cg_fd = open(argv[optind], O_DIRECTORY | O_RDONLY); | |
154 | if (cg_fd < 0) { | |
155 | printf("Failed to open cgroup path: '%s'\n", strerror(errno)); | |
156 | return EXIT_FAILURE; | |
157 | } | |
158 | ||
159 | if (detach_only) { | |
160 | ret = bpf_prog_detach(cg_fd, type); | |
161 | printf("bpf_prog_detach() returned '%s' (%d)\n", | |
162 | strerror(errno), errno); | |
163 | } else | |
164 | ret = attach_filter(cg_fd, type, verdict); | |
165 | ||
166 | return ret; | |
167 | } |