1 /* This test is a demo of using get_socket_uid and get_socket_cookie
2 * helper function to do per socket based network traffic monitoring.
3 * It requires iptables version higher then 1.6.1. to load pinned eBPF
4 * program into the xt_bpf match.
5 *
6 * TEST:
7 * ./run_cookie_uid_helper_example.sh -option
8 * option:
9 * -t: do traffic monitoring test, the program will continuously
10 * print out network traffic happens after program started A sample
11 * output is shown below:
12 *
13 * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
14 * cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
15 * cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
16 * cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
17 * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
18 * cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
19 * cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
20 * cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
21 *
22 * -s: do getsockopt SO_COOKIE test, the program will set up a pair of
23 * UDP sockets and send packets between them. And read out the traffic data
24 * directly from the ebpf map based on the socket cookie.
25 *
26 * Clean up: if using shell script, the script file will delete the iptables
27 * rule and unmount the bpf program when exit. Else the iptables rule need
28 * to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
29 */
30
31 #define _GNU_SOURCE
32
33 #define offsetof(type, member) __builtin_offsetof(type, member)
34 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
35
36 #include <arpa/inet.h>
37 #include <errno.h>
38 #include <error.h>
39 #include <limits.h>
40 #include <linux/bpf.h>
41 #include <linux/if_ether.h>
42 #include <net/if.h>
43 #include <signal.h>
44 #include <stdbool.h>
45 #include <stdint.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <string.h>
49 #include <sys/socket.h>
50 #include <sys/stat.h>
51 #include <sys/types.h>
52 #include <unistd.h>
53 #include <bpf/bpf.h>
54 #include "bpf_insn.h"
55
56 #define PORT 8888
57
58 struct stats {
59 uint32_t uid;
60 uint64_t packets;
61 uint64_t bytes;
62 };
63
64 static int map_fd, prog_fd;
65
66 static bool test_finish;
67
maps_create(void)68 static void maps_create(void)
69 {
70 map_fd = bpf_map_create(BPF_MAP_TYPE_HASH, NULL, sizeof(uint32_t),
71 sizeof(struct stats), 100, NULL);
72 if (map_fd < 0)
73 error(1, errno, "map create failed!\n");
74 }
75
prog_load(void)76 static void prog_load(void)
77 {
78 static char log_buf[1 << 16];
79
80 struct bpf_insn prog[] = {
81 /*
82 * Save sk_buff for future usage. value stored in R6 to R10 will
83 * not be reset after a bpf helper function call.
84 */
85 BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
86 /*
87 * pc1: BPF_FUNC_get_socket_cookie takes one parameter,
88 * R1: sk_buff
89 */
90 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
91 BPF_FUNC_get_socket_cookie),
92 /* pc2-4: save &socketCookie to r7 for future usage*/
93 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
94 BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
95 BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
96 /*
97 * pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
98 * it takes two parameters (R1: map_fd, R2: &socket_cookie)
99 */
100 BPF_LD_MAP_FD(BPF_REG_1, map_fd),
101 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
102 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
103 BPF_FUNC_map_lookup_elem),
104 /*
105 * pc9. if r0 != 0x0, go to pc+14, since we have the cookie
106 * stored already
107 * Otherwise do pc10-22 to setup a new data entry.
108 */
109 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
110 BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
111 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
112 BPF_FUNC_get_socket_uid),
113 /*
114 * Place a struct stats in the R10 stack and sequentially
115 * place the member value into the memory. Packets value
116 * is set by directly place a IMM value 1 into the stack.
117 */
118 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
119 -32 + (__s16)offsetof(struct stats, uid)),
120 BPF_ST_MEM(BPF_DW, BPF_REG_10,
121 -32 + (__s16)offsetof(struct stats, packets), 1),
122 /*
123 * __sk_buff is a special struct used for eBPF program to
124 * directly access some sk_buff field.
125 */
126 BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
127 offsetof(struct __sk_buff, len)),
128 BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
129 -32 + (__s16)offsetof(struct stats, bytes)),
130 /*
131 * add new map entry using BPF_FUNC_map_update_elem, it takes
132 * 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
133 * R4: flags)
134 */
135 BPF_LD_MAP_FD(BPF_REG_1, map_fd),
136 BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
137 BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
138 BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
139 BPF_MOV64_IMM(BPF_REG_4, 0),
140 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
141 BPF_FUNC_map_update_elem),
142 BPF_JMP_IMM(BPF_JA, 0, 0, 5),
143 /*
144 * pc24-30 update the packet info to a exist data entry, it can
145 * be done by directly write to pointers instead of using
146 * BPF_FUNC_map_update_elem helper function
147 */
148 BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
149 BPF_MOV64_IMM(BPF_REG_1, 1),
150 BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_9, BPF_REG_1,
151 offsetof(struct stats, packets)),
152 BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
153 offsetof(struct __sk_buff, len)),
154 BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_9, BPF_REG_1,
155 offsetof(struct stats, bytes)),
156 BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
157 offsetof(struct __sk_buff, len)),
158 BPF_EXIT_INSN(),
159 };
160 LIBBPF_OPTS(bpf_prog_load_opts, opts,
161 .log_buf = log_buf,
162 .log_size = sizeof(log_buf),
163 );
164
165 prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
166 prog, ARRAY_SIZE(prog), &opts);
167 if (prog_fd < 0)
168 error(1, errno, "failed to load prog\n%s\n", log_buf);
169 }
170
prog_attach_iptables(char * file)171 static void prog_attach_iptables(char *file)
172 {
173 int ret;
174 char rules[256];
175
176 if (bpf_obj_pin(prog_fd, file))
177 error(1, errno, "bpf_obj_pin");
178 if (strlen(file) > 50) {
179 printf("file path too long: %s\n", file);
180 exit(1);
181 }
182 ret = snprintf(rules, sizeof(rules),
183 "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
184 file);
185 if (ret < 0 || ret >= sizeof(rules)) {
186 printf("error constructing iptables command\n");
187 exit(1);
188 }
189 ret = system(rules);
190 if (ret < 0) {
191 printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
192 exit(1);
193 }
194 }
195
print_table(void)196 static void print_table(void)
197 {
198 struct stats curEntry;
199 uint32_t curN = UINT32_MAX;
200 uint32_t nextN;
201 int res;
202
203 while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
204 curN = nextN;
205 res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
206 if (res < 0) {
207 error(1, errno, "fail to get entry value of Key: %u\n",
208 curN);
209 } else {
210 printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
211 " Bytes Count: %lu\n", curN, curEntry.uid,
212 curEntry.packets, curEntry.bytes);
213 }
214 }
215 }
216
udp_client(void)217 static void udp_client(void)
218 {
219 struct sockaddr_in si_other = {0};
220 struct sockaddr_in si_me = {0};
221 struct stats dataEntry;
222 int s_rcv, s_send, i, recv_len;
223 char message = 'a';
224 char buf;
225 uint64_t cookie;
226 int res;
227 socklen_t cookie_len = sizeof(cookie);
228 socklen_t slen = sizeof(si_other);
229
230 s_rcv = socket(PF_INET, SOCK_DGRAM, 0);
231 if (s_rcv < 0)
232 error(1, errno, "rcv socket creat failed!\n");
233 si_other.sin_family = AF_INET;
234 si_other.sin_port = htons(PORT);
235 if (inet_aton("127.0.0.1", &si_other.sin_addr) == 0)
236 error(1, errno, "inet_aton\n");
237 if (bind(s_rcv, (struct sockaddr *)&si_other, sizeof(si_other)) == -1)
238 error(1, errno, "bind\n");
239 s_send = socket(PF_INET, SOCK_DGRAM, 0);
240 if (s_send < 0)
241 error(1, errno, "send socket creat failed!\n");
242 res = getsockopt(s_send, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
243 if (res < 0)
244 printf("get cookie failed: %s\n", strerror(errno));
245 res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
246 if (res != -1)
247 error(1, errno, "socket stat found while flow not active\n");
248 for (i = 0; i < 10; i++) {
249 res = sendto(s_send, &message, sizeof(message), 0,
250 (struct sockaddr *)&si_other, slen);
251 if (res == -1)
252 error(1, errno, "send\n");
253 if (res != sizeof(message))
254 error(1, 0, "%uB != %luB\n", res, sizeof(message));
255 recv_len = recvfrom(s_rcv, &buf, sizeof(buf), 0,
256 (struct sockaddr *)&si_me, &slen);
257 if (recv_len < 0)
258 error(1, errno, "receive\n");
259 res = memcmp(&(si_other.sin_addr), &(si_me.sin_addr),
260 sizeof(si_me.sin_addr));
261 if (res != 0)
262 error(1, EFAULT, "sender addr error: %d\n", res);
263 printf("Message received: %c\n", buf);
264 res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
265 if (res < 0)
266 error(1, errno, "lookup sk stat failed, cookie: %lu\n",
267 cookie);
268 printf("cookie: %lu, uid: 0x%x, Packet Count: %lu,"
269 " Bytes Count: %lu\n\n", cookie, dataEntry.uid,
270 dataEntry.packets, dataEntry.bytes);
271 }
272 close(s_send);
273 close(s_rcv);
274 }
275
usage(void)276 static int usage(void)
277 {
278 printf("Usage: ./run_cookie_uid_helper_example.sh"
279 " bpfObjName -option\n"
280 " -t traffic monitor test\n"
281 " -s getsockopt cookie test\n");
282 return 1;
283 }
284
finish(int ret)285 static void finish(int ret)
286 {
287 test_finish = true;
288 }
289
main(int argc,char * argv[])290 int main(int argc, char *argv[])
291 {
292 int opt;
293 bool cfg_test_traffic = false;
294 bool cfg_test_cookie = false;
295
296 if (argc != 3)
297 return usage();
298 while ((opt = getopt(argc, argv, "ts")) != -1) {
299 switch (opt) {
300 case 't':
301 cfg_test_traffic = true;
302 break;
303 case 's':
304 cfg_test_cookie = true;
305 break;
306
307 default:
308 printf("unknown option %c\n", opt);
309 usage();
310 return -1;
311 }
312 }
313 maps_create();
314 prog_load();
315 prog_attach_iptables(argv[2]);
316 if (cfg_test_traffic) {
317 if (signal(SIGINT, finish) == SIG_ERR)
318 error(1, errno, "register SIGINT handler failed");
319 if (signal(SIGTERM, finish) == SIG_ERR)
320 error(1, errno, "register SIGTERM handler failed");
321 while (!test_finish) {
322 print_table();
323 printf("\n");
324 sleep(1);
325 }
326 } else if (cfg_test_cookie) {
327 udp_client();
328 }
329 close(prog_fd);
330 close(map_fd);
331 return 0;
332 }
333