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_create_map(BPF_MAP_TYPE_HASH, sizeof(uint32_t),
71 sizeof(struct stats), 100, 0);
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 prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
161 ARRAY_SIZE(prog), "GPL", 0,
162 log_buf, sizeof(log_buf));
163 if (prog_fd < 0)
164 error(1, errno, "failed to load prog\n%s\n", log_buf);
165 }
166
prog_attach_iptables(char * file)167 static void prog_attach_iptables(char *file)
168 {
169 int ret;
170 char rules[100];
171
172 if (bpf_obj_pin(prog_fd, file))
173 error(1, errno, "bpf_obj_pin");
174 if (strlen(file) > 50) {
175 printf("file path too long: %s\n", file);
176 exit(1);
177 }
178 sprintf(rules, "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
179 file);
180 ret = system(rules);
181 if (ret < 0) {
182 printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
183 exit(1);
184 }
185 }
186
print_table(void)187 static void print_table(void)
188 {
189 struct stats curEntry;
190 uint32_t curN = UINT32_MAX;
191 uint32_t nextN;
192 int res;
193
194 while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
195 curN = nextN;
196 res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
197 if (res < 0) {
198 error(1, errno, "fail to get entry value of Key: %u\n",
199 curN);
200 } else {
201 printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
202 " Bytes Count: %lu\n", curN, curEntry.uid,
203 curEntry.packets, curEntry.bytes);
204 }
205 }
206 }
207
udp_client(void)208 static void udp_client(void)
209 {
210 struct sockaddr_in si_other = {0};
211 struct sockaddr_in si_me = {0};
212 struct stats dataEntry;
213 int s_rcv, s_send, i, recv_len;
214 char message = 'a';
215 char buf;
216 uint64_t cookie;
217 int res;
218 socklen_t cookie_len = sizeof(cookie);
219 socklen_t slen = sizeof(si_other);
220
221 s_rcv = socket(PF_INET, SOCK_DGRAM, 0);
222 if (s_rcv < 0)
223 error(1, errno, "rcv socket creat failed!\n");
224 si_other.sin_family = AF_INET;
225 si_other.sin_port = htons(PORT);
226 if (inet_aton("127.0.0.1", &si_other.sin_addr) == 0)
227 error(1, errno, "inet_aton\n");
228 if (bind(s_rcv, (struct sockaddr *)&si_other, sizeof(si_other)) == -1)
229 error(1, errno, "bind\n");
230 s_send = socket(PF_INET, SOCK_DGRAM, 0);
231 if (s_send < 0)
232 error(1, errno, "send socket creat failed!\n");
233 res = getsockopt(s_send, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
234 if (res < 0)
235 printf("get cookie failed: %s\n", strerror(errno));
236 res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
237 if (res != -1)
238 error(1, errno, "socket stat found while flow not active\n");
239 for (i = 0; i < 10; i++) {
240 res = sendto(s_send, &message, sizeof(message), 0,
241 (struct sockaddr *)&si_other, slen);
242 if (res == -1)
243 error(1, errno, "send\n");
244 if (res != sizeof(message))
245 error(1, 0, "%uB != %luB\n", res, sizeof(message));
246 recv_len = recvfrom(s_rcv, &buf, sizeof(buf), 0,
247 (struct sockaddr *)&si_me, &slen);
248 if (recv_len < 0)
249 error(1, errno, "receive\n");
250 res = memcmp(&(si_other.sin_addr), &(si_me.sin_addr),
251 sizeof(si_me.sin_addr));
252 if (res != 0)
253 error(1, EFAULT, "sender addr error: %d\n", res);
254 printf("Message received: %c\n", buf);
255 res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
256 if (res < 0)
257 error(1, errno, "lookup sk stat failed, cookie: %lu\n",
258 cookie);
259 printf("cookie: %lu, uid: 0x%x, Packet Count: %lu,"
260 " Bytes Count: %lu\n\n", cookie, dataEntry.uid,
261 dataEntry.packets, dataEntry.bytes);
262 }
263 close(s_send);
264 close(s_rcv);
265 }
266
usage(void)267 static int usage(void)
268 {
269 printf("Usage: ./run_cookie_uid_helper_example.sh"
270 " bpfObjName -option\n"
271 " -t traffic monitor test\n"
272 " -s getsockopt cookie test\n");
273 return 1;
274 }
275
finish(int ret)276 static void finish(int ret)
277 {
278 test_finish = true;
279 }
280
main(int argc,char * argv[])281 int main(int argc, char *argv[])
282 {
283 int opt;
284 bool cfg_test_traffic = false;
285 bool cfg_test_cookie = false;
286
287 if (argc != 3)
288 return usage();
289 while ((opt = getopt(argc, argv, "ts")) != -1) {
290 switch (opt) {
291 case 't':
292 cfg_test_traffic = true;
293 break;
294 case 's':
295 cfg_test_cookie = true;
296 break;
297
298 default:
299 printf("unknown option %c\n", opt);
300 usage();
301 return -1;
302 }
303 }
304 maps_create();
305 prog_load();
306 prog_attach_iptables(argv[2]);
307 if (cfg_test_traffic) {
308 if (signal(SIGINT, finish) == SIG_ERR)
309 error(1, errno, "register SIGINT handler failed");
310 if (signal(SIGTERM, finish) == SIG_ERR)
311 error(1, errno, "register SIGTERM handler failed");
312 while (!test_finish) {
313 print_table();
314 printf("\n");
315 sleep(1);
316 }
317 } else if (cfg_test_cookie) {
318 udp_client();
319 }
320 close(prog_fd);
321 close(map_fd);
322 return 0;
323 }
324